Coralline algal physiology is more adversely affected by elevated temperature than reduced pH.

PubMed

Vásquez-Elizondo, Román Manuel; Enríquez, Susana

2016-01-07

In this study we analyzed the physiological responses of coralline algae to ocean acidification (OA) and global warming, by exposing algal thalli of three species with contrasting photobiology and growth-form to reduced pH and elevated temperature. The analysis aimed to discern between direct and combined effects, while elucidating the role of light and photosynthesis inhibition in this response. We demonstrate the high sensitivity of coralline algae to photodamage under elevated temperature and its severe consequences on thallus photosynthesis and calcification rates. Moderate levels of light-stress, however, were maintained under reduced pH, resulting in no impact on algal photosynthesis, although moderate adverse effects on calcification rates were still observed. Accordingly, our results support the conclusion that global warming is a stronger threat to algal performance than OA, in particular in highly illuminated habitats such as coral reefs. We provide in this study a quantitative physiological model for the estimation of the impact of thermal-stress on coralline carbonate production, useful to foresee the impact of global warming on coralline contribution to reef carbon budgets, reef cementation, coral recruitment and the maintenance of reef biodiversity. This model, however, cannot yet account for the moderate physiological impact of low pH on coralline calcification.

Coralline algal physiology is more adversely affected by elevated temperature than reduced pH

NASA Astrophysics Data System (ADS)

Vásquez-Elizondo, Román Manuel; Enríquez, Susana

2016-01-01

In this study we analyzed the physiological responses of coralline algae to ocean acidification (OA) and global warming, by exposing algal thalli of three species with contrasting photobiology and growth-form to reduced pH and elevated temperature. The analysis aimed to discern between direct and combined effects, while elucidating the role of light and photosynthesis inhibition in this response. We demonstrate the high sensitivity of coralline algae to photodamage under elevated temperature and its severe consequences on thallus photosynthesis and calcification rates. Moderate levels of light-stress, however, were maintained under reduced pH, resulting in no impact on algal photosynthesis, although moderate adverse effects on calcification rates were still observed. Accordingly, our results support the conclusion that global warming is a stronger threat to algal performance than OA, in particular in highly illuminated habitats such as coral reefs. We provide in this study a quantitative physiological model for the estimation of the impact of thermal-stress on coralline carbonate production, useful to foresee the impact of global warming on coralline contribution to reef carbon budgets, reef cementation, coral recruitment and the maintenance of reef biodiversity. This model, however, cannot yet account for the moderate physiological impact of low pH on coralline calcification.

Stabilization of photosystem II reaction centers: influence of bile salt detergents and low pH.

PubMed

Gall, B; Scheer, H

1998-07-17

Rapid deterioration of samples is a major obstacle in research on the isolated reaction center of photosystem II. Its stability was tested systematically using a wide range of detergents, varying pH and temperature. Stability and activity did not depend on ionic properties of detergents or on critical micellar concentration. However, both were significantly increased by bile salt detergents in the dark as well as in the light. Low pH (5.5) and low temperature further improved stability. The results suggest that in particular the zwitterionic bile salt detergent, CHAPS, in pH 5.5 buffers is a very useful detergent and even superior to dodecylmaltoside for work with photosystem II reaction centers.

Effects of tetraethyl orthosilicate (TEOS) on the light and temperature stability of a pigment from Beta vulgaris and its potential food industry applications.

PubMed

Molina, Gustavo A; Hernández-Martínez, Angel Ramon; Cortez-Valadez, Manuel; García-Hernández, Fernando; Estevez, Miriam

2014-11-05

A novel, simple and inexpensive modification method using TEOS to increase the UV light, pH and temperature stability of a red-beet-pigment extracted from Beta vulgaris has been proposed. The effects on the molecular structure of betalains were studied by FTIR spectroscopy. The presence of betacyanin was verified by UV-Vis spectroscopy and its degradation in modified red-beet-pigment was evaluated and compared to the unmodified red-beet-pigment; performance improvements of 88.33%, 16.84% and 20.90% for UV light, pH and temperature stability were obtained, respectively,. Measurements of reducing sugars, phenol, and antioxidant contents were performed on unmodified and modified red-beet-pigment and losses of close to 21%, 54% and 36%, respectively, were found to be caused by the addition of TEOS. Polar diagrams of color by unmodified and modified red-beet-pigment in models of a beverage and of a yogurt were obtained and the color is preserved, although here is a small loss in the chromaticity parameter of the modified red-beet-pigment.

Influence of culture media and environmental factors on mycelial growth and sporulation of Lasiodiplodia theobromae (Pat.) Griffon and Maubl.

PubMed

Saha, A; Mandal, P; Dasgupta, S; Saha, D

2008-05-01

Lasiodiplodia theobromae, a common tea (Camellia sinensis) pathogen, usually does not sporulate or sporulates poorly in common media, which makes spore production difficult. In this study the effects of culture media, carbon source, nitrogen source, temperature, pH and light on mycelial growth and sporulation were evaluated. Among several carbon sources tested, glucose and sucrose were found superior for growth. Potassium nitrate supplemented media showed maximum growth amongst the tested inorganic nitrogen sources while peptone produced maximum growth among the tested organic nitrogen sources. Tea root extract supplemented potato dextrose agar medium was found to be the most suitable for mycelial growth and sporulation of L. theobromae. The fungus grow at temperatures ranging from 40 to 36 degrees C, with optimum growth at 28 degrees C and no growth was noted at 40 degrees C. There was no significant effect of different light period on growth of L. theobromae, but light enhanced sporulation. The fungus grow at pH 3.0-8.0 and optimum growth was observed at pH 6.0. Tea root extract supplemented potato dextrose agar medium with pH 6.0 was the most suitable for production of conidia of L. theobromae at 28 degrees C. Hence this media may be recommended for inoculum production for further studies.

Degradation of Kresoxim-Methyl in Water: Impact of Varying pH, Temperature, Light and Atmospheric CO2 Level.

PubMed

Khandelwal, Ashish; Gupta, Suman; Gajbhiye, Vijay T; Varghese, Eldho

2016-01-01

In the present investigation, persistence of kresoxim-methyl (a broad spectrum strobilurin fungicide) was studied in water. Results revealed that kresoxim-methyl readily form acid metabolite. Therefore, residues of kresoxim-methyl were quantified on the basis of parent molecule alone and sum total of kresoxim-methyl and its acid metabolite. In water, influence of various abiotic factors like pH, temperature, light and atmospheric carbon dioxide level on dissipation of kresoxim-methyl was studied. The half life value for kresoxim-methyl and total residue varied from 1 to 26.1 and 6.1 to 94.0 days under different conditions. Statistical analysis revealed the significant effect of abiotic factors on the dissipation of kresoxim-methyl from water.

Light Responsive Polymer Membranes: A Review

PubMed Central

Nicoletta, Fiore Pasquale; Cupelli, Daniela; Formoso, Patrizia; De Filpo, Giovanni; Colella, Valentina; Gugliuzza, Annarosa

2012-01-01

In recent years, stimuli responsive materials have gained significant attention in membrane separation processes due to their ability to change specific properties in response to small external stimuli, such as light, pH, temperature, ionic strength, pressure, magnetic field, antigen, chemical composition, and so on. In this review, we briefly report recent progresses in light-driven materials and membranes. Photo-switching mechanisms, valved-membrane fabrication and light-driven properties are examined. Advances and perspectives of light responsive polymer membranes in biotechnology, chemistry and biology areas are discussed. PMID:24957966

Influence of pH and light on the stability of some antioxidants.

PubMed

Racine, P

1981-06-01

Summary Many organic molecules can be oxidized in the presence of oxygen. Light and traces of heavy metal ions catalyse the process of oxidation. The addition of a very small quantity of antioxidant to alcoholic perfumes and cosmetic bases is often made to retard auto-oxidations. Among the parameters which could influence the efficiency of an antioxidant, its intrinsic stability should be considered in the medium to be protected. This stability might conceivably be influenced by the pH, the presence of light, heavy metal ions and microorganisms. In this study we have concentrated on the role played by the first two factors. To eliminate a possible interference by the last two, analytical grades reagents together with chelators and high proof (80% v/v) hydroalcoholic solutions have been used. The antioxidants tested were: BHT, BHA, ethyl gallate, 2, carboxy-6, hydroxy, 2, 5, 7, 8, tetramethyl chroman (Trolox C(R)) and D-L-alpha-tocopherol. Solutions of 0.5 mmol/kg of each antioxidant were prepared in 80% v/v hydroalcoholic solutions and the pH adjusted with citric acid and potassium hydroxyde or hydrochloric acid. The pH extended from 2.5 to 10 and thus largely covers the pH range of cosmetic products. Of each solution, 100ml were kept in hermetically closed 125ml white glass bottles stored at room temperature (22 +/- 2 degrees C) and kept in the dark or exposed to the diffuse daylight of the laboratory. The antioxidants concentrations were determined by linear sweep voltametry on gold or glassy carbon electrodes. Significant differences in behaviour were observed. BHA and BHT are stable regardless of light and pH except at high pH (

Optical pendulum effect in one-dimensional diffraction-thick porous silicon based photonic crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novikov, V. B., E-mail: vb.novikov@physics.msu.ru; Svyakhovskiy, S. E.; Maydykovskiy, A. I.

We present the realization of the multiperiodic optical pendulum effect in 1D porous silicon photonic crystals (PhCs) under dynamical Bragg diffraction in the Laue scheme. The diffraction-thick PhC contained 360 spatial periods with a large variation of the refractive index of adjacent layers of 0.4. The experiments reveal switching of the light leaving the PhC between the two spatial directions, which correspond to Laue diffraction maxima, as the fundamental wavelength or polarization of the incident light is varied. A similar effect can be achieved when the temperature of the sample or the intensity of the additional laser beam illuminating themore » crystal are changed. We show that in our PhC structures, the spectral period of the pendulum effect is down to 5 nm, while the thermal period is about 10 °C.« less

Erratum to ;Coastal water column ammonium and nitrite oxidation are decoupled in summer;

NASA Astrophysics Data System (ADS)

Heiss, Elise M.; Fulweiler, Robinson W.

2017-07-01

Water column nitrification is a key process in the nitrogen cycle as it links reduced and oxidized forms of nitrogen and also provides the substrate (nitrate) needed for reactive nitrogen removal by denitrification. We measured potential water column ammonium and nitrite oxidation rates at four sites along an estuary to continental shelf gradient over two summers. In most cases, nitrite oxidation rates outpaced ammonium oxidation rates. Overall, ammonium and nitrite oxidation rates were higher outside of the estuary, and this trend was primarily driven by higher oxidation rates in deeper waters. Additionally, both ammonium and nitrite oxidation rates were impacted by different in situ variables. Ammonium oxidation rates throughout the water column as a whole were most positively correlated to depth and salinity and negatively correlated to dissolved oxygen, light, and temperature. In contrast, nitrite oxidation rates throughout the water column were negatively correlated with temperature, light and pH. Multivariate regression analysis revealed that surface (<20 m) ammonium oxidation rates were most strongly predicted by substrate (NH4+), salinity, and light, while deep (>20 m) rates were regulated by temperature, light, and [H+] (i.e. pH). In addition, surface (<20 m) nitrite oxidation rates were best explained by [H+] alone, while [H+], temperature, and dissolved oxygen all played a role in predicting deep (>20 m) nitrite oxidation rates. These results support the growing body of evidence that ammonium oxidation and nitrite oxidation are not always coupled, should be measured separately, and are influenced by different environmental conditions.

Environmental Measurement in Schools: Electronics in Field Studies.

ERIC Educational Resources Information Center

Crellin, J. R.

1978-01-01

The use of environmental meters designed to measure conductivity, light level, oxygen, pH, sound, and temperature are discussed. Criteria for choosing suitable equipment are suggested and, where possible, cheaper alternatives are mentioned. (Author/BB)

pH and temperature dual-sensitive liposome gel based on novel cleavable mPEG-Hz-CHEMS polymeric vaginal delivery system

PubMed Central

Chen, Daquan; Sun, Kaoxiang; Mu, Hongjie; Tang, Mingtan; Liang, Rongcai; Wang, Aiping; Zhou, Shasha; Sun, Haijun; Zhao, Feng; Yao, Jianwen; Liu, Wanhui

2012-01-01

Background In this study, a pH and temperature dual-sensitive liposome gel based on a novel cleavable hydrazone-based pH-sensitive methoxy polyethylene glycol 2000-hydrazone-cholesteryl hemisuccinate (mPEG-Hz-CHEMS) polymer was used for vaginal administration. Methods The pH-sensitive, cleavable mPEG-Hz-CHEMS was designed as a modified pH-sensitive liposome that would selectively degrade under locally acidic vaginal conditions. The novel pH-sensitive liposome was engineered to form a thermogel at body temperature and to degrade in an acidic environment. Results A dual-sensitive liposome gel with a high encapsulation efficiency of arctigenin was formed and improved the solubility of arctigenin characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. The dual-sensitive liposome gel with a sol-gel transition at body temperature was degraded in a pH-dependent manner, and was stable for a long period of time at neutral and basic pH, but cleavable under acidic conditions (pH 5.0). Arctigenin encapsulated in a dual-sensitive liposome gel was more stable and less toxic than arctigenin loaded into pH-sensitive liposomes. In vitro drug release results indicated that dual-sensitive liposome gels showed constant release of arctigenin over 3 days, but showed sustained release of arctigenin in buffers at pH 7.4 and pH 9.0. Conclusion This research has shed some light on a pH and temperature dual-sensitive liposome gel using a cleavable mPEG-Hz-CHEMS polymer for vaginal delivery. PMID:22679372

A study of hydrogen peroxide chemistry and photochemistry in tea stain solution with relevance to clinical tooth whitening.

PubMed

Young, Nigel; Fairley, Peter; Mohan, Veena; Jumeaux, Coline

2012-12-01

Tooth whitening using hydrogen peroxide is a complex process, and there is still some controversy about the roles of pH, temperature, chemical activators, and the use of light irradiation. In this work the basic interactions between whitening agents and stain molecules are studied in simple solutions, thus avoiding the physics of diffusion and light penetration in the tooth to give clarity on the basic chemistry which is occurring. The absorbance of tea stain solution at 450 nm was measured over a period of 40 min, with various compositions of whitening agent added (including hydrogen peroxide, ferrous gluconate and potassium hydroxide) and at the same time the samples were subjected to blue light (465 nm) or infra-red light (850 nm) irradiation, or alternatively they were heated to 37°C. It is shown that the reaction rates between chromogens in the tea solution and hydrogen peroxide can be accelerated significantly using ferrous gluconate activator and blue light irradiation. Infra red irradiation does not increase the reaction rate through photochemistry, it serves only to increase the temperature. Raising the temperature leads to inefficiency through the acceleration of exothermic decomposition reactions which produce only water and oxygen. By carrying out work in simple solution it was possible to show that ferrous activators and blue light irradiation significantly enhance the whitening process, whereas infra red irradiation has no significant effect over heating. The importance of controlling the pH within the tooth structure during whitening is also demonstrated. Copyright © 2012 Elsevier Ltd. All rights reserved.

Organic cation rhodamines for screening organic cation transporters in early stages of drug development.

PubMed

Ugwu, Malachy C; Oli, Angus; Esimone, Charles O; Agu, Remigius U

The aim of this study was to investigate the suitability of rhodamine-123, rhodamine-6G and rhodamine B as non-radioactive probes for characterizing organic cation transporters in respiratory cells. Fluorescent characteristics of the compounds were validated under standard in vitro drug transport conditions (buffers, pH, and light). Uptake/transport kinetics and intracellular accumulation of the compounds were investigated. Uptake/transport mechanisms were investigated by comparing the effect of pH, temperature, concentration, polarity, OCTs/OCTNs inhibitors/substrates, and metabolic inhibitors on the cationic dyes uptake in Calu-3 cells. Fluorescence stability and intensity of the compounds were altered by buffer composition, light, and pH. Uptake of the dyes was concentration-, temperature- and pH-dependent. OCTs/OCTNs inhibitors significantly reduced intracellular accumulation of the compounds. Whereas rhodamine-B uptake was sodium-dependent, pH had no effect on rhodamine-123 and rhodamine-6G uptake. Transport of the dyes across the cells was polarized: (AP→BL>BL→AP transport) and saturable: {V max =14.08±2.074, K m =1821±380.4 (rhodamine-B); V max =6.555±0.4106, K m =1353±130.4 (rhodamine-123) and V max =0.3056±0.01402, K m =702.9±60.97 (rhodamine-6G)}. The dyes were co-localized with MitoTracker®, the mitochondrial marker. Cationic rhodamines, especially rhodamine-B and rhodamine- 6G can be used as organic cation transporter substrates in respiratory cells. During such studies, buffer selection, pH and light exposure should be taken into consideration. Copyright © 2016 Elsevier Inc. All rights reserved.

Structural, morphological and steady state photoluminescence spectroscopy studies of red Eu(3+)-doped Y2O3 nanophosphors prepared by the sol-gel method.

PubMed

Lamiri, Lyes; Guerbous, Lakhdar; Samah, Madani; Boukerika, Allaoua; Ouhenia, Salim

2015-12-01

Europium trivalent (Eu(3+))-doped Y2O3 nanopowders of different concentrations (0.5, 2.5, 5 or 7 at.%) were synthesized by the sol-gel method, at different pH values (pH 2, 5 or 8) and annealing temperatures (600 °C, 800 °C or 1000 °C). The nanopowders samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and steady state photoluminescence spectroscopy. The effect of pH of solution and annealing temperatures on structural, morphological and photoluminescence properties of Eu(3+)-doped Y2O3 were studied and are discussed. It was found that the average crystallite size of the nanopowders increased with increasing pH and annealing temperature values. The Y2O3:Eu(3+) material presented different morphology and its evolution depended on the pH value and the annealing temperature. Activation energies at different pH values were determined and are discussed. Under ultraviolet (UV) light excitation, Y2O3:Eu(3+) showed narrow emission peaks corresponding to the (5)D0- (7) FJ (J = 0, 1, 2 and 3) transitions of the Eu(3+) ion, with the most intense red emission at 611 assigned to forced electric dipole (5)D0 → (7)F2. The emission intensity became more intense with increasing annealing temperature and pH values, related to the improvement of crystalline quality. For the 1000 °C annealing temperature, the emission intensity presented a maximum at pH 5 related to the uniform cubic-shaped particles. It was found that for lower annealing temperatures (small crystallite size) the CTB (charge transfer band) position presented a red shift. Copyright © 2015 John Wiley & Sons, Ltd.

Metabolic Microenvironmental Control by Photosynthetic Biofilms under Changing Macroenvironmental Temperature and pH Conditions▿ †

PubMed Central

Bissett, Andrew; Reimer, Andreas; de Beer, Dirk; Shiraishi, Fumito; Arp, Gernot

2008-01-01

Ex situ microelectrode experiments, using cyanobacterial biofilms from karst water creeks, were conducted under various pH, temperature, and constant-alkalinity conditions to investigate the effects of changing environmental parameters on cyanobacterial photosynthesis-induced calcification. Microenvironmental chemical conditions around calcifying sites were controlled by metabolic activity over a wide range of photosynthesis and respiration rates, with little influence from overlying water conditions. Regardless of overlying water pH levels (from 7.8 to 8.9), pH at the biofilm surface was approximately 9.4 in the light and 7.8 in the dark. The same trend was observed at various temperatures (4°C and 17°C). Biological processes control the calcium carbonate saturation state (Ω) in these and similar systems and are able to maintain Ω at approximately constant levels over relatively wide environmental fluctuations. Temperature did, however, have an effect on calcification rate. Calcium flux in this system is limited by its diffusion coefficient, resulting in a higher calcium flux (calcification and dissolution) at higher temperatures, despite the constant, biologically mediated pH. The ability of biological systems to mitigate the effects of environmental perturbation is an important factor that must be considered when attempting to predict the effects of increased atmospheric partial CO2 pressure on processes such as calcification and in interpreting microfossils in the fossil record. PMID:18689512

Effect of culture condition on the growth, biochemical composition and EPA production of alkaliphilic Nitzschia plea isolated in the Southeast of China.

PubMed

Zhang, Dongmei; Wen, Shumei; Wu, Xia; Cong, Wei

2018-06-01

To overcome the contamination in open pond, microalgal strain selection should focus on species with tolerability to extreme environments. In this study, a native alkaliphilic algae, diatom Nitzschia plea was obtained in Southeast of China, which could tolerate high concentration of NaHCO 3 (0.15 mol/L) and high pH (> 10). The effects of initial pH, light intensity and temperature on cell growth, biochemical composition and fatty acid profile of N. plea were investigated. Results indicated its specific growth rate could reach 1.2 day -1 , lipid content was in the range 14.6-30.2% of dry weight, eicosapntemacnioc acid (EPA, C20:5) accounted for around 15% of total fatty acids. Alkalic condition benefited for both cell growth and EPA synthesis. Appropriately increasing light intensity and temperature could improve cell growth rate and lipid synthesis, although the proportion of EPA in total fatty acids decreased slightly. The optimal culture condition (pH 9.00, temperature 35.0 °C, light intensity 158.6 µmol/m 2 s) was suggested for maximum yield of EPA based on the response surface model. The overall biomass productivity and EPA productivity were 0.301 g/L/day and 7.43 mg/L/day, respectively. In conclusion, alkalic environment was helpful for the steady operation of open pond cultivation of N. plea with the characteristics of fast growth rate and high EPA content, which exhibited its commercial value.

High resolution microscopy reveals significant impacts of ocean acidification and warming on larval shell development in Laternula elliptica.

PubMed

Bylenga, Christine H; Cummings, Vonda J; Ryan, Ken G

2017-01-01

Environmental stressors impact marine larval growth rates, quality and sizes. Larvae of the Antarctic bivalve, Laternula elliptica, were raised to the D-larvae stage under temperature and pH conditions representing ambient and end of century projections (-1.6°C to +0.4°C and pH 7.98 to 7.65). Previous observations using light microscopy suggested pH had no influence on larval abnormalities in this species. Detailed analysis of the shell using SEM showed that reduced pH is in fact a major stressor during development for this species, producing D-larvae with abnormal shapes, deformed shell edges and irregular hinges, cracked shell surfaces and even uncalcified larvae. Additionally, reduced pH increased pitting and cracking on shell surfaces. Thus, apparently normal larvae may be compromised at the ultrastructural level and these larvae would be in poor condition at settlement, reducing juvenile recruitment and overall survival. Elevated temperatures increased prodissoconch II sizes. However, the overall impacts on larval shell quality and integrity with concurrent ocean acidification would likely overshadow any beneficial results from warmer temperatures, limiting populations of this prevalent Antarctic species.

Biophysical characterization and conformational stability of Ebola and Marburg virus-like particles.

PubMed

Hu, Lei; Trefethen, Jared M; Zeng, Yuhong; Yee, Luisa; Ohtake, Satoshi; Lechuga-Ballesteros, David; Warfield, Kelly L; Aman, M Javad; Shulenin, Sergey; Unfer, Robert; Enterlein, Sven G; Truong-Le, Vu; Volkin, David B; Joshi, Sangeeta B; Middaugh, C Russell

2011-12-01

The filoviruses, Ebola virus and Marburg virus, cause severe hemorrhagic fever with up to 90% human mortality. Virus-like particles of EBOV (eVLPs) and MARV (mVLPs) are attractive vaccine candidates. For the development of stable vaccines, the conformational stability of these two enveloped VLPs produced in insect cells was characterized by various spectroscopic techniques over a wide pH and temperature range. Temperature-induced aggregation of the VLPs at various pH values was monitored by light scattering. Temperature/pH empirical phase diagrams (EPDs) of the two VLPs were constructed to summarize the large volume of data generated. The EPDs show that both VLPs lose their conformational integrity above about 50°C-60°C, depending on solution pH. The VLPs were maximally thermal stable in solution at pH 7-8, with a significant reduction in stability at pH 5 and 6. They were much less stable in solution at pH 3-4 due to increased susceptibility of the VLPs to aggregation. The characterization data and conformational stability profiles from these studies provide a basis for selection of optimized solution conditions for further vaccine formulation and long-term stability studies of eVLPs and mVLPs. Copyright © 2011 Wiley-Liss, Inc.

Hydroponic system design with real time OS based on ARM Cortex-M microcontroller

NASA Astrophysics Data System (ADS)

Atmadja, Wiedjaja; Liawatimena, Suryadiputra; Lukas, Jonathan; Nata, Eka Putra Leo; Alexander, Ivan

2017-12-01

Hydroponic is the process of growing plants without soil, plant root flooded or moist with nutrient-rich solutions in inert material. Hydroponics has become a reality for greenhouse growers in virtually all climates. Large hydroponic installations exist throughout the world for growing flowers, vegetables and some short period fruit like tomato and cucumber. In soilless culture, we must maintain stable pH and conductivity level of nutrient solution to make plant grow well, large variation of pH of certain time will poisoned plant. This paper describes development complete automation hydroponic system, from maintaining stable nutrient composition (conductivity and pH), grow light, and monitor plant environment such as CO2, temperature and humidity. The heart of our automation is ARM Cortex-M4 from ST Microelectronic running ARM mbed OS, the official Real Time Operating System (RTOS) for ARM Cortex-M microcontroller. Using RTOS gives us flexibility to have multithreaded process. Results show that system capable to control desired concentration level with variation of less than 3%, pH sensor show good accuracy 5.83% from pH value 3.23-10. Growing light intensity measurement show result 105 μmol/m2/s therefore we need turn on the light at least 17 hours/day to fulfil plant light requirement. RTOS give good performance with latency and jitter less than 15 us, system overall show good performance and accuracy for automating hydroponic plant in vegetative phase of growth.

Molecularly designed water soluble, intelligent, nanosize polymeric carriers.

PubMed

Pişkin, Erhan

2004-06-11

Intelligent polymers, also referred as "stimuli-responsive polymers" undergo strong property changes (in shape, surface characteristics, solubility, etc.) when only small changes in their environment (changes in temperature, pH, ionic strength light, electrical and magnetic field, etc.). They have been used in several novel applications, drug delivery systems, tissue engineering scaffolds, bioseparation, biomimetic actuators, etc. The most popular member of these type of polymers is poly(N-isopropylacrylamide) (poly(NIPA)) which exhibits temperature-sensitive character, in which the polymer chains change from water-soluble coils to water-insoluble globules in aqueous solution as temperature increases above the lower critical solution temperature (LCST) of the polymer. Copolymerization of NIPA with acrylic acid (AAc) allows the synthesis of both pH and temperature-responsive copolymers. This paper summarizes some of our related studies in which NIPA and its copolymers were synthesized and used as intelligent carriers in diverse applications.

Stability studies on florfenicol using developed derivative spectrophotometric methods.

PubMed

Elimam, M M; Shantier, S W; Gadkariem, E A; Mohamed, M A; Osman, Z

2017-01-01

This study aims to investigate the stability of florfenicol using previously developed derivative spectrophotometric methods (D 1 and D 2 ). The studied stability-indicating pararmeters included alkali (NaOH, 1M), acid (HCl, 1M), pH changes (buffer pH 2.2-11), temperature (80°C and 100°C at pH 10) and light. A constructed pH profile for the drug degradation rate revealed a significant effect of pH on the drug stability between pH ranges 8 and 11. The obtained profile indicated first order dependence of K obs on [OH - ]. Arrhenius plot at pH 10 was found linear at temperatures 80°C and 100°C with estimated activation energy of 19.35kcal/mol. The calculated rate constant (K obs ), t ½ and t 90 at 25°C were found to be 1.8×10 -3 h, 385h and 58.3h, respectively. The photostability of florfenicol was also studied by exposing the drug solution to direct sunlight during mid-day time. The obtained results reflected the instability of florfenicol under the study conditions. Copyright © 2016 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.

Casein maps: Effect of ethanol, pH, temperature, and CaCl2 on the particle size of reconstituted casein micelles

PubMed Central

Ye, Ran; Harte, Federico

2015-01-01

Although conditions favoring casein micelle aggregation are well known, factors promoting the dissociation of the casein micelle are not fully understood. It was our objective to investigate the ethanol-induced dissociation of micellar casein as affected by temperature and a wide range of pH, along with the concentrations of calcium and casein. Two different concentrations of casein micelles were dispersed in imidazole buffer with 0 to 80% ethanol (vol/vol) and 2 and 10 mM calcium. Apparent micelle size was determined by dynamic light scattering at 5, 30, and 60°C. In the absence of ethanol, casein precipitation occurred at pH 4.6 in imidazole buffer. Ten to forty percent ethanol promoted casein aggregation (>1,000 nm) and higher temperature (30 and 60°C) enhanced this effect. Higher ethanol concentrations at 50 to 80% induced the dissociation (<40 nm) of the casein micelle upon acidification (pH <5) and alkalization (pH >8) in imidazole buffer. In addition, higher concentrations of casein (0.25 mg/mL) and calcium (20 mM) caused the formation of larger aggregates (>1,000 nm) in the presence of ethanol when comparing with the initial lower concentrations of casein (0.1 mg/mL) and calcium (2 mM). Casein micelle dissociation can be achieved near the isoelectric pH by modifying the solvent composition and temperature. PMID:23200467

Casein maps: effect of ethanol, pH, temperature, and CaCl2 on the particle size of reconstituted casein micelles.

PubMed

Ye, Ran; Harte, Federico

2013-02-01

Although conditions favoring casein micelle aggregation are well known, factors promoting the dissociation of the casein micelle are not fully understood. It was our objective to investigate the ethanol-induced dissociation of micellar casein as affected by temperature and a wide range of pH, along with the concentrations of calcium and casein. Two different concentrations of casein micelles were dispersed in imidazole buffer with 0 to 80% ethanol (vol/vol) and 2 and 10mM calcium. Apparent micelle size was determined by dynamic light scattering at 5, 30, and 60°C. In the absence of ethanol, casein precipitation occurred at pH 4.6 in imidazole buffer. Ten to forty percent ethanol promoted casein aggregation (>1,000 nm) and higher temperature (30 and 60°C) enhanced this effect. Higher ethanol concentrations at 50 to 80% induced the dissociation (<40 nm) of the casein micelle upon acidification (pH <5) and alkalization (pH>8) in imidazole buffer. In addition, higher concentrations of casein (0.25mg/mL) and calcium (20mM) caused the formation of larger aggregates (>1,000 nm) in the presence of ethanol when comparing with the initial lower concentrations of casein (0.1mg/mL) and calcium (2mM). Casein micelle dissociation can be achieved near the isoelectric pH by modifying the solvent composition and temperature. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Casein micelle dissociation in skim milk during high-pressure treatment: effects of pressure, pH, and temperature.

PubMed

Orlien, V; Boserup, L; Olsen, K

2010-01-01

The effect of pH (from 5.5 to 7.5) and temperature (from 5 to 40 degrees C) on the turbidity of reconstituted skim milk powder was investigated at ambient pressure and in situ under pressure (up to 500MPa) by measurement of light scattering. High-pressure treatment reduced the turbidity of milk for all combinations of pH and temperature due to micelle dissociation. The turbidity profiles had a characteristic sigmoidal shape in which almost no effect on turbidity was observed at low pressures (100MPa), followed by a stronger pressure dependency over a pressure range of 150MPa during which turbidity decreased extremely. From the turbidity profiles, the threshold pressure for disruption of micelle integrity was determined and ranged from 150MPa at low pH to 350-400MPa at high pH. The threshold pressure diagram clearly showed a relationship between the barostability of casein micelles and pH, whereas almost no effect of temperature was shown. This remarkable pH effect was a consequence of pressure-induced changes in the electrostatic interactions between colloidal calcium phosphate and the caseins responsible for maintaining micellar structure and was explained by a shift in the calcium phosphate balance in the micelle-serum system. Accordingly, a mechanism for high pressure-induced disruption of micelle integrity is suggested in which the state of calcium plays a crucial role in the micelle dissociation process. Copyright 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Kinetic study of acetaminophen degradation by visible light photocatalysis.

PubMed

Gotostos, Mary Jane N; Su, Chia-Chi; De Luna, Mark Daniel G; Lu, Ming-Chun

2014-01-01

In this work, a novel photocatalyst K3[Fe(CN)6]/TiO2 synthesized via a simple sol-gel method was utilized to degrade acetaminophen (ACT) under visible light with the use of blue and green LED lights. Parameters (medium pH, initial concentration of reactant, catalyst concentration, temperature, and number of blue LED lights) affecting photocatalytic degradation of ACT were also investigated. The experimental result showed that compared to commercially available Degussa P-25 (DP-25) photocatalyst, K3[Fe(CN)6]/TiO2 gave higher degradation efficiency and rate constant (kapp) of ACT. The degradation efficiency or kapp decreased with increasing initial ACT concentration and temperature, but increased with increased number of blue LED lamps. Additionally, kapp increased as initial pH was increased from 5.6 to 6.9, but decreased at a high alkaline condition (pH 8.3). Furthermore, the degradation efficiency and kapp of ACT increased as K3[Fe(CN)6]/TiO2 loading was increased to 1 g L(-1) but decreased and eventually leveled off at photocatalyst loading above this value. Photocatalytic degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system follows a pseudo-first-order kinetics. The Langmuir-Hinshelwood equation was also satisfactorily used to model the degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system indicated by a satisfactory linear correlation between 1/kapp and Co, with kini = 6.54 × 10(-4) mM/min and KACT = 17.27 mM(-1).

Light Scattering Characterization of Elastin-Like Polypeptide Trimer Micelles

NASA Astrophysics Data System (ADS)

Tsuper, Ilona; Terrano, Daniel; Maraschky, Adam; Holland, Nolan; Streletzky, Kiril

The elastin-like polypeptides (ELP) nanoparticles are composed of three-armed star polypeptides connected by a negatively charged foldon. Each of the three arms extending from the foldon domain includes 20 repeats of the (GVGVP) amino acid sequence. The ELP polymer chains are soluble at room temperature and become insoluble at the transition temperature (close to 50 ° C), forming micelles. The size and shape of the micelle are dependent on the temperature and the pH of the solution, and on the concentration of the phosphate buffered saline (PBS). The depolarized dynamic light scattering (DDLS) was employed to study the structure and dynamics of micelles at 62 ° C. The solution was maintained at an approximate pH level of 7.3 - 7.5, while varying PBS concentration. At low salt concentrations (<15 mM), the micelle radius was about 10nm but not very reproducible on account of unstable pH levels arising from low buffer concentrations. At intermediate salt concentrations (15 - 60 mM), the system formed spherically-shaped micelles, exhibiting a steady growth in the hydrodynamic radius (Rh) from 10 to 21 nm, with increasing PBS concentration. Interestingly, higher salt concentrations (>60 mM) displayed an apparent elongation of the micelles evident by a significant VH signal, along with a surge in the apparent Rh. A model of micelle growth (and potential elongation) with increase in salt concentration is considered.

Phacidiopycnis washingtonensis--a new species associated with pome fruits from Washington State.

PubMed

Xiao, C L; Rogers, J D; Kim, Y K; Liu, Q

2005-01-01

A new species of Phacidiopycnis associated with pome fruits is described. The fungus causes fruit rot on apples during storage and is associated with a twig dieback and canker disease of crabapple trees and dead twigs of pear trees. To characterize the biology of the fungus and compare it with Ph. piri, the type species of the genus, effects of nine media and light on mycelial growth and pycnidial production, mycelial growth in response to temperature and mode of conidial germination in response to nutrient were determined. Apple-juice agar, pear-juice agar, prune-juice agar, potato-dextrose agar (PDA) and malt-extract agar, Czapek-Dox agar and oatmeal agar (OMA) favored mycelial growth. Cornmeal agar (CMA) did not favor mycelial growth. Light effect on pycnidial formation was medium dependent. Abundant pycnidia with mature conidia formed in 14 d old PDA and OMA cultures at 20 C, regardless of light, whereas none or very few pycnidia formed on other media in the dark. Fluorescent light stimulated formation of pycnidia except on CMA. The fungus grew at -3-25 C, with optimum growth at 15-20 C. Conidia germinated either by forming germ tubes or less often by budding. Budding of conidia occurred in 1 and 10% pear-juice solutions but not in 100% pear-juice solution. Six isolates of Ph. washingtonensis from different species of pome fruits had identical ITS sequences. The sizes of the ITS region were the same for both Ph. washingtonensis and Ph. piri, and four polymorphic nucleotide sites were found in the ITS region between Ph. washingtonensis and Ph. piri. The similarity in ITS sequences between these two taxa is confirmatory evidence for the erection of the new species of Phacidiopycnis associated with pome fruits we describe here.

Terahertz Active Photonic Crystals for Condensed Gas Sensing

PubMed Central

Benz, Alexander; Deutsch, Christoph; Brandstetter, Martin; Andrews, Aaron M.; Klang, Pavel; Detz, Hermann; Schrenk, Werner; Strasser, Gottfried; Unterrainer, Karl

2011-01-01

The terahertz (THz) spectral region, covering frequencies from 1 to 10 THz, is highly interesting for chemical sensing. The energy of rotational and vibrational transitions of molecules lies within this frequency range. Therefore, chemical fingerprints can be derived, allowing for a simple detection scheme. Here, we present an optical sensor based on active photonic crystals (PhCs), i.e., the pillars are fabricated directly from an active THz quantum-cascade laser medium. The individual pillars are pumped electrically leading to laser emission at cryogenic temperatures. There is no need to couple light into the resonant structure because the PhC itself is used as the light source. An injected gas changes the resonance condition of the PhC and thereby the laser emission frequency. We achieve an experimental frequency shift of 10−3 times the center lasing frequency. The minimum detectable refractive index change is 1.6 × 10−5 RIU. PMID:22163939

Embedded micro-sensor for monitoring pH in concrete structures

NASA Astrophysics Data System (ADS)

Srinivasan, Rengaswamy; Phillips, Terry E.; Bargeron, C. Brent; Carlson, Micah A.; Schemm, Elizabeth R.; Saffarian, Hassan M.

2000-04-01

Three major causes of corrosion of steel in concrete are chloride ions (Cl-), temperature (T) and acidity (pH). Under normal operating temperatures and with pH above 13, steel does not undergo pitting corrosion. In presence of Cl-, if the pH decreases below 12, the probability of pitting increases. Acid rain and atmospheric carbon dioxide cause the pH to drop in concrete, often leading to corrosion of the structure with the concomitant cost of repair or replacement. Currently, the pH level in concrete is estimated through destructive testing of the structures. Glass ISFET, and other pH sensors that need maintenance and calibration cannot be embedded in concrete. In this paper, we describe an inexpensive solid state pH sensor that can be embedded in concrete, to detect pH changes at the early stages. It employs a chemical reagent, trinitrobenzenesulfonic acid (TNBS) that exhibits changes in optical properties in the 12 - 14 pH range, and is held in a film of a sol-gel/TNBS composite on an optically transparent surface. A simple LED/filter/photodiode transducer monitors pH-induced changes in TNBS. Such a device needs no periodic calibration or maintenance. The optical window, the light-source and sensor can be easily housed and encapsulated in a chemically inert structure, and embedded in concrete.

Deciphering the Effect of Polymer-Assisted Doping on the Optoelectronic Properties of Block Copolymer-Anchored Graphene Oxide.

PubMed

Maity, Nabasmita; Kuila, Atanu; Nandi, Arun K

2017-02-14

Doping facilitates the tuning of band gap, providing an opportunity to tailor the optoelectronic properties of graphene in a simple way, and polymer-assisted doping is a new route to combine the optoelectronic properties of graphene with the properties of a polymer. In this endeavor, a linear diblock copolymer, polycaprolactone-block-poly(dimethyl aminoethyl methacrylate) (PCL 13 -b-PDMAEMA 117 ) (GPCLD) is grafted from the graphene oxide (GO) surface via consecutive ring opening and atom transfer radical polymerization. GPCLD is characterized using proton nuclear magnetic resonance ( 1 H NMR), Fourier transform infrared spectroscopy, atomic force microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy. The phase transition behavior of the GPCLD solution with varying temperature and pH is monitored using fluorescence spectroscopy and dynamic light scattering. Temperature-dependent 1 H NMR spectra at pH 9.2 indicate the influence of temperature on the interaction between GPCLD and solvent (water) molecules causing the phase separation. Fluorescence spectra at pH 4 and 9.2 give the evidence of localized p- and n-type doping of graphene assisted by the pendent PDMAEMA chains. In the impedance spectra of GPCLD films, the Nyquist plots vary with pH; at pH 4, they exhibit a semicircle at higher frequencies and a spike at lower frequencies; at pH 7.0, the spike is replaced by an arc; and at pH 9.2, the semicircle at higher frequencies vanishes and only a spike is noticed, all of these suggesting different types of doping of graphene at different pH values. The dc-conductivity also varies with pH and temperature because of the different types of doping. The current (I)-voltage (V) property of GPCLD at different pH values is very unique: at pH 9.2, an interesting feature of negative differential resistance (NDR) is observed; at pH 7, the rectification property is observed; and at pH 4, again the NDR property is observed. The temperature-dependent I-V property at pH 7 and 9.2 clearly indicates a signature of doping, dedoping, and redoping because of the change in the interaction of GO with the grafted polymer arising from coiling and decoiling of polymer chains.

Gold Nanoparticles Grafted with PLL-b-PNIPAM: Interplay on Thermal/pH Dual-Response and Optical Properties.

PubMed

Li, Hui-Juan; Li, Peng-Yun; Li, Li-Ying; Haleem, Abdul; He, Wei-Dong

2018-04-16

Narrowly distributed poly(l-lysine- b - N -isopropylacrylamide) (PLL- b -PNIPAM) was prepared through ring-opening polymerization of ε-benzyloxycarbonyl-l-lysine N -carboxy-α-amino anhydride and atom transfer radical polymerization of NIPAM, followed with the removal of ε-benzyloxycarbonyl group. Then gold nanoparticles (AuNPs) grafted with PLL- b -PNIPAM (PNIPAM-PLL-AuNPs) were obtained by the reduction of chloroauric acid with sodium citrate in the presence of PLL- b -PNIPAM. PNIPAM-PLL-AuNPs and its precursors were thoroughly characterized by proton magnetic resonance spectroscope, Fourier transform infrared spectroscope, UV-vis spectroscope, transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, and circular dichroism. The obtained PNIPAM-PLL-AuNPs exhibited high colloid stability even at strong alkaline (pH = 12) and acidic (pH = 2) conditions. The thermal and pH dual-responsive behaviors of the grafting PLL- b -PNIPAM chains was observed to be affected by AuNPs, while not for the secondary structure of PLL chains. Correspondingly, the surface plasmon resonance (SPR) of AuNPs was found to be sensitive to both pH value and temperature. A blue shift in the SPR happened both with increasing pH value and increasing temperature. The stimuli-response was reversible in heating-cooling cycles. The gold nanoparticles with both pH and temperature response may have potential applications in biomedical areas and biosensors.

Effect of pre-rigor stretch and various constant temperatures on the rate of post-mortem pH fall, rigor mortis and some quality traits of excised porcine biceps femoris muscle strips.

PubMed

Vada-Kovács, M

1996-01-01

Porcine biceps femoris strips of 10 cm original length were stretched by 50% and fixed within 1 hr post mortem then subjected to temperatures of 4 °, 15 ° or 36 °C until they attained their ultimate pH. Unrestrained control muscle strips, which were left to shorten freely, were similarly treated. Post-mortem metabolism (pH, R-value) and shortening were recorded; thereafter ultimate meat quality traits (pH, lightness, extraction and swelling of myofibrils) were determined. The rate of pH fall at 36 °C, as well as ATP breakdown at 36 and 4 °C, were significantly reduced by pre-rigor stretch. The relationship between R-value and pH indicated cold shortening at 4 °C. Myofibrils isolated from pre-rigor stretched muscle strips kept at 36 °C showed the most severe reduction of hydration capacity, while paleness remained below extreme values. However, pre-rigor stretched myofibrils - when stored at 4 °C - proved to be superior to shortened ones in their extractability and swelling.

Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: I. Iron-copper-zinc-lead sulfide solubility relations

USGS Publications Warehouse

Hemley, J.J.; Cygan, G.L.; Fein, J.B.; Robinson, G.R.; d'Angelo, W. M.

1992-01-01

Experimental studies, using cold-seal and extraction vessel techniques, were conducted on Fe, Pb, Zn, and Cu sulfide solubilities in chloride soultions at temperatures from 300?? to 700??C and pressures from 0.5 to 2 kbars. The solutions were buffered in pH by quartz monzonite and the pure potassium feldspar-muscovite-quartz assemblage and in fS2-fO2 largely by the assemblage pyrite-pyrrhotite-magnetite. Solubilities increase with increasing temperature and total chloride, and decrease with increasing pressure. The effect of increasing chloride concentration on solubility reflects primarily a shift to lower pH via the silicate buffer reactions. Similarity in behaviour with respect to the temperature and pressure of Fe, Zn, and Pb sulfide solubilities points to similarity in chloride speciation, and the neutral species appear to be dominant in the high-temperature region. -from Authors

Limitations and possibilities of green synthesis and long-term stability of colloidal Ag nanoparticles

NASA Astrophysics Data System (ADS)

Velgosová, Oksana; Mražíková, Anna

2017-12-01

In this paper the influence of algae life cycle and the solutions pH on the green synthesis of colloidal Ag nanoparticles (AgNPs) as well as effect of different storage conditions on AgNPs long-term stability was investigated. Silver nanoparticles were biologically synthesized using extracts of Parachlorella kessleri algae cultivated 1, 2, 3 and 4 weeks. The formation of AgNPs was monitored using a UV-vis spectrophotometer and verified by TEM observation. The results confirmed formation of polyhedron and/or near polyhedron AgNPs, ranging between 5 and 60 nm in diameter. The age of algae influenced the synthesis rate and an amount of AgNPs in solution. The best results were obtained using tree weeks old algae. UV-vis analysis and TEM observation also revealed that the size and the stability of AgNPs depend on the pH of solution. AgNPs formed in solutions of higher pH (8 and 10) are polyhedron, fine, with narrow size interval and stabile. Nanoparticles formed in solutions of low pH (2, 4 and 6) started to lose their stability on 10th day of experiment, and the particle size interval was wide. The long-term stability of AgNPs can be influenced by light and temperature conditions. The most significant stability loss was observed at day light and room temperature (21°C). After 200-days significant amount of agglomerated particles settled on the bottom of the Erlenmeyer flask. AgNPs stored at dark and room temperature showed better long-term stability, weak particles agglomeration was observed. AgNPs stored at dark and at temperature 5°C showed the best long-term stability. Such AgNPs remained spherical, fine (5-20 nm), with narrow size interval and stable (no agglomeration) even after more than six months.

Hydrogen production and metal-dye bioremoval by a Nostoc linckia strain isolated from textile mill oxidation pond.

PubMed

Mona, Sharma; Kaushik, Anubha; Kaushik, C P

2011-02-01

Biohydrogen production by Nostoc linckia HA-46, isolated from a textile-industry oxidation-pond was studied by varying light/dark period, pH, temperature and ratio of carbon-dioxide and argon in the gas-mixture. Hydrogen production rates were maximum under 18 h of light and 6 h of darkness, pH 8.0, 31°C, a CO(2):Ar ratio 2:10. Hydrogen production of the strain acclimatized to 20 mg/L of chromium/cobalt and 100 mg/L of Reactive red 198/crystal violet dye studied in N-supplemented/deficient medium was 6-10% higher in the presence of 1.5 g/L of NaNO(3). Rates of hydrogen production in the presence of dyes/metals by the strain (93-105 μmol/h/mg Chlorophyll) were significantly higher than in medium without metals/dyes serving as control (91.3 μmol/h/mg Chlorophyll). About 58-60% of the two metals and 35-73% of dyes were removed by cyanobacterium. Optimal conditions of temperature, pH and metals/dyes concentration for achieving high hydrogen production and wastewater treatment were found practically applicable as similar conditions are found in the effluent of regional textile-mills. Copyright © 2010 Elsevier Ltd. All rights reserved.

Bio-gas production from alligator weeds

NASA Technical Reports Server (NTRS)

Latif, A.

1976-01-01

Laboratory experiments were conducted to study the effect of temperature, sample preparation, reducing agents, light intensity and pH of the media, on bio-gas and methane production from the microbial anaerobic decomposition of alligator weeds (Alternanthera philoxeroides. Efforts were also made for the isolation and characterization of the methanogenic bacteria.

Paramecium: a promising non-animal bioassay to study the effect of 808 nm infrared diode laser photobiomodulation.

PubMed

Amaroli, Andrea; Parker, Steven; Dorigo, Gianluca; Benedicenti, Alberico; Benedicenti, Stefano

2015-01-01

Photobiostimulation and photobiomodulation (PBM) are terms applied to the manipulation of cellular behavior using low intensity light sources, which works on the principle of inducing a biological response through energy transfer. The aim of this investigation was to identify a laboratory assay to test the effect of an infrared diode laser light (808 nm) on cell fission rate. Sixty cells of Paramecium primaurelia were divided in two groups of 30. The first group (test group) was irradiated, at a temperature of 24°C, for 50 sec by a 808 nm diode laser with a flat top handpiece [1 cm of spot diameter, 1 W in continuous wave (CW), 50 sec irradiation time, 64 J/cm(2) of fluence]. The second group (control group) received no laser irradiation. All cells were transferred onto a depression slide, fed, and incubated in a moist chamber at a temperature of 24°C. The cells were exposed and monitored for 10 consecutive fission rates. Changes in temperature and pH were also evaluated. The exposed cells had a fission rate rhythm faster than the control cells, showing a binary fission significantly (p<0.05) shorter than unexposed cells. No significant effects of laser irradiation on pH and temperature of Paramecium's lettuce infusion medium were observed. The 808 nm infrared diode laser light, at the irradiation parameters used in our work, results in a precocious fission rate in P. primaurelia cells, probably through an increase in metabolic activity, secondary to an energy transfer.

Temperature-dependent dynamics of bovine casein micelles in the range 10-40 °C.

PubMed

Liu, Dylan Z; Weeks, Michael G; Dunstan, David E; Martin, Gregory J O

2013-12-15

Milk is a complex colloidal system that responds to changes in temperature imposed during processing. Whilst much has been learned about the effects of temperature on milk, little is known about the dynamic response of casein micelles to changes in temperature. In this study, a comprehensive physico-chemical study of casein micelles in skim milk was performed between 10 and 40 °C. When fully equilibrated, the amount of soluble casein, soluble calcium and the pH of skim milk all decreased as a function of increasing temperature, whilst the hydration and volume fraction of the casein micelles decreased. The effect of temperature on casein micelle size, as determined by dynamic light scattering and differential centrifugation, was less straightforward. Real-time measurements of turbidity and pH were used to investigate the dynamics of the system during warming and cooling of milk in the range 10-40 °C. Changes in pH are indicative of changes to the mineral system and the turbidity is a measure of alterations to the casein micelles. The pH and turbidity showed that alterations to both the casein micelles and the mineral system occurred very rapidly on warming. However, whilst mineral re-equilibration occurred very rapidly on cooling, changes to the casein micelle structure continued after 40 min of measurement, returning to equilibrium after 16 h equilibration. Casein micelle structure and the mineral system of milk were both dependent on temperature in the range 10-40 °C. The dynamic response of the mineral system to changes in temperature appeared almost instantaneous whereas equilibration of casein was considerably slower, particularly upon cooling. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stimuli-Responsive Polymer Brushes for Flow Control through Nanopores

PubMed Central

Adiga, Shashishekar P.; Brenner, Donald W.

2012-01-01

Responsive polymers attached to the inside of nano/micro-pores have attracted great interest owing to the prospect of designing flow-control devices and signal responsive delivery systems. An intriguing possibility involves functionalizing nanoporous materials with smart polymers to modulate biomolecular transport in response to pH, temperature, ionic concentration, light or electric field. These efforts open up avenues to develop smart medical devices that respond to specific physiological conditions. In this work, an overview of nanoporous materials functionalized with responsive polymers is given. Various examples of pH, temperature and solvent responsive polymers are discussed. A theoretical treatment that accounts for polymer conformational change in response to a stimulus and the associated flow-control effect is presented. PMID:24955529

Hydrogen production by a thermophilic blue-green alga Mastigocladus laminosus

NASA Astrophysics Data System (ADS)

Miura, Y.; Yokoyama, H.; Miyamoto, K.; Okazaki, M.; Komemushi, S.

Light-driven hydrogen evolution by a thermophilic blue-green alga, Mastigocladus laminosus, was demonstrated and characterized under nitrogen-starved conditions. Air-grown cultures of this alga evolved hydrogen under Ar/CO2 at rates up to 2.2 ml/mg chl/hr. The optimum temperature and pH for the hydrogen evolution were 44-49 C and pH 7.0-7.5, respectively. Evolution in light was depressed by N2 gas and inhibited by salicylaldoxime or 2,4-dinitrophenol, indicating that nitrogenase was mainly responsible for the hydrogen evolution. The evolution rate was improved by adding carbon monoxide and acetylene to the gas phase of Ar/CO2. In addition, photobiological production of hydrogen (biophotolysis) by various blue-green algae is briefly reviewed and discussed.

Structural stability of vault particles.

PubMed

Esfandiary, Reza; Kickhoefer, Valerie A; Rome, Leonard H; Joshi, Sangeeta B; Middaugh, C Russell

2009-04-01

Vaults, at 13 MDa, are the largest ribonucleoprotein particles known. In vitro, expression of the major vault protein (MVP) alone in Sf9 insect cells results in the production of recombinant particles with characteristic vault structure. With the ultimate goal of using recombinant vaults as nanocapsules for the delivery of biomolecules, we have employed a variety of spectroscopic techniques (i.e., circular dichroism, fluorescence spectroscopy, and light scattering) along with electron microscopy, to characterize the structural stability of vaults over a wide range of pH (3-8) and temperature (10-90 degrees C). Ten different conformational states of the vaults were identified over the pH and temperature range studied with the most stable region at pH 6-8 below 40 degrees C and least stable at pH 4-6 above 60 degrees C. A unique intermediate molten globulelike state was also identified at pH 6 and approximately 55 degrees C. EM imaging showed the opening of intact vaults into flowerlike structures when transitioning from neutral to acidic pH. This information has potential use in the development of recombinant vaults into nanocapsules for drug delivery since one mechanism by which therapeutic agents entrapped in vaults could be released is through an opening of the intact vault structure.

In situ Dynamics of O2, pH, Light, and Photosynthesis in Ikaite Tufa Columns (Ikka Fjord, Greenland)-A Unique Microbial Habitat.

PubMed

Trampe, Erik C L; Larsen, Jens E N; Glaring, Mikkel A; Stougaard, Peter; Kühl, Michael

2016-01-01

The Ikka Fjord (SW Greenland) harbors a unique microbial habitat in the form of several hundred submarine tufa columns composed of ikaite, a special hexahydrate form of calcium carbonate that precipitates when alkaline phosphate- and carbonate-enriched spring water seeping out of the sea floor meets cold seawater. While several unique heterotrophic microbes have been isolated from the tufa columns, the microbial activity, and the boundary conditions for microbial growth in ikaite have remained unexplored. We present the first detailed in situ characterization of the physico-chemical microenvironment and activity of oxygenic phototrophs thriving within the ikaite columns. In situ underwater microsensor measurements of pH, temperature, and irradiance in the porous ikaite crystal matrix, revealed an extreme microenvironment characterized by low temperatures, strong light attenuation, and gradients of pH changing from pH 9 at the outer column surface to above pH 10 over the first 1-2 cm of the ikaite. This outer layer of the freshly deposited ikaite matrix contained densely pigmented yellow and green zones harboring a diverse phototrophic community dominated by diatoms and cyanobacteria, respectively, as shown by amplicon sequencing. In situ O2 measurements, as well as underwater variable chlorophyll fluorescence measurements of photosynthetic activity, demonstrated high levels of oxygenic photosynthesis in this extreme gradient environment with strong irradiance-driven O2 dynamics ranging from anoxia to hyperoxic conditions in the ikaite matrix, albeit the local formation of gas bubbles buffered the day-night dynamics of O2 in the tufa columns. The microbial phototrophs in the ikaite matrix are embedded in exopolymers forming endolithic biofilms that may interact with mineral formation and cementing of ikaite crystals.

In situ Dynamics of O2, pH, Light, and Photosynthesis in Ikaite Tufa Columns (Ikka Fjord, Greenland)—A Unique Microbial Habitat

PubMed Central

Trampe, Erik C. L.; Larsen, Jens E. N.; Glaring, Mikkel A.; Stougaard, Peter; Kühl, Michael

2016-01-01

The Ikka Fjord (SW Greenland) harbors a unique microbial habitat in the form of several hundred submarine tufa columns composed of ikaite, a special hexahydrate form of calcium carbonate that precipitates when alkaline phosphate- and carbonate-enriched spring water seeping out of the sea floor meets cold seawater. While several unique heterotrophic microbes have been isolated from the tufa columns, the microbial activity, and the boundary conditions for microbial growth in ikaite have remained unexplored. We present the first detailed in situ characterization of the physico-chemical microenvironment and activity of oxygenic phototrophs thriving within the ikaite columns. In situ underwater microsensor measurements of pH, temperature, and irradiance in the porous ikaite crystal matrix, revealed an extreme microenvironment characterized by low temperatures, strong light attenuation, and gradients of pH changing from pH 9 at the outer column surface to above pH 10 over the first 1–2 cm of the ikaite. This outer layer of the freshly deposited ikaite matrix contained densely pigmented yellow and green zones harboring a diverse phototrophic community dominated by diatoms and cyanobacteria, respectively, as shown by amplicon sequencing. In situ O2 measurements, as well as underwater variable chlorophyll fluorescence measurements of photosynthetic activity, demonstrated high levels of oxygenic photosynthesis in this extreme gradient environment with strong irradiance-driven O2 dynamics ranging from anoxia to hyperoxic conditions in the ikaite matrix, albeit the local formation of gas bubbles buffered the day-night dynamics of O2 in the tufa columns. The microbial phototrophs in the ikaite matrix are embedded in exopolymers forming endolithic biofilms that may interact with mineral formation and cementing of ikaite crystals. PMID:27242741

A Water Tank Study of the Effects of Seawater Temperature on Coral Metabolism and Changes in Chemical Compositions in Seawater

NASA Astrophysics Data System (ADS)

Fujimura, H.; Arakaki, T.; Hamdun, A. M.; Oomori, T.

2002-12-01

For the past several years, large-scale coral bleaching has been observed in many coral reef areas around the world. Coral bleaching is considered to be caused mainly by high seawater temperature together with other factors such as strong UV-light and changes in salinity. However, the mechanism of coral bleaching is not clearly understood. We have conducted experiments using water tanks under well-controlled light and temperature conditions to elucidate the effects of seawater temperature on coral_fs metabolism and changes in chemical compositions in the seawater around the coral. Metabolism of coral was studied by analyzing changes in seawater chemical compositions. Coral specimen used in our experiment, Goniastrea aspera, was collected from northern shore of Okinawa island, Japan. pH, nitrate ion, dissolved organic carbon, and alkalinity were measured. Photochemically formed hydroxyl radical was also studied in those seawater samples.

Fuel neutralization by ozone oxidation

NASA Technical Reports Server (NTRS)

Swartz, A. B.; Agthe, R. E.; Smith, I. D.; Mulholland, J. P.

1988-01-01

The viability of a hazardous waste disposal system based on ozone oxidation of hydrazine fuels at low aqueous concentrations in the presence of ultraviolet light (UV at 2.537 x 10(exp -7) m or 8.324 x 10(exp -7) ft) excitation was investigated. Important parameters investigated include temperature, solution pH, and ultraviolet light power. Statistically relevant experimentation was done to estimate main factor effects on performance. The best available chemical analysis technology was used to evaluate the performance of the system.

Construction and Setup of a Bench-scale Algal Photosynthetic Bioreactor with Temperature, Light, and pH Monitoring for Kinetic Growth Tests.

PubMed

Karam, Amanda L; McMillan, Catherine C; Lai, Yi-Chun; de Los Reyes, Francis L; Sederoff, Heike W; Grunden, Amy M; Ranjithan, Ranji S; Levis, James W; Ducoste, Joel J

2017-06-14

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth parameters used in these models must be accurately determined. Algal growth experiments are often constrained by the dynamic nature of the culture environment, and control systems are needed to accurately determine the kinetic parameters. The first step in setting up a controlled batch experiment is live data acquisition and monitoring. This protocol outlines a process for the assembly and operation of a bench-scale photosynthetic bioreactor that can be used to conduct microalgal growth experiments. This protocol describes how to size and assemble a flat-plate, bench-scale PBR from acrylic. It also details how to configure a PBR with continuous pH, light, and temperature monitoring using a data acquisition and control unit, analog sensors, and open-source data acquisition software.

Construction and Setup of a Bench-scale Algal Photosynthetic Bioreactor with Temperature, Light, and pH Monitoring for Kinetic Growth Tests

PubMed Central

Karam, Amanda L.; McMillan, Catherine C.; Lai, Yi-Chun; de los Reyes, Francis L.; Sederoff, Heike W.; Grunden, Amy M.; Ranjithan, Ranji S.; Levis, James W.; Ducoste, Joel J.

2017-01-01

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth parameters used in these models must be accurately determined. Algal growth experiments are often constrained by the dynamic nature of the culture environment, and control systems are needed to accurately determine the kinetic parameters. The first step in setting up a controlled batch experiment is live data acquisition and monitoring. This protocol outlines a process for the assembly and operation of a bench-scale photosynthetic bioreactor that can be used to conduct microalgal growth experiments. This protocol describes how to size and assemble a flat-plate, bench-scale PBR from acrylic. It also details how to configure a PBR with continuous pH, light, and temperature monitoring using a data acquisition and control unit, analog sensors, and open-source data acquisition software. PMID:28654054

Influence of culture media and environmental factors on mycelial growth and pycnidial production of Sphaeropsis pyriputrescens.

PubMed

Kim, Y K; Xiao, C L; Rogers, J D

2005-01-01

Sphaeropsis pyriputrescens, the causal agent of Sphaeropsis rot of pears and apples, is a recently described species. In this study the effects of culture media, temperature, water potential, pH and light on mycelial growth and pycnidial production of S. pyriputrescens were evaluated. Apple juice agar and pear juice agar were most suitable for mycelial growth of all six isolates tested. Cornmeal agar was not suitable for either mycelial growth or pycnidial production. The fungus grew from -3 to 25 C, with optimum growth at 20 C and no growth at 30 C. The fungus grew at water potential as low as -5.6 MPa on potassium chloride-amended potato-dextrose agar (PDA). Hyphal extension was not observed at -7.3 MPa after 10 d incubation, but growth resumed when the inoculum plugs were placed on PDA. The fungus grew at pH 3.3-6.3 and optimum growth was at pH 3.3-4.2. No mycelial growth was observed at pH above 7.2 after 10 d incubation, but growth resumed when the inoculum plugs were transferred onto PDA. Regardless of medium tested, few pycnidia formed at 20 C in the dark. Pycnidial production was enhanced significantly by fluorescent light, but continuous light appeared to reduce pycnidial production, depending on the medium. Oatmeal agar (OMA) was most suitable for production of pycnidia and conidia. Pycnidia that formed on 3 wk old OMA cultures at 20 C under 12 h light/12 h dark produced abundant conidia, and the technique is recommended for inoculum production.

Influence of carcass weight on meat quality of commercial feedlot steers with similar feedlot, slaughter and post-mortem management.

PubMed

Agbeniga, Babatunde; Webb, Edward C

2018-03-01

The effects of beef carcass weight on muscle pH/temperature profile and selected meat quality attributes were evaluated. Twenty-six carcasses from light (≤260kg, n=15) and heavy (≥290kg, n=11) feedlot steers were randomly allocated and stimulated with low voltage electrical stimulation (LVES) for 30s at 7min post-mortem (pm). Quality evaluations were carried out on samples from the Longissimus et lumborum (LL) muscle from the left side of each carcass. Heavier carcasses showed faster pH decline and slower (P<0.05) temperature decline at 45min, 3, 6, 12 and 24h pm. Heavier carcasses passed through the heat shortening window (i.e. at pH6, temperature was >35°C) but there was no sign of sarcomere shortening in any carcass. Significantly lower (P<0.05) shear force values were recorded in the heavier carcasses at 3days pm but at 14days pm, heavier carcasses had numerically lower but not significantly different shear force. Heavier carcasses produced numerically higher but not significant (P>0.05) drip loss at 3 and 14days pm as well as higher L* (meat lightness) (P<0.05) and C* (chroma) (P<0.05) values early (2days) pm. However, at 14days pm, there were no significant differences between the light and heavy carcasses in terms of L* and C*. No significant difference was observed between heavy and light carcasses in terms of H* at 2 and 14days pm. The study showed that heavier carcasses which favor slaughter house pricing can be produced and processed alongside lighter carcasses without significant detrimental effects on meat quality by using low voltage electrical stimulation (LVES). Copyright © 2017 Elsevier Ltd. All rights reserved.

Introducing global peat-specific temperature and pH calibrations based on brGDGT bacterial lipids

NASA Astrophysics Data System (ADS)

Naafs, B. D. A.; Inglis, G. N.; Zheng, Y.; Amesbury, M. J.; Biester, H.; Bindler, R.; Blewett, J.; Burrows, M. A.; del Castillo Torres, D.; Chambers, F. M.; Cohen, A. D.; Evershed, R. P.; Feakins, S. J.; Gałka, M.; Gallego-Sala, A.; Gandois, L.; Gray, D. M.; Hatcher, P. G.; Honorio Coronado, E. N.; Hughes, P. D. M.; Huguet, A.; Könönen, M.; Laggoun-Défarge, F.; Lähteenoja, O.; Lamentowicz, M.; Marchant, R.; McClymont, E.; Pontevedra-Pombal, X.; Ponton, C.; Pourmand, A.; Rizzuti, A. M.; Rochefort, L.; Schellekens, J.; De Vleeschouwer, F.; Pancost, R. D.

2017-07-01

Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids from Bacteria and Archaea that are ubiquitous in a range of natural archives and especially abundant in peat. Previous work demonstrated that the distribution of bacterial branched GDGTs (brGDGTs) in mineral soils is correlated to environmental factors such as mean annual air temperature (MAAT) and soil pH. However, the influence of these parameters on brGDGT distributions in peat is largely unknown. Here we investigate the distribution of brGDGTs in 470 samples from 96 peatlands around the world with a broad mean annual air temperature (-8 to 27 °C) and pH (3-8) range and present the first peat-specific brGDGT-based temperature and pH calibrations. Our results demonstrate that the degree of cyclisation of brGDGTs in peat is positively correlated with pH, pH = 2.49 × CBTpeat + 8.07 (n = 51, R2 = 0.58, RMSE = 0.8) and the degree of methylation of brGDGTs is positively correlated with MAAT, MAATpeat (°C) = 52.18 × MBT5me‧ - 23.05 (n = 96, R2 = 0.76, RMSE = 4.7 °C). These peat-specific calibrations are distinct from the available mineral soil calibrations. In light of the error in the temperature calibration (∼4.7 °C), we urge caution in any application to reconstruct late Holocene climate variability, where the climatic signals are relatively small, and the duration of excursions could be brief. Instead, these proxies are well-suited to reconstruct large amplitude, longer-term shifts in climate such as deglacial transitions. Indeed, when applied to a peat deposit spanning the late glacial period (∼15.2 kyr), we demonstrate that MAATpeat yields absolute temperatures and relative temperature changes that are consistent with those from other proxies. In addition, the application of MAATpeat to fossil peat (i.e. lignites) has the potential to reconstruct terrestrial climate during the Cenozoic. We conclude that there is clear potential to use brGDGTs in peats and lignites to reconstruct past terrestrial climate.

Synergistic effects between TiO2 and carbon nanotubes (CNTs) in a TiO2/CNTs system under visible light irradiation.

PubMed

Wu, Chung-Hsin; Kuo, Chao-Yin; Chen, Shih-Ting

2013-01-01

This study synthesized a TiO2/carbon nanotubes (CNTs) composite via the sol-gel method. The surface characteristics of the TiO2/CNTs composite were determined by X-ray diffraction, transmission electron microscopy, specific surface area analyser, ultraviolent (UV)-vis spectroscopy, X-ray photoelectron spectroscopy and Raman spectrometer. The photocatalytic activity ofthe TiO2/CNTs composite was evaluated by decolourizing C.I. Reactive Red 2 (RR2) under visible light irradiation. Furthermore, the effects of calcination temperature, pH, RR2 concentration, and the TiO2/CNTs composite dosage on RR2 decolourization were determined simultaneously. The optimal calcination temperature to generate TiO2 and the TiO2/CNTs composite was 673 K, as the percentage of anatase crystallization at this temperature was highest. The specific surface area of the TiO2/CNTs composite and TiO2 were 45 and 42 m2/g, respectively. The band gap of TiO2 and the TiO2/CNTs composite was 2.97 and 2.71 eV by UV-vis measurements, respectively. Experimental data indicate that the Ti-O-C bond formed in the TiO2/CNTs composite. The RR2 decolourization rates can be approximated by pseudo-first-order kinetics; moreover, only the TiO2/CNTs composite had photocatalytic activity under visible light irradiation. At pH 7, the RR2 decolourization rate constant of 0.5, 1 and 2 g/L TiO2/CNTs addition was 0.005, 0.0015, and 0.0047 min(-1), respectively. Decolourization rate increased as pH and the RR2 concentration decreased. The CNTs functioned as electron acceptors, promoting separation of photoinduced electron-hole pairs to retard their recombination; thus, photocatalytic activity of the TiO2/CNTs composite exceeded that of TiO2.

Investigating the Degradation Behaviors of a Therapeutic Monoclonal Antibody Associated with pH and Buffer Species.

PubMed

Zheng, Songyan; Qiu, Difei; Adams, Monica; Li, Jinjiang; Mantri, Rao V; Gandhi, Rajesh

2017-01-01

This study aimed in understanding the degradation behaviors of an IgG 1 subtype therapeutic monoclonal antibody A (mAb-A) associated with pH and buffer species. The information obtained in this study can augment conventional, stability-based screening paradigms by providing the direction necessary for efficient experimental design. Differential scanning calorimetry (DSC) was used for studying conformational stability. Dynamic light scattering (DLS) was utilized to generate B 22 *, a modified second virial coefficient for the character of protein-protein interaction. Size-exclusion chromatography (SEC) and hydrophobic interaction chromatography (HIC) were employed to separate degradation products. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used for determining the molecular size and liquid chromatography mass spectrometry (LC-MS) were used for identifying the sequence of the separated fragments. The results showed that both pH and buffer species played the roles in controlling the degradation behaviors of mAb-A, but the pH was more significant. In particular, pH 4.5 induced additional thermal transition peaks occurring at a low temperature compared with pH 6.5. A continual temperature-stress study illustrated that the additional thermal transition peaks related to the least stable structure and a greater fragmentation. Although mAb-A showed the comparable conformational structures and an identical amount of aggregates at time zero between the different types of buffer species at pH 6.5, the aggregation formation rate showed a buffer species-dependent discrepancy over a temperature-stress period. It was found that the levels of aggregations associated with the magnitudes of protein-protein interaction forces.

Stimuli-responsive polymeric nanocarriers for the controlled transport of active compounds: concepts and applications.

PubMed

Fleige, Emanuel; Quadir, Mohiuddin A; Haag, Rainer

2012-06-15

The use of polymeric nanocarriers to transport active compounds like small-molecular drugs, peptides, or genes found an increased attention throughout the different fields of natural sciences. Not only that these nanocarriers enhance the properties of already existing drugs in terms of solubility, bioavailability, and prolonged circulation times, furthermore they can be tailor-made in such a manner that they selectively release their cargo at the desired site of action. For the triggered release, these so-called smart drug delivery systems are designed to react on certain stimuli like pH, temperature, redox potential, enzymes, light, and ultrasound. Some of these stimuli are naturally occurring in vivo, for example the difference in pH in different cellular compartments while others are caused by the disease, which is to be treated, like differences in pH and temperature in some tumor tissues. Other external applied stimuli, like light and ultrasound, allow the temporal and spatial control of the release, since they are not triggered by any biological event. This review gives a brief overview about some types of stimuli-responsive nanocarriers with the main focus on organic polymer-based systems. Furthermore, the different stimuli and the design of corresponding responsive nanocarriers will be discussed with the help of selected examples from the literature. Copyright © 2012 Elsevier B.V. All rights reserved.

Dynamic Silicon Nanophotonics

DTIC Science & Technology

2013-07-31

sensitive to fabrication imperfections and small temperature changes, therefore they are challenging to integrate into high yield mass production ... Cocoa Beach, Florida, September 2012. 15. Ali Wanis Elshaari, “Photon Manipulation in Silicon Nanophotonic Circuits,” Ph.D. Dissertation, Rochester...1.5-micron Light using Silicon Nanocrystals,” 2012 IEEE Avionics, Fiber Optics and Photonics Conference (AVFOP 2012), ThB3, Cocoa Beach, Florida

The photochemical cycle of bacteriorhodopsin

NASA Technical Reports Server (NTRS)

Lozier, R. H.; Niederberger, W.

1977-01-01

The reaction cycle of bacteriorhodopsin in the purple membrane isolated from Halobacterium halobium has been studied by optical absorption spectroscopy using low-temperature and flash kinetic techniques. After absorption of light, bacteriorhodopsin passes through at least five distinct intermediates. The temperature and pH dependence of the absorbance changes suggests that branch points and/or reversible steps exist in this cycle. Flash spectroscopy in the presence of a pH-indicating dye shows that the transient release of a proton accompanies the photoreaction cycle. The proton release occurs from the exterior and the uptake is on the cytoplasmic side of the membrane, as required by the function of bacteriorhodopsin as a light-driven proton pump. Proton translocating steps connecting release and uptake are indicated by deuterium isotope effects on the kinetics of the cycle. The rapid decay of a light-induced linear dichroism shows that a chromophore orientation change occurs during the reaction cycle.

The tunable wettability in multistimuli-responsive smart graphene surfaces

NASA Astrophysics Data System (ADS)

Wan, Shanhong; Pu, Jibin; Zhang, Xiaoqian; Wang, Liping; Xue, Qunji

2013-01-01

The tunable wettability of smart graphene films onto stainless steel substrates with a multi-response to different environmental stimuli has been investigated including light irradiation, pH, electric field, and annealing temperature. Conductive graphene film exhibited the controllable transition from water-repellent to water-loving characteristic in response to different environment fields, which primarily resulted from the morpho-chemically synergistic effect as well as the restoration of electronic stucture. Based on the fundamental theories of wettability, mechanisms in switching from hydrophobicity to hydrophilicity for smart graphene surface including thermal chemistry, electrostatic, photo-induced surface chemistry, solvent, and pH methods were presented.

Water quality of the tidal Potomac River and Estuary; hydrologic data report supplement, 1979 through 1981 water years

USGS Publications Warehouse

Coupe, R.H.; Webb, W.E.

1984-01-01

This report is a companion report to the U.S. Geological Survey 1979, 1980, and 1981 Hydrologic Data Reports of the tidal Potomac River and Estuary. It contains values of biochemical oxygen demand and specific rate constants, incident light and light attenuation measurements; numbers of phytoplankton, fecal coliform and fecal streptococci, cross-sectional averages from field measurements of dissolved oxygen, pH, specific conductance , and temperature data; and cross-sectional averages of chlorophyll data. Sewage treatment plant loads are also included. (USGS)

Scintillation properties of the silver doped lithium iodide single crystals at room and low temperature

NASA Astrophysics Data System (ADS)

Khan, Sajid; Kim, H. J.; Lee, M. H.

2016-06-01

This study presents luminescence and scintillation properties of Silver doped LiI crystals. Single crystals of LiI: x% Ag (x=0.02, 0.05, 0.1 and 0.5) were grown by using the Bridgman technique. X-ray induced luminescence spectra show emission bands spanning from 275 nm to 675 nm, dominated by Ag+ band having a peak at 300 nm. Under UV-luminescence, a similar emission band was observed with the peak excitation wavelength of 265 nm. Energy resolution, light yield and decay time profiles of the samples were measured under a 137Cs γ-ray irradiation. The LiI(0.1%Ag) showed the highest light yield and the best energy resolution among the samples. The light yield of LiI(0.1%Ag) is higher than commercially available LiI(Eu) crystal (15,000±1500 ph/MeV). The LiI(Ag) samples exhibit three exponential decay time components except the LiI(0.02%Ag), where the fitting found two decay time components. Temperature dependences of emission spectra, light yield and decay time were studied from 300 K to 10 K. The LiI(0.1%Ag) crystal showed an increase in the light yield and a shortening of decay time with a decrease in temperature..

High-performance porous spherical or octapod-like single-crystalline BiVO4 photocatalysts for the removal of phenol and methylene blue under visible-light illumination.

PubMed

Jiang, Haiyan; Meng, Xue; Dai, Hongxing; Deng, Jiguang; Liu, Yuxi; Zhang, Lei; Zhao, Zhenxuan; Zhang, Ruzhen

2012-05-30

Monoclinic BiVO(4) single-crystallites with a polyhedral, spherical or porous octapod-like morphology were selectively prepared using the triblock copolymer P123 (HO(CH(2)CH(2)O)(20)(CH(2)CH(CH(3))O)(70)(CH(2)CH(2)O)(20)H)-assisted hydrothermal method with bismuth nitrate and ammonium metavanadate as metal source and various bases as pH adjustor. The BiVO(4) materials were well characterized and their photocatalytic activities were evaluated for the removal of methylene blue (MB) and phenol in the presence of a small amount of H(2)O(2) under visible-light illumination. It is shown that the pH value of the precursor solution, surfactant, and hydrothermal temperature had an important impact on particle architecture of the BiVO(4) product. The introduction of P123 favored the generation of BiVO(4) with porous structures. The BiVO(4) derived hydrothermally with P123 at pH 3 or 6 possessed good optical absorption performance both in UV- and visible-light regions and hence showed excellent photocatalytic activities for the degradation of MB and phenol. It is concluded that the high visible-light-driven catalytic performance of the porous octapod-like BiVO(4) single-crystallites is associated with the higher surface area, porous structure, lower band gap energy, and unique particle morphology. Such porous BiVO(4) materials are useful in the solar-light-driven photocatalytic treatment of organic-containing wastewater. Copyright © 2012 Elsevier B.V. All rights reserved.

Measurements of spectral responses for developing fiber-optic pH sensor

NASA Astrophysics Data System (ADS)

Yoo, Wook Jae; Heo, Ji Yeon; Jang, Kyoung Won; Seo, Jeong Ki; Moon, Jin Soo; Park, Jang-Yeon; Park, Byung Gi; Cho, Seunghyun; Lee, Bongsoo

2011-01-01

In this study, we have fabricated a fiber-optic pH sensor, which is composed of a light source, a pH-sensing probe, plastic optical fibers and a spectrometer, for determining the degree of infection by Helicobacter pylori in the stomach. As pH indicators, phenol red and m-cresol purple are used, and pH liquid solutions are prepared by mixing phenol red or m-cresol purple solutions and various kinds of pH buffer solutions. The light emitted by a light source is guided by plastic optical fibers to the pH liquid solution, and the optical characteristic of a reflected light is changed according to the color variations of the pH indicator in the pH-sensing probe. Therefore, we have measured the intensities and wavelength shifts of the reflected lights, which change according to the color variations of indicators at different pH values, by using a spectrometer for spectral analysis. Also, the relationships between the pH values of liquid solutions and the optical properties of the modulated lights are obtained on the basis of the changes of the colors of indicators.

Switchable on/off drug release from gold nanoparticles-grafted dual light- and temperature-responsive hydrogel for controlled drug delivery.

PubMed

Amoli-Diva, Mitra; Sadighi-Bonabi, Rasoul; Pourghazi, Kamyar

2017-07-01

A switchable dual light- and temperature-responsive drug carrier using gold nanoparticles (Au NPs)-grafted poly(dimethylacrylamide-co-acrylamide)/poly acrylic acid [P(DMA-co-AAm)/PAAc] hydrogel was prepared by free radical polymerization procedure using N,N-methylenebisacrylamide as cross-linker and ammonium persulfate as initiator. Initial P(DMA-co-AAm) hydrogel and uniformly-distributed stable Au NPs, prepared by reduction of hydrogen tetrachloroaureate (III) hydrate in the presence of trisodium citrate, were synthesized separately. Then, the prepared P(DMA-co-AAm) and Au NPs were added to an acrylic acid solution along with the cross-linker and initiator to prepare PAAc hydrogel within the mixture. This improves the swelling ratio and stabilizes Au NPs in networks. Furthermore, a cross-linked P(DMA-co-AAm-co-AAc) random hydrogel was also prepared with the same monomer compositions as the above hydrogel for comparison of their properties. Then, swelling, thermal sensitivity and thermal and optical switching properties of the prepared hydrogels were investigated in two acidic (pH=1.2) and neutral (pH=7.4) buffered solutions to simulate stomach and intestine body conditions. Finally, loading and cumulative release (%) of ofloxacin antibiotic as model drug were considered in both thermal and optical switching conditions. Based on these results, pulsatile release vehicle was obtained which have the "on" state at higher temperatures and the "off" state at lower temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, J.; Walters, D. M.; Zhou, D.

Vapor-deposited glasses can be anisotropic and molecular orientation is important for organic electronics applications. In organic light emitting diodes (OLEDs), for example, the orientation of dye molecules in two-component emitting layers significantly influences emission efficiency. Here we investigate how substrate temperature during vapor deposition influences the orientation of dye molecules in a model two-component system. We determine the average orientation of a linear blue light emitter 1,4-di-[4-( N,N-diphenyl)amino]styrylbenzene (DSA-Ph) in mixtures with aluminum-tris(8-hydroxyquinoline) (Alq 3) by spectroscopic ellipsometry and IR dichroism. We find that molecular orientation is controlled by the ratio of the substrate temperature during deposition and the glassmore » transition temperature of the mixture. Furthermore, these findings extend recent results for single component vapor-deposited glasses and suggest that, during vapor deposition, surface mobility allows partial equilibration towards orientations preferred at the free surface of the equilibrium liquid.« less

Versatile Dual Photoresponsive System for Precise Control of Chemical Reactions.

PubMed

Xu, Can; Bing, Wei; Wang, Faming; Ren, Jinsong; Qu, Xiaogang

2017-08-22

A versatile method for photoregulation of chemical reactions was developed through a combination of near-infrared (NIR) and ultraviolet (UV) light sensitive materials. This regulatory effect was achieved through photoresponsive modulation of reaction temperature and pH values, two prominent factors influencing reaction kinetics. Photothermal nanomaterial graphene oxide (GO) and photobase reagent malachite green carbinol base (MGCB) were selected for temperature and pH regulation, respectively. Using nanocatalyst- and enzyme-mediated chemical reactions as model systems, we demonstrated the feasibility and high efficiency of this method. In addition, a photoresponsive, multifunctional "Band-aid"-like hydrogel platform was presented for programmable wound healing. Overall, this simple, efficient, and reversible system was found to be effective for controlling a wide variety of chemical reactions. Our work may provide a method for remote and sustainable control over chemical reactions for industrial and biomedical applications.

Substrate temperature controls molecular orientation in two-component vapor-deposited glasses

DOE PAGES

Jiang, J.; Walters, D. M.; Zhou, D.; ...

2016-02-22

Vapor-deposited glasses can be anisotropic and molecular orientation is important for organic electronics applications. In organic light emitting diodes (OLEDs), for example, the orientation of dye molecules in two-component emitting layers significantly influences emission efficiency. Here we investigate how substrate temperature during vapor deposition influences the orientation of dye molecules in a model two-component system. We determine the average orientation of a linear blue light emitter 1,4-di-[4-( N,N-diphenyl)amino]styrylbenzene (DSA-Ph) in mixtures with aluminum-tris(8-hydroxyquinoline) (Alq 3) by spectroscopic ellipsometry and IR dichroism. We find that molecular orientation is controlled by the ratio of the substrate temperature during deposition and the glassmore » transition temperature of the mixture. Furthermore, these findings extend recent results for single component vapor-deposited glasses and suggest that, during vapor deposition, surface mobility allows partial equilibration towards orientations preferred at the free surface of the equilibrium liquid.« less

Formation of tyrosine radicals in photosystem II under far-red illumination.

PubMed

Ahmadova, Nigar; Mamedov, Fikret

2018-04-01

Photosystem II (PS II) contains two redox-active tyrosine residues on the donor side at symmetrical positions to the primary donor, P 680 . Tyr Z , part of the water-oxidizing complex, is a preferential fast electron donor while Tyr D is a slow auxiliary donor to P 680 + . We used PS II membranes from spinach which were depleted of the water oxidation complex (Mn-depleted PS II) to study electron donation from both tyrosines by time-resolved EPR spectroscopy under visible and far-red continuous light and laser flash illumination. Our results show that under both illumination regimes, oxidation of Tyr D occurs via equilibrium with Tyr Z • at pH 4.7 and 6.3. At pH 8.5 direct Tyr D oxidation by P 680 + occurs in the majority of the PS II centers. Under continuous far-red light illumination these reactions were less effective but still possible. Different photochemical steps were considered to explain the far-red light-induced electron donation from tyrosines and localization of the primary electron hole (P 680 + ) on the Chl D1 in Mn-depleted PS II after the far-red light-induced charge separation at room temperature is suggested.

Reaction engineering analysis of Scenedesmus ovalternus in a flat-plate gas-lift photobioreactor.

PubMed

Koller, Anja Pia; Wolf, Lara; Weuster-Botz, Dirk

2017-02-01

Microalgal strains of the genus Scenedesmus are a promising resource for commercial biotechnological applications. The temperature-, pH- and light-dependent growth of Scenedesmus ovalternus has been investigated on a laboratory scale. Best batch process performance was obtained at 30°C, pH 8.0 and an incident photon flux density of 1300μmolphotonsm -2 s -1 using a flat-plate gas-lift photobioreactor. Highest growth rate (0.11h -1 ) and space-time yield (1.7±0.1g CDW L -1 d -1 ) were observed when applying these reaction conditions. Biomass concentrations of up to 7.5±0.1g CDW L -1 were achieved within six days (25.0±0.5g CDW m -2 d -1 ). The light-dependent growth kinetics of S. ovalternus was identified using Schuster's light transfer model and Andrews' light inhibition model (K S =545μmolphotonsm -2 s -1 ; K I =2744μmolphotonsm -2 s -1 ; μ max =0.21h -1 ). The optimal mean integral photon flux density for growth of S. ovalternus was estimated to be 1223μmolphotonsm -2 s -1 . Copyright © 2016 Elsevier Ltd. All rights reserved.

Optical pH detector based on LTCC and sol-gel technologies

NASA Astrophysics Data System (ADS)

Tadaszak, R. J.; Łukowiak, A.; Golonka, L. J.

2013-01-01

This paper presents an investigation on using sol-gel thin film as a material for sensors application in LTCC (Low Temperature Co-fired Ceramics) technology. This material gives the opportunity to make new, low-cost highly integrated optoelectronic devices. Sensors with optical detection are a significant part of these applications. They can be used for quick and safe diagnostics of some parameters. Authors present a pH detector with the optical detection system made of the LTCC material. The main part of the device is a flow channel with the chamber and sol-gel active material. The silica sol-gel with bromocresol green indicator was used. As the absorbance of sol-gel layer changes with the pH value of a measured medium, the transmitted light power was measured. The pH detector was integrated with the electronic components on the LTCC substrate.

Phototrophy in Mildly Acidic Hot Spring Ecosystems

NASA Astrophysics Data System (ADS)

Fecteau, K.; Boyd, E. S.; Shock, E.

2014-12-01

Microbial light-driven reduction of carbon in continental hydrothermal ecosystems is restricted to environments at temperatures less than 73 °C. In circumneutral and alkaline systems bacterial phototrophs (cyanobacteria and anoxygenic phototrophs) are suggested to be principally responsible for this activity whereas algal (i.e., eukaryotic) phototrophs are thought to be responsible for this activity in acidic systems. In Yellowstone National Park numerous examples of phototrophic microbial communities exist at high and low pH, while hot springs with intermediate pH (values 3-5) are rare and commonly dilute. It is thought that the transition from algal photosynthesis to bacterial photosynthesis occurs within this pH range. To test this hypothesis, we sequenced bacterial and eukaryal small subunit ribosomal RNA genes, analyzed pigments, and performed comprehensive geochemical measurements from 12 hot springs within this pH realm. At all sites, the largest phototrophic population was either comprised of Cyanobacteria or affiliated with the algal order Cyanidiales, which are ubiquitous in acidic springs, yet abundant sequences of both lineages were present in 8 of the 12 sites. Nevertheless, some of these samples exceeded the known temperature limit of the algae (56 °C), suggesting that these populations are dead or inactive. Indeed, one site yielded evidence for a large Cyanidiales population as the only phototrophs present, yet an experiment at the time of sampling failed to demonstrate light-driven carbon fixation, and analysis of extracted pigments showed a large amount of the chlorophyll degradation product pheophorbide a and very little intact chlorophyll, indicating photosynthesis occurred at this site when conditions were different. Our observations illustrate the dynamic nature of these systems that may be transiently conducive to photosynthesis, which may open niches for phototrophs of both domains and likely played a role in the evolution of photosynthesis.

Hg2+-reactive double hydrophilic block copolymer assemblies as novel multifunctional fluorescent probes with improved performance.

PubMed

Hu, Jinming; Li, Changhua; Liu, Shiyong

2010-01-19

We report on novel type of responsive double hydrophilic block copolymer (DHBC)-based multifunctional chemosensors to Hg(2+) ions, pH, and temperatures and investigate the effects of thermo-induced micellization on the detection sensitivity. Well-defined DHBCs bearing rhodamine B-based Hg(2+)-reactive moieties (RhBHA) in the thermo-responsive block, poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-RhBHA) (PEO-b-P(NIPAM-co-RhBHA)), were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Nonfluorescent RhBHA moieties are subjected to selective ring-opening reaction upon addition of Hg(2+) ions or lowering solution pH, producing highly fluorescent acyclic species. Thus, at room temperature PEO-b-P(NIPAM-co-RhBHA) DHBCs can serve as water-soluble multifunctional and efficient fluorescent chemosensors to Hg(2+) ions and pH. Upon heating above the lower critical solution temperature (approximately 36 degrees C) of the PNIPAM block, they self-assemble into micelles possessing P(NIPAM-co-RhBHA) cores and well-solvated PEO coronas, which were fully characterized by dynamic and static laser light scattering. It was found that the detection sensitivity to Hg(2+) ions and pH could be dramatically improved at elevated temperatures due to fluorescence enhancement of RhBHA residues in the acyclic form, which were embedded within hydrophobic cores of thermo-induced micellar aggregates. This work represents a proof-of-concept example of responsive DHBC-based multifunctional fluorescent chemosensors for the highly efficient detection of Hg(2+) ions, pH, and temperatures with tunable detection sensitivity. Compared to reaction-based small molecule Hg(2+) probes in previous literature reports, the integration of stimuli-responsive block copolymers with well-developed small molecule-based selective sensing moieties in the current study are expected to exhibit preferred advantages including enhanced detection sensitivity, water dispersibility, biocompatibility, facile incorporation into devices, and the ability of further functionalization for targeted imaging and detection.

Flash spectroscopy of purple membrane.

PubMed Central

Xie, A H; Nagle, J F; Lozier, R H

1987-01-01

Flash spectroscopy data were obtained for purple membrane fragments at pH 5, 7, and 9 for seven temperatures from 5 degrees to 35 degrees C, at the magic angle for actinic versus measuring beam polarizations, at fifteen wavelengths from 380 to 700 nm, and for about five decades of time from 1 microsecond to completion of the photocycle. Signal-to-noise ratios are as high as 500. Systematic errors involving beam geometries, light scattering, absorption flattening, photoselection, temperature fluctuations, partial dark adaptation of the sample, unwanted actinic effects, and cooperativity were eliminated, compensated for, or are shown to be irrelevant for the conclusions. Using nonlinear least squares techniques, all data at one temperature and one pH were fitted to sums of exponential decays, which is the form required if the system obeys conventional first-order kinetics. The rate constants obtained have well behaved Arrhenius plots. Analysis of the residual errors of the fitting shows that seven exponentials are required to fit the data to the accuracy of the noise level. PMID:3580488

Flash spectroscopy of purple membrane.

PubMed

Xie, A H; Nagle, J F; Lozier, R H

1987-04-01

Flash spectroscopy data were obtained for purple membrane fragments at pH 5, 7, and 9 for seven temperatures from 5 degrees to 35 degrees C, at the magic angle for actinic versus measuring beam polarizations, at fifteen wavelengths from 380 to 700 nm, and for about five decades of time from 1 microsecond to completion of the photocycle. Signal-to-noise ratios are as high as 500. Systematic errors involving beam geometries, light scattering, absorption flattening, photoselection, temperature fluctuations, partial dark adaptation of the sample, unwanted actinic effects, and cooperativity were eliminated, compensated for, or are shown to be irrelevant for the conclusions. Using nonlinear least squares techniques, all data at one temperature and one pH were fitted to sums of exponential decays, which is the form required if the system obeys conventional first-order kinetics. The rate constants obtained have well behaved Arrhenius plots. Analysis of the residual errors of the fitting shows that seven exponentials are required to fit the data to the accuracy of the noise level.

The Chemistry and Perception of Fluorescent White Textile Materials

NASA Astrophysics Data System (ADS)

Xu, Changhai

Cationic bleach activators (CBA) are precursors to perhydroxyl compounds that, when activated, have higher oxidation potential and potentially improved bleaching performance compared to common oxidizing agents such as hydrogen peroxide. CBAs were first reported in 1997 by Proctor & Gamble Co., and have been further developed at North Carolina State University. To date, an effective low temperature bleaching system has not been developed that offers sufficient economic improvement over existing bleaching systems. The primary purpose of this research was to develop new methods and understand key variables required for achieving enhanced whiteness of textile materials using bleach activators with or without the presence of fluorescence. A new optimized low temperature bleaching system using novel lactam-based bleach activators was developed and the effect of UV content of light sources on the whiteness of fluorescent white textile materials was evaluated. A novel class of bleach activators was synthesized by introducing benzoylcaprolactam group into a stilbene system shown as follows:* While solubility, purification and hydrolytic stability of the compounds were problematic, a new approach to low pH (pH 7-9) and low temperature (50-70°C) bleaching was found using a butyrolactam-based cationic bleach activator, N-[4-(triethylammonio methyl)benzoyl]-butyrolactam chloride (TBBC), using a central composite design (CCD) of experiment. The CCD bleaching experiments showed that cationic bleach activators are less effective with high concentrations of hydrogen peroxide in high alkaline solutions. Also a 2FI model predicted the optimized bleaching performance on 100% cotton at near neutral pH and temperatures around 50°C, in which the dosage of TBBC is the most important factor affecting the bleaching performance. This prediction was validated experimentally during bleaching of bamboo and cotton fibers. In addition, this study confirmed the hypothesis that cationic bleach activators have inherent substantivity to cellulosic fibers and that the substantivity enhances bleach effectiveness. This cationic activated bleach system was effective for cotton bleaching and the bleaching performance is superior to that of conventional peroxide bleaching. TBBC was also applied to bamboo cellulosic fibers, which exhibit excessive strength loss during conventional hot bleaching. Under optimized conditions of 5 g/L TBBC, 50°C, 30 min and pH 7.0, TBBC-based bleaching of bamboo fibers produced CIE Whiteness Index (CIE WI) values of 58.20 compared to untreated bamboo which had CIE WI values of 10.77. Hence, the TBBC bleach activator method is effective at bleaching bamboo fibers. Besides chemical bleaching, the fluorescent whitening was another approach to increase the whiteness of materials. Since the whiteness of fluorescent white materials is produced by absorbing UV light and emitting visible blue light, the UV content of light sources has a significant effect on the perception of whiteness. This research addresses the common light sources used in color matching booths. The pilot data is collected by measuring spectral radiance and spectral irradiance, which is used for analysis of the UV effect on the whiteness of fluorescent white materials. The whitening performance of a fluorescent brightening agent (FBA) is dependent on the energy and intensity of the incident UV light. No data have been reported in the open literature that shows the UV emission of standard lamps used in viewing booths. Indeed, standards pertaining to lighting do not require or recommend the standardization of the UV content in any lamps. Hence, the spectroradiometric quantification of UV emission of a series of standard viewing booths is a requirement for establishment of a methodology to determine the effect of radiometric variability in standard sources on visual perception of fluorescent white materials. The radiance measurement data collected from measuring the radiance of light sources (including daylight simulation, incandescent, horizon daylight, cool white fluorescence, and Ultralume 30) in a SpectraLight III color viewing booth and the irradiance of these light sources over a PTFE diffuse reflectance standard, AATCC textile UV calibration standard and some fluorescent whitened fabric samples showed the inadequacy of UV content of these light sources in the SpectraLight III. *Please refer to dissertation for diagram.

Recent advances in light-responsive on-demand drug-delivery systems

PubMed Central

Linsley, Chase S; Wu, Benjamin M

2017-01-01

The convergence of wearable sensors and personalized medicine enhance the ability to sense and control the drug composition and dosage, as well as location and timing of administration. To date, numerous stimuli-triggered smart drug-delivery systems have been developed to detect changes in light, pH, temperature, biomolecules, electric field, magnetic field, ultrasound and mechanical forces. This review examines the major advances within the last 5 years for the three most common light-responsive drug delivery-on-demand strategies: photochemical, photoisomerization and photothermal. Examples are highlighted to illustrate progress of each strategy in drug delivery applications, and key limitations are identified to motivate future research to advance this important field. PMID:28088880

Recent advances in light-responsive on-demand drug-delivery systems.

PubMed

Linsley, Chase S; Wu, Benjamin M

2017-02-01

The convergence of wearable sensors and personalized medicine enhance the ability to sense and control the drug composition and dosage, as well as location and timing of administration. To date, numerous stimuli-triggered smart drug-delivery systems have been developed to detect changes in light, pH, temperature, biomolecules, electric field, magnetic field, ultrasound and mechanical forces. This review examines the major advances within the last 5 years for the three most common light-responsive drug delivery-on-demand strategies: photochemical, photoisomerization and photothermal. Examples are highlighted to illustrate progress of each strategy in drug delivery applications, and key limitations are identified to motivate future research to advance this important field.

The effects of thermal and high-CO2 stresses on the metabolism and surrounding microenvironment of the coral Galaxea fascicularis.

PubMed

Agostini, Sylvain; Fujimura, Hiroyuki; Higuchi, Tomihiko; Yuyama, Ikuko; Casareto, Beatriz E; Suzuki, Yoshimi; Nakano, Yoshikatsu

2013-08-01

The effects of elevated temperature and high pCO2 on the metabolism of Galaxea fascicularis were studied with oxygen and pH microsensors. Photosynthesis and respiration rates were evaluated from the oxygen fluxes from and to the coral polyps. High-temperature alone lowered both photosynthetic and respiration rates. High pCO2 alone did not significantly affect either photosynthesis or respiration rates. Under a combination of high-temperature and high-CO2, the photosynthetic rate increased to values close to those of the controls. The same pH in the diffusion boundary layer was observed under light in both (400 and 750 ppm) CO2 treatments, but decreased significantly in the dark as a result of increased CO2. The ATP contents decreased with increasing temperature. The effects of temperature on the metabolism of corals were stronger than the effects of increased CO2. The effects of acidification were minimal without combined temperature stress. However, acidification combined with higher temperature may affect coral metabolism due to the amplification of diel variations in the microenvironment surrounding the coral and the decrease in ATP contents. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Stylophora pistillata in the Red Sea demonstrate higher GFP fluorescence under ocean acidification conditions

NASA Astrophysics Data System (ADS)

Grinblat, Mila; Fine, Maoz; Tikochinski, Yaron; Loya, Yossi

2018-03-01

Ocean acidification is thought to exert a major impact on calcifying organisms, including corals. While previous studies have reported changes in the physiological response of corals to environmental change, none have described changes in expression of the ubiquitous host pigments—fluorescent proteins (FPs)—to ocean acidification. The function of FPs in corals is controversial, with the most common consideration being that these primarily regulate the light environment in the coral tissue and protect the host from harmful UV radiation. Here, we provide for the first time experimental evidence that increased fluorescence of colonies of the coral Stylophora pistillata is independent of stress and can be regulated by a non-stressful decrease in pH. Stylophora pistillata is the most abundant and among the most resilient coral species in the northern Gulf of Eilat/Aqaba (GoE/A). Fragmented "sub-colonies" ( n = 72) incubated for 33 days under three pH treatments (ambient, 7.9, and 7.6), under ambient light, and running seawater showed no stress or adverse physiological performance, but did display significantly higher fluorescence, with lower pH. Neither the average number of planulae shed from the experimental sub-colonies nor planulae green fluorescent protein (GFP) expression changed significantly among pH treatments. Sub-colonies incubated under the lower-than-ambient pH conditions showed an increase in both total protein and GFP expression. Since extensive protein synthesis requires a high level of transcription, we suggest that GFP constitutes a UV protection mechanism against potential RNA as well as against DNA damage caused by UV exposure. Manipulating the regulation of FPs in adult corals and planulae, under controlled and combined effects of pH, light, and temperature, is crucial if we are to obtain a better understanding of the role played by this group of proteins in cnidarians.

Physiological changes induced in bacteria following pH stress as a model for space research

NASA Astrophysics Data System (ADS)

Baatout, Sarah; Leys, Natalie; Hendrickx, Larissa; Dams, Annik; Mergeay, Max

2007-02-01

The physiology of the environmental bacterium Cupriavidus metallidurans CH34 (previously Ralstonia metallidurans) is being studied in comparison to the clinical model bacterium Escherichia coli in order to understand its behaviour and resistance under extreme conditions (pH, temperature, etc.). This knowledge is of importance in the light of the potential use and interest of this strain for space biology and bioremediation. Flow cytometry provides powerful means to measure a wide range of cell characteristics in microbiological research. In order to estimate physiological changes associated with pH stress, flow cytometry was employed to estimate the extent of damage on cell size, membrane integrity and potential, and production of superoxides in the two bacterial strains. Suspensions of C. metallidurans and E. coli were submitted to a 1-h pH stress (2 to 12). For flow cytometry, fluorochromes, including propidium iodide, 3, 3'-dihexyloxacarbocyanine iodide and hydroethidine were chosen as analytical parameters for identifying the physiological state and the overall fitness of individual cells. A physiologic state of the bacterial population was assessed with a Coulter EPICS XL analyser based on the differential uptakes of these fluorescent stains. C. metallidurans cells exhibited a different staining intensity than E. coli cells. For both bacterial strains, the physiological status was only slightly affected between pH 6 and 8 in comparison with pH 7 which represents the reference pH. Moderate physiological damage could be observed at pH 4 and 5 as well as at pH 9 in both strains. At pH 2, 10 and 12, membrane permeability and potential and superoxide anion production were increased to high levels showing dramatic physiological changes. It is apparent that a range of significant physiological alterations occurs after pH stress. Fluorescent staining methods coupled with flow cytometry are useful and complementary for monitoring physiological changes induced not only by pH stress but also temperature and oxidative stress, radiation, pressure as well as space stress.

A Novel Acid-Stable Endo-Polygalacturonase from Penicillium oxalicum CZ1028: Purification, Characterization, and Application in the Beverage Industry.

PubMed

Cheng, Zhong; Chen, Dong; Lu, Bo; Wei, Yutuo; Xian, Liang; Li, Yi; Luo, Zhenzhen; Huang, Ribo

2016-06-28

Acidic endo-polygalacturonases are the major part of pectinase preparations and extensively applied in the clarification of fruits juice, vegetables extracts, and wines. However, most of the reported fungal endo-polygalacturonases are active and stable under narrow pH range and low temperatures. In this study, an acidic endo-polygalacturonase (EPG4) was purified and characterized from a mutant strain of Penicillium oxalicum. The N-terminal amino acid sequence of EPG4 (ATTCTFSGSNGAASASKSQT) was different from those of reported endopolygalacturonases. EPG4 displayed optimal pH and temperature at 5.0 and 60-70°C towards polygalacturonic acid (PGA), respectively, and was notably stable at pH 2.2-7.0. When tested against pectins, EPG4 showed enzyme activity over a broad acidic pH range (>15.0% activity at pH 2.2-6.0 towards citrus pectin; and >26.6% activity at pH 2.2-7.0 towards apple pectin). The Km and Vmax values were determined as 1.27 mg/ml and 5,504.6 U/mg, respectively. The enzyme hydrolyzed PGA in endo-manner, releasing oligo-galacturonates from PGA, as determined by TLC. Addition of EPG4 (3.6 U/ml) significantly reduced the viscosity (by 42.4%) and increased the light transmittance (by 29.5%) of the papaya pulp, and increased the recovery (by 24.4%) of the papaya extraction. All of these properties make the enzyme a potential application in the beverage industry.

Transparent ceramic scintillators for gamma spectroscopy and radiography

NASA Astrophysics Data System (ADS)

Cherepy, N. J.; Kuntz, J. D.; Seeley, Z. M.; Fisher, S. E.; Drury, O. B.; Sturm, B. W.; Hurst, T. A.; Sanner, R. D.; Roberts, J. J.; Payne, S. A.

2010-08-01

Transparent ceramics combine the scintillation performance of single crystals with the ruggedness and processability of glass. We have developed a versatile, scaleable fabrication method, wherein nanoparticle feedstock is consolidated at temperatures well below melting to form inch-scale phase-pure transparent ceramics with optical scatter of α <0.1 cm-1. We have fabricated Cerium-doped Gadolinium Garnets with light yields of ~50,000 Ph/MeV and energy resolution of <5% at 662 keV. We have also developed methods to form sheets of the high-Z ceramic scintillator, Europium-doped Lutetium Oxide Bixbyite, producing ~75,000 Ph/MeV for radiographic imaging applications.

Stability of midazolam hydrochloride injection 1-mg/mL solutions in polyvinyl chloride and polyolefin bags.

PubMed

Karlage, Kelly; Earhart, Zachary; Green-Boesen, Kelly; Myrdal, Paul B

2011-08-15

The stability of midazolam hydrochloride injection 1-mg/mL solutions in polyvinyl chloride (PVC) and polyolefin bags under varying conditions was evaluated. Triplicate solutions of midazolam hydrochloride 1-mg/mL were prepared in polyolefin and PVC i.v. bags by diluting midazolam hydrochloride injection 5 mg/mL with 5% dextrose injection. Bags were then stored under refrigeration (3-4 °C), exposed to light at room temperature (20-25 °C), or protected from light in amber bags at room temperature. Samples were taken immediately after preparation (day 0) and on days 1, 2, 3, 6, 13, 20, and 27 for analysis with a stability-indicating high-performance liquid chromatography assay in order to determine solution concentration. Stability was defined as retention of at least 90% of the initial drug concentration. The pH of each solution was also measured weekly. Sterility of the i.v. bags was determined at the end of the study by microbiological testing with culture in growth media. Differences in concentrations under the various storage conditions and bags used were analyzed using analysis of variance. All solutions retained over 98% of the initial midazolam hydrochloride concentration, with no statistically significant (p ≥ 0.05) change in concentration over the four-week period. Stability was not affected by temperature, exposure to light, or bag type. The pH of all solutions remained between 3.2 and 3.4 throughout the study. Sterility after 28 days was retained. Midazolam hydrochloride 1-mg/mL solutions diluted in 5% dextrose injection remained stable over 27 days in both polyolefin and PVC i.v. bags, regardless of storage condition.

Photoreversible absorbance changes in solutions of allophycocyanin purified from Fremyella diplosiphon: Temperature dependence and quantum efficiency

PubMed Central

Ohad, Itzakh; Clayton, Roderick K.; Bogorad, Lawrence

1979-01-01

Preparations of allophycocyanin isolated from the alga Fremyella diplosiphon show light-induced optical absorbance changes that suggest the presence of a photoconvertible component [Formula: see text] similar to the algal pigments described by J. Scheibe [(1972) Science 176, 1037-1039]. At pH < 4 the allophycocyanin has an absorption maximum at 620 nm. Red illumination causes a loss of absorbance in the red, centered at 620 nm, and subsequent green illumination restores the lost absorbance. We have studied this photoconversion at temperatures between 200 K and 307 K, analyzing the results in terms of photostationary states established under red (640 nm) and green (550 nm) light. As the temperature was lowered to 260 K, the state Pr became progressively favored; the reaction Pr → Pg induced by red light was attenuated but the reaction Pg → Pr induced by green light was not. Decreasing the temperature from 260 K to 200 K had no further effect. Two distinct and simple models can account for this curious temperature dependence. By analyzing the kinetic and steady-state data, with reasonable estimates of the molar extinction coefficients of Pr and Pg, we computed quantum efficiencies greater than 15% for the photoconversion at 300 K. We deduced that a conversion of “all Pr” to “all Pg” should produce a fractional absorbance change ΔA/A at 620 nm equal to 0.1. If the chromatic adaptation response of intact F. diplosiphon shows the unusual temperature dependence reported here, the system Pr ⇌ Pg will be implicated in mediating this response. PMID:16592721

Water quality of the tidal Potomac River and Estuary: Hydrologic Data Reports supplement, 1979 through 1981 water years

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coupe, R.H. Jr.; Webb, W.E.

1984-01-01

This report is a companion report to the US Geological Survey 1979, 1980, and 1981 Hydrologic Data Reports of the tidal Potomac River and Estuary. The information included in this report contains values of biochemical oxygen demand and specific-rate constants, incident-light and light-attenuation measurements; numbers of phytoplankton, fecal coliform and fecal streptococci; cross-sectional averages from field measurements of dissolved oxygen, pH, specific conductance, and temperature data; and cross-sectional averages of chlorophyll data. Sewage-treatment plant loads are also included. 29 refs., 4 figs., 3 tabs.

Was Ferrocyanide a Prebiotic Reagent?

NASA Technical Reports Server (NTRS)

Keefe, Anthony D.; Miller, Stanley L.

1996-01-01

Hydrogen cyanide is the starting material for a diverse array of prebiotic syntheses, including those of amino acids and purines. Hydrogen cyanide also reacts with ferrous ions to give ferrocyanide, and so it is possible that ferrocyanide was common in the early ocean. This can only be true if the hydrogen cyanide concentration was high enough and the rate of reaction of cyanide with ferrous ions was fast enough. We show experimentally that the rate of formation of ferrocyanide is rapid even at low concentrations of hydrogen cyanide in the pH range 6-8, and therefore an equilibrium calculation is valid. The equilibrium concentrations of ferrocyanide are calculated as a function of hydrogen cyanide concentration, pH and temperature. The steady state concentration of hydrogen cyanide depends on the rate of synthesis by electric discharges and ultraviolet light and the rate of hydrolysis, which depends on pH and temperature. Our conclusions show that ferrocyanide was a major species in the prebiotic ocean only at the highest production rates of hydrogen cyanide in a strongly reducing atmosphere and at temperatures of 0 C or less, although small amounts would have been present at lower hydrogen cyanide production rates. The prebiotic application of ferrocyanide as a source of hydrated electrons, as a photochemical replication process, and in semi-permeable membranes is discussed.

Inactivation of Salmonella enterica by UV-C Light Alone and in Combination with Mild Temperatures

PubMed Central

Gayán, E.; Serrano, M. J.; Raso, J.; Álvarez, I.

2012-01-01

The aim of this investigation was to study the efficacy of the combined processes of UV light and mild temperatures for the inactivation of Salmonella enterica subsp. enterica and to explore the mechanism of inactivation. The doses to inactivate the 99.99% (4D) of the initial population ranged from 18.03 (Salmonella enterica serovar Typhimurium STCC 878) to 12.75 J ml−1 (Salmonella enterica serovar Enteritidis ATCC 13076). The pH and water activity of the treatment medium did not change the UV tolerance, but it decreased exponentially by increasing the absorption coefficient. An inactivating synergistic effect was observed by applying simultaneous UV light and heat treatment (UV-H). A less synergistic effect was observed by applying UV light first and heat subsequently. UV did not damage cell envelopes, but the number of injured cells was higher after a UV-H treatment than after heating. The synergistic effect observed by combining simultaneous UV and heat treatment opens the possibility to design combined treatments for pasteurization of liquid food with high UV absorptivity, such as fruit juices. PMID:23001665

Production of starch with antioxidative activity by baking starch with organic acids.

PubMed

Miwa, Shoji; Nakamura, Megumi; Okuno, Michiko; Miyazaki, Hisako; Watanabe, Jun; Ishikawa-Takano, Yuko; Miura, Makoto; Takase, Nao; Hayakawa, Sachio; Kobayashi, Shoichi

2011-01-01

A starch ingredient with antioxidative activity, as measured by the DPPH method, was produced by baking corn starch with an organic acid; it has been named ANOX sugar (antioxidative sugar). The baking temperature and time were fixed at 170 °C and 60 min, and the organic acid used was selected from preliminary trials of various kinds of acid. The phytic acid ANOX sugar preparation showed the highest antioxidative activity, but the color of the preparation was almost black; we therefore selected L-tartaric acid which had the second highest antioxidative activity. The antioxidative activity of the L-tartaric acid ANOX sugar preparation was stable against temperature, light, and enzyme treatments (α-amylase and glucoamylase). However, the activity was not stable against variations in water content and pH value. The antioxidative activity of ANOX sugar was stabilized by treating with boiled water or nitrogen gas, or by pH adjustment.

Investigation on bandgap, diffraction, interference, and refraction effects of photonic crystal structure in GaN/InGaN LEDs for light extraction.

PubMed

Patra, Saroj Kanta; Adhikari, Sonachand; Pal, Suchandan

2014-06-20

In this paper, we have made a clear differentiation among bandgap, diffraction, interference, and refraction effects in photonic crystal structures (PhCs). For observing bandgap, diffraction, and refraction effects, PhCs are considered on the top p-GaN surface of light emitting diodes (LEDs), whereas for interference effect, hole type PhCs are considered to be embedded within n-GaN layer of LED. From analysis, it is observed that at a particular lattice periodicity, for which bandgap lies within the wavelength of interest shows a significant light extraction due to inhibition of guided mode. Beyond a certain periodicity, diffraction effect starts dominating and light extraction improves further. The interference effect is observed in embedded photonic crystal LEDs, where depth of etching supports constructive interference of outward light waves. We have also shed light on refraction effects exhibited by the PhCs and whether negative refraction properties of PhCs may be useful in case of LED light extraction.

Both Reversible Self-Association and Structural Changes Underpin Molecular Viscoelasticity of mAb Solutions.

PubMed

Sarangapani, Prasad S; Weaver, Justin; Parupudi, Arun; Besong, Tabot M D; Adams, Gary G; Harding, Stephen E; Manikwar, Prakash; Castellanos, Maria M; Bishop, Steven M; Pathak, Jai A

2016-12-01

The role of antibody structure (conformation) in solution rheology is probed. It is demonstrated here that pH-dependent changes in the tertiary structure of 2 mAb solutions lead to viscoelasticity and not merely a shear viscosity (η) increase. Steady shear flow curves on mAb solutions are reported over broad pH (3.0 ≤ pH ≤ 8.7) and concentration (2 mg/mL ≤ c ≤ 120 mg/mL) ranges to comprehensively characterize their rheology. Results are interpreted using size exclusion chromatography, differential scanning calorimetry, analytical ultracentrifugation, near-UV circular dichroism, and dynamic light scattering. Changes in tertiary structure with concentration lead to elastic yield stress and increased solution viscosity in solution of "mAb1." These findings are supported by dynamic light scattering and differential scanning calorimetry, which show increased hydrodynamic radius of mAb1 at low pH and a reduced melting temperature T m , respectively. Conversely, another molecule at 120 mg/mL solution concentration is a strong viscoelastic gel due to perturbed tertiary structure (seen in circular dichroism) at pH 3.0, but the same molecule responds as a viscous liquid due to reversible self-association at pH 7.4 (verified by analytical ultracentrifugation). Both protein-protein interactions and structural perturbations govern pH-dependent viscoelasticity of mAb solutions. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Interactions of aqueous Ag+ with fulvic acids: mechanisms of silver nanoparticle formation and investigation of stability.

PubMed

Adegboyega, Nathaniel F; Sharma, Virender K; Siskova, Karolina; Zbořil, Radek; Sohn, Mary; Schultz, Brian J; Banerjee, Sarbajit

2013-01-15

This study investigated the possible natural formation of silver nanoparticles (AgNPs) in Ag(+)-fulvic acid (FA) solutions under various environmentally relevant conditions (temperature, pH, and UV light). Increase in temperature (24-90 °C) and pH (6.1-9.0) of Ag(+)-Suwannee River fulvic acid (SRFA) solutions accelerated the appearance of the characteristic surface plasmon resonance (SPR) of AgNPs. The rate of AgNP formation via reduction of Ag(+) in the presence of different FAs (SRFA, Pahokee Peat fulvic acid, PPFA, Nordic lake fulvic acid, NLFA) and Suwannee River humic acid (SRHA) followed the order NLFA > SRHA > PPFA > SRFA. This order was found to be related to the free radical content of the acids, which was consistent with the proposed mechanism. The same order of AgNP growth was seen upon UV light illumination of Ag(+)-FA and Ag(+)-HA mixtures in moderately hard reconstituted water (MHRW). Stability studies of AgNPs, formed from the interactions of Ag(+)-SRFA, over a period of several months showed that these AgNPs were highly stable with SPR peak reductions of only ~15%. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements revealed bimodal particle size distributions of aged AgNPs. The stable AgNPs formed through the reduction of Ag(+) by fulvic and humic acid fractions of natural organic matter in the environment may be transported over significant distances and might also influence the overall bioavailability and ecotoxicity of AgNPs.

Simultaneous Determination of Oxygen and pH Inside Microfluidic Devices Using Core-Shell Nanosensors.

PubMed

Ehgartner, Josef; Strobl, Martin; Bolivar, Juan M; Rabl, Dominik; Rothbauer, Mario; Ertl, Peter; Borisov, Sergey M; Mayr, Torsten

2016-10-04

A powerful online analysis setup for the simultaneous detection of oxygen and pH is presented. It features core-shell nanosensors, which enable contactless and inexpensive read-out using adapted oxygen meters via modified dual lifetime referencing in the frequency domain (phase shift measurements). Lipophilic indicator dyes were incorporated into core-shell structured poly(styrene-block-vinylpyrrolidone) nanoparticles (average diameter = 180 nm) yielding oxygen nanosensors and pH nanosensors by applying different preparation protocols. The oxygen indicator platinum(II) meso-tetra(4-fluorophenyl) tetrabenzoporphyrin (PtTPTBPF) was entrapped into the polystyrene core (oxygen nanosensors) and a pH sensitive BF 2 -chelated tetraarylazadipyrromethene dye (aza-BODIPY) was incorporated into the polyvinylpyrrolidone shell (pH nanosensors). The brightness of the pH nanoparticles was increased by more than 3 times using a light harvesting system. The nanosensors have several advantages such as being excitable with red light, emitting in the near-infrared spectral region, showing a high stability in aqueous media even at high particle concentrations, high ionic strength, or high protein concentrations and are spectrally compatible with the used read-out device. The resolution for oxygen of the setup is 0.5-2.0 hPa (approximately 0.02-0.08 mg/L of dissolved oxygen) at low oxygen concentrations (<50 hPa) and 4-8 hPa (approximately 0.16-0.32 mg/L of dissolved oxygen) at ambient air oxygen concentrations (approximately 200 hPa at 980 mbar air pressure) at room temperature. The pH resolution is 0.03-0.1 pH units within the dynamic range (apparent pK a 7.23 ± 1.0) of the nanosensors. The sensors were used for online monitoring of pH changes during the enzymatic transformation of Penicillin G to 6-aminopenicillanic acid catalyzed by Penicillin G acylase in miniaturized stirred batch reactors or continuous flow microreactors.

Investigation of the pH-dependence of dye-doped protein-protein interactions.

PubMed

Nudelman, Roman; Gloukhikh, Ekaterina; Rekun, Antonina; Richter, Shachar

2016-11-01

Proteins can dramatically change their conformation under environmental conditions such as temperature and pH. In this context, Glycoprotein's conformational determination is challenging. This is due to the variety of domains which contain rich chemical characters existing within this complex. Here we demonstrate a new, straightforward and efficient technique that uses the pH-dependent properties of dyes-doped Pig Gastric Mucin (PGM) for predicting and controlling protein-protein interaction and conformation. We utilize the PGM as natural host matrix which is capable of dynamically changing its conformational shape and adsorbing hydrophobic and hydrophilic dyes under different pH conditions and investigate and control the fluorescent properties of these composites in solution. It is shown at various pH conditions, a large variety of light emission from these complexes such as red, green and white is obtained. This phenomenon is explained by pH-dependent protein folding and protein-protein interactions that induce different emission spectra which are mediated and controlled by means of dye-dye interactions and surrounding environment. This process is used to form the technologically challenging white light-emitting liquid or solid coating for LED devices. © 2016 The Protein Society.

Size-controllable nanopyramids photonic crystal selectively grown on p-GaN for enhanced light-extraction of light-emitting diodes.

PubMed

Du, Chengxiao; Wei, Tongbo; Zheng, Haiyang; Wang, Liancheng; Geng, Chong; Yan, Qingfeng; Wang, Junxi; Li, Jinmin

2013-10-21

Size-controllable p-GaN hexagonal nanopyramids (HnPs)-photonic crystal (PhC) structures were selectively grown on flat p-GaN layer for the elimination of total internal reflection of light-emitting diodes (LEDs). The LEDs with HnPs-PhC of 46.3% bottom fill factor (PhC lattice constant is 730 nm) showed an improved light output power by 99.9% at forward current of 350 mA compared to the reference LEDs with flat p-GaN layer. We confirmed the effect of HnPs-PhC with different bottom fill factors and the effect of nanopyramid-shaped and nanocolumn-shaped PhC on the light-extraction of LEDs was also investigated by using three-dimensional finite-difference time-domain simulations.

Capsule Design for Blue Light Therapy against Helicobacter pylori.

PubMed

Li, Zhangyong; Ren, Binbin; Tan, Haiyan; Liu, Shengrong; Wang, Wei; Pang, Yu; Lin, Jinzhao; Zeng, Chen

2016-01-01

A photo-medical capsule that emits blue light for Helicobacter pylori treatment was described in this paper. The system consists of modules for pH sensing and measuring, light-emitting diode driver circuit, radio communication and microcontroller, and power management. The system can differentiate locations by monitoring the pH values of the gastrointestinal tract, and turn on and off the blue light according to the preset range of pH values. Our experimental tests show that the capsule can operate in the effective light therapy mode for more than 32 minutes and the wireless communication module can reliably transmit the measured pH value to a receiver located outside the body.

A study of photosynthetic biogas upgrading based on a high rate algal pond under alkaline conditions: Influence of the illumination regime.

PubMed

Franco-Morgado, Mariana; Alcántara, Cynthia; Noyola, Adalberto; Muñoz, Raúl; González-Sánchez, Armando

2017-08-15

Microalgal-bacterial processes have emerged as environmental friendly systems for the cost-effective treatment of anaerobic effluents such as biogas and nutrients-laden digestates. Environmental parameters such as temperature, irradiation, nutrient concentration and pH effect the performance of the systems. In this paper, the potential of a microalgal-bacterial photobioreactor operated under high pH (≈9.5) and high alkalinity to convert biogas into biomethane was evaluated. The influence of the illumination regime (continuous light supply vs 12h/12h light/dark cycles) on the synthetic biogas upgrading efficiency, biomass productivity and nutrient removal efficiency was assessed in a High-Rate Algal Pond interconnected to a biogas absorption bubble column. No significant differences in the removal efficiency of CO 2 and H 2 S (91.5±2% and 99.5%±0.5, respectively) were recorded regardless of the illumination regime. The high fluctuations of the dissolved oxygen concentration during operation under light/dark cycles allowed to evaluate the specific growth rate and the specific partial degradation rate of the microalgae biomass by photosynthesis and respiration, respectively. The respiration reduced the net microalgae biomass productivity under light/dark cycles compared with process operation under the continuous light supply. Copyright © 2017 Elsevier B.V. All rights reserved.

The effects of moderately high temperature on zeaxanthin accumulation and decay.

PubMed

Zhang, Ru; Kramer, David M; Cruz, Jeffrey A; Struck, Kimberly R; Sharkey, Thomas D

2011-09-01

Moderately high temperature reduces photosynthetic capacities of leaves with large effects on thylakoid reactions of photosynthesis, including xanthophyll conversion in the lipid phase of the thylakoid membrane. In previous studies, we have found that leaf temperature of 40°C increased zeaxanthin accumulation in dark-adapted, intact tobacco leaves following a brief illumination, but did not change the amount of zeaxanthin in light-adatped leaves. To investigate heat effects on zeaxanthin accumulation and decay, zeaxanthin level was monitored optically in dark-adapted, intact tobacco and Arabidopsis thaliana leaves at either 23 or 40°C under 45-min illumination. Heated leaves had more zeaxanthin following 3-min light but had less or comparable amounts of zeaxanthin by the end of 45 min of illumination. Zeaxanthin accumulated faster at light initiation and decayed faster upon darkening in leaves at 40°C than leaves at 23°C, indicating that heat increased the activities of both violaxanthin de-epoxidase (VDE) and zeaxanthin epoxidase (ZE). In addition, our optical measurement demonstrated in vivo that weak light enhances zeaxanthin decay relative to darkness in intact leaves of tobacco and Arabidopsis, confirming previous observations in isolated spinach chloroplasts. However, the maximum rate of decay is similar for weak light and darkness, and we used the maximum rate of decay following darkness as a measure of the rate of ZE during steady-state light. A simulation indicated that high temperature should cause a large shift in the pH dependence of the amount of zeaxanthin in leaves because of differential effects on VDE and ZE. This allows for the reduction in ΔpH caused by heat to be offset by increased VDE activity relative to ZE.

Ultrafast Hot Carrier Dynamics in GaN and Its Impact on the Efficiency Droop.

PubMed

Jhalani, Vatsal A; Zhou, Jin-Jian; Bernardi, Marco

2017-08-09

GaN is a key material for lighting technology. Yet, the carrier transport and ultrafast dynamics that are central in GaN light-emitting devices are not completely understood. We present first-principles calculations of carrier dynamics in GaN, focusing on electron-phonon (e-ph) scattering and the cooling and nanoscale dynamics of hot carriers. We find that e-ph scattering is significantly faster for holes compared to electrons and that for hot carriers with an initial 0.5-1 eV excess energy, holes take a significantly shorter time (∼0.1 ps) to relax to the band edge compared to electrons, which take ∼1 ps. The asymmetry in the hot carrier dynamics is shown to originate from the valence band degeneracy, the heavier effective mass of holes compared to electrons, and the details of the coupling to different phonon modes in the valence and conduction bands. We show that the slow cooling of hot electrons and their long ballistic mean free paths (over 3 nm at room temperature) are a possible cause of efficiency droop in GaN light-emitting diodes. Taken together, our work sheds light on the ultrafast dynamics of hot carriers in GaN and the nanoscale origin of efficiency droop.

Algal Species and Light Microenvironment in a Low-pH, Geothermal Microbial Mat Community

PubMed Central

Ferris, M. J.; Sheehan, K. B.; Kühl, M.; Cooksey, K.; Wigglesworth-Cooksey, B.; Harvey, R.; Henson, J. M.

2005-01-01

Unicellular algae are the predominant microbial mat-forming phototrophs in the extreme environments of acidic geothermal springs. The ecology of these algae is not well known because concepts of species composition are inferred from cultivated isolates and microscopic observations, methods known to provide incomplete and inaccurate assessments of species in situ. We used sequence analysis of 18S rRNA genes PCR amplified from mat samples from different seasons and different temperatures along a thermal gradient to identify algae in an often-studied acidic (pH 2.7) geothermal creek in Yellowstone National Park. Fiber-optic microprobes were used to show that light for algal photosynthesis is attenuated to <1% over the 1-mm surface interval of the mat. Three algal sequences were detected, and each was present year-round. A Cyanidioschyzon merolae sequence was predominant at temperatures of ≥49°C. A Chlorella protothecoides var. acidicola sequence and a Paradoxia multisita-like sequence were predominant at temperatures of ≤39°C. PMID:16269755

Algal species and light microenvironment in a low-pH, geothermal microbial mat community.

PubMed

Ferris, M J; Sheehan, K B; Kühl, M; Cooksey, K; Wigglesworth-Cooksey, B; Harvey, R; Henson, J M

2005-11-01

Unicellular algae are the predominant microbial mat-forming phototrophs in the extreme environments of acidic geothermal springs. The ecology of these algae is not well known because concepts of species composition are inferred from cultivated isolates and microscopic observations, methods known to provide incomplete and inaccurate assessments of species in situ. We used sequence analysis of 18S rRNA genes PCR amplified from mat samples from different seasons and different temperatures along a thermal gradient to identify algae in an often-studied acidic (pH 2.7) geothermal creek in Yellowstone National Park. Fiber-optic microprobes were used to show that light for algal photosynthesis is attenuated to < 1% over the 1-mm surface interval of the mat. Three algal sequences were detected, and each was present year-round. A Cyanidioschyzon merolae sequence was predominant at temperatures of > or = 49 degrees C. A Chlorella protothecoides var. acidicola sequence and a Paradoxia multisita-like sequence were predominant at temperatures of < or = 39 degrees C.

The decrease of cylindrical pempek quality during boiling

NASA Astrophysics Data System (ADS)

Karneta, R.; Gultom, N. F.

2017-09-01

The research objective was to study the effects of temperature and formulation on quality of pempek lenjer during boiling. Treatments in this study were four levels of pempek formulation and five levels of temperature. Data was processed by using analysis of variance (Anova). If test results showed that samples were significantly different or highly significantly different, then further test was conducted by using Honestly Significant Different. The results showed that chemical analysis showed that fish dominant formula of cylindrical pempek had higher water content, protein content, lipid content and ash content than that of tapioca starch dominant formula, but it had lower carbohydrate content and fibre content than that of tapioca starch dominant formula.The higher the temperature at center point of cylindrical pempek, the lower the chemical quality of cylindrical pempek. The effect of formula on physical quality of cylindrical pempek showed that tapioca starch dominant formula had more rubbery texture, more neutral pH and brighter color than that of fish dominant formula.The temperature change had no significant effect on texture and pH of cylindrical pempek, but it had significant effect on lightness, intensity and chromatic color especially after exceeding optimum time of boiling.

The effect of arginine glutamate on the stability of monoclonal antibodies in solution.

PubMed

Kheddo, Priscilla; Tracka, Malgorzata; Armer, Jonathan; Dearman, Rebecca J; Uddin, Shahid; van der Walle, Christopher F; Golovanov, Alexander P

2014-10-01

Finding excipients which mitigate protein self-association and aggregation is an important task during formulation. Here, the effect of an equimolar mixture of l-Arg and l-Glu (Arg·Glu) on colloidal and conformational stability of four monoclonal antibodies (mAb1-mAb4) at different pH is explored, with the temperatures of the on-set of aggregation (Tagg) and unfolding (Tm1) measured by static light scattering and intrinsic fluorescence, respectively. Arg·Glu increased the Tagg of all four mAbs in concentration-dependent manner, especially as pH increased to neutral. Arg·Glu also increased Tm1 of the least thermally stable mAb3, but without similar direct effect on the Tm1 of other mAbs. Raising pH itself from 5 to 7 increased Tm1 for all four mAbs. Selected mAb formulations were assessed under accelerated stability conditions for the monomer fraction remaining in solution after storage. The aggregation of mAb3 was suppressed to a greater extent by Arg·Glu than by Arg·HCl. Furthermore, Arg·Glu suppressed the aggregation of mAb1 at neutral pH such that the fraction monomer was near to that at the more typical formulation pH of 5.5. We conclude that Arg·Glu can suppress mAb aggregation with increasing temperature/pH and, importantly, under accelerated stability conditions at weakly acidic to neutral pH. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

pH- and thermo-responsive microcontainers as potential drug delivery systems: Morphological characteristic, release and cytotoxicity studies.

PubMed

Efthimiadou, Eleni K; Tapeinos, Christos; Tziveleka, Leto-Aikaterini; Boukos, Nikos; Kordas, George

2014-04-01

Polymeric pH- and thermo-sensitive microcontainers (MCs) were developed as a potential drug delivery system for cancer therapy. It is well known that cancer cells exhibit notable characteristics such as acidic pH due to glycolytic cycle and higher temperature due to their higher proliferation rate. Based on these characteristics, we constructed a dual pH- and thermo-sensitive material for specific drug release on the pathological tissue. The MC's fabrication is based on a two-step procedure, in which, the first step involves the core synthesis and the second one is related to the shell formation. The core consists of poly(methyl methacrylate (PMMA), while the shell consists of PMMA, poly(isopropylacrylamide), poly(acrylic acid) and poly(divinylbenzene). Three different types of MCs were synthesized based on the seed polymerization method. The synthesized MCs were characterized structurally by Fourier transform infrared and morphologically by scanning electron microscopy. Dynamic light scattering was also used to study their behavior in aqueous solution under different pH and temperature conditions. For the loading and release study, the anthracycline drug daunorubicin (DNR) was used as a model drug, and its release properties were evaluated under different pH and thermo-conditions. Cytotoxicity studies were also carried out against MCF-7 breast cancer and 3T3 mouse embryonic fibroblast cells. According to our results, the synthesized microcontainers present desired pH and thermo behavior and can be applied in drug delivery systems. It is worth mentioning that the synthesized microcontainers which incorporated the drug DNR exhibit higher toxicity than the free drug. Copyright © 2014 Elsevier B.V. All rights reserved.

Rapid Synthesis of Silver Nanoparticles from Fusarium oxysporum by Optimizing Physicocultural Conditions

PubMed Central

Birla, Sonal S.; Gaikwad, Swapnil C.; Gade, Aniket K.; Rai, Mahendra K.

2013-01-01

Synthesis of silver nanoparticles (SNPs) by fungi is emerging as an important branch of nanotechnology due to its ecofriendly, safe, and cost-effective nature. In order to increase the yield of biosynthesized SNPs of desired shape and size, it is necessary to control the cultural and physical parameters during the synthesis. We report optimum synthesis of SNPs on malt extract glucose yeast extract peptone (MGYP) medium at pH 9–11, 40–60°C, and 190.7 Lux and in sun light. The salt concentrations, volume of filtrate and biomass quantity were found to be directly proportional to the yield. The optimized conditions for the stable and rapid synthesis will help in large scale synthesis of monodispersed SNPs. The main aim of the present study was to optimize different media, temperature, pH, light intensity, salt concentration, volume of filtrate, and biomass quantity for the synthesis of SNPs by Fusarium oxysporum. PMID:24222751

pH-dependent Differential Scanning Calorimetry and Dynamic Light Scattering Studies of 21:0 PC and 18:0 PS Lipid Binary System

NASA Astrophysics Data System (ADS)

Ali, Rejwan

2010-03-01

Large unilamallar vesicle has been a model system to study many membrane functions. High Tg lipid systems offer many potential biomedical applications in lipid-based delivery applications. While the optimized vesicle functionalities are achieved by Polyethylene Glycol (PEG) polymer, modified PEG and other functional molecule incorporation, however, the host binary lipid system plays the pivotal role in pH-dependent phase transition based lipid vehicular methods. We have investigated a lipid binary system composed of 21:0 PC (1,2-dihenarachidoyl-sn-glycero-3-phosphocholine) and 18:0 PS(1,2-distearoyl-sn-glycero-3-phospho-L-serine). Preliminary studies implementing differential scanning calorimetry shows pH plays key role in temperature shift and thermotropic phase behavior of the binary system. While dynamic light scattering study shows lipid vesicle size is almost independent of pH changes. We will also present pH-dependent thermodynamic parameters to correlate underlying molecular mechanism in relevant pH-range.

Effect of marination on CIE L* and pH values of chicken breast pectoralis major with different color lightness

USDA-ARS?s Scientific Manuscript database

Color lightness (CIE L* values) and pH are widely used as quality indicators for raw poultry breast fillets (pectoralis major). The objective of this study was to evaluate the effects of vacuum-tumbling marination on L* and pH values of raw chicken breast meat with different color lightness. Early d...

Effect of marination on CIE L* and pH values of chicken breast pectoralis major with different color lightness

USDA-ARS?s Scientific Manuscript database

Color lightness (CIE L* values) and pH are widely used as quality indicators for raw poultry breast fillets (pectoralis major). The objective of this study was to evaluate the effects of vacuum-tumbling marination on L* and pH values of raw chicken breast meat with different color lightness. Early ...

The multi-mode polarization modulation spectrometer: part 1: simultaneous detection of absorption, turbidity, and optical activity.

PubMed

Arvinte, Tudor; Bui, Tam T T; Dahab, Ali A; Demeule, Barthélemy; Drake, Alex F; Elhag, Dhia; King, Peter

2004-09-01

Circular dichroism (CD) is an important spectroscopic technique for monitoring chirality and biological macromolecule conformation. However, during a CD measurement, absorbance, light scattering/turbidity, and fluorescence can also be detected. The simultaneous measurement of these different spectral features for a single sample is the basis of a multi-mode optical spectrometer. This allows time-efficient gathering of complementary information and provides a scheme to ensure that CD measurements are reliable. Aspects of circular polarization differential light scattering, pH, and temperature variation of a protein (antibody) solution are described. A procedure to help ensure that CD measurements are reliable is described.

Role of hydrous iron oxide formation in attenuation and diel cycling of dissolved trace metals in a stream affected by acid rock drainage

USGS Publications Warehouse

Parker, S.R.; Gammons, C.H.; Jones, Clain A.; Nimick, D.A.

2007-01-01

Mining-impacted streams have been shown to undergo diel (24-h) fluctuations in concentrations of major and trace elements. Fisher Creek in south-central Montana, USA receives acid rock drainage (ARD) from natural and mining-related sources. A previous diel field study found substantial changes in dissolved metal concentrations at three sites with differing pH regimes during a 24-h period in August 2002. The current work discusses follow-up field sampling of Fisher Creek as well as field and laboratory experiments that examine in greater detail the underlying processes involved in the observed diel concentration changes. The field experiments employed in-stream chambers that were either transparent or opaque to light, filled with stream water and sediment (cobbles coated with hydrous Fe and Al oxides), and placed in the stream to maintain the same temperature. Three sets of laboratory experiments were performed: (1) equilibration of a Cu(II) and Zn(II) containing solution with Fisher Creek stream sediment at pH 6.9 and different temperatures; (2) titration of Fisher Creek water from pH 3.1 to 7 under four different isothermal conditions; and (3) analysis of the effects of temperature on the interaction of an Fe(II) containing solution with Fisher Creek stream sediment under non-oxidizing conditions. Results of these studies are consistent with a model in which Cu, Fe(II), and to a lesser extent Zn, are adsorbed or co-precipitated with hydrous Fe and Al oxides as the pH of Fisher Creek increases from 5.3 to 7.0. The extent of metal attenuation is strongly temperature-dependent, being more pronounced in warm vs. cold water. Furthermore, the sorption/co-precipitation process is shown to be irreversible; once the Cu, Zn, and Fe(II) are removed from solution in warm water, a decrease in temperature does not release the metals back to the water column. ?? 2006 Springer Science+Business Media B.V.

Calorimetric and Diffractometric Evidence for the Sequential Crystallization of Buffer Components and the Consequential pH Swing in Frozen Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundaramurthi, Prakash; Shalaev, Evgenyi; Suryanarayanan, Raj

2010-06-22

Sequential crystallization of succinate buffer components in the frozen solution has been studied by differential scanning calorimetry and X-ray diffractometry (both laboratory and synchrotron sources). The consequential pH shifts were monitored using a low-temperature electrode. When a solution buffered to pH < pK{sub a2} was cooled from room temperature (RT), the freeze-concentrate pH first increased and then decreased. This was attributed to the sequential crystallization of succinic acid, monosodium succinate, and finally disodium succinate. When buffered to pH > pK{sub a2}, the freeze-concentrate pH first decreased and then increased due to the sequential crystallization of the basic (disodium succinate) followedmore » by the acidic (monosodium succinate and succinic acid) buffer components. XRD provided direct evidence of the crystallization events in the frozen buffer solutions, including the formation of disodium succinate hexahydrate [Na{sub 2}(CH{sub 2}COO){sub 2} {center_dot} 6H{sub 2}O]. When the frozen solution was warmed in a differential scanning calorimeter, multiple endotherms attributable to the melting of buffer components and ice were observed. When the frozen solutions were dried under reduced pressure, ice sublimation was followed by dehydration of the crystalline hexahydrate to a poorly crystalline anhydrate. However, crystalline succinic acid and monosodium succinate were retained in the final lyophiles. The pH and the buffer salt concentration of the prelyo solution influenced the crystalline salt content in the final lyophile. The direction and magnitude of the pH shift in the frozen solution depended on both the initial pH and the buffer concentration. In light of the pH-sensitive nature of a significant fraction of pharmaceuticals (especially proteins), extreme care is needed in both the buffer selection and its concentration.« less

[Influence of LDAO on the conformation and release of bacteriochlorophyll of peripheral light-harvesting complex (LH2) from Rhodobacter azotoformans].

PubMed

Zhao, Gen-gui; Dong, Yan-min; Yang, Su-ping; Jiao, Nian-zhi; Qu, Yin-bo

2010-10-01

The aim of this study is to reveal the interaction relationships between lauryl dimethylamine N-oxide (LDAO) and peripheral light-harvesting complex (LH2) as well as the influence of LDAO on structure and function of LH2. In the present work, the effects of LDAO on the conformation and release processes of bacteriochlorophyll (BChl) of LH2 when incubated under different temperature and pH in the presence and absence of LDAO were investigated by spectroscopy. The results indicated that (1) the presence of LDAO resulted in alterations in the conformation, alpha-helix content, and spectra of Tyr and B850 band of LH2 at room temperature and pH 8.0. Moreover, energy transfer efficiency of LH2 was enhanced markedly in the presence of LDAO. (2) At 60 degrees C, both the B800 and B850 band of LH2 were released and transited into free BChl at pH 8.0. However, the release rates of bacteriochlorophylls of B800 and B850 band from LH2 were slowed down and the release processes were changed when incubated in the presence of LDAO. Hence, the stability of LH2 was improved in the presence of LDAO. (3) The accelerated release processes of bacteriochlorophylls of B800 and B850 band of LH2 were induced to transform into bacteriopheophytin (BPhe) and free BChl by LDAO in strong acid and strong alkalic solution at room temperature. However, the kinetic patterns of the B800 and B850 band were remarkably different. The release and self-assemble processes of B850 in LH2 were observed in strong acid solution without LDAO. Therefore, the different release behaviors of B800 and B850 of LH2 are induced by LDAO under different extreme environmental conditions.

Distribution of cultivated and uncultivated cyanobacteria and Chloroflexus-like bacteria in hot spring microbial mats

NASA Technical Reports Server (NTRS)

Ruff-Roberts, A. L.; Kuenen, J. G.; Ward, D. M.

1994-01-01

Oligodeoxynucleotide hybridization probes were developed to complement specific regions of the small subunit (SSU) rRNA sequences of cultivated and uncultivated cyanobacteria and Chloroflexus-like bacteria, which inhabit hot spring microbial mats. The probes were used to investigate the natural distribution of SSU rRNAs from these species in mats of Yellowstone hot springs of different temperatures and pHs as well as changes in SSU rRNA distribution resulting from 1-week in situ shifts in temperature, pH, and light intensity. Synechococcus lividus Y-7c-s SSU rRNA was detected only in the mat of a slightly acid spring, from which it may have been initially isolated, or when samples from a more alkaline spring were incubated in the more acid spring. Chloroflexus aurantiacus Y-400-fl SSU rRNA was detected only in a high-temperature mat sample from the alkaline Octopus Spring or when lower-temperature samples from this mat were incubated at the high-temperature site. SSU rRNAs of uncultivated species were more widely distributed. Temperature distributions and responses to in situ temperature shifts suggested that some of the uncultivated cyanobacteria might be adapted to high-, moderate-, and low-temperature ranges whereas an uncultivated Chloroflexus-like bacterium appears to have broad temperature tolerance. SSU rRNAs of all uncultivated species inhabiting a 48 to 51 degrees C Octopus Spring mat site were most abundant in the upper 1 mm and were not detected below a 2.5-to 3.5-mm depth, a finding consistent with their possible phototrophic nature. However, the effects of light intensity reduction on these SSU rRNAs were variable, indicating the difficulty of demonstrating a phototrophic phenotype in light reduction experiments.

Spatial patterns of soil pH and the factors that influence them in plantation forests of northern China

NASA Astrophysics Data System (ADS)

Hong, Songbai; Liu, Yongwen; Piao, Shilong

2017-04-01

Climate and anthropogenic activities such as afforestation and nitrogen deposition all impact soil pH. Understanding the spatial pattern of soil pH and the factors that influence it can provide basic information for generating appropriate strategies for soil resource management and protection, especially in light of increasing anthropogenic influences and climate change. In this study, we investigated the spatial and vertical pattern of soil pH and evaluated the influence of climate and nitrogen deposition using 1647 soil profiles 1 meter in depth from 549 plots in plantation forests of northern China. We found that soil pH decreased from the southwest to the northeast in the study region and had a similar spatial pattern before and after afforestation. Furthermore, our results show that climate and nitrogen deposition fundamentally influence the pattern of soil pH. Specifically, increasing precipitation significantly decreased soil pH (with a mean rate of 0.3 for every 100 mm rainfall, p<0.001), whereas increasing temperature significantly increased soil pH (0.13 for every degree centigrade, p<0.001). Nitrogen deposition, especially nitrate nitrogen, significantly decreased soil pH (p<0.01). All these factors impact soil pH directly and indirectly through climate-plant-soil interactions. As the risks from both climate change and nitrogen deposition increase, there is an urgent need to further understanding of soil pH dynamics and to develop informed policies to protect soil resources.

Self-assembly behavior of pH- and thermosensitive amphiphilic triblock copolymers in solution: experimental studies and self-consistent field theory simulations.

PubMed

Cai, Chunhua; Zhang, Liangshun; Lin, Jiaping; Wang, Liquan

2008-10-09

We investigated, both experimentally and theoretically, the self-assembly behaviors of pH- and thermosensitive poly(L-glutamic acid)- b-poly(propylene oxide)-b-poly(L-glutamic acid) (PLGA-b-PPO-b-PLGA) triblock copolymers in aqueous solution by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), circular dichroism (CD), and self-consistent field theory (SCFT) simulations. Vesicles were observed when the hydrophilic PLGA block length is shorter or the pH value of solution is lower. The vesicles were found to transform to spherical micelles when the PLGA block length increases or its conformation changes from helix to coil with increasing the pH value. In addition, increasing temperature gives rise to a decrease in the size of aggregates, which is related to the dehydration of the PPO segments at higher temperatures. The SCFT simulation results show that the vesicles transform to the spherical micelles with increasing the fraction or statistical length of A block in model ABA triblock copolymer, which corresponds to the increase in the PLGA length or its conformation change from helix to coil in experiments, respectively. The SCFT calculations also provide chain distribution information in the aggregates. On the basis of both experimental and SCFT results, the mechanism of the structure change of the PLGA- b-PPO- b-PLGA aggregates was proposed.

An experimental study on ferrous iron photo-oxidation: Effect of the solar spectrum on the surface for acidification of surface water in the early Hesperian Mars

NASA Astrophysics Data System (ADS)

Tabata, H.; Sekine, Y.; Kanzaki, Y.; Sugita, S.; Murakami, T.

2017-12-01

Geochemical evidence obatined by Mars Opportunity rover suggests that the pH of Martian surface water shifted to highly acidic, i.e., pH 2-4, in the early Hesperian (e.g., Tosca et al., 2005). Hurowitz et al. (2010) proposed that solar UV light may have promoted the acidification through photo-oxidation of ferrous iron dissolved in upwelling groundwater on early Mars. However, the trigger for the acidification in the early Hesperian remains unclear. The photo-oxidation of Fe2+ occurs under acidic conditions, i.e., pH < 3 (Jortner et al., 1962); however, the pH of upwelling groundwater would be neutral to alkaline (Zolotov et al., 2016). At neutral to alkaline pH, FeOH+ can exist together with Fe2+ in a solution. While both Fe2+ and FeOH+ are photo-oxidized only by UV light (< 300 nm), FeOH+ can also be photo-oxidized by long UV/visible light (300-400 nm). Thus, the efficiency of acidification through photo-oxidation on early Mars should have depended on the solar spectrum on the surface at that time which is determined by the atmospheric composition. To investigate the effect of UV spectrum on the acidification, we conducted two types of laboratory experiments: One used a Xe lamp as the light source for photo-oxidation of ferrous iron to irradiate light with continuous spectrum from 250 to 400 nm, and the other used the Xe lamp with an optical filter that cuts off UV light shorter than 300 nm. The pH value of the starting solution was around 7. Upon the UV irradiation covering full wavelength range (250-400 nm), the pH value of the solution decreases down to less than 4, consistent with the proposed pH of the Hesperian acidic water on Meridiani Planum (Tosca et al., 2005). This occurs because Fe2+ is stable at pH < 5, and because Fe2+ can be continuously photo-oxidized in the acidic solution by UV light in 250-300 nm. When the UV irradiation covering 300-400 nm, the pH value of the solution also decreases to pH 5 immediately after the UV irradiation. However, it does not decrease less than pH 5 and reaches a steady state. This is the case because FeOH+ is converted into Fe2+ at low pH, which prevents further photo-oxidation by light in 300-400 nm. These results suggest that a change in the atmospheric composition and consequent reaching of UV light in the wavelength < 300 nm may have played a key role for triggering the acidification in the early Hesperian.

Physicochemical parameters optimization, and purification of phycobiliproteins from the isolated Nostoc sp.

PubMed

Johnson, Eldin M; Kumar, Kanhaiya; Das, Debabrata

2014-08-01

The present study investigated the effects of several physicochemical parameters on the improvement of phycobiliproteins (especially phycocyanin) synthesis in a newly isolated species of Nostoc sp. Standard BG11₀ medium was modified to enhance the biomass productivity in different photobioreactors. The initial pH of 8, light intensity of 40 μmol m(-2)s(-1), temperature of 35 °C, diurnal cycle of 16:8 h (light:dark regime), 75.48 μM Na₂CO₃ and 17.65 mM NaNO₃ were found most suitable for the phycobiliproteins synthesis. Cyanobacteria exhibited chromatic adaptation, causing overexpression of phycocyanin in red and phycoerythrin in green light. The maximum phycobiliproteins yield of 0.13 gg(-1) dry cell weight was obtained in green light. Phycocyanin was further purified using thin layer chromatography (TLC), anion exchange chromatography and SDS-PAGE (denaturing gel) electrophoresis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Seawater Acidification and Elevated Temperature Affect Gene Expression Patterns of the Pearl Oyster Pinctada fucata

PubMed Central

Liu, Wenguang; Huang, Xiande; Lin, Jianshi; He, Maoxian

2012-01-01

Oceanic uptake of anthropogenic carbon dioxide results in decrease in seawater pH and increase in temperature. In this study, we demonstrated the synergistic effects of elevated seawater temperature and declined seawater pH on gene expression patterns of aspein, calmodulin, nacrein, she-7-F10 and hsp70 in the pearl oyster Pinctada fucata. Under ‘business-as-usual’ scenarios, four treatments were examined: (1) ambient pH (8.10) and ambient temperature (27°C) (control condition), (2) ambient pH and elevated temperature (+3°C), (3) declined pH (7.70) and ambient temperature, (4) declined pH and elevated temperature. The results showed that under warming and acidic seawater conditions, expression of aspein and calmodulin showed no significant differences among different time point in condition 8.10 T. But the levels of aspein and calmodulin in conditions 8.10 T+3, 7.70 T and 7.70 T+3, and levels of nacrein, she-7-F10 in all the four treatments changed significantly. Low pH and pH×temperature interaction influenced the expression of aspein and calmodulin significantly after hours 48 and 96. Significant effects of low pH and pH×temperature interaction on the expression of nacrein were observed at hour 96. The expression level of she-7-F10 was affected significantly by pH after hours 48 and 96. The expression of hsp70 was significantly affected by temperature, pH, temperature×pH interaction at hour 6, and by temperature×pH interaction at hour 24. This study suggested that declined pH and pH×temperature interaction induced down regulation of calcification related genes, and the interaction between declined seawater pH and elevated temperature caused up regulation of hsp70 in P. facata. These results demonstrate that the declined seawater pH and elevated temperature will impact the physiological process, and potentially the adaptability of P. fucata to future warming and acidified ocean. PMID:22438983

Mussel shells of Mytilus edulis as bioarchives of the distribution of rare earth elements and yttrium in seawater and the potential impact of pH and temperature on their partitioning behavior

NASA Astrophysics Data System (ADS)

Ponnurangam, A.; Bau, M.; Brenner, M.; Koschinsky, A.

2016-02-01

Mussel shells are potential bioarchives of proxies for changes in the physicochemical conditions in the bivalve's habitat. One such proxy is the distribution of rare earths and yttrium (REY) in seawater, as REY speciation in seawater is sensitive to pH and temperature variations, due to the impact of these parameters on the activity of CO32- in seawater. We present a new protocol for sample preparation and determination of ultratrace concentrations of REY in bulk bivalve shells (comprised of calcite and aragonite) that includes sample treatment with NaOCl followed by REY separation and preconcentration. The data obtained were used to calculate REY partition coefficients between bulk bimineralic shells of Mytilus edulis (calcite aragonite mix) and ambient seawater, and the results acquired were then used to investigate the potential effects of pH and temperature on REY partitioning.Shells of Mytilus edulis mussels from the North Sea show consistent shale-normalized (SN) REY patterns that increase from the light REY to the middle REY and decrease from the middle REY to the heavy REY. Despite being different from the general seawater REYSN pattern, the shells still display distinct REY features of seawater, such as a negative CeSN anomaly and small positive YSN and GdSN anomalies. Apparent REY partition coefficients between shells and seawater (appDTot.REYshell/seawater) are low and decrease strongly from the light REY (4.04 for La) to the heavy REY (0.34 for Lu). However, assuming that only the free REY3+ are incorporated into the shell, modDFreeREY3+shell/seawater values are higher and comparatively similar for all REY (102.46 for La; 113.44 for Lu) but show a slight maximum at Tb (199.18). Although the impact of vital effects, such as REY speciation in a mussel's extrapallial fluid from which the carbonate minerals precipitate, cannot be quantified yet, it appears that M. edulis shells are bioarchives of some REY features of seawater.We modeled the REYSN patterns of a hypothetical mussel shell at pH 8.2 and 7.6 and at temperatures of 25 and 5 °C, assuming that only free REY3+ are incorporated into the carbonate's crystal lattice and that vital effects do not obliterate the REY signal of the shells. The results suggest that with lower pH, REY concentrations in shells increase, but with little effect on the shape of the REYSN patterns, while a temperature change has an impact on the REYSN pattern but only minor effects on REY concentrations. Hence, after additional calibration studies, the REY systematics in mussel shells may become a valuable proxy for paleo-pH and ocean acidification.

Demonstration of a stabilized alumina/ethanol colloidal dispersion technique for seeding high temperature air flows

NASA Technical Reports Server (NTRS)

Wernet, Mark P.; Skoch, Gary J.; Wernet, Judith H.

1995-01-01

Laser anemometry enables the measurement of complex flow fields via the light scattered from small particles entrained in the flow. In the study of turbomachinery, refractory seed materials are required for seeding the flow due to the high temperatures encountered. In this work we present a pH stabilization technique commonly employed in ceramic processing to obtain stable dispersions for generating aerosols of refractory seed material. By adding submicron alumina particles to a preadjusted pH solution of ethanol, a stable dispersion is obtained which when atomized, produces a high quality aerosol. Commercial grade alumina powder is used with a moderate size distribution. Other metal oxide powders in various polar solvents could also be used once the point of zero charge (pH(pzc)) of the powder in the solvent has been determined. Laser anemometry measurements obtained using the new seeding technique are compared to measurements obtained using Polystyrene Latex (PSL) spheres as the seed material.

Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: II. Some general geologic applications

USGS Publications Warehouse

Hemley, J.J.; Hunt, J.P.

1992-01-01

The experimental metal solubilities for rock-buffered hydrothermal systems provide important insights into the acquisition, transport, and deposition of metals in real hydrothermal systems that produced base metal ore deposits. Water-rock reactions that determine pH, together with total chloride and changes in temperature and fluid pressure, play significant roles in controlling the solubility of metals and determining where metals are fixed to form ore deposits. Deposition of metals in hydrothermal systems occurs where changes such as cooling, pH increase due to rock alteration, boiling, or fluid mixing cause the aqueous metal concentration to exceed saturation. Metal zoning results from deposition occurring at successive saturation surfaces. Zoning is not a reflection simply of relative solubility but of the manner of intersection of transport concentration paths with those surfaces. Saturation surfaces will tend to migrate outward and inward in prograde and retrograde time, respectively, controlled by either temperature or chemical variables. -from Authors

Struvite Crystallization of Anaerobic Digestive Fluid of Swine Manure Containing Highly Concentrated Nitrogen

PubMed Central

Lee, Eun Young; Oh, Min Hwan; Yang, Seung-Hak; Yoon, Tae Han

2015-01-01

In this study, the optimal operation factors for struvite crystallization for removing and recovering nitrogen and phosphorus from anaerobic digestive fluid of swine manure containing highly concentrated nitrogen was determined. Every experiment for the struvite crystallization reaction was conducted by placing 1,000 mL of digestion fluid in a 2,000 mL Erlenmeyer flask at various temperatures, pH, and mixing speed. Except for special circumstances, the digestion fluid was centrifuged (10,000 rpm, 10 min) and then the supernatant was used for the experiment at room temperature and 100 rpm. The optimal mole ratio of PO43−:Mg2+ was 1:1.5, and the pH effect ranging from 9 to 11 was similar, when mixed for 1 hour. Under this condition, the removal efficiency of NH4+-N and PO43−-P was 40% and 88.6%, respectively. X-shaped crystal was observed by light and scanning electron microscopy. In addition, struvite crystal structure was confirmed through X-ray diffraction analysis. PMID:26104412

CO2-induced ocean acidification does not affect individual or group behaviour in a temperate damselfish.

PubMed

Kwan, Garfield Tsz; Hamilton, Trevor James; Tresguerres, Martin

2017-07-01

Open ocean surface CO 2 levels are projected to reach approximately 800 µatm, and ocean pH to decrease by approximately 0.3 units by the year 2100 due to anthropogenic CO 2 emissions and the subsequent process of ocean acidification (OA). When exposed to these CO 2 /pH values, several fish species display abnormal behaviour in laboratory tests, an effect proposed to be linked to altered neuronal GABA A- receptor function. Juvenile blacksmith ( Chromis punctipinnis ) are social fish that regularly experience CO 2 /pH fluctuations through kelp forest diurnal primary production and upwelling events, so we hypothesized that they might be resilient to OA. Blacksmiths were exposed to control conditions (pH ∼ 7.92; p CO 2  ∼ 540 µatm), constant acidification (pH ∼ 7.71; p CO 2  ∼ 921 µatm) and oscillating acidification (pH ∼ 7.91, p CO 2  ∼ 560 µatm (day), pH ∼ 7.70, p CO 2  ∼ 955 µatm (night)), and caught and tested in two seasons of the year when the ocean temperature was different: winter (16.5 ± 0.1°C) and summer (23.1 ± 0.1°C). Neither constant nor oscillating CO 2 -induced acidification affected blacksmith individual light/dark preference, inter-individual distance in a shoal or the shoal's response to a novel object, suggesting that blacksmiths are tolerant to projected future OA conditions. However, blacksmiths tested during the winter demonstrated significantly higher dark preference in the individual light/dark preference test, thus confirming season and/or water temperature as relevant factors to consider in behavioural tests.

The relationship of physical and chemical conditions of CEP diluent with egg yolk addition to bull spermatozoa quality before and after storage at temperaturof 4-5°C

NASA Astrophysics Data System (ADS)

Ducha, N.; Hariani, D.; Budijastuti, W.

2018-01-01

Storage of semen requires diluent to dilute semen and maintain sperm quality. One of the diluent for bull semen was CEP. The purpose of this study was to assess the association of bull spermatozoa quality with the physical and chemical conditions of CEP diluents with the addition of egg yolk before and after the storage process. The study used Limousin bull with 5 replications. The quality of spermatozoa included motility and viability. Physical and chemical conditions included the pH and osmolarity of the diluent. The motility of spermatozoa was observed under a light microscope with 200 X magnification at 37°C by two people. The viability of spermatozoa was observed under a light microscope with 400 X magnification with nigrosine eosin staining. Data were analyzed with ANOVA and continued Duncan’s test. Dilution pH was measured using pH indicator paper ranging from 6-8. The osmolarity of the diluent was measured by electrical osmolarity. The results showed that the addition of egg yolk in the CEP diluent decreased the pH and increased osmolartitas, but the quality of spermatozoa can be kept up to 8 days of storage. The conclusion in this study was the addition of egg yolk in the CEP diluent provided physical and chemical conditions that can maintain the quality of spermatozoa during storage at a temperature of 4-5 ° C.

Inactivation of the novel avian influenza A (H7N9) virus under physical conditions or chemical agents treatment.

PubMed

Zou, Shumei; Guo, Junfeng; Gao, Rongbao; Dong, Libo; Zhou, Jianfang; Zhang, Ye; Dong, Jie; Bo, Hong; Qin, Kun; Shu, Yuelong

2013-09-15

In the spring of 2013, a novel avian-origin influenza A (H7N9) virus in Eastern China emerged causing human infections. Concerns that a new influenza pandemic could occur were raised. The potential effect of chemical agents and physical conditions on inactivation of the novel avian influenza H7N9 virus had not been assessed. To determine the inactivation effectiveness of the novel avian influenza A (H7N9) virus under various physical conditions and chemical treatments, two H7N9 viruses A/Anhui/1/2013 and A/Shanghai/1/2013 were treated by varied temperatures, ultraviolet light, varied pHs and different disinfectants. The viruses with 107.7 EID50 were exposed to physical conditions (temperature, ultraviolet light and pH) or treated with commercial chemical agents (Sodium Hypochlorite, Virkon®-S, and Ethanol) respectively. After these treatments, the viruses were inoculated in SPF embryonated chicken eggs, the allantoic fluid was collected after 72-96 hours culture at 35°C and tested by haemagglutination assay. Both of the tested viruses could tolerate conditions under 56°C for 15 minutes or 60°C for 5 minutes, but their infectivity was completely lost under 56°C for 30 minutes, 65°C for 10 minutes, 70°C, 75°C and 100°C for 1 minute. It was also observed that the H7N9 viruses lost their infectivity totally after exposure of ultraviolet light irradiation for 30 minutes or longer time. Additionally, the viruses were completely inactivated at pH less than 2 for 0.5 hour or pH 3 for 24 hours, however, viruses remained infectious under pH treatment of 4-12 for 24 hours. The viruses were totally disinfected when treated with Sodium Hypochlorite, Virkon®-S and Ethanol at recommended concentrations after only 5 minutes. The novel avian influenza A (H7N9) virus can be inactivated under some physical conditions or with chemical treatments, but they present high tolerance to moderately acidic or higher alkali conditions. The results provided the essential information for public health intervention of novel H7N9 avian influenza outbreak.

Dynamics of proteins: Light scattering study of dilute and dense colloidal suspensions of eye lens homogenates

NASA Astrophysics Data System (ADS)

Giannopoulou, A.; Aletras, A. J.; Pharmakakis, N.; Papatheodorou, G. N.; Yannopoulos, S. N.

2007-11-01

We report a dynamic light scattering study on protein suspensions of bovine lens homogenates at conditions (pH and ionic strength) similar to the physiological ones. Light scattering data were collected at two temperatures, 20 and 37°C, over a wide range of concentrations from the very dilute limit up to the dense regime approaching the physiological lens concentration. A comparison with experimental data from intact bovine lenses was advanced, revealing differences between dispersions and lenses at similar concentrations. In the dilute regime, two scattering entities were detected and identified with the long-time self-diffusion modes of α-crystallins and their aggregates, which naturally exist in lens nucleus. Upon increasing protein concentration, significant changes in time correlation function were observed starting at ˜75mgml-1, where a new mode originating from collective diffusive motions becomes visible. Self-diffusion coefficients are temperature insensitive, whereas the collective diffusion coefficient depends strongly on temperature revealing a reduction of the net repulsive interparticle forces with decreasing temperature. While there are no rigorous theoretical approaches on particle diffusion properties for multicomponent, nonideal hard sphere polydispersed systems, as the suspensions studied here, a discussion of the volume fraction dependence of the long-time self-diffusion coefficient in the context of existing theoretical approaches was undertaken. This study is purported to provide some insight into the complex light scattering pattern of intact lenses and the interactions between the constituent proteins that are responsible for lens transparency. This would lead to understand basic mechanisms of specific protein interactions that lead to lens opacification (cataract) under pathological conditions.

Processed dairy beverages pH evaluation: consequences of temperature variation.

PubMed

Ferreira, Fabiana Vargas; Pozzobon, Roselaine Terezinha

2009-01-01

This study assessed the pH from processed dairy beverages as well as eventual consequences deriving from different ingestion temperatures. 50 adults who accompanied children attended to at the Dentistry School were randomly selected and they answered a questionnaire on beverages. The beverages were divided into 4 groups: yogurt (GI) fermented milk (GII), chocolate-based products (GIII) and fermented dairy beverages (GIV). They were asked which type, flavor and temperature. The most popular beverages were selected, and these made up the sample. A pH meter Quimis 400A device was used to verify pH. The average pH from each beverage was calculated and submitted to statistical analysis (Variance and Tukey test with a 5% significance level). for groups I, II and III beverages, type x temperature interaction was significant, showing the pH averages were influenced by temperature variation. At iced temperatures, they presented lower pH values, which were considered statistically significant when compared to the values found for the same beverages at room temperature. All dairy beverages, with the exception of the chocolate-based type presented pH below critical level for enamel and present corrosive potential; as to ingestion temperature, iced temperature influenced pH reducing its values, in vitro.

Factors controlling induction of reproduction in algae--review: the text.

PubMed

Agrawal, S C

2012-09-01

This review surveys on the influence of different environmental factors like light (intensity, quality, photoperiod), temperature, season, nutrients (inorganic, organic), biotic factors (algal extracellular products, bacterial association, animals grazing), osmotic stress, pH of the medium, wave motion and mechanical shock, pollution, and radiations (UV, X-rays, gamma radiation) on the induction (or inhibition) of algal reproduction like cell division in unicellular algae, and formation of zoospores, aplanospores, akinetes, cysts, antheridia, oogonia, zygospores, etc.

Interaction of Tryptophane and Phenylalanine with Cadmium and Molybdenum Ferrocyanides and Its Implications in Chemical Evolution and Origins of Life.

NASA Astrophysics Data System (ADS)

Tewari, Brij

2016-07-01

Insoluble metal hexacyanoferrate(II) complexes could have concentrated biomonomers from dilute prebiotic soup during course of chemical evolution and origin of life or primitive earth. In the light of above hypothesis, adsorption of tryptophane and phenylalanine was studied on cadmium and molybdenum ferrocyanides at neutral pH (7.0 ± 0.01) and at a temperature of 30 ± 1º C. Interaction of amino acids with metal ferrocyanides are found to be maximum at neutral pH. Neutral pH is chosen for the adsorption studies because most of the reactions in biological systems taken place at neutral pH range. Adsorption trend follow Langmuir isotherm model. The Langmuir constants b and Qo were calculated at neutral pH, tryptophane was found to more adsorbed than phenylalanine on both metal ferrocyanides studied. Molybdenum ferrocyanides studied. Molybdenum ferrocyanides was found to have more uptake capacity for both adsorbates than cadmium ferrocyanides. The present study suggests that metal ferrocyanides might have played a role in the stabilization of biomolecules through their surface activity during course of chemical solution and origins of life on primitive earth.

Preparation of dual-stimuli-responsive liposomes using methacrylate-based copolymers with pH and temperature sensitivities for precisely controlled release.

PubMed

Sugimoto, Takumi; Yamazaki, Naoko; Hayashi, Takaaki; Yuba, Eiji; Harada, Atsushi; Kotaka, Aki; Shinde, Chiharu; Kumei, Takayuki; Sumida, Yasushi; Fukushima, Mitsuhiro; Munekata, Yuki; Maruyama, Keiichi; Kono, Kenji

2017-07-01

Dual-signal-sensitive copolymers were synthesized by copolymerization of methoxy diethylene glycol methacrylate, methacrylic acid, and lauroxy tetraethylene glycol methacrylate, which respectively provide temperature sensitivity, pH sensitivity, and anchoring to liposome surfaces. These novel copolymers, with water solubility that differs depending on temperature and pH, are soluble in water under neutral pH and low-temperature conditions, but they become water-insoluble and form aggregates under acidic pH and high-temperature conditions. Liposomes modified with these copolymers exhibited enhanced content release at weakly acidic pH with increasing temperature, although no temperature-dependent content release was observed in neutral conditions. Interaction between the copolymers and the lipid monolayer at the air-water interface revealed that the copolymer chains penetrate more deeply into the monolayer with increasing temperature at acidic pH than at neutral pH, where the penetration of copolymer chains was moderate and temperature-independent at neutral pH. Interaction of the copolymer-modified liposomes with HeLa cells demonstrated that the copolymer-modified liposomes were adsorbed quickly and efficiently onto the cell surface and that they were internalized more gradually than the unmodified liposomes through endocytosis. Furthermore, the copolymer-modified liposomes enhanced the content release in endosomes with increasing temperature, but no such temperature-dependent enhancement of content release was observed for unmodified liposomes. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Elevated CO2 and Decreased Dissolved Oxygen on Phototactic Behaviors of Juvenile Dungeness Crab (Cancer magister)

NASA Astrophysics Data System (ADS)

Imm, J.

2015-12-01

Anthropogenic CO2 emissions are increasing the concentration of CO2 in the oceans, and contributing to ocean acidification (OA), while increasing ocean temperatures and eutrophication are causing decreased levels of dissolved oxygen (DO). Due to coastal upwelling and limited water flow, the Puget Sound ecosystem is naturally high in CO2 and seasonally low in DO, making it particularly susceptible to increased acidification and hypoxia. Dungeness crabs (Cancer magister) are both ecologically and economically important to the Puget Sound region. To investigate the threat of low pH and DO to C. magister behavior, megalopae and juveniles were exposed to current and predicted future levels of pH and DO. Juveniles were then placed in a dark container with a single bright light, and movement and phototaxis were studied during three-minute trials. We hypothesized that low pH and low DO conditions would alter phototactic behaviors of juvenile C. magister, through changes in neurotransmission and metabolism. C. magister reared in control (High pH-High DO) conditions spent a greater proportion of their time near the light, and were significantly more likely to touch the light during the three-minute trial, as compared to juveniles in the other treatment conditions. These results suggest that future predicted CO2 and DO conditions in Puget Sound could disrupt the behavioral and cognitive abilities of juvenile crabs, leading to decreased survival and recruitment in the C. magister population. Given the importance of C. magister to the Puget Sound, these population changes could have significant ecological and economic implications for the region.

Effects of Elevated CO2 and Decreased Dissolved Oxygen on Phototactic Behaviors of Juvenile Dungeness Crab (Cancer magister)

NASA Astrophysics Data System (ADS)

Imm, J.

2016-02-01

Anthropogenic CO2 emissions are increasing the concentration of CO2 in the oceans, and contributing to ocean acidification (OA), while increasing ocean temperatures and eutrophication are causing decreased levels of dissolved oxygen (DO). Due to coastal upwelling and limited water flow, the Puget Sound ecosystem is naturally high in CO2 and seasonally low in DO, making it particularly susceptible to increased acidification and hypoxia. Dungeness crabs (Cancer magister) are both ecologically and economically important to the Puget Sound region. To investigate the threat of low pH and DO to C. magister behavior, megalopae and juveniles were exposed to current and predicted future levels of pH and DO. Juveniles were then placed in a dark container with a single bright light, and movement and phototaxis were studied during three-minute trials. We hypothesized that low pH and low DO conditions would alter phototactic behaviors of juvenile C. magister, through changes in neurotransmission and metabolism. C. magister reared in control (High pH-High DO) conditions spent a greater proportion of their time near the light, and were significantly more likely to touch the light during the three-minute trial, as compared to juveniles in the other treatment conditions. These results suggest that future predicted CO2 and DO conditions in Puget Sound could disrupt the behavioral and cognitive abilities of juvenile crabs, leading to decreased survival and recruitment in the C. magister population. Given the importance of C. magister to the Puget Sound, these population changes could have significant ecological and economic implications for the region.

Assembly properties of the Bacillus subtilis actin, MreB.

PubMed

Mayer, Joshua A; Amann, Kurt J

2009-02-01

The bacterial actin MreB has been implicated in a variety of cellular roles including cell shape determination, cell wall synthesis, chromosome condensation and segregation, and the establishment and maintenance of cell polarity. Toward elucidating a clearer understanding of how MreB functions inside the bacterial cell, we investigated biochemically the polymerization of MreB from Bacillus subtilis. Light scattering and sedimentation assays revealed pH-, ionic-, cationic-, and temperature-dependent behavior. B. subtilis MreB polymerizes in the presence of millimolar divalent cations in a protein concentration-dependent manner. Polymerization is favored by decreasing pH and inhibited by monovalent salts and low temperatures. Although B. subtilis MreB binds and hydrolyzes both ATP and GTP, it does not require a bound nucleotide for assembly and polymerizes indistinguishably regardless of the nucleotide species bound, with a critical concentration of approximately 900 nM. A number of the presently reported properties of B. subtilis MreB differ significantly from those of T. maritima MreB1 (Bean and Amann [2008]: Biochemistry 47: 826-835), including the nucleotide requirements and temperature and ionic effects on polymerization state. These observations collectively suggest that additional factors interact with MreB to account for its complex dynamic behavior in cells.

Pork Quality Traits According to Postmortem pH and Temperature in Berkshire

PubMed Central

Kim, Tae Wan; Kim, Chul Wook; Yang, Mi Ra; No, Gun Ryoung; Kim, Il-Suk

2016-01-01

This study was performed to investigate the role of pH and temperature postmortem, and to demonstrate the importance of these factors in determining meat quality. Postmortem pH45min (pH at 45 min postmortem or initial pH) via analysis of Pearson’s correlation showed high positive correlation with pH change pHc24 (pH change from pH45min to pH24h postmortem). However, postmortem pH after 24 h (pH24h or ultimate pH) had a high negative correlation with pH change, pHc24, CIE L*, and protein content. Initial temperature postmortem (T1h ) was positively associated with a change in temperature from 45 min to 24 h postmortem (Tc24) and cooking loss, but negatively correlated with water holding capacity. Temperature at 24 h postmortem (T24h) was negatively associated with Tc24. Collectively, these results indicate that higher initial pH was associated with higher pHc24, T1h, and Tc24. However, higher initial pH was associated with a reduction in carcass weight, backfat thickness, CIE a* and b*, water holding capacity, collagen and fat content, drip loss, and cooking loss as well as decreased shear force. In contrast, CIE a* and b*, drip loss, cooking loss, and shear force in higher ultimate pH was showed by a similar pattern to higher initial pH, whereas pHc24, carcass weight, backfat thickness, water holding capacity, fat content, moisture content, protein content, T1h, T24h, and Tc24 were exhibited by completely differential patterns (p<0.05). Therefore, we suggest that initial pH, ultimate pH, and temperatures postmortem are important factors in determining the meat quality of pork. PMID:27499661

Functional and rheological properties of proteins in frozen turkey breast meat with different ultimate pH.

PubMed

Chan, J T Y; Omana, D A; Betti, M

2011-05-01

Functional and rheological properties of proteins from frozen turkey breast meat with different ultimate pH at 24 h postmortem (pH(24)) have been studied. Sixteen breast fillets from Hybrid Tom turkeys were initially selected based on lightness (L*) values for each color group (pale, normal, and dark), with a total of 48 breast fillets. Further selection of 8 breast samples was made within each class of meat according to the pH(24). The average L* and pH values of the samples were within the following range: pale (L* >52; pH ≤5.7), normal (46 < L* < 52; 5.9 < pH <6.1), and dark (L* <46; pH ≥6.3), referred to as low, normal, and high pH meat, respectively. Ultimate pH did not cause major changes in the emulsifying and foaming properties of the extracted sarcoplasmic and myofibrillar proteins. An SDS-PAGE profile of proteins from low and normal pH meat was similar, which revealed that the extent of protein denaturation was the same. Low pH meat had the lowest water-holding capacity compared with normal and high pH meat as shown by the increase in cooking loss, which can be explained by factors other than protein denaturation. Gel strength analysis and folding test revealed that gel-forming ability was better for high pH meat compared with low and normal pH meat.Dynamic viscoelastic behavior showed that myosin denaturation temperature was independent of pH(24). Normal and high pH meat had similar hardness, springiness, and chewiness values as revealed by texture profile analysis. The results from this study indicate that high pH meat had similar or better functional properties than normal pH meat. Therefore, high pH meat is suitable for further processed products, whereas low pH meat may need additional treatment or ingredient formulations to improve its functionality.

Aggregation-induced emission: phenomenon, mechanism and applications.

PubMed

Hong, Yuning; Lam, Jacky W Y; Tang, Ben Zhong

2009-08-07

It is textbook knowledge that chromophore aggregation generally quenches light emission. In this feature article, we give an account on how we observed an opposite phenomenon termed aggregation-induced emission (AIE) and identified the restriction of intramolecular rotation as a main cause for the AIE effect. Based on the mechanistic understanding, we developed a series of new fluorescent and phosphorescent AIE systems with emission colours covering the entire visible spectral region and luminescence quantum yields up to unity. We explored high-tech applications of the AIE luminogens as, for example, fluorescence sensors (for explosive, ion, pH, temperature, viscosity, pressure, etc.), biological probes (for protein, DNA, RNA, sugar, phospholipid, etc.), immunoassay markers, PAGE visualization agents, polarized light emitters, monitors for layer-by-layer assembly, reporters for micelle formation, multistimuli-responsive nanomaterials, and active layers in the fabrication of organic light-emitting diodes.

Investigation of pH response and photo-control of wettability on spiropyran-derivatized surfaces

NASA Astrophysics Data System (ADS)

Park, Choong-Do

2009-12-01

One promising method to control a liquid drop on a surface for microfluidic devices is to use the surface tension gradient on a photo-responsive surface by light irradiation. A photo-switchable spiropyran monolayer was prepared on smooth glass or silicon wafers via 3-aminopropylmethyldiethoxysilane linkages. The pH response of the surface-bound spiropyran was investigated by measuring contact angle as a function of pH, since the pH value of the liquids applied to a microfluidic system can vary widely. Based on the contact angle titration and UV-Vis spectroscopic data, a protonation and deprotonation mechanism of the surface-bound spiropyran was proposed. The advancing contact angles under UV and under visible light irradiation at high pH values were about 100 smaller than those at low pH values. The decrease in contact angle under UV light with decreasing pH value was assigned to the protonation of open merocyanine (MC) to MC-OH+. Meanwhile, the decrease in contact angle under visible light was attributed to the protonation of the closed spiropryan (SP), generating a mixed state of MC-OH+ in equilibrium with N-protonated SP-NH+. In order to examine the possibility of light-induced liquid drop motion on the spiropyran-derivatized smooth surfaces, the light-induced surface tension change between SP and MC was estimated using the contact angle hysteresis (CAH) and the Lifshitz---van der Waals/Acid-Base (LWAB) approaches based on the contact angle data. The average light-induced surface energy change between the two isomers under UV and visible light exposure was 1.4 mJ/m 2, implying that the small change in surface tension is not sufficient to move a liquid droplet on the surface. Liquid drop motion requires that the light-induced switching angle be greater than the contact angle hysteresis. However, the light-induced switching angle of the spiropyran-derivatized surface was significantly smaller than the hysteresis. Thus, in order to achieve liquid drop motion on the spiropyran-derivatized surface, a new surface design which employs a combination of chemical modification of a hydrophobic organosilane and micropatterned rough surface morphology was suggested.

Caged ATP - an internal calibration method for ATP bioluminescence assays.

PubMed

Calvert, R M; Hopkins, H C; Reilly, M J; Forsythe, S J

2000-03-01

ATP bioluminescence, based on the firefly luciferase system, is used for the rapid determination of hygienic practices in the food industry. This study has demonstrated the use of caged ATP as an internal ATP standard and quantified the effects of industrial cleansing solutions, alcoholic beverages and pH on firefly luciferase activity. The light signal was quenched 6-47% by five cleansing solutions at standard working concentrations. Ethanol at 1% (v/v) inhibited bioluminescence by 15% (w/v) whereas concentrations above 4% enhanced the light output. The light signal was quenched by 20-25% at pH values below pH 4 and above pH 10.

A proteorhodopsin-based biohybrid light-powering pH sensor.

PubMed

Rao, Siyuan; Guo, Zhibin; Liang, Dawei; Chen, Deliang; Wei, Yen; Xiang, Yan

2013-10-14

The biohybrid sensor is an emerging technique for multi-functional detection that utilizes the instinctive responses or interactions of biomolecules. We develop a biohybrid pH sensor by taking advantage of the pH-dependent photoelectric characteristics of proteorhodopsin (pR). The transient absorption kinetics study indicates that the photoelectric behavior of pR is attributed to the varying lifetime of the M intermediate at different environmental pH values. This pR-based biohybrid light-powering sensor with microfluidic design can achieve real-time pH detection with quick response and high sensitivity. The results of this work would shed light on pR and its potential applications.

Monitoring the Erosion of Hydrolytically-Degradable Nanogels via Multiangle Light Scattering Coupled to Asymmetrical Flow Field-Flow Fractionation

PubMed Central

Smith, Michael H.; South, Antoinette B.; Gaulding, Jeffrey C.; Lyon, L. Andrew

2009-01-01

We describe the synthesis and characterization of degradable nanogels that display bulk erosion under physiologic conditions (pH = 7.4, 37 °C). Erodible poly(N-isopropylmethacrylamide) nanogels were synthesized by copolymerization with N,O-(dimethacryloyl)hydroxylamine, a cross-linker previously used in the preparation of non-toxic and biodegradable bulk hydrogels. To monitor particle degradation, we employed multiangle light scattering and differential refractometry detection following asymmetrical flow field-flow fractionation. This approach allowed the detection of changes in nanogel molar mass and topology as a function of both temperature and pH. Particle erosion was evident from both an increase in nanogel swelling and a decrease in scattering intensity as a function of time. Following these analyses, the samples were recovered for subsequent characterization by direct particle tracking, which yields hydrodynamic size measurements and enables number density determination. Additionally, we confirmed the conservation of nanogel stimuli-responsivity through turbidity measurements. Thus, we have demonstrated the synthesis of degradable nanogels that erode under conditions and on timescales that are relevant for many drug delivery applications. The combined separation and light scattering detection method is demonstrated to be a versatile means to monitor erosion and should also find applicability in the characterization of other degradable particle constructs. PMID:20000662

Polymeric micelles with stimuli-triggering systems for advanced cancer drug targeting.

PubMed

Nakayama, Masamichi; Akimoto, Jun; Okano, Teruo

2014-08-01

Since the 1990s, nanoscale drug carriers have played a pivotal role in cancer chemotherapy, acting through passive drug delivery mechanisms and subsequent pharmaceutical action at tumor tissues with reduction of adverse effects. Polymeric micelles, as supramolecular assemblies of amphiphilic polymers, have been considerably developed as promising drug carrier candidates, and a number of clinical studies of anticancer drug-loaded polymeric micelle carriers for cancer chemotherapy applications are now in progress. However, these systems still face several issues; at present, the simultaneous control of target-selective delivery and release of incorporated drugs remains difficult. To resolve these points, the introduction of stimuli-responsive mechanisms to drug carrier systems is believed to be a promising approach to provide better solutions for future tumor drug targeting strategies. As possible trigger signals, biological acidic pH, light, heating/cooling and ultrasound actively play significant roles in signal-triggering drug release and carrier interaction with target cells. This review article summarizes several molecular designs for stimuli-responsive polymeric micelles in response to variation of pH, light and temperature and discusses their potentials as next-generation tumor drug targeting systems.

Purification and characterization of tannin acyl hydrolase produced by mixed solid state fermentation of wheat bran and marigold flower by Penicillium notatum NCIM 923.

PubMed

Gayen, Saswati; Ghosh, Uma

2013-01-01

Tannin acyl hydrolase produced extracellularly by the fungal strain Penicillium notatum NCIM 923 in mixed solid state fermentation of wheat bran and marigold flower in the ratio 4 : 1 was purified from the cell-free extract broth by ammonium sulphate fractionation followed by diethylaminoethyl-cellulose column chromatography. Tannase was purified by 19.89-fold with yield of 11.77%. The specific activity of crude tannase was found to be 1.31 U/mg protein while that of purified tannase was 22.48 U/mg protein. SDS-PAGE analysis indicated that the enzyme is dimeric with one major band of molecular mass 97 kDa and a very light band of molecular mass 43 kDa. Temperature of 35 to 40°C and pH 5 were optimum for tannase activity. The enzyme retained more than 60% of its stability at 60°C and 40% stability at pH 3 and 8, respectively. K m was found to be 0.33 × 10(-2) M and V max = 40 U/mg. Since the enzyme is active over a wide range of pH and temperature, it could find potential use in the food processing industry.

Purification and Characterization of Tannin Acyl Hydrolase Produced by Mixed Solid State Fermentation of Wheat Bran and Marigold Flower by Penicillium notatum NCIM 923

PubMed Central

Gayen, Saswati; Ghosh, Uma

2013-01-01

Tannin acyl hydrolase produced extracellularly by the fungal strain Penicillium notatum NCIM 923 in mixed solid state fermentation of wheat bran and marigold flower in the ratio 4 : 1 was purified from the cell-free extract broth by ammonium sulphate fractionation followed by diethylaminoethyl-cellulose column chromatography. Tannase was purified by 19.89-fold with yield of 11.77%. The specific activity of crude tannase was found to be 1.31 U/mg protein while that of purified tannase was 22.48 U/mg protein. SDS-PAGE analysis indicated that the enzyme is dimeric with one major band of molecular mass 97 kDa and a very light band of molecular mass 43 kDa. Temperature of 35 to 40°C and pH 5 were optimum for tannase activity. The enzyme retained more than 60% of its stability at 60°C and 40% stability at pH 3 and 8, respectively. K m was found to be 0.33 × 10−2 M and V max = 40 U/mg. Since the enzyme is active over a wide range of pH and temperature, it could find potential use in the food processing industry. PMID:24350277

High-Efficiency Nitride-Base Photonic Crystal Light Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

James Speck; Evelyn Hu; Claude Weisbuch

2010-01-31

The research activities performed in the framework of this project represent a major breakthrough in the demonstration of Photonic Crystals (PhC) as a competitive technology for LEDs with high light extraction efficiency. The goals of the project were to explore the viable approaches to manufacturability of PhC LEDS through proven standard industrial processes, establish the limits of light extraction by various concepts of PhC LEDs, and determine the possible advantages of PhC LEDs over current and forthcoming LED extraction concepts. We have developed three very different geometries for PhC light extraction in LEDs. In addition, we have demonstrated reliable methodsmore » for their in-depth analysis allowing the extraction of important parameters such as light extraction efficiency, modal extraction length, directionality, internal and external quantum efficiency. The information gained allows better understanding of the physical processes and the effect of the design parameters on the light directionality and extraction efficiency. As a result, we produced LEDs with controllable emission directionality and a state of the art extraction efficiency that goes up to 94%. Those devices are based on embedded air-gap PhC - a novel technology concept developed in the framework of this project. They rely on a simple and planar fabrication process that is very interesting for industrial implementation due to its robustness and scalability. In fact, besides the additional patterning and regrowth steps, the process is identical as that for standard industrially used p-side-up LEDs. The final devices exhibit the same good electrical characteristics and high process yield as a series of test standard LEDs obtained in comparable conditions. Finally, the technology of embedded air-gap patterns (PhC) has significant potential in other related fields such as: increasing the optical mode interaction with the active region in semiconductor lasers; increasing the coupling of the incident light into the active region of solar cells; increasing the efficiency of the phosphorous light conversion in white light LEDs etc. In addition to the technology of embedded PhC LEDs, we demonstrate a technique for improvement of the light extraction and emission directionality for existing flip-chip microcavity (thin) LEDs by introducing PhC grating into the top n-contact. Although, the performances of these devices in terms of increase of the extraction efficiency are not significantly superior compared to those obtained by other techniques like surface roughening, the use of PhC offers some significant advantages such as improved and controllable emission directionality and a process that is directly applicable to any material system. The PhC microcavity LEDs have also potential for industrial implementation as the fabrication process has only minor differences to that already used for flip-chip thin LEDs. Finally, we have demonstrated that achieving good electrical properties and high fabrication yield for these devices is straightforward.« less

Formulation and stability of an extemporaneous 0.02% chlorhexidine digluconate ophthalmic solution.

PubMed

Lin, Shu-Chiao; Huang, Chih-Fen; Shen, Li-Jiuan; Wang, Hsueh-Ju; Lin, Chia-Yu; Wu, Fe-Lin Lin

2015-12-01

Acanthamoeba keratitis is difficult to treat because Acanthamoeba cysts are resistant to the majority of antimicrobial agents. Despite the efficacy of 0.02% chlorhexidine in treating Acanthamoeba keratitis, a lack of data in the literature regarding the formulation's stability limits its clinical use. The objective of this study was to develop an optimal extemporaneous 0.02% chlorhexidine digluconate ophthalmic formulation for patients in need. With available active pharmaceutical ingredients, 0.02% chlorhexidine digluconate sample solutions were prepared by diluting with BSS Plus Solution or acetate buffer. Influences of the buffer, type of container, and temperature under daily-open condition were assessed based on the changes of pH values and chlorhexidine concentrations of the test samples weekly. To determine the beyond-use date, the optimal samples were stored at 2-8°C or room temperature, and analyzed at time 0 and at Week 1, Week 2, Week 3, Week 4, Week 5, Week 8, Week 12, and Week 24. Despite chlorhexidine exhibiting better stability in acetate buffer than in BSS solution, its shelf-life was < 14 days when stored in a light-resistant low-density polyethylene container. The acetate-buffered 0.02% chlorhexidine digluconate solution stored in light-resistant high-density polyethylene eyedroppers did not exhibit significant changes in pH or strength at any time interval. The acetate-buffered 0.02% chlorhexidine digluconate ophthalmic solution stored in light-resistant high-density polyethylene eyedroppers demonstrated excellent stability at 2-25°C for 6 months after being sealed and for 1 month after opening. This finding will enable us to prepare 0.02% chlorhexidine digluconate ophthalmic solutions based on a doctor's prescription. Copyright © 2014. Published by Elsevier B.V.

Study on oligomerization of glutamate decarboxylase from Lactobacillus brevis using asymmetrical flow field-flow fractionation (AF4) with light scattering techniques.

PubMed

Choi, Jaeyeong; Lee, Seungho; Linares-Pastén, Javier A; Nilsson, Lars

2018-01-01

In this work, asymmetrical flow field-flow fractionation (AF4) coupled with UV/Vis, multi-angle light scattering (MALS), and differential refractive index (dRI) detectors (AF4-UV-MALS-dRI) was employed for analysis of glutamate decarboxylase (LbGadB) from Lactobacillus brevis (L. brevis). AF4 provided molecular weight (MW) (or size)-based separation of dimer, hexamer, and aggregates of LbGadB. The effect of pH on oligomerization of LbGadB was investigated, and then AF4 results were compared to those from molecular modeling. The MWs measured by AF4-UV-MALS-dRI for dimeric and hexameric forms of LbGadB were 110 and 350 kDa, respectively, which are in good agreements with those theoretically calculated (110 and 330 kDa). The molecular sizes determined by AF4-UV-MALS-dRI were also in good agreement with those obtained from molecular modeling (6 and 10 nm, respectively, for dimeric and hexameric from AF4-UV-MALS-dRI and 6.4 × 7.6 and 7.6 × 13.1 nm from molecular modeling). The effects of temperature, salt type, and salt concentration on oligomerization of LbGadB were also investigated using dynamic light scattering (DLS). It was found that the hexameric form of LbGadB was most stable at pH 6 and in presence of NaCl or KCl. The results indicate that AF4, in combination of various online detectors mentioned above, provides an effective tool for monitoring of oligomerization of LbGadB under different conditions, such as temperature, pH, type of salts, and salt concentrations.

Proton gradients in intact cyanobacteria

NASA Technical Reports Server (NTRS)

Belkin, S.; Mehlhorn, R. J.; Packer, L.

1987-01-01

The internal pH values of two unicellular cyanobacterial strains were determined with electron spin resonance probes, over an external pH range of 6 to 9, in the light and in the dark. The slow growing, thylakoid-lacking Gloeobacter violaceus was found to have a low capacity for maintaining a constant internal pH. The distribution pattern of weak acid and amine nitroxide spin probes across the cell membranes of this organism, in the light and in the dark, was consistent with the assumption that it contains a single intracellular compartment. At an external pH of 7.0, intracellular pH was 6.8 in the dark and 7.2 in the light. The cells of Agmenellum quadruplicatum, a marine species, were found to contain two separate compartments; in the dark, the pH of the cytoplasmic and the intrathylakoid spaces were calculated to be 7.2 and 5.5, respectively. Upon illumination, the former increased and the latter decreased by about 0.5 pH units.

Physico-chemical factors influencing spore germination in cyanobacterium Fischerella muscicola.

PubMed

Mishra, Biranchi N; Kaushik, Manish S; Abraham, Gerard; Singh, Pawan K

2018-06-19

Spore (akinete) formation in the heterocystous and branched filamentous cyanobacterium Fischerella muscicola involves a significant increase in cell size and formation of several endospores in each of the cells. In present study, the physico-chemical factors (pH, light sources, nutrient deficiency, nitrogen sources, carbon sources, and growth hormones) affecting the germination of spores of F. muscicola were examined. Increase in spore germination frequency was detected above pH 8 with maximum germination (46.04%) recorded at pH 9, whereas a significant decrease in germination was observed at pH 6 when compared to control (pH 7.6). Spore germination was not observed at pH 5. Among light sources germination frequency followed the following order, that is, red light (39.9%) > white light (33.8%) > yellow light (3.4%) > green light (1.3%) whereas germination did not take place in dark and blue light. Ammonium chloride (NH 4 Cl) supported maximum (99.5%) germination frequency followed by calcium nitrate (Ca(NO 3 ) 2 ), potassium nitrate (KNO 3 ), and minimum germination was observed in urea. Nutrient (phosphorus, calcium, and magnesium) deficiency significantly enhanced the germination frequency with maximum increase in magnesium (Mg) deficient condition. Further, supplementation of carbon sources (glucose, fructose, and sodium acetate) and growth hormones (IAA and GA) also enhanced the germination frequency in this cyanobacterium. Therefore, it may be concluded that, those factors supporting higher germination frequency could be considered for successful production and use of this cyanobacterium in biofertilizer and other algal production technologies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Influence of pH on Prokaryotic Cell Size and Temperature

NASA Astrophysics Data System (ADS)

Sundararajan, D.; Gutierrez, F.; Heim, N. A.; Payne, J.

2015-12-01

The pH of a habitat is essential to an organism's growth and success in its environment. Although most organisms maintain a neutral internal pH, their environmental pH can vary greatly. However, little research has been done concerning an organism's environmental pH across a wide range of taxa. We studied pH tolerance in prokaryotes and its relationship with biovolume, taxonomic classification, and ideal temperature. We had three hypotheses: pH and temperature are not correlated; pH tolerance is similar within taxonomic groups; and extremophiles have small cell sizes. To test these hypotheses, we used pH, size, and taxonomic data from The Prokaryotes. We found that the mean optimum external pH was neutral for prokaryotes as a whole and when divided by domain, phylum, and class. Using ANOVA to test for pH within and among group variances, we found that variation of pH in domains, phyla, classes, and families was greater than between them. pH and size did not show much of a correlation, except that the largest and smallest sized prokaryotes had nearly neutral pH. This seems significant because extremophiles need to divert more of their energy from growth to maintain a neutral internal pH. Acidophiles showed a larger range of optimum pH values than alkaliphiles. A similar result was seen with the minimum and maximum pH values of acidophiles and alkaliphiles. While acidophiles were spread out and had some alkaline maximum values, alkaliphiles had smaller ranges, and unlike some acidophiles that had pH minimums close to zero, alkaliphile pH maximums did not go beyond a pH of 12. No statistically significant differences were found between sizes of acidophiles and alkaliphiles. However, optimum temperatures of acidophiles and alkaliphiles did have a statistically significant difference. pH and temperature had a negative correlation. Therefore, pH seems to have a correlation with cell size, temperature, and taxonomy to some extent.

Water-quality data for Smith and Bybee Lakes, Portland, Oregon, June to November, 1982

USGS Publications Warehouse

Clifton, Daphne G.

1983-01-01

Water-quality monitoring at Smith and Bybee Lakes included measurement of water temperature, dissolved oxygen concentration and percent saturation, pH, specific conductance, lake depth, alkalinity, dissolved carbon, total dissolved solids, secchi disk light transparency, nutrients, and chlorophyll a and b. In addition, phytoplankton, zooplankton, and benthic invertebrate populations were identified and enumerated. Lakebed sediment was analyzed for particle size, volatile solids, immediate oxygen demand, trace metals, total organic carbon, nutrients, and organic constituents. (USGS)

Fine-Scale Variability in Temperature, Salinity, and pH in the Upper-Ocean and the Effects on Acoustic Transmission Loss in the Western Arctic Ocean.

DTIC Science & Technology

2010-03-01

28  V.  ANALYTIC METHOD AND DATA ANALYSIS ..................................................29  A.  DATA PROCESSING ...your help getting ready for the Arctic and with the data processing back at NPS. Thank you to Professor John Colosi and LCDR Ben Jones for your help...light. Acoustic energy, however, can propagate for very long ranges (Kinsler et al. 2000). This energy can be passively received and processed , and

Proceedings, Annual Meeting, Aquatic Plant Control Research Program (17th) Held at Sacramento, California on 16-18 November 1982.

DTIC Science & Technology

1983-06-01

other pool served as the uninoculated check. The type of inoculum, water pH, water temperature, CO2 concentration in water, light intensity, and plant...crowd out the conifers . Some people decry these protests as purely emotional outbursts of an unin- formed or misinformed public. Whether this is true or...sites. Thus, the time that an effective herbicide concentration remains among sub- mersed aquatic plants after application is reduced. Adjuvants have

Titania modified activated carbon prepared from sugarcane bagasse: adsorption and photocatalytic degradation of methylene blue under visible light irradiation.

PubMed

El-Salamony, R A; Amdeha, E; Ghoneim, S A; Badawy, N A; Salem, K M; Al-Sabagh, A M

2017-12-01

Activated carbon (AC), prepared from sugarcane bagasse waste through a low-temperature chemical carbonization treatment, was used as a support for nano-TiO 2 . TiO 2 supported on AC (xTiO 2 -AC) catalysts (x = 10, 20, 50, and 70 wt.%) were prepared through a mechano-mixing method. The photocatalysts were characterized by Raman, X-ray diffraction analysis, FTIR, S BET , field emission scanning electron microscope, and optical technique. The adsorption and photo-activity of the prepared catalysts (xTiO 2 -AC) were evaluated using methylene blue (MB) dye. The photocatalytic degradation of MB was evaluated under UVC irradiation and visible light. The degradation percentage of the 100 ppm MB at neutral pH using 20TiO 2 -AC reaches 96 and 91 after 180 min under visible light and UV irradiation, respectively. In other words, these catalysts are more active under visible light than under UV light irradiation, opening the possibility of using solar light for this application.

Light induced changes of internal pH in a barnacle photoreceptor and the effect of internal pH on the receptor potential.

PubMed Central

Brown, H M; Meech, R W

1979-01-01

1. Intracellular pH (pH1) was measured in Balanus photoreceptors using pH-sensitive glass micro-electrodes. The average pH1 of twelve photoreceptors which had been dark adapted for at least 30 min was 7.3 +/- 0.07 (S.D.). 2. Illumination reduced the recorded pH1 by as much as 0.2 pH unit. The change in pH1 was graded with light intensity. 3. When the cells were exposed to CO2 in the dark, pH1 declined monophasically. Saline equilibrated with 2% CO2; 98% O2 produced a steady reduction in pH1 of about 0.25 unit in 2--3 min. The buffering capacity of the receptor cell cytoplasm calculated from such experiments is approximately 15 slykes. 4. In the presence of HCO3-1, CO2 saline produced smaller, biphasic changes in pH1. 5. The membrane depolarization produced by a bright flash (depolarizing receptor potential) was reversibly reduced in the presence of external CO2 or by injection of H+. Iontophoretic injection of HCO2- increased the amplitude of the receptor potential. 6. In individual cells there was a close correlation between the amplitude of the receptor potential and pH1. 7. Saline equilibrated with CO2 reduced the light induced current (recorded under voltage-clamp) by 40--50% without affecting its reversal potential. 8. Exposure of the receptor to 95% CO2 saline for several minutes (pH0 5.5) not only abolished the receptor potential but also reversibly decreased the K conductance of the membrane in the dark. These effects were not reproduced by pH0 5.5 buffered saline or by a 5 min exposure to saline equilibrated with N2. 9. It is suggested that changes in pH1 induced by light modulate the sensitivity of the receptor under physiological conditions. PMID:43890

Investigation of the optical response of photonic crystal nanocavities in ferroelectric oxide thin film

NASA Astrophysics Data System (ADS)

Lin, Pao Tai; Russin, William A.; Joshi-Imre, Alexandra; Ocola, Leonidas E.; Wessels, B. W.

2015-10-01

The optical properties of BaTiO3 two dimensional photonic crystal (PhC) nanocavities were investigated. Two types of nanocavities consisting of dopants and vacancies with PhC periodicities ranging from 200 to 550 nm were evaluated. The images from laser scanning confocal microscopy show the optical scattering of the PhC cavities is highly wavelength dependent. An optical intensity reversal is observed when the wavelength of probe light shifts by 29 nm. Meanwhile, intensity contrast between the nanocavity and its adjacent PhCs is enhanced as the PhC periodicity becomes shorter than the probe wavelength. To determine the photonic band structures fluorescence from dye covered PhCs were imaged and analyzed. A strong enhancement of fluorescence is observed for the PhC with a period of 200 nm. Upon comparison to the 2D finite difference time domain calculations, the enhancement is attributed to strong light localization within the PhC nanocavity. As a result, the in-plane lightwave propagation is prohibited that results in an increase in the vertical light scattering.

Optoelectronic pH Meter: Further Details

NASA Technical Reports Server (NTRS)

Jeevarajan, Antony S.; Anderson, Mejody M.; Macatangay, Ariel V.

2009-01-01

A collection of documents provides further detailed information about an optoelectronic instrument that measures the pH of an aqueous cell-culture medium to within 0.1 unit in the range from 6.5 to 7.5. The instrument at an earlier stage of development was reported in Optoelectronic Instrument Monitors pH in a Culture Medium (MSC-23107), NASA Tech Briefs, Vol. 28, No. 9 (September 2004), page 4a. To recapitulate: The instrument includes a quartz cuvette through which the medium flows as it is circulated through a bioreactor. The medium contains some phenol red, which is an organic pH-indicator dye. The cuvette sits between a light source and a photodetector. [The light source in the earlier version comprised red (625 nm) and green (558 nm) light-emitting diodes (LEDs); the light source in the present version comprises a single green- (560 nm)-or-red (623 nm) LED.] The red and green are repeatedly flashed in alternation. The responses of the photodiode to the green and red are processed electronically to obtain the ratio between the amounts of green and red light transmitted through the medium. The optical absorbance of the phenol red in the green light varies as a known function of pH. Hence, the pH of the medium can be calculated from the aforesaid ratio.

LED-CT Scan for pH Distribution on a Cross-Section of Cell Culture Medium.

PubMed

Higashino, Nobuya; Takayama, Toshio; Ito, Hiroaki; Horade, Mitsuhiro; Yamaguchi, Yasutaka; Dylan Tsai, Chia-Hung; Kaneko, Makoto

2018-01-11

In cell culture, the pH of the culture medium is one of the most important conditions. However, the culture medium may have non-uniform pH distribution due to activities of cells and changes in the environment. Although it is possible to measure the pH distribution with an existing pH meter using distributed electrodes, the method involves direct contact with the medium and would greatly increase the risk of contamination. Here in this paper, we propose a computed tomography (CT) scan for measuring pH distribution using the color change of phenol red with a light-emitting diode (LED) light source. Using the principle of CT scan, we can measure pH distribution without contacting culture medium, and thus, decrease the risk of contamination. We have developed the device with a LED, an array of photo receivers and a rotation mechanism. The system is firstly calibrated with different shapes of wooden objects that do not pass light, we succeeded in obtaining their 3D topographies. The system was also used for measuring a culture medium with two different pH values, it was possible to obtain a pH distribution that clearly shows the boundary.

Development of a Prototype Algal Reactor for Removing CO2 from Cabin Air

NASA Technical Reports Server (NTRS)

Patel, Vrajen; Monje, Oscar

2013-01-01

Controlling carbon dioxide in spacecraft cabin air may be accomplished using algal photobioreactors (PBRs). The purpose of this project was to evaluate the use of a commercial microcontroller, the Arduino Mega 2560, for measuring key photioreactor variables: dissolved oxygen, pH, temperature, light, and carbon dioxide. The Arduino platform is an opensource physical computing platform composed of a compact microcontroller board and a C++/C computer language (Arduino 1.0.5). The functionality of the Arduino platform can be expanded by the use of numerous add-ons or 'shields'. The Arduino Mega 2560 was equipped with the following shields: datalogger, BNC shield for reading pH sensor, a Mega Moto shield for controlling CO2 addition, as well as multiple sensors. The dissolved oxygen (DO) probe was calibrated using a nitrogen bubbling technique and the pH probe was calibrated via an Omega pH simulator. The PBR was constructed using a 2 L beaker, a 66 L box for addition of CO2, a micro porous membrane, a diaphragm pump, four 25 watt light bulbs, a MasterFiex speed controller, and a fan. The algae (wild type Synechocystis PCC6803) was grown in an aerated flask until the algae was dense enough to used in the main reactor. After the algae was grown, it was transferred to the 2 L beaker where CO2 consumption and O2 production was measured using the microcontroller sensor suite. The data was recorded via the datalogger and transferred to a computer for analysis.

Comprehensive model of microalgae photosynthesis rate as a function of culture conditions in photobioreactors.

PubMed

Costache, T A; Acién Fernández, F Gabriel; Morales, M M; Fernández-Sevilla, J M; Stamatin, I; Molina, E

2013-09-01

In this paper, the influence of culture conditions (irradiance, temperature, pH, and dissolved oxygen) on the photosynthesis rate of Scenedesmus almeriensis cultures is analyzed. Short-run experiments were performed to study cell response to variations in culture conditions, which take place in changing environments such as outdoor photobioreactors. Experiments were performed by subjecting diluted samples of cells to different levels of irradiance, temperature, pH, and dissolved oxygen concentration. Results demonstrate the existence of photoinhibition phenomena at irradiances higher than 1,000 μE/m(2) s; in addition to reduced photosynthesis rates at inadequate temperatures or pH-the optimal values being 35 °C and 8, respectively. Moreover, photosynthesis rate reduction at dissolved oxygen concentrations above 20 mg/l is demonstrated. Data have been used to develop an integrated model based on considering the simultaneous influence of irradiance, temperature, pH, and dissolved oxygen. The model fits the experimental results in the range of culture conditions tested, and it was validated using data obtained by the simultaneous variation of two of the modified variables. Furthermore, the model fits experimental results obtained from an outdoor culture of S. almeriensis performed in an open raceway reactor. Results demonstrate that photosynthetic efficiency is modified as a function of culture conditions, and can be used to determine the proximity of culture conditions to optimal values. Optimal conditions found (T = 35 °C, pH = 8, dissolved oxygen concentration <20 mg/l) allows to maximize the use of light by the cells. The developed model is a powerful tool for the optimal design and management of microalgae-based processes, especially outdoors, where the cultures are subject to daily culture condition variations.

Measuring pH variability using an experimental sensor on an underwater glider

NASA Astrophysics Data System (ADS)

Hemming, Michael P.; Kaiser, Jan; Heywood, Karen J.; Bakker, Dorothee C. E.; Boutin, Jacqueline; Shitashima, Kiminori; Lee, Gareth; Legge, Oliver; Onken, Reiner

2017-05-01

Autonomous underwater gliders offer the capability of measuring oceanic parameters continuously at high resolution in both vertical and horizontal planes, with timescales that can extend to many months. An experimental ion-sensitive field-effect transistor (ISFET) sensor measuring pH on the total scale was attached to a glider during the REP14-MED experiment in June 2014 in the Sardinian Sea in the northwestern Mediterranean. During the deployment, pH was sampled at depths of up to 1000 m along an 80 km transect over a period of 12 days. Water samples were collected from a nearby ship and analysed for dissolved inorganic carbon concentration and total alkalinity to derive the pH for validating the ISFET sensor measurements. The vertical resolution of the pH sensor was good (1 to 2 m), but stability was poor and the sensor drifted in a non-monotonous fashion. In order to remove the sensor drift, a depth-constant time-varying offset was applied throughout the water column for each dive, reducing the spread of the data by approximately two-thirds. Furthermore, the ISFET sensor required temperature- and pressure-based corrections, which were achieved using linear regression. Correcting for this decreased the apparent sensor pH variability by a further 13 to 31 %. Sunlight caused an apparent sensor pH decrease of up to 0.1 in surface waters around local noon, highlighting the importance of shielding the sensor from light in future deployments. The corrected pH from the ISFET sensor is presented along with potential temperature, salinity, potential density anomalies (σθ), and dissolved oxygen concentrations (c(O2)) measured by the glider, providing insights into the physical and biogeochemical variability in the Sardinian Sea. The pH maxima were identified close to the depth of the summer chlorophyll maximum, where high c(O2) values were also found. Longitudinal pH variations at depth (σθ > 28. 8 kg m-3) highlighted the variability of water masses in the Sardinian Sea. Higher pH was observed where salinity was > 38. 65, and lower pH was found where salinity ranged between 38.3 and 38.65. The higher pH was associated with saltier Levantine Intermediate Water, and it is possible that the lower pH was related to the remineralisation of organic matter. Furthermore, shoaling isopycnals closer to shore coinciding with low pH and c(O2), high salinity, alkalinity, dissolved inorganic carbon concentrations, and chlorophyll fluorescence waters may be indicative of upwelling.

Tuning of thermally induced sol-to-gel transitions of moderately concentrated aqueous solutions of doubly thermosensitive hydrophilic diblock copolymers poly(methoxytri(ethylene glycol) acrylate)-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid).

PubMed

Jin, Naixiong; Zhang, Hao; Jin, Shi; Dadmun, Mark D; Zhao, Bin

2012-03-15

We report in this article a method to tune the sol-to-gel transitions of moderately concentrated aqueous solutions of doubly thermosensitive hydrophilic diblock copolymers that consist of two blocks exhibiting distinct lower critical solution temperatures (LCSTs) in water. A small amount of weak acid groups is statistically incorporated into the lower LCST block so that its LCST can be tuned by varying solution pH. Well-defined diblock copolymers, poly(methoxytri(ethylene glycol) acrylate)-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid) (PTEGMA-b-P(DEGEA-co-AA)), were prepared by reversible addition-fragmentation chain transfer polymerization and postpolymerization modification. PTEGMA and PDEGEA are thermosensitive water-soluble polymers with LCSTs of 58 and 9 °C, respectively, in water. A 25 wt % aqueous solution of PTEGMA-b-P(DEGEA-co-AA) with a molar ratio of DEGEA to AA units of 100:5.2 at pH = 3.24 underwent multiple phase transitions upon heating, from a clear, free-flowing liquid (<15 °C) to a clear, free-standing gel (15-46 °C) to a clear, free-flowing hot liquid (47-56 °C), and a cloudy mixture (≥57 °C). With the increase of pH, the sol-to-gel transition temperature (T(sol-gel)) shifted to higher values, while the gel-to-sol transition (T(gel-sol)) and the clouding temperature (T(clouding)) of the sample remained essentially the same. These transitions and the tunability of T(sol-gel) originated from the thermosensitive properties of two blocks of the diblock copolymer and the pH dependence of the LCST of P(DEGEA-co-AA), which were confirmed by dynamic light scattering and differential scanning calorimetry studies. Using the vial inversion test method, we mapped out the C-shaped sol-gel phase diagrams of the diblock copolymer in aqueous buffers in the moderate concentration range at three different pH values (3.24, 5.58, and 5.82, all measured at ~0 °C). While the upper temperature boundaries overlapped, the lower temperature boundary shifted upward and the critical gelation concentration increased with the increase of pH. The AA content in PTEGMA-b-P(DEGEA-co-AA) was found to have a significant effect on the pH dependence of T(sol-gel). For PTEGMA-b-P(DEGEA-co-AA) with a molar ratio of DEGEA to AA units of 100:10, the T(sol-gel) of its 25 wt % aqueous solution increased faster with the increase of pH than that of PTEGMA-b-P(DEGEA-co-AA) with a DEGEA-to-AA molar ratio of 100:5.2. © 2012 American Chemical Society

The initial freezing point temperature of beef rises with the rise in pH: a short communication.

PubMed

Farouk, M M; Kemp, R M; Cartwright, S; North, M

2013-05-01

This study tested the hypothesis that the initial freezing point temperature of meat is affected by pH. Sixty four bovine M. longissimus thoracis et lumborum were classified into two ultimate pH groups: low (<5.8) and high pH (>6.2) and their cooling and freezing point temperatures were determined. The initial freezing temperatures for beef ranged from -0.9 to -1.5°C (∆=0.6°C) with the higher and lower temperatures associated with high and low ultimate pH respectively. There was a significant correlation (r=+0.73, P<0.01) between beef pH and freezing point temperature in the present study. The outcome of this study has implications for the meat industry where evidence of freezing (ice formation) in a shipment as a result of high pH meat could result in a container load of valuable chilled product being downgraded to a lower value frozen product. Copyright © 2013 Elsevier Ltd. All rights reserved.

Light-induced spatial control of pH-jump reaction at smart gel interface.

PubMed

Techawanitchai, Prapatsorn; Ebara, Mitsuhiro; Idota, Naokazu; Aoyagi, Takao

2012-11-01

We proposed here a 'smart' control of an interface movement of proton diffusion in temperature- and pH-responsive hydrogels using a light-induced spatial pH-jump reaction. A photoinitiated proton-releasing reaction of o-nitrobenzaldehyde (NBA) was integrated into poly(N-isopropylacrylamide-o-2-carboxyisopropylacrylamide) (P(NIPAAm-co-CIPAAm)) hydrogels. NBA-integrated hydrogels demonstrated quick release of proton upon UV irradiation, allowing the pH inside the gel to decrease below the pK(a) of P(NIPAAm-co-CIPAAm) within a minute. The NBA-integrated gel was shown to shrink rapidly upon UV irradiation without polymer "skin layer" formation due to a uniform decrease of pH inside the gel. Spatial control of gel shrinking was also created by irradiating UV light to a limited region of the gel through a photomask. The interface of proton diffusion ("active interface") gradually moved toward non-illuminated area. The apparent position of "active interface", however, did not change remarkably above the LCST, while protons continuously diffused outward direction. This is because the "active interface" also moved inward direction as gel shrank above the LCST. As a result, slow movement of the apparent interface was observed. The NBA-integrated gel was also successfully employed for the controlled release of an entrapped dextran in a light controlled manner. This system is highly promising as smart platforms for triggered and programmed transportation of drugs. Copyright © 2011 Elsevier B.V. All rights reserved.

Integrated pressure and temperature sensor with high immunity against external disturbance for flexible endoscope operation

NASA Astrophysics Data System (ADS)

Maeda, Yusaku; Maeda, Kohei; Kobara, Hideki; Mori, Hirohito; Takao, Hidekuni

2017-04-01

In this study, an integrated pressure and temperature sensor device for a flexible endoscope with long-term stability in in vivo environments was developed and demonstrated. The sensor, which is embedded in the thin wall of the disposable endoscope hood, is intended for use in endoscopic surgery. The device surface is coated with a Cr layer to prevent photoelectronic generation induced by the strong light of the endoscope. The integrated temperature sensor allows compensation for the effect of the temperature drift on a pressure signal. The fabricated device pressure resolution is 0.4 mmHg; the corresponding pressure error is 3.2 mmHg. The packaged device was used in a surgical simulation in an animal experiment. Pressure and temperature monitoring was achieved even in a pH 1 acid solution. The device enables intraluminal pressure and temperature measurements of the stomach, which facilitate the maintenance of internal stomach conditions. The applicability of the sensor was successfully demonstrated in animal experiments.

Stabilized micelles of amphoteric polyurethane formed by thermoresponsive micellization in HCl aqueous solution.

PubMed

Qiao, Yong; Zhang, Shifeng; Lin, Ouya; Deng, Liandong; Dong, Anjie

2008-04-01

The thermoresponsive micellization behavior of amphoteric polyurethane (APU) was studied in HCl aqueous solution (pH 2.0) through light scattering, transmission electron microscopy, and fluorescent measurement. When APU concentration is high enough, nonreversible assembly of macromolecules can be observed with temperature decreasing from 25 to 4 degrees C. However, micelles reaching equilibrium at 4 degrees C can self-assemble reversibly in the temperature range of 4-55 degrees C. According to our research, we found it is the temperature sensitivity of the poly(propylene oxide) (PPO) segments that leads to the reassembly of APU at lower temperature. We proposed that core-shell-corona micelles ultimately form with hydrophobic core, PPO shell, and hydrophilic corona when temperature increases from 4 to 25 degrees C. This structure is very stable and does not change at higher temperatures (25-55 degrees C). That provides a new way to obtain stable micelles with small size and narrow size distribution at higher concentration of APU.

Compensation of ocean acidification effects in Arctic phytoplankton assemblages

NASA Astrophysics Data System (ADS)

Hoppe, Clara Jule Marie; Wolf, Klara K. E.; Schuback, Nina; Tortell, Philippe D.; Rost, Björn

2018-06-01

The Arctic and subarctic shelf seas, which sustain large fisheries and contribute to global biogeochemical cycling, are particularly sensitive to ongoing ocean acidification (that is, decreasing seawater pH due to anthropogenic CO2 emissions). Yet, little information is available on the effects of ocean acidification on natural phytoplankton assemblages, which are the main primary producers in high-latitude waters. Here we show that coastal Arctic and subarctic primary production is largely insensitive to ocean acidification over a large range of light and temperature levels in different experimental designs. Out of ten CO2-manipulation treatments, significant ocean acidification effects on primary productivity were observed only once (at temperatures below 2 °C), and shifts in the species composition occurred only three times (without correlation to specific experimental conditions). These results imply a high capacity to compensate for environmental variability, which can be understood in light of the environmental history, tolerance ranges and intraspecific diversity of the dominant phytoplankton species.

Direct 1H NMR evidence of spin-rotation coupling as a source of para → ortho-H2 conversion in diamagnetic solvents.

PubMed

Terenzi, Camilla; Bouguet-Bonnet, Sabine; Canet, Daniel

2017-04-21

At ambient temperature, conversion from 100% enriched para-hydrogen (p-H 2 ; singlet state) to ortho-hydrogen (o-H 2 ; triplet state) leads necessarily to the thermodynamic equilibrium proportions: 75% of o-H 2 and 25% of p-H 2 . When p-H 2 is dissolved in a diamagnetic organic solvent, conversion is very slow and can be considered as arising from nuclear spin relaxation phenomena. A first relaxation mechanism, specific to the singlet state and involving a combination of auto-correlation and cross correlation spectral densities, can be retained: randomly fluctuating magnetic fields due to inter-molecular dipolar interactions. We demonstrate here that (i) this dipolar mechanism is not sufficient for accounting for the para→ortho conversion rate, (ii) spin-rotation interaction, an intra-molecular mechanism, behaves similarly to random-field interaction and, thus, may be involved in the singlet relaxation rate. Also, as the para→ortho conversion is monitored by proton nuclear magnetic resonance (NMR) of dissolved o-H 2 (p-H 2 is NMR-silent), one has to account for H 2 exchange between the liquid phase and the gas phase within the NMR tube, as well as for dissolution effects. Experimental evidence of the above statements is brought here in the case of two organic solvents: acetone-d 6 and carbon disulfide. The observed temperature dependence of the para→ortho conversion rate shows that spin-rotation can be the dominant contribution to the p-H 2 relaxation rate in the absence of tangible dipolar interactions. Our findings shed new light on the "mysterious" mechanism of the para→ortho conversion which has been searched for several decades.

Modelling lamb carcase pH and temperature decline parameters: relationship to shear force and abattoir variation.

PubMed

Hopkins, David L; Holman, Benjamin W B; van de Ven, Remy J

2015-02-01

Carcase pH and temperature decline rates influence lamb tenderness; therefore pH decline parameters are beneficial when modelling tenderness. These include pH at temperature 18 °C (pH@Temp18), temperature when pH is 6 (Temp@pH6), and pH at 24 h post-mortem (pH24). This study aimed to establish a relationship between shear force (SF) as a proxy for tenderness and carcase pH decline parameters estimated using both linear and spline estimation models for the m. longissimus lumborum (LL). The study also compared abattoirs regarding their achievement of ideal pH decline, indicative of optimal tenderness. Based on SF measurements of LL and m. semimembranosus collected as part of the Information Nucleus slaughter programme (CRC for Sheep Industry Innovation) this study found significant relationships between tenderness and pH24LL, consistent across the meat cuts and ageing periods examined. Achievement of ideal pH decline was shown not to have significantly differed across abattoirs, although rates of pH decline varied significantly across years within abattoirs.

Absorption and emission spectroscopic characterization of BLUF protein Slr1694 from Synechocystis sp. PCC6803 with roseoflavin cofactor.

PubMed

Zirak, P; Penzkofer, A; Mathes, T; Hegemann, P

2009-11-09

The wild-type BLUF protein Slr1694 from Synechocystis sp. PCC6803 (BLUF=blue-light sensor using FAD) has flavin adenosine dinucleotide (FAD) as natural cofactor. This light sensor causes positive phototaxis of the marine cyanobacterium. In this study the FAD cofactor of the wild-type Slr1694 was replaced by roseoflavin (RoF) and the roseoflavin derivatives RoFMN and RoFAD during heterologous expression in a riboflavin auxotrophic E. coli strain. An absorption and emission spectroscopic characterization of the cofactor-exchanged-Slr1694 (RoSlr) was carried out both under dark conditions and under illuminated conditions. The behaviour of RoF embedded in RoSlr in aqueous solution at pH 8 is compared with the behaviour of RoF in aqueous solution. The fluorescence of RoF and RoSlr is quenched by photo-induced twisted intra-molecular charge transfer at room temperature with stronger effect for RoF. The fluorescence quenching is diminished at liquid nitrogen temperature. Light exposure of RoSlr causes irreversible conversion of the protein embedded roseoflavins to 8-methylamino-flavins, 8-dimethylamino-lumichrome and 8-methylamino-lumichrome.

Climate-simulated raceway pond culturing: quantifying the maximum achievable annual biomass productivity of Chlorella sorokiniana in the contiguous USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huesemann, M.; Chavis, A.; Edmundson, S.

Chlorella sorokiniana (DOE 1412) emerged as one of the most promising microalgae strains from the NAABB consortium project, with a remarkable doubling time under optimal conditions of 2.57 hr-1. However, its maximum achievable annual biomass productivity in outdoor ponds in the contiguous United States remained unknown. In order to address this knowledge gap, this alga was cultured in indoor LED-lighted and temperature-controlled raceways in nutrient replete freshwater (BG-11) medium at pH 7 under conditions simulating the daily sunlight intensity and water temperature fluctuations during three seasons in Southern Florida, an optimal outdoor pond culture location for this organism identified bymore » biomass growth modeling. Prior strain characterization indicated that the average maximum specific growth rate (µmax) at 36 ºC declined continuously with pH, with µmax corresponding to 5.92, 5.83, 4.89, and 4.21 day-1 at pH 6, 7, 8, and 9, respectively. In addition, the maximum specific growth rate declined nearly linearly with increasing salinity until no growth was observed above 35 g/L NaCl. In the climate-simulated culturing studies, the volumetric ash-free dry weight-based biomass productivities during the linear growth phase were 57, 69, and 97 mg/L-day for 30-year average light and temperature simulations for January (winter), March (spring), and July (summer), respectively, which corresponds to average areal productivities of 11.6, 14.1, and 19.9 g/m2-day at a constant pond depth of 20.5 cm. The photosynthetic efficiencies (PAR) in the three climate-simulated pond culturing experiments ranged from 4.1 to 5.1%. The annual biomass productivity was estimated as ca. 15 g/m2-day, nearly double the U.S. Department of Energy (DOE) 2015 State of Technology annual cultivation productivity of 8.5 g/m2-day, but this is still significantly below the projected 2022 target of ca. 25 g/m2-day (U.S. DOE, 2016) for economic microalgal biofuel production, indicating the need for additional research in strain biology and system engineering.« less

AND logic-like pH- and light-dual controlled drug delivery by surface modified mesoporous silica nanoparticles.

PubMed

Zhao, Junwei; He, Zhaoshuai; Li, Biao; Cheng, Tanyu; Liu, Guohua

2017-04-01

Recently, the controlled drug delivery system has become a potential platform for biomedical application. Herein, we developed a pH and light-dual controlled cargo release system exhibiting AND logic based on MCM-41 mesoporous silica nanoparticles, which was surface modified using β-cyclodextrin (β-CD) with imine bond and azobenzene derivative. The complex of β-CD and azobenzene derivative effectively blocked the cargo delivery in pH=7.0 phosphate buffered saline (PBS) solution without 365nm UV light irradiation. The cargo was fully released when both factors of acidic environment (pH=5.0 PBS) and 365nm UV light irradiation were satisfied, meanwhile only very little cargo was delivered if one factor was satisfied. The result also demonstrates that the opening/closing of the gate and the release of the cargo in small portions can be controlled. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Temperature on Bacterial Communities and Metabolites during Fermentation of Myeolchi-Aekjeot, a Traditional Korean Fermented Anchovy Sauce.

PubMed

Jung, Ji Young; Lee, Hyo Jung; Chun, Byung Hee; Jeon, Che Ok

2016-01-01

Myeolchi-aekjeot (MA) in Korea is produced outdoors without temperature controls, which is a major obstacle to produce commercial MA products with uniform quality. To investigate the effects of temperature on MA fermentation, pH, bacterial abundance and community, and metabolites were monitored during fermentation at 15°C, 20°C, 25°C, and 30°C. Initial pH values were approximately 6.0, and pH values increased after approximately 42 days, with faster increases at higher temperatures. Bacterial abundances increased rapidly in all MA samples after quick initial decreases during early fermentation and then they again steadily decreased after reaching their maxima, which were significantly greater at higher temperatures. Bacterial community analysis revealed that Proteobacteria and Tenericutes were predominant in all initial MA samples, but they were rapidly displaced by Firmicutes as fermentation progressed. Photobacterium and Mycoplasma belonging to Proteobacteria and Tenericutes, respectively, which may include potentially pathogenic strains, were dominant in initial MA, but decreased with the growth of Chromohalobacter, which occurred faster at higher temperatures--they were dominant until 273 and 100 days at 15°C and 20°C, respectively, but not detected after 30 days at 25°C and 30°C. Chromohalobacter also decreased with the appearance of subsequent genera belonging to Firmicutes in all MA samples. Tetragenococcus, halophilic lactic acid bacteria, appeared predominantly at 20°C, 25°C, and 30°C; they were most abundant at 30°C, but not detected at 15°C. Alkalibacillus and Lentibacillus appeared as dominant genera with the decrease of Tetragenococcus at 25°C and 30°C, but only Lentibacillus was dominant at 15°C and 20°C. Metabolite analysis showed that amino acids related to tastes were major metabolites and their concentrations were relatively higher at high temperatures. This study suggests that high temperatures (approximately 30°C) may be appropriate in MA fermentation, in the light of faster disappearance of potentially pathogenic genera, higher amino acids, growth of Tetragenococcus, and faster fermentation.

THE NATURE AND CONTROL OF REACTIONS IN BIOLUMINESCENCE

PubMed Central

Johnson, F. H.; Eyring, H.; Steblay, R.; Chaplin, H.; Huber, C.; Gherardi, G.

1945-01-01

On the basis of available data with regard to the chemical and physical properties of the "substrate" luciferin (LH2) and enzyme, luciferase (A), and of kinetic data derived both from the reaction in extracts of Cypridina, and from the luminescence of intact bacteria, the fundamental reactions involved in the phenomenon of bioluminescence have been schematized. These reactions provide a satisfactory basis for interpreting the known characteristics of the system, as well as the theoretical chemistry with regard to the control of its over-all velocity in relation to various factors. These factors, here studied experimentally wholly with bacteria, Photobacterium phosphoreum in particular, include pH, temperature, pressure, and the drugs sulfanilamide, urethane, and alcohol, separately and in relation to each other. Under steady state conditions of bacterial luminescence, with excess of oxidizable substrate and with oxygen not limiting, the data indicate that the chief effects of these agents center around the pace setting reactions, which may be designated by the equation: A + LH2 → ALH2 following which light emission is assumed proportional to the amount of the excited molecule, AL*. The relation between pH and luminescence intensity varies with (a), the buffer mixture and concentration, (b), the temperature, and (c), the hydrostatic pressure. At an optimum temperature for luminescence of about 22° C. in P. phosphoreum, the effects of increasing or decreasing the hydrogen ion concentration are largely reversible over the range between pH 3.6 and pH 8.8. The relation between luminescence intensity and pH, under the experimental conditions employed, is given by the following equation, in which I 1 represents the maximum intensity, occurring about pH 6.5; I 2 the intensity at any other given pH; K 5 the equilibrium constant between hydrogen ions and the AL-; and K 6 the corresponding constant with respect to hydroxyl ions: See PDF for Equation The value of K 5, as indicated by the data, amounts to 4.84 x 104, while that of K 6 amounts to 4.8 x 105. Beyond the range between approximately pH 3.8 and 8.8, destructive effects of the hydrogen and hydroxyl ions, respectively, were increasingly apparent. By raising the temperature above the optimum, the destructive effects were apparent at all pH, and the intensity of the luminescence diminished logarithmically with time. With respect to pH, the rate of destruction of the light-emitting system at temperatures above the optimum was slowest between pH 6.5 and 7.0, and increased rapidly with more acid or more alkaline reactions of the medium. The reversible effects of slightly acid pH vary with the temperature in the manner of an inhibitor (Type I) that acts independently of the normal, reversible denaturation equilibrium (K 1) of the enzyme. The per cent inhibition caused by a given acid pH in relation to the luminescence intensity at optimum pH, is much greater at low temperatures, and decreases as the temperature is raised towards the optimum temperature. The observed maximum intensity of luminescence is thus shifted to slightly higher temperatures by increase in (H+). The apparent activation energy of luminescence is increased by a decrease in pH. The value of ΔH‡ at pH 5.05 was calculated to be 40,900 calories, in comparison with 20,700 at a pH of 6.92. The difference of 20,200 is taken to represent an estimate of the heat of ionization of ALH in the activation process, and compares roughtly with the 14,000 calories estimated for the same process, by analyzing the data from the point of view of hydrogen ions as an inhibitor. The decreasing temperature coefficient for luminescence in proceeding from low temperatures towards the optimum is accounted for in part by the greater degree of ionization of ALH. At the optimum temperature and acid reactions, pressures up to about 500 atmospheres retard the velocity of the luminescent oxidation. At the same temperature, with decrease in hydrogen ion concentration, the pressure effect is much less, indicating a considerable volume increase in the process of ionization and activation. In the extremely alkaline range, beyond pH 9, luminescence is greatly reduced, as compared with the intensity at neutrality, and under these conditions pressure causes a pronounced increase in intensity, presumably by acting upon the reversible denaturation equilibrium of the protein enzyme, A. Sulfanilamide, in neutral solutions, acts on luminescence in a manner very much resembling that of hydrogen ions at acidities between pH 4.0 and pH 6.5. Like the hydrogen ion equilibrium, the sulfanilamide equilibrium involves a ratio of approximately one inhibitor molecule to one enzyme molecule. The heat of reaction amounts to about 11,600 calories or more in a reversible combination that evidently evolves heat. Like the action of H ions, sulfanilamide causes a slight shifting of maximum luminescence intensity in the direction of higher temperatures, and an increase in the energy of activation. The effect of sulfanilamide on the growth of broth cultures of eight species of luminous bacteria indicates that there is no regular relationship among the different organisms between the concentration of the drug that prevents growth, and that which prevents luminescence in the cells which develop in the presence of sulfanilamide. p-Aminobenzoic acid (PAB) antagonizes the sulfanilamide inhibition of growth in luminous bacteria, and the cultures that develop are luminous. When (PAB) is added to cells from fully developed cultures, it has no effect on luminescence, or causes a slight inhibition, depending on the concentration. With luminescence partly inhibited by sulfanilamide, the addition of PAB has no effect, or has an inhibitory effect which adds to that caused by sulfanilamide. Two different, though possibly related, enzyme systems thus appear to limit growth and luminescence, respectively. The possible mechanism through which both the inhibitions and the antagonism take place is discussed. The irreversible destruction of the luminescent system at temperatures above that of the maximum luminescence, in a medium of favorable pH to which no inhibitors have been added, proceeds logarithmically with time at both normal and increased hydrostatic pressures. Pressure retards the rate of the destruction, and the analysis of the data indicates that a volume increase of roughly 71 cc. per gm. molecule at 32° C. takes place in going from the normal to the activated state in this reaction. At normal pressure, the rate of destruction has a temperature coefficient of approximately 90,000 calories, or about 20,000 calories more than the heat of reaction in the reversible denaturation equilibrium. The data indicate that the equilibrium and the rate process are two distinct reactions. The equation for luminescence intensity, taking into account both the reversible and irreversible phases of the reaction is given below. In the equation b is a proportionality constant; k' the rate constant of the luminescent reaction; A0 the total luciferase; A0i the total initial luciferase at time t equals 0; kn the rate constant for the destruction of the native, active form of the enzyme; kd the rate constant for the destruction of the reversibly denatured, inactive form; t the time; and the other symbols are as indicated above: See PDF for Equation For reasons cited in the text, kn evidently equals kd. Urethane and alcohol, respectively, act in a manner (Type II) that promotes the breaking of the type of bonds broken in both the reversible and irreversible reactions and so promotes the irreversible denaturation. This result is in contrast to the effects of sulfanilamide, which at appropriate concentrations may give rise to the same initial inhibition as that caused by urethane, but remains constant with time. The inhibition caused by urethane and alcohol, respectively, increases as the temperature is raised. As a result, the apparent optimum is shifted to lower temperatures, and the activation energy for the over-all process of luminescence diminishes. An analysis for the approximate heat of reaction in the equilibrium between these drugs and the enzyme, indicates 65,000 calories for urethane, and 37,000 for alcohol. A similar analysis with respect to the effect of hydroxyl ions as the inhibitor gives 60,300 calories. The effects of alcohol and urethane are sensitive to hydrostatic pressure. Moderate inhibitions at optimum temperature and pH, caused by relatively small concentrations of either drug, are completely abolished by pressures of 3,000 to 4,000 pounds per square inch. At optimum temperature and pH, increasing concentrations of alcohol caused the apparent optimum pressure for luminescence to shift markedly in the direction of higher pressures. Analysis of the data with respect to concentration of alcohol at different pressures indicated that the ratio of alcohol to enzyme molecules amounted to approximately 4, at 7,000 pounds, but only about 2.8 at normal pressures. This phenomenon was taken to indicate that more than one equilibrium is established between the alcohol and the protein. A similar interpretation was suggested in connection with the fact that analysis of the relation between concentration of urethane and amount of inhibition at different temperatures also indicated a ratio of urethane to enzyme molecules that increased with temperature in the equilibria involved. Analysis of the data with respect to pressure and the inhibition caused by a given concentration of alcohol at different temperatures indicated that the volume change involved in the combination of alcohol with the enzyme must be very small, while the actual effect of pressure is apparently mediated through the reversible denaturation of the protein enzyme, which is promoted by alcohol, urethane, and drugs of similar type. PMID:19873433

The Effects of Physicochemical Factors and Cell Density on Nitrite Transformation in a Lipid-Rich Chlorella.

PubMed

Liang, Fang; Du, Kui; Wen, Xiaobin; Luo, Liming; Geng, Yahong; Li, Yeguang

2015-12-28

To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO3 concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m(2); temperature: 30°C; pH: 7-8; NaHCO3 concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R(2) = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NOX.

A gold nanocluster-based fluorescent probe for simultaneous pH and temperature sensing and its application to cellular imaging and logic gates

NASA Astrophysics Data System (ADS)

Wu, Yun-Tse; Shanmugam, Chandirasekar; Tseng, Wei-Bin; Hiseh, Ming-Mu; Tseng, Wei-Lung

2016-05-01

Metal nanocluster-based nanomaterials for the simultaneous determination of temperature and pH variations in micro-environments are still a challenge. In this study, we develop a dual-emission fluorescent probe consisting of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and fluorescein-5-isothiocyanate (FITC) as temperature- and pH-responsive fluorescence signals. Under single wavelength excitation the FITC/BSA-AuNCs exhibited well-separated dual emission bands at 525 and 670 nm. When FITC was used as a reference fluorophore, FITC/BSA-AuNCs showed a good linear response over the temperature range 1-71 °C and offered temperature-independent spectral shifts, temperature accuracy, activation energy, and reusability. The possible mechanism for high temperature-induced fluorescence quenching of FITC/BSA-AuNCs could be attributed to a weakening of the Au-S bond, thereby lowering the charge transfer from BSA to AuNCs. Additionally, the pH- and temperature-responsive properties of FITC/BSA-AuNCs allow simultaneous temperature sensing from 21 to 41 °C (at intervals of 5 °C) and pH from 6.0 to 8.0 (at intervals of 0.5 pH unit), facilitating the construction of two-input AND logic gates. Three-input AND logic gates were also designed using temperature, pH, and trypsin as inputs. The practicality of using FITC/BSA-AuNCs to determine the temperature and pH changes in HeLa cells is also validated.Metal nanocluster-based nanomaterials for the simultaneous determination of temperature and pH variations in micro-environments are still a challenge. In this study, we develop a dual-emission fluorescent probe consisting of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and fluorescein-5-isothiocyanate (FITC) as temperature- and pH-responsive fluorescence signals. Under single wavelength excitation the FITC/BSA-AuNCs exhibited well-separated dual emission bands at 525 and 670 nm. When FITC was used as a reference fluorophore, FITC/BSA-AuNCs showed a good linear response over the temperature range 1-71 °C and offered temperature-independent spectral shifts, temperature accuracy, activation energy, and reusability. The possible mechanism for high temperature-induced fluorescence quenching of FITC/BSA-AuNCs could be attributed to a weakening of the Au-S bond, thereby lowering the charge transfer from BSA to AuNCs. Additionally, the pH- and temperature-responsive properties of FITC/BSA-AuNCs allow simultaneous temperature sensing from 21 to 41 °C (at intervals of 5 °C) and pH from 6.0 to 8.0 (at intervals of 0.5 pH unit), facilitating the construction of two-input AND logic gates. Three-input AND logic gates were also designed using temperature, pH, and trypsin as inputs. The practicality of using FITC/BSA-AuNCs to determine the temperature and pH changes in HeLa cells is also validated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02341j

Laboratory study on coprecipitation of phosphate with ikaite in sea ice

NASA Astrophysics Data System (ADS)

Hu, Yu-Bin; Dieckmann, Gerhard S.; Wolf-Gladrow, Dieter A.; Nehrke, Gernot

2014-10-01

Ikaite (CaCO3·6H2O) has recently been discovered in sea ice, providing first direct evidence of CaCO3 precipitation in sea ice. However, the impact of ikaite precipitation on phosphate (PO4) concentration has not been considered so far. Experiments were set up at pH from 8.5 to 10.0, salinities from 0 to 105, temperatures from -4°C to 0°C, and PO4 concentrations from 5 to 50 µmol kg-1 in artificial sea ice brine so as to understand how ikaite precipitation affects the PO4 concentration in sea ice under different conditions. Our results show that PO4 is coprecipitated with ikaite under all experimental conditions. The amount of PO4 removed by ikaite precipitation increases with increasing pH. Changes in salinity (S ≥ 35) as well as temperature have little impact on PO4 removal by ikaite precipitation. The initial PO4 concentration affects the PO4 coprecipitation. These findings may shed some light on the observed variability of PO4 concentration in sea ice.

Crystal structures of different substrates of bacteriorhodopsin's M intermediate at various pH levels.

PubMed

Yamamoto, Masataka; Hayakawa, Naoki; Murakami, Midori; Kouyama, Tsutomu

2009-10-30

The hexagonal P622 crystal of bacteriorhodopsin, which is made up of stacked membranes, is stable provided that the precipitant concentration in the soaking solution is higher than a critical value (i.e., 1.5 M ammonium sulfate). Diffraction data showed that the crystal lattice shrank linearly with increasing precipitant concentration, due primarily to narrowing of intermembrane spaces. Although the crystal shrinkage did not affect the rate of formation of the photoreaction M intermediate, its lifetime increased exponentially with the precipitant concentration. It was suggested that the energetic barrier of the M-to-N transition becomes higher when the motional freedom of the EF loop is reduced by crystal lattice force. As a result of this property, the M state accumulated predominantly when the crystal that was soaked at a high precipitant concentration was illuminated at room temperature. Structural data obtained at various pH levels showed that the overall structure of M is not strongly dependent on pH, except that Glu194 and Glu204 in the proton release complex are more separated at pH 7 than at pH 4.4. This result suggests that light-induced disruption of the paired structure of Glu194 and Glu204 is incomplete when external pH is lower than the pK(a) value of the proton release group in the M state.

Effect of soft drinks on proximal plaque pH at normal and low salivary secretion rates.

PubMed

Johansson, Ann-Katrin; Lingström, Peter; Birkhed, Dowen

2007-11-01

The aim of this study was to investigate the effect of different types of drinks on plaque pH during normal and drug-induced low salivary secretion rates. Three drinks were tested in 10 healthy adult subjects: 1) Coca-Cola regular, 2) Coca-Cola light, and 3) fresh orange juice. pH was measured in the maxillary incisor and premolar region with the microtouch method. The area under the pH curve (AUC) was calculated. During normal salivary condition, mouth-rinsing with Coca-Cola regular resulted in a slightly more pronounced drop in pH during the first few minutes than it did with orange juice. After this initial phase, both products showed similar and relatively slow pH recovery. Coca-Cola light also resulted in low pH values during the very first minutes, but thereafter in a rapid recovery back to baseline. During dry mouth conditions, the regular Cola drink showed a large initial drop in pH, and slightly more pronounced than for orange juice. After the initial phase, both products had a similar and slow recovery back to baseline. At most time-points, AUC was significantly greater in dry conditions compared to normal conditions for Coca-Cola regular and orange juice, but not for Coca-Cola light. Coca-Cola light generally showed a significantly smaller AUC than Coca-Cola regular and orange juice. The main conclusion from this study is that a low salivary secretion rate may accentuate the fall in pH in dental plaque after gentle mouth-rinsing with soft drinks.

Stability of tranexamic acid in 0.9% sodium chloride, stored in type 1 glass vials and ethylene/propylene copolymer plastic containers.

PubMed

McCluskey, Susan V; Sztajnkrycer, Matthew D; Jenkins, Donald A; Zietlow, Scott P; Berns, Kathleen S; Park, Myung S

2014-01-01

Tranexamic acid has recently been demonstrated to decrease all-cause mortality and deaths due to hemorrhage in trauma patients. The optimal administration of tranexamic acid is within one hour of injury, but not more than three hours from the time of injury. To aid with timely administration, a premixed solution of 1 gram tranexamic acid and 0.9% sodium chloride was proposed to be stocked as a medication in both the aeromedical transport helicopters and Emergency Department at Mayo Clinic Hospital--Rochester Saint Marys Campus. Since no published stability data exists for tranexamic acid diluted with 0.9% sodium chloride, this study was undertaken to determine the stability of tranexamic acid diluted with 0.9% sodium chloride while being stored in two types of containers. Stability was determined through the use of a stability-indicating high-performance liquid reverse phase chromatography assay, pH, and visual tests. Tranexamic acid solutions of 1 gram in 0.9% sodium chloride 65 mL were studied at predetermined intervals for 90 days in ethylene/propylene copolymer plastic containers, protected from light, and at both controlled room and refrigerated temperatures. Tranexamic acid solutions of 1 gram in 0.9% sodium chloride 50 mL were studied at predetermined intervals for 180 days in clear Type 1 borosilicate glass vials sealed with intact elastomeric, Flourotec-coated stoppers, stored protected from light at controlled room temperature. Solutions stored in the ethylene/propylene copolymer plastic containers at both storage temperatures maintained at least 98% of initial potency throughout the 90-day study period. Solutions stored in glass vials at controlled room temperature maintained at least 92% of initial potency throughout the 180-day study period. Visual and pH tests revealed stable, clear, colorless, and particulate-free solutions throughout the respective study periods.

Self-assembled novel multi-porphyrin micro-crystals as a photocatalyst for 2,4,6-trinitrotoluene degradation

NASA Astrophysics Data System (ADS)

Hikal, Walid M.

In this thesis I have presented the findings of my research pursued during my Ph.D. study. Following the findings that 2,4,6-trinitrotoluene binds to porphyrins at room temperature and could be photoctalytically degraded using porphyrin solutions and visible light, the purpose of this work was to determine the nature of the binding between the two species and develop a solid porphyrin-based photocatalyst for TNT degradation. C1TPP porphyrin is found to be able to bind to TNT via 1.94 kcal/mole hydrogen bonds at room temperature and hydrophobic bonds at higher temperatures. Photocatalytic solid porphyrin crystalline structures have been developed using two oppositely charged, commercially available, and low cost porphyrins in presence and absence of PAMAM generation 4 (G4) dendrimer, by self-assembly at room temperature without acidification. Solid porphyrin crystals were characterized by means of optical microscopy, UV-visible spectroscopy, fluorescence spectroscopy, and powder X-ray diffraction. A hypothetical model for the structure of the crystals is proposed. The porphyrin crystals show photocatalytic capabilities; illumination of the crystals in a 2,4,6-trinitrotoluene solution by visible light results in degradation of TNT and the intermediates have been determined using high pressure liquid chromatography (HPLC) and gas chromatography (GC).

Effect of rigor temperature, ageing and display time on the meat quality and lipid oxidative stability of hot boned beef Semimembranosus muscle.

PubMed

Mungure, Tanyaradzwa E; Bekhit, Alaa El-Din A; Birch, E John; Stewart, Ian

2016-04-01

The effects of rigor temperature (5, 15, 20 and 25°C), ageing (3, 7, 14, and 21 days) and display time on meat quality and lipid oxidative stability of hot boned beef M. Semimembranosus (SM) muscle were investigated. Ultimate pH (pH(u)) was rapidly attained at higher rigor temperatures. Electrical conductivity increased with rigor temperature (p<0.001). Tenderness, purge and cooking losses were not affected by rigor temperature; however purge loss and tenderness increased with ageing (p<0.01). Lightness (L*) and redness (a*) of the SM increased as rigor temperature increased (p<0.01). Lipid oxidation was assessed using (1)H NMR where changes in aliphatic to olefinic (R(ao)) and diallylmethylene (R(ad)) proton ratios can be rapidly monitored. R(ad), R(ao), PUFA and TBARS were not affected by rigor temperature, however ageing and display increased lipid oxidation (p<0.05). This study shows that rigor temperature manipulation of hot boned beef SM muscle does not have adverse effects on lipid oxidation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Six Month In Situ High-Resolution Carbonate Chemistry and Temperature Study on a Coral Reef Flat Reveals Asynchronous pH and Temperature Anomalies.

PubMed

Kline, David I; Teneva, Lida; Hauri, Claudine; Schneider, Kenneth; Miard, Thomas; Chai, Aaron; Marker, Malcolm; Dunbar, Rob; Caldeira, Ken; Lazar, Boaz; Rivlin, Tanya; Mitchell, Brian Gregory; Dove, Sophie; Hoegh-Guldberg, Ove

2015-01-01

Understanding the temporal dynamics of present thermal and pH exposure on coral reefs is crucial for elucidating reef response to future global change. Diel ranges in temperature and carbonate chemistry parameters coupled with seasonal changes in the mean conditions define periods during the year when a reef habitat is exposed to anomalous thermal and/or pH exposure. Anomalous conditions are defined as values that exceed an empirically estimated threshold for each variable. We present a 200-day time series from June through December 2010 of carbonate chemistry and environmental parameters measured on the Heron Island reef flat. These data reveal that aragonite saturation state, pH, and pCO2 were primarily modulated by biologically-driven changes in dissolved organic carbon (DIC) and total alkalinity (TA), rather than salinity and temperature. The largest diel temperature ranges occurred in austral spring, in October (1.5 - 6.6°C) and lowest diel ranges (0.9 - 3.2°C) were observed in July, at the peak of winter. We observed large diel total pH variability, with a maximum range of 7.7 - 8.5 total pH units, with minimum diel average pH values occurring during spring and maximum during fall. As with many other reefs, the nighttime pH minima on the reef flat were far lower than pH values predicted for the open ocean by 2100. DIC and TA both increased from June (end of Fall) to December (end of Spring). Using this high-resolution dataset, we developed exposure metrics of pH and temperature individually for intensity, duration, and severity of low pH and high temperature events, as well as a combined metric. Periods of anomalous temperature and pH exposure were asynchronous on the Heron Island reef flat, which underlines the importance of understanding the dynamics of co-occurrence of multiple stressors on coastal ecosystems.

Six Month In Situ High-Resolution Carbonate Chemistry and Temperature Study on a Coral Reef Flat Reveals Asynchronous pH and Temperature Anomalies

PubMed Central

Kline, David I.; Teneva, Lida; Hauri, Claudine; Schneider, Kenneth; Miard, Thomas; Chai, Aaron; Marker, Malcolm; Dunbar, Rob; Caldeira, Ken; Lazar, Boaz; Rivlin, Tanya; Mitchell, Brian Gregory; Dove, Sophie; Hoegh-Guldberg, Ove

2015-01-01

Understanding the temporal dynamics of present thermal and pH exposure on coral reefs is crucial for elucidating reef response to future global change. Diel ranges in temperature and carbonate chemistry parameters coupled with seasonal changes in the mean conditions define periods during the year when a reef habitat is exposed to anomalous thermal and/or pH exposure. Anomalous conditions are defined as values that exceed an empirically estimated threshold for each variable. We present a 200-day time series from June through December 2010 of carbonate chemistry and environmental parameters measured on the Heron Island reef flat. These data reveal that aragonite saturation state, pH, and pCO2 were primarily modulated by biologically-driven changes in dissolved organic carbon (DIC) and total alkalinity (TA), rather than salinity and temperature. The largest diel temperature ranges occurred in austral spring, in October (1.5 – 6.6°C) and lowest diel ranges (0.9 – 3.2°C) were observed in July, at the peak of winter. We observed large diel total pH variability, with a maximum range of 7.7 – 8.5 total pH units, with minimum diel average pH values occurring during spring and maximum during fall. As with many other reefs, the nighttime pH minima on the reef flat were far lower than pH values predicted for the open ocean by 2100. DIC and TA both increased from June (end of Fall) to December (end of Spring). Using this high-resolution dataset, we developed exposure metrics of pH and temperature individually for intensity, duration, and severity of low pH and high temperature events, as well as a combined metric. Periods of anomalous temperature and pH exposure were asynchronous on the Heron Island reef flat, which underlines the importance of understanding the dynamics of co-occurrence of multiple stressors on coastal ecosystems. PMID:26039687

Control of continuous phase PH using visible light to activate PH-dependent fibers and gels in a controlled and reversible manner

NASA Astrophysics Data System (ADS)

Zirino, Albert

1994-08-01

A transparent polyelectrolyte fiber or gel, such as crosslinked polyacrylic acid, which contracts and expands upon the addition of an acid or base to an aqueous medium solution, is placed in the same solution with a pH dependent dye, a colored photochromatic indicator dye. The dye preferably has a pAa value that is the same as the pH at a null contraction point of the fiber. By irradiating the solution with light of a wavelength of the absorption band of either the acid or base form of the dye, the solution pH is made to change, and the fiber is made to expand or contract, depending upon the wavelength. Thus, light energy is readily converted to work energy and may be used to power a pump, for example or an artificial muscle can be powered via an optical fiber.

Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

NASA Astrophysics Data System (ADS)

Pančić, M.; Hansen, P. J.; Tammilehto, A.; Lundholm, N.

2015-07-01

The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5, and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by ~ 20-50 % depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20-37 % compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

Resilience to temperature and pH changes in a future climate change scenario in six strains of the polar diatom Fragilariopsis cylindrus

NASA Astrophysics Data System (ADS)

Pančić, M.; Hansen, P. J.; Tammilehto, A.; Lundholm, N.

2015-03-01

The effects of ocean acidification and increased temperature on physiology of six strains of the polar diatom Fragilariopsis cylindrus from Greenland were investigated. Experiments were performed under manipulated pH levels (8.0, 7.7, 7.4, and 7.1) and different temperatures (1, 5 and 8 °C) to simulate changes from present to plausible future levels. Each of the 12 scenarios was run for 7 days, and a significant interaction between temperature and pH on growth was detected. By combining increased temperature and acidification, the two factors counterbalanced each other, and therefore no effect on the growth rates was found. However, the growth rates increased with elevated temperatures by ∼20-50% depending on the strain. In addition, a general negative effect of increasing acidification on growth was observed. At pH 7.7 and 7.4, the growth response varied considerably among strains. However, a more uniform response was detected at pH 7.1 with most of the strains exhibiting reduced growth rates by 20-37% compared to pH 8.0. It should be emphasized that a significant interaction between temperature and pH was found, meaning that the combination of the two parameters affected growth differently than when considering one at a time. Based on these results, we anticipate that the polar diatom F. cylindrus will be unaffected by changes in temperature and pH within the range expected by the end of the century. In each simulated scenario, the variation in growth rates among the strains was larger than the variation observed due to the whole range of changes in either pH or temperature. Climate change may therefore not affect the species as such, but may lead to changes in the population structure of the species, with the strains exhibiting high phenotypic plasticity, in terms of temperature and pH tolerance towards future conditions, dominating the population.

A gold nanocluster-based fluorescent probe for simultaneous pH and temperature sensing and its application to cellular imaging and logic gates.

PubMed

Wu, Yun-Tse; Shanmugam, Chandirasekar; Tseng, Wei-Bin; Hiseh, Ming-Mu; Tseng, Wei-Lung

2016-06-07

Metal nanocluster-based nanomaterials for the simultaneous determination of temperature and pH variations in micro-environments are still a challenge. In this study, we develop a dual-emission fluorescent probe consisting of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and fluorescein-5-isothiocyanate (FITC) as temperature- and pH-responsive fluorescence signals. Under single wavelength excitation the FITC/BSA-AuNCs exhibited well-separated dual emission bands at 525 and 670 nm. When FITC was used as a reference fluorophore, FITC/BSA-AuNCs showed a good linear response over the temperature range 1-71 °C and offered temperature-independent spectral shifts, temperature accuracy, activation energy, and reusability. The possible mechanism for high temperature-induced fluorescence quenching of FITC/BSA-AuNCs could be attributed to a weakening of the Au-S bond, thereby lowering the charge transfer from BSA to AuNCs. Additionally, the pH- and temperature-responsive properties of FITC/BSA-AuNCs allow simultaneous temperature sensing from 21 to 41 °C (at intervals of 5 °C) and pH from 6.0 to 8.0 (at intervals of 0.5 pH unit), facilitating the construction of two-input AND logic gates. Three-input AND logic gates were also designed using temperature, pH, and trypsin as inputs. The practicality of using FITC/BSA-AuNCs to determine the temperature and pH changes in HeLa cells is also validated.

Synthesis, morphology, optical and photocatalytic performance of nanostructured β-Ga{sub 2}O{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Girija, K.; DRDO – BU CLS, Bharathiar University, Coimbatore 641046; Thirumalairajan, S.

2013-06-01

Highlights: ► Nanostructures of β-Ga{sub 2}O{sub 3} were prepared using facile reflux condensation process. ► The pH of the reaction mixture shows evident influence on the size and shape of the nanostructures formed. ► The nanostructures exhibited good photocatalytic activity toward Rhodamine B and was found to be superior for higher pH value. - Abstract: Fine powders of β-Ga{sub 2}O{sub 3} nanostructures were prepared via low temperature reflux condensation method by varying the pH value without using any surfactant. The pH value of reaction mixture had great influence on the morphology of final products. High crystalline single phase β-Ga{sub 2}O{submore » 3} nanostructures were obtained by thermal treatment at 900 °C which was confirmed by X-ray diffraction and Raman spectroscopy. The morphological analysis revealed rod like nanostructures at lower and higher pH values of 6 and 10, while spindle like structures were obtained at pH = 8. The phase purity and presence of vibrational bands were identified using Fourier transform infrared spectroscopy. The optical absorbance spectrum showed intense absorption features in the UV spectral region. A broad blue emission peak centered at 441 nm due to donor–acceptor gallium–oxygen vacancy pair recombination appeared. The photocatalytic activity toward Rhodamine B under visible light irradiation was higher for nanorods at pH 10.« less

Electro deposition of cuprous oxide for thin film solar cell applications

NASA Astrophysics Data System (ADS)

Shahrestani, Seyed Mohammad

p and n type copper oxide semiconductor layers were fabricated by electrochemistry using new approaches for photovoltaic applications. Thin films were electroplated by cathodic polarization on a copper foil or indium tin oxide (ITO) substrates. The optimum deposition conditions (composition, pH and temperature of the electrolyte and applied potential) of the layers as thin films have been identified; in particular the conditions that allow getting the n-type layers have been well identified for the first time. The configuration of a photo - electrochemical cell was used to characterize the spectral response of the layers. It was shown that the p type layers exhibit a photocurrent in the cathode potential region and n layers exhibit photo current in the anode potential region. Measurements of electrical resistivity of electro chemically deposited layers of p and n type Cu2O, showed that the resistivity of p-type Cu2O varies from 3.2 x 105 to 2.0 x 108 Ocm. These values depend the electrodepositing conditions such as the pH of the solution, the deposition potential and temperature. The influence of several plating parameters of the p type layers of Cu2O, such as applied potential, pH and temperature of the bath on the chemical composition, degree of crystallinity, grain size and orientation parameters of the sample was systematically studied using X-ray diffraction and scanning electron microscopy. Depending of the electro-deposition potential, two different surface morphologies with various preferential crystal orientations were obtained for the temperatures of the electro-deposition of 30 °C and pH 9. For the same temperature, the layers of p type Cu2O of highly crystalline p type are obtained at pH 12, indicating that the crystallinity depends on the pH of the bath. Also, it has been shown that the morphology of Cu2O layers was changed by varying the potential and the duration of deposition, as well as the temperature of the solution. The conditions for the electro-deposition of Cu2O n-type were identified consistently for the first time. The electro-deposition electrolyte is based 0.01M acetate copper and 0.1 M sodium acetate: it has a pH between 6.3 and 4, a potential of from 0 to -0.25 V vs. Ag / AgCl and a temperature of 60oC. The optimum annealing temperature of the n-type Cu2O layers is between 120-150oC for the annealing time of 30 to 120 minutes. Resistivity of the n-type films varies between 5 x 103 and 5 x 104 at pH 4 to pH 6.4. We have shown for the first time that bubbling nitrogen gas in the electroplating cell improves significantly the spectral response of the electro-deposited n-type thin film. A two steps electro-deposition process was implemented to make the p-n homojunction cuprous oxide. Indium tin oxide (ITO) was used as a transparent conductive oxide substrate. A p-Cu2O was electrodeposited on ITO. After heat treatment a thin film layer of n-Cu 2O was electrodeposited on top of previous layer. The performance of a p-n homojunction photovoltaic solar cell of Cu2O was determined. The short-circuit current and the open circuit voltage were respectively determined to be as 0.35 volts and 235 muA/cm2. The fill factor (FF) and conversion efficiency of light into electricity were respectively measured to be 0.305 and 0.082%.

Ammonia gas permeability of meat packaging materials.

PubMed

Karim, Faris; Hijaz, Faraj; Kastner, Curtis L; Smith, J Scott

2011-03-01

Meat products are packaged in polymer films designed to protect the product from exterior contaminants such as light, humidity, and harmful chemicals. Unfortunately, there is almost no data on ammonia permeability of packaging films. We investigated ammonia permeability of common meat packaging films: low-density polyethylene (LDPE; 2.2 mil), multilayer polyolefin (MLP; 3 mil), and vacuum (V-PA/PE; 3 mil, 0.6 mil polyamide/2.4 mil polyethylene). The films were fabricated into 10 × 5 cm pouches and filled with 50 mL deionized water. Pouches were placed in a plexiglass enclosure in a freezer and exposed to 50, 100, 250, or 500 ppm ammonia gas for 6, 12, 24, and 48 h at -17 ± 3 °C and 21 ± 3 °C. At freezing temperatures, no ammonia residues were detected and no differences in pH were found in the water. At room temperature, ammonia levels and pH of the water increased significantly (P < 0.05) with increasing exposure times and ammonia concentrations. Average ammonia levels in the water were 7.77 ppm for MLP, 5.94 ppm for LDPE, and 0.89 ppm for V-PA/PE at 500 ppm exposure for 48 h at 21 ± 3 °C. Average pH values were 8.64 for MLP, 8.38 for LDPE, and 7.23 for V-PA/PE (unexposed ranged from 5.49 to 6.44) at 500 ppm exposure for 48 h. The results showed that temperature influenced ammonia permeability. Meat packaging materials have low ammonia permeability and protect meat products exposed to ammonia leaks during frozen storage.

Sulfur geochemistry of hydrothermal waters in Yellowstone National Park: IV Acid-sulfate waters

USGS Publications Warehouse

Nordstrom, D. Kirk; McCleskey, R. Blaine; Ball, J.W.

2009-01-01

Many waters sampled in Yellowstone National Park, both high-temperature (30-94 ??C) and low-temperature (0-30 ??C), are acid-sulfate type with pH values of 1-5. Sulfuric acid is the dominant component, especially as pH values decrease below 3, and it forms from the oxidation of elemental S whose origin is H2S in hot gases derived from boiling of hydrothermal waters at depth. Four determinations of pH were obtained: (1) field pH at field temperature, (2) laboratory pH at laboratory temperature, (3) pH based on acidity titration, and (4) pH based on charge imbalance (at both laboratory and field temperatures). Laboratory pH, charge imbalance pH (at laboratory temperature), and acidity pH were in close agreement for pH ??10%, a selection process was used to compare acidity, laboratory, and charge balance pH to arrive at the best estimate. Differences between laboratory and field pH can be explained based on Fe oxidation, H2S or S2O3 oxidation, CO2 degassing, and the temperature-dependence of pK2 for H2SO4. Charge imbalances are shown to be dependent on a speciation model for pH values 350 mg/L Cl) decrease as the Cl- concentration increases from boiling which appears inconsistent with the hypothesis of H2S oxidation as a source of hydrothermal SO4. This trend is consistent with the alternate hypothesis of anhydrite solubility equilibrium. Acid-sulfate water analyses are occasionally high in As, Hg, and NH3 concentrations but in contrast to acid mine waters they are low to below detection in Cu, Zn, Cd, and Pb concentrations. Even concentrations of SO4, Fe, and Al are much lower in thermal waters than acid mine waters of the same pH. This difference in water chemistry may explain why certain species of fly larvae live comfortably in Yellowstone's acid waters but have not been observed in acid rock drainage of the same pH.

Large Plant Growth Chambers: Flying Soon on a Space Station near You!

NASA Technical Reports Server (NTRS)

Massa, Gioia D.; Morrow, Robert C.; Levine, Howard G.

2014-01-01

The International Space Station (ISS) now has platforms for conducting research on horticultural plant species, and those capabilities continue to grow. The Veggie vegetable production system will be deployed to the ISS in Spring of 2014 to act as an applied research platform with goals of studying food production in space, providing the crew with a source of fresh food, allowing behavioral health and plant microbiology experimentation, and being a source of recreation and enjoyment for the crew. Veggie was conceived, designed, and constructed by Orbital Technologies Corporation (ORBITEC, Madison, WI). Veggie is the largest plant growth chamber that NASA has flown to date, and is capable of growing a wide array of horticultural crops. It was designed for low energy usage, low launch mass and stowage volume, and minimal crew time requirements. The Veggie flight hardware consists of a light cap containing red (630 nanometers), blue, (455 nanometers) and green (530 nanometers) light emitting diodes. Interfacing with the light cap is an extendable bellows baseplate secured to the light cap via magnetic closures and stabilized with extensible flexible arms. The baseplate contains vents allowing air from the ISS cabin to be pulled through the plant growth area by a fan in the light cap. The baseplate holds a Veggie root mat reservoir that will supply water to plant pillows attached via elastic cords. Plant pillows are packages of growth media and seeds that will be sent to ISS dry and installed and hydrated on orbit. Pillows can be constructed in various sizes for different plant types. Watering will be via passive wicking from the root mat to the pillows. Science procedures will include photography or videography, plant thinning, pollination, harvesting, microbial sampling, water sampling, etcetera. Veggie is one of the ISS flight options currently available for research investigations on plants. The Plant Habitat (PH) is being designed and constructed through a NASA-ORBITEC collaboration, and is scheduled to fly on ISS around 2016. This large plant chamber will control light quality, level, and timing, temperature, CO2, relative humidity, and irrigation, while scrubbing ethylene. Additional monitoring capabilities include leaf temperature sensing and root zone moisture and oxygen sensing. The PH light cap will have red (630 nanometers), blue (450 nanometers), green (525 nanometers), far red (730 nanometers) and broad spectrum white light emitting diodes. There will be several internal cameras to monitor and record plant growth and operations.

Compatibility and Stability of Rolapitant Injectable Emulsion Admixed with Intravenous Palonosetron Hydrochloride.

PubMed

Wu, George; Yeung, Stanley; Chen, Frank

2017-01-01

Neurokinin-1 receptor antagonist, 5-hydroxytryptamine-3 RA, and dexamethasone combination therapy is standard of care for the prevention of chemotherapy-induced nausea and vomiting. Herein we describe the physical and chemical stability of rolapitant injectable emulsion 166.5 mg in 92.5 mL (185 mg hydrochloride salt) admixed with palonosetron injection 0.25 mg in 5 mL (0.28 mg hydrochloride salt). Admixtures were prepared and stored in two types of container closures (110-mL Crystal Zenith plastic and glass bottles) and four types of intravenous administration sets (or intravenous tubing sets). Assessment of the physical and chemical stability was conducted on the admixtures in the ready-to-use container closure systems as supplied by the manufacturer, stored at room temperature (20°C to 25°C under fluorescent light), and evaluated at 0, 1, and 6 hours; 1 and 2 days; and under refrigeration (2°C to 8°C protected from light) after 1, 3, and 7 days. For admixtures in intravenous tubing sets, the assessment of physicochemical stability was performed after 0 and 7 hours of storage at 20°C to 25°C initially, and then after 20 hours (total 27 hours) at 2°C to 8°C protected from light. Physical stability was assessed by visual examination of the container contents under normal room light, and measuring turbidity and particulate matter. Chemical stability was assessed by measuring the pH of the admixture and determining drug concentrations and impurity levels with high-performance liquid chromatographic analysis. The results indicated that all samples were physically compatible throughout the duration of the study. The pH, turbidity, and particulate matter of the admixture stayed within narrow and acceptable ranges. Rolapitant admixed with palonosetron was chemically stable when admixed in glass and Crystal Zenith bottles for at least 48 hours at room temperature and for 7 days under refrigeration, as well as in the four selected intravenous tubing sets for 7 hours at 20°C to 25°C and then for 20 hours at 2°C to 8°C. No loss of potency of any admixed components occurred in the samples stored at the two temperature ranges and time period studied. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Facile Preparation of Light Emitting Organic Metal Halide Crystals with Near-Unity Quantum Efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Chenkun; Worku, Michael; Neu, Jennifer

Here, we report the synthesis and characterization of (Ph 4P) 2SbCl 5, a novel ionically bonded organic metal halide hybrid with a zero-dimensional (0D) structure at the molecular level. By cocrystallization of tetraphenylphosphonium (Ph 4P +) and antimony (Sb 3+) chloride salts, (Ph 4P) 2SbCl 5 bulk single crystals can be prepared in high yield, which exhibit a highly efficient broadband red emission peaked at 648 nm with a photoluminescence quantum efficiency (PLQE) of around 87%. Density functional theory (DFT) calculations reveal the origin of emission as phosphorescence from the excitons localized at SbCl 5 2– with strong excited-state structuralmore » distortion. Interestingly, (Ph 4P) 2SbCl 5 bulk crystals with a PLQE of around 100% can be prepared via a rapid crystal growth process within minutes, followed by a spontaneous structural transformation. It was found that the rapid growth process yielded a yellow emitting kinetically favored metastable product containing solvent molecules, which turned into the red emitting thermodynamically stable product slowly at room temperature or quickly upon thermal treatment.« less

Facile Preparation of Light Emitting Organic Metal Halide Crystals with Near-Unity Quantum Efficiency

DOE PAGES

Zhou, Chenkun; Worku, Michael; Neu, Jennifer; ...

2018-03-12

Here, we report the synthesis and characterization of (Ph 4P) 2SbCl 5, a novel ionically bonded organic metal halide hybrid with a zero-dimensional (0D) structure at the molecular level. By cocrystallization of tetraphenylphosphonium (Ph 4P +) and antimony (Sb 3+) chloride salts, (Ph 4P) 2SbCl 5 bulk single crystals can be prepared in high yield, which exhibit a highly efficient broadband red emission peaked at 648 nm with a photoluminescence quantum efficiency (PLQE) of around 87%. Density functional theory (DFT) calculations reveal the origin of emission as phosphorescence from the excitons localized at SbCl 5 2– with strong excited-state structuralmore » distortion. Interestingly, (Ph 4P) 2SbCl 5 bulk crystals with a PLQE of around 100% can be prepared via a rapid crystal growth process within minutes, followed by a spontaneous structural transformation. It was found that the rapid growth process yielded a yellow emitting kinetically favored metastable product containing solvent molecules, which turned into the red emitting thermodynamically stable product slowly at room temperature or quickly upon thermal treatment.« less

The behavior of rare earth elements in naturally and anthropogenically acidified waters

USGS Publications Warehouse

Wood, Scott A.; Gammons, Christopher H.; Parker, Stephen R.

2006-01-01

In this paper, the behavior of rare earth elements (REE) in a watershed impacted by acid-mine drainage (Fisher Creek, Montana) is compared to that in a volcanically acidified watershed (Rio Agrio and Lake Caviahue, Argentina). The REE behave conservatively in acidic waters with pH values less than approximately 5.5. However, above pH 5.5, REE concentrations are controlled by adsorption onto or co-precipitation with a variety of Fe or Al oxyhydroxides. The heavy REE partition to a greater extent into the solid phase than the light REE as pH rises above 6. Concentrations of REE exhibit diel (24-h) cycling in waters that were initially acidic, but have become neutralized downstream. In Fisher Creek, at the most downstream sampling station investigated (pH 6.8), concentrations of dissolved REE were 190–840% higher in the early morning versus the late afternoon. This cycling can be related to temperature-dependent, cyclic adsorption–desorption of REE onto hydrous ferric or aluminum oxide or both. Similar but gentler diel cycling of the REE was found at Rio Agrio. The existence of such cycling has important ramifications for the study of REE in natural waters.

Structural Characterization of Apomyoglobin Self-Associated Species in Aqueous Buffer and Urea Solution

PubMed Central

Chow, Charles; Kurt, Neşe; Murphy, Regina M.; Cavagnero, Silvia

2006-01-01

The biophysical characterization of nonfunctional protein aggregates at physiologically relevant temperatures is much needed to gain deeper insights into the kinetic and thermodynamic relationships between protein folding and misfolding. Dynamic and static laser light scattering have been employed for the detection and detailed characterization of apomyoglobin (apoMb) soluble aggregates populated at room temperature upon dissolving the purified protein in buffer at pH 6.0, both in the presence and absence of high concentrations of urea. Unlike the β-sheet self-associated aggregates previously reported for this protein at high temperatures, the soluble aggregates detected here have either α-helical or random coil secondary structure, depending on solvent and solution conditions. Hydrodynamic diameters range from 80 to 130 nm, with semiflexible chain-like morphology. The combined use of low pH and high urea concentration leads to structural unfolding and complete elimination of the large aggregates. Even upon starting from this virtually monomeric unfolded state, however, protein refolding leads to the formation of severely self-associated species with native-like secondary structure. Under these conditions, kinetic apoMb refolding proceeds via two parallel routes: one leading to native monomer, and the other leading to a misfolded and heavily self-associated state bearing native-like secondary structure. PMID:16214860

Influence of the hydrothermal temperature and pH on the crystallinity of a sputtered hydroxyapatite film

NASA Astrophysics Data System (ADS)

Ozeki, K.; Aoki, H.; Masuzawa, T.

2010-09-01

Hydroxyapatite (HA) was coated onto titanium substrates using radio frequency sputtering, and the sputtered films were crystallized under hydrothermal conditions at 110-170 °C at pH values of 7.0 and 9.5. The crystallite size, the remnant film thickness, and the surface morphology of the films were observed using X-ray diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy, respectively. The crystallite size increased with the process temperature, and reached 123.6 nm (pH 9.5 and 170 °C) after 24 h. All of the crystallite sizes of the film treated at pH 9.5 were higher than those treated at pH 7.0 at each process temperature. The film treated at pH 9.5 retained more than 90% of the initial film thickness at any process temperature. The ratio of the film treated at pH 7.0 did not reached 90% at less than 150 °C, and tended to increase with the process temperature.

Enhanced Light Extraction from OLEDs Fabricated on Patterned Plastic Substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hippola, Chamika; Kaudal, Rajiv; Manna, Eeshita

A key scientific and technological challenge in organic light-emitting diodes (OLEDs) is enhancing the light outcoupling factor η out, which is typically <20%. This paper reports experimental and modeling results of a promising approach to strongly increase η out by fabricating OLEDs on novel flexible nanopatterned substrates that result in a >2× enhancement in green phosphorescent OLEDs (PhOLEDs) fabricated on corrugated polycarbonate (PC). The external quantum efficiency (EQE) reaches 50% (meaning ηout ≥50%); it increases 2.6x relative to a glass/ITO device and 2× relative to devices on glass/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) or flat PC/PEDOT:PSS. A significant enhancement is also observed formore » blue PhOLEDs with EQE 1.7× relative to flat PC. The corrugated PC substrates are fabricated efficiently and cost-effectively by direct room-temperature molding. These substrates successfully reduce photon losses due to trapping/waveguiding in the organic+anode layers and possibly substrate, and losses to plasmons at the metal cathode. Focused ion beam gauged the conformality of the OLEDs. Dome-shaped convex nanopatterns with height of ~280–400 nm and pitch ~750–800 nm were found to be optimal. Lastly, substrate design and layer thickness simulations, reported first for patterned devices, agree with the experimental results that present a promising method to mitigate photon loss paths in OLEDs.« less

Enhanced Light Extraction from OLEDs Fabricated on Patterned Plastic Substrates

DOE PAGES

Hippola, Chamika; Kaudal, Rajiv; Manna, Eeshita; ...

2018-02-19

A key scientific and technological challenge in organic light-emitting diodes (OLEDs) is enhancing the light outcoupling factor η out, which is typically <20%. This paper reports experimental and modeling results of a promising approach to strongly increase η out by fabricating OLEDs on novel flexible nanopatterned substrates that result in a >2× enhancement in green phosphorescent OLEDs (PhOLEDs) fabricated on corrugated polycarbonate (PC). The external quantum efficiency (EQE) reaches 50% (meaning ηout ≥50%); it increases 2.6x relative to a glass/ITO device and 2× relative to devices on glass/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) or flat PC/PEDOT:PSS. A significant enhancement is also observed formore » blue PhOLEDs with EQE 1.7× relative to flat PC. The corrugated PC substrates are fabricated efficiently and cost-effectively by direct room-temperature molding. These substrates successfully reduce photon losses due to trapping/waveguiding in the organic+anode layers and possibly substrate, and losses to plasmons at the metal cathode. Focused ion beam gauged the conformality of the OLEDs. Dome-shaped convex nanopatterns with height of ~280–400 nm and pitch ~750–800 nm were found to be optimal. Lastly, substrate design and layer thickness simulations, reported first for patterned devices, agree with the experimental results that present a promising method to mitigate photon loss paths in OLEDs.« less

Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements.

PubMed

Rérolle, Victoire M C; Floquet, Cedric F A; Harris, Andy J K; Mowlem, Matt C; Bellerby, Richard R G J; Achterberg, Eric P

2013-07-05

High quality carbonate chemistry measurements are required in order to fully understand the dynamics of the oceanic carbonate system. Seawater pH data with good spatial and temporal coverage are particularly critical to apprehend ocean acidification phenomena and their consequences. There is a growing need for autonomous in situ instruments that measure pH on remote platforms. Our aim is to develop an accurate and precise autonomous in situ pH sensor for long term deployment on remote platforms. The widely used spectrophotometric pH technique is capable of the required high-quality measurements. We report a key step towards the miniaturization of a colorimetric pH sensor with the successful implementation of a simple microfluidic design with low reagent consumption. The system is particularly adapted to shipboard deployment: high quality data was obtained over a period of more than a month during a shipboard deployment in northwest European shelf waters, and less than 30 mL of indicator was consumed. The system featured a short term precision of 0.001 pH (n=20) and an accuracy within the range of a certified Tris buffer (0.004 pH). The quality of the pH system measurements have been checked using various approaches: measurements of certified Tris buffer, measurement of certified seawater for DIC and TA, comparison of measured pH against calculated pH from pCO2, DIC and TA during the cruise in northwest European shelf waters. All showed that our measurements were of high quality. The measurements were made close to in situ temperature (+0.2°C) in a sampling chamber which had a continuous flow of the ship's underway seawater supply. The optical set up was robust and relatively small due to the use of an USB mini-spectrometer, a custom made polymeric flow cell and an LED light source. The use of a three wavelength LED with detection that integrated power across the whole of each LED output spectrum indicated that low wavelength resolution detectors can be used instead of the current USB mini spectrophotometer. Artefacts due to the polychromatic light source and inhomogeneity in the absorption cell are shown to have a negligible impact on the data quality. The next step in the miniaturization of the sensor will be the incorporation of a photodiode as detector to replace the spectrophotometer. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

LC-mS analysis of human urine specimens for 2-oxo-3-hydroxy LSD: method validation for potential interferants and stability study of 2-oxo-3-hydroxy LSD under various storage conditions.

PubMed

Klette, Kevin L; Horn, Carl K; Stout, Peter R; Anderson, Cynthia J

2002-01-01

2-Oxo-3-hydroxy lysergic acid diethylamide (O-H-LSD), a major LSD metabolite, has previously been demonstrated to be a superior marker for identifying LSD use compared with the parent drug, LSD. Specifically, O-H-LSD analyzed using liquid chromatography-mass spectrometry has been reported to be present in urine at concentrations 16 to 43 times greater than LSD. To further support forensic application of this procedure, the specificity of the assay was assessed using compounds that have structural and chemical properties similar to O-H-LSD, common over-the-counter products, prescription drugs and some of their metabolites, and other drugs of abuse. Of the wide range of compounds studied, none were found to interfere with the detection of O-H-LSD or the internal standard 2-oxo-3-hydroxy lysergic acid methyl propylamide. The stability of O-H-LSD was investigated from 0 to 9 days at various temperatures, pH conditions, and exposures to fluorescent light. Additionally, the effect of long-term frozen storage and pH was investigated from 0 to 60 days. There was no significant loss of O-H-LSD under both refrigerated and frozen conditions within the normal human physiological pH range of urine (4.6-8.4). However, significant loss of O-H-LSD was observed in samples prepared at pH 4.6-8.4 and stored at room temperature or higher (24-50 degrees C).

Development of an autonomous, wireless pH and temperature sensing system for monitoring pig meat quality.

PubMed

Frisby, June; Raftery, Declan; Kerry, Joe P; Diamond, Dermot

2005-06-01

This paper focuses on the development of a unique wireless pH and temperature monitoring system to assess pig meat quality. Pale, soft and exudative (PSE) pig meat continues to be a major problem in the pig meat industry today. The PSE condition in pork is related to a number of factors including genetics, pre-slaughter stress and insufficient chilling of pig carcasses, which cause a rapid rate of glycolysis post-mortem (<1h). As a result the pH drops to low levels while the muscle temperature is still high. A wireless dual channel system that monitors pH and temperature simultaneously has been developed to provide pH and temperature data of the carcass during the first 24h after slaughter. We have demonstrated that this approach can distinguish in real time, pH and temperature profiles that are 'non-normal', and identify carcasses that are PSE positive quickly and easily.

Effects of Temperature on Bacterial Communities and Metabolites during Fermentation of Myeolchi-Aekjeot, a Traditional Korean Fermented Anchovy Sauce

PubMed Central

Chun, Byung Hee; Jeon, Che Ok

2016-01-01

Myeolchi-aekjeot (MA) in Korea is produced outdoors without temperature controls, which is a major obstacle to produce commercial MA products with uniform quality. To investigate the effects of temperature on MA fermentation, pH, bacterial abundance and community, and metabolites were monitored during fermentation at 15°C, 20°C, 25°C, and 30°C. Initial pH values were approximately 6.0, and pH values increased after approximately 42 days, with faster increases at higher temperatures. Bacterial abundances increased rapidly in all MA samples after quick initial decreases during early fermentation and then they again steadily decreased after reaching their maxima, which were significantly greater at higher temperatures. Bacterial community analysis revealed that Proteobacteria and Tenericutes were predominant in all initial MA samples, but they were rapidly displaced by Firmicutes as fermentation progressed. Photobacterium and Mycoplasma belonging to Proteobacteria and Tenericutes, respectively, which may include potentially pathogenic strains, were dominant in initial MA, but decreased with the growth of Chromohalobacter, which occurred faster at higher temperatures––they were dominant until 273 and 100 days at 15°C and 20°C, respectively, but not detected after 30 days at 25°C and 30°C. Chromohalobacter also decreased with the appearance of subsequent genera belonging to Firmicutes in all MA samples. Tetragenococcus, halophilic lactic acid bacteria, appeared predominantly at 20°C, 25°C, and 30°C; they were most abundant at 30°C, but not detected at 15°C. Alkalibacillus and Lentibacillus appeared as dominant genera with the decrease of Tetragenococcus at 25°C and 30°C, but only Lentibacillus was dominant at 15°C and 20°C. Metabolite analysis showed that amino acids related to tastes were major metabolites and their concentrations were relatively higher at high temperatures. This study suggests that high temperatures (approximately 30°C) may be appropriate in MA fermentation, in the light of faster disappearance of potentially pathogenic genera, higher amino acids, growth of Tetragenococcus, and faster fermentation. PMID:26977596

Initial steps in defining the environment of the prepuce of the bull by measuring pH and temperature.

PubMed

Koziol, J H; Fraser, N S; Passler, T; Wolfe, D F

2017-12-01

To determine the baseline pH and temperature of the preputial cavity of bulls. We enrolled 55 bulls ranging in age from 15 to 84 months. The preputial temperature and pH were measured by insertion of temperature and pH probes, respectively, into the preputial orifice prior to routine breeding soundness examinations. Information was obtained from owners regarding the diet of each bull and categorised as one of three categories: forage only, grain supplemented or silage supplemented. The average temperature of the prepuce was 37.81°C ± 1.76 and the median pH of the prepuce was 8.45 (6.35-9.46). Preputial temperatures of the bull weakly correlated with ambient temperatures (r s  = -0.29, P = 0.028). The preputial pH of silage-fed bulls was significantly lower than that of bulls fed forage only (P = 0.025) or grain-supplemented diets (P = 0.002). The median preputial pH of bulls fed a silage-based diet was 7.6 (6.3-8.9) compared with a median pH 8.7 (7.8-9.1) for bulls fed forage-based diets or a median of 8.5 (7.7-9.4) for those given grain-supplemented diets. Diet and ambient temperature can, respectively, affect pH and the temperature in the prepuce. Further studies to describe and understand the microbiota of the prepuce and penis may assist in developing treatments for diseases of the genital tract in bulls. © 2017 Australian Veterinary Association.

Temperature-Responsive Smart Nanocarriers for Delivery Of Therapeutic Agents: Applications and Recent Advances.

PubMed

Karimi, Mahdi; Sahandi Zangabad, Parham; Ghasemi, Alireza; Amiri, Mohammad; Bahrami, Mohsen; Malekzad, Hedieh; Ghahramanzadeh Asl, Hadi; Mahdieh, Zahra; Bozorgomid, Mahnaz; Ghasemi, Amir; Rahmani Taji Boyuk, Mohammad Reza; Hamblin, Michael R

2016-08-24

Smart drug delivery systems (DDSs) have attracted the attention of many scientists, as carriers that can be stimulated by changes in environmental parameters such as temperature, pH, light, electromagnetic fields, mechanical forces, etc. These smart nanocarriers can release their cargo on demand when their target is reached and the stimulus is applied. Using the techniques of nanotechnology, these nanocarriers can be tailored to be target-specific, and exhibit delayed or controlled release of drugs. Temperature-responsive nanocarriers are one of most important groups of smart nanoparticles (NPs) that have been investigated during the past decades. Temperature can either act as an external stimulus when heat is applied from the outside, or can be internal when pathological lesions have a naturally elevated termperature. A low critical solution temperature (LCST) is a special feature of some polymeric materials, and most of the temperature-responsive nanocarriers have been designed based on this feature. In this review, we attempt to summarize recent efforts to prepare innovative temperature-responsive nanocarriers and discuss their novel applications.

Compatibility and Stability of Rolapitant Injectable Emulsion Admixed with Dexamethasone Sodium Phosphate.

PubMed

Wu, George; Yeung, Stanley; Chen, Frank

2017-01-01

Neurokinin-1 receptor antagonist, 5-hydroxytryptamine-3 receptor antagonist, and dexamethasone combination therapy is the standard of care for the prevention of chemotherapy-induced nausea and vomiting. Herein, we describe the physical and chemical stability of an injectable emulsion of the Neurokinin-1 receptor antagonist rolapitant 185 mg in 92.5 mL (free base, 166.5 mg in 92.5 mL) admixed with either 2.5 mL of dexamethasone sodium phosphate (10 mg) or 5 mL of dexamethasone sodium phosphate (20 mg). Admixtures were prepared and stored in two types of container closures (glass and Crystal Zenith plastic bottles) and four types of intravenous administration tubing sets (or intravenous tubing sets). The assessment of the physical and chemical stability was conducted on admixtures packaged in bottled samples stored at room temperature (20°C to 25°C under fluorescent light) and evaluated at 0, 1, and 6 hours. For admixtures in intravenous tubing sets, the assessment of physicochemical stability was performed after 0 and 7 hours of storage at 20°C to 25°C, and then after 20 hours (total 27 hours) under refrigeration (2°C to 8°C) and protected from light. Physical stability was assessed by visually examining the bottle contents under normal room light and measuring turbidity and particulate matter. Chemical stability was assessed by measuring the pH of the admixture and determining drug concentrations through high-performance liquid chromatographic analysis. Results showed that all samples were physically compatible throughout the duration of the study. The admixtures stayed within narrow and acceptable ranges in pH, turbidity, and particulate matter. Admixtures of rolapitant and dexamethasone were chemically stable when stored in glass and Crystal Zenith bottles for at least 6 hours at room temperature, as well as in the four selected intravenous tubing sets for 7 hours at 20°C to 25°C and then for 20 (total 27 hours) hours at 2°C to 8°C. No loss of potency of any admixed component occurred in the samples stored at the temperature ranges studied. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Extraction of anthocyanins and polyphenols from black rice (Oryza sativa L.) by modeling and assessing their reversibility and stability.

PubMed

Pedro, Alessandra Cristina; Granato, Daniel; Rosso, Neiva Deliberali

2016-01-15

This study was aimed the extraction of total flavonoids, anthocyanins and phenolics, as well as the antioxidant activity of black rice (Oryza sativa) and to study the stability in relation to pH, light and copigmentation. Variations in temperature (10-50°C), time (20-80min), and solid-solvent ratio (1:15-1:45) were studied using a Box-Behnken design. The regression models were significant (P<0.001) and determination coefficients ⩾0.900. Extraction at 34.7°C for 80min using a solid:solvent ratio of 1:30 rendered an extract with 51.26mg 100g(-1) of flavonoids, 116.58mg 100g(-1) of anthocyanins, 520.17mg 100g(-1) of phenolics and 46.50% inhibition of the DPPH radical. A decrease in the color intensity was observed when pH values were changed while anthocyanins were reversible in the process of protonation/deprotonation. The addition of glucose, phytic and gallic acids in the optimized extract exposed to light displayed an intermolecular copigmentation. The main anthocyanin identified in black rice was cyanidin-3-glucoside. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biotic Control of Surface pH and Evidence of Light-Induced H+ Pumping and Ca2+-H+ Exchange in a Tropical Crustose Coralline Alga.

PubMed

Hofmann, Laurie C; Koch, Marguerite; de Beer, Dirk

2016-01-01

Presently, an incomplete mechanistic understanding of tropical reef macroalgae photosynthesis and calcification restricts predictions of how these important autotrophs will respond to global change. Therefore, we investigated the mechanistic link between inorganic carbon uptake pathways, photosynthesis and calcification in a tropical crustose coralline alga (CCA) using microsensors. We measured pH, oxygen (O2), and calcium (Ca2+) dynamics and fluxes at the thallus surface under ambient (8.1) and low (7.8) seawater pH (pHSW) and across a range of irradiances. Acetazolamide (AZ) was used to inhibit extracellular carbonic anhydrase (CAext), which mediates hydrolysis of HCO3-, and 4,4' diisothiocyanatostilbene-2,2'-disulphonate (DIDS) that blocks direct HCO3- uptake by anion exchange transport. Both inhibited photosynthesis, suggesting both diffusive uptake of CO2 via HCO3- hydrolysis to CO2 and direct HCO3- ion transport are important in this CCA. Surface pH was raised approximately 0.3 units at saturating irradiance, but less when CAext was inhibited. Surface pH was lower at pHSW 7.8 than pHSW 8.1 in the dark, but not in the light. The Ca2+ fluxes were large, complex and temporally variable, but revealed net Ca2+ uptake under all conditions. The temporal variability in Ca2+ dynamics was potentially related to localized dissolution during epithallial cell sloughing, a strategy of CCA to remove epiphytes. Simultaneous Ca2+ and pH dynamics suggest the presence of Ca2+/H+ exchange. Rapid light-induced H+ surface dynamics that continued after inhibition of photosynthesis revealed the presence of a light-mediated, but photosynthesis-independent, proton pump. Thus, the study indicates metabolic control of surface pH can occur in CCA through photosynthesis and light-inducible H+ pumps. Our results suggest that complex light-induced ion pumps play an important role in biological processes related to inorganic carbon uptake and calcification in CCA.

Biotic Control of Surface pH and Evidence of Light-Induced H+ Pumping and Ca2+-H+ Exchange in a Tropical Crustose Coralline Alga

PubMed Central

Hofmann, Laurie C.; Koch, Marguerite; de Beer, Dirk

2016-01-01

Presently, an incomplete mechanistic understanding of tropical reef macroalgae photosynthesis and calcification restricts predictions of how these important autotrophs will respond to global change. Therefore, we investigated the mechanistic link between inorganic carbon uptake pathways, photosynthesis and calcification in a tropical crustose coralline alga (CCA) using microsensors. We measured pH, oxygen (O2), and calcium (Ca2+) dynamics and fluxes at the thallus surface under ambient (8.1) and low (7.8) seawater pH (pHSW) and across a range of irradiances. Acetazolamide (AZ) was used to inhibit extracellular carbonic anhydrase (CAext), which mediates hydrolysis of HCO3-, and 4,4′ diisothiocyanatostilbene-2,2′-disulphonate (DIDS) that blocks direct HCO3- uptake by anion exchange transport. Both inhibited photosynthesis, suggesting both diffusive uptake of CO2 via HCO3- hydrolysis to CO2 and direct HCO3- ion transport are important in this CCA. Surface pH was raised approximately 0.3 units at saturating irradiance, but less when CAext was inhibited. Surface pH was lower at pHSW 7.8 than pHSW 8.1 in the dark, but not in the light. The Ca2+ fluxes were large, complex and temporally variable, but revealed net Ca2+ uptake under all conditions. The temporal variability in Ca2+ dynamics was potentially related to localized dissolution during epithallial cell sloughing, a strategy of CCA to remove epiphytes. Simultaneous Ca2+ and pH dynamics suggest the presence of Ca2+/H+ exchange. Rapid light-induced H+ surface dynamics that continued after inhibition of photosynthesis revealed the presence of a light-mediated, but photosynthesis-independent, proton pump. Thus, the study indicates metabolic control of surface pH can occur in CCA through photosynthesis and light-inducible H+ pumps. Our results suggest that complex light-induced ion pumps play an important role in biological processes related to inorganic carbon uptake and calcification in CCA. PMID:27459463

Simultaneous wireless assessment of intra-oral pH and temperature.

PubMed

Farella, M; Loke, C; Sander, S; Songini, A; Allen, M; Mei, L; Cannon, R D

2016-08-01

Intra-oral pH plays an important role in the pathogenesis of tooth erosion and decay, but there is limited information about its variation in real life settings. The aims of this research were to: 1) develop a wireless device, which can be used to continuously monitor intra-oral pH and temperature in real-time; 2) test and validate the device under controlled laboratory conditions; and 3) collect data in a natural environment in a sample of healthy volunteers. A wireless device for measuring pH and temperature simultaneously was developed, calibrated and validated against the gold standard glass electrode pH meter. A smart phone was used as data logger. The wireless device was embedded in an oral appliance and worn by eleven participants (mean age 31.1±6.9years) for 24h, while conducting standardised drinking tasks and regular daily activities. The wireless device could accurately measure pH and temperature both in vitro and in vivo. The recovery time following the swallow of a standard acidic drink varied markedly among individuals (mean=1.3±0.9min). The intra-oral pH and temperature recorded in the natural environment also showed a large inter- and intra-individual variability. The average intra-oral pH when asleep (6.7±0.5) was lower (p<0.001) than when awake (7.2±0.5). The average intra-oral temperature during sleep (35.6±0.5°C) was higher (p<0.001) than when awake (34.5±0.7°C). Intra-oral pH and temperature can be continuously and wirelessly assessed in real-life settings, and show individual-specific patterns with circadian variations. Intra-oral pH becomes slightly acidic during sleep while intra-oral temperature increases and fluctuates less. We propose a wireless device that is capable of measuring intra-oral pH over a 24-h period. We found marked inter-individual variation after acidic stimuli, and day to sleep time variation of both intra-oral temperature and pH. Our approach may provide new insight into the relationship between oral pH, tooth wear and decay. Copyright © 2016 Elsevier Ltd. All rights reserved.

Avian influenza virus (H5N1); effects of physico-chemical factors on its survival

PubMed Central

Shahid, Muhammad Akbar; Abubakar, Muhammad; Hameed, Sajid; Hassan, Shamsul

2009-01-01

Present study was performed to determine the effects of physical and chemical agents on infective potential of highly pathogenic avian influenza (HPAI) H5N1 (local strain) virus recently isolated in Pakistan during 2006 outbreak. H5N1 virus having titer 108.3 ELD50/ml was mixed with sterilized peptone water to get final dilution of 4HA units and then exposed to physical (temperature, pH and ultraviolet light) and chemical (formalin, phenol crystals, iodine crystals, CID 20, virkon®-S, zeptin 10%, KEPCIDE 300, KEPCIDE 400, lifebuoy, surf excel and caustic soda) agents. Harvested amnio-allantoic fluid (AAF) from embryonated chicken eggs inoculated with H5N1 treated virus (0.2 ml/egg) was subjected to haemagglutination (HA) and haemagglutination inhibition (HI) tests. H5N1 virus lost infectivity after 30 min at 56°C, after 1 day at 28°C but remained viable for more than 100 days at 4°C. Acidic pH (1, 3) and basic pH (11, 13) were virucidal after 6 h contact time; however virus retained infectivity at pH 5 (18 h), 7 and 9 (more than 24 h). UV light was proved ineffectual in inactivating virus completely even after 60 min. Soap (lifebuoy®), detergent (surf excel®) and alkali (caustic soda) destroyed infectivity after 5 min at 0.1, 0.2 and 0.3% dilution. All commercially available disinfectants inactivated virus at recommended concentrations. Results of present study would be helpful in implementing bio-security measures at farms/hatcheries levels in the wake of avian influenza virus (AIV) outbreak. PMID:19327163

Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 282 000 years

NASA Astrophysics Data System (ADS)

Ajioka, T.; Yamamoto, M.; Takemura, K.; Hayashida, A.

2014-03-01

We generated a 282 000-year record of water pH and temperature in Lake Biwa, central Japan, by analysing the methylation index (MBT') and cyclisation ratio (CBT) of branched tetraethers in sediments from piston and borehole cores to understand the responses of precipitation and air temperature in central Japan to the East Asian monsoon variability on the orbital timescale. Because water pH in Lake Biwa is determined by phosphorus input driven by precipitation, the record of water pH should indicate changes in summer precipitation in central Japan. The estimated pH showed significant periodicity at 19 and 23 ka (precession) and at 41 ka (obliquity). The variation in the estimated pH agrees with variation in the pollen temperature index. This indicates synchronous variation in summer air temperature and precipitation in central Japan, which contradicts the conclusions of previous studies. The variation in estimated pH was also synchronous with the variation of oxygen isotopes in stalagmites in China, suggesting that East Asian summer monsoon precipitation was governed by Northern Hemisphere summer insolation on orbital timescales. However, the estimated winter temperatures were higher during interglacials and lower during glacials, showing an eccentricity cycle. This suggests that the temperature variation reflected winter monsoon variability.

Modeling and predicting the biofilm formation of Salmonella Virchow with respect to temperature and pH.

PubMed

Ariafar, M Nima; Buzrul, Sencer; Akçelik, Nefise

2016-03-01

Biofilm formation of Salmonella Virchow was monitored with respect to time at three different temperature (20, 25 and 27.5 °C) and pH (5.2, 5.9 and 6.6) values. As the temperature increased at a constant pH level, biofilm formation decreased while as the pH level increased at a constant temperature, biofilm formation increased. Modified Gompertz equation with high adjusted determination coefficient (Radj(2)) and low mean square error (MSE) values produced reasonable fits for the biofilm formation under all conditions. Parameters of the modified Gompertz equation could be described in terms of temperature and pH by use of a second order polynomial function. In general, as temperature increased maximum biofilm quantity, maximum biofilm formation rate and time of acceleration of biofilm formation decreased; whereas, as pH increased; maximum biofilm quantity, maximum biofilm formation rate and time of acceleration of biofilm formation increased. Two temperature (23 and 26 °C) and pH (5.3 and 6.3) values were used up to 24 h to predict the biofilm formation of S. Virchow. Although the predictions did not perfectly match with the data, reasonable estimates were obtained. In principle, modeling and predicting the biofilm formation of different microorganisms on different surfaces under various conditions could be possible.

Diphosphine is an intermediate in the photolysis of phosphine to phosphorus and hydrogen. [Jupiter atmospheric chemistry

NASA Technical Reports Server (NTRS)

Ferris, J. P.; Benson, R.

1980-01-01

The photolysis of phosphine to red phosphorus (P4) and hydrogen is investigated in light of the potential significance of the reaction in the atmospheric chemistry of Jupiter. It is reported that the photolysis of PH3 at room temperature by a 206.2-nm light source gave rise to a product identified by its UV and IR spectra and gas chromatographic retention time as P2H4, the yield of which is found to increase to a maximum and then decrease to 20% of the maximum value with illumination time. A mechanism for phosphine photolysis including diphosphine formation as an intermediate step is proposed, and it is concluded that P2H4 is a likely constituent of the atmospheres of the Jovian planets.

Red Light-enhanced Phytochrome Pelletability

PubMed Central

Pratt, Lee H.; Marmé, Dieter

1976-01-01

Red light-enhanced pelletability of phytochrome was observed in extracts of all 11 plants tested: Avena sativa L., Secale cereale L., Zea mays L., Cucurbita pepo L., Sinapis alba L., Pisum sativum L., Helianthus anuus L., Raphanus sativus L., Glycine max (L.) Merr., Phaseolus vulgaris L., and Lupinus albus L. This enhanced pelletability was observed in all 11 plants following in situ irradiation (in vivo binding) but only in Sinapis and Cucurbita after irradiation of crude extracts (in vitro binding). In vivo binding was not strongly dependent upon pH and, with few exceptions, was not markedly sensitive to high salt concentration, whereas in vitro binding was completely reversed by both high pH and high salt concentration. However, both binding phenomena were observed only with a divalent cation in the extract buffer. In vivo binding was further characterized using Avena which showed an increase in pelletability from less than 10% in dark control extracts to more than 60% in extracts of red light-irradiated shoots. The half-life for binding was 40 seconds at 0.5 C and was strongly temperature-dependent, binding being complete within 5 to 10 sec at 22 C. If pelletable phytochrome in the far red-absorbing form was photoconverted back to the red-absorbing form in situ, phytochrome was released from the pelletable condition with a half-life of 25 minutes at 25 C and 100 minutes at both 13 C and 3 C. No cooperativity in red light-enhanced pelletability with respect to phytochrome-far red-absorbing form was observed. PMID:16659745

Protein delivery of a Ni catalyst to photosystem I for light-driven hydrogen production.

PubMed

Silver, Sunshine C; Niklas, Jens; Du, Pingwu; Poluektov, Oleg G; Tiede, David M; Utschig, Lisa M

2013-09-11

The direct conversion of sunlight into fuel is a promising means for the production of storable renewable energy. Herein, we use Nature's specialized photosynthetic machinery found in the Photosystem I (PSI) protein to drive solar fuel production from a nickel diphosphine molecular catalyst. Upon exposure to visible light, a self-assembled PSI-[Ni(P2(Ph)N2(Ph))2](BF4)2 hybrid generates H2 at a rate 2 orders of magnitude greater than rates reported for photosensitizer/[Ni(P2(Ph)N2(Ph))2](BF4)2 systems. The protein environment enables photocatalysis at pH 6.3 in completely aqueous conditions. In addition, we have developed a strategy for incorporating the Ni molecular catalyst with the native acceptor protein of PSI, flavodoxin. Photocatalysis experiments with this modified flavodoxin demonstrate a new mechanism for biohybrid creation that involves protein-directed delivery of a molecular catalyst to the reducing side of Photosystem I for light-driven catalysis. This work further establishes strategies for constructing functional, inexpensive, earth-abundant solar fuel-producing PSI hybrids that use light to rapidly produce hydrogen directly from water.

Activation of Phosphorylase Kinase by Physiological Temperature.

PubMed

Herrera, Julio E; Thompson, Jackie A; Rimmer, Mary Ashley; Nadeau, Owen W; Carlson, Gerald M

2015-12-29

In the six decades since its discovery, phosphorylase kinase (PhK) from rabbit skeletal muscle has usually been studied at 30 °C; in fact, not a single study has examined functions of PhK at a rabbit's body temperature, which is nearly 10 °C greater. Thus, we have examined aspects of the activity, regulation, and structure of PhK at temperatures between 0 and 40 °C. Between 0 and 30 °C, the activity at pH 6.8 of nonphosphorylated PhK predictably increased; however, between 30 and 40 °C, there was a dramatic jump in its activity, resulting in the nonactivated enzyme having a far greater activity at body temperature than was previously realized. This anomalous change in properties between 30 and 40 °C was observed for multiple functions, and both stimulation (by ADP and phosphorylation) and inhibition (by orthophosphate) were considerably less pronounced at 40 °C than at 30 °C. In general, the allosteric control of PhK's activity is definitely more subtle at body temperature. Changes in behavior related to activity at 40 °C and its control can be explained by the near disappearance of hysteresis at physiological temperature. In important ways, the picture of PhK that has emerged from six decades of study at temperatures of ≤30 °C does not coincide with that of the enzyme studied at physiological temperature. The probable underlying mechanism for the dramatic increase in PhK's activity between 30 and 40 °C is an abrupt change in the conformations of the regulatory β and catalytic γ subunits between these two temperatures.

Acid-base balance and metabolic response of the sea urchin Paracentrotus lividus to different seawater pH and temperatures.

PubMed

Catarino, Ana I; Bauwens, Mathieu; Dubois, Philippe

2012-07-01

In order to better understand if the metabolic responses of echinoids could be related to their acid-base status in an ocean acidification context, we studied the response of an intertidal sea urchin species, Paracentrotus lividus, submitted to low pH at two different temperatures. Individuals were submitted to control (8.0) and low pH (7.7 and 7.4) at 10°C and 16°C (19 days). The relation between the coelomic fluid acid-base status, the RNA/DNA ratio of gonads and the individual oxygen uptake were studied. The coelomic fluid pH decreased with the aquarium seawater, independently of temperature, but this explained only 13% of the pH variation. The coelomic fluid showed though a partial buffer capacity that was not related to skeleton dissolution ([Mg(2+)] and [Ca(2+)] did not differ between pH treatments). There was an interaction between temperature and pH on the oxygen uptake (V (O2)) which was increased at pH 7.7 and 7.4 at 10°C in comparison with controls, but not at 16°C, indicating an upregulation of the metabolism at low temperature and pH. However, gonad RNA/DNA ratios did not differ according to pH and temperature treatments, indicating that even if maintenance of physiological activities has an elevated metabolic cost when individuals are exposed to stress, they are not directly affected during short-term exposure. Long-term studies are needed in order to verify if gonad production/growth will be affected by low pH seawaters exposure.

Continuous measurement of intra-oral pH and temperature: development, validation of an appliance and a pilot study.

PubMed

Choi, J E; Loke, C; Waddell, J N; Lyons, K M; Kieser, J A; Farella, M

2015-08-01

To describe a novel approach for continuous measurement of intra-oral pH and temperature in individuals carrying out normal daily activities over 24 h. We designed, validated and constructed a custom-made appliance fitted with a pH probe and a thermocouple. Six subjects wore the appliance over a 24-h period for two non-consecutive days, while the intra-oral pH and temperature were measured continuously and recorded. Intra-oral pH and temperature were very similar across different recording days, the difference being not statistically significant (P ≥ 0.14). There was a noticeable difference in the pattern of variation of pH between day and night. During the day, the mean pH was 7.3 (±0.4) and dropped markedly only after consumption of acidic food and drinks. The intra-oral pH decreased slowly during sleep with an average pH of 6.6 (±0.4) being recorded. The difference between day and night was statistically significant (P = 0.002). The mean intra-oral temperature was 33.9 °C (±0.9) during daytime and 35·9 °C (±0·5) during sleep (P = 0.013) with minor fluctuations occurring over 24 h. The continuous and simultaneous intra-oral pH and temperature measurement system described in this report is reliable, easy to construct, able to measure variables over a sustained period and may serve as a future diagnostic tool in a number of applications. © 2015 John Wiley & Sons Ltd.

Effective Control of Bioelectricity Generation from a Microbial Fuel Cell by Logical Combinations of pH and Temperature

PubMed Central

Tang, Jiahuan; Liu, Ting; Yuan, Yong

2014-01-01

In this study, a microbial fuel cell (MFC) with switchable power release is designed, which can be logically controlled by combinations of the most physiologically important parameters such as “temperature” and “pH.” Changes in voltage output in response to temperature and pH changes were significant in which voltage output decreased sharply when temperature was lowered from 30°C to 10°C or pH was decreased from 7.0 to 5.0. The switchability of the MFC comes from the microbial anode whose activity is affected by the combined medium temperature and pH. Changes in temperature and pH cause reversible activation-inactivation of the bioanode, thus affecting the activity of the entire MFC. With temperature and pH as input signals, an AND logic operation is constructed for the MFC whose power density is controlled. The developed system has the potential to meet the requirement of power supplies producing electrical power on-demand for self-powered biosensors or biomedical devices. PMID:24741343

Zr/ZrO2 sensors for in situ measurement of pH in high-temperature and -pressure aqueous solutions.

PubMed

Zhang, R H; Zhang, X T; Hu, S M

2008-04-15

The aim of this study is to develop new pH sensors that can be used to test and monitor hydrogen ion activity in hydrothermal conditions. A Zr/ZrO2 oxidation electrode is fabricated for in situ pH measurement of high-temperature aqueous solutions. This sensor responds rapidly and precisely to pH over a wide range of temperature and pressure. The Zr/ZrO2 electrode was made by oxidizing zirconium metal wire with Na2CO3 melt, which produced a thin film of ZrO2 on its surface. Thus, an oxidation-reduction electrode was produced. The Zr/ZrO2 electrode has a good electrochemical stability over a wide range of pH in high-temperature aqueous solutions when used with a Ag/AgCl reference electrode. Measurements of the Zr/ZrO2 sensor potential against a Ag/AgCl reference electrode is shown to vary linearly with pH between temperatures 20 and 200 degrees C. The slope of the potential versus pH at high temperature is slightly below the theoretical value indicated by the Nernst equation; such deviation is attributed to the fact that the sensor is not strictly at equilibrium with the solution to be tested in a short period of time. The Zr/ZrO2 sensor can be calibrated over the conditions that exist in the natural deep-seawater. Our studies showed that the Zr/ZrO2 electrode is a suitable pH sensor for the hydrothermal systems at midocean ridge or other geothermal systems with the high-temperature environment. Yttria-stabilized zirconia sensors have also been used to investigate the pH of hydrothermal fluids in hot springs vents at midocean ridge. These sensors, however, are not sensitive below 200 degrees C. Zr/ZrO2 sensors have wider temperature range and can be severed as good alternative sensors for measuring the pH of hydrothermal fluids.

Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 280 000 years

NASA Astrophysics Data System (ADS)

Ajioka, T.; Yamamoto, M.; Takemura, K.; Hayashida, A.; Kitagawa, H.

2014-10-01

We generated a 280 000 yr record of water pH and temperature in Lake Biwa, central Japan, by analysing the methylation index (MBT') and cyclisation ratio (CBT) of branched tetraethers in sediments from piston and borehole cores. Our aim was to understand the responses of precipitation and air temperature in central Japan to the East Asian monsoon variability on orbital timescales. Because the water pH in Lake Biwa is determined by phosphorus and alkali cation inputs, the record of water pH should indicate the changes in precipitation and temperature in central Japan. Comparison with a pollen assemblage in a Lake Biwa core suggests that lake water pH was determined by summer temperature in the low-eccentricity period before 55 ka, while it was determined by summer precipitation in the high-eccentricity period after 55 ka. From 130 to 55 ka, the variation in lake pH (summer precipitation) lagged behind that in summer temperature by several thousand years. This perspective is consistent with the conclusions of previous studies (Igarashi and Oba, 2006; Yamamoto, 2009), in that the temperature variation preceded the precipitation variation in central Japan.

Arsenic Removal and Its Chemistry in Batch Electrocoagulation Studies.

PubMed

Sharma, Anshul; Adapureddy, Sri Malini; Goel, Sudha

2014-04-01

The aim of this study was to evaluate the impact of different oxidizing agents like light, aeration (by mixing) and electrocoagulation (EC) on the oxidation of As (III) and its subsequent removal in an EC batch reactor. Arsenic solutions prepared using distilled water and groundwater were evaluated. Optimum pH and the effect of varying initial pH on As removal efficiency were also evaluated. MaximumAs (III) removal efficiency with EC, light and aeration was 97% from distilled water and 71% from groundwater. Other results show that EC alone resulted in 90% As removal efficiency in the absence of light and mixing from distilled water and 53.6% from groundwater. Removal with light and mixing but without EC resulted in only 26% As removal from distilled water and 29% from groundwater proving that electro-oxidation and coagulation were more effective in removing arsenic compared to the other oxidizing agents examined. Initial pH was varied from 5 to 10 in distilled water and from 3 to 12 in groundwater for evaluating arsenic removal efficiency by EC. The optimum initial pH for arsenic removal was 7 for distilled water and groundwater. For all initial pHs tested between 5 and 10 in distilled water, the final pH ranged between 7 and 8 indicating that the EC process tends towards near neutral pH under the conditions examined in this study.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guney, Ali; Poyraz, M. Ibrahim; Kangal, Olgac, E-mail: kangal@itu.edu.tr

Highlights: • Both PET and PVC have nearly the same densities. • The best pH value will be 4 for optimizing pH values. • Malic acid gave the best results for selective separation of PET and PVC. - Abstract: Plastics have become the widely used materials because of their advantages, such as cheapness, endurance, lightness, and hygiene. However, they cause waste and soil pollution and they do not easily decompose. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. Depending on their surface characteristics, these plastics can be separated from each othermore » by flotation method which is useful mineral processing technique with its low cost and simplicity. The main objective of this study is to investigate the flotation characteristics of PET and PVC and determine the effect of plasticizer reagents on efficient plastic separation. For that purpose, various parameters such as pH, plasticizer concentration, plasticizer type, conditioning temperature and thermal conditioning were investigated. As a result, PET particles were floated with 95.1% purity and 65.3% efficiency while PVC particles were obtained with 98.1% purity and 65.3% efficiency.« less

Effects of temperature, pH and NaCl on protease activity in digestive tract of young turbot, Scophthalmus maximus

NASA Astrophysics Data System (ADS)

Chen, Muyan; Zhang, Xiumei; Gao, Tianxiang; Chen, Chao

2006-09-01

The protease activity in digestive tract of young turbot Scophthalmus maximum was studied, and the optimal pH, temperature and NaCl concentration were determined for different portions of the fish's internal organs. The optimal activity in the fish's stomach was at pH of 2.2, while that in the intestinal extracts was within the alkaline range from 9.5 to 10.0. In hepatopancreas, the optimal pH was in low alkalinity at 8.5. The optimal reaction temperature was above 40°C in stomach, intestine and hepatopancreas. With increasing temperature, the pH value increased in stomach, while in the intestine, an opposite tendency was observed due to combined effect of pH and temperature. NaCl concentration showed inhibitory impact on protein digestion in hepatopancreas. The main protease for protein digestion in turbot seemed to be pepsin. Moreover, the maximum protease activity in different segments of intestine existed in the hindgut.

Effect of digestion temperature and pH on treatment efficiency and evolution of volatile fatty acids during thermophilic aerobic digestion of model high strength agricultural waste.

PubMed

Ugwuanyi, J Obeta; Harvey, L M; McNeil, B

2005-04-01

Thermophilic aerobic digestion (TAD) of a model agricultural waste, potato peel slurry, at soluble chemical oxygen demand (COD) load equivalent to approximately 8.0 gl(-1), was carried out under batch conditions at 0.5 vvm aeration rate. Digestions were carried out at temperatures of 45, 50, 55, 60 and 65 degrees C (or left unregulated) without pH control to study the effect of digestion temperatures on TAD. The effects of digestion pH on the process were studied at pH 6.0, 7.0, 8.0, 9.0 and 9.5 (and in unregulated control) all at 55 degrees C. Except for digestion at 65 degrees C, which was inoculated extraneously using culture of Bacillus strearothermophilus all reactions were carried out using the populations indigenous to the waste. During digestion at different temperatures, the removal of soluble COD increased with temperature to reach a peak at 60 degrees C before declining slightly, removal of soluble solid (SS) followed similar pattern and reached peak at 65 degrees C being the highest temperature studied, while the degradation of TSS and TS (TSS + TS) decreased with an increase in temperature. Digestion at pH 7.0 was more efficient than at other pH values. Acetate was the predominant volatile fatty acid (VFA) in all the reactions and accounted for up to 90% of the total. Digestion at 60 degrees C led to the greatest accumulation of acetate, and this coincided with the period of highest oxygen uptake, and rapid consumption of soluble carbohydrate. Iso-valerate was also produced at all pH values. Digestion at 55 degrees C and also at pH 7.0 led to rapid and efficient processes with least accumulation of VFA and should be of interest in full-scale processes whenever it is practicable to regulate the digestion pH and temperature. The result of digestion at unregulated pH indicates that gradual adaptation may be used to achieve efficient treatment at elevated pH values. This would be of interest in full-scale processes where it is not practicable to tightly regulate digestion pH, and where the waste is produced at a pH value much higher than neutral.

Additive effects of pCO2 and temperature on respiration rates of the Antarctic pteropod Limacina helicina antarctica.

PubMed

Hoshijima, Umihiko; Wong, Juliet M; Hofmann, Gretchen E

2017-01-01

The Antarctic pteropod, Limacina helicina antarctica , is a dominant member of the zooplankton in the Ross Sea and supports the vast diversity of marine megafauna that designates this region as an internationally protected area. Here, we observed the response of respiration rate to abiotic stressors associated with global change-environmentally relevant temperature treatments (-0.8°C, 4°C) and pH treatments reflecting current-day and future modeled extremes (8.2, 7.95 and 7.7 pH at -0.8°C; 8.11, 7.95 and 7.7 pH at 4°C). Sampling repeatedly over a 14-day period in laboratory experiments and using microplate respirometry techniques, we found that the metabolic rate of juvenile pteropods increased in response to low-pH exposure (pH 7.7) at -0.8°C, a near-ambient temperature. Similarly, metabolic rate increased when pteropods were exposed simultaneously to multiple stressors: lowered pH conditions (pH 7.7) and a high temperature (4°C). Overall, the results showed that p CO 2 and temperature interact additively to affect metabolic rates in pteropods. Furthermore, we found that L. h. antarctica can tolerate acute exposure to temperatures far beyond its maximal habitat temperature. Overall, L. h. antarctica appears to be susceptible to pH and temperature stress, two abiotic stressors which are expected to be especially deleterious for ectothermic marine metazoans in polar seas.

Additive effects of pCO2 and temperature on respiration rates of the Antarctic pteropod Limacina helicina antarctica

PubMed Central

Hoshijima, Umihiko; Wong, Juliet M

2017-01-01

Abstract The Antarctic pteropod, Limacina helicina antarctica, is a dominant member of the zooplankton in the Ross Sea and supports the vast diversity of marine megafauna that designates this region as an internationally protected area. Here, we observed the response of respiration rate to abiotic stressors associated with global change—environmentally relevant temperature treatments (−0.8°C, 4°C) and pH treatments reflecting current-day and future modeled extremes (8.2, 7.95 and 7.7 pH at −0.8°C; 8.11, 7.95 and 7.7 pH at 4°C). Sampling repeatedly over a 14-day period in laboratory experiments and using microplate respirometry techniques, we found that the metabolic rate of juvenile pteropods increased in response to low-pH exposure (pH 7.7) at −0.8°C, a near-ambient temperature. Similarly, metabolic rate increased when pteropods were exposed simultaneously to multiple stressors: lowered pH conditions (pH 7.7) and a high temperature (4°C). Overall, the results showed that pCO2 and temperature interact additively to affect metabolic rates in pteropods. Furthermore, we found that L. h. antarctica can tolerate acute exposure to temperatures far beyond its maximal habitat temperature. Overall, L. h. antarctica appears to be susceptible to pH and temperature stress, two abiotic stressors which are expected to be especially deleterious for ectothermic marine metazoans in polar seas. PMID:29218223

Stability of alemtuzumab solutions at room temperature.

PubMed

Goldspiel, Justin T; Goldspiel, Barry R; Grimes, George J; Yuan, Peng; Potti, Gopal

2013-03-01

The 24-hour stability of alemtuzumab solutions prepared at concentrations not included in the product label and stored in glass or polyolefin containers at room temperature was evaluated. Triplicate solutions of alemtuzumab (6.67, 40, and 120 μg/mL) in 0.9% sodium chloride were prepared in either glass bottles or polyolefin containers and stored at room temperature under normal fluorescent lighting conditions. The solutions were analyzed by a validated stability-indicating high-performance liquid chromatography (HPLC) assay at time zero and 8, 14, and 24 hours after preparation; solution pH values were measured and the containers visually inspected at all time points. Stability was defined as the retention of ≥90% of the initial alemtuzumab concentration. HPLC analysis indicated that the percentage of the initial alemtuzumab concentration retained was >90% for all solutions evaluated, with no significant changes over the study period. The most dilute alemtuzumab solution (6.67 μg/mL) showed some degradation (91% of the initial concentration retained at hour 24), whereas the retained concentration was >99% for all other preparations throughout the study period. Solution pH values varied by drug concentration but did not change significantly over 24 hours. No evidence of particle formation was detected in any solution by visual inspection at any time during the study. Solutions of alemtuzumab 6.67 μg/mL stored in glass bottles and solutions of 40 and 120 μg/mL stored in polyolefin containers were stable for at least 24 hours at room temperature.

Few Like it Hot: Coral Reef Reponses to Elevated Temperatures and CO2

NASA Astrophysics Data System (ADS)

Eakin, C. M.; Gledhill, D. K.; Heron, S. F.; Skirving, W.; Christensen, T.; Morgan, J.; Liu, G.; Strong, A. E.

2007-12-01

Coral reefs live within a fairly narrow envelope of environmental conditions constrained by water temperatures, light, salinity, nutrients, bathymetry and the aragonite saturation state of seawater. As documented in numerous studies, the world's coral reefs are "in crisis" as a result of human impacts on their environment. While local stresses currently dominate, coral reefs are increasingly confronted with global-scale changes due to rising greenhouse gas concentrations. These changes are rapidly modifying the environmental envelope of coral reefs through both increased thermal stress and ocean acidification. In the former case, there is a well-documented relationship between thermal stress and the response of corals that include coral bleaching, disease, and mortality. Clear tolerance thresholds exist beyond which high temperature and accumulated thermal stress have deleterious effects. However, the synergistic effects of increasing temperature and ocean acidification are not yet fully understood. At this time, there is mounting concern that decreasing pH and aragonite saturation state will cause net reef accretion to cease or become negative. The threshold at which this could occur is likely to be reached much sooner than the pH drop necessary to induce carbonate dissolution. Both the thermal and chemical limits that control coral survival and reef growth will likely be passed before 2100 assuming even conservative projections reported in the 4th Assessment Report of the Intergovernmental Panel on Climate Change. This talk will discuss these thresholds and their ramifications for ecosystems and resource management.

Pharmaceutical Perspective on Opalescence and Liquid-Liquid Phase Separation in Protein Solutions.

PubMed

Raut, Ashlesha S; Kalonia, Devendra S

2016-05-02

Opalescence in protein solutions reduces aesthetic appeal of a formulation and can be an indicator of the presence of aggregates or precursor to phase separation in solution signifying reduced product stability. Liquid-liquid phase separation of a protein solution into a protein-rich and a protein-poor phase has been well-documented for globular proteins and recently observed for monoclonal antibody solutions, resulting in physical instability of the formulation. The present review discusses opalescence and liquid-liquid phase separation (LLPS) for therapeutic protein formulations. A brief discussion on theoretical concepts based on thermodynamics, kinetics, and light scattering is presented. This review also discusses theoretical concepts behind intense light scattering in the vicinity of the critical point termed as "critical opalescence". Both opalescence and LLPS are affected by the formulation factors including pH, ionic strength, protein concentration, temperature, and excipients. Literature reports for the effect of these formulation factors on attractive protein-protein interactions in solution as assessed by the second virial coefficient (B2) and the cloud-point temperature (Tcloud) measurements are also presented. The review also highlights pharmaceutical implications of LLPS in protein solutions.

Wheat production in controlled environments

NASA Technical Reports Server (NTRS)

Salisbury, Frank B.; Bugbee, Bruce; Bubenheim, David

1987-01-01

Conditions are optimized for maximum yield and quality of wheat to be used in a controlled environment life support system (CELSS) in a Lunar or Martian base or a spacecraft. With yields of 23 to 57 g/sq m/d of edible biomass, a minimum size for a CELSS would be between 12 and 30 sq m per person, utilizing about 600 W/sq m of electrical energy for artificial light. Temperature, irradiance, photoperiod, carbon dioxide levels, humidity, and wind velocity are controlled in growth chambers. Nutrient solutions (adjusted for wheat) are supplied to the roots via a recirculating system that controls pH by adding HNO3 and controlling the NO3/NH4 ratio in solution. A rock-wool plant support allows direct seeding and densities up to 10,000 plants sq m. Densities up to 2000 plants/sq m appear to increase seed yield. Biomass production increases almost linearily with increasing irradiance from 400 to 1700 micromol/sq m/s of photosynthetic photon flux, but the efficiency of light utilization decreases over this range. Photoperiod and temperature both have a profound influence on floral initiation, spikelet formation, stem elongation, and fertilization.

Results and evaluation of a pilot primary monitoring network, San Francisco Bay, California, 1978

USGS Publications Warehouse

Bradford, W.L.; Iwatsubo, R.T.

1980-01-01

A primary monitoring network of 12 stations, with measurements at 1-meter depth intervals every 2 weeks during periods of high inflow from the Sacramento-San Joaquin River delta, and every 4-6 weeks during seasonal low delta inflows, appears adequate to observe major changes in ambient water quality in San Francisco Bay. A 1-year study tested the network operation and determined that analysis of the data could demonstrate the major changes in salinity, temperature, and light-attenuation distributions known to occur, based on earlier research, in response to variations of delta inflow and to other physical processes. Observations of eddies at two stations, of the influence of water from a river flooding in the extreme south bay, and of difference in salinity and temperature laterally across the entrance to the south bay are all new but are consistent with existing models. The pH, dissolved oxygen, and light-attenuation measurements, while adequate to observe small-scale vertical variations, are not sufficiently sensitive to detect the effects of phytoplankton blooms. (USGS)

An organic self-regulating microfluidic system.

PubMed

Eddington, D T; Liu, R H; Moore, J S; Beebe, D J

2001-12-01

In this paper we present an organic feedback scheme that merges microfluidics and responsive materials to address several limitations of current microfluidic systems. By using in situ fabrication and by taking advantage of microscale phenomena (e.g., laminar flow, short diffusion times), we have demonstrated feedback control of the output pH in a completely organic system. The system autonomously regulates an output stream at pH 7 under a range of input flow conditions. A single responsive hydrogel component performs the functionality of traditional feedback system components. Vertically stacked laminar flow is used to improve the time response of the hydrogel actuator. A star shaped orifice is utilized to improve the flow characteristics of the membrane/orifice valve. By changing the chemistry of the hydrogel component, the system can be altered to regulate flow based on hydrogels sensitive to temperature, light, biological/molecular, and others.

Photocatalytic degradation of organic dyes using composite nanofibers under UV irradiation

NASA Astrophysics Data System (ADS)

Salama, Ahmed; Mohamed, Alaa; Aboamera, Nada M.; Osman, T. A.; Khattab, A.

2018-02-01

In this work, photocatalytic degradation of organic dyes such as methylene blue (MB) and indigo carmine (IC) have been studied by composite nanofibers systems containing cellulose acetate (CA), multiwall carbon nanotubes (CNT) and TiO2 nanoparticles under UV light. The amino factionalized TiO2-NH2 NPs cross-linked to the CA/CNT composite nanofibers works as a semiconductor catalyst. The morphology and crystallinity were characterized by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and Fourier transform infrared spectroscopy. It was also seen that many factors affected the photodegradation rate, mainly the pH of the solution and the dye concentration, temperature, etc. The study demonstrated that IC degrades at a higher rate than MB. The maximum photodegradation rate of both organic dyes was achieved at a pH 2. In comparison to other studies, this work achieved high photodegradation rate in lower time and using less power intensity.

Enhancing the luminescence of Eu3+ /Eu2+ ion-doped hydroxyapatite by fluoridation and thermal annealing.

PubMed

Van, Hoang Nhu; Tam, Phuong Dinh; Kien, Nguyen Duc Trung; Huy, Pham Thanh; Pham, Vuong-Hung

2017-08-01

This paper reports a novel way for the synthesis of a europium (Eu)-doped fluor-hydroxyapatite (FHA) nanostructure to control the luminescence of hydroxyapatite nanophosphor, particularly, by applying optimum fluorine concentrations, annealed temperatures and pH value. The Eu-doped FHA was made using the co-precipitation method followed by thermal annealing in air and reducing in a H 2 atmosphere to control the visible light emission center of the nanophosphors. The intensities of the OH - group decreased with the increasing fluorine concentrations. For the specimens annealed in air, the light emission center of the nanophosphor was 615 nm, which was emission from the Eu 3 + ion. However, when they were annealed in reduced gas (Ar + 5% H 2 ), a 448 nm light emission center from the Eu 2 + ion of FHA was observed. The presence of fluorine in Eu-doped FHA resulted in a significant enhancement of nanophosphor luminescence, which has potential application in light emission and nanomedicine. Copyright © 2016 John Wiley & Sons, Ltd.

Stability of Tranexamic Acid after 12-Week Storage at Temperatures from -20 deg C to 50 deg C

DTIC Science & Technology

2013-07-01

PRELIMINARY REPORTS STABILITY OF TRANEXAMIC ACID AFTER 12-WEEK STORAGE AT TEMPERATURES FROM –20◦C TO 50◦C Rodolfo de Guzman, Jr., MT, I. Amy...Polykratis, BS, Jill L. Sondeen, PhD, Daniel N. Darlington, PhD, Andrew P. Cap, MD, PhD, Michael A. Dubick, PhD ABSTRACT Background. Tranexamic acid (TXA) is... tranexamic acid ; temperature stability; HPLC; thromboelastography; storage PREHOSPITAL EMERGENCY CARE 2013;17:394–400 BACKGROUND Hemorrhage is the leading

Separation of abscission zone cells in detached Azolla roots depends on apoplastic pH.

PubMed

Fukuda, Kazuma; Yamada, Yoshiya; Miyamoto, Kensuke; Ueda, Junichi; Uheda, Eiji

2013-01-01

In studies on the mechanism of cell separation during abscission, little attention has been paid to the apoplastic environment. We found that the apoplastic pH surrounding abscission zone cells in detached roots of the water fern Azolla plays a major role in cell separation. Abscission zone cells of detached Azolla roots were separated rapidly in a buffer at neutral pH and slowly in a buffer at pH below 4.0. However, cell separation rarely occurred at pH 5.0-5.5. Light and electron microscopy revealed that cell separation was caused by a degradation of the middle lamella between abscission zone cells at both pH values, neutral and below 4.0. Low temperature and papain treatment inhibited cell separation. Enzyme(s) in the cell wall of the abscission zone cells might be involved in the degradation of the pectin of the middle lamella and the resultant, pH-dependent cell separation. By contrast, in Phaseolus leaf petioles, unlike Azolla roots, cell separation was slow and increased only at acidic pH. The rapid cell separation, as observed in Azolla roots at neutral pH, did not occur. Indirect immunofluorescence microscopy, using anti-pectin monoclonal antibodies, revealed that the cell wall pectins of the abscission zone cells of Azolla roots and Phaseolus leaf petioles looked similar and changed similarly during cell separation. Thus, the pH-related differences in cell separation mechanisms of Azolla and Phaseolus might not be due to differences in cell wall pectin, but to differences in cell wall-located enzymatic activities responsible for the degradation of pectic substances. A possible enzyme system is discussed. Copyright © 2012 Elsevier GmbH. All rights reserved.

Development of luminescent pH sensor films for monitoring bacterial growth through tissue.

PubMed

Wang, Fenglin; Raval, Yash; Chen, Hongyu; Tzeng, Tzuen-Rong J; DesJardins, John D; Anker, Jeffrey N

2014-02-01

Although implanted medical devices (IMDs) offer many benefits, they are susceptible to bacterial colonization and infections. Such infections are difficult to treat because bacteria could form biofilms on the implant surface, which reduce antibiotics penetration and generate local dormant regions with low pH and low oxygen. In addition, these infections are hard to detect early because biofilms are often localized on the surface. Herein, an optical sensor film is developed to detect local acidosis on an implanted surface. The film contains both upconverting particles (UCPs) that serve as a light source and a pH indicator that alters the luminescence spectrum. When irradiated with 980 nm light, the UCPs produce deeply penetrating red light emission, while generating negligible autofluorescence in the tissue. The basic form of the pH indicator absorbs more of upconversion luminescence at 661 nm than at 671 nm and consequently the spectral ratio indicates pH. Implanting this pH sensor film beneath 6-7 mm of porcine tissue does not substantially affect the calibration curve because the peaks are closely spaced. Furthermore, growth of Staphylococcus epidermidis on the sensor surface causes a local pH decrease that can be detected non-invasively through the tissue. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature-Induced Remodeling of the Photosynthetic Machinery Tunes Photosynthesis in the Thermophilic Alga Cyanidioschyzon merolae1

PubMed Central

Nikolova, Denitsa; Weber, Dieter; Scholz, Martin

2017-01-01

The thermophilic alga C. merolae thrives in extreme environments (low pH and temperature between 40°C and 56°C). In this study, we investigated the acclimation process of the alga to a colder temperature (25°C). A long-term cell growth experiment revealed an extensive remodeling of the photosynthetic apparatus in the first 250 h of acclimation, which was followed by cell growth to an even higher density than the control (grown at 42°C) cell density. Once the cells were shifted to the lower temperature, the proteins of the light-harvesting antenna were greatly down-regulated and the phycobilisome composition was altered. The amount of PSI and PSII subunits was also decreased, but the chlorophyll to photosystems ratio remained unchanged. The 25°C cells possessed a less efficient photon-to-oxygen conversion rate and require a 2.5 times higher light intensity to reach maximum photosynthetic efficiency. With respect to chlorophyll, however, the photosynthetic oxygen evolution rate of the 25°C culture was 2 times higher than the control. Quantitative proteomics revealed that acclimation requires, besides remodeling of the photosynthetic apparatus, also adjustment of the machinery for protein folding, degradation, and homeostasis. In summary, these remodeling processes tuned photosynthesis according to the demands placed on the system and revealed the capability of C. merolae to grow under a broad range of temperatures. PMID:28270628

Response surface methodology as an approach to determine optimal activities of lipase entrapped in sol-gel matrix using different vegetable oils.

PubMed

Pinheiro, Rubiane C; Soares, Cleide M F; de Castro, Heizir F; Moraes, Flavio F; Zanin, Gisella M

2008-03-01

The conditions for maximization of the enzymatic activity of lipase entrapped in sol-gel matrix were determined for different vegetable oils using an experimental design. The effects of pH, temperature, and biocatalyst loading on lipase activity were verified using a central composite experimental design leading to a set of 13 assays and the surface response analysis. For canola oil and entrapped lipase, statistical analyses showed significant effects for pH and temperature and also the interactions between pH and temperature and temperature and biocatalyst loading. For the olive oil and entrapped lipase, it was verified that the pH was the only variable statistically significant. This study demonstrated that response surface analysis is a methodology appropriate for the maximization of the percentage of hydrolysis, as a function of pH, temperature, and lipase loading.

The O2, pH and Ca2+ Microenvironment of Benthic Foraminifera in a High CO2 World

PubMed Central

Glas, Martin S.; Fabricius, Katharina E.; de Beer, Dirk; Uthicke, Sven

2012-01-01

Ocean acidification (OA) can have adverse effects on marine calcifiers. Yet, phototrophic marine calcifiers elevate their external oxygen and pH microenvironment in daylight, through the uptake of dissolved inorganic carbon (DIC) by photosynthesis. We studied to which extent pH elevation within their microenvironments in daylight can counteract ambient seawater pH reductions, i.e. OA conditions. We measured the O2 and pH microenvironment of four photosymbiotic and two symbiont-free benthic tropical foraminiferal species at three different OA treatments (∼432, 1141 and 2151 µatm pCO2). The O2 concentration difference between the seawater and the test surface (ΔO2) was taken as a measure for the photosynthetic rate. Our results showed that O2 and pH levels were significantly higher on photosymbiotic foraminiferal surfaces in light than in dark conditions, and than on surfaces of symbiont-free foraminifera. Rates of photosynthesis at saturated light conditions did not change significantly between OA treatments (except in individuals that exhibited symbiont loss, i.e. bleaching, at elevated pCO2). The pH at the cell surface decreased during incubations at elevated pCO2, also during light incubations. Photosynthesis increased the surface pH but this increase was insufficient to compensate for ambient seawater pH decreases. We thus conclude that photosynthesis does only partly protect symbiont bearing foraminifera against OA. PMID:23166810

Immunomodulatory effects of temperature and pH of water in an Indian freshwater sponge.

PubMed

Mukherjee, Soumalya; Bhunia, Anindya Sundar; Bhunia, Niladri Sekhar; Ray, Mitali; Ray, Sajal

2016-07-01

Eunapius carteri, a freshwater sponge of India, inhabits the ponds and lakes and experiences variations of temperature and pH of water throughout the year. Sponges bear evolutionary and ecological importance with limited information on their immunological attribute and adaptational resilience in a changing environment. This paper reports temperature and pH specific responses of immune related parameters in sponge maintained in the experimental conditions of laboratory. Innate immunological parameters like phagocytosis and generation of cytotoxic molecules like superoxide anion, nitric oxide and phenoloxidase activity were estimated in E. carteri at different environmentally realistic water temperatures (10, 20, 30 and 40°C) and pH (6.4, 7.4 and 8.4). Phagocytosis and cytotoxicity are established as important immune parameters of invertebrates. Calalase, an antioxidant enzyme and phosphatases are involved in pathogen destruction and are considered as components of innate immunity. Activities of catalase, acid and alkaline phosphatases were estimated in E. carteri at different thermal regimes and pH. Modulation of phagocytic and cytotoxic responses and the activities of catalase and phosphatases at different water temperatures and pH indicated temperature and pH specific immunological status of E. carteri. Present investigation deals with the effects of selected hydrological parameters on the fundamental immune related parameters in sponge indicating its adaptational plasticity. Immunological resilience of this species in the face of variation of water temperature and pH is thought to be a special adaptive feature of sponge, a reported "living fossil". Copyright © 2016 Elsevier Ltd. All rights reserved.

INACTIVATION AND REACTIVATION OF B. MEGATHERIUM PHAGE

PubMed Central

Northrop, John H.

1955-01-01

Preparation of Reversibly Inactivated (R.I.) Phage.— If B. megatherium phage (of any type, or in any stage of purification) is suspended in dilute salt solutions at pH 5–6, it is completely inactivated; i.e., it does not form plaques, or give rise to more phage when mixed with a sensitive organism (Northrop, 1954). The inactivation occurs when the phage is added to the dilute salt solution. If a suspension of the inactive phage in pH 7 peptone is titrated to pH 5 and allowed to stand, the activity gradually returns. The inactivation is therefore reversible. Properties of R.I. Phage.— The R.I. phage is adsorbed by sensitive cells at about the same rate as the active phage. It kills the cells, but no active phage is produced. The R.I. phage therefore has the properties of phage "ghosts" (Herriott, 1951) or of colicines (Gratia, 1925), or phage inactivated by ultraviolet light (Luria, 1947). The R.I. phage is sedimented in the centrifuge at the same rate as active phage. It is therefore about the same size as the active phage. The R.I. phage is most stable in pH 7, 5 per cent peptone, and may be kept in this solution for weeks at 0°C. The rate of digestion of R.I. phage by trypsin, chymotrypsin, or desoxyribonuclease is about the same as that of active phage (Northrop, 1955 a). Effect of Various Substances on the Formation of R.I. Phage.— There is an equilibrium between R.I. phage and active phage. The R.I. form is the stable one in dilute salt solution, pH 5 to 6.5 and at low temperature (<20°C.). At pH >6.5, in dilute salt solution, the R.I. phage changes to the active form. The cycle, active ⇌ inactive phage, may be repeated many times at 0°C. by changing the pH of the solution back and forth between pH 7 and pH 6. Irreversible inactivation is caused by distilled water, some heavy metals, concentrated urea or quanidine solutions, and by l-arginine. Reversible inactivation is prevented by all salts tested (except those causing irreversible inactivation, above). The concentration required to prevent R.I. is lower, the higher the valency of either the anion or cation. There are great differences, however, between salts of the same valency, so that the chemical nature as well as the valency is important. Peptone, urea, and the amino acids, tryptophan, leucine, isoleucine, methionine, asparagine, dl-cystine, valine, and phenylalanine, stabilize the system at pH 7, so that no change occurs if a mixture of R.I. and active phage is added to such solutions. The active phage remains active and the R.I. phage remains inactive. The R.I. phage in pH 7 peptone becomes active if the pH is changed to 5.0. This does not occur in solutions of urea or the amino acids which stabilize at pH 7.0. Kinetics of Reversible Inactivation.— The inactivation is too rapid, even at 0° to allow the determination of an accurate time-inactivation curve. The rate is independent of the phage concentration and is complete in a few seconds, even in very dilute suspensions containing <1 x 104 particles/ml. This result rules out any type of bimolecular reaction, or any precipitation or agglutination mechanism, since the minimum theoretical time for precipitation (or agglutination) of a suspension of particles in a concentration of only 1 x 104 per ml. would be about 300 days even though every collision were effective. Mechanism of Salt Reactivation.— Addition of varying concentrations of MgSO4 (or many other salts) to a suspension of either active or R.I. phage in 0.01 M, pH 6 acetate buffer results in the establishment of an equilibrium ratio for active/R.I. phage. The higher the concentration of salt, the larger proportion of the phage is active. The results, with MgSO4, are in quantitative agreement with the following reaction: See PDF for Equation Effect of Temperature.— The rate of inactivation is too rapid to be measured with any accuracy, even at 0°C. The rate of reactivation in pH 5 peptone, at 0 and 10°, was measured and found to have a temperature coefficient Q 10 = 1.5 corresponding to a value of E (Arrhenius' constant) of 6500 cal. mole–1. This agrees very well with the temperature coefficient for the reactivation of denatured soy bean trypsin inhibitor (Kunitz, 1948). The equilibrium between R.I. and active phage is shifted toward the active side by lowering the temperature. The ratio R.I.P./AP is 4.7 at 15° and 2.8 at 2°. This corresponds to a change in free energy of –600 cal. mole–1 and a heat of reaction of 11,000. These values are much lower than the comparative one for trypsin (Anson and Mirsky, 1934 a) or soy bean trypsin inhibitor (Kunitz, 1948). Neither the inactivation nor the reactivation reactions are affected by light. The results in general indicate that there is an equilibrium between active and R.I. phage. The R.I. phage is probably an intermediate step in the formation of inactive phage. The equilibrium is shifted to the active side by lowering the temperature, adjusting the pH to 7–8 (except in the presence of high concentrations of peptone), raising the salt concentration, or increasing the valency of the ions present. The reaction may be represented by the following: See PDF for Equation The assumption that the active/R.I. phage equilibrium represents an example of native/denatured protein equilibrium predicts all the results qualitatively. Quantitatively, however, it fails to predict the relative rate of digestion of the two forms by trypsin or chymotrypsin, and also the effect of temperature on the equilibrium. PMID:13271723

Stability of Levothyroxine in Sodium Chloride for IV Administration.

PubMed

Strong, Dawn K; Decarie, Diane; Ensom, Mary H H

2010-11-01

Levothyroxine by IV administration is often prescribed in the intensive care unit for the management of potential solid organ donors, following declaration of brain death and provision of consent for organ donation. Published data on the stability of levothyroxine in IV solutions are limited. To evaluate the physical compatibility and chemical stability, over a 24-h period, of 2 concentrations of levothyroxine in 0.9% sodium chloride with storage at room temperature and with exposure to or protection from light. Levothyroxine solutions (0.4 μg/mL and 2.0 μg/mL) were prepared in 50-mL minibags of 0.9% NaCl and stored at room temperature (25°C) with exposure to or protection from light. Samples were collected from each minibag at time 0 and after 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 8.0, 12.0, and 24.0 h. The samples were analyzed in triplicate with a validated stability-indicating high-performance liquid chromatography method using ultraviolet detection. A solution was considered stable if it maintained 90% of its initial concentration of levothyroxine. Changes in colour, clarity, and pH were assessed to determine the physical compatibility of the solutions. All samples remained clear, colourless, and free of precipitate throughout the study, and there were no significant changes in pH. Based on the 95% confidence interval of the slope of the curve relating concentration to time determined by linear regression, solutions of levothyroxine with concentration 0.4 μg/mL would maintain at least 90% of the initial concentration for 16.9 h with exposure to light and for 18.0 h if kept in the dark. Solutions of levothyroxine with concentration 2.0 μg/mL would maintain at least 90% of the initial concentration for 6.5 h with exposure to light and for 12.0 h if kept in the dark, with 95% confidence. Extemporaneously prepared solutions of levothyroxine in 0.9% NaCl can be expected to remain stable for at least 6.5 h if stored without protection from light and at least 12 h if stored in the dark. Stability is related to concentration, with more dilute solutions having greater stability.

Milk pH as a function of CO2 concentration, temperature, and pressure in a heat exchanger.

PubMed

Ma, Y; Barbano, D M

2003-12-01

Raw skim milk, with or without added CO2, was heated, held, and cooled in a small pilot-scale tubular heat exchanger (372 ml/min). The experiment was replicated twice, and, for each replication, milk was first carbonated at 0 to 1 degree C to contain 0 (control), 600, 1200, 1800, and 2400 ppm added CO2 using a continuous carbonation unit. After storage at 0 to 1 degree C, portions of milk at each CO2 concentration were heated to 40, 56, 72, and 80 degrees C, held at the desired temperature for 30 s (except 80 degrees C, holding 20 s) and cooled to 0 to 1 degree C. At each temperature, five pressures were applied: 69, 138, 207, 276, and 345 kPa. Pressure was controlled with a needle valve at the heat exchanger exit. Both the pressure gauge and pH probe were inline at the end of the holding section. Milk pH during heating depended on CO2 concentration, temperature, and pressure. During heating of milk without added CO2, pH decreased linearly as a function of increasing temperature but was independent of pressure. In general, the pH of milk with added CO2 decreased with increasing CO2 concentration and pressure. For milk with added CO2, at a fixed CO2 concentration, the effect of pressure on pH decrease was greater at a higher temperature. At a fixed temperature, the effect of pressure on pH decrease was greater for milk with a higher CO2 concentration. Thermal death of bacteria during pasteurization of milk without added CO2 is probably due not only to temperature but also to the decrease in pH that occurs during the process. Increasing milk CO2 concentration and pressure decreases the milk pH even further during heating and may further enhance the microbial killing power of pasteurization.

Evaluation of Eurasian Watermilfoil Control Techniques Using Aquatic Herbicides in Fort Peck Lake, Montana

DTIC Science & Technology

2015-07-01

19 Table 3. Temperature , dissolved oxygen , pH, and wind...21 Table 4. Temperature , dissolved oxygen , and pH measured in the study plots following treatment, Fort Peck Lake, MT, 2012...quality, particularly temperature , pH, dissolved oxygen , and nutrient cycling (Prentki et al. 1979; Carpenter and Lodge 1986, Frodge et al. 1990; Boylen

Stability of Alprostadil in 0.9% Sodium Chloride Stored in Polyvinyl Chloride Containers.

PubMed

McCluskey, Susan V; Kirkham, Kylian; Munson, Jessica M

2017-01-01

The stability of alprostadil diluted in 0.9% sodium chloride stored in polyvinyl chloride (VIAFLEX) containers at refrigerated temperature, protected from light, is reported. Five solutions of alprostadil 11 mcg/mL were prepared in 250 mL 0.9% sodium chloride polyvinyl chloride (PL146) containers. The final concentration of alcohol was 2%. Samples were stored under refrigeration (2°C to 8°C) with protection from light. Two containers were submitted for potency testing and analyzed in duplicate with the stability-indicating high-performance liquid chromatography assay at specific time points over 14 days. Three containers were submitted for pH and visual testing at specific time points over 14 days. Stability was defined as retention of 90% to 110% of initial alprostadil concentration, with maintenance of the original clear, colorless, and visually particulate-free solution. Study results reported retention of 90% to 110% initial alprostadil concentration at all time points through day 10. One sample exceeded 110% potency at day 14. pH values did not change appreciably over the 14 days. There were no color changes or particle formation detected in the solutions over the study period. This study concluded that during refrigerated, light-protected storage in polyvinyl chloride (VIAFLEX) containers, a commercial alcohol-containing alprostadil formulation diluted to 11 mcg/mL with 0.9% sodium chloride 250 mL was stable for 10 days. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Low-temperature synthesis and investigations on photocatalytic activity of nanoparticles BiFeO3 for methylene blue and methylene orange degradation and some toxic organic compounds

NASA Astrophysics Data System (ADS)

Nhiem Dao, Ngoc; Luu, Minh Dai; Chuc Pham, Ngoc; Dung Doan, Trung; Nguyen, Thi Ha Chi; Bac Nguyen, Quang; Lim Duong, Thi

2016-12-01

The photocatalytic BiFeO3 perovskite nanoparticles were fabricated by gel combustion method using polyvinyl alcohol and corresponding metal nitrate precursors under the optimum mild conditions such as pH 2, gel formation temperature of 80 °C, metal/polyvinyl alcohol molar ratio of 1/3, metal molar ratio Bi/Fe of 1/1 and calcination temperature at 500 °C for 2 h. The prepared sample was characterized by x-ray diffraction, field scanning electron microscopy, transmission electron microscopy, Brunauer-Emmetl-Teller nitrogen adsorption method at 77 K, energy dispersive x-ray spectroscopy, ultraviolet-visible light spectrophotometry, and thermal analysis. The effects of molar ratios of starting material and calcination temperature on phase formation and morphology were investigated. The degradation of methylene blue, methylene orange and some toxic organic compounds such as phenol and diazinon under visible light irradiation by photocatalytic BiFeO3 nanoparticles were evaluated at different parameters and conditions such as the light intensity determined from the light source to the measured sample, the addition H2O2, reaction time and the regeneration performance. Obtained results showed that the synthesized perovskite BiFeO3 nanoparticles for the optimized sample have a size smaller than 50 nm and the high mean surface area of 50 m2 g-1. Degradation efficiency was almost 90.0% for methylene blue and 80.0% for methylene orange with added H2O2 after 30 min of reaction. After the 3rd time of regeneration, the BiFeO3 nanoparticles still have 92.8% of the degradation performance for removing methylene blue. Phenol and diazinon toxic compound were degraded with the performance of 92.42% and 85.7%, respectively, for 150 min

Effects of experimental long-term CO2 exposure on Daphnia magna (Straus 1820): From physiological effects to ecological consequences.

PubMed

Parra, Gema; Galotti, Andréa; Jiménez-Melero, Raquel; Guerrero, Francisco; Sánchez-Moyano, Emilio; Jiménez-Gómez, Francisco; Conradi, Mercedes

2016-08-01

The carbon capture and storage (CCS) technologies that were proposed to mitigate environmental problems arising from anthropogenic CO2 emissions, also have potential environmental risks. An eventual CCS leak might induce very low pH values in the aquatic system. Due to the lack of knowledge of long-term CO2 exposures with very low pH values, this study aims to know the effects and consequences of such a situation for zooplankton, using the Daphnia magna experimental model. A CO2 injection system was used to provide the experimental condition. A twenty-one days experiment with control and low pH treatment (pH = 7) replicates was carried out under light and temperature-controlled conditions. Survival, individual growth, RNA:DNA ratio, and neonates production were analysed during the aforementioned period. No differences on survival (except last day), individual growth and RNA:DNA ratio were observed between both control and low pH treatments. However, clear differences were detected in neonates production and, consequently, in population growth rates and secondary production. The observed differences could be related with an energy allocation strategy to ensure individual survival but would have ecological consequences affecting higher trophic levels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Persistence of spiromesifen in soil: influence of moisture, light, pH and organic amendment.

PubMed

Mate, Ch Jamkhokai; Mukherjee, Irani; Das, Shaon Kumar

2015-02-01

Persistence of spiromesifen in soil as affected by varying moisture, light, compost amendment, soil sterilization and pH in aqueous medium were studied. Degradation of spiromesifen in soil followed the first-order reaction kinetics. Effect of different moisture regimes indicated that spiromesifen dissipated faster in submerged soil (t 1/2 14.3-16.7 days) followed by field capacity (t 1/2 18.7-20.0 days), and dry soil (t 1/2 21.9-22.9 days). Dissipation was faster in sterilized submerged (t 1/2 17.7 days) than in sterilized dry (t 1/2 35.8 days). Photo spiromesifen metabolite was not detected under different moisture regimes. After 30 days, enol spiromesifen metabolite was detected under submerged condition and was below detectable limit (<0.001 μg g(-1)) after 90 days. Soil amendment compost (2.5 %) at field capacity enhanced dissipation of the insecticide, and half-life value was 14.3 against 22.4 days without compost amendment. Under different pH condition, residues persisted in water with half-life values 5.7 to 12.5 days. Dissipation in water was faster at pH 9.0 (t 1/2 5.7 days), followed by pH 4.0 (t 1/2 9.7 days) and pH 7.2 (t 1/2 12.5 days). Exposure of spiromesifen to different light conditions indicated that it was more prone to degradation under UV light (t 1/2 3-4 days) than sunlight exposure (t 1/2 5.2-8.1 days). Under sunlight exposure, photo spiromesifen metabolite was detected after 10 and 15 days as compared to 3 and 5 days under UV light exposure.

Study on Photocatalytic Properties of TiO2 Nanoparticle in various pH condition

NASA Astrophysics Data System (ADS)

Nasikhudin; Diantoro, M.; Kusumaatmaja, A.; Triyana, K.

2018-04-01

Titanium dioxide has been widely studied for its ability to photocatalytic and applications have high performance for photovoltaic applications. In this paper TiO2 nanoparticle was investigated for the degradation of methylene blue under UV light in various pH condition. The TiO2 nanoparticle was characterized by SEM and XRD. The results showed that TiO2 nanoparticle has the structure of anatase and have a particle size of 27 nm. The photocatalytic activity of TiO2 nanoparticle show that the degradation of methylene blue under UV light have dye removal of 97% dye was degraded in 3 h, but the degradation of methylene blue without UV light have dye removal of 15% dye was degraded in 3 h. It indicated that The photocatalytic activity of TiO2 nanoparticle could occur if there the UV light. If not UV light the photocatalytic activity cannot occurs, the degradation of Methylene Blue 15% is not a photocatalytic activity but it is adsorption of Methylene Blue by TiO2 nanoparticle. The photocatalytic activity of TiO2 nanoparticle has pH-sensitive. The photocatalytic activity of TiO2 nanoparticle in acid condition (pH 4.1) is 40%, in neutral condition (pH 7.0) is 90%, and in base condition (pH 9.7) is 97%. The highest photocatalytic activity occurs in base condition, it causes in base condition OH- can be direct reaction with a hole to produce hydroxyl radical (OH*).

Effect of pH and temperature upon self-assembling process between poly(aspartic acid) and Pluronic F127.

PubMed

Nita, Loredana E; Chiriac, Aurica P; Bercea, Maria

2014-07-01

The present investigation was made in order to evaluate the capability of self-assembling of the two water soluble polymers, respectively, poly(aspartic acid) and Pluronic F127 into well interpenetrated mixture, and to evidence the connection effects intervened during polymer complex formation to exhibit good stability once formed, as well to understand and correlate the binding strength and the interval between better association domains. The effect of pH and temperature on the interpolymeric complex formation between poly(aspartic acid) and Pluronic F127 was studied by combining rheology with light scattering technique. The solution mixtures between poly(aspartic acid) and Pluronic F127 are Newtonian fluids for all ratios among them. Depending on the polymeric mixture composition and experimental temperature, positive or negative deviations of the experimental values from the additive dependence appear. An interesting behavior was registered around 1/1 wt. ratio between the two polymers, when the hydrodynamic diameter of the interpenetrated polymeric particles decreased suddenly. This allows us to conclude the formation of core-shell micelle structure with poly(aspartic acid) core and Pluronic F127 as shell, performed through strong interactions between polymers. This behavior was sustained by the increase of absolute value of zeta potential owing to the decrease of functional groups number at the surface of micelles. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, Structure, White-Light Emission, and Temperature Recognition Properties of Eu/Tb Mixed Coordination Polymers.

PubMed

An, Ran; Zhao, Hui; Hu, Huai-Ming; Wang, Xiaofang; Yang, Meng-Lin; Xue, Ganglin

2016-01-19

Two series of Eu(III)/Tb(III) coordination polymers, [LnL(glu)]n·2nH2O (Ln = Eu (1), Tb (2)) and [LnL(glu)(H2O)]n (Ln = Eu (3), Tb (4)) [HL = (2-(2-sulfophenyl)imidazo(4,5-f)(1,10)-phenanthroline, H2glu = glutaric acid] have been hydrothermally synthesized by controlling the pH values and characterized by elemental analysis, infrared spectra, and single-crystal X-ray diffraction. Isomorphic compounds 1 and 2 exhibit 6-connected 3D network with the pcu topological net, containing left- and right-handed helical chains. Isomorphic compounds 3 and 4 show 3,4-connected 2D new topology with the point symbol of (4(2)·6(3)·8)(4(2)·6). Multicolor luminescence can be tailored from red to green regions by singly varying the mixing molar ratio of Eu(III)/Tb(III) cations. The mixing component of 1Eu/2Tb = 4:6 not only achieves white-light emission with the CIE coordinate of (0.323, 0.339) upon excitation at 405 nm but also presents a temperature recognition property with the significantly high sensitivity of 0.68% per K in the 50-225 K temperature range upon excitation at 370 nm.

Irradiance optimization of outdoor microalgal cultures using solar tracked photobioreactors.

PubMed

Hindersin, Stefan; Leupold, Marco; Kerner, Martin; Hanelt, Dieter

2013-03-01

Photosynthetic activity and temperature regulation of microalgal cultures (Chlorella vulgaris and Scenedesmus obliquus) under different irradiances controlled by a solar tracker and different cell densities were studied in outdoor flat panel photobioreactors. An automated process control unit regulated light and temperature as well as pH value and nutrient concentration in the culture medium. CO2 was supplied using flue gas from an attached combined block heat and power station. Photosynthetic activity was determined by pulse amplitude modulation fluorometry. Compared to the horizontal irradiance of 55 mol photons m(-2) d(-1) on a clear day, the solar tracked photobioreactors enabled a decrease and increase in the overall light absorption from 19 mol photons m(-2) d(-1) (by rotation out of direct irradiance) to 79 mol photons m(-2) d(-1) (following the position of the sun). At biomass concentrations below 1.1 g cell dry weight (CDW) L(-1), photoinhibition of about 35 % occurred at irradiances of ≥1,000 μmol photons m(-2) s(-1) photosynthetic active radiation (PAR). Using solar tracked photobioreactors, photoinhibition can be reduced and at optimum biomass concentration (≥2.3 g CDW L(-1)), the culture was irradiated up to 2,000 μmol photons m(-2) s(-1) to overcome light limitation with biomass yields of 0.7 g CDW mol photons(-1) and high photosynthetic activities indicated by an effective quantum yield of 0.68 and a maximum quantum yield of 0.80 (F v/F m). Overheating due to high irradiance was avoided by turning the PBR out of the sun or using a cooling system, which maintained the temperature close to the species-specific temperature optima.

Temperature Oscillation Modulated Self-Assembly of Periodic Concentric Layered Magnesium Carbonate Microparticles

PubMed Central

Li, Shihong; Wang, Zheng Jim; Chang, Ting-Tung

2014-01-01

Intriguing patterns of periodic, concentric, layered, mineral microstructure are present in nature and organisms, yet they have elusive geneses. We hypothesize temperature oscillation can be an independent factor that causes the self-assembly of such patterns in mineral phases synthesized in solution. Static experiments verify that rhythmic concentric multi-layered magnesium carbonate microhemispheres can be synthesized from bicarbonate solution by temperature oscillation, without use of a chemical template, additive or gel-diffusion system. Appropriate reactant concentration and initial pH value can restrain the competitive growth of other mineral generations. Polarized light microscopy images indicate the microhemispheres are crystalline and the crystallinity increases with incubation time. The thickness of a single mineral layer of microhemisphere in microscale is precisely controlled by the waveform parameters of the temperature oscillation, while the layer number, which can reach tens to about one hundred, is constrained by the temperature oscillation period number. FT-IR spectra show that these microhemispheres synthesized under different conditions can be identified as the basic form of magnesium carbonate, hydromagnesite (Mg5(CO3)4(OH)2⋅4H2O). SEM images exhibit the characteristic microscopic texture of the alternating dark and light rings of these microhemispheres. TEM images and ED patterns suggest the nanoflakes of microhemispheres are present in polycrystalline form with some degree of oriented assembly. The temperature oscillation modulated self-assembly may offer a new mechanism to understand the formation of layered microstructure of minerals in solution, and provide a non-invasive and programmable means to synthesize hierarchically ordered materials. PMID:24520410

Light intensity as major factor to maximize biomass and lipid productivity of Ettlia sp. in CO2-controlled photoautotrophic chemostat.

PubMed

Seo, Seong-Hyun; Ha, Ji-San; Yoo, Chan; Srivastava, Ankita; Ahn, Chi-Yong; Cho, Dae-Hyun; La, Hyun-Joon; Han, Myung-Soo; Oh, Hee-Mock

2017-11-01

The optimal culture conditions are critical factors for high microalgal biomass and lipid productivity. To optimize the photoautotrophic culture conditions, combination of the pH (regulated by CO 2 supply), dilution rate, and light intensity was systematically investigated for Ettlia sp. YC001 cultivation in a chemostat during 143days. The biomass productivity increased with the increase in dilution rate and light intensity, but decreased with increasing pH. The average lipid content was 19.8% and statistically non-variable among the tested conditions. The highest biomass and lipid productivities were 1.48gL -1 d -1 and 291.4mgL -1 d -1 with a pH of 6.5, dilution rate of 0.78d -1 , and light intensity of 1500μmolphotonsm -2 s -1 . With a sufficient supply of CO 2 and nutrients, the light intensity was the main determinant of the photosynthetic rate. Therefore, the surface-to-volume ratio of a photobioreactor should enable efficient light distribution to enhance microalgal growth. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temperature modulates the response of the thermophilous sea urchin Arbacia lixula early life stages to CO2-driven acidification.

PubMed

Gianguzza, Paola; Visconti, Giulia; Gianguzza, Fabrizio; Vizzini, Salvatrice; Sarà, Gianluca; Dupont, Sam

2014-02-01

The increasing abundances of the thermophilous black sea urchin Arbacia lixula in the Mediterranean Sea are attributed to the Western Mediterranean warming. However, few data are available on the potential impact of this warming on A. lixula in combination with other global stressors such as ocean acidification. The aim of this study is to investigate the interactive effects of increased temperature and of decreased pH on fertilization and early development of A. lixula. This was tested using a fully crossed design with four temperatures (20, 24, 26 and 27 °C) and two pH levels (pHNBS 8.2 and 7.9). Temperature and pH had no significant effect on fertilization and larval survival (2d) for temperature <27 °C. At 27 °C, the fertilization success was very low (<1%) and all larvae died within 2d. Both temperature and pH had effects on the developmental dynamics. Temperature appeared to modulate the impact of decreasing pH on the % of larvae reaching the pluteus stage leading to a positive effect (faster growth compared to pH 8.2) of low pH at 20 °C, a neutral effect at 24 °C and a negative effect (slower growth) at 26 °C. These results highlight the importance of considering a range of temperatures covering today and the future environmental variability in any experiment aiming at studying the impact of ocean acidification. Copyright © 2013 Elsevier Ltd. All rights reserved.

Direct 1H NMR evidence of spin-rotation coupling as a source of para → ortho-H2 conversion in diamagnetic solvents

NASA Astrophysics Data System (ADS)

Terenzi, Camilla; Bouguet-Bonnet, Sabine; Canet, Daniel

2017-04-01

At ambient temperature, conversion from 100% enriched para-hydrogen (p-H2; singlet state) to ortho-hydrogen (o-H2; triplet state) leads necessarily to the thermodynamic equilibrium proportions: 75% of o-H2 and 25% of p-H2. When p-H2 is dissolved in a diamagnetic organic solvent, conversion is very slow and can be considered as arising from nuclear spin relaxation phenomena. A first relaxation mechanism, specific to the singlet state and involving a combination of auto-correlation and cross correlation spectral densities, can be retained: randomly fluctuating magnetic fields due to inter-molecular dipolar interactions. We demonstrate here that (i) this dipolar mechanism is not sufficient for accounting for the p a r a →o r t h o conversion rate, (ii) spin-rotation interaction, an intra-molecular mechanism, behaves similarly to random-field interaction and, thus, may be involved in the singlet relaxation rate. Also, as the p a r a →o r t h o conversion is monitored by proton nuclear magnetic resonance (NMR) of dissolved o-H2 (p-H2 is NMR-silent), one has to account for H2 exchange between the liquid phase and the gas phase within the NMR tube, as well as for dissolution effects. Experimental evidence of the above statements is brought here in the case of two organic solvents: acetone-d6 and carbon disulfide. The observed temperature dependence of the p a r a →o r t h o conversion rate shows that spin-rotation can be the dominant contribution to the p-H2 relaxation rate in the absence of tangible dipolar interactions. Our findings shed new light on the "mysterious" mechanism of the p a r a →o r t h o conversion which has been searched for several decades.

Facile chemical approach to ZnO submicrometer particles with controllable morphologies.

PubMed

Bardhan, Rizia; Wang, Hui; Tam, Felicia; Halas, Naomi J

2007-05-22

We have developed a simple wet-chemistry approach to fabricating ZnO submicrometer particles with unique morphologies including rings, bowls, hemispheres, and disks. The size and morphology of the particles can be conveniently tailored by varying the concentrations of the zinc precursor. The reaction temperature, pH, and concentration of ammonia are also found to play critical roles in directing the formation of these particle morphologies. These submicrometer particles exhibit strong white-light emission upon UV excitation as a result of the presence of surface defect states resulting from the fabrication method and synthesis conditions.

Gelation of Regenerated Fibroin Solution

NASA Astrophysics Data System (ADS)

Nagarkar, Shailesh; Lele, Ashish; Chassenieux, Christophe; Nicolai, Taco; Durand, Dominique

2008-07-01

Silk fibroin is a high molecular weight multiblock ampiphillic protein known for its ability to form high strength fibers. It is also biocompatible; silk sutures have been traditionally used for many centuries. Recently, there has been much interest in making silk hydrogels for applications ranging from tissue engineering to controlled delivery. Fibroin gels can be formed from aqueous solutions by changing one or more state variables such as pH, temperature and ionic strength. In this work we present our investigations on the gelation of aqueous fibroin solutions derived from Bombyx Mori silk using light scattering, confocal microscopy and rheological techniques.

Temperature influences neuronal activity and CO2/pH sensitivity of locus coeruleus neurons in the bullfrog, Lithobates catesbeianus.

PubMed

Santin, Joseph M; Watters, Kayla C; Putnam, Robert W; Hartzler, Lynn K

2013-12-15

The locus coeruleus (LC) is a chemoreceptive brain stem region in anuran amphibians and contains neurons sensitive to physiological changes in CO2/pH. The ventilatory and central sensitivity to CO2/pH is proportional to the temperature in amphibians, i.e., sensitivity increases with increasing temperature. We hypothesized that LC neurons from bullfrogs, Lithobates catesbeianus, would increase CO2/pH sensitivity with increasing temperature and decrease CO2/pH sensitivity with decreasing temperature. Further, we hypothesized that cooling would decrease, while warming would increase, normocapnic firing rates of LC neurons. To test these hypotheses, we used whole cell patch-clamp electrophysiology to measure firing rate, membrane potential (V(m)), and input resistance (R(in)) in LC neurons in brain stem slices from adult bullfrogs over a physiological range of temperatures during normocapnia and hypercapnia. We found that cooling reduced chemosensitive responses of LC neurons as temperature decreased until elimination of CO2/pH sensitivity at 10°C. Chemosensitive responses increased at elevated temperatures. Surprisingly, chemosensitive LC neurons increased normocapnic firing rate and underwent membrane depolarization when cooled and decreased normocapnic firing rate and underwent membrane hyperpolarization when warmed. These responses to temperature were not observed in nonchemosensitive LC neurons or neurons in a brain stem slice 500 μm rostral to the LC. Our results indicate that modulation of cellular chemosensitivity within the LC during temperature changes may influence temperature-dependent respiratory drive during acid-base disturbances in amphibians. Additionally, cold-activated/warm-inhibited LC neurons introduce paradoxical temperature sensitivity in respiratory control neurons of amphibians.

Temperature sensitivity of organic substrate decay varies with pH

NASA Astrophysics Data System (ADS)

Min, K.; Lehmeier, C.; Ballantyne, F.; Billings, S. A.

2012-12-01

Cellulose is the most abundant biopolymer in soils and globally ubiquitous. It serves as a primary carbon source for myriad microbes able to release cellulases which cleave the cellulose into smaller molecules. For example, β-glucosidase, one type of cellulase, breaks down a terminal β-glycosidic bond of cellulose. The carbon of the liberated glucose becomes available for microbial uptake, after which it can then be mineralized and returned to the atmosphere via heterotrophic respiration. Thus, exoenzymes play an important role in the global cycling of carbon. Numerous studies suggest that global warming potentially increases the rate at which β-glucosidase breaks down cellulose, but it is not known how pH of the soil solution influences the effect of temperature on cellulose decomposition rates; this is important given the globally wide range of soil pH. Using fluorescence enzyme assay techniques, we studied the effect of temperature and pH on the reaction rate at which purified β-Glucosidase decays β-D-cellobioside (a compound often employed to simulate cellulose). We evaluated the temperature sensitivity of this reaction at five temperatures (5, 10, 15, 20, and 25°C) and six pH values (3.5, 4.5, 5.5, 6.5, 7.5, and 8.5)encompassing the naturally occurring range in soils, in a full-factorial design. First, we determined Vmax at 25°C and pH 6.5, standard conditions for measuring enzyme activities in many studies. The Vmax was 858.65 μmol h-1mg-1and was achieved at substrate concentration of 270 μM. At all pH values, the reaction rate slowed down at lower temperatures; at a pH of 3.5, no enzymatic activity was detected. The enzyme activity was significantly different between pH 4.5 and higher pHs. For example, enzyme reactivity at pH 4.5 was significantly lower than that at 7.5 at 20 and 25°C (Bonferroni-corrected P =0.0006, 0.0004, respectively), but not at lower temperatures. Similarly, enzyme reactivity at pH 4.5 was lower than that at pH 8.5 at 10, 15, and 25°C (P=0.0009, 0.0007, 0.0005, respectively), with a near-significant trend at 20°C (P=0.0023), and exhibited a nearly significant depression in response to temperature at 25°C compared to that at pH 6.5 (P=0.0015). Our results suggest that exoenzymatic cellulose decomposition with warming may be more enhanced in soil systems exhibiting higher pH. This work highlights the importance of soil solution pH as a driver of temperature sensitivity of substrate decay, and adds a level of complexity for developing accurate predictions of soil carbon cycling with climate change.

Determinants of disinfectant pretreatment efficacy for nitrosamine control in chloraminated drinking water.

PubMed

McCurry, Daniel L; Krasner, Stuart W; von Gunten, Urs; Mitch, William A

2015-11-01

Utilities using chloramines need strategies to mitigate nitrosamine formation to meet potential future nitrosamine regulations. The ability to reduce NDMA formation under typical post-chloramination conditions of pretreatment with ultraviolet light from a low pressure mercury lamp (LPUV), free chlorine (HOCl), ozone (O3), and UV light from a medium pressure mercury lamp (MPUV) were compared at exposures relevant to drinking water treatment. The order of efficacy after application to waters impacted by upstream wastewater discharges was O3 > HOCl ≈ MPUV > LPUV. NDMA precursor abatement generally did not correlate well between oxidants, and waters exhibited different behaviors with respect to pH and temperature, suggesting a variety of source-dependent NDMA precursors. For wastewater-impacted waters, the observed pH dependence for precursor abatement suggested the important role of secondary or tertiary amine precursors. Although hydroxyl radicals did not appear to be important for NDMA precursor abatement during O3 or MPUV pretreatment, the efficacy of MPUV correlated strongly with dissolved organic carbon concentration (p = 0.01), suggesting alternative indirect photochemical pathways. The temperature dependences during pre- and post-disinfection indicated that NDMA formation is likely to increase during warm seasons for O3 pretreatment, decrease for HOCl pretreatment, and remain unchanged for MPUV treatment, although seasonal changes in source water quality may counteract the temperature effects. For two waters impacted by relatively high polyDADMAC coagulant doses, pretreatment with HOCl, O3, and MPUV increased NDMA formation during post-chloramination. For O3 pretreatment, hydroxyl radicals likely led to precursor formation from the polymer in the latter tests. MPUV treatment of polymer-impacted water increased subsequent NDMA formation through an indirect photochemical process. Many factors may mitigate the importance of this increased NDMA formation, including the low polyDADMAC doses typically applied, and simultaneous degradation of watershed-associated precursors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Combined effects of ocean acidification and temperature on planula larvae of the moon jellyfish Aurelia coerulea.

PubMed

Dong, Zhijun; Sun, Tingting

2018-08-01

Rapidly rising levels of atmospheric CO 2 have caused two environmental stressors, ocean acidification and seawater temperature increases, which represent major abiotic threats to marine organisms. Here, we investigated for the first time the combined effects of ocean acidification and seawater temperature increases on the behavior, survival, and settlement of the planula larvae of Aurelia coerulea, which is considered a nuisance species around the world. Three pH levels (8.1, 7.7 and 7.3) and two temperature levels (24 °C and 27 °C) were used in the present study. There were no interactive effects of temperature and pH on the behavior, survival, and settlement of planula larvae of A. coerulea. We found that the swimming speed and mortality of the planula larvae of A. coerulea were significantly affected by temperature, and low pH significantly affected settlement. Planula larvae of A. coerulea from the elevated temperature treatment moved faster and showed higher mortality than those at the control temperature. The settlement rate of A. coerulea planulae was significantly higher at the pH level of 7.3 than at other pH levels. These results suggest that seawater temperature increase, rather than reduced pH, was the main stress factor affecting the survival of A. coerulea planulae. Overall, the planula larvae of the common jellyfish A. coerulea appeared to be resistant to ocean acidification, but may be negatively affected by future seawater temperature increases. Copyright © 2018 Elsevier Ltd. All rights reserved.

How pH, Temperature, and Time of Incubation Affect False-Positive Responses and Uncertainty of the LAL Gel-Clot Test.

PubMed

Lourenço, Felipe Rebello; Botelho, Túlia De Souza; Pinto, Terezinha De Jesus Andreoli

2012-01-01

The limulus amebocyte lysate (LAL) test is the simplest and most widely used procedure for detection of endotoxin in parenteral drugs. The LAL test demands optimal pH, ionic strength, temperature, and time of incubation. Slight changes in these parameters may increase the frequency of false-positive responses and the estimated uncertainty of the LAL test. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. LAL tests were performed in nominal conditions (37 °C, 60 min, and pH 7) and in different conditions of temperature (36 °C and 38 °C), time of incubation (58 and 62 min), and pH (6 and 8). Slight differences in pH increase the frequency of false-positive responses 5-fold (relative risk 5.0), resulting in an estimated of uncertainty 7.6%. Temperature and time of incubation affect the LAL test less, showing relative risks of 1.5 and 1.0, respectively. Estimated uncertainties in 36 °C or 38 °C temperatures and 58 or 62 min of incubation were found to be 2.0% and 1.0%, respectively. Simultaneous differences in these parameters significantly increase the frequency of false-positive responses. The limulus amebocyte lysate (LAL) gel-clot test is a simple test for detection of endotoxin from Gram-negative bacteria. The test is based on a gel formation when a certain amount of endotoxin is present; it is a pass/fail test. The LAL test requires optimal pH, ionic strength, temperature, and time of incubation. Slight difference in these parameters may increase the frequency of false-positive responses. The aim of this paper is to evaluate how changes in the pH, temperature, and time of incubation affect the occurrence of false-positive responses in the LAL test. We find that slight differences in pH increase the frequency of false-positive responses 5-fold. Temperature and time of incubation affect the LAL test less. Simultaneous differences in these parameters significantly increase the frequency of false-positive responses.

Expression and testing in plants of ArcLight, a genetically-encoded voltage indicator used in neuroscience research.

PubMed

Matzke, Antonius J M; Matzke, Marjori

2015-10-12

It is increasingly appreciated that electrical controls acting at the cellular and supra-cellular levels influence development and initiate rapid responses to environmental cues. An emerging method for non-invasive optical imaging of electrical activity at cell membranes uses genetically-encoded voltage indicators (GEVIs). Developed by neuroscientists to chart neuronal circuits in animals, GEVIs comprise a fluorescent protein that is fused to a voltage-sensing domain. One well-known GEVI, ArcLight, undergoes strong shifts in fluorescence intensity in response to voltage changes in mammalian cells. ArcLight consists of super-ecliptic (SE) pHluorin (pH-sensitive fluorescent protein) with an A227D substitution, which confers voltage sensitivity in neurons, fused to the voltage-sensing domain of the voltage-sensing phosphatase of C iona i ntestinalis (Ci-VSD). In an ongoing effort to adapt tools of optical electrophysiology for plants, we describe here the expression and testing of ArcLight and various derivatives in different membranes of root cells in Arabidopsis thaliana. Transgenic constructs were designed to express ArcLight and various derivatives targeted to the plasma membrane and nuclear membranes of Arabidopsis root cells. In transgenic seedlings, changes in fluorescence intensity of these reporter proteins following extracellular ATP (eATP) application were monitored using a fluorescence microscope equipped with a high speed camera. Coordinate reductions in fluorescence intensity of ArcLight and Ci-VSD-containing derivatives were observed at both the plasma membrane and nuclear membranes following eATP treatments. However, similar responses were observed for derivatives lacking the Ci-VSD. The dispensability of the Ci-VSD suggests that in plants, where H(+) ions contribute substantially to electrical activities, the voltage-sensing ability of ArcLight is subordinate to the pH sensitivity of its SEpHluorin base. The transient reduction of ArcLight fluorescence triggered by eATP most likely reflects changes in pH and not membrane voltage. The pH sensitivity of ArcLight precludes its use as a direct sensor of membrane voltage in plants. Nevertheless, ArcLight and derivatives situated in the plasma membrane and nuclear membranes may offer robust, fluorescence intensity-based pH indicators for monitoring concurrent changes in pH at these discrete membrane systems. Such tools will assist analyses of pH as a signal and/or messenger at the cell surface and the nuclear periphery in living plants.

Effects of niacin supplementation and dietary concentrate proportion on body temperature, ruminal pH and milk performance of primiparous dairy cows.

PubMed

Lohölter, Malte; Meyer, Ulrich; Rauls, Caroline; Rehage, Jürgen; Dänicke, Sven

2013-06-01

The objective of this study was to investigate the effects of niacin and dietary concentrate proportion on body temperature, ruminal pH and milk production of dairy cows. In a 2 × 2 factorial design, 20 primiparous Holstein cows (179 ± 12 days in milk) were assigned to four dietary treatments aimed to receive either 0 or 24 g niacin and 30% (low) or 60% (high) concentrate with the rest being a partial mixed ration (PMR) composed of 60% corn and 40% grass silage (on dry matter basis). Ambient temperature and relative humidity were determined and combined by the calculation of temperature humidity index. Respiration rates, rectal, skin and subcutaneous temperatures were measured. Milk production and composition were determined. Ruminal pH and temperature were recorded at a frequency of 5 min using wireless devices for continuous intra-ruminal measurement (boluses). pH values were corrected for pH sensor drift. The climatic conditions varied considerably but temporarily indicated mild heat stress. Niacin did not affect skin, rectal and subcutaneous temperatures but tended to increase respiration rates. High concentrate reduced skin temperatures at rump, thigh and neck by 0.1-0.3°C. Due to the technical disturbances, not all bolus data could be subjected to statistical evaluation. However, both niacin and high concentrate influenced mean ruminal pH. High concentrate increased the time spent with a pH below 5.6 and ruminal temperatures (0.2-0.3°C). Niacin and high concentrate enhanced milk, protein and lactose yield but reduced milk fat and protein content. Milk fat yield was slightly reduced by high concentrate but increased due to niacin supplementation. In conclusion, niacin did not affect body temperature but stimulated milk performance. High concentrate partially influenced body temperatures and had beneficial effects on milk production.

Electrical Transport Mechanisms and Photoconduction in Undoped Crystalline Flash-Evaporated Lead Iodide Thin Films

NASA Astrophysics Data System (ADS)

Al-Daraghmeh, Tariq M.; Saleh, Mahmoud H.; Ahmad, Mais Jamil A.; Bulos, Basim N.; Shehadeh, Khawla M.; Jafar, Mousa M. Abdul-Gader

2018-03-01

The flash-evaporation technique was utilized to fabricate undoped 1.35-μm and 1.2-μm thick lead iodide films at substrate temperatures T_{{s}} = 150 °C and 200°C, respectively. The films were deposited onto a coplanar comb-like copper (Cu-) electrode pattern, previously coated on glass substrates to form lateral metal-semiconductor-metal (MSM-) structures. The as-measured constant- temperature direct-current (dc)-voltage ( I( {V;T} ) - V ) curves of the obtained lateral coplanar Cu-PbI2-Cu samples (film plus electrode) displayed remarkable ohmic behavior at all temperatures ( T = 18 - 90°C). Their dc electrical resistance R_{{dc}} (T ) revealed a single thermally-activated conduction mechanism over the temperature range with activation energy E_{{act}} ≈ 0.90 - 0.98 {eV} , slightly less than half of room-temperature bandgap energy E_{{g}} ( ≈ 2.3 {eV} ) of undoped 2H-polytype PbI2 single crystals. The undoped flash-evaporated {PbI}_{{x}} thin films were homogeneous and almost stoichiometric ( x ≈ 1.87 ), in contrast to findings on lead iodide films prepared by other methods, and were highly crystalline hexagonal 2H-polytypic structure with c-axis perpendicular to the surface of substrates maintained at T_{s} ≳ 150°C. Photoconductivity measurements made on these lateral Cu-PbI2-Cu-structures under on-off visible-light illumination reveal a feeble photoresponse for long wavelengths ( λ > 570 {nm} ), but a strong response to blue light of photon energy E_{{ph}} ≈ 2.73 {eV} ( > E_{{g}} ), due to photogenerated electron-hole (e-h) pairs via direct band-to-band electronic transitions. The constant-temperature/dc voltage current-time I( {T,V} ) - t curves of the studied lateral PbI2 MSM-structures at low ambient temperatures ( T < 50°C), after cutting off the blue-light illumination, exhibit two trapping mechanisms with different relaxation times. These strongly depend on V and T , with thermally generated charge carriers in the PbI2 mask photogenerated (e-h) pairs at higher temperatures.

Sporulation boundaries and spore formation kinetics of Bacillus spp. as a function of temperature, pH and a(w).

PubMed

Baril, Eugénie; Coroller, Louis; Couvert, Olivier; El Jabri, Mohammed; Leguerinel, Ivan; Postollec, Florence; Boulais, Christophe; Carlin, Frédéric; Mafart, Pierre

2012-10-01

Sporulation niches in the food chain are considered as a source of hazard and are not clearly identified. Determining the sporulation environmental boundaries could contribute to identify potential sporulation niches. Spore formation was determined in a Sporulation Mineral Buffer. The effect of incubation temperature, pH and water activity on time to one spore per mL, maximum sporulation rate and final spore concentration was investigated for a Bacillus weihenstephanensis and a Bacillus licheniformis strain. Sporulation boundaries of B. weihenstephanensis and of B. licheniformis were similar to, or included within, the range of temperatures, pH and water activities supporting growth. For instance, sporulation boundaries of B. weihenstephanensis were evaluated at 5°C, 35°C, pH 5.2 and a(w) 0.960 while growth boundaries were observed at 5°C, 37°C, pH 4.9 and a(w) 0.950. Optimum spore formation was determined at 30°C pH 7.2 for B. weihenstephanensis and at 45°C pH 7.2 for B. licheniformis. Lower temperatures and pH delayed the sporulation process. For instance, the time to one spore per mL was tenfold longer when sporulation occurred at 10°C and 20°C, for each strain respectively, than at optimum sporulation temperature. The relative effect of temperature and pH on sporulation rates and on growth rates is similar. This work suggests that the influence of environmental factors on the quantitative changes in sporulation boundaries and rates was similar to their influence on changes in growth rate. Copyright © 2012 Elsevier Ltd. All rights reserved.

Photocatalytic hydrogen production from biomass-derived compounds: a case study of citric acid.

PubMed

Alkaim, Ayad F; Kandiel, Tarek A; Dillert, Ralf; Bahnemann, Detlef W

2016-11-01

Highly crystalline anatase TiO2 nanoparticles with high BET surface area have been synthesized by thermal hydrolysis of titanium(IV) bis(ammoniumlactato) dihydroxide aqueous solutions. The photocatalytic H2 production from aqueous citric acid (CA) solutions over Pt-loaded TiO2 has been investigated under different experimental conditions, that is, different CA concentration, temperature, light intensity, and pH of Pt/TiO2 suspension. For comparison, the photocatalytic dehydrogenation of triethanolamine (TEA) has also been investigated. The highest H2 production rates were obtained at pH 3 and 9 for CA and TEA, respectively. This behavior is readily explained by the adsorption characteristic of the employed reagent on the surface of the charged TiO2. The effect of the photocatalyst loading and the light intensity on the H2 production rate showed the same behavior in the case of CA and TEA evincing that these parameters are catalyst dependent. The apparent activation energies have been determined to be 13.5 ± 1.8 and 14.7 ± 1.6 kJ mol(-1) for CA and TEA, respectively, indicating the existence of an activation energy barrier in a photocatalytic process which can be attributed to the desorption of adsorbed products.

Yield and cold storage of Trichoderma conidia is influenced by substrate pH and storage temperature.

PubMed

Steyaert, Johanna M; Chomic, Anastasia; Nieto-Jacobo, Maria; Mendoza-Mendoza, Artemio; Hay, Amanda J; Braithwaite, Mark; Stewart, Alison

2017-05-01

In this study we examined the influence of the ambient pH during morphogenesis on conidial yield of Trichoderma sp. "atroviride B" LU132 and T. hamatum LU593 and storage at low temperatures. The ambient pH of the growth media had a dramatic influence on the level of Trichoderma conidiation and this was dependent on the strain and growth media. On malt-extract agar, LU593 yield decreased with increasing pH (3-6), whereas yield increased with increasing pH for LU132. During solid substrate production the reverse was true for LU132 whereby yield decreased with increasing pH. The germination potential of the conidia decreased significantly over time in cold storage and the rate of decline was a factor of the strain, pH during morphogenesis, growth media, and storage temperature. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ab initio determination of effective electron-phonon coupling factor in copper

NASA Astrophysics Data System (ADS)

Ji, Pengfei; Zhang, Yuwen

2016-04-01

The electron temperature Te dependent electron density of states g (ε), Fermi-Dirac distribution f (ε), and electron-phonon spectral function α2 F (Ω) are computed as prerequisites before achieving effective electron-phonon coupling factor Ge-ph. The obtained Ge-ph is implemented into a molecular dynamics (MD) and two-temperature model (TTM) coupled simulation of femtosecond laser heating. By monitoring temperature evolutions of electron and lattice subsystems, the result utilizing Ge-ph from ab initio calculation shows a faster decrease of Te and increase of Tl than those using Ge-ph from phenomenological treatment. The approach of calculating Ge-ph and its implementation into MD-TTM simulation is applicable to other metals.

An investigation into the potential of phenothiazinium-based photo-sensitisers to act as PDT agents.

PubMed

Harris, F; Sayed, Z; Hussain, S; Phoenix, D A

2004-11-01

There is an urgent need for effective cancer treatments and increasingly, photo-dynamic therapy (PDT) is being used to fulfil this need as it offers a number of advantages over traditional cancer treatments. Here, the potential of a series of phenothiazinium-based photo-sensitisers (PhBPs) as PDT agents is tested. PhBPs were incubated with EMT-6 tumour cells and erythrocytes respectively under dark and light conditions (3.15Jcm(-2) over 30min). "Comet assay" and haemolytic assay were then used to assess cellular photo-damage induced by these PhBPs. Additionally, in vitro assays were used to determine light adsorption characteristics, singlet oxygen yields (ΦΔPhBP) and lipophilicity (logP) of these PhBPs. "Comet assay" showed EMT-6 incubation with PhBPs under light conditions to produce DNA "tails", which were circa 35μm long, indicating the presence of DNA photo-damage. Corresponding incubations under dark conditions led to no such damage. The majority of the PhBPs tested possessed significant singlet oxygen yields (ΦΔPhBP>0.7), suggesting the general use of type II mechanisms for photo-sensitization, and were generally lipophilic (logP>0). Incubation of erythrocytes with these PhBPs in the dark produced between 6% and 19% haemolysis. These levels were generally unaffected by illumination except in the case of DMMB, which showed haemolytic levels increasing from 11% to 61%. It is suggested that DNA may be the primary target for the photo-dynamic anti-tumour activity of the PhBPs tested with the exception of DMMB, which may potentially also target tumour cell membranes.

Temperature and pH effects on feeding and growth of Antarctic krill

NASA Astrophysics Data System (ADS)

Saba, G.; Bockus, A.; Fantasia, R. L.; Shaw, C.; Sugla, M.; Seibel, B.

2016-02-01

Rapid warming in the Western Antarctic Peninsula (WAP) region is occurring, and is associated with an overall decline in primary, secondary, and higher trophic levels, including Antarctic krill (Euphausia superba), a key species in Antarctic food webs. Additionally, there are predictions that by the end of this century the Southern Ocean will be one of the first regions to be affected by seawater chemistry changes associated with enhanced CO2. Ocean acidification and warming may act synergistically to impair animal performance, which may negatively impact Antarctic krill. We assessed the effects of temperature (ambient temperature, ambient +3 degrees C) and pH (Experiment 1 = 8.0, 7.7; Experiment 2 = 8.0, 7.5, 7.1) on juvenile Antarctic krill feeding and growth (growth increment and intermolt period) during incubation experiments at Palmer Station, Antarctica. Food intake was lower in krill exposed to reduced pH. Krill intermolt period (IMP) was significantly lower in the elevated temperature treatments (16.9 days) compared to those at 0 degrees (22.8 days). Within the elevated temperature treatment, minor increases in IMP occurred in krill exposed reduced pH. Growth increment (GI) was lower with decreased pH at the first molt, and this was exacerbated at elevated temperature. However, differences in GI were eliminated between the first and second molts suggesting potential ability of Antarctic krill to acclimate to changes in temperature and pH. Reductions in juvenile krill growth and feeding under elevated temperature and reduced pH are likely caused by higher demands for internal acid-base regulation or a metabolic suppression. However, the subtlety of these feeding and growth responses leaves an open question as to how krill populations will tolerate prolonged future climate change in the Antarctic.

A novel approach for stabilizing fresh urine by calcium hydroxide addition

PubMed Central

Randall, Dyllon G.; Krähenbühl, Manuel; Köpping, Isabell; Larsen, Tove A.; Udert, Kai M.

2016-01-01

In this study, we investigated the prevention of enzymatic urea hydrolysis in fresh urine by increasing the pH with calcium hydroxide (Ca(OH)2) powder. The amount of Ca(OH)2 dissolving in fresh urine depends significantly on the composition of the urine. The different urine compositions used in our simulations showed that between 4.3 and 5.8 g Ca(OH)2 dissolved in 1 L of urine at 25 °C. At this temperature, the pH at saturation is 12.5 and is far above the pH of 11, which we identified as the upper limit for enzymatic urea hydrolysis. However, temperature has a strong effect on the saturation pH, with higher values being achieved at lower temperatures. Based on our results, we recommend a dosage of 10 g Ca(OH)2 L−1 of fresh urine to ensure solid Ca(OH)2 always remains in the urine reactor which ensures sufficiently high pH values. Besides providing sufficient Ca(OH)2, the temperature has to be kept in a certain range to prevent chemical urea hydrolysis. At temperatures below 14 °C, the saturation pH is higher than 13, which favors chemical urea hydrolysis. We chose a precautionary upper temperature of 40 °C because the rate of chemical urea hydrolysis increases at higher temperatures but this should be confirmed with kinetic studies. By considering the boundaries for pH and temperature developed in this study, urine can be stabilized effectively with Ca(OH)2 thereby simplifying later treatment processes or making direct use easier. PMID:27055084

Temperature range and degree of acidity growth of isolate of indigenous bacteria on fermented feed “fermege”

NASA Astrophysics Data System (ADS)

Isnawati; Trimulyono, G.

2018-01-01

Fermege is a fermented feed of ruminants, especially goats made from water hyacinth (Eichhornia crassipes). Temperature range and pH need to know in making starter formula for acceleration of fermentation process at making ruminant feed made from this materials. The starter formula expired period can be extended by adjusting starter storage temperature and pH of the starter. This research was aimed to find the temperature and pH range for the growth of isolate of indigenous bacteria “fermege.” This research is an explorative research conducted by growing bacteria isolate indigenous fermege in liquid medium with various pH and incubation in various temperature. Bacterial population was calculated based on turbidity of bacterial suspension with turbidometer. The stages of this research were to isolate the bacteria present in the fermege, purify the isolates found, and then grow the isolates in a liquid medium with various pH values. The isolated bacterials were incubated at different temperature variations. The cell population density of the isolates was calculated after incubation for 24 hours. The results showed there were eight indigenous bacterial isolates. All isolates can grow in the pH range 6 and 7. Two isolates (Bacillus subtilis and B. pumilus) can grow at 4°C. All isolates obtained can grow at a temperature of 30°C. Isolates Bacillus badius, B. subtilis, B. cereus, Pseudomonas stutzeri and P. diminuta can grow at 50°C. Based on research indicates that indigenous fermege bacterial isolates have the ability to grow in the neutral pH range and temperature range between 4°C and 50°C.

Finding stable cellulase and xylanase: evaluation of the synergistic effect of pH and temperature.

PubMed

Farinas, Cristiane S; Loyo, Marcel Moitas; Baraldo, Anderson; Tardioli, Paulo W; Neto, Victor Bertucci; Couri, Sonia

2010-12-31

Ethanol from lignocellulosic biomass has been recognized as one of the most promising alternatives for the production of renewable and sustainable energy. However, one of the major bottlenecks holding back its commercialization is the high costs of the enzymes needed for biomass conversion. In this work, we studied the enzymes produced from a selected strain of Aspergillus niger under solid state fermentation. The cellulase and xylanase enzymatic cocktail was characterized in terms of pH and temperature by using response surface methodology. Thermostability and kinetic parameters were also determined. The statistical analysis of pH and temperature effects on enzymatic activity showed a synergistic interaction of these two variables, thus enabling to find a pH and temperature range in which the enzymes have a higher activity. The results obtained allowed the construction of mathematical models used to predict endoglucanase, β-glucosidase and xylanase activities under different pH and temperature conditions. Optimum temperature values for all three enzymes were found to be in the range between 35°C and 60°C, and the optimum pH range was found between 4 and 5.5. The methodology employed here was very effective in estimating enzyme behavior under different process conditions. Copyright © 2010 Elsevier B.V. All rights reserved.

Light-induced Changes in Allophycocyanin 1

PubMed Central

Ohad, Itzhak; Schneider, Hans-Jörg A. W.; Gendel, Steven; Bogorad, Lawrence

1980-01-01

Several lines of evidence indicate that allophycocyanin is the previously unidentified “phycochrome” observed in extracts of blue-green algae. Fractions containing phycoerythrin, phycocyanin, and allophycocyanin and exhibiting light-induced absorbance changes were prepared from extracts of Nostoc muscorum and Fremyella diplosiphon by isoelectric focusing. Illumination of such fractions with red light (650 nanometers) causes a reduction in absorbance at 620 nm (≃1 to 2%) and an increase at 560 nm. The effect, (previously observed by Björn and Björn [1976 Physiol Plant 36: 297-304]) is reversible, upon illumination with green light (550 nm). Selective immunoprecipitation of the phycobiliproteins indicates that allophycocyanin is the photoresponsive pigment. At pH 4.0 to 4.2, allophycocyanin purified from the same algae or from Phormidium luridum exhibits a light-induced absorbance change at 620 nm, which coincides with its absorption maximum at this pH; the fluorescence emission of allophycocyanin under these conditions is at 647 nm and its S20,w is 2.28, compatible with an α1β1 polypeptide composition. At neutral pH (5.8 to 7.0), allophycocyanin aggregates have a sedimentation coefficient of 4.8 (≃α3β3) and an additional absorption peak at 640 nm appears while that at 620 nm remains unaffected. The fluorescence emission maximum of the larger aggregate is at 667 nm and the light-induced change in its absorption is shifted to 650 nm. The effect of pH changes in the range 4.0 to 7.0 on the spectral and aggregation properties of allophycocyanin is completely reversible. Changes in pH which affect allophycocyanin aggregation have parallel effects on absorption and fluorescence maxima as well as on the light-induced absorbance changes of the biliprotein. No evidence is provided to resolve whether this phycochrome plays the role of an adaptochrome. PMID:16661143

Interacting Effects of pH, Temperature, and Salt Concentration on Growth and Survival of Vibrio parahaemolyticus

PubMed Central

Beuchat, L. R.

1973-01-01

Thermal resistance and minimal pH and temperature conditions for growth of Vibrio parahaemolyticus in artificial media containing 3 and 7% sodium chloride were studied. Growth was observed at pH 4.8 and at 5 C. PMID:4715562

Study of human serum albumin structure by dynamic light scattering: two types of reactions under different pH and interaction with physiologically active compounds

NASA Astrophysics Data System (ADS)

Luik, A. I.; Naboka, Yu. N.; Mogilevich, S. E.; Hushcha, T. O.; Mischenko, N. I.

1998-09-01

The effect of pH and binding of ten physiologically active compounds (isoproterenol, yohimbine, propranolol, clonidine, phenylephrine, carbachol, tripeptide fMLP, diphenhydramine, chlorpromazine and atropine) on the molecular structure of human serum albumin (HSA) has been studied using the dynamic light scattering. It was found that albumin globule has the most compact configuration (Stokes diameter 59-62 Å) at physiological pH 7.4. The changes in pH, both increase to 8.0 and decrease to 5.4, result in the growth of globule size to 72-81 Å. At acidic shift of pH an additional peak arises in the correlation spectra caused by the light scattering on the structures with the Stokes diameters of 29-37 Å. Those conform to the sizes of the albumin subdomains. The indicated peak is not displayed at basic shift of pH. The interaction with propranolol, clonidine, phenylephrine, carbachol and tripeptide fMLP which hinder adenylate cyclase (AdC) and activate Ca-polyphosphoinositide (Ca-PPI) signaling system of a cell initiates structural rearrangements similar to acidic transitions. Isoproterenol, yohimbine diphenhydramine, chlorpromazine and atropine, which activate AdC and hinder Ca-PPI, cause conformational changes of HSA similar to basic transitions.

Effect of Storage Temperature on Structure and Function of Cultured Human Oral Keratinocytes

PubMed Central

Islam, Rakibul; Jackson, Catherine; Eidet, Jon R.; Messelt, Edward B.; Corraya, Rima Maria; Lyberg, Torstein; Griffith, May; Dartt, Darlene A.; Utheim, Tor P.

2015-01-01

Purpose/Aims To assess the effect of storage temperature on the viability, phenotype, metabolism, and morphology of cultured human oral keratinocytes (HOK). Materials and Methods Cultured HOK cells were stored in HEPES- and sodium bicarbonate-buffered Minimum Essential Medium (MEM) at nine temperatures in approximately 4°C increments from 4°C to 37°C for seven days. Cells were characterized for viability by calcein fluorescence, phenotype retention by immunocytochemistry, metabolic parameters (pH, glucose, lactate, and O2) within the storage medium by blood gas analysis, and morphology by scanning electron microscopy and light microscopy. Results Relative to the cultured, but non-stored control cells, a high percentage of viable cells were retained only in the 12°C and 16°C storage groups (85%±13% and 68%±10%, respectively). Expression of ABCG2, Bmi1, C/EBPδ, PCNA, cytokeratin 18, and caspase-3 were preserved after storage in the 5 groups between 4°C and 20°C, compared to the non-stored control. Glucose, pH and pO2 in the storage medium declined, whereas lactate increased with increasing storage temperature. Morphology was best preserved following storage of the three groups between 12°C, 16°C, and 20°C. Conclusion We conclude that storage temperatures of 12°C and 16°C were optimal for maintenance of cell viability, phenotype, and morphology of cultured HOK. The storage method described in the present study may be applicable for other cell types and tissues; thus its significance may extend beyond HOK and the field of ophthalmology. PMID:26052937

Macroalgal response to a warmer ocean with higher CO2 concentration.

PubMed

Hernández, Celso A; Sangil, Carlos; Fanai, Alessandra; Hernández, José Carlos

2018-05-01

Primary production and respiration rates were studied for six seaweed species (Cystoseira abies-marina, Lobophora variegata, Pterocladiella capillacea, Canistrocarpus cervicornis, Padina pavonica and Corallina caespitosa) from Subtropical North-East Atlantic, to estimate the combined effects of different pH and temperature levels. Macroalgal samples were cultured at temperature and pH combinations ranging from current levels to those predicted for the next century (19, 21, 23, 25 °C, pH: 8.1, 7.7 and 7.4). Decreased pH had a positive effect on short-term production of the studied species. Raised temperatures had a more varied and species dependent effect on short term primary production. Thermophilic algae increased their production at higher temperatures, while temperate species were more productive at lower or present temperature conditions. Temperature also affected algal respiration rates, which were higher at low temperature levels. The results suggest that biomass and productivity of the more tropical species in coastal ecosystems would be enhanced by future ocean conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Post-deposition annealing temperature dependence TiO{sub 2}-based EGFET pH sensor sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zulkefle, M. A., E-mail: alhadizulkefle@gmail.com; Rahman, R. A., E-mail: rohanieza.abdrahman@gmail.com; Yusoff, K. A., E-mail: khairul.aimi.yusof@gmail.com

EGFET pH sensor is one type of pH sensor that is used to measure and determine pH of a solution. The sensing membrane of EGFET pH sensor plays vital role in the overall performance of the sensor. This paper studies the effects of different annealing temperature of the TiO{sub 2} sensing membranes towards sensitivity of EGFET pH sensor. Sol-gel spin coating was chosen as TiO{sub 2} deposition techniques since it is cost-effective and produces thin film with uniform thickness. Deposited TiO{sub 2} thin films were then annealed at different annealing temperatures and then were connected to the gate of MOSFETmore » as a part of the EGFET pH sensor structure. The thin films now act as sensing membranes of the EGFET pH sensor and sensitivity of each sensing membrane towards pH was measured. From the results it was determined that sensing membrane annealed at 300 °C gave the highest sensitivity followed by sample annealed at 400 °C and 500 °C.« less

Rheological behavior and Ibuprofen delivery applications of pH responsive composite alginate hydrogels.

PubMed

Jabeen, Suraya; Maswal, Masrat; Chat, Oyais Ahmad; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

2016-03-01

Synthesis and structural characterization of hydrogels composed of sodium alginate, polyethylene oxide and acrylic acid with cyclodextrin as the hydrocolloid prepared at different pH values is presented. The hydrogels synthesized show significant variations in rheological properties, drug encapsulation capability and release kinetics. The hydrogels prepared at lower pH (pH 1) are more elastic, have high tensile strength and remain almost unaffected by varying temperature or frequency. Further, their Ibuprofen encapsulation capacity is low and releases it slowly. The hydrogel prepared at neutral pH (pH 7) is viscoelastic, thermo-reversible and also exhibits sol-gel transition on applying frequency and changing temperature. It shows highest Ibuprofen encapsulation capacity and also optimum drug release kinetics. The hydrogel prepared at higher pH (pH 12) is more viscous, has low tensile strength, is unstable to change in temperature and has fast drug release rate. The study highlights the pH responsiveness of three composite alginate hydrogels prepared under different conditions to be employed in drug delivery applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermophysical properties of carboxylic and amino acid buffers at subzero temperatures: relevance to frozen state stabilization.

PubMed

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-06-02

Macromolecules and other thermolabile biologicals are often buffered and stored in frozen or dried (freeze-dried) state. Crystallization of buffer components in frozen aqueous solutions and the consequent pH shifts were studied in carboxylic (succinic, malic, citric, tartaric acid) and amino acid (glycine, histidine) buffers. Aqueous buffer solutions were cooled from room temperature (RT) to -25 °C and the pH of the solution was measured as a function of temperature. The thermal behavior of frozen solutions was investigated by differential scanning calorimetry (DSC), and the crystallized phases were identified by X-ray diffractometry (XRD). Based on the solubility of the neutral species of each buffer system over a range of temperatures, it was possible to estimate its degree of supersaturation at the subambient temperature of interest. This enabled us to predict its crystallization propensity in frozen systems. The experimental and the predicted rank orderings were in excellent agreement. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartrate systems, at initial pH < pK(a)(2), only the most acidic buffer component (neutral form) crystallized on cooling, causing an increase in the freeze-concentrate pH. In glycine buffer solutions, when the initial pH was ∼3 units < isoelectric pH (pI = 5.9), β-glycine crystallization caused a small decrease in pH, while a similar effect but in the opposite direction was observed when the initial pH was ∼3 units > pI. In the histidine buffer system, depending on the initial pH, either histidine or histidine HCl crystallized.

Diurnal variation of intraoral pH and temperature.

PubMed

Choi, Jung Eun; Lyons, Karl M; Kieser, Jules A; Waddell, Neil J

2017-01-01

The aim of this study was to measure continuously the intraoral pH and temperature of healthy individuals to investigate their diurnal variations. Seventeen participants (mean age, 31±9 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for two sets of 24 h, while carrying out normal daily activities including sleep. The continuous changes in intraoral pH and temperature were captured using a sensor placed on the palatal aspect of the upper central incisors. The collected data were categorised into different status (awake and sleep) and periods (morning, afternoon, evening and night). Both quantitative and qualitative analyses were conducted. The intraoral pH change was found to show a distinctive daily rhythm, showing a 12-h interval between maximum (7.73) and minimum (6.6) pH values. The maximum and minimum values were found to repeat after 24 h. The mean pH over 48 h (two sets of 24 h) was found to be 7.27 (±0.74). There was significant difference found in pH when subjects were awake and asleep and different periods during the day ( P <0.001). The mean intraoral temperature was 33.99 °C (±4.9), with less distinctive daily rhythm compared with pH. There was a significant difference found in temperature depending on the time of the day, except between morning and afternoon ( P =0.78). Our results showed that there is a distinctive daily, circadian-like pattern in intraoral pH variation over a 24-h period, which has been considered as one of the risk factors in sleep-related dental diseases.

Enhancing the auto-flocculation of photosynthetic bacteria to realize biomass recovery in brewery wastewater treatment.

PubMed

Lu, Haifeng; Dong, Shan; Zhang, Guangming; Han, Ting; Zhang, Yuanhui; Li, Baoming

2018-02-15

Photosynthetic bacteria (PSB) wastewater treatment technology can simultaneously realize wastewater purification and biomass production. The produced biomass contains high value-added products, which can be used in medical and agricultural industry. However, because of the small size and high electronegativity, PSB are hard to be collected from wastewater, which hampers the commercialization of PSB-based industrial processes. Auto-flocculation is a low cost, energy saving, non-toxic biomass collection method for microbiology. In this work, the influence factors with their optimal levels and mechanism for enhancing the auto-flocculation of PSB were investigated in pure cultivation medium. Then PSB auto-flocculation performance in real brewery wastewater was probed. Results showed that Na + concentration, pH and light intensity were three crucial factors except the initial inoculum sizes and temperature. In the pure medium cultivation system, the optimal condition for PSB auto-flocculation was as follows: pH was 9.5, inoculum size was 420 mg l -1 , Na + concentration was 0.067 mol l -1 , light intensity was 5000 lux, temperature was 30°C. Under the optimal condition, the auto-flocculation ratio and biomass recovery reached 85.0% and 1488 mg l -1 , which improved by 1.67-fold and 2.14-fold compared with the PSB enrichment cultivation conditions, respectively. Mechanism analysis showed that the protein/polysaccharides ratio and absolute Zeta potential value had a liner relationship. For the brewery wastewater treatment, under the above optimal condition, the chemical oxygen demand removal reached 94.3% with the auto-flocculation ratio and biomass recovery of 89.6% and 1510 mg l -1 , which increased 2.75-fold and 2.77-fold, respectively.

Degradations of acetaminophen via a K2S2O8-doped TiO2 photocatalyst under visible light irradiation.

PubMed

Lin, Justin Chun-Te; de Luna, Mark Daniel G; Aranzamendez, Graziel L; Lu, Ming-Chun

2016-07-01

Acetaminophen (ACT) is a mild analgesic commonly used for relief of fever, headache and some minor pains. It had been detected in both fixed factory-discharged wastewaters, and diverse sources, e.g. surface waters during festival events. Degradation of such trace emergent pollutants by titanium dioxide (TiO2) photocatalysts is a common approach; however, the band gap that can be utilized in the UV range is limited. In order to extend downward the energy required to excite the photocatalytic material, doping with potassium peroxodisulfate (K2S2O8) by a sol-gel method was done in this work. The visible-light active photocatalyst was tested on the degradation of ACT under four parameters including: initial ACT concentration, catalyst dose, initial pH, and system temperature. Optimal conditions, which achieved 100% ACT degradation, were obtained by using 0.1 mM ACT initial concentration, catalyst dose of 1 g L(-1), initial pH of 9.0 and system temperature of 22 °C at the end of 9-h irradiation. Meanwhile, three types of degradation kinetic models (i.e. zero, pseudo first and second order) were tested. The feasible model followed a pseudo-first order model with the computed constant (kapp) of 7.29 × 10(-3) min(-1). The present study provides a better photocatalytic degradation route by K2S2O8-modified TiO2 in comparison with pristine TiO2, in wastewater treatment dealing with ACT and other persistent organic pollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigation of pH and temperature on optical rotatory dispersion for noninvasive glucose monitoring

NASA Astrophysics Data System (ADS)

Baba, Justin S.; Meledeo, Adam; Cameron, B. D.; Cote, Gerard L.

2001-06-01

The widespread occurrence of diabetes mellitus and the severity of its associated complications necessitate the development of non-invasive blood glucose measurement devices in an attempt to improve treatment regimens and curb the complications associated with this disease. One method showing promise in this endeavor utilizes optical polarimetry to monitor blood glucose levels indirectly by measuring glucose rotation of polarized light, which is a direct indication of glucose concentration, in the aqueous humor of the eye. The presence of other optically active (chiral) components in the aqueous humor of the eye have the potential to confound the glucose measurement of optical rotation when using a single wavelength polarimeter. Thus, this has led to the recent investigation of multispectral polarimetric systems which have the potential to enable the removal of confounder contributions to the net observed optical rotation, therefore, increasing glucose specificity and reducing glucose prediction errors. Such polarimetric systems take advantage of the uniqueness in the rotation of polarized light, as a function of wavelength, by the chiral molecule of interest. This is commonly referred to as the optical rotatory dispersion (ORD) spectra of the chiral molecule. ORD characterization of the chiral molecules within the aqueous humor is necessary for determining the optimum number of wavelengths needed to reduce glucose prediction errors; however, this information is often only given at the sodium-D line (589 nm) in the literature. This report describes the system we designed and built to measure ORD spectra for glucose and for albumin, the main optical confounder within the aqueous humor, as well as our investigation of the effects of temperature and pH on these ORD spectra.

Effects of elevated pCO2 on physiological performance of marine microalgae Dunaliella salina (Chlorophyta, Chlorophyceae

NASA Astrophysics Data System (ADS)

Hu, Shunxin; Wang, You; Wang, Ying; Zhao, Yan; Zhang, Xinxin; Zhang, Yongsheng; Jiang, Ming; Tang, Xuexi

2018-03-01

The present study was conducted to determine the effects of elevated pCO2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga Dunaliella salina. To accomplish this, D. salina was incubated in semi-continuous cultures under present-day CO2 levels (390 μatm, pHNBS: 8.10), predicted year 2100 CO2 levels (1 000 μatm, pHNBS: 7.78) and predicted year 2300 CO2 levels (2 000 μatm, pHNBS: 7.49). Elevated pCO2 significantly enhanced photosynthesis (in terms of gross photosynthetic O2 evolution, effective quantum yield (Δ F/ F' m ), photosynthetic efficiency ( α), maximum relative electron transport rate (rETRmax) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity) and dark respiration of D. salina, but had insignificant effects on growth. The photosynthetic O2 evolution of D. salina was significantly inhibited by the inhibitors acetazolamide (AZ), ethoxyzolamide (EZ) and 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS), indicating that D. salina is capable of acquiring HCOˉ 3 via extracellular carbonic anhydrase and anion-exchange proteins. Furthermore, the lower inhibition of the photosynthetic O2 evolution at high pCO2 levels by AZ, EZ and DIDS and the decreased carbonic anhydrase showed that carbon concentrating mechanisms were down-regulated at high pCO2. In conclusion, our results show that photosynthesis, dark respiration and CCMs will be affected by the increased pCO2/low pH conditions predicted for the future, but that the responses of D. salina to high pCO2/low pH might be modulated by other environmental factors such as light, nutrients and temperature. Therefore, further studies are needed to determine the interactive effects of pCO2, temperature, light and nutrients on marine microalgae.

Effects of elevated pCO2 on physiological performance of marine microalgae Dunaliella salina (Chlorophyta, Chlorophyceae)

NASA Astrophysics Data System (ADS)

Hu, Shunxin; Wang, You; Wang, Ying; Zhao, Yan; Zhang, Xinxin; Zhang, Yongsheng; Jiang, Ming; Tang, Xuexi

2017-06-01

The present study was conducted to determine the effects of elevated pCO2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga Dunaliella salina. To accomplish this, D. salina was incubated in semi-continuous cultures under present-day CO2 levels (390 μatm, pHNBS: 8.10), predicted year 2100 CO2 levels (1 000 μatm, pHNBS: 7.78) and predicted year 2300 CO2 levels (2 000 μatm, pHNBS: 7.49). Elevated pCO2 significantly enhanced photosynthesis (in terms of gross photosynthetic O2 evolution, effective quantum yield (ΔF/F' m ), photosynthetic efficiency (α), maximum relative electron transport rate (rETRmax) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity) and dark respiration of D. salina, but had insignificant effects on growth. The photosynthetic O2 evolution of D. salina was significantly inhibited by the inhibitors acetazolamide (AZ), ethoxyzolamide (EZ) and 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS), indicating that D. salina is capable of acquiring HCO3 - via extracellular carbonic anhydrase and anion-exchange proteins. Furthermore, the lower inhibition of the photosynthetic O2 evolution at high pCO2 levels by AZ, EZ and DIDS and the decreased carbonic anhydrase showed that carbon concentrating mechanisms were down-regulated at high pCO2. In conclusion, our results show that photosynthesis, dark respiration and CCMs will be affected by the increased pCO2/low pH conditions predicted for the future, but that the responses of D. salina to high pCO2/low pH might be modulated by other environmental factors such as light, nutrients and temperature. Therefore, further studies are needed to determine the interactive effects of pCO2, temperature, light and nutrients on marine microalgae.

Biodiesel production from algae grown on food industry wastewater.

PubMed

Mureed, Khadija; Kanwal, Shamsa; Hussain, Azhar; Noureen, Shamaila; Hussain, Sabir; Ahmad, Shakeel; Ahmad, Maqshoof; Waqas, Rashid

2018-04-10

Algae have an ample potential to produce biodiesel from spent wash of food industry. In addition, it is cheaper and presents an environment friendly way to handle food industry wastewater. This study was conducted to optimize the growth of microalgal strains and to assess biodiesel production potential of algae using untreated food industry wastewater as a source of nutrients. The food industry wastewater was collected and analyzed for its physicochemical characteristics. Different dilutions (10, 20, 40, 80, and 100%) of this wastewater were made with distilled water, and growth of two microalgal strains (Cladophora sp. and Spyrogyra sp.) was recorded. Each type of wastewater was inoculated with microalgae, and biomass was harvested after 7 days. The growth of both strains was also evaluated at varying temperatures, pH and light periods to optimize the algal growth for enhanced biodiesel production. After optimization, biodiesel production by Spyrogyra sp. was recorded in real food industry wastewater. The algal biomass increased with increasing level of food industry wastewater and was at maximum with 100% wastewater. Moreover, statistically similar results were found with algal growth on 100% wastewater and also on Bristol's media. The Cladophora sp. produced higher biomass than Spyrogyra sp. while growing on food industry wastewater. The optimal growth of both microalgal strains was observed at temperature 30 °C, pH: 8, light 24 h. Cladophora sp. was further evaluated for biodiesel production while growing on 100% wastewater and found that this strain produced high level of oil and biodiesel. Algae have an ample potential to produce biodiesel from spent wash of food industry. In addition, it is cheaper and presents an environment friendly way to handle food industry wastewater.

The effect of environmental and physiological conditions on excystation of Acanthamoeba castellanii belonging to the T4 genotype.

PubMed

Lakhundi, Sahreena; Khan, Naveed Ahmed; Siddiqui, Ruqaiyyah

2014-08-01

Excystation in Acanthamoeba is an important property for the onset of infection as well as infection recurrence, post-treatment. The overall aim of this study was to determine the effects of several environmental and physiological parameters on excystation in Acanthamoeba castellanii belonging to the T4 genotype. Cysts were prepared by inoculating A. castellanii trophozoites on non-nutrient agar plates for up to 2 weeks. To determine the effects of various conditions on excystation, A. castellanii cysts were inoculated in growth medium i.e. PYG and incubated at varying temperatures (4-40 °C), various pHs (4-9), artificial light/dark cycles and 5% of CO2. Optimum excystation was observed when cysts were incubated at 30 °C in growth medium at neutral pH. Extremes of temperature and pH reduced excystation, while light/dark cycles had no effect on excystation of A. castellanii. On the other hand, 5% of CO2 enhanced excystation and growth of excysting amoebae. To determine the effect of serum on A. castellanii excystation, assays were performed in the presence of varying concentrations of heat-inactivated foetal bovine serum (FBS) (5-100%). The results revealed that FBS promoted excystation. The involvement of G proteins in excystation was also determined. Using propranolol hydrochloride, a G protein inhibitor, the results revealed that G proteins play a role in A. castellanii differentiation. Furthermore, organic solvents (methanol/ethanol) completely blocked excystation. None of the aforementioned conditions had any effect on the viability of A. castellanii. A complete understanding of excystation in A. castellanii will be of value to counter infection recurrence.

Investigation of pH and Temperature Profiles in the GI Tract of Fasted Human Subjects Using the Intellicap(®) System.

PubMed

Koziolek, Mirko; Grimm, Michael; Becker, Dieter; Iordanov, Ventzeslav; Zou, Hans; Shimizu, Jeff; Wanke, Christoph; Garbacz, Grzegorz; Weitschies, Werner

2015-09-01

Gastrointestinal (GI) pH and temperature profiles under fasted-state conditions were investigated in two studies with each 10 healthy human subjects using the IntelliCap(®) system. This telemetric drug delivery device enabled the determination of gastric emptying time, small bowel transit time, and colon arrival time by significant pH and temperature changes. The study results revealed high variability of GI pH and transit times. The gastric transit of IntelliCap(®) was characterized by high fluctuations of the pH with mean values ranging from pH 1.7 to pH 4.7. Gastric emptying was observed after 7-202 min (median: 30 min). During small bowel transit, which had a duration of 67-532 min (median: 247 min), pH values increased slightly from pH 5.9-6.3 in proximal parts to pH 7.4-7.8 in distal parts. Colonic pH conditions were characterized by values fluctuating mainly between pH 5 and pH 8. The pH profiles and transit times described in this work are highly relevant for the comprehension of drug delivery of solid oral dosage forms comprising ionizable drugs and excipients with pH-dependent solubility. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

An investigation of the stability of free and glucuronidated 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid in authentic urine samples.

PubMed

Skopp, Gisela; Pötsch, Lucia

2004-01-01

Preanalytical stability of a drug and its major metabolites is an important consideration in pharmacokinetic studies or whenever the analyte pattern is used to estimate drug habits. Firstly, the stability of free and glucuronidated 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH, THCCOOglu) in authentic urine samples was investigated. Random urine samples of cannabis users (n = 38) were stored at -20, 4, and 20 degrees C up to 15 days and up to 5 days at 40 degrees C, and alterations of the analyte pattern during storage were followed by liquid chromatography-tandem mass spectrometry. Secondly, the influence of pH (range 5.0-8.0) on the stability of the analytes was studied using spiked urine to elucidate the results obtained from authentic samples. In authentic urine samples, the initial pH ranged from 5.1 to 8.8. The glucuronide was found to be highly labile at a storage temperature of 4 degrees C and above. Initially, 18 urine samples tested positive for THCCOOH. After 2 days storage at 20 degrees C, THCCOOH was detectable in a further 4 samples, and 7 more samples tested positive for THCCOOH (5-81 ng/mL) after 15 days. Depending on time and temperature, the glucuronide concentration decreased, resulting in an increase of THCCOOH concentration. However, a loss in mean total THCCOOH concentration was found, which was significantly higher in deteriorated samples than in samples without signs of deterioration after 15 days of storage at 20 degrees C. In the drug-free urine sample separately spiked with THCCOOglu or THCCOOH, the investigations on the stability of the target analytes at various pH values revealed that THCCOOH was stable at pH 5.0. At higher pH values, its concentration slightly decreased with time, and about 69% of the initial THCCOOH concentration was still present at pH 8.0 on day 5. THCCOOglu concentrations rapidly decreased with increasing pH value. For example, only 72% of the initial THCCOOglu concentration could be detected at pH 5.0 on day 1. Degradation of the glucuronide resulted in formation of THCCOOH, which was observed even at pH 5.0. In light of the present findings, advanced forensic interpretations based on the presence of THCCOOH or the pattern of THCCOOH and THCCOOglu in stored urine samples seems questionable.

Kinetics and mechanism of imazosulfuron hydrolysis.

PubMed

Morrica, P; Barbato, F; Della Iacovo, R; Seccia, S; Ungaro, F

2001-08-01

Knowledge of the kinetics and pathways of hydrolytic degradation is crucial to the prediction of the fate and transport mechanism of chemicals. This work first describes the kinetics of the chemical hydrolysis of imazosulfuron, a new sulfonylurea herbicide, and evaluates the results to propose a degradation pathway. The hydrolysis of imazosulfuron has been studied in aqueous buffers both within the pH range 1.9-12.3 at ambient temperature (thermostated at 25 +/- 2 degrees C) and at pH 3.6 within the temperature range of 15-55 degrees C. The hydrolysis rate of imazosulfuron was characterized by a first-order kinetics, pH- and temperature-dependent, and accelerated by acidic conditions and higher temperatures. The calculated half-lives at pH 4.5 and 5.9 were 36.5 and 578 days, respectively. At pH 6.6, 7.4, 9.2, and 12.3 no significant change in imazosulfuron concentration was observed after 150 days. Half-lives were much lower at pH <4 (= imazosulfuron pK(a)), at which they ranged from 3.3 to 6.3 days. Moreover, a change in temperature from 15 to 25 degrees C in acidic conditions (pH 3.6) decreased the half-life of imazosulfuron by a factor of approximately 4.0; in any case, a 3-5-fold increase in the rate of hydrolysis was found for each 10 degrees C increase in temperature. In acidic conditions the only hydrolysis products were the two molecules resulting from the cleavage of the sulfonylurea bridge.

Modeling of thermal degradation kinetics of the C-glucosyl xanthone mangiferin in an aqueous model solution as a function of pH and temperature and protective effect of honeybush extract matrix.

PubMed

Beelders, Theresa; de Beer, Dalene; Kidd, Martin; Joubert, Elizabeth

2018-01-01

Mangiferin, a C-glucosyl xanthone, abundant in mango and honeybush, is increasingly targeted for its bioactive properties and thus to enhance functional properties of food. The thermal degradation kinetics of mangiferin at pH3, 4, 5, 6 and 7 were each modeled at five temperatures ranging between 60 and 140°C. First-order reaction models were fitted to the data using non-linear regression to determine the reaction rate constant at each pH-temperature combination. The reaction rate constant increased with increasing temperature and pH. Comparison of the reaction rate constants at 100°C revealed an exponential relationship between the reaction rate constant and pH. The data for each pH were also modeled with the Arrhenius equation using non-linear and linear regression to determine the activation energy and pre-exponential factor. Activation energies decreased slightly with increasing pH. Finally, a multi-linear model taking into account both temperature and pH was developed for mangiferin degradation. Sterilization (121°C for 4min) of honeybush extracts dissolved at pH4, 5 and 7 did not cause noticeable degradation of mangiferin, although the multi-linear model predicted 34% degradation at pH7. The extract matrix is postulated to exert a protective effect as changes in potential precursor content could not fully explain the stability of mangiferin. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temperature and oxygen-concentration dependence of singlet oxygen production by RuPhen as induced by quasi-continuous excitation.

PubMed

Varchola, Jaroslav; Huntosova, Veronika; Jancura, Daniel; Wagnières, Georges; Miskovsky, Pavol; Bánó, Gregor

2014-12-01

Assessment of partial pressure of oxygen (pO2) by luminescence lifetime measurements of ruthenium coordination complexes has been studied intensively during the last few decades. RuPhen (dichlorotris(1,10-phenanthroline) ruthenium(ii) hydrate) is a water soluble molecule that has been tested previously for in vivo pO2 detection. In this work we intended to shed light on the production of singlet oxygen by RuPhen. The quantum yield of singlet oxygen production by RuPhen dissolved in 0.9% aqueous NaCl solution (pH = 6) was measured at physiological temperatures (285-310 K) and various concentrations of molecular oxygen. In order to minimize the bleaching of RuPhen, the samples were excited with low power (<2 mW) laser pulses (20 μs long), created by pulsing a cw laser beam with an acousto-optical modulator. We show that, whereas the RuPhen phosphorescence lifetime decreases rapidly with an increase of temperature (keeping the oxygenation level constant), the quantum yield of singlet oxygen production by RuPhen is almost identical in the temperature range of 285-310 K. For air-saturated conditions at 310 K the measured quantum yield is about 0.25. The depopulation rate constants of the RuPhen (3)MLCT (metal-to-ligand charge-transfer) state are determined in the absence and in the presence of oxygen. We determined that the excitation energy for the RuPhen (3)MLCT→d-d transition is 49 kJ mol(-1) in the 0.9% NaCl solution (pH = 6).

An EPR study of the pH dependence of formate effects on Photosystem II.

PubMed

Jajoo, Anjana; Katsuta, Nobuhiro; Kawamori, Asako

2006-04-01

Effects of formate on rates of O(2) evolution and electron paramagnetic resonance (EPR) signals were observed in the oxygen evolving PS II membranes as a function of pH. In formate treated PS II membranes, decrease in pH value resulted in the inhibition of the O(2) evolving activity, a decrease in the intensity of S(2) state multiline signal but an increase in the intensity of the Q(A)(-)Fe(2+) EPR signal. Time-resolved EPR study of the Y(Z)(*) decay kinetics showed that the light-induced intensity of Y(Z)(*) EPR signal was proportional to the formate concentration. The change in the pH affected both the light-induced intensities and the decay rates of Y(Z)(*), which was found to be faster at lower pH. At 253 K, t(1/e) value of Y(Z)(*) decay kinetics was found to be 8-10 s at pH 6.0 and 18-21 s at pH 5.0. The results presented here indicate that the extent of inhibition at the donor and the acceptor side of PS II due to formate is pH dependent, being more effective at lower pH.

A dual pH and temperature responsive polymeric fluorescent sensor and its imaging application in living cells.

PubMed

Yin, Liyan; He, Chunsheng; Huang, Chusen; Zhu, Weiping; Wang, Xin; Xu, Yufang; Qian, Xuhong

2012-05-11

A polymeric fluorescent sensor PNME, consisting of A4 and N-isopropylacrylamide (NIPAM) units, was synthesized. PNME exhibited dual responses to pH and temperature, and could be used as an intracellular pH sensor for lysosomes imaging. Moreover, it also could sense different temperature change in living cells at 25 and 37 °C, respectively. This journal is © The Royal Society of Chemistry 2012

Zinc oxide-mediated photocatalytic decolorization of Ponceau S in aqueous suspension by visible light

NASA Astrophysics Data System (ADS)

Muslim, Muhammad; Habib, Md Ahsan; Mahmood, Abu Jafar; Islam, Tajmeri Selima Akhter; Ismail, Iqbal Mohmmad Ibrahim

2012-10-01

ZnO, comprising nanosize particles (approximately 40 nm) has been prepared by heating (300°C) ZnCO3, which was obtained as precipitate by mixing ZnSO4 and (NH4)2CO3 solutions. The prepared ZnO was characterized by X-ray diffraction, scanning electron microscopy (SEM), laser-induced breakdown spectroscopy, and adsorption studies. It has been used to catalyze the decolorization of Ponceau S (PS), a model diazo dye, in an aqueous suspension under visible light ( I ≈ 1.8 × 10-4 W cm-2). This ZnO was found to be more efficient as a photocatalyst compared to pristine ZnO. ZnO samples with higher temperatures (500°C and 700°C) show less catalytic activity. SEM images show that the particle size of ZnO increases with the increase in calcined temperature of ZnO through agglomeration, resulting in a decrease in surface area. Photodecolorization of PS is affected by its and ZnO concentrations, but unaffected by the initial pH of the solutions in the range of 4 to 7. Illumination for a sufficiently long time completely mineralizes the dye, but no Zn2+ can be detected in the clear solution. Photodegradation kinetics in the ZnO suspension obeys the Langmuir-Hinshelwood equation, and some activation of the ZnO surface by light is indicated.

Effect of temperature and pH on polygalacturonase production by pectinolytic bacteria Bacillus licheniformis strain GD2a in submerged medium from Raja Nangka (Musa paradisiaca var. formatypica) banana peel waste

NASA Astrophysics Data System (ADS)

Widowati, E.; Utami, R.; Mahadjoeno, E.; Saputro, G. P.

2017-04-01

The aim of this research were to determine the effect of temperature (45°C, 55°C, 65°C) and pH (5.0; 6.0; 7.0) on the increase of total cell count and polygalacturonase enzyme activity produced from raja nangka banana (Musa paradisiaca var. formatypica) peel waste by pectinolytic bacterial Bacillus licheniformis strain GD2a. This research applied two sample repetition and one analysis repetition. The result showed temperature and pH affect total cell count. The total cell count on 45°C and pH 7 recorded the highest number at 9.469 log cell/ml. Temperature and pH also affected pectin concentration at the end of fermentation. The lowest pectin concentration recorded at 45°C and pH 7 was 0.425 %. The highest enzyme activity recorded at 65°C and pH 7 was 0.204 U/ml. The highest enzyme protein concentration was recorded at 65°C and resulted as 0.310 mg/ml on pH 6. The highest specific activity was 19.527 U/mg at 65°C and pH 7. By this result, could be concluded that optimum condition process on polygalacturonase production was at 65°C and pH 7 because it gave highest enzyme activity result (0,204 U/ml).

Humboldt's spa: microbial diversity is controlled by temperature in geothermal environments.

PubMed

Sharp, Christine E; Brady, Allyson L; Sharp, Glen H; Grasby, Stephen E; Stott, Matthew B; Dunfield, Peter F

2014-06-01

Over 200 years ago Alexander von Humboldt (1808) observed that plant and animal diversity peaks at tropical latitudes and decreases toward the poles, a trend he attributed to more favorable temperatures in the tropics. Studies to date suggest that this temperature-diversity gradient is weak or nonexistent for Bacteria and Archaea. To test the impacts of temperature as well as pH on bacterial and archaeal diversity, we performed pyrotag sequencing of 16S rRNA genes retrieved from 165 soil, sediment and biomat samples of 36 geothermal areas in Canada and New Zealand, covering a temperature range of 7.5-99 °C and a pH range of 1.8-9.0. This represents the widest ranges of temperature and pH yet examined in a single microbial diversity study. Species richness and diversity indices were strongly correlated to temperature, with R(2) values up to 0.62 for neutral-alkaline springs. The distributions were unimodal, with peak diversity at 24 °C and decreasing diversity at higher and lower temperature extremes. There was also a significant pH effect on diversity; however, in contrast to previous studies of soil microbial diversity, pH explained less of the variability (13-20%) than temperature in the geothermal samples. No correlation was observed between diversity values and latitude from the equator, and we therefore infer a direct temperature effect in our data set. These results demonstrate that temperature exerts a strong control on microbial diversity when considered over most of the temperature range within which life is possible.

Effect of pH and temperature on the stability of UV-induced repairable pyrimidine hydrates in DNA.

PubMed

O'Donnell, R E; Boorstein, R J; Cunningham, R P; Teebor, G W

1994-08-23

UV irradiation of cytosine yields 6-hydroxy-5,6-dihydrocytosine (cytosine hydrate) whether the cytosine is in solution as base, nucleoside, or nucleotide or on the DNA backbone. Cytosine hydrate decomposes by elimination of water, yielding cytosine, or by irreversible deamination, yielding uracil hydrate, which, in turn, decomposes by dehydration yielding uracil. To determine how pH and temperature affect these decomposition reactions, alternating poly(dG-[3H]dC) copolymer was irradiated at 254 nm and incubated under different conditions of pH and temperature. The cytosine hydrate and uracil hydrate content of the DNA was determined by the use of Escherichia coli endonuclease III, which releases pyrimidine hydrates from DNA by virtue of its DNA glycosylase activity. Uracil content was determined by using uracil-DNA glycosylase. The rate of decomposition of cytosine hydrate to cytosine was determined at 4 temperatures at pH 3.1, 5.4, and 7.4. The Ea was determined from the rates by using the Arrhenius equation and proved to be the same at pH 5.4 and 7.4, although the decomposition rate at pH 5.4 was faster at all temperatures. At pH 3.1, the Ea was reduced. These results suggest that the dehydration reaction is affected by two discrete protonations, most probably of the N-3 and the OH group of C-6 of cytosine hydrate. The deamination of cytosine hydrate to uracil hydrate was maximal at pH 3.1 at all temperatures. The doubly protonated cytosine hydrate probably is the common intermediate for both competing decomposition reactions, explaining why cytosine hydrate is prone to deamination at acid pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of Serratia marcescens ompF and ompC porin genes in response to osmotic stress, salicylate, temperature and pH.

PubMed

Begic, Sanela; Worobec, Elizabeth A

2006-02-01

Serratia marcescens is a Gram-negative enterobacterium that has become an important opportunistic pathogen, largely due to its high degree of natural antibiotic resistance. One factor contributing to this natural antibiotic resistance is reduced outer membrane permeability, which is controlled in part by OmpC and OmpF porin proteins. OmpF expression is regulated by micF, an RNA transcript encoded upstream of the ompC gene, which hybridizes with the ompF transcript to inhibit its translation. Regulation of S. marcescens porin gene expression, as well as that of micF, was investigated using beta-galactosidase reporter gene fusions in response to 5, 8 and 10 % sucrose, 1, 5 and 8 mM salicylate, and different pH and temperature values. beta-Galactosidase activity assays revealed that a lower growth temperature (28 degrees C), a more basic pH (pH 8), and an absence of sucrose and salicylate induce the transcription of the ompF gene, whereas the induction of ompC is stimulated at a higher growth temperature (42 degrees C), acidic pH (pH 6), and maximum concentrations of sucrose (10 %) and salicylate (8 mM). In addition, when multiple conditions were tested, temperature had the predominant effect, followed by pH. In this study, it was found that the MicF regulatory mechanism does not play a role in the osmoregulation of the ompF and ompC genes, whereas MicF does repress OmpF expression in the presence of salicylate and high growth temperature, and under low pH conditions.

Rapid Surface Functionalization of Hydrogen-Terminated Silicon by Alkyl Silanols.

PubMed

Escorihuela, Jorge; Zuilhof, Han

2017-04-26

Surface functionalization of inorganic semiconductor substrates, particularly silicon, has focused attention toward many technologically important applications, involving photovoltaic energy, biosensing and catalysis. For such modification processes, oxide-free (H-terminated) silicon surfaces are highly required, and different chemical approaches have been described in the past decades. However, their reactivity is often poor, requiring long reaction times (2-18 h) or the use of UV light (10-30 min). Here, we report a simple and rapid surface functionalization for H-terminated Si(111) surfaces using alkyl silanols. This catalyst-free surface reaction is fast (15 min at room temperature) and can be accelerated with UV light irradiation, reducing the reaction time to 1-2 min. This grafting procedure leads to densely packed organic monolayers that are hydrolytically stable (even up to 30 days at pH 3 or 11) and can display excellent antifouling behavior against a range of organic polymers.

Rapid Surface Functionalization of Hydrogen-Terminated Silicon by Alkyl Silanols

PubMed Central

2017-01-01

Surface functionalization of inorganic semiconductor substrates, particularly silicon, has focused attention toward many technologically important applications, involving photovoltaic energy, biosensing and catalysis. For such modification processes, oxide-free (H-terminated) silicon surfaces are highly required, and different chemical approaches have been described in the past decades. However, their reactivity is often poor, requiring long reaction times (2–18 h) or the use of UV light (10–30 min). Here, we report a simple and rapid surface functionalization for H-terminated Si(111) surfaces using alkyl silanols. This catalyst-free surface reaction is fast (15 min at room temperature) and can be accelerated with UV light irradiation, reducing the reaction time to 1–2 min. This grafting procedure leads to densely packed organic monolayers that are hydrolytically stable (even up to 30 days at pH 3 or 11) and can display excellent antifouling behavior against a range of organic polymers. PMID:28409624

Catalytic degradation of Amlodipine Besylate using ZnO, Cu doped ZnO, and Fe doped ZnO nanoparticles from an aqueous solution: Investigating the effect of different parameters on degradation efficiency

NASA Astrophysics Data System (ADS)

Alizadeh, Elahe; Baseri, Hadi

2018-04-01

Some common nanoparticles, such as Zinc Oxide have been used as nanocatalysts in many processes, but they also have an important application in water purification processes. In this research, ZnO based nanoparticles were used for the degradation of Amlodipine Besylate (AMB) and the effect of some main parameters, e.g. initial concentration of AMB, nanocatalysts dose, pH of the solution, temperature of the solution, H2O2 dose, and the time of visible light irradiation, were investigated. The destruction amount was determined by UV-Vis spectroscopy. The synthesized nanoparticles were characterized by FE-SEM, XRD, FT-IR, BET, BJH, EDS, XRF and UV-Vis techniques. The maximum degradation of AMB was about 90% in 60 min of visible light irradiation with 100 μL of H2O2.

Structural stability of E. coli transketolase to temperature and pH denaturation.

PubMed

Jahromi, Raha R F; Morris, Phattaraporn; Martinez-Torres, Ruben J; Dalby, Paul A

2011-09-10

We have previously shown that the denaturation of TK with urea follows a non-aggregating though irreversible denaturation pathway in which the cofactor binding appears to become altered but without dissociating, then followed at higher urea by partial denaturation of the homodimer prior to any further unfolding or dissociation of the two monomers. Urea is not typically present during biocatalysis, whereas access to TK enzymes that retain activity at increased temperature and extreme pH would be useful for operation under conditions that increase substrate and product stability or solubility. To provide further insight into the underlying causes of its deactivation in process conditions, we have characterised the effects of temperature and pH on the structure, stability, aggregation and activity of Escherichia coli transketolase. The activity of TK was initially found to progressively improve after pre-incubation at increasing temperatures. Loss of activity at higher temperature and low pH resulted primarily from protein denaturation and subsequent irreversible aggregation. By contrast, high pH resulted in the formation of a native-like state that was only partially inactive. The apo-TK enzyme structure content also increased at pH 9 to converge on that of the holo-TK. While cofactor dissociation was previously proposed for high pH deactivation, the observed structural changes in apo-TK but not holo-TK indicate a more complex mechanism. Copyright © 2011 Elsevier B.V. All rights reserved.

Surface sulfonamide modification of poly(N-isopropylacrylamide)-based block copolymer micelles to alter pH and temperature responsive properties for controlled intracellular uptake.

PubMed

Cyphert, Erika L; von Recum, Horst A; Yamato, Masayuki; Nakayama, Masamichi

2018-06-01

Two different surface sulfonamide-functionalized poly(N-isopropylacrylamide)-based polymeric micelles were designed as pH-/temperature-responsive vehicles. Both sulfadimethoxine- and sulfamethazine-surface functionalized micelles were characterized to determine physicochemical properties, hydrodynamic diameters, zeta potentials, temperature-dependent size changes, and lower critical solution temperatures (LCST) in both pH 7.4 and 6.8 solutions (simulating both physiological and mild low pH conditions), and tested in the incorporation of a proof-of-concept hydrophobic antiproliferative drug, paclitaxel. Cellular uptake studies were conducted using bovine carotid endothelial cells and fluorescently labeled micelles to evaluate if there was enhanced cellular uptake of the micelles in a low pH environment. Both variations of micelles showed enhanced intracellular uptake under mildly acidic (pH 6.8) conditions at temperatures slightly above their LCST and minimal uptake at physiological (pH 7.4) conditions. Due to the less negative zeta potential of the sulfamethazine-surface micelles compared to sulfadimethoxine-surface micelles, and the proximity of their LCST to physiological temperature (37°C), the sulfamethazine variation was deemed more amenable for clinically relevant temperature and pH-stimulated applications. Nevertheless, we believe both polymeric micelle variations have the capacity to be implemented as an intracellular drug or gene delivery system in response to mildly acidic conditions. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1552-1560, 2018. © 2018 Wiley Periodicals, Inc.

Stability of Dalteparin 1,000 Unit/mL in 0.9% Sodium Chloride for Injection in Polypropylene Syringes.

PubMed

Kirkham, Kylian; Munson, Jessica M; McCluskey, Susan V; Graner, Kevin K

2017-01-01

The stability of dalteparin 1,000 units/mL in 0.9% sodium chloride for injection stored in polypropylene syringes under refrigeration was examined. Dalteparin 1,000-units/mL syringes were prepared by adding 9 mL of 0.9% sodium chloride for injection to 1 mL of dalteparin sodium 10,000 unit/mL from commercial single-use syringes. Compounded solutions in 0.5-mL aliquots were transferred to 1-mL polypropylene syringes and sealed with a Luer lock tip cap and stored at refrigerated temperatures (2°C to 8°C) with ambient fluorescent light exposure. Syringes from three batches of dalteparin 1,000 units/mL were potency tested in duplicate by a stability-indicating high-performance liquid chromatography assay using a 0.5-mL sample at specified intervals. Visual and pH testing were performed on each batch. Samples were visually inspected for container integrity, color, and clarity. Samples for pH testing were prepared using a 1:1 dilution of dalteparin 1,000 units/mL in sterile water for injection and underwent duplicate analysis at each time point. High-performance liquid chromatography analyses showed a remaining percent of the initial dalteparin content at day 30 of 94.88% ± 2.11%. Samples remained colorless and clear with no signs of container compromise and no visual particulate matter at each time point. Throughout the 30-day study period, pH values remained within 0.3-pH units from the initial value of 5.84. Dalteparin 1,000 unit/mL in 0.9% sodium chloride for injection, packaged in 1-mL polypropylene syringes was stable for at least 30 days while stored at refrigerated conditions with ambient fluorescent light exposure. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Modulators of actin-myosin dissociation: basis for muscle type functional differences during fatigue

PubMed Central

Karatzaferi, Christina; Adamek, Nancy

2017-01-01

The muscle types present with variable fatigue tolerance, in part due to the myosin isoform expressed. However, the critical steps that define “fatigability” in vivo of fast vs. slow myosin isoforms, at the molecular level, are not yet fully understood. We examined the modulation of the ATP-induced myosin subfragment 1 (S1) dissociation from pyrene-actin by inorganic phosphate (Pi), pH, and temperature using a specially modified stopped-flow system that allowed fast kinetics measurements at physiological temperature. We contrasted the properties of rabbit psoas (fast) and bovine masseter (slow) myosins (obtained from samples collected from New Zealand rabbits and from a licensed abattoir, respectively, according to institutional and national ethics permits). To identify ATP cycling biochemical intermediates, we assessed ATP binding to a preequilibrated mixture of actomyosin and variable [ADP], pH (pH 7 vs. pH 6.2), and Pi (zero, 15, or 30 added mM Pi) in a range of temperatures (5 to 45°C). Temperature and pH variations had little, if any, effect on the ADP dissociation constant (KADP) for fast S1, but for slow S1, KADP was weakened with increasing temperature or low pH. In the absence of ADP, the dissociation constant for phosphate (KPi) was weakened with increasing temperature for fast S1. In the presence of ADP, myosin type differences were revealed at the apparent phosphate affinity, depending on pH and temperature. Overall, the newly revealed kinetic differences between myosin types could help explain the in vivo observed muscle type functional differences at rest and during fatigue. PMID:28931538

Temperature Dependent Effects of Elevated CO2 on Shell Composition and Mechanical Properties of Hydroides elegans: Insights from a Multiple Stressor Experiment

PubMed Central

Chan, Vera B. S.; Thiyagarajan, Vengatesen; Lu, Xing Wen; Zhang, Tong; Shih, Kaimin

2013-01-01

The majority of marine benthic invertebrates protect themselves from predators by producing calcareous tubes or shells that have remarkable mechanical strength. An elevation of CO2 or a decrease in pH in the environment can reduce intracellular pH at the site of calcification and thus interfere with animal’s ability to accrete CaCO3. In nature, decreased pH in combination with stressors associated with climate change may result in the animal producing severely damaged and mechanically weak tubes. This study investigated how the interaction of environmental drivers affects production of calcareous tubes by the serpulid tubeworm, Hydroides elegans. In a factorial manipulative experiment, we analyzed the effects of pH (8.1 and 7.8), salinity (34 and 27‰), and temperature (23°C and 29°C) on the biomineral composition, ultrastructure and mechanical properties of the tubes. At an elevated temperature of 29°C, the tube calcite/aragonite ratio and Mg/Ca ratio were both increased, the Sr/Ca ratio was decreased, and the amorphous CaCO3 content was reduced. Notably, at elevated temperature with decreased pH and reduced salinity, the constructed tubes had a more compact ultrastructure with enhanced hardness and elasticity compared to decreased pH at ambient temperature. Thus, elevated temperature rescued the decreased pH-induced tube impairments. This indicates that tubeworms are likely to thrive in early subtropical summer climate. In the context of climate change, tubeworms could be resilient to the projected near-future decreased pH or salinity as long as surface seawater temperature rise at least by 4°C. PMID:24265732

Combined effects of fermentation temperature and pH on kinetic changes of chemical constituents of durian wine fermented with Saccharomyces cerevisiae.

PubMed

Lu, Yuyun; Voon, Marilyn Kai Wen; Huang, Dejian; Lee, Pin-Rou; Liu, Shao-Quan

2017-04-01

This study investigated the effects of temperature (20 and 30 °C) and pH (pH 3.1, 3.9) on kinetic changes of chemical constituents of the durian wine fermented with Saccharomyces cerevisiae. Temperature significantly affected growth of S. cerevisiae EC-1118 regardless of pH with a higher temperature leading to a faster cell death. The pH had a more significant effect on ethanol production than temperature with higher production at 20 °C (5.95%, v/v) and 30 °C (5.56%, v/v) at pH 3.9, relative to that at pH 3.1 (5.25 and 5.01%, v/v). However, relatively higher levels of isobutyl alcohol and isoamyl alcohol up to 64.52 ± 6.39 and 56.27 ± 3.00 mg/L, respectively, were produced at pH 3.1 than at pH 3.9 regardless of temperature. In contrast, production of esters was more affected by temperature than pH, where levels of ethyl esters (ethyl esters of octanoate, nonanoate, and decanoate) and acetate esters (ethyl acetate and isoamyl acetate) were significantly higher up to 2.13 ± 0.23 and 4.61 ± 0.22 mg/L, respectively, at 20 °C than at 30 °C. On the other hand, higher temperature improved the reduction of volatile sulfur compounds. This study illustrated that temperature control would be a more effective tool than pH in modulating the resulting aroma compound profile of durian wine.

Modeling heat resistance of Bacillus weihenstephanensis and Bacillus licheniformis spores as function of sporulation temperature and pH.

PubMed

Baril, Eugénie; Coroller, Louis; Couvert, Olivier; Leguérinel, Ivan; Postollec, Florence; Boulais, Christophe; Carlin, Frédéric; Mafart, Pierre

2012-05-01

Although sporulation environmental factors are known to impact on Bacillus spore heat resistance, they are not integrated into predictive models used to calculate the efficiency of heating processes. This work reports the influence of temperature and pH encountered during sporulation on heat resistance of Bacillus weihenstephanensis KBAB4 and Bacillus licheniformis AD978 spores. A decrease in heat resistance (δ) was observed for spores produced either at low temperature, at high temperature or at acidic pH. Sporulation temperature and pH maximizing the spore heat resistance were identified. Heat sensitivity (z) was not modified whatever the sporulation environmental factors were. A resistance secondary model inspired by the Rosso model was proposed. Sporulation temperatures and pHs minimizing or maximizing the spore heat resistance (T(min(R)), T(opt(R)), T(max(R)), pH(min(R)) and pH(opt(R))) were estimated. The goodness of the model fit was assessed for both studied strains and literature data. The estimation of the sporulation temperature and pH maximizing the spore heat resistance is of great interest to produce spores assessing the spore inactivation in the heating processes applied by the food industry. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of High Temperature Properties and Microstructural Characterization of Resistance Spot Welded Steel Lap Shear Joints

NASA Astrophysics Data System (ADS)

Gupta, R. K.; Anil Kumar, V.; Panicker, Paul G.

2016-02-01

Joining of thin sheets (0.5 mm) of stainless steel 304 and 17-4PH through resistance spot welding is highly challenging especially when joint is used for high temperature applications. Various combinations of stainless steel sheets of thickness 0.5 mm are spot welded and tested at room temperature as well as at high temperatures (800 K, 1,000 K, 1,200 K). Parent metal as well as spot welded joints are tested and characterized. It is observed that joint strength of 17-4PH steel is highest and then dissimilar steel joint of 17-4PH with SS-304 is moderate and of SS-304 is lowest at all the temperatures. Joint strength of 17-4PH steel is found to be >80% of parent metal properties up to 1,000 K then drastic reduction in strength is noted at 1,200 K. Gradual reduction in strength of SS-304 joint with increase in temperature from 800 to 1,200 K is noted. At 1,200 K, joint strength of all combinations of joints is found to be nearly same. Microstructural evaluation of weld nugget after testing at different temperatures shows presence of tempered martensite in 17-4PH containing welds and homogenized structure in stainless steel 304 weld.

Impacts of Ocean Acidification and Temperature Change on Zooxanthellae Density in Coral Stylophora pistillata

NASA Astrophysics Data System (ADS)

Pantaleo, G. E.; Martínez Fernández, A.; Paytan, A.

2016-12-01

As ocean conditions continue to change, marine ecosystems are significantly impacted. Many calcifying organisms are being affected by the gradual changes in ocean pH and temperature that continue to occur over time. Corals are organisms that engage in a symbiotic relationship with Symbiodinium dinoflagellates (zooxanthellae). Symbiodinium are responsible for photosynthetic activity within oligotrophic waters. Corals depend on high levels of aragonite saturation state of seawater in order to build their skeletal structure. Most corals have a relatively narrow optimal range of temperature and pH in which they thrive. However, it is thought that corals residing in the Gulf of Aqaba (Red Sea) are resilient to the effects of increasing temperature. Stylophora pistillata's response to environmental impacts was tested via a simulation of ocean conditions at a high temperature and high CO2 emission scenario (pH 7.65) and lower CO2 emission scenario (pH 7.85) that are predicted for the end of this century. We present the difference in zooxanthellae density following a short term experiment where corals were placed in seawater tanks at pH 7.65, 7.85 and 8.1 and temperature was increased by 4 degrees C above seawater temperature in order to measure the response of Stylophora pistillata to potential future ocean conditions.

Acclimatization to high-variance habitats does not enhance physiological tolerance of two key Caribbean corals to future temperature and pH.

PubMed

Camp, Emma F; Smith, David J; Evenhuis, Chris; Enochs, Ian; Manzello, Derek; Woodcock, Stephen; Suggett, David J

2016-05-25

Corals are acclimatized to populate dynamic habitats that neighbour coral reefs. Habitats such as seagrass beds exhibit broad diel changes in temperature and pH that routinely expose corals to conditions predicted for reefs over the next 50-100 years. However, whether such acclimatization effectively enhances physiological tolerance to, and hence provides refuge against, future climate scenarios remains unknown. Also, whether corals living in low-variance habitats can tolerate present-day high-variance conditions remains untested. We experimentally examined how pH and temperature predicted for the year 2100 affects the growth and physiology of two dominant Caribbean corals (Acropora palmata and Porites astreoides) native to habitats with intrinsically low (outer-reef terrace, LV) and/or high (neighbouring seagrass, HV) environmental variance. Under present-day temperature and pH, growth and metabolic rates (calcification, respiration and photosynthesis) were unchanged for HV versus LV populations. Superimposing future climate scenarios onto the HV and LV conditions did not result in any enhanced tolerance to colonies native to HV. Calcification rates were always lower for elevated temperature and/or reduced pH. Together, these results suggest that seagrass habitats may not serve as refugia against climate change if the magnitude of future temperature and pH changes is equivalent to neighbouring reef habitats. © 2016 The Author(s).

Acclimatization to high-variance habitats does not enhance physiological tolerance of two key Caribbean corals to future temperature and pH

PubMed Central

Smith, David J.; Evenhuis, Chris; Enochs, Ian; Manzello, Derek; Woodcock, Stephen; Suggett, David J.

2016-01-01

Corals are acclimatized to populate dynamic habitats that neighbour coral reefs. Habitats such as seagrass beds exhibit broad diel changes in temperature and pH that routinely expose corals to conditions predicted for reefs over the next 50–100 years. However, whether such acclimatization effectively enhances physiological tolerance to, and hence provides refuge against, future climate scenarios remains unknown. Also, whether corals living in low-variance habitats can tolerate present-day high-variance conditions remains untested. We experimentally examined how pH and temperature predicted for the year 2100 affects the growth and physiology of two dominant Caribbean corals (Acropora palmata and Porites astreoides) native to habitats with intrinsically low (outer-reef terrace, LV) and/or high (neighbouring seagrass, HV) environmental variance. Under present-day temperature and pH, growth and metabolic rates (calcification, respiration and photosynthesis) were unchanged for HV versus LV populations. Superimposing future climate scenarios onto the HV and LV conditions did not result in any enhanced tolerance to colonies native to HV. Calcification rates were always lower for elevated temperature and/or reduced pH. Together, these results suggest that seagrass habitats may not serve as refugia against climate change if the magnitude of future temperature and pH changes is equivalent to neighbouring reef habitats. PMID:27194698

Optimisation of the reaction conditions for the production of cross-linked starch with high resistant starch content.

PubMed

Kahraman, Kevser; Koksel, Hamit; Ng, Perry K W

2015-05-01

The optimum reaction conditions (temperature and pH) for the preparation of cross-linked (CL) corn and wheat starches with maximum resistant starch (RS) content were investigated by using response surface methodology (RSM). According to the preliminary results, five levels were selected for reaction temperature (38-70 °C) and pH (10-12) in the main study. RS contents of the CL corn and wheat starch samples increased with increasing temperature and pH, and pH had a greater influence on RS content than had temperature. The maximum RS content (with a maximum p value of 0.4%) was obtained in wheat starch cross-linked at 38 °C and pH 12. In the case of CL corn starch, the optimum condition was 70 °C and pH 12. CL corn and wheat starch samples were also produced separately under the optimum conditions and their RS contents were 80.4% and 83.9%, respectively. These results were also in agreement with the values predicted by RSM. Copyright © 2014 Elsevier Ltd. All rights reserved.

Optimization study of ethanolic fermentation from oil palm trunk, rubberwood and mixed hardwood hydrolysates using Saccharomyces cerevisiae.

PubMed

Chin, K L; H'ng, P S; Wong, L J; Tey, B T; Paridah, M T

2010-05-01

Ethanolic fermentation using Saccharomyces cerevisiae was carried out on three types of hydrolysates produced from lignocelulosic biomass which are commonly found in Malaysia such as oil palm trunk, rubberwood and mixed hardwood. The effect of fermentation temperature and pH of hydrolysate was evaluated to optimize the fermentation efficiency which defined as maximum ethanol yield in minimum fermentation time. The fermentation process using different temperature of 25 degrees Celsius, 30 degrees Celsius and 40 degrees Celsius were performed on the prepared fermentation medium adjusted to pH 4, pH 6 and pH 7, respectively. Results showed that the fermentation time was significantly reduced with the increase of temperature but an adverse reduction in ethanol yield was observed using temperature of 40 degrees Celsius. As the pH of hydrolysate became more acidic, the ethanol yield increased. Optimum fermentation efficiency for ethanolic fermentation of lignocellulosic hydrolysates using S. cerevisiae can be obtained using 33.2 degrees Celsius and pH 5.3. Copyright 2009 Elsevier Ltd. All rights reserved.

The dinoflagellate Akashiwo sanguinea will benefit from future climate change: The interactive effects of ocean acidification, warming and high irradiance on photophysiology and hemolytic activity.

PubMed

Ou, Guanyong; Wang, Hong; Si, Ranran; Guan, Wanchun

2017-09-01

Due to global climate change, marine phytoplankton will likely experience low pH (ocean acidification), high temperatures and high irradiance in the future. Here, this work report the results of a batch culture experiment conducted to study the interactive effects of elevated CO 2 , increased temperature and high irradiance on the harmful dinoflagellate Akashiwo sanguinea, isolated at Dongtou Island, Eastern China Sea. The A. sanguinea cells were acclimated in high CO 2 condition for about three months before testing the responses of cells to a full factorial matrix experimentation during a 7-day period. This study measured the variation in physiological parameters and hemolytic activity in 8 treatments, representing full factorial combinations of 2 levels each of exposure to CO 2 (400 and 1000μatm), temperature (20 and 28°C) and irradiance (50 and 200μmol photons m -2 s -1 ). Sustained growth of A. sanguinea occurred in all treatments, but high CO 2 (HC) stimulated faster growth than low CO 2 (LC). The pigments (chlorophyll a and carotenoid) decreased in all HC treatments. The quantum yield (F v /F m ) declined slightly in all high-temperature (HT) treatments. High irradiance (HL) induced the accumulation of ultraviolet-absorbing compounds (UV abc ) irrespective of temperature and CO 2 . The hemolytic activity in the LC treatments, however, declined when exposed to HT and HL, but HC alleviated the adverse effects of HT and HL on hemolytic activity. All HC and HL conditions and the combinations of high temperature*high light (HTHL) and high CO 2 *high temperature*high light (HCHTHL) positively affected the growth in comparison to the low CO 2 *low temperature*low light (LCLTLL) treatment. High temperature (HT), high light (HL) and a combination of HT*HL, however, negatively impacted hemolytic activity. CO 2 was the main factor that affected the growth and hemolytic activity. There were no significant interactive effects of CO 2 *temperature*irradiance on growth, pigment, F v /F m or hemolytic activity, but there were effects on P m , α, and E k . If these results are extrapolated to the natural environment, it can be hypothesized that A. sanguinea cells will benefit from the combination of ocean acidification, warming, and high irradiance that are likely to occur under future climate change. It is assumed that faster growth and higher hemolytic activity and UV abc of this species will occur under future conditions compared with those the current CO 2 (400μatm) and temperature (20°C) conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous removal of NO and SO2 using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS).

PubMed

Liu, Yangxian; Wang, Yan; Wang, Qian; Pan, Jianfeng; Zhang, Jun

2018-01-01

Simultaneous removal process of SO 2 and NO from flue gas using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS) in a VUV spraying reactor was proposed. The key influencing factors, active species, reaction products and mechanism of SO 2 and NO simultaneous removal were investigated. The results show that vacuum ultraviolet light (185 nm) achieves the highest NO removal efficiency and yield of and under the same test conditions. NO removal is enhanced at higher PMS concentration, light intensity and oxygen concentration, and is inhibited at higher NO concentration, SO 2 concentration and solution pH. Solution temperature has a double impact on NO removal. CO 2 concentration has no obvious effect on NO removal. and produced from VUV-activation of PMS play a leading role in NO removal. O 3 and ·O produced from VUV-activation of O 2 also play an important role in NO removal. SO 2 achieves complete removal under all experimental conditions due to its very high solubility in water and good reactivity. The highest simultaneous removal efficiency of SO 2 and NO reaches 100% and 91.3%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Oxidation of ethylenethiourea in water via ozone enhanced by UV-C: identification of transformation products.

PubMed

Bottrel, Sue Ellen C; Pereira, Pedro C; de Oliveira Pereira, Renata; Leão, Mônica M D; Amorim, Camila C

2018-06-25

Ethylenethiourea (ETU) is a toxic degradation product of one class of fungicide which is largely employed in the world, the ethylenebisdithiocarbamates. In this study, ETU was degraded by ozonation enhanced by UV-C light irradiation (O 3 /UV-C) in aqueous medium. Degradation experiments were conducted at natural pH (6.8) and neutral pH (7.0, buffered). ETU was promptly eliminated from the reactive medium during ozonation in the presence and absence of light. Within the first few minutes of reaction conducted in natural pH, the pH decreased quickly from 6.8 to 3.0. Results show that ETU mineralization occurs only in the reaction conducted in neutral pH and that it takes place in a higher rate when enhanced by UV-C irradiation. Main intermediates formed during the O3/UV-C experiments in different conditions tested were also investigated and three different degradation mechanisms were proposed considering the occurrence of direct and indirect ozone reactions. At pH 7, ethylene urea (EU) was quickly generated and degraded. Meanwhile, at natural pH, besides EU, other compounds originated from the electrophilic attack of ozone to the sulfur atom present in the contaminant molecule were also identified during reaction and EU was detected within 60 min of reaction. Results showed that ozonation enhanced by UV-C promotes a faster reaction than the same system in the absence of light, and investigation of the toxicity is recommended.

Ethylene-Regulated Floral Volatile Synthesis in Petunia Corollas1[w

PubMed Central

Underwood, Beverly A.; Tieman, Denise M.; Shibuya, Kenichi; Dexter, Richard J.; Loucas, Holly M.; Simkin, Andrew J.; Sims, Charles A.; Schmelz, Eric A.; Klee, Harry J.; Clark, David G.

2005-01-01

In many flowering plants, such as petunia (Petunia × hybrida), ethylene produced in floral organs after pollination elicits a series of physiological and biochemical events, ultimately leading to senescence of petals and successful fertilization. Here, we demonstrate, using transgenic ethylene insensitive (44568) and Mitchell Diploid petunias, that multiple components of emission of volatile organic compounds (VOCs) are regulated by ethylene. Expression of benzoic acid/salicylic acid carboxyl methyltransferase (PhBSMT1 and 2) mRNA is temporally and spatially down-regulated in floral organs in a manner consistent with current models for postpollination ethylene synthesis in petunia corollas. Emission of methylbenzoate and other VOCs after pollination and exogenous ethylene treatment parallels a reduction in PhBSMT1 and 2 mRNA levels. Under cyclic light conditions (day/night), PhBSMT mRNA levels are rhythmic and precede emission of methylbenzoate by approximately 6 h. When shifted into constant dark or light conditions, PhBSMT mRNA levels and subsequent methylbenzoate emission correspondingly decrease or increase to minimum or maximum levels observed during normal conditions, thus suggesting that light may be a more critical influence on cyclic emission of methylbenzoate than a circadian clock. Transgenic PhBSMT RNAi flowers with reduced PhBSMT mRNA levels show a 75% to 99% decrease in methylbenzoate emission, with minimal changes in other petunia VOCs. These results implicate PhBSMT1 and 2 as genes responsible for synthesis of methylbenzoate in petunia. PMID:15849311

Water/ice phase transition: The role of zirconium acetate, a compound with ice-shaping properties

NASA Astrophysics Data System (ADS)

Marcellini, Moreno; Fernandes, Francisco M.; Dedovets, Dmytro; Deville, Sylvain

2017-04-01

Few compounds feature ice-shaping properties. Zirconium acetate is one of the very few inorganic compounds reported so far to have ice-shaping properties similar to that of ice-shaping proteins, encountered in many organisms living at low temperature. When a zirconium acetate solution is frozen, oriented and perfectly hexagonal ice crystals can be formed and their growth follows the temperature gradient. To shed light on the water/ice phase transition while freezing zirconium acetate solution, we carried out differential scanning calorimetry measurements. From our results, we estimate how many water molecules do not freeze because of their interaction with Zr cations. We estimate the colligative properties of the Zr acetate on the apparent critical temperature. We further show that the phase transition is unaffected by the nature of the base which is used to adjust the pH. Our results provide thus new hints on the ice-shaping mechanism of zirconium acetate.

Water/ice phase transition: The role of zirconium acetate, a compound with ice-shaping properties.

PubMed

Marcellini, Moreno; Fernandes, Francisco M; Dedovets, Dmytro; Deville, Sylvain

2017-04-14

Few compounds feature ice-shaping properties. Zirconium acetate is one of the very few inorganic compounds reported so far to have ice-shaping properties similar to that of ice-shaping proteins, encountered in many organisms living at low temperature. When a zirconium acetate solution is frozen, oriented and perfectly hexagonal ice crystals can be formed and their growth follows the temperature gradient. To shed light on the water/ice phase transition while freezing zirconium acetate solution, we carried out differential scanning calorimetry measurements. From our results, we estimate how many water molecules do not freeze because of their interaction with Zr cations. We estimate the colligative properties of the Zr acetate on the apparent critical temperature. We further show that the phase transition is unaffected by the nature of the base which is used to adjust the pH. Our results provide thus new hints on the ice-shaping mechanism of zirconium acetate.

Characterization of Spirulina biomass for CELSS diet potential

NASA Technical Reports Server (NTRS)

Tadros, Mahasin G.

1988-01-01

Spirulina sp. as a bioregenerative photosynthetic and an edible alga for space craft crew in a CELSS, was characterized for growth rate and biomass yield in batch cultures, under various environmental conditions. The cell characteristics were identified for two strains of Spirulina: S. maxima and S. plantensis. Fast growth rate and high yield of both strains were obtained under the following conditions: temperature (30 to 35 C), light irradiance (60 to 100 uE/m/s), nitrate (30 mM), phosphate (2 mM), aeration (300 ml/min), and ph (9 to 10). The partitioning of the assimalatory products (proteins, carbohydrates, lipids) were manipulated by varying the environmental growth conditions. The experiments with Spirulina demonstrated that under stress conditions (high light 120 uE/m/s, temperature 38 C, nitrogen or phosphate limitation; 0.1 M sodium chloride) carbohydrate increased at the expense of protein. In other experiments, where the growth media were sufficient in nutrients and incubated under optimum growth conditions, the total proteins were increased up to almost 70 percent of the organic weight. Conclusion: The nutritional quality of the alga could be manipulated by growth conditions, and therefore usful as a subsystem in CELSS.

Differential-Mode Biosensor Using Dual Extended-Gate Metal-Oxide-Semiconductor Field-Effect Transistors

NASA Astrophysics Data System (ADS)

Choi, Jinhyeon; Lee, Hee Ho; Ahn, Jungil; Seo, Sang-Ho; Shin, Jang-Kyoo

2012-06-01

In this paper, we present a differential-mode biosensor using dual extended-gate metal-oxide-semiconductor field-effect transistors (MOSFETs), which possesses the advantages of both the extended-gate structure and the differential-mode operation. The extended-gate MOSFET was fabricated using a 0.6 µm standard complementary metal oxide semiconductor (CMOS) process. The Au extended gate is the sensing gate on which biomolecules are immobilized, while the Pt extended gate is the dummy gate for use in the differential-mode detection circuit. The differential-mode operation offers many advantages such as insensitivity to the variation of temperature and light, as well as low noise. The outputs were measured using a semiconductor parameter analyzer in a phosphate buffered saline (PBS; pH 7.4) solution. A standard Ag/AgCl reference electrode was used to apply the gate bias. We measured the variation of output voltage with time, temperature, and light intensity. The bindings of self-assembled monolayer (SAM), streptavidin, and biotin caused a variation in the output voltage of the differential-mode detection circuit and this was confirmed by surface plasmon resonance (SPR) experiment. Biotin molecules could be detected up to a concentration of as low as 0.001 µg/ml.

pH-sensitive fluorescent sensors based on europium(III) complexes.

PubMed

Zhang, Xiaolin; Jiao, Yang; Jing, Xu; Wu, Hongmei; He, Guangjie; Duan, Chunying

2011-03-21

New europium(III) complexes Eu(TTA)(2)-DSQ and Eu(TTA)(3)-DR1 were designed and synthesized as new fluorescent pH probes (where HDSQ = 5-(dimethylamino)-N-(4-(2-((8-hydroxyquinolin-2-yl)methylene)hydrazinecarbonyl)phenyl)naphthalene-1-sulfonamide, DR1 = N(1)-(4-(dimethylamino)benzylidene)-N(2)-(rhodamine-6G) lactamethylene-diamine and TTA = thiophentrifluoroacetone). Eu(TTA)(2)-DSQ exhibited high sensitivity in monitoring pH changes in neutral aqueous solution with negligible background fluorescence. Eu(TTA)(3)-DR1 comprised a green light emitting Rhodamine 6G fluorophore and a Eu(III) moiety as the origin of red light. These pH-sensitive emitter components have pK(a) values of 5.0 and 7.2 respectively, and exhibit isolated protonated steps within one molecule. Luminescence titrations demonstrate that Eu(TTA)(3)-DR1 was able to detect pH values at both near neutral pH and acidic pH ranges, and was also able to detect pH in both cultured cells and in vivo.

Possible Association of Ferrous Phosphates and Ferric Sulfates in S-rich Soil on Mars

NASA Astrophysics Data System (ADS)

Mao, J.; Schroeder, C.; Haderlein, S.

2012-12-01

NASA Mars Exploration Rover (MER) Spirit explored Gusev Crater to look for signs of ancient aqueous activity, assess past environmental conditions and suitability for life. Spirit excavated light-toned, S-rich soils at several locations. These are likely of hydrothermal, possibly fumarolic origin. At a location dubbed Paso Robles the light-toned soil was also rich in P - a signature from surrounding rock. While S is mainly bound in ferric hydrated sulfates [1], the mineralogy of P is ill-constrained [2]. P is a key element for life and its mineralogy constrains its availability. Ferrous phases observed in Paso Robles Mössbauer spectra may represent olivine and pyroxene from surrounding basaltic soil [1] or ferrous phosphate minerals [3]. Phosphate is well-known to complex and stabilize Fe 2+ against oxidation to Fe 3+ . Schröder et al. [3] proposed a formation pathway of ferrous phosphate/ferric sulfate associations: sulfuric acid reacts with basalt containing apatite, forming CaSO4 and phosphoric acid. The phosphoric and/or excess sulfuric acid reacts with olivine, forming Fe2+-phosphate and sulfate. The phosphate is less soluble and precipitates. Ferrous sulfate remains in solution and is oxidized as pH increases. To verify this pathway, we dissolved Fe2+-chloride and Na-phosphate salts in sulfuric acid inside an anoxic glovebox. The solution was titrated to pH 6 by adding NaOH when a first precipitate formed, which was ferrous phosphate according to Mössbauer spectroscopy (MB). At that point the solution was removed from the glovebox and allowed to evaporate in the presence of atmospheric oxygen, leading to the oxidation of Fe2+. The evaporation rate was controlled by keeping the suspensions at different temperatures; pH was monitored during the evaporation process. The final precipitates were analyzed by MB and X-Ray Fluorescence (XRF), comparable to MER MB and Alpha Particle X-ray Spectrometer instrument datasets, and complementary techniques such as X-ray diffraction. Fourier Transform Infrared spectroscopy measurements to compare to MER miniature thermal emission spectrometer data are planned. We observed differences depending on the heat source during evaporation. The closest match to Martian data on the basis of Mössbauer spectra was achieved with a suspension evaporated at 80°C on a hot plate, i.e. heated from below with a temperature gradient in the bottle. The Fe2+/FeT ratio matched, and ferrous phases were all phosphate. When heated in a water bath, i.e. without a temperature gradient in the bottle, Fe2+/FeT ratios increased and ferrous sulfates precipitated also. These results indicate that the Martian light-toned S-rich deposits formed by evaporation on the surface where temperature gradients would be expected rather than underground. They confirm that ferrous phosphate/ferric sulfate associations are possible on Mars and could be preserved in the oxygen-free Martian atmosphere. References: [1] Morris et al., J.Geophys. Res. 111 (2006) E02S13; [2] Ming et al., J. Geophys. Res. 111 (2006) E02S12; [3] Schröder et al., GSA Annual Meeting 2008, Paper No. 171-3.

Absorption and fluorescence spectroscopic characterisation of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry)

NASA Astrophysics Data System (ADS)

Shirdel, J.; Zirak, P.; Penzkofer, A.; Breitkreuz, H.; Wolf, E.

2008-09-01

The absorption and fluorescence behaviour of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry) in a pH 8 aqueous buffer solution is studied. The flavin adenine dinucleotide (FAD) cofactor of dCry is identified to be present in its oxidized form (FAD ox), and the 5,10-methenyltetrahydrofolate (MTHF) cofactor is found to be hydrolyzed and oxidized to 10-formyldihydrofolate (10-FDHF). The absorption and the fluorescence behaviour of dCry is investigated in the dark-adapted (receptor) state, the light-adapted (signalling) state, and under long-time violet light exposure. Photo-excitation of FAD ox in dCry causes a reductive electron transfer to the formation of anionic FAD semiquinone (FAD rad - ), and photo-excitation of the generated FAD rad - causes an oxidative electron transfer to the back formation of FAD ox. In light adapted dCry a photo-induced equilibrium between FAD ox and FAD rad - exists. The photo-cycle dynamics of signalling state formation and recovery is discussed. Quantum yields of photo-induced signalling state formation of about 0.2 and of photo-induced back-conversion of about 0.2 are determined. A recovery of FAD rad - to FAD ox in the dark with a time constant of 1.6 min at room temperature is found.

Solid State pH Sensor Based on Light Emitting Diodes (LED) As Detector Platform

PubMed Central

Lau, King Tong; Shepherd, R.; Diamond, Danny; Diamond, Dermot

2006-01-01

A low-power, high sensitivity, very low-cost light emitting diode (LED)-based device developed for low-cost sensor networks was modified with bromocresol green membrane to work as a solid-state pH sensor. In this approach, a reverse-biased LED functioning as a photodiode is coupled with a second LED configured in conventional emission mode. A simple timer circuit measures how long (in microsecond) it takes for the photocurrent generated on the detector LED to discharge its capacitance from logic 1 (+5 V) to logic 0 (+1.7 V). The entire instrument provides an inherently digital output of light intensity measurements for a few cents. A light dependent resistor (LDR) modified with similar sensor membrane was also used as a comparison method. Both the LED sensor and the LDR sensor responded to various pH buffer solutions in a similar way to obtain sigmoidal curves expected of the dye. The pKa value obtained for the sensors was found to agree with the literature value.

Hyperthermophilic archaeal prefoldin shows refolding activity at low temperature.

PubMed

Zako, Tamotsu; Banba, Shinya; Sahlan, Muhamad; Sakono, Masafumi; Terada, Naofumi; Yohda, Masafumi; Maeda, Mizuo

2010-01-01

Prefoldin is a molecular chaperone that captures a protein-folding intermediate and transfers it to a group II chaperonin for correct folding. Previous studies of archaeal prefoldins have shown that prefoldin only possesses holdase activity and is unable to fold unfolded proteins by itself. In this study, we have demonstrated for the first time that a prefoldin from hyperthermophilic archaeon, Pyrococcus horikoshii OT3 (PhPFD), exhibits refolding activity for denatured lysozyme at temperatures relatively lower than physiologically active temperatures. The interaction between PhPFD and denatured lysozyme was investigated by use of a surface plasmon resonance sensor at various temperatures. Although PhPFD showed strong affinity for denatured lysozyme at high temperature, it exhibited relatively weak interactions at lower temperature. The protein-folding seems to occur through binding and release from PhPFD by virtue of the weak affinity. Our results also imply that prefoldin might be able to contribute to the folding of some cellular proteins whose affinity with prefoldin is weak. Copyright 2009 Elsevier Inc. All rights reserved.

Thermal- and pH-Dependent Size Variable Radical Nanoparticles and Its Water Proton Relaxivity for Metal-Free MRI Functional Contrast Agents.

PubMed

Morishita, Kosuke; Murayama, Shuhei; Araki, Takeru; Aoki, Ichio; Karasawa, Satoru

2016-09-16

For development of the metal-free MRI contrast agents, we prepared the supra-molecular organic radical, TEMPO-UBD, carrying TEMPO radical, as well as the urea, alkyl group, and phenyl ring, which demonstrate self-assembly behaviors using noncovalent bonds in an aqueous solution. In addition, TEMPO-UBD has the tertiary amine and the oligoethylene glycol chains (OEGs) for the function of pH and thermal responsiveness. By dynamic light scattering and transmission electron microscopy imaging, the resulting self-assembly was seen to form the spherical nanoparticles 10-150 nm in size. On heating, interestingly, the nanoparticles showed a lower critical solution temperature (LCST) behavior having two-step variation. This double-LCST behavior is the first such example among the supra-molecules. To evaluate of the ability as MRI contrast agents, the values of proton ((1)H) longitudinal relaxivity (r1) were determined using MRI apparatus. In conditions below and above CAC at pH 7.0, the distinguishable r1 values were estimated to be 0.17 and 0.21 mM(-1) s(1), indicating the suppression of fast tumbling motion of TEMPO moiety in a nanoparticle. Furthermore, r1 values became larger in the order of pH 7.0 > 9.0 > 5.0. Those thermal and pH dependencies indicated the possibility of metal-fee MRI functional contrast agents in the future.

Humboldt's spa: microbial diversity is controlled by temperature in geothermal environments

PubMed Central

Sharp, Christine E; Brady, Allyson L; Sharp, Glen H; Grasby, Stephen E; Stott, Matthew B; Dunfield, Peter F

2014-01-01

Over 200 years ago Alexander von Humboldt (1808) observed that plant and animal diversity peaks at tropical latitudes and decreases toward the poles, a trend he attributed to more favorable temperatures in the tropics. Studies to date suggest that this temperature–diversity gradient is weak or nonexistent for Bacteria and Archaea. To test the impacts of temperature as well as pH on bacterial and archaeal diversity, we performed pyrotag sequencing of 16S rRNA genes retrieved from 165 soil, sediment and biomat samples of 36 geothermal areas in Canada and New Zealand, covering a temperature range of 7.5–99 °C and a pH range of 1.8–9.0. This represents the widest ranges of temperature and pH yet examined in a single microbial diversity study. Species richness and diversity indices were strongly correlated to temperature, with R2 values up to 0.62 for neutral–alkaline springs. The distributions were unimodal, with peak diversity at 24 °C and decreasing diversity at higher and lower temperature extremes. There was also a significant pH effect on diversity; however, in contrast to previous studies of soil microbial diversity, pH explained less of the variability (13–20%) than temperature in the geothermal samples. No correlation was observed between diversity values and latitude from the equator, and we therefore infer a direct temperature effect in our data set. These results demonstrate that temperature exerts a strong control on microbial diversity when considered over most of the temperature range within which life is possible. PMID:24430481

Cultured Human Retinal Pigment Epithelial (hRPE) Sheets: A Search for Suitable Storage Conditions.

PubMed

Khan, Ayyad Z; Utheim, Tor P; Reppe, Sjur; Sandvik, Leiv; Lyberg, Torstein; Roald, Borghild B-H; Ibrahim, Ibrahim B; Eidet, Jon R

2018-04-01

The advancement of human retinal pigment epithelial cell (hRPE) replacement therapy is partly dependent on optimization of cell culture, cell preservation, and storage medium. This study was undertaken to search for a suitable storage temperature and storage medium for hRPE. hRPE monolayer sheets were cultured under standard conditions at 37°C and then randomized for storage at six temperatures (4, 16, 20, 24, 28, and 37°C) for 7 days. After revealing a suitable storage temperature, hRPE sheets were subsequently stored with and without the silk protein sericin added to the storage medium. Live/dead assay, light microscopy, pH, and phenotypic expression of various proteins were used to assess cell cultures stored at different temperatures. After 7 days of storage, hRPE morphology was best preserved at 4°C. Addition of sericin to the storage medium maintained the characteristic morphology of the preserved cells, and improved pigmentation and levels of pigmentation-related proteins in the cultured hRPE sheets following a 7-day storage period at 4°C.

A comparative study of diploid versus triploid Atlantic salmon (Salmo salar L.). The effects of rearing temperatures (5, 10 and 15°C) on raw material characteristics and storage quality.

PubMed

Lerfall, Jørgen; Hasli, Pål Rune; Skare, Even Flønes; Olsen, Rolf Erik; Rotabakk, Bjørn Tore; Roth, Bjørn; Slinde, Erik; Egelandsdal, Bjørg

2017-06-15

Several major market operators argue that the current level of knowledge about quality is too scant to justify a switch to a large-scale production of triploid salmon. The aim of the present study was, therefore, to elucidate how rearing conditions (5, 10 and 15°C) affect the flesh quality of triploid Atlantic salmon (Salmo salar L., 1.6±0.3kg). As a reference, diploid salmon kept under equal conditions and with equal genetics were used. The main design discriminant was the holding temperature; increased temperature gave increased blood lactate, rigor index (I r ), drip loss (DL), content of astaxanthin and intensity of redness, but reduced muscle pH, cathepsin activity and fillet lightness. Salmon kept at 10°C grew the fastest. It is concluded that ploidy gave less variation than temperature. Triploids were characterized by lower blood haematocrit (Hct) and I r , higher DL and collagenase activity, and on average, paler and less yellowish fillets. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of physicochemical parameters on in vitro assembly and disassembly kinetics of recombinant triple-layered rotavirus-like particles.

PubMed

Mellado, Maria Candida M; Mena, Jimmy A; Lopes, António; Ramírez, Octavio T; Carrondo, Manuel J T; Palomares, Laura A; Alves, Paula M

2009-11-01

Virus-like particles constitute potentially relevant vaccine candidates. Nevertheless, their behavior in vitro and assembly process needs to be understood in order to improve their yield and quality. In this study we aimed at addressing these issues and for that purpose triple- and double-layered rotavirus-like particles (TLP 2/6/7 and DLP 2/6, respectively) size and zeta potential were measured using dynamic light scattering at different physicochemical conditions, namely pH, ionic strength, and temperature. Both TLP and DLP were stable within a pH range of 3-7 and at 5-25 degrees C. Aggregation occurred at 35-45 degrees C and their disassembly became evident at 65 degrees C. The isoelectric points of TLP and DLP were 3.0 and 3.8, respectively. In vitro kinetics of TLP disassembly was monitored. Ionic strength, temperature, and the chelating agent employed determined disassembly kinetics. Glycerol (10%) stabilized TLP by preventing its disassembly. Disassembled TLP was able to reassemble by dialysis at high calcium conditions. VP7 monomers were added to DLP in the presence of calcium to follow in vitro TLP assembly kinetics; its assembly rate being mostly affected by pH. Finally, DLP and TLP were found to coexist under certain conditions as determined from all reaction products analyzed by capillary electrophoresis. Overall, these results contribute to the design of new strategies for the improvement of TLP yield and quality by reducing the VP7 detachment from TLP. Copyright 2009 Wiley Periodicals, Inc.

Green chemical synthesis of silver nanomaterials with maltodextrin.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tallant, David Robert; Lu, Ping; Lambert, Timothy N.

2010-11-01

Silver nanomaterials have significant application resulting from their optical properties related to surface enhanced Raman spectroscopy, high electrical conductivity, and anti-microbial impact. A 'green chemistry' synthetic approach for silver nanomaterials minimizes the environmental impact of silver synthesis, as well as lowers the toxicity of the reactive agents. Biopolymers have long been used for stabilization of silver nanomaterials during synthesis, and include gum Arabic, heparin, and common starch. Maltodextrin is a processed derivative of starch with lower molecular weight and an increase in the number of reactive reducing aldehyde groups, and serves as a suitable single reactant for the formation ofmore » metallic silver. Silver nanomaterials can be formed under either a thermal route at neutral pH in water or by reaction at room temperature under more alkaline conditions. Deposited silver materials are formed on substrates from near neutral pH solutions at low temperatures near 50 C. Experimental conditions based on material concentrations, pH and reaction time are investigated for development of deposited films. Deposit morphology and optical properties are characterized using SEM and UV-vis techniques. Silver nanoparticles are generated under alkaline conditions by a dissolution-reduction method from precipitated silver (II) oxide. Synthesis conditions were explored for the rapid development of stable silver nanoparticle dispersions. UV-vis absorption spectra, powder X-ray diffraction (PXRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques were used to characterize the nanoparticle formation kinetics and the influence of reaction conditions. The adsorbed content of the maltodextrin was characterized using thermogravimetric analysis (TGA).« less

An eco-friendly dyeing of woolen yarn by Terminalia chebula extract with evaluations of kinetic and adsorption characteristics.

PubMed

Shabbir, Mohd; Rather, Luqman Jameel; Shahid-Ul-Islam; Bukhari, Mohd Nadeem; Shahid, Mohd; Ali Khan, Mohd; Mohammad, Faqeer

2016-05-01

In the present study Terminalia chebula was used as an eco-friendly natural colorant for sustainable textile coloration of woolen yarn with primary emphasis on thermodynamic and kinetic adsorption aspects of dyeing processes. Polyphenols and ellagitannins are the main coloring components of the dye extract. Assessment of the effect of pH on dye adsorption showed an increase in adsorption capacity with decreasing pH. Effect of temperature on dye adsorption showed 80 °C as optimum temperature for wool dyeing with T. chebula dye extract. Two kinetic equations, namely pseudo first-order and pseudo second-order equations, were employed to investigate the adsorption rates. Pseudo second-order model provided the best fit (R (2) = 0.9908) to the experimental data. The equilibrium adsorption data were fitted by Freundlich and Langmuir isotherm models. The adsorption behavior accorded well (R (2) = 0.9937) with Langmuir isotherm model. Variety of eco-friendly and sustainable shades were developed in combination with small amount of metallic mordants and assessed in terms of colorimetric (CIEL(∗) a (∗) b (∗) and K/S) properties measured using spectrophotometer under D65 illuminant (10° standard observer). The fastness properties of dyed woolen yarn against light, washing, dry and wet rubbing were also evaluated.

An eco-friendly dyeing of woolen yarn by Terminalia chebula extract with evaluations of kinetic and adsorption characteristics

PubMed Central

Shabbir, Mohd; Rather, Luqman Jameel; Shahid-ul-Islam; Bukhari, Mohd Nadeem; Shahid, Mohd; Ali Khan, Mohd; Mohammad, Faqeer

2016-01-01

In the present study Terminalia chebula was used as an eco-friendly natural colorant for sustainable textile coloration of woolen yarn with primary emphasis on thermodynamic and kinetic adsorption aspects of dyeing processes. Polyphenols and ellagitannins are the main coloring components of the dye extract. Assessment of the effect of pH on dye adsorption showed an increase in adsorption capacity with decreasing pH. Effect of temperature on dye adsorption showed 80 °C as optimum temperature for wool dyeing with T. chebula dye extract. Two kinetic equations, namely pseudo first-order and pseudo second-order equations, were employed to investigate the adsorption rates. Pseudo second-order model provided the best fit (R2 = 0.9908) to the experimental data. The equilibrium adsorption data were fitted by Freundlich and Langmuir isotherm models. The adsorption behavior accorded well (R2 = 0.9937) with Langmuir isotherm model. Variety of eco-friendly and sustainable shades were developed in combination with small amount of metallic mordants and assessed in terms of colorimetric (CIEL∗a∗b∗ and K/S) properties measured using spectrophotometer under D65 illuminant (10° standard observer). The fastness properties of dyed woolen yarn against light, washing, dry and wet rubbing were also evaluated. PMID:27222752

High-Throughput Biophysical Analysis and Data Visualization of Conformational Stability of an IgG1 Monoclonal Antibody (mAb) After Deglycosylation

PubMed Central

Alsenaidy, Mohammad A.; Kim, Jae Hyun; Majumdar, Ranajoy; Weis, David D.; Joshi, Sangeeta B.; Tolbert, Thomas J.; Middaugh, C. Russell; Volkin, David B.

2013-01-01

The structural integrity and conformational stability of an IgG1 monoclonal antibody (mAb), after partial and complete enzymatic removal of the N-linked Fc glycan, was compared to the untreated mAb over a wide range of temperature (10° to 90°C) and solution pH (3 to 8) using circular dichroism, fluorescence spectroscopy, and static light scattering combined with data visualization employing empirical phase diagrams (EPDs). Subtle to larger stability differences between the different glycoforms were observed. Improved detection of physical stability differences was then demonstrated over narrower pH range (4.0-6.0) using smaller temperature increments, especially when combined with an alternative data visualization method (radar plots). Differential scanning calorimetry and differential scanning fluorimetry were then utilized and also showed an improved ability to detect differences in mAb glycoform physical stability. Based on these results, a two-step methodology was used in which mAb glycoform conformational stability is first screened with a wide variety of instruments and environmental stresses, followed by a second evaluation with optimally sensitive experimental conditions, analytical techniques and data visualization methods. With this approach, high-throughput biophysical analysis to assess relatively subtle conformational stability differences in protein glycoforms is demonstrated. PMID:24114789

High-frequency ultrasound-responsive block copolymer micelle.

PubMed

Wang, Jie; Pelletier, Maxime; Zhang, Hongji; Xia, Hesheng; Zhao, Yue

2009-11-17

Micelles of a diblock copolymer composed of poly(ethylene oxide) and poly(2-tetrahydropyranyl methacrylate) (PEO-b-PTHPMA) in aqueous solution could be disrupted by high-frequency ultrasound (1.1 MHz). It was found that, upon exposure to a high-intensity focused ultrasound (HIFU) beam at room temperature, the pH value of the micellar solution decreased over irradiation time. The infrared spectroscopic analysis of solid block copolymer samples collected from the ultrasound irradiated micellar solution revealed the formation of carboxylic acid dimers and hydroxyl groups. These characterization results suggest that the high-frequency HIFU beam could induce the hydrolysis reaction of THPMA at room temperature resulting in the cleavage of THP groups. The disruption of PEO-b-PTHPMA micelles by ultrasound was investigated by using dynamic light scattering, atomic force microscopy, and fluorescence spectroscopy. On the basis of the pH change, it was found that the disruption process was determined by a number of factors such as the ultrasound power, the micellar solution volume and the location of the focal spot of the ultrasound beam. This study shows the potential to develop ultrasound-sensitive block copolymer micelles by having labile chemical bonds in the polymer structure, and to use the high-frequency HIFU to trigger a chemical reaction for the disruption of micelles.

Measured solubilities and speciations from oversaturation experiments of neptunium, plutonium, and americium in UE-25p No. 1 well water from the Yucca Mountain region: Milestone report 3329-WBS1.2.3.4.1.3.1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nitsche, H.; Roberts, K.; Prussin, T.

1994-04-01

Solubility and speciation are important in understanding aqueous radionuclide transport through the geosphere. They define the source term for transport retardation processes such as sorption and colloid formation. Solubility and speciation data are useful in verifying the validity of geochemical codes that are a part of predictive transport models. Results are presented from solubility and speciation experiments of {sup 237}NpO{sub 2}{sup +}, {sup 239}Pu{sup 4+}, and {sup 241}Am{sup 3+}/Nd{sup 3+} in a modified UE-25p No. 1 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at two different temperatures (25{degree}more » and 60{degree}C) and three pH values (6.0, 7.0, 8.5). The solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The neptunium solubility decreased with increasing temperature and pH. Plutonium concentrations significantly decreased with increasing temperature at pH 6 and 7. The concentration at pH 8.5 hardly decreased at all with increasing temperature. At both temperatures the concentrations were highest at pH 8.5, lowest at pH 7, and in between at pH 6. For the americium/neodymium solutions, the solubility decreased significantly with increasing temperature and increased somewhat with increasing pH.« less

Photobleaching of chromophoric dissolved organic matter (CDOM) in the Yangtze River estuary: kinetics and effects of temperature, pH, and salinity.

PubMed

Song, Guisheng; Li, Yijie; Hu, Suzheng; Li, Guiju; Zhao, Ruihua; Sun, Xin; Xie, Huixiang

2017-06-21

The kinetics and temperature-, pH- and salinity-dependences of photobleaching of chromophoric dissolved organic matter (CDOM) in the Yangtze River estuary (YRE) were evaluated using laboratory solar-simulated irradiation and compared to those of Suwannee River humic substances (SRHSs). Nearly all CDOM in water at the head of the estuary (headwater herein) was photobleachable in both summer and winter, while significant fractions of CDOM (13-29%) were resistant to photobleaching in saltier waters. The photobleaching rate constant in the headwater was 25% higher in summer than that in winter. The absorbed photon-based photobleaching efficiency (PE) increased with temperature following the linear Arrhenius equation. For a 20 °C increase in temperature, PE increased by ∼45% in the headwater and by 70-81% in the saltier waters. PE for YRE samples exhibited minima at pH from 6 to 7 and increased with both lower and higher pH values, contrasting the consistent increase in PE with pH shown by SRHSs. No consistent effect of salinity on PE was observed for both SRHSs and YRE samples. Photobleaching increased the spectral slope coefficient between 275 nm and 295 nm in summer, consistent with the behavior of SRHSs, but decreased it in winter, implying a difference in the molecular composition of chromophores between the two seasons. Temperature, salinity, and pH modified the photoalteration of the spectral shape but their effects varied spatially and seasonally. This study demonstrates that CDOM quality, temperature, and pH should be incorporated into models involving quantification of photobleaching.

Uniformity of environmental conditions and plant growth in a hydroponic culture system for use in a growth room with aerial CO2 control

NASA Technical Reports Server (NTRS)

Vessey, J. K.; York, E. K.; Henry, L. T.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1988-01-01

A portable system of hydroponic culture was developed that maintained temperature, pH, and nutrient concentrations of circulating nutrient solutions. The hydroponic system is used within a controlled-environment room (CER) for control of aerial environment. The CER was equipped with an auto-calibrating system for atmospheric CO2 control. The control systems for the hydroponic chambers were able to maintain acidity within +/- 0.2 pH units and the temperature with +/- 0.5 degree C. Mixing time for the 200-liter volume of solution within a hydroponic chamber was less than 12 min. The CO2 control system was able to maintain aerial concentrations within +/- 10 ppm CO2 during the light period. The only gradient found to occur within the hydroponic chambers or CER was a slight gradient in aerial temperature along the length of hydroponic chambers. Growth of soybeans [Glycine max (L.) Merr.] was characterized during a 3-week period of vegetative development by leaf number and area, plant dry weight, total N content of plants, and N depletion from the nutrient solution. The growth characteristics among populations for three hydroponic chambers within the CER were not significantly different, and the percent standard errors of means of the measurements within populations from each chamber were nearly all less than 10%. Thus, the uniformity of plant growth reflected the uniformity of environmental conditions.

Evaluation of the enzymatic activity and stability of commercial bromelain incorporated in topical formulations.

PubMed

Lourenço, C B; Ataide, J A; Cefali, L C; Novaes, L C D L; Moriel, P; Silveira, E; Tambourgi, E B; Mazzola, P G

2016-10-01

Bromelain is a mixture of proteolytic enzymes found in various tissues of the pineapple plant (Ananas comosus) and other species of Bromeliaceae. Owing to its proteolytic activity, bromelain has been used in the food, medical, pharmaceutical and cosmetic industries, for its cell renewal, anti-ageing, whitening and anti-cellulite properties. This study evaluated the stability of bromelain (commercial powder) incorporated in topical formulations. Bromelain was incorporated at three concentrations, 0.5%, 1.0% and 2.0%, in oil-in-water emulsion and gel, and stored for six months at varying stress conditions. Stability was accessed by measuring the changes in the protein content, enzymatic activity, viscosity, rheology, pH and colour of the selected formulations. The colour of all the samples changed after 180 days of incubation, indicating the concentration-dependence and temperature-sensitive nature of these formulations. No relationship was observed between the changes in the pH, temperature and luminosity exposure in all the samples. Gels proved to be the least preferred base for incorporation of bromelain for use as a topical formulation, owing to its inability to maintain the integrity of bromelain, thereby affecting the formulation characteristics. The emulsion-based formulations at all the concentrations of bromelain were more stable than the gel-based formulation over 180 days of evaluation, at a temperature of 5°C, protected from light. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Survivability and growth kinetics of methanogenic archaea at various pHs and pressures: Implications for deep subsurface life on Mars

NASA Astrophysics Data System (ADS)

Sinha, Navita; Nepal, Sudip; Kral, Timothy; Kumar, Pradeep

2017-02-01

Life as we know it requires liquid water and sufficient liquid water is highly unlikely on the surface of present-day Mars. However, according to thermal models there is a possibility of liquid water in the deep subsurface of Mars. Thus, the martian subsurface, where the pressure and temperature is higher, could potentially provide a hospitable environment for a biosphere. Also, methane has been detected in the Mars' atmosphere. Analogous to Earth's atmospheric methane, martian methane could also be biological in origin. The carbon and energy sources for methanogenesis in the subsurface of Mars could be available by downwelling of atmospheric CO2 into the regolith and water-rock reactions such as serpentinization, respectively. Corresponding analogs of the martian subsurface on Earth might be the active sites of serpentinization at depths where methanogenic thermophilic archaea are the dominant species. Methanogens residing in Earth's hydrothermal environments are usually exposed to a variety of physiological stresses including a wide range of pressures, temperatures, and pHs. Martian geochemical models imply that the pH of probable groundwater varies from 4.96 to 9.13. In this work, we used the thermophilic methanogen, Methanothermobacter wolfeii, which grows optimally at 55oC. Therefore, a temperature of 55oC was chosen for these experiments, possibly simulating Mars' subsurface temperature. A martian geophysical model suggests depth and pressure corresponding to a temperature of 55 °C would be between 1-30 km and 100-3,000 atm respectively. Here, we have simulated Mars deep subsurface pH, pressure, and temperature conditions and have investigated the survivability, growth rate, and morphology of M. wolfeii after exposure to a wide range of pH 5-9) and pressure (1-1200 atm) at a temperature of 55 °C. Interestingly, in this study we have found that M. wolfeii was able to survive at all the pressures and pHs tested at 55 °C. In order to understand the effect of different pHs and pressures on the metabolic activities of M. wolfeii, we also calculated their growth rate by measuring methane concentration in the headspace gas samples at regular intervals. In acidic conditions, the growth rate (γ) of M. wolfeii increased with the increase in pressure. In neutral and alkaline conditions, the growth rate (γ) of M. wolfeii initially increased with pressure, but decreased upon further increase of pressure. To investigate the effect of combined pH, pressure, and temperature on the morphology of M. wolfeii, we took phase contrast images of the cells. We did not find any obvious significant alteration in the morphology of M. wolfeii cells. Methanogens, chemolithoautotrophic anaerobic microorganisms, are considered as ideal model microorganisms for Mars. In light of research presented here, we suggest that at least one methanogen, M. wolfeii, could survive in the deep subsurface environment of Mars.

Quinonoid metal complexes: toward molecular switches.

PubMed

Dei, Andrea; Gatteschi, Dante; Sangregorio, Claudio; Sorace, Lorenzo

2004-11-01

The peculiar redox-active character of quinonoid metal complexes makes them extremely appealing to design materials of potential technological interest. We show here how the tuning of the properties of these systems can be pursued by using appropriate molecular synthetic techniques. In particular, we focus our attention on metal polyoxolene complexes exhibiting intramolecular electron transfer processes involving either the ligand and the metal ion or the two dioxolene moieties of a properly designed ligand thus inducing electronic bistability. The transition between the two metastable electronic states can be induced by different external stimuli such as temperature, pressure, light, or pH suggesting the use of these systems for molecular switches.

Application of selected methods of remote sensing for detecting carbonaceous water pollution

NASA Technical Reports Server (NTRS)

Davis, E. M.; Fosbury, W. J.

1972-01-01

The use of aerial photography to determine the nature and extent of water pollution from carbonaceous materials is discussed. Flights were conducted over the Galveston Bay estuarine complex. Ground truth data were developed from field sampling of the waters in a region near the Houston Ship Channel. Tests conducted in the field were those for the following physical and chemical factors: (1) ph, (2) dissolved oxygen, (3) temperature, and (4) light penetration. Laboratory analyses to determine various properties of the water are described and the types of instruments used are identified. Results of the analyses are presented as charts and graphs.

Validation of a portable, waterproof blood pH analyser for elasmobranchs.

PubMed

Talwar, Brendan; Bouyoucos, Ian A; Shipley, Oliver; Rummer, Jodie L; Mandelman, John W; Brooks, Edward J; Grubbs, R Dean

2017-01-01

Quantifying changes in blood chemistry in elasmobranchs can provide insights into the physiological insults caused by anthropogenic stress, and can ultimately inform conservation and management strategies. Current methods for analysing elasmobranch blood chemistry in the field are often costly and logistically challenging. We compared blood pH values measured using a portable, waterproof pH meter (Hanna Instruments HI 99161) with blood pH values measured by an i-STAT system (CG4+ cartridges), which was previously validated for teleost and elasmobranch fishes, to gauge the accuracy of the pH meter in determining whole blood pH for the Cuban dogfish ( Squalus cubensis ) and lemon shark ( Negaprion brevirostris ). There was a significant linear relationship between values derived via the pH meter and the i-STAT for both species across a wide range of pH values and temperatures (Cuban dogfish: 6.8-7.1 pH 24-30°C; lemon sharks: 7.0-7.45 pH 25-31°C). The relative error in the pH meter's measurements was ~±2.7%. Using this device with appropriate correction factors and consideration of calibration temperatures can result in both a rapid and accurate assessment of whole blood pH, at least for the two elasmobranch species examined here. Additional species should be examined in the future across a wide range of temperatures to determine whether correction factors are universal.

Spectrophotometric analysis of flavonoid-DNA binding interactions at physiological conditions

NASA Astrophysics Data System (ADS)

Janjua, Naveed Kausar; Siddiqa, Asima; Yaqub, Azra; Sabahat, Sana; Qureshi, Rumana; Haque, Sayed ul

2009-12-01

Mode of interactions of three flavonoids [morin (M), quercetin (Q), and rutin (R)] with chicken blood ds.DNA (ck.DNA) has been investigated spectrophotometrically at different temperatures including body temperature (310 K) and at two physiological pH values, i.e. 7.4 (human blood pH) and 4.7 (stomach pH). The binding constants, Kf, evaluated using Benesi-Hildebrand equation showed that the flavonoids bind effectively through intercalation at both pH values and body temperature. Quercetin, somehow, showed greater binding capabilities with DNA. The free energies of flavonoid-DNA complexes indicated the spontaneity of their binding. The order of binding constants of three flavonoids at both pH values were found to be Kf(Q) > Kf(R) > Kf(M) and at 310 K.

Light-enabled reversible self-assembly and tunable optical properties of stable hairy nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Yihuang; Wang, Zewei; He, Yanjie; Yoon, Young Jun; Jung, Jaehan; Zhang, Guangzhao; Lin, Zhiqun

2018-02-01

The ability to dynamically organize functional nanoparticles (NPs) via the use of environmental triggers (temperature, pH, light, or solvent polarity) opens up important perspectives for rapid and convenient construction of a rich variety of complex assemblies and materials with new structures and functionalities. Here, we report an unconventional strategy for crafting stable hairy NPs with light-enabled reversible and reliable self-assembly and tunable optical properties. Central to our strategy is to judiciously design amphiphilic star-like diblock copolymers comprising inner hydrophilic blocks and outer hydrophobic photoresponsive blocks as nanoreactors to direct the synthesis of monodisperse plasmonic NPs intimately and permanently capped with photoresponsive polymers. The size and shape of hairy NPs can be precisely tailored by modulating the length of inner hydrophilic block of star-like diblock copolymers. The perpetual anchoring of photoresponsive polymers on the NP surface renders the attractive feature of self-assembly and disassembly of NPs on demand using light of different wavelengths, as revealed by tunable surface plasmon resonance absorption of NPs and the reversible transformation of NPs between their dispersed and aggregated states. The dye encapsulation/release studies manifested that such photoresponsive NPs may be exploited as smart guest molecule nanocarriers. By extension, the star-like block copolymer strategy enables the crafting of a family of stable stimuli-responsive NPs (e.g., temperature- or pH-sensitive polymer-capped magnetic, ferroelectric, upconversion, or semiconducting NPs) and their assemblies for fundamental research in self-assembly and crystallization kinetics of NPs as well as potential applications in optics, optoelectronics, magnetic technologies, sensory materials and devices, catalysis, nanotechnology, and biotechnology.

Temperature and pH sensors based on graphenic materials.

PubMed

Salvo, P; Calisi, N; Melai, B; Cortigiani, B; Mannini, M; Caneschi, A; Lorenzetti, G; Paoletti, C; Lomonaco, T; Paolicchi, A; Scataglini, I; Dini, V; Romanelli, M; Fuoco, R; Di Francesco, F

2017-05-15

Point-of-care applications and patients' real-time monitoring outside a clinical setting would require disposable and durable sensors to provide better therapies and quality of life for patients. This paper describes the fabrication and performances of a temperature and a pH sensor on a biocompatible and wearable board for healthcare applications. The temperature sensor was based on a reduced graphene oxide (rGO) layer that changed its electrical resistivity with the temperature. When tested in a human serum sample between 25 and 43°C, the sensor had a sensitivity of 110±10Ω/°C and an error of 0.4±0.1°C compared with the reference value set in a thermostatic bath. The pH sensor, based on a graphene oxide (GO) sensitive layer, had a sensitivity of 40±4mV/pH in the pH range between 4 and 10. Five sensor prototypes were tested in a human serum sample over one week and the maximum deviation of the average response from reference values obtained by a glass electrode was 0.2pH units. For biological applications, the temperature and pH sensors were successfully tested for in vitro cytotoxicity with human fibroblast cells (MRC-5) over 24h. Copyright © 2017 Elsevier B.V. All rights reserved.

The structure and stability of aqueous rare-earth elements in hydrothermal fluids: New results on neodymium(III) aqua and chloroaqua complexes in aqueous solutions to 500 °C and 520 MPa

USGS Publications Warehouse

Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2009-01-01

X-ray absorption spectroscopy (XAS) measurements were made at the Nd L3-edge on neodymium(III) aqua and chloroaqua complexes in low pH aqueous solutions from 25 to 500????C and up to 520??MPa. Analysis of the extended X-ray absorption fine structure of the XAS spectra measured from a 0.07??m Nd/0.16??m HNO3 aqueous solution reveals a contraction of the Nd-O distance of the Nd3+ aqua ion at a uniform rate of ~ 0.013????/100????C and a uniform reduction of the number of coordinated H2O molecules from 10.0 ?? 0.9 to 7.4 ?? 0.9 over the range from 25 to 500????C and up to 370??MPa. The rate of reduction of the first-shell water molecules with temperature for Nd3+ (26%) is intermediate between the rate for the Gd3+ aqua ion (22% from 25 to 500????C) and the rates for the Eu3+ (29% from 25 to 400????C) and the Yb3+ aqua ions (42% from 25 to 500????C) indicating an intermediate stability of the Nd3+ aqua ion consistent with the tetrad effect. Nd L3-edge XAS measurements of 0.05??m NdCl3 aqueous solution at 25 to 500????C and up to 520??MPa show that stepwise inner-sphere complexes most likely of the type Nd(H2O)?? - nCln+3 - n occur in the solution at elevated temperatures, where ?? ??? 9 at 150????C decreasing to ~ 6 at 500????C and the number of chloride ions (n) of the chloroaqua complexes increases uniformly with temperature from 1.2 ?? 0.2 to 2.0 ?? 0.2 in the solution upon increase of temperature from 150 to 500????C. Conversely, the number of H2O ligands of Nd(H2O)?? - nCln+3 - n complexes is uniformly reduced with temperature from 7.5 ?? 0.8 to 3.7 ?? 0.3 in the aqueous solution, in the same temperature range. These data show greater stability of neodymium(III) than gadolinium(III) and ytterbium(III) chloride complexes in low pH aqueous solutions at elevated temperatures. Our data suggest a greater stability of aqueous light REE than that of heavy REE chloride complexes in low pH fluids at elevated temperatures consistent with REE analysis of fluids from deep-sea hydrothermal vents. ?? 2008 Elsevier B.V.

Vulnerability of the calcifying larval stage of the Antarctic sea urchin Sterechinus neumayeri to near-future ocean acidification and warming.

PubMed

Byrne, Maria; Ho, Melanie A; Koleits, Lucas; Price, Casandra; King, Catherine K; Virtue, Patti; Tilbrook, Bronte; Lamare, Miles

2013-07-01

Stenothermal polar benthic marine invertebrates are highly sensitive to environmental perturbations but little is known about potential synergistic effects of concurrent ocean warming and acidification on development of their embryos and larvae. We examined the effects of these stressors on development to the calcifying larval stage in the Antarctic sea urchin Sterechinus neumayeri in embryos reared in present and future (2100+) ocean conditions from fertilization. Embryos were reared in 2 temperature (ambient: -1.0 °C, + 2 °C : 1.0 °C) and 3 pH (ambient: pH 8.0, -0.2-0.4 pH units: 7.8,7.6) levels. Principle coordinates analysis on five larval metrics showed a significant effect of temperature and pH on the pattern of growth. Within each temperature, larvae were separated by pH treatment, a pattern primarily influenced by larval arm and body length. Growth was accelerated by temperature with a 20-28% increase in postoral (PO) length at +2 °C across all pH levels. Growth was strongly depressed by reduced pH with a 8-19% decrease in PO length at pH 7.6-7.8 at both temperatures. The boost in growth caused by warming resulted in larvae that were larger than would be observed if acidification was examined in the absence of warming. However, there was no significant interaction between these stressors. The increase in left-right asymmetry and altered body allometry indicated that decreased pH disrupted developmental patterning and acted as a teratogen (agent causing developmental malformation). Decreased developmental success with just a 2 °C warming indicates that development in S. neumayeri is particularly sensitive to increased temperature. Increased temperature also altered larval allometry. Altered body shape impairs swimming and feeding in echinoplutei. In the absence of adaptation, it appears that the larval phase may be a bottleneck for survivorship of S. neumayeri in a changing ocean in a location where poleward migration to escape inhospitable conditions is not possible. © 2013 Blackwell Publishing Ltd.

40 CFR 411.15 - Standards of performance for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... exceed 3 °C rise above inlet temperature. pH Within the range 6.0 to 9.0. English units (lb/1,000 lb of product) TSS 0.005. Temperature (heat) Not to exceed 3 °C rise above inlet temperature. pH Within the...

40 CFR 411.15 - Standards of performance for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... exceed 3 °C rise above inlet temperature. pH Within the range 6.0 to 9.0. English units (lb/1,000 lb of product) TSS 0.005. Temperature (heat) Not to exceed 3 °C rise above inlet temperature. pH Within the...

``Smart'' Surfaces of Polymer Brushes

NASA Astrophysics Data System (ADS)

Wang, Qiang; Meng, Dong

2009-03-01

``Smart'' surfaces, also known as stimuli-responsive surfaces, can change their properties (e.g., wettability, adhesion, friction, elasticity, and biocompatibility) in response to external stimuli (e.g., temperature, pressure, light, solvent selectivity, ionic strength, type of salt, pH, applied electric field, etc.). In this work, we use numerical self-consistent field calculations to study in detail the structure and stimuli- responses of various polymer brushes, including (1) the thermo- response of PNIPAM brushes in water, (2) solvent-response of uncharged diblock copolymer brushes, and (3) the stimuli- response of charged two-component polymer brushes (including both the binary A/B brushes and diblock copolymer A-B brushes) to ionic strength, pH, and applied electric field. Among the many design parameters (e.g., chain lengths, grafting densities, A-B incompatibility, degree of ionization of charged polymers, etc.) we identify those that strongly affect the surface switchability. Such knowledge is useful to the experimental design of these smart polymer brushes for their applications.

Thymol nanoencapsulated by sodium caseinate: physical and antilisterial properties.

PubMed

Pan, Kang; Chen, Huaiqiong; Davidson, P Michael; Zhong, Qixin

2014-02-19

In this work, thymol was encapsulated in sodium caseinate using high shear homogenization. The transparent dispersion at neutral pH was stable for 30 days at room temperature as determined by dynamic light scattering and atomic force microscopy, which agreed with high ζ potential of nanoparticles. The slightly decreased particle dimension during storage indicates the absence of Ostwald ripening. When molecular binding was studied by fluorescence spectroscopy, thymol was observed to bind with tyrosine and possibly other amino acid residues away from tryptophan of caseins. At pH 4.6 (isoelectric point of caseins), the stabilization of thymol nanoparticles against aggregation was enabled by soluble soybean polysaccharide, resulting from the combined electrostatic and steric repulsions. The encapsulated thymol showed the significantly improved antilisterial activity in milk with different fat levels when compared to thymol crystals, resulting from the quicker mixing and increased solubility in the milk serum. The transparent thymol nanodispersions have promising applications to improve microbiological safety and quality of foods.

Total internal reflection and dynamic light scattering microscopy of gels

NASA Astrophysics Data System (ADS)

Gregor, Brian F.

Two different techniques which apply optical microscopy in novel ways to the study of biological systems and materials were built and applied to several samples. The first is a system for adapting the well-known technique of dynamic light scattering (DLS) to an optical microscope. This can detect and scatter light from very small volumes, as compared to standard DLS which studies light scattering from volumes 1000x larger. The small scattering volume also allows for the observation of nonergodic dynamics in appropriate samples. Porcine gastric mucin (PGM) forms a gel at low pH which lines the epithelial cell layer and acts as a protective barrier against the acidic stomach environment. The dynamics and microscopic viscosity of PGM at different pH levels is studied using polystyrene microspheres as tracer particles. The microscopic viscosity and microrheological properties of the commercial basement membrane Matrigel are also studied with this instrument. Matrigel is frequently used to culture cells and its properties remain poorly determined. Well-characterized and purely synthetic Matrigel substitutes will need to have the correct rheological and morphological characteristics. The second instrument designed and built is a microscope which uses an interferometry technique to achieve an improvement in resolution 2.5x better in one dimension than the Abbe diffraction limit. The technique is based upon the interference of the evanescent field generated on the surface of a prism by a laser in a total internal reflection geometry. The enhanced resolution is demonstrated with fluorescent samples. Additionally. Raman imaging microscopy is demonstrated using the evanescent field in resonant and non-resonant samples, although attempts at applying the enhanced resolution technique to the Raman images were ultimately unsuccessful. Applications of this instrument include high resolution imaging of cell membranes and macroscopic structures in gels and proteins. Finally, a third section incorporating previous research on simulations of complex fluids is included. Two dimensional simulations of oil, water, and surfactant mixtures were computed with a lattice gas method. The simulated systems were randomly mixed and then the temperature was quenched to a predetermined point. Spontaneous micellization is observed for a narrow range of temperature quenches, and the overall growth rate of macroscopic structure is found to follow a Vogel-Fulcher growth law.

Effects of Mo Content on Microstructure and Mechanical Property of PH13-8Mo Martensitic Precipitation-Hardened Stainless Steel

NASA Astrophysics Data System (ADS)

Yubing, Pei; Tianjian, Wang; Zhenhuan, Gao; Hua, Fan; Gongxian, Yang

This paper introduces the effects of Mo content on microstructure and mechanical property of PH13-8Mo martensitic precipitation-hardened stainless steel which is used for LP last stage blade in steam turbine. Thermodynamic software Thermo-Calc has been used to calculate precipitation temperature and the mass fraction of precipitated phases in PH13-8Mo steel with different Mo content. The result shows that when the mass of Mo is below 0.6wt.%, chi-phase mu-phase and sigma-phase could disappear. The microstructure and mechanical property of high Mo PH13-8Mo (Mo=0.57wt.%) and low Mo PH13-8Mo (Mo=2.15wt.%)have been investigated in different heat treatments. The investigations reveal that austenitizing temperature decrease with the reduce of Mo content, so the optimum solution temperature for low Mo PH13-8Mo is lower than that for high Mo PH13-8Mo.The influence of solution temperature on grain size is weakened with the increase of Mo content, Mo rich carbides could retard coarsening of grain. An enormous amount of nano-size uniformly distributed β-NiAl particles are found in both kinds of steels using transmission electron microscopy, they are the most important strengthening phase in PH13-8Mo.

Impact of alternative antimicrobial commercial egg washes on reducing Salmonella contamination

USDA-ARS?s Scientific Manuscript database

Introduction: Table eggs are washed with an alkaline detergent at approximately pH 11 and at a temperature at least 32°C, followed by a chlorine rinse. Both wash temperature and an antimicrobial rinse are required by regulation, but wash pH is not specified. At this pH, little, if any, free chlorine...

Modeling carbon dioxide effect in a controlled atmosphere and its interactions with temperature and pH on the growth of L. monocytogenes and P. fluorescens.

PubMed

Couvert, Olivier; Guégan, Stéphanie; Hézard, Bernard; Huchet, Véronique; Lintz, Adrienne; Thuault, Dominique; Stahl, Valérie

2017-12-01

The effect of carbon dioxide, temperature, and pH on growth of Listeria monocytogenes and Pseudomonas fluorescens was studied, following a protocol to monitor microbial growth under a constant gas composition. In this way, the CO 2 dissolution didn't modify the partial pressures in the gas phase. Growth curves were acquired at different temperatures (8, 12, 22 and 37 °C), pH (5.5 and 7) and CO 2 concentration in the gas phase (0, 20, 40, 60, 80, 100% of the atmospheric pressure, and over 1 bar). These three factors greatly influenced the growth rate of L. monocytogenes and P. fluorescens, and significant interactions have been observed between the carbon dioxide and the temperature effects. Results showed no significant effect of the CO 2 concentration at 37 °C, which may be attributed to low CO2 solubility at high temperature. An inhibitory effect of CO 2 appeared at lower temperatures (8 and 12 °C). Regardless of the temperature, the gaseous CO 2 is sparingly soluble at acid pH. However, the CO 2 inhibition was not significantly different between pH 5.5 and pH 7. Considering the pKa of the carbonic acid, these results showed the dissolved carbon under HCO 3 - form didn't affect the bacterial inhibition. Finally, a global model was proposed to estimate the growth rate vs. CO 2 concentration in the aqueous phase. This dissolved concentration is calculated according to the physical equations related to the CO 2 equilibriums, involving temperature and pH interactions. This developed model is a new tool available to manage the food safety of MAP. Copyright © 2017 Elsevier Ltd. All rights reserved.

Activation Energy of the Low-pH-Induced Lamellar to Bicontinuous Cubic Phase Transition in Dioleoylphosphatidylserine/Monoolein.

PubMed

Oka, Toshihiko; Saiki, Takahiro; Alam, Jahangir Md; Yamazaki, Masahito

2016-02-09

Electrostatic interaction is an important factor for phase transitions between lamellar liquid-crystalline (Lα) and inverse bicontinuous cubic (QII) phases. We investigated the effect of temperature on the low-pH-induced Lα to double-diamond cubic (QII(D)) phase transition in dioleoylphosphatidylserine (DOPS)/monoolein (MO) using time-resolved small-angle X-ray scattering with a stopped-flow apparatus. Under all conditions of temperature and pH, the Lα phase was directly transformed into an intermediate inverse hexagonal (HII) phase, and subsequently the HII phase slowly converted to the QII(D) phase. We obtained the rate constants of the initial step (i.e., the Lα to HII phase transition) and of the second step (i.e., the HII to QII(D) phase transition) using the non-negative matrix factorization method. The rate constant of the initial step increased with temperature. By analyzing this result, we obtained the values of its apparent activation energy, Ea (Lα → HII), which did not change with temperature but increased with an increase in pH. In contrast, the rate constant of the second step decreased with temperature at pH 2.6, although it increased with temperature at pH 2.7 and 2.8. These results indicate that the value of Ea (HII → QII(D)) at pH 2.6 increased with temperature, but the values of Ea (HII → QII(D)) at pH 2.7 and 2.8 were constant with temperature. The values of Ea (HII → QII(D)) were smaller than those of Ea (Lα → HII) at the same pH. We analyzed these results using a modified quantitative theory on the activation energy of phase transitions of lipid membranes proposed initially by Squires et al. (Squires, A. M.; Conn, C. E.; Seddon, J. M.; Templer, R. H. Soft Matter 2009, 5, 4773). On the basis of these results, we discuss the mechanism of this phase transition.

Effects of pH and Temperature on the Stability of Fumonisins in Maize Products.

PubMed

Bryła, Marcin; Waśkiewicz, Agnieszka; Szymczyk, Krystyna; Jędrzejczak, Renata

2017-03-01

This paper is a study of the stability of fumonisins in dough based on maize flour prepared in a phosphate buffer with a pH of 3.5, 5.5 or 7.5 and baked at a temperature within the range of 100-250 °C. Buffers with various pH values were tested, since it is well-known that pH may significantly influence interactions of fumonisins with other substances. A standard analytical procedure was used to determine the concentration of free fumonisins. Hydrolysis in an alkaline medium was then applied to reveal the hidden forms, while the total fumonisins concentations was determined in another measurement. The total concentration of fumonisins was statistically higher in pH = 3.5 and pH = 5.5 than the concentration of free fumonisins; no similar difference was found at pH = 7.5. The applied phosphate buffer pH 7.5 may enhance solubility of fumonisins, which would increase extraction efficiency of free analytes, thereby decreasing the difference between concentrations of total and free fumonisins. Hydrolysed B₁ fumonisin (HFB₁) and partially hydrolysed B₁ fumonisin (isomers a and b: PHFB 1a and PHFB 1b , respectively) were the main investigated substances. For baking temperatures below 220 °C, fumonisins were slightly more stable for pH = 5.5 than for pH = 3.5 and pH = 7.5. In both of these latter cases, the concentration of partially hydrolysed fumonisins grew initially (up to 200 °C) with an increase in the baking temperature, and then dropped. Similar behaviour was observed for free HFB₁, which may suggest the following fumonisin degradation mechanism: initially, the tricarballylic acid (TCA) groups are removed from the molecules, and next, the HFB₁ molecules disintegrate.

Effects of pH and Temperature on the Stability of Fumonisins in Maize Products

PubMed Central

Bryła, Marcin; Waśkiewicz, Agnieszka; Szymczyk, Krystyna; Jędrzejczak, Renata

2017-01-01

This paper is a study of the stability of fumonisins in dough based on maize flour prepared in a phosphate buffer with a pH of 3.5, 5.5 or 7.5 and baked at a temperature within the range of 100–250 °C. Buffers with various pH values were tested, since it is well-known that pH may significantly influence interactions of fumonisins with other substances. A standard analytical procedure was used to determine the concentration of free fumonisins. Hydrolysis in an alkaline medium was then applied to reveal the hidden forms, while the total fumonisins concentations was determined in another measurement. The total concentration of fumonisins was statistically higher in pH = 3.5 and pH = 5.5 than the concentration of free fumonisins; no similar difference was found at pH = 7.5. The applied phosphate buffer pH 7.5 may enhance solubility of fumonisins, which would increase extraction efficiency of free analytes, thereby decreasing the difference between concentrations of total and free fumonisins. Hydrolysed B1 fumonisin (HFB1) and partially hydrolysed B1 fumonisin (isomers a and b: PHFB1a and PHFB1b, respectively) were the main investigated substances. For baking temperatures below 220 °C, fumonisins were slightly more stable for pH = 5.5 than for pH = 3.5 and pH = 7.5. In both of these latter cases, the concentration of partially hydrolysed fumonisins grew initially (up to 200 °C) with an increase in the baking temperature, and then dropped. Similar behaviour was observed for free HFB1, which may suggest the following fumonisin degradation mechanism: initially, the tricarballylic acid (TCA) groups are removed from the molecules, and next, the HFB1 molecules disintegrate. PMID:28257053

Modulation of the photoluminescence in carbon dots through surface modification: from mechanism to white light-emitting diodes.

PubMed

Zhu, Jinyang; Shao, He; Bai, Xue; Zhai, Yue; Zhu, Yongsheng; Chen, Xu; Pan, Gencai; Dong, Biao; Xu, Lin; Zhang, Hanzhuang; Song, Hongwei

2018-06-15

Carbon dots (CDs) have emerged as a new type of fluorescent material because of their unique optical advantages, such as high photoluminescence quantum yields (QYs), excellent photo-stability, excitation-dependent emissions, and low toxicity. However, the photoluminescence mechanism for CDs remains unclear, which limits their further practical application. Here, CDs were synthesized via a solvothermal route from citric acid and urea. Through the oxidation and reduction treatment of pristine CDs, the origin of the photoluminescence and the involved mechanism were revealed. We found that the blue/green/red emissions originated from three diverse emitting states, i.e. the intrinsic state, and C=O- and C=N-related surface states, respectively. Based on the as-prepared CDs, a pH sensor depending on the radiometric luminescence detection was developed. Furthermore, we constructed CD/PVP (PVP, polyvinylpyrrolidone) composite films, which exhibited white light emission with photoluminescence QYs of 15.3%. The white light emission with different correlated color temperatures (CCTs), from 4807 K to 3319 K, was obtained by simply changing the amount of PVP solution. Benefiting from the white light-emitting solid-state films, single-component white light-emitting diodes were fabricated with an average color rendering index value (Ra) of 80.0, luminous efficiency of 10.2 lm W -1 , and good working stability, thus indicating a promising potential for practical lighting applications.

Modulation of the photoluminescence in carbon dots through surface modification: from mechanism to white light-emitting diodes

NASA Astrophysics Data System (ADS)

Zhu, Jinyang; Shao, He; Bai, Xue; Zhai, Yue; Zhu, Yongsheng; Chen, Xu; Pan, Gencai; Dong, Biao; Xu, Lin; Zhang, Hanzhuang; Song, Hongwei

2018-06-01

Carbon dots (CDs) have emerged as a new type of fluorescent material because of their unique optical advantages, such as high photoluminescence quantum yields (QYs), excellent photo-stability, excitation-dependent emissions, and low toxicity. However, the photoluminescence mechanism for CDs remains unclear, which limits their further practical application. Here, CDs were synthesized via a solvothermal route from citric acid and urea. Through the oxidation and reduction treatment of pristine CDs, the origin of the photoluminescence and the involved mechanism were revealed. We found that the blue/green/red emissions originated from three diverse emitting states, i.e. the intrinsic state, and C=O- and C=N-related surface states, respectively. Based on the as-prepared CDs, a pH sensor depending on the radiometric luminescence detection was developed. Furthermore, we constructed CD/PVP (PVP, polyvinylpyrrolidone) composite films, which exhibited white light emission with photoluminescence QYs of 15.3%. The white light emission with different correlated color temperatures (CCTs), from 4807 K to 3319 K, was obtained by simply changing the amount of PVP solution. Benefiting from the white light-emitting solid-state films, single-component white light-emitting diodes were fabricated with an average color rendering index value (Ra) of 80.0, luminous efficiency of 10.2 lm W‑1, and good working stability, thus indicating a promising potential for practical lighting applications.

Sperm motility in fishes. I. Effects of temperature and pH: a review.

PubMed

Alavi, Sayyed Mohammad Hadi; Cosson, Jacky

2005-02-01

Sperm motility is a key factor in allowing us to determine semen quality and fertilizing capacity. Motility in semen is mainly controlled by K+ in salmonids, and probably also in sturgeons, and by osmotic pressure in other freshwater and seawater fish species, but other factors, such as concentration of surrounding metabolites and ions (Ca2+, Mg2+, etc.), pH and temperature also influence motility characteristics. In the present study, we have mainly reviewed and summarized the effects of temperature and pH on the motility of spermatozoa in three fish species: salmonids, cyprinids and sturgeons. Data in the literature show that motility, fertilizing ability and velocity of spermatozoa, as well as the duration of the motility period, depend on the temperature of the assay medium and also of that of the brood fish holding tank. In contrast, the pH of the swimming medium, and thus the intracellular pH of spermatozoa, has less influence on sperm motility parameters in cyprinids, salmonids and sturgeons.

Photo-Responsive Graphene and Carbon Nanotubes to Control and Tackle Biological Systems.

PubMed

Cardano, Francesca; Frasconi, Marco; Giordani, Silvia

2018-01-01

Photo-responsive multifunctional nanomaterials are receiving considerable attention for biological applications because of their unique properties. The functionalization of the surface of carbon nanotubes (CNTs) and graphene, among other carbon based nanomaterials, with molecular switches that exhibit reversible transformations between two or more isomers in response to different kind of external stimuli, such as electromagnetic radiation, temperature and pH, has allowed the control of the optical and electrical properties of the nanomaterial. Light-controlled molecular switches, such as azobenzene and spiropyran, have attracted a lot of attention for nanomaterial's functionalization because of the remote modulation of their physicochemical properties using light stimulus. The enhanced properties of the hybrid materials obtained from the coupling of carbon based nanomaterials with light-responsive switches has enabled the fabrication of smart devices for various biological applications, including drug delivery, bioimaging and nanobiosensors. In this review, we highlight the properties of photo-responsive carbon nanomaterials obtained by the conjugation of CNTs and graphene with azobenzenes and spiropyrans molecules to investigate biological systems, devising possible future directions in the field.

Smart material platforms for miniaturized devices: implications in disease models and diagnostics.

PubMed

Verma, Ritika; Adhikary, Rishi Rajat; Banerjee, Rinti

2016-05-24

Smart materials are responsive to multiple stimuli like light, temperature, pH and redox reactions with specific changes in state. Various functionalities in miniaturised devices can be achieved through the application of "smart materials" that respond to changes in their surroundings. The change in state of the materials in the presence of a stimulus may be used for on demand alteration of flow patterns in devices, acting as microvalves, as scaffolds for cellular aggregation or as modalities for signal amplification. In this review, we discuss the concepts of smart trigger responsive materials and their applications in miniaturized devices both for organ-on-a-chip disease models and for point-of-care diagnostics. The emphasis is on leveraging the smartness of these materials for example, to allow on demand sample actuation, ion dependent spheroid models for cancer or light dependent contractility of muscle films for organ-on-a-chip applications. The review throws light on the current status, scope for technological enhancements, challenges for translation and future prospects of increased incorporation of smart materials as integral parts of miniaturized devices.

Photo-Responsive Graphene and Carbon Nanotubes to Control and Tackle Biological Systems

PubMed Central

Cardano, Francesca; Frasconi, Marco; Giordani, Silvia

2018-01-01

Photo-responsive multifunctional nanomaterials are receiving considerable attention for biological applications because of their unique properties. The functionalization of the surface of carbon nanotubes (CNTs) and graphene, among other carbon based nanomaterials, with molecular switches that exhibit reversible transformations between two or more isomers in response to different kind of external stimuli, such as electromagnetic radiation, temperature and pH, has allowed the control of the optical and electrical properties of the nanomaterial. Light-controlled molecular switches, such as azobenzene and spiropyran, have attracted a lot of attention for nanomaterial's functionalization because of the remote modulation of their physicochemical properties using light stimulus. The enhanced properties of the hybrid materials obtained from the coupling of carbon based nanomaterials with light-responsive switches has enabled the fabrication of smart devices for various biological applications, including drug delivery, bioimaging and nanobiosensors. In this review, we highlight the properties of photo-responsive carbon nanomaterials obtained by the conjugation of CNTs and graphene with azobenzenes and spiropyrans molecules to investigate biological systems, devising possible future directions in the field. PMID:29707534

Photo-Responsive Graphene and Carbon Nanotubes to Control and Tackle Biological Systems

NASA Astrophysics Data System (ADS)

Cardano, Francesca; Frasconi, Marco; Giordani, Silvia

2018-04-01

Photo-responsive multifunctional nanomaterials are receiving considerable attention for biological applications because of their unique properties. The functionalization of the surface of carbon nanotubes (CNTs) and graphene, among other carbon based nanomaterials, with molecular switches that exhibit reversible transformations between two or more isomers in response to different kind of external stimuli, such as electromagnetic radiation, temperature and pH, has allowed the control of the optical and electrical properties of the nanomaterial. Light-controlled molecular switches, such as azobenzene and spiropyran, have attracted a lot of attention for nanomaterial’s functionalization because of the remote modulation of their physicochemical properties using light stimulus. The enhanced properties of the hybrid materials obtained from the coupling of carbon based nanomaterials with light-responsive switches has enabled the fabrication of smart devices for various biological applications, including drug delivery, bioimaging and nanobiosensors. In this review, we highlight the properties of photo-responsive carbon nanomaterials obtained by the conjugation of CNTs and graphene with azobenzenes and spiropyrans molecules to investigate biological systems, devising possible future directions in the field.

Unique picoeukaryotic algal community under multiple environmental stress conditions in a shallow, alkaline pan.

PubMed

Pálffy, Károly; Felföldi, Tamás; Mentes, Anikó; Horváth, Hajnalka; Márialigeti, Károly; Boros, Emil; Vörös, Lajos; Somogyi, Boglárka

2014-01-01

Winter phytoplankton communities in the shallow alkaline pans of Hungary are frequently dominated by picoeukaryotes, sometimes in particularly high abundance. In winter 2012, the ice-covered alkaline Zab-szék pan was found to be extraordinarily rich in picoeukaryotic green algae (42-82 × 10(6) cells ml(-1)) despite the simultaneous presence of multiple stressors (low temperature and light intensity with high pH and salinity). The maximum photosynthetic rate of the picoeukaryote community was 1.4 μg C μg chlorophyll a (-1) h(-1) at 125 μmol m(-2) s(-1). The assimilation rates compared with the available light intensity measured on the field show that the community was considerably light-limited. Estimated areal primary production was 180 mg C m(-2) d(-1). On the basis of the 18S rRNA gene analysis (cloning and DGGE), the community was phylogenetically heterogeneous with several previously undescribed chlorophyte lineages, which indicates the ability of picoeukaryotic communities to maintain high genetic diversity under extreme conditions.

The correlation and quantification of airborne spectroradiometer data to turbidity measurements at Lake Powell, Utah

NASA Technical Reports Server (NTRS)

Merry, C. J.

1979-01-01

A water sampling program was accomplished at Lake Powell, Utah, during June 1975 for correlation to multispectral data obtained with a 500-channel airborne spectroradiometer. Field measurements were taken of percentage of light transmittance, surface temperature, pH and Secchi disk depth. Percentage of light transmittance was also measured in the laboratory for the water samples. Analyses of electron micrographs and suspended sediment concentration data for four water samples located at Hite Bridge, Mile 168, Mile 150 and Bullfrog Bay indicated differences in the composition and concentration of the particulate matter. Airborne spectroradiometer multispectral data were analyzed for the four sampling locations. The results showed that: (1) as the percentage of light transmittance of the water samples decreased, the reflected radiance increased; and (2) as the suspended sediment concentration (mg/l) increased, the reflected radiance increased in the 1-80 mg/l range. In conclusion, valuable qualitative information was obtained on surface turbidity for the Lake Powell water spectra. Also, the reflected radiance measured at a wavelength of 0.58 micron was directly correlated to the suspended sediment concentration.

Light-dependent delta pH and membrane potential changes in halobacterial vesicles coupled to sodium transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamo, N.; Racanelli, T.; Packer, L.

1982-01-01

Bacteriorhodopsin and Halorhodopsin present in Halobacterium halobium strains have been investigated in relation to Na/sup +//H/sup +/ exchange in isolated cell envelope vesicles. Upon illumination, these retinal proteins result in extrusion of sodium ions by either an electrogenic Na/sup +//Ha/sup +/ antiporter and/or a direct sodium pump. Since a molecular characterization of these mechanism(s) of sodium extrusion has not yet been realized, it was of interest to measure directly the light- and sodium-dependent changes in delta pH and membrane potential under nearly identical conditions in S9 and R1mR cell membrane vesicles to gain information on the relation of these retinalmore » proteins to sodium extrusion. These activities were evaluated in terms of their dependence on light intensity, and on the inhibitory effect of chemical modifiers of carboxyl groups (carbodiimides); electroneutral exchanges (monensin and triphenyltin); digitoxin and some analogues; and phloretin. Under most of the conditions and treatments employed, light- and sodium-dependent delta pH led to similar effects in both membrane vesicle types. Hence, it is concluded that the delta pH and delta psi which arise from sodium transport occur by either a single mechanism or by one which shares common features.« less

[Effects of simulated acid rain on Quercus glauca seedlings photosynthesis and chlorophyll fluorescence].

PubMed

Li, Jia; Jiang, Hong; Yu, Shu-quan; Jiang, Fu-wei; Yin, Xiu-min; Lu, Mei-juan

2009-09-01

Taking the seedlings of Quercus glauca, a dominant evergreen broadleaf tree species in subtropical area, as test materials, this paper studied their photosynthesis, chlorophyll fluorescence, and chlorophyll content under effects of simulated acid rain with pH 2.5, 4.0, and 5.6 (CK). After 2-year acid rain stress, the net photosynthetic rate of Q. glauca increased significantly with decreasing pH of acid rain. The acid rain with pH 2.5 and 4.0 increased the stomatal conductance and transpiration rate, and the effect was more significant under pH 2.5. The intercellular CO2 concentration decreased in the order of pH 2.5 > pH 5.6 > pH 4.0. The maximum photosynthetic rate, light compensation point, light saturation point, and dark respiration rate were significantly higher under pH 2.5 and 4.0 than under pH 5.6, while the apparent quantum yield was not sensitive to acid rain stress. The maximal photochemical efficiency of PS II and the potential activity of PS II under pH 2.5 and 4.0 were significantly higher than those under pH 5.6. The relative chlorophyll content was in the order of pH 2.5 > pH 5.6 > pH 4.0, and there was a significant difference between pH 2.5 and 4.0. All the results suggested that the photosynthesis and chlorophyll fluorescence of Q. glauca increased under the effects of acid rain with pH 2.5 and 4.0, and the acid rain with pH 2.5 had more obvious effects.

Preparation and characterization of multi stimuli-responsive photoluminescent nanocomposites of graphene quantum dots with hyperbranched polyethylenimine derivatives

NASA Astrophysics Data System (ADS)

Liu, Xing; Liu, Hua-Ji; Cheng, Fa; Chen, Yu

2014-06-01

Oxidized graphene sheets (OGS) were treated with a hyperbranched polyethylenimine (PEI) under hydrothermal conditions to generate nanocomposites of graphene quantum dots (GQDs) functionalized with PEI (GQD-PEIs). The influence of the reaction temperature and the PEI/OGS feed ratio on the photoluminescence properties of the GQD-PEIs was studied. The obtained GQD-PEIs were characterized by TEM, dynamic light scattering, elemental analysis, FTIR, zeta potential measurements and 1H NMR spectroscopy, from which their structural information was inferred. Subsequently, isobutyric amide (IBAm) groups were attached to the GQD-PEIs through the amidation reaction of isobutyric anhydride with the PEI moieties, which resulted in GQD-PEI-IBAm nanocomposites. GQD-PEI-IBAm was not only thermoresponsive, but also responded to other stimuli, including inorganic salts, pH, and loaded organic guests. The cloud point temperature (Tcp) of aqueous solutions of GQD-PEI-IBAm could be modulated through changing the number of IBAm units in GQD-PEI-IBAm, by varying the type and concentration of the inorganic salts and loaded organic guests, or by varying the pH. All the obtained GQD-PEI-IBAm nanocomposites were photoluminescent, and their maximum emission wavelengths were not influenced by outside stimuli. Their emission intensities were influenced a little or negligibly by pH, traditional salting-out anions (Cl- and SO42-), and the relatively polar aspirin guest. However, the traditional salting-in I- anion and the more hydrophobic 1-pyrenebutyric acid (PBA) guest could effectively quench their fluorescence. 2D NOESY 1H NMR spectra verified that GQD-PEI-IBAm accommodated the relatively polar aspirin guest using the PEI-IBAm shell, but adsorbed the relatively hydrophobic PBA guest through the nanographene core. The release rate of the guest encapsulated by the thermoresponsive GQD is different below and above Tcp.Oxidized graphene sheets (OGS) were treated with a hyperbranched polyethylenimine (PEI) under hydrothermal conditions to generate nanocomposites of graphene quantum dots (GQDs) functionalized with PEI (GQD-PEIs). The influence of the reaction temperature and the PEI/OGS feed ratio on the photoluminescence properties of the GQD-PEIs was studied. The obtained GQD-PEIs were characterized by TEM, dynamic light scattering, elemental analysis, FTIR, zeta potential measurements and 1H NMR spectroscopy, from which their structural information was inferred. Subsequently, isobutyric amide (IBAm) groups were attached to the GQD-PEIs through the amidation reaction of isobutyric anhydride with the PEI moieties, which resulted in GQD-PEI-IBAm nanocomposites. GQD-PEI-IBAm was not only thermoresponsive, but also responded to other stimuli, including inorganic salts, pH, and loaded organic guests. The cloud point temperature (Tcp) of aqueous solutions of GQD-PEI-IBAm could be modulated through changing the number of IBAm units in GQD-PEI-IBAm, by varying the type and concentration of the inorganic salts and loaded organic guests, or by varying the pH. All the obtained GQD-PEI-IBAm nanocomposites were photoluminescent, and their maximum emission wavelengths were not influenced by outside stimuli. Their emission intensities were influenced a little or negligibly by pH, traditional salting-out anions (Cl- and SO42-), and the relatively polar aspirin guest. However, the traditional salting-in I- anion and the more hydrophobic 1-pyrenebutyric acid (PBA) guest could effectively quench their fluorescence. 2D NOESY 1H NMR spectra verified that GQD-PEI-IBAm accommodated the relatively polar aspirin guest using the PEI-IBAm shell, but adsorbed the relatively hydrophobic PBA guest through the nanographene core. The release rate of the guest encapsulated by the thermoresponsive GQD is different below and above Tcp. Electronic supplementary information (ESI) available: Elemental analysis data; typical FTIR spectra; typical photographs of the GQD solution before and after phase transition; typical luminescence photographs, and typical photoluminescence spectra. See DOI: 10.1039/c4nr00739e

Prospects for P-bearing molecules in cometary atmospheres

NASA Astrophysics Data System (ADS)

Boice, Daniel; de Almeida, Amaury

Phosphorus is a key element in all known forms of life and phosphorus-bearing compounds have been observed in space. Phosphorus is ubiquitous in meteorites, albeit in small quantities, with phosphates being found in stoney meteorites and phosphides have been identified in iron meteorites. It has been detected as part of the dust component in comet Halley but searches for P-bearing species in the gas phase in comets have been unsuccessful. Based of its moderate cosmic abundance (eighteenth most abundant element, [P]/[N] = 4 x 10-3 ) and the positive identification of P-bearing species in the interstellar medium (such as, PN, PC, HCP and PO), we would expect simple molecules, diatomics (like PH, PO, PC, PS), triatomics (like HCP and PH2 ), and possibly other polyatomics (like phosphine PH3 and diphosphine P2 H4 ), to exist in cometary ices, hence released into the gas phase upon ice sublimation. Our fluid dynamics model with chemistry of cometary comae (SUISEI) has been adapted to study this problem. SUISEI produces cometocentric abundances of the coma gas species; velocities of the bulk gas, light atomic and molecular hydrogen with escape, and electrons; gas and electron temperatures; column densities to facilitate comparison with observations; coma energy budget quantities; attenuation of the solar irradiance; and other quantities that can be related readily to observations. We present results from the first quantitative study of phosphorus-bearing molecules in comets to identify likely species containing phosphorus to aid in future searches for this important element in comets, possibly shedding light on issues of comet formation (time and place) and matters of the prebiotic to biotic evolution of life. Acknowledgements. This work was supported by the NSF Planetary Astronomy Program.

Controlling the Mesostructure Formation within the Shell of Novel Cubic/Hexagonal Phase Cetyltrimethylammonium Bromide-Poly(acrylamide-acrylic acid) Capsules for pH Stimulated Release.

PubMed

Tangso, Kristian J; Patel, Hetika; Lindberg, Seth; Hartley, Patrick G; Knott, Robert; Spicer, Patrick T; Boyd, Ben J

2015-11-11

The self-assembly of ordered structures in mixtures of oppositely charged surfactant and polymer systems has been exploited in various cleaning and pharmaceutical applications and continue to attract much interest since their discovery in the late twentieth century. The ability to control the electrostatic and hydrophobic interactions that dictate the formation of liquid crystalline phases in these systems is advantageous in manipulation of structure and rendering them responsive to external stimuli. Nanostructured capsules comprised of the cationic surfactant, cetyltrimethylammonium bromide (CTAB), and the diblock copolymer poly(acrylamide-acrylic acid) (PAAm-AA) were prepared to assess their potential as pH responsive nanomaterials. Crossed-polarizing light microscopy (CPLM) and small-angle X-ray scattering (SAXS) identified coexisting Pm3n cubic and hexagonal phases at the surfactant-polymer interface. The hydrophobic and electrostatic interactions between the oppositely charged components were studied by varying temperature and solution pH, respectively, and were found to influence the liquid crystalline nanostructure formed. The lattice parameter of the mesophases and the fraction of cubic phase in the system decreased upon heating. Acidic conditions resulted in the loss of the highly ordered structures due to protonation of the carboxylic acid group, and subsequent reduction of attractive forces previously present between the oppositely charged molecules. The rate of release of the model hydrophilic drug, Rhodamine B (RhB), from nanostructured macro-sized capsules significantly increased when the pH of the solution was adjusted from pH 7 to pH 2. This allowed for immediate release of the compound of interest "on demand", opening new options for structured materials with increased functionality over typical layer-by-layer capsules.

The stability of water- and fat-soluble vitamin in dentifrices according to pH level and storage type.

PubMed

Park, Jung-Eun; Kim, Ki-Eun; Choi, Yong-Jun; Park, Yong-Duk; Kwon, Ha-Jeong

2016-02-01

The purpose of this study is to evaluate the vitamin stabilities in dentifrices by analyzing various vitamins according to the level and storage temperature. The stabilities of water- and fat-soluble vitamins were investigated in buffer solution at different pH values (4, 7, 8, 10 and 11) for 14 days and in dentifrices at different pH (7 and 10) for 5 months at two temperature conditions (room and refrigeration temperature) by analyzing the remaining amounts using HPLC methods. In the buffer solution, the stability of vitamins B1 , B6 and C was increased as the pH values increased. Vitamins E and K showed poor stability at pH 4, and vitamin B3 showed poor stability at pH 11. In dentifrices, the storage temperature highly influenced vitamin stability, especially vitamins C and E, but the stabilities of vitamins B1 and C according to pH values did not correspond to the buffer solution tests. Vitamin B group was relatively stable in dentifrices, but vitamin C completely disappeared after 5 months. Vitamin K showed the least initial preservation rates. Vitamins were not detected in commercial dentifrices for adults and detected amounts were less than the advertised contents in dentifrices for children. Copyright © 2015 John Wiley & Sons, Ltd.

Conformal Regge theory

NASA Astrophysics Data System (ADS)

Goncalves, Vasco David Fonseca

The work described in this PhD Thesis focuses on the post-processing of optical fibers and their enhancement as sensing element. Since the majority of sensors presented are based in Fabry-Perot interferometers, an historical overview of this category of optical fiber sensors is firstly presented. This review considers the works published since the early years, in the beginning of the 1980s, until the middle of 2015. The incorporation of microcavities at the tip of a single mode fiber was extensively studied, particularly for the measurement of nitrogen and methane gas pressure. These cavities were fabricated using hollow core silica tubes and a hollow core photonic crystal fiber. Following a different approach, the microcavities were incorporated between two sections of single mode fiber. In this case, the low sensitivity to temperature makes these microcavities highly desirable for the measurement of strain at high temperatures. Competences in post-processing techniques such as the chemical etching and the writing of periodical structures in the fiber core by means of an excimer or a femtosecond laser were also acquired in the course of the PhD programme. One of the works consisted in the design and manufacturing of a double clad optical fiber. The refractive index of the inner cladding was higher than the one of the outer cladding and the core. Thus, light was guided in the inner cladding instead of propagating in the core. This situation was overcome by applying chemical etching, thus removing the inner cladding. The core, surrounded by air, was then able to guide light. Two different applications were found for this fiber, as a temperature sensor and as an optical refractometer. In the last, the optical phase changes with the liquid refractive index. Two different types of fiber Bragg gratings were characterized in strain and temperature. Sensing structures obtained through the phase mask technique at the tip of an optical fiber were subjected to chemical etching. In this case, an excimer laser was used. Extremely thin fiber tips were obtained, with an ultra-high sensitivity to strain. The other technique employed to fabricate the fiber Bragg gratings was the point-by-point femtosecond laser inscription. In this case, the sensing elements are very stable at high temperatures and can be used to measure strain in harsh conditions. The employment of optical fiber lasers as sensing elements was also considered in this Thesis. Two laser cavities were studied, one based on the ring configuration and the other based on a figure-of-eight configuration. From these works, the quality of the laser emission, namely the signal-to-noise ratio, the reduced full-width at half maximum and the stability should be highlighted. These characteristics allowed the measurement of different physical parameters, such as strain, temperature and torsion. Lastly, the possibility to use microspheres as sensing elements was considered. Using the electric arc of a fusion splicer, it is possible to create microspheres at the tip of an optical fiber. Furthermore, with this technique it is chains of microspheres can be obtained, constituting Mach-Zehnder-type interferometers which are sensitive to physical parameters like strain and temperature. The preliminary results obtained by introducing silica microspheres in a support structure are also presented. In this case, the sensors were subjected to temperature variations. All the experimental work was combined with the respective theoretical considerations. Many questions have been raised with the course of this PhD, and there are still some without a definite answer. Thus, new research paths can be followed, having their basis grounded in the configurations here presented.

Analytical Applications of Fluorescent Carbon Dots

NASA Astrophysics Data System (ADS)

Goncalves, Helena Maria Rodrigues

The work described in this PhD Thesis focuses on the post-processing of optical fibers and their enhancement as sensing element. Since the majority of sensors presented are based in Fabry-Perot interferometers, an historical overview of this category of optical fiber sensors is firstly presented. This review considers the works published since the early years, in the beginning of the 1980s, until the middle of 2015. The incorporation of microcavities at the tip of a single mode fiber was extensively studied, particularly for the measurement of nitrogen and methane gas pressure. These cavities were fabricated using hollow core silica tubes and a hollow core photonic crystal fiber. Following a different approach, the microcavities were incorporated between two sections of single mode fiber. In this case, the low sensitivity to temperature makes these microcavities highly desirable for the measurement of strain at high temperatures. Competences in post-processing techniques such as the chemical etching and the writing of periodical structures in the fiber core by means of an excimer or a femtosecond laser were also acquired in the course of the PhD programme. One of the works consisted in the design and manufacturing of a double clad optical fiber. The refractive index of the inner cladding was higher than the one of the outer cladding and the core. Thus, light was guided in the inner cladding instead of propagating in the core. This situation was overcome by applying chemical etching, thus removing the inner cladding. The core, surrounded by air, was then able to guide light. Two different applications were found for this fiber, as a temperature sensor and as an optical refractometer. In the last, the optical phase changes with the liquid refractive index. Two different types of fiber Bragg gratings were characterized in strain and temperature. Sensing structures obtained through the phase mask technique at the tip of an optical fiber were subjected to chemical etching. In this case, an excimer laser was used. Extremely thin fiber tips were obtained, with an ultra-high sensitivity to strain. The other technique employed to fabricate the fiber Bragg gratings was the point-by-point femtosecond laser inscription. In this case, the sensing elements are very stable at high temperatures and can be used to measure strain in harsh conditions. The employment of optical fiber lasers as sensing elements was also considered in this Thesis. Two laser cavities were studied, one based on the ring configuration and the other based on a figure-of-eight configuration. From these works, the quality of the laser emission, namely the signal-to-noise ratio, the reduced full-width at half maximum and the stability should be highlighted. These characteristics allowed the measurement of different physical parameters, such as strain, temperature and torsion. Lastly, the possibility to use microspheres as sensing elements was considered. Using the electric arc of a fusion splicer, it is possible to create microspheres at the tip of an optical fiber. Furthermore, with this technique it is chains of microspheres can be obtained, constituting Mach-Zehnder-type interferometers which are sensitive to physical parameters like strain and temperature. The preliminary results obtained by introducing silica microspheres in a support structure are also presented. In this case, the sensors were subjected to temperature variations. All the experimental work was combined with the respective theoretical considerations. Many questions have been raised with the course of this PhD, and there are still some without a definite answer. Thus, new research paths can be followed, having their basis grounded in the configurations here presented.

Nanostructured Photoanodes for Solar Cells

NASA Astrophysics Data System (ADS)

Apolinario, Arlete Ondina Alves da Silva

The work described in this PhD Thesis focuses on the post-processing of optical fibers and their enhancement as sensing element. Since the majority of sensors presented are based in Fabry-Perot interferometers, an historical overview of this category of optical fiber sensors is firstly presented. This review considers the works published since the early years, in the beginning of the 1980s, until the middle of 2015. The incorporation of microcavities at the tip of a single mode fiber was extensively studied, particularly for the measurement of nitrogen and methane gas pressure. These cavities were fabricated using hollow core silica tubes and a hollow core photonic crystal fiber. Following a different approach, the microcavities were incorporated between two sections of single mode fiber. In this case, the low sensitivity to temperature makes these microcavities highly desirable for the measurement of strain at high temperatures. Competences in post-processing techniques such as the chemical etching and the writing of periodical structures in the fiber core by means of an excimer or a femtosecond laser were also acquired in the course of the PhD programme. One of the works consisted in the design and manufacturing of a double clad optical fiber. The refractive index of the inner cladding was higher than the one of the outer cladding and the core. Thus, light was guided in the inner cladding instead of propagating in the core. This situation was overcome by applying chemical etching, thus removing the inner cladding. The core, surrounded by air, was then able to guide light. Two different applications were found for this fiber, as a temperature sensor and as an optical refractometer. In the last, the optical phase changes with the liquid refractive index. Two different types of fiber Bragg gratings were characterized in strain and temperature. Sensing structures obtained through the phase mask technique at the tip of an optical fiber were subjected to chemical etching. In this case, an excimer laser was used. Extremely thin fiber tips were obtained, with an ultra-high sensitivity to strain. The other technique employed to fabricate the fiber Bragg gratings was the point-by-point femtosecond laser inscription. In this case, the sensing elements are very stable at high temperatures and can be used to measure strain in harsh conditions. The employment of optical fiber lasers as sensing elements was also considered in this Thesis. Two laser cavities were studied, one based on the ring configuration and the other based on a figure-of-eight configuration. From these works, the quality of the laser emission, namely the signal-to-noise ratio, the reduced full-width at half maximum and the stability should be highlighted. These characteristics allowed the measurement of different physical parameters, such as strain, temperature and torsion. Lastly, the possibility to use microspheres as sensing elements was considered. Using the electric arc of a fusion splicer, it is possible to create microspheres at the tip of an optical fiber. Furthermore, with this technique it is chains of microspheres can be obtained, constituting Mach-Zehnder-type interferometers which are sensitive to physical parameters like strain and temperature. The preliminary results obtained by introducing silica microspheres in a support structure are also presented. In this case, the sensors were subjected to temperature variations. All the experimental work was combined with the respective theoretical considerations. Many questions have been raised with the course of this PhD, and there are still some without a definite answer. Thus, new research paths can be followed, having their basis grounded in the configurations here presented.

Chemoselectivity of Immobilized Transition Metal Catalysts

NASA Astrophysics Data System (ADS)

Teixeira, Filipe

The work described in this PhD Thesis focuses on the post-processing of optical fibers and their enhancement as sensing element. Since the majority of sensors presented are based in Fabry-Perot interferometers, an historical overview of this category of optical fiber sensors is firstly presented. This review considers the works published since the early years, in the beginning of the 1980s, until the middle of 2015. The incorporation of microcavities at the tip of a single mode fiber was extensively studied, particularly for the measurement of nitrogen and methane gas pressure. These cavities were fabricated using hollow core silica tubes and a hollow core photonic crystal fiber. Following a different approach, the microcavities were incorporated between two sections of single mode fiber. In this case, the low sensitivity to temperature makes these microcavities highly desirable for the measurement of strain at high temperatures. Competences in post-processing techniques such as the chemical etching and the writing of periodical structures in the fiber core by means of an excimer or a femtosecond laser were also acquired in the course of the PhD programme. One of the works consisted in the design and manufacturing of a double clad optical fiber. The refractive index of the inner cladding was higher than the one of the outer cladding and the core. Thus, light was guided in the inner cladding instead of propagating in the core. This situation was overcome by applying chemical etching, thus removing the inner cladding. The core, surrounded by air, was then able to guide light. Two different applications were found for this fiber, as a temperature sensor and as an optical refractometer. In the last, the optical phase changes with the liquid refractive index. Two different types of fiber Bragg gratings were characterized in strain and temperature. Sensing structures obtained through the phase mask technique at the tip of an optical fiber were subjected to chemical etching. In this case, an excimer laser was used. Extremely thin fiber tips were obtained, with an ultra-high sensitivity to strain. The other technique employed to fabricate the fiber Bragg gratings was the point-by-point femtosecond laser inscription. In this case, the sensing elements are very stable at high temperatures and can be used to measure strain in harsh conditions. The employment of optical fiber lasers as sensing elements was also considered in this Thesis. Two laser cavities were studied, one based on the ring configuration and the other based on a figure-of-eight configuration. From these works, the quality of the laser emission, namely the signal-to-noise ratio, the reduced full-width at half maximum and the stability should be highlighted. These characteristics allowed the measurement of different physical parameters, such as strain, temperature and torsion. Lastly, the possibility to use microspheres as sensing elements was considered. Using the electric arc of a fusion splicer, it is possible to create microspheres at the tip of an optical fiber. Furthermore, with this technique it is chains of microspheres can be obtained, constituting Mach-Zehnder-type interferometers which are sensitive to physical parameters like strain and temperature. The preliminary results obtained by introducing silica microspheres in a support structure are also presented. In this case, the sensors were subjected to temperature variations. All the experimental work was combined with the respective theoretical considerations. Many questions have been raised with the course of this PhD, and there are still some without a definite answer. Thus, new research paths can be followed, having their basis grounded in the configurations here presented.

Sources and diagnostics for attosecond science

NASA Astrophysics Data System (ADS)

Miranda, Miguel Nicolau da Costa Ribeiro de

The work described in this PhD Thesis focuses on the post-processing of optical fibers and their enhancement as sensing element. Since the majority of sensors presented are based in Fabry-Perot interferometers, an historical overview of this category of optical fiber sensors is firstly presented. This review considers the works published since the early years, in the beginning of the 1980s, until the middle of 2015. The incorporation of microcavities at the tip of a single mode fiber was extensively studied, particularly for the measurement of nitrogen and methane gas pressure. These cavities were fabricated using hollow core silica tubes and a hollow core photonic crystal fiber. Following a different approach, the microcavities were incorporated between two sections of single mode fiber. In this case, the low sensitivity to temperature makes these microcavities highly desirable for the measurement of strain at high temperatures. Competences in post-processing techniques such as the chemical etching and the writing of periodical structures in the fiber core by means of an excimer or a femtosecond laser were also acquired in the course of the PhD programme. One of the works consisted in the design and manufacturing of a double clad optical fiber. The refractive index of the inner cladding was higher than the one of the outer cladding and the core. Thus, light was guided in the inner cladding instead of propagating in the core. This situation was overcome by applying chemical etching, thus removing the inner cladding. The core, surrounded by air, was then able to guide light. Two different applications were found for this fiber, as a temperature sensor and as an optical refractometer. In the last, the optical phase changes with the liquid refractive index. Two different types of fiber Bragg gratings were characterized in strain and temperature. Sensing structures obtained through the phase mask technique at the tip of an optical fiber were subjected to chemical etching. In this case, an excimer laser was used. Extremely thin fiber tips were obtained, with an ultra-high sensitivity to strain. The other technique employed to fabricate the fiber Bragg gratings was the point-by-point femtosecond laser inscription. In this case, the sensing elements are very stable at high temperatures and can be used to measure strain in harsh conditions. The employment of optical fiber lasers as sensing elements was also considered in this Thesis. Two laser cavities were studied, one based on the ring configuration and the other based on a figure-of-eight configuration. From these works, the quality of the laser emission, namely the signal-to-noise ratio, the reduced full-width at half maximum and the stability should be highlighted. These characteristics allowed the measurement of different physical parameters, such as strain, temperature and torsion. Lastly, the possibility to use microspheres as sensing elements was considered. Using the electric arc of a fusion splicer, it is possible to create microspheres at the tip of an optical fiber. Furthermore, with this technique it is chains of microspheres can be obtained, constituting Mach-Zehnder-type interferometers which are sensitive to physical parameters like strain and temperature. The preliminary results obtained by introducing silica microspheres in a support structure are also presented. In this case, the sensors were subjected to temperature variations. All the experimental work was combined with the respective theoretical considerations. Many questions have been raised with the course of this PhD, and there are still some without a definite answer. Thus, new research paths can be followed, having their basis grounded in the configurations here presented.

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat

2014-09-03

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied.more » The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.« less

Investigating Block-Copolymer Micelle Dynamics for Tunable Cargo Delivery

NASA Astrophysics Data System (ADS)

Li, Xiuli; Kidd, Bryce; Cooksey, Tyler; Robertson, Megan; Madsen, Louis

Block-copolymer micelles (BCPMs) can carry molecular cargo in a nanoscopic package that is tunable using polymer structure in combination with cargo properties, as well as with external stimuli such as temperature or pH. For example, BCPMs can be used in targeted anticancer drug delivery due to their biocompatibility, in vivo degradability and prolonged circulation time. We are using NMR spectroscopy and diffusometry as well as SANS to investigate BCPMs. Here we study a diblock poly(ethylene oxide)-b-(caprolactone) (PEO-PCL) that forms spherical micelles at 1% (w/v) in the mixed solvent D2O/THF-d8. We quantify the populations and diffusion coefficients of coexisting micelles and free unimers over a range of temperatures and solvent compositions. We use temperature as a stimulus to enhance unimer exchange and hence trigger cargo release, in some cases at a few degrees above body temperature. We present evidence for dominance of the insertion-expulsion mechanism of unimer exchange in these systems, and we map phase diagrams versus temperature and solvent composition. This study sheds light on how intermolecular interactions fundamentally affect cargo release, unimer exchange, and overall micelle tunability.

Stability of the Stevia-Derived Sweetener Rebaudioside A in Solution as Affected by Ultraviolet Light Exposure.

PubMed

Zhang, Jiewen; Bell, Leonard N

2017-04-01

Rebaudioside A is a natural noncaloric high-potency sweetener extracted from the leaves of Stevia rebaudiana. With rebaudioside A use increasing in foods, understanding the factors affecting its stability is necessary. This project evaluated the degradation rate constants of rebaudioside A in water, 0.1 M phosphate buffer, and 0.1 M citrate buffer at pH 3 and 7 as a function of ultraviolet (UV) light intensity (365 nm, 0 μW/cm 2 for dark conditions, 27 μW/cm 2 for low intensity, and 190 μW/cm 2 for high intensity) at 32.5 °C. Rebaudioside A stability was adversely affected by light exposure. The pseudo-1st-order degradation rate constants increased significantly (P < 0.05) with increasing light intensity in all solutions. Under dark conditions, rebaudioside A in phosphate buffers was more susceptible to breakdown than in water and citrate buffers at both pH levels. However, exposure to UV light resulted in rebaudioside A degradation occurring approximately 10 times faster in citrate than in phosphate buffers at both pH levels. The sensitivity of rebaudioside A to UV light was greater in citrate buffers than in water or phosphate buffers. The use of light-protective packaging for beverages containing rebaudioside A will improve its stability. © 2017 Institute of Food Technologists®.

Stability of Secondary and Tertiary Structures of Virus-Like Particles Representing Noroviruses: Effects of pH, Ionic Strength, and Temperature and Implications for Adhesion to Surfaces.

PubMed

Samandoulgou, Idrissa; Hammami, Riadh; Morales Rayas, Rocio; Fliss, Ismail; Jean, Julie

2015-11-01

Loss of ordered molecular structure in proteins is known to increase their adhesion to surfaces. The aim of this work was to study the stability of norovirus secondary and tertiary structures and its implications for viral adhesion to fresh foods and agrifood surfaces. The pH, ionic strength, and temperature conditions studied correspond to those prevalent in the principal vehicles of viral transmission (vomit and feces) and in the food processing and handling environment (pasteurization and refrigeration). The structures of virus-like particles representing GI.1, GII.4, and feline calicivirus (FCV) were studied using circular dichroism and intrinsic UV fluorescence. The particles were remarkably stable under most of the conditions. However, heating to 65°C caused losses of β-strand structure, notably in GI.1 and FCV, while at 75°C the α-helix content of GII.4 and FCV decreased and tertiary structures unfolded in all three cases. Combining temperature with pH or ionic strength caused variable losses of structure depending on the particle type. Regardless of pH, heating to pasteurization temperatures or higher would be required to increase GII.4 and FCV adhesion, while either low or high temperatures would favor GI.1 adhesion. Regardless of temperature, increased ionic strength would increase GII.4 adhesion but would decrease GI.1 adhesion. FCV adsorption would be greater at refrigeration, pasteurization, or high temperature combined with a low salt concentration or at a higher NaCl concentration regardless of temperature. Norovirus adhesion mediated by hydrophobic interaction may depend on hydrophobic residues normally exposed on the capsid surface at pH 3, pH 8, physiological ionic strength, and low temperature, while at pasteurization temperatures it may rely more on buried hydrophobic residues exposed upon structural rearrangement. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Effect of solvent and temperature on the size distribution of casein micelles measured by dynamic light scattering.

PubMed

Beliciu, C M; Moraru, C I

2009-05-01

The objectives of this study were to investigate the effect of the solvent on the accuracy of casein micelle particle size determination by dynamic light scattering (DLS) at different temperatures and to establish a clear protocol for these measurements. Dynamic light scattering analyses were performed at 6, 20, and 50 degrees C using a 90Plus Nanoparticle Size Analyzer (Brookhaven Instruments, Holtsville, NY). Raw and pasteurized skim milk were used as sources of casein micelles. Simulated milk ultrafiltrate, ultrafiltered water, and permeate obtained by ultrafiltration of skim milk using a 10-kDa cutoff membrane were used as solvents. The pH, ionic concentration, refractive index, and viscosity of all solvents were determined. The solvents were evaluated by DLS to ensure that they did not have a significant influence on the results of the particle size measurements. Experimental protocols were developed for accurate measurement of particle sizes in all solvents and experimental conditions. All measurements had good reproducibility, with coefficients of variation below 5%. Both the solvent and the temperature had a significant effect on the measured effective diameter of the casein micelles. When ultrafiltered permeate was used as a solvent, the particle size and polydispersity of casein micelles decreased as temperature increased. The effective diameter of casein micelles from raw skim milk diluted with ultrafiltered permeate was 176.4 +/- 5.3 nm at 6 degrees C, 177.4 +/- 1.9 nm at 20 degrees C, and 137.3 +/- 2.7 nm at 50 degrees C. This trend was justified by the increased strength of hydrophobic bonds with increasing temperature. Overall, the results of this study suggest that the most suitable solvent for the DLS analyses of casein micelles was casein-depleted ultrafiltered permeate. Dilution with water led to micelle dissociation, which significantly affected the DLS measurements, especially at 6 and 20 degrees C. Simulated milk ultrafiltrate seemed to give accurate results only at 20 degrees C. Results obtained in simulated milk ultrafiltrate at 6 degrees C could not be explained based on the known effects of temperature on the casein micelle, whereas at 50 degrees C, precipitation of amorphous calcium phosphate affected the DLS measurement.

Implications of the pH and temperature of diluted, cooled boar semen on fresh and frozen-thawed sperm motility characteristics.

PubMed

Purdy, P H; Tharp, N; Stewart, T; Spiller, S F; Blackburn, H D

2010-10-15

Boar semen is typically collected, diluted and cooled for AI use over numerous days, or frozen immediately after shipping to capable laboratories. The storage temperature and pH of the diluted, cooled boar semen could influence the fertility of boar sperm. Therefore, the purpose of this study was to determine the effects of pH and storage temperature on fresh and frozen-thawed boar sperm motility end points. Semen samples (n = 199) were collected, diluted, cooled and shipped overnight to the National Animal Germplasm Program laboratory for freezing and analysis from four boar stud facilities. The temperature, pH and motility characteristics, determined using computer automated semen analysis, were measured at arrival. Samples were then cryopreserved and post-thaw motility determined. The commercial stud was a significant source of variation for mean semen temperature and pH, as well as total and progressive motility, and numerous other sperm motility characteristics. Based on multiple regression analysis, pH was not a significant source of variation for fresh or frozen-thawed boar sperm motility end points. However, significant models were derived which demonstrated that storage temperature, boar, and the commercial stud influenced sperm motility end points and the potential success for surviving cryopreservation. We inferred that maintaining cooled boar semen at approximately 16 °C during storage will result in higher fresh and frozen-thawed boar sperm quality, which should result in greater fertility. Copyright © 2010 Elsevier Inc. All rights reserved.

Oxidation Behavior of Carbon Steel: Effect of Formation Temperature and pH of the Environment

NASA Astrophysics Data System (ADS)

Dubey, Vivekanand; Kain, Vivekanand

2017-11-01

The nature of surface oxide formed on carbon steel piping used in nuclear power plants affects flow-accelerated corrosion. In this investigation, carbon steel specimens were oxidized in an autoclave using demineralized water at various temperatures (150-300 °C) and at pH levels (neutral, 9.5). At low temperatures (< 240 °C), weight loss of specimens due to dissolution of iron in water occurred to a greater extent than weight gain due to oxide formation. With the increase in temperature, the extent of iron dissolution reduced and weight gain due to oxide formation increased. A similar trend was observed with the increase in pH as was observed with the increase in temperature. XRD and Raman spectroscopy confirmed the formation of magnetite. The oxide film formed by precipitation process was negligible at temperatures from 150 to 240 °C compared to that at higher temperatures (> 240 °C) as confirmed by scanning electron microscopy. Electrochemical impedance measurement followed by Mott-Schottky analysis indicated an increase in defect density with exposure duration at 150 °C at neutral pH but a low and stable defect density in alkaline environment. The defect density of the oxide formed at neutral pH at 150-300 °C was always higher than that formed in alkaline environment as reported in the literature.

Effects of elevated temperature and mobile phase composition on a novel C18 silica column.

PubMed

Lippert, J Andreas; Johnson, Todd M; Lloyd, Jarem B; Smith, Jared P; Johnson, Bryce T; Furlow, Jason; Proctor, Angela; Marin, Stephanie J

2007-05-01

A novel polydentate C18 silica column was evaluated at an elevated temperature under acidic, basic, and neutral mobile phase conditions using ACN and methanol as the mobile phase organic modifier. The temperature range was 40-200 degrees C. The mobile phase compositions were from 0 to 80% organic-aqueous v/v and the mobile phase pH levels were between 2 and 12. The maximum operating temperature of the column was affected by the amount and type of organic modifier used in the mobile phase. Under neutral conditions, the column showed good column thermal stability at temperatures ranging between 120 and 200 degrees C in methanol-water and ACN-water solvent systems. At pH 2 and 3, the column performed well up to about 160 degrees C at two fixed ACN-buffer compositions. Under basic conditions at elevated temperatures, the column material deteriorated more quickly, but still remained stable up to 100 degrees C at pH 9 and 60 degrees C at pH 10. The results of this study indicate that this novel C18 silica-based column represents a significant advancement in RPLC column technology with enhanced thermal and pH stability when compared to traditional bonded phase silica columns.

A monitor for continuous measurement of temperature, pH, and conductance of wet precipitation: Preliminary results from the Adirondack Mountains, New York

USGS Publications Warehouse

Johnsson, P.A.; Reddy, M.M.

1990-01-01

This report describes a continuous wet-only precipitation monitor designed by the U.S. Geological Survey to record variations in rainfall temperature, pH, and specific conductance at 1-min intervals over the course of storms. Initial sampling in the Adirondack Mountains showed that rainfall acidity varied over the course of summer storms, with low initial pH values increasing as storm intensity increased.This report describes a continuous wet-only precipitation monitor designed by the U.S. Geological Survey to record variations in rainfall temperature, pH, and specific conductance at 1-min intervals over the course of storms. Initial sampling in the Adirondack Mountains showed that rainfall acidity varied over the course of summer storms, with low initial pH values increasing as storm intensity increased.

Nickel removal by biosorption onto medlar male flowers coupled with photocatalysis on the spinel ZnMn2O4

PubMed Central

2014-01-01

Ni2+ is a highly toxic above 0.07 mg/L and its removal is of high significance. The biosorption of Ni2+ onto medlar male flowers (MMF) was studied in relation with the physical parameters like pH, contact time, biosorbent dosage, Ni2+ concentration and temperature. The interaction biosorbent-Ni2+ was examined by the FTIR technique. The equilibrium was achieved within 40 min and the data were well fitted by the Langmuir and Redlich-Peterson (R-P) models. The maximum Ni2+ uptake capacity was 17.073 mg/g at 25°C and the Ni2+ removal follows a pseudo-second order kinetic with activation energy of 13.3 kJ/mol. The thermodynamic parameters: ΔS°, ΔH° and ΔG° showed that the biosorption was spontaneous and endothermic. MMF was used as a post treatment technique and the biosorption was coupled with the visible light driven Ni2+ reduction over the spinel ZnMn2O4. The effect of the pH, ZnMn2O4 loading and light intensity on the photoactivity was investigated. 77.5% of Ni2+ was reduced after ~140 min under optimal conditions. The Ni2+ removal reached a rate conversion of 96% of with the coupled system biosorption/photocatalysis is very promising for the water treatment. PMID:24401700

Influence of pH, Salt and Temperature on Pressure Inactivation of Hepatitis A virus

USDA-ARS?s Scientific Manuscript database

The effects of pH (3-7), NaCl (0-6%), and temperature on pressure inactivation of hepatitis A virus (HAV) were determined. The HAV samples were treated at 400 MPa for 1 min at 5, 20, and 50C. Decreasing solution pH enhanced pressure inactivation of HAV. This enhanced inactivation effect was most e...

Influence of daylight on the fate of silver and zinc oxide nanoparticles in natural aquatic environments.

PubMed

Odzak, Niksa; Kistler, David; Sigg, Laura

2017-07-01

Nanoparticles, such as silver (Ag-NP) and zinc oxide (ZnO-NP), are increasingly used in many consumer products. These nanoparticles (NPs) will likely be exposed to the aquatic environment (rain, river, lake water) and to light (visible and UV) in the products where they are applied, or after those products are discharged. Dissolution of Ag-NP and ZnO-NP is an important process because the dissolved Ag + and Zn 2+ are readily available and toxic for aquatic organisms. The objective of this study was to investigate the role of daylight (UV and visible) for the fate of engineered Ag-NP and ZnO-NPs in different types of natural waters. Ag-NP and ZnO-NP were exposed to rainwater, river Rhine, and lake waters (Greifen, Lucerne, Cristallina, Gruère) under different light conditions (no light, UV 300-400 nm and visible light 400-700 nm) for up to 8 days. Stronger agglomeration of Ag-NP was observed in the waters with higher ionic strength in comparison to those with lower ionic strength. Visible light tended to increase the dissolution of Ag-NP under most natural water conditions in comparison to dark conditions, whereas UV-light led to decreased dissolved Ag + after longer exposure time. These effects illustrate the dynamic interactions of Ag-NP with light, which may lead both to increased oxidation and to increased reduction of Ag + by organic compounds under UV-light. In the case of ZnO-NP, agglomeration occurred at higher ionic strength, but the effects of pH were predominant for dissolution, which occurred up to concentrations close to the solubility limit of ZnO(s) at pH around 8.2 and to nearly complete dissolution of ZnO-NP at lower pH (pH 4.8-6.5), with both visible and UV-light facilitating dissolution. This study thus shows that light conditions play an important role in the dissolution processes of nanoparticles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thermal relaxation behavior of residual stress in laser hardened 17-4PH steel after shot peening treatment

NASA Astrophysics Data System (ADS)

Wang, Zhou; Chen, Yanhua; Jiang, Chuanhai

2011-09-01

In order to investigate the residual stress relaxations of shot peened layer, isothermal annealing treatments were carried out on tempered and laser hardened 17-4PH steel after shot peening with different temperatures from 300 °C to 600 °C. The results showed that the residual stresses were relaxed in the whole deformation layer especially under higher temperature. The maximum rates of stress relaxation took place at the initial stage of annealing process in all conditions. The relaxation process during isothermal annealing could be described by Zener-Wert-Avrami function. The thermal stability of residual stress in tempered 17-4PH was higher than that in laser hardened 17-4PH as well as that in α-iron, which was due to the pinning effects of ɛ-Cu precipitates on the dislocation movement. As massive ɛ-Cu precipitates formed in the temperature about 480 °C, the activation enthalpies for stress relaxation in laser hardened 17-4PH were the same as that in tempered 17-4PH in the conditions of isothermal annealing temperatures of 500 °C and 600 °C.

Characterization of polyphenol oxidase from the Manzanilla cultivar (Olea europaea pomiformis) and prevention of browning reactions in bruised olive fruits.

PubMed

Segovia-Bravo, Kharla A; Jarén-Galan, Manuel; García-García, Pedro; Garrido-Fernandez, Antonio

2007-08-08

The crude extract of the polyphenol oxidase (PPO) enzyme from the Manzanilla cultivar (Olea europaea pomiformis) was obtained, and its properties were characterized. The browning reaction followed a zero-order kinetic model. Its maximum activity was at pH 6.0. This activity was completely inhibited at a pH below 3.0 regardless of temperature; however, in alkaline conditions, pH inhibition depended on temperature and was observed at values above 9.0 and 11.0 at 8 and 25 degrees C, respectively. The thermodynamic parameters of substrate oxidation depended on pH within the range in which activity was observed. The reaction occurred according to an isokinetic system because pH affected the enzymatic reaction rate but not the energy required to carry out the reaction. In the alkaline pH region, browning was due to a combination of enzymatic and nonenzymatic reactions that occurred in parallel. These results correlated well with the browning behavior observed in intentionally bruised fruits at different temperatures and in different storage solutions. The use of a low temperature ( approximately 8 degrees C) was very effective for preventing browning regardless of the cover solution used.

Environmental Monitoring of Microbe Metabolic Transformation

NASA Technical Reports Server (NTRS)

Bebout, Brad (Inventor); Fleming, Erich (Inventor); Piccini, Matthew (Inventor); Beasley, Christopher (Inventor); Bebout, Leslie (Inventor)

2013-01-01

Mobile system and method for monitoring environmental parameters involved in growth or metabolic transformation of algae in a liquid. Each of one or more mobile apparati, suspended or partly or wholly submerged in the liquid, includes at least first and second environmental sensors that sense and transmit distinct first and second environmental, growth or transformation parameter values, such as liquid temperature, temperature of gas adjacent to and above the exposed surface, liquid pH, liquid salinity, liquid turbidity, O.sub.2 dissolved in the liquid, CO.sub.2 contained in the liquid, oxidization and reduction potential of the liquid, nutrient concentrations in the liquid, nitrate concentration in the liquid, ammonium concentration in the liquid, bicarbonate concentration in the liquid, phosphate concentration in the liquid, light intensity at the liquid surface, electrical conductivity of the liquid, and a parameter.alpha.(alga) associated with growth stage of the alga, using PAM fluorometry or other suitable parameter measurements.

Xanthan Gum-a lyotropic, liquid crystalline polymer and its properties as a suspending agent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salamone, J.C.; Clough, S.B.; Jamison, D.E.

1982-08-01

Studies a variety of xanthan solutions of various polymer concentrations in the presence and absence of various salts under a polarized light microscope (100X) in order to test xanthan gum for liquid crystalline order. Xanthan gum, a polysaccharide used in drilling fluids and in tertiary recovery, has relatively stable viscosity properties as a function of salt concentration, pH, temperature, and shear degradation. With solutions from 2 to 10% (wt/vol) xanthan gum in distilled water at room temperature, birefringent, ordered domains were observed at 10% concentration, with a decrease in birefringence as the polymer concentration decreased. When the xanthan solution ismore » sheared between a glass slide and a cover slip, the optic axis (chain direction) aligns using the shear direction (as determined by the colors displayed using a first-order red plate). Examines liquid crystalline behavior of other naturally occurring polymers.« less

Investigating new activators for small-bandgap LaX3 (X = Br, I) scintillators

NASA Astrophysics Data System (ADS)

Rutstrom, Daniel; Collette, Robyn; Stand, Luis; Loyd, Matthew; Wu, Yuntao; Koschan, Merry; Melcher, Charles L.; Zhuravleva, Mariya

2018-02-01

Luminescence and scintillation properties of Bi3+, Sb3+, and Eu2+-doped LaI3 and LaBr3 were explored. Out of the three dopants investigated, Eu2+ was the most promising new activator for small-bandgap LaX3 (X = Br, I) and was further studied in the mixed-halide LaBr3-xIx. Crystals were grown from the melt using the vertical Bridgman method. LaBr3:Eu2+ 0.5% (mol) had the most favorable scintillation properties with a light output of 43,000 ph/MeV and 6% energy resolution at 662 keV. Performance of LaBr3-xIx:Eu2+ worsened for most samples as iodide concentration was increased. Room-temperature scintillation of LaI3:Eu2+ 0.1% and 0.5% was observed and is the first case of room-temperature emission reported for doped LaI3.

The impact of environmental factors on carbon dioxide fixation by microalgae.

PubMed

Morales, Marcia; Sánchez, León; Revah, Sergio

2018-02-01

Microalgae are among the most productive biological systems for converting sunlight into chemical energy, which is used to capture and transform inorganic carbon into biomass. The efficiency of carbon dioxide capture depends on the cultivation system configuration (photobioreactors or open systems) and can vary according to the state of the algal physiology, the chemical composition of the nutrient medium, and environmental factors such as irradiance, temperature and pH. This mini-review is focused on some of the most important environmental factors determining photosynthetic activity, carbon dioxide biofixation, cell growth rate and biomass productivity by microalgae. These include carbon dioxide and O2 concentrations, light intensity, cultivation temperature and nutrients. Finally, a review of the operation of microalgal cultivation systems outdoors is presented as an example of the impact of environmental conditions on biomass productivity and carbon dioxide fixation. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Short communication: Urea hydrolysis in dairy cattle manure under different temperature, urea, and pH conditions.

PubMed

Moraes, L E; Burgos, S A; DePeters, E J; Zhang, R; Fadel, J G

2017-03-01

The objective of the study was to quantify the rate of urea hydrolysis in dairy cattle manure under different initial urea concentration, temperature, and pH conditions. In particular, by varying all 3 factors simultaneously, the interactions between them could also be determined. Fresh feces and artificial urine solutions were combined into a slurry to characterize the rate of urea hydrolysis under 2 temperatures (15°C and 35°C), 3 urea concentrations in urine solutions (500, 1,000, and 1,500 mg of urea-N/dL), and 3 pH levels (6, 7, and 8). Urea N concentration in slurry was analyzed at 0.0167, 1, 2, 4, 6, 8, 12, 16, 20, and 24 h after initial mixing. A nonlinear mixed effects model was used to determine the effects of urea concentration, pH, and temperature treatments on the exponential rate of urea hydrolysis and to predict the hydrolysis rate for each treatment combination. We detected a significant interaction between pH and initial urea level. Increasing urea concentration from 1,000 to 1,500 mg of urea-N/dL decreased the rate of urea hydrolysis across all pH levels. Across all pH and initial urea levels, the rate of urea hydrolysis increased with temperature, but the effect of pH was only observed for pH 6 versus pH 8 at the intermediate initial urea concentration. The fast rates of urea hydrolysis indicate that urea was almost completely hydrolyzed within a few hours of urine mixing with feces. The estimated urea hydrolysis rates from this study are likely maximum rates because of the thorough mixing before each sampling. Although considerable mixing of feces and urine occurs on the barn floor of commercial dairy operations from cattle walking through the manure, such mixing may be not as quick and thorough as in this study. Consequently, the urea hydrolysis rates from this study indicate the maximum loss of urea and should be accounted for in management aimed at mitigating ammonia emissions from dairy cattle manure under similar urea concentration, pH, and temperature conditions reported in this experiment. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Validation of a portable, waterproof blood pH analyser for elasmobranchs

PubMed Central

Bouyoucos, Ian A.; Shipley, Oliver; Rummer, Jodie L.; Mandelman, John W.; Brooks, Edward J.; Grubbs, R. Dean

2017-01-01

Abstract Quantifying changes in blood chemistry in elasmobranchs can provide insights into the physiological insults caused by anthropogenic stress, and can ultimately inform conservation and management strategies. Current methods for analysing elasmobranch blood chemistry in the field are often costly and logistically challenging. We compared blood pH values measured using a portable, waterproof pH meter (Hanna Instruments HI 99161) with blood pH values measured by an i-STAT system (CG4+ cartridges), which was previously validated for teleost and elasmobranch fishes, to gauge the accuracy of the pH meter in determining whole blood pH for the Cuban dogfish (Squalus cubensis) and lemon shark (Negaprion brevirostris). There was a significant linear relationship between values derived via the pH meter and the i-STAT for both species across a wide range of pH values and temperatures (Cuban dogfish: 6.8–7.1 pH 24–30°C; lemon sharks: 7.0–7.45 pH 25–31°C). The relative error in the pH meter's measurements was ~±2.7%. Using this device with appropriate correction factors and consideration of calibration temperatures can result in both a rapid and accurate assessment of whole blood pH, at least for the two elasmobranch species examined here. Additional species should be examined in the future across a wide range of temperatures to determine whether correction factors are universal. PMID:28616238

Influence of prebiotics on Lactobacillus reuteri death kinetics under sub-optimal temperatures and pH.

PubMed

Altieri, Clelia; Iorio, Maria Clara; Bevilacqua, Antonio; Sinigaglia, Milena

2016-01-01

Eaten foodstuffs are usually fortified with prebiotic ingredients, such as inulin and oligofructose (FOS). The main goal of this study was to evaluate the combined effects of inulin and FOS with either suboptimal pH or storage temperature on the viability of Lactobacillus reuteri DSM 20016. Data were modeled through Weibull equation for the evaluation of the microbiological shelf life and the survival time. Prebiotics enhanced the microbiological shelf life and enhanced the survival time of the target bacterium. The use of the factorial ANOVA highlighted that inulin and FOS exerted a different effect as a function of pH and temperature. Inulin prolonged survival time under acidic conditions, while the effect of glucose + FOS was significant at pH 8. Finally, temperature could act by increasing or decreasing the effect of prebiotics, as they could exert a protective effect at 30 °C but not at 44 °C. As the main output of this research, we could suggest that the effect of prebiotics on L. reuteri could be significantly affected by pH and temperature, thus pinpointing that the design of a symbiotic food should also rely on these factors.

Role of biogenic amines in the post-mortem migration of Anisakis pegreffii (Nematoda: Anisakidae Dujardin, 1845) larvae into fish fillets.

PubMed

Šimat, Vida; Miletić, Jelena; Bogdanović, Tanja; Poljak, Vedran; Mladineo, Ivona

2015-12-02

Infective third-stage larvae (L3) of nematode Anisakis spp. have been recognized as one of the major food-borne threats in lightly processed fish products in Europe, particularly in the Mediterranean region. Therefore, the effect of different storage temperatures of fish on larval post-mortem migration from visceral cavity into fillets is an important parameter to take into account when evaluating the risk for consumer safety. The European anchovy (Engraulis encrasicolus) were caught during fishing season, a subsample of fillets was checked for the presence of Anisakis larvae at capture (mean abundance=0.07), and the rest was stored at four different temperatures (-18, 0, 4 and 22°C) in order to count migrating larvae and measure the production of biogenic amines over a period of time. Larvae were identified by morphological features and molecular tools. Post-mortem migration was observed in fillets stored at 0 and 4°C after three and five days, respectively, but not at 22 and -18°C. In case of storage at 22°C for two days, at the onset of putrefaction of the visceral organs, larvae migrated out of the visceral cavity towards the fish surface. Measured pH and biogenic amine profile during storage indicated that certain biochemical conditions trigger larval migration into fillets. Likewise, migration was observed at pH ~6.4 when sensory degradation of the fish was markedly visible. Although larval migration was delayed for approximately four days at a temperature of <4°C the correlation between pH and abundance of A. pegreffii larvae in the fillet was high and statistically significant at both 0 (r=0.998, p<0.01) and 4°C (r=0.946, p<0.05). Out of eight biogenic amines measured, cadaverine and putrescine levels correlated the most with the post-mortem migration at 4°C, while tyramine levels were significant at both temperatures. Copyright © 2015 Elsevier B.V. All rights reserved.

Jupiter Climatological Database from Frequent 5-25 µm Mid-IR Spectral Mapping using IRTF/TEXES

NASA Astrophysics Data System (ADS)

Fletcher, Leigh N.; Orton, Glenn S.; Greathouse, Thomas K.; Sinclair, James; Irwin, Patrick G. J.; Giles, Rohini S.; Encrenaz, Therese; Drossart, Pierre

2015-11-01

We report on the development of a long-term Jovian Climatological Database (JCliD) to explore variability in Jupiter’s atmospheric temperatures, winds, clouds and composition- from long-term seasonal changes to short-term major upheavals. Radiometrically calibrated spectral scan maps of Jupiter have been regularly obtained using the TEXES instrument (Texas Echelon cross Echelle Spectrograph, Lacy et al. 2002, PASP 114, p153-168) between 2012 and 2015. Ten settings between 5 and 25 µm (10-20 cm-1 wide settings at spectral resolutions of 2000-10000) were selected to be sensitive to jovian temperatures (via H2, CH4 and CH3D), tropospheric phosphine and ammonia, tropospheric haze opacity and stratospheric hydrocarbons ethane and acetylene. Diffraction-limited spatial resolutions of 0.6-1.6” were achieved. Observations over consecutive nights allow the creation of full spatial maps for comparison with the visible light record, revealing ephemeral stratospheric wave activity, NEB hotspots, heating at the northern auroral oval, and complex thermal signatures associated with tropospheric vortices, waves and barges. Full spectra are inverted via the NEMESIS retrieval algorithm (Irwin et al., 2008, JSQRT 109, p1136-1150) to map temperatures at multiple altitudes (1-600 mbar), winds, aerosol opacity and gaseous composition. The spatial and spectral resolutions of the resulting maps surpass those obtained during the Cassini flyby of Jupiter in 2000, and permit temporal interpolation to understand the environmental conditions related to the emergence and evolution of discrete features. In December 2014 we find warmer temperatures in the northern stratosphere (a seasonal effect in late northern summer despite Jupiter’s small axial tilt); a hemispheric asymmetry in the tropospheric PH3 distribution due to variations in the vigour of vertical mixing and photolytic shielding; elevated PH3, aerosols and NH3 in the equatorial zone (EZ) related to equatorial uplift; elevated aerosol opacity in the northern and southern tropical zones (NTrZ and STrZ); and enhanced PH3 and aerosols over the Great Red Spot. Maps of retrieved properties will be assembled as a database (JCliD) to aid in the interpretation of Juno data during 2016-2017.

Final report of the key comparison APMP.QM-K9: APMP comparison on pH measurement of phosphate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Ohata, Masaki; Cherdchu, Chainarong; Tangpaisarnkul, Nongluck

2011-01-01

The APMP.QM-K9 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a phosphate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan, NMIJ, and the National Institute of Metrology of Thailand, NIMT, in August 2009. After approval by TCQM, the comparison has been conducted by NMIJ and NIMT. The comparison is a key comparison following CCQM-K9, CCQM-K9.1 and CCQM-K9.2. The comparison material was a phosphate buffer of pH around 6.86 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the first APMP key comparison on pH measurement and the third APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004 and APMP.QM-P09 (a phthalate buffer) in 2006. The results can be used further by any participant to support its CMC claim for a phosphate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the temperature(s) used or the full temperature range between 15 °C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Preparation and Cross-Linking of All-Acrylamide Diblock Copolymer Nano-Objects via Polymerization-Induced Self-Assembly in Aqueous Solution

PubMed Central

2017-01-01

Various carboxylic acid-functionalized poly(N,N-dimethylacrylamide) (PDMAC) macromolecular chain transfer agents (macro-CTAs) were chain-extended with diacetone acrylamide (DAAM) by reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization at 70 °C and 20% w/w solids to produce a series of PDMAC–PDAAM diblock copolymer nano-objects via polymerization-induced self-assembly (PISA). TEM studies indicate that a PDMAC macro-CTA with a mean degree of polymerization (DP) of 68 or higher results in the formation of well-defined spherical nanoparticles with mean diameters ranging from 40 to 150 nm. In contrast, either highly anisotropic worms or polydisperse vesicles are formed when relatively short macro-CTAs (DP = 40–58) are used. A phase diagram was constructed to enable accurate targeting of pure copolymer morphologies. Dynamic light scattering (DLS) and aqueous electrophoresis studies indicated that in most cases these PDMAC–PDAAM nano-objects are surprisingly resistant to changes in either solution pH or temperature. However, PDMAC40–PDAAM99 worms do undergo partial dissociation to form a mixture of relatively short worms and spheres on adjusting the solution pH from pH 2–3 to around pH 9 at 20 °C. Moreover, a change in copolymer morphology from worms to a mixture of short worms and vesicles was observed by DLS and TEM on heating this worm dispersion to 50 °C. Postpolymerization cross-linking of concentrated aqueous dispersions of PDMAC–PDAAM spheres, worms, or vesicles was performed at ambient temperature using adipic acid dihydrazide (ADH), which reacts with the hydrophobic ketone-functionalized PDAAM chains. The formation of hydrazone groups was monitored by FT-IR spectroscopy and afforded covalently stabilized nano-objects that remained intact on exposure to methanol, which is a good solvent for both blocks. Rheological studies indicated that the cross-linked worms formed a stronger gel compared to linear precursor worms. PMID:28260814

Heat-induced gelation of casein micelles in aqueous suspensions at different pH.

PubMed

Thomar, Peggy; Nicolai, Taco

2016-10-01

Heat-induced gelation of casein micelles in aqueous solution was investigated between pH 5.2 and pH 6.7 over a wide range of protein concentrations (C=25-160gL(-1)). For C≥40gL(-1) the casein micelles rapidly formed a self-supporting gel above a critical temperature (Tc). At C=160gL(-1), Tc decreased from 90°C at pH 6.5 to 30°C at pH 5.4 and increased with decreasing protein concentration. Oscillatory shear measurements during heating showed that the elastic modulus (Gel) of the gels increased strongly with increasing protein concentration, but was insensitive to the pH and the heating temperature except close to Tc where Gel decreased sharply with decreasing temperature. The microstructure of the gels was observed by confocal scanning laser microscopy. Heat-induced gelation of casein micelles was compared with that of sodium caseinate solutions free of calcium phosphate. Copyright © 2016 Elsevier B.V. All rights reserved.

The vulvar skin microenvironment: influence of different panty liners on temperature, pH and microflora.

PubMed

Runeman, Bo; Rybo, Göran; Forsgren-Brusk, Ulla; Larkö, Olle; Larsson, Peter; Faergemann, Jan

2004-01-01

The aim of this study was to confirm findings that vapour-impermeable panty liners might impair skin climate, and to assess their impact on the skin microflora. Temperature, surface pH and aerobic microflora were measured on vulvar skin of 102 women. The mean skin temperature was 1.1 degrees C higher when using a vapour-impermeable panty liner compared with not using one. Use of panty liners with vapour-permeable back sheets and acidic cores resulted in skin temperature, pH and microflora levels that were very close to those observed in persons not using liners. The temperature, pH and total number of microorganisms were significantly lower for users of vapour-permeable panty liners than for users of vapour-impermeable ones (p <0.05, p<0.001 and p<0.001, respectively). The microorganism densities were usually higher when using the vapour-impermeable panty liner, but mean differences were minor. The use of panty liners seems not to imply a microbial risk for normal, healthy women.

Feasibility of Coupling Between a Single-Mode Elliptical-Core Fiber and a Single Mode Rib Waveguide Over Temperature. Ph.D. Thesis - Akron Univ., Aug. 1995

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.

1995-01-01

To determine the feasibility of coupling the output of an optical fiber to a rib waveguide in a temperature environment ranging from 20 C to 300 C, a theoretical calculation of the coupling efficiency between the two was investigated. This is a significant problem which needs to be addressed to determine whether an integrated optic device can function in a harsh temperature environment. Because the behavior of the integrated-optic device is polarization sensitive, a polarization-preserving optic fiber, via its elliptical core, was used to couple light with a known polarization into the device. To couple light energy efficiently from an optical fiber into a channel waveguide, the design of both components should provide for well-matched electric field profiles. The rib waveguide analyzed was the light input channel of an integrated-optic pressure sensor. Due to the complex geometry of the rib waveguide, there is no analytical solution to the wave equation for the guided modes. Approximation or numerical techniques must be utilized to determine the propagation constants and field patterns of the guide. In this study, three solution methods were used to determine the field profiles of both the fiber and guide: the effective-index method (EIM), Marcatili's approximation, and a Fourier method. These methods were utilized independently to calculate the electric field profile of a rib channel waveguide and elliptical fiber at two temperatures, 20 C and 300 C. These temperatures were chosen to represent a nominal and a high temperature that the device would experience. Using the electric field profile calculated from each method, the theoretical coupling efficiency between the single-mode optical fiber and rib waveguide was calculated using the overlap integral and results of the techniques compared. Initially, perfect alignment was assumed and the coupling efficiency calculated. Then, the coupling efficiency calculation was repeated for a range of transverse offsets at both temperatures. Results of the calculation indicate a high coupling efficiency can be achieved when the two components were properly aligned. The coupling efficiency was more sensitive to alignment offsets in the y direction than the x, due to the elliptical modal profile of both components. Changes in the coupling efficiency over temperature were found to be minimal.

A miniature integrated multimodal sensor for measuring pH, EC and temperature for precision agriculture.

PubMed

Futagawa, Masato; Iwasaki, Taichi; Murata, Hiroaki; Ishida, Makoto; Sawada, Kazuaki

2012-01-01

Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to be done in small localized areas. We have fabricated a multimodal sensor on a small Si chip in which a pH sensor was integrated with electrical conductivity (EC) and temperature sensors. An ISFET with a Si(3)N(4) membrane was used for the pH sensor. For the EC sensor, the electrical conductivity between platinum electrodes was measured, and the temperature sensor was a p-n junction diode. These are some of the most important measurements required for controlling the conditions in plant beds. The multimodal sensor can be inserted into a plant bed for in situ monitoring. To confirm the absence of crosstalk between the sensors, we made simultaneous measurements of pH, EC, and temperature of a pH buffer solution in a plant bed. When the solution was diluted with hot or cold water, the real time measurements showed changes to the EC and temperature, but no change in pH. We also demonstrated that our sensor was capable of simultaneous in situ measurements in rock wool without being affected by crosstalk.

A Miniature Integrated Multimodal Sensor for Measuring pH, EC and Temperature for Precision Agriculture

PubMed Central

Futagawa, Masato; Iwasaki, Taichi; Murata, Hiroaki; Ishida, Makoto; Sawada, Kazuaki

2012-01-01

Making several simultaneous measurements with different kinds of sensors at the same location in a solution is difficult because of crosstalk between the sensors. In addition, because the conditions at different locations in plant beds differ, in situ measurements in agriculture need to be done in small localized areas. We have fabricated a multimodal sensor on a small Si chip in which a pH sensor was integrated with electrical conductivity (EC) and temperature sensors. An ISFET with a Si3N4 membrane was used for the pH sensor. For the EC sensor, the electrical conductivity between platinum electrodes was measured, and the temperature sensor was a p-n junction diode. These are some of the most important measurements required for controlling the conditions in plant beds. The multimodal sensor can be inserted into a plant bed for in situ monitoring. To confirm the absence of crosstalk between the sensors, we made simultaneous measurements of pH, EC, and temperature of a pH buffer solution in a plant bed. When the solution was diluted with hot or cold water, the real time measurements showed changes to the EC and temperature, but no change in pH. We also demonstrated that our sensor was capable of simultaneous in situ measurements in rock wool without being affected by crosstalk. PMID:22969403

Determining pH at elevated pressure and temperature using in situ ¹³C NMR.

PubMed

Surface, J Andrew; Wang, Fei; Zhu, Yanzhe; Hayes, Sophia E; Giammar, Daniel E; Conradi, Mark S

2015-02-03

We have developed an approach for determining pH at elevated pressures and temperatures by using (13)C NMR measurements of inorganic carbon species together with a geochemical equilibrium model. The approach can determine in situ pH with precision better than 0.1 pH units at pressures, temperatures, and ionic strengths typical of geologic carbon sequestration systems. A custom-built high pressure NMR probe was used to collect (13)C NMR spectra of (13)C-labeled CO2 reactions with NaOH solutions and Mg(OH)2 suspensions at pressures up to 107 bar and temperatures of 80 °C. The quantitative nature of NMR spectroscopy allows the concentration ratio [CO2]/[HCO3(-)] to be experimentally determined. This ratio is then used with equilibrium constants calculated for the specific pressure and temperature conditions and appropriate activity coefficients for the solutes to calculate the in situ pH. The experimentally determined [CO2]/[HCO3(-)] ratios agree well with the predicted values for experiments performed with three different concentrations of NaOH and equilibration with multiple pressures of CO2. The approach was then applied to experiments with Mg(OH)2 slurries in which the change in pH could track the dissolution of CO2 into solution, rapid initial Mg(OH)2 dissolution, and onset of magnesium carbonate precipitation.

Removal Efficiency of the Heavy Metals Zn(II), Pb(II) and Cd(II) by Saprolegnia delica and Trichoderma viride at Different pH Values and Temperature Degrees

PubMed Central

Hashem, Mohamed

2007-01-01

The removal efficiency of the heavy metals Zn, Pb and Cd by the zoosporic fungal species Saprolegnia delica and the terrestrial fungus Trichoderma viride, isolated from polluted water drainages in the Delta of Nile in Egypt, as affected by various ranges of pH values and different temperature degrees,was extensively investigated. The maximum removal efficiency of S. delica for Zn(II) and Cd(II) was obtained at pH 8 and for Pb(II) was at pH 6 whilst the removal efficiency of T. viride was found to be optimum at pH 6 for the three applied heavy metals. Regardless the median lethal doses of the three heavy metals, Zn recorded the highest bioaccumulation potency by S. delica at all pH values except at pH 4, followed by Pb whereas Cd showed the lowest removal potency by the fungal species and vice versa in case of T. viride. The optimum biomass dry weight production by S. delica was found when the fungus was grown in the medium treated with the heavy metal Pb at pH 6, followed by Zn at pH 8 and Cd at pH 8. The optimum biomass dry weight yield by T. viride amended with Zn,Pb and Cd was obtained at pH 6 for the three heavy metals with the maximum value at Zn. The highest yield of biomass dry weight was found when T. viride treated with Cd at all different pH values followed by Pb whilst Zn output was the lowest and this result was reversed in case of S. delica. The maximum removal efficiency and the biomass dry weight production for the three tested heavy metals was obtained at the incubation temperature 20℃ in case of S. delica while it was 25℃ for T. viride. Incubation of T. viride at higher temperatures (30℃ and 35℃) enhanced the removal efficiency of Pb and Cd than low temperatures (15℃ and 20℃) and vice versa in case of Zn removal. At all tested incubation temperatures, the maximum yield of biomass dry weight was attained at Zn treatment by the two tested fungal species. The bioaccumulation potency of S. delica for Zn was higher than that for Pb at all temperature degrees of incubation and Cd bioaccumulation was the lowest whereas T. viride showed the highest removal efficiency for Pb followed by Cd and Zn was the minor of the heavy metals. PMID:24015084

The impact of morning light intensity and environmental temperature on body temperatures and alertness.

PubMed

Te Kulve, Marije; Schlangen, Luc J M; Schellen, Lisje; Frijns, Arjan J H; van Marken Lichtenbelt, Wouter D

2017-06-01

Indoor temperature and light exposure are known to affect body temperature, productivity and alertness of building occupants. However, not much is known about the interaction between light and temperature exposure and the relationship between morning light induced alertness and its effect on body temperature. Light intensity and room temperature during morning office hours were investigated under strictly controlled conditions. In a randomized crossover study, two white light conditions (4000K, either bright 1200lx or dim 5lx) under three different room temperatures (26, 29 and 32°C) were investigated. A lower room temperature increased the core body temperature (CBT) and lowered skin temperature and the distal-proximal temperature gradient (DPG). Moreover, a lower room temperature reduced the subjective sleepiness and reaction time on an auditory psychomotor vigilance task (PVT), irrespective of the light condition. Interestingly, the morning bright light exposure did affect thermophysiological parameters, i.e. it decreased plasma cortisol, CBT and proximal skin temperature and increased the DPG, irrespective of the room temperature. During the bright light session, subjective sleepiness decreased irrespective of the room temperature. However, the change in sleepiness due to the light exposure was not related to these physiological changes. Copyright © 2017 Elsevier Inc. All rights reserved.

Impact of ocean acidification on Arctic phytoplankton blooms and dimethyl sulfide concentration under simulated ice-free and under-ice conditions

NASA Astrophysics Data System (ADS)

Hussherr, Rachel; Levasseur, Maurice; Lizotte, Martine; Tremblay, Jean-Éric; Mol, Jacoba; Thomas, Helmuth; Gosselin, Michel; Starr, Michel; Miller, Lisa A.; Jarniková, Tereza; Schuback, Nina; Mucci, Alfonso

2017-05-01

In an experimental assessment of the potential impact of Arctic Ocean acidification on seasonal phytoplankton blooms and associated dimethyl sulfide (DMS) dynamics, we incubated water from Baffin Bay under conditions representing an acidified Arctic Ocean. Using two light regimes simulating under-ice or subsurface chlorophyll maxima (low light; low PAR and no UVB) and ice-free (high light; high PAR + UVA + UVB) conditions, water collected at 38 m was exposed over 9 days to 6 levels of decreasing pH from 8.1 to 7.2. A phytoplankton bloom dominated by the centric diatoms Chaetoceros spp. reaching up to 7.5 µg chlorophyll a L-1 took place in all experimental bags. Total dimethylsulfoniopropionate (DMSPT) and DMS concentrations reached 155 and 19 nmol L-1, respectively. The sharp increase in DMSPT and DMS concentrations coincided with the exhaustion of NO3- in most microcosms, suggesting that nutrient stress stimulated DMS(P) synthesis by the diatom community. Under both light regimes, chlorophyll a and DMS concentrations decreased linearly with increasing proton concentration at all pH levels tested. Concentrations of DMSPT also decreased but only under high light and over a smaller pH range (from 8.1 to 7.6). In contrast to nano-phytoplankton (2-20 µm), pico-phytoplankton ( ≤ 2 µm) was stimulated by the decreasing pH. We furthermore observed no significant difference between the two light regimes tested in term of chlorophyll a, phytoplankton abundance and taxonomy, and DMSP and DMS net concentrations. These results show that ocean acidification could significantly decrease the algal biomass and inhibit DMS production during the seasonal phytoplankton bloom in the Arctic, with possible consequences for the regional climate.

Pre-slaughter rectal temperature as an indicator of pork meat quality.

PubMed

Vermeulen, L; Van de Perre, V; Permentier, L; De Bie, S; Geers, R

2015-07-01

This study investigates whether rectal temperature of pigs, prior to slaughter, can give an indication of the risk of developing pork with PSE characteristics. A total of 1203 pigs were examined, measuring the rectal temperature just before stunning, of which 794 rectal temperatures were measured immediately after stunning. pH30LT (M. Longissimus thoracis) and temperature of the ham (Temp30Ham) were collected from about 530 carcasses, 30 min after sticking. The results present a significant positive linear correlation between rectal temperature just before and after slaughter, and Temp30Ham. Moreover, pH30LT is negatively correlated with rectal temperature and Temp30Ham. Finally, a linear mixed model for pH30LT was established with the rectal temperature of the pigs just before stunning and the lairage time. This model defines that measuring rectal temperature of pigs just before slaughter allows discovery of pork with PSE traits, taking into account pre-slaughter conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thermosensitive polymer-grafted iron oxide nanoparticles studied by in situ dynamic light backscattering under magnetic hyperthermia

NASA Astrophysics Data System (ADS)

Hemery, Gauvin; Garanger, Elisabeth; Lecommandoux, Sébastien; Wong, Andrew D.; Gillies, Elizabeth R.; Pedrono, Boris; Bayle, Thomas; Jacob, David; Sandre, Olivier

2015-12-01

Thermometry at the nanoscale is an emerging area fostered by intensive research on nanoparticles (NPs) that are capable of converting electromagnetic waves into heat. Recent results suggest that stationary gradients can be maintained between the surface of NPs and the bulk solvent, a phenomenon sometimes referred to as ‘cold hyperthermia’. However, the measurement of such highly localized temperatures is particularly challenging. We describe here a new approach to probing the temperature at the surface of iron oxide NPs and enhancing the understanding of this phenomenon. This approach involves the grafting of thermosensitive polymer chains to the NP surface followed by the measurement of macroscopic properties of the resulting NP suspension and comparison to a calibration curve built up by macroscopic heating. Superparamagnetic iron oxide NPs were prepared by the coprecipitation of ferrous and ferric salts and functionalized with amines, then azides using a sol-gel route followed by a dehydrative coupling reaction. Thermosensitive poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) with an alkyne end-group was synthesized by controlled radical polymerization and was grafted using a copper assisted azide-alkyne cycloaddition reaction. Measurement of the colloidal properties by dynamic light scattering (DLS) indicated that the thermosensitive NPs exhibited changes in their Zeta potential and hydrodynamic diameter as a function of pH and temperature due to the grafted PDMAEMA chains. These changes were accompanied by changes in the relaxivities of the NPs, suggesting application as thermosensitive contrast agents for magnetic resonance imaging (MRI). In addition, a new fibre-based backscattering setup enabled positioning of the DLS remote-head as close as possible to the coil of a magnetic heating inductor to afford in situ probing of the backscattered light intensity, hydrodynamic diameter, and temperature. This approach provides a promising platform for estimating the response of magnetic NPs to application of a radiofrequency magnetic field or for understanding the behaviour of other thermogenic NPs.

Diurnal pH variations of a Glacial Stream: a starting point for Inquiry-driven student and teacher Investigations of a Glacial Ecosystem

NASA Astrophysics Data System (ADS)

O'Brien, W. P.; Galbraith, J.; Fatland, D. R.; Heavner, M.

2009-12-01

Contemporary geoscience research often operates in a mode that generates huge repositories of data available on the internet to the scientific community and the general public. The SEAMONSTER (SM) online data browser of both archival and real-time data is an example of such a dynamic online ecosystem resource associated with the Juneau Icefield. Although newly developed database navigation tools and geobrowsers make it easy for non-experts to access data of interest, it nonetheless can be daunting to K-16 educators to fashion lesson plans that make effective use of these rich resources. In the following scenario, a student and associated teacher, operating outside the traditional didactic lecture/demo mode, explore and try to make sense of a tiny portion of SM data in a spirit of inquiry guided by curiosity, looking for features that catch their attention as they skim through interactive time-series graphs (96 samples/day) of data from Lemon Creek (which drains Lemon Glacier) for stream hydrological variables (temperature, pH, conductivity, dissolved oxygen, turbidity, discharge) and associated meteorological variables (precipitation, humidity, temperature). Amidst all the complex fluctuations that follow no immediately apparent pattern, one regular and continuous feature does stand out: a seemingly sinusoidal diurnal variation in pH of about 0.1 that peaks daily at noon. This high-frequency signal is superimposed on a slower signal characterized by multiple-day trends and larger fluctuations in pH. The resulting composite signal with its easily identifiable patterns is an ideal candidate for investigating Fourier signal decomposition. They hypothesize that photosynthesis could be a contributing factor to the diurnal signal and then design and run an experiment modeling bioactive streamwater with a blended chloroplast-rich slurry of fresh spinach leaves (spinach soup). They put a recording pH meter in the spinach soup and expose it to high and low levels of light; the experiment (based in part on my own actual videotaped spinach-soup study) returns a positive correlation between elevated pH and increased photosynthetic activity in the soup, thereby providing a plausible explanation for micro-scale daily fluctuations in stream pH. They then re-examine the local hydrological and meteorological data, looking for patterns and correlations that might enable them to infer the sources (glacial or watershed) and types of photosynthetic producers/consumers living in Lemon Creek. These results could then be compared with diurnal pH variations also found in a nearby non-glacial stream, Montana Creek. Thus the steady pH heartbeat of a stream in the dynamic ecosystem surrounding a partially-glaciated watershed threads together a diverse set of inquiry-and-data-driven ecological investigations integrating topics from chemistry, biology, physics and informatics.

The laboratory environmental algae pond simulator (LEAPS) photobioreactor: Validation using outdoor pond cultures of Chlorella sorokiniana and Nannochloropsis salina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huesemann, M.; Williams, P.; Edmundson, S.

A bench-scale photobioreactor system, termed Laboratory Environmental Algae Pond Simulator (LEAPS), was designed and constructed to simulate outdoor pond cultivation for a wide range of geographical locations and seasons. The LEAPS consists of six well-mixed glass column photobioreactors sparged with CO2-enriched air to maintain a set-point pH, illuminated from above by a programmable multicolor LED lighting (0 to 2,500 µmol/m2-sec), and submerged in a temperature controlled water-bath (-2 °C to >60 °C). Measured incident light intensities and water temperatures deviated from the respective light and temperature set-points on average only 2.3% and 0.9%, demonstrating accurate simulation of light and temperaturemore » conditions measured in outdoor ponds. In order to determine whether microalgae strains cultured in the LEAPS exhibit the same linear phase biomass productivity as in outdoor ponds, Chlorella sorokiniana and Nannochloropsis salina were cultured in the LEAPS bioreactors using light and temperature scripts measured previously in the respective outdoor pond studies. For Chlorella sorokiniana, the summer season biomass productivity in the LEAPS was 6.6% and 11.3% lower than in the respective outdoor ponds in Rimrock, Arizona, and Delhi, California; however, these differences were not statistically significant. For Nannochloropsis salina, the winter season biomass productivity in the LEAPS was statistically significantly higher (15.2%) during the 27 day experimental period than in the respective outdoor ponds in Tucson, Arizona. However, when considering only the first 14 days, the LEAPS biomass productivity was only 9.2% higher than in the outdoor ponds, a difference shown to be not statistically significant. Potential reasons for the positive or negative divergence in LEAPS performance, relative to outdoor ponds, are discussed. To demonstrate the utility of the LEAPS in predicting productivity, two other strains – Scenedesmus obliquus and Stichococcus minor – were evaluated using the summer season script for Rimrock, Arizona. For both strains, the productivity was around 11.6 g/m2-day at a 25 cm culture depth. In conclusion, the LEAPS is an accurate pond simulator and thus offers a reliable, fast, and cost-effective way for screening microalgae strains and operating conditions for high biomass productivity and co-product yields, using sunlight intensity and water temperature scripts generated by the Biomass Assessment Tool for any geographic location of choice where meteorological data are available.« less

Phototoxicity testing by online irradiation and HPLC.

PubMed

Schröder, Sven; Surmann, J P

2006-11-01

A high-performance liquid chromatography (HPLC) system was developed for the determination of drug photostability and phototoxicity based on an automated column-switching system with aqueous online UV-A irradiation and hyphenated organic separation of the drug and its photoproducts. The photoreactor is built with an poly(ethylene-co-tetrafluoroethylene) (ETFE) reaction coil knitted around a UV-A light source. The chromatographic separation was performed with two special C18 columns, which are also suitable for using with pure water as eluent. Degradation of chlorpromazine (CPZ) by ultraviolet light was investigated at pH 7 and pH 3. Furthermore chlorpromazine was irradiated in the presence of guanosine-5-monophosphate (GMP) in pH 7 buffered solution, leading to a new photoproduct. In the pH 3 irradiation studies of CPZ and GMP, no reaction was detected between the molecules.

Effect of fire-retardant treatment on plywood pH and the relationship of pH to strength properties

Treesearch

S. T. Lebow; J. E. Winandy

1999-01-01

This paper investigates the relationship between wood pH and the strength properties of fire-retardant-treated (FRT) plywood, as it is affected by fire-retardant (FR) formulations, processing variables, and extended high temperature exposure conditions. The objectives of this study were to (1) identify the effect of post-treatment kiln-drying temperature, followed by...

Cell Membrane Fatty Acid Composition of Chryseobacterium frigidisoli PB4T, Isolated from Antarctic Glacier Forefield Soils, in Response to Changing Temperature and pH Conditions

PubMed Central

Bajerski, Felizitas; Wagner, Dirk; Mangelsdorf, Kai

2017-01-01

Microorganisms in Antarctic glacier forefields are directly exposed to the hostile environment of their habitat characterized by extremely low temperatures and changing geochemical conditions. To survive under those stress conditions microorganisms adapt, among others, their cell membrane fatty acid inventory. However, only little is known about the adaptation potential of microorganisms from Antarctic soil environments. In this study, we examined the adaptation of the cell membrane polar lipid fatty acid inventory of Chryseobacterium frigidisoli PB4T in response to changing temperature (0°C to 20°C) and pH (5.5 to 8.5) regimes, because this new strain isolated from an Antarctic glacier forefield showed specific adaptation mechanisms during its detailed physiological characterization. Flavobacteriaceae including Chryseobacterium species occur frequently in extreme habitats such as ice-free oases in Antarctica. C. frigidisoli shows a complex restructuring of membrane derived fatty acids in response to different stress levels. Thus, from 20°C to 10°C a change from less iso-C15:0 to more iso-C17:1ω7 is observed. Below 10°C temperature adaptation is regulated by a constant increase of anteiso-FAs and decrease of iso-FAs. An anteiso- and bis-unsaturated fatty acid, anteiso-heptadeca-9,13-dienoic acid, shows a continuous increase with decreasing cultivation temperatures underlining the particular importance of this fatty acid for temperature adaptation in C. frigidisoli. Concerning adaptation to changing pH conditions, most of the dominant fatty acids reveal constant relative proportions around neutral pH (pH 6–8). Strong variations are mainly observed at the pH extremes (pH 5.5 and 8.5). At high pH short chain saturated iso- and anteiso-FAs increase while longer chain unsaturated iso- and anteiso-FAs decrease. At low pH the opposite trend is observed. The study shows a complex interplay of different membrane components and provides, therefore, deep insights into adaptation strategies of microorganisms from extreme habitats to changing environmental conditions. PMID:28469614

Room-temperature synthesis of Zn(0.80)Cd(0.20)S solid solution with a high visible-light photocatalytic activity for hydrogen evolution.

PubMed

Wang, Dong-Hong; Wang, Lei; Xu, An-Wu

2012-03-21

Visible light photocatalytic H(2) production from water splitting is of great significance for its potential applications in converting solar energy into chemical energy. In this study, a series of Zn(1-x)Cd(x)S solid solutions with a nanoporous structure were successfully synthesized via a facile template-free method at room temperature. The obtained solid solutions were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and N(2) adsorption-desorption analysis. The solid solutions show efficient photocatalytic activity for H(2) evolution from aqueous solutions containing sacrificial reagents S(2-) and SO(3)(2-) under visible-light irradiation without a Pt cocatalyst, and loading of the Pt cocatalyst further improves the visible-light photocatalytic activity. The optimal photocatalyst with x = 0.20 prepared at pH = 7.3 displays the highest activity for H(2) evolution. The bare and 0.25 wt% Pt loaded Zn(0.80)Cd(0.20)S nanoparticles exhibit a high H(2) evolution rate of 193 μmol h(-1) and 458 μmol h(-1) under visible-light irradiation (λ ≥ 420 nm), respectively. In addition, the bare and 0.25 wt% Pt loaded Zn(0.80)Cd(0.20)S catalysts show a high H(2) evolution rate of 252 and 640 μmol h(-1) under simulated solar light irradiation, respectively. Moreover, the Zn(0.80)Cd(0.20)S catalyst displays a high photocatalytic stability for H(2) evolution under long-term light irradiation. The incorporation of Cd in the solid solution leads to the visible light absorption, and the high content of Zn in the solid solution results in a relatively negative conduction band, a modulated band gap and a rather wide valence bandwidth, which are responsible for the excellent photocatalytic performance of H(2) production and for the high photostability. This journal is © The Royal Society of Chemistry 2012

Effects of increased pCO2 and temperature on trace element (Ag, Cd and Zn) bioaccumulation in the eggs of the common cuttlefish, Sepia officinalis

NASA Astrophysics Data System (ADS)

Lacoue-Labarthe, T.; Martin, S.; Oberhänsli, F.; Teyssié, J.-L.; Markich, S.; Jeffree, R.; Bustamante, P.

2009-05-01

Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we are testing the effects of pH and temperature through a crossed (3×2) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the hatchlings weight at the end of development implying egg swelling process and embryo growth disturbances. The lower pH of incubation seawater of eggs, the more the hatchlings accumulated 110m Ag in their tissues. The 109Cd CF decreased with increasing pH and 65Zn CF reached the maximal values pH 7.85, independent of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and the embryo metabolism. To the best of our knowledge, this is one of the first studies on the ocean acidification and ocean warming consequences on the metal uptake in marine organisms, stimulating further interest to evaluate the likely ecotoxicological impact of the global change on the early-life stage of the cuttlefish.

Alternative Antimicrobial Commercial Egg Washing Procedures.

PubMed

Hudson, Lauren K; Harrison, Mark A; Berrang, Mark E; Jones, Deana R

2016-07-01

Commercial table eggs are washed prior to packaging. Standard wash procedures use an alkaline pH and warm water. If a cool water method could be developed that would still provide a microbiologically safe egg, the industry may save energy costs associated with water heating. Four wash procedures were evaluated for Salmonella reduction: pH 11 at 48.9°C (industry standard), pH 11 at ambient temperature (∼20°C), pH 6 at 48.9°C, and pH 6 at ambient temperature. Alkaline washes contained potassium hydroxide-based detergent, while pH 6 washes contained approximately 200 ppm of chlorine and a proprietary chlorine stabilizer (T-128). When eggs were inoculated by immersion in a cell suspension of Salmonella Enteritidis and Salmonella Typhimurium, all treatments resulted in a slight and similar reduction of Salmonella numbers (approximately 0.77 log CFU/ml of shell emulsion reduction). When eggs were inoculated by droplet on the shell surface, Salmonella counts were reduced by approximately 5 log CFU when washed with chlorine plus the chlorine stabilizer at both temperatures and with the alkaline wash at the high temperature. The reductions in Salmonella by these treatments were not significantly (P > 0.05) different from each other but were significantly (P < 0.05) more than the reduction observed for the 20°C alkaline treatment and 20°C control water treatments. Ambient temperature acidic washes reduced Salmonella contamination to the same degree as the standard pH 11 warm water wash and may be a viable option to reduce cost, increase shelf life, and slow pathogen growth in and on shell eggs.

High-Pressure-High-Temperature Processing Reduces Maillard Reaction and Viscosity in Whey Protein-Sugar Solutions.

PubMed

Avila Ruiz, Geraldine; Xi, Bingyan; Minor, Marcel; Sala, Guido; van Boekel, Martinus; Fogliano, Vincenzo; Stieger, Markus

2016-09-28

The aim of the study was to determine the influence of pressure in high-pressure-high-temperature (HPHT) processing on Maillard reactions and protein aggregation of whey protein-sugar solutions. Solutions of whey protein isolate containing either glucose or trehalose at pH 6, 7, and 9 were treated by HPHT processing or conventional high-temperature (HT) treatments. Browning was reduced, and early and advanced Maillard reactions were retarded under HPHT processing at all pH values compared to HT treatment. HPHT induced a larger pH drop than HT treatments, especially at pH 9, which was not associated with Maillard reactions. After HPHT processing at pH 7, protein aggregation and viscosity of whey protein isolate-glucose/trehalose solutions remained unchanged. It was concluded that HPHT processing can potentially improve the quality of protein-sugar-containing foods, for which browning and high viscosities are undesired, such as high-protein beverages.

Mesoporous α-Fe2O3 thin films synthesized via the sol-gel process for light-driven water oxidation.

PubMed

Hamd, Wael; Cobo, Saioa; Fize, Jennifer; Baldinozzi, Gianguido; Schwartz, Wilfrid; Reymermier, Maryse; Pereira, Alexandre; Fontecave, Marc; Artero, Vincent; Laberty-Robert, Christel; Sanchez, Clement

2012-10-14

This work reports a facile and cost-effective method for synthesizing photoactive α-Fe(2)O(3) films as well as their performances when used as photoanodes for water oxidation. Transparent α-Fe(2)O(3) mesoporous films were fabricated by template-directed sol-gel chemistry coupled with the dip-coating approach, followed by annealing at various temperatures from 350 °C to 750 °C in air. α-Fe(2)O(3) films were characterized by X-ray diffraction, XPS, FE-SEM and electrochemical measurements. The photoelectrochemical performance of α-Fe(2)O(3) photoanodes was characterized and optimized through the deposition of Co-based co-catalysts via different methods (impregnation, electro-deposition and photo-electro-deposition). Interestingly, the resulting hematite films heat-treated at relatively low temperature (500 °C), and therefore devoid of any extrinsic dopant, achieve light-driven water oxidation under near-to-neutral (pH = 8) aqueous conditions after decoration with a Co catalyst. The onset potential is 0.75 V vs. the reversible hydrogen electrode (RHE), thus corresponding to 450 mV light-induced underpotential, although modest photocurrent density values (40 μA cm(-2)) are obtained below 1.23 V vs. RHE. These new materials with a very large interfacial area in contact with the electrolyte and allowing for a high loading of water oxidation catalysts open new avenues for the optimization of photo-electrochemical water splitting.

Production of Ultra-Light Normal Incidence Mirrors

NASA Technical Reports Server (NTRS)

Jones, Ruth; Muntele, Iulia; Muntele, Claudiu; Zimmerman, Robert L.; Ila, Daryush; Burdine, Robert V. (Technical Monitor)

2002-01-01

Mirrors fabrication for large aperture telescopes is an important aspect in space exploration programs. One of the cost effective techniques to obtain such mirrors is electroplating of Ni-Co alloys from sulfamate solution. The Center for Irradiation of Materials at Alabama A&M University - Research Institute has been involved in a NASA-MSFC project for producing ultra-light Ni-Co alloy mirrors since the summer of year 2000. The goal of this project is to obtain ultra-light, high strength electroformed large aperture normal incidence replicated mirrors, (weighting less than 5 kg/m2), free of stress, with a good figure and reproducible thickness variation. In order to simplify the control of parameters such as temperature gradient, concentration gradient, distribution of the electric field lines and flow control, the proposed geometry involves a cylindrical main tank contained in another cylindrical tank, which plays the role of a weir. Designs were created to accommodate the new horizontal position of the mandrel and the pipes fitting through the outer tank's lid. The inner tank contains the working electrodes and a series of sensors for monitoring temperature, flow, stress and pH. The outer tank holds the electric heaters, the filters and a part of the piping system. Another two tanks complete the setup and serve for rinsing/preheating and equilibrating the electroplating bath. This paper will describe advantages of the new experimental setup and the parameters achieved in the electroplating bath for the proposed geometry.

Raman spectroscopic approach to monitor the in vitro cyclization of creatine → creatinine

NASA Astrophysics Data System (ADS)

Gangopadhyay, Debraj; Sharma, Poornima; Singh, Sachin Kumar; Singh, Pushkar; Tarcea, Nicolae; Deckert, Volker; Popp, Jürgen; Singh, Ranjan K.

2015-01-01

The creatine → creatinine cyclization, an important metabolic phenomenon has been initiated in vitro at acidic pH and studied through Raman spectroscopic and DFT approach. The equilibrium composition of neutral, zwitterionic and protonated microspecies of creatine has been monitored with time as the reaction proceeds. Time series Raman spectra show clear signature of creatinine formation at pH 3 after ∼240 min at room temperature and reaction is faster at higher temperature. The spectra at pH 1 and pH 5 do not show such signature up to 270 min implying faster reaction rate at pH 3.

Modeling the Effect of pH and Temperature for Cellulases Immobilized on Enzymogel Nanoparticles.

PubMed

Samaratunga, Ashani; Kudina, Olena; Nahar, Nurun; Zakharchenko, Andrey; Minko, Sergiy; Voronov, Andriy; Pryor, Scott W

2015-06-01

Production costs of cellulosic biofuels can be lowered if cellulases are recovered and reused using particulate carriers that can be extracted after biomass hydrolysis. Such enzyme recovery was recently demonstrated using enzymogel nanoparticles with grafted polymer brushes loaded with cellulases. In this work, cellulase (NS50013) and β-glucosidase (Novozyme 188) were immobilized on enzymogels made of poly(acrylic acid) polymer brushes grafted to the surface of silica nanoparticles. Response surface methodology was used to model effects of pH and temperature on hydrolysis and recovery of free and attached enzymes. Hydrolysis yields using both enzymogels and free cellulase and β-glucosidase were highest at the maximum temperature tested, 50 °C. The optimal pH for cellulase enzymogels and free enzyme was 5.0 and 4.4, respectively, while both free β-glucosidase and enzymogels had an optimal pH near 4.4. Highest hydrolysis sugar concentrations with cellulase and β-glucosidase enzymogels were 69 and 53 % of those with free enzymes, respectively. Enzyme recovery using enzymogels decreased with increasing pH, but cellulase recovery remained greater than 88 % throughout the operating range of pH values less than 5.0 and was greater than 95 % at pH values below 4.3. Recovery of β-glucosidase enzymogels was not affected by temperature and had little impact on cellulase recovery.

Effects of salinity, pH and temperature on the re-establishment of bioluminescence and copper or SDS toxicity in the marine dinoflagellate Pyrocystis lunula using bioluminescence as an endpoint

USGS Publications Warehouse

Craig, J.M.; Klerks, P.L.; Heimann, K.; Waits, J.L.

2003-01-01

Pyrocystis lunula is a unicellular, marine, photoautotrophic, bioluminescent dinoflagellate. This organism is used in the Lumitox ?? bioassay with inhibition of bioluminescence re-establishment as the endpoint. Experiments determined if acute changes in pH, salinity, or temperature had an effect on the organisms' ability to re-establish bioluminescence, or on the bioassay's potential to detect sodium dodecyl sulfate (SDS) and copper toxicity. The re-establishment of bioluminescence itself was not very sensitive to changes in pH within the pH 6-10 range, though reducing pH from 8 to levels below 6 decreased this capacity. Increasing the pH had little effect on Cu or SDS toxicity, but decreasing the pH below 7 virtually eliminated the toxicity of either compound in the bioassay. Lowering the salinity from 33 to 27??? or less resulted in a substantial decrease in re-establishment of bioluminescence, while increasing the salinity to 43 or 48 ??? resulted in a small decline. Salinity had little influence on the bioassay's quantification of Cu toxicity, while the data showed a weak negative relationship between SDS toxicity and salinity. Re-establishment of bioluminescence showed a direct dependence on temperature, but only at 10??C did temperature have an obvious effect on the toxicity of Cu in this bioassay. ?? 2003 Elsevier Science Ltd. All rights reserved.

Tagatose production with pH control in a stirred tank reactor containing immobilized L-arabinose rom Thermotoga neapolitana.

PubMed

Lim, Byung-Chul; Kim, Hye-Jung; Oh, Deok-Kun

2008-06-01

Chitopearl beads were used as immobilization supports for D-tagatose production from D-galactose by L-arabinose isomerase from Thermotoga neapolitana because chitopearl beads were more stable than alginate beads at temperatures above 60 degrees C. The pH and temperature for the maximum isomerization of galactose were 7.5 and 90 degrees C, respectively. In thermostability experiments, the half-lives of the immobilized enzyme at 70, 75, 80, 85, and 90 degrees C were 388, 106, 54, 36, and 22 h, respectively. The reaction temperature was determined to be 70 degrees C because the enzyme is highly stable up to 70 degrees C during the reaction. When the reaction time, galactose concentration, and temperature were increased, the pH of a mixture containing enzyme and galactose decreased by the Maillard reaction, resulting in decreased tagatose production. With pH control at 7.5, tagatose production (138 g/L) at 70 degrees C in a stirred tank reactor containing immobilized enzyme and 300 g/L galactose increased two times higher, comparing that without pH control.

Effect of Aging Temperature on Corrosion Behavior of Sintered 17-4 PH Stainless Steel in Dilute Sulfuric Acid Solution

NASA Astrophysics Data System (ADS)

Szewczyk-Nykiel, Aneta; Kazior, Jan

2017-07-01

The general corrosion behavior of sintered 17-4 PH stainless steel processed under different processing conditions in dilute sulfuric acid solution at 25 °C was studied by open-circuit potential measurement and potentiodynamic polarization technique. The corrosion resistance was evaluated based on electrochemical parameters, such as polarization resistance, corrosion potential, corrosion current density as well as corrosion rate. The results showed that the precipitation-hardening treatment could significantly improve the corrosion resistance of the sintered 17-4 PH stainless steel in studied environment. As far as the influence of aging temperature on corrosion behavior of the sintered 17-4 PH stainless steel is concerned, polarization resistance and corrosion rate are reduced with increasing aging temperature from 480 up to 500 °C regardless of the temperature of solution treatment. It can be concluded that the highest corrosion resistance in 0.5 M H2SO4 solution exhibits 17-4 PH after solution treatment at 1040 °C followed by aging at 480 °C.

Thermodynamic and transport properties of frozen and reacting pH2-oH2 mixtures

NASA Technical Reports Server (NTRS)

Carter, H. G.; Bullock, R. E.

1972-01-01

Application of experimental state data and spectroscopic term values shows that the thermodynamic and transport properties of reacting pH2-oH2 mixtures are considerably different than those of chemically frozen pH2 at temperatures below 300 R. Calculated H-S data also show that radiation-induced pH2-oH2 equilibration at constant enthalpy produces a temperature drop of at least 28 R, corresponding to an ideal shaft work loss of 15% or more for a turbine operating downstream from the point of conversion. Aside from differences in thermodynamic and transport properties, frozen pH2-oH2 mixtures may differ from pure pH2 on a purely hydrodynamical basis.

40 CFR 411.25 - Standards of performance for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (maximum for any 1 day) Metric units (kg/kkg of dust leached) TSS 0.4. Temperature (heat) Not to exceed 3 °C rise above inlet temperature. pH Within the range 6.0 to 9.0. English units (lb/1,000 lb of dust leached) TSS 0.4. Temperature (heat) Not to exceed 3 °C rise above inlet temperature. pH Within the range...

40 CFR 411.25 - Standards of performance for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (maximum for any 1 day) Metric units (kg/kkg of dust leached) TSS 0.4. Temperature (heat) Not to exceed 3 °C rise above inlet temperature. pH Within the range 6.0 to 9.0. English units (lb/1,000 lb of dust leached) TSS 0.4. Temperature (heat) Not to exceed 3 °C rise above inlet temperature. pH Within the range...

X-Ray Excited Luminescence Chemical Imaging of Bacterial Growth on Surfaces Implanted in Tissue.

PubMed

Wang, Fenglin; Raval, Yash; Tzeng, Tzuen-Rong J; Anker, Jeffrey N

2015-04-22

A pH sensor film is developed that can be coated on an implant surface and imaged using a combination of X-ray excitation and visible spectroscopy to monitor bacterial infection and treatment of implanted medical devices (IMDs) through tissue. X-ray scintillators in the pH sensor film generate light when an X-ray beam irradiates them. This light first passes through a layer containing pH indicator that alters the spectrum according to pH, then passes through and out of the tissue where it is detected by a spectrometer. A reference region on the film is used to account for spectral distortion from wavelength-dependent absorption and scattering in the tissue. pH images are acquired by moving the sample relative to the X-ray beam and collecting a spectrum at each location, with a spatial resolution limited by the X-ray beam width. Using this X-ray excited luminescence chemical imaging (XELCI) to map pH through ex vivo porcine tissue, a pH drop is detected during normal bacterial growth on the sensor surface, and a restoration of the pH to the bulk value during antibiotic treatment over the course of hours with milli-meter resolution. Overall, XELCI provides a novel approach to noninvasively image surface pH for studying implant infections and treatments. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optoelectronic Instrument Monitors pH in a Culture Medium

NASA Technical Reports Server (NTRS)

Anderson, Melody M.; Pellis, Neal; Jeevarajan, Anthony S.; Taylor, Thomas D.

2004-01-01

An optoelectronic instrument monitors the pH of an aqueous cell-culture medium in a perfused rotating-wall-vessel bioreactor. The instrument is designed to satisfy the following requirements: It should be able to measure the pH of the medium continuously with an accuracy of 0.1 in the range from 6.5 to 7.5. It should be noninvasive. Any material in contact with the culture medium should be sterilizable as well as nontoxic to the cells to be grown in the medium. The biofilm that inevitably grows on any surface in contact with the medium should not affect the accuracy of the pH measurement. It should be possible to obtain accurate measurements after only one calibration performed prior to a bioreactor cell run. The instrument should be small and lightweight. The instrument includes a quartz cuvette through which the culture medium flows as it is circulated through the bioreactor. The cuvette is sandwiched between light source on one side and a photodetector on the other side. The light source comprises a red and a green light-emitting diode (LED) that are repeatedly flashed in alternation with a cycle time of 5 s. The responses of the photodiode to the green and red LEDs are processed electronically to obtain a quantity proportional to the ratio between the amounts of green and red light transmitted through the medium.

Dynamic light-scattering study of gelatin and aggregation of gastric mucin

NASA Astrophysics Data System (ADS)

Bansil, Rama; Cao, Xingxiang; Bhaskar, K. Ramakrishnan; LaMont, Jeffrey T.

1997-05-01

Dynamic light scattering studies show that concentration and pH play important roles in determining pig gastric mucin's (PGM) ability to aggregate and gel. At low concentrations, PGM macromolecules exist in solution predominantly in the form of monomers. At high concentrations, PGM macromolecules aggregate to form supra-macromolecular clusters. When the pH of the high concentration PGM solution is changed from 7.0 to 2.0, the system undergoes a sol-gel transition: from a solution of polydisperse aggregates to a gel. This pH and concentration dependent sol-gel transition of PGM solution may provide a mechanism for the mammalian stomach to protect itself against being digested by the gastric juice.

Characteristics of cold-induced dark, firm, dry broiler chicken breast meat.

PubMed

Dadgar, S; Lee, E S; Crowe, T G; Classen, H L; Shand, P J

2012-01-01

1. A study was designed to characterise dark, firm, dry (DFD) breast meat resulting from cold exposure of broilers and compare its properties with normal breast meat from cold-stressed and control birds. 2. A total of 140 broilers were selected from 5- and 6-week-old birds exposed to cold temperatures ranging from -18 to -4°C, or a control temperature of +20°C for 3 h in an environmental chamber. Half of these birds were slaughtered immediately following the cold exposure and the other half were given 2 h of lairage. 3. Breast meat samples were categorised based on ultimate pH (pH(u)) and colour L* (lightness) values into normal (5·7 ≤ pH(u)≤ 6·1; 46 ≤ L* ≤ 53) breast meat from control (control-normal) or cold-stressed (cold-normal) birds, and DFD (pH(u) > 6·1; L* < 46) breast meat, which only occurred in cold-stressed birds (cold-DFD). 4. Residual glycogen was not different between cold-DFD and control-normal breast meat. Lactate concentration was lower in cold-DFD compared with control-normal breast meat. Lactate concentration almost tripled for all the samples by 30 h post-mortem, which resulted in a drop in pH of normal meat, but did not have any effect on pH of DFD breast meat. Glycolytic potential at both 5 min and 30 h post-mortem was lower in DFD breast meat compared with the normal breast meat from both cold-stressed and control birds. 5. Cold-DFD breast meat was significantly darker, with higher pH(u), lower cook loss, higher water-binding capacity and processing cook yield than cold-normal and control-normal breast meat, which were not different from each other.

Residual stresses in injection molded shape memory polymer parts

NASA Astrophysics Data System (ADS)

Katmer, Sukran; Esen, Huseyin; Karatas, Cetin

2016-03-01

Shape memory polymers (SMPs) are materials which have shape memory effect (SME). SME is a property which has the ability to change shape when induced by a stimulator such as temperature, moisture, pH, electric current, magnetic field, light, etc. A process, known as programming, is applied to SMP parts in order to alter them from their permanent shape to their temporary shape. In this study we investigated effects of injection molding and programming processes on residual stresses in molded thermoplastic polyurethane shape memory polymer, experimentally. The residual stresses were measured by layer removal method. The study shows that injection molding and programming process conditions have significantly influence on residual stresses in molded shape memory polyurethane parts.

Low temperature synthesis and characterization of carbonated hydroxyapatite nanocrystals

NASA Astrophysics Data System (ADS)

Anwar, Aneela; Asghar, Muhammad Nadeem; Kanwal, Qudsia; Kazmi, Mohsin; Sadiqa, Ayesha

2016-08-01

Carbonate substituted hydroxyapatite (CHA) nanorods were synthesized via coprecipitation method from aqueous solution of calcium nitrate tetrahydrate and diammonium hydrogen phosphate (with urea as carbonate ion source) in the presence of ammonium hydroxide solution at 70 °C at the conditions of pH 11. The obtained powders were physically characterized using transmission electron microscopy (TEM), X-ray powder diffraction analysis (XRD), and FTIR and Raman spectroscopy. The particle size was evaluated by Dynamic light scattering (DLS). The chemical structural analysis of as prepared sample was performed using X-ray photoelectron spectroscopy (XPS). After ageing for 12 h, and heat treatment at 1000 °C for 1 h, the product was obtained as highly crystalline nanorods of CHA.

External-Stimuli-Assisted Control over Assemblies of Plasmonic Metals.

PubMed

Watanabe, Kanako; Kuroda, Kotaro; Nagao, Daisuke

2018-05-15

Assembly of plasmonic nanoparticles (NPs) in suspensions is a promising approach for the control of optical and sensing properties that depend on the assembled states of plasmonic NPs. This review focuses on the controlling methods to assemble the NP via external stimuli such as pH, temperature, light, magnetic field, and electric field. External stimuli are introduced as powerful tools to assemble the NPs because of various operational factors, such as the intensity, application time, and frequency, which can be employed. In addition to a summary of recent studies on the controlling methods, a future study on the reversible control over assembled states of the plasmonic NPs via external stimuli is proposed.

A concise review on smart polymers for controlled drug release.

PubMed

Aghabegi Moghanjoughi, Arezou; Khoshnevis, Dorna; Zarrabi, Ali

2016-06-01

Design and synthesis of efficient drug delivery systems are of critical importance in health care management. Innovations in materials chemistry especially in polymer field allows introduction of advanced drug delivery systems since polymers could provide controlled release of drugs in predetermined doses over long periods, cyclic and tunable dosages. To this end, researchers have taken advantages of smart polymers since they can undergo large reversible, chemical, or physical fluctuations as responses to small changes in environmental conditions, for instance, in pH, temperature, light, and phase transition. The present review aims to highlight various kinds of smart polymers, which are used in controlled drug delivery systems as well as mechanisms of action and their applications.

A review of responsive MRI contrast agents: 2005–2014

PubMed Central

Hingorani, Dina V.; Bernstein, Adam S.; Pagel, Mark D.

2014-01-01

This review focuses on MRI contrast agents that are responsive to a change in a physiological biomarker. The response mechanisms are dependent on six physicochemical characteristics, including the accessibility of water to the agent, tumbling time, proton exchange rate, electron spin state, MR frequency, or superparamagnetism of the agent. These characteristics can be affected by changes in concentrations or activities of enzymes, proteins, nucleic acids, metabolites, or metal ions, or changes in redox state, pH, temperature, or light. A total of 117 examples are presented, including examples that employ nuclei other than 1H, which attests to the creativity of multidisciplinary research efforts to develop responsive MRI contrast agents. PMID:25355685

The Influence of Arginine on the Response of Enamel Matrix Derivative (EMD) Proteins to Thermal Stress: Towards Improving the Stability of EMD-Based Products

PubMed Central

Bolisetty, Sreenath; Marascio, Matteo; Gemperli Graf, Anja; Garamszegi, Laszlo; Mezzenga, Raffaele; Fischer, Peter; Månson, Jan-Anders

2015-01-01

In a current procedure for periodontal tissue regeneration, enamel matrix derivative (EMD), which is the active component, is mixed with a propylene glycol alginate (PGA) gel carrier and applied directly to the periodontal defect. Exposure of EMD to physiological conditions then causes it to precipitate. However, environmental changes during manufacture and storage may result in modifications to the conformation of the EMD proteins, and eventually premature phase separation of the gel and a loss in therapeutic effectiveness. The present work relates to efforts to improve the stability of EMD-based formulations such as Emdogain™ through the incorporation of arginine, a well-known protein stabilizer, but one that to our knowledge has not so far been considered for this purpose. Representative EMD-buffer solutions with and without arginine were analyzed by 3D-dynamic light scattering, UV-Vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy at different acidic pH and temperatures, T, in order to simulate the effect of pH variations and thermal stress during manufacture and storage. The results provided evidence that arginine may indeed stabilize EMD against irreversible aggregation with respect to variations in pH and T under these conditions. Moreover, stopped-flow transmittance measurements indicated arginine addition not to suppress precipitation of EMD from either the buffers or the PGA gel carrier when the pH was raised to 7, a fundamental requirement for dental applications. PMID:26670810

Heteroprotein Complex Formation of Bovine Lactoferrin and Pea Protein Isolate: A Multiscale Structural Analysis.

PubMed

Adal, Eda; Sadeghpour, Amin; Connell, Simon; Rappolt, Michael; Ibanoglu, Esra; Sarkar, Anwesha

2017-02-13

Associative electrostatic interactions between two oppositely charged globular proteins, lactoferrin (LF) and pea protein isolate (PPI), the latter being a mixture of vicilin, legumin, and convicilin, was studied with a specific PPI/LF molar ratio at room temperature. Structural aspects of the electrostatic complexes probed at different length scales were investigated as a function of pH by means of different complementary techniques, namely, with dynamic light scattering, small-angle X-ray scattering (SAXS), turbidity measurements, and atomic force microscopy (AFM). Irrespective of the applied techniques, the results consistently displayed that complexation between LF and PPI did occur. In an optimum narrow range of pH 5.0-5.8, a viscous liquid phase of complex coacervate was obtained upon mild centrifugation of the turbid LF-PPI mixture with a maximum R h , turbidity and the ζ-potential being close to zero observed at pH 5.4. In particular, the SAXS data demonstrated that the coacervates were densely assembled with a roughly spherical size distribution exhibiting a maximum extension of ∼80 nm at pH 5.4. Equally, AFM image analysis showed size distributions containing most frequent cluster sizes around 40-80 nm with spherical to elliptical shapes (axis aspect ratio ≤ 2) as well as less frequent elongated to chainlike structures. The most frequently observed compact complexes, we identify as mainly leading to LF-PPI coacervation, whereas for the less frequent chain-like aggregates, we hypothesize that additionally PPI-PPI facilitated complexes exist.

The Influence of Arginine on the Response of Enamel Matrix Derivative (EMD) Proteins to Thermal Stress: Towards Improving the Stability of EMD-Based Products.

PubMed

Apicella, Alessandra; Heunemann, Peggy; Bolisetty, Sreenath; Marascio, Matteo; Gemperli Graf, Anja; Garamszegi, Laszlo; Mezzenga, Raffaele; Fischer, Peter; Plummer, Christopher J; Månson, Jan-Anders

2015-01-01

In a current procedure for periodontal tissue regeneration, enamel matrix derivative (EMD), which is the active component, is mixed with a propylene glycol alginate (PGA) gel carrier and applied directly to the periodontal defect. Exposure of EMD to physiological conditions then causes it to precipitate. However, environmental changes during manufacture and storage may result in modifications to the conformation of the EMD proteins, and eventually premature phase separation of the gel and a loss in therapeutic effectiveness. The present work relates to efforts to improve the stability of EMD-based formulations such as Emdogain™ through the incorporation of arginine, a well-known protein stabilizer, but one that to our knowledge has not so far been considered for this purpose. Representative EMD-buffer solutions with and without arginine were analyzed by 3D-dynamic light scattering, UV-Vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy at different acidic pH and temperatures, T, in order to simulate the effect of pH variations and thermal stress during manufacture and storage. The results provided evidence that arginine may indeed stabilize EMD against irreversible aggregation with respect to variations in pH and T under these conditions. Moreover, stopped-flow transmittance measurements indicated arginine addition not to suppress precipitation of EMD from either the buffers or the PGA gel carrier when the pH was raised to 7, a fundamental requirement for dental applications.

Physical Instability of a Therapeutic Fc Fusion Protein: Domain Contributions to Conformational and Colloidal Stability†

PubMed Central

Fast, Jonas L; Cordes, Amanda A; Carpenter, John F; Randolph, Theodore W

2009-01-01

Protein therapeutics made up of artificially combined proteins or protein domains, so called fusion proteins, are a novel and growing class of biopharmaceuticals. We have studied abatacept (Orencia®), a fusion protein that is constructed of a modified IgG Fc domain and the soluble part of the T-cell receptor CTLA-4. In accelerated degradation studies conducted at at 40 °C, a pH shift from 7.5 to 6.0 yields significantly faster aggregation kinetics, as measured by size-exclusion chromatography. To understand how the fusion domains and their interactions contribute to this result, we considered aggregation in light of the modified Lumry-Eyring reaction pathway. Protein conformational stabilities against chaotropes and temperature were measured. The structural consequences of these perturbations were observed by a variety of experimental techniques, including differential scanning calorimetry, circular dichroism, and intrinsic fluorescence. Abatacept’s colloidal stability was studied by measuring zeta potentials and osmotic second virial coefficients, as well as by modeling electrostatic potentials on the protein’s surface. The domains of abatacept exhibit different conformational stabilities that are highly pH dependent, whereas abatacept was weakly colloidally unstable at pH 6 or pH 7.5. These results are ascribed to conformational instability of the CTLA-4 and CH2 domains, which unfold to form a molten globule-like structure that is aggregation-prone. We suggest the instability against aggregation is determined by the least stable domains. PMID:19899812

Development of a vision-based pH reading system

NASA Astrophysics Data System (ADS)

Hur, Min Goo; Kong, Young Bae; Lee, Eun Je; Park, Jeong Hoon; Yang, Seung Dae; Moon, Ha Jung; Lee, Dong Hoon

2015-10-01

pH paper is generally used for pH interpretation in the QC (quality control) process of radiopharmaceuticals. pH paper is easy to handle and useful for small samples such as radio-isotopes and radioisotope (RI)-labeled compounds for positron emission tomography (PET). However, pHpaper-based detecting methods may have some errors due limitations of eye sight and inaccurate readings. In this paper, we report a new device for pH reading and related software. The proposed pH reading system is developed with a vision algorithm based on the RGB library. The pH reading system is divided into two parts. First is the reading device that consists of a light source, a CCD camera and a data acquisition (DAQ) board. To improve the accuracy of the sensitivity, we utilize the three primary colors of the LED (light emission diode) in the reading device. The use of three colors is better than the use of a single color for a white LED because of wavelength. The other is a graph user interface (GUI) program for a vision interface and report generation. The GUI program inserts the color codes of the pH paper into the database; then, the CCD camera captures the pH paper and compares its color with the RGB database image in the reading mode. The software captures and reports information on the samples, such as pH results, capture images, and library images, and saves them as excel files.

Suitable Water Flow and Water Temperature Difference of Blast Furnace

NASA Astrophysics Data System (ADS)

Zuo, Hai-bin; Li, Qian; Zhang, Jian-liang; Shen, Meng; Tie, Jin-yan; Jiao, Ke-xin

This paper designs three factors such as temperature, pH, conductivity and three levels of orthogonal test. Temperature is a significant factor. However PH and conductivity are not significant through poor analysis. Further research is conducted on the temperature. Temperature stability is 50°C. Suitable water velocity is 2.3m/s, which is calculated based on the largest part of the heat flux intensity and the corresponding water temperature should be controlled with 1.5°C. Meanwhile, water velocity increased has little effect on the heat transfer capabilities.

Design of aquaponics water monitoring system using Arduino microcontroller

NASA Astrophysics Data System (ADS)

Murad, S. A. Z.; Harun, A.; Mohyar, S. N.; Sapawi, R.; Ten, S. Y.

2017-09-01

This paper describes the design of aquaponics water monitoring system using Arduino microcontroller. Arduino Development Environment (IDE) software is used to develop a program for the microcontroller to communicate with multiple sensors and other hardware. The circuit of pH sensor, temperature sensor, water sensor, servo, liquid crystal displays (LCD), peristaltic pump, solar and Global System for Mobile communication (GSM) are constructed and connected to the system. The system powered by a rechargeable battery using solar energy. When the results of pH, temperature and water sensor are out of range, a notification message will be sent to a mobile phone through GSM. If the pH of water is out of range, peristaltic pump is automatic on to maintain back the pH value of water. The water sensor is fixed in the siphon outlet water flow to detect water flow from grow bed to the fish tank. In addition, servo is used to auto feeding the fish for every 12 hours. Meanwhile, the LCD is indicated the pH, temperature, siphon outlet water flow and remaining time for the next feeding cycle. The pH and temperature of water are set in the ranges of 6 to 7 and 25 °C to 30 °C, respectively.

Allergenicity of Peanut Proteins is Retained Following Enzymatic Hydrolysis

USDA-ARS?s Scientific Manuscript database

Rationale: Hydrolysis of peanut proteins by food-grade enzymes may reduce allergenicity and could lead to safer forms of immunotherapy. Methods: Light roasted peanut flour extracts were digested with pepsin (37°C, pH 2), Alcalase (60°C pH 8), or Flavourzyme (50°C, pH 7) up to 1 hr, or sequentially w...

A pH sensing system using fluorescence-based fibre optical sensor capable of small volume sample measurement

NASA Astrophysics Data System (ADS)

Deng, Shijie; McAuliffe, Michael A. P.; Salaj-Kosla, Urszula; Wolfe, Raymond; Lewis, Liam; Huyet, Guillaume

2017-02-01

In this work, a low cost optical pH sensing system that allows for small volume sample measurements was developed. The system operates without the requirement of laboratory instruments (e.g. laser source, spectrometer and CCD camera), this lowers the cost and enhances the portability. In the system, an optical arrangement employing a dichroic filter was used which allows the excitation and emission light to be transmitted using a single fibre thus improving the collection efficiency of the fluorescence signal and also the ability of inserting measurement. The pH sensor in the system uses bromocresol purple as the indicator which is immobilised by sol-gel technology through a dip-coating process. The sensor material was coated on the tip of a 1 mm diameter optical fibre which makes it possible for inserting into very small volume samples to measure the pH. In the system, a LED with a peak emission wavelength of 465 nm is used as the light source and a silicon photo-detector is used to detect the uorescence signal. Optical filters are applied after the LED and in front of the photo-detector to separate the excitation and emission light. The fluorescence signal collected is transferred to a PC through a DAQ and processed by a Labview-based graphic-user-interface (GUI). Experimental results show that the system is capable of sensing pH values from 5.3 to 8.7 with a linear response of R2=0.969. Results also show that the response times for a pH changes from 5.3 to 8.7 is approximately 150 s and for a 0.5 pH changes is approximately 50 s.

Optimizing isothiocyanate formation during enzymatic glucosinolate breakdown by adjusting pH value, temperature and dilution in Brassica vegetables and Arabidopsis thaliana

NASA Astrophysics Data System (ADS)

Hanschen, Franziska S.; Klopsch, Rebecca; Oliviero, Teresa; Schreiner, Monika; Verkerk, Ruud; Dekker, Matthijs

2017-01-01

Consumption of glucosinolate-rich Brassicales vegetables is associated with a decreased risk of cancer with enzymatic hydrolysis of glucosinolates playing a key role. However, formation of health-promoting isothiocyanates is inhibited by the epithiospecifier protein in favour of nitriles and epithionitriles. Domestic processing conditions, such as changes in pH value, temperature or dilution, might also affect isothiocyanate formation. Therefore, the influences of these three factors were evaluated in accessions of Brassica rapa, Brassica oleracea, and Arabidopsis thaliana. Mathematical modelling was performed to determine optimal isothiocyanate formation conditions and to obtain knowledge on the kinetics of the reactions. At 22 °C and endogenous plant pH, nearly all investigated plants formed nitriles and epithionitriles instead of health-promoting isothiocyanates. Response surface models, however, clearly demonstrated that upon change in pH to domestic acidic (pH 4) or basic pH values (pH 8), isothiocyanate formation considerably increases. While temperature also affects this process, the pH value has the greatest impact. Further, a kinetic model showed that isothiocyanate formation strongly increases due to dilution. Finally, the results show that isothiocyanate intake can be strongly increased by optimizing the conditions of preparation of Brassicales vegetables.

Sudden collapse of vacuoles in Saintpaulia sp. palisade cells induced by a rapid temperature decrease.

PubMed

Kadohama, Noriaki; Goh, Tatsuaki; Ohnishi, Miwa; Fukaki, Hidehiro; Mimura, Tetsuro; Suzuki, Yoshihiro

2013-01-01

It is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv. 'Iceberg') and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury.

Sudden Collapse of Vacuoles in Saintpaulia sp. Palisade Cells Induced by a Rapid Temperature Decrease

PubMed Central

Kadohama, Noriaki; Goh, Tatsuaki; Ohnishi, Miwa; Fukaki, Hidehiro; Mimura, Tetsuro; Suzuki, Yoshihiro

2013-01-01

It is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv. ‘Iceberg’) and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury. PMID:23451194

One-pot ultrasonic-assisted method for preparation of Ag/AgCl sensitized ZnO nanostructures as visible-light-driven photocatalysts

NASA Astrophysics Data System (ADS)

Naghizadeh-Alamdari, Sara; Habibi-Yangjeh, Aziz; Pirhashemi, Mahsa

2015-02-01

Ultrasonic-assisted method was applied for preparation of Ag/AgCl sensitized ZnO nanostructures by one-pot procedure in water without using any post preparation treatments. The resultant nanocomposites were characterized by XRD, EDX, SEM, DRS, XPS, BET, and PL techniques. In the nanocomposites, ZnO and AgCl have wurtzite hexagonal and cubic crystalline phases, respectively and their surface morphologies remarkably change with increasing mole fraction of silver chloride. The EDX and XPS techniques show that the prepared samples are extremely pure. Ability of the nanocomposites for absorption of visible-light irradiation enhanced with increasing AgCl content. Photocatalytic examination of the nanocomposites was carried out using aqueous solution of methylene blue under visible-light irradiation. The degradation rate constant on the nancomposite rapidly increases with mole fraction of silver chloride up to 0.237. Enhancing activity of the nanocomposite was attributed to its ability for absorbing visible light and separation of electron-hole pairs. Furthermore, influence of ultrasonic irradiation time, calcination temperature, catalyst weight, pH of solution, and scavengers of reactive species on the degradation activity was investigated and the results were discussed. Finally, the photocatalyst has good activity after five successive cycles.

Effect of pH and temperature on the uptake of cadmium by Lemna minor L

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chawla, G.; Singh, J.; Viswanathan, P.N.

1991-07-01

Many aquatic macrophytes have the capacity to take up toxic heavy metals from polluted water and accumulate them. Cut leaves and intact plants have been suggested for clearing polluted water bodies of heavy metals. However, uptake of metal ion from water is dependent on concentration, pH, temperature, presence of other substances and functional and morphological status of the biotic species. In an attempt to understand any correlation between metal bioconcentration, pH and temperature, the optimal conditions for the removal of cadmium ions by duckweed, Lemna minor (L.) were studied.

Exploring the process-structure-function relationship of horseradish peroxidase through investigation of pH- and heat induced conformational changes

NASA Astrophysics Data System (ADS)

Stănciuc, Nicoleta; Aprodu, Iuliana; Ioniță, Elena; Bahrim, Gabriela; Râpeanu, Gabriela

2015-08-01

Given the importance of peroxidase as an indicator for the preservation of vegetables by heat treatment, the present study is focused on enzyme behavior under different pH and temperature conditions, in terms of process-structure-function relationships. Thus, the process-structure-function relationship of peroxidase was investigated by combining fluorescence spectroscopy, in silico prediction methods and inactivation kinetic studies. The fluorescence spectra indicated that at optimum pH value, the Trp117 residue is not located in the hydrophobic core of the protein. Significant blue- and red-shifts were obtained at different pH values, whereas the heat-treatment did not cause significant changes in Trp and Tyr environment. The ANS and quenching experiments demonstrated a more flexible conformation at lower pH and respectively at higher temperature. On the other hand molecular dynamics simulations at different temperatures highlighted that the secondary structure appeared better preserved against temperature, whereas the tertiary structure around the heme was more affected. Temperature dependent changes in the hydrogen bonding and ion paring involving amino acids from the heme-binding region (His170 and Asp247) might trigger miss-coordination of the heme iron atom by His170 residue and further enzyme activity loss.

Ruminal temperature may aid in the detection of subacute ruminal acidosis.

PubMed

AlZahal, O; Kebreab, E; France, J; Froetschel, M; McBride, B W

2008-01-01

The objective of this study was to investigate the relationship between ruminal pH and ruminal temperature and to develop a predictive equation that can aid in the diagnosis of subacute ruminal acidosis (SARA). Six rumen-fistulated lactating Holstein dairy cows (639 +/- 51 kg body weight) were used in the study. Cows were randomly allocated to 1 of 2 dietary treatments: control (% of dry matter, 40% corn silage, 27% mixed haylage, 7% alfalfa hay, 18% protein supplement, 4% ground corn, and 4% wheat bran) or SARA total mixed ration (% of dry matter, 31% corn silage, 20% mixed haylage, 5% alfalfa hay, 15% protein supplement, 19% ground wheat, and 10% ground barley) and were fed daily at 0700 and 1300 h. The experiment consisted of 1 wk of adaptation followed by 1 wk of treatment. Ruminal pH and ruminal temperature were simultaneously and continuously recorded every minute for 4 d per week using the same indwelling electrode. Subacute-acidotic cows spent more time (min/d) below ruminal pH 5.6 and a greater time above 39.2 degrees C than control cows. Ruminal pH nadir had a negative relationship with its corresponding ruminal temperature (R2 = 0.77). Therefore, ruminal temperature may have potential to predict ruminal pH and thus aid in the diagnosis of SARA.

Stability of urea in solution and pharmaceutical preparations.

PubMed

Panyachariwat, Nattakan; Steckel, Hartwig

2014-01-01

The stability of urea in solution and pharmaceutical preparations was analyzed as a function of temperature (25°-60°C), pH (3.11-9.67), and initial urea concentration (2.5%-20%). This study was undertaken to (i) obtain more extensive, quantitative information relative to the degradation of urea in both aqueous and non-aqueous solutions and in pharmaceutical preparations, and (ii) test the effects of initial urea concentration, pH, buffer, and temperature values on urea degradation. The stability analysis shows that urea is more stable at the pH range of 4-8 and the stability of urea decreases by increase in temperature for all pH values. Within the experimental range of temperature and initial urea concentration values, the lowest urea degradation was found with lactate buffer pH 6.0. The urea decomposition rate in solution and pharmaceutical preparations shows the dependence of the initial urea concentrations. At higher initial urea concentrations, the rate of degradation is a decreasing function with time. This suggests that the reverse reaction is a factor in the degradation of concentrated urea solution. For non-aqueous solvents, isopropanol showed the best effort in retarding the decomposition of urea. Since the losses in urea is directly influenced by its stability at a given temperature and pH, the stability analysis of urea by the proposed model can be used to prevent the loss and optimize the operating condition for urea-containing pharmaceutical preparations.

Light energy conservation processes in Halobacterium halobium cells

NASA Technical Reports Server (NTRS)

Bogomolni, R. A.

1977-01-01

Proton pumping driven by light or by respiration generates an electrochemical potential difference across the membrane in Halobacterium halobium. The pH changes induced by light or by respiration in cell suspensions are complicated by proton flows associated with the functioning of the cellular energy transducers. A proton-per-ATP ratio of about 3 is calculated from simultaneous measurements of phosphorylation and the proton inflow. This value is compatible with the chemiosmotic coupling hypothesis. The time course of the light-induced changes in membrane potential indicates that light-driven pumping increases a dark pre-existing potential of about 130 mV only by a small amount (20 to 30 mV). The complex kinetic features of the membrane potential changes do not closely follow those of the pH changes, which suggests that flows of ions other than protons are involved. A qualitative model consistent with the available data is presented.

Photonic crystal light emitting diode based on Er and Si nanoclusters co-doped slot waveguide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lo Savio, R.; Galli, M.; Liscidini, M.

We report on the design, fabrication, and electro-optical characterization of a light emitting device operating at 1.54 μm, whose active layer consists of silicon oxide containing Er-doped Si nanoclusters. A photonic crystal (PhC) is fabricated on the top-electrode to enhance the light extraction in the vertical direction, and thus the external efficiency of the device. This occurs if a photonic mode of the PhC slab is resonant with the Er emission energy, as confirmed by theoretical calculations and experimental analyses. We measure an increase of the extraction efficiency by a factor of 3 with a high directionality of light emission inmore » a narrow vertical cone. External quantum efficiency and power efficiency are among the highest reported for this kind of material. These results are important for the realization of CMOS-compatible efficient light emitters at telecom wavelengths.« less

Novel robust cellulose-based foam with pH and light dual-response for oil recovery

NASA Astrophysics Data System (ADS)

Wang, Qian; Meng, Guihua; Wu, Jianning; Wang, Yixi; Liu, Zhiyong; Guo, Xuhong

2018-05-01

We fabricated pH and light dual-responsive adsorption materials which could induce the transition of surface wettability between hydrophobicity and hydrophilicity by using ATRP. The structure and morphology of adsorption materials were confirmed by ATR-FTIR, XPS, TGA and SEM. It showed that the modified cellulose (CE)-based foam was hydrophobic, which can adsorb a range of oils and organic solvents in water under pH = 7.0 or visible light irradiation (λ > 500 nm). Meanwhile, the wettability of robust CE-based foam can convert hydrophobicity into hydrophilicity and underwater oleophobicity under pH = 3.0 or UV irradiation (λ = 365 nm), giving rise to release oils and organic solvents. Most important of all, the adsorption and desorption processes of the modified CE-based foam could be switched by external stimuli. Furthermore, the modified CE-based foam was not damaged and still retained original performance after reversible cycle repeated for many times with variation of surface wettability. In short, it indicates that CE-based foam materials with switchable surface wettability are new responsive absorbent materials and have owned potential application in the treatment of oil recovery.

Identification of pH-sensing Sites in the Light Harvesting Complex Stress-related 3 Protein Essential for Triggering Non-photochemical Quenching in Chlamydomonas reinhardtii

DOE PAGES

Ballottari, Matteo; Truong, Thuy B.; De Re, Eleonora; ...

2016-01-27

Light harvesting complex stress-related 3 (LHCSR3) is the protein essential for photoprotective excess energy dissipation (non-photochemical quenching, NPQ) in the model green alga Chlamydomonas reinhardtii. Activation of NPQ requires low pH in the thylakoid lumen, which is induced in excess light conditions and sensed by lumen-exposed acidic residues. In this work we have used site-specific mutagenesis in vivo and in vitro for identification of the residues in LHCSR3 that are responsible for sensing lumen pH. Lumen-exposed protonatable residues, aspartate and glutamate, were mutated to asparagine and glutamine, respectively. By expression in a mutant lacking all LHCSR isoforms, residues Asp 117,more » Glu 221, and Glu 224 were shown to be essential for LHCSR3-dependent NPQ induction in C. reinhardtii. Analysis of recombinant proteins carrying the same mutations refolded in vitro with pigments showed that the capacity of responding to low pH by decreasing the fluorescence lifetime, present in the wild-type protein, was lost. Consistent with a role in pH sensing, the mutations led to a substantial reduction in binding the NPQ inhibitor dicyclohexylcarbodiimide.« less

Identification of pH-sensing Sites in the Light Harvesting Complex Stress-related 3 Protein Essential for Triggering Non-photochemical Quenching in Chlamydomonas reinhardtii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ballottari, Matteo; Truong, Thuy B.; De Re, Eleonora

Light harvesting complex stress-related 3 (LHCSR3) is the protein essential for photoprotective excess energy dissipation (non-photochemical quenching, NPQ) in the model green alga Chlamydomonas reinhardtii. Activation of NPQ requires low pH in the thylakoid lumen, which is induced in excess light conditions and sensed by lumen-exposed acidic residues. In this work we have used site-specific mutagenesis in vivo and in vitro for identification of the residues in LHCSR3 that are responsible for sensing lumen pH. Lumen-exposed protonatable residues, aspartate and glutamate, were mutated to asparagine and glutamine, respectively. By expression in a mutant lacking all LHCSR isoforms, residues Asp 117,more » Glu 221, and Glu 224 were shown to be essential for LHCSR3-dependent NPQ induction in C. reinhardtii. Analysis of recombinant proteins carrying the same mutations refolded in vitro with pigments showed that the capacity of responding to low pH by decreasing the fluorescence lifetime, present in the wild-type protein, was lost. Consistent with a role in pH sensing, the mutations led to a substantial reduction in binding the NPQ inhibitor dicyclohexylcarbodiimide.« less

Evaluation of fatty acid profile and biodiesel properties of microalga Scenedesmus abundans under the influence of phosphorus, pH and light intensities.

PubMed

Mandotra, S K; Kumar, Pankaj; Suseela, M R; Nayaka, S; Ramteke, P W

2016-02-01

The present study dealt with biomass, lipid concentration, fatty acid profile and biodiesel properties of microalga Scenedesmus abundans under different phosphate concentrations, pH and light intensities, one at a time. Among different phosphate concentrations, higher biomass (770.10±11.0mg/L) and lipid concentration (176.87±4.6mg/L) were at the concentration of 60mg/L. Light intensity at 6000lux yielded higher biomass and lipid concentration of 742.0±9.7 and 243.15±9.1mg/L, respectively. The biomass (769.0±12.3mg/L) and lipid (179.47±5.5mg/L) concentration were highest at pH 8 and pH 6, respectively. All the culture treatments showed marked effect on the fatty acid profile and biodiesel properties of the extracted oil. FAME derived biodiesel properties were compared with European biodiesel standards (EN 14214), Indian biodiesel standards (IS 15607) and American biodiesel standards (ASTM D 6751-08) to assess the suitability of algal oil as biodiesel feedstock. Copyright © 2015. Published by Elsevier Ltd.

Identification of pH-sensing Sites in the Light Harvesting Complex Stress-related 3 Protein Essential for Triggering Non-photochemical Quenching in Chlamydomonas reinhardtii.

PubMed

Ballottari, Matteo; Truong, Thuy B; De Re, Eleonora; Erickson, Erika; Stella, Giulio R; Fleming, Graham R; Bassi, Roberto; Niyogi, Krishna K

2016-04-01

Light harvesting complex stress-related 3 (LHCSR3) is the protein essential for photoprotective excess energy dissipation (non-photochemical quenching, NPQ) in the model green algaChlamydomonas reinhardtii Activation of NPQ requires low pH in the thylakoid lumen, which is induced in excess light conditions and sensed by lumen-exposed acidic residues. In this work we have used site-specific mutagenesisin vivoandin vitrofor identification of the residues in LHCSR3 that are responsible for sensing lumen pH. Lumen-exposed protonatable residues, aspartate and glutamate, were mutated to asparagine and glutamine, respectively. By expression in a mutant lacking all LHCSR isoforms, residues Asp(117), Glu(221), and Glu(224)were shown to be essential for LHCSR3-dependent NPQ induction inC. reinhardtii Analysis of recombinant proteins carrying the same mutations refoldedin vitrowith pigments showed that the capacity of responding to low pH by decreasing the fluorescence lifetime, present in the wild-type protein, was lost. Consistent with a role in pH sensing, the mutations led to a substantial reduction in binding the NPQ inhibitor dicyclohexylcarbodiimide. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Quantitative color measurement of pH indicator paper using trichromatic LEDs and TCS230 color sensor

NASA Astrophysics Data System (ADS)

Ghorude, T. N.; Chaudhari, A. L.; Shaligram, A. D.

2008-11-01

Quantitative analysis of pH indicator paper color is needed in the various fields. An indigenously developed Tristimulus colorimeter is used in this work for pH Indicator paper color measurement. The colorimeter uses Trichromatic RGB LEDs and a programmable color light to frequency converter (TCS230), combining configurable silicon photodiodes and a current to frequency converter on a single monolithic CMOS integrated circuit. The output is a square wave (50% duty cycle) with frequency directly proportional to light intensity. Digital input and digital output allow directly to a microcontroller. The light to frequency converter reads an 8*8 array of photodiodes. Sixteen photodiodes have red filters, 16 photodiodes have green filters, 16 photodiodes have blue filters, and 16 photodiodes are clear with no filters. All 16 photodiodes of the same colors are connected in parallel and type of photodiode the device uses during operation is pin selectable. Solutions having different standard pH were prepared and indicator paper was dipped in solution, it shows change in color. Using the developed RGB colorimeter chromaticity coordinates were measured and compared with the chromaticity coordinates measured using Ocean Optics HR-4000 high resolution spectrophotometer.

Novel robust cellulose-based foam with pH and light dual-response for oil recovery

NASA Astrophysics Data System (ADS)

Wang, Qian; Meng, Guihua; Wu, Jianning; Wang, Yixi; Liu, Zhiyong; Guo, Xuhong

2018-06-01

We fabricated pH and light dual-responsive adsorption materials which could induce the transition of surface wettability between hydrophobicity and hydrophilicity by using ATRP. The structure and morphology of adsorption materials were confirmed by ATR-FTIR, XPS, TGA and SEM. It showed that the modified cellulose (CE)-based foam was hydrophobic, which can adsorb a range of oils and organic solvents in water under pH = 7.0 or visible light irradiation ( λ > 500 nm). Meanwhile, the wettability of robust CE-based foam can convert hydrophobicity into hydrophilicity and underwater oleophobicity under pH = 3.0 or UV irradiation ( λ = 365 nm), giving rise to release oils and organic solvents. Most important of all, the adsorption and desorption processes of the modified CE-based foam could be switched by external stimuli. Furthermore, the modified CE-based foam was not damaged and still retained original performance after reversible cycle repeated for many times with variation of surface wettability. In short, it indicates that CE-based foam materials with switchable surface wettability are new responsive absorbent materials and have owned potential application in the treatment of oil recovery.

Smartphone-based simultaneous pH and nitrite colorimetric determination for paper microfluidic devices.

PubMed

Lopez-Ruiz, Nuria; Curto, Vincenzo F; Erenas, Miguel M; Benito-Lopez, Fernando; Diamond, Dermot; Palma, Alberto J; Capitan-Vallvey, Luis F

2014-10-07

In this work, an Android application for measurement of nitrite concentration and pH determination in combination with a low-cost paper-based microfluidic device is presented. The application uses seven sensing areas, containing the corresponding immobilized reagents, to produce selective color changes when a sample solution is placed in the sampling area. Under controlled conditions of light, using the flash of the smartphone as a light source, the image captured with the built-in camera is processed using a customized algorithm for multidetection of the colored sensing areas. The developed image-processing allows reducing the influence of the light source and the positioning of the microfluidic device in the picture. Then, the H (hue) and S (saturation) coordinates of the HSV color space are extracted and related to pH and nitrite concentration, respectively. A complete characterization of the sensing elements has been carried out as well as a full description of the image analysis for detection. The results show good use of a mobile phone as an analytical instrument. For the pH, the resolution obtained is 0.04 units of pH, 0.09 of accuracy, and a mean squared error of 0.167. With regard to nitrite, 0.51% at 4.0 mg L(-1) of resolution and 0.52 mg L(-1) as the limit of detection was achieved.

The Influence of Virus Infection on the Extracellular pH of the Host Cell Detected on Cell Membrane.

PubMed

Liu, Hengjun; Maruyama, Hisataka; Masuda, Taisuke; Honda, Ayae; Arai, Fumihito

2016-01-01

Influenza virus infection can result in changes in the cellular ion levels at 2-3 h post-infection. More H(+) is produced by glycolysis, and the viral M2 proton channel also plays a role in the capture and release of H(+) during both viral entry and egress. Then the cells might regulate the intracellular pH by increasing the export of H(+) from the intracellular compartment. Increased H(+) export could lead indirectly to increased extracellular acidity. To detect changes in extracellular pH of both virus-infected and uninfected cells, pH sensors were synthesized using polystyrene beads (ϕ1 μm) containing Rhodamine B and Fluorescein isothiocyanate (FITC). The fluorescence intensity of FITC can respond to both pH and temperature. So Rhodamine B was also introduced in the sensor for temperature compensation. Then the pH can be measured after temperature compensation. The sensor was adhered to cell membrane for extracellular pH measurement. The results showed that the multiplication of influenza virus in host cell decreased extracellular pH of the host cell by 0.5-0.6 in 4 h after the virus bound to the cell membrane, compared to that in uninfected cells. Immunostaining revealed the presence of viral PB1 protein in the nucleus of virus-bound cells that exhibited extracellular pH changes, but no PB1 protein are detected in virus-unbound cells where the extracellular pH remained constant.

Tunable SPR-based remote actuation of bimetallic core-shell nanoparticles-coated stimuli responsive polymer for switchable chemo-photothermal synergistic cancer therapy.

PubMed

Amoli-Diva, Mitra; Sadighi-Bonabi, Rasoul; Pourghazi, Kamyar

2018-06-14

New dual light/temperature-responsive nanocarriers were synthesized using bimetallic plasmonic Au-Ag and Ag-Au nanoparticles (NPs) as cores of vehicles which subsequently functionalized with a UCST-based poly acrylamide-co-acrylonitrile using reversible addition-fragmentation chain transfer for spatiotemporally controlled chemo-photothermal synergistic cancer therapy. The bimetallic cores were assigned to sense wavelengths close to the localized SPR of monometallic NP shell to produce heat which not only can increase the surrounding temperature over the UCST of polymer to open the its valves and promote drug diffusion, but also can kill cancerous cells through photothermal effects with increasing in environment temperature nearly 18 °C after about 5 min radiation. The bimetallic NPs were shown good reusability even after five heating/cooling cycles and the efficiency of both photothermal/chemotherapic procedures can be modulated by manipulating carrier's concentration and radiation time. In addition, the cytotoxicity of drug-free nanocarriers on normal L929 fibroblast and letrozole-loaded nanocarriers on MDAMB 231 breast-cancer cell lines were investigated in the absence/presence of laser radiation. Finally, the prepared nanocomposites were exhibited switchable on/off drug release in two buffered solutions (pH 5.5 and 7.4) with light actuation. The results revealed that the prepared nanocarriers can be served as efficient delivery platforms for remote-control chemo-photothermal synergistic cancer therapy. Copyright © 2018. Published by Elsevier Inc.