A novel optical probe for pH sensing in gastro-esophageal apparatus

NASA Astrophysics Data System (ADS)

Baldini, F.; Ghini, G.; Giannetti, A.; Senesi, F.; Trono, C.

2011-03-01

Monitoring gastric pH for long periods, usually 24 h, may be essential in analyzing the physiological pattern of acidity, in obtaining information on changes in activity during peptic ulcer disease, and in assessing the effect of antisecretory drugs. Gastro-esophageal reflux, which causes a pH decrease in the esophagus content from pH 7 even down to pH 2, can determine esophagitis with possible strictures and Barrett's esophagus. One of the difficulties of the optical measurement of pH in the gastro-esophageal apparatus lies in the required extended working range from 1 to 8 pH units. The present paper deals with a novel optical pH sensor, using methyl red as optical pH indicator. Contrary to all acidbase indicators characterized by working ranges limited to 2-3 pH units, methyl red, after its covalent immobilization on controlled pore glass (CPG), is characterized by a wide working range which fits with the clinical requirements. The novel probe design here described is suitable for gastro-esophageal applications and allows the optimization of the performances of the CPG with the immobilised indicator. This leads to a very simple configuration characterized by a very fast response time.

A Simple Method for Decreasing the Liquid Junction Potential in a Flow-through-Type Differential pH Sensor Probe Consisting of pH-FETs by Exerting Spatiotemporal Control of the Liquid Junction

PubMed Central

Yamada, Akira; Mohri, Satoshi; Nakamura, Michihiro; Naruse, Keiji

2015-01-01

The liquid junction potential (LJP), the phenomenon that occurs when two electrolyte solutions of different composition come into contact, prevents accurate measurements in potentiometry. The effect of the LJP is usually remarkable in measurements of diluted solutions with low buffering capacities or low ion concentrations. Our group has constructed a simple method to eliminate the LJP by exerting spatiotemporal control of a liquid junction (LJ) formed between two solutions, a sample solution and a baseline solution (BLS), in a flow-through-type differential pH sensor probe. The method was contrived based on microfluidics. The sensor probe is a differential measurement system composed of two ion-sensitive field-effect transistors (ISFETs) and one Ag/AgCl electrode. With our new method, the border region of the sample solution and BLS is vibrated in order to mix solutions and suppress the overshoot after the sample solution is suctioned into the sensor probe. Compared to the conventional method without vibration, our method shortened the settling time from over two min to 15 s and reduced the measurement error by 86% to within 0.060 pH. This new method will be useful for improving the response characteristics and decreasing the measurement error of many apparatuses that use LJs. PMID:25835300

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.

Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release.

PubMed

Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

2015-01-01

Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery.

Engineering polyelectrolyte multilayer structure at the nanometer length scale by tuning polymer solution conformation.

NASA Astrophysics Data System (ADS)

Boddohi, Soheil; Killingsworth, Christopher; Kipper, Matt

2008-03-01

Chitosan (a weak polycation) and heparin (a strong polyanion) are used to make polyelectrolyte multilayers (PEM). PEM thickness and composition are determined as a function of solution pH (4.6 to 5.8) and ionic strength (0.1 to 0.5 M). Over this range, increasing pH increases the PEM thickness; however, the sensitivity to changes in pH is a strong function of ionic strength. The PEM thickness data are correlated to the polymer conformation in solution. Polyelectrolyte conformation in solution is characterized by gel permeation chromatography (GPC). The highest sensitivity of PEM structure to pH is obtained at intermediate ionic strength. Different interactions govern the conformation and adsorption phenomena at low and high ionic strength, leading to reduced sensitivity to solution pH at extreme ionic strengths. The correspondence between PEM thickness and polymer solution conformation offers opportunities to tune polymer thin film structure at the nanometer length scale by controlling simple, reproducible processing conditions.

Preparing "Chameleon Balls" from Natural Plants: Simple Handmade pH Indicator and Teaching Material for Chemical Equilibrium

NASA Astrophysics Data System (ADS)

Kanda, Naoki; Asano, Takayuki; Itoh, Toshiyuki; Onoda, Makoto

1995-12-01

Anthocyanins are found in the flowers and fruits of natural plants. Since their color depends on pH, they are sometines used as a pH indicator. Since these sequences are reversible, they are also useful in demonstrating chemical equilibrium in the repetitive color changes of anthocyanins from flowers by controlling pH conditions. We prepared the polysaccharide beads conatining water extracts of red cabbage as calcium alginate. The beads showed a clear red color under acidic conditions, turned blue at neutral pH of 7, and orange-yellow at pH of 13. This color change could be demonstrated over and over. Because the color changes of these polysaccharide beads depended darmatically on pH, junior high students in science classes called them "chameleon balls" when we demonstrated this reaction for them. In this paper we describe how polysaccharide beads, which are made from calcium alginate with natural pigments, served as a teaching tool for the chemical equilibrium of anthocyanins under different pH conditions. Preparation of the chameleon ball is very easy. The most important thing is that making the chameleon ball is great fun. The ball should therefore be viewed not only as a handmade pH indicator but also an interesting teaching tool of the chemical equilibrium reaction.

On the observation of the need for an unusually high concentration of cysteine and homocysteine to induce aggregation of polymer-stabilized gold nano particles

NASA Astrophysics Data System (ADS)

Radhakumary, C.; Sreenivasan, K.

2013-02-01

This study reports the interaction of chitosan-stabilized gold nanoparticles (CH-AuNPs) with cysteine (Cys) and homocysteine (Hcys) in aqueous media at pH 1.4. Since the polymer precipitates at higher pH, and the amino acids Cys and HCys are soluble at acidic pH, we kept the pH around 1.4 for stabilizing the particles. Zeta potential of CH-AuNPs was found to be positive and it is reasonable to assume that +ve Cys or Hcys at pH 1.4 will experience repulsive force. However, TEM images and absorption spectra indicated formation of aggregates including rod-like assembly. An interesting observation was the need for unusually high concentration of analytes (Cys and Hcys) to induce the assembly of CH-AuNPs. We also found time bound variation of the optical properties probably indicating the interaction is kinetically controlled and only a fraction of the analyte molecules having sufficient energy can bind onto the particles. We observed that at elevated temperature, the reaction was faster with a lower concentration of Cys or Hcys. These observations were supported by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory which describes the interparticle interaction and the colloidal stability in solution. Only molecules possessing enough energy to cross this force barrier can cause the aggregation. We also noted a time lag between Cys and Hcys to influence optical properties reflecting the possibility of using this simple approach to discriminate these two clinically relevant molecules. Our observation shows that simple sensing as well as generation of novel nanostructures could be manipulated by a judicious choice of conditions such as stabilizing agents, pH, etc.

Preparation of novel cotton fabric composites with pH controlled switchable wettability for efficient water-in-oil and oil-in-water emulsions separation

NASA Astrophysics Data System (ADS)

Wang, Qian; Wu, Jianning; Meng, Guihua; Wang, Yixi; Liu, Zhiyong; Guo, Xuhong

2018-06-01

The wetting materials with the ability of controllable oil/water separation have drawn more and more public attention. In this article, the novel cotton fabric (CF) with pH controlled wettability transition was designed by a simple, environmentally friendly coating copolymer/SiO2 nanoparticles, poly(heptadecafluorodecyl methacrylate- co-3-trimethoxysilylpropyl methacrylate- co-2-vinilpiridine) (PHDFDMA- co-PTMSPMA- co-P2VP). Furthermore, the structures and morphologies of coated CF were confirmed by Fourier transform infrared spectroscopy (FTIR), NMR, GPC, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The coated CF exhibits switchable wettability between superhydrophobicity and superhydrophilicity via adjusting pH value. When the coated CF is placed in the neutral aqueous (pH = 7.0), it is superhydrophobic in the air and superoleophilic. It allows oil to go through but blocking water. However, in acidic aqueous environment (pH = 3.0), it turns superhydrophilic and underwater superoleophobic, which allows water to penetrate but blocking oil. Therefore, the coated CF could be applied to separate oil/water mixtures, ternary oil/water/water mixtures continuously and different surfactant stabilized emulsions (oil-in-water, water-in-oil) and displays the superior separation capacity for oil-water mixtures with a high efficiency of 99.8%. Moreover, the cycling tests demonstrate that the coated CF possesses excellent recyclability and durability. Such an eminent, controllable water/oil permeation feature makes coated CF could be selected as an ideal candidate for oil/water separation.

Prescription Proportion of Pomegranate Extract Gallic Acid Gel by Orthogonal Design

NASA Astrophysics Data System (ADS)

Fan, Gaofu; Liu, Xiushu; Tang, Jie; Gong, Jumei; Fu, Entao; Cai, Yuhua; Xu, Zhenguo

2018-05-01

The aim of the present work was to optimize the formulation of pomegranate extract gallic acid gel by orthogonal design. Using orthogonal design, propylene glycol, carbomer-940 and gel pH level as influencing factors, the evaluation key index was external apearance malleability, uniformity, and eccentric for gel, and the optimum formula was selected. The present findings suggest that 10% propylene glycol, 1.5% Carbopol-940, and gel pH in the range of 4.5∼5.5, and the indexes of the optimal. The inclusion complexes showed that after the orthogonal design, the preparation process was simple, stable and controllable quality, with production feasibility.

Study of the Characteristics of Pulmonary Trunk in Pulmonary Hypertension Secondary to Left Heart Disease Using Pressure-Velocity Loops (PU-Loops).

PubMed

Hanya, Shizuo; Yoshii, Kengo; Sugawara, Motoaki

2017-09-25

Objectives : Although pulmonary hypertension (PH) caused by left heart disease (PH-LHD) is more common in PH, little is known about its properties of pulmonary artery (PA) in PH-LHD. The purpose of this study was to measure pulmonary regional pulse wave velocity (PWV) and to quantify the magnitude of reflected waves in patients with PH-LHD by the analysis of the pressure-velocity loops (PU-loop). Methods : High-fidelity PA pressure (Pm) and PA velocity (Vm) were measured in 11 subjects with PH-LHD (mean Pm>25 mmHg), 1 subject with atrial septal defect (ASD) without PH and 12 control subjects, using multisensor catheters. PWV was calculated as the slope of the initial part of the PU-loop in early systole. The similarity in the shapes of the pressure and flow velocity waveforms over one PU-loop was quantified as the magnitude of reflected wave by calculating the standard error of the estimate (Sy/x) from linear regression analysis between Pm and corresponding Vm. PWV and Sy/x during a Valsalva maneuver (VM) were also assessed in nine control subjects. Results : The contour of PU-loop was so characteristic between control and PH-LHD. Max. PWV (349 cm/s) was recorded in PH-LHD and min. PWV (111 cm/s) was recorded in ASD. VM increased Pm (12 [7-15] mmHg vs. 50 [18-110] mmHg; p=0.009) and PWV (200 [148-238] cm/s vs. 260 [192-306] cm/s; p=0.009) significantly without significant increase of Sy/x (19.6 [12.7-28.9]% vs. 28.2 [19.3-40.7]%; p=0.079). Although Sy/x was significantly higher in PH-LHD than in control and ASD (31.0 [14.3-36.3]% vs. 17.5 [8.4-28.9]%; p=0.009, ASD: 18.2%) , no significant difference was found in PWV between PH-LHD and control (269 [159-349] cm/s vs. 203 [154-289] cm/s; p=0.089). Conclusions : 1) The magnitude of wave reflection was elevated in PH-LHD significantly as compared with control and ASD. 2) Despite the significant increase in PA-PWV caused by abrupt elevation in Pm during VM in control, chronic elevation in Pm did not increase PA-PWV in PH-LHD significantly. It was hypothesized that the PA constituted a self-regulating system for maintaining the arterial stiffness stable against the chronic elevation in Pm in PH-LHD by a remodeling of increasing proximal pulmonary arterial crosssectional area gradually, which was compatible with the Moens-Korteweg equation. The PU-loop could provide a new simple and conventional method for assessing the pulmonary arterial properties, clinically. (This is a translation of J Jpn Coll Angiol 2016; 56: 45-53.).

Study of the Characteristics of Pulmonary Trunk in Pulmonary Hypertension Secondary to Left Heart Disease Using Pressure–Velocity Loops (PU-Loops)

PubMed Central

Hanya, Shizuo; Yoshii, Kengo; Sugawara, Motoaki

2017-01-01

Objectives: Although pulmonary hypertension (PH) caused by left heart disease (PH-LHD) is more common in PH, little is known about its properties of pulmonary artery (PA) in PH-LHD. The purpose of this study was to measure pulmonary regional pulse wave velocity (PWV) and to quantify the magnitude of reflected waves in patients with PH-LHD by the analysis of the pressure–velocity loops (PU-loop). Methods: High-fidelity PA pressure (Pm) and PA velocity (Vm) were measured in 11 subjects with PH-LHD (mean Pm>25 mmHg), 1 subject with atrial septal defect (ASD) without PH and 12 control subjects, using multisensor catheters. PWV was calculated as the slope of the initial part of the PU-loop in early systole. The similarity in the shapes of the pressure and flow velocity waveforms over one PU-loop was quantified as the magnitude of reflected wave by calculating the standard error of the estimate (Sy/x) from linear regression analysis between Pm and corresponding Vm. PWV and Sy/x during a Valsalva maneuver (VM) were also assessed in nine control subjects. Results: The contour of PU-loop was so characteristic between control and PH-LHD. Max. PWV (349 cm/s) was recorded in PH-LHD and min. PWV (111 cm/s) was recorded in ASD. VM increased Pm (12 [7–15] mmHg vs. 50 [18–110] mmHg; p=0.009) and PWV (200 [148–238] cm/s vs. 260 [192–306] cm/s; p=0.009) significantly without significant increase of Sy/x (19.6 [12.7–28.9]% vs. 28.2 [19.3–40.7]%; p=0.079). Although Sy/x was significantly higher in PH-LHD than in control and ASD (31.0 [14.3–36.3]% vs. 17.5 [8.4–28.9]%; p=0.009, ASD: 18.2%) , no significant difference was found in PWV between PH-LHD and control (269 [159–349] cm/s vs. 203 [154–289] cm/s; p=0.089). Conclusions: 1) The magnitude of wave reflection was elevated in PH-LHD significantly as compared with control and ASD. 2) Despite the significant increase in PA-PWV caused by abrupt elevation in Pm during VM in control, chronic elevation in Pm did not increase PA-PWV in PH-LHD significantly. It was hypothesized that the PA constituted a self-regulating system for maintaining the arterial stiffness stable against the chronic elevation in Pm in PH-LHD by a remodeling of increasing proximal pulmonary arterial crosssectional area gradually, which was compatible with the Moens–Korteweg equation. The PU-loop could provide a new simple and conventional method for assessing the pulmonary arterial properties, clinically. (This is a translation of J Jpn Coll Angiol 2016; 56: 45–53.) PMID:29147168

Influence of pH on Drug Absorption from the Gastrointestinal Tract: A Simple Chemical Model

NASA Astrophysics Data System (ADS)

Hickman, Raymond J. S.; Neill, Jane

1997-07-01

A simple model of the gastrointestinal tract is obtained by placing ethyl acetate in contact with water at pH 2 and pH 8 in separate test tubes. The ethyl acetate corresponds to the lipid material lining the tract while the water corresponds to the aqueous contents of the stomach (pH 2) and intestine (pH 8). The compounds aspirin, paracetamol and 3-aminophenol are used as exemplars of acidic, neutral and basic drugs respectively to illustrate the influence which pH has on the distribution of each class of drug between the aqueous and organic phases of the model. The relative concentration of drug in the ethyl acetate is judged by applying microlitre-sized samples of ethyl acetate to a layer of fluorescent silica which, after evaporation of the ethyl acetate, is viewed under an ultraviolet lamp. Each of the three drugs, if present in the ethyl acetate, becomes visible as a dark spot on the silica layer. The observations made in the model system correspond well to the patterns of drug absorption from the gastrointestinal tract described in pharmacology texts and these observations are convincingly explained in terms of simple acid-base chemistry.

pH dependent green synthesis of gold nanoparticles by completely C6-carboxylated curdlan under high temperature and various pH conditions.

PubMed

Qiu, Wen-Yi; Wang, Kai; Wang, Yao-Yao; Ding, Zhi-Chao; Wu, Li-Xia; Cai, Wu-Dan; Yan, Jing-Kun

2018-01-01

A C6-carboxylated curdlan (C6-Cc) obtained from 4-acetamido-TEMPO-mediated oxidation of curdlan was used both as a reducing and stabilizing agent for green synthesis of pH-responsive AuNPs, which was carried out by controlling the pH of the C6-Cc solution at a high temperature (100°C). C6-Cc presented a semi-flexible random coil chain in the aqueous medium at pH 5.5 and became more expanded and rigid in alkaline conditions (pH 7.1-12.0), though the primary chemical structure of C6-Cc was virtually unchanged with the pH variation. The AuNPs prepared with C6-Cc at various pHs were characterized by various instrumental measurements. The shapes and sizes of AuNPs were found to be strongly dependent on the pH of the C6-Cc solution. The C6-Cc-decorated AuNPs exhibited a more well-dispersed spherical morphology with smaller particle sizes under alkaline conditions (pH 7.1-12.0). Through this study, a facile, simple, and green method has been demonstrated for preparation of stimuli-sensitive AuNPs using biocompatible polyanionic polysaccharides. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile synthesis of biocompatible gold nanoparticles with organosilicone-coated surface properties

NASA Astrophysics Data System (ADS)

Xia, Lijin; Yi, Sijia; Lenaghan, Scott C.; Zhang, Mingjun

2012-07-01

In this study, a simple method for one-step synthesis of gold nanoparticles has been developed using an organosilicone surfactant, Silwet L-77, as both a reducing and capping agent. Synthesis of gold nanoparticles using this method is rapid and can be conducted conveniently at ambient temperature. Further refinement of the method, through the addition of sodium hydroxide and/or silver nitrate, allowed fine control over the size of spherical nanoparticles produced. Coated on the surface with organosilicone, the as-prepared gold nanoparticles were biocompatible and stable over the pH range from 5 to 12, and have been proven effective at transportation into MC3T3 osteoblast cells. The proposed method is simple, fast, and can produce size-controlled gold nanoparticles with unique surface properties for biomedical applications.

Use of the VS-sense swab in diagnosing vulvovaginitis.

PubMed

Sobel, Jack D; Nyirjesy, Paul; Kessary, Hadar; Ferris, Daron G

2009-09-01

Although pH assessment of vaginal secretions is beneficial for diagnosing vaginitis, it is not commonly done. The purpose of this study was to determine the performance characteristics of the VS-Sense (pH test) swab (Common Sense, Ltd., Caesarea, Israel) in augmenting the diagnosis of vaginitis. We prospectively studied 193 women with acute vulvovaginal symptoms and 74 asymptomatic controls at three medical centers. The VS-Sense swab was administered intravaginally, and results were interpreted by a nurse. These results were compared with final clinical and laboratory diagnoses. In women with an elevated pH caused by bacterial vaginosis (BV), trichomonas, and other types of vaginitis, the VS-Sense test sensitivity and specificity were 82.3% (102 of 124) (95% CI 74.4%-88.5%) and 94.2% (129 of 137) (95% CI 88.8%-97.4%), respectively. There was an 86.2% (95% CI 81.3%-90.1%) overall agreement between pH paper and VS-Sense swab results. The VS-Sense test offers an alternative approach to measuring vaginal pH with nitrazine paper. Use of this simple, more rapid test may facilitate the diagnosis of vulvovaginitis.

The formation of stable pH gradients with weak monovalent buffers for isoelectric focusing in free solution

NASA Technical Reports Server (NTRS)

Mosher, Richard A.; Thormann, Wolfgang; Graham, Aly; Bier, Milan

1985-01-01

Two methods which utilize simple buffers for the generation of stable pH gradients (useful for preparative isoelectric focusing) are compared and contrasted. The first employs preformed gradients comprised of two simple buffers in density-stabilized free solution. The second method utilizes neutral membranes to isolate electrolyte reservoirs of constant composition from the separation column. It is shown by computer simulation that steady-state gradients can be formed at any pH range with any number of components in such a system.

Evaluation of pH and calcium ion diffusion from calcium hydroxide pastes and MTA.

PubMed

Sáez, María Del M; López, Gabriela L; Atlas, Diana; de la Casa, María L

2017-04-01

The aim of this ex vivo study was to evaluate changes in pH and calcium ion diffusion through root dentin from calcium hydroxide (Ca (OH) 2 ) and mineral trioxide aggregate (MTA) pastes at 7, 30 and 60 days; and the relationship between pH and ion diffusion. Thirty-two human premolars were used. Crowns were sectioned and root canals instrumented and filled in with the following preparations: 1) Ca(OH) 2 + distilled water (n=7); 2) Ca(OH) 2 + 0.1% chlorhexidine gluconate (n=7); 3) MTA + distilled water (n=7); 4) MTA + 0.1% chlorhexidine gluconate (CHX) (n=7); 5) distilled water (n=2) (control); 6) 0.1% chlorhexidine gluconate (n=2) (control). The apex and coronary opening were sealed with IRM. Roots were placed in Eppendorf tubes with 1 ml distilled water at 37°C and 100% humidity. At baseline, 7, 30 and 60 days, pH was measured with pH meter, and calcium ion content in the solution was analyzed by atomic absorption spectrophotometry. The data were statistically analyzed using ANOVA, simple linear regression analysis and Pearson's correlation test. The highest pH values were achieved with calcium hydroxide pastes at 60 days (p ≤ 0.05). Calcium ions were released in all groups. The calcium hydroxide paste with distilled water at 60 days had the highest calcium ion value (p ≤ 0.01). There was a positive correlation between calcium and pH values. Sociedad Argentina de Investigación Odontológica.

Virtual Protein Purification: A Simple Exercise to Introduce pH as A Parameter That Effects Ion Exchange Chromatography

ERIC Educational Resources Information Center

Clark, Daniel D.; Edwards, Daniel J.

2018-01-01

This article describes a simple exercise using a free, easy-to-use, established online program. The exercise helps to reinforce protein purification concepts and introduces undergraduates to pH as a parameter that affects anion-exchange chromatography. The exercise was tested with biochemistry majors at California State University-Chico. Given the…

Preparing "Chameleon Balls" from Natural Plants: Simple Handmade pH Indicator and Teaching Material for Chemical Education

NASA Astrophysics Data System (ADS)

1996-05-01

Some of the structures in Figure 1 from "Preparing "Chameleon Balls" from Natural Plants: Simple Handmade pH Indicator and Teaching Material for Chemical Education"[Kanda, N.; Asano, T.; Itoh, T.; Onoda, M. J. Chem. Educ. 1995, 72, 1131] were incorrect due to a staff error. The correct figure appears below.

A Simple Experiment for Visualizing Diffusion

ERIC Educational Resources Information Center

Helseth, L. E.

2011-01-01

We propose a simple and fascinating experiment for studying diffusion in gels using a pH-sensitive dye. By doping agar with methyl red, we obtain a gel which rapidly reacts to changes in pH by changing its absorption spectrum. The pH gradients can be followed using a digital camera, and we demonstrate here that the pH-sensitive colour changes can…

Perendoscopic gastric pH determination. Simple method for increasing accuracy in diagnosing chronic atrophic gastritis.

PubMed

Farinati, F; Cardin, F; Di Mario, F; Sava, G A; Piccoli, A; Costa, F; Penon, G; Naccarato, R

1987-08-01

The endoscopic diagnosis of chronic atrophic gastritis is often underestimated, and most of the procedures adopted to increase diagnostic accuracy are time consuming and complex. In this study, we evaluated the usefulness of the determination of gastric juice pH by means of litmus paper. Values obtained by this method correlate well with gastric acid secretory capacity as measured by gastric acid analysis (r = -0.64, p less than 0.001) and are not affected by the presence of bile. Gastric juice pH determination increases sensitivity and other diagnostic parameters such as performance index (Youden J test), positive predictive value, and post-test probability difference by 50%. Furthermore, the negative predictive value is very high, the probability of missing a patient with chronic atrophic gastritis with this simple method being 2% for fundic and 15% for antral atrophic change. We conclude that gastric juice pH determination, which substantially increases diagnostic accuracy and is very simple to perform, should be routinely adopted.

Water-soluble pH-responsive dendritic core-shell nanocarriers for polar dyes based on poly(ethylene imine).

PubMed

Xu, Shangjie; Luo, Ying; Haag, Rainer

2007-08-07

A simple general synthetic concept to build dendritic core-shell architectures with pH-labile linkers based on hyperbranched PEI cores and biocompatible PEG shells is presented. Using these dendritic core-shell architectures as nanocarriers, the encapsulation and transport of polar dyes of different sizes is studied. The results show that the acid-labile nanocarriers exhibit much higher transport capacities for dyes than unfunctionalized hyperbranched PEI. The cleavage of imine bonds and controlled release of the polar dyes revealed that weak acidic condition (pH approximately 5.0) could cleave the imine bonds linker and release the dyes up to five times faster than neutral conditions (pH = 7.4).

A Simple Method to Estimate Photosynthetic Radiation Use Efficiency of Canopies

PubMed Central

ROSATI, A.; METCALF, S. G.; LAMPINEN, B. D.

2004-01-01

• Background and Aims Photosynthetic radiation use efficiency (PhRUE) over the course of a day has been shown to be constant for leaves throughout a general canopy where nitrogen content (and thus photosynthetic properties) of leaves is distributed in relation to the light gradient. It has been suggested that this daily PhRUE can be calculated simply from the photosynthetic properties of a leaf at the top of the canopy and from the PAR incident on the canopy, which can be obtained from weather‐station data. The objective of this study was to investigate whether this simple method allows estimation of PhRUE of different crops and with different daily incident PAR, and also during the growing season. • Methods The PhRUE calculated with this simple method was compared with that calculated with a more detailed model, for different days in May, June and July in California, on almond (Prunus dulcis) and walnut (Juglans regia) trees. Daily net photosynthesis of 50 individual leaves was calculated as the daylight integral of the instantaneous photosynthesis. The latter was estimated for each leaf from its photosynthetic response to PAR and from the PAR incident on the leaf during the day. • Key Results Daily photosynthesis of individual leaves of both species was linearly related to the daily PAR incident on the leaves (which implies constant PhRUE throughout the canopy), but the slope (i.e. the PhRUE) differed between the species, over the growing season due to changes in photosynthetic properties of the leaves, and with differences in daily incident PAR. When PhRUE was estimated from the photosynthetic light response curve of a leaf at the top of the canopy and from the incident radiation above the canopy, obtained from weather‐station data, the values were within 5 % of those calculated with the more detailed model, except in five out of 34 cases. • Conclusions The simple method of estimating PhRUE is valuable as it simplifies calculation of canopy photosynthesis to a multiplication between the PAR intercepted by the canopy, which can be obtained with remote sensing, and the PhRUE calculated from incident PAR, obtained from standard weather‐station data, and from the photosynthetic properties of leaves at the top of the canopy. The latter properties are the sole crop parameters needed. While being simple, this method describes the differences in PhRUE related to crop, season, nutrient status and daily incident PAR. PMID:15044212

The isoelectric point/point-of zero-charge of interfaces formed by aqueous solutions and nonpolar solids, liquids, and gases.

PubMed

Healy, Thomas W; Fuerstenau, Douglas W

2007-05-01

From our previous work on the role of the electrostatic field strength in controlling the pH of the iso-electric point (iep)/point-of-zero-charge (pzc) of polar solids we have extended the analysis to predict that the pH of the iep/pzc of a nonpolar solid, liquid or gas-aqueous interface should occur at pH 1.0-3.0, dependent on the value assigned to water molecules or clusters at the interface. Consideration of a wide range of experimental results covering nonpolar solids such as molybdenite, stibnite, paraffin, etc. as well as hydrocarbon liquids such as xylene, decalin, and long chain (>C8) alkane oils, as well as nitrogen and hydrogen gases, all in various simple 1:1 electrolyte solutions confirm the general validity of the result. We further consider various models of the origin of the charge on nonpolar material-water interfaces.

Superior magnetic properties of Ni ferrite nanoparticles synthesized by capping agent-free one-step coprecipitation route at different pH values

NASA Astrophysics Data System (ADS)

Iranmanesh, P.; Tabatabai Yazdi, Sh.; Mehran, M.; Saeednia, S.

2018-03-01

In this work, well-dispersed nanoparticles of NiFe2O4 with diameters less than 10 nm and good crystallinity and excellent magnetic properties were synthesized via a simple one-step capping agent-free coprecipitation route from metal chlorides. The ammonia was used as the precipitating agent and also the solution basicity controller. The effect of pH value during the coprecipitation process was investigated by details through microstructural, optical and magnetic characterizations of the synthesized particles using X-ray diffraction, transmission electron microscopy, Fourier transform infrared and UV-vis spectroscopy, and vibrating sample magnetometer. The results showed that the particle size, departure from the inverse spinel structure, the band gap value and the magnetization of Ni ferrite samples increase with pH value from 9 to 11 indicating the more pronounced surface effects in the smaller nanoparticles.

Effect of protonation on the electronic properties of DNA base pairs: applications for molecular electronics.

PubMed

Mallajosyula, Sairam S; Pati, Swapan K

2007-10-11

Protonation of DNA basepairs is a reversible phenomenon that can be controlled by tuning the pH of the system. Under mild acidic conditions, the hydrogen-bonding pattern of the DNA basepairs undergoes a change. We study the effect of protonation on the electronic properties of the DNA basepairs to probe for possible molecular electronics applications. We find that, under mild acidic pH conditions, the A:T basepair shows excellent rectification behavior that is, however, absent in the G:C basepair. The mechanism of rectification has been discussed using a simple chemical potential model. We also consider the noncanonical A:A basepair and find that it can be used as efficient pH dependent molecular switch. The switching action in the A:A basepair is explained in the light of pi-pi interactions, which lead to efficient delocalization over the entire basepair.

Microneedle pH Sensor: Direct, Label-Free, Real-Time Detection of Cerebrospinal Fluid and Bladder pH.

PubMed

Mani, Ganesh Kumar; Miyakoda, Kousei; Saito, Asuka; Yasoda, Yutaka; Kajiwara, Kagemasa; Kimura, Minoru; Tsuchiya, Kazuyoshi

2017-07-05

Acid-base homeostasis (body pH) inside the body is precisely controlled by the kidneys and lungs and buffer systems, such that even a minor pH change could severely affect many organs. Blood and urine pH tests are common in day-to-day clinical trials and require little effort for diagnosis. There is always a great demand for in vivo testing to understand more about body metabolism and to provide effective diagnosis and therapy. In this article, we report the simple fabrication of microneedle-based direct, label-free, and real-time pH sensors. The reference and working electrodes were Ag/AgCl thick films and ZnO thin films on tungsten (W) microneedles, respectively. The morphological and structural characteristics of microneedles were carefully investigated through various analytical methods. The developed sensor exhibited a Nernstian response of -46 mV/pH. Different conditions were used to test the sensor to confirm their accuracy and stability, such as various buffer solutions, with respect to time, and we compared the reading with commercial pH electrodes. Besides that, the fabricated microneedle sensor ability is proven by in vivo testing in mouse cerebrospinal fluid (CSF) and bladders. The pH sensor procedure reported here is totally reversible, and results were reproducible after several rounds of testing.

Direct Estimation of Local pH Change at Infection Sites of Fungi in Potato Tubers.

PubMed

Tardi-Ovadia, R; Linker, R; Tsror Lahkim, L

2017-01-01

Fungi can modify the pH in or around the infected site via alkalization or acidification, and pH monitoring may provide valuable information on host-fungus interactions. The objective of the present study was to examine the ability of two fungi, Colletotrichum coccodes and Helminthosporium solani, to modify the pH of potato tubers during artificial inoculation in situ. Both fungi cause blemishes on potato tubers, which downgrades tuber quality and yield. Direct visualization and estimation of pH changes near the inoculation area were achieved using pH indicators and image analysis. The results showed that the pH of the area infected by either fungus increased from potato native pH of approximately 6.0 to 7.4 to 8.0. By performing simple analysis of the images, it was also possible to derive the growth curve of each fungus and estimate the lag phase of the radial growth: 10 days for C. coccodes and 17 days H. solani. In addition, a distinctive halo (an edge area with increased pH) was observed only during the lag phase of H. solani infection. pH modulation is a major factor in pathogen-host interaction and the proposed method offers a simple and rapid way to monitor these changes.

Superlattice photonic crystal as broadband solar absorber for high temperature operation.

PubMed

Rinnerbauer, Veronika; Shen, Yichen; Joannopoulos, John D; Soljačić, Marin; Schäffler, Friedrich; Celanovic, Ivan

2014-12-15

A high performance solar absorber using a 2D tantalum superlattice photonic crystal (PhC) is proposed and its design is optimized for high-temperature energy conversion. In contrast to the simple lattice PhC, which is limited by diffraction in the short wavelength range, the superlattice PhC achieves solar absorption over broadband spectral range due to the contribution from two superposed lattices with different cavity radii. The superlattice PhC geometry is tailored to achieve maximum thermal transfer efficiency for a low concentration system of 250 suns at 1500 K reaching 85.0% solar absorptivity. In the high concentration case of 1000 suns, the superlattice PhC absorber achieves a solar absorptivity of 96.2% and a thermal transfer efficiency of 82.9% at 1500 K, amounting to an improvement of 10% and 5%, respectively, versus the simple square lattice PhC absorber. In addition, the performance of the superlattice PhC absorber is studied in a solar thermophotovoltaic system which is optimized to minimize absorber re-emission by reducing the absorber-to-emitter area ratio and using a highly reflective silver aperture.

A new device for simple and accurate urinary pH testing by the Stone-former patient.

PubMed

Grases, Felix; Rodriguez, Adrian; Berga, Francisco; Costa-Bauza, Antonia; Prieto, Rafael Maria; Burdallo, Isabel; Cadarso, Alfredo; Jimenez-Jorquera, Cecilia; Baldi, Antonio; Garganta, Rosendo

2014-01-01

Urinary pH is an important factor linked to renal stone disease and a useful marker in the treatment of urolithiasis. Although the gold standard for measuring urinary pH utilizes a glass electrode and a pH meter, at present dipstick testing is largely used to estimate urinary pH. However, the accuracy and precision of this method may be insufficient for making clinical decisions in patients with lithiasis. The aim of this study is to describe a new device for urinary pH testing. The device includes a pH sensor based on differential measurement of an ISFET-REFET pair. The drawbacks associated with this type of configuration, namely short lifetime and manual fabrication, have been overcome in the prototype. An automatic one point calibration is performed when turning on the system. Two buffer solutions were utilized to determine the intra- and inter-day precision of the device. The pH of 30 fresh human urine samples was measured using a pH-meter, a dipstick and the new electronic device. In some cases, dipstick measurements differed from those of the pH meter by more than 0.40 units, a clinically relevant discrepancy, whereas none of the measurements made with the new electronic device differed from the results of the pH-meter by more than 0.1 pH units. This new electronic device has the possibility to be used by stone-formers to control their urinary pH at home, increasing the tools available for stone prevention and prophylaxis.

pH-dependent and pH-independent self-assembling behavior of surfactant-like peptides

NASA Astrophysics Data System (ADS)

Gurevich, Leonid; Fojan, Peter

2012-02-01

Self-assembly of amphiphilic peptides designed during the last years by several research groups leads to a large variety of 3D-structures that already found applications in stabilization of large protein complexes, cell culturing systems etc. In this report, we present synthesis and characterization of two novel families of amphiphilic peptides KAn and KAnW (n=6,5,4) that exhibits clear charge separation controllable by pH of the environment. As the pH changes from acidic to basic, the charge on the ends of the peptide molecule varies eventually leading to reorganization of KAn micelles and even micellar inversion. On contrary, the bulky geometry of the tryptophan residue in KAnW limits the variation of the surfactant parameter and hence largely prevents assembly into spherical or cylindrical micelles while favouring flatter geometries. The studied short peptide families demonstrate formation of ordered aggregates with well-defined secondary structure from short unstructured peptides and provide a simple system where factors responsible for self-assembly can be singled out and studied one by one. The ability to control the shape and structure of peptide aggregates can provide basis for novel designer pH sensitive materials including drug delivery and controlled release systems.

A cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing.

PubMed

Ke, Guoliang; Zhu, Zhi; Wang, Wei; Zou, Yuan; Guan, Zhichao; Jia, Shasha; Zhang, Huimin; Wu, Xuemeng; Yang, Chaoyong James

2014-09-10

Accurate sensing of the extracellular pH is a very important yet challenging task in biological and clinical applications. This paper describes the development of an amphiphilic lipid-DNA molecule as a simple yet useful cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing. The lipid-DNA probe, which consists of a hydrophobic diacyllipid tail and a hydrophilic DNA strand, is modified with two fluorescent dyes; one is pH-sensitive as pH indicator and the other is pH-insensitive as an internal reference. The lipid-DNA probe showed sensitive and reversible response to pH change in the range of 6.0-8.0, which is suitable for most extracellular studies. In addition, based on simple hydrophobic interactions with the cell membrane, the lipid-DNA probe can be easily anchored on the cell surface with negligible cytotoxicity, excellent stability, and unique ratiometric readout, thus ensuring its accurate sensing of extracellular pH. Finally, this lipid-DNA-based ratiometric pH indicator was successfully used for extracellular pH sensing of cells in 3D culture environment, demonstrating the potential applications of the sensor in biological and medical studies.

Iridium Oxide pH Sensor Based on Stainless Steel Wire for pH Mapping on Metal Surface

NASA Astrophysics Data System (ADS)

Shahrestani, S.; Ismail, M. C.; Kakooei, S.; Beheshti, M.; Zabihiazadboni, M.; Zavareh, M. A.

2018-03-01

A simple technique to fabricate the iridium oxide pH sensor is useful in several applications such as medical, food processing and engineering material where it is able to detect the changes of pH. Generally, the fabrication technique can be classified into three types: electro-deposition iridium oxide film (EIrOF), activated iridium oxide film (AIROF) and sputtering iridium oxide film (SIROF). This study focuses on fabricating electrode, calibration and test. Electro-deposition iridium oxide film is a simple and effective method of fabricating this kind of sensor via cyclic voltammetry process. The iridium oxide thick film was successfully electrodeposited on the surface of stainless steel wire with 500 cycles of sweep potential. A further analysis under FESEM shows detailed image of iridium oxide film which has cauliflower-liked microstructure. EDX analysis shows the highest element present are iridium and oxygen which concluded that the process is successful. The iridium oxide based pH sensor has shown a good performance in comparison to conventional glass pH sensor when it is being calibrated in buffer solutions with 2, 4, 7 and 9 pH values. The iridium oxide pH sensor is specifically designed to measure the pH on the surface of metal plate.

Conformational stability of apoflavodoxin.

PubMed Central

Genzor, C. G.; Beldarraín, A.; Gómez-Moreno, C.; López-Lacomba, J. L.; Cortijo, M.; Sancho, J.

1996-01-01

Flavodoxins are alpha/beta proteins that mediate electron transfer reactions. The conformational stability of apoflavodoxin from Anaboena PCC 7119 has been studied by calorimetry and urea denaturation as a function of pH and ionic strength. At pH > 12, the protein is unfolded. Between pH 11 and pH 6, the apoprotein is folded properly as judged from near-ultraviolet (UV) circular dichroism (CD) and high-field 1H NMR spectra. In this pH interval, apoflavodoxin is a monomer and its unfolding by urea or temperature follows a simple two-state mechanism. The specific heat capacity of unfolding for this native conformation is unusually low. Near its isoelectric point (3.9), the protein is highly insoluble. At lower pH values (pH 3.5-2.0), apoflavodoxin adopts a conformation with the properties of a molten globule. Although apoflavodoxin at pH 2 unfolds cooperatively with urea in a reversible fashion and the fluorescence and far-UV CD unfolding curves coincide, the transition midpoint depends on the concentration of protein, ruling out a simple two-state process at acidic pH. Apoflavodoxin constitutes a promising system for the analysis of the stability and folding of alpha/beta proteins and for the study of the interaction between apoflavoproteins and their corresponding redox cofactors. PMID:8819170

Salivary protein concentration, flow rate, buffer capacity and pH estimation: A comparative study among young and elderly subjects, both normal and with gingivitis and periodontitis.

PubMed

Shaila, Mulki; Pai, G Prakash; Shetty, Pushparaj

2013-01-01

To evaluate the salivary protein concentration in gingivitis and periodontitis patients and compare the parameters like salivary total protein, salivary albumin, salivary flow rate, pH, buffer capacity and flow rate in both young and elderly patients with simple methods. One hundred and twenty subjects were grouped based on their age as young and elderly. Each group was subgrouped (20 subjects) as controls, gingivitis and periodontitis. Unstimulated whole saliva was collected from patients and flow rate was noted down during collection of the sample. Salivary protein estimation was done using the Biuret method and salivary albumin was assessed using the Bromocresol green method. pH was estimated with a pHmeter and buffering capacity was analyzed with the titration method. Student's t-test, Fisher's test (ANOVA) and Tukey HSD (ANOVA) tests were used for statistical analysis. A very highly significant rise in the salivary total protein and albumin concentration was noted in gingivitis and periodontitis subjects of both young and elderly. An overall decrease in salivary flow rate was observed among the elderly, and also the salivary flow rate of women was significantly lower than that of men. Significant associations between salivary total protein and albumin in gingivitis and periodontitis were found with simple biochemical tests. A decrease in salivary flow rate among elderly and among women was noted.

High performance flexible pH sensor based on carboxyl-functionalized and DEP aligned SWNTs

NASA Astrophysics Data System (ADS)

Liu, Lu; Shao, Jinyou; Li, Xiangming; Zhao, Qiang; Nie, Bangbang; Xu, Chuan; Ding, Haitao

2016-11-01

The detection and control of the pH is very important in many biomedical and chemical reaction processes. A miniaturized flexible pH sensor that is light weight, robust, and conformable is very important in many applications, such as multifunctional lab-on-a-chip systems or wearable biomedical devices. In this work, we demonstrate a flexible chemiresistive pH sensor based on dielectrophoresis (DEP) aligned carboxyl-functionalized single-walled carbon nanotubes (SWNTs). Decorated carboxyl groups can react with hydrogen (H+) and hydroxide (OH-) ions, enabling the sensor to be capable of sensing the pH. DEP is used to deposit well-organized and highly aligned SWNTs in desired locations, which improves the metal-nanotube interface and highly rapid detection of the pH, resulting in better overall device performance. When pH buffer solutions are dropped onto such SWNTs, the H+ and OH- ions caninteract with the carboxyl groups and affect the generation of holes and electrons in the SWNTs, leading to resistance variations in the SWNTs. The results shows that the relative resistance variations of the sensor increases linearly with increasing the pH values in the range from 5 to 9 and the response time ranges from 0.2 s to 22.6 s. The pH sensor also shows high performance in mechanical bendability, which benefited from the combination of flexible PET substrates and SWNTs. The SWNT-based flexible pH sensor demonstrates great potential in a wide range of areas due to its simple structure, excellent performance, low power consumption, and compatibility with integrated circuits.

Comparing Serum Follicle-Stimulating Hormone (FSH) Level with Vaginal PH in Women with Menopausal Symptoms.

PubMed

Vahidroodsari, Fatemeh; Ayati, Seddigheh; Yousefi, Zohreh; Saeed, Shohreh

2010-01-01

Despite the important implication for women's health and reproduction, very few studies have focused on vaginal PH for menopausal diagnosis. Recent studies have suggested vaginal PH as a simple, noninvasive and inexpensive method for this purpose. The aim of this study is to compare serum FSH level with vaginal PH in menopause. This is a cross-sectional, descriptive study, conducted on 103 women (aged 31-95 yrs) with menopausal symptoms who were referred to the Menopausal Clinic at Ghaem Hospital during 2006. Vaginal pH was measured using pH meter strips and serum FSH levels were measured using immunoassay methods. The data was analyzed using SPSS software (version 11.5) and results were evaluated statistically by the Chi-square and Kappa tests. p≤0.05 was considered statistically significant. According to this study, in the absence of vaginal infection, the average vaginal pH in these 103 menopausal women was 5.33±0.53. If the menopausal hallmark was considered as vaginal pH>4.5, and serum FSH as ≥20 mIU/ml, then the sensitivity of vaginal pH for menopausal diagnosis was 97%. The mean of FSH levels in this population was 80.79 mIU/ml. Vaginal pH is a simple, accurate, and cost effective tool that can be suggested as a suitable alternative to serum FSH measurement for the diagnosis of menopause.

Cancer Data and Statistics Tools

MedlinePlus

... Joseph Jacqueline W. Miller Mona Saraiya Judith Lee Smith Sherri L. Stewart Mary C. White Debra Younginer ... MD, MPH Simple Singh, MD, MPH Judith Lee Smith, PhD Sherri L. Stewart, PhD Eric Tai, MD, ...

Stability of a pH-sensitive polymer matrix

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

Northrup, M.A.; Langry, K.; Angel, S.M.

1990-03-01

A ratiometric pH-sensitive fluorescent dye (hydroxypyrenetrisulfonic acid) was covalently attached to an acrylamide polymer. These pH-sensitive copolymers were either covalently bonded to the end of an optical fiber or polymerized into separate gels. Long-term, accelerated aging studies were performed on the fibers and gels in 43{degree}C distilled H{sub 2}O. The fiber-immobilized optrodes gave good pH responses for up to 2 months. The pH-sensitive gels were physically attached to optical fibers and gave very good pH responses for over one year. These physically immobilized, one-year-old, pH-sensitive copolymers provided optrodes with linear pH responses between pH 6 and 8 and resolution greatermore » than 0.25 pH unit. A simple photostability experiment on these optrodes showed that they were very photostable. The results of this study indicate that pH-sensitive copolymers in a simple optrode design can be employed as pH sensors with useful lifetimes exceeding one year. 11 refs., 6 figs.« less

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors.

PubMed

Yang, Jiang; Kwak, Tae-Joon; Zhang, Xiaodong; McClain, Robert; Chang, Woo-Jin; Gunasekaran, Sundaram

2016-11-22

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (µPAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

Mathematical model for steady state, simple ampholyte isoelectric focusing: Development, computer simulation and implementation

NASA Technical Reports Server (NTRS)

Palusinski, O. A.; Allgyer, T. T.

1979-01-01

The elimination of Ampholine from the system by establishing the pH gradient with simple ampholytes is proposed. A mathematical model was exercised at the level of the two-component system by using values for mobilities, diffusion coefficients, and dissociation constants representative of glutamic acid and histidine. The constants assumed in the calculations are reported. The predictions of the model and computer simulation of isoelectric focusing experiments are in direct importance to obtain Ampholine-free, stable pH gradients.

Teaching Plant-Soil Relationships with Color Images of Rhizosphere pH.

ERIC Educational Resources Information Center

Heckman, J. R.; Strick, J. E.

1996-01-01

Presents a laboratory exercise that uses a simple imaging technique to illustrate the profound effects that living roots exert on the pH of the surrounding soil environment. Achieves visually stimulating results that can be used to reinforce lectures on rhizosphere pH, nutrient availability, plant tolerance of soil acidity, microbial activity, and…

Monitoring and control of the biogas process based on propionate concentration using online VFA measurement.

PubMed

Boe, Kanokwan; Steyer, Jean-Philippe; Angelidaki, Irini

2008-01-01

Simple logic control algorithms were tested for automatic control of a lab-scale CSTR manure digester. Using an online VFA monitoring system, propionate concentration in the reactor was used as parameter for control of the biogas process. The propionate concentration was kept below a threshold of 10 mM by manipulating the feed flow. Other online parameters such as pH, biogas production, total VFA, and other individual VFA were also measured to examine process performance. The experimental results showed that a simple logic control can successfully prevent the reactor from overload, but with fluctuations of the propionate level due to the nature of control approach. The fluctuation of propionate concentration could be reduced, by adding a lower feed flow limit into the control algorithm to prevent undershooting of propionate response. It was found that use of the biogas production as a main control parameter, rather than propionate can give a more stable process, since propionate was very persistent and only responded very slowly to the decrease of the feed flow which lead to high fluctuation of biogas production. Propionate, however, was still an excellent parameter to indicate process stress under gradual overload and thus recommended as an alarm in the control algorithm. Copyright IWA Publishing 2008.

The fate of silicon during glass corrosion under alkaline conditions: A mechanistic and kinetic study with the International Simple Glass

NASA Astrophysics Data System (ADS)

Gin, Stéphane; Jollivet, Patrick; Fournier, Maxime; Berthon, Claude; Wang, Zhaoying; Mitroshkov, Alexandre; Zhu, Zihua; Ryan, Joseph V.

2015-02-01

International Simple Glass - a six oxide borosilicate glass selected by the international nuclear glass community to improve the understanding of glass corrosion mechanisms and kinetics - was altered at 90 °C in a solution initially saturated with respect to amorphous 29SiO2. The pH90°C, was fixed at 9 at the start of the experiment and raised to 11.5 after 209 d by the addition of KOH. Isotope sensitive analytical techniques were used to analyze the solution and altered glass samples, helping to understand the driving forces and rate limiting processes controlling long-term glass alteration. At pH 9, the corrosion rate continuously drops and the glass slowly transforms into a uniform, homogeneous amorphous alteration layer. The mechanisms responsible for this transformation are water penetration through the growing alteration layer and ion exchange. We demonstrate that this amorphous alteration layer is not a precipitate resulting from the hydrolysis of the silicate network; it is mostly inherited from the glass structure from which the most weakly bonded cations (Na, Ca and B) have been released. At pH 11.5, the alteration process is very different: the high solubility of glass network formers (Si, Al, Zr) triggers the rapid and complete dissolution of the glass (dissolution becomes congruent) and precipitation of amorphous and crystalline phases. Unlike at pH 9 where glass corrosion rate decreased by 3 orders of magnitude likely due to the retroaction of the alteration layer on water dynamics/reactivity at the reaction front, the rate at pH 11.5 is maintained at a value close to the forward rate due to both the hydrolysis of the silicate network promoted by OH- and the precipitation of CSH and zeolites. This study provides key information for a unified model for glass dissolution.

Building a polysaccharide hydrogel capsule delivery system for control release of ibuprofen.

PubMed

Chen, Zhi; Wang, Ting; Yan, Qing

2018-02-01

Development of a delivery system which can effectively carry hydrophobic drugs and have pH response is becoming necessary. Here we demonstrate that through preparation of β-cyclodextrin polymer (β-CDP), a hydrophobic drug molecule of ibuprofen (IBU) was incorporated into our prepared β-CDP inner cavities, aiming to improve the poor water solubility of IBU. A core-shell capsule structure has been designed for achieving the drug pH targeted and sustained release. This delivery system was built with polysaccharide polymer of Sodium alginate (SA), sodium carboxymethylcellulose (CMC) and hydroxyethyl cellulose (HEC) by physical cross-linking. The drug pH-response control release is this hydrogel system's chief merit, which has potential value for synthesizing enteric capsule. Besides, due to our simple preparing strategy, optimal conditions can be readily determined and the synthesis process can be accurately controlled, leading to consistent and reproducible hydrogel capsules. In addition, phase-solubility method was used to investigate the solubilization effect of IBU by β-CDP. SEM was used to prove the forming of core and shell structure. FT-IR and 1 H-NMR were also used to perform structural characteristics. By the technique of UV determination, the pH targeted and sustained release study were also performed. The results have proved that our prepared polysaccharide hydrogel capsule delivery system has potential applications as oral drugs delivery in the field of biomedical materials.

Amine-free reversible hydrogen storage in formate salts catalyzed by ruthenium pincer complex without pH control or solvent change.

PubMed

Kothandaraman, Jotheeswari; Czaun, Miklos; Goeppert, Alain; Haiges, Ralf; Jones, John-Paul; May, Robert B; Prakash, G K Surya; Olah, George A

2015-04-24

Due to the intermittent nature of most renewable energy sources, such as solar and wind, energy storage is increasingly required. Since electricity is difficult to store, hydrogen obtained by electrochemical water splitting has been proposed as an energy carrier. However, the handling and transportation of hydrogen in large quantities is in itself a challenge. We therefore present here a method for hydrogen storage based on a CO2 (HCO3 (-) )/H2 and formate equilibrium. This amine-free and efficient reversible system (>90 % yield in both directions) is catalyzed by well-defined and commercially available Ru pincer complexes. The formate dehydrogenation was triggered by simple pressure swing without requiring external pH control or the change of either the solvent or the catalyst. Up to six hydrogenation-dehydrogenation cycles were performed and the catalyst performance remained steady with high selectivity (CO free H2 /CO2 mixture was produced). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Au38(SCH2CH2Ph)24, Au36(SPh-tBu)24, and Au30(S-tBu)18 Nanomolecules from a Common Precursor Mixture.

PubMed

Rambukwella, Milan; Dass, Amala

2017-10-17

Phenylethanethiol protected nanomolecules such as Au 25 , Au 38 , and Au 144 are widely studied by a broad range of scientists in the community, owing primarily to the availability of simple synthetic protocols. However, synthetic methods are not available for other ligands, such as aromatic thiol and bulky ligands, impeding progress. Here we report the facile synthesis of three distinct nanomolecules, Au 38 (SCH 2 CH 2 Ph) 24 , Au 36 (SPh-tBu) 24 , and Au 30 (S-tBu) 18 , exclusively, starting from a common Au n (glutathione) m (where n and m are number of gold atoms and glutathiolate ligands) starting material upon reaction with HSCH 2 CH 2 Ph, HSPh-tBu, and HStBu, respectively. The systematic synthetic approach involves two steps: (i) synthesis of kinetically controlled Au n (glutathione) m crude nanocluster mixture with 1:4 gold to thiol molar ratio and (ii) thermochemical treatment of the purified nanocluster mixture with excess thiols to obtain thermodynamically stable nanomolecules. Thermochemical reactions with physicochemically different ligands formed highly monodispersed, exclusively three different core-size nanomolecules, suggesting a ligand induced core-size conversion and structural transformation. The purpose of this work is to make available a facile and simple synthetic method for the preparation of Au 38 (SCH 2 CH 2 Ph) 24 , Au 36 (SPh-tBu) 24 , and Au 30 (S-tBu) 18 , to nonspecialists and the broader scientific community. The central idea of simple synthetic method was demonstrated with other ligand systems such as cyclopentanethiol (HSC 5 H 9 ), cyclohexanethiol(HSC 6 H 11 ), para-methylbenzenethiol(pMBT), 1-pentanethiol(HSC 5 H 11 ), 1-hexanethiol(HSC 6 H 13 ), where Au 36 (SC 5 H 9 ) 24 , Au 36 (SC 6 H 11 ) 24 , Au 36 (pMBT) 24 , Au 38 (SC 5 H 11 ) 24 , and Au 38 (SC 6 H 13 ) 24 were obtained, respectively.

Lightning Physics: A Three Year Program

DTIC Science & Technology

1983-01-01

because these aircraft are controlled poeal’ r r o(z’, I- RIC) with low-voltage digital electronics and are in part construct- 4w J(,3 cR "*t • at ed of... millise - limits pretrigger and delayed-trigger mode,. and a variety of sample conds, and hundreds of microseconds, respectively, the time of simple...processes, but we feel it prudent to discontinue use of the Proctor, D. E., A radio study of lightning, Ph.D. thesis , Univ. of designations in order

Teaching pH Measurements with a Student-Assembled Combination Quinhydrone Electrode

ERIC Educational Resources Information Center

Scholz, Fritz; Steinhardt, Tim; Kahlert, Heike; Porksen, Jens R.; Behnert, Jurgen

2005-01-01

A simple combination pH electrode consisting of a solid-state quinhydrone sensor and a solid-state quinhydrone reference electrode is described. Both electrodes are essentially rubber stoppers that are inserted into a special doublewalled holder.

Intracellular pH measurements made simple by fluorescent protein probes and the phasor approach to fluorescence lifetime imaging†

PubMed Central

Digman, Michelle A.; Gratton, Enrico; Storti, Barbara; Beltram, Fabio

2013-01-01

A versatile pH-dependent fluorescent protein was applied to intracellular pH measurements by means of the phasor approach to fluorescence lifetime imaging. By this fit-less method we obtain intracellular pH maps under resting or altered physiological conditions by single-photon confocal or two-photon microscopy. PMID:22517076

CADDIS Volume 2. Sources, Stressors and Responses: Simple and Detailed Conceptual Model Diagram Downloads

EPA Pesticide Factsheets

Simple and detailed conceptual model diagram and associated narrative for ammonia, dissolved oxygen, flow alteration, herbicides, insecticides, ionic strength, metals, nutrients, ph, physical habitat, sediments, temperature, unspecified toxic chemicals.

Describing temporal variation in reticuloruminal pH using continuous monitoring data.

PubMed

Denwood, M J; Kleen, J L; Jensen, D B; Jonsson, N N

2018-01-01

Reticuloruminal pH has been linked to subclinical disease in dairy cattle, leading to considerable interest in identifying pH observations below a given threshold. The relatively recent availability of continuously monitored data from pH boluses gives new opportunities for characterizing the normal patterns of pH over time and distinguishing these from abnormal patterns using more sensitive and specific methods than simple thresholds. We fitted a series of statistical models to continuously monitored data from 93 animals on 13 farms to characterize normal variation within and between animals. We used a subset of the data to relate deviations from the normal pattern to the productivity of 24 dairy cows from a single herd. Our findings show substantial variation in pH characteristics between animals, although animals within the same farm tended to show more consistent patterns. There was strong evidence for a predictable diurnal variation in all animals, and up to 70% of the observed variation in pH could be explained using a simple statistical model. For the 24 animals with available production information, there was also a strong association between productivity (as measured by both milk yield and dry matter intake) and deviations from the expected diurnal pattern of pH 2 d before the productivity observation. In contrast, there was no association between productivity and the occurrence of observations below a threshold pH. We conclude that statistical models can be used to account for a substantial proportion of the observed variability in pH and that future work with continuously monitored pH data should focus on deviations from a predictable pattern rather than the frequency of observations below an arbitrary pH threshold. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A simple and rapid approach to evaluate the in vitro in vivo role of release controlling agent ethyl cellulose ether derivative polymer.

PubMed

Akhlaq, Muhammad; Khan, Gul Majid; Jan, Syed Umer; Wahab, Abdul; Hussain, Abid; Nawaz, Asif; Abdelkader, Hamdy

2014-11-01

Diclofenac sodium (DCL-Na) conventional oral tablets exhibit serious side effects when given for a longer period leading to noncompliance. Controlled release matrix tablets of diclofenac sodium were formulated using simple blending (F-1), solvent evaporation (F-2) and co-precipitation techniques (F-3). Ethocel® Standard 7 FP Premium Polymer (15%) was used as a release controlling agent. Drug release study was conducted in 7.4 pH phosphate buffer solutions as dissolution medium in vitro. Pharmacokinetic parameters were evaluated using albino rabbits. Solvent evaporation technique was found to be the best release controlling technique thereby prolonging the release rate up to 24 hours. Accelerated stability studies of the optimized test formulation (F-2) did not show any significant change (p<0.05) in the physicochemical characteristics and release rate when stored for six months. A simple and rapid method was developed for DCL-Na active moiety using HPLC-UV at 276nm. The optimized test tablets (F-2) significantly (p<0.05) exhibited peaks plasma concentration (cmax=237.66±1.98) and extended the peak time (tmax=4.63±0.24). Good in-vitro in vivo correlation was found (R(2)=0.9883) against drug absorption and drug release. The study showed that once-daily controlled release matrix tablets of DCL-Na were successfully developed using Ethocel® Standard 7 FP Premium.

Retention and release of oil-in-water emulsions from filled hydrogel beads composed of calcium alginate: impact of emulsifier type and pH.

PubMed

Zeeb, Benjamin; Saberi, Amir Hossein; Weiss, Jochen; McClements, David Julian

2015-03-21

Delivery systems based on filled hydrogel particles (microgels) can be fabricated from natural food-grade lipids and biopolymers. The potential for controlling release characteristics by modulating the electrostatic interactions between emulsifier-coated lipid droplets and the biopolymer matrix within hydrogel particles was investigated. A multistage procedure was used to fabricate calcium alginate beads filled with lipid droplets stabilized by non-ionic, cationic, anionic, or zwitterionic emulsifiers. Oil-in-water emulsions stabilized by Tween 60, DTAB, SDS, or whey protein were prepared by microfluidization, mixed with various alginate solutions, and then microgels were formed by simple extrusion into calcium solutions. The microgels were placed into a series of buffer solutions with different pH values (2 to 11). Lipid droplets remained encapsulated under acidic and neutral conditions, but were released under highly basic conditions (pH 11) due to hydrogel swelling when the alginate concentration was sufficiently high. Lipid droplet release increased with decreasing alginate concentration, which could be attributed to an increase in the pore size of the hydrogel matrix. These results have important implications for the design of delivery systems to entrap and control the release of lipophilic bioactive components within filled hydrogel particles.

Alginate/sodium caseinate aqueous-core capsules: a pH-responsive matrix.

PubMed

Ben Messaoud, Ghazi; Sánchez-González, Laura; Jacquot, Adrien; Probst, Laurent; Desobry, Stéphane

2015-02-15

Alginate capsules have several applications. Their functionality depends considerably on their permeability, chemical and mechanical stability. Consequently, the creation of composite system by addition of further components is expected to control mechanical and release properties of alginate capsules. Alginate and alginate-sodium caseinate composite liquid-core capsules were prepared by a simple extrusion. The influence of the preparation pH and sodium caseinate concentration on capsules physico-chemical properties was investigated. Results showed that sodium caseinate influenced significantly capsules properties. As regards to the membrane mechanical stability, composite capsules prepared at pH below the isoelectric point of sodium caseinate exhibited the highest surface Young's modulus, increasing with protein content, explained by potential electrostatic interactions between sodium caseinate amino-groups and alginate carboxylic group. The kinetic of cochineal red A release changed significantly for composite capsules and showed a pH-responsive release. Sodium caseinate-dye mixture studied by absorbance and fluorescence spectroscopy confirmed complex formation at pH 2 by electrostatic interactions between sodium caseinate tryptophan residues and cochineal red sulfonate-groups. Consequently, the release mechanism was explained by membrane adsorption process. This global approach is useful to control release mechanism from macro and micro-capsules by incorporating guest molecules which can interact with the entrapped molecule under specific conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

Isolated p.H62L Mutation in the CYP21A2 Gene in a Simple Virilizing 21-Hydroxylase Deficient Patient

PubMed Central

Fernández, Cecilia; Belli, Susana; Buzzalino, Noemi; Dain, Liliana

2013-01-01

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency accounts for 90%–95% of cases. This autosomal recessive disorder has a broad spectrum of clinical forms, ranging from severe or classical, which includes the salt-wasting and simple virilizing forms, to the mild late onset or nonclassical form. Most of the disease-causing mutations described are likely to be the consequence of nonhomologous recombination or gene conversion events between the active CYP21A2 gene and its homologous CYP21A1P pseudogene. Nevertheless, an increasing number of naturally occurring mutations have been found. The change p.H62L is one of the most frequent rare mutations of the CYP21A2 gene. It was suggested that the p.H62L represents a mild mutation that may be responsible for a more severe enzymatic impairment when presented with another mild mutation on the same allele. In this report, a 20-year-old woman carrying an isolated p.H62L mutation in compound heterozygosity with c.283-13A/C>G mutation is described. Although a mildly nonclassical phenotype was expected, clinical signs and hormonal profile of the patient are consistent with a more severe simple virilizing form of 21-hydroxylase deficiency. The study of genotype-phenotype correlation in additional patients would help in defining the role of p.H62L in disease manifestation. PMID:23936690

Isolated p.H62L Mutation in the CYP21A2 Gene in a Simple Virilizing 21-Hydroxylase Deficient Patient.

PubMed

Taboas, Melisa; Fernández, Cecilia; Belli, Susana; Buzzalino, Noemi; Alba, Liliana; Dain, Liliana

2013-01-01

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency accounts for 90%-95% of cases. This autosomal recessive disorder has a broad spectrum of clinical forms, ranging from severe or classical, which includes the salt-wasting and simple virilizing forms, to the mild late onset or nonclassical form. Most of the disease-causing mutations described are likely to be the consequence of nonhomologous recombination or gene conversion events between the active CYP21A2 gene and its homologous CYP21A1P pseudogene. Nevertheless, an increasing number of naturally occurring mutations have been found. The change p.H62L is one of the most frequent rare mutations of the CYP21A2 gene. It was suggested that the p.H62L represents a mild mutation that may be responsible for a more severe enzymatic impairment when presented with another mild mutation on the same allele. In this report, a 20-year-old woman carrying an isolated p.H62L mutation in compound heterozygosity with c.283-13A/C>G mutation is described. Although a mildly nonclassical phenotype was expected, clinical signs and hormonal profile of the patient are consistent with a more severe simple virilizing form of 21-hydroxylase deficiency. The study of genotype-phenotype correlation in additional patients would help in defining the role of p.H62L in disease manifestation.

Generation of pH responsive fluorescent nano capsules through simple steps for the oral delivery of low pH susceptible drugs

NASA Astrophysics Data System (ADS)

Radhakumary, Changerath; Sreenivasan, Kunnatheeri

2016-11-01

pH responsive nano capsules are promising as it can encapsulate low pH susceptible drugs like insulin and guard them from the hostile environments in the intestinal tract. The strong acidity of the gastro-intestinal tract and the presence of proteolytic enzymes are the tumbling blocks for the design of drug delivery vehicles through oral route for drugs like insulin. Nano capsules are normally built over templates which are subsequently removed by further steps. Such processes are complex and often lead into deformed and collapsed capsules. In this study, we choose calcium carbonate (CaCO3) nano particles to serve as template. Over CaCO3 nanoparticles, silica layers were built followed by polymethacrylic acid chains to acquire pH responsiveness. During the polymerization process of the methacrylic acid, the calcium carbonate core particles were dissolved leading to the formation of nano hollow capsules having a size that ranges from 225 to 246 nm and thickness from 19 to 58 nm. The methodology is simple and devoid of additional steps. The nano shells exhibited 80% release of the loaded model drug, insulin at pH 7.4 while at pH 2.0 the capsules nearly stopped the release of the drug. Polymethacrylic acid shows pH responsive swelling behavior that it swells at intestinal pH (7.0-7.5) and shrinks at gastric pH (˜2.0) thus enabling the safe unloading of the drug from the nano capsules.

Gravity-driven pH adjustment for site-specific protein pKa measurement by solution-state NMR

NASA Astrophysics Data System (ADS)

Li, Wei

2017-12-01

To automate pH adjustment in site-specific protein pKa measurement by solution-state NMR, I present a funnel with two caps for the standard 5 mm NMR tube. The novelty of this simple-to-build and inexpensive apparatus is that it allows automatic gravity-driven pH adjustment within the magnet, and consequently results in a fully automated NMR-monitored pH titration without any hardware modification on the NMR spectrometer.

Preparation and characterization of glycidyl methacrylate organo bridges grafted mesoporous silica SBA-15 as ibuprofen and mesalamine carrier for controlled release.

PubMed

Rehman, Fozia; Rahim, Abdur; Airoldi, Claudio; Volpe, Pedro L O

2016-02-01

Mesoporous silica SBA-15 was synthesized and functionalized with bridged polysilsesquioxane monomers obtained by the reaction of 3-aminopropyltriethoxy silane with glycidyl methacrylate in 2:1 ratio. The synthesized mesoporous silica materials were characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance spectroscopy, nitrogen adsorption, X-ray diffraction, thermogravimetry and scanning electron microscopy. The nuclear magnetic resonance in the solid state is in agreement with the sequence of carbon distributed in the attached organic chains, as expected for organically functionalized mesoporous silica. After functionalization with organic bridges the BET surface area was reduced from 1311.80 to 494.2m(2)g(-1) and pore volume was reduced from 1.98 to 0.89cm(3)g(-1), when compared to original precursor silica. Modification of the silica surface with organic bridges resulted in high loading capacity and controlled release of ibuprofen and mesalamine in biological fluids. The Korsmeyer-Peppas model better fits the release data indicating Fickian diffusion and zero order kinetics for synthesized mesoporous silica. The drug release rate from the modified silica was slow in simulated gastric fluid, (pH1.2) where less than 10% of mesalamine and ibuprofen were released in initial 8h, while comparatively high release rates were observed in simulated intestinal (pH6.8) and simulated body fluids (pH7.2). The preferential release of mesalamine at intestinal pH suggests that the modified silica could be a simple, efficient, inexpensive and convenient carrier for colon targeted drugs, such a mesalamine and also as a controlled drug release system. Copyright © 2015 Elsevier B.V. All rights reserved.

Capture and separation of l-histidine through optimized zinc-decorated magnetic silica spheres.

PubMed

Cardoso, Vanessa F; Sebastián, Víctor; Silva, Carlos J R; Botelho, Gabriela; Lanceros-Méndez, Senentxu

2017-09-01

Zinc-decorated magnetic silica spheres were developed, optimized and tested for the capture and separation of l-histidine. The magnetic silica spheres were prepared using a simple sol-gel method and show excellent magnetic characteristics, adsorption capacity toward metal ions, and stability in aqueous solution in a wide pH range. The binding capacity of zinc-decorated magnetic silica spheres to histidine proved to be strongly influenced by the morphology, composition and concentration of metal at the surface of the magnetic silica spheres and therefore these parameters should be carefully controlled in order to maximize the performance for protein purification purposes. Optimized zinc-decorated magnetic silica spheres demonstrate a binding capacity to l-histidine of approximately 44mgg -1 at the optimum binding pH buffer. Copyright © 2017 Elsevier B.V. All rights reserved.

Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films.

PubMed

Khan, Zia Ullah; Bubnova, Olga; Jafari, Mohammad Javad; Brooke, Robert; Liu, Xianjie; Gabrielsson, Roger; Ederth, Thomas; Evans, Drew R; Andreasen, Jens W; Fahlman, Mats; Crispin, Xavier

2015-10-28

PEDOT-Tos is one of the conducting polymers that displays the most promising thermoelectric properties. Until now, it has been utterly difficult to control all the synthesis parameters and the morphology governing the thermoelectric properties. To improve our understanding of this material, we study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes in the nanoscale morphology due to anion exchange between tosylate and Cl - or OH - . But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid-base treatment allows finding the optimum for the power factor in PEDOT-Tos thin films.

Attenuation of landfill leachate by UK Triassic sandstone aquifer materials. 1. Fate of inorganic pollutants in laboratory columns

NASA Astrophysics Data System (ADS)

Thornton, Steven F.; Tellam, John H.; Lerner, David N.

2000-05-01

The attenuation of inorganic contaminants in acetogenic and methanogenic landfill leachate by calcareous and carbonate-deficient, oxide-rich Triassic sandstone aquifer materials from the English Midlands was examined in laboratory columns. Aqueous equilibrium speciation modelling, simple transport modelling and chemical mass balance approaches are used to evaluate the key processes and aquifer geochemical properties controlling contaminant fate. The results indicate that leachate-rock interactions are dominated by ion-exchange processes, acid-base and redox reactions and sorption/precipitation of metal species. Leachate NH 4 is attenuated by cation exchange with the aquifer sediments; however, NH 4 migration could be described with a simple model using retardation factors. Organic acids in the acetogenic leachate buffered the system pH at low levels during flushing of the calcareous aquifer material. In contrast, equilibrium with Al oxyhydroxide phases initially buffered pH (˜4.5) during flushing of the carbonate-deficient sandstone with methanogenic leachate. This led to the mobilisation of sorbed and oxide-bound heavy metals from the aquifer sediment which migrated as a concentrated pulse at the leachate front. Abiotic reductive dissolution of Mn oxyhydroxides on each aquifer material by leachate Fe 2+ maintains high concentrations of dissolved Mn and buffers the leachate inorganic redox system. This feature is analogous to the Mn-reducing zones found in leachate plumes and in the experiments provides a sink for the leachate Fe load and other heavy metals. The availability of reactive solid phase Mn oxyhydroxides limits the duration of redox buffering and Fe attenuation by these aquifer sediments. Aquifer pH and redox buffering capacity exert a fundamental influence on leachate inorganic contaminant fate in these systems. The implications for the assessment of aquifer vulnerability at landfills are discussed and simple measurements of aquifer properties which may improve the prediction of contaminant attenuation are outlined.

Insight into the stability of poly(diallydimethylammoniumchloride) and polybrene poly cationic coatings in capillary electrophoresis.

PubMed

Pei, Lei; Lucy, Charles A

2014-10-24

Polycationic polymers are widely used in capillary electrophoresis (CE) as surface coatings to prevent protein adsorption and control electroosmotic flow (EOF). Such semi-permanent coatings are formed by flushing the capillary with a quaternary amine-based polymer such as poly(diallydimethylammonium chloride) (PDADMAC) or polybrene. Compared to covalent capillary coatings, the claimed advantages of adsorptive polycation coatings are their simple preparation and that they are not limited to the pH 2-8 range as are covalent coatings. However, while the latter is commonly claimed, few studies have demonstrated the stability of polycationic coatings at extreme pH. Herein PDADMAC and polybrene are studied as model cationic coatings. PDADMAC with higher molecular weight (M.W.) demonstrated higher EOF stability at pH 9.5, with PDADMAC of M.W. less than 200,000 being unstable at pH 9.5. X-ray photoelectron spectroscopy (XPS) shows that the quaternary amines of PDADMAC and polybrene were slowly converted to tertiary amines in alkaline solution and more rapidly when adsorbed on a silica surface. The degraded polycation deprotonated at pH >7, resulting in loss of polymer from the surface and diminishing EOF. Successive multiple ionic layer (SMIL) coatings show greater alkaline stability by distancing the polycation from the surface. Separations of inorganic anions at pH 9.5 illustrate the degradation behavior and enhanced stability of higher M.W. polycationic coatings. Copyright © 2014 Elsevier B.V. All rights reserved.

Escherichia coli Attenuation by Fe Electrocoagulation in Synthetic Bengal Groundwater: Effect of pH and Natural Organic Matter.

PubMed

Delaire, Caroline; van Genuchten, Case M; Nelson, Kara L; Amrose, Susan E; Gadgil, Ashok J

2015-08-18

Technologies addressing both arsenic and microbial contamination of Bengal groundwater are needed. Fe electrocoagulation (Fe-EC), a simple process relying on the dissolution of an Fe(0) anode to produce Fe(III) precipitates, has been shown to efficiently remove arsenic from groundwater at low cost. We investigated Escherichia coli (E. coli) attenuation by Fe-EC in synthetic Bengal groundwater as a function of Fe dosage rate, total Fe dosed, pH, and presence of natural organic matter (NOM). A 2.5 mM Fe dosage simultaneously achieved over 4-log E. coli attenuation and arsenic removal from 450 to below 10 μg/L. E. coli reduction was significantly enhanced at pH 6.6 compared to pH 7.5, which we linked to the decreased rate of Fe(II) oxidation at lower pH. 3 mg/L-C of NOM (Suwanee River fulvic acid) did not significantly affect E. coli attenuation. Live-dead staining and comparisons of Fe-EC with chemical coagulation controls showed that the primary mechanism of E. coli attenuation is physical removal with Fe(III) precipitates, with inactivation likely contributing as well at lower pH. Transmission electron microscopy showed that EC precipitates adhere to and bridge individual E. coli cells, resulting in large bacteria-Fe aggregates that can be removed by gravitational settling. Our results point to the promising ability of Fe-EC to treat arsenic and bacterial contamination simultaneously at low cost.

General Procedure for the Easy Calculation of pH in an Introductory Course of General or Analytical Chemistry

ERIC Educational Resources Information Center

Cepriá, Gemma; Salvatella, Luis

2014-01-01

All pH calculations for simple acid-base systems used in introductory courses on general or analytical chemistry can be carried out by using a general procedure requiring the use of predominance diagrams. In particular, the pH is calculated as the sum of an independent term equaling the average pK[subscript a] values of the acids involved in the…

A water-soluble rhodamine B-derived fluorescent probe for pH monitoring and imaging in acidic regions

NASA Astrophysics Data System (ADS)

Cui, Peng; Jiang, Xuekai; Sun, Junyong; Zhang, Qiang; Gao, Feng

2017-06-01

A structurally simple, water-soluble rhodamine-derivatived fluorescent probe, which is responsive to acidic pH, was conveniently synthesized via a one-step condensation reaction of rhodamine B hydrazide and 4-formybenzene-1,3-disulfonate. As a stable and highly sensitive pH sensor, the probe displays an approximately 50-fold fluorescence enhancement over the pH range of 7.16-4.89 as the structure of probe changes from spirocyclic (weak fluorescent) to ring-open (strong fluorescent) with decreasing pH. The synthesized fluorescent probe is applied to the detection of pH changes in vitro and in vivo bioimaging of immortalized gastric cancer cells, with satisfactory results.

Polymer grafted magnetic nanoparticles for delivery of anticancer drug at lower pH and elevated temperature.

PubMed

Dutta, Sujan; Parida, Sheetal; Maiti, Chiranjit; Banerjee, Rakesh; Mandal, Mahitosh; Dhara, Dibakar

2016-04-01

Efficient and controlled delivery of therapeutics to tumor cells is one of the important issues in cancer therapy. In the present work, a series of pH- and temperature-responsive polymer grafted iron oxide nanoparticles were prepared by simple coupling of aminated iron oxide nanoparticle with poly(N-isopropylacrylamide-ran-poly(ethylene glycol) methyl ether acrylate)-block-poly(acrylic acid) (P(NIPA-r-PEGMEA)-b-PAA). For this, three water soluble block polymers were prepared via reversible addition fragmentation transfer (RAFT) polymerization technique. At first, three different block copolymers were prepared by polymerizing mixture of NIPA and PEGMEA (with varying mole ratio) in presence of poly(tert-butyl acrylate) (PtBA) macro chain transfer agent. Subsequently, P(NIPA-r-PEGMEA)-b-PAA copolymers were synthesized by hydrolyzing tert-butyl acrylate groups of the P(NIPA-r-PEGMEA)-b-PtBA copolymers. The resulting polymers were then grafted to iron oxide nanoparticles, and these functionalized nanoparticles were thoroughly characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), zeta potential measurements, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). Doxorubicin (DOX), an anti-cancer drug, was loaded into the polymer coated nanoparticles and its release behavior was subsequently studied at different pH and temperatures. The drug release pattern revealed a sustained release of DOX preferentially at the desired lysosomal pH of cancer cells (pH 5.0) and slightly above the physiological temperature depending upon the composition of the copolymers. The potential anticancer activity of the polymer grafted DOX loaded nanoparticles were established by MTT assay and apoptosis study of cervical cancer ME 180cells in presence of the nanoparticles. Thus, these particles can be utilized for controlled delivery of anticancer drugs at the desired lysosomal pH and/or by slightly heating the cells using magnetic hyperthermia. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of water pH using absorption-based optical sensors: evaluation of different calculation methods

NASA Astrophysics Data System (ADS)

Wang, Hongliang; Liu, Baohua; Ding, Zhongjun; Wang, Xiangxin

2017-02-01

Absorption-based optical sensors have been developed for the determination of water pH. In this paper, based on the preparation of a transparent sol-gel thin film with a phenol red (PR) indicator, several calculation methods, including simple linear regression analysis, quadratic regression analysis and dual-wavelength absorbance ratio analysis, were used to calculate water pH. Results of MSSRR show that dual-wavelength absorbance ratio analysis can improve the calculation accuracy of water pH in long-term measurement.

Determination of total arsenic and arsenic(III) in phosphate fertilizers by hydride generation atomic absorption spectrometry after ultrasound-assisted extraction based on a control acid media.

PubMed

Rezende, Helen Cristine; Coelho, Nivia Maria Melo

2014-01-01

An ultrasound-assisted extraction procedure was developed for determination of inorganic arsenic (As) in phosphate fertilizer by hydride generation atomic absorption spectrometry. The variables that affect the hydride generation step were optimized, including the reducer, acid, sample flow rate, and concentrations of the acid and reducer. The determination of As(lll) was performed through the simple control of solution pH with a 0.5 M citric acid-sodium citrate buffer solution at pH 4.5, and total As was determined after a pre-reduction reaction with 1.0% (w/v) thiourea. Ultrasound-assisted acid extraction was performed, and the parameters sonication time and acid and Triton X-114 concentrations were optimized using a 23 factorial design and central composite design. LODs for As(lll) and total As were 0.029 and 0.022 microg/L, respectively. The accuracy of the method was confirmed with certified reference materials. The method was successfully applied in the determination of inorganic As in phosphate fertilizer samples.

Controlled Aggregation and Increased Stability of β-Glucuronidase by Cellulose Binding Domain Fusion

PubMed Central

Kim, Moonjung; Kwon, Kil Koang; Fu, Yaoyao; Kim, Haseong; Lee, Hyewon; Lee, Dae-Hee; Jung, Heungchae; Lee, Seung-Goo

2017-01-01

Cellulose-binding domains (CBDs) are protein domains with cellulose-binding activity, and some act as leaders in the localization of cellulosomal scaffoldin proteins to the hydrophobic surface of crystalline cellulose. In this study, we found that a CBD fusion enhanced and improved soluble β-glucuronidase (GusA) enzyme properties through the formation of an artificially oligomeric state. First, a soluble CBD fused to the C-terminus of GusA (GusA-CBD) was obtained and characterized. Interestingly, the soluble GusA-CBD showed maximum activity at higher temperatures (65°C) and more acidic pH values (pH 6.0) than free GusA did (60°C and pH 7.5). Moreover, the GusA-CBD enzyme showed higher thermal and pH stabilities than the free GusA enzyme did. Additionally, GusA-CBD showed higher enzymatic activity in the presence of methanol than free GusA did. Evaluation of the protease accessibility of both enzymes revealed that GusA-CBD retained 100% of its activity after 1 h incubation in 0.5 mg/ml protease K, while free GusA completely lost its activity. Simple fusion of CBD as a single domain may be useful for tunable enzyme states to improve enzyme stability in industrial applications. PMID:28099480

Controlled Aggregation and Increased Stability of β-Glucuronidase by Cellulose Binding Domain Fusion.

PubMed

Yeom, Soo-Jin; Han, Gui Hwan; Kim, Moonjung; Kwon, Kil Koang; Fu, Yaoyao; Kim, Haseong; Lee, Hyewon; Lee, Dae-Hee; Jung, Heungchae; Lee, Seung-Goo

2017-01-01

Cellulose-binding domains (CBDs) are protein domains with cellulose-binding activity, and some act as leaders in the localization of cellulosomal scaffoldin proteins to the hydrophobic surface of crystalline cellulose. In this study, we found that a CBD fusion enhanced and improved soluble β-glucuronidase (GusA) enzyme properties through the formation of an artificially oligomeric state. First, a soluble CBD fused to the C-terminus of GusA (GusA-CBD) was obtained and characterized. Interestingly, the soluble GusA-CBD showed maximum activity at higher temperatures (65°C) and more acidic pH values (pH 6.0) than free GusA did (60°C and pH 7.5). Moreover, the GusA-CBD enzyme showed higher thermal and pH stabilities than the free GusA enzyme did. Additionally, GusA-CBD showed higher enzymatic activity in the presence of methanol than free GusA did. Evaluation of the protease accessibility of both enzymes revealed that GusA-CBD retained 100% of its activity after 1 h incubation in 0.5 mg/ml protease K, while free GusA completely lost its activity. Simple fusion of CBD as a single domain may be useful for tunable enzyme states to improve enzyme stability in industrial applications.

Controlled release formulation of an anti-depression drug based on a L-phenylalanate-zinc layered hydroxide intercalation compound

NASA Astrophysics Data System (ADS)

Hashim, Norhayati; Sharif, Sharifah Norain Mohd; Isa, Illyas Md; Hamid, Shahidah Abdul; Hussein, Mohd Zobir; Bakar, Suriani Abu; Mamat, Mazidah

2017-06-01

The intercalation of L-phenylalanate (LP) into the interlayer gallery of zinc layered hydroxide (ZLH) has been successfully executed using a simple direct reaction method. The synthesised intercalation compound, zinc layered hydroxide-L-phenylalanate (ZLH-LP), was characterised using PXRD, FTIR, CHNS, ICP-OES, TGA/DTG, FESEM and TEM. The PXRD patterns of the intercalation compound demonstrate an intense and symmetrical peak, indicating a well-ordered crystalline layered structure. The appearance of an intercalation peak at a low angle of 2θ with a basal spacing of 16.3 Å, signifies the successful intercalation of the L-phenylalanate anion into the interlayer gallery of the host. The intercalation is also validated by FTIR spectroscopy and CHNS elemental analysis. Thermogravimetric analysis confirms that the ZLH-LP intercalation compound has higher thermal stability than the pristine L-phenylalanine. The observed percentage of L-phenylalanate accumulated release varies in each release media, with 84.5%, 79.8%, 63.8% and 61.8% release in phosphate buffer saline (PBS) solution at pH 4.8, deionised water, PBS solution at pH 7.4 and NaCl solution, respectively. The release behaviour of LP from its intercalation compounds in deionised water and PBS solution at pH 4.8 follows pseudo second order, whereas in NaCl solution and PBS solution at pH 7.4, it follows the parabolic diffusion model. This study shows that the synthesised ZLH-LP intercalation compound can be used for the formation of a new generation of materials for targeted drug release with controlled release properties.

In vivo pH monitoring using boron doped diamond microelectrode and silver needles: Application to stomach disorder diagnosis

NASA Astrophysics Data System (ADS)

Fierro, Stéphane; Seishima, Ryo; Nagano, Osamu; Saya, Hideyuki; Einaga, Yasuaki

2013-11-01

This study presents the in vivo electrochemical monitoring of pH using boron doped diamond (BDD) microelectrode and silver needles for potential application in medical diagnosis. Accurate calibration curve for pH determination were obtained through in vitro electrochemical measurements. The increase induced in stomach pH by treatment with pantoprazole was used to demonstrate that it is possible to monitor the pH in vivo using the simple and noninvasive system proposed herein. Using the results of the in vivo and in vitro experiments, a quantitative analysis of the increase in stomach pH is also presented. It is proposed that the catheter-free pH monitoring system presented in this study could be potentially employed in any biological environment.

In vivo pH monitoring using boron doped diamond microelectrode and silver needles: application to stomach disorder diagnosis.

PubMed

Fierro, Stéphane; Seishima, Ryo; Nagano, Osamu; Saya, Hideyuki; Einaga, Yasuaki

2013-11-19

This study presents the in vivo electrochemical monitoring of pH using boron doped diamond (BDD) microelectrode and silver needles for potential application in medical diagnosis. Accurate calibration curve for pH determination were obtained through in vitro electrochemical measurements. The increase induced in stomach pH by treatment with pantoprazole was used to demonstrate that it is possible to monitor the pH in vivo using the simple and noninvasive system proposed herein. Using the results of the in vivo and in vitro experiments, a quantitative analysis of the increase in stomach pH is also presented. It is proposed that the catheter-free pH monitoring system presented in this study could be potentially employed in any biological environment.

Dosage form design and in vitro/in vivo evaluation of cevimeline extended-release tablet formulations.

PubMed

Tajiri, Shinichiro; Kanamaru, Taro; Kamada, Makoto; Makoto, Kamada; Konno, Tsutomu; Nakagami, Hiroaki

2010-01-04

The objective of the present work is to develop an extended-release dosage form of cevimeline. Two types of extended-release tablets (simple matrix tablets and press-coated tablets) were prepared and their potential as extended-release dosage forms were assessed. Simple matrix tablets have a large amount of hydroxypropylcellulose as a rate-controlling polymer and the matrix is homogeneous throughout the tablet. The press-coated tablets consisted of a matrix core tablet, which was completely surrounded by an outer shell containing a large amount of hydroxypropylcellulose. The simple matrix tablets could not sustain the release of cevimeline effectively. In contrast, the press-coated tablets showed a slower dissolution rate compared with simple matrix tablets and the release curve was nearly linear. The dissolution of cevimeline from the press-coated tablets was not markedly affected by the pH of the dissolution medium or by a paddle rotating speed over the range of 50-200 rpm. Furthermore, cevimeline was constantly released from the press-coated tablets in the gastrointestinal tract and the steady-state plasma drug levels were maintained in beagle dogs. These results suggested that the designed PC tablets have a potential for extended-release dosage forms.

Average rainwater pH, concepts of atmospheric acidity, and buffering in open systems

NASA Astrophysics Data System (ADS)

Liljestrand, Howard M.

The system of water equilibrated with a constant partial pressure of CO 2, as a reference point for pH acidity-alkalinity relationships, has nonvolatile acidity and alkalinity components as conservative quantities, but not [H +]. Simple algorithms are presented for the determination of the average pH for combinations of samples both above and below pH 5.6. Averaging the nonconservative quantity [H +] yields erroneously low mean pH values. To extend the open CO 2 system to include other volatile atmospheric acids and bases distributed among the gas, liquid and particulate matter phases, a theoretical framework for atmospheric acidity is presented. Within certain oxidation-reduction limitations, the total atmospheric acidity (but not free acidity) is a conservative quantity. The concept of atmospheric acidity is applied to air-water systems approximating aerosols, fogwater, cloudwater and rainwater. The buffer intensity in hydrometeors is described as a function of net strong acidity, partial pressures of acid and base gases and the water to air ratio. For high liquid to air volume ratios, the equilibrium partial pressures of trace acid and base gases are set by the pH or net acidity controlled by the nonvolatile acid and base concentrations. For low water to air volume ratios as well as stationary state systems such as precipitation scavenging with continuous emissions, the partial pressures of trace gases (NH 3, HCl, HNO 3, SO 2 and CH 3COOH) appear to be of greater or equal importance as carbonate species as buffers in the aqueous phase.

Development of the Glass Electrode and the pH Response

ERIC Educational Resources Information Center

Graham, Daniel J.; Jaselskis, Bruno; Moore, Carl E.

2013-01-01

The glass electrode is the most commonly used device to access the pH of an aqueous solution. It attains highly accurate measurements via simple and well-established procedures. However, the reasons why the glass electrode potential scales with hydrogen ion concentration according to almost Nernstian potential values have been long-standing…

Macroion induced dehydration of weak polyelectrolyte brushes

NASA Astrophysics Data System (ADS)

Zheng, Zhongli; Zhu, Y. Elaine

2014-03-01

The interaction of macroions, including polyelectrolytes, DNAs, and proteins, with polymer and cellular surfaces is critically related to many biomolecular activities, such as protein adsorption and DNA hybridization at probe surfaces. In an experimental approach to examine the macroion electrostatic interaction with a polymer surface while minimizing the long-debated hydrophobic interaction, we study the interaction of molybdenum-based inorganic polyoxometalate (POM) nanoclusters carrying 42 negative charges as model hydrophilic macroions with surface-tethered poly-2-vinylpyridine (P2VP) brushes immersed in aqueous solutions. By AFM, QCM, and contact goniometer, we have observed the collapse of P2VP chains by adding POM macroions at a constant pH. Surprisingly, added POM macroions can cause the shift of swollen-to-collapse transition pH to a lower value, in contrast to the shift to high pH value by adding simple monovalent salts. At sufficiently high POM concentration, a stable POM-P2VP composite layer, showing little dependence on solution pH and additional salts, can be formed, suggesting a simple route to construct meso-porous polymer membranes.

How-to-Do-It: A Simple Demonstration of Fermentation.

ERIC Educational Resources Information Center

Yurkiewicz, William J.; And Others

1989-01-01

Described is a simple demonstration of fermentation. The materials needed, the basic experimental set-up, and various projects are outlined. Included are a diagram of an apparatus for measuring carbon dioxide production and a table showing typical results of the effect of pH on fermentation. (RT)

pH : a key control of the nature and distribution of dissolved organic matter and associated trace metals in soil

NASA Astrophysics Data System (ADS)

Pédrot, M.; Dia, A.; Davranche, M.

2009-04-01

Dissolved organic matter is ubiquitous at the Earth's surface and plays a prominent role in controlling metal speciation and mobility from soils to hydrosystems. Humic substances (HS) are usually considered to be the most reactive fraction of organic matter. Humic substances are relatively small and formed by chemically diverse organic molecules, bearing different functional groups that act as binding sites for cations and mineral surfaces. Among the different environmental physicochemical parameters controlling the metal speciation, pH is likely to be the most important one. Indeed, pH affect the dissociation of functional groups, and thus can influence the HS structure, their ability to complex metals, their solubility degree allowing the formation of aggregates at the mineral surface. In this context, soil/water interactions conducted through batch system experiments, were carried out with a wetland organic-rich soil to investigate the effect of pH on the release of dissolved organic carbon (DOC) and associated trace elements. The pH was regulated between 4 and 7.5 using an automatic pH stat titrator. Ultrafiltration experiments were performed to separate the dissolved organic pool following decreasing pore sizes (30 kDa, 5 kDa and 2 kDa with 1 Da = 1 g.mol-1). The pH increase induced a significant DOC release, especially in heavy organic molecules (size >5 kDa) with a high aromaticity (>30 %). These were probably humic acids (HA). This HA release influenced (i) directly the trace element concentrations in soil solution since HA were enriched in several trace elements such as Th, REE, Y, U, Cr and Cu; and (ii) indirectly by the breaking of clay-humic complexes releasing Fe- and Al-rich nanoparticles associated with V, Pb and Ti. By contrast, at acid pH, most HS were complexed onto mineral surfaces. They also sequestered iron nanoparticles. Therefore, at low pH, most part of DOC molecules had a size < 5 kDa and lower aromaticity. Thus, the DOC was mostly composed of simple organic compounds little complexing. Consequently, the soil solution was depleted in trace elements such as Th, REE, Y, U, Cr, Cu, Al, Fe, V, Pb and Ti, but also enriched in Ca, Sr, Ba, Mn, Mg, Co, Zn and in a lesser proportion in Rb, Li and Ni. The aromaticity in the fractions <5 kDa was higher than in the fractions <30 kDa or <0.2 µm. Complementary experiments were performed to understand the HS size distribution and aromaticity according to pH and ionic strength .The molecular size and shape of HS is usually explained by two concepts: (i) the macropolymeric structure with heavy organic molecules considered to be flexible linear polyelectrolytes and (ii) the supramolecular structure with an association of a complex mixture of different molecules held together by dispersive weak forces. Ours results supported the HA supramolecular structure at neutral or basic pH conditions. But, at acid pH, a disruption of the humic supramolecular associations involved the release of small organic molecules with a high aromaticity. Moreover, this aromaticity variation can be due also to the presence of fulvic acids in the fractions <5 kDa and a mixture of heavy organic molecules little complexing in the fractions >5 kDa. These latter molecules displayed a low aromaticity decreasing the global aromaticity of the fractions <30 kDa and <0.2 µm. To summarize, these new data demonstrated that the DOC and trace element concentrations of the soil solutions were strongly controlled by pH. This parameter influenced the nature and the size of the DOC as well as, the trace element concentrations in the soil solutions, with a decreasing contribution of HA when pH decreased. This pH dependence is a key issue of concern since local (human pressure) and/or global (climatic) warning result in pH water changes.

Fabrication of graphene oxide-modified chitosan for controlled release of dexamethasone phosphate

NASA Astrophysics Data System (ADS)

Sun, Huanghui; Zhang, Lingfan; Xia, Wei; Chen, Linxiao; Xu, Zhizhen; Zhang, Wenqing

2016-07-01

Functionalized graphene oxide with its unique physical and chemical properties is widely applied in biomaterials, especially in drug carrier materials. In the past few years, a number of different drugs have been loaded on functionalized graphene oxide via π-π stacking and hydrophobic interactions. The present report described a new approach, dexamethasone phosphate successfully loaded onto graphene oxide-chitosan nanocomposites as drug carrier materials by covalent bonding of phosphate ester linkage. Compared with the graphene oxide-chitosan nanocomposites that dexamethasone phosphate was loaded on via simple physical attachment, covalently linked composites as drug carrier materials were more biocompatible which effectively reduced the burst release of drug, and controlled the release of drug in different pH conditions.

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.

The Angelchik prosthesis for gastro-oesophageal reflux: symptomatic and objective assessment.

PubMed Central

Weaver, R. M.; Temple, J. G.

1985-01-01

Twenty-three patients with intractable gastro-oesophageal reflux were treated by insertion of the Angelchik antireflux prosthesis. Good symptomatic relief was achieved in over 80% of patients reviewed up to 28 months after operation and there was marked resolution of oesophagitis as seen on endoscopy. Oesophageal manometry and pH studies performed preoperatively and at 3 and 12 months after operation, showed a significant increase in lower oesophageal sphincter pressure with decreased acid reflux. Some technical problems were encountered, but the prosthesis is potentially a simple and effective means of controlling gastro-oesophageal reflux. Images Fig. 1 PMID:4051424

A facile and efficient method to modify gold nanorods with thiolated DNA at a low pH value.

PubMed

Shi, Dangwei; Song, Chen; Jiang, Qiao; Wang, Zhen-Gang; Ding, Baoquan

2013-03-28

We report a simple, rapid and efficient strategy for modification of gold nanorods (AuNRs) with thiolated DNA at low solution pH and high salt concentration. DNA functionalized AuNRs were then used to assemble with DNA modified gold nanoparticles to form discrete satellite nanostructures.

Microfluidic droplet trapping array as nanoliter reactors for gas-liquid chemical reaction.

PubMed

Zhang, Qingquan; Zeng, Shaojiang; Qin, Jianhua; Lin, Bingcheng

2009-09-01

This article presents a simple method for trapping arrays of droplets relying on the designed microstructures of the microfluidic device, and this has been successfully used for parallel gas-liquid chemical reaction. In this approach, the trapping structure is composed of main channel, lateral channel and trapping region. Under a negative pressure, array droplets can be generated and trapped in the microstructure simultaneously, without the use of surfactant and the precise control of the flow velocity. By using a multi-layer microdevice containing the microstructures, single (pH gradient) and multiple gas-liquid reactions (metal ion-NH3 complex reaction) can be performed in array droplets through the transmembrane diffusion of the gas. The droplets with quantitative concentration gradient can be formed by only replacing the specific membrane. The established method is simple, robust and easy to operate, demonstrating the potential of this device for droplet-based high-throughput screening.

Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

2013-02-01

The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

A novel solubility-modulated granules through porosity osmotic pump for controlled carvedilol delivery.

PubMed

Song, Qun-Li; Li, Ping; Li, Yu-Min

2012-01-01

A method for the preparation of porosity osmotic pump granules was obtained by modulating carvedilol solubility with tartaric acid. Controlled porosity of the membrane was accomplished by the use of pore-forming agent in the coating. In this study, carvedilol was chosen as a model drug with an aim to develop a zero-order release system; tartaric acid was used as the solubility promoter; NaCl was used as the osmotic agent; cellulose acetate (CA) was used as the materials of semipermeable membrane; and PEG-400 was used as the pore-forming agent in the semipermeable membrane. The influence of different factors or levels on the in vitro release was studied. In order to simulate the gastrointestinal tract environments, two kinds of pH media (pH 1.5 and 6.8) on drug release were studied in this research, respectively. This porosity osmotic pump was optimized by single factor design experiments, and it was found to deliver carvedilol at a zero-order rate within 12 h and controlled release for 24 h. We drew a conclusion that the solubility-modulated porosity osmotic pump system is simple to prepare and might be used for the preparation of osmotic pump system of other poorly water-soluble drugs with alkaline or acid groups.

Tyrosine assisted size controlled synthesis of silver nanoparticles and their catalytic, in-vitro cytotoxicity evaluation.

PubMed

Maddinedi, Sireesh Babu; Mandal, Badal Kumar; Anna, Kiran Kumar

2017-04-01

A simple, green approach for the size controllable preparation of silver nanoparticles (SNPs) using tyrosine as reducing and capping agent is shown here. The size of SNPs is controlled by varying the pH of tyrosine solution. The as synthesized SNPs are characterized by using XRD, UV-Visible, DLS, TEM and SAED. Zeta potential measurements revealed the stability of tyrosine capped silver nanocolloids. Furthermore, catalytic activity studies concluded that the smaller SNPs acts as good catalyst and the catalytic activity depends on size of the nanoparticles. Further, the in-vitro cytotoxicity experiments concluded that the cytotoxicity of the prepared SNPs towards mouse fibroblast (3T3) cell lines is size and dose dependent. Additionally, the present approach is substitute to the traditional methods that are being used now-a-days for size controlled synthesis of SNPs. Copyright © 2017 Elsevier B.V. All rights reserved.

Proton Transport and pH Control in Fungi.

PubMed

Kane, Patricia M

2016-01-01

Despite diverse and changing extracellular environments, fungi maintain a relatively constant cytosolic pH and numerous organelles of distinct lumenal pH. Key players in fungal pH control are V-ATPases and the P-type proton pump Pma1. These two proton pumps act in concert with a large array of other transporters and are highly regulated. The activities of Pma1 and the V-ATPase are coordinated under some conditions, suggesting that pH in the cytosol and organelles is not controlled independently. Genomic studies, particularly in the highly tractable S. cerevisiae, are beginning to provide a systems-level view of pH control, including transcriptional responses to acid or alkaline ambient pH and definition of the full set of regulators required to maintain pH homeostasis. Genetically encoded pH sensors have provided new insights into localized mechanisms of pH control, as well as highlighting the dynamic nature of pH responses to the extracellular environment. Recent studies indicate that cellular pH plays a genuine signaling role that connects nutrient availability and growth rate through a number of mechanisms. Many of the pH control mechanisms found in S. cerevisiae are shared with other fungi, with adaptations for their individual physiological contexts. Fungi deploy certain proton transport and pH control mechanisms not shared with other eukaryotes; these regulators of cellular pH are potential antifungal targets. This review describes current and emerging knowledge proton transport and pH control mechanisms in S. cerevisiae and briefly discusses how these mechanisms vary among fungi.

Proton Transport and pH Control in Fungi

PubMed Central

Kane, Patricia M.

2018-01-01

Despite diverse and changing extracellular environments, fungi maintain a relatively constant cytosolic pH and numerous organelles of distinct lumenal pH. Key players in fungal pH control are V-ATPases and the P-type proton pump Pma1. These two proton pumps act in concert with a large array of other transporters and are highly regulated. The activities of Pma1 and the V-ATPaseare coordinated under some conditions, suggesting that pH in the cytosol and organelles is not controlled independently. Genomic studies, particularly in the highly tractable S. cerevisiae, are beginning to provide a systems-level view of pH control, including transcriptional responses to acid or alkaline ambient pH and definition of the full set of regulators required to maintain pH homeostasis. Genetically encoded pH sensors have provided new insights into localized mechanisms of pH control, as well as highlighting the dynamic nature of pH responses to the extracellular environment. Recent studies indicate that cellular pH plays a genuine signaling role that connects nutrient availability and growth rate through a number of mechanisms. Many of the pH control mechanisms found in S. cerevisiae are shared with other fungi, with adaptations for their individual physiological contexts. Fungi deploy certain proton transport and pH control mechanisms not shared with other eukaryotes; these regulators of cellular pH are potential antifungal targets. This re view describes current and emerging knowledge proton transport and pH control mechanisms in S. cerevisiae and briefly discusses how these mechanisms vary among fungi. PMID:26721270

Relationship between gastroesophageal reflux disease and Ph nose and salivary: proposal of a simple method outpatient in patients adults.

PubMed

Caruso, Arturo Armone; Del Prete, Salvatore; Ferrara, Lydia; Serra, Raffaele; Telesca, Donato Alessandro; Ruggiero, Simona; Russo, Teresa; Sivero, Luigi

2016-01-01

The frequency of gastroesophageal reflux disease (GERD) is increasing, in part through easy inspection of the upper digestive tract, but especially for a real spread of the disease as a consequence of modernity, lifestyle, incorrect dietary rules, and stress arising from social norms. It is a common chronic gastrointestinal disorder in Europe and the United States. The aim of our study is to highlight a relationship between gastroesophageal reflux disease and salivary pH as evidenced by indicator strips, especially in the outpatient field. Twenty adult subjects (10 males and 10 females) aged between 18 and 50 years (GROUP A)_ were selected. How to control a homogeneous group of 20 patients without GERD, or from any type of allergies (GROUP B) was enlisted. This method has provided excellent results showing no difference in the measured values compared with the traditional instrumental measurement. Our study has allowed us to observe a strong correlation between the saliva pH, nasal cavities and the interaction between the two districts, and could be the basis for a diagnosis of GERD especially in primary health care clinics and in the initial stage of the disease.

BSA adsorption onto nanospheres: Influence of surface curvature as probed by electrophoretic light scattering and UV/vis spectroscopy

NASA Astrophysics Data System (ADS)

Sánchez-Pérez, Julio A.; Gallardo-Moreno, Amparo M.; González-Martín, M. Luisa; Vadillo-Rodríguez, Virginia

2015-10-01

The influence of surface curvature on the adsorption of bovine serum albumin (BSA) was evaluated through the combination of two fairly simple techniques: electrophoretic light scattering and UV/vis spectroscopy. Measurements were carried out for a range of protein concentrations (0-320 μg/ml) at pH 3.5, 4.5 and 7 using hydrophobic polystyrene nanospheres of 38.8, 82 and 220 nm in diameter. The results obtained demonstrate that the charge of the BSA molecules in solution dictates the pH-dependent behavior of the protein-coated nanospheres, indicating in all cases a significant adsorption of BSA molecules. At a fixed pH, however, it is the zeta potential that characterizes the uncoated nanospheres normalized by their surface area that primarily controls protein adsorption. In particular, it is found that the rate at which BSA interact with the different nanospheres increases as their negative zeta potential per unit area (or diameter) increases (decreases) regardless of the pH. Moreover, provided that adsorption occurs away from the isoelectric point of the protein, highly curved surfaces are found to stabilize the native-like conformation of BSA upon adsorption by likely reducing lateral interactions between adsorbed molecules.

Student understanding of pH: "i don't know what the log actually is, i only know where the button is on my calculator".

PubMed

Watters, Dianne J; Watters, James J

2006-07-01

In foundation biochemistry and biological chemistry courses, a major problem area that has been identified is students' lack of understanding of pH, acids, bases, and buffers and their inability to apply their knowledge in solving acid/base problems. The aim of this study was to explore students' conceptions of pH and their ability to solve problems associated with the behavior of biological acids to understand the source of student difficulties. The responses given by most students are characteristic of an atomistic approach in which they pay no attention to the structure of the problem and concentrate only on juggling the elements together until they get a solution. Many students reported difficulty in understanding what the question was asking and were unable to interpret a simple graph showing the pH activity profile of an enzyme. The most startling finding was the lack of basic understanding of logarithms and the inability of all except one student to perform a simple calculation on logs without a calculator. This deficiency in high school mathematical skills severely hampered their understanding of pH. This study has highlighted a widespread deficiency in basic mathematical skills among first year undergraduates and a fragmented understanding of acids and bases. Implications for the way in which the concepts of pH and buffers are taught are discussed. Copyright © 2006 International Union of Biochemistry and Molecular Biology, Inc.

Highly efficient treatment of aerobic vaginitis with simple acidic buffered gels: The importance of pH and buffers on the microenvironment of vaginas.

PubMed

Sun, Xiaodong; Qiu, Haiying; Jin, Yiguang

2017-06-15

Aerobic vaginitis (AV) leads to uterus deep infection or preterm birth. Antibacterial agents are not optimal therapeutics of AV. Here, we report a series of temperature-sensitive in situ forming acidic buffered gels for topical treatment of AV, involving lactate, acetate, and citrate gels at pH 3.5, 5.0, and 6.5. AV rat models were prepared following vaginal infection with Staphylococcus aureus and Escherichia coli. In vitro/in vivo studies of the buffered gels were performed compared with ofloxacin gels and blank gels. All the buffered gels showed the lower in vitro antibacterial activities than ofloxacin gels but the better in vivo anti-S. aureus effects and similar anti-E. coli effects. The buffered gels improved Lactobacillus growth in the vaginas. Both the healthy rat vaginal pH and the pH of rat vaginas treated with the buffered gels were about 6.5 though the AV rat models or ones treated with ofloxacin gels still remained at the high pH more than 7.0. After treatments with the buffered gels, the vaginal smears changed to a clean state nearly without aerobic bacteria, the vaginal tissues were refreshed, and the immunoreactions were downregulated. The acidic buffered gels bring rapid decrease of local vaginal pH, high antibacterial activities, improvement of probiotics, and alleviation of inflammation. They are simple, highly efficient, and safe anti-AV formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamic bioprocessing and microfluidic transport control with smart magnetic nanoparticles in laminar-flow devices

PubMed Central

Lai, James J.; Nelson, Kjell; Nash, Michael A.; Hoffman, Allan S.; Yager, Paul; Stayton, Patrick S.

2010-01-01

In the absence of applied forces, the transport of molecules and particulate reagents across laminar flowstreams in microfluidic devices is dominated by the diffusivities of the transported species. While the differential diffusional properties between smaller and larger diagnostic targets and reagents have been exploited for bioseparation and assay applications, there are limitations to methods that depend on these intrinsic size differences. Here a new strategy is described for exploiting the sharply reversible change in size and magnetophoretic mobility of “smart” magnetic nanoparticles (mNPs) to perform bioseparation and target isolation under continuous flow processing conditions. The isolated 5 nm mNPs do not exhibit significant magnetophoretic velocities, but do exhibit high magnetophoretic velocities when aggregated by the action of a pH-responsive polymer coating. A simple external magnet is used to magnetophorese the aggregated mNPs that have captured a diagnostic target from a lower pH laminar flowstream (pH 7.3) to a second higher pH flowstream (pH 8.4) that induces rapid mNP dis-aggregation. In this second disaggregated state and flowstream, the mNPs continue to flow past the magnet rather than being immobilized at the channel surface near the magnet. This stimuli-responsive reagent system has been shown to transfer 81% of a model protein target from an input flowstream to a second flowstream in a continuous flow H-filter device. PMID:19568666

Dynamic bioprocessing and microfluidic transport control with smart magnetic nanoparticles in laminar-flow devices.

PubMed

Lai, James J; Nelson, Kjell E; Nash, Michael A; Hoffman, Allan S; Yager, Paul; Stayton, Patrick S

2009-07-21

In the absence of applied forces, the transport of molecules and particulate reagents across laminar flowstreams in microfluidic devices is dominated by the diffusivities of the transported species. While the differential diffusional properties between smaller and larger diagnostic targets and reagents have been exploited for bioseparation and assay applications, there are limitations to methods that depend on these intrinsic size differences. Here a new strategy is described for exploiting the sharply reversible change in size and magnetophoretic mobility of "smart" magnetic nanoparticles (mNPs) to perform bioseparation and target isolation under continuous flow processing conditions. The isolated 5 nm mNPs do not exhibit significant magnetophoretic velocities, but do exhibit high magnetophoretic velocities when aggregated by the action of a pH-responsive polymer coating. A simple external magnet is used to magnetophorese the aggregated mNPs that have captured a diagnostic target from a lower pH laminar flowstream (pH 7.3) to a second higher pH flowstream (pH 8.4) that induces rapid mNP disaggregation. In this second dis-aggregated state and flowstream, the mNPs continue to flow past the magnet rather than being immobilized at the channel surface near the magnet. This stimuli-responsive reagent system has been shown to transfer 81% of a model protein target from an input flowstream to a second flowstream in a continuous flow H-filter device.

Adjustment of ionized calcium concentration for serum pH is not a valid marker of calcium homeostasis: implications for identifying individuals at risk of calcium metabolic disorders.

PubMed

Lam, Virginie; Dhaliwal, Satvinder S; Mamo, John C

2013-05-01

Ionized calcium (iCa) is the biologically active form of this micronutrient. Serum determination of iCa is measured via ion-electrode potentiometry (IEP) and reporting iCa relative to pH 7.4 is normally utilized to avoid the potential confounding effects of ex vivo changes to serum pH. Adjustment of iCa for pH has not been adequately justified. In this study, utilizing carefully standardized protocols for blood collection, the preparation of serum and controlling time of collection-to-analysis, we determined serum iCa and pH utilizing an IEP-analyser hosted at an accredited diagnostic laboratory. Regression analysis of unadjusted-iCa (iCa(raw)) concentration versus pH was described by linear regression and accounted for 37% of serum iCa(raw) variability. iCa(raw) was then expressed at pH 7.4 by either adjusting iCa(raw) based on the linear regression equation describing the association of iCa with serum pH (iCa(regr)) or using IEP coded published normative equations (iCa(pub)). iCa(regr) was comparable to iCa(raw), indicating that blood collection and processing methodologies were sound. However, iCa(pub) yielded values that were significantly lower than iCa(raw). iCa(pub) did not identify 15% subjects who had greater than desirable serum concentration of iCa based on iCa(raw). Sixty percent of subjects with low levels of iCa(raw) were also not detected by iCa(pub). Determination of the kappa value measure of agreement for iCa(raw) versus iCa(pub) showed relatively poor concordance (κ = 0.42). With simple protocols that avoid sampling artefacts, expressing iCa(raw) is likely to be a more valid and physiologically relevant marker of calcium homeostasis than is iCa(pub).

A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy

PubMed Central

Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

2016-01-01

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion. PMID:27025266

A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy.

PubMed

Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

2016-03-30

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion.

Homeopathic potentization based on nanoscale domains.

PubMed

Czerlinski, George; Ypma, Tjalling

2011-12-01

The objectives of this study were to present a simple descriptive and quantitative model of how high potencies in homeopathy arise. The model begins with the mechanochemical production of hydrogen and hydroxyl radicals from water and the electronic stabilization of the resulting nanodomains of water molecules. The life of these domains is initially limited to a few days, but may extend to years when the electromagnetic characteristic of a homeopathic agent is copied onto the domains. This information is transferred between the original agent and the nanodomains, and also between previously imprinted nanodomains and new ones. The differential equations previously used to describe these processes are replaced here by exponential expressions, corresponding to simplified model mechanisms. Magnetic stabilization is also involved, since these long-lived domains apparently require the presence of the geomagnetic field. Our model incorporates this factor in the formation of the long-lived compound. Numerical simulation and graphs show that the potentization mechanism can be described quantitatively by a very simplified mechanism. The omitted factors affect only the fine structure of the kinetics. Measurements of pH changes upon absorption of different electromagnetic frequencies indicate that about 400 nanodomains polymerize to form one cooperating unit. Singlet excited states of some compounds lead to dramatic changes in their hydrogen ion dissociation constant, explaining this pH effect and suggesting that homeopathic information is imprinted as higher singlet excited states. A simple description is provided of the process of potentization in homeopathic dilutions. With the exception of minor details, this simple model replicates the results previously obtained from a more complex model. While excited states are short lived in isolated molecules, they become long lived in nanodomains that form coherent cooperative aggregates controlled by the geomagnetic field. These domains either slowly emit biophotons or perform specific biochemical work at their target.

High temperature hydrothermal vent fluids in Yellowstone Lake: Observations and insights from in-situ pH and redox measurements

NASA Astrophysics Data System (ADS)

Tan, Chunyang; Cino, Christie D.; Ding, Kang; Seyfried, William E.

2017-09-01

ROV investigation of hydrothermal fluids issuing from vents on the floor of Yellowstone lake revealed temperatures in excess of 170 °C - the highest temperature yet reported for vent fluids within Yellowstone National Park (YNP). The study site is east of Stevenson Island at depth of approximately 100-125 m. In-situ pH and redox measurements of vent fluids were made using solid state sensors designed to sustain the elevated temperatures and pressures. YSZ membrane electrode with Ag/Ag2O internal element and internal pressure balanced Ag/AgCl reference electrode were used to measure pH, while a platinum electrode provided redox constraints. Lab verification of the pH sensor confirmed excellent agreement with Nernst law predictions, especially at temperatures in excess of 120 °C. In-situ pH values of between 4.2 and 4.5 were measured for the vent fluids at temperatures of 120 to 150 °C. The slightly acidic vent fluids are likely caused by CO2 enrichment in association with magmatic degassing effects that occur throughout YNP. This is consistent with results of simple model calculations and direct observation of CO2 bubbles in the immediate vicinity of the lake floor vents. Simultaneous redox measurements indicated moderate to highly reducing conditions (- 0.2 to - 0.3 V). As typical of measurements of this kind, internal and external redox disequilibria likely preclude unambiguous determination of redox controlling reactions. Redox disequilibria, however, can be expected to drive microbial metabolism and diversity in the near vent environment. Thus, the combination of in-situ pH and redox sensor deployments may ultimately provide the requisite framework to better understand the microbiology of the newly discovered hot vents on Yellowstone lake floor.

Kinetics of steel slag leaching: Batch tests and modeling

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

De Windt, Laurent, E-mail: laurent.dewindt@mines-paristech.fr; Chaurand, Perrine; Rose, Jerome

2011-02-15

Reusing steel slag as an aggregate for road construction requires to characterize the leaching kinetics and metal releases. In this study, basic oxygen furnace (BOF) steel slag were subjected to batch leaching tests at liquid to solid ratios (L/S) of 10 and 100 over 30 days; the leachate chemistry being regularly sampled in time. A geochemical model of the steel slag is developed and validated from experimental data, particularly the evolution with leaching of mineralogical composition of the slag and trace element speciation. Kinetics is necessary for modeling the primary phase leaching, whereas a simple thermodynamic equilibrium approach can bemore » used for secondary phase precipitation. The proposed model simulates the kinetically-controlled dissolution (hydrolysis) of primary phases, the precipitation of secondary phases (C-S-H, hydroxide and spinel), the pH and redox conditions, and the progressive release of major elements as well as the metals Cr and V. Modeling indicates that the dilution effect of the L/S ratio is often coupled to solubility-controlled processes, which are sensitive to both the pH and the redox potential. A sensitivity analysis of kinetic uncertainties on the modeling of element releases is performed.« less

A green and facile approach for synthesizing imine to develop optical biosensor for wide range detection of bilirubin in human biofluids.

PubMed

Ellairaja, Sundaram; Shenbagavalli, Kathiravan; Ponmariappan, Sarkaraisamy; Vasantha, Vairathevar Sivasamy

2017-05-15

Bilirubin, a key biomarker for the jaundice and its clinical diagnosis needs a better analytical tool. A novel and simple fluorescent platform based on (2,2'-((1E,1'E)-((6-bromopyridine-2,3-diyl) bis(azanylylidene)) bis(methanylylidene diphenol) (BAMD) was designed. BAMD showed a remarkable fluorescent intensity with a very good quantum yield of 0.85 and lifetime of 870ps. Hence, it was applied for the determination of bilirubin using both colorimetric and fluorimetric techniques in physiological and basic pH. Under optimized experimental conditions, the probe detects bilirubin selectively in the presence of other interfering biomolecules and metal ions. The linear range of detection is 1pM-500µM at pH=7.4 and LOD is 2.8 and 3.3 pM at pH=7.4 and 9.0, respectively, which were reported so far. The probe detects the bilirubin through FRET mechanism. The practical application of the probe was successfully tested in the human blood and urine samples. Based on all above advantages, this simple idea can be applied to design a simple clinical diagnostic tool for jaundice. Copyright © 2016. Published by Elsevier B.V.

A pH Sensor Based on a Stainless Steel Electrode Electrodeposited with Iridium Oxide

ERIC Educational Resources Information Center

Martinez, C. C. M.; Madrid, R. E.; Felice, C. J.

2009-01-01

A simple procedure to make an iridium oxide (IrO[subscript 2]) electrodeposited pH sensor, that can be used in a chemical, biomedical, or materials laboratory, is presented here. Some exercises, based on this sensor, that can be used to teach important concepts in the field of biomedical, biochemical, tissue, or materials engineering, are also…

Answer This Simple Question

ERIC Educational Resources Information Center

Smith, J. Elspeth S.

2011-01-01

In this essay, the author discusses her journey from her first year of the PhD program at USC, and the work she is doing now for a company that builds infrastructure in Afghanistan. She explores the ways in which studies for her 1985 PhD in Rhetoric, Linguistics and Literature did and did not prepare her for the work she does now. Her memoir…

A visual assay and spectrophotometric determination of LLM-105 explosive using detection of gold nanoparticle aggregation at two pH values.

PubMed

He, Yi; Cheng, Yang

2016-08-01

We report a simple, rapid, and sensitive assay for visual and spectrophotometric detection of the 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) explosive. The assay is based on different interactions between LLM-105 and gold nanoparticle (AuNP) dispersions at two pH values, leading to the formation of dispersed or aggregated AuNPs. Two AuNP dispersions at two pH values were applied to recognize and detect LLM-105 instead of traditional AuNP dispersion under an aptotic pH to improve the anti-interference ability. The developed assay showed excellent sensitivity with a detection limit of 3 ng/mL, and the presence of as low as 0.2 μg/mL LLM-105 can be directly detected with the bare eye. This sensitivity is about six orders of magnitude higher than that of the reported traditional assays. Additionally, the assay exhibited good selectivity toward LLM-105 over other explosives, sulfur-containing compounds, and amines. Graphical abstract A simple, sensitive, and selective assay for LLM-105 was developed based on the pH-dependent interaction between the LLM-105 explosive and gold nanoparticle dispersion.

Origin of the pressure-dependent Tc valley in superconducting simple cubic phosphorus

NASA Astrophysics Data System (ADS)

Wu, Xianxin; Jeschke, Harald O.; Di Sante, Domenico; von Rohr, Fabian O.; Cava, Robert J.; Thomale, Ronny

2018-03-01

Motivated by recent experiments, we investigate the pressure-dependent electronic structure and electron-phonon (e-ph) coupling for simple cubic phosphorus by performing first-principles calculations within the full potential linearized augmented plane-wave method. As a function of increasing pressure, our calculations show a valley feature in Tc, followed by an eventual decrease for higher pressures. We demonstrate that this Tc valley at low pressures is due to two nearby Lifshitz transitions, as we analyze the band-resolved contributions to the e-ph coupling. Below the first Lifshitz transition, the phonon hardening and shrinking of the γ Fermi surface with s -orbital character results in a decreased Tc with increasing pressure. After the second Lifshitz transition, the appearance of δ Fermi surfaces with 3 d -orbital character generate strong e-ph interband couplings in α δ and β δ channels, and hence lead to an increase of Tc. For higher pressures, the phonon hardening finally dominates, and Tc decreases again. Our study reveals that the intriguing Tc valley discovered in experiment can be attributed to Lifshitz transitions, while the plateau of Tc detected at intermediate pressures appears to be beyond the scope of our analysis. This strongly suggests that aside from e-ph coupling, electronic correlations along with plasmonic contributions may be relevant for simple cubic phosphorus. Our findings hint at the notion that increasing pressure can shift the low-energy orbital weight towards d character, and as such even trigger an enhanced importance of orbital-selective electronic correlations despite an increase of the overall bandwidth.

Simple and sensitive HPLC method with fluorescence detection for the measurement of ibuprofen in rat plasma: application to a long-lasting dosage form.

PubMed

Hassan, Ahmed Sheikh; Sapin, Anne; Ubrich, Nathalie; Maincent, Philippe; Bolzan, Claire; Leroy, Pierre

2008-10-01

A simple and sensitive high-performance liquid chromatography (HPLC) assay applied to the measurement of ibuprofen in rat plasma has been developed. Two parameters have been investigated to improve ibuprofen detectability using fluorescence detection: variation of mobile phase pH and the use of beta-cyclodextrin (beta-CD). Increasing the pH value from 2.5 to 6.5 and adding 5 mM beta-CD enhanced the fluorescence signal (lambda(exc) = 224 nm; lambda(em) = 290 nm) by 2.5 and 1.3-fold, respectively, when using standards. In the case of plasma samples, only pH variation significantly lowered detection and quantification limits, down to 10 and 35 ng/mL, respectively. Full selectivity was obtained with a single step for plasma treatment, that is, protein precipitation with acidified acetonitrile. The validated method was applied to a pharmacokinetic study of ibuprofen encapsulated in microspheres and subcutaneously administered to rats.

Removal of phosphate from greenhouse wastewater using hydrated lime.

PubMed

Dunets, C Siobhan; Zheng, Youbin

2014-01-01

Phosphate (P) contamination in nutrient-laden wastewater is currently a major topic of discussion in the North American greenhouse industry. Precipitation of P as calcium phosphate minerals using hydrated lime could provide a simple, inexpensive method for retrieval. A combination of batch experiments and chemical equilibrium modelling was used to confirm the viability of this P removal method and determine lime addition rates and pH requirements for greenhouse wastewater of varying nutrient compositions. Lime: P ratio (molar ratio of CaMg(OH)₄: PO₄‒P) provided a consistent parameter for estimating lime addition requirements regardless of initial P concentration, with a ratio of 1.5 providing around 99% removal of dissolved P. Optimal P removal occurred when lime addition increased the pH from 8.6 to 9.0, suggesting that pH monitoring during the P removal process could provide a simple method for ensuring consistent adherence to P removal standards. A Visual MINTEQ model, validated using experimental data, provided a means of predicting lime addition and pH requirements as influenced by changes in other parameters of the lime-wastewater system (e.g. calcium concentration, temperature, and initial wastewater pH). Hydrated lime addition did not contribute to the removal of macronutrient elements such as nitrate and ammonium, but did decrease the concentration of some micronutrients. This study provides basic guidance for greenhouse operators to use hydrated lime for phosphate removal from greenhouse wastewater.

RuO2 pH Sensor with Super-Glue-Inspired Reference Electrode

PubMed Central

Wajrak, Magdalena; Alameh, Kamal

2017-01-01

A pH-sensitive RuO2 electrode coated in a commercial cyanoacrylate adhesive typically exhibits very low pH sensitivity, and could be paired with a RuO2 working electrode as a differential type pH sensor. However, such sensors display poor performance in real sample matrices. A pH sensor employing a RuO2 pH-sensitive working electrode and a SiO2-PVB junction-modified RuO2 reference electrode is developed as an alternative high-performance solution. This sensor exhibits a performance similar to that of a commercial glass pH sensor in some common sample matrices, particularly, an excellent pH sensitivity of 55.7 mV/pH, a hysteresis as low as 2.7 mV, and a drift below 2.2 mV/h. The developed sensor structure opens the way towards the development of a simple, cost effective, and robust pH sensor for pH analysis in various sample matrices. PMID:28878182

RuO₂ pH Sensor with Super-Glue-Inspired Reference Electrode.

PubMed

Lonsdale, Wade; Wajrak, Magdalena; Alameh, Kamal

2017-09-06

A pH-sensitive RuO₂ electrode coated in a commercial cyanoacrylate adhesive typically exhibits very low pH sensitivity, and could be paired with a RuO₂ working electrode as a differential type pH sensor. However, such sensors display poor performance in real sample matrices. A pH sensor employing a RuO₂ pH-sensitive working electrode and a SiO₂-PVB junction-modified RuO₂ reference electrode is developed as an alternative high-performance solution. This sensor exhibits a performance similar to that of a commercial glass pH sensor in some common sample matrices, particularly, an excellent pH sensitivity of 55.7 mV/pH, a hysteresis as low as 2.7 mV, and a drift below 2.2 mV/h. The developed sensor structure opens the way towards the development of a simple, cost effective, and robust pH sensor for pH analysis in various sample matrices.

Thermo-responsive human α-elastin self-assembled nanoparticles for protein delivery.

PubMed

Kim, Jae Dong; Jung, Youn Jae; Woo, Chang Hee; Choi, Young Chan; Choi, Ji Suk; Cho, Yong Woo

2017-01-01

Self-assembled nanoparticles based on PEGylated human α-elastin were prepared as a potential vehicle for sustained protein delivery. The α-elastin was extracted from human adipose tissue and modified with methoxypolyethyleneglycol (mPEG) to control particle size and enhance the colloidal stability. The PEGylated human α-elastin showed sol-to-particle transition with a lower critical solution temperature (LCST) of 25°C-40°C in aqueous media. The PEGylated human α-elastin nanoparticles (PhENPs) showed a narrow size distribution with an average diameter of 330±33nm and were able to encapsulate significant amounts of insulin and bovine serum albumin (BSA) upon simple mixing at low temperature in water and subsequent heating to physiological temperature. The release profiles of insulin and BSA showed sustained release for 72h. Overall, the thermo-responsive self-assembled PhENPs provide a useful tool for a range of protein delivery and tissue engineering applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and characterization of Mn quantum dots by bioreduction with water hyacinth.

PubMed

Rosano-Ortega, G; Schabes-Retchkiman, P; Zorrilla, C; Liu, H B; Canizal, G; Avila-Pérez, P; Ascencio, J A

2006-01-01

The bio-reduction method is reported as a part of a complimentary self-sustained technology, where bioremediation and metal particle production are related. The use of the characterization methods in this self sustainable technique open the expectative to be used for several other elements and with other plants, which will be discussed. However, the particular case of Mn nanoparticles involves an important option to generate nanoparticles in the range of 1-4 nanometers with a well controlled size and with a structure based on an fcc-like geometry for the smallest clusters and with more complex arrays for cluster greater than four shells, which involves magnetic moments significantly related to their atomistic configuration. At the same time, the use of the characterization methods establishes the dependence of the nanoparticle's size on the pH conditions used during the synthesis; small clusters in the range of 1-2 nm were generated using pH=5, and it was shown that for the smallest aggregates, simple polyhedron shapes are stable.

Isoelectric focusing in space

NASA Technical Reports Server (NTRS)

Bier, M.; Egen, N. B.; Mosher, R. A.; Twitty, G. E.

1982-01-01

The potential of space electrophoresis is conditioned by the fact that all electrophoretic techniques require the suppression of gravity-caused convection. Isoelectric focusing (IEF) is a powerful variant of electrophoresis, in which amphoteric substances are separated in a pH gradient according to their isoelectric points. A new apparatus for large scale IEF, utilizing a recycling principle, has been developed. In the ground-based prototype, laminar flow is provided by a series of parallel filter elements. The operation of the apparatus is monitored by an automated array of pH and ultraviolet absorption sensors under control of a desk-top computer. The apparatus has proven to be useful for the purification of a variety of enzymes, snake venom proteins, peptide hormones, and other biologicals, including interferon produced by genetic engineering techniques. In planning for a possible space apparatus, a crucial question regarding electroosmosis needs to be addressed To solve this problem, simple focusing test modules are planned for inclusion in an early Shuttle flight.

Computer model of hydroponics nutrient solution pH control using ammonium.

PubMed

Pitts, M; Stutte, G

1999-01-01

A computer simulation of a hydroponics-based plant growth chamber using ammonium to control pH was constructed to determine the feasibility of such a system. In nitrate-based recirculating hydroponics systems, the pH will increase as plants release hydroxide ions into the nutrient solution to maintain plant charge balance. Ammonium is an attractive alternative to traditional pH controls in an ALSS, but requires careful monitoring and control to avoid overdosing the plants with ammonium. The primary advantage of using NH4+ for pH control is that it exploits the existing plant nutrient uptake charge balance mechanisms to maintain solution pH. The simulation models growth, nitrogen uptake, and pH of a l-m2 stand of wheat. Simulation results indicated that ammonium-based control of nutrient solution pH is feasible using a proportional integral controller. Use of a 1 mmol/L buffer (Ka = 1.6 x 10(-6)) in the nutrient solution is required.

DNA sequence-directed shape change of photopatterned hydrogels via high-degree swelling

NASA Astrophysics Data System (ADS)

Cangialosi, Angelo; Yoon, ChangKyu; Liu, Jiayu; Huang, Qi; Guo, Jingkai; Nguyen, Thao D.; Gracias, David H.; Schulman, Rebecca

2017-09-01

Shape-changing hydrogels that can bend, twist, or actuate in response to external stimuli are critical to soft robots, programmable matter, and smart medicine. Shape change in hydrogels has been induced by global cues, including temperature, light, or pH. Here we demonstrate that specific DNA molecules can induce 100-fold volumetric hydrogel expansion by successive extension of cross-links. We photopattern up to centimeter-sized gels containing multiple domains that undergo different shape changes in response to different DNA sequences. Experiments and simulations suggest a simple design rule for controlled shape change. Because DNA molecules can be coupled to molecular sensors, amplifiers, and logic circuits, this strategy introduces the possibility of building soft devices that respond to diverse biochemical inputs and autonomously implement chemical control programs.

Treatment of hemorrhagic gastritis by antacid.

PubMed

Simonian, S J; Curtis, L E

1976-10-01

A simple and safe method of nonsurgical treatment for the control of massive acute gastric mucosal hemorrhage is described. The procedure was developed from experimental and clinical observations that the presence of gastric hydrocloric acid played an important part in the development and perpetuation of the entity. The treatment consists of complete neutralization of gastric acid with antacid to a pH of 7. The antacid is intermittently added and aspirate at 7. In a retrospective analysis, the hemorrhage was controlled in 44 of 49 patients (89%). Five patients who continued to bleed underwent surgery (10%). Three patients had vagotomy and pyloroplasty and their bleeding ceased without recurrence. Two patients underwent partial gastrectomy, but they developed recurrent bleeding and died. One patient whose bleeding has been controlled by vagotomy and pyloroplasty died without hemorrhage 10 days after operation. Of the 44 patients whose bleeding had been controlled by antacid, 11 patients died without hemorrhage one or more weeks later. These results of 89% control of hemorrhage compare favorably with those in the literature.

Treatment of hemorrhagic gastritis by antacid.

PubMed Central

Simonian, S J; Curtis, L E

1976-01-01

A simple and safe method of nonsurgical treatment for the control of massive acute gastric mucosal hemorrhage is described. The procedure was developed from experimental and clinical observations that the presence of gastric hydrocloric acid played an important part in the development and perpetuation of the entity. The treatment consists of complete neutralization of gastric acid with antacid to a pH of 7. The antacid is intermittently added and aspirate at 7. In a retrospective analysis, the hemorrhage was controlled in 44 of 49 patients (89%). Five patients who continued to bleed underwent surgery (10%). Three patients had vagotomy and pyloroplasty and their bleeding ceased without recurrence. Two patients underwent partial gastrectomy, but they developed recurrent bleeding and died. One patient whose bleeding has been controlled by vagotomy and pyloroplasty died without hemorrhage 10 days after operation. Of the 44 patients whose bleeding had been controlled by antacid, 11 patients died without hemorrhage one or more weeks later. These results of 89% control of hemorrhage compare favorably with those in the literature. PMID:13746

Voltammetric pH sensing using carbon electrodes: glassy carbon behaves similarly to EPPG.

PubMed

Lu, Min; Compton, Richard G

2014-09-21

Developing and building on recent work based on a simple sensor for pH determination using unmodified edge plane pyrolytic graphite (EPPG) electrodes, we present a voltammetric method for pH determination using a bare unmodified glassy carbon (GC) electrode. By exploiting the pH sensitive nature of quinones present on carbon edge-plane like sites within the GC, we show how GC electrodes can be used to measure pH. The electro-reduction of surface quinone groups on the glassy carbon electrode was characterised using cyclic voltammetry (CV) and optimised with square-wave voltammetry (SWV) at 298 K and 310 K. At both temperatures, a linear correlation was observed, corresponding to a 2 electron, 2 proton Nernstian response over the aqueous pH range 1.0 to 13.1. As such, unmodified glassy carbon electrodes are seen to be pH dependent, and the Nernstian response suggests its facile use for pH sensing. Given the widespread use of glassy carbon electrodes in electroanalysis, the approach offers a method for the near-simultaneous measurement and monitoring of pH during such analyses.

Anomalous pH Effect of Blue Proteorhodopsin.

PubMed

Yamada, Keisuke; Kawanabe, Akira; Yoshizawa, Susumu; Inoue, Kentaro; Kogure, Kazuhiro; Kandori, Hideki

2012-04-05

Proteorhodopsin (PR) is a light-driven proton pump found in marine bacteria, and thousands of PRs are classified into blue-absorbing PR (B-PR; λmax ≈ 490 nm) and green-absorbing PR (G-PR; λmax ≈ 525 nm). In this report, we present conversion of B-PR into G-PR using anomalous pH effect. B-PR in LC1-200, marine γ-proteobacteria, absorbs 497 and 513 nm maximally at pH 7 and 4, respectively, whose pH titration was reversible (pKa = 4.8). When pH was lowered from 4, the λmax was further red-shifted (528 nm at pH 2). This is unusual because blue shift occurs by chloride binding in the case of bacteriorhodopsin. Surprisingly, when pH was increased from 2 to 7, the λmax of this B-PR was further red-shifted to 540 nm, indicating that green-absorbing PR (PR540) is created only by changing pH. The present study reports the conformational flexibility of microbial rhodopsins, leading to the switch of absorbing color by a simple pH change.

[Determination of protopine and isocorydine in root of Dactylicapnos scandens by HPLC].

PubMed

Yan, Tian-qing; Yang, Yan-fang; Ai, Tie-min

2004-10-01

To establish a HPLC method for determination of protopine and isocorydine in root of Dactylicapnos scandens. The separation was performed in a PHENOMENEX-C18 column with a mobile phase of methanol-0.2% phosphoric acid (adjusted to pH 7.0 with triethylamine)(50:50), The detection wavelength was at 254 nm and the flow rate was 0.8 mL x min(-1). The average recovery of Protopine and Isocorydine was 97.9%, 98.6% respectively, and RSD 1.3%, 1.4%. This method is accurate, simple and reliable. It can be used for quality control of D. scandens.

Phase angle is related with inflammatory and oxidative stress biomarkers in older women.

PubMed

Tomeleri, Crisieli Maria; Cavaglieri, Cláudia Regina; de Souza, Mariana Ferreira; Cavalcante, Edilaine Fungari; Antunes, Melissa; Nabbuco, Hellen Clair Garcez; Venturini, Danielle; Barbosa, Decio Sabbatini; Silva, Analiza Mônica; Cyrino, Edilson Serpeloni

2018-02-01

The aim of this study was to examine the relation between phase angle (PhA) and inflammatory and oxidative stress biomarkers in older women. One hundred and fifty-five physically independent older women participated in this study (67.7±5.7years, 27.0±4.4kg/m 2 ). Inflammatory markers included interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and acute phase reactive protein (CRP). Oxidative stress biomarkers comprised superoxide dismutase (SOD), catalase (CAT), advanced oxidation protein products (AOPP), and total radical-trapping antioxidant potential (TRAP). A spectral bioelectrical impedance device was used to estimate resistance (R) and reactance (Xc) at frequency 50kHz, and subsequently PhA was calculated as arc-tangent (Xc/R)×180°/π. The covariates appendicular lean soft-tissue (ALST), trunk fat mass, and total body fat were determined by whole-body dual-energy X-ray absorptiometry. Linear regression analysis was conducted to further test if PhA is related with the dependent variables, after adjusting for potential covariates. After controlling for the potential covariates (age, trunk fat mass, ALST, and number of diseases) PhA exhibited a significant inverse relation with IL-6 (β=-0.97; P<0.01), TNF-α (β=-0.84; P<0.01), and CRP (β=-0.58; P<0.01). Conversely, PhA was significantly related to CAT (β=7.27; P<0.01), SOD (β=10.55; P<0.01) and TRAP (β=73.08; P<0.01). The AOPP did not demonstrate a significant correlation with PhA (P>0.05). Our findings show that PhA is a simple and relevant explanatory variable which is related inflammatory and stress oxidative markers in physically independent older women, regardless of age, number of diseases, and body composition. Copyright © 2017 Elsevier Inc. All rights reserved.

Speciation and precipitation of heavy metals in high-metal and high-acid mine waters from the Iberian Pyrite Belt (Portugal).

PubMed

Durães, Nuno; Bobos, Iuliu; da Silva, Eduardo Ferreira

2017-02-01

Acid mine waters (AMW) collected during high- and low-flow water conditions from the Lousal, Aljustrel, and São Domingos mining areas (Iberian Pyrite Belt) were physicochemically analyzed. Speciation calculation using PHREEQC code confirms the predominance of Me n+ and Me-SO 4 species in AMW samples. Higher concentration of sulfate species (Me-SO 4 ) than free ion species (Me n+ , i.e., Al, Fe, and Pb) were found, whereas opposite behavior is verified for Mg, Cu, and Zn. A high mobility of Zn than Cu and Pb was identified. The sulfate species distribution shows that Fe 3+ -SO 4 2- , SO 4 2- , HSO 4 - , Al-SO 4 , MgSO 4 0 , and CaSO 4 0 are the dominant species, in agreement with the simple and mixed metal sulfates and oxy-hydroxysulphates precipitated from AMW. The saturation indices (SI) of melanterite and epsomite show a positive correlation with Cu and Zn concentrations in AMW, which are frequently retained in simple metal sulfates. Lead is well correlated with jarosite and alunite (at least in very acid conditions) than with simple metal sulfates. The Pb for K substitution in jarosite occurs as increasing Pb concentration in solution. Lead mobility is also controlled by anglesite precipitation (a fairly insoluble sulfate), where a positive correlation was ascertained when the SI approaches equilibrium. The zeta potential of AMW decreased as pH increased due to colloidal particles aggregation, where water species change from SO 4 2- to OH - species during acid to alkaline conditions, respectively. The AMW samples were supersaturated in schwertmannite and goethite, confirmed by the Me n+ -SO 4 , Me n+ -Fe-O-OH, or Me n+ -S-O-Fe-O complexes identified by attenuated total reflectance infrared spectroscopy (ATR-IR). The ATR-IR spectrum of an AMW sample with pH 3.5 (sample L1) shows well-defined vibration plans attributed to SO 4 tetrahedron bonded with Fe-(oxy)hydroxides and the Me n+ sorbed by either SO 4 or Fe-(oxy)hydroxides. For samples with lower pH values (pH ~ 2.5-samples SD1 and SD4), the vibration plans attributed to Me n+ sorption are not evidenced, indicating its release in solution. The sorption of heavy metals on the first precipitated simple metal sulfates was ascertained by scanning electron microscopy coupled with X-ray spectrometry (SEM-EDX), where X-ray maps of Cu and Zn confirm a distribution of both metals in the melanterite structure.

High-density mammalian cell cultures in stirred-tank bioreactor without external pH control.

PubMed

Xu, Sen; Chen, Hao

2016-08-10

Maintaining desired pH is a necessity for optimal cell growth and protein production. It is typically achieved through a two-sided pH control loop on the bioreactor controller. Here we investigated cell culture processes with minimum or no pH control and demonstrated that high-density mammalian cell cultures could be maintained for long-term protein production without pH control. The intrinsic interactions between pCO2, lactate, and pH were leveraged to maintain culture pH. Fed-batch cultures at the same lower pH limit of 6.75 but different upper pH limits (7.05, 7.30, 7.45, 7.65) were evaluated in the 3L bioreactors and comparable results were obtained. Neither CO2 sparging nor base addition was required to control pH in the pH range of 6.75-7.65. The impact of sparger configurations (drilled hole sparger vs. frit sparger) and scales (3L vs. 200L) on CO2 accumulation and culture pH was also demonstrated. The same principle was applied in two perfusion cultures with steady state cell densities at 42.5±3.3 or 68.3±6.0×10(6)cells/mL with low cell specific perfusion rates (15±2 to 23±3pL/cell/day), achieving up to 1.9±0.1g/L/day bioreactor productivity. Culture pH level in the 3L perfusion bioreactors was steadily maintained by controlling the residual lactate and pCO2 levels without the requirement of external pH control for up to 40days with consistent productivity and product quality. Furthermore, culture pH could be potentially modulated via adjusting residual glucose levels and CO2 stripping capability in perfusion cultures. To the best of our knowledge, this is the first time a systematic study was performed to evaluate the long-term cell cultivation and protein production in stirred-tank bioreactors without external pH control. Copyright © 2016 Elsevier B.V. All rights reserved.

Real-time pH monitoring of industrially relevant enzymatic reactions in a microfluidic side-entry reactor (μSER) shows potential for pH control.

PubMed

Gruber, Pia; Marques, Marco P C; Sulzer, Philipp; Wohlgemuth, Roland; Mayr, Torsten; Baganz, Frank; Szita, Nicolas

2017-06-01

Monitoring and control of pH is essential for the control of reaction conditions and reaction progress for any biocatalytic or biotechnological process. Microfluidic enzymatic reactors are increasingly proposed for process development, however typically lack instrumentation, such as pH monitoring. We present a microfluidic side-entry reactor (μSER) and demonstrate for the first time real-time pH monitoring of the progression of an enzymatic reaction in a microfluidic reactor as a first step towards achieving pH control. Two different types of optical pH sensors were integrated at several positions in the reactor channel which enabled pH monitoring between pH 3.5 and pH 8.5, thus a broader range than typically reported. The sensors withstood the thermal bonding temperatures typical of microfluidic device fabrication. Additionally, fluidic inputs along the reaction channel were implemented to adjust the pH of the reaction. Time-course profiles of pH were recorded for a transketolase and a penicillin G acylase catalyzed reaction. Without pH adjustment, the former showed a pH increase of 1 pH unit and the latter a pH decrease of about 2.5 pH units. With pH adjustment, the pH drop of the penicillin G acylase catalyzed reaction was significantly attenuated, the reaction condition kept at a pH suitable for the operation of the enzyme, and the product yield increased. This contribution represents a further step towards fully instrumented and controlled microfluidic reactors for biocatalytic process development. © 2017 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement of the Performance of an Electrocoagulation Process System Using Fuzzy Control of pH.

PubMed

Demirci, Yavuz; Pekel, Lutfiye Canan; Altinten, Ayla; Alpbaz, Mustafa

2015-12-01

The removal efficiencies of electrocoagulation (EC) systems are highly dependent on the initial value of pH. If an EC system has an acidic influent, the pH of the effluent increases during the treatment process; conversely, if such a system has an alkaline influent, the pH of the effluent decreases during the treatment process. Thus, changes in the pH of the wastewater affect the efficiency of the EC process. In this study, we investigated the dynamic effects of pH. To evaluate approaches for preventing increases in the pH of the system, the MATLAB/Simulink program was used to develop and evaluate an on-line computer-based system for pH control. The aim of this work was to study Proportional-Integral-Derivative (PID) control and fuzzy control of the pH of a real textile wastewater purification process using EC. The performances and dynamic behaviors of these two control systems were evaluated based on determinations of COD, colour, and turbidity removal efficiencies.

Tailoring the structure of biphasic calcium phosphate via synthesis procedure

NASA Astrophysics Data System (ADS)

Mansour, S. F.; El-dek, S. I.; Ahmed, M. K.

2017-12-01

Nano calcium phosphate ceramics (CaPC) were synthesized using simple co-precipitation method at different preparation conditions. The selected Ca/P ratio with a variation of pH value lead to formation of dicalcium phosphate dihydrate (DCPD) at pH 5 and 6 while, hydroxyapatite (HAP) nano particles were formed at pH 9 and 12 at room temperature. The crystallite size was in the range of 15-55 nm depending on the obtained crystalline phase. The study displayed variation of decomposition depending on the annealing temperature. The significant note is the different transformation trend of each phase depending on the starting pH value. The HRTEM illustrated that the DCPD phase was formed as fibers with diameter around 4-6 nm, while HAP was formed in rod shape. The aspect ratio decreased from 6.6 at pH 9 to 4 at pH 12 which refer to the great influence of pH value on the morphology of calcium phosphates.

Preparation of a novel pH optical sensor using orange (II) based on agarose membrane as support.

PubMed

Heydari, Rouhollah; Hosseini, Mohammad; Amraei, Ahmadreza; Mohammadzadeh, Ali

2016-04-01

A novel and cost effective optical pH sensor was prepared using covalent immobilization of orange (II) indicator on the agarose membrane as solid support. The fabricated optical sensor was fixed into a sample holder of a spectrophotometer instrument for pH monitoring. Variables affecting sensor performance including pH of dye bonding to agarose membrane and dye concentration were optimized. The sensor responds to the pH changes in the range of 3.0-10.0 with a response time of 2.0 min and appropriate reproducibility (RSD ≤ 0.9%). No significant variation was observed on sensor response after increasing the ionic strength in the range of 0.0-0.5M of sodium chloride. Determination of pH using the proposed optical sensor is quick, simple, inexpensive, selective and sensitive in the pH range of 3.0-10.0. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of Biomimetic and Functionally Responsive Surfaces

NASA Astrophysics Data System (ADS)

Anastasiadis, Spiros H.

2010-03-01

Controlling the surface morphology of solids and manufacturing of functional surfaces with special responsive properties has been the subject of intense research. We report a methodology for creating multifunctionally responsive surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with different types of functional conformal coatings. Such surfaces exhibit controlled dual-scale roughness at the micro- and the nano-scale, which mimics the hierarchical morphology of water repellent natural surfaces. When a simple alkylsilane coating is utilized, highly water repellent surfaces are produced that quantitatively compare to those of the Lotus leaf. When a polymer brush is ``grafted from" these surfaces based on a pH-sensitive polymer, the surfaces can alter their behavior from super-hydrophilic (after immersion in a low pH buffer) to super-hydrophobic and water-repellent (following immersion to a high pH buffer). We quantify the water repellency of such responsive systems by drop elasticity measurements whereas we demonstrate that the water repellent state of such surface requires appropriate hydrophobicity of the functionalizing polymer. When a photo-responsive azobenzene-type polymer is deposited, a dynamic optical control of the wetting properties is obtained and the surface can be switched from super-hydrophilic (following UV irradiation) to hydrophobic (following green irradiation). In all the above cases we show that the principal effect of roughness is to cause amplification of the response to the different external stimuli.

Mild soaps and radiotherapy: a survey of the UK public to identify brands of soap considered mild and analysis of these to ascertain suitability for recommendation in radiotherapy departments.

PubMed

Robertson, K; Brown, P

2011-05-01

Cancer agencies recommend that patients use mild soap when undergoing external beam radiotherapy to minimise skin reactions. They define 'mild soap' as non-alkaline, lanolin free, unperfumed soap with a neutral pH. This study aimed to identify which soaps the UK public perceive as mild and ascertain if these were clinically mild and could potentially be recommended within radiotherapy departments. A survey of 237 participants identified eight top brands of mild soap, which were then tested for pH and analysed for potential irritants. All soaps were lanolin free and non-alkaline, with Simple and Johnson's the closest to pH 5.5. All contained fragrances except Simple and E45. Dove, Pears and Imperial Leather contained the highest concentration of fragrances. All soaps except E45 contained potential irritants. Only Simple and E45 fit the cancer agencies' definition of mild soap and could therefore be recommended for radiotherapy patients. Future research should identify current practices and recommendations in the UK as anecdotal evidence suggests large variations in skin care advice. Further scientific analysis could potentially identify cheaper brands that fit the definition of 'mild'. UK recommendations should be standardised and consistent with best practice to reduce skin reaction severity in radiotherapy patients. © 2010 Blackwell Publishing Ltd.

Electrochemical control of pH in a hydroponic nutrient solution

NASA Technical Reports Server (NTRS)

Schwartzkopf, S. H.

1986-01-01

The electrochemical pH control system described was found to provide a feasible alternative method of controlling nutrient solution pH for CELSS applications. The plants grown in nutrient solution in which the pH was controlled electrochemically showed no adverse effects. Further research into the design of a larger capacity electrode bridge for better control is indicated by the results of this experiment, and is currently under way.

Significance, definition, classification and risk factors of chronic kidney disease in South Africa.

PubMed

Meyers, A M

2015-03-01

Renal dysfunction or chronic kidney disease (CKD) is found in 10% of the global population and is classified into five stages according to the estimated glomerular filtration rate (eGFR). No matter where a patient lives, estimation of the GFR is mandatory for decision-making and obtained by the simple measurement of a serum creatinine level. The objective of diagnosing CKD lies in its future prevention, early detection and proper treatment, which will prevent or delay functional deterioration. Primary hypertension (PH) occurs in 25% of South Africa (SA)s black population and is the putative cause of stage 5 CKD in 40 - 60% of these patients. Moreover, in this group, stage 5 CKD occurs at a relatively young age (35 - 45 years) compared with other population groups in whom stage 5 CKD resulting from PH usually occurs between 60 and 70 years of age. In the cohort study, PH has been found in 12 - 16% of black school learners (mean age 17 years) compared with 1.8 - 2% of other ethnic groups (mixed race, Asian, white). End-stage renal failure (ESRF) is the fifth most common cause of death in SA, excluding post-traumatic cases. In addition, undiagnosed or poorly controlled PH is a potent risk factor for other cardiovascular disease (CVD), e.g. congestive cardiac failure, myocardial infarction, stroke. Significant protein is also associated with CVD and protein >1 g/d is a significant risk factor for ESRF.

A simple approach to design chitosan functionalized Fe3O4 nanoparticles for pH responsive delivery of doxorubicin for cancer therapy

NASA Astrophysics Data System (ADS)

Adimoolam, Mahesh G.; Amreddy, Narsireddy; Nalam, Madhusudana Rao; Sunkara, Manorama V.

2018-02-01

The use of magnetic nanoparticles (MNPs) in cancer therapy offer many advantages due to their unique size, physical and biocompatible properties. In this study we have developed a formulation, comprising of anti-cancer drug doxorubicin (Dox) conjugated to iron oxide nanoparticles via a pH sensitive imine linker. Different amounts of chitosan functionalized superparamagnetic iron oxide nanoparticles (Fe3O4-CHI) were synthesized in-situ by a simple hydrolysis method at room temperature. The synthesized nanoparticles were well characterized by TEM, Zeta Potential, TOC, XPS, TGA and VSM for their physicochemical properties. Dox was conjugated to the Fe3O4-CHI nanoparticles via a glutaraldehyde cross linker with the imine (sbnd Cdbnd Nsbnd) bond, which is sensitive to cleavage in the pH range of 4.4-6.4. The synthesized Fe3O4-Dox nanoparticles exhibited enhanced drug release in lower pH conditions which mimics the tumor microenvironment or intracellular organelles such as endosomes/lysosomes. The cell uptake and therapeutic efficacy of Fe3O4-Dox nanoparticles carried out in ovarian cancer cell (SK-OV-3) and breast cancer cell line (MCF7) showed improved therapeutic efficacy of Dox by nearly four-fold with Fe3O4-Dox nanoparticles.

Microwave-assisted one-step synthesis of white light-emitting carbon dot suspensions

NASA Astrophysics Data System (ADS)

Vanessa, Hinterberger; Wenshuo, Wang; Cornelia, Damm; Simon, Wawra; Martin, Thoma; Wolfgang, Peukert

2018-06-01

In this contribution, we demonstrate that an aqueous solution with adjustable fluorescent color, including white light emission, can be achieved by a rapid one-step microwave synthesis method resulting in a mixture of blue-emitting carbon dots (CDs) and the yellow-emitting 2,3-diaminophenazine (DAP). Aqueous mixtures of o-phenylene-diamine (oPD) and citric acid (CA) are used as precursors. The resulting product structures are analyzed by FT-IR and NMR spectroscopy and the size of the resulting CDs is determined by atomic force microscopy to be 1.1 ± 0.3 nm. The synthesized solution exhibits two fluorescence emission peaks at 430 and 560 nm, which were found to originate from the CDs and DAP, respectively. The intensity ratio of both fluorescence peaks depends on pH, which is driven by the protonation state of DAP. In consequence, the fluorescence emission color of the CD solution can be tuned precisely and reproducibly from blue to white to yellow by careful control of the pH. Finally, at a pH level of 5.4, at which there is equal blue and yellow emission intensity, a white light emitting solution can be successfully produced in a very fast and simple synthesis procedure.

A simple and rapid infrared-assisted self enzymolysis extraction method for total flavonoid aglycones extraction from Scutellariae Radix and mechanism exploration.

PubMed

Wang, Liping; Duan, Haotian; Jiang, Jiebing; Long, Jiakun; Yu, Yingjia; Chen, Guiliang; Duan, Gengli

2017-09-01

A new, simple, and fast infrared-assisted self enzymolysis extraction (IRASEE) approach for the extraction of total flavonoid aglycones (TFA) mainly including baicalein, wogonin, and oroxylin A from Scutellariae Radix is presented to enhance extraction yield. Extraction enzymolysis temperature, enzymolysis liquid-to-solid ratio, enzymolysis pH, enzymolysis time and infrared power, the factors affecting IRASEE procedure, were investigated in a newly designed, temperature-controlled infrared-assisted extraction (TC-IRAE) system to acquire the optimum analysis conditions. The results illustrated that IRASEE possessed great advantages in terms of efficiency and time compared with other conventional extraction techniques. Furthermore, the mechanism of IRASEE was preliminarily explored by observing the microscopic change of the samples surface structures, studying the main chemical compositions change of the samples before and after extraction and investigating the kinetics and thermodynamics at three temperature levels during the IRASEE process. These findings revealed that IRASEE can destroy the surface microstructures to accelerate the mass transfer and reduce the activation energy to intensify the chemical process. This integrative study presents a simple, rapid, efficient, and environmental IRASEE method for TFA extraction which has promising prospects for other similar herbal medicines. Graphical Abstract ᅟ.

Thermodynamic Driving Force of Hydrogen on Rumen Microbial Metabolism: A Theoretical Investigation

PubMed Central

van Lingen, Henk J.; Plugge, Caroline M.; Fadel, James G.; Kebreab, Ermias; Bannink, André; Dijkstra, Jan

2016-01-01

Hydrogen is a key product of rumen fermentation and has been suggested to thermodynamically control the production of the various volatile fatty acids (VFA). Previous studies, however, have not accounted for the fact that only thermodynamic near-equilibrium conditions control the magnitude of reaction rate. Furthermore, the role of NAD, which is affected by hydrogen partial pressure (PH2), has often not been considered. The aim of this study was to quantify the control of PH2 on reaction rates of specific fermentation pathways, methanogenesis and NADH oxidation in rumen microbes. The control of PH2 was quantified using the thermodynamic potential factor (FT), which is a dimensionless factor that corrects a predicted kinetic reaction rate for the thermodynamic control exerted. Unity FT was calculated for all glucose fermentation pathways considered, indicating no inhibition of PH2 on the production of a specific type of VFA (e.g., acetate, propionate and butyrate) in the rumen. For NADH oxidation without ferredoxin oxidation, increasing PH2 within the rumen physiological range decreased FT from unity to zero for different NAD+ to NADH ratios and pH of 6.2 and 7.0, which indicates thermodynamic control of PH2. For NADH oxidation with ferredoxin oxidation, increasing PH2 within the rumen physiological range decreased FT from unity at pH of 7.0 only. For the acetate to propionate conversion, FT increased from 0.65 to unity with increasing PH2, which indicates thermodynamic control. For propionate to acetate and butyrate to acetate conversions, FT decreased to zero below the rumen range of PH2, indicating full thermodynamic suppression. For methanogenesis by archaea without cytochromes, FT differed from unity only below the rumen range of PH2, indicating no thermodynamic control. This theoretical investigation shows that thermodynamic control of PH2 on individual VFA produced and associated yield of hydrogen and methane cannot be explained without considering NADH oxidation. PMID:27783615

Determination of total monomeric anthocyanin pigment content of fruit juices, beverages, natural colorants, and wines by the pH differential method: collaborative study.

PubMed

Lee, Jungmin; Durst, Robert W; Wrolstad, Ronald E

2005-01-01

This collaborative study was conducted to determine the total monomeric anthocyanin concentration by the pH differential method, which is a rapid and simple spectrophotometric method based on the anthocyanin structural transformation that occurs with a change in pH (colored at pH 1.0 and colorless at pH 4.5). Eleven collaborators representing commercial laboratories, academic institutions, and government laboratories participated. Seven Youden pair materials representing fruit juices, beverages, natural colorants, and wines were tested. The repeatability relative standard deviation (RSDr) varied from 1.06 to 4.16%. The reproducibility relative standard deviation (RSDR) ranged from 2.69 to 10.12%. The HorRat values were < or = 1.33 for all materials. The Study Director recommends that the method be adopted Official First Action.

Determination of the microenvironment-pH and charge and size characteristics of amino acids through their electrophoretic mobilities determined by CZE.

PubMed

Piaggio, Maria V; Peirotti, Marta B; Deiber, Julio A

2007-10-01

Effective electrophoretic mobility data of 20 amino acids reported in the literature are analyzed and interpreted through simple physicochemical models, which are able to provide estimates of coupled quantities like hydrodynamic shape factor, equivalent hydrodynamic radius (size), net charge, actual pK values of ionizing groups, partial charges of ionizing groups, hydration number, and pH near molecule (microenvironment-pH of the BGE). It is concluded that the modeling of the electrophoretic mobility of these analytes requires a careful consideration of hydrodynamic shape coupled to hydration. In the low range of pH studied here, distinctive hydrodynamic behaviors of amino acids are found. For instance, amino acids with basic polar and ionizing side chain remain with prolate shape for pH values varying from 1.99 to 3.2. It is evident that as the pH increases from low values, amino acids get higher hydrations as a consequence each analyte total charge also increases. This result is consistent with the monotonic increase of the hydrodynamic radius, which accounts for both the analyte and the quite immobilized water molecules defining the electrophoretic kinematical unit. It is also found that the actual or effective pK value of the alpha-carboxylic ionizing group of amino acids increases when the pH is changed from 1.99 to 3.2. Several limitations concerning the simple modeling of the electrophoretic mobility of amino acids are presented for further research.

The pH sensing characteristics of the extended-gate field-effect transistors of multi-walled carbon-nanotube thin film using low-temperature ultrasonic spray method.

PubMed

Chien, Yun-Shan; Yang, Po-Yu; Tsai, Wan-Lin; Li, Yu-Ren; Chou, Chia-Hsin; Chou, Jung-Chuan; Cheng, Huang-Chung

2012-07-01

A novel, simple and low-temperature ultrasonic spray method was developed to fabricate the multi-walled carbon-nanotubes (MWCNTs) based extended-gate field-effect transistors (EGFETs) as the pH sensor. With an acid-treated process, the chemically functionalized two-dimensional MWCNT network could provide plenty of functional groups which exhibit hydrophilic property and serve as hydrogen sensing sites. For the first time, the EGFET using a MWCNT structure could achieve a wide sensing rage from pH = 1 to pH = 13. Furthermore, the pH sensitivity and linearity values of the CNT pH-EGFET devices were enhanced to 51.74 mV/pH and 0.9948 from pH = 1 to pH = 13 while the sprayed deposition reached 50 times. The sensing properties of hydrogen and hydroxyl ions show significantly dependent on the sprayed deposition times, morphologies, crystalline and chemical bonding of acid-treated MWCNT. These results demonstrate that the MWCNT-EGFETs are very promising for the applications in the pH and biomedical sensors.

Suitability of 1-hexyl-3-methylimidazolium ionic liquids for the analysis of pharmaceutical formulations containing tricyclic antidepressants.

PubMed

Calabuig-Hernández, S; Peris-García, E; García-Alvarez-Coque, M C; Ruiz-Angel, M J

2018-07-20

The reversed-phase chromatographic behaviour of six tricyclic antidepressants (amitryptiline, clomipramine, doxepin, imipramine, nortryptiline and maprotiline) was examined in this work with acetonitrile-water mobile phases, in the absence and presence of the ionic liquids 1-hexyl-3-methylimidazolium chloride and 1-hexyl-3-methylimidazolium tetrafluoroborate, which have interesting features for the separation of basic compounds, in terms of peak shape combined with reduced retention. Tricyclic antidepressants are low polarity drugs that strongly associate to the alkyl chains of conventional stationary phases. They are also positively charged in the usual working pH range (2-8) in reversed-phase liquid chromatography, due to their strong basic character. In consequence, they may interact with the residual ionised silanols present in conventional silica-based stationary phases, which is translated in stronger retention, and tailed and broad peaks. A simple chromatographic procedure for the control of tricyclic antidepressants in pharmaceutical formulations was developed using a C8 column and a mobile phase containing 30% acetonitrile/10 mM 1-hexyl-3-methylimidazolium chloride at pH 3, with UV detection. Intra- and inter-day precisions were usually below +1.0%, and intra- and inter-day bias (trueness) ranged between ‒2.1% and +2.4%, and between ‒3.0% and +2.3%, respectively. Sample preparation was simple and only required solubilisation and filtration previous to injection. Copyright © 2017 Elsevier B.V. All rights reserved.

Visual detection of copper(II) ions in blood samples by controlling the leaching of protein-capped gold nanoparticles.

PubMed

Lee, Yen-Fei; Deng, Ting-Wei; Chiu, Wei-Jane; Wei, Tsao-Yen; Roy, Prathik; Huang, Chih-Ching

2012-04-21

We have developed a simple, low-cost, paper-based probe for the selective colorimetric detection of copper ions (Cu(2+)) in aqueous solutions. The bovine serum albumin (BSA)-modified 13.3-nm Au nanoparticle (BSA-Au NP) probe was designed to detect Cu(2+) ions using lead ions (Pb(2+)) and 2-mercaptoethanol (2-ME) as leaching agents in a glycine-NaOH (pH 12.0) solution. In addition, a nitrocellulose membrane (NCM) was used to trap the BSA-Au NPs, leading to the preparation of a nanocomposite film consisting of a BSA-Au NP-decorated membrane (BSA-Au NPs/NCM). The BSA-Au NPs probe operates on the principle that Cu deposition on the surface of the BSA-Au NPs inhibits their leaching ability, which is accelerated by Pb(2+) ions in the presence of 2-ME. Under optimal solution conditions (5 mM glycine-NaOH (pH 12.0), Pb(2+) (50 μM), and 2-ME (1.0 M)), the Pb(2+)/2-ME-BSA-Au NPs/NCM enabled the detection of Cu(2+) at nanomolar concentrations in aqueous solutions by the naked eye with high selectivity (at least 100-fold over other metal ions). In addition, this cost-effective probe allowed for the rapid and simple determination of Cu(2+) ions in not only natural water samples but also in a complex biological sample (in this case, blood sample).

Tuning interionic interaction by rationally controlling solution pH for highly selective colorimetric sensing of arginine.

PubMed

Qian, Qin; Hao, Jie; Ma, Wenjie; Yu, Ping; Mao, Lanqun

2016-04-01

Direct selective sensing of arginine in central nervous systems remains very essential to understanding of the molecular basis of some physiological events. This study presents the first demonstration on a simple yet effective method for arginine sensing with gold nanoparticles (Au-NPs) as the signal readout. The rationale for the method is based on the pH-dependent feature of the interionic interaction between cysteine and arginine. At pH 6.0, cysteine can only interact with arginine through the ion-pair interaction and such interaction can lead to the changes in both the solution color and UV-vis spectrum of the cysteine-protected Au-NPs upon the addition of arginine. These changes are further developed into an analytical strategy for effective sensing of arginine by rationally controlling the pH values of Au-NP dispersions with the ratio of the absorbance at 650 nm (A 650) to that at 520 nm (A 520) (A 650/A 520) as a parameter for analysis. The method is responsive to arginine without the interference from other species in the cerebral system; under the optimized conditions, the A 650/A 520 values are linear with the concentration of arginine within a concentration range from 0.80 to 64 μM, yet remain unchanged with the addition of other kinds of amino acids or the species in the central nervous system into the Au-NPs dispersion containing cysteine. The method demonstrated here is reliable and robust and could thus be used for detection of the increase of arginine in central nervous systems.

Analysis of microbial community and nitrogen transition with enriched nitrifying soil microbes for organic hydroponics.

PubMed

Saijai, Sakuntala; Ando, Akinori; Inukai, Ryuya; Shinohara, Makoto; Ogawa, Jun

2016-06-27

Nitrifying microbial consortia were enriched from bark compost in a water system by regulating the amounts of organic nitrogen compounds and by controlling the aeration conditions with addition of CaCO 3 for maintaining suitable pH. Repeated enrichment showed reproducible mineralization of organic nitrogen via the conversion of ammonium ions ([Formula: see text]) and nitrite ions ([Formula: see text]) into nitrate ions ([Formula: see text]). The change in microbial composition during the enrichment was investigated by PCR-DGGE analysis with a focus on prokaryote, ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and eukaryote cell types. The microbial transition had a simple profile and showed clear relation to nitrogen ions transition. Nitrosomonas and Nitrobacter were mainly detected during [Formula: see text] and [Formula: see text] oxidation, respectively. These results revealing representative microorganisms acting in each ammonification and nitrification stages will be valuable for the development of artificial simple microbial consortia for organic hydroponics that consisted of identified heterotrophs and autotrophic nitrifying bacteria.

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

Simple, Fast, and Sensitive Method for Quantification of Tellurite in Culture Media▿

PubMed Central

Molina, Roberto C.; Burra, Radhika; Pérez-Donoso, José M.; Elías, Alex O.; Muñoz, Claudia; Montes, Rebecca A.; Chasteen, Thomas G.; Vásquez, Claudio C.

2010-01-01

A fast, simple, and reliable chemical method for tellurite quantification is described. The procedure is based on the NaBH4-mediated reduction of TeO32− followed by the spectrophotometric determination of elemental tellurium in solution. The method is highly reproducible, is stable at different pH values, and exhibits linearity over a broad range of tellurite concentrations. PMID:20525868

A pH-based biosensor for detection of arsenic in drinking water.

PubMed

de Mora, K; Joshi, N; Balint, B L; Ward, F B; Elfick, A; French, C E

2011-05-01

Arsenic contaminated groundwater is estimated to affect over 100 million people worldwide, with Bangladesh and West Bengal being among the worst affected regions. A simple, cheap, accurate and disposable device is required for arsenic field testing. We have previously described a novel biosensor for arsenic in which the output is a change in pH, which can be detected visually as a colour change by the use of a pH indicator. Here, we present an improved formulation allowing sensitive and accurate detection of less than 10 ppb arsenate with static overnight incubation. Furthermore, we describe a cheap and simple high-throughput system for simultaneous monitoring of pH in multiple assays over time. Up to 50 samples can be monitored continuously over the desired time period. Cells can be stored and distributed in either air-dried or freeze-dried form. This system was successfully tested on arsenic-contaminated groundwater samples from the South East region of Hungary. We hope to continue to develop this sensor to produce a device suitable for field trials.

The role of pH control on biohydrogen production by single stage hybrid dark- and photo-fermentation.

PubMed

Zagrodnik, R; Laniecki, M

2015-10-01

The role of pH control on biohydrogen production by co-culture of dark-fermentative Clostridium acetobutylicum and photofermentative Rhodobacter sphaeroides was studied. Single stage dark fermentation, photofermentation and hybrid co-culture systems were studied at different values of controlled and uncontrolled pH. Increasing pH during dark fermentation resulted in lower hydrogen production rate (HPR) and longer lag time for both controlled and uncontrolled conditions. However, it only slightly affected cumulative H2 volume. Results have shown that pH control at pH 7.5 increased photofermentative hydrogen production from 0.966 to 2.502 L H2/L(medium) when compared to uncontrolled process. Fixed pH value has proven to be an important control strategy also for the hybrid process and resulted in obtaining balanced co-culture of dark and photofermentative bacteria. Control of pH at 7.0 was found optimum for bacteria cooperation in the co-culture what resulted in obtaining 2.533 L H2/L(medium) and H2 yield of 6.22 mol H2/mol glucose. Copyright © 2015 Elsevier Ltd. All rights reserved.

Catalytic wet-oxidation of a mixed liquid waste: COD and AOX abatement.

PubMed

Goi, D; de Leitenburg, C; Trovarelli, A; Dolcetti, G

2004-12-01

A series of catalytic wet oxidation (CWO) reactions, at temperatures of 430-500 K and in a batch bench-top pressure vessel were carried out utilizing a strong wastewater composed of landfill leachate and heavily organic halogen polluted industrial wastewater. A CeO2-SiO2 mixed oxide catalyst with large surface area to assure optimal oxidation performance was prepared. The catalytic process was examined during batch reactions controlling Chemical Oxygen Demand (COD) and Adsorbable Organic Halogen (AOX) parameters, resulting AOX abatement to achieve better effect. Color and pH were also controlled during batch tests. A simple first order-two stage reaction behavior was supposed and verified with the considered parameters. Finally an OUR test was carried out to evaluate biodegradability changes of wastewater as a result of the catalytic reaction.

Graphite Screen-Printed Electrodes Applied for the Accurate and Reagentless Sensing of pH.

PubMed

Galdino, Flávia E; Smith, Jamie P; Kwamou, Sophie I; Kampouris, Dimitrios K; Iniesta, Jesus; Smith, Graham C; Bonacin, Juliano A; Banks, Craig E

2015-12-01

A reagentless pH sensor based upon disposable and economical graphite screen-printed electrodes (GSPEs) is demonstrated for the first time. The voltammetric pH sensor utilizes GSPEs which are chemically pretreated to form surface immobilized oxygenated species that, when their redox behavior is monitored, give a Nernstian response over a large pH range (1-13). An excellent experimental correlation is observed between the voltammetric potential and pH over the entire pH range of 1-13 providing a simple approach with which to monitor solution pH. Such a linear response over this dynamic pH range is not usually expected but rather deviation from linearity is encountered at alkaline pH values; absence of this has previously been attributed to a change in the pKa value of surface immobilized groups from that of solution phase species. This non-deviation, which is observed here in the case of our facile produced reagentless pH sensor and also reported in the literature for pH sensitive compounds immobilized upon carbon electrodes/surfaces, where a linear response is observed over the entire pH range, is explained alternatively for the first time. The performance of the GSPE pH sensor is also directly compared with a glass pH probe and applied to the measurement of pH in "real" unbuffered samples where an excellent correlation between the two protocols is observed validating the proposed GSPE pH sensor.

An ammonium sulfate sensitive chitinase from Streptomyces sp. CS501.

PubMed

Rahman, Md Arifur; Choi, Yun Hee; Pradeep, G C; Yoo, Jin Cheol

2014-12-01

A chitinase from Streptomyces sp. CS501 was isolated from the Korean soil sample, purified by single-step chromatography, and biochemically characterized. The extracellular chitinase (Ch501) was purified to 4.60 fold with yield of 28.74 % using Sepharose Cl-6B column. The molecular mass of Ch501 was approximately 43 kDa as estimated by SDS-PAGE and zymography. The enzyme (Ch501) was found to be stable over a broad pH range (5.0-10.0) and temperature (up to 50 °C), and have an optimum temperature of 60 °C. N-terminal sequence of Ch501 was AAYDDAAAAA. Intriguingly, Ch501 was highly sensitive to ammonium sulfate but it's completely suppressed activity was recovered after desalting out. TLC analysis of Ch501 showed the production of N-acetyl D-glucosamine (GlcNAc) and Diacetylchitobiose (GlcNAc)2, as a principal hydrolyzed product. Ch501 shows antifungal activity against Fusarium solani and Aspergillus brasiliensis, which can be used for the biological control of fungus. As has been simple in purification, stable in a broad range of pH, ability to produce oligosaccharides, and antifungal activity showed that Ch501 has potential applications in industries as for chitooligosaccharides production used as prebiotics and/or for the biological control of plant pathogens in agriculture.

How do directors of public health perceive leadership?

PubMed

McAreav, M J; Alimo-Metcalfe, B; Connelly, J

2001-01-01

This study examines how directors of public health (DsPH) perceive effective leadership. Kelly's repertory grid technique is used. A total of 13 out of a possible 14 DsPH in one NHS region of England were interviewed. Qualitative and quantitative analysis were carried out. The findings show that male DsPH (n = 8) rate their leadership ability more highly than do female DsPH (n = 5). Qualitative analysis produced a number of categories of constructs, some of which are perceived to be indicative of effective leadership, these being "working for others", "personal attributes", "vision and innovation" and "courage and integrity" Some categories appear to be applicable only to the UK (or to public health) and not to the existing dominant US models of leadership. In general, DsPH perceptions of effective leadership converge with current theories; most specifically the UK-based theories. This study therefore refutes any simple extrapolation of US theories of leadership to UK health organisations.

Design of an optically stable pH sensor based on immobilization of Giemsa on triacetylcellulose membrane.

PubMed

Khodadoust, Saeid; Kouri, Narges Cham; Talebiyanpoor, Mohammad Sharif; Deris, Jamile; Pebdani, Arezou Amiri

2015-12-01

In this work a simple, inexpensive, and sensitive optical sensor based on triacetylcellulose membrane as solid support was developed by using immobilization of Giemsa indicator for pH measurement. In this method, the influence variables on the membrane performance including pH concentration of indicator, response time, ionic strength, and reversibility were investigated. At optimum values of all variables the response of optical pH sensor is linear in the pH range of 3.0-12.0. This optical sensor was produced through simultaneous binding of the Giemsa on the activated triacetylcellulose membrane which responded to the pH changes in a broader linear range within less than 2.0 min and suitable reproducibility (RSD<5%). Stability results showed that this sensor was stable after 6 months of storage in the water/ethanol (50:50, v/v) solution without any measurable divergence in response properties (less than 5% RSD). Copyright © 2015 Elsevier B.V. All rights reserved.

Computer simulation of immobilized pH gradients at acidic and alkaline extremes - A quest for extended pH intervals

NASA Technical Reports Server (NTRS)

Mosher, Richard A.; Bier, Milan; Righetti, Pier Giorgio

1986-01-01

Computer simulations of the concentration profiles of simple biprotic ampholytes with Delta pKs 1, 2, and 3, on immobilized pH gradients (IPG) at extreme pH values (pH 3-4 and pH 10-11) show markedly skewed steady-state profiles with increasing kurtosis at higher Delta pK values. Across neutrality, all the peaks are symmetric irrespective of their Delta pK values, but they show very high contribution to the conductivity of the background gel and significant alteration of the local buffering capacity. The problems of skewness, due to the exponential conductivity profiles at low and high pHs, and of gel burning due to a strong electroosmotic flow generated by the net charges in the gel matrix, also at low and high pHs, are solved by incorporating in the IPG gel a strong viscosity gradient. This is generated by a gradient of linear polyacrylamide which is trapped in the gel by the polymerization process.

Effects of different artificial ageing methods on the degradation of adhesive-dentine interfaces.

PubMed

Deng, Donglai; Yang, Hongye; Guo, Jingmei; Chen, Xiaohui; Zhang, Weiping; Huang, Cui

2014-12-01

To compare the effects of four commonly used artificial ageing methods (water storage, thermocycling, NaOCl storage and pH cycling) on the degradation of adhesive-dentine interfaces. Fifty molars were sectioned parallel to the occlusal plane, polished and randomly divided into two adhesive groups: An etch-and-rinse adhesive Adper SingleBond 2 and a self-etch adhesive G-Bond. After the composite built up, the specimens from each adhesive group were sectioned into beams, which were then assigned to one of the following groups: Group 1 (control), 24h of water storage; Group 2, 6 months of water storage; Group 3, 10,000 runs of thermocycling; Group 4, 1h of 10% NaOCl storage; and Group 5, 15 runs of pH cycling. The microtensile bond strengths were then tested. The failure modes were classified with a stereomicroscope and representative interface was analyzed with a field-emission scanning electron microscopy (FESEM). Nanoleakage expression was evaluated through FESEM in the backscattered mode. The four artificial ageing methods decreased the bonding strength to nearly 50% and increased the nanoleakage expression of both adhesive systems compared with the control treatment. Adhesive failures were the predominant fracture modes in all groups. However, differences in detailed morphology were observed among the different groups. Water storage, thermocycling, NaOCl storage and pH cycling could obtain similar degradation effectiveness through appropriate parameter selection. Each in vitro artificial ageing method had its own mechanisms, characteristics and application scope for degrading the adhesive-dentin interfaces. Water storage is simple, low-cost but time-consuming; thermocycling lacks of a standard agreement; NaOCl storage is time-saving but mainly degrades the organic phase; pH cycling can resemble cariogenic condition but needs further studies. Researchers focusing on bonding durability studies should be deliberate in selecting an appropriate ageing model based on the differences of test material, purpose and time. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Synthesis and Photoluminescent Properties of CaMoO₄:Eu³⁺ Nanocrystals by a Soft Chemical Route.

PubMed

Li, Fuhai; Yu, Lixin; Sun, Jiaju; Li, Songchu; Wei, Shuilin

2017-04-01

In this paper, the CaMoO4:Eu3+ phosphors were prepared by a simple hydrothermal method assisted by the citric acid as the surfactant, and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and fluorescent spectrophotometry. The results of XRD show that the as-prepared samples are single phase. The process of the Ostwald ripening is controlled by the content of the citric acid in the hydrothermal reaction. The pH value of the precursor affects the shift of the charge transition band (CTB) in the excitation spectra. The reaction condition can strongly affect the luminescent intensity of the samples.

Biosynthesis of silver and platinum nanoparticles using orange peel extract: characterisation and applications.

PubMed

Castro, Laura; Blázquez, María Luisa; González, Felisa; Muñoz, Jesús Ángel; Ballester, Antonio

2015-10-01

This study focuses on the green synthesis of noble metal nanoparticles (silver (Ag) and platinum (Pt)) and how the size and shape of the nanoparticles produced can be controlled through changes in the initial pH value of the precursor solution. The nanoparticles were characterised by ultra-violet-visible spectroscopy, transmission electron microscopy and X-ray diffraction. This simple and environmentally friendly method allows the synthesis of diverse nanostructures in the absence of a surfactant or polymer to direct nanoparticle growth, and without externally adding seed crystallites. The antibacterial effects of Ag nanoparticles and catalytic properties of Pt nanoparticles were explored for future promising biotechnological approaches in different fields.

A passion for precision

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

None

2010-05-19

For more than three decades, the quest for ever higher precision in laser spectroscopy of the simple hydrogen atom has inspired many advances in laser, optical, and spectroscopic techniques, culminating in femtosecond laser optical frequency combs  as perhaps the most precise measuring tools known to man. Applications range from optical atomic clocks and tests of QED and relativity to searches for time variations of fundamental constants. Recent experiments are extending frequency comb techniques into the extreme ultraviolet. Laser frequency combs can also control the electric field of ultrashort light pulses, creating powerful new tools for the emerging field of attosecondmore » science.Organiser(s): L. Alvarez-Gaume / PH-THNote: * Tea & coffee will be served at 16:00.« less

Optical characterization of the new nanocomposite SBMA/Eu(TTA)3(Ph3PO)2

NASA Astrophysics Data System (ADS)

Bordian, Olga; Verlan, Victor; Culeac, Ion; Iovu, Mihail; Zubareva, Vera; Nistor, Iurie

2015-02-01

We describe a new nanocomposite material based on the copolymer of styrene with butyl methacrylate (1:1) (SBMA), and coordinating compound of Europium(III) Eu(TTA)3(Ph3PO)2. The SBMA/Eu(TTA)3(Ph3PO)2 nanocomposite was prepared by a simple technology and can be obtained in the form of optical fibers, thin films and planar waveguides on various substrates with large area. Experimental results on optical transmission and photoluminescence spectroscopy are presented. The nanocomposite exhibits a strong photoluminescence emission in the range 560-750 nm, with the main photoluminescence band at 613 nm.

Variation in the p-H of faeces in disease.

PubMed

Madanagopalan, N; Nadar, S A; Subramaniam, R

1970-04-01

Although it is highly unlikely that a disease can be definitively diagnosed from a study of the pH of the faeces alone, the present study has helped to dispel the past belief that the pH of faeces in acute amoebic dysentery is more likely to be acidic. Culture for other pathogenic organisms has not been done in the present series of cases, but the chances of the coincidence of bacillary dysentery in this group would probably not have been significant. Further, in the past a simple litmus paper test was suggested to differentiate an amoebic dysentery from a bacillary dysentery, a procedure which can no longer hold good.

Prebiotic Peptide (Amide) Bond Synthesis Accelerated by Glycerol and Bicarbonate Under Neutral to Alkaline Dry-Down Conditions

NASA Technical Reports Server (NTRS)

Forsythe, J. G.; Weber, A. L.

2017-01-01

Past studies of prebiotic peptide bond synthesis have generally been carried out in the acidic to neutral pH range [1, 2]. Here we report a new process for peptide bond (amide) synthesis in the neutral to alkaline pH range that involves simple dry-down heating of amino acids in the presence of glycerol and bicarbonate. Glycerol was included in the reaction mixture as a solvent and to provide hydroxyl groups for possible formation of ester intermediates previously implicated in peptide bond synthesis under acidic to neutral conditions [1]. Bicarbonate was added to raise the reaction pH to 8-9.

Simple apparatus for polarization sensing of analytes

NASA Astrophysics Data System (ADS)

Gryczynski, Zygmunt; Gryczynski, Ignacy; Lakowicz, Joseph R.

2000-09-01

We describe a simple device for fluorescence sensing based on an unexpansive light source, a dual photocell and a Watson bridge. The emission is detected from two fluorescent samples, one of which changes intensity in response to the analyte. The emission from these two samples is observed through two orthogonally oriented polarizers and an analyzer polarizer. The latter polarizer is rotated to yield equal intensities from both sides of the dual photocell, as determined by a zero voltage from the Watson bridge. Using this device, we are able to measure fluorescein concentration to an accuracy near 2% at 1 (mu) M fluorescein, and pH values accurate to +/- 0.02 pH units. We also use this approach with a UV hand lamp and a glucose-sensitive protein to measure glucose concentrations near 2 (mu) M to an accuracy of +/- 0.1 (mu) M. This approach requires only simple electronics, which can be battery powered. Additionally, the method is generic, and can be applied with any fluorescent sample that displays a change in intensity. One can imagine this approach being used to develop portable point-of-care clinical devices.

Intra-domain phage display (ID-PhD) of peptides and protein mini-domains censored from canonical pIII phage display.

PubMed

Tjhung, Katrina F; Deiss, Frédérique; Tran, Jessica; Chou, Ying; Derda, Ratmir

2015-01-01

In this paper, we describe multivalent display of peptide and protein sequences typically censored from traditional N-terminal display on protein pIII of filamentous bacteriophage M13. Using site-directed mutagenesis of commercially available M13KE phage cloning vector, we introduced sites that permit efficient cloning using restriction enzymes between domains N1 and N2 of the pIII protein. As infectivity of phage is directly linked to the integrity of the connection between N1 and N2 domains, intra-domain phage display (ID-PhD) allows for simple quality control of the display and the natural variations in the displayed sequences. Additionally, direct linkage to phage propagation allows efficient monitoring of sequence cleavage, providing a convenient system for selection and evolution of protease-susceptible or protease-resistant sequences. As an example of the benefits of such an ID-PhD system, we displayed a negatively charged FLAG sequence, which is known to be post-translationally excised from pIII when displayed on the N-terminus, as well as positively charged sequences which suppress production of phage when displayed on the N-terminus. ID-PhD of FLAG exhibited sub-nanomolar apparent Kd suggesting multivalent nature of the display. A TEV-protease recognition sequence (TEVrs) co-expressed in tandem with FLAG, allowed us to demonstrate that 99.9997% of the phage displayed the FLAG-TEVrs tandem and can be recognized and cleaved by TEV-protease. The residual 0.0003% consisted of phage clones that have excised the insert from their genome. ID-PhD is also amenable to display of protein mini-domains, such as the 33-residue minimized Z-domain of protein A. We show that it is thus possible to use ID-PhD for multivalent display and selection of mini-domain proteins (Affibodies, scFv, etc.).

Evaluation of red cell distribution width in dogs with pulmonary hypertension.

PubMed

Swann, James W; Sudunagunta, Siddharth; Covey, Heather L; English, Kate; Hendricks, Anke; Connolly, David J

2014-12-01

To compare red cell distribution width (RDW) between dogs with different causes of pulmonary hypertension (PH) and a control dog population to determine whether RDW was correlated with severity of PH as measured by echocardiography. A further aim was to determine the prognostic significance of increased RDW for dogs with PH. Forty-four client-owned dogs with PH and 79 control dogs presented to a single tertiary referral institution. Signalment, clinical pathological and echocardiographic data were obtained retrospectively from the medical records of dogs with PH, and RDW measured on a Cell-Dyn 3500 was compared between dogs with pre- and post-capillary PH and a control population. Referring veterinary surgeons were contacted for follow-up information and Kaplan-Meier analysis was conducted to investigate differences in survival time between affected dogs with different RDW values. The RDW was significantly greater in dogs with pre-capillary PH compared to control dogs. There was no difference in median survival times between dogs with PH divided according to RDW values. The RDW was positively correlated with mean corpuscular volume and haematocrit in dogs with PH, but did not correlate with echocardiographic variables. An association was found between dogs with PH and increased RDW; however there was considerable overlap in values between control dogs and dogs with PH. The RDW was not associated with survival in this study. Copyright © 2014 Elsevier B.V. All rights reserved.

Reflection-mode micro-spherical fiber-optic probes for in vitro real-time and single-cell level pH sensing.

PubMed

Yang, Qingbo; Wang, Hanzheng; Lan, Xinwei; Cheng, Baokai; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

2015-02-01

pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70 μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2', 7'-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks. By tuning the alkoxide mixing ratio and adjusting hexamethyldisilazane (HMDS) priming procedure, the sensor can be optimized to have high stability and pH sensing ability. The in vitro real-time sensing capability was then demonstrated in a simple spectroscopic way, and showed linear measurement responses with a pH resolution up to an average of 0.049 pH unit within a narrow, but biological meaningful pH range of 6.12-7.81. Its novel characterizations of high spatial resolution, reflection mode operation, fast response and high stability, great linear response within biological meaningful pH range and high pH resolutions, make this novel pH probe a very cost-effective tool for chemical/biological sensing, especially within the single cell level research field.

Reflection-mode micro-spherical fiber-optic probes for in vitro real-time and single-cell level pH sensing

PubMed Central

Yang, Qingbo; Wang, Hanzheng; Lan, Xinwei; Cheng, Baokai; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

2014-01-01

pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70 μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2′, 7′-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks. By tuning the alkoxide mixing ratio and adjusting hexamethyldisilazane (HMDS) priming procedure, the sensor can be optimized to have high stability and pH sensing ability. The in vitro real-time sensing capability was then demonstrated in a simple spectroscopic way, and showed linear measurement responses with a pH resolution up to an average of 0.049 pH unit within a narrow, but biological meaningful pH range of 6.12–7.81. Its novel characterizations of high spatial resolution, reflection mode operation, fast response and high stability, great linear response within biological meaningful pH range and high pH resolutions, make this novel pH probe a very cost-effective tool for chemical/biological sensing, especially within the single cell level research field. PMID:25530670

Conformal self-assembled thin films for optical pH sensors

NASA Astrophysics Data System (ADS)

Topasna, Daniela M.; Topasna, Gregory A.; Liu, Minghanbo; Tseng, Ching-Hung

2016-04-01

Simple, reliable, lightweight, and inexpensive thin films based sensors are still in intense development and high demand in many applications such as biomedical, industrial, environmental, military, and consumer products. One important class of sensors is the optical pH sensor. In addition, conformal thin film based sensors extend the range of application for pH optical sensors. We present the results on the fabrication and characterization of optical pH sensing coatings made through ionic self-assembled technique. These thin films are based on the combination of a polyelectrolyte and water-soluble organic dye molecule Direct Yellow 4. A series of films was fabricated and characterized in order to determine the optimized parameters of the polymer and of the organic dye solutions. The optical pH responses of these films were also studied. The transparent films were immersed in solutions at various temperature and pH values. The films are stable when immersed in solutions with pH below 9.0 and temperatures below 90 °C and they maintain their performance after longer immersion times. We also demonstrate the functionality of these coatings as conformal films.

A single pH fluorescent probe for biosensing and imaging of extreme acidity and extreme alkalinity.

PubMed

Chao, Jian-Bin; Wang, Hui-Juan; Zhang, Yong-Bin; Li, Zhi-Qing; Liu, Yu-Hong; Huo, Fang-Jun; Yin, Cai-Xia; Shi, Ya-Wei; Wang, Juan-Juan

2017-07-04

A simple tailor-made pH fluorescent probe 2-benzothiazole (N-ethylcarbazole-3-yl) hydrazone (Probe) is facilely synthesized by the condensation reaction of 2-hydrazinobenzothiazole with N-ethylcarbazole-3-formaldehyde, which is a useful fluorescent probe for monitoring extremely acidic and alkaline pH, quantitatively. The pH titrations indicate that Probe displays a remarkable emission enhancement with a pK a of 2.73 and responds linearly to minor pH fluctuations within the extremely acidic range of 2.21-3.30. Interestingly, Probe also exhibits strong pH-dependent characteristics with pK a 11.28 and linear response to extreme-alkalinity range of 10.41-12.43. In addition, Probe shows a large Stokes shift of 84 nm under extremely acidic and alkaline conditions, high selectivity, excellent sensitivity, good water-solubility and fine stability, all of which are favorable for intracellular pH imaging. The probe is further successfully applied to image extremely acidic and alkaline pH values fluctuations in E. coli cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Highly pH-responsive sensor based on amplified spontaneous emission coupled to colorimetry.

PubMed

Zhang, Qi; Castro Smirnov, Jose R; Xia, Ruidong; Pedrosa, Jose M; Rodriguez, Isabel; Cabanillas-Gonzalez, Juan; Huang, Wei

2017-04-07

We demonstrated a simple, directly-readable approach for high resolution pH sensing. The method was based on sharp changes in Amplified Spontaneous Emission (ASE) of a Stilbene 420 (ST) laser dye triggered by the pH-dependent absorption of Bromocresol Green (BG). The ASE threshold of BG:ST solution mixtures exhibited a strong dependence on BG absorption, which was drastically changed by the variations of the pH of BG solution. As a result, ASE on-off or off-on was observed with different pH levels achieved by ammonia doping. By changing the concentration of the BG solution and the BG:ST blend ratio, this approach allowed to detect pH changes with a sensitivity down to 0.05 in the 10-11 pH range.

A biographical note on Max Friedrich (1856-1887), Wundt's first PhD student in experimental psychology.

PubMed

Domanski, Cezary W

2004-01-01

This article unveils some previously unknown facts about the short life of Max Friedrich (1856-1887), the author in 1881 of the first PhD dissertation on experimental psychology, written under the supervision of Wilhelm Wundt: "On the Duration of Apperception for Simple and Complex Visual Stimuli." The article describes Friedrich's family background and life, professional career as a teacher, and works in psychology and mathematics. Copyright 2004 Wiley Periodicals, Inc.

Hydroxyproline Metabolism and Oxalate Synthesis in Primary Hyperoxaluria.

PubMed

Fargue, Sonia; Milliner, Dawn S; Knight, John; Olson, Julie B; Lowther, W Todd; Holmes, Ross P

2018-06-01

Background Endogenous oxalate synthesis contributes to calcium oxalate stone disease and is markedly increased in the inherited primary hyperoxaluria (PH) disorders. The incomplete knowledge regarding oxalate synthesis complicates discovery of new treatments. Hydroxyproline (Hyp) metabolism results in the formation of oxalate and glycolate. However, the relative contribution of Hyp metabolism to endogenous oxalate and glycolate synthesis is not known. Methods To define this contribution, we performed primed, continuous, intravenous infusions of the stable isotope [ 15 N, 13 C 5 ]-Hyp in nine healthy subjects and 19 individuals with PH and quantified the levels of urinary 13 C 2 -oxalate and 13 C 2 -glycolate formed using ion chromatography coupled to mass detection. Results The total urinary oxalate-to-creatinine ratio during the infusion was 73.1, 70.8, 47.0, and 10.6 mg oxalate/g creatinine in subjects with PH1, PH2, and PH3 and controls, respectively. Hyp metabolism accounted for 12.8, 32.9, and 14.8 mg oxalate/g creatinine in subjects with PH1, PH2, and PH3, respectively, compared with 1.6 mg oxalate/g creatinine in controls. The contribution of Hyp to urinary oxalate was 15% in controls and 18%, 47%, and 33% in subjects with PH1, PH2, and PH3, respectively. The contribution of Hyp to urinary glycolate was 57% in controls, 30% in subjects with PH1, and <13% in subjects with PH2 or PH3. Conclusions Hyp metabolism differs among PH types and is a major source of oxalate synthesis in individuals with PH2 and PH3. In patients with PH1, who have the highest urinary excretion of oxalate, the major sources of oxalate remain to be identified. Copyright © 2018 by the American Society of Nephrology.

Minimal proton channel enables H2 oxidation and production with a water-soluble nickel-based catalyst.

PubMed

Dutta, Arnab; Lense, Sheri; Hou, Jianbo; Engelhard, Mark H; Roberts, John A S; Shaw, Wendy J

2013-12-11

Hydrogenase enzymes use first-row transition metals to interconvert H2 with protons and electrons, reactions that are important for the storage and recovery of energy from intermittent sources such as solar, hydroelectric, and wind. Here we present Ni(P(Cy)2N(Gly)2)2, a water-soluble molecular electrocatalyst with the amino acid glycine built into the diphosphine ligand framework. Proton transfer between the outer coordination sphere carboxylates and the second coordination sphere pendant amines is rapid, as observed by cyclic voltammetry and FTIR spectroscopy, indicating that the carboxylate groups may participate in proton transfer during catalysis. This complex oxidizes H2 (1-33 s(-1)) at low overpotentials (150-365 mV) over a range of pH values (0.1-9.0) and produces H2 under identical solution conditions (>2400 s(-1) at pH 0.5). Enzymes employ proton channels for the controlled movement of protons over long distances-the results presented here demonstrate the effects of a simple two-component proton channel in a synthetic molecular electrocatalyst.

Removal of iron and manganese using biological roughing up flow filtration technology.

PubMed

Pacini, Virginia Alejandra; María Ingallinella, Ana; Sanguinetti, Graciela

2005-11-01

The removal of iron and manganese from groundwater using biological treatment methods is almost unknown in Latin America. Biological systems used in Europe are based on the process of double rapid biofiltration during which dissolved oxygen and pH need to be strictly controlled in order to limit abiotic iron oxidation. The performance of roughing filter technology in a biological treatment process for the removal of iron and manganese, without the use of chemical agents and under natural pH conditions was studied. Two pilot plants, using two different natural groundwaters, were operated with the following treatment line: aeration, up flow roughing filtration and final filtration (either slow or rapid). Iron and manganese removal efficiencies were found to be between 85% and 95%. The high solid retention capability of the roughing filter means that it is possible to remove iron and manganese simultaneously by biotic and abiotic mechanisms. This system combines simple, low-cost operation and maintenance with high iron and manganese removal efficiencies, thus constituting a technology which is particularly suited to small waterworks.

pH-sensitive nanocargo based on smart polymer functionalized graphene oxide for site-specific drug delivery.

PubMed

Kavitha, Thangavelu; Abdi, Syed Izhar Haider; Park, Soo-Young

2013-04-14

Graphene oxide (GO) was functionalized covalently with pH-sensitive poly(2-(diethylamino) ethyl methacrylate) (PDEA) by surface-initiated in situ atom transfer radical polymerization. The structure of the PDEA-grafted GO (GO-PDEA) were examined by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and atomic force microscopy. The grafted PDEA endowed the GO sheets with good solubility and stability in physiological solutions. Simple physisorption by π-π stacking and hydrophobic interactions on GO-PDEA can be used to load camptothecin (CPT), a widely used water-insoluble cancer drug. The loaded CPT was released only at the lower (acidic) pH normally found in a tumor environment but not in basic and neutral pH. GO-PDEA did not show practical toxicity to N2a cancer cells but the GO-PDEA-CPT complex exhibited high potency in killing N2a cancer cells in vitro. These results suggest that the GO-PDEA nanocargo carrier might be a promising material for site-specific anticancer drug delivery and controlled release.

Development and validation of a capillary electrophoresis method for the determination of codeine, diphenhydramine, ephedrine and noscapine in pharmaceuticals.

PubMed

Gomez, María R; Sombra, Lorena; Olsina, Roberto A; Martínez, Luis D; Silva, María F

2005-01-01

The present work describes a simple, accurate and rapid method for the separation and simultaneous determination of codeine, diphenhydramine, ephedrine and noscapine present in cough-cold syrup formulations by capillary zone electrophoresis. Factors affecting the separation were the buffer pH and concentration, applied voltage, and presence of additives. Separations were carried out in less than 10 min with a 20 mM sodium tetraborate buffer, pH 8.50. The carrier electrolyte gave baseline separation with good resolution, great reproducibility and accuracy. Calibration plots were linear over at least three orders of magnitude of analyte concentrations, the lower limits of detection being within the range 0.42-1.33 microg ml(-1). Detection was performed by UV absorbance at wavelengths of 205 and 250 nm. Quantification of the components in actual syrup formulations was calculated against the responses of freshly prepared external standard solutions. The method was validated and met all analysis requirements of quality assurance and quality control. The procedure was fast and reliable and commercial pharmaceuticals could be analyzed without prior sample clean-up procedure.

Behaviour of Zinc Complexes and Zinc Sulphide Nanoparticles Revealed by Using Screen Printed Electrodes and Spectrometry

PubMed Central

Nejdl, Lukas; Ruttkay-Nedecky, Branislav; Kudr, Jiří; Kremplova, Monika; Cernei, Natalia; Prasek, Jan; Konecna, Marie; Hubalek, Jaromir; Zitka, Ondrej; Kynicky, Jindrich; Kopel, Pavel; Kizek, Rene; Adam, Vojtech

2013-01-01

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl2, Zn(his)Cl2) and ZnS quantum dots (QDs) using printed electrodes. This method was chosen due to the simple (easy to use) instrumentation and variable setting of flows. Reduction signals of zinc under the strictly defined and controlled conditions (pH, temperature, flow rate, accumulation time and applied potential) were studied. We showed that the increasing concentration of the complexes (Zn(phen)(his)Cl2, Zn(his)Cl2) led to a decrease in the electrochemical signal and a significant shift of the potential to more positive values. The most likely explanation of this result is that zinc is strongly bound in the complex and its distribution on the electrode is very limited. Changing the pH from 3.5 to 5.5 resulted in a significant intensification of the Zn(II) reduction signal. The complexes were also characterized by UV/VIS spectrophotometry, chromatography, and ESI-QTOF mass spectrometry. PMID:24233071

Long-term effect of tobacco on unstimulated salivary pH.

PubMed

Grover, Neeraj; Sharma, Jyoti; Sengupta, Shamindra; Singh, Sanjeet; Singh, Nishant; Kaur, Harjeet

2016-01-01

The aim of this study was to analyze and compare the effects of tobacco on salivary pH between tobacco chewers, smokers and controls. A total of 60 subjects (males and females) aged 25-40 years, were divided equally into three groups: Tobacco smokers (Group A), chewers (Group B) and controls (Group C). Saliva of each subject was collected under resting condition. Salivary pH was determined using the specific salivary pH meter. The mean (±standard deviation) pH for Group A was 6.75 (±0.11), Group B was 6.5 (±0.29) and Group C was 7.00 (±0.28) after comparison. The significant results showed lower salivary pH in Groups A and B as compared to controls. Salivary pH was lowest in Group B compared to Group A and Group C. This study indicates that a lower (acidic) salivary pH was observed in tobacco users as compared with control. These alterations in pH due to the long-term effect of tobacco use can render oral mucosa vulnerable to various oral and dental diseases.

Morphological driven photocatalytic activity of ZnO nanostructures

NASA Astrophysics Data System (ADS)

Abbas, Khaldoon N.; Bidin, Noriah

2017-02-01

Using a simple combination of pulse laser ablation in liquid and hydrothermal (PLAL-H) approaches, we control the morphology of ZnO nanostructures (ZNSs) to determine the feasibility of their photocatalytic efficacy. These ZNSs are deposited on Si (100) substrates and two different morphologies are achieved. In this synergistic approach, PLAL synthesized NSs are used as a nutrient solution with different pH for further hydrothermal treatment at 110 °C under varying growth time (5, 30 and 60 min). Surface morphology, structure, composition, and optical characteristics of the prepared ZNSs are determined using FESEM, XRD, FTIR and Photoluminescence (PL) and UV-vis absorption measurements. The morphology revealed remarkable transformation from nanorods (NRs)/nanoflowers (NFs) (at pH 7.6) to nanoparticles (NPs)-like (at pH 10.5) structure. XRD patterns showed better polycrystallinity for NPs with enlarged band gap than NR/NF-like structures. Both PL and UV-vis spectral analysis of ZNPs exhibited higher surface area and deep level defects density dependent morphology, where the nutrient pH and growth time variation are found to play a significant role towards structural evolution. Furthermore, the photocatalytic activities of, such ZNSs are evaluated via sunlight driven photo-degradation of methylene blue (MB) dye. The photocatalytic efficiency of ZNPs is demonstrated to be much superior (97.4%) than ZNRs/ZNFs-like morphology (86%). Such enhanced photocatalytic activities of as-synthesized ZNPs is attributed to the synergism of the improved surface area and defects density, which is useful for promoting the adsorption of the MB dye and suppressed surface recombination of photo-generated charge carriers.

Monosodium glutamate for simple photometric iron analysis

NASA Astrophysics Data System (ADS)

Prasetyo, E.

2018-01-01

Simple photometric method for iron analysis using monosodium glutamate (MSG) was proposed. The method could be used as an alternative method, which was technically simple, economic, quantitative, readily available, scientifically sound and environmental friendly. Rapid reaction of iron (III) with glutamate in sodium chloride-hydrochloric acid buffer (pH 2) to form red-brown complex was served as a basis in the photometric determination, which obeyed the range of iron (III) concentration 1.6 - 80 µg/ml. This method could be applied to determine iron concentration in soil with satisfactory results (accuracy and precision) compared to other photometric and atomic absorption spectrometry results.

Diclofenac removal from water with ozone and activated carbon.

PubMed

Beltrán, Fernando J; Pocostales, Pablo; Alvarez, Pedro; Oropesa, Ana

2009-04-30

Diclofenac (DCF) has been treated in water with ozone in the presence of various activated carbons. Activated carbon-free ozonation or single ozonation leads to a complete degradation of DCF in less than 15 min while in the presence of activated carbons higher degradation rates of TOC and DCF are noticeably achieved. Among the activated carbons used, P110 Hydraffin was found the most suitable for the catalytic ozonation of DCF. The influence of pH was also investigated. In the case of the single ozonation the increasing pH slightly increases the TOC removal rate. This effect, however, was not so clear in the presence of activated carbons where the influence of the adsorption process must be considered. Ecotoxicity experiments were performed, pointing out that single ozonation reduces the toxicity of the contaminated water but catalytic ozonation improved those results. As far as kinetics is concerned, DCF is removed with ozone in a fast kinetic regime and activated carbon merely acts as a simple adsorbent. However, for TOC removal the ozonation kinetic regime becomes slow. In the absence of the adsorbent, the apparent rate constant of the mineralization process was determined at different pH values. On the other hand, determination of the rate constant of the catalytic reaction over the activated carbon was not possible due to the effect of mass transfer resistances that controlled the process rate at the conditions investigated.

Bromide-free TEMPO-mediated oxidation of primary alcohol groups in starch and methyl alpha-D-glucopyranoside.

PubMed

Bragd, P L; Besemer, A C; van Bekkum, H

2000-09-22

TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)-mediated oxidation of potato starch and methyl alpha-D-glucopyranoside (MGP) was performed in the absence of sodium bromide (NaBr) as co-catalyst, solely using sodium hypochlorite (NaOCl) as the primary oxidant. The low reaction rate associated with a bromide-free process was increased by performing the oxidation at increased temperatures. The reaction proceeded stoichiometrically and with high selectivity and with only minor depolymerisation, provided that temperature and pH were kept < or = 20 degrees C and < 9.0, respectively. At 20 degrees C and pH 8.5, the reaction rate was comparable to that of a corresponding oxidation catalysed by NaBr at 2 degrees C. Consequently, this is a simple approach to raise the TEMPO/NaOCl reaction rate under bromide-free conditions while still maintaining good product properties. At higher oxidation temperatures (> or = 25 degrees C) and under more alkaline conditions (pH > or = 9.0) degradation of the starch skeleton occurred. Simultaneously, side-reactions of the nitrosonium ion lowered the yield of the oxidation. Despite the absence of the NaBr catalyst, the reaction rate-controlling step was found to be the oxidation of the primary hydroxyl groups with the nitrosonium ion. The reaction was first-order in MGP and in TEMPO.

Influence of mineral colloids and humic substances on uranium(VI) transport in water-saturated geologic porous media

NASA Astrophysics Data System (ADS)

Wang, Qing; Cheng, Tao; Wu, Yang

2014-12-01

Mineral colloids and humic substances often co-exist in subsurface environment and substantially influence uranium (U) transport. However, the combined effects of mineral colloids and humic substances on U transport are not clear. This study is aimed at quantifying U transport and elucidating geochemical processes that control U transport when both mineral colloids and humic acid (HA) are present. U-spiked solutions/suspensions were injected into water-saturated sand columns, and U and colloid concentrations in column effluent were monitored. We found that HA promoted U transport via (i) formation of aqueous U-HA complexes, and (ii) competition against aqueous U for surface sites on transport media. Illite colloids had no influence on U transport at pH 5 in the absence of HA due to low mobility of the colloids. At pH 9, U desorbed from mobile illite and the presence of illite decreased U transport. At pH 5, high U transport occurred when both illite colloids and HA were present, which was attributed to enhanced U adsorption to illite colloids via formation of ternary illite-HA-U surface complexes, and enhanced illite transport due to HA attachment to illite and transport media. This study demonstrates that the combined effects of mineral colloids and HA on contaminant transport is different from simple addition of the individual effect.

Isosteric Substitution of 4H-1,2,4-Triazole by 1H-1,2,3-Triazole in Isophthalic Derivative Enabled Hydrogel Formation for Controlled Drug Delivery.

PubMed

Häring, Marleen; Rodríguez-López, Julio; Grijalvo, Santiago; Tautz, Markus; Eritja, Ramón; Martín, Víctor S; Díaz Díaz, David

2018-02-20

In this work, we demonstrated that the simple substitution of the 1,2,4-triazole moiety in 5-(4H-1,2,4-triazol-4-yl)isophthalic acid (5-TIA) by the 1H-1,2,3-triazol-5-yl unit enables the preparation of a hydrogelator (click-TIA). In sharp contrast to 5-TIA, its isostere click-TIA undergoes self-assembly in water upon sonication, leading to the formation of stable supramolecular viscoelastic hydrogels with a critical gelation concentration of 6 g/L. Hydrogels made of click-TIA as well as hybrid hydrogels made of the mixture click-TIA + 5-TIA (molar ratio 1:0.2) were used to compare different properties of the materials (i.e., rheological properties, thermal properties, mechanical stability, morphology). In terms of toxicity, neither click-TIA nor 5-TIA showed cytotoxic effects on cellular viability of HeLa cells up to 2.3 × 10 -3 g/L when compared to untreated cells incubated with DMSO. Furthermore, the hydrogels were used for the encapsulation and in vitro controlled release of oxytetracycline that followed first-order kinetics. For the hydrogel made of click-TIA, a maximum drug release of ∼60% was reached after ∼8 h within a pH range between 6.5 and 10. However, the release rate was reduced to approximately half of its value at pH values between 1.2 and 5.0, whereas the use of hybrid hydrogels made of click-TIA + 5-TIA allowed to reduce the original rate at pH ≤ 6.5.

Non-acid gastro-oesophageal reflux is associated with squamous cell carcinoma of the oesophagus.

PubMed

Kgomo, Mpho; Mokoena, Taole R; Ker, James A

2017-01-01

Squamous cell carcinoma of the oesophagus is a common cancer among South Africans. Due to the absence of effective screening and surveillance programme for early detection and late presentation, squamous cell carcinoma of the oesophagus is usually diagnosed at an advanced stage or when metastasis has already occurred. The 5-year survival is often quoted at 5%-10%, which is poor. To determine the association between oesophageal squamous cell carcinoma (OSCC) and non-acid gastro-oesophageal reflux disease. Study design: A cross-sectional case-control analytical study of patients referred to the Gastroenterology Division of Steve Biko Academic Hospital in Pretoria, South Africa. All patients had combined multichannel impedance and pH studies done and interpreted after upper gastroscopy using the American College of Gastroenterology guidelines by two clinicians. Thirty-two patients with OSCC were recruited: non-acid reflux was found in 23 patients (73%), acid reflux in 2 patients (6%) and 7 patients (22%) had normal multichannel impedance and pH studies.Forty-nine patients matched by age, gender and race were recruited as a control group. Non-acid reflux was found in 11 patients (22%), acid reflux in 31 patients (63%) and 7 patients (14%) had normal multichannel impedance and pH monitoring study. The significance of the association between non-acid reflux and OSCC was tested using χ 2 , and simple logistic regression was used to adjust for the effects of potential confounders.The OR of developing OSCC in patients with non-acid gastro-oesophageal reflux was 8.8 (95% CI 3.2 to 24.5, P<0.0001) in this South African group.Alcohol and smoking had no effect on these results.

Non-acid gastro-oesophageal reflux is associated with squamous cell carcinoma of the oesophagus

PubMed Central

Kgomo, Mpho; Mokoena, Taole R; Ker, James A

2017-01-01

Introduction Squamous cell carcinoma of the oesophagus is a common cancer among South Africans. Due to the absence of effective screening and surveillance programme for early detection and late presentation, squamous cell carcinoma of the oesophagus is usually diagnosed at an advanced stage or when metastasis has already occurred. The 5-year survival is often quoted at 5%–10%, which is poor. Objectives To determine the association between oesophageal squamous cell carcinoma (OSCC) and non-acid gastro-oesophageal reflux disease. Methods Study design A cross-sectional case–control analytical study of patients referred to the Gastroenterology Division of Steve Biko Academic Hospital in Pretoria, South Africa. All patients had combined multichannel impedance and pH studies done and interpreted after upper gastroscopy using the American College of Gastroenterology guidelines by two clinicians. Results Thirty-two patients with OSCC were recruited: non-acid reflux was found in 23 patients (73%), acid reflux in 2 patients (6%) and 7 patients (22%) had normal multichannel impedance and pH studies. Forty-nine patients matched by age, gender and race were recruited as a control group. Non-acid reflux was found in 11 patients (22%), acid reflux in 31 patients (63%) and 7 patients (14%) had normal multichannel impedance and pH monitoring study. Conclusion The significance of the association between non-acid reflux and OSCC was tested using χ2, and simple logistic regression was used to adjust for the effects of potential confounders. The OR of developing OSCC in patients with non-acid gastro-oesophageal reflux was 8.8 (95% CI 3.2 to 24.5, P<0.0001) in this South African group. Alcohol and smoking had no effect on these results. PMID:29177066

Polymer Nanosheet Containing Star-Like Copolymers: A Novel Scalable Controlled Release System.

PubMed

Cao, Peng-Fei; de Leon, Al; Rong, Lihan; Yin, Ke-Zhen; Abenojar, Eric C; Su, Zhe; Tiu, Brylee David B; Exner, Agata A; Baer, Eric; Advincula, Rigoberto C

2018-04-26

Poly(ε-caprolactone) (PCL)-based nanomaterials, such as nanoparticles and liposomes, have exhibited great potential as controlled release systems, but the difficulties in large-scale fabrication limit their practical applications. Among the various methods being developed to fabricate polymer nanosheets (PNSs) for different applications, such as Langmuir-Blodgett technique and layer-by-layer assembly, are very effort consuming, and only a few PNSs can be obtained. In this paper, poly(ε-caprolactone)-based PNSs with adjustable thickness are obtained in large quantity by simple water exposure of multilayer polymer films, which are fabricated via a layer multiplying coextrusion method. The PNS is also demonstrated as a novel controlled guest release system, in which release kinetics are adjustable by the nanosheet thickness, pH values of the media, and the presence of protecting layers. Theoretical simulations, including Korsmeyer-Peppas model and Finite-element analysis, are also employed to discern the observed guest-release mechanisms. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controllable biosynthesis of gold nanoparticles from a Eucommia ulmoides bark aqueous extract

NASA Astrophysics Data System (ADS)

Guo, Mingxia; Li, Wei; Yang, Feng; Liu, Huihong

2015-05-01

The present work reports the green synthesis of gold nanoparticles (AuNPs) by water extract of Eucommia ulmoides (E. ulmoides) bark. The effects of various parameters such as the concentration of reactants, pH of the reaction mixture, temperature and the time of incubation were explored to the controlled formation of gold nanoparticles. The characterization through high resolution-transmission electron microscopic (HRTEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) infer that the as-synthesized AuNPs were spherical in shape with a face cubic crystal (FCC) structure. The results from zeta potential and dynamic light scattering (DLS) suggest the good stability and narrow size distribution of the AuNPs. This method for synthesis of AuNPs is simple, economic, nontoxic and efficient. The as-synthesized AuNPs show excellent catalytic activity for the catalytic reducing decoloration of model compounds of azo-dye: reactive yellow 179 and Congo red.

Evaluation of pH monitoring as a method of processor control.

PubMed

Stears, J G; Gray, J E; Winkler, N T

1979-01-01

Sensitometry and pH values of the developer solution were compared in controlled over-replenishment, developer depletion, fixer contamination experiments, and on a daily quality control basis. The purpose of these comparisons was to evaluate the potential of pH monitoring as a method of processor control, or a supplement to sensitometry as a method of quality control. Reasonable correlation was found between pH values and film density in two of the three experiments but little or no correlation was found in the third experiment and on a day-to-day basis. The conclusion drawn from these comparisons is that pH monitoring has several limitations which render it unsuitable as a method of daily processor quality control as either a primary or supplementary technique. Sensitometry takes into account all the variables encountered in film processing and is the clear method of choice for processor quality control.

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.

A Simple Method to Reduce both Lactic Acid and Ammonium Production in Industrial Animal Cell Culture

PubMed Central

Freund, Nathaniel W.; Croughan, Matthew S.

2018-01-01

Fed-batch animal cell culture is the most common method for commercial production of recombinant proteins. However, higher cell densities in these platforms are still limited due to factors such as excessive ammonium production, lactic acid production, nutrient limitation, and/or hyperosmotic stress related to nutrient feeds and base additions to control pH. To partly overcome these factors, we investigated a simple method to reduce both ammonium and lactic acid production—termed Lactate Supplementation and Adaptation (LSA) technology—through the use of CHO cells adapted to a lactate-supplemented medium. Using this simple method, we achieved a reduction of nearly 100% in lactic acid production with a simultaneous 50% reduction in ammonium production in batch shaker flasks cultures. In subsequent fed-batch bioreactor cultures, lactic acid production and base addition were both reduced eight-fold. Viable cell densities of 35 million cells per mL and integral viable cell days of 273 million cell-days per mL were achieved, both among the highest currently reported for a fed-batch animal cell culture. Investigating the benefits of LSA technology in animal cell culture is worthy of further consideration and may lead to process conditions more favorable for advanced industrial applications. PMID:29382079

A Simple Method to Reduce both Lactic Acid and Ammonium Production in Industrial Animal Cell Culture.

PubMed

Freund, Nathaniel W; Croughan, Matthew S

2018-01-28

Fed-batch animal cell culture is the most common method for commercial production of recombinant proteins. However, higher cell densities in these platforms are still limited due to factors such as excessive ammonium production, lactic acid production, nutrient limitation, and/or hyperosmotic stress related to nutrient feeds and base additions to control pH. To partly overcome these factors, we investigated a simple method to reduce both ammonium and lactic acid production-termed Lactate Supplementation and Adaptation (LSA) technology-through the use of CHO cells adapted to a lactate-supplemented medium. Using this simple method, we achieved a reduction of nearly 100% in lactic acid production with a simultaneous 50% reduction in ammonium production in batch shaker flasks cultures. In subsequent fed-batch bioreactor cultures, lactic acid production and base addition were both reduced eight-fold. Viable cell densities of 35 million cells per mL and integral viable cell days of 273 million cell-days per mL were achieved, both among the highest currently reported for a fed-batch animal cell culture. Investigating the benefits of LSA technology in animal cell culture is worthy of further consideration and may lead to process conditions more favorable for advanced industrial applications.

Fast and Simple Discriminative Analysis of Anthocyanins-Containing Berries Using LC/MS Spectral Data.

PubMed

Yang, Heejung; Kim, Hyun Woo; Kwon, Yong Soo; Kim, Ho Kyong; Sung, Sang Hyun

2017-09-01

Anthocyanins are potent antioxidant agents that protect against many degenerative diseases; however, they are unstable because they are vulnerable to external stimuli including temperature, pH and light. This vulnerability hinders the quality control of anthocyanin-containing berries using classical high-performance liquid chromatography (HPLC) analytical methodologies based on UV or MS chromatograms. To develop an alternative approach for the quality assessment and discrimination of anthocyanin-containing berries, we used MS spectral data acquired in a short analytical time rather than UV or MS chromatograms. Mixtures of anthocyanins were separated from other components in a short gradient time (5 min) due to their higher polarity, and the representative MS spectrum was acquired from the MS chromatogram corresponding to the mixture of anthocyanins. The chemometric data from the representative MS spectra contained reliable information for the identification and relative quantification of anthocyanins in berries with good precision and accuracy. This fast and simple methodology, which consists of a simple sample preparation method and short gradient analysis, could be applied to reliably discriminate the species and geographical origins of different anthocyanin-containing berries. These features make the technique useful for the food industry. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Biodiesel transesterification kinetics monitored by pH measurement.

PubMed

Clark, William M; Medeiros, Nicholas J; Boyd, Donal J; Snell, Jared R

2013-05-01

Quantification of a pH change that was observed over the course of the transesterification reaction that converts vegetable oil to biodiesel may provide a simple method to monitor the reaction. Transesterification of canola oil at 6:1 methanol to oil ratio with 0.5 wt.% KOH as catalyst was studied at 25, 35, and 45 °C. Reaction conversion was correlated to pH measurements and the results were shown to be in agreement with an independent measure of conversion using an enzymatic assay for glycerol. Rate constants obtained from these measurements are consistent with those in the literature. The measured pH change appears to be related to dilution of OH(-) ions as the oil is converted to products rather than to depletion of OH(-) due to reaction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Variation in the pH of faeces in disease

PubMed Central

Madanagopalan, N.; Nadar, S. Arumugan; Subramaniam, R.

1970-01-01

Although it is highly unlikely that a disease can be definitively diagnosed from a study of the pH of the faeces alone, the present study has helped to dispel the past belief that the pH of faeces in acute amoebic dysentery is more likely to be acidic. Culture for other pathogenic organisms has not been done in the present series of cases, but the chances of the coincidence of bacillary dysentery in this group would probably not have been significant. Further, in the past a simple litmus paper test was suggested to differentiate an amoebic dysentery from a bacillary dysentery, a procedure which can no longer hold good. PMID:5428858

eQuilibrator--the biochemical thermodynamics calculator.

PubMed

Flamholz, Avi; Noor, Elad; Bar-Even, Arren; Milo, Ron

2012-01-01

The laws of thermodynamics constrain the action of biochemical systems. However, thermodynamic data on biochemical compounds can be difficult to find and is cumbersome to perform calculations with manually. Even simple thermodynamic questions like 'how much Gibbs energy is released by ATP hydrolysis at pH 5?' are complicated excessively by the search for accurate data. To address this problem, eQuilibrator couples a comprehensive and accurate database of thermodynamic properties of biochemical compounds and reactions with a simple and powerful online search and calculation interface. The web interface to eQuilibrator (http://equilibrator.weizmann.ac.il) enables easy calculation of Gibbs energies of compounds and reactions given arbitrary pH, ionic strength and metabolite concentrations. The eQuilibrator code is open-source and all thermodynamic source data are freely downloadable in standard formats. Here we describe the database characteristics and implementation and demonstrate its use.

eQuilibrator—the biochemical thermodynamics calculator

PubMed Central

Flamholz, Avi; Noor, Elad; Bar-Even, Arren; Milo, Ron

2012-01-01

The laws of thermodynamics constrain the action of biochemical systems. However, thermodynamic data on biochemical compounds can be difficult to find and is cumbersome to perform calculations with manually. Even simple thermodynamic questions like ‘how much Gibbs energy is released by ATP hydrolysis at pH 5?’ are complicated excessively by the search for accurate data. To address this problem, eQuilibrator couples a comprehensive and accurate database of thermodynamic properties of biochemical compounds and reactions with a simple and powerful online search and calculation interface. The web interface to eQuilibrator (http://equilibrator.weizmann.ac.il) enables easy calculation of Gibbs energies of compounds and reactions given arbitrary pH, ionic strength and metabolite concentrations. The eQuilibrator code is open-source and all thermodynamic source data are freely downloadable in standard formats. Here we describe the database characteristics and implementation and demonstrate its use. PMID:22064852

A simple differential pulse polarographic method for the determination of thymoquinone in black seed oil.

PubMed

Michelitsch, Astrid; Rittmannsberger, Anna

2003-01-01

A reliable and simple differential pulse polarographic method is described for the determination of thymoquinone in black seed oil. The polarographic behaviour of thymoquinone was examined in various buffer systems over the pH range 5.0-10.0. Thymoquinone is reduced in a single, reversible peak at the dropping mercury electrode. The differential pulse polarogram showed a distinct peak in Sörensen buffer:methanol (3:7, v/v; pH 8.5) at a peak potential of -0.095 V (vs. silver/silver chloride electrode), and a plot of peak height against concentration was found to be linear over the range 0.2-15.0 microg/mL (R = 0.9998). The limit of detection was calculated to be 0.054 microg/mL. The polarographic method has been applied to determine thymoquinone in two black seed oil preparations available on the Austrian pharmaceutical market.

Development of a Simple Method for Concentrating Enteroviruses from Oysters

PubMed Central

Sobsey, Mark D.; Wallis, Craig; Melnick, Joseph L.

1975-01-01

The development of a simple method for concentrating enteroviruses from oysters is described. In this method viruses in homogenized oyster tissues are efficiently adsorbed to oyster solids at pH 5.5 and low salt concentration. After low-speed centrifugation, the supernatant is discarded and viruses are eluted from the sedimented oyster solids by resuspending them in pH 3.5 glycine-buffered saline. The solids are then removed by low-speed centrifugation, and the virus-containing supernatant is filtered through a 0.2-μm porosity filter to remove bacteria and other small particulates without removing viruses. The virus-containing filtrate is then concentrated to a volume of a few milliliters by ultrafiltration, and the concentrate obtained is inoculated directly into cell cultures for virus assay. When tested with pools of oysters experimentally contaminated with small amounts of different enteroviruses, virus recovery efficiency averaged 63%. PMID:234154

Development of a simple method for concentrating enteroviruses from oysters.

PubMed

Sobsey, M D; Wallis, C; Melnick, J L

1975-01-01

The development of a simple method for concentrating enteroviruses from oysters is described. In this method viruses in homogenized oyster tissues are efficiently absorbed to oyster solids at pH 5.5 and low salt concentration. After low-speed centrifugation, the supernatant is discarded and viruses are eluted from the sedimented oyster solids by resuspending them in pH 3.5 glycine-buffered saline. The solids are then removed by low-speed centrifugation, and the virus-containing supernatant is filtered through a 0.2-micronm porosity filter to remove bacteria and other small particulates without removing viruses. The virus-containing filtrate is then concentrated to a volume of a few milliliters by ultrafiltration, and the concentrate obtained is inoculated directly into cell cultures for virus assay. When tested with pools of oysters experimentally contaminated with small amounts of different enteroviruses, virus recovery efficiency averaged 63%.

Simple Response Surface Methodology: Investigation on Advance Photocatalytic Oxidation of 4-Chlorophenoxyacetic Acid Using UV-Active ZnO Photocatalyst.

PubMed

Lee, Kian Mun; Hamid, Sharifah Bee Abd

2015-01-19

The performance of advance photocatalytic degradation of 4-chlorophenoxyacetic acid (4-CPA) strongly depends on photocatalyst dosage, initial concentration and initial pH. In the present study, a simple response surface methodology (RSM) was applied to investigate the interaction between these three independent factors. Thus, the photocatalytic degradation of 4-CPA in aqueous medium assisted by ultraviolet-active ZnO photocatalyst was systematically investigated. This study aims to determine the optimum processing parameters to maximize 4-CPA degradation. Based on the results obtained, it was found that a maximum of 91% of 4-CPA was successfully degraded under optimal conditions (0.02 g ZnO dosage, 20.00 mg/L of 4-CPA and pH 7.71). All the experimental data showed good agreement with the predicted results obtained from statistical analysis.

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.

A mathematical model for the generation and control of a pH gradient in an immobilized enzyme system involving acid generation.

PubMed

Chen, G; Fournier, R L; Varanasi, S

1998-02-20

An optimal pH control technique has been developed for multistep enzymatic synthesis reactions where the optimal pH differs by several units for each step. This technique separates an acidic environment from a basic environment by the hydrolysis of urea within a thin layer of immobilized urease. With this technique, a two-step enzymatic reaction can take place simultaneously, in proximity to each other, and at their respective optimal pH. Because a reaction system involving an acid generation represents a more challenging test of this pH control technique, a number of factors that affect the generation of such a pH gradient are considered in this study. The mathematical model proposed is based on several simplifying assumptions and represents a first attempt to provide an analysis of this complex problem. The results show that, by choosing appropriate parameters, the pH control technique still can generate the desired pH gradient even if there is an acid-generating reaction in the system. Copyright 1998 John Wiley & Sons, Inc.

Colforsin-induced vasodilation in chronic hypoxic pulmonary hypertension in rats.

PubMed

Yokochi, Ayumu; Itoh, Hiroo; Maruyama, Junko; Zhang, Erquan; Jiang, Baohua; Mitani, Yoshihide; Hamada, Chikuma; Maruyama, Kazuo

2010-06-01

Colforsin, a water-soluble forskolin derivative, directly activates adenylate cyclase and thereby increases the 3',5'-cyclic adenosine monophosphate (cAMP) level in vascular smooth muscle cells. In this study, we investigated the vasodilatory action of colforsin on structurally remodeled pulmonary arteries from rats with pulmonary hypertension (PH). A total of 32 rats were subjected to hypobaric hypoxia (380 mmHg, 10% oxygen) for 10 days to induce chronic hypoxic PH, while 39 rats were kept in room air. Changes in isometric force were recorded in endothelium-intact (+E) and -denuded (-E) pulmonary arteries from the PH and control (non-PH) rats. Colforsin-induced vasodilation was impaired in both +E and -E arteries from PH rats compared with their respective controls. Endothelial removal did not influence colforsin-induced vasodilation in the arteries from control rats, but attenuated it in arteries from PH rats. The inhibition of nitric oxide (NO) synthase did not influence colforsin-induced vasodilation in +E arteries from controls, but attenuated it in +E arteries from PH rats, shifting its concentration-response curve closer to that of -E arteries from PH rats. Vasodilation induced by 8-bromo-cAMP (a cell-permeable cAMP analog) was also impaired in -E arteries from PH rats, but not in +E arteries from PH rats, compared with their respective controls. cAMP-mediated vasodilatory responses without beta-adrenergic receptor activation are impaired in structurally remodeled pulmonary arteries from PH rats. In these arteries, endothelial cells presumably play a compensatory role against the impaired cAMP-mediated vasodilatory response by releasing NO (and thereby attenuating the impairment). The results suggest that colforsin could be effective in the treatment of PH.

Comparison of arterial and venous blood gases and the effects of analysis delay and air contamination on arterial samples in patients with chronic obstructive pulmonary disease and healthy controls.

PubMed

O'Connor, T M; Barry, P J; Jahangir, A; Finn, C; Buckley, B M; El-Gammal, A

2011-01-01

Arterial blood gases (ABGs) are often sampled incorrectly, leading to a 'mixed' or venous sample. Delays in analysis and air contamination are common. We measured the effects of these errors in patients with chronic obstructive pulmonary disease (COPD) exacerbations and controls. Arterial and venous samples were analyzed from 30 patients with COPD exacerbation and 30 controls. Venous samples were analysed immediately and arterial samples separated into non-air-contaminated and air-contaminated specimens and analysed at 0, 30, 60, 90 and 180 min. Mean venous pH was 7.371 and arterial pH was 7.407 (p < 0.0001). There was a correlation between venous and arterial pH (r = 0.5347, p < 0.0001). The regression equation to predict arterial pH was: arterial pH = 4.2289 + 0.43113 · venous pH. There were no clinically significant differences in arterial PO₂ associated with analysis delay. A statistically significant decline in pH was detected at 30 min in patients with COPD exacerbation (p = 0.0042) and 90 min in controls (p < 0.0001). A clinically significant decline in pH emerged at 73 min in patients with COPD exacerbation and 87 min in controls. Air contamination was associated with a clinically significant increase in PO₂ in all samples, including those that were immediately analyzed. Arterial and venous pH differ significantly. Venous pH cannot accurately replace arterial pH. Temporal delays in ABG analysis result in a significant decline in measured pH. ABGs should be analysed within 30 min. Air contamination leads to an immediate increase in measured PO₂, indicating that air-contaminated ABGs should be discarded. Copyright © 2010 S. Karger AG, Basel.

Sol gel synthesis and pH effect on the luminescent and structural properties of YPO4: Pr3+ nanophosphors

NASA Astrophysics Data System (ADS)

Kahouadji, B.; Guerbous, L.; Boukerika, A.; Dolić, Slobodan D.; Jovanović, Dragana J.; Dramićanin, Miroslav D.

2017-08-01

Pr3+ -doped YPO4 nanophosphors prepared by simple sol gel method with different pH values (2, 4, 7 and 11) were obtained. The nanopowders samples were characterized by X-ray diffraction (XRD), room temperature steady and time resolved photoluminescence spectroscopy. The thorough study of pH influence on particle's structure and luminescence of YPO4: 1 at. Pr3+ is presented. It was found that the grain size of samples increases with increases in pH value and obtained particles crystallize in a tetragonal phase with xenotime structure. Under 4f5d excitation (230 nm), all emission spectra show the inter-configurational 4f2→4f5d and under 3P2 excitation (449 nm), only the intra-configurational 1D2→3H4 red emission transition between 580 nm and 620 nm are observed. The highest luminescent intensity was obtained for samples prepared at pH = 4. Furthermore, it was found that the pH of solution has no effect of 1D2 lifetime.

Analysis of pharmaceutical biodegradation of WWTP sludge using composting and identification of certain microorganisms involved in the process.

PubMed

Iranzo, María; Gamón, Miguel; Boluda, Rafael; Mormeneo, Salvador

2018-06-04

Pharmaceuticals (PhCs) are organic contaminants that have been detected in wastewater, surface water, and soils throughout the world. The presence of 10 commonly used PhCs in Spain (azithromycin, benzylpenicillin, citalopram, fluconazole, fluoxetine, ibuprofen, irbesartan, olanzapine, telmisartan, and venlafaxine) was analysed at four wastewater treatment plants, and the changes in their concentrations during treatment were assessed. Although certain some PhCs were degraded in the treated water, their presence in sewage sludge increased in all cases. The sewage sludge was composted using rice straw to degrade the PhCs, and the composting efficiency was modified by changes in the relative C/N ratio of the composting blend. Using a simple microbiological culture process for enrichment, 11 different strains of microorganisms that degraded specific PhCs were identified. Ibuprofen and azithromycin were metabolized by one and four strains, respectively, and both PhCs were used as a carbon source; in addition, six strains used irbesartan as a nitrogen source. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of pH on the Transformation of a New Readymix Formulation of the Herbicides Bispyribac Sodium and Metamifop in Water.

PubMed

Saha, Suman; Majumder, Sambrita; Das, Sushovan; Das, Tapan Kumar; Bhattacharyya, Anjan; Roy, Sankhajit

2018-04-01

A laboratory experiment was conducted to investigate the effect of pH on the persistence and the dissipation of the new readymix formulation of bispyribac sodium and metamifop. The experiment was conducted in water of three different pH viz. 4.0, 7.0 and 9.2. The spiking level of both the compounds in water was 1.0 and 2.0 µg/mL. The residues were extracted by a simple, quick and reliable method and quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS). The method was justified based on the recovery study, which was > 85%. The dissipation of both compounds followed first order kinetics. The half-life values ranged between 19.86-36.29 and 9.92-19.69 days for bispyribac sodium and metamifop, respectively. The pH of water has a prominent effect on degradation of both the compounds. The rate of dissipation of both the compounds was highest in water of acidic pH followed by neutral and alkaline pH.

Low pH affects survival, growth, size distribution, and carapace quality of the postlarvae and early juveniles of the freshwater prawn Macrobrachium rosenbergii de Man

NASA Astrophysics Data System (ADS)

Kawamura, Gunzo; Bagarinao, Teodora; Yong, Annita Seok Kian; Chen, Chiau Yu; Noor, Siti Norasidah Mat; Lim, Leong Seng

2015-06-01

Acidification of rain water caused by air pollutants is now recognized as a serious threat to aquatic ecosystems. We examined the effects of low pH (control pH 7.5, pH 6, pH 5, pH 4) on the survival, growth, and shell quality of Macrobrachium rosenbergii postlarvae and early juveniles in the laboratory. Hatcheryproduced postlarvae (PL 5) were stocked at 250 PL per aquarium, acclimated over 7 d to experimental pH adjusted with hydrochloric acid, and reared for 30 d. Dead specimens were removed and counted twice a day. After 27 d rearing, all specimens were measured for total length and body weight. Carapace quality was assessed by spectrophotometry. Survival of juveniles was highest at pH 6 (binomial 95% confidence interval 79 - 89%) followed by control pH 7.5 (56 - 68%) and pH 5 (50 - 60%) and was lowest for unmetamorphosed postlarvae and juveniles at pH 4 (43 - 49%). The final median total length and body weight of juveniles were similar at control pH 7.5 (18.2 TL, 50.2 mg BW) and pH 6 (17.7 mm TL, 45.0 mg BW) but significantly less at pH 5 (16.7 mm TL, 38.2 mg BW); at pH 4, the postlarvae did not metamorphose and measured only 9.8 mm TL, 29.3 mg BW. Length frequency distribution showed homogeneous growth at pH 6, positive skew at control pH 7.5 and pH 5, and extreme heterogeneity at pH 4. The carapace showed different transmittance spectra and lower total transmittance (i.e. thicker carapace) in juveniles at pH 7.5, pH 6, and pH 5 than in unmetamorphosed postlarvae and juveniles with thinner carapace at pH 4. Thus, survival, growth, size distribution, and carapace quality of M. rosenbergii postlarvae and early juveniles were negatively affected by pH 5 and especially pH 4. The thinner carapace of the survivors at pH 4 was mostly due to their small size and failure to metamorphose. Natural waters affected by acid rain could decimate M. rosenbergii populations in the wild.

The Effects of Direct Oxygen Supply During Static Cold Preservation of Rat Livers: An Experimental Study.

PubMed

Zumrutdal, Emin; Karateke, Faruk; Eser, Pınar Eylem; Turan, Umit; Ozyazici, Sefa; Sozutek, Alper; Gulkaya, Mustafa; Kunt, Mevlut

2016-12-01

We aimed to determine the biochemical and histopathologic effects of direct oxygen supply to the preservation fluid of static cold storage system with a simple method on rat livers. Sixteen rats were randomly divided into 2 groups: the control group, which contained Ringer's lactate as preservation fluid; and the oxygen group, which contained oxygen and Ringer's lactate for preservation. Each liver was placed in a bag containing 50 mL Ringer's lactate and placed in ice-filled storage containers. One hundred percent oxygen supplies were given via a simple, inexpensive system created in our laboratory, to the livers in oxygen group. We obtained samples for histopathologic evaluation in the 12th hour. In addition, 3 mL of preservation fluid was subjected to biochemical analysis at 0, sixth, and twelfth hours. Aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pH levels were measured from the preservation fluid. In oxygen-supplemented group, the acceleration speed of increase in alanine aminotransferase and lactate dehydrogenase levels at sixth hour and lactate dehydrogenase, alanine aminotransferase, and lactate dehydrogenase levels at 12th hour were statistically significantly reduced. In histopathologic examination, all parameters except ballooning were statistically significantly better in the oxygen-supplemented group. This simple system for oxygenation of liver tissues during static cold storage was shown to be effective with good results in biochemical and histopathologic assessments. Because this is a simple, inexpensive, and easily available method, larger studies are warranted to evaluate its effects (especially in humans).

Strategy for pH control and pH feedback-controlled substrate feeding for high-level production of L-tryptophan by Escherichia coli.

PubMed

Cheng, Li-Kun; Wang, Jian; Xu, Qing-Yang; Zhao, Chun-Guang; Shen, Zhi-Qiang; Xie, Xi-Xian; Chen, Ning

2013-05-01

Optimum production of L-tryptophan by Escherichia coli depends on pH. Here, we established conditions for optimizing the production of L-tryptophan. The optimum pH range was 6.5-7.2, and pH was controlled using a three-stage strategy [pH 6.5 (0-12 h), pH 6.8 (12-24 h), and pH 7.2 (24-38 h)]. Specifically, ammonium hydroxide was used to adjust pH during the initial 24 h, and potassium hydroxide and ammonium hydroxide (1:2, v/v) were used to adjust pH during 24-38 h. Under these conditions, NH4 (+) and K(+) concentrations were kept below the threshold for inhibiting L-tryptophan production. Optimization was also accomplished using ratios (v/v) of glucose to alkali solutions equal to 4:1 (5-24 h) and 6:1 (24-38 h). The concentration of glucose and the pH were controlled by adjusting the pH automatically. Applying a pH-feedback feeding method, the steady-state concentration of glucose was maintained at approximately 0.2 ± 0.02 g/l, and acetic acid accumulated to a concentration of 1.15 ± 0.03 g/l, and the plasmid stability was 98 ± 0.5 %. The final, optimized concentration of L-tryptophan was 43.65 ± 0.29 g/l from 52.43 ± 0.38 g/l dry cell weight.

A NBD-based simple but effective fluorescent pH probe for imaging of lysosomes in living cells.

PubMed

Cao, Xiang-Jian; Chen, Li-Na; Zhang, Xuan; Liu, Jin-Ting; Chen, Ming-Yu; Wu, Qiu-Rong; Miao, Jun-Ying; Zhao, Bao-Xiang

2016-05-12

NBDlyso with lysosome-locating morpholine moiety has been developed as a high selective and sensitive fluorescent pH probe. This probe can respond to acidic pH (2.0-7.0) in a short time (less than 1 min) and not almost change after continuously illuminated for an extended period by ultraviolet light. The fluorescence intensity of NBDlyso enhanced 100-fold in acidic solution, with very good linear relationship (R(2) = 0.996). The pKa of probe NBDlyso is 4.10. Therefore, NBDlyso was used to detect lysosomal pH changes successfully. Besides, X-ray crystallography was used to verify the structure of NBDlyso, and the recognition mechanism involving photo-induced electron transfer was interpreted theoretically by means of DFT and TDDFT calculations skillfully when NBDlyso comes into play under the acidic condition. This probe showed good ability to sense pH change in living cell image. Copyright © 2016 Elsevier B.V. All rights reserved.

Improving clarity and stability of skim milk powder dispersions by dissociation of casein micelles at pH 11.0 and acidification with citric acid.

PubMed

Pan, Kang; Zhong, Qixin

2013-09-25

Casein micelles in milk cause turbidity and have poor stability at acidic conditions. In this study, skim milk powder dispersions were alkalized to pH 10.0 or 11.0, corresponding to reduced particle mass. In the following acidification with hydrochloric or citric acid, the re-formation of casein particles was observed. The combination of treatment at pH 11.0 and acidification with citric acid resulted in dispersions with the lowest turbidity and smallest particles, which enabled translucent dispersions at pH 5.5-7.0, corresponding to discrete nanoparticles. The concentration of ionic calcium was lower when acidified with citric acid than hydrochloric acid, corresponding to smaller particles with less negative zeta potential. The pH 11.0 treatment followed by acidification with citric acid also resulted in smaller particles than the simple chelating effects (directly implementing sodium citrate). The produced casein nanoparticles with reduced dimensions can be used for beverage and other novel applications.

Suitability Screening Test for Marine Corps Air Traffic Controllers Phase 2

DTIC Science & Technology

2013-06-10

Karen M. Walker, Ph.D. William L. Farmer, Ph.D. Rebecca C. Roberts, MS Navy Personnel Research, Studies, and Technology NPRST-TR-13-2...June 2013 Suitability Screening Test for Marine Corps Air Traffic Controllers Phase II Karen M. Walker, Ph.D. William L. Farmer, Ph.D. Rebecca...C. Roberts, MS Navy Personnel Research, Studies, and Technology Reviewed by Tanja Blackstone , Ph.D. Approved and released by D. M. Cashbaugh

Suitability Screening Test for Marine Corps Air Traffic Controllers. Phase 2

DTIC Science & Technology

2013-06-01

Karen M. Walker, Ph.D. William L. Farmer, Ph.D. Rebecca C. Roberts, MS Navy Personnel Research, Studies, and Technology NPRST-TR-13-2...June 2013 Suitability Screening Test for Marine Corps Air Traffic Controllers Phase II Karen M. Walker, Ph.D. William L. Farmer, Ph.D. Rebecca...C. Roberts, MS Navy Personnel Research, Studies, and Technology Reviewed by Tanja Blackstone , Ph.D. Approved and released by D. M. Cashbaugh

Value of bacterial culture of vaginal swabs in diagnosis of vaginal infections.

PubMed

Nenadić, Dane; Pavlović, Miloš D

2015-06-01

Vaginal and cervical swab culture is still very common procedure in our country's everyday practice whereas simple and rapid diagnostic methods have been very rarely used. The aim of this study was to show that the employment of simple and rapid diagnostic tools [vaginal fluid wet mount microscopy (VFWMM), vaginal pH and potassium hydroxide (KOH) test] offers better assessment of vaginal environment than standard microbiologic culture commonly used in Serbia. This prospective study included 505 asymptomatic pregnant women undergoing VFWMM, test with 10% KOH, determination of vaginal pH and standard culture of cervicovaginal swabs. Combining findings from the procedures was used to make diagnoses of bacterial vaginosis (BV) and vaginitis. In addition, the number of polymorphonuclear leukocytes (PMN) was determined in each sample and analyzed along with other findings. Infections with Candida albicans and Trichomonas vaginalis were confirmed or excluded by microscopic examination. In 36 (6%) patients cervicovaginal swab cultures retrieved several aerobes and facultative anaerobes, whereas in 52 (11%) women Candida albicans was isolated. Based on VFWMM findings and clinical criteria 96 (19%) women had BV, 19 (4%) vaginitis, and 72 (14%) candidiasis. Of 115 women with BV and vaginitis, pH 4.5 was found in 5, and of 390 with normal findings 83 (21%) had vaginal pH 4.5. Elevated numbers of PMN were found in 154 (30%) women--in 83 (54%) of them VFWMM was normal. Specificity and sensitivity of KOH test and vaginal pH determination in defining pathological vaginal flora were 95% and 81%, and 79% and 91%, respectively. Cervicovaginal swab culture is expensive but almost non-informative test in clinical practice. The use of simpler and rapid methods as vaginal fluid wet mount microscopy, KOH test and vaginal pH offers better results in diagnosis, and probably in the treatment and prevention of sequels of vaginal infections.

A simple scheme to determine potential aquatic metal toxicity from mining wastes

USGS Publications Warehouse

Wildeman, T.R.; Smith, K.S.; Ranville, J.F.

2007-01-01

A decision tree (mining waste decision tree) that uses simple physical and chemical tests has been developed to determine whether effluent from mine waste material poses a potential toxicity threat to the aquatic environment. For the chemical portion of the tree, leaching tests developed by the United States Geological Survey, the Colorado Division of Minerals and Geology (Denver, CO), and a modified 1311 toxicity characteristic leaching procedure (TCLP) test of the United States Environmental Protection Agency have been extensively used as a surrogate for readily available metals that can be released into the environment from mining wastes. To assist in the assessment, element concentration pattern graphs (ECPG) are produced that compare concentrations of selected groups of elements from the three leachates and any water associated with the mining waste. The MWDT makes a distinction between leachates or waters with pH less than or greater than 5. Generally, when the pH values are below 5, the ECPG of the solutions are quite similar, and potential aquatic toxicity from cationic metals, such as Pb, Cu, Zn, Cd, and Al, is assumed. Below pH 5, these metals are mostly dissolved, generally are not complexed with organic or inorganic ligands, and hence are more bioavailable. Furthermore, there is virtually no carbonate alkalinity at pH less than 5. All of these factors promote metal toxicity to aquatic organisms. On the other hand, when the pH value of the water or the leachates is above 5, the ECPG from the solutions are variable, and inferred aquatic toxicity depends on factors in addition to the metals released from the leaching tests. Hence, leachates and waters with pH above 5 warrant further examination of their chemical composition. Physical ranking criteria provide additional information, particularly in areas where waste piles exhibit similar chemical rankings. Rankings from physical and chemical criteria generally are not correlated. Examples of how this decision tree has been applied in assessing mine sites are discussed. Copyright ?? Taylor & Francis Group, LLC.

Fermentation pH influences the physiological-state dynamics of Lactobacillus bulgaricus CFL1 during pH-controlled culture.

PubMed

Rault, Aline; Bouix, Marielle; Béal, Catherine

2009-07-01

This study aims at better understanding the effects of fermentation pH and harvesting time on Lactobacillus bulgaricus CFL1 cellular state in order to improve knowledge of the dynamics of the physiological state and to better manage starter production. The Cinac system and multiparametric flow cytometry were used to characterize and compare the progress of the physiological events that occurred during pH 6 and pH 5 controlled cultures. Acidification activity, membrane damage, enzymatic activity, cellular depolarization, intracellular pH, and pH gradient were determined and compared during growing conditions. Strong differences in the time course of viability, membrane integrity, and acidification activity were displayed between pH 6 and pH 5 cultures. As a main result, the pH 5 control during fermentation allowed the cells to maintain a more robust physiological state, with high viability and stable acidification activity throughout growth, in opposition to a viability decrease and fluctuation of activity at pH 6. This result was mainly explained by differences in lactate concentration in the culture medium and in pH gradient value. The elevated content of the ionic lactate form at high pH values damaged membrane integrity that led to a viability decrease. In contrast, the high pH gradient observed throughout pH 5 cultures was associated with an increased energetic level that helped the cells maintain their physiological state. Such results may benefit industrial starter producers and fermented-product manufacturers by allowing them to better control the quality of their starters, before freezing or before using them for food fermentation.

pH imaging of mouse kidneys in vivo using a frequency-dependent paraCEST agent

PubMed Central

Wu, Yunkou; Zhang, Shanrong; Soesbe, Todd C.; Yu, Jing; Vinogradov, Elena; Lenkinski, Robert E.; Sherry, A. Dean

2015-01-01

Purpose This study explored the feasibility of using a pH responsive paraCEST agent to image the pH gradient in kidneys of healthy mice. Methods CEST signals were acquired on an Agilent 9.4 T small animal MRI system using a steady-state gradient echo pulse sequence after a bolus injection of agent. The magnetic field inhomogeneity across each kidney was corrected using the WASSR method and pH maps were calculated by measuring the frequency of water exchange signal arising from the agent. Results Dynamic CEST studies demonstrated that the agent was readily detectable in kidneys only between 4 to 12 min post-injection. The CEST images showed a higher signal intensity in the pelvis and calyx regions and lower signal intensity in the medulla and cortex regions. The pH maps reflected tissue pH values spanning from 6.0 to 7.5 in kidneys of healthy mice. Conclusion This study demonstrated that pH maps of the kidney can be imaged in vivo by measuring the pH-dependent chemical shift of a single water exchange CEST peak without prior knowledge of the agent concentration in vivo. The results demonstrate the potential of using a simple frequency-dependent paraCEST agent for mapping tissue pH in vivo. PMID:26173637

Benthic macroinvertebrate community structure in 20 streams of varying pH and humic content.

PubMed

Kullberg, A

1992-01-01

The structure of stream benthic macroinvertebrate communities in relation to pH and humic content was studied in 20 second and third-order forest streams in southern Sweden. Streams varied in pH from 4.2 to 8.0, and in humic content from a colour of 5 to 1200 mg Pt litre(-1). There was a positive relationship between pH and species richness, with a discontinuity occurring at pH approximately 5.7. At pH > 5.7, species richness decreased with increasing colour. At pH < 5.7 there was a positive correlation between species richness and humic concentration up to a colour of about 200-300 mg Pt litre(-1). this may be explained by high concentrations, 0.4-0.9 mg litre(-1), of labile monomeric Al occurring in the low coloured acid streams. In streams with a colour > 200 mg Pt litre(-1) labile monomeric Al was less than 0.2 mg litre(-1). There was no significant change in species richness above this threshold, but a shift in species composition towards a dominance of Plecoptera and Chironomidae. This threshold model seems to explain the observed differences in stream benthic community structure better than a simple linear relationship with pH or humic content.

Fluorapatite crystal growth from modified seawater solutions

NASA Astrophysics Data System (ADS)

Van Cappellen, Philippe; Berner, Robert A.

Seeded precipitation experiments were conducted in a pH/fluoride-stat system to study the crystal growth of fluorapatite ( FAP ) in carbonate-free NaCl-CaCl 2-NaF-Na 2HPO 4 solutions, at seawater calcium concentration, chlorinity, and pH. With increasing supersaturation, the dependence of the growth rate on the relative supersaturation changes from parabolic to exponential. This is interpreted as reflecting a transition in the crystal growth mechanism from growth at dislocation-induced surface steps to surface nucleation-controlled growth. The analysis of the kinetic data leads to a mineral-aqueous solution interfacial tension for FAP of 289 mJ/m 2. The Arrhenius activation energy of the growth reaction in the temperature range 12 to 35°C is 47 kJ/mol. The inhibition of FAP growth by Mg 2+ ions was investigated over a range of total dissolved Mg of 0 to 60 mM. At dissolved magnesium concentrations typical of marine pore waters (40-60 mM), the rate of FAP growth is 15 to 20 times slower than in the absence of Mg 2+, for the same degree of supersaturation, at 25 °C and pH = 8. The inhibitory effect can be explained by the blocking of growth sites at the surface of FAP crystals by adsorbed Mg 2+ ions. A simple Langmuir adsorption model for the retardation effect of Mg 2+ is supported by the results. The effect of pH on FAP growth was tested for pH values from 7 to 8.5. In this range, growth of FAP is catalyzed by hydrogen ions. The apparent growth rate constant is proportional to ( aH+) m where m, the rate order with respect to H +, is a non-integral number which depends on pH. At identical degrees of supersaturation, the growth rate of FAP at pH = 7 is nearly twice that at pH = 8. When corrected for bottom water temperatures, pore water pH, and the retardation of Mg 2+, the experimental growth rates predict that during burial in modern phosphatic sediments, apatite particles grow to sizes on the order of 0.1-10 μrn. The relatively slow growth kinetics of FAP are consistent with the observed small particle sizes of marine sedimentary apatite.

[The molecular-cytogenetic characterization and tyrosine kinase inhibitors efficacy in newly diagnosed chronic phase CML patients with variant Philadelphia chromosomes].

PubMed

Zhao, J J; Zhang, Y L; Zhang, S J; Zhou, J; Yu, F K; Zu, Y L; Zhao, H F; Li, Z; Song, Y P

2018-03-14

Objective: To investigate the molecular-cytogenetic characterization and impact on tyrosine kinase inhibitors (TKIs) therapy in chronic phase of chronic myeloid leukemia (CML-CP) patients with variant Ph chromosome (vPh). Methods: The clinical data of 32 patients with vPh chromosomes were collected and compared with 703 patients with typical Ph chromosome in newly diagnosed CML-CP who were on first-line imatinib (IM) and with BCR-ABL transcript of P210. Results: There was no significant difference in demographic and hematological characteristics between vPh and classic Ph patients. 3(9.4%) of the 32 vPh cases were simple variant translocations. Among the remaining 29 cases with complex variant translocations, 28 cases (87.5%) involved 3 chromosomes, and only 1 (3.1%) involved 4 chromosomes. Except for 8, 15, 18, X, and Y chromosomes, the other chromosomes were involved. The frequency of chromosome 12q(15.5%) and 1p (12.1%) were higher involved. The most common FISH signal pattern was 2G2R1Y (74.1%), followed by 1G1R2F (14.8%), 2G1R1Y (3.7%), 1G2R1Y (3.7%), 1G1R1Y (3.7%). The comparison of complete cytogenetic response (CCyR) ( P =0.269), major molecular response (MMR) ( P =0.391) were carried out between simple and complex mechanisms, without difference. Compared with the classic Ph, the patients with vPh had higher IM primary resistance rate ( χ 2 =3.978, P =0.046), especially primary hematological resistance ( χ 2 =7.870, P =0.005), but the difference of CCyR ( χ 2 =0.192, P =0.661), MMR ( χ 2 =0.822, P =0.365), EFS ( χ 2 =0.509, P =0.476), OS ( χ 2 =3.485, P =0.062) were not statistically significant, and multivariate analysis showed that the presence of vPh did not affect OS ( RR =0.692, 95% CI 0.393-1.765, P =0.658)、EFS ( RR =0.893, 95% CI 0.347-2.132, P =0.126) and PFS ( RR =1.176, 95% CI 0.643-2.682, P =0.703). Conclusion: CML-CP patients with vPh and classic Ph had similar demographic and hematological characteristics. Except for 22q11, 9q34, the frequency of chromosome 12q and 1p were higher involved. The most common FISH signal pattern was 2G2R1Y, and different mechanisms had no impact on TKIs therapy. Compared with cases with classic Ph chromosomes, the patients with vPh chromosomes had higher risk of IM primary resistance, especially primary hematological resistance, which can obtain deeper molecular response quickly after changing to second-generation TKIs and didn't affect long-term outcomes and OS.

Influence of long-term exposure to simulated acid rain on development, reproduction and acaricide susceptibility of the carmine spider mite, Tetranychus cinnabarinus

PubMed Central

Wang, Jin-Jun; Zhang, Jian-Ping; He, Lin; Zhao, Zhi-Mo

2006-01-01

Development, reproduction and acaricide susceptibility of Tetranychus cinnabarinus (Boisduvals) (Acari: Tetranychidae) were investigated after long-term (about 40 generations) exposure to various levels of acid rain; pH 2.5, 3.0, 4.0, and 5.6. Deionized water (pH 6.8) served as a control. The mites were reared on eggplant leaves at 28°C, 80%RH and a photoperiod of 14:10 (L:D) in the laboratory. The results showed that the duration of the immature stage was significantly affected by acid rain exposure. The shortest duration (8.90 days) was recorded for populations exposed to pH 5.6 acid rain, while the longest duration (9.37 days) occurred after exposure to pH 2.5 acid rain. Compared with the control population, adult longevity was shortened with an increase in acidity. Similarly, the oviposition duration was also shortened by an increase in acidity. Statistically, female fecundity did not differ significantly between pH 5.6, pH 4.0 and control populations, but did differ significantly between the control population and those exposed to pH 2.5 and pH 3.0 acid rain. This suggested that the mite suffered reproductive defects after long-term exposure to acid rain with higher acidity (pH 2.5 and 3.0). The intrinsic rate of increase among different populations was not significantly affected, but the net reproductive rate of populations exposed to pH 2.5 and 3.0 acid rain was significantly less than pH4.0, 5.6, and control populations. Bioassay results showed that after long-term exposure to acid rain, susceptibility of the mites to two acaricides, dichlorvos and fenpropathrin, did not change significantly. PMID:19537978

The pH ruler: a Java applet for developing interactive exercises on acids and bases.

PubMed

Barrette-Ng, Isabelle H

2011-07-01

In introductory biochemistry courses, it is often a struggle to teach the basic concepts of acid-base chemistry in a manner that is relevant to biological systems. To help students gain a more intuitive and visual understanding of abstract acid-base concepts, a simple graphical construct called the pH ruler Java applet was developed. The applet allows students to visualize the abundance of different protonation states of diprotic and triprotic amino acids at different pH values. Using the applet, the student can drag a widget on a slider bar to change the pH and observe in real time changes in the abundance of different ionization states of this amino acid. This tool provides a means for developing more complex inquiry-based, active-learning exercises to teach more advanced topics of biochemistry, such as protein purification, protein structure and enzyme mechanism.

Spatial variability of isoproturon mineralizing activity within an agricultural field: geostatistical analysis of simple physicochemical and microbiological soil parameters.

PubMed

El Sebai, T; Lagacherie, B; Soulas, G; Martin-Laurent, F

2007-02-01

We assessed the spatial variability of isoproturon mineralization in relation to that of physicochemical and biological parameters in fifty soil samples regularly collected along a sampling grid delimited across a 0.36 ha field plot (40 x 90 m). Only faint relationships were observed between isoproturon mineralization and the soil pH, microbial C biomass, and organic nitrogen. Considerable spatial variability was observed for six of the nine parameters tested (isoproturon mineralization rates, organic nitrogen, genetic structure of the microbial communities, soil pH, microbial biomass and equivalent humidity). The map of isoproturon mineralization rates distribution was similar to that of soil pH, microbial biomass, and organic nitrogen but different from those of structure of the microbial communities and equivalent humidity. Geostatistics revealed that the spatial heterogeneity in the rate of degradation of isoproturon corresponded to that of soil pH and microbial biomass.

Label-Free Carbon-Dots-Based Ratiometric Fluorescence pH Nanoprobes for Intracellular pH Sensing.

PubMed

Shangguan, Jingfang; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Xu, Fengzhou; Liu, Jinquan; Tang, Jinlu; Yang, Xue; Huang, Jin

2016-08-02

Measuring pH in living cells is of great importance for better understanding cellular functions as well as providing pivotal assistance for early diagnosis of diseases. In this work, we report the first use of a novel kind of label-free carbon dots for intracellular ratiometric fluorescence pH sensing. By simple one-pot hydrothermal treatment of citric acid and basic fuchsin, the carbon dots showing dual emission bands at 475 and 545 nm under single-wavelength excitation were synthesized. It is demonstrated that the fluorescence intensities of the as-synthesized carbon dots at the two emissions are pH-sensitive simultaneously. The intensity ratio (I475 nm/I545 nm) is linear against pH values from 5.2 to 8.8 in buffer solution, affording the capability as ratiometric probes for intracellular pH sensing. It also displays that the carbon dots show excellent reversibility and photostability in pH measurements. With this nanoprobe, quantitative fluorescence imaging using the ratio of two emissions (I475 nm/I545 nm) for the detection of intracellular pH were successfully applied in HeLa cells. In contrast to most of the reported nanomaterials-based ratiometric pH sensors which rely on the attachment of additional dyes, these carbon-dots-based ratiometric probes are low in toxicity, easy to synthesize, and free from labels.

Salivary pH as a marker of plasma adiponectin concentrations in Women.

PubMed

Tremblay, Monique; Loucif, Yacine; Methot, Julie; Brisson, Diane; Gaudet, Daniel

2012-02-03

Plasma adiponectin is a significant correlate of the pro-inflammatory cardiometabolic risk profile associated with obesity and type 2 diabetes. Salivary pH is influenced by several cardiometabolic risk components such as inflammation, oxidation and numerous oral and systemic health modulators, including the menopausal status. This study aimed to assess the association between plasma adiponectin concentrations and salivary pH in women according to the menopausal status. Unstimulated saliva collection was performed in 151 Caucasian women of French-Canadian origin (53 premenopausal women (PMW) and 98 menopausal women (MW)). Student's t test, ANOVA and linear regression models were used to assess the association between plasma adiponectin concentrations and salivary pH. Plasma adiponectin levels increased as a function of salivary pH in the whole sample and among MW (r = 0.29 and r = 0.36, p < 0.001). The proportion of the variance of plasma adiponectin levels explained by the salivary pH (R2) was 10.8% (p < 0.001). Plasma adiponectin levels progressively increased across salivary pH quartiles (p = 0.005). These results suggest that salivary pH is a significant correlate of plasma adiponectin levels in women. With the increasing prevalence of type 2 diabetes and obesity, new technologies should be developed to more easily monitor health status, disease onset and progression. Salivary pH, a simple, inexpensive and non-invasive measure, could be a very promising avenue.

Photosynthetically Driven Cycles Produce Extreme pCO2Variability in a Large Eelgrass Meadow and Readily Measured Proxies Can Be Used to Estimate These Changes

NASA Astrophysics Data System (ADS)

Love, B. A.; O'Brien, C.; Bohlmann, H.

2016-02-01

Declining ocean pH has spurred research into the effects of marine carbonate chemistry on a variety of organisms, but less work has focused on the potential role of organisms in changing local carbonate chemistry. It has been suggested that photosynthetic activity of macrophytes in coastal areas can decrease pCO2, increase pH, and may provide areas of refuge for organisms sensitive to ocean acidification. To assess the effect of a large eelgrass meadow on water chemistry, discreet samples were collected hourly over several 24 hour cycles in Padilla Bay, Washington. Calculated pCO2 ranged from less than 100 ppm to greater than 700 ppm, often over the course of only a few hours. Aragonite saturation, DIC and pH were also highly variable. In -situ sensors, including a YSI glass electrode, a custom built DuraFET sensor and a SeaFET sensor were co-deployed to provide a high frequency record of water chemistry over several months. These data, (discrete samples and sensors) were used to develop a model that estimates pCO2 for the summer season based on readily measured parameters. Tidal height, photosynthetically active radiation and pH can predict pCO2 reasonably well in this environment. We compare the data from the 3 pH sensors and analyze the quality of data and predictions based on each one. A simple theoretical model shows that the large observed and modeled changes in pCO2 and pH (up to 800 ppm CO2 or 1 pH unit per day) match the magnitude of changes expected based on experimentally derived photosynthetic rates, measured light and water depth and that CO2 fluxes from gas exchange are expected to be small compared to photosynthetic fluxes in this environment. This study illustrates how eelgrass meadows do have the potential to create favorable carbonate chemistry, and demonstrates both the temporally variable nature of that effect and the possibility of better understanding when and how long it occurs through relatively simple modeling of the system.

Leaching of APC residues from secondary Pb metallurgy using single extraction tests: the mineralogical and the geochemical approach.

PubMed

Ettler, Vojtech; Mihaljevic, Martin; Sebek, Ondrej; Strnad, Ladislav

2005-05-20

Two air-pollution-control (APC) residues--one from flue gas cooling with alkaline water and one from deionized water cooling--from secondary lead metallurgy were submitted to two different standardized short-term leaching protocols: US EPA toxicity characteristic leaching procedure (TCLP) and static leaching according to Czech/European norm EN 12457-2. The experimental procedure was coupled with detailed mineralogical investigation of the solid material (SEM, XRPD) and speciation-solubility calculations using the PHREEQC-2 geochemical code. Both types of residues were considered as hazardous materials exhibiting substantial leaching of Pb (up to 7130 mg/l) and other inorganic contaminants. However, the APC residue produced by flue gas cooling with alkaline water (sample B) exhibits more favourable leaching and environmental characteristics than that produced by simple deionised water cooling (sample A). At pH < 5, primary caracolite (Na3Pb2(SO4)3Cl) and potassium lead chloride (KCl.2PbCl2) are completely or partially dissolved and transformed to residual anglesite (PbSO4), cotunnite (PbCl2) and laurionite (Pb(OH)Cl). At pH 5-6, anglesite is still the principal residual product, whereas at pH > 6, phosgenite (PbCl2.PbCO3) became the dominant secondary phase. The results are consistent with the mineralogical and geochemical studies focused on acidic forest soils highly polluted by smelter emissions, where anglesite, as a unique Pb-bearing phase, has been detected. From the technological point of view, the mixing of APC residue with alkaline water, followed by an increase in the suspension pH and equilibration with atmospheric CO2, may be used to ensure the precipitation of less soluble Pb carbonates, which are more easily recycled in the Pb recovery process in the metallurgical plant.

Emulsion Solvent Evaporation-Induced Self-Assembly of Block Copolymers Containing pH-Sensitive Block.

PubMed

Wu, Yuqing; Wang, Ke; Tan, Haiying; Xu, Jiangping; Zhu, Jintao

2017-09-26

A simple yet efficient method is developed to manipulate the self-assembly of pH-sensitive block copolymers (BCPs) confined in emulsion droplets. Addition of acid induces significant variation in morphological transition (e.g., structure and surface composition changes) of the polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) assemblies, due to the hydrophobic-hydrophilic transition of the pH-sensitive P4VP block via protonation. In the case of pH > pKa (P4VP) (pKa (P4VP) = 4.8), the BCPs can self-assemble into pupa-like particles because of the nearly neutral wetting of PS and P4VP blocks at the oil/water interface. As expected, onion-like particles obtained when pH is slightly lower than pKa (P4VP) (e.g., pH = 3.00), due to the interfacial affinity to the weakly hydrophilic P4VP block. Interestingly, when pH was further decreased to ∼2.5, interfacial instability of the emulsion droplets was observed, and each emulsion droplet generated nanoscale assemblies including vesicles, worm-like and/or spherical micelles rather than a nanostructured microparticle. Furthermore, homopolymer with different molecular weights and addition ratio are employed to adjust the interactions among copolymer blocks. By this means, particles with hierarchical structures can be obtained. Moreover, owing to the kinetically controlled processing, we found that temperature and stirring speed, which can significantly affect the kinetics of the evaporation of organic solvent and the formation of particles, played a key role in the morphology of the assemblies. We believe that manipulation of the property for the aqueous phase is a promising strategy to rationally design and fabricate polymeric assemblies with desirable shapes and internal structures.

The Computer as Lab Partner.

ERIC Educational Resources Information Center

Nicklin, R. C.

1985-01-01

Microcomputers can record laboratory measurements which human laboratory partners can never collect. Simple, harder, and general-purpose interfaces are discussed, with suggestions for several experiments involving an exercise bike, acceleration, and pendulums. Additional applications with pH meters, spectrophotometers, and chromatographs are also…

Removal of sulphates acidity and iron from acid mine drainage in a bench scale biochemical treatment system.

PubMed

Prasad, D; Henry, J G

2009-02-01

The focus of this study was to develop a simple biochemical system to treat acid mine drainage for its safe disposal. Recovery and reuse of the metals removed were not considered. A three-step process for the treatment of acid mine drainage (AMD), proposed earlier, separates sulphate reducing activity from metal precipitation units and from a pH control system. Following our earlier work on the first step (biological reactor), this paper examines the second step (i.e. chemical reactor). The objectives of this study were: (1) to determine the increase in pH and the reduction of iron in the chemical reactor for different proportions of simulated AMD, and (2) to assess the capability of the chemical reactor. A series of experiments was conducted to study the effects of addition of alkaline sulphidogenic liquor (ASL) derived from a batch sulphidogenic biological reactor (operating with activated sludge and a COD/SO4 ratio of 1.6) on the simulated AMD characteristics. At 60-minute contact time, addition of 30% ASL (pH of 7.60-7.76) to the chemical reactor with 70% AMD (pH of 1.65-2.02), increased the pH of the AMD to 6.57 and alkalinity from 0 to 485 mg l(-1) as CaCO3, respectively and precipitated about 97% of the iron present in the simulated AMD. Others have demonstrated that metals in mine drainage can be precipitated by bacterial sulphate reduction. In this study, iron, a common and major component of mine drainage was used as a surrogate for metals in general. The results indicate the feasibility of treating AMD by an engineered sulphidogenic anaerobic reactor followed by a chemical reactor and that our three-step biochemical process has important advantages over other conventional AMD treatment systems.

Effects of Carbon Addition on Iron and Phosphorus in a Highly Weathered Tropical Soil

NASA Astrophysics Data System (ADS)

Liptzin, D.; Silver, W. L.

2008-12-01

In the highly weathered iron (Fe)-rich soils of wet tropical forests, Fe may play a key role in controlling ecosystem processes because of its interactions with carbon (C) and phosphorus (P). The high NPP typical of tropical forests contributes significantly to the global C cycle. In Fe-rich tropical soils, NPP is thought to be limited by P. The periodic reducing conditions that occur in upland tropical soils may be associated with pulses of increased P availability because of the release of Fe-bound P during iron reduction. While little is known about the factors controlling Fe reduction in soils, it is likely that C availability plays a role. Typically, only simple C sources like acetate or glucose have been used to examine this limitation. However, the source of much of the C in nature is the complex mixture of organic compounds leached from leaves and litter. To investigate the linkages between Fe, C, and P, we compared the effects adding either acetate (200 mg C/L) or leaf leachate in low (50-100 mg C/L) or high (150-200 mg C/L) concentrations to incubated soils from a tropical rain forest in Puerto Rico under ambient atmospheric conditions. We measured pools of iron and phosphorus as well as pH at four time points over a month. Both Fe(II) and pH exhibited significant treatment effects, but not until the last sampling date. At this time, the Fe(II) concentration could explain 49% of the variability in soil pH. The pH was significantly higher in the acetate treatments than both the leaf leachate treatments. While Fe(II) concentration was significantly higher in the acetate treatment than the control and low leaf leachate treatment, there was no difference compared to the high leaf leachate treatment After one month microbial biomass P had increased significantly while the NaOH extractable organic P had decreased significantly. These changes suggest the rapid microbial uptake of P liberated from Fe. In conclusion, microbes appear to utilize more complex C in leaf leachate at a similar rate as acetate to promote Fe reduction. The simultaneous immobilization of P by microbes during the incubation suggests that periodic reducing conditions in the field may be associated with enhanced microbial activity and carbon cycling in these highly productive ecosystems.

Precipitation of molybdenum(V) as the hydroxide and its separation from rhenium.

PubMed

Yatirajam, V; Ahuja, U; Kakkar, L R

1975-03-01

A study of the conditions for precipitation of molybdenum(V) hydroxide shows that for Mo concentration 1 mg ml about 97.5% of the Mo can be precipitated between pH 5 and 5.8. Lower concentrations of molybdenum(V) or molybdenum(VI) can be precipitated quantitatively by using 20 times the amount of zirconium as collector, at the same pH. On this basis, a simple method is given for quantitative separation of rhenium from large amounts of molybdenum and is attested by analysis of synthetic and molybdenite samples.

Cervical and vaginal microflora of women under cancer screening.

PubMed

Ternai, A; Kulcsár, G; Dán, P; Pataki, I; Veszelovszky, I; Nász, I

1987-01-01

Gynaecological cancer screening was supplemented with examination of the vaginal microflora and pH in women suffering from vaginal discharge and/or colpitis. In alkaline samples Escherichia coli, Staphylococcus aureus and Candida albicans and, in cervical epithelial cells, herpes simplex virus antigen were of common occurrence, while in samples with acid reaction Trichomonas and, in cervical cells mainly from pregnant women, adenovirus antigen were often detected. Since vaginal pH may be informative of the pathogenic agent(s), its estimation by a rapid, simple and painless procedure, like litmus paper reaction, is recommended.

pH controls over methanogenesis and iron reduction along soil depth profile in Arctic tundra

NASA Astrophysics Data System (ADS)

Zheng, J.; Gu, B.; Wullschleger, S. D.; Graham, D. E.

2017-12-01

Increasing soil temperature in the Arctic is expected to accelerate rates of soil organic matter decomposition. However, the magnitude of this impact is uncertain due to the many physical, chemical, and biological processes that control the decomposition pathways. Varying soil redox conditions present a key control over pathways of organic matter decomposition by diverting the flow of reductants among different electron accepting processes and further driving acid-base reactions that alter soil pH. In this study we investigated the pH controls over anaerobic carbon mineralization, methanogenesis, Fe(III) reduction and the interplay between these processes across a range of pH and redox conditions. pH manipulation experiments were conducted by incubating soils representing organic, mineral, cryoturbated transitional layers and permafrost. In the experiments we sought to understand (1) if methanogenesis or Fe(III) reduction had similar pH optima; (2) if this pH response also occurs at `upstream' fermentation process; and (3) if pH alters organo-mineral association or organic matter sorption and desorption and its availability for microbial degradation. Our preliminary results suggest that the common bell-shaped pH response curve provides a good fit for both Fe(III) reduction and methanogenesis, with optimum pH at 6.0-7.0. Exceptions to this were found in transitional layer where methanogenesis rates positively correlated with increasing pH, with maximum rates measured at pH 8.5. It is likely that the transitional layer harbors distinct groups of methanogens that prefer a high pH. Variations in the optimum pH of Fe(III) reduction and methanogenesis may play a significant role in regulating organic matter decomposition pathways and thus greenhouse gas production in thawing soils. These results support biogeochemical modeling efforts to accurately simulate organic matter decomposition under changing redox and pH conditions.

The Urinary Uric Acid/Creatinine Ratio is An Adjuvant Marker for Perinatal Asphyxia.

PubMed

Bhongir, Aparna Varma; Yakama, Akhil Varma Venkata; Saha, Subhajit; Radia, Sejal B; Pabbati, Jayalakshmi

2015-09-01

To assess the urinary uric acid/creatinine ratio (UA/Cr) in relation to Apgar score and cord blood gas analysis in identification of perinatal asphyxia and to define the cutoff values. case control study. The newborns admitted in the department of pediatrics and NICU of Mediciti Institute of Medical Science, Ghanpur, Medchal mandal, Telangana from May-July 2011 were enrolled. The study was conducted on 31 (18 males, 13 females) controls and 18 (12males, 6 females) asphyxiated neonates. 5ml of arterial cord blood of newborn collected at the time of birth and spot urine samples were collected within 24-72 hours of life. Cord blood gas analysis were done immediately and Urinary uric acid was measured by modified Uricase method, urinary creatinine by modified kinetic Jaffe's reaction. The mean urinary uric acid and creatinine ratio (2.58± 0.48 vs 1.89 ± 0.59) is significantly higher in Asphyxiated group than in the control group. The umbilical cord blood pH had significant positive correlation with 1 st minute Apgar score (r= 0.41, p=0.003), 5 th minute Apgar (r= 0.44, p=0.002), while urinary UA/Cr ratio had significant negative correlation with cord blood pH (r= -0.63, p=0.002). Urinary UA/Cr ratio with criterion of >2.43 had 80% sensitivity, 87.5% specificity with AUC of 0.84 (p=0.003) had a better predictive value. Urinary UA/Cr ratio is easy, non-invasive, painless and economical adjuvant parameter with better predictive value for diagnosing perinatal asphyxia with simple diagnostic equipment.

CORROSION CONTROL: IT'S NOT JUST GETTING THE LEAD OUT

EPA Science Inventory

This presentation will focus on the three corrosion control strategies applied in New England including: pH adjustment alone, pH adjustment with carbonate alkalinity supplementation, and pH adjustment with phosphate addition. The consequences of these changes will be discussed in...

Electrodeionization method

DOEpatents

Lin, YuPo J.; Hestekin, Jamie; Arora, Michelle; St. Martin, Edward J.

2004-09-28

An electrodeionization method for continuously producing and or separating and/or concentrating ionizable organics present in dilute concentrations in an ionic solution while controlling the pH to within one to one-half pH unit method for continuously producing and or separating and/or concentrating ionizable organics present in dilute concentrations in an ionic solution while controlling the pH to within one to one-half pH unit.

Simple and sensitive determination of five quinolones in food by liquid chromatography with fluorescence detection.

PubMed

Ramos, Macarena; Aranda, Angela; Garcia, Elena; Reuvers, Thea; Hooghuis, Henny

2003-06-15

A simple and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the determination of five different quinolones: enrofloxacin, ciprofloxacin, sarafloxacin, oxolinic acid and flumequine in pork and salmon muscle. The method includes one extraction and clean-up step for the five quinolones together which are detected in two separated HPLC runs by means of their fluorescence. The proposed analytical method involves homogenizing of the tissue sample with 0.05 M phosphate buffer, pH 7.4 and clean-up by Discovery DS-18 cartridges. For chromatographic separation a Symmetry C(18) column is used in two different runs: (1) ciprofloxacin, enrofloxacin and sarafloxacin with acetonitrile-0.02 M phosphate buffer pH 3.0 (18:82) as mobile phase and the detector at excitation wavelength: 280 nm and emission wavelength 450 nm; and (2) oxolinic acid and flumequine with acetonitrile-0.02 M phosphate buffer pH 3.0 (34:66) as mobile phase and excitation wavelength: 312 nm and emission wavelength: 366 nm. Detection limit was as low as 5 ng g(-1), except for sarafloxacin which had a limit of 10 ng g(-1). Standard curves using blank muscle tissues spiked at different levels showed a good linear correlation coefficient, r(2) higher than 0.999 for all quinolones.

Slow Proton Transfer Coupled to Unfolding Explains the Puzzling Results of Single-Molecule Experiments on BBL, a Paradigmatic Downhill Folding Protein

PubMed Central

Cerminara, Michele; Campos, Luis A.; Ramanathan, Ravishankar; Muñoz, Victor

2013-01-01

A battery of thermodynamic, kinetic, and structural approaches has indicated that the small α-helical protein BBL folds-unfolds via the one-state downhill scenario. Yet, single-molecule fluorescence spectroscopy offers a more conflicting view. Single-molecule experiments at pH 6 show a unique half-unfolded conformational ensemble at mid denaturation, whereas other experiments performed at higher pH show a bimodal distribution, as expected for two-state folding. Here we use thermodynamic and laser T-jump kinetic experiments combined with theoretical modeling to investigate the pH dependence of BBL stability, folding kinetics and mechanism within the pH 6–11 range. We find that BBL unfolding is tightly coupled to the protonation of one of its residues with an apparent pKa of ∼7. Therefore, in chemical denaturation experiments around neutral pH BBL unfolds gradually, and also converts in binary fashion to the protonated species. Moreover, under the single-molecule experimental conditions (denaturant midpoint and 279 K), we observe that proton transfer is much slower than the ∼15 microseconds folding-unfolding kinetics of BBL. The relaxation kinetics is distinctly biphasic, and the overall relaxation time (i.e. 0.2–0.5 ms) becomes controlled by the proton transfer step. We then show that a simple theoretical model of protein folding coupled to proton transfer explains quantitatively all these results as well as the two sets of single-molecule experiments, including their more puzzling features. Interestingly, this analysis suggests that BBL unfolds following a one-state downhill folding mechanism at all conditions. Accordingly, the source of the bimodal distributions observed during denaturation at pH 7–8 is the splitting of the unique conformational ensemble of BBL onto two slowly inter-converting protonation species. Both, the unprotonated and protonated species unfold gradually (one-state downhill), but they exhibit different degree of unfolding at any given condition because the native structure is less stable for the protonated form. PMID:24205082

In situ investigation of complex BaSO4 fiber generation in the presence of sodium polyacrylate. 1. Kinetics and solution analysis.

PubMed

Wang, Tongxin; Cölfen, Helmut

2006-10-10

Simple solution analysis of the formation mechanism of complex BaSO(4) fiber bundles in the presence of polyacrylate sodium salt, via a bioinspired approach, is reported. Titration of the polyacrylate solution with Ba(2+) revealed complex formation and the optimum ratio of Ba(2+) to polyacrylate for a slow polymer-controlled mineralization process. This is a much simpler and faster method to determine the appropriate additive/mineral concentration pairs as opposed to more common crystallization experiments in which the additive/mineral concentration is varied. Time-dependent pH measurements were carried out to determine the concentration of solution species from which BaSO(4) supersaturation throughout the fiber formation process can be calculated and the second-order kinetics of the Ba(2+) concentration in solution can be identified. Conductivity measurements, pH measurements, and analytical ultracentrifugation revealed the first formed species to be Ba-polyacrylate complexes. A combination of the solution analysis results and optical microscopic images allows a detailed picture of the complex precipitation and self-organization process, a particle-mediated process involving mesoscopic transformations, to be revealed.

Selective recovery of molybdenum from spent HDS catalyst using oxidative soda ash leach/carbon adsorption method.

PubMed

Park, Kyung Ho; Mohapatra, D; Reddy, B Ramachandra

2006-11-16

The petroleum refining industry makes extensive use of hydroprocessing catalysts. These catalysts contain environmentally critical and economically valuable metals such as Mo, V, Ni and Co. In the present study, a simple hydrometallurgical processing of spent hydrodesulphurization (HDS) catalyst for the recovery of molybdenum using sodium carbonate and hydrogen peroxide mixture was investigated. Recovery of molybdenum was largely dependent on the concentrations of Na2CO3 and H2O2 in the reaction medium, which in turn controls the pH of leach liquor and the presence of Al and Ni as impurities. Under the optimum leaching conditions (40 g L(-1) Na2CO3, 6 vol.% H2O2, room temperature, 1h) about 85% recovery of Mo was achieved. The leach liquor was processed by the carbon adsorption method, which selectively adsorbs Mo at pH around 0.75. Desorption of Mo was selective at 15 vol.% NH4OH. With a single stage contact, it was found possible to achieve >99%, adsorption and desorption efficiency. Using this method, recovery of molybdenum as MoO3 product of 99.4% purity was achieved.

Improving profitability through slurry management: a look at the impact of slurry pH on various glass types

NASA Astrophysics Data System (ADS)

Hooper, Abigail R.; Boffa, Christopher C.; Sarkas, Harry W.; Cureton, Kevin

2015-08-01

When building an optical system, optical fabricators and designers meticulously choose the glass types for their application knowing that each one will have different chemical, thermal and mechanical properties. As the requirements for new optical systems have grown more demanding, the range of available glass types has vastly expanded and the specifications on the produced products have grown tighter. In an attempt to simplify processes and streamline consumable purchases, optical polishing houses often rely on one polishing slurry to manage these vast array of glass types. An unforeseen consequence of these practices can be a reduction in productivity by reduced removal rate, poor yields and frequent rework all translating into higher costs and reduced profitability. In this paper, the authors will examine the impact slurry pH has on glass types of different compositions and chemical, thermal and mechanical properties when using a double-sided polishing process. Experiments will use material removal rate, surface quality, and surface figure to provide insight into improving process control for differing glass types. Further guidance will be provided on how simple on-site monitoring and adjustment can deliver improved profitability on challenging substrates.

Potassium ferrate treatment of RFETS` contaminated groundwater

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

NONE

1995-01-01

The potassium ferrate treatment study of Rocky Flats Environmental Technology Site (RFETS) groundwater was performed under the Sitewide Treatability Studies Program (STSP). This study was undertaken to determine the effectiveness of potassium ferrate in a water treatment system to remove the contaminants of concern (COCS) from groundwater at the RFETS. Potassium ferrate is a simple salt where the iron is in the plus six valence state. It is the iron at the plus six valence state (Fe {sup +6}) that makes it an unique water treatment chemical, especially in waters where the pH is greater than seven. In basic solutionsmore » where the solubility of the oxides/hydroxides of many of the COCs is low, solids are formed as the pH is raised. By using ferrate these solids are agglomerated so they can be effectively removed by sedimentation in conventional water treatment equipment. The objective of this study was to determine the quality of water after treatment with potassium ferrate and to determine if the Colorado Water Quality Control Commission (CWQCC) discharge limits for the COCs listed in Table 1.0-1 could be met. Radionuclides in the groundwater were of special concern.« less

Accurate and self-consistent procedure for determining pH in seawater desalination brines and its manifestation in reverse osmosis modeling.

PubMed

Nir, Oded; Marvin, Esra; Lahav, Ori

2014-11-01

Measuring and modeling pH in concentrated aqueous solutions in an accurate and consistent manner is of paramount importance to many R&D and industrial applications, including RO desalination. Nevertheless, unified definitions and standard procedures have yet to be developed for solutions with ionic strength higher than ∼0.7 M, while implementation of conventional pH determination approaches may lead to significant errors. In this work a systematic yet simple methodology for measuring pH in concentrated solutions (dominated by Na(+)/Cl(-)) was developed and evaluated, with the aim of achieving consistency with the Pitzer ion-interaction approach. Results indicate that the addition of 0.75 M of NaCl to NIST buffers, followed by assigning a new standard pH (calculated based on the Pitzer approach), enabled reducing measured errors to below 0.03 pH units in seawater RO brines (ionic strength up to 2 M). To facilitate its use, the method was developed to be both conceptually and practically analogous to the conventional pH measurement procedure. The method was used to measure the pH of seawater RO retentates obtained at varying recovery ratios. The results matched better the pH values predicted by an accurate RO transport model. Calibrating the model by the measured pH values enabled better boron transport prediction. A Donnan-induced phenomenon, affecting pH in both retentate and permeate streams, was identified and quantified. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simultaneous LC determination of paracetamol and related compounds in pharmaceutical formulations using a carbon-based column.

PubMed

Monser, Lotfi; Darghouth, Frida

2002-03-01

A simple, rapid and convenient high performance liquid chromatographic method, which permits the simultaneous determination of paracetamol, 4-aminophenol and 4-chloracetanilide in pharmaceutical preparation has been developed. The chromatographic separation was achieved on porous graphitized carbon (PGC) column using an isocratic mixture of 80/20 (v/v) acetonitrile/0.05 M potassium phosphate buffer (pH 5.5) and ultraviolet detection at 244 nm. Correlation coefficient for calibration curves in the ranges 1-50 microg ml(-1) for paracetamol and 5-40 microg ml(-1) for 4-aminophenol and 4-chloroacetanilide were >0.99. The sensitivity of detection is 0.1 microg ml(-1) for paracetamol and 0.5 microg ml(-1) for 4-aminophenol and 4-chloroacetanilide. The proposed liquid chromatographic method was successfully applied to the analysis of commercially available paracetamol dosage forms with recoveries of 98-103%. It is suggested that the proposed method should be used for routine quality control and dosage form assay of paracetamol in pharmaceutical preparations. The chromatographic behaviour of the three compounds was examined under variable mobile phase compositions and pH, the results revealed that selectivity was dependent on the organic solvent and pH used. The retention selectivity of these compounds on PGC was compared with those of octadecylsilica (ODS) packing materials in reversed phase liquid chromatography. The ODS column gave little separation for the degradation product (4-aminophenol) from paracetamol, whereas PGC column provides better separation in much shorter time.

Analysis of volatile human urinary metabolome by solid-phase microextraction in combination with gas chromatography-mass spectrometry for biomarker discovery: application in a pilot study to discriminate patients with renal cell carcinoma.

PubMed

Monteiro, Márcia; Carvalho, Márcia; Henrique, Rui; Jerónimo, Carmen; Moreira, Nathalie; de Lourdes Bastos, Maria; de Pinho, Paula Guedes

2014-07-01

A new and simple analytical approach consisting of headspace-solid phase microextraction (HS-SPME) sampling coupled with gas chromatography-ion trap/mass spectrometry (GC-IT/MS) was developed to study the volatile human urinary metabolome. A central composite design (CCD) was used in the optimisation of extraction conditions. Fibre selection and evaluation of pH influence were performed using an univariate mode and the influence of other parameters, such as the time and temperature of extraction, time of incubation and salt addition, that affect the efficiency of the SPME sampling, was carried out using a CCD. With a sample volume of 2 mL, the optimal conditions in terms of total response values and reproducibility were achieved by performing analyses with a divinylbenzene/polydimethylsiloxane (DVB/PDMS) fibre, in an acidic pH (pH 2) with the addition of 0.59 g of NaCl, allowing the sample to equilibrate for 9 min and extracting at 68 °C for 24 min. The applicability of the optimised method was then tested in a pilot non-target analysis of urine samples obtained from patients with renal cell carcinoma (RCC) and healthy individuals. Chemometric unsupervised analyses performed on the volatile pattern acquired for these samples clearly showed the potential of volatile urinary metabolome to discriminate between RCC and control patients. Copyright © 2014 Elsevier Ltd. All rights reserved.

Duodenal pH in health and duodenal ulcer disease: effect of a meal, Coca-Cola, smoking, and cimetidine.

PubMed Central

McCloy, R F; Greenberg, G R; Baron, J H

1984-01-01

Intraluminal duodenal pH was recorded using a combined miniature electrode and logged digitally every 10 or 20 seconds for five hours (basal/meal/drink) in eight control subjects and 11 patients with duodenal ulcer (five on and off treatment with cimetidine). Over the whole test there were no significant differences in duodenal mean pH or log mean hydrogen ion activity (LMHa) between control subjects and patients with duodenal ulcer, but there were significantly longer periods of duodenal acidification (pH less than 4) and paradoxically more periods of duodenal alkalinisation (pH greater than 6) in the duodenal ulcer group compared with controls. After a meal duodenal mean pH and LMHa fell significantly in both controls and patients with duodenal ulcer, with more periods of duodenal acidification and alkalinisation in the duodenal ulcer group. An exogenous acid load (Coca-Cola) significantly increased the periods of duodenal acidification, and reduced alkalinisation, in both groups. Cimetidine significantly increased mean pH and LMHa and abolished the brief spikes of acidification in four of five patients with duodenal ulcer. Peak acid output (but not basal acid output) was significantly correlated with duodenal mean pH and LMHa but not with the periods of duodenal acidification. Smoking did not affect duodenal pH in either group. PMID:6706217

Sulfate reduction in sulfuric material after re-flooding: Effectiveness of organic carbon addition and pH increase depends on soil properties.

PubMed

Yuan, Chaolei; Fitzpatrick, Rob; Mosley, Luke M; Marschner, Petra

2015-11-15

Sulfuric material is formed upon oxidation of sulfidic material; it is extremely acidic, and therefore, an environmental hazard. One option for increasing pH of sulfuric material may be stimulation of bacterial sulfate reduction. We investigated the effects of organic carbon addition and pH increase on sulfate reduction after re-flooding in ten sulfuric materials with four treatments: control, pH increase to 5.5 (+pH), organic carbon addition with 2% w/w finely ground wheat straw (+C), and organic carbon addition and pH increase (+C+pH). After 36 weeks, in five of the ten soils, only treatment +C+pH significantly increased the concentration of reduced inorganic sulfur (RIS) compared to the control and increased the soil pore water pH compared to treatment+pH. In four other soils, pH increase or/and organic carbon addition had no significant effect on RIS concentration compared to the control. The RIS concentration in treatment +C+pH as percentage of the control was negatively correlated with soil clay content and initial nitrate concentration. The results suggest that organic carbon addition and pH increase can stimulate sulfate reduction after re-flooding, but the effectiveness of this treatment depends on soil properties. Copyright © 2015 Elsevier B.V. All rights reserved.

A new wireless system for decentralised measurement of physiological parameters from shake flasks

PubMed Central

Vasala, Antti; Panula, Johanna; Bollók, Monika; Illmann, Lutz; Hälsig, Christian; Neubauer, Peter

2006-01-01

Background Shake flasks are widely used because of their low price and simple handling. Many researcher are, however, not aware of the physiological consequences of oxygen limitation and substrate overflow metabolism that occur in shake flasks. Availability of a wireless measuring system brings the possibilities for quality control and design of cultivation conditions. Results Here we present a new wireless solution for the measurement of pH and oxygen from shake flasks with standard sensors, which allows data transmission over a distance of more than 100 metres in laboratory environments. This new system was applied to monitoring of cultivation conditions in shake flasks. The at-time monitoring of the growth conditions became possible by simple means. Here we demonstrate that with typical protocols E. coli shake flask cultures run into severe oxygen limitation and the medium is strongly acidified. Additionally the strength of the new system is demonstrated by continuous monitoring of the oxygen level in methanol-fed Pichia pastoris shake flask cultures, which allows the optimisation of substrate feeding for preventing starvation or methanol overfeed. 40 % higher cell density was obtained by preventing starvation phases which occur in standard shake flask protocols by adding methanol when the respiration activity decreased in the cultures. Conclusion The here introduced wireless system can read parallel sensor data over long distances from shake flasks that are under vigorous shaking in cultivation rooms or closed incubators. The presented technology allows centralised monitoring of decentralised targets. It is useful for the monitoring of pH and dissolved oxygen in shake flask cultures. It is not limited to standard sensors, but can be easily adopted to new types of sensors and measurement places (e.g., new sensor points in large-scale bioreactors). PMID:16504107

Stabilizing the baseline current of a microbial fuel cell-based biosensor through overpotential control under non-toxic conditions.

PubMed

Stein, Nienke E; Hamelers, Hubertus V M; Buisman, Cees N J

2010-04-01

A MFC-based biosensor can act as online toxicity sensor. Electrical current is a direct linear measure for metabolic activity of electrochemically active microorganisms. Microorganisms gain energy from anodic overpotential and current strongly depends on anodic overpotential. Therefore control of anodic overpotential is necessary to detect toxic events and prevent false positive alarms. Anodic overpotential and thus current is influenced by anode potential, pH, substrate and bicarbonate concentrations. In terms of overpotential all factor showed a comparable effect, anode potential 1.2% change in current density per mV, pH 0.43%/mV, bicarbonate 0.75%/mV and acetate 0.8%/mV. At acetate saturation the maximum acetate conversion rate is reached and with that a constant bicarbonate concentration. Control of acetate and bicarbonate concentration can be less strict than control of anode potential and pH. Current density changes due to changing anode potential and pH are in the same order of magnitude as changes due to toxicity. Strict control of pH and anode potential in a small range is required. The importance of anodic overpotential control for detection of toxic compounds is shown. To reach a stable baseline current under nontoxic conditions a MFC-based biosensor should be operated at controlled anode potential, controlled pH and saturated substrate concentrations. 2009 Elsevier B.V. All rights reserved.

Infectious pancreatic necrosis virus in fish by-products is inactivated with inorganic acid (pH 1) and base (pH 12).

PubMed

Myrmel, M; Modahl, I; Nygaard, H; Lie, K M

2014-04-01

The aquaculture industry needs a simple, inexpensive and safe method for the treatment of fish waste without heat. Microbial inactivation by inorganic acid (HCl) or base (KOH) was determined using infectious pancreatic necrosis virus (IPNV) as a model organism for fish pathogens. Salmonella and spores of Clostridium perfringens were general hygiene indicators in supplementary examinations. IPNV, which is considered to be among the most chemical- and heat-resistant fish pathogens, was reduced by more than 3 log in 4 h at pH 1.0 and pH 12.0. Salmonella was rapidly inactivated by the same treatment, whereas spores of C. perfringens were hardly affected. The results indicate that low and high pH treatment could be particularly suitable for fish waste destined for biogas production. pH treatment at aquaculture production sites could reduce the spread of fish pathogens during storage and transportation without disturbing the anaerobic digestion process. The treatment could also be an alternative to the current energy-intensive steam pressure sterilization of fish waste to be used by the bioenergy, fertilizer and soil improver industries. © 2013 John Wiley & Sons Ltd.

POLAROGRAPHIC BEHAVIOUR OF INDIUM IN THE PRESENCE OF TRIHYDROXYGLUTARIC ACID (in Russian)

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

Vinogradova, E.N.; An, C.

1961-09-01

The polarographic behavtor ot indium in the presence of trihydroxyglutaric acid in acid, nautral, and alkalino media was studied. The vaIue of the half-wave potental of a simple indium ion was determined in HClO/sub 4/ by the half-peak: potential during the anodic dissolutaon of and indium from an amalgam. The half-wave potential is eqia; tp 0.488 v. The effect of the concentration of trihydroxyglutaric acido on the E/sub 1/2/ of indium was studied. It was found that the regular shift of E/sub 1/2/ on changing the concentration of trihydroxyglutaric acid is observed only at pH 4 and pH ll. Themore » coordination number p = 2 and the unstability constant for the indium-trihydroxyglutaric aeid eonnplex at pH 4 were found. K (mean) is (9.73 plus or minus 0.82) x 10/sup - 11/. It was established that the process of indium reduction at pH 11 is irreversible. A method was suggested for the polarographic determination of indium and cadmium, when present together, in trihydroxyglutaric acid at pH 3 and pH 9. (auth)« less

Surface-enhanced Raman spectroscopy study on the structure changes of 4-Mercaptophenylboronic Acid under different pH conditions

NASA Astrophysics Data System (ADS)

Su, Hongyang; Wang, Yue; Yu, Zhi; Liu, Yawen; Zhang, Xiaolei; Wang, Xiaolei; Sui, Huimin; Sun, Chengbin; Zhao, Bing

2017-10-01

4-Mercaptophenylboronic Acid (4-MPBA) plays pivotal role in various fields. The orientation and existing form of the 4-MPBA strongly depend on the pH value of the media. The general aim of this work is to obtain information about the structure changes of 4-MPBA absorbed on Ag nanoparticles in different pH environment. Surface-enhanced Raman spectroscopy (SERS) technique is a simple and rapid method to study adsorption phenomena at molecule level. The investigation is done by means of SERS. In order to interpret the experimental information, a series of SERS spectra is carried out. The relative intensities of the totally symmetric (a1 mode) and non-totally symmetric (b2 mode) bands in the SERS spectra of 4-MPBA change depend on the environmental pH values, which is a manifestation of charge transfer (CT) processes. The degree of charge transfer increases with the pH value of the media changing from acidity to alkalinity. The structure changes of MPBA had been carried out in different pH environment. We envision that this approach will be of great significance in related fields of 4-MPBA-involved detection.

pH imaging of mouse kidneys in vivo using a frequency-dependent paraCEST agent.

PubMed

Wu, Yunkou; Zhang, Shanrong; Soesbe, Todd C; Yu, Jing; Vinogradov, Elena; Lenkinski, Robert E; Sherry, A Dean

2016-06-01

This study explored the feasibility of using a pH responsive paramagnetic chemical exchange saturation transfer (paraCEST) agent to image the pH gradient in kidneys of healthy mice. CEST signals were acquired on an Agilent 9.4 Tesla small animal MRI system using a steady-state gradient echo pulse sequence after a bolus injection of agent. The magnetic field inhomogeneity across each kidney was corrected using the WASSR method and pH maps were calculated by measuring the frequency of water exchange signal arising from the agent. Dynamic CEST studies demonstrated that the agent was readily detectable in kidneys only between 4 to 12 min postinjection. The CEST images showed a higher signal intensity in the pelvis and calyx regions and lower signal intensity in the medulla and cortex regions. The pH maps reflected tissue pH values spanning from 6.0 to 7.5 in kidneys of healthy mice. This study demonstrated that pH maps of the kidney can be imaged in vivo by measuring the pH-dependent chemical shift of a single water exchange CEST peak without prior knowledge of the agent concentration in vivo. The results demonstrate the potential of using a simple frequency-dependent paraCEST agent for mapping tissue pH in vivo. Magn Reson Med 75:2432-2441, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Phenotypic and functional analysis of human SLC26A6 variants in patients with familial hyperoxaluria and calcium oxalate nephrolithiasis.

PubMed

Monico, Carla G; Weinstein, Adam; Jiang, Zhirong; Rohlinger, Audrey L; Cogal, Andrea G; Bjornson, Beth B; Olson, Julie B; Bergstralh, Eric J; Milliner, Dawn S; Aronson, Peter S

2008-12-01

Urinary oxalate is a major risk factor for calcium oxalate stones. Marked hyperoxaluria arises from mutations in 2 separate loci, AGXT and GRHPR, the causes of primary hyperoxaluria (PH) types 1 (PH1) and 2 (PH2), respectively. Studies of null Slc26a6(-/-) mice have shown a phenotype of hyperoxaluria, hyperoxalemia, and calcium oxalate urolithiasis, leading to the hypothesis that SLC26A6 mutations may cause or modify hyperoxaluria in humans. Cross-sectional case-control. Cases were recruited from the International Primary Hyperoxaluria Registry. Control DNA samples were from a pool of adult subjects who identified themselves as being in good health. PH1, PH2, and non-PH1/PH2 genotypes in cases. Homozygosity or compound heterozygosity for SLC26A6 variants. Functional expression of oxalate transport in Xenopus laevis oocytes. 80 PH1, 6 PH2, 8 non-PH1/PH2, and 96 control samples were available for SLC26A6 screening. A rare variant, c.487C-->T (p.Pro163Ser), was detected solely in 1 non-PH1/PH2 pedigree, but this variant failed to segregate with hyperoxaluria, and functional studies of oxalate transport in Xenopus oocytes showed no transport defect. No other rare variant was identified specifically in non-PH1/PH2. Six additional missense variants were detected in controls and cases. Of these, c.616G-->A (p.Val206Met) was most common (11%) and showed a 30% reduction in oxalate transport. To test p.Val206Met as a potential modifier of hyperoxaluria, we extended screening to PH1 and PH2. Heterozygosity for this variant did not affect plasma or urine oxalate levels in this population. We did not have a sufficient number of cases to determine whether homozygosity for p.Val206Met might significantly affect urine oxalate. SLC26A6 was effectively ruled out as the disease gene in this non-PH1/PH2 cohort. Taken together, our studies are the first to identify and characterize SLC26A6 variants in patients with hyperoxaluria. Phenotypic and functional analysis excluded a significant effect of identified variants on oxalate excretion.

Anti-botulism single-shot vaccine using chitosan for protein encapsulation by simple coacervation.

PubMed

Sari, Roger S; de Almeida, Anna Christina; Cangussu, Alex S R; Jorge, Edson V; Mozzer, Otto D; Santos, Hércules Otacílio; Quintilio, Wagner; Brandi, Igor Viana; Andrade, Viviane Aguiar; Miguel, Angelo Samir M; Sobrinho Santos, Eliane M

2016-12-01

The aim of the present study was to compare the potency and safety of vaccines against Clostridium botulinum (C. botulinum) type C and D formulated with chitosan as controlled release matrix and vaccines formulated in conventional manner using aluminum hydroxide. Parameters were established for the development of chitosan microspheres, using simple coacervation to standardize the use of this polymer in protein encapsulation for vaccine formulation. To formulate a single shot vaccine inactivated antigens of C. botulinum type C and D were used with original toxin titles equal to 5.2 and 6.2 log LD50/ml, respectively. For each antigen a chitosan based solution of 50 mL was prepared. Control vaccines were formulated by mixing toxoid type C and D with aluminum hydroxide [25% Al(OH) 3 , pH 6.3]. The toxoid sterility, innocuity and potency of vaccines were evaluated as stipulated by MAPA-BRASIL according to ministerial directive no. 23. Encapsulation efficiency of BSA in chitosan was 32.5-40.37%, while that the encapsulation efficiency to toxoid type C was 41,03% (1.94 mg/mL) and of the toxoid type D was 32.30% (1.82 mg/mL). The single shot vaccine formulated using chitosan for protein encapsulation through simple coacervation showed potency and safety similar to conventional vaccine currently used in Brazilian livestock (10 and 2 IU/mL against C. botulinum type C and D, respectively). The present work suggests that our single shot vaccine would be a good option as a cattle vaccine against these C. botulinum type C and D. Copyright © 2016 Elsevier Ltd. All rights reserved.

A rapid and highly selective method for the estimation of pyro-, tri- and orthophosphates.

PubMed

Kamat, D R; Savant, V V; Sathyanarayana, D N

1995-03-01

A rapid, highly selective and simple method has been developed for the quantitative determination of pyro-, tri- and orthophosphates. The method is based on the formation of a solid complex of bis(ethylenediamine)cobalt(III) species with pyrophosphate at pH 4.2-4.3, with triphosphate at pH 2.0-2.1 and with orthophosphate at pH 8.2-8.6. The proposed method for pyro- and triphosphates differs from the available method, which is based on the formation of an adduct with tris(ethylenediamine)cobalt(III) species. The complexes have the composition [Co(en)(2)HP(2)O(7)]4H(2)O and [Co(en)(2)H(2)P(3)O(10)]2H(2)O, respectively. The precipitation is instantaneous and quantitative under the recommended optimum conditions giving 99.5% gravimetric yield in both cases. There is no interferences from orthophosphate, trimetaphosphate and pyrophosphate species in the triphosphate estimation up to 5% of each component. The efficacy of the method has been established by determining pyrophosphate and triphosphate contents in various matrices. In the case of orthophosphate, the proposed method differs from the available methods such as ammonium phosphomolybdate, vanadophosphomolybdate and quinoline phosphomolybdate, which are based on the formation of a precipitate, followed by either titrimetry or gravimetry. The precipitation is instantaneous and the method is simple. Under the recommended pH and other reaction conditions, gravimetric yields of 99.6-100% are obtainable. The method is applicable to orthophosphoric acid and a variety of phosphate salts.

Effect of Consuming Tea with Stevia on Salivary pH - An In Vivo Randomised Controlled Trial.

PubMed

Pallepati, Akhil; Yavagal, Puja; Veeresh, D J

To assess the effect of consuming tea with stevia on salivary pH. This randomised controlled trial employed a Latin square design. Twenty-four male students aged 20-23 years were randomly allocated to 4 different groups, 3 experimental with tea sweetened by sucrose, jaggery or stevia, and one unsweetened control. Salivary pH assessments were performed at baseline and 1 min, 20 and 60 min after consumption of the respective tea. One-way ANOVA and repeated measures ANOVA followed by Tukey's post-hoc tests were employed to analyse the data. One minute after tea consumption, the salivary pH of the sucrose group significantly decreased compared to the stevia group (p = 0.01). There was a significant difference between baseline mean salivary pH and post-interventional mean salivary pH values at all time intervals in the tea + sucrose, tea + jaggery, and plain tea groups (p < 0.01). One hour after consumption of tea, the salivary pH values reached the baseline pH in stevia and plain tea groups, but it remained lower in the sucrose and jaggery groups. The results of the present study, in which the salivary pH values returned to baseline pH 1 h after drinking stevia-sweetened tea, suggest stevia's potential as a non-cariogenic sweetener.

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

Farmer, R.W.; Dussert, B.W.; Kovacic, S.L.

Laboratory studies have identified the cause of the pH rise, which occurs during water treatment with activated carbon, as an interaction between the naturally occurring anions and protons in the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. These studies have shown that the anion sorption and resulting pH increase is independent of the raw material used for the activated carbon production, e.g. bituminous or subbituminous coal, peat, wood or coconut. Also, the pH excursions occurmore » with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of the wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface through controlled oxidation rather than the water chemistry or extended preprocessing at the treatment site.« less

Sorption/Desorption Interactions of Plutonium with Montmorillonite

NASA Astrophysics Data System (ADS)

Begg, J.; Zavarin, M.; Zhao, P.; Kersting, A. B.

2012-12-01

Plutonium (Pu) release to the environment through nuclear weapon development and the nuclear fuel cycle is an unfortunate legacy of the nuclear age. In part due to public health concerns over the risk of Pu contamination of drinking water, predicting the behavior of Pu in both surface and sub-surface water is a topic of continued interest. Typically it was assumed that Pu mobility in groundwater would be severely restricted, as laboratory adsorption studies commonly show that naturally occurring minerals can effectively remove plutonium from solution. However, evidence for the transport of Pu over significant distances at field sites highlights a relative lack of understanding of the fundamental processes controlling plutonium behavior in natural systems. At several field locations, enhanced mobility is due to Pu association with colloidal particles that serve to increase the transport of sorbed contaminants (Kersting et al., 1999; Santschi et al., 2002, Novikov et al., 2006). The ability for mineral colloids to transport Pu is in part controlled by its oxidation state and the rate of plutonium adsorption to, and desorption from, the mineral surface. Previously we have investigated the adsorption affinity of Pu for montmorillonite colloids, finding affinities to be similar over a wide range of Pu concentrations. In the present study we examine the stability of adsorbed Pu on the mineral surface. Pu(IV) at an initial concentration of 10-10 M was pre-equilibrated with montmorillonite in a background electrolyte at pH values of 4, 6 and 8. Following equilibration, aliquots of the suspensions were placed in a flow cell and Pu-free background electrolyte at the relevant pH was passed through the system. Flow rates were varied in order to investigate the kinetics of desorption and hence gain a mechanistic understanding of the desorption process. The flow cell experiments demonstrate that desorption of Pu from the montmorillonite surface cannot be modeled as a simple first order process. Furthermore, a pH dependence was observed, with less desorbed at pH 4 compared to pH 8. We suggest the pH dependence is likely controlled by reoxidation of Pu(IV) to Pu(V) and aqueous speciation. We will present models used to describe desorption behavior and discuss the implications for Pu transport. References: Kersting, A.B.; Efurd, D.W.; Finnegan, D.L.; Rokop, D.J.; Smith, D.K.; Thompson J.L. (1999) Migration of plutonium in groundwater at the Nevada Test Site, Nature, 397, 56-59. Novikov A.P.; Kalmykov, S.N.; Utsunomiya, S.; Ewing, R.C.; Horreard, F.; Merkulov, A.; Clark, S.B.; Tkachev, V.V.; Myasoedov, B.F. (2006) Colloid transport of plutonium in the far-field of the Mayak Production Association, Russia, Science, 314, 638-641. Santschi, P.H.; Roberts, K.; Guo, L. (2002) The organic nature of colloidal actinides transported in surface water environments. Environ. Sci. Technol., 36, 3711-3719. This work was funded by U. S. DOE Office of Biological & Environmental Sciences, Subsurface Biogeochemistry Research Program, and performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Security, LLC under Contract DE-AC52-07NA27344. LLNL-ABS-570161

First-Principles pH Theory

NASA Astrophysics Data System (ADS)

Kim, Yong-Hyun; Zhang, S. B.

2006-03-01

Despite being one of the most important macroscopic measures and a long history even before the quantum mechanics, the concept of pH has rarely been mentioned in microscopic theories, nor being incorporated computationally into first-principles theory of aqueous solutions. Here, we formulate a theory for the pH dependence of solution formation energy by introducing the proton chemical potential as the microscopic counterpart of pH in atomistic solution models. Within the theory, the general acid-base chemistry can be cast in a simple pictorial representation. We adopt density-functional molecular dynamics to demonstrate the usefulness of the method by studying a number of solution systems including water, small solute molecules such as NH3 and HCOOH, and more complex amino acids with several functional groups. For pure water, we calculated the auto- ionization constant to be 13.2 with a 95 % accuracy. For other solutes, the calculated dissociation constants, i.e., the so- called pKa, are also in reasonable agreement with experiments. Our first-principles pH theory can be readily applied to broad solution chemistry problems such as redox reactions.

Influence of pH on optoelectronic properties of zinc sulphide thin films prepared using hydrothermal and spin coating method

NASA Astrophysics Data System (ADS)

Choudapur, V. H.; Bennal, A. S.; Raju, A. B.

2018-04-01

The ZnS nanomaterial is synthesized by hydrothermal method under optimized conditions using Zinc acetate and sodium sulphide as precursors. The Zinc Sulphide thin films are obtained by simple spin coating method with high optical transmittance. The prepared thin films are adhesive and uniform. The x-ray diffraction analysis showed that the films are polycrystalline in cubic phase with the preferred orientation along (111) direction. Current-voltage curves were recorded at room temperature using Keithley 617 programmable electrometer and conductivity is calculated for the film coated on ITO by two probe method. The pH of the solution is varied by using ammonia and hydrochloric acid. The comparative studies of effect of pH on the morphology, crystallanity and optoelectronic properties of the films are studied. It is observed that the pH of the solution has large influence on optoelectronic properties. The thin film prepared with neutral pH has higher crystallanity, bandgap and conductivity as compared to the samples prepared in acidic or basic solutions.

Optical pH Sensor Covering the Range from pH 0-14 Compatible with Mobile-Device Readout and Based on a Set of Rationally Designed Indicator Dyes.

PubMed

Gotor, Raúl; Ashokkumar, Pichandi; Hecht, Mandy; Keil, Karin; Rurack, Knut

2017-08-15

In this work, a family of pH-responsive fluorescent probes has been designed in a rational manner with the aid of quantum chemistry tools, covering the entire pH range from 0-14. Relying on the boron-dipyrromethene (BODIPY) core, all the probes as well as selected reference dyes display very similar spectroscopic properties with ON-OFF fluorescence switching responses, facilitating optical readout in simple devices used for detection and analysis. Embedding of the probes and reference dyes into hydrogel spots on a plastic strip yielded a test strip that reversibly indicates pH with a considerably small uncertainty of ∼0.1 pH units. These strips are not only reusable but, combined with a 3D-printed case that can be attached to a smartphone, the USB port of which drives the integrated LED used for excitation, allows for autonomous operation in on-site or in-the-field applications; the developed Android application software ("app") further simplifies operation for unskilled users.

Infrared spectrum analysis of the dissociated states of simple amino acids.

PubMed

Sebben, Damien; Pendleton, Phillip

2014-11-11

In this work, we present detailed analyses of the dissociation of dilute aqueous solutions of glycine and of lysine over the range 18 resulted in consistent pKa values for the amino acids. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of pH on subunit association and heat protection of soybean alpha-galactosidase

NASA Technical Reports Server (NTRS)

Porter, J. E.; Sarikaya, A.; Herrmann, K. M.; Ladisch, M. R.; Mitchell, C. A. (Principal Investigator)

1992-01-01

Soybeans contain the enzyme alpha-galactosidase, which hydrolyzes alpha-1, 6 linkages in stachyose and raffinose to give sucrose and galactose. We have found that galactose, a competitive product inhibitor of alpha-galactosidase, strongly promotes the heat stability of the tetrameric form of the enzyme at pH 4.0 and at temperatures of up to 70 degrees C for 60 min. Stachyose and raffinose also protect alpha-galactosidase from denaturation at pH 4.0 although to a lesser extent. Glucose and mannose have little effect. At pH 7.0 the enzyme is a monomer, and galactose has no effect on the heat stability of the enzyme. In the absence of heat protection of the enzyme by added sugars, a series deactivation mechanism was found to describe the deactivation data. In comparison, a unimolecular, non-first order deactivation model applies at pH 4.0, where heat protection effects were observed. At a temperature above 60 degrees C, simple deactivation is a suitable model. The results suggest that alpha-galactosidase conformation and heat stability are directly related.

Navigational choice between reversal and curve during acidic pH avoidance behavior in Caenorhabditis elegans.

PubMed

Wakabayashi, Tokumitsu; Sakata, Kazumi; Togashi, Takuya; Itoi, Hiroaki; Shinohe, Sayaka; Watanabe, Miwa; Shingai, Ryuzo

2015-11-19

Under experimental conditions, virtually all behaviors of Caenorhabditis elegans are achieved by combinations of simple locomotion, including forward, reversal movement, turning by deep body bending, and gradual shallow turning. To study how worms regulate these locomotion in response to sensory information, acidic pH avoidance behavior was analyzed by using worm tracking system. In the acidic pH avoidance, we characterized two types of behavioral maneuvers that have similar behavioral sequences in chemotaxis and thermotaxis. A stereotypic reversal-turn-forward sequence of reversal avoidance caused an abrupt random reorientation, and a shallow gradual turn in curve avoidance caused non-random reorientation in a less acidic direction to avoid the acidic pH. Our results suggest that these two maneuvers were each triggered by a distinct threshold pH. A simulation study using the two-distinct-threshold model reproduced the avoidance behavior of the real worm, supporting the presence of the threshold. Threshold pH for both reversal and curve avoidance was altered in mutants with reduced or enhanced glutamatergic signaling from acid-sensing neurons. C. elegans employ two behavioral maneuvers, reversal (klinokinesis) and curve (klinotaxis) to avoid acidic pH. Unlike the chemotaxis in C. elegans, reversal and curve avoidances were triggered by absolute pH rather than temporal derivative of stimulus concentration in this behavior. The pH threshold is different between reversal and curve avoidance. Mutant studies suggested that the difference results from a differential amount of glutamate released from ASH and ASK chemosensory neurons.

A continuous-flow, high-throughput, high-pressure parahydrogen converter for hyperpolarization in a clinical setting.

PubMed

Hövener, Jan-Bernd; Bär, Sébastien; Leupold, Jochen; Jenne, Klaus; Leibfritz, Dieter; Hennig, Jürgen; Duckett, Simon B; von Elverfeldt, Dominik

2013-02-01

Pure parahydrogen (pH(2) ) is the prerequisite for optimal pH(2) -based hyperpolarization experiments, promising approaches to access the hidden orders of magnitude of MR signals. pH(2) production on-site in medical research centers is vital for the proliferation of these technologies in the life sciences. However, previously suggested designs do not meet our requirements for safety or production performance (flow rate, pressure or enrichment). In this article, we present the safety concept, design and installation of a pH(2) converter, operated in a clinical setting. The apparatus produces a continuous flow of four standard liters per minute of ≈98% enriched pH(2) at a pressure maximum of 50 bar. The entire production cycle, including cleaning and cooling to 25 K, takes less than 5 h, only ≈45 min of which are required for actual pH(2) conversion. A fast and simple quantification procedure is described. The lifetimes of pH(2) in a glass vial and aluminum storage cylinder are measured to be T(1C) (glass vial) =822 ± 29 min and T(1C) (Al cylinder) =129 ± 36 days, thus providing sufficiently long storage intervals and allowing the application of pH(2) on demand. A dependence of line width on pH(2) enrichment is observed. As examples, (1) H hyperpolarization of pyridine and (13) C hyperpolarization of hydroxyethylpropionate are presented. Copyright © 2012 John Wiley & Sons, Ltd.

Tested Demonstrations.

ERIC Educational Resources Information Center

Gilbert, George L., Ed.

1986-01-01

Outlines a simple, inexpensive way of demonstrating electroplating using the reaction between nickel ions and copper metal. Explains how to conduct a demonstration of the electrolysis of water by using a colored Na2SO4 solution as the electrolyte so that students can observe the pH changes. (TW)

Techniques for Teachers Section

ERIC Educational Resources Information Center

Tait, A., Ed.

1973-01-01

Includes a simple technique to demonstrate Millikan's oil drop experiment, an environmental studies experiment to measure dissolved oxygen in water samples, and a technique to demonstrate action-reaction. Science materials described are the Pol-A-Star Tomiscope, Nuffield chemistry film loops, air pucks and pH meters. (JR)

Curcumin-Eudragit® E PO solid dispersion: A simple and potent method to solve the problems of curcumin.

PubMed

Li, Jinglei; Lee, Il Woo; Shin, Gye Hwa; Chen, Xiguang; Park, Hyun Jin

2015-08-01

Using a simple solution mixing method, curcumin was dispersed in the matrix of Eudragit® E PO polymer. Water solubility of curcumin in curcumin-Eudragit® E PO solid dispersion (Cur@EPO) was greatly increased. Based on the results of several tests, curcumin was demonstrated to exist in the polymer matrix in amorphous state. The interaction between curcumin and the polymer was investigated through Fourier transform infrared spectroscopy and (1)H NMR which implied that OH group of curcumin and carbonyl group of the polymer involved in the H bonding formation. Cur@EPO also provided protection function for curcumin as verified by the pH challenge and UV irradiation test. The pH value influenced curcumin release profile in which sustained release pattern was revealed. Additionally, in vitro transdermal test was conducted to assess the potential of Cur@EPO as a vehicle to deliver curcumin through this alternative administration route. Copyright © 2015 Elsevier B.V. All rights reserved.

Local pH oscillations witness autocatalytic self-organization of biomorphic nanostructures

NASA Astrophysics Data System (ADS)

Montalti, M.; Zhang, G.; Genovese, D.; Morales, J.; Kellermeier, M.; García-Ruiz, J. M.

2017-02-01

Bottom-up self-assembly of simple molecular compounds is a prime pathway to complex materials with interesting structures and functions. Coupled reaction systems are known to spontaneously produce highly ordered patterns, so far observed in soft matter. Here we show that similar phenomena can occur during silica-carbonate crystallization, the emerging order being preserved. The resulting materials, called silica biomorphs, exhibit non-crystallographic curved morphologies and hierarchical textures, much reminiscent of structural principles found in natural biominerals. We have used a fluorescent chemosensor to probe local conditions during the growth of such self-organized nanostructures. We demonstrate that the pH oscillates in the local microenvironment near the growth front due to chemical coupling, which becomes manifest in the final mineralized architectures as intrinsic banding patterns with the same periodicity. A better understanding of dynamic autocatalytic crystallization processes in such simple model systems is key to the rational development of advanced materials and to unravel the mechanisms of biomineralization.

Achieving pH control in microalgal cultures through fed-batch addition of stoichiometrically-balanced growth media

PubMed Central

2013-01-01

Background Lack of accounting for proton uptake and secretion has confounded interpretation of the stoichiometry of photosynthetic growth of algae. This is also problematic for achieving growth of microalgae to high cell concentrations which is necessary to improve productivity and the economic feasibility of commercial-scale chemical production systems. Since microalgae are capable of consuming both nitrate and ammonium, this represents an opportunity to balance culture pH based on a nitrogen feeding strategy that does not utilize gas-phase CO2 buffering. Stoichiometry suggests that approximately 36 weight%N-NH4+ (balance nitrogen as NO3-) would minimize the proton imbalance and permit high-density photoautotrophic growth as it does in higher plant tissue culture. However, algal media almost exclusively utilize nitrate, and ammonium is often viewed as ‘toxic’ to algae. Results The microalgae Chlorella vulgaris and Chlamydomonas reinhardtii exclusively utilize ammonium when both ammonium and nitrate are provided during growth on excess CO2. The resulting proton imbalance from preferential ammonium utilization causes the pH to drop too low to sustain further growth when ammonium was only 9% of the total nitrogen (0.027 gN-NH4+/L). However, providing smaller amounts of ammonium sequentially in the presence of nitrate maintained the pH of a Chlorella vulgaris culture for improved growth on 0.3 gN/L to 5 gDW/L under 5% CO2 gas-phase supplementation. Bioreactor pH dynamics are shown to be predictable based on simple nitrogen assimilation as long as there is sufficient CO2 availability. Conclusions This work provides both a media formulation and a feeding strategy with a focus on nitrogen metabolism and regulation to support high-density algal culture without buffering. The instability in culture pH that is observed in microalgal cultures in the absence of buffers can be overcome through alternating utilization of ammonium and nitrate. Despite the highly regulated array of nitrogen transporters, providing a nitrogen source with a balanced degree of reduction minimizes pH fluctuations. Understanding and accommodating the behavior of nitrogen utilization in microalgae is key to avoiding ‘culture crash’ and reliance on gas phase CO2 buffering, which becomes both ineffective and cost-prohibitive for commercial-scale algal culture. PMID:23651806

Photonic crystal fiber interferometric pH sensor based on polyvinyl alcohol/polyacrylic acid hydrogel coating.

PubMed

Hu, Pengbing; Dong, Xinyong; Wong, Wei Chang; Chen, Li Han; Ni, Kai; Chan, Chi Chiu

2015-04-01

We present a simple photonic crystal fiber interferometer (PCFI) that operates in reflection mode for pH measurement. The sensor is made by coating polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel onto the surface of the PCFI, constructed by splicing a stub of PCF at the distal end of a single-mode fiber with its free end airhole collapsed. The experimental results demonstrate a high average sensitivity of 0.9 nm/pH unit for the 11 wt.% PVA/PAA coated sensor in the pH range from 2.5 to 6.5. The sensor also displays high repeatability and stability and low cross-sensitivity to temperature. Fast, reversible rise and fall times of 12 s and 18 s, respectively, are achieved for the sensor time response.

Experimental and theoretical investigation of the stability of stepwise pH gradients in continuous flow electrophoresis

NASA Technical Reports Server (NTRS)

Kuhn, Reinhard; Wagner, Horst; Mosher, Richard A.; Thormann, Wolfgang

1987-01-01

Isoelectric focusing in the continuous flow mode can be more quickly and economically performed by admitting a stepwise pH gradient composed of simple buffers instead of uniform mixtures of synthetic carrier ampholytes. The time-consuming formation of the pH gradient by the electric field is thereby omitted. The stability of a three-step system with arginine - morpholinoethanesulfonic acid/glycylglycine - aspartic acid is analyzed theoretically by one-dimensional computer simulation as well as experimentally at various flow rates in a continuous flow apparatus. Excellent agreement between experimental and theoretical data was obtained. This metastable configuration was found to be suitable for focusing of proteins under continuous flow conditions. The influence of various combinations of electrolytes and membranes between electrophoresis chamber and electrode compartments is also discussed.

Size control of Au NPs supported by pH operation

NASA Astrophysics Data System (ADS)

Ichiji, Masumi; Akiba, Hiroko; Hirasawa, Izumi

2017-07-01

Au NPs are expected to become useful functional particles, as particle gun used for plant gene transfer and also catalysts. We have studied PSD (particle size distribution) control of Au NPs by reduction crystallization. Previous study found out importance of seeds policy and also feeding profile. In this paper, effect of pH in the reduction crystallization was investigated to clarify the possibility of Au NPs PSD control by pH operation and also their growth process. Au NPs of size range 10-600 nm were obtained in single-jet system using ascorbic acid (AsA) as a reducing agent with adjusting pH of AsA. Au NPs are found to grow in the process of nucleation, agglomeration, agglomeration growth and surface growth. Au NPs tend to grow by agglomeration and become larger size in lower pH regions, and to grow only by surface growth and become smaller size in higher pH regions.

Harnessing the Effect of pH on Lipid Production in Batch Cultures of Yarrowia lipolytica SKY7.

PubMed

Kuttiraja, Mathiazhakan; Dhouha, Ayed; Tyagi, Rajeshwar Dayal

2018-04-01

The objective of this research was to investigate the kinetics of lipid production by Yarrowia lipolytica SKY7 in the crude glycerol-supplemented media with and without the control of pH. Lipid and citric acid production were improved with the pH control condition. There was no significant difference observed in the biomass concentration with or without the pH control. In the pH-controlled experiments, the biomass and lipid concentration reached 18 and 7.78 g/L, (45.5% w/w), respectively, with lipid yield (Yp/s) of 0.179 g/g at 60 h of fermentation. The lipid production was directly correlated with growth and the process was defined as growth associated. After 60 h of fermentation, the lipid degradation was noticed in the pH-controlled reactor whereas it occurred after 84 h in the pH-uncontrolled reactor. Apart from lipid, citric acid was produced as the major extracellular product in both fermentations but the much lower concentration in uncontrolled pH. Based on the experimental results, it is evident that controlling the pH will enhance the lipid production by 15% compared to pH-uncontrolled fermentation.

Assessment of pH shock as a method for controlling sulfide and methane formation in pressure main sewer systems.

PubMed

Gutierrez, Oriol; Sudarjanto, Gatut; Ren, Guo; Ganigué, Ramon; Jiang, Guangming; Yuan, Zhiguo

2014-01-01

Caustic dosing to raise pH above 10.0 for short periods (hours) is often used by water utilities for controlling sulfide formation in sewers. However the effectiveness of this strategy is rarely reported and the impact of pH level and exposure time on the effectiveness is largely unknown. The effectiveness of this strategy under various pH levels (10.5-12.5) and exposure time (0.5-6.0 h) in controlling sulfide and methane production was evaluated in laboratory scale anaerobic sewer reactors and then in a real sewer system. Laboratory studies showed that the sulfide production rate of the laboratory sewer biofilm was reduced by 70-90% upon the completion of the pH shock, while the methane production rate decreased by 95-100%. It took approximately one week for the sulfate-reducing activity to recover to normal levels. In comparison, the methanogenic activities recovered to only about 10% in 4 weeks. The slow recovery is explained by the substantially loss of cell viability upon pH shocks, which recovered slowly after the shocks. Laboratory studies further revealed that a pH level of 10.5 for 1-2 h represent cost-effective conditions for the pH shock treatment. However, field trials showed a higher pH (11.5) and larger dosing times are needed due to the pH decreases along the sewer line and at the two ends of the caustic-receiving wastewater slugs due to dilution. To have effective sulfide and methane control, it is important to ensure effective conditions (pH > 10.5 and duration >1-2 h) for the entire sewer line. Copyright © 2013 Elsevier Ltd. All rights reserved.

Morphology-controllable growth of GdVO4:Eu3+ nano/microstructures for an optimum red luminescence

NASA Astrophysics Data System (ADS)

Yang, Liusai; Li, Guangshe; Zhao, Minglei; Zheng, Jing; Guan, Xiangfeng; Li, Liping

2012-06-01

Chemically tailoring microstructures for an optimum red luminescence is a subject at the forefront of many disciplines, which still remains a challenge due to a poor knowledge about the roles of defects in structures. In this work, GdVO4 :Eu3+ nano/microstructures of different morphologies, including tomato-like, cookie-circle-like, and ellipsoidal-like nanoparticles, and microspheroids were synthesized via a simple hydrothermal route using trisodium citrate as a capping agent. During the growth processes, the types of vanadyl ions were adjusted by varying pH value to control the morphologies and nano/microstructures with the help of trisodium citrate. The possible mechanisms for the growth processes into diverse morphologies are presented. Further, a systematic study on defect characteristics pertinent to these diverse morphologies has been explored to achieve an optimum red luminescence. The ability is clearly shown to generate different nano/microstructures of diverse morphologies and varied defect concentrations, which provides a great opportunity for morphological control in tailoring the red luminescence property for many technological applications.

Morphology-controllable growth of GdVO4:Eu3+ nano/microstructures for an optimum red luminescence.

PubMed

Yang, Liusai; Li, Guangshe; Zhao, Minglei; Zheng, Jing; Guan, Xiangfeng; Li, Liping

2012-06-22

Chemically tailoring microstructures for an optimum red luminescence is a subject at the forefront of many disciplines, which still remains a challenge due to a poor knowledge about the roles of defects in structures. In this work, GdVO(4) :Eu(3+) nano/microstructures of different morphologies, including tomato-like, cookie-circle-like, and ellipsoidal-like nanoparticles, and microspheroids were synthesized via a simple hydrothermal route using trisodium citrate as a capping agent. During the growth processes, the types of vanadyl ions were adjusted by varying pH value to control the morphologies and nano/microstructures with the help of trisodium citrate. The possible mechanisms for the growth processes into diverse morphologies are presented. Further, a systematic study on defect characteristics pertinent to these diverse morphologies has been explored to achieve an optimum red luminescence. The ability is clearly shown to generate different nano/microstructures of diverse morphologies and varied defect concentrations, which provides a great opportunity for morphological control in tailoring the red luminescence property for many technological applications.

Balancing the intermolecular forces in peptide amphiphiles for controlling self-assembly transitions.

PubMed

Buettner, C J; Wallace, A J; Ok, S; Manos, A A; Nicholl, M J; Ghosh, A; Tweedle, M F; Goldberger, J E

2017-06-21

While the influence of alkyl chain length and headgroup size on self-assembly behaviour has been well-established for simple surfactants, the rational control over the pH- and concentration-dependent self-assembly behaviour in stimuli responsive peptides remains an elusive goal. Here, we show that different amphiphilic peptides can have similar self-assembly phase diagrams, providing the relative strengths of the attractive and repulsive forces are balanced. Using palmitoyl-YYAAEEEEK(DO3A:Gd)-NH 2 and palmitoyl-YAAEEEEK(DO3A:Gd)-NH 2 as controls, we show that reducing hydrophobic attractive forces through fewer methylene groups in the alkyl chain will lead to a similar self-assembly phase diagram as increasing the electrostatic repulsive forces via the addition of a glutamic acid residue. These changes allow creation of self-assembled MRI vehicles with slightly different micelle and nanofiber diameters but with minimal changes in the spin-lattice T 1 relaxivity. These findings reveal a powerful strategy to design self-assembled vehicles with different sizes but with similar self-assembly profiles.

Improving the storage stability of Bifidobacterium breve in low pH fruit juice.

PubMed

Saarela, M; Alakomi, H L; Mättö, J; Ahonen, A M; Puhakka, A; Tynkkynen, S

2011-09-01

Bifidobacterial food applications are limited since bifidobacteria are sensitive to e.g. acidic conditions prevalent in many food matrices. The aim of the present study was to investigate whether a low pH selection step alone or combined to UV mutagenesis could improve the viability of an acid sensitive Bifidobacterium strain, B. breve 99, in low pH food matrices. Furthermore, the potential of carriers and an oat fibre preparation to further improve the stability was studied. The best performing low pH tolerant variants in the present study were generated by UV-mutagenesis with 70-700μJ/cm(2) followed by incubation in growth medium at pH 4.5. The most promising variants regarding the low pH tolerance showed, in repeated tests with cells grown without pH control, about one Log-value better survival in pH 3.8 fruit juice after one week storage at 4°C compared to wild-type B. breve 99. Cells grown with pH control, PDX formulated and then frozen showed poorer viability in low pH fruit juice than cells grown with no pH control. For frozen concentrates pH 3.8 was too stressful and no or small differences between the variants and the wild-type strain were seen. The differences detected at pH 3.8 with the cells grown without pH control were also seen with the frozen concentrates at pH 4.5. Some improvement in the stability could be achieved by using a combination of trehalose, vitamin C and PDX as a freezing carrier material, whereas a significant improvement in the stability was seen when oat fibre was added into the fruit juice together with the frozen cells. Due to the initial very poor fruit juice tolerance of B. breve 99 the obtained improvement in the stability was not enough for commercial applications. However, the same methods could be applied to initially better performing strains to further improve their stability in the fruit juice. Copyright © 2010 Elsevier B.V. All rights reserved.

pH and Organic Carbon Dose Rates Control Microbially Driven Bioremediation Efficacy in Alkaline Bauxite Residue.

PubMed

Santini, Talitha C; Malcolm, Laura I; Tyson, Gene W; Warren, Lesley A

2016-10-18

Bioremediation of alkaline tailings, based on fermentative microbial metabolisms, is a novel strategy for achieving rapid pH neutralization and thus improving environmental outcomes associated with mining and refining activities. Laboratory-scale bioreactors containing bauxite residue (an alkaline, saline tailings material generated as a byproduct of alumina refining), to which a diverse microbial inoculum was added, were used in this study to identify key factors (pH, salinity, organic carbon supply) controlling the rates and extent of microbially driven pH neutralization (bioremediation) in alkaline tailings. Initial tailings pH and organic carbon dose rates both significantly affected bioremediation extent and efficiency with lower minimum pHs and higher extents of pH neutralization occurring under low initial pH or high organic carbon conditions. Rates of pH neutralization (up to 0.13 mM H + produced per day with pH decreasing from 9.5 to ≤6.5 in three days) were significantly higher in low initial pH treatments. Representatives of the Bacillaceae and Enterobacteriaceae, which contain many known facultative anaerobes and fermenters, were identified as key contributors to 2,3-butanediol and/or mixed acid fermentation as the major mechanism(s) of pH neutralization. Initial pH and salinity significantly influenced microbial community successional trajectories, and microbial community structure was significantly related to markers of fermentation activity. This study provides the first experimental demonstration of bioremediation in bauxite residue, identifying pH and organic carbon dose rates as key controls on bioremediation efficacy, and will enable future development of bioreactor technologies at full field scale.

Effect of External Use of Sesame Oil in the Prevention of Chemotherapy-Induced Phlebitis

PubMed Central

Nekuzad, Nilufar; Ashke Torab, Tahereh; Mojab, Faraz; Alavi-Majd, Hamid; Azadeh, Payam; Ehtejab, Gholamreza

2012-01-01

Intravenous chemotherapy is an important mean for the treatment of cancers. Infusion phlebitis (Ph) is a common and acute complication of chemotherapy. The frequency of Ph is about 70% in patients undergoing chemotherapeutic management. It can induce the pain, increase the risk of thrombophlebitis, lead to incomplete follow-up, and thereby, affect the patient’s health status. Respecting the great importance of these issues, it is essential to prevent Ph. This study conducted to determine the effect of external use of Sesame Oil (SO) in the prevention of Ph. Sixty patients with colon or rectum cancer, who admitted for chemotherapeutic management, enrolled in clinical trial and were randomly divided into two equal groups: Control and Intervention. Ten drops of SO was applied twice a day for 14 days externally in intervention group, whereas the control group received nothing. Incidence and grade of Ph was measured in both groups. Data was analyzed through independent t-test, Χ2, Fisher’s exact test, Mann-Whitney, and Lagrange survival using SPSS 16. The incidence of Ph was 10% and 80% in intervention group and control group, respectively.There was a significant difference between two groups (p < 0.05). Ph was 8 times more frequent in control group (R R = 8; AR R = 70%). In addition, there was statistically significant difference between the grade and incidence of Ph with SO and control group (p < 0.05). According to these results, it seems that external use of SO is effective, safe and well-tolerated for prophylaxis from Ph. Therefore, it can be suggested as a selected prevention method for reducing the complication. PMID:24250538

Gold nanoparticles prepared by electro-exploding wire technique in aqueous solutions

NASA Astrophysics Data System (ADS)

Kumar, Lalit; Kapoor, Akanksha; Meghwal, Mayank; Annapoorni, S.

2016-05-01

This article presents an effective approach for the synthesis of Au nanoparticles via an environmentally benevolent electro-exploding wire (EEW) technique. In this process, Au nanoparticles evolve through the plasma generated from the parent Au metal. Compared to other typical chemical methods, electro-exploding wire technique is a simple and economical technique which normally operates in water or organic liquids under ambient conditions. Efficient size control was achieved using different aqueous medium like (1mM) NaCl, deionized water and aqueous solution of sodium hydroxide (NaOH, pH 9.5) using identical electro-exploding conditions. The gold nanoparticles exhibited the UV-vis absorption spectrum with a maximum absorption band at 530 nm, similar to that of gold nanoparticles chemically prepared in a solution. The mechanism of size variation of Au nanoparticles is also proposed. The results obtained help to develop methodologies for the control of EEW based nanoparticle growth and the functionalization of nanoparticle surfaces by specific interactions.

Harnessing photochemical internalization with dual degradable nanoparticles for combinatorial photo-chemotherapy

NASA Astrophysics Data System (ADS)

Pasparakis, George; Manouras, Theodore; Vamvakaki, Maria; Argitis, Panagiotis

2014-04-01

Light-controlled drug delivery systems constitute an appealing means to direct and confine drug release spatiotemporally at the site of interest with high specificity. However, the utilization of light-activatable systems is hampered by the lack of suitable drug carriers that respond sharply to visible light stimuli at clinically relevant wavelengths. Here, a new class of self-assembling, photo- and pH-degradable polymers of the polyacetal family is reported, which is combined with photochemical internalization to control the intracellular trafficking and release of anticancer compounds. The polymers are synthesized by simple and scalable chemistries and exhibit remarkably low photolysis rates at tunable wavelengths over a large range of the spectrum up to the visible and near infrared regime. The combinational pH and light mediated degradation facilitates increased therapeutic potency and specificity against model cancer cell lines in vitro. Increased cell death is achieved by the synergistic activity of nanoparticle-loaded anticancer compounds and reactive oxygen species accumulation in the cytosol by simultaneous activation of porphyrin molecules and particle photolysis.

INFLUENCE OF MINERAL FORM, MATRIX CONCENTRATION AND PH ON IN-VITRO EXTRACTABILITY

EPA Science Inventory

Due to extensive resources required to conduct bioavailability studies, there is a veritable need for a laboratory in-vitro extraction procedure that yields a strong correlation to actual animal results that is simple to conduct and relatively rapid in data productivity. Research...

Enzyme Activity Experiments Using a Simple Spectrophotometer

ERIC Educational Resources Information Center

Hurlbut, Jeffrey A.; And Others

1977-01-01

Experimental procedures for studying enzyme activity using a Spectronic 20 spectrophotometer are described. The experiments demonstrate the effect of pH, temperature, and inhibitors on enzyme activity and allow the determination of Km, Vmax, and Kcat. These procedures are designed for teaching large lower-level biochemistry classes. (MR)

Phenotypic and Functional Analysis of Human SLC26A6 Variants in Patients With Familial Hyperoxaluria and Calcium Oxalate Nephrolithiasis

PubMed Central

Monico, Carla G.; Weinstein, Adam; Jiang, Zhirong; Rohlinger, Audrey L.; Cogal, Andrea G.; Bjornson, Beth B.; Olson, Julie B.; Bergstralh, Eric J.; Milliner, Dawn S.; Aronson, Peter S.

2008-01-01

Background Urinary oxalate is a major risk factor for calcium oxalate stones. Marked hyperoxaluria arises from mutations in two separate loci, AGXT and GRHPR, the causes of primary hyperoxaluria (PH) types 1 and 2, respectively. Studies of null Slc26a6 (−/−) mice have revealed a phenotype of hyperoxaluria, hyperoxalemia and calcium oxalate urolithiasis, leading to the hypothesis that SLC26A6 mutations may cause or modify hyperoxaluria in humans. Study Design Cross-sectional, case-control. Setting & Participants Cases were recruited from the International Primary Hyperoxaluria Registry. Control DNA samples were from a pool of adult subjects who identified themselves as being in good health. Predictor PH1, PH2, non-PH1/PH2 genotypes in cases. Outcomes & Measures Homozygosity or compound heterozygosity for SLC26A6 variants. Functional expression of oxalate transport in Xenopus oocytes. Results A total of 80 PH1, 6 PH2, 8 non-PH1/PH2 and 96 control samples were available for SLC26A6 screening. A rare variant, c.487C>T (p.Pro163Ser) was detected solely in one non-PH1/PH2 pedigree but this variant failed to segregate with hyperoxaluria, and functional studies of oxalate transport in Xenopus oocytes revealed no transport defect. No other rare variant was identified specifically in non-PH1/PH2. Six additional missense variants were detected in controls and in cases. Of these, c.616G>A (p.Val206Met) was most common (11%), and showed a 30% reduction in oxalate transport. To test p.Val206Met as a potential modifier of hyperoxaluria, we extended screening to PH1 and PH2. Heterozygosity for this variant did not affect plasma or urine oxalate in this population. Limitations We did not have a sufficient number of cases to determine whether homozygosity for p.Val206Met might significantly affect urine oxalate. Conclusions SLC26A6 was effectively ruled out as the disease gene in this non-PH1/PH2 cohort. Taken together, our studies are the first to identify and characterize SLC26A6 variants in hyperoxaluria. Phenotypic and functional analysis excluded a significant effect of identified variants on oxalate excretion. PMID:18951670

Hydrogels of polyvinylpyrrolidone (PVP) and poly(acrylic acid) (PAA) synthesized by radiation-induced crosslinking of homopolymers

NASA Astrophysics Data System (ADS)

Kadłubowski, Sławomir; Henke, Artur; Ulański, Piotr; Rosiak, Janusz M.

2010-03-01

pH-sensitive PVP-PAA hydrogels have been prepared by electron-beam-induced irradiation at pH close to pKa of carboxylic groups. Protonation of these groups promoted the formation of hydrogen bonds between the PAA and PVP segments within the crosslinked structure and caused interpolymer complex formation. To demonstrate possible future application of such gels, we tested them as simple chemical detectors. When loaded with glucose oxidase, the PAA-PVP gel's turbidity and shrinkage was triggered by the presence of glucose due to a drop in pH caused by the enzymatic reaction.

Rapid methods for extraction and concentration of poliovirus from oyster tissues.

PubMed

Richards, G P; Goldmintz, D; Green, D L; Babinchak, J A

1982-12-01

A procedure is discussed for the extraction of poliovirus from oyster meats by modification of several enterovirus extraction techniques. The modified method uses meat extract and Cat-Floc, a polycationic electrolyte, for virus extraction and concentration. Virus recovery from inoculated oyster homogenates is 93-120%. Adsorption of viruses to oyster proteins by acidification of homogenates does not affect virus recovery. Elution of viruses from oyster proteins appears more efficient at pH 9.5 than at pH 8.0. This technique is relatively simple, economical and requires only 2.5 h to complete the combined extraction and concentration procedure.

Proton mediated control of biochemical reactions with bioelectronic pH modulation

NASA Astrophysics Data System (ADS)

Deng, Yingxin; Miyake, Takeo; Keene, Scott; Josberger, Erik E.; Rolandi, Marco

2016-04-01

In Nature, protons (H+) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H+ channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H+ currents and H+ concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H+ between PdHx contacts and solution. The present transducer records bistable pH modulation from an “enzymatic flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. The transducer also controls bioluminescence from firefly luciferase by affecting solution pH.

Rain pH estimation based on the particulate matter pollutants and wet deposition study.

PubMed

Singh, Shweta; Elumalai, Suresh Pandian; Pal, Asim Kumar

2016-09-01

In forecasting of rain pH, the changes caused by particulate matter (PM) are generally neglected. In regions of high PM concentration like Dhanbad, the role of PM in deciding the rain pH becomes important. Present work takes into account theoretical prediction of rain pH by two methods. First method considers only acid causing gases (ACG) like CO2, SO2 and NOx in pH estimation, whereas, second method additionally accounts for effect of PM (ACG-PM). In order to predict the rain pH, site specific deposited dust that represents local PM was studied experimentally for its impact on pH of neutral water. After incorporation of PM correction factor, it was found that, rain pH values estimated were more representative of the observed ones. Fractional bias (FB) for the ACG-PM method reduced to values of the order of 10(-2) from those with order of 10(-1) for the ACG method. The study confirms neutralization of rain acidity by PM. On account of this, rain pH was found in the slightly acidic to near neutral range, despite of the high sulfate flux found in rain water. Although, the safer range of rain pH blurs the severity of acid rain from the picture, yet huge flux of acidic and other ions get transferred to water bodies, soil and ultimately to the ground water system. Simple use of rain pH for rain water quality fails to address the issues of its increased ionic composition due to the interfering pollutants and thus undermines severity of pollutants transferred from air to rain water and then to water bodies and soil. Copyright © 2016 Elsevier B.V. All rights reserved.

pH dependent silver nanoparticles releasing titanium implant: A novel therapeutic approach to control peri-implant infection.

PubMed

Dong, Yiwen; Ye, Hui; Liu, Yi; Xu, Lihua; Wu, Zuosu; Hu, Xiaohui; Ma, Jianfeng; Pathak, Janak L; Liu, Jinsong; Wu, Gang

2017-10-01

Peri-implant infection control is crucial for implant fixation and durability. Antimicrobial administration approaches to control peri-implant infection are far from satisfactory. During bacterial infection, pH level around the peri-implant surface decreases as low as pH 5.5. This change of pH can be used as a switch to control antimicrobial drug release from the implant surface. Silver nanoparticles (AgNPs) have broad-spectrum antimicrobial properties. In this study, we aimed to design a pH-dependent AgNPs releasing titania nanotube arrays (TNT) implant for peri-implant infection control. The nanotube arrays were fabricated on the surface of titanium implant as containers; AgNPs were grafted on TNT implant surface via a low pH-sensitive acetal linker (TNT-AL-AgNPs). SEM, TEM, AFM, FTIR as well as XPS data showed that AgNPs have been successfully linked to TNT via acetal linker without affecting the physicochemical characteristics of TNT. The pH 5.5 enhanced AgNPs release from TNT-AL-AgNPs implant compared with pH 7.4. AgNPs released at pH 5.5 robustly increased antimicrobial activities against gram-positive and gram-negative bacteria compared with AgNPs released at pH 7.4. TNT-AL-AgNPs implant enhanced osteoblast proliferation, differentiation, and did not affect osteoblast morphology in vitro. In conclusion, incorporation of AgNPs in TNT via acetal linker maintained the surface characteristics of TNT. TNT-AL-AgNPs implant was biocompatible to osteoblasts and showed osteoinductive properties. AgNPs were released from TNT-AL-AgNPs implant in high dose at pH 5.5, and this release showed strong antimicrobial properties in vitro. Therefore, this novel design of low pH-triggered AgNPs releasing TNT-AL-AgNPs could be an infection-triggered antimicrobial releasing implant model to control peri-implant infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of a control test to aid pH assessment of chemical eye injuries.

PubMed

Connor, A J; Severn, P

2009-11-01

Chemical burns of the eye represent 7.0%-9.9% of all ocular trauma. Initial management of ocular chemical injuries is irrigation of the eye and conjunctival sac until neutralisation of the tear surface pH is achieved.We present a case of alkali injury in which the raised tear film pH seemed to be unresponsive to irrigation treatment. Suspicion was raised about the accuracy of the litmus paper used to test the tear film pH. The error was confirmed by use of a control litmus pH test of the examining doctor's eyes. Errors in litmus paper pH measurement can occur because of difficulty in matching the paper with scale colours and drying of the paper, which produces a darker colour. A small tear film sample can also create difficulty in colour matching, whereas too large a sample can wash away pigment from the litmus paper. Samples measured too quickly after irrigation can result in a falsely neutral pH measurement. Use of faulty or inappropriate materials can also result in errors. We advocate the use of control litmus pH test in all patients. This would highlight errors in pH measurements and aid in the detection of the end point of irrigation.

Fabrication of Si nanopowder and application to hydrogen generation and photoluminescent material

NASA Astrophysics Data System (ADS)

Kobayashi, Yuki; Imamura, Kentaro; Matsumoto, Taketoshi; Kobayashi, Hikaru

2017-12-01

Si nanopowder is fabricated using the simple beads milling method. Fabricated Si nanopowder reacts with water in the neutral pH region between 7 and 9 to generate hydrogen. The hydrogen generation rate greatly increases with pH, while pH does not change after the hydrogen generation reaction. In the case of the reactions of Si nanopowder with strong alkaline solutions (eg pH13.9), 1600 mL hydrogen is generated from 1 g Si nanopowder in a short time (eg 15 min). When Si nanopowder is etched with HF solutions and immersed in ethanol, green photoluminescence (PL) is observed, and it is attributed to band-to-band transition of Si nanopowder. The Si nanopowder without HF etching in hexane shows blue PL. The PL spectra possess peaked structure, and it is attributed to vibronic bands of 9,10-dimethylantracene (DMA) in hexane solutions. The PL intensity is increased by more than 3,000 times by adsorption of DMA on Si nanopowder.

Oral pH in gastroesophageal reflux disease.

PubMed

Sujatha, S; Jalihal, Umesh; Devi, Yashoda; Rakesh, N; Chauhan, Pallavi; Sharma, Shivani

2016-05-01

The aim of this study is to compare surface pH in various parts of the oral cavity between patients with gastroesophageal reflux disease (GERD) and healthy controls. Using a flat pH meter sensor, fixed electrode pen type digital pH meter, oral pH levels were assessed at different mucosal sites among 34 GERD patients and 32 healthy controls. Salivary flow rates and buffering capacity were also assessed in them. A thorough oral examination was performed to screen for any oral and dental changes. A significantly lower pH of 6.65 ± 0.13 (mean ± SD) was found in the GERD group compared to control group 7.23 ± 0.12 (p < 0.05). Least pH was found in the floor of the mouth 6.594 ± 0.17 and highest in the lower labial mucosa among the GERD patients. Salivary flow rate and buffering capacity were low in these patients. Significant changes were noticed in the hard and soft tissues of the oral cavity among the GERD group. Oral mucosal pH is altered in GERD patients and may contribute to effects on the oral cavity.

Investigation of the adsorption mechanism of a peptide in reversed phase liquid chromatography, from pH controlled and uncontrolled solutions

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

Gritti, Fabrice; Guiochon, Georges A

2009-01-01

The single-component equilibrium adsorption of the tripeptide Leucyl-Leucyl-Leucine (LLL) on a high-efficiency Jupiter Proteo column (C{sub 12}) was investigated experimentally and modeled theoretically. The experimental equilibrium isotherms of LLL for adsorption on a C{sub 12} packing material from an aqueous solution of methanol (48%) and trifluoroacetic acid (0.1%) were measured by frontal analysis (FA). The FA measurements were done with two solutions, one in which the pH was controlled, the other in which it was not. Two solutions of LLL in the mobile phase were prepared (4.3 and 5.4 g/L) and their pH measured (2.94 and 2.88), respectively. The firstmore » solution was titrated with TFA to match the pH of the mobile phase (2.03), so its pH was controlled. The pH of the other solution was left uncontrolled. In both cases the isotherms could be modeled by a bi-Langmuir equation, a choice consistent with the bimodal affinity energy distribution (AED) obtained for LLL. The isotherm parameters derived from the inverse method (IM) of isotherm determination under controlled pH conditions (by fitting calculated profiles to experimental breakthrough profiles) are in a good agreement with those derived from the FA data. Under uncontrolled pH conditions, the application of IM suggests the coexistence of two different adsorption mechanisms. According to the isotherm parameters found by these three methods (FA, AED and IM), the C{sub 12}-bonded silica can adsorb around 500 and 70 g/L of LLL under controlled and uncontrolled pH conditions, respectively. The adsorption of LLL on the C{sub 12} material strongly depends on the pH of the mobile phase and on the quantity of TFA added, which plays the role of an ion-pairing agent.« less

[Effects of dissolved oxygen and pH on Candida utilis batch fermentation of glutathione].

PubMed

Wei, Gong-Yuan; Li, Yin; Du, Guo-Cheng; Chen, Jian

2003-11-01

The effects of dissolved oxygen (DO) and pH on glutathione batch fermentation by Candida utilis WSH-02-08 in a 7 liters stirred fermentor were investigated. It was shown that DO concentration is an important factor in glutathione production. With the initial glucose concentration of 30 g/L and a 5 L/min air flow rate, and the agitation rate less than 250 r/min, the DO concentration was not sufficient to satisfy the oxygen requirement during the fermentation. With an agitation rate of more than 300 r/min, the cell growth and glutathione production were enhanced significantly, with the dry cell mass and glutathione production were 20% and 25% higher than that at 200 r/min. When C. utilis WSH 02-08 was cultivated in a batch process without pH control, cell growth and glutathione production were inhibited, likely due to a dramatic decrease in the pH. Intracellular glutathione leakages were observed when the pH was 1.5 or less. To assess the effect of pH on glutathione production, six batch processes controlled at pH 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5 were conducted. The yield was highest at pH 5.5, when the dry cell mass and yield were 27% and 95% respectively higher than fermentation without pH control. The maximal intracellular glutathione content (2.15 %) was also achieved at the pH. To improve our understandings on the effect of pH on the batch glutathione production, a modified Logistic equation and Luedeking-Piret equation were used to simulate cell growth and glutathione production, respectively, under different pH. Based on the parameters obtained by the nonlinear estimation, kinetic analysis was performed to elucidate the effect of pH on the batch glutathione production. The process controlled at pH 5.5 was proven to be the best due to the higher value of K(I) (substrate inhibitory constant in the Logistic equation), lower value of a and higher value of beta (slope and intercept in the Luedeking-Piret equation, respectively).

A synthetic multifunctional mammalian pH sensor and CO2 transgene-control device.

PubMed

Ausländer, David; Ausländer, Simon; Charpin-El Hamri, Ghislaine; Sedlmayer, Ferdinand; Müller, Marius; Frey, Olivier; Hierlemann, Andreas; Stelling, Jörg; Fussenegger, Martin

2014-08-07

All metabolic activities operate within a narrow pH range that is controlled by the CO2-bicarbonate buffering system. We hypothesized that pH could serve as surrogate signal to monitor and respond to the physiological state. By functionally rewiring the human proton-activated cell-surface receptor TDAG8 to chimeric promoters, we created a synthetic signaling cascade that precisely monitors extracellular pH within the physiological range. The synthetic pH sensor could be adjusted by organic acids as well as gaseous CO2 that shifts the CO2-bicarbonate balance toward hydrogen ions. This enabled the design of gas-programmable logic gates, provided remote control of cellular behavior inside microfluidic devices, and allowed for CO2-triggered production of biopharmaceuticals in standard bioreactors. When implanting cells containing the synthetic pH sensor linked to production of insulin into type 1 diabetic mice developing diabetic ketoacidosis, the prosthetic network automatically scored acidic pH and coordinated an insulin expression response that corrected ketoacidosis. Copyright © 2014 Elsevier Inc. All rights reserved.

Mathematical model for internal pH control in immobilized enzyme particles

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

Liou, J.K.; Rousseau, I.

A mathematical model has been developed for the internal pH control in immobilized enzyme particles. This model describes the kinetics of a coupled system of two enzymes, immobilized in particles of either planar, cylindrical, or spherical shape. The enzyme kinetics are assumed to be of a mixed type, including Michaelis-Menten kinetics, uncompetitive substrate inhibition, and competitive and noncompetitive product inhibition. In a case study we have considered the enzyme combination urease and penicillin acylase, whose kinetics are coupled through the pH dependence of the kinetic parameters. The hydrolysis of urea by urease yields ammonia and carbon dioxide, whereas benzylpenicillin (Pen-G)more » is converted to 6-animo penicillanic acid and phenyl acetic acid by penicillin acylase. The production of acids by the latter enzyme will cause a decrease in pH. Because of the presence of the ammonia-carbon dioxide system, however, the pH may be kept under control. In order to obtain information about the optimum performance of this enzymatic pH controller, we have computed the effectiveness factor and the conversion in a CSTR at different enzyme loadings. The results of the computer simulations indicate that a high conversion of Pen-G may be achieved (80-90%) at bulk pH values of about 7.5 - 8. 27 references.« less

Effect of pH on ethanol-type acidogenic fermentation of fruit and vegetable waste.

PubMed

Wu, Yuanyuan; Wang, Cuiping; Zheng, Mingyue; Zuo, Jiane; Wu, Jing; Wang, Kaijun; Yang, Boqiong

2017-02-01

The aim of this study was to investigate the possibility and optimal controlling strategy for ethanol-type acidogenic fermentation of fruit and vegetable waste by mixed microbial cultures. Four continuous stirred tank reactors (CSTR) were operated at various pHs (4.0, 5.0, 5.5, and 6.0) with an organic loading rate of 13gVS/(Ld) and hydraulic retention time of 3d. Butyrate-type fermentation was observed at pH 5.0, 5.5, and 6.0. Conversely, at pH 4.0, ethanol-type fermentation was observed with a high mass concentration and proportion (of total fermentative products) of ethanol, which were 6.7g/L and 88.8%, respectively. However, the total concentration of ethanol-type fermentative products substantially decreased from days 22-25. The optimal pH of ethanol-type fermentative microorganisms was investigated by using batch experiments with pH controlled at 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, and 7.0 and results showed that the maximum ethanol concentration and relatively highest acidogenic rate were found at pH of 5.5. The pH in the long term CSTR was changed from 4.0 to 5.5 to improve ethanol-type fermentation and results showed that ethanol-type fermentation was improved temporarily, however, was followed by the reappearance of butyrate-type fermentation. In addition, ethanol-type fermentation recovered once more when pH was reverted to 4.0. Therefore, the results of this study suggest that a process of dynamic, sequenced pH control with the order pH 4.0, 5.5 and 4.0 might be a feasible controlling strategy for continuous and stable ethanol-type fermentation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Alkaline and ultrasonic dissolution of biological materials for trace silicon determination

PubMed Central

Viveros, Robert D.; Liberman, Alexander; Trogler, William C.; Kummel, Andrew C.

2015-01-01

A simple method for trace elemental determination in biological tissue has been developed. Novel nanomaterials with biomedical applications necessitate the determination of the in vivo fate of the materials to understand their toxicological profile. Hollow iron-doped calcined silica nanoshells have been used as a model to demonstrate that potassium hydroxide and bath sonication at 50 °C can extract elements from alkaline-soluble nanomaterials. After alkali digestion, nitric acid is used to adjust the pH into a suitable range for analysis using techniques such as inductively coupled plasma optical emission spectrometry which require neutral or acidic analytes. In chicken liver phantoms injected with the nanoshells, 96% of the expected silicon concentration was detected. This value was in good agreement with the 94% detection efficiency of nanoshells dissolved in aqueous solution as a control for potential sample matrix interference. Nanoshell detection was further confirmed in a mouse 24 h after intravenous administration; the measured silica above baseline was 35 times greater or more than the standard deviations of the measurements. This method provides a simple and accurate means to quantify alkaline-soluble nanomaterials in biological tissue. PMID:25909037

Construction and characterization of a pure protein hydrogel for drug delivery application.

PubMed

Xu, Xu; Xu, ZhaoKang; Yang, XiaoFeng; He, YanHao; Lin, Rong

2017-02-01

Injectable hydrogels have a variety of applications, including regenerative medicine, tissue engineering and controlled drug delivery. In this paper, we reported on a pure protein hydrogel based on tetrameric recombinant proteins for the potential drug delivery application. This protein hydrogel was formed instantly by simply mixing two recombinant proteins (ULD-TIP1 and ULD-GGGWRESAI) through the specific protein-peptide interaction. The protein hydrogel was characterized by rheology and scanning electron microscopy (SEM). In vitro cytotoxicity test indicated that the developed protein hydrogel had no apparent cytotoxicity against L-929 cells and HCEC cells after 48h incubation. The formed protein hydrogels was gradually degraded after incubation in phosphate buffered solution (PBS, pH=7.4) for a period of 144h study, as indicated by in vitro degradation test. Encapsulation of model drug (sodium diclofenac; DIC) were achieved by simple mixing of drugs with hydrogelator and the entrapped drugs was almost completely released from hydrogels within 24h via a diffusion manner. As a conclusion, the simple and mild preparation procedure and good biocompatibility of protein hydrogel would render its good promising candidate for drug delivery applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of acute and chronic administration of the GABAB agonist baclofen on 24 hour pH metry and symptoms in control subjects and in patients with gastro-oesophageal reflux disease

PubMed Central

Ciccaglione, A F; Marzio, L

2003-01-01

Background and aims: The γ-aminobutyric acid (GABAB) agonist baclofen has been shown to reduce reflux episodes during the first three postprandial hours in patients with gastro-oesophageal reflux disease (GORD) and in normal controls. The aim of the study was to assess the effect of acute (one day) and chronic (four weeks) administration of baclofen on 24 hour pH metry and symptoms in GORD patients and normal controls. Patients and methods: Acute study: 28 patients with GORD with none or mild oesophagitis at endoscopy and 15 controls underwent oesophageal and gastric 48 hour pH metry in which baclofen or placebo was given for 24 hours in a double blinded manner. Chronic study: 16 GORD patients received baclofen (10 mg four times daily) or placebo for four weeks. Twenty four hour oesophageal pH metry and reflux symptom scores were evaluated before and at the end of treatment. Results: Acute study: the number of reflux episodes and per cent time with pH <4 was significantly lower after baclofen in GORD patients and controls (p<0.003; p<0.0007). Gastric pH increased significantly in GORD patients and controls (p<0.001; p<0.05). Chronic study: four weeks after initial administration of baclofen, the number of reflux episodes and percentage of time with pH <4 significantly decreased in all GORD patients (p<0.003; p<0.02). Symptom scores significantly improved after treatment with baclofen (p<0.0007). Conclusions: The GABAB agonist baclofen reduces 24 hour gastro-oesophageal reflux and increases gastric pH in GORD patients and controls. When given for one month to GORD patients, baclofen reduces oesophageal acid refluxes and significantly improves symptoms. Baclofen may be useful in the therapy of GORD. PMID:12631652

Microbioreactors with microfluidic control and a user-friendly connection to the actuator hardware

NASA Astrophysics Data System (ADS)

Buchenauer, A.; Funke, M.; Büchs, J.; Mokwa, W.; Schnakenberg, U.

2009-07-01

In this study, an array of microbioreactors based on the format of 48-well microtiter plates (MTPs) is presented. The process parameters pH and biomass are monitored online using commercially available optical sensor technology. A microfluidic device dispenses acid or base individually into each well for controlling the pH of fermentations. Fluid volumes from 72 nL to 940 nL can be supplied with valve opening times between 10 ms and 200 ms. One microfluidic device is capable of supplying four wells from two reservoirs. Up to four microfluidic devices can be integrated on the area of a prototype MTP. The devices are fabricated in polydimethylsiloxane (PDMS) using soft lithographic techniques and utilize pneumatically actuated microvalves. During fermentations, the microbioreactor is clamped to an orbital shaker and a temporary pneumatic connection guides the externally controlled pressurized air to the microfluidic device. Finally, fermentations of Escherichia coli in the presence and absence of pH control are carried out in the microbioreactor system over 18 h. During the fermentation the pH of the cultures is continuously monitored by means of optodes. An ammonia solution or phosphoric acid is dispensed to adjust the pH if it differs from the set point of 7.2. In a controlled culture, the pH can be sustained within 7.0 to 7.3 while the pH in an uncontrolled culture ranges between 6.5 and 9.0. This microbioreactor demonstrates the possibility of pH-controlled fermentations in micro-scale. The process control and the user friendly connection to the actuation hardware provide an easy handling comparable to standard MTPs.

A stepwise composite echocardiographic score predicts severe pulmonary hypertension in patients with interstitial lung disease.

PubMed

Bax, Simon; Bredy, Charlene; Kempny, Aleksander; Dimopoulos, Konstantinos; Devaraj, Anand; Walsh, Simon; Jacob, Joseph; Nair, Arjun; Kokosi, Maria; Keir, Gregory; Kouranos, Vasileios; George, Peter M; McCabe, Colm; Wilde, Michael; Wells, Athol; Li, Wei; Wort, Stephen John; Price, Laura C

2018-04-01

European Respiratory Society (ERS) guidelines recommend the assessment of patients with interstitial lung disease (ILD) and severe pulmonary hypertension (PH), as defined by a mean pulmonary artery pressure (mPAP) ≥35 mmHg at right heart catheterisation (RHC). We developed and validated a stepwise echocardiographic score to detect severe PH using the tricuspid regurgitant velocity and right atrial pressure (right ventricular systolic pressure (RVSP)) and additional echocardiographic signs. Consecutive ILD patients with suspected PH underwent RHC between 2005 and 2015. Receiver operating curve analysis tested the ability of components of the score to predict mPAP ≥35 mmHg, and a score devised using a stepwise approach. The score was tested in a contemporaneous validation cohort. The score used "additional PH signs" where RVSP was unavailable, using a bootstrapping technique. Within the derivation cohort (n=210), a score ≥7 predicted severe PH with 89% sensitivity, 71% specificity, positive predictive value 68% and negative predictive value 90%, with similar performance in the validation cohort (n=61) (area under the curve (AUC) 84.8% versus 83.1%, p=0.8). Although RVSP could be estimated in 92% of studies, reducing this to 60% maintained a fair accuracy (AUC 74.4%). This simple stepwise echocardiographic PH score can predict severe PH in patients with ILD.

A stepwise composite echocardiographic score predicts severe pulmonary hypertension in patients with interstitial lung disease

PubMed Central

Bax, Simon; Bredy, Charlene; Kempny, Aleksander; Dimopoulos, Konstantinos; Devaraj, Anand; Walsh, Simon; Jacob, Joseph; Nair, Arjun; Kokosi, Maria; Keir, Gregory; Kouranos, Vasileios; George, Peter M.; McCabe, Colm; Wilde, Michael; Wells, Athol; Li, Wei; Wort, Stephen John; Price, Laura C.

2018-01-01

European Respiratory Society (ERS) guidelines recommend the assessment of patients with interstitial lung disease (ILD) and severe pulmonary hypertension (PH), as defined by a mean pulmonary artery pressure (mPAP) ≥35 mmHg at right heart catheterisation (RHC). We developed and validated a stepwise echocardiographic score to detect severe PH using the tricuspid regurgitant velocity and right atrial pressure (right ventricular systolic pressure (RVSP)) and additional echocardiographic signs. Consecutive ILD patients with suspected PH underwent RHC between 2005 and 2015. Receiver operating curve analysis tested the ability of components of the score to predict mPAP ≥35 mmHg, and a score devised using a stepwise approach. The score was tested in a contemporaneous validation cohort. The score used “additional PH signs” where RVSP was unavailable, using a bootstrapping technique. Within the derivation cohort (n=210), a score ≥7 predicted severe PH with 89% sensitivity, 71% specificity, positive predictive value 68% and negative predictive value 90%, with similar performance in the validation cohort (n=61) (area under the curve (AUC) 84.8% versus 83.1%, p=0.8). Although RVSP could be estimated in 92% of studies, reducing this to 60% maintained a fair accuracy (AUC 74.4%). This simple stepwise echocardiographic PH score can predict severe PH in patients with ILD. PMID:29750141

Use of metallurgical dust for removal chromium ions from aqueous solutions

NASA Astrophysics Data System (ADS)

Pająk, Magdalena; Dzieniszewska, Agnieszka; Kyzioł-Komosińska, Joanna; Chrobok, Michał

2018-01-01

The aim of the study was to determine the potential for the application of dust from steel plant as an effective sorbent for removing Cr(III) and Cr(VI) in the form of simple and complex ions - Acid Blue 193 dye from aqueous solutions. Three isotherms models were used to interpret the experimental results namely: Langmuir, Freundlich, and Dubinin-Radushkevich. Estimated equations parameters allowed to determine the binding mechanism. Based on laboratory studies it was found that the dust was characterized by high sorption capacities for Cr ions and dye from the aqueous solution. The sorption capacity of the dust for Cr(III) and Cr(VI) ions depended on the degree of oxidation, pH of solution and kind of anion and changed in series: Cr(III)-Cl pH=5.0> Cr(III)-SO4 pH=5.0> Cr(III)-Cl pH=3.0> Cr(III)-SO4 pH=3.0> Cr(VI) pH=5.0> Cr(VI) pH=3.0. Dust was also characterized by a high maximum sorption capacity of dye at a range of 38.2 - 91.7 mg/g, depending on the dose of dust. Based on the study it was found that dust from a steel plant, containing iron oxides, can be used as low-cost and effective sorbent to remove pollutions containing chromium ions, especially from acidic wastewater.

Electrochemiluminescent pH sensor measured by the emission potential of TiO2 nanocrystals and its biosensing application.

PubMed

Liu, Xuan; Wang, Nianyue; Zhao, Wei; Jiang, Hui

2015-02-01

This work reports for the first time a potential-based nano-electrochemiluminescent (ECL) pH sensor, using anatase TiO2 nanocrystals (NCs) as the ECL probe. The first ECL peak potential of the TiO2 NCs shifted negatively with increasing pH, showing a linear range from -0.47 V (vs Ag/AgCl) at pH 3 to -1.06 V at pH 10. This phenomenon was attributed to the absorption of 'potential-determining ions' of OH(-) on the surface of TiO2 NCs, leading to larger impedance of the electron injection. Other common 'potential-determining ions', such as phosphate, induced a slight potential shift of 0.03 V at a concentration of 0.1 M. Using urease as an enzyme model, a urea biosensor was developed by the simultaneous modification of urease and TiO2 NCs on indium-tin oxide (ITO) electrodes. The biosensor, measured on the basis of the pH increase caused by the enzyme catalysis reaction, had a linear range of 0.01-2.0 mM, with a potential shift of 0.175 V. The as-prepared pH sensor, which has simple construction procedures and acceptable sensitivity and selectivity, may provide new avenues for the construction of ECL bioanalytical methodologies. Copyright © 2014 John Wiley & Sons, Ltd.

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

Gu, Lina; He, Xiaomei; Wu, Zhenyu, E-mail: zhenyuwuhn@sina.com

Highlights: • Mesoporous Fe{sub 3}O{sub 4}/hydroxyapatite composite was synthesized by a simple, efficient and environmental friendly method. • The prepared material had a large surface area, high pore volume, and good magnetic separability. • DOX-loaded Fe{sub 3}O{sub 4}/hydroxyapatite composite exhibited surprising slow drug release behavior and pH-dependent behavior. - Abstract: In this contribution, we introduced a simple, efficient, and green method of preparing a mesoporous Fe{sub 3}O{sub 4}/hydroxyapatite (HA) composite. The as-prepared material had a large surface area, high pore volume, and good magnetic separability, which made it suitable for targeted drug delivery systems. The chemotherapeutic agent doxorubicin (DOX) wasmore » used to investigate the drug release behavior of Fe{sub 3}O{sub 4}/HA composite. The drug release profiles displayed a little burst effect and pH-dependent behavior. The release rate of DOX at pH 5.8 was larger than that at pH 7.4, which could be attributed to DOX protonation in acid medium. In addition, the released DOX concentrations remained at 0.83 and 1.39 μg/ml at pH 7.4 and 5.8, respectively, which indicated slow, steady, and safe release rates. Therefore, the as-prepared Fe{sub 3}O{sub 4}/hydroxyapatite composite could be an efficient platform for targeted anticancer drug delivery.« less

Resin characterization

Treesearch

Robert L. Geimer; Robert A. Follensbee; Alfred W. Christiansen; James A. Koutsky; George E. Myers

1990-01-01

Currently, thermosetting adhesives are characterized by physical andchemical features such as viscosity, solids content, pH, and molecular distribution, and their reaction in simple gel tests. Synthesis of a new resin for a particular application is usually accompanied by a series of empirical laboratory and plant trials. The purpose of the research outlined in this...

Using the Creative Cognition Approach in Essay Assignments in Leadership Education

ERIC Educational Resources Information Center

Atkinson, Tim

2018-01-01

This application brief covers, "The Final Question," an alternative essay design that encourages the learner to think creatively in Ph.D. Organization Theory or Leadership courses. "The Final Question" asks, "Do leaders change organizations or do organizations change leaders?" It is a simple question, but only the…

Autonomously Self-Adhesive Hydrogels as Building Blocks for Additive Manufacturing.

PubMed

Deng, Xudong; Attalla, Rana; Sadowski, Lukas P; Chen, Mengsu; Majcher, Michael J; Urosev, Ivan; Yin, Da-Chuan; Selvaganapathy, P Ravi; Filipe, Carlos D M; Hoare, Todd

2018-01-08

We report a simple method of preparing autonomous and rapid self-adhesive hydrogels and their use as building blocks for additive manufacturing of functional tissue scaffolds. Dynamic cross-linking between 2-aminophenylboronic acid-functionalized hyaluronic acid and poly(vinyl alcohol) yields hydrogels that recover their mechanical integrity within 1 min after cutting or shear under both neutral and acidic pH conditions. Incorporation of this hydrogel in an interpenetrating calcium-alginate network results in an interfacially stiffer but still rapidly self-adhesive hydrogel that can be assembled into hollow perfusion channels by simple contact additive manufacturing within minutes. Such channels withstand fluid perfusion while retaining their dimensions and support endothelial cell growth and proliferation, providing a simple and modular route to produce customized cell scaffolds.

The Urinary Uric Acid/Creatinine Ratio is An Adjuvant Marker for Perinatal Asphyxia

PubMed Central

Bhongir, Aparna Varma; Yakama, Akhil Varma Venkata; Saha, Subhajit; Radia, Sejal B.; Pabbati, Jayalakshmi

2015-01-01

Objective To assess the urinary uric acid/creatinine ratio (UA/Cr) in relation to Apgar score and cord blood gas analysis in identification of perinatal asphyxia and to define the cutoff values. Design case control study. Setting The newborns admitted in the department of pediatrics and NICU of Mediciti Institute of Medical Science, Ghanpur, Medchal mandal, Telangana from May-July 2011 were enrolled. Participants/patients The study was conducted on 31 (18 males, 13 females) controls and 18 (12males, 6 females) asphyxiated neonates. Outcome Measure(s) 5ml of arterial cord blood of newborn collected at the time of birth and spot urine samples were collected within 24-72 hours of life. Cord blood gas analysis were done immediately and Urinary uric acid was measured by modified Uricase method, urinary creatinine by modified kinetic Jaffe's reaction. Results The mean urinary uric acid and creatinine ratio (2.58± 0.48 vs 1.89 ± 0.59) is significantly higher in Asphyxiated group than in the control group. The umbilical cord blood pH had significant positive correlation with 1st minute Apgar score (r= 0.41, p=0.003), 5th minute Apgar (r= 0.44, p=0.002), while urinary UA/Cr ratio had significant negative correlation with cord blood pH (r= -0.63, p=0.002). Urinary UA/Cr ratio with criterion of >2.43 had 80% sensitivity, 87.5% specificity with AUC of 0.84 (p=0.003) had a better predictive value. Conclusions Urinary UA/Cr ratio is easy, non-invasive, painless and economical adjuvant parameter with better predictive value for diagnosing perinatal asphyxia with simple diagnostic equipment. PMID:26998526

Gastrointestinal manifestations of cow's milk allergy.

PubMed

Magazzù, Giuseppe; Scoglio, Riccardo

2002-12-01

To review and discuss the relationship between cow's milk allergy (CMA) and some gastrointestinal manifestations, such as gastroesophageal reflux, constipation, food protein-induced enterocolitis, and food-induced eosinophilic proctocolitis, with respect to diagnostic strategies that might eliminate the need for a double-blind, placebo-controlled oral food challenge (DBPCFC). A review of pertinent PubMed articles, published during the past 10 years, was performed. To obtain positive and negative predictive values known as posterior probabilities and to calculate the likelihood ratio, only those studies including both patients and control subjects were selected for analysis. With respect to gastroesophageal reflux, a typical 24-hour esophageal pH monitoring pattern might obviate the performance of a DBPCFC in patients with symptoms of reflux suspected of having CMA, provided this pH pattern is confirmed in other studies. A relationship between CMA and constipation has been reported in only one prospective controlled study; the clinical and laboratory variables of perianal lesions, histologic abnormalities, and signs of hypersensitivity had likelihood ratios of 2.2, 2.4, and 3.7, respectively, and posttest probabilities of 83, 84, and 88%, respectively. Therefore, a DBPCFC is warranted. In reference to food protein-induced enterocolitis, clinical and laboratory criteria suggested in the literature for defining a food challenge as positive have not been prospectively evaluated in the untreated state. Some simple stool tests, such as fecal tumor necrosis factor-alpha and alpha1-antitrypsin determination, might be candidates for diagnostic studies in patients with food protein-induced enterocolitis, if prospectively evaluated. In infants with food-induced eosinophilic proctocolitis, rectal biopsy invariably shows eosinophilic infiltration and thus makes performance of a DBPCFC unnecessary. Although the current diagnosis of gastrointestinal manifestations of CMA usually depends on a DBPCFC, investigators continue to study other options for confirming the diagnosis.

Human polyhomeotic homolog 3 (PHC3) sterile alpha motif (SAM) linker allows open-ended polymerization of PHC3 SAM.

PubMed

Robinson, Angela K; Leal, Belinda Z; Nanyes, David R; Kaur, Yogeet; Ilangovan, Udayar; Schirf, Virgil; Hinck, Andrew P; Demeler, Borries; Kim, Chongwoo A

2012-07-10

Sterile alpha motifs (SAMs) are frequently found in eukaryotic genomes. An intriguing property of many SAMs is their ability to self-associate, forming an open-ended polymer structure whose formation has been shown to be essential for the function of the protein. What remains largely unresolved is how polymerization is controlled. Previously, we had determined that the stretch of unstructured residues N-terminal to the SAM of a Drosophila protein called polyhomeotic (Ph), a member of the polycomb group (PcG) of gene silencers, plays a key role in controlling Ph SAM polymerization. Ph SAM with its native linker created shorter polymers compared to Ph SAM attached to either a random linker or no linker. Here, we show that the SAM linker for the human Ph ortholog, polyhomeotic homolog 3 (PHC3), also controls PHC3 SAM polymerization but does so in the opposite fashion. PHC3 SAM with its native linker allows longer polymers to form compared to when attached to a random linker. Attaching the PHC3 SAM linker to Ph SAM also resulted in extending Ph SAM polymerization. Moreover, in the context of full-length Ph protein, replacing the SAM linker with PHC3 SAM linker, intended to create longer polymers, resulted in greater repressive ability for the chimera compared to wild-type Ph. These findings show that polymeric SAM linkers evolved to modulate a wide dynamic range of SAM polymerization abilities and suggest that rationally manipulating the function of SAM containing proteins through controlling their SAM polymerization may be possible.

Automatic pH Control and Soluble and Insoluble Substrate Input for Continuous Culture of Rumen Microorganisms

PubMed Central

Slyter, Leonard L.

1975-01-01

An artifical rumen continuous culture with pH control, automated input of water-soluble and water-insoluble substrates, controlled mixing of contents, and a collection system for gas is described. Images PMID:16350029

Single-molecule spectroscopy of the unexpected collapse of an unfolded protein at low pH

NASA Astrophysics Data System (ADS)

Hofmann, Hagen; Nettels, Daniel; Schuler, Benjamin

2013-09-01

The dimensions of intrinsically disordered and unfolded proteins critically depend on the solution conditions, such as temperature, pH, ionic strength, and osmolyte or denarurant concentration. However, a quantitative understanding of how the complex combination of chain-chain and chain-solvent interactions is affected by the solvent is still missing. Here, we take a step towards this goal by investigating the combined effect of pH and denaturants on the dimensions of an unfolded protein. We use single-molecule fluorescence spectroscopy to extract the dimensions of unfolded cold shock protein (CspTm) in mixtures of the denaturants urea and guanidinium chloride (GdmCl) at neutral and acidic pH. Surprisingly, even though a change in pH from 7 to 2.9 increases the net charge of CspTm from -3.8 to +10.2, the radius of gyration of the chain is very similar under both conditions, indicating that protonation of acidic side chains at low pH results in additional hydrophobic interactions. We use a simple shared binding site model that describes the joint effect of urea and GdmCl, together with polyampholyte theory and an ion cloud model that includes the chemical free energy of counterion interactions and side chain protonation, to quantify this effect.

Systematic generation of buffer systems for pH gradient ion exchange chromatography and their application.

PubMed

Kröner, Frieder; Hubbuch, Jürgen

2013-04-12

pH gradient protein separations are widely used techniques in the field of protein analytics, of which isoelectric focusing is the most well known application. The chromatographic variant, based on the formation of pH gradients in ion exchange columns is only rarely applied due to the difficulties to form controllable, linear pH gradients over a broad pH range. This work describes a method for the systematic generation of buffer compositions with linear titration curves, resulting in well controllable pH gradients. To generate buffer compositions with linear titration curves an in silico method was successfully developed. With this tool, buffer compositions for pH gradient ion exchange chromatography with pH ranges spanning up to 7.5 pH units were established and successfully validated. Subsequently, the buffer systems were used to characterize the elution behavior of 22 different model proteins in cation and anion exchange pH gradient chromatography. The results of both chromatographic modes as well as isoelectric focusing were compared to describe differences in between the methods. Copyright © 2013 Elsevier B.V. All rights reserved.

Asthma control using fluticasone propionate/salmeterol in Asian and non-Asian populations: a post hoc analysis of the GOAL study.

PubMed

Bousquet, Jean; Barnes, Neil; Gibbs, Michael; Gul, Nadeem; Tomkins, Susan A; Zhou, Xin; Cho, Young-Joo; Park, Hae-Sim; Busse, William; Zhong, Nanshan

2017-04-28

To analyse the efficacy of fluticasone propionate (FP) alone and combined with salmeterol (SAL) in achieving guideline-defined asthma control in Asian patients. A post hoc analysis of the GOAL study in which patients were stratified by prior-medication use into inhaled corticosteroid (ICS)-naïve (Stratum [S] 1), low-dose ICS (S2), and medium-dose ICS (S3), and randomised to receive FP/SAL or FP. Doses were stepped-up every 12 weeks until Totally Controlled asthma or maximum dose was reached (PhI) and then maintained until study end (PhII). The primary endpoint was the proportion of patients achieving Well-Controlled asthma during PhI. Additional endpoints included Total Control and adverse events. Asian and non-Asian patients were analysed separately. In Asian patients in PhI, 74% (n = 87/118) in S1 achieved Well-Controlled asthma with FP/SAL versus 74% (n = 89/121) with FP alone (p = 0.839); corresponding values were 76% (n = 81/107) versus 60% (n = 62/104; p = 0.005) in S2, and 58% (n = 59/102) versus 43% (n = 41/95; p = 0.015) in S3. More patients in all three strata achieved Totally Controlled asthma with FP/SAL versus FP alone. Control was achieved more rapidly and with lower ICS doses with FP/SAL versus FP. A high proportion of patients who achieved control during PhI maintained control during PhII. Similar trends were found in non-Asian patients. No new safety concerns were identified. A greater proportion of Asian patients (S2 and S3, for Well-Controlled; all strata, for Totally Controlled) achieved guideline-defined asthma control with FP/SAL versus FP alone. High proportions of Asian patients in S1 achieved Well-Controlled asthma in both treatment groups.

Effects of soap and detergents on skin surface pH, stratum corneum hydration and fat content in infants.

PubMed

Gfatter, R; Hackl, P; Braun, F

1997-01-01

In adults the influence of cleansing preparations on the pH, fat content and hydration of the skin is well documented. Studies in newborn and small infants have not been reported. Our study aimed at examining whether similar effects can be ascertained in infants. Infants without skin disease, aged 2 weeks to 16 months, entered an open, controlled and randomized study. Ten infants each had skin washed with tap water (control group), liquid detergent (pH 5.5), compact detergent (pH 5.5) or alkaline soap (pH 9.5). The pH, fat content and hydration were measured before and 10 min after cleansing. Findings were statistically evaluated by parametric covariance analysis. The skin pH increased from an average of 6.60 after cleansing in all groups. The smallest increase (+0.19) was observed in the control group, the largest (+0.45) after washing with alkaline soap. After treatment with liquid or compact detergent, the increase of the pH was only 0.09 higher than for the control group. In comparison to the compact and liquid detergents, the alkaline soap group had a significantly higher increase in pH. The fat content (mean starting value: 4.34 micrograms/cm2) decreased after washing in all groups; the smallest effect was observed in the control group (decrease of 0.93 micrograms/cm2), the highest for the alkaline soap group (decrease of 4.81 micrograms/cm2). In comparison to the compact and liquid detergents, the alkaline soap group had a higher decrease in fat content. This difference was significant for compact detergents. No statistically significant differences were observed for hydration before versus after washing. Each cleansing agent, even normal tap water, influences the skin surface. The increase of the skin pH irritates the physiological protective 'acid mantle', changes the composition of the cutaneous bacterial flora and the activity of enzymes in the upper epidermis, which have an acid pH optimum. The dissolution of fat from the skin surface may influence the hydration status leading to a dry and squamous skin.

Potentiometric chip-based multipumping flow system for the simultaneous determination of fluoride, chloride, pH, and redox potential in water samples.

PubMed

Chango, Gabriela; Palacio, Edwin; Cerdà, Víctor

2018-08-15

A simple potentiometric chip-based multipumping flow system (MPFS) has been developed for the simultaneous determination of fluoride, chloride, pH, and redox potential in water samples. The proposed system was developed by using a poly(methyl methacrylate) chip microfluidic-conductor using the advantages of flow techniques with potentiometric detection. For this purpose, an automatic system has been designed and built by optimizing the variables involved in the process, such as: pH, ionic strength, stirring and sample volume. This system was applied successfully to water samples getting a versatile system with an analysis frequency of 12 samples per hour. Good correlation between chloride and fluoride concentration measured with ISE and ionic chromatography technique suggests satisfactory reliability of the system. Copyright © 2018 Elsevier B.V. All rights reserved.

[Significance of pharyngeal biochemical indexes in the diagnosis of laryngopharyngeal reflux disease].

PubMed

Wang, L; Wu, W; Wang, G

2018-02-27

Objective: To investigate the significance of the detection of pepsin in saliva and the pharyngeal pH monitoring in the diagnosis of laryngopharyngeal reflux disease(LPRD). Methods: A total of 176 patients (140 patients with simple pharyngitis and 36 patients with space-occupying lesions of larynx) who were suspected to have laryngopharyngeal reflux between February and December 2016 were retrospectively reviewed. All the patients were evaluated with reflux symptom index (RSI), reflux finding score (RFS) and 24-hour pharyngeal pH monitoring(Dx-pH). Saliva of patients was collected and the pepsin in the saliva was measured by enzyme-linked immunosorbent assay (ELISA). Results: The positive rate of RSI (RSI>13) and/or RFS (RFS>7) was 56.8% (100/176). The positive rate of pepsin in saliva was 40.9% (72/176) and pepsin in saliva collected at the time of onset of symptom was much higher than that at other time points ( P <0.001). The positive rate of pepsin in saliva, Ryan score and the pH<6.0 laryngopharyngeal reflux in space-occupying lesions group [55.6%(20/36), 27.8% (10/36), 69.4%(25/36), respectively] were all higher than simple pharyngitis group [37.1% (52/140), 5.0% (7/140), 50% (70/140), respectively] ( P =0.045, P <0.001, P =0.037, respectively). Conclusions: The detection of pepsin in saliva and the pharyngeal pH monitoring reflected different reflux agents, and there was great significance for the diagnosis of LPRD by using two methods together. We found that the weak acid state and consequent pepsin damage played an important role in the occurrence and development of space-occupying lesions of larynx.

Processes controlling dissolved oxygen and pH in the upper Willamette River basin, Oregon, 1994

USGS Publications Warehouse

Pogue, Ted R.; Anderson, Chauncey W.

1995-01-01

In July and August of 1994, the U. S. Geological Survey in cooperation with the Oregon Department of Environmental Quality (ODEQ) collected data to document the spatial extent and diel variability of dissolved oxygen (DO) concentrations and pH levels in selected reaches of streams in the upper Willamette River Basin. These data were also collected to identify primary factors that control DO concentrations downstream from major point sources as well as to provide ODEQ with data to refine calibration of their steady-state DO and nutrient models for the upper Willamette River Basin. All of the reaches studied had diel variations in DO and pH. The magnitude of the diel variations in DO ranged from 0.2 to 3.9 milligrams per liter (7 to 50 percent-saturation units based on ambient water temperature and barometric pressure) and in pH from 0.3 to 1.4 units. However, of the reaches studied, only the Coast Fork Willamette River from river mile (RM) 21.7 to 12.5 and the Willamette River from RM 151 to 141.6 had field measured violations of State standards for DO and pH. DO concentration and pH in water depend on many factors. Data were collected to examine several major factors, including BOD (biochemical oxygen demand), carbonaceous BOD, nitrogenous BOD, and measures of photosynthetic activity. Of the four study reaches, only a short stretch of the Coast Fork Willamette River has potential for important levels of oxygen consumption from BOD or nitrification. Additionally, water-column primary-productivity measurements indicated that respiration and photosynthesis by free-floating algae did not explain the observed diel variations in DO in the study reaches. Results from a simple mathematical model incorporating measures of community respiration and net primary productivities indicated that periphyton are capable of producing a diel variation of the order of magnitude observed during the August study period. In the Willamette River near Peoria, the combined periphyton DO consumption and production estimate at RM 151 (2.4 mg/L) and RM 144.6 (1.7 mg/L) would account for 90 and 63 percent, respectively, of the observed diel fluctuation. The estimates for the Corvallis reach at RM 132.6 (0.4 mg/L) and RM 130.7 (2.9 mg/L) had a considerably larger range of 36 to 264 percent of DO saturation, respectively. Therefore, because BOD and phytoplankton do not appear to be important contributors to diel DO fluctuations, periphyton are likely the primary contributor to diel fluctuations in the upper Willamette River Basin during July and August.

Migration of the guinea pig sperm membrane protein PH-20 from one localized surface domain to another does not occur by a simple diffusion-trapping mechanism.

PubMed

Cowan, A E; Myles, D G; Koppel, D E

1991-03-01

The redistribution of membrane proteins on the surface of cells is a prevalent feature of differentiation in a variety of cells. In most cases the mechanism responsible for such redistribution is poorly understood. Two potential mechanisms for the redistribution of surface proteins are: (1) passive diffusion coupled with trapping, and (2) active translocation. We have studied the process of membrane protein redistribution for the PH-20 protein of guinea pig sperm, a surface protein required for sperm binding to the egg zona pellucida (P. Primakoff, H. Hyatt, and D. G. Myles (1985). J. Cell Biol. 101, 2239-2244). PH-20 protein is localized to the posterior head plasma menbrane of the mature sperm cell. Following the exocytotic acrosome reaction, PH-20 protein moves into the newly incorporated inner acrosomal membrane (IAM), placing it in a position favorable for a role in binding sperm to the egg zona pellucida (D. G. Myles, and P. Primakoff (1984), J. Cell Biol. 99, 1634-1641). To analyze the mechanistic basis for this protein migration, we have used fluorescence microscopy and digital image processing to characterize PH-20 protein migration in individual cells. PH-20 protein was observed to move against a concentration gradient in the posterior head plasma membrane. This result argues strongly against a model of passive diffusion followed by trapping in the IAM, and instead suggests that an active process serves to concentrate PH-20 protein toward the boundary separating the posterior head and IAM regions. A transient gradient of PH-20 concentration observed in the IAM suggests that once PH-20 protein reaches the IAM, it is freely diffusing. Additionally, we observed that migration of PH-20 protein was calcium dependent.

Influence of pH, particle size and crystal form on dissolution behaviour of engineered nanomaterials.

PubMed

Avramescu, M-L; Rasmussen, P E; Chénier, M; Gardner, H D

2017-01-01

Solubility is a critical component of physicochemical characterisation of engineered nanomaterials (ENMs) and an important parameter in their risk assessments. Standard testing methodologies are needed to estimate the dissolution behaviour and biodurability (half-life) of ENMs in biological fluids. The effect of pH, particle size and crystal form on dissolution behaviour of zinc metal, ZnO and TiO 2 was investigated using a simple 2 h solubility assay at body temperature (37 °C) and two pH conditions (1.5 and 7) to approximately frame the pH range found in human body fluids. Time series dissolution experiments were then conducted to determine rate constants and half-lives. Dissolution characteristics of investigated ENMs were compared with those of their bulk analogues for both pH conditions. Two crystal forms of TiO 2 were considered: anatase and rutile. For all compounds studied, and at both pH conditions, the short solubility assays and the time series experiments consistently showed that biodurability of the bulk analogues was equal to or greater than biodurability of the corresponding nanomaterials. The results showed that particle size and crystal form of inorganic ENMs were important properties that influenced dissolution behaviour and biodurability. All ENMs and bulk analogues displayed significantly higher solubility at low pH than at neutral pH. In the context of classification and read-across approaches, the pH of the dissolution medium was the key parameter. The main implication is that pH and temperature should be specified in solubility testing when evaluating ENM dissolution in human body fluids, even for preliminary (tier 1) screening.

Analysis of the genetic basis of plant height-related traits in response to ethylene by QTL mapping in maize (Zea mays L.).

PubMed

Zhang, Weiqiang; Li, Zhi; Fang, Hui; Zhang, Mingcai; Duan, Liusheng

2018-01-01

Ethylene (ET) is critical importance in the growth, development, and stress responses of plants. Plant hormonal stress responses have been extensively studied, however, the role of ET in plant growth, especially plant height (PH) remains unclear. Understanding the genetic control for PH in response to ET will provide insights into the regulation of maize development. To clarify the genetic basis of PH-related traits of maize in response to ET, we mapped QTLs for PH, ear height (EH), and internode length above the uppermost ear (ILAU) in two recombinant inbred line (RIL) populations of Zea mays after ET treatment and in an untreated control (CK) group. Sixty QTLs for the three traits were identified. Twenty-two QTLs were simultaneously detected under both ET treatment and untreated control, and five QTLs were detected at two geographic locations under ET treatment only. Individual QTL can be explained 3.87-17.71% of the phenotypic variance. One QTL (q2PH9-1, q1PH9, q1EH9/q1ILAU9-1, q2ILAU9, and q2EH9) for the measured traits (PH, EH, ILAU) was consistent across both populations. Two QTLs (q2PH2-5, q2ILAU2-2, q1PH2-2, and q1ILAU2-2; q1PH8-1, q1EH8-1, q2PH8-1) were identified for up to two traits in both locations and populations under both ET treatment and untreated control. These consistent and stable regions are important QTLs of potential hot spots for PH, ear height (EH), and internode length above the uppermost ear (ILAU) response to ET in maize; therefore, QTL fine-mapping and putative candidate genes validation should enable the cloning of PH, EH, and ILAU related genes to ET response. These results will be valuable for further fine-mapping and quantitative trait nucleotides (QTNs) determination, and elucidate the underlying molecular mechanisms of ET responses in maize.

Analysis of the genetic basis of plant height-related traits in response to ethylene by QTL mapping in maize (Zea mays L.)

PubMed Central

Li, Zhi; Fang, Hui; Zhang, Mingcai; Duan, Liusheng

2018-01-01

Ethylene (ET) is critical importance in the growth, development, and stress responses of plants. Plant hormonal stress responses have been extensively studied, however, the role of ET in plant growth, especially plant height (PH) remains unclear. Understanding the genetic control for PH in response to ET will provide insights into the regulation of maize development. To clarify the genetic basis of PH-related traits of maize in response to ET, we mapped QTLs for PH, ear height (EH), and internode length above the uppermost ear (ILAU) in two recombinant inbred line (RIL) populations of Zea mays after ET treatment and in an untreated control (CK) group. Sixty QTLs for the three traits were identified. Twenty-two QTLs were simultaneously detected under both ET treatment and untreated control, and five QTLs were detected at two geographic locations under ET treatment only. Individual QTL can be explained 3.87–17.71% of the phenotypic variance. One QTL (q2PH9-1, q1PH9, q1EH9/q1ILAU9-1, q2ILAU9, and q2EH9) for the measured traits (PH, EH, ILAU) was consistent across both populations. Two QTLs (q2PH2-5, q2ILAU2-2, q1PH2-2, and q1ILAU2-2; q1PH8-1, q1EH8-1, q2PH8-1) were identified for up to two traits in both locations and populations under both ET treatment and untreated control. These consistent and stable regions are important QTLs of potential hot spots for PH, ear height (EH), and internode length above the uppermost ear (ILAU) response to ET in maize; therefore, QTL fine-mapping and putative candidate genes validation should enable the cloning of PH, EH, and ILAU related genes to ET response. These results will be valuable for further fine-mapping and quantitative trait nucleotides (QTNs) determination, and elucidate the underlying molecular mechanisms of ET responses in maize. PMID:29466465

Parent weight change predicts child weight change in family-based weight control program for pre-school children (Buffalo healthy tots)

USDA-ARS?s Scientific Manuscript database

Title: PARENT WEIGHT CHANGE PREDICTS CHILD WEIGHT CHANGE IN FAMILY-BASED WEIGHT CONTROL PROGRAM FOR PRE-SCHOOL CHILDREN (BUFFALO HEALTHY TOTS), Teresa Quattrin, MOl, James N Roemmich, PhDI, Rocco Paluch, MAl, Jihnhee Yu, PhD2, Leonard H Epstein, PhDI and Michelle A Ecker, RD, CDEI . lpediatrics, Uni...

Complete nutrient recovery from source-separated urine by nitrification and distillation.

PubMed

Udert, K M; Wächter, M

2012-02-01

In this study we present a method to recover all nutrients from source-separated urine in a dry solid by combining biological nitrification with distillation. In a first process step, a membrane-aerated biofilm reactor was operated stably for more than 12 months, producing a nutrient solution with a pH between 6.2 and 7.0 (depending on the pH set-point), and an ammonium to nitrate ratio between 0.87 and 1.15 gN gN(-1). The maximum nitrification rate was 1.8 ± 0.3 gN m(-2) d(-1). Process stability was achieved by controlling the pH via the influent. In the second process step, real nitrified urine and synthetic solutions were concentrated in lab-scale distillation reactors. All nutrients were recovered in a dry powder except for some ammonia (less than 3% of total nitrogen). We estimate that the primary energy demand for a simple nitrification/distillation process is four to five times higher than removing nitrogen and phosphorus in a conventional wastewater treatment plant and producing the equivalent amount of phosphorus and nitrogen fertilizers. However, the primary energy demand can be reduced to values very close to conventional treatment, if 80% of the water is removed with reverse osmosis and distillation is operated with vapor compression. The ammonium nitrate content of the solid residue is below the limit at which stringent EU safety regulations for fertilizers come into effect; nevertheless, we propose some additional process steps that will increase the thermal stability of the solid product. Copyright © 2011 Elsevier Ltd. All rights reserved.

A simple reactive-transport model of calcite precipitation in soils and other porous media

NASA Astrophysics Data System (ADS)

Kirk, G. J. D.; Versteegen, A.; Ritz, K.; Milodowski, A. E.

2015-09-01

Calcite formation in soils and other porous media generally occurs around a localised source of reactants, such as a plant root or soil macro-pore, and the rate depends on the transport of reactants to and from the precipitation zone as well as the kinetics of the precipitation reaction itself. However most studies are made in well mixed systems, in which such transport limitations are largely removed. We developed a mathematical model of calcite precipitation near a source of base in soil, allowing for transport limitations and precipitation kinetics. We tested the model against experimentally-determined rates of calcite precipitation and reactant concentration-distance profiles in columns of soil in contact with a layer of HCO3--saturated exchange resin. The model parameter values were determined independently. The agreement between observed and predicted results was satisfactory given experimental limitations, indicating that the model correctly describes the important processes. A sensitivity analysis showed that all model parameters are important, indicating a simpler treatment would be inadequate. The sensitivity analysis showed that the amount of calcite precipitated and the spread of the precipitation zone were sensitive to parameters controlling rates of reactant transport (soil moisture content, salt content, pH, pH buffer power and CO2 pressure), as well as to the precipitation rate constant. We illustrate practical applications of the model with two examples: pH changes and CaCO3 precipitation in the soil around a plant root, and around a soil macro-pore containing a source of base such as urea.

The effect of pH control and 'hydraulic flush' on hydrolysis and Volatile Fatty Acids (VFA) production and profile in anaerobic leach bed reactors digesting a high solids content substrate.

PubMed

Cysneiros, Denise; Banks, Charles J; Heaven, Sonia; Karatzas, Kimon-Andreas G

2012-11-01

The effect of hydraulic flush and pH control on hydrolysis, Volatile Fatty Acids (VFA) production and profile in anaerobic leach bed reactors was investigated for the first time. Six reactors were operated under different regimes for two consecutive batches of 28days each. Buffering at pH ∼6.5 improved hydrolysis (Volatile Solid (VS) degradation) and VFA production by ∼50%. Butyric and acetic acid were dominant when reactors were buffered, while only butyric acid was produced at low pH. Hydraulic flush enhanced VS degradation and VFA production by ∼15% and ∼32%, respectively. Most Probable Number (MPN) of cellulolytic microorganisms indicated a wash out when hydraulic flush was applied, but pH control helped to counteract this. The highest VS degradation (∼89%), VFA yield (0.84kgCODkg(-1)VS(added)) and theoretical methane potential (0.37m(3)CH(4)kg(-1)VS(added)) were obtained when pH control and hydraulic flush were applied, and therefore, these conditions are recommended. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of pH on the quantum-size-controlled photoelectrochemical etching of epitaxial InGaN quantum dots

DOE PAGES

Xiao, Xiaoyin; Lu, Ping; Fischer, Arthur J.; ...

2015-11-18

Illumination by a narrow-band laser has been shown to enable photoelectrochemical (PEC) etching of InGaN thin films into quantum dots with sizes controlled by the laser wavelength. Here, we investigate and elucidate the influence of solution pH on such quantum-size-controlled PEC etch process. We find that although a pH above 5 is often used for PEC etching of GaN-based materials, oxides (In 2O 3 and/or Ga 2O 3) form which interfere with quantum dot formation. Furthermore, at pH below 3, however, oxide-free QDs with self-terminated sizes can be successfully realized.

Habit-associated salivary pH changes in oral submucous fibrosis-A controlled cross-sectional study.

PubMed

Donoghue, Mandana; Basandi, Praveen S; Adarsh, H; Madhushankari, G S; Selvamani, M; Nayak, Prachi

2015-01-01

Oral submucous fibrosis (OSF) is a multi-causal inflammatory reaction to the chemical or mechanical trauma caused due to exposure to arecanut containing products with or without tobacco (ANCP/T). Arecanut and additional components such as lime and chewing tobacco render ANCP/T highly alkaline. Fibrosing repair is a common reaction to an alkaline exposure in the skin. OSF may be related to the alkaline exposure by ANCP/T in a similar manner. The study was aimed at establishing the relationship of habit-associated salivary pH changes and OSF. The study design was controlled cross-sectional. Base line salivary pH (BLS pH), salivary pH after chewing the habitual ANCP/T substance, post chew salivary pH (PCSpH) for 2 min and salivary pH recovery time (SpHRT) were compared in 30 OSF patients and 30 sex-matched individuals with ANCP/T habits and apparently healthy oral mucosa. The group's mean BLSpH values were similar and within normal range and representative of the population level values. The average PCSpH was significantly higher (P ˂ 0.0001) than the average BLSpH in both groups. There was no significant difference (P = 0.09) between PCSpH of OSF patients and controls. OSF patients had a significantly longer (P = 0.0076) SpHRT than controls. Factors such as age, daily exposure, cumulative habit years, BLSpH and PCSpH, had varying effects on the groups. Chewing ANCP/T causes a significant rise in salivary pH of all individuals. SpHRT has a significant association with OSF. The effect of salivary changes in OSF patients differs with those in healthy controls.

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

NONE

Many times the start up of granular activated carbon adsorption systems for the control of organic contaminants in wastewater cm exhibit unacceptable increases in the adscurber effluent pH. Experience shows that the duration of the pH increase ranges from several hours to several days, during which time several hundred bed volumes of water can be discharged with a pH in excess of 9. Laboratory studies have identified the cause of the pH rise as an interaction between the naturally occurring anions and protons ar the water and the carbon surface. The interaction can be described as an ion exchange typemore » of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. Capacities of the carbon for the anions range from 2 to 9 mg/g GAC, depending upon the water characteristics, the carbon type, the nature of the anion and its influent concentration. These studies have shown de the anion sorption and resulting pH increase is independent of the raw material used for die activated carbon production, e.g. bituminous or sub-bituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface rather than the water chemistry. The change to the carbon surface is accomplished through a controlled oxidation process. This process provides a more acidic carbon surface with a reduced affinity for the anions in the waste water. As a result, the pH excursions above 9 are eliminated and the initial effluent from the adsorption system can be discharged without further treatment.« less

Effects of environmental pH and calcium on ammonia toxicity in channel catfish

USGS Publications Warehouse

Tomasso, J.R.; Goudie, C.A.; Simco, B.A.; Davis, K.B.

1980-01-01

The twenty-four-hour median lethal concentrations (24-hour LC50) of total ammonia nitrogen (TA-N) to channel catfish (Ictalurus punctatus) at pH 7, 8, and 9 (total hardness, 40 mg/liter; temperature, 21–25 C) were 263.6 ± 11.3 (SE), 38.8 ± 1.8, and 4.5 ± 0.2 mg/liter, respectively. The 24-hour LC50 of un-ionized ammonia nitrogen (UIA-N) concentration at pH 8 was significantly higher (1.82 ± 0.06 mg/liter) than at pH 7 or 9 (1.39 ± 0.06 and 1.49 ± 0.12 mg/liter). Enrichment of the water to 440 mg/liter total hardness at pH 7 significantly increased the 24-hour LC50 of TA-N and UIA-N (356.3 ± 16.4 and 1.79 ± 0.07). Fish exposed to 25 mg/liter TA-N for 12 hours at pH 7 and 8 showed no differences from control fish in hematocrit, percent total plasma protein, or plasma and muscle chloride. Plasma sodium showed no difference between control and experimental groups at pH 7; however, a significant decrease occurred in fish exposed to 25 mg/liter TA-N at pH 8. No differences in blood pH were found between the control groups and fish exposed to 100 and 200 mg/liter TA-N at pH 7, and to 10 and 25 mg/liter TA-N at pH 8. Plasma sodium depletion is suggested as a contributing mechanism of ammonia toxicity.

Influence of solution chemistry on the boron content in inorganic calcite grown in artificial seawater

NASA Astrophysics Data System (ADS)

Uchikawa, Joji; Harper, Dustin T.; Penman, Donald E.; Zachos, James C.; Zeebe, Richard E.

2017-12-01

The ratio of boron to calcium (B/Ca) in marine biogenic carbonates has been proposed as a proxy for properties of seawater carbonate chemistry. Applying this proxy to planktic foraminifera residing in the surface seawater largely in equilibrium with the atmosphere may provide a valuable handle on past atmospheric CO2 concentrations. However, precise controls on B/Ca in planktic foraminifera remain enigmatic because it has been shown to depend on multiple physicochemical seawater properties. To help establish a firm inorganic basis for interpreting the B/Ca records, we examined the effect of a suite of chemical parameters ([Ca2+], pH, [DIC], salinity and [PO43-]) on B/Ca in inorganic calcite precipitated in artificial seawater. These parameters were primarily varied individually while keeping all others constant, but we also tested the influence of pH and [DIC] at a constant calcite precipitation rate (R) by concurrent [Ca2+] adjustments. In the simple [Ca2+], pH and [DIC] experiments, both R and B/Ca increased with these parameters. In the pH-[Ca2+] and [DIC]-[Ca2+] experiments at constant R, on the other hand, B/Ca was invariant at different pH and decreased with [DIC], respectively. These patterns agree with the behavior of solution [BTotal/DIC] ratio such that, at a fixed [BTotal], it is independent of pH but decreases with [DIC]. Based on these results, R and [BTotal/DIC] ratio appear to be the primary controls on B/Ca in inorganic calcite, suggesting that both B(OH)4- and B(OH)3 are possibly involved in B incorporation. Moreover, B/Ca modestly increased with salinity and [PO43-]. Inorganic calcite precipitated at higher R and in the presence of oxyanions such as SO42- and PO43- in growth solutions often undergoes surface roughening due to formation of crystallographic defects, vacancies and, occasionally, amorphous/hydrous CaCO3. These non-lattice sites may provide additional space for B, particularly B(OH)3. Consequently, besides the macroscopic influence of R and bulk solution chemistry, molecular-scale processes associated with calcite nucleation can be an important consideration for B incorporation, especially in complex ionic solutions. Lastly, the covariance of B/Ca with [DIC] and salinity observed here qualitatively agrees with those in planktic foraminifers. It follows that their impact on foraminiferal B/Ca is partly inorganically driven, which may explain why the effect is evident across different species.

Two-dimensional inverse opal hydrogel for pH sensing.

PubMed

Xue, Fei; Meng, Zihui; Qi, Fenglian; Xue, Min; Wang, Fengyan; Chen, Wei; Yan, Zequn

2014-12-07

A novel hydrogel film with a highly ordered macropore monolayer on its surface was prepared by templated photo-polymerization of hydrogel monomers on a two-dimensional (2D) polystyrene colloidal array. The 2D inverse opal hydrogel has prominent advantages over traditional three-dimensional (3D) inverse opal hydrogels. First, the formation of the 2D array template through a self-assembly method is considerably faster and simpler. Second, the stable ordering structure of the 2D array template makes it easier to introduce the polymerization solution into the template. Third, a simple measurement, a Debye diffraction ring, is utilized to characterize the neighboring pore spacing of the 2D inverse opal hydrogel. Acrylic acid was copolymerized into the hydrogel; thus, the hydrogel responded to pH through volume change, which resulted from the formation of the Donnan potential. The 2D inverse opal hydrogel showed that the neighboring pore spacing increased by about 150 nm and diffracted color red-shifted from blue to red as the pH increased from pH 2 to 7. In addition, the pH response kinetics and ionic strength effect of this 2D mesoporous polymer film were also investigated.

The hydrothermolysis of the picrate anion: Kinetics and mechanism

USGS Publications Warehouse

Ross, D.S.; Jayaweera, I.

2002-01-01

The hydrothermolysis of the picrate anion in aqueous solution has been studied at 260-325??C in liquid water. At starting pH values above 12, the disappearance of picrate begins immediately and is first order in OH-. At lower pH, there is an induction period preceding the disappearance, and over the pH range 6.7-11.9 there is no pH dependence in the developed reaction phase. Added borate and silicate salts promote the reaction, suggesting their acting as nucleophiles at hydrothermal conditions. Nitrite is an initial product, while acetate is a final product and reflective of a vigorous oxidative sequence consuming the intermediate products. A reaction sequence consistent with the results at the lower pH includes initiation of a chain process by displacement of nitrite by water, followed by nucleophilic displacement of nitrite by nitrite such that a nitro group is replaced by an O-N=O group. The ester then rapidly hydrolyzes, and the net reaction is the production of an additional nitrite with each cycle. A simple modeling of this system satisfactorily fits the experimental findings. ?? 2002 Elsevier Science B.V. All rights reserved.

Determination of charge-carrier diffusion length in the photosensing layer of HgCdTe n-on-p photovoltaic infrared focal plane array detectors

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

Vishnyakov, A. V.; Stuchinsky, V. A., E-mail: stuchin@isp.nsc.ru; Brunev, D. V.

2014-03-03

In the present paper, we propose a method for evaluating the bulk diffusion length of minority charge carriers in the photosensing layer of photovoltaic focal plane array (FPA) photodetectors. The method is based on scanning a strip-shaped illumination spot with one of the detector diodes at a low level of photocurrents j{sub ph} being registered; such scanning provides data for subsequent analysis of measured spot-scan profiles within a simple diffusion model. The asymptotic behavior of the effective (at j{sub ph} ≠ 0) charge-carrier diffusion length l{sub d} {sub eff} as a function of j{sub ph} for j{sub ph} → 0 inferred frommore » our experimental data proved to be consistent with the behavior of l{sub d} {sub eff} vs j{sub ph} as predicted by the model, while the obtained values of the bulk diffusion length of minority carriers (electrons) in the p-HgCdTe film of investigated HgCdTe n-on-p FPA photodetectors were found to be in a good agreement with the previously reported carrier diffusion-length values for HgCdTe.« less

Metabolic Study of Cancer Cells Using a pH Sensitive Hydrogel Nanofiber Light Addressable Potentiometric Sensor.

PubMed

Shaibani, Parmiss Mojir; Etayash, Hashem; Naicker, Selvaraj; Kaur, Kamaljit; Thundat, Thomas

2017-01-27

We report a simple, fast, and cost-effective approach that measures cancer cell metabolism and their response to anticancer drugs in real time. Using a Light Addressable Potentiometric Sensor integrated with pH sensitive hydrogel nanofibers (NF-LAPS), we detect localized changes in pH of the media as cancer cells consume glucose and release lactate. NF-LAPS shows a sensitivity response of 74 mV/pH for cancer cells. Cancer cells (MDA MB231) showed a response of ∼0.4 unit change in pH compared to virtually no change observed for normal cells (MCF10A). We also observed a drop in pH for the multidrug-resistant cancer cells (MDA-MB-435MDR) in the presence of doxorubicin. However, inhibition of the metabolic enzymes such as hexokinase and lactate dehydrogenase-A suggested an improvement in the efficacy of doxorubicin by decreasing the level of acidification. This approach, based on extracellular acidification, enhances our understanding of cancer cell metabolic modes and their response to chemotherapies, which will help in the development of better treatments, including choice of drugs and dosages.

Nanoparticle assembled microcapsules for application as pH and ammonia sensor.

PubMed

Amali, Arlin Jose; Awwad, Nour H; Rana, Rohit Kumar; Patra, Digambara

2011-12-05

The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8-8.0, and can be successfully applied for the determination of ammonia in the concentration range 0-1.2 mM, which is important for aquatic life and the environment. Copyright © 2011 Elsevier B.V. All rights reserved.

The titration of carboxyl-terminated monolayers revisited: in situ calibrated fourier transform infrared study of well-defined monolayers on silicon.

PubMed

Aureau, D; Ozanam, F; Allongue, P; Chazalviel, J-N

2008-09-02

The acid-base equilibrium at the surface of well-defined mixed carboxyl-terminated/methyl-terminated monolayers grafted on silicon (111) has been investigated using in situ calibrated infrared spectroscopy (attenuated total reflectance (ATR)) in the range of 900-4000 cm (-1). Spectra of surfaces in contact with electrolytes of various pH provide a direct observation of the COOH <--> COO (-) conversion process. Quantitative analysis of the spectra shows that ionization of the carboxyl groups starts around pH 6 and extends over more than 6 pH units: approximately 85% ionization is measured at pH 11 (at higher pH, the layers become damaged). Observations are consistently accounted for by a single acid-base equilibrium and discussed in terms of change in ion solvation at the surface and electrostatic interactions between surface charges. The latter effect, which appears to be the main limitation, is qualitatively accounted for by a simple model taking into account the change in the Helmholtz potential associated with the surface charge. Furthermore, comparison of calculated curves with experimental titration curves of mixed monolayers suggests that acid and alkyl chains are segregated in the monolayer.

Development of a high-throughput liquid state assay for lipase activity using natural substrates and rhodamine B.

PubMed

Zottig, Ximena; Meddeb-Mouelhi, Fatma; Beauregard, Marc

2016-03-01

A fluorescence-based assay for the determination of lipase activity using rhodamine B as an indicator, and natural substrates such as olive oil, is described. It is based on the use of a rhodamine B-natural substrate emulsion in liquid state, which is advantageous over agar plate assays. This high-throughput method is simple and rapid and can be automated, making it suitable for screening and metagenomics application. Reaction conditions such as pH and temperature can be varied and controlled. Using triolein or olive oil as a natural substrate allows monitoring of lipase activity in reaction conditions that are closer to those used in industrial settings. The described method is sensitive over a wide range of product concentrations and offers good reproducibility. Copyright © 2015 Elsevier Inc. All rights reserved.

21 CFR 114.90 - Methodology.

Code of Federal Regulations, 2011 CFR

2011-04-01

... buffer. First standardize the electrodes using a pH 4.0 buffer at or near 25 °C. Standardization control..., the optimum being 25 °C. Any temperature determinations made without meter compensation may affect pH... approximately ±0.01 pH unit and a reproducibility of ±0.005 pH units. (4) General procedure for determining pH...

21 CFR 114.90 - Methodology.

Code of Federal Regulations, 2010 CFR

2010-04-01

... buffer. First standardize the electrodes using a pH 4.0 buffer at or near 25 °C. Standardization control..., the optimum being 25 °C. Any temperature determinations made without meter compensation may affect pH... approximately ±0.01 pH unit and a reproducibility of ±0.005 pH units. (4) General procedure for determining pH...

Electrostatics Control Actin Filament Nucleation and Elongation Kinetics*

PubMed Central

Crevenna, Alvaro H.; Naredi-Rainer, Nikolaus; Schönichen, André; Dzubiella, Joachim; Barber, Diane L.; Lamb, Don C.; Wedlich-Söldner, Roland

2013-01-01

The actin cytoskeleton is a central mediator of cellular morphogenesis, and rapid actin reorganization drives essential processes such as cell migration and cell division. Whereas several actin-binding proteins are known to be regulated by changes in intracellular pH, detailed information regarding the effect of pH on the actin dynamics itself is still lacking. Here, we combine bulk assays, total internal reflection fluorescence microscopy, fluorescence fluctuation spectroscopy techniques, and theory to comprehensively characterize the effect of pH on actin polymerization. We show that both nucleation and elongation are strongly enhanced at acidic pH, with a maximum close to the pI of actin. Monomer association rates are similarly affected by pH at both ends, although dissociation rates are differentially affected. This indicates that electrostatics control the diffusional encounter but not the dissociation rate, which is critical for the establishment of actin filament asymmetry. A generic model of protein-protein interaction, including electrostatics, explains the observed pH sensitivity as a consequence of charge repulsion. The observed pH effect on actin in vitro agrees with measurements of Listeria propulsion in pH-controlled cells. pH regulation should therefore be considered as a modulator of actin dynamics in a cellular environment. PMID:23486468

Behavior responses of Drunella coloradensis (Ephemeroptera) nymphs to short-term pH reductions

Treesearch

Christopher M. Pennuto; Frank deNoyelles

1993-01-01

Behavioral responses of Drunella coloradensis nymphs were examined in outdoor experimental stream channels after pH reductions of 7 and 2 pH units below ambient. The severity of pH decline below the ambient of 7.8 influenced the behavior patterns displayed by nymphs. At pH 7.01 (an intermediate pH decline) nymphs sat less frequently and burrowed more than controls....

The use of valinomycin, nigericin and trichlorocarbanilide in control of the protonmotive force in Escherichia coli cells.

PubMed

Ahmed, S; Booth, I R

1983-04-15

Valinomycin, nigericin and trichlorocarbanilide were assessed for their ability to control the protonmotive force in Escherichia coli cells. Valinomycin, at high K+ concentrations, was found to decrease the membrane potential delta phi and indirectly to decrease the pH gradient delta pH. Nigericin was found to have two modes of action. At low concentrations (0.05-2 microM) it carried out K+/H+ exchange and decreased delta pH. At higher concentrations (50 microM) it carried out a K+-dependent transfer of H+, decreasing both delta phi and delta pH. In EDTA-treated cells only the latter mode of action was evident, whereas in a mutant sensitive to deoxycholate both types of effect were observed. Trichlorocarbanilide is proposed as an alternative to nigericin for the specific control of delta pH, and it can be used in cells not treated with EDTA.

[Relationship between blood glucose levels and salivary pH and buffering capacity in type II diabetes patients].

PubMed

Elkafri, I H; Mashlah, A; Shaqifa, A

2014-03-13

This study was evaluated the relationship between blood glucose levels and salivary pH and buffering capacity in type II diabetic patients. The sample comprised 210 participants (age ranged 40-60 years). Based on fasting blood glucose levels the participants were divided into 3 groups: controls with normal blood glucose levels; diabetic patients with levels ≤ 200 mg/dL; and diabetic patients with levels > 200 mg/dL. Salivary pH and buffering capacity were determined in a sample of resting (non-stimulated) saliva taken from each participant. Salivary pH levels in diabetic patients with blood glucose levels > 200 mg/dL were lower than in the controls and diabetic patients with levels ≤ 200 mg/dL. Salivary pH levels were comparable in controls and diabetic patients with blood glucose levels ≤ 200 mg/dL. Salivary buffering capacity in the 3 groups was comparable.

Bacterial community dynamics in a rumen fluid bioreactor during in-vitro cultivation.

PubMed

Zapletalová, Martina; Kašparovská, Jitka; Křížová, Ludmila; Kašparovský, Tomáš; Šerý, Omar; Lochman, Jan

2016-09-20

To study the various processes in the rumen the in vitro techniques are widely used to realize more controlled and reproducible conditions compared to in vivo experiments. Mostly, only the parameters like pH changes, volatile fatty acids content or metabolite production are monitored. In this study we examine the bacterial community dynamics of rumen fluid in course of ten day cultivation realize under standard conditions described in the literature. Whereas the pH values, total VFA content and A/P ratio in bioreactor were consistent with natural conditions in the rumen, the mean redox-potential values of -251 and -243mV were much more negative. For culture-independent assessment of bacterial community composition, the Illumina MiSeq results indicated that the community contained 292 bacterial genera. In course of ten days cultivation a significant changes in the microbial community were measured when Bacteroidetes to Firmicutes ratio changed from 3.2 to 1.2 and phyla Proteobacteria and Actinobacteria represented by genus Bifidobacterium and Olsenella significantly increased. The main responsible factor of these changes seems to be very low redox potential in bioreactor together with accumulation of simple carbohydrates in milieu as a result of limited excretion of fermented feed and absence of nutrient absorbing mechanisms. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of three Aconitum alkaloids in six herbal medicines by high-performance liquid chromatography.

PubMed

Kang, Xue-Qin; Fan, Zhi-Chao; Zhang, Zhi-Qi

2010-11-01

To simultaneously determine three components of aconitine, mesaconitine, and hypaconitine in six species of Aconitum genus, an extraction condition for the total alkaloids was specifically optimized and a simple analytical method of reversed-phased highperformance liquid chromatography (HPLC) was developed. The extraction rate of total alkaloids in A. szechenyianum Gay was 98.3% for repeated extracting three times with an acidic alcohol solution (alcohol: pH 3.0 HAc = 85:15, v/v). The chromatography was carried out on a Phenomenex Luna C(18) column by gradient elution with a mobile phase of 0.03 mol/mL ammonium bicarbonate (pH = 9.50) -acetonitrile at a flow rate of 1.0 mL/min. The method for all three alkaloids had good linear relationships (r > 0.999) in the concentration range of 1.0-200.0 μg/mL. The average recoveries were 96.6-103.1%, and the LOQ and LOD were in the range of 25-37 ng/mL and 9-12 ng/mL, respectively. The quantitative results indicated that contents of the three alkaloids varied significantly among crude aconite roots, so quality control of traditional Chinese medicines containing aconite roots should be taken into account.

Chlorhexidine-calcium phosphate nanoparticles - Polymer mixer based wound healing cream and their applications.

PubMed

Viswanathan, Kaliyaperumal; Monisha, P; Srinivasan, M; Swathi, D; Raman, M; Dhinakar Raj, G

2016-10-01

In this work, we developed a wound healing cream composed of two different polymers, namely chitosan and gelatin with chlorhexidine along with calcium phosphate nanoparticles. The physicochemical properties of the prepared cream were investigated based on SEM, EDX, Raman, FTIR and the results indicated that the cream contained gelatin, chitosan, calcium phosphate nanoparticles and chlorhexidine. The maximum swelling ratio studies indicated that the ratio was around of 52±2.2 at pH7.4 and the value was increased in acidic and alkaline pH. The antimicrobial activity was tested against bacteria and the results indicated that, both chlorhexidine and the hybrid cream devoid of chlorhexidine exhibited antimicrobial activity but the chlorhexidine impregnated cream showed three fold higher antimicrobial activity than without chlorhexidine. In vivo wound healing promoting activities of hybrid cream containing 0.4mg/L chlorhexidine were evaluated on surgically induced dermal wounds in mice. The results indicated that the cream with incorporated chlorhexidine significantly enhanced healing compared with the control samples. For the field validations, the veterinary clinical animals were treated with the cream and showed enhanced healing capacity. In conclusion, a simple and efficient method for design of a novel wound healing cream has been developed for veterinary applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Low pH and calcium effects on net Na+ and K+ fluxes in two catfish species from the Amazon River (Corydoras: Callichthyidae).

PubMed

Matsuo, A Y; Val, A L

2002-03-01

The present study analyzes Na+ and K+ disturbances caused by low pH in two catfish species from the Amazon River. Corydoras adolfoi inhabits ion-poor, black-stained, low pH (3.5-4.0) waters, while C. schwartzi is native to ion-rich waters at circumneutral pH. Fish were exposed to pH 3.5 Ca2+-free, and Ca2+-enriched (approximately 500 micromol/l) water to determine the protective effects of calcium. Net Na+ and K+ fluxes were measured in the water collected from the fish experimental chambers. C. adolfoi was unable to control the Na+ efflux at low pH, exhibiting Na+ loss up to -594 +/- 84 nmol g(-1) h(-1) during the first hour. After 3 and 6 h, net Na+ flux increased by 7- and 23-fold, respectively. In C. schwartzi, at pH 3.5, the initial high Na+ loss (-1,063 +/- 73 nmol g(-1) h(-1)) was gradually attenuated. A K+ loss occurred in both species, but remained relatively constant throughout exposure. High [Ca2+] affected ion losses in both species. C. adolfoi had 70% loss attenuation, indicating incapacity to control Na+ efflux. In C. schwartzi, elevated [Ca2+] completely prevented the Na+ losses caused by exposure to low pH. Rather different patterns were seen for K+ fluxes, with C. adolfoi showing no K+ disruption when exposed to low pH/high [Ca2+]. Thus, C. adolfoi loses Na+ during acid exposure, but has the ability to control K+ loss, while C. schwartzi controls diffusive Na+ loss but exhibits a slightly higher K+ loss. Ion balance was influenced by [Ca2+] at low pH in C. schwartzi but not in C. adolfoi.

Pragmatic prevention of preterm birth and evidence based medicine.

PubMed

Hoyme, Udo B

2016-07-01

Effective prevention of preterm birth is one of the unsolved problems in modern medicine. In the Thuringia campaign 2000 based on a simple screening with intravaginal pH self-measurements, adequate medical diagnosis and immediate antimicrobial therapy of genital infection, the rate of newborns <1000 g was reduced to 0.38 %, the lowest incidence ever seen in any of the German states. Therefore, the regime should be implicated as a necessary step of optimizing and rationalizing the health care system. However, in the discussion we had to learn that the best way to inhibit progress is to cope with problems by preferring the most complicated policies under persistent renunciation of simple solutions. As long as we do not have other alternative safe, simple and cheap methods, do we really have to wait even more decades to come for a prospectively randomized double-blinded almost impracticable study to convince the latest skeptical scientist that we have plenty of evidence-based means to reduce the incidence of premature birth, now, by decreasing infectious morbidity in pregnancy and by the same action childbed fever as well? Insisting scholastically on nothing but the 100 % pure evidence sometimes can hamper innovations and potential benefit. Would a similar caution ever had allowed us for instance to introduce handwashing according to Semmelweis? Good news, the Government of the State of Thuringia has decided this year to reestablish a pH selfcare screening programme.

Abiotic versus biotic drivers of ocean pH variation under fast sea ice in McMurdo Sound, Antarctica.

PubMed

Matson, Paul G; Washburn, Libe; Martz, Todd R; Hofmann, Gretchen E

2014-01-01

Ocean acidification is expected to have a major effect on the marine carbonate system over the next century, particularly in high latitude seas. Less appreciated is natural environmental variation within these systems, particularly in terms of pH, and how this natural variation may inform laboratory experiments. In this study, we deployed sensor-equipped moorings at 20 m depths at three locations in McMurdo Sound, comprising deep (bottom depth>200 m: Hut Point Peninsula) and shallow environments (bottom depth ∼25 m: Cape Evans and New Harbor). Our sensors recorded high-frequency variation in pH (Hut Point and Cape Evans only), tide (Cape Evans and New Harbor), and water mass properties (temperature and salinity) during spring and early summer 2011. These collective observations showed that (1) pH differed spatially both in terms of mean pH (Cape Evans: 8.009±0.015; Hut Point: 8.020±0.007) and range of pH (Cape Evans: 0.090; Hut Point: 0.036), and (2) pH was not related to the mixing of two water masses, suggesting that the observed pH variation is likely not driven by this abiotic process. Given the large daily fluctuation in pH at Cape Evans, we developed a simple mechanistic model to explore the potential for biotic processes--in this case algal photosynthesis--to increase pH by fixing carbon from the water column. For this model, we incorporated published photosynthetic parameters for the three dominant algal functional groups found at Cape Evans (benthic fleshy red macroalgae, crustose coralline algae, and sea ice algal communities) to estimate oxygen produced/carbon fixed from the water column underneath fast sea ice and the resulting pH change. These results suggest that biotic processes may be a primary driver of pH variation observed under fast sea ice at Cape Evans and potentially at other shallow sites in McMurdo Sound.

Abiotic versus Biotic Drivers of Ocean pH Variation under Fast Sea Ice in McMurdo Sound, Antarctica

PubMed Central

Matson, Paul G.; Washburn, Libe; Martz, Todd R.; Hofmann, Gretchen E.

2014-01-01

Ocean acidification is expected to have a major effect on the marine carbonate system over the next century, particularly in high latitude seas. Less appreciated is natural environmental variation within these systems, particularly in terms of pH, and how this natural variation may inform laboratory experiments. In this study, we deployed sensor-equipped moorings at 20 m depths at three locations in McMurdo Sound, comprising deep (bottom depth>200 m: Hut Point Peninsula) and shallow environments (bottom depth ∼25 m: Cape Evans and New Harbor). Our sensors recorded high-frequency variation in pH (Hut Point and Cape Evans only), tide (Cape Evans and New Harbor), and water mass properties (temperature and salinity) during spring and early summer 2011. These collective observations showed that (1) pH differed spatially both in terms of mean pH (Cape Evans: 8.009±0.015; Hut Point: 8.020±0.007) and range of pH (Cape Evans: 0.090; Hut Point: 0.036), and (2) pH was not related to the mixing of two water masses, suggesting that the observed pH variation is likely not driven by this abiotic process. Given the large daily fluctuation in pH at Cape Evans, we developed a simple mechanistic model to explore the potential for biotic processes – in this case algal photosynthesis – to increase pH by fixing carbon from the water column. For this model, we incorporated published photosynthetic parameters for the three dominant algal functional groups found at Cape Evans (benthic fleshy red macroalgae, crustose coralline algae, and sea ice algal communities) to estimate oxygen produced/carbon fixed from the water column underneath fast sea ice and the resulting pH change. These results suggest that biotic processes may be a primary driver of pH variation observed under fast sea ice at Cape Evans and potentially at other shallow sites in McMurdo Sound. PMID:25221950

Variability of exhaled breath condensate pH in lung transplant recipients.

PubMed

Czebe, Krisztina; Kullmann, Tamas; Csiszer, Eszter; Barat, Erzsebet; Horvath, Ildiko; Antus, Balazs

2008-01-01

Measurement of pH in exhaled breath condensate (EBC) may represent a novel method for investigating airway pathology. The aim of this longitudinal study was to assess the variability of EBC pH in stable lung transplant recipients (LTR). During routine clinical visits 74 EBC pH measurements were performed in 17 LTR. EBC pH was also measured in 19 healthy volunteers on four separate occasions. EBC pH was determined at standard CO2 partial pressure by a blood gas analyzer. Mean EBC pH in clinically stable LTR and in controls was similar (6.38 +/- 0.09 vs. 6.44 +/- 0.16; p = nonsignificant). Coefficient of variation for pH in LTR and controls was 2.1 and 2.3%, respectively. The limits of agreement for between-visit variability determined by the Bland-Altman test in LTR and healthy volunteers were also comparable (-0.29 and 0.46 vs. -0.53 and 0.44). Our data suggest that the variability of EBC pH in stable LTR is relatively small, and it is similar to that in healthy nontransplant subjects.

Enhancement of hydrogen production during waste activated sludge anaerobic fermentation by carbohydrate substrate addition and pH control.

PubMed

Chen, Yinguang; Xiao, Naidong; Zhao, Yuxiao; Mu, Hui

2012-06-01

The effects of carbohydrate/protein ratio (CH/Pr) and pH on hydrogen production from waste activated sludge (WAS) were investigated. Firstly, the optimal pH value for hydrogen production was influenced by the CH/Pr ratio, which was pH 10, 9, 8, 8, 8 and 6 at the CH/Pr ratio (COD based) of 0.2 (sole sludge), 1, 2.4, 3.8, 5 and 6.6, respectively. The maximal hydrogen production (100.6 mL/g-COD) was achieved at CH/Pr of 5 and pH 8, which was due to the synergistic effect of carbohydrate addition on hydrogen production, the enhancement of sludge protein degradation and protease and amylase activities, and the suitable fermentation pathway for hydrogen production. As hydrogen consumption was observed at pH 8, in order to further increase hydrogen production a two-step pH control strategy (pH 8+pH 10) was developed and the hydrogen production was further improved by 17.6%. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enrichment of a mixed microbial culture for polyhydroxyalkanoates production: Effect of pH and N and P concentrations.

PubMed

Montiel-Jarillo, Gabriela; Carrera, Julián; Suárez-Ojeda, María Eugenia

2017-04-01

Polyhydroxyalkanoates (PHA) are biopolymers that can be an alternative against conventional plastics. The study reported herein evaluated the enrichment of a mixed microbial culture (MMC) operated under feast/famine regime and different pHs in a sequencing batch reactor (SBR) using acetate as sole carbon source to produce polyhydroxyalkanoates (PHAs). The enrichment step was evaluated at controlled pH of 7.5 and also without pH control (averaged value of 9.0). The acetate uptake rate (-q S ) of both enrichments at the end of the experimental period exhibited similar behaviour being about 0.18CmolAcCmolX -1 h -1 and 0.19CmolAcCmolX -1 h -1 for SBR-A and SBR-B, respectively. However, the PHA-storing capacity of the biomass enriched without pH control was better, exhibiting a maximum PHA content of 36% (gPHAg -1 VSS) with a PHA production rate (q PHA ) of 0.16CmolPHACmolX -1 h -1 . Batch experiments were performed to evaluate PHA-storing capacity of the enriched culture at different pHs and nutrients concentrations. In the pH experiments (without nutrient limitation), it was found that in the absence of controlled pH, the enriched biomass exhibited a PHA content of 44% gPHAg -1 VSS with -q S and PHA to substrate yield (Y PHA/Ac ) of 0.57CmolAcCmolX -1 h -1 and 0.33CmolPHACmolAc -1 , respectively. Regarding the experiments at variable nutrients concentration (pH ranging 8.8 to 9.2), the results indicate that the PHA content in the enriched biomass is significantly higher being around 51% gPHAg -1 VSS under nitrogen limitation. This work demonstrated the feasibility of the enrichment of a MMC with PHA storage ability without pH control. Results also suggest that better PHAs contents and substrate uptake rates are obtained without controlling the pH in the accumulation step. Finally, this work also highlights the importance of understanding the role of nutrients concentration during the accumulation step. Copyright © 2017 Elsevier B.V. All rights reserved.

Treatment for hydrazine-containing waste water solution

NASA Technical Reports Server (NTRS)

Yade, N.

1986-01-01

The treatment for waste solutions containing hydrazine is presented. The invention attempts oxidation and decomposition of hydrazine in waste water in a simple and effective processing. The method adds activated charcoal to waste solutions containing hydrazine while maintaining a pH value higher than 8, and adding iron salts if necessary. Then, the solution is aerated.

Simple Potentiometric Determination of Reducing Sugars

ERIC Educational Resources Information Center

Moresco, Henry; Sanson, Pedro; Seoane, Gustavo

2008-01-01

In this article a potentiometric method for reducing sugar quantification is described. Copper(II) ion reacts with the reducing sugar (glucose, fructose, and others), and the excess is quantified using a copper wire indicator electrode. In order to accelerate the kinetics of the reaction, working conditions such as pH and temperature must be…

A Simple and Accurate Method for Measuring Enzyme Activity.

ERIC Educational Resources Information Center

Yip, Din-Yan

1997-01-01

Presents methods commonly used for investigating enzyme activity using catalase and presents a new method for measuring catalase activity that is more reliable and accurate. Provides results that are readily reproduced and quantified. Can also be used for investigations of enzyme properties such as the effects of temperature, pH, inhibitors,…

pH fractionation and identification of proteins: comparing column isoelectric focusing vs liquid based focusing techniques

USDA-ARS?s Scientific Manuscript database

In order to understand how bacteria react and adapt to changes in the environment, it is necessary to identify the proteins the bacteria produces under different environmental conditions. However, the proteomes of even simple organisms like bacteria can contain a significant number of proteins, mak...

Validation of Student Generated Data for Assessment of Groundwater Quality

ERIC Educational Resources Information Center

Peckenham, John M.; Thornton, Teresa; Peckenham, Phoebe

2012-01-01

As part of a research project to evaluate the effects of sand and gravel mining on water quality, students were trained to analyze their own drinking water for simple quality indicators. Indicators analyzed were pH, conductivity, hardness, nitrate, chloride, and dissolved iron. Approximately 523 analyses were completed by students between 2006 and…

Dynamic Effects of Initial pH of Substrate on Biological Growth and Metamorphosis of Black Soldier Fly (Diptera: Stratiomyidae).

PubMed

Ma, Junhua; Lei, Yanyan; Rehman, Kashif Ur; Yu, Ziniu; Zhang, Jibin; Li, Wu; Li, Qing; Tomberlin, Jeffery K; Zheng, Longyu

2018-02-08

Edible insects have become a recognized alternative and sustainable source of high-quality proteins and fats for livestock or human consumption. In the production process of black soldier fly (BSF), (Hermetia illucens L. [Diptera: Stratiomyidae]), initial substrate pH is a critical parameter to ensure the best value of insect biomass, life history traits, and quality bio-fertilizer. This study examined the impact of initial pH values on BSF larvae production, development time, and adult longevity. The BSF were reared on artificial diet with initial pH of 2.0, 4.0, 6.0, 8.0, and 10.0; the control was set at 7.0. Final BSF larval weight was significantly greater in substrates having initial pH 6.0 (0.21 g), control 7.0 (0.20 g), and 10.0 (0.20 g) with no significant difference among them, whereas larval weight reared with initial pH 2.0 and 4.0 were lowest at 0.16 g (-23%). Prepupal weight was greatest when larvae were reared on substrates with initial pH 6.0 (0.18 g), control 7.0 (0.19 g), 8.0 (0.18 g), and 10.0 (0.18 g). In contrast, the prepupal weight of larvae reared on diets with initial pH 2.0 was lowest at 0.15 g (-22%). Larval development time was 21.19 d at pH 8.0, about 3 d (12.5%) shorter than that of those reared on diets with initial pH 6.0, 7.0 control, and 10.0. In all treatments, pH shifted to 5.7 after 3-4 d and 8.5 after 16-17 d except for two groups (2.0 and 4.0) where the pH remained slightly acidic 5.0 and 6.5, respectively. © The Author(s) 2018. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Stability of Metronidazole Suspensions.

PubMed

Donnelly, Ronald F; Ying, James

2015-01-01

Metronidazole is an antiprotozoal agent used in the treatment of bacterial and protozoal anaerobic infections. The objectives of this study were to develop concentrated metronidazole suspensions that are inexpensive and easy to prepare and determine the stability of these suspensions after storage in amber polyvinyl chloride bottles at room temperature (23°C) and under refrigeration (5°C). Metronidazole suspensions (50 mg/mL) were prepared from powder using Ora-Blend or simple syrup as the vehicles. Samples were collected in triplicate from each container on days 0, 7, 14, 28, 56, and 93. Samples were assayed using a high-performance liquid chromatography method that had been validated as stability indicating. Color, change in physical appearance, and pH were also monitored at each time interval. There was no apparent change in color or physical appearance. The pH values changed by less than 0.20 units over the 93 days. The stability of metronidazole suspensions compounded from United States Pharmacopeia powder using Ora-Blend or simple syrup and packaged in amber polyvinyl chloride bottles was determined to be 93 days when stored at either room temperature or under refrigeration.

Development of a fast and simple test system for the semiquantitative protein detection in cerebrospinal liquids based on gold nanoparticles.

PubMed

Göbel, Gero; Lange, Robert; Hollidt, Jörg-Michael; Lisdat, Fred

2016-01-01

The fast and simple detection of increased protein concentrations in cerebrospinal liquids is preferable in the emergency medicine and it can help to avoid unnecessary laboratory work by an early classification of neurological diseases. Here a test system is developed which is based on the electrostatic interaction between negatively charged gold nanoparticles and proteins at pH values around 5. The test system can be adjusted in such a way that protein/nanoparticles aggregates are formed leading to a red-shift in the absorption spectrum of the nanoparticles suspension. At concentrations above 500 mg/l the color of the suspension changes from red via violet toward blue in a rather small concentration range from 500 to 1000 mg/l. Furthermore the influence of various parameters such as gold nanoparticle concentration, pH value and varying ion concentration in the sample on the test system is examined. Finally cerebrospinal liquids of a larger number of patients have been analyzed. Copyright © 2015 Elsevier B.V. All rights reserved.

Exogenous lactobacilli mitigate microbial changes associated with grain fermentation (corn, oats, and wheat) by equine fecal microflora ex vivo.

PubMed

Harlow, Brittany E; Lawrence, Laurie M; Harris, Patricia A; Aiken, Glen E; Flythe, Michael D

2017-01-01

Cereal grains are often included in equine diets. When starch intake exceeds foregut digestion starch will reach the hindgut, impacting microbial ecology. Probiotics (e.g., lactobacilli) are reported to mitigate GI dysbioses in other species. This study was conducted to determine the effect of exogenous lactobacilli on pH and the growth of amylolytic and lactate-utilizing bacteria. Feces were collected from 3 mature geldings fed grass hay with access to pasture. Fecal microbes were harvested by differential centrifugation, washed, and re-suspended in anaerobic media containing ground corn, wheat, or oats at 1.6% (w/v) starch and one of five treatments: Control (substrate only), L. acidophilus, L. buchneri, L. reuteri, or an equal mixture of all three (107 cells/mL, final concentration). After 24 h of incubation (37°C, 160 rpm), samples were collected for pH and enumerations of total amylolytics, Group D Gram-positive cocci (GPC; Enterococci, Streptococci), lactobacilli, and lactate-utilizing bacteria. Enumeration data were log transformed prior to ANOVA (SAS, v. 9.3). Lactobacilli inhibited pH decline in corn and wheat fermentations (P < 0.0001). Specifically, addition of either L. reuteri or L. acidophilus was most effective at mitigating pH decline with both corn and wheat fermentation, in which the greatest acidification occurred (P < 0.05). Exogenous lactobacilli decreased amylolytics, while increasing lactate-utilizers in corn and wheat fermentations (P < 0.0001). In oat fermentations, L. acidophilus and L. reuteri inhibited pH decline and increased lactate-utilizers while decreasing amylolytics (P < 0.0001). For all substrates, L. reuteri additions (regardless of viability) had the lowest number of GPC and the highest number of lactobacilli and lactate-utilizers (P < 0.05). There were no additive effects when lactobacilli were mixed. Exogenous lactobacilli decreased the initial (first 8 h) rate of starch catalysis when wheat was the substrate, but did not decrease total (24 h) starch utilization in any case. These results indicate that exogenous lactobacilli can impact the microbial community and pH of cereal grain fermentations by equine fecal microflora ex vivo. Additionally, dead (autoclaved) exogenous lactobacilli had similar effects as live lactobacilli on fermentation. This latter result indicates that the mechanism by which lactobacilli impact other amylolytic bacteria is not simple resource competition.

Exogenous lactobacilli mitigate microbial changes associated with grain fermentation (corn, oats, and wheat) by equine fecal microflora ex vivo

PubMed Central

Harlow, Brittany E.; Lawrence, Laurie M.; Harris, Patricia A.; Aiken, Glen E.

2017-01-01

Cereal grains are often included in equine diets. When starch intake exceeds foregut digestion starch will reach the hindgut, impacting microbial ecology. Probiotics (e.g., lactobacilli) are reported to mitigate GI dysbioses in other species. This study was conducted to determine the effect of exogenous lactobacilli on pH and the growth of amylolytic and lactate-utilizing bacteria. Feces were collected from 3 mature geldings fed grass hay with access to pasture. Fecal microbes were harvested by differential centrifugation, washed, and re-suspended in anaerobic media containing ground corn, wheat, or oats at 1.6% (w/v) starch and one of five treatments: Control (substrate only), L. acidophilus, L. buchneri, L. reuteri, or an equal mixture of all three (107 cells/mL, final concentration). After 24 h of incubation (37°C, 160 rpm), samples were collected for pH and enumerations of total amylolytics, Group D Gram-positive cocci (GPC; Enterococci, Streptococci), lactobacilli, and lactate-utilizing bacteria. Enumeration data were log transformed prior to ANOVA (SAS, v. 9.3). Lactobacilli inhibited pH decline in corn and wheat fermentations (P < 0.0001). Specifically, addition of either L. reuteri or L. acidophilus was most effective at mitigating pH decline with both corn and wheat fermentation, in which the greatest acidification occurred (P < 0.05). Exogenous lactobacilli decreased amylolytics, while increasing lactate-utilizers in corn and wheat fermentations (P < 0.0001). In oat fermentations, L. acidophilus and L. reuteri inhibited pH decline and increased lactate-utilizers while decreasing amylolytics (P < 0.0001). For all substrates, L. reuteri additions (regardless of viability) had the lowest number of GPC and the highest number of lactobacilli and lactate-utilizers (P < 0.05). There were no additive effects when lactobacilli were mixed. Exogenous lactobacilli decreased the initial (first 8 h) rate of starch catalysis when wheat was the substrate, but did not decrease total (24 h) starch utilization in any case. These results indicate that exogenous lactobacilli can impact the microbial community and pH of cereal grain fermentations by equine fecal microflora ex vivo. Additionally, dead (autoclaved) exogenous lactobacilli had similar effects as live lactobacilli on fermentation. This latter result indicates that the mechanism by which lactobacilli impact other amylolytic bacteria is not simple resource competition. PMID:28358885

Apiaceous vegetable consumption decreases PhIP-induced DNA adducts and increases methylated PhIP metabolites in the urine metabolome in rats.

PubMed

Kim, Jae Kyeom; Gallaher, Daniel D; Chen, Chi; Yao, Dan; Trudo, Sabrina P

2015-03-01

Heterocyclic aromatic amines, such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), are carcinogenic compounds produced during heating of protein-containing foods. Apiaceous vegetables inhibit PhIP-activating enzymes, whereas cruciferous vegetables induce both PhIP-activating and -detoxifying enzymes. We investigated the effects of these vegetables, either alone or combined, on PhIP metabolism and colonic DNA adduct formation in rats. Male Wistar rats were fed cruciferous vegetables (21%, wt:wt), apiaceous vegetables (21%, wt:wt), or a combination of both vegetables (10.5% wt:wt of each). Negative and positive control groups were fed an AIN-93G diet. After 6 d, all groups received an intraperitoneal injection of PhIP (10 mg · kg body weight(-1)) except for the negative control group, which received only vehicle. Urine was collected for 24 h after the injection for LC-tandem mass spectrometry metabolomic analyses. On day 7, rats were killed and tissues processed. Compared with the positive control, cruciferous vegetables increased the activity of hepatic PhIP-activating enzymes [39.5% and 45.1% for cytochrome P450 (CYP) 1A1 (P = 0.0006) and CYP1A2 (P < 0.0001), respectively] and of uridine 5'-diphospho-glucuronosyltransferase 1A (PhIP-detoxifying) by 24.5% (P = 0.0267). Apiaceous vegetables did not inhibit PhIP-activating enzymes, yet reduced colonic PhIP-DNA adducts by 20.4% (P = 0.0496). Metabolomic analyses indicated that apiaceous vegetables increased the relative abundance of urinary methylated PhIP metabolites. The sum of these methylated metabolites inversely correlated with colonic PhIP-DNA adducts (r = -0.43, P = 0.01). We detected a novel methylated urinary PhIP metabolite and demonstrated that methylated metabolites are produced in the human liver S9 fraction. Apiaceous vegetables did not inhibit the activity of PhIP-activating enzymes in rats, suggesting that the reduction in PhIP-DNA adducts may involve other pathways. Further investigation of the importance of PhIP methylation in carcinogen metabolism is warranted, given the inverse correlation of methylated PhIP metabolites with a biomarker of carcinogenesis and the detection of a novel methylated PhIP metabolite. © 2015 American Society for Nutrition.

Apiaceous Vegetable Consumption Decreases PhIP-Induced DNA Adducts and Increases Methylated PhIP Metabolites in the Urine Metabolome in Rats123

PubMed Central

Kim, Jae Kyeom; Gallaher, Daniel D; Chen, Chi; Yao, Dan; Trudo, Sabrina P

2015-01-01

Background: Heterocyclic aromatic amines, such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), are carcinogenic compounds produced during heating of protein-containing foods. Apiaceous vegetables inhibit PhIP-activating enzymes, whereas cruciferous vegetables induce both PhIP-activating and -detoxifying enzymes. Objective: We investigated the effects of these vegetables, either alone or combined, on PhIP metabolism and colonic DNA adduct formation in rats. Methods: Male Wistar rats were fed cruciferous vegetables (21%, wt:wt), apiaceous vegetables (21%, wt:wt), or a combination of both vegetables (10.5% wt:wt of each). Negative and positive control groups were fed an AIN-93G diet. After 6 d, all groups received an intraperitoneal injection of PhIP (10 mg · kg body weight−1) except for the negative control group, which received only vehicle. Urine was collected for 24 h after the injection for LC–tandem mass spectrometry metabolomic analyses. On day 7, rats were killed and tissues processed. Results: Compared with the positive control, cruciferous vegetables increased the activity of hepatic PhIP-activating enzymes [39.5% and 45.1% for cytochrome P450 (CYP) 1A1 (P = 0.0006) and CYP1A2 (P < 0.0001), respectively] and of uridine 5′-diphospho-glucuronosyltransferase 1A (PhIP-detoxifying) by 24.5% (P = 0.0267). Apiaceous vegetables did not inhibit PhIP-activating enzymes, yet reduced colonic PhIP-DNA adducts by 20.4% (P = 0.0496). Metabolomic analyses indicated that apiaceous vegetables increased the relative abundance of urinary methylated PhIP metabolites. The sum of these methylated metabolites inversely correlated with colonic PhIP-DNA adducts (r = −0.43, P = 0.01). We detected a novel methylated urinary PhIP metabolite and demonstrated that methylated metabolites are produced in the human liver S9 fraction. Conclusions: Apiaceous vegetables did not inhibit the activity of PhIP-activating enzymes in rats, suggesting that the reduction in PhIP-DNA adducts may involve other pathways. Further investigation of the importance of PhIP methylation in carcinogen metabolism is warranted, given the inverse correlation of methylated PhIP metabolites with a biomarker of carcinogenesis and the detection of a novel methylated PhIP metabolite. PMID:25733458

HDP for the Neutralized pH Value Control in the Clarifying Process of Sugar Cane Juice

NASA Astrophysics Data System (ADS)

Lin, Xiaofeng; Yang, Jiaran

2009-05-01

Neutralizing pH value of sugar cane juice is the important craft in the control process in the clarifying process of sugar cane juice, which is the important factor to influence output and the quality of white sugar. On the one hand, it is an important content to control the neutralized pH value within a required range, which has the vital significance for acquiring high quality purified juice, reducing energy consumption and raising sucrose recovery. On the other hand, it is a complicated physical-chemistry process, which has the characteristics of strong non-linearity, time-varying, large time-delay, and multi-input. Therefore, there has not been a very good solution to control the neutralized pH value. Firstly, in this chapter, a neural network model for the clarifying process of sugar juice is established based on gathering 1200 groups of real-time sample data in a sugar factory. Then, the HDP (Heuristic Dynamic Programming) method is used to optimize and control the neutralized pH value in the clarifying process of sugar juice. Simulation results indicate that this method has good control effect. This will build a good foundation for stabilizing the clarifying process and enhancing the quality of the purified juice and lastly enhancing the quality of white sugar.

Surgical therapy in Barrett's esophagus.

PubMed Central

DeMeester, T R; Attwood, S E; Smyrk, T C; Therkildsen, D H; Hinder, R A

1990-01-01

Seventy-six patients with Barrett's esophagus were cared for during a 10-year period. Fifty-six patients (74%) presented with complications of the disease. There were 20 strictures, 7 giant ulcers, 11 cases of dysplasia, and 29 patients with carcinoma. In patients with benign disease, 93% had mechanically defective sphincters and 83% had peristaltic failure of the lower esophageal body. Esophageal pH monitoring showed excessive esophageal exposure to pH less than 4 in 93% and excessive exposure to pH more than 7 in 34% of the patients tested. Ninety-three per cent of patients with excessive alkaline exposure had complications, compared to only 44% with normal alkaline exposure (p less than 0.01). Gastric pH monitoring, serum gastrin levels, and gastric acid analysis supported a duodenal source for the alkaline exposure. Antireflux surgery was performed using Nissen fundoplication in 30, Belsey partial fundoplication in 3, and Collis-Belsey gastroplasty in 2. Six required resection with colon interposition. Good symptomatic control was achieved in 77% after antireflux surgery. Four patients had symptoms and signs of duodenogastric reflux; three required a bile diversion procedure. Fifteen patients had an en bloc curative resection with colon interposition. One patient with high-grade dysplasia on biopsy was found to have intramucosal carcinoma after simple esophagectomy. Five tumors were intramucosal, seven were intramural, and four were transmural. Lymph node involvement occurred only in the latter two. Actuarial survival 5 years after curative resection was 53%. Median survival time for patients after palliative resection or no resection was 12 months. Study of en bloc specimens indicated that extent of resection should be adapted to extent of disease: esophagectomy for intramucosal disease, en bloc esophagectomy with splenic preservation for intramural and transmural disease. Serum CEA was useful in detecting recurrent disease after surgery when the primary tumor stained positively for CEA. Images Figs. 11A-D. Figs. 11A-D. PMID:2222018

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

Tang, Guoping; Zheng, Jianqiu; Xu, Xiaofeng

Soil organic carbon turnover to CO 2 and CH 4 is sensitive to soil redox potential and pH conditions. But, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximatelymore » describe the observed pH evolution without additional parameterization. Though Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. Furthermore, the equilibrium speciation predicts a substantial increase in CO 2 solubility as pH increases, and taking into account CO 2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO 2 production from closed microcosms can be substantially underestimated based on headspace CO 2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions.« less

Biogeochemical modeling of CO2 and CH4 production in anoxic Arctic soil microcosms

NASA Astrophysics Data System (ADS)

Tang, Guoping; Zheng, Jianqiu; Xu, Xiaofeng; Yang, Ziming; Graham, David E.; Gu, Baohua; Painter, Scott L.; Thornton, Peter E.

2016-09-01

Soil organic carbon turnover to CO2 and CH4 is sensitive to soil redox potential and pH conditions. However, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximately describe the observed pH evolution without additional parameterization. Although Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. The equilibrium speciation predicts a substantial increase in CO2 solubility as pH increases, and taking into account CO2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO2 production from closed microcosms can be substantially underestimated based on headspace CO2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions.

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

DOE PAGES

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.; ...

2016-11-21

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Spatiotemporal pH dynamics in concentration polarization near ion-selective membranes.

PubMed

Andersen, Mathias B; Rogers, David M; Mai, Junyu; Schudel, Benjamin; Hatch, Anson V; Rempe, Susan B; Mani, Ali

2014-07-08

We present a detailed analysis of the transient pH dynamics for a weak, buffered electrolyte subject to voltage-driven transport through an ion-selective membrane. We show that pH fronts emanate from the concentration polarization zone next to the membrane and that these propagating fronts change the pH in the system several units from its equilibrium value. The analysis is based on a 1D model using the unsteady Poisson-Nernst-Planck equations with nonequilibrium chemistry and without assumptions of electroneutrality or asymptotically thin electric double layers. Nonequilibrium chemical effects, especially for water splitting, are shown to be important for the dynamical and spatiotemporal evolution of the pH fronts. Nonetheless, the model also shows that at steady state the assumption of chemical equilibrium can still lead to good approximations of the global pH distribution. Moreover, our model shows that the transport of the hydronium ion in the extended space charge region is governed by a balance between electromigration and water self-ionization. On the basis of this observation, we present a simple model showing that the net flux of the hydronium ion is proportional to the length of the extended space charge region and the water self-ionization rate. To demonstrate these effects in practice, we have adopted the experiment of Mai et al. (Mai, J.; Miller, H.; Hatch, A. V. Spatiotemporal Mapping of Concentration Polarization Induced pH Changes at Nanoconstrictions. ACS Nano 2012, 6, 10206) as a model problem, and by including the full chemistry and transport, we show that the present model can capture the experimentally observed pH fronts. Our model can, among other things, be used to predict and engineer pH dynamics, which can be essential to the performance of membrane-based systems for biochemical separation and analysis.

Interactions of calcium and fulvic acid at the goethite-water interface

NASA Astrophysics Data System (ADS)

Weng, Li Ping; Koopal, Luuk K.; Hiemstra, Tjisse; Meeussen, Johannes C. L.; Van Riemsdijk, Willem H.

2005-01-01

Interactions of calcium and fulvic acid (Strichen ) with the surface of goethite were studied with batch and titration experiments. The mutual influence of the interactions on the adsorption of fulvic acid, calcium ions and protons were examined. Adsorption of the fulvic acid to goethite decreased with increase in pH (pH range 3-11). Addition of Ca (1.0 mM) at intermediate and high pH significantly enhanced the adsorption of fulvic acid. Compared to the adsorption to pure goethite, the presence of fulvic acid enhanced the adsorption of Ca significantly. In comparison to the simple linear sum of Ca bound to fulvic acid and goethite, the interactions between goethite and fulvic acid led to a reduced adsorption of Ca at low pH and an enhanced adsorption at high pH. With the adsorption of fulvic acid, protons were released at low pH and coadsorbed at high pH. When Ca was added, fewer protons were released at low pH and fewer coadsorbed at high pH. The experimental results can be adequately described using a surface complexation model, the Ligand and Charge Distribution (LCD) model, in which the CD-MUSIC model for ion adsorption to mineral oxides and the NICA model for ion binding to humics are integrated. In the model calculations, adequate descriptions of the ternary system data (Ca-fulvic acid-goethite) were obtained with parameters derived from three binary systems (fulvic acid-goethite, Ca-goethite and Ca-fulvic acid) without further adjustment. The model calculations suggest that the interactions between Ca and fulvic acid at the surface of goethite are mainly due to the electrostatic effects.

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

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

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Optimization of food waste hydrolysis in leach bed coupled with methanogenic reactor: effect of pH and bulking agent.

PubMed

Xu, Su Yun; Lam, Hoi Pui; Karthikeyan, O Parthiba; Wong, Jonathan W C

2011-02-01

The effects of pH and bulking agents on hydrolysis/acidogenesis of food waste were studied using leach bed reactor (LBR) coupled with methanogenic up-flow anaerobic sludge blanket (UASB) reactor. The hydrolysis rate under regulated pH (6.0) was studied and compared with unregulated one during initial experiment. Then, the efficacies of five different bulking agents, i.e. plastic full particles, plastic hollow sphere, bottom ash, wood chip and saw dust were experimented under the regulated pH condition. Leachate recirculation with 50% water replacement was practiced throughout the experiment. Results proved that the daily leachate recirculation with pH control (6.0) accelerated the hydrolysis rate (59% higher volatile fatty acids) and methane production (up to 88%) compared to that of control without pH control. Furthermore, bottom ash improved the reactor alkalinity, which internally buffered the system that improved the methane production rate (0.182 l CH(4)/g VS(added)) than other bulking agents. Copyright © 2010 Elsevier Ltd. All rights reserved.

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

Immobilization of alpha-amylase from Bacillus circulans GRS 313 on coconut fiber.

PubMed

Dey, Gargi; Nagpal, Varima; Banerjee, Rintu

2002-01-01

A simple and inexpensive method for immobilizing alpha-amylase from Bacillus circulans GRS 313 on coconut fiber was developed. The immobilization conditions for highest efficiency were optimized with respect to immobilization pH of 5.5, 30 degrees C, contact time of 4 h, and enzyme to support a ratio of 1:1 containing 0.12 mg/mL of protein. The catalytic properties of the immobilized enzyme were compared with that of the free enzyme. The activity of amylase adsorbed on coconut fiber was 38.7 U/g of fiber at its optimum pH of 5.7 and 48 degrees C, compared with the maximum activity of 40.2 U/mL of free enzyme at the optimum pH of 4.9 and 48 degrees C. The reutilization capacity of the immobilized enzyme was up to three cycles.

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

Controlling composition and color characteristics of Monascus pigments by pH and nitrogen sources in submerged fermentation.

PubMed

Shi, Kan; Song, Da; Chen, Gong; Pistolozzi, Marco; Wu, Zhenqiang; Quan, Lei

2015-08-01

Submerged fermentations of Monascus anka were performed with different nitrogen sources at different pH in 3 L bioreactors. The results revealed that the Monascus pigments dominated by different color components (yellow pigments, orange pigments or red pigments) could be selectively produced through pH control and nitrogen source selection. A large amount of intracellular pigments dominated by orange pigments and a small amount of water-soluble extracellular yellow pigments were produced at low pH (pH 2.5 and 4.0), independently of the nitrogen source employed. At higher pH (pH 6.5), the role of the nitrogen source became more significant. In particular, when ammonium sulfate was used as nitrogen source, the intracellular pigments were dominated by red pigments with a small amount of yellow pigments. Conversely, when peptone was used, intracellular pigments were dominated by yellow pigments with a few red pigments derivatives. Neither the presence of peptone nor ammonium sulfate promoted the production of intracellular orange pigments while extracellular pigments with an orangish red color were observed in both cases, with a higher yield when peptone was used. Two-stage pH control fermentation was then performed to improve desirable pigments yield and further investigate the effect of pH and nitrogen sources on pigments composition. These results provide a useful strategy to produce Monascus pigments with different composition and different color characteristics. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Effects of acidifying ocean conditions on growth and survival of two life stages of the blue crab, Callinectes sapidus.

NASA Astrophysics Data System (ADS)

Giltz, S.; Taylor, C.

2016-02-01

Blue crabs, Callinectes sapidus, begin their larval phase offshore and circulate for approximately 30 days before settling near shore. As crabs transition to the juvenile stage, they move into coastal or estuarine environments characterized by lower salinity. Presently the average pH of the ocean is 8.1, 30% down from the beginning of the industrial revolution and is forecasted to drop to 7.8 by 2100. Decreasing pH causes dissolution of calcium carbonate shells, but the overall effects on crustaceans, such as blue crabs, are unknown. This study investigated the effect of a lower pH environment on the growth, survival, carapace hardness and molt frequency of larval and juvenile blue crabs in the Northern Gulf of Mexico. Larval crabs showed delayed growth under low pH (7.8) conditions compared to crabs in a control (present day) pH (8.1) environment. Population crashes (complete mortality) were experienced in 55% of the low pH aquaria but not in any of the control aquaria, suggesting that acidification poses a mortality risk. Under low pH conditions the intermolt duration decreased in juveniles, but the body length and weight did not differ from crabs raised in the control pH. Larvae (in tanks that did not crash) and juveniles did not experience increased mortality from a lower pH, but there do appear to be sublethal effects on growth and molting that differ between life history stages.

Influence of the hydrophilic head size and hydrophobic tail length of surfactants on the ability of micelles to stabilize citral.

PubMed

Hong, Chi Rac; Park, Sung Joon; Choi, Seung Jun

2016-07-01

Surfactant-made micelles can control the rate of chemical degradation of poorly water-soluble food flavors. To evaluate how the molecular structure of surfactant has an influence on the chemical decomposition rate of citral, micelles were prepared with polyoxyethylene alkyl ether-type surfactants that had similar molecular structures but various hydrophilic head sizes and hydrophobic tail lengths. At a critical 20× micelle concentration of surfactant, there was no significant difference in the chemical degradation rate of citral in micelles in neutral pH, regardless of the hydrophilic head size or hydrophobic tail length. In an acidic environment, the degradation rate constant of citral generally increased proportionally with increasing hydrophilic head size of surfactant (0.1563 and 0.2217 for surfactants with 23 and 100 oxyethylene units, respectively) but the length of hydrophobic tail did not affect the citral stability. Also, little difference (0.2217 and 0.2265 for surfactant having 100 oxyethylene units with and without Fe(3+) ) in degradation rate constant of citral between simple micellar solution and micellar solution containing iron suggested that iron ions could not accelerate citral degradation in micelles, regardless of the form of iron (Fe(2+) and Fe(3+) ). This work concludes that although the concentration of surfactant could be relevant, if its concentration could be controlled in the same manner as the critical micelle concentration, then a polyethylene alkyl ether-type surfactant with a small hydrophilic head could more efficiently stabilize citral at an acidic pH. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

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.

The synthesis and application of heparin-based smart drug carrier.

PubMed

Li, Qingxuan; Gan, Lu; Tao, Hong; Wang, Qian; Ye, Lin; Zhang, Aiying; Feng, Zengguo

2016-04-20

Heparin based polymer drug which could self-assemble into sphere micelle in water was firstly prepared by grafting paclitaxel (PTX) into the hydroxyl of heparin via aconitic bond as pH sensitive spacer. Positive charged drug DOX·HCl and cationic folic acid (CFA) can be further loaded into the polymer drug via electrostatic interaction in aqueous solution so as to prepare smart drug carrier. The drug carrier was able to release more PTX and DOX at pH 4.8 than that at pH 7.4, exhibiting pH sensitivity for two drugs. Furthermore, tumor cell cytotoxicity test proved it possessed significant cytotoxicity against tumor cells MDA-MB-231 as well as its active tumor targeting ability resulting from the loading of CFA. Cellular uptake and intracellular distribution were further revealed by confocal laser scanning microscopy (CLSM). In conclusion, this paper not only provided a simple strategy but also indicated heparin is a versatile platform for the design of smart drug carrier. The as-prepared drug carrier also showed promising potential in chemotherapy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modified release matrix prepared by compaction of spheres containing waxy material.

PubMed

Bado, L; Ghaly, E S

1995-09-01

In this study, chlorpheniramine maleate spheres were prepared by the extruder/marumerizer. A new waxy material, Gelucire 50/02 at three levels (10%, 30% and 50%) was added and Avicel PH-101 was used as spheronizing material. The drug was incorporated into the waxy material by two methods. The first was the direct method, in which the drug (10%), wax and Avicel PH-101 were mixed together. The second was the fusion method, in which the drug was dispersed in the melted wax and the solidified mass was milled and mixed with Avicel PH-101. The data obtained indicated that simple addition of waxy material into chlorpheniramine maleate-Avicel PH-101 spheres interrupted matrix formation and increased drug release. Also in this study, a multiparticulate delivery system was prepared successfully by compaction of spheres into tablets. Tablets compacted from spheres prepared by fusion method gave less drug release than those compacted from spheres of the same composition but prepared with direct method. As the level of wax was increased in tablet formulation, drug release was decreased.

pH Level as a Marker for Predicting Death among Patients with Vibrio vulnificus Infection, South Korea, 2000–2011

PubMed Central

Yun, Na Ra; Lee, Jun; Han, Mi Ah

2015-01-01

Vibrio vulnificus infection can progress to necrotizing fasciitis and death. To improve the likelihood of patient survival, an early prognosis of patient outcome is clinically important for emergency/trauma department doctors. To identify an accurate and simple predictor for death among V. vulnificus–infected persons, we reviewed clinical data for 34 patients at a hospital in South Korea during 2000–2011; of the patients, 16 (47%) died and 18 (53%) survived. For nonsurvivors, median time from hospital admission to death was 15 h (range 4–70). For predicting death, the areas under the receiver operating characteristic curves of the Acute Physiology and Chronic Health Evaluation (APACHE) II score and initial pH were 0.746 and 0.972, respectively (p = 0.005). An optimal cutoff pH of <7.35 had a sensitivity of 100% and specificity of 83%. Compared with the APACHE II score, the initial arterial blood pH level in V. vulnificus-infected patients was a more accurate predictive marker for death. PMID:25627847

pH level as a marker for predicting death among patients with Vibrio vulnificus infection, South Korea, 2000-2011.

PubMed

Yun, Na Ra; Kim, Dong-Min; Lee, Jun; Han, Mi Ah

2015-02-01

Vibrio vulnificus infection can progress to necrotizing fasciitis and death. To improve the likelihood of patient survival, an early prognosis of patient outcome is clinically important for emergency/trauma department doctors. To identify an accurate and simple predictor for death among V. vulnificus-infected persons, we reviewed clinical data for 34 patients at a hospital in South Korea during 2000-2011; of the patients, 16 (47%) died and 18 (53%) survived. For nonsurvivors, median time from hospital admission to death was 15 h (range 4-70). For predicting death, the areas under the receiver operating characteristic curves of the Acute Physiology and Chronic Health Evaluation (APACHE) II score and initial pH were 0.746 and 0.972, respectively (p = 0.005). An optimal cutoff pH of <7.35 had a sensitivity of 100% and specificity of 83%. Compared with the APACHE II score, the initial arterial blood pH level in V. vulnificus-infected patients was a more accurate predictive marker for death.

Functionalized Sugarcane Bagasse for U(VI) Adsorption from Acid and Alkaline Conditions.

PubMed

Su, Shouzheng; Liu, Qi; Liu, Jingyuan; Zhang, Hongsen; Li, Rumin; Jing, Xiaoyan; Wang, Jun

2018-01-15

The highly efficient removal of uranium from mine tailings effluent, radioactive wastewater and enrichment from seawater is of great significance for the development of nuclear industry. In this work, we prepared an efficient U(VI) adsorbent by EDTA modified sugarcane bagasse (MESB) with a simple process. The prepared adsorbent preserves high adsorptive capacity for UO 2 2+ (pH 3.0) and uranyl complexes, such as UO 2 (OH) + , (UO 2 ) 2 (OH) 2 2+ and (UO 2 ) 3 (OH) 5 + (pH 4.0 and pH 5.0) and good repeatability in acidic environment. The maximum adsorption capacity for U(VI) at pH 3.0, 4.0 and 5.0 is 578.0, 925.9 and 1394.1 mg/g and the adsorption capacity loss is only 7% after five cycles. With the pH from 3.0 to 5.0, the inhibitive effects of Na + and K + decreased but increased of Mg 2+ and Ca 2+ . MESB also exhibits good adsorption for [UO 2 (CO 3 ) 3 ] 4- at pH 8.3 from 10 mg/L to 3.3 μg/L. Moreover, MESB could effectively extract U(VI) from simulated seawater in the presence of other metals ions. This work provided a general and efficient uranyl enriched material for nuclear industry.

Spectrophotometric Calibration of pH Electrodes in Seawater Using Purified m-Cresol Purple

PubMed Central

2012-01-01

This work examines the use of purified meta-cresol purple (mCP) for direct spectrophotometric calibration of glass pH electrodes in seawater. The procedures used in this investigation allow for simple, inexpensive electrode calibrations over salinities of 20–40 and temperatures of 278.15–308.15 K without preparation of synthetic Tris seawater buffers. The optimal pH range is ∼7.0–8.1. Spectrophotometric calibrations enable straightforward, quantitative distinctions between Nernstian and non-Nernstian electrode behavior. For the electrodes examined in this study, both types of behavior were observed. Furthermore, calibrations performed in natural seawater allow direct determination of the influence of salinity on electrode performance. The procedures developed in this study account for salinity-induced variations in liquid junction potentials that, if not taken into account, would create pH inconsistencies of 0.028 over a 10-unit change in salinity. Spectrophotometric calibration can also be used to expeditiously determine the intercept potential (i.e., the potential corresponding to pH 0) of an electrode that has reliably demonstrated Nernstian behavior. Titrations to ascertain Nernstian behavior and salinity effects can be undertaken relatively infrequently (∼weekly to monthly). One-point determinations of intercept potential should be undertaken frequently (∼daily) to monitor for stable electrode behavior and ensure accurate potentiometric pH determinations. PMID:22463815

Living with pulmonary hypertension: unique insights from an international ethnographic study

PubMed Central

Kingman, Martha; Hinzmann, Barbara; Sweet, Oliver; Vachiéry, Jean-Luc

2014-01-01

Objectives To better understand the patient's perspective of pulmonary hypertension (PH), including the impact of living with PH, disease management and treatment. Design This qualitative ethnographic study collected observational video footage, supplemented by field notes and patient diaries to assess the impact of PH on the patient's life. Setting Patients were observed and filmed in their home for up to 6 h, capturing the environment, interactions and activities of everyday life. Participants Patients with pulmonary arterial hypertension (PAH) or chronic thromboembolic PH who were receiving PAH-specific medication were recruited through healthcare professionals (HCPs) and patient associations in seven countries across four continents. Sampling was purposive and subgroup analysis was not intended. Results Overall, 39 patients with PH were enrolled. Many patients had a poor understanding of PH and found their ‘invisible’ disease difficult to explain to others. An important finding was the secrecy surrounding PH. Feelings of insecurity and isolation were regularly reported, and many patients admitted to hiding their symptoms. The marked improvement in symptoms after therapy initiation made assessment of disease progression more difficult as patients compared their quality of life (QoL) against pretreatment levels. Extensive planning and adherence to daily routines were required in patients’ everyday life. Conclusions Ethnography was used for the first time, in several countries, to evaluate the patient's perception of living with PH. This approach revealed key findings that would not typically be uncovered using other qualitative techniques, including the secrecy surrounding PH, the difficulties in describing the disease and the challenges in assessing disease progression. A more tailored dissemination of information from HCPs and development of a simple and understandable PH definition may be beneficial in alleviating the secrecy reported by patients. A greater appreciation of how patients perceive their disease and QoL has the potential to improve PH management. PMID:24838724

Living with pulmonary hypertension: unique insights from an international ethnographic study.

PubMed

Kingman, Martha; Hinzmann, Barbara; Sweet, Oliver; Vachiéry, Jean-Luc

2014-05-16

To better understand the patient's perspective of pulmonary hypertension (PH), including the impact of living with PH, disease management and treatment. This qualitative ethnographic study collected observational video footage, supplemented by field notes and patient diaries to assess the impact of PH on the patient's life. Patients were observed and filmed in their home for up to 6 h, capturing the environment, interactions and activities of everyday life. Patients with pulmonary arterial hypertension (PAH) or chronic thromboembolic PH who were receiving PAH-specific medication were recruited through healthcare professionals (HCPs) and patient associations in seven countries across four continents. Sampling was purposive and subgroup analysis was not intended. Overall, 39 patients with PH were enrolled. Many patients had a poor understanding of PH and found their 'invisible' disease difficult to explain to others. An important finding was the secrecy surrounding PH. Feelings of insecurity and isolation were regularly reported, and many patients admitted to hiding their symptoms. The marked improvement in symptoms after therapy initiation made assessment of disease progression more difficult as patients compared their quality of life (QoL) against pretreatment levels. Extensive planning and adherence to daily routines were required in patients' everyday life. Ethnography was used for the first time, in several countries, to evaluate the patient's perception of living with PH. This approach revealed key findings that would not typically be uncovered using other qualitative techniques, including the secrecy surrounding PH, the difficulties in describing the disease and the challenges in assessing disease progression. A more tailored dissemination of information from HCPs and development of a simple and understandable PH definition may be beneficial in alleviating the secrecy reported by patients. A greater appreciation of how patients perceive their disease and QoL has the potential to improve PH management. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Effects of root medium pH on root water transport and apoplastic pH in red-osier dogwood (Cornus sericea) and paper birch (Betula papyrifera) seedlings.

PubMed

Zhang, W; Zwiazek, J J

2016-11-01

Soil pH is a major factor affecting plant growth. Plant responses to pH conditions widely vary between different species of plants. However, the exact mechanisms of high pH tolerance of plants are largely unknown. In the present study, we compared the pH responses of paper birch (Betula papyrifera) seedlings, a relatively sensitive species to high soil pH, with red-osier dogwood (Cornus sericea), reported to be relatively tolerant of high pH conditions. We examined the hypotheses that tolerance of plants to high root zone pH is linked to effective control of root apoplastic pH to facilitate nutrient and water transport processes In the study, we exposed paper birch and red-osier dogwood seedlings for six weeks to pH 5, 7 and 9 under controlled-environment conditions in hydroponic culture. Then, we measured biomass, gas exchange, root hydraulic conductivity, ferric chelate reductase (FCR) activity, xylem sap pH and the relative abundance of major elements in leaf protoplasts and apoplasts. The study sheds new light on the rarely studied high pH tolerance mechanisms in plants. We found that compared with paper birch, red-osier dogwood showed greater growth, higher gas exchange, and maintained higher root hydraulic conductivity as well as lower xylem sap pH under high pH conditions. The results suggest that the relatively high pH tolerance of dogwood is associated with greater water uptake ability and maintenance of low apoplastic pH. These traits may have a significant impact on the uptake of Fe and Mn by leaf cells. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Effects of a bacterial probiotic on ruminal pH and volatile fatty acids during subacute ruminal acidosis (SARA) in cattle.

PubMed

Goto, Hiroko; Qadis, Abdul Qadir; Kim, Yo-Han; Ikuta, Kentaro; Ichijo, Toshihiro; Sato, Shigeru

2016-11-01

Effects of a bacterial probiotic (BP) on ruminal fermentation and plasma metabolites were evaluated in four Holstein cattle (body weight, 645 ± 62 kg; mean ± SD) with induced subacute ruminal acidosis (SARA). SARA was induced by feeding a SARA-inducing diet, and thereafter, 20, 50 or 100 g per head of a commercial BP was administered for 7 consecutive days during the morning feeding. Cattle without BP served as the control. The 24-hr mean ruminal pH in the control was lower, whereas those in the BP groups administered 20 or 50 g were significantly higher compared to the control from days 2 to 7. Circadian patterns of the 1-hr mean ruminal pH were identical (6.4-6.8) among all cattle receiving BP. Although the mean minimum pH in the control on day -7 and day 0 was <5.8, the pH in the treatment groups on day 7 was >5.8 and significantly higher than that of the control group ( >5.2). Ruminal volatile fatty acid (VFA) concentrations were not affected by BP treatment; however, the BP groups had lower lactic acid levels compared with the control group at 20:00 on day 7. Additionally, non-esterified fatty acid levels decreased from 8:00 to 20:00 in all BP groups on day 7. These results suggest that administration of 20 to 50 g of a multi-strain BP for 7 days might improve the low pH and high lactic acid level of the ruminal fluid in SARA cattle.

LEAD AND COPPER CONTROL WITH NON-ZINC ORTHOPHOSPHATE

EPA Science Inventory

Successful application of orthophosphate formulations not containing zinc for achieving control of copper and lead corrosion requires careful consideration of the background water chemistry, particularly pH and DIC. Inhibitor performance is extremely dependent upon dosage and pH,...

Genetically encoded proton sensors reveal activity-dependent pH changes in neurons.

PubMed

Raimondo, Joseph V; Irkle, Agnese; Wefelmeyer, Winnie; Newey, Sarah E; Akerman, Colin J

2012-01-01

The regulation of hydrogen ion concentration (pH) is fundamental to cell viability, metabolism, and enzymatic function. Within the nervous system, the control of pH is also involved in diverse and dynamic processes including development, synaptic transmission, and the control of network excitability. As pH affects neuronal activity, and can also itself be altered by neuronal activity, the existence of tools to accurately measure hydrogen ion fluctuations is important for understanding the role pH plays under physiological and pathological conditions. Outside of their use as a marker of synaptic release, genetically encoded pH sensors have not been utilized to study hydrogen ion fluxes associated with network activity. By combining whole-cell patch clamp with simultaneous two-photon or confocal imaging, we quantified the amplitude and time course of neuronal, intracellular, acidic transients evoked by epileptiform activity in two separate in vitro models of temporal lobe epilepsy. In doing so, we demonstrate the suitability of three genetically encoded pH sensors: deGFP4, E(2)GFP, and Cl-sensor for investigating activity-dependent pH changes at the level of single neurons.

Mitochondrial matrix pH controls oxidative phosphorylation and metabolism-secretion coupling in INS-1E clonal beta cells.

PubMed

Akhmedov, Dmitry; Braun, Matthias; Mataki, Chikage; Park, Kyu-Sang; Pozzan, Tullio; Schoonjans, Kristina; Rorsman, Patrik; Wollheim, Claes B; Wiederkehr, Andreas

2010-11-01

Glucose-evoked mitochondrial signals augment ATP synthesis in the pancreatic β cell. This activation of energy metabolism increases the cytosolic ATP/ADP ratio, which stimulates plasma membrane electrical activity and insulin granule exocytosis. We have recently demonstrated that matrix pH increases during nutrient stimulation of the pancreatic β cell. Here, we have tested whether mitochondrial matrix pH controls oxidative phosphorylation and metabolism-secretion coupling in the rat β-cell line INS-1E. Acidification of the mitochondrial matrix pH by nigericin blunted nutrient-dependent respiratory and ATP responses (continuously monitored in intact cells). Using electrophysiology and single cell imaging, we find that the associated defects in energy metabolism suppress glucose-stimulated plasma membrane electrical activity and cytosolic calcium transients. The same parameters were unaffected after direct stimulation of electrical activity with tolbutamide, which bypasses mitochondrial function. Furthermore, lowered matrix pH strongly inhibited sustained, but not first-phase, insulin secretion. Our results demonstrate that the matrix pH exerts a control function on oxidative phosphorylation in intact cells and that this mode of regulation is of physiological relevance for the generation of downstream signals leading to insulin granule exocytosis. We propose that matrix pH serves a novel signaling role in sustained cell activation.

Outdoor cultures of Chlorella pyrenoidosa in the effluent of anaerobically digested activated sludge: The effects of pH and free ammonia.

PubMed

Tan, Xiao-Bo; Zhang, Ya-Lei; Yang, Li-Bin; Chu, Hua-Qiang; Guo, Jun

2016-01-01

A freshwater algae Chlorella pyrenoidosa was cultured outdoors using anaerobically digested activated sludge effluent. The effects of pH variations were evaluated. The coupled pH variations and free ammonia toxicity significantly affected the algal growth, lipids accumulation and contamination control during every season. The free ammonia toxicity at high pH levels actually inhibited the algal growth. Compared to an optimal algal growth at a pH of 5.7-6.5, biomass productivity at a high pH of 8.3-8.8 was reduced by 67.15±6.98%, 54.39±6.42% and 83.63±5.71% in the spring, fall and summer, respectively. When the pH rose above 9.1-9.6, algae were unable to grow in the wastewater. However, high pH levels reduced contamination (e.g., bacteria and microalgae grazers) and triggered lipids accumulation in algal cells. These findings suggest that pH control strategies are essential for this type of algal wastewater system, where ammonia is the dominant nitrogen source. Copyright © 2015 Elsevier Ltd. All rights reserved.

Defining a clinically meaningful effect for the design and interpretation of randomized controlled trials.

PubMed

Keefe, Richard S E; Kraemer, Helena C; Epstein, Robert S; Frank, Ellen; Haynes, Ginger; Laughren, Thomas P; McNulty, James; Reed, Shelby D; Sanchez, Juan; Leon, Andrew C

2013-05-01

This article captures the proceedings of a meeting aimed at defining clinically meaningful effects for use in randomized controlled trials for psychopharmacological agents. Experts from a variety of disciplines defined clinically meaningful effects from their perspectives along with viewpoints about how to design and interpret randomized controlled trials. The article offers relevant, practical, and sometimes anecdotal information about clinically meaningful effects and how to interpret them. The concept for this session was the work of co-chairs Richard Keefe and the late Andy Leon. Faculty included Richard Keefe, PhD; James McNulty, AbScB; Robert S. Epstein, MD, MS; Shelby D. Reed, PhD; Juan Sanchez, MD; Ginger Haynes, PhD; Andrew C. Leon, PhD; Helena Chmura Kraemer, PhD; Ellen Frank, PhD, and Kenneth L. Davis, MD. The term clinically meaningful effect is an important aspect of designing and interpreting randomized controlled trials but can be particularly difficult in the setting of psychopharmacology where effect size may be modest, particularly over the short term, because of a strong response to placebo. Payers, regulators, patients, and clinicians have different concerns about clinically meaningful effects and may describe these terms differently. The use of moderators in success rate differences may help better delineate clinically meaningful effects. There is no clear consensus on a single definition for clinically meaningful differences in randomized controlled trials, and investigators must be sensitive to specific concerns of stakeholders in psychopharmacology in order to design and execute appropriate clinical trials.

Controllable reflection properties of nanocomposite photonic crystals constructed by semiconductor nanocrystallites and natural periodic bio-matrices.

PubMed

Han, Jie; Su, Huilan; Song, Fang; Zhang, Di; Chen, Zhixin

2010-10-01

In this contribution, the subtle periodic nanostructures in butterfly wings and peacock feathers are applied as natural PhC matrices to in situ embed CdS nanocrystallites (nano-CdS) on the structure surface via a convenient solution process. The resulting nano-CdS/natural PhCs nanocomposites show typical 1D, quasi 1D and 2D PhC structures at the nanoscale, which is inherited from the corresponding natural periodic bio-matrices. Moreover, their reflection properties are investigated and show dependence on PhC type, structure parameter, loading amount, as well as collecting angle. This work suggests that natural periodic bio-structures could be perfect matrices to construct novel nanocomposite PhCs, whose photonic band structures are tunable and thus achieve controllable optical properties. Related ideas could inspire the design and synthesis of future nanocomposite PhCs.

Atomically-thin molecular layers for electrode modification of organic transistors

NASA Astrophysics Data System (ADS)

Gim, Yuseong; Kang, Boseok; Kim, Bongsoo; Kim, Sun-Guk; Lee, Joong-Hee; Cho, Kilwon; Ku, Bon-Cheol; Cho, Jeong Ho

2015-08-01

Atomically-thin molecular layers of aryl-functionalized graphene oxides (GOs) were used to modify the surface characteristics of source-drain electrodes to improve the performances of organic field-effect transistor (OFET) devices. The GOs were functionalized with various aryl diazonium salts, including 4-nitroaniline, 4-fluoroaniline, or 4-methoxyaniline, to produce several types of GOs with different surface functional groups (NO2-Ph-GO, F-Ph-GO, or CH3O-Ph-GO, respectively). The deposition of aryl-functionalized GOs or their reduced derivatives onto metal electrode surfaces dramatically enhanced the electrical performances of both p-type and n-type OFETs relative to the performances of OFETs prepared without the GO modification layer. Among the functionalized rGOs, CH3O-Ph-rGO yielded the highest hole mobility of 0.55 cm2 V-1 s-1 and electron mobility of 0.17 cm2 V-1 s-1 in p-type and n-type FETs, respectively. Two governing factors: (1) the work function of the modified electrodes and (2) the crystalline microstructures of the benchmark semiconductors grown on the modified electrode surface were systematically investigated to reveal the origin of the performance improvements. Our simple, inexpensive, and scalable electrode modification technique provides a significant step toward optimizing the device performance by engineering the semiconductor-electrode interfaces in OFETs.Atomically-thin molecular layers of aryl-functionalized graphene oxides (GOs) were used to modify the surface characteristics of source-drain electrodes to improve the performances of organic field-effect transistor (OFET) devices. The GOs were functionalized with various aryl diazonium salts, including 4-nitroaniline, 4-fluoroaniline, or 4-methoxyaniline, to produce several types of GOs with different surface functional groups (NO2-Ph-GO, F-Ph-GO, or CH3O-Ph-GO, respectively). The deposition of aryl-functionalized GOs or their reduced derivatives onto metal electrode surfaces dramatically enhanced the electrical performances of both p-type and n-type OFETs relative to the performances of OFETs prepared without the GO modification layer. Among the functionalized rGOs, CH3O-Ph-rGO yielded the highest hole mobility of 0.55 cm2 V-1 s-1 and electron mobility of 0.17 cm2 V-1 s-1 in p-type and n-type FETs, respectively. Two governing factors: (1) the work function of the modified electrodes and (2) the crystalline microstructures of the benchmark semiconductors grown on the modified electrode surface were systematically investigated to reveal the origin of the performance improvements. Our simple, inexpensive, and scalable electrode modification technique provides a significant step toward optimizing the device performance by engineering the semiconductor-electrode interfaces in OFETs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03307a

Using Visible Spectrophotometers and pH Measurements to Study Speciation in a Guided-Inquiry Laboratory

ERIC Educational Resources Information Center

Otto, William H.; Larive, Cynthia K.; Mason, Susan L.; Robinson, Janet B.; Heppert Joseph A.; Ellis, James D.

2005-01-01

An experiment to perform a simple initial investigation that illustrates concepts of speciation and equilibrium, using the instrument and chemical resources in the laboratory is presented. The investigation showed that the presence of multiple chemical species in a reaction mixture (phenol red solution) reflects the acid and base conditions…

Determination of Titratable Acidity in Wine Using Potentiometric, Conductometric, and Photometric Methods

ERIC Educational Resources Information Center

Volmer, Dietrich A.; Curbani, Luana; Parker, Timothy A.; Garcia, Jennifer; Schultz, Linda D.; Borges, Endler Marcel

2017-01-01

This experiment describes a simple protocol for teaching acid-base titrations using potentiometry, conductivity, and/or photometry to determine end points without an added indicator. The chosen example examines the titratable acidity of a red wine with NaOH. Wines contain anthocyanins, the colors of which change with pH. Importantly, at the…

Laboratory Activity on Sample Handling and Maintaining a Laboratory Notebook through Simple pH Measurements

ERIC Educational Resources Information Center

Erdmann, Mitzy A.; March, Joe L.

2016-01-01

Sample handling and laboratory notebook maintenance are necessary skills but can seem abstract if not presented to students in context. An introductory exercise focusing on proper sample handling, data collection and laboratory notebook keeping for the general chemistry laboratory was developed to emphasize the importance of keeping an accurate…

Hardness does not affect the physiological responses of wild and domestic strains of diploid and triploid rainbow trout Oncorhynchus mykiss to short-term exposure to pH 9.5.

PubMed

Thompson, W A; Rodela, T M; Richards, J G

2016-08-01

This study examined the effects of water hardness on the physiological responses associated with high pH exposure in multiple strains of diploid and triploid rainbow trout Oncorhynchus mykiss. To accomplish this, three wild strains and one domesticated strain of diploid and triploid O. mykiss were abruptly transferred from control soft water (City of Vancouver dechlorinated tap water; pH 6·7; [CaCO3 ] < 17·9 mg l(-1) ) to control soft water (handling control), high pH soft water (pH 9·5; [CaCO3 ] < 17·9 mg l(-1) ), or high pH hard water (pH 9·5; [CaCO3 ] = 320 mg l(-1) ) followed by sampling at 24 h for physiological measurements. There was a significant effect of ploidy on loss of equilibrium (LOE) over the 24 h exposure, with only triploid O. mykiss losing equilibrium at high pH in both soft and hard water. Furthermore, exposure to pH 9·5 resulted in significant decreases in plasma sodium and chloride, and increases in plasma and brain ammonia with no differences between soft and hard water. There was no significant effect of strain on LOE, but there were significant differences between strains in brain ammonia and plasma cortisol. Overall, there were no clear protective effects of hardness on high pH exposure in these strains of O. mykiss. © 2016 The Fisheries Society of the British Isles.

Process control, energy recovery and cost savings in acetic acid wastewater treatment.

PubMed

Vaiopoulou, E; Melidis, P; Aivasidis, A

2011-02-28

An anaerobic fixed bed loop (AFBL) reactor was applied for treatment of acetic acid (HAc) wastewater. Two pH process control concepts were investigated; auxostatic and chemostatic control. In the auxostatic pH control, feed pump is interrupted when pH falls below a certain pH value in the bioreactor, which results in reactor operation at maximum load. Chemostatic control assures alkaline conditions by setting a certain pH value in the influent, preventing initial reactor acidification. The AFBL reactor treated HAc wastewater at low hydraulic residence time (HRT) (10-12 h), performed at high space time loads (40-45 kg COD/m(3) d) and high space time yield (30-35 kg COD/m(3) d) to achieve high COD (Chemical Oxygen Demand) removal (80%). Material and cost savings were accomplished by utilizing the microbial potential for wastewater neutralization during anaerobic treatment along with application of favourable pH-auxostatic control. NaOH requirement for neutralization was reduced by 75% and HRT was increased up to 20 h. Energy was recovered by applying costless CO(2) contained in the biogas for neutralization of alkaline wastewater. Biogas was enriched in methane by 4 times. This actually brings in more energy profits, since biogas extra heating for CO(2) content during biogas combustion is minimized and usage of other acidifying agents is omitted. Copyright © 2010 Elsevier B.V. All rights reserved.

Solar Powered Remediation and pH Control

DTIC Science & Technology

2017-04-13

Kitanidis, and P.L. McCarty. 2004. Possible factors controlling the effectiveness of bioenhanced dissolution of non -aqueous phase tetrachloroethene...FINAL REPORT Solar Powered Remediation and pH Control ESTCP Project ER-201033 APRIL 2017 David Lippincott, PG CB&I Federal... control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To

Struvite scale formation and control.

PubMed

Parsons, S A; Doyle, J D

2004-01-01

Struvite scale formation is a major operational issue at both conventional and biological nutrient removal wastewater treatment plants. Factors affecting the formation of struvite scales were investigated including supersaturation, pH and pipe material and roughness. A range of control methods have been investigated including low fouling materials, pH control, inhibitor and chemical dosing. Control methods exist to reduce scale formation although each has its advantages and disadvantages.

A simple and efficient method for preparing partially purified phosvitin from egg yolk using ethanol and salts.

PubMed

Ko, K Y; Nam, K C; Jo, C; Lee, E J; Ahn, D U

2011-05-01

The objective of this study was to develop a new protocol that could be used for large-scale separation of phosvitin from egg yolk using ethanol and salts. Yolk granules, which contain phosvitin, were precipitated after diluting egg yolk with 9 volumes of distilled water. The pH of the yolk solution was adjusted to pH 4.0 to 8.0 using 6 N HCl or NaOH, and then yolk granules containing phosvitin was separated by centrifugation at 3,220 × g for 30 min. Lipids and phospholipids were removed from the insoluble yolk granules using 85% ethanol. The optimal volumes and concentration of ethanol in removing lipids from the precipitants were determined. After centrifugation, the lipid-free precipitants were homogenized with 9 volumes of ammonium sulfate [(NH(4))(2)SO(4)] or NaCl to extract phosvitin. The optimal pH and concentration of (NH(4))(2)SO(4) or NaCl for the highest recovery rate and purity for phosvitin in final solution were determined. At pH 6.0, all the phosvitin in diluted egg yolk solution was precipitated. Among the (NH(4))(2)SO(4) and NaCl conditions tested, 10% (NH(4))(2)SO(4) or 10% NaCl at pH 4.0 yielded the greatest phosvitin extraction from the lipid-free precipitants. The recovery rates of phosvitin using (NH(4))(2)SO(4) and NaCl were 72 and 97%, respectively, and their purity was approximately 85%. Salt was removed from the extract using ultrafiltration. The salt-free phosvitin solution was concentrated using ultrafiltration, the impurities were removed by centrifugation, and the resulting solution was freeze-dried. The partially purified phosvitin was suitable for human use because ethanol was the only solvent used to remove lipids, (NH(4))(2)SO(4) or NaCl was used to extract phosvitin, and ultrafiltration was used to remove salt and concentrate the extract. The developed method was simple and suitable for a large-scale preparation of partially purified phosvitin.

Decreased Brain pH as a Shared Endophenotype of Psychiatric Disorders

PubMed Central

Hagihara, Hideo; Catts, Vibeke S; Katayama, Yuta; Shoji, Hirotaka; Takagi, Tsuyoshi; Huang, Freesia L; Nakao, Akito; Mori, Yasuo; Huang, Kuo-Ping; Ishii, Shunsuke; Graef, Isabella A; Nakayama, Keiichi I; Shannon Weickert, Cynthia; Miyakawa, Tsuyoshi

2018-01-01

Although the brains of patients with schizophrenia and bipolar disorder exhibit decreased brain pH relative to those of healthy controls upon postmortem examination, it remains controversial whether this finding reflects a primary feature of the diseases or is a result of confounding factors such as medication and agonal state. To date, systematic investigation of brain pH has not been undertaken using animal models that can be studied without confounds inherent in human studies. In the present study, we first reevaluated the pH of the postmortem brains of patients with schizophrenia and bipolar disorder by conducting a meta-analysis of existing data sets from 10 studies. We then measured pH, lactate levels, and related metabolite levels in brain homogenates from five neurodevelopmental mouse models of psychiatric disorders, including schizophrenia, bipolar disorder, and autism spectrum disorder. All mice were drug naive with the same agonal state, postmortem interval, and age within each strain. Our meta-analysis revealed that brain pH was significantly lower in patients with schizophrenia and bipolar disorder than in control participants, even when a few potential confounding factors (postmortem interval, age, and history of antipsychotic use) were considered. In animal experiments, we observed significantly lower pH and higher lactate levels in the brains of model mice relative to controls, as well as a significant negative correlation between pH and lactate levels. Our findings suggest that lower pH associated with increased lactate levels is not a mere artifact, but rather implicated in the underlying pathophysiology of schizophrenia and bipolar disorder. PMID:28776581

A low pH does not determine the community dynamics of spontaneously developed backslopped liquid wheat sourdoughs but does influence their metabolite kinetics.

PubMed

Van Kerrebroeck, Simon; Bastos, Francisca Casanova C; Harth, Henning; De Vuyst, Luc

2016-12-19

This study dealt with the influence of a crucial pH value of 4.0 on the microbiota of spontaneously fermented backslopped liquid wheat sourdoughs. Two spontaneously fermented wheat sourdough fermentation experiments were carried out, one without control of the pH and one with the pH kept constant at pH4.0, both during nine backslopping steps. In each case, two additional backslopping steps were carried out, with the pH kept constant at 4.0 and with free pH, respectively. Keeping the pH constant at 4.0 changed the microbial community dynamics and metabolite kinetics of the sourdough fermentations. A slower prevalence of sourdough-specific Kazachstania yeasts occurred. Nevertheless, in both experiments, Lactobacillus fermentum, Lb. plantarum/pentosus/paraplantarum, and Kazachstania exigua/bulderi/barnettii prevailed ultimately. The lactic acid and ethanol concentration profiles were affected positively by keeping the pH constant at a minimum of 4.0 as well as the l- and d-lactic acid ratio profile, a potential biological marker for sourdough stability and maturity. Also, the concentration and diversity of acetate esters and their precursors, in particular isoamyl acetate and isoamyl alcohol, were affected negatively by the pH control, indicating the role of pH stress in the sourdough aroma formation. Copyright © 2016 Elsevier B.V. All rights reserved.

Atmospheric Processing of Volcanic Glass: Effects on Iron Solubility and Redox Speciation.

PubMed

Maters, Elena C; Delmelle, Pierre; Bonneville, Steeve

2016-05-17

Volcanic ash from explosive eruptions can provide iron (Fe) to oceanic regions where this micronutrient limits primary production. Controls on the soluble Fe fraction in ash remain poorly understood but Fe solubility is likely influenced during atmospheric transport by condensation-evaporation cycles which induce large pH fluctuations. Using glass powder as surrogate for ash, we experimentally simulate its atmospheric processing via cycles of pH 2 and 5 exposure. Glass fractional Fe solubility (maximum 0.4%) is governed by the pH 2 exposure duration rather than by the pH fluctuations, however; pH 5 exposure induces precipitation of Fe-bearing nanoparticles which (re)dissolve at pH 2. Glass leaching/dissolution release Fe(II) and Fe(III) which are differentially affected by changes in pH; the average dissolved Fe(II)/Fetot ratio is ∼0.09 at pH 2 versus ∼0.18 at pH 5. Iron release at pH 2 from glass with a relatively high bulk Fe(II)/Fetot ratio (0.5), limited aqueous Fe(II) oxidation at pH 5, and possibly glass-mediated aqueous Fe(III) reduction may render atmospherically processed ash a significant source of Fe(II) for phytoplankton. By providing new insight into the form(s) of Fe associated with ash as wet aerosol versus cloud droplet, we improve knowledge of atmospheric controls on volcanogenic Fe delivery to the ocean.

Toxin studies using an integrated biophysical and structural biology approach.

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

Last, Julie A.; Schroeder, Anne E.; Slade, Andrea Lynn

2005-03-01

Clostridial neurotoxins, such as botulinum and tetanus, are generally thought to invade neural cells through a process of high affinity binding mediated by gangliosides, internalization via endosome formation, and subsequent membrane penetration of the catalytic domain activated by a pH drop in the endosome. This surface recognition and internalization process is still not well understood with regard to what specific membrane features the toxins target, the intermolecular interactions between bound toxins, and the molecular conformational changes that occur as a result of pH lowering. In an effort to elucidate the mechanism of tetanus toxin binding and permeation through the membranemore » a simple yet representative model was developed that consisted of the ganglioside G{sub tlb} incorporated in a bilayer of cholesterol and DPPC (dipalmitoylphosphatidyl choline). The bilayers were stable over time yet sensitive towards the binding and activity of whole toxin. A liposome leakage study at constant pH as well as with a pH gradient, to mimic the processes of the endosome, was used to elucidate the effect of pH on the toxin's membrane binding and permeation capability. Topographic imaging of the membrane surface, via in situ tapping mode AFM, provided nanoscale characterization of the toxin's binding location and pore formation activity.« less

Design and fabrication of spectrally selective emitter for thermophotovoltaic system by using nano-imprint lithography

NASA Astrophysics Data System (ADS)

Kim, Jong-Moo; Park, Keum-Hwan; Kim, Da-Som; Hwang, Bo-yeon; Kim, Sun-Kyung; Chae, Hee-Man; Ju, Byeong-Kwon; Kim, Young-Seok

2018-01-01

Thermophotovoltaic (TPV) systems have attracted attention as promising power generation systems that can directly convert the radiant energy produced by the combustion of fuel into electrical energy. However, there is a fundamental limit of their conversion efficiency due to the broadband distribution of the radiant spectrum. To overcome this problem, several spectrally selective thermal emitter technologies have been investigated, including the fabrication of photonic crystal (PhC) structures. In this paper, we present some design rules based on finite-a difference time-domain (FDTD) simulation results for tungsten (W) PhC emitter. The W 2D PhC was fabricated by a simple nano-imprint lithography (NIL) process, and inductive coupled plasma reactive ion etching (ICP-RIE) with an isotropic etching process, the benefits and parameters of which are presented. The fabricated W PhC emitter showed spectrally selective emission near the infrared wavelength range, and the optical properties varied depending on the size of the nano-patterns. The measured results of the fabricated prototype structure correspond well to the simulated values. Finally, compared with the performance of a flat W emitter, the total thermal emitter efficiency was almost 3.25 times better with the 2D W PhC structure.

Molecular adsorption at electrolyte/α-Al2O3 interface of aluminum electrolytic capacitor revealed by sum frequency vibrational spectroscopy.

PubMed

Jia, Ming; Hu, Xiaoyu; Liu, Jin; Liu, Yexiang; Ai, Liang

2017-05-21

The operating voltage of an aluminum electrolytic capacitor is determined by the breakdown voltage (U b ) of the Al 2 O 3 anode. U b is related to the molecular adsorption at the Al 2 O 3 /electrolyte interface. Therefore, we have employed sum-frequency vibrational spectroscopy (SFVS) to study the adsorption states of a simple electrolyte, ethylene glycol (EG) solution with ammonium adipate, on an α-Al 2 O 3 surface. In an acidic electrolyte (pH < 6), the Al 2 O 3 surface is positively charged. The observed SFVS spectra show that long chain molecules poly ethylene glycol and ethylene glycol adipate adopt a "lying" orientation at the interface. In an alkaline electrolyte (pH > 8), the Al 2 O 3 surface is negatively charged and the short chain EG molecules adopt a "tilting" orientation. The U b results exhibit a much higher value at pH < 6 compared with that at pH > 8. Since the "lying" long chain molecules cover and protect the Al 2 O 3 surface, U b increases with a decrease of pH. These findings provide new insights to study the breakdown mechanisms and to develop new electrolytes for high operating voltage capacitors.

Synthesis of Spongy-Like Mesoporous Hydroxyapatite from Raw Waste Eggshells for Enhanced Dissolution of Ibuprofen Loaded via Supercritical CO2

PubMed Central

Ibrahim, Abdul-Rauf; Li, Xiangyun; Zhou, Yulan; Huang, Yan; Chen, Wenwen; Wang, Hongtao; Li, Jun

2015-01-01

The use of cheaper and recyclable biomaterials (like eggshells) to synthesize high purity hydroxyapatite (HAp) with better properties (small particle size, large surface area and pore volume) for applications (in environmental remediation, bone augmentation and replacement, and drug delivery systems) is vital since high-purity synthetic calcium sources are expensive. In this work, pure and mesoporous HAp nanopowder with large pore volume (1.4 cm3/g) and surface area (284.1 m2/g) was produced from raw eggshells at room temperature using a simple two-step procedure. The control of precursor droplets could stabilize the pH value of the reaction solution, because of the size of the needle (of the syringe pump used for precursor additions) leading to production of HAp with high surface area and pore size. The as-produced HAp revealed high ibuprofen (as a model drug) loading (1.38 g/g HAp), enhanced dissolution and controllable release of the drug via solute-saturated supercritical carbon dioxide. PMID:25860950

Stimulus-responsive zinc oxide-functionalized macromolecular humic acid nanocarrier for enhancement of antibacterial activity of ciprofloxacin hydrochloride.

PubMed

Murugesan, Gowri; Latha, Nachimuthu; Suganya, Kannan; Murugan, Marudhamuthu; Munusamy, Murugan A; Rajan, Mariappan

2018-07-15

Macromolecular of naturally occurring humic acid (HA) have garnered interest in the chemical, biological and medicine industry owing to their unique behavior, i.e., strong adsorptive and non-toxic nature. Here, we investigated the functionalization of organic (HA) with inorganic (ZnO) hybrid nanoparticles for topical and site-targeted delivery of ciprofloxacin by simple emulsification techniques. Ciprofloxacin (CIPRO)-encapsulated hybrid nanocarrier constitute an attractive novel drug delivery vehicle for sustained release of antibiotics to bacterial infection sites in an extended and controlled manner. The analytical characteristics of the designed system were thoroughly investigated by FTIR, XRD, SEM/EDAX, and TEM. The drug release of ciprofloxacin over 24h was 87.5%, 98.03%, 97.44%, and 97.24% for pH2.5, 5.5, 6.8, and 8.0, respectively. The antibacterial activities results confirmed that the CIPRO-encapsulated hybrid nanocarrier showed excellent growth inhibition against microorganisms. This hybrid nanocarrier loaded with antibiotics represents a promising approach for targeted and controlled drug delivery to infected sites. Copyright © 2018 Elsevier B.V. All rights reserved.

Controlled synthesis of flexible graphene aerogels macroscopic monolith as versatile agents for wastewater treatment

NASA Astrophysics Data System (ADS)

Dong, Shuying; Xia, Longji; Guo, Teng; Zhang, Fangyuan; Cui, Lingfang; Su, Xianfa; Wang, Dong; Guo, Wei; Sun, Jianhui

2018-07-01

Emerging applications for environmental purification require agents that not only possess high decontamination efficiency, but also are capable of withstanding mechanical deformation without secondary pollution and degradation of performance. To this end, we have controlled synthesis of mechanically flexible graphene aerogel (GA) by vacuum freeze-drying of their hydrogel precursors obtained from heating the aqueous mixtures of graphene oxide (GO) and Vitamin C (VC) without stirring. Through the adaptable process conditions, such as the particle size of carbon, GO concentration, dosage of reducing agent and solution pH, the highly porous, ultralight and mechanically flexible GA are synthesized. Owing to the porous, robust and stable structure, the resulting GA show very promising performance in water purification including enrichment of organic liquid solvents (alcohols, oil and alkanes), removal of hexavalent chromium Cr(VI) and purified industrial wastewater, as well as flexible conductors. The successful creation of the GA may provide new insights into the design of carbon-based aerogels for various applications, as the GA can be prepared via a very simple procedure and available in macroscopic diverse morphologies with tunable porosity.

Kinetics and modeling of hexavalent chromium reduction in Enterobacter cloacae

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

Yamamoto, Koji; Kato, Junichi; Yano, Takuo

1993-01-05

Kinetics of bacterial reduction of toxic hexavalent chromium (chromate: CrO[sub 4][sup [minus]2]) was investigated using batch and fed-batch cultures of Enterobacter cloacae strain HO1. In fed-batch cultures, the CrO[sub 4][sup [minus]2] feed was controlled on the basis of the rate of pH change. This control strategy has proven to be useful for avoiding toxic CrO[sub 3][sup [minus]2] overload. A simple mathematical model was developed to describe the bacterial process of CrO[sub 4][sup [minus]2] reduction. In this model, two types of bacterial cells were considered: induced, CrO[sub 4][sup [minus]2]-resistant cells and uninduced, sensitive ones. Only resistant cells were assumed to bemore » able to reduce CrO[sub 4][sup [minus]2]. These fundamental ideas were supported by the model predictions which well approximated all experimental data. In a simulation study, the model was also used to optimize fed-batch cultures, instead of lengthy and expensive laboratory experiments.« less

Oxygen Consumption by Red Wines. Part I: Consumption Rates, Relationship with Chemical Composition, and Role of SO₂.

PubMed

Ferreira, Vicente; Carrascon, Vanesa; Bueno, Mónica; Ugliano, Maurizio; Fernandez-Zurbano, Purificación

2015-12-30

Fifteen Spanish red wines extensively characterized in terms of SO2, color, antioxidant indexes, metals, and polyphenols were subjected to five consecutive sensor-controlled cycles of air saturation at 25 °C. Within each cycle, O2 consumption rates cannot be interpreted by simple kinetic models. Plots of cumulated consumed O2 made it possible to define a fast and highly wine-dependent initial O2 consumption rate and a second and less variable average O2 consumption rate which remains constant in saturations 2 to 5. Both rates have been satisfactorily modeled, and in both cases they were independent of Fe and SO2 and highly dependent on Cu levels. Average rates were also related to Mn, pH, Folin, protein precipitable proanthocyanidins (PPAs), and polyphenolic profile. Initial rates were strong and negatively correlated to SO2 consumption, indicating that such an initial rate is either controlled by an unknown antioxidant present in some wines or affected by a poor real availability of SO2. Remaining unreacted SO2 is proportional to initial combined SO2 and to final free acetaldehyde.

Magnetic Resonance Imaging-Guided Multi-Drug Chemotherapy and Photothermal Synergistic Therapy with pH and NIR-Stimulation Release.

PubMed

Yang, Ji-Chun; Chen, Yang; Li, Yu-Hao; Yin, Xue-Bo

2017-07-12

The combination of multidrug chemotherapy and photothermal therapy (PTT) enhances cancer therapeutic efficacy. Herein, we develop a simple and smart pH/NIR dual-stimulus-responsive degradable mesoporous CoFe 2 O 4 @PDA@ZIF-8 sandwich nanocomposite. The mesoporous CoFe 2 O 4 core acts as T 2 -weighted magnetic resonance (MR) imaging probe, PTT agent, and loading platform of hydrophilic doxorubicin (DOX). A polydopamine (PDA) layer is used to avoid the premature leakage of DOX before arriving at tumor site, enhance PTT efficiency, and facilitate the integration of ZIF-8 (a kind of metal-organic framework). The ZIF-8 shell serves to encapsulate hydrophobic camptothecin (CPT) and as the switch for the pH and NIR stimulation-responsive release of the two drugs. Therefore, T 2 -weighted MR imaging-guided multidrug chemotherapy and PTT synergistic treatment is achieved. Two kinds of anticancer drugs, hydrophilic DOX and hydrophobic CPT, are successfully loaded in CoFe 2 O 4 and ZIF-8, respectively, so no mutual interference between the two drugs exists. A unique two-stage stepwise release process is exhibited for CPT and DOX with an interval of 12 h to improve the anticancer efficacy under the acidic microenvironment of tumor tissue. NIR irradiation achieves the burst drug-release and PTT after laser stimulation, simultaneously. With this smart design, high drug concentration is achieved at the tumor site by quick release, especially for the therapeutic drugs that show nonlinear pharmacokinetics, and PTT is integrated efficiently. Furthermore, negligible biotoxicity and a remarkable synergic antitumor effect of the hybrid nanocomposites are validated by HepG2 cells and tumor-bearing mice as models. Our multidrug delivery-releasing composite improves tumor therapeutic efficiency significantly compared with a single-drug chemotherapy system. The simple multifunctional composite system can be applied as an effective platform for personal nanomedicine with diagnosis, smart drug delivery, and cancer treatment through its remarkable photothermal property and controllable multidrug release.

Prophylactic transcervical amnioinfusion in laboring women with oligohydramnios.

PubMed

Amin, A F; Mohammed, M S; Sayed, G H; Abdel-Razik, S

2003-05-01

Evaluation of prophylactic intrapartum amnioinfusion in women with oligohydramnios. Assiut University Hospital during the period from February 2000 to September 2001, 160 laboring women with oligohydramnios [amniotic fluid index (AFI)

Rapid, room-temperature synthesis of amorphous selenium/protein composites using Capsicum annuum L extract

NASA Astrophysics Data System (ADS)

Li, Shikuo; Shen, Yuhua; Xie, Anjian; Yu, Xuerong; Zhang, Xiuzhen; Yang, Liangbao; Li, Chuanhao

2007-10-01

We describe the formation of amorphous selenium (α-Se)/protein composites using Capsicum annuum L extract to reduce selenium ions (SeO32-) at room temperature. The reaction occurs rapidly and the process is simple and easy to handle. A protein with a molecular weight of 30 kDa extracted from Capsicum annuum L not only reduces the SeO32- ions to Se0, but also controls the nucleation and growth of Se0, and even participates in the formation of α-Se/protein composites. The size and shell thickness of the α-Se/protein composites increases with high Capsicum annuum L extract concentration, and decreases with low reaction solution pH. The results suggest that this eco-friendly, biogenic synthesis strategy could be widely used for preparing inorganic/organic biocomposites. In addition, we also discuss the possible mechanism of the reduction of SeO32- ions by Capsicum annuum L extract.

Decolorization of turbid sugar juice from sugar factory using waste powdered carbon

NASA Astrophysics Data System (ADS)

Aljohani, Hind; Ahmed, Youssef; El-Shafey, Ola; El-Shafey, Shaymaa; Fouad, Rasha; Shoueir, Kamel

2018-03-01

Waste management of powdered activated carbon from cyclone of some sugar factories was used for decolorization of sugar mud juice (SMJ) in this study. The presence of powdered activated carbon waste (PACW) was admitted again for their use in SMJ decolorization. The determined specific surface area are typically S BET = 613.887 m2/g and the pore distribution lies in mesoporous domain. Color removal (CR%) and decolorization capacity (DC) of the characterized PACW are similar to those of decolorants used at this time for sugar refining. The CR% with PACW reached 81.03% at pH7.0 and dosed in the amount 0.5 g/50 ml of SMJ. There are two acceptable mechanisms illustrates the attachments between phenols and carboxylate ions. In this paper, we put a simple and rapid dark liquid decolorization by controlling rejected carbon waste, which will be useful for treatment of dark liquid sugar.

Bioactive and Porous Metal Coatings for Improved Tissue Regeneration

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

Campbell, A. A.

Our first objective was to develop the SIM process for the deposition of calcium phosphate films. This process is based on the observation that, in nature, living organisms use macromolecules to control the nucleation and growth of mineral phases. These macromolecules act as templates where various charged functional groups, contained within the molecule, can interact with the ions in the surrounding media, thus stimulating crystal nucleation and growth. Rather than using complex proteins or biopolymers, surface modification schemes were developed to place simple functional groups on the underlying substrate using self-assembling monolayers. Once the substrate was chemically modified, it wasmore » then placed into an aqueous solution containing soluble precursors of the desired mineral coating. Solution pH, ionic concentration and temperature is maintained in a regime where the solution is supersaturated with respect to the desired mineral phase, thereby creating the driving force for nucleation and growth.« less

Application of chemometric analysis based on physicochemical and chromatographic data for the differentiation origin of plant protection products containing chlorpyrifos.

PubMed

Miszczyk, Marek; Płonka, Marlena; Bober, Katarzyna; Dołowy, Małgorzata; Pyka, Alina; Pszczolińska, Klaudia

2015-01-01

The aim of this study was to investigate the similarities and dissimilarities between the pesticide samples in form of emulsifiable concentrates (EC) formulation containing chlorpyrifos as active ingredient coming from different sources (i.e., shops and wholesales) and also belonging to various series. The results obtained by the Headspace Gas Chromatography-Mass Spectrometry method and also some selected physicochemical properties of examined pesticides including pH, density, stability, active ingredient and water content in pesticides tested were compared using two chemometric methods. Applicability of simple cluster analysis and also principal component analysis of obtained data in differentiation of examined plant protection products coming from different sources was confirmed. It would be advantageous in the routine control of originality and also in the detection of counterfeit pesticides, respectively, among commercially available pesticides containing chlorpyrifos as an active ingredient.

Photometric method for determination of acidity constants through integral spectra analysis

NASA Astrophysics Data System (ADS)

Zevatskiy, Yuriy Eduardovich; Ruzanov, Daniil Olegovich; Samoylov, Denis Vladimirovich

2015-04-01

An express method for determination of acidity constants of organic acids, based on the analysis of the integral transmittance vs. pH dependence is developed. The integral value is registered as a photocurrent of photometric device simultaneously with potentiometric titration. The proposed method allows to obtain pKa using only simple and low-cost instrumentation. The optical part of the experimental setup has been optimized through the exclusion of the monochromator device. Thus it only takes 10-15 min to obtain one pKa value with the absolute error of less than 0.15 pH units. Application limitations and reliability of the method have been tested for a series of organic acids of various nature.

Amphiphilic polymeric micelle as pseudostationary phase in electrokinetic chromatography for analysis of eight corticosteroids in cosmetics.

PubMed

Xu, Xiaojin; Ni, Xinjiong; Cao, Yuhua; Zhuo, Xiaolu; Yang, Xiaoxiao; Cao, Guangqun

2014-03-01

Amphiphilic polymeric micelle, as a novel pseudostationary phase in EKC was used to determine eight kinds of corticosteroids namely hydrocortisone, prednisolone, hydrocortisone acetate, prednisone, cortisone acetate, prednisolone acetate, dexamethasone, and triamcinolone acetonide in cosmetics. Amphiphilic random copolymer poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) was micellizated via neutralization in alkaline aqueous solution. The influences of the molar ratio of monomer MMA to MAA, the concentration of polymer and pH on the polymeric micelle microstructure and EKC performances were investigated. As molar ratio of MMA to MAA in P(MMA-co-MAA) increased, both CMC and environmental polarity of the inner core in polymeric micelle decreased dramatically. With increasing monomer ratio, the size of polymeric micelles increased firstly, and then decreased, finally increased again. ζ potential of the micelle had a slight decline trend. As increment of polymer concentration, the size of the polymeric micelle increased steadily. By optimizing the monomer ratio, the polymer concentration, and pH of the running buffer, as well as operation conditions such as separation voltage and temperature, the eight analytes could be separated within 16.5 min using 7.5 mg/mL polymer with the monomer ratio of 7:3 dissolved in pH 9.2 borax buffer as the running buffer. The method has been used for analysis of corticosteroids in cosmetic samples with simple extraction; the recoveries for eight analytes were between 85.9 and 106%. This method was of accuracy, repeatability, pretreatment simplicity, and could be applied to the quality control of cosmetics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mapping of a Novel Race Specific Resistance Gene to Phytophthora Root Rot of Pepper (Capsicum annuum) Using Bulked Segregant Analysis Combined with Specific Length Amplified Fragment Sequencing Strategy.

PubMed

Xu, Xiaomei; Chao, Juan; Cheng, Xueli; Wang, Rui; Sun, Baojuan; Wang, Hengming; Luo, Shaobo; Xu, Xiaowan; Wu, Tingquan; Li, Ying

2016-01-01

Phytophthora root rot caused by Phytophthora capsici (P. capsici) is a serious limitation to pepper production in Southern China, with high temperature and humidity. Mapping PRR resistance genes can provide linked DNA markers for breeding PRR resistant varieties by molecular marker-assisted selection (MAS). Two BC1 populations and an F2 population derived from a cross between P. capsici-resistant accession, Criollo de Morelos 334 (CM334) and P. capsici-susceptible accession, New Mexico Capsicum Accession 10399 (NMCA10399) were used to investigate the genetic characteristics of PRR resistance. PRR resistance to isolate Byl4 (race 3) was controlled by a single dominant gene, PhR10, that was mapped to an interval of 16.39Mb at the end of the long arm of chromosome 10. Integration of bulked segregant analysis (BSA) and Specific Length Amplified Fragment sequencing (SLAF-seq) provided an efficient genetic mapping strategy. Ten polymorphic Simple Sequence Repeat (SSR) markers were found within this region and used to screen the genotypes of 636 BC1 plants, delimiting PhR10 to a 2.57 Mb interval between markers P52-11-21 (1.5 cM away) and P52-11-41 (1.1 cM). A total of 163 genes were annotated within this region and 31 were predicted to be associated with disease resistance. PhR10 is a novel race specific gene for PRR, and this paper describes linked SSR markers suitable for marker-assisted selection of PRR resistant varieties, also laying a foundation for cloning the resistance gene.

Modelling the leaching of Pb, Cd, As, and Cr from cementitious waste using PHREEQC.

PubMed

Halim, Cheryl E; Short, Stephen A; Scott, Jason A; Amal, Rose; Low, Gary

2005-10-17

A leaching model was developed using the United States Geological Survey public domain PHREEQC geochemical package to simulate the leaching of Pb, Cd, As, and Cr from cementitious wastes. The model utilises both kinetic terms and equilibrium thermodynamics of key compounds and provides information on leachate and precipitate speciation. The model was able to predict the leaching of Pb, Cd, As, and Cr from cement in the presence of both simple (0.1 and 0.6M acetic acid) and complex municipal landfill leachates. Heavy metal complexation by the municipal landfill leachate was accounted for by the introduction of a monoprotic organic species into the model. The model indicated Pb and As were predominantly incorporated within the calcium silicate hydrate matrix while a greater portion of Cd was seen to exist as discrete particles in the cement pores and Cr (VI) existed mostly as free CrO4(2-) ions. Precipitation was found to be the dominant mechanism controlling heavy metal solubility with carbonate and silicate species governing the solubility of Pb and carbonate, silicate and hydroxide species governing the solubility of Cd. In the presence of acetic acid, at low pH values Pb and Cd acetate complexes were predominant whereas, at high pH values, hydroxide species dominated. At high pH values, the concentration of As in the leachate was governed by the solubility of Ca3(AsO4)2 with the presence of carbonate alkalinity competing with arsenate for Ca ions. In the presence of municipal landfill leachate, Pb and Cd organic complexes dominated the heavy metal species in solution. The reduction of As and Cr in municipal landfill leachate was crucial for determining aqueous speciation, with typical municipal landfill conditions providing the reduced forms of As and Cr.

Synthesis of hydroxyapatite nanorods for application in water defluoridation and optimization of process variables: Advantage of ultrasonication with precipitation method over conventional method.

PubMed

Mehta, Dhiraj; Mondal, Poonam; Saharan, Virendra Kumar; George, Suja

2017-07-01

This research work presents the synthesis of hydroxyapatite (Hap) nanorods for defluoridation of drinking water by using both conventional (CM) and ultrasonication with precipitation (USPM) methods. Calcium nitrate was reacted with potassium phosphate in presence of ammonia for controlled pH to synthesize Hap nanorods, which was characterized using FTIR, XRD, SEM, TG-DTA, and TEM/EDS for determining its phase composition, structural and thermal decomposition behavior. When USPM method was used for synthesis, the yield of the Hap nanorods was improved from 83.24±1.0% to 90.2±1.0%, and complete phase transformation occurred with formation of elongated Hap nanorods. Effects of process parameters such as solution pH, contact time and adsorbent dose were studied through response surface methodology (RSM). A simple quadratic model was developed using Central Composite Design (CCD) and optimum parameters for fluoride adsorption process were determined to be pH 7, contact time 3h and adsorbent dose 7g/L for maximum removal capacity. Fluoride removal efficiency was predicted to be 93.64% which was very close to the experimental value obtained at 92.86% using ultrasonically prepared Hap. Fluoride adsorption isotherms fitted the Freundlich isotherm with an adsorption capacity of 1.49mg/g, while the kinetic studies revealed that the process followed pseudo-second order model. The treated water quality parameters such as residual fluoride, calcium leached, total hardness and alkalinity was investigated, and it was observed that all these parameters were within the permissible limits as per WHO and BIS standards. Copyright © 2017 Elsevier B.V. All rights reserved.

Recombinant human hyaluronidase PH20 (rHuPH20) facilitates subcutaneous infusions of large volumes of immunoglobulin in a swine model.

PubMed

Kang, David W; Jadin, Laurence; Nekoroski, Tara; Drake, Fred H; Zepeda, Monica L

2012-08-01

Many patients with primary immunodeficiency disease (PIDD) require lifelong immunoglobulin (Ig) replacement therapy. Home-based subcutaneous (SC) infusion provides advantages to patients with PIDD compared to hospital-based intravenous infusion. One limitation of current practice with SCIg infusion is the need for small-volume infusions at multiple injection sites on a frequent basis. A method was developed for large-volume SC infusion that uses preinfusion of recombinant human hyaluronidase (rHuPH20) to facilitate fluid dispersion. Miniature swine was used as a preclinical model to assess the effects of rHuPH20-facilitated infusions, of a single monthly dose, on fluid dispersion, infusion-related pressure, swelling, induration, and tissue damage. Preinfusion of vehicle (control) or rHuPH20 (75 U/g Ig) was performed simultaneously on contralateral abdominal sites on each animal, followed by infusion of 300 mL 10 % Ig (30 g) at each site. Compared to control infusions, rHuPH20 significantly reduced infusion pressure and induration (p < 0.05) and accelerated postinfusion Ig dispersion. Histological evaluation of infusion site tissue showed moderate to severe swelling for the control. Swelling after rHuPH20-facilitated infusion was mild on day 1 and had completely resolved shortly thereafter. Laser Doppler imaging of control infusion sites revealed local cutaneous hypoperfusion during Ig infusion, which was reduced almost 7-fold (p < 0.05) with the use of rHuPH20. These results demonstrate that rHuPH20-facilitated Ig infusion is associated with improved dispersion of Ig, resulting in reduced tissue pressure, induration, and reduced risk of tissue damage from mechanical trauma or local ischemia, thus enabling SC administration of large volumes of Ig at a single site.

Maltodextrin based proniosomes of nateglinide: bioavailability assessment.

PubMed

Sahoo, Ranjan Ku; Biswas, Nikhil; Guha, Arijit; Kuotsu, Ketousetuo

2014-08-01

The present study delineates the fabrication of maltodextrin based proniosomes of nateglinide and their potential as controlled delivery system for diabetic therapy. New Zealand albino male rabbits have been used as animal model for in vivo study. To evaluate the bioavailability of nateglinide proniosome, a rapid, simple and sensitive HPLC method with photodiode array detection was developed and validated to determine nateglinide in rabbit plasma. Chromatographic separation was achieved by a reverse phase C18 column using a mixture of acetonitrile:methanol:10mM phosphate buffer (pH 3.5) in the ratio of 56:14:30 (%v/v) as the mobile phase at a flow rate of 1.0ml/min and quantified based on drug/IS peak area ratios. Gliclazide was used as the internal standard. The intra- and inter-day relative standard deviations of four tested concentrations were below 2%. The nateglinide proniosome formulation exhibited significantly higher plasma concentration than those of pure drug. The study revealed that the rate and extent of absorption of nateglinide from the proniosomal formulation was comparatively enhanced that of pure drug. Maltodextrin based proniosomes of nateglinide is not only simple and cost efficient delivery but also offers a useful and promising carrier for diabetic therapy through oral administration. Copyright © 2014 Elsevier B.V. All rights reserved.

Controlling self-assembly of diphenylalanine peptides at high pH using heterocyclic capping groups.

PubMed

Martin, Adam D; Wojciechowski, Jonathan P; Robinson, Andrew B; Heu, Celine; Garvey, Christopher J; Ratcliffe, Julian; Waddington, Lynne J; Gardiner, James; Thordarson, Pall

2017-03-08

Using small angle neutron scattering (SANS), it is shown that the existence of pre-assembled structures at high pH for a capped diphenylalanine hydrogel is controlled by the selection of N-terminal heterocyclic capping group, namely indole or carbazole. At high pH, changing from a somewhat hydrophilic indole capping group to a more hydrophobic carbazole capping group results in a shift from a high proportion of monomers to self-assembled fibers or wormlike micelles. The presence of these different self-assembled structures at high pH is confirmed through NMR and circular dichroism spectroscopy, scanning probe microscopy and cryogenic transmission electron microscopy.

Revisiting the pH Effect on Orthophosphate Control of Plumbosolvency

EPA Science Inventory

Although solubility models for Pb(II) have largely been successful for giving corrosion control treatment guidance for over 2 decades, very little systematic research has been done to precisely define plumbosolvency responses to changes in pH, carbonate and phosphate concentratio...

Evaluation of recently validated non-invasive formula using basic lung functions as new screening tool for pulmonary hypertension in idiopathic pulmonary fibrosis patients

PubMed Central

Ghanem, Maha K.; Makhlouf, Hoda A.; Agmy, Gamal R.; Imam, Hisham M. K.; Fouad, Doaa A.

2009-01-01

BACKGROUND: A prediction formula for mean pulmonary artery pressure (MPAP) using standard lung function measurement has been recently validated to screen for pulmonary hypertension (PH) in idiopathic pulmonary fibrosis (IPF) patients. OBJECTIVE: To test the usefulness of this formula as a new non invasive screening tool for PH in IPF patients. Also, to study its correlation with patients' clinical data, pulmonary function tests, arterial blood gases (ABGs) and other commonly used screening methods for PH including electrocardiogram (ECG), chest X ray (CXR), trans-thoracic echocardiography (TTE) and computerized tomography pulmonary angiography (CTPA). MATERIALS AND METHODS: Cross-sectional study of 37 IPF patients from tertiary hospital. The accuracy of MPAP estimation was assessed by examining the correlation between the predicted MPAP using the formula and PH diagnosed by other screening tools and patients' clinical signs of PH. RESULTS: There was no statistically significant difference in the prediction of PH using cut off point of 21 or 25 mm Hg (P = 0.24). The formula-predicted MPAP greater than 25 mm Hg strongly correlated in the expected direction with O2 saturation (r = −0.95, P < 0.000), partial arterial O2 tension (r = −0.71, P < 0.000), right ventricular systolic pressure measured by TTE (r = 0.6, P < 0.000) and hilar width on CXR (r = 0.31, P = 0.03). Chest symptoms, ECG and CTPA signs of PH poorly correlated with the same formula (P > 0.05). CONCLUSIONS: The prediction formula for MPAP using standard lung function measurements is a simple non invasive tool that can be used as TTE to screen for PH in IPF patients and select those who need right heart catheterization. PMID:19881164

An Optical Sensor with Polyaniline-Gold Hybrid Nanostructures for Monitoring pH in Saliva.

PubMed

Luo, Chongdai; Wang, Yangyang; Li, Xuemeng; Jiang, Xueqin; Gao, Panpan; Sun, Kang; Zhou, Jianhua; Zhang, Zhiguang; Jiang, Qing

2017-03-17

Saliva contains important personal physiological information that is related to some diseases, and it is a valuable source of biochemical information that can be collected rapidly, frequently, and without stress. In this article, we reported a new and simple localized surface plasmon resonance (LSPR) substrate composed of polyaniline (PANI)-gold hybrid nanostructures as an optical sensor for monitoring the pH of saliva samples. The overall appearance and topography of the substrates, the composition, and the wettability of the LSPR surfaces were characterized by optical and scanning electron microscope (SEM) images, infrared spectra, and contact angles measurement, respectively. The PANI-gold hybrid substrate readily responded to the pH. The response time was very short, which was 3.5 s when the pH switched from 2 to 7, and 4.5 s from 7 to 2. The changes of visible-near-infrared (NIR) spectra of this sensor upon varying pH in solution showed that-for the absorption at given wavelengths of 665 nm and 785 nm-the sensitivities were 0.0299 a.u./pH (a.u. = arbitrary unit) with a linear range of pH = 5-8 and 0.0234 a.u./pH with linear range of pH = 2-8, respectively. By using this new sensor, the pH of a real saliva sample was monitored and was consistent with the parallel measurements with a standard laboratory method. The results suggest that this novel LSPR sensor shows great potential in the field of mobile healthcare and home medical devices, and could also be modified by different sensitive materials to detect various molecules or ions in the future.

Pituitary hyperplasia: case series and literature review of an under-recognised and heterogeneous condition

PubMed Central

Earls, Peter; McCormack, Ann I

2015-01-01

Summary Pituitary hyperplasia (PH) occurs in heterogeneous settings and remains under-recognised. Increased awareness of this condition and its natural history should circumvent unnecessary trans-sphenoidal surgery. We performed an observational case series of patients referred to a single endocrinologist over a 3-year period. Four young women were identified with PH manifesting as diffuse, symmetrical pituitary enlargement near or touching the optic apparatus on MRI. The first woman presented with primary hypothyroidism and likely had thyrotroph hyperplasia given prompt resolution with thyroxine. The second and third women were diagnosed with pathological gonadotroph hyperplasia due to primary gonadal insufficiency, with histopathological confirmation including gonadal-deficiency cells in the third case where surgery could have been avoided. The fourth woman likely had idiopathic PH, though she had concomitant polycystic ovary syndrome which is a debated cause of PH. Patients suspected of PH should undergo comprehensive hormonal, radiological and sometimes ophthalmological evaluation. This is best conducted by a specialised multidisciplinary team with preference for treatment of underlying conditions and close monitoring over surgical intervention. Learning points Normal pituitary dimensions are influenced by age and gender with the greatest pituitary heights seen in young adults and perimenopausal women.Pituitary enlargement may be seen in the settings of pregnancy, end-organ insufficiency with loss of negative feedback, and excess trophic hormone from the hypothalamus or neuroendocrine tumours.PH may be caused or exacerbated by medications including oestrogen, GNRH analogues and antipsychotics.Management involves identification of cases of idiopathic PH suitable for simple surveillance and reversal of pathological or iatrogenic causes where they exist.Surgery should be avoided in PH as it rarely progresses. PMID:26124954

Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms

DOE PAGES

Tang, Guoping; Zheng, Jianqiu; Xu, Xiaofeng; ...

2016-09-12

Soil organic carbon turnover to CO 2 and CH 4 is sensitive to soil redox potential and pH conditions. But, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximatelymore » describe the observed pH evolution without additional parameterization. Though Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. Furthermore, the equilibrium speciation predicts a substantial increase in CO 2 solubility as pH increases, and taking into account CO 2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO 2 production from closed microcosms can be substantially underestimated based on headspace CO 2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions.« less

Optimal Control Problems with Switching Points. Ph.D. Thesis, 1990 Final Report

NASA Technical Reports Server (NTRS)

Seywald, Hans

1991-01-01

The main idea of this report is to give an overview of the problems and difficulties that arise in solving optimal control problems with switching points. A brief discussion of existing optimality conditions is given and a numerical approach for solving the multipoint boundary value problems associated with the first-order necessary conditions of optimal control is presented. Two real-life aerospace optimization problems are treated explicitly. These are altitude maximization for a sounding rocket (Goddard Problem) in the presence of a dynamic pressure limit, and range maximization for a supersonic aircraft flying in the vertical, also in the presence of a dynamic pressure limit. In the second problem singular control appears along arcs with active dynamic pressure limit, which in the context of optimal control, represents a first-order state inequality constraint. An extension of the Generalized Legendre-Clebsch Condition to the case of singular control along state/control constrained arcs is presented and is applied to the aircraft range maximization problem stated above. A contribution to the field of Jacobi Necessary Conditions is made by giving a new proof for the non-optimality of conjugate paths in the Accessory Minimum Problem. Because of its simple and explicit character, the new proof may provide the basis for an extension of Jacobi's Necessary Condition to the case of the trajectories with interior point constraints. Finally, the result that touch points cannot occur for first-order state inequality constraints is extended to the case of vector valued control functions.

Correlation of Salivary pH, Incidence of Dental Caries and Periodontal Status in Diabetes Mellitus Patients: A Cross-sectional Study.

PubMed

Seethalakshmi, C; Reddy, R C Jagat; Asifa, Nisha; Prabhu, S

2016-03-01

Diabetes mellitus is a chronic disease affecting many parts of the body. A number of oral diseases have been associated with diabetes mellitus with an increased risk of dental caries and periodontal disease. The aim of the study was to evaluate the salivary pH and incidence of dental caries and periodontal status in diabetes mellitus compared to that of the normal subjects. The study population consisted of 40 patients divided into 2 groups with group I comprising of 20 known diabetes mellitus patients and group II comprising of 20 non diabetic subjects as control group. The pH of the saliva was determined using a digital pH meter. Dental caries and periodontal status were assessed by DMFT and PDI indices respectively. There was a decrease in the mean salivary pH of 6.51 in the study group, compared to the normal mean salivary pH of 7.88 in the control group. The mean DMFT index was higher in the study group (8.10) when compared to that of control group (1.15). The mean PDI score was also higher in the study group (4.0) as compared to that of the control group (0.45). The results of the present study concluded that there was a significant relationship between the diabetes mellitus and increased incidence of dental caries and periodontitis and there was also a significant reduction in the salivary pH in diabetes mellitus patients, compared to that of non diabetic subjects.

Correlation of Salivary pH, Incidence of Dental Caries and Periodontal Status in Diabetes Mellitus Patients: A Cross-sectional Study

PubMed Central

Reddy, R.C. Jagat; Asifa, Nisha; Prabhu, S.

2016-01-01

Introduction Diabetes mellitus is a chronic disease affecting many parts of the body. A number of oral diseases have been associated with diabetes mellitus with an increased risk of dental caries and periodontal disease. Aim The aim of the study was to evaluate the salivary pH and incidence of dental caries and periodontal status in diabetes mellitus compared to that of the normal subjects. Materials and Methods The study population consisted of 40 patients divided into 2 groups with group I comprising of 20 known diabetes mellitus patients and group II comprising of 20 non diabetic subjects as control group. The pH of the saliva was determined using a digital pH meter. Dental caries and periodontal status were assessed by DMFT and PDI indices respectively. Results There was a decrease in the mean salivary pH of 6.51 in the study group, compared to the normal mean salivary pH of 7.88 in the control group. The mean DMFT index was higher in the study group (8.10) when compared to that of control group (1.15). The mean PDI score was also higher in the study group (4.0) as compared to that of the control group (0.45). Conclusion The results of the present study concluded that there was a significant relationship between the diabetes mellitus and increased incidence of dental caries and periodontitis and there was also a significant reduction in the salivary pH in diabetes mellitus patients, compared to that of non diabetic subjects. PMID:27134992

Effects of a bacterial probiotic on ruminal pH and volatile fatty acids during subacute ruminal acidosis (SARA) in cattle

PubMed Central

GOTO, Hiroko; QADIS, Abdul Qadir; KIM, Yo-Han; IKUTA, Kentaro; ICHIJO, Toshihiro; SATO, Shigeru

2016-01-01

Effects of a bacterial probiotic (BP) on ruminal fermentation and plasma metabolites were evaluated in four Holstein cattle (body weight, 645 ± 62 kg; mean ± SD) with induced subacute ruminal acidosis (SARA). SARA was induced by feeding a SARA-inducing diet, and thereafter, 20, 50 or 100 g per head of a commercial BP was administered for 7 consecutive days during the morning feeding. Cattle without BP served as the control. The 24-hr mean ruminal pH in the control was lower, whereas those in the BP groups administered 20 or 50 g were significantly higher compared to the control from days 2 to 7. Circadian patterns of the 1-hr mean ruminal pH were identical (6.4–6.8) among all cattle receiving BP. Although the mean minimum pH in the control on day –7 and day 0 was <5.8, the pH in the treatment groups on day 7 was >5.8 and significantly higher than that of the control group ( >5.2). Ruminal volatile fatty acid (VFA) concentrations were not affected by BP treatment; however, the BP groups had lower lactic acid levels compared with the control group at 20:00 on day 7. Additionally, non-esterified fatty acid levels decreased from 8:00 to 20:00 in all BP groups on day 7. These results suggest that administration of 20 to 50 g of a multi-strain BP for 7 days might improve the low pH and high lactic acid level of the ruminal fluid in SARA cattle. PMID:27430197

Impact of a low intensity controlled-fire in some chemical soil properties.

NASA Astrophysics Data System (ADS)

Martínez-Murillo, Juan F.; Hueso-González, Paloma; Aranda-Gómez, Francisco; Damián Ruiz-Sinoga, José

2014-05-01

Some changes in chemical soil properties can be observed after fires of low intensities. pH and electric conductivity tend to increase, while C/N ratio decrease. In the case of organic matter, the content can increase due to the massive incorporation of necromass including, especially, plants and roots. The aim of this study is to assess the impact of low intensity and controlled fire in some soil properties in field conditions. El Pinarillo experimental area is located in South of Spain. Two set of closed plots were installed (24 m2: 12 m length x 2 m width). One of them was remained as control with the original vegetation cover (Mediterranean matorral: Rosmarinus officinalis, Cistus clusii, Lavandula stoechas, Chamaeropos humilis, Thymus baetica), and the other one was burnt in a controlled-fire in 2011. Weather conditions and water content of vegetation influenced in the intensity of fire (low). After the controlled-fire, soil surface sample (0-5 cm) were taken in both set of plots (B, burnt soil samples; C, control soil samples). Some soil chemical properties were analysed: organic matter content (OM), C/N ratio, pH and electrical conductivity (EC). Some changes were observed in B corroborating a controlled-fire of low intensity. pH remained equal after fire (B: pH=7.7±0.11; C: pH=7.7±0.04). An increment was obtained in the case of EC (B: EC=0.45 mScm-1±0.08 mScm-1; C: EC=0.35 mScm-1±0.07 mScm-1) and OM (B: OM=8.7%±3.8%; C: pH=7.3%±1.5%). Finally, C/N ratio decreased after fire respect to the control and initial conditions (B: C/N=39.0±14.6; C: C/N =46.5±10.2).

Photopic Negative Response Obtained Using a Handheld Electroretinogram Device: Determining the Optimal Measure and Repeatability

PubMed Central

Wu, Zhichao; Hadoux, Xavier; Hui, Flora; Sarossy, Marc G.; Crowston, Jonathan G.

2016-01-01

Purpose To determine the measure of the photopic negative response (PhNR) of the full-field electroretinogram (ERG) that exhibits the optimal level of test-retest repeatability, and examine its repeatability under different conditions using a handheld, nonmydriatic ERG system and self-adhering skin electrodes. Methods Multiple ERG recordings (using 200 sweeps each) were performed in both eyes of 20 normal participants at two different sessions to compare its coefficient of repeatability (CoR; where 95% of the test-retest difference is expected to lie) between different PhNR measures and under different testing conditions (within and between examiners, and between sessions). Results The ratio between the PhNR trough to b-wave peak and b-wave peak to a-wave trough amplitude (PhNR/B ratio) exhibited the lowest CoR relative to its effective dynamic range (30 ± 4%) when including three recordings. There were no significant changes in the PhNR/B ratio over seven measurements (4 right and 3 left eyes) at either session (P ≥ 0.100), or significant difference in its CoR between different testing conditions (P = 0.314). Conclusion The PhNR/B ratio was the measure that minimized variability, and its measurements using a novel handheld ERG system with self-adhering skin electrodes and the protocols described in this study were comparable under different testing conditions and over multiple recordings. Translational Relevance The PhNR can be measured for clinical and research purposes using a simple-to-implement technique that is consistent within and between visits, and also between examiners. PMID:27540494

The effect of surface charge on photocatalytic degradation of methylene blue dye using chargeable titania nanoparticles.

PubMed

Azeez, Fadhel; Al-Hetlani, Entesar; Arafa, Mona; Abdelmonem, Yasser; Nazeer, Ahmed Abdel; Amin, Mohamed O; Madkour, Metwally

2018-05-08

Herein, a simple approach based on tailoring the surface charge of nanoparticles, NPs, during the preparation to boost the electrostatic attraction between NPs and the organic pollutant was investigated. In this study, chargeable titania nanoparticles (TiΟ 2 NPs) were synthesized via a hydrothermal route under different pH conditions (pH = 1.6, 7.0 and 10). The prepared TiΟ 2 NPs were fully characterized via various techniques including; transmission electron microscopy (TEM), X-ray diffraction (XRD), N 2 adsorption/desorption, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible spectroscopy (UV-Vis) and dynamic light scattering (DLS). The influence of the preparation pH on the particle size, surface area and band gap was investigated and showed pH-dependent behavior. The results revealed that upon increasing the pH value, the particle size decreases and lead to larger surface area with less particles agglomeration. Additionally, the effect of pH on the surface charge was monitored by XPS to determine the amount of hydroxyl groups on the TiO 2 NPs surface. Furthermore, the photocatalytic activity of the prepared TiΟ 2 NPs towards methylene blue (MB) photodegradation was manifested. The variation in the preparation pH affected the point of zero charge (pH PZC ) of TiO 2 NPs, subsequently, different photocatalytic activities based on electrostatic interactions were observed. The optimum efficiency obtained was 97% at a degradation rate of 0.018 min -1 using TiO 2 NPs prepared at pH 10.

Evaluation of Gastric pH and Serum Gastrin Concentrations in Cats with Chronic Kidney Disease.

PubMed

Tolbert, M K; Olin, S; MacLane, S; Gould, E; Steiner, J M; Vaden, S; Price, J

2017-09-01

Chronic kidney disease (CKD) is a highly prevalent condition in cats. Advanced CKD is associated with hyporexia and vomiting, which typically are attributed to uremic toxins and gastric hyperacidity. However, gastric pH studies have not been performed in cats with CKD. To determine if cats with CKD have decreased gastric pH compared to age-matched, healthy cats. Based on previous work demonstrating an association of hypergastrinemia and CKD, we hypothesized that cats with CKD would have decreased gastric pH compared to healthy, age-matched control cats. 10 CKD cats; 9 healthy control cats. All cats with concurrent disease were excluded on the basis of history, physical examination, CBC, plasma biochemistry profile, urinalysis, urine culture, serum total thyroxine concentration, and serum symmetric dimethylarginine concentration (controls only) obtained within 24 hours of pH monitoring and assessment of serum gastrin concentrations. Serum for gastrin determination was collected, and 12-hour continuous gastric pH monitoring was performed in all cats. Serum gastrin concentration, mean pH, and percentage time that gastric pH was strongly acidic (pH <1 and <2) were compared between groups. No significant differences in serum gastrin concentrations were observed between groups (medians [range]: CKD, 18.7 ng/dL [<10-659.0]; healthy, 54.6 ng/dL [<10-98.0]; P-value = 0.713) or of any pH parameters including mean ± SD gastric pH (CKD, 1.8 ± 0.5; healthy, 1.6 ± 0.3; P-value = 0.23). These findings suggest that cats with CKD may not have gastric hyperacidity compared to healthy cats and, therefore, may not need acid suppression. Thus, further studies to determine if there is a benefit to acid suppression in cats with CKD are warranted. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Multiple, simultaneous, independent gradients for a versatile multidimensional liquid chromatography. Part II: Application 2: Computer controlled pH gradients in the presence of urea provide improved separation of proteins: Stability influenced anion and cation exchange chromatography.

PubMed

Hirsh, Allen G; Tsonev, Latchezar I

2017-04-28

This paper details the use of a method of creating controlled pH gradients (pISep) to improve the separation of protein isoforms on ion exchange (IEX) stationary phases in the presence of various isocratic levels of urea. The pISep technology enables the development of computer controlled pH gradients on both cationic (CEX) and anionic (AEX) IEX stationary phases over the very wide pH range from 2 to 12. In pISep, titration curves generated by proportional mixing of the acidic and basic pISep working buffers alone, or in the presence of non-buffering solutes such as the neutral salt NaCl (0-1M), polar organics such as urea (0-8M) or acetonitrile (0-80 Vol%), can be fitted with high fidelity using high order polynomials which, in turn allows construction of a mathematical manifold %A (% acidic pISep buffer) vs. pH vs. [non-buffering solute], permitting precise computer control of pH and the non-buffering solute concentration allowing formation of dual uncoupled liquid chromatographic (LC) gradients of arbitrary shape (Hirsh and Tsonev, 2012 [1]). The separation of protein isoforms examined in this paper by use of such pH gradients in the presence of urea demonstrates the fractionation power of a true single step two dimensional liquid chromatography which we denote as Stability-Influenced Ion Exchange Chromatography (SIIEX). We present evidence that SIIEX is capable of increasing the resolution of protein isoforms difficult to separate by ordinary pH gradient IEX, and potentially simplifying the development of laboratory and production purification strategies involving on-column simultaneous pH and urea unfolding or refolding of targeted proteins. We model some of the physics implied by the dynamics of the observed protein fractionations as a function of both urea concentration and pH assuming that urea-induced native state unfolding competes with native state electrostatic interaction binding to an IEX stationary phase. Implications for in vivo protein-membrane interactions are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of an Alkali- and Halide-Resistant Laccase Expressed in E. coli: CotA from Bacillus clausii

PubMed Central

Brander, Søren; Mikkelsen, Jørn D.; Kepp, Kasper P.

2014-01-01

The limitations of fungal laccases at higher pH and salt concentrations have intensified the search for new extremophilic bacterial laccases. We report the cloning, expression, and characterization of the bacterial cotA from Bacillus clausii, a supposed alkalophilic ortholog of cotA from B. subtilis. Both laccases were expressed in E. coli strain BL21(DE3) and characterized fully in parallel for strict benchmarking. We report activity on ABTS, SGZ, DMP, caffeic acid, promazine, phenyl hydrazine, tannic acid, and bilirubin at variable pH. Whereas ABTS, promazine, and phenyl hydrazine activities vs. pH were similar, the activity of B. clausii cotA was shifted upwards by ∼0.5–2 pH units for the simple phenolic substrates DMP, SGZ, and caffeic acid. This shift is not due to substrate affinity (KM) but to pH dependence of catalytic turnover: The kcat of B. clausii cotA was 1 s−1 at pH 6 and 5 s−1 at pH 8 in contrast to 6 s−1 at pH 6 and 2 s−1 at pH 8 for of B. subtilis cotA. Overall, kcat/KM was 10-fold higher for B. subtilis cotA at pHopt. While both proteins were heat activated, activation increased with pH and was larger in cotA from B. clausii. NaCl inhibited activity at acidic pH, but not up to 500–700 mM NaCl in alkaline pH, a further advantage of the alkali regime in laccase applications. The B. clausii cotA had ∼20 minutes half-life at 80°C, less than the ∼50 minutes at 80°C for cotA from B. subtilis. While cotA from B. subtilis had optimal stability at pH∼8, the cotA from B. clausii displayed higher combined salt- and alkali-resistance. This resistance is possibly caused by two substitutions (S427Q and V110E) that could repel anions to reduce anion-copper interactions at the expense of catalytic proficiency, a trade-off of potential relevance to laccase optimization. PMID:24915287

Exhaled breath condensate pH assays are not influenced by oral ammonia

PubMed Central

Wells, K; Vaughan, J; Pajewski, T; Hom, S; Ngamtrakulpanit, L; Smith, A; Nguyen, A; Turner, R; Hunt, J

2005-01-01

Background: Measurement of pH in exhaled breath condensate (EBC) is robust and simple. Acidic source fluid (airway lining fluid) traps bases while volatilising acids, leading to EBC acidification in many lung diseases. Lower airway ammonia is one determinant of airway lining fluid pH, raising the concern that addition of the base ammonia by contamination from the mouth might confound EBC pH assays. Methods: Three discrete methods were used to limit oral ammonia contamination of EBC collections: endotracheal intubation, oral rinsing, and –40°C condenser temperatures. Separately, ammonia was removed from collected EBC samples by lyophilisation and resuspension. Intraweek and intraday variability of ammonia concentration was determined in 76 subjects, and ammonia and pH from a further 235 samples were graphically compared. Ammonia was assayed spectrophotometrically and pH was assessed after deaeration. Results: Data from 1091 samples are presented. Ammonia was reduced in EBC by all methods. Endotracheal intubation decreased EBC ammonia from a mean (SD) of 619 (124) µM to 80 (24) µM (p<0.001, n = 32). Oral rinsing before collection also led to a decline in EBC ammonia from 573 (307) µM to 224 (80) µM (p = 0.016, n = 7). The colder the condensation temperature used, the less ammonia was trapped in the EBC. Lyophilisation removed 99.4 (1.9)% of ammonia. Most importantly, the pH of EBC never decreased after removal of ammonia by any of these methods. Intraweek and intraday coefficients of variation for ammonia were 64 (27)% and 60 (32)%, which is substantially more variable than EBC pH assays. Conclusions: Although ammonia and pH appear to correlate in EBC, the oral ammonia concentration is not an important determinant of EBC pH. No precautions need to be taken to exclude oral ammonia when EBC pH is of interest. The low pH and low ammonia found in EBC from patients with lung diseases appear to be independent effects of volatile compounds arising from the airway. PMID:15618579

Electrochemical Induced Calcium Phosphate Precipitation: Importance of Local pH

PubMed Central

2017-01-01

Phosphorus (P) is an essential nutrient for living organisms and cannot be replaced or substituted. In this paper, we present a simple yet efficient membrane free electrochemical system for P removal and recovery as calcium phosphate (CaP). This method relies on in situ formation of hydroxide ions by electro mediated water reduction at a titanium cathode surface. The in situ raised pH at the cathode provides a local environment where CaP will become highly supersaturated. Therefore, homogeneous and heterogeneous nucleation of CaP occurs near and at the cathode surface. Because of the local high pH, the P removal behavior is not sensitive to bulk solution pH and therefore, efficient P removal was observed in three studied bulk solutions with pH of 4.0 (56.1%), 8.2 (57.4%), and 10.0 (48.4%) after 24 h of reaction time. While P removal efficiencies are not generally affected by bulk solution pH, the chemical-physical properties of CaP solids collected on the cathode are still related to bulk solution pH, as confirmed by structure characterizations. High initial solution pH promotes the formation of more crystalline products with relatively high Ca/P molar ratio. The Ca/P molar ratio increases from 1.30 (pH 4.0) to 1.38 (pH 8.2) and further increases to 1.55 (pH 10.0). The formation of CaP precipitates was a typical crystallization process, with an amorphous phase formed at the initial stage which then transforms to the most stable crystal phase, hydroxyapatite, which is inferred from the increased Ca/P molar ratio from 1.38 (day 1) to the theoretical 1.76 (day 11) and by the formation of needle-like crystals. Finally, we demonstrated the efficiency of this system for real wastewater. This, together with the fact that the electrochemical method can work at low bulk pH, without dosing chemicals and a need for a separation process, highlights the potential application of the electrochemical method for P removal and recovery. PMID:28872838

Aqueous biphasic extraction process with pH and particle control

DOEpatents

Chaiko, David J.; Mensah-Biney, R.

1995-01-01

A process for aqueous biphasic extraction of metallic oxides and the like from substances containing silica. Control of media pH enables efficient and effective partition of mixture components. The inventive method may be employed to remove excess silica from kaolin clay.

Efficient and reproducible mammalian cell bioprocesses without probes and controllers?

PubMed

Tissot, Stéphanie; Oberbek, Agata; Reclari, Martino; Dreyer, Matthieu; Hacker, David L; Baldi, Lucia; Farhat, Mohamed; Wurm, Florian M

2011-07-01

Bioprocesses for recombinant protein production with mammalian cells are typically controlled for several physicochemical parameters including the pH and dissolved oxygen concentration (DO) of the culture medium. Here we studied whether these controls are necessary for efficient and reproducible bioprocesses in an orbitally shaken bioreactor (OSR). Mixing, gas transfer, and volumetric power consumption (P(V)) were determined in both a 5-L OSR and a 3-L stirred-tank bioreactor (STR). The two cultivation systems had a similar mixing intensity, but the STR had a lower volumetric mass transfer coefficient of oxygen (k(L)a) and a higher P(V) than the OSR. Recombinant CHO cell lines expressing either tumor necrosis factor receptor as an Fc fusion protein (TNFR:Fc) or an anti-RhesusD monoclonal antibody were cultivated in the two systems. The 5-L OSR was operated in an incubator shaker with 5% CO(2) in the gas environment but without pH and DO control whereas the STR was operated with or without pH and DO control. Higher cell densities and recombinant protein titers were obtained in the OSR as compared to both the controlled and the non-controlled STRs. To test the reproducibility of a bioprocess in a non-controlled OSR, the two CHO cell lines were each cultivated in parallel in six 5-L OSRs. Similar cell densities, cell viabilities, and recombinant protein titers along with similar pH and DO profiles were achieved in each group of replicates. Our study demonstrated that bioprocesses can be performed in OSRs without pH or DO control in a highly reproducible manner, at least at the scale of operation studied here. Copyright © 2011 Elsevier B.V. All rights reserved.

Defining a Clinically Meaningful Effect for the Design and Interpretation of Randomized Controlled Trials

PubMed Central

Kraemer, Helena C.; Epstein, Robert S.; Frank, Ellen; Haynes, Ginger; Laughren, Thomas P.; Mcnulty, James; Reed, Shelby D.; Sanchez, Juan; Leon, Andrew C.

2013-01-01

Objective: This article captures the proceedings of a meeting aimed at defining clinically meaningful effects for use in randomized controlled trials for psychopharmacological agents. Design: Experts from a variety of disciplines defined clinically meaningful effects from their perspectives along with viewpoints about how to design and interpret randomized controlled trials. Setting: The article offers relevant, practical, and sometimes anecdotal information about clinically meaningful effects and how to interpret them. Participants: The concept for this session was the work of co-chairs Richard Keefe and the late Andy Leon. Faculty included Richard Keefe, PhD; James McNulty, AbScB; Robert S. Epstein, MD, MS; Shelby D. Reed, PhD; Juan Sanchez, MD; Ginger Haynes, PhD; Andrew C. Leon, PhD; Helena Chmura Kraemer, PhD; Ellen Frank, PhD, and Kenneth L. Davis, MD. Results: The term clinically meaningful effect is an important aspect of designing and interpreting randomized controlled trials but can be particularly difficult in the setting of psychopharmacology where effect size may be modest, particularly over the short term, because of a strong response to placebo. Payers, regulators, patients, and clinicians have different concerns about clinically meaningful effects and may describe these terms differently. The use of moderators in success rate differences may help better delineate clinically meaningful effects. Conclusion: There is no clear consensus on a single definition for clinically meaningful differences in randomized controlled trials, and investigators must be sensitive to specific concerns of stakeholders in psychopharmacology in order to design and execute appropriate clinical trials. PMID:23882433

Glutamine prevents oxidative stress in a model of portal hypertension.

PubMed

Zabot, Gilmara Pandolfo; Carvalhal, Gustavo Franco; Marroni, Norma Possa; Licks, Francielli; Hartmann, Renata Minuzzo; da Silva, Vinícius Duval; Fillmann, Henrique Sarubbi

2017-07-07

To evaluate the protective effects of glutamine in a model of portal hypertension (PH) induced by partial portal vein ligation (PPVL). Male Wistar rats were housed in a controlled environment and were allowed access to food and water ad libitum . Twenty-four male Wistar rats were divided into four experimental groups: (1) control group (SO) - rats underwent exploratory laparotomy; (2) control + glutamine group (SO + G) - rats were subjected to laparotomy and were treated intraperitoneally with glutamine; (3) portal hypertension group (PPVL) - rats were subjected to PPVL; and (4) PPVL + glutamine group (PPVL + G) - rats were treated intraperitoneally with glutamine for seven days. Local injuries were determined by evaluating intestinal segments for oxidative stress using lipid peroxidation and the activities of glutathione peroxidase (GPx), endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) after PPVL. Lipid peroxidation of the membrane was increased in the animals subjected to PH ( P < 0.01). However, the group that received glutamine for seven days after the PPVL procedure showed levels of lipid peroxidation similar to those of the control groups ( P > 0.05). The activity of the antioxidant enzyme GTx was decreased in the gut of animals subjected to PH compared with that in the control group of animals not subjected to PH ( P < 0.01). However, the group that received glutamine for seven days after the PPVL showed similar GTx activity to both the control groups not subjected to PH ( P > 0.05). At least 10 random, non-overlapping images of each histological slide with 200 × magnification (44 pixel = 1 μm) were captured. The sum means of all areas, of each group were calculated. The mean areas of eNOS staining for both of the control groups were similar. The PPVL group showed the largest area of staining for eNOS. The PPVL + G group had the second highest amount of staining, but the mean value was much lower than that of the PPVL group ( P < 0.01). For iNOS, the control (SO) and control + G (SO + G) groups showed similar areas of staining. The PPVL group contained the largest area of iNOS staining, followed by the PPVL + G group; however, this area was significantly smaller than that of the group that underwent PH without glutamine ( P < 0.01). Treatment with glutamine prevents gut mucosal injury after PH in rats.

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Arca inflata Reeve

NASA Astrophysics Data System (ADS)

Li, Jiaqi; Jiang, Zengjie; Zhang, Jihong; Mao, Yuze; Bian, Dapeng; Fang, Jianguang

2014-11-01

We evaluated the effect of pH on larval development in larval Pacific oyster ( Crassostrea gigas) and blood cockle ( Arca inflata Reeve). The larvae were reared at pH 8.2 (control), 7.9, 7.6, or 7.3 beginning 30 min or 24 h post fertilization. Exposure to lower pH during early embryonic development inhibited larval shell formation in both species. Compared with the control, larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3. Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3. However, when exposure was delayed until 24 h post fertilization, shell formation was only inhibited in blood cockle larvae reared at pH 7.3. Thus, the early embryonic stages were more sensitive to acidified conditions. Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves. Although the effects appear subtle, they may accumulate and lead to subsequent issues during later larval development.

Effect of root canal obturation with calcium silicate materials on pH change in simulated root resorption defects.

PubMed

Aggarwal, Vivek; Singla, Mamta; Miglani, Sanjay; Sharma, Ritu

2018-01-01

This study evaluated the effect of 3 commercially available calcium silicate materials (CSMs) on pH changes in simulated root resorption defects. Simulated root resorption defects were prepared on the facial root surface of 40 mandibular premolars. The depth of each defect was individually calculated to standardize the remaining dentin thickness to 1 mm. Prepared canals were obturated with the 3 CSMs. Ten specimens were kept as controls, filled with unbuffered normal saline. The pH measurements were taken at 1 hour, 6 hours, 1 day, 1 week, 2 weeks, 3 weeks, 1 month, and 2 months. All CSM groups exhibited an initial alkaline pH of 9.0-9.7. The pH decreased to 8.0-8.5 after 2 months of storage. There were no significant differences between pH measurements at other time intervals. The CSM groups exhibited higher pH levels than the control group. The results showed that intracanal placement of the CSMs maintained initial pH levels of 9.0-9.7 inside the simulated resorption defects; these measurements gradually decreased to 8.0-8.5 over the span of 2 months.

Controllable synthesis of green and blue fluorescent carbon nanodots for pH and Cu(2+) sensing in living cells.

PubMed

Shi, Lihong; Li, Yanyan; Li, Xiaofeng; Zhao, Bo; Wen, Xiangping; Zhang, Guomei; Dong, Chuan; Shuang, Shaomin

2016-03-15

We report a controllable strategy for fabrication of green and blue fluorescent carbon nanodots (CDs), and demonstrate their applications for pH and Cu(2+) sensing in living cells. Green and blue fluorescent CDs have been synthesized by hydrothermal method and pyrolysis of leeks, respectively, providing an easy way for the production of CDs without the request of tedious synthetic methodology or the use of toxic/expensive solvents and starting materials. Green fluorescent CDs (G-CDs) exhibit high tolerance to pH values and external cations. Blue fluorescent CDs (B-CDs) can be applied to pH and Cu(2+) sensing. The linear range of Cu(2+) detection is 0.01-10.00 μM and the detection limit is 0.05 μM. For pH detection, there is a good linearity in the pH range of 3.5-10.0. The linear and rapid response of B-CDs to Cu(2+) and pH is valuable for Cu(2+) and pH sensing in living cells. Confocal fluorescent imaging of human cervical carcinoma cells indicates that B-CDs could visualize Cu(2+) and pH fluctuations in living cells with negligible autofluorescence. Copyright © 2015 Elsevier B.V. All rights reserved.

The chemistry, physiology and pathology of pH in cancer

PubMed Central

Swietach, Pawel; Vaughan-Jones, Richard D.; Harris, Adrian L.; Hulikova, Alzbeta

2014-01-01

Cell survival is conditional on the maintenance of a favourable acid–base balance (pH). Owing to intensive respiratory CO2 and lactic acid production, cancer cells are exposed continuously to large acid–base fluxes, which would disturb pH if uncorrected. The large cellular reservoir of H+-binding sites can buffer pH changes but, on its own, is inadequate to regulate intracellular pH. To stabilize intracellular pH at a favourable level, cells control trans-membrane traffic of H+-ions (or their chemical equivalents, e.g. ) using specialized transporter proteins sensitive to pH. In poorly perfused tumours, additional diffusion-reaction mechanisms, involving carbonic anhydrase (CA) enzymes, fine-tune control extracellular pH. The ability of H+-ions to change the ionization state of proteins underlies the exquisite pH sensitivity of cellular behaviour, including key processes in cancer formation and metastasis (proliferation, cell cycle, transformation, migration). Elevated metabolism, weakened cell-to-capillary diffusive coupling, and adaptations involving H+/H+-equivalent transporters and extracellular-facing CAs give cancer cells the means to manipulate micro-environmental acidity, a cancer hallmark. Through genetic instability, the cellular apparatus for regulating and sensing pH is able to adapt to extracellular acidity, driving disease progression. The therapeutic potential of disturbing this sequence by targeting H+/H+-equivalent transporters, buffering or CAs is being investigated, using monoclonal antibodies and small-molecule inhibitors. PMID:24493747

The chemistry, physiology and pathology of pH in cancer.

PubMed

Swietach, Pawel; Vaughan-Jones, Richard D; Harris, Adrian L; Hulikova, Alzbeta

2014-03-19

Cell survival is conditional on the maintenance of a favourable acid-base balance (pH). Owing to intensive respiratory CO2 and lactic acid production, cancer cells are exposed continuously to large acid-base fluxes, which would disturb pH if uncorrected. The large cellular reservoir of H(+)-binding sites can buffer pH changes but, on its own, is inadequate to regulate intracellular pH. To stabilize intracellular pH at a favourable level, cells control trans-membrane traffic of H(+)-ions (or their chemical equivalents, e.g. ) using specialized transporter proteins sensitive to pH. In poorly perfused tumours, additional diffusion-reaction mechanisms, involving carbonic anhydrase (CA) enzymes, fine-tune control extracellular pH. The ability of H(+)-ions to change the ionization state of proteins underlies the exquisite pH sensitivity of cellular behaviour, including key processes in cancer formation and metastasis (proliferation, cell cycle, transformation, migration). Elevated metabolism, weakened cell-to-capillary diffusive coupling, and adaptations involving H(+)/H(+)-equivalent transporters and extracellular-facing CAs give cancer cells the means to manipulate micro-environmental acidity, a cancer hallmark. Through genetic instability, the cellular apparatus for regulating and sensing pH is able to adapt to extracellular acidity, driving disease progression. The therapeutic potential of disturbing this sequence by targeting H(+)/H(+)-equivalent transporters, buffering or CAs is being investigated, using monoclonal antibodies and small-molecule inhibitors.

Theory and applications of a novel ion exchange chromatographic technology using controlled pH gradients for separating proteins on anionic and cationic stationary phases.

PubMed

Tsonev, Latchezar I; Hirsh, Allen G

2008-07-25

pISep is a major new advance in low ionic strength ion exchange chromatography. It enables the formation of externally controlled pH gradients over the very broad pH range from 2 to 12. The gradients can be generated on either cationic or anionic exchangers over arbitrary pH ranges wherein the stationary phases remain totally charged. Associated pISep software makes possible the calculation of either linear, nonlinear or combined, multi-step, multi-slope pH gradients. These highly reproducible pH gradients, while separating proteins and glycoproteins in the order of their electrophoretic pIs, provide superior chromatographic resolution compared to salt. This paper also presents a statistical mechanical model for protein binding to ion exchange stationary phases enhancing the electrostatic interaction theory for the general dependence of retention factor k, on both salt and pH simultaneously. It is shown that the retention factors computed from short time isocratic salt elution data of a model protein can be used to accurately predict its salt elution concentration in varying slope salt elution gradients formed at varying isocratic pH as well as the pH at which it will be eluted from an anionic exchange column by a pISep pH gradient in the absence of salt.

Salivary buffer capacity, pH, and stimulated flow rate of crack cocaine users.

PubMed

Woyceichoski, Iverson Ernani Cogo; Costa, Carlos Henrique; de Araújo, Cristiano Miranda; Brancher, João Armando; Resende, Luciane Grochocki; Vieira, Iran; de Lima, Antonio Adilson Soares

2013-08-01

Crack cocaine is the freebase form of cocaine that can be smoked. The use of this drug has been considered a public health problem in many countries. The aim of this study was to assess the stimulated salivary flow rate (SSFR), pH, and the buffer capacity of saliva in crack cocaine users. Stimulated whole saliva was collected from 54 selected crack cocaine users and 40 non-users. All samples were analyzed for SSFR, pH, and buffer capacity. SSFR was analyzed by gravimetric method. The buffer capacity and pH were determined using a digital pH meter. The crack cocaine users demonstrated higher buffer capacity than the control group (P > 0.05). Salivary pH was lower in crack cocaine users (P < 0.05). Mean values of the SSFR for the experimental and control groups were 1.1 and 1.3 mL/min, respectively (P > 0.05). Crack cocaine users might exhibit a significant decrease in salivary pH, but not in salivary flow rate or buffer capacity. © 2012 Blackwell Publishing Asia Pty Ltd.

Accelerated dissolution testing for controlled release microspheres using the flow-through dissolution apparatus.

PubMed

Collier, Jarrod W; Thakare, Mohan; Garner, Solomon T; Israel, Bridg'ette; Ahmed, Hisham; Granade, Saundra; Strong, Deborah L; Price, James C; Capomacchia, A C

2009-01-01

Theophylline controlled release capsules (THEO-24 CR) were used as a model system to evaluate accelerated dissolution tests for process and quality control and formulation development of controlled release formulations. Dissolution test acceleration was provided by increasing temperature, pH, flow rate, or adding surfactant. Electron microscope studies on the theophylline microspheres subsequent to each experiment showed that at pH values of 6.6 and 7.6 the microspheres remained intact, but at pH 8.6 they showed deterioration. As temperature was increased from 37-57 degrees C, no change in microsphere integrity was noted. Increased flow rate also showed no detrimental effect on integrity. The effect of increased temperature was determined to be the statistically significant variable.

ITCS Test Strip Development and Certification

NASA Technical Reports Server (NTRS)

Carrigan, Caitlin; Adam, Niklas; Pickering, Karen; Gazda, Daniel; Piowaty, Hailey

2011-01-01

Internal coolant loops used for International Space Station thermal control must be periodically monitored for system health, including pH, biocide levels and any indication of ammonia. The presence of ammonia, possible via a microleak in the interface between the internal and external thermal control systems, could be a danger to the crew. The Internal Thermal Control System (ITCS) Sampling Kit uses test strips as a colorimetric indicator of pH and concentrations of biocide and free ammonia. This paper describes the challenges in designing an ammonia colorimetric indicator in a variable pH environment, as well as lessons learned, ultimately resulting in a robust test strip to indicate a hazardous ammonia leak.

Development and validation of a simple and robust method for arsenic speciation in human urine using HPLC/ICP-MS.

PubMed

Sen, Indranil; Zou, Wei; Alvaran, Josephine; Nguyen, Linda; Gajek, Ryszard; She, Jianwen

2015-01-01

In order to better distinguish the different toxic inorganic and organic forms of arsenic (As) exposure in individuals, we have developed and validated a simple and robust analytical method for determining the following six As species in human urine: arsenous (III) acid (As-III), As (V) acid, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine (AsB), and arsenocholine. In this method, human urine is diluted using a pH 5.8 buffer, separation is performed using an anion exchange column with isocratic HPLC, and detection is achieved using inductively coupled plasma-MS. The method uses a single mobile phase consisting of low concentrations of both phosphate buffer (5 mM) and ammonium nitrate salt (5 mM) at pH 9.0; this minimizes the column equilibration time and overcomes challenges with separation between AsB and As-III. In addition, As-III oxidation is prevented by degassing the sample preparation buffer at pH 5.8, degassing the mobile phase online at pH 9.0, and by the use of low temperature (-70 °C) and flip-cap airtight tubes for long term storage of samples. The method was validated using externally provided reference samples. Results were in agreement with target values at varying concentrations and successfully passed external performance test criteria. Internal QC samples were prepared and repeatedly analyzed to assess the method's long-term precision, and further analyses were completed on anonymous donor urine to assess the quality of the method's baseline separation. Results from analyses of external reference samples agreed with target values at varying concentrations, and results from precision studies yielded absolute CV values of 3-14% and recovery from 82 to 115% for the six As species. Analysis of anonymous donor urine confirmed the well-resolved baseline separation capabilities of the method for real participant samples.

Ionic calcium determination in skim milk with molecular probes and front-face fluorescence spectroscopy: simple linear regression.

PubMed

Gangidi, R R; Metzger, L E

2006-11-01

The purpose of this study was to determine if the ionic calcium content of skim milk could be determined using molecular probes and front-face fluorescence spectroscopy. Current methods for determining ionic calcium are not sensitive, overestimate ionic calcium, or require complex procedures. Molecular probes designed specifically for measuring ionic calcium could potentially be used to determine the ionic calcium content of skim milk. The goal of the current study was to develop foundation methods for future studies to determine ionic calcium directly in skim milk and other dairy products with molecular probes and fluorescence spectroscopy. In this study, the effect of pH on calcium-sensitive fluorescent probe (Rhod-5N and Fluo-5N) performance using various concentrations of skim milk was determined. The pH of diluted skim milk (1.9 to 8.9% skim milk), was adjusted to either 6.2 or 7.0, after which the samples were analyzed with fluorescent probes (1 microM) and front-face fluorescence spectroscopy. The ionic calcium content of each sample was also determined using a calcium ion-selective electrode. The results demonstrated that the ionic calcium content of each sample was highly correlated (R2 > 0.989) with the fluorescence intensities of the probe-calcium adduct using simple linear regression. Higher than suggested ionic calcium contents of 1,207 and 1,973 microM were determined with the probes (Fluo-5N and Rhod-5N) in diluted skim milk with pH 7.0 and 6.2, respectively. The fluorescence intensity of the probe-calcium adduct decreased with a decrease in pH for the same ionic calcium concentration. This study demonstrates that Fluo-5N and Rhod-5N can be used to determine the ionic-calcium content of diluted milk with front-face fluorescence spectroscopy. Furthermore, these probes may also have the potential to determine the ionic calcium content of undiluted skim milk.

Influence of pH control in the formation of inclusion bodies during production of recombinant sphingomyelinase-D in Escherichia coli.

PubMed

Castellanos-Mendoza, Andrea; Castro-Acosta, Ricardo M; Olvera, Alejandro; Zavala, Guadalupe; Mendoza-Vera, Miguel; García-Hernández, Enrique; Alagón, Alejandro; Trujillo-Roldán, Mauricio A; Valdez-Cruz, Norma A

2014-09-12

Inclusion bodies (IBs) are aggregated proteins that form clusters when protein is overexpressed in heterologous expression systems. IBs have been considered as non-usable proteins, but recently they are being used as functional materials, catalytic particles, drug delivery agents, immunogenic structures, and as a raw material in recombinant therapeutic protein purification. However, few studies have been made to understand how culture conditions affect the protein aggregation and the physicochemical characteristics that lead them to cluster. The objective of our research was to understand how pH affects the physicochemical properties of IBs formed by the recombinant sphingomyelinase-D of tick expressed in E. coli BL21-Gold (DE3) by evaluating two pH culture strategies. Uncontrolled pH culture conditions favored recombinant sphingomyelinase-D aggregation and IB formation. The IBs of sphingomyelinase-D produced under controlled pH at 7.5 and after 24 h were smaller (<500 nm) than those produced under uncontrolled pH conditions (>500 nm). Furthermore, the composition, conformation and β-structure formation of the aggregates were different. Under controlled pH conditions in comparison to uncontrolled conditions, the produced IBs presented higher resistance to denaturants and proteinase-K degradation, presented β-structure, but apparently as time passes the IBs become compacted and less sensitive to amyloid dye binding. The manipulation of the pH has an impact on IB formation and their physicochemical characteristics. Particularly, uncontrolled pH conditions favored the protein aggregation and sphingomyelinase-D IB formation. The evidence may lead to find methodologies for bioprocesses to obtain biomaterials with particular characteristics, extending the application possibilities of the inclusion bodies.

Lung tissue remodelling in MCT-induced pulmonary hypertension: a proposal for a novel scoring system and changes in extracellular matrix and fibrosis associated gene expression.

PubMed

Franz, Marcus; Grün, Katja; Betge, Stefan; Rohm, Ilonka; Ndongson-Dongmo, Bernadin; Bauer, Reinhard; Schulze, P Christian; Lichtenauer, Michael; Petersen, Iver; Neri, Dario; Berndt, Alexander; Jung, Christian

2016-12-06

Pulmonary hypertension (PH) is associated with vasoconstriction and remodelling. We studied lung tissue remodelling in a rat model of PH with special focus on histology and extracellular matrix (ECM) remodelling. After induction of PH by monocrotaline, lung tissue was analysed histologically, by gene expression analysis and immunofluorescence labelling of ED-A domain containing fibronectin (ED-A+ Fn), B domain containing tenascin-C (B+ Tn-C) as well as alpha-smooth muscle actin (α-SMA). Serum concentrations of ED-A+ Fn were determined by ELISA. Systolic right ventricular pressure (RVPsys) values were significantly elevated in PH (n = 18; 75 ± 26.4 mmHg) compared to controls (n = 10; 29 ± 19.3 mmHg; p = 0.015). The histological sum-score was significantly increased in PH (8.0 ± 2.2) compared to controls (2.5 ± 1.6; p < 0.001). Gene expression analysis revealed relevant induction of several key genes of extracellular matrix remodelling. Increased protein deposition of ED-A+ Fn but not of B+ Tn-C and α-SMA in lung tissue was found in PH (2.88 ± 3.19 area%) compared to controls (1.32 ± 0.16 area%; p = 0.030). Serum levels of ED-A+ Fn were significantly higher in PH (p = 0.007) positively correlating with RVPsys (r = 0.618, p = 0.019). We here present a novel histological scoring system to assess lung tissue remodelling in PH. Gene expression analysis revealed induction of candidate genes involved in collagen matrix turnover, fibrosis and vascular remodelling. The stable increased tissue deposition of ED-A+ Fn in PH as well as its dynamics in serum suggests a role as a promising novel biomarker and potential therapeutic target.

Campylobacter, Salmonella, and Escherichia coli on broiler carcasses subjected to a high pH scald and low pH postpick chlorine dip.

PubMed

Berrang, M E; Windham, W R; Meinersmann, R J

2011-04-01

The objective of this study was to determine the individual and combined effects of a high pH scald and a postpick chlorine dip on bacteria present on broiler carcasses. In each of 3 replications, a flock was sampled at several sites within a commercial broiler processing plant. Carcasses were sampled by whole carcass rinse before and after treated scalding at mean pH 9.89 or control scalding at mean pH 6.88. Other carcasses from the same flock run on both the treated and control scald lines were collected and sampled before and after a chlorine dip tank operated at mean total chlorine level of 83.3 mg/kg and pH 6.04. Rinses were cultured for numbers of Campylobacter and Escherichia coli and presence or absence of Salmonella. High pH scald was more effective than standard scald to lessen the prevalence and numbers of Campylobacter on broiler carcasses; a lower prevalence was maintained through the postpick chlorine dip tank. The pH of the scald tank made no difference in numbers of E. coli recovered from broiler carcasses at any tested point on the processing line. High pH scald was not more effective than standard scald to lessen Salmonella prevalence. Furthermore, it is unclear why the postpick chlorine dip effectively lessened Salmonella prevalence on only the control scald line. Although no evidence exists that these treatments have an additive effect when used in series, each treatment shows some promise individually. Further optimization may result in more effective decontamination of broiler carcasses.

Acidogenic fermentation of iron-enhanced primary sedimentation sludge under different pH conditions for production of volatile fatty acids.

PubMed

Lin, Lin; Li, Xiao-Yan

2018-03-01

Iron-based chemically enhanced primary sedimentation (CEPS) is increasingly adopted for wastewater treatment in mega cities, producing a large amount of sludge (Fe-sludge) with a high content of organics for potential organic resource recovery. In this experimental study, acidogenic fermentation was applied treat FeCl 3 -based CEPS sludge for production of volatile fatty acids (VFAs) at different pHs. Batch fermentation tests on the Fe-sludge with an organic content of 10 g-COD/L showed that the maximum VFAs production reached 2782.2 mg-COD/L in the reactor without pH control, and it reached 688.4, 3095.3, and 2603.7 mg-COD/L in reactors with pHs kept at 5.0, 6.0 and 8.0, respectively. Analysis of the acidogenesis kinetics and enzymatic activity indicated that the alkaline pH could accelerate the rate of organic hydrolysis but inhibited the further organic conversion to VFAs. In semi-continuous sludge fermentation tests, the VFAs yield in the pH6 reactor was 20% higher than that in the control reactor without pH regulation, while the VFAs yield in the pH8 reactor was 10% lower than the control. Illumina MiSeq sequencing revealed that key functional microorganisms known for effective sludge fermentation, including Bacteroidia and Erysipelotrichi, were enriched in the pH6 reactor with an enhanced VFAs production, while Clostridia became more abundant in the pH8 reactor to stand the unfavorable pH condition. The research presented acidogenic fermentation as an effective process for CEPS sludge treatment and organic resource recovery and provided the first insight into the related microbial community dynamics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production of pigment-free pullulan by swollen cell in Aureobasidium pullulans NG which cell differentiation was affected by pH and nutrition.

PubMed

Li, Bing-xue; Zhang, Ning; Peng, Qing; Yin, Tie; Guan, Fei-fei; Wang, Gui-li; Li, Ying

2009-08-01

A black yeast strain "NG" was isolated from strawberry fruit and identified as Aureobasidium pullulans. Strain NG displayed yeast-like cell (YL), swollen cell (SC), septate swollen cell (SSC), meristematic structure (MS), and chlamydospore (CH) morphologies. pH was the key factor regulating cell morphogenesis of strain NG. Differentiation of YL controlled by extracellular pH had no relationship with nutrition level. YL was maintained at pH >6.0, but was transformed into SC at pH approximately 4.5. SC, a stable cell type of A. pullulans, could bud, septate, or transform into MS or CH, in response to nutrition level and low pH. SC produced swollen cell blastospores (SCB) at pH 2.1 with abundant nutrition, and could transform into MS at lower pH (1.5). SC was induced to form CH by low level nutrition and pH <3, and this transition was suppressed by adjusting pH to approximately 4.5. Crude polysaccharides without pigment (melanin) were produced by SC of strain NG. Pullulan content of the polysaccharides was very high (98.37%). Fourier-transform infrared spectroscopy confirmed that chemical structures of the polysaccharides and standard pullulan were identical. Swollen cells produced 2.08 mg/ml non-pigmented polysaccharides at 96 h in YPD medium. Controlling pH of fermentation is an effective and convenient method to harvest SC for melanin-free pullulan production.

Extraction of indirectly captured information for use in a comparison of offline pH measurement technologies.

PubMed

Ritchie, Elspeth K; Martin, Elaine B; Racher, Andy; Jaques, Colin

2017-06-10

Understanding the causes of discrepancies in pH readings of a sample can allow more robust pH control strategies to be implemented. It was found that 59.4% of differences between two offline pH measurement technologies for an historical dataset lay outside an expected instrument error range of ±0.02pH. A new variable, Osmo Res , was created using multiple linear regression (MLR) to extract information indirectly captured in the recorded measurements for osmolality. Principal component analysis and time series analysis were used to validate the expansion of the historical dataset with the new variable Osmo Res . MLR was used to identify variables strongly correlated (p<0.05) with differences in pH readings by the two offline pH measurement technologies. These included concentrations of specific chemicals (e.g. glucose) and Osmo Res, indicating culture medium and bolus feed additions as possible causes of discrepancies between the offline pH measurement technologies. Temperature was also identified as statistically significant. It is suggested that this was a result of differences in pH-temperature compensations employed by the pH measurement technologies. In summary, a method for extracting indirectly captured information has been demonstrated, and it has been shown that competing pH measurement technologies were not necessarily interchangeable at the desired level of control (±0.02pH). Copyright © 2017 Elsevier B.V. All rights reserved.

Facilitating Student Understanding of Buffering by an Integration of Mathematics and Chemical Concepts

ERIC Educational Resources Information Center

Curtright, Robert; Emry, Randall; Heaton, Ruth M.; Markwell, John

2004-01-01

We describe a simple undergraduate exercise involving the titration of a weak acid by a strong base using a pH meter and a micropipette. Students then use their data and carry out graphical analyses with a spreadsheet. The analyses involve using mathematical concepts such as first-derivative and semi-log plots and provide an opportunity for…

Opening a Can of Worm(‐like Micelle)s: The Effect of Temperature of Solutions of Functionalized Dipeptides

PubMed Central

Draper, Emily R.; Su, Hao; Brasnett, Christopher; Poole, Robert J.; Rogers, Sarah; Cui, Honggang; Seddon, Annela

2017-01-01

Abstract A simple heat/cool cycle can be used to significantly affect the properties of a solution of a low‐molecular‐weight gelator at high pH. The viscosity and extensional viscosity are increased markedly, leading to materials with very different properties than when the native solution is used. PMID:28653804

Social Media in the Classroom: A Simple yet Complex Hybrid Environment for Students

ERIC Educational Resources Information Center

Casey, Gail

2013-01-01

This article reports on part of the author's PhD action research study. It examines the complexity of features that social media and Web 2.0 offer when combined with face-to-face teaching and learning. Action research was used to help redesign the learning programs of XXX's thirteen Middle Years classes over an eighteen month period. These…