Science.gov

Sample records for ph conductivity alkalinity

  1. Carbon dioxide addition to microbial fuel cell cathodes maintains sustainable catholyte pH and improves anolyte pH, alkalinity, and conductivity.

    PubMed

    Fornero, Jeffrey J; Rosenbaum, Miriam; Cotta, Michael A; Angenent, Largus T

    2010-04-01

    Bioelectrochemical system (BES) pH imbalances develop due to anodic proton-generating oxidation reactions and cathodic hydroxide-ion-generating reduction reactions. Until now, workers added unsustainable buffers to reduce the pH difference between the anode and cathode because the pH imbalance contributes to BES potential losses and, therefore, power losses. Here, we report that adding carbon dioxide (CO(2)) gas to the cathode, which creates a CO(2)/bicarbonate buffered catholyte system, can diminish microbial fuel cell (MFC) pH imbalances in contrast to the CO(2)/carbonate buffered catholyte system by Torres, Lee, and Rittmann [Environ. Sci. Technol. 2008, 42, 8773]. We operated an air-cathode and liquid-cathode MFC side-by-side. For the air-cathode MFC, CO(2) addition resulted in a stable catholyte film pH of 6.61 +/- 0.12 and a 152% increase in steady-state power density. By adding CO(2) to the liquid-cathode system, we sustained a steady catholyte pH (pH = 5.94 +/- 0.02) and a low pH imbalance (DeltapH = 0.65 +/- 0.18) over a 2-week period without external salt buffer addition. By migrating bicarbonate ions from the cathode to the anode (with an anion-exchange membrane), we increased the anolyte pH (DeltapH = 0.39 +/- 0.31), total alkalinity (494 +/- 6 to 582 +/- 6 as mg CaCO(3)/L), and conductivity (1.53 +/- 0.49 to 2.16 +/- 0.03 mS/cm) relative to the feed properties. We also verified with a phosphate-buffered MFC that our reaction rates were limited mainly by the reactor configuration rather than limitations due to the bicarbonate buffer.

  2. Alkaline pH sensor molecules.

    PubMed

    Murayama, Takashi; Maruyama, Ichiro N

    2015-11-01

    Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range.

  3. Carbon Dioxide Addition to Microbial Fuel Cell Cathodes Maintains Sustainable Catholyte pH and Improves Anolyte pH, Alkalinity, and Conductivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bioelectrochemical system (BES) pH imbalances develop due to anodic proton-generating oxidation reactions and cathodic hydroxide-ion-generating reduction reactions. Until now, workers added unsustainable buffers to reduce the pH difference between the anode and cathode because the pH imbalance cont...

  4. Irrigation water acidification to neutralize alkalinity for nursery crop production: Substrate pH, electrical conductivity, and nutrient concentrations; and plant nutrition and growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Liming agents (LA) in irrigation water, typically associated with carbonates and bicarbonates of calcium (Ca) and magnesium (Mg), contribute to water alkalinity. Repeated application of LA to container crops can cause media-solution pH to rise overtime, that uncorrected, can lead to a nutrient avail...

  5. Low pH alkaline chemical formulations

    SciTech Connect

    French, T.R.; Peru, D.A.; Thornton, S.D.

    1989-01-01

    This report describes the development of a surfactant-enhanced alkaline flooding system that is applicable to specific reservoir conditions in Wilmington (California) field. The cost of the chemicals for an ASP (alkali/surfactant/polymer) flood is calculated to be $3.90/bbl of oil produced, with 78% of that cost attributable to polymer. This research included phase behavior tests, oil displacement tests, mineral dissolution tests, and adsorption measurements. It was discovered that consumption of low pH alkalis is low enough in the Wilmington field to be acceptable. In addition, alkali dramatically reduced surfactant adsorption and precipitation. A mixture of NaHCO3 and Na2CO3 was recommended for use as a preflush and in the ASP formulation. Research was also conducted on the synergistic effect that occurs when a mixture of alkali and synthetic surfactant contacts crude oil. It appears that very low IFT is predominantly a result of the activation of the natural surfactants present in the Wilmington oil, and the sustained low IFT is primarily the result of the synthetic surfactant. It also appears that removal of acids from the crude oil by the alkali renders the oil more interfacially reactive to synthetic surfactant. These phenomena help to explain the synergism that results from combining alkali and synthetic surfactant into a single oil recovery formulation. 19 refs., 24 figs., 10 tabs.

  6. Field measurement of alkalinity and pH

    USGS Publications Warehouse

    Barnes, Ivan

    1964-01-01

    The behavior of electrometric pH equipment under field conditions departs from the behavior predicted from Nernst's law. The response is a linear function of pH, and hence measured pH values may be corrected to true pH if the instrument is calibrated with two reference solutions for each measurement. Alkalinity titrations may also be made in terms of true pH. Standard methods, such as colorimetric titrations, were rejected as unreliable or too cumbersome for rapid field use. The true pH of the end point of the alkalinity titration as a function of temperature, ionic strength, and total alkalinity has been calculated. Total alkalinity in potable waters is the most important factor influencing the end point pH, which varies from 5.38 (0 ? C, 5 ppm (parts per million) HC0a-) to 4.32 (300 ppm HC0a-,35 ? C), for the ranges of variables considered. With proper precautions, the pH may be determined to =i:0.02 pH and the alkalinity to =i:0.6 ppm HCO3- for many naturally occurring bodies of fresh water.

  7. The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?

    PubMed Central

    Schwalfenberg, Gerry K.

    2012-01-01

    This review looks at the role of an alkaline diet in health. Pubmed was searched looking for articles on pH, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine. PMID:22013455

  8. The alkaline diet: is there evidence that an alkaline pH diet benefits health?

    PubMed

    Schwalfenberg, Gerry K

    2012-01-01

    This review looks at the role of an alkaline diet in health. Pubmed was searched looking for articles on pH, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine.

  9. Alkaline pH Homeostasis in Bacteria: New Insights

    PubMed Central

    Padan, Etana; Bibi, Eitan; Ito, Masahiro; Krulwich, Terry A.

    2011-01-01

    The capacity of bacteria to survive and grow at alkaline pH values is of widespread importance in the epidemiology of pathogenic bacteria, in remediation and industrial settings, as well as in marine, plant-associated and extremely alkaline ecological niches. Alkali-tolerance and alkaliphily, in turn, strongly depend upon mechanisms for alkaline pH homeostasis, as shown in pH shift experiments and growth experiments in chemostats at different external pH values. Transcriptome and proteome analyses have recently complemented physiological and genetic studies, revealing numerous adaptations that contribute to alkaline pH homeostasis. These include elevated levels of transporters and enzymes that promote proton capture and retention (e.g. the ATP synthase and monovalent cation/proton antiporters), metabolic changes that lead to increased acid production, and changes in the cell surface layers that contribute to cytoplasmic proton retention. Targeted studies over the past decade have followed up the long-recognized importance of monovalent cations in active pH homeostasis. These studies show the centrality of monovalent cation/proton antiporters in this process while microbial genomics provides information about the constellation of such antiporters in individual strains. A comprehensive phylogenetic analysis of both eukaryotic and prokaryotic genome databases has identified orthologes from bacteria to humans that allow better understanding of the specific functions and physiological roles of the antiporters. Detailed information about the properties of multiple antiporters in individual strains is starting to explain how specific monovalent cation/proton antiporters play dominant roles in alkaline pH homeostasis in cells that have several additional antiporters catalyzing ostensibly similar reactions. New insights into the pH-dependent Na+/H+ antiporter NhaA that plays an important role in Escherichia coli have recently emerged from the determination of the structure

  10. Biochemical Stabilization of Glucagon at Alkaline pH

    PubMed Central

    Jackson, Melanie A.; Castle, Jessica R.; El Youssef, Joseph; Bakhtiani, Parkash A.; Bergstrom, Colin P.; Carroll, Julie M.; Breen, Matthew E.; Leonard, Gerald L.; David, Larry L.; Roberts, Charles T.; Ward, W. Kenneth

    2014-01-01

    Abstract Background: For patients with type 1 diabetes mellitus, a bihormonal artificial endocrine pancreas system utilizing glucagon and insulin has been found to stabilize glycemic control. However, commercially available formulations of glucagon cannot currently be used in such systems because of physical instability characterized by aggregation and chemical degradation. Storing glucagon at pH 10 blocks protein aggregation but results in chemical degradation. Reductions in pH minimize chemical degradation, but even small reductions increase protein aggregation. We hypothesized that common pharmaceutical excipients accompanied by a new excipient would inhibit glucagon aggregation at an alkaline pH. Methods and Results: As measured by tryptophan intrinsic fluorescence shift and optical density at 630 nm, protein aggregation was indeed minimized when glucagon was formulated with curcumin and albumin. This formulation also reduced chemical degradation, measured by liquid chromatography with mass spectrometry. Biological activity was retained after aging for 7 days in an in vitro cell-based bioassay and also in Yorkshire swine. Conclusions: Based on these findings, a formulation of glucagon stabilized with curcumin, polysorbate-80, l-methionine, and albumin at alkaline pH in glycine buffer may be suitable for extended use in a portable pump in the setting of a bihormonal artificial endocrine pancreas. PMID:24968220

  11. Interpretation of pH, acidity, and alkalinity in fisheries and aquaculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measurements of pH, acidity, and alkalinity are commonly used to describe water quality. The three variables are interrelated and are sometimes confused. The pH of water is an intensity factor, while the acidity and alkalinity of waters are capacity factors. More precisely, acidity and alkalinity ar...

  12. Decision making in C. elegans chemotaxis to alkaline pH

    PubMed Central

    Murayama, Takashi; Maruyama, Ichi N

    2013-01-01

    Monitoring of environmental and tissue pH is critical for animal survival. The nematode, Caenorhabditis elegans (C. elegans), is attracted to mildly alkaline pH, but avoids strongly alkaline pH. However, little is known about how the behavioral switching or decision making occurs. Genetic dissection and Ca2+ imaging have previously demonstrated that ASEL and ASH are the major sensory neurons responsible for attraction and repulsion, respectively. Here we report that unlike C. elegans wild type, mutants deficient in ASEL or ASH were repelled by mildly alkaline pH, or were attracted to strongly alkaline pH, respectively. These results suggest that signals through ASEL and ASH compete to determine the animal’s alkaline-pH chemotaxis. Furthermore, mutants with 2 ASEL neurons were more efficiently attracted to mildly alkaline pH than the wild type with a single ASEL neuron, indicating that higher activity of ASEL induces stronger attraction to mildly alkaline pH. This stronger attraction was overridden by normal activity of ASH, suggesting that ASH-mediated avoidance dominates ASEL-mediated attraction. Thus, C. elegans chemotactic behaviors to alkaline pH seems to be determined by signal strengths from the sensory neurons ASEL and ASH, and the behavior decision making seems to be the result of competition between the 2 sensory neurons. PMID:24563708

  13. SIMPLE WAYS TO IMPROVE PH AND ALKALINITY MEASUREMENTS FOR WATER UTILITIES AND LABORATORIES

    EPA Science Inventory

    Both pH and total alkalinity determinations are critical in characterizing chemical properties of water, being important to implementing good process control, determining corrosivity and other water quality properties, and assessing changes in water characteristics. Poor charac...

  14. Cementitious porous pavement in stormwater quality control: pH and alkalinity elevation.

    PubMed

    Kuang, Xuheng; Sansalone, John

    2011-01-01

    A certain level of alkalinity acts as a buffer and maintains the pH value in a stable range in water bodies. With rapid urban development, more and more acidic pollutants flow to watersheds with runoff and drop alkalinity to a very low level and ultimately degrade the water environment. Cementitious porous pavement is an effective tool for stormwater acidic neutralization. When stormwater infiltrates cement porous pavement (CPP) materials, alkalinity and pH will be elevated due to the basic characteristics of cement concrete. The elevated alkalinity will neutralize acids in water bodies and maintain the pH in a stable level as a buffer. It is expected that CPP materials still have a certain capability of alkalinity elevation after years of service, which is important for CPP as an effective tool for stormwater management. However, few previous studies have reported on how CPP structures would elevate runoff alkalinity and pH after being exposed to rainfall-runoff for years. In this study, three groups of CPP specimens, all exposed to rainfall-runoff for 3 years, were used to test the pH and alkalinity elevation properties. It was found that runoff pH values were elevated from 7.4 to the range of 7.8-8.6 after infiltrating through the uncoated specimens, and from 7.4 to 8.5-10.7 after infiltrating through aluminum-coated specimens. Runoff alkalinity elevation efficiencies are 11.5-14.5% for uncoated specimens and 42.2% for coated specimens. The study shows that CPP is an effective passive unit operation for stormwater acid neutralization in our built environment.

  15. An alkaline active xylanase: insights into mechanisms of high pH catalytic adaptation.

    PubMed

    Mamo, Gashaw; Thunnissen, Marjolein; Hatti-Kaul, Rajni; Mattiasson, Bo

    2009-09-01

    The alkaliphilic bacterium, Bacillus halodurans S7, produces an alkaline active xylanase (EC 3.2.1.8), which differs from many other xylanases in being operationally stable under alkaline conditions as well as at elevated temperature. Compared to non-alkaline active xylanases, this enzyme has a high percent composition of acidic amino acids which results in high ratio of negatively to positively charged residues. A positive correlation was observed between the charge ratio and the pH optima of xylanases. The recombinant xylanase was crystallized using a hanging drop diffusion method. The crystals belong to the space group P2(1)2(1)2(1) and the structure was determined at a resolution of 2.1 A. The enzyme has the common eight-fold TIM-barrel structure of family 10 xylanases; however, unlike non-alkaline active xylanases, it has a highly negatively charged surface and a deeper active site cleft. Mutational analysis of non-conserved amino acids which are close to the acid/base residue has shown that Val169, Ile170 and Asp171 are important to hydrolyze xylan at high pH. Unlike the wild type xylanase which has optimum pH at 9-9.5, the triple mutant xylanase (V169A, I170F and D171N), which was constructed using sequence information of alkaline sensitive xylanses was optimally active around pH 7. Compared to non-alkaline active xylanases, the alkaline active xylanases have highly acidic surfaces and fewer solvent exposed alkali labile residues. Based on these results obtained from sequence, structural and mutational analysis, the possible mechanisms of high pH stability and catalysis are discussed. This will provide useful information to understand the mechanism of high pH adaptation and engineering of enzymes that can be operationally stable at high pH.

  16. Method of determining pH by the alkaline absorption of carbon dioxide

    DOEpatents

    Hobbs, David T.

    1992-01-01

    A method for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction.

  17. Transient removal of alkaline zones after excitation of Chara cells is associated with inactivation of high conductance in the plasmalemma

    PubMed Central

    2009-01-01

    The action potential (AP) of excitable plant cells is a multifunctional physiological signal. Its generation in characean algae suppresses the pH banding for 15–30 min and enhances the heterogeneity of spatial distribution of photosynthetic activity. This suppression is largely due to the cessation of H+ influx (OH− efflux) in the alkaline cell regions. Measurements of local pH and membrane conductance in individual space-clamped alkaline zones (small cell areas bathed in an isolated pool of external medium) showed that the AP generation is followed by the transient disappearance of alkaline zone in parallel with a large decrease in membrane conductance. These changes, specific to alkaline zones, were only observed under continuous illumination following a relaxation period of at least 15 min after previous excitation. The excitation of dark-adapted cells produced no conductance changes in the post-excitation period. The results indicate that the origin of alkaline zones in characean cells is not due to operation of electroneutral H+/HCO3− symport or OH−/HCO3− antiport. It is concluded that the membrane excitation is associated with inactivation of plasmalemma high conductance in the alkaline cell regions. PMID:19820298

  18. Change of pH during excess sludge fermentation under alkaline, acidic and neutral conditions.

    PubMed

    Yuan, Yue; Peng, Yongzhen; Liu, Ye; Jin, Baodan; Wang, Bo; Wang, Shuying

    2014-12-01

    The change in pH during excess sludge (ES) fermentation of varying sludge concentrations was investigated in a series of reactors at alkaline, acidic, and neutral pHs. The results showed that the changes were significantly affected by fermentative conditions. Under different conditions, pH exhibited changing profiles. When ES was fermented under alkaline conditions, pH decreased in a range of (10±1). At the beginning of alkaline fermentation, pH dropped significantly, at intervals of 4h, 4h, and 5h with sludge concentrations of 8665.6mg/L, 6498.8mg/L, and 4332.5mg/L, then it would become moderate. However, under acidic conditions, pH increased from 4 to 5. Finally, under neutral conditions pH exhibited a decrease then an increase throughout entire fermentation process. Further study showed short-chain fatty acids (SCFAs), ammonia nitrogen and cations contributed to pH change under various fermentation conditions. This study presents a novel strategy based on pH change to predict whether SCFAs reach their stable stage.

  19. Method of determining pH by the alkaline absorption of carbon dioxide

    DOEpatents

    Hobbs, D.T.

    1992-10-06

    A method is described for measuring the concentration of hydroxides in alkaline solutions in a remote location using the tendency of hydroxides to absorb carbon dioxide. The method includes the passing of carbon dioxide over the surface of an alkaline solution in a remote tank before and after measurements of the carbon dioxide solution. A comparison of the measurements yields the absorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to absorption fraction. 2 figs.

  20. Extremely alkaline (pH > 12) ground water hosts diverse microbial community.

    PubMed

    Roadcap, George S; Sanford, Robert A; Jin, Qusheng; Pardinas, José R; Bethke, Craig M

    2006-01-01

    Chemically unusual ground water can provide an environment for novel communities of bacteria to develop. Here, we describe a diverse microbial community that inhabits extremely alkaline (pH > 12) ground water from the Lake Calumet area of Chicago, Illinois, where historic dumping of steel slag has filled in a wetland. Using microbial 16S ribosomal ribonucleic acid gene sequencing and microcosm experiments, we confirmed the presence and growth of a variety of alkaliphilic beta-Proteobacteria, Bacillus, and Clostridium species at pH up to 13.2. Many of the bacterial sequences most closely matched those of other alkaliphiles found in more moderately alkaline water around the world. Oxidation of dihydrogen produced by reaction of water with steel slag is likely a primary energy source to the community. The widespread occurrence of iron-oxidizing bacteria suggests that reduced iron serves as an additional energy source. These results extend upward the known range of pH tolerance for a microbial community by as much as 2 pH units. The community may provide a source of novel microbes and enzymes that can be exploited under alkaline conditions.

  1. Specific molten globule conformation of stem bromelain at alkaline pH.

    PubMed

    Dave, Sandeep; Mahajan, Sahil; Chandra, Vemika; Dkhar, H Kitdorlang; Sambhavi; Gupta, Pawan

    2010-07-01

    Stem bromelain (SBM), a therapeutic protein, is rapidly absorbed across the gut epithelium. Because SBM encounters an alkaline pH at its principal site of absorption, we investigated the alkaline-induced denaturation of SBM. From pH 7 to 10, the protein's secondary structure remained the same, although a slight loss of tertiary structure was observed. Above pH 10, there was a significant and irreversible loss of secondary and tertiary structure. At pH 10, SBM showed enhanced tryptophan fluorescence, however, the number of accessible tryptophans remained the same. The thermodynamics of temperature transition at pH 7 and 10 were strikingly different, with the former showing a two-phase transition endotherm, and the latter a broad non-two-state transition. At pH 10, SBM showed a significant increase in 8-anilino-1-naphthalene-sulfonate binding relative to the native state, suggestive of a specific molten globule (SMG) state. These studies suggest a distinct conformational rearrangement in SBM, at the protein's isoelectric point.

  2. pH measurement of low-conductivity waters

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L.N.

    1987-01-01

    pH is an important and commonly measured parameter of precipitation and other natural waters. The various sources of errors in pH measurement were analyzed and procedures for improving the accuracy and precision of pH measurements in natural waters with conductivities of < 100 uS/cm at 25 C are suggested. Detailed procedures are given for the preparation of dilute sulfuric acid standards to evaluate the performance of pH electrodes in low conductivity waters. A daily check of the pH of dilute sulfuric acid standards and deionized water saturated with a gas mixture of low carbon dioxide at partial pressure (air) prior to the measurement of the pH of low conductivity waters is suggested. (Author 's abstract)

  3. Improved volatile fatty acids anaerobic production from waste activated sludge by pH regulation: Alkaline or neutral pH?

    PubMed

    Ma, Huijun; Chen, Xingchun; Liu, He; Liu, Hongbo; Fu, Bo

    2016-02-01

    In this study, the anaerobic fermentation was carried out for volatile fatty acids (VFAs) production at different pH (between 7.0 and 10.0) conditions with untreated sludge and heat-alkaline pretreated waste activated sludge. In the fermentation with untreated sludge, the extent of hydrolysis of organic matters and extent of acidification at alkaline pH are 54.37% and 30.37%, respectively, resulting in the highest VFAs yield at 235.46mg COD/gVS of three pH conditions. In the fermentation with heat-alkaline pretreated sludge, the acidification rate and VFAs yield at neutral pH are 30.98% and 240.14mg COD/gVS, respectively, which are higher than that at other pH conditions. With the glucose or bovine serum albumin as substrate for VFAs production, the neutral pH showed a higher VFAs concentration than the alkaline pH condition. The results of terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that the alkaline pH caused low microbial richness. Based on the results in this study, we demonstrated that the alkaline pH is favor of hydrolysis of organic matter in sludge while neutral pH improved the acidogenesis for the VFAs production from sludge. Our finding is obvious different to the previous research and helpful for the understanding of how heat-alkaline pretreatment and alkaline fermentation influence the VFAs production, and beneficial to the development of VFAs production process.

  4. Abiotic Synthesis of Methane Under Alkaline Hydrothermal Conditions: the Effect of pH in Heterogeneous Catalysis

    NASA Astrophysics Data System (ADS)

    Foustoukos, D. I.; Qi, F.; Seyfried, W. E.

    2004-12-01

    Abiotic formation of methane in hydrothermal reaction zones at mid-ocean ridges likely occurs by Fischer-Tropsch catalytic processes involving reaction of CO2-bearing fluids with mineral surfaces. The elevated concentrations of dissolved methane and low molecular weight hydrocarbons observed in high temperature vent fluids issuing from ultramafic-hosted hydrothermal systems, in particular, suggest that Fe and Cr-bearing mineral phases attribute as catalysts, enhancing abiotic production of alkanes. The chemi-adsorption of dissolved CO2 on the catalytic mineral surface, however, might be influenced by a pH dependent surface electron charge developed within the mineral-fluid interface. Thus, a series of experiments was conducted to evaluate the role of pH on rates of carbon reduction in fluids coexisting with Fe-oxides at 390 degree C and 400 bars. At two distinct pH conditions, acidic (pH = 5) and alkaline (pH = 8.8), the abiotic production of isotopically labelled CH4(aq) was monitored during FeO reaction with aqueous NaCl-NaHCO3-H2-bearing fluid (0.56 mol/kg NaCl, 0.03 mol/kg NaH13CO3). Despite the lower H2(aq) concentrations (120 mmol/kg) in the high pH system, concentrations of abiogenic methane attained values of 195 umol/kg and 120 umol/kg respectively, suggesting enhanced catalytic properties of mineral under moderately high pH. X-ray photoelectron spectroscopy (XPS), performed on unreacted and final solid products, reveal the significantly greater abundances of alkyl (C-C-) groups on the surface of FeO oxidized at elevated pH, in comparison with mineral reacted at low pH conditions. Thus, enhanced adsorption of dissolved CO2 and the resulting Fischer-Tropsch formation of alkyl groups likely contributes to methane production observed at alkaline conditions. Introducing the effect of pH in the Fischer-Tropsch mechanism of alkane formation has important implications for the recently discovered Lost City ultramafic-hosted hydrothermal system, where elevated pH

  5. Design of stability at extreme alkaline pH in streptococcal protein G.

    PubMed

    Palmer, Benjamin; Angus, Katy; Taylor, Linda; Warwicker, Jim; Derrick, Jeremy P

    2008-04-30

    Protein G (PrtG) is widely used as an affinity-based ligand for the purification of IgG. It would be desirable to improve the resistance of affinity chromatography ligands, such as PrtG, to commercial cleaning-in-place procedures using caustic alkali (0.5 M NaOH). It has been shown that Asn residues are the most susceptible at extreme alkaline pH: here, we show that replacement of all three Asn residues within the IgG-binding domain of PrtG only improves stability towards caustic alkali by about 8-fold. Study of the effects of increasing pH on PrtG by fluorescence and CD shows that the protein unfolds progressively between pH 11.5 and 13.0. Calculation of the variation in electrostatic free energy with pH indicated that deprotonation of Tyr, Lys and Arg side-chains at high pH would destabilize PrtG. Introduction of the triple mutation Y3F/T16I/T18I into PrtG stabilized it by an extra 6.8 kcal/mol and the unfolding of the protein occurred at a pH of about 13, or 1.5 pH units higher than wild type. The results show that strategies for the stabilization of proteins at extreme alkaline pH should consider thermodynamic stabilization that will retain the tertiary structure of the protein and modification of surface electrostatics, as well as mutation of alkali-susceptible residues.

  6. The Effects of Alkaline pH on Microleakage of Mineral Trioxide Aggregate and Calcium Enriched Mixture Apical Plugs

    PubMed Central

    Mirhadi, Hossein; Moazzami, Fariborz; Rangani Jahromi, Saeed; Safarzade, Sareh

    2016-01-01

    Statement of the Problem Alkaline pH can affect the physical and chemical properties and sealing ability of apical plug material. Calcium hydroxide is used as an intracanal medication to complete disinfection of root canals. It raises the pH of environment to alkaline value. Purpose The aim of this in vitro study was to evaluate and compare the effect of alkaline pH on the sealing ability of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA) apical plugs. Materials and Method Seventy single-rooted human maxillary anterior teeth were randomly divided to two experimental groups for Angelus MTA and CEM cement (n=30) and two control groups (n=5). Each group was divided into two subgroups of 15 for neutral and alkaline pH, and 1 negative and 1 positive control groups of 5. The root canals were cleaned and shaped by using ProTaper rotary system (Dentsply Maillefer; Ballaigues, Switzerland) and the terminal 3mm of the roots were resected. Then, MTA and CEM cement were condensed in apical region with 3mm thickness. The samples were exposed to two environments with different pH values of 13 and 7.4. The leakage was assessed by using the fluid filtration technique at 1, 7, 14, 30 days intervals. Data were analyzed by the repeated measures MANOVA. Results There was no statistically significant difference in the rate of microleakage between neutral and alkaline pH of CEM cement and MTA (p> 0.05). The sealing ability of MTA in an alkaline pH of 13 was significantly less than CEM cement in this pH (p< 0.05). Conclusion An environment with alkaline pH had no adverse effect on the sealing ability of MTA and CEM cement used as apical plugs. CEM cement had better sealing ability in alkaline pH. PMID:26966703

  7. pH neutralization and zonation in alkaline-saline tank waste plumes.

    PubMed

    Wan, Jiamin; Larsen, Joern T; Tokunaga, Tetsu K; Zheng, Zuoping

    2004-03-01

    At the Hanford Site in Washington State, the pH values of contaminant plumes resulting from leaking of initially highly alkaline-saline radioactive waste solutions into the subsurface are now found to be substantially neutralized. However, the nature of plume pH neutralization has not previously been understood. As a master geochemical variable, pH needs to be understood in order to predict the fate and transport of contaminants carried by the waste plumes. Through this laboratory study, we found that the plume pH values spanned a broad range from 14 (within the near-source region) down to the value of 7 (lower than the pH value of the initial soil solution) while the plume was still connected to an actively leaking source. We defined two zones within a plume: the silicate dissolution zone (SDZ, pH 14-10) and the neutralized zone (NZ, pH 10-7). Quartz dissolution at elevated temperature and precipitation of secondary silicates (including sodium metasilicate, cancrinite, and zeolites) are the key reactions responsible for the pH neutralization within the SDZ. The rapid and thorough cation exchange of Na+ replacing Ca2+/Mg2+, combined with transport, resulted in a dynamic Ca2+/Mg2+-enriched plume front. Subsequent precipitation of calcite, sodium silicate, and possibly talc led to dramatically reduced pH within the plume front and the neutralized zone. During aging (after the plume source became inactive), continued quartz dissolution and the secondary silicate precipitation drove the pH value lower, toward pH 11 at equilibrium within the SDZ, whereas the pH values in the NZ remained relatively unchanged with time. A pH profile of 11 from the plume source to pH 7 at the plume front is expected for a historical plume. This laboratory-based study provided realistic plume pH profiles (consistent with that measured from borehole samples) and identified underlying mechanisms responsible for pH evolution.

  8. Anoxic Biodegradation of Isosaccharinic Acids at Alkaline pH by Natural Microbial Communities

    PubMed Central

    Rout, Simon P.; Charles, Christopher J.; Doulgeris, Charalampos; McCarthy, Alan J.; Rooks, Dave J.; Loughnane, J. Paul; Laws, Andrew P.; Humphreys, Paul N.

    2015-01-01

    One design concept for the long-term management of the UK’s intermediate level radioactive wastes (ILW) is disposal to a cementitious geological disposal facility (GDF). Under the alkaline (10.0<pH>13.0) anoxic conditions expected within a GDF, cellulosic wastes will undergo chemical hydrolysis. The resulting cellulose degradation products (CDP) are dominated by α- and β-isosaccharinic acids (ISA), which present an organic carbon source that may enable subsequent microbial colonisation of a GDF. Microcosms established from neutral, near-surface sediments demonstrated complete ISA degradation under methanogenic conditions up to pH 10.0. Degradation decreased as pH increased, with β-ISA fermentation more heavily influenced than α-ISA. This reduction in degradation rate was accompanied by a shift in microbial population away from organisms related to Clostridium sporosphaeroides to a more diverse Clostridial community. The increase in pH to 10.0 saw an increase in detection of Alcaligenes aquatilis and a dominance of hydrogenotrophic methanogens within the Archaeal population. Methane was generated up to pH 10.0 with acetate accumulation at higher pH values reflecting a reduced detection of acetoclastic methanogens. An increase in pH to 11.0 resulted in the accumulation of ISA, the absence of methanogenesis and the loss of biomass from the system. This study is the first to demonstrate methanogenesis from ISA by near surface microbial communities not previously exposed to these compounds up to and including pH 10.0. PMID:26367005

  9. Transcriptome Profiling of Shewanella oneidensis Gene Expressionfollowing Exposure to Acidic and Alkaline pH

    SciTech Connect

    Leaphart, Adam B.; Thompson, Dorothea K.; Huang, Katherine; Alm,Eric; Wan, Xiu-Feng; Arkin, Adam P.; Brown, Steven D.; Wu, Liyou; Yan,Tingfen; Liu, Xueduan; Wickham, Gene S.; Zhou, Jizhong

    2007-04-02

    The molecular response of Shewanella oneidensis MR-1 tovariations in extracellular pH was investigated based on genomewide geneexpression profiling. Microarray analysis revealed that cells elicitedboth general and specific transcriptome responses when challenged withenvironmental acid (pH 4) or base (pH 10) conditions over a 60-minperiod. Global responses included the differential expression of genesfunctionally linked to amino acid metabolism, transcriptional regulationand signal transduction, transport, cell membrane structure, andoxidative stress protection. Response to acid stress included theelevated expression of genes encoding glycogen biosynthetic enzymes,phosphate transporters, and the RNA polymerase sigma-38 factor (rpoS),whereas the molecular response to alkaline pH was characterized byupregulation of nhaA and nhaR, which are predicted to encode an Na+/H+antiporter and transcriptional activator, respectively, as well assulfate transport and sulfur metabolism genes. Collectively, theseresults suggest that S. oneidensis modulates multiple transporters, cellenvelope components, and pathways of amino acid consumption and centralintermediary metabolism as part of its transcriptome response to changingexternal pH conditions.

  10. Predicting Carbonate Species Ionic Conductivity in Alkaline Anion Exchange Membranes

    DTIC Science & Technology

    2012-06-01

    anion exchange membranes. Andrew M. Kiss, Timothy D . Myles, Kyle N. Grew, Aldo A. Peracchio, George J. Nelson, and Wilson K. S. Chiu University of...Alkaline Anion Exchange Membranes Andrew M. Kiss1, Timothy D . Myles1, Kyle N. Grew2, Aldo A. Peracchio1, George J. Nelson1, and Wilson K. S. Chiu1* 1...Vol. 301, 93-106, 2007. 16. Satterfleld,M.B., Benziger,J.B., J. Phys. Chem. B, Vol. 112,12, 3693 -3704, 2008. 17. Motupally,S., Becker,A.J

  11. Use of natural mordenite to remove chromium (III) and to neutralize pH of alkaline waste waters.

    PubMed

    Córdova-Rodríguez, Valduvina; Rodríguez-Iznaga, Inocente; Acosta-Chávez, Raquel María; Chávez-Rivas, Fernando; Petranovskii, Vitalii; Pestryakov, Alexey

    2016-01-01

    The natural mordenite from Palmarito de Cauto deposit (PZ), Cuba, was studied in this work as an ion exchanger to remove Cr(3+) cations from alkaline aqueous solutions at different pH and chromium concentrations. The mordenite stability under cyclic treatment processes with alkaline solutions and its capacity to decrease the pH of the solutions was also analyzed. It was shown that PZ removes Cr(3+) ions from alkaline solutions, and it happens independently of the starting chromium concentration and the pH of the exchange solution used. This material has an important neutralizing effect on alkaline solutions, expressed in a significant pH decrease from the early stages of the treatments. For solutions with initial pH equal to 11, it decreases to a value of around seven. The stability of this material is not affected significantly after continuous cyclic treatment with NaOH solution, which shows that mordenite, in particular from Palmarito de Cauto deposit, has high stability in alkaline solutions. The results are important as they suggest that natural zeolites may be of interest in treatments of alkaline industrial waste effluents.

  12. Uranium(VI) Diffusion in Sodium-Montmorillonite at Alkaline pH Conditions

    NASA Astrophysics Data System (ADS)

    Tinnacher, R. M.; Davis, J. A.; Tournassat, C.; Birkholzer, J. T.

    2015-12-01

    Diffusive transport of uranium(VI) in montmorillonite clay and bentonite has important implications for uranium(VI) mobility in engineered barrier systems or host rocks in high level radioactive waste repositories, and clay-rich soils and sediments in the environment. The prediction of uranium(VI) adsorption and diffusion in clay-rich media, however, is complicated by (1) the complexity of the mineralogical structure of montmorillonite, in terms of its pore-size distributions and available surface site types, and (2) the complex uranium(VI) solution speciation, which can include cationic, uncharged, and anionic complexes, depending on solution conditions. For instance, a partial or full exclusion of anions from negatively charged clay interlayer spaces could change the effective 'anion-accessible' porosity and decrease the diffusive flux of these solutes under steady state conditions. In contrast, weak cation exchange reactions can result in 'surface diffusion' of adsorbed cations, such as UO2OH+, in addition to diffusion in the liquid phase, resulting in greater diffusive fluxes at steady state. In order to investigate these complex interactions, we performed two, lab-scale uranium(VI) through-diffusion experiments in lightly compacted Na-montmorillonite at slightly different, alkaline pH conditions (average pH values of 8.69 and 8.87). Observed uranium(VI) diffusive fluxes were decreased by approximately an order of magnitude in comparison to a tritium tracer. This indicates a relevance of 'anion exclusion' effects, the full or partial exclusion of anionic U(VI)-carbonato species from clay interlayer spaces. In addition, uranium(VI) sorption reactions were shown to be relevant in the diffusion experiments, even at alkaline pH values of around 8.7 and 8.9, where uranium(VI) sorption is low compared to other pH conditions. Despite the similarity of pH conditions, different degrees of uranium(VI) retardation were determined for the two systems. Additionally, we

  13. Improved methane production from waste activated sludge with low organic content by alkaline pretreatment at pH 10.

    PubMed

    Feng, L Y; Yang, L Q; Zhang, L X; Chen, H L; Chen, J

    2013-01-01

    Sludge with low organic content always results in an unsatisfactory performance, even failure of anaerobic digestion. The alkaline pretreatment effect on anaerobic digestion of sludge with low organic content has seldom been studied although it gives many benefits for sludge with high organic content. In this study the influence of alkaline pretreatment (pH 10, an effective alkaline pH) on the solubilization and methane production from waste activated sludge (WAS) with low organic content was investigated. Results from biochemical methane potential (BMP) experiments showed that anaerobic biodegradability of WAS was greatly improved by alkaline pretreatment at pH 10. Methane production from the current WAS under conditions of pretreatment time 4 h and digestion time 15 d was 139.6 mL/g VS (volatile solids), much higher than that from the unpretreated WAS with digestion time of 20 d (75.2 mL/g VS). Also, the solubilization of WAS was significantly accelerated by alkaline pretreatment. Mechanism exploration indicated that the general activities of anaerobic microorganisms, specific activities of key enzymes and the amounts of methanogens were enhanced by alkaline pretreatment at pH 10, showing good agreement with methane production.

  14. Low temperature alkaline pH hydrolysis of oxygen-free Titan tholins

    NASA Astrophysics Data System (ADS)

    Brassé, C.; Buch, A.; Raulin, F.; Coll, P.; Poch, O.; Ramirez, S.

    2013-09-01

    Titan, the largest moon of Saturn, is known for its dense and nitrogen-rich atmosphere. The organic aerosols which are produced in Titan's atmosphere are objects of astrobiological interest. In this paper we focus on their potential chemical evolution when they reach the surface and interact with putative ammonia-water cryomagma[1]. In this context we have studied the evolution of alkaline pH hydrolysis of Titan tholins (produced by an experimental setup using a plasma DC discharge named PLASMA) at ambient and low temperature. However, we identified oxygenated molecules in non-hydrolyzed tholins meaning that oxygen gets in the PLASMA reactor during the tholins synthesis [2]. Following this preliminary study the synthesis protocol has been improved by isolating the whole device in a specially designed glove box which protect the PLASMA experiment from the laboratory atmosphere. After confirming the non-presence of oxygen in tholins produced with this new experimental setup, the study of oxygen-free tholins' evolution has been carried out. A recent study shows that the subsurface ocean may contain a lower fraction of ammonia (about 5wt% or less [3]), as previously described by other teams [2,4]. Thus new hydrolysis experiments will take this lower value into account. Additionally, a new report [5] provides upper and lower limits for the bulk content of Titan's interior for various gas species. It also shows that most of them are likely stored and dissolved in the subsurface water ocean. But considering the plausible acido-alkaline properties of the ammonia-water ocean, additional species could be dissolved in the ocean and present in the magma. They were also included in our hydrolysis experiments. Taking into account these new data, four different hydrolysis have been applied to oxygen-free tholins. For each type of hydrolysis, we also follow the influence of the hydrolysis temperature on the organic molecules production. The preliminary qualitative and quantitative

  15. Effect of pH alkaline salts of fatty acids on the inhibition of bacteria associated with poultry processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The agar diffusion assay was used to examine the effect of pH on the ability of alkaline salts of three fatty acids (FA) to inhibit growth of bacteria associated with poultry processing. FA solutions were prepared by dissolving 0.5 M concentrations of caprylic, capric, or lauric acid in separate ali...

  16. Low temperature alkaline pH hydrolysis of oxygen-free Titan tholins

    NASA Astrophysics Data System (ADS)

    Brassé, Coralie; Buch, Arnaud; Raulin, François; Coll, Patrice; Poch, Olivier; Ramirez, Sandra

    2014-05-01

    The largest moon of Saturn, Titan, is known for its dense, nitrogen-rich atmosphere. The organic aerosols which are produced in Titan's atmosphere are of great astrobiological interest, particularly because of their potential evolution when they reach the surface and may interact with putative ammonia-water cryomagma[1]. In this context we have followed the evolution of alkaline pH hydrolysis (25wt% ammonia-water) of Titan tholins (produced by an experimental setup using a plasma DC discharge named PLASMA) at low temperature. Urea has been identified as one of the main product of tholins hydrolysis along with several amino acids (alanine, glycine and aspartic acid). However, those molecules have also been detected in non-hydrolyzed tholins. One explanation is a possible oxygen leak in the PLASMA reactor during the tholins synthesis[2]. Following this preliminary study the synthesis protocol has been improved by isolating the whole device in a specially designed glove box which protect the PLASMA experiment from the laboratory atmosphere. Once we confirmed the non-presence of oxygen in tholins, we performed alkaline pH hydrolysis of oxygen-free tholins. Then we verify that the organic compounds cited above are still produced in-situ. Moreover, a recent study shows that the subsurface ocean may contain a lower fraction of ammonia (about 5wt% or less[3]), than the one used until now in this kind of experimental study[2, 4]. Thus, we have carried out new hydrolysis experiments which take this lower value into account. Additional studies have provided new highlights on the bulk composition of Titan for various gas species. Indeed, the observed Saturn's atmosphere enrichment constrains the composition of the planetesimals present in the feeding zone of Saturn. The enrichment in volatiles in Saturn's atmosphere has been reproduced by assuming the presence of specific gas species[5, 6], in particular CO2 and H2S. In the present study we assume that those gas species have

  17. Quaternary structure of partially liganded intermediates of sheep carbon monoxide hemoglobin at alkaline pH.

    PubMed

    Gray, R D

    1975-01-25

    A rapid change in absorbance was observed in the Soret region during the interval between photolysis of sheep carbon monoxide hemoglobin and the subsequent reassociation of CO in the dark. The rate constant for this spectral change was about 4000 s--1 at 20 degrees in 0.05 M solium borate, pH 9.3. The wavelength dependence of the amplitude of the absorbance change is similar to that observed when deoxygenated alpha and theta chains are allowed to recombine (Brunori, M., Antonini, E., Wyman, J., and Anderson, S. R. (1968) J. Mol. Biol. 34, 357-359), and therefore reflects changes in the quanternary structure of the hemoglobin tetramer induced by ligand displacement. The amplitude of this conformation-dependent spectral change was not a linear function of the fraction of bound CO removed by photolysis. The results suggest that of the possible intermediate species present after partial photolysis, only Hb4 and Hb4(CO) change from the ligand-bound to the ligand-free sturcture prior to CO reassociation under these alkaline conditions.

  18. Modeling the effect of membrane conductivity on the performance of alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Raya, Isaac P.; Ellis, Michael W.; Hernandez-Guerrero, Abel; Elizalde-Blancas, Francisco

    2016-03-01

    The present work proposes and demonstrates a methodology to capture the effect of operating conditions on ionic conductivity of membranes immersed in alkaline media. Based on reported experimental results for an anion exchange membrane (A-201 by Tokuyama) and a cation exchange membrane (Nafion 211), two novel expressions are developed for the ionic conductivity by incorporating the effects of solution concentration and temperature. The expression for the cationic conductivity is applied in a cell-level model to predict the performance of an alkaline direct borohydride fuel cell; it is found that the membrane ionic conductivity significantly affects the cell performance and capturing its functionality is essential to accurately predict the fuel cell performance.

  19. Sewage sludge pretreatment by microwave irradiation combined with activated carbon fibre at alkaline pH for anaerobic digestion.

    PubMed

    Sun, Dedong; Guo, Sixiao; Ma, Nina; Wang, Guowen; Ma, Chun; Hao, Jun; Xue, Mang; Zhang, Xinxin

    2016-01-01

    This research focuses on the effects of microwave-assisted activated carbon fibre (ACF) (MW-ACF) treatment on sewage sludge at alkaline pH. The disintegration and biodegradability of sewage sludge were studied. It was found that the MW-ACF process at alkaline pH provided a rapid and efficient process to disrupt the microbial cells in the sludge. The results suggested that when irradiated at 800 W MW for 110 s with a dose of 1.0 g ACF/g solid concentration (SS) at pH 10.5, the MW-ACF pretreatment achieved 55% SS disintegration, 23% greater than the value of MW alone (32%). The concentration of total nitrogen, total phosphorus, supernatant soluble chemical oxygen demand, protein, and polysaccharide increased by 60%, 144%, 145%, 74%, and 77%, respectively. An increase in biogas production by 63.7% was achieved after 20 days of anaerobic digestion (AD), compared to the control. The results indicated that the MW-ACF pretreatment process at alkaline pH provides novel sludge management options in disintegration of sewage sludge for further AD.

  20. Highly Stable, Anion Conductive, Comb-Shaped Copolymers for Alkaline Fuel Cells

    SciTech Connect

    Li, NW; Leng, YJ; Hickner, MA; Wang, CY

    2013-07-10

    To produce an anion-conductive and durable polymer electrolyte for alkaline fuel cell applications, a series of quaternized poly(2,6-dimethyl phenylene oxide)s containing long alkyl side chains pendant to the nitrogen-centered cation were synthesized using a Menshutkin reaction to form comb-shaped structures. The pendant alkyl chains were responsible for the development of highly conductive ionic domains, as confirmed by small-angle X-ray scattering (SAXS). The comb-shaped polymers having one alkyl side chain showed higher hydroxide conductivities than those with benzyltrimethyl ammonium moieties or structures with more than one alkyl side chain per cationic site. The highest conductivity was observed for comb-shaped polymers with benzyldimethylhexadecyl ammonium cations. The chemical stabilities of the comb-shaped membranes were evaluated under severe, accelerated-aging conditions, and degradation was observed by measuring IEC and ion conductivity changes during aging. The comb-shaped membranes retained their high ion conductivity in 1 M NaOH at 80 degrees C for 2000 h. These cationic polymers were employed as ionomers in catalyst layers for alkaline fuel cells. The results indicated that the C-16 alkyl side chain ionomer had a slightly better initial performance, despite its low IEC value, but very poor durability in the fuel cell. In contrast, 90% of the initial performance was retained for the alkaline fuel cell with electrodes containing the C-6 side chain after 60 h of fuel cell operation.

  1. Evaluation of pH, alkalinity and temperature during air stripping process for ammonia removal from landfill leachate.

    PubMed

    Campos, Juacyara Carbonelli; Moura, Denise; Costa, Ana Paula; Yokoyama, Lidia; Araujo, Fabiana Valeria da Fonseca; Cammarota, Magali Christe; Cardillo, Luigi

    2013-01-01

    The objective of this research was to evaluate the air stripping technology for the removal of ammonia from landfill leachates. In this process, pH, temperature, airflow rate and operation time were investigated. Furthermore, the relationship between the leachate alkalinity and the ammonia removal efficiency during the process was studied. The leachate used in the tests was generated in the Gramacho Municipal Solid Waste Landfill (Rio de Janeiro State, Brazil). The best results were obtained with a temperature of 60(o)C, and they were independent of the pH value for 7 h of operation (the ammonia nitrogen removal was greater than 95%). A strong influence of the leachate alkalinity on the ammonia nitrogen removal was observed; as the alkalinity decreased, the ammonia concentration also decreased because of prior CO2 removal, which increased the pH and consequently favored the NH3 stripping. The air flow rate, in the values evaluated (73, 96 and 120 L air.h(-1).L(-1) of leachate), did not influence the results.

  2. Upper ocean carbon cycling inferred from direct pH observations made by profiling floats and estimated alkalinity

    NASA Astrophysics Data System (ADS)

    Johnson, K. S.; Plant, J. N.; Jannasch, H. W.; Coletti, L. J.; Elrod, V.; Sakamoto, C.; Riser, S.

    2015-12-01

    The annual cycle of dissolved inorganic carbon (DIC) is a key tracer of net community production and carbon export in the upper ocean. In particular, the DIC concentration is much less sensitive to air-sea gas exchange, when compared to oxygen, another key tracer of upper ocean metabolism. However, the annual DIC cycle is observed with a seasonal resolution at only a few time-series stations in the open ocean. Here, we consider the annual carbon cycle that has been observed using profiling floats equipped with pH sensors. Deep-Sea DuraFET pH sensors have been deployed on profiling floats for over three years and they can provide temporal and spatial resolution of 5 to 10 days and 5 to 10 m in the upper ocean over multi-year periods. In addition to pH, a second carbon system parameter is required to compute DIC. Total alkalinity can be derived from the float observations of temperature, salinity and oxygen using equations in these variables that are fitted to shipboard observations of alkalinity obtained in the global repeat hydrography programs (e.g., Juranek et al., GRL, doi:10.1029/2011GL048580, 2011), as the relationships should be stable in time in the open ocean. Profiling floats with pH have been deployed from Hawaii Ocean Time-series (HOT) cruises since late 2012 and an array of floats with pH have been deployed since early 2014 in the Southern Ocean as part of the SOCCOM program. The SOCCOM array should grow to nearly 200 floats over the next 5 years. The sensor data was quality controlled and adjusted by comparing observations at 1500 m depth to the deep climatology of pH (derived from DIC and alkalinity) computed with the GLODAP data set. After adjustment, the surface DIC concentrations were calculated from pH and alkalinity. This yields a data set that is used to examine annual net community production in the oligotrophic North Pacific and in the South Pacific near 150 West from 40 South to 65 South.

  3. The immobilization of all spermatozoa in vitro by bitter lemon drink and the effect of alkaline pH.

    PubMed

    Nwoha, P U

    1992-12-01

    Researchers at Obafemi Awolowo University in Ile-Ife, Nigeria, collected semen samples from 7 healthy men 25-30 years old who had abstained from sex for at least 5 days in order to examine the spermicidal action of 4 soft drinks (Krest bitter lemon, Afri-Cola, Coca-Cola, and Pepsi-Cola), the effect of increased temperature of the drinks on spermicidal action, and the effect of changing the soft drinks from an acid, as it comes from the factory, (ph 2.4) to an alkaline (pH 7.5). Increasing the temperature of the soft drinks from room temperature (22 degrees Celsius) to body temperatures (37 degrees Celsius) did not significantly change the spermicidal action any of the soft drinks. All soft drinks with an acid pH, except Coca-Cola, had a significantly lower percent of sperm motility than those with an alkaline pH (0-42.3% vs. 20-52.1%; p .001). In fact, Krest bitter lemon in its factory form (acid pH) completely immobilized all spermatozoa within 1 minute after the researchers diluted the semen with the soft drink. Alkaline Coca-Cola had a significantly lower percent of sperm motility than did acid Coca-Cola (35.8% vs. 46.5%; p .001). Other than Krest bitter lemon, the significant decreases in sperm motility were not enough to prevent pregnancy. These findings indicated that researchers should test Krest bitter lemon for effectiveness as a postcoital contraceptive. If indeed it proves effective, it has great potential as such a contraceptive among the poor in the densely population developed countries since it is readily available and inexpensive.

  4. Improvement of the optimum pH of Aspergillus niger xylanase towards an alkaline pH by site-directed mutagenesis.

    PubMed

    Li, Fei; Xie, Jingcong; Zhang, Xuesong; Zhao, Linguo

    2015-01-01

    In an attempt to shift the optimal pH of the xylanase B (XynB) from Aspergillus niger towards alkalinity, target mutation sites were selected by alignment between Aspergillus niger xylanase B and other xylanases that have alkalophilic pH optima that highlight charged residues in the eight-residues-longer loop in the alkalophilic xylanase. Multiple engineered XynB mutants were created by site-directed mutagenesis with substitutions Q164K and Q164K+D117N. The variant XynB-117 had the highest optimum pH (at 5.5), which corresponded to a basic 0.5 pH unit shift when compared with the wild-type enzyme. However, the optimal pH of the XynB- 164 mutation was not changed, similar to the wild type. These results suggest that the residues at positions 164 and 117 in the eight-residues-longer loop and the cleft's edge are important in determining the pH optima of XynB from Aspergillus niger.

  5. Computational Design of a pH Stable Enzyme: Understanding Molecular Mechanism of Penicillin Acylase's Adaptation to Alkaline Conditions

    PubMed Central

    Suplatov, Dmitry; Panin, Nikolay; Kirilin, Evgeny; Shcherbakova, Tatyana; Kudryavtsev, Pavel; Švedas, Vytas

    2014-01-01

    Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties. PMID:24959852

  6. Computational design of a pH stable enzyme: understanding molecular mechanism of penicillin acylase's adaptation to alkaline conditions.

    PubMed

    Suplatov, Dmitry; Panin, Nikolay; Kirilin, Evgeny; Shcherbakova, Tatyana; Kudryavtsev, Pavel; Svedas, Vytas

    2014-01-01

    Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties.

  7. Tendency for oxidation of annelid hemoglobin at alkaline pH and dissociated states probed by redox titration.

    PubMed

    Bispo, Jose Ailton Conceicao; Landini, Gustavo Fraga; Santos, Jose Luis Rocha; Norberto, Douglas Ricardo; Bonafe, Carlos Francisco Sampaio

    2005-08-01

    The redox titration of extracellular hemoglobin of Glossoscolex paulistus (Annelidea) was investigated in different pH conditions and after dissociation induced by pressure. Oxidation increased with increasing pH, as shown by the reduced amount of ferricyanide necessary for the oxidation of hemoglobin. This behavior was the opposite of that of vertebrate hemoglobins. The potential of half oxidation (E1/2) changed from -65.3 to +146.8 mV when the pH increased from 4.50 to 8.75. The functional properties indicated a reduction in the log P50 from 1.28 to 0.28 in this pH range. The dissociation at alkaline pH or induced by high pressure, confirmed by HPLC gel filtration, suggested that disassembly of the hemoglobin could be involved in the increased potential for oxidation. These results suggest that the high stability and prolonged lifetime common to invertebrate hemoglobins is related to their low tendency to oxidize at acidic pH, in contrast to vertebrate hemoglobins.

  8. Metabolic flux modeling of detoxification of acetic acid by Ralstonia eutropha at slightly alkaline pH levels.

    PubMed

    Yu, J; Wang, J

    2001-06-20

    Ralstonia eutropha grows on and produces polyhydroxyalkanoates (PHAs) from fermentation acids. Acetic acid, one major organic acid from acidogenesis of organic wastes, has an inhibitory effect on the bacterium at slightly alkaline pH (6 g HAc/L at pH 8). The tolerance of R. eutropha to acetate, however, was increased significantly up to 15 g/L at the slightly alkaline pH level with high cell mass concentration. A metabolic cell model with five fluxes is proposed to depict the detoxification mechanism including mass transfer and acetyl-CoA formation of acetic acid and the formation of three final metabolic products, polyhydroxybutyrate (PHB), active biomass, and CO(2). The fluxes were measured under different conditions such as cell mass concentration, acetic acid concentration, and medium composition. The experimental results indicate that the acetate detoxification by high cell mass concentration is attributed to the increased fluxes at high extracellular acetate concentrations. The fluxes could be doubled to reduce and hence detoxify the accumulated intracellular acetate anions.

  9. Towards high conductivity in anion-exchange membranes for alkaline fuel cells.

    PubMed

    Li, Nanwen; Guiver, Michael D; Binder, Wolfgang H

    2013-08-01

    Quaternized poly(2,6-dimethylphenylene oxide) materials (PPOs) containing clicked 1,2,3-triazoles were first prepared through Cu(I) -catalyzed "click chemistry" to improve the anion transport in anion-exchange membranes (AEMs). Clicked 1,2,3-triazoles incorporated into AEMs provided more sites to form efficient and continuous hydrogen-bond networks between the water/hydroxide and the triazole for anion transport. Higher water uptake was observed for these triazole membranes. Thus, the membranes showed an impressive enhancement of the hydroxide diffusion coefficient and, therefore, the anion conductivities. The recorded hydroxide conductivity was 27.8-62 mS cm(-1) at 20 °C in water, which was several times higher than that of a typical PPO-based AEM (TMA-20) derived from trimethylamine (5 mS cm(-1) ). Even at reduced relative humidity, the clicked membrane showed superior conductivity to a trimethylamine-based membrane. Moreover, similar alkaline stabilities at 80 °C in 1 M NaOH were observed for the clicked and non-clicked membranes. The performance of a H2 /O2 single cell assembled with a clicked AEM was much improved compared to that of a non-clicked TMA-20 membrane. The peak power density achieved for an alkaline fuel cell with the synthesized membrane 1a(20) was 188.7 mW cm(-2) at 50 °C. These results indicated that clicked AEM could be a viable strategy for improving the performance of alkaline fuel cells.

  10. Coordinate responses to alkaline pH stress in budding yeast

    PubMed Central

    Serra-Cardona, Albert; Canadell, David; Ariño, Joaquín

    2015-01-01

    Alkalinization of the medium represents a stress condition for the budding yeast Saccharomyces cerevisiae to which this organism responds with profound remodeling of gene expression. This is the result of the modulation of a substantial number of signaling pathways whose participation in the alkaline response has been elucidated within the last ten years. These regulatory inputs involve not only the conserved Rim101/PacC pathway, but also the calcium-activated phosphatase calcineurin, the Wsc1-Pkc1-Slt2 MAP kinase, the Snf1 and PKA kinases and oxidative stress-response pathways. The uptake of many nutrients is perturbed by alkalinization of the environment and, consequently, an impact on phosphate, iron/copper and glucose homeostatic mechanisms can also be observed. The analysis of available data highlights cases in which diverse signaling pathways are integrated in the gene promoter to shape the appropriate response pattern. Thus, the expression of different genes sharing the same signaling network can be coordinated, allowing functional coupling of their gene products. PMID:28357292

  11. Contrasting pH buffering patterns in neutral-alkaline soils along a 3600 km transect in northern China

    NASA Astrophysics Data System (ADS)

    Luo, W.; Nelson, P. N.; Li, M.-H.; Cai, J.; Zhang, Y.; Zhang, Y.; Shan, Y.; Wang, R.; Han, X.; Jiang, Y.

    2015-08-01

    Soil pH buffering capacity (pHBC) plays a crucial role in predicting acidification rates, yet its large-scale patterns and controls are poorly understood, especially for neutral-alkaline soils. Here, we evaluated the spatial patterns and drivers of pHBC along a 3600 km long transect (1900 km sub-transect with carbonate containing soils and 1700 km sub-transect with non-carbonate containing soils) across northern China. Soil pHBC was greater in the carbonate containing soils than in the non-carbonate containing soils. Acid addition decreased soil pH in the non-carbonate containing soils more markedly than in the carbonate containing soils. Within the carbonate soil sub-transect, soil pHBC was positively correlated with cation exchange capacity (CEC), carbonate content and exchangeable sodium (Na) concentration, but negatively correlated with initial pH and clay content, and not correlated with soil organic carbon (SOC) content. Within the non-carbonate sub-transect, soil pHBC was positively related to initial pH, clay content, CEC and exchangeable Na concentration, but not related to SOC content. Carbonate content was the primary determinant of pHBC in the carbonate containing soils and CEC was the main determinant of buffering capacity in the non-carbonate containing soils. Soil pHBC was positively related to aridity index and carbonate content across the carbonate containing soil sub-transect. Our results indicated that mechanisms controlling pHBC differ among neutral-alkaline soils of northern China, especially between carbonate and non-carbonate containing soils, leading to different rates, risks, and impacts of acidification. This understanding should be incorporated into the acidification risk assessment and landscape management in a changing world.

  12. Contrasting pH buffering patterns in neutral-alkaline soils along a 3600 km transect in northern China

    NASA Astrophysics Data System (ADS)

    Luo, W. T.; Nelson, P. N.; Li, M.-H.; Cai, J. P.; Zhang, Y. Y.; Zhang, Y. G.; Yang, S.; Wang, R. Z.; Wang, Z. W.; Wu, Y. N.; Han, X. G.; Jiang, Y.

    2015-12-01

    Soil pH buffering capacity (pHBC) plays a crucial role in predicting acidification rates, yet its large-scale patterns and controls are poorly understood, especially for neutral-alkaline soils. Here, we evaluated the spatial patterns and drivers of pHBC along a 3600 km long transect (1900 km sub-transect with carbonate-containing soils and 1700 km sub-transect with non-carbonate-containing soils) across northern China. Soil pHBC was greater in the carbonate-containing soils than in the non-carbonate-containing soils. Acid addition decreased soil pH in the non-carbonate-containing soils more markedly than in the carbonate-containing soils. Within the carbonate soil sub-transect, soil pHBC was positively correlated with cation exchange capacity (CEC), carbonate content and exchangeable sodium (Na) concentration, but negatively correlated with initial pH and clay content, and not correlated with soil organic carbon (SOC) content. Within the non-carbonate sub-transect, soil pHBC was positively related to initial pH, clay content, CEC and exchangeable Na concentration, but not related to SOC content. Carbonate content was the primary determinant of pHBC in the carbonate-containing soils and CEC was the main determinant of buffering capacity in the non-carbonate-containing soils. Along the transect, soil pHBC was different in regions with different aridity index. Soil pHBC was positively related to aridity index and carbonate content across the carbonate-containing soil sub-transect. Our results indicated that mechanisms controlling pHBC differ among neutral-alkaline soils of northern China, especially between carbonate- and non-carbonate-containing soils. This understanding should be incorporated into the acidification risk assessment and landscape management in a changing world.

  13. Isolation of a Sulfur-oxidizing Bacterium That can Grow under Alkaline pH, from Corroded Concrete.

    PubMed

    Maeda, T; Negishi, A; Oshima, Y; Nogami, Y; Kamimura, K; Sugio, T

    1998-01-01

    To study the early stages of concrete corrosion by bacteria, sulfur-oxidizing bacterium strain RO-1, which grows in an alkaline thiosulfate medium (pH 10.0) was isolated from corroded concreate and characterized. Strain RO-1 was a Gram negative, rod-shaped bacterium (0.5-0.6×0.9-1.5 μm). The mean G+C content of the DNA of strain RO-1 was 65.0 mol%. Optimum pH and temperature for growth were 8.0. and 30-37°C, respectively. When grown in thiosulfate medium with pH 10.0, growth rate of the strain was 48% of that observed at the optimum pH for growth. Strain RO-1 used sulfide, thiosulfate, and glucose, but not elemental sulfur or tetrathionate, as a sole energy source. Strain RO-1 grew under anaerobic conditions in pepton-NO3 (-) medium containing sodium nitrate as an electron acceptor, and had enzyme activities that oxidized sulfide, elemental sulfur, thiosulfate, sulfite, and glucose, but not tetrathionate. The bacterium had an activity to assimilate (14)CO2 into the cells when thiosulfate was used as an energy source. These results suggest that strain RO-1 is Thiobacillus versutus. Strain RO-1 exuded Ca(2+) from concrete blocks added to thiosulfate medium with pH 9.0 and the pH of the medium decreased from 9.0 to 5.5 after 22 days of cultivation. In contrast, Thiobacillus thiooxidans strain NB1-3 could not exude Ca(2+) in the same thiosulfate medium, suggesting that strain RO-1, but not T. thiooxidans NB1-3, is involved in the early stage of concrete corrosion because concrete structures just after construction contain calcium hydroxide and have a pH of 12-13.

  14. Two pore channel 2 (TPC2) inhibits autophagosomal-lysosomal fusion by alkalinizing lysosomal pH.

    PubMed

    Lu, Yingying; Hao, Bai-Xia; Graeff, Richard; Wong, Connie W M; Wu, Wu-Tian; Yue, Jianbo

    2013-08-16

    Autophagy is an evolutionarily conserved lysosomal degradation pathway, yet the underlying mechanisms remain poorly understood. Nicotinic acid adenine dinucleotide phosphate (NAADP), one of the most potent Ca(2+) mobilizing messengers, elicits Ca(2+) release from lysosomes via the two pore channel 2 (TPC2) in many cell types. Here we found that overexpression of TPC2 in HeLa or mouse embryonic stem cells inhibited autophagosomal-lysosomal fusion, thereby resulting in the accumulation of autophagosomes. Treatment of TPC2 expressing cells with a cell permeant-NAADP agonist, NAADP-AM, further induced autophagosome accumulation. On the other hand, TPC2 knockdown or treatment of cells with Ned-19, a NAADP antagonist, markedly decreased the accumulation of autophagosomes. TPC2-induced accumulation of autophagosomes was also markedly blocked by ATG5 knockdown. Interestingly, inhibiting mTOR activity failed to increase TPC2-induced autophagosome accumulation. Instead, we found that overexpression of TPC2 alkalinized lysosomal pH, and lysosomal re-acidification abolished TPC2-induced autophagosome accumulation. In addition, TPC2 overexpression had no effect on general endosomal-lysosomal degradation but prevented the recruitment of Rab-7 to autophagosomes. Taken together, our data demonstrate that TPC2/NAADP/Ca(2+) signaling alkalinizes lysosomal pH to specifically inhibit the later stage of basal autophagy progression.

  15. The Aspergillus PacC zinc finger transcription factor mediates regulation of both acid- and alkaline-expressed genes by ambient pH.

    PubMed Central

    Tilburn, J; Sarkar, S; Widdick, D A; Espeso, E A; Orejas, M; Mungroo, J; Peñalva, M A; Arst, H N

    1995-01-01

    The pH regulation of gene expression in Aspergillus nidulans is mediated by pacC, whose 678 residue-derived protein contains three putative Cys2His2 zinc fingers. Ten pacCc mutations mimicking growth at alkaline pH remove between 100 and 214 C-terminal residues, including a highly acidic region containing an acidic glutamine repeat. Nine pacC+/- mutations mimicking acidic growth conditions remove between 299 and 505 C-terminal residues. Deletion of the entire pacC coding region mimics acidity but leads additionally to poor growth and conidiation. A PacC fusion protein binds DNA with the core consensus GCCARG. At alkaline ambient pH, PacC activates transcription of alkaline-expressed genes (including pacC itself) and represses transcription of acid-expressed genes. pacCc mutations obviate the need for pH signal transduction. Images PMID:7882981

  16. Comparison of Salivary pH, Buffering Capacity and Alkaline Phosphatase in Smokers and Healthy Non-Smokers

    PubMed Central

    Ahmadi-Motamayel, Fatemeh; Falsafi, Parisa; Goodarzi, Mohammad T.; Poorolajal, Jalal

    2016-01-01

    Objectives: Saliva contains alkaline phosphatase (ALP)—a key intracellular enzyme related to destructive processes and cellular damage—and has buffering capacity (BC) against acids due to the presence of bicarbonate and phosphate ions. Smoking may have deleterious effects on the oral environment due to pH changes which can affect ALP activity. This study aimed to evaluate the salivary pH, BC and ALP activity of male smokers and healthy non-smokers. Methods: This retrospective cohort study took place between August 2012 and December 2013. A total of 251 healthy male non-smokers and 259 male smokers from Hamadan, Iran, were selected. Unstimulated whole saliva was collected from each participant and pH and BC were determined using a pH meter. Salivary enzymes were measured by spectrophotometric assay. Results: Mean salivary pH (7.42 ± 0.48 and 7.52 ± 0.43, respectively; P = 0.018) and BC (3.41 ± 0.54 and 4.17 ± 0.71; P = 0.001) was significantly lower in smokers compared to non-smokers. Mean ALP levels were 49.58 ± 23.33 IU/L among smokers and 55.11 ± 27.85 IU/L among non-smokers (P = 0.015). Conclusion: Significantly lower pH, BC and ALP levels were observed among smokers in comparison to a healthy control group. These salivary alterations could potentially be utilised as biochemical markers for the evaluation of oral tissue function and side-effects among smokers. Further longitudinal studies are recommended to evaluate the effects of smoking on salivary components. PMID:27606111

  17. Optical and electronic properties of conductive ternary nitrides with rare- or alkaline-earth elements

    NASA Astrophysics Data System (ADS)

    Kassavetis, S.; Hodroj, A.; Metaxa, C.; Logothetidis, S.; Pierson, J. F.; Patsalas, P.

    2016-12-01

    Conductive nitrides, such as TiN, are key engineering materials for electronics, photonics, and plasmonics; one of the essential issues for such applications is the ability of tuning the conduction electron density, the resistivity, and the electron scattering. While enhancing the conduction electron density and blueshifting the intraband absorption towards the UV were easily achieved previously, reducing the conduction electron density and redshifting the intraband absorption into the infrared are still an open issue. The latter is achieved in this work by alloying TiN by rare earth (RE = Sc, Y, La) or alkaline earth (AE = Mg, Ca) atoms in Ti substitutional positions. The produced TixRE1-xN and TixAE1-xN thin film samples were grown by a hybrid arc evaporation/sputtering process, and most of them are stable in the B1 cubic structure. Their optical properties were studied in an extensive spectral range by spectroscopic ellipsometry. The ellipsometric spectra were analyzed and quantified by the Drude-Lorentz model, which provided the conduction electron density, the electron mean free path, and the resistivity. The observed interband transitions are firmly assigned, and the optical and electrical properties of TixRE1-xN and TixAE1-xN are quantitatively correlated with their composition and crystal structure.

  18. Proteolytic Activity at Alkaline pH in Oat Leaves, Isolation of an Aminopeptidase 1

    PubMed Central

    Casano, Leonardo M.; Desimone, Marcelo; Trippi, Victorio S.

    1989-01-01

    Proteolytic activity in oat leaf extracts was measured with both azocasein and ribulose bisphosphate carboxylase (Rubisco) as substrates over a wide range of pH (3.0-9.2). With either azocasein or Rubisco activity peaks appeared at pH 4.8, 6.6, and 8.4. An aminopeptidase (AP) which hydrolyzes leucine-nitroanilide was partially purified. Purification consisted of a series of six steps which included ammonium sulfate precipitation, gel filtration, and two ionic exchange chromatographies. The enzyme was purified more than 100-fold. The apparent Km for leucine-nitroanilide is 0.08 millimolar at its pH optimum of 8.4. AP may be a cystein protease since it is inhibited by heavy metals and activated by 2-mercaptoethanol. Isolated chloroplasts were also able to hydrolyze leucine-nitroanilide at a pH optimum of 8.4, indicating that AP could be localized inside the photosynthetic organelles. PMID:16667194

  19. Characterization of steady-state activities of cytochrome c oxidase at alkaline pH: mimicking the effect of K-channel mutations in the bovine enzyme.

    PubMed

    Riegler, David; Shroyer, Lois; Pokalsky, Christine; Zaslavsky, Dmitry; Gennis, Robert; Prochaska, Lawrence J

    2005-01-07

    The cytochrome c oxidase activity of the bovine heart enzyme decreases substantially at alkaline pH, from 650 s(-1) at pH 7.0 to less than 10 s(-1) at pH 9.75. In contrast, the cytochrome c peroxidase activity of the enzyme shows little or no pH dependence (30-50 s(-1)) at pH values greater than 8.5. Under the conditions employed, it is demonstrated that the dramatic decrease in oxidase activity at pH 9.75 is fully reversible and not due to a major alkaline-induced conformational change in the enzyme. Furthermore, the Km values for cytochrome c interaction with the enzyme were also not significantly different at pH 7.8 and pH 9.75, suggesting that the pH dependence of the activity is not due to an altered interaction with cytochrome c at alkaline pH. However, at alkaline pH, the steady-state reduction level of the hemes increased, consistent with a slower rate of electron transfer from heme a to heme a3 at alkaline pH. Since it is well established that the rate of electron transfer from heme a to heme a3 is proton-coupled, it is reasonable to postulate that at alkaline pH, proton uptake becomes rate-limiting. The fact that this is not observed when hydrogen peroxide is used as a substrate in place of O2 suggests that the rate-limiting step is proton uptake via the K-channel associated with the reduction of the heme a3/CuB center prior to the reaction with O2. This step is not required for the reaction with H2O2, as shown previously in the examination of mutants of bacterial oxidases in which the K-channel was blocked. It is concluded that at pH values near 10, the delivery of protons via the K-channel becomes the rate-limiting step in the catalytic cycle with O2, so that the behavior of the bovine enzyme resembles that of the K-channel mutants in the bacterial enzymes.

  20. Effect of Alkaline pH on Polishing and Etching of Single and Polycrystalline Silicon

    NASA Astrophysics Data System (ADS)

    Venkatesh, R. Prasanna; Prasad, Y. Nagendra; Kwon, Tae-Young; Kang, Young-Jae; Park, Jin-Goo

    2012-07-01

    In this paper, the polishing and etching behavior of single and polycrystalline silicon were studied. Prior to chemical mechanical polishing (CMP) process, the surfaces were treated with dilute hydrofluoric acid (DHF) to remove native oxides. The surface analysis shows that the poly contains trace amount of oxygen even after DHF treatment. The static and dynamic etch rates, and removal rates were measured as a function of slurry pH. The single silicon showed a higher static etch rate than the poly. After static etch rate measurements, poly showed higher surface roughness and more hydrophilic which indicates that the surface of poly is different from single crystal silicon. The friction force between pad and substrate and pad temperature was also measured as a function of pH during polishing in order to get more understanding of polishing process. At all the pH values being investigated, poly showed lower dynamic and removal rates, higher friction force and higher temperature. This indicates that the removal of poly in CMP is predominantly by mechanical actions. Also, these results, suggest a mechanism in which the oxygen present in the poly grain boundaries strongly influences the etching and removal mechanism.

  1. Diversity and food web structure of nematode communities under high soil salinity and alkaline pH.

    PubMed

    Salamún, Peter; Kucanová, Eva; Brázová, Tímea; Miklisová, Dana; Renčo, Marek; Hanzelová, Vladimíra

    2014-10-01

    A long-term and intensive magnesium (Mg) ore processing in Slovenské Magnezitové Závody a.s. in Jelšava has resulted in a high Mg content and alkaline pH of the soil environment, noticeable mainly in the close vicinity of the smelter. Nematode communities strongly reacted to the contamination mostly by a decrease in abundance of the sensitive groups. Nematodes from c-p 1 group and bacterivores, tolerant to pollution played a significant role in establishing the dominance at all sites. With increasing distance from the pollution source, the nematode communities were more structured and complex, with an increase in proportion of sensitive c-p 4 and 5 nematodes, composed mainly of carnivores and omnivores. Various ecological indices (e.g. MI2-5, SI, H') indicated similar improvement of farther soil ecosystems.

  2. Catalytically active alkaline molten globular enzyme: Effect of pH and temperature on the structural integrity of 5-aminolevulinate synthase.

    PubMed

    Stojanovski, Bosko M; Breydo, Leonid; Hunter, Gregory A; Uversky, Vladimir N; Ferreira, Gloria C

    2014-12-01

    5-Aminolevulinate synthase (ALAS), a pyridoxal-5'phosphate (PLP)-dependent enzyme, catalyzes the first step of heme biosynthesis in mammals. Circular dichroism (CD) and fluorescence spectroscopies were used to examine the effects of pH (1.0-3.0 and 7.5-10.5) and temperature (20 and 37°C) on the structural integrity of ALAS. The secondary structure, as deduced from far-UV CD, is mostly resilient to pH and temperature changes. Partial unfolding was observed at pH2.0, but further decreasing pH resulted in acid-induced refolding of the secondary structure to nearly native levels. The tertiary structure rigidity, monitored by near-UV CD, is lost under acidic and specific alkaline conditions (pH10.5 and pH9.5/37°C), where ALAS populates a molten globule state. As the enzyme becomes less structured with increased alkalinity, the chiral environment of the internal aldimine is also modified, with a shift from a 420nm to 330nm dichroic band. Under acidic conditions, the PLP cofactor dissociates from ALAS. Reaction with 8-anilino-1-naphthalenesulfonic acid corroborates increased exposure of hydrophobic clusters in the alkaline and acidic molten globules, although the reaction is more pronounced with the latter. Furthermore, quenching the intrinsic fluorescence of ALAS with acrylamide at pH1.0 and 9.5 yielded subtly different dynamic quenching constants. The alkaline molten globule state of ALAS is catalytically active (pH9.5/37°C), although the kcat value is significantly decreased. Finally, the binding of 5-aminolevulinate restricts conformational fluctuations in the alkaline molten globule. Overall, our findings prove how the structural plasticity of ALAS contributes to reaching a functional enzyme.

  3. Application of a fluidized bed reactor charged with aragonite for control of alkalinity, pH and carbon dioxide in marine recirculating aquaculture systems

    USGS Publications Warehouse

    Paul S Wills, PhD; Pfeiffer, Timothy; Baptiste, Richard; Watten, Barnaby J.

    2016-01-01

    Control of alkalinity, dissolved carbon dioxide (dCO2), and pH are critical in marine recirculating aquaculture systems (RAS) in order to maintain health and maximize growth. A small-scale prototype aragonite sand filled fluidized bed reactor was tested under varying conditions of alkalinity and dCO2 to develop and model the response of dCO2 across the reactor. A large-scale reactor was then incorporated into an operating marine recirculating aquaculture system to observe the reactor as the system moved toward equilibrium. The relationship between alkalinity dCO2, and pH across the reactor are described by multiple regression equations. The change in dCO2 across the small-scale reactor indicated a strong likelihood that an equilibrium alkalinity would be maintained by using a fluidized bed aragonite reactor. The large-scale reactor verified this observation and established equilibrium at an alkalinity of approximately 135 mg/L as CaCO3, dCO2 of 9 mg/L, and a pH of 7.0 within 4 days that was stable during a 14 day test period. The fluidized bed aragonite reactor has the potential to simplify alkalinity and pH control, and aid in dCO2 control in RAS design and operation. Aragonite sand, purchased in bulk, is less expensive than sodium bicarbonate and could reduce overall operating production costs.

  4. High-resolution Imaging of pH in Alkaline Sediments and Water Based on a New Rapid Response Fluorescent Planar Optode

    NASA Astrophysics Data System (ADS)

    Han, Chao; Yao, Lei; Xu, Di; Xie, Xianchuan; Zhang, Chaosheng

    2016-05-01

    A new dual-lumophore optical sensor combined with a robust RGB referencing method was developed for two-dimensional (2D) pH imaging in alkaline sediments and water. The pH sensor film consisted of a proton-permeable polymer (PVC) in which two dyes with different pH sensitivities and emission colors: (1) chloro phenyl imino propenyl aniline (CPIPA) and (2) the coumarin dye Macrolex® fluorescence yellow 10 GN (MFY-10 GN) were entrapped. Calibration experiments revealed the typical sigmoid function and temperature dependencies. This sensor featured high sensitivity and fast response over the alkaline working ranges from pH 7.5 to pH 10.5. Cross-sensitivity towards ionic strength (IS) was found to be negligible for freshwater when IS <0.1 M. The sensor had a spatial resolution of approximately 22 μm and aresponse time of <120 s when going from pH 7.0 to 9.0. The feasibility of the sensor was demonstrated using the pH microelectrode. An example of pH image obtained in the natrual freshwater sediment and water associated with the photosynthesis of Vallisneria spiral species was also presented, suggesting that the sensor held great promise for the field applications.

  5. High-resolution Imaging of pH in Alkaline Sediments and Water Based on a New Rapid Response Fluorescent Planar Optode

    PubMed Central

    Han, Chao; Yao, Lei; Xu, Di; Xie, Xianchuan; Zhang, Chaosheng

    2016-01-01

    A new dual-lumophore optical sensor combined with a robust RGB referencing method was developed for two-dimensional (2D) pH imaging in alkaline sediments and water. The pH sensor film consisted of a proton-permeable polymer (PVC) in which two dyes with different pH sensitivities and emission colors: (1) chloro phenyl imino propenyl aniline (CPIPA) and (2) the coumarin dye Macrolex® fluorescence yellow 10 GN (MFY-10 GN) were entrapped. Calibration experiments revealed the typical sigmoid function and temperature dependencies. This sensor featured high sensitivity and fast response over the alkaline working ranges from pH 7.5 to pH 10.5. Cross-sensitivity towards ionic strength (IS) was found to be negligible for freshwater when IS <0.1 M. The sensor had a spatial resolution of approximately 22 μm and aresponse time of <120 s when going from pH 7.0 to 9.0. The feasibility of the sensor was demonstrated using the pH microelectrode. An example of pH image obtained in the natrual freshwater sediment and water associated with the photosynthesis of Vallisneria spiral species was also presented, suggesting that the sensor held great promise for the field applications. PMID:27199163

  6. Roles of alkaline phosphatase and labile internal mineral in matrix vesicle-mediated calcification. Effect of selective release of membrane-bound alkaline phosphatase and treatment with isosmotic pH 6 buffer.

    PubMed

    Register, T C; McLean, F M; Low, M G; Wuthier, R E

    1986-07-15

    The roles of alkaline phosphatase and labile internal mineral in matrix vesicle-mediated mineralization have been studied by selectively releasing the enzyme from a wide variety of matrix vesicle preparations using treatment with a bacterial phosphatidylinositol-specific phospholipase C and by demineralization of the vesicles using isosmotic pH 6 buffer. Following depletion of 50-90% of the alkaline phosphatase activity or treatment with citrate buffer, the vesicles were tested for their ability to accumulate 45Ca2+ and 32Pi from a synthetic cartilage lymph. Removal of alkaline phosphatase by phospholipase C treatment caused two principal effects, depending on the matrix vesicle preparation. In rapidly mineralizing vesicle fractions which did not require organic phosphate esters (Po) to accumulate mineral ions, release of alkaline phosphatase had only a minor effect. In slowly mineralizing vesicles preparations or those dependent on Po substrates for mineral ion uptake, release of alkaline phosphatase caused significant loss of mineralizing activity. The activity of rapidly calcifying vesicles was shown to be dependent on the presence of labile internal mineral, as demonstrated by major loss in activity when the vesicles were decalcified by various treatments. Ion uptake by demineralized vesicles or those fractionated on sucrose step gradients required Po and was significantly decreased by alkaline phosphatase depletion. Uptake of Pi, however, was not coupled with hydrolysis of the Po substrate. These findings argue against a direct role for alkaline phosphatase as a porter in matrix vesicle Pi uptake, contrary to previous postulates. The results emphasize the importance of internal labile mineral in rapid uptake of mineral ions by matrix vesicles.

  7. High external pH enables more efficient secretion of alkaline α-amylase AmyK38 by Bacillus subtilis

    PubMed Central

    2012-01-01

    Background Bacillus subtilis genome-reduced strain MGB874 exhibits enhanced production of exogenous extracellular alkaline cellulase Egl-237 and subtilisin-like alkaline protease M-protease. Here, we investigated the suitability of strain MGB874 for the production of α-amylase, which was anticipated to provoke secretion stress responses involving the CssRS (Control secretion stress Regulator and Sensor) system. Results Compared to wild-type strain 168, the production of a novel alkaline α-amylase, AmyK38, was severely decreased in strain MGB874 and higher secretion stress responses were also induced. Genetic analyses revealed that these phenomena were attributable to the decreased pH of growth medium as a result of the lowered expression of rocG, encoding glutamate dehydrogenase, whose activity leads to NH3 production. Notably, in both the genome-reduced and wild-type strains, an up-shift of the external pH by the addition of an alkaline solution improved AmyK38 production, which was associated with alleviation of the secretion stress response. These results suggest that the optimal external pH for the secretion of AmyK38 is higher than the typical external pH of growth medium used to culture B. subtilis. Under controlled pH conditions, the highest production level (1.08 g l-1) of AmyK38 was obtained using strain MGB874. Conclusions We demonstrated for the first time that RocG is an important factor for secretory enzyme production in B. subtilis through its role in preventing acidification of the growth medium. As expected, a higher external pH enabled a more efficient secretion of the alkaline α-amylase AmyK38 in B. subtilis. Under controlled pH conditions, the reduced-genome strain MGB874 was demonstrated to be a beneficial host for the production of AmyK38. PMID:22681752

  8. Microprofiles of oxygen, redox potential, and pH, and microbial fermentation products in the highly alkaline gut of the saprophagous larva of Penthetria holosericea (Diptera: Bibionidae).

    PubMed

    Šustr, Vladimír; Stingl, Ulrich; Brune, Andreas

    2014-08-01

    The saprophagous larvae of bibionid flies harbor bacteria in their alkaline intestinal tracts, but little is known about the contribution of the gut microbiota to the digestion of their recalcitrant diet. In this study, we measured oxygen and hydrogen partial pressure, redox potential and pH in the midgut, gastric caeca and hindgut of larvae of the bibionid fly Penthetria holosericea with Clark-type O2 and H2 microsensors, platinum redox microelectrodes, and LIX-type pH microelectrodes. The center of the midgut lumen was anoxic, whereas gastric caeca and hindgut were hypoxic. However, redox potential profiles indicated oxidizing conditions throughout the gut, with lowest values in the midgut (+20 to +60mV). Hydrogen production was not detected. The midgut was extremely alkaline (pH around 11), whereas hindgut and gastric caeca were neutral to slightly alkaline. While HPLC analysis showed high concentrations of glucose in the midgut (15mM) and gastric caeca (27mM), the concentrations of microbial fermentation products such as lactate (2-4mM), acetate (<1mM) and succinate (<0.5mM) were low in all gut regions, suggesting that the contribution of microorganisms to the digestive process, particularly in the alkaline midgut, is only of minor importance. We conclude that the digestive strategy of the saprophytic larva of P. holosericea, which feeds selectively on decomposed leaves and its own microbe-rich faeces, differs fundamentally from those of detritivorous and humivorous insects, which host a highly active, fermentative microbiota in their alkaline midgut or hindgut compartments.

  9. pH- and voltage-dependent conductances in toad skin.

    PubMed

    Lacaz-Vieira, F

    1995-11-01

    The present study focuses on two closely related topics on ion conductance in toad skins: (i) the interaction of apical protons with the apical voltage-dependent Cl(-)-activated channels of the mitochondria-rich cells, and (ii) the description and characterization of a novel subject, a voltage-dependent H(+)-activated conductance. The Cl- conductance (GCl) is activated by tissue hyperpolarization (which leads to apical membrane depolarization) and the presence of Cl- ions in the apical solution. Increasing apical proton concentration (from pH 8 to pH 4) impairs the process of activation of the Cl- conductive pathway, slowing the kinetics of It activation and reducing the steady-stage values of Gt and It. This effect is markedly voltage-dependent since no effect is seen at Vt = -100 mv and is fully present at -50 mV. The voltage-dependence of the pH effect suggests that the critical protonation sites of the apical Cl- channels are not freely exposed to the apical solution but dwell within the membrane electric field. An also coherent interpretation is that titration of apical proton binding sites affects the gating of the voltage-dependent Cl- channels, shifting the conductance-vs.-voltage curve to more negative clamping potentials. Tissue conductance in the absence of apical Cl- ions can be importantly affected by the pH of the apical solution (pHa), the effect being markedly dependent on the clamping potential. Generally speaking, the effect of rising apical proton concentration can be conspicuous at negative clamping potentials, while at positive potentials changes in tissue conductance were never observed. For a clamping potential of -100 mV, a turning point somewhere between pHa = 4 and pHa = 3 was observed. Apical acidification to pH 4 has no effect upon tissue conductance while apical acidification to pH 3 leads to a marked, slow and reversible increase of tissue conductance. A striking similitude exists between the voltage-dependent Cl(-)-gated conductance

  10. Strategies for regulation of hemolymph pH in acidic and alkaline water by the larval mosquito Aedes aegypti (L.) (Diptera; Culicidae).

    PubMed

    Clark, Thomas M; Vieira, Marcus A L; Huegel, Kara L; Flury, Dawn; Carper, Melissa

    2007-12-01

    The responses of larval Aedes aegypti to media of pH 4, 7 and 11 provide evidence for pH regulatory strategies. Drinking rates in pH 4 media were elevated 3- to 5-fold above those observed in pH 7 or 11. Total body water was elevated during acute exposure to acidic media. During chronic exposure, total body water was decreased and Malpighian tubule mitochondrial luminosity, quantified using Mitotracker Green FM, increased. Malpighian tubule secretion rates and energy demands thus appear to increase dramatically during acid exposure. In alkaline media, drinking rates were quite low. Larvae in pH 11 media excreted net acid (0.12 nequiv H(+) g(-1) h(-1)) and the pH indicators azolitmin and bromothymol blue revealed that the rectal lumen is acidic in vivo at all ambient pH values. The anal papillae (AP) were found to be highly permeant to acid-base equivalents. Ambient pH influenced the length, and the mass-specific length, of the AP in the presence of NaCl (59.9 mmol l(-1)). In contrast, the length and mass-specific length of AP were not influenced by ambient pH in low NaCl conditions. Mitochondrial luminosity was reduced in AP of larvae reared in acidic media, and was not elevated in alkaline media, relative to that of larvae reared in neutral media. These data suggest that the AP may compromise acid-base balance in acidic media, and may also be an important site of trade-offs between H(+) homeostasis and NaCl uptake in dilute, acidic media.

  11. High pH (and not free ammonia) is responsible for Anammox inhibition in mildly alkaline solutions with excess of ammonium.

    PubMed

    Puyol, D; Carvajal-Arroyo, J M; Li, G B; Dougless, A; Fuentes-Velasco, M; Sierra-Alvarez, R; Field, J A

    2014-10-01

    Ammonium is a substrate of the anaerobic ammonium oxidation (Anammox) process but it has been suggested as a substrate-inhibitor because of the action of its unionized form, free ammonia. High pH of the medium is also an important limiting factor of the Anammox bacteria. Both effects are difficult to discriminate. In this work the inhibitory effects of high pH, total ammonia (TA) and NH3 on the Anammox process were investigated simultaneously. Results confirmed that TA caused no inhibition and high pH is a much more important inhibiting factor than NH3 in mildly alkaline conditions, based on a multi-factorial analysis. Values of pH higher than 7.6 caused Anammox inhibition >10 % and should be avoided during the application of the Anammox process in practice.

  12. Alkaline pH Is a signal for optimal production and secretion of the heat labile toxin, LT in enterotoxigenic Escherichia coli (ETEC).

    PubMed

    Gonzales, Lucia; Ali, Zahra Bagher; Nygren, Erik; Wang, Zhiyun; Karlsson, Stefan; Zhu, Baoli; Quiding-Järbrink, Marianne; Sjöling, Åsa

    2013-01-01

    Enterotoxigenic Escherichia coli (ETEC) cause secretory diarrhea in children and travelers to endemic areas. ETEC spreads through the fecal-oral route. After ingestion, ETEC passes through the stomach and duodenum before it colonizes the lower part of the small intestine, exposing bacteria to a wide range of pH and environmental conditions. This study aimed to determine the impact of external pH and activity of the Cyclic AMP receptor protein (CRP) on the regulation of production and secretion of heat labile (LT) enterotoxin. ETEC strain E2863wt and its isogenic mutant E2863ΔCRP were grown in LBK media buffered to pH 5, 7 and 9. GM1 ELISA, cDNA and cAMP analyses were carried out on bacterial pellet and supernatant samples derived from 3 and 5 hours growth and from overnight cultures. We confirm that CRP is a repressor of LT transcription and production as has been shown before but we show for the first time that CRP is a positive regulator of LT secretion both in vitro and in vivo. LT secretion increased at neutral to alkaline pH compared to acidic pH 5 where secretion was completely inhibited. At pH 9 secretion of LT was optimal resulting in 600 percent increase of secreted LT compared to unbuffered LBK media. This effect was not due to membrane leakage since the bacteria were viable at pH 9. The results indicate that the transition to the alkaline duodenum and/or exposure to high pH close to the epithelium as well as activation of the global transcription factor CRP are signals that induce secretion of the LT toxin in ETEC.

  13. Combined effects of carbonate alkalinity and pH on survival, growth and haemocyte parameters of the Venus clam Cyclina sinensis.

    PubMed

    Lin, Tingting; Lai, Qifang; Yao, Zongli; Lu, Jianxue; Zhou, Kai; Wang, Hui

    2013-08-01

    Carbonate alkalinity (CA) and pH are considered to be two important stress factors that determine the response of aquatic animals to sudden transfers into saline-alkaline water. To evaluate the potential for aquaculture production of Venus clams (Cyclina sinensis) farmed in saline-alkaline water, the combined effects of CA (2.5 (control), 10.0, 20.0 and 40.0 meq/l) and pH (8.0 (control), 8.5, 9.0 and 9.5) on survival rate was monitored every day for 10 days. Length gain rate (LGR) and weight gain rate (WGR) were also monitored for two months, and total haemocyte count (THC), phagocytic rate (PR) and haemocyte mortality (HM) were measured for 3, 6, 12 and 24 days under the same water temperature (20 °C) and salinity (15‰) conditions. The results showed that survival rates in treatments of CA ≤ 20.0, combined with pH ≤ 9.0, were 100%. LGR and WGR in treatments of CA 2.5 & pH 8.0 (control), CA 2.5 & pH 8.5 and CA 10.0 & pH 8.0 exhibited the largest values (P > 0.05), while in other treatments, they showed a decreasing trend with an increase in either CA or pH or both (P < 0.05). Similarly, for THC, PR and HM, no significant differences were observed among the fast growth treatments during the entire experimental period (P > 0.05), however, in other treatments, they presented significant differences, especially on day 3 and 6 (P < 0.05), most notably with increases in CA or pH, but returned to control levels on day 12. In conclusion, in this study, a strong interaction between CA and pH was observed. Additionally, it was ascertained that the Venus clam C. sinensis can withstand the stress of CA 20.0 combined pH 9.0, although individuals grows slowly and may take approximately 12 days to recover to the unstressed condition.

  14. DEVELOPMENT AND SELECTION OF IONIC LIQUID ELECTROLYTES FOR HYDROXIDE CONDUCTING POLYBENZIMIDAZOLE MEMBRANES IN ALKALINE FUEL CELLS

    SciTech Connect

    Fox, E.

    2012-05-01

    Alkaline fuel cell (AFC) operation is currently limited to specialty applications such as low temperatures and pure HO due to the corrosive nature of the electrolyte and formation of carbonates. AFCs are the cheapest and potentially most efficient (approaching 70%) fuel cells. The fact that non-Pt catalysts can be used, makes them an ideal low cost alternative for power production. The anode and cathode are separated by and solid electrolyte or alkaline porous media saturated with KOH. However, CO from the atmosphere or fuel feed severely poisons the electrolyte by forming insoluble carbonates. The corrosivity of KOH (electrolyte) limits operating temperatures to no more than 80°C. This chapter examines the development of ionic liquids electrolytes that are less corrosive, have higher operating temperatures, do not chemically bond to CO and enable alternative fuels. Work is detailed on the IL selection and characterization as well as casting methods within the polybenzimidazole based solid membrane. This approach is novel as it targets the root of the problem (the electrolyte) unlike other current work in alkaline fuel cells which focus on making the fuel cell components more durable.

  15. Effect of Treatment pH on the End Products of the Alkaline Hydrolysis of TNT and RDX

    DTIC Science & Technology

    2007-06-01

    Comparison of final TOC of TNT alkaline hydrolysis solutions at three pHs........................19 Table 7. Results of ion chromatographic analysis ...25 Table 12. Results of ion chromatographic analysis of unlabeled RDX solutions following extended alkaline hydrolysis at three...8330 explo- sives analysis TOC IC Lime Control ERDC/EL TR-07-4 7 3 Materials and Methods Chemicals Chemicals used in this study included

  16. Improving the expression of recombinant proteins in E. coli BL21 (DE3) under acetate stress: an alkaline pH shift approach.

    PubMed

    Wang, Hengwei; Wang, Fengqing; Wang, Wei; Yao, Xueling; Wei, Dongzhi; Cheng, Hairong; Deng, Zixin

    2014-01-01

    Excess acetate has long been an issue for the production of recombinant proteins in E. coli cells. Recently, improvements in acetate tolerance have been achieved through the use of genetic strategies and medium supplementation with certain amino acids and pyrimidines. The aim of our study was to evaluate an alternative to improve the acetate tolerance of E. coli BL21 (DE3), a popular strain used to express recombinant proteins. In this work we reported the cultivation of BL21 (DE3) in complex media containing acetate at high concentrations. In the presence of 300 mM acetate, compared with pH 6.5, pH 7.5 improved cell growth by approximately 71%, reduced intracellular acetate by approximately 50%, and restored the expression of glutathione S-transferase (GST), green fluorescent protein (GFP) and cytochrome P450 monooxygenase (CYP). Further experiments showed that alkaline pHs up to 8.5 had little inhibition in the expression of GST, GFP and CYP. In addition, the detrimental effect of acetate on the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) by the cell membrane, an index of cellular metabolic capacity, was substantially alleviated by a shift to alkaline pH values of 7.5-8.0. Thus, we suggest an approach of cultivating E. coli BL21 (DE3) at pH 8.0 ± 0.5 to minimize the effects caused by acetate stress. The proposed strategy of an alkaline pH shift is a simple approach to solving similar bioprocessing problems in the production of biofuels and biochemicals from sugars.

  17. Hydrolysis and volatile fatty acids accumulation of waste activated sludge enhanced by the combined use of nitrite and alkaline pH.

    PubMed

    Huang, Cheng; Liu, Congcong; Sun, Xiuyun; Sun, Yinglu; Li, Rui; Li, Jiansheng; Shen, Jinyou; Han, Weiqing; Liu, Xiaodong; Wang, Lianjun

    2015-12-01

    Volatile fatty acids (VFAs) production from anaerobic digestion of waste activated sludge (WAS) is often limited by the slow hydrolysis and/or poor substrate availability. Increased attention has been given to enhance the hydrolysis and acidification of WAS recently. This study presented an efficient and green strategy based on the combined use of nitrite pretreatment and alkaline pH to stimulate hydrolysis and VFA accumulation from WAS. Results showed that both proteins and polysaccharides increased in the presence of nitrite, indicating the enhancement of sludge solubilization and hydrolysis processes. Mechanism investigations showed that nitrite pretreatment could disintegrate the sludge particle and disperse extracellular polymeric substances (EPS). Then, anaerobic digestion tests demonstrated VFA production increased with nitrite treatment. The maximal VFA accumulation was achieved with 0.1 g N/L nitrite dosage and pH 10.0 at a sludge retention time (SRT) of 7 days, which was much higher VFA production in comparison with the blank, sole nitrite pretreatment, or sole pH 10. The potential analysis suggested that the combined nitrite pretreatment and alkaline pH is capable of enhancing WAS digestion with a great benefit for biological nutrient removal (BNR).

  18. The Effect of Carbonate and pH on Hydrogen Oxidation and Oxygen Reduction on Pt-Based Electrocatalysts in Alkaline Media

    DOE PAGES

    John, Samuel St.; Atkinson, Robert W.; Roy, Asa; ...

    2016-01-11

    In this paper, we investigated the performance of several carbon-supported RuxPty electrocatalysts for their alkaline hydrogen oxidation and oxygen reduction performance in the presence of carbonate and compared their performance with monometallic, carbon-supported Pt. Our results indicate a strong dependence of HOR upon pH for the monometallic Pt catalysts (22 mV/pH) and a weak dependence upon pH for the Ru-containing electrocatalysts (3.7, 2.5, and 4.7 mV/pH on Ru0.2Pt0.8, Ru0.4Pt0.6, and Ru0.8Pt0.2, respectively). These results are consistent with our previous findings that illustrate a change in rds from electron transfer (on monometallic Pt) to dissociative hydrogen adsorption (on RuxPty catalysts). Analysismore » of the kinetic currents to determine the rate-determining step via Tafel slope analysis provides additional data supporting this conclusion. There is no difference in the performance at comparable pH values in the presence or absence of carbonate on monometallic Pt indicating that water/hydroxide is the primary proton acceptor for alkaline HOR in 0.1 M KOH aqueous electrolyte. Finally, we observe no pH or carbonate dependence for the ORR on monometallic Pt.« less

  19. Ensuring PhD development of responsible conduct of research behaviors: who's responsible?

    PubMed

    Titus, Sandra L; Ballou, Janice M

    2014-03-01

    The importance of public confidence in scientific findings and trust in scientists cannot be overstated. Thus, it becomes critical for the scientific community to focus on enhancing the strategies used to educate future scientists on ethical research behaviors. What we are lacking is knowledge on how faculty members shape and develop ethical research standards with their students. We are presenting the results of a survey with 3,500 research faculty members. We believe this is the first report on how faculty work with and educate their PhD students on basic research standards. Specifically, we wanted to determine whether individual faculty members, who are advisors or mentors, differ in how they implemented components of responsible conduct of research (RCR) with their PhD students. Mentors were more likely than advisors or supervisors to report working with all of their PhDs, who graduated in the last 5 years, on the 17 recognized critical components of RCR training and research skill development. We also found about half of the faculty members believe RCR is an institutional responsibility versus a faculty responsibility. Less than a quarter have had opportunities to participate in faculty training to be a better mentor, advisor, or research teacher, and about one third of faculty did not or could not remember whether they had guidelines related to their responsibilities to PhD students. We discuss the implications of our findings and focus on ways that PhD research mentoring can be enhanced.

  20. Pho4 Is Essential for Dissemination of Cryptococcus neoformans to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH

    PubMed Central

    Kaufman-Francis, Keren; Desmarini, Desmarini; Juillard, Pierre G.; Li, Cecilia; Stifter, Sebastian A.; Feng, Carl G.; Sorrell, Tania C.; Grau, Georges E. R.; Bahn, Yong-Sun

    2017-01-01

    ABSTRACT Phosphate acquisition by fungi is regulated by the phosphate-sensing and acquisition (PHO) signaling pathway. Cryptococcus neoformans disseminates from the lung to the brain and is the commonest cause of fungal meningitis worldwide. To investigate the contribution of PHO signaling to cryptococcal dissemination, we characterized a transcription factor knockout strain (hlh3Δ/pho4Δ) defective in phosphate acquisition. Despite little similarity with other fungal Pho4 proteins, Hlh3/Pho4 functioned like a typical phosphate-responsive transcription factor in phosphate-deprived cryptococci, accumulating in nuclei and triggering expression of genes involved in phosphate acquisition. The pho4Δ mutant strain was susceptible to a number of stresses, the effect of which, except for alkaline pH, was alleviated by phosphate supplementation. Even in the presence of phosphate, the PHO pathway was activated in wild-type cryptococci at or above physiological pH, and under these conditions, the pho4Δ mutant had a growth defect and compromised phosphate uptake. The pho4Δ mutant was hypovirulent in a mouse inhalation model, where dissemination to the brain was reduced dramatically, and markedly hypovirulent in an intravenous dissemination model. The pho4Δ mutant was not detected in blood, nor did it proliferate significantly when cultured with peripheral blood monocytes. In conclusion, dissemination of infection and the pathogenesis of meningitis are dependent on cryptococcal phosphate uptake and stress tolerance at alkaline pH, both of which are Pho4 dependent. IMPORTANCE Cryptococcal meningitis is fatal without treatment and responsible for more than 500,000 deaths annually. To be a successful pathogen, C. neoformans must obtain an adequate supply of essential nutrients, including phosphate, from various host niches. Phosphate acquisition in fungi is regulated by the PHO signaling cascade, which is activated when intracellular phosphate decreases below a critical

  1. Continuous-flow electrophoresis: Membrane-associated deviations of buffer pH and conductivity

    NASA Technical Reports Server (NTRS)

    Smolka, A. J. K.; Mcguire, J. K.

    1978-01-01

    The deviations in buffer pH and conductivity which occur near the electrode membranes in continuous-flow electrophoresis were studied in the Beckman charged particle electrophoresis system and the Hanning FF-5 preparative electrophoresis instrument. The nature of the membranes separating the electrode compartments from the electrophoresis chamber, the electric field strength, and the flow rate of electrophoresis buffer were all found to influence the formation of the pH and conductivity gradients. Variations in electrode buffer flow rate and the time of electrophoresis were less important. The results obtained supported the hypothesis that a combination of Donnan membrane effects and the differing ionic mobilities in the electrophoresis buffer was responsible for the formation of the gradients. The significance of the results for the design and stable operation of continuous-flow electrophoresis apparatus was discussed.

  2. Snow leopard (Panthera uncia) spermatozoa are sensitive to alkaline pH, but motility in vitro is not influenced by protein or energy supplements.

    PubMed

    Roth, T L; Swanson, W F; Collins, D; Burton, M; Garell, D M; Wildt, D E

    1996-01-01

    To better understand the biology of snow leopard spermatozoa and to facilitate developing assisted reproduction, a series of studies was conducted to: 1) identify the component(s) of complex culture media responsible for the detrimental effect on sperm survival in vitro, 2) optimize medium for supporting sperm viability, and 3) evaluate sperm capacitation in vitro. Constituents of complex media were added systematically to phosphate-buffered saline (PBS) to isolate the factor(s) influencing snow leopard sperm motility in vitro. Sperm capacitation was also assessed following incubation in PBS with bovine serum albumin (BSA), fetal calf serum (FCS), or heparin. For maintaining sperm motility, there was no benefit (P > or = 0.05) to supplementing PBS with low (5%) or high (20%) concentrations of snow leopard serum (SLS) versus FCS or BSA. Likewise, adding supplemental energy substrates (pyruvate, glucose, lactate, or glutamine) did not enhance or hinder (P > or = 0.05) sperm motility. However, motility rapidly decreased (P < 0.05) with the addition of NaHCO3 to PBS or Ham's F10 nutrient mixture. Surprisingly, Ham's F10 with no buffering component or with both NaHCO3 and N-Z-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) maintained sperm motility at levels similar (P > or = 0.05) to PBS. Although sperm motility in all treatments decreased with time, there was a strong inverse relationship (P < 0.01; r = 0.90) between motility and sample pH at 6 hours. Spermatozoa incubated in PBS containing FCS, BSA, or heparin did not undergo the acrosome reaction when exposed to calcium ionophore. In summary, alkaline pH has a profound detrimental effect on snow leopard sperm motility, and capacitation does not occur under conditions that normally promote this event in other felid species. These results clearly demonstrate a high degree of interspecific variation among felids in fundamental sperm function, and they provide evidence for the necessity of basic research when

  3. Enhanced production of heterologous proteins by the filamentous fungus Trichoderma reesei via disruption of the alkaline serine protease SPW combined with a pH control strategy.

    PubMed

    Zhang, Guoxiu; Zhu, Yao; Wei, Dongzhi; Wang, Wei

    2014-01-01

    The filamentous fungus Trichoderma reesei has received attention as a host for heterologous protein production because of its high secretion capacity and eukaryotic post-translational modifications. However, the heterologous production of proteins in T. reesei is limited by its high expression of proteases. The pH control strategies have been proposed for eliminating acidic, but not alkaline, protease activity. In this study, we verified the expression of a relatively major extracellular alkaline protease (GenBank accession number: EGR49466.1, named spw in this study) from 20 candidates through real-time polymerase chain reaction. The transcriptional level of spw increased about 136 times in response to bovine serum albumin as the sole nitrogen source. Additionally, extracellular protease activity was reduced by deleting the spw gene. Therefore, using this gene expression system, we observed enhanced production and stability of the heterologous alkaline endoglucanase EGV from Humicola insolens using the Δspw strain as compared to the parental strain RUT-C30.

  4. The Effect of Carbonate and pH on Hydrogen Oxidation and Oxygen Reduction on Pt-Based Electrocatalysts in Alkaline Media

    SciTech Connect

    John, Samuel St.; Atkinson, Robert W.; Roy, Asa; Unocic, Raymond R.; Papandrew, Alexander B.; Zawodzinski, Thomas A.

    2016-01-11

    In this paper, we investigated the performance of several carbon-supported RuxPty electrocatalysts for their alkaline hydrogen oxidation and oxygen reduction performance in the presence of carbonate and compared their performance with monometallic, carbon-supported Pt. Our results indicate a strong dependence of HOR upon pH for the monometallic Pt catalysts (22 mV/pH) and a weak dependence upon pH for the Ru-containing electrocatalysts (3.7, 2.5, and 4.7 mV/pH on Ru0.2Pt0.8, Ru0.4Pt0.6, and Ru0.8Pt0.2, respectively). These results are consistent with our previous findings that illustrate a change in rds from electron transfer (on monometallic Pt) to dissociative hydrogen adsorption (on RuxPty catalysts). Analysis of the kinetic currents to determine the rate-determining step via Tafel slope analysis provides additional data supporting this conclusion. There is no difference in the performance at comparable pH values in the presence or absence of carbonate on monometallic Pt indicating that water/hydroxide is the primary proton acceptor for alkaline HOR in 0.1 M KOH aqueous electrolyte. Finally, we observe no pH or carbonate dependence for the ORR on monometallic Pt.

  5. Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity

    SciTech Connect

    Du, Mao -Hua; Singh, David J.; Zhang, Lijun; Li, Yuwei; Xu, Qiaoling; Ma, Yanming; Zheng, Weitao

    2016-04-19

    Oxides with good p-type conductivity have been long sought after to achieve high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides are promising candidates because of their rather dispersive upper valence bands caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known Sn(II) oxides being p-type conductive suitable for device applications. Here, we present via first-principles global optimization structure searches a material design study for a hitherto unexplored Sn(II)-based system, ternary alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca, Sr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can be stabilized by Sn-rich conditions in phase stability diagrams. Their structures follow the Zintl behaviour and consist of basic structural motifs of SnO3 tetrahedra. Unexpectedly they show distinct electronic properties with band gaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective masses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further exploration of metastable phases indicates a wide tunability of electronic properties controlled by the details of the bonding between the basic structural motifs. Lastly, this suggests further exploration of alkaline-earth metal Sn(II) oxides for potential applications requiring good p-type conductivity such as transparent conductors and photovoltaic absorbers.

  6. Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity

    DOE PAGES

    Du, Mao -Hua; Singh, David J.; Zhang, Lijun; ...

    2016-04-19

    Oxides with good p-type conductivity have been long sought after to achieve high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides are promising candidates because of their rather dispersive upper valence bands caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known Sn(II) oxides being p-type conductive suitable for device applications. Here, we present via first-principles global optimization structure searches a material design study for a hitherto unexplored Sn(II)-based system, ternary alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca, Sr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can bemore » stabilized by Sn-rich conditions in phase stability diagrams. Their structures follow the Zintl behaviour and consist of basic structural motifs of SnO3 tetrahedra. Unexpectedly they show distinct electronic properties with band gaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective masses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further exploration of metastable phases indicates a wide tunability of electronic properties controlled by the details of the bonding between the basic structural motifs. Lastly, this suggests further exploration of alkaline-earth metal Sn(II) oxides for potential applications requiring good p-type conductivity such as transparent conductors and photovoltaic absorbers.« less

  7. Using Simulation in Nursing PhD Education: Facilitating Application of Responsible Conduct of Research Principles.

    PubMed

    Clayton, Margaret F; Supiano, Katherine; Wilson, Rebecca; Lassche, Madeline; Latendresse, Gwen

    Simulation is a standard clinical nursing educational approach; however, simulation is rarely used in nonclinical nursing education. In doctor of philosophy (PhD) programs, ethical content about responsible conduct of research (RCR) is traditionally didactic, presented early in the program of study. Ethics content merits review before students begin the dissertation phase; thus, the purpose of this project was to design and implement simulated scenarios to help students apply RCR principles prior to beginning independent research. Two scenarios were developed: (a) a potential protocol change discussed in a research team meeting and (b) an in-home data collection experience with an elderly participant and her daughter. Actors were trained faculty volunteers, playing roles outside their usual academic positions. Faculty facilitated scenarios by posing questions as cues related to desired learning outcomes as scenarios unfolded. Eleven nursing PhD students and 6 faculty participated. Debriefing facilitated discussion of RCR principles, common research quandaries, and suggested scenario revisions. Faculty, expert observation, and video-review showed that younger and less experienced students tried to give the "right" answer rather than implement RCR appropriate solutions. Students with more clinical experience had difficulty adopting the less familiar researcher role. Overall, simulation is a novel and useful way to enhance RCR content in PhD programs.

  8. Halotolerant cyanobacterium Aphanothece halophytica contains NapA-type Na+/H+ antiporters with novel ion specificity that are involved in salt tolerance at alkaline pH.

    PubMed

    Wutipraditkul, Nuchanat; Waditee, Rungaroon; Incharoensakdi, Aran; Hibino, Takashi; Tanaka, Yoshito; Nakamura, Tatsunosuke; Shikata, Masamitsu; Takabe, Tetsuko; Takabe, Teruhiro

    2005-08-01

    Aphanothece halophytica is a halotolerant alkaliphilic cyanobacterium which can grow at NaCl concentrations up to 3.0 M and at pH values up to 11. The genome sequence revealed that the cyanobacterium Synechocystis sp. strain PCC 6803 contains five putative Na+/H+ antiporters, two of which are homologous to NhaP of Pseudomonas aeruginosa and three of which are homologous to NapA of Enterococcus hirae. The physiological and functional properties of NapA-type antiporters are largely unknown. One of NapA-type antiporters in Synechocystis sp. strain PCC 6803 has been proposed to be essential for the survival of this organism. In this study, we examined the isolation and characterization of the homologous gene in Aphanothece halophytica. Two genes encoding polypeptides of the same size, designated Ap-napA1-1 and Ap-napA1-2, were isolated. Ap-NapA1-1 exhibited a higher level of homology to the Synechocystis ortholog (Syn-NapA1) than Ap-NapA1-2 exhibited. Ap-NapA1-1, Ap-NapA1-2, and Syn-NapA1 complemented the salt-sensitive phenotypes of an Escherichia coli mutant and exhibited strongly pH-dependent Na+/H+ and Li+/H+ exchange activities (the highest activities were at alkaline pH), although the activities of Ap-NapA1-2 were significantly lower than the activities of the other polypeptides. Only one these polypeptides, Ap-NapA1-2, complemented a K+ uptake-deficient E. coli mutant and exhibited K+ uptake activity. Mutagenesis experiments suggested the importance of Glu129, Asp225, and Asp226 in the putative transmembrane segment and Glu142 in the loop region for the activity. Overexpression of Ap-NapA1-1 in the freshwater cyanobacterium Synechococcus sp. strain PCC 7942 enhanced the salt tolerance of cells, especially at alkaline pH. These findings indicate that A. halophytica has two NapA1-type antiporters which exhibit different ion specificities and play an important role in salt tolerance at alkaline pH.

  9. Extracellular pH alkalinization by Cl-/HCO3- exchanger is crucial for TASK2 activation by hypotonic shock in proximal cell lines from mouse kidney.

    PubMed

    L'Hoste, S; Barriere, H; Belfodil, R; Rubera, I; Duranton, C; Tauc, M; Poujeol, C; Barhanin, J; Poujeol, P

    2007-02-01

    We have previously shown that K(+)-selective TASK2 channels and swelling-activated Cl(-) currents are involved in a regulatory volume decrease (RVD; Barriere H, Belfodil R, Rubera I, Tauc M, Lesage F, Poujeol C, Guy N, Barhanin J, Poujeol P. J Gen Physiol 122: 177-190, 2003; Belfodil R, Barriere H, Rubera I, Tauc M, Poujeol C, Bidet M, Poujeol P. Am J Physiol Renal Physiol 284: F812-F828, 2003). The aim of this study was to determine the mechanism responsible for the activation of TASK2 channels during RVD in proximal cell lines from mouse kidney. For this purpose, the patch-clamp whole-cell technique was used to test the effect of pH and the buffering capacity of external bath on Cl(-) and K(+) currents during hypotonic shock. In the presence of a high buffer concentration (30 mM HEPES), the cells did not undergo RVD and did not develop outward K(+) currents (TASK2). Interestingly, the hypotonic shock reduced the cytosolic pH (pH(i)) and increased the external pH (pH(e)) in wild-type but not in cftr (-/-) cells. The inhibitory effect of DIDS suggests that the acidification of pH(i) and the alkalinization of pH(e) induced by hypotonicity in wild-type cells could be due to an exit of HCO(3)(-). In conclusion, these results indicate that Cl(-) influx will be the driving force for HCO(3)(-) exit through the activation of the Cl(-)/HCO(3)(-) exchanger. This efflux of HCO(3)(-) then alkalinizes pH(e), which in turn activates TASK2 channels.

  10. A low-temperature-active alkaline pectate lyase from Xanthomonas campestris ACCC 10048 with high activity over a wide pH range.

    PubMed

    Yuan, Peng; Meng, Kun; Wang, Yaru; Luo, Huiying; Shi, Pengjun; Huang, Huoqing; Tu, Tao; Yang, Peilong; Yao, Bin

    2012-11-01

    Alkaline pectate lyases are favorable for the textile industry. Here, we report the gene cloning and expression of a low-temperature-active alkaline pectate lyase (PL D) from Xanthomonas campestris ACCC 10048. Deduced PL D consists of a putative 27-residue signal peptide and a catalytic domain of 320 residues belonging to family PF09492. Recombinant PL D (r-PL D) produced in Escherichia coli was purified to electrophoretic homogeneity with a single step of Ni(2+)-NTA affinity chromatography and showed an apparent molecular weight of ~38 kDa. The pH and temperature optima of r-PL D were found to be 9.0 °C and 30 °C, respectively. Compared with its microbial counterparts, r-PL D had higher activity over a wide pH range (>45 % of the maximum activity at pH 3.0-12.0) and at lower temperatures (>35 % of activity even at 0 °C). The K(m) and V(max) values of r-PL D for polygalacturonic acid were 4.9 gl(-1) and 30.1 μmolmin(-1) mg(-1), respectively. Compared with the commercial compound pectinase from Novozymes, r-PL D showed similar efficacy in reducing the intrinsic viscosity of polygalacturonic acid (35.1 % vs. 36.5 %) and in bioscouring of jute (10.25 % vs. 10.82 %). Thus, r-PL D is a valuable additive candidate for the textile industry.

  11. Intracellular pH regulates basolateral K+ and Cl- conductances in colonic epithelial cells by modulating Ca2+ activation

    PubMed Central

    1991-01-01

    The role of intracellular pH as a modulator of basolateral K+ and Cl- conductances in epithelial cells was studied using digitonin- permeabilized colonic cell layers so that cytosolic pH could be clamped at specific values, while basolateral K+ and Cl- conductances were activated by stepwise increases in intracellular free Ca2+. Increasing the intracellular pH from 6.6 to 8.0 enhanced the sensitivity of both ionic conductances to intracellular Ca2+, but changing extracellular pH had no effect. Maximal K+ and Cl- currents activated by Ca2+ were not affected by changes in intracellular pH, suggesting that protons do not alter the conduction properties of the channels. Hill analysis of the Ca2+ activation process revealed that raising the cytosolic pH from 6.6 to 8.0 reduced the K1/2 for Ca2+ activation. In the absence of Ca2+, changes in intracellular pH did not have a significant effect on the basolateral K+ and Cl- conductances. These results are consistent with the notion that changes in cytosolic pH can modulate basolateral conductances by modifying the action of calcium, perhaps by acting at or near the activation site to provide a mechanism of variable "gain control." PMID:1719125

  12. On the effect of alkaline pH and cofactor availability in the conformational and oligomeric state of Escherichia coli glutamate decarboxylase.

    PubMed

    Giovannercole, F; Mérigoux, C; Zamparelli, C; Verzili, D; Grassini, G; Buckle, M; Vachette, P; De Biase, D

    2017-01-05

    Escherichia coli glutamate decarboxylase (EcGad) is a homohexameric pyridoxal 5'-phosphate (PLP)-dependent enzyme. It is the structural component of the major acid resistance system that protects E. coli from strong acid stress (pH < 3), typically encountered in the mammalian gastrointestinal tract. In fact EcGad consumes one proton/catalytic cycle while yielding γ-aminobutyrate and carbon dioxide from the decarboxylation of l-glutamate. Two isoforms of Gad occur in E. coli (GadA and GadB) that are 99% identical in sequence. GadB is the most intensively investigated. Prompted by the observation that some transcriptomic and proteomic studies show EcGad to be expressed in conditions far from acidic, we investigated the structural organization of EcGadB in solution in the pH range 7.5-8.6. Small angle X-ray scattering, combined with size exclusion chromatography, and analytical ultracentrifugation analysis show that the compact and entangled EcGadB hexameric structure undergoes dissociation into dimers as pH alkalinizes. When PLP is not present, the dimeric species is the most abundant in solution, though evidence for the occurrence of a likely tetrameric species was also obtained. Trp fluorescence emission spectra as well as limited proteolysis studies suggest that PLP plays a key role in the acquisition of a folding necessary for the canonical catalytic activity.

  13. Catalysis and stability of an alkaline protease from a haloalkaliphilic bacterium under non-aqueous conditions as a function of pH, salt and temperature.

    PubMed

    Pandey, Sandeep; Rakholiya, Kalpna D; Raval, Vikram H; Singh, Satya P

    2012-09-01

    A haloalkaliphilic bacterium, isolated from Coastal Gujarat (India) was identified as Oceanobacillus sp. (GQ162111) based on 16S rRNA gene sequence. The organism grew and secreted extra cellular protease in presence of various organic solvents. At 30% (v/v) concentration of hexane, heptane, isooctane, dodecane and decane, significant growth and protease production was evident. The alkaline protease was purified in a single step on phenyl sepharose 6 FF with 28% yield. The molecular mass as judged by SDS-PAGE was 30 kDa. The temperature optimum of protease was 50°C and the enzyme retained 70% activity in 10% (v/v) isooctane. Effect of salt and pH was investigated in combination to assess the effect of isooctane. In organic solvents, the enzyme was considerably active at pH 8-11, with optimum activity at pH 10. Salt at 2 M was optimum for activity and enzyme maintained significant stability up to 18 h even at 3 M salt concentration. Patters of growth, protease production, catalysis and stability of the enzyme are presented. The study resumes significance as limited information is available on the interaction of haloalkaliphilic bacteria and their enzymes with organic solvents.

  14. Chemical equilibrium model for interfacial activity of crude oil in aqueous alkaline solution: the effects of pH, alkali and salt

    SciTech Connect

    Chan, M.; Yen, T.F.

    1980-11-01

    A chemical equilibrium model for interfacial activity of crude in aqueous alkaline solution is proposed. The model predicts the observed effects of pH and concentrations of alkali and salt on the interfacial tension (IFT). The model proposed was shown to describe the observed effects of acid content, pH, and sodium ions on the interfacial activity of crude oil in water. Once the pH of the interface reaches the pKa of the acids, sometimes with the help of addition of some salt, the IFT experiences a sudden steep drop to the range of 10/sup -2/ dynes/cm. After that, further addition of sodium either in the form of NaOH or NaCl is going to increase the IFT due to a shift of equilibriumn to the formation of undissociated soap. This was confirmed by the difference in the observed effect of sodium on the IFT of the extracted soap molecules which are dissociated easily and those which are associated highly and precipitated easily. These soap molecules have dissociation constant values ranging from below 10/sup -2/ to above one. 13 references.

  15. Growth of Leuconostoc mesenteroides NRRL-B523 in an alkaline medium: suboptimal pH growth inhibition of a lactic acid bacterium.

    PubMed

    Wolf, Barry F; Fogler, H Scott

    2005-01-05

    Bacterial profile modification (BPM), a form of tertiary oil recovery, diverts water from the water-flooded high-permeability zone into the oil-bearing low-permeability zone. During field use, exopolymer-producing bacteria plug the high-permeability zone only in the immediate vicinity of the injection point (the near-well bore region). For effective BPM the plug must penetrate far into the formation. Slowing the specific growth rate, lengthening the lag phase, and slowing the polymerization rate are techniques that can prolong the onset of biopolymer gelation and extend the depth of the biological plug. In batch experiments, the growth of Leuconostoc mesenteroides NRRL-B523 was inhibited by the synergistic effects of high substrate loading and an alkaline pH. Exponential growth was delayed up to 190 h. It was observed that cell division was significantly retarded until the medium pH, reduced by the acid byproducts of fermentation, reached a critical value of 6.79 +/- 0.06. A mathematical model was developed to describe the relationship between specific growth rate, lag time, and medium pH.

  16. Multi-laminated copper nanoparticles deposited on conductive substrates for electrocatalytic oxidation of methanol in alkaline electrolytes

    NASA Astrophysics Data System (ADS)

    Xia, Lun-Peng; Guo, Peng; Wang, Yan; Ding, Shi-Qi; He, Jian-Bo

    2014-09-01

    A simple electrodeposition approach to grow multi-laminated copper particles on two conductive substrates is presented. Morphological and structural characterization was performed using SEM and XRD. The copper crystallites are preferentially oriented with {111} planes parallel to the substrate surfaces, providing an optimum interface for methanol oxidation. There are a large number of edges, corners, and atomic steps around individual multi-laminated nanostructured particles. The excellent electrocatalytic activity of the particles to methanol oxidation in alkaline solutions is demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The presence of the conductive poly(2-amino-5-mercapto-1,3,4-thiadiazole) interlayer between the Cu particles and the carbon paste substrate results in larger specific surface areas of the particles and smaller charge-transfer resistances of methanol oxidation reaction in the lower potential range. Such an anisotropic laminated structure of non-noble metal nanomaterials deserves further investigation for finding a suitable alternative to noble metal-based anodic catalysts in fuel cells.

  17. Determination of the equilibrium formation constants of two U(VI)-peroxide complexes at alkaline pH.

    PubMed

    Meca, S; Martínez-Torrents, A; Martí, V; Giménez, J; Casas, I; de Pablo, J

    2011-08-21

    The formation of uranyl-peroxide complexes was studied at alkaline media by using UV-Visible spectrophotometry and the STAR code. Two different complexes were found at a H(2)O(2)/U(VI) ratio lower than 2. A graphical method was used in order to obtain the formation constants of such complexes and the STAR program was used to refine the formation constants values because of its capacity to treat multiwavelength absorbance data and refining equilibrium constants. The values obtained for the two complexes identified were: UO(2)(2+) + H(2)O(2) + 4OH(-) <−> UO(2)(O(2))(OH)(2)(2-) + 2H(2)O: log β°(1,1,4) = 28.1 ± 0.1 (1). UO(2)(2+) + 2H(2)O(2) + 6OH(-) <−> UO(2)(O(2))(2)(OH)(2)(4-) + 4H(2)O: log β°(1,2,6) = 36.8 ± 0.2 (2). At hydrogen peroxide concentrations higher than 10(-5) mol dm(-3), and in the absence of carbonate, the UO(2)(O(2))(2)(OH)(2)(4-) complex is predominant in solution, indicating the significant peroxide affinity of peroxide ions for uranium and the strong complexes of uranium(VI) with peroxide.

  18. Rhesus glycoprotein and urea transporter genes in rainbow trout embryos are upregulated in response to alkaline water (pH 9.7) but not elevated water ammonia.

    PubMed

    Sashaw, Jessica; Nawata, Michele; Thompson, Sarah; Wood, Chris M; Wright, Patricia A

    2010-03-01

    Recent studies have shown that genes for the putative ammonia transporter, Rhesus glycoproteins (Rh) and the facilitated urea transporter (UT) are expressed before hatching in rainbow trout (Oncorhychus mykiss Walbaum) embryos. We tested the hypothesis that Rh and UT gene expressions are regulated in response to environmental conditions that inhibit ammonia excretion during early life stages. Eyed-up embryos (22 days post-fertilization (dpf)) were exposed to control (pH 8.3), high ammonia (1.70 mmol l(-1) NH4HCO3) and high pH (pH 9.7) conditions for 48h. With exposure to high water ammonia, ammonia excretion rates were reversed, tissue ammonia concentration was elevated by 9-fold, but there were no significant changes in mRNA expression relative to control embryos. In contrast, exposure to high water pH had a smaller impact on ammonia excretion rates and tissue ammonia concentrations, whereas mRNA levels for the Rhesus glycoprotein Rhcg2 and urea transporter (UT) were elevated by 3.5- and 5.6-fold, respectively. As well, mRNAs of the genes for H+ATPase and Na+/H+ exchanger (NHE2), associated with NH3 excretion, were also upregulated by 7.2- and 13-fold, respectively, in embryos exposed to alkaline water relative to controls. These results indicate that the Rhcg2, UT and associated transport genes are regulated in rainbow trout embryos, but in contrast to adults, there is no effect of high external ammonia at this stage of development.

  19. Quantification of the dissolved inorganic carbon species and of the pH of alkaline solutions exposed to CO2 under pressure: a novel approach by Raman scattering.

    PubMed

    Beuvier, Thomas; Calvignac, Brice; Bardeau, Jean-François; Bulou, Alain; Boury, Frank; Gibaud, Alain

    2014-10-07

    Dissolved inorganic carbon (DIC) content of aqueous systems is a key function of the pH, of the total alkanility (TA), and of the partial pressure of CO2. However, common analytical techniques used to determine the DIC content in water are unable to operate under high CO2 pressure. Here, we propose to use Raman spectroscopy as a novel alternative to discriminate and quantitatively monitor the three dissolved inorganic carbon species CO2(aq), HCO3(-), and CO3(2-) of alkaline solutions under high CO2 pressure (from P = 0 to 250 bar at T = 40 °C). In addition, we demonstrate that the pH values can be extracted from the molalities of CO2(aq) and HCO3(-). The results are in very good agreement with those obtained from direct spectrophotometric measurements using colored indicators. This novel method presents the great advantage over high pressure conventional techniques of not using breakable electrodes or reference additives and appears of great interest especially in marine biogeochemistry, in carbon capture and storage and in material engineering under high CO2 pressure.

  20. Development of a selective enterococcus medium based on manganese ion deficiency, sodium azide, and alkaline pH.

    PubMed

    Efthymiou, C J; Joseph, S W

    1974-09-01

    Rogosa broth, without its salt supplement and dissolved in deionized water, was adapted for the selective isolation and enumeration of enterococci. This medium supported good growth of enterococci, but it suppressed growth of other lactic acid bacteria. The sensitivity and specificity of the medium were tested after addition of various increasing concentrations of NaN(3) against known strains of enterococci and other bacteria. Many strains of Streptococcus faecium showed low azide tolerance; optimal growth was obtained at a concentration of 0.01% NaN(3), which totally or partially inhibited unrelated species of lactic acid bacteria. The selectivity of the medium was further increased by pH adjustment to 9.6. Carbonate and Tween 80 were added to overcome partial inhibition of enterococcal growth by the new combination of selective conditions. The final medium was evaluated in agar form in isolations from human and animal feces, polluted water, meat, and dairy products. Counts were obtained after 16 to 17 h of incubation at 37 C. The isolates satisfactorily conformed to the group characteristics of enterococci.

  1. Development of a Selective Enterococcus Medium Based on Manganese Ion Deficiency, Sodium Azide, and Alkaline pH

    PubMed Central

    Efthymiou, C. J.; Joseph, S. W.

    1974-01-01

    Rogosa broth, without its salt supplement and dissolved in deionized water, was adapted for the selective isolation and enumeration of enterococci. This medium supported good growth of enterococci, but it suppressed growth of other lactic acid bacteria. The sensitivity and specificity of the medium were tested after addition of various increasing concentrations of NaN3 against known strains of enterococci and other bacteria. Many strains of Streptococcus faecium showed low azide tolerance; optimal growth was obtained at a concentration of 0.01% NaN3, which totally or partially inhibited unrelated species of lactic acid bacteria. The selectivity of the medium was further increased by pH adjustment to 9.6. Carbonate and Tween 80 were added to overcome partial inhibition of enterococcal growth by the new combination of selective conditions. The final medium was evaluated in agar form in isolations from human and animal feces, polluted water, meat, and dairy products. Counts were obtained after 16 to 17 h of incubation at 37 C. The isolates satisfactorily conformed to the group characteristics of enterococci. Images PMID:4214072

  2. Experimental investigations of the effect the electrical conductivity of medium has on the performance of pH meters

    NASA Astrophysics Data System (ADS)

    Rodionov, A. K.; Karashchuk, S. A.

    2013-07-01

    Results from tests of pH meters carried out in ammonia media having low electric conductivity (less than 5.0 μS/cm) are presented. The check media for the tests were prepared in a special manner the use of which makes it possible to reproduce the pH value of solution with an error not exceeding ˜0.04pH in the range of electrical conductivities above 0.1 μS/cm. The instrument measurement error was determined at different electrical conductivities of medium. Different electrodes were tested, the majority of which were domestically produced ones intended for general industrial applications. Some results were also obtained for one dedicated electrode from a foreign manufacturer. The test results show that the instrument gives a biased pH value for such media. The bias has a random value, which nonetheless is stable in the majority of cases, depends on the electrical conductivity of medium being monitored, and may be quite essential for small electrical conductivities (0.5pH or more). A conclusion is drawn about the need to calibrate the instruments with respect to standard media having electrical conductivity close to that of the medium being monitored. Analytic relations characterizing the check media used fort tests (check solutions) are presented.

  3. pH. Agricultural Lesson Plans.

    ERIC Educational Resources Information Center

    Southern Illinois Univ., Carbondale. Dept. of Agricultural Education and Mechanization.

    This lesson plan is intended for use in conducting classes on the effect of pH on plant growth. Presented first are an attention step/problem statement and a series of questions and answers designed to convey general information about soil pH and its effect on plants. The following topics are among those discussed: acidity and alkalinity; the…

  4. Effects of alkalinity on ammonia removal, carbon dioxide stripping, and system pH in semi-commercial scale water recirculating aquaculture systems operated with moving bed bioreactors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When operating water recirculating systems (RAS) with high make-up water flushing rates in locations that have low alkalinity in the raw water, such as Norway, knowledge about the required RAS alkalinity concentration is important. Flushing RAS with make-up water containing low alkalinity washes out...

  5. Alkaline Cytosolic pH and High Sodium Hydrogen Exchanger 1 (NHE1) Activity in Th9 Cells.

    PubMed

    Singh, Yogesh; Zhou, Yuetao; Shi, Xiaolong; Zhang, Shaqiu; Umbach, Anja T; Salker, Madhuri S; Lang, Karl S; Lang, Florian

    2016-11-04

    CD4(+) T helper 9 (Th9) cells are a newly discovered Th cell subset that produce the pleiotropic cytokine IL-9. Th9 cells can protect against tumors and provide resistance against helminth infections. Given their pivotal role in the adaptive immune system, understanding Th9 cell development and the regulation of IL-9 production could open novel immunotherapeutic opportunities. The Na(+)/H(+) exchanger 1 (NHE1; gene name Slc9α1)) is critically important for regulating intracellular pH (pHi), cell volume, migration, and cell survival. The pHi influences cytokine secretion, activities of membrane-associated enzymes, ion transport, and other effector signaling molecules such as ATP and Ca(2+) levels. However, whether NHE1 regulates Th9 cell development or IL-9 secretion has not yet been defined. The present study explored the role of NHE1 in Th9 cell development and function. Th cell subsets were characterized by flow cytometry and pHi was measured using 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein-acetoxymethyl ester (BCECF-AM) dye. NHE1 functional activity was estimated from the rate of realkalinization following an ammonium pulse. Surprisingly, in Th9 cells pHi and NHE1 activity were significantly higher than in all other Th cell subsets (Th1/Th2/Th17 and induced regulatory T cells (iTregs)). NHE1 transcript levels and protein abundance were significantly higher in Th9 cells than in other Th cell subsets. Inhibition of NHE1 by siRNA-NHE1 or with cariporide in Th9 cells down-regulated IL-9 and ATP production. NHE1 activity, Th9 cell development, and IL-9 production were further blunted by pharmacological inhibition of protein kinase Akt1/Akt2. Our findings reveal that Akt1/Akt2 control of NHE1 could be an important physiological regulator of Th9 cell differentiation, IL-9 secretion, and ATP production.

  6. Tracing of γ-radiation-induced electrical conductivity and pH change of hexamethylenetetramine aqueous solutions and its applications.

    PubMed

    Sife-Eldeen, Kh A

    2013-04-01

    The interest in studying γ-radiation effects on hexamethylenetetramine (HMTA) is due to its importance in nuclear fuel technology. The current study indicates that γ-radiation induces electrical conductivity (RIC) and pH changes in HMTA aqueous solutions. The effects of HMTA concentration, absorbed radiation dose, absorbed dose rate and storage time on RIC and pH changes were studied. HMTA aqueous solutions could be considered as a promising γ-radiation dosimeter, in both technical and medical fields.

  7. Escherichia coli YqjA, a Member of the Conserved DedA/Tvp38 Membrane Protein Family, Is a Putative Osmosensing Transporter Required for Growth at Alkaline pH

    PubMed Central

    Kumar, Sujeet

    2015-01-01

    ABSTRACT The ability to persist and grow under alkaline conditions is an important characteristic of many bacteria. In order to survive at alkaline pH, Escherichia coli must maintain a stable cytoplasmic pH of about 7.6. Membrane cation/proton antiporters play a major role in alkaline pH homeostasis by catalyzing active inward proton transport. The DedA/Tvp38 family is a highly conserved membrane protein family of unknown function present in most sequenced genomes. YqjA and YghB are members of the E. coli DedA family with 62% amino acid identity and partially redundant functions. We have shown that E. coli with ΔyqjA and ΔyghB mutations cannot properly maintain the proton motive force (PMF) and is compromised in PMF-dependent drug efflux and other PMF-dependent functions. Furthermore, the functions of YqjA and YghB are dependent upon membrane-embedded acidic amino acids, a hallmark of several families of proton-dependent transporters. Here, we show that the ΔyqjA mutant (but not ΔyghB) cannot grow under alkaline conditions (ranging from pH 8.5 to 9.5), unlike the parent E. coli. Overexpression of yqjA restores growth at alkaline pH, but only when more than ∼100 mM sodium or potassium is present in the growth medium. Increasing the osmotic pressure by the addition of sucrose enhances the ability of YqjA to support growth under alkaline conditions in the presence of low salt concentrations, consistent with YqjA functioning as an osmosensor. We suggest that YqjA possesses proton-dependent transport activity that is stimulated by osmolarity and that it plays a significant role in the survival of E. coli at alkaline pH. IMPORTANCE The ability to survive under alkaline conditions is important for many species of bacteria. Escherichia coli can grow at pH 5.5 to 9.5 while maintaining a constant cytoplasmic pH of about 7.6. Under alkaline conditions, bacteria rely upon proton-dependent transporters to maintain a constant cytoplasmic pH. The DedA/Tvp38 protein family

  8. The voltage-activated hydrogen ion conductance in rat alveolar epithelial cells is determined by the pH gradient

    PubMed Central

    1995-01-01

    Voltage-activated H+ currents were studied in rat alveolar epithelial cells using tight-seal whole-cell voltage clamp recording and highly buffered, EGTA-containing solutions. Under these conditions, the tail current reversal potential, Vrev, was close to the Nernst potential, EH, varying 52 mV/U pH over four delta pH units (delta pH = pHo - pHi). This result indicates that H+ channels are extremely selective, PH/PTMA > 10(7), and that both internal and external pH, pHi, and pHo, were well controlled. The H+ current amplitude was practically constant at any fixed delta pH, in spite of up to 100-fold symmetrical changes in H+ concentration. Thus, the rate-limiting step in H+ permeation is pH independent, must be localized to the channel (entry, permeation, or exit), and is not bulk diffusion limitation. The instantaneous current- voltage relationship exhibited distinct outward rectification at symmetrical pH, suggesting asymmetry in the permeation pathway. Sigmoid activation kinetics and biexponential decay of tail currents near threshold potentials indicate that H+ channels pass through at least two closed states before opening. The steady state H+ conductance, gH, as well as activation and deactivation kinetic parameters were all shifted along the voltage axis by approximately 40 mV/U pH by changes in pHi or pHo, with the exception of the fast component of tail currents which was shifted less if at all. The threshold potential at which H+ currents were detectably activated can be described empirically as approximately 20-40(pHo-pHi) mV. If internal and external protons regulate the voltage dependence of gH gating at separate sites, then they must be equally effective. A simpler interpretation is that gating is controlled by the pH gradient, delta pH. We propose a simple general model to account for the observed delta pH dependence. Protonation at an externally accessible site stabilizes the closed channel conformation. Deprotonation of this site permits a

  9. High-resolution kinetics of transferrin acidification in BALB/c 3T3 cells: exposure to pH 6 followed by temperature-sensitive alkalinization during recycling.

    PubMed

    Sipe, D M; Murphy, R F

    1987-10-01

    The kinetics of acidification of diferric human transferrin in BALB/c mouse 3T3 cells were determined by flow cytometry using a modification of the fluorescein-rhodamine fluorescence ratio technique. For cells labeled at 0 degrees C and warmed to 37 degrees C, the minimum pH observed was 6.1 +/- 0.2, occurring 5 min after warmup. This step was followed by a slower alkalinization to the pH of the external medium, occurring with a half-time of 5 min. Warmup to 24 degrees C or 17 degrees C resulted in slowing of the time of onset of acidification such that the minimum pH was 6.3 +/- 0.2, attained 15 and 25 min after warmup, respectively; the alkalinization step was completely blocked. The limited acidification observed for transferrin corresponds to the initial phase of acidification normally observed for other (nonrecycled) ligands. Since transferrin is not further acidified, the results confirm the existence of two phases of acidification during endocytosis. Measurements of transferrin dissociation at neutral pH after exposure to mildly acidic pH support the conclusion that the transferrin cycle may be completed without exposure of transferrin to a pH below 6. The mildly acidic pH of the endocytic compartments involved in recycling may play a role in regulating enzymatic processing of endocytosed material.

  10. Soil pH and electrical conductivity are key edaphic factors shaping bacterial communities of greenhouse soils in Korea.

    PubMed

    Kim, Jeong Myeong; Roh, An-Sung; Choi, Seung-Chul; Kim, Eun-Jeong; Choi, Moon-Tae; Ahn, Byung-Koo; Kim, Sun-Kuk; Lee, Young-Han; Joa, Jae-Ho; Kang, Seong-Soo; Lee, Shin Ae; Ahn, Jae-Hyung; Song, Jaekyeong; Weon, Hang-Yeon

    2016-12-01

    Soil microorganisms play an essential role in soil ecosystem processes such as organic matter decomposition, nutrient cycling, and plant nutrient availability. The land use for greenhouse cultivation has been increasing continuously, which involves an intensive input of agricultural materials to enhance productivity; however, relatively little is known about bacterial communities in greenhouse soils. To assess the effects of environmental factors on the soil bacterial diversity and community composition, a total of 187 greenhouse soil samples collected across Korea were subjected to bacterial 16S rRNA gene pyrosequencing analysis. A total of 11,865 operational taxonomic units at a 97% similarity cutoff level were detected from 847,560 sequences. Among nine soil factors evaluated; pH, electrical conductivity (EC), exchangeable cations (Ca(2+), Mg(2+), Na(+), and K(+)), available P2O5, organic matter, and NO3-N, soil pH was most strongly correlated with bacterial richness (polynomial regression, pH: R(2) = 0.1683, P < 0.001) and diversity (pH: R(2) = 0.1765, P < 0.001). Community dissimilarities (Bray-Curtis distance) were positively correlated with Euclidean distance for pH and EC (Mantel test, pH: r = 0.2672, P < 0.001; EC: r = 0.1473, P < 0.001). Among dominant phyla (> 1%), the relative abundances of Proteobacteria, Gemmatimonadetes, Acidobacteria, Bacteroidetes, Chloroflexi, and Planctomycetes were also more strongly correlated with pH and EC values, compared with other soil cation contents, such as Ca(2+), Mg(2+), Na(+), and K(+). Our results suggest that, despite the heterogeneity of various environmental variables, the bacterial communities of the intensively cultivated greenhouse soils were particularly influenced by soil pH and EC. These findings therefore shed light on the soil microbial ecology of greenhouse cultivation, which should be helpful for devising effective management strategies to enhance soil microbial diversity and improving crop productivity.

  11. Systems Characterization of Temperature, Ph and Electrical Conductivity in Aerobic Biodegradation of Wheat Biomass at Differing Mixing Rates

    NASA Technical Reports Server (NTRS)

    Calhoun, M.; Trotman, A.; Aglan, H.

    1998-01-01

    The purpose of this preliminary study is to observe and relate the rate of mixing to pH and electrical conductivity in an aerobic, continuously stirred bioreactor. The objective is to use data collected from successive experiments as a means of a system characterization. Tests were conducted to obtain these data using a continuously stirred 20 L Cytostir glass reaction vessel as a bioreactor operated without built-in temperature or pH control. The tests were conducted on the lab bench at ambient temperatures. The substrate in the bioreactor was ground wheat biomass obtained from the Biomass Production Chamber at NASA Kennedy Space Center. In this study, the data reflect characteristics of the native (uninoculated) systems as well as inoculated systems. In the native systems, it was found that pi levels became stable after approximately 2 to 3 days. The electrical conductivity levels for the native systems tended to decrease over time. In contrast, ion activity was increased after the introduction of bacteria into the system. This could be correlated with the release of nutrients, due to the activity of the bacteria. Also, there were slight increases in pH in the inoculated system, a result which is expected for a system with no active pr controls. The data will be used to test a mathematical model in an automated system.

  12. Overexpression of the cystic fibrosis transmembrane conductance regulator in NIH 3T3 cells lowers membrane potential and intracellular pH and confers a multidrug resistance phenotype.

    PubMed Central

    Wei, L Y; Stutts, M J; Hoffman, M M; Roepe, P D

    1995-01-01

    Because of the similarities between the cystic fibrosis transmembrane conductance regulator (CFTR) and multidrug resistance (MDR) proteins, recent observations of decreased plasma membrane electrical potential (delta psi) in cells overexpressing either MDR protein or the CFTR, and the effects of delta psi on passive diffusion of chemotherapeutic drugs, we have analyzed chemotherapeutic drug resistance for NIH 3T3 cells overexpressing different levels of functional CFTR. Three separate clones not previously exposed to chemotherapeutic drugs exhibit resistance to doxorubicin, vincristine, and colchicine that is similar to MDR transfectants not previously exposed to chemotherapeutic drugs. Two other clones expressing lower levels of CFTR are less resistant. As shown previously these clones exhibit decreased plasma membrane delta psi similar to MDR transfectants, but four of five exhibit mildly acidified intracellular pH in contrast to MDR transfectants, which are in general alkaline. Thus the MDR protein and CFTR-mediated MDR phenotypes are distinctly different. Selection of two separate CFTR clones on either doxorubicin or vincristine substantially increases the observed MDR and leads to increased CFTR (but not measurable MDR or MRP) mRNA expression. CFTR overexpressors also exhibit a decreased rate of 3H -vinblastine uptake. These data reveal a new and previously unrecognized consequence of CFTR expression, and are consistent with the hypothesis that membrane depolarization is an important determinant of tumor cell MDR. Images FIGURE 1 FIGURE 3 FIGURE 6 PMID:8519988

  13. An analytical relationship between the magnetospheric potential drop and the ionospheric conductance. Ph.D. Thesis

    SciTech Connect

    Krisko, P.H.

    1994-01-01

    In this thesis the author derives an analytical relationship between the Earth`s magnetospheric potential drop and the ionospheric conductance by adopting a simple two-dimensional model of a magnetic field draping around the tail magnetopause. Two methods are used: (1) matching currents through the tail magnetopause and the Earth`s ionosphere in analogy with the Alfven wing at the Jovian satellite, Io; and (2) minimizing the total power that the solar wind loses to the Earth`s magnetosphere. The author finds, in both cases, the magnetospheric conductance, Sigma(sub is), and compares this result to the revised result of the numerical model of Fedder and Lyon and to the conclusions of Hill et al. and Hill. Considering the derived proportionality factor as a `magnetosheath conductance`, Sigma(sub msh), the author determines that the high-latitude tail magnetospheric `driver` acts as a current generator as opposed to a voltage generator.

  14. Continuous pH, electrical conductivity and temperature measurement at Plynlimon: towards an integrated, reliable and low maintenance instrument system

    NASA Astrophysics Data System (ADS)

    Hodgson, P.; Evans, J. G.

    Water quality data for the Nant Tanilwyth stream, Plynlimon (an acidic upland stream, the waters of which are of such low ionic strength that measurement is difficult), has been recorded using a new integrated field instrument system. The negligible drift of the pH electrode allows the system to operate for extended periods (months) without re-calibration, whilst maintaining a standard deviation of 0.19 pH units between its readings and laboratory reference measurements. Conductivity measurements, although within the sensor manufacturer's specification, did not provide meaningful readings at conductivities below 50 μS cm-1. Using the pH data as a surrogate tracer, a high temporal resolution estimate of the stream dynamics, in terms of the contributions of groundwater and soil-water is presented; the dependence of these relative proportions on instantaneous flow and antecedent conditions is shown. It is concluded that, whilst improvements in instrumentation have been made, greater accuracy is still desirable for some scientific applications and ways forward are described.

  15. Rapid solidification of high-conductivity copper alloys. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Bloom, Theodore Atlas

    1989-01-01

    The main objective was to develop improved copper alloys of high strength and high thermal and electric conductivity. Chill block melt spinning was used to produce binary alloys of Cu-Cr and Cu-Zr, and ternary alloys of Cu-Cr-Ag. By quenching from the liquid state, up to 5 atomic percent of Cr and Zr were retained in metastable extended solid solution during the rapid solidification process. Eutectic solidification was avoided and the full strengthening benefits of the large volume fraction of precipitates were realized by subsequent aging treatment. The very low solid solubility of Cr and Zr in Cu result in a high conductivity Cu matrix strengthened by second phase precipitates. Tensile properties on as-cast and aged ribbons were measured at room and elevated temperatures. Precipitate coarsening of Cr in Cu was studied by changes in electrical resistance during aging. X-ray diffraction was used to measure the lattice parameter and the degree of supersaturation of the matrix. The microstructures were characterized by optical and electron microscopy.

  16. Effect of pH on the electrical properties and conducting mechanism of SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Periathai, R. Sudha; Abarna, S.; Hirankumar, G.; Jeyakumaran, N.; Prithivikumaran, N.

    2017-03-01

    Semiconductor nanoparticles have attracted more interests because of their size-dependent optical and electrical properties.SnO2 is an oxygen-deficient n-type semiconductor with a wide band gap of 3.6 eV (300 K). It has many remarkable applications as sensors, catalysts, transparent conducting electrodes, anode material for rechargeable Li- ion batteries and optoelectronic devices. In the present work, the role of pH in determining the electrical and dielectric properties of SnO2 nanoparticles has been studied as a function of temperature ranging from Room temperature (RT) to 114 °C in the frequency range of 7 MHz to 50 mHz using impedance spectroscopic technique. The non linear behavior observed in the thermal dependence of the conductance of SnO2 nanoparticles is explained by means of the surface property of SnO2 nanoparticles where proton hopping mechanism is dealt with. Jonscher's power law has been fitted for the conductance spectra and the frequency exponent ("s" value) gives an insight about the ac conducting mechanism. The temperature dependence of electrical relaxation phenomenon in the material has been observed. The complex electric modulus analysis indicates the possibility of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation.

  17. Effect of external and internal pH changes on K and Cl conductances in the muscle fiber membrane of a giant barnacle.

    PubMed

    Hagiwara, S; Gruener, R; Hayashi, H; Sakata, H; Grinnell, A D

    1968-11-01

    The membrane potential and conductance of the giant muscle fiber of a barnacle (Balanus nubilus Darwin) were analyzed in relation to changes in the external (3.5-10.0) and the internal (4.7-9.6) pH, under various experimental conditions. A sharp increase in membrane conductance, associated with a large increase in conductance to Cl ions, was observed when the external pH was lowered to values below 5.0. The ratio of Cl to K conductance in normal barnacle saline is between (1/6)-1/7 at pH 7.7, whereas at pH 4.0 the ratio is about 6-9. The behavior of the membrane in response to pH changes in a Cl-depleted muscle fiber shows that the K conductance decreases with decreasing external pH for the whole range of pH examined. A steep increase in Cl conductance is also observed when the internal pH of the fiber is lowered below 5.0. The K to Cl conductance ratio increases with increasing internal pH in a manner very similar to that found when the external pH is raised above 5.0. These facts suggest that the membrane is amphoteric with positive and negative fixed charge groups having dissociation constants such that at pH greater than 5, negative groups predominate and cations permeate more easily than anions, while at lower pH positive groups predominate, facilitating the passage of anions through the membrane.

  18. Microchannel conductivity measurements in microchip for on line monitoring of dephosphorylation rates of organic phosphates using paramagnetic-beads linked alkaline phosphatase.

    PubMed

    Kechadi, Mohammed; Sotta, Bruno; Gamby, Jean

    2015-01-01

    This paper presents the use of polymer coated microelectrodes for the realtime conductivity monitoring in a microchannel photoablated through the polymer without contact. Based on this strategy, a small conductometry sensor has been developed to record in time conductivity variation when an enzymatic reaction occurs through the channel. The rate constant determination, k2, for the dephosphorylation of organic phosphate-alkaline phosphatase-superparamagnetic beads complex using chemically different substrates such as adenosine monoesterphosphate, adenosine diphosphate and adenosine triphosphate was taken as an example to demonstrate selectivity and sensivity of the detection scheme. The k2 value measured for each adenosine phosphate decreases from 39 to 30 s(-1) in proportion with the number (3, 2 and 1) of attached phosphate moiety, thus emphasizing the steric hindrance effect on kinetics.

  19. New Secondary Batteries Utilizing Electronically Conductive Polypyrrole Cathode. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Yeu, Taewhan

    1991-01-01

    To gain a better understanding of the dynamic behavior in electronically conducting polypyrroles and to provide guidance toward designs of new secondary batteries based on these polymers, two mathematical models are developed; one for the potentiostatically controlled switching behavior of polypyrrole film, and one for the galvanostatically controlled charge/discharge behavior of lithium/polypyrrole secondary battery cell. The first model is used to predict the profiles of electrolyte concentrations, charge states, and electrochemical potentials within the thin polypyrrole film during switching process as functions of applied potential and position. Thus, the detailed mechanisms of charge transport and electrochemical reaction can be understood. Sensitivity analysis is performed for independent parameters, describing the physical and electrochemical characteristic of polypyrrole film, to verify their influences on the model performance. The values of independent parameters are estimated by comparing model predictions with experimental data obtained from identical conditions. The second model is used to predict the profiles of electrolyte concentrations, charge state, and electrochemical potentials within the battery system during charge and discharge processes as functions of time and position. Energy and power densities are estimated from model predictions and compared with existing battery systems. The independent design criteria on the charge and discharge performance of the cell are provided by studying the effects of design parameters.

  20. Deletions of endocytic components VPS28 and VPS32 affect growth at alkaline pH and virulence through both RIM101-dependent and RIM101-independent pathways in Candida albicans.

    PubMed

    Cornet, Muriel; Bidard, Frédérique; Schwarz, Patrick; Da Costa, Grégory; Blanchin-Roland, Sylvie; Dromer, Françoise; Gaillardin, Claude

    2005-12-01

    Ambient pH signaling involves a cascade of conserved Rim or Pal products in ascomycetous yeasts or filamentous fungi, respectively. Recent evidences in the fungi Aspergillus nidulans, Saccharomyces cerevisiae, Yarrowia lipolytica, and Candida albicans suggested that components of endosomal sorting complexes required for transport (ESCRT) involved in endocytic trafficking were needed for signal transduction along the Rim pathway. In this study, we confirm these findings with C. albicans and show that Vps28p (ESCRT-I) and Vps32p/Snf7p (ESCRT-III) are required for the transcriptional regulation of known targets of the Rim pathway, such as the PHR1 and PHR2 genes encoding cell surface proteins, which are expressed at alkaline and acidic pH, respectively. We additionally show that deletion of these two VPS genes, particularly VPS32, has a more drastic effect than a RIM101 deletion on growth at alkaline pH and that this effect is only partially suppressed by expression of a constitutively active form of Rim101p. Finally, in an in vivo mouse model, both vps null mutants were significantly less virulent than a rim101 mutant, suggesting that VPS28 and VPS32 gene products affect virulence both through Rim-dependent and Rim-independent pathways.

  1. In-line application of electric field in capillary separation systems: Joule heating, pH and conductivity.

    PubMed

    Eriksson, Björn O; Skuland, Inger Lill; Marlin, Nicola D; Andersson, Magnus B O; Blomberg, Lars G

    2008-03-15

    This study concerns the technique electric field-assisted capillary liquid chromatography. In this technique, an electric field is applied over the separation capillary in order to provide an additional selectivity. In this technique, the electric field is applied in-line in the separation capillary and here the electric current is the factor limiting the magnitude of applied electric field. The influence of Joule heating and other factors on the current in such systems has been investigated. The temperature in the capillary was first measured within a standard CE set-up, as function of effect per unit of length. Then the same cooling system was applied to an in-line set-up, to replicate the conditions between the two systems, and thus the temperature. Thus Joule heating effects could then be calculated within the in-line system. It was found that for systems applying an electric field in line, the direct influence from Joule heating was only relatively small. The pH in the capillary was measured in the in-line set-up using cresol red/TRIS solutions as pH probe. Significant changes in pH were observed and the results suggested that electrolysis of water is the dominant electrode reaction in the in-line system. In summary, the observed conductivity change in in-line systems was found to be mainly due to the pH change by hydrolysis of water, but primarily not due the temperature change in the capillary column.

  2. Continuous bioproduction of short-chain fatty acids from sludge enhanced by the combined use of surfactant and alkaline pH.

    PubMed

    Chen, Yinguang; Liu, Kun; Su, Yinglong; Zheng, Xiong; Wang, Qin

    2013-07-01

    This work reported the enhancement of continuous SCFA production from sludge by the combined use of surfactant (sodium dodecylbenzene sulfonate (SDBS)) and pH 10 (i.e., SDBS & pH 10). The maximal SCFA production (2056 mg COD/L) was achieved under the SDBS & pH 10 condition at a sludge retention time (SRT) of 12d, which was much higher than that of the blank, sole SDBS, or pH 10. The mechanisms investigation showed that the combined strategy had greater sludge solubilization, higher protein hydrolysis, and lower activity of methanogens. Fluorescence in situ hybridization analysis revealed that the abundance of bacteria was increased, whereas that of archaea was decreased by SDBS & pH 10. The excitation emission matrix fluorescence spectroscopy assay further suggested that SBDS caused protein structure change, which benefited protein hydrolysis.

  3. Spatial models to predict ash pH and Electrical Conductivity distribution after a grassland fire in Lithuania

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Cerda, Artemi; Misiūnė, Ieva

    2015-04-01

    Fire mineralizes the organic matter, increasing the pH level and the amount of dissolved ions (Pereira et al., 2014). The degree of mineralization depends among other factors on fire temperature, burned specie, moisture content, and contact time. The impact of wildland fires it is assessed using the fire severity, an index used in the absence of direct measures (e.g temperature), important to estimate the fire effects in the ecosystems. This impact is observed through the loss of soil organic matter, crown volume, twig diameter, ash colour, among others (Keeley et al., 2009). The effects of fire are highly variable, especially at short spatial scales (Pereira et al., in press), due the different fuel conditions (e.g. moisture, specie distribution, flammability, connectivity, arrangement, etc). This variability poses important challenges to identify the best spatial predictor and have the most accurate spatial visualization of the data. Considering this, the test of several interpolation methods it is assumed to be relevant to have the most reliable map. The aims of this work are I) study the ash pH and Electrical Conductivity (EC) after a grassland fire according to ash colour and II) test several interpolation methods in order to identify the best spatial predictor of pH and EC distribution. The study area is located near Vilnius at 54.42° N and 25.26°E and 154 ma.s.l. After the fire it was designed a plot with a 27 x 9 m space grid. Samples were taken every 3 meters for a total of 40 (Pereira et al., 2013). Ash color was classified according to Úbeda et al. (2009). Ash pH and EC laboratory analysis were carried out according to Pereira et al. (2014). Previous to data comparison and modelling, normality and homogeneity were assessed with the Shapiro-wilk and Levene test. pH data respected the normality and homogeneity, while EC only followed the Gaussian distribution and the homogeneity criteria after a logarithmic transformation. Data spatial correlation was

  4. Preparing alkaline anion exchange membrane with enhanced hydroxide conductivity via blending imidazolium-functionalized and sulfonated poly(ether ether ketone)

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Jiang, Zhongyi; Tian, Huimin; Wang, Siwen; Zhang, Bei; Cao, Ying; He, Guangwei; Li, Zongyu; Wu, Hong

    2015-08-01

    The development of alkaline anion exchange membrane (AEM) with both high ion conductivity and stabilities is of great significance for fuel cell applications. In this study, a facile acid-base blending method is designed to improve AEM performances. Basic imidazolium-functionalized poly (ether ether ketone) with a high functionalization degree is employed as polymer matrix to pursue high ion-exchange capacity (IEC) as well as high hydroxide conductivity, meanwhile acidic sulfonated poly (ether ether ketone) (SPEEK) is employed as the cross-linking agent to enhance the stabilities of the blend membranes. Particularly, an in-situ Menshutkin/crosslinking method is exploited to prevent the flocculation in the preparation process of blend membranes. As a result, dense and defect-free blend membranes are obtained. The blend membranes exhibit high level of IEC up to 3.15 mmol g-1, and consequently possess elevated hydroxide conductivity up to 31.59 mS cm-1 at 30 °C. In addition, benefiting from the strong electrostatic interaction introduced by the acid-base blending, the stabilities and methanol resistance of blend membranes are enhanced.

  5. Anion conductive aromatic block copolymers containing diphenyl ether or sulfide groups for application to alkaline fuel cells.

    PubMed

    Yokota, Naoki; Ono, Hideaki; Miyake, Junpei; Nishino, Eriko; Asazawa, Koichiro; Watanabe, Masahiro; Miyatake, Kenji

    2014-10-08

    A novel series of aromatic block copolymers composed of fluorinated phenylene and biphenylene groups and diphenyl ether (QPE-bl-5) or diphenyl sulfide (QPE-bl-6) groups as a scaffold for quaternized ammonium groups is reported. The block copolymers were synthesized via aromatic nucleophilic substitution polycondensation, chloromethylation, quaternization, and ion exchange reactions. The block copolymers were soluble in organic solvents and provided thin and bendable membranes by solution casting. The membranes exhibited well-developed phase-separated morphology based on the hydrophilic/hydrophobic block copolymer structure. The membranes exhibited mechanical stability as confirmed by DMA (dynamic mechanical analyses) and low gas and hydrazine permeability. The QPE-bl-5 membrane with the highest ion exchange capacity (IEC = 2.1 mequiv g(-1)) exhibited high hydroxide ion conductivity (62 mS cm(-1)) in water at 80 °C. A noble metal-free fuel cell was fabricated with the QPE-bl-5 as the membrane and electrode binder. The fuel cell operated with hydrazine as a fuel exhibited a maximum power density of 176 mW cm(-2) at a current density of 451 mA cm(-2).

  6. An evaluation of in-situ measurements of water temperature, specific conductance, and pH in low ionic strength streams

    USGS Publications Warehouse

    Ranalli, A.J.

    1998-01-01

    Survey for continuous measurement of water temperature, specific conductance, and pH in four low ionic strength streams in the Catskill Mountains of New York was evaluated through a calculation of their bias, precision, and accuracy and by comparison with laboratory measurements of specific conductance and pH on samples collected concurrently. Results indicate that the mini-monitor measurements of specific conductance and pH in an acidic stream (acid-neutralizing capacity always less than 0) agreed with laboratory measurements well enough that the minimonitors can be used to supplement laboratory measurements (mean difference in pH was 0.02 pH unit and mean difference in specific conductance was 0.72 ??S cm-1. This mean difference was 0.32 ??S cm-1 if the minimonitor data were adjusted by the bias). In less acidic streams (two streams in which the acid-neutralizing capacity was always greater than 0 and one in which the acid-neutralizing capacity was greater than 0 except during high flows), there was poor agreement between laboratory and minimonitor measurements of specific conductance at high flows and pH at all flows. The water-temperature probes measured with sufficiently small bias (-0.1 ??C) and adequate precision (??0.70 ??C) for use with most applications.

  7. Evaluating the role of metal ions in the bathochromic and hyperchromic responses of cyanidin derivatives in acidic and alkaline pH.

    PubMed

    Sigurdson, G T; Robbins, R J; Collins, T M; Giusti, M M

    2016-10-01

    In many food products, colorants derived from natural sources are increasingly popular due to consumer demand. Anthocyanins are one class of versatile and abundant naturally occurring chromophores that produce different hues in nature, especially with metal ions and other copigments assisting. The effects of chelation of metal ions (Mg(2+), Al(3+), Cr(3+), Fe(3+), and Ga(3+)) in factorial excesses to anthocyanin concentration (0-500×) on the spectral characteristics (380-700nm) of cyanidin and acylated cyanidin derivatives were evaluated to better understand the color evolution of anthocyanin-metal chelates in pH 3-8. In all pH, anthocyanins exhibited bathochromic and hyperchromic shifts. Largest bathochromic shifts most often occurred in pH 6; while largest hyperchromic shifts occurred in pH 5. Divalent Mg(2+) showed no observable effect on anthocyanin color while trivalent metal ions caused bathochromic shifts and hue changes. Generally, bathochromic shifts on anthocyanins were greatest with more electron rich metal ions (Fe(3+)≈Ga(3+)>Al(3+)>Cr(3+)).

  8. Effect of pH and temperature on stability and kinetics of novel extracellular serine alkaline protease (70 kDa).

    PubMed

    Bhunia, Biswanath; Basak, Bikram; Mandal, Tamal; Bhattacharya, Pinaki; Dey, Apurba

    2013-03-01

    A novel extracellular serine protease (70 kDa by SDS-PAGE) was purified and characterized. This enzyme retained more than 93% of its initial activity after preincubation for 30 min at 37 °C in the presence of 25% (v/v) tested organic solvents and showed feather degradation activity. The purified enzyme was deactivated at various combinations of pH and temperature to examine the interactive effect of them on enzyme activity. The deactivation process was modeled as first-order kinetics and the deactivation rate constant (k(d)) was found to be minimum at pH 9 and 37 °C. The kinetic analysis of enzyme over a range of pH values indicated two pK values at 6.21 and at 10.92. The lower pK value was likely due to the catalytic histidine in the free enzyme and higher pK value likely reflected deprotonation of the proline moiety of the substrate but ionization of the active site serine is another possibility. Inhibition kinetic showed that enzyme is serine protease because enzyme was competitively inhibited by antipain and aprotinin as these compounds are known to be competitive inhibitors of serine protease. The organic solvent, thermal and pH tolerances of enzyme suggested that it may have potential for use as a biocatalyst in industry.

  9. A monitor for continuous measurement of temperature, pH, and conductance of wet precipitation: Preliminary results from the Adirondack Mountains, New York

    USGS Publications Warehouse

    Johnsson, P.A.; Reddy, M.M.

    1990-01-01

    This report describes a continuous wet-only precipitation monitor designed by the U.S. Geological Survey to record variations in rainfall temperature, pH, and specific conductance at 1-min intervals over the course of storms. Initial sampling in the Adirondack Mountains showed that rainfall acidity varied over the course of summer storms, with low initial pH values increasing as storm intensity increased.This report describes a continuous wet-only precipitation monitor designed by the U.S. Geological Survey to record variations in rainfall temperature, pH, and specific conductance at 1-min intervals over the course of storms. Initial sampling in the Adirondack Mountains showed that rainfall acidity varied over the course of summer storms, with low initial pH values increasing as storm intensity increased.

  10. Solar light (hv) and H2O2/hv photo-disinfection of natural alkaline water (pH 8.6) in a compound parabolic collector at different day periods in Sahelian region.

    PubMed

    Ndounla, J; Pulgarin, C

    2015-11-01

    The photo-disinfection of natural alkaline surface water (pH 8.6 ± 0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10(4) CFU/ml) and Salmonella spp. (10(4) CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H2O2). The addition of H2O2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H2O2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photo-disinfection processes (hv and H2O2/hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO2(-), NO3(-), NH4(+), HPO4(2-), and bicarbonate (HCO3(-))) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested.

  11. Isolated secretion granules from parotid glands of chronically stimulated rats possess an alkaline internal pH and inward-directed H/sup +/ pump activity

    SciTech Connect

    Arvan, P.; Castle, J.D.

    1986-10-01

    Secretion granules have been isolated from the parotid glands of rats that have been chronically stimulated with the ..beta..-adrenergic agonist, isoproterenol. These granules are of interest because they package a quantitatively different set of secretory proteins in comparison with granules from the normal gland. Polypeptides enriched in proline, glycine, and glutamine, which are known to have pI's >10, replace ..cap alpha..-amylase (pI's = 6.8) as the principal content species. The internal pH of granules from the treated rats changes from 7.8 in a potassium sulfate medium to 6.9 in a choline chloride medium. The increased pH over that of normal parotid granules (approx.6.8) appears to protect the change in composition of the secretory contents. Whereas normal mature parotide granules have practically negligible levels of H/sup +/ pumping ATPase activity, the isolated granules from isoproterenol-treated rats undergo a time-dependent internal acidification that requires the presence of ATP and is abolished by an H/sup +/ ionophore. Additionally, an inside-positive granule transmembrane potential develops after ATP addition that depends upon ATP hydrolysis. Two independent methods have been used that exclude the possibility that contaminating organelles are the source of the H/sup +/-ATPase activity. Together these data provide clear evidence for the presence of an H/sup +/ pump in the membranes of parotid granules from chronically stimulated rats. However, despite the presence of H/sup +/-pump activity, fluorescence microscopy with the weak base, acridine orange, reveals that the intragranular pH in live cells is greater than that of the cytoplasm.

  12. Anaerobic methanethiol degradation and methanogenic community analysis in an alkaline (pH 10) biological process for liquefied petroleum gas desulfurization.

    PubMed

    van Leerdam, Robin C; Bonilla-Salinas, Monica; de Bok, Frank A M; Bruning, H; Lens, Piet N L; Stams, Alfons J M; Janssen, Albert J H

    2008-11-01

    Anaerobic methanethiol (MT) degradation by mesophilic (30 degrees C) alkaliphilic (pH 10) communities was studied in a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor inoculated with a mixture of sediments from the Wadden Sea (The Netherlands), Soap Lake (Central Washington), and Russian soda lakes. MT degradation started after 32 days of incubation. During the first 252 days, complete degradation was achieved till a volumetric loading rate of 7.5 mmol MT/L/day, and sulfide, methane, and carbon dioxide were the main reaction products. Temporary inhibition of MT degradation occurred after MT peak loads and in the presence of dimethyl disulfide (DMDS), which is the autooxidation product of MT. From day 252 onwards, methanol was dosed to the reactor as co-substrate at a loading rate of 3-6 mmol/L/day to stimulate growth of methylotrophic methanogens. Methanol was completely degraded and also a complete MT degradation was achieved till a volumetric loading rate of 13 mmol MT/L/day (0.77 mmol MT/gVSS/day). However, from day 354 till the end of the experimental run (day 365), acetate was formed and MT was not completely degraded anymore, indicating that methanol-degrading homoacetogenic bacteria had partially outcompeted the methanogenic MT-degrading archea. The archeal community in the reactor sludge was analyzed by DGGE and sequencing of 16S rRNA genes. The methanogenic archea responsible for the degradation of MT in the reactor were related to Methanolobus oregonensis. A pure culture, named strain SODA, was obtained by serial dilutions in medium containing both trimethyl amine and dimethyl sulfide (DMS). Strain SODA degraded MT, DMS, trimethyl amine, and methanol. Flow sheet simulations revealed that for sufficient MT removal from liquefied petroleum gas, the extraction and biological degradation process should be operated above pH 9.

  13. K[subscript a] and K[subscript b] from pH and Conductivity Measurements: A General Chemistry Laboratory Exercise

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; Moehring, Michael; Arthasery, Phyllis; Barlag, Rebecca

    2011-01-01

    The acid ionization constant, K[subscript a], of acetic acid and the base ionization constant, K[subscript b], of ammonia are determined easily and rapidly using a datalogger, a pH sensor, and a conductivity sensor. To decrease sample preparation time and to minimize waste, sequential aliquots of a concentrated standard are added to a known volume…

  14. Significant different conductivities of the two grades of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), Clevios P and Clevios PH1000, arising from different molecular weights.

    PubMed

    Xia, Yijie; Ouyang, Jianyong

    2012-08-01

    Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is promising to be the next-generation transparent electrode of optoelectronic devices. This paper reports the differences between two commercially available grades of PEDOT:PSS: Clevios P and Clevios PH1000. The as-prepared PEDOT:PSS films from Clevios P and Clevios PH1000 solutions have close conductivities of 0.2-0.35 S cm(-1). Their conductivities can be enhanced to 171 and 1164 S cm(-1), respectively, through a treatment with hydrofluoroacetone trihydrate (HFA). The differences between Clevios P and Clevios PH1000 were studied by various characterizations on PEDOT:PSS aqueous solutions and PEDOT:PSS films. The gel particles are larger in Clevios PH1000 solution than in Clevios P solution as revealed by dynamic light scattering and fluorescence spectroscopy of pyrene in these solutions. These results suggest that PEDOT of Clevios PH1000 has a higher average molecular weight than that of Clevios P. The difference in the molecular weight of PEDOT for the two grades of PEDOT:PSS is confirmed by the characterizations on their polymer films, including atomic force microscopy and temperature dependences of the resistances of as-prepared and HFA-treated PEDOT:PSS films. The different molecular weights of PEDOT also gives rise to significant differences in the electrochemical behaviors of the two grades of PEDOT:PSS, as revealed by the cyclic voltammetry, in situ UV-vis-NIR absorption spectroscopy and potentiostatic transient measurements.

  15. Solid / solution interaction: The effect of carbonate alkalinity on adsorbed thorium

    NASA Astrophysics Data System (ADS)

    LaFlamme, Brian D.; Murray, James W.

    1987-02-01

    Elevated activities of dissolved Th have been found in Soap Lake, an alkaline lake in Eastern Washington. Dissolved 232Th ranges from less than 0.001 to 4.9 dpm/L compared to about 1.3 × 10 -5 dpm/ L in sea water. The enhanced activity in the lake coincides with an increase in carbonate alkalinity. Experiments were conducted to evaluate the effect of pH, ionic strength and carbonate alkalinity on Th adsorption on goethite. Thorium (10 -13 M total) in the presence of 5.22 mg/L α-FeOOH and 0.1 M NaNO 3 has an adsorption edge from pH 2-5. At pH 9.0 ± 0.6 the percent Th absorbed on the solid began to decrease from 100% at 100 meq/L carbonate alkalinity and exhibited no adsorption above 300 meq/L. The experimental data were modeled to obtain the intrinsic adsorption equilibrium constants for Th hydrolysis species. These adsorption constants were incorporated in the model to interpret the observed effect of carbonate alkalinity on Th adsorption. There are two main effects of the alkalinity. To a significant degree the decrease in Th adsorption is due to competition of HCO -3 and CO 2-3 ions for surface sites. Dissolved Th carbonate complexes also contribute to the increase of Th in solution.

  16. A variable stoichiometry model for pH homeostasis in bacteria.

    PubMed Central

    Macnab, R M; Castle, A M

    1987-01-01

    The composition of the proton-motive force of a hypothetical bacterial cell of wide pH tolerance is analyzed according to a model whereby the electron transport chain and various proton-linked sodium and potassium ion transporting modes are responsible for the development of the membrane potential and the chemical potentials of the three cations. Simultaneous use of two or more modes employing the same metal cation, but at a different stoichiometric ratio with respect to protons, produces nonintegral stoichiometry; the modes could represent either different devices or different states of a single device. Cycling of the cation, driven by proton-motive force, results. The relative conductances of the various modes are postulated to be pH-dependent. The pattern of potentials that results is qualitatively in accord with current knowledge and may reflect the mechanism of pH homeostasis in bacteria. The membrane potential is outwardly directed (positive inside) at extremely acid pH, becoming inwardly directed as the pH increases; the pH gradient across the membrane is large and inwardly directed (alkaline inside) at acid pH, becoming smaller and eventually inverting at alkaline pH values; the transmembrane potassium gradient is outwardly directed (high concentration inside) at all pH values; the transmembrane sodium gradient is inwardly directed at all pH values, following the pH gradient from acid through neutral pH, but then diverging at alkaline pH. PMID:3676443

  17. Alkaline flooding injection strategy

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1992-03-01

    The objective of this project is to improved alkali-surfactant flooding methods, and this includes determining the proper design of injection strategy. Several different injection strategies have been used or suggested for recovering heavy oils with surfactant-enhanced alkaline flooding methods. Oil recovery was compared for four different injection strategies: (1) surfactant followed by polymer, (2) surfactant followed by alkaline polymer, (3) alkaline surfactant followed by polymer, and (4) alkali, surfactant, and polymer mixed in a single formulation. The effect of alkaline preflush was also studied under two different conditions. All of the oil recovery experiments were conducted under optimal conditions with a viscous, non-acidic oil from Hepler (KS) oil field. The coreflood experiments were conducted with Berea sandstone cores since field core was not available in sufficient quantity for coreflood tests. The Tucker sand of Hepler field is a Class I fluvial dominated deltaic reservoir, as classified by the Department of Energy, which has been selected as the site of a DOE-sponsored field pilot test.

  18. The electrical conductivity of the Earth's upper mantle as estimated from satellite measured magnetic field variations. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Didwall, E. M.

    1981-01-01

    Low latitude magnetic field variations (magnetic storms) caused by large fluctuations in the equatorial ring current were derived from magnetic field magnitude data obtained by OGO 2, 4, and 6 satellites over an almost 5 year period. Analysis procedures consisted of (1) separating the disturbance field into internal and external parts relative to the surface of the Earth; (2) estimating the response function which related to the internally generated magnetic field variations to the external variations due to the ring current; and (3) interpreting the estimated response function using theoretical response functions for known conductivity profiles. Special consideration is given to possible ocean effects. A temperature profile is proposed using conductivity temperature data for single crystal olivine. The resulting temperature profile is reasonable for depths below 150-200 km, but is too high for shallower depths. Apparently, conductivity is not controlled solely by olivine at shallow depths.

  19. The Bulk Lunar Electrical Conductivity. Ph.D. Thesis. Final Report; [from Explorer 35 satellite and the Apollo 12 flight

    NASA Technical Reports Server (NTRS)

    Leavy, Donald Lucien

    1975-01-01

    The electrical conductivity structure was studied of a spherically layered moon consistent with the very low frequency magnetic data collected on the lunar surface and by Explorer 35. In order to obtain good agreement with the lunar surface magnetometer observations, the inclusion of a void cavity behind the moon requires a conductivity at shallow depths higher than that of models having the solar wind impinging on all sides. By varying only the source parameters, a conductivity model can be found that yields a good fit to both the tangential response upstream and the radial response downstream. This model also satisfies the dark side tangential response in the frequency range above 0.006 Hz, but the few data points presently available below this range do not seem to agree with the theory.

  20. Technetium recovery from high alkaline solution

    DOEpatents

    Nash, Charles A.

    2016-07-12

    Disclosed are methods for recovering technetium from a highly alkaline solution. The highly alkaline solution can be a liquid waste solution from a nuclear waste processing system. Methods can include combining the solution with a reductant capable of reducing technetium at the high pH of the solution and adding to or forming in the solution an adsorbent capable of adsorbing the precipitated technetium at the high pH of the solution.

  1. Column leaching test to evaluate the use of alkaline industrial wastes to neutralize acid mine tailings

    SciTech Connect

    Doye, I.; Duchesne, J.

    2005-08-01

    Acid mine drainage is a serious environmental problem caused by the oxidation of sulfide minerals that releases highly acidic, sulfate, and metals-rich drainage. In this study, alkaline industrial wastes were mixed with acid mine tailings in order to obtain neutral conditions. A series of column leaching tests were performed to evaluate the behavior of reactive mine tailings amended with alkaline-additions under dynamic conditions. Column tests were conducted of oxidized mine tailings combined with cement kiln dust, red mud bauxite, and mixtures of cement kiln dust with red mud bauxite. The pH results show the addition of 10% of alkaline materials permits the maintenance of near neutral conditions. In the presence of 10% alkaline material, the concentration of toxic metals such as Al, Cu, Fe, Zn are significantly reduced as well as the number of viable cells (Thiobacillus ferrooxidans) compared to control samples.

  2. cAMP/protein kinase A activates cystic fibrosis transmembrane conductance regulator for ATP release from rat skeletal muscle during low pH or contractions.

    PubMed

    Tu, Jie; Lu, Lin; Cai, Weisong; Ballard, Heather J

    2012-01-01

    We have shown that cystic fibrosis transmembrane conductance regulator (CFTR) is involved in ATP release from skeletal muscle at low pH. These experiments investigate the signal transduction mechanism linking pH depression to CFTR activation and ATP release, and evaluate whether CFTR is involved in ATP release from contracting muscle. Lactic acid treatment elevated interstitial ATP of buffer-perfused muscle and extracellular ATP of L6 myocytes: this ATP release was abolished by the non-specific CFTR inhibitor, glibenclamide, or the specific CFTR inhibitor, CFTR(inh)-172, suggesting that CFTR was involved, and by inhibition of lactic acid entry to cells, indicating that intracellular pH depression was required. Muscle contractions significantly elevated interstitial ATP, but CFTR(inh)-172 abolished the increase. The cAMP/PKA pathway was involved in the signal transduction pathway for CFTR-regulated ATP release from muscle: forskolin increased CFTR phosphorylation and stimulated ATP release from muscle or myocytes; lactic acid increased intracellular cAMP, pCREB and PKA activity, whereas IBMX enhanced ATP release from myocytes. Inhibition of PKA with KT5720 abolished lactic-acid- or contraction-induced ATP release from muscle. Inhibition of either the Na(+)/H(+)-exchanger (NHE) with amiloride or the Na(+)/Ca(2+)-exchanger (NCX) with SN6 or KB-R7943 abolished lactic-acid- or contraction-induced release of ATP from muscle, suggesting that these exchange proteins may be involved in the activation of CFTR. Our data suggest that CFTR-regulated release contributes to ATP release from contracting muscle in vivo, and that cAMP and PKA are involved in the activation of CFTR during muscle contractions or acidosis; NHE and NCX may be involved in the signal transduction pathway.

  3. Improvement of chemical monitoring of water-chemistry conditions at thermal power stations based on electric conductivity and pH measurements

    NASA Astrophysics Data System (ADS)

    Larin, A. B.; Larin, B. M.

    2016-05-01

    The increased requirements to the quality of the water heat conductor for working superhigh (SHP) and supercritical (SCP) pressure power plants and promising units, including combined-cycle gas turbine (CCGT) units and power plants with ultrasupercritical parameters (USCPs), can largely be satisfied through specific electric conductivity and pH measurements for cooled heat conductor samples combined with calculations of ionic equilibria and indirect measurements of several specified and diagnostic parameters. The possibility of calculating the ammonia and chloride concentrations and the total concentration of hardness and sodium cations in the feed water of drum-type boilers and the phosphate and salt contents in boiler water was demonstrated. An equation for evaluating the content of potentially acid substances in the feed water of monotube boilers was suggested. The potential of the developed procedure for evaluating the state of waterchemistry conditions (WCCs) in power plants with CCGT units was shown.

  4. [The arsenate Na3Fe2(AsO4) 3: structural study at low temperature and simulation of conduction properties of alkaline cations].

    PubMed

    Ouerfelli, Najoua; Guesmi, Abderrahmen; Mazza, Daniele; Zid, Mohamed Faouzi; Driss, Ahmed

    2008-05-01

    The crystal structure of the low-temperature garnet-like form of trisodium diiron(III) triarsenate, Na(3)Fe(2)(AsO(4))(3), exhibits a three-dimensional framework with small tunnels running along the [111] direction, in which the Na(+) cations are located. This study demonstrates the structural origins of the different ionic conductivities of the low- and high-temperature forms. Sodium conduction properties are simulated by means of the bond-valence-sum (BVS) model; the correlations between the low- and high-temperature crystal structures are discussed. The As, Fe and Na atoms lie on special positions (Wyckoff symbols 24d, 16a and 24c, respectively).

  5. Effect of the alkaline cation size on the conductivity in gel polymer electrolytes and their influence on photo electrochemical solar cells.

    PubMed

    Bandara, T M W J; Fernando, H D N S; Furlani, M; Albinsson, I; Dissanayake, M A K L; Ratnasekera, J L; Mellander, B-E

    2016-04-28

    The nature and concentration of cationic species in the electrolyte exert a profound influence on the efficiency of nanocrystalline dye-sensitized solar cells (DSSCs). A series of DSSCs based on gel electrolytes containing five alkali iodide salts (LiI, NaI, KI, RbI and CsI) and polyacrylonitrile with plasticizers were fabricated and studied, in order to investigate the dependence of solar cell performance on the cation size. The ionic conductivity of electrolytes with relatively large cations, K(+), Rb(+) and Cs(+), was higher and essentially constant, while for the electrolytes containing the two smaller cations, Na(+) and Li(+), the conductivity values were lower. The temperature dependence of conductivity in this series appears to follow the Vogel-Tamman-Fulcher equation. The sample containing the smallest cation shows the lowest conductivity and the highest activation energy of ∼36.5 meV, while K(+), Rb(+) and Cs(+) containing samples show an activation energy of ∼30.5 meV. DSSCs based on the gel electrolyte and a TiO2 double layer with the N719 dye exhibited an enhancement in the open circuit voltage with increasing cation size. This can be attributed to the decrease in the recombination rate of electrons and to the conduction band shift resulting from cation adsorption by TiO2. The maximum efficiency value, 3.48%, was obtained for the CsI containing cell. The efficiencies shown in this study are lower compared to values reported in the literature, and this can be attributed to the use of a single salt and the absence of other additives, since the focus of the present study was to analyze the cation effect. The highest short circuit current density of 9.43 mA cm(-2) was shown by the RbI containing cell. The enhancement of the solar cell performance with increasing size of the cation is discussed in terms of the effect of the cations on the TiO2 anode and ion transport in the electrolyte. In liquid electrolyte based DSSCs, the short circuit current density

  6. Synthesis and phase transitions of oxide-ion conducting compound La{sub 2}Mo{sub 2}O{sub 9} doped with alkaline metals

    SciTech Connect

    Kolesnikova, D. S.; Kharitonova, E. P.; Voronkova, V. I.

    2011-03-15

    The specific features of synthesis, polymorthism, and electric conductivity of oxide-ion conducting compounds La{sub 2-x}Me{sub x}Mo{sub 2}O{sub 9-y}, where Me = Na, K, Rb, or Cs, have been studied. Ceramic samples were obtained by solid-state synthesis in the temperature range of 960-1100 Degree-Sign C. The regions where solid solutions exist have been found to depend on the temperature of the sample firing. According to the calorimetric and electrophysical data, the phase transition from the monoclinic phase ({alpha}) to the cubic phase ({beta}) in samples doped with potassium and rubidium disappears at x = 0.02 and 0.04, respectively. In these cases the only transition from the cubic {beta}{sub ms} phase to the high-temperature cubic {beta} phase is observed near 450 Degree-Sign C. Doping with sodium and cesium does not suppress the {alpha} {yields} {beta} phase transition.

  7. Dynamics of pH modification of an acidic protein bait used for tropical fruit flies (Diptera: Tephritidae).

    PubMed

    Heath, Robert R; Vazquez, Aime; Schnell, Elena Q; Villareal, Janett; Kendra, Paul E; Epsky, Nancy D

    2009-12-01

    Several species of Anastrepha and Bactrocera fruit flies (Diptera: Tephritidae) are captured in traps baited with the protein bait NuLure combined with borax (sodium tetraborate decahydrate) in an aqueous solution, typically 9% NuLure (vol:vol) with 3% borax (wt:vol). NuLure is an acid hydrolysate of corn and has an acidic pH. Addition of borax makes the solution more alkaline, and increase in alkalinity results in increase of ammonia release from the bait solution. This is a very dynamic system, with resultant pH affected by factors such as the amount of borax added, the pH of the water used for preparation, the age of the bait solution, and the development of microbial growth. Problems with borax include amount needed to increase alkalinity of NuLure solutions, which creates difficulties in disposing of spent bait in fruit fly trapping programs. Therefore, research was conducted to evaluate NaOH as an alternative method to increase alkalinity of NuLure solutions. Laboratory experiments compared effect of NaOH versus borax for pH modification on changes in pH and ammonia content of NuLure solutions over time. Although NuLure/NaOH solutions could be adjusted to a more alkaline pH than NuLure/borax solutions, borax plays a critical role in pH stability over time. However, the pH of NuLure/NaOH is stabilized when propylene glycol (10% vol:vol) was used to prepare the bait solution. The use of NaOH can provide an alternative to the use of borax to increase bait solution alkalinity.

  8. Net alkalinity and net acidity 2: Practical considerations

    USGS Publications Warehouse

    Kirby, C.S.; Cravotta, C.A.

    2005-01-01

    The pH, alkalinity, and acidity of mine drainage and associated waters can be misinterpreted because of the chemical instability of samples and possible misunderstandings of standard analytical method results. Synthetic and field samples of mine drainage having various initial pH values and concentrations of dissolved metals and alkalinity were titrated by several methods, and the results were compared to alkalinity and acidity calculated based on dissolved solutes. The pH, alkalinity, and acidity were compared between fresh, unoxidized and aged, oxidized samples. Data for Pennsylvania coal mine drainage indicates that the pH of fresh samples was predominantly acidic (pH 2.5-4) or near neutral (pH 6-7); ??? 25% of the samples had pH values between 5 and 6. Following oxidation, no samples had pH values between 5 and 6. The Standard Method Alkalinity titration is constrained to yield values >0. Most calculated and measured alkalinities for samples with positive alkalinities were in close agreement. However, for low-pH samples, the calculated alkalinity can be negative due to negative contributions by dissolved metals that may oxidize and hydrolyze. The Standard Method hot peroxide treatment titration for acidity determination (Hot Acidity) accurately indicates the potential for pH to decrease to acidic values after complete degassing of CO2 and oxidation of Fe and Mn, and it indicates either the excess alkalinity or that required for neutralization of the sample. The Hot Acidity directly measures net acidity (= -net alkalinity). Samples that had near-neutral pH after oxidation had negative Hot Acidity; samples that had pH < 6.3 after oxidation had positive Hot Acidity. Samples with similar pH values before oxidation had dissimilar Hot Acidities due to variations in their alkalinities and dissolved Fe, Mn, and Al concentrations. Hot Acidity was approximately equal to net acidity calculated based on initial pH and dissolved concentrations of Fe, Mn, and Al minus the

  9. Crystal structure of alkaline cellulase K: insight into the alkaline adaptation of an industrial enzyme.

    PubMed

    Shirai, T; Ishida, H; Noda, J; Yamane, T; Ozaki, K; Hakamada, Y; Ito, S

    2001-07-27

    The crystal structure of the catalytic domain of alkaline cellulase K was determined at 1.9 A resolution. Because of the most alkaliphilic nature and it's highest activity at pH 9.5, it is used commercially in laundry detergents. An analysis of the structural bases of the alkaliphilic character of the enzyme suggested a mechanism similar to that previously proposed for alkaline proteases, that is, an increase in the number of Arg, His, and Gln residues, and a decrease in Asp and Lys residues. Some ion pairs were formed by the gained Arg residues, which is similar to what has been found in the alkaline proteases. Lys-Asp ion pairs are disfavored and partly replaced with Arg-Asp ion pairs. The alkaline adaptation appeared to be a remodeling of ion pairs so that the charge balance is kept in the high pH range.

  10. Archaeal Communities in a Heterogeneous Hypersaline-Alkaline Soil.

    PubMed

    Navarro-Noya, Yendi E; Valenzuela-Encinas, César; Sandoval-Yuriar, Alonso; Jiménez-Bueno, Norma G; Marsch, Rodolfo; Dendooven, Luc

    2015-01-01

    In this study the archaeal communities in extreme saline-alkaline soils of the former lake Texcoco, Mexico, with electrolytic conductivities (EC) ranging from 0.7 to 157.2 dS/m and pH from 8.5 to 10.5 were explored. Archaeal communities in the 0.7 dS/m pH 8.5 soil had the lowest alpha diversity values and were dominated by a limited number of phylotypes belonging to the mesophilic Candidatus Nitrososphaera. Diversity and species richness were higher in the soils with EC between 9.0 and 157.2 dS/m. The majority of OTUs detected in the hypersaline soil were members of the Halobacteriaceae family. Novel phylogenetic branches in the Halobacteriales class were detected in the soil, and more abundantly in soil with the higher pH (10.5), indicating that unknown and uncharacterized Archaea can be found in this soil. Thirteen different genera of the Halobacteriaceae family were identified and were distributed differently between the soils. Halobiforma, Halostagnicola, Haloterrigena, and Natronomonas were found in all soil samples. Methanogenic archaea were found only in soil with pH between 10.0 and 10.3. Retrieved methanogenic archaea belonged to the Methanosarcinales and Methanomicrobiales orders. The comparison of the archaeal community structures considering phylogenetic information (UniFrac distances) clearly clustered the communities by pH.

  11. Archaeal Communities in a Heterogeneous Hypersaline-Alkaline Soil

    PubMed Central

    Navarro-Noya, Yendi E.; Valenzuela-Encinas, César; Sandoval-Yuriar, Alonso; Jiménez-Bueno, Norma G.; Marsch, Rodolfo

    2015-01-01

    In this study the archaeal communities in extreme saline-alkaline soils of the former lake Texcoco, Mexico, with electrolytic conductivities (EC) ranging from 0.7 to 157.2 dS/m and pH from 8.5 to 10.5 were explored. Archaeal communities in the 0.7 dS/m pH 8.5 soil had the lowest alpha diversity values and were dominated by a limited number of phylotypes belonging to the mesophilic Candidatus Nitrososphaera. Diversity and species richness were higher in the soils with EC between 9.0 and 157.2 dS/m. The majority of OTUs detected in the hypersaline soil were members of the Halobacteriaceae family. Novel phylogenetic branches in the Halobacteriales class were detected in the soil, and more abundantly in soil with the higher pH (10.5), indicating that unknown and uncharacterized Archaea can be found in this soil. Thirteen different genera of the Halobacteriaceae family were identified and were distributed differently between the soils. Halobiforma, Halostagnicola, Haloterrigena, and Natronomonas were found in all soil samples. Methanogenic archaea were found only in soil with pH between 10.0 and 10.3. Retrieved methanogenic archaea belonged to the Methanosarcinales and Methanomicrobiales orders. The comparison of the archaeal community structures considering phylogenetic information (UniFrac distances) clearly clustered the communities by pH. PMID:26074731

  12. Growth of water hyacinth in municipal landfill leachate with different pH.

    PubMed

    El-Gendy, A S; Biswas, N; Bewtra, J K

    2004-07-01

    Batch experiments were conducted to investigate the effect of municipal landfill leachate pH on the growth of water hyacinth (Eichhornia crassipes). These experiments were carried out in a green house environment on leachate samples collected from Essex-Windsor Regional Landfill, Windsor, Ontario, Canada. It was found that water hyacinth plants survived in a pH range of 4.0 to 8.0. Both alkaline pH (above 8.0) and highly acidic pH (below 4.0) had inhibitory effect on the growth of plants. The pH range, for optimum growth of the water hyacinth plants was found to be 5.8 to 6.0. At optimum growth, water hyacinth had an average mean relative growth rate of 0.043 d-1. It was found that nitrogen compounds underwent different transformations depending on the pH of leachate. Plant uptake, nitrification and volatilization were among these transformations.

  13. Disposable all-solid-state pH and glucose sensors based on conductive polymer covered hierarchical AuZn oxide.

    PubMed

    Kim, Dong-Min; Cho, Seong Je; Cho, Chul-Ho; Kim, Kwang Bok; Kim, Min-Yeong; Shim, Yoon-Bo

    2016-05-15

    Poly(terthiophene benzoic acid) (pTBA) layered-AuZn alloy oxide (AuZnOx) deposited on the screen printed carbon electrode (pTBA/AuZnOx/SPCE) was prepared to create a disposable all-solid-state pH sensor at first. Further, FAD-glucose oxidase (GOx) was immobilized onto the pTBA/AuZnOx/SPCE to fabricate a glucose sensor. The characterizations of the sensor probe reveal that AuZnOx forms a homogeneous hierarchical structure, and that the polymerized pTBA layer on the alloy oxide surface captures GOx covalently. The benzoic acid group of pTBA coated on the probe layer synergetically improved the pH response of the alloy oxide and provide chemical binding sites to enzyme, which resulted in a Nernstian behavior (59.2 ± 0.5 mV/pH) in the pH range of 2-13. The experimental parameters affecting the glucose analysis were studied in terms of pH, temperature, humidity, and interferences. The sensor exhibited a fast response time <1s and a dynamic range between 30 and 500 mg/dL glucose with a detection limit of 17.23 ± 0.32 mg/dL. The reliabilities of the disposable pH and glucose sensors were examined for biological samples.

  14. Surfactant-enhanced alkaline flooding with weak alkalis

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1991-02-01

    The objective of Project BE4B in FY90 was to develop cost-effective and efficient chemical flooding formulations using surfactant-enhanced, lower pH (weak) alkaline chemical systems. Chemical systems were studied that mitigate the deleterious effects of divalent ions. The experiments were conducted with carbonate mixtures and carbonate/phosphate mixtures of pH 10.5, where most of the phosphate ions exist as the monohydrogen phosphate species. Orthophosphate did not further reduce the deleterious effect of divalent ions on interfacial tension behavior in carbonate solutions, where the deleterious effect of the divalent ions is already very low. When added to a carbonate mixture, orthophosphate did substantially reduce the adsorption of an atomic surfactant, which was an expected result; however, there was no correlation between the amount of reduction and the divalent ion levels. For acidic oils, a variety of surfactants are available commercially that have potential for use between pH 8.3 and pH 9.5. Several of these surfactants were tested with oil from Wilmington (CA) field and found to be suitable for use in that field. Two low-acid crude oils, with acid numbers of 0.01 and 0.27 mg KOH/g of oil, were studied. It was shown that surfactant-enhanced alkaline flooding does have merit for use with these low-acid crude oils. However, each low-acid oil tested was found to behave differently, and it was concluded that the applicability of the method must be experimentally determined for any given low-acid crude oil. 19 refs., 10 figs. 4 tabs.

  15. Catalytic Diversity in Alkaline Hydrothermal Vent Systems on Ocean Worlds

    NASA Astrophysics Data System (ADS)

    Cameron, Ryan D.; Barge, Laura; Chin, Keith B.; Doloboff, Ivria J.; Flores, Erika; Hammer, Arden C.; Sobron, Pablo; Russell, Michael J.; Kanik, Isik

    2016-10-01

    Hydrothermal systems formed by serpentinization can create moderate-temperature, alkaline systems and it is possible that this type of vent could exist on icy worlds such as Europa which have water-rock interfaces. It has been proposed that some prebiotic chemistry responsible for the emergence of life on Earth and possibly other wet and icy worlds could occur as a result ofredox potential and pH gradients in submarine alkaline hydrothermal vents (Russell et al., 2014). Hydrothermal chimneys formed in laboratory simulations of alkaline vents under early Earth conditions have precipitate membranes that contain minerals such as iron sulfides, which are hypothesized to catalyze reduction of CO2 (Yamaguchi et al. 2014, Roldan et al. 2014) leading to further organic synthesis. This CO2 reduction process may be affected by other trace components in the chimney, e.g. nickel or organic molecules. We have conducted experiments to investigate catalytic properties of iron and iron-nickel sulfides containing organic dopants in slightly acidic ocean simulants relevant to early Earth or possibly ocean worlds. We find that the electrochemical properties of the chimney as well as the morphology/chemistry of the precipitate are affected by the concentration and type of organics present. These results imply that synthesis of organics in water-rock systems on ocean worlds may lead to hydrothermal precipitates which can incorporate these organic into the mineral matrix and may affect the role of gradients in alkaline vent systems.Therefore, further understanding on the electroactive roles of various organic species within hydrothermal chimneys will have important implications for habitability as well as prebiotic chemistry. This work is funded by NASA Astrobiology Institute JPL Icy Worlds Team and a NAI Director's Discretionary Fund award.Yamaguchi A. et al. (2014) Electrochimica Acta, 141, 311-318.Russell, M. J. et al. (2014), Astrobiology, 14, 308-43.Roldan, A. (2014) Chem. Comm. 51

  16. [Modeling research on impact of pH on metals leaching behavior of air pollution control residues from MSW incinerator].

    PubMed

    Zhang, Hua; He, Pin-Jing; Li, Xin-Jie; Shao, Li-Ming

    2008-01-01

    Metals leaching behavior of air pollution control residues (APC residues) from municipal solid waste incinerator (MSWI) is greatly dependent on the leachate pH. pH-varying leaching tests and Visual MINTEQ modeling were conducted to investigate the mechanism of pH effect on the metals leaching characteristics from MSWI APC residues. Results show that, under acidic environment (for Cd, Zn, and Ni, pH < 8; for Pb, Cu, and Cr, pH < 6; for Al, pH < 4), leaching concentrations of metals increase greatly with the decrease of pH. Release of amphoteric metals, Pb and Zn, can be induced in strong alkaline leachate, reaching to 42 and 2.4 mg x L(-1) at pH 12.5 respectively. The equilibrium modeling results are well in agreement with the analyzed leaching concentrations. Variation of leachate pH changes the metals speciation in the leaching system, thus influencing their leaching concentrations. Speciation and leaching behavior of Pb, Zn, Cu, Ca, and Al mainly depend on their dissolution/precipitation reactions under different leachate pH. Leachability of Cd, Cr, and Ni can be lowered under acidic and neutral leachate pH due to HFO adsorption, while under alkaline conditions, the effect of adsorption is not significant and dissolution/precipitation becomes the major reactions controlling the leaching toxicity of these heavy metals.

  17. Anodes for alkaline electrolysis

    DOEpatents

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  18. The secondary alkaline zinc electrode

    NASA Astrophysics Data System (ADS)

    McLarnon, Frank R.; Cairns, Elton J.

    1991-02-01

    The worldwide studies conducted between 1975 and 1990 with the aim of improving cell lifetimes of secondary alkaline zinc electrodes are overviewed. Attention is given the design features and characteristics of various secondary alkaline zinc cells, including four types of zinc/nickel oxide cell designs (vented static-electrolyte, sealed static-electrolyte, vibrating-electrode, and flowing-electrolyte); two types of zinc/air cells (mechanically rechargeable consolidated-electrode and mechanically rechargeable particulate-electrode); zinc/silver oxide battery; zinc/manganese dioxide cell; and zinc/ferric cyanide battery. Particular consideration is given to recent research in the fields of cell thermodynamics, zinc electrodeposition, zinc electrodissolution, zinc corrosion, electrolyte properties, mathematical and phenomenological models, osmotic pumping, nonuniform current distribution, and cell cycle-life perforamnce.

  19. De Novo Transcriptional Analysis of Alfalfa in Response to Saline-Alkaline Stress

    PubMed Central

    An, Yi-Min; Song, Li-Li; Liu, Ying-Rui; Shu, Yong-Jun; Guo, Chang-Hong

    2016-01-01

    Saline-alkaline stress, caused by high levels of harmful carbonate salts and high soil pH, is a major abiotic stress that affects crop productivity. Alfalfa is a widely cultivated perennial forage legume with some tolerance to biotic and abiotic stresses, especially to saline-alkaline stress. To elucidate the mechanism underlying plant saline-alkaline tolerance, we conducted transcriptome analysis of whole alfalfa seedlings treated with saline-alkaline solutions for 0 day (control), 1 day (short-term treatment), and 7 days (long-term treatment) using ion torrent sequencing technology. A transcriptome database dataset of 53,853 unigenes was generated, and 2,286 and 2,233 genes were differentially expressed in the short-term and long-term treatment, respectively. Gene ontology analysis revealed 14 highly enriched pathways and demonstrated the differential response of metabolic pathways between the short-term and long-term treatment. The expression levels of 109 and 96 transcription factors were significantly altered significantly after 1 day and 7 days of treatment, respectively. Specific responses of peroxidase, flavonoids, and the light pathway component indicated that the antioxidant capacity was one of the central mechanisms of saline-alkaline stress tolerance response in alfalfa. Among the 18 differentially expressed genes examined by real time PCR, the expression levels of eight genes, including inositol transporter, DNA binding protein, raffinose synthase, ferritin, aldo/keto reductase, glutathione S-transferase, xyloglucan endotrans glucosylase, and a NAC transcription factor, exhibited different patterns in response to saline and alkaline stress. The expression levels of the NAC transcription factor and glutathione S-transferase were altered significantly under saline stress and saline-alkaline stress; they were upregulated under saline-alkaline stress and downregulated under salt stress. Physiology assays showed an increased concentration of reactive oxygen

  20. Toxicity of alkalinity to Hyalella azteca

    USGS Publications Warehouse

    Lasier, P.J.; Winger, P.V.; Reinert, R.E.

    1997-01-01

    Toxicity testing and chemical analyses of sediment pore water have been suggested for use in sediment quality assessments and sediment toxicity identification evaluations. However, caution should be exercised in interpreting pore-water chemistry and toxicity due to inherent chemical characteristics and confounding relationships. High concentrations of alkalinity, which are typical of sediment pore waters from many regions, have been shown to be toxic to test animals. A series of tests were conducted to assess the significance of elevated alkalinity concentrations to Hyalella azteca, an amphipod commonly used for sediment and pore-water toxicity testing. Toxicity tests with 14-d old and 7-d old animals were conducted in serial dilutions of sodium bicarbonate (NaHCO3) solutions producing alkalinities ranging between 250 to 2000 mg/L as CaCO3. A sodium chloride (NaCl) toxicity test was also conducted to verify that toxicity was due to bicarbonate and not sodium. Alkalinity was toxic at concentrations frequently encountered in sediment pore water. There was also a significant difference in the toxicity of alkalinity between 14-d old and 7-d old animals. The average 96-h LC50 for alkalinity was 1212 mg/L (as CaCO3) for 14-d old animals and 662 mg/L for the younger animals. Sodium was not toxic at levels present in the NaHCO3 toxicity tests. Alkalinity should be routinely measured in pore-water toxicity tests, and interpretation of toxicity should consider alkalinity concentration and test-organism tolerance.

  1. Quality-assurance results for field pH and specific-conductance measurements, and for laboratory analysis, National Atmospheric Deposition Program and National Trends Network; January 1980-September 1984

    USGS Publications Warehouse

    Schroder, L.J.; Brooks, M.H.; Malo, B.A.; Willoughby, T.C.

    1986-01-01

    Five intersite comparison studies for the field determination of pH and specific conductance, using simulated-precipitation samples, were conducted by the U.S.G.S. for the National Atmospheric Deposition Program and National Trends Network. These comparisons were performed to estimate the precision of pH and specific conductance determinations made by sampling-site operators. Simulated-precipitation samples were prepared from nitric acid and deionized water. The estimated standard deviation for site-operator determination of pH was 0.25 for pH values ranging from 3.79 to 4.64; the estimated standard deviation for specific conductance was 4.6 microsiemens/cm at 25 C for specific-conductance values ranging from 10.4 to 59.0 microsiemens/cm at 25 C. Performance-audit samples with known analyte concentrations were prepared by the U.S.G.S.and distributed to the National Atmospheric Deposition Program 's Central Analytical Laboratory. The differences between the National Atmospheric Deposition Program and national Trends Network-reported analyte concentrations and known analyte concentrations were calculated, and the bias and precision were determined. For 1983, concentrations of calcium, magnesium, sodium, and chloride were biased at the 99% confidence limit; concentrations of potassium and sulfate were unbiased at the 99% confidence limit. Four analytical laboratories routinely analyzing precipitation were evaluated in their analysis of identical natural- and simulated precipitation samples. Analyte bias for each laboratory was examined using analysis of variance coupled with Duncan 's multiple-range test on data produced by these laboratories, from the analysis of identical simulated-precipitation samples. Analyte precision for each laboratory has been estimated by calculating a pooled variance for each analyte. Interlaboratory comparability results may be used to normalize natural-precipitation chemistry data obtained from two or more of these laboratories. (Author

  2. Process for treating alkaline wastes for vitrification

    DOEpatents

    Hsu, Chia-lin W.

    1995-01-01

    A process for treating alkaline wastes for vitrification. The process involves acidifying the wastes with an oxidizing agent such as nitric acid, then adding formic acid as a reducing agent, and then mixing with glass formers to produce a melter feed. The nitric acid contributes nitrates that act as an oxidant to balance the redox of the melter feed, prevent reduction of certain species to produce conducting metals, and lower the pH of the wastes to a suitable level for melter operation. The formic acid reduces mercury compounds to elemental mercury for removal by steam stripping, and MnO.sub.2 to the Mn(II) ion to prevent foaming of the glass melt. The optimum amounts of nitric acid and formic acid are determined in relation to the composition of the wastes, including the concentrations of mercury (II) and MnO.sub.2, noble metal compounds, nitrates, formates and so forth. The process minimizes the amount of hydrogen generated during treatment, while producing a redox-balanced feed for effective melter operation and a quality glass product.

  3. Process for treating alkaline wastes for vitrification

    DOEpatents

    Hsu, C.L.W.

    1995-07-25

    A process is described for treating alkaline wastes for vitrification. The process involves acidifying the wastes with an oxidizing agent such as nitric acid, then adding formic acid as a reducing agent, and then mixing with glass formers to produce a melter feed. The nitric acid contributes nitrates that act as an oxidant to balance the redox of the melter feed, prevent reduction of certain species to produce conducting metals, and lower the pH of the wastes to a suitable level for melter operation. The formic acid reduces mercury compounds to elemental mercury for removal by steam stripping, and MnO{sub 2} to the Mn(II) ion to prevent foaming of the glass melt. The optimum amounts of nitric acid and formic acid are determined in relation to the composition of the wastes, including the concentrations of mercury (II) and MnO{sub 2}, noble metal compounds, nitrates, formates and so forth. The process minimizes the amount of hydrogen generated during treatment, while producing a redox-balanced feed for effective melter operation and a quality glass product. 4 figs.

  4. Alkaline battery operational methodology

    DOEpatents

    Sholklapper, Tal; Gallaway, Joshua; Steingart, Daniel; Ingale, Nilesh; Nyce, Michael

    2016-08-16

    Methods of using specific operational charge and discharge parameters to extend the life of alkaline batteries are disclosed. The methods can be used with any commercial primary or secondary alkaline battery, as well as with newer alkaline battery designs, including batteries with flowing electrolyte. The methods include cycling batteries within a narrow operating voltage window, with minimum and maximum cut-off voltages that are set based on battery characteristics and environmental conditions. The narrow voltage window decreases available capacity but allows the batteries to be cycled for hundreds or thousands of times.

  5. Alkaline Ammonia Electrolysis on Electrodeposited Platinum for Controllable Hydrogen Production.

    PubMed

    Gwak, Jieun; Choun, Myounghoon; Lee, Jaeyoung

    2016-02-19

    Ammonia is beginning to attract a great deal of attention as an alternative energy source carrier, because clean hydrogen can be produced through electrolytic processes without the emission of COx . In this study, we deposited various shapes of Pt catalysts under potentiostatic mode; the electrocatalytic oxidation behavior of ammonia using these catalysts was studied in alkaline media. The electrodeposited Pt was characterized by both qualitative and quantitative analysis. To discover the optimal structure and the effect of ammonia concentration, the bulk pH value, reaction temperature, and applied current of ammonia oxidation were investigated using potential sweep and galvanostatic methods. Finally, ammonia electrolysis was conducted using a zero-gap cell, producing highly pure hydrogen with an energy efficiency over 80 %.

  6. Alkaline fuel cell performance investigation

    NASA Technical Reports Server (NTRS)

    Martin, R. E.; Manzo, M. A.

    1988-01-01

    An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more that two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

  7. Surfactant-enhanced alkaline flooding for light oil recovery. [Annual report], 1993--1994

    SciTech Connect

    Wasan, D.T.

    1995-03-01

    In this report, we present the results of our experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, we have (1) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (2) investigated the kinetics of oil removal from a silica surface, and (3) developed a theoretical interfacial activity model for determining equilibrium interfacial tension. The results of the studies conducted during the course of this project are presented.

  8. Net alkalinity and net acidity 1: Theoretical considerations

    USGS Publications Warehouse

    Kirby, C.S.; Cravotta, C.A.

    2005-01-01

    Net acidity and net alkalinity are widely used, poorly defined, and commonly misunderstood parameters for the characterization of mine drainage. The authors explain theoretical expressions of 3 types of alkalinity (caustic, phenolphthalein, and total) and acidity (mineral, CO2, and total). Except for rarely-invoked negative alkalinity, theoretically defined total alkalinity is closely analogous to measured alkalinity and presents few practical interpretation problems. Theoretically defined "CO 2-acidity" is closely related to most standard titration methods with an endpoint pH of 8.3 used for determining acidity in mine drainage, but it is unfortunately named because CO2 is intentionally driven off during titration of mine-drainage samples. Using the proton condition/mass- action approach and employing graphs to illustrate speciation with changes in pH, the authors explore the concept of principal components and how to assign acidity contributions to aqueous species commonly present in mine drainage. Acidity is defined in mine drainage based on aqueous speciation at the sample pH and on the capacity of these species to undergo hydrolysis to pH 8.3. Application of this definition shows that the computed acidity in mg L -1 as CaCO3 (based on pH and analytical concentrations of dissolved FeII, FeIII, Mn, and Al in mg L -1):aciditycalculated=50{1000(10-pH)+[2(FeII)+3(FeIII)]/56+2(Mn)/ 55+3(Al)/27}underestimates contributions from HSO4- and H+, but overestimates the acidity due to Fe3+ and Al3+. However, these errors tend to approximately cancel each other. It is demonstrated that "net alkalinity" is a valid mathematical construction based on theoretical definitions of alkalinity and acidity. Further, it is shown that, for most mine-drainage solutions, a useful net alkalinity value can be derived from: (1) alkalinity and acidity values based on aqueous speciation, (2) measured alkalinity minus calculated acidity, or (3) taking the negative of the value obtained in a

  9. A Field-Based Aquatic Life Benchmark for Conductivity in ...

    EPA Pesticide Factsheets

    EPA announced the availability of the final report, A Field-Based Aquatic Life Benchmark for Conductivity in Central Appalachian Streams. This report describes a method to characterize the relationship between the extirpation (the effective extinction) of invertebrate genera and salinity (measured as conductivity) and from that relationship derives a freshwater aquatic life benchmark. This benchmark of 300 µS/cm may be applied to waters in Appalachian streams that are dominated by calcium and magnesium salts of sulfate and bicarbonate at circum-neutral to mildly alkaline pH. This report provides scientific evidence for a conductivity benchmark in a specific region rather than for the entire United States.

  10. Bacterial treatment of alkaline cement kiln dust using Bacillus halodurans strain KG1

    PubMed Central

    Kunal; Rajor, Anita; Siddique, Rafat

    2016-01-01

    This study was conducted to isolate an acid-producing, alkaliphilic bacterium to reduce the alkalinity of cement industry waste (cement kiln dust). Gram-positive isolate KG1 grew well at pH values of 6–12, temperatures of 28–50 °C, and NaCl concentrations of 0–16% and thus was further screened for its potential to reduce the pH of an alkaline medium. Phenotypic characteristics of the KG1 isolate were consistent with those of the genus Bacillus, and the highest level of 16S rRNA gene sequence similarity was found with Bacillus halodurans strain DSM 497 (94.7%). On the basis of its phenotypic characteristics and genotypic distinctiveness from other phylogenetic neighbors belonging to alkaliphilic Bacillus species, the isolated strain was designated B. halodurans strain KG1, with GenBank accession number JQ307184 (= NCIM 5439). Isolate KG1 reduced the alkalinity (by 83.64%) and the chloride content (by 86.96%) of cement kiln dust and showed a potential to be used in the cement industry for a variety of applications. PMID:26887220

  11. Bacterial treatment of alkaline cement kiln dust using Bacillus halodurans strain KG1.

    PubMed

    Kunal; Rajor, Anita; Siddique, Rafat

    2016-01-01

    This study was conducted to isolate an acid-producing, alkaliphilic bacterium to reduce the alkalinity of cement industry waste (cement kiln dust). Gram-positive isolate KG1 grew well at pH values of 6-12, temperatures of 28-50°C, and NaCl concentrations of 0-16% and thus was further screened for its potential to reduce the pH of an alkaline medium. Phenotypic characteristics of the KG1 isolate were consistent with those of the genus Bacillus, and the highest level of 16S rRNA gene sequence similarity was found with Bacillus halodurans strain DSM 497 (94.7%). On the basis of its phenotypic characteristics and genotypic distinctiveness from other phylogenetic neighbors belonging to alkaliphilic Bacillus species, the isolated strain was designated B. halodurans strain KG1, with GenBank accession number JQ307184 (= NCIM 5439). Isolate KG1 reduced the alkalinity (by 83.64%) and the chloride content (by 86.96%) of cement kiln dust and showed a potential to be used in the cement industry for a variety of applications.

  12. Eukaryotic diversity at pH extremes

    PubMed Central

    Amaral-Zettler, Linda A.

    2013-01-01

    Extremely acidic (pH < 3) and extremely alkaline (pH > 9) environments support a diversity of single-cell and to a lesser extent, multicellular eukaryotic life. This study compared alpha and beta diversity in eukaryotic communities from seven diverse aquatic environments with pH values ranging from 2 to 11 using massively-parallel pyrotag sequencing targeting the V9 hypervariable region of the 18S ribosomal RNA (rRNA) gene. A total of 946 operational taxonomic units (OTUs) were recovered at a 6% cut-off level (94% similarity) across the sampled environments. Hierarchical clustering of the samples segregated the communities into acidic and alkaline groups. Similarity percentage (SIMPER) analysis followed by indicator OTU analysis (IOA) and non-metric multidimensional scaling (NMDS) were used to determine which characteristic groups of eukaryotic taxa typify acidic or alkaline extremes and the extent to which pH explains eukaryotic community structure in these environments. Spain's Rio Tinto yielded the fewest observed OTUs while Nebraska Sandhills alkaline lakes yielded the most. Distinct OTUs, including metazoan OTUs, numerically dominated pH extreme sites. Indicator OTUs included the diatom Pinnularia and unidentified opisthokonts (Fungi and Filasterea) in the extremely acidic environments, and the ciliate Frontonia across the extremely alkaline sites. Inferred from NMDS, pH explained only a modest fraction of the variation across the datasets, indicating that other factors influence the underlying community structure in these environments. The findings from this study suggest that the ability for eukaryotes to adapt to pH extremes over a broad range of values may be rare, but further study of taxa that can broadly adapt across diverse acidic and alkaline environments, respectively present good models for understanding adaptation and should be targeted for future investigations. PMID:23335919

  13. Salt- and alkaline-tolerance are linked in Acacia.

    PubMed

    Bui, Elisabeth N; Thornhill, Andrew; Miller, Joseph T

    2014-07-01

    Saline or alkaline soils present a strong stress on plants that together may be even more deleterious than alone. Australia's soils are old and contain large, sometimes overlapping, areas of high salt and alkalinity. Acacia and other Australian plant lineages have evolved in this stressful soil environment and present an opportunity to understand the evolution of salt and alkalinity tolerance. We investigate this evolution by predicting the average soil salinity and pH for 503 Acacia species and mapping the response onto a maximum-likelihood phylogeny. We find that salinity and alkalinity tolerance have evolved repeatedly and often together over 25 Ma of the Acacia radiation in Australia. Geographically restricted species are often tolerant of extreme conditions. Distantly related species are sympatric in the most extreme soil environments, suggesting lack of niche saturation. There is strong evidence that many Acacia have distributions affected by salinity and alkalinity and that preference is lineage specific.

  14. Salt- and alkaline-tolerance are linked in Acacia

    PubMed Central

    Bui, Elisabeth N.; Thornhill, Andrew; Miller, Joseph T.

    2014-01-01

    Saline or alkaline soils present a strong stress on plants that together may be even more deleterious than alone. Australia's soils are old and contain large, sometimes overlapping, areas of high salt and alkalinity. Acacia and other Australian plant lineages have evolved in this stressful soil environment and present an opportunity to understand the evolution of salt and alkalinity tolerance. We investigate this evolution by predicting the average soil salinity and pH for 503 Acacia species and mapping the response onto a maximum-likelihood phylogeny. We find that salinity and alkalinity tolerance have evolved repeatedly and often together over 25 Ma of the Acacia radiation in Australia. Geographically restricted species are often tolerant of extreme conditions. Distantly related species are sympatric in the most extreme soil environments, suggesting lack of niche saturation. There is strong evidence that many Acacia have distributions affected by salinity and alkalinity and that preference is lineage specific. PMID:25079493

  15. Bacterial colonization of a fumigated alkaline saline soil.

    PubMed

    Bello-López, Juan M; Domínguez-Mendoza, Cristina A; de León-Lorenzana, Arit S; Delgado-Balbuena, Laura; Navarro-Noya, Yendi E; Gómez-Acata, Selene; Rodríguez-Valentín, Analine; Ruíz-Valdiviezo, Victor M; Luna-Guido, Marco; Verhulst, Nele; Govaerts, Bram; Dendooven, Luc

    2014-07-01

    After chloroform fumigating an arable soil, the relative abundance of phylotypes belonging to only two phyla (Actinobacteria and Firmicutes) and two orders [Actinomycetales and Bacillales (mostly Bacillus)] increased in a subsequent aerobic incubation, while it decreased for a wide range of bacterial groups. It remained to be seen if similar bacterial groups were affected when an extreme alkaline saline soil was fumigated. Soil with electrolytic conductivity between 139 and 157 dS m(-1), and pH 10.0 and 10.3 was fumigated and the bacterial community structure determined after 0, 1, 5 and 10 days by analysis of the 16S rRNA gene, while an unfumigated soil served as control. The relative abundance of the Firmicutes increased in the fumigated soil (52.8%) compared to the unfumigated soil (34.2%), while that of the Bacteroidetes decreased from 16.2% in the unfumigated soil to 8.8% in the fumigated soil. Fumigation increased the relative abundance of the genus Bacillus from 14.7% in the unfumigated soil to 25.7%. It was found that phylotypes belonging to the Firmicutes, mostly of the genus Bacillus, were dominant in colonizing the fumigated alkaline saline as found in the arable soil, while the relative abundance of a wide range of bacterial groups decreased.

  16. An overview on fermentation, downstream processing and properties of microbial alkaline proteases.

    PubMed

    Gupta, R; Beg, Q K; Khan, S; Chauhan, B

    2002-12-01

    Microbial alkaline proteases dominate the worldwide enzyme market, accounting for a two-thirds share of the detergent industry. Although protease production is an inherent property of all organisms, only those microbes that produce a substantial amount of extracellular protease have been exploited commercially. Of these, strains of Bacillus sp. dominate the industrial sector. To develop an efficient enzyme-based process for the industry, prior knowledge of various fermentation parameters, purification strategies and properties of the biocatalyst is of utmost importance. Besides these, the method of measurement of proteolytic potential, the selection of the substrate and the assay protocol depends upon the ultimate industrial application. A large array of assay protocols are available in the literature; however, with the predominance of molecular approaches for the generation of better biocatalysts, the search for newer substrates and assay protocols that can be conducted at micro/nano-scale are becoming important. Fermentation of proteases is regulated by varying the C/N ratio and can be scaled-up using fed-batch, continuous or chemostat approaches by prolonging the stationary phase of the culture. The conventional purification strategy employed, involving e.g., concentration, chromatographic steps, or aqueous two-phase systems, depends on the properties of the protease in question. Alkaline proteases useful for detergent applications are mostly active in the pH range 8-12 and at temperatures between 50 and 70 degrees C, with a few exceptions of extreme pH optima up to pH 13 and activity at temperatures up to 80-90 degrees C. Alkaline proteases mostly have their isoelectric points near to their pH optimum in the range of 8-11. Several industrially important proteases have been subjected to crystallization to extensively study their molecular homology and three-dimensional structures.

  17. Human radiation studies: Remembering the early years: Oral history of cell biologist Don Francis Petersen, Ph.D., conducted November 29, 1994

    SciTech Connect

    1995-08-01

    This report is a transcript of an interview of Dr. Don Francis Petersen by representatives of the US DOE Office of Human Radiation Experiments. Dr. Petersen was selected for this interview because of his long research career at Los Alamos and his knowledge of the Atomic Energy Commission`s biomedical program. Dr. Petersen did not personally conduct research on human subjects. After a brief biographical sketch Dr. Petersen discusses his remembrances of the early use of radionuclides as biological tracers, aspects of nuclear weapons testing in the 1940`s and 1950`s including fallout studies, the means by which research projects were approved, use of humans in the whole-body counter, and the Health Division Biomedical responsibilities.

  18. Alkaline electrochemical cells and method of making

    NASA Technical Reports Server (NTRS)

    Hoyt, H. E.; Pfluger, H. L. (Inventor)

    1970-01-01

    Equilibrated cellulose ether membranes of increased electrolytic conductivity for use as separators in concentrated alkaline electrochemical cells are investigated. The method of making such membranes by equilibration to the degree desired in an aqueous alkali solution mantained at a temperature below about 10 C is described.

  19. Electrical Switchability and Dry-Wash Durability of Conductive Textiles

    NASA Astrophysics Data System (ADS)

    Wu, Bangting; Zhang, Bowu; Wu, Jingxia; Wang, Ziqiang; Ma, Hongjuan; Yu, Ming; Li, Linfan; Li, Jingye

    2015-06-01

    There is growing interest in the area of conductive textiles in the scientific and industrial community. Herein, we successfully prepared a conductive textile via covalently grafting polyaniline (PANI) onto cotton by a multi-step treatment process. The conductivity of the resultant fabric could be tuned by immersing in water having different pH values. The conductive and insulating properties of the textile could be conveniently switched by alternately immersing in acidic and alkaline bath solutions. Most importantly, the resultant conductive fabrics were able to withstand 40 simulated dry-wash cycles, with almost no decay in the electrical conductivity, indicating their excellent dry-wash durability. The present strategy for fabricating conductive fabrics with excellent switchability of electrical properties and dry-wash durability is expected to provide inspiration for the production of multifunctional conductive textiles for use in hash or sensitive conditions.

  20. Electrical Switchability and Dry-Wash Durability of Conductive Textiles

    PubMed Central

    Wu, Bangting; Zhang, Bowu; Wu, Jingxia; Wang, Ziqiang; Ma, Hongjuan; Yu, Ming; Li, Linfan; Li, Jingye

    2015-01-01

    There is growing interest in the area of conductive textiles in the scientific and industrial community. Herein, we successfully prepared a conductive textile via covalently grafting polyaniline (PANI) onto cotton by a multi-step treatment process. The conductivity of the resultant fabric could be tuned by immersing in water having different pH values. The conductive and insulating properties of the textile could be conveniently switched by alternately immersing in acidic and alkaline bath solutions. Most importantly, the resultant conductive fabrics were able to withstand 40 simulated dry-wash cycles, with almost no decay in the electrical conductivity, indicating their excellent dry-wash durability. The present strategy for fabricating conductive fabrics with excellent switchability of electrical properties and dry-wash durability is expected to provide inspiration for the production of multifunctional conductive textiles for use in hash or sensitive conditions. PMID:26066704

  1. Kinetic Release of Alkalinity from Particle-Containing Oil-in-Water Emulsions

    NASA Astrophysics Data System (ADS)

    Muller, K.; Chapra, S. C.; Ramsburg, A.

    2014-12-01

    Oil-in-water emulsions are typically employed during remediation to promote biotic reduction of contaminants. Emulsions, however, hold promise for encapsulated delivery of many types of active ingredients required for successful site remediation or long-term site stewardship. Our research is currently focused on using alkalinity-containing particles held within oil-in-water emulsions to sustain control of subsurface pH. Here we describe results from laboratory experiments and mathematical modeling conducted to quantify the kinetics associated with the emulsion delivery and alkalinity release process. Kinetically stable oil-in-water emulsions containing (~60 nmCaCO3 or ~100 nm MgO particles) were previously developed using soybean oil and Gum Arabic as a stabilizing agent. Batch and column experiments were employed to assess the accessibility and release of the alkalinity from the emulsion. Successive additions of HCl were used in batch systems to produce several pH responses (pH rebounds) that were subsequently modeled to elucidate release mechanisms and rates for varying emulsion compositions and particle types. Initial results suggest that a linear-driving-force model is generally able to capture the release behavior in the batch system when the temporally-constant, lumped mass-transfer coefficient is scaled by the fraction of particle mass remaining within the droplets. This result suggests that the rate limiting step in the release process may be the interphase transfer of reactive species at the oil-water interface. 1-d column experiments were also completed in order to quantify the extent and rate of alkalinity release from emulsion droplets retained in a sandy medium. Alkalinity release from the retained droplets treated a pH 4 influent water for 25-60 pore volumes (the duration depended on particle type and mass loading), and the cessation in treatment corresponded to exhaustion of the particle mass held within the oil. Column experiments were simulated

  2. A finite element model of conduction, convection, and phase change near a solid/melt interface. Ph.D. Thesis - Michigan Univ.

    NASA Technical Reports Server (NTRS)

    Viterna, Larry A.

    1991-01-01

    Detailed understanding of heat transfer and fluid flow is required for many aerospace thermal systems. These systems often include phase change and operate over a range of accelerations or effective gravitational fields. An approach to analyzing such systems is presented which requires the simultaneous solution of the conservation laws of energy, momentum, and mass, as well as an equation of state. The variable property form of the governing equations are developed in two-dimensional Cartesian coordinates for a Newtonian fluid. A numerical procedure for solving the governing equations is presented and implemented in a computer program. The Galerkin form of the finite element method is used to solve the spatial variation of the field variables, along with the implicit Crank-Nicolson time marching algorithm. Quadratic Langrangian elements are used for the internal energy and the two components of velocity. Linear Lagrangian elements are used for the pressure. The location of the solid/liquid interface as well as the temperatures are determined form the calculated internal energy and pressure. This approach is quite general in that it can describe heat transfer without phase change, phase change with a sharp interface, and phase change without an interface. Analytical results from this model are compared to those of other researchers studying transient conduction, convection, and phase change and are found to be in good agreement. The numerical procedure presented requires significant computer resources, but this is not unusual when compared to similar studies by other researchers. Several methods are suggested to reduce the computational times.

  3. Alkaline Capacitors Based on Nitride Nanoparticles

    NASA Technical Reports Server (NTRS)

    Aldissi, Matt

    2003-01-01

    High-energy-density alkaline electrochemical capacitors based on electrodes made of transition-metal nitride nanoparticles are undergoing development. Transition- metal nitrides (in particular, Fe3N and TiN) offer a desirable combination of high electrical conductivity and electrochemical stability in aqueous alkaline electrolytes like KOH. The high energy densities of these capacitors are attributable mainly to their high capacitance densities, which, in turn, are attributable mainly to the large specific surface areas of the electrode nanoparticles. Capacitors of this type could be useful as energy-storage components in such diverse equipment as digital communication systems, implanted medical devices, computers, portable consumer electronic devices, and electric vehicles.

  4. Miniaturization of cytotoxicity tests for concentration range-finding studies prior to conducting the pH 6.7 Syrian hamster embryo cell-transformation assay.

    PubMed

    Plöttner, Sabine; Käfferlein, Heiko U; Brüning, Thomas

    2013-08-15

    The Syrian hamster embryo (SHE) cell-transformation assay (SHE assay) is a promising alternative method to animal testing for the identification of potential carcinogens in vitro. Prior to conducting the SHE assay the appropriate concentration range for each test chemical must be established, with a maximum concentration causing approximately 50% cytotoxicity. Concentration range-finding is done in separate experiments, which are similar to the final SHE assay but with less replicates and more concentrations. Here we present an alternative for the cytotoxicity testing by miniaturization of the test procedure by use of 24-well plates and surpluses from feeder-cell preparations as target cells. In addition, we integrated the photometry-based neutral red (NR) assay. For validation of the assay, incubations with dimethyl sulf-oxide, p-phenylenediamine-2HCl, aniline, o-toluidine-HCl, 2,4-diaminotoluene, and 2-naphthylamine were carried out in the miniaturized approach and compared with the standard procedure in terms of calculating the relative plating efficiencies (RPEs). To directly compare both methods, concentrations that produced 50% cytotoxicity (IC50) were calculated. Excellent associations were observed between the number of colonies and NR uptake. For all test substances a concentration-dependent, concomitant decrease of NR uptake in the miniaturized approach and RPEs in the standard test was observed after a 7-day incubation. The results from both test setups showed a comparable order of magnitude and the IC50 values differed by a factor <2 (1.4-1.9), depending on the substance in question. Overall, the miniaturized approach should be considered an improved alternative for cytotoxicity testing in the SHE assay, as it saves valuable SHE cells and speeds-up the time, to obtain test results more rapidly.

  5. Alkaline solution absorption of carbon dioxide method and apparatus

    DOEpatents

    Hobbs, D.T.

    1991-01-01

    Disclosed is a method for measuring the concentration of hydroxides (or pH) in alkaline solutions, using the tendency of hydroxides to adsorb CO{sub 2}. The method comprises passing CO{sub 2} over the surface of an alkaline solution in a remote tank before and after measurements of the CO{sub 2} concentration. Comparison of the measurements yields the adsorption fraction from which the hydroxide concentration can be calculated using a correlation of hydroxide or pH to adsorption fraction. A schematic is given of a process system according to a preferred embodiment of the invention. 2 figs.

  6. ALKALINITY, PH, AND COPPER CORROSION BY-PRODUCT RELEASE

    EPA Science Inventory

    Contrary to expectations, higher bicarbonate concentrations exacerbate copper corrosion rates and by-product release. In fact, as illustrated by monitoring experiences of large utilities and by laboratory data, the concentration of copper corrosion by-products in drinking water i...

  7. Precipitation strengthened high strength, high conductivity Cu-Cr-Nb alloys produced by chill block melt spinning. Final Report Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Ellis, David L.; Michal, Gary M.

    1989-01-01

    A series of Cu-based alloys containing 2 to 10 a/o Cr and 1 to 5 a/o Nb were produced by chill block melt spinning (CBMS). The melt spun ribbons were consolidated and hot rolled to sheet to produce a supersaturated Cu-Cr-Nb solid solution from which the high melting point intermetallic compound Cr2Nb could be precipitated to strengthen the Cu matrix. The results show that the materials possess electrical conductivities in excess of 90 percent that of pure Cu at 200 C and above. The strengths of the Cu-Cr-Nb alloys were much greater than Cu, Cu-0.6 Cr, NARloy-A, and NARloy-Z in the as-melt spun condition. The strengths of the consolidated materials were less than Cu-Cr and Cu-Cr-Zr below 500 C and 600 C respectively, but were significantly better above these temperatures. The strengths of the consolidated materials were greater than NARloy-Z, at all temperatures. The GLIDCOP possessed similar strength levels up to 750 C when the strength of the Cu-Cr-Nb alloys begins to degrade. The long term stability of the Cu-Cr-Nb alloys was measured by the microhardness of aged samples and the growth of precipitates. The microhardness measurements indicate that the alloys overage rapidly, but do not suffer much loss in strength between 10 and 100 hours which confirms the results of the electrical resistivity measurements taken during the aging of the alloys at 500 C. The loss in strength from peak strength levels is significant, but the strength remains exceptionally good. Transmission electron microscopy (TEM) of the as-melt spun samples revealed that Cr2Nb precipitates formed in the liquid Cu during the chill block melt spinning, indicating a very strong driving force for the formation of the precipitates. The TEM of the aged and consolidated materials indicates that the precipitates coarsen considerably, but remain in the submicron range.

  8. Alkaline quinone flow battery.

    PubMed

    Lin, Kaixiang; Chen, Qing; Gerhardt, Michael R; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro W; Hardee, David; Gordon, Roy G; Aziz, Michael J; Marshak, Michael P

    2015-09-25

    Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy.

  9. Advanced alkaline water electrolysis

    NASA Astrophysics Data System (ADS)

    Wakabayashi, N.; Torikai, E.; Kawami, Y.; Takenaka, H.

    Results are presented of experimental studies of possible separators and electrodes for use in advanced, high-temperature, high-pressure alkaline water electrolyzers. Material evaluations in alkaline water electrolyzers at temperatures from 100 to 120 C have shown a new type polytetrafluoroethylene membrane impregnated with potassium titanate to be the most promising when the separator is prepared by the hydrothermal treatment of a porous PFTE membrane impregnated with hydrated titanium oxide. Measurements of cell voltages in 30% KOH at current densities from 5 to 100 A/sq dm at temperatures up to 120 C with nickel electrodes of various structures have shown the foamed nickel electrode, with an average pore size of 1-1.5 mm, to have the best performance. When the foamed nickel is coated by fine powdered nickel, carbonyl nickel or Raney nickel to increase electrode surface areas, even lower cell voltages were found, indicating better performance.

  10. Chloride-inducible transient apoplastic alkalinizations induce stomata closure by controlling abscisic acid distribution between leaf apoplast and guard cells in salt-stressed Vicia faba.

    PubMed

    Geilfus, Christoph-Martin; Mithöfer, Axel; Ludwig-Müller, Jutta; Zörb, Christian; Muehling, Karl H

    2015-11-01

    Chloride stress causes the leaf apoplast transiently to alkalize, an event that is presumed to contribute to the ability of plants to adapt to saline conditions. However, the initiation of coordinated processes downstream of the alkalinization is unknown. We hypothesize that chloride-inducible pH dynamics are a key chemical feature modulating the compartmental distribution of abscisic acid (ABA) and, as a consequence, affecting stomata aperture. Apoplastic pH and stomata aperture dynamics in intact Vicia faba leaves were monitored by microscopy-based ratio imaging and porometric measurements of stomatal conductance. ABA concentrations in leaf apoplast and guard cells were compared with pH dynamics by gas-chromatography-mass-spectrometry (GC-MS) and liquid-chromatography-tandem-mass spectrometry (LC-MS/MS). Results demonstrate that, upon chloride addition to roots, an alkalizing factor that initiates the pH dynamic propagates from root to leaf in a way similar to xylem-distributed water. In leaves, it induces a systemic transient apoplastic alkalinization that causes apoplastic ABA concentration to increase, followed by an elevation of endogenous guard cell ABA. We conclude that the transient alkalinization, which is a remote effect of chloride stress, modulates the compartmental distribution of ABA between the leaf apoplast and the guard cells and, in this way, is instrumental in inducing stomata closure during the beginning of salinity.

  11. Influence of pH of spray solution on optoelectronic properties of cadmium oxide thin films

    NASA Astrophysics Data System (ADS)

    Hodlur, R. M.; Rabinal, M. K.

    2015-03-01

    Highly conducting transparent cadmium oxide thin films were prepared by the conventional spray pyrolysis technique. The pH of the spray solution is varied by adding ammonia/hydrochloric acid. The effect of pH on the morphology, crystallinity and optoelectronic properties of these films is studied. The structural analysis showed all the films in the cubic phase. For the films with pH < 7 (acidic condition), the preferred orientation is along the (111) direction and for those with pH >7 (alkaline condition), the preferred orientation is along the (200) direction. A lowest resistivity of 9.9 × 10-4 Ω·cm (with carrier concentration = 5.1 × 1020 cm-3, mobility = 12.4 cm2/(V·s)) is observed for pH ≈ 12. The resistivity is tuned almost by three orders of magnitude by controlling the bath pH with optical transmittance more than 70%. Thus, the electrical conductivity of CdO films could be easily tuned by simply varying the pH of the spray solution without compromising the optical transparency.

  12. Acid transformation of bauxite residue: Conversion of its alkaline characteristics.

    PubMed

    Kong, Xiangfeng; Li, Meng; Xue, Shengguo; Hartley, William; Chen, Chengrong; Wu, Chuan; Li, Xiaofei; Li, Yiwei

    2017-02-15

    Bauxite residue (BR) is a highly alkaline solid hazardous waste produced from bauxite processing for alumina production. Alkaline transformation appears to reduce the environmental risk of bauxite residue disposal areas (BRDAs) whilst potentially providing opportunities for the sustainable reuse and on-going management of BR. Mineral acids, a novel citric acid and a hybrid combination of acid-gypsum treatments were investigated for their potential to reduce residue pH and total alkalinity and transform the alkaline mineral phase. XRD results revealed that with the exception of andradite, the primary alkaline solid phases of cancrinite, grossular and calcite were transformed into discriminative products based on the transformation used. Supernatants separated from BR and transformed bauxite residue (TBR) displayed distinct changes in soluble Na, Ca and Al, and a reduction in pH and total alkalinity. SEM images suggest that mineral acid transformations promote macro-aggregate formation, and the positive promotion of citric acid, confirming the removal or reduction in soluble and exchangeable Na. NEXAFS analysis of Na K-edge revealed that the chemical speciation of Na in TBRs was consistent with BR. Three acid treatments and gypsum combination had no effect on Na speciation, which affects the distribution of Na revealed by sodium STXM imaging.

  13. Nitrogen isotope evidence for alkaline lakes on late Archean continents

    NASA Astrophysics Data System (ADS)

    Stüeken, E. E.; Buick, R.; Schauer, A. J.

    2015-02-01

    Nitrogen isotope ratios in ancient sedimentary rocks are generally interpreted as a proxy for metabolic nitrogen pathways and the redox state of the water column. Fractionation processes occurring under anoxic, alkaline conditions during the dissociation of NH4+ to H+ and volatile NH3 are frequently overlooked, although this mechanism imparts large isotopic fractionations. Here we propose that NH3 volatilization is largely responsible for δ15N values of up to + 50 ‰ at high C/N ratios in the late Archean Tumbiana Formation. This sequence of sedimentary rocks represents a system of lakes that formed on subaerial flood basalts and were partly filled by basaltic volcanic ash. Aqueous alteration of volcanic glass followed by evaporative concentration of ions should have led to the development of high alkalinity with a pH of 9 or higher, as in modern analogues. In this sedimentologically unusual setting, nitrogen isotope ratios thus provide indirect evidence for the oldest alkaline lake system in the rock record. These very heavy lacustrine δ15N values contrast markedly with those of Archean marine sedimentary rocks, making a Precambrian "soda ocean" unlikely. Today, alkaline lakes are among the most productive ecosystems on Earth. Some nutrients, in particular molybdenum, are more soluble at high pH, and certain prebiotic reactions would likely have been favored under alkaline conditions in similar settings earlier in Earth's history. Hence alkaline lakes in the Archean could have been significant for the origin and early evolution of life.

  14. Characteristics of plasmalemma alkaline phosphatase of rat mesenteric artery.

    PubMed

    Kwan, C Y

    1983-01-01

    General characteristics of alkaline phosphatase activity of the plasma membrane-enriched fraction isolated from rat mesenteric arteries were investigated. The vascular smooth muscle plasmalemma alkaline phosphatase is a metalloenzyme which is strongly inhibited by chelating agents and this inhibition can be completely overcome by addition of Mg2+ or Ca2+. Zn2+ only partially reactivates the enzyme in the presence of low concentrations of EDTA. The enzymatic hydrolysis of p-nitrophenyl phosphate, beta-glycerophosphate, alpha-glycerophosphate, or 3'-adenosine monophosphate showed an optimal activity in the alkaline region between pH 9 and 11. The alkaline phosphatase activity is distinctly different from the plasmalemma ATPase and 5'-nucleotidase activities with respect to their pH dependence, influence by added divalent metal ions and stability against heat inactivation. Vanadate ion, being structurally similar to the transition state analog of the phosphoryl group, potently inhibits alkaline phosphatase with an apparent Ki of 1.5 microM. The altered alkaline phosphatase activity of vascular smooth muscle in relation to its possible physiological function and pathophysiological manifestation associated with hypertensive disease are discussed.

  15. [Effects of simulated acid rain on respiration rate of cropland system with different soil pH].

    PubMed

    Zhu, Xue-zhu; Zhang, Gao-chuan; Li, Hui

    2009-10-15

    To evaluate the effects of acid rain on the respiration rate of cropland system, an outdoor pot experiment was conducted with paddy soils of pH 5.48 (S1), pH 6.70 (S1) and pH 8.18 (S3) during the 2005-2007 wheat-growing seasons. The cropland system was exposed to acid rain by spraying the wheat foliage and irrigating the soil with simulated rainwater of T1 (pH 6.0), T2 (pH 6.0, ionic concentration was twice as rainwater T1), and T3 (pH 4.4, ionic concentration was twice as rainwater T1), respectively. The static opaque chamber-gas chromatograph method was used to measure CO2 fluxes from cropland system. The results showed that acid rain affected the respiration rate of cropland system through crop plant, and the cropland system could adapt to acid rain. Acid rainwater significantly increased the average respiration rate in alkaline soil (S3) cropland system, while it had no significant effects on the average respiration rate in neutral soil (S2) and acidic soil (S1) cropland systems. During 2005-2006, after the alkaline soil cropland system was treated with rainwater T3, the average respiration rate was 23.6% and 27.6% higher than that of alkaline soil cropland system treated with rainwater T1 and T2, respectively. During March to April, the respiration rate was enhanced with the increase of rainwater ionic concentration, while it was dropped with the decrease of rainwater pH value in acidic soil cropland system. It was demonstrated that soil pH and crop plant played important roles on the respiration rate of cropland system.

  16. Nitrification Enhancement through pH Control with Rotating Biological Contactors

    DTIC Science & Technology

    1981-09-01

    Inst. of Sew. Purif., 130 (1964). 31. Engel, M. S. and M. Alexander, " Growth and Autotrophic Metabolism of Nitrosomonas Europaea ," Jour. Bact., 76, 217...relative effectiveness of four different alkaline chemicals on enhancing the nitrifying process under optimum pH conditions was evaluated in Phase II...111 6.12 Relative RBC Heterotrophic Bacteria Growth Under pH Conditions from pH 7.0 to pH 8.5 ....... ............. .. 112 6.13 Batch Alkalinity

  17. Predicting species’ tolerance to salinity and alkalinity using distribution data and geochemical modelling: a case study using Australian grasses

    PubMed Central

    Saslis-Lagoudakis, C. Haris; Hua, Xia; Bui, Elisabeth; Moray, Camile; Bromham, Lindell

    2015-01-01

    Background and Aims Salt tolerance has evolved many times independently in different plant groups. One possible explanation for this pattern is that it builds upon a general suite of stress-tolerance traits. If this is the case, then we might expect a correlation between salt tolerance and other tolerances to different environmental stresses. This association has been hypothesized for salt and alkalinity tolerance. However, a major limitation in investigating large-scale patterns of these tolerances is that lists of known tolerant species are incomplete. This study explores whether species’ salt and alkalinity tolerance can be predicted using geochemical modelling for Australian grasses. The correlation between taxa found in conditions of high predicted salinity and alkalinity is then assessed. Methods Extensive occurrence data for Australian grasses is used together with geochemical modelling to predict values of pH and electrical conductivity to which species are exposed in their natural distributions. Using parametric and phylogeny-corrected tests, the geochemical predictions are evaluated using a list of known halophytes as a control, and it is determined whether taxa that occur in conditions of high predicted salinity are also found in conditions of high predicted alkalinity. Key Results It is shown that genera containing known halophytes have higher predicted salinity conditions than those not containing known halophytes. Additionally, taxa occurring in high predicted salinity tend to also occur in high predicted alkalinity. Conclusions Geochemical modelling using species’ occurrence data is a potentially useful approach to predict species’ relative natural tolerance to challenging environmental conditions. The findings also demonstrate a correlation between salinity tolerance and alkalinity tolerance. Further investigations can consider the phylogenetic distribution of specific traits involved in these ecophysiological strategies, ideally by

  18. Yield performance of cowpea genotypes grown in alkaline soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cowpea or Southernpea [Vigna unguiculata (L.) Walp.] is an important legume crop used as a feed for livestock, as a green vegetable and for consumption of its dry beans which provide 22-25% protein. The crop is very sensitive to alkaline soil conditions. When grown at soil pH of 7.5 or higher, cowp...

  19. Field screening of cowpea cultivars for alkaline soil tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cowpea or Southernpea [Vigna unguiculata (L.) Walp.] is an important legume crop used as a feed for livestock, as a green vegetable and for consumption of its dry beans which provide 22-25% protein. The crop is very sensitive to alkaline soil conditions. When grown at soil pH of 7.5 or higher, cowp...

  20. Development of a pH/alkalinity treatment model for applications of the lampricide TFM to streams tributary to the Great Lakes

    USGS Publications Warehouse

    Bills, Terry D.; Boogaard, Michael A.; Johnson, David A.; Brege, Dorance C.; Scholefield, Ronald J.; Westman, R. Wayne; Stephens, Brian E.

    2003-01-01

    It has long been known that the toxicity of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) is influenced by chemical and physical properties of water. As the pH, conductivity, and alkalinity of water increase, greater concentrations of TFM are required to kill sea lamprey (Petromyzon marinus) larvae. Consequently, the concentration of TFM required for effective treatment varies among streams. Brown trout (Salmo trutta) and sea lamprey larvae were exposed to a series of TFM concentrations in a continuous-flow diluter for 12 h. Twenty five exposures were conducted at various water alkalinities and pHs that treatment personnel encounter during lampricide treatments. Survival/mortality data were analyzed for lampricide concentrations that produced 50 and 99.9% mortality (LC50 and LC99.9) for sea lamprey larvae and 25 and 50% mortality (LC25 and LC50) for brown trout. Linear regression analyses were performed for each set of tests for each selected alkalinity by comparing the 12-h post exposure LC99.9 sea lamprey data and LC25 brown trout data at each pH. Mortality data from on-site toxicity tests conducted by lampricide control personnel were compared to predicted values from the pH/alkalinity prediction model. Of the 31 tests examined, 27 resulted in the LC100s (lowest TFM concentration where 100% mortality of sea lamprey was observed after 12 h of exposure) falling within 0.2 mg/L of the predicted sea lamprey minimum lethal (LC99.9) range. The pH/alkalinity prediction model provides managers with an operational tool that reduces the amount of TFM required for effective treatment while minimizing the impact on non-target organisms.

  1. Plant Habitat (PH)

    NASA Technical Reports Server (NTRS)

    Onate, Bryan

    2016-01-01

    The International Space Station (ISS) will soon have a platform for conducting fundamental research of Large Plants. Plant Habitat (PH) is designed to be a fully controllable environment for high-quality plant physiological research. PH will control light quality, level, and timing, temperature, CO2, relative humidity, and irrigation, while scrubbing ethylene. Additional capabilities include leaf temperature and root zone moisture and oxygen sensing. The light cap will have red (630 nm), blue (450 nm), green (525 nm), far red (730 nm) and broad spectrum white LEDs. There will be several internal cameras (visible and IR) to monitor and record plant growth and operations.

  2. TMC-1 Mediates Alkaline Sensation in C. elegans through Nociceptive Neurons.

    PubMed

    Wang, Xiang; Li, Guang; Liu, Jie; Liu, Jianfeng; Xu, X Z Shawn

    2016-07-06

    Noxious pH triggers pungent taste and nocifensive behavior. While the mechanisms underlying acidic pH sensation have been extensively characterized, little is known about how animals sense alkaline pH in the environment. TMC genes encode a family of evolutionarily conserved membrane proteins whose functions are largely unknown. Here, we characterize C. elegans TMC-1, which was suggested to form a Na(+)-sensitive channel mediating salt chemosensation. Interestingly, we find that TMC-1 is required for worms to avoid noxious alkaline environment. Alkaline pH evokes an inward current in nociceptive neurons, which is primarily mediated by TMC-1 and to a lesser extent by the TRP channel OSM-9. However, unlike OSM-9, which is sensitive to both acidic and alkaline pH, TMC-1 is only required for alkali-activated current, revealing a specificity for alkaline sensation. Ectopic expression of TMC-1 confers alkaline sensitivity to alkali-insensitive cells. Our results identify an unexpected role for TMCs in alkaline sensation and nociception.

  3. Neutralization of acid mine drainage using the final product from CO2 emissions capture with alkaline paper mill waste.

    PubMed

    Pérez-López, Rafael; Castillo, Julio; Quispe, Dino; Nieto, José Miguel

    2010-05-15

    In this study, experiments were conducted to investigate the applicability of low-cost alkaline paper mill wastes as acidity neutralizing agents for treatment of acid mine drainage (AMD). Paper wastes include a calcium mud by-product from kraft pulping, and a calcite powder from a previous study focused on sequestering CO(2) by carbonation of calcium mud. The neutralization process consisted of increase of pH by alkaline additive dissolution, decrease of metals solubility and precipitation of gypsum and poorly crystallized Fe-Al oxy-hydroxides/oxy-hydroxysulphates, which acted as a sink for trace elements to that extent that solutions reached the pre-potability requirements of water for human consumption. This improvement was supported by geochemical modelling of solutions using PHREEQC software, and observations by scanning electron microscope and X-ray diffraction of reaction products. According to PHREEQC simulations, the annual amount of alkaline additive is able to treat AMD (pH 3.63, sulphate 3800 mg L(-1), iron 348 mg L(-1)) with an average discharge of about 114 and 40 Ls(-1) for calcium mud and calcite powder, respectively. Likewise, given the high potential of calcium mud to sequester CO(2) and of resulting calcite powder to neutralize AMD, paper wastes could be a promising solution for facing this double environmental problem.

  4. [Alkaline phosphatase in Amoeba proteus].

    PubMed

    Sopina, V A

    2005-01-01

    In free-living Amoeba proteus (strain B), 3 phosphatase were found after disc-electrophoresis of 10 microg of protein in PAGE and using 1-naphthyl phosphate as a substrate a pH 9.0. These phosphatases differed in their electrophoretic mobilities - "slow" (1-3 bands), "middle" (one band) and "fast" (one band). In addition to 1-naphthyl phosphate, "slow" phosphatases were able to hydrolyse 2-naphthyl phosphate and p-nitrophenyl phosphate. They were slightly activated by Mg2+, completely inhibited by 3 chelators (EDTA, EGTA and 1,10-phenanthroline), L-cysteine, sodium dodecyl sulfate and Fe2+, Zn2+ and Mn2+ (50 mM), considerably inactivated by orthovanadate, molybdate, phosphatase inhibitor cocktail 1, p-nitrophenyl phosphate, Na2HPO4, DL-dithiothreitol and urea and partly inhibited by H2O2, DL-phenylalanine, 2-mercaptoethanol, phosphatase inhibitor cocktail 2 and Ca2+. Imidazole, L-(+)-tartrate, okadaic acid, NaF and sulfhydryl reagents -p-(hydroxy-mercuri)benzoate and N-ethylmaleimide - had no influence on the activity of "slow" phosphatases. "Middle" and "fast" phosphatases, in contrast to "slow" ones, were not inactivated by 3 chelators. The "middle" phosphatase differed from the "fast" one by smaller resistance to urea, Ca2+, Mn2+, phosphates and H2O2 and greater resistance to dithiothreitol and L-(+)-tartrate. In addition, the "fast" phosphatase was inhibited by L-cysteine but the "middle" one was activated by it. Of 5 tested ions (Mg2+, Cu2+, Mn2+, Ca2+ and Zn2+), only Zn2+ reactivated "slow" phosphatases after their inactivation by EDTA treatment. The reactivation of apoenzyme was only partial (about 35 %). Thus, among phosphatases found in amoebae at pH 9.0, only "slow" ones are Zn-metalloenzymes and may be considered as alkaline phosphatases (EC 3.1.3.1). It still remains uncertain, to which particular phosphatase class "middle" and "fast" phosphatases (pH 9.0) may belong.

  5. Alkaline phosphatase of Physarum polycephalum is insoluble.

    PubMed

    Furuhashi, Kiyoshi

    2008-02-01

    The plasmodia of Physarum polycephalum grow as multinucleated cells in the presence of sufficient humidity and nutriment. Under non-illuminating conditions, stresses such as low temperature or high concentrations of salts transform the plasmodia into spherules whereas dehydration induces sclerotization. Some phosphatases including protein phosphatase and acid phosphatase have been purified from the plasmodia, but alkaline phosphatase remains to be elucidated. Phosphatase of the plasmodia, spherules and sclerotia was visualized by electrophoresis gel-staining assay using 5-bromo-4-chloro-3-indolyl phosphate. Insoluble fractions of the sclerotia were abundant in phosphatase activity. The phosphatase which was extracted by nonionic detergent was subjected to column chromatography and preparative electrophoresis. Purified phosphatase showed the highest activity at pH 8.8, indicating that this enzyme belongs to alkaline phosphatase. The apparent molecular mass from sodium dodecyl sulfate-polyacrylamide gel electrophoresis under non-reducing condition was estimated to be 100 kDa whereas that under reducing was 105 kDa. An amount of 1% sodium dodecyl sulfate or 0.5 M NaCl had no effects on the activity although the phosphatase showed heat instability, Mg(2+)-dependency and sensitivity to 2-glycerophosphate or NaF. The extracting conditions and enzymatic properties suggest that this alkaline phosphatase which is in a membrane-bound form plays important roles in phosphate metabolism.

  6. Kinetics of the alkaline hydrolysis of nitrocellulose.

    PubMed

    Christodoulatos, C; Su, T L; Koutsospyros, A

    2001-01-01

    Cellulose nitrate (nitrocellulose) is an explosive solid substance used in large quantities in various formulations of rocket and gun propellants. Safe destruction of nitrocellulose can be achieved by alkaline hydrolysis, which converts it to biodegradable products that can then be treated by conventional biological processes. The kinetics of the alkaline hydrolysis of munitions-grade nitrocellulose in sodium hydroxide solutions were investigated in completely mixed batch reactors. Experiments were conducted using solutions of alkaline strength ranging from 0.1 to 15% by mass and temperatures in the range of 30 to 90 degrees C. Regression analysis of the kinetic data revealed that alkaline hydrolysis of nitrocellulose is of the order 1.0 and 1.5 with respect to nitrocellulose and hydroxide concentration, respectively. The activation energy of the hydrolysis reaction was found to be 100.9 kJ/mol with a preexponential Arrhenius constant of 4.73 x 10(13). Nitrite and nitrate, in a 3:1 ratio, were the primary nitrogen species present in the posthydrolysis solution. The kinetic information is pertinent to the development and optimization of nitrocellulose chemical-biological treatment systems.

  7. Important electromigration effects of carbon dioxide in capillary electrophoresis at high pH.

    PubMed

    Malá, Zdena; Gebauer, Petr; Boček, Petr

    2011-06-01

    This paper deals with unwanted effects of carbonate in capillary zone electrophoretic analyses of anions in alkaline BGEs with indirect UV absorption and conductivity detection. Computer simulations and experimental study of selected model systems have shown that carbon dioxide absorbed from air into BGEs and samples induce important electrophoretic effects like formation of new additional zones and/or boundaries that may further induce strong and pronounced temporary changes in the migration of analytes. Examples are reduction of the pH of alkaline BGEs around pH 11 by up to 1 unit or formation of a pronounced detectable carbon dioxide peak comparable with peaks of analytes at 1 mM level. The higher the pH of the BGE, the stronger these effects and the broader their spectrum, involving (i) changes of effective mobilities and selectivity due to changes in pH of the BGE, (ii) occurrence of additional system zones appearing in form of peaks, dips or more complex disturbances in the detection signal, (iii) temporary interactions with the sample components and subsequent modification of the separation process and of its result. This paper reveals all these effects and brings the knowledge necessary to prevent problems with qualitative and quantitative evaluation of the analysis results.

  8. The potential for constructed wetlands to treat alkaline bauxite-residue leachate: Phragmites australis growth.

    PubMed

    Higgins, D; Curtin, T; Pawlett, M; Courtney, R

    2016-12-01

    High alkalinity (pH > 12) of bauxite-residue leachates presents challenges for the long-term storage and managements of the residue. Recent evidence has highlighted the potential for constructed wetlands to effectively buffer the alkalinity, but there is limited evidence on the potential for wetland plants to establish and grow in soils inundated with residue leachate. A pot-based trial was conducted to investigate the potential for Phragmites australis to establish and grow in substrate treated with residue leachate over a pH range of 8.6-11.1. The trial ran for 3 months, after which plant growth and biomass were determined. Concentrations of soluble and exchangeable trace elements in the soil substrate and also in the aboveground and belowground biomass were determined. Residue leachate pH did not affect plant biomass or microbial biomass. With the exception of Na, there was no effect on exchangeable trace elements in the substrate; however, increases in soluble metals (As, Cd and Na) were observed with increasing leachate concentration. Furthermore, increases in Al, As and V were observed in belowground biomass and for Cd and Cr in aboveground biomass. Concentrations within the vegetation biomass were less than critical phytotoxic levels. Results demonstrate the ability for P. australis to grow in bauxite-residue leachate-inundated growth media without adverse effects.

  9. Alkaline flocculation of Phaeodactylum tricornutum induced by brucite and calcite

    DOE PAGES

    Vandamme, Dries; Pohl, Philip I.; Beuckels, Annelies; ...

    2015-08-20

    Alkaline flocculation holds great potential as a low-cost harvesting method for marine microalgae biomass production. Alkaline flocculation is induced by an increase in pH and is related to precipitation of calcium and magnesium salts. In this study, we used the diatom Phaeodactylum tricornutum as model organism to study alkaline flocculation of marine microalgae cultured in seawater medium. Flocculation started when pH was increased to 10 and flocculation efficiency reached 90% when pH was 10.5, which was consistent with precipitation modeling for brucite or Mg(OH)2. Compared to freshwater species, more magnesium is needed to achieve flocculation (>7.5 mM). Zeta potential measurementsmore » suggest that brucite precipitation caused flocculation by charge neutralization. When calcium concentration was 12.5 mM, flocculation was also observed at a pH of 10. Furthermore, zeta potential remained negative up to pH 11.5, suggesting that precipitated calcite caused flocculation by a sweeping coagulation mechanism.« less

  10. The potential for constructed wetlands to treat alkaline bauxite residue leachate: laboratory investigations.

    PubMed

    R, Buckley; T, Curtin; R, Courtney

    2016-07-01

    High alkalinity (pH > 12) of bauxite residue leachates presents challenges for the long-term storage and managements of the residue. Whilst the use of constructed wetlands is gaining in interest for its use in the treatment of alkaline waters, thus far, there is limited evidence of its suitability for treating NaOH dominated bauxite residue leachate. A series of batch trials were conducted to investigate the potential for constructed wetland conferred mechanisms (dilution water quality, contact with CO2, and substrate type) for treating NaOH solutions to levels permissible for discharge (p < 9). Results demonstrate that significant reductions in solution pH can be achieved depending on the diluting water quality. Levels achieved may not always be suitable for direct discharge (i.e. pH ≤ 9), but further reductions occur with carbonation and soil contact. The extent of pH decrease and the timeframe required are influenced by soil quality, with greater efficiency observed in soils with higher organic matter content. Decrease in solution pH to discharge permit values are possible through a combination of the mechanisms occurring in a constructed wetland. Formation of a calcite precipitate was observed in some treatments and further characterisation by XRD and XPS suggested surface coating with Na2CO3. It is therefore suggested that, under suitable conditions, constructed wetland technology can reduce leachate pH to <9 through mechanisms supporting the precipitation of sodium carbonate from solution. Further trials should investigate the activity under biological conditions representative of an operating constructed wetland.

  11. Response of Desulfovibrio vulgaris to alkaline stress.

    PubMed

    Stolyar, Sergey; He, Qiang; Joachimiak, Marcin P; He, Zhili; Yang, Zamin Koo; Borglin, Sharon E; Joyner, Dominique C; Huang, Katherine; Alm, Eric; Hazen, Terry C; Zhou, Jizhong; Wall, Judy D; Arkin, Adam P; Stahl, David A

    2007-12-01

    The response of exponentially growing Desulfovibrio vulgaris Hildenborough to pH 10 stress was studied using oligonucleotide microarrays and a study set of mutants with genes suggested by microarray data to be involved in the alkaline stress response deleted. The data showed that the response of D. vulgaris to increased pH is generally similar to that of Escherichia coli but is apparently controlled by unique regulatory circuits since the alternative sigma factors (sigma S and sigma E) contributing to this stress response in E. coli appear to be absent in D. vulgaris. Genes previously reported to be up-regulated in E. coli were up-regulated in D. vulgaris; these genes included three ATPase genes and a tryptophan synthase gene. Transcription of chaperone and protease genes (encoding ATP-dependent Clp and La proteases and DnaK) was also elevated in D. vulgaris. As in E. coli, genes involved in flagellum synthesis were down-regulated. The transcriptional data also identified regulators, distinct from sigma S and sigma E, that are likely part of a D. vulgaris Hildenborough-specific stress response system. Characterization of a study set of mutants with genes implicated in alkaline stress response deleted confirmed that there was protective involvement of the sodium/proton antiporter NhaC-2, tryptophanase A, and two putative regulators/histidine kinases (DVU0331 and DVU2580).

  12. Autonomous in situ measurements of seawater alkalinity.

    PubMed

    Spaulding, Reggie S; DeGrandpre, Michael D; Beck, James C; Hart, Robert D; Peterson, Brittany; De Carlo, Eric H; Drupp, Patrick S; Hammar, Terry R

    2014-08-19

    Total alkalinity (AT) is an important parameter for describing the marine inorganic carbon system and understanding the effects of atmospheric CO2 on the oceans. Measurements of AT are limited, however, because of the laborious process of collecting and analyzing samples. In this work we evaluate the performance of an autonomous instrument for high temporal resolution measurements of seawater AT. The Submersible Autonomous Moored Instrument for alkalinity (SAMI-alk) uses a novel tracer monitored titration method where a colorimetric pH indicator quantifies both pH and relative volumes of sample and titrant, circumventing the need for gravimetric or volumetric measurements. The SAMI-alk performance was validated in the laboratory and in situ during two field studies. Overall in situ accuracy was -2.2 ± 13.1 μmol kg(-1) (n = 86), on the basis of comparison to discrete samples. Precision on duplicate analyses of a carbonate standard was ±4.7 μmol kg(-1) (n = 22). This prototype instrument can measure in situ AT hourly for one month, limited by consumption of reagent and standard solutions.

  13. Changes in methane oxidation activity and methanotrophic community composition in saline alkaline soils.

    PubMed

    Serrano-Silva, Nancy; Valenzuela-Encinas, César; Marsch, Rodolfo; Dendooven, Luc; Alcántara-Hernández, Rocio J

    2014-05-01

    The soil of the former Lake Texcoco is a saline alkaline environment where anthropogenic drainage in some areas has reduced salt content and pH. Potential methane (CH4) consumption rates were measured in three soils of the former Lake Texcoco with different electrolytic conductivity (EC) and pH, i.e. Tex-S1 a >18 years drained soil (EC 0.7 dS m(-1), pH 8.5), Tex-S2 drained for ~10 years (EC 9.0 dS m(-1), pH 10.3) and the undrained Tex-S3 (EC 84.8 dS m(-1), pH 10.3). An arable soil from Alcholoya (EC 0.7 dS m(-1), pH 6.7), located nearby Lake Texcoco was used as control. Methane oxidation in the soil Tex-S1 (lowest EC and pH) was similar to that in the arable soil from Alcholoya (32.5 and 34.7 mg CH4 kg(-1) dry soil day(-1), respectively). Meanwhile, in soils Tex-S2 and Tex-S3, the potential CH4 oxidation rates were only 15.0 and 12.8 mg CH4 kg(-1) dry soil day(-1), respectively. Differences in CH4 oxidation were also related to changes in the methane-oxidizing communities in these soils. Sequence analysis of pmoA gene showed that soils differed in the identity and number of methanotrophic phylotypes. The Alcholoya soil and Tex-S1 contained phylotypes grouped within the upland soil cluster gamma and the Jasper Ridge, California JR-2 clade. In soil Tex-S3, a phylotype related to Methylomicrobium alcaliphilum was detected.

  14. The alkalinizing effects of metabolizable bases in the healthy calf.

    PubMed Central

    Naylor, J M; Forsyth, G W

    1986-01-01

    The alkalinizing effect of citrate, acetate, propionate, gluconate, L and DL-lactate were compared in healthy neonatal calves. The calves were infused for a 3.5 hour period with 150 mmol/L solutions of the sodium salts of the various bases. Blood pH, base excess, and metabolite concentrations were measured and the responses compared with sodium bicarbonate and sodium chloride infusion. D-gluconate and D-lactate had poor alkalinizing abilities and accumulated in blood during infusion suggesting that they are poorly metabolized by the calf. Acetate, L-lactate and propionate had alkalinizing effects similar to bicarbonate, although those of acetate had a slightly better alkalinizing effect than L-lactate. Acetate was more effectively metabolized because blood acetate concentrations were lower than L-lactate concentrations. There was a tendency for a small improvement in metabolism of acetate and lactate with age. Sodium citrate infusion produced signs of hypocalcemia, presumably because it removed ionized calcium from the circulation. D-gluconate, D-lactate and citrate are unsuitable for use as alkalinizing agents in intravenous fluids. Propionate, acetate and L-lactate are all good alkalinizing agents in healthy calves but will not be as effective in situations where tissue metabolism is impaired. PMID:3024796

  15. Sphagnum establishment in alkaline fens: Importance of weather and water chemistry.

    PubMed

    Vicherová, Eliška; Hájek, Michal; Šmilauer, Petr; Hájek, Tomáš

    2017-02-15

    Sphagnum expansion to alkaline fens has accelerated during the last decades in Europe, leading to changes in diversity, habitat distributions and carbon storage. The causes are still not clearly understood and involve an interplay between climate change, hydrology, nutrient supply and Sphagnum physiology. We conducted a 4-year field experiment in eight fens in Central European highlands and assessed survival and establishment of individual apical shoot fragments of S. flexuosum, S. warnstorfii and S. squarrosum transplanted along the microtopographical gradient. In a laboratory experiment, we tested combined effects of desiccation and high calcium bicarbonate concentration on Sphagnum survival. We found that in unflooded positions, living shoots of Sphagnum and brown mosses lowered [Ca(2+)] and pH in their capillary water, in contrast to dead fragments; yet without differences between species. Survival and expansion of Sphagnum fragments, which did not die of acute calcium toxicity during first weeks/months, was negatively affected by dry weather and alkaline water chemistry, reflecting Sphagnum intolerance to desiccation and to combined high [Ca(2+)] and pH. Shoot fragments expanded to patches only when precipitation was high. Interestingly, non-toxic concentration of calcium bicarbonate reduced desiccation damage in Sphagnum, probably through protection of membranes or other cell components. This mechanism would facilitate Sphagnum survival in elevated, frequently desiccated microhabitats of calcareous fens such as brown-moss hummocks. However, since water-retaining capacity of few Sphagnum shoots is insufficient to change water chemistry in its surroundings, surface acidification may occur only once the environment (e.g. sufficient humidity) enabled expansion to larger mats. Then, the retained rainwater together with hardly decomposable Sphagnum litter would separate mire surface from groundwater, speeding up successional shift towards poor fens. Sphagnum

  16. Extracellular alkaline proteinase of Colletotrichum gloeosporioides.

    PubMed

    Dunaevsky, Ya E; Matveeva, A R; Beliakova, G A; Domash, V I; Belozersky, M A

    2007-03-01

    The main proteinase of the filamentous fungus Colletotrichum gloeosporioides causing anthracnoses and serious problems for production and storage of agricultural products has molecular mass of 57 kD and was purified more than 200-fold to homogeneity with the yield of 5%. Maximal activity of the proteinase is at pH 9.0-10.0, and the enzyme is stable at pH 6.0-11.5 (residual activity not less than 70%). The studied enzyme completely kept its activity to 55 degrees C, with a temperature optimum of 45 degrees C. The purified C. gloeosporioides proteinase is stable at alkaline pH values, but rapidly loses its activity at pH values lower than 5.0. Addition of bovine serum albumin stabilizes the enzyme under acidic conditions. Data on inhibitor analysis and substrate specificity of the enzyme allow its classification as a serine proteinase of subtilisin family. It is demonstrated that the extracellular proteinase of C. gloeosporioides specifically effects plant cell wall proteins. It is proposed that the studied proteinase--via hydrolysis of cell wall--provides for penetration of the fungus into the tissues of the host plant.

  17. Changes in the bacterial populations of the highly alkaline saline soil of the former lake Texcoco (Mexico) following flooding.

    PubMed

    Valenzuela-Encinas, César; Neria-González, Isabel; Alcántara-Hernández, Rocio J; Estrada-Alvarado, Isabel; Zavala-Díaz de la Serna, Francisco Javier; Dendooven, Luc; Marsch, Rodolfo

    2009-07-01

    Flooding an extreme alkaline-saline soil decreased alkalinity and salinity, which will change the bacterial populations. Bacterial 16S rDNA libraries were generated of three soils with different electrolytic conductivity (EC), i.e. soil with EC 1.7 dS m(-1) and pH 7.80 (LOW soil), with EC 56 dS m(-1) and pH 10.11 (MEDIUM soil) and with EC 159 dS m(-1) and pH 10.02 (HIGH soil), using universal bacterial oligonucleotide primers, and 463 clone 16S rDNA sequences were analyzed phylogenetically. Library proportions and clone identification of the phyla Proteobacteria, Actinobacteria, Acidobacteria, Cyanobacteria, Bacteroidetes, Firmicutes and Cloroflexi showed that the bacterial communities were different. Species and genera of the Rhizobiales, Rhodobacterales and Xanthomonadales orders of the alpha- and gamma-subdivision of Proteobacteria were found at the three sites. Species and genera of the Rhodospirillales, Sphingobacteriales, Clostridiales, Oscillatoriales and Caldilineales were found only in the HIGH soil, Sphingomonadales, Burkholderiales and Pseudomonadales in the MEDIUM soil, Myxococcales in the LOW soil, and Actinomycetales in the MEDIUM and LOW soils. It was found that the largest diversity at the order and species level was found in the MEDIUM soil as bacteria of both the HIGH and LOW soils were found in it.

  18. Simultaneous production of biopesticide and alkaline proteases by Bacillus thuringiensis using sewage sludge as a raw material.

    PubMed

    Tyagi, R D; Sikati Foko, V; Barnabe, S; Vidyarthi, A S; Valéro, J R; Surampalli, R Y

    2002-01-01

    The simultaneous production of Bacillus thuringiensis (Bt) based biopesticide and proteases was studied using synthetic medium and wastewater sludge as a raw material. The studies were conducted in shake flask and computer controlled 15-L capacity fermentors. Measuring viable cell and spore counts, entomotoxicity and protease activity monitored the progress of the biopesticide production process. A higher viable cell count and spore count was observed in synthetic Soya medium, however, higher entomotoxicity and protease activity were observed in wastewater sludge medium. Thus, the wastewater sludge is a better raw material than commercial Soya medium for the biopesticides and enzyme production. The maximum entomotoxicity and protease activity observed in the fermentor was 9,332 IU/microL and 4.58 IU/mL, respectively. The proteases produced by Bt were also characterised. Two types of proteases were detected; neutral proteases with pH optimum 7.0 and alkaline proteases with pH optimum 10-11. Further, two types of alkaline proteases were detected; one having a pH and temperature optimum at 10 and 50 degrees C while the other at 11 and 70 degrees C. The protease thermal stability was found to increase in the presence of CaCl2, indicating the proteases were metalloproteases.

  19. Alkaline battery, separator therefore

    NASA Technical Reports Server (NTRS)

    Schmidt, George F. (Inventor)

    1980-01-01

    An improved battery separator for alkaline battery cells has low resistance to electrolyte ion transfer and high resistance to electrode ion transfer. The separator is formed by applying an improved coating to an electrolyte absorber. The absorber, preferably, is a flexible, fibrous, and porous substrate that is resistant to strong alkali and oxidation. The coating composition includes an admixture of a polymeric binder, a hydrolyzable polymeric ester and inert fillers. The coating composition is substantially free of reactive fillers and plasticizers commonly employed as porosity promoting agents in separator coatings. When the separator is immersed in electrolyte, the polymeric ester of the film coating reacts with the electrolyte forming a salt and an alcohol. The alcohol goes into solution with the electrolyte while the salt imbibes electrolyte into the coating composition. When the salt is formed, it expands the polymeric chains of the binder to provide a film coating substantially permeable to electrolyte ion transfer but relatively impermeable to electrode ion transfer during use.

  20. Alkaline Comet Assay for Assessing DNA Damage in Individual Cells.

    PubMed

    Pu, Xinzhu; Wang, Zemin; Klaunig, James E

    2015-08-06

    Single-cell gel electrophoresis, commonly called a comet assay, is a simple and sensitive method for assessing DNA damage at the single-cell level. It is an important technique in genetic toxicological studies. The comet assay performed under alkaline conditions (pH >13) is considered the optimal version for identifying agents with genotoxic activity. The alkaline comet assay is capable of detecting DNA double-strand breaks, single-strand breaks, alkali-labile sites, DNA-DNA/DNA-protein cross-linking, and incomplete excision repair sites. The inclusion of digestion of lesion-specific DNA repair enzymes in the procedure allows the detection of various DNA base alterations, such as oxidative base damage. This unit describes alkaline comet assay procedures for assessing DNA strand breaks and oxidative base alterations. These methods can be applied in a variety of cells from in vitro and in vivo experiments, as well as human studies.

  1. Long-term alkalinity decrease and acidification of estuaries in northwestern Gulf of Mexico.

    PubMed

    Hu, Xinping; Pollack, Jennifer Beseres; McCutcheon, Melissa R; Montagna, Paul A; Ouyang, Zhangxian

    2015-03-17

    More than four decades of alkalinity and pH data (late 1960s to 2010) from coastal bays along the northwestern Gulf of Mexico were analyzed for temporal changes across a climatic gradient of decreasing rainfall and freshwater inflow, from northeast to southwest. The majority (16 out of 27) of these bays (including coastal waters) showed a long-term reduction in alkalinity at a rate of 3.0-21.6 μM yr(-1). Twenty-two bays exhibited pH decreases at a rate of 0.0014-0.0180 yr(-1). In contrast, a northernmost coastal bay exhibited increases in both alkalinity and pH. Overall, the two rates showed a significant positive correlation, indicating that most of these bays, especially those at lower latitudes, have been experiencing long-term acidification. The observed alkalinity decrease may be caused by reduced riverine alkalinity export, a result of precipitation decline under drought conditions, and freshwater diversion for human consumption, as well as calcification in these bays. A decrease in alkalinity inventory and accompanying acidification may have negative impacts on shellfish production in these waters. In addition, subsequent reduction in alkalinity export from these bays to the adjacent coastal ocean may also decrease the buffer capacity of the latter against future acidification.

  2. Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments.

    PubMed

    Kitadai, Norio

    2015-12-01

    Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

  3. Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments

    NASA Astrophysics Data System (ADS)

    Kitadai, Norio

    2015-12-01

    Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

  4. Amelioration of an Ultisol profile acidity using crop straws combined with alkaline slag.

    PubMed

    Li, Jiu-yu; Masud, M M; Li, Zhong-yi; Xu, Ren-kou

    2015-07-01

    The acidity of Ultisols (pH <5) is detrimental to crop production. Technologies should be explored to promote base saturation and liming effect for amelioration of Ultisol pH. Column leaching experiments were conducted to investigate the amelioration effects of canola straw (CS) and peanut straw (PS) in single treatment and in combination whether with alkaline slag (AS) or with lime on Ultisol profile acidity. The treatment without liming materials was set as control, and the AS and lime in single treatment are set for comparison. Results indicated that all the liming materials increase soil profile pH and soil exchangeable base cations at the 0-40-cm depth, except that the lime had amelioration effect just on 0 to 15-cm profile. The amelioration effect of the liming materials on surface soil acidity was mainly dependent on the ash alkalinity in organic materials or acid neutralization capacity of inorganic materials. Specific adsorption of sulfate (SO4(2-)) or organic anions, decarboxylation of organic acids/anions, and the association of H(+) with organic anions induced a "liming effect" of crop residues and AS on subsoil acidity. Moreover, SO4(2-) and chloride (Cl(-)) in PS, CS, and AS primarily induced base cations to move downward to subsoil and exchange with exchangeable aluminum (Al(3+)) and protons (H(+)). These anions also promoted the exchangeable Al to leach out of the soil profile. The CS was more effective than PS in decreasing soil acidity in the subsoil, which mainly resulted from higher sulfur (S) and Cl content in CS compared to PS. The CS combined with AS was the better amendment choice in practical agricultural systems.

  5. Managing land application of coal seam water: A field study of land amendment irrigation using saline-sodic and alkaline water on a Red Vertisol.

    PubMed

    Bennett, J McL; Marchuk, A; Raine, S R; Dalzell, S A; Macfarlane, D C

    2016-12-15

    Coal seam (CS) gas operations coproduce water with gas from confined CS aquifers. This CS water represents a potential agricultural resource if the water is able to be chemically amended to comply with management guidelines. Stoichiometric quantities of sulphur and gypsum amendments can be used to neutralise the alkalinity and reduce the sodicity of CS water respectively. These amendments can either be mixed in-line at a water treatment plant or applied directly to land prior to the application of CS water (a practice termed land amendment irrigation - LAI). This study compared the efficacy of LAI with in-line chemical amendment of CS water and irrigation with non-saline, non-sodic and non-alkaline (good quality) water under field conditions in southern Queensland. Soil chemical properties, soluble Ca, Mg, K, Na, electrical conductivity (EC), pH, chloride and alkalinity, as well as saturated hydraulic conductivity were measured to determine the impact of the irrigation treatments on soil chemical and physical conditions. Irrigation of lucerne pasture using solid-set sprinklers applied a total of 6.7 ML/ha of each treatment irrigation water to the experimental plots over a 10-month period. Alkalinity was neutralised using LAI, with no increase in soil alkalinity observed. Soil sodicity did not exceed threshold electrolyte concentration values under either CS water irrigation treatment. Soil chemical and physical properties were comparable for both LAI and in-line chemical amendment of CS water. Soil saturated hydraulic conductivity was maintained under all irrigation treatments. Results showed that the constrained capacity of the irrigation system was unable to meet crop evapotranspiration demand. This resulted in accumulation of salt within the root-zone under the CS water treatments compared to the good quality water treatment. LAI successfully chemically amended Bowen Basin CS water facilitating its beneficial use for agricultural irrigation.

  6. Alkaline nanoparticle coatings improve resin bonding of 10-methacryloyloxydecyldihydrogenphosphate-conditioned zirconia.

    PubMed

    Qian, Mengke; Lu, Zhicen; Chen, Chen; Zhang, Huaiqin; Xie, Haifeng

    Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular. Thermodynamics calculations were performed to evaluate the strengths of MDP-tetragonal phase zirconia chemical bonds at different pH values. Zirconia surfaces with and without alkaline coatings were characterized by scanning electron microscope (SEM)/energy dispersive spectrometer and Fourier transform infrared spectroscopy; alkaline coatings included NaOH, Ca(OH)2, nano-MgO, and nano-Zr(OH)4. A shear bond strength (SBS) test was performed to evaluate the effects of the four alkaline coatings on bonding; the alkaline coatings were applied to the surfaces prior to conditioning the zirconia with MDP-containing primers. Gibbs free energies of the MDP-tetragonal zirconia crystal model coordination reaction in different pH environments were -583.892 (NaOH), -569.048 [Ca(OH)2], -547.393 (MgO), and -530.279 kJ/mol [Zr(OH)4]. Thermodynamic calculations indicated that the alkaline coatings improved bonding in the following order: NaOH > Ca(OH)2 > MgO > Zr(OH)4. Statistical analysis of SBS tests showed a different result. SBSs were significantly different in groups that had different alkaline coatings, but it was not influenced by different primers. All four alkaline coatings increased SBS compared to control groups. Of the four coatings, nano-Zr(OH)4 and -MgO showed higher SBS. Therefore, preparing nano-Zr(OH)4 or -MgO coatings prior to conditioning with MDP-containing primers may potentially improve resin bonding of zirconia in the clinic.

  7. Alkaline nanoparticle coatings improve resin bonding of 10-methacryloyloxydecyldihydrogenphosphate-conditioned zirconia

    PubMed Central

    Qian, Mengke; Lu, Zhicen; Chen, Chen; Zhang, Huaiqin; Xie, Haifeng

    2016-01-01

    Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular. Thermodynamics calculations were performed to evaluate the strengths of MDP-tetragonal phase zirconia chemical bonds at different pH values. Zirconia surfaces with and without alkaline coatings were characterized by scanning electron microscope (SEM)/energy dispersive spectrometer and Fourier transform infrared spectroscopy; alkaline coatings included NaOH, Ca(OH)2, nano-MgO, and nano-Zr(OH)4. A shear bond strength (SBS) test was performed to evaluate the effects of the four alkaline coatings on bonding; the alkaline coatings were applied to the surfaces prior to conditioning the zirconia with MDP-containing primers. Gibbs free energies of the MDP-tetragonal zirconia crystal model coordination reaction in different pH environments were −583.892 (NaOH), −569.048 [Ca(OH)2], −547.393 (MgO), and −530.279 kJ/mol [Zr(OH)4]. Thermodynamic calculations indicated that the alkaline coatings improved bonding in the following order: NaOH > Ca(OH)2 > MgO > Zr(OH)4. Statistical analysis of SBS tests showed a different result. SBSs were significantly different in groups that had different alkaline coatings, but it was not influenced by different primers. All four alkaline coatings increased SBS compared to control groups. Of the four coatings, nano-Zr(OH)4 and -MgO showed higher SBS. Therefore, preparing nano-Zr(OH)4 or -MgO coatings prior to conditioning with MDP-containing primers may potentially improve resin bonding of zirconia in the clinic. PMID:27785013

  8. Production of alkaline protease from Cellulosimicrobium cellulans

    PubMed Central

    Ferracini-Santos, Luciana; Sato, Hélia H

    2009-01-01

    Cellulosimicrobium cellulans is one of the microorganisms that produces a wide variety of yeast cell wall-degrading enzymes, β-1,3-glucanase, protease and chitinase. Dried cells of Saccharomyces cerevisiae were used as carbon and nitrogen source for cell growth and protease production. The medium components KH2PO4, KOH and dried yeast cells showed a significant effect (p<0.05) on the factorial fractional design. A second design was prepared using two factors: pH and percentage of dried yeast cells. The results showed that the culture medium for the maximum production of protease was 0.2 g/l of MgSO4.7H2O, 2.0 g/l of (NH4)2SO4 and 8% of dried yeast cells in 0.15M phosphate buffer at pH 8.0. The maximum alkaline protease production was 7.0 ± 0.27 U/ml over the center point. Crude protease showed best activity at 50ºC and pH 7.0-8.0, and was stable at 50ºC. PMID:24031317

  9. Extracellular Alkalinization as a Defense Response in Potato Cells

    PubMed Central

    Moroz, Natalia; Fritch, Karen R.; Marcec, Matthew J.; Tripathi, Diwaker; Smertenko, Andrei; Tanaka, Kiwamu

    2017-01-01

    A quantitative and robust bioassay to assess plant defense response is important for studies of disease resistance and also for the early identification of disease during pre- or non-symptomatic phases. An increase in extracellular pH is known to be an early defense response in plants. In this study, we demonstrate extracellular alkalinization as a defense response in potatoes. Using potato suspension cell cultures, we observed an alkalinization response against various pathogen- and plant-derived elicitors in a dose- and time-dependent manner. We also assessed the defense response against a variety of potato pathogens, such as protists (Phytophthora infestans and Spongospora subterranea) and fungi (Verticillium dahliae and Colletotrichum coccodes). Our results show that extracellular pH increases within 30 min in proportion to the number of pathogen spores added. Consistently with the alkalinization effect, the higher transcription level of several defense-related genes and production of reactive oxygen species was observed. Our results demonstrate that the alkalinization response is an effective marker to study early stages of defense response in potatoes. PMID:28174578

  10. Extracellular Alkalinization as a Defense Response in Potato Cells.

    PubMed

    Moroz, Natalia; Fritch, Karen R; Marcec, Matthew J; Tripathi, Diwaker; Smertenko, Andrei; Tanaka, Kiwamu

    2017-01-01

    A quantitative and robust bioassay to assess plant defense response is important for studies of disease resistance and also for the early identification of disease during pre- or non-symptomatic phases. An increase in extracellular pH is known to be an early defense response in plants. In this study, we demonstrate extracellular alkalinization as a defense response in potatoes. Using potato suspension cell cultures, we observed an alkalinization response against various pathogen- and plant-derived elicitors in a dose- and time-dependent manner. We also assessed the defense response against a variety of potato pathogens, such as protists (Phytophthora infestans and Spongospora subterranea) and fungi (Verticillium dahliae and Colletotrichum coccodes). Our results show that extracellular pH increases within 30 min in proportion to the number of pathogen spores added. Consistently with the alkalinization effect, the higher transcription level of several defense-related genes and production of reactive oxygen species was observed. Our results demonstrate that the alkalinization response is an effective marker to study early stages of defense response in potatoes.

  11. The catalytic properties of alkaline phosphatases under various conditions

    NASA Astrophysics Data System (ADS)

    Atyaksheva, L. F.; Chukhrai, E. S.; Poltorak, O. M.

    2008-11-01

    A comparative study was performed to examine the catalytic properties of alkaline phosphatases from bacteria Escherichia coli and bovine and chicken intestines. The activity of enzyme dimers and tetramers was determined. The activity of the dimer was three or four times higher than that of the tetramer. The maximum activity and affinity for 4-nitrophenylphosphate was observed for the bacterial alkaline phosphatase ( K M = 1.7 × 10-5 M, V max = 1800 μmol/(min mg of protein) for dimers and V max = 420 μmol/(min mg of protein) for tetramers). The Michaelis constants were equal for two animal phosphatases in various buffer media (pH 8.5) ((3.5 ± 0.2) × 10-4 M). Five buffer systems were investigated: tris, carbonate, hepes, borate, and glycine buffers, and the lowest catalytic activity of alkaline phosphatases at equal pH was observed in the borate buffer (for enzyme from bovine intestine, V max = 80 μmol/(min mg of protein)). Cu2+ cations formed a complex with tris-(oxymethyl)-aminomethane ( tris-HCl buffer) and inhibited the intestine alkaline phosphatases by a noncompetitive mechanism.

  12. Mammalian intestinal alkaline phosphatase acts as highly active exopolyphosphatase.

    PubMed

    Lorenz, B; Schröder, H C

    2001-06-11

    Recent results revealed that inorganic polyphosphates (polyP), being energy-rich linear polymers of orthophosphate residues known from bacteria and yeast, also exist in higher eukaryotes. However, the enzymatic basis of their metabolism especially in mammalian cells is still uncertain. Here we demonstrate for the first time that alkaline phosphatase from calf intestine (CIAP) is able to cleave polyP molecules up to a chain length of about 800. The enzyme acts as an exopolyphosphatase degrading polyP in a processive manner. The pH optimum is in the alkaline range. Divalent cations are not required for catalytic activity but inhibit the degradation of polyP. The rate of hydrolysis of short-chain polyP by CIAP is comparable to that of the standard alkaline phosphatase (AP) substrate p-nitrophenyl phosphate. The specific activity of the enzyme decreases with increasing chain length of the polymer both in the alkaline and in the neutral pH range. The K(m) of the enzyme also decreases with increasing chain length. The mammalian tissue non-specific isoform of AP was not able to hydrolyze polyP under the conditions applied while the placental-type AP and the bacterial (Escherichia coli) AP displayed polyP-degrading activity.

  13. Surfactant-enhanced alkaline flooding field project

    SciTech Connect

    French, T.R.

    1991-10-01

    The Tucker sand of Helper (KS) field is a candidate for surfactant-enhanced alkaline flooding. The geology of the Helper site is typical of many DOE Class I reservoirs. The Tucker sand of Helper field was deposited in a fluvial dominated deltaic environment. Helper oil can be mobilized with either chemical system 2 or chemical system 3, as described in this report. Oil fields in the Gulf Coast region are also good candidates for surfactant-enhanced alkaline flooding. The results from laboratory tests conducted in Berea sandstone cores with oil brine from Helper (KS) field are encouraging. The crude oil is viscous and non-acidic and, yet, was mobilized by the chemical formulations described in this report. Significant amounts of the oil were mobilized under simulated reservoir conditions. The results in Berea sandstone cores were encouraging and should be verified by tests with field core. Consumption of alkali, measured with field core, was very low. Surfactant loss appeared to be acceptable. Despite the good potential for mobilization of Helper oil, certain reservoir characteristics such as low permeability, compartmentalization, and shallow depth place constraints on applications of any chemical system in the Tucker sand. These constraints are typical of many DOE Class I reservoirs. Although Hepler field is not a perfect reservoir in which to apply surfactant- enhanced alkaline flooding, Hepler oil is particularly amenable to mobilization by surfactant-enhanced alkaline systems. A field test is recommended, dependent upon final evaluation of well logs and cores from the proposed pilot area. 14 refs., 21 figs., 10 tabs.

  14. Alkaline protease production by a strain of marine yeasts

    NASA Astrophysics Data System (ADS)

    Ping, Wang; Zhenming, Chi; Chunling, Ma

    2006-07-01

    Yeast strain 10 with high yield of protease was isolated from sediments of saltern near Qingdao, China. The protease had the highest activity at pH 9.0 and 45°C. The optimal medium for the maximum alkaline protease production of strain 10 was 2.5g soluble starch and 2.0g NaNO3 in 100mL seawater with initial pH 6.0. The optimal cultivation conditions for the maximum protease production were temperature 24.5°C, aeration rate 8.0L min-1 and agitation speed 150r min-1 Under the optimal conditions, 623.1 U mg-1 protein of alkaline protease was reached in the culture within 30h of fermentation.

  15. Escherichia coli alkaline phosphatase. Kinetic studies with the tetrameric enzyme.

    PubMed

    Halford, S E; Schlesinger, M J; Gutfreund, H

    1972-03-01

    1. The stability of the tetrameric form of Escherichia coli alkaline phosphatase was examined by analytical ultracentrifugation. 2. The stopped-flow technique was used to study the hydrolysis of nitrophenyl phosphates by the alkaline phosphatase tetramer at pH7.5 and 8.3. In both cases transient product formation was observed before the steady state was attained. Both transients consisted of the liberation of 1mol of nitrophenol/2mol of enzyme subunits within the dead-time of the apparatus. The steady-state rates were identical with those observed with the dimer under the same conditions. 3. The binding of 2-hydroxy-5-nitrobenzyl phosphonate to the alkaline phosphatase tetramer was studied by the temperature-jump technique. The self-association of two dimers to form the tetramer is linked to a conformation change within the dimer. This accounts for the differences between the transient phases in the reactions of the dimer and the tetramer with substrate. 4. Addition of P(i) to the alkaline phosphatase tetramer caused it to dissociate into dimers. The tetramer is unable to bind this ligand. It is suggested that the tetramer undergoes a compulsory dissociation before the completion of its first turnover with substrate. 5. On the basis of these findings a mechanism is proposed for the involvement of the alkaline phosphatase tetramer in the physiology of E. coli.

  16. Treatment of Alkaline Cr(VI)-Contaminated Leachate with an Alkaliphilic Metal-Reducing Bacterium

    PubMed Central

    Watts, Mathew P.; Khijniak, Tatiana V.; Boothman, Christopher

    2015-01-01

    Chromium in its toxic Cr(VI) valence state is a common contaminant particularly associated with alkaline environments. A well-publicized case of this occurred in Glasgow, United Kingdom, where poorly controlled disposal of a cementitious industrial by-product, chromite ore processing residue (COPR), has resulted in extensive contamination by Cr(VI)-contaminated alkaline leachates. In the search for viable bioremediation treatments for Cr(VI), a variety of bacteria that are capable of reduction of the toxic and highly soluble Cr(VI) to the relatively nontoxic and less mobile Cr(III) oxidation state, predominantly under circumneutral pH conditions, have been isolated. Recently, however, alkaliphilic bacteria that have the potential to reduce Cr(VI) under alkaline conditions have been identified. This study focuses on the application of a metal-reducing bacterium to the remediation of alkaline Cr(VI)-contaminated leachates from COPR. This bacterium, belonging to the Halomonas genus, was found to exhibit growth concomitant to Cr(VI) reduction under alkaline conditions (pH 10). Bacterial cells were able to rapidly remove high concentrations of aqueous Cr(VI) (2.5 mM) under anaerobic conditions, up to a starting pH of 11. Cr(VI) reduction rates were controlled by pH, with slower removal observed at pH 11, compared to pH 10, while no removal was observed at pH 12. The reduction of aqueous Cr(VI) resulted in the precipitation of Cr(III) biominerals, which were characterized using transmission electron microscopy and energy-dispersive X-ray analysis (TEM-EDX) and X-ray photoelectron spectroscopy (XPS). The effectiveness of this haloalkaliphilic bacterium for Cr(VI) reduction at high pH suggests potential for its use as an in situ treatment of COPR and other alkaline Cr(VI)-contaminated environments. PMID:26048926

  17. Treatment of Alkaline Cr(VI)-Contaminated Leachate with an Alkaliphilic Metal-Reducing Bacterium.

    PubMed

    Watts, Mathew P; Khijniak, Tatiana V; Boothman, Christopher; Lloyd, Jonathan R

    2015-08-15

    Chromium in its toxic Cr(VI) valence state is a common contaminant particularly associated with alkaline environments. A well-publicized case of this occurred in Glasgow, United Kingdom, where poorly controlled disposal of a cementitious industrial by-product, chromite ore processing residue (COPR), has resulted in extensive contamination by Cr(VI)-contaminated alkaline leachates. In the search for viable bioremediation treatments for Cr(VI), a variety of bacteria that are capable of reduction of the toxic and highly soluble Cr(VI) to the relatively nontoxic and less mobile Cr(III) oxidation state, predominantly under circumneutral pH conditions, have been isolated. Recently, however, alkaliphilic bacteria that have the potential to reduce Cr(VI) under alkaline conditions have been identified. This study focuses on the application of a metal-reducing bacterium to the remediation of alkaline Cr(VI)-contaminated leachates from COPR. This bacterium, belonging to the Halomonas genus, was found to exhibit growth concomitant to Cr(VI) reduction under alkaline conditions (pH 10). Bacterial cells were able to rapidly remove high concentrations of aqueous Cr(VI) (2.5 mM) under anaerobic conditions, up to a starting pH of 11. Cr(VI) reduction rates were controlled by pH, with slower removal observed at pH 11, compared to pH 10, while no removal was observed at pH 12. The reduction of aqueous Cr(VI) resulted in the precipitation of Cr(III) biominerals, which were characterized using transmission electron microscopy and energy-dispersive X-ray analysis (TEM-EDX) and X-ray photoelectron spectroscopy (XPS). The effectiveness of this haloalkaliphilic bacterium for Cr(VI) reduction at high pH suggests potential for its use as an in situ treatment of COPR and other alkaline Cr(VI)-contaminated environments.

  18. Sensitivity of mitomycin C and nitrogen mustard crosslinks to extreme alkaline conditions

    SciTech Connect

    Gruenert, D.C.; Cleaver, J.E.

    1984-09-17

    DNA-DNA crosslinks in cells treated with mitomycin C, nitrogen mustard, or decarbamoyl mitomycin C were measured in alkaline isopycnic gradients as a function of pH. Crosslinks from cells treated with mitomycin C and nitrogen mustard, which react with DNA purines, could be detected at pH 12.5 but not at pH 14. No crosslinks from cells treated with decarbamoyl mitomycin C were detected at either pH. Previous studies with cells exposed to psoralen derivatives plus 360 nm light, which produce DNA-DNA crosslinks with pyrimidines, demonstrated stable crosslinks at pH 14. These studies indicate that DNA-DNA crosslinks involving DNA purines are much less stable at high pH than those involving pyrimidines, and that methods involving exposure to extreme alkaline conditions may give inaccurate information for some agents. 25 references, 1 figure.

  19. Ocean Acidification: Coccolithophore's Light Controlled Effect on Alkalinity

    NASA Astrophysics Data System (ADS)

    Dobbins, W.

    2015-12-01

    Coccolithophorids, which play a significant role in the flux of calcite and organic carbon from the photic region to deeper pelagic and benthic zones, are potentially far more useful than siliceous phytoplankton for ocean fertilization projects designed to sequester CO2. However, the production of H+ ions during calcification (HCO3 + Ca+ —> CaCO3 + H+) has resulted in localized acidification around coccolithophore blooms. It has been hypothesized that under the correct light conditions photosynthesis could proceed at a rate such that CO2 is removed in amounts equimolar or greater than the H+ produced by calcification, allowing stable or increasing alkalinity despite ongoing calcification. Previously, this effect had not been demonstrated under laboratory conditions. Fifteen Emiliania huxleyi cultures were separated into equal groups with each receiving: 0, 6, 12, 18, or 24 hours of light each day for 24 days. Daily pH, cell density, and temperature measurements revealed a strong positive correlation between light exposure and pH, and no significant decline in pH in any of the cultures. Alkalinity increases were temperature independent and not strongly correlated with cell density, implying photosynthetic removal of carbon dioxide as the root cause. The average pH across living cultures increased from 7.9 to 8.3 over the first week and changed little for the reminder of the 24-day period. The results demonstrate coccolithophorids can increase alkalinity across a broad range of cell densities, despite the acidification inherent to the calcification process. If the light-alkalinity effect reported here proves scalable to larger cultures, Emiliania huxleyi are a strong candidate for carbon sequestration via targeted ocean fertilization.

  20. The alkaline and alkaline-carbonatite magmatism from Southern Brazil

    NASA Astrophysics Data System (ADS)

    Ruberti, E.; Gomes, C. D. B.; Comin-Chiaramonti, P.

    2015-12-01

    Early to Late Cretaceous lasting to Paleocene alkaline magmatism from southern Brazil is found associated with major extensional structural features in and around the Paraná Basin and grouped into various provinces on the basis of several data. Magmatism is variable in size, mode of occurrence and composition. The alkaline rocks are dominantly potassic, a few occurrences showing sodic affinity. The more abundant silicate rocks are evolved undersaturated to saturated in silica syenites, displaying large variation in igneous forms. Less evolved types are restricted to subvolcanic environments and outcrops of effusive suites occur rarely. Cumulatic mafic and ultramafic rock types are very common, particularly in the alkali-carbonatitic complexes. Carbonatite bodies are represented by Ca-carbonatites and Mg-carbonatites and more scarcely by Fe-carbonatites. Available radiometric ages for the alkaline rocks fit on three main chronological groups: around 130 Ma, subcoveal with the Early Cretaceous flood tholeiites of the Paraná Basin, 100-110 Ma and 80-90 Ma (Late Cretaceous). The alkaline magmatism also extends into Paleocene times, as indicated by ages from some volcanic lavas. Geochemically, alkaline potassic and sodic rock types are distinguished by their negative and positive Nb-Ta anomalies, respectively. Negative spikes in Nb-Ta are also a feature common to the associated tholeiitic rocks. Sr-Nd-Pb systematics confirm the contribution of both HIMU and EMI mantle components in the formation of the alkaline rocks. Notably, Early and Late Cretaceous carbonatites have the same isotopic Sr-Nd initial ratios of the associated alkaline rocks. C-O isotopic Sr-Nd isotopic ratios indicate typical mantle signature for some carbonatites and the influence of post-magmatic processes in others. Immiscibility of liquids of phonolitic composition, derived from mafic alkaline parental magmas, has been responsible for the origin of the carbonatites. Close association of alkaline

  1. [Contrastive analysis on soil alkalinization predicting models based on measured reflectance and TM image reflectance].

    PubMed

    Zhang, Fang; Xiong, Hei-Gang; Long, Tao; Lu, Wen-Juan

    2011-01-01

    Based on the monitored data of soil pH and measured Vis-NIR reflectance on spot in Qitai oasis alkalinized area in Xinjiang, as well as comparison of the relationship between measured reflectance and soil pH and the relationship between TM reflectance and soil pH, both of the reflectance multivariate linear regression models were built to evaluate soil alkalinization level, and the model accuracy of pH fitting was discussed with error inspection of post-sample. The results showed that there is a significant positive correlation between soil pH and reflectance. With pH rising the reflectance increased concurrently. So the alkalinization soil characterized by hardening had good spectral response characteristics. Both measured reflectance and TM image reflectance had good potential ability for change detection of the alkalinization soil. The pH predicting model of measured reflectance had higher accuracy and the major error was from different hardening state. If building model by TM reflectance directly, the accuracy of fitting was lower because of the vegetation information in image spectrum. With the vegetation factor removed with NDVI, the accuracy of TM predicting model was near the accuracy of measured reflectance predicting model, and both of the model levels were good.

  2. Alkaline buffers release EDRF from bovine cultured aortic endothelial cells.

    PubMed Central

    Mitchell, J. A.; de Nucci, G.; Warner, T. D.; Vane, J. R.

    1991-01-01

    1. Release of endothelium-derived relaxing factor (EDRF) and prostacyclin (PGI2) from bovine cultured aortic endothelial cells (EC) was measured by bioassay and radioimmunoassay, respectively. 2. Bradykinin (BK, 3-30 pmol), adenosine diphosphate (ADP, 2-6 nmol) or the sodium ionophore monensin (40-100 nmol) injected through a column of EC released EDRF. L-Arginine free base (FB; 10-20 mumol) or D-arginine FB (10-20 mumol) injected through the column of EC released similar amounts of EDRF and also caused an increase in pH of the Krebs solution perfusing the EC from 7.5-8.0 to 8.6-9.5. Sodium carbonate (Na2CO3) an alkaline buffer which caused the same changes in the pH of the Krebs solution also induced the same release of EDRF. The hydrochloride salts of L- or D-arginine did not cause either release of EDRF when injected through the column of EC or increases in the pH of the Krebs solution. 3. Inhibitors of either diacylglycerol lipase (RHC 80267) or kinase (R59022) inhibited the release of EDRF induced by BK or ADP but potentiated the release induced by L-arginine FB, monensin (40-100 nmol) or alkaline buffer (Na2CO3). R59022 and RHC 80267 infused through the EC increased the basal release of EDRF. 4. When calcium chloride was omitted from the Krebs solution the release of EDRF induced by alkaline buffer (Na2CO3; pH 8.6-9.5) or L-arginine FB (10-20 mumol) was selectively inhibited when compared to that induced by BK (3-30 pmol) or ADP (2-6 nmol). This inhibition was reversed when calcium (2.5 mM) was restored. 5. NG-monomethyl-L-arginine (NMMA; 30 microM) inhibited release of EDRF induced by BK (10-30 pmol) or alkaline buffers (Na2CO3 or D-arginine FB; pH 8.6-9.5). This inhibition was partially reversed by L- but not D-arginine FB or HCl (30-100 microM). 6. Prostacyclin was released when BK (10 pmol), ADP (2 nmol) or arachidonic acid (30 nmol) were injected through the column of EC. However, monensin (40 nmol) or alkaline buffers (pH 8.6-9.5) did not release

  3. Phosphotyrosine as a substrate of acid and alkaline phosphatases.

    PubMed

    Apostoł, I; Kuciel, R; Wasylewska, E; Ostrowski, W S

    1985-01-01

    A new spectrophotometric method for following dephosphorylation of phosphotyrosine has been described. The absorption spectra of phosphotyrosine and tyrosine were plotted over the pH range from 3 to 9. The change in absorbance accompanying the conversion of phosphotyrosine to tyrosine was the greatest at 286 nm. The difference absorption coefficients were calculated for several pH values. Dephosphorylation of phosphotyrosine by acid phosphatases from human prostate gland, from wheat germ and potatoes obeys the Michaelis-Menten equation, whereas alkaline phosphatases calf intestine and E. coli are inhibited by excess of substrate.

  4. Dissociation energies of PH and PH+.

    NASA Astrophysics Data System (ADS)

    Reddy, R. R.; Nazeer Ahammed, Y.; Srinivasa Rao, A.; Rao, T. V. R.

    1995-12-01

    Dissociation energies for the ground electronic states of diatomic PH and PH+ are determined by fitting empirical potential functions to the respective RKRV curves using correlation coefficients. The estimated ground state dissociation energies of PH and PH+ are 3.10 and 3.20 eV respectively by the curve fitting procedure using the Lippincott potential function. The computed values are in good agreement with experimental values.

  5. Priming effect of abscisic acid on alkaline stress tolerance in rice (Oryza sativa L.) seedlings.

    PubMed

    Wei, Li-Xing; Lv, Bing-Sheng; Wang, Ming-Ming; Ma, Hong-Yuan; Yang, Hao-Yu; Liu, Xiao-Long; Jiang, Chang-Jie; Liang, Zheng-Wei

    2015-05-01

    Saline-alkaline stress is characterized by high salinity and high alkalinity (high pH); alkaline stress has been shown to be the primary factor inhibiting rice seedling growth. In this study, we investigated the potential priming effect of abscisic acid (ABA) on tolerance of rice seedlings to alkaline stress simulated by Na2CO3. Seedlings were pretreated with ABA at concentrations of 0 (control), 10, and 50 μM by root-drench for 24 h and then transferred to a Na2CO3 solution that did not contain ABA. Compared to control treatment, pretreatment with ABA substantially improved the survival rate of rice seedlings and increased biomass accumulation after 7 days under the alkaline condition. ABA application at 10 μM also alleviated the inhibitory effects of alkaline stress on the total root length and root surface area. Physiologically, ABA increased relative water content (RWC) and decreased cell membrane injury degree (MI) and Na(+)/K(+) ratios. In contrast, fluridone (an ABA biosynthesis inhibitor) decreased the RWC and increased MI in shoots under the alkaline conditions. These data suggest that ABA has a potent priming effect on the adaptive response to alkaline stress in rice and may be useful for improving rice growth in saline-alkaline paddy fields.

  6. Microbial Thiocyanate Utilization under Highly Alkaline Conditions

    PubMed Central

    Sorokin, Dimitry Y.; Tourova, Tatyana P.; Lysenko, Anatoly M.; Kuenen, J. Gijs

    2001-01-01

    Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS−) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase

  7. Properties of whey protein isolates extruded under acidic and alkaline conditions.

    PubMed

    Onwulata, C I; Isobe, S; Tomasula, P M; Cooke, P H

    2006-01-01

    Whey proteins have wide acceptance and use in many products due to their beneficial nutritional properties. To further increase the amount of whey protein isolates (WPI) that may be added to products such as extruded snacks and meats, texturization of WPI is necessary. Texturization changes the folding of globular proteins to improve interaction with other ingredients and create new functional ingredients. In this study, WPI pastes (60% solids) were extruded in a twin-screw extruder at 100 degrees C with 4 pH-adjusted water streams: acidic (pH 2.0 +/- 0.2) and alkaline (pH 12.4 +/- 0.4) streams from 2 N HCl and 2 N NaOH, respectively, and acidic (pH 2.5 +/- 0.2) and alkaline (pH 11.5 +/- 0.4) electrolyzed water streams; these were compared with WPI extruded with deionized water. The effects of water acidity on WPI solubility at pH 7, color, microstructure, Rapid Visco Analyzer pasting properties, and physical structure were determined. Alkaline conditions increased insolubility caused yellowing and increased pasting properties significantly. Acidic conditions increased solubility and decreased WPI pasting properties. Subtle structural changes occurred under acidic conditions, but were more pronounced under alkaline conditions. Overall, alkaline conditions increased denaturation in the extruded WPI resulting in stringy texturized WPI products, which could be used in meat applications.

  8. Dephosphorylation of bovine casein by milk alkaline phosphatase.

    PubMed

    Lorient, D; Linden, G

    1976-02-01

    The pH of optimum activity of alkaline phosphatase from cow's milk depended on the substrate, being 10-1 for rho-nitrophenylphosphate, 8-6 for phosphoserine, 8-0 for phosvitin and 6-8 for casein. Individual casein components were dephosphorylated more rapidly than mixtures of alphas- and beta-caseins or of alphas-, beta-and kappa-caseins and micellar casein. Mixtures of 2 components involving kappa-casein were more readily dephosphorylated than alphas- and beta-casein mixtures. At pH 6-8, lactose, whey proteins and phosphate ions had an inhibitory effect. beta-Lactoglobulin had an inhibitory effect only when the pH of the reaction was lower than the optimum pH value of the enzyme. Mg2+ and Zn2+ were not inhibitory. The optimum conditions for dephosphorylation of casein are described.

  9. Dolomite Dissolution in Alkaline Cementious Media

    NASA Astrophysics Data System (ADS)

    Mittermayr, Florian; Klammer, Dietmar; Köhler, Stephan; Dietzel, Martin

    2010-05-01

    Chemical alteration of concrete has gained much attention over the past years as many cases of deterioration due to sulphate attack, thaumasite formation (TSA) or alkali silica reactions (ASR) have been reported in various constructions (Schmidt et al, 2009). Much less is known about the so called alkali carbonate reaction (ACR). It is believed that dolomite aggregates can react with the alkalis from the cement, dissolve and form calcite and brucite (Katayama, 2004). Due to very low solubility of dolomite in alkaline solutions this reaction seems doubtful. In this study we are trying to gain new insides about the conditions that can lead to the dissolution of dolomite in concrete. Therefore we investigated concrete samples from Austrian tunnels that show partially dissolved dolomite aggregates. Petrological analysis such as microprobe, SEM and Raman spectroscopy as well as a hydrochemical analysis of interstitial solutions and ground water and modelling with PhreeqC (Parkhurst and Appelo, 1999) are carried out. In addition a series of batch experiments is set up. Modelling approaches by PhreeqC show a thermodynamically possibility in the alkaline range when additional Ca2+ in solution causes dolomite to become more and more undersaturated as calcite gets supersaturated. Interacting ground water is enriched in Ca2+and saturated with respect to gypsum as marine evaporites are found in situ rocks. Furthermore it is more likely that Portlandite (Ca(OH)2) plays a more important role than Na and K in the cement. Portlandite acts as an additional Ca2+ source and is much more abundant than the alkalies. Some interstitial solutions are dominated mainly by Na+ and SO42- and reach concentrations up to 30 g/l TDS. It is believed that solutions can even reach thenardite saturation as efflorescences are found on the tunnel walls. In consequence dolomite solubility increases with increasing ionic strength. pH > 11 further accelerate the process of dedolomitization by the removal

  10. Increased performance of hydrogen production in microbial electrolysis cells under alkaline conditions.

    PubMed

    Rago, Laura; Baeza, Juan A; Guisasola, Albert

    2016-06-01

    This work reports the first successful enrichment and operation of alkaline bioelectrochemical systems (microbial fuel cells, MFC, and microbial electrolysis cells, MEC). Alkaline (pH=9.3) bioelectrochemical hydrogen production presented better performance (+117%) compared to conventional neutral conditions (2.6 vs 1.2 litres of hydrogen gas per litre of reactor per day, LH2·L(-1)REACTOR·d(-1)). Pyrosequencing results of the anodic biofilm showed that while Geobacter was mainly detected under conventional neutral conditions, Geoalkalibacter sp. was highly detected in the alkaline MFC (21%) and MEC (48%). This is the first report of a high enrichment of Geoalkalibacter from an anaerobic mixed culture using alkaline conditions in an MEC. Moreover, Alkalibacter sp. was highly present in the anodic biofilm of the alkaline MFC (37%), which would indicate its potentiality as a new exoelectrogen.

  11. Surfactant-enhanced alkaline flooding for light oil recovery. Final report 1994--1995

    SciTech Connect

    Wasan, D.T.

    1995-12-01

    In this report, the authors present the results of their experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, the authors have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil, and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are summarized.

  12. Surfactant-enhanced alkaline flooding for light oil recovery. Final report

    SciTech Connect

    Wasan, D.T.

    1996-05-01

    In this report, we present the results of our experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12. 0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, we have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are discussed.

  13. Pathway and mechanism of pH dependent human hemoglobin tetramer-dimer-monomer dissociations.

    PubMed

    Huang, Yao-Xiong; Wu, Zheng-Jie; Huang, Bao-Tian; Luo, Man

    2013-01-01

    Hemoglobin dissociation is of great interest in protein process and clinical medicine as well as in artificial blood research. However, the pathway and mechanisms of pH-dependent human Hb dissociation are not clear, whether Hb would really dissociate into monomers is still a question. Therefore, we have conducted a multi-technique investigation on the structure and function of human Hb versus pH. Here we demonstrate that tetramer hemoglobin can easily dissociate into dimer in abnormal pH and the tetramer → dimer dissociation is reversible if pH returns to normal physiological value. When the environmental pH becomes more acidic (<6.5) or alkaline (>8.0), Hb can further dissociate from dimer to monomer. The proportion of monomers increases while the fraction of dimers decreases as pH declines from 6.2 to 5.4. The dimer → monomer dissociation is accompanied with series changes of protein structure thus it is an irreversible process. The structural changes in the dissociated Hbs result in some loss of their functions. Both the Hb dimer and monomer cannot adequately carry and release oxygen to the tissues in circulation. These findings provide a comprehensive understanding on the pH-dependent protein transitions of human Hb, give guideline to explain complex protein processes and the means to control protein dissociation or re-association reaction. They are also of practical value in clinical medicine, blood preservation and blood substitute development.

  14. Solubility of ion and trace metals from stabilized sewage sludge by fly ash and alkaline mine tailing.

    PubMed

    Zhang, Hongling; Sun, Lina; Sun, Tieheng

    2008-01-01

    Stabilized sewage sludge (SS) by fly ash (FA) and alkaline mine tailing as artificial soil, to be applied on the ecological rehabilitation at mining junkyards, offers a potentially viable utilization of the industrial by-product, as well as solves the shortage of soil resource in the mine area. An incubation experiment with different ratios of SS and FA was conducted to evaluate the solubility of ions and trace elements from stabilized sewage sludge. Results showed that fly ash offset a decrease in pH value of sewage sludge. The pH of (C) treatment (FA:SS = 1:1) was stable and tended to neutrality. The SO4(2-) and Cl- concentrations of the solution in the mixture were significantly decreased in the stabilized sewage sludge by alkaline fly ash and mine tailing, compared to the single SS treatment. Stabilized sewage sludge by FA weakened the nitrification of total nitrogen from SS when the proportion of FA in the mixture was more than 50%. The Cr, Ni, and Cu concentrations in the solution were gradually decreased and achieved a stable level after 22 days, for all treatments over the duration of the incubation. Moreover stabilized sewage sludge by fly ash and/or mine tailing notably decreased the trace metal solubility. The final Cr, Cu, and Ni concentrations in the solution for all mixtures of treatments were lower than 2.5, 15, and 50 microg/L, respectively.

  15. Effect of alkalinity on nitrite accumulation in treatment of coal chemical industry wastewater using moving bed biofilm reactor.

    PubMed

    Hou, Baolin; Han, Hongjun; Jia, Shengyong; Zhuang, Haifeng; Zhao, Qian; Xu, Peng

    2014-05-01

    Nitrogen removal via nitrite (the nitrite pathway) is more suitable for carbon-limited industrial wastewater. Partial nitrification to nitrite is the primary step to achieve nitrogen removal via nitrite. The effect of alkalinity on nitrite accumulation in a continuous process was investigated by progressively increasing the alkalinity dosage ratio (amount of alkalinity to ammonia ratio, mol/mol). There is a close relationship among alkalinity, pH and the state of matter present in aqueous solution. When alkalinity was insufficient (compared to the theoretical alkalinity amount), ammonia removal efficiency increased first and then decreased at each alkalinity dosage ratio, with an abrupt removal efficiency peak. Generally, ammonia removal efficiency rose with increasing alkalinity dosage ratio. Ammonia removal efficiency reached to 88% from 23% when alkalinity addition was sufficient. Nitrite accumulation could be achieved by inhibiting nitrite oxidizing bacteria (NOB) by free ammonia (FA) in the early period and free nitrous acid in the later period of nitrification when alkalinity was not adequate. Only FA worked to inhibit the activity of NOB when alkalinity addition was sufficient.

  16. Systemic and local effects of long-term exposure to alkaline drinking water in rats.

    PubMed

    Merne, M E; Syrjänen, K J; Syrjänen, S M

    2001-08-01

    Alkaline conditions in the oral cavity may be caused by a variety of stimuli, including tobacco products, antacids, alkaline drinking water or bicarbonate toothpaste. The effects of alkaline pH on oral mucosa have not been systematically studied. To assess the systemic (organ) and local (oral mucosal) effects of alkalinity, drinking water supplemented with Ca(OH)2 or NaOH, with pH 11.2 or 12 was administered to rats (n = 36) for 52 weeks. Tissues were subjected to histopathological examination; oral mucosal biopsy samples were also subjected to immunohistochemical (IHC) analyses for pankeratin, CK19, CK5, CK4, PCNA, ICAM-1, CD44, CD68, S-100, HSP 60, HSP70, and HSP90. At completion of the study, animals in the study groups had lower body weights (up to 29% less) than controls despite equal food and water intake, suggesting a systemic response to the alkaline treatment. The lowest body weight was found in rats exposed to water with the highest pH value and starting the experiment when young (6 weeks). No histological changes attributable to alkaline exposure occurred in the oral mucosa or other tissues studied. Alkaline exposure did not affect cell proliferation in the oral epithelium, as shown by the equal expression of PCNA in groups. The up-regulation of HSP70 protein expression in the oral mucosa of rats exposed to alkaline water, especially Ca(OH)2 treated rats, may indicate a protective response. Intercellular adhesion molecule-1 (ICAM-1) positivity was lost in 6/12 rats treated with Ca(OH)2 with pH 11.2, and loss of CD44 expression was seen in 3/6 rats in both study groups exposed to alkaline water with pH 12. The results suggest that the oral mucosa in rats is resistant to the effects of highly alkaline drinking water. However, high alkalinity may have some unknown systemic effects leading to growth retardation, the cause of which remains to be determined.

  17. Systemic and local effects of long-term exposure to alkaline drinking water in rats

    PubMed Central

    Merne, Marina ET; Syrjänen, Kari J; Syrjänen, Stina M

    2001-01-01

    Alkaline conditions in the oral cavity may be caused by a variety of stimuli, including tobacco products, antacids, alkaline drinking water or bicarbonate toothpaste. The effects of alkaline pH on oral mucosa have not been systematically studied. To assess the systemic (organ) and local (oral mucosal) effects of alkalinity, drinking water supplemented with Ca(OH)2 or NaOH, with pH 11.2 or 12 was administered to rats (n = 36) for 52 weeks. Tissues were subjected to histopathological examination; oral mucosal biopsy samples were also subjected to immunohistochemical (IHC) analyses for pankeratin, CK19, CK5, CK4, PCNA, ICAM-1, CD44, CD68, S-100, HSP 60, HSP70, and HSP90. At completion of the study, animals in the study groups had lower body weights (up to 29% less) than controls despite equal food and water intake, suggesting a systemic response to the alkaline treatment. The lowest body weight was found in rats exposed to water with the highest pH value and starting the experiment when young (6 weeks). No histological changes attributable to alkaline exposure occurred in the oral mucosa or other tissues studied. Alkaline exposure did not affect cell proliferation in the oral epithelium, as shown by the equal expression of PCNA in groups. The up-regulation of HSP70 protein expression in the oral mucosa of rats exposed to alkaline water, especially Ca(OH)2 treated rats, may indicate a protective response. Intercellular adhesion molecule-1 (ICAM-1) positivity was lost in 6/12 rats treated with Ca(OH)2 with pH 11.2, and loss of CD44 expression was seen in 3/6 rats in both study groups exposed to alkaline water with pH 12. The results suggest that the oral mucosa in rats is resistant to the effects of highly alkaline drinking water. However, high alkalinity may have some unknown systemic effects leading to growth retardation, the cause of which remains to be determined. PMID:11493345

  18. Process for treating alkaline wastes for vitrification

    SciTech Connect

    Hsu, Chia-lin W.

    1994-01-01

    According to its major aspects and broadly stated, the present invention is a process for treating alkaline waste materials, including high level radioactive wastes, for vitrification. The process involves adjusting the pH of the wastes with nitric acid, adding formic acid (or a process stream containing formic acid) to reduce mercury compounds to elemental mercury and MnO{sub 2} to the Mn(II) ion, and mixing with class formers to produce a melter feed. The process minimizes production of hydrogen due to noble metal-catalyzed formic acid decomposition during, treatment, while producing a redox-balanced feed for effective melter operation and a quality glass product. An important feature of the present invention is the use of different acidifying and reducing, agents to treat the wastes. The nitric acid acidifies the wastes to improve yield stress and supplies acid for various reactions; then the formic acid reduces mercury compounds to elemental mercury and MnO{sub 2}) to the Mn(II) ion. When the pH of the waste is lower, reduction of mercury compounds and MnO{sub 2}) is faster and less formic acid is needed, and the production of hydrogen caused by catalytically-active noble metals is decreased.

  19. Response of Desulfovibrio vulgaris to Alkaline Stress

    SciTech Connect

    Stolyar, S.; He, Q.; He, Z.; Yang, Z.; Borglin, S.E.; Joyner, D.; Huang, K.; Alm, E.; Hazen, T.C.; Zhou, J.; Wall, J.D.; Arkin, A.P.; Stahl, D.A.

    2007-11-30

    The response of exponentially growing Desulfovibrio vulgarisHildenborough to pH 10 stress was studied using oligonucleotidemicroarrays and a study set of mutants with genes suggested by microarraydata to be involved in the alkaline stress response deleted. The datashowed that the response of D. vulgaris to increased pH is generallysimilar to that of Escherichia coli but is apparently controlled byunique regulatory circuits since the alternative sigma factors (sigma Sand sigma E) contributing to this stress response in E. coli appear to beabsent in D. vulgaris. Genes previously reported to be up-regulated in E.coli were up-regulated in D. vulgaris; these genes included three ATPasegenes and a tryptophan synthase gene. Transcription of chaperone andprotease genes (encoding ATP-dependent Clp and La proteases and DnaK) wasalso elevated in D. vulgaris. As in E. coli, genes involved in flagellumsynthesis were down-regulated. The transcriptional data also identifiedregulators, distinct from sigma S and sigma E, that are likely part of aD. vulgaris Hildenborough-specific stress response system.Characterization of a study set of mutants with genes implicated inalkaline stress response deleted confirmed that there was protectiveinvolvement of the sodium/proton antiporter NhaC-2, tryptophanase A, andtwo putative regulators/histidine kinases (DVU0331 andDVU2580).

  20. Alkalinity production in intertidal sands intensified by lugworm bioirrigation

    PubMed Central

    Rao, Alexandra M.F.; Malkin, Sairah Y.; Montserrat, Francesc; Meysman, Filip J.R.

    2014-01-01

    Porewater profiles and sediment-water fluxes of oxygen, nutrients, pH, calcium, alkalinity, and sulfide were measured in intertidal sandflat sediments from the Oosterschelde mesotidal lagoon (The Netherlands). The influence of bioturbation and bioirrigation by the deep-burrowing polychaete Arenicola marina on the rates and sources of benthic alkalinity generation was examined by comparing measurements in intact and defaunated sediment cores before and after the addition of A. marina in summer and fall 2011. Higher organic matter remineralization rates, shallower O2 penetration, and greater sediment-water solute fluxes were observed in summer, consistent with higher sediment community metabolic rates at a higher temperature. Lugworm activity stimulated porewater exchange (5.1 × in summer, 1.9 × in fall), organic matter remineralization (6.2 × in summer, 1.9 × in fall), aerobic respiration (2.4 × in summer, 2.1 × in fall), alkalinity release (4.7 × in summer, 4.0 × in fall), nutrient regeneration, and iron cycling. The effects of lugworm activity on net sediment-water fluxes were similar but more pronounced in summer than in fall. Alkalinity release in fall was entirely driven by metabolic carbonate dissolution, while this process explained between 22 and 69% of total alkalinity production in summer, indicating the importance of other processes in this season. By enhancing organic matter remineralization and the reoxidation of reduced metabolites by the sediment microbial community, lugworm activity stimulated the production of dissolved inorganic carbon and metabolic acidity, which in turn enhanced metabolic CaCO3 dissolution efficiency. In summer, evidence of microbial long distance electron transport (LDET) was observed in defaunated sediment. Thus, alkalinity production by net carbonate dissolution was likely supplemented by anaerobic respiration and LDET in summer. PMID:25431515

  1. Manipulation of the apoplastic pH of intact plants mimics stomatal and growth responses to water availability and microclimatic variation.

    PubMed

    Wilkinson, Sally; Davies, William J

    2008-01-01

    The apoplastic pH of intact Forsythiaxintermedia (cv. Lynwood) and tomato (Solanum lycopersicum) plants has been manipulated using buffered foliar sprays, and thereby stomatal conductance (g(s)), leaf growth rate, and plant water loss have been controlled. The more alkaline the pH of the foliar spray, the lower the g(s) and/or leaf growth rate subsequently measured. The most alkaline pH that was applied corresponds to that measured in sap extracted from shoots of tomato and Forsythia plants experiencing, respectively, soil drying or a relatively high photon flux density (PFD), vapour pressure deficit (VPD), and temperature in the leaf microclimate. The negative correlation between PFD/VPD/temperature and g(s) determined in well-watered Forsythia plants exposed to a naturally varying summer microclimate was eliminated by spraying the plants with relatively alkaline but not acidic buffers, providing evidence for a novel pH-based signalling mechanism linking the aerial microclimate with stomatal aperture. Increasing the pH of the foliar spray only reduced g(s) in plants of the abscisic acid (ABA)-deficient flacca mutant of tomato when ABA was simultaneously sprayed onto leaves or injected into stems. In well-watered Forsythia plants exposed to a naturally varying summer microclimate (variable PFD, VPD, and temperature), xylem pH and leaf ABA concentration fluctuated but were positively correlated. Manipulation of foliar apoplastic pH also affected the response of g(s) and leaf growth to ABA injected into stems of intact Forsythia plants. The techniques used here to control physiology and water use in intact growing plants could easily be applied in a horticultural context.

  2. Effects of sodium hypochlorite and high pH buffer solution in electrokinetic soil treatment on soil chromium removal and the functional diversity of soil microbial community.

    PubMed

    Cang, Long; Zhou, Dong-Mei; Alshawabkeh, Akram N; Chen, Hai-Feng

    2007-04-02

    Effects of sodium hypochlorite (NaClO), applied as an oxidant in catholyte, and high pH buffer solution on soil Cr removal and the functional diversity of soil microbial community during enhanced electrokinetic treatments of a chromium (Cr) contaminated red soil are evaluated. Using pH control system to maintain high alkalinity of soil together with the use of NaClO increased the electrical conductivities of soil pore liquid and electroosmotic flux compared with the control (Exp-01). The pH control and NaClO improved the removal of Cr(VI) and total Cr from the soil. The highest removal percentages of soil Cr(VI) and total Cr were 96 and 72%, respectively, in Exp-04 when the pH value of the anolyte was controlled at 10 and NaClO was added in the catholyte. The alkaline soil environment and introduction of NaClO in the soil enhanced the desorption of Cr(VI) from the soil and promoted Cr(III) oxidation to mobile Cr(VI), respectively. However, the elevated pH and introduction of NaClO in the soil, which are necessary for improving the removal efficiency of soil Cr, resulted in a significantly adverse impact on the functional diversity of soil microbial community. It suggests that to assess the negative impact of extreme conditions for enhancing the extraction efficiencies of Cr on the soil properties and function is necessary.

  3. Effect of alkaline-earth ions on the dynamics of alkali ions in bismuthate glasses

    NASA Astrophysics Data System (ADS)

    Dutta, A.; Ghosh, A.

    2005-12-01

    The effect of alkaline earth ions on the dynamics of Li+ ions in bismuthate glasses has been studied in the temperature range 353-503K and in the frequency range 10Hz-2MHz . The dc conductivity increases and activation energy decreases with the increase of a particular alkaline earth content for the glasses with a fixed alkali content. The increased modification of the network due to the increase in alkaline earth content in the compositions is responsible for the increasing conductivity. Also the compositions with smaller alkaline earth ions were found to exhibit higher conductivity. Although the conductivity increases with the decrease of ionic radii of alkaline earth ions, the activation energy shows a maximum for the Sr ion. The electric modulus and the conductivity formalisms have been employed to study the relaxation dynamics of charge carriers in these glasses. The alkali ions were observed to change their dynamics with the change of the alkaline earth ions. The same anomalous trend for activation energy for the conductivity relaxation frequency and the hopping frequency was also observed for glasses containing SrO. It was also observed that the mobile lithium ion concentrations are independent of nature of alkaline earth ions in these glasses.

  4. Temperature dependence of the absorbance of alkaline solutions of 4-nitrophenyl phosphate--a potential source of error in the measurement of alkaline phosphatase activity.

    PubMed

    Burtis, C A; Seibert, L E; Baird, M A; Sampson, E J

    1977-09-01

    The absorbance of an alkaline solution of 4-nitrophenyl phosphate is a function of temperature. Quantitative evaluation of this phenomenon indicates that it (a) depends on the concentration of the compound and is independent of source, buffer concentration, and pH above 9.0; (b) is reversible; (c) is not a result of alkaline hydrolysis or 4-nitrophenol contamination; and (d) correlates with a temperature-induced shift of its absorbance spectrum. The phenomenon may represent a potential analytical problem in methods for alkaline phosphatase in which this compound is the substrate. If thermal equilibrium is not reached and maintained during an alkaline phosphatase assay, the thermochromic response will be included in the measured rate. The magnitude of this error depends on the thermal response and control characteristics of each particular instrument and the reaction conditions under which such an analysis is performed.

  5. Critical factors in the design of cost-effective alkaline flooding

    SciTech Connect

    Lorenz, P.B.; Peru, D.A.

    1991-02-01

    A review of major alkaline flooding projects highlights the recognized fact that alkali consumption and scale formation are serious deterrents when strong alkalis are used. The review also confirms that there are several mechanisms of oil mobilization besides reducing interfacial tension. Even oils of low acid number may be amenable to alkaline flooding. Moreover, alkalis in a lower pH range - which have minimal reaction with reservoir minerals - can often mobilize oil, especially when enhanced with a low concentration of surfactant. However, the future of alkaline flooding depends critically on improved reservoir analysis, which includes factors that have often been neglected: (1) thorough mineralogical analysis; (2) evaluation of ion-exchange properties; and (3) assessment of carbon dioxide content. An evaluation of high-pH alkaline flooding field tests over the past 60 years shows that the majority of tests did not produce encouraging results. Laboratory and limited field experience with lower pH alkalis suggests that they may be more feasible in selected cases. Alkaline flooding should be rejected if there is as much as 1% gypsum in the rock or as much as 1 mol % CO{sub 2} in the fluid. Otherwise, a flood at moderate pH (around 10) can be considered for low-kaolinite reservoirs. For low-montmorillonite reservoirs with less than 5 meq divalent exchange ions per kg of rock, a very low pH (around 8.5) may be effective when enhanced with surfactant. 55 refs., 3 tabs.

  6. Metal bioavailability and toxicity to fish in low-alkalinity lakes - a critical-review

    USGS Publications Warehouse

    Spry, D.J.; Wiener, J.G.

    1991-01-01

    Fish in low-alkalinity lakes having ph of 6.0-6.5 Or less often have higher body or tissue burdens of mercury, cadmium, and lead than do fish in nearby lakes with higher ph. The greater bioaccumulation of these metals in such waters seems to result partly from the greater aqueous abundances of biologically available forms (ch3hg+, cd2+, and pb2+) at low ph. In addition, the low concentrations of aqueous calcium in low-alkalinity lakes increase the permeability of biological membranes to these metals, which in fish may cause greater uptake from both water and food. Fish exposed to aqueous inorganic aluminum in the laboratory and field accumulate the metal in and on the epithelial cells of the gills; however, there is little accumulation of aluminum in the blood or internal organs. In low-ph water, both sublethal and lethal toxicity of aluminum has been clearly demonstrated in both laboratory and field studies at environmental concentrations. In contrast, recently measured aqueous concentrations of total mercury, methylmercury, cadmium, and lead in low-alkalinity lakes are much lower than the aqueous concentrations known to cause acute or chronic toxicity in fish, although the vast majority of toxicological research has involved waters with much higher ionic strength than that in low-alkalinity lakes. Additional work with fish is needed to better assess (1) the toxicity of aqueous metals in low-alkalinity waters, and (2) the toxicological significance of dietary methylmercury and cadmium.

  7. Zinc electrode in alkaline electrolyte

    SciTech Connect

    McBreen, J.

    1995-12-31

    The zinc electrode in alkaline electrolyte is unusual in that supersaturated zincate solutions can form during discharge and spongy or mossy zinc deposits can form on charge at low overvoltages. The effect of additives on regular pasted ZnO electrodes and calcium zincate electrodes is discussed. The paper also reports on in situ x-ray absorption (XAS) results on mossy zinc deposits.

  8. Bioenergetics and the Role of Soluble Cytochromes c for Alkaline Adaptation in Gram-Negative Alkaliphilic Pseudomonas

    PubMed Central

    Matsuno, T.; Yumoto, I.

    2015-01-01

    Very few studies have been conducted on alkaline adaptation of Gram-negative alkaliphiles. The reversed difference of H+ concentration across the membrane will make energy production considerably difficult for Gram-negative as well as Gram-positive bacteria. Cells of the alkaliphilic Gram-negative bacterium Pseudomonas alcaliphila AL15-21T grown at pH 10 under low-aeration intensity have a soluble cytochrome c content that is 3.6-fold higher than that of the cells grown at pH 7 under high-aeration intensity. Cytochrome c-552 content was higher (64% in all soluble cytochromes c) than those of cytochrome c-554 and cytochrome c-551. In the cytochrome c-552-dificient mutant grown at pH 10 under low-aeration intensity showed a marked decrease in μmax⁡ [h−1] (40%) and maximum cell turbidity (25%) relative to those of the wild type. Considering the high electron-retaining abilities of the three soluble cytochromes c, the deteriorations in the growth of the cytochrome c-552-deficient mutant could be caused by the soluble cytochromes c acting as electron storages in the periplasmic space of the bacterium. These electron-retaining cytochromes c may play a role as electron and H+ condenser, which facilitate terminal oxidation at high pH under air-limited conditions, which is difficult to respire owing to less oxygen and less H+. PMID:25705691

  9. [Effect of calcium on medium alkalinization induced by salicylic acid in Salvia miltiorrhiza suspension cultures].

    PubMed

    Liu, Liancheng; Wang, Cong; Dong, Juan'e; Su, Hui; Zhuo, Zequn; Xue, Yaxin

    2013-07-01

    We studied medium alkalinization in Salvia miltiorrhiza suspension cultures treated with salicylic acid and the effect of Ca2+ in this process through application of calcium channel antagonists (Verapamil, LaCl3, LiCl, 2-APB) and ionophore A23187. The results show that salicylic acid could induce significant medium alkalinization in S. miltiorrhiza culture. Verapamil and LaCl3 or LiCl and 2-APB, two different groups of calcium channel antagonist, significantly inhibited the medium alkalinization induced by salicylic acid. However, the suppression effect of verapamil or LaCl3 on medium alkalinization induced by salicylic acid was higher than that of LiCl or 2-APB. When two types of calcium channel inhibitor (LaCl3 and 2-APB) were used together, the medium alkalinization induced by salicylic acid was completely suppressed and even reduced the pH in medium. On the other hand, A23187 could promote the medium alkalinization. Based on the results above, we speculated that salicylic acid could induce significant medium alkalinization in S. miltiorrhiza culture, depending on the calcium from both extracell and intracell. Moreover, calcium from extracell plays a more dominant role in this process. Reveal of relationship in this research between Ca2+ and medium alkalinization can provide theory evidence for mechanism of the plant secondary metabolism.

  10. Release of bound procyanidins from cranberry pomace by alkaline hydrolysis.

    PubMed

    White, Brittany L; Howard, Luke R; Prior, Ronald L

    2010-07-14

    Procyanidins in plant products are present as extractable or unextractable/bound forms. We optimized alkaline hydrolysis conditions to liberate procyanidins and depolymerize polymers from dried cranberry pomace. Alkaline extracts were neutralized (pH 6-7) and then procyanidins were extracted with ethyl acetate and analyzed by normal phase high performance liquid chromatography. Alkaline hydrolysis resulted in an increase in low molecular weight procyanidins, and the increase was greater at higher temperature, short time combinations. The most procyanidins (DP1-DP3) were extracted at 60 degrees C for 15 min with each concentration of NaOH. When compared to conventional extraction using homogenization with acetone/water/acetic acid (70:29.5:0.5 v/v/v), treatment with NaOH increased procyanidin oligomer extraction by 3.8-14.9-fold, with the greatest increase being DP1 (14.9x) and A-type DP2 (8.4x) procyanidins. Alkaline treatment of the residue remaining after conventional extraction resulted in further procyanidin extraction, indicating that procyanidins are not fully extracted by conventional extraction methods.

  11. Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

    2005-12-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or reservoirs with different sand lenses with high permeability contrast. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more crude oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or reservoirs with high permeability contrast zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction with different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium-polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in

  12. Alkaline stress and iron deficiency regulate iron uptake and riboflavin synthesis gene expression differently in root and leaf tissue: implications for iron deficiency chlorosis.

    PubMed

    Hsieh, En-Jung; Waters, Brian M

    2016-10-01

    Iron (Fe) is an essential mineral that has low solubility in alkaline soils, where its deficiency results in chlorosis. Whether low Fe supply and alkaline pH stress are equivalent is unclear, as they have not been treated as separate variables in molecular physiological studies. Additionally, molecular responses to these stresses have not been studied in leaf and root tissues simultaneously. We tested how plants with the Strategy I Fe uptake system respond to Fe deficiency at mildly acidic and alkaline pH by measuring root ferric chelate reductase (FCR) activity and expression of selected Fe uptake genes and riboflavin synthesis genes. Alkaline pH increased cucumber (Cucumis sativus L.) root FCR activity at full Fe supply, but alkaline stress abolished FCR response to low Fe supply. Alkaline pH or low Fe supply resulted in increased expression of Fe uptake genes, but riboflavin synthesis genes responded to Fe deficiency but not alkalinity. Iron deficiency increased expression of some common genes in roots and leaves, but alkaline stress blocked up-regulation of these genes in Fe-deficient leaves. In roots of the melon (Cucumis melo L.) fefe mutant, in which Fe uptake responses are blocked upstream of Fe uptake genes, alkaline stress or Fe deficiency up-regulation of certain Fe uptake and riboflavin synthesis genes was inhibited, indicating a central role for the FeFe protein. These results suggest a model implicating shoot-to-root signaling of Fe status to induce Fe uptake gene expression in roots.

  13. A Constructed Alkaline Consortium and Its Dynamics in Treating Alkaline Black Liquor with Very High Pollution Load

    PubMed Central

    Yang, Chunyu; Cao, Guangchun; Li, Yang; Zhang, Xiaojun; Ren, Hongyan; Wang, Xia; Feng, Jinhui; Zhao, Liping; Xu, Ping

    2008-01-01

    Background Paper pulp wastewater resulting from alkaline extraction of wheat straw, known as black liquor, is very difficult to be treated and causes serious environmental problems due to its high pH value and chemical oxygen demand (COD) pollution load. Lignin, semicellulose and cellulose are the main contributors to the high COD values in black liquor. Very few microorganisms can survive in such harsh environments of the alkaline wheat straw black liquor. A naturally developed microbial community was found accidentally in a black liquor storing pool in a paper pulp mill of China. The community was effective in pH decreasing, color and COD removing from the high alkaline and high COD black liquor. Findings Thirty-eight strains of bacteria were isolated from the black liquor storing pool, and were grouped as eleven operational taxonomy units (OTUs) using random amplified polymorphic DNA-PCR profiles (RAPD). Eleven representative strains of each OTU, which were identified as genera of Halomonas and Bacillus, were used to construct a consortium to treat black liquor with a high pH value of 11.0 and very high COD pollution load of 142,600 mg l−1. After treatment by the constructed consortium, about 35.4% of color and 39,000 mg l−1 (27.3%) CODcr were removed and the pH decreased to 7.8. 16S rRNA gene polymerase chain reaction denaturant gradient gel electrophoresis (PCR-DGGE) and gas chromatography/mass spectrometry (GC/MS) analysis suggested a two-stage treatment mechanism to elucidate the interspecies collaboration: Halomonas isolates were important in the first stage to produce organic acids that contributed to the pH decline, while Bacillus isolates were involved in the degradation of lignin derivatives in the second stage under lower pH conditions. Conclusions/Significance Tolerance to the high alkaline environment and good controllability of the simple consortium suggested that the constructed consortium has good potential for black liquor treatment

  14. Influence of binding pH and protein solubility on the dynamic binding capacity in hydrophobic interaction chromatography.

    PubMed

    Baumann, Pascal; Baumgartner, Kai; Hubbuch, Jürgen

    2015-05-29

    Hydrophobic interaction chromatography (HIC) is one of the most frequently used purification methods in biopharmaceutical industry. A major drawback of HIC, however, is the rather low dynamic binding capacity (DBC) obtained when compared to e.g. ion exchange chromatography (IEX). The typical purification procedure for HIC includes binding at neutral pH, independently of the proteins nature and isoelectric point. Most approaches to process intensification are based on resin and salt screenings. In this paper a combination of protein solubility data and varying binding pH leads to a clear enhancement of dynamic binding capacity. This is shown for three proteins of acidic, neutral, and alkaline isoelectric points. High-throughput solubility screenings as well as miniaturized and parallelized breakthrough curves on Media Scout RoboColumns (Atoll, Germany) were conducted at pH 3-10 on a fully automated robotic workstation. The screening results show a correlation between the DBC and the operational pH, the protein's isoelectric point and the overall solubility. Also, an inverse relationship of DBC in HIC and the binding kinetics was observed. By changing the operational pH, the DBC could be increased up to 30% compared to the standard purification procedure performed at neutral pH. As structural changes of the protein are reported during HIC processes, the applied samples and the elution fractions were proven not to be irreversibly unfolded.

  15. Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation.

    PubMed

    Kitadai, Norio

    2017-03-01

    Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg(2+)) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu(2+)) are therefore not beneficial places for peptide bond formation on the primitive

  16. Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation

    NASA Astrophysics Data System (ADS)

    Kitadai, Norio

    2017-03-01

    Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg2+) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu2+) are therefore not beneficial places for peptide bond formation on the primitive

  17. COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson

    2004-10-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A prior fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Neither aluminum citrate-polyacrylamide nor silicate-polyacrylamide gel systems produced significant incremental oil in linear corefloods. Both flowing and rigid flowing chromium acetate-polyacrylamide gels produced incremental oil with the rigid flowing gel producing the greatest amount. Higher oil recovery could have been due to higher differential pressures across cores. None of the gels tested

  18. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, David B.; Lao, Guifang

    1998-01-01

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium.

  19. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, D.B.; Lao, G.

    1998-01-06

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium. 3 figs.

  20. Alkaline fermentation of waste sludge causes a significant reduction of antibiotic resistance genes in anaerobic reactors.

    PubMed

    Huang, Haining; Zheng, Xiong; Chen, Yinguang; Liu, Hui; Wan, Rui; Su, Yinglong

    2017-02-15

    Alkaline fermentation has been reported to be an effective method to recover valuable products from waste sludge. However, to date, the potential effect of alkaline pH on the fate of antibiotic resistance genes (ARGs) during anaerobic fermentation of sludge has never been documented. In this study, the target ARGs in sludge was observed to be removed effectively and stably when sludge was anaerobically fermented at pH10. Compared with the control (without pH adjustment), the abundances of target ARGs at pH10 were reduced by 0.87 (sulI), 1.36 (sulII), 0.42 (tet(O)), 1.11 (tet(Q)), 0.79 (tet(C)) and 1.04 (tet(X)) log units. Further investigations revealed that alkaline fermentation shifted the community structures of potential ARGs hosts. Moreover, alkaline fermentation remarkably decreased the quantities and the ARGs-possessing ability of genetic vectors (plasmid DNA, extracellular DNA and phage DNA), which might limit the transfer of ARGs via conjugation, transformation and transduction. These results suggest that the shifted compositions of gene hosts and restricted gene transfer potential might be the critical reasons for the attenuation of ARGs at pH10.

  1. Remediation of Former Manufactured Gas Plant Tars Using Alkaline Flushing

    NASA Astrophysics Data System (ADS)

    Hauswirth, S.; Rylander, S.; Birak, P. S.; Miller, C. T.

    2010-12-01

    The remediation of former manufactured gas plant (FMGP) tars in the subsurface is particularly difficult due to the wetting behavior and high viscosities of these dense non-aqueous liquids (DNAPLs). Alkaline flooding is a technique which has proven effective in improving the recovery of crude oils, which share some characteristics with FMGP tars. For this study, we measured the effect of NaOH solutions on interfacial tension and conducted column experiments to investigate the feasibility of applying this technique to FMGP tars. The pendant drop technique was used to measure interfacial tensions for solutions ranging from 0-1% NaOH. Column experiments were conducted by contaminating sands with tars recovered from a FMGP then flushing the columns with NaOH solutions. A final, 70% v/v ethanol cosolvent flush was conducted to investigate the effectiveness of a two-stage remediation approach. The mass removal of tar, as well as 26 individual PAHs, was measured, along with the aqueous phase mass flux of PAHs after each flushing stage. The interfacial tension was reduced from about 20 mN/m with pure water to a minimum of 0.05 mN/m at a concentration of 0.1% NaOH. In the column experiments, alkaline flushing resulted in a 50% reduction of the residual saturation. Aqueous phase PAH concentrations, however, were similar before and after the alkaline flushing stage. The combination of alkaline and cosolvent flushing resulted in an overall reduction of 95% of the total mass of the 16 EPA PAHs. Final aqueous phase concentrations were reduced significantly for lower molecular weight PAHs, but increased slightly for the higher molecular weight compounds, likely due to their increased mole fraction within the remaining tar. Additional work is being conducted to improve the effectiveness of the alkaline flushing through the use of surfactants and polymers.

  2. Molecular Basis of pH and Ca2+ Regulation of Aquaporin Water Permeability

    PubMed Central

    Németh-Cahalan, Karin L.; Kalman, Katalin; Hall, James E.

    2004-01-01

    Aquaporins facilitate the diffusion of water across cell membranes. We previously showed that acid pH or low Ca2+ increase the water permeability of bovine AQP0 expressed in Xenopus oocytes. We now show that external histidines in loops A and C mediate the pH dependence. Furthermore, the position of histidines in different members of the aquaporin family can “tune” the pH sensitivity toward alkaline or acid pH ranges. In bovine AQP0, replacement of His40 in loop A by Cys, while keeping His122 in loop C, shifted the pH sensitivity from acid to alkaline. In the killifish AQP0 homologue, MIPfun, with His at position 39 in loop A, alkaline rather than acid pH increased water permeability. Moving His39 to His40 in MIPfun, to mimic bovine AQP0 loop A, shifted the pH sensitivity back to the acid range. pH regulation was also found in two other members of the aquaporin family. Alkaline pH increased the water permeability of AQP4 that contains His at position 129 in loop C. Acid and alkaline pH sensitivity was induced in AQP1 by adding histidines 48 (in loop A) and 130 (in loop C). We conclude that external histidines in loops A and C that span the outer vestibule contribute to pH sensitivity. In addition, we show that when AQP0 (bovine or killifish) and a crippled calmodulin mutant were coexpressed, Ca2+ sensitivity was lost but pH sensitivity was maintained. These results demonstrate that Ca2+ and pH modulation are separable and arise from processes on opposite sides of the membrane. PMID:15078916

  3. Biological impacts of enhanced alkalinity in Carcinus maenas.

    PubMed

    Cripps, Gemma; Widdicombe, Stephen; Spicer, John I; Findlay, Helen S

    2013-06-15

    Further steps are needed to establish feasible alleviation strategies that are able to reduce the impacts of ocean acidification, whilst ensuring minimal biological side-effects in the process. Whilst there is a growing body of literature on the biological impacts of many other carbon dioxide reduction techniques, seemingly little is known about enhanced alkalinity. For this reason, we investigated the potential physiological impacts of using chemical sequestration as an alleviation strategy. In a controlled experiment, Carcinus maenas were acutely exposed to concentrations of Ca(OH)2 that would be required to reverse the decline in ocean surface pH and return it to pre-industrial levels. Acute exposure significantly affected all individuals' acid-base balance resulting in slight respiratory alkalosis and hyperkalemia, which was strongest in mature females. Although the trigger for both of these responses is currently unclear, this study has shown that alkalinity addition does alter acid-base balance in this comparatively robust crustacean species.

  4. Cellular chloride and bicarbonate retention alters intracellular pH regulation in Cftr KO crypt epithelium

    PubMed Central

    Walker, Nancy M.; Liu, Jinghua; Stein, Sydney R.; Stefanski, Casey D.; Strubberg, Ashlee M.

    2015-01-01

    Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR), an anion channel providing a major pathway for Cl− and HCO3− efflux across the apical membrane of the epithelium. In the intestine, CF manifests as obstructive syndromes, dysbiosis, inflammation, and an increased risk for gastrointestinal cancer. Cftr knockout (KO) mice recapitulate CF intestinal disease, including intestinal hyperproliferation. Previous studies using Cftr KO intestinal organoids (enteroids) indicate that crypt epithelium maintains an alkaline intracellular pH (pHi). We hypothesized that Cftr has a cell-autonomous role in downregulating pHi that is incompletely compensated by acid-base regulation in its absence. Here, 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein microfluorimetry of enteroids showed that Cftr KO crypt epithelium sustains an alkaline pHi and resistance to cell acidification relative to wild-type. Quantitative real-time PCR revealed that Cftr KO enteroids exhibit downregulated transcription of base (HCO3−)-loading proteins and upregulation of the basolateral membrane HCO3−-unloader anion exchanger 2 (Ae2). Although Cftr KO crypt epithelium had increased Ae2 expression and Ae2-mediated Cl−/HCO3− exchange with maximized gradients, it also had increased intracellular Cl− concentration relative to wild-type. Pharmacological reduction of intracellular Cl− concentration in Cftr KO crypt epithelium normalized pHi, which was largely Ae2-dependent. We conclude that Cftr KO crypt epithelium maintains an alkaline pHi as a consequence of losing both Cl− and HCO3− efflux, which impairs pHi regulation by Ae2. Retention of Cl− and an alkaline pHi in crypt epithelium may alter several cellular processes in the proliferative compartment of Cftr KO intestine. PMID:26542396

  5. Cellular chloride and bicarbonate retention alters intracellular pH regulation in Cftr KO crypt epithelium.

    PubMed

    Walker, Nancy M; Liu, Jinghua; Stein, Sydney R; Stefanski, Casey D; Strubberg, Ashlee M; Clarke, Lane L

    2016-01-15

    Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR), an anion channel providing a major pathway for Cl(-) and HCO3 (-) efflux across the apical membrane of the epithelium. In the intestine, CF manifests as obstructive syndromes, dysbiosis, inflammation, and an increased risk for gastrointestinal cancer. Cftr knockout (KO) mice recapitulate CF intestinal disease, including intestinal hyperproliferation. Previous studies using Cftr KO intestinal organoids (enteroids) indicate that crypt epithelium maintains an alkaline intracellular pH (pHi). We hypothesized that Cftr has a cell-autonomous role in downregulating pHi that is incompletely compensated by acid-base regulation in its absence. Here, 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein microfluorimetry of enteroids showed that Cftr KO crypt epithelium sustains an alkaline pHi and resistance to cell acidification relative to wild-type. Quantitative real-time PCR revealed that Cftr KO enteroids exhibit downregulated transcription of base (HCO3 (-))-loading proteins and upregulation of the basolateral membrane HCO3 (-)-unloader anion exchanger 2 (Ae2). Although Cftr KO crypt epithelium had increased Ae2 expression and Ae2-mediated Cl(-)/HCO3 (-) exchange with maximized gradients, it also had increased intracellular Cl(-) concentration relative to wild-type. Pharmacological reduction of intracellular Cl(-) concentration in Cftr KO crypt epithelium normalized pHi, which was largely Ae2-dependent. We conclude that Cftr KO crypt epithelium maintains an alkaline pHi as a consequence of losing both Cl(-) and HCO3 (-) efflux, which impairs pHi regulation by Ae2. Retention of Cl(-) and an alkaline pHi in crypt epithelium may alter several cellular processes in the proliferative compartment of Cftr KO intestine.

  6. Interrelationship between growth factor-induced pH changes and intracellular Ca/sup 2 +/

    SciTech Connect

    Ives, H.E.; Daniel, T.O.

    1987-04-01

    Many mitogens cause rapid changes in intracellular pH and Ca/sup 2 +/. The authors studied the patterns of pH and Ca/sup 2 +/ changes after exposure of murine fibroblasts to platelet-derived growth factor (PDGF), bombesin, phorbol 12-myristate 13-acetate (PMA), and the vasoactive peptide bradykinin. Intracellular pH and Ca/sup 2 +/ were measured by using the fluorescent dyes 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein and fura-2. Three distinct patterns of intracellular pH change were observed. (i) PDGF and bombesin caused a rapid cytoplasmic acidification of 0.03 pH unit followed by a slower alkalinization of approx. = 0.11 pH unit above the resting pH of 6.88. (ii) PMA caused alkalinization without causing the early acidification. (iii) Bradykinin caused rapid acidification without the slower net alkalinization. All acidification responses were amiloride resistant. Patterns of intracellular Ca/sup 2 +/ response were also determined for each agent. In Ca/sup 2 +/-buffered cells, PDGF, bombesin, bradykinin, and ionomycin failed to induce cellular acidification, but alkalinization responses to PDGF, bombesin, and PMA persisted. They propose that the transient acidification seen with PDGF, bombesin, and other agents is the result of increased intracellular Ca/sup 2 +/. However, growth factor-induced alkalinization via the Na/sup +//H/sup +/ exchanger is independent of changes in Ca/sup 2 +/.

  7. Ethanol production from glycerol-containing biodiesel waste by Klebsiella variicola shows maximum productivity under alkaline conditions.

    PubMed

    Suzuki, Toshihiro; Nishikawa, Chiaki; Seta, Kohei; Shigeno, Toshiya; Nakajima-Kambe, Toshiaki

    2014-05-25

    Biodiesel fuel (BDF) waste contains large amounts of crude glycerol as a by-product, and has a high alkaline pH. With regard to microbial conversion of ethanol from BDF-derived glycerol, bacteria that can produce ethanol at alkaline pH have not been reported to date. Isolation of bacteria that shows maximum productivity under alkaline conditions is essential to effective production of ethanol from BDF-derived glycerol. In this study, we isolated the Klebsiella variicola TB-83 strain, which demonstrated maximum ethanol productivity at alkaline pH. Strain TB-83 showed effective usage of crude glycerol with maximum ethanol production at pH 8.0-9.0, and the culture pH was finally neutralized by formate, a by-product. In addition, the ethanol productivity of strain TB-83 under various culture conditions was investigated. Ethanol production was more efficient with the addition of yeast extract. Strain TB-83 produced 9.8 g/L ethanol (0.86 mol/mol glycerol) from cooking oil-derived BDF waste. Ethanol production from cooking oil-derived BDF waste was higher than that of new frying oil-derived BDF and pure-glycerol. This is the first report to demonstrate that the K. variicola strain TB-83 has the ability to produce ethanol from glycerol at alkaline pH.

  8. Development of alkaline fuel cells.

    SciTech Connect

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari; Horan, James L.; Caire, Benjamin R.; Ziegler, Zachary C.; Herring, Andrew M.; Yang, Yuan; Zuo, Xiaobing; Robson, Michael H.; Artyushkova, Kateryna; Patterson, Wendy; Atanassov, Plamen Borissov

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassovs research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herrings group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  9. Acidic pH increases airway surface liquid viscosity in cystic fibrosis

    PubMed Central

    Tang, Xiao Xiao; Ostedgaard, Lynda S.; Hoegger, Mark J.; Moninger, Thomas O.; Karp, Philip H.; McMenimen, James D.; Choudhury, Biswa; Varki, Ajit; Stoltz, David A.; Welsh, Michael J.

    2016-01-01

    Cystic fibrosis (CF) disrupts respiratory host defenses, allowing bacterial infection, inflammation, and mucus accumulation to progressively destroy the lungs. Our previous studies revealed that mucus with abnormal behavior impaired mucociliary transport in newborn CF piglets prior to the onset of secondary manifestations. To further investigate mucus abnormalities, here we studied airway surface liquid (ASL) collected from newborn piglets and ASL on cultured airway epithelia. Fluorescence recovery after photobleaching revealed that the viscosity of CF ASL was increased relative to that of non-CF ASL. CF ASL had a reduced pH, which was necessary and sufficient for genotype-dependent viscosity differences. The increased viscosity of CF ASL was not explained by pH-independent changes in HCO3– concentration, altered glycosylation, additional pH-induced disulfide bond formation, increased percentage of nonvolatile material, or increased sulfation. Treating acidic ASL with hypertonic saline or heparin largely reversed the increased viscosity, suggesting that acidic pH influences mucin electrostatic interactions. These findings link loss of cystic fibrosis transmembrane conductance regulator–dependent alkalinization to abnormal CF ASL. In addition, we found that increasing Ca2+ concentrations elevated ASL viscosity, in part, independently of pH. The results suggest that increasing pH, reducing Ca2+ concentration, and/or altering electrostatic interactions in ASL might benefit early CF. PMID:26808501

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

    PubMed Central

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

    2008-01-01

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

  11. Acidic pH increases airway surface liquid viscosity in cystic fibrosis.

    PubMed

    Tang, Xiao Xiao; Ostedgaard, Lynda S; Hoegger, Mark J; Moninger, Thomas O; Karp, Philip H; McMenimen, James D; Choudhury, Biswa; Varki, Ajit; Stoltz, David A; Welsh, Michael J

    2016-03-01

    Cystic fibrosis (CF) disrupts respiratory host defenses, allowing bacterial infection, inflammation, and mucus accumulation to progressively destroy the lungs. Our previous studies revealed that mucus with abnormal behavior impaired mucociliary transport in newborn CF piglets prior to the onset of secondary manifestations. To further investigate mucus abnormalities, here we studied airway surface liquid (ASL) collected from newborn piglets and ASL on cultured airway epithelia. Fluorescence recovery after photobleaching revealed that the viscosity of CF ASL was increased relative to that of non-CF ASL. CF ASL had a reduced pH, which was necessary and sufficient for genotype-dependent viscosity differences. The increased viscosity of CF ASL was not explained by pH-independent changes in HCO3- concentration, altered glycosylation, additional pH-induced disulfide bond formation, increased percentage of nonvolatile material, or increased sulfation. Treating acidic ASL with hypertonic saline or heparin largely reversed the increased viscosity, suggesting that acidic pH influences mucin electrostatic interactions. These findings link loss of cystic fibrosis transmembrane conductance regulator-dependent alkalinization to abnormal CF ASL. In addition, we found that increasing Ca2+ concentrations elevated ASL viscosity, in part, independently of pH. The results suggest that increasing pH, reducing Ca2+ concentration, and/or altering electrostatic interactions in ASL might benefit early CF.

  12. Metabolic microenvironmental control by photosynthetic biofilms under changing macroenvironmental temperature and pH conditions.

    PubMed

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

    2008-10-01

    Ex situ microelectrode experiments, using cyanobacterial biofilms from karst water creeks, were conducted under various pH, temperature, and constant-alkalinity conditions to investigate the effects of changing environmental parameters on cyanobacterial photosynthesis-induced calcification. Microenvironmental chemical conditions around calcifying sites were controlled by metabolic activity over a wide range of photosynthesis and respiration rates, with little influence from overlying water conditions. Regardless of overlying water pH levels (from 7.8 to 8.9), pH at the biofilm surface was approximately 9.4 in the light and 7.8 in the dark. The same trend was observed at various temperatures (4 degrees C and 17 degrees C). Biological processes control the calcium carbonate saturation state (Omega) in these and similar systems and are able to maintain Omega at approximately constant levels over relatively wide environmental fluctuations. Temperature did, however, have an effect on calcification rate. Calcium flux in this system is limited by its diffusion coefficient, resulting in a higher calcium flux (calcification and dissolution) at higher temperatures, despite the constant, biologically mediated pH. The ability of biological systems to mitigate the effects of environmental perturbation is an important factor that must be considered when attempting to predict the effects of increased atmospheric partial CO(2) pressure on processes such as calcification and in interpreting microfossils in the fossil record.

  13. Alkaline-fermented foods: a review with emphasis on pidan fermentation.

    PubMed

    Wang, J; Fung, D Y

    1996-01-01

    Alkaline-fermented foods constitute a group of less-known food products that are widely consumed in Southeast Asia and African countries. They can be made from different raw ingredients. For instance, Japanese natto, Thai thua-nao, and kinema are made from cooked soybeans, dawadawa from African locust beans, ogiri from melon seeds, ugba from African oil beans, kawal from fresh legale leaves, owoh from cotton seeds, and pidan from fresh poultry eggs. In alkaline-fermented foods, the protein of the raw materials is broken down into amino acids and peptides; ammonia is released during the fermentation, raising the pH of the final products and giving the food a strong ammoniacal smell. Most alkaline fermentations are achieved spontaneously by mixed bacteria cultures, principally dominated by Bacillus subtilis. In other cases, pure cultures can be used. For example, Japanese natto is inoculated with a pure culture of B. subtilis var natto. Pidan is a special example of alkaline fermentation. Instead of using microorganisms, pidan is made using an alkali-treated fermentation. Sodium hydroxide (NaOH) is produced from the reaction of sodium carbonate (Na2CO3), water (H2O), and calcium oxide (CaO) of pickle or coating mud. NaOH penetrates into the eggs, causing the physicochemical changes, color changes, and gelation. The appearance of pidan differs from fresh eggs in that the white becomes a semitransparent tea-brown color, and the yolk is solid or semisolid with a dark-green color. The nutritional value of pidan is slightly decreased compared with fresh eggs, but pidan has an extremely long shelf life and a pleasant, fragrant taste that is preferred by most people in Southeast Asian countries. In a small-scale laboratory study conducted by the authors, B. subtilis was not found in pidan. Four Staphylococcus spp. (S. cohnii, S. epidermidis, S. haemolyticus, and S. warneri) and two strains of Bacillus spp. (B. cereus and B. macerans) were isolated from pidan. Staphylococcus

  14. Bioavailability and dissipation of anthracene from soil with different alkalinity and salinity.

    PubMed

    Castro-Silva, Carolina; Ruiz-Valdiviezo, Víctor Manuel; Rivas-Rivera, Sandra Gabriela; Sosa-Trinidad, Alma Rosa; Luna-Guido, Marco; Delgado-Balbuena, Laura; Marsch, Rodolfo; Dendooven, Luc

    2015-01-01

    Bioavailability of contaminants, such as anthracene (Anthra), a polycyclic aromatic hydrocarbon (PAHs), and their removal from soil has been related to their extractability with non-exhaustive techniques, such as hydroxypropyl-beta-cyclodextrin (HPCD) or n-butanol. Anthra was extracted with HPCD, n-butanol and by exhaustive ultrasonic extraction method from sterilized and unsterilized alkaline soil of the former lake Texcoco, having pH ranging from pH 8.2 to 10.1 and electrolytic conductivity varying from 1.2 dS m(-1) to 95.2 dS m(-1), respectively. About 24.4 and 37.6% of Anthra was removed biologically from soil as estimated by exhaustive technique after 56 days. The percentage of Anthra that was removed from soil by exhaustive technique was not related to the amount thatwas extractable with HPCD or n-butanol. It was found that the Anthra extractable with n-butanol or HPCD did not correlate well with the removal of the contaminant from soil. In this study, the removal of Anthra from soil could not be predicted by the amount of Anthra that was extracted with n-butanol or HPCD .

  15. Influence of calcium and silica on hydraulic properties of sodium montmorillonite assemblages under alkaline conditions.

    PubMed

    Kinsela, Andrew S; Tjitradjaja, Alice; Collins, Richard N; Waite, T David; Payne, Timothy E; Macdonald, Bennett C T; White, Ian

    2010-03-01

    A sodium-washed montmorillonite was exposed to calcium and silica under alkaline conditions in order to gain insight into possible interactions of engineered clay barriers and cementitious leachates found in many waste storage facilities. The changes in physico-chemical properties of the material were investigated using a combination of dead-end filtration, electrophoresis and scanning electron microscopy. The results show minimal differentiation between unaltered Na-montmorillonite samples at the two pH values tested (9 and 12), with the structure of the resulting assemblages arising from repulsive tactoid interactions. The addition of calcium (50 mM) greatly decreases the size of the structural network, and in doing so, increases the hydraulic conductivity approximately 65-fold, with the effect being greatest at pH 12. Whilst the addition of silica alone (10 mM) produced little change in the hydraulic properties of montmorillonite, its combined effect with calcium produced alterations to the structural assemblages that could not be accounted for by the presence of calcium alone. The likely binding of calcium with multiple silanol groups appears to enhance the retention of water within the Na-montmorillonite assemblage, whilst still allowing the fluent passage of water. The results confirm that polyvalent cations such as Ca(2+) may have a dramatic effect on the structural and hydraulic properties of montmorillonite assemblages while the effects of solutions containing both silicate and calcium are complex and influenced by silica-cation interactions.

  16. Development of an alkaline fuel cell subsystem

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A two task program was initiated to develop advanced fuel cell components which could be assembled into an alkaline power section for the Space Station Prototype (SSP) fuel cell subsystem. The first task was to establish a preliminary SSP power section design to be representative of the 200 cell Space Station power section. The second task was to conduct tooling and fabrication trials and fabrication of selected cell stack components. A lightweight, reliable cell stack design suitable for the SSP regenerative fuel cell power plant was completed. The design meets NASA's preliminary requirements for future multikilowatt Space Station missions. Cell stack component fabrication and tooling trials demonstrated cell components of the SSP stack design of the 1.0 sq ft area can be manufactured using techniques and methods previously evaluated and developed.

  17. Oxygen electrodes for rechargeable alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Swette, Larry; Giner, Jose

    1987-09-01

    Electrocatalysts and supports for the positive electrode of moderate temperature single unit rechargeable alkaline fuel cells were investigated and developed. The electrocatalysts are defined as the material with a higher activity for the oxygen electrode reaction than the support. Advanced development will require that the materials be prepared in high surface area forms, and may also entail integration of various candidate materials. Eight candidate support materials and seven electrocatalysts were investigated. Of the 8 support, 3 materials meet the preliminary requirements in terms of electrical conductivity and stability. Emphasis is now on preparing in high surface area form and testing under more severe corrosion stress conditions. Of the 7 electrocatalysts prepared and evaluated, at least 5 materials remain as potential candidates. The major emphasis remains on preparation, physical characterization and electrochemical performance testing.

  18. Development of an alkaline fuel cell subsystem

    NASA Astrophysics Data System (ADS)

    1987-03-01

    A two task program was initiated to develop advanced fuel cell components which could be assembled into an alkaline power section for the Space Station Prototype (SSP) fuel cell subsystem. The first task was to establish a preliminary SSP power section design to be representative of the 200 cell Space Station power section. The second task was to conduct tooling and fabrication trials and fabrication of selected cell stack components. A lightweight, reliable cell stack design suitable for the SSP regenerative fuel cell power plant was completed. The design meets NASA's preliminary requirements for future multikilowatt Space Station missions. Cell stack component fabrication and tooling trials demonstrated cell components of the SSP stack design of the 1.0 sq ft area can be manufactured using techniques and methods previously evaluated and developed.

  19. Oxygen electrodes for rechargeable alkaline fuel cells

    NASA Technical Reports Server (NTRS)

    Swette, Larry; Giner, Jose

    1987-01-01

    Electrocatalysts and supports for the positive electrode of moderate temperature single unit rechargeable alkaline fuel cells were investigated and developed. The electrocatalysts are defined as the material with a higher activity for the oxygen electrode reaction than the support. Advanced development will require that the materials be prepared in high surface area forms, and may also entail integration of various candidate materials. Eight candidate support materials and seven electrocatalysts were investigated. Of the 8 support, 3 materials meet the preliminary requirements in terms of electrical conductivity and stability. Emphasis is now on preparing in high surface area form and testing under more severe corrosion stress conditions. Of the 7 electrocatalysts prepared and evaluated, at least 5 materials remain as potential candidates. The major emphasis remains on preparation, physical characterization and electrochemical performance testing.

  20. [DNA degradation during standard alkaline of thermal denaturation].

    PubMed

    Drozhdeniuk, A P; Sulimova, G E; Vaniushin, B F

    1976-01-01

    Essential degradation 8 DNA (up to 10 per cent) with liberation of acid-soluble fragments takes place on the standard alkaline (0,01 M sodium phosphate, pH 12, 60 degrees, 15 min) or thermal (0.06 M sodium phosphate buffer, pH 6.8, 102 degrees C, 15 min) denaturation. This degradation is more or less selective: fraction of low molecular weight fragments, isolated by hydroxyapatite cromatography and eluted by 0.06 M sodium phosphate buffer, pH 6.8 is rich in adenine and thymine and contains about 2 times less 5-methylcytosine than the total wheat germ DNA. The degree of degradation of DNA on thermal denaturation is higher than on alkaline degradation. Therefore while studying reassociation of various DNA, one and the same standard method of DNA denaturation should be used. Besides, both the level of DNA degradation and the nature of the resulting products (fragments) should be taken into account.

  1. Dephosphorylation of purine mononucleotides by alkaline phosphatases. Substrate specificity and inhibition patterns.

    PubMed

    Jensen, M H

    1979-11-09

    Three purine mononucleotides, adenosine-, inosine- and guanosine monophosphate, were used as substrates at pH 7.4 and at 10.4 for three alkaline phosphatases (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.1) containing similar phosphate-binding serine groups at their esteratic sites. Substrate specificity was found for the enzymes from calf intestine and bovine liver. Alkaline phosphatase from Escherichia coli was nonspecific. A substrate-dependent and pronounced inhibition with the purine analogue 1,3-dimethyl xanthine was found for the enzymes from intestine and liver, but not for alkaline phosphatase from E. coli. A substrate-independent and pronounced inhibition was found for all three enzymes with the phosphomonoester p-nitrophenol phosphate as the inhibitor. Alkaline phosphatases may play an important role in the regulation of the intracellular content of purine mononucleotides.

  2. The Martian ocean: First acid, then alkaline

    NASA Technical Reports Server (NTRS)

    Schaefer, M. W.

    1992-01-01

    In Mars' distant past, carbon dioxide and water may have been plentiful. Values of total outgassed CO2 from several to about 10 bar are consistent with present knowledge, and this amount of CO2 implies an amount of water outgassed equal to an equivalent depth of 500 to 1000 m. It is quite reasonable, therefore, to envision an early Mars in which there was a body or bodies of liquid water, perhaps in the northern plains, and a dense carbon dioxide atmosphere. Under such conditions, the pH of the water will be low, due to the dissolution of carbon dioxide in the water to form carbonic acid. This acidic water is capable of weathering the available rock quite intensely, particularly because this rock is likely to be heavily fractured (from meteorite bombardment) or even consist of fine particles (such as pyroclastic deposits). As time goes on, however, the carbon dioxide atmosphere will rapidly pass through the ocean to form carbonate deposits. As the density of the atmosphere decreases, so will the flux of carbonic acid into the ocean. Without this input of carbonic acid, the effect of the dissolved weathering products will be to increase the pH of the water. The ocean will then become alkaline. To study this process, I have developed a geochemical cycle model for the atmosphere-hydrosphere-regolith system of Mars. The treatment of geochemical cycles as complex kinetic chemical reactions has been undertaken for terrestrial systems in recent years with much success. This method is capable of elegantly handling the interactions between the simultaneous chemical reactions needed to understand such a system.

  3. Intracellular pH and the Control of Multidrug Resistance

    NASA Astrophysics Data System (ADS)

    Simon, Sanford; Roy, Deborshi; Schindler, Melvin

    1994-02-01

    Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, the distribution of two drugs, doxorubicin and daunomycin, was monitored in fibroblasts and myeloma cells. In both cell types the drugs rapidly accumulated within the cells. The highest concentrations were measured in the most acidic compartments-e.g., lysosomes. Modifying the cellular pH in drug-sensitive cells to mimic reported shifts in MDR caused an immediate change in the cellular drug concentration. Drug accumulation was enhanced by acidic shifts and reversed by alkaline shifts. All of these effects were rapid and reversible. These results demonstrate that the alkaline shift observed in MDR is sufficient to prevent the accumulation of chemotherapeutic drugs independent of active drug efflux.

  4. Intracellular pH and the control of multidrug resistance.

    PubMed Central

    Simon, S; Roy, D; Schindler, M

    1994-01-01

    Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, the distribution of two drugs, doxorubicin and daunomycin, was monitored in fibroblasts and myeloma cells. In both cell types the drugs rapidly accumulated within the cells. The highest concentrations were measured in the most acidic compartments--e.g., lysosomes. Modifying the cellular pH in drug-sensitive cells to mimic reported shifts in MDR caused an immediate change in the cellular drug concentration. Drug accumulation was enhanced by acidic shifts and reversed by alkaline shifts. All of these effects were rapid and reversible. These results demonstrate that the alkaline shift observed in MDR is sufficient to prevent the accumulation of chemotherapeutic drugs independent of active drug efflux. Images PMID:8302842

  5. The Added Value of a PhD in Medicine--PhD Students' Perceptions of Acquired Competences

    ERIC Educational Resources Information Center

    Anttila, Henrika; Lindblom-Ylänne, Sari; Lonka, Kristi; Pyhältö, Kirsi

    2015-01-01

    PhD in the field of medicine is more common than in any other domain. Many medical doctors are driven towards PhD, but also students with other backgrounds (usually MSc) are conducting a PhD in medical schools. Higher education has invested a lot in developing generic and research competences. Still little is known about how PhD students…

  6. Proteomic analysis of protein expression in Lactobacillus plantarum in response to alkaline stress.

    PubMed

    Lee, KiBeom; Rho, Beom-Seop; Pi, KyungBae; Kim, Ho-Jin; Choi, Yun-Jaie

    2011-04-20

    Lactobacillus plantarum, a probiotic organism that plays an important role in the microbial fermentation of alkaline materials in fermenting foods, faces alkaline stress during the fermentation process. Here, we report the patterns of protein expression in L. plantarum subjected to transient (1h) alkaline stress at pH 7.7, 8.7 or 9.7. Thirty-three alkaline-responsive proteins were identified by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS). Identification of proteins showing differential expression in response to alkaline stress revealed that the alkaline stress response of L. plantarum is a complex process. Some proteins appear to be induced, others repressed. These proteins could be clustered into nine groups based on their probable functions: energy metabolism, transport system, purine/pyrimidine metabolism, amino acid metabolism, proteolytic activity, transcription-translation, stress-related, general function, and unknown functions. These proteomic analyses are expected to prove useful in understanding the adaptive response of L. plantarum strains to alkaline stress and may facilitate future investigations into the genetic and physiological aspects of this response.

  7. Permeability Modification Using a Reactive Alkaline-Soluble Biopolymer

    SciTech Connect

    Snadra L. Fox; X. Xie; K. D. Schaller; E. P. Robertson; G. A. Bala

    2003-10-01

    Polymer injection has been used in reservoirs to alleviate contrasting permeability zones. Current technology relies on the use of cross-linking agents to initiate gelation. The use of biological polymers are advantageous in that they can block high permeability areas, are environmentally friendly, and have potential to form reversible gels without the use of hazardous cross-linkers. Recent efforts at the Idaho National Engineering and Environmental Laboratory (INEEL) have produced a reactive alkaline-soluble biopolymer from Agrobacterium sp. ATCC no. 31749 that gels upon decreasing the pH of the polymeric solution. The focus of this study was to determine the impact an alkaline-soluble biopolymer can have on sandstone permeability. Permeability modification was investigated by injecting solubilized biopolymer into Berea sandstone cores and defining the contribution of pH, salt, temperature, and Schuricht crude oil on biopolymer gelation. The biopolymer was soluble in KOH at a pH greater than 11.4 and gelled when the pH dropped below 10.8. The Berea sandstone core buffered the biopolymer solution, decreasing the pH sufficiently to form a gel, which subsequently decreased the permeability. The effluent pH of the control cores injected with 0.01 {und M} KOH (pH 12.0) and 0.10{und M} KOH (pH 13.0) decreased to 10.6 and 12.7, respectively. The permeability of the sandstone core injected with biopolymer was decreased to greater than 95% of the original permeability at 25 C in the presence of 2% NaCl, and Schuricht crude oil; however, the permeability increased when the temperature of the core was increased to 60 C. Residual resistance factors as high as 792 were seen in Berea cores treated with biopolymer. The buffering capacity of sandstone has been demonstrated to reduce the pH of a biopolymer solution sufficiently to cause the polymer to form a stable in-situ gel. This finding could potentially lead to alternate technology for permeability modification, thus

  8. COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; David Stewart; Bill Jones

    2005-04-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A prior fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent

  9. Connexin 43 hemichannels mediate the Ca2+ influx induced by extracellular alkalinization

    PubMed Central

    Sánchez, Helmuth A.; Lee, Sung C.; Altenberg, Guillermo A.; Nathanson, Michael H.; Sáez, Juan C.

    2010-01-01

    Although alkaline pH is known to trigger Ca2+ influx in diverse cells, no pH-sensitive Ca2+ channel has been identified. Here, we report that extracellular alkalinization induces opening of connexin 43 hemichannels (Cx43 HCs). Increasing extracellular pH from 7.4 to 8.5, in the presence of physiological Ca2+/Mg2+ concentrations, rapidly increased the ethidium uptake rate and open probability of HCs in Cx43 and Cx43EGFP HeLa transfectants (HeLa-Cx3 and HeLa-Cx43EGFP, respectively) but not in parental HeLa cells (HeLa-parental) lacking Cx43 HCs. The increase in ethidium uptake induced by pH 8.5 was not affected by raising the extracellular Ca2+ concentration from 1.8 to 10 mM but was inhibited by a connexin HC inhibitor (La3+). Probenecid, a pannexin HC blocker, had no effect. Extracellular alkalinization increased the intracellular Ca2+ levels only in cells expressing HCs. The above changes induced by extracellular alkalinization did not change the cellular distribution of Cx43, suggesting that HC activation occurs through a gating mechanism. Experiments on cells expressing a COOH-terminal truncated Cx43 mutant indicated that the effects of alkalinization on intracellular Ca2+ and ethidium uptake did not depend on the Cx43 C terminus. Moreover, purified dephosphorylated Cx43 HCs reconstituted in liposomes were Ca2+ permeable, suggesting that Ca2+ influx through Cx43 HCs could account for the elevation in intracellular Ca2+ elicited by extracellular alkalinization. These studies identify a membrane pathway for Ca2+ influx and provide a potential explanation for the activation of cellular events induced by extracellular alkalinization. PMID:20881238

  10. Effect of pH on floc properties and membrane fouling in coagulation - ultrafiltration process with ferric chloride and polyferric chloride.

    PubMed

    Dong, Hongyu; Gao, Baoyu; Yue, Qinyan; Wang, Yan; Li, Qian

    2015-07-01

    Impact of pH on coagulation-ultrafiltration (C-UF) process was investigated with respect to coagulation efficiency, floc characteristics and membrane fouling in this study. Ferric chloride (FeCl3) and polyferric chloride with basicity of 1.0 and 2.2 (denoted as PFC10 and PFC22) were used as coagulants and Fe (III) species in them was measured by a timed complexation spectroscopy method. Floc properties under four pH conditions were evaluated using a laser diffraction particle sizing device. Ultrafiltration experiments were conducted by a dead-end batch unit. The results showed that organic matter removal efficiency was higher under acidic conditions than under other pH conditions and turbidity removal efficiency was higher under alkaline condition. At same pH, FeCl3 containing higher monomeric and polymeric species (Fea and Feb) had better organic matter removal and higher turbidity removal efficiency was obtained by coagulants with larger percentage of polymer or colloidal species (Fec). Flocs formed under acidic ranges were larger, weaker and looser. At pH 4.0, 7.0 and 9.0, flocs by FeCl3 were larger and weaker than these by PFC10, followed by PFC22. In case of FeCl3 and PFC10, acidic pH conditions were helpful to reduce membrane fouling. For PFC22, permeate fluxes were less sensitive to pH variations.

  11. Alkalinization in the Isolated and Perfused Anterior Midgut of the Larval Mosquito, Aedes aegypti

    PubMed Central

    Onken, Horst; Moffett, Stacia B.; Moffett, David F.

    2008-01-01

    In the present study, isolated midguts of larval Aedes aegypti L. (Diptera: Culicidae) were mounted on perfusion pipettes and bathed in high buffer mosquito saline. With low buffer perfusion saline, containing m-cresol purple, transepithelial voltage was monitored and luminal alkalinization became visible through color changes of m-cresol purple after perfusion stop. Lumen negative voltage and alkalinization depended on metabolic energy and were stimulated in the presence of serotonin (0.2 µmol l-1). In some experiments a pH microelectrode in the lumen recorded pH values up to 10 within minutes after perfusion stop. The V-ATPase inhibitor concanamycin (50 µmol l-1) on the hemolymph side almost abolished Vte and inhibited luminal alkalinization. The carbonic anhydrase inhibitor, methazolamide (50 µmol l-1), on either the luminal or hemolymph-side, or the inhibitor of anion transport, DIDS (1 mmol l-1) on the luminal side, had no effect on Vte or alkalinization. Cl- substitution in the lumen or on both sides of the tissue affected Vte, but the color change of m-cresol purple was unchanged from control conditions. Hemolymph-side Na+ substitution or addition of the Na+/H+ exchange inhibitor, amiloride (200 µmol l-1), reduced Vte and luminal alkalinization. Luminal amiloride (200 µmol l-1) was without effects on Vte or alkalinization. High K+ (60 mmol l-1) in the lumen reduced Vte without affecting alkalinization. These results indicate that strong luminal alkalinization in isolated and perfused anterior midgut of larval A. aegypti depends on basolateral V-ATPase, but is apparently independent of carbonic anhydrase, apical Cl-/HCO3- exchange or apical K+/2H+ antiport. PMID:20307229

  12. Studies on alkaline serine protease produced by Bacillus clausii GMBE 22.

    PubMed

    Kazan, Dilek; Bal, Hulya; Denizci, Aziz Akin; Ozturk, Nurcin Celik; Ozturk, Hasan Umit; Dilgimen, Aydan Salman; Ozturk, Dilek Coskuner; Erarslan, Altan

    2009-01-01

    An alkali tolerant Bacillus strain having extracellular serine alkaline protease activity was newly isolated from compost and identified as Bacillus clausii GMBE 22. An alkaline protease (AP22) was 4.66-fold purified in 51.5% yield from Bacillus clausii GMBE 22 by ethanol precipitation and DEAE-cellulose anion exchange chromatography. The purified enzyme was identified as serine protease by LC-ESI-MS analysis. Its complete inhibition by phenylmethanesulfonylfluoride (PMSF) also justified that it is a serine alkaline protease. The molecular weight of the enzyme is 25.4 kDa. Optimal temperature and pH values are 60 degrees C and 12.0, respectively. The enzyme showed highest specificity to N-Suc-Ala-Ala-Pro-Phe-pNA. The K(m) and k(cat) values for hydrolysis of this substrate are 0.347 mM and 1141 min(-1) respectively. The enzyme was affected by surface active agents to varying extents. The enzyme is stable for 2 h at 30 degrees C and pH 10.5. AP22 is also stable for 5 days over the pH range 9.0-11.0 at room temperature. AP22 has good pH stability compared with the alkaline proteases belonging to other strains of Bacillus clausii reported in the literature.

  13. Long-term evolution of highly alkaline steel slag drainage waters.

    PubMed

    Riley, Alex L; Mayes, William M

    2015-07-01

    The disposal of slag generated by the steel industry can have negative consequences upon the surrounding aquatic environment by the generation of high pH waters, leaching of potentially problematic trace metals, and rapid rates of calcite precipitation which smother benthic habitats. A 36-year dataset was collated from the long-term ambient monitoring of physicochemical parameters and elemental concentrations of samples from two steel slag leachate-affected watercourses in northern England. Waters were typified by elevated pH (>10), high alkalinity, and were rich in dissolved metals (e.g. calcium (Ca), aluminium (Al), and zinc (Zn)). Long-term trend analysis was performed upon pH, alkalinity, and Ca concentration which, in addition to Ca flux calculations, were used to highlight the longevity of pollution arising as a result of the dumping and subsequent leaching of steel slags. Declines in calcium and alkalinity have been modest over the monitoring period and not accompanied by significant declines in water pH. If the monotonic trends of decline in alkalinity and calcium continue in the largest of the receiving streams, it will be in the region of 50-80 years before calcite precipitation would be expected to be close to baseline levels, where ecological impacts would be negligible.

  14. Recovery of phosphorus and nitrogen from alkaline hydrolysis supernatant of excess sludge by magnesium ammonium phosphate.

    PubMed

    Bi, Wei; Li, Yiyong; Hu, Yongyou

    2014-08-01

    Magnesium ammonium phosphate (MAP) method was used to recover orthophosphate (PO₄(3-)-P) and ammonium nitrogen (NH4(+)-N) from the alkaline hydrolysis supernatant of excess sludge. To reduce alkali consumption and decrease the pH of the supernatant, two-stage alkaline hydrolysis process (TSAHP) was designed. The results showed that the release efficiencies of PO₄(3-)-P and NH₄(+)-N were 41.96% and 7.78%, respectively, and the pH of the supernatant was below 10.5 under the running conditions with initial pH of 13, volume ratio (sludge dosage/water dosage) of 1.75 in second-stage alkaline hydrolysis reactor, 20 g/L of sludge concentration in first-stage alkaline hydrolysis reactor. The order of parameters influencing MAP reaction was analyzed and the optimized conditions of MAP reaction were predicted through the response surface methodology. The recovery rates of PO₄(3-)-P and NH₄(+)-N were 46.88% and 16.54%, respectively under the optimized conditions of Mg/P of 1.8, pH 9.7 and reaction time of 15 min.

  15. An alkaline approach to treating cooling towers for control of Legionella pneumophila.

    PubMed Central

    States, S J; Conley, L F; Towner, S G; Wolford, R S; Stephenson, T E; McNamara, A M; Wadowsky, R M; Yee, R B

    1987-01-01

    Earlier field and laboratory studies have shown that Legionella species survive and multiply in the pH range 5.5 to 9.2. Additionally, the technical feasibility of operating cooling towers at elevated alkalinities and pH has previously been documented by published guidelines. The guidelines indicate that these conditions facilitate corrosion control and favor chlorine persistence which enhances the effectiveness of continuous chlorination in biofouling control. This information suggests that control of Legionella species in cooling towers can be accomplished by operating the towers under alkaline conditions. To test this possibility, we collected water samples over a period of months from a hospital cooling tower. The samples were analyzed for a variety of chemical parameters. Subsamples were pasteurized and inoculated with non-agar-passaged Legionella pneumophila which had been maintained in tap water. Correlation of subsequent Legionella growth with corresponding pH and alkalinity values revealed statistically significant inverse associations. These data support the hypothesis that operating cooling towers outside of the optimal conditions for Legionella growth (e.g., at elevated alkalinities and a pH greater than 9) may be a useful approach to controlling growth in this habitat. PMID:3662515

  16. Bactericidal activity of alkaline salts of fatty acids towards bacteria associated with poultry processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antibacterial activity of alkaline salts of caproic, caprylic, capric, lauric, and myristic acids were determined using the agar diffusion assay. A 0.5M concentration of each fatty acid (FA) was dissolved in 1.0 M potassium hydroxide (KOH), and pH of the mixtures was adjusted to 10.5 with citric aci...

  17. Simulation of hydrogen sulphide absorption in alkaline solution using a packed column.

    PubMed

    Azizi, Mohamed; Biard, Pierre-François; Couvert, Annabelle; Ben Amor, Mohamed

    2014-01-01

    In this work, a simulation tool was developed for hydrogen sulphide (H₂S) removal in an alkaline solution in packed columns working at countercurrent. Modelling takes into account the mass-transfer enhancement due to the reversible reactions between H₂S and the alkaline species (CO(²⁻)(3), HCO⁻(3), and HO⁻) in the liquid film. Many parameters can be controlled by the user such as the gas and liquid inlet H₂S concentrations, the gas and liquid flow rates, the scrubbing liquid pH, the desired H₂S removal efficiency, the temperature, the alkalinity, etc. Since the influence of the hydrodynamic and mass-transfer performances in a packed column is well known, the numerical resolutions performed were dedicated to the study of the influence of the chemical conditions (through the pH and the alkalinity), the temperature and the liquid-to-gas mass flow rate ratio (L/G). A packed column of 3 m equipped with a given random packing material working at countercurrent and steady state has been modelled. The results show that the H₂S removal efficiency increases with the L/G, the pH, the alkalinity and more surprisingly with the temperature. Alkalinity has a very significant effect on the removal efficiency through the mass-transfer enhancement and buffering effect, which limits pH decreasing due to H₂S absorption. This numerical resolution provides a tool for designers and researchers involved in H₂S treatment to understand deeper the process and optimize their processes.

  18. Coupling the Alkaline-Surfactant-Polymer Technology and the Gelation Technology to Maximize Oil Production

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

    2005-12-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or reservoirs with different sand lenses with high permeability contrast. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more crude oil than waterflooding froin swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or reservoirs with high permeability contrast zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction with different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium-polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in

  19. Diclofenac salts. III. Alkaline and earth alkaline salts.

    PubMed

    Fini, Adamo; Fazio, Giuseppe; Rosetti, Francesca; Angeles Holgado, M; Iruín, Ana; Alvarez-Fuentes, Josefa

    2005-11-01

    Diclofenac salts containing the alkaline and two earth alkaline cations have been prepared and characterized by scanning electron microscopy (SEM) and EDAX spectroscopy; and by thermal and thermogravimetric analysis (TGA): all of them crystallize as hydrate when precipitated from water. The salts dehydrate at room temperature and more easily on heating, but recovery the hydration, when placed in a humid environment. X-ray diffraction spectra suggest that on dehydration new peaks appear on diffractograms and the lattice of the salts partially looses crystallinity. This phenomenon is readily visible in the case of the calcium and magnesium salts, whose thermograms display a crystallization exotherm, before melting or decomposing at temperatures near or above 200 degrees C; these last salts appear to form solvates, when prepared from methanol. The thermogram of each salt shows a complex endotherm of dehydration about 100 degrees C; the calcium salt displays two endotherms, well separated at about 120 and 160 degrees C, which disappear after prolonged heating. Decomposition exotherms, before or soon after the melting, appear below 300 degrees C. The ammonium salt is thermally unstable and, when heated to start dehydration, dissociates and leaves acidic diclofenac.

  20. Molecular Components of the Neurospora crassa pH Signaling Pathway and Their Regulation by pH and the PAC-3 Transcription Factor

    PubMed Central

    Virgilio, Stela; Cupertino, Fernanda Barbosa; Bernardes, Natália Elisa; Freitas, Fernanda Zanolli; Takeda, Agnes Alessandra Sekijima; Fontes, Marcos Roberto de Mattos; Bertolini, Maria Célia

    2016-01-01

    Environmental pH induces a stress response triggering a signaling pathway whose components have been identified and characterized in several fungi. Neurospora crassa shares all six components of the Aspergillus nidulans pH signaling pathway, and we investigate here their regulation during an alkaline pH stress response. We show that the N. crassa pal mutant strains, with the exception of Δpal-9, which is the A. nidulans palI homolog, exhibit low conidiation and are unable to grow at alkaline pH. Moreover, they accumulate the pigment melanin, most likely via regulation of the tyrosinase gene by the pH signaling components. The PAC-3 transcription factor binds to the tyrosinase promoter and negatively regulates its gene expression. PAC-3 also binds to all pal gene promoters, regulating their expression at normal growth pH and/or alkaline pH, which indicates a feedback regulation of PAC-3 in the pal gene expression. In addition, PAC-3 binds to the pac-3 promoter only at alkaline pH, most likely influencing the pac-3 expression at this pH suggesting that the activation of PAC-3 in N. crassa results from proteolytic processing and gene expression regulation by the pH signaling components. In N. crassa, PAC-3 is proteolytically processed in a single cleavage step predominately at alkaline pH; however, low levels of the processed protein can be observed at normal growth pH. We also demonstrate that PAC-3 preferentially localizes in the nucleus at alkaline pH stress and that the translocation may require the N. crassa importin-α since the PAC-3 nuclear localization signal (NLS) has a strong in vitro affinity with importin-α. The data presented here show that the pH signaling pathway in N. crassa shares all the components with the A. nidulans and S. cerevisiae pathways; however, it exhibits some properties not previously described in either organism. PMID:27557053

  1. Molecular Components of the Neurospora crassa pH Signaling Pathway and Their Regulation by pH and the PAC-3 Transcription Factor.

    PubMed

    Virgilio, Stela; Cupertino, Fernanda Barbosa; Bernardes, Natália Elisa; Freitas, Fernanda Zanolli; Takeda, Agnes Alessandra Sekijima; Fontes, Marcos Roberto de Mattos; Bertolini, Maria Célia

    2016-01-01

    Environmental pH induces a stress response triggering a signaling pathway whose components have been identified and characterized in several fungi. Neurospora crassa shares all six components of the Aspergillus nidulans pH signaling pathway, and we investigate here their regulation during an alkaline pH stress response. We show that the N. crassa pal mutant strains, with the exception of Δpal-9, which is the A. nidulans palI homolog, exhibit low conidiation and are unable to grow at alkaline pH. Moreover, they accumulate the pigment melanin, most likely via regulation of the tyrosinase gene by the pH signaling components. The PAC-3 transcription factor binds to the tyrosinase promoter and negatively regulates its gene expression. PAC-3 also binds to all pal gene promoters, regulating their expression at normal growth pH and/or alkaline pH, which indicates a feedback regulation of PAC-3 in the pal gene expression. In addition, PAC-3 binds to the pac-3 promoter only at alkaline pH, most likely influencing the pac-3 expression at this pH suggesting that the activation of PAC-3 in N. crassa results from proteolytic processing and gene expression regulation by the pH signaling components. In N. crassa, PAC-3 is proteolytically processed in a single cleavage step predominately at alkaline pH; however, low levels of the processed protein can be observed at normal growth pH. We also demonstrate that PAC-3 preferentially localizes in the nucleus at alkaline pH stress and that the translocation may require the N. crassa importin-α since the PAC-3 nuclear localization signal (NLS) has a strong in vitro affinity with importin-α. The data presented here show that the pH signaling pathway in N. crassa shares all the components with the A. nidulans and S. cerevisiae pathways; however, it exhibits some properties not previously described in either organism.

  2. Structural Insight into and Mutational Analysis of Family 11 Xylanases: Implications for Mechanisms of Higher pH Catalytic Adaptation

    PubMed Central

    Bai, Wenqin; Zhou, Cheng; Zhao, Yueju; Wang, Qinhong; Ma, Yanhe

    2015-01-01

    To understand the molecular basis of higher pH catalytic adaptation of family 11 xylanases, we compared the structures of alkaline, neutral, and acidic active xylanases and analyzed mutants of xylanase Xyn11A-LC from alkalophilic Bacillus sp. SN5. It was revealed that alkaline active xylanases have increased charged residue content, an increased ratio of negatively to positively charged residues, and decreased Ser, Thr, and Tyr residue content relative to non-alkaline active counterparts. Between strands β6 and β7, alkaline xylanases substitute an α-helix for a coil or turn found in their non-alkaline counterparts. Compared with non-alkaline xylanases, alkaline active enzymes have an inserted stretch of seven amino acids rich in charged residues, which may be beneficial for xylanase function in alkaline conditions. Positively charged residues on the molecular surface and ionic bonds may play important roles in higher pH catalytic adaptation of family 11 xylanases. By structure comparison, sequence alignment and mutational analysis, six amino acids (Glu16, Trp18, Asn44, Leu46, Arg48, and Ser187, numbering based on Xyn11A-LC) adjacent to the acid/base catalyst were found to be responsible for xylanase function in higher pH conditions. Our results will contribute to understanding the molecular mechanisms of higher pH catalytic adaptation in family 11 xylanases and engineering xylanases to suit industrial applications. PMID:26161643

  3. Combination of Successive Alkalinity Producing System (SAPS) and Aeration for Passive Treatment of Highly Acidic Mine Drainage

    NASA Astrophysics Data System (ADS)

    Oh, C.; Ji, S.

    2015-12-01

    Passive treatment system has been widely used for remediation of mine drainage since its advantage of low installation and maintenance cost. The system, however, has also a disadvantage in assuring remediation and management efficiency if the drainage is highly acidic mine drainage. To remediate acid mine drainage (AMD) especially showing high acidity, passive treatment system which consists of successive alkalinity producing system (SAPS) and subsequent aeration pond was proposed and its mechanisms and efficiency was evaluated in this research. Target AMD was obtained from Waryong coal mine and showed typical characteristics of AMD having high metal concentration and low pH (acidity > 300 mg/L as CaCO3). Four experimental cases were conducted; untreated, treated with SAPS, treated with aeration, treated with SAPS and aeration to compare role and mechanism of each unit. Between organic matter and limestone layer which constitute SAPS, the former eliminated most of Fe(III) and Al in the AMD so that the latter was kept from being clogged by precipitates. Net acidity of the AMD rapidly decreased by supplement of alkalinity at the limestone layer. A primary function of SAPS, producing alkalinity constantly without clogging, was attained due to addition a portion of limestone particle into the organic matter layer. The discharge from SAPS had low ORP and DO values because of an anaerobic environment formed at the organic matter layer although its alkalinity was increased. This water quality was unfavorable for Fe(II) to be oxidized. Installation of aeration pond after SAPS, therefore, could be effective way of enhancing oxidation rate of Fe(II). Among the experimental cases, the combination of SAPS and aeration pond was only able to remediate the AMD. This concluded that to remediate highly acidic mine drainage with passive treatment system, three critical conditions were required; pre-precipitation of Fe(III) and Al at organic matter layer in SAPS, constant alkalinity

  4. Organelle pH in the Arabidopsis endomembrane system.

    PubMed

    Shen, Jinbo; Zeng, Yonglun; Zhuang, Xiaohong; Sun, Lei; Yao, Xiaoqiang; Pimpl, Peter; Jiang, Liwen

    2013-09-01

    The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by combining the improved-solubility feature of solubility-modified green fluorescent protein (GFP) (smGFP) with the pH-sensing capability of the pHluorins and codon optimized for expression in Arabidopsis. PEpHluorin (plant-solubility-modified ecliptic pHluorin) gradually loses fluorescence as pH is lowered with fluorescence vanishing at pH 6.2 and PRpHluorin (plant-solubility-modified ratiomatric pHluorin), a dual-excitation sensor, allowing for precise measurements. Compartment-specific sensors were generated by further fusing specific sorting signals to PEpHluorin and PRpHluorin. Our results show that the pH of cytosol and nucleus is similar (pH 7.3 and 7.2), while peroxisomes, mitochondrial matrix, and plastidial stroma have alkaline pH. Compartments of the secretory pathway reveal a gradual acidification, spanning from pH 7.1 in the endoplasmic reticulum (ER) to pH 5.2 in the vacuole. Surprisingly, pH in the trans-Golgi network (TGN) and multivesicular body (MVB) is, with pH 6.3 and 6.2, quite similar. The inhibition of vacuolar-type H(+)-ATPase (V-ATPase) with concanamycin A (ConcA) caused drastic increase in pH in TGN and vacuole. Overall, the PEpHluorin and PRpHluorin are excellent pH sensors for visualization and quantification of pH in vivo, respectively.

  5. Effect of pH on fecal recovery of energy derived from volatile fatty acids.

    PubMed

    Kien, C L; Liechty, E A

    1987-01-01

    We assessed the effect of pH on volatilization of short-chain fatty acids during lyophilization. Acetic, propionic, valeric, and butyric acids were added to a fecal homogenate in amounts sufficient to raise the energy density by 18-27%. Fecal homogenate samples were either acidified (pH 2.8-3.2), alkalinized (pH 7.9-8.7), or left unchanged (4.0-4.8) prior to lyophilization and subsequent bomb calorimetry. Alkalinizing the fecal samples prevented the 20% loss of energy derived from each of these volatile fatty acids observed in samples either acidified or without pH adjustment. These data suggest that in energy balance studies involving subjects with active colonic fermentation, fecal samples should be alkalinized prior to lyophilization and bomb calorimetry.

  6. Alkaline protease from Thermoactinomyces sp. RS1 mitigates industrial pollution.

    PubMed

    Verma, Amit; Ansari, Mohammad W; Anwar, Mohmmad S; Agrawal, Ruchi; Agrawal, Sanjeev

    2014-05-01

    Proteases have found a wide application in the several industrial processes, such as laundry detergents, protein recovery or solubilization, prion degradation, meat tenderizations, and in bating of hides and skins in leather industries. But the main hurdle in industrial application of proteases is their economical production on a large scale. The present investigation aimed to exploit the locally available inexpensive agricultural and household wastes for alkaline protease production using Thermoactinomyces sp. RS1 via solid-state fermentation (SSF) technique. The alkaline enzyme is potentially useful as an additive in commercial detergents to mitigate pollution load due to extensive use of caustic soda-based detergents. Thermoactinomyces sp. RS1 showed good protease production under SSF conditions of 55 °C, pH 9, and 50 % moisture content with potato peels as solid substrate. The presented findings revealed that crude alkaline protease produced by Thermoactinomyces sp. RS1 via SSF is of potential application in silver recovery from used X-ray films.

  7. Physiological aspects of alkaline phosphatase in selected cyanobacteria.

    PubMed

    Doonan, B B; Jensen, T E

    1980-01-01

    The alkaline phosphatase of Plectonema boryanum shows a considerable increase in activity following placement of the cells in a phosphate free medium. Five days of phosphate starvation result in a 14-fold increase of alkaline phosphatase activity. Growth in the presence of inhibitors of transcription and translation indicate that the synthesis of the enzyme is de novo. Orthophosphate causes an immediate inhibition of enzyme activity. Enzyme was extracted from P. boryanum with lysozyme or polymyxin B treatment in order to make comparative studies of cell bound and cell free enzyme. Of several enzyme specific inhibitors tested, mercuric chloride was the most effective. Temperature studies showed that the cell bound enzyme was most active at 40 degrees C while the cell free enzyme was most active at 70 degrees C. The pH optimum was 9 for the cell free enzyme, and 8.8 for the cell bound. The enzyme was tested to determine if it could hydrolyse a number of different organic compounds. It hydrolysed p-nitrophenol phosphate 100%, fructose-6-phosphate 45%, beta-glycerol phosphate 25% and other compounds to a lesser degree. Of seventeen other Cyanobacteria tested for alkaline phosphatase, all were positive, and of these eleven were inducible for the enzyme. Ten of the isolates released some of the enzyme into the culture medium. Michaelis constants for the enzyme were also determined.

  8. Effects of alkaline treatment for fibroblastic adhesion on titanium

    PubMed Central

    Cuellar-Flores, Miryam; Acosta-Torres, Laura Susana; Martínez-Alvarez, Omar; Sánchez-Trocino, Benjamin; de la Fuente-Hernández, Javier; Garcia-Garduño, Rigoberto; Garcia-Contreras, Rene

    2016-01-01

    Background: The surface energy of titanium (Ti) implants is very important when determining hydrophilicity or hydrophobicity, which is vital in osseointegration. The purpose of this study was to determine how Ti plates with an alkaline treatment (NaOH) affect the adhesion and proliferation of human periodontal ligament fibroblasts (HPLF). Materials and Methods: In vitro experimental study was carried out. Type 1 commercially pure Ti plates were analyzed with atomic force microscopy to evaluate surface roughness. The plates were treated ultrasonically with NaOH at 5 M (pH 13.7) for 45 s. HPLF previously established from periodontal tissue was inoculated on the treated Ti plates. The adhered and proliferated viable cell numbers were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method for 60 min and 24 h, respectively. The data were analyzed using Kruskal–Wallis tests and multiple comparisons of the Mann–Whitney U-test,P value was fixed at 0.05. Results: The mean roughness values equaled 0.04 μm with an almost flat surface and some grooves. The alkaline treatment of Ti plates caused significantly (P < 0.05) more pronounced HPLF adhesion and proliferation compared to untreated Ti plates. Conclusion: The treatment of Ti plates with NaOH enhances cell adhesion and the proliferation of HPLF cells. Clinically, the alkaline treatment of Ti-based implants could be an option to improve and accelerate osseointegration. PMID:28182066

  9. The Potential of Soft Soil Improvement Through a Coupled Technique Between Electro Kinetic and Alkaline Activation of Soft Soil

    NASA Astrophysics Data System (ADS)

    Ahmed, G. E.; Ismail, H. B.; Huat, B. K.; Afshin, A.; Azhar, A. T. S.

    2016-07-01

    Soil stabilization techniques have been in development for decades with different rates of success. Alkaline activation of soft soil is one of those techniques that has proved to deliver some of the best shear strength values with minor drawbacks in comparison with conventional soil stabilization methods. However, environmental considerations have not been taken into account, as major mineral glassy phase activators are poisoning alkaline solutions, such as sodium-, potassium-hydroxide, and sodium-, potassium-silicate, which poses serious hazards to man and environment. This paper addresses the ways of discarding the involvement of the aforementioned alkaline solutions in soft soil stabilization by investigating the potential of a coupled electro kinetic alkaline activation technique for soft soil strengthening, through which the provision of alkaline pH is governed by electro kinetic potential. Uncertainties in regard to the dissolution of aluminosilicate as well as the dominance of acidic front are challenges that need to be overcome.

  10. Alkaline detergent recycling via ultrafiltration

    SciTech Connect

    Steffani, C.; Meltzer, M.

    1995-06-01

    The metal finishing industry uses alkaline cleaners and detergents to remove oils and dirt from manufactured parts, often before they are painted or plated. The use of these cleaners has grown because environmental regulations are phasing out ozone depleting substances and placing restrictions on the use and disposal of many hazardous solvents. Lawrence Livermore National Laboratory is examining ultrafiltration as a cleaning approach that reclaims the cleaning solutions and minimizes wastes. The ultrafiltration membrane is made from sheets of polymerized organic film. The sheets are rolled onto a supporting frame and installed in a tube. Spent cleaning solution is pumped into a filter chamber and filtered through the membrane that captures oils and dirt and allows water and detergent to pass. The membrane is monitored and when pressure builds from oil and dirt, an automatic system cleans the surface to maintain solution flow and filtration quality. The results show that the ultrafiltration does not disturb the detergent concentration or alkalinity but removed almost all the oils and dirt leaving the solution in condition to be reused.

  11. Purification and characterization of Ulva pertusa Kjellm alkaline phosphatase.

    PubMed

    Yang, Dong; Wang, Jingyun; Bao, Yongming; An, Lijia

    2003-05-01

    The activity of alkaline phosphatase (ALP, EC 3.1.3.1.) was found in seaweeds, including five kinds of green alga, eighteen kinds of red alga, and six kinds of brown alga, collected from the seaside of Dalian in China. The enzyme was purified 1230-fold from Ulva pertusa Kjellm. It had a specific activity of 48.6 U/mg protein and was proven to be homogeneous by SDS-PAGE with a subunit molecular mass of 19.5 kDa. The activity of ALP peaked at pH9.8, and was completely inhibited by DTT and partly by NBS. The Michaelis-Menten constant Km and the maximum reaction velocity Vmax, at pH 9.8 and 37 degrees C were 0.950 mM and 5.00 microM/min, respectively.

  12. Relation of pH to toxicity of lampricide TFM in the laboratory

    USGS Publications Warehouse

    Bills, T.D.; Marking, L.L.; Howe, G.E.; Rach, J.J.

    1988-01-01

    In the control of larval sea lamprey (Petromyzon marinus ) with 3-trifluoromethyl-4-nitrophenol (TFM) in tributaries of the Great Lakes, occasional kills of other fishes have caused concern about the effects of the chemical on non-target organisms. Stream treatment rates have been based on previous application rates, alkalinity measurements, results of on-site toxicity tests, or combinations of these. Laboratory studies in 1987 showed that pH is the primary factor that affects the toxicity of TFM (the lower the pH, the greater the toxicity): even small changes in pH alter the toxicity, whereas substantial changes in alkalinity have little effect. In 12-h exposures, the 96-h LC50 for TFM to rainbow trout (Salmo gairdneri ) ranged from about 0.9 mg/L at pH 6.5 to > 100 mg/L at pH 9.5, but (at pH 7.5) the LC50's differed little at total alkalinities of about 18 mg/L and 207 mg/L. Decreases in pH as small as 0.5 pH unit caused nontoxic solutions to become toxic to rainbow trout. Some kills of non-target fish during stream treatments were reportedly caused by decreases in pH, and (conversely) that some stream treatments for sea lampreys were ineffective because pH increased.

  13. Phylogenetic analysis of the archaeal community in an alkaline-saline soil of the former lake Texcoco (Mexico).

    PubMed

    Valenzuela-Encinas, César; Neria-González, Isabel; Alcántara-Hernández, Rocio J; Enríquez-Aragón, J Arturo; Estrada-Alvarado, Isabel; Hernández-Rodríguez, César; Dendooven, Luc; Marsch, Rodolfo

    2008-03-01

    The soil of the former lake Texcoco is an extreme environment localized in the valley of Mexico City, Mexico. It is highly saline and alkaline, where Na+, Cl(-), HCO3(-) and CO3(2-) are the predominant ions, with a pH ranging from 9.8 to 11.7 and electrolytic conductivities in saturation extracts from 22 to 150 dS m(-1). Metagenomic DNA from the archaeal community was extracted directly from soil and used as template to amplify 16S ribosomal gene by PCR. PCR products were used to construct gene libraries. The ribosomal library showed that the archaeal diversity included Natronococcus sp., Natronolimnobius sp., Natronobacterium sp., Natrinema sp., Natronomonas sp., Halovivax sp., "Halalkalicoccus jeotgali" and novel clades within the family of Halobacteriaceae. Four clones could not be classified. It was found that the archaeal diversity in an alkaline-saline soil of the former lake Texcoco, Mexico, was low, but showed yet uncharacterized and unclassified species.

  14. Effects of applied potential on the stress corrosion cracking behavior of 7003 aluminum alloy in acid and alkaline chloride solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-yan; Song, Ren-guo; Sun, Bin; Lu, Hai; Wang, Chao

    2016-07-01

    Potentiodynamic polarization tests and slow strain rate test (SSRT) in combination with fracture morphology observations were conducted to investigate the stress corrosion cracking (SCC) behavior of 7003 aluminum alloy (AA7003) in acid and alkaline chloride solutions under various applied potentials ( E a). The results show that AA7003 is to a certain extent susceptible to SCC via anodic dissolution (AD) at open-circuit potential (OCP) and is highly susceptible to hydrogen embrittlement (HE) at high negative E a in the solutions with pH levels of 4 and 11. The susceptibility increases with negative shift in the potential when E a is less than -1000 mV vs. SCE. However, the susceptibility distinctly decreases because of the inhibition of AD when E a is equal to -1000 mV vs. SCE. In addition, the SCC susceptibility of AA7003 in the acid chloride solution is higher than that in the alkaline solution at each potential. Moreover, the effect of hydrogen on SCC increases with increasing hydrogen ion concentration.

  15. Separation of Alkaline Phosphatase Isoenzymes from Various Rat Tissues Using Flat-Bed Acrylamide Gel Isoelectric Focusing,

    DTIC Science & Technology

    1981-12-22

    Technical Bulletin No. 104. Alkaline phosphatase activity was expressed as 1 micromole of p- nitrophenol hydrolyzed per hour and specific alkaline... phosphatase activity was defined as the number of micromoles of p- nitrophenol hydrolyzed per hour per microgram of protein. The total protein was determined... phosphatase activity is known or suspected. Importantly, the procedure is easily adapted for acid phosphatase examination by merely changing the pH and

  16. The combined effect of temperature and pH on albite dissolution rate under far-from-equilibrium conditions

    NASA Astrophysics Data System (ADS)

    Gruber, Chen; Kutuzov, Ilya; Ganor, Jiwchar

    2016-08-01

    Two of the most studied aspects of albite dissolution kinetics are the effects of temperature and pH. Previous studies quantified the effect of pH on albite dissolution rate under constant temperature. These studies suggested that the effect of pH on dissolution rate can be attributed to three independent dissolution mechanisms that are dominant in different pH region: acidic - proton-promoted, neutral - water-promoted and alkaline - hydroxide-promoted. Based on experimental results, those studies developed a rate law to predict albite dissolution rate as a function of pH, assuming that the effect of pH is temperature independent. The effect of temperature was attributed either to the temperature dependency of the rate under constant pH or that of the rate law coefficients. Nevertheless no unified rate law that combines both effects was suggested. When applying the effects of temperature and pH assuming they are independent of each other in order to predict the dissolution rate at pH of about 5 and various temperatures, the predicted rate overestimate the rate by 0.5-1 order of magnitude. The current study develops and suggests the use of new rate law that is based on two fast adsorption reactions of protons and hydroxides on two different surface sites. The new rate law considers the effect of surface coverage of protons and hydroxides that is temperature dependent. The new rate law successfully describes the variation of albite dissolution rate (about 8 orders of magnitude) under wide temperature (3.6-300 °C) and pH (1.20-12.40) ranges. Under slightly acidic conditions (pH 5-7) the new rate law predicts a minimum rate zone that was not observed before. In order to confirm whether this minimum rate zone does exist, three SPBE (single-point-batch-experiment) of albite dissolution were conducted at pH 5 and temperatures of 3.6, 25 and 50 °C. The SPBE experiments confirm the existence of minimum rate zone predicted by the independent new rate law. The new rate law

  17. Alkaline and alkaline earth metal phosphate halides and phosphors

    DOEpatents

    Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

    2012-11-13

    Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

  18. Limits for alkaline detoxification of dilute-acid lignocellulose hydrolysates.

    PubMed

    Nilvebrant, Nils-Olof; Persson, Per; Reimann, Anders; De Sousa, Filipe; Gorton, Lo; Jönsson, Leif J

    2003-01-01

    In addition to fermentable sugars, dilute-acid hydrolysates of lignocellulose contain compounds that inhibit fermenting microorganisms, such as Saccharomyces cerevisiae. Previous results show that phenolic compounds and furan aldehydes, and to some extent aliphatic acids, act as inhibitors during fermentation of dilute-acid hydrolysates of spruce. Treatment of lignocellulose hydrolysates with alkali, usually in the form of overliming to pH 10.0, has been frequently employed as a detoxification method to improve fermentability. A spruce dilute-acid hydrolysate was treated with NaOH in a factorial design experiment, in which the pH was varied between 9.0 and 12.0, the temperature between 5 and 80 degrees C, and the time between 1 and 7 h. Already at pH 9.0, >25% of the glucose was lost when the hydrolysate was treated at 80 degrees C for 1 h. Among the monosaccharides, xylose was degraded faster under alkaline conditions than the hexoses (glucose, mannose, and galactose), which, in turn, were degraded faster than arabinose. The results suggest that alkali treatment of hydrolysates can be performed at temperatures below 30 degrees C at any pH between 9.0 and 12.0 without problems with sugar degradation or formation of inhibiting aliphatic acids. Treatment with Ca(OH)2 instead of NaOH resulted in more substantial degradation of sugars. Under the harsher conditions of the factorial design experiment, the concentrations of furfural and 5-hydroxymethylfurfural decreased while the total phenolic content increased. The latter phenomenon was tentatively attributed to fragmentation of soluble aromatic oligomers in the hydrolysate. Separate phenolic compounds were affected in different ways by the alkaline conditions with some compounds showing an increase in concentration while others decreased. In conclusion, the conditions used for detoxification with alkali should be carefully controlled to optimize the positive effects and minimize the degradation of fermentable sugars.

  19. 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.

  20. pH distributions in spontaneous and isotransplanted rat tumours.

    PubMed Central

    Kallinowski, F.; Vaupel, P.

    1988-01-01

    Spontaneous mammary tumours of the rat with various degrees of malignancy exhibit similar tissue pH distributions. The mean pH (+/- s.d.) of dysplasia is 7.05 +/- 0.20. In benign tumours the mean pH is 6.95 +/- 0.19 and in malignant tumours it is 6.94 +/- 0.19. In contrast, tumours with the same degree of malignancy but different histologies show different pH distributions. Benign tumours with a higher percentage of fibrous tissue exhibit less acidic pH values than those with larger portions of epithelial cells (delta pH = 0.38 pH units). The pH distribution in the benign tumours is independent of the tumour wet weight up to stages of very advanced growth. In the malignant tumours, a trend towards more acidic pH values is observed as the tumour mass enlarges. However, in tissue areas within a malignant tumour with gross, long-established necrosis the pH distribution is shifted towards more alkaline pH values. The pH distributions in spontaneous rat tumours are not significantly different from those obtained in isotransplanted Yoshida sarcomas (6.87 +/- 0.21). In the Yoshida sarcomas, mean pH values do not correlate with tumour size. However, a pH gradient from the rim to the centre of the tumours is found which coincides with the development of small, disseminated necroses in the tumour centre. It is concluded that pathology-related variations of tumour pH may be more important than the mode of tumour origin or the degree of malignancy. PMID:3179183

  1. Bacterial community responses to a gradient of alkaline mountaintop mine drainage in Central Appalachian streams.

    PubMed

    Bier, Raven L; Voss, Kristofor A; Bernhardt, Emily S

    2015-06-01

    Microbial community composition and diversity change along chemical gradients, leading to the expectation that microbial community information might provide new gradient characterizations. Here we examine stream bacteria composition and diversity along a strong chemical gradient in Central Appalachian streams. Coal mining in the region generates alkaline mine drainage (AlkMD), causing dramatic increases in conductivity, alkalinity, sulfate and metals sufficient to degrade stream macrobiota communities throughout the ecoregion. In this study, we examined the relationship between water and biofilm chemistry and biofilm bacteria taxonomic composition in streams where active and reclaimed surface coal mines occupied 0-96% of watershed surface area. We incubated wood veneers in each stream site for 4 months to develop biofilms on similar substrates. We sampled water chemistry at the time of deployment and collection, and after 1 month. Following incubation, we collected biofilms for microbial and chemical characterization. Microbial composition was determined by pyrosequencing 16S rRNA amplicons. Biofilm subsamples were analyzed by inductively coupled plasma mass spectrometry to determine metal concentrations. Our results show that microbial community composition differed significantly between AlkMD-exposed and AlkMD-unexposed sites, and that compositional dissimilarity increased with AlkMD loading. Diversity was not correlated with pH or extent of upstream mining, but instead correlated with biofilm concentrations of Cd, Mn, Zn and Ni. Within mined sites, the extent of upstream mining was negatively correlated with taxonomic richness. Despite major compositional shifts, functional capacity predicted with PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) correlated with mining in only 3 of 43 level-2 KEGG (Kyoto Encyclopedia of Genes and Genomes) Orthology groups.

  2. Bacterial community responses to a gradient of alkaline mountaintop mine drainage in Central Appalachian streams

    PubMed Central

    Bier, Raven L; Voss, Kristofor A; Bernhardt, Emily S

    2015-01-01

    Microbial community composition and diversity change along chemical gradients, leading to the expectation that microbial community information might provide new gradient characterizations. Here we examine stream bacteria composition and diversity along a strong chemical gradient in Central Appalachian streams. Coal mining in the region generates alkaline mine drainage (AlkMD), causing dramatic increases in conductivity, alkalinity, sulfate and metals sufficient to degrade stream macrobiota communities throughout the ecoregion. In this study, we examined the relationship between water and biofilm chemistry and biofilm bacteria taxonomic composition in streams where active and reclaimed surface coal mines occupied 0–96% of watershed surface area. We incubated wood veneers in each stream site for 4 months to develop biofilms on similar substrates. We sampled water chemistry at the time of deployment and collection, and after 1 month. Following incubation, we collected biofilms for microbial and chemical characterization. Microbial composition was determined by pyrosequencing 16S rRNA amplicons. Biofilm subsamples were analyzed by inductively coupled plasma mass spectrometry to determine metal concentrations. Our results show that microbial community composition differed significantly between AlkMD-exposed and AlkMD-unexposed sites, and that compositional dissimilarity increased with AlkMD loading. Diversity was not correlated with pH or extent of upstream mining, but instead correlated with biofilm concentrations of Cd, Mn, Zn and Ni. Within mined sites, the extent of upstream mining was negatively correlated with taxonomic richness. Despite major compositional shifts, functional capacity predicted with PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) correlated with mining in only 3 of 43 level-2 KEGG (Kyoto Encyclopedia of Genes and Genomes) Orthology groups. PMID:25500511

  3. Alkaline flocculation of Phaeodactylum tricornutum induced by brucite and calcite

    SciTech Connect

    Vandamme, Dries; Pohl, Philip I.; Beuckels, Annelies; Foubert, Imogen; Brady, Patrick Vane; Muylaert, Koenraad; Hewson, John C.

    2015-08-20

    Alkaline flocculation holds great potential as a low-cost harvesting method for marine microalgae biomass production. Alkaline flocculation is induced by an increase in pH and is related to precipitation of calcium and magnesium salts. In this study, we used the diatom Phaeodactylum tricornutum as model organism to study alkaline flocculation of marine microalgae cultured in seawater medium. Flocculation started when pH was increased to 10 and flocculation efficiency reached 90% when pH was 10.5, which was consistent with precipitation modeling for brucite or Mg(OH)2. Compared to freshwater species, more magnesium is needed to achieve flocculation (>7.5 mM). Zeta potential measurements suggest that brucite precipitation caused flocculation by charge neutralization. When calcium concentration was 12.5 mM, flocculation was also observed at a pH of 10. Furthermore, zeta potential remained negative up to pH 11.5, suggesting that precipitated calcite caused flocculation by a sweeping coagulation mechanism.

  4. Production of alkaline cellulase by fungi isolated from an undisturbed rain forest of peru.

    PubMed

    Vega, Karin; Villena, Gretty K; Sarmiento, Victor H; Ludeña, Yvette; Vera, Nadia; Gutiérrez-Correa, Marcel

    2012-01-01

    Alkaline cellulase producing fungi were isolated from soils of an undisturbed rain forest of Peru. The soil dilution plate method was used for the enumeration and isolation of fast growing cellulolytic fungi on an enriched selective medium. Eleven out of 50 different morphological colonies were finally selected by using the plate clearing assay with CMC as substrate at different pH values. All 11 strains produced cellulases in liquid culture with activities at alkaline pH values without an apparent decrease of them indicating that they are true alkaline cellulase producers. Aspergillus sp. LM-HP32, Penicillium sp. LM-HP33, and Penicillium sp. LM-HP37 were the best producers of FP cellulase (>3 U mL(-1)) with higher specific productivities (>30 U g(-1) h(-1)). Three strains have been found suitable for developing processes for alkaline cellulase production. Soils from Amazonian rain forests are good sources of industrial fungi with particular characteristics. The results of the present study are of commercial and biological interest. Alkaline cellulases may be used in the polishing and washing of denim processing of the textile industry.

  5. Statistical optimization of alkaline protease production from Penicillium citrinum YL-1 under solid-state fermentation.

    PubMed

    Xiao, Yun-Zhu; Wu, Duan-Kai; Zhao, Si-Yang; Lin, Wei-Min; Gao, Xiang-Yang

    2015-01-01

    Proteases from halotolerant and halophilic microorganisms were found in traditional Chinese fish sauce. In this study, 30 fungi were isolated from fermented fish sauce in five growth media based on their morphology. However, only one strain, YL-1, which was identified as Penicillium citrinum by internal transcribed spacer (ITS) sequence analysis, can produce alkaline protease. This study is the first to report that a protease-producing fungus strain was isolated and identified in traditional Chinese fish sauce. Furthermore, the culture conditions of alkaline protease production by P. citrinum YL-1 in solid-state fermentation were optimized by response surface methodology. First, three variables including peptone, initial pH, and moisture content were selected by Plackett-Burman design as the significant variables for alkaline protease production. The Box-Behnken design was then adopted to further investigate the interaction effects between the three variables on alkaline protease production and determine the optimal values of the variables. The maximal production (94.30 U/mL) of alkaline protease by P. citrinum YL-1 took place under the optimal conditions of peptone, initial pH, and moisture content (v/w) of 35.5 g/L, 7.73, and 136%, respectively.

  6. The Origin of Life in Alkaline Hydrothermal Vents.

    PubMed

    Sojo, Victor; Herschy, Barry; Whicher, Alexandra; Camprubí, Eloi; Lane, Nick

    2016-02-01

    Over the last 70 years, prebiotic chemists have been very successful in synthesizing the molecules of life, from amino acids to nucleotides. Yet there is strikingly little resemblance between much of this chemistry and the metabolic pathways of cells, in terms of substrates, catalysts, and synthetic pathways. In contrast, alkaline hydrothermal vents offer conditions similar to those harnessed by modern autotrophs, but there has been limited experimental evidence that such conditions could drive prebiotic chemistry. In the Hadean, in the absence of oxygen, alkaline vents are proposed to have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with relatively acidic ocean waters rich in CO2, through a labyrinth of interconnected micropores with thin inorganic walls containing catalytic Fe(Ni)S minerals. The difference in pH across these thin barriers produced natural proton gradients with equivalent magnitude and polarity to the proton-motive force required for carbon fixation in extant bacteria and archaea. How such gradients could have powered carbon reduction or energy flux before the advent of organic protocells with genes and proteins is unknown. Work over the last decade suggests several possible hypotheses that are currently being tested in laboratory experiments, field observations, and phylogenetic reconstructions of ancestral metabolism. We analyze the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria to propose a possible ancestral mechanism of CO2 reduction in alkaline hydrothermal vents. Based on this mechanism, we show that the evolution of active ion pumping could have driven the deep divergence of bacteria and archaea.

  7. Alkaline phytase from lily pollen: Investigation of biochemical properties.

    PubMed

    Jog, Sonali P; Garchow, Barry G; Mehta, Bakul Dhagat; Murthy, Pushpalatha P N

    2005-08-15

    Phytases catalyze the hydrolysis of phytic acid (InsP6, myo-inositol hexakisphosphate), the most abundant inositol phosphate in cells. In cereal grains and legumes, it constitutes 3-5% of the dry weight of seeds. The inability of humans and monogastric animals such as swine and poultry to absorb complexed InsP6 has led to nutritional and environmental problems. The efficacy of supplemental phytases to address these issues is well established; thus, there is a need for phytases with a range of biochemical and biophysical properties for numerous applications. An alkaline phytase that shows unique catalytic properties was isolated from plant tissues. In this paper, we report on the biochemical properties of an alkaline phytase from pollen grains of Lilium longiflorum. The enzyme exhibits narrow substrate specificity, it hydrolyzed InsP6 and para-nitrophenyl phosphate (pNPP). Alkaline phytase followed Michaelis-Menten kinetics with a K(m) of 81 microM and V(max) of 217 nmol Pi/min/mg with InsP6 and a K(m) of 372 microM and V(max) of 1272 nmol Pi/min/mg with pNPP. The pH optimum was 8.0 with InsP6 as the substrate and 7.0 with pNPP. Alkaline phytase was activated by calcium and inactivated by ethylenediaminetetraacetic acid; however, the enzyme retained a low level of activity even in Ca2+-free medium. Fluoride as well as myo-inositol hexasulfate did not have any inhibitory affect, whereas vanadate inhibited the enzyme. The enzyme was activated by sodium chloride and potassium chloride and inactivated by magnesium chloride; the activation by salts followed the Hofmeister series. The temperature optimum for hydrolysis is 55 degrees C; the enzyme was stable at 55 degrees C for about 30 min. The enzyme has unique properties that suggest the potential to be useful as a feed supplement.

  8. [A Contrastive Study on Salt-alkaline Resistance and Removal Efficiency of Nitrogen and Phosphorus by Phragmites australis and Typha angustifolia in Coastal Estuary Area].

    PubMed

    Chen, You-yuan; Sun, Ping; Chen, Guang-lin; Wang, Ning-ning

    2015-04-01

    The salt and alkali contents were so high that the ecological landscape was depressed in water body of a coastal estuary area. Screening some plants which could not only tolerate saline-alkaline but also effectively remove nitrogen and phosphorus was therefore in urgent need. The tolerance range and removal rate of nitrogen and phosphorus by Phragmites australis and Typha angustifolia under salt and pH stress were investigated by hydroponic experiments. The results showed that Phragmites australis could tolerate at least 10 per thousand salinity and pH 8.5, while Typha angustifolia tolerated 7.5 per thousand salinity and pH 8.0. Combined with the change of the growth and physiological indexes (relative conductivity, proline, chlorophyll and root activity), the salt resistance of Phragmites australis was stronger than that of Typha angustifolia. Under salt stress, the removal rate of ammonia nitrogen of Phragmites australis was higher. The removal rates of nitrate nitrogen and phosphorus of Typha angustifolia were 2.5% and 7.3% higher than those of Phragmites australis in average, respectively, because of the high biomass of Typha angustifolias. The total nitrogen removal rate was equivalent. Under pH stress, the removal rate of ammonia nitrogen and total phosphorus of Phragmites australis was a little higher than that of Typha angustifolia. However, Typha angustifolia had a higher removal rate of total nitrogen, which was 8.2% higher than that of Phragmites australis. All the analysis showed that both Phragmites australis and Typha angustifolia could be used as alternative plants to grow and remove nitrogen and phosphorus in the high salt-alkaline water body in coastal estuary area.

  9. Prebiotic Synthesis of Protobiopolymers Under Alkaline Ocean Conditions

    NASA Astrophysics Data System (ADS)

    Ruiz-Bermejo, Marta; Rivas, Luis A.; Palacín, Arantxa; Menor-Salván, César; Osuna-Esteban, Susana

    2011-08-01

    Clasically, prebiotic chemistry has focused on the production and identification of simple organic molecules, many of them forming part of "intractable polymers" named tholins. In a previous work, we demonstrated that in experiments using an external energy source and inorganic carbon the aqueous aerosols improved the formation of hydrophilic tholins. Herein, we elucidate the role of pH (from 4 to 12) in prebiotic experiments using saline aqueous aerosols, spark discharges and an atmosphere containing CH4. At all values of pH, the saline aqueous aerosols increased the production of a significant variety of carboxylic acids that could have been present in a primitive Krebs cycle. Moreover, the study for the first time of hydrophilic tholins by 2-D electrophoresis revealed that these are formed by a set of unexpected heavy polymeric species. The initial alkaline conditions significantly increased both the apparent molecular weight of polymeric species up to 80 kDa and their diversity. We propose the term of protobiopolymers to denote those polymeric species fractionated by 2-D electrophoresis since these are formed by biomolecules present in living systems and show diversity in length as well as in functional groups. Thus, aerosols formed in simulated alkaline ocean conditions could provide an optimal medium for the formation of the primeval materials that could be precursors to the emergence of life.

  10. Interfacial activity in alkaline flooding enhanced oil recovery

    SciTech Connect

    Chan, M.K.

    1981-01-01

    The ionization of long-chained organic acids in the crude oil to form soaps was shown to be primarily responsible for the lowering of oil-water interfacial tension at alkaline pH. These active acids can be concentrated by silica gel chromatography into a minor polar fraction. An equilibrium chemical model was proposed based on 2 competing reactions: the ionization of acids to form active anions, and the formation of undissociated soap between acid anions and sodium ions. It correlates the interfacial activity with the interfacial concentration of active acid anions which is expressed in terms of the concentrations of the chemical species in the system. The model successfully predicts the observed oil-alkaline solution interfacial phenomenon, including its dependence on pH, alkali and salt concentrations, type of acid present and type of soap formed. Flooding at different alkali concentrations to activate different acid species present in the crude was shown to give better recovery than flooding at a single high alkali concentration. Treating the crude oil with a dilute solution of mineral acids liberates additional free active acids and yields better interfacial activity during subsequent alkali contact.

  11. Permeability Modification Using a Reactive Alkaline-Soluble Biopolymer

    SciTech Connect

    Sandra L. Fox; Xina Xie; Greg Bala

    2004-11-01

    Polymer injection has been used in reservoirs to alleviate contrasting permeability zones to enhance oil recovery (EOR). Polymer technology relies mainly on the use of polyacrylamides cross-linked by a hazardous metal or organic. Contemporary polymer plugging has investigated the stimulation of in-situ microorganisms to produce polymers (Jenneman et. al., 2000) and the use of biocatalysts to trigger gelling (Bailey et. al., 2000). The use of biological polymers are advantageous in that they can block high permeability areas, are environmentally friendly, and have potential to form reversible gels without the use of hazardous cross-linkers. Recent efforts have produced a reactive alkaline-soluble biopolymer from Agrobacterium species ATCC # 31749 that gels upon decreasing the pH of the polymeric solution. Microbial polymers are of interest due to their potential cost savings, compared to conventional use of synthetic chemical polymers. Numerous microorganisms are known to produce extracellular polysaccharides. One microbiological polymer of interest is curdlan, â - (1, 3) glucan, which has demonstrated gelling properties by a reduction in pH. The focus of this study was to determine the impact an alkaline-soluble biopolymer can have on sandstone permeability.

  12. Polyhydroxyflavones as extractants. Communication 7. Solvent extraction of europrium complexes with morin from alkaline media

    SciTech Connect

    Blank, A.B.

    1985-09-01

    This paper studies the analytical application of europium (III)-morin complex which is formed in alkaline medium and has an intense color. The extent of europium extraction was determined by adding to the extract a morin solution in isoamyl alcohol in a 50-100-fold excess with respect to europium. The dependence of the optical density of the extracts on the ph in the system europium (III)-morin-water-organic solvent for different excesses of the reagent is shown: this indicates formation of two extractable complexes, one being dominant in the pH range 4-7, the other at pH greater than or equal to 8.5. The extraction of the europium (III)-morin complex from alkaline solution is used for direct extraction-photometric determination of europium(III) in compounds of elements having amphoteric properties or forming amines (Zns, Mo0/sub 3/).

  13. Accuracy of the evaluation method for alkaline agents’ bactericidal efficacies in solid, and the required time of bacterial inactivation

    PubMed Central

    HAKIM, Hakimullah; TOYOFUKU, Chiharu; OTA, Mari; SUZUKI, Mayuko; KOMURA, Miyuki; YAMADA, Masashi; ALAM, Md. Shahin; SANGSRIRATANAKUL, Natthanan; SHOHAM, Dany; TAKEHARA, Kazuaki

    2016-01-01

    An alkaline agent, namely food additive grade calcium hydroxide (FdCa (OH)2) in the powder form, was evaluated for its bactericidal efficacies in chicken feces at pH 13. The point for this evaluation was neutralization of the alkaline agent’s pH at the time of bacterial recovery, since otherwise the results are substantially misleading. Without neutralization of the FdCa (OH)2 pH, the spiked bacteria were killed within min at the time of recovery in aqueous phase, but not in the solid form in feces, hence, it has been demonstrated that when bacteria were in solid, it took longer time than in liquid for the alkaline agent to inactivate them down to the acceptable level (≥3 log10 CFU/ml). PMID:27890906

  14. Closed type alkaline storage battery

    SciTech Connect

    Hayama, H.

    1980-06-10

    The alkaline storage battery employs a metallic hat shaped terminal closure which has a piercing needle as well as a puncturable metallic diaphragm positioned below the piercing needle. The needle is fixed by caulking at its peripheral edge portion to a edge of the closure. A comparatively thick and hard metal plate is placed on the inner surface of the diaphragm and is applied to an open portion of a tubular metallic container which has a battery element. A peripheral edge portion of the closure, the diaphragm and the metallic plate are clamped in airtight relationship through a packing between the caulked end portion and an inner annular step portion of the metallic container of the battery. A lead wire extends from one polarity electrode of the battery element and is connected to a central portion of the metallic plate.

  15. Tracking Catalyst Redox States and Reaction Dynamics in Ni-Fe Oxyhydroxide Oxygen Evolution Reaction Electrocatalysts: The Role of Catalyst Support and Electrolyte pH.

    PubMed

    Görlin, Mikaela; Ferreira de Araújo, Jorge; Schmies, Henrike; Bernsmeier, Denis; Dresp, Sören; Gliech, Manuel; Jusys, Zenonas; Chernev, Petko; Kraehnert, Ralph; Dau, Holger; Strasser, Peter

    2017-02-08

    Ni-Fe oxyhydroxides are the most active known electrocatalysts for the oxygen evolution reaction (OER) in alkaline electrolytes and are therefore of great scientific and technological importance in the context of electrochemical energy conversion. Here we uncover, investigate, and discuss previously unaddressed effects of conductive supports and the electrolyte pH on the Ni-Fe(OOH) catalyst redox behavior and catalytic OER activity, combining in situ UV-vis spectro-electrochemistry, operando electrochemical mass spectrometry (DEMS), and in situ cryo X-ray absorption spectroscopy (XAS). Supports and pH > 13 strongly enhanced the precatalytic voltammetric charge of the Ni-Fe oxyhydroxide redox peak couple, shifted them more cathodically, and caused a 2-3-fold increase in the catalytic OER activity. Analysis of DEMS-based faradaic oxygen efficiency and electrochemical UV-vis traces consistently confirmed our voltammetric observations, evidencing both a more cathodic O2 release and a more cathodic onset of Ni oxidation at higher pH. Using UV-vis, which can monitor the amount of oxidized Ni(+3/+4) in situ, confirmed an earlier onset of the redox process at high electrolyte pH and further provided evidence of a smaller fraction of Ni(+3/+4) in mixed Ni-Fe centers, confirming the unresolved paradox of a reduced metal redox activity with increasing Fe content. A nonmonotonic super-Nernstian pH dependence of the redox peaks with increasing Fe content-displaying Pourbaix slopes as steep as -120 mV/pH-suggested a two proton-one electron transfer. We explain and discuss the experimental pH effects using refined coupled (PCET) and decoupled proton transfer-electron transfer (PT/ET) schemes involving negatively charged oxygenate ligands generated at Fe centers. Together, we offer new insight into the catalytic reaction dynamics and associated catalyst redox chemistry of the most important class of alkaline OER catalysts.

  16. Structural analysis of alkaline β-mannanase from alkaliphilic Bacillus sp. N16-5: implications for adaptation to alkaline conditions.

    PubMed

    Zhao, Yueju; Zhang, Yunhua; Cao, Yang; Qi, Jianxun; Mao, Liangwei; Xue, Yanfen; Gao, Feng; Peng, Hao; Wang, Xiaowei; Gao, George F; Ma, Yanhe

    2011-01-28

    Significant progress has been made in isolating novel alkaline β-mannanases, however, there is a paucity of information concerning the structural basis for alkaline tolerance displayed by these β-mannanases. We report the catalytic domain structure of an industrially important β-mannanase from the alkaliphilic Bacillus sp. N16-5 (BSP165 MAN) at a resolution of 1.6 Å. This enzyme, classified into subfamily 8 in glycosyl hydrolase family 5 (GH5), has a pH optimum of enzymatic activity at pH 9.5 and folds into a classic (β/α)(8)-barrel. In order to gain insight into molecular features for alkaline adaptation, we compared BSP165 MAN with previously reported GH5 β-mannanases. It was revealed that BSP165 MAN and other subfamily 8 β-mannanases have significantly increased hydrophobic and Arg residues content and decreased polar residues, comparing to β-mannanases of subfamily 7 or 10 in GH5 which display optimum activities at lower pH. Further, extensive structural comparisons show alkaline β-mannanases possess a set of distinctive features. Position and length of some helices, strands and loops of the TIM barrel structures are changed, which contributes, to a certain degree, to the distinctly different shaped (β/α)(8)-barrels, thus affecting the catalytic environment of these enzymes. The number of negatively charged residues is increased on the molecular surface, and fewer polar residues are exposed to the solvent. Two amino acid substitutions in the vicinity of the acid/base catalyst were proposed to be possibly responsible for the variation in pH optimum of these homologous enzymes in subfamily 8 of GH5, identified by sequence homology analysis and pK(a) calculations of the active site residues. Mutational analysis has proved that Gln91 and Glu226 are important for BSP165 MAN to function at high pH. These findings are proposed to be possible factors implicated in the alkaline adaptation of GH5 β-mannanases and will help to further understanding of

  17. Perturbation Analysis of Calcium, Alkalinity and Secretion during Growth of Lily Pollen Tubes

    PubMed Central

    Winship, Lawrence J.; Rounds, Caleb; Hepler, Peter K.

    2016-01-01

    Pollen tubes grow by spatially and temporally regulated expansion of new material secreted into the cell wall at the tip of the tube. A complex web of interactions among cellular components, ions and small molecule provides dynamic control of localized expansion and secretion. Cross-correlation studies on oscillating lily (Lilium formosanum Wallace) pollen tubes showed that an increase in intracellular calcium follows an increase in growth, whereas the increase in the alkaline band and in secretion both anticipate the increase in growth rate. Calcium, as a follower, is unlikely to be a stimulator of growth, whereas the alkaline band, as a leader, may be an activator. To gain further insight herein we reversibly inhibited growth with potassium cyanide (KCN) and followed the re-establishment of calcium, pH and secretion patterns as growth resumed. While KCN markedly slows growth and causes the associated gradients of calcium and pH to sharply decline, its removal allows growth and vital processes to fully recover. The calcium gradient reappears before growth restarts; however, it is preceded by both the alkaline band and secretion, in which the alkaline band is slightly advanced over secretion. Thus the pH gradient, rather than the tip-focused calcium gradient, may regulate pollen tube growth. PMID:28042810

  18. Electrophoretic separation of alkaline and acid phosphatase isoenzymes from the pulp of monkey teeth.

    PubMed

    Franzén, A; Hasselgren, G

    1978-01-01

    Monkey pulps were homogenized in a Triton tris solution. After three centrifugation steps (800, 20000, and 105000 g) the supernatant was applied on acryl amide columns at pH 7.5 in a tris-diethyl barbituric acid buffer. Electrophoresis was performed at a constant current of 2.5 mA per gel column at 18--20 degrees C. Incubations for alkaline phosphatase (E.C. 3.1.3.1) were carried out at pH 8.3 using naphthol-AS-MX-phosphate as substrate and Fast Red Violet LB salt as coupler. Incubations for acid phosphatase (E.C. 3.1.3.2) were undertaken at pH 5.0 using alpha-naphtyl phosphate as substrate and hexazotized pararosanilin as coupling agent. After the incubations for alkaline phosphatase as well as acid phosphatase two bands showing enzyme activity were demonstrated. By means of treatment with heat (56 degrees C) prior to incubation or addition of vanadate or pyrophosphate to the incubation medium it was shown that the main part of the fast moving alkaline phosphatase band was sensitive to these procedures. The alkaline phosphatase of the slow moving band appeared to be resistant to heat or the addition of inhibitors.

  19. Cultivation of marine shrimp in biofloc technology (BFT) system under different water alkalinities.

    PubMed

    Piérri, V; Valter-Severino, D; Goulart-de-Oliveira, K; Manoel-do-Espírito-Santo, C; Nascimento-Vieira, F; Quadros-Seiffert, W

    2015-08-01

    The aim of this study was to evaluate the influence of different levels of alkalinity for the superintensive cultivation of marine shrimp Litopenaeus vannamei in biofloc system. A total of 12 experimental circular units of 1000L were used supplied with 850L water from a nursery, populated at a density of 165 shrimps.m-3 and average weight of 5.6 g. The treatments, in triplicate, consisted in four levels of alkalinity in the water: 40, 80, 120 and 160 mg.L-1 of calcium carbonate. To correct the alkalinity was used calcium hydroxide (CaOH). It was observed a decrease in pH of the water in the treatments with lower alkalinity (p<0.05). The total suspended settleable solids were also lower in the treatment of low alkalinity. No significant difference was observed in other physico-chemical and biological parameters in the water quality assessed, as well as the zootechnical parameters of cultivation between treatments (p≥0.05). The results of survival and growth rate of shrimps were considered suitable for the cultivation system used in the different treatments. The cultivation of marine shrimp Litopenaeus vannamei in biofloc at density of 165 shrimps.m-3 can be performed in waters with alkalinity between 40 and 160 mg.L-1 of CaCO3, without compromising the zootechnical indexes of cultivation.

  20. Re-epithelialization of the Buccal Mucosa after Alkaline Chemical Injury.

    PubMed

    Takaichi, Saneyuki; Muramatsu, Takashi; Lee, Jong-Min; Jung, Han-Sung; Shinozaki, Naoshi; Katakura, Akira; Yamane, Gen-Yuki

    2014-01-01

    Alkaline conditions in the oral cavity may be caused by a variety of stimuli, including tobacco products, antacids, alkaline drinking water and bicarbonate toothpaste. However, the effects of an alkaline pH on the oral mucosa had not been elucidated. The purpose of this study was to investigate how basal keratinocytes are actively involved in re-epithelialization after alkaline chemical injury. We generated epithelial defects in the oral mucosa of mice by applying an alkaline chemical, and the localization of cytokeratin 13, cytokeratin 14, PCNA and p63 was investigated during the re-epithelialization process. PCNA- and p63-positive staining was seen in basal cells covering the wound surface at 1 day after the chemical injury. Cytokeratin 14-positive and PCNA-negative basal keratinocytes were localized in a few layers of the wound epithelium during epithelial outgrowth. Cytokeratin 14-positive and PCNA-positive basal keratinocytes, indicating proliferation, were localized over the entire layer of the epithelium at the wound margin. These results imply that basal keratinocytes at the wound margin migrate to the wound surface, provoke differentiation and keratinization during epithelial outgrowth and that epithelial cells are supplied from the wound margin to the epithelial outgrowth after alkaline chemical injury.

  1. Anditalea andensis ANESC-ST--An Alkaliphilic Halotolerant Bacterium Capable of Electricity Generation under Alkaline-Saline Conditions.

    PubMed

    Shi, Wei; Wang, Victor Bochuan; Zhao, Cui-E; Zhang, Qichun; Loo, Say Chye Joachim; Yang, Liang; Xu, Chenjie

    2015-01-01

    A great challenge in wastewater bioremediation is the sustained activity of viable microorganisms, which can contribute to the breakdown of waste contaminants, especially in alkaline pH conditions. Identification of extremophiles with bioremediation capability can improve the efficiency of wastewater treatment. Here, we report the discovery of an electrochemically active alkaliphilic halotolerant bacterium, Anditalea andensis ANESC-ST (=CICC10485T=NCCB 100412T), which is capable of generating bioelectricity in alkaline-saline conditions. A. andensis ANESC-ST was shown to grow in alkaline conditions between pH 7.0-11.0 and also under high salt condition (up to 4 wt% NaCl). Electrical output was further demonstrated in microbial fuel cells (MFCs) with an average current density of ~0.5 µA/cm2, even under the harsh condition of 4 wt% NaCl and pH 9.0. Subsequent introduction of secreted extracellular metabolites into MFCs inoculated with Escherichia coli or Pseudomonas aeruginosa yielded enhanced electrical output. The ability of A. andensis ANESC-ST to generate energy under alkaline-saline conditions points towards a solution for bioelectricity recovery from alkaline-saline wastewater. This is the first report of A.andensis ANESC-ST producing bioelectricity at high salt concentration and pH.

  2. Regulation of neuronal connexin-36 channels by pH.

    PubMed

    González-Nieto, Daniel; Gómez-Hernández, Juan M; Larrosa, Belén; Gutiérrez, Cristina; Muñoz, María D; Fasciani, Ilaria; O'Brien, John; Zappalà, Agata; Cicirata, Federico; Barrio, Luis C

    2008-11-04

    Neurotransmission through electrical synapses plays an important role in the spike synchrony among neurons and oscillation of neuronal networks. Indeed, electrical transmission has been implicated in the hypersynchronous electrical activity of epilepsy. We have investigated the influence of intracellular pH on the strength of electrical coupling mediated by connexin36 (Cx36), the principal gap junction protein in the electrical synapses of vertebrates. In striking contrast to other connexin isoforms, the activity of Cx36 channels decreases following alkalosis rather than acidosis when it is expressed in Xenopus oocytes and N2A cells. This uncoupling of Cx36 channels upon alkalinization occurred in the vertebrate orthologues analyzed (human, mouse, chicken, perch, and skate). While intracellular acidification caused a mild or moderate increase in the junctional conductance of virtually all these channels, the coupling of the skate Cx35 channel was partially blocked by acidosis. The mutational analysis suggests that the Cx36 channels may contain two gating mechanisms operating with opposing sensitivity to pH. One gate, the dominant mechanism, closes for alkalosis and it probably involves an interaction between the C- and N-terminal domains, while a secondary acid sensing gate only causes minor, albeit saturating, changes in coupling following acidosis and alkalosis. Thus, we conclude that neuronal Cx36 channels undergo unique regulation by pH(i) since their activity is inhibited by alkalosis rather than acidosis. These data provide a novel basis to define the relevance and consequences of the pH-dependent modulation of Cx36 synapses under physiological and pathological conditions.

  3. Constructing and Screening a Metagenomic Library of a Cold and Alkaline Extreme Environment.

    PubMed

    Glaring, Mikkel A; Vester, Jan K; Stougaard, Peter

    2017-01-01

    Natural cold or alkaline environments are common on Earth. A rare combination of these two extremes is found in the permanently cold (less than 6 °C) and alkaline (pH above 10) ikaite columns in the Ikka Fjord in Southern Greenland. Bioprospecting efforts have established the ikaite columns as a source of bacteria and enzymes adapted to these conditions. They have also highlighted the limitations of cultivation-based methods in this extreme environment and metagenomic approaches may provide access to novel extremophilic enzymes from the uncultured majority of bacteria. Here, we describe the construction and screening of a metagenomic library of the prokaryotic community inhabiting the ikaite columns.

  4. A newly high alkaline lipase: an ideal choice for application in detergent formulations

    PubMed Central

    2011-01-01

    Background Bacterial lipases received much attention for their substrate specificity and their ability to function in extreme environments (pH, temperature...). Many staphylococci produced lipases which were released into the culture medium. Reports of thermostable lipases from Staphylococcus sp. and active in alkaline conditions are not previously described. Results A newly soil-isolated Staphylococcus sp. strain ESW secretes an induced lipase in the culture medium. The effects of temperature, pH and various components in a detergent on the activity and stability of Staphylococcus sp. lipase (SL1) were studied in a preliminary evaluation for use in detergent formulation solutions. The enzyme was highly active over a wide range of pH from 9.0 to 13.0, with an optimum at pH 12.0. The relative activity at pH 13.0 was about 60% of that obtained at pH 12.0. It exhibited maximal activity at 60°C. This novel lipase, showed extreme stability towards non-ionic and anionic surfactants after pre-incubation for 1 h at 40°C, and relative stability towards oxidizing agents. Additionally, the crude enzyme showed excellent stability and compatibility with various commercial solid and liquid detergents. Conclusions These properties added to the high activity in high alkaline pH make this novel lipase an ideal choice for application in detergent formulations. PMID:22123072

  5. Evolution of alkaline phosphatases in primates.

    PubMed Central

    Goldstein, D J; Rogers, C; Harris, H

    1982-01-01

    Alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] in placenta, intestine, liver, kidney, bone, and lung from a variety of primate species has been characterized by quantitative inhibition, thermostability, and immunological studies. Characteristic human placental-type alkaline phosphatase occurs in placentas of great apes (chimpanzee and orangutan) but not in placentas of other primates, including gibbon. It is also present in trace amounts in human lung but not in lung or other tissues of various Old and New World monkeys. However, a distinctive alkaline phosphatase resembling it occurs in substantial amounts in lungs from Old World monkeys but not New World monkeys. It appears that duplication of alkaline phosphatase genes and mutations of genetic elements controlling their tissue expression have occurred relatively recently in mammalian evolution. Images PMID:6950431

  6. Dipstick Spot urine pH does not accurately represent 24 hour urine PH measured by an electrode

    PubMed Central

    Omar, Mohamed; Sarkissian, Carl; Jianbo, Li; Calle, Juan; Monga, Manoj

    2016-01-01

    ABSTRACT Objectives To determine whether spot urine pH measured by dipstick is an accurate representation of 24 hours urine pH measured by an electrode. Materials and Methods We retrospectively reviewed urine pH results of patients who presented to the urology stone clinic. For each patient we recorded the most recent pH result measured by dipstick from a spot urine sample that preceded the result of a 24-hour urine pH measured by the use of a pH electrode. Patients were excluded if there was a change in medications or dietary recommendations or if the two samples were more than 4 months apart. A difference of more than 0.5 pH was considered an inaccurate result. Results A total 600 patients were retrospectively reviewed for the pH results. The mean difference in pH between spot urine value and the 24 hours collection values was 0.52±0.45 pH. Higher pH was associated with lower accuracy (p<0.001). The accuracy of spot urine samples to predict 24-hour pH values of <5.5 was 68.9%, 68.2% for 5.5 to 6.5 and 35% for >6.5. Samples taken more than 75 days apart had only 49% the accuracy of more recent samples (p<0.002). The overall accuracy is lower than 80% (p<0.001). Influence of diurnal variation was not significant (p=0.588). Conclusions Spot urine pH by dipstick is not an accurate method for evaluation of the patients with urolithiasis. Patients with alkaline urine are more prone to error with reliance on spot urine pH. PMID:27286119

  7. Use of limestone for pH control in autotrophic denitrification: continuous flow experiments in pilot-scale packed bed reactors.

    PubMed

    Koenig, A; Liu, L H

    2002-10-23

    The sulfur-utilizing autotrophic denitrification process consumes about 4 g alkalinity (as CaCO(3)) per g NO(3)-N reduced resulting in a decrease of pH. Using limestone as an alkalinity source to control the pH, autotrophic denitrification of synthetic wastewater with varying alkalinity to NO(3)-N ratios was evaluated in pilot-scale packed bed reactors operating in the upflow mode, which contained limestone and sulfur granules in different volumetric ratios. The results demonstrated that limestone supplies effective buffering capacity, if the initial alkalinity of the wastewater is insufficient for complete denitrification. The alkalinity supplied by limestone is a function of hydraulic retention time and the pH, which in turn depends on the extent of biological denitrification and the initial alkalinity to NO(3)-N ratio in the wastewater. The dissolution rate of limestone is inversely proportional to pH for pH values lower than 7.1. It was found that the ratio of influent alkalinity to theoretically required alkalinity in the wastewater should not be lower than 0.5 in order to prevent a decrease in nitrate removal performance. Based on the established chemical-biological interactive relationships, a multilayer approach was proposed to determine the optimum sulfur:limestone ratio for nitrate removal under steady state conditions, taking into account the characteristics of the influent wastewater.

  8. The effect of pH adjustment of 0.5% bupivacaine on the latency of epidural anesthesia.

    PubMed

    Stevens, R A; Chester, W L; Grueter, J A; Schubert, A; Brandon, D; Clayton, B; Spitzer, L

    1989-01-01

    pH adjustment of lidocaine and 2-chloroprocaine has been reported to decrease the latency of epidural anesthesia (EA). The effect of alkalinization of bupivacaine on onset of surgical anesthesia has not been adequately studied to date. To determine what effect raising the pH of 0.5% bupivacaine has on the latency of EA in patients undergoing lower extremity surgery, we performed a randomized, double-blind study. Forty patients were randomly divided into two groups. Group I patients received 15 ml of a local anesthetic (LA) solution containing 0.5% bupivacaine and 0.15 mEq of NaHCO3. Group II patients received 15 ml of a standard solution of 0.5% bupivacaine. Both solutions contained freshly added epinephrine (1:200,000). After injection of LA via Tuohy needle, sensory testing was conducted using a safety pin. The pH of the LA used for Group I was 6.96 +/- 0.01 and for Group II was 5.33 +/- 0.11. No statistically significant difference was found between the anesthetic parameters tested in each group. On this basis, we find no advantage of pH adjustment of 0.5% bupivacaine for EA.

  9. Identification of differentially expressed genes in flax (Linum usitatissimum L.) under saline-alkaline stress by digital gene expression.

    PubMed

    Yu, Ying; Huang, Wengong; Chen, Hongyu; Wu, Guangwen; Yuan, Hongmei; Song, Xixia; Kang, Qinghua; Zhao, Dongsheng; Jiang, Weidong; Liu, Yan; Wu, Jianzhong; Cheng, Lili; Yao, Yubo; Guan, Fengzhi

    2014-10-01

    The salinization and alkalization of soil are widespread environmental problems, and alkaline salt stress is more destructive than neutral salt stress. Therefore, understanding the mechanism of plant tolerance to saline-alkaline stress has become a major challenge. However, little attention has been paid to the mechanism of plant alkaline salt tolerance. In this study, gene expression profiling of flax was analyzed under alkaline-salt stress (AS2), neutral salt stress (NSS) and alkaline stress (AS) by digital gene expression. Three-week-old flax seedlings were placed in 25 mM Na2CO3 (pH11.6) (AS2), 50mM NaCl (NSS) and NaOH (pH11.6) (AS) for 18 h. There were 7736, 1566 and 454 differentially expressed genes in AS2, NSS and AS compared to CK, respectively. The GO category gene enrichment analysis revealed that photosynthesis was particularly affected in AS2, carbohydrate metabolism was particularly affected in NSS, and the response to biotic stimulus was particularly affected in AS. We also analyzed the expression pattern of five categories of genes including transcription factors, signaling transduction proteins, phytohormones, reactive oxygen species proteins and transporters under these three stresses. Some key regulatory gene families involved in abiotic stress, such as WRKY, MAPKKK, ABA, PrxR and ion channels, were differentially expressed. Compared with NSS and AS, AS2 triggered more differentially expressed genes and special pathways, indicating that the mechanism of AS2 was more complex than NSS and AS. To the best of our knowledge, this was the first transcriptome analysis of flax in response to saline-alkaline stress. These data indicate that common and diverse features of saline-alkaline stress provide novel insights into the molecular mechanisms of plant saline-alkaline tolerance and offer a number of candidate genes as potential markers of tolerance to saline-alkaline stress.

  10. Solubility of pllutonium in alkaline salt solutions

    SciTech Connect

    Hobbs, D.T.; Edwards, T.B.

    1993-02-26

    Plutonium solubility data from several studies have been evaluated. For each data set, a predictive model has been developed where appropriate. In addition, a statistical model and corresponding prediction intervals for plutonium solubility as a quadratic function of the hydroxide concentration have been developed. Because of the wide range of solution compositions, the solubility of plutonium can vary by as much as three orders of magnitude for any given hydroxide concentration and still remain within the prediction interval. Any nuclear safety assessments that depend on the maximum amount of plutonium dissolved in alkaline salt solutions should use concentrations at least as great as the upper prediction limits developed in this study. To increase the confidence in the prediction model, it is recommended that additional solubility tests be conducted at low hydroxide concentrations and with all of the other solution components involved. To validate the model for application to actual waste solutions, it is recommended that the plutonium solubilities in actual waste solutions be determined and compared to the values predicted by the quadratic model.

  11. Supplementation of alkaline phytase (Ds11) in whole-wheat bread reduces phytate content and improves mineral solubility.

    PubMed

    Park, Yun-Jong; Park, Jiwon; Park, Ki-Hwan; Oh, Byung-Chul; Auh, Joong-Hyuck

    2011-08-01

    In this study, alkaline phytase was added to whole-wheat bread and the phytate content and mineral profiles were compared to commercially available acidic phytase. At neutral pH, some phytate (approximately 20%) was degraded by endogenous phytase in wheat flour, while 40% of phytate was hydrolyzed by alkaline phytase DS11 and a 35% reduction was observed with acidic phytase. Most of the enzymatic activity occurred during the proofing stage, and the rate of reaction depended on pH. DS11 phytase effectively degraded the phytate level within a 30 min treatment at pH 7; however, at least 60 min was needed with acidic phytase to achieve the same hydrolysis level. Mineral profiles were also dramatically affected by the phytate reduction. The biggest increase was observed in Fe²⁺ by the phytase treatment. The Fe²⁺ content increased 10-fold at pH 7 and 8-fold at pH 5 with alkaline phytase DS11. Alkaline phytase DS11 was shown to be effective at phytate reduction in whole-wheat bread preparation. Additionally, phytate degradation enhanced the mineral availability of bread.

  12. Nanofiber Composite Membranes for Alkaline Fuel Cells: Generation of Compositional, Morphological, and Functional Property Relationships

    DTIC Science & Technology

    2015-12-01

    properties of nanofiber composite anion-exchange membranes for alkaline fuel cells. A new membrane fabrication strategy, utilizing polymer fiber...electrospinning, will be employed to make hydroxide-conducting membranes with an entirely new morphology, where one electrospun polymer provides pathways...for ion conductivity and the second electrospun polymer restricts ionomer swelling and imparts mechanical strength to the membrane. The functional

  13. Metal/Metal Oxide Differential Electrode pH Sensors

    NASA Technical Reports Server (NTRS)

    West, William; Buehler, Martin; Keymeulen, Didier

    2007-01-01

    Solid-state electrochemical sensors for measuring the degrees of acidity or alkalinity (in terms of pH values) of liquid solutions are being developed. These sensors are intended to supplant older electrochemical pH sensors that include glass electrode structures and reference solutions. The older sensors are fragile and subject to drift. The present developmental solid-state sensors are more rugged and are expected to be usable in harsh environments. The present sensors are based on a differential-electrode measurement principle. Each sensor includes two electrodes, made of different materials, in equilibrium with the solution of interest.

  14. The mechanism of hydrolysis of beta-glycerophosphate by kidney alkaline phosphatase.

    PubMed

    Ahlers, J

    1975-09-01

    1. To identify the functional groups that are involved in the conversion of beta-glycerophosphate by alkaline phosphatase (EC 3.1.3.1) from pig kidney, the kinetics of alkaline phosphatase were investigated in the pH range 6.6-10.3 at substrate concentrations of 3 muM-30 mM. From the plots of log VH+ against pH and log VH+/KH+m against pH one functional group with pK = 7.0 and two functional groups with pK = 9.1 were identified. These groups are involved in substrate binding. Another group with pK = 8.8 was found, which in its unprotonated form catalyses substrate conversion. 2. GSH inhibits the alkaline phosphatase reversibly and non-competitively by attacking the bound Zn(II). 3. The influence of the H+ concentration on the activation by Mg2+ ions of alkaline pig kidney phosphate was investigated between pH 8.4 and 10.0. The binding of substrate and activating Mg2+ ions occurs independently at all pH values between 8.4 and 10.0. The activation mechanism is not affected by the H+ concentration. The Mg2+ ions are bound by a functional group with a pK of 10.15. 4. A scheme is proposed for the reaction between enzyme, substrate, Mg2+ and H+ and the overall rate equation is derived. 5. The mechanism of substrate binding and splitting by the functional groups of the active centre is discussed on the basis of a model. Mg2+ seems to play a role as an autosteric effector.

  15. The mechanism of hydrolysis of beta-glycerophosphate by kidney alkaline phosphatase.

    PubMed Central

    Ahlers, J

    1975-01-01

    1. To identify the functional groups that are involved in the conversion of beta-glycerophosphate by alkaline phosphatase (EC 3.1.3.1) from pig kidney, the kinetics of alkaline phosphatase were investigated in the pH range 6.6-10.3 at substrate concentrations of 3 muM-30 mM. From the plots of log VH+ against pH and log VH+/KH+m against pH one functional group with pK = 7.0 and two functional groups with pK = 9.1 were identified. These groups are involved in substrate binding. Another group with pK = 8.8 was found, which in its unprotonated form catalyses substrate conversion. 2. GSH inhibits the alkaline phosphatase reversibly and non-competitively by attacking the bound Zn(II). 3. The influence of the H+ concentration on the activation by Mg2+ ions of alkaline pig kidney phosphate was investigated between pH 8.4 and 10.0. The binding of substrate and activating Mg2+ ions occurs independently at all pH values between 8.4 and 10.0. The activation mechanism is not affected by the H+ concentration. The Mg2+ ions are bound by a functional group with a pK of 10.15. 4. A scheme is proposed for the reaction between enzyme, substrate, Mg2+ and H+ and the overall rate equation is derived. 5. The mechanism of substrate binding and splitting by the functional groups of the active centre is discussed on the basis of a model. Mg2+ seems to play a role as an autosteric effector. PMID:995

  16. Fate of cadmium at the soil-solution interface: a thermodynamic study as influenced by varying pH at South 24 Parganas, West Bengal, India.

    PubMed

    Karak, Tanmoy; Paul, Ranjit Kumar; Das, Sampa; Das, Dilip K; Dutta, Amrit Kumar; Boruah, Romesh K

    2015-11-01

    A study on the sorption kinetics of Cd from soil solution to soils was conducted to assess the persistence of Cd in soil solution as it is related to the leaching, bioavailability, and potential toxicity of Cd. The kinetics of Cd sorption on two non-contaminated alkaline soils from Canning (22° 18' 48.02″ N and 88° 39' 29.0″ E) and Lakshmikantapur (22° 06' 16.61″ N and 88° 19' 08.66″ E) of South 24 Parganas, West Bengal, India, were studied using conventional batch experiment. The variable soil suspension parameters were pH (4.00, 6.00, 8.18, and 9.00), temperatures (308, 318, and 328 K) and Cd concentrations (5-100 mg L(-1)). The average rate coefficient (kavg) and half-life (t1/2) values indicate that the persistence of Cd in soil solution is influenced by both temperature and soil suspension pH. The concentration of Cd in soil solution decreases with increase of temperature; therefore, Cd sorption on the soil-solution interface is an endothermic one. Higher pH decreases the t 1/2 of Cd in soil solution, indicating that higher pH (alkaline) is not a serious concern in Cd toxicity than lower pH (acidic). Based on the energy of activation (Ea) values, Cd sorption in acidic pH (14.76±0.29 to 64.45±4.50 kJ mol(-1)) is a surface control phenomenon and in alkaline pH (9.33±0.09 to 44.60±2.01 kJ mol(-1)) is a diffusion control phenomenon The enthalpy of activation (ΔH∓) values were found to be between 7.28 and 61.73 kJ mol(-1). Additionally, higher positive energy of activation (ΔG∓) values (46.82±2.01 to 94.47±2.36 kJ mol(-1)) suggested that there is an energy barrier for product formation.

  17. Low pH increases the yield of exosome isolation.

    PubMed

    Ban, Jae-Jun; Lee, Mijung; Im, Wooseok; Kim, Manho

    2015-05-22

    Exosomes are the extracellular vesicles secreted by various cells. Exosomes mediate intercellular communication by delivering a variety of molecules between cells. Cancer cell derived exosomes seem to be related with tumor progression and metastasis. Tumor microenvironment is thought to be acidic and this low pH controls exosome physiology, leading to tumor progression. Despite the importance of microenvironmental pH on exosome, most of exosome studies have been performed without regard to pH. Therefore, the difference of exosome stability and yield of isolation by different pH need to be studied. In this research, we investigated the yield of total exosomal protein and RNA after incubation in acidic, neutral and alkaline conditioned medium. Representative exosome markers were investigated by western blot after incubation of exosomes in different pH. As a result, the concentrations of exosomal protein and nucleic acid were significantly increased after incubation in the acidic medium compared with neutral medium. The higher levels of exosome markers including CD9, CD63 and HSP70 were observed after incubation in an acidic environment. On the other hand, no exosomal protein, exosomal RNA and exosome markers have been detected after incubation in an alkaline condition. In summary, our results indicate that the acidic condition is the favorable environment for existence and isolation of exosomes.

  18. Effect of CaCO3(S) nucleation modes on algae removal from alkaline water.

    PubMed

    Choi, Jin Yong; Kinney, Kerry A; Katz, Lynn E

    2016-02-29

    The role of calcite heterogeneous nucleation was studied in a particle coagulation treatment process for removing microalgae from water. Batch experiments were conducted with Scenedesmus sp. and Chlorella sp. in the presence and absence of carbonate and in the presence and absence of Mg to delineate the role of CaCO3(S) nucleation on microalgae removal. The results indicate that effective algae coagulation (e.g., up to 81 % algae removal efficiency) can be achieved via heterogeneous nucleation with CaCO3(S); however, supersaturation ratios between 120 and 200 are required to achieve at least 50% algae removal, depending on ion concentrations. Algae removal was attributed to adsorption of Ca(2+) onto the cell surface which provides nucleation sites for CaCO3(S) precipitation. Bridging of calcite particles between the algal cells led to rapid aggregation and formation of larger flocs. However, at higher supersaturation conditions, algae removal was diminished due to the dominance of homogeneous nucleation of CaCO3(S). Removal of algae in the presence of Ca(2+) and Mg(2+) required higher supersaturation values; however, the shift from heteronucleation to homonucleation with increasing supersaturation was still evident. The results suggest that water chemistry, pH, ionic strength, alkalinity and Ca(2+) concentration can be optimized for algae removal via coagulation-sedimentation.

  19. Extracellular Ca2(+)-dependent inducible alkaline phosphatase from extremely halophilic archaebacterium Haloarcula marismortui.

    PubMed Central

    Goldman, S; Hecht, K; Eisenberg, H; Mevarech, M

    1990-01-01

    When starved of inorganic phosphate, the extremely halophilic archaebacterium Haloarcula marismortui produces the enzyme alkaline phosphatase and secretes it to the medium. This inducible extracellular enzyme is a glycoprotein whose subunit molecular mass is 160 kDa, as estimated by sodium dodecyl sulfate-gel electrophoresis. The native form of the enzyme is heterogeneous and composed of multiple oligomeric forms. The enzymatic activity of the halophilic alkaline phosphatase is maximal at pH 8.5, and the enzyme is inhibited by phosphate. Unlike most alkaline phosphatases, the halobacterial enzyme requires Ca2+ and not Zn2+ ions for its activity. Both calcium ions (in the millimolar range) and NaCl (in the molar range) are required for the stability of the enzyme. Images PMID:2123861

  20. L-Phenylalanine inhibition of human alkaline phosphatases with p-nitrophenyl phosphate as substrate.

    PubMed

    Komoda, T; Hokari, S; Sonoda, M; Sakagishi, Y; Tamura, T

    1982-12-01

    With p-nitrophenyl phosphate as the substrate, there reportedly is no organ-specific inhibition of alkaline phosphatase (EC 3.1.3.1) activity by L-phenylalanine. However, we found that at pH 10.0, with p-nitrophenyl phosphate as the substrate, L-phenylalanine obviously inhibits the alkaline phosphatase isoenzyme from human placenta, whereas there is little if any inhibition of the isoenzyme from human intestine. Because of the differing effects of substrates (p-nitrophenyl phosphate and phenyl phosphate) and their enzymic products (p-nitrophenol and phenol) for L-phenylalanine action on the placental alkaline phosphatase isoenzyme, we suggest that the isoenzyme--inhibitor--substrate complex and the effect of released phosphate on L-phenylalanine inhibition of the isoenzyme activity differ from each other.

  1. Process for extracting technetium from alkaline solutions

    DOEpatents

    Moyer, Bruce A.; Sachleben, Richard A.; Bonnesen, Peter V.

    1995-01-01

    A process for extracting technetium values from an aqueous alkaline solution containing at least one alkali metal hydroxide and at least one alkali metal nitrate, the at least one alkali metal nitrate having a concentration of from about 0.1 to 6 molar. The solution is contacted with a solvent consisting of a crown ether in a diluent for a period of time sufficient to selectively extract the technetium values from the aqueous alkaline solution. The solvent containing the technetium values is separated from the aqueous alkaline solution and the technetium values are stripped from the solvent.

  2. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A.; Holmes, Michael J.

    2002-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  3. Alkaline sorbent injection for mercury control

    DOEpatents

    Madden, Deborah A.; Holmes, Michael J.

    2003-01-01

    A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

  4. Exploring crystalline-structural variations of cellulose during alkaline pretreatment for enhanced enzymatic hydrolysis.

    PubMed

    Ling, Zhe; Chen, Sheng; Zhang, Xun; Xu, Feng

    2017-01-01

    The study aimed to explore the crystallinity and crystalline structure of alkaline pretreated cellulose. The enzymatic hydrolysis followed by pretreatment was conducted for measuring the efficiency of sugar conversion. For cellulose Iβ dominated samples, alkaline pretreatment (<8wt%) caused increased cellulose crystallinity and depolymerized hemicelluloses, that were superimposed to affect the enzymatic conversion to glucose. Varying crystallite sizes and lattice spacings indicated the separation of cellulose crystals during mercerization (8-12wt% NaOH). Completion of mercerization was proved under higher alkaline concentration (14-18wt% NaOH), leading to distortion of crystalline cellulose to some extent. Cellulose II crystallinity showed a stimulative impact on enzymatic hydrolysis due to the weakened hydrophobic interactions within cellulose chains. The current study may provide innovative explanations for enhanced enzymatic digestibility of alkaline pretreated lignocellulosic materials.

  5. Effect of initial solution pH on photo-induced reductive decomposition of perfluorooctanoic acid.

    PubMed

    Qu, Yan; Zhang, Chao-Jie; Chen, Pei; Zhou, Qi; Zhang, Wei-Xian

    2014-07-01

    The effects of initial solution pH on the decomposition of perfluorooctanoic acid (PFOA) with hydrated electrons as reductant were investigated. The reductive decomposition of PFOA depends strongly on the solution pH. In the pH range of 5.0-10.0, the decomposition and defluorination rates of PFOA increased with the increase of the initial solution pH. The rate constant was 0.0295 min(-1) at pH 10.0, which was more than 49.0 times higher than that at pH 5.0. Higher pH also inhibits the generation of toxic intermediates during the PFOA decomposition. For example, the short-chain PFCAs reached a lower maximum concentration in shorter reaction time as pH increasing. The peak areas of accumulated fluorinated and iodinated hydrocarbons detected by GC/MS under acidic conditions were nearly 10-100 times more than those under alkaline conditions. In short, alkaline conditions were more favorable for photo-induced reduction of PFOA as high pH promoted the decomposition of PFOA and inhibited the accumulation of intermediate products. The concentration of hydrated electron, detected by laser flash photolysis, increased with the increase of the initial pH. This was the main reason why the decomposition of PFOA in the UV-KI system depended strongly on the initial pH.

  6. Nitric oxide production occurs after cytosolic alkalinization during stomatal closure induced by abscisic acid.

    PubMed

    Gonugunta, Vijay K; Srivastava, Nupur; Puli, Mallikarjuna R; Raghavendra, Agepati S

    2008-11-01

    Abscisic acid (ABA) raised the cytosolic pH and nitric oxide (NO) levels in guard cells while inducing stomatal closure in epidermis of Pisum sativum. Butyrate (a weak acid) reduced the cytosolic pH/NO production and prevented stomatal closure by ABA. Methylamine (a weak base) enhanced the cytosolic alkalinization and aggravated stomatal closure by ABA. The rise in guard cell pH because of ABA became noticeable after 6 min and peaked at 12 min, while NO production started at 9 min and peaked at 18 min. These results suggested that NO production was downstream of the rise in cytosolic pH. The ABA-induced increase in NO of guard cells and stomatal closure was prevented by 2-phenyl-4,4,5,5-tetramethyl imidazoline-1-oxyl 3-oxide (cPTIO, a NO scavenger) and partially by N-nitro-L-Arg-methyl ester (L-NAME, an inhibitor of NO synthase). In contrast, cPTIO or L-NAME had only a marginal effect on the pH rise induced by ABA. Ethylene glycol tetraacetic acid (EGTA, a calcium chelator) prevented ABA-induced stomatal closure while restricting cytosolic pH rise and NO production. We suggest that during ABA-induced stomatal closure, a rise in cytosolic pH is necessary for NO production. Calcium may act upstream of cytosolic alkalinization and NO production, besides its known function as a downstream component.

  7. Indicators: Conductivity

    EPA Pesticide Factsheets

    Conductivity is a measure of the ability of water to pass an electrical current. Because dissolved salts and other inorganic chemicals conduct electrical current, conductivity increases as salinity increases.

  8. Respiratory and dissimilatory nitrate-reducing communities from an extreme saline alkaline soil of the former lake Texcoco (Mexico).

    PubMed

    Alcántara-Hernández, Rocio J; Valenzuela-Encinas, César; Marsch, Rodolfo; Dendooven, Luc

    2009-01-01

    The diversity of the dissimilatory and respiratory nitrate-reducing communities was studied in two soils of the former lake Texcoco (Mexico). Genes encoding the membrane-bound nitrate reductase (narG) and the periplasmic nitrate reductase (napA) were used as functional markers. To investigate bacterial communities containing napA and narG in saline alkaline soils of the former lake Texcoco, libraries of the two sites were constructed (soil T3 with pH 11 and electrolytic conductivity in saturated extract (EC(SE)) 160 dS m(-1) and soil T1 with pH 8.5 and EC(SE) 0.8 dS m(-1)). Phylogenetic analysis of napA sequences separated the clone families into two main groups: dependent or independent of NapB. Most of napA sequences from site T1 were grouped in the NapB-dependent clade, meanwhile most of the napA sequences from the extreme soil T3 were affiliated to the NapB-independent group. For both sites, partial narG sequences were associated with representatives of the Proteobacteria, Firmicutes and Actinobacteria phyla, but the proportions of the clones were different. Our results support the concept of a specific and complex nitrate-reducing community for each soil of the former lake Texcoco.

  9. The role of urinary pH in o-phenylphenol-induced cytotoxicity and chromosomal damage in the bladders of F344 rats.

    PubMed

    Balakrishnan, S; Hasegawa, L; Eastmond, D A

    2016-04-01

    o-Phenylphenol (OPP) is a widely used fungicide and antibacterial agent that at high doses has been shown to cause bladder cancer in male F344 rats. The mechanisms underlying OPP-induced bladder carcinogenicity remain unclear but it has been proposed that a non-enzymatic pH-dependent autoxidation of phenylhydroquinone (PHQ), a primary metabolite of OPP, may be a key step in OPP-induced rat bladder carcinogenesis. To investigate this mechanism and to provide insights into the potential human health relevance of OPP-induced cancer, a series of in vitro and in vivo experiments were conducted. In human lymphoblastoid TK-6 cells and rat bladder epithelial NBT-II cells, strong increases in cytotoxicity were seen at a constant concentration of PHQ by increasing the buffer pH as well as by increasing concentrations of PHQ at a constant pH. In in vivo studies, male rats were administered OPP (4,000 and 8,000 ppm) in a diet supplemented with either 1% ammonium chloride or 3% sodium bicarbonate to produce acidic and alkaline urinary pH, respectively. Significant increases in cell proliferation as detected by 5-bromo-2'-deoxyuridine incorporation and micronucleus formation were seen in the bladder cells of OPP-treated rats with neutral or alkaline urinary pH but not in animals with the acidified urine. The results from these in vitro and in vivo studies provide support for the autoxidation hypothesis of bioactivation, and provide additional evidence that urinary pH can significantly influence the genotoxicity and carcinogenicity of this important agent.

  10. Variation of ocean pH in the Indonesia waters

    NASA Astrophysics Data System (ADS)

    Putri, Mutiara Rachmat; Setiawan, Agus; Safitri, Mediana

    2015-09-01

    The variation of ocean acidity (pH) in the Indonesia waters is strongly influenced by monsoon. Since the climate change tends to potentially change monsoonal variation over the Indonesian region, it will give also implication to the ocean pH variation. Moreover, changes of ocean pH will give effects to the marine lifes and their environment. In order to investigate this issue, we tried to calculate monthly variation of sea surface pH in the Indonesia waters based on monthly average temperature and salinity over past 18 years data. Temperature and salinity data used in this study were taken from the hydrodynamic model of Hamburg Shelf Ocean Model (HAMSOM), while alkalinity and dissolved inorganic carbon (DIC) were from World Ocean Atlas 2009 (WOA 2009). Algorithm from Ocean Carbon Model Intercomparison Project-version.3 (OCMIP-3) was used to calculate the pH. The estimation results indicate that pH variation in the Indonesia waters changes insignificantly over 18 years. El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) contribute to physical changes of seawater, but did not affect the pH significantly. The average pH of seawater is higher during northwest monsoon than during southeast monsoon.

  11. Bacterial Diversity in a Nonsaline Alkaline Environment: Heterotrophic Aerobic Populations

    PubMed Central

    Tiago, Igor; Chung, Ana Paula; Veríssimo, António

    2004-01-01

    Heterotrophic populations were isolated and characterized from an alkaline groundwater environment generated by active serpentinization, which results in a Ca(OH)2-enriched, extremely diluted groundwater with pH 11.4. One hundred eighty-five strains were isolated in different media at different pH values during two sampling periods. To assess the degree of diversity present in the environment and to select representative strains for further characterization of the populations, we screened the isolates by using random amplified polymorphic DNA-PCR profiles and grouped them based on similarities determined by fatty acid methyl ester analysis. Phenotypic characterization, determinations of G+C content, phylogenetic analyses by direct sequencing of 16S rRNA genes, and determinations of pH tolerance were performed with the selected isolates. Although 38 different populations were identified and characterized, the vast majority of the isolates were gram positive with high G+C contents and were affiliated with three distinct groups, namely, strains closely related to the species Dietzia natrolimnae (32% of the isolates), to Frigoribacterium/Clavibacter lineages (29% of the isolates), and to the type strain of Microbacterium kitamiense (20% of the isolates). Other isolates were phylogenetically related to strains of the genera Agrococcus, Leifsonia, Kytococcus, Janibacter, Kocuria, Rothia, Nesterenkonia, Citrococcus, Micrococcus, Actinomyces, Rhodococcus, Bacillus, and Staphylococcus. Only five isolates were gram negative: one was related to the Sphingobacteria lineage and the other four were related to the α-Proteobacteria lineage. Despite the pH of the environment, the vast majority of the populations were alkali tolerant, and only two strains were able to grow at pH 11. PMID:15574939

  12. Silicon improves maize photosynthesis in saline-alkaline soils.

    PubMed

    Xie, Zhiming; Song, Ri; Shao, Hongbo; Song, Fengbin; Xu, Hongwen; Lu, Yan

    2015-01-01

    The research aimed to determine the effects of Si application on photosynthetic characteristics of maize on saline-alkaline soil, including photosynthetic rate (P n ), stomatal conductance (g s ), transpiration rate (E), and intercellular CO2 concentration (C i ) of maize in the field with five levels (0, 45, 90, 150, and 225 kg · ha(-1)) of Si supplying. Experimental results showed that the values of P n, g s, and C i of maize were significantly enhanced while the values of E of maize were dramatically decreased by certain doses of silicon fertilizers, which meant that Si application with proper doses significantly increased photosynthetic efficiency of maize in different growth stages under stressing environment of saline-alkaline soil. The optimal dose of Si application in this experiment was 150 kg · ha(-1) Si. It indicated that increase in maize photosynthesis under saline-alkaline stress took place by Si application with proper doses, which is helpful to improve growth and yield of maize.

  13. Silicon Improves Maize Photosynthesis in Saline-Alkaline Soils

    PubMed Central

    Xie, Zhiming; Song, Ri; Shao, Hongbo; Song, Fengbin; Xu, Hongwen; Lu, Yan

    2015-01-01

    The research aimed to determine the effects of Si application on photosynthetic characteristics of maize on saline-alkaline soil, including photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (E), and intercellular CO2 concentration (Ci) of maize in the field with five levels (0, 45, 90, 150, and 225 kg·ha−1) of Si supplying. Experimental results showed that the values of Pn, gs, and Ci of maize were significantly enhanced while the values of E of maize were dramatically decreased by certain doses of silicon fertilizers, which meant that Si application with proper doses significantly increased photosynthetic efficiency of maize in different growth stages under stressing environment of saline-alkaline soil. The optimal dose of Si application in this experiment was 150 kg·ha−1 Si. It indicated that increase in maize photosynthesis under saline-alkaline stress took place by Si application with proper doses, which is helpful to improve growth and yield of maize. PMID:25629083

  14. Alkaline stress and iron deficiency regulate iron uptake and riboflavin synthesis gene expression differently in root and leaf tissue: implications for iron deficiency chlorosis

    PubMed Central

    Hsieh, En-Jung; Waters, Brian M.

    2016-01-01

    Iron (Fe) is an essential mineral that has low solubility in alkaline soils, where its deficiency results in chlorosis. Whether low Fe supply and alkaline pH stress are equivalent is unclear, as they have not been treated as separate variables in molecular physiological studies. Additionally, molecular responses to these stresses have not been studied in leaf and root tissues simultaneously. We tested how plants with the Strategy I Fe uptake system respond to Fe deficiency at mildly acidic and alkaline pH by measuring root ferric chelate reductase (FCR) activity and expression of selected Fe uptake genes and riboflavin synthesis genes. Alkaline pH increased cucumber (Cucumis sativus L.) root FCR activity at full Fe supply, but alkaline stress abolished FCR response to low Fe supply. Alkaline pH or low Fe supply resulted in increased expression of Fe uptake genes, but riboflavin synthesis genes responded to Fe deficiency but not alkalinity. Iron deficiency increased expression of some common genes in roots and leaves, but alkaline stress blocked up-regulation of these genes in Fe-deficient leaves. In roots of the melon (Cucumis melo L.) fefe mutant, in which Fe uptake responses are blocked upstream of Fe uptake genes, alkaline stress or Fe deficiency up-regulation of certain Fe uptake and riboflavin synthesis genes was inhibited, indicating a central role for the FeFe protein. These results suggest a model implicating shoot-to-root signaling of Fe status to induce Fe uptake gene expression in roots. PMID:27605716

  15. Alkaline hydrothermal liquefaction of swine carcasses to bio-oil.

    PubMed

    Zheng, Ji-Lu; Zhu, Ming-Qiang; Wu, Hai-tang

    2015-09-01

    It is imperative that swine carcasses are disposed of safely, practically and economically. Alkaline hydrothermal liquefaction of swine carcasses to bio-oil was performed. Firstly, the effects of temperature, reaction time and pH value on the yield of each liquefaction product were determined. Secondly, liquefaction products, including bio-oil and solid residue, were characterized. Finally, the energy recovery ratio (ERR), which was defined as the energy of the resultant products compared to the energy input of the material, was investigated. Our experiment shows that reaction time had certain influence on the yield of liquefaction products, but temperature and pH value had bigger influence on the yield of liquefaction products. Yields of 62.2wt% bio-oil, having a high heating value of 32.35MJ/kg and a viscosity of 305cp, and 22wt% solid residue were realized at a liquefaction temperature of 250°C, a reaction time of 60min and a pH value of 9.0. The bio-oil contained up to hundreds of different chemical components that may be classified according to functional groups. Typical compound classes in the bio-oil were hydrocarbons, organic acids, esters, ketones and heterocyclics. The energy recovery ratio (ERR) reached 93.63%. The bio-oil is expected to contribute to fossil fuel replacement in stationary applications, including boilers and furnaces, and upgrading processes for the bio-oil may be used to obtain liquid transport fuels.

  16. Synergistic and Antagonistic Effects of Salinity and pH on Germination in Switchgrass (Panicum virgatum L.)

    PubMed Central

    Liu, Yuan; Wang, Quanzhen; Zhang, Yunwei; Cui, Jian; Chen, Guo; Xie, Bao; Wu, Chunhui; Liu, Haitao

    2014-01-01

    The effects of salt-alkaline mixed stress on switchgrass were investigated by evaluating seed germination and the proline, malondialdehyde (MDA) and soluble sugar contents in three switchgrass (Panicum virgatum L.) cultivars in order to identify which can be successfully produced on marginal lands affected by salt-alkaline mixed stress. The experimental conditions consisted of four levels of salinity (10, 60, 110 and 160 mM) and four pH levels (7.1, 8.3, 9.5 and 10.7). The effects of salt-alkaline mixed stress with equivalent coupling of the salinity and pH level on the switchgrass were explored via model analyses. Switchgrass was capable of germinating and surviving well in all treatments under low-alkaline pH (pH≤8.3), regardless of the salinity. However, seed germination and seedling growth were sharply reduced at higher pH values in conjunction with salinity. The salinity and pH had synergetic effects on the germination percentage, germination index, plumular length and the soluble sugar and proline contents in switchgrass. However, these two factors exhibited antagonistic effects on the radicular length of switchgrass. The combined effects of salinity and pH and the interactions between them should be considered when evaluating the strength of salt-alkaline mixed stress. PMID:24454834

  17. PhD Students' Work Conditions and Study Environment in University- and Industry-Based PhD Programmes

    ERIC Educational Resources Information Center

    Kolmos, A.; Kofoed, L. B.; Du, X. Y.

    2008-01-01

    During the last 10 years, new models of funding and training PhD students have been established in Denmark in order to integrate industry into the entire PhD education. Several programmes have been conducted where it is possible to co-finance PhD scholarships or to become an employee as an industrial PhD in a company. An important question is what…

  18. Alkaline tolerant dextranase from streptomyces anulatus

    DOEpatents

    Decker, Stephen R.; Adney, William S.; Vinzant, Todd B.; Himmel, Michael E.

    2003-01-01

    A process for production of an alkaline tolerant dextranase enzyme comprises culturing a dextran-producing microorganism Streptomyces anulatus having accession no. ATCC PTA-3866 to produce an alkaline tolerant dextranase, Dex 1 wherein the protein in said enzyme is characterized by a MW of 63.3 kDa and Dex 2 wherein its protein is characterized by a MW of 81.8 kDa.

  19. phoD Alkaline Phosphatase Gene Diversity in Soil

    PubMed Central

    Kertesz, Michael A.; Bünemann, Else K.

    2015-01-01

    Phosphatase enzymes are responsible for much of the recycling of organic phosphorus in soils. The PhoD alkaline phosphatase takes part in this process by hydrolyzing a range of organic phosphoesters. We analyzed the taxonomic and environmental distribution of phoD genes using whole-genome and metagenome databases. phoD alkaline phosphatase was found to be spread across 20 bacterial phyla and was ubiquitous in the environment, with the greatest abundance in soil. To study the great diversity of phoD, we developed a new set of primers which targets phoD genes in soil. The primer set was validated by 454 sequencing of six soils collected from two continents with different climates and soil properties and was compared to previously published primers. Up to 685 different phoD operational taxonomic units were found in each soil, which was 7 times higher than with previously published primers. The new primers amplified sequences belonging to 13 phyla, including 71 families. The most prevalent phoD genes identified in these soils were affiliated with the orders Actinomycetales (13 to 35%), Bacillales (1 to 29%), Gloeobacterales (1 to 18%), Rhizobiales (18 to 27%), and Pseudomonadales (0 to 22%). The primers also amplified phoD genes from additional orders, including Burkholderiales, Caulobacterales, Deinococcales, Planctomycetales, and Xanthomonadales, which represented the major differences in phoD composition between samples, highlighting the singularity of each community. Additionally, the phoD bacterial community structure was strongly related to soil pH, which varied between 4.2 and 6.8. These primers reveal the diversity of phoD in soil and represent a valuable tool for the study of phoD alkaline phosphatase in environmental samples. PMID:26253682

  20. Culture of osteogenic cells from human alveolar bone: a useful source of alkaline phosphatase.

    PubMed

    Simão, Ana Maria S; Beloti, Marcio M; Rosa, Adalberto L; de Oliveira, Paulo T; Granjeiro, José Mauro; Pizauro, João M; Ciancaglini, Pietro

    2007-11-01

    The aim of this study was to obtain membrane-bound alkaline phosphatase from osteoblastic-like cells of human alveolar bone. Cells were obtained by enzymatic digestion and maintained in primary culture in osteogenic medium until subconfluence. First passage cells were cultured in the same medium and at 7, 14, and 21 days, total protein content, collagen content, and alkaline phosphatase activity were evaluated. Bone-like nodule formation was evaluated at 21 days. Cells in primary culture at day 14 were washed with Tris-HCl buffer, and used to extract the membrane-bound alkaline phosphatase. Cells expressed osteoblastic phenotype. The apparent optimum pH for PNPP hydrolysis by the enzyme was pH 10.0. This enzyme also hydrolyzes ATP, ADP, fructose-1-phosphate, fructose-6-phosphate, pyrophosphate and beta-glycerophosphate. PNPPase activity was reduced by typical inhibitors of alkaline phosphatase. SDS-PAGE of membrane fraction showed a single band with activity of approximately 120 kDa that could be solubilized by phospholipase C or Polidocanol.

  1. Surfactant-enhanced alkaline flooding field project. Annual report, Revision

    SciTech Connect

    French, T.R.

    1991-10-01

    The Tucker sand of Helper (KS) field is a candidate for surfactant-enhanced alkaline flooding. The geology of the Helper site is typical of many DOE Class I reservoirs. The Tucker sand of Helper field was deposited in a fluvial dominated deltaic environment. Helper oil can be mobilized with either chemical system 2 or chemical system 3, as described in this report. Oil fields in the Gulf Coast region are also good candidates for surfactant-enhanced alkaline flooding. The results from laboratory tests conducted in Berea sandstone cores with oil brine from Helper (KS) field are encouraging. The crude oil is viscous and non-acidic and, yet, was mobilized by the chemical formulations described in this report. Significant amounts of the oil were mobilized under simulated reservoir conditions. The results in Berea sandstone cores were encouraging and should be verified by tests with field core. Consumption of alkali, measured with field core, was very low. Surfactant loss appeared to be acceptable. Despite the good potential for mobilization of Helper oil, certain reservoir characteristics such as low permeability, compartmentalization, and shallow depth place constraints on applications of any chemical system in the Tucker sand. These constraints are typical of many DOE Class I reservoirs. Although Hepler field is not a perfect reservoir in which to apply surfactant- enhanced alkaline flooding, Hepler oil is particularly amenable to mobilization by surfactant-enhanced alkaline systems. A field test is recommended, dependent upon final evaluation of well logs and cores from the proposed pilot area. 14 refs., 21 figs., 10 tabs.

  2. Surfactant-enhanced alkaline flooding for light oil recovery. Quarterly report, April 1, 1995--June 30, 1995

    SciTech Connect

    Wasan, D.T.

    1995-09-01

    The overall objective of this project is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultra-low tension. In addition, the novel concept of pH gradient design to optimize flood water conditions will be tested.

  3. Alkaline Water and Longevity: A Murine Study

    PubMed Central

    Magro, Massimiliano; Corain, Livio; Ferro, Silvia; Baratella, Davide; Bonaiuto, Emanuela; Terzo, Milo; Corraducci, Vittorino; Salmaso, Luigi; Vianello, Fabio

    2016-01-01

    The biological effect of alkaline water consumption is object of controversy. The present paper presents a 3-year survival study on a population of 150 mice, and the data were analyzed with accelerated failure time (AFT) model. Starting from the second year of life, nonparametric survival plots suggest that mice watered with alkaline water showed a better survival than control mice. Interestingly, statistical analysis revealed that alkaline water provides higher longevity in terms of “deceleration aging factor” as it increases the survival functions when compared with control group; namely, animals belonging to the population treated with alkaline water resulted in a longer lifespan. Histological examination of mice kidneys, intestine, heart, liver, and brain revealed that no significant differences emerged among the three groups indicating that no specific pathology resulted correlated with the consumption of alkaline water. These results provide an informative and quantitative summary of survival data as a function of watering with alkaline water of long-lived mouse models. PMID:27340414

  4. Performed surfactant-optimized aqueous alkaline flood

    SciTech Connect

    Thigpen, D.R.; Lawson, J.B.; Nelson, R.C.

    1991-11-26

    This paper describes improvement in a process for recovering oil from an acidic oil reservoir by injecting an aqueous alkaline solution comprising water, sodium chloride, and alkaline material for reacting with the reservoir oil forming a petroleum acid soap to form an in-situ surfactant system. The improvement comprises: selecting a preformed cosurfactant which is soluble in both the aqueous solution and the reservoir oil and has a solubility ratio which is grater than the solubility ratio of the petroleum acid soap where the solubility ratio is the ratio of solubility in the aqueous alkaline solution to the solubility in the reservoir oil; combining with the alkaline solution an amount of the preformed cosurfactant which will result in the in-situ surfacant system having a salinity about equal to a salinity which results in minimal interfacial tension between the oil in the reservoir and the in-situ surfactant system at reservoir temperature, wherein the amount of the preformed cosurfactant is about 0.3 percent by weight in the aqueous alkaline solution; and injecting the cosurfactant-aqueous alkaline solution mixture into the reservoir to displace oil toward a fluid production location.

  5. Monitoring, field experiments, and geochemical modeling of Fe(II) oxidation kinetics in a stream dominated by net-alkaline coal-mine drainage, Pennsylvania, USA

    USGS Publications Warehouse

    Cravotta, Charles A.

    2015-01-01

    Watershed-scale monitoring, field aeration experiments, and geochemical equilibrium and kinetic modeling were conducted to evaluate interdependent changes in pH, dissolved CO2, O2, and Fe(II) concentrations that typically take place downstream of net-alkaline, circumneutral coal-mine drainage (CMD) outfalls and during aerobic treatment of such CMD. The kinetic modeling approach, using PHREEQC, accurately simulates observed variations in pH, Fe(II) oxidation, alkalinity consumption, and associated dissolved gas concentrations during transport downstream of the CMD outfalls (natural attenuation) and during 6-h batch aeration tests on the CMD using bubble diffusers (enhanced attenuation). The batch aeration experiments demonstrated that aeration promoted CO2 outgassing, thereby increasing pH and the rate of Fe(II) oxidation. The rate of Fe(II) oxidation was accurately estimated by the abiotic homogeneous oxidation rate law −d[Fe(II)]/dt = k1·[O2]·[H+]−2·[Fe(II)] that indicates an increase in pH by 1 unit at pH 5–8 and at constant dissolved O2 (DO) concentration results in a 100-fold increase in the rate of Fe(II) oxidation. Adjusting for sample temperature, a narrow range of values for the apparent homogeneous Fe(II) oxidation rate constant (k1′) of 0.5–1.7 times the reference value of k1 = 3 × 10−12 mol/L/min (for pH 5–8 and 20 °C), reported by Stumm and Morgan (1996), was indicated by the calibrated models for the 5-km stream reach below the CMD outfalls and the aerated CMD. The rates of CO2 outgassing and O2ingassing in the model were estimated with first-order asymptotic functions, whereby the driving force is the gradient of the dissolved gas concentration relative to equilibrium with the ambient atmosphere. Although the progressive increase in DO concentration to saturation could be accurately modeled as a kinetic function for the conditions evaluated, the simulation of DO as an instantaneous equilibrium process did not affect the

  6. Automatic online buffer capacity (alkalinity) measurement of wastewater using an electrochemical cell.

    PubMed

    Cheng, Liang; Charles, Wipa; Cord-Ruwisch, Ralf

    2016-10-01

    The use of an automatic online electrochemical cell (EC) for measuring the buffer capacity of wastewater is presented. pH titration curves of different solutions (NaHCO3, Na2HPO4, real municipal wastewater, and anaerobic digester liquid) were obtained by conventional chemical titration and compared to the online EC measurements. The results show that the pH titration curves from the EC were comparable to that of the conventional chemical titration. The results show a linear relationship between the response of the online EC detection system and the titrimetric partial alkalinity and total alkalinity of all tested samples. This suggests that an EC can be used as a simple online titration device for monitoring the buffer capacity of different industrial processes including wastewater treatment and anaerobic digestion processes.

  7. Prebiotic Synthesis of Glycine from Ethanolamine in Simulated Archean Alkaline Hydrothermal Vents

    NASA Astrophysics Data System (ADS)

    Zhang, Xianlong; Tian, Ge; Gao, Jing; Han, Mei; Su, Rui; Wang, Yanxiang; Feng, Shouhua

    2016-09-01

    Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. In recent years, a novel hydrothermal system in Archean subseafloor has been proposed. In this model, highly alkaline and high temperature hydrothermal fluids were generated in basalt-hosted hydrothermal vents, where H2 and CO2 could be abundantly provided. These extreme conditions could have played an irreplaceable role in the early evolution of life. Nevertheless, sufficient information has not yet been obtained for the abiotic synthesis of amino acids, which are indispensable components of life, at high temperature and alkaline condition. This study aims to propose a new method for the synthesis of glycine in simulated Archean submarine alkaline vent systems. We investigated the formation of glycine from ethanolamine under conditions of high temperature (80-160 °C) and highly alkaline solutions (pH = 9.70). Experiments were performed in an anaerobic environment under mild pressure (0.1-8.0 MPa) at the same time. The results suggested that the formation of glycine from ethanolamine occurred rapidly and efficiently in the presence of metal powders, and was favored by high temperatures and high pressures. The experiment provides a new pathway for prebiotic glycine formation and points out the phenomenal influence of high-temperature alkaline hydrothermal vents in origin of life in the early ocean.

  8. Influence of pH on the toxicity of ammonia to Chironomus tentans and Lumbriculus variegatus

    SciTech Connect

    Schubauer-Berigan, M.K.; Monson, P.D.; West, C.W.; Ankley, G.T.

    1995-04-01

    The US Environmental Protection Agency water-quality criteria establish permissible levels of ammonia in the nation`s fresh waters. These criteria are based on accumulated research suggesting that, for most aquatic species (primarily fishes), the toxicity of un-ionized ammonia predominates over that of the ammonium ion. The development of a sediment-quality criterion for ammonia requires evaluation of the relative toxicity of the two ammonia forms to benthic and epibenthic macroinvertebrates to determine whether the water-quality toxicity model can be applied to sediments. Flow-through ammonia toxicity tests were conducted over 10 d with the oligochaete Lumbriculus variegatus and the larval midge Chironomus tentans at four pH values (6.3, 7.2, 7.8, and 8.6) using a unique pH control system. Total ammonia was more toxic at elevated than at low pH to both species, suggesting that un-ionized ammonia (more prevalent at high pH) is important in determining the toxicity of ammonia to these two species. Hardness or alkalinity differences in the range of 30 to 200 mg/kg (as CaCO{sub 3}) did not appear to affect the toxicity of ammonia to the two species in separate 4-d tests. Based on results of the 10-d tests, the joint toxicity/pH model that establishes the water-quality criterion value for ammonia appears to be sufficiently protective of L. variegatus and C. tentans, by factors of at least 3 and 10, respectively. However, this study did not address potential differences in exposure of benthic organisms to ammonia in sediments vs. that in the water column; nor were the chronic effects of ammonia on these species measured in this study.

  9. Comparing alkaline and thermal disintegration characteristics for mechanically dewatered sludge.

    PubMed

    Tunçal, Tolga

    2011-10-01

    Thermal drying is one of the advanced technologies ultimately providing an alternative method of sludge disposal. In this study, the drying kinetics of mechanically dewatered sludge (MDS) after alkaline and thermal disintegration have been studied. In addition, the effect of total organic carbon (TOC) on specific resistance to filtration and sludge bound water content were also investigated on freshly collected sludge samples. The combined effect of pH and TOC on the thermal sludge drying rate for MDS was modelled using the two-factorial experimental design method. Statistical assessment of the obtained results proposed that sludge drying potential has increased exponentially for both increasing temperature and lime dosage. Execution of curve fitting algorithms also implied that drying profiles for raw and alkaline-disintegrated sludge were well fitted to the Henderson and Pabis model. The activation energy of MDS decreased from 28.716 to 11.390 kJ mol(-1) after disintegration. Consequently, the unit power requirement for thermal drying decreased remarkably from 706 to 281 W g(-1) H2O.

  10. Alkaline peroxide mechanical pulping of wheat straw with enzyme treatment.

    PubMed

    Zhao, Jian; Li, Xuezhi; Qu, Yinbo; Gao, Peiji

    2004-01-01

    Alkaline peroxide mechanical pulping (APMP) of wheat straw with enzyme treatment was studied. Instead of direct enzyme pretreatment on wheat straw, an alternative treatment method was used, in which coarse pulps from refiner defibrated wheat straw rather than wheat straw were pretreated with a crude enzyme containing mainly xylanase, then impregnated with alkaline H2O2 solution and further refined. The optimum conditions of enzyme treatment were xylanase dosage of 10-15 IU/g of oven-dried wheat straw, 90 min, 50-60 degrees C, pulp consistency of 5-10%, and initial pH of 5.0, and those for chemical impregnation were 6% NaOH, 70-80 degrees C, 60-90 min, and 4 to 5% H2O2. Enzyme treatment improved pulpability of wheat straw by the APMP process, and final pulp quality such as brightness, breaking length, and burst index of pulp. Pulp from the APMP process with enzyme treatment could be bleached to a brightness of 70.5% ISO by two-stage H2O2 bleaching sequence with only 4% H2O2, and breaking length of the bleach pulp reached 4470 m

  11. Transpassive electrodissolution of depleted uranium in alkaline electrolytes

    SciTech Connect

    Weisbrod, K.R.; Schake, A.R.; Morgan, A.N.; Purdy, G.M.; Martinez, H.E.; Nelson, T.O.

    1998-03-01

    To aid in removal of oralloy from the nuclear weapons stockpile, scientists at the Los Alamos National Laboratory Plutonium Facility are decontaminating oralloy parts by electrodissolution in neutral to alkaline electrolytes composed of sodium nitrate and sodium sulfate. To improve the process, electrodissolution experiments were performed with depleted uranium to understand the effects of various operating parameters. Sufficient precipitate was also produced to evaluate the feasibility of using ultrafiltration to separate the uranium oxide precipitates from the electrolyte before it enters the decontamination fixture. In preparation for the experiments, a potential-pH diagram for uranium was constructed from thermodynamic data for fully hydrated species. Electrodissolution in unstirred solutions showed that uranium dissolution forms two layers, an acidic bottom layer rich in uranium and an alkaline upper layer. Under stirred conditions results are consistent with the formation of a yellow precipitate of composition UO{sub 3}{center_dot}2H{sub 2}O, a six electron process. Amperometric experiments showed that current efficiency remained near 100% over a wide range of electrolytes, electrolyte concentrations, pH, and stirring conditions.

  12. [Effect of different environmental factors on the activities of digestive enzymes and alkaline phosphatase of Macrobrochium nipponense].

    PubMed

    Wang, Weina; Sun, Ruyong; Wang, Anli; Bao, Lei; Wang, Peng

    2002-09-01

    The activities of digestive enzymes and alkaline phosphatase from the hepatopancreas of Macrobrochium nipponense were determined under different environmental factors (calcium concentrations 20 mg.L-1, 35 mg.L-1, 60 mg.L-1, 80 mg.L-1, 150 mg.L-1; salinity 7@1000, 14@1000, pH 7.6, 8.8, 9.8). The results showed that higher Ca2+ concentration could enhance the pepsin activity, but inhibit the trysin-like activity in hepatopancreas of M. nipponense. The activities of pepsin, trysin-like, alkaline phosphatase in hepatopancreas of M. nipponense were higher under salinity of 14@1000 than under salinity of 7@1000 and 20@1000. It showed that the activities of digestive enzymes and alkaline phosphatase of shrimp increased gradually with increasing pH value from 7.6 to 9.8.

  13. Purification and characterization of an alkaline protease from Acetes chinensis

    NASA Astrophysics Data System (ADS)

    Xu, Jiachao; Liu, Xin; Li, Zhaojie; Xu, Jie; Xue, Changhu; Gao, Xin

    2005-07-01

    An alkaline protease from Acetes chinensis was purified and characterized in this study. The steps of purification include ammonium sulfate precipitation, ion-exchange chromatography with Q-sepharose Fast Flow, gel filtration chromatography with S300 and the second ion-exchange chromatography with Q-sepharose Fast Flow. The protease was isolated and purified, which was present and active on protein substrates (azocasein and casein). The specific protease activity was 17.15 folds and the recovery was 4.67. The molecular weight of the protease was estimated at 23.2 kD by SDS-PAGE. With azocasein as the susbstrate, the optimal temperature was 55°C and the optimal pH value was 5.5. Ion Ca2+ could enhance the proteolytic activity of the protease, while Cu2+, EDTA and PMSF could inhibit its activity.

  14. Recent developments on IME-alkaline water electrolysis

    NASA Astrophysics Data System (ADS)

    Vandenborre, H.; Baetsle, L. H.; Hebel, W.; Leysen, R.; Nackaerts, H.; Spaepen, G.

    Demonstration on a laboratory scale is reported for the substitution of the conventional asbestos diaphragm in alkaline water electrolysis processes by thin sheets of polyantimonic acid and polysulfone. The membranes investigated withstand concentrated KOH solutions at up to 120 C, and have the necessary ion-conducting and gas-separating properties. It was also found that, by increasing the amount of polyantimonic acid in the membrane, electrolyte concentration can be lowered from 30 percent to 5 percent (by weight) without major effect on the cell voltage.

  15. Peribulbar anesthesia for cataract surgery: Effect of lidocaine warming and alkalinization on injection pain, motor and sensory nerve blockade

    PubMed Central

    Jaichandran, Venkatakrishnan; Vijaya, Lingam; George, Ronnie Jacob; InderMohan, Bhanulakshmi

    2010-01-01

    Aim: To compare self-reported pain and efficacy of warmed, alkalinized, and warmed alkalinized lidocaine with plain 2% lidocaine at room temperature for peribulbar anesthesia in cataract surgery. Materials and Methods: Through a prospective, single-blinded, randomized, controlled clinical trial 200 patients were divided into four groups. They received either lidocaine at operating room temperature 18°C, control group (Group C), lidocaine warmed to 37°C (Group W), lidocaine alkalinized to a pH of 7.09 ± 0.10 (Group B) or lidocaine at 37°C alkalinized to a pH of 6.94 ± 0.05 (Group WB). All solutions contained Inj. Hyaluronidase 50 IU/ml. Pain was assessed using a 10-cm visual analog score scale. Time of onset of sensory and motor blockade and time to onset of postoperative pain were recorded by a blinded observer. Results: Mean pain score was significantly lower in Group B and WB compared with Group C (P < 0.001). Onset of analgesia was delayed in Group C compared with Group B (P = 0.021) and WB (P < 0.001). Mean time taken for the onset of complete akinesia and supplementation required for the block was significantly lower in Group B. Time of onset of pain after operation was significantly earlier in Group W compared with Group C (P = 0.036). Conclusion: Alkalinized lidocaine with or without warming produced less pain than lidocaine injected at room temperature. Alkalinization enhances the effect of warming for sensory nerve blockade, but warming does not enhance alkalinization, in fact it reduces the efficacy of alkalinized solution for blocking the motor nerves in the eye. PMID:20195031

  16. pH Basics

    ERIC Educational Resources Information Center

    Lunelli, Bruno; Scagnolari, Francesco

    2009-01-01

    The exposition of the pervasive concept of pH, of its foundations and implementation as a meaningful quantitative measurement, in nonspecialist university texts is often not easy to follow because too many of its theoretical and operative underpinnings are neglected. To help the inquiring student we provide a concise introduction to the depth just…

  17. pH optrode

    DOEpatents

    Northrup, M. Allen; Langry, Kevin C.

    1993-01-01

    A process is provided for forming a long-lasting, stable, pH-sensitive dye-acrylamide copolymer useful as a pH-sensitive material for use in an optrode or other device sensitive to pH. An optrode may be made by mechanically attaching the copolymer to a sensing device such as an optical fiber.

  18. Ph.D. shortage

    NASA Astrophysics Data System (ADS)

    The late 1990s will see a shortage of Ph.D. graduates, according to the Association of American Universities, Washington, D.C. AAU's new comprehensive study, “The Ph.D. Shortage: The Federal Role,” reports that competition for new Ph.D.s is already intense and can only intensify because demand is greater than supply in both academic and nonacademic markets.Doctoral education plays an increasingly important role in U.S. research and development programs. Students have a pivotal part in doing research and enriching it with new ideas. The AAU report says that graduate students are “major determinants of the creativity and productivity of U.S. academic research, the source of more than 50% of the nation's basic research.’ The market for doctoral education extends beyond the university. In 1985, about 43% of all Ph.D.s employed in this country were working outside higher education; the demand for doctorate recipients in nonacademic sectors continues to grow.

  19. Alkaline assisted thermal oil recovery: Kinetic and displacement studies

    SciTech Connect

    Saneie, S.; Yortsos, Y.C.

    1993-06-01

    This report deals with two major issues of chemical assisted flooding - the interaction of caustic, one of the proposed additives to steam flood, with the reservoir rock, and the displacement of oil by a chemical flood at elevated temperatures. A mathematical model simulating the kinetics of silica dissolution and hydroxyl ion consumption in a typical alkaline flooding environment is first developed. The model is based on the premise that dissolution occurs via hydrolysis of active sites through the formation of an intermediate complex, which is in equilibrium with the silicic acid in solution. Both static (batch) and dynamic (core flood) processes are simulated to examine the sensitivity of caustic consumption and silica dissolution to process parameters, and to determine rates of propagation of pH values. The model presented provides a quantitative description of the quartz-alkali interaction in terms of pH, salinity, ion exchange properties, temperature and contact time, which are of significant importance in the design of soluble silicate flooding processes. The modeling of an adiabatic hot waterflood assisted by the simultaneous injection of a chemical additive is next presented. The model is also applicable to the hot alkaline flooding under conditions of negligible adsorption of the generated anionic surfactant and of hydroxide adsorption being Langmuirian. The theory of generalized simple waves (coherence ) is used to develop solutions for the temperature, concentration, and oil saturation profiles, as well as the oil recovery curves. It is shown that, for Langmuir adsorption kinetics, the chemical resides in the heated region of the reservoir if its injection concentration is below a critical value, and in the unheated region if its concentration exceeds this critical value. Results for a chemical slug injection in a tertiary recovery process indicate recovery performance is maximized when chemical resides in the heated region of the reservior.

  20. Cloning and Overexpression of Alkaline Phosphatase PhoK from Sphingomonas sp. Strain BSAR-1 for Bioprecipitation of Uranium from Alkaline Solutions▿

    PubMed Central

    Nilgiriwala, Kayzad S.; Alahari, Anuradha; Rao, Amara Sambasiva; Apte, Shree Kumar

    2008-01-01

    Cells of Sphingomonas sp. strain BSAR-1 constitutively expressed an alkaline phosphatase, which was also secreted in the extracellular medium. A null mutant lacking this alkaline phosphatase activity was isolated by Tn5 random mutagenesis. The corresponding gene, designated phoK, was cloned and overexpressed in Escherichia coli strain BL21(DE3). The resultant E. coli strain EK4 overexpressed cellular activity 55 times higher and secreted extracellular PhoK activity 13 times higher than did BSAR-1. The recombinant strain very rapidly precipitated >90% of input uranium in less than 2 h from alkaline solutions (pH, 9 ± 0.2) containing 0.5 to 5 mM of uranyl carbonate, compared to BSAR-1, which precipitated uranium in >7 h. In both strains BSAR-1 and EK4, precipitated uranium remained cell bound. The EK4 cells exhibited a much higher loading capacity of 3.8 g U/g dry weight in <2 h compared to only 1.5 g U/g dry weight in >7 h in BSAR-1. The data demonstrate the potential utility of genetically engineering PhoK for the bioprecipitation of uranium from alkaline solutions. PMID:18641147

  1. An improved method for analysis of hydroxide and carbonate in alkaline electrolytes containing zinc

    NASA Technical Reports Server (NTRS)

    Reid, M. A.

    1978-01-01

    A simplified method for titration of carbonate and hydroxide in alkaline battery electrolyte is presented involving a saturated KSCN solution as a complexing agent for zinc. Both hydroxide and carbonate can be determined in one titration, and the complexing reagent is readily prepared. Since the pH at the end point is shifted from 8.3 to 7.9 - 8.0, m-cresol purple or phenol red are used as indicators rather than phenolphthalein. Bromcresol green is recommended for determination of the second end point of a pH of 4.3 to 4.4.

  2. An improved method for analysis of hydroxide and carbonate in alkaline electrolytes containing zinc

    NASA Technical Reports Server (NTRS)

    Reid, M. A.

    1978-01-01

    A simplified method for titration of carbonate and hydroxide in alkaline battery electrolyte is presented involving a saturated KSCN solution as a complexing agent for zinc. Both hydroxide and carbonate can be determined in one titration, and the complexing reagent is readily prepared. Since the pH at the end point is shifted from 8.3 to 7.9-8.0, m-cresol purple or phenol red are used as indicators rather than phenolphthalein. Bromcresol green is recommended for determination of the second end point of a pH of 4.3 to 4.4.

  3. Enhanced coagulation with polyaluminum chlorides: role of pH/alkalinity and speciation.

    PubMed

    Yan, Mingquan; Wang, Dongsheng; Yu, Jianfeng; Ni, Jinren; Edwards, Marc; Qu, Jiuhui

    2008-04-01

    Enhanced coagulation is considered to be among the best available techniques (BAT) for disinfection by-product (DBP) precursor removal in water treatment. Improving existing understanding requires further consideration of nuances of chemical speciation relative to source water chemistry. In this paper, the effect of alkalinity/pH and speciation on inorganic polymer flocculants, polyaluminum chlorides (PACls) for enhanced particle and natural organic matter (NOM) removal was investigated. Three kinds of well-characterized typical source waters in China with low, moderate, and high alkalinity were selected. Performance of coagulants is controlled not only by preformed species but also by those formed in situ. At neutral and basic pH values, PACls with higher basicity (ratio of OH(-)/Al), which have more stable preformed Alb (the rapid reacted species as in ferron assay), are more efficient for turbidity and NOM removal. At slightly acidic pH, PACls with lower basicity are more efficient since more Alb can be formed in situ. Optimal NOM removal was achieved at pH 5.5-6.5 for all PACls. Basicity, speciation, and dosage of coagulant should be optimized based on raw water alkalinity to enhance the removal efficiency of NOM.

  4. Block copolymers for alkaline fuel cell membrane materials

    NASA Astrophysics Data System (ADS)

    Li, Yifan

    Alkaline fuel cells (AFCs) using anion exchange membranes (AEMs) as electrolyte have recently received considerable attention. AFCs offer some advantages over proton exchange membrane fuel cells, including the potential of non-noble metal (e.g. nickel, silver) catalyst on the cathode, which can dramatically lower the fuel cell cost. The main drawback of traditional AFCs is the use of liquid electrolyte (e.g. aqueous potassium hydroxide), which can result in the formation of carbonate precipitates by reaction with carbon dioxide. AEMs with tethered cations can overcome the precipitates formed in traditional AFCs. Our current research focuses on developing different polymer systems (blend, block, grafted, and crosslinked polymers) in order to understand alkaline fuel cell membrane in many aspects and design optimized anion exchange membranes with better alkaline stability, mechanical integrity and ionic conductivity. A number of distinct materials have been produced and characterized. A polymer blend system comprised of poly(vinylbenzyl chloride)-b-polystyrene (PVBC-b-PS) diblock copolymer, prepared by nitroxide mediated polymerization (NMP), with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) or brominated PPO was studied for conversion into a blend membrane for AEM. The formation of a miscible blend matrix improved mechanical properties while maintaining high ionic conductivity through formation of phase separated ionic domains. Using anionic polymerization, a polyethylene based block copolymer was designed where the polyethylene-based block copolymer formed bicontinuous morphological structures to enhance the hydroxide conductivity (up to 94 mS/cm at 80 °C) while excellent mechanical properties (strain up to 205%) of the polyethylene block copolymer membrane was observed. A polymer system was designed and characterized with monomethoxy polyethylene glycol (mPEG) as a hydrophilic polymer grafted through substitution of pendent benzyl chloride groups of a PVBC

  5. Leaching properties of electric arc furnace dust prior/following alkaline extraction.

    PubMed

    Orescanin, Visnja; Mikelić, Luka; Sofilić, Tahir; Rastovcan-Mioc, Alenka; Uzarević, Krunoslav; Medunić, Gordana; Elez, Loris; Lulić, Stipe

    2007-02-15

    This study was carried out to determine the appropriate treatment of electric arc furnace (EAF) dust prior to permanent disposal. The total heavy metal content as well as heavy metal leaching from EAF dust was investigated in five composite samples obtained from three Croatian and Slovenian steelworks. In order to recover zinc and reduce its leaching from the dust, all five samples were submitted to alkaline extraction with 10 M NaOH. Reduction of Cr (VI) to Cr(III) was conducted using FeSO4 x 7H2O solution. The elements Mn, Fe, Cu, Ni, and notably Zn and Pb, exhibited highest mobility during toxicity characteristic leaching procedure (TCLP). Comparing to TCLP extracts of initial EAF dust, zinc was found to be over 15 times lower and lead over 200 times lower in TCLP extracts of EAF dust processed by the alkaline leaching method. Since Cr (VI) exceeded its permissible level in the DIN 38414-S4 extracts of both initial and alkaline digested dust, its reduction to Cr (III) prior to permanent disposal is necessary. The recovery of zinc from EAF dust treated with alkaline agent ranged from 50.3% to 73.2%. According to phase analysis, recovery yield showed dependence on zincite/franklinite ratio. The results of the study indicate that permanent disposal of EAF dust require the following procedure: alkaline digestion (followed by leachate purification and alkaline zinc electrolyses), chromate reduction (if necessary), solidification of leaching residue and its testing using the leaching analyses.

  6. Hexavalent uranium diffusion into soils from concentrated acidic and alkaline solutions

    SciTech Connect

    Tokunaga, Tetsu K.; Wan, Jiamin; Pena, Jasquelin; Sutton, Stephen R.; Newville, Matthew

    2004-03-29

    Uranium contamination of soils and sediments often originates from acidic or alkaline waste sources, with diffusion being a major transport mechanism. Measurements of U(VI) diffusion from initially pH 2 and pH 11 solutions into a slightly alkaline Altamont soil and a neutral Oak Ridge soil were obtained through monitoring uptake from boundary reservoirs and from U concentration profiles within soil columns. The soils provided pH buffering, resulting in diffusion at nearly constant pH. Micro x-ray absorption near edge structure spectra confirmed that U remained in U(VI) forms in all soils. Time trends of U(VI) depletion from reservoirs, and U(VI) concentration profiles within soil columns yielded K{sub d} values consistent with those determined in batch tests at similar concentrations ({approx} 1 mM), and much lower than values for sorption at much lower concentrations (nM to {mu}M). These results show that U(VI) transport at high concentrations can be relatively fast at non-neutral pH, with negligible surface diffusion, because of weak sorption.

  7. Effects of pH or a(w) stress on growth of Listeria monocytogenes.

    PubMed

    Cheroutre-Vialette, M; Lebert, I; Hebraud, M; Labadie, J C; Lebert, A

    1998-06-30

    The growth of three strains of Listeria monocytogenes at 20 degrees C in a meat broth of different pH or water activity was investigated. At inoculation or at the beginning of the exponential phase, cells were exposed to stress by the addition of NaOH or NH4+, acetic acid, NaCl or KCl, in order to reach a pH of either 9.0 or 5.6, or an a(w) of 0.950 or 0.965, respectively. The effects of the exposure to stress on the generation and lag times of each strain were analysed by turbidity measurements for cultures in micro-titer plates. Results were confirmed by conducting the same experiments in a fermentor, except for the maximal population reached. The three strains showed similar behaviour. Cells were able to overcome the alkaline stress rapidly whereas acid and osmotic shocks induced important changes of the growth parameters. Cells exposed to acid or osmotic conditions from the time of inoculation were less affected than cells exposed at the beginning of the mid-exponential phase.

  8. Soil carbon cycle of different saline and alkaline soils under cotton fields in Tarim River Basin

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoning; Zhao, Chengyi; Stahr, Karl; Kuzyakov, Yakov

    2015-04-01

    Calcium carbonate is the most common form of carbon (C) in semiarid and arid soils. Depending on pH and salinity changes, soils can act as sink or source of atmospheric CO2 as well as contribute to C exchange between CO2 and CaCO3 leading to formation of pedogenic carbonates. However, the rates of these processes and the effects of environmental factors remains unknown. 14CO2 was used to assess carbonate recrystallization in 4 saline and alkaline soils (Aksu alkaline, Aksu saline, Yingbazar alkaline, Yingbazar saline) (EC = 0.32, 1.35, 1.72, 3.67 (1:20) mS cm-1, pH = 8.5, 8.2, 8.9, 7.9 respectively) and to trace the C exchange in the soils of the Tarim River basin depending on CO2 concentrations in soils (0.02%, 0.04%, 0.2%, 0.4% and 4%). 14C was traced in soil water and air as well as in carbonates. The highest 14C in 14CO2 (95% of the 14C input) was observed in Aksu alkaline soil and the highest 14C incorporation in CaCO3 (54%) was observed in Yingbazar saline soil. There were close negative linear relationships between initial CO2 concentrations (0.04%, 0.4% and 4%) and the 14C in Ca14CO3 and in 14CO2. The carbonate recrystallization rate increased with the CO2 concentration and were depended on the recrystalliztion period. The average carbonate recrystallization rate was highest at 4% CO2 concentration for Yingbazar saline soil (6.59×10-4 % per day) and the lowest at 0.04% CO2 concentration for Aksu alkaline soil (0.03×10-4 % per day). The carbonate recrystallization rate linearly increased with the soil EC and with 0.04% and 0.4% CO2 concentration , whereas the carbonate recrystallization rate decreased with pH. The highest CO2 concentration of 4% can 10 to 100 times shorten the full carbonate recrystallization of the remaining primary carbonates compared to lower CO2 concentrations 0.4% and 0.04% for complete (95%) recrystallization of soil carbonate. We conclude that microbial and root respiration affecting CO2 concentration in soil is the most important

  9. Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

    SciTech Connect

    Malcolm Pitts; Jie Qi; Dan Wilson; David Stewart; Bill Jones

    2005-10-01

    Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A prior fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Chromium acetate-xanthan gum rigid gels are not stable to subsequent alkaline-surfactant-polymer solution injection. Resorcinol-formaldehyde gels were stable to subsequent alkaline-surfactant-polymer solution injection. When evaluated in a dual core configuration, injected fluid flows into the core with the greatest effective permeability to the injected fluid. The same gel stability trends to subsequent

  10. Solubilization of matrix protein M1/M from virions occurs at different pH for orthomyxo- and paramyxoviruses.

    PubMed

    Zhirnov, O P

    1990-05-01

    Enveloped viruses, of which the orthomyxo- and paramyxoviruses are members, are known to be uncoated by nonionic detergents in a salt concentration-dependent manner. In this study we have shown that detergent uncoating of myxoviruses depends not only on salt concentration but also on pH. Treatment of orthomyxoviruses with Nonidet-P40 or Triton N-101 at low salt concentrations results in solubilization of surface virion glycopolypeptides in alkaline and neutral pH (9.0-6.5), but in acidic pH (6.0-5.0) the viral matrix protein M1 is also removed, and the viral ribonucleoprotein complex is released. Conversely, the paramyxovirus matrix protein M is more completely solubilized in alkaline pH (pH 9.0) than in neutral and acidic pH 7.4-5.0. The described pH-dependent differences are discussed in terms of orthomyxo- and paramyxovirus uncoating in target cells.

  11. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Allen, Philip B.

    1979-01-01

    Examines Drude's classical (1900) theory of electrical conduction, details the objections to and successes of the 1900 theory, and investigates the Quantum (1928) theory of conduction, reviewing its successes and limitations. (BT)

  12. Evaluation of metal oxide and carbonate nanoparticle stability in soybean oil: Implications for controlled release of alkalinity during subsurface remediation

    NASA Astrophysics Data System (ADS)

    Ramsburg, C. A.; Leach, O. I.; Sebik, J.; Muller, K.

    2011-12-01

    Traditional methods for adjusting groundwater pH rely on injection of aqueous solutes and therefore, amendment distribution is reliant upon aqueous phase flow and transport. This reliance can limit mixing and sustention of amendments within the treatment zone. Oil-in-water emulsions offer an alternative for amendment delivery - one that has potential to enhance control of the distribution and release of buffering agents within the subsurface. Focus here is placed on using metal oxide and carbonate nanoparticles to release alkalinity from soybean oil, a common dispersed phase within emulsions designed to support remediation activities. Batch reactor systems were employed to examine the influence of dispersed phase composition on particle stability and solubility. The stability of uncoated MgO and CaCO3 particles in unmodified soybean oil was explored in a series of sedimentation studies conducted at solid loadings of 0.05, 0.1, and 0.2% mass. Three nominal sizes of MgO particles were examined (20, 50, and 100 nm) and one CaCO3 particle size (60 nm). Results from sedimentation studies conducted over four hours suggest that the viscosity of the soybean oil imparts a kinetic stability, for all sizes of the uncoated MgO and CaCO3 nanoparticles, which is sufficient time for particle encapsulation within oil-in-water emulsions. Based upon these results, the sedimentation of the 50 nm and 100 nm MgO, and 60 nm CaCO3 particles was assessed over longer durations (≥72 hr). Results from these stability tests suggest that the 50 nm and 100 nm MgO particles have greater kinetic stability than the 60 nm CaCO3. Batch studies were also used to assess the influence of n-butanol, a co-solvent hypothesized to aid in controlling the rate of alkalinity release, on phase behavior and metal (Mg2+ and Ca2+) solubility. Phase behavior studies suggest that n-butanol has a limited region of miscibility within the soybean oil-water system. Use of n-butanol and water within this region of

  13. Influence of Urinary pH on the Pharmacokinetics of Cinoxacin in Humans and on Antibacterial Activity In Vitro

    PubMed Central

    Barbhaiya, Rashmi H.; Gerber, Andreas U.; Craig, William A.; Welling, Peter G.

    1982-01-01

    The impact of acidification and alkalinization of the urine on the pharmacokinetics of cinoxacin was examined after single 500-mg oral doses were administered to nine healthy male volunteers. Acidic and alkaline conditions were achieved by repeated oral doses of ammonium chloride or sodium bicarbonate, respectively. Plasma cinoxacin levels in all subjects were adequately described in terms of one-compartment-model kinetics with first-order absorption and elimination. Acidification and alkalinization treatment had no effect on cinoxacin absorption or distribution. The mean elimination half-life of cinoxacin in plasma was 1.1, 2.0, and 0.6 h in control subjects and with acidification and alkalinization of urine, respectively. Recovery of intact cinoxacin in samples of urine collected 0 to 36 h after cinoxacin administration represented 65% of the dose in control subjects and urine acidification and 80% of the dose with alkalinization of urine. The mean renal clearance of cinoxacin was 76, 118, and 278 ml/min with acidification, control, and alkalinization, respectively, and renal clearance was highly correlated with urinary pH. Urine concentrations of cinoxacin were significantly higher with alkalinization compared with control values during the first 4 h after drug administration. Urine cinoxacin concentrations were reduced somewhat by acidification, but these tended not to be significantly different from control values. Changes in cinoxacin elimination owing to urine pH are less pronounced in humans than in dogs. The antibacterial activity of cinoxacin against some common urinary tract pathogens was pH dependent. A four- to eightfold reduction in cinoxacin activity was generally observed at pH 8 compared with lower pH values. However, in view of the high levels of cinoxacin which are obtained in both acidic and basic urine, the impact of urine pH on cinoxacin antibacterial efficacy would be of minor clinical importance. PMID:7103450

  14. Effect of Ca2+ and K+ on the intracellular pH of an Escherichia coli L-form.

    PubMed

    Onoda, T; Oshima, A; Fukunaga, N; Nakatani, A

    1992-06-01

    The L-form NC7, derived from Escherichia coli K12, grew in a complex medium containing 0.2 M-CaCl2 as osmotic stabilizer, but not at pH values above 7.8. The cessation of growth at alkaline pH was not due to cell death. In complex media containing K+ or Na+, the L-form grew ove a wide pH range. Growth at alkaline pH was inhibited by 1 mM-amiloride, indicating that Na+/H+ antiport activity was required for growth at alkaline pH. The internal pH (pHi) of the L-form in media containing K+, Na+ or Ca2+ was constant at about 7.8 to 8.0 at external pH (pHo) values of 7.2 and 8.2. The rates of O2 consumption by intact cells, lactate oxidation by membrane vesicles from cells grown in Ca(2+)-containing medium, and cell division were all strongly repressed under alkaline conditions.

  15. Alkaline Response of a Halotolerant Alkaliphilic Halomonas Strain and Functional Diversity of Its Na+(K+)/H+ Antiporters.

    PubMed

    Cheng, Bin; Meng, Yiwei; Cui, Yanbing; Li, Chunfang; Tao, Fei; Yin, Huijia; Yang, Chunyu; Xu, Ping

    2016-12-09

    Halomonas sp. Y2 is a halotolerant alkaliphilic strain from Na(+)-rich pulp mill wastewater with high alkalinity (pH >11.0). Transcriptome analysis of this isolate revealed this strain may use various transport systems for pH homeostasis. In particular, the genes encoding four putative Na(+)/H(+) antiporters were differentially expressed upon acidic or alkaline conditions. Further evidence, from heterologous expression and mutant studies, suggested that Halomonas sp. Y2 employs its Na(+)/H(+) antiporters in a labor division way to deal with saline and alkaline environments. Ha-NhaD2 displayed robust Na(+)(Li(+)) resistance and high transport activities in Escherichia coli; a ΔHa-nhaD2 mutant exhibited growth inhibition at high Na(+)(Li(+)) concentrations at pH values of 6.2, 8.0, and 10.0, suggesting its physiological role in osmotic homeostasis. In contrast, Ha-NhaD1 showed much weaker activities in ion exporting and pH homeostasis. Ha-Mrp displayed a combination of properties similar to those of Mrp transporters from some Bacillus alkaliphiles and neutrophiles. This conferred obvious Na(+)(Li(+), K(+)) resistance in E. coli-deficient strains, as those ion transport spectra of some neutrophil Mrp antiporters. Conversely, similar to the Bacillus alkaliphiles, Ha-Mrp showed central roles in the pH homeostasis of Halomonas sp. Y2. An Ha-mrp-disrupted mutant was seriously inhibited by high concentrations of Na(+)(Li(+), K(+)) but only under alkaline conditions. Ha-NhaP was determined to be a K(+)/H(+) antiporter and shown to confer strong K(+) resistance both at acidic and alkaline stresses.

  16. Uranium removal from groundwater by natural clinoptilolite zeolite: effects of pH and initial feed concentration.

    PubMed

    Camacho, Lucy Mar; Deng, Shuguang; Parra, Ramona R

    2010-03-15

    Adsorption of uranium (VI) on a natural clinoptilolite zeolite from Sweetwater County, Wyoming was investigated. Batch experiments were conducted to study the effects of pH and initial feed concentrations on uranium removal efficiency. It was found that the clinoptilolite can neutralize both acidic and low basic water solutions through its alkalinity and ion-exchange reactions with U within the solution, and adsorption of uranium (VI) species on clinoptilolite not only depends on the pH but also the initial feed concentration. The highest uranium removal efficiency (95.6%) was obtained at initial uranium concentration of 5mg/L and pH 6.0. The Langmuir adsorption isotherm model correlates well with the uranium adsorption equilibrium data for the concentration range of 0.1-500 mg/L. From the experimental data obtained in this work, it was found that the zeolite sample investigated in this work is a mixture of clinoptilolite-Na zeolite and mineral impurities with a relatively large specific surface area (BET of 18 m(2)/g) and promising adsorption properties for uranium removal from contaminated water.

  17. Stabilization of Mercury in High pH Tank Sludges

    SciTech Connect

    Spence, R.; Barton, J.

    2003-02-24

    DOE complex contains many tank sludges contaminated with mercury. The high pH of these tank sludges typically fails to stabilize the mercury, resulting in these radioactive wastes also being characteristically hazardous or mixed waste. The traditional treatment for soluble inorganic mercury species is precipitation as insoluble mercuric sulfide. Sulfide treatment and a commercial mercury-stabilizing product were tested on surrogate sludges at various alkaline pH values. Neither the sulfide nor the commercial product stabilized the mercury sufficiently at the high pH of the tank sludges to pass the Toxicity Characteristic Leach Procedure (TCLP) treatment standards of the Resource Conservation and Recovery Act (RCRA). The commercial product also failed to stabilize the mercury in samples of the actual tank sludges.

  18. In Vitro Determination of Bicarbonate Dosage to Alkalinize Local Anesthetics to Physiologic pH

    DTIC Science & Technology

    1997-05-01

    as "an unpleasant sensory and emotional experience associated with actual damage or injury to a body tissue" (Mersky, 1986, p.SI). However, this...definition does not adequately express the unique, mutable and subjective experience that those who suffer pain encounter. Milton alludes to the...emotional experience of pain in Paradise Lost when he writes "Pain is perfect miserie, the worst of evils, and excessive, overturns all patience" (Milton

  19. Pitting Corrosion of Copper in Waters with High pH and Low Alkalinity

    EPA Science Inventory

    Localized or pitting corrosion of copper pipes used in household drinking-water plumbing is a problem for many water utilities and their customers. Extreme attack can lead to pinhole water leaks that may result in water damage, mold growth, and costly repairs. Water quality has b...

  20. Low-Temperature Alkaline pH Hydrolysis of Oxygen-Free Titan Tholins: Carbonates' Impact

    NASA Astrophysics Data System (ADS)

    Brassé, Coralie; Buch, Arnaud; Coll, Patrice; Raulin, François

    2017-01-01

    Titan, the largest moon of Saturn, is one of the key planetary objects in the field of exobiology. Its dense, nitrogen-rich atmosphere is the site of important organic chemistry. This paper focuses on the organic aerosols produced in Titan's atmosphere that play an important role in atmospheric and surface processes and in organic chemistry as it applies to exobiological interests. To produce reliable laboratory analogues of these aerosols, we developed, tested, and optimized a device for the synthesis of clean tholins. The potential chemical evolution of Titan aerosols at Titan's surface has been studied, in particular, the possible interaction between aerosols and putative ammonia-water cryomagma. Modeling of the formation of Saturn's atmosphere has permitted the characterization of a composition of salts in the subsurface ocean and cryolava. From this new and original chemical composition, a laboratory study of several hydrolyses of tholins was carried out. The results obtained show the formation of many organic compounds, among them, species identified only in the presence of salts. In addition, a list of potential precursors of these compounds was established, which could provide a database for research of the chemical composition of tholins and/or aerosols of Titan.

  1. The pH of Enceladus' ocean

    NASA Astrophysics Data System (ADS)

    Glein, Christopher R.; Baross, John A.; Waite, J. Hunter

    2015-08-01

    Saturn's moon, Enceladus, is a geologically active waterworld. The prevailing paradigm is that there is a subsurface ocean that erupts to the surface, which leads to the formation of a plume of vapor and ice above the south polar region. The chemistry of the ocean is just beginning to be understood, but is of profound geochemical and astrobiological interest. Here, we determine the pH of the ocean using a thermodynamic model of carbonate speciation. Observational data from the Cassini spacecraft are used to make a chemical model of ocean water on Enceladus. The model suggests that Enceladus' ocean is a Na-Cl-CO3 solution with an alkaline pH of ∼11-12. The dominance of aqueous NaCl is a feature that Enceladus' ocean shares with terrestrial seawater, but the ubiquity of dissolved Na2CO3 suggests that soda lakes are more analogous to the Enceladus ocean. The high pH implies that the hydroxide ion should be relatively abundant, while divalent metals should be present at low concentrations owing to buffering by carbonates and phyllosilicates on the ocean floor. Carboxyl groups in dissolved organic species would be negatively charged, while amino groups would exist predominately in the neutral form. Knowledge of the pH improves our understanding of geochemical processes in Enceladus' ocean. The high pH is interpreted to be a key consequence of serpentinization of chondritic rock, as predicted by prior geochemical reaction path models; although degassing of CO2 from the ocean may also play a role depending on the efficiency of mixing processes in the ocean. Serpentinization leads to the generation of H2, a geochemical fuel that can support both abiotic and biological synthesis of organic molecules such as those that have been detected in Enceladus' plume. Serpentinization and H2 generation should have occurred on Enceladus, like on the parent bodies of aqueously altered meteorites; but it is unknown whether these critical processes are still taking place, or if

  2. Surfactant-enhanced alkaline flooding for light oil recovery. Quarterly report, January 1--March 31, 1994

    SciTech Connect

    Wasan, D.T.

    1994-06-01

    The overall objective of this project is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultra-low tension. In addition, the novel concept of pH gradient design to optimize flood water conditions will be tested. Last quarter we investigated the phase behavior and the regions where in the middle phase occurs. The optimum phase was found to go through a maximum with pH, sodium concentration and surfactant concentration. The optimum pH is about 12.0 to 13.5, the optimum sodium concentration is about 0.513 mol/liter, and the optimum surfactant concentration is about 0.2%. The effect of surfactant type was also investigated. Petrostep B-105 was found to give the most middle phase production. This quarter, we investigated the contact angle of Long Beach oil, Adena oil, and a model oil on a solid glass surface in contact with an aqueous alkaline solution both with and without added preformed surfactant. The contact angle with Long Beach and Adena oils showed oil-wet conditions, whereas the model oil showed both oil-wet and water-wet conditions depending on the pH of the aqueous phase. The addition of surfactant to the alkaline solution resulted in making the system less oil-wet. Spreading of the oil on the glass surface was observed in all three systems investigated.

  3. Membrane-bound alkaline phosphatase from ectopic mineralization and rat bone marrow cell culture.

    PubMed

    Simão, Ana Maria S; Beloti, Márcio M; Cezarino, Rodrigo M; Rosa, Adalberto Luiz; Pizauro, João M; Ciancaglini, Pietro

    2007-04-01

    Cells from rat bone marrow exhibit the proliferation-differentiation sequence of osteoblasts, form mineralized extracellular matrix in vitro and release alkaline phosphatase into the medium. Membrane-bound alkaline phosphatase was obtained by method that is easy to reproduce, simpler and fast when compared with the method used to obtain the enzyme from rat osseous plate. The membrane-bound alkaline phosphatase from cultures of rat bone marrow cells has a MW(r) of about 120 kDa and specific PNPP activity of 1200 U/mg. The ecto-enzyme is anchored to the plasma membrane by the GPI anchor and can be released by PIPLC (selective treatment) or polidocanol (0.2 mg/mL protein and 1% (w/v) detergent). The apparent optimum pH for PNPP hydrolysis by the enzyme was pH 10. This fraction hydrolyzes ATP (240 U/mg), ADP (350 U/mg), glucose 1-phosphate (1100 U/mg), glucose 6-phosphate (340 U/mg), fructose 6-phosphate (460 U/mg), pyrophosphate (330 U/mg) and beta-glycerophosphate (600 U/mg). Cooperative effects were observed for the hydrolysis of PPi and beta-glycerophosphate. PNPPase activity was inhibited by 0.1 mM vanadate (46%), 0.1 mM ZnCl2 (68%), 1 mM levamisole (66%), 1 mM arsenate (44%), 10 mM phosphate (21%) and 1 mM theophylline (72%). We report the biochemical characterization of membrane-bound alkaline phosphatase obtained from rat bone marrow cells cultures, using a method that is simple, rapid and easy to reproduce. Its properties are compared with those of rat osseous plate enzyme and revealed that the alkaline phosphatase obtained has some kinetics and structural behaviors with higher levels of enzymatic activity, facilitating the comprehension of the mineralization process and its function.

  4. Intermediate range order in alkaline borate glasses

    NASA Astrophysics Data System (ADS)

    Crupi, C.; Carini, G.; Ruello, G.; D'Angelo, G.

    2016-03-01

    We describe the neutron diffraction patterns of a series of alkaline borate glasses at different metal oxide content. Strong differences are observed in the intermediate range order as a function of the specific alkaline ion and of its concentration. On these results, we propose that the first sharp diffraction peak arises from correlations of atoms of voids and show that the compositional variation of this peak intensity in alkaline borate glasses is due to changes in the distribution of void sizes within the three-dimensional network. We argue that our interpretation in terms of interstitial (empty and/or filled) voids, having different sizes, provides a general explanation for all anomalous behaviours revealed for the first sharp diffraction peak.

  5. Mobilization of Manufactured Gas Plant Tar with Alkaline Flushing Solutions

    PubMed Central

    Hauswirth, Scott C.; Birak, Pamela Schultz; Rylander, Seth C.; Miller, Cass T.

    2011-01-01

    This experimental study investigates the use of alkaline and alkaline-polymer solutions for the mobilization of former manufactured gas plant (FMGP) tars. Tar-aqueous interfacial tensions (IFTs) and contact angles were measured, and column flushing experiments were conducted. NaOH solutions (0.01–1 wt.%) were found to significantly reduce tar-aqueous IFT. Contact angles indicated a shift to strongly water-wet, then to tar-wet conditions as NaOH concentration increased. Column experiments were conducted with flushing solutions containing 0.2, 0.35, and 0.5% NaOH, both with and without xanthan gum (XG). Between 10 and 44% of the residual tar was removed by solutions containing only NaOH, while solutions containing both NaOH and XG removed 81–93% of the tar with final tar saturations as low as 0.018. The mechanism responsible for the tar removal is likely a combination of reduced IFT, a favorable viscosity ratio, and tar bank formation. Such an approach may have practical applications and would be significantly less expensive than surfactant-based methods. PMID:22091957

  6. Dual regulation of the native ClC-K2 chloride channel in the distal nephron by voltage and pH

    PubMed Central

    Pinelli, Laurent; Nissant, Antoine; Edwards, Aurélie; Paulais, Marc

    2016-01-01

    ClC-K2, a member of the ClC family of Cl− channels and transporters, forms the major basolateral Cl− conductance in distal nephron epithelial cells and therefore plays a central role in renal Cl− absorption. However, its regulation remains largely unknown because of the fact that recombinant ClC-K2 has not yet been studied at the single-channel level. In the present study, we investigate the effects of voltage, pH, Cl−, and Ca2+ on native ClC-K2 in the basolateral membrane of intercalated cells from the mouse connecting tubule. The ∼10-pS channel shows a steep voltage dependence such that channel activity increases with membrane depolarization. Intracellular pH (pHi) and extracellular pH (pHo) differentially modulate the voltage dependence curve: alkaline pHi flattens the curve by causing an increase in activity at negative voltages, whereas alkaline pHo shifts the curve toward negative voltages. In addition, pHi, pHo, and extracellular Ca2+ strongly increase activity, mainly because of an increase in the number of active channels with a comparatively minor effect on channel open probability. Furthermore, voltage alters both the number of active channels and their open probability, whereas intracellular Cl− has little influence. We propose that changes in the number of active channels correspond to them entering or leaving an inactivated state, whereas modulation of open probability corresponds to common gating by these channels. We suggest that pH, through the combined effects of pHi and pHo on ClC-K2, might be a key regulator of NaCl absorption and Cl−/HCO3− exchange in type B intercalated cells. PMID:27574292

  7. Dual regulation of the native ClC-K2 chloride channel in the distal nephron by voltage and pH.

    PubMed

    Pinelli, Laurent; Nissant, Antoine; Edwards, Aurélie; Lourdel, Stéphane; Teulon, Jacques; Paulais, Marc

    2016-09-01

    ClC-K2, a member of the ClC family of Cl(-) channels and transporters, forms the major basolateral Cl(-) conductance in distal nephron epithelial cells and therefore plays a central role in renal Cl(-) absorption. However, its regulation remains largely unknown because of the fact that recombinant ClC-K2 has not yet been studied at the single-channel level. In the present study, we investigate the effects of voltage, pH, Cl(-), and Ca(2+) on native ClC-K2 in the basolateral membrane of intercalated cells from the mouse connecting tubule. The ∼10-pS channel shows a steep voltage dependence such that channel activity increases with membrane depolarization. Intracellular pH (pHi) and extracellular pH (pHo) differentially modulate the voltage dependence curve: alkaline pHi flattens the curve by causing an increase in activity at negative voltages, whereas alkaline pHo shifts the curve toward negative voltages. In addition, pHi, pHo, and extracellular Ca(2+) strongly increase activity, mainly because of an increase in the number of active channels with a comparatively minor effect on channel open probability. Furthermore, voltage alters both the number of active channels and their open probability, whereas intracellular Cl(-) has little influence. We propose that changes in the number of active channels correspond to them entering or leaving an inactivated state, whereas modulation of open probability corresponds to common gating by these channels. We suggest that pH, through the combined effects of pHi and pHo on ClC-K2, might be a key regulator of NaCl absorption and Cl(-)/HCO3 (-) exchange in type B intercalated cells.

  8. 17-4 PH and 15-5 PH

    NASA Technical Reports Server (NTRS)

    Johnson, Howard T.

    1995-01-01

    17-4 PH and 15-5 PH are extremely useful and versatile precipitation-hardening stainless steels. Armco 17-4 PH is well suited for the magnetic particle inspection requirements of Aerospace Material Specification. Armco 15-5 PH and 17-4 PH are produced in billet, plate, bar, and wire. Also, 15-5 PH is able to meet the stringent mechanical properties required in the aerospace and nuclear industries. Both products are easy to heat treat and machine, making them very useful in many applications.

  9. Identification of differentially expressed genes potentially involved in the tolerance of Lotus tenuis to long-term alkaline stress.

    PubMed

    Paz, Rosalía Cristina; Rocco, Rubén Anibal; Jiménez-Bremont, Juan Francisco; Rodríguez-Kessler, Margarita; Becerra-Flora, Alicia; Menéndez, Ana Bernardina; Ruíz, Oscar Adolfo

    2014-09-01

    Soil alkalinity is one of the most serious agricultural problems limiting crop yields. The legume Lotus tenuis is an important forage acknowledged by its ability to naturally grow in alkaline soils. To gain insight into the molecular responses that are activated by alkalinity in L. tenuis plants, subtractive cDNA libraries were generated from leaves and roots of these plants. Total RNAs of non-stressed plants (pH 5.8; E.C. 1.2), and plants stressed by the addition of 10 mM of NaHCO3 (pH 9.0; E.C. 1.9), were used as source of the driver and the tester samples, respectively. RNA samples were collected after 14 and 28 days of treatment. A total of 158 unigenes from leaves and 92 unigenes from roots were obtained and classified into 11 functional categories. Unigenes from these categories (4 for leaves and 8 for roots), that were related with nutrient metabolism and oxidative stress relief were selected, and their differential expression analyzed by qRT-PCR. These genes were found to be differentially expressed in a time dependent manner in L. tenuis during the alkaline stress application. Data generated from this study will contribute to the understanding of the general molecular mechanisms associated to plant tolerance under long-term alkaline stress in plants.

  10. Laser direct write of planar alkaline microbatteries

    NASA Astrophysics Data System (ADS)

    Arnold, C. B.; Kim, H.; Piqué, A.

    We are developing a laser engineering approach to fabricate and optimize alkaline microbatteries in planar geometries. The laser direct-write technique enables multicapability for adding, removing and processing material and provides the ability to pattern complicated structures needed for fabricating complete microbattery assemblies. In this paper, we demonstrate the production of planar zinc-silver oxide alkaline cells under ambient conditions. The microbattery cells exhibit 1.55-V open-circuit potentials, as expected for the battery chemistry, and show a flat discharge behavior under constant-current loads. High capacities of over 450 μAhcm-2 are obtained for 5-mm2 microbatteries.

  11. Alkaline earth filled nickel skutterudite antimonide thermoelectrics

    DOEpatents

    Singh, David Joseph

    2013-07-16

    A thermoelectric material including a body centered cubic filled skutterudite having the formula A.sub.xFe.sub.yNi.sub.zSb.sub.12, where A is an alkaline earth element, x is no more than approximately 1.0, and the sum of y and z is approximately equal to 4.0. The alkaline earth element includes guest atoms selected from the group consisting of Be, Mb, Ca, Sr, Ba, Ra and combinations thereof. The filled skutterudite is shown to have properties suitable for a wide variety of thermoelectric applications.

  12. Extracellular pH modulates GABAergic neurotransmission in rat hypothalamus.

    PubMed

    Chen, Z L; Huang, R Q

    2014-06-20

    Changes in extracellular pH have a modulatory effect on GABAA receptor function. It has been reported that pH sensitivity of the GABA receptor is dependent on subunit composition and GABA concentration. Most of previous investigations focused on GABA-evoked currents, which only reflect the postsynaptic receptors. The physiological relevance of pH modulation of GABAergic neurotransmission is not fully elucidated. In the present studies, we examined the influence of extracellular pH on the GABAA receptor-mediated inhibitory neurotransmission in rat hypothalamic neurons. The inhibitory postsynaptic currents (IPSCs), tonic currents, and the GABA-evoked currents were recorded with whole-cell patch techniques on the hypothalamic slices from Sprague-Dawley rats at 15-26 postnatal days. The amplitude and frequency of spontaneous GABA IPSCs were significantly increased while the external pH was changed from 7.3 to 8.4. In the acidic pH (6.4), the spontaneous GABA IPSCs were reduced in amplitude and frequency. The pH induced changes in miniature GABA IPSCs (mIPSCs) similar to that in spontaneous IPSCs. The pH effect on the postsynaptic GABA receptors was assessed with exogenously applied varying concentrations of GABA. The tonic currents and the currents evoked by sub-saturating concentration of GABA ([GABA]) (10 μM) were inhibited by acidic pH and potentiated by alkaline pH. In contrast, the currents evoked by saturating [GABA] (1mM) were not affected by pH changes. We also investigated the influence of pH buffers and buffering capacity on pH sensitivity of GABAA receptors on human recombinant α1β2γ2 GABAA receptors stably expressed in HEK 293 cells. The pH influence on GABAA receptors was similar in HEPES- and MES-buffered media, and not dependent on protonated buffers, suggesting that the observed pH effect on GABA response is a specific consequence of changes in extracellular protons. Our data suggest that the hydrogen ions suppress the GABAergic neurotransmission

  13. TASK-2 Channels Contribute to pH Sensitivity of Retrotrapezoid Nucleus Chemoreceptor Neurons

    PubMed Central

    Wang, Sheng; Benamer, Najate; Zanella, Sébastien; Kumar, Natasha N.; Shi, Yingtang; Bévengut, Michelle; Penton, David; Guyenet, Patrice G.; Lesage, Florian

    2013-01-01

    Phox2b-expressing glutamatergic neurons of the retrotrapezoid nucleus (RTN) display properties expected of central respiratory chemoreceptors; they are directly activated by CO2/H+ via an unidentified pH-sensitive background K+ channel and, in turn, facilitate brainstem networks that control breathing. Here, we used a knock-out mouse model to examine whether TASK-2 (K2P5), an alkaline-activated background K+ channel, contributes to RTN neuronal pH sensitivity. We made patch-clamp recordings in brainstem slices from RTN neurons that were identified by expression of GFP (directed by the Phox2b promoter) or β-galactosidase (from the gene trap used for TASK-2 knock-out). Whereas nearly all RTN cells from control mice were pH sensitive (95%, n = 58 of 61), only 56% of GFP-expressing RTN neurons from TASK-2−/− mice (n = 49 of 88) could be classified as pH sensitive (>30% reduction in firing rate from pH 7.0 to pH 7.8); the remaining cells were pH insensitive (44%). Moreover, none of the recorded RTN neurons from TASK-2−/− mice selected based on β-galactosidase activity (a subpopulation of GFP-expressing neurons) were pH sensitive. The alkaline-activated background K+ currents were reduced in amplitude in RTN neurons from TASK-2−/− mice that retained some pH sensitivity but were absent from pH-insensitive cells. Finally, using a working heart–brainstem preparation, we found diminished inhibition of phrenic burst amplitude by alkalization in TASK-2−/− mice, with apneic threshold shifted to higher pH levels. In conclusion, alkaline-activated TASK-2 channels contribute to pH sensitivity in RTN neurons, with effects on respiration in situ that are particularly prominent near apneic threshold. PMID:24107938

  14. Acidic Food pH Increases Palatability and Consumption and Extends Drosophila Lifespan12

    PubMed Central

    Deshpande, Sonali A; Yamada, Ryuichi; Mak, Christine M; Hunter, Brooke; Obando, Alina Soto; Hoxha, Sany; Ja, William W

    2015-01-01

    Background: Despite the prevalent use of Drosophila as a model in studies of nutrition, the effects of fundamental food properties, such as pH, on animal health and behavior are not well known. Objectives: We examined the effect of food pH on adult Drosophila lifespan, feeding behavior, and microbiota composition and tested the hypothesis that pH-mediated changes in palatability and total consumption are required for modulating longevity. Methods: We measured the effect of buffered food (pH 5, 7, or 9) on male gustatory responses (proboscis extension), total food intake, and male and female lifespan. The effect of food pH on germfree male lifespan was also assessed. Changes in fly-associated microbial composition as a result of food pH were determined by 16S ribosomal RNA gene sequencing. Male gustatory responses, total consumption, and male and female longevity were additionally measured in the taste-defective Pox neuro (Poxn) mutant and its transgenic rescue control. Results: An acidic diet increased Drosophila gustatory responses (40–230%) and food intake (5–50%) and extended survival (10–160% longer median lifespan) compared with flies on either neutral or alkaline pH food. Alkaline food pH shifted the composition of fly-associated bacteria and resulted in greater lifespan extension (260% longer median survival) after microbes were eliminated compared with flies on an acidic (50%) or neutral (130%) diet. However, germfree flies lived longer on an acidic diet (5–20% longer median lifespan) compared with those on either neutral or alkaline pH food. Gustatory responses, total consumption, and longevity were unaffected by food pH in Poxn mutant flies. Conclusions: Food pH can directly influence palatability and feeding behavior and affect parameters such as microbial growth to ultimately affect Drosophila lifespan. Fundamental food properties altered by dietary or drug interventions may therefore contribute to changes in animal physiology, metabolism, and

  15. pH and monovalent cations regulate cytosolic free Ca(2+) in E. coli.

    PubMed

    Naseem, Riffat; Holland, I Barry; Jacq, Annick; Wann, Kenneth T; Campbell, Anthony K

    2008-06-01

    The results here show for the first time that pH and monovalent cations can regulate cytosolic free Ca(2+) in E. coli through Ca(2+) influx and efflux, monitored using aequorin. At pH 7.5 the resting cytosolic free Ca(2+) was 0.2-0.5 microM. In the presence of external Ca(2+) (1 mM) at alkaline pH this rose to 4 microM, being reduced to 0.9 microM at acid pH. Removal of external Ca(2+) caused an immediate decrease in cytosolic free Ca(2+) at 50-100 nM s(-1). Efflux rates were the same at pH 5.5, 7.5 and 9.5. Thus, ChaA, a putative Ca(2+)/H(+)exchanger, appeared not to be a major Ca(2+)-efflux pathway. In the absence of added Na(+), but with 1 mM external Ca(2+), cytosolic free Ca(2+) rose to approximately 10 microM. The addition of Na(+)(half maximum 60 mM) largely blocked this increase and immediately stimulated Ca(2+) efflux. However, this effect was not specific, since K(+) also stimulated efflux. In contrast, an increase in osmotic pressure by addition of sucrose did not significantly stimulate Ca(2+) efflux. The results were consistent with H(+) and monovalent cations competing with Ca(2+) for a non-selective ion influx channel. Ca(2+) entry and efflux in chaA and yrbG knockouts were not significantly different from wild type, confirming that neither ChaA nor YrbG appear to play a major role in regulating cytosolic Ca(2+) in Escherichia coli. The number of Ca(2+) ions calculated to move per cell per second ranged from <1 to 100, depending on conditions. Yet a single eukaryote Ca(2+) channel, conductance 100 pS, should conduct >6 million ions per second. This raises fundamental questions about the nature and regulation of Ca(2+) transport in bacteria, and other small living systems such as mitochondria, requiring a new mathematical approach to describe such ion movements. The results have important significance in the adaptation of E. coli to different ionic environments such as the gut, fresh water and in sea water near sewage effluents.

  16. Cu(II) complex formation with xylitol in alkaline solutions.

    PubMed

    Norkus, Eugenijus; Vaiciūniene, Jūrate; Vuorinen, Tapani; Gaidamauskas, Ernestas; Reklaitis, Jonas; Jääskeläinen, Anna-Stiina; Crans, Debbie C

    2004-02-25

    The formation of four Cu(II)-xylitol complexes was observed in aqueous alkaline solutions (11.0< or =pH< or =14.0, I=1.0, 20 degrees C) by means of direct current polarography and VIS spectrophotometry. Mononuclear hydroxy complexes, CuXyl(OH)- (log beta=17.7 +/- 0.5), CuXyl(OH)2(2-) (log beta=20.2 +/- 0.3) and CuXyl2(OH)2(4-) (log beta=22.4 +/- 0.3), are formed at high ligand-to-metal ratios (L:M> or =10), whereas dinuclear complex Cu2Xyl (log beta=29.2 +/- 0.3) is the predominant species at low ligand-to-metal ratio (L:M=0.5). Diffusion coefficients and molar absorptivities of the complex species were determined. pH variable 13C NMR suggested that pKa values of xylitol are rather similar and equal to 13.8 +/- 0.2, 13.9 +/- 0.1 and 13.9 +/- 0.2 for OH-groups adjacent to (C-1,C-5), (C-3) and (C-2,C-4) carbon atoms, respectively.

  17. Laundry detergent compatibility of the alkaline protease from Bacillus cereus.

    PubMed

    Banik, Rathindra Mohan; Prakash, Monika

    2004-01-01

    The endogenous protease activity in various commercially available laundry detergents of international companies was studied. The maximum protease activity was found at 50 degrees C in pH range 10.5-11.0 in all the tested laundry detergents. The endogenous protease activity in the tested detergents retained up to 70% on incubation at 40 degrees C for 1 h, whereas less than 30% activity was only found on incubation at 50 degrees C for 1 h. The alkaline protease from an alkalophilic strain of Bacillus cereus was studied for its compatibility in commercial detergents. The cell free fermented broth from shake flask culture of the organism showed maximum activity at pH 10.5 and 50 degrees C. The protease from B. cereus showed much higher residual activity (more than 80%) on incubation with laundry detergents at 50 degrees C for 1 h or longer. The protease enzyme from B. cereus was found to be superior over the endogenous proteases present in the tested commercial laundry detergents in comparison to the enzyme stability during the washing at higher temperature, e.g., 40-50 degrees C.

  18. l-Glutamate-Dependent Medium Alkalinization by Asparagus Mesophyll Cells 1

    PubMed Central

    McCutcheon, Steve L.; Ciccarelli, Bruce W.; Chung, Induk; Shelp, Barry; Bown, Alan W.

    1988-01-01

    Mechanically isolated Asparagus sprengeri Regel mesophyll cells cause alkalinization of the suspension medium on the addition of l-glutamate or its analog l-methionine-d,l-sulfoximine. Using a radiolabeled pH probe, it was found that both compounds caused internal acidification whereas l-aspartate did not. Fusicoccin stimulated H+ efflux from the cells by 111% and the uptake of l-[U-14C]glutamate by 55%. Manometric experiments demonstrated that, unlike l-methionine-d,l-sulfoximine, l-glutamate stimulated CO2 evolution from nonilluminated cells. Simultaneous measurements of medium alkalinization and 14CO2 evolution upon the addition of labeled l-glutamate showed that alkalinization was immediate and reached a maximum value after 45 minutes whereas 14CO2 evolution exhibited a lag before its appearance and continued in a linear manner for at least 100 minutes. Rates of alkalinization and uptake of l-[U-14C]glutamate were higher in the light while rates of 14CO2 evolution were higher in the dark. The major labeled product of glutamate decarboxylation, γ-aminobutyric acid, was found in the cells and the suspension medium. Its addition to the cell suspension did not result in medium alkalinization and evidence indicates that it is lost from the cell to the medium. The data suggest that the origin of medium alkalinization is co-transport not metabolism, and that the loss of labeled CO2 and γ-aminobutyric acid from the cell result in an overestimation of the stoichiometry of the H+/l-glutamate uptake process. Images Fig. 5 PMID:16666418

  19. Alkaline hydrothermal liquefaction of swine carcasses to bio-oil

    SciTech Connect

    Zheng, Ji-Lu Zhu, Ming-Qiang; Wu, Hai-tang

    2015-09-15

    Highlights: • Swine carcasses can be converted to bio-oil by alkaline hydrothermal liquefaction. • It seems that the use of the bio-oil for heat or CHP is technically suitable. • Some valuable chemicals were found in the bio-oils. • The bio-oil and the solid residue constituted an energy efficiency of 93.63% for the feedstock. • The solid residue can be used as a soil amendment, to sequester C and for preparing activated carbon. - Abstract: It is imperative that swine carcasses are disposed of safely, practically and economically. Alkaline hydrothermal liquefaction of swine carcasses to bio-oil was performed. Firstly, the effects of temperature, reaction time and pH value on the yield of each liquefaction product were determined. Secondly, liquefaction products, including bio-oil and solid residue, were characterized. Finally, the energy recovery ratio (ERR), which was defined as the energy of the resultant products compared to the energy input of the material, was investigated. Our experiment shows that reaction time had certain influence on the yield of liquefaction products, but temperature and pH value had bigger influence on the yield of liquefaction products. Yields of 62.2 wt% bio-oil, having a high heating value of 32.35 MJ/kg and a viscosity of 305cp, and 22 wt% solid residue were realized at a liquefaction temperature of 250 °C, a reaction time of 60 min and a pH value of 9.0. The bio-oil contained up to hundreds of different chemical components that may be classified according to functional groups. Typical compound classes in the bio-oil were hydrocarbons, organic acids, esters, ketones and heterocyclics. The energy recovery ratio (ERR) reached 93.63%. The bio-oil is expected to contribute to fossil fuel replacement in stationary applications, including boilers and furnaces, and upgrading processes for the bio-oil may be used to obtain liquid transport fuels.

  20. Effects of pH on aquatic biodegradation processes

    NASA Astrophysics Data System (ADS)

    Krachler, R. F.; Krachler, R.; Stojanovic, A.; Wielander, B.; Herzig, A.

    2009-01-01

    To date, little is known about the pH-stimulated mineralization of organic matter in aquatic environments. In this study, we investigated biodegradation processes in alkaline waters. Study site is a large shallow soda lake in Central Europe (Neusiedler See/Ferto). The decomposition rate of plant litter was measured as a function of pH by incubating air-saturated lake-water samples in contact with Phragmites litter (leaves) from the littoral vegetation. All samples showed high decomposition rates (up to 32% mass loss within 35 days) and a characteristic two-step degradation mechanism. During the degradation process, the solid plant litter was dissolved forming humic colloids. Subsequently, the humic colloids were mineralized to CO2 in the water column. The decomposition rate was linearly related to pH. Increasing pH values accelerated significantly the leaching of humic colloids as well as the final degradation process. The observed two-step mechanism controls the wetland/lake/air carbon fluxes, since large quantities of humic colloids are currently produced in the reed belt, exported through wind-driven circulations and incorporated into the open lake foodweb. At present, the lake is rapidly shrinking due to peat deposition in the littoral zone, whereas it has been resistant to silting-up processes for thousands of years. In order to investigate the cause of this abrupt change, the chemical composition of the lake-water was measured during 1995-2007. A thorough analysis of these data revealed that major lake-water discharges through the lake's artificial outlet channel led to a decline in salinity and alkalinity. According to our estimates, the lake's original salinity and alkalinity was 70-90% higher compared to the present conditions, with the consequence of substantially lower pH values in the present lake. The observed pH dependence of reed litter biodegradation rates points to a causal connection between low pH values and accumulation of peat in the lake basin

  1. Evaluation of alkaline phosphatase detection in dairy products using a modified rapid chemiluminescent method and official methods.

    PubMed

    Albillos, S M; Reddy, R; Salter, R

    2011-07-01

    Alkaline phosphatase is a ubiquitous milk enzyme that historically has been used to verify adequate pasteurization of milk for public health purposes. Current approved methods for detection of alkaline phosphatase in milk include the use of enzyme photoactivated substrates to give readings in milliunits per liter. The U.S. and European public health limit for alkaline phosphatase in pasteurized drinks is 350 mU/liter. A modified chemiluminescent method, fast alkaline phosphatase, was compared with the approved fluorometric and chemiluminescent alkaline phosphatase methods to determine whether the modified method was equivalent to the approved methods and suitable for detecting alkaline phosphatase in milk. Alkaline phosphatase concentrations in cow's, goat's, and sheep's milk and in flavored drinks and cream were determined by three methods. Evaluations in each matrix were conducted with pasteurized samples spiked with raw milk to produce alkaline phosphatase concentrations of 2 to 5,000 mU/liter. The tests were performed by the method developer and then reproduced at a laboratory at the National Center for Food Safety and Technology following the criteria for a single laboratory validation. The results indicated that the fast alkaline phosphatase method was not significantly different from the approved chemiluminescent method, with a limit of detection of 20 to 50 mU/liter in all the studied matrices. This modified chemiluminescent method detects alkaline phosphatase in the 350 mU/liter range with absolute differences from triplicate data that are lower and within the range of the allowed intralaboratory repeatability values published for the approved chemiluminescent method.

  2. Identification of a New Marine Bacterial Strain SD8 and Optimization of Its Culture Conditions for Producing Alkaline Protease.

    PubMed

    Cui, Hongxia; Yang, Muyang; Wang, Liping; Xian, Cory J

    2015-01-01

    While much attention has been given to marine microorganisms for production of enzymes, which in general are relatively more stable and active compared to those from plants and animals, studies on alkaline protease production from marine microorganisms have been very limited. In the present study, the alkaline protease producing marine bacterial strain SD8 isolated from sea muds in the Geziwo Qinhuangdao sea area of China was characterized and its optimal culture conditions were investigated. Strain SD8 was initially classified to belong to genus Pseudomonas by morphological, physiological and biochemical characterizations, and then through 16S rDNA sequence it was identified to be likely Pseudomonas hibiscicola. In addition, the culture mediums, carbon sources and culture conditions of strain SD8 were optimized for maximum production of alkaline protease. Optimum enzyme production (236U/mL when cultured bacteria being at 0.75 mg dry weight/mL fermentation broth) was obtained when the isolate at a 3% inoculum size was grown in LB medium at 20 mL medium/100mL Erlenmeyer flask for 48h culture at 30°C with an initial of pH 7.5. This was the first report of strain Pseudomonas hibiscicola secreting alkaline protease, and the data for its optimal cultural conditions for alkaline protease production has laid a foundation for future exploration for the potential use of SD8 strain for alkaline protease production.

  3. Identification of a New Marine Bacterial Strain SD8 and Optimization of Its Culture Conditions for Producing Alkaline Protease

    PubMed Central

    Cui, Hongxia; Yang, Muyang; Wang, Liping; Xian, Cory J.

    2015-01-01

    While much attention has been given to marine microorganisms for production of enzymes, which in general are relatively more stable and active compared to those from plants and animals, studies on alkaline protease production from marine microorganisms have been very limited. In the present study, the alkaline protease producing marine bacterial strain SD8 isolated from sea muds in the Geziwo Qinhuangdao sea area of China was characterized and its optimal culture conditions were investigated. Strain SD8 was initially classified to belong to genus Pseudomonas by morphological, physiological and biochemical characterizations, and then through 16S rDNA sequence it was identified to be likely Pseudomonas hibiscicola. In addition, the culture mediums, carbon sources and culture conditions of strain SD8 were optimized for maximum production of alkaline protease. Optimum enzyme production (236U/mL when cultured bacteria being at 0.75 mg dry weight/mL fermentation broth) was obtained when the isolate at a 3% inoculum size was grown in LB medium at 20 mL medium/100mL Erlenmeyer flask for 48h culture at 30°C with an initial of pH 7.5. This was the first report of strain Pseudomonas hibiscicola secreting alkaline protease, and the data for its optimal cultural conditions for alkaline protease production has laid a foundation for future exploration for the potential use of SD8 strain for alkaline protease production. PMID:26716833

  4. Improvement of thermoelectric properties of alkaline-earth hexaborides

    SciTech Connect

    Takeda, Masatoshi . E-mail: takeda@mech.nagaokaut.ac.jp; Terui, Manabu; Takahashi, Norihito; Ueda, Noriyoshi

    2006-09-15

    Thermoelectric (TE) and transport properties of alkaline-earth hexaborides were examined to investigate the possibility of improvement in their TE performance. As carrier concentration increased, electrical conductivity increased and the absolute value of the Seebeck coefficient decreased monotonically, while carrier mobility was almost unchanged. These results suggest that the electrical properties of the hexaboride depend largely on carrier concentration. Thermal conductivity of the hexaboride was higher than 10 W/m K even at 1073 K, which is relatively high among TE materials. Alloys of CaB{sub 6} and SrB{sub 6} were prepared in order to reduce lattice thermal conductivity. Whereas the Seebeck coefficient and electrical conductivity of the alloys were intermediate between those of CaB{sub 6} and SrB{sub 6} single phases, the thermal conductivities of the alloys were lower than those of both single phases. The highest TE performance was obtained in the vicinity of Ca{sub 0.5}Sr{sub 0.5}B{sub 6}, indicating that alloying is effective in improving the performance. - Graphical abstract: Thermoelectric figure-of-merit, ZT, for (Ca,Sr)B{sub 6} alloys. The highest ZT value of 0.35 at 1073 K was obtained due to effective reduction of thermal conductivity by alloying.

  5. [Impacts of alkaline thermal treatment on characteristics of sludge from sewage treatment plant].

    PubMed

    Yang, Shi-Dong; Chen, Xia; Liu, Cao; Xiao, Ben-Yi

    2015-02-01

    Alkaline thermal treatment is an important pretreatment method for sewage sludge. In this paper, in order to optimize the alkaline thermal treatment conditions for sludge pretreatment, four pretreatment parameters ( sludge concentration, pH, temperature and treatment time) were investigated through orthogonal experiments to determine their effects on the sludge disintegration, sludge concentration and sludge morphology of sewage sludge. The experimental results showed that the significance of the four factors on sludge characteristics was in the order of pH > temperature > treatment time > sludge concentration. Additionally, the optimal conditions of the four factors for the release of soluble chemical oxygen demand (SCOD) of unit sludge and decrease of sludge concentration were as follows: 36.55 g x L(-1), pH 12.45, 175 degrees C and 60 min. While the optimal conditions for the decrease of particle size and fractal dimension were 36.55 g x L(-1), pH 12.5, 175 degrees C and 45 min.

  6. Differences in the chemical composition of Enterococcus faecalis biofilm under conditions of starvation and alkalinity.

    PubMed

    Chen, Weixu; Liang, Jingping; He, Zhiyan; Jiang, Wei

    2017-01-02

    ABSTACT This study aimed to investigate the dynamic changes that occur in the chemical composition of an Enterococcus faecalis (E. faecalis) biofilm under conditions of starvation and in an alkaline environment and to explore the function of chemical composition changes in the resistance of the E. faecalis biofilm to an extreme environment. This study established an in vitro E. faecalis biofilm model under starvation and in an alkaline environment. During the formation of the biofilm, the pH value and nutritional condition of the culture medium were changed, and the changes in chemical composition were observed using biochemical measures. The results showed that, when the