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Sample records for acetate-acetic acid buffer

  1. Use of pooled sodium acetate acetic acid formalin-preserved fecal specimens for the detection of intestinal parasites.

    PubMed

    Gaafar, Maha R

    2011-01-01

    This study aimed at comparing detection of intestinal parasites from single unpreserved stool sample vs. sodium acetate acetic acid formalin (SAF)-preserved pooled samples, and stained with chlorazol black dye in routine practice. Unpreserved samples were collected from 120 patients and represented as Group I. Other three SAF-preserved samples were collected from the same patients over a 6-day period and represented as Groups IIa, IIb, and IIc. The latter groups were equally subdivided into two subgroups. The first subgroup of each of the three samples was examined individually, whereas the second subgroup of each were pooled and examined as a single specimen. All groups were examined by the routine diagnostic techniques; however, in group II when the diagnosis was uncertain, the chlorazol black dye staining procedure was carried out. Results demonstrated that out of 74 patients who continued the study, 12 cases (16%) were positive in group I, compared with 29 (39%) in the subgroups examined individually, and 27 (36%) in the pooled subgroups. Therefore, pooling of preserved fecal samples is an efficient and economical procedure for the detection of parasites. Furthermore, the chlorazol black dye was simple and effective in detecting the nuclear details of different parasites. PMID:21567472

  2. Comparison of Buffer Effect of Different Acids During Sandstone Acidizing

    NASA Astrophysics Data System (ADS)

    Umer Shafiq, Mian; Khaled Ben Mahmud, Hisham; Hamid, Mohamed Ali

    2015-04-01

    The most important concern of sandstone matrix acidizing is to increase the formation permeability by removing the silica particles. To accomplish this, the mud acid (HF: HCl) has been utilized successfully for many years to stimulate the sandstone formations, but still it has many complexities. This paper presents the results of laboratory investigations of different acid combinations (HF: HCl, HF: H3PO4 and HF: HCOOH). Hydrofluoric acid and fluoboric acid are used to dissolve clays and feldspar. Phosphoric and formic acids are added as a buffer to maintain the pH of the solution; also it allows the maximum penetration of acid into the core sample. Different tests have been performed on the core samples before and after the acidizing to do the comparative study on the buffer effect of these acids. The analysis consists of permeability, porosity, color change and pH value tests. There is more increase in permeability and porosity while less change in pH when phosphoric and formic acids were used compared to mud acid. From these results it has been found that the buffer effect of phosphoric acid and formic acid is better than hydrochloric acid.

  3. Reductive dechlorination of carbon tetrachloride using buffered alkaline ascorbic acid.

    PubMed

    Lin, Ya-Ting; Liang, Chenju

    2015-10-01

    Alkaline ascorbic acid (AA) was recently discovered as a novel in-situ chemical reduction (ISCR) reagent for remediating chlorinated solvents in the subsurface. For this ISCR process, the maintenance of an alkaline pH is essential. This study investigated the possibility of the reduction of carbon tetrachloride (CT) using alkaline AA solution buffered by phosphate and by NaOH. The results indicated that CT was reduced by AA, and chloroform (CF) was a major byproduct at a phosphate buffered pH of 12. However, CT was completely reduced by AA in 2M NaOH without CF formation. In the presence of iron/soil minerals, iron could be reduced by AA and Fe(2+) tends to precipitate on the mineral surface to accelerate CT degradation. A simultaneous transfer of hydrogenolysis and dichloroelimination would occur under phosphate buffered pH 12. This implies that a high alkaline environment is a crucial factor for maintaining the dominant pathway of two electron transfer from dianionic AA to dehydroascorbic acid, and to undergo dichloroelimination of CT. Moreover, threonic acid and oxalic acid were identified to be the major AA decomposition products in alkaline solutions. PMID:25912910

  4. Selective formation of organo, organo-aqueous, and hydro gel-like materials from partially hydrolysed poly(vinyl acetate)s based on different boron-containing crosslinkers.

    PubMed

    Angelova, L V; Leskes, M; Berrie, B H; Weiss, R G

    2015-07-01

    Viscoelastic, gel-like, polymeric dispersions (HVPDs) can be prepared by crosslinking polyols with borax or boric acid in water under alkaline conditions. Rheologically similar HVPDs have been prepared in organic liquids containing no water or hydroxylic groups through crosslinking partially or fully hydrolysed poly(vinyl acetate)s with trimethyl borate, boric acid, or borax. The organo-HVPDs are water-sensitive and rheoreversible on exposure to water. They were characterised rheologically and by solution and solid-state (11)B NMR spectroscopy. Spectroscopic analyses show the presence of mono- and di-diol crosslinks, as well as non-crosslinked boron species in HVPDs prepared with trimethyl borate or boric acid. The number of crosslinks in organo-HVPDs prepared with borax increased over the course of several days. Results from solution and solid-state (11)B NMR spectroscopy are comparable; no solid-like component was detectable. We demonstrate that hydro, organo, or organo-aqueous HVPDs can be obtained from partially hydrolysed poly(vinyl acetate)s by 'tuning' the structure of the boron-based crosslinker. PMID:26027551

  5. Analysis of Natural Buffer Systems and the Impact of Acid Rain

    ERIC Educational Resources Information Center

    Powers, David C.; Yoder, Claude H.; Higgs, Andrew T.; Obley, Matt L.; Hess, Kenneth R.; Leber, Phyllis A.

    2005-01-01

    The environmental significance of acid rain on water systems of different buffer capacities is discussed. The most prevalent natural buffer system is created by the equilibrium between carbonate ions and carbon dioxide.

  6. Tested Demonstrations: Buffer Capacity of Various Acetic Acid-Sodium Acetate Systems: A Lecture Experiment.

    ERIC Educational Resources Information Center

    Donahue, Craig J.; Panek, Mary G.

    1985-01-01

    Background information and procedures are provided for a lecture experiment which uses indicators to illustrate the concept of differing buffer capacities by titrating acetic acid/sodium acetate buffers with 1.0 molar hydrochloric acid and 1.0 molar sodium hydroxide. A table with data used to plot the titration curve is included. (JN)

  7. Influence of phosphate ions on buffer capacity of soil humic acids

    NASA Astrophysics Data System (ADS)

    Boguta, P.; Sokołowska, Z.

    2012-02-01

    The object of this study was to determine change of natural buffer capacity of humic acids by strong buffering agents, which were phosphate ions. Studies were carried out on the humic acids extracted from peat soils. Additional information was obtained by determination of water holding capacity, density, ash and pH for peats and optical parameter Q4/6 for humic acids. Humic acid suspensions exhibited the highest buffer properties at low pH and reached maximum at pH ~ 4. Phosphates possessed buffer properties in the pH range from 4.5 to 8.0. The maximum of buffering was at pH~6.8 and increased proportionally with an increase in the concentration of phosphate ions. The study indicated that the presence of phosphate ions may strongly change natural buffer capacity of humic acids by shifting buffering maximum toward higher pH values. Significant correlations were found for the degree of the secondary transformation with both the buffer capacity and the titrant volume used during titration.

  8. Improving impurities clearance by amino acids addition to buffer solutions for chromatographic purifications of monoclonal antibodies.

    PubMed

    Ishihara, Takashi; Hosono, Mareto

    2015-07-15

    The performance of amino acids in Protein A affinity chromatography, anion exchange chromatography and cation exchange chromatography for monoclonal antibody purification was investigated. Glycine, threonine, arginine, glutamate, and histidine were used as buffer components in the equilibration, washing, and elution steps of these chromatographies. Improved clearance of impurity, high molecular weight species (HMW) and host cell proteins (HCP) was observed in the purification processes when using the amino acids as base-buffer constituents, additives or eluents compared with that of buffers without these amino acids. In addition, we designed a buffer system in which the mobile phases were composed of only a single amino acid, histidine, and applied it to the above three chromatographies. Effective HMW and HCP clearance was also obtained in this manner. These results suggest that amino acids may enhance impurity clearance during the purification of monoclonal antibodies. PMID:26057847

  9. Buffer capacities of podzolic and peat gleyic podzolic soils to sulfuric and nitric acids

    NASA Astrophysics Data System (ADS)

    Kuznetsov, N. B.; Alekseeva, S. A.; Shashkova, G. V.; Dronova, T. Ya.; Sokolova, T. A.

    2007-04-01

    Soil samples from the main genetic horizons of pale podzolic and peat gleyic podzolic soils from the Central Forest Reserve were subjected to a continuous potentiometric titration by sulfuric and nitric acids. The sulfate sorption capacity was determined in soil mineral horizons. The buffer capacity of mineral horizons of both soils to sulfuric acid was found to be higher than that to the nitric acid. This is explained by the sorption of sulfates via the mechanism of ligand exchange with the release of hydroxyl groups from the surfaces of Fe and Al hydroxide particles and edge faces of clay crystallites. The buffer capacity of organic horizons of the pale podzolic soil to sulfuric acid proved to be higher than that to nitric acid; in organic horizons of the peat gleyic podzolic soil, the buffer capacity to sulfuric acid was lower than that to nitric acid. The reasons for this phenomenon have yet to be investigated.

  10. Development and evaluation of acid-buffering bioadhesive vaginal tablet for mixed vaginal infections.

    PubMed

    Alam, Mohd Aftab; Ahmad, Farhan Jalees; Khan, Zeenat Iqbal; Khar, Roop Krishen; Ali, Mushir

    2007-01-01

    An acid-buffering bioadhesive vaginal tablet was developed for the treatment of genitourinary tract infections. From the bioadhesion experiment and release studies it was found that polycarbophil and sodium carboxymethylcellulose is a good combination for an acid-buffering bioadhesive vaginal tablet. Sodium monocitrate was used as a buffering agent to provide acidic pH (4.4), which is an attribute of a healthy vagina. The effervescent mixture (citric acid and sodium bicarbonate) along with a superdisintegrant (Ac-Di-sol) was used to enhance the swellability of the bioadhesive tablet. The drugs clotrimazole (antifungal) and metronidazole (antiprotozoal as well as an antibacterial) were used in the formulation along with Lactobacillus acidophilus spores to treat mixed vaginal infections. From the ex vivo retention study it was found that the bioadhesive polymers hold the tablet for more than 24 hours inside the vaginal tube. The hardness of the acid-buffering bioadhesive vaginal tablet was optimized, at 4 to 5 kg hardness the swelling was found to be good and the cumulative release profile of the developed tablet was matched with a marketed conventional tablet (Infa-V). The in vitro spreadability of the swelled tablet was comparable to the marketed gel. In the in vitro antimicrobial study it was found that the acid-buffering bioadhesive tablet produces better antimicrobial action than marketed intravaginal drug delivery systems (Infa-V, Candid-V and Canesten 1). PMID:18181530

  11. Exciton-blocking phosphonic acid-treated anode buffer layers for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Zimmerman, Jeramy D.; Song, Byeongseop; Griffith, Olga; Forrest, Stephen R.

    2013-12-01

    We demonstrate significant improvements in power conversion efficiency of bilayer organic photovoltaics by replacing the exciton-quenching MoO3 anode buffer layer with an exciton-blocking benzylphosphonic acid (BPA)-treated MoO3 or NiO layer. We show that the phosphonic acid treatment creates buffers that block up to 70% of excitons without sacrificing the hole extraction efficiency. Compared to untreated MoO3 anode buffers, BPA-treated NiO buffers exhibit a ˜ 25% increase in the near-infrared spectral response in diphenylanilo functionalized squaraine (DPSQ)/C60-based bilayer devices, increasing the power conversion efficiency under 1 sun AM1.5G simulated solar illumination from 4.8 ± 0.2% to 5.4 ± 0.3%. The efficiency can be further increased to 5.9 ± 0.3% by incorporating a highly conductive exciton blocking bathophenanthroline (BPhen):C60 cathode buffer. We find similar increases in efficiency in two other small-molecule photovoltaic systems, indicating the generality of the phosphonic acid-treated buffer approach to enhance exciton blocking.

  12. Buffer interference with protein dynamics: a case study on human liver fatty acid binding protein.

    PubMed

    Long, Dong; Yang, Daiwen

    2009-02-18

    Selection of suitable buffer types is often a crucial step for generating appropriate protein samples for NMR and x-ray crystallographic studies. Although the possible interaction between MES buffer (2-(N-morpholino)ethanesulfonic acid) and proteins has been discussed previously, the interaction is usually thought to have no significant effects on the structures of proteins. In this study, we demonstrate the direct, albeit weak, interaction between MES and human liver fatty acid binding protein (hLFABP). Rather than affecting the structure of hLFABP, we found that the dynamics of hLFABP, which were previously proposed to be relevant to its functions, were significantly affected by the binding of hLFABP with MES. Buffer interference with protein dynamics was also demonstrated with Bis-Tris buffer, which is quite different from MES and fatty acids in terms of their molecular structures and properties. This result, to our knowledge, is the first published report on buffer interference with protein dynamics on a microsecond to millisecond timescale and could represent a generic problem in the studies of functionally relevant protein dynamics. Although being a fortuity, our finding of buffer-induced changes in protein dynamics offers a clue to how hLFABP accommodates its ligands. PMID:19217864

  13. Leaching with Penicillium simplicissimum: Influence of Metals and Buffers on Proton Extrusion and Citric Acid Production

    PubMed Central

    Franz, Andreas; Burgstaller, Wolfgang; Schinner, Franz

    1991-01-01

    In the presence of insoluble metal oxides (industrial filter dust, zinc oxide, synthetic mixture of metal oxides), Penicillium simplicissimum developed the ability to excrete considerable amounts of citric acid (>100 mM). Parallel with the increase of citric acid concentration in the culture broth, zinc was solubilized from zinc oxide. The adsorption of filter dust onto the mycelium (the pellets formed were less than 1 mm in diameter) was required for not only the citric acid excretion but also the leaching of zinc. When the filter dust was replaced with a synthetic mixture of metal oxides or with zinc oxide in combination with trace elements, levels of adsorption and citric acid production were observed to be similar to those in experiments where industrial filter dust was used. The two most important properties of the filter dust were its heavy-metal content and its buffering capacity. These properties were simulated by adding heavy metals in soluble form (as chlorides, sulfates, or nitrates) or soluble buffers to the medium. Both heavy metals and buffers were not able to induce a citric acid efflux. As with citric acid production by Aspergillus niger, the addition of manganese lowered citric acid excretion (by 40% with metal oxide-induced citric acid efflux and by 100% with urea-induced citric acid efflux). Copper antagonized the effect of manganese. The mechanism for the bulk of citric acid excretion by P. simplicissimum, however, seemed to be different from that described for citric acid accumulation by A. niger. Because of the inefficiency of metals in solubilized form and of soluble buffers to induce a strong citric acid efflux, adsorption of an insoluble metal compound (zinc oxide) turned out to be essential. Surface phenomena possibly involving the plasma membrane H+-ATPase are thought to participate in the induction of citric acid excretion by P. simplicissimum in the presence of industrial filter dust. PMID:16348442

  14. Leaching with Penicillium simplicissimum: Influence of metals and buffers on proton extrusion and citric acid production

    SciTech Connect

    Franz, A.; Burgstaller, W.; Schinner, F. )

    1991-03-01

    In the presence of insoluble metal oxides (industrial filter dust, zinc oxide, synthetic mixture of metal oxides), Penicillium simplicissimum developed the ability to excrete considerable amounts of citric acid (>100 mM). Parallel with the increase of citric acid concentration in the culture broth, zinc was solubilized from zinc oxide. The adsorption of filter dust onto the mycelium (the pellets formed were less than 1 mm in diameter) was required for not only the citric acid excretion but also the leaching of zinc. When the filter dust was replaced with a synthetic mixture of metal oxides or with zinc oxide in combination with trace elements, levels of adsorption and citric acid production were observed to be similar to those in experiments where industrial filter dust was used. The two most important properties of the filter dust were its heavy-metal content and its buffering capacity. These properties were simulated by adding heavy metals in soluble form (as chlorides, sulfates, or nitrates) or soluble buffers to the medium. Both heavy metals and buffers were not able to induce a citric acid efflux. As with citric acid production by Aspergillus niger, the addition of manganese lowered citric acid excretion (by 40% with metal oxide-induced citric acid efflux and by 100% with urea-induced citric acid efflux). Copper antagonized the effect of manganese. The mechanism for the bulk of citric acid excretion by P. simplicissimum, however, seemed to be different from that described for citric acid accumulation by A. niger. Because of the inefficiency of metals in solubilized form and of soluble buffers to induce a strong citric acid efflux, adsorption of an insoluble metal compound (zinc oxide) turned out to be essential.

  15. Comparison of peak shape in hydrophilic interaction chromatography using acidic salt buffers and simple acid solutions.

    PubMed

    Heaton, James C; Russell, Joseph J; Underwood, Tim; Boughtflower, Robert; McCalley, David V

    2014-06-20

    The retention and peak shape of neutral, basic and acidic solutes was studied on hydrophilic interaction chromatography (HILIC) stationary phases that showed both strong and weak ionic retention characteristics, using aqueous-acetonitrile mobile phases containing either formic acid (FA), ammonium formate (AF) or phosphoric acid (PA). The effect of organic solvent concentration on the results was also studied. Peak shape was good for neutrals under most mobile phase conditions. However, peak shapes for ionised solutes, particularly for basic compounds, were considerably worse in FA than AF. Even neutral compounds showed deterioration in performance with FA when the mobile phase water concentration was reduced. The poor performance in FA cannot be entirely attributed to the negative impact of ionic retention on ionised silanols on the underlying silica base materials, as results using PA at lower pH (where their ionisation is suppressed) were inferior to those in AF. Besides the moderating influence of the salt cation on ionic retention, it is likely that salt buffers improve peak shape due to the increased ionic strength of the mobile phase and its impact on the formation of the water layer on the column surface. PMID:24813934

  16. Matching phosphate and maleate buffer systems for dissolution of weak acids: Equivalence in terms of buffer capacity of bulk solution or surface pH?

    PubMed

    Cristofoletti, Rodrigo; Dressman, Jennifer B

    2016-06-01

    The development of in vitro dissolution tests able to anticipate the in vivo fate of drug products has challenged pharmaceutical scientists over time, especially in the case of ionizable compounds. In the seminal model proposed by Mooney et al. thirty-five years ago, the pH at the solid-liquid interface (pH0) was identified as a key parameter in predicting dissolution rate. In the current work it is demonstrated that the in vitro dissolution of the weak acid ibuprofen in maleate and phosphate buffer systems is a function of the pH0, which in turn is affected by properties of the drug and the medium. The reported pH0 for ibuprofen dissolution in bicarbonate buffer, the predominant buffer species in the human small intestine under fasting conditions, can be achieved by reducing the phosphate buffer concentration to 5.0mM or the maleate buffer concentration to 2.2mM. Using this approach to identify the appropriate buffer/buffer capacity combination for in vitro experiments in FaSSIF-type media, it would be possible to increase the physiological relevance of this important biopharmaceutics tool. However, the necessity of monitoring and adjusting the bulk pH during the experiments carried out in 5.0mM phosphate or 2.2mM maleate buffers must also be taken into consideration. PMID:27032508

  17. Ligand-enhanced electrokinetic remediation of metal-contaminated marine sediments with high acid buffering capacity.

    PubMed

    Masi, Matteo; Iannelli, Renato; Losito, Gabriella

    2016-06-01

    The suitability of electrokinetic remediation for removing heavy metals from dredged marine sediments with high acid buffering capacity was investigated. Laboratory-scale electrokinetic remediation experiments were carried out by applying two different voltage gradients to the sediment (0.5 and 0.8 V/cm) while circulating water or two different chelating agents at the electrode compartments. Tap water, 0.1 M citric acid and 0.1 M ethylenediaminetetraacetic acid (EDTA) solutions were used respectively. The investigated metals were Zn, Pb, V, Ni and Cu. In the unenhanced experiment, the acid front could not propagate due to the high acid buffering capacity of the sediments; the production of OH(-) ions at the cathode resulted in a high-pH environment causing the precipitation of CaCO3 and metal hydroxides. The use of citric acid prevented the formation of precipitates, but solubilisation and mobilisation of metal species were not sufficiently achieved. Metal removal was relevant when EDTA was used as the conditioning agent, and the electric potential was raised up to 0.8 V/cm. EDTA led to the formation of negatively charged complexes with metals which migrated towards the anode compartment by electromigration. This result shows that metal removal from sediments with high acid buffering capacity may be achieved by enhancing the electrokinetic process by EDTA addition when the acidification of the medium is not economically and/or environmentally sustainable. PMID:26490900

  18. Interference by morpholine ethanesulfonic acid (MES) and related buffers in phenolic oxidation by peroxidase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While characterizing the kinetic parameters of apoplastic phenolic oxidation by peroxidase, we found anomalies caused by the 4-morpholine ethanesulfonic acid (MES) buffer being used. In the presence of MES, certain phenolics appeared not to be oxidized by peroxidase, yet the oxidant, H2O2, was uti...

  19. Defining the buffering process by a triprotic acid without relying on Stewart-electroneutrality considerations.

    PubMed

    Nguyen, Minhtri K; Kao, Liyo; Kurtz, Ira

    2011-01-01

    Upon the addition of protons to an aqueous solution, a component of the H+ load will be bound i.e. buffered. In an aqueous solution containing a triprotic acid, H+ can be bound to three different states of the acid as well as to OH- ions that are derived from the auto-ionization of H2O. In quantifying the buffering process of a triprotic acid, one must define the partitioning of H+ among the three states of the acid and also the OH- ions in solution in order to predict the equilibrium pH value. However, previous quantitative approaches that model triprotic acid titration behaviour and used to predict the equilibrium pH rely on the mathematical convenience of electroneutrality/charge balance considerations. This fact has caused confusion in the literature, and has led to the assumption that charge balance/electroneutrality is a causal factor in modulating proton buffering (Stewart formulation). However, as we have previously shown, although charge balance can be used mathematically as a convenient tool in deriving various formulae, electroneutrality per se is not a fundamental physicochemical parameter that is mechanistically involved in the underlying buffering and proton transfer reactions. The lack of distinction between a mathematical tool, and a fundamental physicochemical parameter is in part a reason for the current debate regarding the Stewart formulation of acid-base analysis. We therefore posed the following question: Is it possible to generate an equation that defines and predicts the buffering of a triprotic acid that is based only on H+ partitioning without incorporating electroneutrality in the derivation? Towards this goal, we derived our new equation utilizing: 1) partitioning of H+ buffering; 2) conservation of mass; and 3) acid-base equilibria. In validating this model, we compared the predicted equilibrium pH with the measured pH of an aqueous solution consisting of Na2HPO4 to which HCl was added. The measured pH values were in excellent agreement

  20. Alteration of the surface charge of aluminum goethites by a sulfonic acid buffer.

    PubMed

    Cervini-Silva, Javiera

    2004-07-01

    Four samples of synthetic low-substitution Al-goethites (mol% Al<10) were incubated with 10 mM NaClO4 and 5 mM MES buffer (MES buffer (2-[N-morpholino]ethanesulfonic acid) at pH 5. It was found that MES buffer, although commonly used to control pH, profoundly affected the results of our electrophoretic mobility measurements. The presence of MES buffer caused a large decrease in EM values for unsubstituted goethite, from 5.7 +/- 0.7 to 1.8 +/- 0.4 m2 v(-1) s(-1), while increases in Al substitution in goethite led to a progressive increase in EM values. The charge reversal following addition of MES buffer to suspension containing Al-goethites was explained by specific sorption that, at pH 5, is thought to occur via cation surface complexation because of (i) sulfonate induced-dipole or (ii) N and O lone-pair dipole-dipole interactions with structural Fe. PMID:15158383

  1. Analysis of the amino acids of soy globulins by AOT reverse micelles and aqueous buffer.

    PubMed

    Zhao, Xiaoyan; Chen, Jun; Lu, Zhifang; Ling, Xiangqing; Deng, Peng; Zhu, Qingjun; Du, Fangling

    2011-10-01

    The 7S and 11S globulins from soybean proteins using reverse micelle and aqueous buffer extraction methods were characterized by using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscope (SEM), and their amino acid compositions were also evaluated. SDS-PAGE did not show electrophoretic differences between 7S and 11S globulin subunits with two extraction methods. SEM analysis showed that the AOT reverse micelle processing of 7S and 11S globulins induced a reduction of droplet size. Some individual amino acid contents of 7S and 11S globulins using two extraction methods were different, some were similar. In all the samples, the glutamic acid, aspartic acid, and leucine were the dominant amino acids while the cystine and methionine were the first-limiting amino acids. The proportion of essential amino acids to the total amino acids (E/T) of the 7S globulin from aqueous buffer and reverse micelles was similar. While significant differences were obtained in the proportion of E/T of the 11S globulin. PMID:21647686

  2. Dissolution properties of co-amorphous drug-amino acid formulations in buffer and biorelevant media.

    PubMed

    Heikkinen, A T; DeClerck, L; Löbmann, K; Grohganz, H; Rades, T; Laitinen, R

    2015-07-01

    Co-amorphous formulations, particularly binary drug-amino acid mixtures, have been shown to provide enhanced dissolution for poorly-soluble drugs and improved physical stability of the amorphous state. However, to date the dissolution properties (mainly intrinsic dissolution rate) of the co-amorphous formulations have been tested only in buffers and their supersaturation ability remain unexplored. Consequently, dissolution studies in simulated intestinal fluids need to be conducted in order to better evaluate the potential of these systems in increasing the oral bioavailability of biopharmaceutics classification system class II drugs. In this study, solubility and dissolution properties of the co-amorphous simvastatin-lysine, gibenclamide-serine, glibenclamide-threonine and glibenclamide-serine-threonine were studied in phosphate buffer pH 7.2 and biorelevant media (fasted and fed state simulated intestinal fluids (FaSSIF and FeSSIF, respectively)). The co-amorphous formulations were found to provide a long-lasting supersaturation and improve the dissolution of the drugs compared to the crystalline and amorphous drugs alone in buffer. Similar improvement, but in lesser extent, was observed in biorelevant media suggesting that a dissolution advantage observed in aqueous buffers may overestimate the advantage in vivo. However, the results show that, in addition to stability advantage shown earlier, co-amorphous drug-amino acid formulations provide dissolution advantage over crystalline drugs in both aqueous and biorelevant conditions. PMID:26373205

  3. Properties of a new acid-buffering bioadhesive vaginal formulation (ACIDFORM).

    PubMed

    Garg, S; Anderson, R A; Chany, C J; Waller, D P; Diao, X H; Vermani, K; Zaneveld, L J

    2001-07-01

    Vaginal prophylactic methodology may prevent heterosexual transmission of the HIV and other sexually transmitted disease-causing organisms as well as unplanned pregnancies. A new delivery system (ACIDFORM) was designed with acid-buffering, bioadhesive, and viscosity-retaining properties to (1) maintain the acidic vaginal milieu (the low pH inactivates many pathogens and spermatozoa), (2) form a protective layer over the vaginal/cervical epithelium (minimizing contact with pathogenic organisms), and (3) provide long-term vaginal retention. A Phase I clinical study with ACIDFORM provided initial information about its safety and showed the formation of a layer over the vaginal/cervical epithelium [1; Amaral et al., Contraception 1999;60:361-6]. To study the properties of the gel (without active ingredient) in more detail, ACIDFORM's acid-buffering, bioadhesive, viscosity-retaining, and spermicidal properties were compared in vitro to marketed formulations, and its long-term stability was assessed. ACIDFORM, either when titrated with NaOH or when mixed directly with semen, is highly acid buffering and much more effective than Aci-Jel, a commercial acid-buffering vaginal product. ACIDFORM adheres well to two model membranes (excised sheep vagina and cellophane) and is more bioadhesive than Conceptrol, Advantage S, Replens, Aci-Jel, and K-Y jelly. On dilution, ACIDFORM also retains its viscosity better than these marketed products. ACIDFORM is spermicidal and is stable for at least 2 years. These results suggest that ACIDFORM has advantages over presently marketed vaginal delivery systems. The gel may either be useful by itself as an antimicrobial contraceptive product or as a formulation vehicle for an active ingredient with antimicrobial and/or contraceptive properties. PMID:11535216

  4. Fluid transport by the cornea endothelium is dependent on buffering lactic acid efflux.

    PubMed

    Li, Shimin; Kim, Edward; Bonanno, Joseph A

    2016-07-01

    Maintenance of corneal hydration is dependent on the active transport properties of the corneal endothelium. We tested the hypothesis that lactic acid efflux, facilitated by buffering, is a component of the endothelial fluid pump. Rabbit corneas were perfused with bicarbonate-rich (BR) or bicarbonate-free (BF) Ringer of varying buffering power, while corneal thickness was measured. Perfusate was collected and analyzed for lactate efflux. In BF with no added HEPES, the maximal corneal swelling rate was 30.0 ± 4.1 μm/h compared with 5.2 ± 0.9 μm/h in BR. Corneal swelling decreased directly with [HEPES], such that with 60 mM HEPES corneas swelled at 7.5 ± 1.6 μm/h. Perfusate [lactate] increased directly with [HEPES]. Similarly, reducing the [HCO3 (-)] increased corneal swelling and decreased lactate efflux. Corneal swelling was inversely related to Ringer buffering power (β), whereas lactate efflux was directly related to β. Ouabain (100 μM) produced maximal swelling and reduction in lactate efflux, whereas carbonic anhydrase inhibition and an monocarboxylic acid transporter 1 inhibitor produced intermediate swelling and decreases in lactate efflux. Conversely, 10 μM adenosine reduced the swelling rate to 4.2 ± 0.8 μm/h and increased lactate efflux by 25%. We found a strong inverse relation between corneal swelling and lactate efflux (r = 0.98, P < 0.0001). Introducing lactate in the Ringer transiently increased corneal thickness, reaching a steady state (0 ± 0.6 μm/h) within 90 min. We conclude that corneal endothelial function does not have an absolute requirement for bicarbonate; rather it requires a perfusing solution with high buffering power. This facilitates lactic acid efflux, which is directly linked to water efflux, indicating that lactate flux is a component of the corneal endothelial pump. PMID:27225657

  5. A biogeochemical comparison of two well-buffered catchments with contrasting histories of acid deposition

    USGS Publications Warehouse

    Shanley, J.B.; Kram, P.; Hruska, J.; Bullen, T.D.

    2004-01-01

    Much of the biogeochemical cycling research in catchments in the past 25 years has been driven by acid deposition research funding. This research has focused on vulnerable base-poor systems; catchments on alkaline lithologies have received little attention. In regions of high acid loadings, however, even well-buffered catchments are susceptible to forest decline and episodes of low alkalinity in streamwater. As part of a collaboration between the Czech and U.S. Geological Surveys, we compared biogeochemical patterns in two well-studied, well-buffered catchments: Pluhuv Bor in the western Czech Republic, which has received high loading of atmospheric acidity, and Sleepers River Research Watershed in Vermont, U.S.A., where acid loading has been considerably less. Despite differences in lithology, wetness, forest type, and glacial history, the catchments displayed similar patterns of solute concentrations and flow. At both catchments, base cation and alkalinity diluted with increasing flow, whereas nitrate and dissolved organic carbon increased with increasing flow. Sulfate diluted with increasing flow at Sleepers River, while at Pluhuv Bor the sulfate-flow relation shifted from positive to negative as atmospheric sulfur (S) loadings decreased and soil S pools were depleted during the 1990s. At high flow, alkalinity decreased to near 100 ??eq L-1 at Pluhuv Bor compared to 400 ??eq L-1 at Sleepers River. Despite the large amounts of S flushed from Pluhuv Bor soils, these alkalinity declines were caused solely by dilution, which was greater at Pluhuv Bor relative to Sleepers River due to greater contributions from shallow flow paths at high flow. Although the historical high S loading at Pluhuv Bor has caused soil acidification and possible forest damage, it has had little effect on the acid/base status of streamwater in this well-buffered catchment. ?? 2004 Kluwer Academic Publishers.

  6. Acid-base buffering of soils in transitional and transitional-accumulative positions of undisturbed southern-taiga landscapes

    NASA Astrophysics Data System (ADS)

    Rusakova, E. S.; Ishkova, I. V.; Tolpeshta, I. I.; Sokolova, T. A.

    2012-05-01

    The method of continuous potentiometric titration (CPT) of soil water suspensions was used to evaluate the acid-base buffering of samples from the major genetic horizons of podzolic soils on a slope and soddy gley soils on the adjacent floodplain of a rivulet. In the soils of the slope, the buffering to acid upon titration from the pH of the initial titration point (ITP) to pH 3 in all the horizons was 1.5-2.0 times lower than that in the podzolic soils of the leveled interfluve, which could be due to the active leaching of exchangeable bases and oxalate-soluble aluminum and iron compounds with the later soil flows. In the soddy gley soils, the buffering to acid in the mineral horizons was 2-10 times higher than that in the podzolic soils. A direct dependence of the soil buffering to acid on the total content of exchangeable bases and on the content of oxalate-soluble aluminum compounds was found. A direct dependence of the buffering to basic upon titration from the ITP to pH 10 on the contents of the oxalate-soluble aluminum and organic matter was observed in the mineral horizons of all the studied soils. The soil treatment with Tamm's reagent resulted in the decrease of the buffering to acid in the soddy gley soils of the floodplain, as well as in the decrease of the buffering to basic in the soils on the slopes and in the soddy gley soils. It was also found that the redistribution of the mobile aluminum compounds between the eluvial, transitional, and transitional-accumulative positions in the undisturbed southern taiga landscapes leads to significant spatial differentiation of the acid-base buffering of the mineral soil horizons with a considerable increase in the buffer capacity of the soils within the transitional-accumulative terrain positions.

  7. Contributions of separate reactions to the acid-base buffering of soils in brook floodplains (Central Forest State Reserve)

    NASA Astrophysics Data System (ADS)

    Sokolova, T. A.; Tolpeshta, I. I.; Rusakova, E. S.

    2016-04-01

    The acid-base buffering of gleyic gray-humus soils developed in brook floodplains and undisturbed southern-taiga landscapes has been characterized by the continuous potentiometric titration of soil water suspensions. During the interaction with an acid, the major amount of protons (>80%) is consumed for the displacement of exchangeable bases and the dissolution of Ca oxalates. In the O and AY horizons, Mn compounds make the major contribution (2-15%) to the acid buffering. The buffer reactions with the participation of Al compounds make up from 0.5 to 1-2% of the total buffering capacity, and the protonation of the surface OH groups of kaolinite consumes 2-3% of the total buffering capacity. The deprotonation of OH groups on the surface of Fe hydroxides (9-43%), the deprotonation of OH groups on the surface of illite crystals (3-19%), and the dissolution of unidentified aluminosilicates (9-14%) are the most significant buffer reactions whose contributions have been quantified during the interaction with a base. The contribution of the deprotonation of OH groups on the surface of kaolinite particles is lower (1-5%) because of the small specific surface area of this mineral, and that of the dissolution of Fe compounds is insignificant. In the AY horizon, the acid and base buffering of soil in the rhizosphere is higher than beyond the rhizosphere because of the higher contents of organic matter and nonsilicate Fe and Al compounds.

  8. Plasma levels of acetylsalicylic acid and salicylic acid after oral ingestion of plain and buffered acetylsalicylic acid in relation to bleeding time and thrombocyte function.

    PubMed

    Proost, J H; Van Imhoff, G W; Wesseling, H

    1983-02-25

    Buffered acetylsalicylic acid (Alka Seltzer, B-ASA) and plain aspirin (P-ASA) tablets were compared as to their effects on bleeding time and platelet function in eight healthy male volunteers. Two doses (500 and 1000 mg) of each preparation were investigated in a cross-over design, each volunteer being his own control in each dose group (n=4). Both preparations disturbed platelet aggregation to the same extent. Bleeding time increased after both preparations, though significantly more after the buffered preparation than after plain acetylsalicylic acid, irrespective of the dosage. The 1000 mg dose prolonged bleeding time significantly more than the 500 mg dose, irrespective of the preparation. Kinetic analysis showed that B-ASA gave higher peak plasma levels of acetylsalicylic acid (ASA) and accordingly salicylic acid peak levels were also higher after the buffered preparation. It is concluded that B-ASA in equi-analgesic doses prolongs bleeding time more than the plain preparation. Since it is less agressive on the gastro-intestinal mucosa, its use may be advantageous in situations where acetylsalicylic acid induced loss of platelet aggregation is desired. However, the risk of prolonged bleeding--e.g. after tooth extractions--is probably higher after the buffered preparation. PMID:6844122

  9. Influence of amino acids, buffers, and ph on the γ-irradiation-induced degradation of alginates.

    PubMed

    Ulset, Ann-Sissel T; Mori, Hideki; Dalheim, Marianne Ø; Hara, Masayuki; Christensen, Bjørn E

    2014-12-01

    Alginate-based biomaterials and medical devices are commonly subjected to γ-irradiation as a means of sterilization, either in the dry state or the gel (hydrated) state. In this process the alginate chains degrade randomly in a dose-dependent manner, altering alginates' material properties. The addition of free radical scavenging amino acids such as histidine and phenylalanine protects the alginate significantly against degradation, as shown by monitoring changes in the molecular weight distributions using SEC-MALLS and determining the pseudo first order rate constants of degradation. Tris buffer (0.5 M), but not acetate, citrate, or phosphate buffers had a similar effect on the degradation rate. Changes in pH itself had only marginal effects on the rate of alginate degradation and on the protective effect of amino acids. Contrary to previous reports, the chemical composition (M/G profile) of the alginates, including homopolymeric mannuronan, was unaltered following irradiation up to 10 kGy. PMID:25412478

  10. Artificially MoO3 graded ITO anodes for acidic buffer layer free organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Lee, Hye-Min; Kim, Seok-Soon; Kim, Han-Ki

    2016-02-01

    We report characteristics of MoO3 graded ITO anodes prepared by a RF/DC graded sputtering for acidic poly(3,4-ethylene dioxylene thiophene):poly(styrene sulfonic acid) (PEDOT:PSS)-free organic solar cells (OSCs). Graded sputtering of the MoO3 buffer layer on top of the ITO layer produced MoO3 graded ITO anodes with a sheet resistance of 12.67 Ω/square, a resistivity of 2.54 × 10-4 Ω cm, and an optical transmittance of 86.78%, all of which were comparable to a conventional ITO anode. In addition, the MoO3 graded ITO electrode showed a greater work function of 4.92 eV than that (4.6 eV) of an ITO anode, which is beneficial for hole extraction from an organic active layer. Due to the high work function of MoO3 graded ITO electrodes, the acidic PEDOT:PSS-free OSCs fabricated on the MoO3 graded ITO electrode exhibited a power conversion efficiency 3.60% greater than that of a PEDOT:PSS-free OSC on the conventional ITO anode. The successful operation of PEDOT:PSS-free OSCs indicates simpler fabrication steps for cost-effective OSCs and elimination of interfacial reactions caused by the acidic PEDOT:PSS layer for reliable OSCs.

  11. An oral sodium citrate-citric acid non-particulate buffer in humans.

    PubMed

    Hauptfleisch, J J; Payne, K A

    1996-11-01

    We have investigated the effect on the pH of the gastric fluid of a single dose of sodium citrate 0.3 mol litre-1 (antacid) and a solution containing sodium citrate dehydrate (100 mg ml-1) with citric acid monohydrate (66 mg ml-1) (buffer). The dose for both solutions was 0.4 ml kg-1 via a nasogastric tube. Each group comprised 10 patients undergoing neurosurgical operations of 5-7 h duration. A control group of 10 patients received no gastric solution. The pH of the gastric aspirate was measured hourly using a Metrohm 632 digital pH meter (Synectics Medical, Sweden). Mean baseline gastric pH was 2.64 (SD 1.71). In the control group, pH increased to 4.4 (1.51) at 5 h, returning to baseline at 7 h. In the antacid group, pH increased to 6.11 (0.47) at 15 min and decreased to 3.70 (1.94) at 7 h (P < 0.01). In the buffer group, pH was stable at 3.80-3.95 (0.22) over 7 h (P > 0.01). Total mean gastric aspirate was 0.5 ml kg-1. PMID:8957982

  12. Responses of soil buffering capacity to acid treatment in three typical subtropical forests.

    PubMed

    Jiang, Jun; Wang, Ying-Ping; Yu, Mengxiao; Li, Kun; Shao, Yijing; Yan, Junhua

    2016-09-01

    Elevated anthropogenic acid deposition can significantly affect forest ecosystem functioning by changing soil pH, nutrient balance, and chemical leaching and so on. These effects generally differ among different forests, and the dominant mechanisms for those observed responses often vary, depending on climate, soil conditions and vegetation types. Using soil monoliths (0-40cm) from pine forest (pioneer), coniferous and broadleaved mixed forest (transitional) and broadleaved forest (mature) in southern China, we conducted a leaching experiment with acid treatments at different pH levels (control: pH≈4.5; pH=3.5; pH=2.5). We found that pH3.5 treatment significantly reduced dissolved organic carbon (DOC) concentrations in leachate from the pioneer forest soil. pH2.5 treatment significantly increased concentrations of NO3(-), SO4(2-), Ca(2+), Mg(2+), Al(3+), Fe(3+) and DOC in leachate from the pioneer forest soil, and also concentrations of NO3(-), SO4(2-), Mg(2+), Al(3+), Fe(3+) and DOC in leachate from the transitional forest soil. All acid treatments had no significant effects on concentrations of these chemicals in leachate from the mature forest soil. The responses can be explained by the changes in soil pH, acid neutralizing capacity (ANC) and concentrations of Al and Fe. Our results showed that acid buffering capacity of the pioneer or transitional forest soil was lower than that of the mature forest soil. Therefore preserving mature forests in southern China is important for reducing the adverse impacts of high acid deposition on stream water quality at present and into the future. PMID:27185346

  13. Separation of Trivalent Actinides from Lanthanides in an Acetate Buffer Solution Using Cyanex 301

    SciTech Connect

    Jack D. Law; Dean R. Peterman; Terry A. Todd; Richard D. Tillotson

    2006-05-01

    The separation of trivalent actinides from the lanthanides using the active extractant in the Cyanex 301 reagent, bis(2,4,4-trimethylpentyl)dithiophosphinic acid, was studied. Specifically, the extractant was studied for an ammonium acetate/acetic acid buffered feed that would result from a transuranic separation process utilizing an ammonium acetate strip solution. Separation factors of 241Am from 154Eu with this extractant, as a function of total acetate concentration and pH, have been measured. Additionally, the extraction behavior of stable La, Ce, Pr, Nd, Sm, and Eu was measured. Separation factors were typically very high for Am from Eu at a pH ranging from 3.8 to 5.8 and a total acetate concentration ranging from 0.2 M to 1.0 M. However, separation factors across the lanthanide series varied considerably and resulted in separation of the lighter lanthanides from the heavier lanthanides at the higher pH’s.

  14. Influence of solid-state acidity on the decomposition of sucrose in amorphous systems II (effect of buffer).

    PubMed

    Alkhamis, Khouloud A

    2009-04-01

    It was of interest to investigate the solid-state acidity using indicator probe molecules and sucrose degradation. Amorphous samples containing lactose, sucrose, buffers (citrate, malate, tartarate, or phosphate) with different pH values, and sodium chloride (to adjust the ionic strength) were prepared by freeze-drying. The lyophiles were characterized using powder X-ray diffraction, differential scanning calorimetry, and Karl Fischer titrimetry. The solid-state acidity of all lyophiles was measured using diffuse reflectance spectroscopy and suitable indicators (thymol blue or bromophenol blue). Selected lyophiles were subjected to a temperature of 60 degrees C and were analyzed for sucrose degradation using the Trinder kit. The results obtained from this study have shown that good correlation can be obtained between the solid-state acidity and the molar ratio of the salt and the acid in solution. The degradation of sucrose in the lyophiles is extremely sensitive to the solid-state acidity and might be able to provide a better estimate for the acidity than the indicator probe molecules. The Hammett acidity-rate profile for sucrose degradation in the lyophiles (using four different buffers) was also obtained. The profile showed similarity to the pH-rate profile in solution, and no buffer catalysis for sucrose degradation was detected in this study. PMID:19016102

  15. Separation of proteins and peptides by capillary electrophoresis in acid buffers containing high concentrations of surfactants.

    PubMed

    Miksík, I; Deyl, Z

    1999-08-01

    Separations of proteins at acid pH in the presence of a high concentration of surfactant [sodium laurylsulfate (SDS), 50 mmol/l] was investigated. The purpose of using high concentrations of SDS as background electrolyte modifier was threefold: First, the surfactant exerts a washing effect upon the capillary wall thus preventing binding of analytes and possible clogging of the capillary. Second, it was revealed that even under very acid conditions (below pH 3) the surfactant is capable of forming associates with protein analytes which still bear considerable negative charge and can be separated on this basis. Third, the system can be applied not only for protein mixtures sufficiently soluble in neutral to alkaline media (leukocyte lysates, standard proteins), but it can be used also with proteins, that are under such conditions virtually insoluble and their solubilization is possible in acid buffers only (eggshell proteins or collagen CNBr fragments). The result was that adsorption to the capillary wall was minimized and the analytes were separated as negatively charged associates with high efficiency. With collagen fragments partition was possible on the affinity differences of the peptides to the surfactant micelles and inner wall of the capillary. Theoretical plate counts approaching 100,000 were easily achieved even with proteins which under the more conventional operation conditions exhibit considerable sticking to the capillary wall. The other feature of this system is that the associates move very rapidly to the anode. Owing to the low pH, endoosmotic flow is negligible, and therefore the system has to be operated at reversed polarity. PMID:10480258

  16. Interference by Mes [2-(4-morpholino)ethanesulfonic acid] and related buffers with phenolic oxidation by peroxidase.

    PubMed

    Baker, C Jacyn; Mock, Norton M; Roberts, Daniel P; Deahl, Kenneth L; Hapeman, Cathleen J; Schmidt, Walter F; Kochansky, Jan

    2007-11-01

    While characterizing the kinetic parameters of apoplastic phenolic oxidation by peroxidase, we found anomalies caused by the Mes [2-(4-morpholino)ethanesulfonic acid] buffer being used. In the presence of Mes, certain phenolics appeared not to be oxidized by peroxidase, yet the oxidant, H(2)O(2), was utilized. This anomaly seems to be due to the recycling of the phenolic substrate. The reaction is relatively inefficient, but at buffer concentrations of 10 mM or greater the recycling effect is nearly 100% with substrate concentrations less than 100 microM. The recycling effect is dependent on substrate structure, occurring with 4'-hydroxyacetophenone but not with 3',5'-dimethoxy-4'-hydroxyacetophenone (acetosyringone). Characterization of the reaction parameters suggests that the phenoxyl radical from the peroxidase reaction interacts with Mes, causing the reduction and regeneration of the phenol. Similar responses occurred with related buffers such as Hepes [4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid] and Pipes [piperazine-1,4-bis(2-ethanesulfonic acid)]. Results from this work and other reports in the literature indicate that great care is required in interpreting any results involving these buffers under oxidizing conditions. PMID:17893045

  17. Buffering effects of calcium salts in kimchi: lowering acidity, elevating lactic acid bacterial population and dextransucrase activity.

    PubMed

    Chae, Seo Eun; Moon, Jin Seok; Jung, Jee Yun; Kim, Ji-Sun; Eom, Hyun-Ju; Kim, So-Young; Yoon, Hyang Sik; Han, Nam Soo

    2009-12-01

    This study investigates the buffering effects of calcium salts in kimchi on total acidity, microbial population, and dextransucrase activity. Calcium chloride or calcium carbonate was added in dongchimi-kimchi, a watery-radish kimchi, and their effects on various biochemical attributes were analyzed. The addition of 0.1% calcium chloride produced a milder decrease in the pH after 24 days of incubation, which allowed the lactic acid bacteria to survive longer than in the control. In particular, the heterofermentative Leuconostoc genus population was 10-fold higher than that in the control. When sucrose and maltose were also added along with the calcium salts, the dextransucrase activity in the kimchi was elevated and a higher concentration of isomaltooligosaccharides was synthesized when compared with the control. Calcium chloride was determined as a better activator compound of dextransucrase than calcium carbonate, probably because of its higher solubility. Therefore, the results of this study confirm the ability of the proposed approach to modulate the kimchi fermentation process and possibly enhance the quality of kimchi based on the addition of dietary calcium salts. PMID:20075632

  18. In situ ellipsometric investigation of stainless steel corrosion behavior in buffered solutions with amino acids

    NASA Astrophysics Data System (ADS)

    Vinnichenko, M. V.; Pham, M. T.; Chevolleau, T.; Poperenko, L. V.; Maitz, M. F.

    2003-02-01

    The corrosion of metals is associated both with a release of ions and changes in optical surface properties. In this study, these two effects were correlated by a potentiodynamic corrosion test and in situ probing of the surface by ellipsometry. The studies were carried out with stainless steel (SS) AISI 304 and 316 in phosphate buffered saline (PBS) and in Dulbecco's modified minimal essential medium (DMEM) at pH 7.4. In both media, 304 steel is more susceptible to corrosion than 316 grade. The 316 steel shows a higher corrosion potential and higher corrosion current density in PBS than in DMEM, for 304 steel this behavior is vice versa. Ellipsometry demonstrated a higher sensitivity than potentiodynamics to surface modification in the cathodic area. In DMEM the removal of a surface layer at negative potential and a further repassivation with increasing potential was characteristic. In PBS a surface layer started to grow immediately. X-ray photoelectron spectra of this layer formed in PBS are consistent with iron phosphate. Its formation is inhibited in DMEM; the presence of amino acids is discussed as the reason.

  19. The erosion kinetics of conventional and resin-modified glass-ionomer luting cements in acidic buffer solutions.

    PubMed

    Hazar-Yoruc, Binnaz; Bavbek, Andac Barkin; Özcan, Mutlu

    2012-01-01

    This study investigated the erosion kinetics of conventional and resin-modified glass-ionomer luting cements in acidic buffer solutions as a function of time. Disc shaped specimens were prepared from conventional (Ketac-Cem: KTC) and resin-modified glass ionomer cements (Fuji Plus: FP) and immersed in three acidic buffer solutions (0.01 M) namely, acetic acid/sodium acetate (AA(B)), lactic acid/sodium lactate (LA(B)) and citric acid/sodium citrate (CA(B)) with a constant pH of 4.1 and stored for 1, 8, 24, 48, 80, 120 and 168 h. F concentration was determined using ion-specific electrode. Si, Ca and Al concentrations were determined by atomic absorption spectroscopy. Ca, Al, Si and F solubility rates in both FP and KTC were the highest in CA(B) solution. The erosion rates of both FP and KTC in all buffer solutions increased as a function of immersion time. The amount of F eluted from FP was more than that of KTC. The total amount of elements released from FP was less than KTC in all solutions. PMID:23207217

  20. Influence of buffered and unbuffered acetylsalicylic acid on dental enamel and dentine in human teeth: an in vitro pilot study.

    PubMed

    Rogalla, K; Finger, W; Hannig, M

    1992-06-01

    An in vitro study was conducted to investigate the erosive effect of buffered and unbuffered acetylsalicylic acid (ASA) on dental enamel and dentine in human teeth by scanning electron microscopy. In order to standardize the specimens and to improve comparability the dental enamel and dentine were superficially abraded. The enamel and dentine specimens were therefore particularly sensitive to the influences of acid agents. Concentrated solution of buffered chewable ASA tablets (500 mg ASA and 300 mg calcium carbonate in 5 ml water) showed no changes in the enamel surface structure after exposure times of 1 min, 5 min and 60 min. In contrast, minimal corrosive effects were already seen after exposure of the enamel surface to the unbuffered ASA solutions for 1 min. After exposure times of 5 min and 60 min erosion of the enamel was more pronounced. Immersion in the unbuffered ASA solution led to clearly visible micromorphological changes on the dentine surfaces even after exposure for 1 min. Exposure of the dentine specimens to the buffered ASA solutions led to only very slight changes in the surface morphology. Therefore, the scanning electron micrograph after exposure to buffered ASA is comparable to the picture of untreated dentine. PMID:1513188

  1. In situ measurement of reaction volume and calculation of pH of weak acid buffer solutions under high pressure.

    PubMed

    Min, Stephen K; Samaranayake, Chaminda P; Sastry, Sudhir K

    2011-05-26

    Direct measurements of reaction volume, so far, have been limited to atmospheric pressure. This study describes a method for in situ reaction volume measurements under pressure using a variable volume piezometer. Reaction volumes for protonic ionization of weak acid buffering agents (MES, citric acid, sulfanilic acid, and phosphoric acid) were measured in situ under pressure up to 400 MPa at 25 °C. The methodology involved initial separation of buffering agents within the piezometer using gelatin capsules. Under pressure, the volume of the reactants was measured at 25 °C, and the contents were heated to 40 °C to dissolve the gelatin and allow the reaction to occur, and cooled to 25 °C, where the volume of products was measured. Reaction volumes were used to calculate pH of the buffer solutions as a function of pressure. The results show that the measured reaction volumes as well as the calculated pH values generally quite agree with their respective theoretically predicted values up to 100 MPa. The results of this study highlight the need for a comprehensive theory to describe the pressure behavior of ionization reactions in realistic systems especially at higher pressures. PMID:21542618

  2. In Vivo Predictive Dissolution: Comparing the Effect of Bicarbonate and Phosphate Buffer on the Dissolution of Weak Acids and Weak Bases.

    PubMed

    Krieg, Brian J; Taghavi, Seyed Mohammad; Amidon, Gordon L; Amidon, Gregory E

    2015-09-01

    Bicarbonate is the main buffer in the small intestine and it is well known that buffer properties such as pKa can affect the dissolution rate of ionizable drugs. However, bicarbonate buffer is complicated to work with experimentally. Finding a suitable substitute for bicarbonate buffer may provide a way to perform more physiologically relevant dissolution tests. The dissolution of weak acid and weak base drugs was conducted in bicarbonate and phosphate buffer using rotating disk dissolution methodology. Experimental results were compared with the predicted results using the film model approach of (Mooney K, Mintun M, Himmelstein K, Stella V. 1981. J Pharm Sci 70(1):22-32) based on equilibrium assumptions as well as a model accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . Assuming carbonic acid is irreversible in the dehydration direction: CO2 + H2 O ← H2 CO3 , the transport analysis can accurately predict rotating disk dissolution of weak acid and weak base drugs in bicarbonate buffer. The predictions show that matching the dissolution of weak acid and weak base drugs in phosphate and bicarbonate buffer is possible. The phosphate buffer concentration necessary to match physiologically relevant bicarbonate buffer [e.g., 10.5 mM (HCO3 (-) ), pH = 6.5] is typically in the range of 1-25 mM and is very dependent upon drug solubility and pKa . PMID:25980464

  3. Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films

    DOEpatents

    Hankins, Matthew G.

    2009-10-06

    Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

  4. The suitability of tris(hydroxylmethyl) aminomethane (THAM) as a buffering system for hydroxypropyl methylcellulose (HPMC) hydrophilic matrices containing a weak acid drug.

    PubMed

    Pygall, Samuel R; Kujawinski, Sarah; Timmins, Peter; Melia, Colin D

    2010-03-15

    There are few studies of alkalising pH-modifiers in HPMC hydrophilic matrices. These agents may be incorporated to provide microenvironmental buffering and facilitate pH-independent release of weak acid drugs. This study compared tris(hydroxylmethyl) aminomethane (THAM, TRIS, tromethamine, trometamol) with sodium citrate as internal buffering agents for HPMC (4000 cps) 2208 and 2910 matrices containing felbinac, a weak acid drug which exhibits pH-dependent solubility. Drug release at pH 1.2 and 7.5 was accelerated by both buffers, but THAM-buffered matrices provided extended, diffusion-based release kinetics, without loss of matrix integrity at high buffer concentrations. Release kinetics appeared to be independent of media pH. THAM did not depress the sol-gel transition temperature or suppress HPMC particle swelling, and had minimal effects on gel layer formation. Sodium citrate promoted greater thickness of the early gel layer than THAM. Measurements of internal gel layer pH showed that both buffers produced a rapid alkalisation of the gel layer which was progressively lost. As result of its higher pK(a) and molar ratio on a percent weight basis, THAM provided a higher internal pH and a greater longevity of pH modification. It is concluded that THAM offers a useful buffering option for weak acid drugs in HPMC-based systems. PMID:20005935

  5. The acid-base buffer capacity of podzolic soils and its changes under the impact of treatment with the Mehra-Jackson and Tamm reagents

    NASA Astrophysics Data System (ADS)

    Maksimova, Yu. G.; Maryakhina, N. N.; Tolpeshta, I. I.; Sokolova, T. A.

    2010-10-01

    The acid-base buffer capacity before and after the treatment with the Mehra-Jackson and Tamm reagents was assessed by continuous potentiometric titration for the main genetic horizons of two profiles of podzolic soils in the Central Forest State Reserve. The total buffer capacity was calculated in the pH range from the initial titration point (ITP) to 3 for the acid titration and from the ITP to 10 for the base titration, as well as the buffer capacities in the pH intervals of 0.25. It was found that both treatments abruptly decreased the base buffer capacity, which reached 70-90% in the E horizons. The high direct linear correlation of the difference between the total base buffer capacities before and after each treatment with the content of Fe in the Tamm extract was revealed. From the results obtained, a conclusion was drawn that finely dispersed Fe hydroxides were the main solid-phase constituents ensuring the base buffer capacity, and the deprotonation of hydroxyl groups on the surface of Fe hydroxides was the essential buffer reaction during the base titration.

  6. Acidification and buffering mechanisms in acid sulfate soil wetlands of the Murray-Darling Basin, Australia.

    PubMed

    Glover, Fiona; Whitworth, Kerry L; Kappen, Peter; Baldwin, Darren S; Rees, Gavin N; Webb, John A; Silvester, Ewen

    2011-04-01

    The acid generation mechanisms and neutralizing capacities of sulfidic sediments from two inland wetlands have been studied in order to understand the response of these types of systems to drying events. The two systems show vastly different responses to oxidation, with one (Bottle Bend (BB) lagoon) having virtually no acid neutralizing capacity (ANC) and the other (Psyche Bend (PB) lagoon) an ANC that is an order of magnitude greater than the acid generation potential. While BB strongly acidifies during oxidation the free acid generation is less than that expected from the measured proton production and consumption processes, with additional proton consumption attributed to the formation of an acid-anion (chloride) FeIII (oxyhydr)oxide product, similar to akaganéite (Fe(OH)2.7Cl0.3). While such products can partially attenuate the acidification of these systems, resilience to acidification is primarily imparted by sediment ANC. PMID:21375259

  7. An investigation using atomic force microscopy nanoindentation of dental enamel demineralization as a function of undissociated acid concentration and differential buffer capacity

    NASA Astrophysics Data System (ADS)

    Barbour, Michele E.; Shellis, R. Peter

    2007-02-01

    Acidic drinks and foodstuffs can demineralize dental hard tissues, leading to a pathological condition known as dental erosion, which is of increasing clinical concern. The first step in enamel dissolution is a demineralization of the outer few micrometres of tissue, which results in a softening of the structure. The primary determinant of dissolution rate is pH, but the concentration of undissociated acid, which is related to buffer capacity, also appears to be important. In this study, atomic force microscopy nanoindentation was used to measure the first initial demineralization (softening) induced within 1 min by exposure to solutions with a range of undissociated acid concentration and natural pH of 3.3 or with an undissociated acid concentration of 10 mmol l-1 and pH adjusted to 3.3. The results indicate that differential buffering capacity is a better determinant of softening than undissociated acid concentration. Under the conditions of these experiments, a buffer capacity of >3 mmol l-1 pH-1 does not have any further effect on dissolution rate. These results imply that differential buffering capacity should be used for preference over undissociated acid concentration or titratable acidity, which are more commonly employed in the literature.

  8. An exploratory study into students' conceptual understanding of acid/base principles associated with chemical buffer systems

    NASA Astrophysics Data System (ADS)

    MacGowan, Catherine Elizabeth

    The overall objective of this research project was to provide an insight into students' conceptual understanding of acid/base principles as it relates to the comprehension and correct application of scientific concepts during a problem-solving activity. The difficulties experienced learning science and in developing appropriate problem-solving strategies most likely are predetermined by students' existing conceptual and procedural knowledge constructs; with the assimilation of newly acquired knowledge hindering or aiding the learning process. Learning chemistry requires a restructuring of content knowledge which will allow the individual to assemble and to integrate his/her own perception of science with instructional knowledge. The epistemology of constructivism, the theoretical grounding for this research project, recognizes the student's role as an active participant in the learning process. The study's design was exploratory in nature and descriptive in design. The problem-solving activity, the preparation of a chemical buffer solution at pH of 9, was selected and modified to reflect and meet the study's objective. Qualitative research methods (i.e., think aloud protocols, retrospective interviews, survey questionnaires such as the Scale of Intellectual Development (SID), and archival data sources) were used in the collection and assessment of data. Given its constructivist grounding, simplicity, and interpretative view of knowledge acquisition and learning of collegiate aged individuals, the Perry Intellectual and Ethical Development Model (1970) was chosen as the applied model for evaluation student cognition. The study's participants were twelve traditional college age students from a small, private liberal arts college. All participants volunteered for the project and had completed or were completing a general college chemistry course at the time of the project. Upon analysis of the data the following observations and results were noted: (1) students

  9. PH BUFFERING IN FOREST SOIL ORGANIC HORIZONS: RELEVANCE TO ACID PRECIPITATION

    EPA Science Inventory

    Samples of organic surface horizons (Oi, Oe, Oa) from New York State forest soils were equilibrated with 0 to 20 cmol HNO3 Kg(-1) soil in the laboratory by a batch technique designed to simulate reactions of acid precipitation with forest floors. Each organic horizon retained a c...

  10. An evaluation of MES (2(N-Morpholino)ethanesulfonic acid) and Amberlite IRC-50 as pH buffers for nutrient solution studies

    NASA Technical Reports Server (NTRS)

    Bugbee, B. G.; Salisbury, F. B.

    1985-01-01

    All buffering agents used to stabilize pH in hydroponic research have disadvantages. Inorganic buffers are absorbed and may become phytotoxic. Solid carbonate salts temporarily mitigate decreasing pH but provide almost no protection against increasing pH, and they alter nutrient absorption. Exchange resins are more effective, but we find that they remove magnesium and manganese from solution. We have tested 2(N-Morpholino)ethanesulfonic acid (MES) as a buffering agent at concentrations of 1 and 10 mol m-3 (1 and 10 mM) with beans, corn, lettuce, tomatoes, and wheat. MES appears to be biologically inert and does not interact significantly with other solution ions. Relative growth rates among controls and MES treatments were nearly identical for each species during the trial period. The pH was stabilized by 1 mol m-3 MES. This buffer warrants further consideration in nutrient research.

  11. An evaluation of MES (2(N-Morpholino)ethanesulfonic acid) and Amberlite IRC-50 as pH buffers for nutrient solution studies.

    PubMed

    Bugbee, B G; Salisbury, F B

    1985-01-01

    All buffering agents used to stabilize pH in hydroponic research have disadvantages. Inorganic buffers are absorbed and may become phytotoxic. Solid carbonate salts temporarily mitigate decreasing pH but provide almost no protection against increasing pH, and they alter nutrient absorption. Exchange resins are more effective, but we find that they remove magnesium and manganese from solution. We have tested 2(N-Morpholino)ethanesulfonic acid (MES) as a buffering agent at concentrations of 1 and 10 mol m-3 (1 and 10 mM) with beans, corn, lettuce, tomatoes, and wheat. MES appears to be biologically inert and does not interact significantly with other solution ions. Relative growth rates among controls and MES treatments were nearly identical for each species during the trial period. The pH was stabilized by 1 mol m-3 MES. This buffer warrants further consideration in nutrient research. PMID:11539688

  12. Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions

    USGS Publications Warehouse

    Iggy, Litaor M.; Thurman, E.M.

    1988-01-01

    Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

  13. Effect of HEPES buffer on the uptake and transport of P-glycoprotein substrates and large neutral amino acids

    PubMed Central

    Luo, Shuanghui; Pal, Dhananjay; Shah, Sujay J.; Kwatra, Deep; Paturi, Kalyani D.; Mitra, Ashim. K.

    2010-01-01

    HEPES has been widely employed as an organic buffer agent in cell culture medium as well as uptake and transport experiments in vitro. However, concentrations of HEPES used in such studies vary from one laboratory to another. In this study, we investigated the effect of HEPES on the uptake and bidirectional transport of P-gp substrates employing both Caco-2 and MDCK-MDR1 cells. ATP-dependent uptake of glutamic acid was also examined. ATP production was further quantified applying ATP Determination Kit. An addition of HEPES to the cellular washing and incubation media significantly altered the uptake and transport of P-gp substrates in both Caco-2 and MDCK-MDR1 cells. Uptake of P-gp substrates substantially diminished as the HEPES concentration was raised to 25 mM. Bidirectional (A-B and B-A) transport studies revealed that permeability ratio of PappB-A to PappA-B in the presence of 25 mM HEPES was significantly higher than control. The uptake of phenylalanine is an ATP-independent process, whereas the accumulation of glutamic acid is ATP-dependent. While phenylalanine uptake remained unchanged glutamic acid uptake was elevated with the addition of HEPES. Verapamil is an inhibitor of P-gp mediated uptake, elevation of cyclosporine uptake in the presence of 5 μM verapamil was compromised by the presence of 25 mM HEPES. The results of ATP assay indicated that HEPES stimulated the production of ATP. This study suggests that the addition of HEPES in the medium modulated the energy dependent efflux and uptake processes. The effect of HEPES on P-gp mediated drug efflux and transport may provide some mechanistic insight into possible reasons for inconsistencies in the results reported from various laboratories. PMID:20163160

  14. Comparative Evaluation of Shear Bond Strength of Luting Cements to Different Core Buildup Materials in Lactic Acid Buffer Solution

    PubMed Central

    Patil, Siddharam M.; Desai, Raviraj G.; Arabbi, Kashinath C.; Prakash, Ved

    2015-01-01

    Aim and Objectives The core buildup material is used to restore badly broken down tooth to provide better retention for fixed restorations. The shear bond strength of a luting agent to core buildup is one of the crucial factors in the success of the cast restoration. The aim of this invitro study was to evaluate and compare the shear bond strength of luting cements with different core buildup materials in lactic acid buffer solution. Materials and Methods Two luting cements {Traditional Glass Ionomer luting cement (GIC) and Resin Modified Glass Ionomer luting cement (RMGIC)} and five core buildup materials {Silver Amalgam, Glass ionomer (GI), Glass Ionomer Silver Reinforced (GI Silver reinforced), Composite Resin and Resin Modified Glass Ionomer(RMGIC)} were selected for this study. Total 100 specimens were prepared with 20 specimens for each core buildup material using a stainless steel split metal die. Out of these 20 specimens, 10 specimens were bonded with each luting cement. All the bonded specimens were stored at 370c in a 0.01M lactic acid buffer solution at a pH of 4 for 7days. Shear bond strength was determined using a Universal Testing Machine at a cross head speed of 0.5mm/min. The peak load at fracture was recorded and shear bond strength was calculated. The data was statistically analysed using Two-way ANOVA followed by HOLM-SIDAK method for pair wise comparison at significance level of p<0.05. Results Two-Way ANOVA showed significant differences in bond strength of the luting cements (p<0.05) and core materials (p<0.05) and the interactions (p<0.05). Pairwise comparison of luting cements by HOLM-SIDAK test, showed that the RMGIC luting cement had higher shear bond strength values than Traditional GIC luting cement for all the core buildup materials. RMGIC core material showed higher bond strength values followed by Composite resin, GI silver reinforced, GI and silver amalgam core materials for both the luting agents. Conclusion Shear bond strength of

  15. Controlled release of acidic drugs in compendial and physiological hydrogen carbonate buffer from polymer blend-coated oral solid dosage forms.

    PubMed

    Wulff, R; Rappen, G-M; Koziolek, M; Garbacz, G; Leopold, C S

    2015-09-18

    The objective of this study was to investigate the suitability of "Eudragit® RL/Eudragit® L55" (RL/L55) blend coatings for a pH-independent release of acidic drugs. A coating for ketoprofen and naproxen mini tablets was developed showing constant drug release rate under pharmacopeial two-stage test conditions for at least 300 min. To simulate drug release from the mini tablets coated with RL/L55 blends in the gastrointestinal (GI) tract, drug release profiles in Hanks buffer pH 6.8 were recorded and compared with drug release profiles in compendial media. RL/L55 blend coatings showed increased drug permeability in Hanks buffer pH 6.8 compared to phosphate buffer pH 6.8 due to its higher ion concentration. However, drug release rates of acidic drugs were lower in Hanks buffer pH 6.8 because of the lower buffer capacity resulting in reduced drug solubility. Further dissolution tests were performed in Hanks buffer using pH sequences simulating the physiological pH conditions in the GI tract. Drug release from mini tablets coated with an RL/L55 blend (8:1) was insensitive to pH changes of the medium within the pH range of 5.8-7.5. It was concluded that coatings of RL/L55 blends show a high potential for application in coated oral drug delivery systems with a special focus on pH-independent release of acidic drugs. PMID:26093053

  16. Thermodynamic characteristics of molecular interactions between L-tryptophan and nicotinic acid and uracyl in aqueous buffer solutions at 298 K

    NASA Astrophysics Data System (ADS)

    Badelin, V. G.; Tyunina, E. Yu.; Mezhevoi, I. N.; Tarasova, G. N.

    2015-12-01

    The interaction between L-tryptophan (Trp) and nicotinic acid (NA) and uracyl (Ur) in aqueous buffer solutions (pH 7.35) at different ratios of reagents is studied via the calorimetry of dissolution. The enthalpies of dissolution of the amino acid in the buffer solutions of the ligands at 298.15 K are obtained. The stoichiometric compositions of the complexes being formed and binding constants have been determined. The values of the thermodynamic characteristics for the complex formation of L-tryptophan with nicotinic acid and uracyl are calculated. It is shown that the formation of molecular complexes with 1 : 2 composition is stabilized by the entropy factor for the Trp-NA system, and by the enthalpy factor for the Trp-Ur system.

  17. Buffer Therapy for Cancer.

    PubMed

    Ribeiro, Maria de Lourdes C; Silva, Ariosto S; Bailey, Kate M; Kumar, Nagi B; Sellers, Thomas A; Gatenby, Robert A; Ibrahim-Hashim, Arig; Gillies, Robert J

    2012-08-15

    Oral administration of pH buffers can reduce the development of spontaneous and experimental metastases in mice, and has been proposed in clinical trials. Effectiveness of buffer therapy is likely to be affected by diet, which could contribute or interfere with the therapeutic alkalinizing effect. Little data on food pH buffering capacity was available. This study evaluated the pH and buffering capacity of different foods to guide prospective trials and test the effect of the same buffer (lysine) at two different ionization states. Food groups were derived from the Harvard Food Frequency Questionnaire. Foods were blended and pH titrated with acid from initial pH values until 4.0 to determine "buffering score", in mmol H(+)/pH unit. A "buffering score" was derived as the mEq H(+) consumed per serving size to lower from initial to a pH 4.0, the postprandial pH of the distal duodenum. To differentiate buffering effect from any metabolic byproduct effects, we compared the effects of oral lysine buffers prepared at either pH 10.0 or 8.4, which contain 2 and 1 free base amines, respectively. The effect of these on experimental metastases formation in mice following tail vein injection of PC-3M prostate cancer cells were monitored with in vivo bioluminescence. Carbohydrates and dairy products' buffering score varied between 0.5 and 19. Fruits and vegetables showed a low to zero buffering score. The score of meats varied between 6 and 22. Wine and juices had negative scores. Among supplements, sodium bicarbonate and Tums(®) had the highest buffering capacities, with scores of 11 and 20 per serving size, respectively. The "de-buffered" lysine had a less pronounced effect of prevention of metastases compared to lysine at pH 10. This study has demonstrated the anti-cancer effects of buffer therapy and suggests foods that can contribute to or compete with this approach to manage cancer. PMID:24371544

  18. Buffer Therapy for Cancer

    PubMed Central

    Ribeiro, Maria de Lourdes C; Silva, Ariosto S.; Bailey, Kate M.; Kumar, Nagi B.; Sellers, Thomas A.; Gatenby, Robert A.; Ibrahim-Hashim, Arig; Gillies, Robert J.

    2013-01-01

    Oral administration of pH buffers can reduce the development of spontaneous and experimental metastases in mice, and has been proposed in clinical trials. Effectiveness of buffer therapy is likely to be affected by diet, which could contribute or interfere with the therapeutic alkalinizing effect. Little data on food pH buffering capacity was available. This study evaluated the pH and buffering capacity of different foods to guide prospective trials and test the effect of the same buffer (lysine) at two different ionization states. Food groups were derived from the Harvard Food Frequency Questionnaire. Foods were blended and pH titrated with acid from initial pH values until 4.0 to determine “buffering score”, in mmol H+/pH unit. A “buffering score” was derived as the mEq H+ consumed per serving size to lower from initial to a pH 4.0, the postprandial pH of the distal duodenum. To differentiate buffering effect from any metabolic byproduct effects, we compared the effects of oral lysine buffers prepared at either pH 10.0 or 8.4, which contain 2 and 1 free base amines, respectively. The effect of these on experimental metastases formation in mice following tail vein injection of PC-3M prostate cancer cells were monitored with in vivo bioluminescence. Carbohydrates and dairy products’ buffering score varied between 0.5 and 19. Fruits and vegetables showed a low to zero buffering score. The score of meats varied between 6 and 22. Wine and juices had negative scores. Among supplements, sodium bicarbonate and Tums® had the highest buffering capacities, with scores of 11 and 20 per serving size, respectively. The “de-buffered” lysine had a less pronounced effect of prevention of metastases compared to lysine at pH 10. This study has demonstrated the anti-cancer effects of buffer therapy and suggests foods that can contribute to or compete with this approach to manage cancer. PMID:24371544

  19. A nitrilo-tri-acetic-acid/acetic acid route for the deposition of epitaxial cerium oxide films as high temperature superconductor buffer layers

    SciTech Connect

    Thuy, T.T.; Lommens, P.; Narayanan, V.; Van de Velde, N.; De Buysser, K.; Herman, G.G.; Cloet, V.; Van Driessche, I.

    2010-09-15

    A water based cerium oxide precursor solution using nitrilo-tri-acetic-acid (NTA) and acetic acid as complexing agents is described in detail. This precursor solution is used for the deposition of epitaxial CeO{sub 2} layers on Ni-5at%W substrates by dip-coating. The influence of the complexation behavior on the formation of transparent, homogeneous solutions and gels has been studied. It is found that ethylenediamine plays an important role in the gelification. The growth conditions for cerium oxide films were Ar-5% gas processing atmosphere, a solution concentration level of 0.25 M, a dwell time of 60 min at 900 {sup o}C and 5-30 min at 1050 {sup o}C. X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM), pole figures and spectroscopic ellipsometry were used to characterize the CeO{sub 2} films with different thicknesses. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) was used to determine the carbon residue level in the surface of the cerium oxide film, which was found to be lower than 0.01%. Textured films with a thickness of 50 nm were obtained. - Graphical abstract: Study of the complexation and hydrolysis behavior of Ce{sup 4+} ions in the presence of nitrilo-tri-acetic acid and the subsequent development of an aqueous chemical solution deposition route suited for the processing of textured CeO{sub 2} buffer layers on Ni-W tapes.

  20. Explaining the Spatial Variability in Stream Acid Buffering Chemistry and Aquatic Biota in the Neversink River Watershed, Catskill Mountains, New York State

    NASA Astrophysics Data System (ADS)

    Harpold, A. A.; Walter, M. T.

    2009-12-01

    The Neversink River Watershed (NRW) originates at the highest point in the Catskill Mountains and is sensitive to changing patterns in acidic deposition, precipitation, and air temperature. Despite reductions in fossil fuel emission since the Clean Air Act, past acidic deposition has accelerated the leaching of cations from the soil and reduced the stores of base cations necessary for buffering stream acidity. The goal of this study was to investigate connections between different watershed ‘features’ and the apparently complex spatial patterns of stream buffering chemistry (specifically, acid neutralizing capacity ANC and Ca concentrations) and aquatic biota (macroinvertebrate and fish populations). The ten nested NRW watersheds (2.0 km^2 to 176.0 km^2) have relatively homogeneous bedrock geology, forested cover, and soil series; therefore, we hypothesized that differing distributions of hydrological flowpaths between the watersheds control the variability in stream buffering chemistry and aquatic biota. However because the flowpath distributions are not directly measurable, this study used step-wise linear regression to develop relationships between watershed ‘features’ and buffering chemistry. The regression results showed that the mean ratio of precipitation to stream runoff (or runoff ratio) from twenty non-winter storm events explained more than 81% of the variability in mean summer ANC and Ca concentrations. The results also suggested that steeper (higher mean slope) more channelized watersheds (larger drainage density) are more susceptible to stream acidity and negative impacts on biota. A simple linear relationship (using no discharge or water chemistry measurements) was able to explain buffering chemistry and aquatic biota populations in 17 additional NRW watersheds (0.3 km^2 to 160.0 km^2), including 60-80% of the variability in macroinvertebrate populations (EPT richness and BAP) and 50-60% of the variability in fish density and species richness

  1. Iron buffer system in the water column and partitioning in the sediments of the naturally acidic Lake Caviahue, Neuquén, Argentina

    NASA Astrophysics Data System (ADS)

    Cabrera, J. M.; Diaz, M. M.; Schultz, S.; Temporetti, P.; Pedrozo, F.

    2016-05-01

    Sedimentary iron partitioning was studied for five sediment strata (16 cm depth) at three sampling sites of the naturally-occurring acidic Lake Caviahue (Patagonia, Argentina). Additionally, water column iron was modeled based on five-year period input loadings to study a possible iron buffer system. The partition coefficient between the water column and the total iron content of the sediments was also addressed. Sedimentary iron was found to be distributed, on average, in the following forms: exchangeable (6%), iron oxides (4%), pyrite and reactive organic matter (38%) and residual (non-andesitic) materials with a high content of humic acids (52%). Furthermore, we found that the dissolved iron in the lake was nearly constant throughout the five year period we studied. This is consistent with the existence of an iron buffer system in the lake at pH between 2.0 and 3.0, which may cause differential iron precipitation at the delta of the volcanic river with respect to the deeper northern and southern arms. Sedimentary iron measurements taken at the delta further support the existence of a buffer system, where it was found that the iron content in the sub-superficial stratum (2 cm) was double that of the remainder of the vertical profile at the same site.

  2. Buffer Biology.

    ERIC Educational Resources Information Center

    Morgan, Kelly

    2000-01-01

    Presents a science experiment in which students test the buffering capacity of household products such as shampoo, hand lotion, fizzies candy, and cola. Lists the standards addressed in this experiment and gives an example of a student lab write-up. (YDS)

  3. The effects of secular calcium and magnesium concentration changes on the thermodynamics of seawater acid/base chemistry: Implications for Eocene and Cretaceous ocean carbon chemistry and buffering

    NASA Astrophysics Data System (ADS)

    Hain, Mathis P.; Sigman, Daniel M.; Higgins, John A.; Haug, Gerald H.

    2015-05-01

    Reconstructed changes in seawater calcium and magnesium concentration ([Ca2+], [Mg2+]) predictably affect the ocean's acid/base and carbon chemistry. Yet inaccurate formulations of chemical equilibrium "constants" are currently in use to account for these changes. Here we develop an efficient implementation of the MIAMI Ionic Interaction Model to predict all chemical equilibrium constants required for carbon chemistry calculations under variable [Ca2+] and [Mg2+]. We investigate the impact of [Ca2+] and [Mg2+] on the relationships among the ocean's pH, CO2, dissolved inorganic carbon (DIC), saturation state of CaCO3 (Ω), and buffer capacity. Increasing [Ca2+] and/or [Mg2+] enhances "ion pairing," which increases seawater buffering by increasing the concentration ratio of total to "free" (uncomplexed) carbonate ion. An increase in [Ca2+], however, also causes a decline in carbonate ion to maintain a given Ω, thereby overwhelming the ion pairing effect and decreasing seawater buffering. Given the reconstructions of Eocene [Ca2+] and [Mg2+] ([Ca2+]~20 mM; [Mg2+]~30 mM), Eocene seawater would have required essentially the same DIC as today to simultaneously explain a similar-to-modern Ω and the estimated Eocene atmospheric CO2 of ~1000 ppm. During the Cretaceous, at ~4 times modern [Ca2+], ocean buffering would have been at a minimum. Overall, during times of high seawater [Ca2+], CaCO3 saturation, pH, and atmospheric CO2 were more susceptible to perturbations of the global carbon cycle. For example, given both Eocene and Cretaceous seawater [Ca2+] and [Mg2+], a doubling of atmospheric CO2 would require less carbon addition to the ocean/atmosphere system than under modern seawater composition. Moreover, increasing seawater buffering since the Cretaceous may have been a driver of evolution by raising energetic demands of biologically controlled calcification and CO2 concentration mechanisms that aid photosynthesis.

  4. Contribution of light scattering to the circular dichroism of deoxyribonucleic acid films, deoxyribonucleic acid-polylysine complexes, and deoxyribonucleic acid particles in ethanolic buffers

    SciTech Connect

    Maestre, M.F.; Reich, C.

    1980-01-01

    The contribution of scattering to the circular dichroism (CD) of DNA films with twisted structures, DNA-polylysine complexes, and condensed DNA aggregates in ethanolic buffers of defined salt concentrations has been studied by the use of novel measuring techniques. These techniques include fluorscat cuvettes, fluorescence-detected circular dichroism (FDCD) methods, backscattering capturing devices, and beam-mounted goniometer detectors. The result of the experimental measurement is that DNA films can be made which have very large ellipticities or CD at sharp specific wavelengths. The sign of these ellipticities is related to the handedness of the twists, with a right-handed twist producing large positive rotations and a left-handed one producing negative rotations. The film shows nodal angles at which the interaction with light is minimal. The scattering patterns of both films, DNA-polylysine particles and DNA-EtOH condensates, show that the main interaction is light scattering produced by a resonance phenomenon similar to that produced in cholestric liquid crystals and twisted-nematic liquid crystals. It is proposed that the so-called psi-type CD spectrum is a manifestation of a side-by-side packing of DNA molecules with a long-range twisting order whose helical parameters match the helical parameter of circularly polarized light at specific resonance or critical wavelengths. Application of the Bragg law for cholesteric liquid crystals gives the periodicity of the long-range ordered structures. 9 figures.

  5. Efficiency of buffered aqueous carboxylic acid solutions and organic solvents to absorb SO/sub 2/ from industrial flue gas; solubility data from gas-liquid chromatography

    SciTech Connect

    Sanza, G.J.

    1982-01-01

    Nine adsorbents were examined. These potential candidates for flue gas desulfurization included 1-methyl-2-pyrrolidinone, tri-n-butyl phosphate (TBP), both 0.5 M and 1.0 M solutions of citric acid and glycolic acid, buffered to pH's of 4.5 and 3.8, and pure water. Infinite dilution activity coefficients of SO/sub 2/ were obtained by gas-liquid chromatography in a trial solvent of Nitrobenzene, and then in systems of 1-methyl-2-pyrrolidinone and TBP, independently. The solubility data of SO/sub 2/ was derived and found to be comparable to data obtained from a classical bubble-sparger apparatus. Solubility data was then programmed into an absorber-stripper computer simulator in order to calculate the various concentration and temperature profiles that would exist, the degree of desulfurization, and the steam consumption for all nine systems. Concentrated solutions of citric acid buffered to a low pH exhibited the most favorable conditions for application in direct steam regeneration processes. 1-methyl-2-pyrrolidinone yielded better performance than TBP did with high-pressure indirect steam used for stripping. Comparison between the aqueous solution systems which employed direct steam, and the organic systems which used indirect steam was inconclusive.

  6. Buffer capacity of biologics--from buffer salts to buffering by antibodies.

    PubMed

    Karow, Anne R; Bahrenburg, Sven; Garidel, Patrick

    2013-01-01

    Controlling pH is essential for a variety of biopharmaceutical process steps. The chemical stability of biologics such as monoclonal antibodies is pH-dependent and slightly acidic conditions are favorable for stability in a number of cases. Since control of pH is widely provided by added buffer salts, the current study summarizes the buffer characteristics of acetate, citrate, histidine, succinate, and phosphate buffers. Experimentally derived values largely coincide with values calculated from a model that had been proposed in 1922 by van Slyke. As high concentrated protein formulations become more and more prevalent for biologics, the self-buffering potential of proteins becomes of relevance. The current study provides information on buffer characteristics for pH ranges down to 4.0 and up to 8.0 and shows that a monoclonal antibody at 50 mg/mL exhibits similar buffer capacity as 6 mM citrate or 14 mM histidine (pH 5.0-6.0). Buffer capacity of antibody solutions scales linearly with protein concentration up to more than 200 mg/mL. At a protein concentration of 220 mg/mL, the buffer capacity resembles the buffer capacity of 30 mM citrate or 50 mM histidine (pH 5.0-6.0). The buffer capacity of monoclonal antibodies is practically identical at the process relevant temperatures 5, 25, and 40°C. Changes in ionic strength of ΔI=0.15, in contrast, can alter the buffer capacity up to 35%. In conclusion, due to efficient self-buffering by antibodies in the pH range of favored chemical stability, conventional buffer excipients could be dispensable for pH stabilization of high concentrated protein solutions. PMID:23296746

  7. Combined use of l-alanine tert butyl ester lactate and trimethyl-β-cyclodextrin for the enantiomeric separations of 2-arylpropionic acids nonsteroidal anti-inflammatory drugs.

    PubMed

    Mavroudi, Maria C; Kapnissi-Christodoulou, Constantina P

    2015-10-01

    In this study, a new CE method, employing a binary system of trimethyl-β-CD (TM-β-CD) and a chiral amino acid ester-based ionic liquid (AAIL), was developed for the chiral separation of seven 2-arylpropionic acid nonsteroidal anti-inflammatory drugs (NSAIDs). In particular, the enantioseparation of ibuprofen, ketoprofen, carprofen, indoprofen, flurbiprofen, naproxen, and fenoprofen was improved significantly by supporting the BGE with the chiral AAIL l-alanine tert butyl ester lactate (l-AlaC4 Lac). Parameters, such as concentrations of TM-β-CD and l-AlaC4 Lac, and buffer pH, were systematically examined in order to optimize the chiral separation of each NSAID. It was observed that the addition of the AAIL into the BGE improved both resolution and efficiency significantly. After optimization of separation conditions, baseline separation (Rs >1.5) of five of the analytes was achieved in less than 11 min, while the resolution of ibuprofen and flurbiprofen was approximately 1.2. The optimized enantioseparation conditions for all analytes involve a BGE of 5 mM sodium acetate/acetic acid (pH 5.0), an applied voltage of 30 kV, and a temperature of 20°C. In addition, the results obtained by computing the %-RSD values of the EOF and the two enantiomer peaks, demonstrated excellent run-to-run, batch-to-batch, and day-to-day reproducibilities. PMID:26080944

  8. Airborne soil dust and its importance in buffering of atmospheric acidity and critical load assessment, over the semi arid tract of northern India.

    NASA Astrophysics Data System (ADS)

    Sharma, Disha; Kulshrestha, Umesh

    Airborne soil dust and its importance in buffering of atmospheric acidity and critical load assessment, over the semi arid tract of northern India. The Critical Load approach alongwith integrated assessment models has been used in the European nations for policy formations to reduce acidic emissions. This unique approach was applied to assess the of vulnerability of natural systems to the present day atmospheric pollution scenario. The calculated values of critical loads of sulphur ( 225 - 275 eq/ha/yr) and nitrogen (298 - 303 eq/ha/yr), for the soil system in Delhi, were calculated with respect to Anjan grass, Hibiscus and Black siris. The present loads of sulphur (PL(S) = 26.40 eq/ha/yr) and nitrogen (PL(N) = 36.51 eq/ha/yr) were found to be much lower than their critical loads without posing any danger of atmospheric acidic deposition on the soil systems. The study indicated that the system is still protective due to high pH of soil. The nature of buffering capability of calcium derived from soil dust can be considered as a natural tool to combat acidification in the Indian region. The results showed that the pollution status in Delhi is still within the safe limits. However, at the pace at which the city is growing, it is likely that in coming decades, it may exceed these critical values. In order to set deposition limits and avoid adverse effects of acidic deposition this approach can be applied in India too. Such approach is very useful, not only in abating pollution but also in devising means of cost optimal emission abatement strategies.

  9. Adsorption mechanism of acids and bases in reversed-phase liquid chromatography in weak buffered mobile phases designed for liquid chromatography/mass spectrometry

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2009-01-01

    The overloaded band profiles of five acido-basic compounds were measured, using weakly buffered mobile phases. Low buffer concentrations were selected to provide a better understanding of the band profiles recorded in LC/MS analyses, which are often carried out at low buffer concentrations. In this work, 10 {micro}L samples of a 50 mM probe solution were injected into C{sub 18}-bonded columns using a series of five buffered mobile phases at {sub W}{sup S}pH between 2 and 12. The retention times and the shapes of the bands were analyzed based on thermodynamic arguments. A new adsorption model that takes into account the simultaneous adsorption of the acidic and the basic species onto the endcapped adsorbent, predicts accurately the complex experimental profiles recorded. The adsorption mechanism of acido-basic compounds onto RPLC phases seems to be consistent with the following microscopic model. No matter whether the acid or the base is the neutral or the basic species, the neutral species adsorbs onto a large number of weak adsorption sites (their saturation capacity is several tens g/L and their equilibrium constant of the order of 0.1 L/g). In contrast, the ionic species adsorbs strongly onto fewer active sites (their saturation capacity is about 1 g/L and their equilibrium constant of the order of a few L/g). From a microscopic point of view and in agreement with the adsorption isotherm of the compound measured by frontal analysis (FA) and with the results of Monte-Carlo calculations performed by Schure et al., the first type of adsorption sites are most likely located in between C{sub 18}-bonded chains and the second type of adsorption sites are located deeper in contact with the silica surface. The injected concentration (50 mM) was too low to probe the weakest adsorption sites (saturation capacity of a few hundreds g/L with an equilibrium constant of one hundredth of L/g) that are located at the very interface between the C{sub 18}-bonded layer and the bulk

  10. Isolation and characterization of Chinese standard fulvic acid sub-fractions separated from forest soil by stepwise elution with pyrophosphate buffer.

    PubMed

    Bai, Yingchen; Wu, Fengchang; Xing, Baoshan; Meng, Wei; Shi, Guolan; Ma, Yan; Giesy, John P

    2015-01-01

    XAD-8 adsorption technique coupled with stepwise elution using pyrophosphate buffers with initial pH values of 3, 5, 7, 9, and 13 was developed to isolate Chinese standard fulvic acid (FA) and then separated the FA into five sub-fractions: FApH3, FApH5, FApH7, FApH9 and FApH13, respectively. Mass percentages of FApH3-FApH13 decreased from 42% to 2.5%, and the recovery ratios ranged from 99.0% to 99.5%. Earlier eluting sub-fractions contained greater proportions of carboxylic groups with greater polarity and molecular mass, and later eluting sub-fractions had greater phenolic and aliphatic content. Protein-like components, as well as amorphous and crystalline poly(methylene)-containing components were enriched using neutral and basic buffers. Three main mechanisms likely affect stepwise elution of humic components from XAD-8 resin with pyrophosphate buffers including: 1) the carboxylic-rich sub-fractions are deprotonated at lower pH values and eluted earlier, while phenolic-rich sub-fractions are deprotonated at greater pH values and eluted later. 2) protein or protein-like components can be desorbed and eluted by use of stepwise elution as progressively greater pH values exceed their isoelectric points. 3) size exclusion affects elution of FA sub-fractions. Successful isolation of FA sub-fractions will benefit exploration of the origin, structure, evolution and the investigation of interactions with environmental contaminants. PMID:25735451

  11. Isolation and Characterization of Chinese Standard Fulvic Acid Sub-fractions Separated from Forest Soil by Stepwise Elution with Pyrophosphate Buffer

    NASA Astrophysics Data System (ADS)

    Bai, Yingchen; Wu, Fengchang; Xing, Baoshan; Meng, Wei; Shi, Guolan; Ma, Yan; Giesy, John P.

    2015-03-01

    XAD-8 adsorption technique coupled with stepwise elution using pyrophosphate buffers with initial pH values of 3, 5, 7, 9, and 13 was developed to isolate Chinese standard fulvic acid (FA) and then separated the FA into five sub-fractions: FApH3, FApH5, FApH7, FApH9 and FApH13, respectively. Mass percentages of FApH3-FApH13 decreased from 42% to 2.5%, and the recovery ratios ranged from 99.0% to 99.5%. Earlier eluting sub-fractions contained greater proportions of carboxylic groups with greater polarity and molecular mass, and later eluting sub-fractions had greater phenolic and aliphatic content. Protein-like components, as well as amorphous and crystalline poly(methylene)-containing components were enriched using neutral and basic buffers. Three main mechanisms likely affect stepwise elution of humic components from XAD-8 resin with pyrophosphate buffers including: 1) the carboxylic-rich sub-fractions are deprotonated at lower pH values and eluted earlier, while phenolic-rich sub-fractions are deprotonated at greater pH values and eluted later. 2) protein or protein-like components can be desorbed and eluted by use of stepwise elution as progressively greater pH values exceed their isoelectric points. 3) size exclusion affects elution of FA sub-fractions. Successful isolation of FA sub-fractions will benefit exploration of the origin, structure, evolution and the investigation of interactions with environmental contaminants.

  12. Isolation and Characterization of Chinese Standard Fulvic Acid Sub-fractions Separated from Forest Soil by Stepwise Elution with Pyrophosphate Buffer

    PubMed Central

    Bai, Yingchen; Wu, Fengchang; Xing, Baoshan; Meng, Wei; Shi, Guolan; Ma, Yan; Giesy, John P.

    2015-01-01

    XAD-8 adsorption technique coupled with stepwise elution using pyrophosphate buffers with initial pH values of 3, 5, 7, 9, and 13 was developed to isolate Chinese standard fulvic acid (FA) and then separated the FA into five sub-fractions: FApH3, FApH5, FApH7, FApH9 and FApH13, respectively. Mass percentages of FApH3-FApH13 decreased from 42% to 2.5%, and the recovery ratios ranged from 99.0% to 99.5%. Earlier eluting sub-fractions contained greater proportions of carboxylic groups with greater polarity and molecular mass, and later eluting sub-fractions had greater phenolic and aliphatic content. Protein-like components, as well as amorphous and crystalline poly(methylene)-containing components were enriched using neutral and basic buffers. Three main mechanisms likely affect stepwise elution of humic components from XAD-8 resin with pyrophosphate buffers including: 1) the carboxylic-rich sub-fractions are deprotonated at lower pH values and eluted earlier, while phenolic-rich sub-fractions are deprotonated at greater pH values and eluted later. 2) protein or protein-like components can be desorbed and eluted by use of stepwise elution as progressively greater pH values exceed their isoelectric points. 3) size exclusion affects elution of FA sub-fractions. Successful isolation of FA sub-fractions will benefit exploration of the origin, structure, evolution and the investigation of interactions with environmental contaminants. PMID:25735451

  13. Peak shapes of acids and bases under overloaded conditions in reversed-phase liquid chromatography, with weakly buffered mobile phases of various pH: A thermodynamic interpretation

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A

    2009-01-01

    We measured overloaded band profiles for a series of nine compounds (phenol, caffeine, 3-phenyl 1-propanol, 2-phenylbutyric acid, amphetamine, aniline, benzylamine, p-toluidine, and procainamidium chloride) on columns packed with four different C{sub 18}-bonded packing materials: XTerra-C{sub 18}, Gemini-C{sub 18}, Luna-C{sub 18}(2), and Halo-C{sub 18}, using buffered methanol-water mobile phases. The {sub W}{sup S}pH of the mobile phase was increased from 2.6 to 11.3. The buffer concentration (either phosphate, acetate, or carbonate buffers) was set constant at values below the maximum concentration of the sample in the band. The influence of the surface chemistry of the packing material on the retention and the shape of the peaks was investigated. Adsorbents having a hybrid inorganic/organic structure tend to give peaks exhibiting moderate or little tailing. The retention and the shape of the band profiles can easily be interpreted at {sub W}{sup S}pHs that are well above or well below the {sub W}{sup S}pK{sub a} of the compound studied. In contrast, the peak shapes in the intermediary pH range (i.e., close to the compound {sub W}{sup S}pK{sub a}) have rarely been studied. These shapes reveal the complexity of the competitive adsorption behavior of couples of acido-basic conjugated compounds at {sub W}{sup S}pHs that are close to their {sub W}{sup S}pK{sub a}. They also reveal the role of the buffer capacity on the resulting peak shape. With increasing {sub W}{sup S}pH, the overloaded profiles are first langmuirian (isotherm type I) at low {sub W}{sup S}pHs, they become S-shaped (isotherm type II), then anti-langmuirian (isotherm type III), S-shaped again at intermediate {sub W}{sup S}pHs, and finally return to a langmuirian shape at high {sub W}{sup S}pHs. A new general adsorption isotherm model that takes into account the dissociation equilibrium of conjugated acidic and basic species in the bulk mobile phase accounts for these transient band shapes. An

  14. Oligosaccharide-based Surfactant/Citric Acid Buffer System Stabilizes Lactate Dehydrogenase during Freeze-drying and Storage without the Addition of Natural Sugar.

    PubMed

    Ogawa, Shigesaburo; Kawai, Ryuichiro; Koga, Maito; Asakura, Kouichi; Takahashi, Isao; Osanai, Shuichi

    2016-06-01

    Experiments were conducted to assess the maintenance effects of oligosaccharide-based surfactants on the enzymatic activity of a model protein, lactate dehydrogenase (LDH), during freeze-drying and room temperature storage using the citric acid buffer system. Oligosaccharide-based surfactants, which exhibit a high glass transition temperature (Tg), promoted the eminent retention of enzymatic activity during these protocols, whereas monosaccharide-based surfactants with a low Tg displayed poor performance at high concentration, albeit much better than that of Tween 80 at middle concentration. The increase in the alkyl chain length did not exert positive effects as observed for the maintenance effect during freeze-thawing, but an amphiphilic nature and a glass forming ability were crucial for the effective stabilization at a low excipient concentration during freeze-drying. Even a low oligosaccharide-based surfactant content (0.1 mg mL(-1)) could maintain LDH activity during freeze-drying, but a high surfactant content (1.0 mg mL(-1)) was required to prevent buffer precipitation and retain high LDH activity on storage. Regarding storage, glass formation restricted molecular mobility in the lyophilized matrix, and LDH activity was effectively retained. The present results describe a strategy based on the glass-forming ability of surfactant-type excipients that affords a natural sugar-free formulation or an alternative use for polysorbate-type surfactants. PMID:27181251

  15. Understanding, Deriving, and Computing Buffer Capacity

    NASA Astrophysics Data System (ADS)

    Urbansky, Edward T.; Schock, Michael R.

    2000-12-01

    The concept of buffer capacity appears in varied disciplines, including bio-, geo-, analytical, and environmental chemistry, physiology, medicine, dentistry, and agriculture. Unfortunately, however, derivation and systematic calculation of buffer capacity is a topic that seems to be neglected in the undergraduate analytical chemistry curriculum. In this work, we give an account of the development of the buffer capacity concept and derive the buffer capacity contribution equations for buffer systems containing mono-, di-, and triprotic weak acids (and their conjugate bases) and aluminum(III), which undergoes hydrolysis. A brief review of pH is provided because pH is involved in applying buffer capacity to the real world. In addition, we discuss evaluation of the equations, numerical approximation of buffer capacity when an analytic solution is not derived, and the mathematical properties of the buffer capacity expressions.

  16. DISTRIBUTION OF LANTHANIDE AND ACTINIDE ELEMENTS BETWEEN BIS-(2-ETHYLHEXYL)PHOSPHORIC ACID AND BUFFERED LACTATE SOLUTIONS CONTAINING SELECTED COMPLEXANTS

    SciTech Connect

    Rudisill, Tracy S.; Diprete, David P.; Thompson, Major C.

    2013-04-15

    With the renewed interest in the closure of the nuclear fuel cycle, the TALSPEAK process is being considered for the separation of Am and Cm from the lanthanide fission products in a next generation reprocessing plant. However, an efficient separation requires tight control of the pH which likely will be difficult to achieve on a large scale. To address this issue, we measured the distribution of lanthanide and actinide elements between aqueous and organic phases in the presence of complexants which were potentially less sensitive to pH control than the diethylenetriaminepentaacetic (DTPA) used in the process. To perform the extractions, a rapid and accurate method was developed for measuring distribution coefficients based on the preparation of lanthanide tracers in the Savannah River National Laboratory neutron activation analysis facility. The complexants tested included aceto-, benzo-, and salicylhydroxamic acids, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and ammonium thiocyanate (NH{sub 4}SCN). The hydroxamic acids were the least effective of the complexants tested. The separation factors for TPEN and NH{sub 4}SCN were higher, especially for the heaviest lanthanides in the series; however, no conditions were identified which resulted in separations factors which consistently approached those measured for the use of DTPA.

  17. Dietary Supplementation of Benzoic Acid and Essential Oil Compounds Affects Buffering Capacity of the Feeds, Performance of Turkey Poults and Their Antioxidant Status, pH in the Digestive Tract, Intestinal Microbiota and Morphology

    PubMed Central

    Giannenas, I.; Papaneophytou, C. P.; Tsalie, E.; Pappas, I.; Triantafillou, E.; Tontis, D.; Kontopidis, G. A.

    2014-01-01

    Three trials were conducted to evaluate the effect of supplementation of a basal diet with benzoic acid or thymol or a mixture of essential oil blends (MEO) or a combination of benzoic acid with MEO (BMEO) on growth performance of turkey poults. Control groups were fed a basal diet. In trial 1, benzoic acid was supplied at levels of 300 and 1,000 mg/kg. In trial 2, thymol or the MEO were supplied at levels of 30 mg/kg. In trial 3, the combination of benzoic acid with MEO was evaluated. Benzoic acid, MEO and BMEO improved performance, increased lactic acid bacteria populations and decreased coliform bacteria in the caeca. Thymol, MEO and BMEO improved antioxidant status of turkeys. Benzoic acid and BMEO reduced the buffering capacity compared to control feed and the pH values of the caecal content. Benzoic acid and EOs may be suggested as an effective alternative to AGP in turkeys. PMID:25049947

  18. Development of myoglobin concentration and acid buffering capacity in harp (Pagophilus groenlandicus) and hooded (Cystophora cristata) seals from birth to maturity.

    PubMed

    Lestyk, Keri C; Folkow, L P; Blix, A S; Hammill, M O; Burns, J M

    2009-11-01

    Pinnipeds rely on muscle oxygen stores to help support aerobic diving, therefore muscle maturation may influence the behavioral ecology of young pinnipeds. To investigate the pattern of muscle development, myoglobin concentration ([Mb]) and acid buffering ability (beta) was measured in ten muscles from 23 harp and 40 hooded seals of various ages. Adult [Mb] ranged from 28-97 to 35-104 mg g tissue(-1) in harp and hooded seals, respectively, with values increasing from the cervical, non-swimming muscles to the main swimming muscles of the lumbar region. Neonatal and weaned pup muscles exhibited lower (approximately 30% adult values) and less variable [Mb] across the body than adults. In contrast, adult beta showed little regional variation (60-90 slykes), while high pup values (approximately 75% adult values) indicate significant in utero development. These findings suggest that intra-uterine conditions are sufficiently hypoxic to stimulate prenatal beta development, but that [Mb] development requires additional postnatal signal such as exercise, and/or growth factors. However, because of limited development in both beta and [Mb] during the nursing period, pups are weaned with muscles with lower aerobic and anaerobic capacities than those of adults. PMID:19565249

  19. Evaluation of amino acid ester-based ionic liquids as buffer additives in CE for the separation of 2-arylpropionic acids nonsteroidal anti-inflammatory drugs.

    PubMed

    Mavroudi, Maria C; Kapnissi-Christodoulou, Constantina P

    2014-09-01

    The aim of the present study is the CE performance evaluation for the separation of 2-arylpropionic acid nonsteroidal anti-inflammatory drugs. In particular, the separation of indoprofen, carprofen, ketoprofen, ibuprofen, and flurbiprofen was obtained by supporting the BGE either with SDS or an amino acid ester-based ionic liquid (AAIL). The performance of these additives was evaluated by comparing migration times, efficiencies and %RSD values. The addition of the AAIL into the BGE provided baseline separation within 10 min, while in the case of SDS, the analytes eluted within 23 min. The optimum conditions involve a BGE of 100 mM Tris/10 mM sodium tetraboratedecahydrate (pH 8) and 40 mM l-alanine tert butyl ester lactate or 10 mM SDS and a temperature of 35°C for AAIL and 20°C for SDS. The run-to-run reproducibility was evaluated by computing the %RSD values of the EOF and the analyte peaks. When the AAIL was used, an excellent reproducibility was obtained, since all %RSD values were below 1.3%. On the contrary, the addition of SDS resulted in much higher RSD values (2.1-11.7%). The efficiency values of all analyte peaks were above 102 000 for l-AlaC4 Lac, in comparison to SDS, which provided efficiency values between 47000 and 76000. Finally, in an attempt to study the synergistic effect of SDS and AAIL, both additives were added into the BGE at concentrations of 10 and 40 mM, respectively. The results were similar to the ones obtained when SDS was used as the sole additive. PMID:24853394

  20. VIRTUAL FRAME BUFFER INTERFACE

    NASA Technical Reports Server (NTRS)

    Wolfe, T. L.

    1994-01-01

    Large image processing systems use multiple frame buffers with differing architectures and vendor supplied user interfaces. This variety of architectures and interfaces creates software development, maintenance, and portability problems for application programs. The Virtual Frame Buffer Interface program makes all frame buffers appear as a generic frame buffer with a specified set of characteristics, allowing programmers to write code which will run unmodified on all supported hardware. The Virtual Frame Buffer Interface converts generic commands to actual device commands. The virtual frame buffer consists of a definition of capabilities and FORTRAN subroutines that are called by application programs. The virtual frame buffer routines may be treated as subroutines, logical functions, or integer functions by the application program. Routines are included that allocate and manage hardware resources such as frame buffers, monitors, video switches, trackballs, tablets and joysticks; access image memory planes; and perform alphanumeric font or text generation. The subroutines for the various "real" frame buffers are in separate VAX/VMS shared libraries allowing modification, correction or enhancement of the virtual interface without affecting application programs. The Virtual Frame Buffer Interface program was developed in FORTRAN 77 for a DEC VAX 11/780 or a DEC VAX 11/750 under VMS 4.X. It supports ADAGE IK3000, DEANZA IP8500, Low Resolution RAMTEK 9460, and High Resolution RAMTEK 9460 Frame Buffers. It has a central memory requirement of approximately 150K. This program was developed in 1985.

  1. The buffer capacity of airway epithelial secretions

    PubMed Central

    Kim, Dusik; Liao, Jie; Hanrahan, John W.

    2014-01-01

    The pH of airway epithelial secretions influences bacterial killing and mucus properties and is reduced by acidic pollutants, gastric reflux, and respiratory diseases such as cystic fibrosis (CF). The effect of acute acid loads depends on buffer capacity, however the buffering of airway secretions has not been well characterized. In this work we develop a method for titrating micro-scale (30 μl) volumes and use it to study fluid secreted by the human airway epithelial cell line Calu-3, a widely used model for submucosal gland serous cells. Microtitration curves revealed that HCO−3 is the major buffer. Peak buffer capacity (β) increased from 17 to 28 mM/pH during forskolin stimulation, and was reduced by >50% in fluid secreted by cystic fibrosis transmembrane conductance regulator (CFTR)-deficient Calu-3 monolayers, confirming an important role of CFTR in HCO−3 secretion. Back-titration with NaOH revealed non-volatile buffer capacity due to proteins synthesized and released by the epithelial cells. Lysozyme and mucin concentrations were too low to buffer Calu-3 fluid significantly, however model titrations of porcine gastric mucins at concentrations near the sol-gel transition suggest that mucins may contribute to the buffer capacity of ASL in vivo. We conclude that CFTR-dependent HCO−3 secretion and epithelially-derived proteins are the predominant buffers in Calu-3 secretions. PMID:24917822

  2. Common data buffer

    NASA Technical Reports Server (NTRS)

    Byrne, F.

    1981-01-01

    Time-shared interface speeds data processing in distributed computer network. Two-level high-speed scanning approach routes information to buffer, portion of which is reserved for series of "first-in, first-out" memory stacks. Buffer address structure and memory are protected from noise or failed components by error correcting code. System is applicable to any computer or processing language.

  3. Effect of temperature and solvent composition on acid dissociation equilibria, I: Sequenced (s)(s)pKa determination of compounds commonly used as buffers in high performance liquid chromatography coupled to mass spectroscopy detection.

    PubMed

    Padró, Juan M; Acquaviva, Agustín; Tascon, Marcos; Gagliardi, Leonardo G; Castells, Cecilia B

    2012-05-01

    A new automated and rapid potentiometric method for determining the effect of organic-solvent composition on pK(a) has been developed. It is based on the measurements of pH values of buffer solutions of variable solvent compositions using a combined glass electrode. Additions of small volumes of one precisely thermostated solution into another, both containing exactly the same analytical concentrations of the buffer components, can produce continuous changes in the solvent composition. Two sequences of potential measurements, one of increasing and the other of decreasing solvent content, are sufficient to obtain the pK(a) values of the acidic compound within the complete solvent-composition range in about 2h. The experimental design, procedures, and calculations needed to convert the measured pH into the thermodynamic pK(a) values are thoroughly discussed. This rapid and automated method allows the systematic study of the effect of solvent compositions and temperatures on the pK(a). It has been applied to study the dissociation constants of two monoprotic acids: formic acid and triethylamine:HCl in acetonitrile/water mixtures within the range from 0 to 90% (v/v) at temperatures between 20°C and 60°C. These volatile compounds are frequently used to control the pH of the mobile phase in HPLC, especially in methods coupled to mass-spectrometry detection. The obtained pK(a) values are in excellent agreement with those previously reported. The results were fitted to empirical functions between pK(a) and temperature and composition. These equations, which can be used to estimate the pK(a) of these substances at any composition and temperature, would be highly useful in practical work during chromatographic method development. PMID:22502616

  4. The SVT Hit Buffer

    SciTech Connect

    Belforte, S.; Dell`Orso, M.; Donati, S.

    1996-06-01

    The Hit Buffer is part of the Silicon Vertex Tracker, a trigger processor dedicated to the reconstruction of particle trajectories in the Silicon Vertex Detector and the Central Tracking Chamber of the Collider Detector at Fermilab. The Hit Buffer is a high speed data-traffic node, where thousands of words are received in arbitrary order and simultaneously organized in an internal structured data base, to be later promptly retrieved and delivered in response to specific requests. The Hit Buffer is capable of processing data at a rate of 25 MHz, thanks to the use of special fast devices like Cache-Tag RAMs and high performance Erasable Programmable Logic Devices from the XILINX XC7300 family.

  5. Online concentration by field-amplified sample injection in acidic buffer for analysis of fangchinoline and tetrandrine in herbal medicine by flow injection-micellar electrokinetic capillary chromatography.

    PubMed

    Liu, Lihong; Chen, Xingguo; Hu, Zhide

    2005-12-01

    A novel, rapid, and continuous online concentration approach based on field-amplified sample injection for the analysis of fangchinoline and tetrandrine was developed in this paper by combination of flow injection-MEKC. The BGE used was a solution composed of 75 mM H3PO4-triethylamine-2.5% v/v polyoxyethylene sorbitan monolaurate-20% v/v methanol buffer (pH* 5.0). The analytes prepared in 50% v/v aqueous ethanol were used as the test analytes. Sample was injected electrokinetically between plugs of water. When the cations reached the boundary between the water plug and BGE, they slowed down and became concentrated. Thereafter, MEKC was initiated for the separation. This results in 6.8-8.9-fold improvement in concentration sensitivity relative to conventional CE methods. The separation could be achieved within 10 min and sample throughput rate can reach up to 50/h. The repeatability (defined as RSD) was 4.8, 4.4% with peak height evaluation and 3.6, 0.94% with peak area evaluation for TET and FAN, respectively. PMID:16259014

  6. Ruminal buffers: temporal effects on buffering capacity and pH of ruminal fluid from cows fed a high concentrate diet.

    PubMed

    Le Ruyet, P; Tucker, W B

    1992-04-01

    In vitro characteristics of several buffers and alkalinizing agents commonly utilized to reduce ruminal acid load were evaluated. Ruminal fluid was collected from five cows consuming a diet containing concentrate and sorghum silage in a 68:32 ratio (DM basis). This fluid was incubated with either NaHCO3, a natural sodium sesquicarbonate, a multielement buffer or MgO (7.1 g/L of ruminal fluid), or no buffer for 48 h; flasks were removed and analyzed for pH, buffering capacity, and buffer value index every 12 h during the 48-h incubation. The buffer value index accounts simultaneously for alterations in pH and buffering capacity. Compared with the unbuffered control, all buffering compounds increased ruminal fluid buffer value index. However, the buffer value index separated these buffering compounds into two categories. The NaH-CO3 and sodium sesquicarbonate exhibited similar buffer value indexes; both were markedly higher than those for the multielement buffer and MgO. Although NaHCO3 and sodium sesquicarbonate each increased both ruminal fluid pH and buffering capacity sharply, the multielement buffer only increased pH and buffering capacity moderately. The increase in buffer value index for MgO primarily was due to an increase in pH. Both NaHCO3 and sodium sesquicarbonate were fully active within the first 12 h of incubation; activity of multielement buffer and MgO reached a plateau at 24 h. Compared with the multielement buffer and MgO, NaHCO3 and sodium sesquicarbonate should be more beneficial in preventing short-term postprandial increases in ruminal fluid hydrogen ion concentration; because of their slower release rates, the multielement buffer and MgO should help stabilize ruminal acid-base status, but efficacy might be reduced because of passage out of the rumen. PMID:1315810

  7. Improved pH buffering agent for sodium hypochlorite

    NASA Technical Reports Server (NTRS)

    Nash, J. R.; Veeder, L. N.

    1969-01-01

    Sodium citrate/citric acid was found to be an effective buffer for pH control when used with sodium hypochlorite. The mixture does not corrode aluminum. The buffer appears to form a type of conversion coating that may provide corrosion-resistant properties to aluminum in other applications.

  8. Visualization of Buffer Capacity with 3-D "Topo" Surfaces: Buffer Ridges, Equivalence Point Canyons and Dilution Ramps

    ERIC Educational Resources Information Center

    Smith, Garon C.; Hossain, Md Mainul

    2016-01-01

    BufCap TOPOS is free software that generates 3-D topographical surfaces ("topos") for acid-base equilibrium studies. It portrays pH and buffer capacity behavior during titration and dilution procedures. Topo surfaces are created by plotting computed pH and buffer capacity values above a composition grid with volume of NaOH as the x axis…

  9. [Uptake of fluoride into enamel and its effect on acid resistance by application of fluoride-releasing sealant--Part 2. Effect of application time and immersion time into buffer after its removal].

    PubMed

    Kato, K

    1991-03-01

    The purpose of this study was to investigate the relationship between the amount of fluoride in the enamel, taken from a fluoride-releasing sealant (F + sealant) and acid resistance. The F + sealant was applied to the bovine enamel from 1 week to 6 months. After the removal of the F + sealant, the bovine teeth were immersed in phosphate buffer from 1 month to 6 months. At each time period, the enamel was biopsied with acid and its fluoride and calcium concentration were analyzed. Results were as follows: (1) It was suitable to immerse the teeth in 1M KOH solution for 2 days in order to remove the loosely bound fluoride produced by the fluoride application from the enamel. (2) The amount of fluoride in the surface enamel increased in proportion to the application time of F + sealant. (3) The amount of calcium dissolved from the enamel showed the significant decrease by the F + sealant application, while no difference was shown by the application time. (4) The amount of fluoride in the surface enamel acquired by the F + sealant was maintained for 6 months after the removal of the F + sealant. (5) The amount of calcium dissolved from the enamel showed no difference in the period of immersion time. PMID:2066630

  10. Valuation of forested buffers

    NASA Astrophysics Data System (ADS)

    Basnyat, Prakash

    The research concentrated on two fronts: (1) defining relationships between land use complex and nitrate and sediment concentrations; and (2) developing a method for assessing the extent of potential and water quality improvements available through land management options and their associated costs. In this work, selected basins of the Fish River (Alabama) were delineated, land use/land cover types were classified, and "contributing zones" were delineated using Geographic Information System (GIS) and Remote Sensing (RS) analytical tools. Water samples collected from these basins were analyzed for their nutrient contents. Based on measured nitrate and sediment concentrations in basin streams, a linkage model was developed. This linkage model relates land use/land cover with the pollution levels in the stream. The linkage model was evaluated at three different scales: (1) the basin scale; (2) the contributing zone scale; and (3) the stream buffer/riparian zone scale. The contributing zone linkage model suggests that forests act as a sink or transformation zone. Residential/urban/built-up areas were identified as the strongest contributors of nitrate in the contributing zones model and active agriculture was identified as the second largest contributor. Regression results for the "land use/land cover diversity" model (stream buffer/riparian zone scale) suggest that areas that are close (adjacent) to the stream and any disturbances in these areas will have major impacts on stream water quality. The economic model suggests the value of retiring lands from agricultural land uses to forested buffers varies from 0 to 3067 per hectare, depending on the types of crops currently grown. Along with conversion costs, this land value forms the basis for estimates of the costs of land management options for improving (or maintaining) water quality throughout the study area. The model also shows the importance of stream-side management zones, which are key to maintenance of stream

  11. Complexation of buffer constituents with neutral complexation agents: part I. Impact on common buffer properties.

    PubMed

    Riesová, Martina; Svobodová, Jana; Tošner, Zdeněk; Beneš, Martin; Tesařová, Eva; Gaš, Bohuslav

    2013-09-17

    The complexation of buffer constituents with the complexation agent present in the solution can very significantly influence the buffer properties, such as pH, ionic strength, or conductivity. These parameters are often crucial for selection of the separation conditions in capillary electrophoresis or high-pressure liquid chromatography (HPLC) and can significantly affect results of separation, particularly for capillary electrophoresis as shown in Part II of this paper series (Beneš, M.; Riesová, M.; Svobodová, J.; Tesařová, E.; Dubský, P.; Gaš, B. Anal. Chem. 2013, DOI: 10.1021/ac401381d). In this paper, the impact of complexation of buffer constituents with a neutral complexation agent is demonstrated theoretically as well as experimentally for the model buffer system composed of benzoic acid/LiOH or common buffers (e.g., CHES/LiOH, TAPS/LiOH, Tricine/LiOH, MOPS/LiOH, MES/LiOH, and acetic acid/LiOH). Cyclodextrins as common chiral selectors were used as model complexation agents. We were not only able to demonstrate substantial changes of pH but also to predict the general complexation characteristics of selected compounds. Because of the zwitterion character of the common buffer constituents, their charged forms complex stronger with cyclodextrins than the neutral ones do. This was fully proven by NMR measurements. Additionally complexation constants of both forms of selected compounds were determined by NMR and affinity capillary electrophoresis with a very good agreement of obtained values. These data were advantageously used for the theoretical descriptions of variations in pH, depending on the composition and concentration of the buffer. Theoretical predictions were shown to be a useful tool for deriving some general rules and laws for complexing systems. PMID:23889602

  12. Buffer Capacity: An Undergraduate Laboratory Experiment.

    ERIC Educational Resources Information Center

    Russo, Steven O.; Hanania, George I. H.

    1987-01-01

    Describes a quantitative experiment designed to demonstrate buffer action and the measurement of buffer capacity. Discusses how to make acetate buffers, determine their buffer capacity, plot the capacity/pH curve, and interpret the data obtained. (TW)

  13. Virtual Frame Buffer Interface Program

    NASA Technical Reports Server (NTRS)

    Wolfe, Thomas L.

    1990-01-01

    Virtual Frame Buffer Interface program makes all frame buffers appear as generic frame buffer with specified set of characteristics, allowing programmers to write codes that run unmodified on all supported hardware. Converts generic commands to actual device commands. Consists of definition of capabilities and FORTRAN subroutines called by application programs. Developed in FORTRAN 77 for DEC VAX 11/780 or DEC VAX 11/750 computer under VMS 4.X.

  14. The buffer effect in neutral electrolyte supercapacitors

    NASA Astrophysics Data System (ADS)

    Vindt, Steffen T.; Skou, Eivind M.

    2016-02-01

    The observation that double-layer capacitors based on neutral aqueous electrolytes can have significantly wider usable potential windows than those based on acidic or alkaline electrolytes is studied. This effect is explained by a local pH change taking place at the electrode surfaces, leading to a change in the redox potential of water in opposite directions on the two electrodes, resulting in the wider stability window. The magnitude of this effect is suggested to be dependent on the buffer capacity, rather than the intrinsic pH value of the electrolyte. This is confirmed by studying the impact of addition of a buffer to such systems. It is shown that a 56 % higher dynamic storage capacity may be achieved, simply by controlling the buffer capacity of the electrolyte. The model system used, is based on a well-known commercial activated carbon (NORIT™ A SUPRA) as the electrode material, aqueous potassium nitrate as the electrolyte and potassium phosphates as the buffer system.

  15. A buffer value index to evaluate effects of buffers on ruminal milieu in cows fed high or low concentrate, silage, or hay diets.

    PubMed

    Tucker, W B; Hogue, J F; Aslam, M; Lema, M; Martin, M; Owens, F N; Shin, I S; Le Ruyet, P; Adams, G D

    1992-03-01

    Our objective was to develop a buffer value index that would incorporate alterations in both ruminal fluid pH and buffering capacity as indicators of the influence of dietary buffering and alkalinizing agents on ruminal acid-base status. This index was evaluated using ruminal fluid from four lactating Holstein cows fed either sorghum silage or alfalfa hay in high or low concentrate diets. Ruminal fluid was incubated in vitro for 1, 2, 3, 4, or 5 h with no buffer or with 7.1 g of either NaHCO3, sodium sesquicarbonate, or a multielement buffer added per liter of ruminal fluid. Ruminal fluid pH was lower for diets based on high concentrate or alfalfa; buffering capacity between pH 5 and 7 was greater for high concentrate diets but was not affected by forage type. Ruminal fluid pH was higher for sesquicarbonate than for NaHCO3, the multielement buffer, or the control; however, ruminal fluid H+ concentration was similar between sesquicarbonate and NaHCO3, and both were lower than for the multielement buffer. Hydrogen ion concentration for the multielement buffer was lower than for the control. Buffering capacity was highest for NaHCO3, followed by sesquicarbonate, the multielement buffer, and the control. The buffer value index, which accounted for alterations in both H+ concentration and buffering capacity, was highest for NaCHO3, followed by sesquicarbonate, the multielement buffer, and the control. The poor response to the multielement buffer may be attributable to our relatively short incubation interval (less than 5 h). Dietary buffers increase both ruminal fluid pH and buffering capacity; both of these responses are beneficial.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1314858

  16. Ring Buffered Network Bus

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This report describes the research effort to demonstrate the integration of a data sharing technology, Ring Buffered Network Bus, in development by Dryden Flight Research Center, with an engine simulation application, the Java Gas Turbine Simulator, in development at the University of Toledo under a grant from the Glenn Research Center. The objective of this task was to examine the application of the RBNB technologies as a key component in the data sharing, health monitoring and system wide modeling elements of the NASA Aviation Safety Program (AVSP) [Golding, 1997]. System-wide monitoring and modeling of aircraft and air safety systems will require access to all data sources which are relative factors when monitoring or modeling the national airspace such as radar, weather, aircraft performance, engine performance, schedule and planning, airport configuration, flight operations, etc. The data sharing portion of the overall AVSP program is responsible for providing the hardware and software architecture to access and distribute data, including real-time flight operations data, among all of the AVSP elements. The integration of an engine code capable of numerically "flying" through recorded flight paths and weather data using a software tool that allows for distributed access of data to this engine code demonstrates initial steps toward building a system capable of monitoring and modeling the National Airspace.

  17. Oracle Log Buffer Queueing

    SciTech Connect

    Rivenes, A S

    2004-12-08

    The purpose of this document is to investigate Oracle database log buffer queuing and its affect on the ability to load data using a specialized data loading system. Experiments were carried out on a Linux system using an Oracle 9.2 database. Previous experiments on a Sun 4800 running Solaris had shown that 100,000 entities per minute was an achievable rate. The question was then asked, can we do this on Linux, and where are the bottlenecks? A secondary question was also lurking, how can the loading be further scaled to handle even higher throughput requirements? Testing was conducted using a Dell PowerEdge 6650 server with four CPUs and a Dell PowerVault 220s RAID array with 14 36GB drives and 128 MB of cache. Oracle Enterprise Edition 9.2.0.4 was used for the database and Red Hat Linux Advanced Server 2.1 was used for the operating system. This document will detail the maximum observed throughputs using the same test suite that was used for the Sun tests. A detailed description of the testing performed along with an analysis of bottlenecks encountered will be made. Issues related to Oracle and Linux will also be detailed and some recommendations based on the findings.

  18. BUFFERS AND VEGETATIVE FILTER STRIPS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Buffers and filter strips are areas of permanent vegetation located within and between agricultural fields and the water courses to which they drain. These buffers are intended to intercept and slow runoff thereby providing water quality benefits. In addition, in many settings they are intended to...

  19. The effect of oral sodium acetate administration on plasma acetate concentration and acid-base state in horses

    PubMed Central

    Waller, Amanda; Lindinger, Michael I

    2007-01-01

    Aim Sodium acetate (NaAcetate) has received some attention as an alkalinizing agent and possible alternative energy source for the horse, however the effects of oral administration remain largely unknown. The present study used the physicochemical approach to characterize the changes in acid-base status occurring after oral NaAcetate/acetic acid (NAA) administration in horses. Methods Jugular venous blood was sampled from 9 exercise-conditioned horses on 2 separate occasions, at rest and for 24 h following a competition exercise test (CET) designed to simulate the speed and endurance test of 3-day event. Immediately after the CETs horses were allowed water ad libitum and either: 1) 8 L of a hypertonic NaAcetate/acetic acid solution via nasogastric tube followed by a typical hay/grain meal (NAA trial); or 2) a hay/grain meal alone (Control trial). Results Oral NAA resulted in a profound plasma alkalosis marked by decreased plasma [H+] and increased plasma [TCO2] and [HCO3-] compared to Control. The primary contributor to the plasma alkalosis was an increased [SID], as a result of increased plasma [Na+] and decreased plasma [Cl-]. An increased [Atot], due to increased [PP] and a sustained increase in plasma [acetate], contributed a minor acidifying effect. Conclusion It is concluded that oral NaAcetate could be used as both an alkalinizing agent and an alternative energy source in the horse. PMID:18096070

  20. Buffered chlorogallate(III) ionic liquids and electrodeposition of gallium films.

    PubMed

    Seddon, Kenneth R; Srinivasan, Geetha; Swadźba-Kwaśny, Małgorzata; Wilson, Anthony R

    2013-04-01

    Buffering of Lewis acidic chlorometallate ionic liquids is a useful tool to modify their properties for electrochemical and catalytic applications. Lewis acidic chlorogallate(iii) ionic liquids containing the 1-octyl-3-methylimidazolium cation, buffered with sodium chloride, were studied using (71)Ga NMR spectroscopy and cyclic voltammetry. All the studied Lewis acidic compositions (0.50 < χGaCl3 ≤ 0.75) could be buffered to mild or moderate acidity, but not to neutrality. Electrodeposition of gallium from such buffered systems was possible, yielding deposits of improved morphology over the unbuffered ionic liquids, due to the constant melt composition maintained by the buffer. These findings were in a stark contrast with older studies on chloroaluminate(iii) ionic liquids buffered with sodium chloride. PMID:23420108

  1. Electrodialysis operation with buffer solution

    DOEpatents

    Hryn, John N.; Daniels, Edward J.; Krumdick, Greg K.

    2009-12-15

    A new method for improving the efficiency of electrodialysis (ED) cells and stacks, in particular those used in chemical synthesis. The process entails adding a buffer solution to the stack for subsequent depletion in the stack during electrolysis. The buffer solution is regenerated continuously after depletion. This buffer process serves to control the hydrogen ion or hydroxide ion concentration so as to protect the active sites of electrodialysis membranes. The process enables electrodialysis processing options for products that are sensitive to pH changes.

  2. Influence of different buffers (HEPES/MOPS) on keratinocyte cell viability and microbial growth.

    PubMed

    Dias, Kássia de Carvalho; Barbugli, Paula Aboud; Vergani, Carlos Eduardo

    2016-06-01

    This study assessed the effect of the buffers 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 3-(N-morpholino) propanesulfonic acid (MOPS) on keratinocyte cell viability and microbial growth. It was observed that RPMI buffered with HEPES, supplemented with l-glutamine and sodium bicarbonate, can be used as a more suitable medium to promote co-culture. PMID:27060444

  3. INFLUENCE OF BORATE BUFFERS ON THE ELECTROPHORETIC BEHAVIOR OF HUMIC SUBSTANCES IN CAPILLARY ZONE ELECTROPHORESIS

    EPA Science Inventory

    The influence of tetrahydroxyborate ions on the electrophoretic mobility of humic acids was evaluated by capillary electrophoresis (CE). Depending on the molarity of borate ions in the separation buffer, the humic acids exhibit electropherograms with sharp peaks consistently exte...

  4. Buffer Gas Acquisition and Storage

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F.; Lueck, Dale E.; Jennings, Paul A.; Callahan, Richard A.; Delgado, H. (Technical Monitor)

    2001-01-01

    The acquisition and storage of buffer gases (primarily argon and nitrogen) from the Mars atmosphere provides a valuable resource for blanketing and pressurizing fuel tanks and as a buffer gas for breathing air for manned missions. During the acquisition of carbon dioxide (CO2), whether by sorption bed or cryo-freezer, the accompanying buffer gases build up in the carbon dioxide acquisition system, reduce the flow of CO2 to the bed, and lower system efficiency. It is this build up of buffer gases that provide a convenient source, which must be removed, for efficient capture Of CO2 Removal of this buffer gas barrier greatly improves the charging rate of the CO2 acquisition bed and, thereby, maintains the fuel production rates required for a successful mission. Consequently, the acquisition, purification, and storage of these buffer gases are important goals of ISRU plans. Purity of the buffer gases is a concern e.g., if the CO, freezer operates at 140 K, the composition of the inert gas would be approximately 21 percent CO2, 50 percent nitrogen, and 29 percent argon. Although there are several approaches that could be used, this effort focused on a hollow-fiber membrane (HFM) separation method. This study measured the permeation rates of CO2, nitrogen (ND, and argon (Ar) through a multiple-membrane system and the individual membranes from room temperature to 193K and 10 kpa to 300 kPa. Concentrations were measured with a gas chromatograph that used a thermoconductivity (TCD) detector with helium (He) as the carrier gas. The general trend as the temperature was lowered was for the membranes to become more selective, In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar.

  5. Free flow cell electrophoresis using zwitterionic buffer

    NASA Technical Reports Server (NTRS)

    Rodkey, R. Scott

    1990-01-01

    Studies of a zwitterionic buffer formulated for cell electrophoresis were done using the McDonnell-Douglas Continuous Flow Electrophoresis System. Standard buffers were analyzed for their stability in the electrical field and the results showed that both buffers tested were inherently unstable. Further, titration studies showed that the standards buffers buffered poorly at the pH employed for electrophoresis. The zwitterionic buffer buffered well at its nominal pH and was shown to be stable in the electrical field. Comparative studies of the buffer with standard cell separation buffers using formalin fixed rabbit and goose red blood cells showed that the zwitterionic buffer gave better resolution of the fixed cells. Studies with viable hybridoma cells showed that buffer Q supported cell viability equal to Hank's Balanced Salt Solution and that hybridoma cells in different stages of the growth cycle demonstrated reproducible differences in electrophoretic mobility.

  6. A Novel Tool to Facilitate the Learning of Buffering Mechanism by Undergraduate Students of the Biological Area

    ERIC Educational Resources Information Center

    Carvalho, Eduardo O.; Nantes, Iseli L.

    2008-01-01

    In this study, the application and evaluation of a novel didactic tool (buffer kit) is described to make it easy for students in the biological area to overcome their conceptual deficiencies that render the learning of the buffering mechanism difficult. The buffer kit was constructed with double-face EVA cards with a conjugated acid formula…

  7. Buffering in cyclic gene networks

    NASA Astrophysics Data System (ADS)

    Glyzin, S. D.; Kolesov, A. Yu.; Rozov, N. Kh.

    2016-06-01

    We consider cyclic chains of unidirectionally coupled delay differential-difference equations that are mathematical models of artificial oscillating gene networks. We establish that the buffering phenomenon is realized in these system for an appropriate choice of the parameters: any given finite number of stable periodic motions of a special type, the so-called traveling waves, coexist.

  8. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    SciTech Connect

    Aines, Roger D

    2015-03-31

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  9. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    DOEpatents

    Aines, Roger D.

    2013-03-12

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  10. Cell buffer with built-in test

    NASA Technical Reports Server (NTRS)

    Ott, William E. (Inventor)

    2004-01-01

    A cell buffer with built-in testing mechanism is provided. The cell buffer provides the ability to measure voltage provided by a power cell. The testing mechanism provides the ability to test whether the cell buffer is functioning properly and thus providing an accurate voltage measurement. The testing mechanism includes a test signal-provider to provide a test signal to the cell buffer. During normal operation, the test signal is disabled and the cell buffer operates normally. During testing, the test signal is enabled and changes the output of the cell buffer in a defined way. The change in the cell buffer output can then be monitored to determine if the cell buffer is functioning correctly. Specifically, if the voltage output of the cell buffer changes in a way that corresponds to the provided test signal, then the functioning of the cell buffer is confirmed. If the voltage output of the cell buffer does not change correctly, then the cell buffer is known not to be operating correctly. Thus, the built in testing mechanism provides the ability to quickly and accurately determine if the cell buffer is operating correctly. Furthermore, the testing mechanism provides this functionality without requiring excessive device size and complexity.

  11. Laser velocimeter (autocovariance) buffer interface

    NASA Technical Reports Server (NTRS)

    Clemmons, J. I., Jr.

    1981-01-01

    A laser velocimeter (autocovariance) buffer interface (LVABI) was developed to serve as the interface between three laser velocimeter high speed burst counters and a minicomputer. A functional description is presented of the instrument and its unique features which allow the studies of flow velocity vector analysis, turbulence power spectra, and conditional sampling of other phenomena. Typical applications of the laser velocimeter using the LVABI are presented to illustrate its various capabilities.

  12. Mapping Soil pH Buffering Capacity of Selected Fields

    NASA Technical Reports Server (NTRS)

    Weaver, A. R.; Kissel, D. E.; Chen, F.; West, L. T.; Adkins, W.; Rickman, D.; Luvall, J. C.

    2003-01-01

    Soil pH buffering capacity, since it varies spatially within crop production fields, may be used to define sampling zones to assess lime requirement, or for modeling changes in soil pH when acid forming fertilizers or manures are added to a field. Our objective was to develop a procedure to map this soil property. One hundred thirty six soil samples (0 to 15 cm depth) from three Georgia Coastal Plain fields were titrated with calcium hydroxide to characterize differences in pH buffering capacity of the soils. Since the relationship between soil pH and added calcium hydroxide was approximately linear for all samples up to pH 6.5, the slope values of these linear relationships for all soils were regressed on the organic C and clay contents of the 136 soil samples using multiple linear regression. The equation that fit the data best was b (slope of pH vs. lime added) = 0.00029 - 0.00003 * % clay + 0.00135 * % O/C, r(exp 2) = 0.68. This equation was applied within geographic information system (GIS) software to create maps of soil pH buffering capacity for the three fields. When the mapped values of the pH buffering capacity were compared with measured values for a total of 18 locations in the three fields, there was good general agreement. A regression of directly measured pH buffering capacities on mapped pH buffering capacities at the field locations for these samples gave an r(exp 2) of 0.88 with a slope of 1.04 for a group of soils that varied approximately tenfold in their pH buffering capacities.

  13. Doped LZO buffer layers for laminated conductors

    DOEpatents

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2010-03-23

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  14. RESEARCH NEEDS IN RIPARIAN BUFFER RESTORATION

    EPA Science Inventory

    Riparian buffer restorations are used as management tools to produce favorable water quality impacts; moreover, the basis for riparian buffers as an instrument of water quality restoration rests on a relatively firm foundation. However, the extent to which buffers can restore rip...

  15. Buffering agents modify the hydration landscape at charged interfaces.

    PubMed

    Trewby, William; Livesey, Duncan; Voïtchovsky, Kislon

    2016-02-23

    Buffering agents are widely used to stabilise the pH of solutions in soft matter and biological sciences. They are typically composed of weak acids and bases mixed in an aqueous solution, and can interact electrostatically with charged surfaces such as biomembranes. Buffers can induce protein aggregation and structural modification of soft interfaces, but a molecular-level picture is still lacking. Here we use high-resolution atomic force microscopy to investigate the effect of five commonly used buffers, namely 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), 2-(N-morpholino)ethanesulfonic acid (MES), monosodium phosphate, saline sodium citrate (SSC) and tris(hydroxymethyl)aminomethane (Tris) on the hydration landscape of Muscovite mica in solution. Mica is an ideal model substrate due to its negative surface charge and identical lattice parameter when compared with gel-phase lipid bilayers. We show that buffer molecules can produce cohesive aggregates spanning over tens of nanometres of the interface. SSC, Tris and monosodium phosphate tend to create an amorphous mesh layer several molecules thick and with no preferential ordering. In contrast, MES and HEPES adopt epitaxial arrangements commensurate with the underlying mica lattice, suggesting that they offer the most suitable solution for high-resolution studies. To confirm that this effect persisted in biologically-relevant interfaces, the experiments were repeated on a silica-supported lipid bilayer. Similar trends were observed for this system using atomic force microscopy as well as ellipsometry. The effect of the buffering agents can be mitigated by the inclusion of salt which helps displace them from the interface. PMID:26837938

  16. Reduction of metastasis using a non-volatile buffer.

    PubMed

    Ibrahim Hashim, Arig; Cornnell, Heather H; Coelho Ribeiro, Maria de Lourdes; Abrahams, Dominique; Cunningham, Jessica; Lloyd, Mark; Martinez, Gary V; Gatenby, Robert A; Gillies, Robert J

    2011-12-01

    The tumor microenvironment is acidic as a consequence of upregulated glycolysis and poor perfusion and this acidity, in turn, promotes invasion and metastasis. We have recently demonstrated that chronic consumption of sodium bicarbonate increased tumor pH and reduced spontaneous and experimental metastases. This occurred without affecting systemic pH, which was compensated. Additionally, these prior data did not rule out the possibility that bicarbonate was working though effects on carbonic anhydrase, and not as a buffer per se. Here, we present evidence that chronic ingestion of a non-volatile buffer, 2-imidazole-1-yl-3-ethoxycarbonylpropionic acid (IEPA) with a pK (a) of 6.9 also reduced metastasis in an experimental PC3M prostate cancer mouse model. Animals (n = 30) were injected with luciferase expressing PC3M prostate cancer cells either subcutaneously (s.c., n = 10) or intravenously (i.v., n = 20). Four days prior to inoculations, half of the animals for each experiment were provided drinking water containing 200 mM IEPA buffer. Animals were imaged weekly to follow metastasis, and these data showed that animals treated with IEPA had significantly fewer experimental lung metastasis compared to control groups (P < 0.04). Consistent with prior work, the pH of treated tumors was elevated compared to controls. IEPA is observable by in vivo magnetic resonance spectroscopy and this was used to measure the presence of IEPA in the bladder, confirming that it was orally available. The results of this study indicate that metastasis can be reduced by non-volatile buffers as well as bicarbonate and thus the effect appears to be due to pH buffering per se. PMID:21861189

  17. 21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Buffered penicillin powder, penicillin powder with buffered aqueous diluent. 520.1696a Section 520.1696a Food and Drugs FOOD AND DRUG ADMINISTRATION... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered...

  18. 21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Buffered penicillin powder, penicillin powder with buffered aqueous diluent. 520.1696a Section 520.1696a Food and Drugs FOOD AND DRUG ADMINISTRATION... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered...

  19. Effect of buffers on testing of Candida species susceptibility to flucytosine.

    PubMed Central

    MacKerrow, S D; Merry, J M; Hoeprich, P D

    1987-01-01

    Synthetic amino acid medium for fungi (SAAMF) is a totally defined, nutritionally adequate, macromolecule-free culture medium for fungi that is buffered with an organic weak acid-weak base pair: 2-(N-morpholino)-propanesulfonic acid (MOPS) and 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris). In 1984, it was reported that MOPS-Tris in SAAMF antagonized the activity of flucytosine against Candida albicans (D. L. Calhoun and J. N. Galgiani, Antimicrob. Agents Chemother. 26:364-367, 1984). Accordingly, we evaluated the buffering capacity of seven synthetic organic buffers and monobasic potassium phosphate, both singly and in pairs, over the pH range 7.4 to 6.0. Of these buffers, MOPS, BES [N,N-bis(2-hydroxyethyl)-2-aminomethanesulfonic acid], a BES-MOPS combination, and KH2PO4 provided the best buffering. Growth of C. albicans, in unbuffered SAAMF was equivalent overall to that in SAAMF containing buffers, singly or in pairs. Twelve strains of C. albicans and five strains of Candida lusitaniae were tested for susceptibility to flucytosine in SAAMF, with and without buffers. In the presence of Tris, the geometric mean MICs were 6.5- and 3.6-fold higher, respectively, for C. albicans and C. lusitaniae. We recommend replacing Tris with the nonantagonistic MOPS. PMID:3294891

  20. Improving Water Quality With Conservation Buffers

    NASA Astrophysics Data System (ADS)

    Lowrance, R.; Dabney, S.; Schultz, R.

    2003-12-01

    Conservation buffer technologies are new approaches that need wider application. In-field buffer practices work best when used in combination with other buffer types and other conservation practices. Vegetative barriers may be used in combination with edge-of-field buffers to protect and improve their function and longevity by dispersing runoff and encouraging sediment deposition upslope of the buffer. It's important to understand how buffers can be managed to help reduce nutrient transport potential for high loading of nutrients from manure land application sites, A restored riparian wetland buffer retained or removed at least 59 percent of the nitrogen and 66 percent of the phosphorus that entered from an adjacent manure land application site. The Bear Creek National Restoration Demonstration Watershed project in Iowa has been the site of riparian forest buffers and filter strips creation; constructed wetlands to capture tile flow; stream-bank bioengineering; in-stream structures; and controlling livestock grazing. We need field studies that test various widths of buffers of different plant community compositions for their efficacy in trapping surface runoff, reducing nonpoint source pollutants in subsurface waters, and enhancing the aquatic ecosystem. Research is needed to evaluate the impact of different riparian grazing strategies on channel morphology, water quality, and the fate of livestock-associated pathogens and antibiotics. Integrating riparian buffers and other conservation buffers into these models is a key objective in future model development.

  1. Buffered Electrochemical Polishing of Niobium

    SciTech Connect

    Gianluigi Ciovati; Tian, Hui; Corcoran, Sean

    2011-03-01

    The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.

  2. Zinc(II) complexation by some biologically relevant pH buffers.

    PubMed

    Wyrzykowski, D; Tesmar, A; Jacewicz, D; Pranczk, J; Chmurzyński, L

    2014-12-01

    The isothermal titration calorimetry (ITC) technique supported by potentiometric titration data was used to study the interaction of zinc ions with pH buffer substances, namely 2-(N-morpholino)ethanesulfonic acid (Mes), piperazine-N,N'-bis(2-ethanesulfonic acid) (Pipes), and dimethylarsenic acid (Caco). The displacement ITC titration method with nitrilotriacetic acid as a strong, competitive ligand was applied to determine conditional-independent thermodynamic parameters for the binding of Zn(II) to Mes, Pipes, and Caco. Furthermore, the relationship between the proposed coordination mode of the buffers and the binding enthalpy has been discussed. PMID:25319620

  3. Melatonin: Buffering the Immune System

    PubMed Central

    Carrillo-Vico, Antonio; Lardone, Patricia J.; Álvarez-Sánchez, Nuria; Rodríguez-Rodríguez, Ana; Guerrero, Juan M.

    2013-01-01

    Melatonin modulates a wide range of physiological functions with pleiotropic effects on the immune system. Despite the large number of reports implicating melatonin as an immunomodulatory compound, it still remains unclear how melatonin regulates immunity. While some authors argue that melatonin is an immunostimulant, many studies have also described anti-inflammatory properties. The data reviewed in this paper support the idea of melatonin as an immune buffer, acting as a stimulant under basal or immunosuppressive conditions or as an anti-inflammatory compound in the presence of exacerbated immune responses, such as acute inflammation. The clinical relevance of the multiple functions of melatonin under different immune conditions, such as infection, autoimmunity, vaccination and immunosenescence, is also reviewed. PMID:23609496

  4. Evaluation of amine inhibitors for suitability as crevice buffering agents. Final report

    SciTech Connect

    Jayaweera, P.; Hettiarachchi, S.

    1994-03-01

    This report describes the results of a research effort to evaluate the suitability of some selected amines and amino acids as a crevice-buffering agents in pressurized water reactor (PWR) steam generators. The amines may be useful for buffering acid crevices, and the amino acids, because they contain both acidic and basic groups, may be useful for acidic and caustic crevices. Five commercially available amines and two amino acids were studied during this research. The study involved (1) the hydrolysis of these commercially available amines and amino acids, including measurement of their kinetics of decomposition, in simulated steam generator bulk water at 290 C, and (2) determination of their thermal stability in a simulated crevice environment. The study showed that, although the high-molecular-weight amines undergo hydrothermal decomposition, they have a better buffering capacity than their low-molecular-weight counterparts at 290 C. The amines provide effective crevice buffering by increasing the pH of the crevice solution by as much as 2.84 and to 4.24 units in the experimental setup used in this program. It was concluded that polyamines provide excellent buffering of the simulated crevice environment at 290 C and morpholine remains the best low-molecular-weight amine investigated. However, detailed volatility studies of the amines were not considered in this work. Such data would be needed before in-plant testing to ensure that the amines can concentrate in steam generator crevices to the levels assumed in this study.

  5. Buffer strips in composites at elevated temperature

    NASA Technical Reports Server (NTRS)

    Bigelow, C. A.

    1983-01-01

    The composite material 'buffer strip' concept is presently investigated at elevated temperatures for the case of graphite/polyimide buffer strip panels using a (45/0/45/90)2S layup, where the buffer strip material was 0-deg S-glass/polyimide. Each panel was loaded in tension until it failed, and radiographs and crack opening displacements were recorded during the tests to determine fracture onset, fracture arrest, and the extent of damage in the buffer strip after crack arrest. At 177 + or - 3 C, the buffer strips increased the panel strength by at least 40 percent in comparison with panels without buffer strips. Compared to similar panels tested at room temperature, those tested at elevated temperature had lower residual strengths, but higher failure strains.

  6. Signature-based store checking buffer

    DOEpatents

    Sridharan, Vilas; Gurumurthi, Sudhanva

    2015-06-02

    A system and method for optimizing redundant output verification, are provided. A hardware-based store fingerprint buffer receives multiple instances of output from multiple instances of computation. The store fingerprint buffer generates a signature from the content included in the multiple instances of output. When a barrier is reached, the store fingerprint buffer uses the signature to verify the content is error-free.

  7. SODR Memory Control Buffer Control ASIC

    NASA Technical Reports Server (NTRS)

    Hodson, Robert F.

    1994-01-01

    The Spacecraft Optical Disk Recorder (SODR) is a state of the art mass storage system for future NASA missions requiring high transmission rates and a large capacity storage system. This report covers the design and development of an SODR memory buffer control applications specific integrated circuit (ASIC). The memory buffer control ASIC has two primary functions: (1) buffering data to prevent loss of data during disk access times, (2) converting data formats from a high performance parallel interface format to a small computer systems interface format. Ten 144 p in, 50 MHz CMOS ASIC's were designed, fabricated and tested to implement the memory buffer control function.

  8. Study to optimize gellant polymer-water systems for the control of hypergolic spills and fires

    NASA Technical Reports Server (NTRS)

    Jennings, R. R.; Macwilliams, D. C.; Foshee, W. C.; Katzer, M. F.

    1973-01-01

    A system of buffered gelled water was developed to prevent and control fires from small spills of nitrogen tetroxide-(N2O4)-Aerozine 50-hypergolic fuel. Laboratory studies on various alkalis, buffers, and seavengers for the fuel components are described. Chilling and sodium acetate-acetic acid buffer was found to be the best additives to the gelled water. Field tests and a delivery system (airborne) for the extinguishant are described. A short movie showing the field testing is available upon request.

  9. Supported bilayer electrophoresis under controlled buffer conditions.

    PubMed

    Monson, Christopher F; Pace, Hudson P; Liu, Chunming; Cremer, Paul S

    2011-03-15

    A pH controlled flow cell device was constructed to allow electrophoretic movement of charged lipids and membrane associated proteins in supported phospholipid bilayers. The device isolated electrolysis products near the electrodes from the electrophoresis process within the bilayer. This allowed the pH over the bilayer region to remain within ±0.2 pH units or better over many hours at salt concentrations up to 10 mM. Using this setup, it was found that the electrophoretic mobility of a dye conjugated lipid (Texas Red 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (TR-DHPE)) was essentially constant between pH 3.3 and 9.3. In contrast, streptavidin, which was bound to biotinylated lipids, shifted from migrating cathodically at acidic pH values to migrating anodically under basic conditions. This shift was due to the modulation of the net charge on the protein, which changed the electrophoretic forces experienced by the macromolecule. The addition of a polyethylene glycol (PEG) cushion beneath the bilayer or the increase in the ionic strength of the buffer solution resulted in a decrease of the electroosmotic force experienced by the streptavidin with little effect on the Texas Red-DHPE. As such, it was possible in part to control the electrophoretic and electroosmotic contributions to streptavidin independently of one another. PMID:21319743

  10. Critical evaluation of buffering solutions for pKa determination by capillary electrophoresis.

    PubMed

    Fuguet, Elisabet; Reta, Mario; Gibert, Carme; Rosés, Martí; Bosch, Elisabeth; Ràfols, Clara

    2008-07-01

    The performance of the most common and also some other less common CE buffers has been tested for the pKa determination of several types of compounds (pyridine, amines, and phenols). The selected buffers cover a pH ranging from 3.7 to 11.8. Whereas some buffers, like acetic acid/acetate, BisTrisH+/BisTris, TrisH+/Tris, CHES/CHES-, and CAPS/CAPS- can be used with all type of analytes, others like ammonium/ammonia, butylammonium/butylammonia, ethylammonium/ethylammonia, diethylammonium/diethylammonia, and hydrogenphosphate/phosphate are not recommended because they interact with a wide range of compounds. The rest of the tested buffers (dihydrogenphosphate/hydrogenphosphate, MES/MES-, HEPES/HEPES-, and boric acid/borate) can show specific interactions depending on the nature of the analytes, and their use in some applications should be restricted. PMID:18546174

  11. Cosolvent gel-like materials from partially hydrolyzed poly(vinyl acetate)s and borax.

    PubMed

    Angelova, Lora V; Terech, Pierre; Natali, Irene; Dei, Luigi; Carretti, Emiliano; Weiss, Richard G

    2011-09-20

    A gel-like, high-viscosity polymeric dispersion (HVPD) based on cross-linked borate, partially hydrolyzed poly(vinyl acetate) (xPVAc, where x is the percent hydrolysis) is described. Unlike hydro-HVPDs prepared from poly(vinyl alcohol) (PVA) and borate, the liquid portion of these materials can be composed of up to 75% of an organic cosolvent because of the influence of residual acetate groups on the polymer backbone. The effects of the degree of hydrolysis, molecular weight, polymer and cross-linker concentrations, and type and amount of organic cosolvent on the rheological and structural properties of the materials are investigated. The stability of the systems is explored through rheological and melting-range studies. (11)B NMR and small-angle neutron scattering (SANS) are used to probe the structure of the dispersions. The addition of an organic liquid to the xPVAc-borate HVPDs results in a drastic increase in the number of cross-linked borate species as well as the agglomeration of the polymer into bundles. These effects result in an increase in the relaxation time and thermal stability of the networks. The ability to make xPVAc-borate HVPDs with very large amounts of and rather different organic liquids, with very different rheological properties that can be controlled easily, opens new possibilities for applications of PVAc-based dispersions. PMID:21848256

  12. Single pH buffer refolding screen for protein from inclusion bodies.

    PubMed

    Coutard, Bruno; Danchin, Etienne G J; Oubelaid, Rachid; Canard, Bruno; Bignon, Christophe

    2012-04-01

    We previously reported the set up of an automated test for screening the refolding of recombinant proteins expressed as inclusion bodies in Escherichia coli[1]. The screen used 96 refolding buffers and was validated with 24 proteins, 70% of which remained soluble in at least one buffer. In the present paper, we have analyzed in more detail these experimental data to see if the refolding process can be driven by general rules. Notably, we found that proteins with an acidic isoelectric point (pI) refolded in buffers the average pH of which was alkaline and conversely. In addition, the number of refolding buffers wherein a protein remained soluble increased with the difference between its pI and the average pH of the buffers in which it refolded. A trend analysis of the other variables (ionic strength, detergents, etc.) was also performed. On the basis of this analysis, we devised and validated a new refolding screen made of a single buffer for acidic proteins and a single buffer for alkaline proteins. PMID:22343064

  13. High stability buffered phase comparator

    NASA Technical Reports Server (NTRS)

    Adams, W. A.; Reinhardt, V. S. (Inventor)

    1984-01-01

    A low noise RF signal phase comparator comprised of two high stability driver buffer amplifiers driving a double balanced mixer which operate to generate a beat frequency between the two RF input signals coupled to the amplifiers from the RF sources is described. The beat frequency output from the mixer is applied to a low noise zero crossing detector which is the phase difference between the two RF inputs. Temperature stability is provided by mounting the amplifiers and mixer on a common circuit board with the active circuit elements located on one side of a circuit board and the passive circuit elements located on the opposite side. A common heat sink is located adjacent the circuit board. The active circuit elements are embedded into the bores of the heat sink which slows the effect of ambient temperature changes and reduces the temperature gradients between the active circuit elements, thus improving the cancellation of temperature effects. The two amplifiers include individual voltage regulators, which increases RF isolation.

  14. 21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Buffered penicillin powder, penicillin powder with... FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered aqueous diluent. (a) Specifications. When reconstituted, each milliliter contains penicillin G procaine...

  15. FIFO Buffer for Asynchronous Data Streams

    NASA Technical Reports Server (NTRS)

    Bascle, K. P.

    1985-01-01

    Variable-rate, asynchronous data signals from up to four measuring instruments or other sources combined in first-in/first-out (FIFO) buffer for transmission on single channel. Constructed in complementary metal-oxide-semiconductor (CMOS) logic, buffer consumes low power (only 125 mW at 5V) and conforms to aerospace standards of reliability and maintainability.

  16. UNDERSTANDING, DERIVING, AND COMPUTING BUFFER CAPACITY

    EPA Science Inventory

    Derivation and systematic calculation of buffer capacity is a topic that seems often to be neglected in chemistry courses and given minimal treatment in most texts. However, buffer capacity is very important in the chemistry of natural waters and potable water. It affects corro...

  17. Buffer Management Simulation in ATM Networks

    NASA Technical Reports Server (NTRS)

    Yaprak, E.; Xiao, Y.; Chronopoulos, A.; Chow, E.; Anneberg, L.

    1998-01-01

    This paper presents a simulation of a new dynamic buffer allocation management scheme in ATM networks. To achieve this objective, an algorithm that detects congestion and updates the dynamic buffer allocation scheme was developed for the OPNET simulation package via the creation of a new ATM module.

  18. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Buffers. 58.25-45 Section 58.25-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes...

  19. Riparian buffer transpiration and watershed scale impacts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Forested riparian buffers are prevalent throughout the Southeastern Coastal Plain Region of the United States (US). Because they make up a significant portion of the regional landscape, transpiration within these riparian buffers is believed to have an important impact on the hydrologic budget of r...

  20. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Buffers. 58.25-45 Section 58.25-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes...

  1. African American College Women's Suicide Buffers.

    ERIC Educational Resources Information Center

    Marion, Michelle S.; Range, Lillian M.

    2003-01-01

    To examine the relationships buffers may have with suicide ideation, 300 African American female college students completed measures of suicide ideation and buffers. Three variables accounted for a significant and unique portion of the variance in suicide ideation: family support, a view that suicide is unacceptable, and a collaborative religious…

  2. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Buffers. 58.25-45 Section 58.25-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes...

  3. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Buffers. 58.25-45 Section 58.25-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes...

  4. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Buffers. 58.25-45 Section 58.25-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes...

  5. Sediment retention in rangeland riparian buffers.

    PubMed

    Hook, Paul B

    2003-01-01

    Controlling nonpoint-source sediment pollution is a common goal of riparian management, but there is little quantitative information about factors affecting performance of rangeland riparian buffers. This study evaluated the influence of vegetation characteristics, buffer width, slope, and stubble height on sediment retention in a Montana foothills meadow. Three vegetation types (sedge wetland, rush transition, bunchgrass upland) were compared using twenty-six 6- x 2-m plots spanning 2 to 20% slopes. Plots were clipped moderately (10-15 cm stubble) or severely (2-5 cm stubble). Sediment (silt + fine sand) was added to simulated overland runoff 6, 2, or 1 m above the bottom of each plot. Runoff was sampled at 15-s to > 5-min intervals until sediment concentrations approached background levels. Sediment retention was affected strongly by buffer width and moderately by vegetation type and slope, but was not affected by stubble height. Mean sediment retention ranged from 63 to > 99% for different combinations of buffer width and vegetation type, with 94 to 99% retention in 6-m-wide buffers regardless of vegetation type or slope. Results suggest that rangeland riparian buffers should be at least 6 m wide, with dense vegetation, to be effective and reliable. Narrower widths, steep slopes, and sparse vegetation increase risk of sediment delivery to streams. Vegetation characteristics such as biomass, cover, or density are more appropriate than stubble height for judging capacity to remove sediment from overland runoff, though stubble height may indirectly indicate livestock impacts that can affect buffer performance. PMID:12809315

  6. Electrophoretic mobilities of erythrocytes in various buffers

    NASA Technical Reports Server (NTRS)

    Plank, L. D.; Kunze, M. E.; Todd, P. W.

    1985-01-01

    The calibration of space flight equipment depends on a source of standard test particles, this test particle of choice is the fixed erythrocyte. Erythrocytes from different species have different electrophoretic mobilities. Electrophoretic mobility depends upon zeta potential, which, in turn depends upon ionic strength. Zeta potential decreases with increasing ionic strength, so cells have high electrophoretic mobility in space electrophoresis buffers than in typical physiological buffers. The electrophoretic mobilities of fixed human, rat, and rabbit erythrocytes in 0.145 M salt and buffers of varying ionic strength, temperature, and composition, to assess the effects of some of the unique combinations used in space buffers were characterized. Several effects were assessed: glycerol or DMSO (dimethylsulfoxide) were considered for use as cryoprotectants. The effect of these substances on erythrocyte electrophoretic mobility was examined. The choice of buffer depended upon cell mobility. Primary experiments with kidney cells established the choice of buffer and cryoprotectant. A nonstandard temperature of EPM in the suitable buffer was determined. A loss of ionic strength control occurs in the course of preparing columns for flight, the effects of small increases in ionic strength over the expected low values need to be evaluated.

  7. pH buffering by metastable mineral-fluid equilibria and evolution of carbon dioxide fugacity during burial diagenesis

    SciTech Connect

    Hutcheon, I.; Shevalier, M. ); Abercrombie, H.J. )

    1993-03-01

    Numerous potential pH buffers including reactions among aqueous organic acid and carbonate species, and carbonate and silicate minerals are typically present during burial diagenesis. Buffering of pH in natural systems is a function of mass action, mass balance, and kinetic constraints. In most sedimentary basins, carbonate and silicate minerals are present in amounts sufficient to buffer pH, and the activities of aqueous species are consistent with metastable equilibrium among observed diagenetic minerals. These observations indicate that mass balance and kinetic constraints are relatively less important than mass action constraints measured by the buffer index, [beta], here defined. The buffer index ultimately dictates which buffer reaction controls pH under diagenetic conditions; buffer reactions with high [beta] values are favored over those with low values. Buffer indices for a number of potential diagenetic buffer reactions have been calculated by reaction path modeling. Heterogeneous equilibria among carbonate and silicate minerals and an aqueous phase have greater [beta] values than those for homogeneous reactions among aqueous carbonate and organic acid species. This implies that pH, calcite dissolution, and f[sub CO[sub 2

  8. A novel structure of optical buffer

    NASA Astrophysics Data System (ADS)

    Liu, AiMing; Wu, Chongqing; Gao, Huali; Gong, Yandong; Shum, Ping

    2005-02-01

    Optical buffers are critical for low packet-loss probability in future photonic packet-switched networks. In particular, they would be required to store packets during rate conversion and header processing, and to overcome the receiver's bottleneck. They would be required for queuing packets while transmitters await access to the network. In this paper, we present a novel structure of optical buffer with compact size. This kind of optical buffer is based on a collinear 3x3 fiber coupler in which three fibers are completely in the same plane and weakly coupled. A SOA is used as its nonlinear element as well as an amplifier in it.The experiment result will be also given in the paper. Storage results obtained with this novel structure optical buffer at 100Mb/s will be presented first and then its capacity is extended to higher data rates of 2.5Gb/s, more compatible with present optical networks. Storage has been observed for time up to 1.568ms(more than 32 circulations) in both cases without obvious degration. The novel structure of optical buffer could be a more compact device which makes it possible to be integrated in a chip. SOA in the buffer is used as a nonlinear element as well as an amplifier to compensate loss in the buffer loop. The buffer needs low control power for switch operation. It is easy to control 'write' and 'erase' operation because the same TOAD switch in the buffer can be used for both 'write' and 'erase' operation.

  9. Iron autoxidation in Mops and Hepes buffers.

    PubMed

    Tadolini, B

    1987-01-01

    Iron autoxidation in Mops and Hepes buffers is characterized by a lag phase that becomes shorter with increasing FeCl2 concentration and pH. During iron oxidation in these buffers a yellow colour develops in the solution. When the reaction is conducted in the presence of nitro blue tetrazolium (NBT), blue formazan is formed. Of the many OH scavengers tested, mannitol and sorbitol are most effective in inhibiting Fe2+ oxidation, yellow colour development and NBT reduction. Some inhibition was also noted with catalase. The iron product of the oxidative reaction differs from Fe3+ in its absorption spectrum and its low reactivity with thiocyanate. Similar results are obtained when iron autoxidation is studied in unbuffered solutions brought to alkaline pH with NaOH. In phosphate buffer, no lag phase is evident and the absorption spectrum of the final solution is identical to that of Fe3+ in this buffer. The iron product reacts immediately with thiocyanate. When iron oxidation is conducted in the presence of NBT the formation of formazan is almost undetectable. Of the many compounds tested only catalase inhibits iron autoxidation in this buffer. The sequence of reactions leading to iron autoxidation in Good-type buffers thus resembles that occurring in unbuffered solutions brought to alkaline pH with NaOH and greatly differs from that occurring in phosphate buffer. These results are in agreement with the observation that these buffers have very low affinity for iron. The data presented define experimental conditions where Fe2+ is substantially stable for a considerable length of time in Mops buffer. PMID:3148493

  10. Buffer-dependent pH sensitivity of the fluorescent chloride-indicator dye SPQ.

    PubMed

    Vasseur, M; Frangne, R; Alvarado, F

    1993-01-01

    The fluorescence intensity of 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ) in an N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) 2-(N-morpholino)ethanesulfonic acid (MES)-Tris(hydroxymethyl)aminomethane buffer, pH 7.0, decreased as a function of Cl- concentration and/or gluconate concentration, as expected. Contrary to expectation, however, the fluorescence intensity progressively increased as the pH decreased, independently of the presence of gluconate. Consequently, the modulation of SPQ fluorescence by commonly used buffers was investigated as a function of pH. Titration curves demonstrated SPQ quenching and yielded pK values characteristic of each buffer. from here, pH-independent Stern-Volmer constants, KQbase, were calculated for each of the morpholine derivatives, MES and 3-(N-morpholino)-2-hydroxypropanesulfonic acid. In contrast, HEPES and piperazine-N,N'-bis(2-ethanesulfonic acid), which are piperazine derivatives, exhibited an additional pH-independent "molecular" quenching constant KmQ throughout the pH range 3-10. To study chloride fluxes, therefore, what counts is the apparent Cl-Stern-Volmer constant KappCl, which is a function of both pH and buffer composition. Equations describing these relationships are presented. In conclusion, unless both pH and the buffer composition are taken into account, SPQ is unsuitable for studying the concomitant transmembrane fluxes of Cl- and H+. PMID:8381589

  11. Comparison of alternative buffers for use with a new live oral cholera vaccine, Peru-15, in outpatient volunteers.

    PubMed

    Sack, D A; Shimko, J; Sack, R B; Gomes, J G; MacLeod, K; O'Sullivan, D; Spriggs, D

    1997-06-01

    During development of Peru-15, a new live oral vaccine for cholera, the role of buffer needed to be evaluated. Generally, oral bacterial vaccines are acid labile and need to be administered by using a formulation which protects them from gastric acid. We compared three different buffers for use with Peru-15, including a standard bicarbonate-ascorbic acid buffer, Alka-Seltzer, and a new electrolyte-rice buffer, CeraVacx. Saline served as the control. Thirty-nine healthy adult volunteers received Peru-15 (10(8) CFU) with one of the three buffers or saline in a double-masked study. The volunteers were monitored for symptoms for 7 days after the dose, serum was tested for antibody responses by vibriocidal antibody and immunoglobulin G antitoxin enzyme-linked immunosorbent assays, and stool samples were tested for excretion of the vaccine strain. Side effects were minimal in all groups. All 30 volunteers who took Peru-15 with a buffer showed significant rises in vibriocidal antibody titer. The magnitude of the rises was higher in the CeraVacx group than in the other two buffer groups. Four of nine volunteers who took the vaccine with saline also showed increased titers, but they were lower than those in any of the three buffer groups. Excretion of the vaccine strain was similar in the buffer groups, but excretion was not associated with the magnitude of the vibriocidal responses. Excretion of Peru-15 was not detected in the saline group. We conclude that buffer does amplify the serological response to Peru-15 and that CeraVacx may provide benefits not provided by other buffers. PMID:9169739

  12. Comparison of alternative buffers for use with a new live oral cholera vaccine, Peru-15, in outpatient volunteers.

    PubMed Central

    Sack, D A; Shimko, J; Sack, R B; Gomes, J G; MacLeod, K; O'Sullivan, D; Spriggs, D

    1997-01-01

    During development of Peru-15, a new live oral vaccine for cholera, the role of buffer needed to be evaluated. Generally, oral bacterial vaccines are acid labile and need to be administered by using a formulation which protects them from gastric acid. We compared three different buffers for use with Peru-15, including a standard bicarbonate-ascorbic acid buffer, Alka-Seltzer, and a new electrolyte-rice buffer, CeraVacx. Saline served as the control. Thirty-nine healthy adult volunteers received Peru-15 (10(8) CFU) with one of the three buffers or saline in a double-masked study. The volunteers were monitored for symptoms for 7 days after the dose, serum was tested for antibody responses by vibriocidal antibody and immunoglobulin G antitoxin enzyme-linked immunosorbent assays, and stool samples were tested for excretion of the vaccine strain. Side effects were minimal in all groups. All 30 volunteers who took Peru-15 with a buffer showed significant rises in vibriocidal antibody titer. The magnitude of the rises was higher in the CeraVacx group than in the other two buffer groups. Four of nine volunteers who took the vaccine with saline also showed increased titers, but they were lower than those in any of the three buffer groups. Excretion of the vaccine strain was similar in the buffer groups, but excretion was not associated with the magnitude of the vibriocidal responses. Excretion of Peru-15 was not detected in the saline group. We conclude that buffer does amplify the serological response to Peru-15 and that CeraVacx may provide benefits not provided by other buffers. PMID:9169739

  13. Marriage a Buffer Against Drinking Problems?

    MedlinePlus

    ... news/fullstory_158887.html Marriage a Buffer Against Drinking Problems? Study found protective benefit for both men ... News) -- Married people are less likely to have drinking problems than single people, and that protective effect ...

  14. Marriage a Buffer Against Drinking Problems?

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_158887.html Marriage a Buffer Against Drinking Problems? Study found protective ... aware of the potentially important protective effects of marriage on alcohol problems, our study puts this observation ...

  15. A MICROPROCESSOR ASCII CHARACTER BUFFERING SYSTEM

    EPA Science Inventory

    A microprocessor buffering system (MBS) was developed at the Environmental Monitoring and Support Laboratory -Cincinnati (EMSL-CI) to provide an efficient transfer for serial ASCII information between intelligent instrument systema and a Data General NOVA laboratory automation co...

  16. Optical imaging: Ultrafast buffering by molecular gas

    NASA Astrophysics Data System (ADS)

    Hertz, Edouard; Lavorel, Bruno; Faucher, Olivier

    2011-02-01

    A simple molecular gas sample can be used to achieve ultrafast optical buffering in two-dimensional optical imaging, thus serving as a promising extension of the well-developed liquid-crystal display technology.

  17. Formation Buffering Potential Pertaining to Geological Storage of Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Ellis, B. R.; Peters, C. A.; Buschkuehle, M.

    2007-12-01

    One promising strategy for decreasing CO2 emissions to the atmosphere is carbon capture and storage in deep saline formations. Modeling efforts and the experimental measurements that support these efforts are critical to determining the fate of injected CO2. The focus of this work is CO2-water-rock interactions as they pertain to formation buffering potential. PHREEQC was used to model pH evolution in siliciclastic and carbonate rocks after simulated injection of CO2. The initial mineral and formation water compositions were determined from analysis of core samples and brines from several formations in the Alberta sedimentary basin in western Canada. Simulation parameters correspond to injection conditions of 50°C, CO2 pressure of 100 bar and high ionic strength. Results indicate that the carbonate formations have a higher buffering potential relative to siliciclastic formations. Considerable variability of acid-catalyzed reactions among formations with similar mineralogical compositions was also observed. To assess the effect of grain coating by clay minerals, a comparative simulation was performed with kaolinite as the dominant mineral in contact with the pore fluids. Results from this simulation showed a pronounced retardation in pH buffering reaction kinetics. This emphasizes the importance for differentiating between mineral abundance and accessibility in model calculations when clay coatings may obscure contact between pore fluids and potentially reactive minerals.

  18. Buffer layer for thin film structures

    DOEpatents

    Foltyn, Stephen R.; Jia, Quanxi; Arendt, Paul N.; Wang, Haiyan

    2006-10-31

    A composite structure including a base substrate and a layer of a mixture of strontium titanate and strontium ruthenate is provided. A superconducting article can include a composite structure including an outermost layer of magnesium oxide, a buffer layer of strontium titanate or a mixture of strontium titanate and strontium ruthenate and a top-layer of a superconducting material such as YBCO upon the buffer layer.

  19. Buffer layer for thin film structures

    DOEpatents

    Foltyn, Stephen R.; Jia, Quanxi; Arendt, Paul N.; Wang, Haiyan

    2010-06-15

    A composite structure including a base substrate and a layer of a mixture of strontium titanate and strontium ruthenate is provided. A superconducting article can include a composite structure including an outermost layer of magnesium oxide, a buffer layer of strontium titanate or a mixture of strontium titanate and strontium ruthenate and a top-layer of a superconducting material such as YBCO upon the buffer layer.

  20. Frog striated muscle is permeable to hydroxide and buffer anions.

    PubMed

    Venosa, R A; Kotsias, B A; Horowicz, P

    1994-04-01

    Hydroxide, bicarbonate and buffer anion permeabilities in semitendinosus muscle fibers of Rana pipiens were measured. In all experiments, the fibers were initially equilibrated in isotonic, high K2SO4 solutions at pHo = 7.2 buffered with phosphate. Two different methods were used to estimate permeabilities: (i) membrane potential changes were recorded in response to changes in external ion concentrations, and (ii) intracellular pH changes were recorded in response to changes in external concentrations of ions that alter intracellular pH. Constant field equations were used to calculate relative or absolute permeabilities. In the first method, to increase the size of the membrane potential change produced by a sudden change in anion entry, external K+ was replaced by Cs+ prior to changes of the anion under study. At constant external Cs+ activity, a hyperpolarization results from increasing external pH from 7.2 to 10.0 or higher, using either CAPS (3-[cyclohexylamino]-1-propanesulfonic acid) or CHES (2-[N-cyclohexylamino]-ethanesulfonic acid) as buffer. For each buffer, the protonated form is a zwitterion of zero net charge and the nonprotonated form is an anion. Using reported values of H+ permeability, calculations show that the reduction in [H+]o cannot account for the hyperpolarizations produced by alkaline solutions. Membrane hyperpolarization increases with increasing total external buffer concentration at constant external pH, and with increasing external pH at constant external buffer anion concentration. Taken together, these observations indicate that both OH- and buffer anions permeate the surface membrane. The following relative permeabilities were obtained at pHo = 10.0 +/- 0.3: (POH/PK) = 890 +/- 150, (PCAPS/PK) = 12 +/- 2, (PCHES/PK) = 5.3 +/- 0.9, and (PNO3/PK) = 4.7 +/- 0.5. PNO3/PK was independent of pHo up to 10.75. At pHo = 9.6, (PHCO3/PK) = 0.49 +/- 0.03; at pHo = 8.9, (PCl/PK) = 18 +/- 2 and at pHo = 7.1, (PHEPES/PK) = 20 +/- 2. In the second

  1. A Proton Buffering Role for Silica in Diatoms

    NASA Astrophysics Data System (ADS)

    Milligan, Allen J.; Morel, François M. M.

    2002-09-01

    For 40 million years, diatoms have dominated the reverse weathering of silica on Earth. These photosynthetic protists take up dissolved silicic acid from the water and precipitate opaline silica to form their cell wall. We show that the biosilica of diatoms is an effective pH buffer, enabling the enzymatic conversion of bicarbonate to CO2, an important step in inorganic carbon acquisition by these organisms. Because diatoms are responsible for one-quarter of global primary production and for a large fraction of the carbon exported to the deep sea, the global cycles of Si and C may be linked mechanistically.

  2. Buffer regulation of calcium puff sequences

    NASA Astrophysics Data System (ADS)

    Fraiman, Daniel; Ponce Dawson, Silvina

    2014-02-01

    Puffs are localized Ca2 + signals that arise in oocytes in response to inositol 1,4,5-trisphosphate (IP3). They are the result of the liberation of Ca2 + from the endoplasmic reticulum through the coordinated opening of IP3 receptor/channels clustered at a functional release site. The presence of buffers that trap Ca2 + provides a mechanism that enriches the spatio-temporal dynamics of cytosolic calcium. The expression of different types of buffers along the cell's life provides a tool with which Ca2 + signals and their responses can be modulated. In this paper we extend the stochastic model of a cluster of IP3R-Ca2 + channels introduced previously to elucidate the effect of buffers on sequences of puffs at the same release site. We obtain analytically the probability laws of the interpuff time and of the number of channels that participate of the puffs. Furthermore, we show that under typical experimental conditions the effect of buffers can be accounted for in terms of a simple inhibiting function. Hence, by exploring different inhibiting functions we are able to study the effect of a variety of buffers on the puff size and interpuff time distributions. We find the somewhat counter-intuitive result that the addition of a fast Ca2 + buffer can increase the average number of channels that participate of a puff.

  3. Social buffering: relief from stress and anxiety

    PubMed Central

    Kikusui, Takefumi; Winslow, James T; Mori, Yuji

    2006-01-01

    Communication is essential to members of a society not only for the expression of personal information, but also for the protection from environmental threats. Highly social mammals have a distinct characteristic: when conspecific animals are together, they show a better recovery from experiences of distress. This phenomenon, termed ‘social buffering’, has been found in rodents, birds, non-human primates and also in humans. This paper reviews classical findings on social buffering and focuses, in particular, on social buffering effects in relation to neuroendocrine stress responses. The social cues that transmit social buffering signals, the neural mechanisms of social buffering and a partner's efficacy with respect to social buffering are also detailed. Social contact appears to have a very positive influence on the psychological and the physiological aspects of social animals, including human beings. Research leading towards further understanding of the mechanisms of social buffering could provide alternative medical treatments based on the natural, individual characteristics of social animals, which could improve the quality of life. PMID:17118934

  4. Natural factors and mining activity bearings on the water quality of the Choapa basin, North Central Chile: insights on the role of mafic volcanic rocks in the buffering of the acid drainage process.

    PubMed

    Parra, Amparo; Oyarzún, Jorge; Maturana, Hugo; Kretschmer, Nicole; Meza, Francisco; Oyarzún, Ricardo

    2011-10-01

    This contribution analyzes water chemical data for the Choapa basin, North Central Chile, for the period 1980-2004. The parameters considered are As, Cu Fe, pH, EC, SO₄⁻², Cl⁻¹, and HCO[Formula: see text], from samples taken in nine monitoring stations throughout the basin. Results show rather moderate contents of As, Cu, and Fe, with the exception of the Cuncumén River and the Aucó creek, explained by the influence of the huge porphyry copper deposit of Los Pelambres and by the presence of mining operations, respectively. When compared against results obtained in previous researches at the neighboring Elqui river basin, which host the El Indio Au-Cu-As district, a much reduced grade of pollution is recognized for the Choapa basin. Considering the effect of acid rock drainage (ARD)-related Cu contents on the fine fraction of the sediments of both river basins, the differences recorded are even more striking. Although the Los Pelambres porphyry copper deposit, on the headwaters of the Choapa river basin, is between one and two orders of magnitude bigger than El Indio, stream water and sediments of the former exhibit significantly lower copper contents than those of the latter. A main factor which may explain these results is the smaller degree of H( + )-metasomatism on the host rocks of the Los Pelambres deposit, where mafic andesitic volcanic rocks presenting propylitic hydrothermal alteration are dominant. This fact contrast with the highly altered host rocks of El Indio district, where most of them have lost their potential to neutralize ARD. PMID:21170583

  5. Low noise buffer amplifiers and buffered phase comparators for precise time and frequency measurement and distribution

    NASA Technical Reports Server (NTRS)

    Eichinger, R. A.; Dachel, P.; Miller, W. H.; Ingold, J. S.

    1982-01-01

    Extremely low noise, high performance, wideband buffer amplifiers and buffered phase comparators were developed. These buffer amplifiers are designed to distribute reference frequencies from 30 KHz to 45 MHz from a hydrogen maser without degrading the hydrogen maser's performance. The buffered phase comparators are designed to intercompare the phase of state of the art hydrogen masers without adding any significant measurement system noise. These devices have a 27 femtosecond phase stability floor and are stable to better than one picosecond for long periods of time. Their temperature coefficient is less than one picosecond per degree C, and they have shown virtually no voltage coefficients.

  6. Temperature buffer test design, instrumentation and measurements

    NASA Astrophysics Data System (ADS)

    Sandén, Torbjörn; Goudarzi, Reza; de Combarieu, Michel; Åkesson, Mattias; Hökmark, Harald

    The Temperature Buffer Test, TBT, is a heated full-scale field experiment carried out jointly by ANDRA and SKB at the SKB Äspö Hard Rock Laboratory in Southeast Sweden. An existing 8 m deep, 1.8 m diameter KBS-3-type deposition hole located at -420 m level has been selected for the test. The objectives are to improve the general understanding of Thermo-Hydro-Mechanical, THM, behavior of buffer materials submitted to severe thermal conditions with temperatures well over 100 °C during water uptake of partly saturated bentonite-based buffer materials, and to check, in due time, their properties after water saturation. The test includes two carbon steel heating canisters each 3 m high and 0.6 m diameter, surrounded by 0.6 m of buffer material. There is a 0.2 m thick sand shield between the upper heater and the surrounding bentonite, while the lower heater is surrounded by bentonite only. On top of the stack of bentonite blocks is a confining plug anchored to the rock. In the slot between buffer and rock wall is a sand filter equipped with pipes to control the water pressure at the boundary, which is seldom done with an EBS in situ experiment. Both heater mid-height planes are densely instrumented in order to follow, with direct or indirect methods, buffer THM evolution. Temperature, relative humidity, stress and pore pressure have been monitored since the test start in March 2003. Total water inflow is also monitored. Firstly, the present paper describes the test design, the instrumentation, the plug anchoring system and the system for water boundary pressure control. Second, having described the test, the paper shows different measurements that illustrate evolution of temperature, saturation, suction and swelling pressure in the upper and the lower buffer.

  7. Biochar contribution to soil pH buffer capacity

    NASA Astrophysics Data System (ADS)

    Tonutare, Tonu; Krebstein, Kadri; Utso, Maarius; Rodima, Ako; Kolli, Raimo; Shanskiy, Merrit

    2014-05-01

    Biochar as ecologically clean and stable form of carbon has complex of physical and chemical properties which make it a potentially powerful soil amendment (Mutezo, 2013). Therefore during the last decade the biochar application as soil amendment has been a matter for a great number of investigations. For the ecological viewpoint the trend of decreasing of soil organic matter in European agricultural land is a major problem. Society is faced with the task to find possibilities to stabilize or increase soil organic matter content in soil and quality. The availability of different functional groups (e.g. carboxylic, phenolic, acidic, alcoholic, amine, amide) allows soil organic matter to buffer over a wide range of soil pH values (Krull et al. 2004). Therefore the loss of soil organic matter also reduces cation exchange capacity resulting in lower nutrient retention (Kimetu et al. 2008). Biochar can retain elements in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil. There are lack of investigations about the effect of biochar to soil pH buffering properties, The aim of our investigation was to investigate the changes in soil pH buffer capacity in a result of addition of carbonizated material to temperate region soils. In the experiment different kind of softwood biochars, activated carbon and different soil types with various organic matter and pH were used. The study soils were Albeluvisols, Leptosols, Cambisols, Regosols and Histosols . In the experiment the series of the soil: biochar mixtures with the biochar content 0 to 100% were used. The times of equiliberation between solid and liquid phase were from 1 to 168 hours. The suspension of soil: biochar mixtures was titrated with HCl solution. The titration curves were established and pH buffer capacities were calculated for the pH interval from 3.0 to 10.0. The results demonstrate the dependence of pH buffer capacity from soil type

  8. Mechanisms of drug release in citrate buffered HPMC matrices.

    PubMed

    Pygall, Samuel R; Kujawinski, Sarah; Timmins, Peter; Melia, Colin D

    2009-03-31

    Few studies report the effects of alkalizing buffers in HPMC matrices. These agents are incorporated to provide micro-environmental buffering, protection of acid-labile ingredients, or pH-independent release of weak acid drugs. In this study, the influence of sodium citrate on the release kinetics, gel layer formation, internal gel pH and drug release mechanism was investigated in HPMC 2910 and 2208 (Methocel E4M and K4M) matrices containing 10% felbinac 39% HPMC, dextrose and sodium citrate. Matrix dissolution at pH 1.2 and pH 7.5 resulted in complex release profiles. HPMC 2910 matrices exhibited biphasic release, with citrate increasing the immediate release phase (<60min) and reducing the extended release. HPMC 2208 matrices were accelerated, but without the loss of extended release characteristics. Studies of early gel layer formation suggested gel barrier disruption and enhanced liquid penetration. pH modification of the gel layer was transitory (<2h) and corresponded temporally with the immediate release phase. Results suggest that in HPMC 2910 matrices, high initial citrate concentrations within the gel layer suppress particle swelling, interfere with diffusion barrier integrity, but are lost rapidly whereupon drug solubility reduces and the diffusion barrier recovers. These Hofmeister or osmotic-mediated effects are better resisted by the less methoxylated HPMC 2208. PMID:19100822

  9. Equilibrium Studies of Dibutyltin(IV)-Zwitterionic Buffer Complexation.

    PubMed

    El-Gahami, M A; Albishri, H M

    2013-01-01

    Equilibrium studies in aqueous solution are reported for dibutyltin(IV) (DBT) complexes of the zwitterionic buffers "Good's buffers" Mes and Mops. Stoichiometric and formation constants of the complexes formed were determined at different temperatures and ionic strength 0.1 mol·L(-1) NaNO3. The results show that the best fit of the titration curves were obtained when the complexes ML, MLH-1, MLH-2 and MLH-3 were considered beside the hydrolysis product of the dibutyltin(IV) cation. The thermodynamic parameters ΔH (o), ΔS (o) and ΔG (o) calculated from the temperature dependence of the formation constant of the dibutyltin(IV) complexes with 2-(N-morpholino)ethanesulfonic acid (Mes) and 3-(N-mor-pholino)-propanesulfonic acid (Mops) were investigated. The effect of dioxane as a solvent on the formation constants of DBT-Mes and DBT-Mops complexes decrease linearly with the increase of dioxane proportion in the medium. The concentration distribution of the various complexes species was evaluated as a function of pH. PMID:24273357

  10. 12 CFR 3.11 - Capital conservation buffer and countercyclical capital buffer amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... or Federal savings association under subparts H and I of this part; 12 CFR 5.46, 12 CFR part 5, subpart E; 12 CFR part 6. (b) Countercyclical capital buffer amount. (1) General. An advanced approaches... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Capital conservation buffer and...

  11. 12 CFR 324.11 - Capital conservation buffer and countercyclical capital buffer amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    .... Additional limitations on distributions may apply to an FDIC-supervised institution under 12 CFR 303.241 and... 12 Banks and Banking 5 2014-01-01 2014-01-01 false Capital conservation buffer and countercyclical capital buffer amount. 324.11 Section 324.11 Banks and Banking FEDERAL DEPOSIT INSURANCE...

  12. 12 CFR 217.11 - Capital conservation buffer and countercyclical capital buffer amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... distributions. Additional limitations on distributions may apply to a Board-regulated institution under 12 CFR 225.4, 12 CFR 225.8, and 12 CFR 263.202. (b) Countercyclical capital buffer amount. (1) General. An... 12 Banks and Banking 2 2014-01-01 2014-01-01 false Capital conservation buffer and...

  13. Undergraduate Chemistry Students' Perceptions of and Misconceptions about Buffers and Buffer Problems

    ERIC Educational Resources Information Center

    Orgill, MaryKay; Sutherland, Aynsley

    2008-01-01

    Both upper- and lower-level chemistry students struggle with understanding the concept of buffers and with solving corresponding buffer problems. While it might be reasonable to expect general chemistry students to struggle with this abstract concept, it is surprising that upper-level students in analytical chemistry and biochemistry continue to…

  14. Nonlinear spelling in graphemic buffer deficit.

    PubMed

    Schubert, Teresa; Nickels, Lyndsey

    2015-01-01

    In this paper, we describe a case of nonlinear spelling and its implications for theories of the graphemic buffer. C.T.J., an individual with an acquired deficit of the graphemic buffer, often wrote the letters of his responses in a nonlinear temporal order when writing to dictation. The spatial ordering of the letters was maintained: Letters in the later positions of the words were written towards the right side of the response, even when written before letters in earlier positions. This unusual phenomenon has been briefly reported in three prior cases but this study provides the most detailed analysis of the phenomenon to date. We specifically contend that the decoupling of the temporal and spatial aspects of spelling is difficult to reconcile with competitive queuing accounts of the graphemic buffer. PMID:27355609

  15. PREDICTION OF BUFFER CATALYSIS IN FIELD AND LABORATORY STUDIES OF POLLUTANT HYDROLYSIS REACTIONS

    EPA Science Inventory

    A mathematical model, based on application of the Bronsted equations for general acid-base catalysis, has been developed for use in forecasting the maximum contribution of buffer catalysis in pollutant hydrolysis reactions. The predictive capacity of the model is utilized to exam...

  16. Evaluation of a newly developed triple buffered peptone broth for detection of Salmonella in broiler feed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lactose broth (LB) and buffered peptone (BP) are used as pre-enrichment media to recover Salmonella from feed. Bacterial utilization of feed carbohydrates results in the production of acidic byproducts causing a drop in the media pH which can injure or kill Salmonella and yield false negative resul...

  17. O-buffer: a framework for sample-based graphics.

    PubMed

    Qu, Huamin; Kaufman, Arie E

    2004-01-01

    We present an innovative modeling and rendering primitive, called the O-buffer, as a framework for sample-based graphics. The 2D or 3D O-buffer is, in essence, a conventional image or a volume, respectively, except that samples are not restricted to a regular grid. A sample position in the O-buffer is recorded as an offset to the nearest grid point of a regular base grid (hence the name O-buffer). The O-buffer can greatly improve the expressive power of images and volumes. Image quality can be improved by storing more spatial information with samples and by avoiding multiple resamplings. It can be exploited to represent and render unstructured primitives, such as points, particles, and curvilinear or irregular volumes. The O-buffer is therefore a unified representation for a variety of graphics primitives and supports mixing them in the same scene. It is a semiregular structure which lends itself to efficient construction and rendering. O-buffers may assume a variety of forms including 2D O-buffers, 3D O-buffers, uniform O-buffers, nonuniform O-buffers, adaptive O-buffers, layered-depth O-buffers, and O-buffer trees. We demonstrate the effectiveness of the O--buffer in a variety of applications, such as image-based rendering, point sample rendering, and volume rendering. PMID:18579969

  18. Printing without Waiting: Buffers and Spoolers.

    ERIC Educational Resources Information Center

    Phillips, Brian

    1989-01-01

    Describes two methods to increase the speed of printing on microcomputers: (1) buffers, which are external storage devices used to temporarily store data bound for the printer; and (2) spoolers, which are software programs used to capture printer output and send it to the computer's memory or to a disk file. (LRW)

  19. Buffer layers on biaxially textured metal substrates

    DOEpatents

    Shoup, Shara S.; Paranthamam, Mariappan; Beach, David B.; Kroeger, Donald M.; Goyal, Amit

    2001-01-01

    A method is disclosed for forming a biaxially textured buffer layer on a biaxially oriented metal substrate by using a sol-gel coating technique followed by pyrolyzing/annealing in a reducing atmosphere. This method is advantageous for providing substrates for depositing electronically active materials thereon.

  20. A Discovery Chemistry Experiment on Buffers

    ERIC Educational Resources Information Center

    Kulevich, Suzanne E.; Herrick, Richard S.; Mills, Kenneth V.

    2014-01-01

    The Holy Cross Chemistry Department has designed and implemented an experiment on buffers as part of our Discovery Chemistry curriculum. The pedagogical philosophy of Discovery Chemistry is to make the laboratory the focal point of learning for students in their first two years of undergraduate instruction. We first pose questions in prelaboratory…

  1. Body Buffer Zone and Proxemics in Blocking.

    ERIC Educational Resources Information Center

    Stockwell, John C.; Bahs, Clarence W.

    This paper investigates the effect of personal body buffer zones on compositional arrangements staged by novice directors. Relationships between directors' concepts of personal space and their projection of its dimensions into staging are studied through the use of a variety of proximity measures--distance, area angles of approach, and physical…

  2. Baroreflex buffering and susceptibility to vasoactive drugs

    NASA Technical Reports Server (NTRS)

    Jordan, Jens; Tank, Jens; Shannon, John R.; Diedrich, Andre; Lipp, Axel; Schroder, Christoph; Arnold, Guy; Sharma, Arya M.; Biaggioni, Italo; Robertson, David; Luft, Friedrich C.

    2002-01-01

    BACKGROUND: The overall effect of vasoactive drugs on blood pressure is determined by a combination of the direct effect on vascular tone and an indirect baroreflex-mediated effect, a baroreflex buffering of blood pressure. Differences in baroreflex function affect the responsiveness to vasoactive medications, particularly baroreflex buffering of blood pressure; however, the magnitude is not known. METHODS AND RESULTS: We characterized baroreflex function and responses to vasoactive drugs in patients with idiopathic orthostatic intolerance, patients with essential hypertension, patients with monogenic hypertension and brachydactyly, patients with multiple system atrophy, and control subjects. We used phenylephrine sensitivity during ganglionic blockade as a measure of baroreflex buffering. Phenylephrine (25 microg) increased systolic blood pressure 6+/-1.6 mm Hg in control subjects, 6+/-1.1 mm Hg in orthostatic intolerance patients, 18+/-3.9 mm Hg in patients with essential hypertension, 31+/-3.4 mm Hg in patients with monogenic hypertension, and 25+/-3.4 mm Hg in patients with multiple system atrophy. Similar differences in sensitivities between groups were observed with nitroprusside. The sensitivity to vasoactive drugs was highly correlated with baroreflex buffering function and to a lesser degree with baroreflex control of heart rate. In control subjects, sensitivities to nitroprusside and phenylephrine infusions were correlated with baroreflex heart rate control and sympathetic nerve traffic. CONCLUSIONS: Our findings are consistent with an important effect of baroreflex blood pressure buffering on the sensitivity to vasoactive drugs. They suggest that even moderate changes in baroreflex function may have a substantial effect on the sensitivity to vasoactive medications.

  3. Electrochemical behaviour of silver in borate buffer solutions

    NASA Astrophysics Data System (ADS)

    Zaky, Ayman M.; Assaf, Fawzi H.; Abd El Rehim, Sayed S.; Mohamed, Basheer M.

    2004-01-01

    The electrochemical behaviour of Ag in aqueous 0.15 M borax and 0.15 M boric acid buffer solution was studied under various conditions using cyclic voltammetry and potentiostatic techniques. It was found that the anodic polarization curve of Ag in borate buffer solution was characterized by the appearance of two potential regions, active and passive, prior to the oxygen evolution reaction. The active potential region was characterized by the appearance of three anodic peaks, the first two peaks A 1 and A 2 correspond to the oxidation of Ag and formation of [Ag(OH) 2] - soluble compound and a passive film of Ag 2O on the electrode surface. The third anodic peak corresponds to the conversion of both [Ag(OH) 2] - and Ag 2O to Ag 2O 2. X-ray diffraction patterns confirmed the existence of Ag 2O and Ag 2O 2 passive layers on the electrode surface potentiodynamically polarized up to 800 mV. Potentiostatic current transient measurements showed that the formation of Ag 2O and Ag 2O 2 involves a nucleation and growth mechanism under diffusion control.

  4. Synthesis of Gold Nanoparticles with Buffer-Dependent Variations of Size and Morphology in Biological Buffers

    NASA Astrophysics Data System (ADS)

    Ahmed, Syed Rahin; Oh, Sangjin; Baba, Rina; Zhou, Hongjian; Hwang, Sungu; Lee, Jaebeom; Park, Enoch Y.

    2016-02-01

    The demand for biologically compatible and stable noble metal nanoparticles (NPs) has increased in recent years due to their inert nature and unique optical properties. In this article, we present 11 different synthetic methods for obtaining gold nanoparticles (Au NPs) through the use of common biological buffers. The results demonstrate that the sizes, shapes, and monodispersity of the NPs could be varied depending on the type of buffer used, as these buffers acted as both a reducing agent and a stabilizer in each synthesis. Theoretical simulations and electrochemical experiments were performed to understand the buffer-dependent variations of size and morphology exhibited by these Au NPs, which revealed that surface interactions and the electrostatic energy on the (111) surface of Au were the determining factors. The long-term stability of the synthesized NPs in buffer solution was also investigated. Most NPs synthesized using buffers showed a uniquely wide range of pH stability and excellent cell viability without the need for further modifications.

  5. Synthesis of Gold Nanoparticles with Buffer-Dependent Variations of Size and Morphology in Biological Buffers.

    PubMed

    Ahmed, Syed Rahin; Oh, Sangjin; Baba, Rina; Zhou, Hongjian; Hwang, Sungu; Lee, Jaebeom; Park, Enoch Y

    2016-12-01

    The demand for biologically compatible and stable noble metal nanoparticles (NPs) has increased in recent years due to their inert nature and unique optical properties. In this article, we present 11 different synthetic methods for obtaining gold nanoparticles (Au NPs) through the use of common biological buffers. The results demonstrate that the sizes, shapes, and monodispersity of the NPs could be varied depending on the type of buffer used, as these buffers acted as both a reducing agent and a stabilizer in each synthesis. Theoretical simulations and electrochemical experiments were performed to understand the buffer-dependent variations of size and morphology exhibited by these Au NPs, which revealed that surface interactions and the electrostatic energy on the (111) surface of Au were the determining factors. The long-term stability of the synthesized NPs in buffer solution was also investigated. Most NPs synthesized using buffers showed a uniquely wide range of pH stability and excellent cell viability without the need for further modifications. PMID:26847691

  6. Spacecraft optical disk recorder memory buffer control

    NASA Technical Reports Server (NTRS)

    Hodson, Robert F.

    1993-01-01

    This paper discusses the research completed under the NASA-ASEE summer faculty fellowship program. The project involves development of an Application Specific Integrated Circuit (ASIC) to be used as a Memory Buffer Controller (MBC) in the Spacecraft Optical Disk System (SODR). The SODR system has demanding capacity and data rate specifications requiring specialized electronics to meet processing demands. The system is being designed to support Gigabit transfer rates with Terabit storage capability. The complete SODR system is designed to exceed the capability of all existing mass storage systems today. The ASIC development for SODR consist of developing a 144 pin CMOS device to perform format conversion and data buffering. The final simulations of the MBC were completed during this summer's NASA-ASEE fellowship along with design preparations for fabrication to be performed by an ASIC manufacturer.

  7. Buffered explosions in steel pressure vessels

    SciTech Connect

    Glenn, L.A.

    1986-01-01

    The impulse delivered to the walls of a vessel containing an explosion will increase if material is placed between the walls and the charge. If the impulse application time is small in compared with the eigenperiod of the vessel, the wall stress will increase in direct proportion to the impulse. Conversely, if the application period can be extended beyond half the eigenperiod, the peak stress will be proportional to the ratio of the impulse to the delivery period. With powder or granular buffers, it is possible for the delivery period to increase faster than the impulse as the buffer mass is increased. This is the reason why certain powders, or porous materials, can provide stress reduction even below that observed by evacuating the space between the walls and the explosive. If the buffer material is to serve as an effective mitigator, it must collapse on shock loading to a final density that depends only weakly on pressure; the criterion is that the wave speed in the material that impacts the wall must be small comparison with the impact (particle) speed. This behavior apparently occurs with salt, at least for modest values of the charge parameter, but to a lesser extent with snow under the same conditions. The vermiculite data are comparable to the salt in the charge paramete region where the two overlap; with increasing explosive, however, the vermiculite appears to behave like the snow and its effectiveness as a mitigator rapidly diminishes. It is also clear that once the wave speed criterion is seriously violated, the use of a powder buffer will result in a higher wall stress than if only air filled the space between walls and charge. 5 refs.

  8. Impurity in buffer substances mimics the effects of ATP on soluble 5'-nucleotidase.

    PubMed

    Le Hir, M

    1991-01-01

    An impurity, probably an anion, present in some batches of the buffer substances 4-(2-hydroxyethyl) piperazine-1-ethanesulfonic acid (HEPES), 2-morpholinoethane sulfonic acid (Mes) and piperazine-1,4-bis(2-ethane sulfonic acid (Pipes), activates the soluble 5'-nucleotidase from rat kidney. The affinity of the enzyme for 5'-IMP and the Vmax were both increased by the unidentified activator. ATP and 2,3-diphosphoglycerate, known activators of the soluble 5'-nucleotidase, had no effect if the incubation media were buffered with batches containing high concentrations of the activating impurity. These results suggest that the impurity interacts with the soluble 5'-nucleotidase at the same site as ATP and 2,3-diphosphoglycerate, however with a much higher affinity than these two compounds. It is possible that the same impurity might interfere with other proteins for which ATP is a substrate or a ligand. PMID:1668552

  9. META-ANALYSIS OF NITROGEN REMOVAL IN RIPARIAN BUFFERS

    EPA Science Inventory

    Riparian buffer zones, the vegetated region adjacent to streams and wetlands, are thought to be effective at intercepting and controlling nitrogen loads entering water bodies. Riparian buffer width may be positively related to nitrogen removal effectiveness by influencing nitrog...

  10. Cheese whey as substrate of batch hydrogen production: effect of temperature and addition of buffer.

    PubMed

    Muñoz-Páez, K M; Poggi-Varaldo, H M; García-Mena, J; Ponce-Noyola, M T; Ramos-Valdivia, A C; Barrera-Cortés, J; Robles-González, I V; Ruiz-Ordáz, N; Villa-Tanaca, L; Rinderknecht-Seijas, N

    2014-05-01

    The aim of this work was to evaluate the effect of buffer addition and process temperature (ambient and 35°C) on H2 production in batch fermentation of cheese whey (CW). When the H2 production reached a plateau, the headspace of the reactors were flushed with N2 and reactors were re-incubated. Afterwards, only the reactors with phosphate buffer showed a second cycle of H2 production and 48% more H2 was obtained. The absence of a second cycle in non-buffered reactors could be related to a lower final pH than in the buffered reactors; the low pH could drive the fermentation to solvents production. Indeed a high solvent production was observed in non-buffered bioreactors as given by low ρ ratios (defined as the ratio between sum of organic acid production and sum of solvents production). Regarding the process temperatures, no significant difference between the H2 production of reactors incubated at ambient temperature and at 35°C was described. After flushing the headspace of bioreactors with N2 at the end of the second cycle, the H2 production did not resume (in all reactors). PMID:24821747

  11. Patterns of sediment and phosphorus accumulation in a riparian buffer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian buffers prevent sediment and phosphorus (P) from reaching streams, but their accumulation in buffers is seldom measured. This study's objectives were to determine accumulations of sediment and P in a multi-species riparian buffer, and characterize spatial-temporal patterns of P in soil wate...

  12. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Boundary pillars and buffer zones. 3931... EXPLORATION AND LEASES Plans of Development and Exploration Plans § 3931.100 Boundary pillars and buffer zones... prior written consent or on the BLM's order. For in-situ operations, a 50-foot buffer zone from...

  13. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Boundary pillars and buffer zones. 3931... EXPLORATION AND LEASES Plans of Development and Exploration Plans § 3931.100 Boundary pillars and buffer zones... prior written consent or on the BLM's order. For in-situ operations, a 50-foot buffer zone from...

  14. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Boundary pillars and buffer zones. 3931... AND LEASES Plans of Development and Exploration Plans § 3931.100 Boundary pillars and buffer zones. (a... prior written consent or on the BLM's order. For in-situ operations, a 50-foot buffer zone from...

  15. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Boundary pillars and buffer zones. 3931... EXPLORATION AND LEASES Plans of Development and Exploration Plans § 3931.100 Boundary pillars and buffer zones... prior written consent or on the BLM's order. For in-situ operations, a 50-foot buffer zone from...

  16. Buffer for a gamma-insensitive optical sensor with gas and a buffer assembly

    DOEpatents

    Kruger, H.W.

    1994-05-10

    A buffer assembly is disclosed for a gamma-insensitive gas avalanche focal plane array operating in the ultra-violet/visible/infrared energy wavelengths and using a photocathode and an avalanche gas located in a gap between an anode and the photocathode. The buffer assembly functions to eliminate chemical compatibility between the gas composition and the materials of the photocathode. The buffer assembly in the described embodiment is composed of two sections, a first section constructed of glass honeycomb under vacuum and a second section defining a thin barrier film or membrane constructed, for example, of Al and Be, which is attached to and supported by the honeycomb. The honeycomb section, in turn, is supported by and adjacent to the photocathode. 7 figures.

  17. Buffer for a gamma-insensitive optical sensor with gas and a buffer assembly

    DOEpatents

    Kruger, Hans W.

    1994-01-01

    A buffer assembly for a gamma-insensitive gas avalanche focal plane array operating in the ultra-violet/visible/infrared energy wavelengths and using a photocathode and an avalanche gas located in a gap between an anode and the photocathode. The buffer assembly functions to eliminate chemical compatibility between the gas composition and the materials of the photocathode. The buffer assembly in the described embodiment is composed of two sections, a first section constructed of glass honeycomb under vacuum and a second section defining a thin barrier film or membrane constructed, for example, of Al and Be, which is attached to and supported by the honeycomb. The honeycomb section, in turn, is supported by and adjacent to the photocathode.

  18. Hybrid Silicon AWG Lasers and Buffers

    NASA Astrophysics Data System (ADS)

    Kurczveil, Geza

    Silicon photonics promises the low cost integration of optical components with CMOS electronics thus enabling optical interconnects in future generation processors. The hybrid silicon platform (HSP) is one approach to make optically active components on silicon. While many optical components on the HSP have been demonstrated, few photonic integrated circuits (PICs), consisting of multiple elements, have been demonstrated. In this dissertation, two Hybrid Silicon PICs and their building blocks will be presented. The first PIC to be presented is a multiwavelength laser based on an AWG. It consists of Fabry-Perot cavities integrated with hybrid silicon amplifiers and an intracavity filter in the form of an AWG with a channel spacing of 360 GHz. Four-channel lasing operation is shown. Single-sided fiber-coupled output powers as high as 35 µW are measured. The SMSR is as high as 35 dB. Various device characteristics are compromised as the AWG was attacked during the III-V process, thus showing the need to properly protect passive components during III-V processing. The second PIC to be presented is a fully integrated optical buffer. The device consists of a hybrid silicon switch, a 1.1 m long silicon waveguide, and cascaded hybrid silicon amplifiers. The passive delay line is protected by dielectric layers to limit passive losses to 0.5 dB/cm. Noise filters in the form of saturable absorbers are integrated in the buffer to allow for a larger number of recirculations in the delay line compared to a delay without filters. Tapers are used to transition the mode from the passive region to the hybrid region with losses as low as 0.22 dB per transition and reflectivities below -35 dB. Error free operation of the hybrid silicon switch is demonstrated in all four paths. The integrated buffer failed due to low yield, showing the current limitations of the HSP.

  19. Analysis of a hybrid, unidirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1983-01-01

    A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. As an example, for a damaged graphite/epoxy laminate, the results demonstrate the manner in which to select the most efficient combination of buffer strip properties necessary to inhibit crack growth. Ultimate failure of the laminate after crack arrest can occur under increasing load either by continued crack extension through the buffer strips or the crack can jump the buffer strips. For some typical hybrid materials it is found that a buffer strip spacing-to-width ratio of about four to one is the most efficient.

  20. Analysis of a hybrid-undirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1983-01-01

    A method of analysis capable of predicting accurately the fracture behavior of a unidirectional composite laminate containing symmetrically placed buffer strips is presented. As an example, for a damaged graphite/epoxy laminate, the results demonstrate the manner in which to select the most efficient combination of buffer strip properties necessary to inhibit crack growth. Ultimate failure of the laminate after the arrest can occur under increasing load either by continued crack extension through the buffer strips or the crack can jump the buffer strips. For some typical hybrid materials it is found that a buffer strip spacing to width ratio of about four to one is the most efficient.

  1. Concentrated Flow through a Riparian Buffer: A Case Study

    NASA Astrophysics Data System (ADS)

    Young, C. B.; Nogues, J. P.; Hutchinson, S. L.

    2005-05-01

    Riparian buffers are often used for in-situ treatment of agricultural runoff. Although the benefits of riparian buffers are well recongized, concentration of flow can restrict the efficiency of contaminant removal. This study evaluates flow concentration at a agricultural site near Manhattan, Kansas. Manual and automated GIS analyses of a high-resolution digital elevation model were used to determine the fraction of runoff contributing to each buffer segment. Subsequent simulation of the system in WEPP (Water Erosion and Prediction Project) demonstrates the extent to which flow concentration affects buffer efficiency. Recommendations are presented for the design of adaptive-width buffers.

  2. k(+)-buffer: An Efficient, Memory-Friendly and Dynamic k-buffer Framework.

    PubMed

    Vasilakis, Andreas-Alexandros; Papaioannou, Georgios; Fudos, Ioannis

    2015-06-01

    Depth-sorted fragment determination is fundamental for a host of image-based techniques which simulates complex rendering effects. It is also a challenging task in terms of time and space required when rasterizing scenes with high depth complexity. When low graphics memory requirements are of utmost importance, k-buffer can objectively be considered as the most preferred framework which advantageously ensures the correct depth order on a subset of all generated fragments. Although various alternatives have been introduced to partially or completely alleviate the noticeable quality artifacts produced by the initial k-buffer algorithm in the expense of memory increase or performance downgrade, appropriate tools to automatically and dynamically compute the most suitable value of k are still missing. To this end, we introduce k(+)-buffer, a fast framework that accurately simulates the behavior of k-buffer in a single rendering pass. Two memory-bounded data structures: (i) the max-array and (ii) the max-heap are developed on the GPU to concurrently maintain the k-foremost fragments per pixel by exploring pixel synchronization and fragment culling. Memory-friendly strategies are further introduced to dynamically (a) lessen the wasteful memory allocation of individual pixels with low depth complexity frequencies, (b) minimize the allocated size of k-buffer according to different application goals and hardware limitations via a straightforward depth histogram analysis and (c) manage local GPU cache with a fixed-memory depth-sorting mechanism. Finally, an extensive experimental evaluation is provided demonstrating the advantages of our work over all prior k-buffer variants in terms of memory usage, performance cost and image quality. PMID:26357252

  3. Branch target buffer design and optimization

    NASA Technical Reports Server (NTRS)

    Perleberg, Chris H.; Smith, Alan J.

    1993-01-01

    Consideration is given to two major issues in the design of branch target buffers (BTBs), with the goal of achieving maximum performance for a given number of bits allocated to the BTB design. The first issue is BTB management; the second is what information to keep in the BTB. A number of solutions to these problems are reviewed, and various optimizations in the design of BTBs are discussed. Design target miss ratios for BTBs are developed, making it possible to estimate the performance of BTBs for real workloads.

  4. Spacecraft optical disk recorder memory buffer control

    NASA Technical Reports Server (NTRS)

    Hodson, Robert F.

    1992-01-01

    The goal of this project is to develop an Application Specific Integrated Circuit (ASIC) for use in the control electronics of the Spacecraft Optical Disk Recorder (SODR). Specifically, this project is to design an extendable memory buffer controller ASIC for rate matching between a system Input/Output port and the SODR's device interface. The aforementioned goal can be partitioned into the following sub-goals: (1) completion of ASIC design and simulation (on-going via ASEE fellowship); (2) ASIC Fabrication (at ASIC manufacturer); and (3) ASIC Testing (NASA/LaRC, Christopher Newport University).

  5. Buffer layers and articles for electronic devices

    DOEpatents

    Paranthaman, Mariappan P.; Aytug, Tolga; Christen, David K.; Feenstra, Roeland; Goyal, Amit

    2004-07-20

    Materials for depositing buffer layers on biaxially textured and untextured metallic and metal oxide substrates for use in the manufacture of superconducting and other electronic articles comprise RMnO.sub.3, R.sub.1-x A.sub.x MnO.sub.3, and combinations thereof; wherein R includes an element selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and A includes an element selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Ra.

  6. Oxidative phosphorylation and energy buffering in cyanobacteria.

    PubMed Central

    Nitschmann, W H; Peschek, G A

    1986-01-01

    The onset of respiration in the cyanobacteria Anacystis nidulans and Nostoc sp. strain Mac upon a shift from dark anaerobic to aerobic conditions was accompanied by rapid energization of the adenylate pool (owing to the combined action of ATP synthase and adenylate kinase) and also the guanylate, uridylate, and cytidylate pools (owing to nucleoside diphosphate and nucleoside monophosphate kinases). Rates of the various transphosphorylation reactions were comparable to the rate of oxidative phosphorylation, thus explaining, in part, low approximately P/O ratios which incorporate adenylates only. The increase of ATP, GTP, UTP, and CTP levels (nanomoles per minute per milligram [dry weight]) in oxygen-pulsed cells of A. nidulans and Nostoc species was calculated to be, on average, 2.3, 1.05, 0.8, and 0.57, respectively. Together with aerobic steady-state pool sizes of 1.35, 0.57, 0.5, and 0.4 nmol/mg (dry weight) for these nucleotides, a fairly uniform turnover of 1.3 to 1.5 min-1 was derived. All types of nucleotides, therefore, may be conceived of as being in equilibrium with each other, reflecting the energetic homeostasis or energy buffering of the (respiring) cyanobacterial cell. For the calculation of net efficiencies of oxidative phosphorylation in terms of approximately P/O ratios, this energy buffering was taken into account. Moreover, in A. nidulans an additional 30% of the energy initially conserved in ATP by oxidative phosphorylation was immediately used up by a plasma membrane-bound reversible H+-ATPase for H+ extrusion. Consequently, by allowing for energy buffering and ATPase-linked H+ extrusion, maximum P/O ratios of 2.6 to 3.3 were calculated. By contrast, in Nostoc sp. all the H+ extrusion, appeared to be linked to a plasma membrane-bound respiratory chain, thus bypassing any ATP formation and leading to P/O ratios of only 1.3 to 1.5 despite the correction for energy buffering. PMID:3023299

  7. Performance improvement of polymer solar cells by using a solution processible titanium chelate as cathode buffer layer

    NASA Astrophysics Data System (ADS)

    Tan, Zhan'ao; Yang, Chunhe; Zhou, Erjun; Wang, Xiang; Li, Yongfang

    2007-07-01

    A solution processible titanium chelate, titanium (diisopropoxide) bis (2,4-pentanedionate) (TIPD), was used as the cathode buffer layer in the polymer solar cells (PSCs) based on the blend of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] and [6,6]-phenyl-C61-butyric acid methyl ester. Introducing TIPD buffer layer reduced the interface resistance between the active layer and Al electrode, leading to a lower device resistance. The power conversion efficiency of the PSC with TIPD buffer layer reached 2.52% under the illumination of AM1.5, 100mW/cm2, which is increased by 51.8% in comparison with that (1.66%) of the device without TIPD buffer layer under the same experimental conditions.

  8. In vitro dissolution of proton-pump inhibitor products intended for paediatric and geriatric use in physiological bicarbonate buffer.

    PubMed

    Liu, Fang; Shokrollahi, Honaz

    2015-05-15

    Proton-pump inhibitor (PPI) products based on enteric coated multiparticulates are design to meet the needs of patients who cannot swallow tablets such as children and older adults. Enteric coated PPI preparations exhibit delays in in vivo absorption and onset of antisecretory effects, which is not reflected by the rapid in vitro dissolution in compendial pH 6.8 phosphate buffer commonly used for assessment of these products. A more representative and physiological medium, pH 6.8 mHanks bicarbonate buffer, was used in this study to evaluate the in vitro dissolution of enteric coated multiparticulate-based PPI products. Commercially available omeprazole, lansoprazole and esomeprazole products were subject to dissolution tests using USP-II apparatus in pH 4.5 phosphate buffer saline for 45 min (acid stage) followed by pH 6.8 phosphate buffer or pH 6.8 mHanks bicarbonate buffer. In pH 6.8 phosphate buffer, all nine tested products displayed rapid and comparable dissolution profiles meeting the pharmacopeia requirements for delayed release preparations. In pH 6.8 mHanks buffer, drug release was delayed and failed the pharmacopeia requirements from most enteric coated preparations. Despite that the same enteric polymer, methacrylic acid-ethyl acrylate copolymer (1:1), was applied to all commercial multiparticulate-based products, marked differences were observed between dissolution profiles of these preparations. The use of pH 6.8 physiological bicarbonate (mHanks) buffer can serve as a useful tool to provide realistic and discriminative in vitro release assessment of enteric coated PPI preparations and to assist rational formulation development of these products. PMID:25746736

  9. Buffer allocation in an ATM switch with output buffer and speed constraints

    NASA Astrophysics Data System (ADS)

    Gupta, Anil K.; Georganas, N. D.

    A synchronous nonblocking N times N switch for asynchronous transfer mode (ATM) networks or high speed packet switching networks transporting fixed length packets called cells is considered. Such a switch with output queuing achieves the optimal performance, however it requires the switch fabric to work at the speed of N. In practice the switch may operate L times faster than the input/output trunk. It is assumed that queues at each output port have a limited buffer space and whenever an output queue is full, the back-pressure is applied and the packets are retained at the head of the input queues. The upper bound on the packet loss probability at the input queues in such a switch are computed. To achieve a given packet loss rate, the switch with L equals 2 requires almost the same amount of input and output buffers as with L equals 4 up to 70 percent input load, but as the load increases beyond 70 percent the switch with L equals 4 would require more output buffers and less input buffers in comparison with a switch operating at L equals 2. The performance of a switch with L equals 3 is very similar to that for L equals 4 and is not considered.

  10. Corrosion in low dielectric constant Si-O based thin films: Buffer concentration effects

    SciTech Connect

    Zeng, F. W.; Lane, M. W.; Gates, S. M.

    2014-05-15

    Organosilicate glass (OSG) is often used as an interlayer dielectric (ILD) in high performance integrated circuits. OSG is a brittle material and prone to stress-corrosion cracking reminiscent of that observed in bulk glasses. Of particular concern are chemical-mechanical planarization techniques and wet cleans involving solvents commonly encountered in microelectronics fabrication where the organosilicate film is exposed to aqueous environments. Previous work has focused on the effect of pH, surfactant, and peroxide concentration on the subcritical crack growth of these films. However, little or no attention has focused on the effect of the conjugate acid/base concentration in a buffer. Accordingly, this work examines the “strength” of the buffer solution in both acidic and basic environments. The concentration of the buffer components is varied keeping the ratio of acid/base and therefore pH constant. In addition, the pH was varied by altering the acid/base ratio to ascertain any additional effect of pH. Corrosion tests were conducted with double-cantilever beam fracture mechanics specimens and fracture paths were verified with ATR-FTIR. Shifts in the threshold fracture energy, the lowest energy required for bond rupture in the given environment, G{sub TH}, were found to shift to lower values as the concentration of the base in the buffer increased. This effect was found to be much larger than the effect of the hydroxide ion concentration in unbuffered solutions. The results are rationalized in terms of the salient chemical bond breaking process occurring at the crack tip and modeled in terms of the chemical potential of the reactive species.

  11. Damage tolerance of woven graphite-epoxy buffer strip panels

    NASA Technical Reports Server (NTRS)

    Kennedy, John M.

    1990-01-01

    Graphite-epoxy panels with S glass buffer strips were tested in tension and shear to measure their residual strengths with crack-like damage. The buffer strips were regularly spaced narrow strips of continuous S glass. Panels were made with a uniweave graphite cloth where the S glass buffer material was woven directly into the cloth. Panels were made with different width and thickness buffer strips. The panels were loaded to failure while remote strain, strain at the end of the slit, and crack opening displacement were monitoring. The notched region and nearby buffer strips were radiographed periodically to reveal crack growth and damage. Except for panels with short slits, the buffer strips arrested the propagating crack. The strength (or failing strain) of the panels was significantly higher than the strength of all-graphite panels with the same length slit. Panels with wide, thick buffer strips were stronger than panels with thin, narrow buffer strips. A shear-lag model predicted the failing strength of tension panels with wide buffer strips accurately, but over-estimated the strength of the shear panels and the tension panels with narrow buffer strips.

  12. Lack of Buffering by Composites Promotes Shift to More Cariogenic Bacteria.

    PubMed

    Nedeljkovic, I; De Munck, J; Slomka, V; Van Meerbeek, B; Teughels, W; Van Landuyt, K L

    2016-07-01

    Secondary caries (SC) remains a very important problem with composite restorations. The objectives of this study were to test the acid-buffering ability of several restorative materials and to evaluate whether buffering of the restorative material has an impact on the microbial composition of the biofilm. Disk-shaped specimens of conventional composite, composite with surface prereacted glass-ionomer filler particles (so-called giomer), glass-ionomer cement (GIC), amalgam, and hydroxyapatite (HAp) (control) were exposed to aqueous solutions with pH 4, 5, 6, and 7 and to the medium containing bacteria-produced acids, and pH changes were recorded over several days. Next, material specimens were immersed in bacterial growth medium with pH adjusted to 5. After a 24-h incubation, the extracts were collected and inoculated with a cariogenic (Streptococcus mutans) and a noncariogenic (Streptococcus sanguinis) species. The bacterial growth was monitored both in a single-species model by spectrophotometry and in a dual-species model by viability quantitative polymerase chain reaction. Amalgam and HAp showed the strongest acid-buffering ability, followed by the GIC and the giomer, while the conventional composite did not exhibit any buffering capacity. Furthermore, due to the lack of acid-buffering abilities, composite was not able to increase the pH of the medium (pH 5), which, in the absence of antibacterial properties, allowed the growth of S. mutans, while the growth of S. sanguinis, a less aciduric species, was completely inhibited. A similar effect was observed when bacteria were cultured together: there was a higher percentage of S. mutans and lower percentage of S. sanguinis with the conventional composite than with other materials and HAp. In conclusion, conventional composites lack the ability to increase the local pH, which leads to the outgrowth of more acidogenic/aciduric bacteria and higher cariogenicity of the biofilm. Together with lack of antibacterial

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

    SciTech Connect

    Sundaramurthi, Prakash; Shalaev, Evgenyi; Suryanarayanan, Raj

    2010-06-22

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

  14. Surface Treatments of Nb by Buffered Electropolishing

    SciTech Connect

    Wu, Andy T.; Rimmer, Robert A.; Ciovati, Gianluigi; Manus, Robert L.; Reece, Charles E.; Williams, J. S.; Eozénou, F.; Jin, S.; Wang, E.

    2009-11-01

    Buffered electropolishing (BEP) is a Nb surface treatment technique developed at Jefferson Lab1. Experimental results obtained from flat Nb samples show2-4 that BEP can produce a surface finish much smoother than that produced by the conventional electropolishing (EP), while Nb removal rate can be as high as 4.67 μm/min. This new technique has been applied to the treatments of Nb SRF single cell cavity employing a vertical polishing system5 constructed at JLab as well as a horizontal polishing system at CEA Saclay. Preliminary results show that the accelerating gradient can reach 32 MV/m for a large grain cavity and 26.7 MV/m for a regular grain cavity. In this presentation, the latest progresses from the international collaboration between Peking University, CEA Saclay, and JLab on BEP will be summarized.

  15. Microscopic optical buffering in a harmonic potential

    NASA Astrophysics Data System (ADS)

    Sumetsky, M.

    2015-12-01

    In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices.

  16. Microscopic optical buffering in a harmonic potential

    PubMed Central

    Sumetsky, M.

    2015-01-01

    In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices. PMID:26689546

  17. Aerosol buffering of marine boundary layer cloudiness

    NASA Astrophysics Data System (ADS)

    Kazil, J.; Feingold, G.; Wang, H.

    2010-12-01

    The role of aerosol particles in maintaining a cloudy boundary layer in the remote marine environment is explored. It has previously been shown that precipitation can result in the transition from a closed- to open-cellular state but that the boundary layer cannot maintain this open-cell state without a resupply of particles. Potential sources include wind-driven production of sea salt particles from the ocean, nucleation from the gas phase, and entrainment from the free troposphere. Here we investigate with model simulations how the interplay of cloud properties, aerosol production, and boundary layer dynamics results in aerosol sources acting as a buffer against processes that destabilize cloudiness and the dynamic state of the marine boundary layer. For example, at nighttime, cloud liquid water increases in the absence of solar heating, resulting in increased precipitation, stronger cloud top cooling, accelerated boundary layer turbulence, and faster surface wind speeds. Faster surface wind speeds drive an enhanced flux of sea salt aerosol, at a time when aerosol particles are scavenged more readily by enhanced precipitation. In contrast, absorption of solar radiation during daytime reduces cloud water, decelerates boundary layer turbulence, reduces surface wind speeds, and therefore slows surface emissions. This is compensated by nucleation of small aerosol particles from the gas phase in response to the nigh complete removal of cloud condensation nuclei in precipitating open cell walls. These newly formed particles need to grow to larger sizes before they can serve as cloud condensation nuclei (CCN), but will likely contribute to the CCN population during the nighttime and, together with ocean emissions, buffer the system against precipitation removal.

  18. Cost of riparian buffer zones: A comparison of hydrologically adapted site-specific riparian buffers with traditional fixed widths

    NASA Astrophysics Data System (ADS)

    Tiwari, T.; Lundström, J.; Kuglerová, L.; Laudon, H.; Öhman, K.; Ågren, A. M.

    2016-02-01

    Traditional approaches aiming at protecting surface waters from the negative impacts of forestry often focus on retaining fixed width buffer zones around waterways. While this method is relatively simple to design and implement, it has been criticized for ignoring the spatial heterogeneity of biogeochemical processes and biodiversity in the riparian zone. Alternatively, a variable width buffer zone adapted to site-specific hydrological conditions has been suggested to improve the protection of biogeochemical and ecological functions of the riparian zone. However, little is known about the monetary value of maintaining hydrologically adapted buffer zones compared to the traditionally used fixed width ones. In this study, we created a hydrologically adapted buffer zone by identifying wet areas and groundwater discharge hotspots in the riparian zone. The opportunity cost of the hydrologically adapted riparian buffer zones was then compared to that of the fixed width zones in a meso-scale boreal catchment to determine the most economical option of designing riparian buffers. The results show that hydrologically adapted buffer zones were cheaper per hectare than the fixed width ones when comparing the total cost. This was because the hydrologically adapted buffers included more wetlands and low productive forest areas than the fixed widths. As such, the hydrologically adapted buffer zones allows more effective protection of the parts of the riparian zones that are ecologically and biogeochemically important and more sensitive to disturbances without forest landowners incurring any additional cost than fixed width buffers.

  19. Buffer strip design for protecting water quality and fish habitat

    SciTech Connect

    Belt, G.H.; O'Laughlin, J. )

    1994-04-01

    Buffer strips are protective areas adjacent to streams or lakes. Among other functions, they protect water quality and fish habitat. A typical buffer strip is found in western Oregon, where they are called Riparian Management Areas (RMAs). The authors use the term buffer strip to include functional descriptions such as filter, stabilization, or leave strips, and administrative designations such as Idaho's Stream Protection Zone (SPZ), Washington's Riparian Management Zone (RMZ), and the USDA Forest Service's Streamside Management Zone (SMZ). They address water quality and fishery protective functions of buffer strips on forestlands, pointing out improvements in buffer strip design possible through research or administrative changes. Buffer strip design requirements found in some western Forest Practices Act (FPA) regulations are also compared and related to findings in the scientific literature.

  20. The Multimission Image Processing Laboratory's virtual frame buffer interface

    NASA Technical Reports Server (NTRS)

    Wolfe, T.

    1984-01-01

    Large image processing systems use multiple frame buffers with differing architectures and vendor supplied interfaces. This variety of architectures and interfaces creates software development, maintenance and portability problems for application programs. Several machine-dependent graphics standards such as ANSI Core and GKS are available, but none of them are adequate for image processing. Therefore, the Multimission Image Processing laboratory project has implemented a programmer level virtual frame buffer interface. This interface makes all frame buffers appear as a generic frame buffer with a specified set of characteristics. This document defines the virtual frame uffer interface and provides information such as FORTRAN subroutine definitions, frame buffer characteristics, sample programs, etc. It is intended to be used by application programmers and system programmers who are adding new frame buffers to a system.

  1. Optimization of buffer injection for the effective bioremediation of chlorinated solvents in aquifers

    NASA Astrophysics Data System (ADS)

    Brovelli, A.; Robinson, C.; Barry, A.; Kouznetsova, I.; Gerhard, J.

    2008-12-01

    Various techniques have been proposed to enhance biologically-mediated reductive dechlorination of chlorinated solvents in the subsurface, including the addition of fermentable organic substrate for the generation of H2 as an electron donor. One rate-limiting factor for enhanced dechlorination is the pore fluid pH. Organic acids and H+ ions accumulate in dechlorination zones, generating unfavorable conditions for microbial activity (pH < 6.5). The pH variation is a nonlinear function of the amount of reduced chlorinated solvents, and is affected by the organic material fermented, the chemical composition of the pore fluid and the soil's buffering capacity. Consequently, in some cases enhanced remediation schemes rely on buffer injection (e.g., bicarbonate) to alleviate this problem, particularly in the presence of solvent nonaqueous phase liquid (NAPL) source zones. However, the amount of buffer required - particularly in complex, evolving biogeochemical environments - is not well understood. To investigate this question, this work builds upon a geochemical numerical model (Robinson et al., Science of the Total Environment, submitted), which computes the amount of additional buffer required to maintain the pH at a level suitable for bacterial activity for batch systems. The batch model was coupled to a groundwater flow/solute transport/chemical reaction simulator to permit buffer optimization computations within the context of flowing systems exhibiting heterogeneous hydraulic, physical and chemical properties. A suite of simulations was conducted in which buffer optimization was examined within the bounds of the minimum concentration necessary to sustain a pH favorable to microbial activity and the maximum concentration to avoid excessively high pH values (also not suitable to bacterial activity) and mineral precipitation (e.g., calcite, which may lead to pore-clogging). These simulations include an examination of the sensitivity of this buffer concentration range

  2. Optimizing buffering chemistry to maintain near neutral pH of broiler feed during pre-enrichment for Salmonella.

    PubMed

    Berrang, M E; Cosby, D E; Cox, N A; Cason, J A; Richardson, K E

    2015-12-01

    Salmonella is a human pathogen that can accompany live broilers to the slaughter plant, contaminating fully processed carcasses. Feed is one potential source of Salmonella to growing broilers. Monitoring feed for the presence of Salmonella is part of good agricultural practice. The first step in culturing feed for Salmonella (which may be at low numbers and sub-lethally stressed) is to add it to a pre-enrichment broth which is incubated for 24 h. During the course of pre-enrichment, extraneous bacteria metabolize carbohydrates in some feed and excrete acidic byproducts, causing the pH to drop dramatically. An acidic pre-enrichment pH can injure or kill Salmonella resulting in a failure to detect, even if it is present and available to infect chickens. The objective of this study was to test an array of buffering chemistries to prevent formation of an injurious acidic environment during pre-enrichment of feed in peptone water. Five grams of feed were added to 45 mL of peptone water buffered with carbonate, Tris pH 8, and phosphate buffering ingredients individually and in combination. Feed was subjected to a pre-enrichment at 35°C for 24 h; pH was measured at 0, 18, and 24 h. Standard phosphate buffering ingredients at concentrations up to 4 times the normal formulation were unable to fully prevent acidic conditions. Likewise, carbonate and Tris pH 8 were not fully effective. The combination of phosphate, carbonate, and Tris pH 8 was the most effective buffer tested. It is recommended that a highly buffered pre-enrichment broth be used to examine feed for the presence of Salmonella. PMID:26467004

  3. The potential effects of pH and buffering capacity on dental erosion.

    PubMed

    Owens, Barry M

    2007-01-01

    Soft drink pH (initial pH) has been shown to be a causative factor--but not necessarily the primary initiating factor--of dental erosion. The titratable acidity or buffering capacity has been acknowledged as playing a significant role in the etiology of these lesions. This in vitro study sought to evaluate five different soft drinks (Coca-Cola Classic, Diet Coke, Gatorade sports drink, Red Bull high-energy drink, Starbucks Frappucino coffee drink) and tap water (control) in terms of initial pH and buffering capacity. Initial pH was measured in triplicate for the six beverages. The buffering capacity of each beverage was assessed by measuring the weight (in grams) of 0.10 M sodium hydroxide necessary for titration to pH levels of 5.0, 6.0, 7.0, and 8.3. Coca-Cola Classic produced the lowest mean pH, while Starbucks Frappucino produced the highest pH of any of the drinks except for tap water. Based on statistical analysis using ANOVA and Fisher's post hoc tests at a P < 0.05 level of significance, Red Bull had the highest mean buffering capacity (indicating the strongest potential for erosion of enamel), followed by Gatorade, Coca-Cola Classic, Diet Coke, and Starbucks Frappucino. PMID:18050578

  4. Stability of ribosomes of Staphylococcus aureus S6 sublethally heated in different buffers.

    PubMed

    Hurst, A; Hughes, A

    1978-02-01

    Cells of Staphylococcus aureus heated at 52 degrees C in magnesium-chelating buffers [pH 7.2, 50 mM potassium phosphate or 50 mM tris(hydroxymethyl)-aminomethane containing 1 mM ethylenediaminetetraacetic acid] leaked 260-nm absorbing material, shown to be RNA, and suffered destruction of their ribosomes. These cells did not regain their salt tolerance when repair was carried out in the presence of actinomycin D (5 microgram/ml). Cells similarly heated in magnesium-conserving buffers [pH 7.2, 50 mM tris(hydroxymethyl)aminomethane containing 10 mM MgCl2 or piperazine buffer] did not leak RNA, suffered no ribosomal damage when heated for 15 min, and recovered, at least partially, in the presence of actinomycin D. Ribosomal damage, is therefore, a consequence of Mg2+ loss and is not an effect of heat per se. Cells suspended in either Mg2+-chelating or Mg2+-conserving buffers lost salt tolerance to about the same extent during heating at 52 degrees C. Therefore, sublethal heat injury can not be attributed to ribosomal damage. PMID:627531

  5. Grass buffers for playas in agricultural landscapes: A literature synthesis

    USGS Publications Warehouse

    Melcher, Cynthia P.; Skagen, Susan K.

    2005-01-01

    Future research should entail multiple-scale approaches at regional, wetland-complex, and individual watershed scales. Information needs include direct measures of buffer effectiveness in ‘real-world’ systems, refinement and field tests of buffer-effectiveness models, how buffers may affect floral and faunal communities of playas, and basic ecological information on playa function and playa wildlife ecology. Understanding how wildlife communities respond to patch size and habitat fragmentation is crucial for addressing questions regarding habitat quality of grass buffers in playa systems.

  6. An assessment of buffer strips for improving damage tolerance

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.; Kennedy, J. M.

    1981-01-01

    Graphite/epoxy panels with buffer strips were tested in tension to measure their residual strength with crack-like damage. Panels were made with 45/0/-45/90(2S) and 45/0/450(2S) layups. The buffer strips were parallel to the loading directions. They were made by replacing narrow strips of the 0 deg graphite plies with strips of either 0 deg S-Glass/epoxy or Kevlar-49/epoxy on either a one for one or a two for one basis. In a third case, O deg graphite/epoxy was used as the buffer material and thin, perforated Mylar strips were placed between the 0 deg piles and the cross-plies to weaken the interfaces and thus to isolate the 0 deg plies. Some panels were made with buffer strips of different widths and spacings. The buffer strips arrested the cracks and increased the residual strengths significantly over those plain laminates without buffer strips. A shear-lag type stress analysis correctly predicted the effects of layups, buffer material, buffer strip width and spacing, and the number of plies of buffer material.

  7. Tris buffer modulates polydopamine growth, aggregation, and paramagnetic properties.

    PubMed

    Della Vecchia, Nicola Fyodor; Luchini, Alessandra; Napolitano, Alessandra; D'Errico, Gerardino; Vitiello, Giuseppe; Szekely, Noemi; d'Ischia, Marco; Paduano, Luigi

    2014-08-19

    Despite the growing technological interest of polydopamine (dopamine melanin)-based coatings for a broad variety of applications, the factors governing particle size, shape, and electronic properties of this bioinspired multifunctional material have remained little understood. Herein, we report a detailed characterization of polydopamine growth, particle morphology, and paramagnetic properties as a function of dopamine concentration and nature of the buffer (pH 8.5). Dynamic Light Scattering data revealed an increase in the hydrodynamic radii (Rh) of melanin particles with increasing dopamine concentration in all buffers examined, especially in phosphate buffer. Conversely, a marked inhibition of particle growth was apparent in Tris buffer, with Rh remaining as low as <100 nm during polymerization of 0.5 mM dopamine. Small angle neutron scattering data suggested formation of bidimensional structures in phosphate or bicarbonate buffers, while apparently three-dimensional fractal objects prevailed in Tris buffer. Finally, electron paramagnetic resonance spectra revealed a broader signal amplitude with a peculiar power saturation decay profile for polydopamine samples prepared in Tris buffer, denoting more homogeneous paramagnetic centers with respect to similar samples obtained in phosphate and bicarbonate buffers. Overall, these results disclose Tris buffer as an efficient modulator of polydopamine buildup and properties for the rational control and fine-tuning of melanin aggregate size, morphology, and free radical behavior. PMID:25066905

  8. Concentrated Flow through a Riparian Buffer: A Case Study

    NASA Astrophysics Data System (ADS)

    Young, C. B.; Nogues, J. P.; Hutchinson, S. L.

    2004-05-01

    Riparian buffers are often used for in-situ treatment of agricultural runoff. Although the benefits of riparian buffers are well recongized, concentration of flow can restrict the efficiency of contaminant removal. This study evaluates flow concentration at a agricultural site near Manhattan, Kansas. Manual and automated GIS analyses of a high-resolution digital elevation model were used to determine the fraction of runoff contributing to each buffer segment. Subsequent simulation of the system in WEPP (Water Erosion and Prediction Project) demonstrates the extend to which flow concentration affects buffer efficiency.

  9. Back contact buffer layer for thin-film solar cells

    DOEpatents

    Compaan, Alvin D.; Plotnikov, Victor V.

    2014-09-09

    A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.

  10. Relationships Between Nitrogen Transformation Rates and Gene Abundance in a Riparian Buffer Soil

    NASA Astrophysics Data System (ADS)

    Wu, Lin; Osmond, Deanna L.; Graves, Alexandria K.; Burchell, Michael R.; Duckworth, Owen W.

    2012-11-01

    Denitrification is a critical biogeochemical process that results in the conversion of nitrate to volatile products, and thus is a major route of nitrogen loss from terrestrial environments. Riparian buffers are an important management tool that is widely utilized to protect water from non-point source pollution. However, riparian buffers vary in their nitrate removal effectiveness, and thus there is a need for mechanistic studies to explore nitrate dynamics in buffer soils. The objectives of this study were to examine the influence of specific types of soluble organic matter on nitrate loss and nitrous oxide production rates, and to elucidate the relationships between these rates and the abundances of functional genes in a riparian buffer soil. Continuous-flow soil column experiments were performed to investigate the effect of three types of soluble organic matter (citric acid, alginic acid, and Suwannee River dissolved organic carbon) on rates of nitrate loss and nitrous oxide production. We found that nitrate loss rates increased as citric acid concentrations increased; however, rates of nitrate loss were weakly affected or not affected by the addition of the other types of organic matter. In all experiments, rates of nitrous oxide production mirrored nitrate loss rates. In addition, quantitative polymerase chain reaction (qPCR) was utilized to quantify the number of genes known to encode enzymes that catalyze nitrite reduction (i.e., nirS and nirK) in soil that was collected at the conclusion of column experiments. Nitrate loss and nitrous oxide production rates trended with copy numbers of both nir and 16s rDNA genes. The results suggest that low-molecular mass organic species are more effective at promoting nitrogen transformations than large biopolymers or humic substances, and also help to link genetic potential to chemical reactivity.

  11. Relationships between nitrogen transformation rates and gene abundance in a riparian buffer soil.

    PubMed

    Wu, Lin; Osmond, Deanna L; Graves, Alexandria K; Burchell, Michael R; Duckworth, Owen W

    2012-11-01

    Denitrification is a critical biogeochemical process that results in the conversion of nitrate to volatile products, and thus is a major route of nitrogen loss from terrestrial environments. Riparian buffers are an important management tool that is widely utilized to protect water from non-point source pollution. However, riparian buffers vary in their nitrate removal effectiveness, and thus there is a need for mechanistic studies to explore nitrate dynamics in buffer soils. The objectives of this study were to examine the influence of specific types of soluble organic matter on nitrate loss and nitrous oxide production rates, and to elucidate the relationships between these rates and the abundances of functional genes in a riparian buffer soil. Continuous-flow soil column experiments were performed to investigate the effect of three types of soluble organic matter (citric acid, alginic acid, and Suwannee River dissolved organic carbon) on rates of nitrate loss and nitrous oxide production. We found that nitrate loss rates increased as citric acid concentrations increased; however, rates of nitrate loss were weakly affected or not affected by the addition of the other types of organic matter. In all experiments, rates of nitrous oxide production mirrored nitrate loss rates. In addition, quantitative polymerase chain reaction (qPCR) was utilized to quantify the number of genes known to encode enzymes that catalyze nitrite reduction (i.e., nirS and nirK) in soil that was collected at the conclusion of column experiments. Nitrate loss and nitrous oxide production rates trended with copy numbers of both nir and 16s rDNA genes. The results suggest that low-molecular mass organic species are more effective at promoting nitrogen transformations than large biopolymers or humic substances, and also help to link genetic potential to chemical reactivity. PMID:22996400

  12. Performance of various input-buffered and output-buffered ATM switch design principles under bursty traffic: Simulation study

    NASA Astrophysics Data System (ADS)

    Liew, Soung C.

    1994-02-01

    This paper investigates the packet loss probabilities of several alternative input-buffered and output-buffered switch designs with finite amounts of buffer space. The effects of bursty traffic, modeled by geometrically distributed active and idle periods, are explored. Methods for improving switch performance are classified, and their effectiveness for dealing with bursty traffic discussed. This work indicates that bursty traffic can degrade switch performance significantly and that it is difficult to alleviate the performance degradation by merely restricting the offered traffic load. Unless buffers are shared, or very large buffers provided, strategies that improve throughput under uniform random traffic are not very effective under bursty traffic. For input-buffered switches, our investigation suggests that the specific contention resolution scheme we use is a more important performance factor under bursty traffic than it is under uniform random traffic.

  13. Analysis of pH and buffer effects on flucytosine activity in broth dilution susceptibility testing of Candida albicans in two synthetic media.

    PubMed Central

    Calhoun, D L; Galgiani, J N

    1984-01-01

    We examined the influences of different pH levels and three different buffers on flucytosine activity against 12 isolates of Candida albicans in two synthetic media, yeast nitrogen base (YNB) and synthetic amino acid medium-fungal (SAAMF), using broth dilution techniques and measuring the endpoints of visual MICs and turbidimetric 50% inhibitory concentrations. The two media were originally prepared as follows: YNB, unbuffered, pH 5.6; SAAMF, buffered with morpholinepropanesulfonic acid-Tris, pH 7.4; the resultant geometric mean MIC and 50% inhibitory concentration of 5-FC were 78- and 32-fold higher, respectively, in SAAMF. Raising the pH of YNB or lowering the pH of SAAMF had virtually no effect on these differences in MIC and 50% inhibitory concentration in the two media. In contrast, virtually all of the discrepancy appeared to be due to morpholinepropanesulfonic acid-Tris, which exerted concentration-dependent inhibition of flucytosine activity not evident when N-2-hydroxyethylpiperazine-N'-ethanesulfonic acid or phosphate buffer systems were substituted. In other turbidimetric studies, growth was slowed more than 50% in YNB as the pH was raised to 7.4, regardless of which buffer was used. Based on our studies, we recommend modifying the composition of SAAMF by substituting a nonantagonistic buffer if any buffer is to be used with SAAMF in the testing of flucytosine. With this modification, SAAMF warrants further study as a generally applicable medium for fungal-susceptibility testing. PMID:6391370

  14. Salivary pH and Buffering Capacity as Risk Markers for Early Childhood Caries: A Clinical Study

    PubMed Central

    Ganesan, S

    2015-01-01

    ABSTRACT Background: The diagnostic utility of saliva is currently being explored in various branches of dentistry, remarkably in the field of caries research. This study was aimed to determine if assessment of salivary pH and buffering capacity would serve as reliable tools in risk prediction of early childhood caries (ECC). Materials and methods: Paraffin-stimulated salivary samples were collected from 50 children with ECC (group I) and 50 caries free children (group II). Salivary pH and buffering capacity (by titration with 0.1 N hydrochloric acid) were assessed using a handheld digital pH meter in both groups. The data obtained were subjected to statistical analysis. Results: Statistically, no significant difference was observed between both the groups for all salivary parameters assessed, except for the buffering capacity level at 150 μl titration of 0.1 N hydrochloric acid (p = 0.73; significant at 1% level). Conclusion: Salivary pH and buffering capacity may not serve as reliable markers for risk prediction of ECC. How to cite this article: Jayaraj D, Ganesan S. Salivary pH and Buffering Capacity as Risk Markers for Early Childhood Caries: A Clinical Study. Int J Clin Pediatr Dent 2015;8(3):167-171. PMID:26628849

  15. Coupled Ca2+/H+ transport by cytoplasmic buffers regulates local Ca2+ and H+ ion signaling.

    PubMed

    Swietach, Pawel; Youm, Jae-Boum; Saegusa, Noriko; Leem, Chae-Hun; Spitzer, Kenneth W; Vaughan-Jones, Richard D

    2013-05-28

    Ca(2+) signaling regulates cell function. This is subject to modulation by H(+) ions that are universal end-products of metabolism. Due to slow diffusion and common buffers, changes in cytoplasmic [Ca(2+)] ([Ca(2+)]i) or [H(+)] ([H(+)]i) can become compartmentalized, leading potentially to complex spatial Ca(2+)/H(+) coupling. This was studied by fluorescence imaging of cardiac myocytes. An increase in [H(+)]i, produced by superfusion of acetate (salt of membrane-permeant weak acid), evoked a [Ca(2+)]i rise, independent of sarcolemmal Ca(2+) influx or release from mitochondria, sarcoplasmic reticulum, or acidic stores. Photolytic H(+) uncaging from 2-nitrobenzaldehyde also raised [Ca(2+)]i, and the yield was reduced following inhibition of glycolysis or mitochondrial respiration. H(+) uncaging into buffer mixtures in vitro demonstrated that Ca(2+) unloading from proteins, histidyl dipeptides (HDPs; e.g., carnosine), and ATP can underlie the H(+)-evoked [Ca(2+)]i rise. Raising [H(+)]i tonically at one end of a myocyte evoked a local [Ca(2+)]i rise in the acidic microdomain, which did not dissipate. The result is consistent with uphill Ca(2+) transport into the acidic zone via Ca(2+)/H(+) exchange on diffusible HDPs and ATP molecules, energized by the [H(+)]i gradient. Ca(2+) recruitment to a localized acid microdomain was greatly reduced during intracellular Mg(2+) overload or by ATP depletion, maneuvers that reduce the Ca(2+)-carrying capacity of HDPs. Cytoplasmic HDPs and ATP underlie spatial Ca(2+)/H(+) coupling in the cardiac myocyte by providing ion exchange and transport on common buffer sites. Given the abundance of cellular HDPs and ATP, spatial Ca(2+)/H(+) coupling is likely to be of general importance in cell signaling. PMID:23676270

  16. Cadmium resistance screening in nitrilotriacetate-buffered minimal media. [Rhizobium fredii

    SciTech Connect

    Angle, J.S. ); Chaney, R.L. )

    1989-08-01

    Media used to determine the MICs of heavy metals for bacteria are unreliable because organic components in the media bind or chelate most of the metal being studied. To define specific metal activity in media and to maintain metal activity at a constant level, HEPES-MES (N-2-hydroxyethylpiperazine-N{prime}-2-ethanesulfonic acid-2-(N-morpholine)ethanesulfonic acid) salts medium with arabinose medium was modified, and the modified medium was used to examine the MIC of cadmium for Rhizobium fredii USDA 201. Arabinose-HEPES-MES was modified by addition of the chelator nitrilotriacetate to buffer the supply of free Cd{sup 2+} ion to maintain a constant Cd activity and by the use of only MES to buffer pH (buffered arabinose-MES medium (BAM)). Ca and Mg were supplied at the normal levels for soil solutions, and other trace elements were supplied at the levels required for normal growth of plants. The concentration of free Cd{sup 2+} ion was calculated by using the computer program GEOCHEM-PC with a corrected data base. The Cd MIC in BAM was 14.0 {mu}M, while that in a tryptone-yeast extract medium was 107 {mu}M. The results indicate that substantial free Cd{sup 2+} is removed from solution in most standard media, resulting in falsely high MICs. The new BAM medium allows for the precise determination of MICs, thus avoiding the uncertainties associated with other media.

  17. Secular decline of seawater calcium increases seawater buffering and pH

    NASA Astrophysics Data System (ADS)

    Hain, M.; Sigman, D. M.; Higgins, J. A.; Haug, G. H.

    2015-12-01

    Reconstructed changes in seawater calcium and magnesium concentration ([Ca2+], [Mg2+]) predictably affect the ocean's acid/base and carbon chemistry. Yet inaccurate formulations of chemical equilibrium "constants" are currently in use to account for these changes. Here we develop an efficient implementation of the MIAMI Ionic Interaction Model (Millero and Pierrot, 1998) to predict all chemical equilibrium constants required for carbon chemistry calculations under variable [Ca2+] and [Mg2+] (Hain et al., 2015). We investigate the impact of [Ca2+] and [Mg2+] on the relationships among the ocean's pH, CO2, dissolved inorganic carbon (DIC), saturation state of CaCO3 (Ω), and buffer capacity. Increasing [Ca2+] and/or [Mg2+] enhances "ion pairing," which increases seawater buffering by increasing the concentration ratio of total to "free" (uncomplexed) carbonate ion. An increase in [Ca2+], however, also causes a decline in carbonate ion to maintain a given Ω, thereby overwhelming the ion pairing effect and decreasing seawater buffering. Given the reconstructions of Eocene [Ca2+] and [Mg2+] ([Ca2+]~20mM; [Mg2+]~30 mM), Eocene seawater would have required essentially the same DIC as today to simultaneously explain a similar-to-modern Ω and the estimated Eocene atmospheric CO2 of ~1000 ppm. During the Cretaceous, at ~4 times modern [Ca2+], ocean buffering would have been at a minimum. Overall, during times of high seawater [Ca2+], CaCO3 saturation, pH, and atmospheric CO2 were more susceptible to perturbations of the global carbon cycle. For example, given both Eocene and Cretaceous seawater [Ca2+] and [Mg2+], a doubling of atmospheric CO2 would require less carbon addition to the ocean/atmosphere system than under modern seawater composition. Moreover, increase in seawater buffering since the Cretaceous may have been a driver of evolution by raising energetic demands of biologically controlled calcification and CO2 concentration mechanisms that aid photosynthesis.

  18. Current isolating epitaxial buffer layers for high voltage photodiode array

    DOEpatents

    Morse, Jeffrey D.; Cooper, Gregory A.

    2002-01-01

    An array of photodiodes in series on a common semi-insulating substrate has a non-conductive buffer layer between the photodiodes and the semi-insulating substrate. The buffer layer reduces current injection leakage between the photodiodes of the array and allows optical energy to be converted to high voltage electrical energy.

  19. Inhibited fragmentation of mAbs in buffered ionic liquids.

    PubMed

    Mazid, Romiza R; Vijayaraghavan, R; MacFarlane, Douglas R; Cortez-Jugo, Christina; Cheng, Wenlong

    2015-05-11

    We thoroughly investigated the biological, structural and chemical stability of epidermal growth factor receptor monoclonal antibody (EGFR mAb) using choline-based buffered ionic liquids (BILs). The results demonstrated substantially enhanced stabilities in our BILs, indicating their huge promise as real-world green biological buffers for antibody storage and transportation. PMID:25869239

  20. Study on the principle and defense of buffer overflow attacks

    NASA Astrophysics Data System (ADS)

    Lin, Wang

    2013-03-01

    Buffer overflow attacks have been the most common form in the network attacks and become a predominant problem in the system and network security area. With specific programs, this paper describes in detail the type of buffer overflow attacks and technical principles, so we have a good understanding of them, and then gives several common preventive measures.

  1. Atmospheric Delivery of Herbicides to Riparian Buffer Zones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have evaluated the ability of a riparian buffer to intercept herbicides from the air and deliver them directly by rainfall to a receiving stream in the buffer zone. The study was conducted over a four year period at a site in an agricultural watershed in Maryland. The rain collections included ...

  2. Microbial Community Diversity in Agroforestry and Grass Buffer Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agroforesty and grass buffer systems have long been promoted as a soil conservation practice that yields many environmental benefits. Previous research has described the ability of buffer systems to retain nutrients, slow water flow and soil erosion, or mitigate the potentially harmful effects of e...

  3. Methods for improved growth of group III nitride buffer layers

    DOEpatents

    Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

    2014-07-15

    Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphology of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).

  4. Amelogenins as Potential Buffers during Secretory-stage Amelogenesis

    PubMed Central

    Guo, J.; Lyaruu, D.M.; Takano, Y.; Gibson, C.W.; DenBesten, P.K.

    2015-01-01

    Amelogenins are the most abundant protein species in forming dental enamel, taken to regulate crystal shape and crystal growth. Unprotonated amelogenins can bind protons, suggesting that amelogenins could regulate the pH in enamel in situ. We hypothesized that without amelogenins the enamel would acidify unless ameloblasts were buffered by alternative ways. To investigate this, we measured the mineral and chloride content in incisor enamel of amelogenin-knockout (AmelX-/-) mice and determined the pH of enamel by staining with methyl-red. Ameloblasts were immunostained for anion exchanger-2 (Ae2), a transmembrane pH regulator sensitive for acid that secretes bicarbonate in exchange for chloride. The enamel of AmelX-/- mice was 10-fold thinner, mineralized in the secretory stage 1.8-fold more than wild-type enamel and containing less chloride (suggesting more bicarbonate secretion). Enamel of AmelX-/- mice stained with methyl-red contained no acidic bands in the maturation stage as seen in wild-type enamel. Secretory ameloblasts of AmelX-/- mice, but not wild-type mice, were immunopositive for Ae2, and stained more intensely in the maturation stage compared with wild-type mice. Exposure of AmelX-/- mice to fluoride enhanced the mineral content in the secretory stage, lowered chloride, and intensified Ae2 immunostaining in the enamel organ in comparison with non-fluorotic mutant teeth. The results suggest that unprotonated amelogenins may regulate the pH of forming enamel in situ. Without amelogenins, Ae2 could compensate for the pH drop associated with crystal formation. PMID:25535204

  5. Mitigation of substrate defects in reticles using multilayer buffer layers

    DOEpatents

    Mirkarimi, Paul B.; Bajt, Sasa; Stearns, Daniel G.

    2001-01-01

    A multilayer film is used as a buffer layer to minimize the size of defects on a reticle substrate prior to deposition of a reflective coating on the substrate. The multilayer buffer layer deposited intermediate the reticle substrate and the reflective coating produces a smoothing of small particles and other defects on the reticle substrate. The reduction in defect size is controlled by surface relaxation during the buffer layer growth process and by the degree of intermixing and volume contraction of the materials at the multilayer interfaces. The buffer layers are deposited at near-normal incidence via a low particulate ion beam sputtering process. The growth surface of the buffer layer may also be heated by a secondary ion source to increase the degree of intermixing and improve the mitigation of defects.

  6. Replenishing data descriptors in a DMA injection FIFO buffer

    DOEpatents

    Archer, Charles J.; Blocksome, Michael A.; Cernohous, Bob R.; Heidelberger, Philip; Kumar, Sameer; Parker, Jeffrey J.

    2011-10-11

    Methods, apparatus, and products are disclosed for replenishing data descriptors in a Direct Memory Access (`DMA`) injection first-in-first-out (`FIFO`) buffer that include: determining, by a messaging module on an origin compute node, whether a number of data descriptors in a DMA injection FIFO buffer exceeds a predetermined threshold, each data descriptor specifying an application message for transmission to a target compute node; queuing, by the messaging module, a plurality of new data descriptors in a pending descriptor queue if the number of the data descriptors in the DMA injection FIFO buffer exceeds the predetermined threshold; establishing, by the messaging module, interrupt criteria that specify when to replenish the injection FIFO buffer with the plurality of new data descriptors in the pending descriptor queue; and injecting, by the messaging module, the plurality of new data descriptors into the injection FIFO buffer in dependence upon the interrupt criteria.

  7. Enhancement of the absorption of CO{sub 2} in alkaline buffer solutions: Joint action of two enhancers

    SciTech Connect

    Vazquez, G.; Chenlo, F.; Pereira, G.; Vazquez, P.

    1999-05-01

    The authors measured the absorption of CO{sub 2} in alkaline 0.5 M/0.5 M sodium carbonate/bicarbonate buffers containing either saccharose and sodium arsenite or saccharose and formaldehyde. Absorption enhancement increased upon increasing the concentration of either of the catalysts, but the joint action of the two was always less than the sum of their individual effects, the difference being a function of the acidities and concentrations of the catalysts and the pH of the carbonate/bicarbonate buffer solution

  8. Effect of Tris-HCl buffer on DNA adsorption by a variety of soil constituents.

    PubMed

    Saeki, Kazutoshi; Kunito, Takashi; Sakai, Masao

    2011-01-01

    We investigated the effect of tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffer (pH 7.0) as a bulk solution on the adsorption of DNA by gibbsite, goethite, montmorillonite, kaolinite, synthetic and natural allophanes, two humic acids and two andosols. The natural allophane, gibbsite, kaolinite and an andosol adsorbed significantly more DNA in a 0.1 M Tris-HCl buffer than in a 0.1 M NaCl solution (t-test, P<0.005). In contrast, montmorillonite adsorbed significantly less DNA in the Tris-HCl than NaCl solution (P<0.05). Care should be taken when using Tris-HCl in studies on the adsorption of extracellular DNA molecules by soil particles. PMID:21487209

  9. Ultrathin Polyaniline-based Buffer Layer for Highly Efficient Polymer Solar Cells with Wide Applicability

    PubMed Central

    Zhao, Wenchao; Ye, Long; Zhang, Shaoqing; Fan, Bin; Sun, Mingliang; Hou, Jianhui

    2014-01-01

    Interfacial buffer layers often attribute the improved device performance in organic optoelectronic device. Herein, a water-soluble hydrochloric acid doped polyanilines (HAPAN) were utilized as p-type electrode buffer layer in highly efficient polymer solar cells (PSC) based on PBDTTT-EFT and several representative polymers. The PBDTTT-EFT-based conventional PSC featuring ultrathin HAPAN (1.3 nm) delivered high PCE approximately 9%, which is one of the highest values among conventional PSC devices. Moreover, ultrathin HAPAN also exhibited wide applicability in a variety of efficient photovoltaic polymers including PBDTTT-C-T, PTB7, PBDTBDD, PBTTDPP-T, PDPP3T and P3HT. The excellent performances were originated from the high transparency, small film roughness and suitable work function. PMID:25300365

  10. Getting Back to Basics (& Acidics)

    ERIC Educational Resources Information Center

    Rhodes, Sam

    2006-01-01

    This article describes a few novel acid-base experiments intended to introduce students to the basic concepts of acid-base chemistry and provide practical examples that apply directly to the study of biology and the human body. Important concepts such as the reaction between carbon dioxide and water, buffers and protein denaturation, are covered.…

  11. On the Preparation of Buffer Solutions.

    ERIC Educational Resources Information Center

    Thomson, Bruce M.; Kessick, Michael A.

    1981-01-01

    Presents a method, suitable for use on programmable calculators, which allows calculation of the pH and ionic strength (I) of a mixed solution of salts of an acid or amounts necessary to produce a solution of a particular pH and I. Includes limitations when using the calculations described. (SK)

  12. Multiple cytosolic calcium buffers in posterior pituitary nerve terminals.

    PubMed

    McMahon, Shane M; Chang, Che-Wei; Jackson, Meyer B

    2016-03-01

    Cytosolic Ca(2+) buffers bind to a large fraction of Ca(2+) as it enters a cell, shaping Ca(2+) signals both spatially and temporally. In this way, cytosolic Ca(2+) buffers regulate excitation-secretion coupling and short-term plasticity of release. The posterior pituitary is composed of peptidergic nerve terminals, which release oxytocin and vasopressin in response to Ca(2+) entry. Secretion of these hormones exhibits a complex dependence on the frequency and pattern of electrical activity, and the role of cytosolic Ca(2+) buffers in controlling pituitary Ca(2+) signaling is poorly understood. Here, cytosolic Ca(2+) buffers were studied with two-photon imaging in patch-clamped nerve terminals of the rat posterior pituitary. Fluorescence of the Ca(2+) indicator fluo-8 revealed stepwise increases in free Ca(2+) after a series of brief depolarizing pulses in rapid succession. These Ca(2+) increments grew larger as free Ca(2+) rose to saturate the cytosolic buffers and reduce the availability of Ca(2+) binding sites. These titration data revealed two endogenous buffers. All nerve terminals contained a buffer with a Kd of 1.5-4.7 µM, and approximately half contained an additional higher-affinity buffer with a Kd of 340 nM. Western blots identified calretinin and calbindin D28K in the posterior pituitary, and their in vitro binding properties correspond well with our fluorometric analysis. The high-affinity buffer washed out, but at a rate much slower than expected from diffusion; washout of the low-affinity buffer could not be detected. This work has revealed the functional impact of cytosolic Ca(2+) buffers in situ in nerve terminals at a new level of detail. The saturation of these cytosolic buffers will amplify Ca(2+) signals and may contribute to use-dependent facilitation of release. A difference in the buffer compositions of oxytocin and vasopressin nerve terminals could contribute to the differences in release plasticity of these two hormones. PMID:26880753

  13. Acid-base chemistry

    SciTech Connect

    Hand, C.W.; Blewit, H.L.

    1985-01-01

    The book is not a research compendium and there are no references to the literature. It is a teaching text covering the entire range of undergraduate subject matter dealing with acid-base chemistry (some of it remotely) as taught in inorganic, analytical, and organic chemistry courses. The excellent chapters VII through IX deal in detail with the quantitative aspects of aqueous acid-base equilibria (salt hydrolysis and buffer, titrations, polyprotic and amphoteric substances).

  14. One-pot non-enzymatic formation of firefly luciferin in a neutral buffer from p-benzoquinone and cysteine

    PubMed Central

    Kanie, Shusei; Nishikawa, Toshio; Ojika, Makoto; Oba, Yuichi

    2016-01-01

    Firefly luciferin, the substrate for the bioluminescence reaction of luminous beetles, possesses a benzothiazole ring, which is rare in nature. Here, we demonstrate a novel one-pot reaction to give firefly luciferin in a neutral buffer from p-benzoquinone and cysteine without any synthetic reagents or enzymes. The formation of firefly luciferin was low in yield in various neutral buffers, whereas it was inhibited or completely prevented in acidic or basic buffers, in organic solvents, or under a nitrogen atmosphere. Labelling analysis of the firefly luciferin using stable isotopic cysteines showed that the benzothiazole ring was formed via the decarboxylation and carbon-sulfur bond rearrangement of cysteine. These findings imply that the biosynthesis of firefly luciferin can be developed/evolved from the non-enzymatic production of firefly luciferin using common primary biosynthetic units, p-benzoquinone and cysteine. PMID:27098929

  15. One-pot non-enzymatic formation of firefly luciferin in a neutral buffer from p-benzoquinone and cysteine.

    PubMed

    Kanie, Shusei; Nishikawa, Toshio; Ojika, Makoto; Oba, Yuichi

    2016-01-01

    Firefly luciferin, the substrate for the bioluminescence reaction of luminous beetles, possesses a benzothiazole ring, which is rare in nature. Here, we demonstrate a novel one-pot reaction to give firefly luciferin in a neutral buffer from p-benzoquinone and cysteine without any synthetic reagents or enzymes. The formation of firefly luciferin was low in yield in various neutral buffers, whereas it was inhibited or completely prevented in acidic or basic buffers, in organic solvents, or under a nitrogen atmosphere. Labelling analysis of the firefly luciferin using stable isotopic cysteines showed that the benzothiazole ring was formed via the decarboxylation and carbon-sulfur bond rearrangement of cysteine. These findings imply that the biosynthesis of firefly luciferin can be developed/evolved from the non-enzymatic production of firefly luciferin using common primary biosynthetic units, p-benzoquinone and cysteine. PMID:27098929

  16. Improved ultrastructure of marine invertebrates using non-toxic buffers

    PubMed Central

    Montanaro, Jacqueline; Gruber, Daniela

    2016-01-01

    Many marine biology studies depend on field work on ships or remote sampling locations where sophisticated sample preservation techniques (e.g., high-pressure freezing) are often limited or unavailable. Our aim was to optimize the ultrastructural preservation of marine invertebrates, especially when working in the field. To achieve chemically-fixed material of the highest quality, we compared the resulting ultrastructure of gill tissue of the mussel Mytilus edulis when fixed with differently buffered EM fixatives for marine specimens (seawater, cacodylate and phosphate buffer) and a new fixative formulation with the non-toxic PHEM buffer (PIPES, HEPES, EGTA and MgCl2). All buffers were adapted for immersion fixation to form an isotonic fixative in combination with 2.5% glutaraldehyde. We showed that PHEM buffer based fixatives resulted in equal or better ultrastructure preservation when directly compared to routine standard fixatives. These results were also reproducible when extending the PHEM buffered fixative to the fixation of additional different marine invertebrate species, which also displayed excellent ultrastructural detail. We highly recommend the usage of PHEM-buffered fixation for the fixation of marine invertebrates. PMID:27069800

  17. Gilliam County Riparian Buffers; 2003-2004 Annual Reports.

    SciTech Connect

    Coiner, Josh

    2004-06-01

    Interest appears to be at an all-time high for riparian conservation programs in Gilliam County. With the recently added Herbaceous Buffer and the already established CREP program interest is booming. However, more and more people are turning towards the herbaceous buffer because of expense. The riparian forest buffer is becoming too expensive. Even with the excellent cost share and incentives landowners are having trouble with Farm Service Agency's payment limitation. Because of this payment limitation landowners are not receiving their full rental and incentive payments, usually in year one. This has cooled the installation of riparian forest buffers and peaked interest in the CP-29 (Herbaceous Buffer for Wildlife). Either way, riparian lands are being enhanced and water quality is being improved. Year three should be very similar to the accomplishments of year 2. There has already been several projects proposed that may or may not be approved during year 3. I am currently working on three projects that are all over 2.5 miles long on each side and total anywhere from 60 to 250 acres in size. Along with these three projects there at least seven small projects being proposed. Four of those projects are riparian forest buffers and the remaining are herbaceous buffers.

  18. Molecular Buffers Permit Sensitivity Tuning and Inversion of Riboswitch Signals

    PubMed Central

    2016-01-01

    Predictable integration of foreign biological signals and parts remains a key challenge in the systematic engineering of synthetic cellular actuations, and general methods to improve signal transduction and sensitivity are needed. To address this problem we modeled and built a molecular signal buffer network in Saccharomyces cerevisiae inspired by chemical pH buffer systems. The molecular buffer system context-insulates a riboswitch enabling synthetic control of colony formation and modular signal manipulations. The riboswitch signal is relayed to a transcriptional activation domain of a split transcription factor, while interacting DNA-binding domains mediate the transduction of signal and form an interacting molecular buffer. The molecular buffer system enables modular signal inversion through integration with repressor modules. Further, tuning of input sensitivity was achieved through perturbation of the buffer pair ratio guided by a mathematical model. Such buffered signal tuning networks will be useful for domestication of RNA-based sensors enabling tunable outputs and library-wide selections for drug discovery and metabolic engineering. PMID:27138234

  19. Improved ultrastructure of marine invertebrates using non-toxic buffers.

    PubMed

    Montanaro, Jacqueline; Gruber, Daniela; Leisch, Nikolaus

    2016-01-01

    Many marine biology studies depend on field work on ships or remote sampling locations where sophisticated sample preservation techniques (e.g., high-pressure freezing) are often limited or unavailable. Our aim was to optimize the ultrastructural preservation of marine invertebrates, especially when working in the field. To achieve chemically-fixed material of the highest quality, we compared the resulting ultrastructure of gill tissue of the mussel Mytilus edulis when fixed with differently buffered EM fixatives for marine specimens (seawater, cacodylate and phosphate buffer) and a new fixative formulation with the non-toxic PHEM buffer (PIPES, HEPES, EGTA and MgCl2). All buffers were adapted for immersion fixation to form an isotonic fixative in combination with 2.5% glutaraldehyde. We showed that PHEM buffer based fixatives resulted in equal or better ultrastructure preservation when directly compared to routine standard fixatives. These results were also reproducible when extending the PHEM buffered fixative to the fixation of additional different marine invertebrate species, which also displayed excellent ultrastructural detail. We highly recommend the usage of PHEM-buffered fixation for the fixation of marine invertebrates. PMID:27069800

  20. Social buffering ameliorates conditioned fear responses in female rats.

    PubMed

    Ishii, Akiko; Kiyokawa, Yasushi; Takeuchi, Yukari; Mori, Yuji

    2016-05-01

    The stress experienced by an animal is ameliorated when the animal is exposed to distressing stimuli along with a conspecific animal(s). This is known as social buffering. Previously, we found that the presence of an unfamiliar male rat induced social buffering and ameliorated conditioned fear responses of a male rat subjected to an auditory conditioned stimulus (CS). However, because our knowledge of social buffering is highly biased towards findings in male subjects, analyses using female subjects are crucial for comprehensively understanding the social buffering phenomenon. In the present studies, we assessed social buffering of conditioned fear responses in female rats. We found that the estrus cycle did not affect the intensity of the rats' fear responses to the CS or their degree of vigilance due to the presence of a conspecific animal. Based on these findings, we then assessed whether social buffering ameliorated conditioned fear responses in female rats without taking into account their estrus cycles. When fear conditioned female rats were exposed to the CS without the presence of a conspecific, they exhibited behavioral responses, including freezing, and elevated corticosterone levels. By contrast, the presence of an unfamiliar female rat suppressed these responses. Based on these findings, we conclude that social buffering can ameliorate conditioned fear responses in female rats. PMID:27060333

  1. Buffer Gas Experiments in Mercury (Hg+) Ion Clock

    NASA Technical Reports Server (NTRS)

    Chung, Sang K.; Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2004-01-01

    We describe the results of the frequency shifts measured from various buffer gases that might be used as a buffer gas to increase the loading efficiency and cooling of ions trapped in a small mercury ion clock. The small mass, volume and power requirement of space clock precludes the use of turbo pumps. Hence, a hermetically sealed vacuum system, incorporating a suitable getter material with a fixed amount of inert buffer gas may be a practical alternative to the groundbased system. The collision shifts of 40,507,347.996xx Hz clock transition for helium, neon and argon buffer gases were measured in the ambient earth magnetic field. In addition to the above non-getterable inert gases we also measured the frequency shifts due to getterable, molecular hydrogen and nitrogen gases which may be used as buffer gases when incorporated with a miniature ion pump. We also examined the frequency shift due to the low methane gas partial pressure in a fixed higher pressure neon buffer gas environment. Methane gas interacted with mercury ions in a peculiar way as to preserve the ion number but to relax the population difference in the two hyperfine clock states and thereby reducing the clock resonance signal. The same population relaxation was also observed for other molecular buffer gases (N H,) but at much reduced rate.

  2. Monitoring Liverworts to Evaluate the Effectiveness of Hydroriparian Buffers

    NASA Astrophysics Data System (ADS)

    Higgins, Kellina L.; Yasué, Maï

    2014-01-01

    In the coastal temperate rainforest of British Columbia (BC) in western Canada, government policies stipulate that foresters leave unlogged hydroriparian buffer strips up to 25 m on each side of streams to protect wildlife habitat. At present, studies on the effectiveness of these buffers focus on mammals, birds, and amphibians while there is comparably little information on smaller organisms such as liverworts in these hydroriparian buffers. To address this gap of knowledge, we conducted field surveys of liverworts comparing the percent cover and community composition in hydroriparian forested areas ( n = 4 sites, n = 32 plots with nested design) to hydroriparian buffer zones ( n = 4 sites, n = 32 plots). We also examined how substrate type affected the cover of liverworts. Liverwort communities in buffers were similar to those in riparian forest areas and most liverworts were found on downed wood. Thus, hydroriparian buffers of 25-35 m on each side in a coastal temperate rainforest effectively provide habitat for liverworts as long as downed wood is left intact in the landscape. Because liverworts are particularly sensitive to changes in humidity, these results may indicate that hydroriparian buffers are an effective management strategy for bryophytes and possibly for a range of other riparian species that are particularly sensitive to forestry-related changes in microclimate.

  3. Molecular Buffers Permit Sensitivity Tuning and Inversion of Riboswitch Signals.

    PubMed

    Rugbjerg, Peter; Genee, Hans Jasper; Jensen, Kristian; Sarup-Lytzen, Kira; Sommer, Morten Otto Alexander

    2016-07-15

    Predictable integration of foreign biological signals and parts remains a key challenge in the systematic engineering of synthetic cellular actuations, and general methods to improve signal transduction and sensitivity are needed. To address this problem we modeled and built a molecular signal buffer network in Saccharomyces cerevisiae inspired by chemical pH buffer systems. The molecular buffer system context-insulates a riboswitch enabling synthetic control of colony formation and modular signal manipulations. The riboswitch signal is relayed to a transcriptional activation domain of a split transcription factor, while interacting DNA-binding domains mediate the transduction of signal and form an interacting molecular buffer. The molecular buffer system enables modular signal inversion through integration with repressor modules. Further, tuning of input sensitivity was achieved through perturbation of the buffer pair ratio guided by a mathematical model. Such buffered signal tuning networks will be useful for domestication of RNA-based sensors enabling tunable outputs and library-wide selections for drug discovery and metabolic engineering. PMID:27138234

  4. Wasco Riparian Buffer Project, Annual Report 2003-2004.

    SciTech Connect

    Graves, Ron

    2003-07-01

    This project implements riparian buffer systems in the Mid-Columbia, addressing limiting factors identified in the Deschutes River Sub-basin Summary, March 2, 2001. This project is providing the technical planning support needed to implement at least 20 riparian buffer system contracts on approximately 800 acres covering an estimated 36 miles of anadromous fish streams. During this second year of implementation, 17 buffer contracts were established on 173,462 ft. of stream (25.9 miles). Acreage included in the buffers totaled 891.6 acres. Average buffer width was 112 ft. on each side of the stream. Cumulative totals through the first two project years are 26 buffers on 36.6 stream miles covering 1,283.6 acres. Actual implementation costs, lease payments, and maintenance costs will be borne by existing USDA programs: Conservation Reserve (CRP) and Conservation Reserve Enhancement Programs (CREP). The lease period of each contract may vary from 10 to 15 years. During this year, the average lease period was 14.9 years. The total value of contracts established this year is $1,421,268 compared with $55,504 in BPA contract costs to provide the technical support needed to get the contracts implemented. Cumulative contract value for the first two years is $1,919,451 compared to $103,329 cost to BPA. This project provides technical staffing to conduct assessments and develop conservation plans required for riparian buffer systems to help keep pace with a growing backlog of potential buffer projects. This project meets a critical need in the lower Deschutes and lower John Day River basins and complements the Riparian Buffer project approved for Fifteenmile watershed, Project No. 2001-021-00 begun in fiscal year 2001. This project supports RPA 150 and 153 as required under the Federal Hydropower System biological opinion and benefits the mid-Columbia ESU of steelhead.

  5. Protein buffering in model systems and in whole human saliva.

    PubMed

    Lamanda, Andreas; Cheaib, Zeinab; Turgut, Melek Dilek; Lussi, Adrian

    2007-01-01

    The aim of this study was to quantify the buffer attributes (value, power, range and optimum) of two model systems for whole human resting saliva, the purified proteins from whole human resting saliva and single proteins. Two model systems, the first containing amyloglucosidase and lysozyme, and the second containing amyloglucosidase and alpha-amylase, were shown to provide, in combination with hydrogencarbonate and di-hydrogenphosphate, almost identical buffer attributes as whole human resting saliva. It was further demonstrated that changes in the protein concentration as small as 0.1% may change the buffer value of a buffer solution up to 15 times. Additionally, it was shown that there was a protein concentration change in the same range (0.16%) between saliva samples collected at the time periods of 13:00 and others collected at 9:00 am and 17:00. The mode of the protein expression changed between these samples corresponded to the change in basic buffer power and the change of the buffer value at pH 6.7. Finally, SDS Page and Ruthenium II tris (bathophenantroline disulfonate) staining unveiled a constant protein expression in all samples except for one 50 kDa protein band. As the change in the expression pattern of that 50 kDa protein band corresponded to the change in basic buffer power and the buffer value at pH 6.7, it was reasonable to conclude that this 50 kDa protein band may contain the protein(s) belonging to the protein buffer system of human saliva. PMID:17327922

  6. Lightweight, durable lead-acid batteries

    DOEpatents

    Lara-Curzio, Edgar; An, Ke; Kiggans, Jr., James O; Dudney, Nancy J; Contescu, Cristian I; Baker, Frederick S; Armstrong, Beth L

    2013-05-21

    A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

  7. Lightweight, durable lead-acid batteries

    DOEpatents

    Lara-Curzio, Edgar; An, Ke; Kiggans, Jr., James O.; Dudney, Nancy J.; Contescu, Cristian I.; Baker, Frederick S.; Armstrong, Beth L.

    2011-09-13

    A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

  8. Buffer layers for REBCO films for use in superconducting devices

    DOEpatents

    Goyal, Amit; Wee, Sung-Hun

    2014-06-10

    A superconducting article includes a substrate having a biaxially textured surface. A biaxially textured buffer layer, which can be a cap layer, is supported by the substrate. The buffer layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different transition metal cations. A biaxially textured superconductor layer is deposited so as to be supported by the buffer layer. A method of making a superconducting article is also disclosed.

  9. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    DOEpatents

    Bajikar, Sateesh S.; De Carlo, Francesco; Song, Joshua J.

    2001-01-01

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  10. An oxygen buffer for some peraluminous granites and metamorphic rocks.

    USGS Publications Warehouse

    Zen, E.

    1985-01-01

    The mineral assemblage biotite-garnet-muscovite-magnetite-quartz and its sub-sets are common in many peraluminous granites, schists and gneisses. If the biotite and garnet are reasonably iron-rich, then the system is a useful buffer for fO2. Available thermochemical data indicate that, in T-fO2 space, the buffer curve is located between the hematite-magnetite curve and the quartz-magnetite-fayalite curve, in a region that previously had no buffer curve applicable to peraluminous rocks. -J.A.Z.

  11. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    SciTech Connect

    Bajikar, Sateesh S.; De Carlo, Francesco; Song, Joshua J.

    2004-01-27

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  12. Capacity and buffer trade-offs in a remanufacturing system

    NASA Astrophysics Data System (ADS)

    Aksoy, Hasan K.; Gupta, Surendra M.

    2002-02-01

    In this paper, we examine the tradeoffs between increasing the number of buffers and increasing the capacity at the remanufacturing stations under numerous circumstances on such performance measures as expected total cost, average WIP inventory, throughput and average processing (remanufacturing) time when the remanufacturing stations are operating in uncertain environments. We model the remanufacturing system using an open queueing network with finite buffers and unreliable servers. In order to analyze the queueing network, we use the decomposition principle and expansion methodology. Each server in the system is subject to breakdown and has a finite buffer capacity.

  13. Job Shop Scheduling Focusing on Role of Buffer

    NASA Astrophysics Data System (ADS)

    Hino, Rei; Kusumi, Tetsuya; Yoo, Jae-Kyu; Shimizu, Yoshiaki

    A scheduling problem is formulated in order to consistently manage each manufacturing resource, including machine tools, assembly robots, AGV, storehouses, material shelves, and so on. The manufacturing resources are classified into three types: producer, location, and mover. This paper focuses especially on the role of the buffer, and the differences among these types are analyzed. A unified scheduling formulation is derived from the analytical results based on the resource’s roles. Scheduling procedures based on dispatching rules are also proposed in order to numerically evaluate job shop-type production having finite buffer capacity. The influences of the capacity of bottle-necked production devices and the buffer on productivity are discussed.

  14. Buffer layer effect on ZnO nanorods growth alignment

    NASA Astrophysics Data System (ADS)

    Zhao, Dongxu; Andreazza, Caroline; Andreazza, Pascal; Ma, Jiangang; Liu, Yichun; Shen, Dezhen

    2005-06-01

    Vertical aligned ZnO nanorods array was fabricated on Si with introducing a ZnO thin film as a buffer layer. Two different nucleation mechanisms were found in growth process. With using Au catalyst, Zn vapor could diffuse into Au nanoclusters with forming a solid solution. Then the ZnO nucleation site is mainly on the catalyst by oxidation of Au/Zn alloy. Without catalyst, nucleation could occur directly on the surface of buffer layer by homoepitaxy. The density and the size of ZnO nanorods could be governed by morphological character of catalyst and buffer layer. The nanorods growth is followed by vapor-solid mechanism.

  15. MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex

    PubMed Central

    Kagenishi, Tomoko; Yokawa, Ken; Baluška, František

    2016-01-01

    In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species (ROS). MES, 2-(N-morpholino)ethanesulfonic acid as one of the Good’s buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v) because the buffer capacity of MES ranging pH 5.5–7.0 (for Arabidopsis, pH 5.8). However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone, and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone). Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the ROS homeostasis in root apex. PMID:26925066

  16. MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex.

    PubMed

    Kagenishi, Tomoko; Yokawa, Ken; Baluška, František

    2016-01-01

    In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species (ROS). MES, 2-(N-morpholino)ethanesulfonic acid as one of the Good's buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v) because the buffer capacity of MES ranging pH 5.5-7.0 (for Arabidopsis, pH 5.8). However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone, and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone). Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the ROS homeostasis in root apex. PMID:26925066

  17. Highly smooth Nb surfaces fabricated by buffered electropolishing

    SciTech Connect

    Andy T. Wu; John Mammossor; H. Phillips; Jean Delayen; Charles Reece; Amy Wilkerson; David Smith; Robert Ike

    2005-05-01

    It is demonstrated that highly smooth Nb surfaces can be obtained through Buffered ElectroPolishing (BEP) employing an electrolyte consisting of lactic, sulfuric, and hydrofluoric acids. Parameters that control the polishing process are optimized to achieve the smoothest surface finish with the help of surface observations using a scanning electron microscope and a Metallographic Optical Microscope (MOM). The polishing rate of BEP is determined to be 0.646 {micro}m/min that is much higher than 0.381 {micro}m/min achieved by the conventional ElectroPolishing (EP) process widely used in the Superconducting Radio Frequency (SRF) community. A high precision and large scan area 3-D profilometer is used to view morphology of the treated Nb surfaces. Statistical data, such as, rms, total indicator runout, and arithmetic mean deviation of the Nb surfaces are extracted from the profilometer images. It is found that Nb surfaces treated by BEP are an order of magnitude smoother than those treated by the optimized EP process. The chemical composition of the Nb surfaces after BEP is analyzed by static and dynamic Secondary Ion Mass Spectrometer (SIMS) systems. Cracking patterns of the Nb surfaces under different primary ion sources of Ga{sup +}, Au{sup +}, and Ar{sup +} are reported. The depth profile of the surface niobium oxides is studied through continuously monitoring niobium and its relevant oxides' peaks as a function of time. Dynamic SIMS results imply that the surface oxide structure of Nb may be more complicated than what usually believed and can be inhomogeneous. Preliminary results of BEP on Nb SRF single cell cavities and half-cells are reported. It is shown that smooth and bright surfaces can be obtained in 30 minutes when the electric field inside a SRF cavity is uniform during a BEP process. This study reveals that BEP is a highly promising technique for surface treatment on Nb SRF cavities to be used in particle accelerators.

  18. Aggregation and other intermolecular interactions of biological buffers observed by capillary electrophoresis and UV photometry.

    PubMed

    Vespalec, R; Vlcková, M; Horáková, H

    2004-10-01

    Electrophoretic and photometric experiments strongly indicate that monovalent anions, which arise by deprotonation of the nitrogen atom in zwitterionic Good's buffers 3-(cyclohexylamino)-2-hydroxy-1-propanesulfonic acid (CAPSO) and 3-morpholinopropanesulfonic acid (MOPS), spontaneously aggregate. Cationic migration of sanguinarine (SA) and chelerythrine (CHE) in highly alkaline 1,3-bis[tris(hydroxymethyl)methylamino]propane (Bis-Tris-propane), in which the concentration of cations of both alkaloids is negligible, may be explained by the existence of an aggregate, which contains uncharged sanguinarine or chelerythrine and one monovalent cation of Bis-Tris-propane at least. Tendency of tris(hydroxymethyl)aminomethane (Tris), bis (2-hydroxyethyl)iminotris(hydroxymethyl)methane (Bis-Tris) and Bis-Tris-propane cations to ion pairing with synthetic cluster borane anions and with fused silica markedly rises up with the size and charge of these cations. The drop in mobility of cluster borane compounds sometimes exceeds 50% of their mobility found at identical pH and ionic strength in buffers with sodium cation. The electroosmosis drop approached 70% if background electrolyte contained Bis-Tris-propane cations instead of sodium cations. Nitrate, taken as a model inorganic ion, and four randomly chosen organic anions interacted markedly less with Tris, Bis-Tris and Bis-Tris-propane cations than cluster borane anions. 2-(N-morpholino)ethanesulfonic (MES) acid anions present in background electrolyte affect the ion pairing of Tris, Bis-Tris and Bis-Tris-propane cations with anionic analytes and, in this way influence also mobilites of these anionic analytes. Limited hydrophilicity at least one of interacting species appears to be the most probable cause of observed intermolecular interactions of biological buffers. PMID:15532558

  19. Radiation resistance of the natural microbial population in buffer materials

    SciTech Connect

    Stroes-Gascoyne, S.; Lucht, L.M.; Borsa, J.; Delaney, T.L.; Haveman, S.A.; Hamon, C.J.

    1995-12-31

    The radiation sensitivity of naturally occurring microorganisms in buffer materials was investigated as well as the sensitivity of Bacillus subtillis spores and Acinetobacter radioresistens in a buffer matrix. The D{sub 10} values obtained in these radiation experiments varied from 0.34 to 1.68 kGy and it was calculated that the surface of a nuclear fuel waste container would be sterilized in 9 to 33 d after emplacement, depending on the type of container, and the initial bioburden. This suggests that formation of biofilms and microbially influenced corrosion would not be of concern of some time after emplacement. The results also indicated that sterilization throughout a 25 cm thick buffer layer is unlikely and that repopulation of the container surface after some time is a possibility, depending on the mobility of microbes in compacted buffer material.

  20. On buffer layers as non-reflecting computational boundaries

    NASA Technical Reports Server (NTRS)

    Hayder, M. Ehtesham; Turkel, Eli L.

    1996-01-01

    We examine an absorbing buffer layer technique for use as a non-reflecting boundary condition in the numerical simulation of flows. One such formulation was by Ta'asan and Nark for the linearized Euler equations. They modified the flow inside the buffer zone to artificially make it supersonic in the layer. We examine how this approach can be extended to the nonlinear Euler equations. We consider both a conservative and a non-conservative form modifying the governing equations in the buffer layer. We compare this with the case that the governing equations in the layer are the same as in the interior domain. We test the effectiveness of these buffer layers by a simulation of an excited axisymmetric jet based on a nonlinear compressible Navier-Stokes equations.

  1. Analysis of a unidirectional, symmetric buffer strip laminate with damage

    NASA Technical Reports Server (NTRS)

    Dharani, L. R.; Goree, J. G.

    1984-01-01

    A method for predicting the fracture behavior of hybrid buffer strip laminates is presented in which the classical shear-lag model is used to represent the shear stress distribution between adjacent fibers. The method is demonstrated by applying it to a notched graphite/epoxy laminate, and the results show clearly the manner in which the most efficient combination of buffer strip properties can be selected in order to arrest the crack. The ultimate failure stress of the laminate is plotted vs the buffer strip width. It is shown that in the case of graphite-epoxy and S-glass epoxy laminates, the optimum buffer strip spacing to width ratio should be about four to one.

  2. Religion a Buffer Against Suicide for Women, Study Suggests

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_159630.html Religion a Buffer Against Suicide for Women, Study Suggests ... encouraged as a form of meaningful social participation. Religion and spirituality may be an underappreciated resource that ...

  3. Optimizing the availability of a buffered industrial process

    DOEpatents

    Martz, Jr., Harry F.; Hamada, Michael S.; Koehler, Arthur J.; Berg, Eric C.

    2004-08-24

    A computer-implemented process determines optimum configuration parameters for a buffered industrial process. A population size is initialized by randomly selecting a first set of design and operation values associated with subsystems and buffers of the buffered industrial process to form a set of operating parameters for each member of the population. An availability discrete event simulation (ADES) is performed on each member of the population to determine the product-based availability of each member. A new population is formed having members with a second set of design and operation values related to the first set of design and operation values through a genetic algorithm and the product-based availability determined by the ADES. Subsequent population members are then determined by iterating the genetic algorithm with product-based availability determined by ADES to form improved design and operation values from which the configuration parameters are selected for the buffered industrial process.

  4. RESEARCH SHOWS IMPORTANCE OF RIPARIAN BUFFERS FOR AQUATIC HEALTH

    EPA Science Inventory

    Issue: Excess nitrogen from fertilizer, septic tanks, animal feedlots, and runoff from pavement can threaten aquatic ecosystem health. Riparian buffers -- the vegetated region adjacent to streams and wetlands -- are thought to be effective at intercepting and controlling excess ...

  5. Evidence for positive mood buffering among college student drinkers.

    PubMed

    Mohr, Cynthia D; Brannan, Debi; Mohr, Josh; Armeli, Stephen; Tennen, Howard

    2008-09-01

    Positive experiences play an important role in buffering the effects of negative experiences. Although this process can play out in a myriad of contexts, the college context is one of particular importance because of significant concerns about student stress levels and alcohol abuse. Building on evidence that at least some students drink in response to negative experiences, we considered the possibility that positive moods would moderate college student negative mood-drinking relationships. Using a Web-based daily process study of 118 (57% women) undergraduate student drinkers, the authors reveal that positive moods indeed buffer the effects of negative moods on student drinking, depending on the mood and drinking context. Furthermore, the buffering of ashamed mood appears to explain the buffering of other negative moods. Implications of these findings are considered in terms of the relationship between negative self-awareness and drinking to cope. PMID:18550862

  6. 4. EAST FACE. VEGETATIVE SCREENS BUFFER THE BUILDING FROM INDUSTRIAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. EAST FACE. VEGETATIVE SCREENS BUFFER THE BUILDING FROM INDUSTRIAL AREAS TO THE SOUTH OF OARB. - Oakland Army Base, General Purpose Administration Building, Chungking & Algiers Streets, Oakland, Alameda County, CA

  7. Religion a Buffer Against Suicide for Women, Study Suggests

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_159630.html Religion a Buffer Against Suicide for Women, Study Suggests ... encouraged as a form of meaningful social participation. Religion and spirituality may be an underappreciated resource that ...

  8. Buffer layers for high-Tc thin films on sapphire

    NASA Technical Reports Server (NTRS)

    Wu, X. D.; Foltyn, S. R.; Muenchausen, R. E.; Cooke, D. W.; Pique, A.; Kalokitis, D.; Pendrick, V.; Belohoubek, E.

    1992-01-01

    Buffer layers of various oxides including CeO2 and yttrium-stabilized zirconia (YSZ) have been deposited on R-plane sapphire. The orientation and crystallinity of the layers were optimized to promote epitaxial growth of YBa2Cu3O(7-delta) (YBCO) thin films. An ion beam channeling minimum yield of about 3 percent was obtained in the CeO2 layer on sapphire, indicating excellent crystallinity of the buffer layer. Among the buffer materials used, CeO2 was found to be the best one for YBCO thin films on R-plane sapphire. High Tc and Jc were obtained in YBCO thin films on sapphire with buffer layers. Surface resistances of the YBCO films were about 4 mOmega at 77 K and 25 GHz.

  9. Performance of organic photovoltaics using an ytterbium trifluoride n-type buffer layer

    NASA Astrophysics Data System (ADS)

    Ji, Chan Hyuk; Jang, Ji Min; Oh, Se Young

    2016-03-01

    Ytterbium trifluoride (YbF3) was used as an n-type cathode buffer layer in conventional poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PC60BM) bulk heterojunction (BHJ) organic photovoltaic cells. This buffer layer acts as an electron-transport layer and improves the open circuit voltage ( V oc), power conversion efficiency (PCE), and interfacial durability of the device. The physical properties and performance of the device were studied using impedance spectroscopy, photocurrent measurements, ultraviolet photoelectron spectroscopy, and atomic force microscopy. The PCE reached to 3.2% with a 65% fill factor under 1 sun irradiation. The PCE decreased to half of its original value after 120 h at room temperature in air or 24 h at 70°C in air. Comparison with Yb and TiOx cathode buffer layers reveals that YbF3 has superior performance and longevity. These findings suggest that YbF3 has the potential to replace costly device encapsulation. [Figure not available: see fulltext.

  10. Evaluating the buffering capacity of various soft drinks, fruit juices and tea

    PubMed Central

    Singh, Smita; Jindal, Rahul

    2010-01-01

    Aims and Objective: The purpose of this study is to measure the initial pH of various commonly used beverages and to determine their ability to maintain a low pH by measuring their buffering capacities. Materials and Methods: Twelve commercially available drinks were taken and divided into four groups (preserved fruit juices, tea, mineral water and carbonated drinks. Each group comprised of three drinks. Their initial pH were measured with pH meter and their buffering capacities were measured by adding 1M NaOH in the increments of 0.2 ml into 100 ml of each drink till the pH raised to 5.5 and 7 respectively. Statistical Analysis: The volume of NaOH required to raise the pH to 5.5 and 7 were recorded in all the groups. This data was subjected to statistical analysis using Mann- Whitney tests. Results: Total titratable acidity measurement shows that among all the drinks, there was no significant difference between carbonated drinks and preserved fruit juices while a significant difference was present between carbonated drinks, preserved fruit juices and tea. Conclusion: In this in vitro study, it was found that packaged apple juice had the most buffering capacity with maximum erosive potential whereas green tea had the least. PMID:21116386

  11. Using a Buffer Gas Modifier to Change Separation Selectivity in Ion Mobility Spectrometry

    PubMed Central

    Fernández-Maestre, Roberto; Wu, Ching; Hill, Herbert H.

    2010-01-01

    The mobilities of a set of common α-amino acids, four tetraalkylammonium ions, 2,4-dimethyl pyridine (2,4-lutidine), 2,6-di-tert-butyl pyridine (DTBP), and valinol were determined using electrospray ionization-ion mobility spectrometry-quadrupole mass spectrometry (ESI-IMS-QMS) while introducing 2-butanol into the buffer gas. The mobilities of the test compounds decreased by varying extents with 2-butanol concentration in the mobility spectrometer. When the concentration of 2-butanol increased from 0.0 to 6.8 mmol m−3 (2.5×102 ppmv), percentage reductions in mobilities were: 13.6% (serine), 12.2% (threonine), 10.4% (methionine), 10.3% (tyrosine), 9.8% (valinol), 9.2% (phenylalanine), 7.8% (tryptophan), 5.6% (2,4-lutidine), 2.2% (DTBP), 1.0% (tetramethylammonium ion, TMA, and tetraethylammonium ion, TEA), 0.0% (tetrapropylammonium ion, TPA), and 0.3% (tetrabutylammonium ion, TBA). These variations in mobility depended on the size and steric hindrance on the charge of the ions, and were due to formation of large ion-2-butanol clusters. This selective variation in mobilities was applied to the resolution of a mixture of compounds with similar reduced mobilities such as serine and valinol, which overlapped in N2-only buffer gas in the IMS spectrum. The relative insensitivity of tetraalkylammonium ions and DTBP to the introduction of 2-butanol into the buffer gas was explained by steric hindrance of the four alkyl substituents in tetraalkylammonium ions and the two tert-butyl groups in DTBP, which shielded the positive charge of the ion from the attachment of 2-butanol molecules. Low buffer gas temperatures (100 °C) produced the largest reductions in mobilities by increasing ion-2-butanol interactions and formation of clusters; high temperatures (250 °C) prevented the formation of clusters, and no reduction in ion mobility was obtained with the introduction of 2-butanol into the buffer gas. Low temperatures and high concentrations of 2-butanol produced a series of

  12. Carbon dioxide in the ocean surface: The homogeneous buffer factor

    USGS Publications Warehouse

    Sundquist, E.T.; Plummer, L.N.; Wigley, T.M.L.

    1979-01-01

    The amount of carbon dioxide that can be dissolved in surface seawater depends at least partially on the homogeneous buffer factor, which is a mathematical function of the chemical equilibrium conditions among the various dissolved inorganic species. Because these equilibria are well known, the homogeneous buffer factor is well known. Natural spatial variations depend very systematically on sea surface temperatures, and do not contribute significantly to uncertainties in the present or future carbon dioxide budget. Copyright ?? 1979 AAAS.

  13. Driving forces and the influence of the buffer composition on the complexation reaction between ibuprofen and HPCD.

    PubMed

    Perlovich, German L; Skar, Merete; Bauer-Brandl, Annette

    2003-10-01

    Cyclodextrins are often used in order to increase the aqueous solubility of drug substances by complexation. In order to investigate the complexation reaction of ibuprofen and hydroxypropyl-beta-cyclodextrin, titration calorimetry was used as a direct method. The thermodynamic parameters of the complexation process (stability constant, K(11); complexation enthalpy, deltaH(c) degrees ) were obtained in two different buffer systems (citric acid/sodium-phosphate and phosphoric acid) at various pH values. Based on these data the relative contributions of the enthalpic and entropic terms of the Gibbs energy to the complexation process have been analyzed. In both buffers the enthalpic and entropic terms are of different sign and this case corresponds to a 'nonclassical' model of hydrophobic interaction. In citric buffer, the main driving force of complexation is the entropy, which increases from 60 to 67% while the pH of the solution increases from 3.2 to 8.0. However, for the phosphoric buffer the entropic term decreases from 60 to 45%, while the pH-value of the solution increases from 5.0 to 8.2, and the driving force of the complexation process changes from entropy to enthalpy. The experimental data of the present study are compared to results of other authors and discrepancies discussed in detail. PMID:14550885

  14. Hydrolysis of chlorantraniliprole and cyantraniliprole in various pH buffer solutions.

    PubMed

    Sharma, Ashok K; Zimmerman, William T; Lowrie, Chris; Chapleo, Simon

    2014-04-23

    The hydrolysis reactions of [(14)C]-chlorantraniliprole (CLAP) and cyantraniliprole (CNAP) were investigated in sterile buffer solutions at pH 4, 7, and 9. Both compounds displayed similar degradation reactions. The reactions observed were intramolecular cyclizations and rearrangements instead of the anticipated amide hydrolysis to carboxylic acids. Despite a minor difference in their structures, the degradation rates for the two compounds were substantially different. The reaction rates were examined at multiple temperatures to understand the mechanistic aspects of the underlying transformations. Similarities and differences in the hydrolysis behavior of these compounds in various pH values and temperatures are described. PMID:24694259

  15. D-buffer: irregular image data storage made practical

    NASA Astrophysics Data System (ADS)

    Lipowski, J. K.

    2013-03-01

    Modern hardware accelerated graphics pipelines are designed to operate on data in a so called streaming model. To process the data in this model one needs to impose some restrictions on input and output argument's (most frequently represented by a two-dimensional frame buffer) memory structure. The output data regularity is obvious when we consider rasterizing hardware architecture, which draws 3D polygons using depth buffer to resolve the visible surface problem. But recently the user's needs surpass those restrictions with increasing frequency. In this work we formulate and present new methods of irregular frame buffer storage and ordering. The so called deque buffer (or D-buffer) allows us to decrease the amount of memory used for storage as well as the memory latency cost by using pixel data ordering. Our findings are confirmed by experimental results that measure the processing time, which is up to four times shorter, when compared with previous work by other authors. We also include a detailed description of algorithms used for D-buffer construction on the last three consumer-grade graphics hardware architectures, as a guide for other researchers and a development aid for practitioners. The only theoretical requirement imposed by our method is the use of memory model with linear address space.

  16. DNA and buffers: the hidden danger of complex formation.

    PubMed

    Stellwagen, N C; Gelfi, C; Righetti, P G

    2000-08-01

    The free solution electrophoretic mobility of DNA differs significantly in different buffers, suggesting that DNA-buffer interactions are present in certain buffer systems. Here, capillary and gel electrophoresis data are combined to show that the Tris ions in Tris-acetate-EDTA (TAE) buffers are associated with the DNA helix to approximately the same extent as sodium ions. The borate ions in Tris-borate-EDTA (TBE) buffers interact with DNA to form highly charged DNA-borate complexes, which are stable both in free solution and in polyacrylamide gels. DNA-borate complexes are not observed in agarose gels, because of the competition of the agarose gel fibers for the borate residues. The resulting agarose-borate complexes increase the negative charge of the agarose gel fibers, leading to an increased electroendosmotic flow of the solvent in agarose-TBE gels. The combined results indicate that the buffers in which DNA is studied cannot automatically be assumed to be innocuous. PMID:10861374

  17. Macrophyte and pH buffering updates to the Klamath River water-quality model upstream of Keno Dam, Oregon

    USGS Publications Warehouse

    Sullivan, Annett B.; Rounds, Stewart A.; Asbill-Case, Jessica R.; Deas, Michael L.

    2013-01-01

    A hydrodynamic, water temperature, and water-quality model of the Link River to Keno Dam reach of the upper Klamath River was updated to account for macrophytes and enhanced pH buffering from dissolved organic matter, ammonia, and orthophosphorus. Macrophytes had been observed in this reach by field personnel, so macrophyte field data were collected in summer and fall (June-October) 2011 to provide a dataset to guide the inclusion of macrophytes in the model. Three types of macrophytes were most common: pondweed (Potamogeton species), coontail (Ceratophyllum demersum), and common waterweed (Elodea canadensis). Pondweed was found throughout the Link River to Keno Dam reach in early summer with densities declining by mid-summer and fall. Coontail and common waterweed were more common in the lower reach near Keno Dam and were at highest density in summer. All species were most dense in shallow water (less than 2 meters deep) near shore. The highest estimated dry weight biomass for any sample during the study was 202 grams per square meter for coontail in August. Guided by field results, three macrophyte groups were incorporated into the CE-QUAL-W2 model for calendar years 2006-09. The CE-QUAL-W2 model code was adjusted to allow the user to initialize macrophyte populations spatially across the model grid. The default CE-QUAL-W2 model includes pH buffering by carbonates, but does not include pH buffering by organic matter, ammonia, or orthophosphorus. These three constituents, especially dissolved organic matter, are present in the upper Klamath River at concentrations that provide substantial pH buffering capacity. In this study, CE-QUAL-W2 was updated to include this enhanced buffering capacity in the simulation of pH. Acid dissociation constants for ammonium and phosphoric acid were taken from the literature. For dissolved organic matter, the number of organic acid groups and each group's acid dissociation constant (Ka) and site density (moles of sites per mole of

  18. Scaling carbon and nitrogen interactions. What are the consequences of biological buffering?

    SciTech Connect

    Weston, David; Rogers, Alistair; Tschaplinski, Timothy J.; Gunter, Lee E; Jawdy, Sara; Engle, Nancy L.; Heady, Lindsey E.; Tuskan, Gerald A.; Wullschleger, Stan D.

    2015-06-25

    Understanding the consequences of elevated CO2 (eCO2; 800 ppm) on terrestrial ecosystems is a central theme in global change biology, but relatively little is known about how altered plant C and N metabolism influences higher levels of biological organization. Here, we investigate the consequences of C and N interactions by genetically modifying the N-assimilation pathway in Arabidopsis and initiating growth chamber and mesocosm competition studies at current CO2 (cCO2; 400 ppm) and eCO2 over multiple generations. Using a suite of ecological, physiological, and molecular genomic tools, we show that a single-gene mutant of a key enzyme (nia2) elicited a highly orchestrated buffering response starting with a fivefold increase in the expression of a gene paralog (nia1) and a 63% increase in the expression of gene network module enriched for N-assimilation genes. The genetic perturbation reduced amino acids, protein, and TCA-cycle intermediate concentrations in the nia2 mutant compared to the wild-type, while eCO2 mainly increased carbohydrate concentrations. The mutant had reduced net photosynthetic rates due to a 27% decrease in carboxylation capacity and an 18% decrease in electron transport rates. The expression of these buffering mechanisms resulted in a penalty that negatively correlated with fitness and population dynamics yet showed only minor alterations in our estimates of population function, including total per unit area biomass, ground cover, and leaf area index. This study provides insight into the consequences of buffering mechanisms that occur post-genetic perturbations in the N pathway and the associated outcomes these buffering systems have on plant populations relative to eCO2.

  19. Scaling carbon and nitrogen interactions. What are the consequences of biological buffering?

    DOE PAGESBeta

    Weston, David; Rogers, Alistair; Tschaplinski, Timothy J.; Gunter, Lee E; Jawdy, Sara; Engle, Nancy L.; Heady, Lindsey E.; Tuskan, Gerald A.; Wullschleger, Stan D.

    2015-06-25

    Understanding the consequences of elevated CO2 (eCO2; 800 ppm) on terrestrial ecosystems is a central theme in global change biology, but relatively little is known about how altered plant C and N metabolism influences higher levels of biological organization. Here, we investigate the consequences of C and N interactions by genetically modifying the N-assimilation pathway in Arabidopsis and initiating growth chamber and mesocosm competition studies at current CO2 (cCO2; 400 ppm) and eCO2 over multiple generations. Using a suite of ecological, physiological, and molecular genomic tools, we show that a single-gene mutant of a key enzyme (nia2) elicited a highlymore » orchestrated buffering response starting with a fivefold increase in the expression of a gene paralog (nia1) and a 63% increase in the expression of gene network module enriched for N-assimilation genes. The genetic perturbation reduced amino acids, protein, and TCA-cycle intermediate concentrations in the nia2 mutant compared to the wild-type, while eCO2 mainly increased carbohydrate concentrations. The mutant had reduced net photosynthetic rates due to a 27% decrease in carboxylation capacity and an 18% decrease in electron transport rates. The expression of these buffering mechanisms resulted in a penalty that negatively correlated with fitness and population dynamics yet showed only minor alterations in our estimates of population function, including total per unit area biomass, ground cover, and leaf area index. This study provides insight into the consequences of buffering mechanisms that occur post-genetic perturbations in the N pathway and the associated outcomes these buffering systems have on plant populations relative to eCO2.« less

  20. Scaling nitrogen and carbon interactions: what are the consequences of biological buffering?

    PubMed

    Weston, David J; Rogers, Alistair; Tschaplinski, Timothy J; Gunter, Lee E; Jawdy, Sara A; Engle, Nancy L; Heady, Lindsey E; Tuskan, Gerald A; Wullschleger, Stan D

    2015-07-01

    Understanding the consequences of elevated CO2 (eCO2; 800 ppm) on terrestrial ecosystems is a central theme in global change biology, but relatively little is known about how altered plant C and N metabolism influences higher levels of biological organization. Here, we investigate the consequences of C and N interactions by genetically modifying the N-assimilation pathway in Arabidopsis and initiating growth chamber and mesocosm competition studies at current CO2 (cCO2; 400 ppm) and eCO2 over multiple generations. Using a suite of ecological, physiological, and molecular genomic tools, we show that a single-gene mutant of a key enzyme (nia2) elicited a highly orchestrated buffering response starting with a fivefold increase in the expression of a gene paralog (nia1) and a 63% increase in the expression of gene network module enriched for N-assimilation genes. The genetic perturbation reduced amino acids, protein, and TCA-cycle intermediate concentrations in the nia2 mutant compared to the wild-type, while eCO2 mainly increased carbohydrate concentrations. The mutant had reduced net photosynthetic rates due to a 27% decrease in carboxylation capacity and an 18% decrease in electron transport rates. The expression of these buffering mechanisms resulted in a penalty that negatively correlated with fitness and population dynamics yet showed only minor alterations in our estimates of population function, including total per unit area biomass, ground cover, and leaf area index. This study provides insight into the consequences of buffering mechanisms that occur post-genetic perturbations in the N pathway and the associated outcomes these buffering systems have on plant populations relative to eCO2. PMID:26306170

  1. Scaling nitrogen and carbon interactions: what are the consequences of biological buffering?

    PubMed Central

    Weston, David J; Rogers, Alistair; Tschaplinski, Timothy J; Gunter, Lee E; Jawdy, Sara A; Engle, Nancy L; Heady, Lindsey E; Tuskan, Gerald A; Wullschleger, Stan D

    2015-01-01

    Understanding the consequences of elevated CO2 (eCO2; 800 ppm) on terrestrial ecosystems is a central theme in global change biology, but relatively little is known about how altered plant C and N metabolism influences higher levels of biological organization. Here, we investigate the consequences of C and N interactions by genetically modifying the N-assimilation pathway in Arabidopsis and initiating growth chamber and mesocosm competition studies at current CO2 (cCO2; 400 ppm) and eCO2 over multiple generations. Using a suite of ecological, physiological, and molecular genomic tools, we show that a single-gene mutant of a key enzyme (nia2) elicited a highly orchestrated buffering response starting with a fivefold increase in the expression of a gene paralog (nia1) and a 63% increase in the expression of gene network module enriched for N-assimilation genes. The genetic perturbation reduced amino acids, protein, and TCA-cycle intermediate concentrations in the nia2 mutant compared to the wild-type, while eCO2 mainly increased carbohydrate concentrations. The mutant had reduced net photosynthetic rates due to a 27% decrease in carboxylation capacity and an 18% decrease in electron transport rates. The expression of these buffering mechanisms resulted in a penalty that negatively correlated with fitness and population dynamics yet showed only minor alterations in our estimates of population function, including total per unit area biomass, ground cover, and leaf area index. This study provides insight into the consequences of buffering mechanisms that occur post-genetic perturbations in the N pathway and the associated outcomes these buffering systems have on plant populations relative to eCO2. PMID:26306170

  2. Good’s buffers as a basis for developing self-buffering and biocompatible ionic liquids for biological research†

    PubMed Central

    Taha, Mohamed; e Silva, Francisca A.; Quental, Maria V.; Ventura, Sónia P. M.; Freire, Mara G.; Coutinho, João A. P.

    2014-01-01

    This work reports a promising approach to the development of novel self-buffering and biocompatible ionic liquids for biological research in which the anions are derived from biological buffers (Good’s buffers, GB). Five Good’s buffers (Tricine, TES, CHES, HEPES, and MES) were neutralized with four suitable hydroxide bases (1-ethyl-3-methylimidazolium, tetramethylammonium, tetraethylammonium, and tetrabutylammonium) producing 20 Good’s buffer ionic liquids (GB-ILs). The presence of the buffering action of the synthesized GB-ILs was ascertained by measuring their pH-profiles in water. Moreover, a series of mixed GB-ILs with wide buffering ranges were formulated as universal buffers. The impact of GB-ILs on bovine serum albumin (BSA), here used as a model protein, is discussed and compared with more conventional ILs using spectroscopic techniques, such as infrared and dynamic light scattering. They appear to display, in general, a greater stabilizing effect on the protein secondary structure than conventional ILs. A molecular docking study was also carried out to investigate on the binding sites of GB-IL ions to BSA. We further used the QSAR-human serum albumin binding model, log K(HSA), to calculate the binding affinity of some conventional ILs/GB-ILs to HSA. The toxicity of the GB and GB-ILs was additionally evaluated revealing that they are non-toxic against Vitro fischeri. Finally, the GB-ILs were also shown to be able to form aqueous biphasic systems when combined with aqueous solutions of inorganic or organic salts, and we tested their extraction capability for BSA. These systems were able to extract BSA with an outstanding extraction efficiency of 100% in a single step for the GB-IL-rich phase, and, as a result, the use of GB-IL-based ABS for the separation and extraction of other added-value biomolecules is highly encouraging and worthy of further investigation. PMID:25729325

  3. The Effect of Crystallizing and Non-crystallizing Cosolutes on Succinate Buffer Crystallization and the Consequent pH Shift in Frozen Solutions

    SciTech Connect

    Sundaramurthi, Prakash; Suryanarayanan, Raj

    2011-09-06

    To effectively inhibit succinate buffer crystallization and the consequent pH changes in frozen solutions. Using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD), the crystallization behavior of succinate buffer in the presence of either (i) a crystallizing (glycine, mannitol, trehalose) or (ii) a non-crystallizing cosolute (sucrose) was evaluated. Aqueous succinate buffer solutions, 50 or 200 mM, at pH values 4.0 or 6.0 were cooled from room temperature to -25 C at 0.5 C/min. The pH of the solution was measured as a function of temperature using a probe designed to function at low temperatures. The final lyophiles prepared from these solutions were characterized using synchrotron radiation. When the succinic acid solution buffered to pH 4.0, in the absence of a cosolute, was cooled, there was a pronounced shift in the freeze-concentrate pH. Glycine and mannitol, which have a tendency to crystallize in frozen solutions, remained amorphous when the initial pH was 6.0. Under this condition, they also inhibited buffer crystallization and prevented pH change. At pH 4.0 (50 mM initial concentration), glycine and mannitol crystallized and did not prevent pH change in frozen solutions. While sucrose, a non-crystallizing cosolute, did not completely prevent buffer crystallization, the extent of crystallization was reduced. Sucrose decomposition, based on XRD peaks attributable to {beta}-D-glucose, was observed in frozen buffer solutions with an initial pH of 4.0. Trehalose completely inhibited crystallization of the buffer components when the initial pH was 6.0 but not at pH 4.0. At the lower pH, the crystallization of both trehalose dihydrate and buffer components was evident. When retained amorphous, sucrose and trehalose effectively inhibited succinate buffer component crystallization and the consequent pH shift. However, when trehalose crystallized or sucrose degraded to yield a crystalline decomposition product, crystallization of buffer was

  4. Diversity of the lactic acid bacterium and yeast microbiota in the switch from firm- to liquid-sourdough fermentation.

    PubMed

    Di Cagno, Raffaella; Pontonio, Erica; Buchin, Solange; De Angelis, Maria; Lattanzi, Anna; Valerio, Francesca; Gobbetti, Marco; Calasso, Maria

    2014-05-01

    Four traditional type I sourdoughs were comparatively propagated (28 days) under firm (dough yield, 160) and liquid (dough yield, 280) conditions to mimic the alternative technology options frequently used for making baked goods. After 28 days of propagation, liquid sourdoughs had the lowest pH and total titratable acidity (TTA), the lowest concentrations of lactic and acetic acids and free amino acids, and the most stable density of presumptive lactic acid bacteria. The cell density of yeasts was the highest in liquid sourdoughs. Liquid sourdoughs showed simplified microbial diversity and harbored a low number of strains, which were persistent. Lactobacillus plantarum dominated firm sourdoughs over time. Leuconostoc lactis and Lactobacillus brevis dominated only some firm sourdoughs, and Lactobacillus sanfranciscensis persisted for some time only in some firm sourdoughs. Leuconostoc citreum persisted in all firm and liquid sourdoughs, and it was the only species detected in liquid sourdoughs at all times; it was flanked by Leuconostoc mesenteroides in some sourdoughs. Saccharomyces cerevisiae, Candida humilis, Saccharomyces servazzii, Saccharomyces bayanus-Kazachstania sp., and Torulaspora delbrueckii were variously identified in firm and liquid sourdoughs. A total of 197 volatile components were identified through purge and trap-/solid-phase microextraction-gas chromatography-mass spectrometry (PT-/SPME-GC-MS). Aldehydes, several alcohols, and some esters were at the highest levels in liquid sourdoughs. Firm sourdoughs mainly contained ethyl acetate, acetic acid, some sulfur compounds, and terpenes. The use of liquid fermentation would change the main microbial and biochemical features of traditional baked goods, which have been manufactured under firm conditions for a long time. PMID:24632249

  5. Diversity of the Lactic Acid Bacterium and Yeast Microbiota in the Switch from Firm- to Liquid-Sourdough Fermentation

    PubMed Central

    Di Cagno, Raffaella; Pontonio, Erica; Buchin, Solange; De Angelis, Maria; Lattanzi, Anna; Valerio, Francesca; Calasso, Maria

    2014-01-01

    Four traditional type I sourdoughs were comparatively propagated (28 days) under firm (dough yield, 160) and liquid (dough yield, 280) conditions to mimic the alternative technology options frequently used for making baked goods. After 28 days of propagation, liquid sourdoughs had the lowest pH and total titratable acidity (TTA), the lowest concentrations of lactic and acetic acids and free amino acids, and the most stable density of presumptive lactic acid bacteria. The cell density of yeasts was the highest in liquid sourdoughs. Liquid sourdoughs showed simplified microbial diversity and harbored a low number of strains, which were persistent. Lactobacillus plantarum dominated firm sourdoughs over time. Leuconostoc lactis and Lactobacillus brevis dominated only some firm sourdoughs, and Lactobacillus sanfranciscensis persisted for some time only in some firm sourdoughs. Leuconostoc citreum persisted in all firm and liquid sourdoughs, and it was the only species detected in liquid sourdoughs at all times; it was flanked by Leuconostoc mesenteroides in some sourdoughs. Saccharomyces cerevisiae, Candida humilis, Saccharomyces servazzii, Saccharomyces bayanus-Kazachstania sp., and Torulaspora delbrueckii were variously identified in firm and liquid sourdoughs. A total of 197 volatile components were identified through purge and trap–/solid-phase microextraction–gas chromatography-mass spectrometry (PT–/SPME–GC-MS). Aldehydes, several alcohols, and some esters were at the highest levels in liquid sourdoughs. Firm sourdoughs mainly contained ethyl acetate, acetic acid, some sulfur compounds, and terpenes. The use of liquid fermentation would change the main microbial and biochemical features of traditional baked goods, which have been manufactured under firm conditions for a long time. PMID:24632249

  6. Inactivation of viruses using novel protein A wash buffers.

    PubMed

    Bolton, Glen R; Selvitelli, Keith R; Iliescu, Ionela; Cecchini, Douglas J

    2015-01-01

    Low pH viral inactivation is typically performed in the eluate pool following the protein A capture step during the manufacturing of monoclonal antibodies and Fc-fusion proteins. However, exposure to low pH has the potential to alter protein quality. To avoid these difficulties, novel wash buffers capable of inactivating viruses while antibodies or Fc-fusion proteins were bound to protein A or mixed mode resins were developed. By equilibrating the column in high salt buffer (2 M ammonium sulfate or 3 M sodium chloride) after loading, the hydrophobic interactions between antibodies and protein A ligands were increased enough to prevent elution at pH 3. The ammonium sulfate was also found to cause binding of an antibody to a mixed mode cation exchange and a mixed mode anion exchange resin at pH values that caused elution in conventional cation and anion exchange resins (pH 3.5 for Capto Adhere and pH 8.0 for Capto MMC), indicating that retention was due to enhanced hydrophobic interactions. The potential of the 2 M ammonium sulfate pH 3 buffer, a 1 M arginine buffer, and a buffer containing the detergent LDAO to inactivate XMuLV virus when used as protein A wash buffers with a 1 hour contact time were studied. The high salt and detergent containing wash buffers provided about five logs of removal, determined using PCR, and complete combined removal and inactivation (> 6 logs), determined by measuring infectivity. The novel protein A washes could provide more rapid, automated viral inactivation steps with lower pool conductivities. PMID:25482293

  7. Assessing multiregion avian benefits from strategically targeted agricultural buffers.

    PubMed

    Evans, Kristine O; Burger, L Wes; Riffell, Sam; Smith, Mark D

    2014-08-01

    Mounting evidence of wildlife population gains from targeted conservation practices has prompted the need to develop and evaluate practices that are integrated into production agriculture systems and targeted toward specific habitat objectives. However, effectiveness of targeted conservation actions across broader landscapes is poorly understood. We evaluated multiregion, multispecies avian densities on row-crop fields with native grass field margins (i.e., buffers) as part of the first U.S. agricultural conservation practice designed to support habitat and population recovery objectives of a national wildlife conservation initiative. We coordinated breeding season point transect surveys for 6 grassland bird species on 1151 row-crop fields with and without native grass buffers (9-37 m) in 14 U.S. states (10 ecoregions) from 2006 to 2011. In most regions, breeding season densities of 5 of 6 targeted bird species were greater in the 500-m surrounding survey points centered on fields with native grass buffers than in landscapes without buffers. Relative effect sizes were greatest for Northern Bobwhite (Colinus virginianus), Dickcissel (Spiza americana), and Field Sparrow (Spizella pusilla) in the Mississippi Alluvial Valley and Eastern Tallgrass Prairie regions. Other species (e.g., Eastern Meadowlark [Sturnella magna], Grasshopper Sparrow [Ammodramus savannarum]) exhibited inconsistent relative effect sizes. Bird densities on fields with and without buffers were greatest in the Central Mixed-grass Prairie region. Our results suggest that strategic use of conservation buffers in regions with the greatest potential for relative density increases in target species will elicit greater range-wide population response than diffuse, uninformed, and broadly distributed implementation of buffers. We recommend integrating multiple conservation practices in broader agricultural landscapes to maximize conservation effectiveness for a larger suite of species. PMID:24779636

  8. CHEMICAL SOLUTION DEPOSITION BASED OXIDE BUFFERS AND YBCO COATED CONDUCTORS

    SciTech Connect

    Paranthaman, Mariappan Parans

    2011-01-01

    We have reviewed briefly the growth of buffer and high temperature superconducting oxide thin films using a chemical solution deposition (CSD) method. In the Rolling-Assisted Biaxially Textured Substrates (RABiTS) process, developed at Oak Ridge National Laboratory, utilizes the thermo mechanical processing to obtain the flexible, biaxially oriented copper, nickel or nickel-alloy substrates. Buffers and Rare Earth Barium Copper Oxide (REBCO) superconductors have been deposited epitaxially on the textured nickel alloy substrates. The starting substrate serves as a template for the REBCO layer, which has substantially fewer weak links. Buffer layers play a major role in fabricating the second generation REBCO wire technology. The main purpose of the buffer layers is to provide a smooth, continuous and chemically inert surface for the growth of the REBCO film, while transferring the texture from the substrate to the superconductor layer. To achieve this, the buffer layers need to be epitaxial to the substrate, i.e. they have to nucleate and grow in the same bi-axial texture provided by the textured metal foil. The most commonly used RABiTS multi-layer architectures consist of a starting template of biaxially textured Ni-5 at.% W (Ni-W) substrate with a seed (first) layer of Yttrium Oxide (Y2O3), a barrier (second) layer of Yttria Stabilized Zirconia (YSZ), and a Cerium Oxide (CeO2) cap (third) layer. These three buffer layers are generally deposited using physical vapor deposition (PVD) techniques such as reactive sputtering. On top of the PVD template, REBCO film is then grown by a chemical solution deposition. This article reviews in detail about the list of oxide buffers and superconductor REBCO films grown epitaxially on single crystal and/or biaxially textured Ni-W substrates using a CSD method.

  9. Message communications of particular message types between compute nodes using DMA shadow buffers

    SciTech Connect

    Blocksome, Michael A.; Parker, Jeffrey J.

    2010-11-16

    Message communications of particular message types between compute nodes using DMA shadow buffers includes: receiving a buffer identifier specifying an application buffer having a message of a particular type for transmission to a target compute node through a network; selecting one of a plurality of shadow buffers for a DMA engine on the compute node for storing the message, each shadow buffer corresponding to a slot of an injection FIFO buffer maintained by the DMA engine; storing the message in the selected shadow buffer; creating a data descriptor for the message stored in the selected shadow buffer; injecting the data descriptor into the slot of the injection FIFO buffer corresponding to the selected shadow buffer; selecting the data descriptor from the injection FIFO buffer; and transmitting the message specified by the selected data descriptor through the data communications network to the target compute node.

  10. Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin

    NASA Astrophysics Data System (ADS)

    Hagens, M.; Slomp, C. P.; Meysman, F. J. R.; Seitaj, D.; Harlay, J.; Borges, A. V.; Middelburg, J. J.

    2015-03-01

    Coastal areas are impacted by multiple natural and anthropogenic processes and experience stronger pH fluctuations than the open ocean. These variations can weaken or intensify the ocean acidification signal induced by increasing atmospheric pCO2. The development of eutrophication-induced hypoxia intensifies coastal acidification, since the CO2 produced during respiration decreases the buffering capacity in any hypoxic bottom water. To assess the combined ecosystem impacts of acidification and hypoxia, we quantified the seasonal variation in pH and oxygen dynamics in the water column of a seasonally stratified coastal basin (Lake Grevelingen, the Netherlands). Monthly water-column chemistry measurements were complemented with estimates of primary production and respiration using O2 light-dark incubations, in addition to sediment-water fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TA). The resulting data set was used to set up a proton budget on a seasonal scale. Temperature-induced seasonal stratification combined with a high community respiration was responsible for the depletion of oxygen in the bottom water in summer. The surface water showed strong seasonal variation in process rates (primary production, CO2 air-sea exchange), but relatively small seasonal pH fluctuations (0.46 units on the total hydrogen ion scale). In contrast, the bottom water showed less seasonality in biogeochemical rates (respiration, sediment-water exchange), but stronger pH fluctuations (0.60 units). This marked difference in pH dynamics could be attributed to a substantial reduction in the acid-base buffering capacity of the hypoxic bottom water in the summer period. Our results highlight the importance of acid-base buffering in the pH dynamics of coastal systems and illustrate the increasing vulnerability of hypoxic, CO2-rich waters to any acidifying process.

  11. Grass buffers for playas in agricultural landscapes: An annotated bibliography

    USGS Publications Warehouse

    Melcher, Cynthia P.; Skagen, Susan K.

    2005-01-01

    References on best management practices (BMPs) for agricultural lands were included because certain BMPs are crucial for informing decisions about buffer design/ effectiveness and overall playa ecology. We also included various papers that increase the spectrum of time over which buffer theories and practices have evolved. An unannotated section lists references that we did not prioritize for annotation and references that may be helpful but were beyond the scope of this document. Finally, we provide notes on conversations we had with scientists, land managers, and other buffer experts whom we consulted, and their contact information. We conclude the bibliography with appendices of common and scientific names of birds and plants and acronyms used in both the bibliography. In the annotations, italicized text signifies our own editorial remarks. Readers should also note that much of the work on buffers has been designed using English units of measure rather than metrics; in most cases, their results have been converted to metrics for publication, explaining the seemingly odd or irregular buffer widths and other parameters reported.

  12. Integrated optical buffers for packet-switched networks

    NASA Astrophysics Data System (ADS)

    Burmeister, Emily Frances

    Routers form the backbone of the Internet, directing data to the right locations with huge throughput capacity of terabits/second) and very few errors (1 error allowed in 1012 bits). However, as the Internet continues to grow rapidly, so must the capacity of electronic routers, thereby also growing in footprint and power consumption. The energy bill alone has developers looking for an alternate solution. Today's routers can only operate with electrical signals although Internet data is transmitted optically. This requires the data to be converted from the optical domain to the electrical domain and back again. Optical routers have the potential of saving in power by omitting these conversions, but have been held back in part by the lack of a practical optical memory device. This work presents the first integrated optical buffer for next generation optical packet-switched networks. Buffering is required in a router to move packets of data in order to avoid collisions between packets heading to the same destination at the same time. The device presented here uses an InP-based two-by-two switch with a silica waveguide delay to form a recirculating buffer. Packet storage was shown with 98% packet recovery for 5 circulations. Autonomous contention resolution was demonstrated with two buffered channels to show that the technology is a realistic solution for creating multiple element buffers on multiple router ports. This thesis proposes and demonstrates the first integrated optical random access memory, thereby making a great stride toward high capacity optical routers.

  13. Electrodialytic membrane suppressors for ion chromatography make programmable buffer generators.

    PubMed

    Chen, Yongjing; Srinivasan, Kannan; Dasgupta, Purnendu K

    2012-01-01

    The use of buffer solutions is immensely important in a great variety of disciplines. The generation of continuous pH gradients in flow systems plays an important role in the chromatographic separation of proteins, high-throughput pK(a) determinations, etc. We demonstrate here that electrodialytic membrane suppressors used in ion chromatography can be used to generate buffers. The generated pH, computed from first principles, agrees well with measured values. We demonstrate the generation of phosphate and citrate buffers using a cation-exchange membrane (CEM) -based anion suppressor and Tris and ethylenediamine buffers using an anion-exchange membrane (AEM) -based cation suppressor. Using a mixture of phosphate, citrate, and borate as the buffering ions and using a CEM suppressor, we demonstrate the generation of a highly reproducible (avg RSD 0.20%, n = 3), temporally linear (pH 3.0-11.9, r(2) > 0.9996), electrically controlled pH gradient. With butylamine and a large concentration (0.5 M) of added NaCl, we demonstrate a similar linear pH gradient of large range with a near-constant ionic strength. We believe that this approach will be of value for the generation of eluents in the separation of proteins and other biomolecules and in online process titrations. PMID:22103670

  14. RNA chaperones buffer deleterious mutations in E. coli

    PubMed Central

    Rudan, Marina; Schneider, Dominique; Warnecke, Tobias; Krisko, Anita

    2015-01-01

    Both proteins and RNAs can misfold into non-functional conformations. Protein chaperones promote native folding of nascent polypeptides and refolding of misfolded species, thereby buffering mutations that compromise protein structure and function. Here, we show that RNA chaperones can also act as mutation buffers that enhance organismal fitness. Using competition assays, we demonstrate that overexpression of select RNA chaperones, including three DEAD box RNA helicases (DBRHs) (CsdA, SrmB, RhlB) and the cold shock protein CspA, improves fitness of two independently evolved Escherichia coli mutator strains that have accumulated deleterious mutations during short- and long-term laboratory evolution. We identify strain-specific mutations that are deleterious and subject to buffering when introduced individually into the ancestral genotype. For DBRHs, we show that buffering requires helicase activity, implicating RNA structural remodelling in the buffering process. Our results suggest that RNA chaperones might play a fundamental role in RNA evolution and evolvability. DOI: http://dx.doi.org/10.7554/eLife.04745.001 PMID:25806682

  15. Effect of various commercial buffers on sperm viability and capacitation.

    PubMed

    Andrisani, Alessandra; Donà, Gabriella; Ambrosini, Guido; Bonanni, Guglielmo; Bragadin, Marcantonio; Cosmi, Erich; Clari, Giulio; Armanini, Decio; Bordin, Luciana

    2014-08-01

    A wide variety of sperm preparation protocols are currently available for assisted conception. They include density gradient separation and washing methods. Both aim at isolating and capacitating as much motile sperm as possible for subsequent oocyte fertilization. The aim of this study was to examine the effects of four commercial sperm washing buffers on sperm viability and capacitation. Semen samples from 48 healthy donors (normal values of sperm count, motility, morphology, and volume) were analyzed. After separation (density gradient 40/80%), sperm were incubated in various buffers then analysed for reactive oxygen species (ROS) production, viability, tyrosine phosphorylation (Tyr-P), cholera toxin B subunit (CTB) labeling, and the acrosome reaction (AR). The buffers affected ROS generation in various ways resulting either in rapid cell degeneration (when the amount of ROS was too high for cell survival) or the inability of the cells to maintain correct functioning (when ROS were too few). Only when the correct ROS generation curve was maintained, suitable membrane reorganization, evidenced by CTB labeling was achieved, leading to the highest percentages of both Tyr-P- and acrosome-reacted-cells. Distinguishing each particular pathological state of the sperm sample would be helpful to select the preferred buffer treatment since both ROS production and membrane reorganization can be significantly altered by commercial buffers. PMID:24673547

  16. Method of depositing buffer layers on biaxially textured metal substrates

    DOEpatents

    Beach, David B.; Morrell, Jonathan S.; Paranthaman, Mariappan; Chirayil, Thomas; Specht, Eliot D.; Goyal, Amit

    2002-08-27

    A laminate article comprises a substrate and a biaxially textured (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer over the substrate, wherein 0buffer layer can be deposited using sol-gel or metal-organic decomposition. The laminate article can include a layer of YBCO over the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (RE.sup.1.sub.x RE.sup.2.sub.(1-x)).sub.2 O.sub.3 buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  17. Lot A2 test, THC modelling of the bentonite buffer

    NASA Astrophysics Data System (ADS)

    Itälä, Aku; Olin, Markus; Lehikoinen, Jarmo

    Finnish spent nuclear fuel is planned to be disposed of deep in the crystalline bedrock of the Olkiluoto island. In such a repository, the role of the bentonite buffer is considered to be central. The initially unsaturated bentonite emplaced around a spent-fuel canister will become fully saturated by the groundwater from the host rock. In order to assess the long-term safety of a deep repository, it is essential to determine how temperature influences the chemical stability of bentonite. The aim of this study was to achieve an improved understanding of the factors governing the thermo-hydro-chemical evolution of the bentonite buffer subject to heat generation from the disposed fuel and in contact with a highly permeable rock fracture intersecting a canister deposition hole. TOUGHREACT was used to model a test known as the long-term test of buffer material adverse-2, which was conducted at the Äspö hard rock laboratory in Sweden. The results on the evolution of cation-exchange equilibria, bentonite porewater chemistry, mineralogy, and saturation of the buffer are presented and discussed. The calculated model results show similarity to the experimental results. In particular, the spatial differences in the saturation and porewater chemistry of the bentonite buffer were clearly visible in the model.

  18. Rare earth zirconium oxide buffer layers on metal substrates

    DOEpatents

    Williams, Robert K.; Paranthaman, Mariappan; Chirayil, Thomas G.; Lee, Dominic F.; Goyal, Amit; Feenstra, Roeland

    2001-01-01

    A laminate article comprises a substrate and a biaxially textured (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer over the substrate, wherein 0buffer layer can be deposited using sol-gel or metal-organic decomposition. The laminate article can include a layer of YBCO over the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  19. Comparison of the effect of different pH buffering techniques on the toxicity of copper and zinc to Daphnia magna and Pseudokirchneriella subcapitata.

    PubMed

    De Schamphelaere, K A C; Heijerick, D G; Janssen, C R

    2004-10-01

    During the time-course of ecotoxicity tests with algae and chronic (reproductive) toxicity tests with daphnids, in which algae are present as a food source, pH can dramatically increase due to photosynthetic activity. As pH changes can significantly affect metal speciation and thus its bioavailability, it may be necessary to buffer the pH of the exposure medium. One class of buffers (Good's N-subtituted aminosulfonic acids) are increasingly being used in biological and chemical applications, including ecotoxicity testing. However, the potential effect of these buffers on metal toxicity has, so far, scarcely been examined. In this study we investigated if MOPS (3-N morpholino propane sulfonic acid) affected the toxicity of copper and zinc to two standard test organisms: the cladoceran Daphnia magna and the green alga Pseudokirchneriella subcapitata. First, we demonstrate that up to a concentration of 750 mg l(-1) (which proved to be sufficient for pH buffering) MOPS did not affect 21-day net reproduction of D. magna or the 72-h population growth of P. subcapitata. Second, we conducted bioassays in copper and zinc spiked standard media for the pH range 6-8. For D. magna the possible effect of 750 mg l(-1) MOPS on acute copper and zinc toxicity was investigated by performing parallel 48-h toxicity tests in NaHCO3 and MOPS buffered test media. Seventy-two hour growth inhibition assays with P. subcapitata were performed in parallel in MOPS and NaHCO3 buffered test media and in test media with daily manual pH adjustment with HCl. For daphnids no significant differences in copper and zinc toxicity were observed between MOPS or NaHCO3 buffered test media. For algae no significant differences in metal toxicity were observed between MOPS and HCl buffered media, but in test media buffered with NaHCO3 an increased copper and zinc toxicity was observed as a consequence of pH increases during the test. Clearly, the results of this study demonstrate the importance of pH buffering

  20. Structure, Optical Absorption, and Performance of Organic Solar Cells Improved by Gold Nanoparticles in Buffer Layers.

    PubMed

    Yang, Yingguo; Feng, Shanglei; Li, Meng; Wu, Zhongwei; Fang, Xiao; Wang, Fei; Geng, Dongping; Yang, Tieying; Li, Xiaolong; Sun, Baoquan; Gao, Xingyu

    2015-11-11

    11-Mercaptoundecanoic acid (MUA)-stabilized gold nanoparticles (AuNPs) embedded in copper phthalocyanine (CuPc) were used as a buffer layer between a poly(3-hexyl-thiophene) (P3HT)/[6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction and anodic indium-tin oxide (ITO) substrate. As systematic synchrotron-based grazing incidence X-ray diffraction (GIXRD) experiments demonstrated that the AuNPs present in the buffer layer can improve the microstructure of the active layer with a better lamella packing of P3HT from the surface to the interior, UV-visible absorption spectrum measurements revealed enhanced optical absorption due to the localized surface plasma resonance (LSPR) generated by the AuNPs. The device of ITO/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate/CuPc:MUA-stabilized AuNPs/P3HT:PCBM/LiF/Al was found with over 24% enhancement of power conversion efficiency (PCE) in comparison with reference devices without AuNPs. This remarkable improvement in PCE should be partially attributed to LSPR generated by the AuNPs and partially to improved crystallization as well as preferred orientation order of P3HT due to the presence of the AuNPs, which would promote more applications of metal NPs in the organic photovoltaic devices and other organic multilayer devices. PMID:26477556

  1. Retention of ionisable compounds on high-performance liquid chromatography. XV. Estimation of the pH variation of aqueous buffers with the change of the acetonitrile fraction of the mobile phase.

    PubMed

    Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

    2004-12-01

    The most commonly used mobile phases in reversed-phase high-performance liquid chromatography (RP-HPLC) are hydro-organic mixtures of an aqueous buffer and an organic modifier. The addition of this organic solvent to buffered aqueous solutions involves a variation of the buffer properties (pH and buffer capacity). In this paper, the pH variation is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-citrate, and ammonium-ammonia buffers. The proposed equations allow pH estimation of acetonitrile-water buffered mobile phases up to 60% (v/v) of organic modifier and initial aqueous buffer concentrations between 0.001 and 0.1 mol L(-1), from the initial aqueous pH. The estimated pH variation of the mobile phase and the pKa variation of the analytes allow us to predict the degree of ionisation of the analytes and from this and analyte hydrophobicities, to interpret the relative retention and separation of analyte mixtures. PMID:15628122

  2. Basics of base in hemodialysis solution: Dialysate buffer production, delivery and decontamination

    PubMed Central

    Desai, N.

    2015-01-01

    Hemodialysis requires the use of high volumes of freshly prepared, clean dialysate to foster the removal of low molecular weight metabolites (i.e., urea) and to correct the electrolyte and acid-base imbalance of chronic renal failure. Dialysate is produced by mixing clean, AAMI grade water with both an acid and base concentrate. This purpose of this report is to describe production, mixing and delivery of the buffer component of dialysate, and to also to address the cost, safety and feasibility of producing online bicarbonate. As endotoxin contaminated dialysate has been associated with the release of key mediators in acute and chronic inflammatory diseases associated with long-term hemodialysis therapy, aspects of disinfecting a bicarbonate delivery loop are also addressed. PMID:26199467

  3. Systematic designs of buffers in macropipelines of systolic arrays

    SciTech Connect

    Wah, B.W.; Aboelaze, M.; Shang, W.

    1988-02-01

    In a macropipeline of systolic arrays, outputs of one systolic array in a given format have to be fed as inputs to another systolic array in a possibly different format. A common memory becomes a bottleneck and limits the number of systolic arrays that can be connected together. In this paper, they study designs of buffers to convert data from one format to another. The minimum number of buffers is determined by a dynamic-programming algorithm with THETA(n/sup 2/) computational complexity, where n is the problem size. A general-purpose converter to convert data from any distribution to any other in a subset of the possible data distribution is also proposed. Last, buffer designs for a macropipeline to perform feature extraction and pattern classification are used to exemplify the design process.

  4. Redox buffering in shallow aquifers contaminated by leachate

    SciTech Connect

    Heron, G.; Bjerg, P.L.; Christensen, T.H.

    1995-12-31

    The redox conditions in two Danish landfill leachate-polluted aquifers (the Vejen and Grindsted) are discussed in terms of redox buffering. Dominant leachate contributors to reduction capacity (RDC) are dissolved organic matter and ammonium. Aquifer oxidation capacity is dominated by Fe(III) oxides, and the Vejen Landfill case shows that redox buffering by reduction of Fe(III) oxides may be important for plume development. Inorganic precipitates such as pyrite and other Fe(II) minerals may dramatically increase the oxygen demand of the aquifer. In mineral-poor aquifers such as the lower aquifer at Grindsted Landfill, redox buffering by solid electron acceptors is far less important, and smaller quantities of reduced species are formed.

  5. A 20 MHz CMOS reorder buffer for a superscalar microprocessor

    NASA Technical Reports Server (NTRS)

    Lenell, John; Wallace, Steve; Bagherzadeh, Nader

    1992-01-01

    Superscalar processors can achieve increased performance by issuing instructions out-of-order from the original sequential instruction stream. Implementing an out-of-order instruction issue policy requires a hardware mechanism to prevent incorrectly executed instructions from updating register values. A reorder buffer can be used to allow a superscalar processor to issue instructions out-of-order and maintain program correctness. This paper describes the design and implementation of a 20MHz CMOS reorder buffer for superscalar processors. The reorder buffer is designed to accept and retire two instructions per cycle. A full-custom layout in 1.2 micron has been implemented, measuring 1.1058 mm by 1.3542 mm.

  6. Use of buffered hypochlorite solution for disinfecting fibrescopes.

    PubMed Central

    Coates, D; Death, J E

    1982-01-01

    The possible use of sodium hypochlorite solution buffered to pH 7.6 and containing 100 ppm available chlorine (avCl) for disinfecting fibrescopes was investigated. A flexible fibrescope experimentally contaminated with Pseudomonas putida, Mycobacterium fortuitum, or Bacillus subtilis spores was effectively disinfected within 10 m in repeatedly and without any observable adverse effect on the instrument. The corrosive nature of buffered hypochlorite was investigated by immersing various fibrescope components and metal wires in solutions of different strength for long periods and examining them for damage. Stainless steel, platinum, glass, Teflon, polythene and epoxy resin were apparently unaffected whereas polyurethane, rubber and other metals tested were damaged to different extents. Buffered hypochlorite solutions may have many applications pertaining to the disinfection of items which are either thermolabile or require rapid effective disinfection. PMID:6802880

  7. Optimization of buffer gas pressure for Rb atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Chen, Chang; Liu, Xiaohu; Qu, Tianliang; Yang, Kaiyong

    2015-08-01

    The optimization of buffer gas pressure is very important to improve the performance of the rubidium (Rb) atomic magnetometer. In this paper we briefly introduce the basic principle and the experimental method of the rubidium magnetometer based on Faraday rotation effect, and describe the factors affecting the magnetometer sensitivity, then analyze and summarize the mechanism of the influence of spin-exchange, spin-destruction collisions, radiation trapping and the spin diffusion on spin relaxation of Rb atoms. Based on this, the relationship between the rubidium magnetometer sensitivity, the spin relaxation rate and the gas chamber conditions (buffer gas pressure, the bubble radius, measuring temperature) is established. Doing calculations by the simulation software, how the magnetometer sensitivity and the relaxation rate vary with the gas chamber conditions can be seen; finally, the optimal values of the buffer gas pressure under certain gas chamber conditions are obtained. The work is significant for the engineering development of rubidium magnetometer.

  8. Buffer-gas effects on dark resonances: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Erhard, Michael; Helm, Hanspeter

    2001-04-01

    Dark resonances with widths below 30 Hz have been observed in a rubidium cell filled with neon as buffer gas at room temperature. We compare an approximate analytic solution of a Λ system to our data and show that under our experimental conditions the presence of the buffer gas reduces the power broadening of the dark resonances by two orders of magnitude. We also present numerical calculations that take into account the thermal motion and velocity-changing collisions with the buffer-gas atoms. The resulting dark-resonance features exhibit strong Dicke-type narrowing effects and thereby explain the elimination of Doppler shifts and Doppler broadening, leading to observation of a single ultranarrow dark line.

  9. Chemical chaperones assist intracellular folding to buffer mutational variations

    PubMed Central

    Bandyopadhyay, Anannya; Saxena, Kanika; Kasturia, Neha; Dalal, Vijit; Bhatt, Niraj; Rajkumar, Asher; Maity, Shuvadeep; Sengupta, Shantanu; Chakraborty, Kausik

    2012-01-01

    Hidden genetic variations harbor potential for the evolution of new traits. Molecular chaperones, that assist protein folding, may conceal genetic variations in protein coding regions. Here, we investigate if the chemical milieu of cells has the potential to alleviate intracellular protein folding; potentially implicating a role of osmolytes in concealing genetic variations. Using the model osmolyte TMAO, we uncover that it can buffer mutations that impose kinetic traps in the folding pathways of two model proteins. Using this information, we rationally designed TMAO-dependent mutants in vivo, starting from a TMAO-independent protein. Strikingly, we delineate different osmolytes to have a unique spectrum of buffered-mutations. Consequently, the chemical milieu of cells may alter the folding pathways of unique mutant variants in polymorphic populations and lead to unanticipated spectra of genetic buffering. PMID:22246401

  10. Buffer thermal energy storage for an air Brayton solar engine

    NASA Technical Reports Server (NTRS)

    Strumpf, H. J.; Barr, K. P.

    1981-01-01

    The application of latent-heat buffer thermal energy storage to a point-focusing solar receiver equipped with an air Brayton engine was studied. To demonstrate the effect of buffer thermal energy storage on engine operation, a computer program was written which models the recuperator, receiver, and thermal storage device as finite-element thermal masses. Actual operating or predicted performance data are used for all components, including the rotating equipment. Based on insolation input and a specified control scheme, the program predicts the Brayton engine operation, including flows, temperatures, and pressures for the various components, along with the engine output power. An economic parametric study indicates that the economic viability of buffer thermal energy storage is largely a function of the achievable engine life.

  11. Buffer layers on metal alloy substrates for superconducting tapes

    DOEpatents

    Jia, Quanxi; Foltyn, Stephen R.; Arendt, Paul N.; Groves, James R.

    2004-10-05

    An article including a substrate, at least one intermediate layer upon the surface of the substrate, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the at least one intermediate layer, and a layer of a SrRuO.sub.3 buffer material upon the oriented cubic oxide material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon the layer of a SrRuO.sub.3 buffer material layer. With a HTS top-layer of YBCO upon at least one layer of the SrRuO.sub.3 buffer material in such an article, J.sub.c 's of up to 1.3.times.10.sup.6 A/cm.sup.2 have been demonstrated with projected I.sub.c 's of over 200 Amperes across a sample 1 cm wide.

  12. Quantifying the capacity of compost buffers for treating agricultural runoff

    NASA Astrophysics Data System (ADS)

    Naranjo, S. A.; Beighley, R. E.; Buyuksonmez, F.

    2007-12-01

    Agricultural operations, specifically, avocado and commercial nurseries require frequent and significant fertilizing and irrigating which tends to result in excessive nutrient leaching and off-site runoff. The increased runoff contains high concentrations of nutrients which negatively impacts stream water quality. Researcher has demonstrated that best management practices such as compost buffers can be effective for reducing nutrient and sediment concentrations in agricultural runoff. The objective of this research is to evaluate both the hydraulic capacity and the nutrient removal efficiency of: (a) compost buffers and (b) buffers utilizing a combination of vegetation and compost. A series of experiments will be performed in the environmental hydraulics laboratory at San Diego State University. A tilting flume 12-m long, 27-cm wide and 25-cm deep will be used. Discharge is propelled by an axial flow pump powered by a variable speed motor with a maximum capacity of 30 liters per second. The experiments are designed to measure the ratio compost mass per flow rate per linear width. Two different discharges will be measured: (a) treatment discharge (maximum flow rate such that the buffer decreases the incoming nitrogen and phosphorus concentrations below a maximum allowable limit) and (b) breaking discharge (maximum flow rate the buffer can tolerate without structural failure). Experimental results are presented for the hydraulic analysis, and preliminary results are presented for the removal of nitrogen and phosphorus from runoff. The results from this project will be used to develop guidelines for installing compost buffers along the perimeters of nursery sites and avocado groves in southern California.

  13. Agroforestry buffers for nonpoint source pollution reductions from agricultural watersheds.

    PubMed

    Udawatta, Ranjith P; Garrett, Harold E; Kallenbach, Robert

    2011-01-01

    Despite increased attention and demand for the adoption of agroforestry practices throughout the world, rigorous long-term scientific studies confirming environmental benefits from the use of agroforestry practices are limited. The objective was to examine nonpoint-source pollution (NPSP) reduction as influenced by agroforestry buffers in watersheds under grazing and row crop management. The grazing study consists of six watersheds in the Central Mississippi Valley wooded slopes and the row crop study site consists of three watersheds in a paired watershed design in Central Claypan areas. Runoff water samples were analyzed for sediment, total nitrogen (TN), and total phosphorus (TP) for the 2004 to 2008 period. Results indicate that agroforestry and grass buffers on grazed and row crop management sites significantly reduce runoff, sediment, TN, and TP losses to streams. Buffers in association with grazing and row crop management reduced runoff by 49 and 19%, respectively, during the study period as compared with respective control treatments. Average sediment loss for grazing and row crop management systems was 13.8 and 17.9 kg ha yr, respectively. On average, grass and agroforestry buffers reduced sediment, TN, and TP losses by 32, 42, and 46% compared with the control treatments. Buffers were more effective in the grazing management practice than row crop management practice. These differences could in part be attributed to the differences in soils, management, and landscape features. Results from this study strongly indicate that agroforestry and grass buffers can be designed to improve water quality while minimizing the amount of land taken out of production. PMID:21546665

  14. Fifteenmile Creek Riparian Buffers Project, Annual Report 2002-2003.

    SciTech Connect

    Graves, Ron

    2004-02-01

    This project implements riparian buffer systems in the Mid-Columbia, addressing limiting factors identified in the Fifteenmile Subbasin Summary, June 30, 2000. The project is providing the technical planning support needed to implement at least 36 riparian buffer system contracts on approximately 872 acres covering an estimated 40 miles of anadromous fish streams over a three year period. During this second year of the project, 11 buffer contracts were implemented on 10.9 miles of stream. Buffer widths averaged 132 ft. on each side of the stream. Implementation included prescribed plantings, fencing, and related practices. Actual implementation costs, lease payments, and maintenance costs are borne by existing USDA programs: Conservation Reserve and Conservation Reserve Enhancement Programs. The lease period of each contract may vary between 10 to 15 years. During this year the average was 14.6 years. The total value of contracts established this year is $666,121 compared with $71,115 in Bonneville Power Administration (BPA) contract costs to provide the technical support needed to get the contracts implemented. This project provides technical staffing to conduct assessments and develop plans to help keep pace with the growing backlog of potential riparian buffer projects. Word of mouth from satisfied customers has brought in many new sign-ups during the year. In addition, specific outreach efforts targeting the orchard areas of the county began to bear fruit with orchardists sign-ups as the project year ended. Progress this second year of project includes only work accomplished in the Fifteenmile subbasin. A similar but separate effort to implement buffers in the Columbia Plateau Province was initiated during the year under project number 2002-019-00. This project supports RPA 150 and 153 as required under the Federal Hydropower System biological opinion.

  15. Electrodeposited Biaxially Textured Buffer Layers for YBCO Superconductors

    SciTech Connect

    Bhattacharya, R.; Phok, S.; Zhao, W.; Norman, A.

    2009-06-01

    Non-vacuum electrodeposition (ED) was used to prepare simplified Gd{sub 2}O{sub 3}/Gd{sub 2}Zr{sub 2}O{sub 7} and CeO{sub 2}/Gd{sub 2}Zr{sub 2}O{sub 7} buffer layers on a Ni-W substrate. Post-annealing conditions of electrodeposited precursor films were optimized to obtain high-quality biaxially textured buffer layers. The buffer layers were characterized by X-ray diffraction, optical profiling, and transmission electron microscopy (TEM). The effect of the cap layer thickness on the surface morphology and texture of the buffers was also studied. The microstructure of CeO{sub 2}/Gd{sub 2}Zr{sub 2}O{sub 7} was analyzed and compared to Gd{sub 2}O{sub 3}/Gd{sub 2}Zr{sub 2}O{sub 7}. The high-resolution TEM shows biaxially textured crystalline elctrodeposited Gd{sub 2}O{sub 3} and CeO{sub 2} cap layers on the electrodeposited Gd{sub 2}Zr{sub 2}O{sub 7} layers without any defects. YBa{sub 2}Cu{sub 3}O{sub 7}-delta (YBCO) superconductor was deposited by pulsed laser deposition (PLD) on the simplified ED-Gd{sub 2}O{sub 3}/Gd{sub 2}Zr{sub 2}O{sub 7} and ED-CeO{sub 2}/Gd{sub 2}Zr{sub 2}O{sub 7} buffers. Transport current density of 3.3 MA/cm{sup 2} at 77 K was obtained for PLD YBCO deposited on ED-Gd{sub 2}O{sub 3}/Gd{sub 2}Zr{sub 2}O{sub 7} buffer layers.

  16. Spectroscopy and quantum control of cryogenically buffered polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Patterson, David

    2016-05-01

    Cold polyatomic molecules offer rich possibilities for precision measurement, quantum control, and tests of fundamental symmetries. While manipulating, cooling, and detecting atoms and certain diatomic molecules at the single quantum state level is now possible, analogous tools for controlling polyatomic molecules lag far behind. Buffer gas cooling has emerged as a versatile tool for cooling such molecules. We will present recent demonstrations of state-specific and enantiomer-specific preparation of chiral molecules, and novel sensitive and ultra-specific chemical analysis techniques enabled by the combination of modern microwave spectroscopy techniques and the broad applicability of cryogenically buffered molecular samples.

  17. Influence of glyphosate on the copper dissolution in phosphate buffer

    NASA Astrophysics Data System (ADS)

    Coutinho, C. F. B.; Silva, M. O.; Machado, S. A. S.; Mazo, L. H.

    2007-01-01

    The electrochemical behavior of copper microelectrode in phosphate buffer in the presence of glyphosate was investigated by electrochemical techniques. It was observed that the additions of glyphosate in the phosphate buffer increased the anodic current of copper microelectrode and the electrochemical dissolution was observed. This phenomenon could be associated with the Cu(II) complexation by glyphosate forming a soluble complex. Physical characterization of the surface showed that, in absence of glyphosate, an insoluble layer covered the copper surface; on the other hand, in presence of glyphosate, it was observed a corroded copper surface with the formation of glyphosate complex in solution.

  18. Assembly and organization of poly(3-hexylthiophene) brushes and their potential use as novel anode buffer layers for organic photovoltaics.

    PubMed

    Alonzo, José; Kochemba, W Michael; Pickel, Deanna L; Ramanathan, Muruganathan; Sun, Zhenzhong; Li, Dawen; Chen, Jihua; Sumpter, Bobby G; Heller, William T; Kilbey, S Michael

    2013-10-01

    Buffer layers that control electrochemical reactions and physical interactions at electrode/film interfaces are key components of an organic photovoltaic cell. Here the structure and properties of layers of semi-rigid poly(3-hexylthiophene) (P3HT) chains tethered at a surface are investigated, and these functional systems are applied in an organic photovoltaic device. Areal density of P3HT chains is readily tuned through the choice of polymer molecular weight and annealing conditions, and insights from optical absorption spectroscopy and semiempirical quantum calculation methods suggest that tethering causes intrachain defects that affect co-facial π-stacking of brush chains. Because of their ability to modify oxide surfaces, P3HT brushes are utilized as an anode buffer layer in a P3HT-PCBM (phenyl-C₆₁-butyric acid methyl ester) bulk heterojunction device. Current-voltage characterization shows a significant enhancement in short circuit current, suggesting the potential of these novel nanostructured buffer layers to replace the PEDOT:PSS buffer layer typically applied in traditional P3HT-PCBM solar cells. PMID:23955069

  19. Comparison of adhesive properties of water- and phosphate-buffer-washed cottonseed meals with cottonseed protein isolate on bonding maple and poplar veneers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water- and phosphate buffer (35 mM Na2HPO4/NaH2PO4, pH 7.5)-washed cottonseed meals (abbreviated as WCM and BCM, respectively) could be low-cost and environmentally friendly protein-based adhesives as their preparation does not involve corrosive alkali and acid solutions that are needed for cottonse...

  20. An Efficient Protocol for the Oxidative Hydrolysis of Ketone SAMP Hydrazones Employing SeO(2) and H(2)O(2) under Buffered (pH 7) Conditions.

    PubMed

    Smith, Amos B; Liu, Zhuqing; Simov, Vladimir

    2009-06-01

    An effective oxidative protocol for the liberation of ketones from SAMP hydrazones employing peroxyselenous acid under aqueous buffered conditions (pH 7) has been developed. The procedure proceeds without epimerization of adjacent stereocenters or dehydration, respectively, in representative SAMP alkylation and aldol reaction adducts. PMID:20657727

  1. TRIO: Burst Buffer Based I/O Orchestration

    SciTech Connect

    Wang, Teng; Oral, H Sarp; Pritchard, Michael; Wang, Bin; Yu, Weikuan

    2015-01-01

    The growing computing power on leadership HPC systems is often accompanied by ever-escalating failure rates. Checkpointing is a common defensive mechanism used by scientific applications for failure recovery. However, directly writing the large and bursty checkpointing dataset to parallel filesystem can incur significant I/O contention on storage servers. Such contention in turn degrades the raw bandwidth utilization of storage servers and prolongs the average job I/O time of concurrent applications. Recently burst buffer has been proposed as an intermediate layer to absorb the bursty I/O traffic from compute nodes to storage backend. But an I/O orchestration mechanism is still desired to efficiently move checkpointing data from bursty buffers to storage backend. In this paper, we propose a burst buffer based I/O orchestration framework, named TRIO, to intercept and reshape the bursty writes for better sequential write traffic to storage severs. Meanwhile, TRIO coordinates the flushing orders among concurrent burst buffers to alleviate the contention on storage server bandwidth. Our experimental results reveal that TRIO can deliver 30.5% higher bandwidth and reduce the average job I/O time by 37% on average for data-intensive applications in various checkpointing scenarios.

  2. Woven graphite epoxy composite test specimens with glass buffer strips

    NASA Technical Reports Server (NTRS)

    Bonnar, G. R.; Palmer, R. J.

    1982-01-01

    Woven unidirectional graphite cloth with bands of fiberglass replacing the graphite in discrete lengthwise locations was impregnated with epoxy resin and used to fabricate a series of composite tensile and shear specimens. The finished panels, with the fiberglass buffer strips, were tested. Details of the fabrication process are reported.

  3. Hypothalamic oxytocin mediates social buffering of the stress response

    PubMed Central

    Smith, Adam S.; Wang, Zuoxin

    2013-01-01

    Background While stressful life events can enhance the risk of mental disorders, positive social interactions can propagate good mental health and normal behavioral routines. Still, the neural systems that promote these benefits are undetermined. Oxytocin is a hormone involved in social behavior and stress; thus, we focus on the impact that social buffering has on the stress response and the governing effects of oxytocin. Methods Female prairie voles (Microtus ochrogaster) were exposed to 1 hr immobilization stress then recovered alone or with their male partner to characterize the effect of social contact on the behavioral, physiological, and neuroendocrine stress response. In addition, we treated immobilized females recovering alone with oxytocin, or vehicle, and females recovering with their male partner with a selective oxytocin receptor antagonist, or vehicle. Group sizes varied from 6 to 8 voles (n = 98 total). Results We found that 1 hr immobilization increased anxiety-like behaviors and circulating levels of corticosterone, a stress hormone, in females recovering alone, but not the females recovering with their male partner. This social buffering by the male partner on biobehavioral responses to stress was accompanied by increased oxytocin release in the paraventricular nucleus (PVN) of the hypothalamus. Intra-PVN oxytocin injections reduced behavioral and corticosterone responses to immobilization whereas injections of an oxytocin receptor antagonist blocked the effects of the social buffering. Conclusions Together, our data demonstrate that PVN oxytocin mediates the social buffering effects on the stress response, and thus may be a target for treatment of stress-related disorders. PMID:24183103

  4. Odor Mitigation with Tree Buffers: Swine Production Case Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tree buffers are a potential low cost sustainable odor mitigation strategy, but there is little to no data on their effectiveness. Odor transport is thought to occur one of two ways either directly through vapor phase transport or indirectly through sorption onto particles. Consequently, monitoring...

  5. Dominant oceanic bacteria secure phosphate using a large extracellular buffer.

    PubMed

    Zubkov, Mikhail V; Martin, Adrian P; Hartmann, Manuela; Grob, Carolina; Scanlan, David J

    2015-01-01

    The ubiquitous SAR11 and Prochlorococcus bacteria manage to maintain a sufficient supply of phosphate in phosphate-poor surface waters of the North Atlantic subtropical gyre. Furthermore, it seems that their phosphate uptake may counter-intuitively be lower in more productive tropical waters, as if their cellular demand for phosphate decreases there. By flow sorting (33)P-phosphate-pulsed (32)P-phosphate-chased cells, we demonstrate that both Prochlorococcus and SAR11 cells exploit an extracellular buffer of labile phosphate up to 5-40 times larger than the amount of phosphate required to replicate their chromosomes. Mathematical modelling is shown to support this conclusion. The fuller the buffer the slower the cellular uptake of phosphate, to the point that in phosphate-replete tropical waters, cells can saturate their buffer and their phosphate uptake becomes marginal. Hence, buffer stocking is a generic, growth-securing adaptation for SAR11 and Prochlorococcus bacteria, which lack internal reserves to reduce their dependency on bioavailable ambient phosphate. PMID:26198420

  6. A model for monitoring of Hsp90-buffered genetic variations

    NASA Astrophysics Data System (ADS)

    Kozeko, Liudmyla

    Genetic material of terrestrial organisms can be considerably injured by cosmic rays and UV-radiation in the space environment. Organisms onboard are also exposed to the entire complex of negative physical factors which can generate genetic variations and affect morphogenesis. However, species phenotypes must be robust to genetic variation, requiring "buffering" systems to ensure normal development. The molecular chaperone Hsp90 can serve as such "a buffer". It is important in the maturation and conformational regulation of a diverse set of signal transducers. The requirement of many principal regulatory proteins for Hsp90 renders entire metabolic pathways sensitive to impairment of its function. So inhibition of Hsp90 function can open cryptic genetic variations and produce morphological changes. In this paper, we present a model for monitoring of cryptic Hsp90-buffered genetic variations arising during exposure to space and spaceflight factors. This model has been developed with Arabidopsis thaliana seeds gathered in natural habitats with high anthropogenic pressure and wild type (Col-0) seeds subjected to negative influences (UV, heavy metals) experimentally. The phenotypic traits of early seedlings grown under reduction of Hsp90 activity were characterized to estimate Hsp90-buffered genetic variations. Geldanamycin was used as an inhibitor of Hsp90 function.

  7. Evaluating uncertainty in E. coli retention in vegetated buffer strips

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetated buffer strips (VFS) separate fields and pastures from streams and other water bodies and can serve as barriers that prevent sediment and agricultural chemicals from entering waterways and spoiling them. Growing concern about the manure-borne pathogens as water pollutants defines the need t...

  8. Effects of Terrestrial Buffer Zones on Amphibians on Golf Courses

    PubMed Central

    Puglis, Holly J.; Boone, Michelle D.

    2012-01-01

    A major cause of amphibian declines worldwide is habitat destruction or alteration. Public green spaces, such as golf courses and parks, could serve as safe havens to curb the effects of habitat loss if managed in ways to bolster local amphibian communities. We reared larval Blanchard's cricket frogs (Acris blanchardi) and green frogs (Rana clamitans) in golf course ponds with and without 1 m terrestrial buffer zones, and released marked cricket frog metamorphs at the golf course ponds they were reared in. Larval survival of both species was affected by the presence of a buffer zone, with increased survival for cricket frogs and decreased survival for green frogs when reared in ponds with buffer zones. No marked cricket frog juveniles were recovered at any golf course pond in the following year, suggesting that most animals died or migrated. In a separate study, we released cricket frogs in a terrestrial pen and allowed them to choose between mown and unmown grass. Cricket frogs had a greater probability of using unmown versus mown grass. Our results suggest that incorporating buffer zones around ponds can offer suitable habitat for some amphibian species and can improve the quality of the aquatic environment for some sensitive local amphibians. PMID:22761833

  9. A Longitudinal Study of Stress Buffering for Adolescent Problem Behaviors.

    ERIC Educational Resources Information Center

    Windle, Michael

    1992-01-01

    In a study of middle adolescents, the interrelationships between stressful events, perceived social support, internalization of problems, and externalization of problems were examined. Social support did not act as a buffer of stress. Stressful events and low family support predicted problem behaviors for adolescent girls. (BC)

  10. Dominant oceanic bacteria secure phosphate using a large extracellular buffer

    PubMed Central

    Zubkov, Mikhail V.; Martin, Adrian P.; Hartmann, Manuela; Grob, Carolina; Scanlan, David J.

    2015-01-01

    The ubiquitous SAR11 and Prochlorococcus bacteria manage to maintain a sufficient supply of phosphate in phosphate-poor surface waters of the North Atlantic subtropical gyre. Furthermore, it seems that their phosphate uptake may counter-intuitively be lower in more productive tropical waters, as if their cellular demand for phosphate decreases there. By flow sorting 33P-phosphate-pulsed 32P-phosphate-chased cells, we demonstrate that both Prochlorococcus and SAR11 cells exploit an extracellular buffer of labile phosphate up to 5–40 times larger than the amount of phosphate required to replicate their chromosomes. Mathematical modelling is shown to support this conclusion. The fuller the buffer the slower the cellular uptake of phosphate, to the point that in phosphate-replete tropical waters, cells can saturate their buffer and their phosphate uptake becomes marginal. Hence, buffer stocking is a generic, growth-securing adaptation for SAR11 and Prochlorococcus bacteria, which lack internal reserves to reduce their dependency on bioavailable ambient phosphate. PMID:26198420

  11. Odor mitigation with vegetative buffers: Swine production case study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetative environmental buffers (VEB) are a potentially low cost sustainable odor mitigation strategy, but there is little to no data supporting their effectiveness. Wind tunnel experiments and field monitoring were used to determine the effect VEB had on wind flow patterns within a swine facility....

  12. NITROUS OXIDE EMISSIONS FROM RIPARIAN BUFFERS AND TREATMENT WETLANDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian buffers and treatment wetlands are used throughout the world for the protection of water bodies from nonpoint source pollution, particularly nitrogen. Yet, relatively few studies of riparian or treatment wetland denitrification consider the production of nitrous oxide. Nitrous oxide emissio...

  13. Diazinon and permethrin mitigation across a grass-wetland buffer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Various management practices have been proposed to help alleviate deleterious effects of pesticides associated with agricultural runoff. Vegetated buffers of different designs are often used as edge-of-field treatment practices. Two experimental systems, a control (no vegetation) and a grass-wetla...

  14. Creating a replicable, valid cross-platform buffering technique: The sausage network buffer for measuring food and physical activity built environments

    PubMed Central

    2012-01-01

    Background Obesity researchers increasingly use geographic information systems to measure exposure and access in neighborhood food and physical activity environments. This paper proposes a network buffering approach, the “sausage” buffer. This method can be consistently and easily replicated across software versions and platforms, avoiding problems with proprietary systems that use different approaches in creating such buffers. Methods In this paper, we describe how the sausage buffering approach was developed to be repeatable across platforms and places. We also examine how the sausage buffer compares with existing alternatives in terms of buffer size and shape, measurements of the food and physical activity environments, and associations between environmental features and health-related behaviors. We test the proposed buffering approach using data from EAT 2010 (Eating and Activity in Teens), a study examining multi-level factors associated with eating, physical activity, and weight status in adolescents (n = 2,724) in the Minneapolis/St. Paul metropolitan area of Minnesota. Results Results show that the sausage buffer is comparable in area to the classic ArcView 3.3 network buffer particularly for larger buffer sizes. It obtains similar results to other buffering techniques when measuring variables associated with the food and physical activity environments and when measuring the correlations between such variables and outcomes such as physical activity and food purchases. Conclusions Findings from various tests in the current study show that researchers can obtain results using sausage buffers that are similar to results they would obtain by using other buffering techniques. However, unlike proprietary buffering techniques, the sausage buffer approach can be replicated across software programs and versions, allowing more independence of research from specific software. PMID:22554353

  15. Improvements in multimedia data buffering using master/slave architecture

    SciTech Connect

    Sheikh, S.; Ganesan, R.

    1996-12-31

    Advances in the networking technology and multimedia technology has necessitated a need for multimedia servers to be robust and reliable. Existing solutions have direct limitations such as I/O bottleneck and reliability of data retrieval. The system can store the stream of incoming data if enough buffer space is available or the mass storage is clearing the buffer data faster than queue input. A single buffer queue is not sufficient to handle the large frames. Queue sizes are normally several megabytes in length and thus in turn will introduce a state of overflow. The system should also keep track of the rewind, fast forwarding, and pause requests, otherwise queue management will become intricate. In this paper, we present a master/slave (server that is designated to monitor the workflow of the complete system. This server holds every other information of slaves by maintaining a dynamic table. It also controls the workload on each of the systems by redistributing request to others or handles the request by itself) approach which will overcome the limitations of today`s storage and also satisfy tomorrow`s storage needs. This approach will maintain the system reliability and yield faster response by using more storage units in parallel. A network of master/slave can handle many requests and synchronize them at all times. Using dedicated CPU and a common pool of queues we explain how queues can be controlled and buffer overflow can be avoided. We propose a layered approach to the buffering problem and provide a read-ahead solution to ensure continuous storage and retrieval of multimedia data.

  16. Cybernetic principles of aging and rejuvenation: the buffering- challenging strategy for life extension.

    PubMed

    Heylighen, Francis

    2014-01-01

    Aging is analyzed as the spontaneous loss of adaptivity and increase in fragility that characterizes dynamic systems. Cybernetics defines the general regulatory mechanisms that a system can use to prevent or repair the damage produced by disturbances. According to the law of requisite variety, disturbances can be held in check by maximizing buffering capacity, range of compensatory actions, and knowledge about which action to apply to which disturbance. This suggests a general strategy for rejuvenating the organism by increasing its capabilities of adaptation. Buffering can be optimized by providing sufficient rest together with plenty of nutrients: amino acids, antioxidants, methyl donors, vitamins, minerals, etc. Knowledge and the range of action can be extended by subjecting the organism to an as large as possible variety of challenges. These challenges are ideally brief so as not to deplete resources and produce irreversible damage. However, they should be sufficiently intense and unpredictable to induce an overshoot in the mobilization of resources for damage repair, and to stimulate the organism to build stronger capabilities for tackling future challenges. This allows them to override the trade-offs and limitations that evolution has built into the organism's repair processes in order to conserve potentially scarce resources. Such acute, "hormetic" stressors strengthen the organism in part via the "order from noise" mechanism that destroys dysfunctional structures by subjecting them to strong, random variations. They include heat and cold, physical exertion, exposure, stretching, vibration, fasting, food toxins, micro-organisms, environmental enrichment and psychological challenges. The proposed buffering-challenging strategy may be able to extend life indefinitely, by forcing a periodic rebuilding and extension of capabilities, while using the Internet as an endless source of new knowledge about how to deal with disturbances. PMID:24852018

  17. The Conjugate Acid-Base Chart.

    ERIC Educational Resources Information Center

    Treptow, Richard S.

    1986-01-01

    Discusses the difficulties that beginning chemistry students have in understanding acid-base chemistry. Describes the use of conjugate acid-base charts in helping students visualize the conjugate relationship. Addresses chart construction, metal ions, buffers and pH titrations, and the organic functional groups and nonaqueous solvents. (TW)

  18. Isotherm parameters and intraparticle mass transfer kinetics on molecularly imprinted polymers in acetonitrile/buffer mobile phases

    SciTech Connect

    Kim, Hyunjung; Kaczmarski, Krzysztof; Guiochon, Georges A

    2006-03-01

    The equilibrium isotherm and the intraparticle mass transfer kinetics of the enantiomers of the template were investigated on an Fmoc-L-tryptophan (Fmoc-L-Trp) imprinted polymer at different pHs and water concentrations in acetonitrile/aqueous buffer mobile phases. The equilibrium isotherm data were measured using frontal analysis at 25 {+-} 2 C. The adsorption energy distribution was found to be trimodal, with narrow modes. Consistent with this distribution, the adsorption data were modeled using a tri-Langmuir isotherm equation and the best estimates of the isotherm parameters were determined. The intraparticle mass transfer parameters were derived by comparing the profiles of experimental overloaded bands and the profiles calculated using the isotherm model and the lumped pore diffusion (POR) model of chromatography. These results showed that different adsorption and mass transfer mechanisms exist in mobile phases made of acetonitrile/aqueous buffer and of acetonitrile/acetic acid solutions.

  19. The dependence of the lipid bilayer membrane: buffer partition coefficient of pentobarbitone on pH and lipid composition.

    PubMed Central

    Miller, K W; Yu, S C

    1977-01-01

    1 The membrane/buffer partition coefficient of [14C]-pentobarbitone has been determined as a function of the lipid composition of bilayer membranes. 2 A new technique based on ultrafiltration gave comparable results to conventional techniques but required less time for equilbration. 3 The membrane/buffer coefficient was independent of pentobarbitone concentration in the range studies. 4 The apparent partition coefficient varied with pH and was a linear function of the degree of dissociation of pentobarbition. 5 Both the charged and uncharged forms of pentobarbitone partitioned into the membrane, the latter to a much greater extent than the former. 6 At low pH the highest partition coefficient observed was in egg phosphatidylcholine bilayer membranes. 7 Incorporation of cholesterol or phosphatidic acid into phosphatidylcholine membranes greatly reduced the partition coefficient. 8 High pressures do not greatly change these partition coefficients. PMID:21013

  20. A Buffered Alcohol-Based Fixative for Histomorphologic and Molecular Applications.

    PubMed

    Perry, Candice; Chung, Joon-Yong; Ylaya, Kris; Choi, Chel Hun; Simpson, Amari; Matsumoto, Kaipo T; Smith, William A; Hewitt, Stephen M

    2016-07-01

    Formalin-fixed paraffin-embedded (FFPE) tissue is the predominant preparation for diagnostic histopathological evaluation and increasingly the biospecimen on which molecular diagnostics are performed. However, formalin is carcinogenic and results in cross-linking of proteins and nicking and alterations of nucleic acids. Alternative fixatives, including 70% ethanol, improved biomolecular integrity; however, they have yet to replace neutral-buffered formalin (NBF). Herein, we describe the phosphate-buffered ethanol 70% (BE70) fixative. The histomorphology of BE70-fixed tissue is very similar to that of NBF; however, it is a non-cross-linking fixative and lacks the carcinogenic profile of formaldehyde-based fixatives. RNA isolated from tissue fixed in BE70 was of substantially higher quality and quantity than that was recovered from formalin-fixed tissue. Furthermore, the BE70 fixative showed excellent RNA and DNA integrity compared with that of NBF fixative based on real-time polymerase chain reaction analysis results. Immunohistochemical staining was similar for the antigen tested. In conclusion, BE70 is a non-cross-linking fixative that is superior to NBF and 70% ethanol with reference to biomolecule recovery and quality from paraffin-embedded tissue. Additional studies to compare the histomorphologic and immunohistochemical performance and utility in a clinical setting are required. PMID:27221702

  1. Cytoplasmic calcium buffers in intact human red cells.

    PubMed Central

    Tiffert, T; Lew, V L

    1997-01-01

    1. Precise knowledge of the cytoplasmic Ca2+ buffering behaviour in intact human red cells is essential for the characterization of their [Ca2+]i-dependent functions. This was investigated by using a refined method and experimental protocols which allowed continuity in the estimates of [Ca2+]i, from nanomolar to millimolar concentrations, in the presence and absence of external Ca2+ chelators. 2. The study was carried out in human red cells whose plasma membrane Ca2+ pump was inhibited either by depleting the cells of ATP or by adding vanadate to the cell suspension. Cytoplasmic Ca2+ buffering was analysed from plots of total cell calcium content vs. ionized cytoplasmic Ca2+ concentration ([CaT]i vs. [Ca2+]i) obtained from measurements of the equilibrium distribution of 45Ca2+ at different external Ca2+ concentrations ([Ca2+]o), in conditions known to clamp cell volume and pH. The equilibrium distribution of 45Ca2+ was induced by the divalent cation ionophore A23187. 3. The results showed the following. (i) The known red cell Ca2+ buffer represented by alpha, with a large capacity and low Ca2+ affinity, was the main cytoplasmic Ca2+ binding agent. (ii) The value of alpha was remarkably constant; the means for each of four donors ranged from 0.33 to 0.35, with a combined value of all independent measurements of 0.34 +/- 0.01 (mean +/- S.E.M., n = 16). This contrasts with the variability previously reported. (iii) There was an additional Ca2+ buffering complex with a low capacity (approximately 80 micromol (340 g Hb)(-1)) and intermediate Ca2+ affinity (apparent dissociation constant, K(D,app) approximately 4-50 microM) whose possible identity is discussed. (iv) The cell content of putative Ca2+ buffers with submicromolar Ca2+ dissociation constants was below the detection limit of the methods used here (less than 2 micromol (340 g Hb)(-1)). 4. Vanadate (1 mM) inhibited the Vmax of the Ca2+ pump in inosine-fed cells by 99.7%. The cytoplasmic Ca2+ buffering behaviour

  2. Ultrasonic monitoring of material processing using clad buffer rod sensors

    NASA Astrophysics Data System (ADS)

    Ramos Franca, Demartonne

    Ultrasonic sensors and techniques are developed for in-line monitoring of polymer extrusion, cleanliness of molten metals and liquid flow speed at elevated temperature. Pulse-echo mode is used for the first two processes, while the through-transmission mode is applied in the third one. The ultrasonic probe consists of high performance clad buffer rods with different dimensions to thermally isolate the commercial ultrasonic transducer from materials at high temperature. The clad buffer rods are made of steel, polymer and ceramic. Steel clad buffer rods are introduced for in-line monitoring of polymer extrusion processes. Owing to its superior performance in pulse-echo mode, for the first time such a probe is installed and performs ultrasonic monitoring in the die of a co-extrusion machine and in the barrel section of a twin-screw extruder. It can reveal a variety of information relevant to process parameters, such as polymer layer thickness, interface location and adhesion quality, stability, or polymer composition change. For the ultrasonic monitoring of polymer processes, probes with acoustic impedance that matches that of the processed polymer may offer certain advantages such as quantitative viscoelastic evaluation; thus high temperature polymer clad buffer rods, in particular PEEK, are developed. It is demonstrated that this new probe exhibits unique advantages for in-line monitoring of the cure of epoxies and polymer extrusion process. Long steel clad buffer rods with a spherical focus lens machined at the probing end are proposed for cleanliness evaluation of molten metals. The potential of this focusing probe is demonstrated by means of high-resolution imaging and particles detection in molten zinc at temperatures higher than 600°C, using a single probe operated at pulse-echo mode. A contrapropagating ultrasonic flowmeter employing steel clad buffer rods is devised to operate at high temperature. It is demonstrated that these rods guide ultrasonic signals

  3. Mobile and immobile calcium buffers in bovine adrenal chromaffin cells.

    PubMed Central

    Zhou, Z; Neher, E

    1993-01-01

    1. The calcium binding capacity (kappa S) of bovine chromaffin cells preloaded with fura-2 was measured during nystatin-perforated-patch recordings. 2. Subsequently, the perforated patch was ruptured to obtain a whole-cell recording situation, and the time course of kappa S was monitored during periods of up to one hour. 3. No rapid change (within 10-20 s) of kappa S was observed upon transition to whole-cell recording, as would be expected, if highly mobile organic anions contributed significantly to calcium buffering. However, approximately half of the cells investigated displayed a drop in kappa S within 2-5 min, indicative of the loss of soluble Ca2+ binding proteins in the range of 7-20 kDa. 4. The average Ca2+ binding capacity (differential ratio of bound calcium over free calcium) was 9 +/- 7 (mean +/- S.E.M.) for the poorly mobile component and 31 +/- 10 for the fixed component. It was concluded that a contribution of 7 from highly mobile buffer would have been detected, if present. Thus, this value can be considered as an upper bound to highly mobile Ca2+ buffer. 5. Both mobile and fixed calcium binding capacity appeared to have relatively low Ca2+ affinity, since kappa S did not change in the range of Ca2+ concentrations between 0.1 and 3 microM. 6. It was found that cellular autofluorescence and contributions to fluorescence of non-hydrolysed or compartmentalized dye contribute a serious error in estimation of kappa S. 'Balanced loading', a degree of fura-2 loading such that the calcium binding capacity of fura-2 equals cellular calcium binding capacity, minimizes these errors. Also, changes in kappa S at the transition from perforated-patch to whole-cell recording can be most faithfully recorded for similar degrees of loading in both situations. 7. Nystatin was found unable to make pores from inside of the plasma membrane of chromaffin cells. With careful preparation and storage the diluted nystatin solution maintained its high activity of membrane

  4. Assessment and preliminary design of an energy buffer for regenerative braking in electric vehicles

    NASA Technical Reports Server (NTRS)

    Buchholz, R.; Mathur, A. K.

    1979-01-01

    Energy buffer systems, capable of storing the vehicle energy during braking and reusing this stored energy during acceleration, were examined. Some of these buffer systems when incorporated in an electric vehicle would result in an improvement in the performance and range under stop and go driving conditions. Buffer systems considered included flywheels, hydropneumatic, pneumatic, spring, and regenerative braking. Buffer ranking and rating criteria were established. Buffer systems were rated based on predicted range improvements, consumer acceptance, driveability, safety, reliability and durability, and initial and life cycle costs. A hydropneumatic buffer system was selected.

  5. Endogenous Cytosolic Ca2+ Buffering is Necessary for TRPM4 Activity in Cerebral Artery Smooth Muscle Cells

    PubMed Central

    Gonzales, Albert L.; Earley, Scott

    2011-01-01

    The melastatin transient receptor potential (TRP) channel, TRPM4, is a critical regulator of smooth muscle membrane potential and arterial tone. Activation of the channel is Ca2+-dependent, but prolonged exposures to high global Ca2+ causes rapid inactivation under conventional whole-cell patch clamp conditions. Using amphotericin B perforated whole cell patch clamp electrophysiology, which minimally disrupts cytosolic Ca2+ dynamics, we recently showed that Ca2+ released from inositol trisphosphate receptors (IP3R) on the sarcoplasmic reticulum (SR) activates TRPM4 channels, producing sustained Transient Inward Cation Currents (TICCs). Thus, Ca2+-dependent inactivation of TRPM4 may not be inherent to the channel itself but rather is a result of the recording conditions. We hypothesized that under conventional whole-cell configurations, loss of intrinsic cytosolic Ca2+ buffering following cell dialysis contributes to inactivation of TRPM4 channels. With the inclusion of the Ca2+ buffers ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA, 10 mM) or bis-ethane-N,N,N′,N′-tetraacetic acid (BAPTA, 0.1 mM) in the pipette solution, we mimic endogenous Ca2+ buffering and record novel, sustained whole-cell TICC activity from freshly-isolated cerebral artery myocytes. Biophysical properties of TICCs recorded under perforated and whole-cell patch clamp were nearly identical. Furthermore, whole-cell TICC activity was reduced by the selective TRPM4 inhibitor, 9-phenanthrol, and by siRNA-mediated knockdown of TRPM4. When a higher concentration (10 mM) of BAPTA was included in the pipette solution, TICC activity was disrupted, suggesting that TRPM4 channels on the plasma membrane and IP3R on the SR are closely opposed but not physically coupled, and that endogenous Ca2+ buffer proteins play a critical role in maintaining TRPM4 channel activity in native cerebral artery smooth muscle cells. PMID:22153976

  6. A 128K-bit CCD buffer memory system

    NASA Technical Reports Server (NTRS)

    Siemens, K. H.; Wallace, R. W.; Robinson, C. R.

    1976-01-01

    A prototype system was implemented to demonstrate that CCD's can be applied advantageously to the problem of low power digital storage and particularly to the problem of interfacing widely varying data rates. 8K-bit CCD shift register memories were used to construct a feasibility model 128K-bit buffer memory system. Peak power dissipation during a data transfer is less than 7 W., while idle power is approximately 5.4 W. The system features automatic data input synchronization with the recirculating CCD memory block start address. Descriptions are provided of both the buffer memory system and a custom tester that was used to exercise the memory. The testing procedures and testing results are discussed. Suggestions are provided for further development with regards to the utilization of advanced versions of CCD memory devices to both simplified and expanded memory system applications.

  7. A general approach to dynamic packet routing with bounded buffers

    SciTech Connect

    Broder, A.Z.; Frieze, A.M.; Upfal, E. |

    1996-12-31

    We prove a sufficient condition for the stability of dynamic packet routing algorithms. Our approach reduces the problem of steady state analysis to the easier and better understood question of static routing. We show that certain high probability and worst case bounds on the quasistatic (finite past) performance of a routing algorithm imply bounds on the performance of the dynamic version of that algorithm. Our technique is particularly useful in analyzing routing on networks with bounded buffers where complicated dependencies make standard queuing techniques inapplicable. We present several applications of our approach. In all cases we start from a known static algorithm, and modify it to fit our framework. In particular we give the first dynamic algorithm for routing on a butterfly with bounded buffers. Both the injection rate for which the algorithm is stable, and the expected time a packet spends in the system are optimal up to constant factors. Our approach is also applicable to the recently introduced adversarial input model.

  8. Social Support Can Buffer against Stress and Shape Brain Activity

    PubMed Central

    Hostinar, Camelia E.; Gunnar, Megan R.

    2015-01-01

    Social support from close relationship partners is an important resource for coping with stress, particularly during childhood. We discuss ethical challenges associated with studying stress and its social buffering in the laboratory, as well as emerging evidence regarding two potential neural substrates for the social buffering of stress: hypothalamic oxytocin activity and activation of areas in the prefrontal cortex associated with effective self-regulation. We also address the role of early-life social experiences in shaping brain development, as well as recommendations for practice and policy that would advance the ethical treatment of children and reduce social inequalities in early-life experiences and opportunities–e.g., investing in programs that prevent child maltreatment and facilitating access to high-quality child care for economically disadvantaged families. We also debate the ethical implications of using oxytocin nasal sprays to simulate the stress-reducing properties of social support and advise waiting for more evidence before recommending their use. PMID:26478822

  9. Electrokinetic determination of the buffer capacity of Andisols.

    PubMed

    Vázquez, Mario V; Hernández-Luis, Felipe; Benjumea, Dora; Grandoso, Domingo; Lemus, Mercedes; Arbelo, Carmen D

    2007-05-25

    Among methods which involve the flow of electric current, the electro-remediation techniques have shown useful both for the removal of polluting species, and for obtaining a series of parameters in relatively laboratory simple experiments which can be used to characterize soils. This technique was applied in the present study to obtain experimental results with two soils from Tenerife. The capacity of the method as methodology for the measurement of the buffering capacity of these soils during electrokinetic experiments was analyzed. The results obtained on electrokinetic determination of buffer capacity correlated quite well with behaviour observed in the pH curves. The technique was promising for soil description primarily because important information could be obtained in shorter time periods than those required when using routine laboratory methods of soil analysis. PMID:17320934

  10. Buffered coscheduling for parallel programming and enhanced fault tolerance

    DOEpatents

    Petrini, Fabrizio; Feng, Wu-chun

    2006-01-31

    A computer implemented method schedules processor jobs on a network of parallel machine processors or distributed system processors. Control information communications generated by each process performed by each processor during a defined time interval is accumulated in buffers, where adjacent time intervals are separated by strobe intervals for a global exchange of control information. A global exchange of the control information communications at the end of each defined time interval is performed during an intervening strobe interval so that each processor is informed by all of the other processors of the number of incoming jobs to be received by each processor in a subsequent time interval. The buffered coscheduling method of this invention also enhances the fault tolerance of a network of parallel machine processors or distributed system processors

  11. Dynamic behavior of elevator compensating sheave during buffer strike

    NASA Astrophysics Data System (ADS)

    Watanabe, S.; Okawa, T.

    2016-05-01

    This paper shows an elevator dynamic model that calculates the compensating sheave motion during a buffer strike. Our equivalent 2-degree-of-freedom vibration model of an elevator system, which consists of a car, a compensating sheave, and compensating ropes, can evaluate the dynamic tension of the compensating ropes caused by a buffer strike. The constraint force, which restricts the upward motion of the compensating sheave, is estimated from the dynamic rope tension. The constraint force is represented by the summation of two vibration modes and is the function of the limited distance of the compensating sheave's upward movement. Our formula, which evaluates the maximum constraint force, shows that a shorter limited distance of the compensating sheave increases the constraint force.

  12. Fast Pixel Buffer For Processing With Lookup Tables

    NASA Technical Reports Server (NTRS)

    Fisher, Timothy E.

    1992-01-01

    Proposed scheme for buffering data on intensities of picture elements (pixels) of image increases rate or processing beyond that attainable when data read, one pixel at time, from main image memory. Scheme applied in design of specialized image-processing circuitry. Intended to optimize performance of processor in which electronic equivalent of address-lookup table used to address those pixels in main image memory required for processing.

  13. Focusing Light Beams To Improve Atomic-Vapor Optical Buffers

    NASA Technical Reports Server (NTRS)

    Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy

    2010-01-01

    Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal to improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal to use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible to optimize the physical conditions throughout a cell, thereby making it impossible to optimize the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, "to optimize" as used here means to design the cell so as to maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal to use incoherent optical pumping: For reasons too complex to describe here, residual absorption of light is one of the main impediments to achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior to that of a medium that exhibits EIT without Raman gain.

  14. Zn(2+)-cyclen-based complex enable a selective detection of single-stranded thymine-rich DNA in aqueous buffer.

    PubMed

    Zhu, Zece; Wang, Sheng; Wei, Danqing; Yang, Chuluo

    2016-11-15

    It is a big challenge to develop fluorescent probes for selective detection of DNA with specific sequences in aqueous buffers. We report a new tetraphenylethene-based Zn(2+)-cyclen complex (TPECyZn), and a chemo-sensing ensemble of the Zn complex with phenol red. TPECyZn showed significant fluorescence enhancement upon binding to thymine-rich DNA in HEPES buffers. But its selectivity was not high enough to eliminate the interference from some random DNA. By constructing the chemo-sensing ensemble of TPECyZn with phenol red, the background fluorescence was eliminated due to the energy transfer from TPECyZn to phenol red. Moreover, this chemo-sensing ensemble revealed high selectivity in detecting thymine-rich single-stranded DNA over other DNA in aqueous buffer. It can detect poly deoxythymidylic acid sequence as short as 2 nt. This detection in aqueous media makes this probe feasible in real application. PMID:27288711

  15. Positively charged and pH self-buffering quantum dots for efficient cellular uptake by charge mediation and monitoring cell membrane permeability

    NASA Astrophysics Data System (ADS)

    Wang, Suhua; Song, Haipeng; Ong, Wei Yi; Han, Ming Yong; Huang, Dejian

    2009-10-01

    Positively charged and pH self-buffering quantum dots (Tren-QDs) were achieved by surface functionalization with tris(2-aminoethyl)amine (Tren) derivatives, which are attached to the inorganic cores of QDs through bidentate chelating of dithiocarbamates. The Tren-QDs exhibit pH buffering capability by absorbing or releasing protons due to the surface polyamine groups as the surrounding pH fluctuates. Such self-buffering capability stabilizes the photoluminescence of the Tren-QDs against acid. The Tren-QDs bear positive charges through protonation of the surface polyamine groups under physiological conditions and the surface positive charges improve their cellular uptake efficiency by charge mediation, which has been demonstrated by BV-2 microglia cells. The photoluminescence of Tren-QDs shows a selective Stern-Volmer response to copper ions and this property has been preliminarily evaluated for investigating the BV-2 cell membrane structure by monitoring the photoluminescence of intracellular Tren-QDs.

  16. Magnetic bearings for a high-performance optical disk buffer

    NASA Technical Reports Server (NTRS)

    Hockney, Richard; Hawkey, Timothy

    1993-01-01

    An optical disk buffer concept can provide gigabit-per-second data rates and terabit capacity through the use of arrays of solid state lasers applied to a stack of erasable/reusable optical disks. The RCA optical disk buffer has evoked interest by NASA for space applications. The porous graphite air bearings in the rotary spindle as well as those used in the linear translation of the read/write head would be replaced by magnetic bearings or mechanical (ball or roller) bearings. Based upon past experience, roller or ball bearings for the translation stages are not feasible. Unsatisfactory, although limited experience exists with ball bearing spindles also. Magnetic bearings, however, appear ideally suited for both applications. The use of magnetic bearings is advantageous in the optical disk buffer because of the absence of physical contact between the rotating and stationary members. This frictionless operation leads to extended life and reduced drag. The manufacturing tolerances that are required to fabricate magnetic bearings would also be relaxed from those required for precision ball and gas bearings. Since magnetic bearings require no lubricant, they are inherently compatible with a space (vacuum) environment. Magnetic bearings also allow the dynamics of the rotor/bearing system to be altered through the use of active control. This provides the potential for reduced vibration, extended regions of stable operation, and more precise control of position.

  17. Electroejaculation and semen buffer evaluation in the microbat Carollia perspicillata.

    PubMed

    Fasel, Nicolas Jean; Helfenstein, Fabrice; Buff, Samuel; Richner, Heinz

    2015-03-15

    Scientific interests and conservation needs currently stress the necessity to better understanding bat reproductive biology. In this study, we present the first, safe, inexpensive, and reliable method to obtain sperm from a microbat species (Carollia perspicillata) by electroejaculation. This method revealed to be highly efficient (100% success rate). We obtained ejaculates composed of two characteristically different fractions. We compared three buffers and recommend using an Earle's balanced salt solution as a semen extender. Earle's balanced salt solution provided significant repeatable measure of swimming ability (intraclass correlation coefficient: 0.74, P < 0.01) and proportion of motile sperms (intraclass correlation coefficient: 0.08, P = 0.01) and allowed sperm to maintain optimal swimming capacity over time. None of the buffers could dissolve all the coagulated sperm. Although the trypsin buffer freed a larger fraction of spermatozoa in the ejaculate, it impaired swimming ability without improving motility, viability, and stamina. We thus argue that the sperm population analyzed with Earle's balanced salt solution is a representative of the ejaculate. Finally, we found that the mean sperm velocity of C perspicillata (78.8 μm/s) is lower than that predicted by regressing sperm velocity on relative testes mass, a proxy of sperm competition. The question as to whether C perspicillata is an outsider for sperm velocity, or whether bats evolved yet another unique mechanism to cope with sperm competition deserves more investigations. PMID:25541424

  18. Cell Electrosensitization Exists Only in Certain Electroporation Buffers

    PubMed Central

    Dermol, Janja; Pakhomova, Olga N.; Pakhomov, Andrei G.; Miklavčič, Damijan

    2016-01-01

    Electroporation-induced cell sensitization was described as the occurrence of a delayed hypersensitivity to electric pulses caused by pretreating cells with electric pulses. It was achieved by increasing the duration of the electroporation treatment at the same cumulative energy input. It could be exploited in electroporation-based treatments such as electrochemotherapy and tissue ablation with irreversible electroporation. The mechanisms responsible for cell sensitization, however, have not yet been identified. We investigated cell sensitization dynamics in five different electroporation buffers. We split a pulse train into two trains varying the delay between them and measured the propidium uptake by fluorescence microscopy. By fitting the first-order model to the experimental results, we determined the uptake due to each train (i.e. the first and the second) and the corresponding resealing constant. Cell sensitization was observed in the growth medium but not in other tested buffers. The effect of pulse repetition frequency, cell size change, cytoskeleton disruption and calcium influx do not adequately explain cell sensitization. Based on our results, we can conclude that cell sensitization is a sum of several processes and is buffer dependent. Further research is needed to determine its generality and to identify underlying mechanisms. PMID:27454174

  19. Emission reduction by multipurpose buffer strips on arable fields.

    PubMed

    Sloots, K; van der Vlies, A W

    2007-01-01

    In the area managed by Hollandse Delta, agriculture is under great pressure and the social awareness of the agricultural sector is increasing steadily. In recent years, a stand-still has been observed in water quality, in terms of agrochemicals, and concentrations even exceed the standard. To improve the waterquality a multi-purpose Field Margin Regulation was drafted for the Hoeksche Waard island in 2005. The regulation prescribes a crop-free strip, 3.5 m wide, alongside wet drainage ditches. The strip must be sown with mixtures of grasses, flowers or herbs. No crop protection chemicals or fertilizer may be used on the strips. A total length of approximately 200 km of buffer strip has now been laid. Besides reducing emissions, the buffer strips also stimulate natural pest control methods and encourage local tourism. Finally, the strips should lead to an improvement in the farmers' image. The regulation has proved to be successful. The buffer strips boosted both local tourism and the image of the agricultural sector. Above all, the strips provided a natural shield for emission to surface water, which will lead to an improvement of the water quality and raise the farmers' awareness of water quality and the environment. PMID:17711002

  20. Cell Electrosensitization Exists Only in Certain Electroporation Buffers.

    PubMed

    Dermol, Janja; Pakhomova, Olga N; Pakhomov, Andrei G; Miklavčič, Damijan

    2016-01-01

    Electroporation-induced cell sensitization was described as the occurrence of a delayed hypersensitivity to electric pulses caused by pretreating cells with electric pulses. It was achieved by increasing the duration of the electroporation treatment at the same cumulative energy input. It could be exploited in electroporation-based treatments such as electrochemotherapy and tissue ablation with irreversible electroporation. The mechanisms responsible for cell sensitization, however, have not yet been identified. We investigated cell sensitization dynamics in five different electroporation buffers. We split a pulse train into two trains varying the delay between them and measured the propidium uptake by fluorescence microscopy. By fitting the first-order model to the experimental results, we determined the uptake due to each train (i.e. the first and the second) and the corresponding resealing constant. Cell sensitization was observed in the growth medium but not in other tested buffers. The effect of pulse repetition frequency, cell size change, cytoskeleton disruption and calcium influx do not adequately explain cell sensitization. Based on our results, we can conclude that cell sensitization is a sum of several processes and is buffer dependent. Further research is needed to determine its generality and to identify underlying mechanisms. PMID:27454174

  1. Buffer layers on metal alloy substrates for superconducting tapes

    DOEpatents

    Jia, Quanxi; Foltyn, Stephen R.; Arendt, Paul N.; Groves, James R.

    2004-06-29

    An article including a substrate, a layer of an inert oxide material upon the surface of the substrate, a layer of an amorphous oxide or oxynitride material upon the inert oxide material layer, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the amorphous oxide material layer, and a layer of a SrRuO.sub.3 buffer material upon the oriented cubic oxide material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon the layer of a SrRuO.sub.3 buffer material layer. With a HTS top-layer of YBCO upon at least one layer of the SrRuO.sub.3 buffer material in such an article, J.sub.c 's of up to 1.3.times.10.sup.6 A/cm.sup.2 have been demonstrated with projected IC's of over 200 Amperes across a sample 1 cm wide.

  2. Bicarbonate Availability for Vocal Fold Epithelial Defense to Acidic Challenge

    PubMed Central

    Durkes, Abigail; Sivasankar, M. Preeti

    2014-01-01

    Objectives Bicarbonate is critical for acid-base tissue homeostasis. In this study we investigated the role of bicarbonate ion transport in vocal fold epithelial defense to acid challenges. Acidic insults to the larynx are common in gastric reflux, carcinogenesis and metastasis, and acute inflammation. Methods Ion transport was measured in viable, porcine vocal fold epithelium. First, 18 vocal folds were exposed to either the carbonic anhydrase antagonist acetazolamide or to vehicle. Second, 32 vocal folds were exposed to either a control buffer or a bicarbonate-free buffer on their luminal or basolateral surface or both. Third, vocal folds were challenged with acid in the presence of bicarbonate-free or control buffer. Results The vocal fold transepithelial resistance was greater than 300 Ω*cm2, suggesting robust barrier integrity. Ion transport did not change after exposure to acetazolamide (p > 0.05). Exposure to bicarbonate-free buffer did not compromise vocal fold ion transport (p > 0.05). Ion transport increased after acid challenge. This increase approached statistical significance and was the greatest for the control buffer and for the bicarbonate-free buffer applied to the basolateral surface. Conclusions Bicarbonate secretion may contribute to vocal fold defense against acid challenge. Our data offer a potential novel role for bicarbonate as a therapeutic agent to reduce pH abnormalities in the larynx and prevent associated pathological changes. PMID:24574427

  3. Inhibition of enamel demineralization by buffering effect of S-PRG filler-containing dental sealant.

    PubMed

    Kaga, Masayuki; Kakuda, Shinichi; Ida, Yusuke; Toshima, Hirokazu; Hashimoto, Masanori; Endo, Kazuhiko; Sano, Hidehiko

    2014-02-01

    The buffering capacity and inhibitory effects on enamel demineralization of two commercially available dental sealants were evaluated in this study. The effects of filler particles were also examined. Disks of enamel and cured sealant materials of BeautiSealant (silica or S-PRG filler) or Teethmate F-1 were incubated in lactic acid solutions (pH 4.0) for 1-6 d. The pH changes and amounts of ions released in the solutions were assessed, and enamel surfaces were observed using a scanning electron microscope. The pH of the solution with BeautiSealant (S-PRG filler) was neutralized from pH 4.0 to pH 6.1 (after incubation for 1 d) and from pH 4.0 to pH 6.7 (after incubation for 6 d). In addition, no release of calcium ions was detected and the enamel surface was morphologically intact in scanning electron microscopy images. However, the pH of the solution with Teethmate F-1 remained below pH 4.0 during incubation from days 1 to 6. Calcium release was increased in solutions up to and after 6 d of incubation. Scanning electron microscopy images showed that the structures of hydroxyapatite rods were exposed at the specimen surfaces as a result of demineralization. Ions released from S-PRG filler-containing dental sealant rapidly buffered the lactic acid solution and inhibited enamel demineralization. PMID:24372898

  4. [Bicarbonate instead of lactate buffered substitution solution for continuous hemofiltration in intensive care].

    PubMed

    Olbricht, C J; Huxmann-Nägeli, D; Bischoff, H

    1990-04-01

    The substitution fluids applied in continuous haemofiltration contain 40 mmol/l of lactate. This is unphysiological, since administration of large amounts of lactate lowers the phosphorylation potential and increases catabolism. With bicarbonate-buffered fluid three problems may arise: 1. Precipitation of calcium carbonate and magnesium carbonate; 2. pH is usually 8.4; 3. evaporation of CO2 increases pH. To solve these problems we applied a two-component system consisting of a glass bottle with 160 ml sodium bicarbonate 8.4% and a bag with 4.5 l of acidic solution. Prior to use, the bicarbonate was infused into the bag. The values of Ca++, Mg++, bicarbonate, and pH in this final substitution solution were constant during a 24 hr period after mixing. Precipitation of Ca++ and Mg++ carbonate was prevented by 3 mmol/l of lactic acid in the solution. The pH was 7.37. Evaporation of CO2 was prevented by bags made of special plastic sheeting. The solution was then applied in 7 intensive-care patients suffering from acute renal failure treated by continuous arteriovenous haemofiltration. No side effects of the solution were observed during six days of treatment. The values of Ca++, bicarbonate, pH, and pCO2 remained constant under clinical routine conditions. Hence, bicarbonate-buffered substitution solution is recommended for continuous haemofiltration. Continuous haemofiltration is now also available for patients with impaired liver function and increased lactate levels. PMID:2360710

  5. Wheeler County Riparian Buffers; 2002-2003 Annual Report.

    SciTech Connect

    Potter, Judy; Homer, Will

    2004-02-01

    Problems Encountered During Contract Year--Wheeler County residents are mostly non participants when it comes to Farm Services programs. Results of the counties non participation is the rental rates are the lowest in the state. There is a government fear factor as well as an obvious distance limitation. The FSA office is nearly 150 mile roundtrip from two of the counties urban areas. I find myself not only selling the CREP-Riparian Buffer but also selling Farm Services in general. Training has been very limited. NRCS is obviously not designed around training and certification. They are an on-the-job training organization. It has caused a hesitation in my outreach program and a great deal of frustration. I feel my confidence will strengthen with the follow through of the current projects. The most evident problem has come to light as of late. The program is too expensive to implement. The planting is too intensive for a 12''-18'' rainfall area. I provide the potential landowner a spread sheet with the bonuses, the costs, and the final outcome. No matter the situation, CREP or CCRP, the landowner always balks at the cost. The program assumes the landowner has the capital to make the initial investment. For example, project No.2 is going to be a minimum width buffer. It is approximately 3,000 ft long and 5.5 acres. The buffer for tree planting and fencing alone will result in a cost of nearly $13,000. With the water developments it nears $23,000. That is nearly 10% of a 250 mother-cow operating budget. Project No.1, the tree planting estimate is $45,000. This alone is nearly 25% of the same type of budget. I would greatly appreciate any help in finding a third party willing to put money to work covering the initial costs of the program, expecting reimbursement from Farm Services Agency. I believe this could create a powerful tool in buffering streams in Wheeler County. Outlook for Contract Year 2--I have been in this position now for 6 months. I am beginning to feel a

  6. High-buffering capacity, hydrolytically stable, low-pI isoelectric membranes for isoelectric trapping separations.

    PubMed

    Lalwani, Sanjiv; Shave, Evan; Vigh, Gyula

    2004-10-01

    Hydrolytically stable, low-pI isoelectric membranes have been synthesized from low-pI ampholytic components, poly(vinyl alcohol), and a bifunctional cross-linker, glycerol-1,3-diglycidyl ether. The low-pI ampholytic components used contain one amino group and at least two weakly acidic functional groups. The acidic functional groups are selected such that the pI value of the ampholytic component is determined by the pK(a) values of the acidic functional groups. When the concentration of the ampholytic component incorporated into the membrane is higher than a required minimum value, the pI of the membrane becomes independent of variations in the actual incorporation rate of the ampholytic compound. The new, low-pI isoelectric membranes have been successfully used as anodic membranes in isoelectric trapping separations with pH < 1.5 anolytes and replaced the hydrolytically less stable polyacrylamide-based isoelectric membranes. The new low-pI isoelectric membranes have excellent mechanical stability, low electric resistance, good buffering capacity, and long life time, even when used with as much as 50 W power and current densities as high as 33 mA/cm(2) during the isoelectric trapping separations. PMID:15490454

  7. On the delay analysis of a TDMA channel with finite buffer capacity

    NASA Technical Reports Server (NTRS)

    Yan, T.-Y.

    1982-01-01

    The throughput performance of a TDMA channel with finite buffer capacity for transmitting data messages is considered. Each station has limited message buffer capacity and has Poisson message arrivals. Message arrivals will be blocked if the buffers are congested. Using the embedded Markov chain model, the solution procedure for the limiting system-size probabilities is presented in a recursive fashion. Numerical examples are given to demonstrate the tradeoffs between the blocking probabilities and the buffer sizing strategy.

  8. Using nitrogen-15 to quantify vegetative buffer effectiveness for sequestering nitrogen in runoff.

    PubMed

    Bedard-Haughn, A; Tate, K W; van Kessel, C

    2004-01-01

    Previous studies have observed higher levels of soluble nutrients leaving vegetative buffers than entering them, suggesting that the buffers themselves are acting as a source rather than a sink by releasing previously stored nutrients. This study used 98 atom % (15)N-labeled KNO(3) at a rate of 5 kg ha(-1) to quantify buffer efficiency for sequestering new inputs of NO(-)(3)-N in an extensively grazed irrigated pasture system. Buffer treatments consisted of an 8-m buffer, a 16-m buffer, and a nonbuffered control. Regardless of the form of runoff N (NO(-)(3), NH(+)(4), or dissolved organic nitrogen [DON]), more (15)N was lost from the nonbuffered treatments than from the buffered treatments. The majority of the N attenuation was by vegetative uptake. Over the course of the study, the 8-m buffer decreased NO(-)(3)-(15)N load by 28% and the 16-m buffer decreased load by 42%. For NH(+)(4)-(15)N, the decrease was 34 and 48%, and for DON-(15)N, the decrease was 21 and 9%. Although the buffers were effective overall, the majority of the buffer impact occurred in the first four weeks after (15)N application, with the buffered plots attenuating nearly twice as much (15)N as the nonbuffered plots. For the remainder of the study, buffer effect was not as marked; there was a steady release of (15)N, particularly NO(-)(3)- and DON-(15)N, from the buffers into the runoff. This suggests that for buffers to be sustainable for N sequestration there is a need to manage buffer vegetation to maximize N demand and retention. PMID:15537948

  9. Improved labelling of DTPA- and DOTA-conjugated peptides and antibodies with 111In in HEPES and MES buffer

    PubMed Central

    2012-01-01

    Background In single photon emission computed tomography [SPECT], high specific activity of 111In-labelled tracers will allow administration of low amounts of tracer to prevent receptor saturation and/or side effects. To increase the specific activity, we studied the effect of the buffer used during the labelling procedure: NaAc, NH4Ac, HEPES and MES buffer. The effect of the ageing of the 111InCl3 stock and cadmium contamination, the decay product of 111In, was also examined in these buffers. Methods Escalating amounts of 111InCl3 were added to 1 μg of the diethylene triamine pentaacetic acid [DTPA]- and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid [DOTA]-conjugated compounds (exendin-3, octreotide and anti-carbonic anhydrase IX [CAIX] antibody). Five volumes of 2-(N-morpholino)ethanesulfonic acid [MES], 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid [HEPES], NH4Ac or NaAc (0.1 M, pH 5.5) were added. After 20 min at 20°C (DTPA-conjugated compounds), at 95°C (DOTA-exendin-3 and DOTA-octreotide) or at 45°C (DOTA-anti-CAIX antibody), the labelling efficiency was determined by instant thin layer chromatography. The effect of the ageing of the 111InCl3 stock on the labelling efficiency of DTPA-exendin-3 as well as the effect of increasing concentrations of Cd2+ (the decay product of 111In) were also examined. Results Specific activities obtained for DTPA-octreotide and DOTA-anti-CAIX antibody were five times higher in MES and HEPES buffer. Radiolabelling of DTPA-exendin-3, DOTA-exendin-3 and DTPA-anti-CAIX antibody in MES and HEPES buffer resulted in twofold higher specific activities than that in NaAc and NH4Ac. Labelling of DTPA-exendin-3 decreased with 66% and 73% for NaAc and NH4Ac, respectively, at day 11 after the production date of 111InCl3, while for MES and HEPES, the maximal decrease in the specific activity was 10% and 4% at day 11, respectively. The presence of 1 pM Cd2+ in the labelling mixture of DTPA-exendin-3 in NaAc and NH4Ac

  10. Modelling study on buffering pH and retaining U using a simplified uranium mill tailings pile example

    NASA Astrophysics Data System (ADS)

    Jacques, Diederik; Simunek, Jirka

    2014-05-01

    The hypothetical problem that is presented here considers the release and migration of uranium from a simplified uranium mill tailings pile towards a river. The modeling exercise with the coupled reactive transport model HP2 illustrates the effect of the geochemical conceptual model for sorption on (i) the buffering of the pH in the soil/aquifer system and (ii) the retention of U in the soil. The HP2 module, which couples the PHREEQC geochemical code with HYDRUS (2D/3D), is a two-dimensional equivalent of the one-dimensional HP1 program that was first released in 2005 (Jacques et al., 2008), and used successfully in many applications. Sorption of U is described using a multi-site cation exchange model (see Jacques et al., 2008). This sorption model also buffers the acid pH due to proton exchange. Two scenarios are considered: a soil with a relatively low (8.1 × 10-3 mol/kg) and relatively high (8.1 × 10-2 mol/kg) sorption capacity. In the third scenario, specific sorption of U and other cations and anions on Fe-oxides is described using a non-electrostatic surface complexation model with a very low capacity (8.1 × 10-4 mol/kg), in addition to low exchange complexation. Proton exchange on the cation exchanger buffers the acidity by replacing calcium with protons on the exchanger; the spatial extent of the pH-perturbed region is smaller in the scenario with the higher exchange capacity. Specific sorption has only a small effect on the pH-perturbed zone, although it is important to note that its capacity is one order of magnitude lower than in the scenario with the low sorption capacity. U reaches the river system within 1000 d in scenarios with low and high exchange capacities. Only in the scenario with specific sorption, U migration within the ground water system is retarded, compared to the other two cases. The results of the three scenarios do not seem to be intuitive, especially the equally fast movement of U in the scenario with a high exchange capacity

  11. Impact of buffer type on streamside nutrient concentrations in Upper Big Walnut Creek, Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The identification and assessment of conservation practices continues to be important for the protection of natural resources. Buffers, also referred to as filter strips, buffer strips, riparian buffers, or vegetative filters are one of the most common types of conservation practice installed in the...

  12. Analysis of microbial populations, denitrification, and nitrous oxide production in riparian buffers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian buffers are used extensively to protect water bodies from nonpoint source nitrogen pollution. However there is relatively little information on the impact of these buffers on production of nitrous oxide (N2O). In this study, we assessed nitrous oxide production in riparian buffers of the so...

  13. Spatial Patterns of Sediment and Phosphorus in a Riparian Buffer, Western Iowa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Riparian buffers prevent sediment and phosphorus (P) from reaching streams, however their accumulation in buffers is seldom measured. This study’s objectives were to determine accumulations of sediment and P in a multi-species riparian buffer, and spatial-temporal patterns of P in soil water and gro...

  14. A Review of Effectiveness of Vegetative Buffers on Sediment Trapping in Agricultural Areas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In recent years, there has been growing recognition of the importance of riparian buffers between agricultural fields and waterbodies. Riparian buffers play an important role in mitigating the impacts of land use activities on water quality and aquatic ecosystems. Riparian buffer systems have been...

  15. Classification of Orthophotos to Identify Vegetative Buffer Strips to Update Existing Land Use Databases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetative buffer strips (VBS) including grass buffer, forested buffer (FBS), among others, are important best management practices implemented in agricultural areas to control the movement of potential agricultural contaminants into water bodies. The importance of VBS has led the Natural Resource C...

  16. A VSA-based strategy for placing conservation buffers in agricultural watersheds.

    PubMed

    Qiu, Zeyuan

    2003-09-01

    Conservation buffers have the potential to reduce agricultural nonpoint source pollution and improve terrestrial wildlife habitat, landscape biodiversity, flood control, recreation, and aesthetics. Conservation buffers, streamside areas and riparian wetlands are being used or have been proposed to control agricultural nonpoint source pollution. This paper proposes an innovative strategy for placing conservation buffers based on the able source area (VSA) hydrology. VSAs are small, variable but predictable portion of a watershed that regularly contributes to runoff generation. The VSA-based strategy involves the following three steps: first, identifying VSAs in landscapes based on natural characteristics such as hydrology, land use/cover, topography and soils; second, targeting areas within VSAs for conservation buffers; third, refining the size and location of conservation buffers based on other factors such as weather, environmental objectives, available funding and other best management practices. Building conservation buffers in VSAs allows agricultural runoff to more uniformly enter buffers and stay there longer, which increases the buffer's capacity to remove sediments and nutrients. A field-scale example is presented to demonstrate the effectiveness and cost-effectiveness of the within-VSA conservation buffer scenario relative to a typical edge-of-field buffer scenario. The results enhance the understanding of hydrological processes and interactions between agricultural lands and conservation buffers in agricultural landscapes, and provide practical guidance for land resource managers and conservationists who use conservation buffers to improve water quality and amenity values of agricultural landscape. PMID:14753616

  17. Vegetative buffers for swine odor mitigation - wind tunnel evaluation of air flow dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetative buffers are a cost effective method to mitigate odor and particulate emissions from swine confined facilities. Establishment of vegetative buffers can be done prior to beginning operations, or during any given point in the lifetime of the swine facility. Design of vegetative buffers shoul...

  18. Atomically flat Ge buffer layers and alternating shutter growth of CaGe2 for large area germanane

    NASA Astrophysics Data System (ADS)

    Xu, Jinsong; Katoch, Jyoti; Ahmed, Adam; Pinchuk, Igor; Williams, Robert; McComb, David; Kawakami, Roland

    Germanane (GeH), which is converted from CaGe2 by soaking in HCl acid, has recently attracted interest because of its novel properties, such as large band gap (1.56eV), spin orbit coupling and predictions of high mobility (18000 cm2/Vs). Previously CaGe2 was successfully grown on Ge(111) substrates by molecular beam epitaxy (MBE) growth. But there were cracks between µm-sized islands, which is not desirable for scientific study and application, and limits the material quality. By growing atomically flat Ge buffer layers and using alternating shutter MBE growth, we are able to grow crack-free, large area films of CaGe2 films. Reflection high energy electron diffraction (RHEED) patterns of Ge buffer layer and CaGe2 indicates high quality two dimensional surfaces, which is further confirmed by atomic force microscopy (AFM), showing atomically flat and uniform Ge buffer layer and CaGe2. The appearance of Laue oscillation in X-ray diffraction (XRD) and Kiessig fringes in X-ray reflectivity (XRR) proves the uniformity of CaGe2 film and the smoothness of the interface. The high quality of CaGe2 film makes it promising to explore novel properties of GeH. Funded by NSF MRSEC DMR-1420451.

  19. Effects of the buffering capacity of the soil on the mobilization of heavy metals. Equilibrium and kinetics.

    PubMed

    Villen-Guzman, Maria; Paz-Garcia, Juan M; Amaya-Santos, Gema; Rodriguez-Maroto, Jose M; Vereda-Alonso, Carlos; Gomez-Lahoz, Cesar

    2015-07-01

    Understanding the possible pH-buffering processes is of maximum importance for risk assessment and remediation feasibility studies of heavy-metal contaminated soils. This paper presents the results about the effect of the buffering capacity of a polluted soil, rich in carbonates, on the pH and on the leaching evolution of its main contaminant (lead) when a weak acid (acetic acid) or a strong one (nitric acid) are slowly added. In both cases, the behavior of lead dissolution could be predicted using available (scientifically verified freeware) models assuming equilibrium between the solid and the aqueous phase. However, the experimental results indicate that the dissolution of calcium and magnesium carbonates is kinetically controlled. These kinetic limitations affect the overall behavior, and should be considered to understand also the response of the metals under local equilibrium. The well-known BCR sequential extraction procedure was used before- and after-treatment, to fractionate the lead concentration in the soil according to its mobility. The BCR results were also in agreement with the predictions of the equilibrium model. This agreement allows new insights about the information that could be derived from the BCR fractionation analysis. PMID:25781866

  20. Dynamic model and performance analysis of landing buffer for bionic locust mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Dian-Sheng; Zhang, Zi-Qiang; Chen, Ke-Wei

    2016-06-01

    The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is proposed. Given the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance, and it establishes a theoretical basis for studies and engineering applications.

  1. Dynamic model and performance analysis of landing buffer for bionic locust mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Dian-Sheng; Zhang, Zi-Qiang; Chen, Ke-Wei

    2015-10-01

    The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is proposed. Given the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance, and it establishes a theoretical basis for studies and engineering applications.

  2. Costs of Producing Biomass from Riparian Buffer Strips

    SciTech Connect

    Turhollow, A.

    2000-09-01

    Nutrient runoff from poultry litter applied to agricultural fields in the Delmarva Peninsula contributes to high nutrient loadings in Chesapeake Bay. One potential means of ameliorating this problem is the use of riparian buffer strips. Riparian buffer strips intercept overland flows of water, sediments, nutrients, and pollutants; and ground water flows of nutrients and pollutants. Costs are estimated for three biomass systems grown on buffer strips: willow planted at a density of 15,300 trees/ha (6200 trees/acre); poplar planted at a density of 1345 trees/ha (545 trees/acre); and switchgrass. These costs are estimated for five different scenarios: (1) total economic costs, where everything is costed [cash costs, noncash costs (e.g., depreciation), land rent, labor]; (2) costs with Conservation Reserve Program (CRP) payments (which pays 50% of establishment costs and an annual land rent); (3) costs with enhanced CRP payments (which pays 95% of establishment costs and an annual payment of approximately 170% of land rent for trees and 150% of land rent for grasses); (4) costs when buffer strips are required, but harvest of biomass is not required [costs borne by biomass are for yield enhancing activities (e.g., fertilization), harvest, and transport]; and (5) costs when buffer strips are required. and harvest of biomass is required to remove nutrients (costs borne by biomass are for yield enhancing activities and transport). CRP regulations would have to change to allow harvest. Delivered costs of willow, poplar, and switchgrass [including transportation costs of $0.38/GJ ($0.40/million Btu) for switchgrass and $0.57/GJ ($0.60/million Btu) for willow and poplar] at 11.2 dry Mg/ha-year (5 dry tons/acre-year) for the five cost scenarios listed above are [$/GJ ($million BIN)]: (1) 3.30-5.45 (3.45-5.75); (2) 2.30-3.80 (2.45-4.00); (3) 1.70-2.45 (1.80-2.60); (4) l-85-3.80 (1.95-4.05); and (5) 0.80-1.50 (0.85-1.60). At yields of 15.7 to 17.9 GJ/ha-year (7 to 8 dry tons

  3. Nacre surface transformation to hydroxyapatite in a phosphate buffer solution.

    PubMed

    Ni, Ming; Ratner, Buddy D

    2003-10-01

    Nacre, also known as mother-of-pearl, constitutes the inner layer of mollusc shells. Nacre is a natural composite material consisting mostly of calcium carbonate in the aragonite crystal form and some organic matter. Previous studies have shown that geological aragonite, coral and nacre can convert hydrothermally to hydroxyapatite (HAP) in phosphate solution by a solid-state topotactic ion-exchange reaction. This conversion typically occurs within the range of 140-260 degrees C, although higher temperatures are possible. In this work, we have found that nacre can transform to HAP in a phosphate buffer solution at room temperature via a surface reaction. The morphology of the nacre-transformed HAP surface was investigated by scanning electron microscopy (SEM). The HAP surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). A layer covered with packed particles was found in contrast to the tablet structure typical of nacre surfaces. XPS and SIMS indicated that the mineral phase of the nacre surface had converted from an aragonite phase to an HAP phase. Fourier transform infrared spectroscopy (FTIR) showed that phosphate (PO(4)) bands appeared after nacre was soaked in a phosphate buffer and the intensity of the PO(4) bands increased with exposure time. The FTIR was consistent with XPS and SIMS results. We suggest that this surface reaction occurs by a dissolution-precipitation mechanism. Calcium ions are released from the nacre surface, react with phosphate ions in the buffer solution, and then precipitate as HAP on the nacre surface. PMID:12853263

  4. New MBE (molecular beam epitaxy) buffer used to eliminate backgating in gaas mesfets

    SciTech Connect

    Smith, F.W.; Calawa, A.R.; Chen, C.L.; Manfra, M.J.; Mahoney, L.J.

    1988-02-01

    A new buffer layer has been developed that eliminates backgating between MESFET's fabricated in active layers grown upon it. The new buffer is grown by molecular beam epitaxy (MBE) at low substrate temperatures (150-300 C) using Ga and As4 beam fluxes. It is highly resistive, optically inactive, and crystalline, and high-quality GaAs active layers can be grown on top of the new buffer. MESFET's fabricated in active layers grown on top of this new buffer show improved output resistance and breakdown voltages; the dc and Rf characteristics are otherwise comparable to MESFET's fabricated by alternative means and with other buffer layers.

  5. Photo-induced wettability of TiO{sub 2} film with Au buffer layer

    SciTech Connect

    Purkayastha, Debarun Dhar; Sangani, L. D. Varma; Krishna, M. Ghanashyam; Madhurima, V.

    2014-04-24

    The effect of thickness of Au buffer layer (15-25 nm) between TiO{sub 2} film and substrate on the wettability of TiO{sub 2} films is reported. TiO{sub 2} films grown on Au buffer layer have a higher contact angle of 96-;100° as compared to 47.6o for the film grown without buffer layer. The transition from hydrophobicity to hydrophilicity under UV irradiation occurs within 10 min. for the buffer layered films whereas it is almost 30 min. for the film grown without buffer layer. The enhanced photo induced hydrophilicity is shown to be surface energy driven.

  6. Biomass carbon, nitrogen and phosphorus stocks in hybrid poplar buffers, herbaceous buffers and natural woodlots in the riparian zone on agricultural land.

    PubMed

    Fortier, Julien; Truax, Benoit; Gagnon, Daniel; Lambert, France

    2015-05-01

    In many temperate agricultural areas, riparian forests have been converted to cultivated land, and only narrow strips of herbaceous vegetation now buffer many farm streams. The afforestation of these riparian zones has the potential to increase carbon (C) storage in agricultural landscapes by creating a new biomass sink for atmospheric CO2. Occurring at the same time, the storage of nitrogen (N) and phosphorus (P) in plant biomass, is an important water quality function that may greatly vary with types of riparian vegetation. The objectives of this study were (1) to compare C, N and P storage in aboveground, belowground and detrital biomass for three types of riparian vegetation cover (9-year-old hybrid poplar buffers, herbaceous buffers and natural woodlots) across four agricultural sites and (2) to determine potential vegetation cover effects on soil nutrient supply rate in the riparian zone. Site level comparisons suggest that 9-year-old poplar buffers have stored 9-31 times more biomass C, 4-10 times more biomass N, and 3-7 times more biomass P than adjacent non managed herbaceous buffers, with the largest differences observed on the more fertile sites. The conversion of these herbaceous buffers to poplar buffers could respectively increase C, N and P storage in biomass by 3.2-11.9 t/ha/yr, 32-124 kg/ha/yr and 3.2-15.6 kg/ha/yr, over 9 years. Soil NO3 and P supply rates during the summer were respectively 57% and 66% lower in poplar buffers than in adjacent herbaceous buffers, potentially reflecting differences in nutrient storage and cycling between the two buffer types. Biomass C ranged 49-160 t/ha in woodlots, 33-110 t/ha in poplar buffers and 3-4 t/ha in herbaceous buffers. Similar biomass C stocks were found in the most productive poplar buffer and three of the four woodlots studied. Given their large and varied biomass C stocks, conservation of older riparian woodlots is equally important for C balance management in farmland. In addition, the

  7. Generating soft shadows with a depth buffer algorithm

    NASA Technical Reports Server (NTRS)

    Brotman, L. S.; Badler, N. I.

    1984-01-01

    Computer-synthesized shadows used to appear with a sharp edge when cast onto a surface. At present the production of more realistic, soft shadows is considered. However, significant costs arise in connection with such a representation. The current investigation is concerned with a pragmatic approach, which combines an existing shadowing method with a popular visible surface rendering technique, called a 'depth buffer', to generate soft shadows resulting from light sources of finite extent. The considered method represents an extension of Crow's (1977) shadow volume algorithm.

  8. Interaction of ICT receptor with serum albumins in aqueous buffer

    NASA Astrophysics Data System (ADS)

    Wu, Fang-Ying; Ji, Zhao-Jun; Wu, Yu-Mei; Wan, Xiao-Fen

    2006-06-01

    A novel compound, p-(dimethylamino)benzamido-thiosemicarbazide ( 1), based on intramolecular charge transfer fluorescence was synthesized. In pH 7.4 Tris-HCl buffer, the emission intensity of 1 increased upon the addition of HSA or BSA due to the energy transfer from the protein to 1 and also the hydrophobic microenvironment provided by HSA or BSA. The binding constants between 1 and proteins were 1.41 × 10 5 mol -1 L for HSA and 8.68 × 10 4 mol -1 L for BSA, respectively. There is only one binding site. The interaction between 1 and proteins was further investigated by synchronous fluorescence.

  9. Buffer thermal energy storage for a solar Brayton engine

    NASA Technical Reports Server (NTRS)

    Strumpf, H. J.; Barr, K. P.

    1981-01-01

    A study has been completed on the application of latent-heat buffer thermal energy storage to a point-focusing solar receiver equipped with an air Brayton engine. To aid in the study, a computer program was written for complete transient/stead-state Brayton cycle performance. The results indicated that thermal storage can afford a significant decrease in the number of engine shutdowns as compared to operating without thermal storage. However, the number of shutdowns does not continuously decrease as the storage material weight increases. In fact, there appears to be an optimum weight for minimizing the number of shutdowns.

  10. Conductive and robust nitride buffer layers on biaxially textured substrates

    DOEpatents

    Sankar, Sambasivan [Chicago, IL; Goyal, Amit [Knoxville, TN; Barnett, Scott A [Evanston, IL; Kim, Ilwon [Skokie, IL; Kroeger, Donald M [Knoxville, TN

    2009-03-31

    The present invention relates to epitaxial, electrically conducting and mechanically robust, cubic nitride buffer layers deposited epitaxially on biaxially textured substrates such as metals and alloys. The invention comprises of a biaxially textured substrate with epitaxial layers of nitrides. The invention also discloses a method to form such epitaxial layers using a high rate deposition method as well as without the use of forming gases. The invention further comprises epitaxial layers of oxides on the biaxially textured nitride layer. In some embodiments the article further comprises electromagnetic devices which may have superconducting properties.

  11. Conductive and robust nitride buffer layers on biaxially textured substrates

    DOEpatents

    Sankar, Sambasivan; Goyal, Amit; Barnett, Scott A.; Kim, Ilwon; Kroeger, Donald M.

    2004-08-31

    The present invention relates to epitaxial, electrically conducting and mechanically robust, cubic nitride buffer layers deposited epitaxially on biaxially textured substrates such as metal and alloys. The invention comprises of a biaxially textured substrate with epitaxial layers of nitrides. The invention also discloses a method to form such epitaxial layers using a high rate deposition method as well as without the use of forming gases. The invention further comprises epitaxial layers of oxides on the biaxially textured nitride layers. In some embodiments the article further comprises electromagnetic devices which may be super conducting properties.

  12. Controlled Chemical Doping of Semiconductor Nanocrystals Using Redox Buffers

    SciTech Connect

    Engel, Jesse H.; Surendranath, Yogesh; Alivisatos, Paul

    2013-07-20

    Semiconductor nanocrystal solids are attractive materials for active layers in next-generation optoelectronic devices; however, their efficient implementation has been impeded by the lack of precise control over dopant concentrations. Herein we demonstrate a chemical strategy for the controlled doping of nanocrystal solids under equilibrium conditions. Exposing lead selenide nanocrystal thin films to solutions containing varying proportions of decamethylferrocene and decamethylferrocenium incrementally and reversibly increased the carrier concentration in the solid by 2 orders of magnitude from their native values. This application of redox buffers for controlled doping provides a new method for the precise control of the majority carrier concentration in porous semiconductor thin films.

  13. Ge growth on porous silicon: The effect of buffer porosity on the epilayer crystalline quality

    NASA Astrophysics Data System (ADS)

    Calabrese, G.; Baricordi, S.; Bernardoni, P.; De Salvador, D.; Ferroni, M.; Guidi, V.; Morandi, V.; Vincenzi, D.

    2014-09-01

    We report on the epitaxial growth of Ge virtual substrates directly on Si (001) and on different porosity porous silicon (pSi) buffers. Obtained results indicate that Ge grown on low porosity (22%) pSi buffer has a better crystalline quality compared to Ge grown on bulk Si and on higher porosity buffers. This result is attributed to the compliant nature of pSi and to its reduced Young's modulus, which leads to plastic tensile deformation of the 22% porosity buffer under the in-plane tensile stress introduced by Ge lattice. The same result is not observed for higher porosity buffers, this effect being attributed to the higher buffer fragility. A low porosity pSi layer can hence be used as buffer for the growth of Ge on Si virtual substrates with reduced dislocation content and for the growth of Ge based devices or the successive integration of III-V semiconductors on Si.

  14. Leakage effects in n-GaAs MESFET with n-GaAs buffer layer

    NASA Technical Reports Server (NTRS)

    Wang, Y. C.; Bahrami, M.

    1983-01-01

    Whereas improvement of the interface between the active layer and the buffer layer has been demonstrated, the leakage effects can be important if the buffer layer resistivity is not sufficiently high and/or the buffer layer thickness is not sufficiently small. It was found that two buffer leakage currents exist from the channel under the gate to the source and from drain to the channel in addition to the buffer leakage resistance between drain and source. It is shown that for a 1 micron gate-length n-GaAs MESFET, if the buffer layer resistivity is 12 OHM-CM and the buffer layer thickness h is 2 microns, the performance of the device degrades drastically. It is suggested that h should be below 2 microns.

  15. An assessment of buffer strips for improving damage tolerance of composite laminates at elevated temperature

    NASA Technical Reports Server (NTRS)

    Bigelow, C. A.

    1981-01-01

    Buffer strips greatly improve the damage tolerance of graphite/epoxy laminates loaded in tension. Graphite/polyimide buffer strip panels were made and tested to determine their residual strength at ambient and elevated (177 C) temperature. Each panel was cut in the center to represent damage. Panels were radiographed and crack-opening displacements were recorded to indicate fracture, fracture arrest, and the extent of damage in the buffer strip after arrest. All panels had the same buffer strip spacing and width. The buffer strip material was 0 deg S-glass/PMR-15. The buffer strips were made by replacing narrow strips of the 0 deg graphite plies with strips of the 0 deg S-glass on either a one-for-one or a two-for-one basis. Half of the panels were heated to 177 + or - 3 C before and during the testing. Elevated temperature did not alter the fracture behavior of the buffer configuration.

  16. Performance Enhancement of Small Molecular Solar Cells by Bilayer Cathode Buffer.

    PubMed

    Sun, Qinjun; Zhao, Huanbin; Zhou, Miao; Gao, Liyan; Hao, Yuying

    2016-04-01

    An effective composite bilayer cathode buffer structure is proposed for use in small molecular solar cells. CsF was doped in Alq3 to form the first cathode buffer, leading to small serial resistances. BCP was used as the second cathode buffer to block the holes to the electrode. The optimized bilayer cathode buffer significantly increased the short circuit and fill factor of devices. By integrating this bilayer cathode buffer, the CuPc/C60 small molecular heterojunction cell exhibited a power conversion efficiency of up to 0.8%, which was an improvement of 56% compared to a device with only the Alq3 cathode buffer. Meanwhile, the bilayer cathode buffer still has a good protective effect on the performance of the device. PMID:27451719

  17. Wheeler County Riparian Buffers; 2004-2005 Annual Report.

    SciTech Connect

    Greer, Sue

    2006-01-01

    Number of Contacts Made--Over 44 landowner contacts were made regarding CREP potential. Out of those 44 contacts, 15 resulted in on-site visits to the property to discuss available options. Articles were published in the Wheeler SWCD annual report and newsletter totaling a distribution of 1,200. Two informational displays were viewed by approximately 500 people: one at the Wheeler SWCD Annual Meeting and the second at the Wheeler County Fair. Number of Contracts Negotiated and Signed--3 CREP contracts in Wheeler County were signed within this contract period. They included landowners on Stephenson Creek, Bear Creek and Lost Valley Creek. The project done on Lost Valley Creek was handled by the Gilliam Co. Riparian Buffer Specialist filling in during the Wheeler position being vacated. Work was also started and is proceeding on another four contracts. Problems Encountered During Contract Year: (1) Riparian Buffer position vacated in October 2004 and District had difficulty filling the position. This set the district back in some of the delineated goals. Existing district staff is now up-to-speed on training, etc. and District is confident of achieving outlined goals. (2) Issues involving qualification of irrigated rates and how to process irrigated acres through CREP. (3) Issues involving clarification of eligibility as it relates to financial status of landowner; and (4) Landowner comfort in signing up for federal programs.

  18. Ginkgo biloba extract: cognitive enhancer or antistress buffer.

    PubMed

    Ward, Christopher P; Redd, Kacy; Williams, Beverly M; Caler, Jeffrey R; Luo, Yuan; McCoy, John G

    2002-07-01

    Constituents extracted from the leaves of the Ginkgo biloba tree possess beneficial properties that may buffer the aging nervous system from deterioration due to oxidative stress. In the present investigation, a standardized extract of G. biloba (EGb 761) or an equal volume of the vehicle was administered (100 mg/kg/day) to senescent (20-month) C57BL/6 male mice for up to 82 consecutive days. Animals were tested twice in the Morris water maze (MWM) after 28 and 70 days of treatment. No differences were observed in acquisition or retention of performance on the water maze. Elevated-plus maze (EPM) trials were conducted prior to and subsequent to the chronic treatment regimen. Marked baseline differences in plus-maze performance were present in the first experiment. A second experiment used a matched-pairs design to minimize preexisting differences. Results supported the hypothesis that EGb 761 may serve as an antistress buffer, attenuating the increase in anxiety typically observed in animals after cold water exposure. Tissue samples from the hippocampus and cortex were analyzed by Western blot for the transcription factor cyclic-AMP response element binding (CREB) protein. EGb 761 had no significant effect on immunoreactivity to CREB from either the hippocampus or the cerebral cortex. PMID:12062581

  19. Buffer capacity, ecosystem feedbacks, and seawater chemistry under global change

    NASA Astrophysics Data System (ADS)

    Jury, C. P.; Thomas, F. I.; Atkinson, M. J.; Jokiel, P. L.; Onuma, M. A.; Kaku, N.; Toonen, R. J.

    2013-12-01

    Ocean acidification (OA) results in reduced seawater pH and aragonite saturation state (Ωarag), but also reduced seawater buffer capacity. As buffer capacity decreases, diel variation in seawater chemistry increases. However, a variety of ecosystem feedbacks can modulate changes in both average seawater chemistry and diel seawater chemistry variation. Here we model these effects for a coastal, reef flat ecosystem. We show that an increase in offshore pCO2 and temperature (to 900 μatm and +3°C) can increase diel pH variation by as much as a factor of 2.5 and can increase diel pCO2 variation by a factor of 4.6, depending on ecosystem feedbacks and seawater residence time. Importantly, these effects are different between day and night. With increasing seawater residence time and increasing feedback intensity, daytime seawater chemistry becomes more similar to present-day conditions while nighttime seawater chemistry becomes less similar to present-day conditions. Better constraining ecosystem feedbacks under global change will improve projections of coastal water chemistry, but this study shows the importance of considering changes in both average carbonate chemistry and diel chemistry variation for organisms and ecosystems. Further, we will discuss our recent work examining the effects of diel seawater chemistry variation on coral calcification rates.

  20. The Buffer Diagnostic Prototype: A fault isolation application using CLIPS

    NASA Technical Reports Server (NTRS)

    Porter, Ken

    1994-01-01

    This paper describes problem domain characteristics and development experiences from using CLIPS 6.0 in a proof-of-concept troubleshooting application called the Buffer Diagnostic Prototype. The problem domain is a large digital communications subsystems called the real-time network (RTN), which was designed to upgrade the launch processing system used for shuttle support at KSC. The RTN enables up to 255 computers to share 50,000 data points with millisecond response times. The RTN's extensive built-in test capability but lack of any automatic fault isolation capability presents a unique opportunity for a diagnostic expert system application. The Buffer Diagnostic Prototype addresses RTN diagnosis with a multiple strategy approach. A novel technique called 'faulty causality' employs inexact qualitative models to process test results. Experimental knowledge provides a capability to recognize symptom-fault associations. The implementation utilizes rule-based and procedural programming techniques, including a goal-directed control structure and simple text-based generic user interface that may be reusable for other rapid prototyping applications. Although limited in scope, this project demonstrates a diagnostic approach that may be adapted to troubleshoot a broad range of equipment.

  1. Mindfulness buffers retaliatory responses to injustice: A regulatory approach.

    PubMed

    Long, Erin Cooke; Christian, Michael S

    2015-09-01

    We investigate the role of mindfulness as a regulatory factor by examining whether it mitigates the relationship between justice and retaliation. Drawing on theories of self-regulation, we integrate work on justice with emerging frameworks that identify mindfulness as an important work-related regulatory variable (Glomb, Duffy, Bono, & Yang, 2011). Specifically, we identify the role of mindfulness as a buffer of the ruminative thoughts and negative emotions that link injustice to retaliation. We test mediated moderation hypotheses in 2 samples. In Sample 1, two behavioral measures of retaliation are assessed in an experiment that manipulated both injustice and mindfulness. In Sample 2, we generalize our model to the field, examining employee responses regarding experiences with workplace injustice and retaliation. Results of both studies converge to support the proposed mediated moderation model that mindfulness buffers the effect of injustice on rumination and negative emotions, thus reducing retaliation. Our findings contribute to the broader literatures on self-regulation, organizational justice, and retaliation. PMID:25751750

  2. Transient response of a thermal buffer: a study for ISABELLE

    SciTech Connect

    Schneider. W.J.

    1981-01-01

    Operation of the superconducting magnets in ISABELLE may necessitate rapid cooldown and warmup from ambient (300K) to liquid helium temperature (3K) to meet the requirements of the experimental program. Similarly, unprogrammed temperature excursions can also occur due to operator error or equipment malfunction. The coal bore tube of the magnets has a small mass relative to the more massive iron laminations and the stainless steel support tube. In addition the magnet coil, in thermal contact with the cold bore tube, has excellent heat transfer to the helium flowing through it compared to the iron mass. These two factors, mass and heat transfer, dictate that the cold bore tube will follow the temperature of the coolant more closely than the iron and hence substantial temperature gradients can exist. If the temperature difference between the coolant and the iron in the magnet exceeds 44K stress failure may occur to either the cold bore tube or the magnet dewar end cap. To preclude such failures from occuring at least two options are available. One method is to modify the magnet design by introducing flexibility between the bore tube and the end plate. Another is to introduce an insensitive thermal mass or buffer as has been suggested by Shutt, at the inlet of a sextant ahead of the first magnets. This paper describes the latter method, the design and transient response of a buffer during cooldown.

  3. Buffer layers on rolled nickel or copper as superconductor substrates

    DOEpatents

    Paranthaman, Mariappan; Lee, Dominic F.; Kroeger, Donald M.; Goyal, Amit

    2000-01-01

    Buffer layer architectures are epitaxially deposited on biaxially-textured rolled substrates of nickel and/or copper and their alloys for high current conductors, and more particularly buffer layer architectures such as Y.sub.2 O.sub.3 /Ni, YSZ/Y.sub.2 O.sub.3 /Ni, Yb.sub.2 O.sub.3 /Ni, Yb.sub.2 O.sub.3 /Y.sub.2 O.sub.3 /Ni, Yb.sub.2 O.sub.3 /CeO.sub.2 /Ni, RE.sub.2 O.sub.3 /Ni (RE=Rare Earth), and Yb.sub.2 O.sub.3 /YSZ/CeO.sub.2 /Ni, Y.sub.2 O.sub.3 /Cu, YSZ/Y.sub.2 O.sub.3 /Cu, Yb.sub.2 O.sub.3 /Cu, Yb.sub.2 O.sub.3 /Y.sub.2 O.sub.3 /Cu, Yb.sub.2 O.sub.3 /CeO.sub.2 /Cu, RE.sub.2 O.sub.3 /Cu, and Yb.sub.2 O.sub.3 /YSZ/CeO.sub.2 /Cu. Deposition methods include physical vapor deposition techniques which include electron-beam evaporation, rf magnetron sputtering, pulsed laser deposition, thermal evaporation, and solution precursor approach, which includes chemical vapor deposition, combustion CVD, metal-organic decomposition, sol-gel processing, and plasma spray.

  4. Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators*

    SciTech Connect

    A.T. Wu, S. Jin, J.D. Mammosser, C.E. Reece, R.A. Rimmer,L. Lin, X.Y. Lu, K. Zhao

    2011-09-01

    Niobium (Nb) is the most popular material that has been employed for making superconducting radio frequency (SRF) cavities to be used in various particle accelerators over the last couple of decades. One of the most important steps in fabricating Nb SRF cavities is the final chemical removal of 150 {mu}m of Nb from the inner surfaces of the SRF cavities. This is usually done by either buffered chemical polishing (BCP) or electropolishing (EP). Recently a new Nb surface treatment technique called buffered electropolishing (BEP) has been developed at Jefferson Lab. It has been demonstrated that BEP can produce the smoothest surface finish on Nb ever reported in the literature while realizing a Nb removal rate as high as 10 {mu}m/min that is more than 25 and 5 times quicker than those of EP and BCP(112) respectively. In this contribution, recent advance in optimizing and understanding BEP treatment technique is reviewed. Latest results from RF measurements on BEP treated Nb single cell cavities by our unique vertical polishing system will be reported.

  5. The Effects of Acetate Buffer Concentration on Lysozyme Solubility

    NASA Technical Reports Server (NTRS)

    Forsythe, Elizabeth L.; Pusey, Marc L.

    1996-01-01

    The micro-solubility column technique was employed to systematically investigate the effects of buffer concentration on tetragonal lysozyme solubility. While keeping the NaCl concentrations constant at 2%, 3%, 4%, 5% and 7%, and the pH at 4.0, we have studied the solubility of tetragonal lysozyme over an acetate buffer concentration range of 0.01M to 0.5M as a function of temperature. The lysozyme solubility decreased with increasing acetate concentration from 0.01M to 0.1M. This decrease may simply be due to the net increase in solvent ionic strength. Increasing the acetate concentration beyond 0.1M resulted in an increase in the lysozyme solubility, which reached a peak at - 0.3M acetate concentration. This increase was believed to be due to the increased binding of acetate to the anionic binding sites of lysozyme, preventing their occupation by chloride. In keeping with the previously observed reversal of the Hoffmeister series for effectiveness of anions in crystallizing lysozyme, acetate would be a less effective precipitant than chloride. Further increasing the acetate concentration beyond 0.3M resulted in a subsequent gradual decrease in the lysozyme solubility at all NaCl concentrations.

  6. Transition metal oxide as anode interface buffer for impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Tang, Chao; Wang, Xu-Liang; Zhai, Wen-Juan; Liu, Rui-Lan; Rong, Zhou; Pang, Zong-Qiang; Jiang, Bing; Fan, Qu-Li; Huang, Wei

    2015-12-01

    Impedance spectroscopy is a strong method in electric measurement, which also shows powerful function in research of carrier dynamics in organic semiconductors when suitable mathematical physical models are used. Apart from this, another requirement is that the contact interface between the electrode and materials should at least be quasi-ohmic contact. So in this report, three different transitional metal oxides, V2O5, MoO3 and WO3 were used as hole injection buffer for interface of ITO/NPB. Through the impedance spectroscopy and PSO algorithm, the carrier mobilities and I-V characteristics of the NPB in different devices were measured. Then the data curves were compared with the single layer device without the interface layer in order to investigate the influence of transitional metal oxides on the carrier mobility. The careful research showed that when the work function (WF) of the buffer material was just between the work function of anode and the HOMO of the organic material, such interface material could work as a good bridge for carrier injection. Under such condition, the carrier mobility measured through impedance spectroscopy should be close to the intrinsic value. Considering that the HOMO (or LUMO) of most organic semiconductors did not match with the work function of the electrode, this report also provides a method for wide application of impedance spectroscopy to the research of carrier dynamics.

  7. Reaction of nerve agents with phosphate buffer at pH 7.

    PubMed

    Creasy, William R; Fry, Roderick A; McGarvey, David J

    2012-07-12

    Chemical weapon nerve agents, including isopropyl methylphosphonofluoridate (GB or Sarin), pinacolyl methylphosphonofluoridate (GD or Soman), and S-(2-diisopropylaminoethyl) O-ethyl methylphosphonothioate (VX), are slow to react in aqueous solutions at midrange pH levels. The nerve agent reactivity increases in phosphate buffer at pH 7, relative to distilled water or acetate buffer. Reactions were studied using (31)P NMR. Phosphate causes faster reaction to the corresponding alkyl methylphosphonic acids, and produces a mixed phosphate/phosphonate compound as an intermediate reaction product. GB has the fastest reaction rate, with a bimolecular rate constant of 4.6 × 10(-3) M(-1)s(-1)[PO(4)(3-)]. The molar product branching ratio of GB acid to the pyro product (isopropyl methylphosphonate phosphate anhydride) is 1:1.4, independent of phosphate concentration, and the pyro product continues to react much slower to form GB acid. The pyro product has two doublets in the (31)P NMR spectrum. The rate of reaction for GD is slower than GB, with a rate constant of 1.26 × 10(-3) M(-1)s(-1) [PO(4)(3-)]. The rate for VX is considerably slower, with a rate constant of 1.39 × 10(-5) M(-1)s(-1) [PO(4)(3-)], about 2 orders of magnitude slower than the rate for GD. The rate constant of the reaction of GD with pyrophosphate at pH 8 is 2.04 × 10(-3) min(-1) at a concentration of 0.0145 M. The rate of reaction for diisopropyl fluorophosphate is 2.84 × 10(-3) min(-1) at a concentration of 0.153 M phosphate, a factor of 4 slower than GD and a factor of 15 slower than GB, and there is no detectable pyro product. The half-lives of secondary reaction of the GB pyro product in 0.153 and 0.046 M solution of phosphate are 23.8 and 28.0 h, respectively, which indicates little or no dependence on phosphate. PMID:22667763

  8. Wheeler County Riparian Buffers; 2003-2004 Annual Report.

    SciTech Connect

    Homer, Will

    2006-01-01

    Number of Contacts Made--I have contacted 35 landowners in Wheeler County. Of the 35 contacts 12 have resulted in meeting on their property to discuss available options. Included an article in the Annual Report and Wheeler SWCD newsletter mailed to 550 landowners. Contacts are primarily through networking with others here in the office as well as working closely with the NRCS office. Number of Contracts Negotiated--This Project has produced five riparian buffers within the past contract year. Each has greater meaning to the landowner than simply a buffer. In most cases the buffer is providing the landowner with improved grazing management and/or more reliable water source for livestock. Landowners also feel the enhanced wildlife habitat is a bonus to the program. Other Accomplishments--I took part in the John Day Subbasin Planning process and was able to offer assistance into the inventory items related to Wheeler County. I was often the only local representative able to attend the meetings. I assisted the Wheeler SWCD in writing a successful OWEB grant to remove 110 acres of junipers for watershed restoration, range rehabilitation, and economic development. One partner in the project is a manufacturer that uses juniper as their primary construction material. The goal is to create a pilot project that may grow into a self sustaining industry within the county. I also assisted in writing a small grant to improve water usage in the Muddy Creek watershed. I assisted with the Pine Creek Conservation Area ''Twilight Tour'' as well as the Wheeler SWCD ''Annual Meeting and Dinner''. Both events were successful in getting information out about our riparian buffer program. Facilitate office training and utilization of advanced GIS technology and mapping. Problems Encountered During Contract Year--The NRCS Cultural Resources Review process has ground to a halt. It is takes 6 months to get initial results from the Portland offices. Nearly all requests require site surveys

  9. Extracellular ATP hydrolysis inhibits synaptic transmission by increasing ph buffering in the synaptic cleft.

    PubMed

    Vroman, Rozan; Klaassen, Lauw J; Howlett, Marcus H C; Cenedese, Valentina; Klooster, Jan; Sjoerdsma, Trijntje; Kamermans, Maarten

    2014-05-01

    Neuronal computations strongly depend on inhibitory interactions. One such example occurs at the first retinal synapse, where horizontal cells inhibit photoreceptors. This interaction generates the center/surround organization of bipolar cell receptive fields and is crucial for contrast enhancement. Despite its essential role in vision, the underlying synaptic mechanism has puzzled the neuroscience community for decades. Two competing hypotheses are currently considered: an ephaptic and a proton-mediated mechanism. Here we show that horizontal cells feed back to photoreceptors via an unexpected synthesis of the two. The first one is a very fast ephaptic mechanism that has no synaptic delay, making it one of the fastest inhibitory synapses known. The second one is a relatively slow (τ≈200 ms), highly intriguing mechanism. It depends on ATP release via Pannexin 1 channels located on horizontal cell dendrites invaginating the cone synaptic terminal. The ecto-ATPase NTPDase1 hydrolyses extracellular ATP to AMP, phosphate groups, and protons. The phosphate groups and protons form a pH buffer with a pKa of 7.2, which keeps the pH in the synaptic cleft relatively acidic. This inhibits the cone Ca²⁺ channels and consequently reduces the glutamate release by the cones. When horizontal cells hyperpolarize, the pannexin 1 channels decrease their conductance, the ATP release decreases, and the formation of the pH buffer reduces. The resulting alkalization in the synaptic cleft consequently increases cone glutamate release. Surprisingly, the hydrolysis of ATP instead of ATP itself mediates the synaptic modulation. Our results not only solve longstanding issues regarding horizontal cell to photoreceptor feedback, they also demonstrate a new form of synaptic modulation. Because pannexin 1 channels and ecto-ATPases are strongly expressed in the nervous system and pannexin 1 function is implicated in synaptic plasticity, we anticipate that this novel form of synaptic

  10. Mono- and polyprotic buffer systems in anion exchange chromatography of influenza virus particles.

    PubMed

    Vajda, Judith; Weber, Dennis; Stefaniak, Sabine; Hundt, Boris; Rathfelder, Tanja; Müller, Egbert

    2016-05-27

    Different ions typically used in downstream processing of biologicals are evaluated for their potential in anion exchange chromatography of an industrially produced, pandemic influenza H1N1 virus. Capacity, selectivity and recovery are investigated based on single step elution parallel chromatography experiments. The inactivated H1N1 feedstream is produced in Madin-Darby Bovine Kidney cells. Interesting effects are found for sodium phosphate and sodium citrate. Both anions are triprotic kosmotropes. Anion exchange chromatography generally offers high scalability to satisfy sudden demands for vaccines, which may occur in case of an emerging influenza outbreak. Appropriate pH conditions for H1N1 adsorption are determined by Zeta potential measurements. The dynamic binding capacity of a salt tolerant polyamine-type resin is up to 6.4 times greater than the capacity of a grafted Q-type resin. Pseudo-affinity interactions of polyamines with the M2 protein of influenza may contribute to the obtained capacity increase. Both resins achieve greater capacity in sodium phosphate buffer compared to Tris/HCl. A recovery of 67% and DNA clearance close to 100% without DNAse treatment are achieved for the Q-type resin. Recovery of the virus from the salt tolerant resin requires the use of polyprotic acids in the elution buffer. 85% of the DNA and 60% of the proteins can be removed by the salt tolerant resin. The presence of sodium phosphate during anion exchange chromatography seems to support stability of the H1N1 particles in presence of hydrophobic cations. PMID:27130581

  11. Extracellular ATP Hydrolysis Inhibits Synaptic Transmission by Increasing pH Buffering in the Synaptic Cleft

    PubMed Central

    Vroman, Rozan; Klaassen, Lauw J.; Howlett, Marcus H.C.; Cenedese, Valentina; Klooster, Jan; Sjoerdsma, Trijntje; Kamermans, Maarten

    2014-01-01

    Neuronal computations strongly depend on inhibitory interactions. One such example occurs at the first retinal synapse, where horizontal cells inhibit photoreceptors. This interaction generates the center/surround organization of bipolar cell receptive fields and is crucial for contrast enhancement. Despite its essential role in vision, the underlying synaptic mechanism has puzzled the neuroscience community for decades. Two competing hypotheses are currently considered: an ephaptic and a proton-mediated mechanism. Here we show that horizontal cells feed back to photoreceptors via an unexpected synthesis of the two. The first one is a very fast ephaptic mechanism that has no synaptic delay, making it one of the fastest inhibitory synapses known. The second one is a relatively slow (τ≈200 ms), highly intriguing mechanism. It depends on ATP release via Pannexin 1 channels located on horizontal cell dendrites invaginating the cone synaptic terminal. The ecto-ATPase NTPDase1 hydrolyses extracellular ATP to AMP, phosphate groups, and protons. The phosphate groups and protons form a pH buffer with a pKa of 7.2, which keeps the pH in the synaptic cleft relatively acidic. This inhibits the cone Ca2+ channels and consequently reduces the glutamate release by the cones. When horizontal cells hyperpolarize, the pannexin 1 channels decrease their conductance, the ATP release decreases, and the formation of the pH buffer reduces. The resulting alkalization in the synaptic cleft consequently increases cone glutamate release. Surprisingly, the hydrolysis of ATP instead of ATP itself mediates the synaptic modulation. Our results not only solve longstanding issues regarding horizontal cell to photoreceptor feedback, they also demonstrate a new form of synaptic modulation. Because pannexin 1 channels and ecto-ATPases are strongly expressed in the nervous system and pannexin 1 function is implicated in synaptic plasticity, we anticipate that this novel form of synaptic modulation

  12. Aluminum elution and precipitation in glass vials: effect of pH and buffer species.

    PubMed

    Ogawa, Toru; Miyajima, Makoto; Wakiyama, Naoki; Terada, Katsuhide

    2015-02-01

    Inorganic extractables from glass vials may cause particle formation in the drug solution. In this study, the ability of eluting Al ion from borosilicate glass vials, and tendencies of precipitation containing Al were investigated using various pHs of phosphate, citrate, acetate and histidine buffer. Through heating, all of the buffers showed that Si and Al were eluted from glass vials in ratios almost the same as the composition of borosilicate glass, and the amounts of Al and Si from various buffer solutions at pH 7 were in the following order: citrate > phosphate > acetate > histidine. In addition, during storage after heating, the Al concentration at certain pHs of phosphate and acetate buffer solution decreased, suggesting the formation of particles containing Al. In citrate buffer, Al did not decrease in spite of the high elution amount. Considering that the solubility profile of aluminum oxide and the Al eluting profile of borosilicate glass were different, it is speculated that Al ion may be forced to leach into the buffer solution according to Si elution on the surface of glass vials. When Al ions were added to the buffer solutions, phosphate, acetate and histidine buffer showed a decrease of Al concentration during storage at a neutral range of pHs, indicating the formation of particles containing Al. In conclusion, it is suggested that phosphate buffer solution has higher possibility of forming particles containing Al than other buffer solutions. PMID:24261406

  13. Activation of a Ca-bentonite as buffer material

    NASA Astrophysics Data System (ADS)

    Huang, Wei-Hsing; Chen, Wen-Chuan

    2016-04-01

    Swelling behavior is an important criterion in achieving the low-permeability sealing function of buffer material. A potential buffer material may be used for radioactive waste repository in Taiwan is a locally available clayey material known as Zhisin clay, which has been identified as a Ca-bentonite. Due to its Ca-based origin, Zhisin was found to exhibit swelling capacity much lower than that of Na-bentonite. To enhance the swelling potential of Zhisin clay, a cation exchange process by addition of Na2CO3 powder was introduced in this paper. The addition of Na2CO3 reagent to Zhisin clay, in a liquid phase, caused the precipitation of CaCO3 and thereby induced a replacement of Ca2+ ions by Na+ ions on the surface of bentonite. Characterization test conducted on Zhisin clay includes chemical analysis, cation exchange capacity, X-ray diffraction, and thermogravimetry (TG). Free-swelling test apparatus was developed according to International Society of Rock Mechanics recommendations. A series of free-swelling tests were conducted on untreated and activated specimens to characterize the effect of activation on the swelling capacity of Zhisin clay. Efforts were made to determine an optimum dosage for the activation, and to evaluate the aging effect. Also, the activated material was evaluated for its stability in various hydrothermal conditions for potential applications as buffer material in a repository. Experimental results show that Na2CO3-activated Zhisin clay is superior in swelling potential to untreated Zhisin clay. Also, there exists an optimum amount of activator in terms of improvements in the swelling capacity. A distinct time-swell relationship was discovered for activated Zhisin clay. The corresponding mechanism refers to exchange of cations and breakdown of quasi-crystal, which results in ion exchange hysteresis of Ca-bentonite. Due to the ion exchange hysteresis, activated bentonite shows a post-rise time-swell relationship different than the sigmoid

  14. The chemical composition and source identification of soil dissolved organic matter in riparian buffer zones from Chongming Island, China.

    PubMed

    Wang, Yulai; Yang, Changming; Li, Jianhua; Shen, Shuo

    2014-09-01

    Dissolved organic matter (DOM) that is derived from the soil of riparian buffer zones has a complex chemical composition, and it plays an important role in the transport and transformation of pollutants. To identify the source of DOM and to better understand its chemical and structural properties, we collected 33 soil samples from zones with fluctuating water levels along the major rivers on Chongming Island, evaluated the DOM contents in riparian soil, analyzed the chemical composition and functional groups and traced DOM origins by using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) combined with clustering analysis. All sampling sites were divided into four groups by principal component analysis (PCA) on the basis of the DOM molecules. The results showed that there was no significant difference in the DOM contents between every two groups; however, the DOM fractions differed significantly among the different site groups in the following order: Σ lipids and Σ proteins>Σ sugars and Σ fatty acids>Σ amino acids, Σ indoles and Σ alkaloids. DOM in the riparian buffer zones originated from riparian plants, domestic sewage and agricultural activities, and the hydrophobic and amphiphilic fractions accounting for over 60% of the identified molecules were the dominant fractions. Our study has confirmed the heterogeneous properties of DOM, and it is of vital importance to isolate and characterize the various DOM fractions at the molecular level for a better understanding of the behavior and roles of DOM in the natural environment. PMID:24997959

  15. Kinetics of bacterial potentiometric titrations: the effect of equilibration time on buffering capacity of Pantoea agglomerans suspensions.

    PubMed

    Kapetas, Leon; Ngwenya, Bryne T; Macdonald, Alan M; Elphick, Stephen C

    2011-07-15

    Several recent studies have made use of continuous acid-base titration data to describe the surface chemistry of bacterial cells as a basis for accurately modelling metal adsorption to bacteria and other biomaterials of potential industrial importance. These studies do not share a common protocol; rather they titrate in different pH ranges and they use different stability criteria to define equilibration time during titration. In the present study we investigate the kinetics of bacterial titrations and test the effect they have on the derivation of functional group concentrations and acidity constants. We titrated suspensions of Pantoea agglomerans by varying the equilibration time between successive titrant additions until stability of 0.1 or 0.001 mV s(-1) was attained. We show that under longer equilibration times, titration results are less reproducible and suspensions exhibit marginally higher buffering. Fluorescence images suggest that cell lysis is not responsible for these effects. Rather, high DOC values and titration reversibility hysterisis after long equilibration times suggest that variability in buffering is due to the presence of bacterial exudates, as demonstrated by titrating supernatants separated from suspensions of different equilibration times. It is recommended that an optimal equilibration time is always determined with variable stability control and preliminary reversibility titration experiments. PMID:21543082

  16. Quantitative Screening of Agrochemical Residues in Fruits and Vegetables by Buffered Ethyl Acetate Extraction and LC-MS/MS Analysis.

    PubMed

    Jadhav, Manjusha R; Oulkar, Dasharath P; Shabeer T P, Ahammed; Banerjee, Kaushik

    2015-05-13

    A buffered ethyl acetate extraction method is proposed for the simultaneous analysis of 296 agrochemicals in a wide range of fruit and vegetable matrices by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimized quantity of acetate buffer (1% acetic acid + 0.5 g of sodium acetate per 10 g of sample) adjusted the pH of each test matrix to 5-6, which in turn significantly improved recoveries of acidic and basic compounds. The role of diethylene glycol (used in the evaporation step) on signal suppression of certain compounds was evaluated, and its quantity was optimized to minimize such an effect. The method was validated in grape, mango, drumstick, bitter gourd, capsicum, curry leaf, and okra as per the DG-SANCO/12571/2013 guidelines. Recoveries in the fortification range of 1-40 μg/kg were within 70-120% with associated relative standard deviations below 20% for most of the compounds. The method has potential for regulatory and commercial applications with a generic approach. PMID:25639652

  17. Running DNA Mini-Gels in 20 Minutes or Less Using Sodium Boric Acid Buffer

    ERIC Educational Resources Information Center

    Jenkins, Kristin P.; Bielec, Barbara

    2006-01-01

    Providing a biotechnology experience for students can be challenging on several levels, and time is a real constraint for many experiments. Many DNA based methods require a gel electrophoresis step, and although some biotechnology procedures have convenient break points, gel electrophoresis does not. In addition to the time required for loading…

  18. Effectiveness of buffered propionic-acid preservatives for large hay packages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most hay producers realize that hays packaged in large-round or large-square bales are particularly sensitive to spontaneous heating, dry matter losses, and negative changes in forage quality. During the last two decades, this has become an important dilemma for hay producers because the cost and av...

  19. A high speed buffer for LV data acquisition

    NASA Technical Reports Server (NTRS)

    Cavone, Angelo A.; Sterlina, Patrick S.; Clemmons, James I., Jr.; Meyers, James F.

    1987-01-01

    The laser velocimeter (autocovariance) buffer interface is a data acquisition subsystem designed specifically for the acquisition of data from a laser velocimeter. The subsystem acquires data from up to six laser velocimeter components in parallel, measures the times between successive data points for each of the components, establishes and maintains a coincident condition between any two or three components, and acquires data from other instrumentation systems simultaneously with the laser velocimeter data points. The subsystem is designed to control the entire data acquisition process based on initial setup parameters obtained from a host computer and to be independent of the computer during the acquisition. On completion of the acquisition cycle, the interface transfers the contents of its memory to the host under direction of the host via a single 16-bit parallel DMA channel.

  20. Job resources buffer the impact of job demands on burnout.

    PubMed

    Bakker, Arnold B; Demerouti, Evangelia; Euwema, Martin C

    2005-04-01

    This study tested and refined the job demands-resources model, demonstrating that several job resources play a role in buffering the impact of several job demands on burnout. A total of 1,012 employees of a large institute for higher education participated in the study. Four demanding aspects of the job (e.g., work overload, emotional demands) and 4 job resources (e.g., autonomy, performance feedback) were used to test the central hypothesis that the interaction between (high) demands and (low) resources produces the highest levels of burnout (exhaustion, cynicism, reduced professional efficacy). The hypothesis was rejected for (reduced) professional efficacy but confirmed for exhaustion and cynicism regarding 18 out of 32 possible 2-way interactions (i.e., combinations of specific job demands and resources). PMID:15826226

  1. Effects of Transitional Buffering Interface coatings on thermal contact conductance

    NASA Astrophysics Data System (ADS)

    Chung, K. C.; Sheffield, J. W.; Sauer, H. J., Jr.; O'Keefe, T. J.; Zhang, J.

    1991-06-01

    Enhancing thermal contact conductance by a reliable and durable coating technique, Transitional Buffering Interface (TBI), has been investigated. A phase mixed coatings, Cu/C, and pure copper coatings on both primary surfaces of specimens were evaluated using four different surface roughnesses. All the samples are being tested at the following contact pressure sequence 125, 250, 375, 500, 375, 250 and 125 kPa. The test results of thermal contact conductance are presented in terms of coating thickness, surface texture and properties of coating materials. Vickers microhardness correlations are also presented for phase mixture copper and carbon and pure copper coatings. Using the experimental data, dimensionless expressions were developed that related the contact conductance of phase mixture copper-carbon and pure copper coatings to the coating thickness, the surface roughness, the contact pressure and the properties of aluminum substrate. The adhesive test indicated good durability of TBI coating surfaces.

  2. A buffer gas cooled beam of barium monohydride

    NASA Astrophysics Data System (ADS)

    Iwata, Geoffrey; Tarallo, Marco; Zelevinsky, Tanya

    2016-05-01

    Significant advances in direct laser cooling of diatomic molecules have opened up a wide array of molecular species to precision studies spanning many-body physics, quantum collisions and ultracold dissociation. We present a cryogenic beam source of barium monohydride (BaH), and study laser ablation of solid precursor targets as well as helium buffer gas cooling dynamics. Additionally, we cover progress towards a molecular magneto-optical trap, with spectroscopic studies of relevant cooling transitions in the B2 Σ <--X2 Σ manifold in laser ablated molecules, including resolution of hyperfine structure and precision measurements of the vibrational Frank-Condon factors. Finally, we examine the feasibility of photo dissociation of trapped BaH molecules to yield optically accessible samples of ultracold hydrogen.

  3. Cobalt disilicide buffer layer for YBCO film on silicon

    SciTech Connect

    Belousov, I.; Rudenko, E.; Linzen, S.; Seidel, P.

    1997-02-01

    The CoSi{sub 2} films were used as buffer layers of YBCO/CoSi{sub 2}/Si(100), YBCO/ZrO{sub 2}/CoSi{sub 2}/Si(100) and YBCO/CeO{sub 2}/YSZ/CoSi{sub 2}/epi-Si/Al{sub 2}O{sub 3} heterostructures in this work. Transition temperatures of YBCO films were obtained up to 86K for YBCO films deposited by laser ablation on the top of CeO{sub 2}/YSZ/CoSi{sub 2}/Si/Al{sub 2}O{sub 3} structure. Local nucleation on the crystal defects of silicon, the phenomenon of lateral directed growth (DLG) and agglomeration of CoSi{sub 2} phase are responsible for grain boundaries (GB) position in CoSi{sub 2} layer and its roughness. The roughness was decreased using an additional Zr film on the top structure.

  4. Estuarine acidification and minimum buffer zone—A conceptual study

    NASA Astrophysics Data System (ADS)

    Hu, Xinping; Cai, Wei-Jun

    2013-10-01

    This study uses a simulation method to explore how estuarine pH is affected by mixing between river water, anthropogenic CO2 enriched seawater, and by respiration. Three rivers with different levels of weathering products (Amazon, Mississippi, and St. Johns) are selected for this simulation. The results indicate that estuaries that receive low to moderate levels of weathering products (Amazon and St. Johns) exhibit a maximum pH decrease in the midsalinity region as a result of anthropogenic CO2 intrusion. This maximum pH decrease coincides with a previously unrecognized mid-salinity minimum buffer zone (MBZ). In addition, water column oxygen consumption can further depress pH for all simulated estuaries. We suggest that recognition of the estuarine MBZs may be important for studying estuarine calcifying organisms and pH-sensitive biogeochemical processes.

  5. A functional description of the Buffered Telemetry Demodulator (BTD)

    NASA Technical Reports Server (NTRS)

    Tsou, H.; Shah, B.; Lee, R.; Hinedi, S.

    1993-01-01

    This article gives a functional description of the buffered telemetry demodulator (BTD), which operates on recorded digital samples to extract the symbols from the received signal. The key advantages of the BTD are as follows: (1) its ability to reprocess the signal to reduce acquisition time; (2) its ability to use future information about the signal and to perform smoothing on past samples; and (3) its minimum transmission bandwidth requirement as each sub carrier harmonic is processed individually. The first application of the BTD would be the Galileo S-band contingency mission, where the signal is so weak that reprocessing to reduce the acquisition time is crucial. Moreover, in the event of employing antenna arraying with full spectrum combining, only the sub carrier harmonics need to be transmitted between sites, resulting in significant reduction in data rate transmission requirements. Software implementation of the BTD is described for various general-purpose computers.

  6. The episodic buffer and learning in early Alzheimer's disease.

    PubMed

    Germano, Carmela; Kinsella, Glynda J; Storey, Elsdon; Ong, Ben; Ames, David

    2008-08-01

    The role of working memory, specifically the episodic buffer, in the learning performance of patients with very mild (n = 18) and mild (n = 12) Alzheimer's disease as compared with healthy older adults (n = 29) was investigated using a series of word-lists that were manipulated (clustered, unclustered) to explore the impact of strategic organizational skills under varying attention conditions (full, divided). Results indicated that the learning performance for all three groups under full attention was better than that under divided attention, but only for the clustered word-lists. Moreover, in contrast to the mild Alzheimer's disease group, both the healthy older controls and the very mild Alzheimer's disease group demonstrated better performance on clustered word-lists than on unclustered lists, suggesting active strategic organizational skills, even at delayed free recall. The overall pattern of results indicates a staging of working-memory impairment in early Alzheimer's disease. PMID:18612873

  7. Superconducting composite with multilayer patterns and multiple buffer layers

    DOEpatents

    Wu, X.D.; Muenchausen, R.E.

    1993-10-12

    An article of manufacture is described including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superconductor. 5 figures.

  8. High-precision buffer circuit for suppression of regenerative oscillation

    NASA Technical Reports Server (NTRS)

    Tripp, John S.; Hare, David A.; Tcheng, Ping

    1995-01-01

    Precision analog signal conditioning electronics have been developed for wind tunnel model attitude inertial sensors. This application requires low-noise, stable, microvolt-level DC performance and a high-precision buffered output. Capacitive loading of the operational amplifier output stages due to the wind tunnel analog signal distribution facilities caused regenerative oscillation and consequent rectification bias errors. Oscillation suppression techniques commonly used in audio applications were inadequate to maintain the performance requirements for the measurement of attitude for wind tunnel models. Feedback control theory is applied to develop a suppression technique based on a known compensation (snubber) circuit, which provides superior oscillation suppression with high output isolation and preserves the low-noise low-offset performance of the signal conditioning electronics. A practical design technique is developed to select the parameters for the compensation circuit to suppress regenerative oscillation occurring when typical shielded cable loads are driven.

  9. How much will evolution buffer changes in climate?

    NASA Astrophysics Data System (ADS)

    Franks, S. J.

    2007-12-01

    Current climate change is altering the phenology, or seasonal timing of reproduction and other life-history events, of many species. There is now evidence that at least some of these changes in phenology represent genetically- based evolution. Evolution may thus potentially serve as a buffer, allowing species to adapt to changes in climatic conditions. However, there are many constraints to evolution, including lack of genetic variation, antagonistic trait correlations, and physiological and developmental constraints. Furthermore, if changes in climate are extremely rapid and severe, many species may experience extinction rather than rapid evolution. I present recent empirical evidence for evolution following changes in climate, examine constraints to evolution, and ask if evolution can keep pace with rapid climate change. The empirical work focuses on the species Brassica rapa, which I show evolved earlier flowering time following several years of drought in Southern California.

  10. A fast data-bus to buffer-memory interface

    NASA Astrophysics Data System (ADS)

    Vander Molen, A.; Maier, M. R.; Robertson, M.; Westfall, G. D.

    1991-09-01

    A fast, economical VME based interface between fast data buses and high speed buffer memories has been built. This module in addition to handling the hand-shaking lines, supplies a gate, a busy signal, and a clear signal at the end of data transfer. A header word with programmable contents is inserted at the beginning of each event giving a discernable event boundary. This device, dubbed the FERA Faucet Maier (FFM), has been applied to the LeCroy ECLine bus coupled to a Creative Electronics Solution 8170 High Speed Memory. It will transfer data at rates up to 10 Mbytes/s from the LeCroy FERAs to the VME based memory.

  11. Formation of buffer-gas-trap based positron beams

    SciTech Connect

    Natisin, M. R. Danielson, J. R. Surko, C. M.

    2015-03-15

    Presented here are experimental measurements, analytic expressions, and simulation results for pulsed, magnetically guided positron beams formed using a Penning-Malmberg style buffer gas trap. In the relevant limit, particle motion can be separated into motion along the magnetic field and gyro-motion in the plane perpendicular to the field. Analytic expressions are developed which describe the evolution of the beam energy distributions, both parallel and perpendicular to the magnetic field, as the beam propagates through regions of varying magnetic field. Simulations of the beam formation process are presented, with the parameters chosen to accurately replicate experimental conditions. The initial conditions and ejection parameters are varied systematically in both experiment and simulation, allowing the relevant processes involved in beam formation to be explored. These studies provide new insights into the underlying physics, including significant adiabatic cooling, due to the time-dependent beam-formation potential. Methods to improve the beam energy and temporal resolution are discussed.

  12. Intelligent deflection routing in buffer-less networks.

    PubMed

    Haeri, Soroush; Trajković, Ljiljana

    2015-02-01

    Deflection routing is employed to ameliorate packet loss caused by contention in buffer-less architectures such as optical burst-switched networks. The main goal of deflection routing is to successfully deflect a packet based only on a limited knowledge that network nodes possess about their environment. In this paper, we present a framework that introduces intelligence to deflection routing (iDef). iDef decouples the design of the signaling infrastructure from the underlying learning algorithm. It consists of a signaling and a decision-making module. Signaling module implements a feedback management protocol while the decision-making module implements a reinforcement learning algorithm. We also propose several learning-based deflection routing protocols, implement them in iDef using the ns-3 network simulator, and compare their performance. PMID:25532199

  13. Determination of baseline human nasal pH and the effect of intranasally administered buffers.

    PubMed

    Washington, N; Steele, R J; Jackson, S J; Bush, D; Mason, J; Gill, D A; Pitt, K; Rawlins, D A

    2000-04-01

    .25 within the first minute. This fell back to a mean pH of 7.07 over the first hour which was still significantly above the baseline. It remained at this value for the remainder of the recording period. The initial average posterior pH was 6.32 and again this did not significantly change over the recording period. Formulation C produced a sustained increase in anterior nasal pH from a baseline pH of 6.57-7.12. A small transient decrease was observed in the pH in the posterior of the nose but baseline pH of 6. 6 was re-established within 15 min post dose. Formulation D significantly reduced anterior nasal pH from 6.30 to 5.87 by 30 min reaching a pH of 5.95 by 90 min where it remained for the remainder of the recording period. The posterior baseline pH was 6.3 and introduction of the pH 5.8 buffer caused a slow increase over 90 min to pH 6.6. Formulation E increased anterior pH from 6.1 to 6.7 for the remainder of the recording period. It had an insignificant effect on posterior nasal pH. The mean (+/-S.D.) time to taste saccharin for formulations A to E was 13.42+/-10.21, 14.67+/-8.37, 11.67+/-8.08, 10.08+/-7.6, 9.80+/-6.73 min, respectively. There was no significant difference between the clearance times for the different formulations. In conclusion, average baseline human nasal pH is approximately 6.3. Nasal anterior pH can be decreased when buffers of 0.13 M and above are used. Mildly acidic solutions produce an increase in pH presumably due to reflux bicarbonate secretion. Posterior nasal pH was not altered by administration of any buffer except the 0.13 M buffer at pH 5.8. This produced a rise in posterior pH. PMID:10767563

  14. Calcium buffer proteins are specific markers of human retinal neurons.

    PubMed

    Kántor, Orsolya; Mezey, Szilvia; Adeghate, Jennifer; Naumann, Angela; Nitschke, Roland; Énzsöly, Anna; Szabó, Arnold; Lukáts, Ákos; Németh, János; Somogyvári, Zoltán; Völgyi, Béla

    2016-07-01

    Ca(2+)-buffer proteins (CaBPs) modulate the temporal and spatial characteristics of transient intracellular Ca(2+)-concentration changes in neurons in order to fine-tune the strength and duration of the output signal. CaBPs have been used as neurochemical markers to identify and trace neurons of several brain loci including the mammalian retina. The CaBP content of retinal neurons, however, varies between species and, thus, the results inferred from animal models cannot be utilised directly by clinical ophthalmologists. Moreover, the shortage of well-preserved human samples greatly impedes human retina studies at the cellular and network level. Our purpose has therefore been to examine the distribution of major CaBPs, including calretinin, calbindin-D28, parvalbumin and the recently discovered secretagogin in exceptionally well-preserved human retinal samples. Based on a combination of immunohistochemistry, Neurolucida tracing and Lucifer yellow injections, we have established a database in which the CaBP marker composition can be defined for morphologically identified cell types of the human retina. Hence, we describe the full CaBP make-up for a number of human retinal neurons, including HII horizontal cells, AII amacrine cells, type-1 tyrosine-hydroxylase-expressing amacrine cells and other lesser known neurons. We have also found a number of unidentified cells whose morphology remains to be characterised. We present several examples of the colocalisation of two or three CaBPs with slightly different subcellular distributions in the same cell strongly suggesting a compartment-specific division of labour of Ca(2+)-buffering by CaBPs. Our work thus provides a neurochemical framework for future ophthalmological studies and renders new information concerning the cellular and subcellular distribution of CaBPs for experimental neuroscience. PMID:26899253

  15. Stability of biodegradable waterborne polyurethane films in buffered saline solutions.

    PubMed

    Lin, Ying Yi; Hung, Kun-Che; Hsu, Shan-Hui

    2015-01-01

    The stability of polyurethane (PU) is of critical importance for applications such as in coating industry or as biomaterials. To eliminate the environmental concerns on the synthesis of PU which involves the use of organic solvents, the aqueous-based or waterborne PU (WBPU) has been developed. WBPU, however, may be unstable in an electrolyte-rich environment. In this study, the authors reported the stability of biodegradable WBPU in the buffered saline solutions evaluated by atomic force microscopy (AFM). Various biodegradable WBPU films were prepared by spin coating on coverslip glass, with a thickness of ∼300 nm. The surface AFM images of poly(ε-caprolactone) (PCL) diol-based WBPU revealed nanoglobular structure. The same feature was observed when 20% molar of the PCL diol soft segment was replaced by polyethylene butylenes adipate diol. After hydration in buffered saline solutions for 24 h, the surface domains generally increased in sizes and became irregular in shape. On the other hand, when the soft segment was replaced by 20% poly(l-lactide) diol, a meshlike surface structure was demonstrated by AFM. When the latter WBPU was hydrated, the surface domains appeared to be disconnected. Results from the attenuated total reflectance infrared spectroscopy and x-ray photoelectron spectroscopy indicated that the surface chemistry of WBPU films was altered after hydration. These changes were probably associated with the neutralization of carboxylate by ions in the saline solutions, resulting in the rearrangements of soft and hard segments and causing instability of the WBPU. PMID:26296357

  16. Cytoplasmic alkalization reduces calcium buffering in molluscan central neurons.

    PubMed

    Zucker, R S

    1981-11-23

    The effect of raised cytoplasmic pH (pHi) on intracellular concentration ([Ca2+]i) transients following calcium influx during membrane depolarization was studied in identified neurons in the abdominal ganglion of Aplysia californica. The pHi was monitored with pH-sensitive microelectrodes. Sea water containing 15 mM NH4Cl at pH 7.7 elevated pHi about 0.35 pH units from the normal level of 7.17. These cells have an estimated buffering power of about 60 mM/pH unit. Calcium influx was elicited by depolarizing pulses under voltage clamp and [Ca2+]i transients were monitored with the photoprotein aequorin or the metallochromic dye arsenazo III. Aequorin photo-emissions increased by 21--131% (mean, 48%) and arsenazo III absorbance changes accompanying depolarization increased by 9--33% (mean, 20%) after 30 min in NH4+, corresponding roughly to a 14% increase in [Ca2+]i transients. Calcium-dependent potassium tail currents following a depolarizing pulse were somewhat slower and 4--91% (mean, 38%) large in NH4+. The magnitude and time- and voltage-dependence of the membrane calcium conductance was studied using calcium tail currents following depolarizing pulses. The calcium current was unaffected by NH4+, so the enhanced [Ca2+]i transients must reflect reduced calcium buffering at high pHi. Either reduced cytoplasmic calcium binding or slowed active extrusion of calcium may be responsible for this effect. PMID:6271335

  17. Oligoglyceric acid synthesis by autocondensation of glyceroyl thioester

    NASA Technical Reports Server (NTRS)

    Weber, A. L.

    1986-01-01

    The autocondensation of the glyceroyl thioester, S-glyceroyl-ethane-thiol, yielded olioglyceric acid. The rates of autocondensation and hydrolysis of the thioester increased from pH 6.5 to pH 7.5 in 2,6-lutidine and imidazole buffers. Autocondensation and hydrolysis were much more rapid in imidazole buffers as compared to 2,6-lutidine and phosphate buffers. The efficiency of ester bond synthesis was about 20% for 40 mM S-glyceroyl-ethane-thiol in 2,6-lutidine and imidazole buffers near neutral pH. The size and yield of the olioglyceric acid products increased when the concentration of the thioester was increased. The relationship of these results to prebiotic polymer synthesis is discussed.

  18. Oligoglyceric acid synthesis by autocondensation of glyceroyl thioester

    NASA Technical Reports Server (NTRS)

    Weber, Arthur L.

    1987-01-01

    The autocondensation of the glyceroyl thioester, S-glyceroyl-ethane-thiol, yielded olioglyceric acid. The rates of autocondensation and hydrolysis of the thioester increased from pH 6.5 to pH 7.5 in 2,6-lutidine and imidazole buffers. Autocondensation and hydrolysis were much more rapid in imidazole buffers as compared to 2,6-lutidine and phosphate buffers. The efficiency of ester bond synthesis was about 20 percent for 40 mM S-glyceroyl-ethane-thiol in 2,6-lutidine and imidazole buffers near neutral pH. The size and yield of the olioglyceric acid products increased when the concentration of the thioester was increased. The relationship of these results to prebiotic polymer synthesis is discussed.

  19. A Simple and Universal Method for Making up Buffer Solutions.

    ERIC Educational Resources Information Center

    Dennison, Clive

    1988-01-01

    Uses a method which involves weighing out an amount of the appropriate weak acid or base and dissolving it in distilled water close to the final volume. Solution is then titrated with strong acid or base to give the desired pH. Provides three examples. (MVL)

  20. Physical-Chemical Treatment of Metals and Radionuclides in the Saturated Zone Using Colloidal Buffers - 12515

    SciTech Connect

    Lai, Yenjung; Borden, Robert C.; Alperin, Ed

    2012-07-01

    There are numerous acidic plumes throughout the DOE complex and the nation as a whole. Low aquifer pH is a major concern since many important radionuclides (Pu, Ra, Sr, Tc) and metals (Cd, Co, Cs, Mn, Ni, Pb, Zn) strongly sorb to iron hydroxides and aluminosilicates under neutral to alkaline conditions, but are mobile in acidic plumes. To effectively use natural and enhanced attenuation (NEA) for management of these contaminants, we must be able to raise aquifer pH and maintain it at background levels until the external acid loading to the aquifer has dissipated. Geochemical modeling showed that a permeable reactive barrier (PRB) formed by injection of colloidal Mg(OH){sub 2} would last much longer than colloidal Ca(OH){sub 2} due to the much lower solubility of Mg(OH){sub 2}. Assuming a 1,000 meq/L suspension of colloidal Mg(OH)2 could be effectively distributed, the PRB could last over twenty years before rejuvenation was required. Preliminary bench-scale treatability studies were conducted to demonstrate the efficacy of increasing the aquifer pH using a colloidal pH buffer. Laboratory studies demonstrated that three different colloidal Mg(OH){sub 2} suspensions (concentration varied from 1,000 to 1,250 meq/L) could be transported through the columns packed with aquifer sand without significant permeability loss. The time before suspension breakthrough into the column effluent varied with surface treatment, indicating the Mg(OH)2 retention and PRB longevity could be controlled by varying the suspension surface treatment. (authors)

  1. Capillary electrophoresis of proteins in buffers containing high concentrations of zwitterionic salts.

    PubMed

    Bushey, M M; Jorgenson, J W

    1989-10-20

    A method for improving protein separations in capillary zone electrophoresis utilizing high concentrations of zwitterionic buffer additives was examined. Lysozyme and alpha-chymotrypsinogen A were used as test proteins in untreated fused-silica capillaries in buffers of pH ca. 7.0 and 9.0 The zwitterion-containing buffers were compared with buffers containing high ionic salt concentrations and a buffer containing a combination of high ionic salt and high zwitterion concentrations. Over 100,000 theoretical plates were obtained in less than 30 min. for both test proteins in a pH 7 buffer containing both trimethylglycine and potassium sulfate. The advantages and disadvantages of this technique compared with those of other methods used to prevent protein adsorption are discussed. PMID:2592485

  2. Dynamically-allocated multi-queue buffers for VLSI communication switches

    NASA Technical Reports Server (NTRS)

    Tamir, Yuval; Frazier, Gregory L.

    1992-01-01

    Several buffer structures are discussed and compared in terms of implementation complexity, interswitch handshaking requirements, and their ability to deal with variations in traffic patterns and message lengths. A new design of buffers is presented that provide non-FIFO message handling and efficient storage allocation for variable size packets using linked lists managed by a simple on-chip controller. The new buffer design is evaluated by comparing it to several alternative designs in the context of a multistage interconnection network. The present modeling and simulations show that the new buffer outperforms alternative buffers and can thus be used to improve the performance of a wide variety of systems currently using less efficient buffers.

  3. Electric field directed nucleic acid hybridization on microchips.

    PubMed Central

    Edman, C F; Raymond, D E; Wu, D J; Tu, E; Sosnowski, R G; Butler, W F; Nerenberg, M; Heller, M J

    1997-01-01

    Selection and adjustment of proper physical parameters enables rapid DNA transport, site selective concentration, and accelerated hybridization reactions to be carried out on active microelectronic arrays. These physical parameters include DC current, voltage, solution conductivity and buffer species. Generally, at any given current and voltage level, the transport or mobility of DNA is inversely proportional to electrolyte or buffer conductivity. However, only a subset of buffer species produce both rapid transport, site specific concentration and accelerated hybridization. These buffers include zwitterionic and low conductivity species such as: d- and l-histidine; 1- and 3-methylhistidines; carnosine; imidazole; pyridine; and collidine. In contrast, buffers such as glycine, beta-alanine and gamma-amino-butyric acid (GABA) produce rapid transport and site selective concentration but do not facilitate hybridization. Our results suggest that the ability of these buffers (histidine, etc.) to facilitate hybridization appears linked to their ability to provide electric field concentration of DNA; to buffer acidic conditions present at the anode; and in this process acquire a net positive charge which then shields or diminishes repulsion between the DNA strands, thus promoting hybridization. PMID:9396795

  4. Sulfuric acid thermoelectrochemical system and method

    DOEpatents

    Ludwig, Frank A.

    1989-01-01

    A thermoelectrochemical system in which an electrical current is generated between a cathode immersed in a concentrated sulfuric acid solution and an anode immersed in an aqueous buffer solution of sodium bisulfate and sodium sulfate. Reactants consumed at the electrodes during the electrochemical reaction are thermochemically regenerated and recycled to the electrodes to provide continuous operation of the system.

  5. Electrophoretic mobilities of cultured human embryonic kidney cells in various buffers

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Data on the electrophoretic mobility distributions of cells in the new D-1 buffer and the interlaboratory standardization of urokinase assay methods are presented. A table of cell strains and recent data on cell dispersal methods are also included. It was decided that glycerol in A-1 electrophoretic mobility data on cultured human embryonic kidney cells subjected to electrophoresis in this buffer. The buffer composition is presented.

  6. Relationships between soil physicochemical, microbiological properties, and nutrient release in buffer soils compared to field soils.

    PubMed

    Stutter, Marc I; Richards, Samia

    2012-01-01

    The retention of nutrients in narrow, vegetated riparian buffer strips (VBS) is uncertain and underlying processes are poorly understood. Evidence suggests that buffer soils are poor at retaining dissolved nutrients, especially phosphorus (P), necessitating management actions if P retention is not to be compromised. We sampled 19 buffer strips and adjacent arable field soils. Differences in nutrient retention between buffer and field soils were determined using a combined assay for release of dissolved P, N, and C forms and particulate P. We then explored these differences in relation to changes in soil bulk density (BD), moisture, organic matter by loss on ignition (OM), and altered microbial diversity using molecular fingerprinting (terminal restriction fragment length polymorphism [TRFLP]). Buffer soils had significantly greater soil OM (89% of sites), moisture content (95%), and water-soluble nutrient concentrations for dissolved organic C (80%), dissolved organic N (80%), dissolved organic P (55%), and soluble reactive P (70%). Buffer soils had consistently smaller bulk densities than field soils. Soil fine particle release was generally greater for field than buffer soils. Significantly smaller soil bulk density in buffer soils than in adjacent fields indicated increased porosity and infiltration in buffers. Bacterial, archaeal, and fungal communities showed altered diversity between the buffer and field soils, with significant relationships with soil BD, moisture, OM, and increased solubility of buffer nutrients. Current soil conditions in VBS appear to be leading to potentially enhanced nutrient leaching via increasing solubility of C, N, and P. Manipulating soil microbial conditions (by management of soil moisture, vegetation type, and cover) may provide options for increasing the buffer storage for key nutrients such as P without increasing leaching to adjacent streams. PMID:22370402

  7. Using GIS to Quantify Riparian Buffer Bypassing on Agricultural Fields in the Chesapeake Bay Watershed

    NASA Astrophysics Data System (ADS)

    Funkhouser, L.; Hancock, G. S.; Kaste, J. M.

    2011-12-01

    Forested riparian buffers are intended to reduce the sediment and nutrient loads to streams delivered by agricultural runoff. Within the Chesapeake Bay Watershed, buffers are mandated to be 100' wide along agricultural fields bordered by perennial streams. When flow into buffers is widely disseminated buffers have the potential to significantly reduce pollutant levels entering streams. However, several studies show that flow across buffers is often concentrated, producing channelized flow that bypasses the buffer and presumably reduces buffer effectiveness. Previous studies have relied on field observations in relatively few locations, however, and the extent of bypassing is not well constrained. We hypothesize that buffer bypassing and the associated reduction in buffer effectiveness is a widespread phenomenon. Here we use GIS to determine flow patterns on agricultural fields and to identify locations of concentrated flow through buffers in the Virginia Coastal Plain within the Chesapeake Bay Watershed. Using DEMs with ≤10m resolution, we determine flow accumulation along field margins and identify points with flow accumulation sufficient to generate concentrated flow into buffers. Preliminary data from ~20 fields has been obtained by creating a field outline attached to flow accumulation points generated in ArcMap. We find that 66% to 91% of the total area draining to the field margins pass through discrete points representing <5% of the field margin length. On-field observations show evidence for surface flow and channelization at approximately 90% of the discrete drainage points identified in our hydrologic analysis using GIS. Our preliminary observations suggest buffer bypassing is widespread in this region of relatively low relief. We will present GIS and field analysis from a total of ~50 fields and attempt to identify the area/slope relationship necessary to generate channelization and bypassing at field margins.

  8. Doped Y.sub.2O.sub.3 buffer layers for laminated conductors

    DOEpatents

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2007-08-21

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the metallic substrate, the biaxially textured buffer layer comprising Y.sub.2O.sub.3 and a dopant for blocking cation diffusion through the Y.sub.2O.sub.3, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  9. Effect of carotenoids and monogalactosyl diglyceride on bacteriochlorophyll c aggregates in aqueous buffer: implications for the self-assembly of chlorosomes.

    PubMed

    Klinger, Pavel; Arellano, Juan B; Vácha, Frantisek; Hála, Jan; Psencík, Jakub

    2004-01-01

    Aggregation of bacteriochlorophyll (BChl) c from chlorosomes, the main light-harvesting complex of green bacteria, has been studied in aqueous buffer. Unlike other chlorophyll-like molecules, BChl c is rather soluble in aqueous buffer, forming dimers. When BChl c is mixed with carotenoids (Car), the BChl c Qy transition is further redshifted, in respect to that of monomers and dimers. The results suggest that Car are incorporated in the aggregates and induce further aggregation of BChl c. The redshift of the BChl c Qy band is proportional to the Car concentration. In contrast, the mixture of bacteriochlorophyllide (BChlide) c, which lacks the nonpolar esterifying alcohol, does not form aggregates with Car in aqueous buffer or nonpolar solvents. Instead, the position of the BChlide c Qy transition remains unshifted in respect to that of the monomeric molecule, and Car precipitates with the course of time in aqueous buffer. Similar effects on both BChl c and BChlide c are also observed when monogalactosyl diglyceride (MGDG), which forms the monolayer envelope of chlorosomes, is used instead of (or together with) Car. The results show that the hydrophobic interactions of the BChl c esterifying alcohols with themselves and the nonpolar carbon skeleton of Car, or the fatty acid tails of MGDG, are essential driving forces for BChl aggregation in chlorosomes. PMID:15623345

  10. Atmospheric dust and acid rain

    SciTech Connect

    Hedin, L.O.; Likens, G.E.

    1996-12-01

    Why is acid rain still an environmental problem in Europe and North America despite antipollution reforms? The answer really is blowing in the wind: atmospheric dust. These airborne particles can help neutralize the acids falling on forests, but dust levels are unusually low these days. In the air dust particles can neutralize acid rain. What can we do about acid rain and atmospheric dust? Suggestions range from the improbable to the feasible. One reasonable suggestion is to reduce emissions of acidic pollutants to levels that can be buffered by natural quantities of basic compounds in the atmosphere; such a goal would mean continued reductions in sulfur dioxide and nitrogen oxides, perhaps even greater than those prescribed in the 1990 Amendments to the Clean Air Act in the U.S. 5 figs.

  11. Autophagy on acid.

    PubMed

    Wojtkowiak, Jonathan W; Gillies, Robert J

    2012-11-01

    The microenvironment of solid tumors tends to be more acidic (6.5-7.0) than surrounding normal (7.2-7.4) tissue. Chaotic vasculature, oxygen limitation and major metabolic changes all contribute to the acidic microenvironment. We have previously proposed that low extracellular pH (pHe) plays a critical role in the development and progression of solid tumors. While extracellular acidosis is toxic to most normal cells, cancer cells can adapt and survive under this harsh condition. In this study, we focused on identifying survival strategies employed by cancer cells when challenged with an acidic pHe (6.6-6.7) either acutely or for many generations. While acutely acidic cells did not grow, those acclimated over many generations grew at the same rate as control cells. We observed that these cells induce autophagy in response to acidosis both acutely and chronically, and that this adaptation appears to be necessary for survival. Inhibition of autophagy in low pH cultured cells results in cell death. Histological analysis of tumor xenografts reveals a strong correlation of LC3 protein expression in regions projected to be acidic. Furthermore, in vivo buffering experiments using sodium bicarbonate, previously shown to raise extracellular tumor pH, decreases LC3 protein expression in tumor xenografts. These data imply that autophagy can be induced by extracellular acidosis and appears to be chronically employed as a survival adaptation to acidic microenvironments. PMID:22874557

  12. Data on four criteria for targeting the placement of conservation buffers in agricultural landscapes.

    PubMed

    Qiu, Zeyuan; Dosskey, Michael G; Kang, Yang

    2016-06-01

    Four criteria are generally used to prioritize agricultural lands for placing conservation buffers. The criteria include soil erodibility, hydrological sensitivity, wildlife habitat, and impervious surface rate that capture conservation buffers' benefits in reducing soil erosion, controlling runoff generation, enhancing wildlife habitat, and mitigating stormwater impacts, respectively. This article describes the data used to derive the values of those attributes and a scheme to classify the values in multi-criteria analysis of conservation buffer placement in "Choosing between alternative placement strategies for conservation buffers using borda count" [1]. PMID:27222843

  13. Effect of buffer gases on the performance of SO2 trace measurement based on photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Mohebbifar, M. R.; Khalilzadeh, J.; Dibaee, B.; Parvin, P.

    2014-07-01

    In this experimental work a laser photoacoustic spectrometer designed and fabricated. System sensitivity for detection of SO2 and NO2 was measured. Resonance frequency variation versus pressure increase of Nitrogen, Argon, Helium and Air buffer gases was studied. Results show that, sensitivity of system for SO2 and NO2 are 353 ppb and 963 ppb respectively. It was shown that resonance frequency for Nitrogen, Argon, and Air buffer gases was not noticeably varied by buffer gas pressure increasing, but for Helium, resonance frequency not only is not in range of three other gases, but also grows by pressure increasing. The system noises were damped preparing two buffer chambers.

  14. Effects of hypertonic buffer composition on lymph node uptake and bioavailability of rituximab, after subcutaneous administration

    PubMed Central

    Fathallah, Anas M.; Turner, Michael R.; Balu-Iyer, Sathy V.

    2015-01-01

    Subcutaneous administration of biologics is highly desirable; however, incomplete bioavailability after sc administration remains a major challenge. In this work we investigated the effects of excipient dependent hyper-osmolarity on lymphatic uptake and plasma exposure of rituximab as a model protein. Using Swiss Webster (SW) mice as our animal model, we compared the effects of NaCl, mannitol and, O-Phospho-L-Serine (OPLS) on plasma concentration of rituximab over 5 days after sc administration. We observed an increase in plasma concentrations in animals administered rituximab in hypertonic buffer solutions, as compared to isotonic buffer. Bioavailability, as estimated by our pharmacokinetic model, increased from 29% in isotonic buffer to 54% in hypertonic buffer containing NaCl, to almost complete bioavailability in hypertonic buffers containing high dose OPLS or mannitol. This improvement in plasma exposure is due to improved lymphatic trafficking as evident from the increase in the fraction of dose trafficked through the lymph node in the presence of hypertonic buffers. The fraction of the dose trafficked through the lymphatic, as estimated by the model, increased from 0.05 % in isotonic buffer to 13% in hyper-tonic buffer containing NaCl to about 30% for hypertonic buffers containing high dose OPLS and mannitol. Our data suggests that hypertonic solutions may be a viable option to improve sc bioavailability. PMID:25377184

  15. Demographic buffering of life histories? Implications of the choice of measurement scale.

    PubMed

    Bjørkvoll, Eirin; Lee, Aline M; Grøtan, Vidar; Saether, Bernt-Erikik; Stien, Audun; Engen, Steinar; Albon, Steve; Loe, Leif Egil; Hansen, Brage Bremset

    2016-01-01

    Life-history theory predicts that the vital rates that influence population growth the most should be buffered against environmental fluctuations due to selection for reduced variation. However, it remains unclear whether populations actually are influenced by such "demographic buffering," because variation in vital rates can be compared on different measurement scales, and there has been little attempt to investigate whether the choice of scale influences the chance of detecting demographic buffering. We compared two statistical approaches to examine whether demographic buffering has influenced vital rates in wild Svalbard reindeer (Rangifer tarandus platyrhynchus). To account for statistical variance constraints on vital rates limited between 0 and 1 in analyses of demographic buffering, one approach is to scale observed variation by the maximum possible variation on the arithmetic scale. When applying this approach, the results suggested that demographic buffering was occurring. However, when we applied an alternative approach that identified statistical variance constraints on the logit scale, there was no evidence for demographic buffering. Thus, the choice of measurement scale must be carefully considered before one can fully understand whether demographic buffering influences life histories. Defining the appropriate scale may require an understanding of the mechanisms through which demographic buffering may have evolved. PMID:27008773

  16. Mechanisms and Functional Implications of Social Buffering in Infants: Lessons from Animal Models

    PubMed Central

    Sullivan, Regina M.; Perry, Rosemarie E.

    2015-01-01

    Social buffering, which is the attenuation of stress hormone release by a social partner, occurs in many species throughout the lifespan. Social buffering of the infant by the caregiver is particularly robust, and animal models using infant rodents are uncovering the mechanisms and neural circuitry supporting social buffering. At birth, the hypothalamic-pituitary-adrenal (HPA) stress system is functional but is suppressed via extended social buffering by the mother: the profound social buffering effects of the mother can last for one to two hours when pups are removed from the mother. At 10 days of age, pups begin to mount a stress response immediately when separated from the mother. The stimuli from the mother supporting social buffering are broad, for tactile stimulation, milk, and an anesthetized mother (no maternal behavior) all sufficiently support social buffering. The mother appears to produce social buffering by blocking norepinephrine (NE) release into the hypothalamic paraventricular nucleus (PVN), which blocks HPA activation. Since the infant amygdala relies on the presence of corticosterone (CORT), this suggests that social buffering of pups by the mother attenuates the neurobehavioral stress response in infancy and prevents pups from learning about threat within mother-infant interactions. PMID:26324338

  17. Setting priorities for research on pollution reduction functions of agricultural buffers.

    PubMed

    Dosskey, Michael G

    2002-11-01

    The success of buffer installation initiatives and programs to reduce nonpoint source pollution of streams on agricultural lands will depend the ability of local planners to locate and design buffers for specific circumstances with substantial and predictable results. Current predictive capabilities are inadequate, and major sources of uncertainty remain. An assessment of these uncertainties cautions that there is greater risk of overestimating buffer impact than underestimating it. Priorities for future research are proposed that will lead more quickly to major advances in predictive capabilities. Highest priority is given for work on the surface runoff filtration function, which is almost universally important to the amount of pollution reduction expected from buffer installation and for which there remain major sources of uncertainty for predicting level of impact. Foremost uncertainties surround the extent and consequences of runoff flow concentration and pollutant accumulation. Other buffer functions, including filtration of groundwater nitrate and stabilization of channel erosion sources of sediments, may be important in some regions. However, uncertainty surrounds our ability to identify and quantify the extent of site conditions where buffer installation can substantially reduce stream pollution in these ways. Deficiencies in predictive models reflect gaps in experimental information as well as technology to account for spatial heterogeneity of pollutant sources, pathways, and buffer capabilities across watersheds. Since completion of a comprehensive watershed-scale buffer model is probably far off, immediate needs call for simpler techniques to gage the probable impacts of buffer installation at local scales. PMID:12375085

  18. Effect of buffer structures on AlGaN/GaN high electron mobility transistor reliability

    SciTech Connect

    Liu, L.; Xi, Y. Y.; Ren, F.; Pearton, S. J.; Laboutin, O.; Cao, Yu; Johnson, Wayne J.; Kravchenko, Ivan I

    2012-01-01

    AlGaN/GaN high electron mobility transistors (HEMTs) with three different types of buffer layers, including a GaN/AlGaN composite layer, or 1 or 2 lm GaN thick layers, were fabricated and their reliability compared. The HEMTs with the thick GaN buffer layer showed the lowest critical voltage (Vcri) during off-state drain step-stress, but this was increased by around 50% and 100% for devices with the composite AlGaN/GaN buffer layers or thinner GaN buffers, respectively. The Voff - state for HEMTs with thin GaN and composite buffers were 100 V, however, this degraded to 50 60V for devices with thick GaN buffers due to the difference in peak electric field near the gate edge. A similar trend was observed in the isolation breakdown voltage measurements, with the highest Viso achieved based on thin GaN or composite buffer designs (600 700 V), while a much smaller Viso of 200V was measured on HEMTs with the thick GaN buffer layers. These results demonstrate the strong influence of buffer structure and defect density on AlGaN/GaN HEMT performance and reliability.

  19. Germination and inactivation of Bacillus coagulans and Alicyclobacillus acidoterrestris spores by high hydrostatic pressure treatment in buffer and tomato sauce.

    PubMed

    Vercammen, Anne; Vivijs, Bram; Lurquin, Ine; Michiels, Chris W

    2012-01-16

    Acidothermophilic bacteria like Alicyclobacillus acidoterrestris and Bacillus coagulans can cause spoilage of heat-processed acidic foods because they form spores with very high heat resistance and can grow at low pH. The objective of this work was to study the germination and inactivation of A. acidoterrestris and B. coagulans spores by high hydrostatic pressure (HP) treatment at temperatures up to 60°C and both at low and neutral pH. In a first experiment, spores suspended in buffers at pH 4.0, 5.0 and 7.0 were processed for 10min at different pressures (100-800MPa) at 40°C. None of these treatments caused any significant inactivation, except perhaps at 800MPa in pH 4.0 buffer where close to 1 log inactivation of B. coagulans was observed. Spore germination up to about 2 log was observed for both bacteria but occurred mainly in a low pressure window (100-300MPa) for A. acidoterrestris and only in a high pressure window (600-800MPa) for B. coagulans. In addition, low pH suppressed germination in A. acidoterrestris, but stimulated it in B. coagulans. In a second series of experiments, spores were treated in tomato sauce of pH 4.2 and 5.0 at 100 - 800MPa at 25, 40 and 60°C for 10min. At 40°C, results for B. coagulans were similar as in buffer. For A. acidoterrestris, germination levels in tomato sauce were generally higher than in buffer, and showed little difference at low and high pressure. Remarkably, the pH dependence of A. acidoterrestris spore germination was reversed in tomato sauce, with more germination at the lowest pH. Furthermore, HP treatments in the pH 4.2 sauce caused between 1 and 1.5 log inactivation of A. acidoterrestris. Germination of spores in the high pressure window was strongly temperature dependent, whereas germination of A. acidoterrestris in the low pressure window showed little temperature dependence. When HP treatment was conducted at 60°C, most of the germinated spores were also inactivated. For the pH 4.2 tomato sauce, this

  20. Simultaneous Determination of Potassium Sorbate, Sodium Benzoate, Quinoline Yellow and Sunset Yellow in Lemonades and Lemon Sauces by HPLC Using Experimental Design.

    PubMed

    Dinç Zor, Şule; Aşçı, Bürge; Aksu Dönmez, Özlem; Yıldırım Küçükkaraca, Dilek

    2016-07-01

    In this study, development and validation of a HPLC method was described for simultaneous determination of potassium sorbate, sodium benzoate, quinoline yellow and sunset yellow. A Box-Behnken design using three variables at three levels was employed to determine the optimum conditions of chromatographic separation: pH of mobile phase, 6.0-7.0; flow rate, 0.8-1.2 mL min(-1) and the ratio of mobile phase composed of a 0.025 M sodium acetate/acetic acid buffer, 80-90%. Resolution was chosen as a response. The optimized method was validated for linearity, the limits of detection and quantification, accuracy, precision and stability. All the validation parameters were within the acceptance range. The applicability of the developed method to the determination of these food additives in commercial lemonade and lemon sauce samples was successfully demonstrated. PMID:26951541

  1. Development of buffer layers by chemical solution deposition for YBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Akin, Yalcin

    Short length YBCO coated conductors have been fabricated by vacuum thin film deposition techniques. However, the fabrication process increases the cost, and makes them impractical to use for commercial applications even if they are fabricated in kilometer lengths. YBCO coated conductors could be available in the market with a cheaper price by developing non-vacuum deposition techniques. The objective of this research was to investigate development of buffer layers by chemical solution deposition technique for YBCO coated conductors. Buffer layer structures are mainly used to prevent metal ion diffusion, and to reduce the lattice mismatch between YBCO and the metallic substrate. The technical approach, which was adapted here, is the reel-to-reel sol-gel dip coating process to fabricate long length coatings by developing buffer layers' chemical solutions. Rolling assisted biaxially textured Ni substrates were used for deposition of buffer layers. Cold rolled Ni strips were heat-treated at certain conditions to form biaxially textured structure, which became templates for textured growth of buffer layers that is necessary to obtain high critical current in the coated conductors. CeO2 was chosen as a buffer layers because it has been recognized as one of the best cap layers. Growth of highly textured, crack free, pinhole free and smooth CeO2 buffer layers have been demonstrated by chemical solution deposition technique on biaxially textured substrates. A new buffer layer with pseudocubic lattice parameters matching YBCO, (Eu0.893Yb0.107)2O3, was developed for the first time by using a mixture of Eu2O 3 and Yb2O3 to eliminate lattice mismatch, which adversely affected the critical current of the coated conductors. Highly textured (Eu0.893Yb0.107)2O3 buffer layers were deposited on biaxially textured Ni substrates by chemical solution deposition technique. Finally, the growth of CeO2 and (Eu0.893Yb 0.107)2O3 buffer layers were investigated on oxide layers because both Ce

  2. Effect of Oxide Buffer Layer on the Thermochromic Properties of VO2 Thin Films

    NASA Astrophysics Data System (ADS)

    Koo, Hyun; Xu, Lu; Ko, Kyeong-Eun; Ahn, Seunghyun; Chang, Se-Hong; Park, Chan

    2013-12-01

    VO2 thin films were deposited on soda lime glass substrates with ZnO, TiO2, SnO2, and CeO2 thin films applied as buffer layers between the VO2 films and the substrates in order to investigate the effect of buffer layer on the formation and the thermochromic properties of VO2 film. Buffer layers with thicknesses over 50 nm were found to affect the formation of VO2 film, which was confirmed by XRD spectra. By using ZnO, TiO2, and SnO2 buffer layers, monoclinic VO2 (VO2(M)) film was successfully fabricated on soda lime glass at 370 °C. On the contrary, films of VO2(B), which is known to have no phase transition near room temperature, were formed rather than VO2(M) when the film was deposited on CeO2 buffer layer at the same film deposition temperature. The excellent thermochromic properties of the films deposited on ZnO, TiO2, and SnO2 buffer layers were confirmed from the temperature dependence of electrical resistivity from room temperature to 80 °C. Especially, due to the tendency of ZnO thin film to grow with a high degree of preferred orientation on soda lime glass at low temperature, the VO2 film deposited on ZnO buffer layer exhibits the best thermochromic properties compared to those on other buffer layer materials used in this study. These results suggest that deposition of VO2 films on soda lime glass at low temperature with excellent thermochromic properties can be achieved by considering the buffer layer material having structural similarity with VO2. Moreover, the degree of crystallization of buffer layer is also related with that of VO2 film, and thus ZnO can be one of the most effective buffer layer materials.

  3. Effect of buffer media composition on the solubility and effective permeability coefficient of ibuprofen.

    PubMed

    Levis, Karl A; Lane, Majella E; Corrigan, Owen I

    2003-03-01

    The effect of perfusion medium composition on the two important biopharmaceutical parameters drug solubility and permeability was determined for ibuprofen. Eight commonly used buffers were examined. Equilibrium solubility, buffer capacity profiles and permeability coefficients, using the in situ rat gut perfusion model, were determined for each medium at 37 degrees C. The solubility of ibuprofen differed sixfold over the range of buffer systems studied. The differences in solubility were associated with different pHs of the buffers when saturated with drug and also the presence of micelles and divalent ions. The solubility of ibuprofen in FeSSIF was significantly higher than predicted from the pH due to micellisation, while that in Krebs was significantly lower due to ibuprofen-calcium salt formation. Buffer capacities varied over a 40-fold range. The pK(a) values of the buffer components were determined from the buffer capacity versus pH profiles and were in good agreement with the thermodynamic values when corrected for temperature and ionic strength. Smaller, but statistically significant differences in P(app) values for ibuprofen were also observed between some of the buffers. During perfusion, pHs of the perfusate samples gradually changed over time towards a median value of approximately 6.5. HBSS gave a P(app) approximately 50% greater than that observed in PBS 7.4. Physicochemical factors such as medium pH, buffer capacity and osmolarity should be considered when determining the P(app) values of ionisable compounds. Care needs to be exercised when comparing P(app) values from different laboratories as buffer composition can have a significant effect on both solubility and permeability of a drug, whose ionisation is substantially changed over the pH range of the buffers. Despite the high amount ionised, ibuprofen appears to be well absorbed and it can be classified as a highly permeable drug. PMID:12593936

  4. Effects of Riparian Buffer Vegetation and Width: A 12-Year Longitudinal Study.

    PubMed

    King, S E; Osmond, D L; Smith, J; Burchell, M R; Dukes, M; Evans, R O; Knies, S; Kunickis, S

    2016-07-01

    Agricultural contributions of nitrogen are a serious concern for many water resources and have spurred the implementation of riparian buffer zones to reduce groundwater nitrate (NO). The optimum design for buffers is subject to debate, and there are few long-term studies. The objective of this project was to determine the effectiveness over time (12 yr) of buffer types (trees, switchgrass, fescue, native, and a control) and buffer widths (8 and 15 m) by measuring groundwater NO-N and dissolved organic carbon (DOC) trends. At the intermediate groundwater depth (1.5-2.1 m), NO-N reduction effectiveness was 2.5 times greater (46 vs. 16%) for the wider buffer, and, regardless of width, buffer effectiveness increased 0.62% yr. Buffer vegetative type was never statistically significant. In the deep-groundwater depth (2.1-3.5 m), there was no change in NO-N removal over time, although the statistical interaction of width and vegetative type indicated a wide range of removal rates (19-82%). The DOC concentrations were analyzed at the field/buffer and buffer/stream sampling locations. Depending on location position and groundwater sampling depth, DOC concentrations ranged from 1.6 to 2.8 mg L at Year 0 and increased at a rate of 0.13 to 0.18 mg L yr but always remained low (≤5.0 mg L). Greater DOC concentrations in the intermediate-depth groundwater did not increase NO-N removal; redox measurements indicated intermittent reduced soil conditions may have been limiting. This study suggests that riparian buffer width, not vegetation, is more important for NO-N removal in the middle coastal plain of North Carolina for a newly established buffer. PMID:27380072

  5. Field-based evaluation tool for riparian buffer zones in agricultural catchments.

    PubMed

    Ducros, Caroline M J; Joyce, Chris B

    2003-08-01

    Riparian buffer zones can improve water quality and enhance habitat, but a comprehensive yet rapid method that can assist the resource manager in assessing the effectiveness of buffers is not available. The aim of this paper is to describe and illustrate the use of a newly developed field-based evaluation tool for riparian buffer zones in agricultural catchments. The Buffer Zone Inventory and Evaluation Form (BZIEF) incorporates criteria-based scoring systems developed from literature review, subsequent peer-review, and then a pilot field study. Use of the BZIEF is demonstrated by comparing buffer zones in three catchments established for water quality and habitat improvement under the Water Fringe Option agrienvironment scheme in England in order to assess whether the buffers were likely to provide environmental enhancement. Results among the three catchments were generally similar; buffer zones scored highly for their abundant vegetation cover, lack of erosion, stream habitat quality, and sufficient width. Furthermore, previous grassland or arable land use did not substantially affect buffer zone ratings. However, the BZIEF indicated that inappropriate soil characteristics in one catchment were likely to constrain buffer zone effectiveness for improving water quality. In another catchment, poor riparian vegetation diversity and structure may yield ineffective habitat enhancement, according to the BZIEF. It was concluded that the BZIEF might be a useful tool for buffer zone comparison and monitoring, even though more work is needed to test and validate the method. For example, the BZIEF could be used to target appropriate locations for buffer zones and is flexible, so could be adapted for different policies, objectives and regions. PMID:14753650

  6. Development and Evaluation of a Riparian Buffer Mapping Tool

    USGS Publications Warehouse

    Milheim, Lesley E.; Claggett, Peter R.

    2008-01-01

    Land use and land cover within riparian areas greatly affect the conditions of adjacent water features. In particular, riparian forests provide many environmental benefits, including nutrient uptake, bank stabilization, steam shading, sediment trapping, aquatic and terrestrial habitat, and stream organic matter. In contrast, residential and commercial development and associated transportation infrastructure increase pollutant and nutrient loading and change the hydrologic characteristics of the landscape, thereby affecting both water quality and habitat. Restoring riparian areas is a popular and cost effective restoration technique to improve and protect water quality. Recognizing this, the Chesapeake Executive Council committed to restoring 10,000 miles of riparian forest buffers throughout the Chesapeake Bay watershed by the year 2010. In 2006, the Chesapeake Executive Council further committed to 'using the best available...tools to identify areas where retention and expansion of forests is most needed to protect water quality'. The Chesapeake Bay watershed encompasses 64,000 square miles, including portions of six States and Washington, D.C. Therefore, the interpretation of remotely sensed imagery provides the only effective technique for comprehensively evaluating riparian forest protection and restoration opportunities throughout the watershed. Although 30-meter-resolution land use and land cover data have proved useful on a regional scale, they have not been equally successful at providing the detail required for local-scale assessment of riparian area characteristics. Use of high-resolution imagery (HRI) provides sufficient detail for local-scale assessments, although at greater cost owing to the cost of the imagery and the skill and time required to process the data. To facilitate the use of HRI for monitoring the extent of riparian forest buffers, the U.S. Forest Service and the U.S. Geological Survey Eastern Geographic Science Center funded the

  7. Functional PEG–PAMAM-Tetraphosphonate Capped NaLnF4 Nanoparticles and their Colloidal Stability in Phosphate Buffer

    PubMed Central

    2015-01-01

    Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (Mn = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (Mn = 2000) and biotin-terminated PEG (Mn = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000–PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir2012, 28, 12861−1287022906305) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline. PMID:24898128

  8. Iron clad wetlands: Soil iron-sulfur buffering determines coastal wetland response to salt water incursion

    NASA Astrophysics Data System (ADS)

    Schoepfer, Valerie A.; Bernhardt, Emily S.; Burgin, Amy J.

    2014-12-01

    Coastal freshwater wetland chemistry is rapidly changing due to increased frequency of salt water incursion, a consequence of global change. Seasonal salt water incursion introduces sulfate, which microbially reduces to sulfide. Sulfide binds with reduced iron, producing iron sulfide (FeS), recognizable in wetland soils by its characteristic black color. The objective of this study is to document iron and sulfate reduction rates, as well as product formation (acid volatile sulfide (AVS) and chromium reducible sulfide (CRS)) in a coastal freshwater wetland undergoing seasonal salt water incursion. Understanding iron and sulfur cycling, as well as their reduction products, allows us to calculate the degree of sulfidization (DOS), from which we can estimate how long soil iron will buffer against chemical effects of sea level rise. We show that soil chloride, a direct indicator of the degree of incursion, best predicted iron and sulfate reduction rates. Correlations between soil chloride and iron or sulfur reduction rates were strongest in the surface layer (0-3 cm), indicative of surface water incursion, rather than groundwater intrusion at our site. The interaction between soil moisture and extractable chloride was significantly related to increased AVS, whereas increased soil chloride was a stronger predictor of CRS. The current DOS in this coastal plains wetland is very low, resulting from high soil iron content and relatively small degree of salt water incursion. However, with time and continuous salt water exposure, iron will bind with incoming sulfur, creating FeS complexes, and DOS will increase.

  9. Synthesis and characterization of a novel chitosan-N-acetyl-homocysteine thiolactone polymer using MES buffer.

    PubMed

    Ferris, C; Casas, M; Lucero, M J; de Paz, M V; Jiménez-Castellanos, M R

    2014-10-13

    We report a new "green" approach to synthesize a novel thiolated chitosan conjugate, chitosan-N-acetyl-homocysteine thiolactone (chitosan-AcHcys) using a "Good's buffers", 2-(N-morpholino)ethanesulfonic acid (MES). After that, the crosslinked Xr-chitosan-AcHcys was obtained only in the presence of air, without other reactants. The chitosan-AcHcys spectrum shows a partial incorporation of the thiolactone onto the polymer backbone. The derivative thermogravimetric analysis confirmed that chitosan-AcHcys is slightly less stable than starting chitosan; however, the peak profile is broadened which is indicative of deeper changes in the thermal degradation process. Also, aqueous dispersions with different concentrations of the crosslinked material (Xr-chitosan-AcHcys) were prepared and rheologically characterized. All aqueous dispersions are viscoelastic fluid with shear-thinning behavior. The viscosity of the dispersions (1-7% of chitosan-AcHcys) increases as a function of polymer concentration. So, we have achieved to disperse a high concentration of thiolated-chitosan derivative in water with different rheological characteristics, which could affect the drug release. PMID:25037337

  10. Modeling the hepatic arterial buffer response in the liver.

    PubMed

    Ho, Harvey; Sorrell, Keagan; Bartlett, Adam; Hunter, Peter

    2013-08-01

    In this paper we present an electrical analog model for the hepatic arterial buffer response (HABR), an intrinsic regulation mechanism in the liver whereby the arterial flow counteracts the changes in portal venous flow. The model itself is a substantial simplification of a previously published model, with nonlinear arterial and portal resistors introduced to account for the dynamic HABR effects. We calibrate the baseline model using published hemodynamic data, and then perform a virtual portal occlusion simulation where the portal vein is half or fully occluded. The simulation results, which suggest that the increased arterial flow cannot fully compensate lost portal perfusion, are consistent with clinical reports and animal model findings. Since HABR functions in both the whole liver and liver graft after transplantation, we also simulate blood flow in a virtual right-lobe graft by adjusting the electronic component parameters in the electric circuit, and our model is able to reproduce the portal venous hyperperfusion and hepatic arterial hypoperfusion conditions due to the HABR effects. PMID:23157977

  11. Perceived personal control buffers terminal decline in well-being.

    PubMed

    Gerstorf, Denis; Heckhausen, Jutta; Ram, Nilam; Infurna, Frank J; Schupp, Jürgen; Wagner, Gert G

    2014-09-01

    Recent research has repeatedly demonstrated that well-being typically evinces precipitous deterioration close to the end of life. However, the determinants of individual differences in these terminal declines are not well understood. In this study, we examine the role of perceived personal control as a potential buffer against steep terminal declines in well-being. We applied single- and multiphase growth models to up to 25-year longitudinal data from 1,641 now-deceased participants of the national German Socio-Economic Panel Study (SOEP; age at death: M = 74 years; SD = 14; 49% women). Results revealed that perceiving more personal control over one's life was related to subsequently higher late-life well-being, less severe rates of late-life declines, and a later onset of terminal decline. Associations were independent of key predictors of mortality, including age, gender, SES, and disability. These findings suggest that feeling in control may ameliorate steep end-of-life decline in well-being. We also discuss scenarios for when and how processes of goal disengagement and giving up control may become beneficial. PMID:25244480

  12. Are temperate mature forests buffered from invasive lianas?

    USGS Publications Warehouse

    Pavlovic, Noel B.; Leicht-Young, Stacey A.

    2011-01-01

    Mature and old-growth forests are often thought to be buffered against invasive species due to low levels of light and infrequent disturbance. Lianas (woody vines) and other climbing plants are also known to exhibit lower densities in older forests. As part of a larger survey of the lianas of the southern Lake Michigan region in mature and old-growth forests, the level of infestation by invasive lianas was evaluated. The only invasive liana detected in these surveys was Celastrus orbiculatus Thunb. (Celastraceae). Although this species had only attached to trees and reached the canopy in a few instances, it was present in 30% of transects surveyed, mostly as a component of the ground layer. Transects with C. orbiculatus had higher levels of soil potassium and higher liana richness than transects without. In contrast, transects with the native C. scandens had higher pH, sand content, and soil magnesium and lower organic matter compared to transects where it was absent. Celastrus orbiculatus appears to be a generalist liana since it often occurs with native lianas. Celastrus orbiculatus poses a substantial threat to mature forests as it will persist in the understory until a canopy gap or other disturbance provides the light and supports necessary for it to ascend to the canopy and damage tree species. As a result, these forests should be monitored by land managers so that C. orbiculatus eradication can occur while invasions are at low densities and restricted to the ground layer.

  13. Brood comb as a humidity buffer in honeybee nests

    NASA Astrophysics Data System (ADS)

    Ellis, Michael B.; Nicolson, Sue W.; Crewe, Robin M.; Dietemann, Vincent

    2010-04-01

    Adverse environmental conditions can be evaded, tolerated or modified in order for an organism to survive. During their development, some insect larvae spin cocoons which, in addition to protecting their occupants against predators, modify microclimatic conditions, thus facilitating thermoregulation or reducing evaporative water loss. Silk cocoons are spun by honeybee ( Apis mellifera) larvae and subsequently incorporated into the cell walls of the wax combs in which they develop. The accumulation of this hygroscopic silk in the thousands of cells used for brood rearing may significantly affect nest homeostasis by buffering humidity fluctuations. This study investigates the extent to which the comb may influence homeostasis by quantifying the hygroscopic capacity of the cocoons spun by honeybee larvae. When comb containing cocoons was placed at high humidity, it absorbed 11% of its own mass in water within 4 days. Newly drawn comb composed of hydrophobic wax and devoid of cocoons absorbed only 3% of its own mass. Therefore, the accumulation of cocoons in the comb may increase brood survivorship by maintaining a high and stable humidity in the cells.

  14. Superconducting composite with multilayer patterns and multiple buffer layers

    DOEpatents

    Wu, Xin D.; Muenchausen, Ross E.

    1993-01-01

    An article of manufacture including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superco n FIELD OF THE INVENTION The present invention relates to the field of superconducting articles having two distinct regions of superconductive material with differing in-plane orientations whereby the conductivity across the boundary between the two regions can be tailored. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  15. Inhibition of Listeria monocytogenes by Buffered Dry Vinegar in Reduced-Sodium Ready-to-Eat Uncured Turkey Stored at 4°C.

    PubMed

    Badvela, Mani K; Dickson, James S; Sebranek, Joseph G; Schroeder, William D

    2016-08-01

    A reduced-sodium ready-to-eat (RTE) uncured turkey was manufactured with buffered dry vinegar treatments to validate the inhibition of Listeria monocytogenes and spoilage microflora and to determine the effects on sensory and quality attributes. Samples were stored at 4°C for 12 weeks, and the study was independently replicated three times. Two different five-strain inocula of L. monocytogenes obtained from different sources were used for evaluating the efficacy of the buffered dry vinegar treatments. The results showed that 0.6 and 0.8% buffered dry vinegar with a sodium base (BDV-SB) and buffered dry vinegar with a potassium base (BDV-PB) at 0.7 and 0.9% controlled L. monocytogenes for 12 weeks. The untreated control product containing no buffered dry vinegar showed >1 log increase in L. monocytogenes populations counts at the end of 2 weeks. Statistical analysis confirmed that the dry vinegar treatments inhibited (P > 0.05) the growth of L. monocytogenes compared with the untreated control. No significant differences (P > 0.05) were seen in the inhibition of L. monocytogenes between the two different five-strain inocula. Instrumental color results showed no significant differences between the treatments. Purge loss results showed no significant differences between the dry vinegar treatments, but significant differences were seen between the untreated control and dry vinegar treatments at a few testing intervals. The overall results indicated that the dry vinegar ingredients (6.66 to 8.83 mM acetic acid in the finished product) were effective in inhibiting L. monocytogenes obtained from multiple sources in reduced-sodium RTE uncured turkey stored at 4°C without adversely impacting the quality attributes. PMID:27497127

  16. HOW EFFECTIVE ARE RIPARIAN BUFFERS IN CONTROLLING NUTRIENT EXPORT FROM AGRICULTURAL WATERSHEDS?

    EPA Science Inventory

    Riparian buffers are being established in many parts of the world as part of nonpoint source pollution management strategies. A large number of studies have documented the potential of riparian buffers to reduce export of nutrients, especially nitrogen, in shallow ground water of...

  17. Buffer AVL Alone Does Not Inactivate Ebola Virus in a Representative Clinical Sample Type

    PubMed Central

    Weller, Simon A.; Phelps, Amanda; Eastaugh, Lin; Ngugi, Sarah; O'Brien, Lyn M.; Steward, Jackie; Lonsdale, Steve G.; Lever, Mark S.

    2015-01-01

    Rapid inactivation of Ebola virus (EBOV) is crucial for high-throughput testing of clinical samples in low-resource, outbreak scenarios. The EBOV inactivation efficacy of Buffer AVL (Qiagen) was tested against marmoset serum (EBOV concentration of 1 × 108 50% tissue culture infective dose per milliliter [TCID50 · ml−1]) and murine blood (EBOV concentration of 1 × 107 TCID50 · ml−1) at 4:1 vol/vol buffer/sample ratios. Posttreatment cell culture and enzyme-linked immunosorbent assay (ELISA) analysis indicated that treatment with Buffer AVL did not inactivate EBOV in 67% of samples, indicating that Buffer AVL, which is designed for RNA extraction and not virus inactivation, cannot be guaranteed to inactivate EBOV in diagnostic samples. Murine blood samples treated with ethanol (4:1 [vol/vol] ethanol/sample) or heat (60°C for 15 min) also showed no viral inactivation in 67% or 100% of samples, respectively. However, combined Buffer AVL and ethanol or Buffer AVL and heat treatments showed total viral inactivation in 100% of samples tested. The Buffer AVL plus ethanol and Buffer AVL plus heat treatments were also shown not to affect the extraction of PCR quality RNA from EBOV-spiked murine blood samples. PMID:26179307

  18. INFLUENCE OF ORGANIC BUFFERS ON BACTERIOCIN PRODUCTION BY STREPTOCOCCUS THERMOPHILUS ST110

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of the organic buffer salts MES, MOPS and PIPES on the growth of S. thermophilus ST110, medium pH and accumulation of the antipediococcal bacteriocin thermophilin 110 were evaluated in whey permeate media over a period of 24 h. In non buffered medium, thermophilin 110 production at 37°C ...

  19. Managing soil nitrate with cover crops and buffer strips in Sicilian vineyards

    NASA Astrophysics Data System (ADS)

    Novara, A.; Gristina, L.; Guaitoli, F.; Santoro, A.; Cerdà, A.

    2013-08-01

    When soil nitrate levels are low, plants suffer nitrogen (N) deficiency but when the levels are excessive, soil nitrates can pollute surface and subsurface waters. Strategies to reduce the nitrate pollution are necessary to reach a sustainable use of resources such as soil, water and plant. Buffer strips and cover crops can contribute to the management of soil nitrates, but little is known of their effectiveness in semiarid vineyards plantations. The research was carried out in the south coast of Sicily (Italy) to evaluate nitrate trends in a vineyard managed both conventionally and using two different cover crops (Triticum durum and Vicia sativa cover crop). A 10 m-wide buffer strip was seeded with Lolium perenne at the bottom of the vineyard. Soil nitrate was measured monthly and nitrate movement was monitored by application of a 15N tracer to a narrow strip between the bottom of vineyard and the buffer and non-buffer strips. Lolium perenne biomass yield in the buffer strips and its isotopic nitrogen content were monitored. Vicia sativa cover crop management contributed with an excess of nitrogen, and the soil management determined the nitrogen content at the buffer areas. A 6 m buffer strip reduced the nitrate by 42% with and by 46% with a 9 m buffer strip. Thanks to catch crops, farmers can manage the N content and its distribution into the soil over the year, can reduced fertilizer wastage and reduce N pollution of surface and groundwater.

  20. Influence of Herbaceous Riparian Buffers on Channelized Headwater Streams in Central Ohio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbaceous riparian buffers are a widely used conservation practice in the United States for reducing nutrient, pesticide, and sediment loadings in agricultural streams. The importance of forested riparian buffers for headwater streams has been documented, but the ecological impacts of herbaceous ri...