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Sample records for acetate buffer solution

  1. Graphene ultrathin film electrode for detection of lead ions in acetate buffer solution.

    PubMed

    Wang, Zhaomeng; Liu, Erjia

    2013-01-15

    Few-layer graphene ultrathin films were synthesized via solid-state carbon diffusion from amorphous carbon (a-C) thin layers sputtering coated on Si substrates with or without a SiO(2) layer, which an a-C layer was covered by a nickel (Ni) layer as a catalyst. When the Ni/a-C bilayer coated samples were heated at 1000°C the carbon (C) atoms from the a-C layers diffused into the top Ni layers to form a C rich surface. Upon rapid cooling, the C atoms accumulated on the surface of the Ni layers and formed graphene ultrathin films through nucleation and growth processes. The formation of graphene ultrathin films was confirmed by Raman spectroscopy, high resolution transmission electron microscopy (HR-TEM), electron diffraction, field-emission scanning electron microscopy (FE-SEM) and 4-point probe. The synthesized graphene ultrathin films were used as working electrodes for detection of trace heavy metal ions (Pb(2+), as low as 7 nM) in acetate buffer solutions (pH 5.3) using square wave anodic stripping voltammetry (SWASV). The effects of substrate surface condition and Ni layer thickness on the structure and electrochemical properties of graphene ultrathin film electrodes were investigated in detail. Compared to conventional diamond-like carbon (DLC) electrodes, the graphene electrodes developed in this study had better repeatability, higher sensitivity and higher resistance to passivation caused by surface active species.

  2. Effect of acetate and carbonate buffers on the photolysis of riboflavin in aqueous solution: a kinetic study.

    PubMed

    Ahmad, Iqbal; Anwar, Zubair; Iqbal, Kefi; Ali, Syed Abid; Mirza, Tania; Khurshid, Adeela; Khurshid, Aqeela; Arsalan, Adeel

    2014-06-01

    The photolysis of riboflavin (RF) in the presence of acetate buffer (pH 3.8-5.6) and carbonate buffer (pH 9.2-10.8) has been studied using a multicomponent spectrophotometric method for the simultaneous assay of RF and its photoproducts. Acetate and carbonate buffers have been found to catalyze the photolysis reaction of RF. The apparent first-order rate constants for the acetate-catalyzed reaction range from 0.20 to 2.86 × 10(-4) s(-1) and for the carbonate-catalyzed reaction from 3.33 to 15.89 × 10(-4) s(-1). The second-order rate constants for the interaction of RF with the acetate and the carbonate ions range from 2.04 to 4.33 × 10(-4) M(-1) s(-1) and from 3.71 to 11.80 × 10(-4) M(-1) s(-1), respectively. The k-pH profile for the acetate-catalyzed reaction is bell shaped and for the carbonate-catalyzed reaction a steep curve. Both HCO3(-) and CO3(2-) ions are involved in the catalysis of the photolysis reaction in alkaline solution. The rate constants for the HCO3(-) and CO3(2-) ions catalyzed reactions are 0.72 and 1.38 × 10(-3) M(-1) s(-1), respectively, indicating a major role of CO3(2-) ions in the catalysis reaction. The loss of RF fluorescence in acetate buffer suggests an interaction between RF and acetate ions to promote the photolysis reaction. The optimum stability of RF solutions is observed in the pH range 5-6, which is suitable for pharmaceutical preparations.

  3. Influence of Alkylammonium Acetate Buffers on Protein-Ligand Noncovalent Interactions Using Native Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhuang, Xiaoyu; Gavriilidou, Agni F. M.; Zenobi, Renato

    2017-02-01

    We investigate the influence of three volatile alkylammonium acetate buffers on binding affinities for protein-ligand interactions determined by native electrospray ionization-mass spectrometry (ESI-MS). Four different types of proteins were chosen for this study. A charge-reduction effect was observed for all the cases studied, in comparison to the ions formed in ammonium acetate solution. When increasing the collision energy, the complexes of trypsin and the ligand were found to be more stable when sprayed from alkylammonium acetate buffers than from ammonium acetate. The determined dissociation constant (Kd) also exhibited a drop (up to 40%) when ammonium acetate was replaced by alkylammonium acetate buffers for the case of lysozyme and the ligand. The prospective uses of these ammonium acetate analogs in native ESI-MS are discussed in this paper as well.

  4. 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.

  5. 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)

  6. 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.

  7. Disproportionation Kinetics of Hypoiodous Acid As Catalyzed and Suppressed by Acetic Acid-Acetate Buffer.

    PubMed

    Urbansky, Edward T.; Cooper, Brian T.; Margerum, Dale W.

    1997-03-26

    The kinetics of the disproportionation of hypoiodous acid to give iodine and iodate ion (5HOI right harpoon over left harpoon 2I(2) + IO(3)(-) + H(+) + 2H(2)O) are investigated in aqueous acetic acid-sodium acetate buffer. The rate of iodine formation is followed photometrically at -log [H(+)] = 3.50, 4.00, 4.50, and 5.00, &mgr; = 0.50 M (NaClO(4)), and 25.0 degrees C. Both catalytic and inhibitory buffer effects are observed. The first process is proposed to be a disproportionation of iodine(I) to give HOIO and I(-); the iodide then reacts with HOI to give I(2). The reactive species (acetato-O)iodine(I), CH(3)CO(2)I, is postulated to increase the rate by assisting in the formation of I(2)O, a steady-state species that hydrolyzes to give HOIO and I(2). Inhibition is postulated to result from the formation of the stable ion bis(acetato-O)iodate(I), (CH(3)CO(2))(2)I(-), as buffer concentration is increased. This species is observed spectrophotometrically with a UV absorption shoulder (lambda = 266 nm; epsilon = 530 M(-)(1) cm(-)(1)). The second process is proposed to be a disproportionation of HOIO to give IO(3)(-) and I(2). Above 1 M total buffer, the reaction becomes reversible with less than 90% I(2) formation. Rate and equilibrium constants are resolved and reported for the proposed mechanism.

  8. A new strategy to stabilize oxytocin in aqueous solutions: I. The effects of divalent metal ions and citrate buffer.

    PubMed

    Avanti, Christina; Amorij, Jean-Pierre; Setyaningsih, Dewi; Hawe, Andrea; Jiskoot, Wim; Visser, Jan; Kedrov, Alexej; Driessen, Arnold J M; Hinrichs, Wouter L J; Frijlink, Henderik W

    2011-06-01

    In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. Both monovalent metal ions (Na(+) and K(+)) and divalent metal ions (Ca(2+), Mg(2+), and Zn(2+)) were tested all as chloride salts. The effect of combinations of buffers and metal ions on the stability of aqueous oxytocin solutions was determined by RP-HPLC and HP-SEC after 4 weeks of storage at either 4°C or 55°C. Addition of sodium or potassium ions to acetate- or citrate-buffered solutions did not increase stability, nor did the addition of divalent metal ions to acetate buffer. However, the stability of aqueous oxytocin in aqueous formulations was improved in the presence of 5 and 10 mM citrate buffer in combination with at least 2 mM CaCl(2), MgCl(2), or ZnCl(2) and depended on the divalent metal ion concentration. Isothermal titration calorimetric measurements were predictive for the stabilization effects observed during the stability study. Formulations in citrate buffer that had an improved stability displayed a strong interaction between oxytocin and Ca(2+), Mg(2+), or Zn(2+), while formulations in acetate buffer did not. In conclusion, our study shows that divalent metal ions in combination with citrate buffer strongly improved the stability of oxytocin in aqueous solutions.

  9. Buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions: from protein buffer capacity prediction to bioprocess applications.

    PubMed

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

    2015-04-01

    Protein therapeutics, including monoclonal antibodies (mAbs), have significant buffering capacity, particularly at concentrations>50 mg/mL. This report addresses pH-related issues critical to adoption of self-buffered monoclonal antibody formulations. We evaluated solution conditions with protein concentrations ranging from 50 to 250 mg/mL. Samples were both buffer-free and conventionally buffered with citrate. Samples were non-isotonic or adjusted for isotonicity with NaCl or trehalose. Studies included accelerated temperature stability tests, shaking stability studies, and pH changes in infusion media as protein concentrate is added. We present averaged buffering slopes of capacity that can be applied to any mAb and present a general method for calculating buffering capacity of buffer-free, highly concentrated antibody liquid formulations. In temperature stability tests, neither buffer-free nor conventionally buffered solution conditions showed significant pH changes. Conventionally buffered solutions showed significantly higher opalescence than buffer-free ones. In general, buffer-free solution conditions showed less aggregation than conventionally buffered solutions. Shaking stability tests showed no differences between buffer-free and conventionally buffered solutions. "In-use" preparation experiments showed that pH in infusion bag medium can rapidly approximate that of self-buffered protein concentrate as concentrate is added. In summary, the buffer capacity of proteins can be predicted and buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions.

  10. What's in your buffer? Solute altered millisecond motions detected by solution NMR.

    PubMed

    Wong, Madeline; Khirich, Gennady; Loria, J Patrick

    2013-09-17

    To date, little work has been conducted on the relationship between solute and buffer molecules and conformational exchange motion in enzymes. This study uses solution NMR to examine the effects of phosphate, sulfate, and acetate in comparison to MES- and HEPES-buffered references on the chemical shift perturbation and millisecond, chemical, or conformational exchange motions in the enzyme ribonuclease A (RNase A), triosephosphate isomerase (TIM) and HisF. The results indicate that addition of these solutes has a small effect on (1)H and (15)N chemical shifts for RNase A and TIM but a significant effect for HisF. For RNase A and TIM, Carr-Purcell-Meiboom-Gill relaxation dispersion experiments, however, show significant solute-dependent changes in conformational exchange motions. Some residues show loss of millisecond motions relative to the reference sample upon addition of solute, whereas others experience an enhancement. Comparison of exchange parameters obtained from fits of dispersion data indicates changes in either or both equilibrium populations and chemical shifts between conformations. Furthermore, the exchange kinetics are altered in many cases. The results demonstrate that common solute molecules can alter observed enzyme millisecond motions and play a more active role than what is routinely believed.

  11. Ozone decomposition in aqueous acetate solutions

    SciTech Connect

    Sehested, K.; Holcman, J.; Bjergbakke, E.; Hart, E.J.

    1987-01-01

    The acetate radical ion reacts with ozone with a rate constant of k = (1.5 +/- 0.5) x 10Z dmT mol s . The products from this reaction are CO2, HCHO, and O2 . By subsequent reaction of the peroxy radical with ozone the acetate radical ion is regenerated through the OH radical. A chain decomposition of ozone takes place. It terminates when the acetate radical ion reacts with oxygen forming the unreactive peroxy acetate radical. The chain is rather short as oxygen is developed, as a result of the ozone consumption. The inhibiting effect of acetate on the ozone decay is rationalized by OH scavenging by acetate and successive reaction of the acetate radical ion with oxygen. Some products from the bimolecular disappearance of the peroxy acetate radicals, however, react further with ozone, reducing the effectiveness of the stabilization.

  12. 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.

  13. Application of acetate buffer in pH adjustment of sorghum mash and its influence on fuel ethanol fermentation.

    PubMed

    Zhao, Renyong; Bean, Scott R; Crozier-Dodson, Beth Ann; Fung, Daniel Y C; Wang, Donghai

    2009-01-01

    A 2 M sodium acetate buffer at pH 4.2 was tried to simplify the step of pH adjustment in a laboratory dry-grind procedure. Ethanol yields or conversion efficiencies of 18 sorghum hybrids improved significantly with 2.0-5.9% (3.9% on average) of relative increases when the method of pH adjustment changed from traditional HCl to the acetate buffer. Ethanol yields obtained using the two methods were highly correlated (R (2) = 0.96, P < 0.0001), indicating that the acetate buffer did not influence resolution of the procedure to differentiate sorghum hybrids varying in fermentation quality. Acetate retarded the growth of Saccharomyces cerevisiae, but did not affect the overall fermentation rate. With 41-47 mM of undissociated acetic acid in mash of a sorghum hybrid at pH 4.7, rates of glucose consumption and ethanol production were inhibited during exponential phase but promoted during stationary phase. The maximum growth rate constants (mu(max)) were 0.42 and 0.32 h(-1) for cells grown in mashes with pH adjusted by HCl and the acetate buffer, respectively. Viable cell counts of yeast in mashes with pH adjusted by the acetate buffer were 36% lower than those in mashes adjusted by HCl during stationary phase. Coupled to a 5.3% relative increase in ethanol, a 43.6% relative decrease in glycerol was observed, when the acetate buffer was substituted for HCl. Acetate helped to transfer glucose to ethanol more efficiently. The strain tested did not use acetic acid as carbon source. It was suggested that decreased levels of ATP under acetate stress stimulate glycolysis to ethanol formation, increasing its yield at the expense of biomass and glycerol production.

  14. 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)

  15. Effect of Tris-acetate buffer on endotoxin removal from human-like collagen used biomaterials.

    PubMed

    Zhang, Huizhi; Fan, Daidi; Deng, Jianjun; Zhu, Chenghui; Hui, Junfeng; Ma, Xiaoxuan

    2014-09-01

    Protein preparation, which has active ingredients designated for the use of biomaterials and therapeutical protein, is obtained by genetic engineering, but products of genetic engineering are often contaminated by endotoxins. Because endotoxin is a ubiquitous and potent proinflammatory agent, endotoxin removal or depletion from protein is essential for researching any biomaterials. In this study, we have used Tris-acetate (TA) buffer of neutral pH value to evaluate endotoxins absorbed on the Pierce high-capacity endotoxin removal resin. The effects of TA buffer on pH, ionic strength, incubation time as well as human-like collagen (HLC) concentration on eliminating endotoxins are investigated. In the present experiments, we design an optimal method for TA buffer to remove endotoxin from recombinant collagen and use a chromogenic tachypleus amebocyte lysate (TAL) test kit to measure the endotoxin level of HLC. The present results show that, the endotoxins of HLC is dropped to 8.3EU/ml at 25 mM TA buffer (pH7.8) with 150 mM NaCl when setting incubation time at 6h, and HLC recovery is about 96%. Under this experimental condition, it is proved to exhibit high efficiencies of both endotoxin removal and collagen recovery. The structure of treated HLC was explored by Transmission Electron Microscopy (TEM), demonstrating that the property and structure of HLC treated by TA buffer are maintained. Compared to the most widely used endotoxin removal method, Triton X-114 extraction, using TA buffer can obtain the non-toxic HLC without extra treatment for removing the toxic substances in Triton X-114. In addition, the present study aims at establishing a foundation for further work in laboratory animal science and providing a foundation for medical grade biomaterials.

  16. Use of buffered hypochlorite solution for disinfecting fibrescopes.

    PubMed

    Coates, D; Death, J E

    1982-03-01

    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.

  17. 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.

  18. A procedure for the joint evaluation of substrate partitioning and kinetic parameters for reactions catalyzed by enzymes in reverse micellar solutions. I. Hydrolysis of 2-naphthyl acetate catalyzed by lipase in sodium 1,4-bis(2-ethylhexyl) sulphosuccinate (AOT)/buffer/heptane.

    PubMed

    Aguilar, L F; Abuin, E; Lissi, E

    2001-04-15

    A simple method useful for the joint evaluation of substrate partitioning and kinetic parameters for reactions catalyzed by enzymes entrapped in reverse micelles is proposed. The method is applied to the hydrolysis of 2-naphthyl acetate (2-NA) catalyzed by lipase in sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (AOT)/buffer/heptane reverse micellar solutions. In the presence of micelles, the relationship between the initial reaction rate and the analytical concentration of 2-NA was dependent on AOT concentration at a constant W ([water]/[AOT]) value. The dependence of the initial reaction rate profiles with [AOT] was analyzed according with the method proposed to obtain the partition constant of 2-NA between the micelles and the external solvent, Kp. A value of Kp = 2.7 L mol(-1) was obtained irrespective of the water content of the micelles (W from 5 to 20). The catalytic rate constant kcat in the micellar solutions was independent of [AOT] but slightly decreased with an increase in W from 2 x 10(-6) mol g(-1) s(-1) at W = 5 to 1.2 x 10(-6) mol g(-1) s(-1) at W = 20. The apparent Michaelis constant determined in terms of the analytical concentration of 2-NA increased with [AOT] at a given W and moderately decreased with W at a fixed [AOT]. The increase with [AOT] is accounted for by considering the partitioning of the substrate. After correction for the partitioning of 2-NA values of (Km)corr were obtained as 3.9 x 10(-3) mol L(-1) (W = 5), 4.6 x 10(-3) mol L(-1) (W = 10), 2.3 x 10(-3) mol L(-1) (W = 15), and 1.7 x 10(-3) mol L(-1) (W = 20). The rate parameters in the aqueous phase in the absence of micelles, were obtained as (kcat)aq = 7.9 x 10(-6) mol g(-1) s(-1) and (Km)aq = 2.5 x 10(-3) mol L(-1). In order to compare the efficiency of the enzyme in the micellar solution with that in aqueous phase, the values of (Km)corr were in turn corrected to take into account differences in the substrate activity, obtaining so a set of (Km)*corr values. The efficiency of the

  19. Application of Acetate Buffer in pH Adjustment of Mash and its Influence on Fuel Ethanol Fermentation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A 2M sodium acetate buffer at pH 4.2 was used to adjust pH of liquefied mashes in a simultaneous saccharification and fermentation (SSF) procedure. Although 5 mL of the buffer did not bring the pH values of the mashes (~100 mL) from a sorghum hybrid to 4.2, it kept the system stable (pH from 4.7 to ...

  20. Buffered lidocaine and bupivacaine mixture - the ideal local anesthetic solution?

    PubMed

    Best, Corliss A; Best, Alyssa A; Best, Timothy J; Hamilton, Danielle A

    2015-01-01

    The use of injectable local anesthetic solutions to facilitate pain-free surgery is an integral component of many procedures performed by the plastic surgeon. In many instances, a solution that has both rapid onset and prolonged duration of analgesia is optimal. A combination of lidocaine and bupivacaine, plain or with epinephrine, is readily available in most Canadian health care settings where such procedures are performed, and fulfills these criteria. However, commercially available solutions of both medications are acidic and cause a burning sensation on injection. Buffering to neutral pH with sodium bicarbonate is a practical method to mitigate the burning sensation, and has the added benefit of increasing the fraction of nonionized lipid soluble drug available. The authors report on the proportions of the three drugs to yield a neutral pH, and the results of an initial survey regarding the use of the combined solution with epinephrine in hand surgery.

  1. Advanced titania buffer layer architectures prepared by chemical solution deposition

    NASA Astrophysics Data System (ADS)

    Kunert, J.; Bäcker, M.; Brunkahl, O.; Wesolowski, D.; Edney, C.; Clem, P.; Thomas, N.; Liersch, A.

    2011-08-01

    Chemical solution deposition (CSD) was used to grow high-quality (100) oriented films of SrTiO3 (STO) on CSD CaTiO3 (CTO), Ba0.1Ca0.9TiO3 (BCT) and STO seed and template layers. These template films bridge the lattice misfit between STO and the nickel-tungsten (NiW) substrate, assisting in dense growth of textured STO. Additional niobium (Nb) doping of the STO buffer layer reduces oxygen diffusion which is necessary to avoid undesired oxidation of the NiW. The investigated templates offer suitable alternatives to established standard buffer systems like La2Zr2O7 (LZO) and CeO2 for coated conductors.

  2. Viscometric study of chitosan solutions in acetic acid/sodium acetate and acetic acid/sodium chloride.

    PubMed

    Costa, Cristiane N; Teixeira, Viviane G; Delpech, Marcia C; Souza, Josefa Virginia S; Costa, Marcos A S

    2015-11-20

    A viscometric study was carried out at 25°C to assess the physical-chemical behavior in solution and the mean viscometric molar mass (M¯v) of chitosan solutions with different deacetylation degrees, in two solvent mixtures: medium 1-acetic acid 0.3mol/L and sodium acetate 0.2mol/L; and medium 2-acetic acid 0.1mol/L and sodium chloride 0.2mol/L. Different equations were employed, by graphical extrapolation, to calculate the intrinsic viscosities [η] and the viscometric constants, to reveal the solvent's quality: Huggins (H), Kraemer (K) and Schulz-Blaschke (SB). For single-point determination, the equations used were SB, Solomon-Ciuta (SC) and Deb-Chanterjee (DC), resulting in a faster form of analysis. The values of ̄M¯v were calculated by applying the equation of Mark-Houwink-Sakurada. The SB and SC equations were most suitable for single-point determination of [η] and ̄M¯v and the Schulz-Blachke constant (kSB), equal to 0.28, already utilized for various systems, can also be employed to analyze chitosan solutions under the conditions studied.

  3. 21 CFR 522.960b - Flumethasone acetate solution.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Flumethasone acetate solution. 522.960b Section 522.960b Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IMPLANTATION OR INJECTABLE DOSAGE FORM NEW ANIMAL...

  4. ACCURATE CHEMICAL MASTER EQUATION SOLUTION USING MULTI-FINITE BUFFERS

    PubMed Central

    Cao, Youfang; Terebus, Anna; Liang, Jie

    2016-01-01

    The discrete chemical master equation (dCME) provides a fundamental framework for studying stochasticity in mesoscopic networks. Because of the multi-scale nature of many networks where reaction rates have large disparity, directly solving dCMEs is intractable due to the exploding size of the state space. It is important to truncate the state space effectively with quantified errors, so accurate solutions can be computed. It is also important to know if all major probabilistic peaks have been computed. Here we introduce the Accurate CME (ACME) algorithm for obtaining direct solutions to dCMEs. With multi-finite buffers for reducing the state space by O(n!), exact steady-state and time-evolving network probability landscapes can be computed. We further describe a theoretical framework of aggregating microstates into a smaller number of macrostates by decomposing a network into independent aggregated birth and death processes, and give an a priori method for rapidly determining steady-state truncation errors. The maximal sizes of the finite buffers for a given error tolerance can also be pre-computed without costly trial solutions of dCMEs. We show exactly computed probability landscapes of three multi-scale networks, namely, a 6-node toggle switch, 11-node phage-lambda epigenetic circuit, and 16-node MAPK cascade network, the latter two with no known solutions. We also show how probabilities of rare events can be computed from first-passage times, another class of unsolved problems challenging for simulation-based techniques due to large separations in time scales. Overall, the ACME method enables accurate and efficient solutions of the dCME for a large class of networks. PMID:27761104

  5. ACCURATE CHEMICAL MASTER EQUATION SOLUTION USING MULTI-FINITE BUFFERS.

    PubMed

    Cao, Youfang; Terebus, Anna; Liang, Jie

    2016-01-01

    The discrete chemical master equation (dCME) provides a fundamental framework for studying stochasticity in mesoscopic networks. Because of the multi-scale nature of many networks where reaction rates have large disparity, directly solving dCMEs is intractable due to the exploding size of the state space. It is important to truncate the state space effectively with quantified errors, so accurate solutions can be computed. It is also important to know if all major probabilistic peaks have been computed. Here we introduce the Accurate CME (ACME) algorithm for obtaining direct solutions to dCMEs. With multi-finite buffers for reducing the state space by O(n!), exact steady-state and time-evolving network probability landscapes can be computed. We further describe a theoretical framework of aggregating microstates into a smaller number of macrostates by decomposing a network into independent aggregated birth and death processes, and give an a priori method for rapidly determining steady-state truncation errors. The maximal sizes of the finite buffers for a given error tolerance can also be pre-computed without costly trial solutions of dCMEs. We show exactly computed probability landscapes of three multi-scale networks, namely, a 6-node toggle switch, 11-node phage-lambda epigenetic circuit, and 16-node MAPK cascade network, the latter two with no known solutions. We also show how probabilities of rare events can be computed from first-passage times, another class of unsolved problems challenging for simulation-based techniques due to large separations in time scales. Overall, the ACME method enables accurate and efficient solutions of the dCME for a large class of networks.

  6. Efflux of red cell water into buffered hypertonic solutions.

    PubMed

    OLMSTEAD, E G

    1960-03-01

    Buffered NaCl solutions hypertonic to rabbit serum were prepared and freezing point depressions of each determined after dilution with measured amounts of water. Freezing point depression of these dilutions was a linear function of the amount of water added. One ml. of rabbit red cells was added to each 4 ml. of the hypertonic solutions and after incubation at 38 degrees C. for 30 minutes the mixture was centrifuged and a freezing point depression determined on the supernatant fluid. The amount of water added to the hypertonic solutions by the red cells was calcuated from this freezing point depression. For each decrease in the freezing point of -0.093 degrees C. of the surrounding solution red cells gave up approximately 5 ml. of water per 100 ml. of red cells in the range of -0.560 to -0.930 degrees C. Beyond -0.930 degrees C. the amount of water given up by 100 ml. of red cells fits best a parabolic equation. The maximum of this equation occurred at a freezing point of the hypertonic solution of -2.001 degrees C. at which time the maximum amount of water leaving the red cells would be 39.9 ml. per 100 ml. of red cells. The data suggest that only about 43 per cent of the red cell water is available for exchange into solutions of increasing tonicity.

  7. 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.

  8. Finding the lost open-circuit voltage in polymer solar cells by UV-ozone treatment of the nickel acetate anode buffer layer.

    PubMed

    Wang, Fuzhi; Sun, Gang; Li, Cong; Liu, Jiyan; Hu, Siqian; Zheng, Hua; Tan, Zhan'ao; Li, Yongfang

    2014-06-25

    Efficient polymer solar cells (PSCs) with enhanced open-circuit voltage (Voc) are fabricated by introducing solution-processed and UV-ozone (UVO)-treated nickel acetate (O-NiAc) as an anode buffer layer. According to X-ray photoelectron spectroscopy data, NiAc partially decomposed to NiOOH during the UVO treatment. NiOOH is a dipole species, which leads to an increase in the work function (as confirmed by ultraviolet photoemission spectroscopy), thus benefitting the formation of ohmic contact between the anode and photoactive layer and leading to increased Voc. In addition, the UVO treatment improves the wettability between the substrate and solvent of the active layer, which facilitates the formation of an upper photoactive layer with better morphology. Further, the O-NiAc layer can decrease the series resistance (Rs) and increase the parallel resistance (Rp) of the devices, inducing enhanced Voc in comparison with the as-prepared NiAc-buffered control devices without UVO treatment. For PSCs based on the P3HT:PCBM system, Voc increases from 0.50 to 0.60 V after the NiAc buffer layer undergoes UVO treatment. Similarly, in the P3HT:ICBA system, the Voc value of the device with a UVO-treated NiAc buffer layer increases from 0.78 to 0.88 V, showing an enhanced power conversion efficiency of 6.64%.

  9. Evaporation kinetics of acetic acid-water solutions

    NASA Astrophysics Data System (ADS)

    Duffey, K.; Wong, N.; Saykally, R.; Cohen, R. C.

    2012-12-01

    The transport of water molecules across vapor-liquid interfaces in the atmosphere is a crucial step in the formation and evolution of cloud droplets. Despite decades of study, the effects of solutes on the mechanism and rate of evaporation and condensation remain poorly characterized. The present work aims to determine the effect of atmospherically-relevant solutes on the evaporation rate of water. In our experiments, we create a train of micron-sized droplets and measure their temperature via Raman thermometry as they undergo evaporation without condensation. Analysis of the cooling rate yields the evaporation coefficient (γ). Previous work has shown that inorganic salts have little effect on γ, with surface-adsorbing anions causing a slight reduction in the coefficient from that measured for pure water. Organic acids are ubiquitous in aqueous aerosol and have been shown to disrupt the surface structure of water. Here we describe measurements of the evaporation rate of acetic acid solutions, showing that acetic acid reduces γ to a larger extent than inorganic ions, and that γ decreases with increasing acetic acid concentration.

  10. Effects of sodium acetate buffer on chitosan sponge properties and in vivo degradation in a rat intramuscular model.

    PubMed

    Parker, Ashley Cox; Smith, James Keaton; Reves, Benjamin; Jennings, Jessica Amber; Bumgardner, Joel D; Haggard, Warren O

    2015-02-01

    Chitosan sponges were developed for adjunctive local antibiotic delivery to reduce bacteria in wounds. There is a need to increase sponge degradation for rapid clearance from the wound site during initial wound care. This work examined the effect of using 0.25 M sodium acetate buffers, at pH 4.6 or 5.6, to fabricate sponges with an amorphous chitosan polymer structure. Sponges were evaluated for their crystallinity, thermal, spectroscopic, and morphological properties, in addition to in vitro degradation, and cytocompatibility analysis using normal human dermal fibroblasts. In vivo degradation and biocompatibility were also examined after 4 and 10 days in rat intramuscular tissues. Both buffered chitosan sponge variations exhibited decreases in crystallinity and thermal decomposition temperatures, and increases in surface roughness, which resulted in over 40% increases in degradation over 10 days in vitro compared to the neutral sponges. There were no significant differences between sponges during in vivo degradation over 10 days with respect to histomorphometric analysis of the recovered sponges. These results demonstrated that the acetate buffer did change characteristic chitosan sponge material properties, and increasing the in vivo sponge degradation rate will require balancing material characteristics and processing.

  11. 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.

  12. Corrosion behavior of mild steel in acetic acid solutions

    SciTech Connect

    Singh, M.M.; Gupta, A.

    2000-04-01

    The corrosion behavior of mild steel in acetic acid (CH{sub 3}COOH) solutions was studied by weight loss and potentiostatic polarization techniques. The variation in corrosion rate of mild steel with concentrations of CH{sub 3}COOH, evaluated by weight loss and electrochemical techniques, showed marked resemblance. From both techniques, the maximum corrosion rate was observed for 20% CH{sub 3}COOH solution at all three experimental temperatures (25, 35, and 45 C). Anodic polarization curves showed active-passive behavior at each concentration, except at 80% CH{sub 3}COOH. Critical current density (i{sub c}) passive current density (I{sub n}), primary passivation potential (E{sub pp}), and potential for passivity (E{sub p}) had their highest values in 20% CH{sub 3}COOH solution. With an increase in temperature, while the anodic polarization curves shifted toward higher current density region at each concentration, the passive region became progressively less distinguishable. With the addition of sodium acetate (NaCOOCH{sub 3}) as a supporting electrolyte, the passive range was enlarged substantially. However, the transpassive region commenced at more or less the same potential. Cathodic polarization curves were almost identical irrespective of the concentration of CH{sub 3}COOH or temperature.

  13. A highly selective fluorescent probe for BO3(-) based on acetate derivatives of coumarin in aqueous solution and thimerosal.

    PubMed

    Huo, Fangjun; Wang, Long; Yang, Yutao; Chu, Yueyin; Yin, Caixia; Chao, Jianbin; Zhang, Yongbin; Yan, Xuxiu; Zheng, Anmin; Jin, Shuo; Zhi, Peng

    2013-02-21

    The acetate derivatives of coumarin exhibited a prominent turn-on type signaling behavior toward BO(3)(-) ions over other common anions. Signaling is based on the selective deprotection of acetate groups by perborate, which resulted in significant fluorogenic signaling in an acetate buffered solution (pH 5.0). Interestingly, the detection process makes the raw material of 7-hydroxycoumarin regenerate, and the probe could be applied for the detection of BO(3)(-) of thimerosal. Furthermore, the optical properties of the probe and its BO(3)(-)-induced product were theoretically studied based on density functional theory (DFT) and the time-dependent DFT (TDDFT) explored at the B3LYP/6-311+G (d, p) level.

  14. Influence of phosphate-buffered sucrose solution on early graft function in feline renal autotransplantation.

    PubMed

    Katayama, Masaaki; Okamura, Yasuhiko; Shimamura, Shunsuke; Katayama, Rieko; Kamishina, Hiroaki; Uzuka, Yuji

    2014-10-01

    Graft perfusion with cold heparinized saline has known to induce ischemia and reperfusion injury in feline kidney transplantation. In this study, the effects of phosphate-buffered sucrose solution and heparinized saline solution on early kidney graft function were compared in feline kidney autotransplantation. Perfusion of grafts with or without hypothermic storage with chilled phosphate-buffered sucrose solution prevented ischemia and reperfusion injury despite a very short ischemic time. The results of our study suggest that phosphate-buffered sucrose perfusion and storage solution should be effective to reduce ischemia and reperfusion injury despite a very short ischemic time in feline kidney transplantation.

  15. Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

    NASA Astrophysics Data System (ADS)

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-08-01

    To maintain local pH levels near the electrode during electrochemical reactions, the use of buffer solutions is effective. Nevertheless, the critical effects of the buffer concentration on electrocatalytic performances have not been discussed in detail. In this study, two fundamental electrochemical reactions, oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR), on a platinum rotating disk electrode are chosen as model gas-related aqueous electrochemical reactions at various phosphate concentrations. Our detailed investigations revealed that the kinetic and limiting diffusion current densities for both the ORR and HOR logarithmically decrease with increasing solute concentration (log |jORR | = - 0.39 c + 0.92 , log |jHOR | = - 0.35 c + 0.73) . To clarify the physical aspects of this phenomenon, the electrolyte characteristics are addressed: with increasing phosphate concentration, the gas solubility decrease, the kinematic viscosity of the solution increase and the diffusion coefficient of the dissolved gases decrease. The simulated limiting diffusion currents using the aforementioned parameters match the measured ones very well (log |jORR | = - 0.43 c + 0.99 , log |jHOR | = - 0.40 c + 0.54) , accurately describing the consequences of the electrolyte concentration. These alterations of the electrolyte properties associated with the solute concentration are universally applicable to other aqueous gas-related electrochemical reactions because the currents are purely determined by mass transfer of the dissolved gases.

  16. Photocatalytic decomposition of cortisone acetate in aqueous solution.

    PubMed

    Romão, Joana Sobral; Hamdy, Mohamed S; Mul, Guido; Baltrusaitis, Jonas

    2015-01-23

    The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L(-1)min(-1) at 10 mg L(-1) concentration, using the following heterogeneous photocatalysts in decreasing order of their catalytic activity: ZnO>Evonik TiO2 P25>Hombikat TiO2>WO3. Due to the lack of ZnO stability in aqueous solutions, TiO2 P25 was chosen for further experiments. The decomposition reaction was found to be pseudo-first order and the rate constant decreased as a function of increasing initial CA concentration. Changing the initial pH of the CA solution did not affect the reaction rate significantly. The decomposition reaction in the presence of the oxidizing sacrificial agent sodium persulfate showed an observed decomposition rate constant of 0.004 min(-1), lower than that obtained for TiO2 P25 (0.040 min(-1)). The highest photocatalytic degradation rate constant was obtained combining both TiO2 P25 and S2O8(2-) (0.071 min(-1)) showing a synergistic effect. No reactive intermediates were detected using LC-MS showing fast photocatalytic decomposition kinetics of CA.

  17. Rheological study of chitosan acetate solutions containing chitin nanofibrils.

    PubMed

    Mikešová, Jana; Hašek, Jindřich; Tishchenko, Galina; Morganti, Pierfrancesco

    2014-11-04

    Rheological properties of chitosan acetate solutions containing chitin nanofibrils (n-chitin) and biocompatible plasticizers intended for preparation of biodegradable films are reported in the steady, oscillatory and transient shear flow. The experiments were performed on slurries with an optimum proportion of 65/35 wt.% between chitosan and n-chitin in the films which was determined from our results of mechanical properties and absorption of water vapor. The time-dependent dynamic experiments revealed the chitin nanofibrils as an effective "gelling agent" of chitosan phase. The phenomenon is explained by a chitosan-like surface of n-chitin and by the interactions inducing orientational cooperativity of chitosan molecules dissolved in close neighborhood of the anisotropic chitin nanofibrils. Additions of glycerol or poly(ethylene glycol), improving mechanical properties of the films, delay significantly the onset of gelation of chitosan/n-chitin slurries. The effect is induced by an increase in viscosity of the slurries and by their enhanced chaotropic character.

  18. [Influence of buffer solutions on the performance of microbial fuel cell electricity generation].

    PubMed

    Qiang, Lin; Yuan, Lin-jiang; Ding, Qing

    2011-05-01

    Microbial fuel cell (MFC) is a potential green technology due to its application in wastewater treatment and renewable energy generation. Phosphate buffer solution (PBS) has been commonly used in MFC studies to maintain a suitable pH for electricity generating bacteria and/or to increase the solution conductivity. However, it has some drawbacks using PBS in MFC: One is that the addition of a high concentration of phosphate buffer in MFCs is expensive, especially for the application in wastewater treatment; the other is that phosphates can contribute to the eutrophication conditions of water bodies if the effluents are discharged without the removal of phosphates. By adding PBS buffer as the comparison, the study investigated the effect of borax buffer and in the absence of buffer on the performance of electrical power, coulomb efficiency and effluent pH. 200 mmol/L PBS was the best, conductivity was 1.973 mS/cm,the maximum power density was 36.4 mW/m2 and the maximum coulomb efficiency was 2.92%, effluent pH was almost at (7.00 +/- 0.05). 100 mmol/L borax buffer solution, conductivity was 1.553 mS/cm; the maximum power density was 26.2 mW/m2 coulomb efficiency of 6.26%, which was 2.14 times to PBS and greatly increased the electron recovery efficiency with the effluent pH was (7.35 +/- 0.05). While free buffer solution conductivity was 0.314 mS/cm, maximum power density was 27.64 mW/m2; coulomb efficiency was 2.82% and the effluent pH of approximately 7.43. The electrolyte which in absence of buffer solution conductivity was 1/6 of adding PBS buffer, 1/5 of borax buffer, while its power density lower 8.76 mW/mr2 than adding PBS and higher 1.24 mW/m2 than borax buffer. The results showed that adding the suitable concentration of borax buffer may improve the electron recovery efficiency and under batch conditions, MFC run successfully without adding buffer solution to MFC.

  19. [Alanine solution as enzyme reaction buffer used in A to O blood group conversion].

    PubMed

    Li, Su-Bo; Zhang, Xue; Zhang, Yin-Ze; Tan, Ying-Xia; Bao, Guo-Qiang; Wang, Ying-Li; Ji, Shou-Ping; Gong, Feng; Gao, Hong-Wei

    2014-06-01

    The aim of this study was to investigate the effect of alanine solution as α-N-acetylgalactosaminidase enzyme reaction buffer on the enzymatic activity of A antigen. The binding ability of α-N-acetylgalactosaminidase with RBC in different reaction buffer such as alanine solution, glycine solution, normal saline (0.9% NaCl), PBS, PCS was detected by Western blot. The results showed that the efficiency of A to O conversion in alanine solution was similar to that in glycine solution, and Western blot confirmed that most of enzymes blinded with RBC in glycine or alanine solution, but few enzymes blinded with RBC in PBS, PCS or normal saline. The evidences indicated that binding of enzyme with RBC was a key element for A to O blood group conversion, while the binding ability of α-N-acetylgalactosaminidase with RBC in alanine or glycine solution was similar. It is concluded that alanine solution can be used as enzyme reaction buffer in A to O blood group conversion. In this buffer, the α-N-acetylgalactosaminidase is closely blinded with RBC and α-N-acetylgalactosaminidase plays efficient enzymatic activity of A antigen.

  20. Comparison of Ring-Buffer-Based Packet Capture Solutions

    SciTech Connect

    Barker, Steven Andrew

    2015-10-01

    Traditional packet-capture solutions using commodity hardware incur a large amount of overhead as packets are copied multiple times by the operating system. This overhead slows sensor systems to a point where they are unable to keep up with high bandwidth traffic, resulting in dropped packets. Incomplete packet capture files hinder network monitoring and incident response efforts. While costly commercial hardware exists to capture high bandwidth traffic, several software-based approaches exist to improve packet capture performance using commodity hardware.

  1. Influence of an acetate- and a lactate-based balanced infusion solution on acid base physiology and hemodynamics: an observational pilot study

    PubMed Central

    2012-01-01

    Background The current pilot study compares the impact of an intravenous infusion of Ringer’s lactate to an acetate-based solution with regard to acid–base balance. The study design included the variables of the Stewart approach and focused on the effective strong ion difference. Because adverse hemodynamic effects have been reported when using acetate buffered solutions in hemodialysis, hemodynamics were also evaluated. Methods Twenty-four women who had undergone abdominal gynecologic surgery and who had received either Ringer’s lactate (Strong Ion Difference 28 mmol/L; n = 12) or an acetate-based solution (Strong Ion Difference 36.8 mmol/L; n = 12) according to an established clinical protocol and its precursor were included in the investigation. After induction of general anesthesia, a set of acid–base variables, hemodynamic values and serum electrolytes was measured three times during the next 120 minutes. Results Patients received a mean dose of 4,054 ± 450 ml of either one or the other of the solutions. In terms of mean arterial blood pressure and norepinephrine requirements there were no differences to observe between the study groups. pH and serum HCO3- concentration decreased slightly but significantly only with Ringer’s lactate. In addition, the acetate-based solution kept the plasma effective strong ion difference more stable than Ringer’s lactate. Conclusions Both of the solutions provided hemodynamic stability. Concerning consistency of acid base parameters none of the solutions seemed to be inferior, either. Whether the slight advantages observed for the acetate-buffered solution in terms of stability of pH and plasma HCO3- are clinically relevant, needs to be investigated in a larger randomized controlled trial. PMID:22769740

  2. Inhibition of protein carbamylation in urea solution using ammonium-containing buffers.

    PubMed

    Sun, Shisheng; Zhou, Jian-Ying; Yang, Weiming; Zhang, Hui

    2014-02-01

    Urea solution is one of the most commonly employed protein denaturants for protease digestion in proteomic studies. However, it has long been recognized that urea solution can cause carbamylation at the N termini of proteins/peptides and at the side chain amino groups of lysine and arginine residues. Protein/peptide carbamylation blocks protease digestion and affects protein identification and quantification in mass spectrometry analysis by blocking peptide amino groups from isotopic/isobaric labeling and changing peptide charge states, retention times, and masses. In addition, protein carbamylation during sample preparation makes it difficult to study in vivo protein carbamylation. In this study, we compared the peptide carbamylation in urea solutions of different buffers and found that ammonium-containing buffers were the most effective buffers to inhibit protein carbamylation in urea solution. The possible mechanism of carbamylation inhibition by ammonium-containing buffers is discussed, and a revised procedure for the protease digestion of proteins in urea and ammonium-containing buffers was developed to facilitate its application in proteomic research.

  3. Oxygen permeability of soft contact lenses in different pH, osmolality and buffering solution

    PubMed Central

    Lee, Se Eun; Kim, So Ra; Park, Mijung

    2015-01-01

    AIM To determine the effect of pH, osmolality, and buffering system on the oxygen permeability (Dk) of soft contact lenses. METHODS Two hydrogel lenses (nelfilcon A and etafilcon A) and 2 silicone hydrogel lenses (lotrafilcon A and balafilcon A) were used in the study. These lenses were incubated in phosphate-buffered saline (PBS) and borate-buffered saline (BBS) solutions adjusted by 0.8 pH increments to a pH in the range of 5.8-9.0 or in hypotonic (280 mOsmol/kg), isotonic (310 mOsmol/kg) and hypertonic (380 mOsmol/kg) PBS solutions. Polarographic method was used for measuring the Dk and lenses were stacked as 4 layers to correct the boundary effect. RESULTS Dk values of all contact lenses measured in BBS solutions were more stable than those in PBS solutions. Especially the etafilcon A lens showed a relative big change compared with other types of contact lenses at the same conditions. When the osmolality of PBS solution increased from hypotonic to hypertonic, Dk of all contact lenses decreased. Variations in Dk existed depending on lens materials, etafilcon A lens was the most affected and nelfilcon A was the least affected by osmolality. CONCLUSION From the result obtained, it is revealed that Dk of contact lenses is changed by the pH, osmolality, and buffering condition of tear. Thus, Dk of contact lens can be varied by the lens wearers' physiological and/or pathological conditions. PMID:26558223

  4. Dopamine-melanin film deposition depends on the used oxidant and buffer solution.

    PubMed

    Bernsmann, Falk; Ball, Vincent; Addiego, Frédéric; Ponche, Arnaud; Michel, Marc; Gracio, José Joaquin de Almeida; Toniazzo, Valérie; Ruch, David

    2011-03-15

    The deposition of "polydopamine" films, from an aqueous solution containing dopamine or other catecholamines, constitutes a new and versatile way to functionalize solid-liquid interfaces. Indeed such films can be deposited on almost all kinds of materials. Their deposition kinetics does not depend markedly on the surface chemistry of the substrate, and the films can reach thickness of a few tens of nanometers in a single reaction step. Up to now, even if a lot is known about the oxidation mechanism of dopamine in solution, only little information is available to describe the deposition mechanism on surfaces either by oxidation in solution or by electrodeposition. The deposition kinetics of melanin was only investigated from dopamine solutions using oxygen or ammonium persulfate as an oxidant and from a tris(hydroxymethyl) aminomethane (Tris) containing buffer solutions at pH 8.5. Many other oxidants could be used, and the buffer agent containing a primary amine group may influence the deposition process. Herein we show that the deposition kinetics of melanin from dopamine containing buffers at pH 8.5 can be markedly modified using Cu(2+) instead of O2 as an oxidant: the deposition kinetics remains linear up to thicknesses of more than 70 nm, whereas the film growth stops at 45 ± 5 nm in the presence of 02. In addition, the films prepared from Cu(2+) containing solutions display an absorption spectrum with defined peaks at 320 and 370 nm, which are absent in the spectra of films prepared in oxygenated solutions. The replacement of Tris buffer by phosphate buffer also has a marked effect on the melanin deposition kinetics.

  5. In Vitro Toxicity and Activity of Dakin’s Solution, Mafenide Acetate, and Amphotericin B on Filamentous Fungi and Human Cells

    DTIC Science & Technology

    2013-08-01

    clinical or in vitro studies did not include molds, but Dakin’s solution has shown activity against Aspergillus flavus and Aspergillus niger but less...clear bottoms (Fisher, Pittsburgh, PA) were exposed to mafenide acetate, amphotericin B, SMAT, and Dakin’s solutions diluted in saline (0.9% NaCl, pH 7.4...in 1· phosphate-buffered saline , pH 7.4 (Sigma). Toxicity of topical solutions was measured using the CellTiter Flour assay (Promega, Madison, WI) as

  6. 76 FR 32366 - Determination That ORLAAM (Levomethadyl Acetate Hydrochloride) Oral Solution, 10 Milligrams...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-06

    ... determined that ORLAAM (levomethadyl acetate hydrochloride (HCl)) oral solution, 10 milligrams (mg... solution, 10 mg/mL, if all other legal and regulatory requirements are met. FOR FURTHER INFORMATION CONTACT... HCl) oral solution, 10 mg/mL, is the subject of NDA 20-315, held by Roxane Laboratories, Inc....

  7. Optimization of buffer solutions to analyze inflammatory cytokines in gingival crevicular fluid by multiplex flow cytometry

    PubMed Central

    Ríos-Lugo, María-Judith; Martin, Conchita; Alarcón, José-Antonio; Esquifino, Ana; Solano, Patricia; Sanz, Mariano

    2015-01-01

    Objective: the aim of this study was to test two buffer solutions in order to attain a reliable and reproducible analysis of inflammatory cytokines (IL-1β, IL-6, TNF-α, OPG, OPN and OC), in gingival crevicular fluid (GCF) by flow cytometry. Material and Methods: GCF samples from healthy volunteers were collected with perio-paper strips and diluted either in phosphate buffered saline (PBS) or Tris-HCl buffer, with and without protease inhibitors (PI). Cytokine immunoassays were carried out by flow cytometry (Luminex Xmap 200) generating standard curves. Results: standards curves generated with the use of phosphate-buffered saline (PBS) demonstrated best adjustment for cytokines IL-1ß, IL-6 and TNF- α levels, when using Tris-HCl (p<0.05). Conclusions: The use of PBS buffer with the addition of PI provided reliable measurements of inflammatory biomarkers in GCF samples of healthy volunteers. Key words:Curve fitting, flow cytometer, immunoassay buffer, crevicular fluid, cytokines. PMID:24880451

  8. Acanthamoeba encystment: multifactorial effects of buffers, biocides, and demulcents present in contact lens care solutions

    PubMed Central

    Kovacs, Christopher J; Lynch, Shawn C; Rah, Marjorie J; Millard, Kimberly A; Morris, Timothy W

    2015-01-01

    Purpose To determine whether agents which are purportedly capable of inducing encystment of Acanthamoeba can recapitulate the signal when tested in differing formulations. Methods In accordance with the International Standard ISO 19045, Acanthamoeba castellanii ATCC 50370 trophozoites were cultured in antibiotic-free axenic medium, treated with test solutions, and encystment rates plus viability were measured via bright field and fluorescent microscopy. Test solutions included phosphate-buffered saline (PBS), borate-buffered saline, biguanide- and hydrogen peroxide (H2O2)-based biocides, propylene glycol (PG) and povidone (POV) ophthalmic demulcents, and one-step H2O2-based contact lens disinfection systems. Results Only PBS solutions with 0.25 ppm polyaminopropyl biguanide (PAPB) and increasing concentrations of PG and POV stimulated A. castellanii encystment in a dose-dependent manner, whereas PBS solutions containing 3% H2O2 and increasing concentrations of PG and POV did not stimulate encystment. Borate-buffered saline and PBS/citrate solutions containing PG also did not stimulate encystment. In addition, no encystment was observed after 24 hours, 7 days, or 14 days of exposures of trophozoites to one-step H2O2 contact lens disinfection products or related solutions. Conclusion The lack of any encystment observed when trophozoites were treated with existing or new one-step H2O2 contact lens care products, as well as when trophozoites were exposed to various related test solutions, confirms that Acanthamoeba encystment is a complex process which depends upon simultaneous contributions of multiple factors including buffers, biocides, and demulcents. PMID:26508829

  9. THE KINETICS OF SAPONIFICATION OF IODOACETIC ACID BY SODIUM HYDROXIDE AND BY CERTAIN ALKALINE BUFFER SOLUTIONS.

    PubMed

    Brdicka, R

    1936-07-20

    1. The rate of the saponification of iodoacetic acid in sodium hydroxide and alkaline buffer solutions yielding glycollic acid was measured by means of Heyrovský's polarographic method. 2. From the bimolecular velocity constants, increasing with the ionic strength of the solution, the Brönsted factor, F, which characterizes the primary salt effect, was calculated. 3. In the borate buffer solutions the monomolecular constants of the saponification were determined which, at values above the pH of neutralization of boric acid, show a proportionality to the concentration of hydroxyl anions. Below the pH of neutralization of boric acid, they are proportional to the concentration of borate anions.

  10. Effect of fluoride in phosphate buffer solution on bonding to artificially carious enamel.

    PubMed

    Wang, Hao; Shimada, Yasushi; Tagami, Junji

    2007-09-01

    The purpose of the present study was to evaluate the effect of fluoride on resin bonding to artificially carious enamel. Specimens from demineralized human enamel sections were prepared using two commercially available adhesives (Clearfil SE Bond, Kuraray; Single Bond, 3M) and a composite resin (Clearfil AP-X, Kuraray) according to manufacturers' instructions. They were then immersed in phosphate buffered saline solution with varied fluoride concentrations at 0, 0.1, 0.5, 1, and 10 ppm. After immersion in each solution for one, three, or seven days, microshear bond strength was measured. The bond strengths of both adhesive systems to artificially carious enamel significantly increased after immersion in fluoride-phosphate buffer solution. Based on the findings obtained, we thus proposed not to remove the white enamel lesions for bonding in the clinic. They might be preserved and treated using fluoride applications.

  11. Thermal decarboxylation of acetate. Part I. The kinetics and mechanism of reaction in aqueous solution

    NASA Astrophysics Data System (ADS)

    Palmer, Donald A.; Drummond, S. E.

    1986-05-01

    In an effort to understand the kinetics of the thermal decarboxylation of acetate and the role of catalysis, a series of laboratory experiments were conducted to measure the rate constants for the decomposition of acetate (acetic acid and sodium acetate) in the presence of titanium, silica, stainless steel, gold, and magnetite. Activation energies for decarboxylation of acetic acid and acetate ion range from about 8 kcal mol -1 in stainless steel vessels to 69 kcal mol -1 in silica tubes. Extrapolated rate constants at 100°C for acetic acid differ by more than fourteen orders of magnitude between the experiments conducted in stainless steel and the catalytically least active titanium vessels. Gold and titanium were the least active catalysts for the acetic acid substrate, while stainless steel, silica, and magnetite showed marked catalytic effects. Methane and carbon dioxide were the predominant reaction products of most of these experiments, although mass spectrometric analyses of the gas phase revealed concentrations of carbon monoxide and hydrocarbons (apparent mass range from 29 to 56) amounting to as much as 55 mole percent of the total volatile products, depending on the catalyst. The reactions were generally first order in acetic acid or acetate ion, except for those involving the acid over silica and magnetite which were zero order. These results and the observed effects of variations in surface area are rationalized in terms of changes in the mode of surface catalysis. The mechanistic assignment is simplified by the existence of three unique straight lines on an isokinetic plot ( i.e., activation enthalpy versus activation entropy) which fit all the respective first- and zeroorder reactions. The results described here provide the nucleus for the discussion in Part II of the role of acetate in the primary migration of methane and the transportation of metals in hydrothermal solutions.

  12. Physicochemical properties and ion-solvent interactions in aqueous sodium, ammonium, and lead acetate solution

    NASA Astrophysics Data System (ADS)

    Deosarkar, S. D.; Mendkudle, M. S.

    2014-09-01

    Densities (ρ), viscosities (η) and refractive indices ( n D) of aqueous sodium acetate (SA), ammonium acetate (AA), and lead acetate (LA) solutions have been measured for different concentrations of salts at 302.15 K. Apparent molar volumes (φv) for studied solutions were calculated from density data, and fitted to Masson's relation and partial molar volume (φ{v/o}) was determined. Viscosity data were fitted to Jones-Dole equation and viscosity A- and B-coefficients were determined. Refractive index and density data were fitted to Lorentz and Lorenz equation and specific refraction ( R D) were calculated. Behavior of various physicochemical properties indicated presence of strong ion-solvent interactions in present systems and the acetate salts structure maker in water.

  13. Buffered Lidocaine Hydrochloride Solution With and Without Epinephrine: Stability in Polypropylene Syringes

    PubMed Central

    Pascuet, Elena; Donnelly, Ronald F; Garceau, Danielle; Vaillancourt, Régis

    2009-01-01

    Background: Pain associated with infiltrating the skin with lidocaine can be reduced by buffering the solution with sodium bicarbonate. Objectives: To determine the physical compatibility and chemical stability of lidocaine hydrochloride solution buffered with 8.4% sodium bicarbonate, with and without epinephrine, packaged in polypropylene syringes and stored at 5°C with protection from light. Methods: Lidocaine solutions (1% and 2%), with and without epinephrine 1:100 000, were diluted 10:1 with 8.4% sodium bicarbonate, packaged in 3-mL polypropylene syringes, and stored at 5°C (range 3°C to 8°C). On each of days 0, 3, 7, 10, 14, 17, 21, 24, and 28, the contents of 3 syringes for each solution of lidocaine combined with epinephrine were collected separately in glass vials and frozen at −70°C for subsequent analysis. In addition, on days 0, 7, 14, 21, and 28, the contents of 3 syringes for each lidocaine solution without epinephrine were collected separately in glass vials and frozen at −70°C for subsequent analysis. Chemical stability was determined with a validated, stability-indicating high-performance liquid chromatography method. Changes in colour, clarity, and pH were used to determine physical compatibility of the solutions. Results: All buffered lidocaine solutions containing epinephrine (1:100 000) retained at least 93.3% of the original concentration of epinephrine and 97.5% of the lidocaine concentration for 7 days when stored at 5°C with protection from light. In contrast, the epinephrine-free solutions retained at least 94.7% of the initial concentration of lidocaine for the duration of the study (28 days). All samples remained clear, colourless, and free of precipitate throughout the study, and there were no significant changes in pH. Conclusion: Extemporaneously prepared buffered lidocaine (1% and 2%) packaged in polypropylene syringes remained stable for up to 28 days when properly refrigerated with protection from light. A 7-day expiry

  14. A Simple Cost Saving Measure: 2.5% Mafenide Acetate Solution

    PubMed Central

    Ibrahim, Amir; Fagan, Shawn; Keaney, Tim; Sarhane, Karim A.; Hursey, Derek A; Chang, Philip; Sheridan, Rob; Ryan, Colleen; Tompkins, Ronald

    2014-01-01

    Objective The optimal concentration of mafenide acetate solution for use in the treatment of burns is unknown. Despite data supporting the use of a 2.5% solution, 5% formulation is traditionally used, and has been the highest costing medication on formulary. The aim of the current study is to evaluate cost and patient outcomes associated with a new policy implementing the use of 2.5% solution in burn patients and restricting the 5% formulation to specific indications only. Methods A retrospective review of all patients receiving mafenide acetate solution at a single pediatric burn hospital was performed before and after the initiation of the new policy on the use of 5% versus 2.5% solution. Duration of therapy, adverse events, cost, incidence of wound infection and bacteremia were analysed. Results In 2009, 69 patients were treated with 5% mafenide acetate solution for a total cost of $125,000 ($1811/patient). In 2010, following the initiation of the policy, 48 patients were treated: 19 received 5% mafenide acetate solution with appropriate indication, while the remaining 29 received 2.5% solution for a total cost of $38,632 ($804/patient). There were no significant changes in the incidence of bacteremia or wound infection. No side effects of either solution were noted. Conclusions Under certain conditions, a 2.5% mafenide acetate solution appears sufficient. In this multinational pediatric burn hospital, the use of a 2.5% solution was not associated with increased bacteremia or wound infection and proved to be more cost-effective. PMID:24043238

  15. Comparison of three buffer solutions for amino acid derivatization and following analysis by liquid chromatography electrospray mass spectrometry.

    PubMed

    Rebane, Riin; Herodes, Koit

    2012-07-06

    For reversed phase separation amino acids are usually derivatized. Several derivatization reactions are carried out at basic pH. In the present work, influence of three basic buffer solutions on liquid chromatography electrospray ionization mass-spectrometric (LC-ESI-MS) analysis of amino acid derivatives was studied. Borate buffer--the most common derivatization buffer--was found to influence ESI ionization up to 23 min retention time. For 9-fluorenylmethylmethoxycarbonyl chloride (Fmoc-Cl derivatization) carbonate buffer should be preferred as it provides higher responses. Hexafluoroisopropanol (HFIP) buffer improves chromatographic peak shapes and responses for diethyl ethoxymethylenemalonate (DEEMM) derivatives.

  16. Hydrogen production in microbial reverse-electrodialysis electrolysis cells using a substrate without buffer solution.

    PubMed

    Song, Young-Hyun; Hidayat, Syarif; Kim, Han-Ki; Park, Joo-Yang

    2016-06-01

    The aim of this work was to use substrate without buffer solution in a microbial reverse-electrodialysis electrolysis cell (MREC) for hydrogen production under continuous flow condition (10 cell pairs of RED stacks, HRT=5, 7.5, and 15h). Decreasing in the HRT (increasing in the organic matter) made cell current stable and increased. Hydrogen gas was produced at a rate of 0.61m(3)-H2/m(3)-Van/d in H-MREC, with a COD removal efficiency of 81% (1.55g/L/d) and a Coulombic efficiency of 41%. This MREC system without buffer solution could successfully produce hydrogen gas at a consistent rate.

  17. The influence of potassium clavulanate on the rate of amoxicillin sodium degradation in phosphate and acetate buffers in the liquid state.

    PubMed

    Vahdat, Laleh; Sunderland, Bruce

    2009-04-01

    The stability of aqueous admixtures of amoxicillin sodium and potassium clavulanate was studied in the liquid state at selected pH values. Potassium clavulanate was found to catalyze the rate of degradation of amoxicillin sodium under the conditions of this study. In phosphate buffer (at pH 7.0) both amoxicillin sodium and potassium clavulanate showed first-order degradation when stored separately. However, when combined the rate of amoxicillin degradation increased and t(90) values for amoxicillin decreased from 69.6 min for amoxicillin alone to 10.8 min for amoxicillin in the combination at 55 degrees C. A kinetic model was developed that explained the catalytic behavior of potassium clavulanate and phosphate buffer. In acetate buffer the rate of degradation of amoxicillin sodium followed first-order kinetics, but the catalytic effect of clavulanate caused curvature in the rate plots at higher temperatures and clavulanate concentrations. This catalytic effect was less than that occurred in phosphate buffer (where the t(90) value of amoxicillin decreased from 137.3 min for amoxicillin alone to 52.5 min for amoxicillin in combination at 55 degrees C). First-order bi-exponential decay occurred with amoxicillin degradation, which explained this change in rate.

  18. Rheological and hydrodynamic properties of cellulose acetate/ionic liquid solutions.

    PubMed

    Rudaz, Cyrielle; Budtova, Tatiana

    2013-02-15

    Rheological properties of cellulose acetate/1-ethyl-3-methylimidazolium acetate (EMIMAc) solutions are studied using shear dynamic and steady state rheology in a large range of polymer concentrations (from 0.1 to 10 wt.%) and temperatures (from 0 °C to 80 °C). Master plots for storage and loss moduli and for dynamic viscosity were built and shift parameters determined. Cellulose acetate/EMIMAc behaves as a classical polymer solution and obeys Cox-Merz law. Cellulose acetate intrinsic viscosity [η] was determined as a function of temperature and compared with the literature data for cellulose acetates dissolved in other solvents and cellulose dissolved in EMIMAc. Cellulose acetate intrinsic viscosity turned out to be much less temperature sensitive than that of cellulose. Specific viscosity-C[η] master plot was built: the slopes in log-log scale are 1.2 and 3.1 in dilute and semi-dilute regions, respectively. The activation energy as a function of concentration follows a power-law dependence.

  19. Closed-form solutions of performability. [modeling of a degradable buffer/multiprocessor system

    NASA Technical Reports Server (NTRS)

    Meyer, J. F.

    1981-01-01

    Methods which yield closed form performability solutions for continuous valued variables are developed. The models are similar to those employed in performance modeling (i.e., Markovian queueing models) but are extended so as to account for variations in structure due to faults. In particular, the modeling of a degradable buffer/multiprocessor system is considered whose performance Y is the (normalized) average throughput rate realized during a bounded interval of time. To avoid known difficulties associated with exact transient solutions, an approximate decomposition of the model is employed permitting certain submodels to be solved in equilibrium. These solutions are then incorporated in a model with fewer transient states and by solving the latter, a closed form solution of the system's performability is obtained. In conclusion, some applications of this solution are discussed and illustrated, including an example of design optimization.

  20. Mafenide acetate solution dressings: an adjunct in burn wound care.

    PubMed

    Shuck, J M; Thorne, L W; Cooper, C G

    1975-07-01

    A continuation of the study of 5% aqueous Sulfamylon solution dressings in burned patients was analyzed in 150 consecutive cases. The rate of invasive infection and mortality was not excessive. Dressings were used as an adjunct to other topical chemotherapeutic agents as well as homo/heterograft skin in the overall burn care program. Sulfamylon soaks were shown to be effective for debridement, granulation tissue protection and preparation, and bacterial control. The dressings were comfortable when in place and the wounds appeared clean. Epithelialization was not hampered so that the dressings could be utilized in partial thickness wounds as well as for mesh autografts on extensive burn surfaces=

  1. Buffered lidocaine and bupivacaine mixture – the ideal local anesthetic solution?

    PubMed Central

    Best, Corliss A; Best, Alyssa A; Best, Timothy J; Hamilton, Danielle A

    2015-01-01

    The use of injectable local anesthetic solutions to facilitate pain-free surgery is an integral component of many procedures performed by the plastic surgeon. In many instances, a solution that has both rapid onset and prolonged duration of analgesia is optimal. A combination of lidocaine and bupivacaine, plain or with epinephrine, is readily available in most Canadian health care settings where such procedures are performed, and fulfills these criteria. However, commercially available solutions of both medications are acidic and cause a burning sensation on injection. Buffering to neutral pH with sodium bicarbonate is a practical method to mitigate the burning sensation, and has the added benefit of increasing the fraction of nonionized lipid soluble drug available. The authors report on the proportions of the three drugs to yield a neutral pH, and the results of an initial survey regarding the use of the combined solution with epinephrine in hand surgery. PMID:26090348

  2. Ultrafast relaxation of zinc protoporphyrin encapsulated within apomyoglobin in buffer solutions.

    PubMed

    Luo, Liyang; Chang, Chin-Hao; Chen, Yue-Ching; Wu, Tung-Kung; Diau, Eric Wei-Guang

    2007-07-05

    The relaxation dynamics of a zinc protoporphyrin (ZnPP) in THF, KPi buffer, and encapsulated within apomyoglobin (apoMb) was investigated in its excited state using femtosecond fluorescence up-conversion spectroscopy with S2 excitation (lambda(ex) = 430 nm). The S2 --> S1 internal conversion of ZnPP is ultrafast (tau < 100 fs), and the hot S1 ZnPP species are produced promptly after excitation. The relaxation dynamics of ZnPP in THF solution showed a dominant offset component (tau = 2.0 ns), but it disappeared completely when ZnPP formed aggregates in KPi buffer solution. When ZnPP was reconstituted into the heme pocket of apoMb to form a complex in KPi buffer solution, the fluorescence transients exhibited a biphasic decay feature with the signal approaching an asymptotic offset: at lambda(em) = 600 nm, the rapid component decayed in 710 fs and the slow one in 27 ps; at lambda(em) = 680 nm, the two time constants were 950 fs and 40 ps. We conclude that (1) the fast-decay component pertains to an efficient transfer of energy from the hot S1 ZnPP species to apoMb through a dative bond between zinc and proximal histidine of the protein; (2) the slow-decay component arises from the water-induced vibrational relaxation of the hot S1 ZnPP species; and (3) the offset component is due to S1 --> T1 intersystem crossing of the surviving cold S1 ZnPP species. The transfer of energy through bonds might lead the dative bond to break, which explains our observation of the degradation of ZnPP-Mb samples in UV-vis and CD spectra upon protracted excitation.

  3. A comparison of blood factor XII autoactivation in buffer, protein cocktail, serum, and plasma solutions.

    PubMed

    Golas, Avantika; Yeh, Chyi-Huey Josh; Pitakjakpipop, Harit; Siedlecki, Christopher A; Vogler, Erwin A

    2013-01-01

    Activation of blood plasma coagulation in vitro by contact with material surfaces is demonstrably dependent on plasma-volume-to-activator-surface-area ratio. The only plausible explanation consistent with current understanding of coagulation-cascade biochemistry is that procoagulant stimulus arising from the activation complex of the intrinsic pathway is dependent on activator surface area. And yet, it is herein shown that activation of the blood zymogen factor XII (Hageman factor, FXII) dissolved in buffer, protein cocktail, heat-denatured serum, and FXI deficient plasma does not exhibit activator surface-area dependence. Instead, a highly-variable burst of procoagulant-enzyme yield is measured that exhibits no measurable kinetics, sensitivity to mixing, or solution-temperature dependence. Thus, FXII activation in both buffer and protein-containing solutions does not exhibit characteristics of a biochemical reaction but rather appears to be a "mechanochemical" reaction induced by FXII molecule interactions with hydrophilic activator particles that do not formally adsorb blood proteins from solution. Results of this study strongly suggest that activator surface-area dependence observed in contact activation of plasma coagulation does not solely arise at the FXII activation step of the intrinsic pathway.

  4. Study on the oxidation form of adenine in phosphate buffer solution.

    PubMed

    Song, Yuan-Zhi; Zhou, Jian-Feng; Zhu, Feng-Xia; Ye, Yong; Xie, Ji-Min

    2010-07-01

    The oxidation of adenine in phosphate buffer solution is investigated using square-wave voltammetry and in situ UV spectroelectrochemistry. The geometry of adenine and the derivatives optimized at DFTB3LYP-6-31G (d, p)-PCM level is in agreement with the crystal structure, and the imitated UV spectra of adenine and the product at electrode are consistent with the in situ UV spectra. The relationship between the electrochemical property and the molecular structure is also discussed. The experimental and theoretical results show that the adenine oxidation origins from the neutral adenine.

  5. Simultaneous pollutant removal and electricity generation in denitrifying microbial fuel cell with boric acid-borate buffer solution.

    PubMed

    Chen, Gang; Zhang, Shaohui; Li, Meng; Wei, Yan

    2015-01-01

    A double-chamber denitrifying microbial fuel cell (MFC), using boric acid-borate buffer solution as an alternative to phosphate buffer solution, was set up to investigate the influence of buffer solution concentration, temperature and external resistance on electricity generation and pollutant removal efficiency. The result revealed that the denitrifying MFC with boric acid-borate buffer solution was successfully started up in 51 days, with a stable cell voltage of 205.1 ± 1.96 mV at an external resistance of 50 Ω. Higher concentration of buffer solution favored nitrogen removal and electricity generation. The maximum power density of 8.27 W/m(3) net cathodic chamber was obtained at a buffer solution concentration of 100 mmol/L. An increase in temperature benefitted electricity generation and nitrogen removal. A suitable temperature for this denitrifying MFC was suggested to be 25 °C. Decreasing the external resistance favored nitrogen removal and organic matter consumption by exoelectrogens.

  6. Regeneration of basic sorbents used in the recovery of acetic acid from dilute aqueous solution

    SciTech Connect

    Ng, M.; King, C.J.

    1988-10-01

    The regeneration of basic sorbents used in the recovery of dilute aqueous acetic acid was explored. The regeneration methods studied were solvent leaching and vaporization. The resins used were weak base anion exchange resins, Dow Chemical Company's Dowex MWA-1 (tertiary amine resin) and Celanese Corporation's Aurorez (polybenzimidazole resin). The equilibrium between the aqueous acetic acid solution and the resins was measured in batch experiments. The composite isotherms calculated from these data wee comparable to those of other researchers. Methanol was used as the solvent to leach acetic acid from the resin. The equilibrium data from the batch experiments were used in the local-equilibrium theory of fixed-bed devices to model the desorption behavior of acetic acid in methanol. Both sorption and desorption equilibrium data were used in chemical complexation models to obtain sorption affinities and capacities of the resin for acetic acid. However, the amount of methanol needed to achieve a high degree of regeneration was too large to be economical. 15 refs., 25 figs., 3 tabs.

  7. Poly(N-vinylimidazole) gels as insoluble buffers that neutralize acid solutions without dissolving.

    PubMed

    Horta, Arturo; Piérola, Inés F

    2009-04-02

    Typical buffers are solutions containing weak acids or bases. If these groups were anchored to insoluble gels, what would be their behavior? Simple thermodynamics is used to calculate the pH in two-phase systems that contain the weak acid or base fixed to only one of the phases and is absent in the other. The experimental reference of such systems are pH sensitive hydrogels and heterogeneous systems of biological interest. It is predicted that a basic hydrogel immersed in slightly acidic solutions should absorb the acid and leave the external solution exactly neutral (pH 7). This is in accordance with experimental results of cross-linked poly(N-vinylimidazole). The pH 7 cannot be obtained if the system were homogeneous; the confinement of the weak base inside the gel phase is a requisite for this neutral pH in the external solution. The solution inside the gel is regulated to a much higher pH, which has important implications in studies on chemical reactions and physical processes taking place inside a phase insoluble but in contact with a solution.

  8. 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.

  9. Adsorption of N-alkylpyridinium chlorides from water and salt solutions on cellulose acetate ultrafiltration membranes

    SciTech Connect

    Klimenko, N.A.; Yaroshenko, N.A.; Kondratova, T.B.

    1988-09-01

    A study has been made of the adsorption of three homologues in the N-alkylpyridinium chloride series from water and salt solutions, over a wide range of concentrations, on cellulose acetate ultrafiltration membranes, Grades UAM-500 and UAM-150. When adsorption takes place from true solutions, the membrane surface is hydrophobized. In the region of micellar solutions, nonassociated molecules and micelles are adsorbed in the mesopores and supermicropores, forming a mosaic adsorption layer. The thickness of the modifying layer depends on the length of the hydrophobic radical and on the composition of the system.

  10. Development anmd testing of electrophoresis solutions. Task I.1: Development of optimal buffer system

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Two buffers were explored for testing: low ionic strength electrophoresis buffer with and without density gradient material. It was found that the electrophoresis routine was better tolerated when Ficoll was present. The results of a viability study of primary human fetal kidney (HFK-1) cells at the first passage are shown. Cell strain HFK-1 was used in several experiments at the first and second passage. The HFK consisted mainly of fibroblasts, and HFK-1 has a high epithelioid cell content. The chromosomes of HFK were examined and found to be euploid. The stock medium for cell electrophoresis is described. In this solution density gradient solutes such as sucrose and Ficoll are dissolved to bring the osmolarity to 0.30. Its ionic strength is less than 0.01M, and its conductivity is usually 0.0011 mho/cm. Methods for viability determination included direct microscopic counting of the percent cells attached and spread within 24 hr of plating test cultures or electrophoretically separated fractions. The Cytograf viability assay concept was tested, and shown that blue stained cells scatter less light into the 0.8 to 3.3 deg angular interval than do unstained cells.

  11. Chelator-buffered nutrient solution is ineffective in extracting Ni from seeds of Alyssum.

    PubMed

    Centofanti, Tiziana; Tappero, Ryan V; Davis, Allen P; Chaney, Rufus L

    2011-01-01

    Hyperaccumulator species of the genera Alyssum can accumulate 100 times more Ni than normal crops and are therefore used for phytomining and phytoextraction of nickel contaminated soils. Basic studies on the physiology and metal uptake mechanisms of these plants are needed to increase efficiency and uptake capacity of Nickel (Ni) by hyperaccumulators. Recent attempts to disclose if those hyperaccumulator species require higher Ni level than normal plants failed because of the high Ni content in the seeds (7000-9000 microg g(-1)). In this study, we attempted to use chelator buffered nutrient solution to deplete Ni from the seed/seed coat and to obtain low Ni seedlings of Alyssum cultivars to be used in physiology studies. HEDTA-buffered nutrient solution did not deplete Ni from the seeds, perhaps because Ni was mainly localized within the seedling embryonic tissues with greatest Ni enrichment in the cotyledons and hypocotyls. We could not observe any positive correlation between seed fitness and germination capacity with seed Ni content. Investigation of nickel localization in Alyssum seeds using synchrotron X-ray microfluorescence (micro-SXRF) showed that nickel is localized in the embryonic tissues with greatest Ni enrichment observed in the cotyledons and hypocotyl.

  12. Calcium uptake and force development by skinned muscle fibres in EGTA buffered solutions

    PubMed Central

    Ford, L. E.; Podolsky, R. J.

    1972-01-01

    1. The uptake of 45Ca and the development of force by segments of skinned muscle fibres were measured in Ca solutions buffered with EGTA. When the Ca ion concentration in these solutions was above the contraction threshold, Ca was accumulated by the sarcoplasmic reticulum during the delay phase before force developed. The uptake rate increased, and the length of the delay decreased, when the concentration of the calcium buffer was increased. 2. The maximum accumulation of Ca was 2-3 mM. Force developed, ending the delay phase, when the calcium uptake approached this maximum level. 3. The pattern of force development suggested that this process was often accompanied by a sudden release of accumulated Ca. 4. The relation between the kinetics of 45Ca uptake and the interaction of calcium with EGTA and the sarcoplasmic reticulum is discussed. The data indicate that at the low concentrations necessary for relaxation the sarcoplasmic reticulum takes up Ca fast enough to account for the rate at which force falls when intact muscle fibres relax. PMID:5046147

  13. Photoluminescent distinction among plant life forms using phosphate buffered saline extract solutions.

    PubMed

    Danielson, Timothy L; Obeidat, Safwan; Rayson, Gary D; Anderson, Dean M; Fredrickson, Ed L; Estell, Rick E

    2006-07-01

    Photoluminescence of plant extract solutions has been investigated for discrimination of plant life forms (grasses, forbs, and shrubs) using principal component analysis (PCA). Clippings from each of six plant species representing three different plant life forms potentially found in the diets of free-ranging herbivores in the Chihuahuan Desert of North America were investigated for possible discernment. These plants included Sporobolus flexuosus (mesa dropseed, a grass), Pleuraphis mutica (tobosa, a grass), Dimorphocarpa wislizenii (spectacle pod, a forb), Sphaeralcea incana (pale globemallow, a forb), Flourensia cernua leaves (tarbush, a shrub), and Atriplex canescens leaves and stems (fourwing saltbush, a shrub). Emission spectra (370-600 nm) from phosphate buffered saline (PBS) extract solutions (pH 2.2, 7.5 and 12.5) were recorded for each plant with excitation at 365 nm. Use of PBS minimized chlorophyll interference. Discernment among plant life forms within these plant species was achieved.

  14. Performance of cellulose acetate butyrate membranes in hyperfiltration of sodium chloride and urea feed solution

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Leban, M.

    1973-01-01

    Cellulose acetate butyrate (CAB) membranes are shown to give high salt and urea rejection with water flux of about 3 gallons/sq ft per day at 600 psig. Membranes prepared from a formulation containing glyoxal show a significant increase in flux and decrease in salt and urea rejection with drying time. Zero drying time gives maximum urea and salt rejection and is therefore most suitable for hyperfiltration of sodium chloride and urea feed solution.

  15. Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors

    SciTech Connect

    Paranthaman, Mariappan Parans; Qiu, Xiaofeng; List III, Frederick Alyious; Zhang, Yifei; Li, Xiaoping; Sathyamurthy, Srivatsan; Thieme, C. L. H.; Rupich, M. W.

    2011-01-01

    Abstract The main objective of this research is to find a suitable alternate solution based seed layer for the standard RABiTS three-layer architecture of physical vapor deposited CeO cap/YSZ barrier/Y O seed on Ni-5%W metal tape. In the present work, we have identified CeO buffer layer as a potential replacement for Y O seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of CeO (pure and Zr, Cu and Gd-doped) directly on biaxially textured Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial CeO phase with slightly improved out-of-plane texture compared to the texture of the underlying Ni-W substrates can be achieved in pure, undoped CeO samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO seeds using sputtering. Both sputtered CeO cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO /Ni-5W substrates. High critical currents per unit width, of 264 A/cm (critical current density, of 3.3 MA/cm ) at 77 K and 0.01 T was achieved for 0.8 m thick MOD-YBCO films grown on MOD-CeO seeds. These results indicate that CeO films can be grown directly on Ni-5W substrates and still support high performance YBCO coated conductors. This work holds promise for a route for producing low-cost buffer architecture for RABiTS based YBCO coated conductors.

  16. Physical properties and biocompatibility of cellulose/soy protein isolate membranes coagulated from acetic aqueous solution.

    PubMed

    Luo, Li-Hua; Wang, Xiao-Mei; Zhang, Yu-Feg; Liu, Yong-Ming; Chang, Peter R; Wang, Yan; Chen, Yun

    2008-01-01

    A series of cellulose/soy protein isolate (SPI) membranes was prepared from cellulose and SPI solution by casting and coagulation from 5 wt% acetic acid and 5 wt% sulphuric acid aqueous solution, respectively. The structure and properties of the membranes were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and tensile testing. The effects of SPI content (W(SPI)) and the coagulants on the structure and properties of the membranes were investigated. The membranes exhibited porous structure. The pore size in the surfaces and cross-sections of the membranes increased with an increase of W(SPI) regardless of the coagulants. The membranes containing 10 wt% W(SPI) showed higher tensile strength and elongation at break than other membranes. The membranes with the same W(SPI) coagulated from acetic acid solution exhibited higher values of tensile strength, elongation at break and pore size in the surfaces and cross-sections than those corresponding membranes coagulated from sulphuric acid. The biocompatibility of the acetic acid-coagulated membranes was preliminarily evaluated by cell culture and in vivo implantation experiments. The results revealed that human umbilical vein endothelial cells (ECV304) grew well on this biomaterial. In comparison with the pure cellulose membrane, because of the incorporation of SPI and the resultant alteration of microstructure, the SPI-modified membranes showed an improved in vivo biocompatibility and biodegradability in the implantation experiments. These cellulose/SPI membranes warrant further explorations in biomedical fields.

  17. Characteristics of Zinc Phosphate Coating Activated by Different Concentrations of Nickel Acetate Solution

    NASA Astrophysics Data System (ADS)

    Abdalla, Khalid; Zuhailawati, H.; Rahmat, Azmi; Azizan, A.

    2017-02-01

    Activation pretreatment with nickel acetate solution at various concentrations was performed prior to the phosphating step to enhance the corrosion resistance of carbon steel substrates. The activation solution was studied over various concentrations: 10, 50, and 100 g/L. The effects of these concentrations on surface characteristics and microstructural evolution of the coated samples were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The electrochemical behavior was evaluated using potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion test in a 3.5 pct NaCl solution. Significant increases in the nucleation sites and surface coverage of zinc phosphate coating were observed as the concentration of activation solution reached 50 g/L. The electrochemical analysis revealed that the activation treatment with 50 g/L nickel acetate solution significantly improved the protection ability of the zinc phosphate coating. The corrosion current density of activated phosphate coating with 50 g/L was reduced by 64.64 and 13.22 pct, compared to the coatings obtained with activation solutions of 10 and 100 g/L, respectively.

  18. Critical zinc[sup +2] activities for sour orange determined with chelator-buffered nutrient solutions

    SciTech Connect

    Swietlik, D.; Zhang, L. )

    1994-07-01

    Chelator-buffered nutrient solutions were used to study the effect of different levels of Zn activity in the rhizosphere on growth and nutritive responses of various tissues of sour orange seedlings. The seedlings were grown for 3 months in a growth chamber in a hydroponic culture containing from 5 to 69 [mu]m and 5 to 101 [mu]m total Zn in Expts. 1 and 2, respectively. Zn[sup +2] activities were calculated with a computerized chemical equilibrium model, and buffered by inclusion of a chelator, diethylenetriamine pentaacetate (DTPA), at 74 and 44 [mu]m in excess of the sum of Fe, Mn, Zn, Cu, Ni, and Co in Expts. 1 and 2, respectively. The use of DTPA-buffered solutions proved successful in imposing varying degrees of Zn deficiency. The deficiency was confirmed by leaf symptomatology, leaf chemical analyses, i.e., <16 mg[center dot]kg[sup [minus]1] Zn, and responses to foliar sprays and application of Zn to the roots. Growth parameters varied in their sensitivity to Zn deficiency, i.e., root dry weight < leaf number and white root growth < stem dry weight < leaf dry weight < shoot elongation and leaf area. The critical activities, expressed as pZn = [minus]log(Zn[sup +2]), were [approximately]10.2 [+-] 0.2 for root dry weight, 10.1 [+-] 0.2 for leaf number and white root growth, 10.0 [+-] 0.2 for stem dry weight, 9.9 [+-] 0.2 for leaf dry weight, and 9.8 [+-] 0.2 for shoot growth and leaf area. Increases in growth were observed in response to Zn applications even in the absence of visible Zn-deficiency symptoms. Seedlings containing > 23 mg[center dot]kg[sup [minus]1] Zn in leaves did not respond to further additions of Zn to the nutrient solution. Zinc foliar sprays were less effective than Zn applications to the roots in alleviating severe Zn deficiency because foliar-absorbed Zn was not translocated from the top of the roots and thus could not correct Zn deficiency in the roots.

  19. Effect of phosphate buffer on photodegradation reactions of riboflavin in aqueous solution.

    PubMed

    Ahmad, Iqbal; Fasihullah, Q; Vaid, Faiyaz H M

    2005-03-01

    The effect of phosphate buffer on aerobic photodegradation reactions of riboflavin (RF) at pH 7.0 has been studied. The photoproducts of the two major reactions, viz., intramolecular photoreduction and intramolecular photoaddition, have been determined by a specific multicomponent spectrophotometric method. The overall photodegradation of riboflavin in the presence of phosphate buffer involves the participation of both H2PO4-and HPO4(2-) species. The second-order rate constants for the H2PO4(-)-catalysed photodegradation of riboflavin (normal photolysis) to lumichrome (LC) and HPO4(2-)-catalysed photodegradation of riboflavin (photoaddition) to cyclodehydroriboflavin (CDRF) are 0.93 x 10(-4) and 4.0 x 10(-4) M(-1) s(-1), respectively. The addition of 0.25-2.00 M phosphate to RF solutions at pH 7.0 gives rise to RF-HPO4(2-) complex and hence the quenching of 4-36% fluorescence, respectively. This results in the suppression of normal photolysis leading to the formation of LC in favour of photoaddition to yield CDRF. The present study shows the involvement of H2PO4- anions in the base-catalysed degradation of riboflavin by normal photolysis vis-a-vis the involvement of HPO42- anions in photoaddition reactions of riboflavin suggested earlier [M. Schuman Jorns, G. Schollnhammer, P. Hemmerich, Intramolecular addition of the riboflavin side chain. Anion-catalysed neutral photochemistry, Eur. J. Biochem. 57 (1975) 35-48].

  20. 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)

  1. Photodegradation of Mercaptopropionic Acid- and Thioglycollic Acid-Capped CdTe Quantum Dots in Buffer Solutions.

    PubMed

    Miao, Yanping; Yang, Ping; Zhao, Jie; Du, Yingying; He, Haiyan; Liu, Yunshi

    2015-06-01

    CdTe quantum dots (QDs) were synthesized by 3-mercaptopropionic acid (MPA) and thioglycollic acid (TGA) as capping agents. It is confirmed that TGA and MPA molecules were attached on the surface of the QDs using Fourier transform infrared (FT-IR) spectra. The movement of the QDs in agarose gel electrophoresis indicated that MPA-capped CdTe QDs had small hydrodynamic diameter. The photoluminescence (PL) intensity of TGA-capped QDs is higher than that of MPA-capped QDs at same QD concentration because of the surface passivation of TGA. To systemically investigate the photodegradation, CdTe QDs with various PL peak wavelengths were dispersed in phosphate buffered saline (PBS) and Tris-borate-ethylenediaminetetraacetic acid (TBE) buffer solutions. It was found that the PL intensity of the QDs in PBS decreased with time. The PL peak wavelengths of the QDs in PBS solutions remained unchanged. As for TGA-capped CdTe QDs, the results of PL peak wavelengths in TBE buffer solutions indicated that S(2-) released by TGA attached to Cd(2+) and formed CdS-like clusters layer on the surface of aqueous CdTe QDs. In addition, the number of TGA on the CdTe QDs surface was more than that of MPA. When the QDs were added to buffer solutions, agents were removed from the surface of CdTe QDs, which decreased the passivation of agents thus resulted in photodegradation of CdTe QDs in buffer solutions.

  2. Covalent binding of biological samples to solid supports for scanning probe microscopy in buffer solution.

    PubMed Central

    Karrasch, S; Dolder, M; Schabert, F; Ramsden, J; Engel, A

    1993-01-01

    Scanning force microscopy allows imaging of biological molecules in their native state in buffer solution. To this end samples have to be fixed to a flat solid support so that they cannot be displaced by the scanning tip. Here we describe a method to achieve the covalent binding of biological samples to glass surfaces. Coverslips were chemically modified with the photoactivatable cross-linker N-5-azido-2-nitrobenzoyloxysuccinimide. Samples are squeezed between derivatized coverslips and then cross-linked to the glass surface by irradiation with ultraviolet light. Such samples can be imaged repeatedly by the scanning force microscope without loss of image quality, whereas identical but not immobilized samples are pushed away by the stylus. Images FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 PMID:8312482

  3. Kinetics and hydrolysis of fenamiphos, fipronil, and trifluralin in aqueous buffer solutions.

    PubMed

    Ramesh, A; Balasubramanian, M

    1999-08-01

    Hydrolyses of fenamiphos, fipronil, and trifluralin were studied in aqueous buffer solutions of pH 4.1, 7.1, and 9.1 at different temperatures, 5, 22 +/- 1, 32 +/- 1, and 50 +/- 1 degrees C. Fenamiphos, fipronil, and trifluralin were found to be more stable in acidic and neutral buffer solutions at temperatures of 5 and 22 +/- 1, and dissipation is rapid at 50 +/- 1 degrees C. In basic buffer and at higher temperature, degradation of fenamiphos was found to be very rapid when compared with fipronil and trifluralin. The rate constants calculated at 32 degrees C for fenamiphos were 2349.4 x 10(-)(8) (pH 4.1), 225.2 x 10(-)(8) (pH 7.1), and 30476.0 x 10(-)(8) (pH 9.1); for fipronil 1750.0 x 10(-)(8) (pH 4.1), 3103.0 x 10(-)(8) (pH 7.1), and 3883.0 x 10(-)(8) (pH 9.1); and for trifluralin 2331.0 x 10(-)(8) (pH 4.1), 2360.0 x 10(-)(8) (pH 7.1), and 3188.0 x 10(-)(8) (pH 9.1). On the basis of rate constant values, these pesticides appeared to be more susceptible to hydrolysis than synthetic organophosphorus compounds such as chlorpyriphos, diazinon, malathion, and ronnel. DT(50) values calculated at 32 degrees C were 228 (pH 4.1), 5310.24 (pH 7.1), and 37.68 (pH 9.1) h for fenamiphos; 608.6 (pH 4.1), 373.9 (pH 7.1), and 270.2 (pH 9.1) h for fipronil; and 502.1 (pH 4.1), 496.8 (pH 7.1), and 355.7 (pH 9.1) h for trifluralin.

  4. Sulfate influx on band 3 protein of equine erythrocyte membrane (Equus caballus) using different experimental temperatures and buffer solutions.

    PubMed

    Casella, S; Piccione, D; Ielati, S; Bocchino, E G; Piccione, G

    2013-06-01

    The aim of this study was to assess the anion transport in equine erythrocytes through the measurement of the sulfate uptake operating from band 3 using different experimental temperatures and buffer solutions. Blood samples of six clinically healthy horses were collected via jugular vein puncture, and an emochrome-citometric examination was performed. The blood was divided into four aliquots and by centrifugation and aspiration the plasma and buffy coat were carefully discarded. The red blood cells were washed with an isosmotic medium and centrifuged. The obtained cell suspensions were incubated with two different experimental buffer solutions (buffer A: 115 mM Na2SO4, 10 mM NaCl, 20 mM ethylenediaminetetraacetic acid, 30 mM glucose; and buffer B: 115 mM Na2SO4, 10 mM NaCl, 20 mM ethylenediaminetetraacetic acid, 30 mM MgCl2) in a water bath for 1 h at 25 °C and 37 °C. Normal erythrocytes, suspended at 3% hematocrit, were used to measure the SO4= influx by absorption spectrophotometry at 425 nm wavelength. Unpaired Student's t-test showed a statistically significant decrease (P < 0.01) of rate constants in equine erythrocytes at 25 °C versus 37 °C using both experimental buffer solutions. Comparing the buffer A with buffer B unpaired Student's t-test showed statistically lower values (P < 0.0001) for A solution versus B solution both at 25 °C and at 37 °C. The greater inhibition of SO4 (=) influx measured in equine erythrocytes indicates the increased formation of the sulfydryl bonds in band 3 and the modulation of the sulfydryl groups, culminating in the conformational changes in band 3.

  5. Relationship between Virucidal Efficacy and Free Iodine Concentration of Povidone-Iodine in Buffer Solution.

    PubMed

    Wada, Hideki; Nojima, Yasuhiro; Ogawa, Satoko; Hayashi, Nobuyuki; Sugiyama, Noriyoshi; Kajiura, Takumi; Ueda, Tomofumi; Morimoto, Shota; Yokota, Katuhiro

    2016-01-01

    Povidone-iodine solutions prepared to various concentrations (0.01, 0.1, 1 and 10%) with 0.2M phosphate buffer (pH 7.0) (PVP-I PB) were analyzed to determine their free iodine concentrations using membrane permeation cells, and their inactivation effects on three viruses (influenza A virus, poliovirus type 1 and adenovirus type 3) were examined. The free iodine concentrations in the 0.01-10% PVP-I PB were determined to be 1.84, 4.88, 1.58 and 0.17 ppm (approximate values), respectively, with the maximum obtained for the 0.1% solution. The virucidal efficacy of these PVP-I PB against poliovirus type 1 and adenovirus type 3 was found to be generally dependent on free iodine concentration, with the 0.1% solution being the most effective. Influenza A virus was inactivated with an action time of 15 s at all four concentrations examined. The results of this study suggested an association between free iodine concentration and virucidal efficacy for the 0.01-10% PVP-I PB.

  6. Membrane transport of hydrocortisone acetate from supersaturated solutions; the role of polymers.

    PubMed

    Raghavan, S L; Kiepfer, B; Davis, A F; Kazarian, S G; Hadgraft, J

    2001-06-19

    Permeation of hydrocortisone acetate (HA) from supersaturated solutions was studied across a model silicone membrane. Supersaturated solutions were prepared using the cosolvent technique with propylene glycol and water (or aqueous polymer solutions) as the cosolvents. In the absence of the polymer, the flux of HA was similar at all degrees of saturation and was not significantly different from the value obtained for a saturated solution. Flux enhancement, as a result of supersaturation, was observed with all the polymers. The flux increased with increasing polymer concentration, reached a maximum and decreased at higher polymer percentages. The amount of polymer required for maximum enhancement differed for each polymer. The decrease of flux at high polymer concentrations is attributed to changes in microviscosity and a marginal increase in solubility. The infrared spectroscopic and differential scanning calorimetry data suggest that HA-polymer interactions occurred through hydrogen bonding thus explaining the proposed mechanism of the anti-nucleant properties of the polymers.

  7. Radiolysis of aqueous solutions of acetic acid in the presence of Na-montmorillonite

    NASA Technical Reports Server (NTRS)

    Navarro-Gonzalez, R.; Negron-Mendoza, A.; Ramos, S.; Ponnamperuma, C.

    1990-01-01

    The gamma-irradiation of 0.8 mol dm-3 aqueous, oxygen-free acetic acid solutions was investigated in the presence or absence of Na-montmorillonite. H2, CH4, CO, CO2, and several polycarboxylic acids were formed in all systems. The primary characteristics observed in the latter system were: (1) Higher yield of the decomposition of acetic acid; (2) Lower yield of the formation of polycarboxylic acids; (3) No effect on the formation of methane; (4) Higher yield of the formation of carbon dioxide; and (5) The reduction of Fe3+ in the octahedral sites of Na-montmorillonite. A possible reaction scheme was proposed to account for the observed changes. The results are important in understanding heterogeneous processes in radiation catalysis and might be significant to prebiotic chemistry.

  8. The Acid Hydrolysis Mechanism of Acetals Catalyzed by a Supramolecular Assembly in Basic Solution

    SciTech Connect

    Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

    2008-09-24

    A self-assembled supramolecular host catalyzes the hydrolysis of acetals in basic aqueous solution. The mechanism of hydrolysis is consistent with the Michaelis-Menten kinetic model. Further investigation of the rate limiting step of the reaction revealed a negative entropy of activation ({Delta}S{double_dagger} = -9 cal mol{sup -1}K{sup -1}) and an inverse solvent isotope effect (k(H{sub 2}O)/k(D{sub 2}O) = 0.62). These data suggest that the mechanism of hydrolysis that takes place inside the assembly proceeds through an A-2 mechanism, in contrast to the A-1 mechanism operating in the uncatalyzed reaction. Comparison of the rates of acetal hydrolysis in the assembly with the rate of the reaction of unencapsulated substrates reveals rate accelerations of up to 980 over the background reaction for the substrate diethoxymethane.

  9. Efficient quantum dot light-emitting diodes with solution-processable molybdenum oxide as the anode buffer layer

    NASA Astrophysics Data System (ADS)

    He, Shaojian; Li, Shusheng; Wang, Fuzhi; Wang, Andrew Y.; Lin, Jun; Tan, Zhan'ao

    2013-05-01

    Quantum dot light-emitting diodes (QD-LEDs) are characterized by pure and saturated emission colors with narrow bandwidth. Optimization of the device interface is an effective way to achieve stable and high-performance QD-LEDs. Here we utilized solution-processed molybdenum oxide (MoOx) as the anode buffer layer on ITO to build efficient QD-LEDs. Using MoOx as the anode buffer layer provides the QD-LED with good Ohmic contact and a small charge transfer resistance. The device luminance is nearly independent of the thickness of the MoOx anode buffer layer. The QD-LEDs with a MoOx anode buffer layer exhibit a maximum luminance and luminous efficiency of 5230 cd m-2 and 0.67 cd A-1 for the yellow emission at 580 nm, and 7842 cd m-2 and 1.49 cd A-1 for the red emission at 610 nm, respectively.

  10. BIOKID: Randomized controlled trial comparing bicarbonate and lactate buffer in biocompatible peritoneal dialysis solutions in children [ISRCTN81137991

    PubMed Central

    Nau, Barbara; Schmitt, Claus P; Almeida, Margarida; Arbeiter, Klaus; Ardissino, Gianluigi; Bonzel, Klaus E; Edefonti, Alberto; Fischbach, Michel; Haluany, Karin; Misselwitz, Joachim; Kemper, Markus J; Rönnholm, Kai; Wygoda, Simone; Schaefer, Franz

    2004-01-01

    Background Peritoneal dialysis (PD) is the preferred dialysis modality in children. Its major drawback is the limited technique survival due to infections and progressive ultrafiltration failure. Conventional PD solutions exert marked acute and chronic toxicity to local tissues. Prolonged exposure is associated with severe histopathological alterations including vasculopathy, neoangiogenesis, submesothelial fibrosis and a gradual loss of the mesothelial cell layer. Recently, more biocompatible PD solutions containing reduced amounts of toxic glucose degradation products (GDPs) and buffered at neutral pH have been introduced into clinical practice. These solutions contain lactate, bicarbonate or a combination of both as buffer substance. Increasing evidence from clinical trials in adults and children suggests that the new PD fluids may allow for better long-term preservation of peritoneal morphology and function. However, the relative importance of the buffer in neutral-pH, low-GDP fluids is still unclear. In vitro, lactate is cytotoxic and vasoactive at the concentrations used in PD fluids. The BIOKID trial is designed to clarify the clinical significance of the buffer choice in biocompatible PD fluids. Methods/design The objective of the study is to test the hypothesis that bicarbonate based PD solutions may allow for a better preservation of peritoneal transport characteristics in children than solutions containing lactate buffer. Secondary objectives are to assess any impact of the buffer system on acid-base status, peritoneal tissue integrity and the incidence and severity of peritonitis. After a run-in period of 2 months during which a targeted cohort of 60 patients is treated with a conventional, lactate buffered, acidic, GDP containing PD fluid, patients will be stratified according to residual renal function and type of phosphate binding medication and randomized to receive either the lactate-containing Balance solution or the bicarbonate-buffered Bicavera

  11. Effects of a phosphate buffered extracellular (Ep4) solution in preservation and reperfusion injury in the canine liver.

    PubMed

    Kawashima, Y; Ohwada, S; Sakata, K; Ohya, T; Tomizawa, N; Takeyoshi, I; Morishita, Y

    1999-02-01

    The Ep4 solution, a phosphate buffered extracellular-type solution, is effective in canine lung transplantation following a 96-hour hypothermic (4 degrees C) preservation. In this experiment, we used this solution for liver preservation followed by transplantation. We compared the Ep4 solution with the lactated Ringer's (LR) and the Collins' M (CM) solution (a phosphate buffered intracellular-type solution) in two studies, 1) 48-hour liver preservation, and 2) orthotopic liver transplantation after 5-hour preservation. In the preservation study, purine nucleoside phosphorylase (PNP) levels as a marker of endothelial damage, and alanine aminotransferase (ALT) levels were significantly lower in the livers immersed into the Ep4 solution than in those immersed into other solutions at 36 and 48 hours after preservation. Microscopically, the endothelial injury occurred 24 hours after preservation in the CM solution, and 36 hours after preservation in the LR and Ep4 solutions. In the transplantation study, serum PNP and ALT levels in the livers immersed in Ep4 solution showed a lower tendency compared with those in other solutions at the time of reperfusion, but the histological differences among three groups were not apparent. The present study suggests that the liver can be stored better for a longer time using Ep4 solution than using LR and CM solutions.

  12. Surface modifications of bioglass immersed in TRIS-buffered solution. A multitechnical spectroscopic study.

    PubMed

    Cerruti, Marta; Bianchi, Claudia L; Bonino, Francesca; Damin, Alessandro; Perardi, Alessandra; Morterra, Claudio

    2005-08-04

    Bioglass 45S5 is used in the medical field as a bone regenerative material. In fact, when immersed in body fluid, a layer of hydroxy carbonate apatite (HCA), an analogue to the mineral phase that bones are made of, is deposited on its surface. A mechanism that would explain this process has been hypothesized and includes cation leaching from the glass to the solution and formation of both a silica-rich layer and a Ca/P-rich surface layer, prior to the actual crystallization of HCA. The present paper analyzes the dissolution of 2-mum-size particles of Bioglass in TRIS-buffered solution, focusing on the modifications occurring at the surface of the particles. Results from Transmission FT-IR, Raman, and X-ray Photoelectron Spectroscopy were compared in order to obtain this information. In all cases, precise spectral band assignments were obtained by comparing Bioglass spectra, before and after reaction, with the spectra registered on some selected reference samples. The results confirm the hypothesized mechanism of Bioglass reactivity and yield new insights on the surface modifications of the samples. In particular, the following is shown: the strength of the surface H-bonding system and of water coordination decreases during the reaction; surface carbonates, initially mainly bound to Na, are substituted by an increasing amount of Ca-bound carbonates; and the final calcium phosphate layer obtained is very similar, but not identical, to carbonated hydroxyapatite.

  13. Transformation of nacre coatings into apatite coatings in phosphate buffer solution at low temperature.

    PubMed

    Guo, Yaping; Zhou, Yu

    2008-08-01

    Nacre coatings were deposited on Ti6Al4V substrates by electrophoretic technique, and subsequently converted into apatite coatings with hierarchical porous structures by treatment with a phosphate buffer solution. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma optical emission spectroscopy, X-ray photoelectron spectroscopy (XPS), and N(2) adsorption-desorption isotherms. The results show that the nacre coatings are converted into the plate-like apatite coatings via a dissolution-precipitation reaction, while the organic components of the nacre are reserved. The mesopores with pore size of 4.4 nm are formed within the plate-like structure, and the macropores are formed among the plate-like structure. Simulated body fluid (SBF) immersion tests reveal that the apatite coatings have a good in vitro bioactivity. Bone-like apatite crystals are formed on the surfaces of the apatite coatings after soaking in SBF for 12 h, and fill up the macropores on the coatings with increasing the soaking time. In addition, XPS indicates that a TiO(x) layer and PO(4) (3-) ions appear on the substrate surfaces by pretreatment with a H(3)PO(4)/HF solution. The TiO(x) layer and PO(4) (3-) ions can induce the formation of apatite crystals, resulting in a composition gradient from the oxide layer to the external apatite layer.

  14. Solubility of sulfur dioxide in aqueous solutions of acetic acid, sodium acetate, and ammonium acetate in the temperature range from 313 to 393 K at pressures up to 3.3 MPa: Experimental results and comparison with correlations/predictions

    SciTech Connect

    Xia, J.; Rumpf, B.; Maurer, G.

    1999-03-01

    In many chemical plants, for example in coal gasification processes or desulfurization equipment, sour gas absorption columns and sour water strippers are used to remove weak electrolyte gases like sulfur dioxide, hydrogen cyanide, hydrogen sulfide or carbon dioxide from aqueous solutions. The basic design of such equipment requires physico-chemical models to describe the phase equilibrium as well as the caloric properties of such mixtures. New experimental results for the solubility of sulfur dioxide in aqueous solutions of single solutes acetic acid, sodium acetate and ammonium acetate at temperatures from 313 to 393 K and total pressures up to 3.3 MPa are reported. Similar to the system sulfur dioxide-water, also in such systems with acetic acid and sodium or ammonium acetate a second (sulfur dioxide rich) liquid phase is observed at high sulfur dioxide concentrations. A model to describe the phase equilibrium is presented and calculated (i.e., predicted as well as correlated) phase equilibria are compared to the new experimental data.

  15. Methyltrimethoxysilane-insulated piezoelectric microcantilevers for direct, all-electrical biodetection in buffered aqueous solutions

    NASA Astrophysics Data System (ADS)

    Capobianco, Joseph A.; Shih, Wan Y.; Shih, Wei-Heng

    2006-12-01

    We have examined coating (PbMg1/3Nb2/3O3)0.63-(PbTiO3)0.37 (PMN-PT)/tin piezoelectric microcantilever sensors (PEMSs) with a thin methyltrimethoxysilane (MTMS) by a simple solution method to electrically insulate the PEMS for biodetection in phosphate buffered saline (PBS) solutions. The PMN-PT/tin PEMSs were constructed using PMN-PT freestanding films that exhibited an electric-field-enhanced giant piezoelectric coefficient. The insulation procedure involved spin coatings of MTMS followed by cross-linking in water, which yielded a coating layer of about 10nm in thickness on the tin side of the PEMS. We showed that the MTMS-insulated PMN-PT/tin PEMSs were capable of electrical self-excitation and self-sensing with a stable resonance spectrum exhibiting a quality factor of Q =50 when submerged in 0.1M PBS solution. Direct, all-electrical, in situ detection of Escherichia coli O157:H7 at various concentrations was demonstrated at a flow rate of 0.5ml/min. A MTMS-insulated PMN-PT/tin PEMS 725μm long consisting of a 22-μm-thick PMN-PT layer and a 6-μm-thick tin layer exhibited a mass detection sensitivity Δm /Δf=-3±2×10-12g/Hz and a concentration sensitivity of better than 100cells/ml in less than 1ml of liquid.

  16. 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.

  17. Substituent Effects on the Photodeprotection Reactions of Selected Ketoprofen Derivatives in Phosphate Buffered Aqueous Solutions.

    PubMed

    Liu, Mingyue; Li, Ming-De; Huang, Jinqing; Li, Tianlu; Liu, Han; Li, Xuechen; Phillips, David Lee

    2016-02-22

    Photodeprotection is an important reaction that has been attracting broad interest for use in a variety of applications. Recent advances in ultrafast and vibrational time-resolved spectroscopies can facilitate obtaining data to help unravel the reaction mechanisms involving in the photochemical reactions of interest. The kinetics and reaction mechanisms for the photodeprotection reactions of ketoprofen derivatives containing three different substituents (ibuprofen, Br and I) were investigated by femtosecond transient absorption (fs-TA) and nanosecond time-resolved resonance Raman (ns-TR(3)) spectroscopy methods in phosphate buffered solutions (PBS). Fs-TA allows us to detect the decay kinetics of the triplet species as the key precursor for formation of a carbanion species for three different substituents attached to ketoprofen. To characterize the structural and electronic properties of the corresponding carbanion and triplet intermediates, TR(3) spectroscopic experiments were conducted. The transient spectroscopy work reveals that the different substituents affect the photodecarboxylation reaction to produce carbon dioxide which in turn influences the generation of the carbanion species which determines the rate of the photorelease of the functional groups attached on the ketoprofen parent molecule. The fingerprint TR(3) spectroscopy results suggest that ketoprofen derivatives may be deactivated to produce a triplet carbanion when increasing the atom mass of the halogen atoms.

  18. Substituent Effects on the Photodeprotection Reactions of Selected Ketoprofen Derivatives in Phosphate Buffered Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Liu, Mingyue; Li, Ming-De; Huang, Jinqing; Li, Tianlu; Liu, Han; Li, Xuechen; Phillips, David Lee

    2016-02-01

    Photodeprotection is an important reaction that has been attracting broad interest for use in a variety of applications. Recent advances in ultrafast and vibrational time-resolved spectroscopies can facilitate obtaining data to help unravel the reaction mechanisms involving in the photochemical reactions of interest. The kinetics and reaction mechanisms for the photodeprotection reactions of ketoprofen derivatives containing three different substituents (ibuprofen, Br and I) were investigated by femtosecond transient absorption (fs-TA) and nanosecond time-resolved resonance Raman (ns-TR3) spectroscopy methods in phosphate buffered solutions (PBS). Fs-TA allows us to detect the decay kinetics of the triplet species as the key precursor for formation of a carbanion species for three different substituents attached to ketoprofen. To characterize the structural and electronic properties of the corresponding carbanion and triplet intermediates, TR3 spectroscopic experiments were conducted. The transient spectroscopy work reveals that the different substituents affect the photodecarboxylation reaction to produce carbon dioxide which in turn influences the generation of the carbanion species which determines the rate of the photorelease of the functional groups attached on the ketoprofen parent molecule. The fingerprint TR3 spectroscopy results suggest that ketoprofen derivatives may be deactivated to produce a triplet carbanion when increasing the atom mass of the halogen atoms.

  19. Monolayer formation of luminescent germanium nanoparticles on silica surface in aqueous buffer solution.

    PubMed

    Shirahata, Naoto

    2014-03-01

    The present paper reports monolayer formation of germanium nanoparticles (Ge NPs) on silica substrate. The NPs were prepared by hydride reduction of GeCl4, which is encapsulated with an inverse micelle of dimethyldioctylammonium bromide, with lithium aluminum hydride, and subsequent hydrogermylation of allylamine in the presence of platinum catalyst. The resultant NPs showed the blue photoluminescence property. Due to the terminal amine, the NPs were soluble highly in aqueous buffer solution. To fabricate a monolayer of Ge NPs, the chemical reactivity of the NPs was studied using a multi-functional microarray in which different kinds of siloxane monolayers were periodically aligned on a silica substrate. We observed using fluorescence microscope whether the terminal amines of the NPs recognize the specific monolayers in the microarray. In terms of fluorescence observation, the entire surface of the monolayer-covered microsize-domains emits uniformly the blue light. This suggests a high degree of coverage of the luminescent NPs covering over the monolayer regions in the microarray, and implies the non-occurrence of quenching through energy transfer between adjacent NPs.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  1. 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

  2. Anglesite (PbSO 4) solubility in acetate solutions: The determination of stability constants for lead acetate complexes to 85°C

    NASA Astrophysics Data System (ADS)

    Giordano, Thomas H.

    1989-02-01

    Anglesite solubilities were determined at 25, 40, 55, 70, and 85°C in solutions with equal molal concentrations of acetic acid and sodium acetate (each ranging from 0.001 to 0.25 m) and at pH values near 4.6. Experiments were conducted using 1000 ml, externally heated glass reaction vessels, and lead concentrations were measured using atomic absorption spectrophotometry. For run conditions with free acetate concentrations less than about 0.01 m, measured a anglesite solubilities are less than or equal to 100 mg/l. Above free acetate concentrations of 0.01 m, measured anglesite solubilities rise sharply to concentrations near 1000 mg/l. Extracted from these solubility data, by a numerical successive linear extrapolation method, were stoichiometries and thermodynamic stability constants (ionic strength = 0) for the complexes Pb(CH 3COO) + and Pb(CH 3COO) 2. Log K1 and log K2 values for the formation reactions Pb + + CH 3COO - = PbCH 3COO + and Pb 2+ + 2CH 3COO - = Pb(CH 3COO) 2 respectively are log K1: (2.4±0.1, 25°C), (2.4±0.1, 40°C), (2.5±0.1, 55°C), (2.6±0.1, 70°C), (2.7±0.2, 85°C) and log K2: (3.4±0.4, 25°C), (3.6±0.2, 40°C), (3.8 ±0.2, 55°C), (4.0±0.2, 70°C), (4.3±0.2, 85°C). Lead hydrolysis was found to be significant in those experiments conducted at 70 and 85°C. However, hydrolyzed lead was not detected at 25, 40, and 55°C. PbOH + as percent of total observed lead ranged from 0.2 to 24% and 2 to 86% in those experiments at 70 and 85°C, respectively. Calculations of lead speciation in acetate solutions show that the equivalence point for PbCH 3COO + and Pb(CH 3COO) 2 shifts to lower acetate concentrations from 25 to 85°C. These speciation calculations also suggest that lead acetate complexes could be significant in high acetate formation waters. These waters typically contain at least 1,000 ppm acetate (0.017 molal as acetic acid). Furthermore, if these waters are not too acid and if concentrations of competing ligands are low, lead

  3. Interactions of two amphiphilic penicillins with myoglobin in aqueous buffered solutions: a thermodynamic and spectroscopy study.

    PubMed

    Taboada, Pablo; Fernández, Yolanda; Mosquera, Víctor

    2004-01-01

    The interactions and complexation process of the amphiphilic penicillins sodium cloxacillin and sodium dicloxacillin with horse myoglobin in aqueous buffered solutions of pH 4.5 and 7.4 have been examined by equilibrium dialysis, zeta-potential, isothermal titration calorimetry (ITC) and UV-Vis absorbance techniques. A more opened structure of the protein molecules is detected as a consequence of the reduction of pH from 7.4 to 4.5. Binding isotherms and derived Hill coefficients reflect a cooperative binding behavior. Gibbs energies of binding per mole of drug were obtained from equilibrium dialysis data and compared with those derived from the zeta potential taking into account cooperativity. DeltaGads degrees values so obtained are large and negative at low concentrations where binding to the "high-energy" sites occurs and decreases with the drug concentration. The enthalpies of binding have been obtained from ITC and are small and exothermic so that the Gibbs energies of binding are dominated by large increases in entropy consistent with hydrophobic interactions. Other thermodynamic quantities of the binding mechanism, that is, entropy, DeltaSITCi, Gibbs energy, DeltaGITCi, the binding constant, KITCi, and the number of binding sites, ni, were also obtained, confirming the above results. From ITC data and following a theoretical model, the number of bound and free penicillin molecules was calculated, being higher at pH 4.5 than at pH 7.4. The binding of penicillin causes a conformational transition on protein structure as a consequence of the resulting intramolecular repulsion between the penicillin molecules bound to the protein. Thermodynamic quantites (the Gibbs energy of the transition in water, DeltaGw degrees , and in a hydrophobic environment, DeltaGhc degrees) of the denaturation process were calculated, indicating that at pH 4.5 some of the histidine residues are protonated, becoming accessible to solvent and giving rise to a more opened protein

  4. The stability of DLC film on nitrided CoCrMo alloy in phosphate buffer solution

    NASA Astrophysics Data System (ADS)

    Zhang, T. F.; Liu, B.; Wu, B. J.; Liu, J.; Sun, H.; Leng, Y. X.; Huang, N.

    2014-07-01

    CoCrMo alloy is often used as the material for metal artificial joint, but metal debris and metal ions are the main concern on tissue inflammation or tissue proliferation for metal prosthesis. In this paper, nitrogen ion implantation and diamond like carbon (DLC) film composite treatment was used to reduce the wear and ion release of biomedical CoCrMo substrate. The mechanical properties and stability of N-implanted/DLC composite layer in phosphate buffer solution (PBS) was evaluated to explore the full potential of N-implanted/DLC composite layer as an artificial joint surface modification material. The results showed that the DLC film on N implanted CoCrMo (N-implanted/DLC composite layer) had the higher surface hardness and wear resistance than the DLC film on virgin CoCrMo alloy, which was resulted from the strengthen effect of the N implanted layer on CoCrMo alloy. After 30 days immersion in PBS, the structure of DLC film on virgin CoCrMo or on N implanted CoCrMo had no visible change. But the adhesion and corrosion resistance of DLC on N implanted CoCrMo (N-implanted/DLC composite layer) was weakened due to the dissolution of the N implanted layer after 30 days immersion in PBS. The adhesion reduction of N-implanted/DLC composite layer was adverse for in vivo application in long term. So researcher should be cautious to use N implanted layer as an inter-layer for increasing CoCrMo alloy load carrying capacity in vivo environment.

  5. Evidence that intrinsic iron but not intrinsic copper determines S-nitrosocysteine decomposition in buffer solution.

    PubMed

    Vanin, Anatoly F; Muller, Bernard; Alencar, Jacicarlos L; Lobysheva, Irina I; Nepveu, Françoise; Stoclet, Jean-Claude

    2002-11-01

    The present experiments were designed to analyze the influence of copper and iron ions on the process of decomposition of S-nitrosocysteine (cysNO), the most labile species among S-nitrosothiols (RSNO). CysNO fate in buffer solution was evaluated by optical and electron paramagnetic resonance (EPR) spectroscopy, and the consequences on its vasorelaxant effect were studied on noradrenaline-precontracted rat aortic rings. The main results are the following: (i) copper or iron ions, especially in the presence of the reducing agent ascorbate, accelerated the decomposition of cysNO and markedly attenuated the amplitude and duration of the relaxant effect of cysNO; (ii) by contrast, the iron and copper chelators bathophenantroline disulfonic acid (BPDS) and bathocuproine disulfonic acid (BCS) exerted a stabilizing effect on cysNO, prolonged its vasorelaxant effect, and abolished the influence of ascorbate; (iii) in the presence of ascorbate, BPDS displayed a selective inhibitory effect toward the influence of iron ions (but not toward copper ions) on cysNO decomposition and vasorelaxant effect, while BCS prevented the effects of both copper and iron ions; (iv) L-cysteine enhanced stability and prolonged the relaxant effect of cysNO; (v) the process of iron-induced decomposition of cysNO was associated with the formation of EPR-detectable dinitrosyl-iron complexes (DNIC) either with non-thiol- or thiol-containing ligands (depending on the presence of L-cysteine), both of which exhibiting vasorelaxant properties. From these data, it is concluded that the amount of intrinsic copper was probably too low to produce a destabilizing effect even on the most labile RSNO, cysNO, and that only intrinsic iron, through the formation of DNIC, was responsible for the process of cysNO decomposition and thus influenced its vasorelaxant properties.

  6. Primary Action of Indole-3-acetic Acid in Crown Gall Tumors: Increase of Solute Uptake.

    PubMed

    Rausch, T; Kahl, G; Hilgenberg, W

    1984-06-01

    Exogenously added indole-3-acetic acid at a concentration of 100 micromolars stimulates d-glucose uptake (or 3-O-methyl-d-glucose uptake) by 25% in crown gall tumors induced on potato tuber tissue by Agrobacterium tumefaciens strain C 58. The titration of the endogenous IAA with the auxin antagonist 2-naphthaleneacetic acid at 100 micromolars reduces d-glucose uptake by about 80%. The apparent inhibition constant K(i) is 21 micromolars. Other auxin antagonists like 1-naphthoxyacetic acid and 2-(p-chlorophenoxy)-2-methylpropionic acid show similar effects. The uptake of the amino acids leucine, methionine, tryptophan, lysine, and aspartic acid is also inhibited by 2-naphthaleneacetic acid to similar degrees. The auxins 1-naphthaleneacetic acid and 2-naphthoxyacetic acid at concentrations between 10 and 100 micromolars inhibit solute uptake only slightly (inhibition less than 20%). The impact of the results on the postulated role of indole-3-acetic acid as a modifier of the electrochemical proton gradient across the plasmalemma in crown gall tumor tissue is discussed.

  7. Stabilizing effect of citrate buffer on the photolysis of riboflavin in aqueous solution

    PubMed Central

    Ahmad, Iqbal; Sheraz, Muhammad Ali; Ahmed, Sofia; Kazi, Sadia Hafeez; Mirza, Tania; Aminuddin, Mohammad

    2011-01-01

    In the present investigation the photolysis of riboflavin (RF) in the presence of citrate species at pH 4.0–7.0 has been studied. A specific multicomponent spectrophotometric method has been used to assay RF in the presence of photoproducts during the reactions. The overall first-order rate constants (kobs) for the photolysis of RF range from 0.42 to 1.08×10–2 min−1 in the region. The values of kobs have been found to decrease with an increase in citrate concentration indicating an inhibitory effect of these species on the rate of reaction. The second-order rate constants for the interaction of RF with total citrate species causing inhibition range from 1.79 to 5.65×10–3 M−1 min−1 at pH 4.0–7.0. The log k–pH profiles for the reactions at 0.2–1.0 M citrate concentration show a gradual decrease in kobs and the value at 1.0 M is more than half compared to that of k0, i.e., in the absence of buffer, at pH 5.0. Divalent citrate ions cause a decrease in RF fluorescence due to the quenching of the excited singlet state resulting in a decrease in the rate of reaction and consequently leading to the stabilization of RF solutions. The greater quenching of fluorescence at pH 4.0 compared to that of 7.0 is in accordance with the greater concentration of divalent citrate ions (99.6%) at that pH. The trivalent citrate ions exert a greater inhibitory effect on the rate of RF photolysis compared to that of the divalent citrate ions probably as a result of excited triplet state quenching. The values of second-order rate constants for the interaction of divalent and trivalent citrate ions are 0.44×10–2 and 1.06×10–3 M–1 min–1, respectively, indicating that the trivalent ions exert a greater stabilizing effect, compared to the divalent ions, on RF solutions. PMID:25755977

  8. Enhanced efficiency of inverted polymer solar cells by using solution-processed TiOx/CsOx cathode buffer layer.

    PubMed

    Zhou, Xiaodong; Fan, Xi; Sun, Xianke; Zhang, Yunli; Zhu, Ziqiang

    2015-01-01

    In this work, a double-buffer film of TiOx coated with CsOx (TiOx/CsOx) was solution prepared to be applied in poly(3-hexylthiophene):indene-C60 bisadduct (P3HT:ICBA) and P3HT:[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) inverted polymer solar cells (PSCs). Compared with TiOx films and CsOx films, the TiOx/CsOx double-buffer film exhibited a favorable energy-level alignment among TiOx, CsOx, and the electron acceptor of PCBM or ICBA a better surface morphology; and an enhanced wetting and adhesion property with a contact angle of 21.0°, leading to a higher electron mobility of 5.52 × 10(-3) cm(2) V(-1)·s(-1). Moreover, the P3HT:ICBA and P3HT:PCBM photovoltaic devices with the double-buffer film showed the best power conversion efficiency up to 5.65% and 3.76%, respectively. Our results not only present that the double-buffer film is superior than the single film of TiOx and CsOx, but also imply that the solution-processed film has a potential to be generally used in roll-to-roll processed organic photovoltaic devices.

  9. Partial molar volumes of some alpha-amino acids in aqueous sodium acetate solutions at 308.15 K.

    PubMed

    Wang, J; Yan, Z; Zhuo, K; Lu, J

    1999-08-30

    The apparent molar volumes V(2,phi) have been determined for glycine, DL-alpha-alanine, DL-alpha-amino-n-butyric acid, DL-valine and DL-leucine in aqueous solutions of 0.5, 1.0, 1.5 and 2.0 mol kg(-1) sodium acetate by density measurements at 308.15 K. These data have been used to derive the infinite dilution apparent molar volumes V(0)(2,phi) for the amino acids in aqueous sodium acetate solutions and the standard volumes of transfer, Delta(t)V(0), of the amino acids from water to aqueous sodium acetate solutions. It has been observed that both V(0)(2,phi) and Delta(t)V(0) vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids. These linear correlations have been utilized to estimate the contributions of the charged end groups (NH(3)(+), COO(-)), CH(2) group and other alkyl chains of the amino acids to V(0)(2,phi) and Delta(t)V(0). The results show that V(0)(2,phi) values for (NH(3)(+), COO(-)) groups increase with sodium acetate concentration, and those for CH(2) are almost constant over the studied sodium acetate concentration range. The transfer volume increases and the hydration number of the amino acids decreases with increasing electrolyte concentrations. These facts indicate that strong interactions occur between the ions of sodium acetate and the charged centers of the amino acids. The volumetric interaction parameters of the amino acids with sodium acetate were calculated in water. The pair interaction parameters are found to be positive and decreased with increasing alkyl chain length of the amino acids, suggesting that sodium acetate has a stronger dehydration effect on amino acids which have longer hydrophobic alkyl chains. These phenomena are discussed by means of the co-sphere overlap model.

  10. Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.

    PubMed

    In, Byunggyu; Hwang, Gi Won; Lee, Keun-Hyeung

    2016-09-15

    A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84×10(4)M(-1)) in aqueous buffered solutions. The detection limit (230nM, 5.98ppb) of the peptide-based sensor was much lower than the maximum allowable level (7.41μM) of aluminium ions in drinking water demanded by EPA. The binding mode of the peptide sensor with aluminium ions was characterized using ESI mass spectrometry, NMR titration, and pH titration experiments.

  11. Solution-processed In2S3 buffer layer for chalcopyrite thin film solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Lan; Lin, Xianzhong; Ennaoui, Ahmed; Wolf, Christian; Lux-Steiner, Martha Ch.; Klenk, Reiner

    2016-02-01

    We report a route to deposit In2S3 thin films from air-stable, low-cost molecular precursor inks for Cd-free buffer layers in chalcopyrite-based thin film solar cells. Different precursor compositions and processing conditions were studied to define a reproducible and robust process. By adjusting the ink properties, this method can be applied in different printing and coating techniques. Here we report on two techniques, namely spin-coating and inkjet printing. Active area efficiencies of 12.8% and 12.2% have been achieved for In2S3-buffered solar cells respectively, matching the performance of CdS-buffered cells prepared with the same batch of absorbers.

  12. Solution-dispersed CuO nanoparticles anode buffer layer: Effect of ultrasonic agitation duration on photovoltaic performance

    NASA Astrophysics Data System (ADS)

    Sabri, Nasehah Syamin; Yap, Chi Chin; Yahaya, Muhammad; Salleh, Muhamad Mat; Jumali, Mohammad Hafizuddin Haji

    2016-11-01

    The performance of inverted type hybrid organic solar cell based on poly(3-hexyltheopene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) can be improved by adding an anode buffer layer of copper oxide (CuO). CuO that serves as an electron blocking layer which could effectively reduce the charge recombination at the photoactive layer (P3HT:PCBM)/silver (Ag) interfaces. At the same time, Cuo anode buffer layer could accelerate the holes collection from the photoactive layer to the top electrode. In this study we investigated the effects of ultrasonic agitation duration in preparation of solution-dispersed CuO anode buffer layer on the performance of the devices with a configuration of fluorine tin oxide (FTO)/zinc oxide (ZnO) nanorod arrays/P3HT:PCBM/ CuO/Ag. Different durations of ultrasonic agitation (0, 5, 15 and 25 min) were used for CuO nanoparticles solution dispersion to obtain the optimum particle size distribution of CuO. It was found that the smallest average particle size of CuO was obtained by applying the ultrasonic agitation for longest duration of 25 min. The highest power conversion efficiency of 1.22% was recorded from the device incorporating with CuO anode buffer layer with the smallest average particle size. It is believed that CuO anode buffer layer with the smallest average particle size had the least agglomerates, thus leading to better film formation and contact surface area.

  13. Efficient quantum dot light-emitting diodes with solution-processable molybdenum oxide as the anode buffer layer.

    PubMed

    He, Shaojian; Li, Shusheng; Wang, Fuzhi; Wang, Andrew Y; Lin, Jun; Tan, Zhan'ao

    2013-05-03

    Quantum dot light-emitting diodes (QD-LEDs) are characterized by pure and saturated emission colors with narrow bandwidth. Optimization of the device interface is an effective way to achieve stable and high-performance QD-LEDs. Here we utilized solution-processed molybdenum oxide (MoOx) as the anode buffer layer on ITO to build efficient QD-LEDs. Using MoOx as the anode buffer layer provides the QD-LED with good Ohmic contact and a small charge transfer resistance. The device luminance is nearly independent of the thickness of the MoOx anode buffer layer. The QD-LEDs with a MoOx anode buffer layer exhibit a maximum luminance and luminous efficiency of 5230 cd m(-2) and 0.67 cd A(-1) for the yellow emission at 580 nm, and 7842 cd m(-2) and 1.49 cd A(-1) for the red emission at 610 nm, respectively.

  14. Changes in aggregation behavior of collagen molecules in solution with varying concentrations of acetic acid.

    PubMed

    Yang, Huan; Xu, Songcheng; Shen, Lirui; Liu, Wentao; Li, Guoying

    2016-11-01

    A critical aggregation concentration of 0.30-0.50mg/mL was previously obtained for type I collagen at 0.1M acetic acid (AA). In the present study, the aggregation behavior of collagen in solution (0.5mg/mL) in the presence of 0.1-2.0M AA was investigated. Circular dichroism showed that the three helix structure was maintained across the whole AA concentration range. However, the ratio of positive peak intensity over negative peak intensity varied depending on the conformational state of collagen aggregates. Ultra-sensitive differential scanning calorimetry revealed that transition temperatures Tm1 and Tm2 decreased by 8.35°C and 7.80°C, respectively, between 0.1M and 2.0M, indicating a possible relationship between the aggregation state and the thermal effect. The surrounding polarity of collagen molecules in solution containing pyrene was investigated by fluorescence spectroscopy, which demonstrated that disaggregation of collagen aggregates was enhanced with increasing AA concentration. This observation was correlated with changes in collagen fiber size observed by atomic force microscopy. Furthermore, collagen tyrosine residues were blue-shifted in an intrinsic fluorescence spectra, further indicating changes in aggregation behavior with increasing AA concentration. Finally, the dynamic response of collagen molecules to AA was analyzed by two-dimensional correlation fluorescence spectra.

  15. Nonclinical safety evaluation of boric acid and a novel borate-buffered contact lens multi-purpose solution, Biotrue™ multi-purpose solution.

    PubMed

    Lehmann, David M; Cavet, Megan E; Richardson, Mary E

    2010-12-01

    Multipurpose solutions (MPS) often contain low concentrations of boric acid as a buffering agent. Limited published literature has suggested that boric acid and borate-buffered MPS may alter the corneal epithelium; an effect attributed to cytotoxicity induced by boric acid. However, this claim has not been substantiated. We investigated the effect of treating cells with relevant concentrations of boric acid using two cytotoxicity assays, and also assessed the impact of boric acid on corneal epithelial barrier function by measuring TEER and immunostaining for tight junction protein ZO-1 in human corneal epithelial cells. Boric acid was also assessed in an in vivo ocular model when administered for 28 days. Additionally, we evaluated Biotrue multi-purpose solution, a novel borate-buffered MPS, alone and with contact lenses for ocular compatibility in vitro and in vivo. Boric acid passed both cytotoxicity assays and did not alter ZO-1 distribution or corneal TEER. Furthermore, boric acid was well-tolerated on-eye following repeated administration in a rabbit model. Finally, Biotrue multi-purpose solution demonstrated good ocular biocompatibility both in vitro and in vivo. This MPS was not cytotoxic and was compatible with the eye when administered alone and when evaluated with contact lenses. We demonstrate that boric acid and a borate-buffered MPS is compatible with the ocular environment. Our findings provide evidence that ocular effects reported for some borate-buffered MPS may be incorrectly attributed to boric acid and are more likely a function of the unique combination of ingredients in the MPS formulation tested.

  16. CHLORIDEDETERMINATION IN HIGH IONIC STRENGTH SOLUTION OF AMMONIUM ACETATE USING NEGATIVE ION ELECTRON SPRAY IONIZATION (HPLC/MS)

    EPA Science Inventory

    A precise ion chromatography method has been developed for the determination of chloride in high ionic strength ammonium acetate solutions (10-5 M-5 M) using sodium carbonate/sodium bicarbonate as eluent. Negative ion electrospray ionization (ESI) mass spectrometry was used for q...

  17. 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.

  18. An experimental determination of ferrous chloride and acetate complexation in aqueous solutions to 300°C

    NASA Astrophysics Data System (ADS)

    Palmer, Donald A.; Hyde, K. E.

    1993-04-01

    The formation of the monochloroiron(II) complex, FeCl +, was studied potentiometrically from 125 to 295°C at 25 degree intervals at one molal ionic strength in aqueous solutions containing acetic acid, sodium acetate, and sodium trifluoromethanesulfonate. In this method, competition between chloride and acetate ions for the ferrous cation resulted in a change in solution pH, which in turn was monitored in situ in a hydrogen-electrode, concentration cell. A simple empirical approach was used to extrapolate these formation quotients to infinite dilution. The resulting constants proved to be in excellent agreement with previous spectrophotometric results obtained from 25 to 200°C. Thus, the present study confirms the validity of the conclusions made based on these earlier data concerning the solubility of Fe-containing minerals in hydrothermal brines. Formation constants at infinite dilution for FeCl + are compared with the stability of ferrous acetate and hydroxide complexes. The original potentiometric titration data for ferrous acetate complex formation were combined in a new fit with values determined from the present study at unit ionic strength. Two empirical treatments (namely the isocoulombic method and the temperature/water density function) were considered for fitting and extrapolating the infinite dilution formation constants to 350°C.

  19. Stability and interface properties of thin cellulose ester films adsorbed from acetone and ethyl acetate solutions.

    PubMed

    Amim, Jorge; Kosaka, Priscila M; Petri, Denise F S; Maia, Francisco C B; Miranda, Paulo B

    2009-04-15

    Stability and interface properties of cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) films adsorbed from acetone or ethyl acetate onto Si wafers have been investigated by means of contact angle measurements and atomic force microscopy (AFM). Surface energy (gamma(S)(total)) values determined for CAP adsorbed from acetone are larger than those from ethyl acetate. In the case of CAB films adsorbed from ethyl acetate and acetone were similar. Dewetting was observed by AFM only for CAP films prepared from ethyl acetate. Positive values of effective Hamaker constant (A(eff)) were found only for CAP prepared from ethyl acetate, corroborating with dewetting phenomena observed by AFM. On the contrary, negative values of A(eff) were determined for CAP and CAB prepared from acetone and for CAB prepared from ethyl acetate, corroborating with experimental observations. Sum frequency generation (SFG) vibrational spectra indicated that CAP and CAB films prepared from ethyl acetate present more alkyl groups oriented perpendicularly to the polymer-air interface than those films prepared from acetone. Such preferential orientation corroborates with macroscopic contact angle measurements. Moreover, SFG spectra showed that acetone binds strongly to Si wafers, creating a new surface for CAP and CAB films.

  20. Proposing buffer zones and simple technical solutions for safeguarding river water quality and public health

    NASA Astrophysics Data System (ADS)

    Podimata, M. V.; Bekri, E. S.; Yannopoulos, P. C.

    2012-04-01

    Alfeios River Basin (ARB) constitutes one of the major hydrologic basins (≈3650km2) of Peloponnisos peninsula in Southern Greece. It is drained by Alfeios River and its tributaries, such as Lousios, Ladhon, Erymanthos, Kladheos, Selinous etc. The present manuscript takes a closer look at the importance of tributary basins and focuses on Erymanthos sub-basin that covers about 360 km2. Erymanthos River springs from Erymanthos Mountain that reaches altitudes of 2200 m and discharges 10 m3/sec, approximately, during the winter period, presenting a sound decrease from half to about an order of magnitude during summertime. Two factors stand out as reasons to select Erymanthos sub-basin as a case study. First, the sub-basin presents a significant variety of ecosystems and comprises a very important river system, since Erymanthos Tributary satisfies, among other uses, drinking water supply for a great majority of citizens in the region. Second, authors' experience of the study area in Research Program Pythagoras II, funded by the European Social Fund (ESF) and the Operational Program for Educational and Vocational Training II (EPEAEK II) of Greece, offers a basis for better understanding of the real problems in the area. Erymanthos watershed, in fact, faces a lot of pressures, in several levels, provoked by human activities and Erymanthos Tributary is vulnerable to pollution. Recognizing the importance of clean water for healthy people, a developing economy, and a sustainable environment, the challenge of the present paper is elaborating human-induced pressures in the study area, analyzing their effects, estimating pollution factors and proposing integrated solutions/tools and a number of methodologies/initiatives used to overcome the problem of contaminating water supply in a catchment that lacks of wastewater treatment and disposal systems. The preservation of a good ecological status in Erymanthos River is not only a necessity for achieving the goals of EU Water

  1. 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

  2. Size Control of (99m)Tc-tin Colloid Using PVP and Buffer Solution for Sentinel Lymph Node Detection.

    PubMed

    Kim, Eun-Mi; Lim, Seok Tae; Sohn, Myung-Hee; Jeong, Hwan-Jeong

    2015-06-01

    Colloidal particle size is an important characteristic that allows mapping sentinel nodes in lymphoscintigraphy. This investigation aimed to introduce different ways of making a (99m)Tc-tin colloid with a size of tens of nanometers. All agents, tin fluoride, sodium fluoride, poloxamer-188, and polyvinylpyrrolidone (PVP), were mixed and labeled with (99m)Tc. Either phosphate or sodium bicarbonate buffers were used to adjust the pH levels. When the buffers were added, the size of the colloids increased. However, as the PVP continued to increase, the size of the colloids was controlled to within tens of nanometers. In all samples, phosphate buffer added PVP (30 mg) stabilized tin colloid ((99m)Tc-PPTC-30) and sodium bicarbonate solution added PVP (50 mg) stabilized tin colloid ((99m)Tc-BPTC-50) were chosen for in vitro and in vivo studies. (99m)Tc-BPTC-50 (<20 nm) was primarily located in bone marrow and was then secreted through the kidneys, and (99m)Tc-PPTC-30 (>100 nm) mainly accumulated in the liver. When a rabbit was given a toe injection, the node uptake of (99m)Tc-PPTC-30 decreased over time, while (99m)Tc-BPTC-50 increased. Therefore, (99m)Tc-BPTC-50 could be a good candidate radiopharmaceutical for sentinel node detection. The significance of this study is that nano-sized tin colloid can be made very easily and quickly by PVP.

  3. On the Electrochemical Behavior of PVD Ti-Coated AISI 304 Stainless Steel in Borate Buffer Solution

    NASA Astrophysics Data System (ADS)

    Fattah-alhosseini, Arash; Elmkhah, Hassan; Attarzadeh, Farid Reza

    2017-03-01

    This work aims at studying the electrochemical behavior of annealed pure titanium (Ti) and nano-structured (NS) Ti coating in borate buffer solutions. Cathodic arc evaporation was successfully applied to deposit NS Ti coating. Samples were characterized by means of scanning electron microscope and x-ray diffraction. Potentiodynamic polarization tests, electrochemical impedance spectroscopy, and Mott-Schottky analysis were employed to discuss the electrochemical behavior of samples thoroughly. Electrochemical measurements showed that the deposited NS Ti coating offers a superior passivity in borate buffer solutions of pH 9.0 and 9.5. Mott-Schottky analysis revealed that all passive films are of n-type semiconducting nature in these alkaline solutions and the deposition process did not alter the semiconducting type of passive films formed on samples. Additionally, this analysis showed that the NS Ti coating possessed lower levels of donor densities. Finally, all electrochemical tests showed that passive behavior of the NS Ti samples was superior, mainly due to the formation of thicker and less defective passive films.

  4. The potentiometric determination of stability constants for zinc acetate complexes in aqueous solutions to 295°C

    NASA Astrophysics Data System (ADS)

    Glordano, Thomas H.; Drummond, S. E.

    1991-09-01

    A potentiometric method was used to determine the formation quotients of zinc acetate complexes in aqueous solutions from 50 to 295°C at ionic strengths of 0.03,0.3, and 1.0 m. The potentiometric titrations were carried out in an externally heated, Teflon-lined concentration cell fitted with hydrogen electrodes. Formal sodium acetate concentrations of the experimental solutions ranged from 0.001 to 0. 1 m with acetic acid to sodium acetate ratios ranging from 30 to 300. Sodium trifluoromethanesulfonate (F3CSO3Na) was used as a supporting electrolyte. Stoichiometries and formation quotients for the complexes ZnCH3COO+, Zn(CH3COO)2, and Zn(CH3COO)-3 were derived from the titration data by regression analysis. Stability constants at infinite dilution (Kn) and other relevant thermodynamic quantities were calculated for these three complexes. Logarithms for the formation constants of the general reaction Zn2+ + nCH3COO- = Zn(CH3COO)n2-n are n = 1-(1.9 ± 0.2, 50°C), (2.3 ± 0.1, 100°C), (2.8 ± 0.1, 150°C), (3.5 ± 0.1, 200°C), (4.3 ± 0.2, 250°C), (5.3 ± 0.3, 300°C); n = 2-(3.4 ± 0.1, 50°C), (4.0 ± 0.1, 100°C), (4.83 ± 0.09, 150°C), (5.9 ± 0.1, 200°C), (7.1 ± 0.1, 250°C), (8.7 ± 0.2, 300°C); n = 3-(4.1 ± 0.3, 50°C), (4.7 ± 0.3, 100°C), (5.5 ± 0.3, 150°C), (6.6 ± 0.3, 200°C), (7.9 ± 0.3, 250°C), (9.4 ± 0.3, 300°C). Calculations of zinc speciation in acetate-chloride solutions show that zinc acetate complexes should have an importance similar to zinc chloride complexes in high acetate waters where chloride to acetate molal ratios are less than about 10.

  5. Antibacterial and photocatalytic activity of TiO2 and ZnO nanomaterials in phosphate buffer and saline solution.

    PubMed

    Ng, Alan Man Ching; Chan, Charis May Ngor; Guo, Mu Yao; Leung, Yu Hang; Djurišić, Aleksandra B; Hu, Xu; Chan, Wai Kin; Leung, Frederick Chi Chung; Tong, Shuk Yin

    2013-06-01

    We studied antibacterial and photocatalytic activity of anatase TiO2 and ZnO in phosphate buffer and saline solution. We found that the different anions in the suspension medium (chloride and phosphate) significantly affected the following suspension properties: the stability of nanoparticle suspension, the release of metal ions from the nanoparticles, and the production of the reactive oxygen species by the nanoparticles. As a result, antibacterial activity and photocatalytic dye degradation were also affected. However, the effect of the suspension medium was different for ZnO and TiO2. Obtained results are discussed.

  6. Photoelectrochemical study of pitting on iron in borate buffer solution containing inhibitor

    SciTech Connect

    Yang, M.; Chen, L.; Cai, S.

    1997-01-01

    The photoelectrochemical behavior and the susceptibility of iron to pitting in borate buffer containing chloride ions (Cl{sup {minus}}) were investigated in the presence and absence of inhibitor PC-604, which is a mixture of polyhydric alcohol phosphoric easter and polyphosphoric ester of various molecular weights. Measurements of the band gap (E{sub g}) of the passive film on iron showed inhibitor concentration and passivation time did not interfere with E{sub g}. Photocurrent and photocurrent transients increased with increasing inhibitor quantities and passivation times at constant potential. The decay time-constant of the photocurrent transient was investigated as a specific parameter of the film. Data showed this parameter was related to pitting susceptibility of the passive film on iron.

  7. Decontamination of aquatic vegetable leaves by removing trace toxic metals during pickling process with acetic acid solution.

    PubMed

    Wu, Wenbiao; Yang, Yixing

    2011-01-01

    The heavy-metal content of aquatic plants is mainly dependent upon their ecological system. This study indicated that although the toxic heavy-metal contents could be above the recommended maximum levels depending upon their concentrations in growing water, they can be decontaminated by pickling with 5% acetic acid solution. Almost all Cd, Hg, Ba, or Sb and 99.5% Pb, 96.7% Ag, or 97.1% Al were removed from Water Spinach leaves by soaking in acetic acid solution. For Water-Shield leaves, almost all Cd, Hg, Pb, Ba, or Sb and 95.0% Ag or 96.1% Al were removed. For Watercress leaves, almost all Cd, Hg, Ba, or Sb and 99.0% Pb or 99.7% Ag were removed. For Water Hyacinth leaves, almost all Cd, Ba, or Sb and 99.0% Hg, 98.5% Pb, 95.0% Ag, or 98.7% Al were removed.

  8. 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.

  9. 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.

  10. Aqueous Chemical Solution Deposition of Novel, Thick and Dense Lattice-Matched Single Buffer Layers Suitable for YBCO Coated Conductors: Preparation and Characterization

    PubMed Central

    Narayanan, Vyshnavi; Van Steenberge, Sigelinde; Lommens, Petra; Van Driessche, Isabel

    2012-01-01

    In this work we present the preparation and characterization of cerium doped lanthanum zirconate (LCZO) films and non-stoichiometric lanthanum zirconate (LZO) buffer layers on metallic Ni-5% W substrates using chemical solution deposition (CSD), starting from aqueous precursor solutions. La2Zr2O7 films doped with varying percentages of Ce at constant La concentration (La0.5CexZr1−xOy) were prepared as well as non-stoichiometric La0.5+xZr0.5−xOy buffer layers with different percentages of La and Zr ratios. The variation in the composition of these thin films enables the creation of novel buffer layers with tailored lattice parameters. This leads to different lattice mismatches with the YBa2Cu3O7−x (YBCO) superconducting layer on top and with the buffer layers or substrate underneath. This possibility of minimized lattice mismatch should allow the use of one single buffer layer instead of the current complicated buffer architectures such as Ni-(5% W)/LZO/LZO/CeO2. Here, single, crack-free LCZO and non-stoichiometric LZO layers with thicknesses of up to 140 nm could be obtained in one single CSD step. The crystallinity and microstructure of these layers were studied by XRD, and SEM and the effective buffer layer action was studied using XPS depth profiling.

  11. CHARACTERISTICS OF POROUS CELLULOSE ACETATE MEMBRANES FOR THE SEPARATION OF SOME INORGANIC SALTS IN AQUEOUS SOLUTION,

    DTIC Science & Technology

    Experimental results are presented to illustrate the effect of operating variables on the separation and flow characteristics of porous cellulose ... acetate membranes. The results are discussed from the point of view of the preferential sorption and capillary flow mechanism, together with the concept

  12. Tuning of the selectivity of fluorescent peptidyl bioprobe using aggregation induced emission for heavy metal ions by buffering agents in 100% aqueous solutions.

    PubMed

    Neupane, Lok Nath; Hwang, Gi Won; Lee, Keun-Hyeung

    2017-02-03

    Smart fluorescent probes of which the detection of specific target molecules can be controlled are attracting remarkable interest. A fluorescent peptidyl bioprobe (1) was rationally synthesized by conjugating tetraphenylethylene, an aggregation-induced emission (AIE) fluorophore with a peptide receptor (AspHis) that acted as hard and intermediate bases. The selective detection of 1 for specific metal ion in 100% aqueous solutions was controlled by the buffering agents with the chelate effect without the change of pH. In distilled water and phosphate buffered aqueous solution at neutral pH, 1 exhibited a selective Off-On response to a soft metal ion, Hg(2+) among test metal ions by 100-fold enhancement of the emission at 470nm. 1 showed a selective Off-On response (180-fold enhancement) to a hard metal ion, Al(3+) ions among test metal ions in Tris buffered aqueous solution at neutral pH and Hexamine (hexamethylenetetramine) buffered aqueous solution at acidic pH. The detection limit of 0.46 ppb for Hg(2+) and 2.26 ppb for Al(3+) in each condition was lower than the maximum allowable level of the metal ions in drinking water by EPA. This research helps to understand how buffering agents participate in the complex formation and aggregation of fluorescent probes using an AIE process for the selective detection of specific metal ions in aqueous solutions.

  13. Electrochemical Behavior of Pure Copper in Phosphate Buffer Solutions: A Comparison Between Micro- and Nano-Grained Copper

    NASA Astrophysics Data System (ADS)

    Imantalab, O.; Fattah-alhosseini, A.; Keshavarz, M. K.; Mazaheri, Y.

    2016-02-01

    In this work, electrochemical behavior of annealed (micro-) and nano-grained pure copper (fabricated by accumulative roll bonding process) in phosphate buffer solutions of various pH values ranging from 10.69 to 12.59 has been studied. Before any electrochemical measurements, evaluation of microstructure was obtained by optical microscope and transmission electron microscopy. To investigate the electrochemical behavior of the samples, the potentiodynamic polarization, Mott-Schottky analysis, and electrochemical impedance spectroscopy (EIS) were carried out. Potentiodynamic polarization plots and EIS measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure copper. Also, Mott-Schottky analysis indicated that the passive films behaved as p-type semiconductors and grain refinement did not change the semiconductor type of passive films.

  14. Effect of Phosphate-Buffered Solution Corrosion on the Ratcheting Fatigue Behavior of a Duplex Mg-Li-Al Alloy

    NASA Astrophysics Data System (ADS)

    Yuan, Xin; Yu, Dunji; Gao, Li-Lan; Gao, Hong

    2016-05-01

    This work reports the uniaxial ratcheting and fatigue behavior of a duplex Mg-Li-Al alloy under the influence of phosphate-buffered solution corrosion. Microstructural observations reveal pitting and filament corrosion defects, which impair the load-bearing capacity of the alloy and cause stress concentration, thus leading to an accelerated accumulation of ratcheting strain and shortened fatigue life under the same nominal loading conditions. Comparing Smith model, Smith-Watson-Topper model, and Paul-Sivaprasad-Dhar model, a ratcheting fatigue life prediction model based on the Broberg damage rule and the Paul-Sivaprasad-Dhar model was proposed, and the model yielded a superior prediction for the studied magnesium alloy.

  15. A simple ratiometric and colorimetric chemosensor for the selective detection of fluoride in DMSO buffered solution

    NASA Astrophysics Data System (ADS)

    Niu, Hu; Shu, Qinghai; Jin, Shaohua; Li, Bingjun; Zhu, Jiaping; Li, Lijie; Chen, Shusen

    2016-01-01

    A derivative of squaramide (cyclobuta[b]quinoxaline-1, 2(3H, 8H)-dione) has been synthesized for the ratiometric and colorimetric sensing of F- in aqueous solution in competitive fashion. With F-, probe 1 showed a highly selective naked-eye detectable color change along with a characteristic UV-Vis absorbance over other tested ions, which probably originates from the deprotonation occurred between 1 and F-, as proved by the 1H NMR titration experiments and DFT calculations.

  16. Chemiluminescence flow biosensor for glucose using Mg-Al carbonate layered double hydroxides as catalysts and buffer solutions.

    PubMed

    Wang, Zhihua; Liu, Fang; Lu, Chao

    2012-01-01

    In this work, serving as supports in immobilizing luminol reagent, catalysts of luminol chemiluminescence (CL), and buffer solutions for the CL reaction, Mg-Al-CO(3) layered double hydroxides (LDHs) were found to trigger luminol CL in weak acid solutions (pH 5.8). The silica sol-gel with glucose oxidase and horseradish peroxidase was immobilized in the first half of the inside surface of a clear quartz tube, and luminol-hybrid Mg-Al-CO(3) LDHs were packed in the second half. Therefore, a novel CL flow-through biosensor for glucose was constructed in weak acid solutions. The CL intensity was linear with glucose concentration in the range of 0.005-1.0mM, and the detection limit for glucose (S/N=3) was 0.1 μM. The proposed biosensor exhibited excellent stability, high reproducibility and high selectivity for the determination of glucose and has been successfully applied to determine glucose in human plasma samples with satisfactory results. The success of this work has broken the bottleneck of the pH incompatibility between luminol CL and enzyme activity.

  17. Removal of dicyclohexyl acetic acid from aqueous solution using ultrasound, ozone and their combination.

    PubMed

    Kumar, Pardeep; Headley, John; Peru, Kerry; Bailey, Jon; Dalai, Ajay

    2014-01-01

    Naphthenic acids are a complex mixture of organic components, some of which include saturated alkyl-substituted cycloaliphatic carboxylic acids and acyclic aliphatic acids. They are naturally found in hydrocarbon deposits like oil sand, petroleum, bitumen and crude oil. In this study, the oxidation of a relatively high molecular weight naphthenic acid (Dicyclohexyl acetic acid) was investigated using ozonation, ultrasonication and hydrogen peroxide alone and their combinations. Effects on oxidation of dicyclohexyl acetic acid (DAA) were measured for different concentrations of ozone ranging between 0.7 to 3.3 mg L(-1) and pH in the range 6 to 10. Ultrasonication and hydrogen peroxide alone were not effective to oxidize dicyclohexyl acetic acid, but combining ultrasonication with H2O2 had a significant effect on oxidation of dicyclohexyl acetic acid with maximum removal reaching to 84 ± 2.2% with 81 ± 2.1% reduction in chemical oxygen demand (COD). Synergistic effects were observed for combining ultrasonication with ozonation and resulted in 100% DAA removal with 98 ± 0.8% reduction in COD within 15 min at 3.3 mg L(-1) ozone concentration and 130 Watts ultrasonication power. The reaction conditions obtained for the maximum oxidation of DAA and COD removal were used for the degradation of naphthenic acids mixture extracted from oil sands process water (OSPW). The percentage oxidation of NAs mixture extracted from OSPW was 89.3 ± 1.1% in ozonation and combined ozonation and ultrasonication, but COD removal observed was 65 ± 1.2% and 78 ± 1.4% for ozonation and combined ozonation and ultrasonication treatments, respectively.

  18. Interfacial energetics of globular–blood protein adsorption to a hydrophobic interface from aqueous-buffer solution

    PubMed Central

    Krishnan, Anandi; Liu, Yi-Hsiu; Cha, Paul; Allara, David; Vogler, Erwin A

    2005-01-01

    Adsorption isotherms of nine globular proteins with molecular weight (MW) spanning 10–1000 kDa confirm that interfacial energetics of protein adsorption to a hydrophobic solid/aqueous-buffer (solid–liquid, SL) interface are not fundamentally different than adsorption to the water–air (liquid–vapour, LV) interface. Adsorption dynamics dampen to a steady-state (equilibrium) within a 1 h observation time and protein adsorption appears to be reversible, following expectations of Gibbs' adsorption isotherm. Adsorption isotherms constructed from concentration-dependent advancing contact angles θa of buffered-protein solutions on methyl-terminated, self-assembled monolayer surfaces show that maximum advancing spreading pressure, Πamax, falls within a relatively narrow 10<Πamax<20mNm−1 band characteristic of all proteins studied, mirroring results obtained at the LV surface. Furthermore, Πa isotherms exhibited a ‘Traube-rule-like’ progression in MW similar to the ordering observed at the LV surface wherein molar concentrations required to reach a specified spreading pressure Πa decreased with increasing MW. Finally, neither Gibbs' surface excess quantities [Γsl−Γsv] nor Γlv varied significantly with protein MW. The ratio {[Γsl−Γsv]/Γlv}∼1, implying both that Γsv∼0 and chemical activity of protein at SL and LV surfaces was identical. These results are collectively interpreted to mean that water controls protein adsorption to hydrophobic surfaces and that the mechanism of protein adsorption can be understood from this perspective for a diverse set of proteins with very different composition. PMID:16849238

  19. Nanofiltration of rhodium tris(triphenylphosphine) catalyst in ethyl acetate solution

    NASA Astrophysics Data System (ADS)

    Shaharun, Maizatul S.; Mustafa, Ahmad K.; Taha, Mohd F.

    2012-09-01

    Solvent resistant nanofiltration (SRNF) using polymer membranes has recently received enhanced attention due to the search for cleaner and more energy-efficient technologies. The large size of the rhodium tris(triphenylphosphine) [HRh(CO)(PPh3)3] catalyst (>400 Da) - relative to other components of the hydroformylation reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (DuraMem{trade mark, serif} 200 and DuraMem{trade mark, serif} 500) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. Good HRh(CO)(PPh3)3 rejection (>0.95) and solvent fluxes of 9.9 L/m2ṡh1 at 2.0 MPa were obtained in the catalyst-ethyl acetate-DuraMem 500 system. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted on the catalyst-ethyl acetate-membrane systems. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting solvent flux.

  20. 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

  1. 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.

  2. Michrochip chromatography using an open-tubular microchannel and a ternary water-ACN-ethyl acetate mixture carrier solution.

    PubMed

    Matsuda, Takafumi; Yamashita, Kenichi; Maeda, Hideaki; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

    2013-03-01

    A capillary chromatography system has been developed using a ternary mixed-solvents solution, i.e. water-hydrophilic/hydrophobic organic solvent mixture as a carrier solution. Here, we tried to carry out the chromatographic system on a microchip incorporating the open-tubular microchannels. A model analyte solution of isoluminol isothiocyanate (ILITC) and ILITC-labeled biomolecule was injected to the double T-junction part on the microchip. The analyte solution was delivered in the separation microchannel (40 μm deep, 100 μm wide, and 22 cm long) with the ternary water-ACN-ethyl acetate mixture carrier solution (3:8:4 volume ratio, the organic solvent rich or 15:3:2 volume ratio, the water-rich). The analyte, free-ILITC and labeled BSA mixture, was separated through the microchannel, where the carrier solvents were radially distributed in the separation channel generating inner and outer phases. The outer phase acts as a pseudo-stationary phase under laminar flow conditions in the system. The ILITC and the labeled BSA were eluted and detected with chemiluminescence reaction.

  3. Preparation of SmBiO3 buffer layer on YSZ substrate by an improved chemical solution deposition route

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaolei; Pu, Minghua; Zhao, Yong

    2016-12-01

    A quick route for chemical solution deposition (CSD) has been developed to prepare SmBiO3 (SBO) layers on yttria stabilized zirconia (YSZ) substrates rapidly by using of solid state decomposition (SSD) technique. The proper conditions for volatilization of lactic acid, which as solvent in precursor coated layer, and SBO growth are 115°C for 30 min and 794°C for 60 min in flowing Ar gas. The coated layers are amorphous structure of mixture oxides and quasi-crystal structure of SBO before and after growth, respectively. The total time by this quick CSD route for organic solvent volatilization, salts decomposed and layer growth is not up to 2 h, which are much less than that needed for traditional CSD of over 10 h. SBO layer is directly epitaxial growth on YSZ substrate without any lattice rotation. SBO layer prepared by this quick route as well as that by traditional route are suitable for the growth of YBCO. The superconducting transition temperature and critical current density of the coated YBCO layer on SBO/YSZ obtained by this quick route are up to 90 K and 1.66 MA/cm2. These results may be the usable reference for continuous preparation of SBO buffer layer on IBAD-YSZ/Ni-based alloy tapes.

  4. Biosorption of formic and acetic acids from aqueous solution using activated carbon from shea butter seed shells

    NASA Astrophysics Data System (ADS)

    Adekola, Folahan A.; Oba, Ismaila A.

    2016-10-01

    The efficiency of prepared activated carbon from shea butter seed shells (SB-AC) for the adsorption of formic acid (FA) and acetic acid (AA) from aqueous solution was investigated. The effect of optimization parameters including initial concentration, agitation time, adsorbent dosage and temperature of adsorbate solution on the sorption capacity were studied. The SB-AC was characterized for the following parameters: bulk density, moisture content, ash content, pH, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optimal conditions for the adsorption were established and the adsorption data for AA fitted Dubinin-Radushkevich (D-R) isotherm well, whereas FA followed Langmuir isotherm. The kinetic data were examined. It was found that pseudo-second-order kinetic model was found to adequately explain the sorption kinetic of AA and FA from aqueous solution. It was again found that intraparticle diffusion was found to explain the adsorption mechanism. Adsorption thermodynamic parameters were estimated and the negative values of ∆G showed that the adsorption process was feasible and spontaneous in nature, while the negative values of ∆H indicate that the adsorption process was exothermic. It is therefore established that SB-AC has good potential for the removal of AA and FA from aqueous solution. Hence, it should find application in the regular treatment of polluted water in aquaculture and fish breeding system.

  5. Facilitated transport of basic and acidic drugs in solutions through snakeskin by a new enhancer--dodecyl N,N-dimethylamino acetate.

    PubMed

    Fleeker, C; Wong, O; Rytting, J H

    1989-06-01

    The permeation characteristics of two model drugs, clonidine (basic) and indomethacin (acidic), were studied by determining their penetration fluxes through hydrated shed snakeskins (Elaphe obsoleta) at 32 degrees C. The drugs were formulated in buffers of different pH's, ranging from 3 to 7. The total penetration fluxes at pH 7.0 for both compounds using skins pretreated with dodecyl N,N-dimethylamino acetate were at least 11 times higher than those of the control runs without enhancer treatment. Equations were derived to calculate the permeability coefficients (Ki) and fluxes (Ji) for the ionized and the nonionized species to allow for comparison of their penetration ability through the model membrane. The permeability coefficient of clonidine is 2.50 x 10(-3) cm/hr for the nonionized form and 2.41 x 10(-4) cm/hr for the protonated form. This result indicates that the nonionized form penetrates the skins better than the ionized form. Both permeability coefficient values are 11 times larger than the corresponding values obtained from the control skins. The total flux of clonidine is dependent on its initial concentration in the donor cell but is independent of the ionic strength of the solution formulations. The penetration characteristics of indomethacin are similar to those of clonidine, with a higher permeability coefficient of the nonionized form (3.90 x 10(-3) cm/hr) than of the ionized form (7.97 x 10(-4) cm/hr) using pretreated skins. While the enhancer shows 24 times penetration enhancement of the ionized form of indomethacin, it does not enhance the penetration of the nonionized species.

  6. Plasma acetate, gluconate and interleukin-6 profiles during and after cardiopulmonary bypass: a comparison of Plasma-Lyte 148 with a bicarbonate-balanced solution

    PubMed Central

    2011-01-01

    Introduction As even small concentrations of acetate in the plasma result in pro-inflammatory and cardiotoxic effects, it has been removed from renal replacement fluids. However, Plasma-Lyte 148 (Plasma-Lyte), an electrolyte replacement solution containing acetate plus gluconate is a common circuit prime for cardio-pulmonary bypass (CPB). No published data exist on the peak plasma acetate and gluconate concentrations resulting from the use of Plasma-Lyte 148 during CPB. Methods Thirty adult patients were systematically allocated 1:1 to CPB prime with either bicarbonate-balanced fluid (24 mmol/L bicarbonate) or Plasma-Lyte 148. Arterial blood acetate, gluconate and interleukin-6 (IL-6) levels were measured immediately before CPB (T1), three minutes after CPB commencement (T2), immediately before CPB separation (T3), and four hours post separation (T4). Results Acetate concentrations (normal 0.04 to 0.07 mmol/L) became markedly elevated at T2, where the Plasma-Lyte group (median 3.69, range (2.46 to 8.55)) exceeded the bicarbonate group (0.16 (0.02 to 3.49), P < 0.0005). At T3, levels had declined but the differential pattern remained apparent (Plasma-Lyte 0.35 (0.00 to 1.84) versus bicarbonate 0.17 (0.00 to 0.81)). Normal circulating acetate concentrations were not restored until T4. Similar gluconate concentration profiles and inter-group differences were seen, with a slower T3 decay. IL-6 increased across CPB, peaking at T4, with no clear difference between groups. Conclusions Use of acetate containing prime solutions result in supraphysiological plasma concentrations of acetate. The use of acetate-free prime fluid in CPB significantly reduced but did not eliminate large acetate surges in cardiac surgical patients. Complete elimination of acetate surges would require the use of acetate free bolus fluids and cardioplegia solutions. Trial registration Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610000267055 PMID:21235742

  7. Corrosion-related changes on Ti-based orthodontic brackets in acetic NaF solutions: surface morphology, microhardness, and element release.

    PubMed

    Kang, Eun-Hee; Park, Soo-Byung; Kim, Hyung-Il; Kwon, Yong Hoon

    2008-07-01

    This study sought to investigate the effects of acetic NaF solutions on titanium and Ti alloy brackets. To this end, two different brackets were immersed in various NaF-containing solutions for three days. The Equilibrium Ti (EQ) bracket was composed of Ti only, whereas the Ortho 2 (OR) bracket was composed of Ti (base) and Ti-6A1-4V (wings). Brackets that were immersed in the acetic NaF solution of pH 3.5 yielded no reliable surface microhardness values due to corrosion. In other test solutions, however, there was minimal reduction (at best 3%) in microhardness. Further on microhardness, the values of the OR bracket at the base and wings were different. On the release of elements, it was significant only in the acetic NaF solution of pH 3.5. However, the release of Al (6.11+/-0.93 ppm) and V (1.16+/-0.40 ppm) in this solution was low. In conclusion, an acetic NaF solution of low pH could damage Ti-based orthodontic brackets.

  8. Inhibitory effect of hydroxypropyl methylcellulose acetate succinate on drug recrystallization from a supersaturated solution assessed using nuclear magnetic resonance measurements.

    PubMed

    Ueda, Keisuke; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu

    2013-10-07

    We examined the inhibitory effect of hydroxypropyl methylcellulose acetate succinate (HPMC-AS) on drug recrystallization from a supersaturated solution using carbamazepine (CBZ) and phenytoin (PHT) as model drugs. HPMC-AS HF grade (HF) inhibited the recrystallization of CBZ more strongly than that by HPMC-AS LF grade (LF). 1D-1H NMR measurements showed that the molecular mobility of CBZ was clearly suppressed in the HF solution compared to that in the LF solution. Interaction between CBZ and HF in a supersaturated solution was directly detected using nuclear Overhauser effect spectroscopy (NOESY). The cross-peak intensity obtained using NOESY of HF protons with CBZ aromatic protons was greater than that with the amide proton, which indicated that CBZ had hydrophobic interactions with HF in a supersaturated solution. In contrast, no interaction was observed between CBZ and LF in the LF solution. Saturation transfer difference NMR measurement was used to determine the interaction sites between CBZ and HF. Strong interaction with CBZ was observed with the acetyl substituent of HPMC-AS although the interaction with the succinoyl substituent was quite small. The acetyl groups played an important role in the hydrophobic interaction between HF and CBZ. In addition, HF appeared to be more hydrophobic than LF because of the smaller ratio of the succinoyl substituent. This might be responsible for the strong hydrophobic interaction between HF and CBZ. The intermolecular interactions between CBZ and HPMC-AS shown by using NMR spectroscopy clearly explained the strength of inhibition of HPMC-AS on drug recrystallization.

  9. Morphological and phase evolution of TiO 2 nanocrystals prepared from peroxotitanate complex aqueous solution: Influence of acetic acid

    NASA Astrophysics Data System (ADS)

    Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

    2009-04-01

    Nanosized anatase and rutile TiO 2 having different shape, phase and size have been prepared from aqueous solutions of peroxo titanium complex starting from titanium(IV) isopropoxide (TTIP), acetic acid and hydrogen peroxide (H 2O 2) in water/isopropanol media by a facile sol-gel process. The TiO 2 nanocrystals are characterized by powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, TEM, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques. The influence of pH and the sequence of addition of reaction contents on the phase and morphology of TiO 2 are studied. The reasons for the observation of only anatase and/or mixture of anatase and rutile are given.

  10. Contribution of solution pH and buffer capacity to suppress intergranular stress corrosion cracking of sensitized type 304 stainless steel at 95 C

    SciTech Connect

    Zhang, S.; Shibata, T.; Haruna, T. . Dept. of Materials Science and Processing)

    1999-05-01

    Controlling pH of high-temperature water to [approximately]pH 7 at 300 C by adding lithium hydroxide (LiOH) into the coolant system of a pressurized water reactor (PWR) successfully has been mitigating the corrosion of PWR component materials. The effects of solution pH and buffer capacity on intergranular stress corrosion cracking (IGSCC) of sensitized type 304 stainless steel ([SS] UNS S30400) was examined at 95 C by slow strain rate technique (SSRT) with an in-situ cracking observation system. It was found that an increase in solution pH or buffer capacity increased crack initiation time and decreased mean crack initiation frequency, but exerted almost no effect on crack propagation. This inhibition effect on IGSCC initiation was explained as resulting from a retarding effect of solution pH and buffer capacity on the decrease in pH at crack nuclei caused by the hydrolysis of metal ions dissolved when the passive film was ruptured by strain in SSRT.

  11. Influence of the chloride ion concentration on the corrosion of high-purity Mg, ZE41 and AZ91 in buffered Hank's solution.

    PubMed

    Taltavull, C; Shi, Z; Torres, B; Rams, J; Atrens, A

    2014-02-01

    This research studied the influence of the chloride ion concentration on the corrosion behaviour of high-purity magnesium (Mg) and two Mg alloys in Hank's solution, using hydrogen evolution and weight loss. A buffer based on CO2 and NaHCO3 was used to maintain the pH constant. The corrosion behaviour was governed by a partially protective surface film, and film breakdown by the chloride ions. The carbonated calcium phosphate layer that formed in Hank's solution was important in determining the protective properties of the surface film.

  12. TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: Phase diagrams and molecular dynamic simulations

    NASA Astrophysics Data System (ADS)

    Taha, Mohamed; Lee, Ming-Jer

    2013-06-01

    Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol/acetonitrile/acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.

  13. Multistate outbreak of fungal infection associated with injection of methylprednisolone acetate solution from a single compounding pharmacy - United States, 2012.

    PubMed

    2012-10-19

    On September 18, 2012, the Tennessee Department of Health was alerted by a clinician regarding a patient with culture-confirmed Aspergillus fumigatus meningitis diagnosed 46 days after epidural steroid injection at a Tennessee ambulatory surgical center. By September 27, the initial investigation, carried out by the Tennessee Department of Health in collaboration with CDC and the North Carolina Department of Health and Human Services, had identified an additional eight patients with clinically diagnosed, culture-negative meningitis: seven in Tennessee and one in North Carolina. All nine patients had received epidural steroid injection with preservative-free methylprednisolone acetate solution (MPA), compounded at New England Compounding Center (NECC) in Framingham, Massachusetts. All nine patients had received one or more injections from three lots of MPA (lot numbers 05212012@68; 06292012@26; and 08102012@51). As of October 10, a multistate investigation led by CDC in collaboration with state and local health departments and the Food and Drug Administration (FDA) had identified 137 cases and 12 deaths associated with this outbreak in 10 states. Active case-finding efforts and extensive investigation into medications and medication lot numbers received by patients have confirmed that, as of October 10, no cases were associated with other lots of MPA, nor were any associated with other NECC products. This report describes the ongoing investigation by CDC and state and local health departments, and includes important recommendations for physicians and patients.

  14. Solution-processed nanocomposites containing molybdenum oxide and gold nanoparticles as anode buffer layers in plasmonic-enhanced organic photovoltaic devices.

    PubMed

    Tan, Kim-Shih; Chuang, Ming-Kai; Chen, Fang-Chung; Hsu, Chain-Shu

    2013-12-11

    Solution-processed nanocomposites containing molybdenum oxide (MoO3) and gold nanoparticles (Au NPs) have been used as anode buffer layers in organic photovoltaic devices (OPVs). The resulting devices exhibit a remarkable enhancement in power conversion efficiency after Au NPs were incorporated into the device. Such enhancements can be attributed to the localized surface plasmon resonance induced by the metallic nanostructures. We have also found that the rate of exciton generation and the probability of exciton dissociation were increased. Furthermore, the devices made of the MoO3 buffer layer containing Au NPs exhibited superior stability. This work opens up the possibility of fabricating OPVs with both high efficiency and a prolonged lifetime.

  15. Mechanism of enhanced antibacterial activity of ultra-fine ZnO in phosphate buffer solution with various organic acids.

    PubMed

    Yang, Lin; Kuang, Huijuan; Liu, Yingxia; Xu, Hengyi; Aguilar, Zoraida P; Xiong, Yonghua; Wei, Hua

    2016-11-01

    Ultra-fine-ZnO showed low toxicity in complex water matrix containing multiple components such as PBS buffer and the toxic mechanism of ultra-fine-ZnO has not been clearly elucidated. In present study, enhanced antibacterial activity of 200 nm diameter ultra-fine-ZnO in PBS buffer against Bacillus cereus and Escherichia coli were observed in the presence of several organic acids in comparison with ultra-fine-ZnO in PBS buffer alone. These findings indicated that the toxic effects of the ultra-fine-ZnO was dependent on the concentration of released Zn(2+) which was affected by organic acids. The production of reactive oxygen species (ROS) did not responsible to the toxic mechanism of ultra-fine-ZnO which was tested using the antioxidant N-Acetylcysteine (NAC). Indeed, ultra-fine-ZnO induced bacteria cell membrane leakages and cell morphology damages that eventually led to cell death, which were confirmed using propidium monoazide (PMA) in combination with PCR and scanning electron microscopy (SEM). All data gathered herein suggested that released Zn(2+) played a major role in the microbial toxicity of ultra-fine-ZnO.

  16. Development of a single-run analytical method for the detection of ten multiclass emerging contaminants in agricultural soil using an acetate-buffered QuEChERS method coupled with LC-MS/MS.

    PubMed

    Lee, Young-Jun; Choi, Jeong-Heui; Abd El-Aty, A M; Chung, Hyung Suk; Lee, Han Sol; Kim, Sung-Woo; Rahman, Md Musfiqur; Park, Byung-Jun; Kim, Jang-Eok; Shin, Ho-Chul; Shim, Jae-Han

    2017-01-01

    This study was undertaken to develop and validate a single multiresidue method for the monitoring of ten multiclass emerging contaminants, viz. ceftiofur, clopidol, florfenicol, monensin, salinomycin, sulfamethazine, sulfathiazole, sulfamethoxazole, tiamulin, and tylosin in agricultural soil. Samples were extracted using an acetate-buffered, modified quick, easy, cheap, effective, rugged, and safe method followed by liquid chromatography with tandem mass spectrometric analysis in positive ion mode. Separation on an Eclipse Plus C18 column was conducted in gradient elution mode using a mobile phase of methanol (A) and distilled water (B), each containing 0.1% formic acid and 5 mM ammonium formate. The linearity of the matrix-matched calibrations, expressed as determination coefficients, was good, with R(2) ≥ 0.9908. The limits of quantification were in the range 0.05-10 μg/kg. Blank soil samples spiked with 4 × and 20 × the limit of quantification provided recovery rates of 60.2-120.3% (except sulfamethoxazole spiked at 4 × the limit of quantification, which gave 131.9%) with a relative standard deviation < 13% (except clopidol spiked at 20 × the limit of quantification, which gave 25.2%). This method was successfully applied to the monitoring of 51 field-incurred agricultural loamy-sand soil samples collected from 17 provincial areas throughout the Korean Peninsula. The detected and quantified drugs were clopidol (≤ 4.8 μg/kg), sulfathiazole (≤ 7.7 μg/kg), sulfamethazine (≤ 6.6 μg/kg), tiamulin (≤ 10.0 μg/kg), and tylosin (≤ 5.3 μg/kg). The developed method is simple and versatile, and can be used to monitor various classes of veterinary drugs in soil.

  17. 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.

  18. Corrosion behavior of Mg-3Zn/bioglass (45S5) composite in simulated body fluid (SBF) and phosphate buffered saline (PBS) solution

    NASA Astrophysics Data System (ADS)

    Ab llah, N.; Jamaludin, S. B.; Daud, Z. C.; Zaludin, M. A. F.; Jamal, Z. A. Z.; Idris, M. S.; Osman, R. A. M.

    2016-07-01

    Magnesium has emerged as promising materials in biomaterials research due to its good mechanical and physical properties closer to human bones. However, magnesium has poor corrosion resistance to chloride ions that exist in human blood plasma thus preventing its application in biomedical. The addition of zinc and bioglass can reduce magnesium corrosion rate. In this work, the effect of different solution media (Simulated Body Fluid and Phosphate Buffered Saline) to the corrosion behavior of Mg-Zn/bioglass (45S5) composites was investigated. The composites of Mg-3Zn added with 5, 10, 15, 20, 15 and 30 wt. % bioglass were fabricated by powder metallurgy. The composites were prepared by mixing at 140 rpm for 1 hour, pressing at 500 MPa and sintering in an argon environment at a temperature of 450°C for 3 hours. Sintered samples were immersed in Simulated Body Fluid (SBF) and Phosphate Buffered Saline (PBS) in order to investigate the corrosion behavior. Samples mass loss was determined after 3 days of immersion. Samples microstructure and corrosion products were analyzed using optical microscope and x-ray diffraction (XRD) respectively. The results revealed that the samples immersed in the Phosphate Buffered Saline (PBS) shows lower mass loss compare to the samples immersed in the Simulated Body Fluid (SBF) for all composition except for Mg-3Zn without bio-glass. The results indicated that the existence of high phosphate ions in PBS has retarded the corrosion rate of composite Mg-3Zn/45S5. The pH value of the PBS solution after immersion showed significant increase between 10.3 and 11.09. Diffraction pattern (XRD) showed the presence of Mg(OH)2 as the major corrosion product for samples immersed in the SBF and PBS solutions. The mass loss of samples decreased with the addition of bio-glass.

  19. Optimization of the Energy Level Alignment between the Photoactive Layer and the Cathode Contact Utilizing Solution-Processed Hafnium Acetylacetonate as Buffer Layer for Efficient Polymer Solar Cells.

    PubMed

    Yu, Lu; Li, Qiuxiang; Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Wang, Fuzhi; Zhang, Bing; Dai, Songyuan; Lin, Jun; Tan, Zhan'ao

    2016-01-13

    The insertion of an appropriate interfacial buffer layer between the photoactive layer and the contact electrodes makes a great impact on the performance of polymer solar cells (PSCs). Ideal interfacial buffer layers could minimize the interfacial traps and the interfacial barriers caused by the incompatibility between the photoactive layer and the electrodes. In this work, we utilized solution-processed hafnium(IV) acetylacetonate (Hf(acac)4) as an effective cathode buffer layer (CBL) in PSCs to optimize the energy level alignment between the photoactive layer and the cathode contact, with the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) all simultaneously improved with Hf(acac)4 CBL, leading to enhanced power conversion efficiencies (PCEs). Ultraviolet photoemission spectroscopy (UPS) and scanning Kelvin probe microscopy (SKPM) were performed to confirm that the interfacial dipoles were formed with the same orientation direction as the built-in potential between the photoactive layer and Hf(acac)4 CBL, benefiting the exciton separation and electron transport/extraction. In addition, the optical characteristics and surface morphology of the Hf(acac)4 CBL were also investigated.

  20. Thermal and Environmental Stability of Semi-Transparent Perovskite Solar Cells for Tandems Enabled by a Solution-Processed Nanoparticle Buffer Layer and Sputtered ITO Electrode.

    PubMed

    Bush, Kevin A; Bailie, Colin D; Chen, Ye; Bowring, Andrea R; Wang, Wei; Ma, Wen; Leijtens, Tomas; Moghadam, Farhad; McGehee, Michael D

    2016-05-01

    A sputtered oxide layer enabled by a solution-processed oxide nanoparticle buffer layer to protect underlying layers is used to make semi-transparent perovskite solar cells. Single-junction semi-transparent cells are 12.3% efficient, and mechanically stacked tandems on silicon solar cells are 18.0% efficient. The semi-transparent perovskite solar cell has a T 80 lifetime of 124 h when operated at the maximum power point at 100 °C without additional sealing in ambient atmosphere under visible illumination.

  1. Current characteristics of λ-DNA molecules/polystyrene nanoparticles in TBE buffer solution through micro/nanofluidic capillaries under DC electric field

    NASA Astrophysics Data System (ADS)

    Duan, Yifei; Zhao, Wei; Xue, Jing; Sun, Dan; Wang, Kaige; Wang, Guiren; Li, Junjie; Bai, Jintao; Gu, Changzhi

    2017-03-01

    In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate single bio-molecules and analyze their characteristics. To accurately and flexibly control the movement of single-molecule within micro/nanofluidic channels which are the basic components of Lab-chips, the current signals in micro/nanocapillaries filled with solutions of DNA molecules or polystyrene (PS) nanoparticles are systematically studied. Experimental results indicate that the current response along the micro/nanocapillaries can be significantly influenced by the diameter of the capillaries and the pH value of the solutions. Specifically, when there is only a pure (TBE) solution, the electric conductance does not monotonically decrease with decreasing the diameter of the capillaries, but slightly increases with decreasing the capillary diameter. When λ-DNA molecules or PS nanoparticles are added into the TBE buffer, the size effect on the electric conductance of the solutions are quite different. Although in the former, the electric conductance behaves differently from that in the pure TBE solution and decreases with the decreasing diameter, in the latter, the change is similar to that in the pure TBE solution. Besides, an abnormal ‘falling’ of the electric conductance is observed in a capillary with diameter of 200 nm. The investigation will significantly enhance the understanding on the electric properties of the solutions of biomolecules and particles in micro/nanofluidics. This is especially helpful for designing functional Lab-chip devices.

  2. Activity of the Human Rhinovirus 3C Protease Studied in Various Buffers, Additives and Detergents Solutions for Recombinant Protein Production

    PubMed Central

    Tufail, Soban; Ismat, Fouzia; Imran, Muhammad; Iqbal, Mazhar; Mirza, Osman; Rhaman, Moazur

    2016-01-01

    Proteases are widely used to remove affinity and solubility tags from recombinant proteins to avoid potential interference of these tags with the structure and function of the fusion partner. In recent years, great interest has been seen in use of the human rhinovirus 3C protease owing to its stringent sequence specificity and enhanced activity. Like other proteases, activity of the human rhinovirus 3C protease can be affected in part by the buffer components and additives that are generally employed for purification and stabilization of proteins, hence, necessitate their removal by tedious and time-consuming procedures before proteolysis can occur. To address this issue, we examined the effect of elution buffers used for common affinity based purifications, salt ions, stability/solubility and reducing agents, and detergents on the activity of the human rhinovirus 3C protease using three different fusion proteins at 4°C, a temperature of choice for purification of many proteins. The results show that the human rhinovirus 3C protease performs better at 4°C than the frequently used tobacco etch virus protease and its activity was insensitive to most of the experimental conditions tested. Though number of fusion proteins tested is limited, we expect that these finding will facilitate the use of the human rhinovirus 3C protease in recombinant protein production for pharmaceutical and biotechnological applications. PMID:27093053

  3. Activity of the Human Rhinovirus 3C Protease Studied in Various Buffers, Additives and Detergents Solutions for Recombinant Protein Production.

    PubMed

    Ullah, Raheem; Shah, Majid Ali; Tufail, Soban; Ismat, Fouzia; Imran, Muhammad; Iqbal, Mazhar; Mirza, Osman; Rhaman, Moazur

    2016-01-01

    Proteases are widely used to remove affinity and solubility tags from recombinant proteins to avoid potential interference of these tags with the structure and function of the fusion partner. In recent years, great interest has been seen in use of the human rhinovirus 3C protease owing to its stringent sequence specificity and enhanced activity. Like other proteases, activity of the human rhinovirus 3C protease can be affected in part by the buffer components and additives that are generally employed for purification and stabilization of proteins, hence, necessitate their removal by tedious and time-consuming procedures before proteolysis can occur. To address this issue, we examined the effect of elution buffers used for common affinity based purifications, salt ions, stability/solubility and reducing agents, and detergents on the activity of the human rhinovirus 3C protease using three different fusion proteins at 4°C, a temperature of choice for purification of many proteins. The results show that the human rhinovirus 3C protease performs better at 4°C than the frequently used tobacco etch virus protease and its activity was insensitive to most of the experimental conditions tested. Though number of fusion proteins tested is limited, we expect that these finding will facilitate the use of the human rhinovirus 3C protease in recombinant protein production for pharmaceutical and biotechnological applications.

  4. Regioselective organocatalysis: a theoretical prediction of the selective rate acceleration of the SN2 reaction between an acetate ion and primary alkyl chlorides in DMSO solution.

    PubMed

    Pliego, Josefredo R

    2006-05-07

    High level ab initio calculations, including the solvent effect through a continuum solvation model, predict that 1,4-benzenedimethanol is able to catalyse the S(N)2 reaction between an acetate ion and primary alkyl chlorides in dimethyl sulfoxide solution. The catalysis takes place through two selective hydrogen bonds to the transition state. However, for secondary alkyl chlorides the catalysis is not effective due to steric repulsion and desolvation. This effect induces regioselective control of S(N)2 esterification reactions.

  5. Real-time HD Exchange Kinetics of Proteins from Buffered Aqueous Solution with Electrothermal Supercharging and Top-Down Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Going, Catherine C.; Xia, Zijie; Williams, Evan R.

    2016-06-01

    Electrothermal supercharging (ETS) with electrospray ionization produces highly charged protein ions from buffered aqueous solutions in which proteins have native folded structures. ETS increases the charge of ribonuclease A by 34%, whereas only a 6% increase in charge occurs for a reduced-alkylated form of this protein, which is unfolded and its structure is ~66% random coil in this solution. These results indicate that protein denaturation that occurs in the ESI droplets is the primary mechanism for ETS. ETS does not affect the extent of solution-phase hydrogen-deuterium exchange (HDX) that occurs for four proteins that have significantly different structures in solution, consistent with a droplet lifetime that is considerably shorter than observable rates of HDX. Rate constants for HDX of ubiquitin are obtained with a spatial resolution of ~1.3 residues with ETS and electron transfer dissociation of the 10+ charge-state using a single capillary containing a few μL of protein solution in which HDX continuously occurs. HDX protection at individual residues with ETS HDX is similar to that with reagent supercharging HDX and with solution-phase NMR, indicating that the high spray potentials required to induce ETS do not lead to HD scrambling.

  6. Dynamics of Liquid Plugs of Buffer and Surfactant Solutions in a Micro-Engineered Pulmonary Airway Model

    PubMed Central

    Tavana, Hossein; Kuo, Chuan-Hsien; Lee, Qian Yi; Mosadegh, Bobak; Huh, Dongeun; Christensen, Paul J.; Grotberg, James B.; Takayama, Shuichi

    2009-01-01

    We describe a bio-inspired microfluidic system that resembles pulmonary airways and enables on-chip generation of airway occluding liquid plugs from a stratified air-liquid two-phase flow. User-defined changes in the air stream pressure facilitated by mechanical components and tuning the wettability of the microchannels enable generation of well-defined liquid plugs. Significant differences are observed in liquid plug generation and propagation when surfactant is added to the buffer. The plug flow patterns suggest a protective role of surfactant for airway epithelial cells against pathological flow-induced mechanical stresses. We discuss the implications of the findings for clinical settings. This approach and the described platform will enable systematic investigation of the effect of different degrees of fluid mechanical stresses on lung injury at the cellular level and administration of exogenous therapeutic surfactants. PMID:20017471

  7. Low-Temperature Solution-Processed SnO2 Nanoparticles as a Cathode Buffer Layer for Inverted Organic Solar Cells.

    PubMed

    Tran, Van-Huong; Ambade, Rohan B; Ambade, Swapnil B; Lee, Soo-Hyoung; Lee, In-Hwan

    2017-01-18

    SnO2 recently has attracted particular attention as a powerful buffer layer for organic optoelectronic devices due to its outstanding properties such as high electron mobility, suitable band alignment, and high optical transparency. Here, we report on facile low-temperature solution-processed SnO2 nanoparticles (NPs) in applications for a cathode buffer layer (CBL) of inverted organic solar cells (iOSCs). The conduction band energy of SnO2 NPs estimated by ultraviolet photoelectron spectroscopy was 4.01 eV, a salient feature that is necessary for an appropriate CBL. Using SnO2 NPs as CBL derived from a 0.1 M precursor concentration, P3HT:PC60BM-based iOSCs showed the best power conversion efficiency (PCE) of 2.9%. The iOSC devices using SnO2 NPs as CBL revealed excellent long-term device stabilities, and the PCE was retained at ∼95% of its initial value after 10 weeks in ambient air. These solution-processed SnO2 NPs are considered to be suitable for the low-cost, high throughput roll-to-roll process on a flexible substrate for optoelectronic devices.

  8. Natural dissolved organic matter mobilizes Cd but does not affect the Cd uptake by the green algae Pseudokirchneriella subcapitata (Korschikov) in resin buffered solutions.

    PubMed

    Verheyen, Liesbeth; Versieren, Liske; Smolders, Erik

    2014-09-01

    Natural dissolved organic matter (DOM) can have contrasting effects on metal bioaccumulation in algae because of complexation reactions that reduce free metal ion concentrations and because of DOM adsorption to algal surfaces which promote metal adsorption. This study was set up to reveal the role of different natural DOM samples on cadmium (Cd) uptake by the green algae Pseudokirchneriella subcapitata (Korschikov). Six different DOM samples were collected from natural freshwater systems and isolated by reverse osmosis. In addition, one (13)C enriched DOM sample was isolated from soil to trace DOM adsorption to algae. Algae were exposed to standardized solutions with or without these DOM samples, each exposed at equal DOM concentrations and at equal non-toxic Cd(2+) activity (∼4 nM) that was buffered with a resin. The DOM increased total dissolved Cd by factors 3-16 due to complexation reactions at equal Cd(2+) activity. In contrast, the Cd uptake was unaffected by DOM or increased maximally 1.6 fold ((13)C enriched DOM). The (13)C analysis revealed that maximally 6% of algal C was derived from DOM and that this can explain the small increase in biomass Cd. It is concluded that free Cd(2+) and not DOM-complexed Cd is the main bioavailable form of Cd when solution Cd(2+) is well buffered.

  9. Solute-solvent interactions in micellar electrokinetic chromatography. Selectivity of lithium dodecyl sulfate-lithium perfluorooctanesulfonate mixed-micellar buffers.

    PubMed

    Fuguet, E; Ràfols, C; Bosch, E; Rosés, M; Abraham, M H

    2001-01-12

    The solvation parameter model has been applied to the characterization of micellar electrokinetic chromatographic (MEKC) systems with mixtures of lithium dodecyl sulfate and lithium perfluorooctanesulfonate as surfactant. The variation in MEKC surfactant composition results in changes in the coefficients of the correlation equation, which in turns leads to information on solute-solvent and solute-micelle interactions. Lithium perfluorooctanesulfonate is more dipolar and hydrogen bond acidic but less polarizable and hydrogen bond basic than lithium dodecyl sulfate. Therefore mixtures of lithium dodecyl sulfate and lithium perfluorooctanesulfonate cover a very wide range of polarity and hydrogen bond properties, which in turn results in important selectivity changes for analytes with different solute properties.

  10. Environmental cadmium levels increase phytochelatin and glutathione in lettuce grown in a chelator-buffered nutrient solution.

    PubMed

    Maier, Elizabeth A; Matthews, Rosalyn D; McDowell, Jennifer A; Walden, Rebecca R; Ahner, Beth A

    2003-01-01

    Phytochelatins are enzymatically synthesized peptides involved in metal detoxification and have been measured in plants grown at very high Cd concentrations, but few studies have examined the response of plants at lower environmentally relevant Cd concentrations. Using an ethylenediaminetetraacetic acid (EDTA)-buffered nutrient medium, we have varied Cd exposure and measured phytochelatin and glutathione concentrations in romaine lettuce (Lactuca sativa L. var. longifolia Lam. var. Parris Island) grown in a flow-through hydroponic (FTH) system. Very low free ionic Cd (10(-9.6) M) increased average phytochelatin concentrations above those of controls, and increasing Cd resulted in increased phytochelatin production, though increases were tissue dependent. Glutathione concentrations also increased with increasing Cd. In other standard hydroponic experiments, the media were manipulated to vary total Cd concentration while the ionic Cd was fixed. We found that the total amount of Cd (primarily EDTA bound) in the medium altered thiol production in roots, whereas thiols in leaves remained constant. The Cd uptake into roots and translocation to old leaves was also influenced by the total concentration in the medium. Cadmium in all tissues was lower and in some tissues thiol concentrations were higher than in FTH-grown plants grown in identical medium, suggesting that nutrient delivery technique is also an important variable. Though phytochelatin and glutathione production can be sensitive to changes in bioavailable Cd, thiol concentrations will not necessarily reflect the Cd content of the plant tissues.

  11. Studies of the chemistry of the [Ru(H{sub 2}O)Cl{sub 5}]{sup 2{minus}} form of ruthenium(III) in acetic acid solutions

    SciTech Connect

    Buslaeva, T.M.; Rudnitskaya, O.V.; Marov, I.N.; Red`kina, S.N.; Belyaeva, V.K.

    1995-03-01

    The behavior of the [Ru(H{sub 2}O)Cl{sub 5}]{sup 2{minus}} form of ruthenium(III) in acetic acid solutions is studied for the first time. It is established that, when the solution of the title complex is allowed to stand in 8.5 M CH{sub 3}COOH at 50{degrees}C, it first hydrates with simultaneous substitution of the acetate ions for the water molecules to form the [Ru(H{sub 2}O)Cl{sub 4}(CH{sub 3}COO)]{sup 2{minus}} and/or [RuCl{sub 4}(CH{sub 3}COO){sub 2}]{sup 3{minus}} complexes in addition to [Ru(H{sub 2}O){sub 2}Cl{sub 4}]{sup {minus}}. The two former complexes yield EPR signals with 2.68 and 2.52 g-factors, respectively. It is noted that EPR spectra with g = 2.31, 2.21, 2.09, and 2.05 can belong both to the mono- and polynuclear ruthenium(III) compounds that are formed in reaction of the parent complex with acetic acid. Experimental evidence favoring both currently suggested concepts is presented.

  12. Solid phase extraction of proteins from buffer solutions employing capillary-channeled polymer (C-CP) fibers as the stationary phase.

    PubMed

    Burdette, Carolyn Q; Marcus, R Kenneth

    2013-02-21

    Polypropylene (PP) capillary-channeled polymer (C-CP) fibers are applied for solid phase extraction (SPE) of proteins from aqueous buffer solutions using a micropipette tip-based format. A process was developed in which centrifugation is used as the moving force for solution passage in the loading/washing steps instead of the previously employed manual aspiration. The complete procedure requires ~15 minutes, with the number of samples run in parallel limited only by the capacity of the centrifuge. The method performance was evaluated based on adsorption and elution characteristics of several proteins (cytochrome c, lysozyme, myoglobin, and glucose oxidase) from 150 mM phosphate buffered saline (PBS) solutions. Protein concentration ranges of ~2 to 100 μg mL(-1) were employed and the recovery characteristics determined through UV-Vis absorbance spectrophotometry for protein quantification. The protein loading capacities across the range of proteins was ~1.5 μg for the 5 mg fiber tips. Average recoveries from PBS were determined for each protein sample; cytochrome c ~86%, lysozyme ~80%, myoglobin ~86%, and glucose oxidase ~89%. Recoveries from more complex matrices, synthetic urine and synthetic saliva, were determined to be ~90%. A 10× dilution study for a fixed 1 μg protein application yielded 94 ± 3.2% recoveries. The C-CP tips provided significantly higher recoveries for myoglobin in a 150 mM PBS matrix in comparison to a commercially available protein SPE product, with the added advantages of low cost, rapid processing, and reusability.

  13. A controlled Nordic multicentre study of zuclopenthixol acetate in oil solution, haloperidol and zuclopenthixol in the treatment of acute psychosis.

    PubMed

    Baastrup, P C; Alhfors, U G; Bjerkenstedt, L; Dencker, S J; Fensbo, C; Gravem, A; Pedersen, V; Elgen, K; Brekke, B; Fredslund-Andersen, K

    1993-01-01

    Zuclopenthixol acetate--a new injectable formulation with a duration of action of 2-3 days--was compared with conventional intramuscular and oral formulations of haloperidol and zuclopenthixol in the initial treatment of acutely disturbed, psychotic patients. The patients were stratified into 3 diagnostic categories: acute psychoses (48 patients), mania (22 patients), and exacerbation of chronic psychoses (73 patients). The patients were rated on the Brief Psychiatric Rating Scale (BPRS), the Bech-Rafaelsen Mania Rating Scale (BRMAS) (only manic patients) and globally on the Clinical Global Impression (CGI). The study was an open, randomized multicentre trial with a 6-day treatment period. The zuclopenthixol acetate patients received 1-4 doses, the haloperidol patients 1-26 and the zuclopenthixol patients 1-22 doses. The assessments on the CGI showed that all 3 treatments caused a clear reduction of the severity of illness scores in all 3 diagnostic categories, with no differences between treatments. The ratings of the acute and chronic psychotic patients on the BPRS also showed significant reductions in scores with no differences between treatments. All 3 treatments caused a rapid remission of symptoms on the BRMAS. Haloperidol induced hypokinesia in significantly more patients than zuclopenthixol acetate after 24 h. Later there were no significant differences between treatments. Zuclopenthixol acetate fulfils many desires for an amended neuroleptic formulation for the initial treatment of acutely disturbed psychotic patients.

  14. 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)

  15. In-Line Desalting of Proteins from Buffer and Synthetic Urine Solution Prior to ESI-MS Analysis via a Capillary-Channeled Polymer Fiber Microcolumn

    NASA Astrophysics Data System (ADS)

    Burdette, Carolyn Q.; Marcus, R. Kenneth

    2013-06-01

    Presented here is a novel in-line solid phase extraction (SPE) method utilizing a capillary-channeled polymer (C-CP) fiber microcolumn prior to introduction to an electrospray ionization (ESI) source. The high permeability of the microcolumn allows for operation under syringe pump or HPLC driven flow, ultimately providing greater mass spectral clarity and accurate molecular weight determinations for different protein/buffer combinations. Studies presented here focus on the desalting of several target proteins from a standard phosphate buffered saline (PBS) matrix and a synthetic urine solution prior to ESI-MS determinations. In every case, responses for μM-level proteins in PBS improve from the situation of not permitting molecular weight determinations to values that are precise to better than ±10 Da, without internal standards, with relative improvements in the signal-to-background ratios (S/B) on the order of 3,000×. De-salting of a myoglobin-spiked (12 μM) synthetic urine results in equally-improved spectral quality.

  16. The use of ethylene glycol solution as the running buffer for highly efficient microchip-based electrophoresis in unmodified cyclic olefin copolymer microchips.

    PubMed

    Wang, Qin; Zhang, Yuan; Ding, Hui; Wu, Jing; Wang, Lili; Zhou, Lei; Pu, Qiaosheng

    2011-12-30

    An ethylene glycol solution was used as the electrophoretic running buffer in unmodified cyclic olefin copolymer (COC) microchips to minimize the interactions between the analytes and the hydrophobic walls of the plastic microchannels, enhance the resolution of the analytes and eliminate the uncontrollable dispersion caused by uneven liquid levels and non-uniform surfaces of the separation channels. Five amino acids that were labeled with fluorescein isothiocyanate (FITC) were used as model analytes to examine the separation efficiency. The effects of ethylene glycol concentration, pH and sodium tetraborate concentration were systematically investigated. The five FITC-labeled amino acids were effectively resolved using a COC microchip with an effective length of 2.5 cm under optimum conditions, which included using a running buffer of 20 mmol/L sodium tetraborate in ethylene glycol:water (80:20, v/v), pH 6.7. A theoretical plate number of 4.8 × 10(5)/m was obtained for aspartic acid. The system exhibited good repeatability, and the relative standard deviations (n=5) of the peak areas and migration times were no more than 3.4% and 0.7%, respectively. Furthermore, the system was successfully applied to elucidate these five amino acids in human saliva.

  17. 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.

  18. Flecainide acetate acetic acid solvates.

    PubMed

    Veldre, Kaspars; Actiņs, Andris; Eglite, Zane

    2011-02-01

    Flecainide acetate forms acetic acid solvates with 0.5 and 2 acetic acid molecules. Powder X-ray diffraction, differential thermal analysis/thermogravimetric, infrared, and potentiometric titration were used to determine the composition of solvates. Flecainide acetate hemisolvate with acetic acid decomposes to form a new crystalline form of flecainide acetate. This form is less stable than the already known polymorphic form at all temperatures, and it is formed due to kinetic reasons. Both flecainide acetate nonsolvated and flecainide acetate hemisolvate forms crystallize in monoclinic crystals, but flecainide triacetate forms triclinic crystals. Solvate formation was not observed when flecainide base was treated with formic acid, propanoic acid, and butanoic acid. Only nonsolvated flecainide salts were obtained in these experiments.

  19. Acute intradialytic cardiac function and inflammatory cytokine changes during high-efficiency online hemodiafiltration with acetate-free and standard dialysis solutions.

    PubMed

    Tiranathanagul, Khajohn; Tangvoraphonkchai, Kamonwan; Srisawat, Nattachai; Susantitaphong, Paweena; Tungsanga, Kriang; Praditpornsilpa, Kearkiat; Eiam-Ong, Somchai

    2015-06-01

    Acetate in standard acetate-containing bicarbonate (AC) dialysis fluid could induce peripheral vasodilatation, suppression of myocardial function, and inflammatory cytokine production, resulting in intradialytic hypotension in conventional hemodialysis (HD) patients. Online hemodiafiltration (HDF) provides superior hemodynamic stability over HD. The potentially additive hemodynamic benefits of the novel acetate-free bicarbonate (AF) dialysis fluid in online HDF have never been explored before. The present randomized, double-blind, crossover study was conducted in 22 online HDF patients to investigate the impact of AF dialysis fluid on hemodynamic and cytokine changes compared with AC dialysis fluid in online HDF. The results demonstrated the comparable changes of arterial pressure between AF and AC online HDF. During the study periods, the incidences of composite intradialytic hypotension and other adverse events were not different. The baseline and hourly changes of cardiac index, cardiac output, and peripheral vascular resistance during dialysis were comparable (P=0.534, 0.199, and 0.641, respectively). The percent reductions of NT-proBNP and cTnT were not significantly different (72.6 ± 12.3 vs. 72.6 ± 12.8%, P=0.99 and 35.2 ± 12.8 vs. 36.7 ± 12.0%, P=0.51). The changes of all pro-inflammatory cytokines (IL-2β, IL-6, IL-8, and TNF-α) and anti-inflammatory cytokine (IL-10) during dialysis were comparable between both groups. In conclusion, AF dialysis solution does not offer additional hemodynamic benefit for stable online HDF patients. The hemodynamic stability provided by online HDF might protect the adverse effects of acetate.

  20. Buffer Effects in the Solubility, Nucleation and Growth of Chicken Egg White Lysozyme

    NASA Technical Reports Server (NTRS)

    Gibson, Ursula J.

    1999-01-01

    The growth of protein crystals is important for determination of their three-dimensional structure, which relates to their biochemical functions and to the practical goal of designing pharmaceuticals to modify that function. While many proteins have been successfully crystallized by a variety of methods, there is still limited understanding of the process of nucleation and growth of even the simplest proteins. Chicken egg-white lysozyme (CEWL) is readily crystallized under a variety of conditions, and studies underway at MSFC are designed to elucidate the mechanisms by which the crystals nucleate and grow. We have investigated the effect of buffer choice on the solubility, nucleation and growth of CEWL. CEWL was purified by dialysis against a .05M phosphate buffer and chromatographic separation from contaminants in a sepharose column. Solubility studies were made as a function of buffer concentration for phosphate and formate buffers, and the nucleation and growth of crystals at 10 C was studied as a function of pH for oxalate, succinate, formate, butyrate, carbonate, phosphate and acetate buffer solutions. The solubility data support the conclusion that there is a solubility minimum as a function of buffer concentration for amphiphilic molecules, while no minimum is observed for a phosphate buffer. Nucleation is suppressed at pH greater than pKa for all buffers except phosphate. The aspect ratio of the (110) faces is shown to be a function of crystal size, rather than pH.

  1. CdS and Cd-Free Buffer Layers on Solution Phase Grown Cu2ZnSn(SxSe1- x)4 :Band Alignments and Electronic Structure Determined with Femtosecond Ultraviolet Photoemission Spectroscopy

    SciTech Connect

    Haight, Richard; Barkhouse, Aaron; Wang, Wei; Yu, Luo; Shao, Xiaoyan; Mitzi, David; Hiroi, Homare; Sugimoto, Hiroki

    2013-12-02

    The heterojunctions formed between solution phase grown Cu2ZnSn(SxSe1- x)4(CZTS,Se) and a number of important buffer materials including CdS, ZnS, ZnO, and In2S3, were studied using femtosecond ultraviolet photoemission spectroscopy (fs-UPS) and photovoltage spectroscopy. With this approach we extract the magnitude and direction of the CZTS,Se band bending, locate the Fermi level within the band gaps of absorber and buffer and measure the absorber/buffer band offsets under flatband conditions. We will also discuss two-color pump/probe experiments in which the band bending in the buffer layer can be independently determined. Finally, studies of the bare CZTS,Se surface will be discussed including our observation of mid-gap Fermi level pinning and its relation to Voc limitations and bulk defects.

  2. Direct Measurement of 59Fe-Labeled Fe2+ Influx in Roots of Pea Using a Chelator Buffer System to Control Free Fe2+ in Solution.

    PubMed Central

    Fox, T. C.; Shaff, J. E.; Grusak, M. A.; Norvell, W. A.; Chen, Y.; Chaney, R. L.; Kochian, L. V.

    1996-01-01

    Fe2+ transport in plants has been difficult to quantify because of the inability to control Fe2+ activity in aerated solutions and non-specific binding of Fe to cell walls. In this study, a Fe(II)-3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-4[prime]4"-disulfonic acid buffer system was used to control free Fe2+ in uptake solutions. Additionally, desorption methodologies were developed to adequately remove nonspecifically bound Fe from the root apoplasm. This enabled us to quantify unidirectional Fe2+ influx via radiotracer (59Fe) uptake in roots of pea (Pisum sativum cv Sparkle) and its single gene mutant brz, an Fe hyperaccumulator. Fe influx into roots was dramatically inhibited by low temperature, indicating that the measured Fe accumulation in these roots was due to true influx across the plasma membrane rather than nonspecific binding to the root apoplasm. Both Fe2+ influx and Fe translocation to the shoots were stimulated by Fe deficiency in Sparkle. Additionally, brz, a mutant that constitutively exhibits high ferric reductase activity, exhibited higher Fe2+ influx rates than +Fe-grown Sparkle. These results suggest that either Fe deficiency triggers the induction of the Fe2+ transporter or that the enhanced ferric reductase activity somehow stimulates the activity of the existing Fe2+ transport protein. PMID:12226276

  3. Quantitative structure-property relationship modeling of water-to-wet butyl acetate partition coefficient of 76 organic solutes using multiple linear regression and artificial neural network.

    PubMed

    Dashtbozorgi, Zahra; Golmohammadi, Hassan

    2010-12-01

    The main aim of this study was the development of a quantitative structure-property relationship method using an artificial neural network (ANN) for predicting the water-to-wet butyl acetate partition coefficients of organic solutes. As a first step, a genetic algorithm-multiple linear regression model was developed; the descriptors appearing in this model were considered as inputs for the ANN. These descriptors are principal moment of inertia C (I(C)), area-weighted surface charge of hydrogen-bonding donor atoms (HACA-2), Kier and Hall index (order 2) ((2)χ), Balaban index (J), minimum bond order of a C atom (P(C)) and relative negative-charged SA (RNCS). Then a 6-4-1 neural network was generated for the prediction of water-to-wet butyl acetate partition coefficients of 76 organic solutes. By comparing the results obtained from multiple linear regression and ANN models, it can be seen that statistical parameters (Fisher ratio, correlation coefficient and standard error) of the ANN model are better than that regression model, which indicates that nonlinear model can simulate the relationship between the structural descriptors and the partition coefficients of the investigated molecules more accurately.

  4. Extraction of formic and acetic acids from aqueous solution by dynamic headspace-needle trap extraction temperature and pH optimization.

    PubMed

    Lou, Da-Wei; Lee, Xinqing; Pawliszyn, Janusz

    2008-08-08

    A combined method of dynamic headspace-needle trap sample preparation and gas chromatography for the determination of formic and acetic acids in aqueous solution was developed in this study. A needle extraction device coupled with a gas aspirating pump was intended to perform sampling and preconcentration of target compounds from aqueous sample before gas chromatographic analysis. The needle trap extraction (NTE) technique allows for the successful sampling of short chain fatty acids under dynamic conditions while keeping the headspace (HS) volume constant. Two important parameters, including extraction temperature and effect of acidification, have been optimized and evaluated using the needle trap device. The method detection limits for the compounds estimated were 87.2microg/L for acetic acid and 234.8microg/L for formic acid in spite of the low flame ionization detection response for formic acid and its low Henry's law constant in aqueous solution. Precision was determined based on the two real samples and ranged between 4.7 and 10.7%. The validated headspace-needle trap extraction method was also successfully applied to several environmental samples.

  5. Formation of Amino Acids on the Sonolysis of Aqueous Solutions Containing Acetic Acid, Methane, or Carbon Dioxide, in the Presence of Nitrogen Gas.

    PubMed

    Dharmarathne, Leena; Grieser, Franz

    2016-01-21

    The sonolysis of aqueous solutions containing acetic acid, methane, or carbon dioxide in the presence of nitrogen gas was found to produce a number of different amino acids at a rate of ∼1 to 100 nM/min, using ultrasound at an operating power of 70 W and 355 kHz. Gas-phase elementary reactions are suggested, and discussed, to account for the formation of the complex biomolecules from the low molar mass solutes used. On the basis of the results, a new hypothesis is presented to explain the formation of amino acids under primitive atmospheric conditions and how their formation may be linked to the eventual abiotic genesis of life on Earth.

  6. Mesoxalaldehyde acetals

    SciTech Connect

    Gordeeva, G.N.; Kalashnikov, S.M.; Popov, Yu.N.; Kruglov, E.A.; Imashev, U.B.

    1987-11-10

    The treatment of methylglyoxal acetals by alkyl nitrites in the presence of the corresponding aliphatic alcohols and hydrochloric acid leads to the formation of linear mesoxalaldehyde acetals, whose structure was established by NMR spectroscopy and mass spectrometry. The major pathways for the decomposition of these molecules upon electron impact were established.

  7. Kinetic buffers.

    PubMed

    Alibrandi, Giuseppe; Fabbrizzi, Luigi; Licchelli, Maurizio; Puglisi, Antonio

    2015-01-12

    This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment.

  8. Role of Buffers in Protein Formulations.

    PubMed

    Zbacnik, Teddy J; Holcomb, Ryan E; Katayama, Derrick S; Murphy, Brian M; Payne, Robert W; Coccaro, Richard C; Evans, Gabriel J; Matsuura, James E; Henry, Charles S; Manning, Mark Cornell

    2017-03-01

    Buffers comprise an integral component of protein formulations. Not only do they function to regulate shifts in pH, they also can stabilize proteins by a variety of mechanisms. The ability of buffers to stabilize therapeutic proteins whether in liquid formulations, frozen solutions, or the solid state is highlighted in this review. Addition of buffers can result in increased conformational stability of proteins, whether by ligand binding or by an excluded solute mechanism. In addition, they can alter the colloidal stability of proteins and modulate interfacial damage. Buffers can also lead to destabilization of proteins, and the stability of buffers themselves is presented. Furthermore, the potential safety and toxicity issues of buffers are discussed, with a special emphasis on the influence of buffers on the perceived pain upon injection. Finally, the interaction of buffers with other excipients is examined.

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

    PubMed

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

    2007-04-02

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

  10. Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with (pyrazol-1-yl)acetic acid.

    PubMed

    Chen, Xiao-Yan; Goff, George S; Scott, Brian L; Janicke, Michael T; Runde, Wolfgang

    2013-03-18

    As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-1-yl)acetic acid (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-elements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = 5 and synthesized four lanthanide complexes of general formula [Ln(L)3(H2O)2]·nH2O (1, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = 1). All complexes were characterized by single crystal X-ray diffraction analysis revealing one-dimensional chain formations. Two distinct crystallographic structures are governed by the different coordination modes of carboxylate groups in L: terminal bidentate and bridging tridentate (1-3); terminal bidentate, bridging bidentate, and tridentate coordination in 4. Comparison of the solid state UV-vis-NIR diffuse reflectance spectra with solution state UV-vis-NIR spectra suggests a different species in solution and solid state. The different coordination in solid state and solution was verified by distinctive (13)C NMR signals of the carboxylate groups in the solid state NMR.

  11. An experimental study of zinc chloride speciation from 300 to 600 °C and 0.5 to 2.0 kbar in buffered hydrothermal solutions

    USGS Publications Warehouse

    Cygan, G.L.; Hemley, J.J.; d'Angelo, W. M.

    1994-01-01

    The solubility of sphalerite (ZnS) was measured in KCl-HCl-H2O solutions at 300-600??C and 0.5-2.0 kbar. The silicate assemblage K-feldspar-muscovite (or andalusite)-quartz was used to buffer the solution to acid conditions, resulting in the total solubility reaction 2K+ + KAl2AlSi3O10(OH)2 + 6SiO2 + ZnS + nCl- = ZnCln(2-n) + 3KAlSi3O8 + H2S. (muscovite) (quartz) (sphalerite) (K-feldspar) A computer retrieval technique was used to derive average chloride ligand numbers for chlorozinc species at 0.25-2.0 molal total chloride. This technique mathematically solves for the average ligand number using a series of pertinent chemical relations at P and T. Mono- and di-chlorozinc species were found to predominate throughout the pressure-temperature-composition range investigated. The logarithms of the first and second dissociation constants for ZnCl20 were evaluated over the P-T range; for example, at 1 kbar, the values -0.41 and -1.42 were computed for the logarithm of the first dissociation constant, while -7.62 and -10.57 were computed for the logarithm of the second dissociation constant, for 400 and 500??C, respectively. Results are compared to past studies conducted at subcritical conditions and differ in that we find no evidence for more highly coordinated chloro-zinc species except possibly for ZnCl3- at 600??C, 1 and 2 kbar. Our results are consistent with electrostatic theory, which favors lower charged to neutral molecules in low dielectric-constant media. ?? 1994.

  12. Morphological and phase evolution of TiO{sub 2} nanocrystals prepared from peroxotitanate complex aqueous solution: Influence of acetic acid

    SciTech Connect

    Chang, Jeong Ah; Vithal, Muga; Baek, In Chan; Seok, Sang Il

    2009-04-15

    Nanosized anatase and rutile TiO{sub 2} having different shape, phase and size have been prepared from aqueous solutions of peroxo titanium complex starting from titanium(IV) isopropoxide (TTIP), acetic acid and hydrogen peroxide (H{sub 2}O{sub 2}) in water/isopropanol media by a facile sol-gel process. The TiO{sub 2} nanocrystals are characterized by powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, TEM, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques. The influence of pH and the sequence of addition of reaction contents on the phase and morphology of TiO{sub 2} are studied. The reasons for the observation of only anatase and/or mixture of anatase and rutile are given. - Graphical abstract: The morphology of TiO{sub 2} depends on the sequence of addition of AcOH and H{sub 2}O{sub 2} from the system of titanium isopropoxide and acetic acid (AcOH) in the presence of H{sub 2}O{sub 2}.

  13. Solubility and speciation of atmospheric iron in buffer systems simulating cloud conditions

    NASA Astrophysics Data System (ADS)

    Upadhyay, Nabin; Majestic, Brian J.; Herckes, Pierre

    2011-04-01

    The solubility of iron (Fe) in atmospheric particulate matter (PM) is important to understand its chemistry and potential bioavailability to ocean phytoplankton. However, current studies on Fe solubility and its speciation are highly uncertain partly due to inconsistencies in analytical protocols. In this study, cloud-processing of atmospheric PM was simulated in acetate, formate, and oxalate buffers (pH = 4.30 ± 0.05) at 0.5, 1, 5, and 20 mM. Colorimetric analysis of Fe(II)-ferrozine complex showed that Fe solubility increased by an order of magnitude when acetate and formate concentrations increased from 0.5 mM to 5 mM, with a higher fraction of soluble Fe in acetate than in formate at lower buffer concentration (0.5 mM). Measured pH of sample extracts revealed that weak buffers are unable to maintain pH, presumably due to acidic or alkaline components of PM, requiring an optimum concentration (5 mM in this study) of acetate and formate for Fe solubility measurements. Similar extraction procedures revealed that oxalate buffer inhibits the formation of Fe(II)-ferrozine complex, especially with Fe(III)-containing solutions, rendering it unsuitable for Fe solubility measurements by Ferrozine method. Application of the optimized analytical method to PM samples from different environments showed quite variable Fe solubility, with the lowest (<1%) in dust-impacted samples and the highest (5%) in urban samples. The highest solubility (6.8%) was observed in ambient PM2.5 samples influenced by anthropogenic sources (car emissions) with more than 90% of soluble Fe in the form of Fe(II). Results from this study highlight the importance of the type and strength of buffer at a given pH for Fe solubility and provide further evidence of a higher Fe solubility in urban PM samples compared to desert dust.

  14. Development of a four-zone carousel process packed with metal ion-imprinted polymer for continuous separation of copper ions from manganese ions, cobalt ions, and the constituent metal ions of the buffer solution used as eluent.

    PubMed

    Jo, Se-Hee; Park, Chanhun; Yi, Sung Chul; Kim, Dukjoon; Mun, Sungyong

    2011-08-19

    A three-zone carousel process, in which Cu(II)-imprinted polymer (Cu-MIP) and a buffer solution were employed as adsorbent and eluent respectively, has been developed previously for continuous separation of Cu²⁺ (product) from Mn²⁺ and Co²⁺ (impurities). Although this process was reported to be successful in the aforementioned separation task, the way of using a buffer solution as eluent made it inevitable that the product stream included the buffer-related metal ions (i.e., the constituent metal ions of the buffer solution) as well as copper ions. For a more perfect recovery of copper ions, it would be necessary to improve the previous carousel process such that it can remove the buffer-related metal ions from copper ions while maintaining the previous function of separating copper ions from the other 2 impure heavy-metal ions. This improvement was made in this study by proposing a four-zone carousel process based on the following strategy: (1) the addition of one more zone for performing the two-step re-equilibration tasks and (2) the use of water as the eluent of the washing step in the separation zone. The operating conditions of such a proposed process were determined on the basis of the data from a series of single-column experiments. Under the determined operating conditions, 3 runs of carousel experiments were carried out. The results of these experiments revealed that the feed-loading time was a key parameter affecting the performance of the proposed process. Consequently, the continuous separation of copper ions from both the impure heavy-metal ions and the buffer-related metal ions could be achieved with a purity of 91.9% and a yield of 92.8% by using the proposed carousel process based on a properly chosen feed-loading time.

  15. Cation-specific interactions with carboxylate in amino acid and acetate aqueous solutions: X-ray absorption and ab initio calculations.

    PubMed

    Aziz, Emad F; Ottosson, Niklas; Eisebitt, Stefan; Eberhardt, Wolfgang; Jagoda-Cwiklik, Barbara; Vácha, Robert; Jungwirth, Pavel; Winter, Bernd

    2008-10-09

    Relative interaction strengths between cations (X = Li (+), Na (+), K (+), NH 4 (+)) and anionic carboxylate groups of acetate and glycine in aqueous solution are determined. These model systems mimic ion pairing of biologically relevant cations with negatively charged groups at protein surfaces. With oxygen 1s X-ray absorption spectroscopy, we can distinguish between spectral contributions from H 2O and carboxylate, which allows us to probe the electronic structure changes of the atomic site of the carboxylate group being closest to the countercation. From the intensity variations of the COO (-) aq O 1s X-ray absorption peak, which quantitatively correlate with the change in the local partial density of states from the carboxylic site, interactions are found to decrease in the sequence Na (+) > Li (+) > K (+) > NH 4 (+). This ordering, as well as the observed bidental nature of the -COO (-) aq and X (+) aq interaction, is supported by combined ab initio and molecular dynamics calculations.

  16. Filtration through a polyester white cell-reduction filter of plasma-poor platelet concentrates prepared with an acetate-containing additive solution.

    PubMed

    Shimizu, T; Mizuno, S; Yamaguchi, H; Kamiya, T; Kokubo, Y

    1993-09-01

    It is of practical importance to known whether the adsorption of platelets and contaminating white cells (WBCs) by the WBC-reduction filter is altered when platelet concentrates (PCs) are prepared in a plasma-poor condition with an acetate-containing additive solution (Seto sol). Plasma-poor PCs with 11-percent residual plasma were prepared from apheresis platelet-rich plasma by using a sterile docking device with steam-sterilized Seto sol. Seto sol contains 115 mM (115 mmol/L) NaCl, 4 mM (4 mmol/L) KCl, 3 mM (3 mmol/L) MgCl2, 10 mM (10 mmol/L) Na3PO4, 15 mM (15 mmol/L) acetate, 3 mM (3 mmol/L) Na3 citrate, and 10 mM (10 mmol/L) glucose (pH 7.1). The solution was steam-sterilized under nitrogen gas. On Days 1 and 5, pooled Seto sol PCs (2.4 x 10(11) platelets) were filtered with a polyester filter at a flow rate of 10 mL per minute. The WBC-removal rate was over 99.9 percent with a platelet recovery of 88 percent following Day 1 filtration. These values were very similar to those of plasma PCs, and 84-percent recovery was achieved following Day 5 filtration. However, when 1 unit of Seto sol PCs with half the number of platelets was filtered with the polyester filter, platelet recovery was about 16 to 17 percent less than that of plasma PCs. Platelet quality was maintained if pooled Seto sol PCs were filtered on Day 1 and stored for over 4 days. Filtration did not alter platelet function in 1-day-old or 5-day-old Seto sol PCs.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Programmable pH buffers

    DOEpatents

    Gough, Dara Van; Huber, Dale L.; Bunker, Bruce C.; Roberts, Mark E.

    2017-01-24

    A programmable pH buffer comprises a copolymer that changes pK.sub.a at a lower critical solution temperature (LCST) in water. The copolymer comprises a thermally programmable polymer that undergoes a hydrophobic-to-hydrophilic phase change at the LCST and an electrolytic polymer that exhibits acid-base properties that are responsive to the phase change. The programmable pH buffer can be used to sequester CO.sub.2 into water.

  18. A continuous acetic acid system for polyacrylamide gel electrophoresis of gliadins and other prolamines.

    PubMed

    Clements, R L

    1988-02-01

    A polyacrylamide gel electrophoresis system buffered by acetic acid alone was developed for electrophoresis of prolamines. When applied to gliadin electrophoresis, the acetic acid system produces more bands than does a conventional aluminum lactate-lactic acid system (using 12% acrylamide gels). The acetic acid system is relatively simple, requiring a single buffer component that is universally available in high purity.

  19. The greater negative charge density of DNA in tris-borate buffers does not enhance DNA condensation by multivalent cations.

    PubMed

    Schwinefus, J J; Bloomfield, V A

    2000-12-01

    As indicated by recent measurements of the electrophoretic free solution mobility, DNA appears to have a greater helical charge density in Tris-borate-EDTA (TBE) buffers than in Tris-acetate-EDTA (TAE) buffers. Since electrostatic forces play a major role in DNA packaging processes, we have investigated the condensation of closed circular plasmid DNA using total intensity and dynamic light scattering in Tris-borate, Tris-acetate, and Tris-cacodylate buffers with cobaltic hexa-amine (III) [Co(NH(3))(3+)(6)]. We find that neither the critical concentration of Co(NH(3))(3+)(6) nor the hydrodynamic radii of the resulting condensates vary significantly in the buffer systems studied here despite the prediction that DNA condensation should occur at significantly lower Co(NH(3))(3+)(6) concentrations in Tris-borate buffers. Assuming a persistence length behavior similar to B-DNA in the presence of multivalent cations, a decrease in the attractive counterion correlation pressure decay length in Tris-borate buffers does not account for our observations. It is possible that the binding of multivalent cations to DNA may hinder borate association with the DNA double helix.

  20. [The coagulation characteristics of human oxyhemoglobin in the presence of a mercury (II) ion in a neutral phosphate buffer].

    PubMed

    Bogdanova, L D; Myshkin, A E

    1990-01-01

    The kinetics of human oxyhemoglobin coagulation in neutral phosphate buffer in the presence of mercury acetate at 20 degrees has been studied using turbidimetric methods. The addition of small amounts of concentrated Hg2+ solution leads to rapid local protein coagulation with subsequent dissolution of the formed coagulate. Coagulation can be inhibited by addition of Tris that binds to mercury ions. The pattern of oxyhemoglobin coagulation is determined by molar Hg2+/protein ration rather than by total Hg2+ concentration.

  1. Prophylactic Effects of Garlic Oil and Onion Oil Fractions as Compared to Vitamin E on Rats Orally Fed with Lead Acetate Solution.

    PubMed

    Sajitha, G R; Augusti, K T; Jose, Regi

    2016-07-01

    Heavy metal pollution is a global public health challenge due to its stable and persistent environmental contamination. Of these lead is considered to be one of the most common ubiquitous and industrial pollutants and at low concentration it exerts extensive damages to the tissues. Daily feeding of lead acetate solution (Dose: 10 mg/kg/day) to normal rats for a month adversely altered the parameters of blood, serum and tissues, viz; RBC, WBC, Hb, ɗ- ALAD (Delta amino levulinic acid dehydratase), Pb content, lipids, oxidized lipids (TBARS), vitamins C and E and GSH levels and activities of AST, ALT and antioxidant enzymes viz; catalase, GR, Gpx and SOD. In order to study whether antioxidants have any effect to counteract the toxicity of lead we have selected comparatively better active allium fractions for the study viz: polar fraction of garlic (PFG) and polar fraction of onion (PFO). On feeding of these active fractions of garlic and onion oils i.e. their polar fractions and vitamin E (Dose 100 mg/kg/day) separately for a month along with or without lead acetate to rats each nutraceutical and vitamin E counteracted the adverse effects of Pb significantly (p ≤ 0.05). Their effects are in the order of PFG > PFO > Vitamin E. All these results point out that garlic and onion oils contain natural disulfoxide compounds which act as antioxidant and anti toxic to lead compounds. Their comparative differences in action may be due to the presence and position of double bonds and disulfide oxide bonds in their molecules. i.e., in PFG the allyl disulfide oxide group is present and in PFO saturated methyl and propyl groups and unsaturated propenyl group are present in place of allyl groups. The former group confers a better antioxidant activity on PFG, while the latter groups confer a lesser activity on PFO.

  2. Thallium acetate

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 30 , 2009 , the assessment summary for Thallium acetate is included in t

  3. Phenylmercuric acetate

    Integrated Risk Information System (IRIS)

    Phenylmercuric acetate ; CASRN 62 - 38 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  4. Ethyl acetate

    Integrated Risk Information System (IRIS)

    Ethyl acetate ; CASRN 141 - 78 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  5. Ammonium acetate

    Integrated Risk Information System (IRIS)

    Ammonium acetate ; CASRN 631 - 61 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  6. Vinyl acetate

    Integrated Risk Information System (IRIS)

    Vinyl acetate ; CASRN 108 - 05 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  7. An all chemical solution deposition approach for the growth of highly textured CeO2 cap layers on La2Zr2O7-buffered long lengths of biaxially textured Ni W substrates for YBCO-coated conductors

    NASA Astrophysics Data System (ADS)

    Engel, S.; Knoth, K.; Hühne, R.; Schultz, L.; Holzapfel, B.

    2005-10-01

    A reel-to-reel, dip coating process has been developed to continuously deposit epitaxial La2Zr2O7 (LZO) and CeO2 on 5 m long cube-textured {100} (001)Ni tapes. Recent results for La2Zr2O7 and CeO2 buffer layers deposited on long lengths of Ni substrate for the realization of YBa2Cu3O7-x (YBCO)-coated conductors are presented. The major achievement is the development of a new all chemical solution deposition (CSD) process leading to the formation of highly textured buffer layers at moderate annealing temperatures. Reproducible highly textured, dense and crack-free LZO buffer layers and CeO2 cap layers were obtained for annealing temperatures as low as 900 °C in a reducing atmosphere (Ar-5 at.%-H2). The thickness of the LZO buffer layers was determined to be (200 ± 10) nm per single coating; prepared cerium oxide layers showed a thickness of 60 nm ± 10 nm. Pulsed laser deposition (PLD) was used to grow YBCO films on these substrates. A Tc 0 of T = 90.5 K and ΔTc = 1.4 K was obtained on PLD-YBCO/CSD-CeO2 /CSD-LZO/Ni-5 at.% W, which shows the outstanding features of this new buffer layer architecture processed by CSD. The large layer thickness combined with low annealing temperatures is the main advantage of this new process for low-cost buffer layer deposition on Ni-RABiTS (rolling-assisted biaxially textured substrates).

  8. Assessment of Chemical Solution Synthesis and Properties of Gd2Zr2O7 Thin Films as Buffer Layers for Second-Generation High-Temperature Superconductor Wires (Postprint)

    DTIC Science & Technology

    2012-02-01

    due to differing chemical envi- ronment through the GZO layer, specifically caused by the variable carbon distribution. The performance of the MOD...deposition of lanthanum zirconate barrier layers applied to low-cost coated-conductor fabrication. J. Mater. Res. 19, 2117 (2004). 11. T. Aytug, M...cal solution deposition of lanthanum zirconate buffer layers on biaxially textured Ni–1.7% Fe–3% W alloy substrates for coated- conductor

  9. Adaptively biased sequential importance sampling for rare events in reaction networks with comparison to exact solutions from finite buffer dCME method.

    PubMed

    Cao, Youfang; Liang, Jie

    2013-07-14

    Critical events that occur rarely in biological processes are of great importance, but are challenging to study using Monte Carlo simulation. By introducing biases to reaction selection and reaction rates, weighted stochastic simulation algorithms based on importance sampling allow rare events to be sampled more effectively. However, existing methods do not address the important issue of barrier crossing, which often arises from multistable networks and systems with complex probability landscape. In addition, the proliferation of parameters and the associated computing cost pose significant problems. Here we introduce a general theoretical framework for obtaining optimized biases in sampling individual reactions for estimating probabilities of rare events. We further describe a practical algorithm called adaptively biased sequential importance sampling (ABSIS) method for efficient probability estimation. By adopting a look-ahead strategy and by enumerating short paths from the current state, we estimate the reaction-specific and state-specific forward and backward moving probabilities of the system, which are then used to bias reaction selections. The ABSIS algorithm can automatically detect barrier-crossing regions, and can adjust bias adaptively at different steps of the sampling process, with bias determined by the outcome of exhaustively generated short paths. In addition, there are only two bias parameters to be determined, regardless of the number of the reactions and the complexity of the network. We have applied the ABSIS method to four biochemical networks: the birth-death process, the reversible isomerization, the bistable Schlögl model, and the enzymatic futile cycle model. For comparison, we have also applied the finite buffer discrete chemical master equation (dCME) method recently developed to obtain exact numerical solutions of the underlying discrete chemical master equations of these problems. This allows us to assess sampling results objectively

  10. Adaptively biased sequential importance sampling for rare events in reaction networks with comparison to exact solutions from finite buffer dCME method

    NASA Astrophysics Data System (ADS)

    Cao, Youfang; Liang, Jie

    2013-07-01

    Critical events that occur rarely in biological processes are of great importance, but are challenging to study using Monte Carlo simulation. By introducing biases to reaction selection and reaction rates, weighted stochastic simulation algorithms based on importance sampling allow rare events to be sampled more effectively. However, existing methods do not address the important issue of barrier crossing, which often arises from multistable networks and systems with complex probability landscape. In addition, the proliferation of parameters and the associated computing cost pose significant problems. Here we introduce a general theoretical framework for obtaining optimized biases in sampling individual reactions for estimating probabilities of rare events. We further describe a practical algorithm called adaptively biased sequential importance sampling (ABSIS) method for efficient probability estimation. By adopting a look-ahead strategy and by enumerating short paths from the current state, we estimate the reaction-specific and state-specific forward and backward moving probabilities of the system, which are then used to bias reaction selections. The ABSIS algorithm can automatically detect barrier-crossing regions, and can adjust bias adaptively at different steps of the sampling process, with bias determined by the outcome of exhaustively generated short paths. In addition, there are only two bias parameters to be determined, regardless of the number of the reactions and the complexity of the network. We have applied the ABSIS method to four biochemical networks: the birth-death process, the reversible isomerization, the bistable Schlögl model, and the enzymatic futile cycle model. For comparison, we have also applied the finite buffer discrete chemical master equation (dCME) method recently developed to obtain exact numerical solutions of the underlying discrete chemical master equations of these problems. This allows us to assess sampling results objectively

  11. An improvement to the ligand optimisation method (LOM) for measuring the apparent dissociation constant and ligand purity in Ca2+ and Mg2+ buffer solutions.

    PubMed

    McGuigan, John A S; Kay, James W; Elder, Hugh Y

    2014-01-01

    In Ca(2+)/Mg(2+) buffers the calculated ionised concentrations ([X(2+)]) can vary by up to a factor of seven. Since there are no defined standards it is impossible to check calculated [X(2+)], making measurement essential. The ligand optimisation method (LOM) is an accurate method to measure [X(2+)] in Ca(2+)/Mg(2+) buffers; independent estimation of ligand purity extends the method to pK(/) < 4. To simplify calculation, Excel programs ALE and AEC were compiled for LOM and its extension. This paper demonstrates that the slope of the electrode in the pX range 2.000-3.301 deviates from Nernstian behaviour as it depends on the value of the lumped interference, Σ. ALE was modified to include this effect; this modified program SALE, and the programs ALE and AEC were used on simulated data for Ca(2+)-EGTA and Mg(2+)-ATP buffers, to calculate electrode and buffer characteristics as a function of Σ. Ca(2+)-electrodes have a Σ < 10(-6) mol/l and there was no difference amongst the three methods. The Σ for Mg(2+)-electrodes lies between 10(-5) and 1.5 (∗) 10(-5) mol/l and calculated [Mg(2+)] with ALE were around 3% less than the true value. SALE and AEC correctly predicted [Mg(2+)]. SALE was used to recalculate K(/) and pK(/) on measured data for Ca(2+)-EGTA and Mg(2+)-EDTA buffers. These results demonstrated that it is pK(/) that is normally distributed. Until defined standards are available, [X(2+)] in Ca(2+)/Mg(2+) buffers have to be measured. The most appropriate method is to use Ca(2+)/Mg(2) electrodes combined with the Excel programs SALE or AEC.

  12. Pyrroloquinoline quinone (PQQ) is reduced to pyrroloquinoline quinol (PQQH2) by vitamin C, and PQQH2 produced is recycled to PQQ by air oxidation in buffer solution at pH 7.4.

    PubMed

    Mukai, Kazuo; Ouchi, Aya; Nagaoka, Shin-ichi; Nakano, Masahiko; Ikemoto, Kazuto

    2015-01-01

    Measurements of the reaction of sodium salt of pyrroloquinoline quinone (PQQNa2) with vitamin C (Vit C) were performed in phosphate-buffered solution (pH 7.4) at 25 °C under nitrogen atmosphere, using UV-vis spectrophotometry. The absorption spectrum of PQQNa2 decreased in intensity due to the reaction with Vit C and was changed to that of pyrroloquinoline quinol (PQQH2, a reduced form of PQQ). One molecule of PQQ was reduced by two molecules of Vit C producing a molecule of PQQH2 in the buffer solution. PQQH2, thus produced, was recycled to PQQ due to air oxidation. PQQ and Vit C coexist in many biological systems, such as vegetables, fruits, as well as in human tissues. The results obtained suggest that PQQ is reduced by Vit C and functions as an antioxidant in biological systems, because it has been reported that PQQH2 shows very high free-radical scavenging and singlet-oxygen quenching activities in buffer solutions.

  13. Studies on electrochemical characterization and performance prediction of cellulose acetate and Zeocarb-225 composite membranes in aqueous NaCl solutions.

    PubMed

    Tiwari, A K; Ahmad, Suhail

    2006-06-01

    We have mixed cellulose acetate and Zeocarb-225 in different ratios, leading to the preparations of Membrane-1 and Membrane-2. Membrane potential, water content, and conductance measurements have been carried out to estimate and analyze the data in terms of equilibria and important electrochemical parameters. The Donnan equilibrium has been incorporated to estimate the activity coefficient of counterions, y(p)M, and solute, y(+/-)M in the membrane phase along with the parameter, so called varphi expressing non-ideality. Dependence of the extent of hydrophilicity of both membranes on mean electrolyte concentrations has been examined. Selectivity in membranes is discussed in terms of dissociation equilibria, K(d)s and K(d)f. It has been found that membrane surface charge density sigma(s) increases with increasing of external NaCl concentration. Dependence of water transport number and cationic transport number on electrolyte concentration shows a similar trend of variation. At higher mean concentration of electrolyte, water transport number in Membrane-2 has a negative value. Membrane-2 has a higher value of water transport number than Membrane-1. The entropy production due to solute and water transport has been quantified for both the membranes in the light of nonequilibrium thermodynamics. The various type of interactions such as solute-membrane, solute-water, and water-membrane are analyzed in terms of friction coefficients (f(ij)) of Spiegler's frictional pore model. In our case, an f(wm) < f(sm) < f(sw)-like trend is observed in both membranes. These frictional coefficients show close dependence on external electrolyte concentrations. Pore potential values of Membrane-1 and Membrane-2 have been worked out using the Poisson-Boltzmann equation. In both systems pore potential values increase with increasing mean electrolyte concentrations. The transport through Membrane-1 and Membrane-2 tends to follow diffusion-control criteria, i.e., (D(+/-) . C. d/D(+/-)M C

  14. Electromigration of a heteroconjugated imidazole-acetate complex in ACN.

    PubMed

    Porras, Simo P; Jussila, Matti

    2007-10-01

    ACN is an extremely poor hydrogen bond donor and therefore the anions dissolved in it are solvated mainly by other hydrogen bond donors (e.g. uncharged acids) possibly present in the solution. Under properly selected experimental conditions stabilization via hydrogen bonding can be used for separation in CE as has been demonstrated for uncharged acids by several authors. Electromigration based on heteroconjugation can be of importance, e.g. when aqueous separation medium cannot be used due to stability reasons. It also allows CE to be used as a tool for solution chemistry measurements, if the required physicochemical properties of the studied system are known or they can be predicted with sufficient accuracy by existing theories. In the present work we showed that also an uncharged base can stabilize an anion via hydrogen bonding in ACN. In the setup imidazole was chosen as a model base and acetate ion as complexing anion in equimolar acetic acid-acetate buffer. The resulted hydrogen-bonded imidazole-acetate complex (i.e. heteroconjugate) possesses a charge and can thus migrate in CE. It was shown that the studied complexation in ACN is sensitive to competition by other hydrogen bond donors such as water and methanol. On the other hand, acetone, which is a poor hydrogen bond donor, did not have much effect on the complexation. To take the effect of ionic strength on mobility into account, mobilities of the imidazole-acetate complex measured at various ionic strengths were corrected to zero ionic strength by the aid of conductivity equation. A fit of the 1:1 binding isotherm to the ionic strength corrected mobility versus acetate concentration data led to rather good correlation. However, x-reciprocal linear transformation of the binding isotherm showed nonlinearity, which could be partly explained by homoconjugation of acetic acid and acetate ion. Since the homoconjugation constant for acetic acid under present experimental conditions was not available, theoretical

  15. Dissolution reaction and surface iron speciation of UICC crocidolite in buffered solution at pH 7.4: A combined ICP-OES, XPS and TEM investigation

    NASA Astrophysics Data System (ADS)

    Pacella, Alessandro; Fantauzzi, Marzia; Turci, Francesco; Cremisini, Carlo; Montereali, Maria Rita; Nardi, Elisa; Atzei, Davide; Rossi, Antonella; Andreozzi, Giovanni B.

    2014-02-01

    The dissolution reaction and the surface modifications of crocidolite asbestos fibres incubated for 0.5, 1, 24, 48, 168 and 1440 h in a phosphate buffered solution at pH 7.4 with and without hydrogen peroxide were investigated. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used to monitor the ion release into solution, X-ray Photoelectron Spectroscopy (XPS) was performed to unveil the chemistry of the leached surface, and High Resolution Transmission Electron Microscopy (HR-TEM) was carried out to monitor the structural modifications of the fibres. No significant differences were observed between dissolution experiments carried out with and without H2O2 with the exception of results after the first hour, from which it may be inferred that the dissolution proceeds faster in the presence of H2O2 but only in its very early steps. Congruent mobilization of Si and Mg from crocidolite was observed, increasing with time especially in the range between 1 and 48 h, while Ca decreased after 48 h and Fe was not detected at any incubation time. In the undersaturated conditions (0-48 h), dissolution rate of UICC crocidolite fibres has been estimated to be d(Si)/dt = 0.079 μmol h-1. The fibre surface modification is continuous with time: XPS results showed a regular depletion of Si and Mg and enrichment of Fe along dissolution. The Fe2p3/2 signal on the surface was fitted with four components at 709.0, 710.5, 711.6 and 712.8 eV binding energy values corresponding to: (i) Fe(II)-O and (ii) Fe(III)-O surrounded by oxygen atoms in the silicate structure, (iii) Fe(III)-OOH as a product of the dissolution process, and (iv) Fe in a phosphate precipitate (Fe-P), respectively. The evolution of Fe speciation on the crocidolite surface was followed by integrating the four photoemission peaks, and results showed that the oxidative environment promotes the formation of Fe(III)-O (up to 37% Fetot) and of Fe-P species (up to 16% Fetot), which are found on the fibre

  16. The Effective Diffusion Coefficient of Dissolved Oxygen and Oxidation Rate of Pyrite by Dissolved Oxygen in Compacted Purified and Crude Sodium Bentonites in Carbonate Buffered Solution

    SciTech Connect

    Manaka, Mitsuo

    2003-09-15

    Immediately after the geological disposal of high-level radioactive waste, the oxygen initially existing in the repository is expected to strongly affect the redox condition of the near field. The oxygen dissolves in the groundwater, is transported by diffusion through it, and is consumed by the oxidation of pyrite as an impurity in bentonite. To assess the influence of the oxygen, this study was conducted to estimate the diffusion of dissolved oxygen (DO) and the rate of pyrite oxidation by DO in compacted purified and crude sodium bentonites (SBs) in more detail than the Manaka et al. study. The effective diffusion coefficient (De) of DO in the compacted purified SB was measured in low ionic strength solution (carbonate buffered solution with pH {approx} 9) using the electrochemical method. The empirical equation between De value of DO and dry density (0.5 x 10{sup 3}-1.8 x 10{sup 3} kg m{sup -3}) of purified SB was obtained as follows:De{sub DO}{sup Kunipia-F} = 8.2 {+-} 1.5 x 10{sup -10}x exp(-2.6 {+-} 0.2 x10{sup -3}{rho},where De{sub DO}{sup Kunipia-F} is the De of DO in compacted purified SB (Kunipia F) (m{sup 2} s{sup -1}) and {rho} is the dry density of the SB (kg m{sup -3}).On the other hand, the De value of DO in the compacted crude SB was estimated using the relationship between De values of tritiated water in compacted purified and crude SBs. The empirical equation between the De value of DO and dry density (0.5 x 10{sup 3}-1.8 x 10{sup 3} kg m{sup -3}) of crude SB was derived as follows:De{sub DO}{sup Kunigel-V1} = 2.04 x 10{sup -9} exp(-2.6 x 10{sup -3}{rho}),where De{sub DO}{sup Kunigel-V1} is the De of DO in compacted crude SB (Kunigel V1) (m{sup 2} s{sup -1}) and {rho} is the dry density of the SB (kg m{sup -3}).The rates of pyrite oxidation by DO were estimated from the experimental data in pyrite-purified SB systems using the obtained De values of DO. The relation between rate constant (k') of pyrite oxidation by DO and dry density ({rho}) of

  17. CdS/CdSe-sensitized solar cell based on Al-doped ZnO nanoparticles prepared by the decomposition of zinc acetate solid solution

    NASA Astrophysics Data System (ADS)

    Deng, Jianping; Wang, Minqiang; Ye, Wei; Fang, Junfei; Zhang, Pengchao; Yang, Yongping; Yang, Zhi

    2017-01-01

    In the study, Al-doped ZnO nanoparticles (Al-ZnO NPs) were prepared by the decomposition of zinc acetate solid solution. The X-ray diffraction results showed that Al3+ was successfully doped without the formation of Al and Al2O3 impurity phases. The less Al-doping did not change the hexagonal wurtzite crystal structure of ZnO. The ratio of Al to Al + Zn (9.05%) measured by the energy dispersive X-ray also confirmed the formation of Al-ZnO. The Al-ZnO NPs were used as the photoanode material to prepare CdS/CdSe-sensitized solar cell. Compared with the cell based on commercial ZnO NPs (C-ZnO), the short-circuit current density and the fill factor of the cell were increased from 5.8 mA/cm2 and 34.1% (C-ZnO) to 7.78 mA/cm2 and 48.7% (Al-ZnO), respectively. The cell efficiency was increased from 1.01% (C-ZnO) to (1.9%) (Al-ZnO) and the increase percentage reached 88.1%. The results of electrochemical impedance spectroscopy and open-circuit voltage-decay suggested the lower carrier transport resistance and the longer electron lifetime of Al-ZnO-based cell.

  18. 1-Naphthyl Acetate-Dependent Medium Acidification by Zea mays L. Coleoptile Segments 1

    PubMed Central

    Salguero, Julio; Calatayud, Angeles; Gonzalez-Daros, Francisco; del Valle-Tascon, Secundino

    1991-01-01

    Zea mays L. cv INRA 5a coleoptile segments ecidify the incubation medium on the addition of 1-naphthyl acetate (1-NA). The buffering capacity of the bathing solution increases during 1-NA stimulated medium acidification. The solution bathing the 1-NA treated coleoptile segment was analyzed by high performance liquid chromatography. A considerable amount of acetic acid was detected in the bathing solution used to measure 1-NA-dependent medium acidification. For the first time, the data demonstrate directly the release of acetic acid from 1-NA. The extent of medium acidification was proportional to 1-NA concentration. Simultaneous measurement of medium acidification and acetate content upon addition of 1-NA showed that both processes were temporally correlated. The stoichiometry of proton equivalents to acetate ion was 0.966. Addition of 50 micromolar N,N′-dicyclohexylcarbodiimide had little effect on 1-NA-dependent medium acidification. The results indicate that 1-NA is hydrolyzed in the extracellular space of coleoptile cells. PMID:16668108

  19. Properties of Pb(0.92)La(0.08)Zr(0.52)Ti(0.48)O(3) thin films grown on SrRuO(3) buffered nickel and silicon substrates by chemical solution deposition

    SciTech Connect

    Narayanan, M.; Ma, B.; Tong, S.; Koritala, R.; Balachandran, U.

    2012-01-01

    Ferroelectric film-on-foil capacitors are suitable to replace discrete passive components in the quest to develop electronic devices that show superior performance and are smaller in size. The film-on-foil approach is the most practical method to fabricate such components. Films of Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} (PLZT) were deposited on SrRuO{sub 3} (SRO) buffer films over nickel and silicon substrates. High-quality polycrystalline SRO thin-film electrodes were first deposited by chemical solution deposition. A phase pure, dense, uniform microstructure with grain size <100 nm was obtained in films crystallized at 700 C. The room-temperature resistivity of the SRO films crystallized at 700 C was {approx}800-900 {mu}{Omega}-cm. The dielectric properties of sol-gel derived PLZT capacitors on SRO-buffered nickel were evaluated as a function of temperature, bias field, and frequency, and the results were compared to those of the same films on silicon substrates. The comparison demonstrated the integrity of the buffer layer and its compatibility with nickel substrates. Device-quality dielectric properties were measured on PLZT films deposited on SRO-buffered nickel foils and found to be superior to those for PLZT on SRO-buffered silicon and expensive platinized silicon. These results suggest that SRO films can act as an effective barrier layer on nickel substrates suitable for embedded capacitor applications.

  20. Dependence of Device Characteristics of Bulk-Heterojunction Organic Thin-Film Solar Cells on Concentration of Glycerol and Sorbitol Addition in Pedot:. PSS Solutions for Fabricating Buffer Layers

    NASA Astrophysics Data System (ADS)

    Yamaki, Yusuke; Marumoto, Kazuhiro; Fujimori, Takuya; Mori, Tatsuo

    We have investigated the dependence of device characteristics of bulk-heterojunction organic thin-film solar cells on the concentration of glycerol and sorbitol addition in poly(3,4-ethylenedioxy thiophene):poly(4-styrene sulfonate) (PEDOT:PSS) solutions for fabricating buffer layers. The device structure is ITO/buffer/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM)/Al. Glycerol addition is effective for increasing power conversion efficiency (PCE) from 1.25 to 1.41% because of the increase in short-circuit current density (Jsc) without decreasing open-circuit voltage (Voc). On the other hand, sorbitol addition decreases PCE from 1.25 to 1.04%, owing to the decrease in Voc. This difference in Voc behavior is ascribed to different work function of PEDOT:PSS with glycerol and sorbitol treatment.

  1. Are buffers boring? Uniqueness and asymptotical stability of traveling wave fronts in the buffered bistable system.

    PubMed

    Tsai, Je-Chiang; Sneyd, James

    2007-04-01

    Traveling waves of calcium are widely observed under the condition that the free cytosolic calcium is buffered. Thus it is of physiological interest to determine how buffers affect the properties of calcium waves. Here we summarise and extend previous results on the existence, uniqueness and stability of traveling wave solutions of the buffered bistable equation, which is the simplest possible model of the upstroke of a calcium wave. Taken together, the results show that immobile buffers do not change the existence, uniqueness or stability of the traveling wave, while mobile buffers can eliminate a traveling wave. However, if a wave exists in the latter case, it remains unique and stable.

  2. Solubility of acetic acid and trifluoroacetic acid in low-temperature (207-245 k) sulfuric acid solutions: implications for the upper troposphere and lower stratosphere.

    PubMed

    Andersen, Mads P Sulbaek; Axson, Jessica L; Michelsen, Rebecca R H; Nielsen, Ole John; Iraci, Laura T

    2011-05-05

    The solubility of gas-phase acetic acid (CH(3)COOH, HAc) and trifluoroacetic acid (CF(3)COOH, TFA) in aqueous sulfuric acid solutions was measured in a Knudsen cell reactor over ranges of temperature (207-245 K) and acid composition (40-75 wt %, H(2)SO(4)). For both HAc and TFA, the effective Henry's law coefficient, H*, is inversely dependent on temperature. Measured values of H* for TFA range from 1.7 × 10(3) M atm(-1) in 75.0 wt % H(2)SO(4) at 242.5 K to 3.6 × 10(8) M atm(-1) in 40.7 wt % H(2)SO(4) at 207.8 K. Measured values of H* for HAc range from 2.2 × 10(5) M atm(-1) in 57.8 wt % H(2)SO(4) at 245.0 K to 3.8 × 10(8) M atm(-1) in 74.4 wt % H(2)SO(4) at 219.6 K. The solubility of HAc increases with increasing H(2)SO(4) concentration and is higher in strong sulfuric acid than in water. In contrast, the solubility of TFA decreases with increasing sulfuric acid concentration. The equilibrium concentration of HAc in UT/LS aerosol particles is estimated from our measurements and is found to be up to several orders of magnitude higher than those determined for common alcohols and small carbonyl compounds. On the basis of our measured solubility, we determine that HAc in the upper troposphere undergoes aerosol partitioning, though the role of H(2)SO(4) aerosol particles as a sink for HAc in the upper troposphere and lower stratosphere will only be discernible under high atmospheric sulfate perturbations.

  3. Buffer Zone Fact Sheets

    EPA Pesticide Factsheets

    New requirements for buffer zones and sign posting contribute to soil fumigant mitigation and protection for workers and bystanders. The buffer provides distance between the pesticide application site and bystanders, reducing exposure risk.

  4. Comparison of phosphorus forms in three extracts of dairy feces by solution 31P NMR analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using solution 31P NMR spectroscopy, we compared three extractants, deionized water, sodium acetate buffer (pH 5.0) with fresh sodium dithionite (NaAc-SD), and 0.25 M NaOH-0.05 M EDTA (NaOH-EDTA), for the profile of P compounds in two dairy fecal samples. Phosphorus extracted was 35% for water, and...

  5. Solute-solvent interactions in micellar electrokinetic chromatography. 6. Optimization of the selectivity of lithium dodecyl sulfate-lithium perfluorooctanesulfonate mixed micellar buffers.

    PubMed

    Fuguet, Elisabet; Ràfols, Clara; Torres-Lapasió, José Ramón; García-Alvarez-Coque, María Celia; Bosch, Elisabeth; Rosés, Martí

    2002-09-01

    The optimization of the composition of mixed surfactants used as micellar electrokinetic chromatography (MEKC) pseudostationary phases is proposed as an effective method for the separation of complex mixtures of analytes. The solvation parameter model is used to select two surfactants (lithium dodecyl sulfate, LDS, and lithium perfluorooctanesulfonate, LPFOS) with contrasting solvation properties. Combination of these two surfactants allows variations of the solvation properties of MEKC pseudostationary phase along a wide range. Thus, the convenient variation of the proportion of both surfactants allows an effective control of the selectivity in such systems. An algorithm that predicts the overall resolution of a given mixture of compounds is described and applied to optimize the composition of the mixed surfactant for the separation of the mixture. The algorithm is based on the calculation of peak purities on simulated chromatograms as a function of the composition of the mixed LDS/LPFOS micellar buffer from data at several micellar buffer compositions. Successful separations were achieved for mixtures containing up to 20 compounds, in less than 12 min.

  6. 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.

  7. Acetate induced enhancement of photocatalytic hydrogen peroxide production from oxalic acid and dioxygen.

    PubMed

    Yamada, Yusuke; Nomura, Akifumi; Miyahigashi, Takamitsu; Ohkubo, Kei; Fukuzumi, Shunichi

    2013-05-09

    The addition of acetate ion to an O2-saturated mixed solution of acetonitrile and water containing oxalic acid as a reductant and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh(+)-NA) as a photocatalyst dramatically enhanced the turnover number of hydrogen peroxide (H2O2) production. In this photocatalytic H2O2 production, a base is required to facilitate deprotonation of oxalic acid forming oxalate dianion, which acts as an actual electron donor, whereas a Brønsted acid is also necessary to protonate O2(•-) for production of H2O2 by disproportionation. The addition of acetate ion to a reaction solution facilitates both the deprotonation of oxalic acid and the protonation of O2(•-) owing to a pH buffer effect. The quantum yield of the photocatalytic H2O2 production under photoirradiation (λ = 334 nm) of an O2-saturated acetonitrile-water mixed solution containing acetate ion, oxalic acid and QuPh(+)-NA was determined to be as high as 0.34, which is more than double the quantum yield obtained by using oxalate salt as an electron donor without acetate ion (0.14). In addition, the turnover number of QuPh(+)-NA reached more than 340. The reaction mechanism and the effect of solvent composition on the photocatalytic H2O2 production were scrutinized by using nanosecond laser flash photolysis.

  8. Method for regeneration of electroless nickel plating solution

    DOEpatents

    Eisenmann, Erhard T.

    1997-01-01

    An electroless nickel(EN)/hypophosphite plating bath is provided employing acetic acid/acetate as a buffer and which is, as a result, capable of perpetual regeneration while avoiding the production of hazardous waste. A regeneration process is provided to process the spent EN plating bath solution. A concentrated starter and replenishment solution is provided for ease of operation of the plating bath. The regeneration process employs a chelating ion exchange system to remove nickel cations from spent EN plating solution. Phosphites are then removed from the solution by precipitation. The nickel cations are removed from the ion exchange system by elution with hypophosphorous acid and the nickel concentration of the eluate adjusted by addition of nickel salt. The treated solution and adjusted eluate are combined, stabilizer added, and the volume of resulting solution reduced by evaporation to form the bath starter and replenishing solution.

  9. Method for regeneration of electroless nickel plating solution

    DOEpatents

    Eisenmann, E.T.

    1997-03-11

    An electroless nickel(EN)/hypophosphite plating bath is provided employing acetic acid/acetate as a buffer and which is, as a result, capable of perpetual regeneration while avoiding the production of hazardous waste. A regeneration process is provided to process the spent EN plating bath solution. A concentrated starter and replenishment solution is provided for ease of operation of the plating bath. The regeneration process employs a chelating ion exchange system to remove nickel cations from spent EN plating solution. Phosphites are then removed from the solution by precipitation. The nickel cations are removed from the ion exchange system by elution with hypophosphorus acid and the nickel concentration of the eluate adjusted by addition of nickel salt. The treated solution and adjusted eluate are combined, stabilizer added, and the volume of resulting solution reduced by evaporation to form the bath starter and replenishing solution. 1 fig.

  10. Thermophysical properties of lysozyme (protein) solutions

    NASA Technical Reports Server (NTRS)

    Liu, Jiaching; Yang, Wen-Jei

    1992-01-01

    Thermophysical properties of protein solutions composed of the lysozyme crystals with a 0.1 M sodium acetate and 5 percent NaCl solution as the buffer (pH = 4.0) are determined. The properties being measured include specific heat, thermal conductivity, dynamic viscosity, and surface tension. The protein concentrations are varied. Thermal diffusivity is calculated using the measured results. The purpose of the research is to measure thermophysical properties of lysozyme solutions which would serve as the data bank for controlling and modeling the crystal growth process on earth as well as in space.

  11. Organellar calcium buffers.

    PubMed

    Prins, Daniel; Michalak, Marek

    2011-03-01

    Ca(2+) is an important intracellular messenger affecting many diverse processes. In eukaryotic cells, Ca(2+) storage is achieved within specific intracellular organelles, especially the endoplasmic/sarcoplasmic reticulum, in which Ca(2+) is buffered by specific proteins known as Ca(2+) buffers. Ca(2+) buffers are a diverse group of proteins, varying in their affinities and capacities for Ca(2+), but they typically also carry out other functions within the cell. The wide range of organelles containing Ca(2+) and the evidence supporting cross-talk between these organelles suggest the existence of a dynamic network of organellar Ca(2+) signaling, mediated by a variety of organellar Ca(2+) buffers.

  12. Comparison of kinetic models to describe high pressure and gamma irradiation used to inactivate Vibrio vulnificus and Vibrio parahaemolyticus prepared in buffer solution and in whole oysters.

    PubMed

    Hu, Xiaopei; Mallikarjunan, Parameswarakumar; Koo, Jaheon; Andrews, Linda S; Jahncke, Michael L

    2005-02-01

    Comparisons of different models in inactivation kinetics were conducted on data obtained from high-pressure and gamma-irradiation processing. Vibrio vulnificus (MO-624) and Vibrio parahaemolyticus (O3:K6 TX-2103) suspended in phosphate-buffered saline (pH 7.4, 10(7) CFU/ml) were exposed to pressures from 207 to 379 MPa for 1 to 20 min. Inoculated whole oysters (106 CFU/g) were exposed to pressure from 276 to 379 MPa for 1 to 15 min. Pure cultures and inoculated oysters (10(6) CFU/g) also were irradiated (gamma irradiation) at doses of less than 3 kGy. Four mathematical models, the Bigelow model, Arrhenius equation, Fermi equation, and Weibull frequency distributions, were applied to microbial survival data, and performances of the different kinetic models were compared. Weibull frequency distributions can predict the high-pressure inactivation of Vibrio spp. with more accuracy in both pure cultures and inoculated oyster samples. The Fermi model provided a better description of gamma-irradiation inactivation kinetics compared with the traditional Bigelow model.

  13. Immunolocalization of MAP-2 in routinely formalin-fixed, paraffin-embedded guinea pig brain sections using microwave irradiation: a comparison of different combinations of antibody clones and antigen retrieval buffer solutions.

    PubMed

    Kan, Robert K; Pleva, Christina M; Hamilton, Tracey A; Petrali, John P

    2005-04-01

    The present study was designed to evaluate the efficacy of different microwave pretreatment methods to retrieve microtubule-associated protein 2 (MAP-2) immunoreactivity in formalin-fixed, paraffin-embedded guinea pig brain sections. Brain sections, microwave pretreated in boiling sodium citrate, citric acid, Tris hydrochloride, and EDTA buffers of pH 4, 6, and 8, were labeled with four different clones of MAP-2 monoclonal antibodies. No MAP-2 immunoreactivity was observed in control sections processed without microwave pretreatment. Optimal MAP-2 immunoreactivity was observed only when MAP-2 antibody clone AP18 was used in conjunction with citric acid buffer of pH 6.0. Using this combination, brain sections from nerve agent soman-exposed guinea pigs were found to exhibit marked reduction in MAP-2 immunostaining in the hippocampus. These observations suggest that the clone of the antibody in addition to the type and pH of antigen retrieval (AR) solution are important variables to be considered for establishing an optimal AR technique. When studying counterpart antigens of species other than that to which the antibodies were originally raised, different antibody clones must be tested in combination with different microwave-assisted AR (MAR) methods. This MAR method makes it possible to conduct retrospective studies on archival guinea pig brain paraffin blocks to evaluate changes in neuronal MAP-2 expression as a consequence of chemical warfare nerve agent toxicity.

  14. 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.

  15. 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

  16. Automatic determination of ligand purity and apparent dissociation constant (K(app)) in Ca(2+)/Mg(2+) buffer solutions and the K(app) for Ca(2+)/Mg(2+) anion binding in physiological solutions from Ca(2+)/Mg(2+)-macroelectrode measurements.

    PubMed

    Kay, James W; Steven, Rachel J; McGuigan, John A S; Elder, Hugh Y

    2008-01-01

    Calibration of Ca(2+)/Mg(2+) macroelectrodes and flurochromes in the nmolar and mumolar range, respectively, require the use of buffer solutions. In these buffers the apparent dissociation constant (K(app)) has to be measured since calculation based on tabulated constants gives variable results. The ligand concentration [Ligand](T) has also to be estimated. The most accurate and general method for measuring both is the ligand optimisation method based on macroelectrode potential measurements, but this iterative method is time consuming, thus limiting its application. This paper describes an automatic program based on the method, which on entering the measured macroelectrode data calculates K(app), [Ligand](T) and the ionised concentration [X(2+)] within minutes. This optimisation method cannot be used at K(app) values greater than 0.1mM, but can be extended into this region if the anion concentration is known. The program has been modified to cover this eventuality. Ca(2+)/Mg(2+) macroelectrodes in conjunction with these programs offer an accurate, routine method for determining K(app) and [Ligand](T) in buffer solutions at the appropriate ionic strength, temperature and pH and the K(app) for divalent cations binding to physiological anions under experimental conditions.

  17. Separation of Cu2+, Cd2+ and Cr3+ in a Mixture Solution Using a Novel Carrier Poly(Methyl Thiazoleethyl Eugenoxy Acetate) with BLM (Bulk Liquid Membrane)

    NASA Astrophysics Data System (ADS)

    Djunaidi, M. C.; Khabibi; Ulumudin, I.

    2017-02-01

    The separation process using a novel carrier polyeugenol has active groups N and S has been done with the technique BLM. Polyeugenol has groups active N and S was synthesized from eugenol which is then polymerized into polyeugenol. This polymeric compounds was then acidified become acidic poly (eugenoksi acetate). After the acid formed, then the synthesis was continued by add 4-methyl-5-tiazoleetanol to form esters poly (methyl thiazole eugenoxy ethyl acetate) (PMTEEA). The result of the synthesis was analyzed by FTIR and 1H NMR. This polyester product synthesis was applied as a carrier for separating metal ions Cu2+, Cd2+ and Cr3+ with variations in feed phase pH = 5 and pH = 7 in the membrane of chloroform using techniques BLM. Receiving phase after 24 hours was analyzed by AAS. In variations of feed pH = 5 ions was obtained 66.21% Cd2+, 28.83% Cu2+ and 10.92% of Cr3+, at pH = 7 was obtained 70.77% Cd2+, 30.14% Cu2+, and 3.72% of Cr3+.

  18. Buffers more than buffering agent: introducing a new class of stabilizers for the protein BSA.

    PubMed

    Gupta, Bhupender S; Taha, Mohamed; Lee, Ming-Jer

    2015-01-14

    In this study, we have analyzed the influence of four biological buffers on the thermal stability of bovine serum albumin (BSA) using dynamic light scattering (DLS). The investigated buffers include 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), 4-(2-hydroxyethyl)-1-piperazine-propanesulfonic acid (EPPS), 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid sodium salt (HEPES-Na), and 4-morpholinepropanesulfonic acid sodium salt (MOPS-Na). These buffers behave as a potential stabilizer for the native structure of BSA against thermal denaturation. The stabilization tendency follows the order of MOPS-Na > HEPES-Na > HEPES ≫ EPPS. To obtain an insight into the role of hydration layers and peptide backbone in the stabilization of BSA by these buffers, we have also explored the phase transition of a thermoresponsive polymer, poly(N-isopropylacrylamide (PNIPAM)), a model compound for protein, in aqueous solutions of HEPES, EPPS, HEPES-Na, and MOPS-Na buffers at different concentrations. It was found that the lower critical solution temperatures (LCST) of PNIPAM in the aqueous buffer solutions substantially decrease with increase in buffer concentration. The mechanism of interactions between these buffers and protein BSA was probed by various techniques, including UV-visible, fluorescence, and FTIR. The results of this series of studies reveal that the interactions are mainly governed by the influence of the buffers on the hydration layers surrounding the protein. We have also explored the possible binding sites of BSA with these buffers using a molecular docking technique. Moreover, the activities of an industrially important enzyme α-chymotrypsin (α-CT) in 0.05 M, 0.5 M, and 1.0 M of HEPES, EPPS, HEPES-Na, and MOPS-Na buffer solutions were analyzed at pH = 8.0 and T = 25 °C. Interestingly, the activities of α-CT were found to be enhanced in the aqueous solutions of these investigated buffers. Based upon the Jones-Dole viscosity parameters, the

  19. Recovery of very dilute acetic acid using ion exchange

    SciTech Connect

    Cloete, F.L.D.; Marais, A.P.

    1995-07-01

    Acetic and related acids occur in many industrial wastewaters, often mixed with several other classes of organic compounds. Acetic acid can be recovered from 1% solutions using weakly basic ion exchange resins. The acid is adsorbed by the free-base form of the resin, which can then be eluted using a slurry of lime to give a solution of calcium acetate. This solution could either be evaporated to crystallize calcium acetate or reacted with sulfuric acid to form acetic acid and gypsum. Laboratory tests of the proposed process gave product solutions of 15--20% acetic acid using pure 1% acetic acid as feed. Some measurements using a typical industrial effluent gave similar recoveries and showed that there was no initial fouling of the resins.

  20. Basal buffer systems for a newly glycosylated recombinant human interferon-β with biophysical stability and DoE approaches.

    PubMed

    Kim, Nam Ah; Song, Kyoung; Lim, Dae Gon; Hada, Shavron; Shin, Young Kee; Shin, Sangmun; Jeong, Seong Hoon

    2015-10-12

    The purpose of this study was to develop a basal buffer system for a biobetter version of recombinant human interferon-β 1a (rhIFN-β 1a), termed R27T, to optimize its biophysical stability. The protein was pre-screened in solution as a function of pH (2-11) using differential scanning calorimetry (DSC) and dynamic light scattering (DLS). According to the result, its experimental pI and optimal pH range were 5.8 and 3.6-4.4, respectively. Design of experiment (DoE) approach was developed as a practical tool to aid formulation studies as a function of pH (2.9-5.7), buffer (phosphate, acetate, citrate, and histidine), and buffer concentration (20 mM and 50 mM). This method employed a weight-based procedure to interpret complex data sets and to investigate critical key factors representing protein stability. The factors used were Tm, enthalpy, and relative helix contents which were obtained by DSC and Fourier Transform Infrared spectroscopy (FT-IR). Although the weights changed by three responses, objective functions from a set of experimental designs based on four buffers were highest in 20 mM acetate buffer at pH 3.6 among all 19 scenarios tested. Size exclusion chromatography (SEC) was adopted to investigate accelerated storage stability in order to optimize the pH value with susceptible stability since the low pH was not patient-compliant. Interestingly, relative helix contents and storage stability (monomer remaining) increased with pH and was the highest at pH 4.0. On the other hand, relative helix contents and thermodynamic stability decreased at pH 4.2 and 4.4, suggesting protein aggregation issues. Therefore, the optimized basal buffer system for the novel biobetter was proposed to be 20 mM acetate buffer at pH 3.8±0.2.

  1. Characterisation of passive films formed on low carbon steel in borate buffer solution (pH 9.2) by electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Hamadou, L.; Kadri, A.; Benbrahim, N.

    2005-12-01

    The comprehension of passivity and its protective character against corrosion is closely connected with the electronic properties of passive films. Passive films formed anodically on carbon steel in borate/boric acid solution, pH 9.2, have been characterised by electrochemical impedance spectroscopy (EIS). Mott-Schottky plots and impedance measurements were made on films formed at different potentials and times. The investigation allowed the determination of the semiconductive properties of the films. The results of the capacitance response indicate that the passive films behave like highly doped n-type semiconductors, showing that the passive film properties are dominated by iron. The value of donors density ( ND) for the passive film is of the order of 10 21 cm -3 and decreases with increasing formation time and potential, indicating that defects decrease with increasing film thickness. Based on the information about the physical phenomena, an equivalent circuit is proposed to fit the experimental data, leading to determination of anodic film capacitance and film resistance.

  2. Effect of royal jelly on experimental colitis induced by acetic acid and alteration of mast cell distribution in the colon of rats

    PubMed Central

    Karaca, T.; Bayiroglu, F.; Yoruk, M.; Kaya, M.S.; Uslu, S.; Comba, B.; Mis, L.

    2010-01-01

    This study investigated the effects of royal jelly (RJ) on acetic acid-induced colitis in rats. Twenty adult female Wistar albino rats were divided into four treatment groups of 5 animals each, including a control group (Group I); Group II was treated orally with RJ (150 mg kg−1 body weight); Group III had acetic acid-induced colitis; and Group IV had acetic acid-induced colitis treated orally with RJ (150 mg kg−1 body weight) for 4 weeks. Colitis was induced by intracolonic instillation of 4% acetic acid; the control group received physiological saline (10 mL kg−1). Colon samples were obtained under deep anaesthesia from animals in all groups. Tissues were fixed in 10% formalin neutral buffer solution for 24 h and embedded in paraffin. Six-micrometre-thick sections were stained with Mallory’s triple stain and toluidine blue in 1% aqueous solution at pH 1.0 for 5 min (for Mast Cells). RJ was shown to protect the colonic mucosa against the injurious effect of acetic acid. Colitis (colonic damage) was confirmed histomorphometrically as significant increases in the number of mast cells (MC) and colonic erosions in rats with acetic acid-induced colitis. The RJ treatment significantly decreased the number of MC and reduced the area of colonic erosion in the colon of RJ-treated rats compared with rats with untreated colitis. The results suggest that oral treatment with RJ could be used to treat colitis. PMID:21263740

  3. Fabrication of organic FETs based on printing techniques and the improvement of FET properties by the insertion of solution-processable buffer layers

    NASA Astrophysics Data System (ADS)

    Itoh, Eiji; Kanamori, Akira

    2016-04-01

    In this study, we developed multilayer deposition and patterning processes that can be used to fabricate all-printed, organic field-effect transistors (OFETs) on the basis of vacuum-free, solution-processable soft-lithography techniques. We have used regioregular poly(3-hexylthiophene) (P3HT) as a soluble p-type polymer semiconductor and (6,6)-phenyl C61 butyric acid methyl ester (PCBM) as a soluble n-type semiconductor, and cross-linked poly(vinyl phenol) (CL-PVP) as a low-temperature (<150 °C)-curable soluble polymer gate insulator. We have compared the electrical properties of OFETs with multiwalled carbon nanotubes (MWCNTs), silver nanoparticles (NPs), and their composites (or multilayers) as printed source-drain (S-D) electrodes in order to fabricate vacuum-free, all-printed OFETs. The P3HT-OFETs with MWCNT S-D electrodes exhibited higher hole mobility and on/off ratios than the devices with Ag NP S-D electrodes owing to better contact at the MWCNT/P3HT interface. On the other hand, Ag/molybdenum oxide (MoO3) S-D electrodes considerably enhanced the hole injection and caused the reduction in the on/off ratio and the difficulty in turning off the devices. The PCBM-OFETs with MWCNT S-D electrodes also exhibited higher electron mobility that is almost comparable to that of P3HT-OFETs and lower threshold voltage, which was considered to be due to the enhanced electron injection at the electrode interface.

  4. Tris-sucrose buffer system: a new specially designed medium for extracellular invertase production by immobilized cells of isolated yeast Cryptococcus laurentii MT-61.

    PubMed

    Aydogan, Mehmet Nuri; Taskin, Mesut; Canli, Ozden; Arslan, Nazli Pinar; Ortucu, Serkan

    2014-01-01

    The aims of the present study were to isolate new yeasts with high extracellular (exo) invertase activity and to investigate the usability of buffer systems as invertase production media by immobilized yeast cells. Among 70 yeast isolates, Cryptococcus laurentii MT-61 had the highest exo-invertase activity. Immobilization of yeast cells was performed using sodium alginate. Higher exo-invertase activity for immobilized cells was achieved in tris-sucrose buffer system (TSBS) compared to sodium acetate buffer system and potassium phosphate buffer system. TSBS was prepared by dissolving 30 g of sucrose in 1 L of tris buffer solution. The optimum pH, temperature, and incubation time for invertase production with immobilized cells were determined as 8.0, 35 °C and 36 h in TSBS, respectively. Under optimized conditions, maximum exo-invertase activity was found to be 28.4 U/mL in sterile and nonsterile TSBS. Immobilized cells could be reused in 14 and 12 successive cycles in sterile and nonsterile TSBS without any loss in the maximum invertase activity, respectively. This is the first report which showed that immobilized microbial cells could be used as a biocatalyst for exo-invertase production in buffer system. As an additional contribution, a new yeast strain with high invertase activity was isolated.

  5. 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.

  6. Electromembrane extraction and HPLC analysis of haloacetic acids and aromatic acetic acids in wastewater.

    PubMed

    Alhooshani, Khalid; Basheer, Chanbasha; Kaur, Jagjit; Gjelstad, Astrid; Rasmussen, Knut E; Pedersen-Bjergaard, Stig; Lee, Hian Kee

    2011-10-30

    For the first time, haloacetic acids and aromatic acetic acids were extracted from wastewater samples using electromembrane extraction (EME). A thin layer of toluene immobilized on the walls of a polypropylene membrane envelope served as an artificial supported liquid membrane (SLM). The haloacetic acids (HAAs) (chloroacetic acid, dichloroacetic acid, and trifluoroacetic acid) and aromatic acetic acids (phenylacetic acid and p-hydroxyphenylacetic acid) were extracted through the SLM and into an alkalized aqueous buffer solution. The buffer solution was located inside the membrane envelope. The electrical potential difference sustained over the membrane acted as the driving force for the transport of haloacetic acids into the membrane by electrokinetic migration. After extraction, the extracts were analyzed by high-performance liquid chromatography-ultraviolet detection. The detection limits were between 0.072 and 40.3 ng L(-1). The calibration plot linearity was in the range of 5 and 200 μg L(-1) while the correlation coefficients for the analytes ranged from 0.9932 to 0.9967. Relative recoveries were in the range of 87-106%. The extraction efficiency was found to be comparable to that of solid-phase extraction.

  7. Tetragonal Chicken Egg White Lysozyme Solubility in Sodium Chloride Solutions

    NASA Technical Reports Server (NTRS)

    Forsythe, Elizabeth L.; Judge, Russell A.; Pusey, Marc L.

    1998-01-01

    The solubility of chicken egg white lysozyme, crystallized in the tetragonal form was measured in sodium chloride solutions from 1.6 to 30.7 C, using a miniature column solubility apparatus. Sodium chloride solution concentrations ranged from 1 to 7% (w/v). The solutions were buffered with 0.1 M sodium acetate buffer with the solubility being measured at pH values in 0.2 pH unit increments in the range pH 4.0 to 5.4, with data also included at pH 4.5. Lysozyme solubility was found to increase with increases in temperature and decreasing salt concentration. Solution pH has a varied and unpredictable effect on solubility.

  8. Conjugation of silica nanoparticles with cellulose acetate/polyethylene glycol 300 membrane for reverse osmosis using MgSO4 solution.

    PubMed

    Sabir, Aneela; Shafiq, Muhammad; Islam, Atif; Jabeen, Faiza; Shafeeq, Amir; Ahmad, Adnan; Zahid Butt, Muhammad Taqi; Jacob, Karl I; Jamil, Tahir

    2016-01-20

    Thermally-induced phase separation (TIPS) method was used to synthesize polymer matrix (PM) membranes for reverse osmosis from cellulose acetate/polyethylene glycol (CA/PEG300) conjugated with silica nanoparticles (SNPs). Experimental data showed that the conjugation of SNPs changed the surface properties as dense and asymmetric composite structure. The results were explicitly determined by the permeability flux and salt rejection efficiency of the PM-SNPs membranes. The effect of SNPs conjugation on MgSO4 salt rejection was more significant in magnitude than on permeation flux i.e. 2.38 L/m(2)h. FTIR verified that SNPs were successfully conjugated on the surface of PM membrane. DSC of PM-SNPs shows an improved Tg from 76.2 to 101.8 °C for PM and PM-S4 respectively. Thermal stability of the PM-SNPs membranes was observed by TGA which was significantly enhanced with the conjugation of SNPs. The micrographs of SEM and AFM showed the morphological changes and increase in the valley and ridges on membrane surface. Experimental data showed that the PM-S4 (0.4 wt% SNPs) membrane has maximum salt rejection capacity and was selected as an optimal membrane.

  9. PVA-based tunable buffering membranes for isoelectric trapping separations.

    PubMed

    Fleisher-Craver, Helen C; Vigh, Gyula

    2008-11-01

    PVA-based buffering membranes with tunable pH values were prepared on a PVA substrate by reacting PVA, glycerol-1,3-diglycidyl ether, -NH2 group-containing buffers and -NH2 group-containing titrants in the presence of sodium hydroxide. The pH of the buffering membranes could be tuned in the 3buffering capacities in excess of 100 mM. Detailed recipes for the preparation of six families of buffering membranes are tabulated and provided as Supporting Information. The buffering membranes were used to trap and desalt ampholyte solutions and separate proteins having a DeltapI as small as 0.1. The membranes were mechanically and hydrolytically stable and could be stored, even in 10solutions, in excess of 6 months.

  10. Resistance of Pseudomonas to Quaternary Ammonium Compounds. I. Growth in Benzalkonium Chloride Solution

    PubMed Central

    Adair, Frank W.; Geftic, Sam G.; Gelzer, Justus

    1969-01-01

    Resistant cells of Pseudomonas aeruginosa and a waterborne Pseudomonas sp. (strain Z-R) were able to multiply in nitrogen-free minimal salts solution containing various concentrations of commercially prepared, ammonium acetate-buffered benzalkonium chloride (CBC), a potent antimicrobial agent. As the CBC concentration increased, growth increased until a point was reached at which the extent of growth leveled off or was completely depressed. Minimal salts solutions of pure benzalkonium chloride (PBC) containing no ammonium acetate did not support bacterial growth. When ammonium acetate was added to PBC solutions in the same concentrations found in CBC solutions, growth patterns developed that were comparable to those found with CBC. Likewise, (NH4)2SO4 added to PBC solutions supported growth of both organisms. P. aeruginosa was initially resistant to CBC levels of 0.02% and it was adapted to tolerate levels as high as 0.36%. Strain Z-R was naturally resistant to 0.4% CBC. Since ammonium acetate, carried over by the CBC used in drug formulations and disinfectant solutions, has the potential to support the growth of resistant bacteria and thus make possible the risk of serious infection, it is suggested that regulations allowing the presence of ammonium acetate in CBC solution be reconsidered. PMID:4984761

  11. Sustained in vivo activity of recombinant bovine granulocyte colony stimulating factor (rbG-CSF) using HEPES buffer.

    PubMed

    Kasraian, K; Kuzniar, A; Earley, D; Kamicker, B J; Wilson, G; Manion, T; Hong, J; Reiber, C; Canning, P

    2001-08-01

    The purpose of this study was to develop a long-acting injectable formulation of bG-CSF for veterinary use. However, in order to achieve sustained in vivo activity it was first necessary to stabilize the protein at the injection site. Preformulation studies, as well as literature, suggest that bG-CSF aggregates at neutral pH ranges (i.e., pH 6-8) and at temperatures of approximately 40 degrees C. Therefore, bG-CSF will not retain its activity for an extended period of time at the injection site. During this study we determined that HEPES buffer has a very significant impact on protein stability as well as on biological performance. Recombinant bovine granulocyte colony stimulating factor (rbG-CSF) was formulated in 1 M HEPES buffer for subcutaneous injection into cows. bG-CSF formulated in 1 M HEPES buffer resulted in sustained in vivo activity of bG-CSF compared to the "control" formulation (control formulation: 5% mannitol, 10 mM acetate buffer, 0.004% tween-80, pH 4). White blood cell (WBC) count was used as a marker to evaluate in vivo activity of the formulation. WBC numbers remained above a threshold value for only 24-30 h for the control formula. However, when bG-CSF was formulated in 1 M HEPES, the WBC remained above threshold for 3 days or 72 h. Formulating bG-CSF in 1 M HEPES at pH 7.5 also resulted in greater solution stability. This was surprising since bG-CSF is intrinsically not stable at neutral pH. The effect of 1 M HEPES on the T(M) (temperature at maximum heat flow on calorimetry scan) of bG-CSF was determined by microcalorimetry. In the absence of 1 M HEPES buffer the T(M) was 48 degrees C (onset approximately 40 degrees C), while bG-CSF formulated in 1 M HEPES buffer has a T(M) of 59 degrees C (onset approximately 50 degrees C). Similar organic buffers, such as MOPS, HEPPS, TES, and tricine, also resulted in improved solution stability as well as in sustained in vivo activity. The dramatic effect of these buffers on stability and biological

  12. Cellulose acetate electrospun fiber mats for controlled release of silymarin.

    PubMed

    Phiriyawirut, Manisara; Phaechamud, Thawatchai

    2012-01-01

    In this research, the silymarin-loaded electrospun cellulose acetate (CA) fibers were prepared which containing silymarin in various amounts (i.e., 2.5-20 wt.% based on the weight of CA powder). Incorporation of silymarin in the neat CA solution did not affect the morphology of the resulting fibers, as both the neat and the silymarin-loaded CA fibers were smooth. The average diameters of silymarin-loaded CA fiber ranged between 550-900 nm. No presence of the silymarin aggregates of any kind was observed on the surfaces of these fibers, suggesting that the silymarin was encapsulated well within the fibers. These results were confirmed by lowering the glass transition temperature and the melting temperature of the silymarin-loaded electrospun CA fibers which is determined by DSC technique. The release characteristic of silymarin from the silymarin-loaded CA fiber mats was investigated by the total immersion in the solution of 1/1 phosphate buffer/methanol medium pH 7.4 at 37 degrees C. The silymarin release from the silymarin-loaded electrospun CA fiber mat is monotonously increased to reach the maximum value at 480 min. The maximum amount of silymarin released from these materials increases with the increasing of initial silymarin loading in the spinning CA solutions. Since no aggregation of silymarin was found on the surface of the silymarin-loaded fibers, the release of the silymarin from fiber mats was mainly by the diffusion.

  13. The physicochemical property characterization of agar acetate.

    PubMed

    Xia, Kai; Liu, Xin; Zhao, Jingkun; Zhang, Xiaodong

    2014-09-22

    A series of agar acetates with different degree of substitution (DS) were prepared, and their properties were determined and analyzed. The results showed that the gelling temperature, the gel melting temperature, the gel strength, the gel hardness, the gel fracturability, the gel springiness and the solution apparent viscosity of agar acetates all decreased except that their gel cohesiveness increased with the increase of DS. The variation process of agar molecules in solution from coil to helix could be also observed by measuring solution optical rotation in a lower concentration at which even the solution could not form a gel. The gel skeleton structures of agar acetates were of porous network structures, and the pores became smaller and denser with the increase of DS. After acetylation, the water holding capacity of the agar was improved, but its thermal stability was lowered.

  14. Zebrafish as a Model for Systems Medicine R&D: Rethinking the Metabolic Effects of Carrier Solvents and Culture Buffers Determined by (1)H NMR Metabolomics.

    PubMed

    Akhtar, Muhammad T; Mushtaq, Mian Y; Verpoorte, Robert; Richardson, Michael K; Choi, Young H

    2016-01-01

    Zebrafish is a frequently employed model organism in systems medicine and biomarker discovery. A crosscutting fundamental question, and one that has been overlooked in the field, is the "system-wide" (omics) effects induced in zebrafish by metabolic solvents and culture buffers. Indeed, any bioactivity or toxicity test requires that the target compounds are dissolved in an appropriate nonpolar solvent or aqueous media. It is important to know whether the solvent or the buffer itself has an effect on the zebrafish model organism. We evaluated the effects of two organic carrier solvents used in research with zebrafish, as well as in drug screening: dimethyl sulfoxide (DMSO) and ethanol, and two commonly used aqueous buffers (egg water and Hank's balanced salt solution). The effects of three concentrations (0.01, 0.1, and 1%) of DMSO and ethanol were tested in the 5-day-old zebrafish embryo using proton nuclear magnetic resonance ((1)H NMR) based metabolomics. DMSO (1% and 0.1%, but not 0.01%) exposure significantly decreased the levels of adenosine triphosphate (ATP), betaine, alanine, histidine, lactate, acetate, and creatine (p < 0.05). By contrast, ethanol exposure did not alter the embryos' metabolome at any concentration tested. The two different aqueous media noted above impacted the zebrafish embryo metabolome as evidenced by changes in valine, alanine, lactate, acetate, betaine, glycine, glutamate, adenosine triphosphate, and histidine. These results show that DMSO has greater effects on the embryo metabolome than ethanol, and thus is used with caution as a carrier solvent in zebrafish biomarker research and oral medicine. Moreover, the DMSO concentration should not be higher than 0.01%. Careful attention is also warranted for the use of the buffers egg water and Hank's balanced salt solution in zebrafish. In conclusion, as zebrafish is widely used as a model organism in life sciences, metabolome changes induced by solvents and culture buffers warrant further

  15. The biocompatibility of titanium in a buffer solution: compared effects of a thin film of TiO2 deposited by MOCVD and of collagen deposited from a gel.

    PubMed

    Popescu, Simona; Demetrescu, Ioana; Sarantopoulos, Christos; Gleizes, Alain N; Iordachescu, Dana

    2007-10-01

    This study aims at evaluating the biocompatibility of titanium surfaces modified according two different ways: (i) deposition of a bio-inert, thin film of rutile TiO(2) by chemical vapour deposition (MOCVD), and (ii) biochemical treatment with collagen gel, in order to obtain a bio-interactive coating. Behind the comparison is the idea that either the bio-inert or the bio-active coating has specific advantages when applied to implant treatment, such as the low price of the collagen treatment for instance. The stability in buffer solution was evaluated by open circuit potential (OCP) for medium time and cyclic voltametry. The OCP stabilized after 5.10(4) min for all the specimens except the collagen treated sample which presented a stable OCP from the first minutes. MOCVD treated samples stabilized to more electropositive values. Numeric results were statistically analysed to obtain the regression equations for long time predictable evolution. The corrosion parameters determined from cyclic curves revealed that the MOCVD treatment is an efficient way to improve corrosion resistance. Human dermal fibroblasts were selected for cell culture tests, taking into account that these cells are present in all bio-interfaces, being the main cellular type of connective tissue. The cells grew on either type of surface without phenotype modification. From the reduction of yellow, water-soluble 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT cytotoxicity test), MOCVD treated samples offer better viability than mechanically polished Ti and collagen treated samples as well. Cell spreading, as evaluated from microscope images processed by the program Sigma Scan, showed also enhancement upon surface modification. Depending on the experimental conditions, MOCVD deposited TiO(2) exhibits different nanostructures that may influence biological behaviour. The results demonstrate the capacity of integration in simulated physiologic liquids for an implant pretreated by

  16. Preparation of vinyl acetate

    DOEpatents

    Tustin, Gerald Charles; Zoeller, Joseph Robert; Depew, Leslie Sharon

    1998-01-01

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  17. Preparation of vinyl acetate

    DOEpatents

    Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

    1998-03-24

    This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

  18. Effect of passivation on the dissolution behavior of Ti6A14V and vacuum-brazed Ti6A14V in Hank's ethylene diamine tetra-acetic acid solution Part I Ion release.

    PubMed

    Lee, T M; Chang, E; Yang, C Y

    1999-09-01

    This work aims to investigate the effects of three factors, namely: (1) two differently prepared materials (as-polished Ti6A14V and 2 h brazed Ti6A14V); (2) three different surface passivation treatments (34% nitric acid passivation, 400 degrees C heated in air, and aged in 100 degrees C de-ionized water); and (3) periods of immersion time (up to 32 days), on trace element release in Hank's ethylene diamine tetra-acetic acid (EDTA) solution. After passivation and autoclaving treatment, the specimens were immersed in 8.0 mM EDTA in Hank's solution and maintained at 37 degrees C for periods of time up to 32 days. The 400 degrees C -treated specimens exhibit a substantial reduction in constituent release, which may be attributed to the higher thickness and rutile structure of the surface oxides. For acid-passivated and water-aged treatments, a highly significant decrease in the trace levels of Ti, A1, and V is detected from the brazed Ti6A14V compared to those obtained from the Ti6A14V specimens. It is hypothesized that an anatase-rutile transformation of surface TiO_2 is likely to occur, accelerated by the elements of copper and nickel in the brazed specimens. In addition, a significant time-related decrease in constituent release rate is observed for all kinds of specimens throughout the 0-8 day experimental period. The implication of the results is discussed.

  19. Liquid Chromatography-Tandem Mass Spectrometry for Analysis of Intestinal Permeability of Loperamide in Physiological Buffer

    PubMed Central

    Rubelt, Miriam S.; Amasheh, Salah; Grobosch, Thomas; Stein, Christoph

    2012-01-01

    Analysis of in vitro samples with high salt concentrations represents a major challenge for fast and specific quantification with liquid chromatography-tandem mass spectrometry (LC-MS/MS). To investigate the intestinal permeability of opioids in vitro employing the Ussing chamber technique, we developed and validated a fast, sensitive and selective method based on LC–MS/MS for the determination of loperamide in HEPES-buffered Ringer's solution. Chromatographic separation was achieved with an Atlantis dC18 column, 2.1 mm×20 mm, 3 µm particle size and a gradient consisting of methanol/0.1% formic acid and ammonium acetate. The flow rate was 0.7 ml/min, and the total run time was 3 min. For quantification, two mass transitions for loperamide and a deuterated internal standard (methadone-d3) were used. The lower limit of loperamide quantification was 0.2 ng/ml. This new LC-MS/MS method can be used for the detection of loperamide in any experimental setup using HEPES-buffered Ringer's solution as a matrix compound. PMID:23144895

  20. 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

  1. Effect of Ethylene diamine tetra acetic acid and sodium hypochlorite solution conditioning on microtensile bond strength of one-step self-etch adhesives

    PubMed Central

    Kasraei, Shahin; Azarsina, Mohadese; Khamverdi, Zahra

    2013-01-01

    Background: Attempts to improve bond strength of self-etch adhesives can enhance the durability of composite restorations. Aims: The aim of the present study was to evaluate the effect of collagen and smear layer removal with sodium hypochlorite solution (NaOCl) and EDTA on micro-tensile bond strength (μTBS) of self-etch adhesives to dentin. Settings and Design: It was an in-vitro study. Materials and Methods: Seventy-two teeth were divided into eight groups and their crowns were ground perpendicular to their long axis to expose dentin. The teeth were polished with silicon-carbide papers. The groups were treated as follows: No conditioning, 0.5-M EDTA conditioning, 2.5% NaOCl conditioning, NaOCl + EDTA conditioning. The surfaces were rinsed and blot-dried. Clearfil S3 and I-Bond were applied according to manufacturers’ instructions and restored with Z100 composite. After 500 cycles of thermo-cycling between 5°C and 55°C, the samples were sectioned and tested for μTBS. Statistical Analysis: Data were analyzed by two-way ANOVA and Tukey-HSD test. Results: The highest μTBS was recorded with Clearfil S3 + NaOCl + EDTA, and the lowest was recorded with I-Bond without conditioning. μTBS in EDTA-and EDTA + NaOCl-treated groups was significantly higher than the control and NaOCl-conditioned groups. Conclusions: Application of EDTA or EDTA + NaOCl before one-step self-etch adhesives increased μTBS. PMID:23833459

  2. Is bicarbonate buffer suitable as a dissolution medium?

    PubMed

    Boni, Julia Elisabeth; Brickl, Rolf Stefan; Dressman, Jennifer

    2007-10-01

    The objectives of this study were to compare two methods for the preparation of bicarbonate buffer, and to compare media prepared with bicarbonate buffer with commonly used biorelevant and pharmacopoeial media in terms of their suitability for dissolution testing. The various media were compared with regard to ease of preparation, robustness and reproducibility of composition. The dissolution of three formulations of a typical Biopharmaceutical Classification System Class II drug (BIXX) was compared in bicarbonate buffer, standard phosphate buffer, a biorelevant buffer (fasted-state simulating intestinal fluid, FaSSIF) and a modified FaSSIF prepared with bicarbonate buffer. The bicarbonate buffer used for dissolution testing was produced by supplying carbon dioxide to a saline solution (0.9% NaCl, to which 12 or 42 mmol NaOH had been added). The bicarbonate buffer had to be prepared in-situ, which proved to be time-consuming, and the pH stability of the bicarbonate buffer could only be maintained under constant CO2 supply. To minimize the mechanical stress caused by inflow and evaporation of gas, the carbon dioxide was supplied above the medium during the dissolution test. Despite taking these measures, use of bicarbonate buffer led to less reproducible dissolution results than the phosphate buffers commonly used to prepare compendial media and FaSSIF, with coefficient of variance values 1.5- to 5-times higher in bicarbonate buffer. It was concluded that although a bicarbonate buffer system would be physiologically relevant for the fasted state in the small intestine, its suitability for dissolution testing is restricted by lack of practicability and poor reproducibility of results.

  3. Nanofabrication in cellulose acetate.

    PubMed

    Zeng, Hongjun; Lajos, Robert; Metlushko, Vitali; Elzy, Ed; An, Se Young; Sautner, Joshua

    2009-03-07

    We have demonstrated nanofabrication with commercialized cellulose acetate. Cellulose acetate is used for bulk nanofabrication and surface nanofabrication. In bulk nanofabrication, cellulose acetate reacts with an e-beam and permanent patterns are formed in it instead of being transferred to other substrates. We have studied the nano relief modulation performance of cellulose acetate before and after development. The depth of the nanopatterns is magnified after development, and is varied by exposing dosage and line width of the pattern. The thinnest 65 nm wide line is achieved in the bulk fabrication. We also demonstrate a binary phase Fresnel lens array which is directly patterned in a cellulose acetate sheet. Because of its unique mechanical and optical properties, cellulose is a good candidate for a template material for soft imprinting lithography. In the surface nanofabrication, cellulose acetate thin film spin-coated on silicon wafers is employed as a new resist for e-beam lithography. We achieved 50 nm lines with 100 nm pitches, dots 50 nm in diameter, and single lines with the smallest width of 20 nm. As a new resist of e-beam lithography, cellulose acetate has high resolution comparable with conventional resists, while having several advantages such as low cost, long stock time and less harmfulness to human health.

  4. Adsorption behavior of ferritin and buffer components, buffer agents and salts, onto silane-coupled silicon substrate.

    PubMed

    Fukuta, Megumi; Yamashita, Ichiro

    2010-01-01

    Fixation of ferritin using amino-silane modified substrates is effective, but salt and alkali ions of the buffer can contaminate substrates, inhibiting the sensing and fabrication of nano-electronic devices. To avoid adsorption of salts and alkali ions, buffer solutions have been replaced by pure water or alkali-metal-ion-free buffer. However, proteins in such solutions are sometimes denatured. Therefore, we developed a substrate which adsorbs ferritin but does not adsorb contaminants such as salts and alkali metal-ions contained in the buffer. Adsorption of ferritin was achieved by using a buffer with a high ion strength, such as PBS buffer, because the Debye length becomes shorter with increased ion strength due to intermolecular force even when the substrate has no positive charge. The combination of high coverage methyltrimethoxysilane (MTMS)-coupled silicon substrate and PBS buffer solution is effective for adsorption of ferritin while not adsorbing buffer components such as contaminants and/or salts on the silicon substrate.

  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.

  6. 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.

  7. Liquid growth hormone: preservatives and buffers.

    PubMed

    Kappelgaard, Anne-Marie; Bojesen, Anders; Skydsgaard, Karsten; Sjögren, Ingrid; Laursen, Torben

    2004-01-01

    alcohol. Furthermore, patients reported more pain following injection of a citrate-buffered solution than after a histidine-buffered solution. More pain was also reported following large volume injections and following injections with solutions containing high protein concentrations. In summary, optimization of the preservative and buffer content of a liquid GH formulation may reduce injection pain and lead to improved patient compliance.

  8. A Study of Bonding Cellulose Acetate to Polyarylsulfone,

    DTIC Science & Technology

    The objective of this study was to develop a method by which ultrathin films (500 to 1500 angstroms in thickness) of cellulose acetate could be...rejecting and flow characteristics of the cellulose acetate -polysulfone composite. A successful method was found to be the application of a dilute...solution (1.5 percent by weight) of Resyn 26-2404 to the polysulfone before casting the cellulose acetate membrane. A TYPICAL COMPOSITE WITH A SPRAYED

  9. Effects of Buffer Loading for Electrospray Ionization Mass Spectrometry of a Noncovalent Protein Complex that Requires High Concentrations of Essential Salts

    PubMed Central

    Sterling, Harry J.; Batchelor, Joseph D.; Wemmer, David E.; Williams, Evan R.

    2010-01-01

    Electrospray ionization (ESI) mass spectrometry (MS) is a powerful method for analyzing the active forms of macromolecular complexes of biomolecules. However, these solutions often contain high concentrations of salts and/or detergents that adversely effect ESI performance by making ion formation less reproducible, causing severe adduction or ion suppression. Many methods for separating complexes from nonvolatile additives are routinely used with ESI-MS, but these methods may not be appropriate for complexes that require such stabilizers for activity. Here, the effects of buffer loading using concentrations of ammonium acetate ranging from 0.22 to 1.41 M on the ESI mass spectra of a solution containing a domain truncation mutant of a σ54 activator from Aquifex aeolicus were studied. This 44.9 kDa protein requires the presence of millimolar concentrations of Mg2+, BeF3−, and ADP, (at ∼60 °C) to assemble into an active homo-hexamer. Addition of ammonium acetate can improve signal stability and reproducibility, and can significantly lower adduction and background signals. However, at higher concentrations, the relative ion abundance of the hexamer is diminished, while that of the constituent monomer is enhanced. These results are consistent with loss of enzymatic activity as measured by ATP hydrolysis and indicate that the high concentration of ammonium acetate interferes with assembly of the hexamer. This shows that buffer loading with ammonium acetate is effective for obtaining ESI signal for complexes that require high concentrations of essential salts, but can interfere with formation of, and/or destabilize complexes by disrupting crucial electrostatic interactions at high concentration. PMID:20226685

  10. Acetate enhances the chemosensory response to hypoxia in the cat carotid body in vitro in the absence of CO2-HCO3-.

    PubMed

    Iturriaga, R

    1996-01-01

    To determine if intracellular acidosis enhances hypoxic chemoreception in the absence of CO2-HCO3- at pH 7.4, the effects of sodium acetate (30 mM) were studied on the chemosensory responses of the cat carotid body to hypoxic, stagnant and cytotoxic hypoxia. Carotid bodies were perfused and superfused in vitro with Tyrode's solution, free of CO2-HCO3-, buffered with HEPES-NaOH, pH 7.40, at 36.5 +/d- 0.5 degrees C and equilibrated at PO2 of 125 Torr (perfusate) and < 20 Torr (superfusate). In the absence of acetate, hypoxia (PO2 25 Torr), flow interruption and NaCN (0.01-100 micrograms) augmented the chemosensory discharges. However, in the presence of acetate, the half-excitation time of these responses decreased and their amplitude increased. Thus, acetate enhances the chemosensory response to hypoxic, stagnant and cytotoxic hypoxia. It is suggested that that intracellular acidosis induced by acetate contributes to this potentiation by correcting the alkaline pHi caused by the absence of HCO3-(-)HCO2 in the perfusate.

  11. Variation of power generation at different buffer types and conductivities in single chamber microbial fuel cells.

    PubMed

    Nam, Joo-Youn; Kim, Hyun-Woo; Lim, Kyeong-Ho; Shin, Hang-Sik; Logan, Bruce E

    2010-01-15

    Microbial fuel cells (MFCs) are operated with solutions containing various chemical species required for the growth of electrochemically active microorganisms including nutrients and vitamins, substrates, and chemical buffers. Many different buffers are used in laboratory media, but the effects of these buffers and their inherent electrolyte conductivities have not been examined relative to current generation in MFCs. We investigated the effect of several common buffers (phosphate, MES, HEPES, and PIPES) on power production in single chambered MFCs compared to a non-buffered control. At the same concentrations the buffers produced different solution conductivities which resulted in different ohmic resistances and power densities. Increasing the solution conductivities to the same values using NaCl produced comparable power densities for all buffers. Very large increases in conductivity resulted in a rapid voltage drop at high current densities. Our results suggest that solution conductivity at a specific pH for each buffer is more important in MFC studies than the buffer itself given relatively constant pH conditions. Based on our analysis of internal resistance and a set neutral pH, phosphate and PIPES are the most useful buffers of those examined here because pH was maintained close to the pK(a) of the buffer, maximizing the ability of the buffer to contribute to increase current generation at high power densities.

  12. 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.

  13. Buffering capacity of the chief components of nutritive media for algae.

    PubMed

    Lívanský, K

    1982-01-01

    The buffering capacity of solutions of KH2PO4 and NaHCO3 increases with their concentration, the behaviour being describable by mathematical expressions. Solutions of KH2PO4 prepared from tap water exhibit a buffering capacity higher by an order of magnitude than those prepared from distilled water. However, there is no difference between the buffering capacities of solutions of NaHCO3 prepared from tap and distilled water. Urea and NH4NO3 have almost no effect on the buffering capacities of solutions.

  14. Fatal Hemorrhagic Shock and Acetate Solutions.

    DTIC Science & Technology

    1984-08-01

    trauma victims occur within 1 hourvOf injury and are due to rapid hemorrhage or CNS trauma . We developed a rapid hemorrhage model in unanesthetized swine...UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGErmUen Data Enteed) q g ABSTRACT One-half of deaths among trauma victims occur within 1 hour of injury and...are due to rapid hemorrhage or CNS trauma . We developed a rapid hemorrhage model in unanesthetized swine to simulate human exsanguination. We compared

  15. 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.

  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. Mechanisms of buffer therapy resistance.

    PubMed

    Bailey, Kate M; Wojtkowiak, Jonathan W; Cornnell, Heather H; Ribeiro, Maria C; Balagurunathan, Yoganand; Hashim, Arig Ibrahim; Gillies, Robert J

    2014-04-01

    Many studies have shown that the acidity of solid tumors contributes to local invasion and metastasis. Oral pH buffers can specifically neutralize the acidic pH of tumors and reduce the incidence of local invasion and metastatic formation in multiple murine models. However, this effect is not universal as we have previously observed that metastasis is not inhibited by buffers in some tumor models, regardless of buffer used. B16-F10 (murine melanoma), LL/2 (murine lung) and HCT116 (human colon) tumors are resistant to treatment with lysine buffer therapy, whereas metastasis is potently inhibited by lysine buffers in MDA-MB-231 (human breast) and PC3M (human prostate) tumors. In the current work, we confirmed that sensitive cells utilized a pH-dependent mechanism for successful metastasis supported by a highly glycolytic phenotype that acidifies the local tumor microenvironment resulting in morphological changes. In contrast, buffer-resistant cell lines exhibited a pH-independent metastatic mechanism involving constitutive secretion of matrix degrading proteases without elevated glycolysis. These results have identified two distinct mechanisms of experimental metastasis, one of which is pH-dependent (buffer therapy sensitive cells) and one which is pH-independent (buffer therapy resistant cells). Further characterization of these models has potential for therapeutic benefit.

  19. ITC Methods for Assessing Buffer/Protein Interactions from the Perturbation of Steady-State Kinetics: A Reactivity Study of Homoprotocatechuate 2,3-Dioxygenase.

    PubMed

    Henderson, Kate L; Boyles, Delta K; Le, Vu H; Lewis, Edwin A; Emerson, Joseph P

    2016-01-01

    Isothermal titration calorimetry (ITC) can be used to study the thermodynamics of enzyme substrate binding or the kinetics of substrate turnover (or both). Substrate-binding interactions are observed in a typical ITC titration experiment in which the heat change for the addition of an aliquot of substrate to a solution containing the enzyme is determined for a number of titrant (i.e., substrate) injections and the data fit for the thermodynamic parameters (ΔG, ΔH, and -TΔS) for substrate binding. Of course, these measurements must be made under conditions where the substrate binds but does not turnover. In the ITC "kinetics" experiment, the power change observed after injection of an excess of substrate into a solution of the enzyme is a direct measure of the rate at which substrate is converted to product, and the ITC data can be analyzed for the kinetic parameters (Vmax, kcat, KM, and kcat/KM). The ITC technique is particularly versatile in that it can be applied to systems where there might not be a change in a spectroscopic signal for either substrate binding or the reaction of the substrate to form product. A complication is that if there are competing reactions, for example, buffer protonation, or product binding, to name just two, the enthalpy change measured for either substrate binding or for substrate turnover will be a summation of all of the reaction heats. Enzyme studies are typically done in buffered solutions at constant pH. The general, and often incorrect, assumption is that the buffer components are simply spectators and not participants in either substrate binding or substrate turnover. This chapter describes how we have used ITC measurements to identify problem buffers that impact the kinetics for an enzyme catalyzed reaction. Herein, we show the effects of several buffers on the steady-state kinetics for the conversion of the substrate, 3,4-dihydroxyphenyl acetate (homoprotocatechuate), to the ring-opened product, 5-carboxymethyl-2

  20. 1,3,5-Tris(phenyl-2-benzimidazole)-benzene cathode buffer layer thickness dependence in solution-processable organic solar cell based on 1,4,8,11,15,18,22,25-octahexylphthalocyanine

    NASA Astrophysics Data System (ADS)

    De Roméo Banoukepa, Gilles; Fujii, Akihiko; Shimizu, Yo; Ozaki, Masanori

    2015-04-01

    Studies on the insertion effects of a cathode buffer layer on bulk heterojunction organic solar cell based on 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) and 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C61 (PCBM) by using 1,3,5-tris(phenyl-2-benzimidazole)-benzene (TPBi) as a cathode buffer layer material have been carried out. The external quantum efficiency and the short-circuit current markedly increased, resulting in the enhancement of the power conversion efficiency. The solar cell performance has been discussed from the atomic force microscopy, photoelectron yield spectroscopy and X-ray photoelectron spectroscopy measurements.

  1. Thermal decomposition of acetate: III. Catalysis by mineral surfaces

    NASA Astrophysics Data System (ADS)

    Bell, Julie L. S.; Palmer, Donald A.; Barnes, H. L.; Drummond, S. E.

    1994-10-01

    The kinetics of thermal decarboxylation of aqueous solutions of acetic acid and sodium acetate were evaluated at 335 and 355°C in contact with various surfaces as potential catalysts. Quartz, fused quartz, calcite, natural pyrite, titanium oxide, and Au apparently do not catalyze aqueous decarboxylation reactions, in contrast to Pyrex, Ca-montmorillonite, Fe-bearing montmorillonite, hematite, synthetic pyrite, and magnetite. The dependence of the rate of acetic acid decarboxylation on the surface area of pyrite per unit solution volume was also studied. The results show that the decarboxylation of acetic acid and acetate is catalyzed heterogeneously, with the cleavage of the C-C bond occurring while the acetate molecule is adsorbed onto a surface. Entropies and enthalpies of activation obtained from these experiments are compatible with the isokinetic relationship established previously for acetic acid and acetate under similar experimental conditions, indicating the existence of a common rate-determining step. Experimental evidence indicates that oxidation of acetic acid can occur with hematite and defected magnetite. These oxidative decomposition reactions differ from the decarboxylation reaction in that CO 2 and polycondensates are produced instead of CO 2 and CH 4.

  2. Determination of the constants of affinity of FeCl3, CuCl2, and ZnCl2 for a nitrogen-containing organosilane bonded on Al2O3-cellulose acetate hybrid material surface from ethanol solution.

    PubMed

    Lazarin, Angélica M; Landers, Richard; Kholin, Yuriy V; Gushikem, Yoshitaka

    2002-10-01

    This work describes the preparation and characterization of a cellulose acetate fiber coated with Al(2)O(3), resulting in the organic-inorganic hybrid Cel/Al(2)O(3). Furthermore, the hybrid was modified by attaching organofunctional groups by reaction with the precursor reagents (RO)(3)Si(CH(2))(3)L (L=NH(2), NH(CH(2))(2)NH(2), NH(CH(2))(2)NH(CH(2))(2)NH(2), and N(2)C(3)H(3) (imidazole)), resulting in Cel/Al(2)O(3)/Si(CH(2))(3)NH(2) (1), Cel/Al(2)O(3)/Si(CH(2))(3)NH(CH(2))(2)NH(2) (2), Cel/Al(2)O(3)/Si(CH(2))(3)NH(CH(2))(2)NH(CH(2))(2)NH(2) (3), and Cel/Al(2)O(3)/Si(CH(2))(3)N(2)C(3)H(3) (4). The amounts of attached organofunctional groups were (in mmol per gram of the material) 1=1.90, 2=1.89, 3=1.66, and 4=1.35. The isotherms of adsorption of FeCl(3), CuCl(2), and ZnCl(2) by Cel/Al(2)O(3)/Si(CH(2))(3)L from ethanol solutions were obtained at 298 K. Accurate estimates of the specific sorption capacities and the heteregeneous stability constants of the immobilized metal complexes were determined with the aid of several computational procedures. It is shown that the sorptional capacities are much less than the concentrations of the attached organofunctional groups. As all sorption isotherms are fitted properly with the Langmuir isotherm equation, the effects of the energetic heterogeneity and the lateral interactions do not affect the chemisorption equilibria. The heterogeneous stability constants of the immobilized complexes are fairly high, which provides efficient removal of the metal ions from solutions by the hybrid materials.

  3. Doped with Sodium Acetate and Metallic Sodium

    NASA Astrophysics Data System (ADS)

    Tada, Satoki; Isoda, Yukihiro; Udono, Haruhiko; Fujiu, Hirofumi; Kumagai, Shunji; Shinohara, Yoshikazu

    2014-06-01

    We have investigated the thermoelectric properties of p-type Na-doped Mg2 Si0.25Sn0.75 solid solutions prepared by liquid-solid reaction and hot-pressing methods. Na was introduced into Mg2Si0.25Sn0.75 by using either sodium acetate (CH3COONa) or metallic sodium (2 N). The samples doped with sodium acetate consisted of phases with antifluorite structure and a small amount of MgO as revealed by x-ray diffraction, whereas the sample doped with metallic sodium contained the Sn, MgO, and Mg2SiSn phases. The hole concentrations of Mg1.975Na0.025Si0.25Sn0.75 doped by sodium acetate and metallic sodium were 1.84 × 1025 m-3 and 1.22 × 1025 m-3, respectively, resulting in resistivities of 4.96 × 10-5 Ω m (sodium acetate) and 1.09 × 10-5 Ω m (metallic sodium). The Seebeck coefficients were 198 μV K-1 (sodium acetate) and 241 μV K-1 (metallic sodium). The figures of merit for Mg1.975Na0.025Si0.25Sn0.75 were 0.40 × 10-3 K-1 (sodium acetate) and 0.25 × 10-3 K-1 (metallic sodium) at 400 K. Thus, sodium acetate is a suitable Na dopant for Mg2Si1- x Sn x .

  4. Specific ion and buffer effects on protein-protein interactions of a monoclonal antibody.

    PubMed

    Roberts, D; Keeling, R; Tracka, M; van der Walle, C F; Uddin, S; Warwicker, J; Curtis, R

    2015-01-05

    Better predictive ability of salt and buffer effects on protein-protein interactions requires separating out contributions due to ionic screening, protein charge neutralization by ion binding, and salting-in(out) behavior. We have carried out a systematic study by measuring protein-protein interactions for a monoclonal antibody over an ionic strength range of 25 to 525 mM at 4 pH values (5, 6.5, 8, and 9) in solutions containing sodium chloride, calcium chloride, sodium sulfate, or sodium thiocyante. The salt ions are chosen so as to represent a range of affinities for protein charged and noncharged groups. The results are compared to effects of various buffers including acetate, citrate, phosphate, histidine, succinate, or tris. In low ionic strength solutions, anion binding affinity is reflected by the ability to reduce protein-protein repulsion, which follows the order thiocyanate > sulfate > chloride. The sulfate specific effect is screened at the same ionic strength required to screen the pH dependence of protein-protein interactions indicating sulfate binding only neutralizes protein charged groups. Thiocyanate specific effects occur over a larger ionic strength range reflecting adsorption to charged and noncharged regions of the protein. The latter leads to salting-in behavior and, at low pH, a nonmonotonic interaction profile with respect to sodium thiocyanate concentration. The effects of thiocyanate can not be rationalized in terms of only neutralizing double layer forces indicating the presence of an additional short-ranged protein-protein attraction at moderate ionic strength. Conversely, buffer specific effects can be explained through a charge neutralization mechanism, where buffers with greater valency are more effective at reducing double layer forces at low pH. Citrate binding at pH 6.5 leads to protein charge inversion and the formation of attractive electrostatic interactions. Throughout the report, we highlight similarities in the measured

  5. Explanation for the enhanced dissolution of silica column packing in high pH phosphate and carbonate buffers.

    PubMed

    Tindall, G W; Perry, R L

    2003-02-28

    It has been reported that at high pH, the rate of bonded phase packing degradation in methanol/water mobile phases is greater for carbonate and phosphate buffers than for amine buffers. This conclusion was based on buffer pH determined in the aqueous buffer before dilution with methanol. Changes in buffer species pKa, and therefore buffer pH, upon methanol dilution are consistent with the observed degradation results. Measurements of pH in the methanol/water solutions confirm that the carbonate and phosphate buffers were considerably more basic than the amine buffer, even though all the buffers were pH 10 before dilution with methanol. These results demonstrate that it can be misleading to extrapolate aqueous pH data to partially aqueous solutions. Measurements of pH in the mixed solvent provide more reliable predictions of column and sample stability.

  6. High-flux cellulose acetate membranes

    SciTech Connect

    Boeddeker, K.W.; Finken, H.; Wenzlaff, A.

    1981-01-01

    Three routes to increase the permeate flux of asymmetric cellulose diacetate membranes of the Loeb-Sourirajan type were investigated: increasing the hydrophilicity of the membranes; increasing their compaction stability, and employing a swelling agent which allows for higher solvent-to-polymer ratio in the casting solution. The effect of casting solution composition on flux and rejection of formamide-modified cellulose acetate membrane is included, illustrating the general capability of this membrane type as function of solvent concentration. Membranes of casting solution composition cellulose diacetate/acetone/formamide 23/52/25 were used as reference membranes in the work. 6 figures. (DP)

  7. Tau Aggregation Propensity Engrained in Its Solution State.

    PubMed

    Eschmann, Neil A; Do, Thanh D; LaPointe, Nichole E; Shea, Joan-Emma; Feinstein, Stuart C; Bowers, Michael T; Han, Songi

    2015-11-12

    A peptide fragment of the human tau protein which stacks to form neat cross β-sheet fibrils, resembling that found in pathological aggregation, (273)GKVQIINKKLDL(284) (here "R2/WT"), was modified with a spin-label at the N-terminus. With the resulting peptide, R2/G273C-SL, we probed events at time scales spanning seconds to hours after aggregation is initiated using transmission electron microscopy (TEM), thioflavin T (THT) fluorescence, ion mobility mass spectrometry (IMMS), electron paramagnetic resonance (EPR), and Overhauser dynamic nuclear polarization (ODNP) to determine if deliberate changes to its conformational states and population in solution influence downstream propensity to form fibrillar aggregates. We find varying solution conditions by adding the osmolyte urea or TMAO, or simply using different buffers (acetate buffer, phosphate buffer, or water), produces significant differences in early monomer/dimer populations and conformations. Crucially, these characteristics of the peptide in solution state before aggregation is initiated dictate the fibril formation propensity after aggregation. We conclude the driving forces that accelerate aggregation, when heparin is added, do not override the subtle intra- or interprotein interactions induced by the initial solvent conditions. In other words, the balance of protein-protein vs protein-solvent interactions present in the initial solution conditions is a critical driving force for fibril formation.

  8. Tau Aggregation Propensity Engrained in Its Solution State

    PubMed Central

    2016-01-01

    A peptide fragment of the human tau protein which stacks to form neat cross β-sheet fibrils, resembling that found in pathological aggregation, 273GKVQIINKKLDL284 (here “R2/WT”), was modified with a spin-label at the N-terminus. With the resulting peptide, R2/G273C-SL, we probed events at time scales spanning seconds to hours after aggregation is initiated using transmission electron microscopy (TEM), thioflavin T (THT) fluorescence, ion mobility mass spectrometry (IMMS), electron paramagnetic resonance (EPR), and Overhauser dynamic nuclear polarization (ODNP) to determine if deliberate changes to its conformational states and population in solution influence downstream propensity to form fibrillar aggregates. We find varying solution conditions by adding the osmolyte urea or TMAO, or simply using different buffers (acetate buffer, phosphate buffer, or water), produces significant differences in early monomer/dimer populations and conformations. Crucially, these characteristics of the peptide in solution state before aggregation is initiated dictate the fibril formation propensity after aggregation. We conclude the driving forces that accelerate aggregation, when heparin is added, do not override the subtle intra- or interprotein interactions induced by the initial solvent conditions. In other words, the balance of protein–protein vs protein–solvent interactions present in the initial solution conditions is a critical driving force for fibril formation. PMID:26484390

  9. 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.

  10. Recovery of acetic acid from waste streams by extractive distillation.

    PubMed

    Demiral, H; Yildirim, M Ercengiz

    2003-01-01

    Wastes have been considered to be a serious worldwide environmental problem in recent years. Because of increasing pollution, these wastes should be treated. However, industrial wastes can contain a number of valuable organic components. Recovery of these components is important economically. Using conventional distillation techniques, the separation of acetic acid and water is both impractical and uneconomical, because it often requires large number of trays and a high reflux ratio. In practice special techniques are used depending on the concentration of acetic acid. Between 30 and 70% (w/w) acetic acid contents, extractive distillation was suggested. Extractive distillation is a multicomponent-rectification method similar in purpose to azeotropic distillation. In extractive distillation, to a binary mixture which is difficult or impossible to separate by ordinary means, a third component termed an entrainer is added which alters the relative volatility of the original constituents, thus permitting the separation. In our department acetic acid is used as a solvent during the obtaining of cobalt(III) acetate from cobalt(II) acetate by an electrochemical method. After the operation, the remaining waste contains acetic acid. In thiswork, acetic acid which has been found in this waste was recovered by extractive distillation. Adiponitrile and sulfolane were used as high boiling solvents and the effects of solvent feed rate/solution feed rate ratio and type were investigated. According to the experimental results, it was seem that the recovery of acetic acid from waste streams is possible by extractive distillation.

  11. 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.

  12. Buffer gas acquisition and storage

    NASA Astrophysics Data System (ADS)

    Parrish, Clyde F.; Lueck, Dale E.; Jennings, Paul A.

    2001-02-01

    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 CO2 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 (N2), and argon (Ar) through a multiple-membrane system and the individual membranes from room temperature to 193 K and 10 kPa to 300 kPa. Concentrations were measured with a gas chromatograph. The end result was data necessary to design a system that could separate CO2, N2, and Ar. .

  13. Acetate Kinase Isozymes Confer Robustness in Acetate Metabolism

    PubMed Central

    Chan, Siu Hung Joshua; Nørregaard, Lasse; Solem, Christian; Jensen, Peter Ruhdal

    2014-01-01

    Acetate kinase (ACK) (EC no: 2.7.2.1) interconverts acetyl-phosphate and acetate to either catabolize or synthesize acetyl-CoA dependent on the metabolic requirement. Among all ACK entries available in UniProt, we found that around 45% are multiple ACKs in some organisms including more than 300 species but surprisingly, little work has been done to clarify whether this has any significance. In an attempt to gain further insight we have studied the two ACKs (AckA1, AckA2) encoded by two neighboring genes conserved in Lactococcus lactis (L. lactis) by analyzing protein sequences, characterizing transcription structure, determining enzyme characteristics and effect on growth physiology. The results show that the two ACKs are most likely individually transcribed. AckA1 has a much higher turnover number and AckA2 has a much higher affinity for acetate in vitro. Consistently, growth experiments of mutant strains reveal that AckA1 has a higher capacity for acetate production which allows faster growth in an environment with high acetate concentration. Meanwhile, AckA2 is important for fast acetate-dependent growth at low concentration of acetate. The results demonstrate that the two ACKs have complementary physiological roles in L. lactis to maintain a robust acetate metabolism for fast growth at different extracellular acetate concentrations. The existence of ACK isozymes may reflect a common evolutionary strategy in bacteria in an environment with varying concentrations of acetate. PMID:24638105

  14. Thermally programmable pH buffers.

    PubMed

    Van Gough, Dara; Bunker, Bruce C; Roberts, Mark E; Huber, Dale L; Zarick, Holly F; Austin, Mariah J; Wheeler, Jill S; Moore, Diana; Spoerke, Erik D

    2012-11-01

    Many reactions in both chemistry and biology rely on the ability to precisely control and fix the solution concentrations of either protons or hydroxide ions. In this report, we describe the behavior of thermally programmable pH buffer systems based on the copolymerization of varying amounts of acrylic acid (AA) groups into N-isopropylacrylamide polymers. Because the copolymers undergo phase transitions upon heating and cooling, the local environment around the AA groups can be reversibly switched between hydrophobic and hydrophilic states affecting the ionization behavior of the acids. Results show that moderate temperature variations can be used to change the solution pH by two units. However, results also indicate that the nature of the transition and its impact on the pH values are highly dependent on the AA content and the degree of neutralization.

  15. Kallolide A acetate pyrazoline.

    PubMed

    Rodríguez-Escudero, Idaliz; Marrero, Jeffrey; Rodríguez, Abimael D

    2012-01-01

    IN THE CRYSTAL STRUCTURE OF KALLOLIDE A ACETATE PYRAZOLINE [SYSTEMATIC NAME: 7-methyl-16-oxo-4,10-bis-(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza-tetra-cyclo-[9.4.2.1(6,9).0(1,12)]octa-deca-6,8,14-trien-5-yl acetate], C(23)H(28)N(2)O(5), there is a 12-member-ed carbon macrocyclic structure. In addition, there is a tris-ubstituted furan ring, an approximately planar γ-lactone ring [maximum deviation of 0.057 (3) Å] and a pyraz-oline ring, the latter in an envelope conformation. The pyrazoline and the γ-lactone rings are fused in a cis configuration. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions, forming a two-dimensional network parallel to (001). An intra-molecular C-H⋯O hydrogen bond is also present.

  16. Kallolide A acetate pyrazoline

    PubMed Central

    Rodríguez-Escudero, Idaliz; Marrero, Jeffrey; Rodríguez, Abimael D.

    2012-01-01

    In the crystal structure of kallolide A acetate pyrazoline [systematic name: 7-methyl-16-oxo-4,10-bis­(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza­tetra­cyclo­[9.4.2.16,9.01,12]octa­deca-6,8,14-trien-5-yl acetate], C23H28N2O5, there is a 12-member­ed carbon macrocyclic structure. In addition, there is a tris­ubstituted furan ring, an approximately planar γ-lactone ring [maximum deviation of 0.057 (3) Å] and a pyraz­oline ring, the latter in an envelope conformation. The pyrazoline and the γ-lactone rings are fused in a cis configuration. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions, forming a two-dimensional network parallel to (001). An intra­molecular C—H⋯O hydrogen bond is also present. PMID:22259545

  17. Mechanisms underlying the transport and intracellular metabolism of acetic acid in the presence of glucose in the yeast Zygosaccharomyces bailii.

    PubMed

    Sousa, M J; Rodrigues, F; Côrte-Real, M; Leão, C

    1998-03-01

    Zygosaccharomyces bailii ISA 1307 displays biphasic growth in a medium containing a mixture of glucose (0.5%, w/v) and acetic acid (0.5%, w/v), pH 5.0 and 3.0. In cells harvested during the first growth phase, no activity of a mediated acetic acid transport system was found. Incubation of these cells in phosphate buffer with cycloheximide for 1 h restored activity of an acetic acid carrier which behaved as the one present in glucose-grown cells. These results indicated that the acetic acid carrier is probably present in cells from the first growth phase of the mixed medium but its activity was affected by the presence of acetic acid in the culture medium. In glucose-grown cells, after incubation in phosphate buffer with glucose and acetic acid, the activity of the acetic acid carrier decreased significantly with increased acid concentration in the incubation buffer. At acid concentrations above 16.7 mM, no significant carrier activity was detectable. Furthermore, the intracellular acid concentration increased with the extracellular one and was inversely correlated with the activity of the acetic acid carrier, suggesting the involvement of a feedback inhibition mechanism in the regulation of the carrier. During biphasic growth, the first phase corresponded to a simultaneous consumption of glucose and acetic acid, and the second to the utilization of the remaining acid. The enzyme acetyl-CoA synthetase was active in both growth phases, even in the presence of glucose. Activity of isocitrate lyase and phosphoenolpyruvate carboxykinase was found only in acetic-acid-grown cells. Thus it appears that both membrane transport and acetyl-CoA synthetase and their regulation are important for Z. bailii to metabolize acetic acid in the presence of glucose. This fact correlates with the high resistance of this yeast to environments with mixtures of sugars and acetic acid such as those often present during wine fermentation.

  18. 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.

  19. 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.

  20. 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

  1. Good's buffers as a basis for developing self-buffering and biocompatible ionic liquids for biological research.

    PubMed

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

    2014-06-01

    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.

  2. Randomised control trial of pH buffered lignocaine with adrenaline in outpatient operations.

    PubMed

    Masters, J E

    1998-07-01

    Bicarbonate buffering of local anaesthetics is known to significantly decrease the pain of their administration and yet few practising surgeons do so. A double-blind randomised cross-over clinical trial was conducted to confirm the practicality and efficacy of bicarbonate buffering of lignocaine with adrenaline in the setting of a busy local anaesthetic operating theatre. 40 patients received either buffered or control local anaesthetic solutions in equivalent sites on opposite sides of the body. The pain of each injection was rated from 0 (no pain) to 10 (extreme pain). The mean pain score for the buffered solution was significantly lower than the control solution (3.06 vs 4.34, P = 0.002). Bicarbonate buffering of lignocaine with adrenaline is effective, inexpensive and simple; its widespread use should be encouraged.

  3. Enhancement of acid tolerance in Zymomonas mobilis by a proton-buffering peptide.

    PubMed

    Baumler, David J; Hung, Kai F; Bose, Jeffrey L; Vykhodets, Boris M; Cheng, Chorng M; Jeong, Kwang-Cheol; Kaspar, Charles W

    2006-07-01

    A portion of the cbpA gene from Escherichia coli K-12 encoding a 24 amino acid proton-buffering peptide (Pbp) was cloned via the shuttle vector pJB99 into E. coli JM105 and subsequently into Zymomonas mobilis CP4. Expression of Pbp was confirmed in both JM105 and CP4 by HPLC. Z. mobilis CP4 carrying pJB99-2 (Pbp) exhibited increased acid tolerance (p < 0.05) in acidified TSB (HCl [pH 3.0] or acetic acid [pH 3.5]), glycine-HCl buffer (pH 3.0), and sodium acetate-acetic acid buffer (pH 3.5) in comparison to the parent strain (CP4) and CP4 with pJB99 (control plasmid). Although the expression of Pbp influenced survival at a low pH, the minimum growth pH was unaffected. Growth of Z. mobilis in the presence of ampicillin also significantly increased acid tolerance by an unknown mechanism. Results from this study demonstrate that the production of a peptide with a high proportion of basic amino acids can contribute to protection from low pH and weak organic acids such as acetic acid.

  4. Optimizing Giant Unilamellar Vesicle Growth in a Physiological Buffer

    NASA Astrophysics Data System (ADS)

    Lambright, Geoffrey; Huang, Juyang

    2002-10-01

    Liposomes of 40 to 70 microns in diameter are good model systems for microscopy study of biomembrane heterogeneity. They also have a potential to be incorporated into biosensors. We search for the optimum condition to produce large numbers of giant unilamellar vesicles (GUV) in a physiological buffer. A thin lipid film is first dried on a test tube, and then slowly hydrated by water vapor before a buffer solution is added. We found that the yield of GUVs can be significantly influenced by the surface characteristics of the test tubes. By selecting the material of test tubes and optimizing other experimental conditions, we have increased the GUV yield more than ten fold.

  5. 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.

  6. An integrated recirculating optical buffer.

    PubMed

    Park, Hyundai; Mack, John P; Bluementhal, Daniel J; Bowers, John E

    2008-07-21

    This paper reports an integrated optical buffer consisting of a low loss silicon waveguide delay line and a silicon evanescent gate matrix switch. The integrated device demonstrates an error free operation at 40 Gb/s data rate with a packet delay of 1.1 ns. This demonstration also highlights the silicon evanescent device platform to realize new types of photonic integrated devices by combining the low loss silicon passive components with the silicon evanescent photonic active devices.

  7. 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.

  8. Comparative study of the catalytic activity of [Mn(II)(bpy)2Cl2] and [Mn2(III/IV)(mu-O)2(bpy)4](ClO4)3 in the H2O2 induced oxidation of organic dyes in carbonate buffered aqueous solution.

    PubMed

    Rothbart, Sabine; Ember, Erika; van Eldik, Rudi

    2010-04-07

    The kinetics of the hydrogen peroxide induced oxidative degradation of the azo dye Orange II in aqueous carbonate buffered solution were studied for the oxo-bridged [Mn(2)(III/IV)(mu-O)(2)(bpy)(4)](ClO(4))(3) complex and its mononuclear analogue [Mn(II)(bpy)(2)Cl(2)] as catalysts to reveal the underlying reaction mechanism and reactive intermediates participating in the catalytic cycle. Both catalysts show identical oxidative reactivity when used at equimolar manganese concentration. If a simple Mn(II) salt and a 1 : 2 concentration of bipyridine are added to the substrate and oxidant containing reaction mixture, the same oxidative reactivity as found for both readily prepared catalysts was observed for several investigated substrates. This demonstrates the in situ accessibility of a reactive intermediate and its precursor complex. The crucial role of bicarbonate as co-catalyst was studied. The distinct dependence of the observed rate constant for the oxidation reaction on the total carbonate concentration can be accounted for in terms of in situ generation of peroxycarbonate. EPR and rapid scan UV/Vis measurements of the reaction of hydrogen peroxide in carbonate buffered solution with [Mn(2)(III/IV)(mu-O)(2)(bpy)(4)](ClO(4))(3) and [Mn(II)(bpy)(2)Cl(2)], revealed for both catalysts the presence of monomeric Mn(II) and Mn(IV)-oxo species as the main intermediates. The proposed reaction mechanism involves two-electron oxidation of a mononuclear Mn(II) precursor complex to a high-valent Mn(IV)=O intermediate as catalytically active species. Differences in the activity of in situ prepared catalyst precursors of different metal to ligand ratios are reported. The 1 : 2 complex was found to be the catalytically more active precursor for the oxidation of the selected substrates, whereas the 1 : 3 complex rather catalyzed the disproportion of hydrogen peroxide.

  9. Bi-directional ACET micropump for on-chip biological applications.

    PubMed

    Vafaie, Reza Hadjiaghaie; Ghavifekr, Habib Badri; Van Lintel, Harald; Brugger, Juergen; Renaud, Philippe

    2016-03-01

    The ability to control and pump high ionic strength fluids inside microchannels forms a major advantage for clinical diagnostics and drug screening processes, where high conductive biological and physiological buffers are used. Despite the known potential of AC electro-thermal (ACET) effect in different biomedical applications, comparatively little is known about controlling the velocity and direction of fluid inside the chip. Here, we proposed to discretize the conventional electrodes to form various asymmetric electrode structures in order to control the fluid direction by simple switching the appropriate electric potential applied to the discretized electrodes. The ACET pumping effect was numerically studied by solving electrical, thermal and hydrodynamic multi-physic coupled equations to optimize the geometrical dimensions of the discretized system. PBS solutions with different ionic strength were seeded with 1 μm sized fluorescent particles and electrothermally driven fluid motion was observed inside the channel for different electrode structures. Experimental analyses confirm that the proposed micropump is efficient for a conductivity range between 0.1 and 1 S/m and the efficiency improves by increasing the voltage amplitude. Behavior of the proposed electrode-electrolyte system is discussed by lumped circuit model. Frequency response of system illustrated that the optimal frequency range increases by increasing the conductivity of medium. For 0.18 S/m PBS solution, the constant pumping effect was observed at frequency range between 100 kHz and 1 MHz, while frequency range of 100 kHz to 5 MHZ was observed for 0.42 S/m. The characteristics of experimental results were in good agreement with the theoretical model.

  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. Hydrogen production by fermentation using acetic acid and lactic acid.

    PubMed

    Matsumoto, Mitsufumi; Nishimura, Yasuhiko

    2007-03-01

    Microbial hydrogen production from sho-chu post-distillation slurry solution (slurry solution) containing large amounts of organic acids was investigated. The highest hydrogen producer, Clostridium diolis JPCC H-3, was isolated from natural environment and produced hydrogen at 6.03+/-0.15 ml from 5 ml slurry solution in 30 h. Interestingly, the concentration of acetic acid and lactic acid in the slurry solution decreased during hydrogen production. The substrates for hydrogen production by C. diolis JPCC H-3, in particular organic acids, were investigated in an artificial medium. No hydrogen was produced from acetic acid, propionic acid, succinic acid, or citric acid on their own. Hydrogen and butyric acid were produced from a mixture of acetic acid and lactic acid, showing that C. diolis. JPCC H-3 could produce hydrogen from acetic acid and lactic acid. Furthermore, calculation of the Gibbs free energy strongly suggests that this reaction would proceed. In this paper, we describe for the first time microbial hydrogen production from acetic acid and lactic acid by fermentation.

  12. 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

  13. Survival of Salmonella strains differing in their biofilm-formation capability upon exposure to hydrochloric and acetic acid and to high salt.

    PubMed

    Hasegawa, Akio; Hara-Kudo, Yukiko; Kumagai, Susumu

    2011-09-01

    Acidic and osmotic treatments are part of hurdle systems to control pathogens such as Salmonella in food. In the current study, Salmonella enterica isolates previously shown to differ in their ability to form biofilms were grown in diluted tryptic soy broth (TSB) (1:5 dilution in distilled water) and subsequently exposed to phosphate-buffered saline (PBS) adjusted to pH 3.0 with HCl, PBS adjusted to pH 3.9 with acetic acid or rice vinegar diluted 1:15 with distilled water (pH 3.9). Cells grown in diluted TSB were also exposed to distilled water, pH 7.6, containing 5 M NaCl. No differences in survival upon exposure to PBS adjusted to pH 3.0 with HCl or distilled water containing high salt were observed between the isolates; however, exposure to acetic acid and rice vinegar resulted in lower survival levels of isolates previously shown to be poor biofilm formers. The numbers (log(10) cfu/ml) of surviving cells after exposure for 36 hr to acetic acid and rice vinegar were 4.43 ± 0.24 vs. 2.27 ± 0.87 (P<0.05) and 5.19 ± 0.12 vs. 2.33 ± 0.93 (P<0.05) for isolates with a high vs. low biofilm-forming ability. The survival data could be fitted with the Weibull model. The data suggest that the ability of Salmonella strains to survive in the presence of acetic acid and rice vinegar parallels their ability to form biofilms. Thus, Salmonella with a high biofilm-formation capability might be more difficult to kill with acetic acid found in foods or cleaning solutions.

  14. Ion selective permeation through cellulose acetate membranes in forward osmosis.

    PubMed

    Irvine, Gavin J; Rajesh, Sahadevan; Georgiadis, Michael; Phillip, William A

    2013-12-03

    Solute-solute interactions can have a dramatic impact on the permeation of solutes through dense polymeric membranes. In particular, understanding how solute-solute interactions can affect the design of osmotically driven membrane processes (ODMPs) is critical to the successful development of these emerging water treatment and energy generation processes. In this work, we investigate the influence that solute-solute interactions have on nitrate permeation through an asymmetric cellulose acetate forward osmosis membrane. A series of experiments that included systematic modifications to the cation paired with nitrate, the identity of the draw solute, and the solution pH were conducted. These experiments reveal that in the unique operating geometry of ODMPs, where solute containing solutions are present on both sides of the membrane, nitrate fluxes are significantly higher (>15 times in some cases) than predicted by existing models for solute permeation in ODMPs. The identity of the cation paired with nitrate influences the flux of nitrate; the identity of the cation in the draw solution does not affect the flux of nitrate; however, the identity of the anion in the draw solution has the most significant impact on the flux of nitrate. These results suggest that an ion exchange mechanism, which allows nitrate to switch rapidly with anions from the draw solution, is present when cellulose acetate based membranes are used in ODMPs.

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

    PubMed

    Trewby, William; Livesey, Duncan; Voïtchovsky, Kislon

    2016-03-07

    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.

  16. Buffer Zone Requirements for Soil Fumigant Applications

    EPA Pesticide Factsheets

    Updated pesticide product labels require fumigant users to establish a buffer zone around treated fields to reduce risks to bystanders. Useful information includes tarp testing guidance and a buffer zone calculator.

  17. Urban Runoff: Model Ordinances for Aquatic Buffers

    EPA Pesticide Factsheets

    Aquatic Buffers serve as natural boundaries between local waterways and existing development. The model and example ordinaces below provide suggested language or technical guidance designed to create the most effective stream buffer zones possible.

  18. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes voyage, steering gear other than hydraulic must be designed with suitable buffering arrangements to relieve...

  19. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes voyage, steering gear other than hydraulic must be designed with suitable buffering arrangements to relieve...

  20. Intrinsic cytosolic calcium buffering properties of single rat cardiac myocytes.

    PubMed Central

    Berlin, J R; Bassani, J W; Bers, D M

    1994-01-01

    Intracellular passive Ca2+, buffering was measured in voltage-clamped rat ventricular myocytes. Cells were loaded with indo-1 (K+ salt) to an estimated cytosolic concentration of 44 +/- 5 microM (Mean +/- SEM, n = 5), and accessible cell volume was estimated to be 24.5 +/- 3.6 pl. Ca2+ transport by the sarcoplasmic reticulum (SR) Ca-ATPase and sarcolemmal Na-Ca exchange was inhibited by treatment with thapsigargin and Na-free solutions, respectively. Extracellular [Ca2+] was maintained at 10 mM and, in some experiments, the mitochondrial uncoupler "1799" was used to assess the degree of mitochondrial Ca2+ uptake. To perform single cell titrations, intracellular Ca2+ ([Ca2+]i) was increased progressively by a train of depolarizing voltage clamp pulses from -40 to +10 mV. The total Ca2+ gain with each pulse was calculated by integration of the Ca current and then analyzed as a function of the rapid change in [Ca2+]i during the pulse. In the range of [Ca2+]i from 0.1 to 2 microM, overall cell buffering was well described as a single lumped Michaelis-Menten type species with an apparent dissociation constant, KD, of of 0.63 +/- 0.07 microM (n = 5) and a binding capacity, Bmax, of 162 +/- 15 mumol/l cell H2O. Correction for buffering attributable to cytosolic indo-1 gives intrinsic cytosolic Ca2+ buffering parameters of KD = 0.96 +/- 0.18 microM and Bmax = 123 +/- 18 mumol/l cell H2O. The fast Ca2+ buffering measured in this manner agrees reasonably with the characteristics of known rapid Ca buffers (e.g., troponin C, calmodulin, and SR Ca-ATPase), but is only about half of the total Ca2+ buffering measured at equilibrium. Inclusion of slow Ca buffers such as the Ca/Mg sites on troponin C and myosin can account for the differences between fast Ca2+ buffering in phase with the Ca current measured in the present experiments and equilibrium Ca2+ buffering. The present data indicate that a rapid rise of [Ca2+]i from 0.1 to 1 microM during a contraction requires

  1. The Solubility Rules: Why Are All Acetates Soluble?

    NASA Astrophysics Data System (ADS)

    van der Sluys, William G.

    2001-01-01

    According to the solubility rules presented in many introductory chemistry texts, all (or most) acetate salts are soluble in aqueous solution. The thermodynamic factors that contribute to the solubility of acetates are compared with those of other slightly basic anions. In particular, the hydration enthalpy of acetate is calculated using the Born-Haber approach, from lattice energies, heats of solution, and the hydration energies of several cations. The hydration enthalpy of acetate (-375 kJ/mol) is similar to that of chloride ({355 kJ/mol), nitrite ({383 kJ/mol), and nitrate ({370 kJ/mol), which are all considerably less exothermic than fluoride ({497 kJ/mol). This was somewhat unexpected, since hydration enthalpies generally correlate well with the acid-base properties of an ion, and acetate is more basic than fluoride. Factors influencing the solubility and acid-base properties of acetates, such as the electron donating and hydrophobic nature of the methyl group, are discussed in light of the thermodynamic data.

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

    PubMed

    Sundaramurthi, Prakash; Suryanarayanan, Raj

    2011-06-02

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

  3. Effects of hypertonic buffer composition on lymph node uptake and bioavailability of rituximab, after subcutaneous administration.

    PubMed

    Fathallah, Anas M; Turner, Michael R; Mager, Donald E; Balu-Iyer, Sathy V

    2015-03-01

    The subcutaneous administration of biologics is highly desirable; however, incomplete bioavailability after s.c. administration remains a major challenge. In this work we investigated the effects of excipient dependent hyperosmolarity on lymphatic uptake and plasma exposure of rituximab as a model protein. Using Swiss Webster (SW) mice as the animal model, we compared the effects of NaCl, mannitol and O-phospho-L-serine (OPLS) on the plasma concentration of rituximab over 5 days after s.c. administration. An increase was observed in plasma concentrations in animals administered rituximab in hypertonic buffer solutions, compared with 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 the improved lymphatic trafficking as evident from the increase in the fraction of dose trafficked through the lymph nodes in the presence of hypertonic buffers. The fraction of the dose trafficked through the lymphatics, as estimated by the model, increased from 0.05% in isotonic buffer to 13% in hypertonic buffer containing NaCl to about 30% for hypertonic buffers containing high dose OPLS and mannitol. The data suggest that hypertonic solutions may be a viable option for improving s.c. bioavailability.

  4. 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

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

    PubMed

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

    2012-01-03

    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.

  6. Nitrification utilizing CaCO3 as the buffering agent.

    PubMed

    Green, M; Ruskol, Y; Tarre, S; Loewenthal, R E

    2002-03-01

    Nitrification utilizing chalk (calcium carbonate) as the buffering agent was investigated. Three different fluidized bed reactor configurations were examined in order to study the effect of reactor layout on nitrification and concomitant chalk dissolution. The first system consisted of two interconnected columns with high recycle rate, one containing zeolite as the carrier for the nitrifying biomass and the other chalk as the buffering agent. The second reactor system consisted of a single column containing both zeolite and chalk particles. In the third system, nitrification was carried out in a single column where chalk particles were used both as the carrier for the biomass and as the buffer. Results showed that only the reactor with chalk acting as both the buffering agent and the biomass carrier could be operated without external buffer (NaHCO3) addition. This system operated at high ammonium removal rates of up to 2.5 g N l(-1) reactor d(-1) even though the bulk solution of the reactor had a low pH of 5.5. The high nitrification efficiency at this low pH was probably mainly a result of a favorable microenvironment surrounding the nitrifying biomass attached to the chalk.

  7. 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.

  8. 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...

  9. Anodic stripping voltammetry at in situ bismuth-plated carbon and gold microdisc electrodes in variable electrolyte content unstirred solutions.

    PubMed

    Baldrianova, L; Svancara, I; Economou, A; Sotiropoulos, S

    2006-10-27

    Carbon and gold microdisc electrodes (30 and 10 microm, respectively) have been tested as substrates for in situ bismuth film plating from unstirred solutions of variable acetate buffer content and were subsequently used in the anodic stripping voltammetry determination of Pb(II) and Cd(II) ions. The effects of Bi(III) concentration, analyte accumulation time, stirring as well as supporting electrolyte content have been studied. Under optimal conditions good voltammetric responses were obtained by means of square wave anodic stripping voltammetry in unstirred analyte solutions of 5 x 10(-8) to 10(-6)M, even in the absence of added buffer. In an indicative application, Pb(II) ion levels were determined in tap water using bismuth-plated carbon microdisc electrodes.

  10. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  11. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  12. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets...

  13. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets the specifications of the...

  14. Vitamin-loaded electrospun cellulose acetate nanofiber mats as transdermal and dermal therapeutic agents of vitamin A acid and vitamin E.

    PubMed

    Taepaiboon, Pattama; Rungsardthong, Uracha; Supaphol, Pitt

    2007-09-01

    The present contribution reports the use of mats of electrospun cellulose acetate (CA; acetyl content=39.8%; Mw=30,000 Da) nanofibers as carriers for delivery of the model vitamins, all-trans retinoic acid or vitamin A acid (Retin-A) and alpha-tocopherol or vitamin E (Vit-E). The amounts of Vit-E and Retin-A loaded in the base CA solution [17% w/v in 2:1 v/v acetone/N,N-dimethylacetamide (DMAc)] were 5 and 0.5 wt% (based on the weight of CA), respectively. Cross-sectionally round and smooth fibers were obtained. The average diameters of these fibers ranged between 247 and 265 nm. The total immersion of the vitamin-loaded as-spun CA fiber mats in the acetate buffer solutions containing either 0.5 vol % Tween 80 or 0.5 vol % Tween 80 and 10 vol % methanol was used to arrive at the cumulative release of the vitamins from the fiber mat samples. The same was also conducted on the vitamin-loaded solution-cast CA films for comparison. In most cases, the vitamin-loaded as-spun fiber mats exhibited a gradual and monotonous increase in the cumulative release of the vitamins over the test periods (i.e., 24 h for Vit-E-loaded samples and 6 h for Retin-A-loaded ones), while the corresponding as-cast films exhibited a burst release of the vitamins.

  15. Pallidol hexa­acetate ethyl acetate monosolvate

    PubMed Central

    Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.

    2013-01-01

    The entire mol­ecule of pallidol hexa­acetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis­[4-(acet­yloxy)phen­yl]-4b,5,9b,10-tetra­hydro­indeno­[2,1-a]indene-1,3,6,8-tetrayl tetra­acetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate mol­ecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ▶). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexa­acetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100 Å) is 54.73 (6)°, indicating a significant fold in the mol­ecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70 (5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carb­oxy)—C—C torsion angles = −70.24 (14), −114.43 (10) and −72.54 (13)°]. In the crystal, a three-dimensional architecture is sustained by C—H⋯O inter­actions which encompass channels in which the disordered ethyl acetate mol­ecules reside. PMID:24046702

  16. Analytical model for radionuclide transport in the buffer zone of the deep geological disposal

    NASA Astrophysics Data System (ADS)

    Tsao, L. D.; Chen, J. S.; Li, M. H.

    2015-12-01

    Radioactive nuclear waste poses long-term threat to human beings and the environment because that remains radioactive after millions of years. Therefore, radioactive wastes must be isolated from the living environment for millennia. A deep geological disposal entails a combination of four parts: vitrified waste form, imaginary zone, buffer zone and excavation-affected zone. The buffer zone constituted by bentonite clay provides a high level of containment of the radioactivity in the wastes over a very long time period. Analytical solution is an efficient tool for the performance evaluation of the buffer zone. This study develops a new analytical model to diffusion equation in cylindrical coordinate for describing radionuclide transport in the buffer zone. The derived solution is compared against the previous solution to illustrate the validity of previous solution which was derived using a diffusion equation in Cartesian coordinates.

  17. A quantitative comparison of spectroscopic and energy data, in solution, of NHO and OHO hydrogen bonds and gas-phase proton affinities: complexes of pyridines and pyridine N-oxides with acetic acids

    NASA Astrophysics Data System (ADS)

    Dega-Szafran, Zofia; Hrynio, Andrzej; Szafran, Miroslaw

    1990-11-01

    The correlations between the centre of gravity (ν H) of the broad IR vibrations, chemical shifts (δ H) of hydrogen-bonded protons and enthalpies of hydroben bonds (-Δ H) of two series of complexes (pyridines and pyridine N-oxides) with trifluoroacetic, dichloroacetic, chloroacetic and acetic acids, and the difference between the gas-phase proton affinity of bases ( PA(B)) and that of conjugate bases ( PA(A -)) were investigated. Complexes of pyridines with all these acids can be treated as one category and complexes of pyridine N-oxides as another. On the other hand, correlations of ν H and δ H with aqueous p Ka values consist of separate lines for each acid. The PA(A -) and PA(B) values provide an excellent basicity scale for hydrogen bonds in solvents of low and medium polarity.

  18. Simultaneous determination of 2-naphthoxyacetic acid and indole-3-acetic acid by first derivation synchronous fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Xiangxiang; Wan, Yiqun

    2013-07-01

    A simple, rapid, sensitive and selective method for simultaneously determining 2-naphthoxyacetic acid (BNOA) and Indole-3-Acetic Acid (IAA) in mixtures has been developed using derivation synchronous fluorescence spectroscopy based on their synchronous fluorescence. The synchronous fluorescence spectra were obtained with Δλ = 100 nm in a pH 8.5 NaH2PO4-NaOH buffer solution, and the detected wavelengths of quantitative analysis were set at 239 nm for BNOA and 293 nm for IAA respectively. The over lapped fluorescence spectra were well separated by the synchronous derivative method. Under optimized conditions, the limits of detection (LOD) were 0.003 μg/mL for BNOA and 0.012 μg/mL for IAA. This method is simple and expeditious, and it has been successfully applied to the determination of 2-naphthoxyacetic acid and indole-3-acetic acid in fruit juice samples with satisfactory results. The samples were only filtrated through a 0.45 μm membrane filter, which was free from the tedious separation procedures. The obtaining recoveries were in the range of 83.88-87.43% for BNOA and 80.76-86.68% for IAA, and the relative standard deviations were all less than 5.0%. Statistical comparison of the results with high performance liquid chromatography Mass Spectrometry (HPLC-MS) method revealed good agreement and proved that there were no significant difference in the accuracy and precision between these two methods.

  19. Simultaneous determination of 2-naphthoxyacetic acid and indole-3-acetic acid by first derivation synchronous fluorescence spectroscopy.

    PubMed

    Liu, Xiangxiang; Wan, Yiqun

    2013-07-01

    A simple, rapid, sensitive and selective method for simultaneously determining 2-naphthoxyacetic acid (BNOA) and Indole-3-Acetic Acid (IAA) in mixtures has been developed using derivation synchronous fluorescence spectroscopy based on their synchronous fluorescence. The synchronous fluorescence spectra were obtained with Δλ=100 nm in a pH 8.5 NaH2PO4-NaOH buffer solution, and the detected wavelengths of quantitative analysis were set at 239 nm for BNOA and 293 nm for IAA respectively. The over lapped fluorescence spectra were well separated by the synchronous derivative method. Under optimized conditions, the limits of detection (LOD) were 0.003 μg/mL for BNOA and 0.012 μg/mL for IAA. This method is simple and expeditious, and it has been successfully applied to the determination of 2-naphthoxyacetic acid and indole-3-acetic acid in fruit juice samples with satisfactory results. The samples were only filtrated through a 0.45 μm membrane filter, which was free from the tedious separation procedures. The obtaining recoveries were in the range of 83.88-87.43% for BNOA and 80.76-86.68% for IAA, and the relative standard deviations were all less than 5.0%. Statistical comparison of the results with high performance liquid chromatography Mass Spectrometry (HPLC-MS) method revealed good agreement and proved that there were no significant difference in the accuracy and precision between these two methods.

  20. Kinetics of Imidazole Catalyzed Ester Hydrolysis: Use of Buffer Dilutions to Determine Spontaneous Rate, Catalyzed Rate, and Reaction Order.

    ERIC Educational Resources Information Center

    Lombardo, Anthony

    1982-01-01

    Described is an advanced undergraduate kinetics experiment using buffer dilutions to determine spontaneous rate, catalyzed rate, and reaction order. The reaction utilized is hydrolysis of p-nitro-phenyl acetate in presence of imidazole, which has been shown to enhance rate of the reaction. (Author/JN)

  1. 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.

  2. Stability of buffer-free freeze-dried formulations: A feasibility study of a monoclonal antibody at high protein concentrations.

    PubMed

    Garidel, Patrick; Pevestorf, Benjamin; Bahrenburg, Sven

    2015-11-01

    We studied the stability of freeze-dried therapeutic protein formulations over a range of initial concentrations (from 40 to 160 mg/mL) and employed a variety of formulation strategies (including buffer-free freeze dried formulations, or BF-FDF). Highly concentrated, buffer-free liquid formulations of therapeutic monoclonal antibodies (mAbs) have been shown to be a viable alternative to conventionally buffered preparations. We considered whether it is feasible to use the buffer-free strategy in freeze-dried formulations, as an answer to some of the known drawbacks of conventional buffers. We therefore conducted an accelerated stability study (24 weeks at 40 °C) to assess the feasibility of stabilizing freeze-dried formulations without "classical" buffer components. Factors monitored included pH stability, protein integrity, and protein aggregation. Because the protein solutions are inherently self-buffering, and the system's buffer capacity scales with protein concentration, we included highly concentrated buffer-free freeze-dried formulations in the study. The tested formulations ranged from "fully formulated" (containing both conventional buffer and disaccharide stabilizers) to "buffer-free" (including formulations with only disaccharide lyoprotectant stabilizers) to "excipient-free" (with neither added buffers nor stabilizers). We evaluated the impacts of varying concentrations, buffering schemes, pHs, and lyoprotectant additives. At the end of 24 weeks, no change in pH was observed in any of the buffer-free formulations. Unbuffered formulations were found to have shorter reconstitution times and lower opalescence than buffered formulations. Protein stability was assessed by visual inspection, sub-visible particle analysis, protein monomer content, charge variants analysis, and hydrophobic interaction chromatography. All of these measures found the stability of buffer-free formulations that included a disaccharide stabilizer comparable to buffer

  3. 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.

  4. Retention of ionisable compounds on high-performance liquid chromatography XIX. pH variation in mobile phases containing formic acid, piperazine and tris as buffering systems and methanol as organic modifier.

    PubMed

    Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

    2009-07-10

    In previous works a model to estimate the pH of methanol-aqueous buffer mobile phases from the aqueous pH and concentration of the buffer and the fraction of organic modifier was developed. This model was successfully applied and validated for buffers prepared from ammonia, acetic, phosphoric and citric acids. In the present communication this model has been extended to formic acid, piperazine and tris(hydroxymethyl)aminomethane buffers. Prior to the modelling work, the pK(a) values of the studied buffers at several methanol-water compositions were determined.

  5. Biophysical stability of hyFc fusion protein with regards to buffers and various excipients.

    PubMed

    Lim, Jun Yeul; Kim, Nam Ah; Lim, Dae Gon; Eun, Chang-yong; Choi, Donghoon; Jeong, Seong Hoon

    2016-05-01

    A novel non-cytolytic hybrid Fc (hyFc) with an intact Ig structure without any mutation in the hyFc region, was developed to construct a long-acting agonistic protein. The stability of interleukin-7 (IL-7) fused with the hyFc (GXN-04) was evaluated to develop early formulations. Various biophysical methods were utilized and three different buffer systems with various pH ranges were investigated including histidine-acetate, sodium citrate, and tris buffers. Various excipients were incorporated into the systems to obtain optimum protein stability. Two evident thermal transitions were observed with the unfolding of IL-7 and hyFc. The Tm and ΔH increased with pH, suggesting increased conformational stability. Increased Z-average size with PDI and decreased zeta potential with pH increase, with the exception of tris buffer, showed aggregation issues. Moreover, tris buffer at higher pH showed aggregation peaks from DLS. Non-ionic surfactants were effective against agitation by outcompeting protein molecules for hydrophobic surfaces. Sucrose and sorbitol accelerated protein aggregation during agitation, but exhibited a protective effect against oxidation, with preferential exclusion favoring the compact states of GXN-04. The stability of GXN-04 was varied by basal buffers and excipients, hence the buffers and excipients need to be evaluated carefully to achieve the maximum stability of proteins.

  6. 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

  7. Selective frame dropping based on hypothetical reference decoder buffer model for initial buffering delay reduction

    NASA Astrophysics Data System (ADS)

    Deshpande, Sachin

    2008-02-01

    We propose a method for selective frame dropping based on hypothetical reference decoder buffer model for initial buffering delay reduction. The client side buffering consists of two logical buffers: a de-jitter buffer and a pre-decoder buffer. To playback an encoded bit-stream without underflow the client must do a minimum initial buffering. This minimum initial buffering is a property of the bit-stream. The minimum initial buffering relates to the pre-decoder buffer. In addition the client can do additional initial buffering to handle network jitter and other bandwidth variations. Our proposed approach relates to reducing the minimum initial buffering delay for an already encoded bit-stream. We propose a method for selectively dropping frames to reduce the amount of initial buffering the client needs to do to avoid underflow during the streaming. Our proposed method is especially applicable to pre-stored content. The method is also particularly useful for variable bit-rate (VBR) encoded media. The method can be used by a streaming server. Alternatively the method can be implemented by a trans-rater/ transcoder. In a preferred embodiment our method can be applied in advance on a pre-stored bit-stream to decide which frames to drop to reduce the required minimum initial buffering.

  8. 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.

  9. High effective cytosolic H+ buffering in mouse cortical astrocytes attributable to fast bicarbonate transport.

    PubMed

    Theparambil, Shefeeq M; Deitmer, Joachim W

    2015-09-01

    Cytosolic H(+) buffering plays a major role for shaping intracellular H(+) shifts and hence for the availability of H(+) for biochemical reactions and acid/base-coupled transport processes. H(+) buffering is one of the prime means to protect the cell from large acid/base shifts. We have used the H(+) indicator dye BCECF and confocal microscopy to monitor the cytosolic H(+) concentration, [H(+)]i, in cultured cortical astrocytes of wild-type mice and of mice deficient in sodium/bicarbonate cotransporter NBCe1 (NBCe1-KO) or in carbonic anhydrase isoform II (CAII-KO). The steady-state buffer strength was calculated from the amplitude of [H(+)]i transients as evoked by CO2/HCO3(-) and by butyric acid in the presence and absence of CO2/HCO3(-). We tested the hypotheses if, in addition to instantaneous physicochemical H(+) buffering, rapid acid/base transport across the cell membrane contributes to the total, "effective" cytosolic H(+) buffering. In the presence of 5% CO2/26 mM HCO3(-), H(+) buffer strength in astrocytes was increased 4-6 fold, as compared with that in non-bicarbonate, HEPES-buffered solution, which was largely attributable to fast HCO3 (-) transport into the cells via NBCe1, supported by CAII activity. Our results show that within the time frame of determining physiological H(+) buffering in cells, fast transport and equilibration of CO2/H(+)/HCO3(-) can make a major contribution to the total "effective" H(+) buffer strength. Thus, "effective" cellular H(+) buffering is, to a large extent, attributable to membrane transport of base equivalents rather than a purely passive physicochemical process, and can be much larger than reported so far. Not only physicochemical H(+) buffering, but also rapid import of HCO3(-) via the electrogenic sodium-bicarbonate cotransporter NBCe1, supported by carbonic anhydrase II (CA II), was identified to enhance cytosolic H(+) buffer strength substantially.

  10. Simultaneous acetic acid separation and monosaccharide concentration by reverse osmosis.

    PubMed

    Zhou, Fanglei; Wang, Cunwen; Wei, Jiang

    2013-03-01

    This study aimed to investigate the feasibility and efficiency of simultaneous acetic acid separation and sugar concentration in model lignocellulosic hydrolyzates by reverse osmosis. The effects of operation parameters such as pH, temperature, pressure and feed concentration on the solute retentions were examined with a synthetic xylose–glucose–acetic acid model solution. Results showed that the monosaccharides were almost completely rejected at above 20 bar, while the acetic acid retention increased with the increase in pH and pressure, and decreased with the temperature increase. The maximum separation factors of acetic acid over xylose and glucose reached as high as 211.5 and 228.4 at pH 2.93 (the initial pH of model lignocellulosic hydrolyzates), 40 °C and 20 bar. Furthermore, the concentration and diafiltration process were employed at optimal operation conditions. Consequently, a high sugar concentration and a beneficially lower acetic acid concentration were simultaneously achieved by reverse osmosis.

  11. 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.

  12. Development and validation of a reversed-phase liquid chromatographic method for analysis of estradiol valerate and medroxyprogesterone acetate in a tablet formulation.

    PubMed

    Segall, A; Hormaechea, F; Vitale, M; Perez, V; Pizzorno, M T

    1999-04-01

    A simple and accurate liquid chromatographic method was developed for estimation of estradiol valerate and medroxyprogesterone acetate in pharmaceuticals. Drugs were chromatographed on a reverse phase C18 column, using a mixture (30:70) of ammonium nitrate buffer and acetonitrile and eluants monitored at a wavelength of 280 nm. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for its linearity, accuracy, precision and selectivity. Due to its simplicity and accuracy, the authors believe that the method may be used for routine quality control analysis. It does not require any specific sample preparation except the use of a column guard before the analytical column and suitable prefilter attached to the syringe prior to injection.

  13. 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.

  14. Density measurements of potassium phosphate buffer from 4 to 45 degrees C.

    PubMed

    Schiel, John E; Hage, David S

    2005-01-30

    Potassium phosphate buffer is often used in methods such as equilibrium dialysis, high performance liquid chromatography (HPLC), and affinity capillary electrophoresis (ACE) for characterizing the binding of drugs and hormones with proteins or other ligands within the body. In these experiments, the buffer density is often approximated to be that of water and the concentrations of all reagents are assumed to be constant with temperature. However, some difference in density between phosphate buffer and water would be expected, and variations in this density could lead to significant changes in the concentrations of dissolved solutes with temperature. This, in turn, could affect the binding observed for a solute-ligand system in such a buffer. In this study, the densities of potassium phosphate buffers with concentrations up to 0.10M were measured at or near physiological pH for temperatures ranging from 4-45 degrees C. The general change in density versus temperature followed a quadratic equation, while the changes in density with concentration and pH followed a linear response. The results were used to formulate a general equation that could be used to calculate the density of potassium phosphate buffer at any pH, temperature, and concentration within the tested range. This equation and more specialized relationships developed in the temperature, concentration, and pH studies were found to give much greater accuracy in describing the density of these buffers versus a previous relationship developed for solutions containing only potassium dihydrogen phosphate.

  15. Microbiological preservation of cucumbers for bulk storage by the use of acetic acid and food preservatives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microbial growth did not occur when cucumbers were preserved without a thermal process by storage in solutions containing acetic acid, sodium benzoate, and calcium chloride to maintain tissue firmness. The concentrations of acetic acid and sodium benzoate required to assure preservation were low en...

  16. 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.

  17. Electrolyte effects on hydrogen evolution and solution resistance in microbial electrolysis cells

    NASA Astrophysics Data System (ADS)

    Merrill, Matthew D.; Logan, Bruce E.

    Protonated weak acids commonly used in microbial electrolysis cell (MEC) solutions can affect the hydrogen evolution reaction (HER) through weak acid catalysis, and by lowering solution resistance between the anode and the cathode. Weak acid catalysis of the HER with protonated phosphate, acetate, and carbonate electrolyte species improved MEC performance by lowering the cathode's overpotential by up to 0.30 V at pH 5, compared to sodium chloride electrolytes. Deprotonation of weak acids into charged species at higher pHs improved MEC performance primarily by increasing the electrolyte's conductivity and therefore decreasing the solution resistance between electrodes. The potential contributions from weak acid catalysis and solution resistance were compared to determine whether a reactor would operate more efficiently at lower pH because of the HER, or at higher pH because of solution resistance. Phosphate and acetate electrolytes allowed the MEC to operate more efficiently under more acidic conditions (pH 5). Carbonate electrolytes increased performance from pH 5 to 9 due to a relatively large increases in conductivity. These results demonstrate that specific buffers can substantially contribute to MEC performance through both reduction in cathode overpotential and solution resistance.

  18. 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.

  19. Spatial buffering of potassium ions in brain extracellular space.

    PubMed Central

    Chen, K C; Nicholson, C

    2000-01-01

    It has long been assumed that one important mechanism for the dissipation of local potassium gradients in the brain extracellular space is the so-called spatial buffer, generally associated with glial cells. To date, however, there has been no analytical description of the characteristic patterns of K(+) clearance mediated by such a mechanism. This study reanalyzed a mathematical model of Gardner-Medwin (1983, J. Physiol. (Lond.). 335:393-426) that had previously been solved numerically. Under suitable approximations, the transient solutions for the potassium concentrations and the corresponding membrane potentials of glial cells in a finite, parallel domain were derived. The analytic results were substantiated by numerical simulations of a detailed two-compartment model. This simulation explored the dependence of spatial buffer current and extracellular K(+) on the distribution of inward rectifier K(+) channels in the glial endfoot and nonendfoot membranes, the glial geometric length, and the effect of passive KCl uptake. Regarding the glial cells as an equivalent leaky cable, the analyses indicated that a maximum endfoot current occurs when the glial geometric length is equal to the corresponding electrotonic space constant. Consequently, a long glial process is unsuitable for spatial buffering, unless the axial space constant can match the length of the process. Finally, this study discussed whether the spatial buffer mechanism is able to efficiently transport K(+) over distances of more than several glial space constants. PMID:10827962

  20. Sodium acetate as a replacement for sodium bicarbonate in medical toxicology: a review.

    PubMed

    Neavyn, Mark J; Boyer, Edward W; Bird, Steven B; Babu, Kavita M

    2013-09-01

    Sodium bicarbonate is central to the treatment of many poisonings. When it was placed on the FDA drug shortage list in 2012, alternative treatment strategies to specific poisonings were considered. Many hospital pharmacies, poison centers, and medical toxicologists proposed sodium acetate as an adequate alternative, despite a paucity of data to support its use in medical toxicology. The intention of this review is to educate the clinician on the use of sodium acetate and to advise them on the potential adverse events when given in excess. We conducted a literature search focused on the pharmacology of sodium acetate, its use as a buffer in pathologic acidemia and dialysis baths, and potential adverse events associated with excess sodium acetate infusion. It appears safe to replace sodium bicarbonate infusion with sodium acetate on an equimolar basis. The metabolism of acetate, however, is more complex than bicarbonate. Future prospective studies will be needed to confirm the efficacy of sodium acetate in the treatment of the poisoned patient.

  1. NMR spectroscopy reveals that RNase A is chiefly denatured in 40% acetic acid: implications for oligomer formation by 3D domain swapping.

    PubMed

    López-Alonso, Jorge Pedro; Bruix, Marta; Font, Josep; Ribó, Marc; Vilanova, Maria; Jiménez, María Angeles; Santoro, Jorge; González, Carlos; Laurents, Douglas V

    2010-02-10

    Protein self-recognition is essential in many biochemical processes and its study is of fundamental interest to understand the molecular mechanism of amyloid formation. Ribonuclease A (RNase A) is a monomeric protein that may form several oligomers by 3D domain swapping of its N-terminal alpha-helix, C-terminal beta-strand, or both. RNase A oligomerization is induced by 40% acetic acid, which has been assumed to mildly unfold the protein by detaching the terminal segments and consequently facilitating intersubunit swapping, once the acetic acid is removed by lyophilization and the protein is redissolved in a benign buffer. Using UV difference, near UV circular dichroism, folding kinetics, and multidimensional heteronuclear NMR spectroscopy, the conformation of RNase A in 40% acetic acid and in 8 M urea has been characterized. These studies demonstrate that RNase A is chiefly unfolded in 40% acetic acid; it partially retains the native helices, whereas the beta-sheet is fully denatured and all X-Pro peptide bonds are predominantly in the trans conformation. Refolding occurs via an intermediate, I(N), with non-native X-Pro peptide bonds. I(N) is known to be populated during RNase A refolding following denaturation in concentrated solutions of urea or guanidinium chloride, and we find that urea- or GdmCl-denatured RNase A can oligomerize during refolding. By revealing the importance of a chiefly denaturated state and a refolding intermediate with non-native X-Pro peptide bonds, these findings revise the model for RNase A oligomerization via 3D domain swapping and have general implications for amyloid formation.

  2. A Simple Way to Pattern Mn_12-acetate Thin Films

    NASA Astrophysics Data System (ADS)

    Kim, K.; Seo, D. M.; Means, J.; Viswanathan, M.; Teizer, W.

    2004-03-01

    We have observed that Mn_12-acetate ([Mn_12O_12(CH_3COO)_16(H_2O)_4]ot2CH_3COOHot4H_2O) molecules, dissolved in organic solvents, can be self-assembled along the edge of the Mn_12 solution droplet on a Si/SiO2 substrate as the solvent is evaporated. This phenomenon may be related to the well known "coffee-stain effect"”, which leads to a dense particulate deposit along the edge of a drying droplet of coffee on a solid surface. In our study, we have observed such a deposit of Mn_12-acetate at the perimeter of a droplet, after a dilute solution in various organic solvents has been dried. We investigated how the deposits depend on the evaporation rate. Also, we controlled the concentration of the solution to find its relation to the resulting pattern deposit. By patterning the surface with resist and performing a lift-off we created what are, to our knowledge, the first artificial patterns of Mn_12-acetate. This may allow for convenient thin film devices of Mn_12-acetate and work in this direction is ongoing. This work was supported by the Texas Higher Education Coordinating Board and Texas A University.

  3. 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.

  4. TREATMENT OF AMMONIUM NITRATE SOLUTIONS

    DOEpatents

    Boyer, T.W.; MacHutchin, J.G.; Yaffe, L.

    1958-06-10

    The treatment of waste solutions obtained in the processing of neutron- irradiated uranium containing fission products and ammonium nitrate is described. The object of this process is to provide a method whereby the ammonium nitrate is destroyed and removed from the solution so as to permit subsequent concentration of the solution.. In accordance with the process the residual nitrate solutions are treated with an excess of alkyl acid anhydride, such as acetic anhydride. Preferably, the residual nitrate solution is added to an excess of the acetic anhydride at such a rate that external heat is not required. The result of this operation is that the ammonium nitrate and acetic anhydride react to form N/sub 2/ O and acetic acid.

  5. Inhibition of ice growth and recrystallization by zirconium acetate and zirconium acetate hydroxide.

    PubMed

    Mizrahy, Ortal; Bar-Dolev, Maya; Guy, Shlomit; Braslavsky, Ido

    2013-01-01

    The control over ice crystal growth, melting, and shaping is important in a variety of fields, including cell and food preservation and ice templating for the production of composite materials. Control over ice growth remains a challenge in industry, and the demand for new cryoprotectants is high. Naturally occurring cryoprotectants, such as antifreeze proteins (AFPs), present one solution for modulating ice crystal growth; however, the production of AFPs is expensive and inefficient. These obstacles can be overcome by identifying synthetic substitutes with similar AFP properties. Zirconium acetate (ZRA) was recently found to induce the formation of hexagonal cavities in materials prepared by ice templating. Here, we continue this line of study and examine the effects of ZRA and a related compound, zirconium acetate hydroxide (ZRAH), on ice growth, shaping, and recrystallization. We found that the growth rate of ice crystals was significantly reduced in the presence of ZRA and ZRAH, and that solutions containing these compounds display a small degree of thermal hysteresis, depending on the solution pH. The compounds were found to inhibit recrystallization in a manner similar to that observed in the presence of AFPs. The favorable properties of ZRA and ZRAH suggest tremendous potential utility in industrial applications.

  6. Acetate fuels the cancer engine.

    PubMed

    Lyssiotis, Costas A; Cantley, Lewis C

    2014-12-18

    Cancer cells have distinctive nutrient demands to fuel growth and proliferation, including the disproportionate use of glucose, glutamine, and fatty acids. Comerford et al. and Mashimo et al. now demonstrate that several types of cancer are avid consumers of acetate, which facilitates macromolecular biosynthesis and histone modification.

  7. 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.

  8. 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.

  9. 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...

  10. 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…

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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... 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...

  16. 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... 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...

  17. 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...

  18. Effect of acetic acid in recycling water on ethanol production for cassava in an integrated ethanol-methane fermentation process.

    PubMed

    Yang, Xinchao; Wang, Ke; Zhang, Jianhua; Tang, Lei; Mao, Zhonggui

    2016-11-01

    Recently, the integrated ethanol-methane fermentation process has been studied to prevent wastewater pollution. However, when the anaerobic digestion reaction runs poorly, acetic acid will accumulate in the recycling water. In this paper, we studied the effect of low concentration of acetic acid (≤25 mM) on ethanol fermentation at different initial pH values (4.2, 5.2 or 6.2). At an initial pH of 4.2, ethanol yields increased by 3.0% and glycerol yields decreased by 33.6% as the acetic acid concentration was increased from 0 to 25 mM. Raising the concentration of acetic acid to 25 mM increased the buffering capacity of the medium without obvious effects on biomass production in the cassava medium. Acetic acid was metabolized by Saccharomyces cerevisiae for the reason that the final concentration of acetic acid was 38.17% lower than initial concentration at pH 5.2 when 25 mM acetic acid was added. These results confirmed that a low concentration of acetic acid in the process stimulated ethanol fermentation. Thus, reducing the acetic acid concentration to a controlled low level is more advantageous than completely removing it.

  19. Optimization of protein buffer cocktails using Thermofluor.

    PubMed

    Reinhard, Linda; Mayerhofer, Hubert; Geerlof, Arie; Mueller-Dieckmann, Jochen; Weiss, Manfred S

    2013-02-01

    The stability and homogeneity of a protein sample is strongly influenced by the composition of the buffer that the protein is in. A quick and easy approach to identify a buffer composition which increases the stability and possibly the conformational homogeneity of a protein sample is the fluorescence-based thermal-shift assay (Thermofluor). Here, a novel 96-condition screen for Thermofluor experiments is presented which consists of buffer and additive parts. The buffer screen comprises 23 different buffers and the additive screen includes small-molecule additives such as salts and nucleotide analogues. The utilization of small-molecule components which increase the thermal stability of a protein sample frequently results in a protein preparation of higher quality and quantity and ultimately also increases the chances of the protein crystallizing.

  20. [Mechanical buffering characteristics of feline paw pads].

    PubMed

    Zhang, Xiaopeng; Yang, Jialing; Yu, Hui

    2012-12-01

    In the long time of natural evolution, the bodies of some animals, such as feline, that live in the wild and complicate surroundings have evolved to possess outstanding buffering characteristics, which make the animals adapt to the environment perfectly. These animals generally have well-developed paw pads under their soles to play an important role in attenuating the intensity of impact when they land on the ground. Investigating the buffering characteristics of these animals' paw pads could help us to design "bionic" buffering and energy-absorption devices. In this paper, based on observations of animal jumping test, a simple mass-spring-buffer model was proposed to explore the buffering characteristics of the animals' paw pads. By analytically solving the differential equations of this model, the parameters concerned with paw pads functions were discussed and some significant results were obtained.

  1. Human skin buffering capacity against a reference base sodium hydroxide: in vitro model.

    PubMed

    Ayer, Jean; Maibach, Howard I

    2008-01-01

    This study assesses the possibility of using an in vitro model as an introduction to clinical human models for evaluating the buffering capacity of skin when an irritant is topically applied. Sodium hydroxide (NaOH) was utilized as a model base with a view to elucidate information on preventing and/or treating base-induced damage and better understand buffering mechanisms. NaOH was evaluated in 3 concentrations (0.1N, 0.05N, and 0.025N) to determine if the skin's ability to buffer these solutions was dependent on the concentration of the topically applied solution. De-ionized water (negative control) and unexposed skin (blank control) were also utilized. The model permitted quantitative estimates of buffering capacity and its rapid diminution.

  2. Pain reduction in local anesthetic administration through pH buffering.

    PubMed

    Christoph, R A; Buchanan, L; Begalla, K; Schwartz, S

    1988-02-01

    The effects of pH buffering on the pain of administration and efficacy of three local anesthetics (1% lidocaine, 1% lidocaine with 1:100,000 epinephrine, and 1% mepivacaine) were investigated in a randomized, prospective, double-blind study of 25 adult volunteers. Plain and buffered solutions of the three local anesthetics were prepared, and a 0.5 intradermal injection of each was administered. Pain of anesthetic infiltration was rated from zero to ten. The area of anesthetized skin surrounding each injection site was measured at time intervals following each injection. Buffering the local anesthetics significantly reduced the mean quantitative pain estimates compared to the nonbuffered controls: 1) 1% lidocaine compared with buffered 1% lidocaine, 4.9 +/- 0.4 versus 1.1 +/- 0.2 (P less than 10(-6)); 2) 1% lidocaine with epinephrine compared with buffered 1% lidocaine with epinephrine, 5.1 +/- 0.4 versus 1.8 +/- 0.4 (P less than 10(-6)); and 3) 1% mepivacaine compared with buffered 1% mepivacaine, 5.1 +/- 0.4 versus 0.9 +/- 0.2 (P less than 10(-6)). Onset, extent, and duration of skin anesthesia were not statistically altered by pH buffering. The pain of local anesthetic administration can be dramatically reduced by buffering the local anesthetic prior to its infiltration. Anesthetic efficacy is not compromised, and patient acceptance may be significantly increased.

  3. Investigation of solid-phase buffers for sulfur-oxidizing autotrophic denitrification.

    PubMed

    Sengupta, Sukalyan; Ergas, Sarina J; Lopez-Luna, Erika

    2007-12-01

    This paper investigates biological denitrification using autotrophic microorganisms that use elemental sulfur as an electron donor. In this process, for each gram of nitrate-nitrogen removed, approximately 4.5 g of alkalinity (as calcium carbonate) are consumed. Because denitrification is severely inhibited below pH 5.5, and alkalinity present in the influent wastewaters is less than the alkalinity consumed, an external buffer was needed to arrest any drop in pH from alkalinity consumption. A packed-bed bioreactor configuration is ideally suited to handle variations in flow and nitrate loading from decentralized wastewater treatment systems, as it is a passive system and thus requires minimal maintenance; therefore, a solid-phase buffer packed with the elemental sulfur in the bioreactor is most suitable. In this research, marble chips, limestone, and crushed oyster shells were tested as solid-phase buffers. Bench- and field-scale studies indicated that crushed oyster shell was the most suitable buffer based on (1) the rate of dissolution of buffer and the buffering agent released (carbonate, bicarbonate, or hydroxide), (2) the ability of the buffer surface to act as host for microbial attachment, (3) turbidity of the solution upon release of the buffering agent, and (4) economics.

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

    PubMed Central

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

    1991-01-01

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

  5. Determination of gallium at trace levels using a spectrofluorimetric method in synthetic U-Ga and Ga-As solutions

    NASA Astrophysics Data System (ADS)

    Kara, Derya; Fisher, Andrew; Foulkes, Mike; Hill, Steve J.

    2010-01-01

    A simple, easy to use and selective spectrofluorimetric method for the determination of trace levels of gallium has been developed. A new Schiff base, N-o-vanillidine-2-amino-p-cresol (OVAC) was synthesized and its fluorescence activity with gallium investigated. Based on this chelation reaction, a spectrofluorimetric method has been developed for the determination of gallium in synthetically prepared Ga-U and Ga-As samples buffered at pH 4.0 using acetic acid-sodium acetate. The chelation reaction between Ga(III) and N-o-vanillidine-2-amino-p-cresol was very fast, requiring only 30 min at room temperature to complex completely. The limit of detection (LOD) (3 σ) for Ga(III) was 7.17 nM (0.50 μg L -1), determined from the analysis of 11 different solutions of 20 μg L -1 Ga(III).

  6. Origins of blood acetate in the rat.

    PubMed Central

    Buckley, B M; Williamson, D H

    1977-01-01

    A novel enzymimc cycling assay for the determination of acetate in biological material is described. Measurements of the acetate concentration in blood and liver samples from rats of various ages and nutritional states with this assay are reported. The contribution of the intestine, the liver and the rest of the body to maintaining the concentration of acetate in the circulation is examined. Evidence is presented that the gut flora constitute the main source of acetate in blood of fed adult rats, though endogenous production of acetate is of significance in other situations. The streptozotocin-diabetic rat has an elevated blood acetate concentration. PMID:597244

  7. Buffer salt effects in off-line coupling of capillary electrophoresis and mass spectrometry.

    PubMed

    Marák, Jozef; Stanová, Andrea

    2014-05-01

    In this work, the impact of buffer salts/matrix effects on the signal in direct injection MS with an electrospray interface (DI-ESI-MS) following pITP fractionation of the sample was studied. A range of buffers frequently used in CE analyses (pH 3-10) was prepared containing 10, 50, and 90% v/v of ACN, respectively. The sets of calibration solutions of cetirizine (an antihistaminic drug with an amphiprotic character) within a 0.05-2.0 mg/L concentration range were prepared in different buffers. The greatest enhancements in the MS signal (in terms of change in the slope of the calibration line) were obtained for the beta-alanine buffer (pH 3.5) in positive ionization and for the borate buffer (pH 9.2) in negative ionization, respectively. The procedure was successfully applied to the analysis of buserelin (a peptidic drug). The slope of the calibration line for solutions containing the beta-alanine buffer with 50% of ACN was 4 times higher than for water or urine, respectively. This study clearly demonstrates that the buffer salt/matrix effects in an offline combination of pITP and DI-ESI-MS can also play a positive role, as they can enhance the signal in MS. A similar influence of the above effects can also be presumed in the CE techniques combined on-line with ESI-MS.

  8. Migration behaviour of discontinuous buffers in capillary electrophoresis during protein enrichment.

    PubMed

    Li, Ting; Booker, Christina J; Yeung, Ken K-C

    2012-10-21

    Capillary electrophoresis (CE) is not only an effective separation technique, but can also serve as a sample preparation tool for enrichment and purification at sub-microliter sample volumes. Our approach is based on the use of a discontinuous buffer system consisting of an acid and a base (acetate and ammonium). Proteins and/or peptides with isoelectric points between the pH values of these two buffers will become stacked at the neutralization reaction boundary (NRB). To understand the mechanism of the NRB formation and the electrophoretic migration of various ions during the enrichment, we performed experiments using myoglobin and mesityl oxide to reveal the ion migration patterns at the buffer junction, and utilized Simul 5 to computer simulate the process. The simulated results closely resembled the experimental data, and together, they effectively revealed the characteristics of the discontinuous buffers. Importantly, the discovery allowed the manipulation of NRB behaviours by controlling the discontinuous buffer composition. To illustrate this, the removal of urea as an unwanted background molecule from the enriched protein sample was achieved based on the acquired information.

  9. Comparison of different extraction solutions for the analysis of allergens in hen's egg.

    PubMed

    Hildebrandt, S; Steinhart, H; Paschke, A

    2008-06-01

    An important requirement for the correct procedure of allergen analysis in hen's egg is to obtain complete and unaltered protein extracts. Besides the aim of a quantitative extraction of the allergens from the matrix, it is equally important not to alter their allergenic potential during the extraction process. This paper describes and compares six extraction solutions for the analysis of whole-egg proteins and allergens. These requirements were examined via protein determination according to Bradford [Bradford, M. M. (1976). Rapid and sensitive method for quantitation of microgram quantities of protein utilizing principle of protein-dye binding. Analytical Biochemistry, 72, 248-254] and Kjeldahl [Meyer, A. H. (2006). Lebensmittelrecht, Verlag C.H. Beck München, Stand: 1. February 2006, § 64, Lebensmittel- und Futtermittelgesetzbuch, Amtliche Sammlung von Untersuchungsmethoden, Nr. L 06.00-7] as well as the EAST-inhibition method. It could be demonstrated that the extraction with a urea solution (8M) led to significant interferences during the protein determination, and substantially reduced the allergenic potential of egg proteins. With all other extraction solutions adequate protein contents could be extracted. The highest protein content was achieved by the extraction with phosphate buffered saline followed by a Tween 20 solution, physiological saline, water, and acetate buffer. The results show that none of these extracts - except for the urea solution (8M) - was altered in its' allergenic potential.

  10. Synthesis and regeneration of lead (IV) acetate

    SciTech Connect

    Boyle, T.J.; Al-Shareef, H.N.; Moore, G.J.

    1996-11-01

    Lead acetate [Pb(O{sub 2}CMe){sub 4}] was easily synthesized from a warm solution of Pb{sub 3}O{sub 4}, HO{sub 2}CMe and O(OCMe){sub 2} following literature preparations when the appropriate measures to minimize water contamination were followed. Furthermore, Pb(O{sub 2}CMe){sub 4} which has been decomposed (evidenced by the appearance of a purple color due to oxidation) can be regenerated using a similar preparatory route. Introduction of Pb(O{sub 2}CMe){sub 4} from the two routes outlined above into the IMO process for production of PZT thin films gave films with comparable ferroelectric properties to commercially available Pb(O{sub 2}CMe){sub 4} precursors. However, the freshly synthesized material yields PZT films with better properties compared to the recycled material.

  11. 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.

  12. Social buffering: relief from stress and anxiety.

    PubMed

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

    2006-12-29

    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.

  13. Carbon-isotopic analysis of dissolved acetate

    NASA Technical Reports Server (NTRS)

    Gelwicks, J. T.; Hayes, J. M.

    1990-01-01

    Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

  14. Carbon-isotopic analysis of dissolved acetate.

    PubMed

    Gelwicks, J T; Hayes, J M

    1990-01-01

    Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

  15. The effect of pH and buffer concentration on anode biofilms of Thermincola ferriacetica.

    PubMed

    Lusk, Bradley G; Parameswaran, Prathap; Popat, Sudeep C; Rittmann, Bruce E; Torres, Cesar I

    2016-12-01

    We assessed the effects of pH and buffer concentration on current production and growth of biofilms of Thermincola ferriacetica - a thermophilic, Gram-positive, anode-respiring bacterium (ARB) - grown on anodes poised at a potential of -0.06V vs. SHE in microbial electrolysis cells (MECs) at 60°C. T. ferriacetica generated current in the pH range of 5.2 to 8.3 with acetate as the electron donor and 50mM bicarbonate buffer. Maximum current density was reduced by ~80% at pH5.2 and ~14% at 7.0 compared to pH8.3. Increasing bicarbonate buffer concentrations from 10mM to 100mM resulted in an increase in the current density by 40±6%, from 6.8±1.1 to 11.2±2.7Am(-2), supporting that more buffer alleviated pH depression within T. ferriacetica biofilms. Confocal laser scanning microscopy (CLSM) images indicated that higher bicarbonate buffer concentrations resulted in larger live biofilm thicknesses: from 68±20μm at 10mM bicarbonate to >150μm at 100mM, supporting that buffer availability was a strong influence on biofilm thickness. In comparison to mesophilic Geobacter sulfurreducens biofilms, the faster transport rates at higher temperature and the ability to grow at relatively lower pH allowed T. ferriacetica to produce higher current densities with lower buffer concentrations.

  16. 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.

  17. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and....1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant and animal tissues....

  18. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  19. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  20. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  1. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  2. 21 CFR 582.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium acetate. 582.1721 Section 582.1721 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1721 Sodium acetate. (a) Product. Sodium acetate. (b) Conditions of use. This substance is...

  3. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  4. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  5. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It...

  6. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  7. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  8. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  9. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  10. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... days. (A) 140 milligrams (mg) trenbolone acetate (one implant consisting of 7 pellets, each pellet containing 20 mg trenbolone acetate) per implant dose. (B) 140 mg trenbolone acetate (one implant consisting... 29 mg tylosin tartrate) per implant dose. (ii) Indications for use. For improved feed...

  11. Photochemistry of 2-nitrobenzylidene acetals.

    PubMed

    Sebej, Peter; Solomek, Tomás; Hroudná, L'ubica; Brancová, Pavla; Klán, Petr

    2009-11-20

    Photolysis of dihydroxy compounds (diols) protected as 2-nitrobenzylidene acetals (ONBA) and subsequent acid- or base-catalyzed hydrolysis of the 2-nitrosobenzoic acid ester intermediates result in an efficient and high-yielding release of the substrates. We investigated the scope and limitations of ONBA photochemistry and expanded upon earlier described two-step procedures to show that the protected diols of many structural varieties can also be liberated in a one-pot procedure. In view of the fact that the acetals of nonsymmetrically substituted diols are converted into one of the corresponding 2-nitrosobenzoic acid ester isomers with moderate to high regioselectivity, the mechanism of their formation was studied using various experimental techniques. The experimental data were found to be in agreement with DFT-based quantum chemical calculations that showed the preferential cleavage occurs on the acetal C-O bond in the vicinity of more electron-withdrawing (or less electron-donating) groups. The study also revealed considerable complexity in the cleavage mechanism and that the structural variations in the substrate can significantly alter the reaction pathway. This deprotection strategy was found to be also applicable for 2-thioethanol when released from the corresponding monothioacetal in the presence of a reducing agent, such as ascorbic acid.

  12. Predicting the crystallization propensity of carboxylic acid buffers in frozen systems--relevance to freeze-drying.

    PubMed

    Sundaramurthi, Prakash; Suryanarayanan, Raj

    2011-04-01

    Selective crystallization of buffer components in frozen solutions is known to cause pronounced pH shifts. Our objective was to study the crystallization behavior and the consequent pH shift in frozen aqueous carboxylic acid buffers. Aqueous carboxylic acid buffers were cooled to -25°C and the pH of the solution was measured as a function of temperature. The thermal behavior of solutions during freezing and thawing was investigated by differential scanning calorimetry. The crystallized phases in frozen solution were identified by X-ray diffractometry. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartarate systems, at initial pH buffer component (neutral form) crystallized on cooling, causing an increase in the freeze-concentrate pH. Carboxylic acid buffers were rank ordered based on their propensity to crystallize in frozen solutions. From the aqueous solubility values of these carboxylic acids, which have been reported over a range of temperatures, it was also possible to estimate the degree of supersaturation at the subambient temperature of interest. This enabled us to predict their crystallization propensity in frozen systems. The experimental and the predicted rank orderings were in excellent agreement.

  13. Effects of buffer concentration on voltage-gated H+ currents: does diffusion limit the conductance?

    PubMed Central

    DeCoursey, T E; Cherny, V V

    1996-01-01

    The single-channel proton conductance of the voltage-gated H(+)-selective channel, like that of the F0 component of the H(+)-ATPase, is nearly constant over a wide range of pH encompassing the physiological range. To examine the possible contributions of buffer diffusion and buffer-channel proton transfer reactions to this phenomenon, the effects of buffer concentration on voltage-activated H+ currents were explored in voltage-clamped rat alveolar epithelial cells. Changes in the external buffer concentration ([B]o), evaluated using the whole-cell configuration, had only small effects on H+ currents (IH). Lowering [B]o from 100 to 1 mM did not alter the voltage-activation curve or reversal potential (Vrev) but reduced IH, typically by 10-30%. Changes in internal buffer concentration ([B]i), examined in inside-out patches, usually altered IH more distinctly and subtly changed the kinetics. Overall, the effects of changing buffer concentration were small and subtle. The maximum attenuation of the single-channel H+ current at 1 mM buffer was estimated to be approximately 20% at either mouth of the H+ channel. Therefore, the rate-determining step in H+ permeation is neither deprotonation of buffer at the inner mouth of the channel nor protonation of buffer at the external surface. Evidently the rate of H+ permeation through the channel is itself small enough that diffusion of buffer in bulk solution does not directly limit the conductance significantly. PMID:8804602

  14. Effects of phosphate buffer in parenteral drugs on particle formation from glass vials.

    PubMed

    Ogawa, Toru; Miyajima, Makoto; Wakiyama, Naoki; Terada, Katsuhide

    2013-01-01

    The characteristics of inorganic particles generated in glass vials filled with phosphate buffer solutions were investigated. During storage, particles were visually detected in the phosphate buffer solution in particular glass vials which pass compendial tests of containers for injectable drugs. These particles were considered to be different from ordinal glass delamination, which has been reported in a number of papers because the particles were mainly composed of Al, P and O, but not Si. The formation of the particles accelerated at higher storage temperatures. Among the surface treatments tested for the glass vials, sulfur treatment showed a protective effect on the particle formation in the vials, whereas the SiO(2) coating did not have any protective effects. It was found that the elution ratio of Al and Si in the solution stored in the glass vials after the heating was similar to the ratio of Al and Si in borosilicate glass. However, the Al concentration decreased during storage (5°C, 6 months), and consequently, particle formation was observed in the solution. Adding citrate, which is a chelating agent for Al, effectively suppressed the particle formation in the heated solution. When 50 ppb and higher concentrations of Al ion were added to the phosphate buffer solution, the formation of white particles containing Al, P and O was detected. It is suggested that a phosphate buffer solution in a borosilicate glass vial has the ability to form particles due to interactions with the Al that is eluted from the glass during storage.

  15. Effect of Organic Acid Additions on the General and Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions

    SciTech Connect

    Carranza, R M; Giordano, C M; Rodr?guez, M A; Ilevbare, G O; Rebak, R B

    2007-08-28

    Electrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric. Results show that the corrosion rate of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and picric acids showed a slightly higher corrosion rate, and acetic acid maintained the corrosion rate of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions. Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids.

  16. Sum-frequency generation of acetate adsorption on Au and Pt surfaces: Molecular structure effects

    NASA Astrophysics Data System (ADS)

    Braunschweig, Björn; Mukherjee, Prabuddha; Kutz, Robert B.; Wieckowski, Andrzej; Dlott, Dana D.

    2010-12-01

    The reversible adsorption of acetate on polycrystalline Au and Pt surfaces was investigated with broadband sum-frequency generation (SFG) and cyclic voltammetry. Specifically adsorbed acetate as well as coadsorbed sulfuric acid anions are observed for the first time with SFG and give rise to dramatically different SFG intensities on Au and Pt surfaces. While similar coverages of acetate adlayers on Au and Pt surfaces are well established by previous studies, an identification of the interfacial molecular structure has been elusive. However, we have applied the high sensitivity of SFG for interfacial polar ordering to identify different acetate structures at Au and Pt surfaces in contact with HClO4 and H2SO4 electrolytes. Acetate competes with the formation of surface oxides and shifts the oxidation threshold of both Au and Pt electrodes anodically. Effects of the supporting electrolyte on the formation of acetate adlayers are revealed by comparing SFG spectra in HClO4 and H2SO4 solutions: Sulfuric acid anions modify the potential-dependent acetate adsorption, compete with adsorbed acetate on Au and coadsorb with acetate on Pt surfaces.

  17. Metastable equilibrium solubility behavior of carbonated apatite in the presence of solution strontium.

    PubMed

    Heslop, D D; Bi, Y; Baig, A A; Higuchi, W I

    2004-01-01

    The purpose of this study was to use the concept of metastable equilibrium solubility (MES) to describe the anomalous solubility behavior of carbonated apatite (CAP) in the presence of solution strontium. A CAP sample (4.8 wt% CO(3), synthesized at 70 degrees C) was prepared by precipitation. Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. In order to assess the influence of strontium, MES profiles were then determined in a similar fashion with 20, 30, 40, 50, 60, 70, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. From the compositions of the equilibrating buffer solutions, ion activity products (IAPs) of the form Ca(10-n)Sr(n)(PO(4))(6)(OH)(2) (n = 0-10) were calculated in an attempt to determine the correct function governing the dissolution of the CAP preparation. The results demonstrate the following important findings: (a) at high solution strontium/calcium ratios (i.e., when 60% or more of the solution calcium was replaced by strontium), the MES profiles in all the experiments were found to be essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca(6)Sr(4)(PO(4))(6)(OH)(2), and (b), at low solution strontium/calcium ratios (i.e., when 40% or less of the solution calcium was replaced by strontium), the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.

  18. Calculating Buffer Zones: A Guide for Applicators

    EPA Pesticide Factsheets

    Buffer zones provide distance between the application block (i.e., edge of the treated field) and bystanders, in order to control pesticide exposure risk from soil fumigants. Distance requirements may be reduced by credits such as tarps.

  19. Capture effeciency of a vegetative environmental buffer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Particulate matter emitted from tunnel-ventilated animal feeding operations (AFOs) is known to transport malodorous compounds. As a mitigation strategy, vegetative environmental buffers (VEBs) are often installed surrounding AFOs to capture particulates and induce lofting and dispersion. Currently, ...

  20. Transport and release of transition elements during early diagenesis: Sequential leaching of sediments from MANOP Sites M and H. Part I. pH 5 acetic acid leach

    NASA Astrophysics Data System (ADS)

    Lyle, Mitchell; Heath, G. Ross; Robbins, James M.

    1984-09-01

    Sediments from MANOP sites M and H in the eastern tropical Pacific Ocean can be partitioned into operationally defined phases by means of a sequential leach procedure. This paper reports the results of the first leach in the sequence, an acetic acid solution buffered as p H 5 with sodium acetate. This leach is designed to remove carbonate-bound and sorbed cations. The only cation bound in a consistent ratio to calcium in the carbonate is strontium. The molar ratio is 2 × 10 -3. In contrast, transition metals are sorbed onto the surfaces of other sedimentary particles. The proportions sorbed range from 2 to 10% of the total manganese, about 10% of the total nickel and copper, and less than 1% of the total iron. The pool of sorbed metals in surface sediments is sufficiently large and the rate of biological stirring is sufficiently rapid for this metal reservoir potentially to dominate the porewater reservoir in supplying metals to ferromanganese nodules. A simple model for nodule growth based upon transfer of metals through this reservoir suggests that only 1% of the sedimentary sorbed metals within a radius of 2 to 9 cm is required to support typical nodule growth rates.

  1. Buffer layer for thin film structures

    SciTech Connect

    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.

  2. 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.

  3. A study of different buffers to maximize viability of an oral Shigella vaccine.

    PubMed

    Chandrasekaran, Lakshmi; Lal, Manjari; Van De Verg, Lillian L; Venkatesan, Malabi M

    2015-11-17

    Live, whole cell killed and subunit vaccines are being developed for diarrheal diseases caused by V. cholerae, Shigella species, ETEC, and Campylobacter. Some of these vaccines can be administered orally since this route best mimics natural infection. Live vaccines administered orally have to be protected from the harsh acidic gastric environment. Milk and bicarbonate solutions have been administered to neutralize the stomach acid. For many Shigella vaccine trials, 100-120 ml of a bicarbonate solution is ingested followed by the live vaccine candidate, which is delivered in 30 ml of bicarbonate, water or saline. It is not clear if maximum bacterial viability is achieved under these conditions. Also, volumes of neutralizing buffer that are optimal for adults may be unsuitable for children and infants. To address these questions, we performed studies to determine the viability and stability of a Shigella sonnei vaccine candidate, WRSS1, in a mixture of different volumes of five different buffer solutions added to hydrochloric acid to simulate gastric acidity. Among the buffers tested, bicarbonate solution, rotavirus buffer and CeraVacx were better at neutralizing acid and maintaining the viability of WRSS1. Also, a much smaller volume of the neutralizing buffer was sufficient to counteract stomach acid while maintaining bacterial viability.

  4. 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.

  5. Electrospun cellulose acetate-garnet nanocomposite magnetic fibers for bioseparations.

    PubMed

    Munaweera, Imalka; Aliev, Ali; Balkus, Kenneth J

    2014-01-08

    Cellulose acetate fibers with magnetic properties have recently attracted much attention because of their potential novel applications in biomedicine such as for cell and protein separations, magnetic resonance imaging contrast agents, and magnetic filters. In this work, as synthesized yttrium iron garnet and gadolinium substituted yttrium iron garnet nanoparticles have been used to generate magnetic filter paper. Garnet nanoparticles dispersed in cellulose acetate polymer solutions were electrospun as free-standing nonwoven fiber mats as well as on cellulose filter paper substrates resulting in magnetic filter papers. The magnetic fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and superconducting quantum interference device (SQUID) magnetic property measurements. The resulting magnetic polymer nanocomposites can be easily picked up by an external magnet from a liquid medium. Fluorescein isothiocyanate (FITC) labeled bovine serum albumin (BSA) was separated from solution by using the magnetic filter paper.

  6. 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

  7. Buffer regulation of calcium puff sequences.

    PubMed

    Fraiman, Daniel; Dawson, Silvina Ponce

    2014-02-01

    Puffs are localized Ca(2 +) signals that arise in oocytes in response to inositol 1,4,5-trisphosphate (IP3). They are the result of the liberation of Ca(2 +) from the endoplasmic reticulum through the coordinated opening of IP3 receptor/channels clustered at a functional release site. The presence of buffers that trap Ca(2 +) 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 Ca(2 +) signals and their responses can be modulated. In this paper we extend the stochastic model of a cluster of IP3R-Ca(2 +) 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 Ca(2 +) buffer can increase the average number of channels that participate of a puff.

  8. A miniature biofuel cell operating in a physiological buffer.

    PubMed

    Mano, Nicolas; Mao, Fei; Heller, Adam

    2002-11-06

    A glucose-O2 biofuel cell, consisting only of two electrocatalyst coated 7-mum diameter, 2-cm long carbon fibers is reported. The cell operated continuously at 0.52 V at 37 degrees C in a physiological buffer solution for a week, producing 1.9 muW during the first and 1.0 muW during the last day, generating in the period 0.9 J of electrical energy while passing a charge of 1.7 C. If a similar dimension zinc fiber were utilized in a battery at 100% current efficiency, only 0.016 C would have been generated.

  9. 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.

  10. Advanced treatment of sodium acetate in water by ozone oxidation.

    PubMed

    Yang, De-Min; Yuan, Jian-Mei

    2014-02-01

    Ozone oxidation is an advanced oxidation process for treatment of organic and inorganic wastewater. In this paper, sodium acetate (according to chemical oxygen demand [COD]) was selected as the model pollutant in water, and the degradation efficiencies and mechanism of sodium acetate in water by ozone oxidation were investigated. The results showed that the ozone oxidation was an effective treatment technology for advanced treatment of sodium acetate in water; the COD removal rate obtained the maximum value of 45.89% from sodium acetate solution when the pH value was 10.82, ozone concentration was 100 mg/L, reaction time was 30 minutes, and reaction temperature was 25 degrees C. The COD removal rate increased first and decreased subsequently with the bicarbonate (HCO3-) concentration from 0 to 200 mg/L, the largest decline being 20.35%. The COD removal rate declined by 25.38% with the carbonate (CO3(2-)) concentration from 0 to 200 mg/L; CO3(2-) has a more obvious scavenging effect to inhibit the formation of hydroxyl free radicals than HCO3-. Calcium chloride (CaCl2) and calcium hydroxide (Ca(OH)2) could enhance the COD removal rate greatly; they could reach 77.35 and 96.53%, respectively, after a reaction time of 30 minutes, which was increased by 31.46 and 50.64%, respectively, compared with only ozone oxidation. It was proved that the main ozone oxidation product of sodium acetate was carbon dioxide (CO2), and the degradation of sodium acetate in the ozone oxidation process followed the mechanism of hydroxyl free radicals.

  11. Application of cellulose acetate for controlled release of thymol.

    PubMed

    Milovanovic, Stoja; Markovic, Darka; Aksentijevic, Ksenija; Stojanovic, Dusica B; Ivanovic, Jasna; Zizovic, Irena

    2016-08-20

    Cellulose acetate (CA) was investigated as a carrier towards development of material with controlled release of thymol as a natural substance with strong antibacterial properties using high pressure techniques. Effect of thymol content on CA was confirmed by SEM, FTIR and DSC methods. Kinetic of thymol release from CA was tested using simulated gastric and intestinal fluids (hydrochloric acid and phosphate buffer saline). Results were correlated with Korsmeyer-Peppas and Weibull model. Depending on the thymol content and chemical nature of the release medium, the time of thymol release varied from one to three days indicating CA as a promising carrier of thymol with potential uses from medicine to agriculture. The impregnated CA showed antibacterial activity against 23 tested bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA) which is particularly important bearing in mind that this strain causes fatal infections in humans and animals.

  12. Acetic acid induces pH-independent cellular energy depletion in Salmonella enterica.

    PubMed

    Tan, Sin Mei; Lee, Sui Mae; Dykes, Gary A

    2015-03-01

    Weak organic acids are widely used as preservatives and disinfectants in the food industry. Despite their widespread use, the antimicrobial mode of action of organic acids is still not fully understood. This study investigated the effect of acetic acid on the cell membranes and cellular energy generation of four Salmonella strains. Using a nucleic acid/protein assay, it was established that acetic acid did not cause leakage of intracellular components from the strains. A scanning electron microscopy study further confirmed that membrane disruption was not the antimicrobial mode of action of acetic acid. Some elongated Salmonella cells observed in the micrographs indicated a possibility that acetic acid may inhibit DNA synthesis in the bacterial cells. Using an ATP assay, it was found that at a neutral pH, acetic acid caused cellular energy depletion with an ADP/ATP ratio in the range between 0.48 and 2.63 (p<0.05) that was apparent for the four Salmonella strains. We suggest that this effect was probably due solely to the action of undissociated acid molecules. The antimicrobial effect of acetic acid was better under acidic conditions (ADP/ATP ratio of 5.56 ± 1.27; p<0.05), where the role of both pH and undissociated acid molecules can act together. We concluded that the inhibitory effect of acetic acid is not solely attributable to acidic pH but also to undissociated acid molecules. This finding has implication for the use of acetic acid as an antimicrobial against Salmonella on food products, such as chicken meat, which can buffer its pH.

  13. 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.

  14. Glacial Acetic Acid Adverse Events: Case Reports and Review of the Literature

    PubMed Central

    Doles, William; Wilkerson, Garrett; Morrison, Samantha

    2015-01-01

    Glacial acetic acid is a dangerous chemical that has been associated with several adverse drug events involving patients over recent years. When diluted to the proper concentration, acetic acid solutions have a variety of medicinal uses. Unfortunately, despite warnings, the improper dilution of concentrated glacial acetic acid has resulted in severe burns and other related morbidities. We report on 2 additional case reports of adverse drug events involving glacial acetic acid as well as a review of the literature. A summary of published case reports is provided, including the intended and actual concentration of glacial acetic acid involved, the indication for use, degree of exposure, and resultant outcome. Strategies that have been recommended to improve patient safety are summarized within the context of the key elements of the medication use process. PMID:26448660

  15. Stability of cefozopran hydrochloride in aqueous solutions.

    PubMed

    Zalewski, Przemysław; Skibiński, Robert; Paczkowska, Magdalena; Garbacki, Piotr; Talaczyńska, Alicja; Cielecka-Piontek, Judyta; Jelińska, Anna

    2016-01-01

    The influence of pH on the stability of cefozopran hydrochloride (CZH) was investigated in the pH range of 0.44-13.00. Six degradation products were identified with a hybrid ESI-Q-TOF mass spectrometer. The degradation of CZH as a result of hydrolysis was a pseudo-first-order reaction. As general acid-base hydrolysis of CZH was not occurred in the solutions of hydrochloric acid, sodium hydroxide, acetate, borate and phosphate buffers, kobs = kpH because specific acid-base catalysis was observed. Specific acid-base catalysis of CZH consisted of the following reactions: hydrolysis of CZH catalyzed by hydrogen ions (kH+), hydrolysis of dications (k1H2O), monocations (k2H2O) and zwitter ions (k3H2O) and hydrolysis of zwitter ions (k1OH-) and monoanions (k2OH-) of CZH catalyzed by hydroxide ions. The total rate of the reaction was equal to the sum of partial reactions: [Formula: see text]. CZH similarly like other fourth generation cephalosporin was most stable at slightly acidic and neutral pH and less stable in alkaline pH. The cleavage of the β-lactam ring resulting from a nucleophilic attack on the carbonyl carbon in the β-lactam moiety is the preferred degradation pathway of β-lactam antibiotics in aqueous solutions.

  16. 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.

  17. Characterization of the spherical intermediates and fibril formation of hCT in HEPES solution using solid-state 13C-NMR and transmission electron microscopy.

    PubMed

    Itoh-Watanabe, Hikari; Kamihira-Ishijima, Miya; Kawamura, Izuru; Kondoh, Masashi; Nakakoshi, Masamichi; Sato, Michio; Naito, Akira

    2013-10-21

    Human calcitonin (hCT) is a 32-amino acid peptide hormone that contains an intrachain disulfide bridge between Cys1 and Cys7 and a proline amide at the C-terminus. hCT tends to associate to form a fibril precipitate of the same type as amyloid fibrils, and hence has been studied as a model of amyloid fibril formation. The fibrillation process in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (HEPES) solution was examined using transmission electron microscopy. The rate of hCT fibrillation in HEPES solution was much lower than in phosphate buffer and acetic acid solution. Spherical intermediate aggregates (nuclei) were observed during the early stage of fibril formation. Short proto-fibrils appeared on the surface of the spherical intermediates. Subsequently, the spherical intermediates transformed directly into long proto-fibrils, which then elongated into mature hCT fibrils. The fibrillation process was also examined using solid-state (13)C-NMR spectroscopy, which indicated that the fibril structure was a β-sheet in the central region and a mixture of random coils and β-sheets at the C-terminus. The kinetics of fibril formation was examined in terms of a two-step autocatalytic reaction mechanism. The first-step nucleation rate (k1) was lower in HEPES solution than in phosphate buffer and acetic acid solution because the half-life of the intermediates is significantly longer in HEPES solution. In contrast, the second-step fibril elongation rate (k2) was similar in HEPES solution and acidic solutions. Specific interaction of HEPES molecules with hCT may stabilize the spherical intermediates and consequently inhibit the fibril elongation process of hCT.

  18. Distribution of furfuryl alcohol between water and butyl acetate

    SciTech Connect

    Veber, N.V.; Khisamotdinova, A.I.; Tabachova, S.I.

    1985-06-10

    This paper studies the distribution of furfuryl alcohol between water and butyl acetate, which has a comparatively low solubility in water (0.5 g in 100 ml of water), forming a heterogeneous azeotropic mixture. Butyl acetate is capable of giving a hydrogen bond at the carbonyl oxygen with hydroxyl compounds, which serves as the basis for its use as an extraction reagent. The distribution of furfuryl alcohol between water and butyl acetate was studied without salting out agents, and also in the presence of sodium chloride. The experiments were conducted with model solutions of freshly redistilled furfuryl alcohol by shaking equal volumes of the phases in a separatory funnel at 18-20 C. An analysis of furfuryl alcohol in experiments without salting out was performed by a titrimetric method. The results of the distribution of furfuryl alcohol without salting out agents are presented in a table. The distribution of furfuryl alcohol in butyl acetate in the presence of sodium chloride was studied in a smaller range of concentrations.

  19. Utilization of acetate by Beggiatoa.

    PubMed

    Burton, S D; Morita, R Y; Miller, W

    1966-03-01

    Burton, Sheril D. (Institute of Marine Science, University of Alaska, College), Richard Y. Morita, and Wayne Miller. Utilization of acetate by Beggiatoa. J. Bacteriol. 91:1192-1200. 1966.-A proposed system which would permit acetate incorporation into four-carbon compounds without the presence of key enzymes of the citric acid cycle or glyoxylate cycle is described. In this system, acetyl-coenzyme A (CoA) is condensed with glyoxylate to form malate, which, in turn, is converted to oxaloacetate. Oxaloacetate then reacts with glutamate to produce alpha-ketoglutarate, which is subsequently converted to isocitrate. Cleavage of isocitrate produces glyoxylate and succinate. Thus, the proposed system is similar to the glyoxylate bypass in that malate is produced from glyoxylate and acetyl-CoA, but differs from both the citric acid cycle and the glyoxylate bypass, since citrate and fumarate are not involved. Fumarase, aconitase, catalase, citritase, pyruvate kinase, enolase, phosphoenolpyruvate carboxylase, lactic dehydrogenase, alpha-ketoglutarate dehydrogenase, and condensing enzyme were not detectable in crude extracts of Beggiatoa. Succinate was oxidized by a soluble enzyme not associated with an electron-transport particle. Isocitrate was identified as the sole compound labeled when C(14)O(2) was added to a reduced nicotinamide adenine dinucleotide, CO(2) generating system (crystalline glucose-6-phosphate dehydrogenase and glucose-6-phosphate) in the presence of alpha-ketoglutarate.

  20. 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.

  1. 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…

  2. Vegetative buffer strips for reducing herbicide transport in runoff: effects of season, vegetation, and buffer width

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effectiveness of vegetative buffer strips (VBS) for reducing herbicide transport in runoff may be affected by season, plant species composition, and buffer width. A plot-scale study was conducted from 2007-2012 on an eroded claypan soil with the objectives of: 1) assessing the effects of season ...

  3. Efficacy of Acetic Acid against Listeria monocytogenes Attached to Poultry Skin during Refrigerated Storage.

    PubMed

    Gonzalez-Fandos, Elena; Herrera, Barbara

    2014-09-11

    This work evaluates the effect of acetic acid dipping on the growth of L. monocytogenes on poultry legs stored at 4 °C for eight days. Fresh inoculated chicken legs were dipped into either a 1% or 2% acetic acid solution (v/v) or distilled water (control). Changes in mesophiles, psychrotrophs, Enterobacteriaceae counts and sensorial characteristics (odor, color, texture and overall appearance) were also evaluated. The shelf life of the samples washed with acetic acid was extended by at least two days over the control samples washed with distilled water. L. monocytogenes counts before decontamination were 5.57 log UFC/g, and after treatment with 2% acetic acid (Day 0), L. monocytogenes counts were 4.47 log UFC/g. Legs washed with 2% acetic acid showed a significant (p < 0.05) inhibitory effect on L. monocytogenes compared to control legs, with a decrease of about 1.31 log units after eight days of storage. Sensory quality was not adversely affected by acetic acid. This study demonstrates that while acetic acid did reduce populations of L. monocytogenes on meat, it did not completely inactivate the pathogen. The application of acetic acid may be used as an additional hurdle contributing to extend the shelf life of raw poultry and reducing populations of L. monocytogenes.

  4. Isolation of cellulose from rice straw and its conversion into cellulose acetate catalyzed by phosphotungstic acid.

    PubMed

    Fan, Guozhi; Wang, Min; Liao, Chongjing; Fang, Tao; Li, Jianfen; Zhou, Ronghui

    2013-04-15

    Cellulose was isolated from rice straw by pretreatment with dilute alkaline and acid solutions successively, and it was further transferred into cellulose acetate in the presence of acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The removal of hemicellulose and lignin was affected by the concentration of KOH and the immersion time in acetic acid solution, and 83wt.% content of cellulose in the treated rice straw was obtained after pretreatment with 4% KOH and immersion in acetic acid for 5h. Phosphotungstic acid was found to be an effective catalyst for the acetylation of the cellulose derived from rice straw. The degree of substitution (DS) values revealed a significant effect for the solubility of cellulose acetate, and the acetone-soluble cellulose acetate with DS values around 2.2 can be obtained by changing the amount of phosphotungstic acid and the time of acetylation. Both the structure of cellulose separated from rice straw and cellulose acetate were confirmed by FTIR and XRD.

  5. Enzymatic production of glycerol acetate from glycerol.

    PubMed

    Oh, Seokhyeon; Park, Chulhwan

    2015-02-01

    In this study, we report the enzymatic production of glycerol acetate from glycerol and methyl acetate. Lipases are essential for the catalysis of this reaction. To find the optimum conditions for glycerol acetate production, sequential experiments were designed. Type of lipase, lipase concentration, molar ratio of reactants, reaction temperature and solvents were investigated for the optimum conversion of glycerol to glycerol acetate. As the result of lipase screening, Novozym 435 (Immobilized Candida antarctica lipase B) was turned out to be the optimal lipase for the reaction. Under the optimal conditions (2.5 g/L of Novozym 435, 1:40 molar ratio of glycerol to methyl acetate, 40 °C and tert-butanol as the solvent), glycerol acetate production was achieved in 95.00% conversion.

  6. Labview virtual instruments for calcium buffer calculations.

    PubMed

    Reitz, Frederick B; Pollack, Gerald H

    2003-01-01

    Labview VIs based upon the calculator programs of Fabiato and Fabiato (J. Physiol. Paris 75 (1979) 463) are presented. The VIs comprise the necessary computations for the accurate preparation of multiple-metal buffers, for the back-calculation of buffer composition given known free metal concentrations and stability constants used, for the determination of free concentrations from a given buffer composition, and for the determination of apparent stability constants from absolute constants. As implemented, the VIs can concurrently account for up to three divalent metals, two monovalent metals and four ligands thereof, and the modular design of the VIs facilitates further extension of their capacity. As Labview VIs are inherently graphical, these VIs may serve as useful templates for those wishing to adapt this software to other platforms.

  7. 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.

  8. Determination of tertiary amines and salts of organic acids in acetic acid by catalytic thermometric titration.

    PubMed

    Vajgand, V J; Gaál, F F

    1967-03-01

    A new method of determination of tertiary amines and salts of organic adds in acetic acid solution, to which about 2 % of water and 8% acetic anhydride are added, is described. After the equivalence point, the excess of perchloric acid catalyses the exothermic reaction of water with acetic anhydride. The end-point is determined from the graph of temperature against volume of added titrant. If a slightly soluble compound is produced during the titration, the precision of the new method is superior to that of the potentiometric method.

  9. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  10. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  11. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  12. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  13. Filtrates & Residues: A "Semimicro" Spectrophotometric Determination of the Ksp of Silver Acetate at Various Temperatures.

    ERIC Educational Resources Information Center

    Liebermann, John, Jr.; Yun, Ki J.

    1988-01-01

    Examines a solubility laboratory experiment using silver acetate and spectrophotometers for an Advanced Placement chemistry course. Covers experimental procedure, analysis of saturated solutions, and a discussion of chemistry involved. Includes an absorbance curve for silver ions and solution preparation suggestions. (ML)

  14. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  15. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  16. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  17. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium acetate. 184.1721 Section 184.1721 Food and... Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate (C2H3O2Na, CAS Reg. No. 127-09-3 or C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  18. Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study

    PubMed Central

    Takahashi, Ohgi; Kirikoshi, Ryota; Manabe, Noriyoshi

    2015-01-01

    Succinimide formation from aspartic acid (Asp) residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe) as a model compound, we propose the possibility that acetic acid (AA), which is often used in protein drug formulation for mildly acidic buffer solutions, catalyzes the succinimide formation from Asp residues by acting as a proton-transfer mediator. The proposed mechanism comprises two steps: cyclization (intramolecular addition) to form a gem-diol tetrahedral intermediate and dehydration of the intermediate. Both steps are catalyzed by an AA molecule, and the first step was predicted to be rate-determining. The cyclization results from a bond formation between the amide nitrogen on the C-terminal side and the side-chain carboxyl carbon, which is part of an extensive bond reorganization (formation and breaking of single bonds and the interchange of single and double bonds) occurring concertedly in a cyclic structure formed by the amide NH bond, the AA molecule and the side-chain C=O group and involving a double proton transfer. The second step also involves an AA-mediated bond reorganization. Carboxylic acids other than AA are also expected to catalyze the succinimide formation by a similar mechanism. PMID:25588215

  19. Food waste decomposition in leachbed reactor: role of neutralizing solutions on the leachate quality.

    PubMed

    Selvam, Ammaiyappan; Xu, Su Yun; Gu, Xiang Yang; Wong, Jonathan W C

    2010-03-01

    The neutralization effects of 0.1M NaHCO(3), KPO(4)-buffer (pH 7.0) and sodium acetate (NaOAc) solutions (500 ml/kg food waste/day) on controlling the pH and leachate quality in an acidogenic reactor of food waste anaerobic digestion was investigated. pH of leachate from the reactor was low and ranged from 3.24 to 4.15. Although differences in chemical oxygen demand (COD) were observed, the cumulative COD yields were almost similar. Ammonia concentrations gradually decreased from 26 to 3mg/l after 15 days. Acetic acid was the major fraction and the total VFAs decreased gradually for a week and increased thereafter, with a sharp increase in NaOAc treatment. VFAs yield and acetate/propionate ratio were the highest in NaOAc treatment, followed by NaHCO(3) and KPO(4) treatments. Volatile solids reduction was the lowest in NaOAc treatment (47.5%) and highest in NaHCO(3) treatment (67.0%). With lower decomposition and higher yield of VFA and COD, NaOAc could be used as a neutralizing agent in acidogenic reactors to improve the efficiency of the acidogenesis process.

  20. Aqueous solution dispersement of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  1. Extractive fermentation of acetic acid

    SciTech Connect

    Busche, R.M.

    1991-12-31

    In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium: Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newer Clostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved. Conversely, C. thermoaceticum is a thermophilic anaerobe that operates at high fermentation rates on glucose at neutral pH to produce acetate salts directly in substantially quantitative yields. However, it is severely inhibited by product, which restricts concentration to a dilute 20 g/L. An improved Acetobacter system operating with recycled cells at 50 g/L appears capable of producing acid at $0.38/lb, as compared with a $0.29/lb price for synthetic acid. However, this system has only a limited margin for process improvement. The present Clostridium system cannot compete, since the required selling price would be $0.42/lb. However, if the organism could be adapted to tolerate higher product concentrations at acid pH, selling price could be reduced to $0.22/lb, or about 80% of the price of synthetic acid.

  2. Thermal decarboxylation of acetic acid: Implications for origin of natural gas

    USGS Publications Warehouse

    Kharaka, Y.K.; Carothers, W.W.; Rosenbauer, R.J.

    1983-01-01

    Laboratory experiments on the thermal decarboxylation of solutions of acetic acid at 200??C and 300??C were carried out in hydrothermal equipment allowing for on-line sampling of both the gas and liquid phases for chemical and stable-carbon-isotope analyses. The solutions had ambient pH values between 2.5 and 7.1; pH values and the concentrations of the various acetate species at the conditions of the experiments were computed using a chemical model. Results show that the concentrations of acetic acid, and not total acetate in solution, control the reaction rates which follow a first order equation based on decreasing concentrations of acetic acid with time. The decarboxylation rates at 200??C (1.81 ?? 10-8 per second) and 300??C (8.17 ?? 10-8 per second) and the extrapolated rates at lower temperatures are relatively high. The activation energy of decarboxylation is only 8.1 kcal/mole. These high decarboxylation rates, together with the distribution of short-chained aliphatic acid anions in formation waters, support the hypothesis that acid anions are precursors for an important portion of natural gas. Results of the ??13C values of CO2, CH4, and total acetate show a reasonably constant fractionation factor of about 20 permil between CO2 and CH4 at 300??C. The ??13C values of CO2 and CH4 are initially low and become higher as decarboxylation increases. ?? 1983.

  3. High-performance liquid chromatography-tandem mass spectrometry validation of medroxyprogesterone acetate in products of pork origin and serum.

    PubMed

    Giannetti, Luigi; Barchi, Daniela; Fiorucci, Fulvia; Gennuso, Elisa; Sanna, Patrizia; Pallagrosi, Marco; Neri, Bruno

    2005-08-01

    Different extraction and purification methods are described here to determine medroxyprogesterone acetate (MPA) in pork meat and serum. Spiked samples are investigated over the concentration range of MPA 0.5-20 ng/g. Pork meat tissues are subjected to extraction using organic solvent, and pork serum is simply diluted with acetate buffer. Clean-up is performed using solid-phase extraction on a C18 cartridge, and MPA is eluted with ethanol. Aliquots are injected into a high-performance liquid chromatography-mass spectrometry system. MPA content is determined on the basis of m/z 387-327 and 387-123 transitions.

  4. Asparagine deamidation dependence on buffer type, pH, and temperature.

    PubMed

    Pace, Amanda L; Wong, Rita L; Zhang, Yonghua Taylor; Kao, Yung-Hsiang; Wang, Y John

    2013-06-01

    The deamidation of asparagine into aspartate and isoaspartate moieties is a major pathway for the chemical degradation of monoclonal antibodies (mAbs). It can affect the shelf life of a therapeutic antibody that is not formulated or stored appropriately. A new approach to detect deamidation using ion exchange chromatography was developed that separates papain-digested mAbs into Fc and Fab fragments. From this, deamidation rates of each fragment can be calculated. To generate kinetic parameters useful in setting shelf life, buffers prepared at room temperature and then placed at the appropriate stability temperatures. Solution pH was not adjusted to the same at different temperatures. Deamidation rate at 40°C was faster in acidic buffers than in basic buffers. However, this trend is reversed at 5°C, attributed to the change in hydroxide ion concentration influenced by buffer and temperature. The apparent activation energy was higher for rates generated in an acidic buffer than in a basic buffer. The rate-pH profile for mAb1 can be deconvoluted to Fc and Fab. The Fc deamidation showed a V-shaped profile: deamidation of PENNY peptide is responsible for the rate at high-pH, whereas deamidation of a new site, Asn323, may be responsible for the rate at low-pH. The profile for Fab is a straight line without curvature.

  5. Comparative analyses of universal extraction buffers for assay of stress related biochemical and physiological parameters.

    PubMed

    Han, Chunyu; Chan, Zhulong; Yang, Fan

    2015-01-01

    Comparative efficiency of three extraction solutions, including the universal sodium phosphate buffer (USPB), the Tris-HCl buffer (UTHB), and the specific buffers, were compared for assays of soluble protein, free proline, superoxide radical (O2∙-), hydrogen peroxide (H2O2), and the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and glutathione reductase (GR) in Populus deltoide. Significant differences for protein extraction were detected via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2-DE). Between the two universal extraction buffers, the USPB showed higher efficiency for extraction of soluble protein, CAT, GR, O2∙-, GPX, SOD, and free proline, while the UTHB had higher efficiency for extraction of APX, POD, and H2O2. When compared with the specific buffers, the USPB showed higher extraction efficiency for measurement of soluble protein, CAT, GR, and O2∙-, parallel extraction efficiency for GPX, SOD, free proline, and H2O2, and lower extraction efficiency for APX and POD, whereas the UTHB had higher extraction efficiency for measurement of POD and H2O2. Further comparisons proved that 100 mM USPB buffer showed the highest extraction efficiencies. These results indicated that USPB would be suitable and efficient for extraction of soluble protein, CAT, GR, GPX, SOD, H2O2, O2∙-, and free proline.

  6. Improving phosphate buffer-free cathode performance of microbial fuel cell based on biological nitrification.

    PubMed

    You, Shi-Jie; Ren, Nan-Qi; Zhao, Qing-Liang; Kiely, Patrick D; Wang, Jing-Yuan; Yang, Feng-Lin; Fu, Lei; Peng, Luo

    2009-08-15

    To reduce the amount of phosphate buffer currently used in Microbial Fuel Cell's (MFC's), we investigated the role of biological nitrification at the cathode in the absence of phosphate buffer. The addition of a nitrifying mixed consortia (NMC) to the cathode compartment and increasing ammonium concentration in the catholyte resulted in an increase of cell voltage from 0.3 V to 0.567 V (external resistance of 100 Omega) and a decrease of catholyte pH from 8.8 to 7.05. A large fraction of ammonium was oxidized to nitrite, as indicated by an increase of nitrate-nitrogen (NO(3)(-)-N). An MFC inoculated with an NMC and supplied with 94.2 mgN/l ammonium to the catholyte could generate a maximum power of 2.1+/-0.14 mW (10.94+/-0.73 W/m(3)). This compared favorably to an MFC supplied with either buffered or non-buffered solution. The buffer-free NMC inoculated cathodic chamber showed the smallest polarization resistance, suggesting that nitrification resulted in improved cathode performance. The improved performances of the phosphate buffer-free cathode and cell are positively related to biological nitrification, in which we suggest additional protons produced from ammonium oxidation facilitated electrochemical reduction of oxygen at cathode.

  7. Preirradiation grafting of ethylene vinyl acetate copolymer resins

    NASA Astrophysics Data System (ADS)

    Ringrose, B. J.; Kronfli, E.

    1999-07-01

    Acrylic acid was graft copolymerised on to EVA powdered resins containing 9%, 18% and 28% vinyl acetate. A preirradiation grafting method was used and the effect on graft level of varying the parameters of gamma irradiation dose (2-50 kGy), dose rate (0.5-5 kGy h -1), monomer concentration (2.5-25%) and grafting time (1-4 h) and temperature (35-98°C) was investigated. The graft copolymer resins were converted into film and characterised in terms of their hydrophilicity and electrolytic resistance in alkaline solutions. Depending on the vinyl acetate content and rheological properties of the base EVA copolymer, high graft weight resins can be converted into semipermeable films suitable for a range of applications including battery separator membranes and topical medical dressings.

  8. 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.

  9. 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…

  10. 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)

  11. 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.

  12. Buffer placement improves when topography is considered

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Best Management Practices (BMPs) protect streams by excluding cattle from streambanks and by filtering the run-off flowing from animal heavy use areas like feeding and watering stations. Conservation standards recommend placing buffers and filter strips downslope from heavy use areas, but do not exp...

  13. 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…

  14. Buffering children from marital conflict and dissolution.

    PubMed

    Katz, L F; Gottman, J M

    1997-06-01

    Examined several protective mechanisms that may reduce deleterious correlates of marital conflict and marital dissolution in young children. One set of potential buffers focused on parent-child interaction: parental warmth, parental scaffolding/praise, and inhibition of parental rejection. As a second set of potential buffers, each parent was interviewed about their "meta-emotion philosophy"--that is, their feelings about their own emotions, and their attitudes and responses to their children's anger and sadness. The third set of potential buffers concerned intraindividual characteristics of the child, including the child's intelligence and regulatory physiology (basal vagal tone and vagal suppression). Fifty-six families with a preschool child were studied at two time points: when the children were 5 years old (Time 1) and again when the children were 8 years old (Time 2). At Time 1, naturalistic observations of marital and parent-child interaction were conducted and assessment of child regulatory physiology was obtained through measures of basal vagal tone and suppression of vagal tone. Parents were also interviewed individually about their feelings about their own and their children's emotions, and children's intelligence was assessed. At Time 2, assessment of child outcomes were obtained, including observations of peer interaction, mother ratings of behavior problems and mother and teacher ratings of peer aggression, mother ratings of child physical illness, and measures of achievement. Results indicated that all Time 1 buffering factors protected children in face of marital conflict and dissolution.

  15. Assessment of buffer systems for harvesting proteins from tissue interstitial fluid for proteomic analysis.

    PubMed

    Teng, Pang-ning; Rungruang, Bunja J; Hood, Brian L; Sun, Mai; Flint, Melanie S; Bateman, Nicholas W; Dhir, Rajiv; Bhargava, Rohit; Richard, Scott D; Edwards, Robert P; Conrads, Thomas P

    2010-08-06

    Tissue interstitial fluid (TIF) bathes cells in tissues, and it is hypothesized that TIF proximal to a developing tumor may contain an enriched population of tumor-specific shed and secreted proteins relative to peripheral blood. Extraction of TIF proteins is typically accomplished through passive incubation of surgically resected tissues in phosphate buffered saline (PBS); however, its influence on cellular activity and viability has not been fully explored. The present investigation sought to characterize whether different buffer systems influence the recovered TIF proteome. Five TIF buffer systems were investigated including PBS, Dulbecco's modified Eagle medium (DMEM), and three organ transplantation preservative solutions: Celsior solution S (CS), histidine-tryptophan-ketoglutarate (HTK), and University of Wisconsin (UW). Kidney tumor, adjacent normal kidney, and ovarian tumor tissues were incubated in each of the buffer systems, and the harvested TIF proteins were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Although the present results indicate that no significant differences exist in the recovered proteins from these two neoplasms between the five solution groups, additional sample preparative steps are required prior to LC-MS/MS for TIF proteins harvested from DMEM, UW, CS, and HTK. These data support that PBS is a suitable and convenient solution for harvesting TIF proteins for MS-based proteomics.

  16. 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

  17. Improving performance of inverted organic solar cells using ZTO nanoparticles as cathode buffer layer

    NASA Astrophysics Data System (ADS)

    Tsai, Meng-Yen; Cheng, Wen-Hui; Jeng, Jiann-Shing; Chen, Jen-Sue

    2016-06-01

    In this study, a low-temperature solution-processed zinc tin oxide (ZTO) films are successfully utilized as the cathode buffer layer in the inverted organic P3HT:PCBM bulk heterojunction solar cells. ZTO film cathode buffer layer with an appropriate Sn-doping concentration outperforms the zinc oxide (ZnO) film with an improved power conversion efficiency (1.96% (ZTO film) vs. 1.56% (ZnO film)). Furthermore, ZTO nanoparticles (NPs) are also synthesized via low-temperature solution route and the device with ZTO NPs buffer layer exhibits a significant improvement in device performance to reach a PCE of 2.60%. The crystallinity of the cathode buffer layer plays an influential factor in the performance. From impedance spectroscopy analysis, a correlation between short circuit current (Jsc), carrier life time (τavg) and, thus, PCE is observed. The interplay between composition and crystallinity of the cathode buffer layers is discussed to find their influences on the solar cell performance.

  18. 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.

  19. REMOVAL OF CHLORIDE FROM AQUEOUS SOLUTIONS

    DOEpatents

    Schulz, W.W.

    1959-08-01

    The removal of chlorides from aqueons solutions is described. The process involves contacting the aqueous chloride containing solution with a benzene solution about 0.005 M in phenyl mercuric acetate whereby the chloride anions are taken up by the organic phase and separating the organic phase from the aqueous solutions.

  20. Interaction between sulfonephthalein dyes and chitosan in aqueous solution and its application to the determination of surfactants.

    PubMed

    Yamamoto, Koichi; Adachi, Kana

    2003-08-01

    A spectrophotometric method for the determination of ionic surfactants with Bromophenol Blue (BPB) based on incorporation into a precipitated chitosan was studied. Cationic surfactants (CS+), such as a quaternary ammonium ion containing a long-chain alkyl group, associate with BPB2- buffered at about pH 9 to form the ion associate (CS+)2 x BPB2-. CS+ associates with anionic surfactants (AS-). In the presence of a definite amount of CS+, an increase in the amount of AS- leads to a decrease in the amount of excess CS+, and therefore to a decrease in the amount of the ion associate of CS+ with BPB2-. The addition of a chitosan dissolved in acetic acid to a solution containing these ion associates leads immediately to precipitation of the chitosan and the incorporation of the ion associates (CS+)2 x BPB2- or CS+ x AS- into the precipitated chitosan. After centrifuging, ionic surfactants can be determined by the following two methods: (1) the absorbance of the supernatant solution is measured at 590 nm. (2) After the supernatant solution is separated, the precipitate is dissolved in an acetic acid solution and the absorbance is measured at 625 nm. Because the color of the precipitate is judged by the naked eye, this can be applied to the visual method. This is a simple and rapid method for the determination of a 10(-6) M order of ionic surfactants.

  1. Effects of sodium lactate and acetic acid derivatives on the quality and sensory characteristics of hot-boned pork sausage patties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sodium lactate and acetic acid derivatives were evaluated for their effects on color retention, microbial growth, and sensory attributes of hot-boned pork sausage patties. Treatments included: (a) sodium lactate (L), (b) buffered vinegar (V), (c) sodium lactate and vinegar mixture (LV), (d) control ...

  2. Manufacturing Ethyl Acetate From Fermentation Ethanol

    NASA Technical Reports Server (NTRS)

    Rohatgi, Naresh K.; Ingham, John D.

    1991-01-01

    Conceptual process uses dilute product of fermentation instead of concentrated ethanol. Low-concentration ethanol, extracted by vacuum from fermentation tank, and acetic acid constitutes feedstock for catalytic reaction. Product of reaction goes through steps that increases ethyl acetate content to 93 percent by weight. To conserve energy, heat exchangers recycle waste heat to preheat process streams at various points.

  3. Electron transfer induced fragmentation of acetic acid

    NASA Astrophysics Data System (ADS)

    Ferreira da Silva, F.; Meneses, G.; Almeida, D.; Limão-Vieira, P.

    2014-04-01

    We present negative ion formation driven by electron transfer in atom (K) molecule (acetic acid) collisions. Acetic acid has been found in the interstellar medium, is also considered a biological related compound and as such studying low energy electron interactions will bring new insights as far as induced chemistry is concerned.

  4. CELLULOSE NITRATE-ACETATE MIXED ESTERS

    DTIC Science & Technology

    cellulose acetate . The degree of polymerization of the products, as estimated from viscosity data, shows the occurrence of chain degradation for both...mixed esters showed tensile strength at least comparable to that of films of cellulose nitrate or cellulose acetate . The impact sensitivity of the

  5. Potential Efficiency of Riparian Vegetated Buffer Strips in Intercepting Soluble Compounds in the Presence of Subsurface Preferential Flows

    PubMed Central

    Allaire, Suzanne Edith; Sylvain, Claudia; Lange, Sébastien F.; Thériault, George; Lafrance, Pierre

    2015-01-01

    Buffer strips have been widely recognized as to promote infiltration, deposition and sorption of contaminants for protecting surface water against agricultural contamination. However, such strips do not intercept all contaminants, particularly soluble ones. Although preferential flow (PF) has been suggested as one factor among several decreasing the efficiency of buffer strips, the mechanisms involved are not well understood. This project examines buffer strip efficiency at intercepting solutes when subsurface PF occurs. Two soluble sorbed tracers, FD&C Blue #1 and rhodamine WT, were applied on an agricultural sandy loam soil to evaluate the ability of a naturally vegetated buffer strip to intercept soluble contaminants. Rhodamine was applied about 15 m from the creek, while the Blue was applied 15 m to 165 m from the creek. Tracer concentration was measured over a two-year period in both the creek and the buffer strip through soil and water samples. Although the tracers traveled via different pathways, they both quickly moved toward the creek, passing beneath the buffer strip through the soil matrix. Our results demonstrate that the risk of water contamination by soluble contaminants is high in such systems, even when a well-vegetated buffer strip is used. The design of buffer strips should be modified to account for underground bypass, either by using plants that have deep, fine roots that do not favour PF or by adding a filter extending deep underground that can be regularly changed. PMID:26147093

  6. New approach for the production of cellulose acetate: acetylation of mechanical pulp with subsequent isolation of cellulose acetate by differential solubility

    SciTech Connect

    Barkalow, D.G.

    1987-01-01

    A heretofore uninvestigated approach to the production of cellulose acetate is the acetylation of mechanical pulp with subsequent isolation of the cellulose derivative by differential solubility. The mechanical pulp is produced by refining aspen wood chips in a disc-refiner. Two conventional acetylation techniques, the fibrous and solution process, are employed to acetylate all components of the pulp. The cellulose acetate is isolated from the acetylated lignin and hemicellulose by dissolving in dichloromethane/methanol (9:1, v/v). The advantage of this new approach is that the high costs involved in using an extensively purified dissolving pulp are avoided. Both procedures yield a product that is about 84% cellulose acetate. The remaining acetylated components are lignin and hemicellulose. The average lignin content of the product from the solution process is 3.5% (1.5-4.7% range), and for the fibrous process it is 3.4% (1.2-5% range). The hemicellulose component averages 5.8% (2.5-9.1% range) for the solution process and 6.5% (3.0-8.7% range) for the fibrous process. The yield of cellulose acetate, based on the cellulose content of the original pulp and the product, is 75% for the solution process and 75-80% for the fibrous process. The cellulose acetate degree of polymerization (DP) is dependent on the sulfuric acid catalyst concentration, and on the reaction time in the case of the solution process. The product can be produced with a weight average DP from 1853 to 65 for the solution process, and 980 to 284 for the fibrous process. Applications for the product include lacquers, plastic films, and packaging.

  7. In situ Cr(VI) reduction within coarse-textured, oxide-coated soil and aquifer systems using Fe(II) solutions

    SciTech Connect

    Seaman, J.C.; Bertsch, P.M.; Schwallie, L.

    1999-03-15

    Batch and column techniques were used to evaluate the in situ Cr(VI) reduction and immobilization using Fe(II) solutions within the sediments of the Atlantic Coastal Plain. Remediation treatments included Cr-free groundwater and buffered and unbuffered Fe(II) solutions as either FeCl{sub 2} and FeSO{sub 4}. The slow release of Cr(VI) from the Fe-oxide rich subsurface sediment following exposure to Cr-free solutions indicated that simple pump-and-treat procedures would require extended operation time to meet regulatory standards. In situ reduction was confirmed by the loss of Cr(VI) and Fe(II) from solution and a drop in pH compared to control systems. Batch and column-effluent Cr(VI) decreased with increasing Fe(II), generally failing below detection limits as the persistence of Fe(II) occurred. However, Cr{sub Dissolved}, presumably Cr(III), exceeded regulatory limits due to the low pH ({approx}3.0) induced by oxidation and hydrolysis of Fe(II). Acetate-buffered Fe(II) solutions maintained an elevated pH in the presence of Cr(VI) reduction, making the treatment effective at lowering Cr{sub Dissolved} in batch evaluations. Acetate increased Cr(VI) mobility in columns ahead of the reactive Fe(II) front, suggesting that in situ reduction using soluble chemical additives may be somewhat ineffective due to the enhanced migration of Cr, either Cr(III) or Cr(VI), induced by the treatment solution.

  8. Depomedroxyprogesterone acetate for hot flashes.

    PubMed

    Barton, Debra; Loprinzi, Charles; Quella, Susan; Sloan, Jeff; Pruthi, Sandya; Novotny, Paul

    2002-12-01

    To evaluate the efficacy of a long-acting preparation of medroxyprogesterone acetate for hot flash management, 3 men receiving androgen ablation therapy for prostate cancer and 15 women with a history of breast cancer were treated as part of clinical practice with three biweekly intramuscular injections of 500 mg depomedroxyprogesterone. A review of hot flash diaries and patient charts were completed to evaluate the effectiveness and tolerability of these injections for managing hot flashes. Treatment was associated with an approximate 90% decrease in hot flashes (95% CI 82-97%). Daily hot flash frequency decreased from a mean of 10.9 on the first day of treatment (95% CI 8.0-13.8 hot flashes per day) to a mean of 1.1 hot flashes 6 weeks later (95% CI 0.5-1.8 hot flashes) and to a mean of 0.7 hot flashes 12 weeks following therapy initiation (95% CI 0.1-1.2). Improvement in the hot flashes remained for months after discontinuing the injections in many patients. Reported side effects were minimal. This experience suggests that treatment with depomedroxyprogesterone may be an effective and well-tolerated option for the treatment of hot flashes.

  9. Vesicles protect activated acetic acid.

    PubMed

    Todd, Zoe R; House, Christopher H

    2014-10-01

    Abstract Methyl thioacetate, or activated acetic acid, has been proposed to be central to the origin of life and an important energy currency molecule in early cellular evolution. We have investigated the hydrolysis of methyl thioacetate under various conditions. Its uncatalyzed rate of hydrolysis is about 3 orders of magnitude faster (K=0.00663 s(-1); 100°C, pH 7.5, concentration=0.33 mM) than published rates for its catalyzed production, making it unlikely to accumulate under prebiotic conditions. However, our experiments showed that methyl thioacetate was protected from hydrolysis when inside its own hydrophobic droplets. Further, we found that methyl thioacetate protection from hydrolysis was also possible in droplets of hexane and in the membranes of nonanoic acid vesicles. Thus, the hydrophobic regions of prebiotic vesicles and early cell membranes could have offered a refuge for this energetic molecule, increasing its lifetime in close proximity to the reactions for which it would be needed. This model of early energy storage evokes an additional critical function for the earliest cell membranes.

  10. 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.

  11. 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.

  12. Predominant contribution of syntrophic acetate oxidation to thermophilic methane formation at high acetate concentrations.

    PubMed

    Hao, Li-Ping; Lü, Fan; He, Pin-Jing; Li, Lei; Shao, Li-Ming

    2011-01-15

    To quantify the contribution of syntrophic acetate oxidation to thermophilic anaerobic methanogenesis under the stressed condition induced by acidification, the methanogenic conversion process of 100 mmol/L acetate was monitored simultaneously by using isotopic tracing and selective inhibition techniques, supplemented with the analysis of unculturable microorganisms. Both quantitative methods demonstrated that, in the presence of aceticlastic and hydrogenotrophic methanogens, a large percentage of methane (up to 89%) was initially derived from CO(2) reduction, indicating the predominant contribution of the syntrophic acetate oxidation pathway to acetate degradation at high acid concentrations. A temporal decrease of the fraction of hydrogenotrophic methanogenesis from more than 60% to less than 40% reflected the gradual prevalence of the aceticlastic methanogenesis pathway along with the reduction of acetate. This apparent discrimination of acetate methanization pathways highlighted the importance of the syntrophic acetate-oxidizing bacteria to initialize methanogenesis from high organic loadings.

  13. The Effects of pH on the Growth and Aspect Ratio of Chicken Egg White Lysozyme Crystals Prepared in Different Buffers

    NASA Technical Reports Server (NTRS)

    Gibson, U. J.; Horrell, E. E.; Kou, Y.; Pusey, Marc

    2000-01-01

    We have measured the nucleation and aspect ratio of CEWL crystals grown by vapor diffusion in acetate, butyrate, carbonate, succinate, and phosphate buffers in a range of pH spanning the pK(sub a) of these buffers. The nucleation numbers drop off significantly in the vicinity of pK(sub a) for each of the buffers except the phosphate system, in which we used only the pH range around the second titration point(pK2). There is a concomitant increase in the sizes of the crystals. Some typical nucleation number results are shown. These data support and extend other observations. In addition, we have examined changes in aspect ratio which accompany the suppression of nucleation within each buffer system. The length of the face in the [001] direction was measured, and compared to the width of the (110) face in the [110] type directions. We find that while the aspect ratio of the crystals is affected by pH, it is dominated by a correlation with the size of the crystals. Small crystals are longer in the [0011 direction than crystals that are larger (higher pH within a buffer system). This relationship is found to hold independent of the choice of buffer. These results are consistent with those of Judge et al, who used a batch process which resulted in uniform sizing of crystals at each pH. In these experiments, we specifically avoid agitating the protein/salt buffer mixture when combining the two. This permits the formation of a range of sizes at a given pH. The results for a .05 M acetate 5% NaCl buffer are also shown. We will discuss these results in light of a growth model.

  14. Leuprolide acetate induces structural and functional recovery of injured spinal cord in rats

    PubMed Central

    Díaz Galindo, Carmen; Gómez-González, Beatriz; Salinas, Eva; Calderón-Vallejo, Denisse; Hernández-Jasso, Irma; Bautista, Eduardo; Quintanar, J Luis

    2015-01-01

    Gonadotropin-releasing hormone (GnRH) and its synthetic analog leuprolide acetate, a GnRH agonist, have neurotrophic properties. This study was designed to determine whether administration of leuprolide acetate can improve locomotor behavior, gait, micturition reflex, spinal cord morphology and the amount of microglia in the lesion epicenter after spinal cord injury in rats. Rats with spinal cord compression injury were administered leuprolide acetate or saline solution for 5 weeks. At the 5th week, leuprolide acetate-treated rats showed locomotor activity recovery by 38%, had improvement in kinematic gait and exhibited voiding reflex recovery by 60%, as compared with the 1st week. By contrast, saline solution-treated rats showed locomotor activity recovery only by 7%, but voiding reflex did not recover. More importantly, leuprolide acetate treatment reduced microglial immunological reaction and induced a trend towards greater area of white and gray matter in the spinal cord. Therefore, leuprolide acetate has great potential to repair spinal cord injury. PMID:26807118

  15. Leuprolide acetate induces structural and functional recovery of injured spinal cord in rats.

    PubMed

    Díaz Galindo, Carmen; Gómez-González, Beatriz; Salinas, Eva; Calderón-Vallejo, Denisse; Hernández-Jasso, Irma; Bautista, Eduardo; Quintanar, J Luis

    2015-11-01

    Gonadotropin-releasing hormone (GnRH) and its synthetic analog leuprolide acetate, a GnRH agonist, have neurotrophic properties. This study was designed to determine whether administration of leuprolide acetate can improve locomotor behavior, gait, micturition reflex, spinal cord morphology and the amount of microglia in the lesion epicenter after spinal cord injury in rats. Rats with spinal cord compression injury were administered leuprolide acetate or saline solution for 5 weeks. At the 5(th) week, leuprolide acetate-treated rats showed locomotor activity recovery by 38%, had improvement in kinematic gait and exhibited voiding reflex recovery by 60%, as compared with the 1(st) week. By contrast, saline solution-treated rats showed locomotor activity recovery only by 7%, but voiding reflex did not recover. More importantly, leuprolide acetate treatment reduced microglial immunological reaction and induced a trend towards greater area of white and gray matter in the spinal cord. Therefore, leuprolide acetate has great potential to repair spinal cord injury.

  16. Buffered local anesthetics and epinephrine degradation.

    PubMed

    Murakami, C S; Odland, P B; Ross, B K

    1994-03-01

    Lidocaine with epinephrine is currently the most common local anesthetic agent used for facial soft tissue surgery. This combination is generally safe and effective in providing complete anesthesia and adequate hemostasis. Because epinephrine is unstable at physiologic pH, the commercial preparation is formulated with a low pH (3.5-5.5). Unfortunately, this acidic pH causes significant pain during infiltration. To reduce pain, clinicians sometimes buffer acidic local anesthetic agents with sodium bicarbonate. However, little is known about the stability of epinephrine when the pH of epinephrine is clinically altered. Using high pressure liquid chromatography (HPLC), epinephrine levels were measured after the addition of sodium bicarbonate. Our results indicate a significant amount of epinephrine degradation occurs in some of these specimens. Recommendations regarding the use of buffered local anesthetic agents are made.

  17. 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.

  18. Simple buffers for 3D STORM microscopy.

    PubMed

    Olivier, Nicolas; Keller, Debora; Rajan, Vinoth Sundar; Gönczy, Pierre; Manley, Suliana

    2013-06-01

    3D STORM is one of the leading methods for super-resolution imaging, with resolution down to 10 nm in the lateral direction, and 30-50 nm in the axial direction. However, there is one important requirement to perform this type of imaging: making dye molecules blink. This usually relies on the utilization of complex buffers, containing different chemicals and sensitive enzymatic systems, limiting the reproducibility of the method. We report here that the commercial mounting medium Vectashield can be used for STORM of Alexa-647, and yields images comparable or superior to those obtained with more complex buffers, especially for 3D imaging. We expect that this advance will promote the versatile utilization of 3D STORM by removing one of its entry barriers, as well as provide a more reproducible way to compare optical setups and data processing algorithms.

  19. 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.

  20. Wintering bird response to fall mowing of herbaceous buffers

    USGS Publications Warehouse

    Blank, P.J.; Parks, J.R.; Dively, G.P.

    2011-01-01

    Herbaceous buffers are strips of herbaceous vegetation planted between working agricultural land and streams or wetlands. Mowing is a common maintenance practice to control woody plants and noxious weeds in herbaceous buffers. Buffers enrolled in Maryland's Conservation Reserve Enhancement Program (CREP) cannot be mowed during the primary bird nesting season between 15 April and 15 August. Most mowing of buffers in Maryland occurs in late summer or fall, leaving the vegetation short until the following spring. We studied the response of wintering birds to fall mowing of buffers. We mowed one section to 10-15 cm in 13 buffers and kept another section unmowed. Ninety-two percent of birds detected in buffers were grassland or scrub-shrub species, and 98% of all birds detected were in unmowed buffers. Total bird abundance, species richness, and total avian conservation value were significantly greater in unmowed buffers, and Savannah Sparrows (Passerculus sandwichensis), Song Sparrows (Melospiza melodia), and White-throated Sparrows (Zonotrichia albicollis) were significantly more abundant in unmowed buffers. Wintering bird use of mowed buffers was less than in unmowed buffers. Leaving herbaceous buffers unmowed through winter will likely provide better habitat for wintering birds. ?? 2011 by the Wilson Ornithological Society.