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Sample records for acetate buffer solution

  1. 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)

  2. 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.

  3. 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.

  4. 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.

  5. 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. PMID:25641961

  6. 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.

  7. 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. PMID:25063101

  8. 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)

  9. 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 ...

  10. Impact of freezing on pH of buffered solutions and consequences for monoclonal antibody aggregation.

    PubMed

    Kolhe, Parag; Amend, Elizabeth; Singh, Satish K

    2010-01-01

    Freezing of biologic drug substance at large scale is an important unit operation that enables manufacturing flexibility and increased use-period for the material. Stability of the biologic in frozen solutions is associated with a number of issues including potentially destabilizing pH changes. The pH changes arise from temperature-associated change in the pK(a)s, solubility limitations, eutectic crystallization, and cryoconcentration. The pH changes for most of the common protein formulation buffers in the frozen state have not been systematically measured. Sodium phosphate buffer, a well-studied system, shows the greatest change in pH when going from +25 to -30 degrees C. Among the other buffers, histidine hydrochloride, sodium acetate, histidine acetate, citrate, and succinate, less than 1 pH unit change (increase) was observed over the temperature range from +25 to -30 degrees C, whereas Tris-hydrochloride had an approximately 1.2 pH unit increase. In general, a steady increase in pH was observed for all these buffers once cooled below 0 degrees C. A formulated IgG2 monoclonal antibody in histidine buffer with added trehalose showed the same pH behavior as the buffer itself. This antibody in various formulations was subject to freeze/thaw cycling representing a wide process (phase transition) time range, reflective of practical situations. Measurement of soluble aggregates after repeated freeze-thaw cycles shows that the change in pH was not a factor for aggregate formation in this case, which instead is governed by the presence or absence of noncrystallizing cryoprotective excipients. In the absence of a cryoprotectant, longer phase transition times lead to higher aggregation. PMID:20039442

  11. 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.

  12. Role of the buffer solution in the chemical deposition of CdS films for CIGS solar cell applications

    NASA Astrophysics Data System (ADS)

    Lee, Sooho; Kim, Donguk; Baek, Dohyun; Hong, Byoungyou; Yi, Junsin; Lee, Jaehyeong; Park, Yong Seob; Choi, Wonseok

    2014-05-01

    In this work, the effects of NH4Ac on the structural and the electro-optical properties of CdS films were investigated. CdS thin films were deposited on soda-lime glass and indium-tin-oxide (ITO) coated glass from a chemical bath containing 0.025 M cadmium acetate, 0 M ~ 0.2 M ammonium acetate, 0.5 M thiourea, and ammonia. Cadmium acetate was the cadmium source, ammonium acetate served as a buffer, ammonia was the complexing agent, and thiourea was the source of sulfur. A commonl- available chemical bath deposition system was successfully modified to obtain precise control over the pH of the solution at 75 °C during the deposition. Chemically deposited CdS films were studied by using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), optical transmittance, and electrical resistivity measurements.

  13. Quantitative Screening of Agrochemical Residues in Fruits and Vegetables by Buffered Ethyl Acetate Extraction and LC-MS/MS Analysis.

    PubMed

    Jadhav, Manjusha R; Oulkar, Dasharath P; Shabeer T P, Ahammed; Banerjee, Kaushik

    2015-05-13

    A buffered ethyl acetate extraction method is proposed for the simultaneous analysis of 296 agrochemicals in a wide range of fruit and vegetable matrices by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimized quantity of acetate buffer (1% acetic acid + 0.5 g of sodium acetate per 10 g of sample) adjusted the pH of each test matrix to 5-6, which in turn significantly improved recoveries of acidic and basic compounds. The role of diethylene glycol (used in the evaporation step) on signal suppression of certain compounds was evaluated, and its quantity was optimized to minimize such an effect. The method was validated in grape, mango, drumstick, bitter gourd, capsicum, curry leaf, and okra as per the DG-SANCO/12571/2013 guidelines. Recoveries in the fortification range of 1-40 μg/kg were within 70-120% with associated relative standard deviations below 20% for most of the compounds. The method has potential for regulatory and commercial applications with a generic approach. PMID:25639652

  14. 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%. PMID:24878826

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

    PubMed

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

    2012-01-01

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

  16. 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.

  17. Superconducting films made by spin-coating of acetate solutions

    SciTech Connect

    Balachandran, U.; Poeppel, R.B. ); dos Santos, D.I.; Carvalho, C.L.; da Silva, R.R.; Aegerter, M.A. . Inst. de Fisica e Quimica)

    1990-12-01

    Metallic silver substrates were spin-coated with several layers of mixed acetate solutions containing bismuth, lead, strontium, calcium, and copper. The viscosities of the cation solutions were modified by the addition of polyvinyl alcohol. The films were heat treated at various temperatures in air, O{sub 2}, and 1% O{sub 2} (balance N{sub 2}) atmospheres. Bismuth cuprate films with transport critical current densities {approx}500 A/cm{sup 2} were obtained in this work. New conditions of coating and sintering have been tried to produce superconducting films.

  18. Stability of biodegradable waterborne polyurethane films in buffered saline solutions.

    PubMed

    Lin, Ying Yi; Hung, Kun-Che; Hsu, Shan-Hui

    2015-01-01

    The stability of polyurethane (PU) is of critical importance for applications such as in coating industry or as biomaterials. To eliminate the environmental concerns on the synthesis of PU which involves the use of organic solvents, the aqueous-based or waterborne PU (WBPU) has been developed. WBPU, however, may be unstable in an electrolyte-rich environment. In this study, the authors reported the stability of biodegradable WBPU in the buffered saline solutions evaluated by atomic force microscopy (AFM). Various biodegradable WBPU films were prepared by spin coating on coverslip glass, with a thickness of ∼300 nm. The surface AFM images of poly(ε-caprolactone) (PCL) diol-based WBPU revealed nanoglobular structure. The same feature was observed when 20% molar of the PCL diol soft segment was replaced by polyethylene butylenes adipate diol. After hydration in buffered saline solutions for 24 h, the surface domains generally increased in sizes and became irregular in shape. On the other hand, when the soft segment was replaced by 20% poly(l-lactide) diol, a meshlike surface structure was demonstrated by AFM. When the latter WBPU was hydrated, the surface domains appeared to be disconnected. Results from the attenuated total reflectance infrared spectroscopy and x-ray photoelectron spectroscopy indicated that the surface chemistry of WBPU films was altered after hydration. These changes were probably associated with the neutralization of carboxylate by ions in the saline solutions, resulting in the rearrangements of soft and hard segments and causing instability of the WBPU. PMID:26296357

  19. Process for making 90 K superconductors from acetate precursor solutions

    SciTech Connect

    Bolt, J.D.; Subramanian, M.A.

    1989-09-12

    This patent describes an improved process for preparing a superconducting composition having the formula MBa/sub 2/Cu/sub 3/O/sub chi/. In this process M is selected from the group consisting of Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu; chi is from about 6.5 to about 7.0; the composition having a superconducting transition temperature of about 90 {Kappa}. The process consisting essentially of: forming in acetic acid a mixture of MCC/sub 2/H/sub 3/O/sub 2//sub 3/, a barium acetate and copper acetate in an atomic ratio of M:Ba:Cu of about 1:2:3; heating the resulting mixture to boiling, and adding sufficient formic acid to dissolve any undissolved starting material while maintaining boiling; evaporating the solvent from the resulting solution to form a solid mass; heating the resulting material in an oxygen-containing atmosphere at a temperature from about 850{sup 0}C to about 925{sup 0}C for a time sufficient to form MBa/sub 2/Cu/sub 3/O/sub y/, where y is from about 6.0 to about 6.4; and maintaining the MBa/sub 2/Cu/sub 3/O/sub y/ in an oxygen-containing atmosphere while cooling for a time sufficient to obtained the desired product.

  20. Seed layer, solution concentration and thickness effects on CSD-derived La 2Zr 2O 7 buffer layers for coated conductors

    NASA Astrophysics Data System (ADS)

    Zhu, X. B.; Lei, H. C.; Shi, D. Q.; Zhang, L.; Wang, L.; Sun, Y. P.; Song, W. H.; Yang, Z. R.; Kim, J. H.; Zeng, R.; Dou, S. X.; Yang, J.; Gu, H. W.

    2007-12-01

    La2Zr2O7/NiW buffer layers as very promising buffer layers for coated conductors were fabricated by chemical solution deposition using cheap precursors, La-acetate and Zr-(IV) n-propoxide (70% w/w in n-propanol). The effects on the orientation and microstructure of La2Zr2O7 buffer layers, including seed layer, thickness and solution concentration, were investigated. The results showed that insertion of a seed layer could obviously improve the crystallization and orientation, and decrease of single layer thickness could also obviously improve the in-plane orientation. The results of all metalorganic depositions derived YBCO/CeO2/La2Zr2O7/NiW showed that the prepared La2Zr2O7 buffer layers were suitable for coated conductors using all metalorganic depositions.

  1. 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.

  2. Polymicrobial Biofilm Inhibition Effects of Acetate-Buffered Chitosan Sponge Delivery Device.

    PubMed

    Jennings, Jessica Amber; Beenken, Karen E; Parker, Ashley C; Smith, James Keaton; Courtney, Harry S; Smeltzer, Mark S; Haggard, Warren O

    2016-04-01

    Polymicrobial biofilm-associated implant infections present a challenging clinical problem. Through modifications of lyophilized chitosan sponges, degradable drug delivery devices for antibiotic solution have been fabricated for prevention and treatment of contaminated musculoskeletal wounds. Elution of amikacin, vancomycin, or a combination of both follows a burst release pattern with vancomycin released above minimum inhibitory concentration for Staphylococcus aureus for 72 h and amikacin released above inhibitory concentrations for Pseudomonas aeruginosa for 3 h. Delivery of a vancomycin, amikacin, or a combination of both reduces biofilm formation on polytetrafluoroethylene catheters in an in vivo model of contamination. Release of dual antibiotics from sponges is more effective at preventing biofilm formation than single-loaded chitosan sponges. Treatment of pre-formed biofilm with high-dose antibiotic release from chitosan sponges shows minimal reduction after 48 h. These results demonstrate infection-preventive efficacy for antibiotic-loaded sponges, as well as the need for modifications in the development of advanced materials to enhance treatment efficacy in removing established biofilm. PMID:26756211

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

    SciTech Connect

    Giordano, T.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 295C 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 (F{sub 3}CSO{sub 3}Na) was used as a supporting electrolyte. Stoichiometries and formation quotients for the complexes ZnCH{sub 3}COO{sup +}, Zn(CH{sub 3}COO){sub 2}, and Zn(CH{sub 3}COO){sub 3}{sup {minus}} were derived from the titration data by regression analysis. Stability constants at infinite dilution (K{sub n}) and other relevant thermodynamic quantities were calculated for these three complexes. 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.

  4. The Determination of the pH of Standard Buffer Solution: A Laboratory Experiment.

    ERIC Educational Resources Information Center

    Harris, K. R.

    1985-01-01

    Describes an experiment which shows: (1) how measurements of the reaction electromotive force for the cell (Pt/glass/NaCl(aq,m),buffer/AgCl/Ag/Pt) can be utilized in determining the absolute pH of the buffer; and (2) the demonstration of the use of the Debye-Huckel model of an electrolyte solution in solving an important electrochemical problem.…

  5. [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. PMID:24989301

  6. A Simple and Universal Method for Making up Buffer Solutions.

    ERIC Educational Resources Information Center

    Dennison, Clive

    1988-01-01

    Uses a method which involves weighing out an amount of the appropriate weak acid or base and dissolving it in distilled water close to the final volume. Solution is then titrated with strong acid or base to give the desired pH. Provides three examples. (MVL)

  7. 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.

  8. Investigation of passive films formed on the surface of alloy 690 in borate buffer solution

    NASA Astrophysics Data System (ADS)

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Wenli, Guo

    2015-10-01

    The passive film formed on the surface of the alloy 690 in borate buffer solution was studied by potentiodynamic curves and electrochemical impedance spectroscopy. With the increasing of the passivation potential, the corrosion resistance of the alloy 690 reduced. Moreover, the corrosion resistance of the passive film was the lowest in the vicinity of 0.6 VSCE. These results were supported by XPS and Mott-Schottky analyses. The corrosion resistance of the alloy 690 increased with the increasing of passivated potential in borate buffer solution with chloride ion. The chloride ion decreased corrosion resistance of the alloy 690 according to point defect model.

  9. Thick lanthanum zirconate buffer layers from water-based precursor solutions on Ni-5%W substrates

    SciTech Connect

    Narayanan, Vyshnavi; Lommens, Petra; De Buysser, Klaartje; Huehne, Ruben; Van Driessche, Isabel

    2011-11-15

    In this work, water-based precursor solutions suitable for dip-coating of thick La{sub 2}Zr{sub 2}O{sub 7} (LZO) buffer layers for coated conductors on Ni-5%W substrates were developed. The solutions were prepared based on chelate chemistry using water as the main solvent. The effect of polymer addition on the maximum crack-free thickness of the deposited films was investigated. This novel solution preparation method revealed the possibility to grow single, crack-free layers with thicknesses ranging 100-280 nm with good crystallinity and an in-plane grain misalignment with average FWHM of 6.55{sup o}. TEM studies illustrated the presence of nanovoids, typical for CSD-LZO films annealed under Ar-5%H{sub 2} gas flow. The appropriate buffer layer action of the film in preventing the Ni diffusion was studied using XPS. It was found that the Ni diffusion was restricted to the first 30 nm of a 140 nm thick film. The surface texture of the film was improved using a seed layer. - Graphical abstract: Thick LZO buffer layers from water-based precursor solutions were synthesized and their crystallinity, microstructure and buffer layer action were studied. The buffer layer action of the LZO layer was substantial to restrict the Ni penetration within 30 nm of a 140 nm thick film. Highlights: > LZO buffer layers with high thicknesses for use in coated conductors were prepared. > Prepared from water-based solutions. > Polymeric PVP increases the crack-free critical thickness of thick films. > Thick films showed good barrier action against Ni penetration. > Seed layers promote epitaxial growth of thick layers.

  10. 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

  11. 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

  12. 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

  13. EQUALIZING THE ELECTRIC FIELD INTENSITY WITHIN CHICK BRAIN IMMERSED IN BUFFER SOLUTION AT DIFFERENT CARRIER FREQUENCIES

    EPA Science Inventory

    Presented here are the numerical relationships between incident power densities that produce the same average electric field intensity within a chick brain half immersed in buffered saline solution and exposed to a uniform electromagnetic field at carrier frequencies of 50, 147, ...

  14. 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

  15. Corrosion behavior of ASTM A106 and AISI 316SS in KOH and nickel acetate solutions

    SciTech Connect

    Gonzalez, J.J.; Baron, E.; Saldeho, J.

    1999-11-01

    The present work is concerned with the corrosion behavior of ASTM A106 B grade and AISI 316 stainless steel in the presence of three different environments: a mixture or an emulsion formed by oil-KOH-nickel acetate solution, a KOH (40 wt. %) solution and a nickel acetate (14 wt. %) solution, which are representative fluids used during a PDVSA proprietary process for improving heavy crude oils. Corrosion rate measurements and stress corrosion cracking (SCC) behavior were evaluated through weight loss (in the laboratory and in situ measurements), and mechanical testing (constant load and slow strain rate tests). In the emulsion the corrosion rate was almost undetectable for both steels and the evidence suggested that no SCC had taken place. However, the corrosion rate of the carbon steel in 40wt.% KOH solution at 130 C was 2.8 mm/y, showing the presence of pitting corrosion. On the other hand, the stainless steel showed an undetectable corrosion rate. Though SCC was not observed in any of the materials tested in presence of KOH at both 30 and 130 C, a deterioration in the mechanical properties was found for the high temperature case for carbon steel. During nickel acetate solution tests at 130 C, the A 106 steel showed a relatively high corrosion rate (5.9 mm/y) and the formation of pits. For the stainless steel case, acetate solution had no corrosive effect whatsoever. This last environment offered no SCC susceptibility for any material at both temperatures tested.

  16. Chapter 21 Architecture of Hydrates and Local Structure of Acetic Acid Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Pu, Liang; Wang, Qing; Zhang, Yong; Miao, Qiang; Kim, Yang-Soo; Zhang, Zhibing

    The protonation and deprotonation phenomena and molecular association of solute molecule with water via intermolecular hydrogen bonding forming various hydration compounds are very common in aqueous solution and in biological cell in nature. In the aqueous solution, more complicated type of hydrogen bond, hydrogen-bonding rings, various kinds of hydration compounds (hydrates), and even hydrogen-bonding network can be expected. The nature of hydrogen bonding, the bonds networking, the rule in architecture of larger hydration compounds, deprotonation of acetic acid in solution, stability of the hydrated proton, and the local structure of its aqueous solution are the most fundamental problems to understanding solute molecule living style in aqueous solution. Hydrogen-bonding rings and network in the multi-hydrates of acetic acid monomer have been investigated by ab initio calculations, and ab initio molecular dynamics (CPMD) simulations on acetic acid monomer-water system were also performed to explore the local structure of acetic acid aqueous solution. More than hundreds of multi-hydrates have been selected as candidates during our calculations. The structural optimizations and energy calculations have been performed at the MP2/6-31+g (d, p) and MP4/6-31+g (d, p) levels which are adequate for our large hydrates calculations with reliable results and reasonable cost as we stated in the Section 2. The most stable structure of the smallest hydration compound of acetic acid monomer, i.e., acetic acid water dimer, has a four-membered head-on ring with the smallest dipole moment. To verify the existence of it, the infrared spectra experiment data were collected in the dilute CCl4/HAc and CCl4/H2O ratio condition. The hydroxyl (O-H) stretching vibrations in molecules of water, acetic acid, and the dimer are distinguished, for the dissolved species are isolated from each other by surrounded solvent molecules CCl4. The calculated and measured vibration frequencies are almost lain in line with 0.872 scaling. The four-, five-, and six-membered head-on rings are the most favorable in the small multi-hydrates with a stable planar structure and the side-on ring with a weak hydrogen-bonding interaction of C-H...Ow-H. The six-membered ring is most important in the large multi-hydrates and in the local structure of dilute solution also verified by our CPMD simulations. A larger ring of or more than seven-membered could no longer maintain the planar structure. Larger multi-hydrates of acetic acid monomer could be constructed from these basic building blocks. The strength order for the five kinds of bonds is in the descending order as C-O-H...Ow-H>Ow-H...Ow-H>CO...H-Ow>Ow-H...Oa-H>>C-H...Ow-H. The three hydroxyl bonds O-H in the hydrated proton could be divided into two types: one of the hydroxyl bonds is hydrogen bonded to the deprotonated oxygen of the acetic acid, other two to waters in the hydrate. The larger the RO-H becomes, the smaller the RO...H and the stronger the associated hydrogen bond are. The hydrated proton is stable and liberated from the deprotonated acetic acid in the large multi-hydrate with more complicit head-on ring. In small hydrates, the protonating hydrogen is shared partly by the acetic acid.

  17. 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. PMID:26888336

  18. 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.

  19. Novel post CMP cleaning using buffered HF solution and ozone water

    NASA Astrophysics Data System (ADS)

    Yeh, Ching-Fa; Hsiao, Chih-Wen; Lee, Wen-Shan

    2003-06-01

    Post chemical mechanical polishing (CMP) cleaning is a key process for copper (Cu) CMP in dual damascene interconnection technology. During the post CMP cleaning, it is an important issue to minimize organic and Cu contamination residues on the dielectric surface. This study proposed a novel post CMP cleaning using HAL buffer hydrofluoric (BHF) solution and ozone (O 3) water cleaning. The performance of the proposed cleaning technology was investigated and compared to conventional citric solution cleaning, which is currently used in post Cu CMP cleaning. From roughness, contamination residues and electrical characteristics, the proposed cleaning technology showed better performance than citric solution cleaning did. This excellent cleaning performance is attributed to the surface etching and contamination elimination effect of HAL BHF solution and O 3 water. Based on the experimental results, the proposed cleaning technology is feasible and superior to the conventional post CMP cleaning.

  20. Catalytic Deprotection of Acetals In Strongly Basic Solution Usinga Self-Assembled Supramolecular 'Nanozyme'

    SciTech Connect

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

    2007-07-26

    Acetals are among the most commonly used protecting groups for aldehydes and ketones in organic synthesis due to their ease of installation and resistance to cleavage in neutral or basic solution.[1] The common methods for hydrolyzing acetals almost always involve the use of either Broensted acid or Lewis acid catalysts.[2] Usually aqueous acids or organic solutions acidified with organic or inorganic acids have been used for reconversion of the acetal functionality to the corresponding carbonyl group; however, recently a number of reports have documented a variety of strategies for acetal cleavage under mild conditions. These include the use of Lewis acids such as bismuth(III)[3] or cerium(IV),[4, 5] functionalized silica gel, such as silica sulfuric acid[6] or silica-supported pyridinium p-toluene sulfonate,[7] or the use of silicon-based reagents such as TESOTf-2,6-Lutidine.[8] Despite these mild reagents, all of the above conditions require either added acid or overall acidic media. Marko and co-workers recently reported the first example of acetal deprotection under mildly basic conditions using catalytic cerium ammonium nitrate at pH 8 in a water-acetonitrile solution.[5] Also recently, Rao and co-workers described a purely aqueous system at neutral pH for the deprotection of acetals using {beta}-cyclodextrin as the catalyst.[9] Herein, we report the hydrolysis of acetals in strongly basic aqueous solution using a self-assembled supramolecular host as the catalyst. During the last decade, we have used metal-ligand interactions for the formation of well-defined supramolecular assemblies with the stoichiometry M{sub 4}L{sub 6}6 (M = Ga{sup III} (1 refers to K{sub 12}[Ga{sub 4}L{sub 6}]), Al{sup III}, In{sup III}, Fe{sup III}, Ti{sup IV}, or Ge{sup IV}, L = N,N{prime}-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) (Figure 1).[10] The metal ions occupy the vertices of the tetrahedron and the bisbidentate catecholamide ligands span the edges. The strong mechanical coupling of the ligands transfers the chirality from one metal center to the other, thereby requiring the {Delta}{Delta}{Delta}{Delta} or {Lambda}{Lambda}{Lambda}{Lambda} configurations of the assembly. While the 12- overall charge imparts water solubility, the naphthalene walls of the assembly provide a hydrophobic environment which is isolated from the bulk aqueous solution. This hydrophobic cavity has been utilized to kinetically stabilize a variety of water-sensitive guests such as tropylium,[11] iminium ions,[12] diazonium ions,[13] and reactive phosphonium species.[14] Furthermore, 1 has been used to encapsulate catalysts[15] for organic transformations as well as act as a catalyst for the 3-aza-Cope rearrangement of enammonium substrates[16] and the hydrolysis of acid-labile orthoformates.[17] Our recent work using 1 as a catalyst for orthoformate hydrolysis prompted our investigation of the ability of 1 to catalyze the deprotection of acetals (Scheme 1). With the ability of 1 to favor encapsulation of monocationic guests, we anticipated that the rates of acetal hydrolysis could be accelerated by stabilization of any of the cationic protonated intermediates along the mechanistic pathway upon encapsulation in 1. In contrast to the stability of 2,2-dimethoxypropane in H{sub 2}O at pH 10, addition of the acetal to a solution of 1 at this pH quickly yielded the products of hydrolysis (acetone and methanol). Addition of a strongly binding inhibitor for the interior cavity of 1, such as NEt{sub 4}{sup +} (log (K{sub a}) = 4.55), inhibited the overall reaction, confirming that 1 is active in the catalysis.

  1. Effect of acetic NaF solution on the corrosion behavior of stainless steel orthodontic brackets.

    PubMed

    Jang, Hee-Song; Son, Woo-Sung; Park, Soo-Byung; Kim, Hyung-Il; Yong, Hoon Kwon

    2006-06-01

    This study assessed the effect of acetic NaF solutions on stainless steel orthodontic brackets. Acetic acid was added to a 0.1% NaF solution to make two solutions, one with pH 3.5 and the other with pH 6. For the two different stainless steel brackets (Tomy, Dentaurum) used in this study, they had a similar elemental composition--except with Mo (molybdenum) in the Tomy bracket. The brackets were then immersed in the prepared test solutions for three days and their responses evaluated. In terms of hydrofluoric acid (HF) concentration, the 0.1%/pH 3.5 solution showed a high HF concentration at 227 ppm, while that of 0.1%/pH 6 solution was very low at 7 ppm. In terms of color change and element release, only the Dentaurum brackets in 0.1%/pH 3.5 solution showed an appreciable color change (deltaE* = 4.0) and released a great amount of elements (Fe, Cr, Ni, Mn) after three days. Otherwise, regardless of pH value and product, only minor color change (deltaE* < 1.0) and negligible element release occurred. In terms of surface modification, no visible changes in surface morphology were observed in any product after immersion in test solutions. PMID:16916238

  2. Assessment of the myotoxicity of pharmaceutical buffers using an in vitro muscle model: effect of pH, capacity, tonicity, and buffer type.

    PubMed

    Napaporn, J; Thomas, M; Svetic, K A; Shahrokh, Z; Brazeau, G A

    2000-01-01

    The purpose of the present study was to investigate the myotoxicity of three buffers containing carboxylic acid groups (i.e., acetate, succinate, and citrate) as a function of their pH, capacity, and tonicity. The myotoxicity of these buffers in the range of pH 2-6 and 0.001-0.1 M buffer capacity was assessed using cumulative creatine kinase (CK) release from an isolated rodent muscle model following injection. Phenytoin and 0.9% NaCl injection were used as positive and negative controls, respectively. Buffer solutions were prepared. A lower pH and higher buffer capacity was linked to increased myotoxicity for the acetate buffers. However, for succinate and citrate buffers, pH appeared to influence the extent of myotoxicity, whereas buffer capacity did not seem to have an effect. When either NaCl or trehalose was used as a tonicity-adjusting agent at pH 6, isotonic 0.01 M buffer solutions dramatically lowered the cumulative CK release compared to those that were not isotonic. Isotonic succinate buffers displayed the lowest myotoxicity, whereas citrate buffers displayed the highest values. Citrate buffers containing three carboxylic acid groups showed higher myotoxicity than succinate buffers and acetate buffers at 0.001 and 0.01 M buffer capacities, whereas acetate buffer produced higher cumulative CK release than citrate and succinate buffers at 0.1 M buffer capacity. The myotoxicity of pharmaceutical buffers containing carboxylic acid groups appears to be directly affected by lowering the pH of the solution. PMID:10669926

  3. 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.

  4. 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. PMID:25768227

  5. A resin-buffered nutrient solution for controlling metal speciation in the algal bottle assay.

    PubMed

    Verheyen, L; Merckx, R; Smolders, E

    2012-06-15

    Metal speciation in solution is uncontrolled during algal growth in the traditional algal bottle assay. A resin-buffered nutrient solution was developed to overcome this problem and this was applied to test the effect of chloride (Cl⁻) on cadmium (Cd) uptake. Standard nutrient solution was enriched with 40 mM of either NaNO₃ or NaCl, and was prepared to contain equal Cd²⁺ but varying dissolved Cd due to the presence of CdCl(n)(2-n) complexes. Both solutions were subsequently used in an algal assay in 100 mL beakers that contained only the solution (designated "-R") or contained the solution together with a cation exchange sulfonate resin (2 g L⁻¹, designated "+R") as a deposit on the bottom of the beaker. Pseudokirchneriella subcapitata was grown for 72 h (1.4 × 10⁵-1.4 × 10⁶ cells mL⁻¹) in stagnant solution and shaken three times a day. Growth was unaffected by the presence of the resin (p>0.05). The Cd concentrations in solution of the -R devices decreased with 50-58% of initial values due to Cd uptake. No such changes were found in the +R devices or in abiotic controls. Cd uptake was unaffected by either NaNO₃ or NaCl treatment in the +R device, confirming that Cd²⁺ is the preferred Cd species in line with the general concept of metal bioavailability. In contrast, Cd uptake in the -R devices was two-fold larger in the NaCl treatment than in the NaNO₃ treatment (p<0.001), suggesting that CdCl(n)(2-n) complexes are bioavailable in this traditional set-up. However this bioavailability is partially, but not completely, an apparent one, because of the considerable depletion of solution ¹⁰⁹Cd in this set-up. Resin-buffered solutions are advocated in the algal bottle assay to control trace metal supply and to better identify the role of metal complexes on bioavailability. PMID:22447105

  6. 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)

  7. 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.

  8. 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. PMID:16854269

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

    PubMed

    Navarro-González, R; Negrón-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. PMID:11539119

  10. 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.

  11. 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.

  12. Localized corrosion of mild steel in base solutions containing sodium sulfide. Influence of pH and sodium acetate addition

    SciTech Connect

    Vasquez, D.; Arvia, A.J.; Salvarezza, R.C.; Videla, H.A.

    1984-08-01

    This paper presents a study of the role played by sulfide, hydroxyl, and acetate ions in solution to explain pit initiation and growth on mild steel. Potentiostatic and potentiodynamic techniques described in previous publications were used.

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

    SciTech Connect

    Paranthaman, Mariappan Parans; Qiu, Xiaofeng; Kim, Kyunghoon; Shi, D.; Zhang, Yifei; Li, Xiaoping; Sathyamurthy, Srivatsan; Thieme, C. L. H.; Rupich, M. W.

    2010-01-01

    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 CeO2 cap/YSZ barrier/Y2O3 seed on Ni-5%W metal tape. In the present work, we have identified CeO2 buffer layer as a potential replacement for Y2O3 seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of CeO2 (both 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 CeO2 phase with slightly improved out-of-plane texture compared to the texture of underlying Ni-W substrates can be achieved in pure, undoped CeO2 samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO2 seeds using sputtering. Both sputtered CeO2 cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO2/Ni-5W substrates. High critical currents per unit width, Ic of 264 A/cm (critical current density, Jc of 3.3 MA/cm2) at 77 K and 0.01 T was achieved for 0.8 m thick MOD-YBCO films grown on MOD-CeO2 seeds. These results indicate that CeO2 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.

  14. 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.

  15. 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.

  16. 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 725?m long consisting of a 22-?m-thick PMN-PT layer and a 6-?m-thick tin layer exhibited a mass detection sensitivity ?m /?f=-3210-12g/Hz and a concentration sensitivity of better than 100cells/ml in less than 1ml of liquid.

  17. 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. PMID:27009506

  18. Labile synthetic cadmium complexes are not bioavailable to Pseudokirchneriella subcapitata in resin buffered solutions.

    PubMed

    Verheyen, L; Merckx, R; Smolders, E

    2012-11-15

    The Free Ion Activity Model (FIAM) predicts that cadmium (Cd) uptake by organisms is identical for solutions with the same free Cd(2+) concentration and inorganic composition. Clear exceptions to the FIAM have been shown for Cd uptake by plant roots, periphyton and human cells where labile Cd complexes increase bioavailability and which has been attributed to their role in enhancing Cd diffusion towards the uptake cells. Here, we assessed the role of labile Cd complexes on Cd uptake by algae, for which diffusion limitations should be less pronounced due to their smaller size. Long-term (3 days) Cd uptake by the green algae Pseudokirchneriella subcapitata was measured in resin buffered solutions with or without synthetic ligands and at three Cd(2+) ion activities (pCd 8.2-5.7). The free Cd(2+) activity was maintained during the test using a metal-selective resin located in the algal bottles. Total dissolved Cd increased up to 35-fold by adding the synthetic ligands at constant Cd(2+) activity. In contrast, Cd uptake by algae increased maximally 2.8 fold with increasing concentration of the synthetic ligands and the availability of the complexes were maximally 5.2% relative to Cd(2+) for NTA and CDTA complexes. It is concluded that labile Cd complexes do not greatly enhance Cd bioavailability to the unicellular algae and calculations suggest that Cd transport from solution to these small cells is not rate limiting. PMID:22903064

  19. Aluminum elution and precipitation in glass vials: effect of pH and buffer species.

    PubMed

    Ogawa, Toru; Miyajima, Makoto; Wakiyama, Naoki; Terada, Katsuhide

    2015-02-01

    Inorganic extractables from glass vials may cause particle formation in the drug solution. In this study, the ability of eluting Al ion from borosilicate glass vials, and tendencies of precipitation containing Al were investigated using various pHs of phosphate, citrate, acetate and histidine buffer. Through heating, all of the buffers showed that Si and Al were eluted from glass vials in ratios almost the same as the composition of borosilicate glass, and the amounts of Al and Si from various buffer solutions at pH 7 were in the following order: citrate > phosphate > acetate > histidine. In addition, during storage after heating, the Al concentration at certain pHs of phosphate and acetate buffer solution decreased, suggesting the formation of particles containing Al. In citrate buffer, Al did not decrease in spite of the high elution amount. Considering that the solubility profile of aluminum oxide and the Al eluting profile of borosilicate glass were different, it is speculated that Al ion may be forced to leach into the buffer solution according to Si elution on the surface of glass vials. When Al ions were added to the buffer solutions, phosphate, acetate and histidine buffer showed a decrease of Al concentration during storage at a neutral range of pHs, indicating the formation of particles containing Al. In conclusion, it is suggested that phosphate buffer solution has higher possibility of forming particles containing Al than other buffer solutions. PMID:24261406

  20. Molecular Mechanism of Specific Ion Interactions Between Alkali Cations and Acetate Anion in Aqueous Solution: A Molecular Dynamics Study

    SciTech Connect

    Annapureddy, Harsha V.; Dang, Liem X.

    2012-06-28

    Specific ion interactions between the alkali cations (i.e., Li+, Na+ and K+) and an acetate anion in aqueous solution were studied using molecular dynamics simulation techniques and polarizable potential models. The ions-acetate systems were used as a model for understanding the interactions between ions and protein surfaces. We computed free energy profiles for different ion pairs using constrained mean force methods. Upon analyzing the computed free energy profiles for the Na+/K+-acetate ion-pairs, we observed a deeper contact ion minimum and also a larger association constant for the Na+-acetate pair compared to the corresponding K+-acetate pair. These observations help to demonstrate the preferential binding of Na+ over K+ to protein surfaces.

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

    PubMed

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

    2014-06-20

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

  2. Influence of Structure Breaking and Structure Forming Ions on the Dissociation Mechanism of Acetic Acid in Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Escriñá, J. A.; Bañón, M. L.; González-Velasco, J.

    1988-02-01

    Using a rotating disc electrode, the dissociation rate of acetic acid in various aqueous electrolyte solutions is studied. Li+ , Cs+ and (CH3)4N+ at 1 M concentration considerably modify the activation enthalpy and entropy of the reaction. Evidently the interaction between the cations and water influences the dissociation mechanism of the weak acid. In the presence of 1 molar Li+ the activated complex of acetic acid seems to contain only one water molecule instead of two in the other cases.

  3. THE EFFECT OF THE PH OF PH BUFFERED NUTRIENT SOLUTIONS ON NICKEL HYPERACCUMULATION BY ALYSSUM CORSICUM AND BERKHEYA CODDII

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is hypothesized that plant hyperaccumulation of Ni evolved as a defense mechanism against diseases and insects. Two hyperaccumulators, Alyssum corsicum and Berkheya coddii, were compared to cabbage (Brassica oleracea) grown in MES-HEPES buffered nutrient solutions and maintained at four pH levels...

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

    PubMed Central

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

    2016-01-01

    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. PMID:26899243

  5. 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.

  6. 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

    2016-01-01

    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-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. PMID:26899243

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

    PubMed Central

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

    2006-01-01

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

  8. 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.

  9. 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.

  10. 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. PMID:25852326

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

    NASA Astrophysics Data System (ADS)

    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 cm2 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.

  12. 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...

  13. 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.

  14. Production of ethyl acetate from dilute ethanol solutions by Candida utilis

    SciTech Connect

    Armstrong, D.W.; Martin, S.M.; Yamazaki, H.

    1984-01-01

    The conversion of ethanol to ethyl acetate has an advantage as a method of ethanol recovery since ethyl acetate is amenable to simple solvent extraction. The potential of Candida utilis in this conversion was studied. The kinetics of accumulation of ethanol and ethyl acetate in glucose-grown C. utilis showed that ester formation resulted from ethanol utilization under appropriate aeration and was inhibited by Fe/sup 3 +/ supplementation. Candida utilis converted ethanol to ethyl acetate optimally at pH 5.0-7.0. The five-hour rate of ester production increased as the ethanol concentration increased to 10 g/L, and rapidly declined to zero at concentrations exceeding 35 g/L. Thus, C. utilis has potential to recover dilute ethanol in the form of ethyl acetate.

  15. High-performance polymer solar cells with solution-processed and environmentally friendly CuOx anode buffer layer.

    PubMed

    Xu, Qi; Wang, Fuzhi; Tan, Zhan'ao; Li, Liangjie; Li, Shusheng; Hou, Xuliang; Sun, Gang; Tu, Xiaohe; Hou, Jianhui; Li, Yongfang

    2013-11-13

    Highly efficient polymer solar cells (PSCs) are demonstrated by introducing environmentally friendly CuOx as hole extraction anode buffer layer. The CuOx buffer layer is prepared simply via spin-coating 1,2-dichlorobenzene solution of Copper acetylacetonate on the ITO substrate and thermal transformation (at 80 C) in air. Remarkable improvements in the open-circuit voltage (Voc) and short-circuit current density (Jsc) of the PSCs could be achieved upon the introduction of CuOx buffer layer. The study about the effect of CuOx interfacial layer on the device resistances demonstrates that insertion of CuOx layer can decrease the whole resistance of the PSCs. For the devices based on P3HT:PCBM, the power conversion efficiency (PCE) was increased from 2.8% (the reference device without buffer layer) to 4.1% via introduction of CuOx hole extraction layer. The PCE of the PSC was further increased to 6.72% when ICBA used as an alternative acceptor to PCBM. The much higher PCE of 7.14% can be achieved by adopting PBDTTT-C, a low band gap conjugated polymer, as donor material. The results demonstrate that CuOx has great potential as a hole extraction material for highly efficient PSCs. PMID:24094978

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

    PubMed

    Cristofoletti, Rodrigo; Dressman, Jennifer B

    2016-06-01

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

  17. 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 Framework Directive (WFD) 2000/60, but a practical necessity for the safeguarding of public health and ecosystem health, in general. The present study aims at developing a simple methodology for assessing spatial distribution characteristics of pollution in Erymanthos catchment. Pollution loads at various sites in Erymanthos watershed were illustrated with Geographical Information System (GIS). Flow rates of Erymanthos River were also taken into consideration. Based on previous studies, in situ river discharges have been compared to simulated discharges in order to calibrate the rainfall-runoff model ENNS which can then predict future scenarios regarding the river flow rates with consideration of climate change effects. The goal of this study is to detect the pertinent points and suggest a) suitable buffer zones in areas with high pollution risk and b) simple technical works in order to prevent the main channel of Erymanthos River from direct polluting discharges. The above systems could also act supportively in groundwater enrichment, forest protection and soil erosion prevention. Authors believe that the results of the study could assist authorities and engineers to design and develop strategies of improving river water quality and safeguarding public health. The proposed measures may be applicable to other catchments as well.

  18. 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 observed. Similarly, glycine and mannitol, two widely used bulking agents, inhibited buffer component crystallization only when retained amorphous. In addition to stabilizing the active pharmaceutical ingredient, lyoprotectants may prevent solution pH shift by inhibiting buffer crystallization.

  19. An experimental determination of ferrous chloride and acetate complexation in aqueous solutions to 300[degrees]C

    SciTech Connect

    Palmer, D.A. ); Hyde, K.E. )

    1993-04-01

    Reliable thermodynamic information on the stability of ferrous chloride complexes at high temperatures is important to evaluations of iron transport in hydrothermal fluids, and to the power industry for iron corrosion and transport in the water/steam cycle. The formation of the monochloroiron(II) complex, FeCl[sup +], was studied potentiometrically from 125 to 295[degrees]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[degrees]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[sup +] 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[degrees]C. 40 refs., 12 figs., 5 tabs.

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

    PubMed

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

    2011-05-26

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

  1. Impact of inorganic buffering ions on the stability of Fe(vi) in aqueous solution: role of the carbonate ion.

    PubMed

    Kolář, Michal; Novák, Petr; Šišková, Karolína M; Machala, Libor; Malina, Ondřej; Tuček, Jiří; Sharma, Virender K; Zbořil, Radek

    2016-02-01

    An iron compound of +6 oxidation state (Fe(VI)O4(2-), Fe(vi)) is a green molecule for various applications (water oxidation catalyst, organic transformation for synthesis, and water remediation agent). However, its use is hindered because of its inherent decay in aqueous solution. This study presents a systematic kinetics investigation of the decay of ferrate(vi) in the presence of inorganic buffering ions (borate, phosphate, and carbonate) at a pH range from 6.0 to 9.0. When the heterogeneous decay of Fe(vi) on ferric products was inhibited by phosphate, detailed kinetic analysis revealed that the carbonate anion enhanced the Fe(vi) decay rate, compared to phosphate and borate ions. The order of the Fe(vi) decay rate under neutral solution conditions was carbonate > phosphate ≥ borate. In alkaline solution, the decay rates of Fe(vi) were similar for the studied buffering ions. The decay of Fe(vi) in the presence of the carbonate ion was described by mixed first- and second-order kinetics and the first-order rate constant (k1') had a linear relationship with the concentration of the carbonate ion at a neutral pH (k1' = 0.023 + 3.54 × [carbonate] L mol(-1) s(-1)). The analysis of the Fe(vi) decay intermediates/products (˙O2(-), H2O2, and O2) suggests similar decay pathways in the presence of different buffering anions. The impact of carbonate ions on the size of the nanoparticles of the Fe(iii) precipitate, the final reduced form of Fe(vi), was studied using transmission electron microscopy, (57)Fe Mössbauer spectroscopy, and magnetization measurements. The results indicated that carbonate ions induce the formation of ultrasmall iron(iii) oxyhydroxide nanoparticles (<5 nm), which apparently contribute to increased decay of Fe(vi) due to their larger specific surface area. The described homogeneous reaction of carbonate with Fe(vi) has important implications in the efficiency of environmental Fe(vi) applications. On the other hand, the observed low reactivity of borate with Fe(vi) demonstrates that borate is the least reactive buffer in studies of Fe(vi) reactivity in neutral solutions. PMID:26790819

  2. Robust Benzo[g, h, i ]perylenetriimide Dye-Sensitized Electrodes in Air-Saturated Aqueous Buffer Solution.

    PubMed

    Chen, Hung-Cheng; Williams, René M; Reek, Joost N H; Brouwer, Albert M

    2016-04-11

    Highly electron deficient benzo[ghi]perylenetriimide (BPTI) chromophores were persistently anchored to a metal oxide electrode surface and reversible formation of their radical anions was shown in air-saturated aqueous buffer solution. Our results show a very low reaction-rate constant of BPTI(.-) with O2 (k=1.92±0.05×10(-2)  s(-1) ). BPTI is a robust chromophore that can be used as the electron acceptor in molecule-based artificial photosynthetic devices for direct water splitting in aqueous phase. PMID:26928886

  3. 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.

  4. Interfacial energetics of globularblood 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 101000?kDa confirm that interfacial energetics of protein adsorption to a hydrophobic solid/aqueous-buffer (solidliquid, SL) interface are not fundamentally different than adsorption to the waterair (liquidvapour, 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 ?a of buffered-protein solutions on methyl-terminated, self-assembled monolayer surfaces show that maximum advancing spreading pressure, ?amax, falls within a relatively narrow 10

  5. 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

    2016-04-01

    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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Ink-jet printing of SrTiO3 buffer layers from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Pollefeyt, G.; Clerick, S.; Vermeir, P.; Feys, J.; Hühne, R.; Lommens, P.; Van Driessche, I.

    2014-09-01

    In this work, fully a-axis oriented SrTiO3 thin films were synthesized by ink-jet printing of water-based precursor inks. The developed precursor solution or ‘ink’ was optimized in terms of rheology, leading to the ejection of single droplets showing a maximum contact angle of 12° on (100) oriented single crystal LaAlO3 substrates. By using the appropriate ink-jet deposition parameters and thermal treatment, well-textured and dense SrTiO3 films of 130 nm thickness were obtained. The biaxial texture is maintained up to the surface of the films, leading to the formation of (h00)-oriented terraces. As shown by transmission electron microscopy, excellent texture transfer was achieved from the SrTiO3 film to the YBa2Cu3O7 - δ layer deposited by pulsed laser deposition. Outstanding superconducting properties were obtained with critical current densities up to 3.6 MA cm-2 in self-field at 77 K, demonstrating that these sustainable SrTiO3 films meet the requirements to be used as growing template for high quality superconducting coatings.

  11. Photochemically generated stable cation radical of phenothiazine aggregates in mildly acid buffered solutions.

    PubMed

    Rodrigues, Tiago; dos Santos, Carolina G; Riposati, Alessandra; Barbosa, Leandro R S; Di Mascio, Paolo; Itri, Rosangela; Baptista, Maurício S; Nascimento, Otaciro R; Nantes, Iseli L

    2006-06-29

    This work characterizes, for the first time, the photochemical behavior of the antipsychotic drugs thioridazine (TR), trifluoperazine (TFP), and fluphenazine (FP) influenced by the aggregation state of the molecules. Samples of monomeric and aggregated forms of phenothiazines were submitted to 20 min of irradiation at 254 nm for intervals of 1, 5, 10, 15, 20, or 25 days. In high phenothiazine concentrations, the irradiation led to the appearance of absorbance bands in the visible region peaking at 633 nm for TR and 509 nm for FP and TFP. In the dark, at room temperature and at 4 degrees C, these bands disappeared, after approximately 15 and approximately 60 min, respectively, but reappeared after a new irradiation session. These visible bands were assigned to stable cation radicals that were characterized by direct EPR measurements and by flash photolysis. Photogenerated stable cation radicals in the phenothiazine aggregates at room temperature are formed probably due to the stacking of the thiazine phenyl moieties. For the monomeric forms of phenothiazines, the spectral changes observed during the irradiation suggested the formation of sulfoxide and hydroxylated derivates. Oxidized derivates were detected by mass spectrometry of the aggregated forms of phenothiazines (>100 microM) only in the samples irradiated for more than 20 days. In contrast, monomeric phenothiazines were totally converted to the oxidized forms after 20 min of irradiation. Surface tension measurements of phenothiazines revealed that, in concentrations above 100 microM, the drugs formed aggregates. In the case of TR, small-angle X-ray scattering measurements indicated that this compound forms large lamellar-like aggregates in aqueous solutions. PMID:16800546

  12. Experimental determination of portlandite solubility in H sub 2 O and acetate solutions at 100-350C and 500 bars: Constraints on calcium hydroxide and calcium acetate complex stability

    SciTech Connect

    Seewald, J.S.; Seyfried, W.E. Jr. )

    1991-03-01

    The solubility of portlandite was measured in H{sub 2}O and aqueous acetate solutions of varying concentration (1-10 mmolal) at temperatures from 100-350C and 500 bars pressure. Dissolved Ca concentrations increased with decreasing temperature and increasing dissolved acetate concentration. Using known thermodynamic data for portlandite, H{sup +}, OH{sup {minus}}, Ca{sup ++}, CH{sub 3}COO{sup {minus}}, CH{sub 3}COOH{sup 0}, and H{sub 2}O{sub (1)}, stability constants for CaOH{sup +} and CaCH{sub 3}COO{sup +} complexes were determined. These results indicate that the stabilities of CaOH{sup 1} and CaCH{sub 3}COO{sup 1} complex increase with increasing temperature. In the acetate-free experiments, CaOH{sup +} is the dominant form of dissolved Ca in equilibrium with portlandite at 100-350C and 500 bars, while in the acetate-rich experiments (10 mmolal acetate), Ca{sup ++} and CaOH{sup +} are the dominant forms of Ca in equilibrium with portlandite at low temperature (100-200C) and CaCH{sub 3}COO{sup +} and CaOH{sup +} are the dominant forms at relatively high temperature (200-350C). Metal-acetate complexing has long been suggested as an important mechanism for mobilizing base metals during the formation of ore deposits in organic-rich environments. Due to the stability of CaCH{sub 3}COO{sup +} complex in Ca-bearing fluids at elevated temperatures and pressures, however, the effectiveness of dissolved acetate to enhance base metal sulfide solubility is limited.

  13. 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 RMGIC luting cement was significantly higher than traditional GIC luting cement for all core buildup materials except, for silver amalgam core buildup material. RMGIC core material showed highest shear bond strength values followed by Composite resin, GI Silver Reinforced, GI and Silver Amalgam core materials irrespective of luting cements. PMID:26436055

  14. 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.

  15. The preparation of accelerator targets by the evaporation of acetate-organic solutions in the presence of NH/sub 3/ gas

    SciTech Connect

    Cai, S.Y.; Ghiorso, A.; Hoffman, D.C.

    1987-03-01

    The chemical methods described in this paper have been developed for preparation of isotopic targets for bombardment by accelerator-produced ions. Three systems are compared: nitrate-, chloride-, and acetate-organic solutions. The best method was found to be the metallic acetate-organic solution system, evaporated onto the substrate in the presence of ammonia gas. A detailed procedure is given for this method. The targets obtained by the acetate-organic solution system are uniform and adherent. The hydroxide forms fine crystals of good quality for target thicknesses from a few ..mu..g/cm/sup 2/ to several mg/cm/sup 2/. Thicknesses up to 5 mg/cm/sup 2/ of Eu as the oxide were obtained by this method. The process is simple and fast. 18 refs., 1 tab.

  16. 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.

  17. Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes.

    PubMed

    Arthanareeswaran, G; Thanikaivelan, P; Jaya, N; Mohan, D; Raajenthiren, M

    2007-01-01

    A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Chromium salts are largely used in various industries including leather-manufacturing industry. Ultrafiltration processes are largely being applied for macromolecular and heavy metal ion separation from aqueous streams. Cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes were prepared by precipitation phase inversion technique in 100/0, 90/10, 80/20 and 70/30% polymer blend compositions and subjected to the rejection of chromium at different concentrations such as 200, 400, 600, 800 and 1000 ppm with a water-soluble macroligand (polyvinylalcohol). Factors affecting the percentage rejection and permeate flux such as pH, concentration of solute, concentration of PVA, transmembrane pressure and composition of blend membranes were investigated. It was found that percentage rejection improved at a pH 6 and a macroligand concentration of 2 wt.%. The transmembrane pressure and concentration of solute also have an effect on the separation and product rate efficiencies of the blend membranes. PMID:16860465

  18. Repassivation behavior of 316L stainless steel in borate buffer solution: Kinetics analysis of anodic dissolution and film formation

    NASA Astrophysics Data System (ADS)

    Xu, Haisong; Sun, Dongbai; Yu, Hongying

    2015-12-01

    The repassivation behavior of metals or alloys after oxide film damage determines the development of local corrosion and corrosion resistance. In this work, the repassivation kinetics of 316L stainless steel (316L SS) are investigated in borate buffer solution (pH 9.1) by using the abrading electrode technique. The current densities flowing from bare 316L SS surface are measured by potentiostatic method and analyzed to characterize repassivation kinetics. The initial stages of current decay (t < 500 ms) are discussed according to a film growth model, which describes the initial current transient should be divided into substrate dissolution current and passive film formation current based on Avrami kinetics. Then the two independent components are analyzed individually. The film formation rate and the thickness of film are compared in different applied potential. It is shown that anodic dissolution dominates the repassivation for a short time during the early times, and a higher applied potential will promote the anodic dissolution of metal. The film growth rate increases slightly with increasing in potential. Correspondingly, increase in applied potential from 0 VSCE to 0.8 VSCE results in thicker monolayer, which covers the whole bare surface at the time of θ = 1. The electric field strengths through the thin passive film could reach 3.97 × 106 V cm-1.

  19. Corrosion Behavior of Ultra-fine Grained 1050 Aluminum Alloy Fabricated by ARB Process in a Buffer Borate Solution

    NASA Astrophysics Data System (ADS)

    Fattah-alhosseini, A.; Gashti, S. O.

    2015-09-01

    Accumulative roll bonding (ARB) has been used as a severe plastic deformation process for the industrial production of ultra-fine grained (UFG) and nano-crystalline sheets with excellent mechanical properties. In the present study, the effect of the ARB process on the corrosion behavior of UFG and nano-crystalline 1050 aluminum alloy in a buffer borate solution (pH 5.5) has been investigated. The result of microhardness tests revealed that microhardness values increase with an increasing number of ARB cycles. A sharp increase in microhardness is seen after three ARB cycles, whereas moderate additional increases are observed afterward for up to nine cycles. Also, the XRD results showed that the mean crystallite size decreased to about 91 nm after nine cycles. The potentiodynamic plots show that as a result of ARB, the corrosion behavior of the UFG and nano-crystalline specimens improves, compared to the annealed 1050 aluminum alloy. Moreover, electrochemical impedance spectroscopy measurements showed that the polarization resistance increases with an increasing number of ARB cycles.

  20. Diffusion of 1-Ethyl-3-methyl-imidazolium Acetate in Glucose, Cellobiose, and Cellulose Solutions

    PubMed Central

    2014-01-01

    Solutions of glucose, cellobiose and microcrystalline cellulose in the ionic liquid 1-ethyl-3-methyl-imidazolium ([C2mim][OAc]) have been examined using pulsed-field gradient 1H NMR. Diffusion coefficients of the cation and anion across the temperature range 2070 C have been determined for a range of concentrations (015% w/w) of each carbohydrate in [C2mim][OAc]. These systems behave as an ideal mixture of free ions and ions that are associated with the carbohydrate molecules. The molar ratio of carbohydrate OH groups to ionic liquid molecules, ?, is the key parameter in determining the diffusion coefficients of the ions. Master curves for the diffusion coefficients of cation, anion and their activation energies are generated upon which all our data collapses when plotted against ?. Diffusion coefficients are found to follow an Arrhenius type behavior and the difference in translational activation energy between free and associated ions is determined to be 9.3 0.9 kJ/mol. PMID:24405090

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  2. 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.

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

    PubMed

    Taha, Mohamed; Lee, Ming-Jer

    2013-06-28

    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. PMID:23822250

  4. 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. PMID:24229393

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

    PubMed

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

    2013-09-17

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

  6. SEMICONDUCTOR MATERIALS: Morphology dependence of TiO2 nanotube arrays on anodization variables and buffer medium

    NASA Astrophysics Data System (ADS)

    Xin, Wen; Meng, Cao; Jie, Wu; Junchao, Tao; Yan, Sun; Ning, Dai

    2010-06-01

    Vertically oriented TiO2 nanotube arrays were prepared by potentiostatic anodization of Ti foils in HF/acetic acid (HAC) aqueous solution. Anodization variables including anodization electrolyte concentration, anodization voltage, anodization time and buffer medium can be chosen and adjusted to manipulate the nanotube arrays to give the required length and morphology.

  7. 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. PMID:26684416

  8. 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. PMID:26880196

  9. 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

  10. High performance perovskite solar cell via multi-cycle low temperature processing of lead acetate precursor solutions.

    PubMed

    Singh, Trilok; Miyasaka, Tsutomu

    2016-04-01

    A lead acetate-based precursor, as a lead source in CH3NH3PbI3 perovskite, showed potential in rapidly (<60 seconds) forming homogeneous films with a very smooth interface and large grain growth at relatively low temperatures via multi-step coating. Cells based on this method exhibited high power conversion efficiency beyond 17% with good reproducibility. PMID:26958661

  11. 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.

    2016-02-01

    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.

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

    PubMed

    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. Graphical Abstract ᅟ. PMID:26919868

  13. 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

  14. Critical review of the methods used to measure the apparent dissociation constant and ligand purity in Ca2+ and Mg2+ buffer solutions.

    PubMed

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

    2006-11-01

    Using simulated Ca2+ and Mg2+ buffers, methods proposed to measure both ligand purity and the apparent dissociation constant (Kapp) were investigated regarding (1) predicted accuracy of both parameters and (2) generality of the solution. The Bers' Ca2+ macroelectrode method [Bers, D. M., 1982 A simple method for the determination of free [Ca] in Ca-EGTA solutions Am. J. Physiol. 242, C404-C408] cannot be used with Mg2+ -macroelectrodes and is partly arbitrary since the linear part of the Scatchard plot is judged subjectively. Iterative methods have therefore been introduced. Iteration based on Bers' method or the lumped interference in the Nicolsky-Eisenman equation also failed with Mg2+ macroelectrodes. The Oiki et al., method [Oiki, S., Yomamoto, T., Okada, Y., 1994. Apparent stability constants and purity of Ca-chelating agents evaluated using Ca-sensitive electrodes by the double-log optimization method Cell Calcium 15, 209-46.] cannot be applied to Mg2+ macroelectrodes. The pH titration method of Moisescu and Pusch (Pflügers, Arch., 355, R122, 1975) predicted EGTA purity and Ca2+ contamination, but Kapp values for EGTA were approximate. It cannot be applied to Mg2+ binding. The partition method [Godt, R.E., 1974. Calcium-activated tension of skinned muscle fibres of the frog. Dependence on magnesium adenosine triphosphate concentration J. Gen. Physiol. 63, 722-739.] only approximately estimated the K(app). Calibration, maintaining contaminating [Ca2+]/[Mg2+] at < 1micromol l(-1), and setting standards by dilution, is the ultimate check of calculated ionised concentrations, although technically difficult. The macroelectrode method of Lüthi et al. [1997. Calibration of Mg2+ -selective macromolecules down to 1 micromol l(-1) in intracellular and Ca+ - containing extracellular solutions. Exp. Physiol. 82, 453-467] accurately predicted purity and Kapp at pKapp values > 4 and was independent of electrode characteristics. It is considered the method of choice. Macroelectrode primary calibration should be carried out in solutions varying from 0.5 to 10 mmol l(-1) combined with either Ca-EGTA or Mg-EDTA buffers; the [Ca2+] and [Mg2+] in other buffer ligands can be measured in a secondary calibration. PMID:16887174

  15. 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)

  16. 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.

  17. Treatment of otitis externa associated with Corynebacterium kroppenstedtii in a peach-faced lovebird (Agapornis roseicollis) with an acetic and boric acid commercial solution.

    PubMed

    Martel, An; Haesebrouck, Freddy; Hellebuyck, Tom; Pasmans, Frank

    2009-06-01

    A 5-year-old lovebird (Agapornis roseicollis) was presented with scaly crusts around both external ear openings and exudate present around the left ear. The bird had been treated with ivermectin and enrofloxacin without success. A pure culture of Corynebacterium kroppenstedtii was isolated from both ears. After susceptibility testing, a treatment of an acetic and boric acid solution administered topically 3 times daily was prescribed. The scaly appearance disappeared after 14 days of treatment and C kroppenstedtii could not be reisolated. PMID:19673461

  18. 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. PMID:23223274

  19. Biomimetic apatite formation on calcium phosphate-coated titanium in Dulbecco's phosphate-buffered saline solution containing CaCl(2) with and without fibronectin.

    PubMed

    Chen, Cen; Lee, In-Seop; Zhang, Sheng-Min; Yang, Hyeong Cheol

    2010-06-01

    Calcium phosphate (CaP) thin films with different degrees of crystallinity were coated on the surfaces of commercially pure titanium by electron beam evaporation. The details of apatite nucleation and growth on the coating layer were investigated in Dulbecco's phosphate-buffered saline solutions containing calcium chloride (DPBS) or DPBS with fibronectin (DPBSF). The surfaces of the samples were examined by field emission scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The concentrations of fibronectin and calcium ions (Ca(2+)) were monitored by the bicinchoninic acid method (BCA) and use of a calcium assay kit (DICA-500), respectively. Apatite initially formed at the fastest rate on the CaP-coated samples with the lowest degree of crystallinity and reached the maximum Ca(2+) concentration after immersion in DPBS solution for 15min. After 15min the concentration of Ca(2+) decreased with the growth of apatite on the coating layers. For all the samples the maximum Ca(2+) concentration in the DPBS solutions decreased with increasing crystallinity and immersion time to reach the maximum concentration increased. The presence of fibronectin in the DPBS solutions delayed the formation and affected the morphology of the apatite. Fibronectin incorporated into apatite deposited on the surface of titanium did not affect its biological activity in terms of promoting osteoblast adhesion. PMID:19962459

  20. The role of pH and osmolarity in evoking the acetic acid-induced wiping response in a model of nociception in frogs.

    PubMed

    Hamamoto, D T; Forkey, M W; Davis, W L; Kajander, K C; Simone, D A

    2000-04-17

    Acetic acid applied to the hindlimb of a frog evokes a vigorous wiping of the exposed skin. The aim of this study was to determine if acetic acid evokes this wiping response by decreasing subepidermal pH. Because acetic acid is hyperosmolar, a second aim was to determine if the osmolarity of acetic acid contributed to evoking the wiping response. In behavioral experiments, different acids or acetic acid/sodium acetate buffers at different pHs were used to evoke the wiping response. In separate experiments, subepidermal pH was measured in vitro while these same solutions were applied to samples of skin from frogs. The wiping response evoked by acetic acid was associated with a decrease in subepidermal pH to a level that has been shown to activate nociceptors. Interestingly, formic, oxalic, sulfuric, and hydrochloric acid evoked the wiping response without decreasing subepidermal pH. The osmolarity of acetic acid contributed to evoking the wiping response because buffers at subthreshold pHs evoked the wiping response. Also, the osmolarity required to evoke the wiping response depended upon the pH of the buffer. Thus, acetic acid and the buffers at pH 2.97 and 4.67 could evoke the wiping response by decreasing subepidermal pH. In contrast, formic, oxalic, sulfuric, and hydrochloric acid, as well as the buffers at pH 5.17 and 5.67, evoked the wiping response through another mechanism, perhaps by increasing subepidermal osmolarity. These studies demonstrate that both pH and osmolarity may contribute to nociception produced by algesic chemicals and may be important in inflammatory pain. PMID:10799688

  1. Growth of thick La2Zr2O7 buffer layers for coated conductors by polymer-assisted chemical solution deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Zhao, Yong; Xia, Yudong; Guo, Chunsheng; Cheng, C. H.; Zhang, Yong; Zhang, Han

    2015-06-01

    La2Zr2O7 (LZO) epitaxial films have been deposited on LaAlO3 (LAO) (1 0 0) single-crystal surface and bi-axially textured NiW (2 0 0) alloy substrate by polymer-assisted chemical solution deposition, and afterwards studied with XRD, SEM and AFM approaches. Highly in-plane and out-of-plane oriented, dense, smooth, crack free and with a sufficient thickness (>240 nm) LZO buffer layers have been obtained on LAO (1 0 0) single-crystal surface; The films deposited on NiW (2 0 0) alloy substrate are also found with high degree in-plane and out-of-plane texturing, good density with pin-hole-free, micro-crack-free nature and a thickness of 300 nm. Highly epitaxial 500 nm thick YBa2Cu3O7-x (YBCO) thin film exhibits the self-field critical current density (Jc) reached 1.3 MA/cm2 at 77 K .These results demonstrate the LZO epi-films obtained with current techniques have potential to be a buffer layer for REBCO coated conductors.

  2. Solution Processing of Cadmium Sulfide Buffer Layer and Aluminum-Doped Zinc Oxide Window Layer for Thin Films Solar Cells

    NASA Astrophysics Data System (ADS)

    Alam, Mahboob; Islam, Mohammad; Achour, Amine; Hayat, Ansar; Ahsan, Bilal; Rasheed, Haroon; Salam, Shahzad; Mujahid, Mohammad

    2014-07-01

    Cadmium sulfide (CdS) and aluminum-doped zinc oxide (Al:ZnO) thin films are used as buffer layer and front window layer, respectively, in thin film solar cells. CdS and Al:ZnO thin films were produced using chemical bath deposition (CBD) and sol-gel technique, respectively. For CBD CdS, the effect of bath composition and temperature, dipping time and annealing temperature on film properties was investigated. The CdS films are found to be polycrystalline with metastable cubic crystal structure, dense, crack-free surface morphology and the crystallite size of either few nanometers or 12-17 nm depending on bath composition. In case of CdS films produced with 1:2 ratio of Cd and S precursors, spectrophotometer studies indicate quantum confinement effect, owing to extremely small crystallite size, with an increase in Eg value from 2.42 eV (for bulk CdS) to 3.76 eV along with a shift in the absorption edge toward 330 nm wavelength. The optimum annealing temperature is 400°C beyond which film properties deteriorate through S evaporation and CdO formation. On the other hand, Al:ZnO films prepared via spin coating of precursor sols containing 0.90-1.10 at.% Al show that, with an increase in Al concentration, the average grain size increases from 28 nm to 131 nm with an associated decrease in root-mean-square roughness. The minimum value of electrical resistivity, measured for the films prepared using 0.95 at.% Al in the precursor sol, is 2.7 × 10-4 Ω ṡ cm. The electrical resistivity value rises upon further increase in Al doping level due to introduction of lattice defects and Al segregation to the grain boundary area, thus limiting electron transport through it.

  3. 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.

  4. Influence of a polymeric solution buffer layer on the chemical bath deposition of polycrystalline PbS films

    NASA Astrophysics Data System (ADS)

    González-Alfaro, Y.; Fernández-Lima, F. A.; Larramendi, E. M.; Fonseca Filho, H. D.; da Costa, M. E. H. Maia; Freire, F. L., Jr.; Prioli, R.; de Avillez, R. R.; da Silveira, E. F.; Calzadilla, O.; de Melo, O.; Pedrero, E.; Hernández, E.

    2005-08-01

    Polycrystalline thin films of PbS grown on glass substrates previously coated with PbS colloidal particles in a polyvinyl alcohol solution were obtained by chemical bath deposition (CBD). The X-ray diffraction procedures showed evidence of polycrystalline films of cubic PbS with a preferred normal orientation of the planes [100] with the growth direction. The film texture showed a strong influence of the initial conditions of the surface. Moreover, changes in colour, morphology and grain size of the films were observed by optic and atomic force microscopy (AFM). Rutherford backscattering spectrometry (RBS) showed a dependence of the thickness and roughness of the PbS films with the growth initial conditions. A kinetic growth model is proposed to explain the changes in the structure and morphology of the PbS.

  5. Enhancement of inverted polymer solar cells with solution-processed ZnO-TiOX composite as cathode buffer layer

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Shao, Shuyan; Meng, Bin; Fang, Gang; Xie, Zhiyuan; Wang, Lixiang; Li, Xinglin

    2012-05-01

    Solution-processed zinc oxide (ZnO) nanocrystal modified with titanium oxide (TiOX) precursor is introduced as cathode interfacial layer in inverted bulk-heterojunction polymer solar cells. The resultant inverted polymer solar cell exhibits an open-circuit voltage of 0.87 V, a fill factor of 0.67, and an overall power conversion efficiency of 6.53%, respectively, higher than those of the control cells with sole ZnO or TiOX as the cathode interfacial layers. Further studies verify that the improved morphology and electronic structure of ZnO-TiOX composite layer favors reducing shunt loss and interfacial charge recombination and hence enhancing the photovoltaic performance.

  6. 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.

  7. 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}.

  8. Effect of different concentrations of acetic, citric, and propionic acid dipping solutions on bacterial contamination of raw chicken skin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial contamination of raw, processed poultry may include spoilage bacteria and foodborne pathogens. We evaluated different combinations of organic acid (OA) wash solutions for their ability to reduce bacterial contamination of raw chicken skin and to inhibit growth of spoilage bacteria and path...

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  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. PMID:21764065

  15. 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.

  16. Predicting Effects of Corrosion Erosion of High Strength Steel Pipelines Elbow on CO2-Acetic Acid (HAc) Solution

    NASA Astrophysics Data System (ADS)

    Asmara, Y. P.; Ismail, M. F.; Giok Chui, L.; Halimi, Jamiludin

    2016-02-01

    Simultaneously effect of erosion combined with corrosion becomes the most concern in oil and gas industries. It is due to the fast deterioration of metal as effects of solid particles mixed with corrosive environment. There are many corrosion software to investigate possible degradation mechanisms developed by researchers. They are using many combination factors of chemical reactions and physical process. However effects of CO2 and acid on pipelines orientations are still remain uncovered in their simulation. This research will investigate combination effects of CO2 and HAc on corrosion and erosion artificial environmental containing sands particles in 45°, 90° and 180° elbow pipelines. The research used theoretical calculations combined with experiments for verification. The main concerns are to investigate the maximum erosion corrosion rate and maximum shear stress at the surface. Methodology used to calculate corrosion rate are Linear Polarization Resistance (LPR) and weight loss. The results showed that at 45°, erosion rate is the more significant effects in contributing degradation of the metal. The effects of CO2 and HAc gave significant effects when flow rate of the solution are high which reflect synergism effects of solid particles and those chemical compositions.

  17. 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(M) . delta) > 2. A slightly higher value of solute rejection is found in Membrane-2. PMID:16499917

  18. 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. PMID:26264520

  19. 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 by comparing simulation results with true answers. Overall, ABSIS can accurately and efficiently estimate rare event probabilities for all examples, often with smaller variance than other importance sampling algorithms. The ABSIS method is general and can be applied to study rare events of other stochastic networks with complex probability landscape.

  20. 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 surface at the end of the dissolution experiment. HR-TEM showed that the crocidolite lattice structure, the fibrous habit and the high aspect ratio are preserved upon leaching, while Fe-bearing nanoparticles, likely amorphous and possibly displaced on top of the fibres, become clearly visible. As a conclusion, coating of the crocidolite fibres was demonstrated to occur due to precipitation of Fe-rich phases (both phosphates and oxide-hydroxides). The occurrence of such iron armouring may modulate asbestos toxicity and possibly be the initial step in the formation of asbestos ferruginous bodies.

  1. 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 the SB was derived as follows:k' = 3.9 {+-} 1.1 x 10{sup -8} exp(-1.3 {+-} 0.3 x 10{sup -3}{rho}),where k' is the rate constant at pH {approx} 9 in compacted purified SB of dry density ranging from 0.8 x 10{sup 3} to 1.2 x 10{sup 3} kg m{sup -3}.The rate constants of pyrite oxidation by DO in the compacted crude SB (0.8 x 10{sup 3} to 1.2 x 10{sup 3} kg m{sup -3}) were also calculated using the estimated De values of DO. In general, the values of rate constants in the crude SB are 1.5 times as large as that in the purified SB.

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Buffer Therapy for Cancer.

    PubMed

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

    2012-08-15

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

  9. 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

    NASA Astrophysics Data System (ADS)

    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.

  10. 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

  11. UV-ozone-treated MoO3 as the hole-collecting buffer layer for high-efficiency solution-processed SQ:PC71BM photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Yang, Qian-Qian; Yang, Dao-Bin; Zhao, Su-Ling; Huang, Yan; Xu, Zheng; Gong, Wei; Fan, Xing; Liu, Zhi-Fang; Huang, Qing-Yu; Xu, Xu-Rong

    2014-03-01

    The enhanced performance of a squaraine compound, with 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine as the donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor, in solution-processed organic photovoltaic devices is obtained by using UV-ozone-treated MoO3 as the hole-collecting buffer layer. The optimized thickness of the MoO3 layer is 8 nm, at which the device shows the best power conversion efficiency (PCE) among all devices, resulting from a balance of optical absorption and charge transport. After being treated by UV-ozone for 10 min, the transmittance of the MoO3 film is almost unchanged. Atomic force microscopy results show that the treated surface morphology is improved. A high PCE of 3.99% under AM 1.5 G illumination (100 mW/cm2) is obtained.

  12. Basal buffer systems for a newly glycosylated recombinant human interferon-? 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-? 1a (rhIFN-? 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 3.80.2. PMID:26215462

  13. Efficient Organic Photovoltaic Cells Using Hole-Transporting MoO3 Buffer Layers Converted from Solution-Processed MoS2 Films

    NASA Astrophysics Data System (ADS)

    Kato, Shogo; Ishikawa, Ryo; Kubo, Yosuke; Shirai, Hajime; Ueno, Keiji

    2011-07-01

    We introduce a new method to fabricate a MoO3 hole-transporting layer for organic photovoltaic cells (OPVs). We fabricated a MoS2 film from its solution and converted it to MoO3. MoS2 has a lamellar crystal structure similar to graphite, and it can be exfoliated into monolayer MoS2 dispersible in water. Li atoms were first intercalated into van der Waals gaps of MoS2, and the compound was immersed in water to generate H2 bubbles, which broke the van der Waals bond between adjacent MoS2 layers. The produced solution of MoS2 was spin-casted on an indium tin oxide substrate, and the film was oxidized by ozone. On the converted MoO3 hole-transporting layer, an organic photoconversion layer was fabricated by spin-casting a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM) composite solution. Fabricated OPVs revealed a power conversion efficiency as large as 3.14%, which was superior to that of P3HT/PCBM OPV with a poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole-transporting layer.

  14. Input buffering and back-pressure mechanism in ATM switches

    NASA Astrophysics Data System (ADS)

    Hashemi, Massoud R.; Leon-Garcia, Alberto

    1996-11-01

    VBR traffics with their bursty nature are still troublesome for ATM networks. The problem can be dealt with in call admission and bandwidth allocation stages and later, when the connection is established, by appropriate flow control schemes and buffer allocation mechanisms. Accommodating the large bursts in extra buffers at the inputs of switch fabric, during the overflow periods in the internal buffers, can be part of the solution given to this problem. Adding the input buffers is more preferable than expanding the internal memory because the input buffers are less expensive and can be used in bulk, while the internal buffers are more complex and expensive and not easily expandable. In this paper we consider a general model for switches with input buffers which consists of three parts: input buffer, I/O flow controller, and output (internal) buffer. In this way we isolate the switching mechanism and the back-pressure mechanism required in this kind of switches. We present different architectures for the I/O flow controller section and discuss the advantage and disadvantages of each model. We also address the QoS requirements of the individual connections in the input buffered switches by providing a specific architecture for the input buffer which unlike the traditional FIFO buffers allows scheduling the service among the cells in the input buffer without extra complexity.

  15. 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. PMID:23722276

  16. 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.

  17. Use of 1.0% or 0.5% KI-buffered Cathode Solution in ECC Ozonesondes: An Analysis of Dual-Ozonesonde Flights Over McMurdo Station, Antarctica Through Comparison With Remote Measurements and a Transfer Function to Convert Between Solution

    NASA Astrophysics Data System (ADS)

    Mercer, J. L.; Deshler, T.; Wood, S. W.; Nichol, S.

    2006-12-01

    Balloon-borne electrochemical concentration cell ozonesondes have been used to measure vertical profiles of ozone concentration from 0 to ~ 35km above McMurdo Station, Antarctica since 1986. These instruments have precisions of ~ 5%. The accuracy partially depends on the concentration of potassium- iodide (KI) cathode solution used in the electrochemical concentration cell. The use of 1.0% KI sensing solution has been maintained at McMurdo, even though in 1996 the manufacturer recommended reducing the concentration to 0.5%. Since then, laboratory studies (Smit et al., 2006) and field comparisons (Deshler et al., 2006) have indicated that the use of 1.0% KI cathode sensing solution can lead to an overestimation of ozone of up to 5% below 20 km, and up to 10% above 20 km. However, these overestimations are thought to be dependent on the amount of ozone entering the chamber, and thus could be less for measurements taken during times of polar ozone depletion. Here, we present the results of dual ozonesonde flights over McMurdo Station, Antarctica (78° S) using 1.0% and 0.5% buffered KI solution. Comparison between vertical ozone profiles from dual flights shows that 0.5% buffered solution consistently gives lower values of ozone than the 1.0% buffered solution when ozone partial pressure is > 5mPa. Total column ozone values are calculated from balloon flight measurements and compared with total column ozone measured by the Total Ozone Mapping Spectrometer (TOMS) on NASA's Earth Probe satellite and by a Dobson spectrophotometer operated approximately 1 km from McMurdo station. When total column ozone is > 250DU, the 0.5% solution compares better with the TOMS and Dobson spectrophotometer data. However, in most cases where total ozone is < 250DU, measurements with 1.0% solution compare better with both TOMS and Dobson spectrophotometer measurements. Recent analysis of dual-ozonesonde flights in mid- and polar latitudes has led to the development of a simple linear transfer function where the Ratio (1.0KI/0.5KI) = 1.106 - 0.027 × log10(Pressure). This transfer function has been suggested for homogenizing long-term data sets where both 1.0% and 0.5% KI-sensing solutions have been used, and thus its application is investigated here.

  18. 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. PMID:26572387

  19. 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.

  20. Cytosolic Ca2+ Buffers

    PubMed Central

    Schwaller, Beat

    2010-01-01

    “Ca2+ buffers,” a class of cytosolic Ca2+-binding proteins, act as modulators of short-lived intracellular Ca2+ signals; they affect both the temporal and spatial aspects of these transient increases in [Ca2+]i. Examples of Ca2+ buffers include parvalbumins (α and β isoforms), calbindin-D9k, calbindin-D28k, and calretinin. Besides their proven Ca2+ buffer function, some might additionally have Ca2+ sensor functions. Ca2+ buffers have to be viewed as one of the components implicated in the precise regulation of Ca2+ signaling and Ca2+ homeostasis. Each cell is equipped with proteins, including Ca2+ channels, transporters, and pumps that, together with the Ca2+ buffers, shape the intracellular Ca2+ signals. All of these molecules are not only functionally coupled, but their expression is likely to be regulated in a Ca2+-dependent manner to maintain normal Ca2+ signaling, even in the absence or malfunctioning of one of the components. PMID:20943758

  1. 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.

  2. The SVT Hit Buffer

    SciTech Connect

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

    1996-06-01

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

  3. Preparation of vinyl acetate

    DOEpatents

    Tustin, Gerald Charles (Kingsport, TN); Zoeller, Joseph Robert (Kingsport, TN); Depew, Leslie Sharon (Kingsport, TN)

    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.

  4. 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.

  5. [Acetate metabolism: experimental study].

    PubMed

    Girela, E; Hernández-Cueto, C; Calvo, M D; Luna, J D; Villanueva, E

    1993-06-01

    Plasma levels of ethanol and acetate, which is the end product of hepatic ethanol oxidation, have been studied in 60 rats. Animals were divided into two groups: 1) Control rats, and 2) Alcohol-treated rats. Ethanol and acetate were measured without any previous handling (endogenous levels) and after intraperitoneal injection of a single dose of ethanol. Blood specimens were taken at 30, 60, 120, 180 and 240 minutes after ethanol injection. Plasma levels of ethanol and acetate were performed by Head Space Gas Chromatography. Alcohol-treated animals had higher plasma acetate levels than control ones. There were statistically significant differences for acetate between both groups of rats at 0, 30, 120 and 180 minutes. PMID:8378582

  6. Mechanisms of retardation of rigid spherical particles with 3 to 1,085 nm radius in capillary electrophoresis, using buffered polyacrylamide (molecular weight 5 x 10(6)) solutions.

    PubMed

    Radko, S P; Chrambach, A

    1996-06-01

    Subjecting particles in the size range of 3 to 1085 nm radius (R) to capillary electrophoresis in buffered solution of entangled uncrosslinked polyacrylamide (M(r) 5 x 10(6)), it was found that particle size-dependent retardation ("molecular sieving") becomes electric field- and particle size range-dependent once the particle size exceeds 15-20 nm in radius. The field strength dependence of the retardation coefficient [KR = d(log mobility)/ d(polymer concentration] and the positive or negative sign of dKR/dR suggest the existence of two different mechanisms of molecular sieving depending on the particle size range: particles with diameters less than the screening length (or blob size) of the polymer network are thought to penetrate into the available spaces within a discontinuous polymer network; particles with diameters larger than the screening length (or blob size) of the polymer network are thought to undergo size-dependent retardation by exerting shear stress against polymer chains, and displacing them, so as to cause local deformations in a continuous polymer network. A limit in the separating capacity of molecular sieving, due to a sharp increase in the rate of band widening with polymer concentration, was found when the value of the retardation coefficient exceeded 60 (mL/g). PMID:8832177

  7. The Acetate Switch

    PubMed Central

    Wolfe, Alan J.

    2005-01-01

    To succeed, many cells must alternate between life-styles that permit rapid growth in the presence of abundant nutrients and ones that enhance survival in the absence of those nutrients. One such change in life-style, the “acetate switch,” occurs as cells deplete their environment of acetate-producing carbon sources and begin to rely on their ability to scavenge for acetate. This review explains why, when, and how cells excrete or dissimilate acetate. The central components of the “switch” (phosphotransacetylase [PTA], acetate kinase [ACK], and AMP-forming acetyl coenzyme A synthetase [AMP-ACS]) and the behavior of cells that lack these components are introduced. Acetyl phosphate (acetyl∼P), the high-energy intermediate of acetate dissimilation, is discussed, and conditions that influence its intracellular concentration are described. Evidence is provided that acetyl∼P influences cellular processes from organelle biogenesis to cell cycle regulation and from biofilm development to pathogenesis. The merits of each mechanism proposed to explain the interaction of acetyl∼P with two-component signal transduction pathways are addressed. A short list of enzymes that generate acetyl∼P by PTA-ACKA-independent mechanisms is introduced and discussed briefly. Attention is then directed to the mechanisms used by cells to “flip the switch,” the induction and activation of the acetate-scavenging AMP-ACS. First, evidence is presented that nucleoid proteins orchestrate a progression of distinct nucleoprotein complexes to ensure proper transcription of its gene. Next, the way in which cells regulate AMP-ACS activity through reversible acetylation is described. Finally, the “acetate switch” as it exists in selected eubacteria, archaea, and eukaryotes, including humans, is described. PMID:15755952

  8. Buffered Telemetry Demodulator

    NASA Technical Reports Server (NTRS)

    Tsou, Haiping; Hinedi, Sami M.; Shah, Biren; Lee, Robert

    1995-01-01

    Buffered telemetry demodulator (BTD) is radio receiver designed mainly for recovery of low-rate data binery phase-modulated onto square-wave subcarrier on sinusoidal or suppressed sinusoidal carrier signal and received at low symbol-to-noise ratio. In BTD, received signal not only processed in real time but also recorded and subsequently reprocessed to recover data otherwise lost. BTD could be implemented on general-purpose computer workstation.

  9. 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

  10. Chemiluminescence in activated human neutrophils: role of buffers and scavengers.

    PubMed

    Ginsburg, I; Misgav, R; Gibbs, D F; Varani, J; Kohen, R

    1993-06-01

    Human neutrophils (PMNs) suspended in Hanks' balanced salt solution (HBSS), which are stimulated either by polycation-opsonized streptococci or by phorbol myristate acetate (PMA), generate nonamplified (CL), luminol-dependent (LDCL), and lucigenin-dependent chemiluminescence (LUCDCL). Treatment of activated PMNs with azide yielded a very intense CL response, but only a small LDCL or LUCDCL responses, when horse radish peroxidase (HRP) was added. Both CL and LDCL depend on the generation of superoxide and on myeloperoxidase (MPO). Treatment of PMNs with azide followed either by dimethylthiourea (DMTU), deferoxamine, EDTA, or detapac generated very little CL upon addition of HRP, suggesting that CL is the result of the interaction among H2O2, a peroxidase, and trace metals. In a cell-free system practically no CL was generated when H2O2 was mixed with HRP in distilled water (DW). On the other hand significant CL was generated when either HBSS or RPMI media was employed. In both cases CL was markedly depressed either by deferoxamine or by EDTA, suggesting that these media might be contaminated by trace metals, which catalyzed a Fenton-driven reaction. Both HEPES and Tris buffers, when added to DW, failed to support significant HRP-induced CL. Nitrilotriacetate (NTA) chelates of Mn2+, Fe2+, Cu2+, and Co2+ very markedly enhanced CL induced by mixtures of H2O2 and HRP when distilled water was the supporting medium. Both HEPES and Tris buffer when added to DW strongly quenced NTA-metal-catalyzed CL. None of the NTA-metal chelates could boost CL generation by activated PMNs, because the salts in HBSS and RPMI interfered with the activity of the added metals. CL and LDCL of activated PMNs was enhanced by aminotriazole, but strongly inhibited by diphenylene iodonium (an inhibitor of NADPH oxidase) by azide, sodium cyanide (CN), cimetidine, histidine, benzoate, DMTU and moderately by superoxide dismutase (SOD) and by deferoxamine LUCDCL was markedly inhibited only by SOD but was boosted by CN. Taken together, it is suggested that CL generated by stimulated PMNs might be the result of the interactions among, NADPH oxidase, (inhibitable by diphenylene iodonium), MPO (inhibitable by sodium azide), H2O2 probably of intracellular origin (inhibitable by DMTU but not by catalase), and trace metals that contaminate salt solutions. The nature of the salt solutions employed to measure CL in activated PMNs is critical. PMID:8392491

  11. The quantitation of buffering action I. A formal & general approach

    PubMed Central

    Schmitt, Bernhard M

    2005-01-01

    Background Although "buffering" as a homeostatic mechanism is a universal phenomenon, the quantitation of buffering action remains controversial and problematic. Major shortcomings are: lack of a buffering strength unit for some buffering phenomena, multiple and mutually incommensurable units for others, and lack of a genuine ratio scale for buffering strength. Here, I present a concept of buffering that overcomes these shortcomings. Theory Briefly, when, for instance, some "free" H+ ions are added to a solution (e.g. in the form of strong acid), buffering is said to be present when not all H+ ions remain "free" (i.e., bound to H2O), but some become "bound" (i.e., bound to molecules other than H2O). The greater the number of H+ ions that become "bound" in this process, the greater the buffering action. This number can be expressed in two ways: 1) With respect to the number of total free ions added as "buffering coefficient b", defined in differential form as b = d(bound)/d(total). This measure expresses buffering action from nil to complete by a dimensionless number between 0 and 1, analogous to probabilites. 2) With respect to the complementary number of added ions that remain free as "buffering ratio B", defined as the differential B = d(bound)/d(free). The buffering ratio B provides an absolute ratio scale, where buffering action from nil to perfect corresponds to dimensionless numbers between 0 and infinity, and where equal differences of buffering action result in equal intervals on the scale. Formulated in purely mathematical, axiomatic form, the concept reveals striking overlap with the mathematical concept of probability. However, the concept also allows one to devise simple physical models capable of visualizing buffered systems and their behavior in an exact yet intuitive way. Conclusion These two measures of buffering action can be generalized easily to any arbitrary quantity that partitions into two compartments or states, and are thus suited to serve as standard units for buffering action. Some exemplary treatments of classical and non-classical buffering phenomena are presented in the accompanying paper. PMID:15769288

  12. 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.

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

    PubMed

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

    2016-12-01

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

  14. Effect of acetate on hypoglycemic seizures in mice.

    PubMed

    Urion, D; Vreman, H J; Weiner, M W

    1979-11-01

    In order to determine the effects of acetate on signs and symptoms of hypoglycemic seizures, Swiss Webster albino mice were injected intraperitoneally with solutions of NaCl, NaHCO3, NH4Cl, Na-acetate, or NH4-acetate, followed by subcutaneous injection of 7 U of insulin/kg body wt. Administration of Na- or NH4-acetate delayed and reduced the incidence of hypoglycemic reactions. Reinjection with Na-acetate or repeated injections with NH4-acetate caused a return to normal behavior patterns for 60 and 75%, respectively, of the affected hypoglycemic experimental animals. Injections of control animals with NaHCO3 or NH4Cl showed that the results were not due to alkalosis or acidosis. Acetate administration significantly increased plasma acetate and citrate, but not glucose, lactate, beta-hydroxybutyrate, or acetoacetate concentrations. The results indicate that intraperitoneal administration of acetate directly acted to prevent signs of hypoglycemia from occurring and reversed its manifestations when they were present. The protective effect of acetate suggests that it may serve as a fuel for the brain. PMID:488541

  15. 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.

  16. 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.

  17. 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-hydroxymuconic semialdehyde by the nonheme iron(II) metalloenzyme, homoprotocatechuate 2,3-dioxygenase. Several buffers were observed to engage in buffer/enzyme interactions within the active site pocket. These enzyme-buffer interactions were shown to inhibit substrate turnover and to contribute additional enthalpy terms to the overall heat of reaction observed for substrate turnover (and for substrate binding). PMID:26794358

  18. 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.

  19. 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.

  20. Irrigation with N,N-dichloro-2,2-dimethyltaurine (NVC-422) in a citrate buffer maintains urinary catheter patency in vitro and prevents encrustation by Proteus mirabilis.

    PubMed

    Rani, Suriani Abdul; Celeri, Chris; Najafi, Ron; Bley, Keith; Debabov, Dmitri

    2016-06-01

    Long-term use of indwelling urinary catheters can lead to urinary tract infections and loss of catheter patency due to encrustation and blockage. Encrustation of urinary catheters is due to formation of crystalline biofilms by urease-producing microorganisms such as Proteus mirabilis. An in vitro catheter biofilm model (CBM) was used to evaluate current methods for maintaining urinary catheter patency. We compared antimicrobial-coated urinary Foley catheters, with both available catheter irrigation solutions and investigational solutions containing NVC-422 (N,N-dichloro-2,2-dimethyltaurine; a novel broad-spectrum antimicrobial). Inoculation of the CBM reactor with 10(8) colony-forming units of P. mirabilis resulted in crystalline biofilm formation in catheters by 48 h and blockage of catheters within 5 days. Silver hydrogel or nitrofurazone-coated catheters did not extend the duration of catheter patency. Catheters irrigated daily with commercially available solutions such as 0.25 % acetic acid and isotonic saline blocked at the same rate as untreated catheters. Daily irrigations of catheters with 0.2 % NVC-422 in 10 mM acetate-buffered saline pH 4 or Renacidin maintained catheter patency throughout 10-day studies, but P. mirabilis colonization of the CBM remained. In contrast, 0.2 % NVC-422 in citrate buffer (6.6 % citric acid at pH 3.8) resulted in an irrigation solution that not only maintained catheter patency for 10 days but also completely eradicated the P. mirabilis biofilm within one treatment day. These data suggest that an irrigation solution containing the rapidly bactericidal antimicrobial NVC-422 in combination with citric acid to permeabilize crystalline biofilm may significantly enhance catheter patency versus other approved irrigation solutions and antimicrobial-coated catheters. PMID:26282899

  1. BUFFERS AND VEGETATIVE FILTER STRIPS

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Formation of acetic anhydride by carbonylation of methyl acetate

    SciTech Connect

    Mamyan, V.A.; Barsegyan, V.L.; Pirozhkov, S.D.; Sominskii, S.D.

    1986-04-01

    This paper studies the carbonylation reaction of methyl acetate (MA) with the formation of acetic anhydride, and also elucidates the mechanism of this reaction in the presence of a catalytic system including RhCl/sub 3/, Zn acetate, and MeI. The results obtained show that the metal halides studied can be arranged in order of activity and selectivity: RhCl/sub 3/ greater than RuCl/sub 3/ greater than PdCl/sub 2/. Small quantities of acetaldehyde, butyradehyde, acetic acid, and acetone are found in the reaction products.

  3. 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. PMID:26484390

  4. 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.

  5. [Nomegestrol acetate: clinical pharmacology].

    PubMed

    Lello, S

    2009-10-01

    Progestogens are used in clinical practice in some conditions. Their effects depend on their chemical structure, pharmacokinetics, pharmacodynamics, with important differences among various progestogens. Generally, progestins are classified according to their parent molecule, of which often they keep some features. Derivatives of 19-nor-progesterone are characterized by high selectivity of action on progestin receptor. In particular, nomegestrol acetate (NomAc) shows an important progestational potency, neutral gluco-lipid profile, and antigonadotropic activity. It is used for treating menstrual cycle disorders and for hormone replacement therapy in menopause in association with an estrogen. In future, thanks to its antigonadotropic activity, NomAc will be used in estroprogestin combinations in fertile women, thus taking advantage of its tolerability profile and obtaining numerous non-contraceptive benefits as well. PMID:19749678

  6. 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. .

  7. 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.

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

    PubMed

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

    2007-01-01

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

  9. 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 attention for robust systems science, and precision biomarkers that will stand the test of time. PMID:26669610

  10. Communal orientation may not buffer burnout.

    PubMed

    Truchot, D; Keirsebilck, L; Meyer, S

    2000-06-01

    Communal orientation (a desire to give and receive benefits in response to the needs of and out of concern for others) has had a buffer effect on burnout, in particular when the helping relationship is perceived by the helper as inequitable. This result, however, comes from research involving a specific professional group, medical personnel, that is, a group with a medical helping model wherein recipients are neither held responsible for their problem nor for the solution. We hypothesized that among professional helpers with a compensatory model wherein recipients are not held responsible for their problem but for the solution, and who perceive the relationship as inequitable, not only will a communal orientation not have effect on burnout, but it will reduce personal accomplishment. We present some results supporting this hypothesis. PMID:10876337

  11. 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. PMID:21576891

  12. 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. PMID:26790840

  13. Partner Buffering of Attachment Insecurity

    PubMed Central

    Simpson, Jeffry A.; Overall, Nickola C.

    2014-01-01

    Insecurely attached people have less happy, unstable romantic relationships, but the quality of their relationships should depend on how their partners regulate them. Some partners find ways to buffer (emotionally and behaviorally regulate) insecurely attached individuals, which makes them feel better, behave more constructively, and improves their relationships. Understanding when and how this important interpersonal process works requires a dyad-centered approach. In this article, we describe core tenets of attachment theory and the two forms of attachment insecurity (anxiety and avoidance). We then present the Dyadic Regulation Model of Insecurity Buffering, which explains how and why certain types of buffering behaviors soothe the worries and improve the relationship perceptions and behaviors of anxious or avoidant people. We next review studies of couples trying to resolve major conflicts that illustrate some ways in which partners can successfully buffer the insecure reactions of anxious and avoidant individuals. We conclude by discussing other traits and social contexts to which our model can be applied. PMID:25214722

  14. 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

  15. Antibiofilm Properties of Acetic Acid

    PubMed Central

    Bjarnsholt, Thomas; Alhede, Morten; Jensen, Peter Østrup; Nielsen, Anne K.; Johansen, Helle Krogh; Homøe, Preben; Høiby, Niels; Givskov, Michael; Kirketerp-Møller, Klaus

    2015-01-01

    Bacterial biofilms are known to be extremely tolerant toward antibiotics and other antimicrobial agents. These biofilms cause the persistence of chronic infections. Since antibiotics rarely resolve these infections, the only effective treatment of chronic infections is surgical removal of the infected implant, tissue, or organ and thereby the biofilm. Acetic acid is known for its antimicrobial effect on bacteria in general, but has never been thoroughly tested for its efficacy against bacterial biofilms. In this article, we describe complete eradication of both Gram-positive and Gram-negative biofilms using acetic acid both as a liquid and as a dry salt. In addition, we present our clinical experience of acetic acid treatment of chronic wounds. In conclusion, we here present the first comprehensive in vitro and in vivo testing of acetic acid against bacterial biofilms. PMID:26155378

  16. Sorption, uptake, and biotransformation of 17β-estradiol, 17α-ethinylestradiol, zeranol, and trenbolone acetate by hybrid poplar.

    PubMed

    Bircher, Sam; Card, Marcella L; Zhai, Guangshu; Chin, Yu-Ping; Schnoor, Jerald L

    2015-12-01

    Hormonally active compounds may move with agricultural runoff from fields with applied manure and biosolids into surface waters where they pose a threat to human and environmental health. Riparian zone plants could remove hormonally active compounds from agricultural runoff. Therefore, sorption to roots, uptake, translocation, and transformation of 3 estrogens (17β-estradiol, 17α-ethinylestradiol, and zeranol) and 1 androgen (trenbolone acetate) commonly found in animal manure or biosolids were assessed by hydroponically grown hybrid poplar, Populus deltoides x nigra, DN-34, widely used in riparian buffer strips. Results clearly showed that these hormones were rapidly removed from 2 mg L(-1) hydroponic solutions by more than 97% after 10 d of exposure to full poplar plants or live excised poplars (cut-stem, no leaves). Removals by sorption to dead poplar roots that had been autoclaved were significantly less, 71% to 84%. Major transformation products (estrone and estriol for estradiol; zearalanone for zeranol; and 17β-trenbolone from trenbolone acetate) were detected in the root tissues of all 3 poplar treatments. Root concentrations of metabolites peaked after 1 d to 5 d and then decreased in full and live excised poplars by further transformation. Metabolite concentrations were less in dead poplar treatments and only slowly increased without further transformation. Taken together, these findings show that poplars may be effective in controlling the movement of hormonally active compounds from agricultural fields and avoiding runoff to streams. PMID:26184466

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

    NASA Astrophysics Data System (ADS)

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

    2007-01-01

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

  18. 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.

  19. 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.

  20. 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. PMID:18648426

  1. Effects of L-cysteine and N-acetyl-L-cysteine on 4-hydroxy-2, 5-dimethyl-3(2H)-furanone (furaneol), 5-(hydroxymethyl)furfural, and 5-methylfurfural formation and browning in buffer solutions containing either rhamnose or glucose and arginine.

    PubMed

    Haleva-Toledo, E; Naim, M; Zehavi, U; Rouseff, R L

    1999-10-01

    Solutions of L-cysteine (Cys) and N-acetyl-L-cysteine (AcCys), containing glucose or rhamnose, with or without arginine, were buffered to pH 3, 5, and 7 and incubated at 70 degrees C for 48 h. Cys and AcCys inhibited the formation of (hydroxymethyl)furfural (HMF) from glucose and methylfurfural (MF) from rhamnose under acidic conditions. AcCys inhibited the accumulation of 4-hydroxy-2, 5-dimethyl- 3(2H)-furanone (DMHF, Furaneol) from rhamnose, but Cys, under our experimental conditions, enhanced Furaneol accumulation from rhamnose. Cys and AcCys reacted directly with Furaneol but not with HMF or MF. Both Cys and AcCys inhibited nonenzymatic browning at pH 7. At pH 3, however, Cys reacted with both glucose and rhamnose to produce unidentified compounds that increased the visible absorbency. PMID:10552780

  2. 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

  3. Microscopic optical buffering in a harmonic potential.

    PubMed

    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

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

    PubMed

    Trewby, William; Livesey, Duncan; Voïtchovsky, Kislon

    2016-02-23

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

  5. 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

    2010-04-01

    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. PMID:20449456

  6. 21 CFR 73.2396 - Lead acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Lead acetate. 73.2396 Section 73.2396 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a) Identity. The color additive lead acetate is the trihydrate of lead (2+) salt of acetic acid. The color additive has the chemical formula...

  7. 21 CFR 73.2396 - Lead acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Lead acetate. 73.2396 Section 73.2396 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a) Identity. The color additive lead acetate is the trihydrate of lead (2+) salt of acetic acid. The color additive has the chemical formula...

  8. 21 CFR 73.2396 - Lead acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Lead acetate. 73.2396 Section 73.2396 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a) Identity. The color additive lead acetate is the trihydrate of lead (2+) salt of acetic acid. The color additive has the chemical formula...

  9. 21 CFR 73.2396 - Lead acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Lead acetate. 73.2396 Section 73.2396 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a) Identity. The color additive lead acetate is the trihydrate of lead (2+) salt of acetic acid. The color additive has the chemical formula...

  10. 21 CFR 73.2396 - Lead acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Lead acetate. 73.2396 Section 73.2396 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a) Identity. The color additive lead acetate is the trihydrate of lead (2+) salt of acetic acid. The color additive has the chemical formula...

  11. 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. PMID:25377184

  12. 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

  13. 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)

  14. Buffer Layer R and D for YBCO Coated Conductor Composite Wires

    SciTech Connect

    Paranthaman, M. Parans; Sathyamurthy, S.; Aytug, T.; Leonard, K.J.; Goyal, A.; Zhai, H.Y.; Kroeger, D.M.; Christen, D.K.; Li, X.; Verebelyi, D.T.; Schoop, U.; Thieme, C.; Kodenkandath, T.; Zhang, W.; Rupich, M.W.; Ericson, R.E.

    2004-06-28

    Buffer layers play a key role in the YBa2Cu3O7-{delta} (YBCO) coated conductor composite wire technology. The important buffer layer characteristics are: these buffers should prevent metal diffusion into the superconductor from the substrate; possibly act as oxygen diffusion barriers; should be smooth, continuous, crack-free, highly aligned and dense. In order to develop low-cost alternative buffer layer architectures to the standard architecture of YBCO/CeO2/YSZ/Y2O3/Ni/Ni-W, LaMnO3 (LMO) and La2Zr2O7 (LZO) buffers were chosen for this study. These buffers were grown epitaxially on biaxially textured and strengthened Ni-W3% metal tapes by scalable vapor and/or solution techniques. LaMnO3 buffers were grown epitaxially on Ni-W substrates by rf sputtering, and La2Zr2O7 buffers were grown by a Metal-Organic Deposition (MOD). Detailed microstructural characterizations indicate that both of these buffers were excellent Ni diffusion barrier layers and high current YBCO films were grown on both LMO and LZO buffer templates.

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

    PubMed

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

    2012-01-01

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

  16. 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...

  17. 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.

  18. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium acetate. 184.1185 Section 184.1185 Food... Specific Substances Affirmed as GRAS § 184.1185 Calcium acetate. (a) Calcium acetate (Ca (C2H3O2)2, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid....

  19. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with... 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...

  20. 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...

  1. 12 CFR 324.11 - Capital conservation buffer and countercyclical capital buffer amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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

  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-based formulations, especially at protein concentrations up to and including 115 mg/mL. PMID:26455339

  3. Enhancement of the wet properties of transparent chitosan-acetic-acid-salt films using microfibrillated cellulose.

    PubMed

    Nordqvist, David; Idermark, Johan; Hedenqvist, Mikael S; Gällstedt, Mikael; Ankerfors, Mikael; Lindström, Tom

    2007-08-01

    This report presents a new route to enhance the wet properties of chitosan-acetic-acid-salt films using microfibrillated cellulose (MFC). The enhancement makes it easier to form chitosan-acetic-acid-salt films into various shapes at room temperature in the wet state. Chitosan with MFC was compared with the well-known buffer treatment. It was observed that films containing 5 wt % MFC were visually identical to the buffered/unbuffered films without MFC. Field-emission scanning electron microscopy indicated that MFC formed a network with uniformly distributed fibrils and fibril bundles in the chitosan matrix. The addition of MFC reduced the risk of creases and deformation in the wet state because of a greater wet stiffness. The wet films containing MFC were also extensible. Although the stiffness, strength and extensibility were highest for the buffered films, the wet strength of the MFC-containing unbuffered films was sufficient for wet forming operations. The effects of MFC on the mechanical properties of the dry chitosan films were small or absent. It was concluded that the addition of MFC is an acceptable alternative to buffering for shaping chitosan films/products in the wet state. The advantages are that the "extra" processing step associated with buffering is unnecessary and that the film matrix remains more water-soluble. PMID:17645308

  4. Buffered Communication Analysis in Distributed Multiparty Sessions

    NASA Astrophysics Data System (ADS)

    Deniélou, Pierre-Malo; Yoshida, Nobuko

    Many communication-centred systems today rely on asynchronous messaging among distributed peers to make efficient use of parallel execution and resource access. With such asynchrony, the communication buffers can happen to grow inconsiderately over time. This paper proposes a static verification methodology based on multiparty session types which can efficiently compute the upper bounds on buffer sizes. Our analysis relies on a uniform causality audit of the entire collaboration pattern - an examination that is not always possible from each end-point type. We extend this method to design algorithms that allocate communication channels in order to optimise the memory requirements of session executions. From these analyses, we propose two refinements methods which respect buffer bounds: a global protocol refinement that automatically inserts confirmation messages to guarantee stipulated buffer sizes and a local protocol refinement to optimise asynchronous messaging without buffer overflow. Finally our work is applied to overcome a buffer overflow problem of the multi-buffering algorithm.

  5. New findings about the lipase acetylation of nanofibrillated cellulose using acetic anhydride as acyl donor.

    PubMed

    Božič, Mojca; Vivod, Vera; Kavčič, Sabina; Leitgeb, Maja; Kokol, Vanja

    2015-07-10

    The acetylation efficiency of nanofibrillated cellulose (NFC) with acetic anhydride as acetyl donor was studied using lipase from Aspergillus niger in a mixture of dimethyl sulphoxide (DMSO) and phosphate buffer solution at ambient conditions and in supercritical carbon dioxide (scCO2). The chemical acetylation of NFC with comparable ester content was carried out for comparison. The ATR-FTIR, solid-state CP/MAS (13)C NMR and DSC analyses revealed that, besides the enzyme-catalysed acetylation, predominantly appearing at the C-6 position of cellulose hydroxyls, a strong and stable acyl-enzyme intermediate attachment also occurred on the NFC via Maillard reaction. Enzymatic acetylation via attached acyl-enzyme complex on NFC yielded high hydophobicity (contact angle of 84±9°), whereas the chemical acetylation with comparable ester content resulted in a much lower hydrophobic surface with a contact angle of 33±3°. Finally, the adsorption capacity profiles of lysozyme and BSA proteins on native, chemically and enzymatically acetylated NFC as a function of the pH medium were determined. PMID:25857991

  6. 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. PMID:26851357

  7. 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.

  8. 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.

  9. Influence of acetate and CO2 on the TMAO-reduction reaction by Shewanella baltica.

    PubMed

    Debevere, J; Devlieghere, F; van Sprundel, P; De Meulenaer, B

    2001-08-15

    In this work, the TMAO-reduction by Shewanella baltica, one of the representative spoilage organisms in modified atmosphere packaged marine fish fillets, and the effect of acetate and CO2 on this reduction were studied in vitro. The growth of S. baltica and the corresponding evolution of some compounds (acetate, lactate, pyruvate, glucose and trimethylamine (TMA)) were followed during storage at 4 degrees C in two types of broths. The first medium was a defined medium (pH = 6.8) to which lactate or pyruvate was added as hydrogen donor. Pyruvate showed to be more efficient as H-donor for S. baltica than lactate, as growth was much faster when equimolar amounts of pyruvate instead of lactate were present. Although the growth of S. baltica, when pyruvate is used as H-donor and no acetate is added, was not much inhibited by the CO2-atmosphere, CO2 had a pronounced effect on the studied reactions as it partly inhibited the reduction of pyruvate to acetate. The effect of acetate on this reaction was, on the other hand, not significant. To simulate the reactions occurring in situ, a buffered fish extract (pH = 6.8) was used. In spite of the neutral pH, the growth of S. baltica in this medium was highly inhibited by relatively small concentrations of acetate (< 0.3%). When 0.1% of acetate was added to the fish extract, less acetate was formed and lactate was more slowly consumed in comparison to the experiments without the addition of acetate. The consumption of lactate and the production of acetate were almost completely inhibited when the fish extract contained 0.25% of acetate. Apparently, the addition of acetate inhibited the use of lactate as H-donor. After extended storage times (17 days at 4 degrees C) TMA production started. Most probably, alternative H-donors were used by S. baltica, from which the pathway seems to be less energy efficient. This can be deduced from the exceptional growth inhibition of S. baltica by small amounts of acetate. However, when practical storage times for fish (e.g. 6 days at 4 degrees C after packaging) are considered, growth and TMAO-reduction by S. baltica was completely inhibited during this period by 0.25% of acetate. PMID:11545211

  10. Chromatographic transport of alkaline buffers through reservoir rock

    SciTech Connect

    Jensen, J.A.; Radke, C.J.

    1985-09-01

    Use of relatively low-pH alkaline buffers, such as sodium carbonate or sodium silicate, is explored as a means for overcoming sodium/hydrogen ion-exchange delay in alkaline waterflooding. A local equilibrium chromatographic model is outlined to describe the concentration velocities for injection of alkaline buffers into a linear porous medium which exhibits reversible sodium/hydrogen exchange. The theory predicts a buffer ion-exchange wave which is indeed substantially faster than that for equivalent-pH sodium hydroxide solutions. New experimental displacement data are presented for NaOH over a pH range from 11 to 13 and for 0.1, 0.5, and 1.0 w/o Na2CO3 flowing through a 1 w/o NaCl brine saturated Berea sandstone core at 50C. To permit a complete description of the system, column effluent concentrations are measured for sodium ions, hydroxide ions, THOH-tagged water, and UC-tagged carbonate. The experiments confirm that Na2CO3 propagates through the Berea sand at a higher rate than NaOH. For example, at pH = 11.4 Na2CO3 migrates with a velocity that is 3.5 times faster than NaOH. Comparison of experiment with the ion-exchange chromatography theory shows good agreement. We successfully model the concentration histories of tritium-labelled water, total carbon, sodium, and hydroxide, all with no adjustable parameters. This work establishes with both theory and experiment that buffered alkali significantly increases the propagation speed of hydroxide in reservoir sands in comparison with unbuffered alkali at equivalent sodium and hydroxide concentrations. Since lower pH buffered alkali can also protect against rock dissolution loss, the validated reduction of buffer ion-exchange lag considerably improves the promise of the alkaline-flooding process for field application. 29 refs., 11 figs., 1 tab.

  11. Inhibition of Ice Growth and Recrystallization by Zirconium Acetate and Zirconium Acetate Hydroxide

    PubMed Central

    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. PMID:23555701

  12. DNA-histidine complex formation in isoelectric histidine buffers.

    PubMed

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

    1999-04-01

    The free solution electrophoretic mobility of two DNA molecules of different molecular masses, 18 base pairs and 2686 base pairs, has been measured in isoelectric histidine buffers with and without added low-molecular-mass electrolytes. Extensive DNA-histidine complex formation is observed in isoelectric histidine buffer, as evidenced by distortion and splitting of the peaks in the electropherograms. Peak distortion and splitting can be decreased or eliminated by adding low-molecular-mass neutral salts to the solution, suggesting that the DNA-histidine complexes are stabilized by electrostatic interactions. The ability of various neutral salts to disrupt the DNA-histidine complexes depends on the molecular mass of the DNA and the concentration and type of added salt. PMID:10327637

  13. Phytogenic biosynthesis and emission of methyl acetate.

    PubMed

    Jardine, Kolby; Wegener, Frederik; Abrell, Leif; van Haren, Joost; Werner, Christiane

    2014-02-01

    Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic (13) C-pulse chasing to track the fate of C1-3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2 . (13) C-labelling of MA and CO2 branch emissions respond within minutes to changes in (13) C-positionally labelled pyruvate solutions fed through the transpiration stream. Strong (13) C-labelling of MA emissions occurred only under pyruvate-2-(13) C and pyruvate-2,3-(13) C feeding, but not pyruvate-1-(13) C feeding. In contrast, strong (13) CO2 emissions were only observed under pyruvate-1-(13) C feeding. These results demonstrate that MA (and other volatile and non-volatile metabolites) derive from the C2,3 atoms of pyruvate while the C1 atom undergoes decarboxylation. The latter is a non-mitochondrial source of CO2 in the light generally not considered in studies of CO2 sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO2 to the atmosphere. PMID:23862653

  14. Treatment of traumatic myositis ossificans with acetic acid iontophoresis.

    PubMed

    Wieder, D L

    1992-02-01

    The purpose of this case report is to document the treatment of a patient who had traumatic myositis ossificans with acetic acid iontophoresis. A 16-year-old boy developed quadriceps femoris muscle myositis ossificans as a result of a springboard diving accident. A 2% acetic acid solution was administered via iontophoresis into the myositis ossificans, followed by 8 minutes of pulsed ultrasound at 1.5 W/cm2. The treatment was performed three times per week for 3 weeks. At the conclusion of the treatments, radiographic findings indicated a 98.9% decrease in the size of the ossified mass. The patient regained full range of motion and was able to return to pain-free activity. This case report demonstrates the potential for a therapeutic program of acetic acid iontophoresis and ultrasound in eliminating myositis ossificans. PMID:1549634

  15. Reaction of nerve agents with phosphate buffer at pH 7.

    PubMed

    Creasy, William R; Fry, Roderick A; McGarvey, David J

    2012-07-12

    Chemical weapon nerve agents, including isopropyl methylphosphonofluoridate (GB or Sarin), pinacolyl methylphosphonofluoridate (GD or Soman), and S-(2-diisopropylaminoethyl) O-ethyl methylphosphonothioate (VX), are slow to react in aqueous solutions at midrange pH levels. The nerve agent reactivity increases in phosphate buffer at pH 7, relative to distilled water or acetate buffer. Reactions were studied using (31)P NMR. Phosphate causes faster reaction to the corresponding alkyl methylphosphonic acids, and produces a mixed phosphate/phosphonate compound as an intermediate reaction product. GB has the fastest reaction rate, with a bimolecular rate constant of 4.6 × 10(-3) M(-1)s(-1)[PO(4)(3-)]. The molar product branching ratio of GB acid to the pyro product (isopropyl methylphosphonate phosphate anhydride) is 1:1.4, independent of phosphate concentration, and the pyro product continues to react much slower to form GB acid. The pyro product has two doublets in the (31)P NMR spectrum. The rate of reaction for GD is slower than GB, with a rate constant of 1.26 × 10(-3) M(-1)s(-1) [PO(4)(3-)]. The rate for VX is considerably slower, with a rate constant of 1.39 × 10(-5) M(-1)s(-1) [PO(4)(3-)], about 2 orders of magnitude slower than the rate for GD. The rate constant of the reaction of GD with pyrophosphate at pH 8 is 2.04 × 10(-3) min(-1) at a concentration of 0.0145 M. The rate of reaction for diisopropyl fluorophosphate is 2.84 × 10(-3) min(-1) at a concentration of 0.153 M phosphate, a factor of 4 slower than GD and a factor of 15 slower than GB, and there is no detectable pyro product. The half-lives of secondary reaction of the GB pyro product in 0.153 and 0.046 M solution of phosphate are 23.8 and 28.0 h, respectively, which indicates little or no dependence on phosphate. PMID:22667763

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

    SciTech Connect

    Sheikh, S.; Ganesan, R.

    1996-12-31

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

  17. 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

  18. Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli

    PubMed Central

    Kirkpatrick, Christopher; Maurer, Lisa M.; Oyelakin, Nikki E.; Yoncheva, Yuliya N.; Maurer, Russell; Slonczewski, Joan L.

    2001-01-01

    Acetate and formate are major fermentation products of Escherichia coli. Below pH 7, the balance shifts to lactate; an oversupply of acetate or formate retards growth. E. coli W3110 was grown with aeration in potassium-modified Luria broth buffered at pH 6.7 in the presence or absence of added acetate or formate, and the protein profiles were compared by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Acetate increased the steady-state expression levels of 37 proteins, including periplasmic transporters for amino acids and peptides (ArtI, FliY, OppA, and ProX), metabolic enzymes (YfiD and GatY), the RpoS growth phase regulon, and the autoinducer synthesis protein LuxS. Acetate repressed 17 proteins, among them phosphotransferase (Pta). An ackA-pta deletion, which nearly eliminates interconversion between acetate and acetyl-coenzyme A (acetyl-CoA), led to elevated basal levels of 16 of the acetate-inducible proteins, including the RpoS regulon. Consistent with RpoS activation, the ackA-pta strain also showed constitutive extreme-acid resistance. Formate, however, repressed 10 of the acetate-inducible proteins, including the RpoS regulon. Ten of the proteins with elevated basal levels in the ackA-pta strain were repressed by growth of the mutant with formate; thus, the formate response took precedence over the loss of the ackA-pta pathway. The similar effects of exogenous acetate and the ackA-pta deletion, and the opposite effect of formate, could have several causes; one possibility is that the excess buildup of acetyl-CoA upregulates stress proteins but excess formate depletes acetyl-CoA and downregulates these proteins. PMID:11591692

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. All-optical buffering for DPSK packets

    NASA Astrophysics Data System (ADS)

    Liu, Guodong; Wu, Chongqing; Liu, Lanlan; Wang, Fu; Mao, Yaya; Sun, Zhenchao

    2013-12-01

    Advanced modulation formats, such as DPSK, DQPSK, QAM, have become the mainstream technologies in the optical network over 40Gb/s, the DPSK format is the fundamental of all advanced modulation formats. Optical buffers, as a key element for temporarily storing packets in order to synchronization or contention resolution in optical nodes, must be adapted to this new requirement. Different from other current buffers to store the NRZ or RZ format, an all-optical buffer of storing DPSK packets based on nonlinear polarization rotation in SOA is proposed and demonstrated. In this buffer, a section of PMF is used as fiber delay line to maintain the polarization states unchanged, the driver current of SOA is optimized, and no amplifier is required in the fiber loop. A packet delay resolution of 400ns is obtained and storage for tens rounds is demonstrated without significant signal degradation. Using proposed the new tunable DPSK demodulator, bit error rate has been measured after buffering for tens rounds for 10Gb/s data payload. Configurations for First-in First-out (FIFO) buffer or First-in Last-out (FILO) buffer are proposed based on this buffer. The buffer is easy control and suitable for integration. The terminal contention caused by different clients can be mitigated by managing packets delays in future all-optical network, such as optical packet switching network and WDM switching network.

  4. A Brownian model for multiclass queueing networks with finite buffers

    NASA Astrophysics Data System (ADS)

    Dai, Wanyang

    2002-07-01

    This paper is concerned with the heavy traffic behavior of a type of multiclass queueing networks with finite buffers. The network consists of d single server stations and is populated by K classes of customers. Each station has a finite capacity waiting buffer and operates under first-in first-out (FIFO) service discipline. The network is assumed to have a feedforward routing structure under a blocking scheme. A server stops working when the downstream buffer is full. The focus of this paper is on the Brownian model formulation. More specifically, the approximating Brownian model for the networks is proposed via the method of showing a pseudo-heavy-traffic limit theorem which states that the limit process is a reflecting Brownian motion (RBM) if the properly normalized d-dimensional workload process converges in distribution to a continuous process. Numerical algorithm with finite element method has been designed to effectively compute the solution of the Brownian model (W. Dai, Ph.D. thesis (1996); X. Shen et al. The finite element method for computing the stationary distribution of an SRBM in a hypercube with applications to finite buffer queueing networks, under revision for Queueing Systems).

  5. 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, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1005 Acetic acid. (a) Product. Acetic acid....

  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, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1005 Acetic acid. (a) Product. Acetic acid....

  7. 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...

  8. 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...

  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. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 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...

  12. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 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...

  13. 21 CFR 522.2476 - Trenbolone acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 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...

  14. 21 CFR 582.6185 - Calcium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium acetate. 582.6185 Section 582.6185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium acetate. (a) Product. Calcium acetate. (b) Conditions of use. This substance is...

  15. 21 CFR 582.6185 - Calcium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium acetate. 582.6185 Section 582.6185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium acetate. (a) Product. Calcium acetate. (b) Conditions of use. This substance is...

  16. 21 CFR 582.6185 - Calcium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium acetate. 582.6185 Section 582.6185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium acetate. (a) Product. Calcium acetate. (b) Conditions of use. This substance is...

  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 Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS § 184.1721 Sodium acetate. (a) Sodium acetate...

  18. 21 CFR 582.6185 - Calcium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium acetate. 582.6185 Section 582.6185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium acetate. (a) Product. Calcium acetate. (b) Conditions of use. This substance is...

  19. 21 CFR 582.6185 - Calcium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium acetate. 582.6185 Section 582.6185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 2 § 582.6185 Calcium acetate. (a) Product. Calcium acetate....

  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, 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...

  2. 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...

  3. 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...

  4. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with... C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  5. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with... C2H3O2Na·3H2O, CAS Reg. No. 6131-90-4) is the sodium salt of acetic acid and occurs naturally in plant...

  6. 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...

  7. The capacity of peatland buffer areas to retain inorganic nitrogen

    NASA Astrophysics Data System (ADS)

    Vikman, Anu; Sarkkola, Sakari; Nousiainen, Hannu; Kaila, Annu; Nieminen, Mika

    2010-05-01

    Natural and restored peatland buffer areas have proven to be effective constructions in reducing element transport such as nitrogen (N), phosphorus (P) and suspended solids from forested catchments (Nieminen et al. 2005, Väänänen et al. 2008) . In this study, nitrogen retention capacities of six peatland buffer areas were studied by adding ammonium nitrate (NH4NO3-N) solution into the inflow waters once (one area) or twice (five areas). The first addition was made in 2003, 2004 or 2005 and the second in 2008 and the duration of each addition event lasted for four days. The buffer areas were either undrained mires or drained peatlands rewetted 4-7 years before the present study and they covered an area of 0.1 - 4.9% of the catchment area upstream. Samples of the inflow and outflow waters were collected between 2002 and 2009, before and after the two additions. Samples of soil water, vegetation, peat and N2O were collected during 2007-2009. The emissions of N2O were measured using the closed chamber technique six to seven times before the N addition in 2008 and eight to nine times after it. The sampling was introduced from eight sampling plots at each buffer area. The biomass of above-ground and below-ground parts of plants was harvested from each of the study sites at peak standing crop in August of 2007 and 2008; before and after the second N addition. The samples were collected from 17-20 plots that were placed systematically to cover each buffer area as a grid. The below-ground parts of biomass were collected simultaneously with the above-ground biomass from the same plots. Peat monoliths (3×4×15 cm) down to a depth of 15 cm were sampled and divided into two layers of 7.5 cm thickness. Except for the first N addition in one area, the three largest buffer areas (relative size higher than 1%) retained the added inorganic N almost completely; their retention efficiencies during the year of addition were higher than 93% for both NO3-N and NH4-N. Two of the three smallest buffers (relative size lower than 0.25%) were still able to reduce inorganic N from the through-flow waters effectively, as their retention capacities for inorganic nitrogen varied between 58 and 89%. However, one small buffer area had a retention capacity of less than 20%. The factors contributing to efficient N retention were hydrological load during N addition, relative size of the buffer area, and the length of the buffer area, i.e. the distance between the inflow and outflow points. The buffer areas appeared to be efficient and long-term sinks for inorganic nitrogen, because the release of N during the 2-4 years after N addition was minor. The N2O emissions correlated significantly with the water table level and the concentrations of NO3-N and NH4-N in the soil water. Thus, in buffer areas with a high water table level the concentrations of NO3-N in the soil water and the emissions of N2O increased soon after the N addition had started. The total N loss as N2O was also larger than in areas where the water table level was lower and the concentrations of NO3-N in the soil water remained low. Compared with the high amount of N applied in the buffer areas, the loss of N as N2O was low from all buffer areas. The N content in the vegetation increased by about 6-43 kg (9-67 kg ha-1) at four of the five buffer areas, while a decrease in N content of about -2 kg was observed at one buffer area. The proportional retention in the vegetation was about 11-83% of the added N, except for the one buffer area. We suggest that a significant proportion of the N added has also been retained in microbial biomass and in the peat matrix. References Nieminen, M., E. Ahti, H. Nousiainen, S. Joensuu & M. Vuollekoski, 2005. Capacity of riparian buffer zones to reduce sediment concentrations in discharge from peatlands drained for forestry. Silva Fennica 39: 331-339. Väänänen, R., M. Nieminen, M. Vuollekoski, H. Nousiainen, T. Sallantaus, E-S. Tuittila & H. Ilvesniemi, 2008. Retention of phosphorus in peatland buffer zones at six forested catchments in southern Finland. Silva Fennica 42: 211-231.

  8. Transports of acetate and haloacetate in Burkholderia species MBA4 are operated by distinct systems

    PubMed Central

    2012-01-01

    Background Acetate is a commonly used substrate for biosynthesis while monochloroacetate is a structurally similar compound but toxic and inhibits cell metabolism by blocking the citric acid cycle. In Burkholderia species MBA4 haloacetate was utilized as a carbon and energy source for growth. The degradation of haloacid was mediated by the production of an inducible dehalogenase. Recent studies have identified the presence of a concomitantly induced haloacetate-uptake activity in MBA4. This uptake activity has also been found to transport acetate. Since acetate transporters are commonly found in bacteria it is likely that haloacetate was transported by such a system in MBA4. Results The haloacetate-uptake activity of MBA4 was found to be induced by monochloroacetate (MCA) and monobromoacetate (MBA). While the acetate-uptake activity was also induced by MCA and MBA, other alkanoates: acetate, propionate and 2-monochloropropionate (2MCPA) were also inducers. Competing solute analysis showed that acetate and propionate interrupted the acetate- and MCA- induced acetate-uptake activities. While MCA, MBA, 2MCPA, and butyrate have no effect on acetate uptake they could significantly quenched the MCA-induced MCA-uptake activity. Transmembrane electrochemical potential was shown to be a driving force for both acetate- and MCA- transport systems. Conclusions Here we showed that acetate- and MCA- uptake in Burkholderia species MBA4 are two transport systems that have different induction patterns and substrate specificities. It is envisaged that the shapes and the three dimensional structures of the solutes determine their recognition or exclusion by the two transport systems. PMID:23167477

  9. 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.

  10. Investigation on the Morphology of Precipitated Chemicals from te Buffer on Solid Substrates

    NASA Astrophysics Data System (ADS)

    Wang, Huabin; Zhang, Lijuan; Zhang, Feng; An, Hongjie; Chen, Shimou; Li, Hai; Wang, Peng; Wang, Xinyang; Wang, Yang; Yang, Haijun

    Buffer is often involved in the biological studies on a surface with the scanning probe microscopy and the remnant of the salts of buffer may affect the correct interpretation of the experimental results. However, the knowledge on the performance of chemicals of buffer on a substrate is still very poor. TE solution (Tris-HCl, NaCl, and ethylene diamine tetraacetic acid (EDTA)) is a widely used buffer in stocking biological molecules. Herein, we report the performance of the precipitated chemicals from TE solution on two typical substrates with several commonly used sample preparation methods. The results showed that the chemicals in TE solution could self-organize into parallel nanofilaments on hydrophobic highly oriented pyrolitic graphite (HOPG) surface by blotting the shortly incubated solution droplet from the substrate or by drying the diluted solution droplet naturally. In contrast, no such special structures were observed on hydrophilic mica using the same methods. By imaging in TE solutions, no special structures were found on either the HOPG or the mica. Moreover, the effects of the concentration of chemicals of TE buffer on the morphology of precipitated chemicals were also investigated.

  11. Cationic surfactant as a sensitizer for the spectrophotometric determination of hydrogen sulphide in air and evaluation of a new absorbing medium containing triethanolamine-zinc acetate-sodium hydroxide.

    PubMed

    Pandurangappa, M; Balasubramanian, N

    1996-01-01

    An extractive spectrophotometric method for the determination of trace amounts of hydrogen sulphide after fixing the gas in triethanolamine (TEA)-zinc acetate-sodium hydroxide solution is described. The method is based on the reaction of iodate with hydrogen sulphide in the presence of acid and excess chloride ion leading to the formation of ICl2- species which is used to iodinate 2',7'-dichlorofluorescein to form 2',7'-dichloro-4',5'-diiodofluorescein. The iodinated product formed is extracted into an organic solvent and sensitized by equilibrating with a cationic surfactant, cetrimide, in the presence of acetate buffer (pH 5.9 +/- 0.1). The colour system obeys Beer's law over the range 0-1 microg of hydrogen sulphide and the relative standard deviation is 2.4% for 10 determinations at 0.75 microg of hydrogen sulphide. The effect of interfering gases on the determination is discussed. The proposed absorbing solution has been evaluated using a hydrogen sulphide permeation device. This absorbing solution has an absorption efficiency of > 93% at a flow rate of 1.5 litre min(-1) for a sampling period of 2 h. The fixed H2S is stable for 40 days. The method has been applied to determine residual H2S levels in a laboratory fume hood and in the vicinity of sewage pumping station. The method can be used to determine as little as 0.05 microg of hydrogen sulphide. PMID:15093484

  12. 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...

  13. 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...

  14. 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...

  15. Pain perception following subcutaneous injections of citrate-buffered and phosphate-buffered epoetin alpha.

    PubMed

    Yu, A W; Leung, C B; Li, P K; Lui, S F; Lai, K N

    1998-06-01

    Subcutaneous injection of citrate-buffered epoetin alpha (EPO-alpha) causes pain. Substitution of citrate buffer with a phosphate buffer in the EPO-alpha resulted in a significant reduction in duration and severity of pain. It is possible that sodium citrate which is present in the EPO-alpha may be the agent that causes discomfort in the patients. PMID:9714028

  16. UNDERSTANDING, DERIVING, AND COMPUTING BUFFER CAPACITY

    EPA Science Inventory

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

  17. Supramolecular buffering by ring-chain competition.

    PubMed

    Paffen, Tim F E; Ercolani, Gianfranco; de Greef, Tom F A; Meijer, E W

    2015-02-01

    Recently, we reported an organocatalytic system in which buffering of the molecular catalyst by supramolecular interactions results in a robust system displaying concentration-independent catalytic activity. Here, we demonstrate the design principles of the supramolecular buffering by ring-chain competition using a combined experimental and theoretical approach. Our analysis shows that supramolecular buffering of a molecule is caused by its participation as a chain stopper in supramolecular ring-chain equilibria, and we reveal here the influence of various thermodynamic parameters. Model predictions based on independently measured equilibrium constants corroborate experimental data of several molecular systems in which buffering occurs via competition between cyclization, growth of linear chains, and end-capping by the chain-stopper. Our analysis reveals that the effective molarity is the critical parameter in optimizing the broadness of the concentration regime in which supramolecular ring-chain buffering occurs as well as the maximum concentration of the buffered molecule. To conclude, a side-by-side comparison of supramolecular ring-chain buffering, pH buffering, and molecular titration is presented. PMID:25581227

  18. 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.

  19. 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…

  20. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  1. 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.

  2. 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...

  3. 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...

  4. 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...

  5. 46 CFR 58.25-45 - Buffers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

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

  6. The buffer capacity of airway epithelial secretions

    PubMed Central

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

    2014-01-01

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

  7. 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...

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

    PubMed

    Lin, Ya-Ting; Liang, Chenju

    2015-10-01

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

  9. Influence of Ammonium Acetate Concentration on Receptor-Ligand Binding Affinities Measured by Native Nano ESI-MS: A Systematic Study.

    PubMed

    Gavriilidou, Agni F M; Glbakan, Basri; Zenobi, Renato

    2015-10-20

    Native electrospray ionization (ESI) mass spectrometry (MS) is a powerful technique for analyzing biomolecules in their native state. However, ESI-MS is incompatible with nonvolatile solution additives. Therefore, biomolecules have to be electrosprayed from a solution that differs from their purification or storage buffer, often aqueous ammonium acetate (AmAc). In this study, the effect of the ionic strength on the dissociation constants of six different noncovalent complexes, that cover interactions present in many biological systems, was investigated. Complexes were electrosprayed from 10 mM, 50 mM, 100 mM, 300 mM, and 500 mM aqueous AmAc. For all systems, it was shown that the binding affinity is significantly influenced by the ionic strength of the solution. The determined dissociation constant (Kd) was affected more than 50% when increasing the AmAc concentration. The results are interpreted in terms of altered ionic interactions induced by the solution. This work emphasizes the modulating effect of the ions on noncovalent interactions and the importance of carefully choosing the AmAc concentration for quantifying the receptor-ligand binding strengths. PMID:26399292

  10. 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. PMID:25562466

  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. PMID:27178940

  12. 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

  13. Biodegradable cellulose acetate nanofiber fabrication via electrospinning.

    PubMed

    Christoforou, Theopisti; Doumanidis, Charalabos

    2010-09-01

    Nanofiber manufacturing is one of the key advancements in nanotechnology today. Over the past few years, there has been a tremendous growth of research activities to explore electrospinning for nanofiber formation from a rich variety of materials. This quite simple and cost effective process operates on the principle that the solution is extracted under the action of a high electric field. Once the voltage is sufficiently high, a charged jet is ejected following a complicated looping trajectory. During its travel, the solvent evaporates leaving behind randomly oriented nanofibers accumulated on the collector. The combination of their nanoscale dimensionality, high surface area, porosity, flexibility and superior strength makes the electrospun fibers suitable for several value-added applications, such as filters, protecting clothes, high performance structures and biomedical devices. In this study biodegradable cellulose acetate (CA) nanofibrous membranes were produced using electrospinning. The device utilized consisted of a syringe equipped with a metal needle, a microdialysis pump, a high voltage supply and a collector. The morphology of the yielded fibers was determined using SEM. The effect of various parameters, including electric field strength, tip-to-collector distance, solution feed rate and composition on the morphological features of the electrospun fibers was examined. The optimum operating conditions for the production of uniform, non-beaded fibers with submicron diameter were also explored. The biodegradable CA nanofiber membranes are suitable as tissue engineering scaffolds and as reinforcements of biopolymer matrix composites in foils by ultrasonic welding methods. PMID:21133179

  14. Thin La{sub 2}Zr{sub 2}O{sub 7} films made from a water-based solution

    SciTech Connect

    Cloet, V. Feys, J.; Huehne, R.; Hoste, S.; Van Driessche, I.

    2009-01-15

    Thin films of La{sub 2}Zr{sub 2}O{sub 7} (LZO) are highly regarded as possible buffer layers in the coated conductor configuration. This report describes a new synthesis for thin crystalline LZO films, based on a largely water-based solution, mainly containing metal acetates, acetic acid and an organic amine-base: triethanolamine. Initially, a thin layer of amorphous material is deposited on the textured Ni-5 at%W substrate by means of dip-coating. Only by careful control of the thermal treatment can the layer be transformed into a crystalline layer. Important parameters in this respect are the heating rate and the dwell time. The amorphous gel is analysed by HR-TGA/DTA and HR-TEM. The textured layers are analysed by XRD, pole figures, RHEED, AFM and SEM. - Grapical Abstract: Thin films of La2Zr2O7 (LZO) are produced via a water-based solution, containing metal acetates, acetic acid and triethanolamine. The thin layer is deposited on the textured Ni-5 at%W substrate by dip-coating. The amorphous gel is analysed by HR-TGA/DTA and HR-TEM. The textured layers are analysed by XRD, pole figures, RHEED analysis, AFM and SEM.

  15. 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.

  16. 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

  17. Eliminating Cell Broadband Engine™ DMA Buffer Overflows

    NASA Astrophysics Data System (ADS)

    Murase, Masana

    This paper presents effective and efficient implementation techniques for DMA buffer overflow elimination on the Cell Broadband Engine™ (Cell/B.E.) processor. In the Cell/B.E. programming model, application developers manually issue DMA commands to transfer data from the system memory to the local memories of the Cell/B.E. cores. Although this allows us to eliminate cache misses or cache invalidation overhead, it requires careful management of the buffer arrays for DMA in the application programs to prevent DMA buffer overflows. To guard against DMA buffer overflows, we introduced safe DMA handling functions for the applications to use. To improve and minimize the performance overhead of buffer overflow prevention, we used three different optimization techniques that take advantage of SIMD operations: branch-hint-based optimizations, jump-table-based optimizations and self-modifying-based optimizations. Our optimized implementation prevents all DMA buffer overflows with minimal performance overhead, only 2.93% average slowdown in comparison to code without the buffer overflow protection.

  18. The possible role of acetate in exercise hyperemia in dog skeletal muscle.

    PubMed

    Steffen, R P; McKenzie, J E; Haddy, F J

    1982-02-01

    The possible role of acetate in the genesis of exercise hyperemia was studied in five series of dogs. Intraarterial infusion of an isomotic solution of sodium acetate at 0.76 ml/min in the dog forelimb decreased the resistance to flow through skeletal muscle by 48%, primarily by decreasing resistance to flow through small vessels. Skin lymph flow and lymph protein concentration were unaffected. The hindlimb of the conscious dog took up acetate at rest (A-V difference, + 58.3 +/- 19.6 nmoles/ml) and put out acetate during treadmill exercise (A-V difference, -105.6 +/- 20.12 nmoles/ml); femoral venous blood acetate concentration increased by 145 nmoles/ml (control 195 nmoles/ml). In the gracilis muscle of the anesthetized dog, simulated exercise at 0.5, 1.0 or 2.0 Hz increased acetate tissue content (72, 248 and 442 nmoles/g, respectively), output (18,899, and 1,830 nmoles/100 g/min, respectively) and venous concentration (82, 49 and 39 nmoles/ml, respectively) and changes in tissue acetate content correlated with changes in vascular resistance r = 0.75, P less than 0.001. Intraarterial infusion of an isosmotic solution of sodium acetate in the quiescent gracilis muscle perfused at constant flow produced a significant (6%) decrease in resistance when arterial blood acetate was increased by a calculated 96 nmoles/ml. These studies suggest that acetate might be included among those metabolites that contribute to exercise hyperemia.U PMID:7070963

  19. Different Protonation Equilibria of 4-Methylimidazole and Acetic Acid

    SciTech Connect

    Gu, Wei; Helms, Volkhard H.

    2007-12-03

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Dynamic protonation equilibria in water of one 4-methylimidazole molecule as well as for pairs and groups consisting of 4- methylimidazole, acetic acid and bridging water molecules are studied using Q-HOP molecular dynamics simulation. We find a qualitatively different protonation behavior of 4-methylimidazole compared to that of acetic acid. On one hand, deprotonated, neutral 4-methylimidazole cannot as easily attract a freely diffusing extra proton from solution. Once the proton is bound, however, it remains tightly bound on a time scale of tens of nanoseconds. In a linear chain composed of acetic acid, a separating water molecule and 4-methylimidazole, an excess proton is equally shared between 4-methylimidazole and water. When a water molecule is linearly placed between two acetic acid molecules, the excess proton is always found on the central water. On the other hand, an excess proton in a 4-methylimidazole-water- 4-methylimidazole chain is always localized on one of the two 4- methylimidazoles. These findings are of interest to the discussion of proton transfer along chains of amino acids and water molecules in biomolecules.

  20. 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.

  1. 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.

  2. 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. PMID:25640720

  3. 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. PMID:23420583

  4. CRYSTAL AND MOLECULAR STRUCTURE OF 6,6´-DIMETHOXY-GOSSYPOL:ACETIC ACID (1:1)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    By crystallization from dilute solutions of acetic acid (2-4%) in diethyl ether, acetone, or methyl ethyl ketone, 6,6´-dimethoxy-gossypol forms an inclusion complex with acetic acid in a one-to-one molar ratio. The compound crystallizes in the triclinic P1bar1¯space group and has unit cell dimensio...

  5. A MICROPROCESSOR ASCII CHARACTER BUFFERING SYSTEM

    EPA Science Inventory

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

  6. Buffer layer for thin film structures

    DOEpatents

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

    2010-06-15

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

  7. 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.

  8. Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase

    PubMed Central

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

    2014-01-01

    Background It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. Materials and methods We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes’ ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. Results The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. Conclusion These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion. PMID:24333060

  9. Positron scattering from vinyl acetate

    NASA Astrophysics Data System (ADS)

    Chiari, L.; Zecca, A.; Blanco, F.; García, G.; Brunger, M. J.

    2014-09-01

    Using a Beer-Lambert attenuation approach, we report measured total cross sections (TCSs) for positron scattering from vinyl acetate (C4H6O2) in the incident positron energy range 0.15-50 eV. In addition, we also report an independent atom model with screening corrected additivity rule computation results for the TCSs, differential and integral elastic cross sections, the positronium formation cross section and inelastic integral cross sections. The energy range of these calculations is 1-1000 eV. While there is a reasonable qualitative correspondence between measurement and calculation for the TCSs, in terms of the energy dependence of those cross sections, the theory was found to be a factor of ˜2 larger in magnitude at the lower energies, even after the measured data were corrected for the forward angle scattering effect.

  10. 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. PMID:26428454

  11. 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.

  12. 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.

  13. Buffer regulation of calcium puff sequences

    NASA Astrophysics Data System (ADS)

    Fraiman, Daniel; Ponce Dawson, Silvina

    2014-02-01

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

  14. Target buffer assessment for accelerator driven transmuters.

    SciTech Connect

    Gohar, Y.

    2002-10-08

    Accelerator driven transmuters use a buffer region to protect the structural and the cladding materials of the transmuter from the radiation damage caused by the high-energy spallation neutrons, to accommodate the coolant channels of the self cooled targets, and to have an insignificant effect on the neutron utilization for the transmutation process. These functions are contradicting with respect to the buffer thickness. An extension of the target region in the axial direction (the proton beam direction) is also required to act as a neutron multiplier for the forward component of the high-energy spallation neutrons and a reflector to minimize the neutron leakage. The buffer assessment was performed as a function of its thickness with different proton energies for a self-cooled Lead-Bismuth Eutectic and a sodium-cooled tungsten targets. The analyses show that the number of generated neutrons per proton has a low sensitivity to the buffer thickness. However, the number of neutrons reaching the transmuter is significantly reduced as the buffer thickness is increased. The transmuter neutrons dominate the nuclear responses in the structural material outside the target buffer. The length of the axial target extension is determined as a function of the proton beam energy.

  15. Spatial calcium buffering in saccular hair cells.

    PubMed

    Roberts, W M

    1993-05-01

    The potential importance of intracellular calcium-binding proteins in rapid and highly localized Ca2+ signalling is poorly understood. During fast synaptic transmission, which occurs at specialized active zones where Ca2+ diffuses only a few tens of nanometers from channels to neurotransmitter release sites, a cytoplasmic Ca2+ buffer would have to be extremely fast or present in millimolar concentrations to intercept a significant fraction of the calcium ions en route to their targets. Therefore, Ca2+ buffers have been presumed to be unimportant in fast exocytosis and another fast calcium-mediated process, electrical resonance in hair cells. Here I present evidence to the contrary by showing that hair cells in the frog sacculus contain millimolar concentrations of a mobile cytoplasmic calcium buffer that captures Ca2+ within a few microseconds after it enters through presynaptic Ca2+ channels and carries it away from the point of entry. This spatial buffering reduces the presynaptic free Ca2+ by up to 60 per cent and probably restricts the region in which the internal calcium ion concentration exceeds 1 microM to within < 250 nm of each synaptic site. The buffer can thus influence both electrical resonance and synaptic transmission. Calbindin-D28K or a related protein may serve as the mobile calcium buffer, an action similar to its function in transporting Ca2+ across intestinal epithelial cells. PMID:8479539

  16. Complexes of horseradish peroxidase with formate, acetate, and carbon monoxide.

    PubMed

    Carlsson, Gunilla H; Nicholls, Peter; Svistunenko, Dimitri; Berglund, Gunnar I; Hajdu, Janos

    2005-01-18

    Carbon monoxide, formate, and acetate interact with horseradish peroxidase (HRP) by binding to subsites within the active site. These ligands also bind to catalases, but their interactions are different in the two types of enzymes. Formate (notionally the "hydrated" form of carbon monoxide) is oxidized to carbon dioxide by compound I in catalase, while no such reaction is reported to occur in HRP, and the CO complex of ferrocatalase can only be obtained indirectly. Here we describe high-resolution crystal structures for HRP in its complexes with carbon monoxide and with formate, and compare these with the previously determined HRP-acetate structure [Berglund, G. I., et al. (2002) Nature 417, 463-468]. A multicrystal X-ray data collection strategy preserved the correct oxidation state of the iron during the experiments. Absorption spectra of the crystals and electron paramagnetic resonance data for the acetate and formate complexes in solution correlate electronic states with the structural results. Formate in ferric HRP and CO in ferrous HRP bind directly to the heme iron with iron-ligand distances of 2.3 and 1.8 A, respectively. CO does not bind to the ferric iron in the crystal. Acetate bound to ferric HRP stacks parallel with the heme plane with its carboxylate group 3.6 A from the heme iron, and without an intervening solvent molecule between the iron and acetate. The positions of the oxygen atoms in the bound ligands outline a potential access route for hydrogen peroxide to the iron. We propose that interactions in this channel ensure deprotonation of the proximal oxygen before binding to the heme iron. PMID:15641789

  17. 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.

  18. 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.

  19. 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.

  20. STABILITY OF CEFPIROME SULFATE IN AQUEOUS SOLUTIONS.

    PubMed

    Zalewski, Przemysław; Jelińska, Anna; Paczkowska, Magdalena; Garbacki, Piotr; Talaczyńska, Alicja; Stfpniak, Piotr; Cielecka-Piontek, Judyta

    2016-01-01

    The influence of pH on the stability of cefpirome sulfate was investigated in the pH range of 0.44 - 13.00. The degradation of cefpirome sulfate as a result of hydrolysis was a pseudo-first-order reaction. General acid-base hydrolysis of cefpirome sulfate was not observed. In the solutions of hydrochloric acid, sodium hydroxide, acetate, borate and phosphate buffer, k(obs) = k(pH) because specific acid-base catalysis was observed. Specific acid-base catalysis of cefpirome sulfate consisted of the following reactions: hydrolysis of cefpirome sulfate catalyzed by hydrogen ions (kH+), hydrolysis of dications (k₁H₂O) monocations (k₂ H₂O), zwitter ions (k₃H₂O) and monoanions (k₄ H₂O) of cefpirome sulfate under the influence of water. The total rate of the reaction was equal to the sum of partial reactions k(pH) = kH+ x aH+ + kH₂O x f₁ + k₂H₂O x f₂ + k₃H₂O x f₃ + k₄ H₂O x f₄. Based on the dependence k(pH) = f(pH) it was found that cefpirome sulfate was the most stable in aqueous solutions in the pH range of 4-6. PMID:27008797

  1. Stability of cefozopran hydrochloride in aqueous solutions.

    PubMed

    Zalewski, Przemysław; Skibiński, Robert; Paczkowska, Magdalena; Garbacki, Piotr; Talaczyńska, Alicja; Cielecka-Piontek, Judyta; Jelińska, Anna

    2016-04-01

    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. PMID:26079426

  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. 21 CFR 522.960b - Flumethasone acetate solution.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Conditions of use in dogs—(1) Amount. Administer by intramuscular injection as follows: Dogs weighing up to... noted. Dosage by injection should not exceed 3 days of therapy. With chronic conditions...

  4. 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 ...

  5. 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.

  6. Buffer Standards for the Physiological pH of the Zwitterionic Compound, DIPSO from 5 to 55°C

    PubMed Central

    Roy, Lakshmi N.; Roy, Rabindra N.; LeNoue, Sean R.; Denton, Cole E.; Fuge, Michael S.; Dunseth, Craig D.; Roy, Chandra N.; Hayden, Shawn M.; Wollen, Joshua T.; Sreepada, Kripa

    2009-01-01

    The values of the second dissociation constant, pK2, and related thermodynamic quantities of 3-[N,N-bis (2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO) have already been reported over the temperature range 5 to 55°C including 37°C. This paper reports the pH values of four NaCl-free buffer solutions and four buffer composition containing NaCl salt at I = 0.16 mol·kg−1. Conventional paH values are reported for all eight buffer solutions. The operational pH values have been calculated for four buffer solutions recommended as pH standards, at 25 and 37°C after correcting the liquid junction potentials with the flowing junction cell. PMID:20160870

  7. Production and utilization of acetate in mammals.

    PubMed

    Knowles, S E; Jarrett, I G; Filsell, O H; Ballard, F J

    1974-08-01

    1. In an attempt to define the importance of acetate as a metabolic precursor, the activities of acetyl-CoA synthetase (EC 6.2.1.1) and acetyl-CoA hydrolase (Ec 3.1.2.1) were assayed in tissues from rats and sheep. In addition, the concentrations of acetate in blood and liver were measured, as well as the rates of acetate production by tissue slices and mitochondrial fractions of these tissues. 2. Acetyl-CoA synthetase occurs at high activities in heart and kidney cortex of both species as well as in rat liver and the sheep masseter muscle. The enzyme is mostly in the cytosol fraction of liver, whereas it is associated with the mitochondrial fraction in heart tissue. Both mitochondrial and cytosol activities have a K(m) for acetate of 0.3mm. Acetyl-CoA synthetase activity in liver was not altered by changes in diet, age or alloxan-diabetes. 3. Acetyl-CoA hydrolase is widely distributed in rat and sheep tissues, the highest activity being found in liver. Essentially all of the activity in liver and heart is localized in the mitochondrial fraction. Hepatic acetyl-CoA hydrolase activity is increased by starvation in rats and sheep and during the suckling period in young rats. 4. The concentrations of acetate in blood are decreased by starvation and increased by alloxan-diabetes in both species. The uptake of acetate by the sheep hind limb is proportional to the arterial concentration of acetate, except in alloxan-treated animals, where uptake is impaired. 5. Acetate is produced by liver and heart slices and also by heart mitochondrial fractions that are incubated with either pyruvate or palmitoyl-(-)-carnitine. Liver mitochondrial fractions do not form acetate from either substrate but instead convert acetate into acetoacetate. 6. We propose that acetate in the blood of rats or starved sheep is derived from the hydrolysis of acetyl-CoA. Release of acetate from tissues would occur under conditions when the function of the tricarboxylic acid cycle is restricted, so that the circulating acetate serves to redistribute oxidizable substrate throughout the body. This function is analogous to that served by ketone bodies. PMID:4441381

  8. 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…

  9. 12 CFR 3.11 - Capital conservation buffer and countercyclical capital buffer amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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

  10. 12 CFR 217.11 - Capital conservation buffer and countercyclical capital buffer amount.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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

  11. Acetate complexes as an illustration of metal-organic interactions in groundwater and sedimentary basin brines

    SciTech Connect

    Koretsky, C.M.; Shock, E.L. . Earth and Planetary Sciences Dept.)

    1993-03-01

    It has been nearly two decades since Willey et al and Carothers and Kharaka generated considerable interest in complex formation between metal cations and organic acid ligands by their reports of high concentrations of acetate and other carboxylic acid anions in oilfield brines. In the present study, estimates of standard partial molal properties at high temperatures and pressures for aqueous acetate complexes of major and trace elements in geologic fluids were made with the aid of experimental data from the literature and correlation algorithms. Thermodynamic data and equation-of-state parameters permit calculation of standard partial molal properties, including dissociation constants, for 115 acetate complexes. Incorporation of many of these dissociation constants with those for hydroxide, chloride and sulfate complexes demonstrate that acetate complexes are ineffectual in transporting major-rock-forming elements or trace metals in sedimentary basin brines. In contrast, acetate complexes could be considerably more efficient for metal transport in low salinity groundwater solutions containing elevated concentrations of organic solutes. Speciation calculations for a hypothetical oilfield brine of average composition indicate that up to 40% of the acetate may be present as sodium and calcium complexes in basinal brines with total salinities around 1.0 molal. The conclusions of these calculations for hypothetical oilfield brines are confirmed by speciation calculations for a natural brine from the Frio formation of the Texas Gulf Coast using analytical data for inorganic constituents reported by Kharaka et al. and carboxylic acids given by Carothers and Kharaka (1978).

  12. 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. PMID:26807118

  13. 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

  14. Acetate- and Citrate-Specific Ion Effects on Unfolding and Temperature-Dependent Aggregation Rates of Anti-Streptavidin IgG1.

    PubMed

    Barnett, Gregory V; Razinkov, Vladimir I; Kerwin, Bruce A; Hillsley, Alexander; Roberts, Christopher J

    2016-03-01

    Controlling and predicting unwanted degradation, such as non-native aggregation, is a long-standing challenge for mAbs and other protein-based products. mAb aggregation rates are typically sensitive to temperature, pH, and the addition of excipients. Quantitatively comparing temperature-dependent aggregation rates across multiple possible formulations is a challenge in product development. A parallel temperature initial rate method is used to efficiently and accurately determine initial rates for anti-streptavidin (AS) IgG1 aggregation as a function of pH, [NaCl], and in the presence of acetate versus citrate buffer. Parallel temperature initial rates are shown to agree with results from a traditional, isothermal method and permits direct comparison of the formulations across almost 3 orders of magnitude of aggregation rates. The apparent midpoint unfolding temperatures (through differential scanning calorimetry) and the effective activation energy values (Ea) are generally higher in acetate buffer compared with citrate buffer, which is consistent with preferential accumulation of citrate ions compared with acetate ions that was speculated in previous work (Barnett et al., J Phys Chem B, 2015). Static light scattering and Kirkwood-Buff analysis show that AS-IgG1 has stronger net repulsive protein-protein interactions in acetate compared with citrate buffer, also consistent with increased values of Ea. In an extreme case, aggregation of AS-IgG1 is effectively eliminated across all practical temperatures at pH 4 in 10 mM sodium acetate but proceeds readily in citrate buffer. PMID:26886346

  15. Riparian forests buffer panel final report

    SciTech Connect

    1996-10-01

    The Chesapeake Executive Council adopted Directive 94-1 which called upon the Chesapeake Bay Program to develop a set of goals and actions to increase the focus on riparian stewardship and enhance efforts to conserve and restore riparian forest buffers. The Council appointed a panel to recommend a set of policies, recommend an accepted definition of forest buffers, and suggest quantifiable goals. The Panel was a diverse group of thirty-one members, comprised of federal, state, and local government representatives, scientists, land managers, citizens, and farming, development, forest industry, and environmental interests. This report contains our principal findings and recommendations.

  16. Dehydration of acetic acid-water mixtures with near critical and supercritical fluid solvents

    SciTech Connect

    McCully, M.A.; Mullins, J.C.; Thies, M.C.; Hartley, I.J.

    1988-10-01

    Equilibrium tie lines and phase densities are presented for acetic acid-water mixtures with near critical propane at 361K and 52 bar. Experimental measurements were obtained with a static technique; the equilibrium phases were directly sampled with high-pressure liquid sample injection valves at the temperature and pressure of interest. The data obtained in this work indicate that near critical propane can be used to facilitate the production of glacial acetic acid from dilute acetic acid-water solutions. Both these experimental data and the authors earlier results for acetic acid-water mixtures with supercritical carbon dioxide have been used to test an equation of state which has recently been developed by Grenzheuser and Gmehling for systems which contain associating fluids. Results indicate that the equation's pure component parameters need to be refitted to represent the critical region more accurately.

  17. Acetate metabolism and aging: An emerging connection.

    PubMed

    Shimazu, Tadahiro; Hirschey, Matthew D; Huang, Jing-Yi; Ho, Linh T Y; Verdin, Eric

    2010-01-01

    Sirtuins are NAD(+)-dependent protein deacetylases that regulate gene silencing, energy metabolism and aging from bacteria to mammals. SIRT3, a mammalian mitochondrial sirtuin, deacetylates acetyl-CoA synthetase (AceCS2) in the mitochondria. AceCS2 is conserved from bacteria to humans, catalyzes the conversion of acetate to acetyl-CoA and enables peripheral tissues to utilize acetate during fasting conditions. Here, we review the regulation of acetate metabolism by sirtuins, the remarkable conservation of this metabolic regulatory pathway and its emerging role in the regulation of aging and longevity. PMID:20478325

  18. Conversion to eslicarbazepine acetate monotherapy

    PubMed Central

    French, Jacqueline; Jacobson, Mercedes P.; Pazdera, Ladislav; Gough, Mallory; Cheng, Hailong; Grinnell, Todd; Blum, David

    2016-01-01

    Objective: To assess the efficacy and safety of eslicarbazepine acetate (ESL) monotherapy. Methods: This post hoc pooled analysis of 2 randomized double-blind studies (093-045 and -046) included adults with partial-onset seizures medically uncontrolled by 1 or 2 antiepileptic drugs (AEDs). Following the baseline period (8 weeks), eligible patients were randomized 2:1 to receive ESL 1,600 mg or 1,200 mg once daily for 18 weeks; the primary endpoint was study exit by meeting predefined exit criteria (signifying worsening seizure control). In each study, treatment was considered effective if the upper 95% confidence limit for exit rate was lower than the historical control threshold (65.3%). Results: Pooled exit rates were as follows: ESL 1,600 mg = 20.6% (95% confidence interval: 15.6%–26.8%); ESL 1,200 mg = 30.8% (23.0%–40.5%). Use of 2 baseline AEDs or rescue medication, US location, epilepsy duration ≥20 years, and higher maximum baseline seizure frequency were associated with higher exit risks. Median percent reductions in standardized seizure frequency between baseline and the 18-week double-blind period were as follows: ESL 1,600 mg = 43.2%; ESL 1,200 mg = 35.7%; baseline carbamazepine use was associated with smaller reductions. Safety profiles were similar between ESL doses. Conclusions: Exit rates for ESL monotherapy (1,600 mg and 1,200 mg once daily) were lower than the historical control threshold, irrespective of baseline AED use and region, with no additional safety concerns identified. Clinical factors and location clearly influence treatment responses in conversion-to-monotherapy trials. Classification of evidence: This pooled analysis provides Class IV evidence that for adults with medically uncontrolled partial-onset seizures, ESL monotherapy is well tolerated and effective. PMID:26911639

  19. The pharmacology of nomegestrol acetate.

    PubMed

    Ruan, Xiangyan; Seeger, Harald; Mueck, Alfred O

    2012-04-01

    Nomegestrol acetate (NOMAC) is a 19-norprogesterone derivative with high biological activity at the progesterone receptor, a weak anti-androgenic effect, but with no binding to estrogen, glucocorticoid or mineralocorticoid receptors. At dosages of 1.5mg/day or more, NOMAC effectively suppresses gonadotropic activity and ovulation in women of reproductive age. Hemostasis, lipids and carbohydrate metabolism remain largely unchanged. In normal and cancerous human breast cells, NOMAC has shown favorable effects on estrogen metabolism. Like natural progesterone (but in contrast to some other synthetic progestogens), it does not appear stimulate the proliferation of cancerous breast cells. While there has been some experience of the use of NOMAC in combination with estrogens as a hormone replacement therapy, most of the data on the compound are reported in the context of its inclusion as a component of a new contraceptive pill comprising 2.5mg NOMAC combined with 1.5mg estradiol. Because of its strong endometrial efficacy, and due to its high antigonadotropic activity and long elimination half-life (about 50h), the contraceptive efficacy of the new pill is maintained even when dosages are missed. Furthermore, for the first time with a monophasic 24/4 regimen containing estradiol, cyclical stability can be achieved comparable with that obtained using pills containing ethinyl estradiol and progestogens like levonorgestrel or drospirenone. The addition of NOMAC to estradiol means that the beneficial effects of estrogen are not lost, which is of especial importance in relation to the cardiovascular system. On the basis both of its pharmacology and of studies performed during the development of the NOMAC/estradiol pill, involving some 4000 women in total, good long-term tolerability can be expected for NOMAC, although its safety profile is still to be fully ascertained, as the clinical endpoint studies are yet to be completed. PMID:22364709

  20. Anaerobic model for high-solids or high-temperature digestion - additional pathway of acetate oxidation.

    PubMed

    Wett, B; Takács, I; Batstone, D; Wilson, C; Murthy, S

    2014-01-01

    Current anaerobic digestion models cannot properly simulate processes that are operated under high solids concentrations or high temperatures. A modification to existing models has been implemented by adding important missing degradation pathways, to accommodate these systems without artificially recalibrating the model parameters. Specifically, we implemented the alternate acetate oxidizing mechanism that is more tolerant to ammonia than the standard aceticlastic pathway. Inhibition values were estimated and an empirical function has been used to apply ammonia inhibition. The model also relates metabolic activity to un-ionised species such as undissociated acetic acid as substrate (although not obligatory for all organisms) and unionised ammonia as inhibitor. The model relies on an equilibrium chemistry module (e.g. including the phosphate buffer), resulting in more accurate pH predictions, which is crucial for proper modeling of CO2 and NH3 stripping. Calibration results from three case-studies modeling thermal hydrolysis and subsequent digestion of sludge are presented. PMID:24759522

  1. 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.

  2. Density functional theory study of selective deacylation of aromatic acetate in the presence of aliphatic acetate under ammonium acetate mediated conditions.

    PubMed

    Xia, Shijing; Zhang, Haoyu

    2014-07-01

    Aromatic acetates can be selectively deprotected in the presence of aliphatic acetates under ammonium acetate mediated condition. B3LYP/6-31++G** level of theory was demonstrated to be successfully used to model the relative reaction rates for deacylation reactions for aliphatic and aromatic ester systems. On the basis of the mechanistic studies, acetate anion is most likely to be the active catalyst for the ester deacylation reactions under ammonium acetate mediated condition. PMID:24956355

  3. A new process for producing calcium acetate from vegetable wastes for use as an environmentally friendly deicer.

    PubMed

    Jin, Fangming; Zhang, Guangyi; Jin, Yujia; Watanabe, Yosiyuki; Kishita, Atsushi; Enomoto, Heiji

    2010-10-01

    A new process for producing calcium acetate, a non-corrosive deicer, is proposed. The process consists of a two-step continuous-flow hydrothermal conversion of vegetable wastes into acetic acid and the production of calcium acetate, followed by the separation and condensation of the product. The experiments for acetic acid production showed that there were almost no significant differences in acetic acid yields for the five different kinds of vegetables selected for the batch experiments or for their mixture in batch and continuous-flow experiments. Electrodialysis was chosen as a satisfactory method for separating and condensing the calcium acetate produced from the acetic acid solution obtained from the vegetable wastes. After purification by reverse-osmosis, the residual, depleted acid solution could be safely discharged. The calculation of the carbon balance for the proposed process showed that 21.3% of the TOC from vegetable wastes could be used as calcium/magnesium acetate (CMA) and over 22% as an environmentally friendly deicer. PMID:20483594

  4. Tris-acetate polyacrylamide gradient gels for the simultaneous electrophoretic analysis of proteins of very high and low molecular mass.

    PubMed

    Cubillos-Rojas, Monica; Amair-Pinedo, Fabiola; Tato, Irantzu; Bartrons, Ramon; Ventura, Francesc; Rosa, Jose Luis

    2012-01-01

    Polyacrylamide gel electrophoresis (PAGE) is one of the most powerful tools used for protein analysis. We describe the use of Tris-acetate buffer and 3-15% polyacrylamide gradient gels to simultaneously separate proteins in the mass range of 10-500 kDa. We show that this system is highly sensitive, it has good resolution and high reproducibility, and that it can be used for general applications of PAGE such as Coomassie Brilliant Blue staining and immunoblotting. Moreover, we describe how to generate mini Tris-acetate polyacrylamide gels to use them in miniprotein electrophoresis systems. These economical gels are easy to generate and to manipulate and allow a rapid analysis of proteins. All these features make the Tris-acetate-PAGE system a very helpful tool for protein analysis. PMID:22585488

  5. Kinetic model of acetate metabolism in healthy and hyperinsulinaemic humans

    PubMed Central

    Fernandes, Judlyn; Vogt, Janet; Wolever, Thomas MS

    2014-01-01

    Background/objectives The short chain fatty acid acetate (AC), may play a role in increasing insulin sensitivity, thus lowering risk for obesity and type 2 diabetes mellitus. It is unclear if AC kinetics is similar in normal and hyperinsulinaemic participants. Therefore, we studied AC absorption from the distal colon in participants with normal (<40 pmol/L, NI) and high (≥40 pmol/L, HI) plasma-insulin. This work was part of a series of studies conceived to compute a kinetic model for acetate. Kinetic parameters such as estimates of rate of entry into peripheral blood, hepatic uptake and endogenous/exogenous production were compared in the groups. Subjects/methods Overnight fasted NI (n = 9) and HI (n = 8) participants were given rectal infusions containing sodium acetate (90 mmol/L). The solutions were retained for 40 min, then voided for AC measurement. Total amount of AC infused was 27 mmols. Results Acetate absorption from the distal colon (279±103 vs 322±91 μmol/min, P = 0.76) and hepatic uptake of AC (155±101 vs 146±85 μmol/min, P = 0.94) were similar in the groups. Endogenous and exogenous AC production was significantly higher in NI than HI participants. Plasma AC was inversely proportional to plasma insulin concentrations in the entire cohort (y=k/x, where k = 1813). Conclusions There was low power to detect differences in AC absorption rate and hepatic AC uptake in NI vs HI. The rate of entry of AC into peripheral blood was similar in NI and HI participants. However, hyperinsulinaemia may alter endogenous and exogenous AC metabolism. PMID:25052228

  6. Ferroelectric thin film bismuth titanate prepared from acetate precursors

    SciTech Connect

    Lu, Yanxia; Hoelzer, D.T.; Schulze, W.A.; Tuttle, B.A.; Potter, B.G.

    1994-10-01

    Bismuth titanate (Bi{sub 4}Ti{sub 3}O{sub 12}) thin films were fabricated by spin coat deposition followed by rapid thermal processing (RTP). Acetate derived solutions for deposition were synthesized by blending bismuth acetate in aqueous acetic acid and then adding titanium acetate. A series of electrically insulating, semiconducting and conducting substrates were evaluated for Bi{sub 4}Ti{sub 3}O{sub 12} film deposition. While X-ray diffraction and TEM analyses indicated that the initial perovskite crystallization temperature was 500{degrees}C or less for these Bi{sub 4}Ti{sub 3}O{sub 12} films, a 700{degrees}C crystallization treatment was used to obtain single phase perovskite films. Bi{sub 4}Ti{sub 3}O{sub 12} film crystallographic orientation was shown to depend on three factors: substrate surface morphology, the number of coating layers and thermal processing. While preferred c-direction orientation was observed for Bi{sub 4}Ti{sub 3}O{sub 12} films deposited on silver foil substrates, preferred a-direction orientation was obtained for films deposited on both Si and Pt coated Si wafers. The films were dense, smooth, crack free, and had grain sizes ranging from 20 nm to 100 nm. Film thickness and refractive index were determined using a combination of ellipsometry, waveguide refractometry and TEM measurements. Both low field dielectric and ferroelectric properties were measured for an 800 nm thick film deposited on a Pt coated MgO substrate. A remanent polarization of 38 {mu}C/cm{sup 2} and a coercive field of 98 kV/cm were measured for this film that was crystallized at 700{degrees}C.

  7. 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...

  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. 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

  10. 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…

  11. 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)

  12. 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.

  13. Phosphorus Uptake During Four Years by Different Vegetative Cover Types in a Riparian Buffer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetative buffers have been shown to reduce nutrient loss associated with the transport of detached soil particles and may through plant uptake offer a means to capture dissolved nutrients moving to surface waters through the soil solution. The objective of this 4-year study was to evaluate change...

  14. Peptide-catalyzed, bioinspired silicification for single-cell encapsulation in the imidazole-buffered system.

    PubMed

    Park, Ji Hun; Choi, Insung S; Yang, Sung Ho

    2015-03-28

    Inspired by biosilicification of glass sponges, we designed a catalytic peptide, which formed silica structures in the imidazole-buffered solution. The peptide was adsorbed selectively onto the surface of yeast cells, and the bioinspired silicification led to the formation of a cytoprotective silica shell on individual yeast cells. PMID:25493325

  15. 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, organic matter and type of added carbonizated material. Our study showed that the biochar content has significant role in total pH buffer capacity in soil:biochar system . References. Kimetu, J.M., Lehmann, J., Ngoze, S.O., Mugendi, D.N., Kinyangi, J., Riha, S.J., Verchot, L., Recha, J.W., Pell, A.N. 2008. Reversibility of Soil Productivity Decline with Organic Matter of Differing Quality Along a Degradation Gradient. Ecosystems, 11, 726-739. Krull, E. S., Skjemstad, J.O., Baldock, J.A. 2004 'Functions of Soil Organic Matter and the Effect on Soil Properties'. GRDC report. Project CSO 00029. Mutezo, W.T., 2013. Early crop growth and yield responses of maize (Zea mays) to biochar applied on soil. International Working Paper Series, 13/03, 50 pp.

  16. Methanogenesis from acetate: a nonmethanogenic bacterium from an anaerobic acetate enrichment.

    PubMed

    Ward, D M; Mah, R A; Kaplan, I R

    1978-06-01

    A methanogenic acetate enrichment was initiated by inoculation of an acetate-mineral salts medium with domestic anaerobic digestor sludge and maintained by weekly transfer for 2 years. The enrichment culture contained a Methanosarcina and several obligately anaerobic nonmethanogenic bacteria. These latter organisms formed varying degrees of association with the Methanosarcina, ranging from the nutritionally fastidious gram-negative rod called the satellite bacterium to the nutritionally nonfastidious Eubacterium limosum. The satellite bacterium had growth requirements for amino acids, a peptide, a purine base, vitamin B12, and other B vitamins. Glucose, mannitol, starch, pyruvate, cysteine, lysine, leucine, isoleucine, arginine, and asparagine stimulated growth and hydrogen production. Acetate was neither incorporated nor metabolized by the satellite organism. Since acetate was the sole organic carbon source in the enrichment culture, organism(s) which metabolize acetate (such as the Methanosarcina) must produce substrates and growth factors for associated organisms which do not metabolize acetate. PMID:677881

  17. Nomegestrol acetate/estradiol: in oral contraception.

    PubMed

    Yang, Lily P H; Plosker, Greg L

    2012-10-01

    Nomegestrol acetate/estradiol is a combined oral contraceptive with approval in many countries. This fixed-dose combination tablet contains nomegestrol acetate, a highly selective progestogen, and estradiol, a natural estrogen. It is the first monophasic combined oral contraceptive to contain estradiol, and is taken in 28-day cycles, consisting of 24 active therapy days with 4 placebo days (i.e. 24/4-day cycles). In two large, 1-year, randomized, open-label, multicentre, phase III trials in healthy adult women (aged 18-50 years), nomegestrol acetate/estradiol was at least as effective as drospirenone/ethinylestradiol as contraceptive therapy, as the pregnancy rates in women aged 18-35 years (primary efficacy population) in terms of the Pearl Index (primary endpoint) were numerically lower with nomegestrol acetate/estradiol, although the between-group difference was not statistically significant. In both trials, nomegestrol acetate/estradiol was given in a 24/4-day cycle, and drospirenone/ethinylestradiol was given in a 21/7-day cycle. The criteria for using condoms in case of forgotten doses were less stringent in the nomegestrol acetate/estradiol group than in the drospirenone/ethinylestradiol group. Nomegestrol acetate/estradiol therapy for up to 1 year was generally well tolerated in healthy adult women, with an acceptable tolerability profile in line with that expected for a combined oral contraceptive. The most commonly reported adverse events were acne and abnormal withdrawal bleeding (most often shorter, lighter or absent periods). Overall, compared with drospirenone/ethinylestradiol, nomegestrol acetate/estradiol appeared to be associated with less favourable acne-related outcomes, and shorter, lighter or absent periods. PMID:22950535

  18. 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.

  19. 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.

  20. 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.

  1. Acetate limitation and nitrite accumulation during denitrification

    SciTech Connect

    Oh, J.; Silverstein, J.

    1999-03-01

    Nitrite accumulated in denitrifying activated sludge mixed liquor when the carbon and electron source, acetate, was limited. If acetate was added to obtain a carbon-to-nitrogen (C:N) ratio in the range of 2:1 to 3:1, nitrate was completely consumed at the same rate with no nitrite accumulation, indicating that nitrate concentration controlled the respiration rate as long as sufficient substrate was present. However, when acetate was reduced to a C:N ratio of 1:1, while nitrate continued to be consumed, > 50% of the initial nitrate-nitrogen accumulated as nitrite and 29% persisted as nitrite throughout an endogenous denitrification period of 8--9 h. While nitrite accumulated during acetate-limited denitrification, the specific nitrate reduction rate increased significantly compared with the rate when excess acetate was provided as follows: 0.034 mg-NO{sub 3}-N/mg-mixed liquid volatile suspended solids/h versus 0.023 mg-NO{sub 3}-N/mg-mixed liquid volatile suspended solids/h, respective. This may be explained by nitrate respiration out-competing nitrite respiration for limited acetate electrons. Complete restoration of balanced denitrification and elimination of nitrite accumulation during denitrification required several weeks after the C:N ratio was increased back to 2:1.

  2. Individual cells of Saccharomyces cerevisiae and Zygosaccharomyces bailii exhibit different short-term intracellular pH responses to acetic acid.

    PubMed

    Arneborg, N; Jespersen, L; Jakobsen, M

    2000-01-01

    The effects of perfusion with 2.7 and 26 mM undissociated acetic acid in the absence or presence of glucose on short-term intracellular pH (pH(i)) changes in individual Saccharormyces cerevisiae and Zygosaccharomyces bailii cells were studied using fluorescence-ratio-imaging microscopy and a perfusion system. In the S. cerevisiae cells, perfusion with acetic acid induced strong short-term pH(i) responses, which were dependent on the undissociated acetic acid concentration and the presence of glucose in the perfusion solutions. In the Z. bailii cells, perfusion with acetic acid induced only very weak short-term pH(i) responses, which were neither dependent on the undissociated acetic acid concentration nor on the presence of glucose in the perfusion solutions. These results clearly show that Z. bailii is more resistant than S. cerevisiae to short-term pH(i) changes caused by acetic acid. PMID:10985752

  3. 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

  4. Potential Efficiency of Riparian Vegetated Buffer Strips in Intercepting Soluble Compounds in the Presence of Subsurface Preferential Flows.

    PubMed

    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

  5. Micronized fibres affect in vitro fermentation under normal buffered and osmotic stress conditions using porcine inocula.

    PubMed

    Aumiller, T; Mosenthin, R; Rink, F; Hartung, K; Weiss, E

    2015-12-01

    In this in vitro study, the modified Hohenheim gas test was used to determine fermentation activity and bacterial composition of pig's faecal microbial inoculum, when fermenting a standard pig diet with varying levels of crude protein (CP; 20, 24 and 28% CP), and supplemented with one of three fibre sources manufactured by micronization treatment. These were wheat envelopes (MWE), pea fibre (MPF) and lupine fibre (MLF). For comparison, inulin was used. As intestinal bacteria have to cope with varying osmotic conditions in their ecosystem, fermentation was performed under normal buffered and osmotic stress conditions. After 24 h of fermentation, total gas production and ammonia production were measured. In addition, the effect of MWE and inulin on short-chain fatty acid (SCFA) production and numbers of total eubacteria, Lactobacillus spp., Bifidobacterium spp., Enterobacteriaceae, Enterococcus spp., Clostridium cluster XIVa and Clostridium cluster IV, were determined using quantitative real-time PCR. Under normal buffered conditions, supplementation of MWE resulted in increased (p < 0.05) SCFA, acetic, propionic and valerianic acid production at CP levels of 20 and 28%. There was an increase (p < 0.05) in ammonia production for the micronized supplements, and for MWE an increased (p < 0.05) branched-chain proportion was observed, possibly due to higher availability of protein for fermentation which was released during the micronization process. Osmotic stress conditions reduced (p < 0.05) total gas as well as total SCFA, acetic and propionic acid production for all treatments, while cell counts were increased (p < 0.05) for Bifidobacterium spp., Enterococcus spp. and Lactobacillus spp. Under normal buffered conditions in combination with 24 and 28% CP levels, lactobacilli were increased for MWE, compared to inulin (p < 0.05). In conclusion, micronized supplements such as MWE may beneficially modulate pigs' intestinal microbiota by increasing SCFA production in addition to a selective proliferation of lactobacilli. PMID:25628046

  6. 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.

  7. Measurement of pH by NMR Spectroscopy in Concentrated Aqueous Fluoride Buffers

    PubMed Central

    Gerken, James B.

    2010-01-01

    An NMR spectroscopic technique has been developed to give rapid, accurate pH measurements on tenth-milliliter samples of concentrated acidic aqueous solutions buffered by fluoride ion in the pH 1.5 – 4.5 range. The fluoride 19F chemical shift has been calibrated as a function of pH at 0.1 and 1.0 M concentration by reference to an internal 3-fluoropyridine standard. Subsequent measurements of fluoride buffer pH required no additives and only two NMR spectra in the presence of an external reference standard. PMID:21278857

  8. Direct detection of the acetate-forming activity of the enzyme acetate kinase.

    PubMed

    Fowler, Matthew L; Ingram-Smith, Cheryl J; Smith, Kerry S

    2011-01-01

    Acetate kinase, a member of the acetate and sugar kinase-Hsp70-actin (ASKHA) enzyme superfamily, is responsible for the reversible phosphorylation of acetate to acetyl phosphate utilizing ATP as a substrate. Acetate kinases are ubiquitous in the Bacteria, found in one genus of Archaea, and are also present in microbes of the Eukarya. The most well characterized acetate kinase is that from the methane-producing archaeon Methanosarcina thermophila. An acetate kinase which can only utilize PP(i) but not ATP in the acetyl phosphate-forming direction has been isolated from Entamoeba histolytica, the causative agent of amoebic dysentery, and has thus far only been found in this genus. In the direction of acetyl phosphate formation, acetate kinase activity is typically measured using the hydroxamate assay, first described by Lipmann, a coupled assay in which conversion of ATP to ADP is coupled to oxidation of NADH to NAD(+) by the enzymes pyruvate kinase and lactate dehydrogenase, or an assay measuring release of inorganic phosphate after reaction of the acetyl phosphate product with hydroxylamine. Activity in the opposite, acetate-forming direction is measured by coupling ATP formation from ADP to the reduction of NADP(+) to NADPH by the enzymes hexokinase and glucose 6-phosphate dehydrogenase. Here we describe a method for the detection of acetate kinase activity in the direction of acetate formation that does not require coupling enzymes, but is instead based on direct determination of acetyl phosphate consumption. After the enzymatic reaction, remaining acetyl phosphate is converted to a ferric hydroxamate complex that can be measured spectrophotometrically, as for the hydroxamate assay. Thus, unlike the standard coupled assay for this direction that is dependent on the production of ATP from ADP, this direct assay can be used for acetate kinases that produce ATP or PP(i). PMID:22214984

  9. Acute intestinal injury induced by acetic acid and casein: prevention by intraluminal misoprostol

    SciTech Connect

    Miller, M.J.; Zhang, x.J.; Gu, x.A.; Clark, D.A. )

    1991-07-01

    Acute injury was established in anesthetized rabbits by intraluminal administration of acetic acid with and without bovine casein, into loops of distal small intestine. Damage was quantified after 45 minutes by the blood-to-lumen movement of {sup 51}Cr-labeled ethylenediaminetetraacetic acid (EDTA) and fluorescein isothiocyanate-tagged bovine serum albumin as well as luminal fluid histamine levels. The amount of titratable acetic acid used to lower the pH of the treatment solutions to pH 4.0 was increased by the addition of calcium gluconate. Luminal acetic acid caused a 19-fold increase in {sup 51}Cr-EDTA accumulation over saline controls; casein did not modify this effect. In saline controls, loop fluid histamine levels bordered on the limits of detection (1 ng/g) but were elevated 19-fold by acetic acid exposure and markedly increased (118-fold) by the combination of acid and casein. Intraluminal misoprostol (3 or 30 micrograms/mL), administered 30 minutes before acetic acid, significantly attenuated the increase in epithelial permeability (luminal {sup 51}Cr-EDTA, fluorescein isothiocyanate-bovine serum albumin accumulation) and histamine release (P less than 0.05). Diphenhydramine, alone or in combination with cimetidine, and indomethacin (5 mg/kg IV) were not protective. It is concluded that exposure of the epithelium to acetic acid promotes the transepithelial movement of casein leading to enhanced mast cell activation and mucosal injury. Damage to the epithelial barrier can be prevented by misoprostol.

  10. Strategic Buffer Layer Development for YBCO Coated Conductors

    SciTech Connect

    Paranthaman, Mariappan Parans; Aytug, Tolga; Kim, Kyunghoon; Specht, Eliot D; Heatherly Jr, Lee

    2009-01-01

    We have developed a simplified buffer layer architecture for the rolling-assisted biaxially textured substrates (RABiTS) template approach. The overall purpose of this research is to enable potentially a low-cost, high throughput and high yield manufacturing processes for buffer fabrication and to gain fundamental understanding of the growth of buffer layers for RABiTS templates. This understanding is critical to the development of a reliable, robust, and long-length manufacturing process for second generation wires. In this study, efforts are being made to either reduce the number of vacuum deposited layers or to replace one or more of these vacuum deposited layers with a solution based layer. We have chosen Gd{sub 2}O{sub 3} - ZrO{sub 2} system as a potential barrier layer for this study. We have deposited epitaxial Gadolinia Stabilized Zirconia (GSZ) (Zr{sub 1-x}Gd{sub x}O{sub y}; x = 0-1) films on 30-nm thick e-beam evaporated Y{sub 2}O{sub 3} seeded Ni-W (3 at. %) (Ni-3W) substrates using a metal-organic decomposition (MOD) process. Detailed X-ray studies indicated that all of the MOD-GSZ layers were cube textured and both in-plane and out-of-plane lattice parameters increases linearly with increasing the Gd content. We have also developed process conditions for reactively sputter deposited epitaxial Gd{sub 2}Zr{sub 2}O{sub 7} (Gadolinium Zirconium Oxide (GZO); Zr{sub 1-x}Gd{sub x}O{sub y} (x = 0.5)) films on the e-beam evaporated Y{sub 2}O{sub 3}/Ni - 3W substrates. YBCO films with a critical current density J{sub c} of 2.14 times 10{sup 6} A/cm{sup 2} and 1.4 times 10{sup 6} A/cm{sup 2} at 77 K and self-field were grown on the newly developed architectures of Gd{sub 2}Zr{sub 2}O{sub 7}/Y{sub 2}O{sub 3}/Ni - 3W and Zr{sub 1-x}Gd{sub x}O{sub y} (x = 0.2)/Y{sub 2}O{sub 3}/Ni - 3W substrates, respectively using a pulsed laser deposition (PLD) process. This work promises a route for producing cost-effective simplified buffer architectures for the RABiTS-based YBCO coated conductors.

  11. Acetate Transport and Utilization in the Rat Brain

    PubMed Central

    Deelchand, Dinesh K.; Shestov, Alexander A.; Koski, Dee M.; Uğurbil, Kâmil; Henry, Pierre-Gilles

    2009-01-01

    Acetate, a glial-specific substrate, is an attractive alternative to glucose for the study of neuronal-glial interactions. The present study investigates the kinetics of acetate uptake and utilization in the rat brain in vivo during infusion of [2-13C]acetate using NMR spectroscopy. When plasma acetate concentration was increased, the rate of brain acetate utilization (CMRace) increased progressively and reached close to saturation for plasma acetate concentration > 2-3 mM, whereas brain acetate concentration continued to increase. The Michaelis-Menten constant for brain acetate utilization ( KMutil=0.01±0.14mM) was much smaller than for acetate transport through the blood-brain barrier ( KMt=4.18±0.83mM). The maximum transport capacity of acetate through the blood-brain barrier ( Vmaxt=0.96±0.18μmol/g/min) was nearly two-fold higher than the maximum rate of brain acetate utilization ( Vmaxutil=0.50±0.08μmol/g/min). We conclude that, under our experimental conditions, brain acetate utilization is saturated when plasma acetate concentrations increase above 2-3 mM. At such high plasma acetate concentration, the rate-limiting step for glial acetate metabolism is not the blood-brain barrier, but occurs after entry of acetate into the brain. PMID:19393008

  12. Buffer-dependent fragmentation of a humanized full-length monoclonal antibody

    PubMed Central

    Salinas, Branden A; Sathish, Hasige A; Shah, Ambarish U; Carpenter, John F; Randolph, Theodore W

    2014-01-01

    During storage stability studies of a monoclonal antibody (mAb) it was determined that the primary route of degradation involved fragmentation into lower molecular weight species. The fragmentation was characterized with size-exclusion high performance liquid chromatography (SE-HPLC), SDS-PAGE and matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry. Fragmentation proceeded via hydrolysis, likely catalyzed by trace metal ions, of a peptide bond in the hinge region of the mAb’s heavy chain, which produced two prominent low molecular weight species during storage: a single, free Fab fragment and a Fab+Fc fragment. The fragmentation is observed in phosphate-buffered solutions at two ionic strengths but not in histidine-buffered solutions at identical ionic strengths. Chaotrope-induced and thermally-induced unfolding studies of the mAb indicated differences in the unfolding pathways between the two buffer solutions. This folding intermediate observed during chaotrope-induced unfolding was further characterized by intrinsic fluorescence quenching, which suggested that a small portion of the molecule is resistant to chaotrope-induced unfolding in histidine buffer systems. The thermally-induced unfolding indicates a reduction in cooperativity of the unfolding process in the presence of histidine relative to phosphate. A relationship between the histidine-induced effects on unfolding pathway and the relative resistance to fragmentation is suggested. PMID:20091831

  13. 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.

  14. Compatibility of buffered uranium carbides with tungsten.

    NASA Technical Reports Server (NTRS)

    Phillips, W. M.

    1971-01-01

    Results of compatibility tests between tungsten and hyperstoichiometric uranium carbide alloys run at 1800 C for 1000 and 2500 hours. These tests compared tungsten-buffered uranium carbide with tungsten-buffered uranium-zirconium carbide. The zirconium carbide addition appeared to widen the homogeneity range of the uranium carbide, making additional carbon available for reaction. Reaction layers could be formed by either of two diffusion paths, one producing UWC2, while the second resulted in the formation of W2C. UWC2 acts as a diffusion barrier for carbon and slows the growth of the reaction layer with time, while carbon diffusion is relatively rapid in W2C, allowing equilibrium to be reached in less than 2500 hours at a temperature of 1800 C.

  15. 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.

  16. Buffering mechanism for multimedia client applications

    NASA Astrophysics Data System (ADS)

    Tsuda, Yoshiyuki; Nakamura, Akira

    1996-03-01

    In conventional network processing models, a number of data-copies are needed for applications to receive data from network interfaces. This causes major overhead and becomes a serious limitation in distributed multimedia applications. Therefore, several mechanisms have been proposed for reducing the number of data-copies. We emphasize that the Single Virtual address Space (SVS) OS introduces a new buffering mechanisms for this purpose. In this paper, we describe our SVS OS, which we call `Cubix (CUBe of 2-byte unIX)', with a new Access Control List protection mechanism and a new buffering mechanism, which we call `Cstreams (Continuous streams)', based on it. We emphasize that our proposed Cstreams realizes a single data-copy network architecture.

  17. Nuclear Calcium Buffering Capacity Shapes Neuronal Architecture.

    PubMed

    Mauceri, Daniela; Hagenston, Anna M; Schramm, Kathrin; Weiss, Ursula; Bading, Hilmar

    2015-09-18

    Calcium-binding proteins (CaBPs) such as parvalbumin are part of the cellular calcium buffering system that determines intracellular calcium diffusion and influences the spatiotemporal dynamics of calcium signals. In neurons, CaBPs are primarily localized to the cytosol and function, for example, in nerve terminals in short-term synaptic plasticity. However, CaBPs are also expressed in the cell nucleus, suggesting that they modulate nuclear calcium signals, which are key regulators of neuronal gene expression. Here we show that the calcium buffering capacity of the cell nucleus in mouse hippocampal neurons regulates neuronal architecture by modulating the expression levels of VEGFD and the complement factor C1q-c, two nuclear calcium-regulated genes that control dendrite geometry and spine density, respectively. Increasing the levels of nuclear calcium buffers by means of expression of a nuclearly targeted form of parvalbumin fused to mCherry (PV.NLS-mC) led to a reduction in VEGFD expression and, as a result, to a decrease in total dendritic length and complexity. In contrast, mRNA levels of the synapse pruning factor C1q-c were increased in neurons expressing PV.NLS-mC, causing a reduction in the density and size of dendritic spines. Our results establish a close link between nuclear calcium buffering capacity and the transcription of genes that determine neuronal structure. They suggest that the development of cognitive deficits observed in neurological conditions associated with CaBP deregulation may reflect the loss of necessary structural features of dendrites and spines. PMID:26231212

  18. 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.

  19. Buffer Standards for the Physiological pH of the Zwitterionic Compound, ACES from 5 to 55°C.

    PubMed

    Roy, Rabindra N; Roy, Lakshmi N; Fuge, Michael S; Roy, Chandra N; Himes, Curtis A; Bryant, Paul A; Robinson, Kyle T; Kaufmann, Daniel A; Grove, Colby H; Ghosh, Toshi; Bwashi, Adonis

    2009-04-01

    The values of the second dissociation constant pK 2 and related thermodynamic quantities of [N-(2-acetamido)-2-aminoethanesulfonic acid] (ACES) have already been reported over the temperature range 5 to 55°C including 37°C. This paper reports the paH values of four chloride ion free buffer solutions and eight buffer solutions with I = 0.16 mol·kg (-1), matching closely to that of the physiological sample. Conventional paH values for all twelve buffer solutions from 5 to 55°C, are reported. The residual liquid junction potential correction for two widely used temperatures, 25 and 37°C, has been made. The flowing-junction calomel cell method has been utilized to measure Ej , the liquid junction potential. The operational pH values for four buffer solutions at 25 and 37°C are calculated using the physiological phosphate buffer standard based on NBS/NIST convention. These solutions are recommended as pH standards in the pH range of 6.8 to 7.2 for physiological fluids. PMID:20161482

  20. Buffer Standards for the Physiological pH of the Zwitterionic Compound, ACES from 5 to 55°C

    PubMed Central

    Roy, Rabindra N.; Roy, Lakshmi N.; Fuge, Michael S.; Roy, Chandra N.; Himes, Curtis A.; Bryant, Paul A.; Robinson, Kyle T.; Kaufmann, Daniel A.; Grove, Colby H.; Ghosh, Toshi; Bwashi, Adonis

    2009-01-01

    The values of the second dissociation constant pK2 and related thermodynamic quantities of [N-(2-acetamido)-2-aminoethanesulfonic acid] (ACES) have already been reported over the temperature range 5 to 55°C including 37°C. This paper reports the paH values of four chloride ion free buffer solutions and eight buffer solutions with I = 0.16 mol·kg −1, matching closely to that of the physiological sample. Conventional paH values for all twelve buffer solutions from 5 to 55°C, are reported. The residual liquid junction potential correction for two widely used temperatures, 25 and 37°C, has been made. The flowing-junction calomel cell method has been utilized to measure Ej, the liquid junction potential. The operational pH values for four buffer solutions at 25 and 37°C are calculated using the physiological phosphate buffer standard based on NBS/NIST convention. These solutions are recommended as pH standards in the pH range of 6.8 to 7.2 for physiological fluids. PMID:20161482

  1. Online Measurement of the Intramolecular Isotopic Composition of Acetate in Natural Porewater Samples

    NASA Astrophysics Data System (ADS)

    Thomas, R. B.; Arthur, M. A.; Freeman, K. H.

    2006-12-01

    Carbon dioxide and methane are traditionally considered to be the dominant end products of anaerobic metabolism while acetate is thought to be a rapidly consumed intermediate. However, in some settings, recent evidence has grown to suggest that, at least transiently, acetate can be a major metabolic end product. In natural systems, isotopic mass balances can be used to partition the flow of carbon to methane, CO2, and acetate. However, these isotopic estimates require intramolecular measurements of acetate in addition to isotopic measurements of the gaseous species, CO2 and CH4. In practice, the intramolecular isotopic composition of acetate is rarely measured because the analysis is technically challenging and traditionally requires prior separation and offline pyrolysis of purified acetate. As a result of these technical challenges, acetate methyl carbon is usually assumed to be a few permil depleted relative to the carbon isotopic composition of bulk organic matter. In environments where acetate may be produced by autotrophic acetogens this assumption can be devastatingly false. This work describes the use of an online method for the analysis of the intramolecular carbon isotopic composition of dissolved acetate from dilute surface water samples with a detection limit of injected sample down to 500uM. Preconcentration of samples via lyophilization has resulted in detection limits as low as 30uM. In 2002, at Penn State, Dias et al. (Organic Geochemistry Vol. 33, p161-168) reported a technique to examine the intramolecular isotopic composition of acetate from oil-prone source rocks using SPME extraction with an online GC-pyrolysis-IRMS. We have adapted the Dias method to be used with direct injection of dilute natural water samples. Briefly, this procedure protonates acetate with a .1M addition of oxalic acid and vaporizes the sample in the GC inlet at low temperatures. This prevents oxalic acid decomposition and provides sufficient separation of acetate from other volatile acids and water on a polar column (Nukol, Supelco). Following the GC, the acetic acid is reacted with either a combustion furnace (for total acetate) or a pyrolysis furnace for the carboxyl carbon only. The pyrolysis furnace operates at 600°C with Pd wire catalyst and a continuous trickle of H2. The resulting CO2 is then analyzed by conventional IRMS. This GC-PY-IRMS technique is coupled to a GC-C-IRMS such that switching between oxidation and pyrolysis is accomplished by a simple switch followed by a short stabilization period. The above pyrolysis conditions result in a small but characterizable oxidation of methyl carbon to CO2. The cross-contamination of acetate methyl into the acetate carboxyl signal is estimated to be approximately 15 to 20% of the IRMS signal and an isotope dilution series is used to estimate and correct for this contamination. Since this technique is online and allows for the injection of water samples the need for sample extraction and separation are eliminated. This method also significantly improves detection limits over the Dias 2002 method by avoiding SPME injections which have unfavorable partition coefficients for aqueous solutions of acetate.

  2. Acetic acid production from food wastes using yeast and acetic acid bacteria micro-aerobic fermentation.

    PubMed

    Li, Yang; He, Dongwei; Niu, Dongjie; Zhao, Youcai

    2015-05-01

    In this study, yeast and acetic acid bacteria strains were adopted to enhance the ethanol-type fermentation resulting to a volatile fatty acids yield of 30.22 g/L, and improve acetic acid production to 25.88 g/L, with food wastes as substrate. In contrast, only 12.81 g/L acetic acid can be obtained in the absence of strains. The parameters such as pH, oxidation reduction potential and volatile fatty acids were tested and the microbial diversity of different strains and activity of hydrolytic ferment were investigated to reveal the mechanism. The optimum pH and oxidation reduction potential for the acetic acid production were determined to be at 3.0-3.5 and -500 mV, respectively. Yeast can convert organic matters into ethanol, which is used by acetic acid bacteria to convert the organic wastes into acetic acid. The acetic acid thus obtained from food wastes micro-aerobic fermentation liquid could be extracted by distillation to get high-pure acetic acid. PMID:25416587

  3. Acetylation of Starch with Vinyl Acetate in Imidazolium Ionic Liquids and Characterization of Acetate Distribution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch was acetylated with vinyl acetate in different 1-butyl-3-methylimidazolium (BMIM) salts as solvent in effort to produce starches with different acetylation patterns. Overall degree of substitution was much higher for basic anions such as acetate and dicyanimide (dca) than for neutral anions ...

  4. A mammalian acetate switch regulates stress erythropoiesis

    PubMed Central

    Xu, Min; Nagati, Jason S.; Xie, Jian; Li, Jiwen; Walters, Holly; Moon, Young-Ah; Gerard, Robert D.; Huang, Chou-Long; Comerford, Sarah A.; Hammer, Robert E.; Horton, Jay D.; Chen, Rui; Garcia, Joseph A.

    2014-01-01

    Endocrine erythropoietin (Epo), which is synthesized in the kidney or liver of adult mammals, controls erythrocyte production and is regulated by the stress-responsive transcription factor Hypoxia Inducible Factor 2 (HIF-2). We previously reported that the lysine acetyltransferase Cbp is required for HIF-2α acetylation and efficient HIF-2 dependent Epo induction during hypoxia. We now show these processes require acetate-dependent acetyl CoA synthetase 2 (Acss2). In Hep3B hepatoma cells and in Epo-generating organs of hypoxic or acutely anemic mice, acetate levels increase and Acss2 is required for HIF-2α acetylation, Cbp/HIF-2α complex formation and recruitment to the Epo enhancer, and efficient Epo induction. In acutely anemic mice, acetate supplementation augments stress erythropoiesis in an Acss2-dependent manner. In acquired and genetic chronic anemia mouse models, acetate supplementation also increases Epo expression and resting hematocrits. Thus, a mammalian stress-responsive acetate switch controls HIF-2 signaling and Epo induction during pathophysiological states marked by tissue hypoxia. PMID:25108527

  5. EXTRACTION AND ELECTROSPINNING OF ZEIN EXTRACTED FROM CORN GLUTEN MEAL USING ACETIC ACID

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been demonstrated that zein fibers can be produced using the electrospinning technique. Fibers electrospun from acetic acid solution under suitable conditions provide fibers with a more consistent morphology (round 0.5-2.0 micro fibers) compared to fibers produced from aqueous ethanol soluti...

  6. Formation of biologically relevant carboxylic acids during the gamma irradiation of acetic acid

    NASA Technical Reports Server (NTRS)

    Negron-Mendoza, A.; Ponnamperuma, C.

    1976-01-01

    Irradiation of aqueous solutions of acetic acid with gamma rays produced several carboxylic acids in small yield. Their identification was based on the technique of gas chromatography combined with mass spectrometry. Some of these acids are Krebs Cycle intermediates. Their simultaneous formation in experiments simulating the primitive conditions on the earth suggests that metabolic pathways may have had their origin in prebiotic chemical processes.

  7. A fast data-bus to buffer-memory interface

    NASA Astrophysics Data System (ADS)

    Vander Molen, A.; Maier, M. R.; Robertson, M.; Westfall, G. D.

    1991-09-01

    A fast, economical VME based interface between fast data buses and high speed buffer memories has been built. This module in addition to handling the hand-shaking lines, supplies a gate, a busy signal, and a clear signal at the end of data transfer. A header word with programmable contents is inserted at the beginning of each event giving a discernable event boundary. This device, dubbed the FERA Faucet Maier (FFM), has been applied to the LeCroy ECLine bus coupled to a Creative Electronics Solution 8170 High Speed Memory. It will transfer data at rates up to 10 Mbytes/s from the LeCroy FERAs to the VME based memory.

  8. Adsorptive Membranes vs. Resins for Acetic Acid Removal from Biomass Hydrolysates

    SciTech Connect

    Han, B.; Carvalho, W.; Canilha, L.; da Silva, S. S.; e Silva, J. B. A.; McMillan, J. D.; Wickramasinghe, S. R.

    2006-01-01

    Acetic acid is a compound commonly found in hemicellulosic hydrolysates. This weak acid strongly influences the bioconversion of sugar containing hydrolysates. Previous investigators have used anion exchange resins for acetic acid removal from different hemicellulosic hydrolysates. In this study, the efficiency of an anion exchange membrane was compared to that of an anion exchange resin, for acetic acid removal from a DI water solution and an acidic hemicellulose hydrolysate pretreated using two different methods. Ion exchange membranes and resins have very different geometries. Here the performance of membranes and resins is compared using two dimensionless parameters, the relative mass throughput and chromatographic bed number. The relative mass throughput arises naturally from the Thomas solution for ion exchange. The results show that the membrane exhibit better performance in terms of capacity, and loss of the desired sugars. In addition acetic acid may be eluted at a higher concentration from the membrane thus leading to the possibility of recovery and re-use of the acetic acid.

  9. META-ANALYSIS OF NITROGEN REMOVAL IN RIPARIAN BUFFERS

    EPA Science Inventory

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

  10. Hormetic effect of ionic liquid 1-ethyl-3-methylimidazolium acetate on bacteria

    DOE PAGESBeta

    Nancharaiah, Y. V.; Francis, A. J.

    2015-02-19

    The biological effect of ionic liquids (ILs) is one of the highly debated topics as they are being contemplated for various industrial applications. 1-ethyl-2-methylimidazolium acetate ([EMIM][Ac]) showed remarkable hormesis on anaerobic Clostridium sp. and aerobic Psueudomonas putida. Bacterial growth was stimulated at up to 2.5 g L-1 and inhibited at > 2.5 g L-1 of ([EMIM][Ac]). The growth of Clostridium sp. and P. putida were higher by 0.4 and 4-fold respectively, in the presense of 0.5 g L-1 of ([EMIM][Ac]). Assessment of the effect of [EMIM][Ac] under different growth conditions showed that the hormesis of [EMIM][Ac] was mediated via regulationmore » of medium pH. Hormetic effect of [EMIM][Ac] was evident only in medium with poor buffering capacity and in the presence of a fermentable substrate as the carbon source. The hormetic effect of [EMIM][Ac] on bacterial growth is most likely associated with the buffering capacity of acetate anion. These observations have implications in ILs toxicity studies and ecological risk assessment.« less

  11. Hormetic effect of ionic liquid 1-ethyl-3-methylimidazolium acetate on bacteria

    SciTech Connect

    Nancharaiah, Y. V.; Francis, A. J.

    2015-02-19

    The biological effect of ionic liquids (ILs) is one of the highly debated topics as they are being contemplated for various industrial applications. 1-ethyl-2-methylimidazolium acetate ([EMIM][Ac]) showed remarkable hormesis on anaerobic Clostridium sp. and aerobic Psueudomonas putida. Bacterial growth was stimulated at up to 2.5 g L-1 and inhibited at > 2.5 g L-1 of ([EMIM][Ac]). The growth of Clostridium sp. and P. putida were higher by 0.4 and 4-fold respectively, in the presense of 0.5 g L-1 of ([EMIM][Ac]). Assessment of the effect of [EMIM][Ac] under different growth conditions showed that the hormesis of [EMIM][Ac] was mediated via regulation of medium pH. Hormetic effect of [EMIM][Ac] was evident only in medium with poor buffering capacity and in the presence of a fermentable substrate as the carbon source. The hormetic effect of [EMIM][Ac] on bacterial growth is most likely associated with the buffering capacity of acetate anion. These observations have implications in ILs toxicity studies and ecological risk assessment.

  12. Platelet additive solutions: a future perspective.

    PubMed

    van der Meer, P F

    2007-12-01

    Platelet additive solutions (PASs) were first developed in the 1980s, and continued to be improved over the following years. The use of PASs as replacement for plasma has a number of benefits, both for the quality of the platelet concentrates and for the patients. However, some PASs have been associated with a lower platelet yield in the PCs, a shorter storage time, and a lower increment in the patient when compared to PCs in plasma. A number of reformulations of the PASs have taken place to counteract these disadvantages. Most PASs use acetate as nutrient for the platelets, which has the benefit of generating bicarbonate when oxidized by the platelets, thus supplying its own buffering capacity. Alternatively, glucose is used, but may cause deterioration of pH in the stored PCs due to the formation of lactic acid. Addition of other buffering substances, such as phosphate, can be added to ensure maintenance of neutral pH. An important finding was the inhibiting effect of potassium and magnesium on platelet activation. The initially developed PASs lacked these two ingredients and showed reduced storage times of the PCs in PAS when compared to those stored in plasma. However, when these constituents are included in the PAS, storage time is similar and even exceeds those seen for PCs in plasma. Considerable research is done in further formulating the optimal PAS. Bicarbonate is being considered as buffer for these PASs. Also, L-carnitine appears to have a favorable effect on stored platelets, including a reduction of platelet metabolism, and inhibition of apoptosis. Another area of optimization is lowering of plasma content needed for maintaining platelet quality. Where current PASs still need at least 30% residual plasma, there is a trend towards lowering the plasma content to less than 5% with the newer PASs. Preservation of purinergic platelet receptor functionality by ADP-degrading activities in plasma appears to play an important role in this respect. Development of PASs are usually based on in vitro studies alone. It is important to realize that only clinical studies can give definitive answers about the quality of platelets stored in PASs. Sofar, only limited clinical evaluations have been published that either studied the effectiveness of platelets in initially-developed PASs, or were specifically done in combination with pathogen reduction technologies. Thus, PASs seem to be an excellent replacement for (part of) the plasma when producing PCs, and allow extended storage with maintenance of quality, but more clinical studies are needed to substantiate in vitro results. PMID:18420439

  13. Dynamic Protonation Equilibrium of Solvated Acetic Acid

    SciTech Connect

    Gu, Wei; Frigato, Tomaso; Straatsma, TP; Helms, Volkhard H.

    2007-04-13

    For the first time, the dynamic protonation equilibrium between an amino acid side chain analogue and bulk water as well as the diffusion properties of the excess proton were successfully reproduced through unbiased computer simulations. During a 50 ns Q-HOP MD simulation, two different regimes of proton transfer were observed. Extended phases of frequent proton swapping between acetic acid and nearby water were separated by phases where the proton freely diffuses in the simulation box until it is captured again by acetic acid. The pKa of acetic acid was calculated around 3.0 based on the relative population of protonated and deprotonated states and the diffusion coefficient of excess proton was computed from the average mean squared displacement in the simulation. Both calculated values agree well with the experimental measurements.

  14. Enhanced dielectric properties from barium strontium titanate films with strontium titanate buffer layers

    NASA Astrophysics Data System (ADS)

    Cole, M. W.; Ngo, E.; Hubbard, C.; Hirsch, S. G.; Ivill, M.; Sarney, W. L.; Zhang, J.; Alpay, S. P.

    2013-10-01

    In order to enhance the permittivity and tunability of the dielectric component, a thin film dielectric composite consisting of a radio frequency sputtered SrTiO3 (STO) buffer layer and metalorganic solution deposited Mg-doped BaxSr1-xTiO3 (Mg-BST) thin film overgrowth was developed using affordable industry standard processes and materials. The effect of the STO buffer layer thickness on the dielectric response of the heterostructure was investigated. Our results demonstrate that the composite film heterostructure, evaluated in the metal-insulator-metal configuration Pt/STO/Mg-BST/Pt on sapphire substrate, with the thinner (9-17 nm) STO buffer layers possessed enhanced permittivity (?r 491) with respect to the thicker 41 nm buffer layer (?r 360) and that of a control Mg-BST film without a STO buffer layer (?r 380). Additionally, the composite film with the thinner buffer layers were shown to have low losses (tan ? 0.02), low leakage characteristics (J = 7.0 10-9 A/cm2), high breakdown voltage (VBR > 10 V), a large grain microstructure (125 nm), and smooth pin-hole free surfaces. The enhanced permittivity of the composite dielectric film resulted from three major factors: (i) the template-effect of the thin STO buffer layer on the thicker Mg-BST over-layer film to achieve a large grain microstructure, (ii) the low viscosity of the metallo-organic solution deposition (MOSD) solution, which ensured heterogeneous nucleation of the Mg-BST overgrowth film on the surface of the STO buffer layer, and (iii) minimization of the low permittivity grain boundary phase (TiO2-x phase). The dielectric response of the BST can be explained using a thermodynamic model taking into account interlayer electrostatic and electromechanical interactions. Additionally, Mg doping of the BST enabled low loss and low leakage characteristics of the heterostructure. The large permittivity, low loss, low leakage characteristics, and defect free surfaces of the composite dielectric heterostructure promote tunable device miniaturization and hold the potential to enable enhanced electromagnetic coupling in ferromagnetic/high permittivity dielectric heterostructures, which in turn would facilitate the realization of integrated charge mediated voltage controlled magnetic radio frequency/microwave communication devices.

  15. Determination of Unknown Concentrations of Sodium Acetate Using the Method of Standard Addition and Proton NMR: An Experiment for the Undergraduate Analytical Chemistry Laboratory

    ERIC Educational Resources Information Center

    Rajabzadeh, Massy

    2012-01-01

    In this experiment, students learn how to find the unknown concentration of sodium acetate using both the graphical treatment of standard addition and the standard addition equation. In the graphical treatment of standard addition, the peak area of the methyl peak in each of the sodium acetate standard solutions is found by integration using…

  16. Physicochemical interactions of the isomers of aminobenzoic acid with sodium acetate in solid-matrix room-temperature luminescence spectroscopy

    SciTech Connect

    Ramasamy, S.M.; Hurtubise, R.J. )

    1990-01-01

    The room-temperature fluorescence and room-temperature phosphorescence quantum yields of the isomers of aminobenzoic acid adsorbed on sodium acetate were obtained. These data were correlated with solution fluorescence data and diffuse reflectance infrared spectral data from the three isomers. The results yielded insights into the bonding interactions of the aminobenzoic acid isomers with sodium acetate. In particular, the specific structural and bonding characteristics of the isomers with sodium acetate were very important in determining whether a high room-temperature phosphorescence quantum yield would be obtained from a given isomer.

  17. Optimized DPPH assay in a detergent-based buffer system for measuring antioxidant activity of proteins

    PubMed Central

    Nicklisch, Sascha C.T.; Waite, J. Herbert

    2014-01-01

    The free radical method using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) is a well established assay for the in vitro determination of antioxidant activity in food and biological extracts. The standard DPPH assay uses methanol or ethanol as solvents, or buffered alcoholic solutions in a ratio of 40%/60% (buffer/alcohol, v/v) to keep the hydrophobic hydrazyl radical and phenolic test compounds soluble while offering sufficient buffering capacity at different pHs tested. Following this protocol, we were unable to keep proteinaceous antioxidants soluble at different pHs to test for their antioxidant activity. Thus, the assay protocol was modified as follows to improve its utility:•Non-ionic detergents were added to keep the DPPH radical soluble and to provide a mild and non-denaturing environment for the antioxidant protein.•Maximal concentration of DPPH was limited to 100 μM to stay within the sensitivity range of the detector at the given wavelength (515 nm) and to increase the dynamic range of the assay.•0.1 M citrate phosphate buffer was introduced to prevent experimental artifacts due to changing buffer compositions at different pHs. PMID:25530949

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

    SciTech Connect

    Jayaweera, P.; Hettiarachchi, S.

    1994-03-01

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

  19. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

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

  20. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

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

  1. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

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

  2. 43 CFR 3931.100 - Boundary pillars and buffer zones.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Groundwater nitrate following installation of a vegetated riparian buffer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Buffers are often planted along streams to reduce nutrient loss from fields. The purpose of this study was to determine if a vegetated buffer could significantly decrease groundwater nitrate-nitrogen (NO3) concentrations. During 2000 and 2001, a three-part buffer was planted adjacent to a first-ord...

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

    DOEpatents

    Kruger, H.W.

    1994-05-10

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

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

    DOEpatents

    Kruger, Hans W.

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

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

  8. Analysis of a hybrid, unidirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  9. Analysis of a hybrid-undirectional buffer strip laminate

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  10. Buffer layers and articles for electronic devices

    DOEpatents

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

    2004-07-20

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

  11. Spacecraft optical disk recorder memory buffer control

    NASA Technical Reports Server (NTRS)

    Hodson, Robert F.

    1992-01-01

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

  12. Buffer Standards for the Biological pH of the Amino Acid N-[2 hydroxyethyl]piperazine-N’-[3-propanesulfonic acid], HEPPS, From (278.15 to 328.15) K

    PubMed Central

    Roy, Lakshmi N.; Roy, Rabindra N.; Wollen, Joshua T.; Harmon, Meagan A.; Stegner, Jessica M.; Shah, Ankita A.; Henson, Isaac B.

    2011-01-01

    For the HEPPS buffer under investigation, there are seven buffer solutions without NaCl and eight buffer solutions that contain Cl− and have an ionic strength (I = 0.16 mol·kg−1), which is similar to that of blood plasma. These buffer solutions have been evaluated in the temperature range of (278.15 to 328.15) K using the extended Debye- Hückel equation and the Bates-Guggenheim convention. The previously determined Ej values have been used to determine the operational pH values of HEPPS buffer solutions at (298.15 and 310.15) K. These are recommended as secondary standard reference solutions for pH measurements in saline media with an isotonic ionic strength of I = 0.16 mol·kg−1. PMID:22096257

  13. Synthesis of Cellulose Acetate from Cotton Byproducts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton burr and cottonseed hull are relatively inexpensive cotton byproducts. In an effort to derive greater value out of these natural renewable materials, we have succeeded in converting part of them into cellulose acetate without prior chemical breakdown or physical separation of cellulose, ligni...

  14. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium acetate. 184.1185 Section 184.1185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS §...

  15. Advanced Colloids Experiment (ACE-T1)

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Sicker, Ron; Brown, Dan; Eustace, John

    2015-01-01

    Increment 45 - 46 Science Symposium presentation of Advanced Colloids Experiment (ACE-T1) to RPO. The purpose of this event is for Principal Investigators to present their science objectives, testing approach, and measurement methods to agency scientists, managers, and other investigators.

  16. 21 CFR 173.228 - Ethyl acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethyl acetate. 173.228 Section 173.228 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Solvents, Lubricants, Release Agents and...

  17. 21 CFR 173.228 - Ethyl acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethyl acetate. 173.228 Section 173.228 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Solvents, Lubricants, Release Agents and...

  18. 21 CFR 173.228 - Ethyl acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethyl acetate. 173.228 Section 173.228 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Solvents, Lubricants, Release Agents and...

  19. 21 CFR 173.228 - Ethyl acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethyl acetate. 173.228 Section 173.228 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Solvents, Lubricants, Release Agents and...

  20. Process for the preparation of vinyl acetate

    DOEpatents

    Tustin, Gerald Charles (Kingsport, TN); Zoeller, Joseph Robert (Kingsport, TN); Depew, Leslie Sharon (Kingsport, TN)

    1998-01-01

    This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at about one bar pressure and between about 85.degree. and 200.degree. C. and removing the reaction products from the contact zone.

  1. 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 Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS §...

  2. 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, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives §...

  3. Heat Bonding of Irradiated Ethylene Vinyl Acetate

    NASA Technical Reports Server (NTRS)

    Slack, D. H.

    1986-01-01

    Reliable method now available for joining parts of this difficult-tobond material. Heating fixture encircles ethylene vinyl acetate multiplesocket part, providing heat to it and to tubes inserted in it. Fixtures specially designed to match parts to be bonded. Tube-and-socket bonds made with this technique subjected to tensile tests. Bond strengths of 50 percent that of base material obtained consistently.

  4. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium acetate. 184.1185 Section 184.1185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  5. 21 CFR 184.1185 - Calcium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium acetate. 184.1185 Section 184.1185 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  6. Process for the preparation of vinyl acetate

    DOEpatents

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

    1998-02-17

    This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at about one bar pressure and between about 85 and 200 C and removing the reaction products from the contact zone.

  7. 21 CFR 522.533 - Deslorelin acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Deslorelin acetate. 522.533 Section 522.533 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 DRUGS §...

  8. 21 CFR 556.380 - Melengestrol acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Melengestrol acetate. 556.380 Section 556.380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD...

  9. 21 CFR 556.380 - Melengestrol acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Melengestrol acetate. 556.380 Section 556.380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD...

  10. Contraction of rat thoracic aorta strips induced by phorbol 12-myristate 13-acetate

    SciTech Connect

    Itoh, H.; Lederis, K.

    1987-02-01

    Phorbol 12-myristate 13-acetate (PMA) induced a slow and progressive increase in tension of rat thoracic aorta strips in the presence of extracellular CaS . Complete relaxation could not be obtained in CaS -free buffer containing 1 mM ethyleneglycol-bis(US -aminoethylether)-N,N'-tetraacetic acid (EGTA) and 10 X M PMA. In the absence of extracellular CaS , PMA (10 X M) induced a small but sustained contraction which was not altered by the addition of another 2 mM EGTA and 3 x 10 V M verapamil. Papaverine (10 U M) relaxed the PMA-induced contraction to the base line, but phentolamine (10 V M), cyproheptadine (10 V M), atropine (10 V M) and tetrodotoxine (10 W M) did not change the contraction. CaS -depleted muscle strips, prepared by four repeated applications of 10 X M norepinephrine in CaS -free buffer, were contracted by 10 X M PMA, but at a lower maximum tension than nontreated strips. The action of PMA on rat aorta strips in CaS -free buffer did not require the presence of the adventitial layer or endothelial cells. These results suggest that PMA may induce activation of protein kinase C and smooth muscle contraction in the absence of extracellular CaS , without an increase in myoplasmic CaS .

  11. Cs vapor microcells with Ne-He buffer gas mixture for high operation-temperature miniature atomic clocks.

    PubMed

    Kroemer, E; Abdel Hafiz, M; Maurice, V; Fouilland, B; Gorecki, C; Boudot, R

    2015-07-13

    We report on the characterization of Cs vapor microfabricated cells filled with a Ne-He buffer gas mixture using coherent population trapping (CPT) spectroscopy. The temperature dependence of the Cs clock frequency is found to be canceled at the first order around a so-called inversion temperature higher than 80°C whose value depends on the buffer gas partial pressure ratio. This buffer gas mixture could be well-adapted for the development of miniature atomic clocks devoted to be used in specific applications such as defense and avionic systems with high operating temperature environment (typically higher than 85°C). This solution suggests an alternative to buffer gas mixtures generally used in optically-pumped vapor cell atomic clocks. PMID:26191895

  12. Modification of gel architecture and TBE/TAE buffer composition to minimize heating during agarose gel electrophoresis

    PubMed Central

    Sanderson, Brian A.; Araki, Naoko; Lilley, Jennifer L.; Guerrero, Gilberto; Lewis, L. Kevin

    2014-01-01

    Agarose gel electrophoresis of DNA and RNA is routinely performed using buffers containing either Tris, acetate and EDTA (TAE) or Tris, borate and EDTA (TBE). Gels are run at a low, constant voltage (~ 10 V/cm) to minimize current and asymmetric heating effects, which can induce band artifacts and poor resolution. In this study, alterations of gel structure and conductive media composition were analyzed to identify factors causing higher electrical currents during horizontal slab gel electrophoresis. Current was reduced when thinner gels and smaller chamber buffer volumes were used, but was not influenced by agarose concentration or the presence of ethidium bromide. Current was strongly dependent upon the amount and type of EDTA used and on the concentrations of the major acid-base components of each buffer. Interestingly, resolution and the mobilities of circular versus linear plasmid DNAs were also affected by the chemical form and amount of EDTA. With appropriate modifications to gel structure and buffer constituents, electrophoresis could be performed at high voltages (20–25 V/cm), reducing run times by up to 3-fold. The most striking improvements were observed with small DNAs and RNAs (10 – 100 bp): high voltages and short run times produced sharper bands and higher resolution. PMID:24637158

  13. Alignment of microcrystals of manganese-12-acetate and direct observation of single molecules thereof

    NASA Astrophysics Data System (ADS)

    Seo, Dongmin

    This dissertation focuses on three separate studies. First, magnetization of the Mn12-acetate was studied by low temperature hysteresis loops and DC magnetization data on magnetically aligned Mn12-acetate micro-crystals. Secondly, Mn12-acetate thin films were fabricated and characterized by AFM and STM. Finally, magnetization of the film material was also studied. Enhanced alignment of Mn12-acetate micro-crystals as compared to prior studies was verified by observation of several sharp steps in low temperature hysteresis loops. It was found that ˜0.5 T is sufficient to orient the micro-crystals in an organic solvent to a degree comparable to a single crystal. The degree of the alignment was controlled by varying the magnetic field at room temperature and during the cooling process. Subsequently, low temperature hysteresis loops and DC magnetizations were measured for each prepared orientation state of a sample. The high temperature magnetic anisotropy responsible for the alignment could not be measured, possibly due to its small magnitude. Mn12-acetate was deposited onto Si/SiO2 by a solution evaporation method. Atomic force microscopy studies revealed that 2 nm thick films of molecular level smoothness were formed. Mn12-acetate was also deposited onto a Highly Ordered Pyrolytic Graphite (HOPG) surface for scanning tunneling microscopy (STM) studies. A self-assembled triangular lattice was observed in the Mn12-acetate thin films by STM at room temperature under ambient conditions. These STM images show typical center to center intermolecular separations of about 6.3 nm and height corrugation of less than 0.5 nm. Magnetization measurements were not successful in Mn12-acetate thin films due to the small amount of material in the film and the large background signal from the substrate. Therefore, a sample for the magnetization measurements, called "film material", was made by evaporating a dilute solution of Mn12-acetate powder in acetonitrile. Significant changes in magnetic properties of the film material were observed from magnetization measurements. The blocking temperature of the film material was found to increase to TB > 10 K at low magnetic fields.

  14. Facile pulping of lignocellulosic biomass using choline acetate.

    PubMed

    Cheng, Fangchao; Wang, Hui; Chatel, Gregory; Gurau, Gabriela; Rogers, Robin D

    2014-07-01

    Treating ground bagasse or Southern yellow pine in the biodegradable ionic liquid (IL), choline acetate ([Cho][OAc]), at 100°C for 24h led to dissolution of hemicellulose and lignin, while leaving the cellulose pulp undissolved, with a 54.3% (bagasse) or 34.3% (pine) reduction in lignin content. The IL solution of the dissolved biopolymers can be separated from the undissolved particles either by addition of water (20 wt% of IL) followed by filtration or by centrifugation. Hemicellulose (19.0 wt% of original bagasse, 10.2 wt% of original pine, containing 14-18 wt% lignin) and lignin (5.0 wt% of original bagasse, 6.0 wt% of original pine) could be subsequently precipitated. The pulp obtained from [Cho][OAc] treatment can be rapidly dissolved in 1-ethyl-3-methylimidazolium acetate (e.g., 17 h for raw bagasse vs. 7h for pulp), and precipitated as cellulose-rich material (CRM) with a lower lignin content (e.g., 23.6% for raw bagasse vs. 10.6% for CRM). PMID:24874879

  15. Synthesis and characterization of cellulose acetate from rice husk: eco-friendly condition.

    PubMed

    Das, Archana M; Ali, Abdul A; Hazarika, Manash P

    2014-11-01

    Cellulose acetate was synthesized from rice husk by using a simple, efficient, cost-effective and solvent-free method. Cellulose was isolated from rice husk (RH) using standard pretreatment method with dilute alkaline and acid solutions and bleaching with 2% H2O2. Cellulose acetate (CA) was synthesized successfully with the yield of 66% in presence of acetic anhydride and iodine as a catalyst in eco-friendly solvent-free conditions. The reaction parameters were standardized at 80 °C for 300 min and the optimum results were taken for further study. The extent of acetylation was evaluated from % yield and the degree of substitution (DS), which was determined by (1)H NMR and titrimetrically. The synthesized products were characterized with the help modern analytical techniques like FT-IR, (1)H NMR, XRD, etc. and the thermal behavior was evaluated by TGA and DSC thermograms. PMID:25129753

  16. Phenyl Acetate Preparation from Phenol and Acetic Acid: Reassessment of a Common Textbook Misconception.

    ERIC Educational Resources Information Center

    Hocking, M. B.

    1980-01-01

    Reassesses a common textbook misconception that "...phenols cannot be esterified directly." Results of experiments are discussed and data tables provided of an effective method for the direct preparation of phenyl acetate. (CS)

  17. Influence of bicarbonate buffer on the methanogenetic pathway during thermophilic anaerobic digestion.

    PubMed

    Lin, Yucheng; Lü, Fan; Shao, Liming; He, Pinjing

    2013-06-01

    To investigate the influence of bicarbonate on the metabolic pathway of methanogenesis, different concentrations of bicarbonate (0-0.2 mol/L) were applied during thermophilic anaerobic digestion of 2.5 and 5 g/L glucose. The stable carbon isotopic results demonstrated that, as the bicarbonate concentration increased, the proportion of total CH4 generated from hydrogenotrophic methanogenesis generally increased. Furthermore, methane production rates and acetate degradation rates were seriously reduced under high levels of bicarbonate (0.15 and 0.2 mol/L). Meanwhile, carbon isotope fractionation was more prominent in treatments with 5 g/L glucose than that of 2.5 g/L glucose. Increased concentrations of bicarbonate altered the dominant methanogens and bacteria and increased the microbial diversity. The inhibitory effects of high concentrations of bicarbonate suggested that bicarbonate should be used cautiously as a buffer salt in anaerobic processes, especially when methanogenetic pathways were studied. PMID:23587826

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

    NASA Astrophysics Data System (ADS)

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

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

  19. Energetics and structure of uranium(VI)-acetate complexes in dimethyl sulfoxide.

    PubMed

    Di Bernardo, Plinio; Zanonato, Pier Luigi; Benetollo, Franco; Melchior, Andrea; Tolazzi, Marilena; Rao, Linfeng

    2012-08-20

    The thermodynamics of the complexation between uranium(VI) and acetate in dimethyl sulfoxide (DMSO) was studied at 298 K in an ionic medium of 0.1 mol dm(-3) tetrabutyl ammonium perchlorate. The results show that the uranyl ion forms three strong successive mononuclear complexes with acetate. The complexes, both enthalpically and entropically stabilized, are significantly more stable in DMSO than in water. This feature can be ascribed to the weak solvation of acetate in DMSO. The thermodynamic parameters for the formation of the uranium(VI) complexes with acetate in DMSO are compared with those with ethylenediamine in the same solvent. The difference between the two ligand systems reveals that, for the complexation reactions involving charge neutralization, the reorganization of the solvent gives a very important contribution to the overall complexation energetics. The coordination mode of acetate in the uranyl complexes and the changes of the solvation sphere of UO(2)(2+) upon complexation were investigated by FT-IR spectroscopy in DMSO and in acetonitrile/DMSO mixtures. In addition, DFT calculations were performed to provide an accurate description of the complexation at the molecular level. The experimental and calculated results suggest that acetate is solely bidentate to UO(2)(2+) in the 1:1 and 1:3 complexes but mono- and bidentate in the 1:2 complexes. The DFT calculations also indicate that the medium effects must always be taken into account in order to gain accurate information on the complex formation in solution. In fact, the relative stability of the reaction products changes markedly when the DFT calculations are carried out in vacuum or in DMSO solution. PMID:22870864

  20. Acetic acid detection threshold in synthetic wine samples of a portable electronic nose.

    PubMed

    Macas, Miguel Macas; Manso, Antonio Garca; Orellana, Carlos Javier Garca; Velasco, Horacio Manuel Gonzlez; Caballero, Ramn Gallardo; Chamizo, Juan Carlos Peguero

    2013-01-01

    Wine quality is related to its intrinsic visual, taste, or aroma characteristics and is reflected in the price paid for that wine. One of the most important wine faults is the excessive concentration of acetic acid which can cause a wine to take on vinegar aromas and reduce its varietal character. Thereby it is very important for the wine industry to have methods, like electronic noses, for real-time monitoring the excessive concentration of acetic acid in wines. However, aroma characterization of alcoholic beverages with sensor array electronic noses is a difficult challenge due to the masking effect of ethanol. In this work, in order to detect the presence of acetic acid in synthetic wine samples (aqueous ethanol solution at 10% v/v) we use a detection unit which consists of a commercial electronic nose and a HSS32 auto sampler, in combination with a neural network classifier (MLP). To find the characteristic vector representative of the sample that we want to classify, first we select the sensors, and the section of the sensors response curves, where the probability of detecting the presence of acetic acid will be higher, and then we apply Principal Component Analysis (PCA) such that each sensor response curve is represented by the coefficients of its first principal components. Results show that the PEN3 electronic nose is able to detect and discriminate wine samples doped with acetic acid in concentrations equal or greater than 2 g/L. PMID:23262483

  1. Acetic Acid Detection Threshold in Synthetic Wine Samples of a Portable Electronic Nose

    PubMed Central

    Macías, Miguel Macías; Manso, Antonio García; Orellana, Carlos Javier García; Velasco, Horacio Manuel González; Caballero, Ramón Gallardo; Chamizo, Juan Carlos Peguero

    2013-01-01

    Wine quality is related to its intrinsic visual, taste, or aroma characteristics and is reflected in the price paid for that wine. One of the most important wine faults is the excessive concentration of acetic acid which can cause a wine to take on vinegar aromas and reduce its varietal character. Thereby it is very important for the wine industry to have methods, like electronic noses, for real-time monitoring the excessive concentration of acetic acid in wines. However, aroma characterization of alcoholic beverages with sensor array electronic noses is a difficult challenge due to the masking effect of ethanol. In this work, in order to detect the presence of acetic acid in synthetic wine samples (aqueous ethanol solution at 10% v/v) we use a detection unit which consists of a commercial electronic nose and a HSS32 auto sampler, in combination with a neural network classifier (MLP). To find the characteristic vector representative of the sample that we want to classify, first we select the sensors, and the section of the sensors response curves, where the probability of detecting the presence of acetic acid will be higher, and then we apply Principal Component Analysis (PCA) such that each sensor response curve is represented by the coefficients of its first principal components. Results show that the PEN3 electronic nose is able to detect and discriminate wine samples doped with acetic acid in concentrations equal or greater than 2 g/L. PMID:23262483

  2. Near-surface ion distribution and buffer effects during electrochemical reactions.

    PubMed

    Auinger, Michael; Katsounaros, Ioannis; Meier, Josef C; Klemm, Sebastian O; Biedermann, P Ulrich; Topalov, Angel A; Rohwerder, Michael; Mayrhofer, Karl J J

    2011-09-28

    The near-surface ion distribution at the solid-liquid interface during the Hydrogen Oxidation Reaction (HOR)/Hydrogen Evolution Reaction (HER) on a rotating platinum disc electrode is demonstrated in this work. The relation between reaction rate, mass transport and the resulting surface pH-value is used to theoretically predict cyclic voltammetry behaviour using only thermodynamic and diffusion data obtained from the literature, which were confirmed by experimental measurements. The effect of buffer addition on the current signal, the surface pH and the ion distribution is quantitatively described by analytical solutions and the fragility of the surface pH during reactions that form or consume H(+) in near-neutral unbuffered solutions or poorly buffered media is highlighted. While the ideal conditions utilized in this fundamental study cannot be directly applied to real scenarios, they do provide a basic understanding of the surface pH concept for more complex heterogeneous reactions. PMID:21837326

  3. Kinetics of an acid-base catalyzed reaction (aspartame degradation) as affected by polyol-induced changes in buffer pH and pK values.

    PubMed

    Chuy, S; Bell, L N

    2009-01-01

    The kinetics of an acid-base catalyzed reaction, aspartame degradation, were examined as affected by the changes in pH and pK(a) values caused by adding polyols (sucrose, glycerol) to phosphate buffer. Sucrose-containing phosphate buffer solutions had a lower pH than that of phosphate buffer alone, which contributed, in part, to reduced aspartame reactivity. A kinetic model was introduced for aspartame degradation that encompassed pH and buffer salt concentrations, both of which change with a shift in the apparent pK(a) value. Aspartame degradation rate constants in sucrose-containing solutions were successfully predicted using this model when corrections (that is, lower pH, lower apparent pK(a) value, buffer dilution from the polyol) were applied. The change in buffer properties (pH, pK(a)) from adding sucrose to phosphate buffer does impact food chemical stability. These effects can be successfully incorporated into predictive kinetic models. Therefore, pH and pK(a) changes from adding polyols to buffer should be considered during food product development. PMID:19200086

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

    NASA Technical Reports Server (NTRS)

    Kennedy, John M.

    1990-01-01

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

  5. Studies of Solution Deposited Cerium Oxide Thin Films on Textured Ni-Alloy Substractes for YBCO Superconductor

    SciTech Connect

    Stewart, Erin L; Bhuiyan, Md S; Sathyamurthy, Srivatsan; Paranthaman, Mariappan Parans

    2006-01-01

    Cerium oxide (CeO2) buffer layers play an important role for the development of YBa2Cu3O7-x (YBCO) based superconducting tapes using the rolling assisted biaxially textured substrates (RABiTS) approach. The chemical solution deposition (CSD) approach has been used to grow epitaxial CeO2 films on textured Ni-3 a 4% W alloy substrates with various starting precursors of ceria. Precursors such as cerium acetate, cerium acetylacetonate, cerium 2-ethylhexanoate, cerium nitrate, and cerium trifluoroacetate were prepared in suitable solvents. The optimum growth conditions for these cerium precursors were Ar-4% H2 gas processing atmosphere, solution concentration levels of 0.2-0.5 M, a dwell time of 15 min, and a process temperature range of 1050-1150 degrees C. X-ray diffraction, AFM, SEM, and optical microscopy were used to characterize the CeO2 films. Highly textured CeO2 layers were obtained on Ni-W substrates with both cerium acetate and cerium acetylacetonate as starting precursors. YBCO films with a Jc of 1.5 MA/cm2 were obtained on cerium acetylacetonate-based CeO2 films with sputtered YSZ and CeO2 cap layers.

  6. 21 CFR 582.5892 - a-Tocopherol acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5892 a-Tocopherol acetate. (a) Product. a-Tocopherol acetate. (b) Conditions of use....

  7. 21 CFR 582.5892 - a-Tocopherol acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 582.5892 a-Tocopherol acetate. (a) Product. a-Tocopherol acetate. (b) Conditions of use....

  8. Method of making a cellulose acetate low density microcellular foam

    DOEpatents

    Rinde, James A.

    1978-01-01

    Low-density microcellular foam having a cell size of not greater than 2 .mu.m and method of making by dissolving cellulose acetate in an acetone-based solvent, gelling the solution in a water bath maintained at 0-10.degree. C for a selected period of time to allow impurities to diffuse out, freezing the gel, and then freeze-drying wherein water and solvents sublime and the gel structure solidifies into low-density microcellular foam. The foam has a density of 0.065 to 0.6.times.10.sup.3 kg/m.sup.3 and cell size of about 0.3 to 2 .mu.m. The small cell size foam is particularly adaptable for encapsulation of laser targets.

  9. Dissolution control of Mg by cellulose acetate-polyelectrolyte membranes.

    PubMed

    Yliniemi, Kirsi; Wilson, Benjamin P; Singer, Ferdinand; Höhn, Sarah; Kontturi, Eero; Virtanen, Sannakaisa

    2014-12-24

    Cellulose acetate (CA)-based membranes are used for Mg dissolution control: the permeability of the membrane is adjusted by additions of the polyelectrolyte, poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). Spin-coated films were characterized with FT-IR, and once exposed to an aqueous solution the film distends and starts acting as a membrane which controls the flow of ions and H2 gas. Electrochemical measurements (linear sweep voltammograms, open-circuit potential, and polarization) show that by altering the CA:PDMAEMA ratio the dissolution rate of Mg can be controlled. Such a control over Mg dissolution is crucial if Mg is to be considered as a viable, temporary biomedical implant material. Furthermore, the accumulation of corrosion products between the membrane and the sample diminishes the undesirable effects of high local pH and H2 formation which takes place during the corrosion process. PMID:25426707

  10. Expression of Acetate Permease-like (apl) Genes in Subsurface Communities of Geobacter Species Under Fluctuating Acetate Concentrations

    SciTech Connect

    Elifantz, H; N'Guessan, A L; Mouser, Paula; Williams, Kenneth H; Wilkins, Michael J; Risso, Carla; Holmes, Dawn; Long, Philip E; Lovley, Derek R

    2010-09-01

    The addition of acetate to uranium-contaminated aquifers in order to stimulate the growth and activity of Geobacter species that reduce uranium is a promising in situ bioremediation option. Optimizing this bioremediation strategy requires that sufficient acetate be added to promote Geobacter species growth. We hypothesized that under acetate-limiting conditions, subsurface Geobacter species would increase the expression of either putative acetate symporters genes (aplI and aplII). Acetate was added to a uranium-contaminated aquifer (Rifle, CO) in two continuous amendments separated by 5 days of groundwater flush to create changing acetate concentrations. While the expression of aplI in monitoring well D04 (high acetate) weakly correlated with the acetate concentration over time, the transcript levels for this gene were relatively constant in well D08 (low acetate). At the lowest acetate concentrations during the groundwater flush, the transcript levels of aplII were the highest. The expression of aplII decreased 2–10-fold upon acetate reintroduction. However, the overall instability of acetate concentrations throughout the experiment could not support a robust conclusion regarding the role of apl genes in response to acetate limitation under field conditions, in contrast to previous chemostat studies, suggesting that the function of a microbial community cannot be inferred based on lab experiments alone.

  11. Expression of acetate permease-like (apl) genes in subsurface communities of Geobacter species under fluctuating acetate concentrations

    SciTech Connect

    Elifantz, H.; N'Guessan, L.A.; Mouser, P.J.; Williams, K H.; Wilkins, M J.; Risso, C.; Holmes, D.E.; Long, P.E.; Lovley, D.R.

    2010-03-01

    The addition of acetate to uranium-contaminated aquifers in order to stimulate the growth and activity of Geobacter species that reduce uranium is a promising in situ bioremediation option. Optimizing this bioremediation strategy requires that sufficient acetate be added to promote Geobacter species growth. We hypothesized that under acetate-limiting conditions, subsurface Geobacter species would increase the expression of either putative acetate symporters genes (aplI and aplII). Acetate was added to a uranium-contaminated aquifer (Rifle, CO) in two continuous amendments separated by 5 days of groundwater flush to create changing acetate concentrations. While the expression of aplI in monitoring well D04 (high acetate) weakly correlated with the acetate concentration over time, the transcript levels for this gene were relatively constant in well D08 (low acetate). At the lowest acetate concentrations during the groundwater flush, the transcript levels of aplII were the highest. The expression of aplII decreased 2-10-fold upon acetate reintroduction. However, the overall instability of acetate concentrations throughout the experiment could not support a robust conclusion regarding the role of apl genes in response to acetate limitation under field conditions, in contrast to previous chemostat studies, suggesting that the function of a microbial community cannot be inferred based on lab experiments alone.

  12. ZnS/Zn(O,OH)S-based buffer layer deposition for solar cells

    DOEpatents

    Bhattacharya, Raghu N.

    2009-11-03

    The invention provides CBD ZnS/Zn(O,OH)S and spray deposited ZnS/Zn(O,OH)S buffer layers prepared from a solution of zinc salt, thiourea and ammonium hydroxide dissolved in a non-aqueous/aqueous solvent mixture or in 100% non-aqueous solvent. Non-aqueous solvents useful in the invention include methanol, isopropanol and triethyl-amine. One-step deposition procedures are described for CIS, CIGS and other solar cell devices.

  13. Using single buffers and data reorganization to implement a multi-megasample fast Fourier transform

    NASA Technical Reports Server (NTRS)

    Brown, R. D.

    1992-01-01

    Data ordering in large fast Fourier transforms (FFT's) is both conceptually and implementationally difficult. Discribed here is a method of visualizing data orderings as vectors of address bits, which enables the engineer to use more efficient data orderings and reduce double-buffer memory designs. Also detailed are the difficulties and algorithmic solutions involved in FFT lengths up to 4 megasamples (Msamples) and sample rates up to 80 MHz.

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

    PubMed

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

    2011-01-01

    Upon the addition of protons to an aqueous solution, a component of the H+ load will be bound i.e. buffered. In an aqueous solution containing a triprotic acid, H+ can be bound to three different states of the acid as well as to OH- ions that are derived from the auto-ionization of H2O. In quantifying the buffering process of a triprotic acid, one must define the partitioning of H+ among the three states of the acid and also the OH- ions in solution in order to predict the equilibrium pH value. However, previous quantitative approaches that model triprotic acid titration behaviour and used to predict the equilibrium pH rely on the mathematical convenience of electroneutrality/charge balance considerations. This fact has caused confusion in the literature, and has led to the assumption that charge balance/electroneutrality is a causal factor in modulating proton buffering (Stewart formulation). However, as we have previously shown, although charge balance can be used mathematically as a convenient tool in deriving various formulae, electroneutrality per se is not a fundamental physicochemical parameter that is mechanistically involved in the underlying buffering and proton transfer reactions. The lack of distinction between a mathematical tool, and a fundamental physicochemical parameter is in part a reason for the current debate regarding the Stewart formulation of acid-base analysis. We therefore posed the following question: Is it possible to generate an equation that defines and predicts the buffering of a triprotic acid that is based only on H+ partitioning without incorporating electroneutrality in the derivation? Towards this goal, we derived our new equation utilizing: 1) partitioning of H+ buffering; 2) conservation of mass; and 3) acid-base equilibria. In validating this model, we compared the predicted equilibrium pH with the measured pH of an aqueous solution consisting of Na2HPO4 to which HCl was added. The measured pH values were in excellent agreement with the predictions of our equation. Our results provide further important evidence that one can mathematically model the chemistry of acid-base phenomenology without relying on electroneutrality (Stewart formulation) considerations. PMID:21849064

  15. Surface Treatments of Nb by Buffered Electropolishing

    SciTech Connect

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

    2009-11-01

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

  16. Study of the Photodegradation Process of Vitamin E Acetate by Optical Absorption, Fluorescence, and Thermal Lens Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tiburcio-Moreno, J. A.; Marcelín-Jiménez, G.; Leanos-Castaneda, O. L.; Yanez-Limon, J. M.; Alvarado-Gil, J. J.

    2012-11-01

    The stability of vitamin E acetate exposed to ultraviolet (UV) light was studied using three spectroscopic methods. An ethanol solution of vitamin E acetate was treated with either UVC light (254 nm) or UVA light (366 nm) during a period of 10 min followed by a study of UV-Vis optical absorption, then by fluorescence spectroscopy excitation by UV radiation at either 290 nm or 368 nm and, finally the solution was studied by thermal lens spectroscopy. Immediately, the same solution of vitamin E acetate was subjected to the UV irradiation process until completion of six periods of irradiation and measurements. UVC light treatment induced the appearance of a broad absorption band in the range of 310 nm to 440 nm with maximum absorbance at 368 nm, which progressively grew as the time of the exposure to UVC light increases. In contrast, UVA light treatment did not affect the absorption spectra of vitamin E acetate. Fluorescence spectra of the vitamin E acetate (without UV light treatment) showed no fluorescence when excited with 368 nm while exciting with 290 nm, an intense and broad emission band (300 nm to 440 nm) with a maximum at 340 nm appeared. When vitamin E acetate was treated with UVC light, this emission band progressively decreased as the time of the UVC light irradiation grew. No signal from UV-untreated vitamin E acetate could be detected by the thermal lens method. Interestingly, as the time of the UVC light treatment increased, the thermal lens signal progressively grew. Additional experiments performed to monitor the time evolution of the process during continuous UVC treatment of the vitamin E acetate using thermal lens spectroscopy exhibited a progressive increase of the thermal lens signal reaching a plateau at about 8000 s. This study shows that the vitamin E acetate is stable when it is irradiated with UVA light, while the irradiation with UVC light induces the formation of photodegradation products. Interestingly, this photodegradation process using the study of the thermal lens effect could be followed closely even though poor absorption of the photodegraded product of the vitamin E acetate was observed at the laser wavelength used. As the thermal lens method allowed for accurate monitoring of the extent of photodegradation of the vitamin E acetate, this study opens the photodegradation process as a new application to be added to the recent applications of thermal lens spectroscopy in chemical analysis.

  17. 21 CFR 522.960b - Flumethasone acetate injection.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Flumethasone acetate injection. 522.960b Section... § 522.960b Flumethasone acetate injection. (a) Chemical name. 6-alpha,9-alpha-difluoro - 16 - alpha - methylprednisolone 21-acetate. (b) Specifications. Flumethasone injection is sterile and contains per...

  18. 21 CFR 522.960b - Flumethasone acetate injection.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Flumethasone acetate injection. 522.960b Section... § 522.960b Flumethasone acetate injection. (a) Chemical name. 6-alpha,9-alpha-difluoro - 16 - alpha - methylprednisolone 21-acetate. (b) Specifications. Flumethasone injection is sterile and contains per...

  19. 21 CFR 522.960b - Flumethasone acetate injection.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Flumethasone acetate injection. 522.960b Section... § 522.960b Flumethasone acetate injection. (a) Chemical name. 6-alpha,9-alpha-difluoro - 16 - alpha - methylprednisolone 21-acetate. (b) Specifications. Flumethasone injection is sterile and contains per...

  20. 21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the requirement of 27 CFR 21.62, being not less than 92.5 percent ethyl alcohol, each 100 gallons... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ethyl alcohol containing ethyl acetate....

  1. 21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the requirement of 27 CFR 21.62, being not less than 92.5 percent ethyl alcohol, each 100 gallons... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Ethyl alcohol containing ethyl acetate....

  2. 21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the requirement of 27 CFR 21.62, being not less than 92.5 percent ethyl alcohol, each 100 gallons... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Ethyl alcohol containing ethyl acetate....

  3. 21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the requirement of 27 CFR 21.62, being not less than 92.5 percent ethyl alcohol, each 100 gallons... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Ethyl alcohol containing ethyl acetate....

  4. 21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the requirement of 27 CFR 21.62, being not less than 92.5 percent ethyl alcohol, each 100 gallons... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ethyl alcohol containing ethyl acetate....

  5. Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins

    ERIC Educational Resources Information Center

    Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

    2011-01-01

    A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The

  6. Acetic acid vapor levels associated with facial prosthetics

    SciTech Connect

    McElroy, T.H.; Guerra, O.N.; Lee, S.A.

    1985-01-01

    The use of Silastic Medical Adhesive Type A in the fabrication of facial prostheses may cause health hazards to the patient and the operator because of acetic acid emissions. Caution must be exercised to remove acetic acid vapors from the air and unliberated acetic acid from material applied directly to the skin.

  7. 21 CFR 582.5933 - Vitamin A acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Vitamin A acetate. 582.5933 Section 582.5933 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5933 Vitamin A acetate. (a) Product. Vitamin A acetate. (b) Conditions of use....

  8. 21 CFR 582.5933 - Vitamin A acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Vitamin A acetate. 582.5933 Section 582.5933 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5933 Vitamin A acetate. (a) Product. Vitamin A acetate. (b) Conditions of use....

  9. 21 CFR 582.5933 - Vitamin A acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Vitamin A acetate. 582.5933 Section 582.5933 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5933 Vitamin A acetate. (a) Product. Vitamin A acetate. (b) Conditions of use....

  10. 21 CFR 582.5933 - Vitamin A acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Vitamin A acetate. 582.5933 Section 582.5933 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5933 Vitamin A acetate. (a) Product. Vitamin A acetate. (b) Conditions of use....

  11. 21 CFR 582.5933 - Vitamin A acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Vitamin A acetate. 582.5933 Section 582.5933 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5933 Vitamin A acetate. (a) Product. Vitamin A acetate. (b) Conditions of use....

  12. Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins

    ERIC Educational Resources Information Center

    Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

    2011-01-01

    A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

  13. Acetate concentrations and oxidation in salt marsh sediments

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Acetate concentrations and rates of acetate oxidation and sulfate reduction were measured in S. alterniflora sediments in New Hampshire and Massachusetts. Pore water extracted from cores by squeezing or centrifugation contained in greater than 0.1 mM acetate and, in some instances, greater than 1.0 mM. Pore water sampled nondestructively contained much less acetate, often less than 0.01 mM. Acetate was associated with roots, and concentrations varied with changes in plant physiology. Acetate turnover was very low whether whole core or slurry incubations were used. Radiotracers injected directly into soils yielded rates of sulfate reduction and acetate oxidation not significantly different from core incubation techniques. Regardless of incubation method, acetate oxidation did not account for a substantial percentage of sulfate reduction. These results differ markedly from data for unvegetated coastal sediments where acetate levels are low, oxidation rate constants are high, and acetate oxication rates greatly exceed rates of sulfate reduction. The discrepancy between rates of acetate oxidation and sulfate reduction in these marsh soils may be due either to the utilization of substrates other than acetate by sulfate reducers or artifacts associated with measurements of organic utilization by rhizosphere bacteria. Care must be taken when interpreting data from salt marsh sediments since the release of material from roots during coring may affect the concentrations of certain compounds as well as influencing results obtained when sediment incubations are employed.

  14. Lymph node revealing solution: a rapid method for the fixation of cystectomy specimens.

    PubMed

    Koren, R; Paz, A; Konichezsky, M; Sadikov, E; Klein, B; Livne, P; Gal, R

    1999-01-01

    The objective of this study was to describe the use of the lymph node revealing solution (LNRS) for rapid fixation of total cystectomy specimens, and to compare it with formalin fixation. LNRS is a mixture of 95% ethanol, diethyl ether, glacial acetic acid and buffered formalin (65:20:5:10 v/v) prepared under a fume-hood. Sixteen consecutive cystectomy specimens were fixed for two hours either in LNRS or in buffered formalin. Representative sections were embedded in paraffin, sectioned and stained with H&E, periodic acid Schiff, alcian-blue, and immunostained for cytokeratins 20, high and low molecular weight cytokeratins, prostatic specific antigen, Factor VIII related antigen, s-100 protein, and protein kinase C isoenzymes. Results showed that the tissues were well fixed after 2 hours in LNRS, and were not fixed after 2 hours in formalin. Processing and sectioning of the paraffin blocks of the LNRS fixed tissue was excellent; it was impossible in the sections fixed for 2 hours in formalin. All the stains were excellent after LNRS fixation. We conclude that fixation of cystectomy specimens in LNRS requires only two hours and results in excellent stained slides. It is therefore recommended for cystectomy specimens. PMID:10093825

  15. Aerosol buffering of marine boundary layer cloudiness

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  16. 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... § 170.3(n)(10) of this chapter; 0.5 percent for chewing gum as defined in § 170.3(n)(6) of this...

  17. Calcium magnesium acetate production and cost reduction

    SciTech Connect

    Leuschner, A.P.

    1988-02-01

    The New York State Energy Research and Development Authority (Energy Authority), Consolidated Edison Company of New York, Inc. (ConEd), the New York State Department of Transportation (NYSDOT), the New York State Thruway Authority (NYSTA), Chevron Chemical Company, the National Corn Growers Association (NCGA), and the Massachusetts Department of Public Works (MDPW) sponsored a research program to develop technology capable of producing Calcium Magnesium Acetate (CMA), an alternative road deicer, at a quality and cost which will allow its increased use. The objectives of this program were to determine the feasibility of: (1) producing CMA from regionally available waste and low grade organic feedstocks via biochemical engineering technologies; (2) operating the fermentation at concentrated product levels to reduce energy requirements and minimize drying process costs; (3) using this production approach to produce an environmentally acceptable CMA product; and (4) using and adapting an existing facility for a CMA commercial demonstration plant. The experimental program included:(1) selection of microorganisms for their ability to grow in the absence of sodium chloride and to tolerate high concentrations of calcium, magnesium, and acetate ions; (2) analysis of waste feedstocks for their potential conversion to acetate; (3) analysis of waste organic material for impurities in CMA that could carry over into the environment; (4) batch experiments to determine pH tolerance, growth in the absence of sodium chloride (NaCl), tolerance to magnesium, calcium and acetate ions, effect of substrate concentration, acid distribution, and acid production; and (5) semi-continuous laboratory scale anaerobic digestion experiments to determine loading rates, conversion efficiencies, and other design data. 67 refs., 33 figs., 66 tabs.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Technical Reports Server (NTRS)

    Wolfe, T.

    1984-01-01

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

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

    SciTech Connect

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

    1994-04-01

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

  1. Photonic integrated circuit optical buffer for packet-switched networks.

    PubMed

    Burmeister, Emily F; Mack, John P; Poulsen, Henrik N; Masanović, Milan L; Stamenić, Biljana; Blumenthal, Daniel J; Bowers, John E

    2009-04-13

    A chip-scale optical buffer performs autonomous contention resolution for 40-byte packets with 99% packet recovery. The buffer consists of a fast, InP-based 2 x 2 optical switch and a silica-on-silicon low loss delay loop. The buffer is demonstrated in recirculating operation, but may be reconfigured in feed-forward operation for longer packet lengths. The recirculating buffer provides packet storage in integer multiples of the delay length of 12.86 ns up to 64.3 ns with 98% packet recovery. The buffer is used to resolve contention between two 40 Gb/s packet streams using multiple photonic chip optical buffers. PMID:19365489

  2. Access to aldehydo acetals of sugars via palladium-catalyzed oxidation of alpha,beta-unsaturated cyclic acetals.

    PubMed

    Fayet, Catherine; Gelas, Jacques; Danková, Katerina; Yokaris, Alexandre

    2002-11-19

    The palladium(II)-catalyzed oxidation of alpha,beta-unsaturated cyclic acetals derived from mono- and disaccharides leads in appreciable yields to new aldehydo acetals which, overall, results in an anti-Markovnikov addition. PMID:12433496

  3. Co-fermentation of acetate and sugars facilitating microbial lipid production on acetate-rich biomass hydrolysates.

    PubMed

    Gong, Zhiwei; Zhou, Wenting; Shen, Hongwei; Yang, Zhonghua; Wang, Guanghui; Zuo, Zhenyu; Hou, Yali; Zhao, Zongbao K

    2016-05-01

    The process of lignocellulosic biomass routinely produces a stream that contains sugars plus various amounts of acetic acid. As acetate is known to inhibit the culture of microorganisms including oleaginous yeasts, little attention has been paid to explore lipid production on mixtures of acetate and sugars. Here we demonstrated that the yeast Cryptococcus curvatus can effectively co-ferment acetate and sugars for lipid production. When mixtures of acetate and glucose were applied, C. curvatus consumed both substrates simultaneously. Similar phenomena were also observed for acetate and xylose mixtures, as well as acetate-rich corn stover hydrolysates. More interestingly, the replacement of sugar with equal amount of acetate as carbon source afforded higher lipid titre and lipid content. The lipid products had fatty acid compositional profiles similar to those of cocoa butter, suggesting their potential for high value-added fats and biodiesel production. This co-fermentation strategy should facilitate lipid production technology from lignocelluloses. PMID:26874438

  4. Inhibition of enamel demineralization by buffering effect of S-PRG filler-containing dental sealant.

    PubMed

    Kaga, Masayuki; Kakuda, Shinichi; Ida, Yusuke; Toshima, Hirokazu; Hashimoto, Masanori; Endo, Kazuhiko; Sano, Hidehiko

    2014-02-01

    The buffering capacity and inhibitory effects on enamel demineralization of two commercially available dental sealants were evaluated in this study. The effects of filler particles were also examined. Disks of enamel and cured sealant materials of BeautiSealant (silica or S-PRG filler) or Teethmate F-1 were incubated in lactic acid solutions (pH 4.0) for 1-6d. The pH changes and amounts of ions released in the solutions were assessed, and enamel surfaces were observed using a scanning electron microscope. The pH of the solution with BeautiSealant (S-PRG filler) was neutralized from pH 4.0 to pH 6.1 (after incubation for 1d) and from pH 4.0 to pH 6.7 (after incubation for 6d). In addition, no release of calcium ions was detected and the enamel surface was morphologically intact in scanning electron microscopy images. However, the pH of the solution with Teethmate F-1 remained below pH 4.0 during incubation from days 1 to 6. Calcium release was increased in solutions up to and after 6d of incubation. Scanning electron microscopy images showed that the structures of hydroxyapatite rods were exposed at the specimen surfaces as a result of demineralization. Ions released from S-PRG filler-containing dental sealant rapidly buffered the lactic acid solution and inhibited enamel demineralization. PMID:24372898

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

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

    USGS Publications Warehouse

    Melcher, Cynthia P.; Skagen, Susan K.

    2005-01-01

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

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

    DOEpatents

    Compaan, Alvin D.; Plotnikov, Victor V.

    2014-09-09

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

  8. An assessment of buffer strips for improving damage tolerance

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

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

  10. Solubilization of proteins: the importance of lysis buffer choice.

    PubMed

    Peach, Mandy; Marsh, Noelle; Miskiewicz, Ewa I; MacPhee, Daniel J

    2015-01-01

    The efficient extraction of proteins of interest from cells and tissues is not always straightforward. Here we demonstrate the differences in extraction of the focal adhesion protein Kindlin-2 from choriocarcinoma cells using NP-40 and RIPA lysis buffer. Furthermore, we demonstrate the use of a more denaturing urea/thiourea lysis buffer for solubilization, by comparing its effectiveness for solubilization of small heat-shock proteins from smooth muscle with the often utilized RIPA lysis buffer. Overall, the results demonstrate the importance of establishing the optimal lysis buffer for specific protein solubilization within the experimental workflow. PMID:26043989

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

    PubMed

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

    2014-08-19

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

  12. Novel biocompatible and self-buffering ionic liquids for biopharmaceutical applications.

    PubMed

    Taha, Mohamed; Almeida, Mafalda R; Silva, Francisca A E; Domingues, Pedro; Ventura, Sónia P M; Coutinho, João A P; Freire, Mara G

    2015-03-16

    Antibodies obtained from egg yolk of immunized hens, immunoglobulin Y (IgY), are an alternative to the most focused mammal antibodies, because they can be obtained in higher titers by less invasive approaches. However, the production cost of high-quality IgY for large-scale applications remains higher than that of other drug therapies due to the lack of efficient purification methods. The search for new purification platforms is thus vital. The solution could be liquid-liquid extraction by using aqueous biphasic systems (ABS). Herein, we report the extraction and attempted purification of IgY from chicken egg yolk by using a new ABS composed of polymers and Good's buffer ionic liquids (GB-ILs). New self-buffering and biocompatible ILs based on the cholinium cation and anions derived from Good's buffers were synthesized and the self-buffering characteristics and toxicity were characterized. Moreover, when these GB-ILs are combined with PPG 400 (poly(propylene) glycol with a molecular weight of 400 g mol(-1)) to form ABS, extraction efficiencies, of the water-soluble fraction of proteins, ranging between 79 and 94% were achieved in a single step. Based on computational investigations, we also demonstrate that the preferential partitioning of IgY for the GB-IL-rich phase is dominated by hydrogen-bonding and van der Waals interactions. PMID:25652351

  13. Transport through a Heterogeneous Alluvial Aquifer beneath an Agricultural Riparian Buffer

    NASA Astrophysics Data System (ADS)

    Johnson, R.; Mather, A. L.; Smith, E. A.; Green, C. T.

    2012-12-01

    Riparian buffer zones between agricultural fields and streams are intended to attenuate the groundwater transport of non-point-source pollutants. However, if the spatial variability in the alluvial aquifer structure provides pathways for rapid transit across the buffer, the effectiveness for mitigating transport of pollutants to the stream may be limited. The main objective of this work was to examine the effects of alluvial aquifer heterogeneity on groundwater transport beneath an agricultural riparian buffer. This was assessed first by performing a natural-gradient tracer experiment and characterizing the site heterogeneity through hydraulic conductivity profiling. Second, the field hydraulic conductivity data were used with a meandering geostatistical model to represent aquifer heterogeneity and a numerical groundwater model was constructed to simulate the tracer experiment. The tracer experiment showed that a portion of the injected plume (~10% of the total mass) moved at high velocity, while a significant fraction of the mass moved slowly and remained near the injection location. Both the tracer test and the numerical modeling indicate that transport velocities of a meter per day are likely to be present in localized regions throughout the riparian buffer. This highlights the dependence of solute residence time in the riparian zone, and therefore the concentrations arriving in rivers, on the local geological structure.

  14. Experimental evidence of an acetate transporter protein and characterization of acetate activation in aceticlastic methanogenesis of Methanosarcina mazei.

    PubMed

    Welte, Cornelia; Kröninger, Lena; Deppenmeier, Uwe

    2014-10-01

    Aceticlastic methanogens metabolize acetate to methane and carbon dioxide. The central metabolism and the electron transport chains of these organisms have already been investigated. However, no particular attention has been paid to the mechanism by which acetate enters the archaeal cell. In our study we investigated Methanosarcina mazei acetate kinase (Ack) and the acetate uptake reaction. At a concentration of 2 mM acetate, the Ack activity in cell extract of M. mazei was not limiting for the methane formation rate. Instead, the methanogenesis rate was controlled by the substrate concentration and increased 10-fold at 10 mM acetate. Subsequently, we analyzed the involvement of the putative acetate permease MM_0903 using a corresponding deletion mutant. At 2 mM acetate, only 25% of the wild-type methane formation rate was measured in the mutant. This indicated that the supply of acetate to Ack was limiting the rate of methane formation. Moreover, the mutant revealed an increased acetate kinase activity compared with the wild type. These results show for the first time that an acetate transporter is involved in aceticlastic methanogenesis and may be an important factor in the acetate threshold concentration for methanogenesis of Methanosarcina spp. PMID:25088360

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

    PubMed Central

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

    2013-01-01

    Ca2+ signaling regulates cell function. This is subject to modulation by H+ ions that are universal end-products of metabolism. Due to slow diffusion and common buffers, changes in cytoplasmic [Ca2+] ([Ca2+]i) or [H+] ([H+]i) can become compartmentalized, leading potentially to complex spatial Ca2+/H+ coupling. This was studied by fluorescence imaging of cardiac myocytes. An increase in [H+]i, produced by superfusion of acetate (salt of membrane-permeant weak acid), evoked a [Ca2+]i rise, independent of sarcolemmal Ca2+ influx or release from mitochondria, sarcoplasmic reticulum, or acidic stores. Photolytic H+ uncaging from 2-nitrobenzaldehyde also raised [Ca2+]i, and the yield was reduced following inhibition of glycolysis or mitochondrial respiration. H+ uncaging into buffer mixtures in vitro demonstrated that Ca2+ unloading from proteins, histidyl dipeptides (HDPs; e.g., carnosine), and ATP can underlie the H+-evoked [Ca2+]i rise. Raising [H+]i tonically at one end of a myocyte evoked a local [Ca2+]i rise in the acidic microdomain, which did not dissipate. The result is consistent with uphill Ca2+ transport into the acidic zone via Ca2+/H+ exchange on diffusible HDPs and ATP molecules, energized by the [H+]i gradient. Ca2+ recruitment to a localized acid microdomain was greatly reduced during intracellular Mg2+ overload or by ATP depletion, maneuvers that reduce the Ca2+-carrying capacity of HDPs. Cytoplasmic HDPs and ATP underlie spatial Ca2+/H+ coupling in the cardiac myocyte by providing ion exchange and transport on common buffer sites. Given the abundance of cellular HDPs and ATP, spatial Ca2+/H+ coupling is likely to be of general importance in cell signaling. PMID:23676270

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

    NASA Astrophysics Data System (ADS)

    Liew, Soung C.

    1994-02-01

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

  17. Overview on mechanisms of acetic acid resistance in acetic acid bacteria.

    PubMed

    Wang, Bin; Shao, Yanchun; Chen, Fusheng

    2015-02-01

    Acetic acid bacteria (AAB) are a group of gram-negative or gram-variable bacteria which possess an obligate aerobic property with oxygen as the terminal electron acceptor, meanwhile transform ethanol and sugar to corresponding aldehydes, ketones and organic acids. Since the first genus Acetobacter of AAB was established in 1898, 16 AAB genera have been recorded so far. As the main producer of a world-wide condiment, vinegar, AAB have evolved an elegant adaptive system that enables them to survive and produce a high concentration of acetic acid. Some researches and reviews focused on mechanisms of acid resistance in enteric bacteria and made the mechanisms thoroughly understood, while a few investigations did in AAB. As the related technologies with proteome, transcriptome and genome were rapidly developed and applied to AAB research, some plausible mechanisms conferring acetic acid resistance in some AAB strains have been published. In this review, the related mechanisms of AAB against acetic acid with acetic acid assimilation, transportation systems, cell morphology and membrane compositions, adaptation response, and fermentation conditions will be described. Finally, a framework for future research for anti-acid AAB will be provided. PMID:25575804

  18. Numerical modeling of field scale application of ground silicate minerals for groundwater pH buffering

    NASA Astrophysics Data System (ADS)

    Brovelli, A.; Barry, D. A.; Lacroix, E. M.; Holliger, C.

    2012-12-01

    Recently, it was shown that ground silicate minerals are a potentially suitable pH buffering material for contaminated soils undergoing acidification, for example due to acid mine leachate and coal pile runoff infiltration, as well as during the degradation of chlorinated ethenes (Lacroix et al., 2012, Doi: 10.1007/s11270-011-1058-4). Compared to traditional buffering methods, such as the circulation of an alkaline solution, silicate minerals are appealing because they are long-term sources of buffering capacity. In this work, the applicability of ground silicate minerals to a realistic field scale scenario was examined, and possible solutions to deliver the silicates in the contaminated area were explored. To this end, a reactive transport model was developed using PHAST to study particle filtration and dissolution, pH evolution and the effect of soil and groundwater geochemistry. The model accounts for particle advection and dispersion, deep-bed filtration, porosity and hydraulic conductivity changes associated with deposition and mobilization. The deep-bed filtration coefficients vary with the flow rate and the composition of the pore-solution, ionic strength and, in particular, pH. Experimental data taken from the literature were used to calibrate and validate the deep-bed filtration model and the relationships that describe porosity and hydraulic conductivity variations. A satisfactory comparison was found in most situations. A two-dimensional model was setup to study the delivery and spreading of silicate minerals in a hypothetical contaminated site. Different injection scenarios were tested. It was found that the injection flow rate and well configuration strongly affect the distribution of silicates and therefore the buffering efficiency. In general, it was observed that the distance between two injection wells should not exceed 25 m to ensure a sufficiently homogeneous distribution of the substrate. It was further observed that the optimal size of the injected particles is around 5 μm. Since ground minerals have a rather large reactive surface area, relatively small amounts of silicate minerals are needed to guarantee sufficient buffering in most situations. For example, to degrade 40 mM of TCE to ethene in 100 d, 10 g (kg soil)-1 of silicates are sufficient. With this amount, the variation of the soil porosity is less than 2%, and the associated hydraulic conductivity change predicted is also small. In summary, the numerical experiments performed confirmed that the injection of silicate minerals can be a viable strategy to provide pH buffering capacity to soils.

  19. Developing Suitable Buffers to Capture Transport Cycling Behavior

    PubMed Central

    Madsen, Thomas; Schipperijn, Jasper; Christiansen, Lars Breum; Nielsen, Thomas Sick; Troelsen, Jens

    2014-01-01

    The association between neighborhood built environment and cycling has received considerable attention in health literature over the last two decades, but different neighborhood definitions have been used and it is unclear which one is most appropriate. Administrative or fixed residential spatial units (e.g., home-buffer-based neighborhoods) are not necessarily representative for environmental exposure. An increased understanding of appropriate neighborhoods is needed. GPS cycling tracks from 78 participants for 7 days form the basis for the development and testing of different neighborhood buffers for transport cycling. The percentage of GPS points per square meter was used as indicator of the effectiveness of a series of different buffer types, including home-based network buffers, shortest route to city center buffers, and city center-directed ellipse-shaped buffers. The results show that GPS tracks can help us understand where people go and stay during the day, which can help us link built environment with cycling. Analysis showed that the further people live from the city center, the more elongated are their GPS tracks, and the better an ellipse-shaped directional buffer captured transport cycling behavior. In conclusion, we argue that in order to be able to link built environment factors with different forms of physical activity, we must study the most likely area people use. In this particular study, to capture transport cycling, with its relatively large radius of action, city center-directed ellipse-shaped buffers yielded better results than traditional home-based network buffer types. The ellipse-shaped buffer types could therefore be considered an alternative to more traditional buffers or administrative units in future studies of transport cycling behavior. PMID:24926478

  20. Adaptation and tolerance of bacteria against acetic acid.

    PubMed

    Trček, Janja; Mira, Nuno Pereira; Jarboe, Laura R

    2015-08-01

    Acetic acid is a weak organic acid exerting a toxic effect to most microorganisms at concentrations as low as 0.5 wt%. This toxic effect results mostly from acetic acid dissociation inside microbial cells, causing a decrease of intracellular pH and metabolic disturbance by the anion, among other deleterious effects. These microbial inhibition mechanisms enable acetic acid to be used as a preservative, although its usefulness is limited by the emergence of highly tolerant spoilage strains. Several biotechnological processes are also inhibited by the accumulation of acetic acid in the growth medium including production of bioethanol from lignocellulosics, wine making, and microbe-based production of acetic acid itself. To design better preservation strategies based on acetic acid and to improve the robustness of industrial biotechnological processes limited by this acid's toxicity, it is essential to deepen the understanding of the underlying toxicity mechanisms. In this sense, adaptive responses that improve tolerance to acetic acid have been well studied in Escherichia coli and Saccharomyces cerevisiae. Strains highly tolerant to acetic acid, either isolated from natural environments or specifically engineered for this effect, represent a unique reservoir of information that could increase our understanding of acetic acid tolerance and contribute to the design of additional tolerance mechanisms. In this article, the mechanisms underlying the acetic acid tolerance exhibited by several bacterial strains are reviewed, with emphasis on the knowledge gathered in acetic acid bacteria and E. coli. A comparison of how these bacterial adaptive responses to acetic acid stress fit to those described in the yeast Saccharomyces cerevisiae is also performed. A systematic comparison of the similarities and dissimilarities of the ways by which different microbial systems surpass the deleterious effects of acetic acid toxicity has not been performed so far, although such exchange of knowledge can open the door to the design of novel approaches aiming the development of acetic acid-tolerant strains with increased industrial robustness in a synthetic biology perspective. PMID:26142387