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1

ESTIMATION OF PHOSPHATE ESTER HYDROLYSIS RATE CONSTANTS - ALKALINE HYDROLYSIS  

EPA Science Inventory

SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to allow the calculation of alkaline hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition state...

2

ESTIMATION OF PHOSPHATE ESTER HYDROLYSIS RATE CONSTANTS. I. ALKALINE HYDROLYSIS  

EPA Science Inventory

SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to allow the calculation of alkaline hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition state...

3

Efficiency of alkaline hydrolysis method in environment protection.  

PubMed

Development of new technologies for the efficient use of proteins of animal origin, apart from heat treatment in rendering facilities that was used to date, has become the primary goal of the integral waste management system. The emergence of bovine spongiform encephalopathy in Europe and in the World in the 1990s opened up new questions regarding medical safety and use of meat bone meal in the animal feed, which is produced by processing animal waste. Animal waste is divided into three categories, out of which the first category is high-risk waste. Alkaline hydrolysis is alternative method for management of animal by-products not intended for human diet and imposes itself as one of the solutions for disposal of high-risk proteins. The paper will present the analyses of animal by-products not intended for human diet treated in laboratory reactor for alkaline hydrolysis, as one of the two recognized methods in EU for the disposal of this type of material and use in fertilization. PMID:25144977

Kricka, Tajana; Toth, Ivan; Kalambura, Sanja; Jovici?, Nives

2014-06-01

4

DOI: 10.1002/cphc.201402016 Phosphate Monoester Hydrolysis by Trinuclear Alkaline  

E-print Network

DOI: 10.1002/cphc.201402016 Phosphate Monoester Hydrolysis by Trinuclear Alkaline Phosphatase; DFT magnesium and two zinc atoms) that cat- alyzes the hydrolysis of a broad range of phosphate monoest- ers in enzymatic hydrolysis of phos- phate esters, for the investigation of catalytic properties of bi- nuclear

Liao, Rongzhen

5

Spectrophotometric determination of paracetamol with microwave assisted alkaline hydrolysis  

NASA Astrophysics Data System (ADS)

A novel and rapid spectrophotometric method for the determination of paracetamol is proposed in this paper. The proposed method is based on the microwave assisted alkaline hydrolysis of paracetamol to p-aminophenol that reacts with S 2- in the presence of Fe 3+ as oxidant to produce a methylene blue-like dye having an absorptivity maximum at 540 nm. The experiment showed that paracetamol could be hydrolysed quantitatively to p-aminophenol in only 1.5 min under radiation power 640 W using a microwave in NaOH medium. The system obeys Beer's law in the range of 0-3.0×10 -4 mol l -1 paracetamol. The molar absorptivity and Sandell's sensitivity were found to be 3.2×10 3 l mol -1 cm -1 and 0.047 ?g cm -2, respectively. The relative standard deviation ( n=11) was 1.7% for 8.0×10 -5 mol l -1 paracetamol. The method has been applied successfully to analysis of paracetamol in pharmaceutical preparation.

Xu, Chunli; Li, Baoxin

2004-07-01

6

Survival of prokaryotes in a polluted waste dump during remediation by alkaline hydrolysis.  

PubMed

A combination of culture-dependent and culture-independent techniques was used to characterize bacterial and archaeal communities in a highly polluted waste dump and to assess the effect of remediation by alkaline hydrolysis on these communities. This waste dump (Breakwater 42), located in Denmark, contains approximately 100 different toxic compounds including large amounts of organophosphorous pesticides such as parathions. The alkaline hydrolysis (12 months at pH >12) decimated bacterial and archaeal abundances, as estimated by 16S rRNA gene-based qPCR, from 2.1 × 10(4) and 2.9 × 10(3) gene copies per gram wet soil respectively to below the detection limit of the qPCR assay. Clone libraries constructed from PCR-amplified 16S rRNA gene fragments showed a significant reduction in bacterial diversity as a result of the alkaline hydrolysis, with preferential survival of Betaproteobacteria, which increased in relative abundance from 0 to 48 %. Many of the bacterial clone sequences and the 27 isolates were related to known xenobiotic degraders. An archaeal clone library from a non-hydrolyzed sample showed the presence of three main clusters, two representing methanogens and one representing marine aerobic ammonia oxidizers. Isolation of alkalitolerant bacterial pure cultures from the hydrolyzed soil confirmed that although alkaline hydrolysis severely reduces microbial community diversity and size certain bacteria survive a prolonged alkaline hydrolysis process. Some of the isolates from the hydrolyzed soil were capable of growing at high pH (pH 10.0) in synthetic media indicating that they could become active in in situ biodegradation upon hydrolysis. PMID:24532314

Nielsen, Marie Bank; Kjeldsen, Kasper Urup; Lever, Mark Alexander; Ingvorsen, Kjeld

2014-04-01

7

Detection of bound phenolic acids: prevention by ascorbic acid and ethylenediaminetetraacetic acid of degradation of phenolic acids during alkaline hydrolysis  

Microsoft Academic Search

The experimental conditions commonly used to detect bound phenolic acids by alkaline hydrolysis result in loss of several phenolic acids, particularly dihydroxy-derivatives (caffeic acid, dihydrocaffeic acid, homogentisic acid). In this study we show that the addition of ascorbic acid, a strong antioxidant, and ethylenediaminetetraacetic acid, a metal chelator, totally prevent the loss of phenolic acids during alkaline hydrolysis. In these

M Nardini; E Cirillo; F Natella; D Mencarelli; A Comisso; C Scaccini

2002-01-01

8

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

PubMed

Magnesium ammonium phosphate (MAP) method was used to recover orthophosphate (PO?(3-)-P) and ammonium nitrogen (NH4(+)-N) from the alkaline hydrolysis supernatant of excess sludge. To reduce alkali consumption and decrease the pH of the supernatant, two-stage alkaline hydrolysis process (TSAHP) was designed. The results showed that the release efficiencies of PO?(3-)-P and NH?(+)-N were 41.96% and 7.78%, respectively, and the pH of the supernatant was below 10.5 under the running conditions with initial pH of 13, volume ratio (sludge dosage/water dosage) of 1.75 in second-stage alkaline hydrolysis reactor, 20 g/L of sludge concentration in first-stage alkaline hydrolysis reactor. The order of parameters influencing MAP reaction was analyzed and the optimized conditions of MAP reaction were predicted through the response surface methodology. The recovery rates of PO?(3-)-P and NH?(+)-N were 46.88% and 16.54%, respectively under the optimized conditions of Mg/P of 1.8, pH 9.7 and reaction time of 15 min. PMID:24880806

Bi, Wei; Li, Yiyong; Hu, Yongyou

2014-08-01

9

Total fractionation of green tea residue by microwave-assisted alkaline pretreatment and enzymatic hydrolysis.  

PubMed

Total refinery of constituents of green tea residue was achieved by combination of microwave-assisted alkaline pretreatment and enzymatic hydrolysis. Alkaline pretreatment was effective at separating pectic polysaccharides, protein, phenolic compounds and aliphatic compounds (probably originating from cuticular components), and the solubilization rate was attained 64–74% by heating at 120–200 °C. The higher heating value (HHV) of alkali-soluble fraction attained 20.1 MJ/kg, indicating its usability as black-liquor-like biofuel. Successive cellulolytic enzymatic hydrolysis mainly converted cellulose into glucose and attained the maximum solubilization rate of 89%. Final residue was predominantly composed of aliphatic cuticular components with high proportion in 9,10,18-trihydroxyoctadecanoic acid (30.1–48.6%). These cuticular components are potential alternative feedstock for aliphatic compounds commonly found in oil plants. PMID:23384782

Tsubaki, Shuntaro; Azuma, Jun-ichi

2013-03-01

10

Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii  

NASA Astrophysics Data System (ADS)

A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity, even at low temperature, but the characteristics of the hydrolysis with this enzyme are still unclear. The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties of protease 894. After investigating the intrinsic relationship between the degree of hydrolysis and several factors, including initial reaction pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time, the kinetics model was established. This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0, temperature of 30°C, substrate concentration of 10% (w/v), enzyme concentration of 2 500 U/g, and hydrolysis time of 160 min. The kinetic characteristics of the protease for the hydrolysis of P. martensii were obtained. The inactivation constant was found to be 15.16/min, and the average relative error between the derived kinetics model and the actual measurement was only 3.04%, which indicated a high degree of fitness. Therefore, this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease, which has potential applications in the food industry.

Chen, Xin; Chen, Hua; Cai, Bingna; Liu, Qingqin; Sun, Huili

2013-05-01

11

Phosphate monoester hydrolysis by trinuclear alkaline phosphatase; DFT study of transition States and reaction mechanism.  

PubMed

Alkaline phosphatase (AP) is a trinuclear metalloenzyme that catalyzes the hydrolysis of a broad range of phosphate monoesters to form inorganic phosphate and alcohol (or phenol). In this paper, by using density functional theory with a model based on a crystal structure, the AP-catalyzed hydrolysis of phosphate monoesters is investigated by calculating two substrates, that is, methyl and p-nitrophenyl phosphates, which represent alkyl and aryl phosphates, respectively. The calculations confirm that the AP reaction employs a "ping-pong" mechanism involving two chemical displacement steps, that is, the displacement of the substrate leaving group by a Ser102 alkoxide and the hydrolysis of the phosphoseryl intermediate by a Zn2-bound hydroxide. Both displacement steps proceed via a concerted associative pathway no matter which substrate is used. Other mechanistic aspects are also studied. Comparison of our calculations with linear free energy relationships experiments shows good agreement. PMID:24683174

Chen, Shi-Lu; Liao, Rong-Zhen

2014-08-01

12

Ab initio study of the alkaline hydrolysis of a thio-?-lactam structure  

NASA Astrophysics Data System (ADS)

The alkaline hydrolysis of a thio-?-lactam in the gas phase was examined in the light of RHF and DFT ab initio calculations. The solvent effect was considered via IPCM computations. The tetrahedral intermediate for the thio-?-lactam studied is unstable, so the compound evolves directly to the corresponding thio-azethidin-2-one open ring with cleavage of the C-S bond. The end-products obtained bear a carbamate group, which suggests that the thio-?-lactam might be an effective inhibitor for ?-lactamases.

Coll, Miguel; Frau, Juan; Vilanova, Bartolomé; Donoso, Josefa; Muñoz, Francisco

2000-08-01

13

Theoretical study of the alkaline hydrolysis of an aza-?-lactam derivative of clavulanic acid  

NASA Astrophysics Data System (ADS)

DFT calculations based on the hybrid functional B3LYP/6-31+G * were used to study the alkaline hydrolysis of an aza-clavulanic acid, which results from the substitution of the carbon atom at position 6 in clavulanic acid by a nitrogen atom. The presence of the nitrogen atom endows the compound with special properties; in fact, once formed, the tetrahedral intermediate can evolve with cleavage of the N 4-C 7 or N 6-C 7 bond, which obviously leads to different reaction products. These differential bond cleavages may play a central role in the inactivation of ?-lactamases, so the compound may be a powerful inactivator of these enzymes.

Garcías, Rafael C.; Coll, Miguel; Donoso, Josefa; Muñoz, Francisco

2003-04-01

14

Lignin recovery from alkaline hydrolysis and glycerolysis of oil palm fiber  

NASA Astrophysics Data System (ADS)

In the present work, two types of treatment namely alkaline hydrolysis and glycerolysis have been conducted for lignin extraction from oil palm empty fruit bunch (EFB) fiber. Lignin has been retrieved from two sequential methods, which was the klason lignin from residue and lignin from precipitation of the filtrate. Alkaline hydrolysis was performed using 10% NaOH solution at room condition. This has extracted 13.0 % lignin. On the other hand, glycerolysis was carried out using 70% glycerol catalyzed with 5% of 1 M NaOH at 60-70 °C. This has successfully extracted 16.0% lignin. The SEM micrographs exhibited some physical changes on the surface where the impurities and waxes have been removed, exposing the, lumen. Besides that, FTIR analysis was conducted on untreated EFB, treated EFB and extracted lignin. Delignification of EFB fiber was confirmed based on the intensity reduction at 1245 cm-1 that showed lignin was removed from the fiber. The presence of CO, CC and CC aromatic peaks in the FTIR spectra of the dried filtrate gave an evidence on the presence of lignin.

Hassan, Nur Syakilla; Badri, Khairiah Haji

2014-09-01

15

Enhanced enzymatic hydrolysis and ethanol production from cashew apple bagasse pretreated with alkaline hydrogen peroxide.  

PubMed

The effect of combinations and ratios between different enzymes has been investigated in order to assess the optimal conditions for hydrolysis of cashew apple bagasse pretreated with alkaline hydrogen peroxide (the solids named CAB-AHP). The separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes were evaluated in the ethanol production. The enzymatic hydrolysis conducted with cellulase complex and ?-glucosidase in a ratio of 0.61:0.39, enzyme loading of 30FPU/gCAB-AHP and 66CBU/gCAB-AHP, respectively, using 4% cellulose from CAB-AHP, turned out to be the most effective conditions, with glucose and xylose yields of 511.68mg/gCAB-AHP and 237.8mg/gCAB-AHP, respectively. Fermentation of the pure hydrolysate by Kluyveromyces marxianus ATCC 36907 led to an ethanol yield of 61.8kg/tonCAB, corresponding to 15g/L ethanol and productivity of 3.75g/(Lh). The ethanol production obtained for SSF process using K. marxianus ATCC 36907 was 18g/L corresponding to 80% yield and 74.2kg/tonCAB. PMID:25545094

da Costa, Jessyca Aline; Marques, José Edvan; Gonçalves, Luciana Rocha Barros; Rocha, Maria Valderez Ponte

2015-03-01

16

The Alkaline Hydrolysis of Sulfonate Esters: Challenges in Interpreting Experimental and Theoretical Data  

PubMed Central

Sulfonate ester hydrolysis has been the subject of recent debate, with experimental evidence interpreted in terms of both stepwise and concerted mechanisms. In particular, a recent study of the alkaline hydrolysis of a series of benzene arylsulfonates (Babtie et al., Org. Biomol. Chem.10, 2012, 8095) presented a nonlinear Brønsted plot, which was explained in terms of a change from a stepwise mechanism involving a pentavalent intermediate for poorer leaving groups to a fully concerted mechanism for good leaving groups and supported by a theoretical study. In the present work, we have performed a detailed computational study of the hydrolysis of these compounds and find no computational evidence for a thermodynamically stable intermediate for any of these compounds. Additionally, we have extended the experimental data to include pyridine-3-yl benzene sulfonate and its N-oxide and N-methylpyridinium derivatives. Inclusion of these compounds converts the Brønsted plot to a moderately scattered but linear correlation and gives a very good Hammett correlation. These data suggest a concerted pathway for this reaction that proceeds via an early transition state with little bond cleavage to the leaving group, highlighting the care that needs to be taken with the interpretation of experimental and especially theoretical data. PMID:24279349

2013-01-01

17

Scale-up and integration of alkaline hydrogen peroxide pretreatment, enzymatic hydrolysis, and ethanolic fermentation.  

PubMed

Alkaline hydrogen peroxide (AHP) has several attractive features as a pretreatment in the lignocellulosic biomass-to-ethanol pipeline. Here, the feasibility of scaling-up the AHP process and integrating it with enzymatic hydrolysis and fermentation was studied. Corn stover (1?kg) was subjected to AHP pretreatment, hydrolyzed enzymatically, and the resulting sugars fermented to ethanol. The AHP pretreatment was performed at 0.125?g H(2) O(2) /g biomass, 22°C, and atmospheric pressure for 48?h with periodic pH readjustment. The enzymatic hydrolysis was performed in the same reactor following pH neutralization of the biomass slurry and without washing. After 48?h, glucose and xylose yields were 75% and 71% of the theoretical maximum. Sterility was maintained during pretreatment and enzymatic hydrolysis without the use of antibiotics. During fermentation using a glucose- and xylose-utilizing strain of Saccharomyces cerevisiae, all of the Glc and 67% of the Xyl were consumed in 120?h. The final ethanol titer was 13.7?g/L. Treatment of the enzymatic hydrolysate with activated carbon prior to fermentation had little effect on Glc fermentation but markedly improved utilization of Xyl, presumably due to the removal of soluble aromatic inhibitors. The results indicate that AHP is readily scalable and can be integrated with enzyme hydrolysis and fermentation. Compared to other leading pretreatments for lignocellulosic biomass, AHP has potential advantages with regard to capital costs, process simplicity, feedstock handling, and compatibility with enzymatic deconstruction and fermentation. Biotechnol. Bioeng. 2012; 109:922-931. © 2011 Wiley Periodicals, Inc. PMID:22125119

Banerjee, Goutami; Car, Suzana; Liu, Tongjun; Williams, Daniel L; Meza, Sarynna López; Walton, Jonathan D; Hodge, David B

2012-04-01

18

Impact of enzymatic and alkaline hydrolysis on CBD concentration in urine  

PubMed Central

A sensitive and specific analytical method for cannabidiol (CBD) in urine was needed to define urinary CBD pharmacokinetics after controlled CBD administration, and to confirm compliance with CBD medications including Sativex—a cannabis plant extract containing 1:1 ?9-tetrahydrocannabinol (THC) and CBD. Non-psychoactive CBD has a wide range of therapeutic applications and may also influence psychotropic smoked cannabis effects. Few methods exist for the quantification of CBD excretion in urine, and no data are available for phase II metabolism of CBD to CBD-glucuronide or CBD-sulfate. We optimized the hydrolysis of CBD-glucuronide and/or -sulfate, and developed and validated a GC-MS method for urinary CBD quantification. Solid-phase extraction isolated and concentrated analytes prior to GC-MS. Method validation included overnight hydrolysis (16 h) at 37 °C with 2,500 units ?-glucuronidase from Red Abalone. Calibration curves were fit by linear least squares regression with 1/x2 weighting with linear ranges (r2>0.990) of 2.5–100 ng/mL for non-hydrolyzed CBD and 2.5–500 ng/mL for enzyme-hydrolyzed CBD. Bias was 88.7–105.3 %, imprecision 1.4–6.4 % CV and extraction efficiency 82.5–92.7 % (no hydrolysis) and 34.3–47.0 % (enzyme hydrolysis). Enzyme-hydrolyzed urine specimens exhibited more than a 250-fold CBD concentration increase compared to alkaline and non-hydrolyzed specimens. This method can be applied for urinary CBD quantification and further pharmacokinetics characterization following controlled CBD administration. PMID:23494274

Bergamaschi, Mateus M.; Barnes, Allan; Queiroz, Regina H. C.; Hurd, Yasmin L.

2013-01-01

19

Impact of enzymatic and alkaline hydrolysis on CBD concentration in urine.  

PubMed

A sensitive and specific analytical method for cannabidiol (CBD) in urine was needed to define urinary CBD pharmacokinetics after controlled CBD administration, and to confirm compliance with CBD medications including Sativex-a cannabis plant extract containing 1:1 ?(9)-tetrahydrocannabinol (THC) and CBD. Non-psychoactive CBD has a wide range of therapeutic applications and may also influence psychotropic smoked cannabis effects. Few methods exist for the quantification of CBD excretion in urine, and no data are available for phase II metabolism of CBD to CBD-glucuronide or CBD-sulfate. We optimized the hydrolysis of CBD-glucuronide and/or -sulfate, and developed and validated a GC-MS method for urinary CBD quantification. Solid-phase extraction isolated and concentrated analytes prior to GC-MS. Method validation included overnight hydrolysis (16 h) at 37 °C with 2,500 units ?-glucuronidase from Red Abalone. Calibration curves were fit by linear least squares regression with 1/x (2) weighting with linear ranges (r(2) > 0.990) of 2.5-100 ng/mL for non-hydrolyzed CBD and 2.5-500 ng/mL for enzyme-hydrolyzed CBD. Bias was 88.7-105.3 %, imprecision 1.4-6.4 % CV and extraction efficiency 82.5-92.7 % (no hydrolysis) and 34.3-47.0 % (enzyme hydrolysis). Enzyme-hydrolyzed urine specimens exhibited more than a 250-fold CBD concentration increase compared to alkaline and non-hydrolyzed specimens. This method can be applied for urinary CBD quantification and further pharmacokinetics characterization following controlled CBD administration. PMID:23494274

Bergamaschi, Mateus M; Barnes, Allan; Queiroz, Regina H C; Hurd, Yasmin L; Huestis, Marilyn A

2013-05-01

20

Time dependent solid-state 13C NMR study on alkaline hydrolysis of polyacrylonitrile hollow fiber ultrafiltration membranes  

Microsoft Academic Search

The effects of alkaline hydrolysis on the chemical structure of polyacrylonitrile (PAN) hollow fiber ultrafiltration (UF) membrane were studied using solid-state 13C NMR spectroscopy. The PAN membrane was hydrolyzed in an NaOH solution of pH 13, which is generally used in water industry for anti-fouling treatments of UF membranes but is much weaker than the alkaline concentrations (0.5–2.5N) used so

Yong Hun Choi; Chang Min Choi; Dae Ho Choi; Younkee Paik; Byung Jae Park; Young Kil Joo; Nam Joon Kim

2011-01-01

21

Enzymatic kinetic parameters for polyfluorinated alkyl phosphate hydrolysis by alkaline phosphatase.  

PubMed

The hydrolysis kinetics of three polyfluorinated alkyl phosphate monoesters (monoPAPs), differing in fluorinated chain length, were measured using bovine intestinal alkaline phosphatase to catalyze the reaction. Kinetic values were also measured for analogous hydrogenated phosphate monoesters to elucidate the effects of the fluorinated chain on the rate of enzymatic hydrolysis. Michaelis constants (K(m)) were obtained by a competition kinetics technique in the presence of p-nitrophenyl phosphate (PNPP) using UV-vis spectroscopy. Compared with K(m) (PNPP), Michaelis constants for monoPAPs ranged from 0.9 to 2.1 compared with hydrogenated phosphates, which ranged from 4.0 to 13.0. Apparent bimolecular rate constants (k(cat)/K(m)) were determined by monitoring rates of product alcohol formation at low substrate concentrations using gas chromatography-mass spectrometry. The experimental values for k(cat)/K(m) averaged as 1.1 × 10(7) M(-1) s(-1) for monoPAPs compared with 3.8 × 10(5) M(-1) s(-1) for hexyl phosphate. This suggests that the electron-withdrawing nature of the fluorinated chain enhanced the alcohol leaving group ability. The results were used in a simple model to suggest that monoPAPs in a typical mammalian digestive tract would hydrolyze in approximately 100 s, supporting a previous study that showed its absence after a dosing study in rats. PMID:22714665

Jackson, Derek A; Mabury, Scott A

2012-09-01

22

Alkaline Hydrolysis is an Effective Treatment Technology for RDX-Contaminated Groundwater  

SciTech Connect

Kinetics and treatability of alkaline hydrolysis were investigated in batch reactor and continuous flow-stirred tank reactor (CFSTR) for remediating groundwater contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The batch system (pH 11 to 13, RDX 1 to 10 mg/L) achieved pseudo first-order RDX transformation rates in the range of 0.2 to 47.5 min-1, corresponding to 57.8 to 0.2 hrs of half-life period, respectively. In the CFSTR system (pH 11 to 11.9, HRT 0.54 to 2 days), the best alkaline RDX transformation was achieved a 99% RDX removal with the longest HRT and the highest reaction pH. Formate ({approx}2 M/M RDXremoved) and nitrite ({approx}0.2 M/M RDXremoved) were produced as the major hydrolysates, indicative of a simultaneous transformation mechanism by RDX ring cleavage and ring nitrogen elimination. The net OH- demand was found to be 1.5, 390 and 130 M OH-/M RDXremoved at the pH of 11.9, 11.5 and 11.0, respectively, in the CFSTR system.

Hqang, Snagchul; Felt, Deborah R.; Bouwer, Edward J.; Brooks, Michael C.; Larson, Steven L.; Davis, Jeffrey L.

2003-03-26

23

Probing the Origins of Catalytic Discrimination between Phosphate and Sulfate Monoester Hydrolysis: Comparative Analysis of Alkaline  

E-print Network

Probing the Origins of Catalytic Discrimination between Phosphate and Sulfate Monoester Hydrolysis phosphatase (AP) catalyzes both phos- phate and sulfate monoester hydrolysis reactions with a 1010 - fold preference for phosphate monoester hydrolysis, despite the similarity between these reactions

Herschlag, Dan

24

Alkaline Hydrolysis/Polymerization of 2,4,6-Trinitrotoluene: Characterization of Products by 13C and 15N NMR  

USGS Publications Warehouse

Alkaline hydrolysis has been investigated as a nonbiological procedure for the destruction of 2,4,6-trinitrotoluene (TNT) in explosives contaminated soils and munitions scrap. Nucleophilic substitutions of the nitro and methyl groups of TNT by hydroxide ion are the initial steps in the alkaline degradation of TNT. Potential applications of the technique include both in situ surface liming and ex situ alkaline treatment of contaminated soils. A number of laboratory studies have reported the formation of an uncharacterized polymeric material upon prolonged treatment of TNT in base. As part of an overall assessment of alkaline hydrolysis as a remediation technique, and to gain a better understanding of the chemical reactions underlying the hydrolysis/polymerization process, the soluble and precipitate fractions of polymeric material produced from the calcium hydroxide hydrolysis of unlabeled and 15N-labeled TNT were analyzed by elemental analysis and 13C and 15N nuclear magnetic resonance spectroscopy. Spectra indicated that reactions leading to polymerization included nucleophilic displacement of nitro groups by hydroxide ion, formation of ketone, carboxyl, alcohol, ether, and other aliphatic carbons, conversion of methyl groups to diphenyl methylene carbons, and recondensation of aromatic amines and reduced forms of nitrite, including ammonia and possibly hydroxylamine, into the polymer. Compared to the distribution of carbons in TNT as 14% sp 3- and 86% sp2-hybridized, the precipitate fraction from hydrolysis of unlabeled TNT contained 33% sp3- and 67% sp 2-hybridized carbons. The concentration of nitrogen in the precipitate was 64% of that in TNT. The 15N NMR spectra showed that, in addition to residual nitro groups, forms of nitrogen present in the filtrate and precipitate fractions include aminohydroquinone, primary amide, indole, imine, and azoxy, among others. Unreacted nitrite was recovered in the filtrate fraction. The toxicities and susceptibilities to microbial or chemical degradation of the polymeric materials remain unknown.

Thorn, K.A.; Thorne, P.G.; Cox, L.G.

2004-01-01

25

Coupling alkaline pre-extraction with alkaline-oxidative post-treatment of corn stover to enhance enzymatic hydrolysis and fermentability  

PubMed Central

Background A two-stage chemical pretreatment of corn stover is investigated comprising an NaOH pre-extraction followed by an alkaline hydrogen peroxide (AHP) post-treatment. We propose that conventional one-stage AHP pretreatment can be improved using alkaline pre-extraction, which requires significantly less H2O2 and NaOH. To better understand the potential of this approach, this study investigates several components of this process including alkaline pre-extraction, alkaline and alkaline-oxidative post-treatment, fermentation, and the composition of alkali extracts. Results Mild NaOH pre-extraction of corn stover uses less than 0.1 g NaOH per g corn stover at 80°C. The resulting substrates were highly digestible by cellulolytic enzymes at relatively low enzyme loadings and had a strong susceptibility to drying-induced hydrolysis yield losses. Alkaline pre-extraction was highly selective for lignin removal over xylan removal; xylan removal was relatively minimal (~20%). During alkaline pre-extraction, up to 0.10 g of alkali was consumed per g of corn stover. AHP post-treatment at low oxidant loading (25 mg H2O2 per g pre-extracted biomass) increased glucose hydrolysis yields by 5%, which approached near-theoretical yields. ELISA screening of alkali pre-extraction liquors and the AHP post-treatment liquors demonstrated that xyloglucan and ?-glucans likely remained tightly bound in the biomass whereas the majority of the soluble polymeric xylans were glucurono (arabino) xylans and potentially homoxylans. Pectic polysaccharides were depleted in the AHP post-treatment liquor relative to the alkaline pre-extraction liquor. Because the already-low inhibitor content was further decreased in the alkaline pre-extraction, the hydrolysates generated by this two-stage pretreatment were highly fermentable by Saccharomyces cerevisiae strains that were metabolically engineered and evolved for xylose fermentation. Conclusions This work demonstrates that this two-stage pretreatment process is well suited for converting lignocellulose to fermentable sugars and biofuels, such as ethanol. This approach achieved high enzymatic sugars yields from pretreated corn stover using substantially lower oxidant loadings than have been reported previously in the literature. This pretreatment approach allows for many possible process configurations involving novel alkali recovery approaches and novel uses of alkaline pre-extraction liquors. Further work is required to identify the most economical configuration, including process designs using techno-economic analysis and investigating processing strategies that economize water use. PMID:24693882

2014-01-01

26

Inorganic nanofibers with tailored placement of nanocatalysts for hydrogen production via alkaline hydrolysis of glucose  

NASA Astrophysics Data System (ADS)

Monoaxial silica nanofibers containing iron species as well as coaxial nanofibers with a pure silica core and a silica shell containing high concentrations of iron nanocrystals were fabricated via electrospinning precursor solutions, followed by thermal treatment. Tetraethyl-orthosilicate (TEOS) and iron nitrate (Fe(NO3)3) were used as the precursors for the silica and iron phases, respectively. Thermal treatments of as-spun precursor fibers were applied to generate nanocrystals of iron with various oxidation states (pure iron and hematite). Scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to probe the fiber morphology and crystal structures. The results indicated that the size, phase, and placement of iron nanocrystals can be tuned by varying the precursor concentration, thermal treatment conditions, and processing scheme. The resulting nanofiber/metal systems obtained via both monoaxial and coaxial electrospinning were applied as catalysts to the alkaline hydrolysis of glucose for the production of fuel gas. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and bulk weight change in a furnace with residual gas analysis (RGA) were used to evaluate the performance of the catalysts for various ratios of both Fe to Si, and catalyst to glucose, and the oxidation state of the iron nanocrystals. The product gas is composed of mostly H2 (>96 mol%) and CH4 with very low concentrations of CO2 and CO. Due to the clear separation of reaction temperature for H2 and CH4 production, pure hydrogen can be obtained at low reaction temperatures. Our coaxial approach demonstrates that placing the iron species selectively near the fiber surface can lead to two to three fold reduction in catalytic consumption compared to the monoaxial fibers with uniform distribution of catalysts.

Hansen, Nathaniel S.; Ferguson, Thomas E.; Panels, Jeanne E.; Alissa Park, Ah-Hyung; Lak Joo, Yong

2011-08-01

27

Inorganic nanofibers with tailored placement of nanocatalysts for hydrogen production via alkaline hydrolysis of glucose.  

PubMed

Monoaxial silica nanofibers containing iron species as well as coaxial nanofibers with a pure silica core and a silica shell containing high concentrations of iron nanocrystals were fabricated via electrospinning precursor solutions, followed by thermal treatment. Tetraethyl-orthosilicate (TEOS) and iron nitrate (Fe(NO(3))(3)) were used as the precursors for the silica and iron phases, respectively. Thermal treatments of as-spun precursor fibers were applied to generate nanocrystals of iron with various oxidation states (pure iron and hematite). Scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to probe the fiber morphology and crystal structures. The results indicated that the size, phase, and placement of iron nanocrystals can be tuned by varying the precursor concentration, thermal treatment conditions, and processing scheme. The resulting nanofiber/metal systems obtained via both monoaxial and coaxial electrospinning were applied as catalysts to the alkaline hydrolysis of glucose for the production of fuel gas. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and bulk weight change in a furnace with residual gas analysis (RGA) were used to evaluate the performance of the catalysts for various ratios of both Fe to Si, and catalyst to glucose, and the oxidation state of the iron nanocrystals. The product gas is composed of mostly H(2) (>96 mol%) and CH(4) with very low concentrations of CO(2) and CO. Due to the clear separation of reaction temperature for H(2) and CH(4) production, pure hydrogen can be obtained at low reaction temperatures. Our coaxial approach demonstrates that placing the iron species selectively near the fiber surface can lead to two to three fold reduction in catalytic consumption compared to the monoaxial fibers with uniform distribution of catalysts. PMID:21772071

Hansen, Nathaniel S; Ferguson, Thomas E; Panels, Jeanne E; Park, Ah-Hyung Alissa; Joo, Yong Lak

2011-08-12

28

Effect of anatomical fractionation on the enzymatic hydrolysis of acid and alkaline pretreated corn stover  

Microsoft Academic Search

Due to concerns with biomass collection systems and soil sustainability there are opportunities to investigate the optimal plant fractions to collect for conversion. An ideal feedstock would require a low severity pretreatment to release a maximum amount of sugar during enzymatic hydrolysis. Corn stover fractions were separated manually and analyzed for glucan, xylan, acid soluble lignin, acid insoluble lignin, and

K. B. Duguid; M. D. Montross; C. W. Radtke; C. L. Crofcheck; L. M. Wendt; S. A. Shearer

2009-01-01

29

Investigation of Unexpected Reaction Intermediates in the Alkaline Hydrolysis of Methyl 3,5-Dinitrobenzoate  

ERIC Educational Resources Information Center

An experimental project aimed at identifying stable reaction intermediates is described. Initially, the studied reaction appears to involve the simple hydrolysis, by aqueous sodium hydroxide, of methyl 3,5-dinitrobenzoate dissolved in dimethyl sulfoxide. On mixing the substrates, however, the reaction mixture unexpectedly turns an intense red in…

Silva, Clesia C.; Silva, Ricardo O.; Navarro, Daniela M. A. F.; Navarro, Marcelo

2009-01-01

30

Comprehensive investigations of kinetics of alkaline hydrolysis of TNT (2,4,6-trinitrotoluene), DNT (2,4-dinitrotoluene), and DNAN (2,4-dinitroanisole).  

PubMed

Combined experimental and computational techniques were used to analyze multistep chemical reactions in the alkaline hydrolysis of three nitroaromatic compounds: 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), and 2,4-dinitroanisole (DNAN). The study reveals common features and differences in the kinetic behavior of these compounds. The analysis of the predicted pathways includes modeling of the reactions, along with simulation of UV-vis spectra, experimental monitoring of reactions using LC/MS techniques, development of the kinetic model by designing and solving the system of differential equations, and obtaining computationally predicted kinetics for decay and accumulation of reactants and products. Obtained results suggest that DNT and DNAN are more resistant to alkaline hydrolysis than TNT. The direct substitution of a nitro group by a hydroxide represents the most favorable pathway for all considered compounds. The formation of Meisenheimer complexes leads to the kinetic first-step intermediates in the hydrolysis of TNT. Janovsky complexes can also be formed during hydrolysis of TNT and DNT but in small quantities. Methyl group abstraction is one of the suggested pathways of DNAN transformation during alkaline hydrolysis. PMID:25083594

Sviatenko, Liudmyla; Kinney, Chad; Gorb, Leonid; Hill, Frances C; Bednar, Anthony J; Okovytyy, Sergiy; Leszczynski, Jerzy

2014-09-01

31

EFFECT OF ANATOMICAL FRACTIONATION ON THE ENZYMATIC HYDROLYSIS OF ACID AND ALKALINE PRETREATED CORN STOVER  

SciTech Connect

Due to concerns with biomass collection systems and soil sustainability there are opportunities to investigate the optimal plant fractions to collect for conversion. An ideal feedstock would require low severity pretreatment to release a maximum amount of sugar during enzymatic hydrolysis. Corn stover fractions were separated by hand and analyzed for glucan, xylan, acid soluble lignin, acid insoluble lignin, and ash composition. The stover fractions were also pretreated with either 0, 0.4, or 0.8% NaOH for 2 hours at room temperature, washed, autoclaved and saccharified. In addition, acid pretreated samples underwent simultaneous saccharification and fermentation (SSF) to ethanol. In general, the two pretreatments produced similar trends with cobs, husks, and leaves responding best to the pretreatments, the tops of stalks responding slightly less, and the bottom of the stalks responding the least. For example, corn husks pretreated with 0.8% NaOH released over 90% (standard error of 3.8%) of the available glucan, while only 45% (standard error of 1.1%) of the glucan was produced from identically treated stalk bottoms. Estimates of the theoretical ethanol yield using acid pretreatment followed by SSF were 65% (standard error of 15.9%) for husks and 29% (standard error of 1.8%) for stalk bottoms. This suggests that integration of biomass collection systems to remove sustainable feedstocks could be integrated with the processes within a biorefinery to minimize overall ethanol production costs.

K. B. Duguid; M. D. Montross; C. W. Radtke; C. L. Crofcheck; L. M. Wendt; S. A. Shearer

2009-11-01

32

Electrolytic redox and electrochemical generated alkaline hydrolysis of hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) in sand columns.  

PubMed

Sand-packed horizontal flow columns (5 cm i.d. x 65 cm)l were used in laboratory experiments to simulate in situ electrolytic and alkaline hybrid treatment zone for aqueous phase decomposition of RDX. An upgradient cathode and downgradient anode, spaced 35 cm apart were used to create alkaline reducing conditions followed by oxic, acidic conditions to degrade RDX by combination of alkaline hydrolysis and direct electrolysis. A preliminary experiment (25 mg/L RDX influent) with seepage velocity of 30.5 cm/day and current density of 9.9 A/m2 was used to determine the treatment feasibility and the aqueous products of RDX decomposition. Three additional column experiments (0.5 mg/L RDX influent) under the same conditions as the preliminary column were used to observe the treatment process repeatability and the alkaline treatment zone development. The results demonstrated approximately 95% decomposition of RDX in the column with an applied current density of 9.9 A/m2. Aqueous end-products formate, nitrite, and nitrate were detected in the effluent. Approximately 75% of the RDX was destroyed near the cathode, presumably by electrolysis, with 23% decomposed downstream of the cathode by alkaline hydrolysis. The preliminary column pseudo first order alkaline hydrolysis rate coefficient of 10.7 x 10(-3) min(-1) was used to estimate a treatment zone length less than 100 cm for RDX treatment below the EPA drinking water lifetime health advisory of 0.002 mg/L. PMID:19746729

Gent, David B; Wani, Altaf H; Davis, Jeffrey L; Alshawabkeh, Akram

2009-08-15

33

The use of alkaline hydrolysis as a novel strategy for chloroform remediation: the feasibility of using construction wastes and evaluation of carbon isotopic fractionation.  

PubMed

Laboratory and field-scale pilot experiments were performed to evaluate the feasibility of chloroform degradation by alkaline hydrolysis and the potential of ?(13)C values to assess this induced reaction process at contaminated sites. In batch experiments, alkaline conditions were induced by adding crushed concrete (pH 12.33 ± 0.07), a filtered concrete solution (pH 12.27 ± 0.04), a filtered cement solution (pH 12.66 ± 0.02) and a pH 12 buffer solution (pH 11.92 ± 0.11). The resulting chloroform degradation after 28 days was 94, 96, 99, and 72%, respectively. The experimental data were described using a pseudo-first-order kinetic model, resulting in pseudo-first-order rate constant values of 0.10, 0.12, 0.20, and 0.05 d(-1), respectively. Furthermore, the significant chloroform carbon isotopic fractionation associated with alkaline hydrolysis of chloroform (-53 ± 3‰) and its independence from pH in the admittedly limited tested pH range imply a great potential for the use of ?(13)C values for in situ monitoring of the efficacy of remediation approaches based on alkaline hydrolysis. The carbon isotopic fractionation obtained at the lab scale allowed the calculation of the percentage of chloroform degradation in field-scale pilot experiments where alkaline conditions were induced in two recharge water interception trenches filled with concrete-based construction wastes. A maximum of approximately 30-40% of chloroform degradation was achieved during the two studied recharge periods. Although further research is required, the treatment of chloroform in groundwater through the use of concrete-based construction wastes is proposed. This strategy would also imply the recycling of construction and demolition wastes for use in value-added applications to increase economic and environmental benefits. PMID:24410407

Torrentó, Clara; Audí-Miró, Carme; Bordeleau, Geneviève; Marchesi, Massimo; Rosell, Mònica; Otero, Neus; Soler, Albert

2014-02-01

34

Mechanisms and Kinetics of Alkaline Hydrolysis of the Energetic Nitroaromatic Compounds 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN)  

SciTech Connect

The environmental impacts of energetic compounds can be minimized through the design and selection of new energetic materials with favorable fate properties. Building predictive models to inform this process, however, is difficult because of uncertainties and complexities in some major fate-determining transformation reactions such as the alkaline hydrolysis of energetic nitroaromatic compounds (NACs). Prior work on the mechanisms of the reaction between NACs and OH? has yielded inconsistent results. In this study, the alkaline hydrolysis of 2,4,6-trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN) were investigated with coordinated experimental kinetic measurements and molecular modeling calculations. For TNT, the results suggest reversible formation of an initial product, which is likely either a Meisenheimer complex or a TNT anion formed by abstraction of a methyl proton by OH?. For DNAN, the results suggest that a Meisenheimer complex is an intermediat in the formation of 2,4-dinitrophenolate. Despite these advances, the remaining uncertainties in the mechanisms of these reactions - and potential variability between the hydrolysis mechanisms for different NACs - mean that it is not yet possible to generalize the results into predictive models (e.g., quantitative structure-activity relationships, QSARs) for hydrolysis of other NACs.

Salter-Blanc, Alexandra; Bylaska, Eric J.; Ritchie, Julia J.; Tratnyek, Paul G.

2013-07-02

35

Kinetic isotope effects and intermediate formation for the aqueous alkaline homogeneous hydrolysis of 1,3,5-triaza-1,3,5-trinitrocyclohexane (RDX)  

Microsoft Academic Search

The kinetics and activation parameters for the aqueous alkaline hydrolysis of hexaproteo (RDX-hâ) and hexadeuterio (RDX-dâ) 1,3,5-triaza-1,3,5-trinitrocyclohexanes with hydroxide ion concentrations between 0.020 and 0.25 M and temperatures of 25.0, 35.0, and 45.0°C have been investigated. Both RDX-hâ and RDX-dâ showed good second-order rate constants for the expression, -d(RDX)\\/dt = kâ(OH⁻)(RDX) = kâ(RDX), where k⁠is the first-order rate constant

John C. Hoffsommer; Donald A. Kubose; Donald J. Glover

1977-01-01

36

Probing the origins of catalytic discrimination between phosphate and sulfate monoester hydrolysis: comparative analysis of alkaline phosphatase and protein tyrosine phosphatases.  

PubMed

Catalytic promiscuity, the ability of enzymes to catalyze multiple reactions, provides an opportunity to gain a deeper understanding of the origins of catalysis and substrate specificity. Alkaline phosphatase (AP) catalyzes both phosphate and sulfate monoester hydrolysis reactions with a ?10(10)-fold preference for phosphate monoester hydrolysis, despite the similarity between these reactions. The preponderance of formal positive charge in the AP active site, particularly from three divalent metal ions, was proposed to be responsible for this preference by providing stronger electrostatic interactions with the more negatively charged phosphoryl group versus the sulfuryl group. To test whether positively charged metal ions are required to achieve a high preference for the phosphate monoester hydrolysis reaction, the catalytic preference of three protein tyrosine phosphatases (PTPs), which do not contain metal ions, were measured. Their preferences ranged from 5 × 10(6) to 7 × 10(7), lower than that for AP but still substantial, indicating that metal ions and a high preponderance of formal positive charge within the active site are not required to achieve a strong catalytic preference for phosphate monoester over sulfate monoester hydrolysis. The observed ionic strength dependences of kcat/KM values for phosphate and sulfate monoester hydrolysis are steeper for the more highly charged phosphate ester with both AP and the PTP Stp1, following the dependence expected based on the charge difference of these two substrates. However, the dependences for AP were not greater than those of Stp1 and were rather shallow for both enzymes. These results suggest that overall electrostatics from formal positive charge within the active site is not the major driving force in distinguishing between these reactions and that substantial discrimination can be attained without metal ions. Thus, local properties of the active site, presumably including multiple positioned dipolar hydrogen bond donors within the active site, dominate in defining this reaction specificity. PMID:25299936

Andrews, Logan D; Zalatan, Jesse G; Herschlag, Daniel

2014-11-01

37

Chemical state of heterocyclic aromatic amines in grilled beef: evaluation by in vitro digestion model and comparison of alkaline hydrolysis and organic solvent for extraction.  

PubMed

During grilling of the roast beef the following heterocyclic aromatic amines were found: IQ=200.6 ng 100g(-1), MeIQx=719.8 ng 100 g(-1), MeIQ=532.9 ng 100g(-1), 4.8-diMeIQx=755.4 ng 100 g(-1), norharmane=507.0 ng 100 g(-1), harmane=1952.6 ng 100 g(-1), Phe-P 1=263.7 ng 100 g(-1), Trp-P 2=559.2 ng 100 g(-1), PhIP=1179.8 ng 100 g(-1) and A?C=51.7 ng 100g(-1). Their content was tested by using the method based on alkaline hydrolysis of the sample and the method based on solvent extraction of the grilled meat samples at different temperatures (without hydrolysis). The study showed that the heterocyclic aromatic amines produced during the grilling of beef are in a free form and chemically or physico-chemically bonded. The chemical forms of HAA formed in food have never been studied. For the purpose of the partial confirmation that HAA may be chemically or physico-chemically bonded, grilled beef samples were digested in vitro in model segments of the human digestive tract. Digestive enzymes, particularly proteolytic enzymes caused a statistically significant increase of free HAA determined by using solvent extraction without prior chemical hydrolysis of the sample. PMID:24120899

Szterk, Arkadiusz

2013-12-01

38

The alkaline hydrolysis of nucleic acid for removal of RNA associated fluorescence in phenantridium related flow through cytofluorometry  

Microsoft Academic Search

Flow through microfluorometry of phenantridium and fluoresceinisothiocyanate stained HeLa cells showed the absence of extranuclear RNA related fluorescence after prolonged hydrolysis of cells in ethanolic barium hydroxide. DNA distribution were as good as in RNAse treated samples. Distribution pattern of cellular protein\\/DNA ratios yielded greater resolution power than those after RNAse digestion. The cellular protein content has not been affected.

Michael Stöhr; Liliane Petrova

1975-01-01

39

Effect of organic matter and urease inhibitors on urea hydrolysis and immobilization of urea nitrogen in an alkaline soil  

Microsoft Academic Search

Laboratory incubation experiments with 15N-labelled urea were conducted on a Aquic Udifluvent Belgian soil amended with barley straw, in, order to study the influence of three urease inhibitors, hydroquinone, phenyl phosphorodiamidate and N-(n-butyl) phosphorothioic triamide on urea hydrolysis and N transformations. The results demonstrated that the urea was hydrolyzed more rapidly when the soil was amended with ground barley straw.

Wang Zhengping; O. Van Cleemput; Li Liantie; L. Baert

1991-01-01

40

Determination of Tryptophan with HPLC after Alkaline Hydrolysis in Autoclave using ?-methyl-tryptophan as Internal Standard  

Microsoft Academic Search

A method for determination of tryptophan in feeding stuffs is described. The hydrolysis is carried out on a sample containing 10 mg nitrogen using 25 ml NaOH 4.2 mol\\/l at 110°C for 16 hours in an autoclave. ?-methyl-tryptophan is used as internal standard. The tryptophan and the internal standard are determined by using HPLC with fluorescence detection. When analysing three

Steen Bech-Andersen

1991-01-01

41

Unimolecular and hydrolysis channels for the detachment of water from microsolvated alkaline earth dication (Mg2+, Ca2+, Sr2+, Ba2+) clusters  

SciTech Connect

We examine theoretically the three channels that are associated with the detachment of a single water molecule from the aqueous clusters of the alkaline earth dications, [M(H2O)n]2+, M = Mg, Ca, Sr, Ba, n ? 6. These are the unimolecular water loss (M2+(H2O)n-1 + H2O) and the two hydrolysis channels resulting to the loss of hydronium ([MOH(H2O)n-2]+ + H3O+) and Zundel ([MOH(H2O)n-3]+ + H3O+(H2O)) cations. The Potential Energy Curves (PECs) corresponding to those three channels were constructed at the Møller-Plesset second order perturbation (MP2) level of theory with basis sets of double- and triple-? quality. We furthermore investigated the water and hydronium loss channels from the mono-hydroxide water clusters with up to four water molecules, [MOH(H2O)n]+, 1 ? n ? 4. Our results indicate the preference of the hydronium loss and possibly the Zundel cation loss channels for the smallest size clusters, whereas the unimolecular water loss channel is preferred for the larger ones as well as the mono-hydroxide clusters. Although the charge separation (hydronium and Zundel cation loss) channels produce more stable products when compared to the ones for the unimolecular water loss, they also require the surmounting of high energy barriers, a fact that makes the experimental observation of fragments related to these hydrolysis channels difficult.

Miliordos, Evangelos; Xantheas, Sotiris S.

2014-02-07

42

The hydrolysis of polyimides  

NASA Technical Reports Server (NTRS)

Thermal polymerization of aspartic acid produces a polysuccinimide (I), a chain of aspartoyl residues. An investigation was made of the alkaline hydrolysis of the imide rings of (I) which converts the polyimide to a polypeptide. The alkaline hydrolysis of polyimides can be expected to be kinetically complex due to increasing negative charge generated by carboxylate groups. For this reason, a diimide, phthaloyl-DL-aspartoyl-beta-alanine (IIA) was synthesized for a progressive study of the hydrolysis of polyimides. In addition, this diimide (IIA) can be related to thalidomide and might be expected to exhibit similar reactivity during hydrolysis of the phthalimide ring.

Hoagland, P. D.; Fox, S. W.

1973-01-01

43

Formulation of enzyme blends to maximize the hydrolysis of alkaline peroxide pretreated alfalfa hay and barley straw by rumen enzymes and commercial cellulases  

PubMed Central

Background Efficient conversion of lignocellulosic biomass to fermentable sugars requires the synergistic action of multiple enzymes; consequently enzyme mixtures must be properly formulated for effective hydrolysis. The nature of an optimal enzyme blends depends on the type of pretreatment employed as well the characteristics of the substrate. In this study, statistical experimental design was used to develop mixtures of recombinant glycosyl hydrolases from thermophilic and anaerobic fungi that enhanced the digestion of alkaline peroxide treated alfalfa hay and barley straw by mixed rumen enzymes as well as commercial cellulases (Accelerase 1500, A1500; Accelerase XC, AXC). Results Combinations of feruloyl and acetyl xylan esterases (FAE1a; AXE16A_ASPNG), endoglucanase GH7 (EGL7A_THITE) and polygalacturonase (PGA28A_ASPNG) with rumen enzymes improved straw digestion. Inclusion of pectinase (PGA28A_ASPNG), endoxylanase (XYN11A_THITE), feruloyl esterase (FAE1a) and ?-glucosidase (E-BGLUC) with A1500 or endoglucanase GH7 (EGL7A_THITE) and ?-xylosidase (E-BXSRB) with AXC increased glucose release from alfalfa hay. Glucose yield from straw was improved when FAE1a and endoglucanase GH7 (EGL7A_THITE) were added to A1500, while FAE1a and AXE16A_ASPNG enhanced the activity of AXC on straw. Xylose release from alfalfa hay was augmented by supplementing A1500 with E-BGLUC, or AXC with EGL7A_THITE and XYN11A_THITE. Adding arabinofuranosidase (ABF54B_ASPNG) and esterases (AXE16A_ASPNG; AXE16B_ASPNG) to A1500, or FAE1a and AXE16A_ASPNG to AXC enhanced xylose release from barley straw, a response confirmed in a scaled up assay. Conclusion The efficacy of commercial enzyme mixtures as well as mixed enzymes from the rumen was improved through formulation with synergetic recombinant enzymes. This approach reliably identified supplemental enzymes that enhanced sugar release from alkaline pretreated alfalfa hay and barley straw. PMID:24766728

2014-01-01

44

PHTHALATE ESTER HYDROLYSIS: LINEAR FREE ENERGY RELATIONSHIPS  

EPA Science Inventory

Alkaline hydrolysis rate constants were measured for dimethyl, diethyl, di-n-butyl, di-iso-butyl, and di-(2-ethylhexyl) phthalate esters in water. A linear free energy relationship (LFER) was established for estimating alkaline hydrolysis rate constants for other phthalate esters...

45

Inclusion of the insecticide fenitrothion in dimethylated-?-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution.  

PubMed

An anhydrous 1:1 crystalline inclusion complex between the organophosphorus insecticide fenitrothion [O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate] and the host compound heptakis(2,6-di-O-methyl)-?-cyclodextrin (DIMEB) was prepared and its structure elucidated by single-crystal X-ray diffraction. This revealed two independent host molecules in the asymmetric unit. In one of these, the cavity is occupied by two disordered guest components (distinguishable as rotamers with respect to the P-OAr bond) while in the other, three distinct guest components with site-occupancies 0.44, 0.29 and 0.27 appear, the last having a reversed orientation relative to all the other components. Kinetic studies of the alkaline hydrolysis of fenitrothion in the presence of DIMEB showed a remarkable reduction of 84% in the rate of this reaction relative to that for the free substrate, a value exceeding those previously attained with the native hosts, ?- and ?-cyclodextrin, and fully methylated ?-cyclodextrin. PMID:23400042

Cruickshank, Dyanne L; Rougier, Natalia M; Vico, Raquel V; Bourne, Susan A; Buján, Elba I; Caira, Mino R; de Rossi, Rita H

2013-01-01

46

ABIOTIC HYDROLYSIS OF SORBED PESTICIDES  

EPA Science Inventory

The hydrolysis of pesticides that are sorbed to sterilized natural sediments has been investigated in aqueous systems at acid, neutral and alkaline pH's. The results show that the rate constants of pH independent ('neutral') hydrolyses are the same within experimental uncertainti...

47

Alkalinity Protocol  

NSDL National Science Digital Library

'The purpose of the resource is to meaure the alkalinity of a water sample. Students will use an alkalinity kit to measure the alkalinity in the water at their hydrology site. The exact procedure depends on the instructions in the alkalinity kit used.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

48

Alkalinity Protocol  

NSDL National Science Digital Library

This site from GLOBE describes an exercise in which students learn the correct way to measure the alkalinity of water. Topics include definitions of alkaline and pH, and the importance of alkalinity in buffering acidic additions to water. Also included are lab and field guides, and examples of student research.

Globe

49

CAPTAN HYDROLYSIS  

EPA Science Inventory

Captan (N-(trichloromethylthio)-4-cyclohexene-1,2-dicarboximide) undergoes hydrolysis readily in water with a maximum half-life of 710 min. Over the pH range 2-6, the reaction is pH independent and the pseudo-first-order rate constant is (1.8 + or - 0.1) x 10 to the -5th power/s....

50

Enzymatic hydrolysis of cellulose  

SciTech Connect

This book reviews the theory and application of enzymatic hydrolysis of cellulosic biomass; with implications for genetic engineering techniques. State of the art and potential industrial processes are detailed, including high productivity fermentation systems for the production of ethanol. Contents: Theory of Enzymatic Hydrolysis; Production of Cellulase and Xylanase; Hydrolysis of Agricultural Residues; Enzymatic Hydrolysis Processes; High Productivity Ethanol Fermentation; Ethanol Economics.

Wilke, C.R.

1983-01-01

51

CARBARYL, PROPHAM AND CHLORPROPHAM: A COMPARISON OF THE RATES OF HYDROLYSIS AND PHOTOLYSIS WITH THE RATE OF BIOLYSIS  

EPA Science Inventory

Alkaline hydrolysis half-lives, based on second-order alkaline hydrolysis rate constants, for carbaryl, propham (IPC), and chlorpropham (CIPC) at pH 9 (27 degrees) are 0.15>1 x 10 to the 4th power days, and >1 x 10 to the 4th power days, respectively. The direct photolysis half-l...

52

The hydrolysis of carbonyl sulfide at low temperature: a review.  

PubMed

Catalytic hydrolysis technology of carbonyl sulfide (COS) at low temperature was reviewed, including the development of catalysts, reaction kinetics, and reaction mechanism of COS hydrolysis. It was indicated that the catalysts are mainly involved metal oxide and activated carbon. The active ingredients which can load on COS hydrolysis catalyst include alkali metal, alkaline earth metal, transition metal oxides, rare earth metal oxides, mixed metal oxides, and nanometal oxides. The catalytic hydrolysis of COS is a first-order reaction with respect to carbonyl sulfide, while the reaction order of water changes as the reaction conditions change. The controlling steps are also different because the reaction conditions such as concentration of carbonyl sulfide, reaction temperature, water-air ratio, and reaction atmosphere are different. The hydrolysis of carbonyl sulfide is base-catalyzed reaction, and the force of the base site has an important effect on the hydrolysis of carbonyl sulfide. PMID:23956697

Zhao, Shunzheng; Yi, Honghong; Tang, Xiaolong; Jiang, Shanxue; Gao, Fengyu; Zhang, Bowen; Zuo, Yanran; Wang, Zhixiang

2013-01-01

53

Chemical theory for linear alkaline flooding  

SciTech Connect

A simple equilibrium chemical model is presented for continuous, linear, alkaline waterflooding of acid oils. The unique feature of the theory is that the chemistry of the acid hydrolysis to produce surfactants is included, but only for a single acid species. Since the surface-active agent is produced in situ, a continuous alkaline flood behaves similar to a displacement with a surfactant pulse. This surfactant-pulse behavior strands otherwise mobile oil. New, experimental tertiary caustic displacements are presented for Ranger-zone oil in Wilmington sands. Tertiary oil recovery is observed once mobility control is established. 31 refs.

deZabala, E.F.; Vislocky, J.M.; Rubin, E.; Radke, C.J.

1982-04-01

54

Homogeneous hydrolysis rate constants for selected chlorinated methanes, ethanes, ethenes, and propanes  

Microsoft Academic Search

Hydrolysis rate constants of 18 chlorinated methanes, ethanes, ethenes, and propanes were measured in dilute aqueous solutions within the temperature range of 0 to 180 C and at pH values of 3 to 14. Arrhenius parameters were determined for both neutral and alkaline hydrolysis reactions. Reactivity of these compounds in basic solutions increases in accord with the expected acidity of

Peter M. Jeffers; Lisa M. Ward; Lisa M. Woytowitch; N. Lee Wolfe

1989-01-01

55

Hydrolysis in supercritical water  

SciTech Connect

Reaction of guaiacol (o-methoxyphenol) in supercritical water and with added salts showed its hydrolysis to catechol (o-hydroxyphenol) and methanol to be through a polar transition state. Correlation of the reaction kinetics following a modified Herbrandson analysis provided a quantitative summary of the greater polarity of the hydrolysis transition state relative to the hydrolysis reactants. Salt addition further shifted the transition-state equilibrium toward the transition-state species.

Huppert, G.L.; Wu, B.C.; Townsend, S.H.; Klein, M.T.; Paspek, S.C.

1989-02-01

56

Reaction pathways and free energy profiles for spontaneous hydrolysis of urea and tetramethylurea: Unexpected substituent effects  

PubMed Central

It has been difficult to directly measure the spontaneous hydrolysis rate of urea and, thus, 1,1,3,3-tetramethylurea (Me4U) was used as a model to determine the “experimental” rate constant for urea hydrolysis. The use of Me4U was based on an assumption that the rate of urea hydrolysis should be 2.8 times that of Me4U hydrolysis because the rate of acetamide hydrolysis is 2.8 times that of N,N-dimethyl-acetamide hydrolysis. The present first-principles electronic-structure calculations on the competing non-enzymatic hydrolysis pathways have demonstrated that the dominant pathway is the neutral hydrolysis via the CN addition for both urea (when pH<~11.6) and Me4U (regardless of pH), unlike the non-enzymatic hydrolysis of amides where alkaline hydrolysis is dominant. Based on the computational data, the substituent shift of free energy barrier calculated for the neutral hydrolysis is remarkably different from that for the alkaline hydrolysis, and the rate constant for the urea hydrolysis should be ~1.3×109-fold lower than that (4.2×10?12 s?1) measured for the Me4U hydrolysis. As a result, the rate enhancement and catalytic proficiency of urease should be 1.2×1025 and 3×1027 M?1, respectively, suggesting that urease surpasses proteases and all other enzymes in its power to enhance the rate of reaction. All of the computational results are consistent with available experimental data for Me4U, suggesting that the computational prediction for urea is reliable. PMID:24097048

Yao, Min; Tu, Wenlong; Chen, Xi; Zhan, Chang-Guo

2013-01-01

57

Alkaline phosphatase activity of water column fractions and seagrass in a tropical carbonate estuary, Florida Bay  

E-print Network

) requirements by producing hydrolytic enzymes such as alkaline phosphatase (AP) to sequester organic P Keywords: alkaline phosphatase activity phosphorus cyanobacteria Florida Bay enzyme hydrolysis size fractions (>1.2 and 0.2­1.2 mm) and freely dissolved enzymes (

Koch-Rose, Marguerite

58

Contribution of hydrolysis in the abiotic attenuation of RDX and HMX in coastal waters.  

PubMed

Sinking of military ships, dumping of munitions during the two World Wars, and military training have resulted in the undersea deposition of numerous unexploded ordnances (UXOs). Leaching of energetic compounds such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) from these UXOs may cause adverse ecological effects so that the long-term fate of these chemicals in the sea should be known. The present study assesses the contribution of alkaline hydrolysis into the natural attenuation of RDX and HMX in coastal waters. Alkaline hydrolysis rates were shown to be unaffected by the presence of sodium chloride, the most common component in marine waters. Kinetic parameters (E(a), ln A, k(2)) quantified for the alkaline hydrolysis of RDX and HMX in deionized water (30-50 degrees C, pH 10-12) agreed relatively well with abiotic degradation rates determined in sterilized natural coastal waters (50 and 60 degrees C, variable salinity) even if the latter were generally slightly faster than the former. Furthermore, similar products (HCHO, NO(2)(-), O(2)NNHCH(2)NHCHO) were obtained on alkaline hydrolysis in deionized water and abiotic degradation in coastal waters. These two findings suggested that degradation of nitramines in sterilized natural coastal waters, away from light, was mainly governed by alkaline hydrolysis. Kinetic calculations using the present parameters showed that alkaline hydrolysis of RDX and HMX in marine waters at 10 degrees C would respectively take 112 +/- 10 and 2408 +/- 217 yr to be completed (99.0%). We concluded that under natural conditions hydrolysis should not contribute significantly to the natural attenuation of HMX in coastal waters whereas it could play an active role in the natural attenuation of RDX. PMID:18453407

Monteil-Rivera, Fanny; Paquet, Louise; Giroux, Romain; Hawari, Jalal

2008-01-01

59

Progressing batch hydrolysis process  

DOEpatents

A progressive batch hydrolysis process for producing sugar from a lignocellulosic feedstock, comprising passing a stream of dilute acid serially through a plurality of percolation hydrolysis reactors charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the cellulose component of the feedstock to glucose; cooling said dilute acid stream containing glucose, after exiting the last percolation hydrolysis reactor, then feeding said dilute acid stream serially through a plurality of prehydrolysis percolation reactors, charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the hemicellulose component of said feedstock to glucose; and cooling the dilute acid stream containing glucose after it exits the last prehydrolysis reactor.

Wright, John D. (Denver, CO)

1986-01-01

60

The effect of acrylic comonomers on the hydrolytic stability of polyacrylamides at high temperature in alkaline solution  

SciTech Connect

A major cause of instability in acrylamide-based polymers used in tertiary oil recovery is hydrolysis of the amide groups, especially at alkaline pH and high temperatures. Changes in polymer composition resulting from hydrolysis can cause precipitation from sea-water solutions. This work has studied the effects of the sodium salts of acrylic acid and acrylamidomethyl propane sulfonic acid (AMPS) on the rate of hydrolysis of acrylamide copolymers in alkaline solutions at high temperatures. Copolymers were prepared containing 0 - 50% of the anionic comonomers and hydrolyzed in aqueous solution at pH 8.5 at 90/sup 0/, 107/sup 0/, and 120/sup 0/C. The extent of hydrolysis was measured by a conductimetric method, analyzing for the total carboxylate content. It was found that the rate of hydrolysis decreased as the mole ratio of either of the anionic comonomers increased and that AMPS was more effective in preventing hydrolysis at all of the temperatures studied.

Dexter, R.W.; Ryles, R.G.

1988-05-01

61

Anodes for alkaline electrolysis  

DOEpatents

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

Soloveichik, Grigorii Lev (Latham, NY)

2011-02-01

62

Alkaline igneous rocks  

SciTech Connect

In this volume, an international team of scientists provides an up-to-date overview of the nature, origin, and evolution of alkaline magmas. Particular attention is paid to carbonatites, lamprophyres, and lamproites which are rock suites of current interest not recently reviewed elsewhere. Recent work on the classical alkaline provinces of East Africa, South Greenland, and the Kola Peninsula is included together with reviews of other areas of alkaline magmatism in North and South America, East Greenland, Europe, West Africa, and the ocean basins. Other papers discuss the impact of experimental isotopic and geochemical studies of the petrogenesis of alkaline rocks. This book will be of interest to petrologists and geochemists studying alkaline igneous rocks, and to other earth scientists as a reference on the rapidly expanding field of igneous petrology.

Fitton, J.G.; Upton, B.G.J. (eds.)

1987-01-01

63

Hydrolysis of aluminum dross material to achieve zero hazardous waste.  

PubMed

A simple method with high efficiency for generating high pure hydrogen by hydrolysis in tap water of highly activated aluminum dross is established. Aluminum dross is activated by mechanically milling to particles of about 45 ?m. This leads to removal of surface layer of the aluminum particles and creation of a fresh chemically active metal surface. In contact with water the hydrolysis reaction takes place and hydrogen is released. In this process a Zero Waste concept is achieved because the other product of reaction is aluminum oxide hydroxide (AlOOH), which is nature-friendly and can be used to make high quality refractory or calcium aluminate cement. For comparison we also used pure aluminum powder and alkaline tap water solution (NaOH, KOH) at a ratio similar to that of aluminum dross content. The rates of hydrogen generated in hydrolysis reaction of pure aluminum and aluminum dross have been found to be similar. As a result of the experimental setup, a hydrogen generator was designed and assembled. Hydrogen volume generated by hydrolysis reaction was measured. The experimental results obtained reveal that aluminum dross could be economically recycled by hydrolysis process with achieving zero hazardous aluminum dross waste and hydrogen generation. PMID:22326245

David, E; Kopac, J

2012-03-30

64

HOMOGENEOUS HYDROLYSIS RATE CONSTANTS FOR SELECTED CHLORINATED METHANES, ETHANES, ETHENES, AND PROPANES  

EPA Science Inventory

Hydrolysis rate constants of 18 chlorinated methanes, ethanes, ethenes, and propanes have been measured in dilute aqueous solutions within the temperature range of 0 to 180 oC and at pH values of 3 to l4. rrhenius parapmeters were determined for both neutral and alkaline hydrolys...

65

Alkaline phosphatase activity of polymorphonuclear leucocytes and lymphocytes separated from normal human blood  

Microsoft Academic Search

Suspensions of polymorphonuclear leucocytes and lymphocytes were prepared from normal human blood by the glass bead column method of Rabinowitz (1964). The alkaline phosphatase activity of the separated cells was determined by biochemical and cytochemical techniques.Lymphocytes were found to contain an enzyme catalysing the hydrolysis of ?-glycerophosphate at alkaline pH but not of p-nitrophenylphosphate at the same pH and in

Judith K. Park

1970-01-01

66

Hydrolysis and photolysis of oxytetracycline in aqueous solution.  

PubMed

Oxytetracycline ((2Z,4S,4aR,5S,5aR,6S,12aS)-2-(amino-hydroxy-methylidene)-4-dimethylamino-5,6,10,11,12a-pentahydroxy-6-methyl-4,4a,5,5a-tetrahydrotetracene-1,3,12-trione) is a member of tetracycline antibiotics family and is widely administered to farm animals for the purpose of therapeutical treatment and health protection. Increasing attention has been paid to the environmental fate of oxytetracycline and other veterinary antibiotics with the occurrence of these antibiotics in the environment. The hydrolysis and photolysis degradation of oxytetracycline was investigated in this study. Oxytetracycline hydrolysis was found to obey the first-order model and similar rate constant values ranging from 0.094 +/- 0.001 to 0.106 +/- 0.003 day(-1) were obtained at different initial concentration ranging from 10 to 230 microM. Solution pH and temperature were shown to have remarked effects on oxytetracycline hydrolysis. The hydrolysis in pH neutral solution appeared to be much faster than in both acidic and alkaline solutions. Oxytetracycline half-life decreased from 1.2 x 10(2) to 0.15 day with the increasing temperature from 4 +/- 0.8 to 60 +/- 1 degrees C. The presence of Ca(2+) made oxytetracycline hydrolytic degradation kinetics deviate from the simple first-order model to the availability-adjusted first-order model and greatly slowed down the hydrolysis. Oxytetracycline photolysis was found to be very fast with a degradation rate constant at 3.61 +/- 0.06 day(-1), which is comparable to that of hydrolysis at 60 degrees C. The presence of Ca(2+) accelerated oxytetracycline photolysis, implying that oxytetracycline become more vulnerable to sunlight irradiation after chelating with Ca(2+). The photolysis may be the dominant degradation pathway of oxytetracycline in shallow transparent water environment. PMID:20390934

Xuan, Richeng; Arisi, Lestley; Wang, Qiquan; Yates, Scott R; Biswas, Keka C

2010-01-01

67

Destruction of waste energetic materials using base hydrolysis  

SciTech Connect

In dismantling weapons from stockpile reduction, environmentally acceptable degradation of the associated high explosive (HE) waste to non-energetic forms is a critical objective. Base hydrolysis appears to be a simple, inexpensive method for converting propellants, explosives, and pyrotechnics (PEPS) into non-energetic materials that can be released directly or, if necessary, treated further. We have demonstrated that many PEPs can be hydrolyzed with aqueous sodium hydroxide or ammonia at temperatures ranging from 60 to 150[degree]C. Hydrolysis experiments have been performed on pure compounds as well as DOE and DoD formulations, such as plastic-bonded explosive (PBX) 9404, tritonal, and rocket motor propellant. Small particle size of the energetic material is desirable, but not necessary. We have decomposed molding powder, pressed charges up to two pounds in weight, and partially exposed, metal-encased pieces. The products formed are dependent on the starting material composition, but usually consist of organic and inorganic salts, e.g., sodium formate, acetate, nitrite and nitrate. The major gaseous product from the base hydrolysis of PEPs is nitrous oxide. The time required for complete destruction varies with the material being hydrolyzed, and is dependent on solubility and mass transfer. Hydrolysis rates can be increased by particle size reduction, efficient stirring, and addition of organic solvent to the alkaline solution. Rate enhancement by ultrasonic agitation is a possibility that we have just begun to study.

Benziger, T.M.; Buntain, G.A.; Sanchez, J.A.; Spontarelli, T.

1993-01-01

68

Advances in alkaline batteries  

NASA Astrophysics Data System (ADS)

Alkaline rechargeable battery systems have been under development for more than 100 years yet. Different electrochemical couples of positive and negative materials have been subject of research and development, but only the nickel-cadmium system (NiCd) and, since about 10 years, the nickel-metal hydride system (NiMH) have achieved the stage of large volume production. Particularly, sealed NiCd and NiMH cells have been established in a variety of applications. Recent advances with the NiMH system have brought about portable batteries with energy storing capabilities coming close to those of alkaline primary cells. Although representing a technically interesting solution even for electric vehicles, relatively high cost will limit the use of rechargeable alkaline batteries to small high power batteries for hybrid electric vehicles. Basic technological developments for materials suitable for high energy and high power design are described.

Köhler, Uwe; Antonius, Christina; Bäuerlein, Peter

69

TL and ESR based identification of gamma-irradiated frozen fish using different hydrolysis techniques  

NASA Astrophysics Data System (ADS)

Frozen fish fillets (walleye Pollack and Japanese Spanish mackerel) were selected as samples for irradiation (0-10 kGy) detection trials using different hydrolysis methods. Photostimulated luminescence (PSL)-based screening analysis for gamma-irradiated frozen fillets showed low sensitivity due to limited silicate mineral contents on the samples. Same limitations were found in the thermoluminescence (TL) analysis on mineral samples isolated by density separation method. However, acid (HCl) and alkali (KOH) hydrolysis methods were effective in getting enough minerals to carry out TL analysis, which was reconfirmed through the normalization step by calculating the TL ratios (TL1/TL2). For improved electron spin resonance (ESR) analysis, alkali and enzyme (alcalase) hydrolysis methods were compared in separating minute-bone fractions. The enzymatic method provided more clear radiation-specific hydroxyapatite radicals than that of the alkaline method. Different hydrolysis methods could extend the application of TL and ESR techniques in identifying the irradiation history of frozen fish fillets.

Ahn, Jae-Jun; Akram, Kashif; Shahbaz, Hafiz Muhammad; Kwon, Joong-Ho

2014-12-01

70

Sealed alkaline battery  

Microsoft Academic Search

In an alkaline battery hermetically sealed by fusion of an insulator containing silicon oxide such as glass interposed between an annular metal cover electrically connected to one electrode of the battery and a metal member connected to the other electrode of the battery, an annular packing is disposed inside the annular metal cover and in abutment with it, and a

T. Tsuchida; K. Shinoda; N. Sakamoto

1978-01-01

71

Hydrolysis reactor for hydrogen production  

DOEpatents

In accordance with certain embodiments of the present disclosure, a method for hydrolysis of a chemical hydride is provided. The method includes adding a chemical hydride to a reaction chamber and exposing the chemical hydride in the reaction chamber to a temperature of at least about 100.degree. C. in the presence of water and in the absence of an acid or a heterogeneous catalyst, wherein the chemical hydride undergoes hydrolysis to form hydrogen gas and a byproduct material.

Davis, Thomas A.; Matthews, Michael A.

2012-12-04

72

Enzymatic fat hydrolysis and synthesis  

Microsoft Academic Search

The hydrolysis of tallow, coconut oil and olive oil, by lipase fromCandida rugosa, was studied. The reaction approximates a firstorder kinetics model. Its rate is unaffected by temperature in the range of\\u000a 26–46 C. Olive oil is more rapidly hydrolyzed compared to tallow and coconut oil. Hydrolysis is adversely affected by hydrocarbon\\u000a solvents and a nonionic surfactant. Since amounts of

Warner M. Linfield; Robert A. Barauskas; Lorraine Sivieri; Samuel Serota; Robert W. Stevenson

1984-01-01

73

Cosurfactant-Enhanced Alkaline Flooding  

Microsoft Academic Search

Many crude oil candidates for enhanced oil recovery by alkaline flooding produce their lowest interfacial tension at very low concentrations of alkali. Alkaline consumption by the rock makes propagation through the oil reservoir of such dilute alkaline solutions prohibitively slow. The dilemma of having to choose between highest displacement efficiency (lowest interfacial tension) and satisfactory displacement rate can be resolved

R. C. Nelson; J. B. Lawson; D. R. Thigpen; G. L. Stegemeier

1984-01-01

74

Net alkalinity and net acidity 1: Theoretical considerations  

USGS Publications Warehouse

Net acidity and net alkalinity are widely used, poorly defined, and commonly misunderstood parameters for the characterization of mine drainage. The authors explain theoretical expressions of 3 types of alkalinity (caustic, phenolphthalein, and total) and acidity (mineral, CO2, and total). Except for rarely-invoked negative alkalinity, theoretically defined total alkalinity is closely analogous to measured alkalinity and presents few practical interpretation problems. Theoretically defined "CO 2-acidity" is closely related to most standard titration methods with an endpoint pH of 8.3 used for determining acidity in mine drainage, but it is unfortunately named because CO2 is intentionally driven off during titration of mine-drainage samples. Using the proton condition/mass- action approach and employing graphs to illustrate speciation with changes in pH, the authors explore the concept of principal components and how to assign acidity contributions to aqueous species commonly present in mine drainage. Acidity is defined in mine drainage based on aqueous speciation at the sample pH and on the capacity of these species to undergo hydrolysis to pH 8.3. Application of this definition shows that the computed acidity in mg L -1 as CaCO3 (based on pH and analytical concentrations of dissolved FeII, FeIII, Mn, and Al in mg L -1):aciditycalculated=50{1000(10-pH)+[2(FeII)+3(FeIII)]/56+2(Mn)/ 55+3(Al)/27}underestimates contributions from HSO4- and H+, but overestimates the acidity due to Fe3+ and Al3+. However, these errors tend to approximately cancel each other. It is demonstrated that "net alkalinity" is a valid mathematical construction based on theoretical definitions of alkalinity and acidity. Further, it is shown that, for most mine-drainage solutions, a useful net alkalinity value can be derived from: (1) alkalinity and acidity values based on aqueous speciation, (2) measured alkalinity minus calculated acidity, or (3) taking the negative of the value obtained in a standard method "hot peroxide" acidity titration, provided that labs report negative values. The authors recommend the third approach; i.e., net alkalinity = -Hot Acidity. ?? 2005 Elsevier Ltd. All rights reserved.

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

2005-01-01

75

Alkaline broadening in Stars  

E-print Network

Giving new insight for line broadening theory for atoms with more structure than hydrogen in most stars. Using symbolic software to build precise wave functions corrected for ds;dp quantum defects. The profiles obtained with that approach, have peculiar trends, narrower than hydrogen, all quantum defects used are taken from atomic database topbase. Illustration of stronger effects of ions and electrons on the alkaline profiles, than neutral-neutral collision mechanism. Keywords : Stars: fundamental parameters - Atomic processes - Line: profiles.

De Kertanguy, A

2015-01-01

76

Pulp properties resulting from different pretreatments of wheat straw and their influence on enzymatic hydrolysis rate.  

PubMed

Wheat straw was subjected to three different processes prior to saccharification, namely alkaline pulping, natural pulping and autohydrolysis, in order to study their effect on the rate of enzymatic hydrolysis. Parameters like medium concentration, temperature and time have been varied in order to optimize each method. Milling the raw material to a length of 4mm beforehand showed the best cost-value-ratio compared to other grinding methods studied. Before saccharification the pulp can be stored in dried form, leading to a high yield of glucose. Furthermore the relation of pulp properties (i.e. intrinsic viscosity, Klason-lignin and hemicelluloses content, crystallinity, morphology) to cellulose hydrolysis is discussed. PMID:25058295

Rossberg, Christine; Steffien, Doreen; Bremer, Martina; Koenig, Swetlana; Carvalheiro, Florbela; Duarte, Luís C; Moniz, Patrícia; Hoernicke, Max; Bertau, Martin; Fischer, Steffen

2014-10-01

77

Enzymatic Hydrolysis of Cellulosic Biomass  

SciTech Connect

Biological conversion of cellulosic biomass to fuels and chemicals offers the high yields to products vital to economic success and the potential for very low costs. Enzymatic hydrolysis that converts lignocellulosic biomass to fermentable sugars may be the most complex step in this process due to substrate-related and enzyme-related effects and their interactions. Although enzymatic hydrolysis offers the potential for higher yields, higher selectivity, lower energy costs, and milder operating conditions than chemical processes, the mechanism of enzymatic hydrolysis and the relationship between the substrate structure and function of various glycosyl hydrolase components are not well understood. Consequently, limited success has been realized in maximizing sugar yields at very low cost. This review highlights literature on the impact of key substrate and enzyme features that influence performance to better understand fundamental strategies to advance enzymatic hydrolysis of cellulosic biomass for biological conversion to fuels and chemicals. Topics are summarized from a practical point of view including characteristics of cellulose (e.g., crystallinity, degree of polymerization, and accessible surface area) and soluble and insoluble biomass components (e.g., oligomeric xylan, lignin, etc.) released in pretreatment, and their effects on the effectiveness of enzymatic hydrolysis. We further discuss the diversity, stability, and activity of individual enzymes and their synergistic effects in deconstructing complex lignocellulosic biomass. Advanced technologies to discover and characterize novel enzymes and to improve enzyme characteristics by mutagenesis, post-translational modification, and over-expression of selected enzymes and modifications in lignocellulosic biomass are also discussed.

Yang, Bin; Dai, Ziyu; Ding, Shi-You; Wyman, Charles E.

2011-08-22

78

Evaluation of High Solids Alkaline Pretreatment of Rice Straw  

PubMed Central

Fresh-harvested, air-dried rice straw was pretreated at a water content of 5 g H2O/g straw using sodium hydroxide (NaOH) and compared to pretreatment at 10 g H2O/g straw by hydrated lime (Ca(OH)2). Full factorial experiments including parallel wash-only treatments were completed with both sources of alkali. The experiments were designed to measure the effects of alkaline loading and pretreatment time on delignification and sugar yield upon enzymatic hydrolysis. Reaction temperature was held constant at 95°C for lime pretreatment and 55°C for NaOH pretreatment. The range of delignification was 13.1% to 27.0% for lime pretreatments and was 8.6% to 23.1% for NaOH pretreatments. Both alkaline loading and reaction time had significant positive effects (p?alkaline loading had a significant positive effect on enzymatic hydrolysis. Treatment at higher temperature also improved delignification; delignification with water alone ranged from 9.9% to 14.5% for pretreatment at 95°C, but there was little effect observed at 55°C. Post-pretreatment washing of biomass was not necessary for subsequent enzymatic hydrolysis. Maximum glucose yields were 176.3 mg/g dried biomass (48.5% conversion efficiency of total glucose) in lime-pretreated and unwashed biomass and were 142.3 mg/g dried biomass (39.2% conversion efficiency of total glucose) in NaOH-pretreated and unwashed biomass. PMID:20440580

Cheng, Yu-Shen; Zheng, Yi; Yu, Chao Wei; Dooley, Todd M.; Jenkins, Bryan M.

2010-01-01

79

HYDROLYSIS OF CHLOROSTILBENE OXIDE: I. HYDROLYSIS IN HOMOGENEOUS SYSTEMS  

EPA Science Inventory

The hydrolysis kinetics of 4-chlorostilbene oxide (CSO) in buffered distilled water, in natural waters, and in sediment associated water are reported. he disappearance of CSO followed pseudo-first-order kinetics in buffered water over the experimental pH range of 3 to 11. elow pH...

80

Cellulose degradation in alkaline media upon acidic pretreatment and stabilisation.  

PubMed

The present study reports on a revised kinetic model for alkaline degradation of cellulose accounting for primary peeling/stopping reactions as well as for alkaline hydrolysis followed by secondary peeling. Oxalic acid pretreated cotton linters was utilised as the model substrate for the prehydrolysis-soda anthraquinone process. The main emphasis was investigating the effect of end-group stabilising additives such as sodium borohydride (BH), anthraquinone (AQ), and anthraquinone-2-sulphonic acid sodium salt (AQS) on the rates of the yield loss reactions. BH and AQS ensured a cellulose yield gain of 13% and 11%, respectively, compared to the reference. Both stabilisation agents decreased the content of the reducing end groups in the samples, while in the case of AQS stabilisation a 25% increase in carboxyl group content compared to the reference was also observed. As expected, the addition of end group stabilisers resulted in a significant decrease in the peeling-to-stopping rate constants ratio. PMID:24188853

Testova, Lidia; Nieminen, Kaarlo; Penttilä, Paavo A; Serimaa, Ritva; Potthast, Antje; Sixta, Herbert

2014-01-16

81

Molar enthalpy change for hydrolysis of phosphorylcreatine under conditions in muscle cells.  

PubMed Central

The enthalpy change for the hydrolysis of phosphorylcreatine (PCr) by hydrochloric acid or by alkaline phosphatase was observed at 0, 25, and 37 degrees C. The value for delta H is -44 kJ mol-1 under alkaline, Mg2+-free conditions and is almost independent of temperature, ionic strength, and concentration of reactants. In muscle the reaction is accompanied by a transfer of protons from the buffers (largely histidine) to orthophosphate, release of Mg2+ from PCr, and binding of Mg2+ to orthophosphate. Measurements are reported of the heats of these processes. The calculated value of the overall heat of hydrolysis of PCr (including these processes) at pH 7, pMg 3 is -35 kJ mol-1. PMID:3416035

Woledge, R C; Reilly, P J

1988-01-01

82

Alkaline fuel cells applications  

NASA Astrophysics Data System (ADS)

On the world-wide automobile market technical developments are increasingly determined by the dramatic restriction on emissions as well as the regimentation of fuel consumption by legislation. Therefore there is an increasing chance of a completely new technology breakthrough if it offers new opportunities, meeting the requirements of resource preservation and emission restrictions. Fuel cell technology offers the possibility to excel in today's motive power techniques in terms of environmental compatibility, consumer's profit, costs of maintenance and efficiency. The key question is economy. This will be decided by the costs of fuel cell systems if they are to be used as power generators for future electric vehicles. The alkaline hydrogen-air fuel cell system with circulating KOH electrolyte and low-cost catalysed carbon electrodes could be a promising alternative. Based on the experiences of Kordesch [K. Kordesch, Brennstoffbatterien, Springer, Wien, 1984, ISBN 3-387-81819-7; K. Kordesch, City car with H 2-air fuel cell and lead-battery, SAE Paper No. 719015, 6th IECEC, 1971], who operated a city car hybrid vehicle on public roads for 3 years in the early 1970s, improved air electrodes plus new variations of the bipolar stack assembly developed in Graz are investigated. Primary fuel choice will be a major issue until such time as cost-effective, on-board hydrogen storage is developed. Ammonia is an interesting option. The whole system, ammonia dissociator plus alkaline fuel cell (AFC), is characterised by a simple design and high efficiency.

Kordesch, Karl; Hacker, Viktor; Gsellmann, Josef; Cifrain, Martin; Faleschini, Gottfried; Enzinger, Peter; Fankhauser, Robert; Ortner, Markus; Muhr, Michael; Aronson, Robert R.

83

Economics of enzymatic hydrolysis processes  

SciTech Connect

Enzymatic hydrolysis processes have the ability to produce high yields of sugars for fermentation to fuel ethanol from lignocellulosic biomass. However, these systems have been plagued with yields, product concentrations, and reactions rates far below those that are theoretically possible. Engineering and economic analyses are presented on several fungal enzyme hydrolysis processes to illustrate the effects of the important process parameters, to quantify the progress that has been made to date, and to estimate the cost reductions that can be made through research improvements. All enzymatic hydrolysis processes require pretreatment, hydrolysis, fermentation, and enzyme production. The key effect of pretreatment is to allow access of the enzymes to the substrate. Pretreatments have been devised that make the biomass completely digestible that increase the xylose yield and concentration, and that integrate pretreatment with lignin utilization. Major improvements in enzyme activity and use of simultaneous saccharification and fermentation (SSF) have greatly reduced the inhibition of the enzymes. It now appears that ethanol inhibition of the yeast is the limiting factor. Enzyme production costs have been dramatically reduced because use of SSF has reduced enzyme loading. However, further improvements may be possible by using soluble carbon sources for production. Over the past decade, the predicted cost of ethanol from such processes has dropped from more than $4.00/gallon to approximately $1.60. Research is currently under way in the United States and has the potential to reduce the projected cost to less than $1.00/gallon. 65 refs., 16 figs., 1 tab.

Wright, J.D.

1988-02-01

84

Alkaline phosphatase activity of water column fractions and seagrass in a tropical carbonate estuary, Florida Bay  

NASA Astrophysics Data System (ADS)

Few phosphorus-depleted coastal ecosystems have been examined for their ability to hydrolyze phosphomonoesters. We examined seasonal (August 2006-April 2007) alkaline phosphatase activity in Florida Bay, a phosphorus-limited shallow estuary, using fluorescent substrate at low concentrations (?2.0 ?M). In situ dissolved inorganic and organic phosphorus levels and phosphomonoester concentrations were also determined. Water column alkaline phosphatase activity was partitioned into two particulate size fractions (>1.2 and 0.2-1.2 ?m) and freely dissolved enzymes (<0.2 ?m). Water column alkaline phosphatase activity was also compared to leaf and epiphyte activity of the dominant tropical seagrass Thalassia testudinum. Our results indicate: (1) potential alkaline phosphatase activity in Florida Bay is high compared to other marine ecosystems, resulting in rapid phosphomonoester turnover times (˜2 h). (2) Water column alkaline phosphatase activity dominates, and is split equally between particulate and dissolved fractions. (3) Alkaline phosphatase activity was highest during cyanobacterial blooms, but not when normalized to chl a. These results suggest that dissolved, heterotrophic and autotrophic alkaline phosphatase activity is stimulated by phytoplankton blooms. (4) The dissolved alkaline phosphatase activity is relatively constant, while the particulate activity is seasonally and spatially dynamic, typically associated with phytoplankton blooms. (5) Phosphomonoester concentrations throughout the bay are low, even though potential hydrolysis rates are high. We propose that bioavailable dissolved organic P is hydrolyzed by dissolved and microbial alkaline phosphatase enzymes in Florida Bay. High alkaline phosphatase activity in the bay is also promoted by long hydraulic residence times. This background activity is primarily driven by carbon and phosphorus limitation of microorganisms, and regeneration of enzymes associated with cell lysis. Pulses of inorganic phosphorus and labile organic phosphorus and nitrogen may stimulate autotrophs, particularly cyanobacteria, which in turn promote biological activity that increase alkaline phosphatase activity of both autotrophs and heterotrophs in the bay.

Koch, Marguerite S.; Kletou, Demetris C.; Tursi, Rosanna

2009-08-01

85

Kinetics of the Hydrolysis of Atmospherically Relevant  

E-print Network

Kinetics of the Hydrolysis of Atmospherically Relevant Isoprene-Derived Hydroxy Epoxides N E I L C and that these epoxides are likely to undergo efficient acid- catalyzed hydrolysis on SOA to 2-methyl-1, the specifichydroxyepoxidesobservedintheisoprenephotooxidation experiment (as well as several other related species) were synthesized, and the hydrolysis

Elrod, Matthew J.

86

Chick embryo anchored alkaline phosphatase and mineralization process in vitro.  

PubMed

Bone alkaline phosphatase with glycolipid anchor (GPI-bALP) from chick embryo femurs in a medium without exogenous inorganic phosphate, but containing calcium and GPI-bALP substrates, served as in vitro model of mineral formation. The mineralization process was initiated by the formation of inorganic phosphate, arising from the hydrolysis of a substrate by GPI-bALP. Several mineralization media containing different substrates were analysed after an incubation time ranging from 1.5 h to 144 h. The measurements of Ca/Pi ratio and infrared spectra permitted us to follow the presence of amorphous and noncrystalline structures, while the analysis of X-ray diffraction data allowed us to obtain the stoichiometry of crystals. The hydrolysis of phosphocreatine, glucose 1-phosphate, glucose 6-phosphate, glucose 1,6-bisphosphate by GPI-bALP produced hydroxyapatite in a manner similar to that of beta-glycerophosphate. Several distinct steps in the mineral formation were observed. Amorphous calcium phosphate was present at the onset of the mineral formation, then poorly formed hydroxyapatite crystalline structures were observed, followed by the presence of hydroxyapatite crystals after 6-12 h incubation time. However, the hydrolysis of either ATP or ADP, catalysed by GPI-bALP in calcium-containing medium, did not lead to the formation of any hydroxyapatite crystals, even after 144 h incubation time, when hydrolysis of both nucleotides was completed. In contrast, the hydrolysis of AMP by GPI-bALP led to the appearance of hydroxyapatite crystals after 12 h incubation time. The hydroxyapatite formation depends not only on the ability of GPI-bALP to hydrolyze the organic phosphate but also on the nature of substrates affecting the nucleation process or producing inhibitors of the mineralization. PMID:12709068

Hamade, Eva; Azzar, Gérard; Radisson, Jacqueline; Buchet, René; Roux, Bernard

2003-05-01

87

Probing the Origin of the Compromised Catalysis of E. coli Alkaline Phosphatase in its Promiscuous Sulfatase Reaction  

E-print Network

that is maintained via selective pressure.11-17 Catalytic promis- cuity is thought to provide an important foothold-mail: herschla@stanford.edu; hengge@cc.usu.edu Abstract: The catalytic promiscuity of E. coli alkaline of the 109 -fold greater catalytic proficiency by AP for phosphate monoester hydrolysis relative to sulfate

Herschlag, Dan

88

Alkaline hydrothermal conversion of cellulose to bio-oil: Influence of alkalinity on reaction pathway change  

Microsoft Academic Search

The effects of alkalinity on alkaline hydrothermal conversion (alkaline-HTC) of cellulose to bio-oil were investigated in this study. The results showed that the initial alkalinity greatly influenced the reaction pathways. Under initial strong alkaline conditions with final pH greater than 7, alkaline-HTC only followed the alkaline pathway. However, under initial weak alkaline conditions with final pH of less than 7,

Sudong Yin; Anil K. Mehrotra; Zhongchao Tan

2011-01-01

89

Characteristics and enzymatic hydrolysis of cellulose-rich fractions from steam exploded and sequentially alkali delignified bamboo (Phyllostachys pubescens).  

PubMed

In this study, cellulose-rich fractions from bamboo were prepared with steam explosion pretreatment (SEP) followed by a successive alkaline delignification to improve the enzymatic digestibility for an efficient bioethanol production. The cellulose-rich fractions obtained were characterized by FT-IR, XRD, CP/MAS (13)C NMR, SEM, and BET surface area. It was found that the SEP alone significantly removed partial hemicelluloses, while the synergistic treatment by SEP and alkaline delignification removed most hemicelluloses and lignin. Results from enzymatic hydrolysis showed that SEP alone improved the enzymatic hydrolysis rate by 7.9-33.1%, while the synergistic treatment by SEP and alkaline delignification enhanced the rate by 45.7-63.9%. The synergistic treatment by SEP at 2.0 MPa for 5 min with water impregnation followed by a successive alkaline delignification with 0.5% NaOH and 70% ethanol containing 1.5% NaOH resulted in a maximum enzymatic hydrolysis rate of 70.6%. PMID:24830378

Sun, Shao-Ni; Cao, Xue-Fei; Zhang, Xue-Ming; Xu, Feng; Sun, Run-Cang; Jones, Gwynn Lloyd

2014-07-01

90

Smart nanoprobes for the detection of alkaline phosphatase activity during osteoblast differentiation.  

PubMed

Gold nanoparticle-conjugated fluorescent hydroxyapatite (AuFHAp) was developed as a smart nanoprobe for measuring alkaline phosphatase (ALP) activity. AuFHAp showed NIR fluorescence due to the hydrolysis of its phosphate groups by ALP. In addition, gold nanoparticles help reduce the nonspecific signal by absorbing nonspecific fluorescence. Through in vitro tests, we confirmed that the AuFHAp probe was capable of detecting ALP levels related to osteoblast activity in living cells with high fluorescence intensity. PMID:25623488

Lim, Eun-Kyung; Keem, Joo Oak; Yun, Hui-Suk; Jung, Jinyoung; Chung, Bong Hyun

2015-02-01

91

Understanding of alkaline pretreatment parameters for corn stover enzymatic saccharification  

PubMed Central

Background Previous research on alkaline pretreatment has mainly focused on optimization of the process parameters to improve substrate digestibility. To achieve satisfactory sugar yield, extremely high chemical loading and enzyme dosages were typically used. Relatively little attention has been paid to reduction of chemical consumption and process waste management, which has proven to be an indispensable component of the bio-refineries. To indicate alkali strength, both alkali concentration in pretreatment solution (g alkali/g pretreatment liquor or g alkali/L pretreatment liquor) and alkali loading based on biomass solids (g alkali/g dry biomass) have been widely used. The dual approaches make it difficult to compare the chemical consumption in different process scenarios while evaluating the cost effectiveness of this pretreatment technology. The current work addresses these issues through pretreatment of corn stover at various combinations of pretreatment conditions. Enzymatic hydrolysis with different enzyme blends was subsequently performed to identify the effects of pretreatment parameters on substrate digestibility as well as process operational and capital costs. Results The results showed that sodium hydroxide loading is the most dominant variable for enzymatic digestibility. To reach 70% glucan conversion while avoiding extensive degradation of hemicellulose, approximately 0.08 g NaOH/g corn stover was required. It was also concluded that alkali loading based on total solids (g NaOH/g dry biomass) governs the pretreatment efficiency. Supplementing cellulase with accessory enzymes such as ?-arabinofuranosidase and ?-xylosidase significantly improved the conversion of the hemicellulose by 6–17%. Conclusions The current work presents the impact of alkaline pretreatment parameters on the enzymatic hydrolysis of corn stover as well as the process operational and capital investment costs. The high chemical consumption for alkaline pretreatment technology indicates that the main challenge for commercialization is chemical recovery. However, repurposing or co-locating a biorefinery with a paper mill would be advantageous from an economic point of view. PMID:23356733

2013-01-01

92

HYDROLYSIS  

EPA Science Inventory

Hydrolytic processes provide the baseline loss rate for any chemical in an aqueous envi- ronment. Although various hydrolytic pathways account for significant degradation of certain classes of organic chemicals, other organic structures are completely inert. Strictly speaking, hy...

93

Alkalinity tolerance of peach rootstocks  

E-print Network

ALKALINITY TOLERANCE OF PEACH ROOTSTOCKS A Thesis by YAN SHI Submitted to the Office of Graduate Studies of Texas A8 M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1992 Major Subject...: Horticulture ALKALINITY TOLERANCE OF PEACH ROOTSTOCKS A Thesis by YAN SHI Approved as to style and content by: David H. Byrne (Chair of committee) Richard H. Loeppert (Member) David Wm. Reed (Member) R. Daniel lineberger (Head of Department) May...

Shi, Yan

2012-06-07

94

Hydrolysis of diadenosine polyphosphates by nucleotide pyrophosphatases/phosphodiesterases.  

PubMed

Diadenosine polyphosphates (ApnAs) act as extracellular signaling molecules in a broad variety of tissues. They were shown to be hydrolyzed by surface-located enzymes in an asymmetric manner, generating AMP and Apn-1 from ApnA. The molecular identity of the enzymes responsible remains unclear. We analyzed the potential of NPP1, NPP2, and NPP3, the three members of the ecto-nucleotide pyrophosphatase/phosphodiesterase family, to hydrolyze the diadenosine polyphosphates diadenosine 5',5"'-P1,P3-triphosphate (Ap3A), diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A), and diadenosine 5',5"'-P1,P5-pentaphosphate, (Ap5A), and the diguanosine polyphosphate, diguanosine 5',5"'-P1,P4-tetraphosphate (Gp4G). Each of the three enzymes hydrolyzed Ap3A, Ap4A, and Ap5A at comparable rates. Gp4G was hydrolyzed by NPP1 and NPP2 at rates similar to Ap4A, but only at half this rate by NPP3. Hydrolysis was asymmetric, involving the alpha,beta-pyrophosphate bond. ApnA hydrolysis had a very alkaline pH optimum and was inhibited by EDTA. Michaelis constant (Km) values for Ap3A were 5.1 micro m, 8.0 micro m, and 49.5 micro m for NPP1, NPP2, and NPP3, respectively. Our results suggest that NPP1, NPP2, and NPP3 are major enzyme candidates for the hydrolysis of extracellular diadenosine polyphosphates in vertebrate tissues. PMID:12846830

Vollmayer, Petra; Clair, Timothy; Goding, James W; Sano, Kimihiko; Servos, Jörg; Zimmermann, Herbert

2003-07-01

95

Acid Hydrolysis of Trioxalatocobaltate (III) Ion  

ERIC Educational Resources Information Center

Describes an investigation involving acid hydrolysis and using both volumetric and kinetic techniques. Presents examples of the determination of the rate constant and its variation with temperature. (GS)

Wiggans, P. W.

1975-01-01

96

ORGANOPHOSPHATE AND ORGANOPHOSPHOROTHIONATE ESTERS: APPLICATION OF LINEAR FREE ENERGY RELATIONSHIPS TO ESTIMATE HYDROLYSIS RATE CONSTANTS FOR USE IN ENVIRONMENTAL FATE ASSESSMENT  

EPA Science Inventory

Hydrolysis rate constants required for assessing the environmental fate of certain organophosphate and organophosphorothionate esters may be estimated by use of linear free energy relationships (LFERs). LFERs for the second-order alkaline rate constants and the pKa of the conjuga...

97

Effect of thermal hydrolysis pre-treatment on anaerobic digestion of municipal biowaste: a pilot scale study in China.  

PubMed

Co-digestion of wasted sewage sludge, restaurant kitchen waste, and fruit-vegetable waste was carried out in a pilot plant with thermal hydrolysis pre-treatment. Steam was used as heat source for thermal hydrolysis. It was found 38.3% of volatile suspended solids were dissolved after thermal hydrolysis, with digestibility increased by 115%. These results were more significant than those from lab studies using electricity as heat source due to more uniform heating. Anaerobic digesters were then operated under organic loading rates of about 1.5 and 3 kg VS/(m³ d). Little difference was found for digesters with and without thermal pre-treatment in biogas production and volatile solids removal. However, when looking into the digestion process, it was found digestion rate was almost doubled after thermal hydrolysis. Digester was also more stable with thermal hydrolysis pre-treatment. Less volatile fatty acids (VFAs) were accumulated and the VFAs/alkalinity ratio was also lower. Batch experiments showed the lag phase can be eliminated by thermal pre-treatment, implying the advantage could be more significant under a shorter hydraulic retention time. Moreover, it was estimated energy cost for thermal hydrolysis can be partly balanced by decreasing viscosity and improving dewaterability of the digestate. PMID:23419457

Zhou, Yingjun; Takaoka, Masaki; Wang, Wei; Liu, Xiao; Oshita, Kazuyuki

2013-07-01

98

Microwave Pretreatment For Hydrolysis Of Cellulose  

NASA Technical Reports Server (NTRS)

Microwave pretreatment enhances enzymatic hydrolysis of cellulosic wastes into soluble saccharides used as feedstocks for foods, fuels, and other products. Low consumption of energy, high yield, and low risk of proposed hydrolysis process incorporating microwave pretreatment makes process viable alternative to composting.

Cullingford, Hatice S.; George, Clifford E.; Lightsey, George R.

1993-01-01

99

Rate of Hydrolysis of Tertiary Halogeno Alkanes  

ERIC Educational Resources Information Center

Describes an experiment to measure the relative rate of hydrolysis of the 2-x-2 methylpropanes, where x is bromo, chloro or iodo. The results are plotted on a graph from which the relative rate of hydrolysis can be deduced. (Author/GA)

Pritchard, D. R.

1978-01-01

100

Alkaline phytase from lily pollen: Investigation of biochemical properties.  

PubMed

Phytases catalyze the hydrolysis of phytic acid (InsP6, myo-inositol hexakisphosphate), the most abundant inositol phosphate in cells. In cereal grains and legumes, it constitutes 3-5% of the dry weight of seeds. The inability of humans and monogastric animals such as swine and poultry to absorb complexed InsP6 has led to nutritional and environmental problems. The efficacy of supplemental phytases to address these issues is well established; thus, there is a need for phytases with a range of biochemical and biophysical properties for numerous applications. An alkaline phytase that shows unique catalytic properties was isolated from plant tissues. In this paper, we report on the biochemical properties of an alkaline phytase from pollen grains of Lilium longiflorum. The enzyme exhibits narrow substrate specificity, it hydrolyzed InsP6 and para-nitrophenyl phosphate (pNPP). Alkaline phytase followed Michaelis-Menten kinetics with a K(m) of 81 microM and V(max) of 217 nmol Pi/min/mg with InsP6 and a K(m) of 372 microM and V(max) of 1272 nmol Pi/min/mg with pNPP. The pH optimum was 8.0 with InsP6 as the substrate and 7.0 with pNPP. Alkaline phytase was activated by calcium and inactivated by ethylenediaminetetraacetic acid; however, the enzyme retained a low level of activity even in Ca2+-free medium. Fluoride as well as myo-inositol hexasulfate did not have any inhibitory affect, whereas vanadate inhibited the enzyme. The enzyme was activated by sodium chloride and potassium chloride and inactivated by magnesium chloride; the activation by salts followed the Hofmeister series. The temperature optimum for hydrolysis is 55 degrees C; the enzyme was stable at 55 degrees C for about 30 min. The enzyme has unique properties that suggest the potential to be useful as a feed supplement. PMID:16051182

Jog, Sonali P; Garchow, Barry G; Mehta, Bakul Dhagat; Murthy, Pushpalatha P N

2005-08-15

101

Edinburgh Research Explorer Organotrifluoroborate Hydrolysis: Boronic Acid Release  

E-print Network

Edinburgh Research Explorer Organotrifluoroborate Hydrolysis: Boronic Acid Release Mechanism, 'Organotrifluoroborate Hydrolysis: Boronic Acid Release Mechanism and an Acid­Base Paradox in Cross-Coupling' Journal immediately and investigate your claim. Download date: 16. Sep. 2014 #12;Organotrifluoroborate Hydrolysis

Millar, Andrew J.

102

Subcellular localization of marine bacterial alkaline phosphatases.  

PubMed

Bacterial alkaline phosphatases (APases) are important enzymes in organophosphate utilization in the ocean. The subcellular localization of APases has significant ecological implications for marine biota but is largely unknown. The extensive metagenomic sequence databases from the Global Ocean Sampling Expedition provide an opportunity to address this question. A bioinformatics pipeline was developed to identify marine bacterial APases from the metagenomic databases, and a consensus classification algorithm was designed to predict their subcellular localizations. We identified 3,733 bacterial APase sequences (including PhoA, PhoD, and PhoX) and found that cytoplasmic (41%) and extracellular (30%) APases exceed their periplasmic (17%), outer membrane (12%), and inner membrane (0.9%) counterparts. The unexpectedly high abundance of cytoplasmic APases suggests that the transport and intracellular hydrolysis of small organophosphate molecules is an important mechanism for bacterial acquisition of phosphorus (P) in the surface ocean. On average, each marine bacterium possessed at least one suite of uptake of glycerol phosphate (ugp) genes (e.g., ugpA, ugpB, ugpC, ugpE) for dissolved organic phosphorus (DOP) transport, but only half of them had ugpQ, which hydrolyzes transported DOP, indicating that cytoplasmic APases play a role in hydrolyzing transported DOP. The most abundant heterotrophic marine bacteria, alpha- and gamma-Proteobacteria, might hydrolyze DOP outside the cytoplasmic membrane, but the former could also transport and hydrolyze DOP in the cytoplasm. The abundant extracellular APases could provide bioavailable P for organisms that cannot directly access organophosphates, and thereby increase marine biological productivity and diversity. PMID:19926862

Luo, Haiwei; Benner, Ronald; Long, Richard A; Hu, Jianjun

2009-12-15

103

Detection of sarin hydrolysis products from sarin-like organophosphorus agent-exposed human erythrocytes.  

PubMed

A sarin-like organophosphorus agent, [bis(isopropyl methyl)phosphonate; BIMP], was synthesized. This agent has the same phosphonate group as sarin and also has the same anti-acetylcholinesterase activity potency as sarin. The ID50 and LD50 values of BIMP in mice after intravenous injection were 3.9 nM and 0.8 mg/kg, respectively. The AChE activities of their red blood cells and brains were dose-dependently reduced by intravenous BIMP. After preparation of experimental BIMP-exposed human red blood cells, BIMP-bound acetylcholinesterase (AChE) was solubilized from erythrocyte membranes, purified by immunoaffinity chromatography, digested with trypsin, and the sarin hydrolysis products bound to AChE were released by alkaline phosphatase digestion. The digested sarin hydrolysis products were subjected to trimethylsilyl (TMS) derivatization and detected by gas chromatography-mass spectrometry. Isopropyl methylphosphonic- and methylphosphonic acids, which are the sarin hydrolysis products, were detected in experimental BIMP-exposed human red blood cells. This new method, which enables sarin's hydrolysis products to be detected in BIMP-exposed erythrocytes, is a useful tool for studying sarin-poisoning victims. PMID:9389333

Nagao, M; Takatori, T; Matsuda, Y; Nakajima, M; Niijima, H; Iwase, H; Iwadate, K; Amano, T

1997-11-01

104

The improvement of enzymatic hydrolysis efficiency of rape straw and Miscanthus giganteus polysaccharides.  

PubMed

The research was carried out with the aim to determine the impact of various combinations of cellulase and hemicellulase preparations on the effectiveness of enzymatic hydrolysis of polysaccharides of rape straw and Miscanthus giganteus after alkaline pretreatment. Their effectiveness was evaluated based on the quantity of saccharides released during enzymatic reaction and yield calculated in respect of the sum of polysaccharides present in native substrates. The complex of preparations produced from Trichoderma longibrachiatum fungi turned out to be the most effective. The study demonstrated a significant effect of xylanases from T. longibrachiatum, the presence of which evoked a 27-45% increase in the effectiveness of polysaccharides hydrolysis compared to the enzymatic complexes without their addition. In addition, results achieved in this study confirmed the necessity of applying the pretreatment in lignocellulose substrates conversion into bioethanol. PMID:24269826

Swi?tek, Karolina; Lewandowska, Ma?gorzata; Swi?tek, Magdalena; Bednarski, W?odzimierz; Brzozowski, Bartosz

2014-01-01

105

TLC determination of meloxicam in tablets and after acidic and alkaline hydrolysis.  

PubMed

A simple and rapid method for separation and determination of meloxicam and its degradation products by thin-layer chromatography with densitometric detection in pharmaceutical preparations was described. The method employed TLC F254 plates as the stationary phase. The solvent system consisted of ethyl acetate : toluene : butylamine (2:2:1, v/v/v). Densitometric analysis was carried out in absorbance mode at wavelength of 297 nm. The method was validated for linearity, precision and accuracy. The limits of detection and determination were 0.96 ?g per spot and 2.90 ?g per spot, respectively. The drug was degraded in acidic and basic environment, at different temperatures. The degradation products were well resolved from the active substance. The HPLC-MS/MS method for the identification of degradation products of meloxicam (i.e. 5-methylthiazol- 2-ylamine and 5-(dioxide-l(6)-sulfanylidene)-6-methylidenecyclohexa-1,3-diene) was investigated. Because the presented method allows the efficient separation of the drug from some of its degradation products, so it can be used as a stability-indicating analysis. PMID:22568036

Starek, Ma?gorzata; Krzek, Jan

2012-01-01

106

Cardiotoxicity of commercial 5-fluorouracil vials stems from the alkaline hydrolysis of this drug.  

PubMed Central

The cardiotoxicity of 5-fluorouracil (FU) was attributed to impurities present in the injected vials. One of these impurities was identified as fluoroacetaldehyde which is metabolised by isolated perfused rabbit hearts into fluoroacetate (FAC), a highly cardiotoxic compound. FAC was also detected in the urine of patients treated with FU. These impurities were found to be degradation products of FU that are formed in the basic medium employed to dissolve this compound. To avoid chemical degradation of this antineoplastic drug, the solution of FU that will be injected should be prepared immediately before use. PMID:1637660

Lemaire, L.; Malet-Martino, M. C.; de Forni, M.; Martino, R.; Lasserre, B.

1992-01-01

107

Alkaline twin-screw extrusion pretreatment for fermentable sugar production  

PubMed Central

Background The inevitable depletion of fossil fuels has resulted in an increasing worldwide interest in exploring alternative and sustainable energy sources. Lignocellulose, which is the most abundant biomass on earth, is widely regarded as a promising raw material to produce fuel ethanol. Pretreatment is an essential step to disrupt the recalcitrance of lignocellulosic matrix for enzymatic saccharification and bioethanol production. This paper established an ATSE (alkaline twin-screw extrusion pretreatment) process using a specially designed twin-screw extruder in the presence of alkaline solution to improve the enzymatic hydrolysis efficiency of corn stover for the production of fermentable sugars. Results The ATSE pretreatment was conducted with a biomass/liquid ratio of 1/2 (w/w) at a temperature of 99°C without heating equipment. The results indicated that ATSE pretreatment is effective in improving the enzymatic digestibility of corn stover. Sodium hydroxide loading is more influential factor affecting both sugar yield and lignin degradation than heat preservation time. After ATSE pretreatment under the proper conditions (NaOH loading of 0.06 g/g biomass during ATSE and 1 hour heat preservation after extrusion), 71% lignin removal was achieved and the conversions of glucan and xylan in the pretreated biomass can reach to 83% and 89% respectively via subsequent enzymatic hydrolysis (cellulase loading of 20 FPU/g-biomass and substrate consistency of 2%). About 78% of the original polysaccharides were converted into fermentable sugars. Conclusions With the physicochemical functions in extrusion, the ATSE method can effectively overcome the recalcitrance of lignocellulose for the production of fermentable sugars from corn stover. This process can be considered as a promising pretreatment method due to its relatively low temperature (99°C), high biomass/liquid ratio (1/2) and satisfied total sugar yield (78%), despite further study is needed for process optimization and cost reduction. PMID:23834726

2013-01-01

108

Testing alkalinity in water systems (simulation)  

NSDL National Science Digital Library

This investigation is a laboratory activity in which the alkalinity of 2 types of substrates (carbonate vs. non-carbonate) are compared on the basis of titration. Students will reflect on the relationship of alkalinity and toxic heavy metals.

Juliet Peterson DeLaSalle High School, Minneapolis, MN Teaching ideas from: Project Wet, Water Education for Teachers as found in: "Healthy Water Healthy People, Field Monitoring Guide "(2003)

109

Nucleotide sequences encoding a thermostable alkaline protease  

DOEpatents

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

Wilson, David B. (Ithaca, NY); Lao, Guifang (Bethesda, MD)

1998-01-01

110

Nucleotide sequences encoding a thermostable alkaline protease  

DOEpatents

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

Wilson, D.B.; Lao, G.

1998-01-06

111

Lightweight electroconductive solderless internal cell connector for alkaline or alkaline earth metal batteries  

SciTech Connect

This patent describes a combination with an alkaline metal or alkaline earth metal battery a lightweight solderless connector for internal battery electrical connection. It comprises a core of alkaline metal or alkaline earth metal, an outer electrically insulating covering on the core, the outer covering having an adhesive coating thereon in contact with the core.

Hope, H.F.; Hope, S.F.

1991-10-01

112

Membrane-bound alkaline phosphatase from ectopic mineralization and rat bone marrow cell culture.  

PubMed

Cells from rat bone marrow exhibit the proliferation-differentiation sequence of osteoblasts, form mineralized extracellular matrix in vitro and release alkaline phosphatase into the medium. Membrane-bound alkaline phosphatase was obtained by method that is easy to reproduce, simpler and fast when compared with the method used to obtain the enzyme from rat osseous plate. The membrane-bound alkaline phosphatase from cultures of rat bone marrow cells has a MW(r) of about 120 kDa and specific PNPP activity of 1200 U/mg. The ecto-enzyme is anchored to the plasma membrane by the GPI anchor and can be released by PIPLC (selective treatment) or polidocanol (0.2 mg/mL protein and 1% (w/v) detergent). The apparent optimum pH for PNPP hydrolysis by the enzyme was pH 10. This fraction hydrolyzes ATP (240 U/mg), ADP (350 U/mg), glucose 1-phosphate (1100 U/mg), glucose 6-phosphate (340 U/mg), fructose 6-phosphate (460 U/mg), pyrophosphate (330 U/mg) and beta-glycerophosphate (600 U/mg). Cooperative effects were observed for the hydrolysis of PPi and beta-glycerophosphate. PNPPase activity was inhibited by 0.1 mM vanadate (46%), 0.1 mM ZnCl2 (68%), 1 mM levamisole (66%), 1 mM arsenate (44%), 10 mM phosphate (21%) and 1 mM theophylline (72%). We report the biochemical characterization of membrane-bound alkaline phosphatase obtained from rat bone marrow cells cultures, using a method that is simple, rapid and easy to reproduce. Its properties are compared with those of rat osseous plate enzyme and revealed that the alkaline phosphatase obtained has some kinetics and structural behaviors with higher levels of enzymatic activity, facilitating the comprehension of the mineralization process and its function. PMID:16798036

Simão, Ana Maria S; Beloti, Márcio M; Cezarino, Rodrigo M; Rosa, Adalberto Luiz; Pizauro, João M; Ciancaglini, Pietro

2007-04-01

113

Enzymatic hydrolysis of cellulose: theory and applications  

SciTech Connect

A large amount of research has been published on the theory of enzymatic hydrolysis and the various microbial, and other, sources of the enzymes. The present report endeavors to supplement this information by emphasizing insofar as possible the status of the technology and of potential industrial processes for production of sugars from cellulose. A substantial research effort on cellulose conversion has been underway in the authors' laboratories at the University of California at Berkeley over the past ten years. This report is based in part upon this background of experience, and experimental data from relatively recent studies are presented in certain sections to make the information as timely and useful as possible. Because of current interest in production of ethanol a section is included which summarizes various methods for high productivity fermentation systems. Chapter titles are: Theory of enzymatic hydrolysis; production of cellulase and xylanase; hydrolysis of agricultural residues, enzymatic hydrolysis processes, high productivity ethanol fermentation; and ethanol economics. (DMC)

Wilke, C.R.; Maiorella, B.; Sciamanna, A.; Tangnu, K.; Wiley, D.; Wong, H.

1980-06-01

114

Effect of surfactants on cellulose hydrolysis  

SciTech Connect

The effect of surfactants on the heterogeneous enzymatic hydrolysis of Sigmacell 100 cellulose and of steam-exploded wood was studied. Certain biosurfactants (sophorolipid, rhamnolipid, bacitracin) and Tween 80 increased the rate of hydrolysis of Sigmacell 100, as measured by the amount of reducing sugar produced, by as much as seven times. The hydrolysis of steam-exploded wood was increased by 67% in the presence of sophorolipid. At the same time, sophorolipid was found to decrease the amount of enzyme absorbed onto the cellulose at equilibrium. Sophorolipid had the greatest effect on cellulose hydrolysis when it was present from the beginning of the experiment and when the enzyme/cellulose ratio was low.

Helle, S.S.; Duff, S.J.B. (Univ. of British Columbia, Vancouver, British Columbia (Canada). Pulp and Paper Centre and Dept. of Chemical Engineering); Cooper, D.G. (McGill Univ., Montreal, Quebec (Canada). Chemical Engineering Dept.)

1993-08-20

115

Optimization of alkaline pretreatment of coffee pulp for production of bioethanol.  

PubMed

The use of lignocellulosic raw materials in bioethanol production has been intensively investigated in recent years. However, for efficient conversion to ethanol, many pretreatment steps are required prior to hydrolysis and fermentation. Coffee stands out as the most important agricultural product in Brazil and wastes such as pulp and coffee husk are generated during the wet and dry processing to obtain green grains, respectively. This work focused on the optimization of alkaline pretreatment of coffee pulp with the aim of making its use in the alcoholic fermentation. A central composite rotatable design was used with three independent variables: sodium hydroxide and calcium hydroxide concentrations and alkaline pretreatment time, totaling 17 experiments. After alkaline pretreatment the concentration of cellulose, hemicellulose, and lignin remaining in the material, the subsequent hydrolysis of the cellulose component and its fermentation of substrate were evaluated. The results indicated that pretreatment using 4% (w/v) sodium hydroxide solution, with no calcium hydroxide, and 25 min treatment time gave the best results (69.18% cellulose remaining, 44.15% hemicelluloses remaining, 25.19% lignin remaining, 38.13 g/L of reducing sugars, and 27.02 g/L of glucose) and produced 13.66 g/L of ethanol with a yield of 0.4 g ethanol/g glucose. PMID:24376222

Menezes, Evandro G T; do Carmo, Juliana R; Alves, José Guilherme L F; Menezes, Aline G T; Guimarães, Isabela C; Queiroz, Fabiana; Pimenta, Carlos J

2014-01-01

116

Random Hydrolysis Controls the Dynamic Instability of Microtubules Ranjith Padinhateeri,  

E-print Network

Random Hydrolysis Controls the Dynamic Instability of Microtubules Ranjith Padinhateeri, * Anatoly hydrolysis. Despite decades of experimental work in this field, the precise mechanism of hydrolysis to the vectorial model, hydrolysis occurs only at the unique interface between units bound to GTP/ATP and units

Lacoste, David

117

Review: Enzymatic Hydrolysis of Cellulosic Biomass  

SciTech Connect

Biological conversion of cellulosic biomass to fuels and chemicals offers the high yields to products vital to economic success and the potential for very low costs. Enzymatic hydrolysis that converts lignocellulosic biomass to fermentable sugars may be the most complex step in this process due to substrate-related and enzyme-related effects and their interactions. Although enzymatic hydrolysis offers the potential for higher yields, higher selectivity, lower energy costs, and milder operating conditions than chemical processes, the mechanism of enzymatic hydrolysis and the relationship between the substrate structure and function of various glycosyl hydrolase components are not well understood. Consequently, limited success has been realized in maximizing sugar yields at very low cost. This review highlights literature on the impact of key substrate and enzyme features that influence performance to better understand fundamental strategies to advance enzymatic hydrolysis of cellulosic biomass for biological conversion to fuels and chemicals. Topics are summarized from a practical point of view including characteristics of cellulose (e.g., crystallinity, degree of polymerization, and accessible surface area) and soluble and insoluble biomass components (e.g., oligomeric xylan, lignin, etc.) released in pretreatment, and their effects on the effectiveness of enzymatic hydrolysis. We further discuss the diversity, stability, and activity of individual enzymes and their synergistic effects in deconstructing complex lignocellulosic biomass. Advanced technologies to discover and characterize novel enzymes and to improve enzyme characteristics by mutagenesis, post-translational modification, and over-expression of selected enzymes and modifications in lignocellulosic biomass are also discussed.

Yang, Bin; Dai, Ziyu; Ding, Shi-You; Wyman, Charles E.

2011-07-16

118

Catalytic Activity of Human Placental Alkaline Phosphatase (PLAP): Insights from a Computational Study.  

PubMed

Alkaline phosphatases (APs) catalyze the hydrolysis and transphosphorylation of phosphate monoesters. Quantum-mechanical computational methods were employed to study the catalytic mechanism of human placental AP (PLAP). An active-site model was used, constructed on the basis of the X-ray crystal structure of the enzyme. Kinetic and thermodynamic evaluations were achieved for each reaction step. Calculations shed light on the mechanistic differences that had been experimentally observed between aryl and alkyl phosphates, particularly regarding the rate-determining step. The functional implications of relevant residues in the active site were examined. The present theoretical study rationalizes experimental observations previously reported in the literature. PMID:25409280

Borosky, Gabriela L

2014-12-11

119

Production of alkaline protease by Pseudomonas aeruginosa using proteinaceous solid waste generated from leather manufacturing industries.  

PubMed

Animal fleshing (ANFL), the major proteinaceous solid waste discharged from leather manufacturing industries was used as the substrate for the production of alkaline protease by Pseudomonas aeruginosa. The strain isolated from the tannery wastewater was selected for its ability to produce protease of activity in the range 1160-1175 U ml(-1). The selective removal of non-fibrillar proteins such as albumin and globulin from ANFL by the protease enzyme during the progress of hydrolysis was confirmed using scanning electron microscopy (SEM). The breakdown of ANFL was also confirmed from the amino acid release into the fermentation medium by P. aeruginosa using high performance liquid chromatography (HPLC). PMID:17481889

Ganesh Kumar, A; Swarnalatha, S; Sairam, B; Sekaran, G

2008-04-01

120

Developments in Alkaline Tin Electrorefining  

NASA Astrophysics Data System (ADS)

Although alkaline stannate baths for electrorefining of tin have been used for some time, there is still room for improvement The effects of alkali concentration, current density and temperature on the cathodic current efficiency have been studied, and a bath temperature of 75°C is recommended. To avoid unstable conditions in the bath, a special treatment to the anode and application of an auxiliary cathode are necessary. Many of the metallic impurities present in the crude tin anode go into the slimes in the form of hydroxides, but lead impurities can only be tolerated if concentrations are less than one percent.

Saba, A. E.; Afifi, S. E.; El Sherief, A. E.

1988-08-01

121

Migration and hydrolysis of hydrophobic polylactide plasticizer.  

PubMed

Hydrophobic plasticizer protects polylactide (PLA) against hydrolytic degradation but still migrates to aging medium and there undergoes further hydrolysis contributing to the spectrum of degradation products. PLA plasticized with hydrophobic acetyl tributyl citrate (ATC) plasticizer showed a slower degradation rate compared with pure PLA because of the increased hydrophobicity of the material. The enhanced bulk hydrophobicity also overcame the degradation enhancing effect of hydrophilic surface grafting. In addition to plasticization with ATC, some of the samples were also surface grafted with acrylic acid. The materials were subjected to hydrolysis at 37 and 60 degrees C for up to 364 days to compare the effect of hydrophobic and hydrophilic bulk and surface modifications. Although considered insoluble in water, the plasticizer was detected in the water solutions immediately upon immersion of the materials, and the relative abundance of the ATC degradation products increased with hydrolysis time. PMID:19928814

Höglund, Anders; Hakkarainen, Minna; Albertsson, Ann-Christine

2010-01-11

122

A Novel Alkaline ?-Galactosidase from Melon Fruit with a Substrate Preference for Raffinose1  

PubMed Central

The cucurbits translocate the galactosyl-sucrose oligosaccharides raffinose and stachyose, therefore, ?-galactosidase (?-d-galactoside galactohydrolase, EC 3.2.1.22) is expected to function as the initial enzyme of photoassimilate catabolism. However, the previously described alkaline ?-galactosidase is specific for the tetrasaccharide stachyose, leaving raffinose catabolism in these tissues as an enigma. In this paper we report the partial purification and characterization of three ?-galactosidases, including a novel alkaline ?-galactosidase (form I) from melon (Cucumis melo) fruit tissue. The form I enzyme showed preferred activity with raffinose and significant activity with stachyose. Other unique characteristics of this enzyme, such as weak product inhibition by galactose (in contrast to the other ?-galactosidases, which show stronger product inhibition), also impart physiological significance. Using raffinose and stachyose as substrates in the assays, the activities of the three ?-galactosidases (alkaline form I, alkaline form II, and the acid form) were measured at different stages of fruit development. The form I enzyme activity increased during the early stages of ovary development and fruit set, in contrast to the other ?-galactosidase enzymes, both of which declined in activity during this period. In the mature, sucrose-accumulating mesocarp, the alkaline form I enzyme was the major ?-galactosidase present. We also observed hydrolysis of raffinose at alkaline conditions in enzyme extracts from other cucurbit sink tissues, as well as from young Coleus blumei leaves. Our results suggest different physiological roles for the ?-galactosidase forms in the developing cucurbit fruit, and show that the newly discovered enzyme plays a physiologically significant role in photoassimilate partitioning in cucurbit sink tissue. PMID:10069835

Gao, Zhifang; Schaffer, Arthur A.

1999-01-01

123

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

PubMed

An alkali tolerant Bacillus strain having extracellular serine alkaline protease activity was newly isolated from compost and identified as Bacillus clausii GMBE 22. An alkaline protease (AP22) was 4.66-fold purified in 51.5% yield from Bacillus clausii GMBE 22 by ethanol precipitation and DEAE-cellulose anion exchange chromatography. The purified enzyme was identified as serine protease by LC-ESI-MS analysis. Its complete inhibition by phenylmethanesulfonylfluoride (PMSF) also justified that it is a serine alkaline protease. The molecular weight of the enzyme is 25.4 kDa. Optimal temperature and pH values are 60 degrees C and 12.0, respectively. The enzyme showed highest specificity to N-Suc-Ala-Ala-Pro-Phe-pNA. The K(m) and k(cat) values for hydrolysis of this substrate are 0.347 mM and 1141 min(-1) respectively. The enzyme was affected by surface active agents to varying extents. The enzyme is stable for 2 h at 30 degrees C and pH 10.5. AP22 is also stable for 5 days over the pH range 9.0-11.0 at room temperature. AP22 has good pH stability compared with the alkaline proteases belonging to other strains of Bacillus clausii reported in the literature. PMID:19431045

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

2009-01-01

124

2nd Generation Alkaline Electrolysis FORCE Technology  

E-print Network

1 2nd Generation Alkaline Electrolysis FORCE Technology GreenHydrogen.dk. Technical University).................................................................................................... 12 4.4. Improved electrolysis stacks architecture (WP4

Mosegaard, Klaus

125

Kinetic determination of alkaline phosphatase activity based on hydrolytic cleavage of the P-F bond in monofluorophosphate and fluoride ion-selective electrode.  

PubMed

Alkaline phosphatase catalyzes the hydrolytic cleavage of the P-F bond in monofluorophosphate with the subsequent release of fluoride ions. A kinetic potentiometric method is described in which a fluoride ion-selective electrode is used for the sensitive and selective measurement of the released F- for the determination of alkaline phosphatase activity. It is shown that monofluorophosphate can be used as an alternative substrate for alkaline phosphatase. The reaction demonstrates a well-defined correlation with the hydrolysis of the P-O bond in 4-nitrophenyl phosphate. The serum alkaline phosphatase was determined in human serum samples by the potentiometric technique, and the results obtained compared well with a standard spectrophotometric method. PMID:2077934

Venetz, W P; Mangan, C; Siddiqi, I W

1990-11-15

126

Alkaline and alkaline earth metal phosphate halides and phosphors  

SciTech Connect

Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

2012-11-13

127

Cellulose hydrolysis in subcritical and supercritical water  

Microsoft Academic Search

In this paper we propose a new method to hydrolyze cellulose rapidly in supercritical water (SCW) to recover glucose, fructose and oligomers (cellobiose, cellotriose, cellotetraose, etc.). Cellulose decomposition experiments were conducted with a flow type reactor in the range of temperature from 290 to 400°C at 25MPa. A high pressure slurry feeder was developed to feed the cellulose–water slurries. Hydrolysis

Mitsuru Sasaki; Bernard Kabyemela; Roberto Malaluan; Satoshi Hirose; Naoko Takeda; Tadafumi Adschiri; Kunio Arai

1998-01-01

128

Enzymatic hydrolysis of spent coffee ground.  

PubMed

Spent coffee ground (SCG) is the main residue generated during the production of instant coffee by thermal water extraction from roasted coffee beans. This waste is composed mainly of polysaccharides such as cellulose and galactomannans that are not solubilised during the extraction process, thus remaining as unextractable, insoluble solids. In this context, the application of an enzyme cocktail (mannanase, endoglucanase, exoglucanase, xylanase and pectinase) with more than one component that acts synergistically with each other is regarded as a promising strategy to solubilise/hydrolyse remaining solids, either to increase the soluble solids yield of instant coffee or for use as raw material in the production of bioethanol and food additives (mannitol). Wild fungi were isolated from both SCG and coffee beans and screened for enzyme production. The enzymes produced from the selected wild fungi and recombinant fungi were then evaluated for enzymatic hydrolysis of SCG, in comparison to commercial enzyme preparations. Out of the enzymes evaluated on SCG, the application of mannanase enzymes gave better yields than when only cellulase or xylanase was utilised for hydrolysis. The recombinant mannanase (Man1) provided the highest increments in soluble solids yield (17 %), even when compared with commercial preparations at the same protein concentration (0.5 mg/g SCG). The combination of Man1 with other enzyme activities revealed an additive effect on the hydrolysis yield, but not synergistic interaction, suggesting that the highest soluble solid yields was mainly due to the hydrolysis action of mannanase. PMID:23436225

Jooste, T; García-Aparicio, M P; Brienzo, M; van Zyl, W H; Görgens, J F

2013-04-01

129

HYDROLYSIS RATE CONSTANTS FOR ENHANCING PROPERTY-REACTIVITY RELATIONSHIPS  

EPA Science Inventory

Rate constants for hydrolysis in water of ten classes of organic compounds are examined with the objective of establishing new, or expanding existing, property reactivity correlations. These relationships then can be used to predict the environmental hydrolysis of chemicals that ...

130

Catalytic peptide hydrolysis by mineral surface: Implications for prebiotic chemistry  

E-print Network

Catalytic peptide hydrolysis by mineral surface: Implications for prebiotic chemistry Karina concentration to mineral surface area. The rate of pyrite catalysis of GGG hydrolysis was found to be saturable

Sverjensky, Dimitri A.

131

Closed type alkaline storage battery  

SciTech Connect

The alkaline storage battery employs a metallic hat shaped terminal closure which has a piercing needle as well as a puncturable metallic diaphragm positioned below the piercing needle. The needle is fixed by caulking at its peripheral edge portion to a edge of the closure. A comparatively thick and hard metal plate is placed on the inner surface of the diaphragm and is applied to an open portion of a tubular metallic container which has a battery element. A peripheral edge portion of the closure, the diaphragm and the metallic plate are clamped in airtight relationship through a packing between the caulked end portion and an inner annular step portion of the metallic container of the battery. A lead wire extends from one polarity electrode of the battery element and is connected to a central portion of the metallic plate.

Hayama, H.

1980-06-10

132

The Alkaline Denaturation of DNA  

PubMed Central

A kinetic study of the alkaline transition of DNA, in clearly defined physico-chemical conditions, is presented, which allows us to identify, within the alkaline transition region, different pH ranges, corresponding to different ratelimiting factors. This analysis brings into consideration three distinct intervals of time which characterize the whole process, namely the time necessary for full hyperchromicity to be reached, the time required for strand separation in the case of a single DNA molecule, and the time for complete denaturation to be reached in the case of a DNA solution. The results obtained from ultracentrifugal, and spectrophotometric measurements, involving rapid mixing experiments, seem to indicate the following conclusions: whereas, in the lower pH ranges considered within the transition region, the denaturation process is limited by the first time constant, this same constant becomes extremely short at higher pH. On the other hand the fact that, in the higher pH range, the second and third time constants do not coincide (the time to unwind a single T2 DNA molecule being at least one order of magnitude shorter than the time required for bulk denaturation to be reached) suggests that in this pH range the overall denaturation rate is limited by a statistical process governing the initiation of unwinding. These observations are discussed in terms of a model in which the unwinding energy is given by the electrostatic repulsions which originate in the deprotonated DNA molecule. The model itself suggests some experiment which seem to confirm it. ImagesFigure 2Figure 3 PMID:4982056

Ageno, M.; Dore, E.; Frontali, C.

1969-01-01

133

Alkaline assisted thermal oil recovery: Kinetic and displacement studies  

SciTech Connect

This report deals with two major issues of chemical assisted flooding - the interaction of caustic, one of the proposed additives to steam flood, with the reservoir rock, and the displacement of oil by a chemical flood at elevated temperatures. A mathematical model simulating the kinetics of silica dissolution and hydroxyl ion consumption in a typical alkaline flooding environment is first developed. The model is based on the premise that dissolution occurs via hydrolysis of active sites through the formation of an intermediate complex, which is in equilibrium with the silicic acid in solution. Both static (batch) and dynamic (core flood) processes are simulated to examine the sensitivity of caustic consumption and silica dissolution to process parameters, and to determine rates of propagation of pH values. The model presented provides a quantitative description of the quartz-alkali interaction in terms of pH, salinity, ion exchange properties, temperature and contact time, which are of significant importance in the design of soluble silicate flooding processes. The modeling of an adiabatic hot waterflood assisted by the simultaneous injection of a chemical additive is next presented. The model is also applicable to the hot alkaline flooding under conditions of negligible adsorption of the generated anionic surfactant and of hydroxide adsorption being Langmuirian. The theory of generalized simple waves (coherence ) is used to develop solutions for the temperature, concentration, and oil saturation profiles, as well as the oil recovery curves. It is shown that, for Langmuir adsorption kinetics, the chemical resides in the heated region of the reservoir if its injection concentration is below a critical value, and in the unheated region if its concentration exceeds this critical value. Results for a chemical slug injection in a tertiary recovery process indicate recovery performance is maximized when chemical resides in the heated region of the reservior.

Saneie, S.; Yortsos, Y.C.

1993-06-01

134

Coupling of actin hydrolysis and polymerization: Reduced description with two  

E-print Network

OFFPRINT Coupling of actin hydrolysis and polymerization: Reduced description with two nucleotide of actin hydrolysis and polymerization: Reduced description with two nucleotide states X. Li1,2 , R to the hydrolysis of adenosine triphosphate (ATP), which involves both the cleavage of ATP and the release

Kierfeld, Jan

135

Actin Polymerization Overshoots and Hydrolysis as Assayed by Pyrene Fluorescence  

E-print Network

Actin Polymerization Overshoots and Hydrolysis as Assayed by Pyrene Fluorescence F. J. Brooks and A in different ATP hydrolysis states are not consistent with experimental data. This strong sensitivity of intensity to hydrolysis state implies that a measured pyrene intensity curve does not im- mediately reveal

Carlsson, Anders

136

Effects of microtubule mechanics on hydrolysis and catastrophes  

E-print Network

Effects of microtubule mechanics on hydrolysis and catastrophes N Müller and J Kierfeld Department modeling steric constraints to investigate the influence of mechanical forces on hydrolysis bending angle, which changes from °0 to °22 by hydrolysis of a dimer. This also affects the lateral

Kierfeld, Jan

137

ATP Hydrolysis Stimulates Large Length Fluctuations in Single Actin Filaments  

E-print Network

ATP Hydrolysis Stimulates Large Length Fluctuations in Single Actin Filaments Evgeny B. Stukalin is investigated theoretically using a stochastic model that takes into account the hydrolysis of ATP filaments. It is found that the ATP hydrolysis has a strong effect on dynamic properties of single actin

138

Energy Optimization of Bioethanol Production via Hydrolysis of Switchgrass  

E-print Network

1 Energy Optimization of Bioethanol Production via Hydrolysis of Switchgrass Mariano Martín, via hydrolysis. A superstructure embedding a number of alternatives is proposed. Two technologies of the grass is broken down. Next, enzymatic hydrolysis follows any of the pretreaments to obtain fermentable

Grossmann, Ignacio E.

139

Synergistic Catalysis of Dimetilan Hydrolysis by Metal Ions and  

E-print Network

Synergistic Catalysis of Dimetilan Hydrolysis by Metal Ions and Organic Ligands C H I N G - H U A H, The Johns Hopkins University, Baltimore, Maryland 21218 Hydrolysis of the insecticide dimetilan, which ion-organic ligandsynergisticeffectsonthedegradationofagrochemicals. Dimetilan hydrolysis is strongly

Huang, Ching-Hua

140

Unconventional Relationshipsfor Hemicellulose Hydrolysis and Subsequent Cellulose Digestion  

E-print Network

Chapter 6 Unconventional Relationshipsfor Hemicellulose Hydrolysis and Subsequent Cellulose and subsequently by enzymatic hydrolysis of the residual cellulose, and these sugars can be used to produce fuels for such biological routes, and we seek to better understand hydrolysis kinetics to support emerging applications

California at Riverside, University of

141

FRONTIERS ARTICLE On the hydration and hydrolysis of carbon dioxide  

E-print Network

FRONTIERS ARTICLE On the hydration and hydrolysis of carbon dioxide Alice H. England a,b , Andrew M August 2011 a b s t r a c t The dissolution of carbon dioxide in water and the ensuing hydrolysis, and hydration strength. Ã? 2011 Elsevier B.V. All rights reserved. 1. Introduction The hydrolysis of carbon

Cohen, Ronald C.

142

Atomic and molecular spectra of vapors evolved in a graphite furnace. Part 4: alkaline earth chlorides  

NASA Astrophysics Data System (ADS)

Dry residues of aqueous solutions of alkaline earth chlorides (100 ?g as element) were vaporized in the Ta-lined and pyrocoated graphite furnace during temperature ramp from 400° to 2400-2500°C. Absorption and emission spectra were obtained in the 200-475 nm range using a dedicated CCD spectrometer. BeCl 2 in aqueous solutions showed an almost complete hydrolysis prior to the vaporization. The spectra were characterized by the contemporaneous presence of intense light scattering and emission continuum, in analogy with the behavior of Be(NO 3) 2 already examined. By applying BeCl 2 slurry in chloroform enabled the observation of BeCl 2 and BeCl species in the vapor phase. Aqueous solution of MgCl 2 showed the evolution of di-halide species at low temperatures and the vaporization pattern with the emission continuum and light scattering similar to that observed for Mg(NO 3) 2 at higher temperature. The hydrolysis of the di-chlorides decreases for the alkaline earth elements with increasing of atomic mass. The Ca, Sr and Ba chlorides showed a vaporization pattern of di-chloride in both a pyrocoated and Ta-lined tube with increased simultaneous appearance of mono-chloride and atomic species in the pyrocoated tube. The proposed explanation indicates a trend to the decomposition due to the sample vapor interaction with graphite.

Katskov, Dmitri A.; Mofolo, Rita M.; Tittarelli, Paolo

2001-01-01

143

Effect of four pretreatments on enzymatic hydrolysis and ethanol fermentation of wheat straw. Influence of inhibitors and washing.  

PubMed

Pretreatment is essential in the production of alcohol from lignocellulosic material. In order to increase enzymatic sugar release and bioethanol production, thermal, dilute acid, dilute basic and alkaline peroxide pretreatments were applied to wheat straw. Compositional changes in pretreated solid fractions and sugars and possible inhibitory compounds released in liquid fractions were analysed. SEM analysis showed structural changes after pretreatments. Enzymatic hydrolysis and fermentation by Pichia stipitis of unwashed and washed samples from each pretreatment were performed so as to compare sugar and ethanol yields. The effect of the main inhibitors found in hydrolysates (formic acid, acetic acid, 5-hydroxymethylfurfural and furfural) was first studied through ethanol fermentations of model media and then compared to real hydrolysates. Hydrolysates of washed alkaline peroxide pretreated biomass provided the highest sugar concentrations, 31.82g/L glucose, and 13.75g/L xylose, their fermentation yielding promising results, with ethanol concentrations reaching 17.37g/L. PMID:24531149

Toquero, Cristina; Bolado, Silvia

2014-04-01

144

Inorganic-organic separators for alkaline batteries  

NASA Technical Reports Server (NTRS)

A flexible separator is reported for use between the electrodes of Ni-Cd and Ni-Zn batteries using alkaline electrolytes. The separator was made by coating a porous substrate with a battery separator composition. The coating material included a rubber-based resin copolymer, a plasticizer and inorganic and organic fillers which comprised 55% by volume or less of the coating as finally dried. One or more of the filler materials, whether organic or inorganic, is preferably active with the alkaline electrolyte to produce pores in the separator coating. The plasticizer was an organic material which is hydrolyzed by the alkaline electrolyte to improve conductivity of the separator coating.

Sheibley, D. W. (inventor)

1978-01-01

145

Process for extracting technetium from alkaline solutions  

DOEpatents

A process for extracting technetium values from an aqueous alkaline solution containing at least one alkali metal hydroxide and at least one alkali metal nitrate, the at least one alkali metal nitrate having a concentration of from about 0.1 to 6 molar. The solution is contacted with a solvent consisting of a crown ether in a diluent for a period of time sufficient to selectively extract the technetium values from the aqueous alkaline solution. The solvent containing the technetium values is separated from the aqueous alkaline solution and the technetium values are stripped from the solvent.

Moyer, Bruce A. (Oak Ridge, TN); Sachleben, Richard A. (Knoxville, TN); Bonnesen, Peter V. (Knoxville, TN)

1995-01-01

146

Alkaline sorbent injection for mercury control  

DOEpatents

A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Madden, Deborah A. (Boardman, OH); Holmes, Michael J. (Washington Township, Stark County, OH)

2002-01-01

147

Alkaline sorbent injection for mercury control  

DOEpatents

A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Madden, Deborah A. (Boardman, OH); Holmes, Michael J. (Washington Township, Stark County, OH)

2003-01-01

148

Effects of microtubule mechanics on hydrolysis and catastrophes  

E-print Network

We introduce a model for microtubule mechanics containing lateral bonds between dimers in neighboring protofilaments, bending rigidity of dimers, and repulsive interactions between protofilaments modeling steric constraints to investigate the influence of mechanical forces on hydrolysis and catastrophes. We use the allosteric dimer model, where tubulin dimers are characterized by an equilibrium bending angle, which changes from $0^\\circ$ to $22^\\circ$ by hydrolysis of a dimer. This also affects the lateral interaction and bending energies and, thus, the mechanical equilibrium state of the microtubule. As hydrolysis gives rise to conformational changes in dimers, mechanical forces also influence the hydrolysis rates by mechanical energy changes modulating the hydrolysis rate. The interaction via the microtubule mechanics then gives rise to correlation effects in the hydrolysis dynamics, which have not been taken into account before. Assuming a dominant influence of mechanical energies on hydrolysis rates, we i...

Müller, Nina

2014-01-01

149

?-cyclodextrin assistant flavonoid glycosides enzymatic hydrolysis  

PubMed Central

Background: The content of icaritin and genistein in herba is very low, preparation with relatively large quantities is an important issue for extensive pharmacological studies. Objective: This study focuses on preparing and enzymic hydrolysis of flavonoid glycosides /?-cyclodextrin inclusion complex to increase the hydrolysis rate. Materials and Methods: The physical property of newly prepared inclusion complex was tested by differential scanning calorimetry (DSC). The conditions of enzymatic hydrolysis were optimized for the bioconversion of flavonoid glycosides /?-cyclodextrin inclusion complex by mono-factor experimental design. The experiments are using the icariin and genistein as the model drugs. Results: The solubility of icariin and genistein were increased almost 17 times from 29.2 ?g/ml to 513.5 ?g/ml at 60°C and 28 times from 7.78 ?g/ml to 221.46 ?g/ml at 50°C, respectively, demonstrating that the inclusion complex could significantly increase the solubility of flavonoid glycosides. Under the optimal conditions, the reaction time of icariin and genistin decreased by 68% and 145%, when compared with that without ?-CD inclusion. By using this enzymatic condition, 473 mg icaritin (with the purity of 99.34%) and 567 mg genistein(with the purity of 99.46%), which was finally determined by melt point, ESI-MS, UV, IR, 1H NMR and 13C NMR, was obtained eventually by transforming the inclusion complex(contains 1.0 g substrates). Conclusion: This study can clearly indicate a new attempt to improve the speed of enzyme-hydrolysis of poorly water-soluble flavonoid glycosides and find a more superior condition which is used to prepare icaritin and genistein. PMID:24143039

Jin, Xin; Zhang, Zhen-hai; Sun, E.; Jia, Xiao-Bin

2013-01-01

150

Fungal secretomes enhance sugar beet pulp hydrolysis  

PubMed Central

The recalcitrance of lignocellulose makes enzymatic hydrolysis of plant biomass for the production of second generation biofuels a major challenge. This work investigates an efficient and economic approach for the enzymatic hydrolysis of sugar beet pulp (SBP), which is a difficult to degrade, hemicellulose-rich by-product of the table sugar industry. Three fungal strains were grown on different substrates and the production of various extracellular hydrolytic and oxidative enzymes involved in pectin, hemicellulose, and cellulose breakdown were monitored. In a second step, the ability of the culture supernatants to hydrolyze thermally pretreated SBP was tested in batch experiments. The supernatant of Sclerotium rolfsii, a soil-borne facultative plant pathogen, was found to have the highest hydrolytic activity on SBP and was selected for further hydrolyzation experiments. A low enzyme load of 0.2 mg g–1 protein from the culture supernatant was sufficient to hydrolyze a large fraction of the pectin and hemicelluloses present in SBP. The addition of Trichoderma reesei cellulase (1–17.5 mg g–1 SBP) resulted in almost complete hydrolyzation of cellulose. It was found that the combination of pectinolytic, hemicellulolytic, and cellulolytic activities works synergistically on the complex SBP composite, and a combination of these hydrolytic enzymes is required to achieve a high degree of enzymatic SBP hydrolysis with a low enzyme load. PMID:24677771

Kracher, Daniel; Oros, Damir; Yao, Wanying; Preims, Marita; Rezic, Iva; Haltrich, Dietmar; Rezic, Tonci; Ludwig, Roland

2014-01-01

151

Composite seal reduces alkaline battery leakage  

NASA Technical Reports Server (NTRS)

Composite seal consisting of rubber or plastic washers and a metal washer reduces alkaline battery leakage. Adhesive is applied to each washer interface, and the washers are held together mechanically.

Clatterbuck, C. H.; Plitt, K. F.

1965-01-01

152

Synthesis of nonionic-anionic colloidal systems based on alkaline and ammonium ?-nonylphenol polyethyleneoxy (n?=?3-20) propionates/dodecylbenzenesulfonates with prospects for food hygiene  

PubMed Central

Background The main objective of this work was to obtain a binary system of surface-active components (nonionic soap – alkaline and/or ammonium dodecylbenzenesulfonate) with potential competences in food hygiene, by accessing a scheme of classical reactions (cyanoethylation, total acid hydrolysis and stoichiometric neutralization with inorganic alkaline and/or organic ammonium bases) adapted to heterogeneously polyethoxylated nonylphenols (n?=?3-20). In the processing system mentioned, dodecylbenzenesulfonic acid, initially the acid catalyst for the exhaustive hydrolysis of ?-nonylphenolpolyethyleneoxy (n?=?3-20) propionitriles, becomes together with the nonionic soap formed the second surface-active component of the binary system. Results In the reaction scheme adopted the influence of the main operating (duration, temperature, molar ratio of reagents) and structural parameters (degree of oligomerization of the polyoxyethylene chain) on the processing yields for the synthetic steps was followed. The favorable role of the polyoxyethylene chain size is remarked, through its specific conformation and its alkaline cations sequestration competences on the yields of cyanoethylation, but also the beneficial influence of phase-transfer catalysts in the total acid hydrolysis step. The chemical stability of dodecylbenzenesulfonic acid (DBSH) at the temperature and strongly acidic pH of the reaction environment is confirmed. The controlled change of the amount of DBSH in the final binary system will later confer it potential colloidal competences in food hygiene receipts. Conclusions The preliminary synthetic tests performed confirmed the prospect of obtaining a broad range of useful colloidal competences in various food hygiene scenarios. PMID:22958389

2012-01-01

153

Alkaline tolerant dextranase from streptomyces anulatus  

DOEpatents

A process for production of an alkaline tolerant dextranase enzyme comprises culturing a dextran-producing microorganism Streptomyces anulatus having accession no. ATCC PTA-3866 to produce an alkaline tolerant dextranase, Dex 1 wherein the protein in said enzyme is characterized by a MW of 63.3 kDa and Dex 2 wherein its protein is characterized by a MW of 81.8 kDa.

Decker, Stephen R. (Berthoud, CO); Adney, William S. (Golden, CO); Vinzant, Todd B. (Golden, CO); Himmel, Michael E. (Littleton, CO)

2003-01-01

154

Effect of hydrolysis time on the physicochemical and functional properties of corn glutelin by Protamex hydrolysis.  

PubMed

The physicochemical and functional properties, such as surface hydrophobicity, disulphide bond content, thermal properties, molecular weight distribution, antioxidant properties, of corn glutelin hydrolysates catalysed by Protamex at different hydrolysis times were evaluated. The hydrolysis influenced the properties of corn glutelin significantly, and not only decreased its molecular weight and disulphide bond content, but also eventually transformed its insoluble native aggregates to soluble aggregates during the hydrolysis process. Corn glutelin hydrolysates were found to have a higher solubility, which was associated with their relatively higher foaming and emulsifying properties compared to the original glutelin. Corn glutelin and its hydrolysates maintained a high thermal stability. In addition, the hydrolysates exhibited excellent antioxidant properties measured through in vitro assays, namely DPPH and OH radical scavenging activity, Fe(2+)-chelating capacity and reducing power; the values were 58.86%, 82.64%, 29.92% and 0.236% at 2.0mg/mL, respectively. PMID:25442571

Zheng, Xi-qun; Wang, Jun-tong; Liu, Xiao-lan; Sun, Ying; Zheng, Yong-jie; Wang, Xiao-jie; Liu, Yue

2015-04-01

155

Organosolv pretreatment for enzymatic hydrolysis of poplars: I. enzyme hydrolysis of cellulosic residues  

SciTech Connect

Aspen (Populus tremuloides) and black cottonwood (Populus trichocarpa) organosolv pulps produced in a wide range of solvent composition (between 30 and 70% by volume of methanol) and catalysts (H/sub 2/SO/sub 4/ and H/sub 3/PO/sub 4/) such that the cooking liquor pH less than or equal to 3 are easily digested by enzymes. The total yields of hydrolysis residues (pulps) are in the 40-60% range; the acid-catalyzed delignification followed by enzyme hydrolysis can generate 70-88% of the original six-carbon sugars contained in the wood. Glucomannan and arabinogalactan are dissolved in to the pulping liquor in the pH range of 2-4.5. Lower pH (less than or equal to 3) leads to additional solubilization of six-carbon sugars. These sugars may be fermented directly. From the insoluble hydrolysis residues, 36-41% conversions of wood into fermentable sugars were obtained after enzyme hydrolysis; the starting feedstocks contain 50.8 and 46.6% hexosans, respectively, for aspen and black cottonwood. The kinetics of enzymatic hydrolysis of cellulose can be formally treated as two simultaneous pseudo-first-order reactions in which fast and slow hydrolysis of cellulose occur. Correlations between the glucan digestibility and the effect of the pretreatment have been made. The higher residual xylan content reduces the amount of the rapidly hydrolyzable glucan fraction and lowers the glucan digestibility. The proposed simple kinetic treatment is very helpful in assessing the effect of the pretreatment on pulp enzyme hydrolyzability.

Chum, H.L.; Johnson, D.K.; Black, S.; Baker, J.; Grohmann, K.; Sarkanen, K.V.; Wallace, K.; Schroeder, H.A.

1988-01-01

156

Effects of microtubule mechanics on hydrolysis and catastrophes  

E-print Network

We introduce a model for microtubule mechanics containing lateral bonds between dimers in neighboring protofilaments, bending rigidity of dimers, and repulsive interactions between protofilaments modeling steric constraints to investigate the influence of mechanical forces on hydrolysis and catastrophes. We use the allosteric dimer model, where tubulin dimers are characterized by an equilibrium bending angle, which changes from $0^\\circ$ to $22^\\circ$ by hydrolysis of a dimer. This also affects the lateral interaction and bending energies and, thus, the mechanical equilibrium state of the microtubule. As hydrolysis gives rise to conformational changes in dimers, mechanical forces also influence the hydrolysis rates by mechanical energy changes modulating the hydrolysis rate. The interaction via the microtubule mechanics then gives rise to correlation effects in the hydrolysis dynamics, which have not been taken into account before. Assuming a dominant influence of mechanical energies on hydrolysis rates, we investigate the most probable hydrolysis pathways both for vectorial and random hydrolysis. Investigating the stability with respect to lateral bond rupture, we identify initiation configurations for catastrophes along the hydrolysis pathways and values for a lateral bond rupture force. If we allow for rupturing of lateral bonds between dimers in neighboring protofilaments above this threshold force, our model exhibits avalanche-like catastrophe events.

Nina Müller; Jan Kierfeld

2014-06-05

157

Properties of an Alkaline Phosphatase from Sinclair Swine Melanoma  

Microsoft Academic Search

In Sinclair swine, there is an increase in alkaline phosphatase activity in spontaneously arising melanoma tumors when compared to normal skin. While alkaline phosphatase activity could be detected in melanomas from animals 1 day old, the maximum levels of alkaline phosphatase activity occurred in tumors from animals greater than 30 days old. The alkaline phosphatase was purified from cutaneous melanomas

Marshall V. Williams; Reuel R. Hook

1984-01-01

158

Computational modeling of the catalytic mechanism of human placental alkaline phosphatase (PLAP).  

PubMed

Alkaline phosphatases (APs) catalyze the hydrolysis and transphosphorylation of phosphate monoesters. Quantum mechanical, molecular dynamics, and molecular docking techniques were applied to computationally model the catalytic mechanism of human placental AP (PLAP). Kinetic and thermodynamic evaluations were performed for each reaction step. The functional significances of the more important residues within the active site were analyzed. The role of the metal ion at the metal binding site M3 was also examined. The calculated activation and reaction energy and free energy values obtained suggested the nucleophilic attack of the Ser92 alkoxide on the phosphorus atom of the substrate would be the rate-limiting step of the catalytic hydrolysis of alkyl phosphate monoesters by PLAP. The reactivities of the wild-type M3-Mg enzyme and the M3-Zn protein were compared, and the main difference observed was a change in the coordination number of the M3 metal for the M3-Zn enzyme. This modification in the active site structure lowered the free energy profile for the second chemical step of the catalytic mechanism (hydrolysis of the covalent phosphoserine intermediate). Consequently, a greater stabilization of the phosphoseryl moiety resulted in a small increment in the activation free energy of the phosphoserine hydrolysis reaction. These computational results suggest that the activation of APs by magnesium at the M3 site is caused by the preference of Mg(2+) for octahedral coordination, which structurally stabilizes the active site into a catalytically most active conformation. The present theoretical results are in good agreement with previously reported experimental studies. PMID:21939286

Borosky, Gabriela L; Lin, Susana

2011-10-24

159

An improved method for basic hydrolysis of isoflavone malonylglucosides and quality evaluation of Chinese soy materials.  

PubMed

Basic hydrolysis procedure is often included in the sample preparation in order to quantify malonylglucosides or acetylglucosides of soy materials. However, it is preferable not to use NaOH as a hydrolytic reagent considering the effect of its alkalinity on the successive injection to HPLC and low acidity of soy isoflavones. This paper presents an improved method for basic hydrolysis using ammonia as a hydrolytic reagent without the additional neutralization step. Moreover, by means of HPLC and LC-MS methods, a systematic quality evaluation of natural soy materials from Chinese markets were established and discussed, inclusive of soybeans, black soybeans, defatted soy flours, as well as the distribution of isoflavones in the seed coat, hypocotyl and cotyledon. The results indicate that HPLC profiling patterns of originating various isoflavone constituents of Chinese soybeans was similar to those of Japanese ones, and those of Chinese black soybeans was similar to those of American ones. The average content level of total soy isoflavones of Chinese soybeans and black soybeans were a little lower than that of American and Japanese ones. Additionally, the thorough analysis for Semen Sojae Praeparatum, a Chinese herbal medicine made from fermented black soybeans or soybeans was done for the first time and the characteristic of its HPLC profiling patterns shows the higher content of isoflavone glucosides and aglycones than those of natural soy materials. PMID:18175965

Yuan, Dan; Pan, Yingni; Chen, Yan; Uno, Toshio; Zhang, Shaohui; Kano, Yoshihiro

2008-01-01

160

Impact of Cell Wall Acetylation on Corn Stover Hydrolysis by Cellulolytic and Xylanolytic Enzymes  

SciTech Connect

Analysis of variously pretreated corn stover samples showed neutral to mildly acidic pretreatments were more effective at removing xylan from corn stover and more likely to maintain the acetyl to xylopyranosyl ratios present in untreated material than were alkaline treatments. Retention of acetyl groups in the residual solids resulted in greater resistance to hydrolysis by endoxylanase alone, although the synergistic combination of endoxylanase and acetyl xylan esterase enzymes permitted higher xylan conversions to be observed. Acetyl xylan esterase alone did little to improve hydrolysis by cellulolytic enzymes, although a direct relationship was observed between the enzymatic removal of acetyl groups and improvements in the enzymatic conversion of xylan present in substrates. In all cases, effective xylan conversions were found to significantly improve glucan conversions achievable by cellulolytic enzymes. Additionally, acetyl and xylan removal not only enhanced the respective initial rates of xylan and glucan conversion, but also the overall extents of conversion. This work emphasizes the necessity for xylanolytic enzymes during saccharification processes and specifically for the optimization of acetyl esterase and xylanase synergies when biomass processes include milder pretreatments, such as hot water or sulfite steam explosion.

Selig, M. J.; Adney, W. S.; Himmel, M. E.; Decker, S. R.

2009-01-01

161

Catalysts for the hydrolysis of thiophosphate triesters  

E-print Network

of similar basicity and are often referred to as supernucleophiles. Because of their relatively low pKa, these species exist in their deprotonated nucleophilic form even at low pH?s. 7 I O O OH I O O I O O O - I O O HO O - O O 5 67 (IBA)8 (IBX... hydrolysis is also largely enhanced by the addition of oximate anions such as benzaldoximes (14, figure 8) and pyridinealdoxime (15, figure 8) in presence of the cationic surfactants (CTACL). 23 These oximes posses a rather high pKa (9-12) which leads...

Picot, Alexandre

2005-02-17

162

Improved method for detection of starch hydrolysis  

SciTech Connect

A new starch hydrolysis detection method which does not rely on iodine staining or the use of color-complexed starch is described. A linear relationship was obtained with agar-starch plates when net clearing zones around colonies of yeasts were plotted against enzyme levels (semilogarithm scale) produced by the same yeast strains in liquid medium. A similar relationship between starch clearing zones and alpha-amylase levels from three different sources was observed. These observations suggest that the method is useful in mutant isolations, strain improvement programs, and the prediction of alpha-amylase activities in culture filtrates or column effluents. (Refs. 18).

Ohawale, M.R.; Wilson, J.J.; Khachatourians, G.G.; Ingledew, W.M.

1982-09-01

163

Pretreatment and enzymatic hydrolysis of lignocellulosic biomass  

NASA Astrophysics Data System (ADS)

The performance of soybean hulls and forage sorghum as feedstocks for ethanol production was studied. The main goal of this research was to increase fermentable sugars' yield through high-efficiency pretreatment technology. Soybean hulls are a potential feedstock for production of bio-ethanol due to their high carbohydrate content (?50%) of nearly 37% cellulose. Soybean hulls could be the ideal feedstock for fuel ethanol production, because they are abundant and require no special harvesting and additional transportation costs as they are already in the plant. Dilute acid and modified steam-explosion were used as pretreatment technologies to increase fermentable sugars yields. Effects of reaction time, temperature, acid concentration and type of acid on hydrolysis of hemicellulose in soybean hulls and total sugar yields were studied. Optimum pretreatment parameters and enzymatic hydrolysis conditions for converting soybean hulls into fermentable sugars were identified. The combination of acid (H2SO4, 2% w/v) and steam (140°C, 30 min) efficiently solubilized the hemicellulose, giving a pentose yield of 96%. Sorghum is a tropical grass grown primarily in semiarid and dry parts of the world, especially in areas too dry for corn. The production of sorghum results in about 30 million tons of byproducts mainly composed of cellulose, hemicellulose, and lignin. Forage sorghum such as brown midrib (BMR) sorghum for ethanol production has generated much interest since this trait is characterized genetically by lower lignin concentrations in the plant compared with conventional types. Three varieties of forage sorghum and one variety of regular sorghum were characterized and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-Ray diffraction were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and enzymatic hydrolysis process. Up to 72% of hexose yield and 94% of pentose yield were obtained using "modified" steam explosion with 2% sulfuric acid at 140°C for 30 min and enzymatic hydrolysis with cellulase (15 FPU/g cellulose) and beta-glucosidase (50 CBU/g cellulose).

Corredor, Deisy Y.

164

Hydrolysis of Baltic amber during thermal ageing--an infrared spectroscopic approach.  

PubMed

To enable conservation of amber in museums, understanding of chemical changes is crucial. While oxidation has been investigated particularly well for this natural polymer, further degradation phenomena in relation to humidity and pollutants are poorly studied or still unknown. Attenuated total reflectance-Fourier transform infrared spectroscopy was explored with regard to Baltic amber. A systematic spectroscopic survey of a wide range of thermally aged model amber samples, exposed to different microclimatic conditions, showed significant changes in their spectra. Samples aged in a humid and acidic environment or exposed to a humid and alkaline atmosphere generally exhibited a higher absorbance intensity of carbonyl groups at frequencies assigned to acids than unaged samples, samples aged in drier conditions and samples immersed in an alkaline solution. Baltic amber comprises succinate ester, which may be hydrolysed into communol and succinic acid. The survey thus provided evidence about the progress of hydrolytic reactions during degradation of Baltic amber. Infrared spectroscopy was shown to have significant potential for providing qualitative and quantitative chemical information on hydrolysis of amber, which will be of interest for the development of preventive conservation techniques for museum collections of amber objects. PMID:23376267

Pastorelli, Gianluca; Shashoua, Yvonne; Richter, Jane

2013-04-01

165

Hydrolysis of Baltic amber during thermal ageing - An infrared spectroscopic approach  

NASA Astrophysics Data System (ADS)

To enable conservation of amber in museums, understanding of chemical changes is crucial. While oxidation has been investigated particularly well for this natural polymer, further degradation phenomena in relation to humidity and pollutants are poorly studied or still unknown. Attenuated total reflectance-Fourier transform infrared spectroscopy was explored with regard to Baltic amber. A systematic spectroscopic survey of a wide range of thermally aged model amber samples, exposed to different microclimatic conditions, showed significant changes in their spectra. Samples aged in a humid and acidic environment or exposed to a humid and alkaline atmosphere generally exhibited a higher absorbance intensity of carbonyl groups at frequencies assigned to acids than unaged samples, samples aged in drier conditions and samples immersed in an alkaline solution. Baltic amber comprises succinate ester, which may be hydrolysed into communol and succinic acid. The survey thus provided evidence about the progress of hydrolytic reactions during degradation of Baltic amber. Infrared spectroscopy was shown to have significant potential for providing qualitative and quantitative chemical information on hydrolysis of amber, which will be of interest for the development of preventive conservation techniques for museum collections of amber objects.

Pastorelli, Gianluca; Shashoua, Yvonne; Richter, Jane

2013-04-01

166

Enhanced enzymatic hydrolysis of pretreated almond-tree prunings for sugar production.  

PubMed

Almond-tree prunings (ATP), an agricultural residue largely available in Mediterranean countries, were pretreated with either hot water or dilute sulphuric acid at 180-230 °C. Solids derived from hot water pretreatments were further submitted to alkaline peroxide delignification. In addition, all solids obtained from the three mentioned processes were hydrolysed by cellulases and ?-glucosidases to investigate their enzymatic digestibilities. Hot water pretreatment led to high oligosaccharide yields (18.2 g/100 g ATP at 190 °C) while dilute acid pretreatment provided the highest monosaccharide yields (24.0 g/100 g ATP at 190 °C) along with low concentrations of fermentation inhibitors. Glucose yields from enzymatic hydrolysis were strongly affected by both pretreatment type and pretreatment temperature. The highest temperature assayed for both hydrothermal and dilute sulphuric acid pretreatment maximized the glucose recovery (49.2% and 72.8%, respectively) while solids derived from alkaline peroxide treatment achieved maximal glucose concentrations (41.9 g/L, 58.4% of potential yield). PMID:24274571

Cuevas, Manuel; García, Juan Francisco; Sánchez, Sebastián

2014-01-01

167

ESTIMATION OF PHOSPHATE ESTER HYDROLYSIS RATE CONSTANTS. II. ACID AND GENERAL BASE CATALYZED HYDROLYSIS  

EPA Science Inventory

SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate acid and neutral hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition states of a ...

168

Effect of gelatinization and hydrolysis conditions on the selectivity of starch hydrolysis with alpha-amylase from Bacillus licheniformis.  

PubMed

Enzymatic hydrolysis of starch can be used to obtain various valuable hydrolyzates with different compositions. The effects of starch pretreatment, enzyme addition point, and hydrolysis conditions on the hydrolyzate composition and reaction rate during wheat starch hydrolysis with alpha-amylase from Bacillus licheniformis were compared. Suspensions of native starch or starch gelatinized at different conditions either with or without enzyme were hydrolyzed. During hydrolysis, the oligosaccharide concentration, the dextrose equivalent, and the enzyme activity were determined. We found that the hydrolyzate composition was affected by the type of starch pretreatment and the enzyme addition point but that it was just minimally affected by the pressure applied during hydrolysis, as long as gelatinization was complete. The differences between hydrolysis of thermally gelatinized, high-pressure gelatinized, and native starch were explained by considering the granule structure and the specific surface area of the granules. These results show that the hydrolyzate composition can be influenced by choosing different process sequences and conditions. PMID:18095648

Baks, Tim; Bruins, Marieke E; Matser, Ariette M; Janssen, Anja E M; Boom, Remko M

2008-01-23

169

Evolutionary alkaline transition in human cytochrome c.  

PubMed

Conformational transitions in cytochrome c (cyt c) are being realized to be responsible for its multi-functions. Among a number of conformational transitions in cyt c, the alkaline transition has attracted much attention. The cDNA of human cyt c is cloned by RT-PCR and a high-effective expression system for human cyt c has been developed in this study. The equilibrium and kinetics of the alkaline transition of human cyt c have been systematically investigated for the first time, and compared with those of yeast and horse cyt c from an evolutionary perspective. The pK(a) value for the alkaline transition of human cyt c is apparently higher than that of yeast and horse. Kinetic studies suggest that it is increasingly difficult for the alkaline transition of cyt c from yeast, horse and human. Molecular modeling of human cyt c shows that the omega loop where the lysine residue is located apparently further away from heme in human cyt c than in yeast iso-1 and horse heart cyt c. These results regarding alkaline conformational transition provide valuable information for understanding the molecular basis for the biological multi-functions of cyt c. PMID:19593652

Ying, Tianlei; Zhong, Fangfang; Xie, Jin; Feng, Yanjiao; Wang, Zhong-Hua; Huang, Zhong-Xian; Tan, Xiangshi

2009-06-01

170

Hydrolysis of lignocelluloses by penicillium funiculosum cellulase  

SciTech Connect

Enzymatic hydrolysis of cellulose is a promising method for the conversion of waste cellulose to glucose. During the past few years, the development of this technology has proceeded rapidly, with significant advances made in enzyme production, pretreatment, and hydrolysis. A variety of fungi are reported to produce cellulases but among these Trichoderma reesei and its mutants are powerful producers of cellulases. However, the search for new and possibly better sources of cellulase is continued due to the low levels of beta-glucosidase of T. reesei. Penicillium funiculosum produces a complete cellulase having endo-beta-1,4-glucanase (15-20 U/mL), exo-beta-1,4-glucanase (1.5-2.0 U/mL), and high beta-glucosidase (8-10 U/mL). The saccharification of alkali-treated cotton and bagasse by P. funiculosum enzyme was 70 and 63%, respectively. It was possible to obtain glucose concentration as high as 30% using 50% bagasse. It is of interest that the percent saccharification of cellulosic substrates with the Penicillium enzyme is comparable to that of T. reesei cellulase when the same amount of filter paper activity is used, although the endo-glucanase activity of the latter is two to three times higher. This communication reports the studies on saccharification of lignocelluloses by P. funiculosum cellulase and certain studies on the kinetic aspects. (Refs. 15).

Mishra, C.; Rao, M.; Seeta, R.; Srinivasan, M.C.; Deshpande, V.

1984-04-01

171

Differential expression of alkaline and neutral invertases in response to environmental stresses: characterization of an alkaline isoform as a stress-response enzyme in wheat leaves.  

PubMed

It is well accepted that sucrose (Suc) metabolism is involved in responses to environmental stresses in many plant species. In the present study we showed that alkaline invertase (A-Inv) expression is up-regulated in wheat leaves after an osmotic stress or a low-temperature treatment. We demonstrated that the increase of total alkaline/neutral Inv activity in wheat leaves after a stress could be due to the induction of an A-Inv isoform. Also, we identified and functionally characterized the first wheat cDNA sequence that codes for an A-Inv. The wheat leaf full-length sequence encoded a protein 70% similar to a neutral Inv of Lolium temulentum; however, after functional characterization, it resulted to encode a protein that hydrolyzed Suc to hexoses with an optimum pH of 8, and, consequently, the encoding sequence was named Ta-A-Inv. By RT-PCR assays we demonstrated that Ta-A-Inv expression is induced in response to osmotic and cold stress in mature primary wheat leaves. We propose that Ta-A-Inv activity could play an important role associated with a more efficient cytosolic Suc hydrolysis during environmental stresses. PMID:17674033

Vargas, Walter A; Pontis, Horacio G; Salerno, Graciela L

2007-11-01

172

The acid and enzymic hydrolysis of O-acetylated sialic acid residues from rabbit Tamm–Horsfall glycoprotein  

PubMed Central

Rabbit Tamm–Horsfall glycoprotein and bovine submaxillary glycoprotein were both found to contain sialic acid residues which are released at a slow rate by the standard conditions of acid hydrolysis. These residues are also resistant to neuraminidases from Vibrio cholerae and Clostridium perfringens. This behaviour was attributed to the presence of O-acetylated sialic acid, since the removal of O-acetyl groups by mild alkaline treatment normalized the subsequent release of sialic acid from rabbit Tamm–Horsfall glycoprotein by acid and by enzymic hydrolysis. Determination of the O-acetyl residues in rabbit Tamm–Horsfall glycoprotein indicated that on average two hydroxyl groups of sialic acid are O-acetylated, and these were located on the polyhydroxy side-chain of sialic acid or on C-4 and C-8. These findings confirm the assumption that certain O-acetylated forms of sialic acid are not substrates for bacterial neuraminidases. Several explanations have been suggested to explain the effect of O-acetylation of the side-chain on the rate of acidcatalysed hydrolysis of sialic acid residues. PMID:4349114

Neuberger, A.; Ratcliffe, Wendy A.

1972-01-01

173

The effect of varying organosolv pretreatment chemicals on the physicochemical properties and cellulolytic hydrolysis of mountain pine beetle-killed lodgepole pine.  

PubMed

Mountain pine beetle-killed lodgepole pine (Pinus contorta) chips were pretreated using the organosolv process, and their ease of subsequent enzymatic hydrolysis was assessed. The effect of varying pretreatment chemicals and solvents on the substrate's physicochemical characteristics was also investigated. The chemicals employed were MgCl2, H2SO4, SO2, and NaOH, and the solvents were ethanol and butanol. It was apparent that the different pretreatments resulted in variations in both the chemical composition of the solid and liquid fractions as well in the extent of cellulolytic hydrolysis (ranging from 21% to 82% hydrolysis after 12 h). Pretreatment under acidic conditions resulted in substrates that were readily hydrolyzed despite the apparent contradiction that pretreatment under alkaline conditions resulted in increased delignification (approximately 7% and 10% residual lignin for alkaline conditions versus 17% to 19% for acidic conditions). Acidic pretreatments also resulted in lower cellulose degree of polymerization, shorter fiber lengths, and increased substrate porosity. The substrates generated when butanol/water mixtures were used as the pretreatment solvent were also hydrolyzed more readily than those generated with ethanol/water. This was likely due to the limited miscibility of the solvents resulting in an increased concentration of pretreatment chemicals in the aqueous layer and thus a higher pretreatment severity. PMID:19820908

Del Rio, Luis F; Chandra, Richard P; Saddler, Jack N

2010-05-01

174

Industrial-scale steam explosion pretreatment of sugarcane straw for enzymatic hydrolysis of cellulose for production of second generation ethanol and value-added products.  

PubMed

Steam explosion at 180, 190 and 200°C for 15min was applied to sugarcane straw in an industrial sugar/ethanol reactor (2.5m(3)). The pretreated straw was delignificated by sodium hydroxide and hydrolyzed with cellulases, or submitted directly to enzymatic hydrolysis after the pretreatment. The pretreatments led to remarkable hemicellulose solubilization, with the maximum (92.7%) for pretreatment performed at 200°C. Alkaline treatment of the pretreated materials led to lignin solubilization of 86.7% at 180°C, and only to 81.3% in the material pretreated at 200°C. All pretreatment conditions led to high hydrolysis conversion of cellulose, with the maximum (80.0%) achieved at 200°C. Delignification increase the enzymatic conversion (from 58.8% in the cellulignin to 85.1% in the delignificated pulp) of the material pretreated at 180°C, but for the material pretreated at 190°C, the improvement was less remarkable, while for the pretreated at 200°C the hydrolysis conversion decreased after the alkaline treatment. PMID:23306125

Oliveira, Fernando M V; Pinheiro, Irapuan O; Souto-Maior, Ana M; Martin, Carlos; Gonçalves, Adilson R; Rocha, George J M

2013-02-01

175

Photoelastic response of alkaline earth aluminosilicate glasses.  

PubMed

Understanding the structural origins of the photoelastic response in oxide glasses is important for discovering new families of zero-stress optic glasses and for developing a predictive physical model. In this Letter, we have investigated the composition dependence of the stress optic coefficient C of 32 sodium aluminosilicate glasses with different types of alkaline earth oxides (MgO, CaO, SrO, and BaO). We find that most of the composition dependence of the stress optic response can be captured by a linear regression model and that the individual contributions from the alkaline earths to C depend on the alkaline earth-oxygen bond metallicity. High bond metallicity is required to allow bonds to be distorted along both the bonding direction and perpendicular to it. These findings are valuable for understanding the photoelastic response of oxide glasses. PMID:22297330

Smedskjaer, Morten M; Saxton, Scott A; Ellison, Adam J; Mauro, John C

2012-02-01

176

Alkaline earth filled nickel skutterudite antimonide thermoelectrics  

DOEpatents

A thermoelectric material including a body centered cubic filled skutterudite having the formula A.sub.xFe.sub.yNi.sub.zSb.sub.12, where A is an alkaline earth element, x is no more than approximately 1.0, and the sum of y and z is approximately equal to 4.0. The alkaline earth element includes guest atoms selected from the group consisting of Be, Mb, Ca, Sr, Ba, Ra and combinations thereof. The filled skutterudite is shown to have properties suitable for a wide variety of thermoelectric applications.

Singh, David Joseph

2013-07-16

177

Alkaline Capacitors Based on Nitride Nanoparticles  

NASA Technical Reports Server (NTRS)

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

Aldissi, Matt

2003-01-01

178

40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...  

Code of Federal Regulations, 2012 CFR

...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...oxirane, substituted silylmethyl-, hydrolysis products with alkanol...

2012-07-01

179

40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...  

Code of Federal Regulations, 2013 CFR

...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...oxirane, substituted silylmethyl-, hydrolysis products with alkanol...

2013-07-01

180

40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...  

Code of Federal Regulations, 2010 CFR

...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...oxirane, substituted silylmethyl-, hydrolysis products with alkanol...

2010-07-01

181

Reaction Dynamics of ATP Hydrolysis Catalyzed by P-Glycoprotein  

PubMed Central

P-glycoprotein (P-gp) is a member of the ABC transporter family that confers drug resistance to many tumors by catalyzing their efflux, and it is a major component of drug–drug interactions. P-gp couples drug efflux with ATP hydrolysis by coordinating conformational changes in the drug binding sites with the hydrolysis of ATP and release of ADP. To understand the relative rates of the chemical step for hydrolysis and the conformational changes that follow it, we exploited isotope exchange methods to determine the extent to which the ATP hydrolysis step is reversible. With ?18O4-labeled ATP, no positional isotope exchange is detectable at the bridging ?-phosphorus–O??-phosphorus bond. Furthermore, the phosphate derived from hydrolysis includes a constant ratio of three 18O/two 18O/one 18O that reflects the isotopic composition of the starting ATP in multiple experiments. Thus, H2O-exchange with HPO42– (Pi) was negligible, suggesting that a [P-gp·ADP·Pi] is not long-lived. This further demonstrates that the hydrolysis is essentially irreversible in the active site. These mechanistic details of ATP hydrolysis are consistent with a very fast conformational change immediately following, or concomitant with, hydrolysis of the ?-phosphate linkage that ensures a high commitment to catalysis in both drug-free and drug-bound states. PMID:24506763

2015-01-01

182

Ultrasound Enhancement of Enzymatic Hydrolysis of Cellulose Plant Matter  

Technology Transfer Automated Retrieval System (TEKTRAN)

The work reported here is based on acceleration of enzymatic hydrolysis of plant biomass substrate by introduction of low intensity, uniform ultrasound field into a reaction chamber (bio-reactor). This method may serve as improvement of rates in the hydrolysis of cellulosic materials to sugars, whi...

183

Mechanism of surfactant effect in enzymatic hydrolysis of lignocellulose  

Microsoft Academic Search

Lignocellulose is a potential substrate for ethanol production. However, high cellulose conversion requires high enzyme loading, which makes the process less economically feasible. Addition of surfactants to enzymatic hydrolysis of lignocellulose increases the conversion of cellulose into soluble sugars. The mechanism is not known for the increase of lignocellulose hydrolysis by surfactant addition, therefore, experiments were designed to explore mechanisms

Torny Eriksson; Johan Börjesson; Folke Tjerneld

2002-01-01

184

Class Projects in Physical Organic Chemistry: The Hydrolysis of Aspirin  

ERIC Educational Resources Information Center

An exercise that provides a hands-on demonstration of the hydrolysis of aspirin is presented. The key to understanding the hydrolysis is recognizing that all six process may occur simultaneously and that the observed rate constant is the sum of the rate constants that one rate constant dominates the overall process.

Marrs, Peter S.

2004-01-01

185

Pre-Steady-State Analysis of ATP Hydrolysis by Saccharomyces cereVisiae DNA Topoisomerase II. 2. Kinetic Mechanism for the Sequential Hydrolysis of Two  

E-print Network

Pre-Steady-State Analysis of ATP Hydrolysis by Saccharomyces cereVisiae DNA Topoisomerase II. 2. Kinetic Mechanism for the Sequential Hydrolysis of Two ATP Timothy T. Harkins,,| Timothy J. Lewis) sequential ATP hydrolysis or (2) simultaneous hydrolysis of both ATP. Here, we present results

Lewis, Timothy

186

Effects of Alkaline Phosphatase Activity on Nucleotide Measurements in Aquatic Microbial Communities †  

PubMed Central

Alkaline phosphatase (APase) activity was detected in aquatic microbial assemblages from the subtropics to Antarctica. The occurrence of APase in environmental nucleotide extracts was shown to significantly affect the measured concentrations of cellular nucleotides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, guanosine triphosphate, uridine triphosphate, and cytidine triphosphate), adenylate energy charge, and guanosine triphosphate/adenosine triphosphate ratios, when conventional methods of nucleotide extraction were employed. Under the reaction conditions specified in this report, the initial rate of hydrolysis of adenosine triphosphate was directly proportional to the activity of APase in the sample extracts and consequently can be used as a sensitive measure of APase activity. A method was devised for obtaining reliable nucleotide measurements in naturally occurring microbial populations containing elevated levels of APase activity. The metabolic significance of APase activity in microbial cells is discussed, and it is concluded that the occurrence and regulation of APase in nature is dependent upon microscale inorganic phosphate limitation of the autochthonous microbial communities. PMID:16345634

Karl, D. M.; Craven, D. B.

1980-01-01

187

A sensitive enzyme-catalytic nanogold-resonance scattering spectral assay for alkaline phosphate.  

PubMed

In pH 8.9 Tris-HCl buffer solutions, alkaline phosphatase (ALP) catalyzed the hydrolysis of ascorbic acid 2-phosphate (AAP) substrate to form ascorbic acid. Then H(3)PO(4) was added to stop the enzymatic reaction and HAuCl(4) was used to react with ascorbic acid to generate gold nanoparticles that exhibited a resonance scattering (RS) peak at 600 nm. Under the selected conditions, when the activity of ALP increased, the formed ascorbic acid and gold nanoparticles also increased. Thus, the RS intensity at 600 nm enhanced linearly. The linear range was 0.06-22 U/L, with a detection limit of 0.03 U/L. The ALP in serum was analyzed, and the results were in agreement with those of the fluorescence method. PMID:22113359

Jiang, Zhiliang; Wu, Meng; Liu, Gaosan; Liang, Aihui

2012-06-01

188

Near-infrared fluorescence probe for the determination of alkaline phosphatase.  

PubMed

Water-soluble CuInS2 quantum dots (QDs) were directly synthesized in an aqueous solution with mercaptopropionic acid (MPA) as stabilizers, and were functionalized using tryptophan molecules to form tryptophan-functionalized CuInS2 QDs (W-CuInS2 QDs) that had a strong fluorescence emission around 689 nm. The fluorescence of W-CuInS2 QDs could be quenched by Cu(2+) and then the addition of pyrophosphate (PPi) could effectively turn on the quenched fluorescence due to the strong interaction between Cu(2+) and PPi. The alkaline phosphatase (ALP) could catalyze the hydrolysis of PPi that would disassemble the complex of PPi-Cu(2+)-PPi. Therefore, the recovered fluorescence could be quenched again by the addition of ALP. In this paper, we developed a novel near-infrared fluorescence probe for the simple and convenient assay of ALP. PMID:24388906

Liu, Siyu; Pang, Shu; Na, Weidan; Su, Xingguang

2014-05-15

189

The Effect of Alkaline Pretreatment Methods on Cellulose Structure and Accessibility.  

PubMed

The effects of different alkaline pretreatments on cellulose structural features and accessibility are compared and correlated with the enzymatic hydrolysis of Populus. The pretreatments are shown to modify polysaccharides and lignin content to enhance the accessibility for cellulase enzymes. The highest increase in the cellulose accessibility was observed in dilute sodium hydroxide, followed by methods using ammonia soaking and lime (Ca(OH)2 ). The biggest increase of cellulose accessibility occurs during the first 10?min of pretreatment, with further increases at a slower rate as severity increases. Low temperature ammonia soaking at longer residence times dissolved a major portion of hemicellulose and exhibited higher cellulose accessibility than high temperature soaking. Moreover, the most significant reduction of degree of polymerization (DP) occurred for dilute sodium hydroxide (NaOH) and ammonia pretreated Populus samples. The study thus identifies important cellulose structural features and relevant parameters related to biomass recalcitrance. PMID:25421020

Bali, Garima; Meng, Xianzhi; Deneff, Jacob I; Sun, Qining; Ragauskas, Arthur J

2014-11-24

190

[Cytotoxicity test based on luminescent assay of alkaline phosphatase released from target cells].  

PubMed

Assay of 51Cr release from target cells has been commonly used in various methods of examining the cytotoxic properties of lymphocytes. In this paper a non-isotopic assay of cytotoxicity based on the leak of endogenous alkaline phosphatase (AIP) in target cells, is described. Enzyme activities were assayed by the luminescence on hydrolysis of the lumigen-PPD substrate. P3-X63-Ag8-U1 (P3U-1) cells were demonstrated to contain AIP and proved sensitive to the IL-2-induced killer lymphocytes, while no AIP activity was detected in human effector lymphocytes. Comparative studies of the test with 51Cr- and AIP-release in P3U-1 target cells were carried out, and the results obtained suggested that the AIP release test is useful as a new, simple lymphocyte cytotoxicity test. PMID:7996714

Kasatori, N; Urayama, T; Mori, T; Ishikawa, F

1994-10-01

191

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

PubMed Central

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

Schwalfenberg, Gerry K.

2012-01-01

192

Catalytic Zinc Complexes for Phosphate Diester Hydrolysis*  

PubMed Central

Creating efficient artificial catalysts that can compete with biocatalysis has been an enduring challenge which has yet to be met. Reported herein is the synthesis and characterization of a series of zinc complexes designed to catalyze the hydrolysis of phosphate diesters. By introducing a hydrated aldehyde into the ligand we achieve turnover for DNA-like substrates which, combined with ligand methylation, increases reactivity by two orders of magnitude. In contrast to current orthodoxy and mechanistic explanations, we propose a mechanism where the nucleophile is not coordinated to the metal ion, but involves a tautomer with a more effective Lewis acid and more reactive nucleophile. This data suggests a new strategy for creating more efficient metal ion based catalysts, and highlights a possible mode of action for metalloenzymes. PMID:24919567

Tirel, Emmanuel Y; Bellamy, Zoë; Adams, Harry; Lebrun, Vincent; Duarte, Fernanda; Williams, Nicholas H

2014-01-01

193

Fermentable sugars by chemical hydrolysis of biomass.  

PubMed

Abundant plant biomass has the potential to become a sustainable source of fuels and chemicals. Realizing this potential requires the economical conversion of recalcitrant lignocellulose into useful intermediates, such as sugars. We report a high-yielding chemical process for the hydrolysis of biomass into monosaccharides. Adding water gradually to a chloride ionic liquid-containing catalytic acid leads to a nearly 90% yield of glucose from cellulose and 70-80% yield of sugars from untreated corn stover. Ion-exclusion chromatography allows recovery of the ionic liquid and delivers sugar feedstocks that support the vigorous growth of ethanologenic microbes. This simple chemical process, which requires neither an edible plant nor a cellulase, could enable crude biomass to be the sole source of carbon for a scalable biorefinery. PMID:20194793

Binder, Joseph B; Raines, Ronald T

2010-03-01

194

Modeling of autocatalytic hydrolysis of adefovir dipivoxil in solid formulations.  

PubMed

The stability and hydrolysis kinetics of a phosphate prodrug, adefovir dipivoxil, in solid formulations were studied. The stability relationship between five solid formulations was explored. An autocatalytic mechanism for hydrolysis could be proposed according to the kinetic behavior which fits the Prout-Tompkins model well. For the classical kinetic models could hardly describe and predict the hydrolysis kinetics of adefovir dipivoxil in solid formulations accurately when the temperature is high, a feedforward multilayer perceptron (MLP) neural network was constructed to model the hydrolysis kinetics. The build-in approaches in Weka, such as lazy classifiers and rule-based learners (IBk, KStar, DecisionTable and M5Rules), were used to verify the performance of MLP. The predictability of the models was evaluated by 10-fold cross-validation and an external test set. It reveals that MLP should be of general applicability proposing an alternative efficient way to model and predict autocatalytic hydrolysis kinetics for phosphate prodrugs. PMID:21467805

Dong, Ying; Zhang, Yan; Xiang, Bingren; Deng, Haishan; Wu, Jingfang

2011-04-01

195

DNA-Catalyzed Hydrolysis of Esters and Aromatic Amides  

PubMed Central

We previously reported that DNA catalysts (deoxyribozymes) can hydrolyze DNA phosphodiester linkages, but DNA-catalyzed amide bond hydrolysis has been elusive. Here we used in vitro selection to identify DNA catalysts that hydrolyze ester linkages as well as DNA catalysts that hydrolyze aromatic amides, for which the leaving group is an aniline moiety. The aromatic amide-hydrolyzing deoxyribozymes were examined using linear free energy relationship analysis. The hydrolysis reaction is unaffected by substituents on the aromatic ring (? ? 0), suggesting general acid-catalyzed elimination as the likely rate-determining step of the addition-elimination hydrolysis mechanism. These findings establish that DNA has the catalytic ability to achieve hydrolysis of esters and aromatic amides as carbonyl-based substrates, and they suggest a mechanism-based approach to achieve DNA-catalyzed aliphatic amide hydrolysis. PMID:24127695

Brandsen, Benjamin M.; Hesser, Anthony R.; Castner, Marissa A.; Chandra, Madhavaiah

2013-01-01

196

[Enzymatic hydrolysis of cellulose in reverse micelles].  

PubMed

Several types of surfactants were adopted to construct reverse micelles, in order to investigate the characteristics of cellulose hydrolysis, we used the carboxymethyl cellulose as substrate. The electrical conductivity was measured to determine the maximum water solubilization W0( W0 = [H2O]/[SA] ) of CTAB, SDS, Tween-80 and rhamnolipid reverse micellar systems were 15.2, 20.1, 2.3 and 40.3. In this condition we studied the effects of surfactants concentrations and cellulose dosage on the enzymatic hydrolysis of reverse micelle,and compared with aqueous systems. It was shown by the results that when the cellulose dosage was 0.15 FPU/g substrate, the maximum yield of reducing sugar in reverse micelles was obtained at 1 cmc of CTAB, SDS, Tween-80 and rhamnolipid, in which the rhamnolipid yield was the highest of 198.03 mg substrate. When the concentrations of CTAB, SDS, Tween-80 and rhamnolipid were 1 cmc, the productions of reverse micelles systems were higher than that of aqueous systems of 34.36%, 21.24%, 11.44% and 34.62%. In the optimum conditions of the surfactant concentration, taking the saving cost and sugar yield into consideration, the cellulose dosage of 5 FPU substrate was the most suitable. The reducing sugar's yield of biosurfactant rhamnolipid reverse micellar system was higher than those of three chemical surfactant systems, it was shown that the adoption of biosurfactant has technologically promising prospect in constructing reverse micelles and enhancing the stability of reverse micelles. PMID:21072947

Wang, Wei-Wei; Yuan, Xing-Zhong; Zeng, Guang-Ming; Liang, Yun-Shan; Chao, Yang

2010-09-01

197

Simultaneous determination of hydrolysis and mutarotation rates during the enzymatic hydrolysis of lactose.  

PubMed

An experiment is described in which a custom-made glucose electrode is used to directly monitor the enzymatic hydrolysis of lactose to glucose. The transient profile of beta- d-glucose can be used to simultaneously determine the rate constants for mutarotation and for enzymatic hydrolysis by applying a dynamic nonlinear regression routine. Due to differences in the mutarotation rate constants between lactose and glucose, the beta- d-glucose concentration "overshoots" equilibrium under certain conditions, which can be modeled mathematically. This overshoot can be observed reliably and used to quantify the differences in mutarotational equilibria between glucose and lactose. These observations may be important for the analysis of dairy products and commercial lactase preparations and illustrate an unusual kinetic phenomenon caused by intramolecular forces. This approach may also be important for the accurate determination of a variety of oligosaccharides such as glycogen, which tend to be composed primarily of one stereoisomer. PMID:18712880

Jenkins, Daniel M; Teruel, Michael A; Reyes-de-Corcuera, José I; Young, Owen

2008-09-24

198

Dilute acid hydrolysis of paper birch: kinetics studies of xylan and acetyl-group hydrolysis.  

PubMed

Batch hydrolysis kinetics of paper birch (Betula papyrifera) xylan and its associated acetyl groups in dilute sulfuric acid have been measured for acid concentrations of between 0.04 and 0.18M and temperatures of between 100 and 170 degrees C. Only 5% of the cellulose was hydrolyzed for up to 85% xylan removal. Rate data were correlated well by a parallel reaction model based on the existence of reactive and resistant xylan portions. The resulting rate equation predicts the experimental xylan concentrations in the residue to within 10%. Hydrolysis of xylan-associated acetyl groups was found to occur at the same rate as that of xylan, except at 100 degrees C, where acetyl is released preferentially. No effect of acid concentration on the rate of acetyl removal relative to that of xylan was evident. PMID:18553680

Maloney, M T; Chapman, T W; Baker, A J

1985-03-01

199

40 CFR 721.10499 - Substituted silane, hydrolysis products with silica (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Substituted silane, hydrolysis products with silica (generic...721.10499 Substituted silane, hydrolysis products with silica (generic...identified generically as substituted silane, hydrolysis products with silica (PMNs...

2013-07-01

200

Application of High Throughput Pretreatment and Co-Hydrolysis System to Thermochemical  

E-print Network

Application of High Throughput Pretreatment and Co-Hydrolysis System to Thermochemical Pretreatment, Tennessee ABSTRACT: High throughput pretreatment (HTPH) and enzymatic hydrolysis systems are now vital and enzymatic hydrolysis conditions. Although hydrothermal pretreatment is currently being employed in most high

California at Riverside, University of

201

40 CFR 721.10498 - Substituted alkyl ester, hydrolysis products with silica (generic).  

Code of Federal Regulations, 2013 CFR

... false Substituted alkyl ester, hydrolysis products with silica (generic...10498 Substituted alkyl ester, hydrolysis products with silica (generic...generically as substituted alkyl ester, hydrolysis products with silica (PMNs...

2013-07-01

202

40 CFR 721.10497 - Substituted alkyl ester, hydrolysis products with silica and substituted silane (generic).  

... false Substituted alkyl ester, hydrolysis products with silica and substituted...10497 Substituted alkyl ester, hydrolysis products with silica and substituted...generically as substituted alkyl ester, hydrolysis products with silica and...

2014-07-01

203

40 CFR 721.10498 - Substituted alkyl ester, hydrolysis products with silica (generic).  

... false Substituted alkyl ester, hydrolysis products with silica (generic...10498 Substituted alkyl ester, hydrolysis products with silica (generic...generically as substituted alkyl ester, hydrolysis products with silica (PMNs...

2014-07-01

204

Hydrolysis of organonitrate functional groups in aerosol particles , John E. Shilling2  

E-print Network

Hydrolysis of organonitrate functional groups in aerosol particles Shang Liu1 , John E Drive, La Jolla CA, 92093-0221 Running title: Hydrolysis of organonitrates Keywords: organonitrate, organic nitrate, hydrolysis, secondary organic aerosol #12; Abstract Organonitrate (ON) groups

Russell, Lynn

205

40 CFR 721.10499 - Substituted silane, hydrolysis products with silica (generic).  

...2014-07-01 false Substituted silane, hydrolysis products with silica (generic...721.10499 Substituted silane, hydrolysis products with silica (generic...identified generically as substituted silane, hydrolysis products with silica (PMNs...

2014-07-01

206

40 CFR 721.10497 - Substituted alkyl ester, hydrolysis products with silica and substituted silane (generic).  

Code of Federal Regulations, 2013 CFR

... false Substituted alkyl ester, hydrolysis products with silica and substituted...10497 Substituted alkyl ester, hydrolysis products with silica and substituted...generically as substituted alkyl ester, hydrolysis products with silica and...

2013-07-01

207

MERCURIC CHLORIDE CAPTURE BY ALKALINE SORBENTS  

EPA Science Inventory

The paper gives results of bench-scale mechanistic studies of mercury/sorbent reactions that showed that mercuric chloride (HgC12) is readily adsorbed by alkaline sorbents, which may offers a less expensive alternative to the use of activated carbons. A laboratory-scale, fixed-b...

208

Negative Electrode For An Alkaline Cell  

DOEpatents

The present invention concerns a negative electrode for an alkaline cell, comprising a current collector supporting a paste containing an electrochemically active material and a binder, characterized in that said binder is a polymer containing hydrophilic and hydrophobic groups, said polymer being selected from an acrylic homopolymer, copolymer and terpolymer, an unsaturated organic acid copolymer and an unsaturated acid anhydride copolymer.

Coco, Isabelle (Talence Cedex, FR); Cocciantelli, Jean-Michel (Bordeaux, FR); Villenave, Jean-Jacques (Talence Cedex, FR)

1998-07-14

209

Alkaline earth metal catalysts for asymmetric reactions.  

PubMed

The group 2 alkaline earth metals calcium (Ca), strontium (Sr), and barium (Ba) are among the most common elements on Earth, abundant in both the sea and the Earth's crust. Although they are familiar in our daily lives, their application to organic synthesis has, so far, been limited. Some particularly useful properties of these elements include (i) low electronegativity, (ii) a stable oxidation state of +2, meaning that they can potentially form two covalent bonds with anions, and (iii) the ability to occupy a variety of coordination sites due to their large ionic radius. Furthermore, the alkaline earth metals, found between the group 1 and group 3 elements, show mild but significant Lewis acidity, which can be harnessed to control coordinative molecules via a Lewis acid-base interaction. Taken together, these characteristics make the metals Ca, Sr, and Ba very promising components of highly functionalized acid-base catalysts. In this Account, we describe the development of chiral alkaline earth metal catalysts for asymmetric carbon-carbon bond-forming reactions. Recently prepared chiral alkaline earth metal complexes have shown high diastereo- and enantioselectivities in fundamental and important chemical transformations. We chose chiral bisoxazoline (Box) derivatives bearing a methylene tether as a ligand for chiral modification. These molecules are very useful because they can covalently coordinate to alkaline earth metals in a bidentate fashion through deprotonation of the tether portion. It was found that chiral calcium-Box complexes could successfully promote catalytic asymmetric 1,4-addition and [3 + 2] cycloaddition reactions with high diastereo- and enantioselectivities. Both the calcium-Box complexes and chiral strontium-bis-sulfonamide and chiral barium-BINOLate complexes could catalyze asymmetric 1,4-addition reactions with high enantioselectivities. Furthermore, we designed a calcium-neutral coordinative ligand complex as a new type of chiral alkaline earth metal catalyst. We found that pyridinebisoxazolines (Pybox) worked well: they served as excellent ligands for calcium compounds in 1,4-addition reactions and Mannich reactions. Moreover, they were successful in 1,4-additions in concert with enantioselective protonation, affording the desired products in good to high enantioselectivities. Our results demonstrate that alkaline earth metals are very useful and attractive catalysts in organic synthesis. Moreover, their ubiquity in the environment is a distinct advantage over rare metals for large-scale processes, and their minimal toxicity is beneficial in both handling and disposal. PMID:20979379

Kobayashi, Sh?; Yamashita, Yasuhiro

2011-01-18

210

ACTINIDE-ALUMINATE SPECIATION IN ALKALINE RADIOACTIVE WASTE  

EPA Science Inventory

Highly alkaline radioactive waste tanks contain a number of transuranic species, in particular U, Np, Pu, and Am - the exact forms of which are currently unknown. Knowledge of actinide speciation under highly alkaline conditions is essential towards understanding and predicting ...

211

Increase in the Export of Alkalinity from North America's  

E-print Network

, or terrestrial alkalinity (carbonate and bicarbonate ions) produced during chemical weathering in soils can- tural practices. The production of alkalinity through chem- ical weathering in soils sequesters atmo#12;Increase in the Export of Alkalinity from North America's Largest River Peter A. Raymond1

Berkowitz, Alan R.

212

Ultrafast hydrolysis of a lewis photoacid.  

PubMed

This study explores the concept that electronic excitation can dramatically enhance Lewis acidity. Specifically, it is shown that photoexcitation transforms an electron-deficient organic compound of negligible Lewis acidity in its electronic ground state into a potent excited-state Lewis acid that releases a proton from a nearby water molecule in 3.1 ps. It was shown previously (Peon et al. J. Phys. Chem. A 2001, 105, 5768) that the excited state of methyl viologen (MV(2+)) is quenched rapidly in aqueous solution with the formation of an unidentified photoproduct. In this study, the quenching mechanism and the identity of the photoproduct were investigated by the femtosecond transient absorption and fluorescence upconversion techniques. Transient absorption signals at UV probe wavelengths reveal a long-lived species with a pH-dependent lifetime due to reaction with hydronium ions at a bimolecular rate of 3.1 × 10(9) M(-1) s(-1). This species is revealed to be a charge-transfer complex consisting of a ground-state MV(2+) ion and a hydroxide ion formed when a water molecule transfers a proton to the bulk solvent. Formation of a contact ion pair between MV(2+) and hydroxide shifts the absorption spectrum of the former ion by a few nm to longer wavelengths, yielding a transient absorption spectrum with a distinctive triangle wave appearance. The slight shift of this spectrum, which is in excellent agreement with steady-state difference spectra recorded for MV(2+) at high pH, is consistent with an ion pair but not with a covalent adduct (pseudobase). The long lifetime of the ion pair at neutral pH indicates that dissociation occurs many orders of magnitude more slowly than predicted by the Smoluchowski-Debye equation. Remarkably, there is no evidence of geminate recombination, suggesting that the proton that is transferred to the solvent is conducted at least several water shells away. Although the hydrolysis mechanism has yet to be fully established, evidence suggests that the strongly oxidizing excited state of MV(2+) triggers the proton-coupled oxidation of a water molecule. The observed kinetic isotope effect of 1.7 seen in D2O vs H2O is of the magnitude expected for an ultrafast concerted proton-electron transfer reaction. The ultrafast hydrolysis seen here may be a general excited-state quenching mechanism for electronically excited Lewis acids and other powerful photooxidants in aqueous solution. PMID:25510461

Henrich, Joseph D; Suchyta, Scott; Kohler, Bern

2015-02-12

213

Matrix diffusion of some alkali- and alkaline earth-metals in granitic rock  

SciTech Connect

Static through-diffusion experiments were performed to study the diffusion of alkali- and alkaline earth-metals in fine-grained granite and medium-grained Aespoe-diorite. Tritiated water was used as an inert reference tracer. Radionuclides of the alkali- and alkaline earth-metals (mono- and divalent elements which are not influenced by hydrolysis in the pH-range studied) were used as tracers, i.e., {sup 22}Na{sup +}, {sup 45}Ca{sup 2+} and {sup 85}Sr{sup 2+}. The effective diffusivity and the rock capacity factor were calculated by fitting the breakthrough curve to the one-dimensional solution of the diffusion equation. Sorption coefficients, K{sub d}, that were derived from the rock capacity factor (diffusion experiments) were compared with K{sub d} determined in batch experiments using crushed material of different size fractions. The results show that the tracers were retarded in the same order as was expected from the measured batch K{sub d}. Furthermore, the largest size fraction was the most representative when comparing batch K{sub d} with K{sub d} evaluated from the diffusion experiments. The observed effective diffusivities tended to decrease with increasing cell lengths, indicating that the transport porosity decreases with increasing sample lengths used in the diffusion experiments.

Johansson, H.; Byegaard, J.; Skarnemark, G.; Skaalberg, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Nuclear Chemistry

1997-12-31

214

Stereoselective hydrolysis catalyzed by a Bacillus endoglucanase in family D.  

PubMed

An endoglucanase in family D, purified from a strain of Bacillus, was found to catalyze the hydrolysis of p-nitrophenyl beta-D-cellotrioside to generate alpha-cellobiose, as determined by 1H-NMR spectroscopy. The hydrolysis of the beta-1,4 glucosidic bond by the enzyme proceeds, therefore, by an inversion mechanism. Furthermore, the interconversion of the alpha- and beta-anomeric protons in the products of hydrolysis, after equilibrium had been reached by mutarotation, was directly characterized by magnetization transfer NMR experiment that exploited the truncated driven nuclear Overhauser effect. PMID:7626068

Kawaminami, S; Ozaki, K; Ito, S

1995-07-17

215

Vibrational spectroscopic studies in the hydrolysis and condensation of chlorotrimethylsilane.  

PubMed

Raman and infrared spectroscopy were used to study the hydrolysis and condensation of chlorotrimethylsilane (CTMC) in aqueous organic solvents. From the recorded spectra and their intensity variation with time, we were able to identify trimethylsilanol as the reaction intermediate or the hydrolysis product as well as hexamethyldisiloxane (HMDS) as the final condensation product. The measured Raman intensity of CTMS at different time revealed that hydrolysis of CTMS is first order in terms of the CTMS concentration. From the Raman spectra collected under different conditions, it was noted that condensation reaction rates is faster in neutral condition than in acidic condition. PMID:15036105

Li, Ying-Sing; Le, Kim

2004-03-01

216

Vibrational spectroscopic studies in the hydrolysis and condensation of chlorotrimethylsilane  

NASA Astrophysics Data System (ADS)

Raman and infrared spectroscopy were used to study the hydrolysis and condensation of chlorotrimethylsilane (CTMC) in aqueous organic solvents. From the recorded spectra and their intensity variation with time, we were able to identify trimethylsilanol as the reaction intermediate or the hydrolysis product as well as hexamethyldisiloxane (HMDS) as the final condensation product. The measured Raman intensity of CTMS at different time revealed that hydrolysis of CTMS is first order in terms of the CTMS concentration. From the Raman spectra collected under different conditions, it was noted that condensation reaction rates is faster in neutral condition than in acidic condition.

Li, Ying-Sing; Le, Kim

2004-03-01

217

Polarized light-stimulated enzymatic hydrolysis of chitin and chitosan.  

PubMed

Illumination with white linearly polarized light (WLPL) stimulated chitinase and chitosanase in their degradation of chitin and chitosan, respectively. Enzymes were illuminated at room temperature in separate vessels, then admixed in reactors containing polysaccharides. Hydrolysis of chitosan to glucosamine followed first order kinetics whereas hydrolysis of chitin to N-acetylglucosamine deviated from the first order kinetics. In both cases, an increase in the rate of hydrolysis depended on the illumination time. Efficient degradation required up to 60 min exposure of the enzyme to WLPL. PMID:18823881

Konieczna-Molenda, Anna; Fiedorowicz, Maciej; Zhong, Wei; Tomasik, Piotr

2008-12-01

218

Effect of Ultrasonic Frequency on Enzymatic Hydrolysis of Cellulose  

NASA Astrophysics Data System (ADS)

The effect of ultrasonic frequency on the enzymatic hydrolysis of cellulose was examined. As the cellulose and enzyme, needle unbleached kraft pulp and cellulase were used. In the cases of the horn-type transducer at 20 kHz and the plate-type transducer at 28 kHz, the enzymatic hydrolysis was accelerated by ultrasonic irradiation. Total sugar concentration linearly increased with ultrasonic intensity. On the other hand, in the case of the plate-type transducer at 500 kHz, the enzymatic hydrolysis was inhibited. Total sugar concentration decreased with increasing ultrasonic intensity.

Keiji Yasuda,; Daiki Kato,; Zheng Xu,; Makiko Sakka,; Kazuo Sakka,

2010-07-01

219

Hydrolysis and Partial Recycling of a Chloroaluminate Ionic Liquid  

PubMed Central

Hydrolysis of the ionic liquid Et3NHCl-2AlCl3 and a process for recycling the triethylamine were studied. When the hydrolysis was carried out at a relatively high temperature, the released HCl could be absorbed more easily. With addition of sodium hydroxide to the aqueous hydrolysis solution, a feasible process for recycling triethylamine was developed, involving first distillation of triethylamine, followed by filtration of the aluminium hydroxide. The yield of recovered triethylamine was about 95%. The triethylhydrogenammonium chloride prepared from the recycled triethylamine was of good purity and could be reused to synthesize new chloroaluminate ionic liquids.

Fang, Ming-Hong; Wang, Li-Sheng

2007-01-01

220

Enhanced recovery of alkaline protease from fish viscera by phase partitioning and its application  

PubMed Central

Background Too many different protein and enzyme purification techniques have been reported, especially, chromatographic techniques. Apart from low recovery, these multi-step methods are complicated, time consuming, high operating cost. So, alternative beneficially methods are still required. Since, the outstanding advantages of aqueous two phase system (ATPS) such as simple, low cost, high recovery and scalable, ATPS have been used to purify various enzymes. To improve purification efficiency, parameters affected to enzyme recovery or purity was investigated. The objectives of the present study were to optimize of alkaline protease recovery from giant catfish fish viscera by using ATPS and to study of hydrolytic patterns against gelatin. Results Using 70% (w/w) crude enzyme extract (CE) in system (15% PEG2000-15% sodium citrate) provided the highest recovery, PF and KE. At unmodified pH (8.5) gave the best recovery and PF with compare to other pHs of the system. The addition of 1% (w/w) NaCl showed the recovery (64.18%), 3.33-fold and 15.09 of KE compared to the system without NaCl. After addition of 10% (w/w) sodium citrate in the second ATPS cycle, the highest protease recovery (365.53%) and PF (11.60-fold) were obtained. Thus, the top phase from the system was subjected to further studied. The protein bands with molecular weights (MWs) of 20, 24, 27, 36, 94 and 130 kDa appeared on the protein stained gel and also exhibited clear zone on casein-substrate gel electrophoresis. The ?, ?1, ?2 of skin gelatin extensively degraded into small molecules when treated with 10 units of the extracted alkaline protease compared to those of the level of 0.21 units of Flavourzyme. Conclusions Repetitive ATPS is the alternative strategy to increase both recovery and purity of the alkaline protease from farmed giant catfish viscera. Extracted alkaline protease exposed very high effectiveness in gelatin hydrolysis. It is suggested that the alkaline protease from this fish viscera can further be used in protein hydrolysate production. PMID:23631530

2013-01-01

221

Dilute acid hydrolysis of wheat straw oligosaccharides.  

PubMed

The dilute acid posthydrolysis of wheat straw hemicellulosic oligosaccharides obtained by autohydrolysis was evaluated. An empirical model was used to describe the effect of catalyst concentration (sulfuric acid, 0.1-4% w/w) and reaction time (0-60 min) based on data from a Doehlert experimental design. Catalyst concentration is the main variable influencing posthydrolysis performance, as both its linear and quadratic coefficients are statistically significant for the majority of the studied variables, namely, the ones related to sugar and byproducts production. Reaction time influences xylose and furan derivatives concentrations but not phenolics or acetic acid content. Catalyst concentration and reaction time interact synergistically, minimizing sugar recovery and promoting furan derivatives production. Based on the proposed models, it was possible to delimit an operational range that enables to obtain high monosaccharides recovery together with a slight decrease in inhibitors content as compared to the standard acid hydrolysis treatment. Furthermore, this is achieved with up to 70% less acid spending or considerable savings on reaction time. PMID:19043676

Duarte, Luís C; Silva-Fernandes, Talita; Carvalheiro, Florbela; Gírio, Francisco M

2009-05-01

222

General lysosomal hydrolysis can process prorenin accurately.  

PubMed

Renin, an aspartyl protease that catalyzes the rate-limiting step of the renin-angiotensin system, is first synthesized as an inactive precursor, prorenin. Prorenin is activated by the proteolytic removal of an amino terminal prosegment in the dense granules of the juxtaglomerular (JG) cells of the kidney by one or more proteases whose identity is uncertain but commonly referred to as the prorenin-processing enzyme (PPE). Because several extrarenal tissues secrete only prorenin, we tested the hypothesis that the unique ability of JG cells to produce active renin might be explained by the existence of a PPE whose expression is restricted to JG cells. We found that inducing renin production by the mouse kidney by up to 20-fold was not associated with the concomitant induction of candidate PPEs. Because the renin-containing granules of JG cells also contain several lysosomal hydrolases, we engineered mouse Ren1 prorenin to be targeted to the classical vesicular lysosomes of cultured HEK-293 cells, where it was accurately processed and stored. Furthermore, we found that HEK cell lysosomes hydrolyzed any artificial extensions placed on the protein and that active renin was extraordinarily resistant to proteolytic degradation. Altogether, our results demonstrate that accurate processing of prorenin is not restricted to JG cells but can occur in classical vesicular lysosomes of heterologous cells. The implication is that renin production may not require a specific PPE but rather can be achieved by general hydrolysis in the lysosome-like granules of JG cells. PMID:24965790

Xa, Lucie K; Lacombe, Marie-Josée; Mercure, Chantal; Lazure, Claude; Reudelhuber, Timothy L

2014-09-01

223

Development of low cost alkaline fuel cells  

NASA Astrophysics Data System (ADS)

Fuel cells as direct energy converters will find wide application in a future hydrogen economy. At the Institute for Hydrogen Systems (IHS) emphasis was placed on designing a mass producible, low, cost, alkaline, bipolar fuelcell. Carbon-filled plastics are used in the construction of the fuel cell stack. Teflon bonded, multi ayer carbon electrodes have been developed. The pretreatment of carbon materials proved necessary to prolong the life of the electrodes. Electrocatalysis work resulted in the replacement of the noble metal electrocatalyst of the cathode and a significant reduction in the loading of the anode. The material cost of the alkaline, bipolar hydrogen-air fuel cell currently stands at Can 250 (US 175) per kW.

Tomantschger, K.; McClusky, F.; Oporto, L.; Reid, A.; Kordesch, K.

224

Characterization of alkaline phosphatase in canine serum.  

PubMed

On the basis of carbohydrate structure, normal dog serum contains three basic types of serum alkaline phosphatase (SAP) corresponding to (1) highly branched complex (non-concanavalin A-binding), (2) complex, or (3) high-mannose (both concanavalin A-binding) oligosaccharide structures. Subsequent binding experiments with monoclonal antibody to intestinal alkaline phosphatase (AP) and bromotetramisole inhibition studies clearly indicated the presence of intestinal-like SAP. Concanavalin A (Con-A) binding characteristics suggested the presence of a bone-like SAP. Con-A-binding and isoelectric focusing results revealed the presence of two (type Ib and IIb) major SAP isoenzymes thought to be of hepatic origin. SAP isoenzymes appear to be modified when compared to tissue AP, particularly in regard to molecular size and, in some cases, carbohydrate structure. PMID:3582317

Amacher, D E; Smith, D J; Martz, L K; Hoffmann, W E

1987-01-01

225

X-Ray Structure Reveals a New Class and Provides Insight into Evolution of Alkaline Phosphatases  

PubMed Central

The alkaline phosphatase (AP) is a bi-metalloenzyme of potential applications in biotechnology and bioremediation, in which phosphate monoesters are nonspecifically hydrolysed under alkaline conditions to yield inorganic phosphate. The hydrolysis occurs through an enzyme intermediate in which the catalytic residue is phosphorylated. The reaction, which also requires a third metal ion, is proposed to proceed through a mechanism of in-line displacement involving a trigonal bipyramidal transition state. Stabilizing the transition state by bidentate hydrogen bonding has been suggested to be the reason for conservation of an arginine residue in the active site. We report here the first crystal structure of alkaline phosphatase purified from the bacterium Sphingomonas. sp. Strain BSAR-1 (SPAP). The crystal structure reveals many differences from other APs: 1) the catalytic residue is a threonine instead of serine, 2) there is no third metal ion binding pocket, and 3) the arginine residue forming bidentate hydrogen bonding is deleted in SPAP. A lysine and an aspargine residue, recruited together for the first time into the active site, bind the substrate phosphoryl group in a manner not observed before in any other AP. These and other structural features suggest that SPAP represents a new class of APs. Because of its direct contact with the substrate phosphoryl group, the lysine residue is proposed to play a significant role in catalysis. The structure is consistent with a mechanism of in-line displacement via a trigonal bipyramidal transition state. The structure provides important insights into evolutionary relationships between members of AP superfamily. PMID:21829507

Bihani, Subhash C.; Das, Amit; Nilgiriwala, Kayzad S.; Prashar, Vishal; Pirocchi, Michel; Apte, Shree Kumar; Ferrer, Jean-Luc; Hosur, Madhusoodan V.

2011-01-01

226

Alkaline electrolysers: Model and real data analysis  

Microsoft Academic Search

This paper presents an analysis of the data collected during a test of the 36 kW alkaline electrolyser at West Bacon Farm (WBF), Loughborough, UK. This data is then used to verify a software model of an electrolyser. The test consisted of collecting data under different operating conditions, in particular controlling the power supplied to the electrolyser.The experiment was divided in

Paola Artuso; Rupert Gammon; Fabio Orecchini; Simon J. Watson

2011-01-01

227

Surfactant-enhanced alkaline flooding field project  

SciTech Connect

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

French, T.R.

1991-10-01

228

Alkaline earth cation extraction from acid solution  

DOEpatents

An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

Dietz, Mark (Elmhurst, IL); Horwitz, E. Philip (Naperville, IL)

2003-01-01

229

The alkaline earth intercalates of molybdenum disulfide  

NASA Technical Reports Server (NTRS)

Molybdenum disulfide has been intercalated with calcium and strontium by means of the liquid ammonia technique. Chemical, X-ray, and superconductivity data are presented. The X-ray data reveal a lowering of crystal symmetry and increase of complexity of the structure upon intercalation with the alkaline earth metals. The Ca and Sr intercalates start to superconduct at 4 and 5.6 K, respectively, and show considerable anisotropy regarding the critical magnetic field.

Somoano, R. B.; Hadek, V.; Rembaum, A.; Samson, S.; Woollam, J. A.

1975-01-01

230

Hydrolysis of fMet-tRNA by Peptidyl Transferase  

PubMed Central

Escherichia coli and rabbit reticulocyte (f[3H]Met-tRNA·AUG·ribosome) intermediates undergo hydrolysis, with release of f[3H]methionine, upon addition of tRNA or CpCpA in the presence of acetone. This ribosomal catalyzed reaction has similar requirements, pH optimum, and antibiotic sensitivity to those of peptidyl transferase. Two antibiotics, lincomycin with E. coli ribosomes and anisomycin with reticulocyte ribosomes, inhibit peptide-bond formation and transesterification activities of peptidyl transferase, but stimulate hydrolysis of f[3H]Met-tRNA. Earlier studies have suggested peptidyl transferase activity is essential for R factor-dependent hydrolysis of f(3H)Met-tRNA. These studies indicate that peptidyl transferase has the capacity for f(3H)Met-tRNA hydrolysis and, therefore, may be responsible for peptidyl-tRNA cleavage during peptide chain termination. PMID:4943558

Caskey, C. T.; Beaudet, A. L.; Scolnick, E. M.; Rosman, M.

1971-01-01

231

Responsive behavior of regenerated cellulose in hydrolysis under microwave radiation.  

PubMed

This work studied the responsive behavior of regenerated cellulose (RC) in hydrolysis under microwave radiation. Four types of RC with different crystallinity (Cr) and degree of polymerization (DP) are produced to evaluate the reactivity of RC by step-by-step hydrolysis. Results show Cr is the key factor to affect the reactivity of RCs. With hydrolysis of amorphous region and the formation of recrystallization, the Cr of RC reaches a high value and thus weakens the reactivity. As a result, the increment of cellulose conversion and sugar yield gradually reduces. Decrease of the DP of RC is helpful to increase the speed at the onset of hydrolysis and produce high sugar yield. But, there is no direct influence with the reactivity of RC to prolong the time of pretreatment. This research provides an accurate understanding to guide the RC preparation for sugar formation with relative high efficiency under mild reaction conditions. PMID:24971946

Ni, Jinping; Na, Haining; She, Zhen; Wang, Jinggang; Xue, Wenwen; Zhu, Jin

2014-09-01

232

ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS  

EPA Science Inventory

SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external...

233

Preparation of monodisperse titania by titanium alkoxide hydrolysis  

SciTech Connect

A process for the production of monodisperse titania particles is described comprising the steps of: (a) dissolving titanium tetraalkoxide in an alcoholic medium to form a solution of the alkoxide in the alcoholic medium; (b) providing a hydrolysis solution comprising alcohol and water in amounts sufficient to hydrolyze the alkoxide in the solution; (c) adding the hydrolysis solution to the solution of the alkoxide to hydrolyze the alkoxide at hydrolysis conditions to form a dispersion of monodisperse titania particles, the hydrolysis being conducted in the presence of a component selected from the group consisting of (1) monoalkyl amines, (2) dialkyl amines, (3) trialkyl amines in combination with hydroxypropylcellulose and (4) mixtures thereof, the alkyl substituent having from 1 to 7 carbon atoms; and (d) separating and recovering the monodisperse titania particles from the dispersion.

Olson, W.L.; Liss, W.E.

1988-03-22

234

Cellulase-lignin interactions in the enzymatic hydrolysis of lignocellulose.  

E-print Network

??Lignin, a major non-carbohydrate polymer in lignocellulosic plant biomass, restricts the action of hydrolytic enzymes in the enzymatic hydrolysis of lignocellulosic feedstocks. Non-productive enzyme adsorption… (more)

Rahikainen, Jenni

2013-01-01

235

Accelerating enzymatic hydrolysis of cornstarch and cellulose using cationic polymers.  

E-print Network

??The effect of cationic polymers on the rate of hydrolysis of cornstarch and cellulosic feedstocks was investigated. Poly(diallyldimethylammonium chloride) (p-DADMAC) and cationic polyacrylamides (c-PAMs) were… (more)

Mora, Sandeep

2013-01-01

236

Kinetics of the hydrolysis of guanosine 5'-phospho-2-methylimidazolide  

NASA Technical Reports Server (NTRS)

The hydrolysis kinetics of guanosine 5'-phospho-2-methylimidazolide (2-MeImpG) in aqueous buffered solutions of various pH's was studied at 75 and 37 C, using spectrophotometric and HPLC techniques. The hydrolysis was found to be very slow even at low pH. At 75 C and pH at or below l.0, two kinetic processes were observed: the more rapid one was attributed to the hydrolysis of the phosphoimidazolide P-N bond; the second, much slower one, was attributed to the cleavage of the glycosidic bond. It is noted that the P-N hydrolysis in phosphoimidazolides is very slow compared to other phosphoramidates, and that this might be one of the reasons why the phosphoimidazolides showed an extraordinary ability to form long oligomers under template-directed conditions.

Kanavarioti, Anastassia

1986-01-01

237

A General Approach for Teaching Hydrolysis of Salts.  

ERIC Educational Resources Information Center

Presented is a general approach and equation for teaching the hydrolysis of salts. This general equation covers many more sets of conditions than those currently in textbooks. The simplifying assumptions leading to the known limiting equations are straightforward. (RH)

Aguirre-Ode, Fernando

1987-01-01

238

Mechanistic insights into the hydrolysis of organophosphorus compounds by  

E-print Network

Mechanistic insights into the hydrolysis of organophosphorus compounds by paraoxonase-1: exploring in the online version of this paper. Keywords: structure­activity relationships; paraoxonase; organophosphorus esters and organophosphorus (OP) compounds; however, its physiological role remains enigmatic

Magliery, Thomas J.

239

Energetic approach of biomass hydrolysis in supercritical water.  

PubMed

Cellulose hydrolysis can be performed in supercritical water with a high selectivity of soluble sugars. The process produces high-pressure steam that can be integrated, from an energy point of view, with the whole biomass treating process. This work investigates the integration of biomass hydrolysis reactors with commercial combined heat and power (CHP) schemes, with special attention to reactor outlet streams. The innovation developed in this work allows adequate energy integration possibilities for heating and compression by using high temperature of the flue gases and direct shaft work from the turbine. The integration of biomass hydrolysis with a CHP process allows the selective conversion of biomass into sugars with low heat requirements. Integrating these two processes, the CHP scheme yield is enhanced around 10% by injecting water in the gas turbine. Furthermore, the hydrolysis reactor can be held at 400°C and 23MPa using only the gas turbine outlet streams. PMID:25536511

Cantero, Danilo A; Vaquerizo, Luis; Mato, Fidel; Bermejo, M Dolores; Cocero, M José

2015-03-01

240

Enzymatic hydrolysis of steryl glycosides for their analysis in foods.  

PubMed

Steryl glycosides (SG) contribute significantly to the total intake of phytosterols. The standard analytical procedure involving acid hydrolysis fails to reflect the correct sterol profile of SG due to isomerization of some of the labile sterols. Therefore, various glycosylases were evaluated for their ability to hydrolyse SG under milder conditions. Using a pure SG mixture in aqueous solution, the highest glycolytic activity, as demonstrated by the decrease in SG and increase in free sterols was achieved using inulinase preparations (decrease of >95%). High glycolytic activity was also demonstrated using hemicellulase (63%). The applicability of enzymatic hydrolysis using inulinase preparations was further verified on SG extracted from foods. For example in potato peel ?(5)-avenasteryl glucoside, a labile SG, was well preserved and contributed 26.9% of the total SG. Therefore, enzymatic hydrolysis is suitable for replacing acid hydrolysis of SG in food lipid extracts to accurately determine the sterol profile of SG. PMID:24912717

Münger, Linda H; Nyström, Laura

2014-11-15

241

A SPECTROPHOTOMETRIC STUDY OF THE HYDROLYSIS OF PLUTONIUM(IV)  

Microsoft Academic Search

The hydrolysis of Pu(IV) in HâO and DâO was studied by ; means of spectrophotometric measurements at 3300 A and various acidities. The ; data were solved with the least squares method on an IBM computer (704) for the ; hydrolysis constant K = STAPuOH\\/sup 3+\\/!STAH\\/sup +\\/!\\/STAPu\\/sup 4+\\/!. ; Measurements were made at 15.4 and 25.0 deg C, and they

S. W. Rabideau; R. J. Kline

1960-01-01

242

Evaluation of abalone ?-glucuronidase substitution in current urine hydrolysis procedures.  

PubMed

This study examined the potential of abalone ?-glucuronidase as a viable and cost effective alternative to current hydrolysis procedures using acid, Helix pomatia ?-glucuronidase and Escherichia coli ?-glucuronidase. Abalone ?-glucuronidase successfully hydrolyzed oxazepam-glucuronide and lorazepam-glucuronide within 5% of the spiked control concentration. Benzodiazepines present in authentic urine specimens were within 20% of the concentrations obtained with the current hydrolysis procedure using H. pomatia ?-glucuronidase. JWH 018 N-(5-hydroxypentyl) ?-d-glucuronide was hydrolyzed within 10% of the control concentration. Authentic urine specimens showed improved glucuronide cleavage using abalone ?-glucuronidase with up to an 85% increase of drug concentration, compared with the results obtained using E. coli ?-glucuronidase. The JWH 018 and JWH 073 carboxylic acid metabolites also showed increased drug concentrations of up to 24%. Abalone ?-glucuronidase was able to completely hydrolyze a morphine-3-glucuronide control, but only 82% of total morphine was hydrolyzed in authentic urine specimens compared with acid hydrolysis results. Hydrolysis of codeine and hydromorphone varied between specimens, suggesting that abalone ?-glucuronidase may not be as efficient in hydrolyzing the glucuronide linkages in opioid compounds compared with acid hydrolysis. Abalone ?-glucuronidase demonstrates effectiveness as a low cost option for enzyme hydrolysis of benzodiazepines and synthetic cannabinoids. PMID:24488113

Malik-Wolf, Brittany; Vorce, Shawn; Holler, Justin; Bosy, Thomas

2014-04-01

243

Electron transfer precedes ATP hydrolysis during nitrogenase catalysis  

PubMed Central

The biological reduction of N2 to NH3 catalyzed by Mo-dependent nitrogenase requires at least eight rounds of a complex cycle of events associated with ATP-driven electron transfer (ET) from the Fe protein to the catalytic MoFe protein, with each ET coupled to the hydrolysis of two ATP molecules. Although steps within this cycle have been studied for decades, the nature of the coupling between ATP hydrolysis and ET, in particular the order of ET and ATP hydrolysis, has been elusive. Here, we have measured first-order rate constants for each key step in the reaction sequence, including direct measurement of the ATP hydrolysis rate constant: kATP = 70 s?1, 25 °C. Comparison of the rate constants establishes that the reaction sequence involves four sequential steps: (i) conformationally gated ET (kET = 140 s?1, 25 °C), (ii) ATP hydrolysis (kATP = 70 s?1, 25 °C), (iii) Phosphate release (kPi = 16 s?1, 25 °C), and (iv) Fe protein dissociation from the MoFe protein (kdiss = 6 s?1, 25 °C). These findings allow completion of the thermodynamic cycle undergone by the Fe protein, showing that the energy of ATP binding and protein–protein association drive ET, with subsequent ATP hydrolysis and Pi release causing dissociation of the complex between the Feox(ADP)2 protein and the reduced MoFe protein. PMID:24062462

Duval, Simon; Danyal, Karamatullah; Shaw, Sudipta; Lytle, Anna K.; Dean, Dennis R.; Hoffman, Brian M.; Antony, Edwin; Seefeldt, Lance C.

2013-01-01

244

De-ashing treatment of corn stover improves the efficiencies of enzymatic hydrolysis and consequent ethanol fermentation.  

PubMed

In this study, corn stover with different ash content was pretreated using dry dilute acid pretreatment method at high solids loading of 67% (w/w). The results indicate that the hydrolysis yield of corn stover is increased from 43.30% to 70.99%, and ethanol yield is increased from 51.74% to 73.52% when ash is removed from 9.60% to 4.98%. The pH measurement of corn stover slurry indicates that the decrease of pretreatment efficiency is due to the neutralization of sulfuric acid by alkaline compounds in the ash. The elemental analysis reveals that the ash has the similar composition with the farmland soil. This study demonstrates the importance of ash removal from lignocellulose feedstock under high solids content pretreatment. PMID:25089897

He, Yanqing; Fang, Zhenhong; Zhang, Jian; Li, Xinliang; Bao, Jie

2014-10-01

245

ATP Hydrolysis in Water -A Density Functional Study J. Akola and R. O. Jones*  

E-print Network

ATP Hydrolysis in Water - A Density Functional Study J. Akola and R. O. Jones* Institut fu¨r Festko-dependent hydrolysis reaction. Two paths for ATP hydrolysis in water with Mg2+ are studied here using the density) in the triphosphate tail of the molecule as an energy-rich bond that releases energy upon hydrolysis due

246

Theoretical Analysis of Microtubules Dynamics Using a Physical-Chemical Description of Hydrolysis  

E-print Network

Theoretical Analysis of Microtubules Dynamics Using a Physical- Chemical Description of Hydrolysis. They can be viewed as dynamic polymers that function in nonequilibrium conditions stimulated by hydrolysis-chemical description of GTP hydrolysis is presented, in which the hydrolysis rate at a given monomer depends

247

Toxicology 212 (2005) 107115 Carbofuran and malathion inhibit nucleotide hydrolysis in  

E-print Network

Toxicology 212 (2005) 107­115 Carbofuran and malathion inhibit nucleotide hydrolysis in zebrafish and ADP hydrolysis in an uncompetitive manner, but no effect was observed on AMP hydrolysis. Malathion decreased ATP and ADP hydrolysis in competitive and an uncompetitive manner, respectively, but not altered

Eizirik, Eduardo

248

Enzymatic hydrolysis of corn stalk in a hollow fiber ultrafiltration membrane reactor  

Microsoft Academic Search

A hollow fiber ultrafiltration (UF) membrane reactor was set up to investigate the enzymatic hydrolysis of steam-exploded corn stalk. It was found that the hydrolysis rate, as well as the reducing sugar (RS) yield, could be markedly enhanced in the UF membrane reactor due to the continuous removal of inhibitory products. Compared with traditional batch hydrolysis, the hydrolysis rate and

Sen Yang; Wenyong Ding; Hongzhang Chen

2009-01-01

249

Adsorption and activity profiles of cellulases during the hydrolysis of two Douglas fir pulps  

Microsoft Academic Search

The adsorption and specific activities of various cellulases were evaluated during the hydrolysis of Avicel and Douglas fir-derived kraft and refiner mechanical pulps (RMP). Both the RMP and kraft pulps required higher enzyme loadings and longer hydrolysis times to achieve complete hydrolysis than did Avicel. Complete hydrolysis of a 2% kraft pulp required an enzyme loading of 60 FPU g?1

Abdellatif Boussaid; John N. Saddler

1999-01-01

250

Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids.  

PubMed

The alkaline stability of 26 different quaternary ammonium groups (QA) is investigated for temperatures up to 160?°C and NaOH concentrations up to 10?mol?L(-1) with the aim to provide a basis for the selection of functional groups for hydroxide exchange membranes in alkaline fuel cells and of ionic-liquid cations stable in basic conditions. Most QAs exhibit unexpectedly high alkaline stability with the exception of aromatic cations. ?-Protons are found to be far less susceptible to nucleophilic attack than previously suggested, whereas the presence of benzyl groups, nearby hetero-atoms, or other electron-withdrawing species promote degradation reactions significantly. Cyclic QAs proved to be exceptionally stable, with the piperidine-based 6-azonia-spiro[5.5]undecane featuring the highest half-life at the chosen conditions. Absolute and relative stabilities presented herein stand in contrast to literature data, the differences being ascribed to solvent effects on degradation. PMID:25431246

Marino, M G; Kreuer, K D

2015-02-01

251

Beta-type calcium phosphates with and without magnesium: From hydrolysis of brushite powder to robocasting of periodic scaffolds.  

PubMed

Several approaches have attempted to replace extensive bone loss, but each of them has their limitation. Nowadays, additive manufacture techniques have shown great potential for bone engineering. The objective of this study was to synthesize beta tricalcium phosphate (?-TCP), beta tricalcium phosphate substituted by magnesium (?-TCMP), and biphasic calcium phosphate substituted by magnesium (BCMP) via hydrolysis and produce scaffolds for bone regeneration using robocasting technology. Calcium deficient apatites, with and without magnesium were obtained by hydrolysis, calcined and physico-chemically characterized. Colorimetric cell viability assay, calcium nodule formation, and the expression of alkaline phosphatase, osteocalcin, transforming growth factor beta-1 and collagen were assessed using a mouse osteoblastic cell line (MC3T3-E1). Direct-write assembly of cylindrical periodic scaffolds was done via robotic deposition using ?-TCP, ?-TCMP, and BCMP colloidal inks. The sintered scaffolds were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, Archimede's method, and uniaxial compression test. According to the cell viability assay, the powders induced cell proliferation. Calcium nodule formation and bone markers activity suggested that the materials present potential value in bone tissue engineering. The scaffolds built by robocasting presented interconnected porous and exhibited mean compressive strength between 7.63 and 18.67 MPa, compatible with trabecular bone. PMID:24277559

Richard, Raquel C; Sader, Márcia S; Dai, Jisen; Thiré, Rossana M S M; Soares, Gloria D A

2014-10-01

252

Enhanced cellulase hydrolysis of eucalyptus waste fibers from pulp mill by Tween80-assisted ferric chloride pretreatment.  

PubMed

Pretreatment combining FeCl3 and Tween80 was performed for cellulose-to-ethanol conversion of eucalyptus alkaline peroxide mechanical pulping waste fibers (EAWFs). The FeCl3 pretreatment alone showed a good effect on the enzymatic hydrolysis of EAWFs, but inhibited enzyme activity to some extent. A surfactant, Tween80, added during FeCl3 pretreatment was shown to significantly enhance enzyme reaction by eluting enzymatic inhibitors such as iron(III) that are present at the surface of the pretreated biomass. Treatment temperature, liquid-solid ratio, treatment time, FeCl3 concentration, and Tween80 dosage for pretreatment were optimized as follows: 180 °C, 8:1, 30 min, 0.15 mol/L, and 1% (w/v). Pretreated EAWFs under such optimal conditions provided enzymatic glucose (based on 100 g of oven-dried feedstock) and substrate enzymatic digestibility of EAWFs of 34.8 g and 91.3% after 72 h of enzymatic hydrolysis, respectively, with an initial cellulase loading of 20 FPU/g substrate. PMID:23480567

Chen, Liheng; Fu, Shiyu

2013-04-01

253

The Chemistry of Paper Preservation: Part 4. Alkaline Paper  

NASA Astrophysics Data System (ADS)

The inherent instability of old papers is largely due to the presence of acids which catalyze the hydrolytic degradation of cellulose. The use of alkaline paper can minimize the problem of acidity for new papers. This study focuses on the chemistry involved in the sizing of both acid and alkaline papers and the types of fillers used. The waterproofing agent that is used in acid paper is alum-precipitated rosin size, which tends to spread and create a hydrophobic surfaces over the cellulose fibers. Alkaline paper uses the synthetic sizing agents, alkyl ketene dimers(AKD) and alkyl succinic anhydrides (ASA). These alkaline sizing agents become chemically bound to the cellulose fibers with hydrophobic chains pointing outward, producing a water repellent surface. The sizing reactions take place in a neutral-to-alkaline medium. Calcium carbonate can then be used as a filler to replace expensive titanium dioxide. Finally, the advantages and potential problems in alkaline paper making are discussed.

Carter, Henry A.

1997-05-01

254

Hydrolysis of ozone pretreated energy grasses for optimal fermentable sugar production.  

PubMed

Ozonated energy grass varieties were enzymatically hydrolyzed to establish process parameters for maximum fermentable sugar production. Conditions for ozonolysis were selected on the basis of maximum delignification and glucan retention after pretreatment. To study the effect of lignin degradation products generated during ozonolysis on cellulolytic enzymes, hydrolysis was carried out for washed and unwashed pretreated solids. Washing the solids significantly (p<0.05) enhanced glucan conversion from 34.3% to 100% while delivering glucose yields of 146.2-431.9 mg/g biomass. Highest fermentable sugars were produced when grasses were ozonated for maximum delignification and washed solids were hydrolyzed using 0.1g/g Cellic® CTec2. In a comparative study on alkaline pretreatment with 1% NaOH for 60 min, Saccharum arundinaceum exhibited the highest glucan conversion with maximum sugar production of 467.9 mg/g. Although ozonolysis is an effective and environmentally friendly technique for cellulosic sugar production, process optimization is needed to ascertain economic feasibility of the process. PMID:24045197

Panneerselvam, Anushadevi; Sharma-Shivappa, Ratna R; Kolar, Praveen; Clare, Debra A; Ranney, Thomas

2013-11-01

255

Microwave-assisted hydrolysis and extraction of tricyclic antidepressants from human hair.  

PubMed

The objective of this research was to develop, optimize, and validate a modern, rapid method of preparation of human hair samples, using microwave irradiation, for analysis of eight tricyclic antidepressants (TCADs): nordoxepin, nortriptyline, imipramine, amitriptyline, doxepin, desipramine, clomipramine, and norclomipramine. It was based on simultaneous alkaline hair microwave-assisted hydrolysis and microwave-assisted extraction (MAH-MAE). Extracts were analyzed by high-performance liquid chromatography with diode-array detection (HPLC-DAD). A mixture of n-hexane and isoamyl alcohol (99:1, v/v) was used as extraction solvent and the process was performed at 60°C. Application of 1.0 mol L(-1) NaOH and microwave irradiation for 40 min were found to be optimum for hair samples. Limits of detection ranged from 0.3 to 1.2 ?g g(-1) and LOQ from 0.9 to 4.0 ?g g(-1) for the different drugs. This enabled us to quantify them in hair samples within average therapeutic concentration ranges. PMID:21127844

Wietecha-Pos?uszny, Renata; Garbacik, Aneta; Wo?niakiewicz, Micha?; Ko?cielniak, Pawe?

2011-03-01

256

Stimulation of microbial urea hydrolysis in groundwater to enhance calcite precipitation.  

PubMed

Addition of molasses and urea was tested as a means of stimulating microbial urea hydrolysis in the Eastern Snake River Plain Aquifer in Idaho. Ureolysis is an integral component of a novel remediation approach for divalent trace metal and radionuclide contaminants in groundwater and associated geomedia, where the contaminants are immobilized by coprecipitation in calcite. Generation of carbonate alkalinity from ureolysis promotes calcite precipitation. In calcite-saturated aquifers, this represents a potential long-term contaminant sequestration mechanism. In a single-well experiment, dilute molasses was injected three times over two weeks to promote overall microbial growth, followed by one urea injection. With molasses addition, total cell numbers in the groundwater increased 1-2 orders of magnitude. Estimated ureolysis rates in recovered groundwater samples increased from < 0.1 to > 25 nmol L(-1) hr(-1). A quantitative PCR assay for the bacterial ureC gene indicated that urease gene numbers increased up to 170 times above pre-injection levels. Following urea injection, calcite precipitates were recovered. Estimated values for an in situ first order ureolysis rate constant ranged from 0.016 to 0.057 d(-1). Although collateral impacts such as reduced permeability were observed, overall results indicated the viability of manipulating biogeochemical processes to promote contaminant sequestration. PMID:18497161

Fujita, Yoshiko; Taylor, Joanna L; Gresham, Tina L T; Delwiche, Mark E; Colwell, Frederick S; Mcling, Travis L; Petzke, Lynn M; Smith, Robert W

2008-04-15

257

STIMULATION OF MICROBIAL UREA HYDROLYSIS IN GROUNDWATER TO ENHANCE CALCITE PRECIPITATION  

SciTech Connect

Sequential addition of molasses and urea was tested as a means of stimulating microbial urea hydrolysis in the Eastern Snake River Plain Aquifer in Idaho. Ureolysis is an integral component of a novel remediation approach for divalent trace metal and radionuclide contaminants in groundwater and associated geomedia, where the contaminants are immobilized by coprecipitation in calcite. The generation of carbonate alkalinity from ureolysis promotes calcite precipitation. In calcite-saturated aquifers, this represents a potential long-term contaminant sequestration mechanism. In a single well experiment, dilute molasses was injected three times over two weeks to promote overall microbial growth, followed by one urea injection. With molasses addition, total cell numbers in the groundwater increased one to two orders of magnitude. Estimated ureolysis rates in recovered groundwater samples increased from <0.1 nmol L-1 hr-1 to >25 nmol L-1 hr-1. A quantitative PCR assay for the bacterial ureC gene indicated that urease gene numbers increased up to 170 times above pre-injection levels. Following urea injection, calcite precipitates were recovered. Estimated values for an in situ first order ureolysis rate constant ranged from 0.016 to 0.057 day-1. The results are promising with respect to the potential to manipulate in situ biogeochemical processes to promote contaminant sequestration.

Yoshiko Fujita; Joanna L. Taylor; Tina L. Gresham; Mark E. Delwiche; Frederick S. Colwell; Travis McLing; Lynn Petzke; Robert W. Smith

2008-04-01

258

Alkaline chemistry of transuranium elements and technetium and the treatment of alkaline radioactive wastes  

SciTech Connect

Goal of this survey is to generalize the known data on fundamental physical-chemical properties of TRUs and Tc, methods for their isolation, and to provide recommendations that will be useful for partitioning them from alkaline high-level wastes.

Delegard, C.H. [Westinghouse Hanford Co., Richland, WA (United States); Peretrukhin, V.F.; Shilov, V.P.; Pikaev, A.K. [Russian Academy of Sciences (Russian Federation). Inst. of Physical Chemistry

1995-05-01

259

Jasmonates Induce Intracellular Alkalinization and Closure of Paphiopedilum  

Microsoft Academic Search

Jasmonates (jasmonic acid or methyl jasmonate) promote stomatal closure in Paphiopedilum Supersuk (RHS, 1973) and P. tonsum (Rchb.f) Stein. Studies on guard cells loaded with pH dependent fluorescent dyes show that jasmonates cause intracellular alkalinization of up to 0-5 pH units within 5 to 15 min. Jasmonate-induced alkalinization always preceded stomatal closure and where alkalinization was not detected no closure

Guard Cells

260

Jasmonates Induce Intracellular Alkalinization and Closure of Paphiopedilum Guard Cells  

Microsoft Academic Search

Jasmonates (jasmonic acid or methyl jasmonate) promote stomatal closure inPaphiopedilum Supersuk(RHS, 1973) andP. tonsum(Rchb.f) Stein. Studies on guard cells loaded with pH dependent fluorescent dyes show that jasmonates cause intracellular alkalinization of up to 0.5 pH units within 5 to 15 min. Jasmonate-induced alkalinization always preceded stomatal closure and where alkalinization was not detected no closure occurred. Propionic acid inhibited

C. A. GEHRING; H. R. IRVING; R. McCONCHIE; R. W. PARISH

1997-01-01

261

GLOBE Videos: Hydrology Protocols - Alkalinity (9:59 min)  

NSDL National Science Digital Library

This video demonstrates students measuring the alkalinity of a water sample, using an alkalinity test kit. The resource includes a video and a written transcript, and is supported by the Alkalinity Protocol in the GLOBE Teacher's Guide. This is one of seven videos on hydrology in a 24-part instructional video series describing scientific protocols used by GLOBE (Global Learning and Observation to Benefit the Environment), a worldwide, hands-on, K-12 school-based science education program.

262

The effect of alkaline agents on retention of EOR chemicals  

SciTech Connect

This report summarizes a literature survey on how alkaline agents reduce losses of surfactants and polymers in oil recovery by chemical injection. Data are reviewed for crude sulfonates, clean anionic surfactants, nonionic surfactants, and anionic and nonionic polymers. The role of mineral chemistry is briefly described. Specific effects of various alkaline anions are discussed. Investigations needed to improve the design of alkaline-surfactant-polymer floods are suggested. 62 refs., 28 figs., 6 tabs.

Lorenz, P.B.

1991-07-01

263

Alkalinity and carbon budgets in the Mediterranean Sea  

SciTech Connect

The carbon budget of the Mediterranean Sea has never been assessed. This paper reports the results of numerous measurements of pH and alkalinity in the spring of 1991. This concentration in inorganic carbon was deduced from the measurements. The existence of simple relationships between alkalinity and salinity or inorganic carbon and salinity made it possible to assess the budget of alkalinity and carbon in the Mediterranean Sea. 55 refs., 4 figs., 4 tabs.

Copin-Montegut, C. (Universite Pierre et Marie Curie, Villefranche sur Mer (France))

1993-12-01

264

Enzymatic hydrolysis of organophosphate insecticides, a possible pesticide disposal method.  

PubMed Central

A crude cell extract from a mixed bacterial culture growing on parathion, an organophosphate insecticide, hydrolyzed parathion (21 C) at a rate of 416 nmol/min per mg of protein. This rate of enzymatic hydrolysis, when compared with chemical hydrolysis by 0.1 N sodium hydroxide at 40 C, was 2, 450 times faster. Eight of 12 commonly used organophosphate insecticides were enzymatically hydrolyzed with this enzyme preparation at rates ranging from 12 to 1,360 nmol/min per mg of protein. Seven pesticides were hydrolyzed at rates significantly higher (40 to 1,005 times faster) than chemical hydrolysis. The pH optimum for enzymatic hydrolysis of the eight pesticides ranged from 8.5 to 9.5, with less than 50% of maximal activity expressed at pH 7.0. Maximal enzyme activity occurred at 35 C. The crude extract lost its activity at the rate of only 0.75%/day when stored at 6 C. Eight organic solvents, ranging from methanol to hexane, at low concentrations stimulated enzymatic hydrolysis by 3 to 20%, whereas at higher concentrations (1,000 mg/liter) they inhibited the reaction (9 to 50%). Parathion metabolites p-nitrophenol, hydroquinone, and diethylthiophosphoric acid, at up to 100-mg/liter concentrations, did not significantly influence enzyme activity. PMID:9901

Munnecke, D M

1976-01-01

265

Starch hydrolysis modeling: application to fuel ethanol production.  

PubMed

Efficiency of the starch hydrolysis in the dry grind corn process is a determining factor for overall conversion of starch to ethanol. A model, based on a molecular approach, was developed to simulate structure and hydrolysis of starch. Starch structure was modeled based on a cluster model of amylopectin. Enzymatic hydrolysis of amylose and amylopectin was modeled using a Monte Carlo simulation method. The model included the effects of process variables such as temperature, pH, enzyme activity and enzyme dose. Pure starches from wet milled waxy and high-amylose corn hybrids and ground yellow dent corn were hydrolyzed to validate the model. Standard deviations in the model predictions for glucose concentration and DE values after saccharification were less than ± 0.15% (w/v) and ± 0.35%, respectively. Correlation coefficients for model predictions and experimental values were 0.60 and 0.91 for liquefaction and 0.84 and 0.71 for saccharification of amylose and amylopectin, respectively. Model predictions for glucose (R2 = 0.69-0.79) and DP4+ (R2 = 0.8-0.68) were more accurate than the maltotriose and maltose for hydrolysis of high-amylose and waxy corn starch. For yellow dent corn, simulation predictions for glucose were accurate (R2 > 0.73) indicating that the model can be used to predict the glucose concentrations during starch hydrolysis. PMID:21487699

Murthy, Ganti S; Johnston, David B; Rausch, Kent D; Tumbleson, M E; Singh, Vijay

2011-09-01

266

Characterization of spent AA household alkaline batteries.  

PubMed

The aim of this work is identification of the structural components of actual domestic spent alkaline AA batteries, as well as quantification of some of their characteristics. Weight, humidity, ash content, zinc and zinc oxide on anode, manganese on cathode and other metals, potassium hydroxide on the internal components and heating values for papers, anode and cathode were determined in several batteries. As expected, cathode, anode and the steel can container are the main contributors to the 23.5 g average weight of the batteries. Cathode is also the major contributor to the positive heating value of the batteries as well as to the heavy metals content. Mercury was detected in very low levels in these mercury-free batteries. Zinc and zinc oxide amounts in the anodes are highly variable. Results obtained were compared to information on alkaline batteries in the literature from 1993 to 1995; and a positive evolution in their manufacture is readily apparent. Data from the producer of batteries shows some small discrepancies relative to the results of this experimental work. PMID:15964181

Almeida, Manuel F; Xará, Susana M; Delgado, Julanda; Costa, Carlos A

2006-01-01

267

Spectroscopic characterization of alkaline earth uranyl carbonates  

NASA Astrophysics Data System (ADS)

A series of alkaline uranyl carbonates, M[UO 2(CO 3) 3]· nH 2O ( M=Mg 2, Ca 2, Sr 2, Ba 2, Na 2Ca, and CaMg) was synthesized and characterized by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) after nitric acid digestion, X-ray powder diffraction (XRD), and thermal analysis (TGA/DTA). The molecular structure of these compounds was characterized by extended X-ray absorption fine-structure (EXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). Crystalline Ba 2[UO 2(CO 3) 3]·6H 2O was obtained for the first time. The EXAFS analysis showed that this compound consists of (UO 2)(CO 3) 3 clusters similar to the other alkaline earth uranyl carbonates. The average U-Ba distance is 3.90±0.02 Å.Fluorescence wavelengths and life times were measured using time-resolved laser-induced fluorescence spectroscopy (TRLFS). The U-O bond distances determined by EXAFS, TRLFS, XPS, and Raman spectroscopy agree within the experimental uncertainties. The spectroscopic signatures observed could be useful for identifying uranyl carbonate species adsorbed on mineral surfaces.

Amayri, Samer; Reich, Tobias; Arnold, Thuro; Geipel, Gerhard; Bernhard, Gert

2005-02-01

268

The corrosion resistance of thermoset composites in alkaline environments  

SciTech Connect

Corrosion engineers need guidelines for selecting thermoset resins for aggressive applications such as hot alkali and alkaline peroxide. The suitability of fiberglass-reinforced plastic (FRP) for alkaline service depends on factors such as the ester content of the resin, the unsaturated monomer composition, and the cure system. The purpose of the present paper is to show the effect of these factors on the alkaline corrosion resistance of FRP and provide corrosion engineers with the guidance needed for selecting the best epoxy vinyl ester resins for alkaline environments.

Kelley, D.H.; Thompson, M.J. [Dow Chemical Co., Freeport, TX (United States)

1998-12-31

269

Granular starch hydrolysis for fuel ethanol production  

NASA Astrophysics Data System (ADS)

Granular starch hydrolyzing enzymes (GSHE) convert starch into fermentable sugars at low temperatures (?48°C). Use of GSHE in dry grind process can eliminate high temperature requirements during cooking and liquefaction (?90°C). In this study, GSHE was compared with two combinations of commercial alpha-amylase and glucoamylase (DG1 and DG2, respectively). All three enzyme treatments resulted in comparable ethanol concentrations (between 14.1 to 14.2% v/v at 72 hr), ethanol conversion efficiencies and ethanol and DDGS yields. Sugar profiles for the GSHE treatment were different from DG1 and DG2 treatments, especially for glucose. During simultaneous saccharification and fermentation (SSF), the highest glucose concentration for the GSHE treatment was 7% (w/v); for DG1 and DG2 treatments, maximum glucose concentration was 19% (w/v). GSHE was used in one of the fractionation technologies (enzymatic dry grind) to improve recovery of germ and pericarp fiber prior to fermentation. The enzymatic dry grind process with GSHE was compared with the conventional dry grind process using GSHE with the same process parameters of dry solids content, pH, temperature, time, enzyme and yeast usages. Ethanol concentration (at 72 hr) of the enzymatic process was 15.5% (v/v), which was 9.2% higher than the conventional process (14.2% v/v). Distillers dried grains with solubles (DDGS) generated from the enzymatic process (9.8% db) was 66% less than conventional process (28.3% db). Three additional coproducts, germ 8.0% (db), pericarp fiber 7.7% (db) and endosperm fiber 5.2% (db) were produced. Costs and amounts of GSHE used is an important factor affecting dry grind process economics. Proteases can weaken protein matrix to aid starch release and may reduce GSHE doses. Proteases also can hydrolyze protein into free amino nitrogen (FAN), which can be used as a yeast nutrient during fermentation. Two types of proteases, exoprotease and endoprotease, were studied; protease and urea addition were evaluated in the dry grind process using GSHE (GSH process). Addition of proteases resulted in higher ethanol concentrations (15.2 to 18.0% v/v) and lower (DDGS) yields (32.9 to 45.8% db) compared to the control (no protease addition). As level of proteases and GSHE increased, ethanol concentrations increased and DDGS yields decreased. Proteases addition reduced required GSHE dose. Ethanol concentrations with protease addition alone were higher than with urea or with addition of both protease and urea. Corn endosperm consists of soft and hard endosperm. More exposed starch granules and rough surfaces produced from soft endosperm compared to hard endosperm will create more surface area which will benefit the solid phase hydrolysis as used in GSH process. In this study, the effects of protease, urea, endosperm hardness and GSHE levels on the GSH process were evaluated. Soft and hard endosperm materials were obtained by grinding and sifting flaking grits from dry milling pilot plant. Soft endosperm resulted in higher ethanol concentrations (at 72 hr) compared to ground corn or hard endosperm. Addition of urea increased ethanol concentrations (at 72 hr) for soft and hard endosperm. The effect of protease addition on increasing ethanol concentrations and fermentation rates was more predominant for soft endosperm, less for hard endosperm and least for ground corn. The GSH process with protease resulted in higher ethanol concentration than that with urea. For fermentation of soft endosperm, GSHE dose can be reduced. Ground corn fermented faster at the beginning than hard and soft endosperm due to the presence of inherent nutrients which enhanced yeast growth.

Wang, Ping

270

Hydrolysis of polycarbonate catalyzed by ionic liquid [Bmim][Ac].  

PubMed

Hydrolysis of polycarbonate (PC) was studied using ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]) as a catalyst. The influences of temperature, time, water dosage and [Bmim][Ac] dosage on the hydrolysis reaction were examined. Under the conditions of temperature 140°C, reaction time 3.0 h, m([Bmim][Ac]):m(PC)=1.5:1 and m(H(2)O):m(PC)=0.35:1, the conversion of PC was nearly 100% and the yield of bisphenol A (BPA) was over 96%. The ionic liquid could be reused up to 6 times without apparent decrease in the conversion of PC and yield of BPA. The kinetics of the reaction was also investigated. The results showed that the hydrolysis of PC in [Bmim][Ac] was a first-order kinetic reaction with an activation energy of 228 kJ/mol. PMID:23246956

Song, Xiuyan; Liu, Fusheng; Li, Lei; Yang, Xuequn; Yu, Shitao; Ge, Xiaoping

2013-01-15

271

Monoolein production by triglycerides hydrolysis using immobilized Rhizopus oryzae lipase.  

PubMed

Lipase extracted from Rhizopus oryzae was immobilized in alginate gel beads. The effects of the immobilization conditions, such as, alginate concentration, CaCl2 concentration and amount of initial enzyme on retained activity (specific activity ratio of entrapped active lipase to free lipase) were investigated. The optimal conditions for lipase entrapment were determined: 2% (w/v) alginate concentration, 100mM CaCl2 and enzyme ratio of 2000IU/mL.In such conditions, immobilized lipase by inclusion in alginate showed a highest stability and activity, on olive oil hydrolysis reaction where it could be reused for 10 cycles. After 15min of hydrolysis reaction, the mass composition of monoolein, diolein and triolein were about 78%, 10% and 12%. Hydrolysis' products purification by column chromatography lead to a successful separation of reaction compounds and provide a pure fraction of monoolein which is considered as the widest used emulsifier in food and pharmaceutical industries. PMID:24755261

Ghattas, Nesrine; Abidi, Ferid; Galai, Said; Marzouki, M Nejib; Salah, Abderraouf Ben

2014-07-01

272

Soluble epoxide hydrolase regulates hydrolysis of vasoactive epoxyeicosatrienoic acids.  

PubMed

The cytochrome P450-derived epoxyeicosatrienoic acids (EETs) have potent effects on renal vascular reactivity and tubular sodium and water transport; however, the role of these eicosanoids in the pathogenesis of hypertension is controversial. The current study examined the hydrolysis of the EETs to the corresponding dihydroxyeicosatrienoic acids (DHETs) as a mechanism for regulation of EET activity and blood pressure. EET hydrolysis was increased 5- to 54-fold in renal cortical S9 fractions from the spontaneously hypertensive rat (SHR) relative to the normotensive Wistar-Kyoto (WKY) rat. This increase was most significant for the 14,15-EET regioisomer, and there was a clear preference for hydrolysis of 14, 15-EET over the 8,9- and 11,12-EETs. Increased EET hydrolysis was consistent with increased expression of soluble epoxide hydrolase (sEH) in the SHR renal microsomes and cytosol relative to the WKY samples. The urinary excretion of 14,15-DHET was 2.6-fold higher in the SHR than in the WKY rat, confirming increased EET hydrolysis in the SHR in vivo. Blood pressure was decreased 22+/-4 mm Hg (P:<0.01) 6 hours after treatment of SHRs with the selective sEH inhibitor N:, N:'-dicyclohexylurea; this treatment had no effect on blood pressure in the WKY rat. These studies identify sEH as a novel therapeutic target for control of blood pressure. The identification of a potent and selective inhibitor of EET hydrolysis will be invaluable in separating the vascular effects of the EET and DHET eicosanoids. PMID:11090543

Yu, Z; Xu, F; Huse, L M; Morisseau, C; Draper, A J; Newman, J W; Parker, C; Graham, L; Engler, M M; Hammock, B D; Zeldin, D C; Kroetz, D L

2000-11-24

273

A kinetic study on sesame cake protein hydrolysis by Alcalase.  

PubMed

In the present study, the hydrolysis of sesame cake protein was performed by Alcalase, a bacterial protease produced by Bacillus licheniformis, to investigate the reaction kinetics of sesame cake hydrolysis and to determine decay and product inhibition effects for Alcalase. The reactions were carried out for 10 min in 0.1 L of aqueous solutions containing 10, 15, 20, 25, and 30 g protein/L at various temperature and pH values. To determine decay and product inhibition effects for Alcalase, a series of inhibition experiments were conducted with the addition of various amounts of hydrolysate. The reaction kinetics was investigated by initial rate approach. The initial reaction rates were determined from the slopes of the linear models that fitted to the experimental data. The kinetic parameters, K(m) and V(max), were estimated as 41.17 g/L and 9.24 meqv/L x min. The Lineweaver-Burk plots showed that the type of inhibition for Alcalase determined as uncompetitive, and the inhibition constant, K(i), was estimated as 38.24% (hydrolysate/substrate mixture). Practical Application: Plant proteins are increasingly being used as an alternative to proteins from animal sources to perform functional roles in food formulation. Knowledge of the kinetics of the hydrolysis reaction is essential for the optimization of enzymatic protein hydrolysis and for increasing the utilization of plant proteins in food products. Therefore, in the present study, the hydrolysis of sesame cake protein was performed by Alcalase, a bacterial protease produced by B. licheniformis, to investigate the reaction kinetics of sesame cake hydrolysis and to determine decay and product inhibition effects for Alcalase. PMID:21535655

Demirhan, Elçin; Apar, Dilek K?l?ç; Özbek, Belma

2011-01-01

274

The Mechanisms of Plant Cell Wall Deconstruction during Enzymatic Hydrolysis  

PubMed Central

Mechanical agitation during enzymatic hydrolysis of insoluble plant biomass at high dry matter contents is indispensable for the initial liquefaction step in biorefining. It is known that particle size reduction is an important part of liquefaction, but the mechanisms involved are poorly understood. Here we put forward a simple model based on mechanical principles capable of capturing the result of the interaction between mechanical forces and cell wall weakening via hydrolysis of glucosidic bonds. This study illustrates that basic material science insights are relevant also within biochemistry, particularly when it comes to up-scaling of processes based on insoluble feed stocks. PMID:25232741

Thygesen, Lisbeth G.; Thybring, Emil E.; Johansen, Katja S.; Felby, Claus

2014-01-01

275

Hydrolysis of xylan by an immobilized xylanase from Aureobasidium pullanans  

SciTech Connect

The beta-(1,4)-linked xylose residues that comprise the backbone of the abundant plant polymer xylan can be released by enzymic hydrolysis. Xylanase, which is produced in exceptionally high levels by the color-variant strain of A. pullulans, was immobilized onto a macroporous ceramic carrier. Despite a low coupling efficiency, it was possible to run the reactor under a wide range of conditions with flow rates of 3-10 bed volumes/minute of 1% soluble xylan with no detectable leaching of enzyme. The size distribution of products and rate of xylan hydrolysis were very similar for the immobilized and soluble enzymes. (Refs. 13).

Allenza, P.; Scherl, D.S.; Detroy, R.W.; Leathers, T.D.; Scott, C.D. (ed.)

1986-01-01

276

Hydrolysis of xylan by an immobilized xylanase from Aureobasidium pullulans  

SciTech Connect

The beta-(1,4)-linked xylose residues that comprise the backbone of the abundant plant polymer xylan can be released by enzymic hydrolysis. Xylanase, which is produced in exceptionally high levels by the color-variant strain Y-2311-1 of A. pullulans, was immobilized onto a macroporous ceramic carrier. Despite a low coupling efficiency, it was possible to run the reactor under a wide range of conditions with flow rates of 3-10 bed volumes/minute of 1% soluble xylan with no detectable leaching of enzyme. The size distribution of products and rate of xylan hydrolysis were very similar for the immobilized and soluble enzymes. (Refs. 13).

Allenza, P.; Scherl, D.S.; Detroy, R.W.; Leathers, T.D.; Scott, C.D. (ed.).

1986-01-01

277

Microwave-assisted hydrolysis of polysaccharides over polyoxometalate clusters.  

PubMed

Polyoxometalate (POM) clusters were utilized as recyclable acid catalysts and microwave-absorbing agents for the microwave-assisted hydrolysis of corn starch and crystalline cellulose. Phosphotungstic (PW) and silicotungstic (SiW) acids showed high hydrolyzing activity, while phosphomolybdic acid (PMo) showed lower glucose stability. The PW catalyst could be recycled by ether extraction at least 4 times without changing its catalytic activity. The addition of PW could reduce the energy demand required for running the hydrolysis by 17-23%. The dielectric property of the aqueous PW solution was important for increasing the microwave-absorption capability of the reaction system and reducing the energy consumption. PMID:23859983

Tsubaki, Shuntaro; Oono, Kiriyo; Ueda, Tadaharu; Onda, Ayumu; Yanagisawa, Kazumichi; Mitani, Tomohiko; Azuma, Jun-ichi

2013-09-01

278

Benzene/nitrous oxide flammability in the precipitate hydrolysis process  

SciTech Connect

The HAN (hydroxylamine nitrate) process for destruction of nitrite in precipitate hydrolysis produces nitrous oxide (N2O) gas as one of the products. N2O can form flammable mixtures with benzene which is also present due to radiolysis and hydrolysis of tetraphenylborate. Extensive flame modeling and explosion testing was undertaken to define the minimum oxidant for combustion of N2O/benzene using both nitrogen and carbon dioxide as diluents. The attached memorandum interprets and documents the results of the studies.

Jacobs, R A [Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Lab.

1989-09-18

279

Mutation of a single amino acid converts germ cell alkaline phosphatase to placental alkaline phosphatase.  

PubMed

Human placental and germ cell alkaline phosphatases (PLAP and GCAP, respectively), are characterized by their differential sensitivities to inhibition by L-leucine, EDTA, and heat. Yet, they differ by only 7 amino acids at positions 15, 67, 68, 84, 241, 254, and 429 within their respective 484 residues. To determine the structural basis and the amino acid(s) involved in these physicochemical differences, we constructed three GCAP mutants by site-directed mutagenesis and six GCAP/PLAP chimeras and then expressed these alkaline phosphatase mutants in COS-1 cells. We report that the differential reactivity of PLAP and GCAP depends critically on a single amino acid at position 429. GCAP with Gly-429 is strongly inhibited by L-leucine, EDTA, and heat, whereas PLAP with Glu-429 is resistant. By substituting Gly-429 of GCAP with a series of amino acids, we demonstrate that the relative sensitivities of these mutants to L-leucine, EDTA, and heat inhibition are, in general, parallel. Mutants in the order of resistance to these treatments are: Glu (most resistant), Asp/Ile/Leu, Gln/Val/Lys, Ser/His, and Arg/Thr/Met/Cys/Phe/Trp/Tyr/Pro/Asn/Ala/Gly (least resistant). However, the Ser-429 and His-429 mutants were more resistant to EDTA and heat inhibition than the wild-type GCAP, but were equally sensitive to L-leucine inhibition. Structural analysis of mammalian alkaline phosphatase modeled on the refined crystal structure of Escherichia coli alkaline phosphatase indicates that the negative charge of Glu-429 of PLAP, which simultaneously stabilizes the protein as a whole and the metal binding specifically, probably acts through interactions with the metal ligand His-320 (His-331 in E. coli alkaline phosphatase). Replacement of codon 429 with Gly in GCAP leads to destabilization and loosening of the metal binding. The data suggest that the natural binding site for L-leucine may be near position 429, with the amino and carboxyl groups of L-leucine interacting with bound phosphate and His-432 (His-412 in E. coli alkaline phosphatase), respectively. PMID:1939159

Watanabe, T; Wada, N; Kim, E E; Wyckoff, H W; Chou, J Y

1991-11-01

280

Purification and characterization of a serine alkaline protease from Bacillus clausii GMBAE 42.  

PubMed

An extracellular serine alkaline protease of Bacillus clausii GMBAE 42 was produced in protein-rich medium in shake-flask cultures for 3 days at pH 10.5 and 37 degrees C. Highest alkaline protease activity was observed in the late stationary phase of cell cultivation. The enzyme was purified 16-fold from culture filtrate by DEAE-cellulose chromatography followed by (NH(4))(2)SO(4) precipitation, with a yield of 58%. SDS-PAGE analysis revealed the molecular weight of the enzyme to be 26.50 kDa. The optimum temperature for enzyme activity was 60 degrees C; however, it is shifted to 70 degrees C after addition of 5 mM Ca(2+) ions. The enzyme was stable between 30 and 40 degrees C for 2 h at pH 10.5; only 14% activity loss was observed at 50 degrees C. The optimal pH of the enzyme was 11.3. The enzyme was also stable in the pH 9.0--12.2 range for 24 h at 30 degrees C; however, activity losses of 38% and 76% were observed at pH values of 12.7 and 13.0, respectively. The activation energy of Hammarsten casein hydrolysis by the purified enzyme was 10.59 kcal mol(-1) (44.30 kJ mol(-1)). The enzyme was stable in the presence of the 1% (w/v) Tween-20, Tween-40,Tween-60, Tween-80, and 0.2% (w/v) SDS for 1 h at 30 degrees C and pH 10.5. Only 10% activity loss was observed with 1% sodium perborate under the same conditions. The enzyme was not inhibited by iodoacetate, ethylacetimidate, phenylglyoxal, iodoacetimidate, n-ethylmaleimidate, n-bromosuccinimide, diethylpyrocarbonate or n-ethyl-5-phenyl-iso-xazolium-3'-sulfonate. Its complete inhibition by phenylmethanesulfonylfluoride and relatively high k (cat) value for N-Suc-Ala-Ala-Pro-Phe-pNA hydrolysis indicates that the enzyme is a chymotrypsin-like serine protease. K (m) and k (cat) values were estimated at 0.655 microM N-Suc-Ala-Ala-Pro-Phe-pNA and 4.21 x 10(3) min(-1), respectively. PMID:15988584

Kazan, Dilek; Denizci, Aziz Akin; Oner, Mine N Kerimak; Erarslan, Altan

2005-08-01

281

Oxygen electrodes for rechargeable alkaline fuel cells  

NASA Technical Reports Server (NTRS)

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

Swette, Larry; Giner, Jose

1987-01-01

282

Polyvinyl alcohol membranes as alkaline battery separators  

NASA Technical Reports Server (NTRS)

Polyvinly alcohol (PVA) cross-linked with aldehyde reagents yields membranes that demonstrate properties that make them suitable for use as alkaline battery separators. Film properties can be controlled by the choice of cross-linker, cross-link density and the method of cross-linking. Three methods of cross-linking and their effects on film properties are discussed. Film properties can also be modified by using a copolymer of vinyl alcohol and acrylic acid as the base for the separator and cross-linking it similarly to the PVA. Fillers can be incorporated into the films to further modify film properties. Results of separator screening tests and cell tests for several variations of PBA films are discussed.

Sheibley, D. W.; Gonzalez-Sanabria, O.; Manzo, M. A.

1982-01-01

283

GEOCHEMISTRY: The Importance of Being Alkaline  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. The earliest forms of "protolife" on Earth must have been able to reproduce and replicate; it is likely that they were also cellular. How might such systems have formed? In his Perspective, Russell highlights the report by Hanczyc et al., who show that clay particles can catalyze the formation of lipid vesicles. These particles also adsorb RNA. If the vesicles are forced to divide, RNA is distributed among the daughter vesicles. Similar conditions to those used in the experiments may have existed at mounds created by alkaline, hydrothermal seepages on the ancient ocean floor. However, instead of lipids, polypeptides formed from amino acids may have formed the first organic membranes.

Michael John Russell (Scottish Universities Environmental Research Centre;)

2003-10-24

284

Polyvinyl alcohol membranes as alkaline battery separators  

SciTech Connect

Polyvinyl alcohol (PVA) cross-linked with aldehyde reagents yields membranes that demonstrate properties that make them suitable for use as alkaline battery separators. Film properties can be controlled by the choice of cross-linker, cross-link density and the method of cross-linking. Three methods of cross-linking and their effects on film properties are discussed. Film properties can also be modified by using a copolymer of vinyl alcohol and acrylic acid as the base for the separator and cross-linking it similarly to the PVA. Fillers can be incorporated into the films to further modify film properties. Results of separator screening tests and cell tests for several variations of PBA films are discussed.

Sheibley, D.W.; Gonzalez-Sanabria, O.; Manzo, M.

1982-01-01

285

The Nickel(111)/Alkaline Electrolyte Interface  

NASA Technical Reports Server (NTRS)

The electrochemical properties of Ni (111) prepared and characterized in ultra high vacuum, UHV, by surface analytical techniques have been examined in alkaline media by cyclic voltammetry using an UHV-electrochemical cell transfer system designed and built in this laboratory. Prior to the transfer, the Ni(111) surfaces were exposed to saturation coverages of CO in UHV in an attempt to protect the surface from possible contamination with other gases during the transfer. Temperature Programmed Desorption, TPD, of CO-dosed Ni (111) surfaces displaying sharp c(4x2), LEED patterns, subsequently exposed to water-saturated Ar at atmospheric pressure in an auxiliary UHV compatible chamber and finally transferred back to the main UHV chamber, yielded CO2 and water as the only detectable products. This indicates that the CO-dosed surfaces react with water and/or bicarbonate and hydroxide as the most likely products. Based on the integration of the TPD peaks, the combined amounts of H2O and CO2 were found to be on the order of a single monolayer. The reacted c(4x2)CO/Ni(111) layer seems to protect the surface from undergoing spontaneous oxidation in strongly alkaline solutions. This was evidenced by the fact that the open circuit potential observed immediately after contact with deaerated 0.1 M KOH was about 0.38 V vs. DHE, drifting slightly towards more negative values prior to initiating the voltametric scans. The average ratio of the integrated charge obtained in the first positive linear scan in the range of 0.35 to 1.5 V vs. DHE (initiated at the open circuit potential) and the first (and subsequent) linear negative scans in the same solution yielded for various independent runs a value of 3.5 +/- 0.3. Coulometric analysis of the cyclic voltammetry curves indicate that the electrochemically formed oxyhydroxide layer involves a charge equivalent to 3.2 +/- 0.4 layers of Ni metal.

Wang, Kuilong; Chottiner, G. S.; Scherson, D. A.; Reid, Margaret A.

1991-01-01

286

The Chemistry of Paper Preservation: Part 4. Alkaline Paper  

Microsoft Academic Search

The inherent instability of old papers is largely due to the presence of acids which catalyze the hydrolytic degradation of cellulose. The use of alkaline paper can minimize the problem of acidity for new papers. This study focuses on the chemistry involved in the sizing of both acid and alkaline papers and the types of fillers used. The waterproofing agent

Henry A. Carter

1997-01-01

287

Increased river alkalinization in the Eastern U.S  

NASA Astrophysics Data System (ADS)

The interaction between human activities and watershed geology is accelerating long-term changes in the carbon cycle of rivers. We evaluated changes in bicarbonate alkalinity, a product of chemical weathering, and tested for long-term trends at 97 sites in the eastern United States draining over 260,000 km2. We observed statistically significant increasing trends in alkalinity at 62 of the 97 sites, while remaining sites exhibited no significant decreasing trends. Over 50% of study sites also had statistically significant increasing trends in concentrations of calcium (another product of chemical weathering) where data were available. River alkalinization rates were significantly related to watershed carbonate lithology, acid deposition, and topography. These 3 variables explained ~40% of variation in river alkalinization rates. The strongest predictor of river alkalinization rates was carbonate lithology. The most rapid rates of river alkalinization occurred at sites with highest inputs of acid deposition and highest elevation. The rise of alkalinity in many rivers throughout the eastern U.S. suggests human-accelerated chemical weathering, in addition to previously documented impacts of mining and land use. Increased river alkalinization has major environmental implications including impacts on water hardness and salinization of drinking water, alterations of air-water exchange of CO2, coastal ocean acidification, and the influence of bicarbonate availability on primary production.

Kaushal, S.; Likens, G. E.; Utz, R.; Pace, M.; Grese, M.; Yepsen, M.

2013-12-01

288

Space-time variability of alkalinity in the Mediterranean Sea  

NASA Astrophysics Data System (ADS)

The paper provides a basin assessment of the spatial distribution of ocean alkalinity in the Mediterranean Sea. The assessment is made using a 3-D transport-biogeochemical-carbonate model to integrate the available experimental findings, which also constrains model output. The results indicate that the Mediterranean Sea shows alkalinity values that are much higher than those observed in the Atlantic Ocean on a basin-wide scale. A marked west-to-east surface gradient of alkalinity is reproduced as a response to the terrestrial discharges, the mixing effect with the Atlantic water entering from the Gibraltar Strait and the Black Sea water from Dardanelles, and the surface flux of evaporation minus precipitation. Dense water production in marginal seas (Adriatic and Aegean Seas), where alkaline inputs are relevant, and the Mediterranean thermohaline circulation sustains the west-to-east gradient along the entire water column. In the surface layers, alkalinity has a relevant seasonal cycle (up to 40 ?mol kg-1) that is driven both by physical and biological processes. A comparison of alkalinity vs. salinity indicates that different regions present different relationships. In regions of freshwater influence, the two measures are negatively correlated due to riverine alkalinity input, whereas they are positively correlated in open seas. Alkalinity always is much higher than in the Atlantic waters, which might indicate a higher than usual buffering capacity towards ocean acidification, even at high concentrations of dissolved inorganic carbon.

Cossarini, G.; Lazzari, P.; Solidoro, C.

2014-09-01

289

Distribution of alkaline phosphatase in serum protein fractions  

Microsoft Academic Search

A technique for measuring the alkaline phosphatase activity of serum protein fractions separated by electrophoresis on cellulose acetate strips is described.Alkaline phosphatase activity in alpha 2, alpha 1, and beta globulins and in albumin is present in varying proportions in normal and pathological sera. In normal sera peak activity is in the alpha 2 globulins and beta globulins have a

N. H. Korner

1962-01-01

290

Alkaline Membrane Fuel Cell System Break-Out Session  

E-print Network

on anode + Alkaline membrane on cathode ­ High temperature operation ­ KOH to capture carbonate · SystemAlkaline Membrane Fuel Cell Workshop System Break-Out Session Anil Trehan (CommScope) Huyen Dinh/stop cycles · Ordinary air operation at ambient temperature (CO2 scrubber part of system) #12;Medium Term Fuel

291

Surfactant-Enhanced Low-pH Alkaline Flooding  

Microsoft Academic Search

This paper reports sodium bicarbonate investigated as a potential alkaline agent in surfactant-enhanced alkaline flooding because it has very little tendency to dissolve silicate minerals. In experiments performed with Wilmington, CA, crude oil and three types of surfactants, the bicarbonate\\/surfactant combination caused a marked lowering of interfacial tension (IFT). Bicarbonate protected the surfactant against divalent cations and reduced adsorption of

Deborah Peru; Philip Lorenz

1990-01-01

292

Alkalinity distribution in the western North Atlantic Ocean margins  

Microsoft Academic Search

Total alkalinity (TA) distribution and its relationship with salinity (S) along the western North Atlantic Ocean (wNAO) margins from the Labrador Sea to tropical areas are examined in this study. Based on the observed TA-S patterns, the mixing processes that control alkalinity distribution in these areas can be categorized into a spectrum of patterns that are bracketed by two extreme

Wei-Jun Cai; Xinping Hu; Wei-Jen Huang; Li-Qing Jiang; Yongchen Wang; Tsung-Hung Peng; Xin Zhang

2010-01-01

293

Dynamic Properties of the Alkaline Vesicle Population at Hippocampal Synapses  

PubMed Central

In compensatory endocytosis, scission of vesicles from the plasma membrane to the cytoplasm is a prerequisite for intravesicular reacidification and accumulation of neurotransmitter molecules. Here, we provide time-resolved measurements of the dynamics of the alkaline vesicle population which appears upon endocytic retrieval. Using fast perfusion pH-cycling in live-cell microscopy, synapto-pHluorin expressing rat hippocampal neurons were electrically stimulated. We found that the relative size of the alkaline vesicle population depended significantly on the electrical stimulus size: With increasing number of action potentials the relative size of the alkaline vesicle population expanded. In contrast to that, increasing the stimulus frequency reduced the relative size of the population of alkaline vesicles. Measurement of the time constant for reacification and calculation of the time constant for endocytosis revealed that both time constants were variable with regard to the stimulus condition. Furthermore, we show that the dynamics of the alkaline vesicle population can be predicted by a simple mathematical model. In conclusion, here a novel methodical approach to analyze dynamic properties of alkaline vesicles is presented and validated as a convenient method for the detection of intracellular events. Using this method we show that the population of alkaline vesicles is highly dynamic and depends both on stimulus strength and frequency. Our results implicate that determination of the alkaline vesicle population size may provide new insights into the kinetics of endocytic retrieval. PMID:25079223

Röther, Mareike; Brauner, Jan M.; Ebert, Katrin; Welzel, Oliver; Jung, Jasmin; Bauereiss, Anna; Kornhuber, Johannes; Groemer, Teja W.

2014-01-01

294

Increased river alkalinization in the Eastern U.S.  

PubMed

The interaction between human activities and watershed geology is accelerating long-term changes in the carbon cycle of rivers. We evaluated changes in bicarbonate alkalinity, a product of chemical weathering, and tested for long-term trends at 97 sites in the eastern United States draining over 260,000 km(2). We observed statistically significant increasing trends in alkalinity at 62 of the 97 sites, while remaining sites exhibited no significant decreasing trends. Over 50% of study sites also had statistically significant increasing trends in concentrations of calcium (another product of chemical weathering) where data were available. River alkalinization rates were significantly related to watershed carbonate lithology, acid deposition, and topography. These three variables explained ~40% of variation in river alkalinization rates. The strongest predictor of river alkalinization rates was carbonate lithology. The most rapid rates of river alkalinization occurred at sites with highest inputs of acid deposition and highest elevation. The rise of alkalinity in many rivers throughout the Eastern U.S. suggests human-accelerated chemical weathering, in addition to previously documented impacts of mining and land use. Increased river alkalinization has major environmental implications including impacts on water hardness and salinization of drinking water, alterations of air-water exchange of CO2, coastal ocean acidification, and the influence of bicarbonate availability on primary production. PMID:23883395

Kaushal, Sujay S; Likens, Gene E; Utz, Ryan M; Pace, Michael L; Grese, Melissa; Yepsen, Metthea

2013-09-17

295

ChemTeacher: Alkaline Earth Metals = Group 2 (IIA)  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Alkaline Earth Metals page includes resources for teaching students about the discovery, properties, and uses of the alkaline earth metals.

2011-01-01

296

The Chemistry of Paper Preservation Part 4. Alkaline Paper.  

ERIC Educational Resources Information Center

Discusses the problem of the inherent instability of paper due to the presence of acids that catalyze the hydrolytic degradation of cellulose. Focuses on the chemistry involved in the sizing of both acid and alkaline papers and the types of fillers used. Discusses advantages and problems of alkaline papermaking. Contains 48 references. (JRH)

Carter, Henry A.

1997-01-01

297

Magnetite solubility and phase stability in alkaline media at elevated temperatures  

SciTech Connect

Magnetite, Fe{sub 3}O{sub 4}, is the dominant oxide constituent of the indigenous corrosion layers that form on iron base alloys in high purity, high temperature water. The apparent simultaneous stability of two distinct oxidation states of iron in this metal oxide is responsible for its unique solubility behavior. The present work was undertaken to extend the experimental and theoretical bases for estimating solubilities of an iron corrosion product (Fe{sub 3}O{sub 4}/Fe(OH){sub 2}) over a broader temperature range and in the presence of complexing, pH-controlling reagents. These results indicate that a surface layer of ferrous hydroxide controls magnetite solubility behavior at low temperatures in much the same manner as a surface layer of nickel(II) hydroxide was previously reported to control the low temperature solubility behavior of NiO. The importance of Fe(III) ion complexes implies not only that most previously-derived thermodynamic properties of the Fe(OH){sub 3}{sup {minus}} ion are incorrect, but that magnetite phase stability probably shifts to favor a sodium ferric hydroxyphosphate compound in alkaline sodium phosphate solutions at elevated temperatures. The test methodology involved pumping alkaline solutions of known composition through a bed of Fe{sub 3}O{sub 4} granules and analyzing the emerging solution for Fe. Two pH-controlling reagents were tested: sodium phosphate and ammonia. Equilibria for the following reactions were described in thermodynamic terms: (a) Fe(OH){sub 2}/Fe{sub 3}O{sub 4} dissolution and transformation, (b) Fe(II) and Fe(III) ion hydroxocomplex formation (hydrolysis), (c) Fe(II) ion amminocomplex formation, and (d) Fe(II) and Fe(III) ion phosphatocomplex formation. 36 refs.

Ziemniak, S.E.; Jones, M.E.; Combs, K.E.S.

1994-05-01

298

Heterologous expression and functional characterization of a plant alkaline phytase in Pichia pastoris.  

PubMed

Phytases catalyze the sequential hydrolysis of phytic acid (myo-insositol hexakisphosphate), the most abundant inositol phosphate in cells. Phytic acid constitutes 3-5% of the dry weight of cereal grains and legumes such as corn and soybean. The high concentration of phytates in animal feed and the inability of non-ruminant animals such as swine and poultry to digest phytates leads to phosphate contamination of soil and water bodies. The supplementation of animal feed with phytases results in increased bioavailability to animals and decreased environmental contamination. Therefore, phytases are of great commercial importance. Phytases with a range of properties are needed to address the specific digestive needs of different animals. Alkaline phytase (LlALP1 and LlALP2) which possess unique catalytic properties that have the potential to be useful as feed and food supplement has been identified in lily pollen. Substantial quantities of alkaline phytase are needed for animal feed studies. In this paper, we report the heterologous expression of LlALP2 from lily pollen in Pichia pastoris. The expression of recombinant LlALP2 (rLlALP2) was optimized by varying the cDNA coding for LlALP2, host strain and growth conditions. The catalytic properties of recombinant LlALP2 were investigated extensively (substrate specificity, pH- and temperature dependence, and the effect of Ca(2+), EDTA and inhibitors) and found to be very similar to that of the native LlALP2 indicating that rLlALP2 from P. pastoris can serve as a potential source for structural and animal feed studies. PMID:20655385

Johnson, Steven C; Yang, Mimi; Murthy, Pushpalatha P N

2010-12-01

299

Salt- and alkaline-tolerance are linked in Acacia.  

PubMed

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

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

2014-07-01

300

Single Molecule Study of Cellulase Hydrolysis of Crystalline Cellulose  

SciTech Connect

This report seeks to elucidate the role of cellobiohydrolase-I (CBH I) in the hydrolysis of crystalline cellulose. A single-molecule approach uses various imaging techniques to investigate the surface structure of crystalline cellulose and changes made in the structure by CBH I.

Liu, Y.-S.; Luo, Y.; Baker, J. O.; Zeng, Y.; Himmel, M. E.; Smith, S.; Ding, S.-Y.

2009-12-01

301

Effect of particle size on enzymatic hydrolysis of pretreated Miscanthus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Particle size reduction is a crucial factor in transportation logistics as well as cellulosic conversion. The effect of particle size on enzymatic hydrolysis of pretreated Miscanthus x giganteus was determined. Miscanthus was ground using a hammer mill equipped with screens having 0.08, 2.0 or 6.0...

302

ENZYMATIC HYDROLYSIS OF CLOVER-GRASS MIXTURES FOR ETHANOL  

E-print Network

ENZYMATIC HYDROLYSIS OF CLOVER- GRASS MIXTURES FOR ETHANOL PRODUCTION MARTÍN, C.1,2 , THOMSEN, M. H, Risø National Laboratory, P.O.Box 49, DK-4000 Roskilde, Denmark Clover (Trifolium repens L.)-grass.g. organic farming systems. Since clover and grass are rich in carbohydrates, mainly cellulose

303

Penicillin Hydrolysis: A Kinetic Study of a Multistep, Multiproduct Reaction.  

ERIC Educational Resources Information Center

Background, procedures used, and typical results are provided for an experiment in which students carry out the necessary measurements on the acid-catalysis of penicillin in two hours. By applying kinetic theory to the data obtained, the reaction pathways for the hydrolysis of potassium benzyl penicillin are elucidated. (JN)

McCarrick, Thomas A.; McLafferty, Fred W.

1984-01-01

304

ACID AND ENZYMATIC HYDROLYSIS OF SALINE BIOMASS FOR SUGAR PRODUCTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Saline crops were evaluated for their potential to be used as feedstock for fermentable sugar production via dilute acid pretreatment and enzymatic hydrolysis. The saline crops included two woods, Athel (Tamarix aphylla L) and Eucalyptus (Eucalyptus camaldulensis), and two grasses, Jose Tall Wheatgr...

305

REVISED TREATMENT OF N2 O5 HYDROLYSIS IN CMAQ  

EPA Science Inventory

In this presentation, revised treatment of homogeneous and heterogeneous hydrolysis of dinitrogen pentoxide in the Community Multiscale Air Quality model version 4.6 are described. A series of model sensitivity tests are conducted and compared with observations of total atmosphe...

306

Hydrolysis Reactions of the Taccalonolides Reveal Structure Activity Relationships  

PubMed Central

The taccalonolides are microtubule stabilizers isolated from plants of the genus Tacca that show potent in vivo antitumor activity and the ability to overcome multiple mechanisms of drug resistance. The most potent taccalonolide identified to date, AJ, is a semisynthetic product generated from the major plant metabolite, taccalonolide A, in a two-step reaction. The first step involves hydrolysis of taccalonolide A to generate taccalonolide B and then this product is oxidized to generate an epoxide group at C22-23. To generate sufficient taccalonolide AJ for in vivo antitumor efficacy studies, the hydrolysis conditions for the conversion of taccalonolide A to B were optimized. During purification of the hydrolysis products, we identified the new taccalonolide, AO (1) along with taccalonolide I. When the same hydrolysis reaction was performed on a taccalonolide E-enriched fraction four new taccalonolides, assigned to AK, AL, AM, and AN (2–5), were obtained in addition to the expected product taccalonolide N. Biological assays were performed on each of the purified taccalonolides which allowed for increased refinement of the structure-activity relationship of this class of compounds. PMID:23855953

Li, Jing; Peng, Jiangnan; Risinger, April L.; Mooberry, Susan L.

2013-01-01

307

HYDROLYSIS OF CHLORPYRIFOS IN AQUEOUS AND COLLOIDAL SYSTEMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hydrolysis of chlorpyrifos [o,o-diethyl o-(3, 5, 6-trichloro-2-pyridyl) phosphorothioate] to TCP (3,5,6-trichloro-2-pyridinol) is an important degradation process influencing the fate of chlorpyrifos in aquatic environments. The effects of water chemistry and suspended colloids (smectites, humic ac...

308

Hydrolysis of ferric ion in water and conformational equilibrium  

E-print Network

Reported here are results of theoretical calculations on the hexaaquoferric complex and deprotonated products to investigate the molecular mechanisms of hydrolysis of ferric ion in water. The combination of density functional electronic structure techniques and a dielectric continuum model for electrostatic solvation applied to the Fe(H$_2$O)$_6

Martin, R L E; Pratt, L R; Martin, Richard L.; Pratt, Lawrence R.

1998-01-01

309

Optimization of the enzymatic hydrolysis of Blue shark skin.  

PubMed

Enzymatic hydrolysis of Blue shark skin using Protamex™ was evaluated seeking optimal process conditions. The influence of temperature (45 to 65 °C), pH (6.8 to 8), and enzyme/substrate ratio (E/S; 1% to 5%) on the responses of degree of hydrolysis and protein recovery were determined and process optimization was performed looking for maximum value of the responses. Optimum conditions were established (T = 51 °C, E/S = 4%, and pH = 7.1) and model validation was accomplished by triplicate. Under these conditions protein hydrolysates were prepared and characterized by their amino acid composition, peptide size distribution, and antioxidant capacity by ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays. A degree of hydrolysis of 19.3% and protein recovery of 90.3% were obtained at optimal conditions. Chemical score indicated that the hydrolysate supplies minimal essential amino acid requirements for adults. Molecular weight of peptides on the hydrolysate was below 6.5 kDa. Enzymatic hydrolysis process was efficient for recovery of low molecular weight peptides with important nutritional content and antioxidant activity (FRAP = 12 ?mol eq. in FeSO(4).7H(2)O/g of protein, TEAC = 225.3 ?mol eq. in trolox/g of protein). PMID:22417547

Rodríguez-Díaz, Julio C; Kurozawa, Louise E; Netto, Flavia M; Hubinger, Miriam D

2011-09-01

310

Hydrolysis of lignocellulosic materials for ethanol production: a review  

Microsoft Academic Search

Lignocellulosic biomass can be utilized to produce ethanol, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars, and fermentation of the sugars to ethanol. The cost of ethanol production from lignocellulosic materials is relatively high based on current technologies,

Ye Sun; Jiayang Cheng

2002-01-01

311

The Preparation and Enzymatic Hydrolysis of a Library of Esters  

ERIC Educational Resources Information Center

An investigative case study involving the preparation of a library of esters using Fischer esterification and alcoholysis of acid chlorides and their subsequent enzymatic hydrolysis by pig liver esterase and orange peel esterase is described. Students work collaboratively to prepare and characterize the library of esters and complete and evaluate…

Sanford, Elizabeth M.; Smith, Traci L.

2008-01-01

312

Oxygen-17 NMR studies on uranium (VI) hydrolysis and gelation  

SciTech Connect

Hydrolysis and gelation processes in uranyl solutions are observed using the strong sharp uranyl oxygen-17 resonance. The ability to follow the hydrolysis of uranyl salts by observation of the sharp uranyl oxygen-17 resonance provides a clear indication of the dependence of uranyl hydrolysis on the counteranion (nitrate versus chloride) but not on the means of introducing hydroxide into the solution (Me{sub 4}NOH versus R{sub 3}N extraction). In addition, two different pathways for gelation are suggested. In the first pathway the uranyl hydrolysis is conducted with a base (HMTA in these studies) which preferentially forms trimeric (UO{sub 2}){sub 3} ({mu}{sub 3}-O) units which can then condense into the polymeric UO{sub 2}O{sub 6/3} layers of a gel based on the hexagonal structure of {proportional_to}UO{sub 2}(OH){sub 2}. In the second gelation pathway a uranyl derivative is treated with excess hydroxide in the absence of a metal or hydrogen-bonding ammonium cations which form insoluble solids uranates. Consensation of the resulting solution of soluble UO{sub 2}(OH)n{sup 2-n} anions can then lead to a similar polymer UO{sub 2}O{sub 4/2} or UO{sub 2}O{sub 6/3} structure of a gel. 9 refs., 2 figs.

King, R.B. [Georgia Univ., Athens, GA (United States). Dept. of Chemistry; King, C.M. [Westinghouse Savannah River Co., Aiken, SC (United States); Garber, A.R. [South Carolina Univ., Columbia, SC (United States). Dept. of Chemistry

1989-12-31

313

Oxygen-17 NMR studies on uranium (VI) hydrolysis and gelation  

SciTech Connect

Hydrolysis and gelation processes in uranyl solutions are observed using the strong sharp uranyl oxygen-17 resonance. The ability to follow the hydrolysis of uranyl salts by observation of the sharp uranyl oxygen-17 resonance provides a clear indication of the dependence of uranyl hydrolysis on the counteranion (nitrate versus chloride) but not on the means of introducing hydroxide into the solution (Me{sub 4}NOH versus R{sub 3}N extraction). In addition, two different pathways for gelation are suggested. In the first pathway the uranyl hydrolysis is conducted with a base (HMTA in these studies) which preferentially forms trimeric (UO{sub 2}){sub 3} ({mu}{sub 3}-O) units which can then condense into the polymeric UO{sub 2}O{sub 6/3} layers of a gel based on the hexagonal structure of {proportional to}UO{sub 2}(OH){sub 2}. In the second gelation pathway a uranyl derivative is treated with excess hydroxide in the absence of a metal or hydrogen-bonding ammonium cations which form insoluble solids uranates. Consensation of the resulting solution of soluble UO{sub 2}(OH)n{sup 2-n} anions can then lead to a similar polymer UO{sub 2}O{sub 4/2} or UO{sub 2}O{sub 6/3} structure of a gel. 9 refs., 2 figs.

King, R.B. (Georgia Univ., Athens, GA (United States). Dept. of Chemistry); King, C.M. (Westinghouse Savannah River Co., Aiken, SC (United States)); Garber, A.R. (South Carolina Univ., Columbia, SC (United States). Dept. of Chemistry)

1989-01-01

314

Ethanol production with dilute acid hydrolysis using partially dried lignocellulosics  

DOEpatents

A process of converting lignocellulosic biomass to ethanol, comprising hydrolyzing lignocellulosic materials by subjecting dried lignocellulosic material in a reactor to a catalyst comprised of a dilute solution of a strong acid and a metal salt to lower the activation energy (i.e., the temperature) of cellulose hydrolysis and ultimately obtain higher sugar yields.

Nguyen, Quang A. (Chesterfield, MO); Keller, Fred A. (Lakewood, CO); Tucker, Melvin P. (Lakewood, CO)

2003-12-09

315

DETERMINATION OF PENTACHLOROPHENOL IN URINE: THE IMPORTANCE OF HYDROLYSIS  

EPA Science Inventory

A gas chromatographic method for more reliable determination of pentachlorophenol (PCP) in urine has been developed. After hydrolysis and extraction the sample was reacted with diazomethane to produce the methyl ether of PCP prior to analysis by electron-capture gas chromatograph...

316

Structural modifications of lignocellulosics by pretreatments to enhance enzymatic hydrolysis  

Microsoft Academic Search

In this work an evaluation was made of a wide variety of single and multiple pretreatment methods for enhancing the rate of enzymatic hydrolysis of wheat straw. A multiple pretreatment consisted of a physical pretreatment followed by a chemical pretreatment. The structural features of wheat straw, including the specific surface area, crystallinity index, and lignin content, were measured to understand

M. M. Gharpuray; Yong-Hyun Lee; L. T. Fan

1983-01-01

317

DFT STUDY OF THE HYDROLYSIS OF SOME S-TRIAZINES  

EPA Science Inventory

The acid-catalyzed hydrolysis of atrazine and related 2-chloro-s-triazines to the corresponding 2-hydroxy-s-triazines was investigated using the B3LYP hybrid density functional theory method. Gas-phase calculations were performed at the B3LYP/6-311++G(d,p)//B3LYP/6-31G* level of ...

318

Hydrolysis of hemicellulose to produce fermentable monosaccharides by plasma acid.  

PubMed

In this paper, plasma acid was obtained by treating distilled water with dielectric barrier discharge to hydrolyze hemicellulose. The orthogonal experiment L??(5(6)) was used to optimize such hydrolysis conditions. The total reducing sugar (TRS) was measured by the DNS method. To determine whether the oligosaccharide existed in the hydrolysis products, it was hydrolyzed by sulfuric acid for a second time following the same procedure as reported earlier. The monosaccharide compositions of the hydrolyzed sample were analyzed by high-performance liquid chromatography (HPLC) and Fourier transformed infrared spectroscopy (FTIR). The results showed that pH 2.81 of plasma acid, 100 °C and 50 min were assigned as an optimal hydrolysis condition by plasma acid. Under this condition, the hemicellulose was hydrolyzed completely to produce monosaccharides including xylose, glucose, and galactose with the mole ratio being 17:3:1. The yields of xylose, glucose, and galactose were 38.67%, 9.28% and 3.09%, respectively. Compared with the hemicellulose hydrolysis results by sulfuric acid, it is concluded that plasma acid is an environmental-friendly and efficient method to explore and hydrolyze the hemicellulose existed in biomass. PMID:23911479

Wang, Ying; Yuan, Bo; Ji, Yingchao; Li, Hong

2013-09-12

319

A rapid microassay to evaluate enzymatic hydrolysis of lignocellulosic substrates.  

PubMed

Current attempts to produce ethanol from lignocellulosic biomass are focused on the optimization of pretreatment to reduce substrate recalcitrance and the improvement of enzymes for hydrolysis of the cellulose and hemicellulose components to produce fermentable sugars. Research aimed at optimizing both aspects of the bioconversion process involves assessment of the effects of multiple variables on enzyme efficiency, resulting in large factorial experiments with intensive assay requirements. A rapid assay for lignocellulose hydrolysis has been developed to address this need. Pretreated lignocellulose is formed into handsheets, which are then used to prepare small disks that are easily dispensed into microtiter plates. The hydrolysis of cellulose to glucose is estimated using an enzyme-coupled spectrophotometric assay. Using disks prepared from ethanol organosolv pretreated yellow poplar, it is shown that the assay generates data comparable with those produced by hydrolysis of pretreated yellow poplar pulp in Erlenmeyer flasks, followed by HPLC analysis of glucose. The assay shows considerable time and cost benefits over the standard assay protocol and is applicable to a broad range of lignocellulosic substrates. PMID:16345088

Berlin, Alex; Maximenko, Vera; Bura, Renata; Kang, Kyu-Young; Gilkes, Neil; Saddler, Jack

2006-04-01

320

Rapid method for detection of urea hydrolysis by yeasts.  

PubMed Central

A method is described for the rapid detection of urea hydrolysis by yeasts, using the Berthelot color reaction. The results could be determined within 30 to 50 min with this method, compared with 8 to 72 h usually required with Christensen urea agar. PMID:322609

Paliwal, D K; Randhawa, H S

1977-01-01

321

Evaluation of Cation Hydrolysis Schemes with a Pocket Calculator.  

ERIC Educational Resources Information Center

Described is the use of two models of pocket calculators. The Hewlett-Packard HP67 and the Texas Instruments TI59, to solve problems arising in connection with ionic equilibria in solution. A three-parameter regression program is described and listed as a specific example, the hydrolysis of hexavalent uranium, is provided. (BT)

Clare, Brian W.

1979-01-01

322

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

2013-07-01

323

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

2012-07-01

324

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

2011-07-01

325

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.  

...2014-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

2014-07-01

326

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions. ...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions. ...substance identified as hydrated alkaline earth metal salts of metalloid...

2010-07-01

327

common and distinct specificities at different sites of hydrolysis. (3-lactoglobulin hydroly-  

E-print Network

common and distinct specificities at different sites of hydrolysis. (3-lactoglobulin hydroly- sis in allergenic protein hydrolysis in humans) are present as early as birth in both species. The early high level

Boyer, Edmond

328

Conversion of fructose, glucose, and cellulose to 5-hydroxymethylfurfural by alkaline earth phosphate catalysts in hot compressed water.  

PubMed

The phosphates of alkaline earth metals (calcium and strontium) synthesized by precipitation process in acetone-water media system were used as catalysts for converting fructose, glucose, and cellulose to 5-hydroxymethylfurfural (HMF) under hot compressed water condition. It was found that the phosphates of calcium and strontium effectively catalyzed the HMF formation from fructose and glucose dehydration and cellulose hydrolysis/dehydration reaction, as compared with the non-catalytic system. The XRD analysis confirmed the CaP(2)O(6) and ?-Sr(PO(3))(2) crystalline phases of the catalyst samples, while acid strength of both catalysts was in a range of +3.3 ? H(0) ? +4.8. From the study, CaP(2)O(6) and ?-Sr(PO(3))(2) showed similar catalytic performance toward the dehydration of sugars, providing the HMF yields of 20-21% and 34-39% from glucose and fructose, respectively; whereas the total yield of glucose and HMF from the hydrolysis/dehydration of cellulose over ?-Sr(PO(3))(2) (34%) was higher than that over CaP(2)O(6) (17.4%). PMID:23123573

Daorattanachai, Pornlada; Khemthong, Pongtanawat; Viriya-Empikul, Nawin; Laosiripojana, Navadol; Faungnawakij, Kajornsak

2012-12-01

329

Hydrolysis of the energetic materials present in a composite modified double base solid rocket propellant  

Microsoft Academic Search

The aqueous hydrolysis of the nitroglycerin (NG), nitrocellulose (NC), and HMX present in CYH, a composite modified double base solid propellant, was successfully performed using either sodium hydroxide (NaOH) or ammonia (NH3) as hydrolyzing agents. The rate of hydrolysis was faster for NaOH compared to NH3. For both hydrolysis agents the rate of hydrolysis of NG was the fastest, followed

Louis F. Cannizzo; Glenn L. Mower; Lewis R. Hunstman; Walter R. Achatz; W. Wayne Edwards

1995-01-01

330

Enzymatic hydrolysis of cellulose materials treated with ionic liquid [BMIM] Cl  

Microsoft Academic Search

A new cellulose solvent ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) was used to treat wheat straw and steam-exploded\\u000a wheat straw (SEWS) in order to improve the enzymatic hydrolysis rates, while the water was used as the control. The enzymatic\\u000a hydrolysis results showed that the hydrolysis rates of materials treated with [BMIM]Cl were improved. The hydrolysis rate\\u000a of treated wheat straw could

Liying Liu; Hongzhang Chen

2006-01-01

331

MATHEMATICAL MODELING OF ENZYMATIC HYDROLYSIS OF STARCH: APPLICATION TO FUEL ETHANOL PRODUCTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Enzymatic hydrolysis of starch in corn is an important step that determines fermentation efficiency. Corn genetics, post harvest handling and process conditions are factors that affect starch hydrolysis. There is a lack of mathematical models for starch hydrolysis in the dry grind corn process tha...

332

A new class of inhibitors of 2-arachidonoylglycerol hydrolysis and invasion of prostate cancer cells q  

E-print Network

A new class of inhibitors of 2-arachidonoylglycerol hydrolysis and invasion of prostate cancer-independent prostate cancer cells. Blocking cellular hydrolysis of 2-AG to increase its endogenous concentration to inhibit 2-AG hydrolysis and prostate cancer cell invasion. Compounds containing a thioether b to a TFK

Hammock, Bruce D.

333

An Overview of Chemical Processes That Damage Cellular DNA: Spontaneous Hydrolysis, Alkylation, and Reactions with Radicals  

E-print Network

ReViews An Overview of Chemical Processes That Damage Cellular DNA: Spontaneous Hydrolysis damage under physiological conditions. Contents 1. Introduction 1747 2. Hydrolysis of DNA 1747 2.1. Spontaneous Hydrolysis of the Phosphodiester Backbone Is Very Slow 1747 2.2. Hydrolytic Deamination of DNA

Gates, Kent. S.

334

Changes in the Enzymatic Hydrolysis Rate of Avicel Cellulose With Conversion  

E-print Network

hydrolysis. Then, the solids were treated with proteinase to degrade the cellulase enzymes remaining with water, 1.0 M NaCl solution, and water. Next, fresh cellulase and buffer were added to the solids. Keywords: cellulase; cellulose; enzymatic hydrolysis; restarted hydrolysis; substrate reactivity

California at Riverside, University of

335

Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems  

Microsoft Academic Search

Information pertaining to enzymatic hydrolysis of cellulose by noncomplexed cellulase enzyme systems is reviewed with a particular emphasis on development of aggregated understanding incorporating substrate features in addition to concentration and multiple cellulase compo- nents. Topics considered include properties of cellulose, adsorption, cellulose hydrolysis, and quantitative models. A classification scheme is proposed for quantitative models for enzymatic hydrolysis of cellulose

Yi-Heng Percival Zhang; Lee R. Lynd

2004-01-01

336

Organized Unidirectional Waves of ATP Hydrolysis within a RecA Filament  

E-print Network

Organized Unidirectional Waves of ATP Hydrolysis within a RecA Filament Julia M. Cox, Oleg V on opposite filament ends, with disassembly requiring ATP hydrolysis. When filaments form on duplex DNA, Rec. RecA filament state was monitored with a coupled spectrophotometric assay for ATP hydrolysis

Cox, Michael M.

337

Enzymatic Hydrolysis of Cellulose Coupled With Electricity Generation in a Microbial Fuel Cell  

E-print Network

ARTICLE Enzymatic Hydrolysis of Cellulose Coupled With Electricity Generation in a Microbial Fuel hydrolysis rates of the particles. Cellulases are used to achieve rapid conversion of cellulose to sugar%, likely as a result of rapid hydrolysis of cellulose in the reactor and biodegradation of the enzyme

338

Effects of Hydrolysis on Force Generation by Actin Filaments A. E. Carlsson  

E-print Network

Effects of Hydrolysis on Force Generation by Actin Filaments A. E. Carlsson Department of Physics, Washington University, St. Louis, MO 63130 (Dated: October 1, 2007) Abstract The effects of ATP hydrolysis motion. This results either directly or indirectly from hydrolysis, during which a molecule of adenosine

Carlsson, Anders

339

ATP Hydrolysis Enhances RNA Recognition and Antiviral Signal Transduction by the Innate Immune Sensor,  

E-print Network

ATP Hydrolysis Enhances RNA Recognition and Antiviral Signal Transduction by the Innate Immune receptor required for innate antiviral signaling. Results: LGP2 uses ATP hydrolysis to diversify RNA infec- tion and initiate antiviral signal transduction cascades. The ATP hydrolysis activity of LGP2

Myong, Sua

340

vation of significant population shifts. Due to its slower rate of hydrolysis, it is possi-  

E-print Network

vation of significant population shifts. Due to its slower rate of hydrolysis, it is possi- ble that resistant starch is degraded through- out the colon while lactulose hydrolysis and fermentation mainly occur the interactions that occur during starch hydrolysis between Bac- teroides thetaiotaomicron, a hydrolytic bac

Paris-Sud XI, Université de

341

Fast Hemicellulose Quantification Via a Simple One-Step Acid Hydrolysis  

E-print Network

Fast Hemicellulose Quantification Via a Simple One-Step Acid Hydrolysis Xiadi Gao,1,2,3 Rajeev hydrolysis method was developed, which applied 4 wt% sulfuric acid at 121 C for 1 h to rapidly quantify XGM-step acid hydrolysis while significantly shortening analysis time. Biotechnol. Bioeng. 2014;111: 1088

California at Riverside, University of

342

On a Three Step Model of Anaerobic Digestion Including the Hydrolysis of  

E-print Network

On a Three Step Model of Anaerobic Digestion Including the Hydrolysis of Particulate Matter R of hydrolysis in the appearance of positive equilibrium points and the bistability is pointed out. If a non, the anaerobic digestion is generally considered as a three step process: hydrolysis and liquefaction

Paris-Sud XI, Université de

343

Molecular dissection of the roles of nucleotide binding and hydrolysis in dynein's AAA domains  

E-print Network

Molecular dissection of the roles of nucleotide binding and hydrolysis in dynein's AAA domains of nucleotide binding and hydrolysis in each of these four AAA domains has constituted an important and unre as a model system, we mutagenized residues involved in nucleotide binding or hydrolysis in the four AAA

Vale, Ronald D.

344

RecA-mediated SOS induction requires an extended filament conformation but no ATP hydrolysis  

E-print Network

RecA-mediated SOS induction requires an extended filament conformation but no ATP hydrolysis induction in vivo after UV treatment. Thus, SOS induction does not require ATP hydrolysis by the Rec an improved reagent for studies of the function of ATP hydrolysis by RecA in vivo and in vitro. Introduction

Cox, Michael M.

345

Brownian Ratchets Driven by Asymmetric Nucleation of Hydrolysis Waves Amit Lakhanpal and Tom Chou  

E-print Network

Brownian Ratchets Driven by Asymmetric Nucleation of Hydrolysis Waves Amit Lakhanpal and Tom Chou that asymmetric nucleation of hydrolysis waves on a track can also result in directed motion of an attached, myosins, helicases, and polymerases convert part of the free energy of, e.g., ATP hydrolysis

Chou, Tom

346

Role of ATP-Hydrolysis in the Dynamics of a Single Actin Filament Padinhateeri Ranjith,  

E-print Network

Role of ATP-Hydrolysis in the Dynamics of a Single Actin Filament Padinhateeri Ranjith, * Kirone, and ATP hydrolysis of subunits either according to the vectorial mechanism or to the random mechanism. In a previous work, we developed a model for a single actin or microtubule filament where hydrolysis occurred

Lacoste, David

347

Effect of lactose hydrolysis on calcium absorption during duodenal milk perfusion  

E-print Network

Effect of lactose hydrolysis on calcium absorption during duodenal milk perfusion Ines BIRLOUEZ, Skala and Bakos, 1973). However, as yet there is little direct evidence that such hydrolysis show the role of lactose hydrolysis ; such a study was carried out by Debongnie et al. (1979), but only

Paris-Sud XI, Université de

348

QUALITATIVE PROPERTIES OF A 3-STEPS MODEL OF ANAEROBIC DIGESTION INCLUDING HYDROLYSIS OF PARTICULATE MATTER  

E-print Network

QUALITATIVE PROPERTIES OF A 3-STEPS MODEL OF ANAEROBIC DIGESTION INCLUDING HYDROLYSIS, the anaerobic digestion is generally considered as a three step process: hydrolysis and liquefaction the hydrolysis is still an open problem. Many chemists claim that this is a pure enzymatic phenomena while

Paris-Sud XI, Université de

349

4-Methylhomoibotenic Acid Activates a Novel Metabotropic Glutamate Receptor Coupled to Phosphoinositide Hydrolysis1  

E-print Network

to Phosphoinositide Hydrolysis1 DOROTHY S. CHUNG, STEPHEN F. TRAYNELIS, T. J. MURPHY and P. JEFFREY CONN DepartmentGluR1 and mGluR5 are coupled to phosphoinositide hydrolysis in expression systems, and both the phosphoinositide hydrolysis response to DHPG in rat cortical slices. In contrast, LY341495 did not block

Traynelis, Stephen F.

350

Investigation of a New Thermosensitive Block Copolymer Micelle: Hydrolysis, Disruption, and Release  

E-print Network

Investigation of a New Thermosensitive Block Copolymer Micelle: Hydrolysis, Disruption, and Release design that is based on the use of one block bearing a thermally labile side group, whose hydrolysis upon)methacrylamide lactate) (NHPMAAm- lactate).5 At physiological conditions (pH 7.4, 37 °C), the hydrolysis of the lactate

Zhao, Yue

351

Dipeptide hydrolysis by the dinuclear zinc enzyme human renal dipeptidase: Mechanistic insights from DFT calculations  

E-print Network

Dipeptide hydrolysis by the dinuclear zinc enzyme human renal dipeptidase: Mechanistic insights dipeptidase is investigated using hybrid density functional theory. This enzyme catalyzes the hydrolysis the hydrolysis of dipeptides with D-, L-, or dehydro-amino acids at the C-terminus (Scheme 1) [1­3]. It plays

Liao, Rongzhen

352

Characterization of the degree of polymerization of xylooligomers produced by flowthrough hydrolysis of pure xylan  

E-print Network

hydrolysis of pure xylan and corn stover with water Bin Yang, Charles E. Wyman * Center for Environmental, although hemicellulose hydrolysis is virtually always assumed to follow first-order homogeneous kinetics for these difference is that lignin and lignin­ xylan compounds in particular play an important role in the hydrolysis

California at Riverside, University of

353

A molecular switch in SecA protein couples ATP hydrolysis to protein translocation  

E-print Network

A molecular switch in SecA protein couples ATP hydrolysis to protein translocation SpyridoulaA dimers. NBD1 is suffi- cient for single rounds of SecA ATP hydrolysis. Multi- ple ATP turnovers at NBD1. This intramolecular regulator of ATP hydrolysis (IRA) mediates N-/C-domain binding and acts as a molecular switch

Economou, Tassos

354

Application of High Throughput Pretreatment and Co-Hydrolysis System to Thermochemical  

E-print Network

ARTICLE Application of High Throughput Pretreatment and Co-Hydrolysis System to Thermochemical release from the coupled operations of pretreat- ment and enzymatic hydrolysis are extremely time and material intensive, high throughput (HT) pretreatment and enzymatic hydrolysis systems have become vital

California at Riverside, University of

355

The Reaction Mechanism of Paraoxon Hydrolysis by Phosphotriesterase from Combined QM/MM Simulations  

E-print Network

The Reaction Mechanism of Paraoxon Hydrolysis by Phosphotriesterase from Combined QM/MM Simulations Submitted to Biochemistry #12;1 The Reaction Mechanism of Paraoxon Hydrolysis by Phosphotriesterase from of Paraoxon Hydrolysis by Phosphotriesterase Page 1 of 57 ACS Paragon Plus Environment Submitted

Minnesota, University of

356

Microbial Thiocyanate Utilization under Highly Alkaline Conditions  

PubMed Central

Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS?) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase activity which converted cyanate (CNO?) to ammonia and CO2. On the other hand, cyanase activity either was absent or was present at very low levels in the autotrophic strains grown on thiocyanate as the sole energy and N source. As a result, large amounts of cyanate were found to accumulate in the media during utilization of thiocyanate at pH 10 in batch and thiocyanate-limited continuous cultures. This is a first direct proof of a “cyanate pathway” in pure cultures of thiocyanate-degrading bacteria. Since it is relatively stable under alkaline conditions, cyanate is likely to play a role as an N buffer that keeps the alkaliphilic bacteria safe from inhibition by free ammonia, which otherwise would reach toxic levels during dissimilatory degradation of thiocyanate. PMID:11157213

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

2001-01-01

357

Net alkalinity and net acidity 2: Practical considerations  

USGS Publications Warehouse

The pH, alkalinity, and acidity of mine drainage and associated waters can be misinterpreted because of the chemical instability of samples and possible misunderstandings of standard analytical method results. Synthetic and field samples of mine drainage having various initial pH values and concentrations of dissolved metals and alkalinity were titrated by several methods, and the results were compared to alkalinity and acidity calculated based on dissolved solutes. The pH, alkalinity, and acidity were compared between fresh, unoxidized and aged, oxidized samples. Data for Pennsylvania coal mine drainage indicates that the pH of fresh samples was predominantly acidic (pH 2.5-4) or near neutral (pH 6-7); ??? 25% of the samples had pH values between 5 and 6. Following oxidation, no samples had pH values between 5 and 6. The Standard Method Alkalinity titration is constrained to yield values >0. Most calculated and measured alkalinities for samples with positive alkalinities were in close agreement. However, for low-pH samples, the calculated alkalinity can be negative due to negative contributions by dissolved metals that may oxidize and hydrolyze. The Standard Method hot peroxide treatment titration for acidity determination (Hot Acidity) accurately indicates the potential for pH to decrease to acidic values after complete degassing of CO2 and oxidation of Fe and Mn, and it indicates either the excess alkalinity or that required for neutralization of the sample. The Hot Acidity directly measures net acidity (= -net alkalinity). Samples that had near-neutral pH after oxidation had negative Hot Acidity; samples that had pH < 6.3 after oxidation had positive Hot Acidity. Samples with similar pH values before oxidation had dissimilar Hot Acidities due to variations in their alkalinities and dissolved Fe, Mn, and Al concentrations. Hot Acidity was approximately equal to net acidity calculated based on initial pH and dissolved concentrations of Fe, Mn, and Al minus the initial alkalinity. Acidity calculated from the pH and dissolved metals concentrations, assuming equivalents of 2 per mole of Fe and Mn and 3 per mole of Al, was equivalent to that calculated based on complete aqueous speciation of FeII/FeIII. Despite changes in the pH, alkalinity, and metals concentrations, the Hot Acidities were comparable for fresh and most aged samples. A meaningful "net" acidity can be determined from a measured Hot Acidity or by calculation from the pH, alkalinity, and dissolved metals concentrations. The use of net alkalinity = (Alkalinitymeasured - Hot Aciditymeasured) to design mine drainage treatment can lead to systems with insufficient Alkalinity to neutralize metal and H+ acidity and is not recommended. The use of net alkalinity = -Hot Acidity titration is recommended for the planning of mine drainage treatment. The use of net alkalinity = (Alkalinitymeasured - Aciditycalculated) is recommended with some cautions. ?? 2005 Elsevier Ltd. All rights reserved.

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

2005-01-01

358

Purification and characterization of neutral and alkaline invertase from carrot.  

PubMed Central

Neutral and alkaline invertase were identified in cells of a suspension culture of carrot (Daucus carota L.) and purified to electrophoretic homogeneity. Neutral invertase is an octamer with a molecular mass of 456 kD and subunits of 57 kD, whereas alkaline invertase is a tetramer with a molecular mass of 504 kD and subunits of 126 kD. Both enzymes had sharp pH profiles, with maximal activities at pH 6.8 for neutral invertase and pH 8.0 for alkaline invertase, and both hydrolyzed sucrose with typical hyperbolic kinetics and similar Km values of about 20 mM at pH 7.5. Neutral invertase also hydrolyzed raffinose and stachyose and, therefore, is a beta-fructofuranosidase. In contrast, alkaline invertase was highly specific for sucrose. Fructose acted as a competitive inhibitor of both enzymes, with Ki values of about 15 mM. Glucose was a noncompetitive inhibitor of both neutral and alkaline invertase, with a Ki of about 30 mM. Neither enzyme was inhibited by HgCl2. Alkaline invertase was markedly inhibited by CaCl2, MgCl2, and MnCl2, and neutral invertase was not. In contrast to alkaline invertase, neutral invertase was inhibited by the nucleotides ATP, CTP, GTP, and UTP. PMID:8972597

Lee, H S; Sturm, A

1996-01-01

359

Francisella DnaK Inhibits Tissue-nonspecific Alkaline Phosphatase*  

PubMed Central

Following pulmonary infection with Francisella tularensis, we observed an unexpected but significant reduction of alkaline phosphatase, an enzyme normally up-regulated following inflammation. However, no reduction was observed in mice infected with a closely related Gram-negative pneumonic organism (Klebsiella pneumoniae) suggesting the inhibition may be Francisella-specific. In similar fashion to in vivo observations, addition of Francisella lysate to exogenous alkaline phosphatase (tissue-nonspecific isozyme) was inhibitory. Partial purification and subsequent proteomic analysis indicated the inhibitory factor to be the heat shock protein DnaK. Incubation with increasing amounts of anti-DnaK antibody reduced the inhibitory effect in a dose-dependent manner. Furthermore, DnaK contains an adenosine triphosphate binding domain at its N terminus, and addition of adenosine triphosphate enhances dissociation of DnaK with its target protein, e.g. alkaline phosphatase. Addition of adenosine triphosphate resulted in decreased DnaK co-immunoprecipitated with alkaline phosphatase as well as reduction of Francisella-mediated alkaline phosphatase inhibition further supporting the binding of Francisella DnaK to alkaline phosphatase. Release of DnaK via secretion and/or bacterial cell lysis into the extracellular milieu and inhibition of plasma alkaline phosphatase could promote an orchestrated, inflammatory response advantageous to Francisella. PMID:22923614

Arulanandam, Bernard P.; Chetty, Senthilnath Lakshmana; Yu, Jieh-Juen; Leonard, Sean; Klose, Karl; Seshu, Janakiram; Cap, Andrew; Valdes, James J.; Chambers, James P.

2012-01-01

360

Bioethanol production: an integrated process of low substrate loading hydrolysis-high sugars liquid fermentation and solid state fermentation of enzymatic hydrolysis residue.  

PubMed

An integrated process of enzymatic hydrolysis and fermentation was investigated for high ethanol production. The combination of enzymatic hydrolysis at low substrate loading, liquid fermentation of high sugars concentration and solid state fermentation of enzymatic hydrolysis residue was beneficial for conversion of steam explosion pretreated corn stover to ethanol. The results suggested that low substrate loading hydrolysis caused a high enzymatic hydrolysis yield; the liquid fermentation of about 200g/L glucose by Saccharomyces cerevisiae provided a high ethanol concentration which could significantly decrease cost of the subsequent ethanol distillation. A solid state fermentation of enzymatic hydrolysis residue was combined, which was available to enhance ethanol production and cellulose-to-ethanol conversion. The results of solid state fermentation demonstrated that the solid state fermentation process accompanied by simultaneous saccharification and fermentation. PMID:22975252

Chu, Qiulu; Li, Xin; Ma, Bin; Xu, Yong; Ouyang, Jia; Zhu, Junjun; Yu, Shiyuan; Yong, Qiang

2012-11-01

361

Efficient utilization of licorice root by alkaline extraction.  

PubMed

Compared to studies of water extracts of plants, those utilising alkaline extracts are limited. Both water and alkaline extracts from licorice root were compared regarding their biological activities. Licorice root was successively extracted first with water or alkaline solution (pH 9 or 12), and the alkaline (pH 12.0) extract was further separated into 50% ethanol-soluble and -insoluble fractions. Viable cell number was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Antibacterial activity against Porphyromonas gingivalis 381 was determined by turbidity assay. Cytochrome P-450 (CYP)3A4 activity was measured by ?-hydroxylation of testosterone using human recombinant CYP3A4. Radical intensity of superoxide and hydroxyl radicals was determined by electron spin resonance spectroscopy. Alkaline extraction yielded slightly higher amounts of dried materials compared to water extraction. Alkaline extract showed higher anti-HIV and antibacterial activities, and similar magnitudes of CYP3A4 inhibitory and superoxide and hydroxyl radical-scavenging activities, compared to water extract. When alkaline extract was fractionated by 50% ethanol, anti-HIV activity was recovered from the insoluble fraction representing approximately 3% of the alkaline extract, whereas antibacterial activity was concentrated in the soluble fraction rich in glycyrrhizid acid, flavanones and chalcones. All extracts and sub-fractions led to bimodal hormetic dose-response (maximum hormetic response=238%) on the bacterial growth. The present study demonstrated the superiority of alkaline extraction over water extraction for preparing anti-HIV and antibacterial agents at higher yield from licorice root. PMID:25189890

Ohno, Hirokazu; Miyoshi, Shozo; Araho, Daisuke; Kanamoto, Taisei; Terakubo, Shigemi; Nakashima, Hideki; Tsuda, Tadashi; Sunaga, Katsuyoshi; Amano, Shigeru; Ohkoshi, Emika; Sakagami, Hiroshi; Satoh, Kazue; Yamamoto, Masaji

2014-01-01

362

Water miscible mono alcohols' effect on the proteolytic performance of Bacillus clausii serine alkaline protease.  

PubMed

In this study, our investigations showed that the increasing concentrations of all examined mono alcohols caused a decrease in the Vm, kcat and kcat/Km values of Bacillus clausii GMBE 42 serine alkaline protease for casein hydrolysis. However, the Km value of the enzyme remained almost the same, which was an indicator of non-competitive inhibition. Whereas inhibition by methanol was partial non-competitive, inhibition by the rest of the alcohols tested was simple non-competitive. The inhibition constants (KI) were in the range of 1.32-3.10 M, and the order of the inhibitory effect was 1-propanol>2-propanol>methanol>ethanol. The ?G(?) and ?G(?)E-T values of the enzyme increased at increasing concentrations of all alcohols examined, but the ?G(?)ES value of the enzyme remained almost the same. The constant Km and ?G(?)ES values in the presence and absence of mono alcohols indicated the existence of different binding sites for mono alcohols and casein on enzyme the molecule. The kcat of the enzyme decreased linearly by increasing log P and decreasing dielectric constant (D) values, but the ?G(?) and ?G(?)E-T values of the enzyme increased by increasing log P and decreasing D values of the reaction medium containing mono alcohols. PMID:24092453

Duman, Yonca Avci; Kazan, Dilek; Denizci, Aziz Akin; Erarslan, Altan

2014-01-01

363

Enhanced catalysis by active-site mutagenesis at aspartic acid 153 in Escherichia coli alkaline phosphatase.  

PubMed

Bacterial alkaline phosphatase catalyzes the hydrolysis and transphosphorylation of phosphate monoesters. Site-directed mutagenesis was used to change the active-site residue Asp-153 to Ala and Asn. In the wild-type enzyme Asp-153 forms a second-sphere complex with Mg2+. The activity of mutant enzymes D153N and D153A is dependent on the inclusion of Mg2+ in the assay buffer. The steady-state kinetic parameters of the D153N mutant display small enhancements, relative to wild type, in buffers containing 10 mM Mg2+. In contrast, the D153A mutation gives rise to a 6.3-fold increase in kcat, a 13.7-fold increase in kcat/Km (50 mM Tris, pH 8), and a 159-fold increase in Ki for Pi (1 M Tris, pH 8). In addition, the activity of D153A increases 25-fold as the pH is increased from 7 to 9. D153A hydrolyzes substrates with widely differing pKa's of their phenolic leaving groups (PNPP and DNPP), at similar rates. As with wild type, the rate-determining step takes place after the initial nucleophilic displacement (k2). The increase in kcat for the D153A mutant indicates that the rate of release of phosphate from the enzyme product complex (k4) has been enhanced. PMID:1525159

Matlin, A R; Kendall, D A; Carano, K S; Banzon, J A; Klecka, S B; Solomon, N M

1992-09-01

364

Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal.  

PubMed

The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP) including ? and ? forms of isosaccharinic acid (ISA) and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n = 6, p = 0.118) in ? and ? ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7 × 10(-2) hr(-1) (SE ± 2.9 × 10(-3)). These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility. PMID:25268118

Rout, Simon P; Radford, Jessica; Laws, Andrew P; Sweeney, Francis; Elmekawy, Ahmed; Gillie, Lisa J; Humphreys, Paul N

2014-01-01

365

Development and operation of a hybrid acid-alkaline advanced water electrolysis cell  

NASA Astrophysics Data System (ADS)

A hybrid acid-alkaline water electrolysis cell has been developed for hydrogen production. The cell is based on the use of an acidic solution at the cathode and a basic solution at the anode to reduce the minimum theoretical voltage for water decomposition from the thermoneutral potential of 1.47 V to close to 1.4 V at 25 C and 1 atm. The pH differential is maintained by the removal of OH ions from the cathode section and water removal from the anode section, which can be driven by heat energy. A practical cell has been built using a solid polymer electrolyte in which, however, the cathodic compartment is not acidic but neutral. Tests with a platinum black cathode catalyst and a platinum-iridium anode catalyst have resulted in steady-state water hydrolysis at an applied voltage of 0.9 V, and a V-I diagram with a considerably lower slope than that of a conventional cell has been obtained at 90 C.

Teschke, O.; Zwanziger, M.

366

Biodegradation of the Alkaline Cellulose Degradation Products Generated during Radioactive Waste Disposal  

PubMed Central

The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP) including ? and ? forms of isosaccharinic acid (ISA) and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n?=?6, p?=?0.118) in ? and ? ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7×10?2 hr?1 (SE±2.9×10?3). These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility. PMID:25268118

Rout, Simon P.; Radford, Jessica; Laws, Andrew P.; Sweeney, Francis; Elmekawy, Ahmed; Gillie, Lisa J.; Humphreys, Paul N.

2014-01-01

367

Polyvinyl alcohol battery separator containing inert filler. [alkaline batteries  

NASA Technical Reports Server (NTRS)

A cross-linked polyvinyl alcohol battery separator is disclosed. A particulate filler, inert to alkaline electrolyte of an alkaline battery, is incorporated in the separator in an amount of 1-20% by weight, based on the weight of the polyvinyl alcohol, and is dispersed throughout the product. Incorporation of the filler enhances performance and increases cycle life of alkaline batteries when compared with batteries containing a similar separator not containing filler. Suitable fillers include titanates, silicates, zirconates, aluminates, wood floor, lignin, and titania. Particle size is not greater than about 50 microns.

Sheibley, D. W.; Hsu, L. C.; Manzo, M. A. (inventors)

1981-01-01

368

Method of increasing the sulfation capacity of alkaline earth sorbents  

DOEpatents

A system and method for increasing the sulfation capacity of alkaline earth carbonates to scrub sulfur dioxide produced during the fluidized bed combustion of coal in which partially sulfated alkaline earth carbonates are hydrated in a fluidized bed to crack the sulfate coating and convert the alkaline earth oxide to the hydroxide. Subsequent dehydration of the sulfate-hydroxide to a sulfate-oxide particle produces particles having larger pore size, increased porosity, decreased grain size and additional sulfation capacity. A continuous process is disclosed.

Shearer, J.A.; Turner, C.B.; Johnson, I.

1980-03-13

369

Process for treating alkaline wastes for vitrification  

DOEpatents

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

Hsu, Chia-lin W.

1994-01-01

370

Response of Desulfovibrio vulgaris to Alkaline Stress  

SciTech Connect

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

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

2007-11-30

371

Alkaline decomposition of synthetic jarosite with arsenic.  

PubMed

The widespread use of jarosite-type compounds to eliminate impurities in the hydrometallurgical industry is due to their capability to incorporate several elements into their structures. Some of these elements are of environmental importance (Pb(2+), Cr(6+), As(5+), Cd(2+), Hg(2+)). For the present paper, AsO4 (3-) was incorporated into the lattice of synthetic jarosite in order to carry out a reactivity study. Alkaline decomposition is characterized by removal of sulfate and potassium ions from the lattice and formation of a gel consisting of iron hydroxides with absorbed arsenate. Decomposition curves show an induction period followed by a conversion period. The induction period is independent of particle size and exponentially decreases with temperature. The conversion period is characterized by formation of a hydroxide halo that surrounds an unreacted jarosite core. During the conversion period in NaOH media for [OH(-)]?>?8?×?10(-3) mol L(-1), the process showed a reaction order of 1.86, and an apparent activation energy of 60.3 kJ mol(-1) was obtained. On the other hand, during the conversion period in Ca(OH)2 media for [OH(-)]?>?1.90?×?10(-2) mol L(-1), the reaction order was 1.15, and an apparent activation energy of 74.4 kJ mol(-1) was obtained. The results are consistent with the spherical particle model with decreasing core and chemical control. PMID:23566061

Patiño, Francisco; Flores, Mizraim U; Reyes, Iván A; Reyes, Martín; Hernández, Juan; Rivera, Isauro; Juárez, Julio C

2013-01-01

372

Process for treating alkaline wastes for vitrification  

DOEpatents

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

Hsu, Chia-lin W. (Augusta, GA)

1995-01-01

373

Process for treating alkaline wastes for vitrification  

DOEpatents

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

Hsu, C.L.W.

1995-07-25

374

Production of alkaline protease from Cellulosimicrobium cellulans  

PubMed Central

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

Ferracini-Santos, Luciana; Sato, Hélia H

2009-01-01

375

Production of alkaline protease from Cellulosimicrobium cellulans.  

PubMed

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

Ferracini-Santos, Luciana; Sato, Hélia H

2009-01-01

376

Switching catalysis from hydrolysis to perhydrolysis in P. fluorescens esterase  

PubMed Central

Many serine hydrolases catalyze perhydrolysis – the reversible formation of per-acids from carboxylic acids and hydrogen peroxide. Recently we showed that a single amino acid substitution in the alcohol binding pocket - L29P - in Pseudomonas fluorescens (SIK WI) aryl esterase (PFE) increased the specificity constant of PFE for peracetic acid formation >100-fold [Bernhardt et al. Angew. Chem. Intl. Ed. 2005, 44, 2742]. In this paper, we extend this work to address the three following questions. First, what is the molecular basis of the increase in perhydrolysis activity? We previously proposed that the L29P substitution creates a hydrogen bond between the enzyme and hydrogen peroxide in the transition state. Here we report two x-ray structures of L29P PFE that support this proposal. Both structures show a main chain carbonyl oxygen closer to the active-site serine as expected. One structure further shows acetate in the active site in an orientation consistent with reaction by an acyl-enzyme mechanism. We also detected an acyl-enzyme intermediate in the hydrolysis of ?-caprolactone by mass spectrometry. Second, can we further increase perhydrolysis activity? We discovered that the reverse reaction – hydrolysis of peracetic acid to acetic acid and hydrogen peroxide – occurs at nearly the diffusion limited rate. Since the reverse reaction cannot increase further, neither can the forward reaction. Consistent with this prediction, two variants with additional amino acid substitutions showed two fold higher kcat, but Km also increased so the specificity constant, kcat/Km, remained similar. Third, how does the L29P substitution change the esterase activity? Ester hydrolysis decreased for most esters (75-fold for ethyl acetate), but not for methyl esters. In contrast, L29P PFE catalyzed hydrolysis of ?-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the active site blocks access for larger alcohol moieties, but binds ?-caprolactone more tightly. These results are consistent with the natural function of perhydrolases being either hydrolysis of peroxycarboxylic acids or hydrolysis of lactones. PMID:20112920

Yin, De Lu (Tyler); Bernhardt, Peter; Morley, Krista L.; Jiang, Yun; Cheeseman, Jeremy D.; Purpero, Vincent; Schrag, Joseph D.; Kazlauskas, Romas J.

2010-01-01

377

Switching Catalysis from Hydrolysis to Perhydrolysis in Pseudomonas fluorescens Esterase  

SciTech Connect

Many serine hydrolases catalyze perhydrolysis, the reversible formation of peracids from carboxylic acids and hydrogen peroxide. Recently, we showed that a single amino acid substitution in the alcohol binding pocket, L29P, in Pseudomonas fluorescens (SIK WI) aryl esterase (PFE) increased the specificity constant of PFE for peracetic acid formation >100-fold [Bernhardt et al. (2005) Angew. Chem., Int. Ed. 44, 2742]. In this paper, we extend this work to address the three following questions. First, what is the molecular basis of the increase in perhydrolysis activity? We previously proposed that the L29P substitution creates a hydrogen bond between the enzyme and hydrogen peroxide in the transition state. Here we report two X-ray structures of L29P PFE that support this proposal. Both structures show a main chain carbonyl oxygen closer to the active site serine as expected. One structure further shows acetate in the active site in an orientation consistent with reaction by an acyl-enzyme mechanism. We also detected an acyl-enzyme intermediate in the hydrolysis of {var_epsilon}-caprolactone by mass spectrometry. Second, can we further increase perhydrolysis activity? We discovered that the reverse reaction, hydrolysis of peracetic acid to acetic acid and hydrogen peroxide, occurs at nearly the diffusion limited rate. Since the reverse reaction cannot increase further, neither can the forward reaction. Consistent with this prediction, two variants with additional amino acid substitutions showed 2-fold higher k{sub cat}, but K{sub m} also increased so the specificity constant, k{sub cat}/K{sub m}, remained similar. Third, how does the L29P substitution change the esterase activity? Ester hydrolysis decreased for most esters (75-fold for ethyl acetate) but not for methyl esters. In contrast, L29P PFE catalyzed hydrolysis of {var_epsilon}-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the active site blocks access for larger alcohol moieties but binds {var_epsilon}-caprolactone more tightly. These results are consistent with the natural function of perhydrolases being either hydrolysis of peroxycarboxylic acids or hydrolysis of lactones.

Yin, D.; Bernhardt, P; Morley, K; Jiang, Y; Cheeseman, J; Purpero, V; Schrag, J; Kazlauskas, R

2010-01-01

378

A mechanism of catalyzed GTP hydrolysis by Ras protein through magnesium ion  

NASA Astrophysics Data System (ADS)

The hydrolysis by Ras plays pivotal roles in the activation of signaling pathways that lead to cell growth, proliferation, and differentiation. Despite their significant role in human cancer, the hydrolysis mechanism remains unclear. In the present Letter, we propose a GTP hydrolysis mechanism in which the ? phosphate is cut off primarily by magnesium ion. We studied both normal and mutated Ras and the cause of the malfunction of these mutants, compared the effect of Mg2+ and Mn2+. The simulation results are consistent with the experiments and support the new hydrolysis mechanism. This work will benefit both GTPases and ATPases hydrolysis studies.

Lu, Qiang; Nassar, Nicolas; Wang, Jin

2011-11-01

379

Simultaneous pretreatment and enzymatic hydrolysis of forage biomass  

SciTech Connect

Sweet sorghum is an attractive fermentation feedstock because as much as 40% of the dry weight consists of readily femented sugars such as sucrose, glucose and frutose. Cellulose and hemicellulose comprise another 50%. However, if this material is to be used a year-round feedstock for ethanol production, a stable method of storage must be developed to maintain the sugar content. A modified version of the traditional ensiling process is made effective by the addition of cellulolytic/hemicellulolytic enzymes and lactic acid bacteria to freshly chopped sweet sorghum prior to the production of silage. In situ hydrolysis of cellulose and hemicellulose occurs concurrently with the acidic ensiling fementation. By hydolyzing the acetyl groups using acetyl xylan esterase and 3-0-methyl glucuronyl side chains using pectinase from hemicellulose, cellulose becomes accessible to hydrolysis by cellulase, both during in situ ensiling with enzymes and in the simultaneous saccharification and fermentation (SSF) to ethanol.

Henk, L.; Linden, J.C. [Colorado State Univ., Fort Collins, CO (United States)

1993-12-31

380

Novel agents for enzymatic and fungal hydrolysis of stevioside.  

PubMed

A comparative study on the potential of some biological agents to perform the hydrolysis of stevioside was carried out, aiming at establishing an alternative methodology to achieve the aglycon steviol or its rearranged derivative isosteviol, in high yields to be used in the preparation of novel bioactive compounds. Hydrolysis reactions were performed by using filamentous fungi (Aspergillus niger, Rhizopus stolonifer and Rhizopus arrhizus), a yeast (Saccharomyces cerevisiae) and enzymes (pancreatin and lipases PL250 and VFL 8000). Pancreatin showed the best hydrolytic activity, furnishing isosteviol at 93.9% of yield, at pH 4.0, using toluene as a co-solvent. Steviol was produced using both pancreatin at pH 7.0 (20.2% yield) and A. niger at pH 7 (20.8% yield). PMID:24031374

Milagre, H M S; Martins, L R; Takahashi, J A

2009-04-01

381

Simultaneous hydrolysis-esterification of wet microalgal lipid using acid.  

PubMed

This research demonstrated hydrolysis of wet microalgal lipid and esterification of free fatty acid (FFA) using acid in one-step process. The investigation of simultaneous hydrolysis-esterification (SHE) of wet microalgal lipid was conducted by using L27 orthogonal design and the effects of water content, volume of sulphuric acid, volume of methanol, temperature and time on SHE were examined. As a result, water content was found to be the most effective factor. The effects of various parameters on fatty acid methyl ester (FAME) content and equilibrium relation between FAME and FFA were also examined under water content 80%. Equimolar amounts of sulphuric acid and hydrochloric acid showed similar results. This method has great potential in terms of biodiesel production from microalgae since no organic solvents are used. PMID:24080318

Takisawa, Kenji; Kanemoto, Kazuyo; Kartikawati, Muliasari; Kitamura, Yutaka

2013-12-01

382

Modeling and analysis of CaBr{sub 2} hydrolysis.  

SciTech Connect

The main focus of this paper is the modeling, simulation, and analysis of the CaBr{sub 2} hydrolysis reactor stage in the Calcium-Bromine thermochemical water splitting cycle for nuclear hydrogen production. One concept is to use a spray reactor of CaBr{sub 2} into steam. Droplet models were built up in a series of steps that consider various physical phenomena separately, including droplet flow, heat transfer, phase change, and reaction. Given the large heat reservoir contained in a pool of liquid CaBr{sub 2} that allows bubbles to rise easily, using a bubble column for the hydrolysis reaction appears to be a feasible and promising alternative to the spray reactor concept. The two limiting cases of bubble geometry, spherical and spherical-cap, are considered in the modeling. Results for both droplet and bubble modeling with COMSOL are presented together with recommendations for the path forward.

Lottes, S. A.; Lyczkowski, R. W.; Energy Systems

2006-01-01

383

Catalysis of a Flavoenzyme-Mediated Amide Hydrolysis  

SciTech Connect

A new pyrimidine catabolic pathway (the Rut pathway) was recently discovered in Escherichia coli K12. In this pathway, uracil is converted to 3-hydroxypropionate, ammonia, and carbon dioxide. The seven-gene Rut operon is required for this conversion. Here we demonstrate that the flavoenzyme RutA catalyzes the initial uracil ring-opening reaction to give 3-ureidoacrylate. This reaction, while formally a hydrolysis reaction, proceeds by an oxidative mechanism initiated by the addition of a flavin hydroperoxide to the C4 carbonyl. While peroxide-catalyzed amide hydrolysis has chemical precedent, we are not aware of a prior example of analogous chemistry catalyzed by flavin hydroperoxides. This study further illustrates the extraordinary catalytic versatility of the flavin cofactor.

Mukherjee, Tathagata; Zhang, Yang; Abdelwahed, Sameh; Ealick, Steven E.; Begley, Tadhg P. (Cornell); (TAM)

2010-09-13

384

A DFT investigation of methanolysis and hydrolysis of triacetin  

E-print Network

The thermodynamic and kinetic aspects of the methanolysis and hydrolysis reactions of glycerol triacetate or triacetin, a model triacylglycerol compound, were investigated by using Density Functional Theory (DFT) at the B3LYP/6-31++G(d,p) level of calculation. Twelve elementary steps of triacetin methanolysis were studied under acid-catalyzed and base-catalyzed conditions. The mechanism of acid-catalyzed methanolysis reaction which has not been reported yet for any esters was proposed. The effects of substitution, methanolysis/hydrolysis position, solvent and face of nucleophilic attack on the free energy of reaction and activation energy were examined. The prediction confirmed the facile position at the middle position of glycerol observed by NMR techniques. The calculated activation energy and the trends of those factors agree with existing experimental observations in biodiesel production.

Limpanuparb, Taweetham; Tantirungrotechai, Yuthana; 10.1016/j.theochem.2010.05.022

2012-01-01

385

Snapshots of the maltose transporter during ATP hydrolysis  

SciTech Connect

ATP-binding cassette transporters are powered by ATP, but the mechanism by which these transporters hydrolyze ATP is unclear. In this study, four crystal structures of the full-length wild-type maltose transporter, stabilized by adenosine 5{prime}-({beta},{gamma}-imido)triphosphate or ADP in conjunction with phosphate analogs BeF{sub 3}{sup -}, VO{sub 4}{sup 3-}, or AlF{sub 4}{sup -}, were determined to 2.2- to 2.4-{angstrom} resolution. These structures led to the assignment of two enzymatic states during ATP hydrolysis and demonstrate specific functional roles of highly conserved residues in the nucleotide-binding domain, suggesting that ATP-binding cassette transporters catalyze ATP hydrolysis via a general base mechanism.

Oldham, Michael L.; Chen, Jue (Purdue)

2011-12-05

386

Accelerated Hydrolysis of Aspirin Using Alternating Magnetic Fields  

NASA Astrophysics Data System (ADS)

The major problem of current drug-based therapy is selectivity. As in other areas of science, a combined approach might improve the situation decisively. The idea is to use the pro-drug principle together with an alternating magnetic field as physical stimulus, which can be applied in a spatially and temporarily controlled manner. As a proof of principle, the neutral hydrolysis of aspirin in physiological phosphate buffer of pH 7.5 at 40 °C was chosen. The sensor and actuator system is a commercially available gold nanoparticle (NP) suspension which is approved for animal usage, stable in high concentrations and reproducibly available. Applying the alternating magnetic field of a conventional NMR magnet system accelerated the hydrolysis of aspirin in solution.

Reinscheid, Uwe M.

2009-08-01

387

Investigation of the Polymorphs and Hydrolysis of Uranium Trioxide  

SciTech Connect

This work focuses on progress in gaining a better understanding of the polymorphic nature of the UO3-water system, one of several important materials associated with the nuclear fuel cycle. The UO3-water system is complex and has not been fully characterized, even though these species are common throughout the fuel cycle. Powder x-ray diffraction, Raman and fluorescence characterization was performed on polymorphic forms of UO3 and UO3 hydrolysis products for the purpose of developing some predictive capability of estimating process history and utility, e.g. for polymorphic phases of unknown origin. Specifically, we have investigated three industrially relevant production pathways of UO3 and discovered a previously unknown low temperature route to ?-UO3. Pure phases of UO3, hydrolysis products and starting materials were used to establish optical spectroscopic signatures for these compounds.

Sweet, Lucas E.; Blake, Thomas A.; Henager, Charles H.; Hu, Shenyang Y.; Johnson, Timothy J.; Meier, David E.; Peper, Shane M.; Schwantes, Jon M.

2013-04-01

388

[Progress on cellulase and enzymatic hydrolysis of lignocellulosic biomass].  

PubMed

Biofuels and bio-based chemicals from lignocellulosic biomass are sustainable, making them alternatives to petroleum-derived fuels and chemicals to address the challenges of the shortage of crude oil supply and climate change resulted from the overconsumption of petroleum-based products, particularly in China. However, high cost in liberating sugars from lignocellulosic biomass is still the bottleneck of the commercialization of biofuels and bio-based chemicals. In this article, the major components of cellulases and their synergistic role in the hydrolysis of pre-treated biomass is reviewed, followed by how to evaluate the enzymatic hydrolysis. With the elucidation of the underlying mechanism of the conformations of the enzyme molecules and their effectiveness in attacking cellulose substrate, more efficient enzymes are expected to be developed. Using the high production strain Penicillium decumbens, the on-site production of cellulases for cellulose ethanol production is discussed. PMID:20954385

Fang, Xu; Qin, Yuqi; Li, Xuezhi; Wang, Lushan; Wang, Tianhong; Zhu, Mingtian; Qu, Yinbo

2010-07-01

389

Functionality of alkaline cooked corn bran on tortilla texture  

E-print Network

and flexible. A sensory panel found that tortillas containing nixtamalized cereal brans had a strong alkaline flavor and aroma and a blistered surface, with a soft, moist texture. NCB tortillas had the highest overall acceptability scores. Pericarp from...

Guajardo Flores, Sara

2012-06-07

390

Improving the alkaline stability of imidazolium cations by substitution.  

PubMed

Imidazolium cations are promising candidates for preparing anion-exchange membranes because of their good alkaline stability. Substitution of imidazolium cations is an efficient way to improve their alkaline stability. By combining density functional theory calculations with experimental results, it is found that the LUMO energy correlates with the alkaline stability of imidazolium cations. The results indicate that alkyl groups are the most suitable substituents for the N3 position of imidazolium cations, and the LUMO energies of alkyl-substituted imidazolium cations depend on the electron-donating effect and the hyperconjugation effect. Comparing 1,2-dimethylimidazolium cations (1,2-DMIm+) and 1,3-dimethylimidazolium cations (1,3-DMIm+) with the same substituents reveals that the hyperconjugation effect is more significant in influencing the LUMO energy of 1,3-DMIms. This investigation reveals that LUMO energy is a helpful aid in predicting the alkaline stability of imidazolium cations. PMID:25383401

Dong, Huilong; Gu, Fenglou; Li, Min; Lin, Bencai; Si, Zhihong; Hou, Tingjun; Yan, Feng; Lee, Shuit-Tong; Li, Youyong

2014-10-01

391

Hydrolysis and esterification in organically modified alkoxysilanes: A {sup 29}Si NMR investigation of methyltrimethoxysilane  

SciTech Connect

High-resolution {sup 29}Si NMR was used to investigate the acid-catalyzed hydrolysis and esterification reactions of methyltrimethoxysilane (MTMS) in methanol. The INEPT experiment, adapted for spin systems with multiple heteronuclear coupling constants, was used to assign the closely spaced resonances of the MTMS hydrolysis products. Due to the rapid reaction rates, only the pseudoequilibrium concentration distributions for the resulting hydrolysis products could be determined. Models based on thermodynamically statistical distributions, irreversible hydrolysis reactions, and reversible hydrolysis reactions were nearly equally successful in accounting for the concentration distributions over a wide range of H{sub 2}O/Si ratios (R{sub w}) and temperatures. However, preparation of hydrolyzed MTMS in a nonpseudoequilibrium state unequivocally demonstrated the reversibility of hydrolysis reactions on a short time scale. By measuring the extent of reaction of MTMS systems at high water concentrations, the ratio of the hydrolysis to esterification rate constant was determined to be approximately 100. 36 refs., 7 figs.

Alam, T.M.; Assink, R.A.; Loy, D.A. [Sandia National Lab., Albuquerque, NM (United States)] [Sandia National Lab., Albuquerque, NM (United States)

1996-09-01

392

Acid hydrolysis and carbohydrates characterization of coffee pulp  

Microsoft Academic Search

Hydrolysis of coffee pulp with diluted sulfuric acid was studied by keeping boiling temperature with reflux, a liquid to solid ratio of 10:1 and a particle size ? 1.00 mm. Coffee pulp was treated using several acid concentration (C) and retention times (t). The hydrolysates were analyzed for total sugars by phenol-sulfuric acid and HPLC (TSPA and TSHPLC), reducing sugar

G. Urbaneja; J. Ferrer; G. Paez; L. Arenas; G. Colina

1996-01-01

393

Carbohydrase hydrolysis of canola to enhance oil extraction with hexane  

Microsoft Academic Search

Hydrolysis of three canola cultivars with carbohydrase reduced oil extraction time and increased oil yield. The optimum pretreatment\\u000a before hexane extraction of oil was flaking, autoclaving, adjustment to 30% seed moisture including 0.12% enzyme concentration\\u000a (g enzyme protein\\/100 g flakes), and incubation for 12 hr at 50 C, followed by drying to 4% moisture. Hexane extraction was\\u000a enhanced by grinding

K. Sosulski; F. W. Sosulski; E. Coxworth

1988-01-01

394

Endo-exo Synergism in Cellulose Hydrolysis Revisited*  

PubMed Central

Synergistic cooperation of different enzymes is a prerequisite for efficient degradation of cellulose. The conventional mechanistic interpretation of the synergism between randomly acting endoglucanases (EGs) and chain end-specific processive cellobiohydrolases (CBHs) is that EG-generated new chain ends on cellulose surface serve as starting points for CBHs. Here we studied the hydrolysis of bacterial cellulose (BC) by CBH TrCel7A and EG TrCel5A from Trichoderma reesei under both single-turnover and “steady state” conditions. Unaccountable by conventional interpretation, the presence of EG increased the rate constant of TrCel7A-catalyzed hydrolysis of BC in steady state. At optimal enzyme/substrate ratios, the “steady state” rate of synergistic hydrolysis became limited by the velocity of processive movement of TrCel7A on BC. A processivity value of 66 ± 7 cellobiose units measured for TrCel7A on 14C-labeled BC was close to the leveling off degree of polymerization of BC, suggesting that TrCel7A cannot pass through the amorphous regions on BC and stalls. We propose a mechanism of endo-exo synergism whereby the degradation of amorphous regions by EG avoids the stalling of TrCel7A and leads to its accelerated recruitment. Hydrolysis of pretreated wheat straw suggested that this mechanism of synergism is operative also in the degradation of lignocellulose. Although both mechanisms of synergism are used in parallel, the contribution of conventional mechanism is significant only at high enzyme/substrate ratios. PMID:22733813

Jalak, Jürgen; Kurašin, Mihhail; Teugjas, Hele; Väljamäe, Priit

2012-01-01

395

Preparation of icariside II from icariin by enzymatic hydrolysis method.  

PubMed

It has been reported that icariin and icariside II, two flavonoid glycosides coming from herba epimedii, which have a closely structural relationship, show some pharmacological effects such as preventing osteoporosis, cancer and depression. The content of natural icariside II is very low in herba epimedii, but it is the main component in vivo after the administration of herba epimedii. More icariside II can be obtained from icariin by enzymatic hydrolysis method than by traditional isolation method. This study focuses on finding a simple and feasible method to prepare icariside II from icariin by enzymatic hydrolysis, so as to meet the request for further pharmacologic actions study. Icariin was obtained successively with 90% ethanol extraction, isolation on macroporous resin and purification on silica gel chromatography. Enzymatic hydrolysis conditions were tested for the bioconversion of icariin into icariside II by orthogonal array design. The structures of isolated icariin and produced icariside II were identified by UV, IR, ESIMS, (1)H NMR, (13)C NMR, and DEPT spectroscope. Enzymatic hydrolysis experiment showed that icariin could be transformed into icariside II with the action of beta-glucosidase and the optimum reaction conditions were determined as follows: 50 degrees C, 0.2 M disodium hydrogen phosphate and citric acid buffer system (pH6.0), the ratio of icariin/enzyme is 1:1 and reaction time 5 h. By using this enzymatic condition, 95.5 mg icariside II (with the purity of 99.1%) was obtained eventually by transforming 200 mg icariin. PMID:20026390

Xia, Quan; Xu, Dujuan; Huang, Zhaogang; Liu, Jianjun; Wang, Xinqun; Wang, Xiu; Liu, Shangquan

2010-07-01

396

Application of immobilized lipase to hydrolysis of triacylglyceride  

Microsoft Academic Search

Lipase from Candida cylindracea was immobilized by entrapment with photo-crosslinkable resin prepolymers or urethane prepolymers, and by covalent binding or by adsorption to different types of porous inorganic or organic supports. All of the immobilized lipase preparations thus obtained showed some activity for hydrolysis of olive oil. Lipase entrapped with a hydrophobic photo-cross-linkable resin prepolymer exhibited the highest activity, which

Yoshiharu Kimura; Atsuo Tanaka; Kenji Sonomoto; Takuya Nihira; Saburo Fukui

1983-01-01

397

Enzymatic hydrolysis of cellulose and various pretreated wood fractions  

Microsoft Academic Search

Three strains of Trichoderma-Trichoderma reesei C30, Trichoderma reesei QM9414, and Trichoderma species E58-were used to study the enzymatic hydrolysis of pretreated wood substrates. Each of the culture filtrates was incubated with a variety of commercially prepared cellulose substrates and pretreated wood substrates. Solka floc was the most easily degraded commercial cellulose. The enzyme accessibility of steam-exploded samples which has been

J. N. Saddler; H. H. Brownell; L. P. Clermont; N. Levitin

1982-01-01

398

Further studies on the pancreatic hydrolysis of some natural fats  

Microsoft Academic Search

A series of animal and vegetable fats has been subjected to hydrolysis with pancreatic lipase. From the results obtained,\\u000a the triglyceride compositions of the original fats have been calculated by the method previously proposed by Coleman and Fulton.\\u000a \\u000a These compositions show substantial agreement with those obtained by other methods. Similarities and differences between fats\\u000a are shown to be reflections of

M. H. Coleman

1961-01-01

399

Pancreatic lipase hydrolysis of triglycerides by a semimicro technique  

Microsoft Academic Search

Procedures are described for rapid lipase hydrolysis of triglycerides, isolation of the hydrolytic products by TLC and their\\u000a conversion to methyl esters and fatty acid analysis by GLC. The techniques are applicable to a few mg of triglycerides or\\u000a fats. Examples of data obtained with purified triglycerides indicate that the specific action of pancreatic lipase for the\\u000a 1,3 ester groups

F. E. Luddy; R. A. Barford; S. F. Herb; P. Magidman; R. W. Riemenschneider

1964-01-01

400

Alpha radiolysis and other factors affecting hydrolysis of tributyl phosphate  

Microsoft Academic Search

The primary purpose of this study was to identify the principal degradation products produced by Pu(IV) loading in 30% tributyl phosphate\\/dodecane (TBP-DD) solutions and to determine the formation rates of these species as a function of temperature. Experiments were also conducted to evaluate HNOâ hydrolysis of TBP as a function of temperature and to compare the effects resulting from plutonium

M. H. Lloyd; R. L. Fellows

1985-01-01

401

Continuous enzymatic cellulose hydrolysis in a tubular membrane bioreactor  

Microsoft Academic Search

Cellulose hydrolysis by Celluclast 1.5L (Novozymes A\\/S, Denmark) enzyme preparation was studied in a special tubular membrane reactor, where a porous stainless steel filter was covered by a non-woven technical textile layer providing a fine, hairy surface for simultaneous adsorption of both the cellulose particles and the biocatalyst. Solka Floc BW 200 powder and Mavicell pellets were used as substrates

K. Bélafi-Bakó; A. Koutinas; N. Nemestóthy; L. Gubicza; C. Webb

2006-01-01

402

Solvent Extraction of Tc and Cs from Alkaline Nitrate Wastes  

SciTech Connect

This paper summarizes progress at three collaborating US national laboratories on the extraction of the fission products {sup 99}Tc and {sup 137}Cs from alkaline high-level wastes (HLW). Efficient, economical processes for Tc and Cs extraction (SRTALK and alkaline-side CSEX, respectively) have been developed, and testing has progressed through batch tests on actual wastes and continuous countercurrent centrifugal-contactor tests on simulants.

Bonnesen, P.V.; Conner, C.; Delmau, L.H.; Haverlock, T.J.; Leonard, R.A.; Lumetta, G.J.; Moyer, B.A.; Sachleben, R.A.

1999-07-11

403

Variation in serum alkaline phosphatase activity in cattle  

E-print Network

VARIATION IN SERUM ALKALINE PHOSPHATASE ACTIVITY IN CATTLE A DISSERTATION BY JESSE LANE FLETCHER Approved as to style and content by: Co-chairman of Committee ^ r -M . 4 L f t ) Co-chairman of Committee \\ Departmen January 1956 L I B R A... U / A 4 M COLLEGE OF TEXAS VARIATION IN SERUM ALKALINE PHOSPHATASE ACTIVITY IN CATTLE A DISSERTATION BY JESSE LANE FLETCHER Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment...

Fletcher, Jesse Lane

1956-01-01

404

Alkaline peroxide mechanical pulping of wheat straw with enzyme treatment  

Microsoft Academic Search

Alkaline peroxide mechanical pulping (APMP) of wheat straw with enzyme treatment was studied. Instead of direct enzyme pretreatment\\u000a on wheat straw, an alternative treatment method was used, in which coarse pulps from refiner defibrated wheat straw rather\\u000a than wheat straw were pretreated with a crude enzyme containing mainly xylanase, then impregnated with alkaline H2O2 solution and further refined. The optimum

Jian Zhao; Xuezhi Li; Yinbo Qu; Peiji Gao

2004-01-01

405

Spectroscopic studies of alkaline activated slag geopolymers  

NASA Astrophysics Data System (ADS)

In the work, results of structural studies of different geopolymers, obtained using a granulated blast furnace slag, are presented. The slag was subjected to an alkaline activation process. As activators, NaOH, Na 2CO 3 and liquid glass were applied. IR and NMR spectroscopy were the main experimental methods used, the results obtained were compared with XRD phase analysis and SEM observations. In the IR spectra of raw slag as well as in the spectra of products of paste hydration, the bands due to the characteristic vibrations of bonds observed in both types of oxygen bridges: Si-O-Si and Si-O-Al, were assigned. These bridges constitute basic structural units, forming tetrahedral geopolymer chains. It was found that the slag composition, mainly SiO 2/Al 2O 3 ratio and modification in oxides concentration, influences the presence of the bands connected with the phases (mainly C-S-H) formed during the hydration in the IR spectra. Additionally, significant effect of amorphous phases share on the spectra shape was established. 29Si and 27Al MAS-NMR spectra of initial slag geopolymers and pastes provided information concerning coordination of both atoms in the structures. It was revealed that the kind of slag geopolymers and the conditions of paste hydration influence connectedness of silicooxygen tetrahedra and coordination number of aluminium atoms. Based on IR spectra, it was also possible to determine the influence of the activator type, activation time and hydration conditions on the products formed. Significant changes were observed for the bands assigned to vibrations of carbonate and hydroxide groups. The changes were also noticed in the case of bands due to vibrations of silicate and aluminosilicate bonds.

Mozgawa, W.; Deja, J.

2009-04-01

406

Oxygen electrodes for rechargeable alkaline fuel cells  

NASA Technical Reports Server (NTRS)

Electrocatalysts and supports for the positive electrode of moderate temperature single-unit rechargeable alkaline fuel cells are being investigated and developed. Candidate support materials were drawn from transition metal carbides, borides, nitrides and oxides which have high conductivity (greater than 1 ohm/cm). Candidate catalyst materials were selected largely from metal oxides of the form ABO sub x (where A = Pb, Cd, Mn, Ti, Zr, La, Sr, Na, and B = Pt, Pd, Ir, Ru, Ni (Co) which were investigated and/or developed for one function only, O2 reduction or O2 evolution. The electrical conductivity requirement for catalysts may be lower, especially if integrated with a higher conductivity support. All candidate materials of acceptable conductivity are subjected to corrosion testing. Materials that survive chemical testing are examined for electrochemical corrosion activity. For more stringent corrosion testing, and for further evaluation of electrocatalysts (which generally show significant O2 evolution at at 1.4 V), samples are held at 1.6 V or 0.6 V for about 100 hours. The surviving materials are then physically and chemically analyzed for signs of degradation. To evaluate the bifunctional oxygen activity of candidate catalysts, Teflon-bonded electrodes are fabricated and tested in a floating electrode configuration. Many of the experimental materials being studied have required development of a customized electrode fabrication procedure. In advanced development, the goal is to reduce the polarization to about 300 to 350 mV. Approximately six support materials and five catalyst materials were identified to date for further development. The test results will be described.

Swette, L.; Kackley, N.

1989-01-01

407

Treatment of heterotopic ossification through remote ATP hydrolysis.  

PubMed

Heterotopic ossification (HO) is the pathologic development of ectopic bone in soft tissues because of a local or systemic inflammatory insult, such as burn injury or trauma. In HO, mesenchymal stem cells (MSCs) are inappropriately activated to undergo osteogenic differentiation. Through the correlation of in vitro assays and in vivo studies (dorsal scald burn with Achilles tenotomy), we have shown that burn injury enhances the osteogenic potential of MSCs and causes ectopic endochondral heterotopic bone formation and functional contractures through bone morphogenetic protein-mediated canonical SMAD signaling. We further demonstrated a prevention strategy for HO through adenosine triphosphate (ATP) hydrolysis at the burn site using apyrase. Burn site apyrase treatment decreased ATP, increased adenosine 3',5'-monophosphate, and decreased phosphorylation of SMAD1/5/8 in MSCs in vitro. This ATP hydrolysis also decreased HO formation and mitigated functional impairment in vivo. Similarly, selective inhibition of SMAD1/5/8 phosphorylation with LDN-193189 decreased HO formation and increased range of motion at the injury site in our burn model in vivo. Our results suggest that burn injury-exacerbated HO formation can be treated through therapeutics that target burn site ATP hydrolysis and modulation of SMAD1/5/8 phosphorylation. PMID:25253675

Peterson, Jonathan R; De La Rosa, Sara; Eboda, Oluwatobi; Cilwa, Katherine E; Agarwal, Shailesh; Buchman, Steven R; Cederna, Paul S; Xi, Chuanwu; Morris, Michael D; Herndon, David N; Xiao, Wenzhong; Tompkins, Ronald G; Krebsbach, Paul H; Wang, Stewart C; Levi, Benjamin

2014-09-24

408

Enzymatic hydrolysis of defatted mackerel protein with low bitter taste  

NASA Astrophysics Data System (ADS)

Ultrasound-assisted solvent extraction was confirmed as a novel, effective method for separating lipid from mackerel protein, resulting in a degreasing rate (DR) of 95% and a nitrogen recovery (NR) of 88.6%. To obtain protein hydrolysates with high nitrogen recovery and low bitter taste, enzymatic hydrolysis was performed using eight commercially available proteases. It turned out that the optimum enzyme was the `Mixed enzymes for animal proteolysis'. An enzyme dosage of 4%, a temperature of 50°, and a hydrolysis time of 300 min were found to be the optimum conditions to obtain high NR (84.28%) and degree of hydrolysis (DH, 16.18%) by orthogonal experiments. Glutamic acid was the most abundant amino acid of MDP (defatted mackerel protein) and MDPH (defatted mackerel protein hydrolysates). Compared with the FAO/WHO reference protein, the essential amino acid chemical scores (CS) were greater than 1.0 (1.0-1.7) in MDPH, which is reflective of high nutritional value. This, coupled with the light color and slight fishy odor, indicates that MDPH would potentially have a wide range of applications such as nutritional additives, functional ingredients, and so on.

Hou, Hu; Li, Bafang; Zhao, Xue

2011-03-01

409

Obtaining antimicrobial peptides by controlled peptic hydrolysis of bovine hemoglobin.  

PubMed

Under standard conditions, the peptides and specially the active peptides were obtained from either the denatured hemoglobin that all structures are completely modified or either the native hemoglobin where all structures are intact. In these conditions, antibacterial peptides were isolated from a very complex peptidic hydrolysate which contains more than one hundred peptides having various sizes and characteristics, involving a complex purification process. The new hydrolysis conditions were obtained by using 40% methanol, 30% ethanol, 20% propanol or 10% butanol. These conditions, where only the secondary structure of hemoglobin retains intact, were followed in order to enrich the hydrolyzed hemoglobin by active peptides or obtain new antibacterial peptides. In these controlled peptic hydrolysis of hemoglobin, a selective and restrictive hydrolysate contained only 29 peptides was obtained. 26 peptides have an antibacterial activity against Micrococcus luteus, Listeria innocua, and Escherichia coli with MIC from 187.1 to 1 ?M. Among these peptides, 13 new antibacterial peptides are obtained only in these new hydrolysis conditions. PMID:21510973

Adje, Estelle Yaba; Balti, Rafik; Kouach, Mostafa; Dhulster, Pascal; Guillochon, Didier; Nedjar-Arroume, Naïma

2011-08-01

410

Fatty Acid hydrolysis of acyl marinobactin siderophores by marinobacter acylases.  

PubMed

The marine bacteria Marinobacter sp. DS40M6 and Marinobacter nanhaiticus D15-8W produce a suite of acyl peptidic marinobactin siderophores to acquire iron under iron-limiting conditions. During late-log phase growth, the marinobactins are hydrolyzed to form the marinobactin headgroup with release of the corresponding fatty acid tail. The bntA gene, a homologue of the Pseudomonas aeruginosa pyoverdine acylase gene, pvdQ, was identified from Marinobacter sp. DS40M6. A bntA knockout mutant of Marinobacter sp. DS40M6 produced the suite of acyl marinobactins A-E, without the usual formation of the marinobactin headgroup. Another marinobactin-producing species, M. nanhaiticus D15-8W, is predicted to have two pvdQ homologues, mhtA and mhtB. MhtA and MhtB have 67% identical amino acid sequences. MhtA catalyzes hydrolysis of the apo-marinobactin siderophores as well as the quorum sensing signaling molecule, dodecanoyl-homoserine lactone. In contrast to hydrolysis of the suite of apo-marinobactins by MhtA, hydrolysis of the iron(III)-bound marinobactins was not observed. PMID:25588131

Kem, Michelle P; Naka, Hiroaki; Iinishi, Akira; Haygood, Margo G; Butler, Alison

2015-01-27

411

A single molecule study of cellulase hydrolysis of crystalline cellulose  

NASA Astrophysics Data System (ADS)

Cellobiohydrolase-I (CBH I), a processive exoglucanase secreted by Trichoderma reesei, is one of the key enzyme components in a commercial cellulase mixture currently used for processing biomass to biofuels. CBH I contains a family 7 glycoside hydrolase catalytic module, a family 1 carbohydrate-binding module (CBM), and a highlyglycosylated linker peptide. It has been proposed that the CBH I cellulase initiates the hydrolysis from the reducing end of one cellulose chain and successively cleaves alternate ?-1,4-glycosidic bonds to release cellobiose as its principal end product. The role each module of CBH I plays in the processive hydrolysis of crystalline cellulose has yet to be convincingly elucidated. In this report, we use a single-molecule approach that combines optical (Total Internal Reflection Fluorescence microscopy, or TIRF-M) and non-optical (Atomic Force Microscopy, or AFM) imaging techniques to analyze the molecular motion of CBM tagged with green fluorescence protein (GFP), and to investigate the surface structure of crystalline cellulose and changes made in the structure by CBM and CBH I. The preliminary results have revealed a confined nanometer-scale movement of the TrCBM1-GFP bound to cellulose, and decreases in cellulose crystal size as well as increases in surface roughness during CBH I hydrolysis of crystalline cellulose.

Liu, Yu-San; Luo, Yonghua; Baker, John O.; Zeng, Yining; Himmel, Michael E.; Smith, Steve; Ding, Shi-You

2010-02-01

412

ATP hydrolysis stimulates large length fluctuations in single actin filaments  

E-print Network

Polymerization dynamics of single actin filaments is investigated theoretically using a stochastic model that takes into account the hydrolysis of ATP-actin subunits, the geometry of actin filament tips, the lateral interactions between the monomers as well as the processes at both ends of the polymer. Exact analytical expressions are obtained for a mean growth velocity and for dispersion in length fluctuations. It is found that the ATP hydrolysis has a strong effect on dynamic properties of single actin filaments. At high concentrations of free actin monomers the mean size of unhydrolyzed ATP-cap is very large, and the dynamics is governed by association/dissociation of ATP-actin subunits. However, at low concentrations the size of the cap becomes finite, and the dissociation of ADP-actin subunits makes a significant contribution to overall dynamics. Actin filament length fluctuations reach the maximum at the boundary between two dynamic regimes, and this boundary is always larger than the critical concentration. Random and vectorial mechanisms of hydrolysis are compared, and it is found that they predict qualitatively similar dynamic properties. The possibility of attachment and detachment of oligomers is also discussed. Our theoretical approach is successfully applied to analyze the latest experiments on the growth and length fluctuations of individual actin filaments.

Evgeny B. Stukalin; Anatoly B. Kolomeisky

2005-07-27

413

Hydrolysis of organonitrate functional groups in aerosol particles  

SciTech Connect

Organonitrate (ON) groups are important substituents in secondary organic aerosols. Model simulations and laboratory studies indicate a large fraction of ON groups in aerosol particles, but much lower quantities are observed in the atmosphere. Hydrolysis of ON groups in aerosol particles has been proposed recently. To test this hypothesis, we simulated formation of ON molecules in a reaction chamber under a wide range of relative humidity (0% to 90%). The mass fraction of ON groups (5% to 20% for high-NOx experiments) consistently decreased with increasing relative humidity, which was best explained by hydrolysis of ON groups at a rate of 4 day-1 (lifetime of 6 hours) for reactions under relative humidity greater than 20%. In addition, we found that secondary nitrogen-containing molecules absorb light, with greater absorption under dry and high-NOx conditions. This work provides the first evidence for particle-phase hydrolysis of ON groups, a process that could substantially reduce ON group concentration in the atmosphere.

Liu, Shang; Shilling, John E.; Song, Chen; Hiranuma, Naruki; Zaveri, Rahul A.; Russell, Lynn M.

2012-10-19

414

Hydrolysis of whey protein isolate using subcritical water.  

PubMed

Hydrolyzed whey protein isolate (WPI) is used in the food industry for protein enrichment and modification of functional properties. The purpose of the study was to determine the feasibility of subcritical water hydrolysis (SWH) on WPI and to determine the temperature and reaction time effects on the degree of hydrolysis (DH) and the production of peptides and free amino acids (AAs). Effects of temperature (150 to 320 °C) and time (0 to 20 min) were initially studied with a central composite rotatable design followed by a completely randomized factorial design with temperature (250 and 300 °C) and time (0 to 50 min) as factors. SWH was conducted in an electrically heated, 100-mL batch, high pressure vessel. The DH was determined by a spectrophotometric method after derivatization. The peptide molecular weights (MWs) were analyzed by gel electrophoresis and mass spectrometry, and AAs were quantified by high-performance liquid chromotography. An interaction of temperature and time significantly affected the DH and AA concentration. As the DH increased, the accumulation of lower MW peptides also increased following SWH (and above 10% DH, the majority of peptides were <1000 Da). Hydrolysis at 300 °C for 40 min generated the highest total AA concentration, especially of lysine (8.894 mg/g WPI). Therefore, WPI was successfully hydrolyzed by subcritical water, and with adjustment of treatment parameters there is reasonable control of the end-products. PMID:22122092

Espinoza, Ashley D; Morawicki, Rubén O; Hager, Tiffany

2012-01-01

415

Nitrogen isotope evidence for alkaline lakes on late Archean continents  

NASA Astrophysics Data System (ADS)

Nitrogen isotope ratios in ancient sedimentary rocks are generally interpreted as a proxy for metabolic nitrogen pathways and the redox state of the water column. Fractionation processes occurring under anoxic, alkaline conditions during the dissociation of NH4+ to H+ and volatile NH3 are frequently overlooked, although this mechanism imparts large isotopic fractionations. Here we propose that NH3 volatilization is largely responsible for ?15N values of up to + 50 ‰ at high C/N ratios in the late Archean Tumbiana Formation. This sequence of sedimentary rocks represents a system of lakes that formed on subaerial flood basalts and were partly filled by basaltic volcanic ash. Aqueous alteration of volcanic glass followed by evaporative concentration of ions should have led to the development of high alkalinity with a pH of 9 or higher, as in modern analogues. In this sedimentologically unusual setting, nitrogen isotope ratios thus provide indirect evidence for the oldest alkaline lake system in the rock record. These very heavy lacustrine ?15N values contrast markedly with those of Archean marine sedimentary rocks, making a Precambrian "soda ocean" unlikely. Today, alkaline lakes are among the most productive ecosystems on Earth. Some nutrients, in particular molybdenum, are more soluble at high pH, and certain prebiotic reactions would likely have been favored under alkaline conditions in similar settings earlier in Earth's history. Hence alkaline lakes in the Archean could have been significant for the origin and early evolution of life.

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

2015-02-01

416

Cation exchange properties of zeolites in hyper alkaline aqueous media.  

PubMed

Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media. PMID:25569300

Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

2015-02-01

417

Soil Alkalinization and irrigation in the Sahelian zone of Niger II: Agronomic consequences of alkalinity and sodicity  

Microsoft Academic Search

Soils of the terraces of the Niger River have locally undergone, prior to irrigation, a process of alkalinization. The use of the resulting nonsaline sodic soils [pHs 8.5–9.8 (s is “on saturated paste\\

S. Marlet; L. Barbiero; V. Valles

1998-01-01

418

Expression of alkaline phosphatases during embryonic development and immature stages of the earthworm, Eisenia andrei  

Microsoft Academic Search

Expression of alkaline phosphatases in developing embryo and mature stages of the earthworm, Eisenia andrei was investigated. The embryonic stages examined in this study appeared to have only one slow-moving form of alkaline phosphatase which had a different mobility from the intestinal alkaline phosphatases of the mature worm, suggesting that intestinal alkaline phosphatases of embryos may be different from mature

Soon Cheol Park; Hee Woo Park; Timothy J. Smith

1996-01-01

419

Regenerating cellulose from ionic liquids for an accelerated enzymatic hydrolysis  

SciTech Connect

The efficient conversion of lignocellulosic materials into fuel ethanol has become a research priority in producing affordable and renewable energy. The pretreatment of lignocelluloses is known to be key to the fast enzymatic hydrolysis of cellulose. Recently, certain ionic liquids (ILs)were found capable of dissolving more than 10 wt% cellulose. Preliminary investigations [Dadi, A.P., Varanasi, S., Schall, C.A., 2006. Enhancement of cellulose saccharification kinetics using an ionic liquid pretreatment step. Biotechnol. Bioeng. 95, 904 910; Liu, L., Chen, H., 2006. Enzymatic hydrolysis of cellulose materials treated with ionic liquid [BMIM]Cl. Chin. Sci. Bull. 51, 2432 2436; Dadi, A.P., Schall, C.A., Varanasi, S., 2007. Mitigation of cellulose recalcitrance to enzymatic hydrolysis by ionic liquid pretreatment. Appl. Biochem. Biotechnol. 137 140, 407 421] suggest that celluloses regenerated from IL solutions are subject to faster saccharification than untreated substrates. These encouraging results offer the possibility of using ILs as alternative and nonvolatile solvents for cellulose pretreatment. However, these studies are limited to two chloride-based ILs: (a) 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), which is a corrosive, toxic and extremely hygroscopic solid (m.p. 70 C), and (b) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl), which is viscous and has a reactive side-chain. Therefore, more in-depth research involving other ILs is much needed to explore this promising pretreatment route. For this reason, we studied a number of chloride- and acetate-based ILs for cellulose regeneration, including several ILs newly developed in our laboratory. This will enable us to select inexpensive, efficient and environmentally benign solvents for processing cellulosic biomass. Our data confirm that all regenerated celluloses are less crystalline (58 75% lower) and more accessible to cellulase (>2 times) than untreated substrates. As a result, regenerated Avicel cellulose, filter paper and cottonwere hydrolyzed 2 10 times faster than the respective untreated celluloses. A complete hydrolysis of Avicel cellulose could be achieved in 6 h given the Trichoderma reesei cellulase/substrate ratio (w/w) of 3:20 at 50 C. In addition,we observed that cellulase is more thermally stable (up to 60 C) in the presence of regenerated cellulose. Furthermore, our systematic studies suggest that the presence of various ILs during the hydrolysis induced different degrees of cellulase inactivation. Therefore, a thorough removal of IL residues after cellulose regeneration is highly recommended, and a systematic investigation on this subject is much needed.

Zhao, Hua [Savannah State University; Jones, Cecil L [Savannah State University; Baker, Gary A [ORNL; Xia, Shuqian [Tianjin University, Tianjin, China; Olubajo, Olarongbe [Savannah State University; Person, Vernecia [Savannah State University

2009-01-01

420

Pretreatment and enzymatic hydrolysis of recovered fibre for ethanol production.  

PubMed

Recovered fibre from pulp mills represents a potentially significant feedstock for conversion to ethanol. Enzymatic hydrolysis of untreated recovered fibre (86.5 Kappa, 13% lignin) resulted in a hexose yield of approximately 23%, which highlighted the need for an effective pretreatment. Recovered fibre was pretreated as a substrate for enzymatic hydrolysis using oxygen delignification. An experimental design was used to optimize temperature (90-150 degrees C), caustic loading (2-10%), and reaction time (20-60 min). The post-delignification Kappa values ranged from 76.7 (11.5% lignin) under the mildest pretreatment conditions, to 20 (3% lignin) under the most severe pretreatment conditions. The effect of caustic load appears to have an increased effect at higher temperatures, with the Kappa numbers ranging from 76.7 (90 degrees C, 2% caustic, 20 min) to 56.0 (150 degrees C, 2% caustic, 20 min) and from 64.7 (90 degrees C, 10% caustic, 20 min) to 38.0 (150 degrees C, 10% caustic, 60 min). These changes in Kappa number reflect changes in the lignin fraction of 3.1% and 4%, respectively. Increasing the caustic load from 2% to 10% decreased the oxygen delignification yield from 93.5% to 87.9% at 90 degrees C and 20 min reaction time, and 80.3% to 74.7% at 150 degrees C. The effect of time on oxygen delignification yield was found to be most significant in the first twenty minutes, which correlates with the drop in Kappa number that was observed. The pretreated fibre was subjected to enzymatic hydrolysis using commercial enzymes Celluclast (80FPU/mL, 20.1CBU/mL) and Novozym (640.5 CBU/mL). A series of enzyme loadings ranging from 19 to 77 FPU/g were utilized on solids loading ranging from 20 to 100g (dry fibre)/L. Based on the pretreatment and hydrolysis results an empirical model was developed that can predict hydrolysis sugar concentrations based on the Kappa number, enzyme loading, and initial recovered fibre concentration. PMID:20006493

Ruffell, John; Levie, Benjamin; Helle, Steve; Duff, Sheldon

2010-04-01

421

Theoretical Study of Acid-Catalyzed Hydrolysis of Epoxides Raimundo Clecio Dantas Muniz Filho, Samuel Anderson Alves de Sousa,  

E-print Network

Theoretical Study of Acid-Catalyzed Hydrolysis of Epoxides Raimundo Clecio Dantas Muniz Filho A theoretical study of propylene oxide acid-catalyzed hydrolysis was performed by investigation of the SN1 in biological and industrial applications is its hydrolysis.5 From the biological point of view, the hydrolysis

Ferreira, Márcia M. C.

422

Factors affecting hydrolysis of condensed phosphates in soils  

E-print Network

soils than in soils at field capacity. In contrast, Giordano and Mortvedt (1978) found that varying soil moisture levels had relatively little effect on P uptake and dry matter yields of corn. However, flooded conditions were not employed... (1975), employing corn as the test crop with 30C days and 20C nights, found that in a slightly acid soil both OP and polyphosphate effectively supplied P for plant growth, while in an alkaline-calcareous soil polyphosphate was significantly less...

Stewart, William M.

2012-06-07

423

Ultrasound-accelerated enzymatic hydrolysis of solid leather waste  

Microsoft Academic Search

The leather industry is a heavy pollution industry and looking for clean technology. The utilization of enzyme and ultrasound in the industry are potential eco-friendly technologies.Enzymes can degrade the untanned solid leather waste. According to our investigation, ultrasound (40kHz, 0.64W\\/cm2) has little effect on the activity of one alkaline protease from Bacillus licheniformis. It is the first time to use

Song Jian; Tao Wenyi; Chen Wuyong

2008-01-01

424

Ca12InC13-x and Ba12InC18H4: Alkaline-Earth Indium Allenylides Synthesized in AE/Li Flux (AE = Ca, Ba).  

PubMed

Two new complex main-group metal carbides were synthesized from reactions of indium, carbon, and a metal hydride in metal flux mixtures of an alkaline earth (AE = Ca, Ba) and lithium. Ca12InC13-x and Ba12InC18H4 both crystallize in cubic space group Im3? [a = 9.6055(8) and 11.1447(7) Å, respectively]. Their related structures are both built on a body-centered-cubic array of icosahedral clusters comprised of an indium atom and 12 surrounding alkaline-earth cations; these clusters are connected by bridging monatomic anions (either H(-) or C(4-)) and allenylide anions, C3(4-). The allenylide anions were characterized by Raman spectroscopy and hydrolysis studies. Density of states and crystal orbital Hamilton population calculations confirm that both compounds are metallic. PMID:25375309

Blankenship, Trevor V; Dickman, Matthew J; van de Burgt, Lambertus J; Latturner, Susan E

2015-02-01

425

Compound- and enzyme-specific phosphodiester hydrolysis mechanisms revealed by ?18O of dissolved inorganic phosphate: Implications for marine P cycling  

NASA Astrophysics Data System (ADS)

We have studied the oxygen isotope signature of inorganic phosphate (P i) generated by hydrolysis of nucleic acid phosphodiester (P-diester) compounds by cell-free enzymes (Deoxyribonuclease 1, Phosphodiesterase 1, Alkaline phosphatase) and microbial cultures at natural isotopic abundances. We demonstrate that the diesterase-catalyzed hydrolytic step leads to incorporation of at least one water O into released P i for a total of two O atoms from water incorporated into P i released from P-diesters. In the presence of Phosphodiesterase 1, 16O is preferentially incorporated into nucleotides released from DNA; whereas 18O is preferentially incorporated into nucleotides released from RNA. A strong consistency between predicted O-isotope regeneration signatures based on results of cell-free enzyme experiments and measured isotopic signatures from independent experiments with E. coli cultures was observed and confirms proposed models for phosphoester hydrolysis. Results from these studies made at natural 18O abundance levels provide a new tool, enzyme-specific O-isotope fractionation, for investigations of organophosphate metabolism and phosphorus cycling pathways in natural aquatic systems.

Liang, Yuhong; Blake, Ruth E.

2009-07-01

426

The effect of extracellular polysaccharides on the goethite-surface promoted hydrolysis of organophosphates.  

NASA Astrophysics Data System (ADS)

Organophosphate monoesters comprise a significant fraction of phosphate in soils. In order to access phosphorus needed for growth, plants and microorganisms often require the hydrolysis of large organophosphate molecules. This hydrolysis can be enzymatic or a reaction promoted by contact with an environmental surface. Because phosphorus strongly adsorbs to environmental particles, the fate and transport of phosphorus in the biosphere can be significantly impacted by reactions at the surfaces of these particles. Soil minerals, including the common Fe(III) mineral goethite, have been shown to increase the rate of hydrolysis of organophosphates by acting as catalysts. Many enzyme-secreting microbes and plants can also release extracellular polysaccharides (EPS) into their local environments. EPS is known to adsorb to environmental particles, including goethite. The adsorption of EPS may alter the physico-chemistry of the mineral-phosphate-enzyme system by impacting either the adsorption or enzymatic hydrolysis of organophosphate. Currently, there is little information available regarding the ability of EPS to enhance or inhibit the availability of essential nutrients, such as phosphate, in the environment. In this study we have investigated the hydrolysis of the phosphate monoesters, glucose phosphate (GP) and p-nitrophenyl phosphate (pNPP). To investigate the hydrolysis mechanisms and extent of hydrolysis of phosphate monoesters we studied three systems: 1) abiotic hydrolysis, where monoesters are adsorbed on goethite surfaces; 2) enzymatic hydrolysis where the monoesters are adsorbed to goethite then exposed to an enzyme; and 3) testing whether the presence of alginate, which is used as a model for EPS, can inhibit or enhance the abiotic or enzymatic hydrolysis. To investigate this we used infrared spectroscopy and the ATR sampling technique. Abiotic hydrolysis was examined using goethite as the environmental surface. Adsorption of each monoester to the goethite was found to be rapid, and the subsequent hydrolysis was found to be dependent upon pH and the properties of the mineral-water interface. When enzyme was added to the goethite-monoester system, at the optimum conditions for the acid phosphatase enzyme, the rate of hydrolysis reached nearly the same rate as the enzymatic hydrolysis of the monoester in a goethite-free system. Thus, the enzyme can change the system from one with no hydrolysis to one with significant hydrolysis. The presence of alginate in the goethite-monoester-enzyme system changes the properties of the interface, thereby changing the hydrolysis of these phosphate monoesters.

Kenney, J. P. L.; Olsson, R.; Giesler, R.; Persson, P.

2012-04-01

427

The influence of solid/liquid separation techniques on the sugar yield in two-step dilute acid hydrolysis of softwood followed by enzymatic hydrolysis  

PubMed Central

Background Two-step dilute acid hydrolysis of softwood, either as a stand-alone process or as pretreatment before enzymatic hydrolysis, is considered to result in higher sugar yields than one-step acid hydrolysis. However, this requires removal of the liquid between the two steps. In an industrial process, filtration and washing of the material between the two steps is difficult, as it should be performed at high pressure to reduce energy demand. Moreover, the application of pressure leads to more compact solids, which may affect subsequent processing steps. This study was carried out to investigate the influence of pressing the biomass, in combination with the effects of not washing the material, on the sugar yield obtained from two-step dilute acid hydrolysis, with and without subsequent enzymatic digestion of the solids. Results Washing the material between the two acid hydrolysis steps, followed by enzymatic digestion, resulted in recovery of 96% of the mannose and 81% of the glucose (% of the theoretical) in the liquid fraction, regardless of the choice of dewatering method (pressing or vacuum filtration). Not washing the solids between the two acid hydrolysis steps led to elevated acidity of the remaining solids during the second hydrolysis step, which resulted in lower yields of mannose, 85% and 74% of the theoretical, for the pressed and vacuum-filtered slurry, respectively, due to sugar degradation. However, this increase in acidity resulted in a higher glucose yield (94.2%) from pressed slurry than from filtered slurry (77.6%). Conclusion Pressing the washed material between the two acid hydrolysis steps had no significant negative effect on the sugar yields of the second acid hydrolysis step or on enzymatic hydrolysis. Not washing the material resulted in a harsher second acid hydrolysis step, which caused greater degradation of the sugars during subsequent acid hydrolysis of the solids, particularly in case of the vacuum-filtered solids. However, pressing in combination with not washing the material between the two steps enhanced the sugar yield of the enzymatic digestion step. Hence, it is suggested that the unwashed slurry be pressed to as high a dry matter content as possible between the two acid hydrolysis stages in order to achieve high final sugar yields. PMID:19291286

Monavari, Sanam; Galbe, Mats; Zacchi, Guido

2009-01-01

428

Field measurement of alkalinity and pH  

USGS Publications Warehouse

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

Barnes, Ivan

1964-01-01

429

Investigating Mechanisms of Alkalinization for Reducing Primary Breast Tumor Invasion  

PubMed Central

The extracellular pH (pHe) of many solid tumors is acidic as a result of glycolytic metabolism and poor perfusion. Acidity promotes invasion and enhances metastatic potential. Tumor acidity can be buffered by systemic administration of an alkaline agent such as sodium bicarbonate. Tumor-bearing mice maintained on sodium bicarbonate drinking water exhibit fewer metastases and survive longer than untreated controls. We predict this effect is due to inhibition of tumor invasion. Reducing tumor invasion should result in fewer circulating tumor cells (CTCs). We report that bicarbonate-treated MDA-MB-231 tumor-bearing mice exhibited significantly lower numbers of CTCs than untreated mice (P < 0.01). Tumor pHe buffering may reduce optimal conditions for enzymes involved in tumor invasion such as cathepsins and matrix metalloproteases (MMPs). To address this, we tested the effect of transient alkalinization on cathepsin and MMP activity using enzyme activatable fluorescence agents in mice bearing MDA-MB-231 mammary xenografts. Transient alkalinization significantly reduced the fluorescent signal of protease-specific activatable agents in vivo (P ? 0.003). Alkalinization, however, did not affect expression of carbonic anhydrase IX (CAIX). The findings suggest a possible mechanism in a live model system for breast cancer where systemic alkalinization slows the rate of invasion. PMID:23936808

Robey, Ian F.; Nesbit, Lance A.

2013-01-01

430

Characterization of Human Bone Alkaline Phosphatase in Pichia Pastoris  

NASA Technical Reports Server (NTRS)

A soluble form of human bone alkaline phosphatase has been expressed in a recombinant strain of the methylotrophic yeast Pichia pastoris. We constructed a plasmid containing cDNA encoding for human bone alkaline phosphatase, with the hydrophobic carboxyl terminal portion deleted. Alkaline phosphatase was secreted into the medium to a level of 32mg/L when cultured in shake flasks, and enzyme activity was 12U/mg, as measured by a spectrophotometric assay. By conversion to a fermentation system, a yield of 880mg/L has been achieved with an enzyme activity of 968U/mg. By gel electrophoresis analysis, it appears that greater than 50% of the total protein in the fermentation media is alkaline phosphatase. Although purification procedures are not yet completely optimized, they are expected to include filtration, ion exchange and affinity chromatography. Our presentation will focus on the purification and crystallization results up to the time of the conference. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

Malone, Christine C.; Ciszak, Eva; Karr, Laurel J.

1999-01-01

431

Actin Disassembly Mediated by Severing, Debranching, and Hydrolysis  

NASA Astrophysics Data System (ADS)

For cells to respond effectively to their environment, the actin cytoskeleton must both assemble and disassemble rapidly in the presence of external cues. A great deal of theory has been focused on assembly, but disassembly has so far received less attention. The talk will describe two theoretical treatments of actin disassembly resulting from debranching, severing, and ATP hydrolysis. 1) The dynamics of in vitro actin polymerization caused by filament branching or severing. Via a combination of stochastic-growth simulation and analytic theory, we show that highly branched structures such as those found near the edges of cells cannot persist in steady state. Early in polymerization, highly branched structures form, but disassemble over time leaving very few branched filaments. This causes an overshoot in light scattering intensity as a function of time. Inclusion of the effects of ATP hydrolysis shows that hydrolysis causes an overshoot in the amount of polymerized actin which can be observed in pyrene fluorescence experiments. 2) The interaction between severing and annealing in disassembling a model lamellipodial actin network. The network is treated as a periodic array of crosslinked actin filaments which sever randomly. The lamellipodial actin density drops abruptly as a function of distance from the membrane in the absence of annealing. When annealing is included, the drop is more gradual, and at a critical value of the annealing rate the thickness becomes infinite. It is shown that lamellipodial disassembly is controlled by two characteristic times: the time that a single subunit remains in the network, and the time that it takes for actin polymerized at the membrane to move to the edge of the lamellipodium.

Carlsson, Anders

2008-03-01

432

Paraoxonase 1 (PON1) status and substrate hydrolysis  

SciTech Connect

Paraoxonase 1 (PON1) hydrolyzes a number of organophosphorus (OP) compounds including insecticides and nerve agents. The in vivo efficacy of PON1 to protect against a specific OP exposure depends on the catalytic efficiency of hydrolysis. The Q192R polymorphism affects the catalytic efficiency of hydrolysis of some substrates and not others. While PON1{sub R192} hydrolyzes paraoxon approximately 9-times as efficiently as PON1{sub Q192}, the efficiency is insufficient to provide in vivo protection against paraoxon/parathion exposure. The two PON1{sub 192} alloforms have nearly equivalent but higher catalytic efficiencies for hydrolyzing diazoxon (DZO) and provide equivalent in vivo protection against DZO exposures. On the other hand, PON1{sub R192} is significantly more efficient in hydrolyzing chlorpyrifos oxon (CPO) than PON1{sub Q192} and provides better protection against CPO exposure. Thus, for some exposures it is only the level of plasma PON1 that is important, whereas for others it is both plasma level and the PON1{sub 192} alloform(s) present in plasma that are important. In no case is the plasma level of PON1 unimportant, provided that the catalytic efficiency is sufficient to protect against the exposure. Two-substrate enzyme assay/analysis protocols that reveal both PON1 plasma levels and PON1{sub 192} phenotype (QQ; QR; RR) are designed to optimize the separation of PON1{sub 192} phenotypes; however, they have not been optimized for evaluating in vivo rates of OP detoxication. This study describes the adaptation of a non-OP, two-substrate determination of PON1 status to the conversion of the PON1 status data to physiologically relevant rates of DZO and CPO detoxication. Conversion factors were generated for rates of hydrolysis of different substrates.

Richter, Rebecca J.; Jarvik, Gail P. [Department of Medicine-Division of Medical Genetics, Box 357720, University of Washington, Seattle, WA 98195-7720 (United States); Department of Genome Sciences, University of Washington, Seattle, WA 98195-7720 (United States); Furlong, Clement E. [Department of Medicine-Division of Medical Genetics, Box 357720, University of Washington, Seattle, WA 98195-7720 (United States); Department of Genome Sciences, University of Washington, Seattle, WA 98195-7720 (United States)], E-mail: clem@u.washington.edu

2009-02-15

433

Hydrolysis of organic esters at the mineral/water interface  

SciTech Connect

Organic esters are widely used as insecticides and are part of many commercial products and industrial processes. When these compounds are released into the environment, they contaminate natural resources. To assess their fate and transport it is important to explore degradation and retainment processes. Numerous previous studies have studied the role of adsorption in lowering pollutant concentration and retarding pollutant migration into soils. However, adsorption at the mineral/water interface also affects the mechanisms of degradation and reaction rates. This dissertation research focuses on the ability of metal oxides to catalyze ester hydrolysis and a reaction mechanism is proposed. Furthermore, the authors studied the role of natural occurring adsorbates on the reaction rates. The oxides used in this study are amorphous silica (SiO[sub 2]), [gamma]-aluminum oxide (Al[sub 2]O[sub 3]), anatase (TiO[sub 2]), and geothite (FeOOH). These either occur naturally, or are similar to naturally occurring surfaces. The capability of such oxides to catalyze ester hydrolysis was studied in batch reactors. The organic compounds investigated were carboxylic acid esters and organophosphate pesticides. The hydrolysis of several esters was catalyzed by the presence of oxide suspensions; the extent of catalysis was dependent on the ester structure, the metal oxide, and solution composition. Results suggest that catalysis for carboxylate esters occurs via a surface chelate formation between the carbonyl oxygen, a second donor group of the ester and the surface metal. The presence of organic co-solvents appears to diminish the catalytic effect. Inhibition of surface catalysis was also observed from specific adsorption of naturally occurring ions onto the oxide surface. Natural organic matter was also observed to influence surface catalysis. This research suggests that mineral surfaces may have a role in abiotic transformations of organic pollutants.

Torrents, A.

1992-01-01

434

Xylan hydrolysis in Populus trichocarpa×P. deltoides and model substrates during hydrothermal pretreatment.  

PubMed

Previous studies defined easy and difficult to hydrolyze fractions of hemicellulose that may result from bonds among cellulose, hemicellulose, and lignin. To understand how such bonds affect hydrolysis, Populus trichocarpa×Populus deltoides, holocellulose isolated from P.trichocarpa×P. deltoides and birchwood xylan were subjected to hydrothermal flow-through pretreatment. Samples were characterized by glycome profiling, HPLC, and UPLC-MS. Glycome profiling revealed steady fragmentation and removal of glycans from solids during hydrolysis. The extent of polysaccharide fragmentation, hydrolysis rate, and total xylose yield were lowest for P.trichocarpa×P. deltoides and greatest for birchwood xylan. Comparison of results from P.trichocarpa×P. deltoides and holocellulose suggested that lignin-carbohydrate complexes reduce hydrolysis rates and limit release of large xylooligomers. Smaller differences between results with holocellulose and birchwood xylan suggest xylan-cellulose hydrogen bonds limited hydrolysis, but to a lesser extent. These findings imply cell wall structure strongly influences hydrolysis. PMID:25545089

Trajano, Heather L; Pattathil, Sivakumar; Tomkins, Bruce A; Tschaplinski, Timothy J; Hahn, Michael G; Van Berkel, Gary J; Wyman, Charles E

2015-03-01

435

An intersubunit signaling network coordinates ATP hydrolysis by m-AAA proteases  

PubMed Central

Summary Ring-shaped AAA+ ATPases control a variety of cellular processes by substrate unfolding and remodeling of macromolecular structures. However, how ATP hydrolysis within AAA+ rings is regulated and coupled to mechanical work is poorly understood. Here, we demonstrate coordinated ATP hydrolysis within m-AAA protease ring complexes, conserved AAA+ machines in the inner membrane of mitochondria. ATP binding to one AAA subunit inhibits ATP hydrolysis by the neighboring subunit leading to coordinated rather than stochastic ATP hydrolysis within the AAA ring. Unbiased genetic screens define an intersubunit signaling pathway involving conserved AAA motifs and reveal an intimate coupling of ATPase activities to central AAA pore loops. Coordinated ATP hydrolysis between adjacent subunits is required for membrane dislocation of substrates but not for substrate processing. These findings provide new insight how AAA+ proteins convert energy derived from ATP hydrolysis into mechanical work. PMID:19748354

Augustin, Steffen; Gerdes, Florian; Lee, Sukyeong; Tsai, Francis T.F.; Langer, Thomas; Tatsuta, Takashi

2009-01-01

436

Enhanced attrition bioreactor for enzyme hydrolysis of cellulosic materials  

DOEpatents

A process for converting cellulosic materials, such as waste paper, into fuels and chemicals, such as sugars and ethanol, utilizing enzymatic hydrolysis of the major carbohydrate of paper: cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. An attritor and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. Additionally, microfiltration, ultrafiltration and reverse osmosis steps are included to further increase reaction efficiency. The resulting sugars are converted to a dilute product in a fluidized-bed bioreactor utilizing a biocatalyst, such as microorganisms. The dilute product is then concentrated and purified.

Scott, Timothy C. (Knoxville, TN); Scott, Charles D. (Oak Ridge, TN); Faison, Brendlyn D. (Knoxville, TN); Davison, Brian H. (Knoxville, TN); Woodward, Jonathan (Oak Ridge, TN)

1997-01-01

437

Hollow-fiber enzyme reactors in cellulose hydrolysis  

SciTech Connect

Immobilized ..beta..-glucosidase from Aspergillus phoenicis has been incorporated into the shell side of hollow-fiber ultrafiltration-membrane cartridges. These cartridge systems served as enzymatic reactors for the hydrolysis of cellobiose and were employed in reaction systems for the saccharification of cellulose. In the latter case a mixture of cellulose and the cellulase enzymes from Trichoderma reesei was circulated through the internal lumens of the hollow fibers. Such systems increase the yield of total sugars produced by enzymatic saccharification of cellulose. The hollow-fiber membranes allowed continuous cellulase enzyme processing and significantly reduced cellulase requirements.

Klei, H.E.; Sundstrom, D.W.; Coughlin, R.W.; Ziolkowski, K.

1981-01-01

438

Enhanced attrition bioreactor for enzyme hydrolysis or cellulosic materials  

DOEpatents

A process for converting cellulosic materials, such as waste paper, into fuels and chemicals, such as sugars and ethanol, utilizing enzymatic hydrolysis of the major carbohydrate of paper: cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. An attritor and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. Additionally, microfiltration, ultrafiltration and reverse osmosis steps are included to further increase reaction efficiency. The resulting sugars are converted to a dilute product in a fluidized-bed bioreactor utilizing a biocatalyst, such as microorganisms. The dilute product is then concentrated and purified.

Scott, Timothy C. (Knoxville, TN); Scott, Charles D. (Oak Ridge, TN); Faison, Brendlyn D. (Knoxville, TN); Davison, Brian H. (Knoxville, TN); Woodward, Jonathan (Oak Ridge, TN)

1996-01-01

439

Enhanced attrition bioreactor for enzyme hydrolysis of cellulosic materials  

DOEpatents

A process is described for converting cellulosic materials, such as waste paper, into fuels and chemicals, such as sugars and ethanol, utilizing enzymatic hydrolysis of the major carbohydrate of paper: cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. An attritor and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. Additionally, microfiltration, ultrafiltration and reverse osmosis steps are included to further increase reaction efficiency. The resulting sugars are converted to a dilute product in a fluidized-bed bioreactor utilizing a biocatalyst, such as microorganisms. The dilute product is then concentrated and purified. 1 fig.

Scott, T.C.; Scott, C.D.; Faison, B.D.; Davison, B.H.; Woodward, J.

1997-06-10

440

Enhanced attrition bioreactor for enzyme hydrolysis or cellulosic materials  

DOEpatents

A process is described for converting cellulosic materials, such as waste paper, into fuels and chemicals, such as sugars and ethanol, utilizing enzymatic hydrolysis of the major carbohydrate of paper: cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. An attritor and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. Additionally, microfiltration, ultrafiltration and reverse osmosis steps are included to further increase reaction efficiency. The resulting sugars are converted to a dilute product in a fluidized-bed bioreactor utilizing a biocatalyst, such as microorganisms. The dilute product is then concentrated and purified. 1 fig.

Scott, T.C.; Scott, C.D.; Faison, B.D.; Davison, B.H.; Woodward, J.

1996-04-16

441

Stability of commercial glucanase and ?-glucosidase preparations under hydrolysis conditions  

PubMed Central

The cost of enzymes makes enzymatic hydrolysis one of the most expensive steps in the production of lignocellulosic ethanol. Diverse studies have used commercial enzyme cocktails assuming that change in total protein concentration during hydrolysis was solely due to adsorption of endo- and exoglucanases onto the substrate. Given the sensitivity of enzymes and proteins to media conditions this assumption was tested by evaluating and modeling the protein concentration of commercial cocktails at hydrolysis conditions. In the absence of solid substrate, the total protein concentration of a mixture of Celluclast 1.5 L and Novozyme 188 decreased by as much as 45% at 50 °C after 4 days. The individual cocktails as well as a mixture of both were stable at 20 °C. At 50 °C, the protein concentration of Celluclast 1.5 was relatively constant but Novozyme 188 decreased by as much as 77%. It was hypothesized that Novozyme 188 proteins suffer a structural change at 50 °C which leads to protein aggregation and precipitation. Lyophilized ?-glucosidase (P-?-glucosidase) at 50 °C exhibited an aggregation rate which was successfully modeled using first order kinetics (R2 = 0.97). By incorporating the possible presence of chaperone proteins in Novozyme 188, the protein aggregation observed for this cocktail was successfully modeled (R2 = 0.96). To accurately model the increasing protein stability observed at high cocktail loadings, the model was modified to include the presence of additives in the cocktail (R2 = 0.98). By combining the measurement of total protein concentration with the proposed Novozyme 188 protein aggregation model, the endo- and exoglucanases concentration in the solid and liquid phases during hydrolysis can be more accurately determined. This methodology can be applied to various systems leading to optimization of enzyme loading by minimizing the excess of endo- and exoglucanases. In addition, the monitoring of endo- and exoglucanases concentrations can be used to build mass balances of enzyme recycling processes and to techno-economically evaluate the viability of enzyme recycling. PMID:24949230

Rosales-Calderon, Oscar; Duff, Sheldon J.B.

2014-01-01

442

Si NMR sensitivity enhancement methods for the quantitative study of organosilicate hydrolysis and condensation  

E-print Network

29 Si NMR sensitivity enhancement methods for the quantitative study of organosilicate hydrolysis condi- tions for efficient silica production [1­7]. The process involves the hydrolysis and subsequent­O­H ! Si­O­Si þ H2O ð2� and Si­O­H þ Si­O­R ! Si­O­Si þ ROH ð3� Thorough characterization of hydrolysis

Sahai, Nita

443

ATP and ADP hydrolysis in brain membranes of zebrafish (Danio rerio)  

E-print Network

ATP and ADP hydrolysis in brain membranes of zebrafish (Danio rerio) Eduardo Pacheco Rico1 , Mario hydrolysis in a pH range of 7.5­8.0 in the presence of Ca2 + (5 mM). The enzyme displayed a maximal activity for ATP and ADP hydrolysis at 37 jC. It was able to hydrolyze purine and pyrimidine nucleosides 5V

Eizirik, Eduardo

444

Hydrolysis and esterification in organically modified alkoxysilanes: A ²⁹Si NMR investigation of methyltrimethoxysilane  

Microsoft Academic Search

High-resolution ²⁹Si NMR was used to investigate the acid-catalyzed hydrolysis and esterification reactions of methyltrimethoxysilane (MTMS) in methanol. The INEPT experiment, adapted for spin systems with multiple heteronuclear coupling constants, was used to assign the closely spaced resonances of the MTMS hydrolysis products. Due to the rapid reaction rates, only the pseudoequilibrium concentration distributions for the resulting hydrolysis products could

Todd M. Alam; Roger A. Assink; Douglas A. Loy

1996-01-01

445

Improvement of the enantioselectivity of lipase-catalyzed naproxen ester hydrolysis in organic solvent  

Microsoft Academic Search

A method is presented to improve the enantioselectivity of lipase-catalyzed hydrolysis of naproxen methyl ester in water-saturated isooctane. It is shown that coupling of the enantioselective hydrolysis of Naproxen methyl ester with the photo-dissociation methanol leads to the photocatalytic conversion of methanol into water, by which the equilibrium constant (K) of the lipase-catalyzed hydrolysis was changed. The equilibrium yield and

Jia-Ying Xin; Shu-Ben Li; Xi-Hui Chen; Lai-Lai Wang; Yi Xu

2000-01-01

446

Alkaline/peracetic acid as a pretreatment of lignocellulosic biomass for ethanol fuel production  

NASA Astrophysics Data System (ADS)

Peracetic acid is a lignin oxidation pretreatment with low energy input by which biomass can be treated in a silo type system for improving enzymatic digestibility of lignocellulosic materials for ethanol production. Experimentally, ground hybrid poplar wood and sugar cane bagasse are placed in plastic bags and a peracetic acid solution is added to the biomass in different concentrations based on oven-dry biomass. The ratio of solution to biomass is 6:1; after initial mixing of the resulting paste, a seven-day storage period at about 20°C is used in this study. As a complementary method, a series of pre-pretreatments using stoichiometric amounts of sodium hydroxide and ammonium hydroxide based on 4-methyl-glucuronic acid and acetyl content in the biomass is been performed before addition of peracetic acid. The alkaline solutions are added to the biomass in a ratio of 14:1 solution to biomass; the slurry is mixed for 24 hours at ambient temperature. The above procedures give high xylan content substrates. Consequently, xylanase/beta-glucosidase combinations are more effective than cellulase preparations in hydrolyzing these materials. The pretreatment effectiveness is evaluated using standard enzymatic hydrolysis and simultaneous saccharification and cofermentation (SSCF) procedures. Hybrid poplar wood pretreated with 15 and 21% peracetic acid based on oven-dry weight of wood gives glucan conversion yields of 76.5 and 98.3%, respectively. Sugar cane bagasse pretreated with the same loadings gives corresponding yields of 85.9 and 93.1%. Raw wood and raw bagasse give corresponding yields of 6.8 and 28.8%, respectively. The combined 6% NaOH/15% peracetic acid pretreatments increase the glucan conversion yields from 76.5 to 100.0% for hybrid poplar wood and from 85.9 to 97.6% for sugar cane bagasse. Respective ethanol yields of 92.8 and 91.9% are obtained from 6% NaOH/15% peracetic acid pretreated materials using recombinant Zymomonas mobilis CP4/pZB5. Peracetic acid pretreatment improves enzymatic digestibility of hybrid poplar wood and sugar cane bagasse. Based on reduction of acetyl groups in the two lignocellulosic materials, alkaline pre-pretreatments are helpful in reducing peracetic acid requirements in the pretreatment and consequently diminishing growth inhibition of the bacteria that was observed using higher peracetic acid loadings.

Teixeira, Lincoln Cambraia

447

Actinide-Aluminate Speciation in Alkaline Radioactive Waste  

SciTech Connect

Investigation of behavior of actinides in alkaline media containing AL(III) showed that no aluminate complexes of actinides in oxidation states (IIII-VIII) were formed in alkaline solutions. At alkaline precipitation IPH (10-14) of actinides in presence of AL(III) formation of aluminate compounds is not observed. However, in precipitates contained actinides (IIV)<(VI), and to a lesser degree actinides (III), some interference of components takes place that is reflected in change of solid phase properties in comparison with pure components or their mechanical mixture. The interference decreases with rise of precipitation PH and at PH 14 is exhibited very feebly. In the case of NP(VII) the individual compound with AL(III) is obtained, however it is not aluminate of neptunium(VII), but neptunate of aluminium(III) similar to neptunates of other metals obtained earlier.

Dr. David L. Clark; Dr. Alexander M. Fedosseev

2001-12-21

448

Silicon Improves Maize Photosynthesis in Saline-Alkaline Soils  

PubMed Central

The research aimed to determine the effects of Si application on photosynthetic characteristics of maize on saline-alkaline soil, including photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (E), and intercellular CO2 concentration (Ci) of maize in the field with five levels (0, 45, 90, 150, and 225?kg·ha?1) of Si supplying. Experimental results showed that the values of Pn, gs, and Ci of maize were significantly enhanced while the values of E of maize were dramatically decreased by certain doses of silicon fertilizers, which meant that Si application with proper doses significantly increased photosynthetic efficiency of maize in different growth stages under stressing environment of saline-alkaline soil. The optimal dose of Si application in this experiment was 150?kg·ha?1?Si. It indicated that increase in maize photosynthesis under saline-alkaline stress took place by Si application with proper doses, which is helpful to improve growth and yield of maize.

Xie, Zhiming; Song, Ri; Shao, Hongbo; Song, Fengbin; Xu, Hongwen; Lu, Yan

2015-01-01

449

Alkaline direct alcohol fuel cells using an anion exchange membrane  

NASA Astrophysics Data System (ADS)

Alkaline direct alcohol fuel cells using an OH-form anion exchange membrane and polyhydric alcohols were studied. A high open circuit voltage of ca. 800 mV was obtained for a cell using Pt-Ru/C (anode) and Pt/C (cathode) at 323 K, which was about 100-200 mV higher than that for a DMFC using Nafion ®. The maximum power densities were in the order of ethylene glycol > glycerol > methanol > erythritol > xylitol. Silver catalysts were used as a cathode catalyst to fabricate alkaline fuel cells, since silver catalyst is almost inactive in the oxidation of polyhydric alcohols. Alkaline direct ethylene glycol fuel cells using silver as a cathode catalyst gave excellent performance because higher concentrations of fuel could be supplied to the anode.

Matsuoka, Koji; Iriyama, Yasutoshi; Abe, Takeshi; Matsuoka, Masao; Ogumi, Zempachi

450

Preparation processes and properties of expanded graphite for alkaline batteries  

NASA Astrophysics Data System (ADS)

Alkaline batteries have been produced by using expanded graphite as cell cathode conductive material. Expanded graphite was obtained by chemical (CI) and electrochemical (EI) intercalation processes and evaluated. Natural graphite was intercalated with H2SO4, washed, expanded, milled and characterized. Milled graphite was added to natural graphite (1:1 ratio) and tested as a conductive cathode material of high performance alkaline cells. Both processes resulted in suitable alkaline battery materials, however, the electrochemically intercalated samples tended to perform better than chemically intercalated did, because of their better textural characteristics. EI samples had better particle preservation and a larger amount of intercalate, which resulted in better expansion, higher porosity and larger specific surface area, and consequently, a better defoliation than that obtained in the milling process of CI samples.

Vieira, F.; Cisneros, I.; Sansiviero, M. T. C.; Miranda, A. M.; Rosa, N. G.; Lima, U. B.; Mohallem, N. D. S.

2006-05-01

451

Simulation of acid hydrolysis of lignocellulosic residues to fermentable sugars for bioethanol production  

NASA Astrophysics Data System (ADS)

The dilute acid hydrolysis of fir sawdust with sulfuric acid was undertaken in a batch reactor system (autoclave). The experimental data and reaction kinetic analysis indicate that this is a potential process for cellulose and hemicelluloses hydrolysis, due to a rapid hydrolysis reaction for acid concentration 0.045 N at 160-180°C. It was found that significant sugar degradation occurred at these conditions. The optimum conditions gave a yield of 38% total fermentable sugars. The kinetics of dilute acid hydrolysis of cellulose and hemicelluloses (polysaccharides) were simulated using four pseudo-kinetic models. The reaction rate constants were calculated in each case.

Sidiras, Dimitris

2012-12-01

452

Developing a unique microbial hydrolysis process for converting lignocellulosic waste into reducing sugars.  

E-print Network

??This thesis attempted to develop a unique microbial hydrolysis process for converting lignocellulosic waste into reducing sugars for subsequent bioethanol or biochemical production. Five specific… (more)

Qi, Wei.

2012-01-01

453

Base hydrolysis kinetics of HMX-based explosives using sodium carbonate  

SciTech Connect

Sodium carbonate has been identified as a possible hydrolysis reagent for decomposing HMX-based explosives to water soluble, non-energetic products. In this study, the reaction kinetics of sodium carbonate hydrolysis are examined and a reaction model is developed. The rate of hydrolysis is reaction rate limited, opposed to mass transfer limited, up to 150{degrees}C. Greater than 99% of the explosive solids in powder form are destroyed in less than 10 minutes at a temperature of 150{degrees}C. The primary products from sodium carbonate hydrolysis are sodium nitrite, formate, nitrate, acetate, glycolate, hexamine, nitrogen gas, nitrous oxide, and ammonia.

Bishop, R.L.; Skidmore, C.; Flesner, R.L.; Dell`orco, P.C.; Spontarelli, T.; Uher, K.J.; Kramer, J.F. [Los Alamos National Lab., NM (United States); Bell, D.A. [Wyoming Univ., Laramie, WY (United States)

1996-07-01

454

Alkalinity production in intertidal sands intensified by lugworm bioirrigation.  

PubMed

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

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

2014-07-01

455

Alkalinity production in intertidal sands intensified by lugworm bioirrigation  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

456

Advanced technology for extended endurance alkaline fuel cells  

NASA Technical Reports Server (NTRS)

Advanced components have been developed for alkaline fuel cells with a view to the satisfaction of NASA Space Station design requirements for extended endurance. The components include a platinum-on-carbon catalyst anode, a potassium titanate-bonded electrolyte matrix, a lightweight graphite electrolyte reservoir plate, a gold-plated nickel-perforated foil electrode substrate, a polyphenylene sulfide cell edge frame material, and a nonmagnesium cooler concept. When incorporated into the alkaline fuel cell unit, these components are expected to yield regenerative operation in a low earth orbit Space Station with a design life greater than 5 years.

Sheibley, D. W.; Martin, R. A.

1987-01-01

457

Heat inactivation of alkaline phosphatase in human milk  

E-print Network

HEAT INAC'"IVATION OF ALKALINE PHOSPHATASE IN HUMAN MILK A Thesis CHINYELU UZOAMAKA ODUMODU Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirement for the degree of MASTER OF SCIE NCE Aug u st 19... 79 Major Subject: Food Science and Technology HEAT 1NACTIVATIGN OF ALKALINE PHGSPHATASE IN HUMAN MILK A Thesi s CHI NYELU UZOAMAKA ODUiMODU Approv as to st e and content by: (Chairman of Committee it td f p t ~t Member) Miemb er August 1979...

Odumodu, Chinyelu Uzoamaka

1979-01-01

458

Alkaline solution absorption of carbon dioxide method and apparatus  

DOEpatents

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

Hobbs, D.T.

1991-01-01

459

Surfactant-enhanced low-pH alkaline flooding  

SciTech Connect

This paper reports sodium bicarbonate investigated as a potential alkaline agent in surfactant-enhanced alkaline flooding because it has very little tendency to dissolve silicate minerals. In experiments performed with Wilmington, CA, crude oil and three types of surfactants, the bicarbonate/surfactant combination caused a marked lowering of interfacial tension (IFT). Bicarbonate protected the surfactant against divalent cations and reduced adsorption of surfactant and polymer on various minerals. Coreflood test confirm that sodium bicarbonate plus surfactant can be an effective alternative to the high-pH flooding process.

Peru, D.A. (Grace (W.R.) and Co., Columbia, MD (USA). Research Div.); Lorenz, P.B. (National Inst. for Petroleum and Energy Research, Bartlesville, OK (USA))

1990-08-01

460

Regulation of intestinal alkaline phosphatase levels in the rat  

PubMed Central

Bilateral adrenalectomy produces a reduction in the alkaline phosphatase concentration in rat intestine, which is not prevented by the administration of saline, but is prevented by the administration of cortisone. The administration of A.C.T.H. to normal rats leads to a rise in intestinal alkaline phosphatase levels associated with a small increase in the weight of the adrenals, while the administration of hydrocortisone produces large increases in the enzyme, even with doses which cause significant hypoplasia of the adrenal glands. The significance of these findings in relation to mechanisms of fat absorption and the treatment of steatorrhoea is discussed. PMID:4301410

Watson, W. C.; Murray, Elspeth S.; Gardner, Mary D.

1967-01-01

461

Heparin modulates adenine nucleotide hydrolysis by synaptosomes from cerebral cortex.  

PubMed

The modulatory effect of heparin and dextran sulfate 500,000 (sulfated polysaccharides) was studied on ATPDase and 5'-nucleotidase activities. These enzymes participate in the degradation of ATP and adenosine production at the synaptic cleft level. Nucleotide hydrolysis was inhibited by heparin and dextran sulfate 500,000. For ADP, the inhibition was more evident at low cation concentrations (0.15 mM Ca2+ or Mg2+), reaching a maximum of 75%. For ATP, the inhibitory effect was less prominent and independent of divalent cation concentration, reaching a maximum of 25%. For AMP, the inhibition observed was similar with either relatively high (1 mM) or with low Mg2+ concentrations tested (0.1 mM) and reached a maximum of 35%. K+ did not change the inhibitory potency of sulfated polysaccharide suggesting that its effects were not exclusively related to charge interaction. These results suggest that heparin and possibly other naturally occurring sulfated polysaccharides may have a potential role as modulator of extracellular nucleotide hydrolysis in the synaptic cleft region. PMID:9759919

Schetinger, M R; Falquembach, F; Michelot, F; Mezzomo, A; Rocha, J B

1998-09-01

462

Aluminum hydrolysis constants to 250°C from boehmite solubility measurements  

NASA Astrophysics Data System (ADS)

Boehmite solubilities were measured at 150, 200, and 250°C at pH values from 1 to 10 at 100 bars total pressure and used to determine the stability constants for the mononuclear aluminum hydroxide complexes (Al(OH) 2+, Al(OH) 2+, Al(OH) 30, Al(OH) 4-),and the solubility product of boehmite. Buffer solutions of HCl-KCl, acetic acid-sodium acetate, sodium bicarbonate-carbonic acid, and boric acid-potassium hydroxide were used to control pH. Our solubility data are in good agreement with boehmite solubility measurements in perchloric acid and sodium hydroxide solutions reported by KUYUNKO et al. (1983). The stability cons