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1

Alkaline thermal sludge hydrolysis.  

PubMed

The waste activated sludge (WAS) treatment of wastewater produces excess sludge which needs further treatment prior to disposal or incineration. A reduction in the amount of excess sludge produced, and the increased dewaterability of the sludge are, therefore, subject of renewed attention and research. A lot of research covers the nature of the sludge solids and associated water. An improved dewaterability requires the disruption of the sludge cell structure. Previous investigations are reviewed in the paper. Thermal hydrolysis is recognized as having the best potential to meet the objectives and acid thermal hydrolysis is most frequently used, despite its serious drawbacks (corrosion, required post-neutralization, solubilization of heavy metals and phosphates, etc.). Alkaline thermal hydrolysis has been studied to a lesser extent, and is the subject of the detailed laboratory-scale research reported in this paper. After assessing the effect of monovalent/divalent cations (respectively, K(+)/Na(+) and Ca(2+)/Mg(2+)) on the sludge dewaterability, only the use of Ca(2+) appears to offer the best solution. The lesser effects of K(+), Na(+) and Mg(2+) confirm previous experimental findings. As a result of the experimental investigations, it can be concluded that alkaline thermal hydrolysis using Ca(OH)(2) is efficient in reducing the residual sludge amounts and in improving the dewaterability. The objectives are fully met at a temperature of 100 degrees C; at a pH approximately 10 and for a 60-min reaction time, where all pathogens are moreover killed. Under these optimum conditions, the rate of mechanical dewatering increases (the capillary suction time (CST) value is decreased from approximately 34s for the initial untreated sample to approximately 22s for the hydrolyzed sludge sample) and the amount of DS to be dewatered is reduced to approximately 60% of the initial untreated amount. The DS-content of the dewatered cake will be increased from 28 (untreated) to 46%.Finally, the mass and energy balances of a wastewater treatment plant with/without advanced sludge treatment (AST) are compared. The data clearly illustrate the benefits of using an alkaline AST-step in the system. PMID:12573845

Neyens, E; Baeyens, J; Creemers, C

2003-02-28

2

Alkaline Hydrolysis of CL-20.  

National Technical Information Service (NTIS)

The Energetics and Warheads Division of the U.S. Army Armament Research, Development and Engineering Center has been involved in the development of CL-20. An alkaline hydrolysis study was performed to better understand the fate and transport of CL-2O thro...

P. Karakaya M. Sidhourn C. Christodoulatos W. Balas S. Nicolich

2005-01-01

3

Alkaline phosphatase revisited: hydrolysis of alkyl phosphates.  

PubMed

Escherichia coli alkaline phosphatase (AP) is the prototypical two metal ion catalyst with two divalent zinc ions bound approximately 4 A apart in the active site. Studies spanning half a century have elucidated many structural and mechanistic features of this enzyme, rendering it an attractive model for investigating the potent catalytic power of bimetallic centers. Unfortunately, fundamental mechanistic features have been obscured by limitations with the standard assays. These assays generate concentrations of inorganic phosphate (P(i)) in excess of its inhibition constant (K(i) approximately 1 muM). This tight binding by P(i) has affected the majority of published kinetic constants. Furthermore, binding limits k(cat)/K(m) for reaction of p-nitrophenyl phosphate, the most commonly employed substrate. We describe a sensitive (32)P-based assay for hydrolysis of alkyl phosphates that avoids the complication of product inhibition. We have revisited basic mechanistic features of AP with these alkyl phosphate substrates. The results suggest that the chemical step for phosphorylation of the enzyme limits k(cat)/K(m). The pH-rate profile and additional results suggest that the serine nucleophile is active in its anionic form and has a pK(a) of < or = 5.5 in the free enzyme. An inactivating pK(a) of 8.0 is observed for binding of both substrates and inhibitors, and we suggest that this corresponds to ionization of a zinc-coordinated water molecule. Counter to previous suggestions, inorganic phosphate dianion appears to bind to the highly charged AP active site at least as strongly as the trianion. The dependence of k(cat)/K(m) on the pK(a) of the leaving group follows a Brønsted correlation with a slope of beta(lg) = -0.85 +/- 0.1, differing substantially from the previously reported value of -0.2 obtained from data with a less sensitive assay. This steep leaving group dependence is consistent with a largely dissociative transition state for AP-catalyzed hydrolysis of phosphate monoesters. The new (32)P-based assay employed herein will facilitate continued dissection of the AP reaction by providing a means to readily follow the chemical step for phosphorylation of the enzyme. PMID:11863460

O'Brien, Patrick J; Herschlag, Daniel

2002-03-01

4

Alkaline Phosphatase Revisited:  Hydrolysis of Alkyl Phosphates †  

Microsoft Academic Search

Escherichia coli alkaline phosphatase (AP) is the prototypical two metal ion catalyst with two divalent zinc ions bound 4 Å apart in the active site. Studies spanning half a century have elucidated many structural and mechanistic features of this enzyme, rendering it an attractive model for investigating the potent catalytic power of bimetallic centers. Unfortunately, fundamental mechanistic features have been

Patrick J. O'Brien; Daniel Herschlag

2002-01-01

5

Alkaline hydrolysis of N-benzoylanthranilic acid  

Microsoft Academic Search

1.The hydrolysis rate of N-benzoylanthranilic acid was studied at a KOH concentration of 2.2–44.6% and a temperature of 25–95°.2.The limiting step of the process is the reaction of the singly ionized form of the reagent with a molecule of water.3.The equilibrium constant for the addition of hydroxyl ion to the carbonyl atom of the amido group of N-benzoylanthranilic acid is

A. Teies Gonsalo; A. I. Donskikh; V. N. Kulagin; Yu. V. Moiseev; G. M. Tseitlin

1976-01-01

6

Stability Patterns of Methoxy Phenols under Alkaline Hydrolysis Conditions  

Microsoft Academic Search

catechol plus their methyl and ethyl analogs, and phenol. The yield of ether-solubles was reported to reach a maximum of about 30% on a weight basis. The yield of identifiable phenolics was about 10% with catechol the largest product (~5%). Thring and co-workers studied the alkaline hydrolysis of lignins isolated with organic solvents, ethylene glycol (7) and ethanol (8). At

D. K. Johnson; J. Salvadób; E. Chornet

7

Alkaline and alkaline peroxide pretreatments at mild temperature to enhance enzymatic hydrolysis of rice hulls and straw.  

PubMed

The current study explores alkaline and alkaline peroxide pretreatments in order to achieve a method to improve saccharification of agricultural residues for ethanol production. The effects of reagent concentration and pretreatment time at 30°C and atmospheric pressure on biomass dissolution after the pretreatment and enzymatic hydrolysis of the pretreated biomass were investigated. In fact, although all pretreatments tested improved enzymatic hydrolysis of native residues, the best results were not achieved for the highest biomass loss. The maximum conversions to reducing sugars in the hydrolysis stage of 77.5% and 92.6% were obtained for rice hulls and straw pretreated by alkaline peroxide (4%, 24h) and alkaline (1%, 48h) methods, respectively. For both pretreated residues, the reduction to more than half the recommended enzyme loading allowed obtaining more than 94% the reducing sugars attained with the recommended dose. PMID:24952164

Cabrera, Emir; Muñoz, María J; Martín, Ricardo; Caro, Ildefonso; Curbelo, Caridad; Díaz, Ana B

2014-09-01

8

The Origins of Phenol Produced in the Rapid Hydrothermolysis and Alkaline Hydrolysis of Hybrid Poplar Lignins  

Microsoft Academic Search

Hybrid poplar lignins were isolated from selected hybrid poplar clones by an enzymatic\\/solvent extraction method. The lignins were subjected to both rapid hydrothermolysis (RHT) and alkaline hydrolysis. Phenol (C6H6OH) was the predominant component of hydrothermolysis products, whilst p-hydroxybenzoic acid (PHBA) was the chief product of the alkaline hydrolysis. Phenol yields were 2–9 wt.% of the lignin, whilst PHBA yields ranged

F. A. Agblevor; D. G. B. Boocock

1989-01-01

9

Mechanisms of lactone hydrolysis in neutral and alkaline conditions.  

PubMed

The neutral and base-catalyzed hydrolysis of nine carboxylic acid esters was studied using a hybrid supermolecule-PCM approach including six explicit water molecules. The molecules studied included two linear esters, four ?-lactones, two ?-lactones, and one ?-lactone: ethyl acetate and methyl formate, ?-propiolactone, ?-butyrolactone, ?-isovalerolactone, diketene (4-methyleneoxetan-2-one), ?-butyrolactone, 2(5H)-furanone, and ?-valerolactone. DFT and ab initio methods were used to analyze the features of the various possible hydrolysis mechanisms. For all compounds, reasonable to very good qualitative and quantitative agreement with experimental work was found, and evidence is provided to support long-standing hypotheses regarding the role of solvent molecule as a base catalyst. In addition, novel evidence is presented for the existence of an elimination-addition mechanism in the basic hydrolysis of diketene. A parallel work addresses the acid-catalyzed hydrolysis of lactones. PMID:23758295

Gómez-Bombarelli, Rafael; Calle, Emilio; Casado, Julio

2013-07-19

10

Susceptibility of a Polycaprolactone-Based Root Canal Filling Material to Degradation. I. Alkaline Hydrolysis  

Microsoft Academic Search

Polycaprolactone, a thermoplastic aliphatic polyester, is reportedly susceptible to both alkaline and enzymatic hydrolyzes. This screening study examined the susceptibility of Resilon, a polycaprolactone-based root filling composite, to alkaline hydrolysis. There were 15-mm diameter disks of Resilon and Obtura gutta-percha prepared by compressive molding and immersed in 20% sodium ethoxide for 20 or 60 min. Control disks were immersed in

Franklin R. Tay; David H. Pashley; M. Chad Williams; Rakesh Raina; Robert J. Loushine; R. Norman Weller; W. Frank Kimbrough; Nigel M. King

2005-01-01

11

Experimental investigation of the kinetics of hydrolysis of sodium borohydride aqueous-alkaline solutions  

NASA Astrophysics Data System (ADS)

Distinctive features of an experimental procedure for determination of the conversion of sodium borohydride in hydrolysis in an aqueous-alkaline medium are described; the procedure is based on measuring the amount of the released hydrogen. Technical and methodological features of implementation of this procedure and measurement errors are discussed; a technique for calculation of the conversion of sodium borohydride in hydrolysis is presented. Experimental data in the form of the constants of a quasistationary hydrolysis regime are given for different isothermal conditions. The range of experiments covers temperatures from 20 to 95°C and alkali concentrations from 10-2 to 5 M.

Nesteruk, A. A.; Kalinin, V. I.; Minkina, V. G.; Martynenko, V. V.; Shabunya, S. I.

2011-09-01

12

Kinetics and mechanism of the alkaline hydrolysis of maleimide.  

PubMed

The kinetics of hydrolysis of maleimide was carried out within the [OH-] range of 2.46 X 10(-6) to 2.0 M at 30 degrees C. The observed pseudo-first-order rate constants, kobs, follow the empirical equation: kobs = (A1[OH-] + A2[OH-]2)/(1 + A3[OH-]). Both ionized and un-ionized forms of maleimide have been suggested to be involved in hydrolysis. The nucleophilic attacks by hydroxide ion at the carbonyl carbon of both ionized and un-ionized maleimide and by water at the carbonyl carbon of ionized maleimide to form tetrahedral intermediates are considered to be the rate-determining steps. The observed results obtained at different 1,4-dioxane-water compositions have revealed an increase in kobs with a decrease in 1,4-dioxane content which could be attributed to the higher polarity of the transition state compared with the reactant state. PMID:6527252

Khan, M N

1984-12-01

13

Aqueous solubility and alkaline hydrolysis of the novel high explosive hexanitrohexaazaisowurtzitane (CL-20).  

PubMed

The recently developed polycyclic nitramine CL-20 is considered as a possible replacement for the monocyclic nitramines RDX and HMX. The present study reports aqueous solubility data for CL-20, as well as the kinetic parameters for its alkaline hydrolysis with sodium hydroxide below and above its solubility limits. Aqueous solubility of CL-20 was measured in the temperature range of 4-69 degrees C and the data were fitted to a generalized solubility model. Alkaline hydrolysis experiments were conducted at 15, 20, 30 and 40 degrees C, with hydroxide concentrations ranging from 0.25 to 300 mM. Like RDX and HMX, alkaline hydrolysis of CL-20 follows second-order kinetics. CL-20 alkaline hydrolysis was found to proceed at a significantly faster rate than RDX. The temperature dependency of the second-order rate constants was evaluated using the Arrhenius model. The activation energy for CL-20 was found to be within close range of the activation energies reported for RDX and HMX. PMID:15811680

Karakaya, Pelin; Sidhoum, Mohammed; Christodoulatos, Christos; Nicolich, Steve; Balas, Wendy

2005-04-11

14

A shrinking core model for the alkaline hydrolysis of PET assisted by tributylhexadecylphosphonium bromide  

Microsoft Academic Search

The kinetics of the alkaline hydrolysis of PET in an aqueous slurry assisted by tributylhexadecylphosphonium bromide as suitable phase transfer catalyst was studied at temperatures ranging from 60 to 80°C. The results were adequately described by an unreacted shrinking core model that was first order with respect to sodium hydroxide concentration, quaternary salt concentration, and particle surface area and, hence,

R. López-Fonseca; J. R. González-Velasco; J. I. Gutiérrez-Ortiz

2009-01-01

15

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 (PO4(3-)-P) and ammonium nitrogen (NH4(+)-N) from the alkaline hydrolysis supernatant of excess sludge. To reduce alkali consumption and decrease the pH of the supernatant, two-stage alkaline hydrolysis process (TSAHP) was designed. The results showed that the release efficiencies of PO4(3-)-P and NH4(+)-N were 41.96% and 7.78%, respectively, and the pH of the supernatant was below 10.5 under the running conditions with initial pH of 13, volume ratio (sludge dosage/water dosage) of 1.75 in second-stage alkaline hydrolysis reactor, 20g/L of sludge concentration in first-stage alkaline hydrolysis reactor. The order of parameters influencing MAP reaction was analyzed and the optimized conditions of MAP reaction were predicted through the response surface methodology. The recovery rates of PO4(3-)-P and NH4(+)-N were 46.88% and 16.54%, respectively under the optimized conditions of Mg/P of 1.8, pH 9.7 and reaction time of 15min. PMID:24880806

Bi, Wei; Li, Yiyong; Hu, Yongyou

2014-08-01

16

Integrating alkaline extraction of proteins with enzymatic hydrolysis of cellulose from wet distiller's grains and solubles.  

PubMed

Fractionation of distiller's grains into value added products may serve to improve the economic viability of dry grind corn ethanol facilities in the wake of variable corn and ethanol prices. This research is aimed at creating a high protein, high lysine product from the grain using alkaline protein extractions in conjunction with hydrolysis of the remaining fiber to sugars which are then fermented to ethanol. Alkaline extractions improved the lysine content in protein products, although protein solubility did not exceed 45% of the total protein. In addition, oligomeric carbohydrates, starch, and other water solubles were also extracted, leading to a low purity protein product. Resulting sugar yields following ammonia fiber expansion (AFEX) pretreatment were also lower for extracted distiller's grains. From these experiments, it does not appear likely that alkaline extraction is a useful tool for fractionation of distiller's grains. However, pretreatment and hydrolysis can be an effective tool for further fractionation of protein. PMID:19620002

Bals, Bryan; Balan, Venkatesh; Dale, Bruce

2009-12-01

17

THE EFFECT OF MIXED MICELLES OF SURFACTANTS ON THE ALKALINE HYDROLYSIS OF ESTERS  

Microsoft Academic Search

The alkaline hydrolysis of aromatic and normal aliphatic acid esters have been studied at 25°C In mixed micellar solution of surfactants (Brij35—SDS, Brij35 — DTAB, Brij35—TTAB.Brij35-CTAB. Triton X—100 —CTAB, Triton X— 100 —SDS) with UV spectrophotometry and the method of thermokinetics The critical mice liar concentrations of the corresponding systems have also been measured with UV spectrophotometry in this paper.

ZENO XIANCHENG; LI QILIN; HE YINGKE; WANG QIAN; QIN ZIMING; LI GUANZUO; HUANG QIZHONG

1996-01-01

18

DFT M06-2X investigation of alkaline hydrolysis of nitroaromatic compounds.  

PubMed

The nitroaromatic compounds 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT) and 2,4-dinitroanisole (DNAN) are potential environmental contaminants and their transformations under a variety of environmental conditions are consequently of great interest. One possible method to safely degrade these nitrocompounds is alkaline hydrolysis. A mechanism of the initial stages of this reaction was investigated computationally. Simulations of UV-VIS and NMR spectra for this mechanism were also produced. The results obtained were compared to available experimental data on the alkaline hydrolysis of TNT and suggest that the formation of Meisenheimer complexes and an anion of TNT are potential first-step intermediates in the reaction path. As the reaction proceeds, computational results indicate that polynegative complexes dominate the degradation pathway, followed by cycles of carbon chain opening and breaking. A second possible pathway was identified that leads to polymeric products through Janovsky complex formation. Results from this study indicate that the order of increasing resistance to alkaline hydrolysis is TNT, DNT and DNAN. PMID:22513338

Hill, Frances C; Sviatenko, Liudmyla K; Gorb, Leonid; Okovytyy, Sergiy I; Blaustein, Gail S; Leszczynski, Jerzy

2012-07-01

19

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

20

Low temperature alkaline pH hydrolysis of oxygen-free Titan tholins  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

21

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

22

Low temperature alkaline pH hydrolysis of oxygen-free Titan tholins  

NASA Astrophysics Data System (ADS)

The largest moon of Saturn, Titan, is known for its dense, nitrogen-rich atmosphere. The organic aerosols which are produced in Titan's atmosphere are of great astrobiological interest, particularly because of their potential evolution when they reach the surface and may interact with putative ammonia-water cryomagma[1]. In this context we have followed the evolution of alkaline pH hydrolysis (25wt% ammonia-water) of Titan tholins (produced by an experimental setup using a plasma DC discharge named PLASMA) at low temperature. Urea has been identified as one of the main product of tholins hydrolysis along with several amino acids (alanine, glycine and aspartic acid). However, those molecules have also been detected in non-hydrolyzed tholins. One explanation is a possible oxygen leak in the PLASMA reactor during the tholins synthesis[2]. Following this preliminary study the synthesis protocol has been improved by isolating the whole device in a specially designed glove box which protect the PLASMA experiment from the laboratory atmosphere. Once we confirmed the non-presence of oxygen in tholins, we performed alkaline pH hydrolysis of oxygen-free tholins. Then we verify that the organic compounds cited above are still produced in-situ. Moreover, a recent study shows that the subsurface ocean may contain a lower fraction of ammonia (about 5wt% or less[3]), than the one used until now in this kind of experimental study[2, 4]. Thus, we have carried out new hydrolysis experiments which take this lower value into account. Additional studies have provided new highlights on the bulk composition of Titan for various gas species. Indeed, the observed Saturn's atmosphere enrichment constrains the composition of the planetesimals present in the feeding zone of Saturn. The enrichment in volatiles in Saturn's atmosphere has been reproduced by assuming the presence of specific gas species[5, 6], in particular CO2 and H2S. In the present study we assume that those gas species have been trapped in the likely internal ocean. Then by taking into account the plausible acid-alkaline properties of the water-ammonia ocean, we determine a new probable composition of the cryomagma which could potentially interact with deposited Titan's aerosols. They were also included in our hydrolysis experiments. Taking into account these new data, four different hydrolyses have been applied to oxygen-free tholins. For each type of hydrolysis, we also follow the influence of the hydrolysis temperature on the organic molecules production. References: [1] Mitri et al., 2008. Resurfacing of Titan by ammonia-water cryomagma. Icarus. 196, 216-224. [2] Poch et al., 2011. Production yields of organics of astrobiological interest from H2O-NH3 hydrolysis of Titan's tholins. Planetary and Space Science. 61, 114-123. [3] Tobie et al. 2012. Titan's Bulk Composition Constrained by Cassini-Huygens: implication for internal outgassing. The Astrophysical Journal. 752, 125. [4] Neish et al., 2009. Low temperature hydrolysis of laboratory tholins in ammonia-water solutions: Implications for prebiotic chemistry on Titan. Icarus. 201, 412-421. [5] Hersant et al., 2004. Enrichment in volatiles in the giant planets of the Solar System. Planetary and Space Science. 52, 623-641. [6] Hersant et al., 2008. Interpretation of the carbon abundance in Saturn measured by Cassini. Planetary and Space Science. 56, 1103-1111. Acknowledgements: We acknowledge support from the French Space Agency (CNES) and the European Space Agency (ESA).

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

2014-05-01

23

Alkaline pretreatment methods followed by acid hydrolysis of Saccharum spontaneum for bioethanol production.  

PubMed

Different alkaline pretreatment methods (NaOH, NaOH+10% urea and aqueous ammonia) were optimized for maximum delignification of Saccharum spontaneum at 30°C. Maximum delignification were obtained as 47.8%, 51% and 48% from NaOH (7% NaOH, 48h, and 10% biomass loading), NaOH+urea (7% NaOH+10% urea, 48 h and 10% biomass loading) and 30% ammonia (40 days and 10% biomass loading) respectively. H(2)SO(4) 60% (v/v), 10% biomass loading at 30°C for 4h, were optimized conditions to solubilize the cellulose and hemicellulose from solid residue obtained after different optimized alkaline pretreatments. Slurry thus obtained was diluted to obtain final acid concentration of 10% (v/v) for real hydrolysis of cellulose and hemicellulose at 100°C for 1h. Among all pretreatment methods applied, the best result 0.58 g (85%) reducing sugars/g of initial biomass after acid hydrolysis was obtained from aqueous ammonia pretreated biomass. Scheffersomyces stipitis CBS6054 was used to ferment the hydrolysate; ethanol yield (Y(p/s)) and productivity (r(p)) were found to be 0.35 g/g and 0.22 g/L/h respectively. PMID:22985852

Chaudhary, Gaurav; Singh, Lalit Kumar; Ghosh, Sanjoy

2012-11-01

24

Ion-exchange chromatography of a dinucleotide preparation from controlled alkaline hydrolysis of ribonucleic acids  

PubMed Central

With the aim of preparing the 16 possible ribodinucleotides derived from the four principal ribonucleotides, we made a kinetic study to determine the optimum conditions for a partial alkaline hydrolysis of RNA. Satisfactory results were obtained when the hydrolysis of RNA (1g.) in 0·2m-sodium hydroxide (100ml.) at 37° was ceased approx. 10min. after the start of the reaction. The relative yields of the monomer, dimer and trimer fractions were approx. 41:30:15 in E260 units, indicating that the reaction conditions were reasonably close to those required from kinetic considerations. The partial alkaline hydrolysate was chromatographed on a column of DEAE-Sephadex A-25 in the presence of 7m-urea. The dinucleotide fraction thus obtained was subjected to a subsequent chromatography on Dowex 1 (X2) under acidic conditions to separate the mixture according to base composition and base sequence. The results were satisfactory, and most of the 32 dinucleotides [i.e. 16 XpYp(3?) plus 16 XpYp(2?)] were fractionated by this single chromatographic procedure. The present method should be useful for further study of oligonucleotides as a time-saving method for the simultaneous preparation of a variety of dinucleotides. Further, examination of the present chromatographic pattern has provided several empirical criteria useful for the identification of oligonucleotides other than dimers appearing in the elution profile of Dowex 1 (X2) column chromatography under similar conditions.

Satoh, Kimihiko; Inoue, Yasuo

1969-01-01

25

Enhanced enzymatic hydrolysis of spruce by alkaline pretreatment at low temperature.  

PubMed

Alkaline pretreatment of spruce at low temperature in both presence and absence of urea was studied. It was found that the enzymatic hydrolysis rate and efficiency can be significantly improved by the pretreatment. At low temperature, the pretreatment chemicals, either NaOH alone or NaOH-urea mixture solution, can slightly remove lignin, hemicelluloses, and cellulose in the lignocellulosic materials, disrupt the connections between hemicelluloses, cellulose, and lignin, and alter the structure of treated biomass to make cellulose more accessible to hydrolysis enzymes. Moreover, the wood fiber bundles could be broken down to small and loose lignocellulosic particles by the chemical treatment. Therefore, the enzymatic hydrolysis efficiency of untreated mechanical fibers can also be remarkably enhanced by NaOH or NaOH/urea solution treatment. The results indicated that, for spruce, up to 70% glucose yield could be obtained for the cold temperature pretreatment (-15 degrees C) using 7% NaOH/12% urea solution, but only 20% and 24% glucose yields were obtained at temperatures of 23 degrees C and 60 degrees C, respectively, when other conditions remained the same. The best condition for the chemical pretreatment regarding this study was 3% NaOH/12% urea, and -15 degrees C. Over 60% glucose conversion was achieved upon this condition. PMID:18023037

Zhao, Yulin; Wang, Ying; Zhu, J Y; Ragauskas, Art; Deng, Yulin

2008-04-15

26

Processing poultry feathers into keratin hydrolysate through alkaline-enzymatic hydrolysis.  

PubMed

Poultry feathers make up for as much as 8.5% of chicken weight and represent a considerable amount of almost pure keratin waste which is not being adequately utilized at the present time. The present study dealt with the processing of poultry feathers through a two-stage alkaline-enzymatic hydrolysis. In the first stage, feathers were mixed with a 0.1 or 0.3% KOH water solution in a 1 : 50 ratio and were incubated at 70°C for 24 h. After adjusting pH to 9, the effects examined in the second processing stage on the amount of degraded feathers were those of proteolytic enzyme additions (1-5%), time (4-8 h) and temperature (50-70°C). Processing feathers in 0.3% KOH and hydrolysing for 8 h in the second stage at 70°C with a 5% dose of enzyme (relative to dry feathers weight) produced approx. 91% degradation. Keratin hydrolysate is distinct for its high nitrogen content and reasonable inorganic solids level. Two-stage technology of alkaline-enzymatic hydrolysing of poultry feathers in an environment of 0.3% KOH achieves high efficiency under quite mild reaction conditions (temperature not exceeding 70°C with pH in a mildly alkaline region), and is feasible from an economic viewpoint. Keratin hydrolysate can find particular application in packaging technology (films, foils and encapsulates). PMID:20483878

Mokrejs, Pavel; Svoboda, Petr; Hrncirik, Josef; Janacova, Dagmar; Vasek, Vladimir

2011-03-01

27

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.

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

2013-01-01

28

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.

2014-01-01

29

Polyphosphate Hydrolysis within Acidic Vacuoles in Response to Amine-Induced Alkaline Stress in the Halotolerant Alga Dunaliella salina.  

PubMed

The location and mobilization of polyphosphates in response to an amine-induced alkaline stress were studied in the halotolerant alga Dunaliella salina. The following observations suggest that polyphosphates accumulate in acidic vacuoles: (a) Accumulation of large amounts of polyphosphates is manifested as intravacuolar dense osmiophilic bodies in electron micrographs. (b) Uptake of amines into the vacuoles induces massive hydrolysis of polyphosphates, demonstrated by in vivo(31)P-nuclear magnetic resonance, and by analysis of hydrolytic products on thin layer chromatograms. The analysis indicates that: (a) Polyphosphate hydrolysis is kinetically correlated with amine accumulation and with the recovery of cytoplasmic pH. (b) The major hydrolytic product is tripolyphosphate. (c) The peak position of the tripolyphosphate terminal phosphate in nuclear magnetic resonance spectra is progressively shifted as the cells recover, indicating that the pH inside the vacuoles increases while the pH in the cytoplasm decreases. (d) In lysed cell preparations, in which vacuoles become exposed to the external pH, mild alkalinization in the absence of amines induces polyphosphate hydrolysis to tripolyphosphates. It is suggested that amine accumulation within vacuoles activates a specific phosphatase, which hydrolyzes long-chain polyphosphates to tripolyphosphates. The hydrolysis increases the capacity of the vacuoles to sequester amines from the cytoplasm probably by releasing protons required to buffer the amine, and leads to recovery of cytoplasmic pH. Thus, polyphosphate hydrolysis provides a high-capacity buffering system that sustains amine compartmentation into vacuoles and protects cytoplasmic pH. PMID:16668514

Pick, U; Weiss, M

1991-11-01

30

Enhanced osteogenic activity of a poly(butylene succinate)/calcium phosphate composite by simple alkaline hydrolysis.  

PubMed

Bone engineering offers the prospect of alternative therapies for clinically relevant skeletal defects. Poly(butylene succinate) (PBSu) is a biodegradable and biocompatible polyester which may possess some limitations in clinical use due to its hydrophobicity. In order to overcome these limitations and increase the bioactivity, a simple and convenient surface hydrolysis of PBSu, PBSu/hydroxyapatite and PBSu/?-tricalcium phosphate (TCP) films was performed. The resulting surfaces (i.e., HPBSu, HPBSu/HA and HPBSu/TCP) were tested for their physicochemical property, biocompatibility and osteogenic potency. The results showed that surface hydrolysis significantly increased surface roughness and hydrophilicity of the composites, with the HPBSu/TCP possessing the most pronounced results. All the materials appeared to be biocompatible and supported in vitro growth and osteoblast differentiation of hMSCs, and the alkaline hydrolysis significantly enhanced the hMSC cell proliferation and the osteogenic potency of PBSu/TCP compared with the non-hydrolyzed sample. In conclusion, the HPBSu/TCP possessed better hydrophilicity, biocompatibility and osteogenic potency in vitro, suggesting that this simple and convenient alkaline hydrolysis could be used to augment the biological property of PBSu-based composites for bone engineering in vivo. PMID:24057872

Arphavasin, Suphakit; Singhatanadgit, Weerachai; Ngamviriyavong, Patcharee; Janvikul, Wanida; Meesap, Preeyapan; Patntirapong, Somying

2013-10-01

31

Enhanced coproduction of hydrogen and methane from cornstalks by a three-stage anaerobic fermentation process integrated with alkaline hydrolysis.  

PubMed

A three-stage anaerobic fermentation process including H(2) fermentation I, H(2) fermentation II, methane fermentation was developed for the coproduction of hydrogen and methane from cornstalks. Hydrogen production from cornstalks using direct microbial conversion by Clostridium thermocellum 7072 was markedly enhanced in the two-stage thermophilic hydrogen fermentation process integrated with alkaline treatment. The highest total hydrogen yield from cornstalks in the two-stage fermentation process reached 74.4 mL/g-cornstalk. The hydrogen fermentation effluents and alkaline hydrolyzate were further used for methane fermentation by anaerobic granular sludge, and the total methane yield reached 205.8 mL/g-cornstalk. The total energy recovery in the three-stage anaerobic fermentation process integrated with alkaline hydrolysis reached 70.0%. PMID:22104098

Cheng, Xi-Yu; Liu, Chun-Zhao

2012-01-01

32

Polyphosphate Hydrolysis within Acidic Vacuoles in Response to Amine-Induced Alkaline Stress in the Halotolerant Alga Dunaliella salina  

PubMed Central

The location and mobilization of polyphosphates in response to an amine-induced alkaline stress were studied in the halotolerant alga Dunaliella salina. The following observations suggest that polyphosphates accumulate in acidic vacuoles: (a) Accumulation of large amounts of polyphosphates is manifested as intravacuolar dense osmiophilic bodies in electron micrographs. (b) Uptake of amines into the vacuoles induces massive hydrolysis of polyphosphates, demonstrated by in vivo 31P-nuclear magnetic resonance, and by analysis of hydrolytic products on thin layer chromatograms. The analysis indicates that: (a) Polyphosphate hydrolysis is kinetically correlated with amine accumulation and with the recovery of cytoplasmic pH. (b) The major hydrolytic product is tripolyphosphate. (c) The peak position of the tripolyphosphate terminal phosphate in nuclear magnetic resonance spectra is progressively shifted as the cells recover, indicating that the pH inside the vacuoles increases while the pH in the cytoplasm decreases. (d) In lysed cell preparations, in which vacuoles become exposed to the external pH, mild alkalinization in the absence of amines induces polyphosphate hydrolysis to tripolyphosphates. It is suggested that amine accumulation within vacuoles activates a specific phosphatase, which hydrolyzes long-chain polyphosphates to tripolyphosphates. The hydrolysis increases the capacity of the vacuoles to sequester amines from the cytoplasm probably by releasing protons required to buffer the amine, and leads to recovery of cytoplasmic pH. Thus, polyphosphate hydrolysis provides a high-capacity buffering system that sustains amine compartmentation into vacuoles and protects cytoplasmic pH. ImagesFigure 1Figure 7

Pick, Uri; Weiss, Meira

1991-01-01

33

Kinetics of the alkaline hydrolysis of 2,4,6-trinitrotoluene in aqueous solution and highly contaminated soils  

SciTech Connect

During the two World Wars, large amounts of TNT were released into the environment. Until today, high concentrations of TNT can be found in the soil of former ammunition plants. To obtain basic data for a novel treatment process for highly contaminated soils, the homogeneous aqueous hydrolysis of TNT in the pH range from 10 to 12 and the alkaline treatment of two contaminated soils at pH 11 and pH 12 were investigated. The experimental data were described for their respective pH values using a pseudo-first-order model. In the homogeneous experiments, 95--97% of the TNT was hydrolyzed. During alkaline hydrolysis, up to two nitrogroups per TNT molecule were released, indicating the irreversible destruction of TNT. Except for the formation of small traces of amino dinitrotoluenes and trinitrobenzenes, no nitroaromatic benzenes or toluenes were detected during GC analysis. For the less contaminated soil, ELBP2, with an initial TNT concentration of 116 mg/kg, a destruction of 99% was achieved. The highly contaminated soil, HTNT2 (16.1 g of TNT/kg), showed a hydrolyzation level of 90-94%. The results show that the alkaline treatment of highly contaminated soils may prove to be effective as an alternative treatment technology.

Emmrich, M.

1999-11-01

34

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

35

Sustainable hydrogen production by catalytic hydrolysis of alkaline sodium borohydride solution using recyclable Co–Co 2B and Ni–Ni 3B nanocomposites  

Microsoft Academic Search

In this article, we report Co–Co2B and Ni–Ni3B nanocomposites as catalyst for hydrogen generation from alkaline sodium borohydride. Kinetic studies of the hydrolysis of sodium borohydride with Co–Co2B and Ni–Ni3B nanocomposites reveal that the concentration of NaBH4 has no effect on the rate of hydrogen generation. Hydrolysis was found to be first order with respect to the concentration of catalyst.

Amit Ashok Vernekar; Sandesh Tukaram Bugde; Santosh Tilve

36

Pretreatment of cane bagasse with alkaline hydrogen peroxide for enzymatic hydrolysis of cellulose and ethanol fermentation  

Microsoft Academic Search

Pretreatment of the agrocellulosic waste, cane bagasse with alkaline hydrogen peroxide greatly enhances its susceptibility to enzymatic cellulolysis and thus the ethanol production from it. Various process conditions have been studied to optimize the enzymate effectiveness. These conditions include the contact time, the hydrogen peroxide concentration and the pretreatment temperature. Results obtained show, that about 50% of lignin and most

A. M. Azzam

1989-01-01

37

Alkaline hydrolysis of dimethyl terephthalate in the presence of [LiAl{sub 2}(OH){sub 6}]Cl.2H{sub 2}O  

SciTech Connect

The alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl{sub 2}(OH){sub 6}]Cl has been investigated to demonstrate a possible application of anion exchange facility of layered double hydroxides (LDHs) to control chemical reactions. The results show that (i) in the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl, most of the interlayer Cl{sup -} of [LiAl{sub 2}(OH){sub 6}]Cl is quickly replaced by OH{sup -} in the alkaline solution because the LDH host favors OH{sup -} more; (ii) the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl is faster than the reaction of DMT and [LiAl{sub 2}(OH){sub 6}]OH; (iii) The hydrolysis of DMT in a buffer solution of pH{approx}8 takes longer time to reach equilibrium than the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl. It is believed that the selective anion exchange chemistry of the LDH plays a key role in storage and controlled release of active reactant, that is, OH{sup -}, thus make the hydrolysis proceeds in a controlled way. - Graphical abstract: XRD patterns of the solid products of the alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl{sub 2}(OH){sub 6}]Cl at 70 deg. C halted at different time, which shows that [LiAl{sub 2}(OH){sub 6}]Cl turns out to be [LiAl{sub 2}(OH){sub 6}]OH, and [LiAl{sub 2}(OH){sub 6}]{sub 2}TP forms gradually. In this reaction, the alkaline hydrolysis of DMT is controlled by replacement of Cl{sup -} in [LiAl{sub 2}(OH){sub 6}]Cl by OH{sup -}, and subsequent replacement of OH{sup -} in [LiAl{sub 2}(OH){sub 6}]OH by terephthalate anion.

Lei Lixu [Department of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096 (China)]. E-mail: lixu.lei@seu.edu.cn1; Zhang Weifeng [Department of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096 (China); Hu Meng [Department of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096 (China); Zheng Hegen [State Key Laboratory of Coordination Chemistry, Nanjing 210093 (China)

2006-11-15

38

Reduction and alkaline hydrolysis of 5-oxoindeno(1,2-b)pyridinium salts  

SciTech Connect

5,9b-dihydro derivatives of indeno(1,2-b)pyridine were obtained by the reduction of the corresponding 1,2-dimethyl-4-acryl-5-oxoindeno(1,2-b)pyridinium perchlorates. 1,2-dimethyl-3-ethoxycarbonyl-4-phenyl-5-oxoindeno(1,2-b)pyridinium perchlorate forms in alkaline medium with splitting, recyclization and deamination products.

Mutsenietse, D.Kh.; Zandersons, A.Z.; Lusis, V.K.; Dubur, G.Ya.

1987-07-01

39

Surface potential and osteoblast attraction to calcium phosphate compounds is affected by selected alkaline hydrolysis processing.  

PubMed

This study examines the link(s) between the suspension behavior of calcium deficient apatites (CDAs) and biphasic calcium phosphate (BCP), as measured by the zeta-potential, with respect to both whole bone and osteoblasts. CDA is fabricated by hydrolyzing an acidic CaP such as dicalcium diphosphate dihydrate (DCPD; CaHPO4.2H2O) and has a structure and composition close to bone apatite. Sintering CDA results in the formation of BCP ceramics consisting of mixtures of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP), with the HA/beta-TCP weight ratio proportional to the Ca/P ratio of CDA. The choice of the base for the DCPD hydrolysis allows various ionic partial substitution of the formed CDA. Na for Ca partial substitution is of interest because of the resulting improvement in mechanical properties of the resulting BCP ceramics and NH4OH was used as a negative control. The zeta-potential was measured for these materials and the stability of the ceramic to bone interaction calculated. zeta-potential values decrease for CDA(NH4OH) versus CDA(NaOH) and increase for BCP(NH4OH) versus BCP(NaOH). While results of these analyses indicate that NH4OH and NaOH processed CDA and BCP will likely yield osteoblast attachment in vivo, differences in the zeta-potentials may explain varying degrees of cell attachment. PMID:15477734

Smith, I O; Baumann, M J; Obadia, L; Bouler, J-M

2004-08-01

40

Synthesis and crystal structure solution of potassium dawsonite: An intermediate compound in the alkaline hydrolysis of calcium aluminate cements  

SciTech Connect

Potassium dawsonite is formed as an intermediate compound during the alkaline hydrolysis (AH) in calcium aluminate cements (CACs). A synthesis method of potassium dawsonite has been developed. The crystal structure of potassium dawsonite KAl(CO{sub 3})(OH){sub 2} has been solved by direct methods from X-ray powder diffraction data and refined with the Rietveld method. It crystallises in the orthorhombic Cmcm space group with unit cells parameters a=6.3021(3) A, b=11.9626(5) A, c=5.6456(3) A and Z=4. The structure consists of carboaluminate chains, formed by the basic unit [Al{sub 2}(OH){sub 4}(CO{sub 3}){sub 2}]{sup 2-} arranged along the c axis. The carbonate groups are placed in an alternate manner at both sides of the carboaluminate chains. The carboaluminate chains are also held together by the K{sup +} cations that are located in the middle of three such chains. Finally, the chemical reactions explaining the AH process in CACs are postulated.

Fernandez-Carrasco, L.; Puertas, F.; Blanco-Varela, M.T.; Vazquez, T.; Rius, J

2005-04-01

41

Alkaline polyol pulping and enzymatic hydrolysis of hardwood: effect of pulping severity and pulp composition on cellulase activity and overall sugar yield.  

PubMed

The saccharification of beech wood using alkaline polyol pulping (AlkaPolP) and enzymatic hydrolysis was investigated. It will be demonstrated that the AlkaPolP process yields high quality pulps which can easily be hydrolyzed by cellulases. In order to find optimum reaction conditions chips of Fagus sylvatica were pretreated by alkaline glycerol at temperatures between 190 and 230 °C for 15, 20, and 25 min. The impacts of temperature and time were expressed using a severity factor R0. The dependencies of the conversion during enzymatic hydrolysis on severity, pulp yield, delignification and pulp composition are shown. In further experiments it was investigated if the sugar yields can be increased by the application of ultrasound or surfactants before enzyme addition. Up to 95% of the initial cellulose in wood were converted into glucose using cellulases from Trichoderma reesei and ?-glucosidase from Aspergillus niger. PMID:23570715

Hundt, Martin; Schnitzlein, Klaus; Schnitzlein, Michael G

2013-05-01

42

Modelling the kinetics of enzyme-catalysed reactions in frozen systems: the alkaline phosphatase catalysed hydrolysis of disodium p-nitrophenyl phosphate  

Microsoft Academic Search

The applicability of the William, Landel and Ferry (WLF) equation with a modification to take into account the effect of melt-dilution and an empirical log-logistic equation were evaluated to model the kinetics of diffusion-controlled reactions in frozen systems. Kinetic data for the alkaline phosphatase catalysed hydrolysis of disodium-p-nitrophenyl phosphate (DNPP) in four model systems with different glass transition temperatures at

Netsanet Shiferaw Terefe; Ann Van Loey; Marc Hendrickx

2004-01-01

43

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

44

Mechanisms and kinetics of alkaline hydrolysis of the energetic nitroaromatic compounds 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN).  

PubMed

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) was 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 intermediate 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. PMID:23373810

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

2013-07-01

45

Combined Alkaline Hydrolysis and Ultrasound-Assisted Extraction for the Release of Nonextractable Phenolics from Cauliflower (Brassica oleracea var. botrytis) Waste.  

PubMed

Cauliflower waste contains high amounts phenolic compounds, but conventional solvent extraction misses high amounts of nonextractable phenolics (NEP), which may contribute more to the valorization of these waste streams. In this study, the NEP content and composition of cauliflower waste were investigated. The ability of alkaline hydrolysis, sonication, and their combination to release NEP was assessed. Alkaline hydrolysis with sonication was found to extract the highest NEP content (7.3 ± 0.17 mg gallic acid equivalents (GAE)/g dry waste), which was higher than the extractable fraction. The highest yield was obtained after treatment of 2 M NaOH at 60 °C for 30 min of sonication. Quantification and identification were done using U(H)PLC-DAD and U(H)PLC-ESI-MS(E). Kaempferol and quercetin glucosides along with several phenolic acids were found. The results of the study show that there are higher amounts of valuable health-promoting compounds from cauliflower waste than what is currently described in the literature. PMID:24665894

Gonzales, Gerard Bryan; Smagghe, Guy; Raes, Katleen; Van Camp, John

2014-04-16

46

Asparagus stem as a new lignocellulosic biomass feedstock for anaerobic digestion: Increasing hydrolysis rate, methane production and biodegradability by alkaline pretreatment.  

PubMed

Recently, anaerobic digestion of lignocellulosic biomass for methane production has attracted considerable attention. However, there is little information regarding methane production from asparagus stem, a typical lignocellulosic biomass, by anaerobic digestion. In this study, alkaline pretreatment of asparagus stem was investigated for its ability to increase hydrolysis rate and methane production and to improve biodegradability (BD). The hydrolysis rate increased with increasing NaOH dose, due to higher removal rates of lignin and hemicelluloses. However, the optimal NaOH dose was 6% (w/w) according to the specific methane production (SMP). Under this condition, the SMP and the technical digestion time of the NaOH-treated asparagus stem were 242.3mL/g VS and 18days, which were 38.4% higher and 51.4% shorter than those of the untreated sample, respectively. The BD was improved from 40.1% to 55.4%. These results indicate that alkaline pretreatment could be an efficient method for increasing methane production from asparagus stem. PMID:24841574

Chen, Xiaohua; Gu, Yu; Zhou, Xuefei; Zhang, Yalei

2014-07-01

47

Phase transfer catalysis of alkaline hydrolysis of n-butyl acetate: Comparison of performance of batch and micro-reactors  

Microsoft Academic Search

The hydrolysis of n-butyl acetate with aqueous sodium hydroxide was studied in the batch mode as well as in the continuous mode in a micro-reactor. The progress of the reaction was analyzed both with and without a phase transfer catalyst. The concentration of the unreacted sodium hydroxide in the aqueous phase was determined by titration with hydrochloric acid to monitor

Siva Kumar Reddy Cherlo; K. Devaki; S. Pushpavanam

2010-01-01

48

Determination of the nitrogen content of nitrocellulose from smokeless gunpowders and collodions by alkaline hydrolysis and ion chromatography  

Microsoft Academic Search

In this work, a method to determine the nitrogen content of nitrocellulose from gunpowders and collodions is proposed. A basic hydrolysis of nitrocellulose with 1.0% (m\\/v) NaOH at 150°C during 30min was carried out for nitrocellulose from gunpowders (after its previous isolation by a protocol optimized by our research group) and from collodion samples. The concentration of nitrate and nitrite

María López-López; Jose María Ramiro Alegre; Carmen García-Ruiz; Mercedes Torre

2011-01-01

49

The study of the influence of surfactant charge on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) using spectrophotometric methods.  

PubMed

In this research, the effects of micellar systems on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) were found to be dependant upon the surfactant charge within the micelle. In cationic micelles, there is a catalytic effect at low concentrations of surfactant. However, this reaction is inhibited at higher surfactant concentrations. In anionic micelles, a catalytic effect occurs, while in zwitterionic and non-ionic micelles there is an inhibitory effect. Such reactions are attributable to changes in reactants on the micellar surface, or to the fact that both reactants are found in different microenvironments. The pseudophase (PS) and ion-exchange (PPIE) models were found to be consistent with the experimental result. Furthermore, the association constants for both drugs could be determined together with micellar rate constants in heterogeneous media. PMID:17498930

Ferrit, Mónica; del Valle, Carmen; Martínez, Fernando

2007-07-01

50

Phthalate Ester Hydrolysis: Linear Free Energy Relationships.  

National Technical Information Service (NTIS)

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 f...

N. L. Wolfe W. C. Steen L. A. Burns

1980-01-01

51

Reactivity of Tannic Acid with Common Corrosion Products and Its Influence on the Hydrolysis of Iron in Alkaline Solutions  

NASA Astrophysics Data System (ADS)

To ascertain the role of tannic acid in the anticorrosive protection of steels, the reaction between 5% tannic acid aqueous solutions with lepidocrocite, goethite, superparamagnetic goethite, akaganeite, poorly crystalline maghemite, magnetite and hematite was studied using color changes, infrared and Mössbauer spectroscopy. After three months of interaction with lepidocrocite, the formation of an iron tannate complex was detected by its dark blue color and confirmed by infrared and Mössbauer analysis. Evidence for the chemical transformation was obtained for goethite in nanoparticles and poorly crystalline maghemite after reaction for six months. The other iron compounds do not transform to another oxide or phase upon treatment with the tannic acid solution. These results showed that lepidocrocite is the most reactive phase and that the size and degree of crystallinity have strong influence on the formation of the tannate complexes. The precipitation of iron phases from alkaline solutions of iron (II) sulfate heptahydrate containing different amount of tannic acid and potassium nitrate as oxidative agent was also studied. Mössbauer and infrared results show that in the absence of tannic acid some common rust components are obtained (viz. goethite, superparamagnetic goethite, maghemite and non-stoichiometric magnetite). The presence of 0.1% tannic acid in a low alkalinity solution results in the precipitation of iron oxyhydroxides and some iron tannates. Concentrations of 1% tannic acid are required for the formation of the tannates complexes as main reaction product.

Jaén, J. A.; Araúz, E. Y.; Iglesias, J.; Delgado, Y.

2003-06-01

52

Pretreatment of wheat straw using combined wet oxidation and alkaline hydrolysis resulting in convertible cellulose and hemicellulose.  

PubMed

The wet oxidation process of wheat straw has been studied as a pretreatment method to attain our main goal: To break down cellulose to glucose enzymatic, and secondly, to dissolve hemicellulose (e.g., for fermentation) without producing microbial inhibitors. Wet oxidation combined with base addition readily oxidizes lignin from wheat straw facilitating the polysaccharides for enzymatic hydrolysis. By using a specially constructed autoclave system, the wet oxidation process was optimized with respect to both reaction time and temperature. The best conditions (20 g/L straw, 170 degrees C, 5 to 10 min) gave about 85% w/w yield of converting cellulose to glucose. The process water, containing dissolved hemicellulose and carboxylic acids, has proven to be a direct nutrient source for the fungus Aspergillus niger producing exo-beta-xylosidase. Furfural and hydroxymethyl-furfural, known inhibitors of microbial growth when other pretreatment systems have been applied, were not observed following the wet oxidation treatment. PMID:18623619

Bjerre, A B; Olesen, A B; Fernqvist, T; Plöger, A; Schmidt, A S

1996-03-01

53

Determination of the nitrogen content of nitrocellulose from smokeless gunpowders and collodions by alkaline hydrolysis and ion chromatography.  

PubMed

In this work, a method to determine the nitrogen content of nitrocellulose from gunpowders and collodions is proposed. A basic hydrolysis of nitrocellulose with 1.0% (m/v) NaOH at 150°C during 30 min was carried out for nitrocellulose from gunpowders (after its previous isolation by a protocol optimized by our research group) and from collodion samples. The concentration of nitrate and nitrite ions in the hydrolysate was determined by ion chromatography with suppression and conductimetric detection. The nitrogen content of nitrocellulose was calculated from the values of the concentration of both ions. The quantitative method was evaluated in terms of selectivity, sensitivity, robustness, limits of detection and quantification, and precision, measured as repeatability and intermediate precision. These parameters were good enough to demonstrate the validity of the method and its applicability to the determination of the nitrogen content of nitrocellulose contained in different types of gunpowders (single- and double-base gunpowders, manufactured from 1944 to 1997) and in commercial collodion samples. For gunpowders, the nitrogen content determined with the optimized method was compared with the values reported by the official label of the ammunition (obtained by a digestion/titration method) and errors, by defect, ranging from 1% to 15.2% (m/m) were calculated. The highest errors were obtained for the oldest gunpowders and could be attributed to the loss of nitro groups in the nitrocellulose molecule during aging. For collodion samples, errors could not be calculated since the real nitrogen content for these samples was not given in the label. In addition, the analysis time (2h for nitrocellulose isolation, 1.5h for nitrocellulose hydrolysis, and 0.2h for chromatographic separation) was about 10 times lower than in the digestion/titration method nowadays used for gunpowder samples. PMID:21168569

López-López, María; Alegre, Jose María Ramiro; García-Ruiz, Carmen; Torre, Mercedes

2011-01-31

54

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.

2014-01-01

55

The hydrolysis of bile acid conjugates.  

PubMed

Studies were made of a) the relationship of bile acid structure and analytical recoveries (measured by 3-hydroxysteroid oxidoreductase) following vigorous alkaline hydrolysis of bile acid conjugates and b) the relationship of structure and hydrolysis time of taurine- and glycine bile acid conjugates in a reaction catalyzed by glycocholic acid hydrolase. Alkaline hydrolysis resulted in good recoveries of hydroxy and 7 and 12- oxo-bile acids but poor recoveries of 3-oxo-bile acids. Borohydride reduction of the 3-oxo-acids prevented these losses. Complete enzymatic hydrolysis of glycine conjugated bile acids was about five times more rapid than that of taurine conjugates. Hydrolysis of conjugates containing oxo groups was slow. Borohydride reduction of oxo-acids corrected this and did not inhibit enzymatic hydrolysis. It was concluded that both vigorous alkaline and enzymatic hydrolysis are satisfactory in bile acid assays if borohydride reduction is instituted before the hydrolytic step. However, due to the presence of possible enzyme inhibitors and solubility difficulties, strong alkaline hydrolysis is preferable to enzymatic hydrolysis in fecal bile acid determinations at this time. PMID:715825

Beher, W T; Stradnieks, S; Beher, G R; Lin, G J

1978-10-01

56

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

57

Effect of hydrolysis on identifying prenatal cannabis exposure  

PubMed Central

Identification of prenatal cannabis exposure is important due to potential cognitive and behavioral consequences. A two-dimensional gas chromatography–mass spectrometry method for cannabinol, ?9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), 8?,11-dihydroxy-THC, and 11-nor-9-carboxy-THC (THCCOOH) quantification in human meconium was developed and validated. Alkaline, enzymatic, and enzyme–alkaline tandem hydrolysis conditions were optimized with THC- and THCCOOH-glucuronide reference standards. Limits of quantification ranged from 10 to 15 ng/g, and calibration curves were linear to 500 ng/g. Bias and intra-day and inter-day imprecision were <12.3%. Hydrolysis efficiencies were analyte-dependent; THC-glucuronide was effectively cleaved by enzyme, but not base. Conversely, THCCOOH-glucuronide was most sensitive to alkaline hydrolysis. Enzyme–alkaline tandem hydrolysis maximized efficiency for both glucuronides. Identification of cannabinoid-positive meconium specimens nearly doubled following alkaline and enzyme–alkaline hydrolysis. Although no 11-OH-THC glucuronide standard is available, enzymatic hydrolysis improved 11-OH-THC detection in authentic specimens. Maximal identification of cannabis-exposed neonates and the widest range of cannabis biomarkers are achieved with enzyme–alkaline tandem hydrolysis.

Gray, Teresa R.; Barnes, Allan J.

2011-01-01

58

Alkaline phosphatase: an overview.  

PubMed

Alkaline phosphatase (ALP; E.C.3.I.3.1.) is an ubiquitous membrane-bound glycoprotein that catalyzes the hydrolysis of phosphate monoesters at basic pH values. Alkaline phosphatase is divided into four isozymes depending upon the site of tissue expression that are Intestinal ALP, Placental ALP, Germ cell ALP and tissue nonspecific alkaline phosphatase or liver/bone/kidney (L/B/K) ALP. The intestinal and placental ALP loci are located near the end of long arm of chromosome 2 and L/B/K ALP is located near the end of the short arm of chromosome 1. Although ALPs are present in many mammalian tissues and have been studied for the last several years still little is known about them. The bone isoenzyme may be involved in mammalian bone calcification and the intestinal isoenzyme is thought to play a role in the transport of phosphate into epithelial cells of the intestine. In this review, we tried to provide an overview about the various forms, structure and functions of alkaline phosphatase with special focus on liver/bone/kidney alkaline phosphatase. PMID:24966474

Sharma, Ujjawal; Pal, Deeksha; Prasad, Rajendra

2014-07-01

59

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....

60

Simultaneous GC-EI-MS Determination of ?9-Tetrahydrocannabinol, 11-Hydroxy-?9-Tetrahydrocannabinol, and 11-nor-9-Carboxy-?9-Tetrahydrocannabinol in Human Urine Following Tandem Enzyme-Alkaline Hydrolysis  

PubMed Central

A sensitive and specific method for extraction and quantification of ?9-tetrahydrocannabinol (THC), 11-hydroxy-?9-tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-?9-tetrahydrocannabinol (THCCOOH) in human urine was developed and fully validated. To ensure complete hydrolysis of conjugates and capture of total analyte content, urine samples were hydrolyzed by two methods in series. Initial hydrolysis was with Escherichia coli ?-glucuronidase (Type IX–A) followed by a second hydrolysis utilizing 10N NaOH. Specimens were adjusted to pH 5?6.5, treated with acetonitrile to precipitate protein, and centrifuged, and the supernatants were subjected to solid-phase extraction. Extracted analytes were derivatized with BSTFA and quantified by gas chromatography–mass spectrometry with electron impact ionization. Standard curves were linear from 2.5 to 300 ng/mL. Extraction efficiencies were 57.0?59.3% for THC, 68.3?75.5% for 11-OH-THC, and 71.5?79.7% for THCCOOH. Intra- and interassay precision across the linear range of the assay ranged from 0.1 to 4.3% and 2.6 to 7.4%, respectively. Accuracy was within 15% of target concentrations. This method was applied to the analysis of urine specimens collected from individuals participating in controlled administration cannabis studies, and it may be a useful analytical procedure for determining recency of cannabis use in forensic toxicology applications.

Abraham, Tsadik T.; Lowe, Ross H.; Pirnay, Stephane O.; Darwin, William D.; Huesti, Marilyn A.

2009-01-01

61

Are 1,5- and 1,7-dihydrodiimidazo[4,5-b:4?,5?-e]pyrazine the main products of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) alkaline hydrolysis? A DFT study of vibrational spectra  

NASA Astrophysics Data System (ADS)

The fully optimized geometries and force fields of the most stable conformation of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane and two tautomers 1,5- and 1,7-dihydrodiimidazo[4,5- b:4',5'- e]pyrazine were obtained at the B3LYP level of hybrid density functional theory with the 6-31G(d) basis set. The vibrational frequencies were calculated by scaling of force fields, and the vibrational spectra were interpreted taking into account potential energy distributions. DFT calculations provide good agreement between calculated and experimental vibrational frequencies, obtained for CL-20. The theoretical vibrational spectra of 1,5- and 1,7-dihydrodiimidazo[4,5- b:4',5'- e]pyrazine correspond to the experimental FTIR spectrum obtained for the CL-20 alkaline hydrolysis products.

Kholod, Yana; Okovytyy, Sergiy; Kuramshina, Gulnara; Qasim, Mohammad; Gorb, Leonid; Furey, John; Honea, Patricia; Fredrickson, Herbert; Leszczynski, Jerzy

2006-08-01

62

O-Carbonyl-Assisted Alkaline Hydrolyses of Methyl Benzoates.  

National Technical Information Service (NTIS)

The rates of alkaline hydrolysis of methyl 6-methyl-2-benzoylbenzoate, methyl 6-methyl-2-acetylbenzoate, methyl 6-chloro-2-benzoylbenzoate, methyl 6-chloro-2-acetylbenzoate, and the 6-unsubstituted analogs have been measured. In each case the 6-substitute...

M. S. Newman A. L. Leegwater

1968-01-01

63

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...

64

The Hydrolysis of Carbonyl Sulfide at Low Temperature: A Review  

PubMed Central

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.

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

2013-01-01

65

Enzymatic hydrolysis of esterified diarrhetic shellfish poisoning toxins and pectenotoxins  

Microsoft Academic Search

Okadaic acid (OA) and dinophysistoxins-1 and -2 (DTX1, DTX2), the toxins responsible for incidents of diarrhetic shellfish\\u000a poisoning (DSP), can occur as complex mixtures of ester derivatives in both plankton and shellfish. Alkaline hydrolysis is\\u000a usually employed to release parent OA\\/DTX toxins, and analyses are conducted before and after hydrolysis to determine the\\u000a concentrations of nonesterified and esterified toxins. Recent

Erin Doucet; Neil N. Ross; Michael A. Quilliam

2007-01-01

66

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

67

Towards zero discharge of chromium-containing leather waste through improved alkali hydrolysis  

Microsoft Academic Search

The treatment of chromium-containing leather waste (CCLW), the major solid waste generated at the post-tanning operations of leather processing, has the potential to generate value-added leather chemicals. Various alkali and enzymatic hydrolysis were compared, and calcium oxide was found to be important for effective (but still incomplete) hydrolysis. Three possible reasons are given for the incomplete hydrolysis under alkaline conditions.

Changdao Mu; Wei Lin; Mingrang Zhang; Qingshi Zhu

2003-01-01

68

Structure-activity correlations for organophosphorus ester anticholinesterases. Part 2: CNDO/2 calculations applied to ester hydrolysis rates  

NASA Technical Reports Server (NTRS)

Quantitative structure-activity relationships are presented for the hydrolysis of organophosphorus esters, RR'P(O)X, where R and R' are alkyl and/or alkoxy groups and X is fluorine, chlorine or a phenoxy group. CNDO/2 calculations provide values for molecular parameters that correlate with alkaline hydrolysis rates. For each subset of esters with the same leaving group, X, the CNDO-derived net atomic charge at the central phosphorus atom correlates well with the alkaline hydrolysis rate constants. For the whole set of esters with different leaving groups, equations are derived that relate charge, orbital energy and bond order to the hydrolysis rate constants.

Johnson, H.; Kenley, R. A.; Rynard, C.; Golub, M. A.

1984-01-01

69

Enzymatic hydrolysis of molasses  

Microsoft Academic Search

Kinetic studies of the enzymatic hydrolysis of molasses were conducted using glucoamylase. Central Sugar Refinery SDN BHD contains 13–20% glucose. The molasses was diluted and the kinetic experiments were conducted at 67 °C with 100–1000 mg\\/l of glucoamylase. The glucose contents of the molasses were enhanced after hydrolysis of molasses solution with 1000 mg\\/l glucoamylase. A Lineweaver–Burk plot was obtained

Ghasem D. Najafpour; Cheong Poi Shan

2003-01-01

70

Acid hydrolysis of chitosans  

Microsoft Academic Search

The hydrolysis of the O-glycosidic linkages (depolymerization) and the N-acetyl linkage (de-N-acetylation) of partially N-acetylated chitosans were studied in dilute and concentrated HCl. The rate of hydrolysis of the glycosidic linkages was found to be equal to the rate of de-N-acetylation in dilute acid, while the glycosidic linkages was hydrolysed more than 10 times faster than the N-acetyl linkage in

K. M. Vårum; M. H. Ottøy; O. Smidsrød

2001-01-01

71

New Approaches in Modeling Carbonate Alkalinity and Total Alkalinity  

Microsoft Academic Search

Alkaline measurements (carbonate alkalinity and total alkalinity) are of great importance in analyses of ocean, marine, lake and river waters, and other samples. Carbonate alkalinity (CA) refers to the cases in which only bicarbonate and carbonate species are considered. Total alkalinity (Alk) implies additional species having acid-base properties. Biochemical processes give rise to the organic alkalinity (OA) in natural waters.

Tadeusz Micha?owski; Agustin G. Asuero

2012-01-01

72

Chemostat Culture of Escherichia coli K-12 Limited by the Activity of Alkaline Phosphatase  

PubMed Central

The growth-limiting reaction of a chemostat culture of Escherichia coli K-12 was the hydrolysis of ?-glycerophosphate by alkaline phosphatase. The culture was buffered at pH 5.2 where alkaline phosphatase was unable to supply phosphate to the cell at a rate sufficient to sustain the maximum rate of growth. Alkaline phosphatase activity in this system is discussed in terms of the so-called Flip-Flop mechanism.

King, Stagg L.; Francis, J. C.

1975-01-01

73

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

74

Comparative study on chemical pretreatments to accelerate enzymatic hydrolysis of aquatic macrophyte biomass used in water purification processes  

Microsoft Academic Search

In this study, enzymatic hydrolysis of two floating aquatic plants which are suitable for water purification, water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.), was performed to produce sugars. Twenty chemical pretreatments were comparatively examined in order to improve the efficiency of enzymatic hydrolysis. As a result, the alkaline\\/oxidative (A\\/O) pretreatment, in which sodium hydroxide and hydrogen peroxide

D. Mishima; M. Tateda; M. Ike; M. Fujita

2006-01-01

75

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

76

[Acid hydrolysis of mandioca].  

PubMed

The influence of time of hydrolysis, pression of the process, ratio of mass of flour and volume and concentration of the acid solution was studied in the hydrolytic processes for Cassava flour. The aim was to obtain fermentable sugars, and the results were submitted to variance analysis. PMID:1228838

Colombo, A J; Schneiderman, B; Baruffaldi, R; Nacco, R

1975-01-01

77

Hydrolysis of NaBH4 Using Electroless Ni Catalyst  

Microsoft Academic Search

The development of new storage materials will facilitate the use of hydrogen as a major energy vector in the near future. Chemical hydrides like NaBH4 have been tested as a possible precursor material for supplying hydrogen. In this study, catalytic hydrolysis of alkaline NaBH4 solution is studied using a Ni-based catalyst. The Ni catalysts were synthesized by Pd catalyzation and

Leelarani Katam

2007-01-01

78

Influence of acidic and alkaline aqueous regeneration on enzymatic digestibility of the cellulose fraction recovered from [amim]Cl-treated rice husk.  

PubMed

The recalcitrance of lignocelluloses toward enzymatic hydrolysis necessitates pretreatments. Ionic liquid pretreatment with 1-allyl-3-methylimidazolium chloride ([amin]Cl) was applied to risk husk and cellulose-containing fractions were recovered from the ionic liquid solutions by acidic, alkaline, and alkaline-acidic regeneration respectively. Enzymatic hydrolysis of the recovered materials was carried out and results demonstrated that: (i) acidic regeneration was not substantial to ensure enhanced enzymatic digestibility; (ii) alkaline regeneration increased the enzymatic hydrolysis; (iii) alkaline-acidic regeneration led to an almost complete hydrolysis of the carbohydrate fraction. The obtained results were rationalized by means of chromatographic analyses of soluble fractions collected after the different regeneration processes: the removal of hemicellulose, which increased going from the acidic to the alkaline-acidic regeneration, seemed to play a crucial role in enhancing the rice husk saccharification. PMID:23196254

Salanti, Anika; Zoia, Luca; Frigerio, Paola; Orlandi, Marco

2013-01-01

79

Hydrogen production from catalytic hydrolysis of sodium borohydride solution using nickel boride catalyst  

Microsoft Academic Search

A highly stable and active nickel boride catalyst (NixB) was prepared and tested for the catalytic hydrolysis of alkaline NaBH4 solution. It was found that after heat treatment at 150°C in vacuum the NixB catalyst shows greatly enhanced catalytic activity and operational stability. In the experimental conditions, the hydrolysis reaction can produce 6.75wt% hydrogen at 45°C and >4.0wt% hydrogen even

Dong Hua; Yang Hanxi; Ai Xinping; Cha Chuansin

2003-01-01

80

Alkaline "Permanent" Paper.  

ERIC Educational Resources Information Center

Discussion of paper manufacturing processes and their effects on library materials focuses on the promotion of alkaline "permanent" paper, with less acid, by Canadian library preservation specialists. Standards for paper acidity are explained; advantages of alkaline paper are described, including decreased manufacturing costs; and recyclability is…

Pacey, Antony

1991-01-01

81

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) [Latham, NY

2011-02-01

82

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

83

Progressing Batch Hydrolysis Reactor  

SciTech Connect

In all dilute acid hydrolysis processes for glucose production, conditions severe enough to hydrolyze crystalline cellulose to glucose are also severe enough to degrade the glucose into undesirable compounds such as hydroxy-methylfurfural (HMF), levulinic acid, and formic acid. One way to minimize the sugar degradation is to remove the sugars from the reaction zone before substantial degradation occurs. Sugars are most efficiently removed by a reactor system that uses countercurrent flow of liquids and solids, which allows simultaneous achievement of high yields and high sugar concentrations. The progressing batch hydrolysis process, invented and now under development at SERI, uses several percolation reactors in series to simulate countercurrent flow of liquids and solids. In this way, the advantages of countercurrent flow are achieved, and the mechanical and operational simplicity of the percolation reactor is retained. This paper describes the theory and operation of the progressing batch hydrolysis reactor and presents the results of our mathematical modeling of the system. 25 refs., 7 figs.

Wright, J.D.; Bergeron, P.W.; Werdene, P.J.

1985-09-01

84

Organophosphate and Organophosphorothionate Esters: Application of Linear Free Energy Relationships to Estimate Hydrolysis Rate Constants for Use in Environmental Fate Assessment.  

National Technical Information Service (NTIS)

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 a...

N. L. Wolf

1980-01-01

85

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

86

Thermostable Enzymes in Lignocellulose Hydrolysis  

Microsoft Academic Search

Thermostable enzymes offer potential benefits in the hydrolysis of lignocellulosic substrates; higher\\u000a specific activity decreasing the amount of enzymes, enhanced stability allowing improved hydrolysis performance\\u000a and increased flexibility with respect to process configurations, all leading to improvement of the overall\\u000a economy of the process. New thermostable cellulase mixtures were composed of cloned fungal enzymes for\\u000a hydrolysis experiments. Three thermostable cellulases,

Liisa Viikari; Marika Alapuranen; Terhi Puranen; Jari Vehmaanperä; Matti Siika-aho

87

Direct and Alkaline Glycerol Liquefaction of Hazelnut Shell  

Microsoft Academic Search

Hazelnut shell was liquefied directly in water at 530–710 K and in glycerol and alkaline (10% sodium carbonate) glycerol at 523–603 K temperature range. Thermal degradation of biomass, cellulose, hemicelluloses, and products were formed as well as a solid residue of char in low temperatures. In the liquefaction process, the micellar-like broken down fragments produced by hydrolysis are degraded to

A. Demirbas

2010-01-01

88

Role of Drosophila alkaline ceramidase (Dacer) in Drosophila development and longevity  

Microsoft Academic Search

Ceramidases catalyze the hydrolysis of ceramides to generate sphingosine (SPH) and fatty acids, and ceramide metabolism is\\u000a implicated in various biological responses in Drosophila melanogaster. Here we report the cloning, biochemical characterization, and functional analysis of a Drosophila alkaline ceramidase (Dacer). Dacer, a membrane-bound protein of 284 amino acids, shares homology with yeast and mammalian\\u000a alkaline ceramidases. Overexpression of Dacer

Qiong Yang; Zhong-Jun Gong; Ying Zhou; Jing-Qun Yuan; Jiaan Cheng; Lin Tian; Sheng Li; Xin-Da Lin; Ruijuan Xu; Zeng-Rong Zhu; Cungui Mao

2010-01-01

89

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

90

Vacuolar Acid hydrolysis as a physiological mechanism for sucrose breakdown.  

PubMed

Sucrose breakdown in mature acidic ;Persian' limes (Citrus aurantifolia [Christm.] Swing.) occurred at a rate of 30.6 picomoles per milliliter per day during 9 weeks storage at 15 degrees C. Neither enzyme of sucrose catabolism (sucrose synthase or acid/alkaline invertase) was present in extracts of mature storage tissue. The average vacuolar pH, estimated by direct measurement of sap from isolated vacuoles and by the methylamine method, was about 2.0 to 2.2. In vitro acid hydrolysis of sucrose at physiological concentrations in a buffered solution (pH 2.2) occurred at identical rates as in matured limes. The results indicate that sucrose breakdown in stored mature acidic limes occurs by acid hydrolysis. PMID:16666803

Echeverria, E; Burns, J K

1989-06-01

91

Alkaline flooding injection strategy  

SciTech Connect

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

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

1992-03-01

92

Economics of Enzymatic Hydrolysis Processes.  

National Technical Information Service (NTIS)

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 tho...

J. D. Wright

1988-01-01

93

Alkaline phytase from Lilium longiXorum: PuriWcation and structural characterization  

Microsoft Academic Search

Phytases catalyze the hydrolysis of phytic acid (myo-inositol hexakisphosphate), the most abundant inositol phosphate in cells. Phytases are of great commercial importance because their use as food and animal feed supplement has been approved by many countries to alleviate environmental and nutritional problems. Although acid phytases have been extensively studied, information regarding alka- line phytases is limited. Alkaline phytases with

Barry G. Garchow; Sonali P. Jog; Bakul Dhagat Mehta; Jodi M. Monosso; Pushpalatha P. N. Murthy

2006-01-01

94

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

95

Enzymatic hydrolysis of bacterial cellulose  

Microsoft Academic Search

Native cellulose from the bacterium Acetobacter xylinum as well as acid-treated bacterial cellulose prepared from partial hydrolysis of the native bacterial cellulose with 2.5 N HCl were subjected to enzymatic hydrolysis by Trichoderma viride cellobiohydrolase I (CBH I) and endoglucanase II (EG II). The activities of the two enzymes were continuously monitored with an oxidation-reduction potential electrode based on the

Masahiro Samejima; Junji Sugiyama; Kiyohiko Igarashi; Karl-Erik L. Eriksson

1997-01-01

96

The measurement of alkaline phosphatase at nanomolar concentration within 70 s using a disposable microelectrochemical transistor.  

PubMed

We report a new approach to the measurement of alkaline phosphatase concentration based on the use of a disposable poly(aniline) microelectrochemical transistor. The measurement is carried out in a two cell configuration in which the poly(aniline) microelectrochemical transistor operates in acid solution and is connected to the alkaline buffer solution containing the analyte by a salt bridge. Disposable microelectrochemical transistors were reproducibly fabricated by electrochemical deposition of poly(aniline) onto photolithographically fabricated gold microband arrays. Using these devices alkaline phosphatase was detected by employing p-aminophenyl phosphate as the substrate for the enzyme and using glucose and glucose oxidase to recycle the p-aminophenol generated upon enzyme catalysed hydrolysis of the phosphate. Recycling the p-aminophenol with glucose and glucose oxidase amplified the detection of alkaline phosphatase approximately tenfold. Using this approach we obtain linear calibration curves for alkaline phosphatase up to 5 nM within 70 s on single use devices. PMID:15219247

Astier, Y; Bartlett, P N

2004-08-01

97

Metabolism of poly- -hydroxybutyrate: effect of mild alkaline extraction on native poly- -hydroxybutyrate granules.  

PubMed

Mild alkaline extraction of native poly-beta-hydroxybutyrate (PHB) granules results in the solubilization of a protein fraction. Both the solubilized protein fraction and the extracted granules are essentially devoid of PHB synthetase activity unless recombined. The protein fraction has been separated by chromatography into two components (A-I and A-II). A-I but not A-II can be recombined with extracted granules to give rise to PHB synthetase activity. Extracted granules no longer require pretreatment with activator or trypsin but are directly susceptible to hydrolysis by Rhodospirillum rubrum depolymerase. Addition of A-II or A-I prevents the direct hydrolysis by depolymerase. The inhibition is reversed by activator or trypsin. We conclude that native granules are associated with a protein inhibitor which prevents the hydrolysis of PHB by depolymerase unless the protein is destroyed by trypsin, removed by alkaline extraction, or modified by activator. PMID:5001870

Griebel, R J; Merrick, J M

1971-11-01

98

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, III, C. A.

2005-01-01

99

Role of alkaline ceramidases in the generation of sphingosine and its phosphate in erythrocytes  

PubMed Central

Plasma sphingosine-1-phosphate (S1P) has been suggested to mainly originate from erythrocytes; however, within the erythrocyte, how sphingosine (SPH) generation—the precursor to S1P—is controlled is unknown. SPH is only generated from the hydrolysis of ceramides via ceramidases. Five human ceramidases have been identified: 1 acid, 1 neutral, and 3 alkaline ceramidases (ACER1, ACER2, and ACER3). Here, we demonstrate that only alkaline ceramidase activity is expressed in erythrocytes and that it is instrumental for SPH generation. Erythrocytes have alkaline but not acid or neutral ceramidase activity on D-e-C18:1-ceramide, a common substrate of ceramidases. Not only alkaline ceramidase activity but also the generation of SPH and S1P are increased during erythroid differentiation in K562 erythroleukemic cells. Such SPH and S1P increases were inhibited by the alkaline ceramidase inhibitor D-e-MAPP, suggesting that alkaline ceramidases have a role in the generation of SPH and S1P in erythroid cells. Alkaline ceramidase activity is highly expressed in mouse erythrocytes, and intravenous administration of D-e-MAPP decreased both SPH and S1P in erythrocytes and plasma. Collectively, these results suggest that alkaline ceramidase activity is important for the generation of SPH, the S1P precursor in erythrocytes.—Xu, R., Sun, W., Jin, J., Obeid, L. M., Mao, C. Role of alkaline ceramidases in the generation of sphingosine and its phosphate in erythrocytes.

Xu, Ruijuan; Sun, Wei; Jin, Junfei; Obeid, Lina M.; Mao, Cungui

2010-01-01

100

Enzymatic hydrolysis of diloxanide furoate in the presence of beta-cyclodextrin and its methylated derivatives.  

PubMed

In this study, we investigated the susceptibility to enzymatic and alkaline hydrolysis of diloxanide furoate (DF) and its cyclodextrin inclusion complexes, in aqueous solution. The cyclodextrins (CDs) utilized were beta-cyclodextrin (beta-CD), (2,6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD) and (2,3,6-tri-O-methyl)-beta-cyclodextrin (TM-beta-CD). All cyclodextrins studied provided a stabilizing effect to diloxanide furoate hydrolysis. In alkaline hydrolysis (pH 10.75), without the enzyme, beta-CD and TM-beta-CD provided similar effect on the stability of DF, with an inhibition factor in the order of 2.0. The DM-beta-CD, on the other hand, provided more pronounced stabilization effect than the other two CDs, with an inhibition factor around of 8. The maximum activity of the enzyme occured around pH 7.0. In the presence of enzyme, all cyclodextrins produced similar effect, with a DF hydrolysis inhibition factor in the order of 10. However, the plot of rate of hydrolysis versus [CD] fit with a equation based in a model that considers the association of the enzyme with the CDs. Therefore, it is concluded that the stabilization of DF is not only due to its cyclodextrin complex but also due to enzyme inhibition by cyclodextrin complexation. PMID:14602387

Monteiro, Julieta B; Chiaradia, Louise D; Brandão, Tiago A S; Magro, Jacir Dal; Yunes, Rosendo A

2003-11-28

101

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

102

Kinetics of iodine hydrolysis in unbuffered solutions  

SciTech Connect

The kinetics of hydrolysis or disproportionation of hypoiodite were studied spectrophotometrically in basic solution at an ionic strength of 0.2 M as a function of pH, iodide and total iodine concentration, and temperature. The existence of three independent pathways for this second-order process was confirmed. The pH-stat method was used to monitor the corresponding reaction of hypoiodous acid in weakly alkaline solution. The generalized rate law for the disproportionation is: /minus/d((HOI) + (OI/sup /minus//))dt = k /sub a/(HOI)/sup 2/ + k/sub b/(HOI) (OI/sup /minus//) + k/sub c/(OI/sup /minus//)/sup 2/ + k/sub d/(I/sub 2/OH/sup /minus//) (OI/sup /minus//). The values of k/sub a/ and k/sub b/ are substantially smaller than previously reported. However, an unexplained contribution to the rate law resulting from the pH-stat measurements was also obtained. The rapid recombination of iodide and iodate in HClO/sub 4/ solutions was followed by stopped-flow spectrophotometry at three ionic strengths, and over a range of iodide and hydrogen ion concentrations, and at eight temperatures. Fifth-order kinetics were observed with no detectable induction period. 14 refs., 4 figs., 1 tab.

Palmer, D.A.; Lyons, L.J.

1988-01-01

103

Salt Effects on an Ion–Molecule Reaction—Hydroxide-Catalyzed Hydrolysis of Benzocaine  

Microsoft Academic Search

\\u000a Purpose  This work investigates the effect of various salts on the rate of a reaction involving a neutral species (benzocaine alkaline\\u000a hydrolysis).\\u000a \\u000a \\u000a \\u000a Methods  Benzocaine hydrolysis kinetics in NaOH solutions in the presence of different salts were studied at 25C. Benzocaine solubility\\u000a in salt solutions was also determined. Solubility data were used to estimate salt effects on benzocaine activity coefficients,\\u000a and pH was

Ahmad Al-Maaieh; Douglas R. Flanagan

2006-01-01

104

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...

105

Copper Plating from Non-Cyanide Alkaline Baths  

NASA Astrophysics Data System (ADS)

Non-cyanide alkaline bath was used to prepare copper thin films. Influences of various temperatures on deposition rates, surface morphologies and microstructures of films were investigated. Copper thin films prepared from non-cyanide alkaline bath show typical nodular structures. Copper films fabricated at higher temperature possess rough surface due to hydrolysis of complexing agents. According to the XRD patterns, all deposited films were crystalline and showed Cu (111), Cu (200) and Cu (220) peaks. The intensity of peak (200) increases gradually with the rise on bath temperatures. Films with maximum thickness (7.5 ?m) could be obtained at the temperature of 40°C. From the cyclic voltammetry curve, it was found that the cathodic polarization decreased slightly with increase of bath temperatures. In addition, when the bath temperature was equal to 50°C, current efficiency could reach to 96.95%.

Li, Minggang; Wei, Guoying; Wang, Jianfang; Li, Meng; Zhao, Xixi; Bai, Yuze

2014-12-01

106

Semicontinuous enzymatic hydrolysis of lignocelluloses.  

PubMed

Lignocelluloses (steamed hardwood and hardwood kraft pulp) were semicontinuously hydrolyzed on a large scale [2-2. 5 kg of substrate vs. 20, 000 IU filter paperase (FPase)] using a 10-L hydrolysis reactor with an ultrafiltration unit for the recovery and reuse of cellulases. The substrate was added to the reactor at appropriate intervals to keep a concentration of approximately 5% (w/v). All of the enzyme was added at the beginning and no further addition was done. The ultrafiltration unit was operated intermittently rather than continuously due to its enough capacity (dilution rate of 2.5 h(-1)) and making the enzyme durable. The enzyme required to produce one gram of reducing sugar in this reactor was 27.3 FPase IU/g RS for steamed hardwood and 7.4 FPase IU/g RS for hardwood kraft pulp. The sugar composition of hydrolyzate was unaltered virtually from beginning to end of the hydrolysis in spite of the progressive loss of enzyme activities. The analysis of the enzyme composition in the hydrolyzate during hydrolysis revealed that an exo-beta-D-glucanase component was adsorbed selectively at the stages of advanced hydrolysis extent. PMID:18597319

Ishihara, M; Uemura, S; Hayashi, N; Shimizu, K

1991-04-25

107

Improved enzymatic hydrolysis of hair.  

PubMed

An enzymatic hair extraction method is proposed for drug analysis. Pronase digestion of various aliquots of hair from a cocaine abuser was preceded by a 2-h incubation with a dithiothreitol solution. The extraction solution was tested to identify possible interferences in the radioimmunoassay and was compared with other hydrolysis methods to assess the results of extraction. PMID:8138218

Offidani, C; Strano Rossi, S; Chiarotti, M

1993-12-01

108

Catalytic hydrolysis of sodium borohydride by a novel nickel–cobalt–boride catalyst  

Microsoft Academic Search

With the aim of designing an efficient hydrogen generator for portable fuel cell applications nickel–cobalt–boride (Ni–Co–B) catalysts were prepared by a chemical reduction method and their catalytic hydrolysis reaction with alkaline NaBH4 solution was studied. The performance of the catalysts prepared from NaBH4 solution with NaOH, and without NaOH show different hydrogen generation kinetics. The rate of hydrogen generation was

J. C. Ingersoll; N. Mani; J. C. Thenmozhiyal; A. Muthaiah

2007-01-01

109

Silica in alkaline brines  

USGS Publications Warehouse

Analysis of sodium carbonate-bicarbonate brines from closed basins in volcanic terranes of Oregon and Kenya reveals silica contents of up to 2700 parts per million at pH's higher than 10. These high concentrations of SiO 2 can be attributed to reaction of waters with silicates, and subsequent evaporative concentration accompanied by a rise in pH. Supersaturation with respect to amorphous silica may occur and persist for brines that are out of contact with silicate muds and undersaturated with respect to trona; correlation of SiO2 with concentration of Na and total CO2 support this interpretation. Addition of moredilute waters to alkaline brines may lower the pH and cause inorganic precipitation of substantial amounts of silica.

Jones, B. F.; Rettig, S. L.; Eugster, H. P.

1967-01-01

110

Dilute-Acid Hydrolysis of Lignocellulosic Biomass  

Microsoft Academic Search

In recent years, treatment of lignocellulosic biomass with dilute sulfuric acid has been primarily used as a means of hemicellulose\\u000a hydrolysis and pretreatment for enzymatic hydrolysis of cellulose. A significant advancement has also been made in the area\\u000a of dilute acid hydrolysis of cellulose. An overview of reactor theory as it applies to the dilute acid hydrolysis and recent\\u000a developments

Y. Y. Lee; Prashant Iyer; R. W. Torget

111

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

112

Chemical recycling of poly(ethylene terephthalate) (PET) by hydrolysis and glycolysis.  

PubMed

In this paper we review an interesting method of PET recycling, i.e. chemical recycling; it is based on the concept of depolymerizing the condensation polymer through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high-quality chemical products. In this work our attention is confined to the hydrolysis (neutral, acid and alkaline) and glycolysis processes of PET chemical recycling; operating conditions and mechanism of each method are reported and described. The neutral hydrolysis has an auto accelerating character; two kinetic models have been proposed: an half-order and a second order kinetic model. The acid hydrolysis could be explained by a modified shrinking core model under chemical reaction control and the alkaline hydrolysis by a first-order model with respect to hydroxide ion concentration. To describe glycolysis, two different kinetic models have been proposed where EG can act or not as internal catalyst. Further experimental and theoretical investigations are required to shed light on the promising processes of PET chemical recycling reviewed in this work. PMID:14699998

Carta, Daniela; Cao, Giacomo; D'Angeli, Claudio

2003-01-01

113

High solids enzymatic hydrolysis of pretreated lignocellulosic materials with a powerful stirrer concept.  

PubMed

In this study, we present a powerful stirred tank reactor system that can efficiently hydrolyse lignocellulosic material at high solid content to produce hydrolysates with glucose concentration > 100 g/kg. As lignocellulosic substrates alkaline-pretreated wheat straw and organosolv-pretreated beech wood were used. The developed vertical reactor was equipped with a segmented helical stirrer, which was specially designed for high biomass hydrolysis. The stirrer was characterised according to mixing behaviour and power input. To minimise the cellulase dosage, a response surface plan was used. With the empirical relationship between glucose yield, cellulase loading and solid content, the minimal cellulase dosage was calculated to reach at least 70% yield at high glucose and high substrate concentrations within 48 h. The optimisation resulted in a minimal enzyme dosage of 30 FPU/g dry matter (DM) for the hydrolysis of wheat straw and 20 FPU/g DM for the hydrolysis of beech wood. By transferring the hydrolysis reaction from shaking flasks to the stirred tank reactor, the glucose yields could be increased. Using the developed stirred tank reactor system, alkaline-pretreated wheat straw could be converted to 110 g/kg glucose (76%) at a solid content of 20% (w/w) after 48 h. Organosolv-pretreated beech wood could be efficiently hydrolysed even at 30% (w/w) DM, giving 150 g/kg glucose (72%). PMID:24242162

Ludwig, Daniel; Michael, Buchmann; Hirth, Thomas; Rupp, Steffen; Zibek, Susanne

2014-02-01

114

Surface modification of poly(ethylene terephthalate) via hydrolysis and layer-by-layer assembly of chitosan and chondroitin sulfate to construct cytocompatible layer for human endothelial cells  

Microsoft Academic Search

Surface modification of poly(ethylene terephthalate) (PET) film was performed by surface hydrolysis and layer-by-layer (LBL) assembly followed a mechanism of electrostatic adsorption of oppositely charged polymers, exemplified with chitosan and chondroitin sulfate (CS). Hydrolysis of PET in concentrated alkaline solution produced a carboxyl-enriched surface. The changes of weight loss and surface chemistry, morphology and wettability were monitored and verified by

Yunxiao Liu; Tao He; Changyou Gao

2005-01-01

115

The chlorination of hydrolysis lignin  

Microsoft Academic Search

Summary 1.Technical hydrolysis lignin is easily chlorinated at 20° by solutions of chlorine in carbon tetrachloride or by chlorine water. When 25–27% of chlorine is introduced, the latter is quantitatively removed from the solution by the lignin.2.The chlorine content of products chlorinated in carbon tetrachloide is very close to that required by calculation for the substitution reaction.3.When lignin is chlorinated

N. N. Shorygina; L. I. Kolotova

1953-01-01

116

Dilute acid hydrolysis of softwoods  

Microsoft Academic Search

Whole tree chips obtained from softwood forest thinnings were converted to ethanol via a two-stage dilute acid hydrolysis\\u000a followed by yeast fermentation. The chips were first impregnated with dilute sulfuric acid, then pretreated in a steam explosion\\u000a reactor to hydrolyze, more than 90% of the hemicellulose and approx 10% of the cellulose. The hydrolysate was filtered and\\u000a washed with water

Quang A. Nguyen; Melvin P. Tucker; Fred A. Keller; Delicia A. Beaty; Kevin M. Connors; Fannie P. Eddy

1999-01-01

117

Study of kinetic parameters in a mechanistic model for enzymatic hydrolysis of sugarcane bagasse subjected to different pretreatments.  

PubMed

The goal of this work is to evaluate the influence of different pretreatments in the kinetics of enzymatic hydrolysis of sugarcane bagasse and to propose a reliable methodology to easily perform sensitivity analysis and updating kinetic parameters whenever necessary. A kinetic model was modified to represent the experimental data of the batch enzymatic hydrolysis of sugarcane bagasse pretreated with alkaline hydrogen peroxide. The simultaneous estimation of kinetic parameters of the mathematical model was performed using the Pikaia genetic algorithm using batch hydrolysis experimental data obtained with different enzymatic loads. Subsequently, Plackett-Burman designs were used to identify the kinetic parameters with the higher influence on the dynamic behavior of the process variables, which were re-estimated to describe experimental data of the hydrolysis of bagasse pretreated with phosphoric acid + sodium hydroxide. The methodology was accurate and straightforward and can be used whenever there are changes in pretreatment conditions and/or fluctuations in biomass composition in different harvests. PMID:23474967

Neto, João Moreira; Dos Reis Garcia, Daniella; Rueda, Sandra Marcela Gómez; da Costa, Aline Carvalho

2013-11-01

118

Alkaline battery, separator therefore  

NASA Technical Reports Server (NTRS)

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

Schmidt, George F. (Inventor)

1980-01-01

119

Evaluation of Alkaline Cleaner Materials  

NASA Technical Reports Server (NTRS)

Alkaline cleaners used to process aluminum substrates have contained chromium as the corrosion inhibitor. Chromium is a hazardous substance whose use and control are described by environmental laws. Replacement materials that have the characteristics of chromated alkaline cleaners need to be found that address both the cleaning requirements and environmental impacts. This report will review environmentally friendly candidates evaluated as non-chromium alkaline cleaner replacements and methods used to compare those candidates one versus another. The report will also list characteristics used to select candidates based on their declared contents. It will also describe and evaluate methods used to discriminate among the large number of prospective candidates.

Partz, Earl

1998-01-01

120

Alkalinity of virgin solonetzes in northern Kalmykia (the Arshan-Zel'men Experimental Station)  

NASA Astrophysics Data System (ADS)

The alkalinity of virgin solonetzes of the Ergeni Upland, Ergeni Plain, and Sarpinsk Lowland has been studied. These soils are characterized by the neutral salinization and the high alkalinity of the solonetzic and subsolonetzic horizons. The analysis of the soil water extracts demonstrated that the highest alkalinity is typical of the subsolonetzic horizons containing calcium carbonates (the B2 and BCca horizons). In the solonetzic horizons without CaCO3, the alkalinity is lower despite the high exchangeable sodium percentage (up to 42%). The alkalinity of the solonetzic and subsolonetzic horizons may be conditioned by two processes: (a) the hydrolysis of the exchange complex (EC) containing sodium (EC-Na + H2O ? EC-H + Na+ + OH-) and (b) the reaction of the ion exchange with the substitution of calcium for sodium in the exchange complex (EC-2Na + CaCO3 ? EC-Ca + 2Na+ + CO{3/2-}). Calculations performed on the basis of the thermodynamic equations of the physicochemical equilibria according to the LIBRA program indicate that soda is absent in the solonetzic horizons, whose alkalinity is related to the carbonatecalcium equilibria. The high alkalinity of the calcareous subsolonetzic horizons is related to the presence of soda in combination with CaCO3. The formation of soda in these horizons is due to the reaction of ion exchange described by Gedroits.

Vorob'eva, L. A.; Klimanov, A. V.; Novikova, A. F.; Konyushkova, M. V.

2010-02-01

121

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.

2013-01-01

122

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 2.0MPa for 5min 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

123

Effects of chemical and enzymatic treatments on the hydrolysis of swine wastewater.  

PubMed

Slow degradation of swine wastewater mainly due to the particulate and recalcitrant organic matters is a main disadvantage of anaerobic digestion leading to very long solids retention time. Therefore, to accelerate hydrolysis known as the rate-limiting step of the overall digestion process, chemical treatment processes under various acidic and alkaline conditions as well as enzymatic treatment processes using cellulase and protease enzymes were tested for the hydrolysis of the swine wastewater. The effectiveness of various treatment processes was compared mainly by means of an increment of soluble organics in the treated swine wastewater. Among various treatment processes tested in this study, cellulase enzymatic treatment resulted in the most efficient hydrolysis of the swine wastewater. For the cellulase enzymatic hydrolysis, the observed hydrolytic constant value was 0.42 d(-1) and 26.6% of soluble organics in the swine wastewater increased within 12 hr. Compared to untreated swine wastewater, pre-treated swine wastewater by cellulase enzymatic process showed 10.7% higher anaerobic digestibility at the end of 20 d incubation and 29% higher initial methane production rate. These results further confirmed the transformation of particulate and recalcitrant organic compounds in the swine wastewater into soluble and relatively easily biodegradable organic products by the cellulase enzymatic hydrolysis. PMID:18957769

Lee, Y H; Chung, Y-C; Jung, J-Y

2008-01-01

124

Cobalt boride catalysts for hydrogen generation from alkaline NaBH 4 solution  

Microsoft Academic Search

Cobalt boride precursors were synthesized via chemical reaction of aqueous sodium borohydride with cobalt chloride, and followed by heat-treating at various temperatures. The as-prepared Co–B catalysts were characterized and analyzed by X-ray diffraction (XRD), nitrogen adsorption–desorption and catalytic activity test; and were adopted to help accelerating hydrolysis reaction of NaBH4 alkaline solution. The Co–B catalyst treated at 500 °C exhibits

Chuan Wu; Feng Wu; Ying Bai; Baolian Yi; Huamin Zhang

2005-01-01

125

High consistency enzymatic hydrolysis of hardwood substrates.  

PubMed

The feasibility of using a laboratory peg mixer to carry out high consistency enzymatic hydrolysis of lignocellulosic substrates was investigated. Two hardwood substrates, unbleached hardwood pulp (UBHW) and organosolv pretreated poplar (OPP), were used in this study. Hydrolysis of UBHW and OPP at 20% substrate consistency led to a high glucose concentration in the final hydrolysate. For example, a 48 h enzymatic hydrolysis of OPP resulted in a hydrolysate with 158 g/L of glucose. This is the highest glucose concentration ever obtained from enzymatic hydrolysis of lignocellulosic substrates. Fermentation of UBHW and OPP hydrolysates with high glucose content led to high ethanol concentrations, 50.4 and 63.1 g/L, respectively after fermentation. Our results demonstrate that using common pulping equipment to carry out high consistency hydrolysis can overcome the rheological problems and greatly increase the sugar and ethanol concentrations after the hydrolysis and fermentation. PMID:19643602

Zhang, Xiao; Qin, Wenjuan; Paice, Michael G; Saddler, John N

2009-12-01

126

Increase in ethanol production from sugarcane bagasse based on combined pretreatments and fed-batch enzymatic hydrolysis.  

PubMed

Enzymatic hydrolysis of pretreated sugarcane bagasse was performed to investigate the production of ethanol. The sugarcane bagasse was pretreated in a process combining steam explosion and alkaline delignification. The lignin content decreased to 83%. Fed-batch enzymatic hydrolyses was initiated with 8% (w/v) solids loading, and 10 FPU/g cellulose. Then, 1% solids were fed at 12, 24 or 48 h intervals. After 120 h, the hydrolysates were fermented with Saccharomyces cerevisiae UFPEDA 1238, and a fourfold increase in ethanol production was reached when fed-batch hydrolysis with a 12-h addition period was used for the steam pretreated and delignified bagasse. PMID:23201527

Wanderley, Maria Carolina de Albuquerque; Martín, Carlos; Rocha, George Jackson de Moraes; Gouveia, Ester Ribeiro

2013-01-01

127

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

128

Continuous monitoring of phospholipid vesicle hydrolysis by phospholipase D (PLD) reveals differences in hydrolysis by PLDs from 2 Streptomyces species.  

PubMed

Phospholipase D (PLD)-mediated hydrolysis of phosphatidylcholine (PC) in large unilamellar vesicles (LUVs) consisting of PC and either glycerol monooleate (GMO) or methyl oleate (MeO) were monitored in situ and in real time by using a choline oxidase-immobilized oxygen electrode. This technique revealed reaction differences between 2 bacterial PLDs. PLD from Streptomyces chromofuscus, which is closely homologous to bacterial alkaline phosphatase, hydrolyzed only 6% of surface PC owing to product inhibition. The catalytic activity of this enzyme was not sensitive to the addition of GMO. On the other hand, typical bacterial PLD from Streptomyces sp. was found to hydrolyze all the PC molecules at the outer surface of LUVs suggesting that this enzyme is free from product inhibition. Introduction of GMO or MeO into the bilayer increased exposure of the PC headgroup and facilitated PC hydrolysis mediated by PLD from Streptomyces sp. GMO and MeO have the same lipophilic tail but the latter lacks hydroxyl groups on its polar head. From kinetic analysis by using the Michaelis-Menten model extended to the reaction at the interface, these compounds were found to activate PLD from Streptomyces sp. in different ways, i.e., MeO increased the protein binding to membranes and GMO stimulated the enzyme-substrate complex formation at membrane surface. PMID:22391322

Hirano, Satomi; Sekine, Kazuhisa; Handa, Tetsurou; Nakano, Minoru

2012-06-01

129

Molecular and biochemical characterization of a new alkaline active multidomain xylanase from alkaline wastewater sludge.  

PubMed

A xylanase gene, xyn-b39, coding for a multidomain glycoside hydrolase (GH) family 10 protein was cloned from the genomic DNA of the alkaline wastewater sludge of a paper mill. Its deduced amino acid sequence of 1,481 residues included two carbohydrate-binding modules (CBM) of family CBM_4_9, one catalytic domain of GH 10, one family 9 CBM and three S-layer homology (SLH) domains. xyn-b39 was expressed heterologously in Escherichia coli, and the recombinant enzyme was purified and characterized. Xyn-b39 exhibited maximum activity at pH 7.0 and 60 °C, and remained highly active under alkaline conditions (more than 80 % activity at pH 9.0 and 40 % activity at pH 10.0). The enzyme was thermostable at 55 °C, retaining more than 90 % of the initial activity after 2 h pre-incubation. Xyn-b39 had wide substrate specificity and hydrolyzed soluble substrates (birchwood xylan, beechwood xylan, oat spelt xylan, wheat arabinoxylan) and insoluble substrates (oat spelt xylan and wheat arabinoxylan). Hydrolysis product analysis indicated that Xyn-b39 was an endo-type xylanase. The K (m) and V (max) values of Xyn-b39 for birchwood xylan were 1.01 mg/mL and 73.53 U/min/mg, respectively. At the charge of 10 U/g reed pulp for 1 h, Xyn-b39 significantly reduced the Kappa number (P < 0.05) with low consumption of chlorine dioxide alone. PMID:23117673

Zhao, Yanyu; Meng, Kun; Luo, Huiying; Huang, Huoqing; Yuan, Tiezheng; Yang, Peilong; Yao, Bin

2013-02-01

130

Synthesis of oxygen-free Titan tholins: implications in organic molecules product from hydrolysis  

NASA Astrophysics Data System (ADS)

Titan, the largest moon of Saturn, is known for its dense and nitrogen-rich atmosphere. The organic aerosols which are produced in Titan's atmosphere are objects of astrobiological interest. In this paper we focus on their potential chemical evolution when they reach the surface and interact with putative ammonia-water cryomagma[1]. In this context we have followed the evolution of alkaline pH hydrolysis (25wt% ammonia-water) of Titan tholins (produced by an experimental setup using a plasma DC discharge named PLASMA) at low temperature. Our group identified urea as the main product of tholins hydrolysis along with several amino acids (alanine, glycine and aspartic acid). However, those molecules have also been detected in non-hydrolyzed tholins meaning that oxygen gets in the PLASMA reactor during the tholins synthesis [2]. So the synthesis system has been improved by isolating the whole device in a specially designed glove box which protect the PLASMA experiment from the terrestrial atmosphere. After confirming the non-presence of oxygen in tholins produced with this new experimental setup, we performed alkaline pH hydrolysis of oxygen-free tholins in order to verify that organic molecules cited above are indeed in-situ produced. Those results will be exposed on the poster.

Brassé, C.; Raulin, F.; Coll, P.; Buch, A.

2013-09-01

131

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

132

Cotton cellulose: enzyme adsorption and enzymic hydrolysis  

Microsoft Academic Search

The adsorption of a crude cellulase complex from Trichoderma viride on variously pretreated cotton cellulose samples was studied in the framework of the Langmuir approach at 2-8 degrees. The saturation amount of adsorbed enzyme was related to the susceptibility of the substrates to hydrolysis. In every case the adsorption process was faster by 2-3 orders of magnitude than the hydrolysis

P. L. Beltrame; P. Carniti; B. Focher; A. Marzetti; M. Cattaneo

1982-01-01

133

Progress towards synthetic enzymes for phosphoester hydrolysis  

Microsoft Academic Search

Synthesis of artificial enzymes for catalyzing phosphoester hydrolysis has been attracting interest for a long time. The remarkable discovery that lanthanide ions catalyze the hydrolysis of DNA and RNA spurred the trend. Currently, progress is being made, mainly in the preparation of homogeneous catalysts, the promotion of catalytic activity by using acid\\/base cooperation within catalysts, the detailed understanding of the

Makoto Komiyama; Jun Sumaoka

1998-01-01

134

The use of ultra high-performance liquid chromatography for studying hydrolysis kinetics of CL-20 and related energetic compounds.  

PubMed

Ultra high-performance liquid chromatography (UHPLC) utilizes columns packed with sub-2-mum stationary-phase particles and allows operation with pressures of up to 15,000 psi to yield increased resolution, speed, and sensitivity versus conventional HPLC. This promising new technology was used for the analysis of energetic compounds (RDX, HMX and CL-20) and a selective method was developed on an Acquity UPLC. A fast UHPLC method was applied to determine alkaline hydrolysis reaction kinetics of major energetic compounds. Activation energies of alkaline hydrolysis reaction for CL-20, RDX and HMX were comparable to those in literature, however they were determined in a shorter amount of time due to the speed of analysis of the chromatographic method. The use of liophilic salts (KPF(6)) as mobile-phase additives for the enhancement of separation selectivity of energetic compounds was demonstrated. PMID:18644671

Makarov, Alexey; Lobrutto, Rosario; Christodoulatos, Christos; Jerkovich, Anton

2009-03-15

135

Alkaline Hydrolysis of Waste Poly(Ethylene Terephthalate): A Modified Shrinking Core Model  

Microsoft Academic Search

Hydrolytic decomposition of waste poly(ethylene terephthalate) (PET) is studied in the presence of an aqueous potassium hydroxide solution. A modified shrinking core model with a depleting product layer of waste PET is developed under finite solution volume conditions. An analytical solution is obtained for the model based on average molar distribution coefficient of aqueous potassium hydroxide solution. This model assumes

Santosh Kumar; Chandan Guria

2005-01-01

136

Hydrolysis of phosphotriesters: a theoretical analysis of the enzymatic and solution mechanisms.  

PubMed

A theoretical study on the alkaline hydrolysis of paraoxon, one of the most popular organophosphorus pesticides, in aqueous solution and in the active site of Pseudomonas diminuta phosphotriesterase (PTE) is presented. Simulations by means of hybrid quantum mechanics/molecular mechanics (QM/MM) potentials show that the hydrolysis of paraoxon takes place through an A(N)D(N) or associative mechanism both in solution and in the active site of PTE. The results correctly reproduce the magnitude of the activation free energies and can be used to rationalize the observed kinetic isotope effects (KIEs) for the hydrolysis of paraoxon in both media. Enzymatic hydrolysis of O,O-diethyl p-chlorophenyl phosphate, a phosphotriester having a leaving group with higher pK(a) than paraoxon, was also simulated. Hydrolysis of this phosphotriester by PTE follows a A(N)+D(N) mechanism with a pentacoordinate intermediate. Moreover, the leaving group of this new substrate coordinates to one of the zinc ions of the bimetallic active site in order to stabilize the large negative charge developed on the oxygen atom of the leaving group when the P-O bond is broken in the products state. To accommodate this new ligand in the coordination shell, carbamylated Lys169 must be displaced from one zinc ion to the other, which in turn affects the acidity of Asp301, a residue originally bound to the second zinc ion. This ability to displace some of the ligands of the coordination shell of the zinc centers would explain the promiscuity of this enzyme, which is capable of catalyzing hydrolysis of different substrate by means of different mechanisms. PMID:22745111

López-Canut, Violeta; Ruiz-Pernía, J Javier; Castillo, Raquel; Moliner, Vicent; Tuñón, Iñaki

2012-07-27

137

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.

2013-01-01

138

Astaxanthin preparation by lipase-catalyzed hydrolysis of its esters from Haematococcus pluvialis algal extracts.  

PubMed

Five of 8 fungal lipases screened were found to effectively hydrolyze astaxanthin esters from Haematococcus pluvialis algal cell extracts. Among these, an alkaline lipase from Penicillium cyclopium, expressed in Pichia pastoris, had the highest enzymolysis efficiency. Tween80 was shown to be an effective emulsifier in this lipase hydrolysis system for the 1st time. A series of experiments were performed to find optimal conditions for hydrolysis (pH, temperature, reaction time, lipase dosage). In the optimal reaction system, Tween80 and H. pluvialis extracts (mass ratio 1:1) were emulsified and added to the above lipase at a dosage of 4.6 U/?g (relative to total carotenoids), in phosphate buffer (0.1 M, pH 7.0), and incubated at 28 °C for 7 h, with agitation at 180 rpm. The free astaxanthin recovery ratio under these conditions was 63.2%. PMID:22417348

Zhao, Yingying; Guan, Feifei; Wang, Guili; Miao, Lili; Ding, Jing; Guan, Guohua; Li, Ying; Hui, Bodi

2011-05-01

139

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

140

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

141

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

142

The secondary alkaline zinc electrode  

NASA Astrophysics Data System (ADS)

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

McLarnon, Frank R.; Cairns, Elton J.

1991-02-01

143

Development of alkaline fuel cells.  

SciTech Connect

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

Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari [Colorado School of Mines, Golden, CO; Horan, James L. [Colorado School of Mines, Golden, CO; Caire, Benjamin R. [Colorado School of Mines, Golden, CO; Ziegler, Zachary C. [Colorado School of Mines, Golden, CO; Herring, Andrew M. [Colorado School of Mines, Golden, CO; Yang, Yuan [Colorado School of Mines, Golden, CO; Zuo, Xiaobing [Argonne National Laboratory, Argonne, IL; Robson, Michael H. [University of New Mexico, Albuquerque, NM; Artyushkova, Kateryna [University of New Mexico, Albuquerque, NM; Patterson, Wendy [University of New Mexico, Albuquerque, NM; Atanassov, Plamen Borissov [University of New Mexico, Albuquerque, NM

2013-09-01

144

Sucrose Hydrolysis at Limited Water Concentration.  

National Technical Information Service (NTIS)

To enable development of a model describing reaction kinetics in dehydrated foods, sucrose hydrolysis was studied at limited water concentration. Saturated sucrose solutions containing various acids and inert solid materials gave identical rate constants ...

T. Schoebel S. R. Tannenbaum T. P. Labuza

1968-01-01

145

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

146

Inhibitory effect of metal ions on alkaline mesentericopeptidase.  

PubMed

The effect of AG+, Cu2+, Cd2+, Co2+ and Ni2+ on the activity of alkaline mesentericopeptidase (EC 3.4.21.-) has been studied. Ag+, Cu2+ and Cd2+ were found to be reversible non-competitive inhibitors of the enzyme. The pH-dependence of Ki for Ag+-inhibition is sigmoidal with a pKa near 6. The Kilim values, calculated for the pH-independent region of the metal-enzyme inhibition, are close to the corresponding dissociation constants of metal-imidazole complexes, thus implying that the inhibitory effect of metal ions on enzyme activity is due to complex formation with the imidazole group of the active site histidine. The method of the two-component inhibition showed that Cu2+ and Ag+ bind to the same ligand of the enzyme molecule. The addition of Cu2+ decreases the rate of deacylation of the hydrolysis of p-nitrophenyl valerate, catalyzed by alkaline mesentericopeptidase in contrast to alpha-chymotrypsin where the acylation step is affected. PMID:7016196

Raykova, D; Dorovska-Taran, V; Blagoev, B

1981-01-01

147

Hydrolysis of steam-pretreated lignocellulose  

Microsoft Academic Search

The mechanism of hydrolysis of cellulose is important for improving the enzymatic conversion in bioprocesses based on lignocellulose.\\u000a Adsorption and hydrolysis experiments were performed with cellobiohydrolase I (CBH I) and endoglucanase II (EG II) from Trichoderma reesei on a realistic lignocellulose substrates: steam-pretreated willow. The enzymes were studied both alone and in equimolar mixtures.\\u000a Adsorption isotherms were determined at 4

Johan Karlsson; József Medve; Folke Tjerneld

1999-01-01

148

The complete enzymic hydrolysis of crosslinked proteins.  

PubMed

Procedures used for the complete enzymic hydrolysis of proteins are reviewed. The successful application of complete enzymic hydrolysis in the detection of naturally occurring isopeptide crosslinks and various other types of chemically introduced crosslinks is described. The method may fail if the level of crosslinking is too high, or if crosslinking is accompanied by racemization. Although it is usual to cleave disulphide crosslinks prior to enzymic digestion, the necessity for this in all cases is questioned. PMID:906920

Milligan, B; Holt, L A

1977-01-01

149

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

150

Acid mediated hydrolysis of blueberry anthocyanins.  

PubMed

Acid mediated hydrolysis of anthocyanins was studied using capillary zone electrophoresis (CZE). A commercially available wild blueberry (Bilberry) extract was dissolved in different concentrations of TFA (0.1, 1, 3, 9%), then was subjected to thermodecomposition reaction at 95 degrees C. After the reaction, the samples were analyzed by CZE. The hydrolysis rate of each anthocyanin and the formation of the aglycon were determined by the change in the peak pattern of the anthocyanins in the electropherogram. Each anthocyanin peak decreased time dependently in a first order kinetic fashion. It was revealed that the hydrolysis rate of each anthocyanin was determined primarily by the type of conjugated sugar and not by the aglycon structure. The rate constant of anthocyanin hydrolysis was in the following order, arabinoside>galactoside>glucoside without regard to the aglycon structure. The kinetic behavior of this anthocyanin hydrolysis together with the CZE mobility allowed us to identify an unknown CZE peak as delphinidin 3-O-beta-arabinoside. At low TFA concentration, significant decomposition of the anthocyanidin nucleus occurred, but the glycoside hydrolysis predominated at high TFA concentration. It was further revealed that the aglycon released reacted successively to form polymeric products at higher TFA conditions. PMID:11201215

Ichiyanagi, T; Oikawa, K; Tateyama, C; Konishi, T

2001-01-01

151

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

152

A water-insoluble (1?3)-?- d-glucan from the alkaline extract of an edible mushroom Termitomyces eurhizus  

Microsoft Academic Search

A water-insoluble glucan, TEINS has been isolated from the hot alkaline extract of an edible mushroom Termitomyces eurhizus. The total carbohydrate content of the polysaccharide fraction was found to be 98.4%, and it was found to contain only glucose as the monosaccharide constituent. On the basis of total acid hydrolysis, a methylation experiment, periodate oxidation and 13C NMR experiment, the

Indranil Chakraborty; Soumitra Mondal; Dilip Rout; Syed S. Islam

2006-01-01

153

Enzymatic saccharification of pretreated wheat straw: comparison of solids-recycling, sequential hydrolysis and batch hydrolysis.  

PubMed

In the enzymatic hydrolysis of lignocellulose materials, the recycling of the solid residue has previously been considered within the context of enzyme recycling. In this study, a steady state investigation of a solids-recycling process was made with pretreated wheat straw and compared to sequential and batch hydrolysis at constant reaction times, substrate feed and liquid and enzyme consumption. Compared to batch hydrolysis, the recycling and sequential processes showed roughly equal hydrolysis yields, while the volumetric productivity was significantly increased. In the 72h process the improvement was 90% due to an increased reaction consistency, while the solids feed was 16% of the total process constituents. The improvement resulted primarily from product removal, which was equally efficient in solids-recycling and sequential hydrolysis processes. No evidence of accumulation of enzymes beyond the accumulation of the substrate was found in recycling. A mathematical model of solids-recycling was constructed, based on a geometrical series. PMID:24333697

Pihlajaniemi, Ville; Sipponen, Satu; Sipponen, Mika H; Pastinen, Ossi; Laakso, Simo

2014-02-01

154

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

155

A simple spectrophotometric determination of meptyldinocap by its hydrolysis.  

PubMed

A simple spectrophotometric method is proposed for the determination of meptyldinocap (2,4-dinitro-6-octylphenyl crotonate). The method is based on the hydrolysis of meptyldinocap by hydroxylamine solution in alkaline medium to give 2,4-dinitro-6-octylphenol (2,4-DNOP), having maximum absorption at 380 nm. The reaction is found to be instantaneous in presence of ethanol. Beer's law is valid over the concentration range of 1.2-13 microg mL(-1) with molar absorptivity and Sandell's sensitivity of 3.22 x 10(6) L mol(-1) cm(-1) and 0.0001 microg cm(-2) respectively. The limit of detection and quantification were 0.0892 and 0.2703 microg mL(-1), respectively. The tolerance limits of interfering ions are discussed. All variables were studied in order to optimize the reaction conditions. The validity of the method was checked by its simultaneous determination in fruits and water samples and the results were statistically compared with those of a reference method by applying the Student's t-test and F-test. PMID:23841335

Kurup, Sunita; Pillai, Ajai Kumar

2013-01-01

156

Effects of acidity and alkalinity on the stability of amidohydrolases in freshwater  

Microsoft Academic Search

The influence of acidity and alkalinity on the enzymatic hydrolysis of amide-N in the aquatic system was investigated by determining the stability of L-asparaginase (EC (Enzyme Commission) 3.5.1.1), L-glutaminase (EC 3.5.1.2), and amidase (EC 3.5.1.4), and urease (EC 3.5.1.5) with respect to pH in three freshwater lakes. The water samples were first incubated at the indicated buffer pH (1-13) for

W. T. Jr. Frankenberger; A. L. Page

1983-01-01

157

Hydrolysis and heat treatment of aluminum dust.  

PubMed

Aluminum dust is a toxic and hazardous byproduct of Al remelting. The present research was performed to characterize and evaluate its behavior in water. The materials obtained by hydrolysis were also characterized, and the gases generated during the process were qualitatively analyzed. The effects of hydrolysis reaction time and temperature on the dust were also explored. The hydrolysis of Al dust is an exothermic reaction that gave rise to a solid composed of aluminum oxide, silicon oxide, and spinel (MgAl2O4). Most of the CH4, NH3, and SH2 gases generated were emitted immediately upon the start of the reaction, though their production continued for a long time. This slow reaction, which was moderately accelerated by temperature, led to the formation of a material less reactive than the untreated dust. On the other hand, heat treatment of the dust gave rise to an inert material composed of spinel, alumina, and magnesium and aluminum silicates. PMID:11417682

López, F A; Peña, M C; López-Delgado, A

2001-06-01

158

Alkaline and alkaline earth metal phosphate halides and phosphors  

DOEpatents

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

159

Hydrolysis of iodine: equilibria at high temperatures  

SciTech Connect

The hydrolysis (or disproportionation) of molecular iodine to form iodate and iodide ions has been studied by emf measurements over the temperature range, 3.8/sup 0/ to 209.0/sup 0/C. The interpretation of these results required a knowledge of the formation constant for triiodide ion and the acid dissociation constant of iodic acid, both of which were measured as a function of temperature. The resulting thermodynamic data have been incorporated into a general computer model describing the hydrolysis equilibria of iodine as a function of initial concentration, pH and temperature.

Palmer, D.A.; Ramette, R.W.; Mesmer, R.E.

1984-01-01

160

[Degradation of nicosulfuron by combination effects of microorganisms and chemical hydrolysis].  

PubMed

A strain which was capable of degrading nicosulfuron in the presence of glucose was isolated from nicosulfuron contaminated wetland soil, and it was identified as Klebsiella sp. based on 16S rDNA gene sequencing analysis. The strain could grow using nicosulfuron as the sole nitrogen source. The optimal temperature was 35 degrees C and the initial pH was neutral to weak acid. Hydrolysis experiments indicated that nicosulfuron remained stably under neutral and alkaline conditions, while in acidic conditions, it hydrolyzed quickly. Based on biodegradation experiments, when the concentration of glucose in culture was 5 g x L(-1), the strain could degrade 99.4% of nicosulfuron after incubation for 10 days at 35 degrees C, initial pH = 7; pH of the solution decreased from initial 7.0 to 4.0 in the meantime. When the concentration of glucose in culture solution was decreased to 500 mg x L(-1) and 100 mg x L(-1), with other conditions unchanged, only 11.7% and 6.6% of nicosulfuron were degraded, respectively, and pH of the solution remained at around 7.0. It was proposed that the degradation of nicosulfuron was caused by hydrolysis under acidic conditions at low pH which was resulted from the biodegradation of glucose by the strain. Therefore, the removal of nicosulfuron was actually caused by combined effects of microorganisms and chemical hydrolysis. PMID:24028028

Zhang, Xiao-Lin; Li, Yong-Mei; Yuan, Zhi-Wen

2013-07-01

161

Analysis of phenolic compounds in Portuguese wild and commercial berries after multienzyme hydrolysis.  

PubMed

Berry fruits are a good source of phenolic compounds and thus, potentially beneficial to health. Phenolic compounds are mainly present as a variety of conjugated forms, either with sugars via O-glycosidic bonds or with other polyols as esters. This chemodiversity makes characterization and identification highly demanding. Selected varieties of commercial blueberries, raspberries and blackberries and the two wild berries Portuguese crowberry and strawberry tree fruits were characterized for individual phenolic content by liquid chromatography-diode array detection and mass spectrometry (HPLC-DAD-MS) after hydrolysis by a novel combination of the fungal glycosidases hesperidinase and cellulase. This approach is shown to be a simple alternative to other existing methods for analysis of plant phenolic compound aglycones. The hydrolysis of glycosides and organic acid esters is efficient and less aggressive than acid and alkaline hydrolysis. This method is able to disclose new sources of dietary phenolic compounds, and the potential usefulness of Portuguese crowberry and strawberry tree fruit is herein demonstrated. PMID:23530973

Pimpão, Rui C; Dew, Tristan; Oliveira, Pedro B; Williamson, Gary; Ferreira, Ricardo B; Santos, Claudia N

2013-05-01

162

Alkaline Phosphatase and Other Hydrolyases Produced by Cenococcum graniforme, an Ectomycorrhizal Fungus  

PubMed Central

Cell extracts of Cenococcum graniforme have been found to contain the following hydrolytic enzymes: protease, esterase, ?-d-galactopyranosidase, ?-d-galactopyranosidase, ?-d-mannopyranosidase, ?-d-xylopyranosidase, ?-d-glucopyranosidase, ?-d-glucopyranosidase, and alkaline phosphatase. Sulfatase, inorganic pyrophosphatase, and ?-d-mannopyranosidase were not detected in the extracts. ?-d-Xylopyranosidase and ?-d-mannopyranosidase were most active in the neutral pH range, protease and phosphatase were most active in the alkaline pH range, and other enzymes were most active in the acidic pH range. These enzymes showed a high association with cell wall material, and the release of enzymes from the cells into the culture fluid appeared to occur only when the cells were undergoing autolysis. Alkaline phosphatase in C. graniforme is a constitutive enzyme, and examination of the alkaline phosphatase following a purification of 265-fold produced the following characteristics: pH optimum of 9.5, Mr of 60,000, Km of 2.1 × 10-4 M for p-nitrophenylphosphate, and activation energy for hydrolysis of the substrate at 9.9 kcal (1 cal = 4.184 J)/mol.

Bae, Kwang-Sung; Barton, Larry L.

1989-01-01

163

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

164

Thioglycoside hydrolysis catalyzed by {beta}-glucosidase  

SciTech Connect

Sweet almond {beta}-glucosidase (EC 3.2.1.21) has been shown to have significant thioglycohydrolase activity. While the K{sub m} values for the S- and O-glycosides are similar, the k{sub cat} values are about 1000-times lower for the S-glycosides. Remarkably, the pH-profile for k{sub cat}/K{sub m} for hydrolysis of p-nitrophenyl thioglucoside (pNPSG) shows the identical dependence on a deprotonated carboxylate (pK{sub a} 4.5) and a protonated group (pK{sub a} 6.7) as does the pH-profile for hydrolysis of the corresponding O-glycoside. Not surprisingly, in spite of the requirement for the presence of this protonated group in catalytically active {beta}-glucosidase, thioglucoside hydrolysis does not involve general acid catalysis. There is no solvent kinetic isotope effect on the enzyme-catalyzed hydrolysis of pNPSG.

Shen Hong [Department of Chemistry, Tulane University, New Orleans, LA 70118 (United States); Byers, Larry D. [Department of Chemistry, Tulane University, New Orleans, LA 70118 (United States)], E-mail: byers@tulane.edu

2007-10-26

165

HD Hydrolysis/Biodegradation Toxicology and Kinetics.  

National Technical Information Service (NTIS)

One technology developed for potential use in the disposal of RD (2,2'-dichlorodiethyl sulfide) from the Aberdeen Proving Ground unitary chemical stockpile is hydrolysis followed by biodegradation. Stockpile RD (89.2% pure) was hydrolyzed in 90 deg C wate...

S. P. Harvey L. L. Szafraniec W. T. Beaudry M. V. Haley T. E. Rosso

1996-01-01

166

Hippurate Hydrolysis in Klebsiella-Cloaca Classification  

Microsoft Academic Search

SUMMARY: 169 strains of Klebsiella pneumoniae and 68 strains of Cloaca cloacae were used in an examination of Hajna & Damon's hippurate test and various modi- fications of it. The addition of a pH indicator (phenol red) to the medium enabled hydrolysis to be detected by a change of colour. Clear-cut distinction between K. pneumoniae and C. cloacae was not

MERIEL L. THIRST

1957-01-01

167

COMPUTERIZED EXTRAPOLATION OF HYDROLYSIS RATE DATA  

EPA Science Inventory

The program RATE was developed to aid in the extrapolation and interpretation of hydrolysis rate data to a format that is useful for environmental risk assessment. ydrolysis data typically are reported in the literature as pseudo-first-order rate constants at the temperature and ...

168

Microstructure of coke briquettes from hydrolysis lignin  

Microsoft Academic Search

The microstructure of pyrolyzed briquettes prepared from hydrolyzed lignins at different final heating temperatures has been investigated. The pore structure of the briquettes of hydrolysis lignins before the thermal treatment is dependent to a large extent upon the granulometric composition of the raw material. The initial structure of the lignins also played an important part on the effect of the

B. N. Zhitov; Yu. G. Korolev; G. N. Makarov; A. M. Myasoedov; I. A. Shimanskaya; V. P. Okladnikov

1984-01-01

169

Optimization of dilute acid hydrolysis of Enteromorpha  

NASA Astrophysics Data System (ADS)

Acid hydrolysis is a simple and direct way to hydrolyze polysaccharides in biomass into fermentable sugars. To produce fermentable sugars effectively and economically for fuel ethanol, we have investigated the hydrolysis of Enteromorpha using acids that are typically used to hydrolyze biomass: H2SO4, HCl, H3PO4 and C4H4O4 (maleic acid). 5%(w/w) Enteromorpha biomass was treated for different times (30, 60, and 90 min) and with different acid concentrations (0.6, 1.0, 1.4, 1.8, and 2.2%, w/w) at 121°C. H2SO4 was the most effective acid in this experiment. We then analyzed the hydrolysis process in H2SO4 in detail using high performance liquid chromatography. At a sulfuric acid concentration of 1.8% and treatment time of 60 min, the yield of ethanol fermentable sugars (glucose and xylose) was high, (230.5 mg/g dry biomass, comprising 175.2 mg/g glucose and 55.3 mg/g xylose), with 48.6% of total reducing sugars being ethanol fermentable. Therefore, Enteromorpha could be a good candidate for production of fuel ethanol. In future work, the effects of temperature and biomass concentration on hydrolysis, and also the fermentation of the hydrolysates to ethanol fuel should be focused on.

Feng, Dawei; Liu, Haiyan; Li, Fuchao; Jiang, Peng; Qin, Song

2011-11-01

170

Mechanisms of lactone hydrolysis in acidic conditions.  

PubMed

The acid-catalyzed hydrolysis of linear esters and lactones was studied using a hybrid supermolecule-polarizable continuum model (PCM) approach including up to six water molecules. The compounds studied included two linear esters, four ?-lactones, two ?-lactones, and one ?-lactone: ethyl acetate, methyl formate, ?-propiolactone, ?-butyrolactone, ?-isovalerolactone, diketene (4-methyleneoxetan-2-one), ?-butyrolactone, 2(5H)-furanone, and ?-valerolactone. The theoretical results are in good quantitative agreement with the experimental measurements reported in the literature and also in excellent qualitative agreement with long-held views regarding the nature of the hydrolysis mechanisms at molecular level. The present results help to understand the balance between the unimolecular (A(AC)1) and bimolecular (A(AC)2) reaction pathways. In contrast to the experimental setting, where one of the two branches is often occluded by the requirement of rather extreme experimental conditions, we have been able to estimate both contributions for all the compounds studied and found that a transition from A(AC)2 to A(AC)1 hydrolysis takes place as acidity increases. A parallel work addresses the neutral and base-catalyzed hydrolysis of lactones. PMID:23731203

Gómez-Bombarelli, Rafael; Calle, Emilio; Casado, Julio

2013-07-19

171

Monitoring enzymatic ATP hydrolysis by EPR spectroscopy.  

PubMed

An adenosine triphosphate (ATP) analogue modified with two nitroxide radicals is developed and employed to study its enzymatic hydrolysis by electron paramagnetic resonance spectroscopy. For this application, we demonstrate that EPR holds the potential to complement fluorogenic substrate analogues in monitoring enzymatic activity. PMID:24872080

Hacker, Stephan M; Hintze, Christian; Marx, Andreas; Drescher, Malte

2014-06-12

172

Hydrolysis of ionic cellulose to glucose.  

PubMed

Hydrolysis of ionic cellulose (IC), 1,3-dimethylimidazolium cellulose phosphite, which could be synthesized from cellulose and dimethylimidazolium methylphosphite ([Dmim][(OCH3)(H)PO2]) ionic liquid, was conducted for the synthesis of glucose. The reaction without catalysts at 150°C for 12h produced glucose with 14.6% yield. To increase the hydrolysis yield, various acid catalysts were used, in which the sulfonated active carbon (AC-SO3H) performed the best catalytic activity in the IC hydrolysis. In the presence of AC-SO3H, the yields of glucose reached 42.4% and 53.9% at the reaction condition of 150°C for 12h and 180°C for 1.5h, respectively; however the yield decreased with longer reaction time due to the degradation of glucose. Consecutive catalyst reuse experiments on the IC hydrolysis demonstrated the catalytic activity of AC-SO3H persisted at least through four successive uses. PMID:25011079

Vo, Huyen Thanh; Widyaya, Vania Tanda; Jae, Jungho; Kim, Hoon Sik; Lee, Hyunjoo

2014-09-01

173

Hydrolysis of glycocholic acid by fungi  

Microsoft Academic Search

A range of fungi have been investigated for their ability to hydrolyse glycocholic acid to yield cholic acid. Using thin-layer chromatography the majority of fungi tested have been shown to possess this ability. In the case of Cochliobolus intermedius IMI 52980 the product of hydrolysis has been isolated and characterised as cholic acid. The same organism has been demonstrated to

I. So Maddox; R. Chong

1978-01-01

174

Zinc-air alkaline batteries - A review  

NASA Astrophysics Data System (ADS)

The basic principles involved in the operation of an alkaline zinc-air system are considered. Fully developed primary and mechanically rechargeable cells and their applications are reviewed. Various obstacles pertaining to the development of an electrically rechargeable zinc-air alkaline battery and possible means of overcoming them to some degree are summarized.

Chakkaravarthy, C.; Waheed, A. K. A.; Udupa, H. V. K.

1981-07-01

175

Alkaline hydrogen peroxide bleaching of cellulose  

Microsoft Academic Search

A closed system bleaching apparatus was designed to determine the kinetics and effects of various factors on alkaline hydrogen peroxide bleaching of textile cellulose fabrics. It was confirmed that perhydroxyl anion is the primary bleaching moiety in alkaline hydrogen peroxide systems. The use of the apparatus in the measurement of fabric color, waste oxygen, and the subsequent calculation of hydroxyl

Robert E. Brooks; Samuel B. Moore

2000-01-01

176

Facile chemiluminescent method for alkaline phosphatase determination  

Microsoft Academic Search

The determination of alkaline phosphatase activity is of wide applicability, both as a free enzyme or bound to antibodies (conjugates). Activity determinations employing chemiluminescent substrates have become increasingly important due to their high sensitivity, typically equivalent to or better than assays utilizing radioactive labels. We report here a new chemiluminescent methodology for the determination of alkaline phosphatase activity based on

Valdecir F. Ximenes; Ana Campa; Wilhelm J. Baader; Luiz H. Catalani

1999-01-01

177

Kinetic Study of Hydrolysis of Polyester Elastomer in Magnetic Tape.  

National Technical Information Service (NTIS)

A useful method for kinetic study of the hydrolysis of polyester elastomer is established which uses the number-average molecular weight. The reasonableness of this method is confirmed and the effect of magnetic particles on hydrolysis is considered.

K. Yamamoto H. Watanabe

1994-01-01

178

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 ...

179

Evolution of alkaline phosphatases in primates.  

PubMed Central

Alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] in placenta, intestine, liver, kidney, bone, and lung from a variety of primate species has been characterized by quantitative inhibition, thermostability, and immunological studies. Characteristic human placental-type alkaline phosphatase occurs in placentas of great apes (chimpanzee and orangutan) but not in placentas of other primates, including gibbon. It is also present in trace amounts in human lung but not in lung or other tissues of various Old and New World monkeys. However, a distinctive alkaline phosphatase resembling it occurs in substantial amounts in lungs from Old World monkeys but not New World monkeys. It appears that duplication of alkaline phosphatase genes and mutations of genetic elements controlling their tissue expression have occurred relatively recently in mammalian evolution. Images

Goldstein, D J; Rogers, C; Harris, H

1982-01-01

180

Compound and enzyme-specific phosphodiester hydrolysis mechanisms revealed by ? 18O of dissolved inorganic phosphate: Implications for marine P cycling  

Microsoft Academic Search

We have studied the oxygen isotope signature of inorganic phosphate (Pi) 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 Pi for a total of two

Yuhong Liang; Ruth E. Blake

2009-01-01

181

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

182

Ball milling pretreatment of corn stover for enhancing the efficiency of enzymatic hydrolysis.  

PubMed

Ethanol can be produced from lignocellulosic biomass with the usage of ball milling pretreatment followed by enzymatic hydrolysis and fermentation. The sugar yields from lignocellulosic feed stocks are critical parameters for ethanol production process. The research results from this paper indicated that the yields of glucose and xylose were improved by adding any of the following dilute chemical reagents: H(2)SO(4), HCl, HNO(3), CH(3)COOH, HCOOH, H(3)PO(4), and NaOH, KOH, Ca(OH)(2), NH(3)·H(2)O in the ball milling pretreatment of corn stover. The optimal enzymatic hydrolysis efficiencies were obtained under the conditions of ball milling in the alkali medium that was due to delignification. The data also demonstrated that ball milling pretreatment was a robust process. From the microscope image of ball milling-pretreated corn stover, it could be observed that the particle size of material was decreased and the fiber structure was more loosely organized. Meanwhile, the results indicate that the treatment effect of wet milling is better than that of dry milling. The optimum parameters for the milling process were ball speed of 350 r/min, solid/liquid ratio of 1:10, raw material particle size with 0.5 mm, and number of balls of 20 (steel ball, ??=?10 mm), grinding for 30 min. In comparison with water milling process, alkaline milling treatment could increase the enzymatic hydrolysis efficiency of corn stover by 110%; and through the digestion process with the combination of xylanase and cellulase mixture, the hydrolysis efficiency could increase by 160%. PMID:20593309

Lin, Zengxiang; Huang, He; Zhang, Hongman; Zhang, Lin; Yan, Lishi; Chen, Jingwen

2010-11-01

183

Removing Hemicellulose from Pulps by Specific Enzymic Hydrolysis  

Microsoft Academic Search

The hemicellulose content (solubility in 18% NaOH) of a delignified mechanical aspen pulp was lowered from 23.4% to 18.2% by one-hour hydrolysis with xylanase isolated from the fungus Schizophpllum commune by fractional precipitation. After 24 h hydrolysis, the hemicellulose content was reduced further to 12.9%. The predominant hydrolysis products, xylose and xylobiose, confirmed the specificity of hydrolysis. A crude mixture

M. G. Paice; L. Jurasek

1984-01-01

184

Enzymatic hydrolysis of rawhide using papain and neutrase  

Microsoft Academic Search

Rawhide split was hydrolysed separately by two proteolytic enzymes, papain and neutrase. The effects of enzymatic conditions of the hydrolysis reaction were investigated. During the first 10min of the enzymatic hydrolysis, the yield of the hydrolysed protein increased sharply, then it slowly increased or became essentially constant due to the limited availability of the substrate. The optimum hydrolysis conditions of

Siriporn Damrongsakkul; Kongpob Ratanathammapan; Kittinan Komolpis; Wiwut Tanthapanichakoon

2008-01-01

185

Technical bases for precipitate hydrolysis process operating parameters  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for precipitate hydrolysis specified in WSRC-RP-92737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF).

Bannochie, C.J.

1992-10-05

186

Enhanced enzymatic hydrolysis of palm pressed fiber based on the three main components: cellulose, hemicellulose, and lignin.  

PubMed

The enzymatic hydrolysis of the native and the pretreated palm pressed fiber (PPF) was deeply investigated by using the enzyme cocktail ACCELLERASE 1500. Together with the spent PPF from the first hydrolysis and the further doubly-treated PPF, the proportions of three main components were determined and analyzed based on a triangle figure. The proportion (cellulose/hemicelluloses/lignin) in the spent PPF was equal to 44:23:33 and the surface morphology of the spent PPF looks very similar to the native PPF surface showing poor hydrolysis efficiency. After further double treatment, the proportion was changed evidently from the original 44:23:33 to 54:21:25 and the surface structure was significantly disrupted showing a potential to be hydrolyzed completely. Additionally, all samples were characterized by Fourier transform infrared spectroscopy and X-ray diffractogram through considerations of alkaline solution treatment, so as to understand better the nature of biomass hydrolysis, from the aspect of three biomass components. PMID:24652599

Lin, Lili; Yan, Rong; Jiang, Wenju; Shen, Fei; Zhang, Xiaohong; Zhang, Yanzong; Deng, Shihuan; Li, Zhuang

2014-05-01

187

In-depth investigation of enzymatic hydrolysis of biomass wastes based on three major components: Cellulose, hemicellulose and lignin.  

PubMed

The artificial biomass based on three biomass components (cellulose, hemicellulose and lignin) were developed on the basis of a simplex-lattice approach. Together with a natural biomass sample, they were employed in enzymatic hydrolysis researches. Different enzyme combines of two commercial enzymes (ACCELLERASE 1500 and OPTIMASH BG) showed a potential to hydrolyze hemicellulose completely. Negligible interactions among the three components were observed, and the used enzyme ACCELLERASE 1500 was proven to be weak lignin-binding. On this basis, a multiple linear-regression equation was established for predicting the reducing sugar yield based on the component proportions in a biomass. The hemicellulose and cellulose in a biomass sample were found to have different contributions in staged hydrolysis at different time periods. Furthermore, the hydrolysis of rice straw was conducted to validate the computation approach through considerations of alkaline solution pretreatment and combined enzymes function, so as to understand better the nature of biomass hydrolysis, from the aspect of three biomass components. PMID:20639116

Lin, Lili; Yan, Rong; Liu, Yongqiang; Jiang, Wenju

2010-11-01

188

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

189

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

190

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

191

Continuous steam hydrolysis of tulip poplar  

SciTech Connect

To produce ethanol from hardwood it is desirable to fractionate the hardwood in order to produce a relatively pure cellulosic pulp for dilute acid hydrolysis. An experimental investigation of continuous steam hydrolysis of tulip poplar wood chips indicates that over 90% of the lignin present can be extracted by 0.1N sodium hydroxide, resulting in a cellulose pulp containing over 90% hexosan. The study was performed using a Stake Technology, Ltd., continuous digester rated at one oven dry ton per hour of wood chips. The yields of hexosans, hexoses, xylan, xylose, lignin, furfural, acetic acid and methanol were determined as a function of residence time and steam pressure in the digester. The information provides a basis for establishing a material and energy balance for a hardwood to ethanol plant.

Fieber, C.; Colcord, A.R.; Faass, S.; Muzzy, J.D.; Roberts, R.S.

1982-08-01

192

Enzymatic hydrolysis of rice dreg protein: Effects of enzyme type on the functional properties and antioxidant activities of recovered proteins.  

PubMed

The effects of various proteases on the formation and characteristics of rice dreg protein hydrolysates (RDPHs) were investigated. Enzymatic hydrolysis of often under-utilised rice dreg protein (RDP) with different enzymes studied here was found to significantly improve protein content and solubility. RDPHs prepared by alkaline protease showed better protein recovery, producing higher protein content with much smaller peptides, while hydrolysates generated by Protamex showed the highest antioxidant activities with more than 80% solubility over a wide pH range. The results indicated that the type of protease greatly influenced the molecular weight and amino acid residue composition of RDPH. The enzyme type also determined the functional properties and antioxidant activity of the recovered proteins. It was found that an optimum allocation of alkaline protease in addition to the Neutrase enzyme could be an appropriate strategy to produce RDPH with desirable functionalities, antioxidant properties, and low salt content. PMID:25005954

Zhao, Qiang; Xiong, Hua; Selomulya, Cordelia; Chen, Xiao Dong; Zhong, Honglan; Wang, Shenqi; Sun, Wenjing; Zhou, Qiang

2012-10-01

193

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

194

Mercerization and acid hydrolysis of bacterial cellulose  

Microsoft Academic Search

Structural changes in never- dried, disintegrated bacteria l cellulose by treatment with aqueous NaOH were examined by electron microscopy, X-ray diffractometry and acid hydrolysis behaviour and compared with those of cotton cellulose. The microfibril kept its fibrillar morphology after treatment with NaOH solutions of less than 9% (w\\/w), but changed into irregular aggregates when treated with NaOH above 12% (w\\/w),

HIDEKI Shibazaki; SHIGENORI Kuga; TAKESHI Okano

1997-01-01

195

?-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.

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

2013-01-01

196

Structural and biochemical characterization of a halophilic archaeal alkaline phosphatase.  

PubMed

Phosphate is an essential component of all cells that must be taken up from the environment. Prokaryotes commonly secrete alkaline phosphatases (APs) to recruit phosphate from organic compounds by hydrolysis. In this study, the AP from Halobacterium salinarum, an archaeon that lives in a saturated salt environment, has been functionally and structurally characterized. The core fold and the active-site architecture of the H. salinarum enzyme are similar to other AP structures. These generally form dimers composed of dominant beta-sheet structures sandwiched by alpha-helices and have well-accessible active sites. The surface of the enzyme is predicted to be highly negatively charged, like other proteins of extreme halophiles. In addition to the conserved core, most APs contain a crown domain that strongly varies within species. In the H. salinarum AP, the crown domain is made of an acyl-carrier-protein-like fold. Different from other APs, it is not involved in dimer formation. We compare the archaeal AP with its bacterial and eukaryotic counterparts, and we focus on the role of crown domains in enhancing protein stability, regulating enzyme function, and guiding phosphoesters into the active-site funnel. PMID:20438737

Wende, Andy; Johansson, Patrik; Vollrath, Ronnald; Dyall-Smith, Mike; Oesterhelt, Dieter; Grininger, Martin

2010-07-01

197

Thiogalactopyranosides are resistant to hydrolysis by ?-galactosidases.  

PubMed

Fluorescently tagged glycosides containing terminal ?(1?3) and ?(1?4)-linked thiogalactopyranosides have been prepared and tested for resistance to hydrolysis by ?-galactosidases. Eight fluorescent glycosides containing either galactose or 5-thiogalactose as the terminal sugar were enzymatically synthesized using galactosyltransferases, with lactosyl glycosides as acceptors and UDP-galactose or UDP-5'-thiogalactose, respectively, as donors. The glycosides were incubated with human ?-galactosidase A (CAZy family GH27, a retaining glycosidase), Bacteroides fragilis ?-1,3-galactosidase (GH110, an inverting glycosidase), or homogenates of MCF-7 human breast cancer cells or NG108-15 rat glioma cells. Substrate hydrolysis was monitored by capillary electrophoresis with fluorescence detection. All compounds containing terminal O-galactose were readily degraded. Their 5-thiogalactose counterparts were resistant to hydrolysis by human ?-galactosidase A and the enzymes present in the cell extracts. B. fragilis ?-1,3-galactosidase hydrolyzed both thio- and O-galactoside substrates; however, the thiogalactosides were hydrolyzed at only 1-3 % of the rate of O-galactosides. The hydrolytic resistance of 5-thiogalactose was also confirmed by an in vivo study using cells in culture. The results suggest that 5-thiogalactosides may be useful tools for the study of anabolic pathways in cell extracts or in single cells. PMID:22740420

Adlercreutz, Dietlind; Yoshimura, Yayoi; Mannerstedt, Karin; Wakarchuk, Warren W; Bennett, Eric P; Dovichi, Norman J; Hindsgaul, Ole; Palcic, Monica M

2012-07-23

198

Palm date fibers: analysis and enzymatic hydrolysis.  

PubMed

Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin) settled easily, while the low-lignin fibers (41.4% lignin) formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes. PMID:21151438

Shafiei, Marzieh; Karimi, Keikhosro; Taherzadeh, Mohammad J

2010-01-01

199

Structural basis unifying diverse GTP hydrolysis mechanisms.  

PubMed

Central to biological processes is the regulation rendered by GTPases. Until recently, the GTP hydrolysis mechanism, exemplified by Ras-family (and G-?) GTPases, was thought to be universal. This mechanism utilizes a conserved catalytic Gln supplied "in cis" from the GTPase and an arginine finger "in trans" from a GAP (GTPase activating protein) to stabilize the transition state. However, intriguingly different mechanisms are operative in structurally similar GTPases. MnmE and dynamin like cation-dependent GTPases lack the catalytic Gln and instead employ a Glu/Asp/Ser situated elsewhere and in place of the arginine finger use a K(+) or Na(+) ion. In contrast, Rab33 possesses the Gln but does not utilize it for catalysis; instead, the GAP supplies both a catalytic Gln and an arginine finger in trans. Deciphering the underlying principles that unify seemingly unrelated mechanisms is central to understanding how diverse mechanisms evolve. Here, we recognize that steric hindrance between active site residues is a criterion governing the mechanism employed by a given GTPase. The Arf-ArfGAP structure is testimony to this concept of spatial (in)compatibility of active site residues. This understanding allows us to predict an as yet unreported hydrolysis mechanism and clarifies unexplained observations about catalysis by Rab11 and the need for HAS-GTPases to employ a different mechanism. This understanding would be valuable for experiments in which abolishing GTP hydrolysis or generating constitutively active forms of a GTPase is important. PMID:23293872

Anand, Baskaran; Majumdar, Soneya; Prakash, Balaji

2013-02-12

200

Sugarcane bagasse hydrolysis using yeast cellulolytic enzymes.  

PubMed

Ethanol fuel production from lignocellulosic biomass is emerging as one of the most important technologies for sustainable development. To use this biomass, it is necessary to circumvent the physical and chemical barriers presented by the cohesive combination of the main biomass components, which hinders the hydrolysis of cellulose and hemicellulose into fermentable sugars. This study evaluated the hydrolytic capacity of enzymes produced by yeasts, isolated from the soils of the Brazilian Cerrado biome (savannah) and the Amazon region, on sugarcane bagasse pre-treated with H2SO4. Among the 103 and 214 yeast isolates from the Minas Gerais Cerrado and the Amazon regions, 18 (17.47%) and 11 (5.14%) isolates, respectively, were cellulase-producing. Cryptococcus laurentii was prevalent and produced significant ?- glucosidase levels, which were higher than the endo- and exoglucanase activities. In natura sugarcane bagasse was pre-treated with 2% H2SO4 for 30 min at 150oC. Subsequently, the obtained fibrous residue was subjected to hydrolysis using the Cryptococcus laurentii yeast enzyme extract for 72 h. This enzyme extract promoted the conversion of approximately 32% of the cellulose, of which 2.4% was glucose, after the enzymatic hydrolysis reaction, suggesting that C. laurentii is a good ?-glucosidase producer. The results presented in this study highlight the importance of isolating microbial strains that produce enzymes of biotechnological interest, given their extensive application in biofuel production. PMID:23851270

Souza, Angelica Cristina de; Carvalho, Fernanda Paula; Silva e Batista, Cristina Ferreira; Schwan, Rosane Freitas; Dias, Disney Ribeiro

2013-10-28

201

Palm Date Fibers: Analysis and Enzymatic Hydrolysis  

PubMed Central

Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin) settled easily, while the low-lignin fibers (41.4% lignin) formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes.

Shafiei, Marzieh; Karimi, Keikhosro; Taherzadeh, Mohammad J.

2010-01-01

202

Fungal secretomes enhance sugar beet pulp hydrolysis.  

PubMed

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

2014-04-01

203

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

204

Performed surfactant-optimized aqueous alkaline flood  

SciTech Connect

This paper describes improvement in a process for recovering oil from an acidic oil reservoir by injecting an aqueous alkaline solution comprising water, sodium chloride, and alkaline material for reacting with the reservoir oil forming a petroleum acid soap to form an in-situ surfactant system. The improvement comprises: selecting a preformed cosurfactant which is soluble in both the aqueous solution and the reservoir oil and has a solubility ratio which is grater than the solubility ratio of the petroleum acid soap where the solubility ratio is the ratio of solubility in the aqueous alkaline solution to the solubility in the reservoir oil; combining with the alkaline solution an amount of the preformed cosurfactant which will result in the in-situ surfacant system having a salinity about equal to a salinity which results in minimal interfacial tension between the oil in the reservoir and the in-situ surfactant system at reservoir temperature, wherein the amount of the preformed cosurfactant is about 0.3 percent by weight in the aqueous alkaline solution; and injecting the cosurfactant-aqueous alkaline solution mixture into the reservoir to displace oil toward a fluid production location.

Thigpen, D.R.; Lawson, J.B.; Nelson, R.C.

1991-11-26

205

A water-insoluble (1-->3)-beta-D-glucan from the alkaline extract of an edible mushroom Termitomyces eurhizus.  

PubMed

A water-insoluble glucan, TEINS has been isolated from the hot alkaline extract of an edible mushroom Termitomyces eurhizus. The total carbohydrate content of the polysaccharide fraction was found to be 98.4%, and it was found to contain only glucose as the monosaccharide constituent. On the basis of total acid hydrolysis, a methylation experiment, periodate oxidation and (13)C NMR experiment, the repeating unit of the polysaccharide was established as: -->3)-beta-D-Glcp-(1-->. PMID:17064674

Chakraborty, Indranil; Mondal, Soumitra; Rout, Dilip; Islam, Syed S

2006-12-29

206

Lactic acid production from lime-treated wheat straw by Bacillus coagulans : neutralization of acid by fed-batch addition of alkaline substrate  

Microsoft Academic Search

Conventional processes for lignocellulose-to-organic acid conversion requires pretreatment, enzymatic hydrolysis, and microbial\\u000a fermentation. In this study, lime-treated wheat straw was hydrolyzed and fermented simultaneously to lactic acid by an enzyme\\u000a preparation and Bacillus coagulans DSM 2314. Decrease in pH because of lactic acid formation was partially adjusted by automatic addition of the alkaline substrate.\\u000a After 55 h of incubation, the polymeric

Ronald H. W. Maas; Robert R. Bakker; Mickel L. A. Jansen; Diana Visser; Ed de Jong; Gerrit Eggink; Ruud A. Weusthuis

2008-01-01

207

Developmental Transition from Enzymatic to Acid Hydrolysis of Sucrose in Acid Limes (Citrus aurantifolia).  

PubMed

The sucrose breakdown mechanisms in juice sacs of acid lime (Citrus aurantifolia [Christm.] Swing.) were investigated throughout fruit development. All three enzymes of sucrose catabolism (sucrose synthase, acid, and alkaline invertase) are present during the initial stages. The activities of these enzymes declined rapidly and disappeared by stage 5 (80% development) but not before vacuolar pH had decreased to approximately 2.5. At this stage, sucrose breakdown occurs by acid hydrolysis. By attaining a vacuolar pH of 2.5 prior to enzyme disappearance, the cell maintains a continuous ability to break down sucrose throughout ontogeny. Thus, acid limes possess a unique and coordinated system for sucrose breakdown that involves both enzymatic and nonenzymatic pathways. PMID:16667241

Echeverria, E

1990-01-01

208

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

209

Two-stage alkaline-enzymatic pretreatments to enhance biohydrogen production from sunflower stalks.  

PubMed

Because of their rich composition in carbohydrates, lignocellulosic residues represent an interesting source of biomass to produce biohydrogen by dark fermentation. Nevertheless, pretreatments should be applied to enhance the solubilization of holocelluloses and increase their further conversion into biohydrogen. The aim of this study was to investigate the effect of thermo-alkaline pretreatment alone and combined with enzymatic hydrolysis to enhance biohydrogen production from sunflower stalks. A low increase of hydrogen potentials from 2.3 ± 0.9 to 4.4 ± 2.6 and 20.6 ± 5.6 mL of H2 g(-1) of volatile solids (VS) was observed with raw sunflower stalks and after thermo-alkaline pretreatment at 55 °C, 24 h, and 4% NaOH and 170 °C, 1 h, and 4% NaOH, respectively. Enzymatic pretreatment alone showed an enhancement of the biohydrogen yields to 30.4 mL of H2 g(-1) of initial VS, whereas it led to 49 and 59.5 mL of H2 g(-1) of initial VS when combined with alkaline pretreatment at 55 and 170 °C, respectively. Interestingly, a diauxic effect was observed with sequential consumption of sugars by the mixed cultures during dark fermentation. Glucose was first consumed, and once glucose was completely exhausted, xylose was used by the microorganisms, mainly related to Clostridium species. PMID:24053605

Monlau, Florian; Trably, Eric; Barakat, Abdellatif; Hamelin, Jérôme; Steyer, Jean-Philippe; Carrere, Hélène

2013-11-01

210

Human liver alkaline phosphatase purified by affinity chromatography, ultracentrifugation and polyacrylamide-gel electrophoresis.  

PubMed Central

A method is presented for the preparation of human liver alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1). The method gives a purification factor of 12.5 X 10(3) over the initial aq. butan-1-ol extract, a recovery of 6.0% and a specific activity for the preparation of 1450-1550 units/mg of protein, 1 unit being defined as the amount of enzyme catalysing the hydrolysis of 1mumol of p-nitrophenyl phosphate/min at 35 degrees C in 0.1 M-2-amino-2-methylpropan-1-ol/HCl buffer, pH 10.5, containing 10mM-p-nitrophenyl phosphate. Homogeneity was studied by ultracentrifugation, by immunoelectrophoresis and by polyacrylamide-gel electrophoresis. A single contaminating protein was present which was less than 5% of the total. Ultracentrifugation and equilibrium-gradient-pore electrophoresis techniques indicated a mol.wt. of 156000 and 160000 respectively. Equilibrium-gradient-pore electrophoresis indicated that the alkaline phosphatase molecule is possibly a dimer, comprising two subunits of about 80000 mol.wt. Amino acid analysis proved remarkably similar to that for alkaline phosphatase from other sources, regardless of species. Images PLATE 1

Latner, A L; Hodson, A W

1976-01-01

211

Synergy between cellulases and pectinases in the hydrolysis of hemp.  

PubMed

The impact of pectinases in the hydrolysis of fresh, steam-exploded and ensiled hemp was investigated and the synergy between cellulases, pectinases and xylanase in the hydrolysis was evaluated. About half; 59.3% and 46.1% of pectin in the steam-exploded and ensiled hemp, respectively, could be removed by a low dosage of pectinases used. Pectinases were more efficient than xylanase in the hydrolysis of fresh and ensiled hemp whereas xylanase showed higher hydrolytic efficiency than the pectinase preparation used in the hydrolysis of steam-exploded hemp. Clear synergistic action between cellulases and xylanase could be observed in the hydrolysis of steam-exploded hemp. Supplementation of pectinase resulted in clear synergism with cellulases in the hydrolysis of all hemp substrates. Highest hydrolysis yield of steam-exploded hemp was obtained in the hydrolysis with cellulases and xylanase. In the hydrolysis of ensiled hemp, the synergistic action between cellulases and pectinases was more obvious for efficient hydrolysis. PMID:23262004

Zhang, Junhua; Pakarinen, Annukka; Viikari, Liisa

2013-02-01

212

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

213

Hydrolysis of ferric chloride in solution  

SciTech Connect

The Detox{trademark} process uses concentrated ferric chloride and small amounts of catalysts to oxidize organic compounds. It is under consideration for oxidizing transuranic organic wastes. Although the solution is reused extensively, at some point it will reach the acceptable limit of radioactivity or maximum solubility of the radioisotopes. This solution could be cemented, but the volume would be increased substantially because of the poor compatibility of chlorides and cement. A process has been developed that recovers the chloride ions as HCl and either minimizes the volume of radioactive waste or permits recycling of the radioactive chlorides. The process involves a two-step hydrolysis at atmospheric pressure, or preferably under a slight vacuum, and relatively low temperature, about 200{degrees}C. During the first step of the process, hydrolysis occurs according to the reaction below: FeCl{sub 3 liquid} + H{sub 2}O {r_arrow} FeOCl{sub solid} + 2 HCl{sub gas} During the second step, the hot, solid, iron oxychloride is sprayed with water or placed in contact with steam, and hydrolysis proceeds to the iron oxide according to the following reaction: 2 FeOCl{sub solid} + H{sub 2}O {r_arrow} Fe{sub 2}O{sub 3 solid} + 2 HCl{sub gas}. The iron oxide, which contains radioisotopes, can then be disposed of by cementation or encapsulation. Alternately, these chlorides can be washed off of the solids and can then either be recycled or disposed of in some other way.

Lussiez, G.; Beckstead, L.

1996-11-01

214

[Immobilized glucoamylase: A biocatalyst of dextrin hydrolysis].  

PubMed

Heterogeneous biocatalysts of starch conversion based on glucoamylase and carbon-containing carriers were obtained, and their biocatalytic properties in enzymatic hydrolysis of corn dextrins were studied. It was shown that the morphology of the surface carbon layer of carriers markedly affected the properties of biocatalysts. Glucoamylase that was immobilized by adsorption on the surface of carriers covered with a layer of catalytic fibrous or pyrolytic carbon had the maximum enzymatic activity and stability, whereas the biocatalysts prepared on the basis of carriers that had no carbon layer or were covered with graphite-like surface carbon had a low activity and stability. PMID:16761568

Kovalenko, G A; Perminova, L V; Plaksin, G V; Chuenko, T V; Komova, O V; Rudina, N A

2006-01-01

215

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

216

Hydrolysis of olefin oxides to glycols  

SciTech Connect

A process is described for making 1,2-diols by the catalytic hydrolysis of an olefin oxide or a cyclo-olefin oxide, in the presence of water. The process comprises contacting the olefin oxide or a cyclo-olefin oxide of 2 to 20 carbon atoms with a catalyst comprising a silicate or zeolite. The silicate or zeolite, has a contraint index of about 1 to about 12, wherein the silicate or zeolite has an alpha value ranging from 1 to 500; and wherein the silicate or zeolite contains acidic hydrogen atoms.

Chang, C.D.; Hellring, S.D.

1986-10-28

217

Urea hydrolysis and calcium carbonate reaction fronts  

NASA Astrophysics Data System (ADS)

The mobility of toxic or radioactive metal contaminants in subsurface environments can be reduced by the formation of mineral precipitates that form co-precipitates with the contaminants or that isolate them from the mobile fluid phase. An engineering challenge is to control the spatial distribution of precipitation reactions with respect to: 1) the location of a contaminant, and 2) where reactants are introduced into the subsurface. One strategy being explored for immobilizing contaminants, such as Sr-90, involves stimulating mineral precipitation by forming carbonate ions and hydroxide via the in situ, microbially mediated hydrolysis of urea. A series of column experiments have been conducted to explore how the construction or design of such an in situ reactant production strategy can affect the temporal and spatial distribution of calcium carbonate precipitation, and how the distribution is coupled to changes in permeability. The columns were constructed with silica gel as the porous media. An interval midway through the column contained an adsorbed urease enzyme in order to simulate a biologically active zone. A series of influent solutions were injected to characterize hydraulic properties of the column (e.g., bromide tracer), profiles of chemical conditions and reaction products as the enzyme catalyzes urea hydrolysis (e.g., pH, ammonia, urea), and changes that occur due to CaCO3 precipitation with the introduction of a calcium+urea solutions. In one experiment, hydraulic conductivity was reduced as precipitate accumulated in a layer within the column that had a higher fraction of fine grained silica gel. Subsequent reduction of permeability and flow (for a constant head condition) resulted in displacement of the hydrolysis and precipitation reaction profiles upstream. In another experiment, which lacked the physical heterogeneity (fine grained layer), the precipitation reaction did not result in loss of permeability or flow velocity and the reaction profile, characterized by the pH profile and hydrolysis reaction species, was extended downstream of the enzyme zone. Downstream extension of the reaction profile was due partially to the partial mobility of the enzyme in the column. The experiments are helping to illustrate the complexity of transient reaction fronts as well as the needs and challenges for advanced modeling approaches. A modeling platform developed at the Idaho National Laboratory, which is capable of simulating tightly coupled physical-chemical processes (the Reactive Transport simulator), is being applied to pre-experimental simulations and post-experimental interpretation of results.

Fox, D. T.; Redden, G. D.; Henriksen, J.; Fujita, Y.; Guo, L.; Huang, H.

2010-12-01

218

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

219

A process for reduction in viscosity of coffee extract by enzymatic hydrolysis of mannan.  

PubMed

Mannan is the main polysaccharide component of coffee extract and is responsible for its high viscosity, which in turn negatively affects the technological processing involved in making instant coffee. In our study, we isolated mannan from coffee beans and extract of commercial coffee and it was enzymatically hydrolyzed using alkali-thermostable mannanase obtained from Bacillus nealsonii PN-11. As mannan is found to be more soluble under alkaline conditions, an alkali-thermostable mannanase is well suited for its hydrolysis. The process of enzymatic hydrolysis was optimized by response surface methodology. Under the following optimized conditions viz enzyme dose of 11.50 U mannanase g(-1) coffee extract, temperature of 44.50 °C and time of 35.80 min, significant twofold decrease in viscosity (50 mPas to 26.00 ± 1.56 mPas) was achieved. The application of this process in large-scale industrial production of coffee will help in reduction of energy consumption used during freeze-drying. It will also make technological processing involved in making coffee more economical. PMID:24390577

Chauhan, Prakram Singh; Sharma, Prince; Puri, Neena; Gupta, Naveen

2014-07-01

220

Xylan as limiting factor in enzymatic hydrolysis of nanocellulose.  

PubMed

The role of xylan as a limiting factor in the enzymatic hydrolysis of cellulose was studied by hydrolysing nanocellulose samples prepared by mechanical fibrillation of birch pulp with varying xylan content. Analyzing the nanocelluloses and their hydrolysis residues with dynamic FT-IR spectroscopy revealed that a certain fraction of xylan remained tightly attached to cellulose fibrils despite partial hydrolysis of xylan with xylanase prior to pulp fibrillation and that this fraction remained in the structure during the hydrolysis of nanocellulose with cellulase mixture as well. Thus, a loosely bound fraction of xylan was predicted to have been more likely removed by purified xylanase. The presence of loosely bound xylan seemed to limit the hydrolysis of crystalline cellulose, indicated by an increase in cellulose crystallinity and by preserved crystal width measured with wide-angle X-ray scattering. Removing loosely bound xylan led to a proportional hydrolysis of xylan and cellulose with the cellulase mixture. PMID:23238342

Penttilä, Paavo A; Várnai, Anikó; Pere, Jaakko; Tammelin, Tekla; Salmén, Lennart; Siika-aho, Matti; Viikari, Liisa; Serimaa, Ritva

2013-02-01

221

Surfactant-Enhanced Alkaline Flooding: Buffering at Intermediate Alkaline pH  

Microsoft Academic Search

The alkaline flooding process involves injecting alkaline agents into the reservoir to produce more oil than is produced through conventional waterflooding. The interaction of the alkali in the flood water with the naturally occurring acids in the reservoir oil results in in-situ formation of soaps, which are partially responsible for lowering IFT and improving oil recovery. The extent to which

Rudin Jeff; Darsh Wasan

1993-01-01

222

Generators of bioactive nanoaerosols of iodides, bromides, and chlorides of alkaline and alkaline-earth metals  

Microsoft Academic Search

Generators of bioactive nanoaerosols of alkaline and alkaline-earth metal halide salts with 0.005-to 0.5-µm particle sizes\\u000a and 0.5- to 50-µg\\/s mass output are described. The devices can be used in halatherapy and combat human iodine deficiency.

A. V. Zagnit’ko; A. N. Pershin; L. I. Ivanova; D. V. Grazhdankina; A. V. Svistel’nik

2010-01-01

223

Uptake of arsenic by alkaline soils near alkaline coal fly ash disposal facilities.  

PubMed

The attenuation of arsenic in groundwater near alkaline coal fly ash disposal facilities was evaluated by determining the uptake of arsenic from ash leachates by surrounding alkaline soils. Ten different alkaline soils near a retired coal fly ash impoundment were used in this study with pH ranging from 7.6 to 9.0, while representative coal fly ash samples from two different locations in the coal fly ash impoundment were used to produce two alkaline ash leachates with pH 7.4 and 8.2. The arsenic found in the ash leachates was present as arsenate [As(V)]. Adsorption isotherm experiments were carried out to determine the adsorption parameters required for predicting the uptake of arsenic from the ash leachates. For all soils and leachates, the adsorption of arsenic followed the Langmuir and Freundlich equations, indicative of the favorable adsorption of arsenic from leachates onto all soils. The uptake of arsenic was evaluated as a function of ash leachate characteristics and the soil components. The uptake of arsenic from alkaline ash leachates, which occurred mainly as calcium hydrogen arsenate, increased with increasing clay fraction of soil and with increasing soil organic matter of the alkaline soils. Appreciable uptake of arsenic from alkaline ash leachates with different pH and arsenic concentration was observed for the alkaline soils, thus attenuating the contamination of groundwater downstream of the retired coal fly ash impoundment. PMID:23877575

Khodadoust, Amid P; Theis, Thomas L; Murarka, Ishwar P; Naithani, Pratibha; Babaeivelni, Kamel

2013-12-01

224

Assessment of the hydrolysis process for the determination of okadaic acid-group toxin ester: presence of okadaic acid 7-O-acyl-ester derivates in Spanish shellfish.  

PubMed

The contamination of different types of shellfish by okadaic acid (OA)-group toxin esters is an important problem that presents serious risk for human health. During previous investigations carried out in our laboratory by liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS), the occurrence of a high percentage of esters in relation to the total OA equivalents has been observed in several shellfish species. The determination of these kinds of toxins using LC/MS or other chemical methods requires a hydrolysis step in order to convert the sterified compounds into the parent toxins, OA, dinophysistoxins-1 (DTX-1) and dinophysistoxins-2 (DTX-2). Most of the hydrolysis procedures are based on an alkaline hydrolysis reaction. However, despite hydrolysis being a critical step within the analysis, it has not been studied in depth up to now. The present paper reports the results obtained after evaluating the hydrolysis process of an esterified form of OA by using a standard of 7-O-acyl ester with palmitoyl as the fatty acid (palOA). Investigations were focused on checking the effectiveness of the hydrolysis for palOA using methanol as solvent standard and matrices matched standards. From the results obtained, no matrix influence on the hydrolysis process was observed and the quantity of palOA converted into OA was always above 80%. The analyses of different Spanish shellfish samples showed percentages of palOA in relation to the total OA esters ranging from 27% to 90%, depending on the shellfish specie. PMID:18243269

Villar-González, A; Rodríguez-Velasco, M L; Ben-Gigirey, B; Yasumoto, T; Botana, L M

2008-04-01

225

Starch hydrolysis modeling: application to fuel ethanol production  

Microsoft Academic Search

Efficiency of the starch hydrolysis in the dry grind corn process is a determining factor for overall conversion of starch\\u000a to ethanol. A model, based on a molecular approach, was developed to simulate structure and hydrolysis of starch. Starch structure\\u000a was modeled based on a cluster model of amylopectin. Enzymatic hydrolysis of amylose and amylopectin was modeled using a Monte

Ganti S. MurthyDavid; David B. Johnston; Kent D. Rausch; M. E. Tumbleson; Vijay Singh

226

Influence of relativistic effects on hydrolysis of Ra 2+  

Microsoft Academic Search

Summary  Using 224Ra radiotracer the first hydrolysis constant (pK1h) of Ra2+ cations has been determined. The pK1h value of Ra2+ was compared with the pK1h values of other Group 2 cations. It has been shown that the electrostatic hydrolysis model based on assumption that pK1h is a linear function of reciprocal ionic radii (1\\/ri) does not describe well the hydrolysis of

B. Zieli?ska; A. Bilewicz

2005-01-01

227

Technical bases for precipitate hydrolysis process operating parameters  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

Bannochie, C.J.; Lambert, D.P.

1992-11-09

228

Technical bases for precipitate hydrolysis process operating parameters. Revision 1  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

Bannochie, C.J.; Lambert, D.P.

1992-11-09

229

Enhanced hydrolysis resistance of biodegradable polymers and bio-composites  

Microsoft Academic Search

This study investigated the hydrolysis of biodegradable polymers and bio-composites at 50°C and 90% relative humidity (RH). With increasing hydrolysis time, the mechanical properties of the biodegradable polymers and bio-composites significantly decreased due to the easy hydrolytic degradation of the ester linkage of the biodegradable polymers. With increasing hydrolysis time, the tensile strength of the polybutylene succinate (PBS) treated with

Hee-Soo Kim; Hyun-Joong Kim

2008-01-01

230

Study of the conversion products of dipin in hydrochloric acid and alkaline media by TLC and mass spectrometry  

SciTech Connect

In an investigation of the metabolism of the antitumor preparation dipin(tetraethylenimide of 1,4-diperazinediphosphoric acid) the authors studied its conversion in hydrochloric acid and in alkaline media. The mass spectra of the isolated compounds are given. The chromatographic separation of dipin conversion products is presented. A check on the composition of the solutions was done by mass spectrometry and TLC. Dipin in hydrochloric acid medium is subject to conversion with the formation of products of addition of HCl at the ethylenimine groups with formation of a beta-chloroethylamine group and also of products of hydrolysis at P-N bonds.

Chistyakov, V.V.; Anisimova, O.S.; Sheinker, Yu.N.; Safonova, T.S.

1986-03-01

231

Studies on Cellulose Hydrolysis by Acetivibrio cellulolyticus†  

PubMed Central

Acetivibrio cellulolyticus extracellular cellulase extensively hydrolyzed crystalline celluloses such as Avicel (FMC Corp., Food and Pharmaceutical Products Div., Philadelphia, Pa.) but only if it was desalted and supplemented with Ca2+. The Ca2+ effect was one of increased enzyme stability in the presence of the ion. Although preincubation of the cellulase complex at 40°C for 5 h without added Ca2+ had a negligible effect on endoglucanase activity or on the subseqent hydrolysis of amorphous cellulose, the capacity of the enzyme to hydrolyze crystalline cellulose was almost completely lost. Adsorption studies showed that 90% of the Avicel-solubilizing component of the total enzyme preparation bound to 2% Avicel at 40°C. Under these conditions, only 15% of the endoglucanase and 25% of the protein present in the enzyme preparation adsorbed to the substrate. The protein profile of the bound enzyme, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was complex and distinctly different from the profile observed for total cellulase preparations. The specific activity of A. cellulolyticus cellulase with respect to Avicel hydrolysis was compared with that of commercially available Trichoderma reesei cellulase. Images

MacKenzie, C. Roger; Bilous, Doris; Patel, Girishchandra B.

1985-01-01

232

Immobilized protease on the magnetic nanoparticles used for the hydrolysis of rapeseed meals  

NASA Astrophysics Data System (ADS)

(3-aminopropl) triethoxysilaneand modified magnetic nanoparticles with the average diameter of 25.4 nm were synthesized in water-phase co-precipitation method. And then these nanoparticles were covalently coupled with alkaline protease as enzyme carrier by using 1,4-phenylene diisothlocyanate as coupling agent. Experiments showed that the immobilized protease can keep the catalytic bioactivity, which can reach to 47.8% when casein was served as substrate. Results showed that the catalytic activity of immobilized protease on these magnetic nanoparticles could retain 98.63±2.37% after 60 days. And it is more stable than the free protease during the shelf-life test. The enzyme reaction conditions such as optimum reaction temperature and pH are the same as free protease. Furthermore, mix-and-separate experiments showed that the immobilized protease could be recycled through the magnetic nanoparticles after the biocatalysis process. When the rapeseed meals were used as substrate, the degree of hydrolysis of immobilized alkaline protease achieved 9.86%, while it was 10.41% for the free protease. The macromolecular proteins of rapeseed meals were hydrolyzed by immobilized protease into small molecules such as polypeptides or amino acids. Thus, a novel efficient and economic way for the recycling of enzymes in the application of continuous production of active peptides was provided based on these magnetic nanoparticles.

Jin, Xin; Li, Ju-Fang; Huang, Ping-Ying; Dong, Xu-Yan; Guo, Lu-Lu; Yang, Liang; Cao, Yuan-Cheng; Wei, Fang; Zhao, Yuan-Di; Chen, Hong

2010-07-01

233

Mechanisms of hydrolysis of phenyl- and benzyl 4-nitrophenyl-sulfamate esters.  

PubMed

The kinetics of hydrolysis at medium acid strength (pH interval 2-5) of a series of phenylsulfamate esters 1 have been studied and they have been found to react by an associative S(N)2(S) mechanism with water acting as a nucleophile attacking at sulfur, cleaving the S-O bond with simultaneous formation of a new S-O bond to the oxygen of a water molecule leading to sulfamic acid and phenol as products. In neutral to moderate alkaline solution (pH ? ~ 6-9) a dissociative (E1cB) route is followed that involves i) ionization of the amino group followed by ii) unimolecular expulsion of the leaving group from the ionized ester to give N-sulfonylamine [HN=SO(2)] as an intermediate. In more alkaline solution further ionization of the conjugate base of the ester occurs to give a dianionic species which expels the aryloxide leaving group to yield the novel N-sulfonylamine anion [(-)N=SO(2)]; in a final step, rapid attack of hydroxide ion or a water molecule on it leads again to sulfamic acid. A series of substituted benzyl 4-nitrophenylsulfamate esters 4 were hydrolysed in the pH range 6.4-14, giving rise to a Hammett relationship whose reaction constant is shown to be consistent with the E1cB mechanism. PMID:20976313

Spillane, William J; Thea, Sergio; Cevasco, Giorgio; Hynes, Michael J; McCaw, Cheryl J A; Maguire, Neil P

2011-01-21

234

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

235

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

236

Alkaline Band Formation in Chara corallina  

PubMed Central

The nature of the transport system responsible for the establishment of alkaline bands on cells of Chara corallina was investigated. The transport process was found to be insensitive to external pH, provided the value was above a certain threshold. At this threshold (pH 5.1 to 4.8) the transport process was inactivated. Transport function could be recovered by raising the pH value of the external solution. The fastest rate of recovery was always obtained in the presence of exogenous HCO3?. Experiments in which plasmalemma integrity was modified using 10 millimolar K+ treatment were also performed. Alkaline band transport was significantly reduced in the presence of 10 millimolar K+, but the system did not recover, following return to 0.2 millimolar K+ solutions, until the transport site was reexposed to exogenous HCO3?. The influence of presence and absence of various cations on both alkaline band transport and total H14CO3? assimilation was examined. No specific cation requirement (mono- or divalent) was found for either process, except the previously established role of Ca2+ at the HCO3? transport site. The alkaline band transport process exhibited a general requirement for cations. This transport system could be partially or completely stalled in low cation solutions, or glass-distilled water, respectively. The results indicate that no cationic flux occurs across the plasmalemma in direct association with either the alkaline band or HCO3? transport systems. It is felt that the present results offer support for the hypothesis that an OH? efflux transport system (rather than a H+ influx system) is responsible for alkaline band development in C. corallina. The results support the hypothesis that OH? efflux is an electrogenic process. This OH? transport system also appears to contain two allosteric effector sites, involving an acidic group and a HCO3? ion.

Lucas, William J.

1979-01-01

237

Experimental survey of rechargeable alkaline zinc electrodes  

NASA Astrophysics Data System (ADS)

Rechargeable alkaline zinc-air cells and zinc-manganese dioxide cells need zinc electrodes working for at least 100 cycles under anode limiting conditions. The discharge of the manganese dioxide cathode especially must be limited to a definite fraction (1/3) of its available capacity to obtain a good cycle life. This study proposes a new test cell for investigations on pasted alkaline zinc powder electrodes. When, following experimentation, the value of the construction was established, a series of different electrode mixtures was cycled. It was found that 100 full discharges could be obtained with a zinc utilization of about 30 percent in the final cycles.

Binder, L.; Odar, W.

1984-09-01

238

Reactiveincompatibility of cumene hydroperoxide mixedwith alkaline solutions  

Microsoft Academic Search

Cumene hydroperoxide\\u000a (CHP) is classified as a flammable hazard in NFPA 43B. Fires or explosions\\u000a induced by thermal hazards ascribed to the unstable hydroperoxyl or peroxyl\\u000a groups are often reported. This sequence studies is aimed at the decomposition\\u000a phenomena associated with the reactive and incompatible characteristics of\\u000a CHP mixed with alkaline solutions. Various alkalines were used for comparing\\u000a the relative

H. Y. Hou; Y. S. Duh; W. H. Lin; C. M. Shu

2006-01-01

239

Alkaline earth filled nickel skutterudite antimonide thermoelectrics  

SciTech Connect

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

240

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

241

Degradation of halogenated carbons in alkaline alcohol  

NASA Astrophysics Data System (ADS)

1,1,2-Trichloro-trifluoroethane, 1,2-dibromo-tetrafluoroethane, 2,3,4,6-tetrachlorophenol, 1,2,4-trichlorobenzene, and 2,4,6-trichloroanisole were dissolved in alkaline isopropyl alcohol and irradiated with 60Co gamma rays after purged with pure nitrogen gas. The concentration of the hydroxide ions and the parent molecules decreased with the dose, while that of the halide ions and the organic products, with less halogen atoms than the parent, increased. Chain degradation will occur in alkaline isopropyl alcohol.

Nakagawa, Seiko; Shimokawa, Toshinari

2002-02-01

242

Effects of acid/alkaline pretreatment and gamma-ray irradiation on extracellular polymeric substances from sewage sludge  

NASA Astrophysics Data System (ADS)

In order to investigate the mechanism of extracellular polymeric substances (EPS) influencing sludge characteristics, variations of extractable EPS from municipal sewage sludge by acid/alkaline pretreatment and gamma-ray irradiation were studied. The changes in constituents of EPS were analyzed by UV-vis spectra and SEM images. The effects of alkaline pretreatment and gamma-ray irradiation on the functional groups in EPS were investigated by Fourier transform infrared (FTIR) spectrometer. Results showed that the extractable EPS increased clearly with increasing irradiation dose from 0 to 15 kGy. UV-vis spectra indicated that a new absorption band from 240 nm to 300 nm existed in all irradiated samples, apart from acid condition. The results of FTIR spectroscopic analysis indicated that, irradiation influenced major functional groups in EPS, such as protein and polysaccharide, and these effects were clearer under alkaline condition. SEM images provided that after alkaline hydrolysis, gamma-ray irradiation was more effective in resulting in the sludge flocs and cells broken, compared with acid pretreatment (pH 2.50).

Xie, Shuibo; Wu, Yuqi; Wang, Wentao; Wang, Jingsong; Luo, Zhiping; Li, Shiyou

2014-04-01

243

Recycling cellulases by pH-triggered adsorption-desorption during the enzymatic hydrolysis of lignocellulosic biomass.  

PubMed

Recycling of cellulases is an effective way to reduce the cost of enzymatic hydrolysis for the production of cellulosic ethanol. In this study, we examined the adsorption and desorption behaviors of cellulase at different pH values and temperatures. Furthermore, we developed a promising way to recover both free and bound cellulases by pH-triggered adsorption-desorption. The results show that acidic pH (e.g., pH 4.8) was found to favor adsorption, whereas alkaline pH (e.g., pH 10) and low temperature (4-37 °C) favored desorption. The adsorption of cellulases reached an equilibrium within 60 min at pH 4.8 and 25 °C, leading to approximately 50 % of the added cellulases bound to the substrate. By controlling the pH of eluent (citrate buffer, 25 °C), we were able to increase the desorption efficiency of bound cellulases from 15 % at pH 4.8 to 85 % at pH 10. To recover cellulases after enzymatic hydrolysis, we employed adsorption by fresh substrate and desorption at pH 10 to recover the free cellulases in supernatant and the bound cellulases in residue, respectively. The recycling performance (based on the glucose yield) of this simple strategy could reach near 80 %. Our results provided a simple, low-cost, and effective approach for cellulase recycling during the enzymatic hydrolysis of lignocellulosic biomass. PMID:24752845

Shang, Yaping; Su, Rongxin; Huang, Renliang; Yang, Yang; Qi, Wei; Li, Qiujin; He, Zhimin

2014-06-01

244

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

245

Hydrolysis of polyesters by serine proteases.  

PubMed

The substrate specificity of alpha-chymotrypsin and other serine proteases, trypsin, elastase, proteinase K and subtilisin, towards hydrolysis of various polyesters was examined using poly(L-lactide) (PLA), poly(beta-hydroxybutyrate) (PHB), poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBS/A), poly[oligo(tetramethylene succinate)-co-(tetramethylane carbonate)] (PBS/C), and poly(epsilon-caprolactone) (PCL). alpha-Chymotrypsin could degrade PLA and PEA with a lower activity on PBS/A. Proteinase K and subtilisin degraded almost all substrates other than PHB. Trypsin and elastase had similar substrate specificities to alpha-chymotrypsin. PMID:15928850

Lim, Hyun-A; Raku, Takao; Tokiwa, Yutaka

2005-04-01

246

nanoparticles fabricated by modified hydrolysis technique  

NASA Astrophysics Data System (ADS)

We have tested modified hydrolysis method for the preparation of ?-Fe2O3 nanoparticles. The particles after synthesis were applied for a series of physicochemical techniques. Iron chloride was used as a precursor material. The particle size distribution was determined using zeta sizer and scanning electron microscopy. The surface area and the morphology of the particles vary by changing the concentration of the precursor material. The size of nanoparticles varies from 10 to 90 nm. The particles having size of 23 ± 1 nm were separated out from the solution and their size remains almost the same even after one month. Energy dispersive X-ray analysis (EDX) of Fe2O3 nanoparticles confirms the purity of the desired material. The weight loss of the particles with respect to the temperature was studied by thermogravimetric and differential thermogravimetric (TG/DTG) analysis. X-ray diffraction (XRD) has been employed to study the crystallinity of the particles.

Waseem, Muhammad; Munsif, Sajida; Rashid, Umer; Imad-ud-Din

2014-06-01

247

Transport and hydrolysis of peptides by microorganisms.  

PubMed

The structural specificities of the dipeptide and oligopeptide permeases of E. coli are briefly reviewed and related to the requirements found for other microorganisms. New, quick, sensitive methods for studying peptide transport are described, based on the following: (i) peptide-dependent incorporation of free radioactive amino acid into newly synthesized protein by a double amino acid auxotroph, (ii) colorimetric assay of peptide-dependent enzyme synthesis by an amino acid auxotroph, (iii) dansyl fingerprint technique. These approaches provide information on peptide binding affinity to a permease and rates of peptide uptake and amino acid efflux. Among current and future research areas considered are: the influence of the pKb of the N-terminal amino group on transport, generality of peptide transport in microorganisms, energy coupling and regulation, involvement of binding proteins, and the 'smugglin' concept. Peptide hydrolysis, and nutritional ultilization of peptides, by microorganisms are briefly discussed. PMID:340177

Payne, J W

1977-01-01

248

Effect of sodium polyacrylate on the hydrolysis of octacalcium phosphate  

Microsoft Academic Search

Octacalcium phosphate (OCP) hydrolysis into hydroxyapatite (HA) has been investigated in aqueous solutions at different concentrations of sodium polyacrylate (NaPA). In the absence of the polyelectrolyte, OCP undergoes a complete transformation into HA in 48 h . The hydrolysis is inhibited by the polymer, which is significantly adsorbed on the crystals, up to about 22 wt.%. A polymer concentration of

Adriana Bigi; Elisa Boanini; Giuseppe Falini; Silvia Panzavolta; Norberto Roveri

2000-01-01

249

Hydrolysis of oligosaccharides by cation exchanger silica gels  

Microsoft Academic Search

Sulfonic acid cation-exchange resin usually synthesized from styrene divinylbenzene copolymers are not well effective as catalysts of oligosaccharides hydrolysis. The present paper deals with the rate of hydrolysis of oligosaccharides on a new cation exchanger obtained by grafting sulfonic groups on porous silica. With the large pore sizes, the sieving effect of large solutes is suppressed and the catalytic activity

Alain Heyraud; Marguerite Rinaudo

1982-01-01

250

Kinetic study of the acid hydrolysis of sugar cane bagasse  

Microsoft Academic Search

Economic interest in xylitol production can be enhanced if the needed xylose solutions can be obtained from the hydrolysis of low-cost lignocellulosic wastes. Sugar cane bagasse is a renewable, cheap and widely available waste in tropical countries. The hydrolysis of sugar cane bagasse to obtain xylose solutions has a double consequence, the elimination of a waste and the generation of

R Aguilar; J. A Ram??rez; G Garrote; M Vázquez

2002-01-01

251

Continuous acid hydrolysis of waste cellulose for ethanol production  

Microsoft Academic Search

The continuous dilute acid hydrolysis of waste cellulose materials (paper pulp and wood sawdust at 10 and 95% solids, respectively) to glucose in a twin screw reactor gave high conversion yields and good energy efficiencies. A scheme for a scaled-up acid hydrolysis-fermentation distillation facility based on a waste cellulose feedstock to produce fuel-grade ethanol is proposed.

B. Rugg; W. Brenner

1980-01-01

252

The laccase-catalyzed modification of lignin for enzymatic hydrolysis  

Microsoft Academic Search

The efficient use of cellulases in the hydrolysis of pretreated lignocellulosic biomass is limited due to the presence of lignin. Lignin is known to bind hydrolytic enzymes nonspecifically, thereby reducing their action on carbohydrate substrates. The composition and location of residual lignin therefore seem to be important for optimizing the enzymatic hydrolysis of lignocellulosic substrates. The use of lignin-modifying enzymes

Ulla Moilanen; Miriam Kellock; Sari Galkin; Liisa Viikari

253

Protein recovery from mechanically deboned turkey residue by enzymic hydrolysis  

Microsoft Academic Search

Enzymic hydrolysis was used to recover a potentially edible high protein hydrolysate from mechanically deboned turkey residue (MDTR), a turkey processing waste. The hydrolysis process reduced the weight of the original MDTR by 51% on a dry weight basis, and recovered 46% of the MDTR proteins. The hydrolysate contained 78% protein, 4·6% ash and only 5·7% fat. The proteins consisted

L. G. Fonkwe; R. K. Singh

1996-01-01

254

Transcript assisted phosphodiester bond hydrolysis by eukaryotic RNA polymerase II  

PubMed Central

Hydrolysis of the phosphodiester bonds of the transcript by bacterial RNA polymerase is assisted by 3?NMP of the RNA. Here we provide evidence that this mechanism is also involved in RNA cleavage by eukaryotic RNA polymerase II, suggesting that transcript assisted hydrolysis has emerged before divergence of bacteria and archaea/eukaryotes.

Nielsen, Soren; Zenkin, Nikolay

2013-01-01

255

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

256

Kinetic study of sphingomyelin hydrolysis for ceramide production  

Microsoft Academic Search

Kinetic study of sphingomyelin hydrolysis catalyzed by Clostridium perfringens phospholipase C was, at the first time, conducted for ceramide production. Ceramide has the major role in maintaining the water-retaining properties of the epidermis. Hence, it is of great commercial potential in cosmetic and pharmaceutical industries such as in hair and skin care products. The enzymatic hydrolysis of sphingomyelin has been

Long Zhang; Lars I. Hellgren; Xuebing Xu

2008-01-01

257

ENHANCING ENZYMATIC HYDROLYSIS OF RICE STRAW BY MICROWAVE PRETREATMENT  

Microsoft Academic Search

In an attempt to elucidate the effect of microwave pretreatment (MP) on enzymatic hydrolysis of rice straw (RS), three distinct MP procedures, microwave treatment (MT) alone, MT and alkali treatment (AT) together, and MT after AT, were investigated and compared with conventional alkali pretreatment (AP) by measurement of reducing sugar during its enzymatic hydrolysis. The combination of MT and AT

Zhu Shengdong; Yu Ziniu; Wu Yuanxin; Zhang Xia; Li Hui; Gao Ming

2005-01-01

258

Microwave-assisted hydrolysis of nitroglycerin (NG) under mild alkaline conditions: new insight into the degradation pathway.  

PubMed

Nitroglycerin (NG), a nitrate ester, is widely used in the pharmaceutical industry and as an explosive in dynamite and as propellant. Currently NG is considered as a key environmental contaminant due to the discharge of wastewater tainted with the chemical from the military and pharmaceutical industry. The present study describes hydrolytic degradation of NG (200 microM) at pH 9 using either conventional or microwave-assisted heating at 50 degrees C. We found that hydrolytic degradation of NG inside the microwave chamber was much higher than its degradation using conventional heating. Products distributions in both heating systems were closely related and included nitrite, nitrate, formic acid, and the novel intermediates 2-hydroxypropanedial (OCHCH(OH)HCO) and glycolic acid (CH2(OH)COOH). Two other intermediates glycolaldehyde (CH2(OH)CHO) and glyoxylic acid (CHOCOOH) were only detected in the microwave treated samples. The molar ratio of nitrite to nitrate in the presence and absence of microwave heating was 2.5 and 2.8, respectively. In both microwave assisted and conventional heating a nitrogen mass balance of 96% and 98% and a carbon mass balance of 58% and 78%, respectively, were obtained. The lower C mass recovery might be attributed to further unknown reactions, e.g., polymerization of the aldehydes CH2(OH)CHO, CHOCOOH and OCHCH(OH)HCO. A hydrolytic degradation pathway for NG was proposed involving denitration (loss of 2 NO2(-)) from the two primary carbons and the loss of one nitrate from the secondary carbon to produce 2-hydroxypropanedial. PMID:20129642

Halasz, Annamaria; Thiboutot, Sonia; Ampleman, Guy; Hawari, Jalal

2010-03-01

259

Glycerol production from glucose in alkaline medium  

Microsoft Academic Search

Glycerol production from glucose using an osmophilic yeast Pichia farinosa (ATCC 20210) in an alkaline medium has been investigated in shake flasks. The amount, form and mode of sodium carbonate addition have been found to affect the yields of glycerol, ethanol and biomass. These effects are explained in terms of the critical parameters of pH and dissolved oxygen levels in

P. Vijaikishore; N. G. Karanth

1984-01-01

260

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

261

An improved cathode for alkaline fuel cells  

Microsoft Academic Search

The use of nickel foam as an electrode substrate in alkaline fuel cells (AFCs) has been investigated for bipolar cells incorporating an electrically conducting gas diffusion layer (GDL). Improved performance, compared to a previous design, was obtained by adding an extra active layer (AL) composed of manganese (IV) oxide (MnO2) deposited onto carbon black. This new cathode design performed significantly

F. Bidault; D. J. L. Brett; P. H. Middleton; N. Abson; N. P. Brandon

2010-01-01

262

ISSUES WITH ALKALINE TREATMENT OF SLUDGE  

EPA Science Inventory

This presentation begins with a discussion of the use of lime and other alkaline materials from the very earliest times to the present for killing bacteria, viruses and parasites and for controlling odors in wastewaters and sludge. It answers the question "How did EPA arrive at i...

263

EFFICIENT PROTEOLYSIS AND APPLICATION OF AN ALKALINE PROTEASE FROM HALOPHILIC Bacillus sp. EMB9.  

PubMed

A salt-stable alkaline protease from moderately halophilic Bacillus sp. EMB9, isolated from the western coast of India, is described. This protease was capable of efficiently removing silver from used/waste X-Ray films, as well as hydrolyzing defatted soy flour with 31% degree of hydrolysis (DH). Production of the protease was optimized by using response surface methodology. Ca(2+) and NaCl were the most critical factors in enhancing the yield. Under optimized culture conditions, a maximum of 369 U protease/mL was obtained, which is quite comparable to the yields of commercial proteases. The elevated production level coupled with ability to efficiently hydrolyze protein-laden soy flour and complete recovery of silver from used X-Ray films makes it a prospective industrial enzyme. PMID:24905047

Sinha, Rajeshwari; Srivastava, A K; Khare, S K

2014-10-01

264

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

265

Xylans inhibit enzymatic hydrolysis of lignocellulosic materials by cellulases.  

PubMed

Hemicelluloses have been found to be physical barriers in the hydrolysis of cellulose, and prevent the access of enzymes to cellulose surface. In addition, soluble hemicelluloses may strongly inhibit the cellulase activity. In this work, birchwood xylan clearly inhibited the enzymatic hydrolysis of wheat straw, Avicel and nanocellulose by cellulases. Hydrolysis efficiencies of cellobiohydrolase I (CBHI, from Thermoascus aurantiacus), cellobiohydrolase II (CBHII, from Trichoderma reesei) and endoglucanase II (from T. aurantiacus) were clearly inhibited by birchwood xylan, respectively. The strongest inhibitory effect of birchwood xylan was observed on the hydrolysis of Avicel by CBHI and CBHII, as a dramatically decreased formation of the main product, cellobiose. After additions of soluble and insoluble oat spelt xylan, cleaved cellobiose units by CBHI from cellulose chain decreased from 8 to 4 and 6, respectively. The results in this work demonstrated that xylans clearly inhibited the hydrolysis efficiencies of both endoglucanase and cellobiohydrolase. PMID:22858461

Zhang, Junhua; Tang, Ming; Viikari, Liisa

2012-10-01

266

Improvement of thermal hydrolysis rate of dichloroacetic acid using alcohol.  

PubMed

Dichloroacetic acid (DCAA) is produced during the oxidation of trichloroethylene. It is also produced in drinking water treatment as a disinfection by-product. DCAA is a problem material, because of its toxicity. The objective of this research is to find the final products and the reaction pathway of the DCAA decomposition by hydrolysis, and to increase the hydrolysis rate. The removal of both chlorine atoms in DCAA structure was achieved with hydrolysis at around 75 degrees C, and the final products were oxalic acid and glycolic acid. The reaction pathway was the production of oxalic acid and glycolic acid from two glyoxylic acid molecules by Cannizzaro reaction after the glyoxylic acid production from dechlorination of DCAA with hydrolysis. The hydrolysis rate of DCAA was increased with the use of 90% ethanol solution as solvent. The activation energy of DCAA was about 80 kJ/mol in it, while it was around 105 kJ/mol in water. PMID:12892671

Okuda, Tetsuji; Nam, Se Yong; Lim, Jae Lim; Shin, Hang Sik

2003-10-01

267

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

268

Factors affecting cellulose hydrolysis based on inactivation of adsorbed enzymes.  

PubMed

The rate of enzymatic hydrolysis of cellulose reaction is known to decrease significantly as the reaction proceeds. Factors such as reaction temperature, time, and surface area of substrate that affect cellulose conversion were analyzed relative to their role in a mechanistic model based on first order inactivation of adsorbed cellulases. The activation energies for the hydrolytic step and inactivation step were very close in magnitude: 16.3kcalmol(-1) for hydrolysis and 18.0kcalmol(-1) for inactivation, respectively. Therefore, increasing reaction temperature would cause a significant increase in the inactivation rate in addition to the catalytic reaction rate. Vmax,app was only 20% or less of the value at 72h compared to at 2h as a result of inactivation of adsorbed cellulases, suggesting prolonged hydrolysis is not an efficient way to improve cellulose hydrolysis. Hydrolysis rate increased with corresponding increases in available substrate surface binding area. PMID:25027809

Ye, Zhuoliang; Berson, R Eric

2014-09-01

269

Sesame cake protein hydrolysis by alcalase: Effects of process parameters on hydrolysis, solubilisation, and enzyme inactivation  

Microsoft Academic Search

We investigated the effects of process parameters (substrate concentration, enzyme concentration, temperature and pH) on the\\u000a hydrolysis and solubilization of sesame cake protein as well as enzyme stability. The sesame cake protein was hydrolyzed by\\u000a Alcalase enzyme (a bacterial protease produced by a selected strain of Bacillus Licheniformis) that was chosen among five commercial enzymes examined. The optimum process conditions

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

2011-01-01

270

Titanium corrosion in alkaline hydrogen peroxide environments  

NASA Astrophysics Data System (ADS)

The corrosion of Grade 2 titanium in alkaline hydrogen peroxide environments has been studied by weight loss corrosion tests, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) measurements and potentiodynamic polarography. Calcium ions and wood pulp were investigated as corrosion inhibitors. In alkaline peroxide, the titanium corrosion rate increased with increasing pH, temperature, and hydrogen peroxide concentration. The corrosion controlling mechanism is thought to be the reaction of the oxide with the perhydroxyl ion. No evidence of thermodynamically stable calcium titanate was found in the surface film of test coupons exposed to calcium-inhibited alkaline peroxide solutions. Calcium inhibition is probably the result of low local alkali and peroxide concentrations at the metal surface produced by reaction of adsorbed calcium with hydrogen peroxide. It has been shown that the inhibiting effect of calcium is temporary, possibly through an effect of calcium on the chemical and/or physical stability of the surface oxide. Pulp is an effective and stable corrosion inhibitor. Raising the pulp concentration decreased the corrosion rate. The inhibiting effect of pulp may be related to the adsorption and interaction of the pulp fibers with H 2O2, thereby decreasing the peroxide concentration and rendering the solution less corrosive. The presence of both pulp and calcium led to higher corrosion rates than obtained by either one inhibitor alone. Replacement of hydrofluoric acid with alkaline peroxide for pickling of titanium was investigated. Titanium corrosion rates in alkaline peroxide exceeded those obtained in the conventional hydrofluoric acid bath. General corrosion was observed with extensive roughening of the surface giving a dull gray appearance. Preferred dissolution of certain crystallographic planes was investigated through the corrosion of a titanium single crystal. Whereas the overall effect on the corrosion rate was small, the plane close to a prismatic plane orientation appeared to be the most corrosion resistant plane. The plane close to a basal plane orientation suffered from extensive pitting and roughening of the surface.

Been, Jantje

271

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 ...

272

Human and Mouse Alkaline Ceramidase 1 and Skin Diseases.  

National Technical Information Service (NTIS)

Newly discovered, isolated, and cloned human alkaline ceramidase 1 (haCER1) and mouse alkaline ceramidase 1 (maCER1) are provided, which are predominantly expressed in skin cells and hydrolyze D-erthyro-ceramide exclusively.

C. Mao L. M. Obeid R. Xu

2005-01-01

273

Efficient rate enhancement due to intramolecular general base (IGB) assistance in the hydrolysis of N-(o-hydroxyphenyl)phthalimide.  

PubMed

The rates of the hydrolyses of N-(o-hydroxyphenyl)phthalimide (1) and N-(o-methoxyphenyl)phthalimide (2), studied at different pH, show that the hydrolysis of 1 involves intramolecular general base (IGB) assistance where the o-O- group of ionized 1 acts as IGB and H2O as the reactant. The rate enhancement due to the IGB-assisted reaction of H2O with ionized 1 is>8x10(4)-fold. Pseudo-first-order rate constant for the reaction of water with 2 is approximately 2x10(3)-fold smaller than the first-order rate constant (0.10 s-1) for pH-independent hydrolysis of 1 within the pH range of 9.60-10.10. Second-order rate constants (kOH) for hydroxide ion-assisted hydrolysis of ionized 1 and 2 are 3.0 and 29.1 M-1 s-1, respectively. The solvent deuterium kinetic isotope effect (dKIE) on the rate of alkaline hydrolysis of 1 and 2 reveals that the respective values of kOH/kOD are 0.84 and 0.78, where kOD represents the second-order rate constant for DO--assisted cleavage of these imides (1 and 2). The value of kwH2O/kdD2O is 2.04, with kwH2O and kdD2O representing pseudo-first-order rate constants for the reactions of ionized 1 with H2O and D2O, respectively. PMID:17341117

Sim, Yoke-Leng; Ariffin, Azhar; Khan, M Niyaz

2007-03-30

274

Nonenzymatic glycosylation of alkaline phosphatase alters its biological  

Microsoft Academic Search

Hyperglycaemia in poorly controlled diabetic patients induces non-enzymatic glycosylation (glycation) of proteins, altering their structure and physiological bioactivity. Alkaline phosphatase (ALP) is a membrane-bound exoenzyme which faces the extracellular compartment. We have investigated the glycation of intestinal alkaline phosphatase in vitro and the consequences of such molecular modifications on certain structural and functional characteristics. The effect of glycation on alkaline

Antonio D. McCarthy; Ana M. Cortizo; Griselda Giménez Segura; Liliana C. Bruzzone; Susana B. Etcheverry

1998-01-01

275

Enzymatic and alkaline treatments of hardwood dissolving pulp  

Microsoft Academic Search

Dissolving pulp was solubilized in 9% NaOH, resulting in 32% solubilization of the pulp. Most of the pulp hemicelluloses were solubilized during this treatment. During the alkaline treatment the cellulose crystalline form was converted from cellulose I to cellulose II. The alkaline insoluble residue was further treated with cellulases in order to render it more alkaline soluble (two-step process). The

L. RAHKAMO; L. VIIKARI; J. BUCHERT; T. PAAKKARI; T. SUORTTI

1998-01-01

276

FINAL REPORT. ACTINIDE-ALUMINATE SPECIATION IN ALKALINE RADIOACTIVE WASTE  

EPA Science Inventory

Investigation of behavior of actinides in alkaline media containing Al(III) showed that no aluminate complexes of actinides in oxidation states (III-VII) were formed in alkaline solutions. At alkaline precipitation (pH 10-14) of actinides in presence of Al(III) formation of alumi...

277

Factors impeding enzymatic wheat gluten hydrolysis at high solid concentrations.  

PubMed

Enzymatic wheat gluten hydrolysis at high solid concentrations is advantageous from an environmental and economic point of view. However, increased wheat gluten concentrations result in a concentration effect with a decreased hydrolysis rate at constant enzyme-to-substrate ratios and a decreased maximum attainable degree of hydrolysis (DH%). We here identified the underlying factors causing the concentration effect. Wheat gluten was hydrolyzed at solid concentrations from 4.4% to 70%. The decreased hydrolysis rate was present at all solid concentrations and at any time of the reaction. Mass transfer limitations, enzyme inhibition and water activity were shown to not cause this hydrolysis rate limitation up to 50% solids. However, the hydrolysis rate limitation can be, at least partly, explained by a second-order enzyme inactivation process. Furthermore, mass transfer impeded the hydrolysis above 60% solids. Addition of enzyme after 24?h at high solid concentrations scarcely increased the DH%, suggesting that the maximum attainable DH% decreases at high solid concentrations. Reduced enzyme activities caused by low water activities can explain this DH% limitation. Finally, a possible influence of the plastein reaction on the DH% limitation is discussed. Biotechnol. Bioeng. 2014;111: 1304-1312. © 2014 Wiley Periodicals, Inc. PMID:24474643

Hardt, N A; Janssen, A E M; Boom, R M; van der Goot, A J

2014-07-01

278

Determination of the individual rate and association constants of the hydrolysis catalysed by serine proteinases by means of added nucleophiles in Eisenthal and Cornish-Bowden coordinates.  

PubMed

It is shown that in the three-step enzyme-catalysed hydrolysis the addition of nucleophile shifts the common intersection point in Eisenthal and Cornish-Bowden coordinates when registering the second product P2. The different points obtained at different nucleophile concentrations are situated on a straight line with intercepts Ks on the Km axis and k3 [E]o on the V axis. Since the Eisenthal and Cornish-Bowden method is considered as the best graphic method for determination of the kinetic parameters Km and V of enzyme reactions, the graphic procedure proposed here for determination of k2, k3, k4 and Ks by the method of added nucleophile to be preferred. This procedure was applied for determination of individual constants on the hydrolysis of N-acetylated L-amino acid methyl esters catalysed by alkaline mesentericopeptidase. PMID:6998498

Dorovska-Taran, V; Raykova, D

1980-10-01

279

Photolysis of alkaline-earth nitrates  

NASA Astrophysics Data System (ADS)

Peroxynitrite and nitrite ions are the diamagnetic products of photolysis (with light at a wavelength of 253.7 nm) of alkaline-earth nitrates; the paramagnetic products and hydrogen peroxide were not found. The structural water in alkaline-earth nitrate crystals did not affect the qualitative composition of the photodecomposition products. The quantum yield of nitrite ions was 0.0012, 0.0038, 0.0078, and 0.0091 quanta-1 and that of peroxynitrite ions was 0.0070, 0.0107, 0.0286, and 0.0407 quanta-1 for Sr(NO3)2, Ba(NO3)2, Ca(NO3)2 · 4H2O, and Mg(NO3)2 · 6H2O, respectively.

Kriger, L. D.; Miklin, M. B.; Dyagileva, E. P.; Anan'ev, V. A.

2013-02-01

280

A conceptual model of mildly alkaline water discharging from the Zlatibor ultramafic massif, western Serbia  

NASA Astrophysics Data System (ADS)

Ultramafic rocks are generally taken to be `waterless' or bearing little water. The mountain Zlatibor, western Serbia, largely built of Upper Jurassic ultramafics, is without perennial springs. However, in Gruda, an area on the NE side of Zlatibor, there are two perennial ascending springs with uniform discharge: Bijela ?esma and Hajdu?ko Vrelo. The water from both springs is naturally mildly alkaline (pH ˜8.4), of Mg-HCO3 type, and temperature ˜11 °C. The springs have been investigated with respect to derivation, dynamics and chemistry with a view to commercial use of the water. The results indicate zones of rocks fractured during tectonic events and/or under lithostatic pressure. Deep ultramafic rocks, equivalent to abyssal peridotites (the least depleted rocks of the upper mantle, rich in magnesium), include fractured aquifers characterized by heterogeneity and anisotropy. Groundwater arriving at the land surface derives from atmospheric precipitation, and its quality is converted through the process of serpentine acid hydrolysis into mildly alkaline Mg-HCO3 water. Both quantity and quality of water from these springs are stable and are unaffected by atmospheric precipitation or other external influences. A conceptual model of the structure, hydrogeological character of the aquifer, and the mechanism of groundwater derivation is developed for both springs.

Niki?, Zoran; Sre?kovi?-Bato?anin, Danica; Burazer, Milenko; Risti?, Ratko; Papi?, Petar; Nikoli?, Vesna

2013-08-01

281

A Comparison between Lime and Alkaline Hydrogen Peroxide Pretreatments of Sugarcane Bagasse for Ethanol Production  

NASA Astrophysics Data System (ADS)

Pretreatment procedures of sugarcane bagasse with lime (calcium hydroxide) or alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 2 × 2 × 2 factorial designs, with pretreatment time, temperature, and lime loading and hydrogen peroxide concentration as factors. The responses evaluated were the yield of total reducing sugars (TRS) and glucose released from pretreated bagasse after enzymatic hydrolysis. Experiments were performed using the bagasse as it comes from an alcohol/ sugar factory and bagasse in the size range of 0.248 to 1.397 mm (12-60 mesh). The results show that when hexoses and pentoses are of interest, lime should be the pretreatment agent chosen, as high TRS yields are obtained for nonscreened bagasse using 0.40 g lime/g dry biomass at 70 °C for 36 h. When the product of interest is glucose, the best results were obtained with lime pretreatment of screened bagasse. However, the results for alkaline peroxide and lime pretreatments of nonscreened bagasse are not very different.

Rabelo, Sarita C.; Filho, Rubens Maciel; Costa, Aline C.

282

A comparison between lime and alkaline hydrogen peroxide pretreatments of sugarcane bagasse for ethanol production.  

PubMed

Pretreatment procedures of sugarcane bagasse with lime (calcium hydroxide) or alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 2(3) factorial designs, with pretreatment time, temperature, and lime loading and hydrogen peroxide concentration as factors. The responses evaluated were the yield of total reducing sugars (TRS) and glucose released from pretreated bagasse after enzymatic hydrolysis. Experiments were performed using the bagasse, as it comes from an alcohol/sugar factory and bagasse, in the size, range from 0.248 to 1.397 mm (12-60 mesh). The results show that, when hexoses and pentoses are of interest, lime should be the pretreatment agent chosen, as high TRS yields are obtained for non-screened bagasse using 0.40 g lime/g dry biomass at 70 degrees C for 36 h. When the product of interest is glucose, the best results were obtained with lime pretreatment of screened bagasse. However, the results for alkaline peroxide and lime pretreatments of non-screened bagasse are not very different. PMID:18404254

Rabelo, Sarita C; Filho, Rubens Maciel; Costa, Aline C

2008-01-01

283

A comparison between lime and alkaline hydrogen peroxide pretreatments of sugarcane bagasse for ethanol production.  

PubMed

Pretreatment procedures of sugarcane bagasse with lime (calcium hydroxide) or alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 2 x 2 x 2 factorial designs, with pretreatment time, temperature, and lime loading and hydrogen peroxide concentration as factors. The responses evaluated were the yield of total reducing sugars (TRS) and glucose released from pretreated bagasse after enzymatic hydrolysis. Experiments were performed using the bagasse as it comes from an alcohol/sugar factory and bagasse in the size range of 0.248 to 1.397 mm (12-60 mesh). The results show that when hexoses and pentoses are of interest, lime should be the pretreatment agent chosen, as high TRS yields are obtained for nonscreened bagasse using 0.40 g lime/g dry biomass at 70 degrees C for 36 h. When the product of interest is glucose, the best results were obtained with lime pretreatment of screened bagasse. However, the results for alkaline peroxide and lime pretreatments of nonscreened bagasse are not very different. PMID:18767207

Rabelo, Sarita C; Maciel Filho, Rubens; Costa, Aline C

2008-03-01

284

Microbial hydrolysis of organic nitriles and amides.  

PubMed

Nitrile-hydrating enzymes produced by bacteria and fungi catalyse the conversion of a large number of chemically diverse nitriles, including many economically important compounds used industrially for chemical synthesis of amides and acids. This paper presents data on two new, highly different nitrile-hydrolysing enzymes which were isolated in connection with our studies on enzymic nitrile transformations. Particular attention was paid to the enzymes' substrate specificities and sensitivity to substrate/product inhibition. One of our microbial isolates was a Rhodococcus sp. (strain CH5). This strain produces a constitutive hydratase that has a broad substrate spectrum, including aliphatic and aromatic nitriles, mononitriles and dinitriles, hydroxynitriles and amino-nitriles. It also produces a constitutive amidase of equally low substrate specificity. The hydratase/amidase system catalysed the hydrolysis of D,L-aminonitriles into racemic mixtures of amino acids. Strain CH5 is able to produce high concentrations of malonic acid monoamide from malononitrile and malonamide. The other isolate, Alcaligenes sp. (strain I4), can convert high concentrations of cyanoacetate into malonic acid, presumably by means of an aliphatic nitrilase that is specific for cyanoacetate. Enzyme kinetic experiments have shown that this enzyme is very resistant to both substrate and product inhibition. PMID:3073055

Ingvorsen, K; Yde, B; Godtfredsen, S E; Tsuchiya, R T

1988-01-01

285

Synthesis, hydrolysis and stability of psilocin glucuronide.  

PubMed

A two-step synthesis of psilocin glucuronide (PCG), the main metabolite of psilocin, with methyl 2,3,4-tri-O-isobutyryl-1-O-trichloroacetimidoyl-?-d-glucopyranuronate is reported. With the synthesized PCG, hydrolysis conditions in serum and urine were optimized. Escherichia coli proved to be a better enzyme source for ?-glucuronidase than Helix pomatia. It was essential to add ascorbic acid to serum samples to protect psilocin during incubation. Furthermore the stability of PCG and psilocin was compared as stability data are the basis for forensic interpretation of measurements. PCG showed a greater long-term stability after six months in deep frozen serum and urine samples than psilocin. The short-term stability of PCG for one week in whole blood at room temperature and in deep frozen samples was also better than that of psilocin. Therefore, PCG can be considered to be more stable than the labile psilocin and should always be included if psilocin is analyzed in samples. PMID:24513688

Martin, Rafaela; Schürenkamp, Jennifer; Pfeiffer, Heidi; Lehr, Matthias; Köhler, Helga

2014-04-01

286

Review of alkaline fuel cell performance  

Microsoft Academic Search

The current technological status of alkaline fuel cells (AFC) was reviewed, focusing on small (0.5-5kWe) stationary units suitable for domestic CHP. Performance figures were found that represent the real-world capabilities of the state of the art technology. Both commercial and research systems were considered, so long as they could be suitable for a consumer product. Information was sourced from open

I. Staffell

287

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

288

Rechargeable alkaline zinc\\/ferricyanide battery  

Microsoft Academic Search

Technical and economic feasibility of the alkaline zinc\\/ferricy anide rechargeable battery for utility load leveling applications was assessed. This battery meets the requirements for this application with cell voltages of 1.94 V on charge and 1.78 V on discharge. Mean energy efficiency is 84% at 760 and 86% at 1110 4 hour cycles in full cell and redox half cell

G. B. Adams; R. P. Hollandsworth; B. D. Webber

1979-01-01

289

Alkaline black liquor treatment by continuous electrodialysis  

Microsoft Academic Search

Summary Investigations were carried out to study the feasibility of electrodialytic regeneration of alkaline black liquor in a continuously operated three-compartment electrodialyzer. Effects of current den- sity (5-25 mA\\/cm'), flow velocities of black liquor (o-20.9 cm\\/min) and distilled water (9.9-39.9 cm\\/min) , and percent soda recovery with various membrane arrangements were studied. A cation exchange-neutral membrane arrangement gave better percent

A. K. Mishra; P. K. Bhattacharya

1987-01-01

290

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

291

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

292

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.

2013-01-01

293

Electrospinning of an Alkaline Polymer Electrolyte  

NASA Astrophysics Data System (ADS)

The polymer electrolyte membrane is a key component of the low temperature fuel cell to block fuel and electron crossover, while enabling ions to pass and complete the half-cell reactions. Proton exchange membranes (PEMs) are anion-containing polymers, such as Nafion, which offer proton conduction pathways. Alkaline polymer electrolytes utilize hydroxyl anions as charge carriers and are currently being researched as an alternative to PEMs because they may offer the use of inexpensive metal catalysts. However, hydroxyl anion in an alkaline electrolyte has relatively low mobility compared to that of protons in an acid electrolyte; hence a high concentration of OH^- is required to obtain high ionic conductivity. Here, we report the use of an electrospinning process to prepare nonwoven membranes. Polysulfones are first functionalized with varied ionic content of quaternary ammonium functional groups and then are electrospun to get alkaline electrolyte mat. The morphology at various ionic content, mechanical property, and in-plane conductivity of resulting films will be discussed and compared to solvent-cast films of the same material.

Roddecha, Supacharee; Dong, Zexuan; Wu, Yiquan; Anthamatten, Mitchell

2010-03-01

294

Characterization of a Baculovirus Alkaline Nuclease†  

PubMed Central

All baculovirus genomes sequenced to date encode a homolog of an alkaline nuclease that has been characterized in the Herpesviridae. In this report we describe the characterization of the alkaline nuclease (AN) homolog of the Autographa californica multinucleocapsid nucleopolyhedrovirus (AcMNPV) (open reading frame 133). His-tagged AN constructs were expressed in recombinant baculoviruses and affinity purified, and then their enzymatic activity was characterized. AN was found to degrade linear DNA at alkaline pH, preferred Mg2+ over Mn2+, had optimal activity at 35°C, and did not appear to have a salt requirement. To rule out contamination by the endogenous baculovirus gene product or a cellular enzyme, point mutations were introduced into a highly conserved domain of the gene. These mutations were found to markedly reduce or eliminate most of the activity of the affinity-purified enzyme. An antibody generated against the protein was used to analyze its expression by Western blot analysis. AN was found to be expressed at low levels by 12 h postinfection, with maximal expression at 24 h postinfection. Attempts to generate a virus with this gene inactivated were unsuccessful, suggesting that AN may be encoded by an essential gene.

Li, Lulin; Rohrmann, George F.

2000-01-01

295

Improved alkaline stabilization of municipal wastewater sludge.  

PubMed

In Mexico, physicochemical sludge contains high levels of pathogens; and alkaline stabilization is an alternative for their control. However, the odours caused mainly by ammonia generation represent a disadvantage. On the other hand, the ammonia is known as an effective disinfectant. The aim of this study was to evaluate the disinfectant properties of ammonia in sludge, and use it in a closed alkaline stabilization system, which, not only copes with odours but also increases the efficiency of the process. Raw sludge from a municipal wastewater treatment plant using a physicochemical process was used. Ammonia was applied in doses from 10 to 50% w/w; also, doses from 5 to 40% of CaO were applied in open and closed systems and raw and treated sludge quality was evaluated. Results showed that ammonia removed 6 and 5 logs of faecal coliforms and Salmonella spp., respectively and up to 94% of viable helminth ova. The closed system was more efficient than the open system when applying doses from 5 to 20% of CaO. Finally, the results indicate that the ammonia represents an alternative to disinfecting wastewater sludge and it can be used to enhance alkaline stabilization processes. PMID:12479463

Méndez, J M; Jiménez, B E; Barrios, J A

2002-01-01

296

Characterization of a baculovirus alkaline nuclease.  

PubMed

All baculovirus genomes sequenced to date encode a homolog of an alkaline nuclease that has been characterized in the Herpesviridae. In this report we describe the characterization of the alkaline nuclease (AN) homolog of the Autographa californica multinucleocapsid nucleopolyhedrovirus (AcMNPV) (open reading frame 133). His-tagged AN constructs were expressed in recombinant baculoviruses and affinity purified, and then their enzymatic activity was characterized. AN was found to degrade linear DNA at alkaline pH, preferred Mg(2+) over Mn(2+), had optimal activity at 35 degrees C, and did not appear to have a salt requirement. To rule out contamination by the endogenous baculovirus gene product or a cellular enzyme, point mutations were introduced into a highly conserved domain of the gene. These mutations were found to markedly reduce or eliminate most of the activity of the affinity-purified enzyme. An antibody generated against the protein was used to analyze its expression by Western blot analysis. AN was found to be expressed at low levels by 12 h postinfection, with maximal expression at 24 h postinfection. Attempts to generate a virus with this gene inactivated were unsuccessful, suggesting that AN may be encoded by an essential gene. PMID:10864651

Li, L; Rohrmann, G F

2000-07-01

297

Arginine Coordination in Enzymatic Phosphoryl Transfer: Evaluation of the Effect of Arg166 Mutations in Escherichia Coli Alkaline Phosphatase  

SciTech Connect

Arginine residues are commonly found in the active sites of enzymes catalyzing phosphoryl transfer reactions. Numerous site-directed mutagenesis experiments establish the importance of these residues for efficient catalysis, but their role in catalysis is not clear. To examine the role of arginine residues in the phosphoryl transfer reaction, we have measured the consequences of mutations to arginine 166 in Escherichia coli alkaline phosphatase on hydrolysis of ethyl phosphate, on individual reaction steps in the hydrolysis of the covalent enzyme-phosphoryl intermediate, and on thio substitution effects. The results show that the role of the arginine side chain extends beyond its positive charge, as the Arg166Lys mutant is as compromised in activity as Arg166Ser. Through measurement of individual reaction steps, we construct a free energy profile for the hydrolysis of the enzyme-phosphate intermediate. This analysis indicates that the arginine side chain strengthens binding by {approx}3 kcal/mol and provides an additional 1-2 kcal/mol stabilization of the chemical transition state. A 2.1 {angstrom} X-ray diffraction structure of Arg166Ser AP is presented, which shows little difference in enzyme structure compared to the wild-type enzyme but shows a significant reorientation of the bound phosphate. Altogether, these results support a model in which the arginine contributes to catalysis through binding interactions and through additional transition state stabilization that may arise from complementarity of the guanidinum group to the geometry of the trigonal bipyramidal transition state.

O'Brien, P.J.; Lassila, J.K.; Fenn, T.D.; Zalatan, J.G.; Herschlag, D.

2009-05-22

298

The fate of added alkalinity in model scenarios of ocean alkalinization  

NASA Astrophysics Data System (ADS)

The deliberate large-scale manipulation of the Earth's climate (geo-engineering) has been proposed to mitigate climate change and ocean acidification. Whilst the mitigation potential of these technologies could sound promising, they may also pose many environmental risks. Our research aims at exploring the ocean-based carbon dioxide removal method of alkalinity enhancement. Its mitigation potential to reduce atmospheric CO2 and counteract the consequences of ocean acidification, risks and unintended consequences are studied. In order to tackle these questions, different scenarios are implemented in the state-of-the-art Earth system model of the Max Planck Institute for Meteorology. The model configuration is based on the 5th phase of the coupled model intercomparison project following a high CO2 future climate change scenario RCP8.5 (in which radiative forcing rises to 8.5 W/m² in 2100). Two different scenarios are performed where the alkalinity is artificially added globally uniformly in the upper ocean. In the first scenario, alkalinity is increased as a pulse by doubling natural values of the first 12 meters. In the second scenario we add alkalinity into the same ocean layer such that the atmospheric CO2 concentration is reduced from RCP8.5 to RCP4.5 levels (with the radiative forcing of 4.5 W/m² in 2100). We investigate the fate of the added alkalinity in these two scenarios and compare the differences in alkalinity budgets. In order to increase oceanic CO2 uptake from the atmosphere, enhanced alkalinity has to stay in the upper ocean. Once the alkalinity is added, it will become part of the biogeochemical cycles and it will be distributed with the ocean currents. Therefore, we are particularly interested in the residence time of the added alkalinity at the surface. Variations in CO2 partial pressure, seawater pH and saturation state of carbonate minerals produced in the implemented scenarios will be presented. Collateral changes in ocean biogeochemistry and climate will be also discussed.

Ferrer González, Miriam; Ilyina, Tatiana

2014-05-01

299

Intestinal alkaline phosphatase regulates protective surface microclimate pH in rat duodenum  

PubMed Central

Regulation of localized extracellular pH (pHo) maintains normal organ function. An alkaline microclimate overlying the duodenal enterocyte brush border protects the mucosa from luminal acid. We hypothesized that intestinal alkaline phosphatase (IAP) regulates pHo due to pH-sensitive ATP hydrolysis as part of an ecto-purinergic pH regulatory system, comprised of cell-surface P2Y receptors and ATP-stimulated duodenal bicarbonate secretion (DBS). To test this hypothesis, we measured DBS in a perfused rat duodenal loop, examining the effect of the competitive alkaline phosphatase inhibitor glycerol phosphate (GP), the ecto-nucleoside triphosphate diphosphohydrolase inhibitor ARL67156, and exogenous nucleotides or P2 receptor agonists on DBS. Furthermore, we measured perfusate ATP concentration with a luciferin–luciferase bioassay. IAP inhibition increased DBS and luminal ATP output. Increased luminal ATP output was partially CFTR dependent, but was not due to cellular injury. Immunofluorescence localized the P2Y1 receptor to the brush border membrane of duodenal villi. The P2Y1 agonist 2-methylthio-ADP increased DBS, whereas the P2Y1 antagonist MRS2179 reduced ATP- or GP-induced DBS. Acid perfusion augmented DBS and ATP release, further enhanced by the IAP inhibitor l-cysteine, and reduced by the exogenous ATPase apyrase. Furthermore, MRS2179 or the highly selective P2Y1 antagonist MRS2500 co-perfused with acid induced epithelial injury, suggesting that IAP/ATP/P2Y signalling protects the mucosa from acid injury. Increased DBS augments IAP activity presumably by raising pHo, increasing the rate of ATP degradation, decreasing ATP-mediated DBS, forming a negative feedback loop. The duodenal epithelial brush border IAP–P2Y–HCO3? surface microclimate pH regulatory system effectively protects the mucosa from acid injury.

Mizumori, Misa; Ham, Maggie; Guth, Paul H; Engel, Eli; Kaunitz, Jonathan D; Akiba, Yasutada

2009-01-01

300

Helium Isotopic Signatures of Icelandic Alkaline Lavas  

NASA Astrophysics Data System (ADS)

Iceland is widely accepted to be underlain by a plume of actively upwelling mantle. The nature of the individual mantle components within the plume however remains enigmatic. The most compelling evidence for involvement of relatively undegassed, `undepleted' mantle material are the high 3He/4He lavas (>20 RRa) that mainly extrude in the neovolcanic rift zone above the plume stem. It has been proposed that the high 3He4He mantle component is equivalent to the FOZO component on the basis of the Sr, Nd and Pb-isotopic signature of the most extreme high 3He4He sample (Selardalur, 37 RRa). The mildly alkaline centre Snaefell, which is situated close to the plume axis in SE Iceland, has Sr, Nd and Pb-isotopic ratios similar to the high 3He4He sample from Selardalur, which may indicate that Snaefell is mainly sourced by FOZO. Incompatible trace element-rich, high 87Sr/86Sr, 206Pb204Pb and low 143Nd144Nd alkaline basalts from the other off-rift zones have also been attributed to an `undepleted' plume component, which could be FOZO. However, 3He4He measurements of these alkaline lavas are sparse and are typically comparable to MORB values (Snaefellsnes & Vestmannaeyjar, 6.9-15.1 RRa, MORB, 9.13 {+/-}3.57 RRa). Furthermore, these centres have Sr, Nd and Pb- isotopic ratios, which are different from FOZO and have incompatible trace element patterns that are consistent with a high share of recycled oceanic basalt in their source. This study compares the Sr, Nd, Pb, He-isotope ratios and trace element characteristics of MgO-rich alkaline lavas from Eyjafjöll, Vestmannaeyjar, Snaefellsnes, Snaefell and Selardalur (NW Iceland) in order to assess whether the alkaline centres originate from different sources or variable mixtures thereof. Specifically, Snaefell and Selardalur are inspected in order to test whether the 3He/4He ratios and trace element characteristics are consistent with an origin from FOZO.

Breddam, K.; Kurz, M. D.

2001-12-01

301

Alkaline solution/binder ratio as a determining factor in the alkaline activation of aluminosilicates  

SciTech Connect

This study investigates the effect of the alkaline solution/binder (S/B) ratio on the composition and nanostructure of the reaction products generated in the alkaline activation of aluminosilicates. The experiments used two mixtures of fly ash and dehydroxylated white clay and for each of these, varying proportions of the solution components. The alkali activator was an 8 M NaOH solution (with and without sodium silicate) used at three S/B ratios: 0.50, 0.75 and 1.25. The {sup 29}Si, {sup 27}Al MAS NMR and XRD characterisation of the reaction products reveal that for ratios nearest the value delivering suitable paste workability, the reaction-product composition and structure depend primarily on the nature and composition of the starting materials and the alkaline activator used. However, when an excess alkaline activator is present in the system, the reaction products tend to exhibit SiO{sub 2}/Al{sub 2}O{sub 3} ratios of approximately 1, irrespective of the composition of the starting binder or the alkaline activator.

Ruiz-Santaquiteria, C., E-mail: ruiz.cs@ietcc.csic.es [Eduardo Torroja Institute (CSIC), c/Serrano Galvache, n Degree-Sign 4, 28033 Madrid (Spain); Skibsted, J. [Instrument Centre for Solid-State NMR Spectroscopy, Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark)] [Instrument Centre for Solid-State NMR Spectroscopy, Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Fernandez-Jimenez, A.; Palomo, A. [Eduardo Torroja Institute (CSIC), c/Serrano Galvache, n Degree-Sign 4, 28033 Madrid (Spain)] [Eduardo Torroja Institute (CSIC), c/Serrano Galvache, n Degree-Sign 4, 28033 Madrid (Spain)

2012-09-15

302

Hydrolysis of the amorphous cellulose in cotton-based paper.  

PubMed

Hydrolysis of cellulose in Whatman no. 42 cotton-based paper was studied using gel permeation chromatography (GPC), electrospray ionization-mass spectrometry (ESI-MS), and uniaxial tensile testing to understand the course and kinetics of the reaction. GPC results suggested that scission reactions passed through three stages. Additionally, the evolution of soluble oligomers in the ESI-MS data and the steady course of strength loss showed that the hydrolysis reaction occurred at a constant rate. These findings are explained with a more detailed description of the cellulose hydrolysis, which includes multiple chain scissions on amorphous segments. The breaks occur with increasing frequency near the ends of amorphous segments, where chains protrude from crystalline domains. Oligomers unattached to crystalline domains are eventually created. Late-stage reactions near the ends of amorphous segments produce a kinetic behavior that falsely suggests that hydrolysis had ceased. Monte Carlo simulations of cellulose degradation corroborated the experimental findings. PMID:18324778

Stephens, Catherine H; Whitmore, Paul M; Morris, Hannah R; Bier, Mark E

2008-04-01

303

Hydrolysis of whey lactose using CTAB-permeabilized yeast cells.  

PubMed

Disposal of lactose in whey and whey permeates is one of the most significant problems with regard to economics and environmental impact faced by the dairy industries. The enzymatic hydrolysis of whey lactose to glucose and galactose by beta-galactosidase constitutes the basis of the most biotechnological processes currently developed to exploit the sugar content of whey. Keeping this in view, lactose hydrolysis in whey was performed using CTAB permeabilized Kluyveromyces marxianus cells. Permeabilization of K. marxianus cells in relation to beta-galactosidase activity was carried out using cetyltrimethyl ammonium bromide (CTAB) to avoid the problem of enzyme extraction. Different process parameters (biomass load, pH, temperature, and incubation time) were optimized to enhance the lactose hydrolysis in whey. Maximum hydrolysis (90.5%) of whey lactose was observed with 200 mg DW yeast biomass after 90 min of incubation period at optimum pH of 6.5 and temperature of 40 degrees C. PMID:18431601

Kaur, Gurpreet; Panesar, Parmjit S; Bera, Manav B; Kumar, Harish

2009-01-01

304

Hydrolysis of Al3+ from constrained molecular dynamics  

NASA Astrophysics Data System (ADS)

We investigated the hydrolysis reactions of Al3+ in AlCl3 aqueous solution using the constrained molecular dynamics based on the Car-Parrinello molecular-dynamics method. By employing the proton-aluminum coordination number as a reaction coordinate in the constrained molecular dynamics the deprotonation as well as dehydration processes are successfully realized. From our free-energy difference of ?G0~=8.0 kcal mol-1 the hydrolysis constant pKa1 is roughly estimated as 5.8, comparable to the literature value of 5.07. We show that the free-energy difference for the hydrolysis of Al3+ in acidic conditions is at least 4 kcal mol-1 higher than that in neutral condition, indicating that the hydrolysis reaction is inhibited by the presence of excess protons located around the hydrated ion, in agreement with the change of the predominant species by pH.

Ikeda, Takashi; Hirata, Masaru; Kimura, Takaumi

2006-02-01

305

Hydrolysis of Cellulose by Purified Cellulase Components: Synergistic Effects.  

National Technical Information Service (NTIS)

The hydrolysis of cellulose by purified cellulase components is reported. The adsorption of purified cellobiohydrolases (CBH I and II) and endoglucanases (EG I and II) from Trichoderma reesei strain L27 to microcrystalline cellulose (Avicel) has been stud...

J. Woodward N. E. Lee

1987-01-01

306

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

307

Sucrose Hydrolysis-Temperature Dependence of the Activation Energy.  

National Technical Information Service (NTIS)

Sucrose hydrolysis is often cited as one of the classic examples of a chemical reaction with a temperature-dependent aactivation enery. Two different investigators, Moelwyn-Hughes (polarimetry) and Leininger and Kilpatrick (dilatometry), both claimed that...

J. R. Ward

1985-01-01

308

?-Tricalcium phosphate hydrolysis to octacalcium phosphate: effect of sodium polyacrylate  

Microsoft Academic Search

?-Tricalcium phosphate (?-TCP) hydrolysis into octacalcium phosphate (OCP) has been investigated in phosphoric acid solution at different concentrations of sodium polyacrylate (NaPA). The hydrolysis process has been followed by powder X-ray diffraction, infrared absorption and scanning electron microscopy analyses. In the absence of the polyelectrolyte, ?-TCP undergoes a complete transformation into OCP in 24h. The presence of polyacrylate in solution

A. Bigi; E. Boanini; R. Botter; S. Panzavolta; K. Rubini

2002-01-01

309

The Use of Lewis Acids During Rapid Steam Hydrolysis  

Microsoft Academic Search

Mixed hardwood chips were treated with various concentrations of aluminum chloride hexahydrate, aluminum sulfate hydrate, and ferric chloride and were subjected to rapid steam hydrolysis pretreatment (RASH). The three levels included 0.01, 0.03, and 0.05 moles of catalyst per 1000 grams of wood. Rapid steam hydrolysis (RASH) was done from 180° to 260°C at 20°C intervals for one minute. The

Jagdish Rughani; Louis Wasson; Gary McGinnis

1990-01-01

310

Dilute-acid hydrolysis of sugarcane bagasse at varying conditions  

Microsoft Academic Search

Sugarcane bagasse, a byproduct of the cane sugar industry, is an abundant source of hemicellulose that could be hydrolyzed\\u000a to yield a fermentation feedstock for the production of fuel ethanol and chemicals. The effects of sulfuric acid concentration,\\u000a temperature, time, and dry matter concentration on hemicellulose hydrolysis were studied with a 20-L batch hydrolysis reactor\\u000a using a statistical experimental design.

Markus Neureiter; Herbert Danner; Christiane Thomasser; Bamusi Saidi; Rudolf Braun

2002-01-01

311

Mild Nonoxidative Procedure for the Hydrolysis of Dimethylhydrazones  

Microsoft Academic Search

The past decade has seen amsiderable utilization of dkthylhyldrazones in organic synthesis. Their use as carbonyl equivalents depends on the ability of the practitioner to achieve hydrolylsis under mild conditions. Raagenta previously reported to acanplish this end include acid hydrolysis, methylation and hydrolysis, O3 , CH3C03H, NaI04 , Cu(OAc)2 , CoF3 , NOBF4 , MoF6 , MoOCl3 , UF6 ,

Robert E. Gawley; Enrico J. Termine

1982-01-01

312

On the Brønsted acid-catalyzed homogeneous hydrolysis of furans.  

PubMed

Furan affairs: Electronic structure calculations of the homogeneous Brønsted acid-catalyzed hydrolysis of 2,5-dimethylfuran show that proton transfer to the ?-position is rate-limiting and provides support that the hydrolysis follows general acid catalysis. By means of projected Fukui indices, we show this to be the case for unsubstituted, 2-, and 2,5-substituted furans with electron-donating groups. PMID:24006230

Nikbin, Nima; Caratzoulas, Stavros; Vlachos, Dionisios G

2013-11-01

313

Surfactant-enhanced alkaline flooding: Buffering at intermediate alkaline pH  

SciTech Connect

The alkaline flooding process involves injecting alkaline agents into the reservoir to produce more oil than is produced through conventional waterflooding. The interaction of the alkali in the flood water with the naturally occurring acids in the reservoir oil results in in-situ formation of soaps, which are partially responsible for lowering IFT and improving oil recovery. The extent to which IFT is lowered depends on the specific oil and injection water properties. Numerous investigators have attempted to clarify the relationship between system chemical composition and IFT. An experimental investigation of buffered alkaline flooding system chemistry was undertaken to determine the influence of various species present on interfacial tension (IFT) as a function of pH and ionic strength. IFT was found to go through an ultralow minimum in certain pH ranges. This synergism results from simultaneous adsorption of un-ionized and ionized acid species on the interface.

Rudin, J.; Wasan, D.T. (Illinois Inst. of Tech., Chicago, IL (United States))

1993-11-01

314

?-Glutamyl Hydrolase: Kinetic Characterization of Isopeptide Hydrolysis Using Fluorogenic Substrates†  

PubMed Central

?-Glutamyl hydrolase, a cysteine peptidase, catalyzes the hydrolysis of poly-?-glutamate derivatives of folate co-factors and many antifolate drugs. We have used internally quenched fluorogenic derivatives of glutamyl-?-glutamate and (4,4-difluoro)glutamyl-?-glutamate to examine the effect of fluorine substitution adjacent to the scissile isopeptide bond. Using a newly developed continuous fluorescence assay, the hydrolysis of both substrates could be described by Michaelis-Menten kinetics. Fluorine substitution resulted in a significant decrease in observed rates of hydrolysis under steady-state conditions due primarily to a ~ 15-fold increase in Km. Using stopped-flow techniques, hydrolysis of the non-fluorinated isopeptide was characterized by a burst phase followed by a steady-state rate, indicating that formation of the acyl enzyme is not rate-limiting for hydrolysis of this isopeptide. This conclusion was confirmed by analysis of the progress curves over a wide range of substrate concentration, which demonstrated that the acylation rate (k2) is ~ 10-fold higher than the deacylation rate (k3). The increased value of Km associated with the difluoro derivative limited the ability to obtain comparable pre-steady-state kinetics data at saturating concentration of substrate due to inner filter effects. However, even under non-saturating conditions, a modest burst was observed for the difluoro derivative. These data indicate that either deacylation or rearrangement of the enzyme-product complex is rate-limiting in this isopeptide hydrolysis reaction.

Alexander, Jessica P.; Ryan, Thomas J.; Ballou, David P.; Coward, James K.

2008-01-01

315

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.

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

2013-01-01

316

The effect of hydrolysis time on amino acid analysis.  

PubMed

Determining the amino acid content of a protein involves the hydrolysis of that protein, usually in acid, until the protein-bound amino acids are released and made available for detection. Both the variability in the ease of peptide bond cleavage and differences in the acid stability of certain amino acids can significantly affect determination of a protein's amino acid content. By using multiple hydrolysis intervals, a greater degree of accuracy can be obtained in amino acid analysis. Correction factors derived by linear extrapolation of serial hydrolysis data are currently used. Compartmental modeling of the simultaneous hydrolysis (yield) and degradation (decay) of amino acids by nonlinear multiple regression of serial hydrolysis data has also been validated and applied to determine the amino acid composition of various biological samples, including egg-white lysozyme, human milk protein, and hair. Implicit in the routine application of serial hydrolysis in amino acid analysis, however, is an understanding that correction factors, derived either linearly or through the more accurate nonlinear multiple regression approach, need to be determined for individual proteins rather than be applied uniformly across all protein types. PMID:16001867

Darragh, Alison J; Moughan, Paul J

2005-01-01

317

A MODELING STUDY ON HYDROLYSIS OF LACTOSE RECOVERED FROM WHEY AND ?-GALACTOSIDASE STABILITY UNDER SONIC TREATMENT  

Microsoft Academic Search

In the present study, the aim was to investigate the effect of ultrasonication on the kinetics of hydrolysis of lactose recovered from whey. The effects of the duty cycle, acoustic power of sonifier, reaction volume, and the hydrolysis products on hydrolysis degree as well as on enzyme stability were studied. The hydrolysis reactions were carried out in 25 mM phosphate buffer

Elçin Demirhan; Belma Özbek

2009-01-01

318

Shape relaxations in a fluid supported membrane during hydrolysis by phospholipase A 2  

Microsoft Academic Search

The behavior of a fluid supported membrane during hydrolysis by phospholipase A2 is for the first time visualized by time-resolved fluorescence imaging. After a lag phase, hydrolysis proceeds from the boundary of existing holes and via nucleation of new holes. During subsequent hydrolysis, the shape of the membrane boundary is determined both by hydrolysis and by shape relaxations due to

Uffe Bernchou Jensen; Adam Cohen Simonsen

2005-01-01

319

Electrode kinetics of antimony in alkaline solutions  

Microsoft Academic Search

The kinetics of the electro-oxidation and electro-reduction of Sb in alkaline solutions as well as the electrodeposition of Sb(III) on Sb have been studied. The rest potential follows the relation,E0=0.152–0.059 pHV is SHE which is the equation for the equilibrium potential for the redox reaction, 2Sb+60H-=Sb2O3+3H2O+6e- The rates of anodic dissolution and electro-reduction can be expressed by the following empirical

L. L. Wikstrom; Ken Nobe

1984-01-01

320

Hydrolysis and fractionation of lignocellulosic biomass  

DOEpatents

A multi-function process is described for the hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components such as extractives and proteins; a portion of the solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass comprising one or more of the following: optionally, as function 1, introducing a dilute acid of pH 1.0-5.0 into a continual shrinking bed reactor containing a lignocellulosic biomass material at a temperature of about 94 to about 160.degree. C. for a period of about 10 to about 120 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of extractives, lignin, and protein by keeping the solid to liquid ratio constant throughout the solubilization process; as function 2, introducing a dilute acid of pH 1.0-5.0, either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing either fresh biomass or the partially fractionated lignocellulosic biomass material from function 1 at a temperature of about 94-220.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of hemicellulosic sugars, semisoluble sugars and other compounds, and amorphous glucans by keeping the solid to liquid ratio constant throughout the solubilization process; as function 3, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 2 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process; and as function 4, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 3 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process.

Torget, Robert W. (Littleton, CO); Padukone, Nandan (Denver, CO); Hatzis, Christos (Denver, CO); Wyman, Charles E. (Lakewood, CO)

2000-01-01

321

Hydrolysis and fractionation of lignocellulosic biomass  

SciTech Connect

A multi-function process is described for the hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components such as extractives and proteins; a portion of the solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass comprising one or more of the following: optionally, as function 1, introducing a dilute acid of pH 1.0--5.0 into a continual shrinking bed reactor containing a lignocellulosic biomass material at a temperature of about 94 to about 160 C for a period of about 10 to about 120 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of extractives, lignin, and protein by keeping the solid to liquid ratio constant throughout the solubilization process; as function 2, introducing a dilute acid of pH 1.0--5.0, either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing either fresh biomass or the partially fractionated lignocellulosic biomass material from function 1 at a temperature of about 94--220 C for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of hemicellulosic sugars, semisoluble sugars and other compounds, and amorphous glucans by keeping the solid to liquid ratio constant throughout the solubilization process; as function 3, optionally, introducing a dilute acid of pH 1.0--5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 2 at a temperature of about 180--280 C for a period of about 10 to about 60 minutes at a volumetric flow rate of 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process; and as function 4, optionally, introducing a dilute acid of pH 1.0--5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 3 at a temperature of about 180--280 C for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process.

Torget, R.W.; Padukone, N.; Hatzis, C.; Wyman, C.E.

2000-02-08

322

Kinetics of catalyzed hydrolysis of 4-methylumbelliferyl caprylate (MUCAP) salmonella reagent  

NASA Astrophysics Data System (ADS)

The kinetics of chemical hydrolysis including neutral, acid- and base-catalyzed hydrolysis of 4-methylumbelliferyl caprylate (MUCAP) salmonella reagent were studied at different temperatures. The rate constants and activation parameters were determined by following the build-up of fluorescence peak of the hydrolysis product 4-methylumbelliferone (4-MU). The time scale of esterase enzyme hydrolysis caused by salmonella was compared with chemical hydrolysis as a background process.

Al-Kady, Ahmed S.; Ahmed, El-Sadat I.; Gaber, M.; Hussein, Mohamed M.; Ebeid, El-Zeiny M.

2011-09-01

323

Neutral alkaline-metal and alkaline-earth-metal derivatives of imidazole and benzimidazole.  

PubMed

A theoretical study of the minima and connecting transition states of the neutral complexes formed by alkaline-metal and alkaline-earth-metal derivatives of imidazolate and benzimidazolate anions has been carried out using B3LYP/6-31+G(d,p), B3LYP/6-311+G(3df,2p), and G3B3 methods. Two and three nondegenerated minima and two and four TS structures have been identified for imidazole and benzimidazole derivatives, respectively. The most stable minima of the alkaline-metal derivatives of both systems correspond to the metal interacting with the imidazole ring, whereas in the alkaline-earth-metal derivatives, the preferred minima depend on the substituent. A remarkable feature of some minima is the fact that some of the metal-aromatic interactions follow the classical ?-cation pattern, even though the global structure corresponds to a neutral salt, constituting a class of noncovalent interaction of great interest in the chemistry of aromatic and heterocyclic complexes. A CSD search has confirmed that the two bonding modes, N-? and ?, are present in the solid phase. The ? mode has been analyzed by comparison with other azoles. PMID:24844848

Blanco, Fernando; Lloyd, David G; Alkorta, Ibon; Elguero, José

2014-06-12

324

Zelfontlading van Alkaline en Leclanche Batterijen (Self-Discharge of Alkaline and Leclanche Batteries).  

National Technical Information Service (NTIS)

The self-discharge of Berec PP Leclanche and Duracell alkaline batteries was investigated. For this purpose the batteries were stored at 45C. After one year of storage at this temperature - corresponding with 5 years of storage at room temperature - the D...

C. A. van Beest P. P. M. M. Wittgen

1986-01-01

325

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

326

Intestinal alkaline phosphatase release is not associated with chylomicron formation.  

PubMed

Intestinal alkaline phosphatase (IAP) is one of the major sources of alkaline phosphatase in circulation. It is secreted into the intestinal lumen, serum, and lymph. After the ingestion of lipid, lymphatic alkaline phosphatase secretion increases significantly. We have found that the nonabsorbable fat olestra is unable to stimulate lymphatic alkaline phosphatase secretion. We also found that the hydrophobic surfactant Pluronic L-81, which blocks chylomicron formation, fails to inhibit this increase in lymphatic alkaline phosphatase secretion. These results suggest that it is the lipid uptake into the mucosa and/or reesterification to form triacylglycerols, but not the formation of chylomicrons, that is necessary for the stimulation of the secretion of alkaline phosphatase into the lymph. PMID:12466148

Nauli, Andromeda M; Zheng, Shuqin; Yang, Qing; Li, Ronggui; Jandacek, Ronald; Tso, Patrick

2003-04-01

327

Molecular modeling of human alkaline sphingomyelinase  

PubMed Central

Alkaline sphingomyelinase, which is expressed in the human intestine and hydrolyses sphingomyelin, is a component of the plasma and the lysosomal membranes. Hydrolase of sphingomyelin generates ceramide, sphingosine, and sphingosine 1-phosphate that have regulatory effects on vital cellular functions such as proliferation, differentiation, and apoptosis. The enzyme belongs to the Nucleotide Pyrophosphatase/Phosphodiesterase family and it differs in structural similarity with acidic and neutral sphingomyelinase. In the present study we modeled alkaline sphingomyelinase using homology modeling based on the structure of Nucleotide Pyrophosphatase/Phosphodiesterase from Xanthomonas axonopodis with which it shares 34% identity. Homology modeling was performed using Modeller9v7. We found that Cys78 and Cys394 form a disulphide bond. Further analysis shows that Ser76 may be important for the function of this enzyme, which is supported by the findings of Wu et al. (2005), that S76F abolishes the activity completely. We found that the residues bound to Zn2+ are conserved and geometrically similar with the template. Molecular Dynamics simulations were carried out for the modeled protein to observe the effect of Zinc metal ions. It was observed that the metal ion has little effect with regard to the stability but induces increased fluctuations in the protein. These analyses showed that Zinc ions play an important role in stabilizing the secondary structure and in maintaining the compactness of the active site.

Suresh, Panneer Selvam; Olubiyi, Olujide; Thirunavukkarasu, Chinnasamy; Strodel, Birgit; Kumar, Muthuvel Suresh

2011-01-01

328

Advanced inorganic separators for alkaline batteries  

NASA Technical Reports Server (NTRS)

A flexible, porous battery separator comprising a coating applied to a porous, flexible substrate is described. The coating comprises: (1) a thermoplastic rubber-based resin which is insoluble and unreactive in the alkaline electrolyte; (2) a polar organic plasticizer which is reactive with the alkaline electrolyte to produce a reaction product which contains a hydroxyl group and/or a carboxylic acid group; and (3) a mixture of polar particulate filler materials which are unreactive with the electrolyte, the mixture comprising at least one first filler material having a surface area of greater than 25 meters sq/gram, at least one second filler material having a surface area of 10 to 25 sq meters/gram, wherein the volume of the mixture of filler materials is less than 45% of the total volume of the fillers and the binder, the filler surface area per gram of binder is about 20 to 60 sq meters/gram, and the amount of plasticizer is sufficient to coat each filler particle. A method of forming the battery separator is also described.

Sheibley, D. W. (inventor)

1982-01-01

329

Solubility of uranium in alkaline salt solutions  

SciTech Connect

The solubility of uranium in alkaline salt solutions was investigated to screen for significant factors and interactions among the major salt components and temperature. The components included in the study were the sodium salts of hydroxide, nitrate, nitrite, aluminate, sulfate, and carbonate. General findings from the study included: (1) uranium solubilities are very low (1-20 mg/L) for all solution compositions at hydroxide concentrations from 0.1 to 17 molar (2) carbonate, sulfate, and aluminate are not effective complexants for uranium at high hydroxide concentration, (3) uranium solubility decreases with increasing temperature for most alkaline salt solutions, and (4) uranium solubility increases with changes in solution chemistry that reflect aging of high level waste (increase in nitrite and carbonate concentrations, decrease in nitrate and hydroxide concentrations). A predictive model for the concentration of uranium as a function of component concentrations and temperature was fitted to the data. All of the solution components and temperature were found to be significant. There is a significant lack of fit for the model, which suggests that the dependence on the uranium solubility over the wide range of solution compositions is non-linear and/or that there are other uncontrolled parameters which are important to the uranium solubility.

Hobbs, D.T.; Edwards, T.B.

1994-03-29

330

Spectroscopic characterization of alkaline earth uranyl carbonates  

SciTech Connect

A series of alkaline uranyl carbonates, M[UO{sub 2}(CO{sub 3}){sub 3}].nH{sub 2}O (M=Mg{sub 2}, Ca{sub 2}, Sr{sub 2}, Ba{sub 2}, Na{sub 2}Ca, 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{sub 2}[UO{sub 2}(CO{sub 3}){sub 3}].6H{sub 2}O was obtained for the first time. The EXAFS analysis showed that this compound consists of (UO{sub 2})(CO{sub 3}){sub 3} clusters similar to the other alkaline earth uranyl carbonates. The average U-Ba distance is 3.90+/-0.02A.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 [Institute of Nuclear Chemistry, Johannes Gutenberg-Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Reich, Tobias [Institute of Nuclear Chemistry, Johannes Gutenberg-Universitaet Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany)]. E-mail: tobias.reich@uni-mainz.de; Arnold, Thuro [Forschungszentrum Rossendorf e.V., Institute of Radiochemistry, P.O. Box 510119, 01314 Dresden (Germany); Geipel, Gerhard [Forschungszentrum Rossendorf e.V., Institute of Radiochemistry, P.O. Box 510119, 01314 Dresden (Germany); Bernhard, Gert [Forschungszentrum Rossendorf e.V., Institute of Radiochemistry, P.O. Box 510119, 01314 Dresden (Germany)

2005-02-15

331

Effects of enzyme loading and ?-glucosidase supplementation on enzymatic hydrolysis of switchgrass processed by leading pretreatment technologies.  

PubMed

The objective of this work is to investigate the effects of cellulase loading and ?-glucosidase supplementation on enzymatic hydrolysis of pretreated Dacotah switchgrass. To assess the difference among various pretreatment methods, the profiles of sugars and intermediates were determined for differently treated substrates. For all pretreatments, 72 h glucan/xylan digestibilities increased sharply with enzyme loading up to 25mg protein/g-glucan, after which the response varied depending on the pretreatment method. For a fixed level of enzyme loading, dilute sulfuric acid (DA), SO(2), and Lime pretreatments exhibited higher digestibility than the soaking in aqueous ammonia (SAA) and ammonia fiber expansion (AFEX). Supplementation of Novozyme-188 to Spezyme-CP improved the 72 h glucan digestibility only for the SAA treated samples. The effect of ?-glucosidase supplementation was discernible only at the early phase of hydrolysis where accumulation of cellobiose and oligomers is significant. Addition of ?-glucosidase increased the xylan digestibility of alkaline treated samples due to the ?-xylosidase activity present in Novozyme-188. PMID:21507624

Pallapolu, Venkata Ramesh; Lee, Y Y; Garlock, Rebecca J; Balan, Venkatesh; Dale, Bruce E; Kim, Youngmi; Mosier, Nathan S; Ladisch, Michael R; Falls, Matthew; Holtzapple, Mark T; Sierra-Ramirez, Rocio; Shi, Jian; Ebrik, Mirvat A; Redmond, Tim; Yang, Bin; Wyman, Charles E; Donohoe, Bryon S; Vinzant, Todd B; Elander, Richard T; Hames, Bonnie; Thomas, Steve; Warner, Ryan E

2011-12-01

332

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

333

Hydrolysis of N-alkyl sulfamates and the catalytic efficiency of an S-N cleaving sulfamidase.  

PubMed

The final step in the degradation of heparin sulfate involves the enzymatic hydrolysis of its 2-sulfamido groups. To evaluate the power of the corresponding sulfamidases as catalysts, we examined the reaction of N-neopentyl sulfamate at elevated temperatures and found it to undergo specific acid catalyzed hydrolysis even at alkaline pH. A rate constant of 10(-16) s(-1) was calculated using the Eyring equation for water attack on the N-protonated species at pH 7, 25 °C. As a model for the pH neutral reaction, a rate constant for hydroxide attack on (CH(3))(3)CCH(2)N(+)H(2)SO(3)(-) at pH 7, 25 °C was calculated to be 10(-19) s(-1). The corresponding rate enhancement (k(cat)/k(non)) produced by the N-sulfamidase of F. heparinum is approximately 10(16)-fold, which is somewhat larger than those generated by most hydrolytic enzymes but considerably smaller than those generated by S-O cleaving sulfatases. PMID:22352783

Lohman, Danielle C; Wolfenden, Richard; Edwards, David R

2012-03-16

334

A ?-glucan from the alkaline extract of a somatic hybrid (PfloVv5FB) of Pleurotus florida and Volvariella volvacea: structural characterization and study of immunoactivation.  

PubMed

A water soluble polysaccharide isolated from the alkaline extract of the somatic hybrid mushroom (PfloVv5FB), obtained through protoplast fusion between Pleurotus florida and Volvariella volvacea strains was found to contain d-glucose only. Structural investigation was carried out using acid hydrolysis, methylation analysis; periodate oxidation, and NMR studies ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HSQC, and HMBC). On the basis of the above mentioned experiments the structure of the repeating unit of the polysaccharide was established as: This polysaccharide exhibited strong immunoactivation of macrophages, splenocytes as well as thymocytes. PMID:23419942

Maity, Kankan K; Patra, Sukesh; Dey, Biswajit; Bhunia, Sanjoy K; Mandal, Soumitra; Bahera, Birendra; Maiti, Tapas K; Sikdar, Samir R; Islam, Syed S

2013-04-01

335

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

336

Post-steam alkaline flooding using buffer solutions  

SciTech Connect

An enhanced oil recovery process is described for formations that have been subjected to steam flooding, the process comprising: injecting into the formation an alkaline solution having a pH of less than 10, wherein the alkaline solution contains a substantially neutral salt; injecting a non-condensible gas into the formation to form in-situ foams for mobility control; and recovering oil displaced by the alkaline solution and gas.

Ziegler, V.M.

1989-03-21

337

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.

338

Role of oxidative enzymatic treatments on enzymatic hydrolysis of softwood.  

PubMed

The impact of oxidative modification and partial removal of lignin by laccase-mediator treatments on the enzymatic hydrolysis of steam-pretreated softwood (SPS) was evaluated. Two mediators, N-hydroxy-N-phenylacetamide (NHA) and its acetylated precursor, were oxidized by the laccase from Trametes hirsuta, and their effects on the activity of cellulolytic enzymes and on the hydrolysis yield of SPS were examined. Both simultaneous and sequential combinations of laccase-mediator treatments with commercial cellulases increased the sugar yield in the enzymatic hydrolysis of SPS. The maximal increase was 21% when a sequential treatment was applied. Laccase treatment alone was also shown to improve hydrolysis. NHA oxidized by laccase inhibited significantly the cellulases of Trichoderma reesei, but the presence of the solid substrate protected the activities against oxidative inactivation. Surface analysis of the lignocellulosic substrate before and after the laccase and cellulase treatments revealed an enrichment of lignin and an increase of carboxylic groups on the surface of the hydrolysis residue. PMID:15129438

Palonen, Hetti; Viikari, Liisa

2004-06-01

339

Lanthanide ions promote the hydrolysis of 2,3-bisphosphoglycerate.  

PubMed

The 31P NMR studies showed that lanthanide ions promote the site-specific hydrolysis of 2,3-Bisphosphoglycerate (BPG) at pH 7.4 by cleaving the 2' phosphomonoester bond. The effect of fourteen trivalent lanthanide ions and Sc3+, and Y3+ were compared by the percentage of hydrolysis obtained by determining the inorganic phosphate produced. All the trivalent lanthanide ions promote the hydrolysis, but Sc3+ not. Among them, Ce3+ affects the reaction mostly. This was mainly attributed to the autooxidation of Ce3+ to Ce4+, since the promoting effect of Ce3+ is related to the increasing Ce4+ amount in the solution and depressed by adding sulphite. Ce4+ promotes the hydrolysis more efficiently than Ce3+ do. The pseudo first-order rate constant for the hydrolysis of BPG by Ce(SO4)2 (18.7 mM) at pH 1 and pH 2, 37 degrees C is 3.1 h(-1) and 0.65 h(-1) respectively. A mechanism with a hydroxo species as reactive intermediate was proposed for the trivalent lanthanide ions. The site-specificity was explainable by this mechanism. PMID:15259363

Zhu, Bing; Xue, Deping; Wang, Kui

2004-08-01

340

Acid hydrolysis of corn stover in a concentrated slurry system  

SciTech Connect

The objective of this research was to characterize the hydrolysis kinetics of corn stover using sulfuric acid as the catalyst in a concentrated slurry. The kinetic data were obtained in a specially constructed continuous flow reactor with an in-line sampling system. The scope and range of experimental variables included temperature, acid concentration, liquid-to-solid ratio and reaction time. It is found that glucan hydrolysis follows a zero order kinetic in the range of experimental variables investigated. Both acid concentration and temperature increase the rate of glucan hydrolysis. A rate expression for glucan hydrolysis is developed both on the basis of adsorbed acid and bulk acid concentration. A kinetic model is proposed for the reaction. An integral approach is used to determine the parameters in the kinetic model and their numerical values are found to be comparable to those reported in the literature. It is found that at a given temperature, acid concentration and glucan conversion, there is an optimum liquid-to-solid ratio which maximizes glucose concentration. It is shown experimentally that glucan hydrolysis is not mass transfer limited at as low a liquid-to-solid ratio as 2:5:1.

Teng, K.F.

1984-01-01

341

Enzymatic hydrolysis of fructans in the tequila production process.  

PubMed

In contrast to the hydrolysis of reserve carbohydrates in most plant-derived alcoholic beverage processes carried out with enzymes, agave fructans in tequila production have traditionally been transformed to fermentable sugars through acid thermal hydrolysis. Experiments at the bench scale demonstrated that the extraction and hydrolysis of agave fructans can be carried out continuously using commercial inulinases in a countercurrent extraction process with shredded agave fibers. Difficulties in the temperature control of large extraction diffusers did not allow the scaling up of this procedure. Nevertheless, batch enzymatic hydrolysis of agave extracts obtained in diffusers operating at 60 and 90 degrees C was studied at the laboratory and industrial levels. The effects of the enzymatic process on some tequila congeners were studied, demonstrating that although a short thermal treatment is essential for the development of tequila's organoleptic characteristics, the fructan hydrolysis can be performed with enzymes without major modifications in the flavor or aroma, as determined by a plant sensory panel and corroborated by the analysis of tequila congeners. PMID:19473003

Avila-Fernández, Angela; Rendón-Poujol, Xóchitl; Olvera, Clarita; González, Fernando; Capella, Santiago; Peña-Alvarez, Araceli; López-Munguía, Agustín

2009-06-24

342

Effects of enzymatic hydrolysis of buckwheat protein on antigenicity and allergenicity  

PubMed Central

BACKGROUND/OBJECTIVES Due to its beneficial health effects, use of buckwheat has shown a continuous increase, and concerns regarding the allergic property of buckwheat have also increased. This study was conducted for evaluation of the hydrolytic effects of seven commercial proteases on buckwheat allergens and its allergenicity. MATERIALS/METHODS Extracted buckwheat protein was hydrolyzed by seven proteolytic enzymes at individual optimum temperature and pH for four hours. Analysis was then performed using SDS-PAGE, immunoblotting, and competitive inhibition ELISA (ciELISA) with rabbit antiserum to buckwheat protein, and direct ELISA with pooled serum of 21 buckwheat-sensitive patients. RESULTS Alkaline protease, classified as serine peptidase, was most effective in reducing allergenicity of buckwheat protein. It caused decomposition of the whole buckwheat protein, as shown on SDS-PAGE, and results of immunoblotting showed that the rabbit antiserum to buckwheat protein no longer recognized it as an antigen. Allergenicity showed a decrease of more than 50% when pooled serum of patients was used in ELISA. Two proteolytic enzymes from Aspergillus sp. could not hydrolyze buckwheat allergens effectively, and the allergenicity even appeared to increase. CONCLUSIONS Serine-type peptidases appeared to show a relatively effective reduction of buckwheat allergenicity. However, the antigenicity measured using rabbit antiserum did not correspond to the allergenicity measured using sera from human patients. Production of less allergenic buckwheat protein may be possible using enzymatic hydrolysis.

Sung, Dong-Eun; Lee, Jeongok; Han, Youngshin; Shon, Dong-Hwa; Ahn, Kangmo

2014-01-01

343

Digestive Alkaline Proteases from Zosterisessor ophiocephalus, Raja clavata, and Scorpaena scrofa: Characteristics and Application in Chitin Extraction.  

PubMed

The aim of this work was to study some biochemical characteristics of crude alkaline protease extracts from the viscera of goby (Zosterisessor ophiocephalus), thornback ray (Raja clavata), and scorpionfish (Scorpaena scrofa), and to investigate their applications in the deproteinization of shrimp wastes. At least four caseinolytic proteases bands were observed in zymogram of each enzyme preparation. The optimum pH for enzymatic extracts activities of Z. ophiocephalus, R. clavata, and S. scrofa were 8.0-9.0, 8.0, and 10.0, respectively. Interestingly, all the enzyme preparations were highly stable over a wide range of pH from 6.0 to 11.0. The optimum temperatures for enzyme activity were 50°C for Z. ophiocephalus and R. clavata and 55°C for S. scrofa crude alkaline proteases. Proteolytic enzymes showed high stability towards non-ionic surfactants (5% Tween 20, Tween 80, and Triton X-100). In addition, crude proteases of S. scrofa, R. clavata, and Z. ophiocephalus were found to be highly stable towards oxidizing agents, retaining 100%, 70%, and 66%, respectively, of their initial activity after incubation for 1?h in the presence of 1% sodium perborate. They were, however, highly affected by the anionic surfactant SDS. The crude alkaline proteases were tested for the deproteinization of shrimp waste in the preparation of chitin. All proteases were found to be effective in the deproteinization of shrimp waste. The protein removals after 3?h of hydrolysis at 45°C with an enzyme/substrate ratio (E/S) of 10 were about 76%, 76%, and 80%, for Z. ophiocephalus, R. clavata, and S. scrofa crude proteases, respectively. These results suggest that enzymatic deproteinization of shrimp wastes by fish endogenous alkaline proteases could be applicable to the chitin production process. PMID:22312476

Nasri, Rim; Younes, Islem; Lassoued, Imen; Ghorbel, Sofiane; Ghorbel-Bellaaj, Olfa; Nasri, Moncef

2011-01-01

344

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

345

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

346

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

347

Designer xylanosomes: protein nanostructures for enhanced xylan hydrolysis.  

PubMed

This work reports the successful design, construction, and application of multi-functional, self-assembling protein complex, termed xylanosomes. Using the architecture of cellulosomes as template, these structures were designed specifically for hemicellulose hydrolysis. Four different xylanosomes were developed, with up to three different hemicellulase activities combined into a single structure. Each xylanosome was composed of two native or chimeric hemicellulases and tested on wheat arabinoxylan or destarched corn bran for enzymatic hydrolysis. After 24-h incubation, soluble sugars released from arabinoxylan increased up to 30 % with xylanosomes containing a xylanase and bi-functional arabinofuranosidase/xylosidase over the corresponding free, unstructured enzymes. Additionally, xylanosomes with a xylanase and a ferulic acid esterase removed between 15 and 20 % more ferulic acid from wheat arabinoxylan than free enzymes. Furthermore, xylanosomes exhibited synergy with cellulases on destarched corn bran, suggesting a possible use of these nanostructures in cellulose hydrolysis. PMID:22555497

McClendon, Shara D; Mao, Zichao; Shin, Hyun-Dong; Wagschal, Kurt; Chen, Rachel R

2012-06-01

348

Extracellular alkaline-acid-alkaline transients in the rat spinal cord evoked by peripheral stimulation.  

PubMed

Regional differences in extracellular pH (pHe) were found in unstimulated rat spinal cord using double-barrel pH-sensitive microelectrodes. The pHe in the lower dorsal horn (laminae III-VII) was about 7.15, i.e. by about 0.2 pH units lower than that measured in the cerebrospinal fluid. Transient acid shifts in pHe by 0.01-0.05 pH units were found when acute nociceptive stimuli (pinch, press, heat) were applied to the hind paw. Chemical or thermal injury evoked by subcutaneous injection of turpentine or by application of 1-3 ml of hot oil onto the hindpaw produced a long-term decrease in pHe base line in the lower dorsal horn by about 0.05-0.1 pH units. The decrease in pHe began 2-10 min after injury and persisted for more than 2 h. Electrical nerve stimulation (10-100 Hz, 20-60 s) elicited biphasic (acid-alkaline) or triphasic (alkaline-acid-alkaline) changes in pHe which have a similar depth profile as the concomitantly recorded increase in [K+]e. An initial alkaline shift by about 0.005 pH units was found to be significantly decreased by La3+, an H+ channel blocker. The dominating acid shift by about 0.1-0.2 pH units was accelerated and increased by acetazolamide (carbonic anhydrase inhibitor) showing that the high buffering capacity of the extracellular fluid may hamper the resolution of acid perturbations. Stimulation-evoked acid shifts were blocked by amiloride, SITS, DIDS and La3+ and therefore have a complex mechanism which includes Na+/H+ exchange, Cl-/HCO3- cotransport and/or Na+/Cl-/H+/HCO3- antiport and H+ efflux through voltage-sensitive H+ channels. The poststimulation alkaline shift (alkaline undershoot) was blocked by ouabain and reflects coupled clearance of K+ and H+ by active transport processes. PMID:2354355

Syková, E; Svoboda, J

1990-04-01

349

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

350

Rechargeable alkaline manganese dioxide/zinc batteries  

NASA Astrophysics Data System (ADS)

The rechargeable alkaline manganese dioxide/zinc MnO 2/Zn) system, long established commercial as a primay battery, has reached a high level of performance as a secondary battery system. The operating principles are presented and the technological achievements are surveyed by referencing the recent publications and patent literature. A review is also given of the improvements obtained with newly formulated cathodes and anodes and specially designed batteries. Supported by modelling of the cathode and anode processes and by statistical evidence during cycling of parallel/series-connected modules, the envisioned performance of the next generation of these batteries is described. The possibility of extending the practical use of the improved rechargeable MnO 2/Zn system beyond the field of small electronics into the area of power tools, and even to kW-sized power sources, is demonstrated. Finally, the commercial development in comparison with other rechargeable battery systems is examined.

Kordesh, K.; Weissenbacher, M.

351

Alkaline phosphatase activity of coral reef benthos  

NASA Astrophysics Data System (ADS)

Alkaline Phosphatase (AP-ase) activity was measured for a variety of benthic algae and a community of reef organisms. Algae with epiphytic bacteria showed a higher AP-ase activity than algae without bacteria (11.6 ?mol P g-1 h-1 vs. 1.9?mol P g-1h-1). AP-ase activity associated with the benthos was estimated to be in the range of 10 100 mmol P m-2d-1, at least 1000 Cold greater than reported activity in the water column. Enzyme activity of reef benthos at saturated organic phosphate (P) substrate concentrations was sufficiently high that P uptake from organic substrates could be as fast as inorganic P uptake. Organic P compounds may be important in P recycling, but there is no evidence that organic P represents a significant new source of P to coral reefs.

Atkinson, M. J.

1987-10-01

352

Corrosion of platinum catalyst in alkaline solutions  

NASA Astrophysics Data System (ADS)

The corrosion behavior, as affected by time and potential, of platinum black in alkaline solution at 20 and 70 °C has been studied. It is shown that over the potential range 0.85 - 1.37 V platinum undergoes dissolution, the maximum corrosion rate being observed at E = 0.93 - 0.95 V. With time, the corrosion current decreases to 10 -6-10 -7 A/m 2. When platinum passes into solution the complex ion [Pt(OH) 6] 2- is formed. The influence of platinum pretreatment, leading to removal of surface oxygen compounds, on the rate of corrosion has been investigated. It has been found that Ba 2+ ions slow down the dissolution process, while Cl - ions increase its rate. The relationship between the platinum corrosion process and the shift of the oxygen electrode potential from the equilibrium value is discussed. Some conclusions are drawn about the mechanism of platinum corrosion.

Bagotzky, V. S.; Khrushcheva, E. I.; Tarasevich, M. R.; Shumilova, N. A.

353

Alkaline dechlorination of chlorinated volatile organic compounds  

SciTech Connect

The vast majority of contaminated sites in the United States and abroad are contaminated with chlorinated volatile organic compounds (VOCs) such as trichloroethylene (TCE), trichloroethane (TCA), and chloroform. These VOCs are mobile and persistent in the subsurface and present serious health risks at trace concentrations. The goal of this project was to develop a new chemical treatment system that can rapidly and effectively degrade chlorinated VOCs. The system is based on our preliminary findings that strong alkalis such as sodium hydroxide (NaOH) can absorb and degrade TCE. The main objectives of this study were to determine the reaction rates between chlorinated VOCs, particularly TCE, and strong alkalis, to elucidate the reaction mechanisms and by-products, to optimize the chemical reactions under various experimental conditions, and to develop a laboratory bench- scale alkaline destruction column that can be used to destroy vapor- phase TCE.

Gu, B.; Siegrist, R.L.

1996-06-01

354

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

355

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

356

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

357

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

358

Hydrolysis of sugarcane bagasse by mycelial biomass of Penicillium funiculosum  

SciTech Connect

Cellulose bioconversion has great promise for producing unlimited quantities of fermentable feedstocks and liquid fuels. Extensive studies on the production of extracellular cellulase and on the saccharification of various cellulosic substrates using cellulases have been reported. Use of mycelial biomass having cell bound cellulase for saccharification of cellulose was studied in Aspergillus terreus by Miller and Srinivasan. Extracellular cellulase production by P. funiculosum and its application for cellulose hydrolysis have been reported earlier by the authors. The present communication reports the hydrolysis of lignocellulose using mycelial biomass of P. funiculosum cultivated on cellulose and its reuse potential. 10 references.

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

1985-07-01

359

Hydrolysis for direct esterification of lipids from wet microalgae.  

PubMed

Hydrolysis of lipids from microalgae under high water content was investigated as a pretreatment of direct esterification. Results indicated that the hydrolysis process reduced the inhibition by water in FAME production; in addition, FAME obtained by esterification of hydrolysates was increased by 181.7% compared to FAME obtained by direct transesterification under the same amount of water content (80%). This method has great potential in terms of biodiesel production from microalgae since it uses no organic solvent, reduces the drying cost and lowers the operating cost compared to any other traditional method. PMID:23856586

Takisawa, Kenji; Kanemoto, Kazuyo; Miyazaki, Tatsuo; Kitamura, Yutaka

2013-09-01

360

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

361

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

362

ANNUAL REPORT. 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 the...

363

Solvent extraction of rhenium from molybdenum in alkaline solution  

Microsoft Academic Search

The technology of selective extraction of rhenium from alkaline solutions containing rhenium and molybdenum by solvent extraction using a mixture of tributyl phosphate and triotylamine as extractant has been investigated, complete separation of rhenium from alkaline solutions containing rhenium and molybdenum was possible after repeated extraction and repeated stripping. The results show that the mixture of 20% triotylamine and 30%

Cao Zhan-fang; Zhong Hong; Qiu Zhao-hui

2009-01-01

364

Performance of alkaline fuel cells: A possible future energy system?  

Microsoft Academic Search

Alkaline fuel cells (AFCs) are amongst the most mature fuel cell technologies having been in use since the mid 1960s by NASA in the Apollo and Space Shuttle programs. The AFC process is revisited to define current operating characteristics as the baseline for future developments of AFC technologies that can take advantage of advances in alkaline water electrolysers (AWEs). The

Betty Y. S. Lin; Donald W. Kirk; Steven J. Thorpe

2006-01-01

365

Alkalinity of the anoxic waters in the Western Black Sea  

Microsoft Academic Search

Measurements of total alkalinity and nutrients were made on samples from discrete depths, aboard the R\\/V Knorr, May 2001 in the Black Sea. Determination of macronutrient concentrations permits inclusion of these minor bases in alkalinity calculations and thus improved determination of the carbonate system. The permanent pycnocline maintains vertical separation of the oxic, suboxic and anoxic waters of the Black

William T. Hiscock; Frank J. Millero

2006-01-01

366

TOTAL ALKALINITY OF SURFACE WATERS OF THE US  

EPA Science Inventory

This map provides a synoptic illustration of the national patterns of surface water alkalinity in the conterminous United States. Alkalinity is the most readily available measure of the acid-neutralizing capacity of surface waters and provides a reasonable estimate o...

367

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

368

Thermometric Titration Analysis of Seawater for Chlorinity, Sulfate, and Alkalinity.  

National Technical Information Service (NTIS)

Total sulfate, chlorinity, and total alkalinity in seawater solutions have been determined by thermometric titration. The precision of the analyses was 0.3% for sulfate, 0.04% for chlorinity, and 0.1% for total alkalinity. Because of their simplicity, spe...

F. J. Millero, S. R. Schrager, L. D. Hansen

1973-01-01

369

Alkaline cleaner replacement for printed wiring board fabrication  

SciTech Connect

A replacement alkaline cleaning chemistry was qualified for the copper cleaning process used to support printed wiring board fabrication. The copper cleaning process was used to prepare copper surfaces for enhancing the adhesion of dry film photopolymers (photoresists and solder masks) and acrylic adhesives. The alkaline chemistry was used to remove organic contaminates such as fingerprints.

Goldammer, S.E.; Pemberton, S.E.; Tucker, D.R.

1997-04-01

370

Structural characterization of alkaline hydrogen peroxide pretreated grasses exhibiting diverse lignin phenotypes  

PubMed Central

Background For cellulosic biofuels processes, suitable characterization of the lignin remaining within the cell wall and correlation of quantified properties of lignin to cell wall polysaccharide enzymatic deconstruction is underrepresented in the literature. This is particularly true for grasses which represent a number of promising bioenergy feedstocks where quantification of grass lignins is particularly problematic due to the high fraction of p-hydroxycinnamates. The main focus of this work is to use grasses with a diverse range of lignin properties, and applying multiple lignin characterization platforms, attempt to correlate the differences in these lignin properties to the susceptibility to alkaline hydrogen peroxide (AHP) pretreatment and subsequent enzymatic deconstruction. Results We were able to determine that the enzymatic hydrolysis of cellulose to to glucose (i.e. digestibility) of four grasses with relatively diverse lignin phenotypes could be correlated to total lignin content and the content of p-hydroxycinnamates, while S/G ratios did not appear to contribute to the enzymatic digestibility or delignification. The lignins of the brown midrib corn stovers tested were significantly more condensed than a typical commercial corn stover and a significant finding was that pretreatment with alkaline hydrogen peroxide increases the fraction of lignins involved in condensed linkages from 88–95% to ~99% for all the corn stovers tested, which is much more than has been reported in the literature for other pretreatments. This indicates significant scission of ?-O-4 bonds by pretreatment and/or induction of lignin condensation reactions. The S/G ratios in grasses determined by analytical pyrolysis are significantly lower than values obtained using either thioacidolysis or 2DHSQC NMR due to presumed interference by ferulates. Conclusions It was found that grass cell wall polysaccharide hydrolysis by cellulolytic enzymes for grasses exhibiting a diversity of lignin structures and compositions could be linked to quantifiable changes in the composition of the cell wall and properties of the lignin including apparent content of the p-hydroxycinnamates while the limitations of S/G estimation in grasses is highlighted.

2012-01-01

371

Investigating the kinetics of paramagnetic-beads linked alkaline phosphatase enzyme through microchannel resistance measurement in dielectric microchip.  

PubMed

Real time monitoring of electrolyte resistance changes during hydrolysis of 4-nitrophenylphosphate (pNPP) by alkaline phosphatase (ALP) bound on paramagnetic-beads was performed into a small dielectric channel. The reaction kinetic fit with a non-competitive substrate-inhibition equation. Michaelis-Menten apparent constant, KM(app), was determined as 0.33±0.06mM and the maximum apparent rate, Vmax(app) as 98±5pMs(-1). The detection limits were 15fM for ALP and 0.75mM for pNPP. This miniaturized device constitutes a powerful tool for analysis of interaction between ligands. PMID:24613971

Faure, Mathilde; Sotta, Bruno; Gamby, Jean

2014-08-15

372

Effect of Zn(II) and Mg(II) on phosphohydrolytic activity of rat matrix-induced alkaline phosphatase.  

PubMed

Rat matrix-induced alkaline phosphatase is an enzyme which requires magnesium and zinc ions for its maximal activity. Two Zn(II) ions and one Mg(II) ion are bound to each subunit of native dimeric enzyme. The presence of magnesium ion (10-100 microM) or zinc ion (7-20 nM) alone is sufficient to stimulate apoenzyme activity. However maximal activity (264 U/mg) requires the presence of both ions. Binding of Zn(II) ions to the Mg(II) binding site causes a strong inhibition of the apoenzyme while the binding of Mg(II) on Zn(II) binding site is not sufficient to stimulate PNPPase activity of the apoenzyme. Binding of both ions to the enzyme molecule did not change the apparent dissociation constant for PNPP hydrolysis. PMID:2611837

Ciancaglini, P; Pizauro, J M; Grecchi, M J; Curti, C; Leone, F A

1989-01-01

373

Reduced activity of alkaline phosphatase due to host-guest interactions with humic superstructures.  

PubMed

Nuclear Magnetic Resonance (NMR) spectroscopy was applied to directly study the interactions between the alkaline phosphatase enzyme (AP) and two different humic acids from a volcanic soil (HA-V) and a Lignite deposit (HA-L). Addition of humic matter to enzyme solutions caused signals broadening in (1)H-NMR spectra, and progressive decrease and increase of enzyme relaxation (T1 and T2) and correlation (?C) times, respectively. Spectroscopic changes were explained with formation of ever larger weakly-bound humic-enzyme complexes, whose translational and rotational motion was increasingly restricted. NMR diffusion experiments also showed that the AP diffusive properties were progressively reduced with formation of large humic-enzyme complexes. The more hydrophobic HA-L affected spectral changes more than the more hydrophilic HA-V. (1)H-NMR spectra also showed the effect of progressively greater humic-enzyme complexes on the hydrolysis of an enzyme substrate, the 4-nitrophenyl phosphate disodium salt hexahydrate (p-NPP). While AP catalysis concomitantly decreased NMR signals of p-NPP and increased those of nitrophenol, addition of humic matter progressively and significantly slowed down the rate of change for these signals. In agreement with the observed spectral changes, the AP catalytic activity was more largely inhibited by HA-L than by HA-V. Contrary to previous studies, in which humic-enzyme interactions were only indirectly assumed from changes in spectrophotometric behavior of enzyme substrates, the direct measurements of AP behavior by NMR spectroscopy indicated that humic materials formed weakly-bound host-guest complexes with alkaline phosphatase, and the enzyme catalytic activity was thereby significantly inhibited. These results suggest that the role of extracellular enzymes in soils may be considerably reduced when they come in contact with organic matter dissolved in the soil solution. PMID:23953249

Mazzei, Pierluigi; Oschkinat, Hartmut; Piccolo, Alessandro

2013-11-01

374

Determination of the nitrogen content of nitrocellulose by capillary electrophoresis after alkaline denitration.  

PubMed

Nitrocellulose (NC) is a nitrate cellulose ester polymer whose nitrogen content determines its physical and chemical properties and its industrial applications. For the first time, capillary electrophoresis (CE) was used to quantify nitrite and nitrate ions released after the alkaline hydrolysis of NC to determine its nitrogen content. This article focuses on the development and validation of the CE method adapted to the determination of these anions in basic matrices in 3min total runtime. Molybdate anion was used as internal standard. The matrix effect in sodium hydroxide solution was statistically studied, demonstrating that no significant effect occurred in 0.5M sodium hydroxide solution. RSDs on normalized migration times (n=20) were 0.05% for both anions, while RSDs on normalized corrected areas (n=20) were 0.8% and 0.7% for nitrite and nitrate ions, respectively. The selectivity of the CE method was checked in the presence of 10 other anionic species potentially present in post-blast residues. Excellent linearities for normalized corrected areas (R(2)>0.999, residual standard deviations of ca 0.05) were obtained for both anions in the range 5-100mgL(-1). Finally, the optimized CE method was successfully applied to calculate the denitration yields of two NC standards belonging to the non-explosive and explosive classes, and to determine the nitrogen content of a NC contained in a single-base gunpowder. CE, with its speed, low running costs, and simplicity of use, appears as a valuable alternative to ion chromatography for the nitrogen content determination of pure NCs and NC-based explosives, and more generally, for the determination of nitrite and nitrate ions in other highly alkaline matrices. PMID:24840430

Alinat, Elodie; Delaunay, Nathalie; Costanza, Christine; Archer, Xavier; Gareil, Pierre

2014-07-01

375

Combination of alkaline and microwave pretreatment for disintegration of meat processing wastewater sludge.  

PubMed

Meat processing wastewater sludge has high organic content but it is very slow to degrade in biological processes. Anaerobic digestion may be a good alternative for this type of sludge when the hydrolysis, known to be the rate-limiting step of biological sludge anaerobic degradation, could be eliminated by disintegration. This investigation deals with disintegration of meat processing wastewater sludge. Microwave (MW) irradiation and combined alkaline pretreatment and MW irradiation were applied to sludge for disintegration purposes. Disintegration performance of the methods was evaluated with disintegration degree based on total and dissolved organic carbon calculations (DD(TOC)), and the solubilization of volatile solids (S(VS)) in the pretreated sludge. Optimum conditions were found to be 140 degrees C and 30 min for MW irradiation using response surface methodology (RSM) and pH = 13 for combined pretreatment. While DD(TOC) was observed as 24.6% and 54.9, S(VS) was determined as 8.54% and 42.5% for MW pretreated and combined pretreated sludge, respectively. The results clearly show that pre-conditioning of sludge with alkaline pretreatment played an important role in enhancing the disintegration efficiency of subsequent MW irradiation. Disintegration methods also affected the anaerobic biodegradability and dewaterability of sludge. An increase of 23.6% in biogas production in MW irradiated sludge was obtained, comparing to the raw sludge at the end of the 35 days of incubation. This increase was observed as 44.5% combined pretreatment application. While MW pretreatment led to a little improvement of the dewatering performance of sludge, in combined pretreatment NaOH deteriorates the sludge dewaterability. PMID:23837322

Erden, G

2013-01-01

376

Quantum and classical dynamics simulations of ATP hydrolysis in solution  

PubMed Central

ATP hydrolysis is a key reaction in living cells that drives many cellular processes. The reaction, which involves gamma phosphate cleavage from ATP, converting it to ADP, has been suggested to occur via an associative or dissociative mechanism dependent upon the surrounding environment. Prior quantum chemical studies suffered from short simulation timescales failing to capture free energy contributions due to relaxation of the surrounding aqueous environment. We have developed a highly parallelized QM/MM implementation in the NAMD and OpenAtom simulation packages, using the dual grid, dual length scale method for combined plane-wave and Eular exponential spline-based QM/MM simulations. This approach, using message-driven parallel quantum and classical dynamics, permits sufficient timescale simulations for quantum chemical events such as ATP hydrolysis, and is found to accurately and reliably include the free energy contributions of solvent relaxation to hydrolysis. In this paper we describe the application of the dual grid, dual length plane-wave-based QM/MM method to study both the associative and dissociative mechanisms of ATP hydrolysis, accounting for the free energy contribution from solvent relaxation, as well as for the key role of Mg2+ in the reaction.

Harrison, Christopher B.; Schulten, Klaus

2012-01-01

377

A possible hydrolysis mechanism of ?-naphthyl acetate catalyzed by antibodies  

Microsoft Academic Search

The mechanism of ester hydrolysis has been extensively studied; however, the precise function of active-site residues in promoting catalysis is unclear. We describe here the structural models for the complex of a catalytic antibody Fv fragment with a phosphonate transition -state analogue, constructed by using gene cloning, sequencing and molecular modeling, mainly based on a known X-ray structure of a

Yu Ren Yuan; Zong Xiang Xia; Cui Hong Yang; Bing Hui Yang; Ming Yeh

1998-01-01

378

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...

379

Kinetic expression for hydrolysis of soluble starch by glucoamylase  

Microsoft Academic Search

As the hydrolysis of starch by glucoamylase proceeds with stepwise removal of glucose units from the nonreducing ends of the starch chain, the number of available substrate molecules is essentially unchanged in the course of the degradation. In view of this aspect, a simple practical kinetic expression, which consists of a modified Michaelis-Menten form with product inhibition, is presented for

Koichiro Kusunoki; K. Koel; Fumihide Shiraishi; Keiichi Kato; Mayumi Kai

1982-01-01

380

Hydrolysis of oligosaccharides over solid Acid catalysts: a review.  

PubMed

Mild fractionation/pretreatment processes are becoming the most preferred choices for biomass processing within the biorefinery framework. To further explore their advantages, new developments are needed, especially to increase the extent of the hydrolysis of poly- and oligosaccharides. A possible way forward is the use of solid acid catalysts that may overcome many current drawbacks of other common methods. In this Review, the advantages and limitations of the use of heterogeneous catalysis for the main groups of solid acid catalysts (zeolites, resins, carbon materials, clays, silicas, and other oxides) and their relation to the hydrolysis of model soluble disaccharides and soluble poly- and oligosaccharides are presented and discussed. Special attention is given to the hydrolysis of hemicelluloses and hemicellulose-derived saccharides into monosaccharides, the impact on process performance of potential catalyst poisons originating from biomass and biomass hydrolysates (e.g., proteins, mineral ions, etc.). The data clearly point out the need for studying hemicelluloses in?natura rather than in model compound solutions that do not retain the relevant factors influencing process performance. Furthermore, the desirable traits that solid acid catalysts must possess for the efficient hemicellulose hydrolysis are also presented and discussed with regard to the design of new catalysts. PMID:24616436

Vilcocq, Léa; Castilho, Paula C; Carvalheiro, Florbela; Duarte, Luís C

2014-04-01

381

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

382

Reaction mechanism for the acid-catalyzed hydrolysis of saccharose  

Microsoft Academic Search

1.A polarimetric study was made of the reaction for the hydrolysis of saccharose in inorganic acid solutions.2.The A-1 mechanism, on the assumption that saccharose is a base of the type of a Hammett indicator, does not describe the experimental data.

N. A. Khalturinskii; Yu. V. Moiseev; G. E. Zaikov

1972-01-01

383

Enzymatic hydrolysis of tannery fleshings using chicken intestine proteases  

Microsoft Academic Search

Chicken intestine and tannery fleshings, the major wastes from poultry and tannery industries posing wide disposal problems, are used in this study for the recovery of proteins through biodegradation. Chicken intestines have been investigated as a source of proteolytic and autolytic enzymes for the hydrolysis of tannery fleshings. A combination of tannery fleshings and chicken intestines at acidic pH, when

A. Annapurna Raju; C. Rose; N. Muralidhara Rao

1997-01-01

384

Hydrolysis of anandamide and eicosapentaenoic acid ethanolamide in mouse splenocytes.  

PubMed

The hydrolysis of anandamide has been studied in mouse splenocytes using tritiated anandamide analogs labeled in the acyl- or ethanolamide parts of the molecule. [3H]Anandamide undergoes rapid (t(1/2) = 2.5 min) uptake and hydrolysis, yielding ethanolamine and arachidonic acid. The anandamide hydrolysis in splenocytes is sensitive to inhibition by phenylmethylsulfonyl fluoride, and it is assumed that the observed activity is due to fatty acid amide hydrolase, which inactivates anandamide in central and peripheral tissues. Eicosapentaenoic acid ethanolamide and the 15-hydroxy-derivative of anandamide are shown to be amidohydrolase substrates as well. The fatty acids derived from hydrolytic cleavage of acylethanolamines undergo rapid oxidation by splenocyte lipoxygenase, yielding the corresponding 12-hydroxy-derivatives. Oxygenated ethanolamide derivatives were not found. The data suggest that polyenoic fatty acid ethanolamides are metabolic precursors of eicosanoids in splenocytes and that amide bond hydrolysis is the key point in switching of biological activity spectra between endocannabinoids and oxylipins. PMID:10851041

Bobrov, M Y; Shevchenko, V P; Yudushkin, I A; Rogov, S I; Remov, M N; Fomina-Ageeva, E V; Gretskaya, N M; Nagaev, I Y; Kuklev, D V; Bezuglov, V V

2000-05-01

385

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

386

Acid Hydrolysis Lignin as a Sorbent for Naphthalene  

Microsoft Academic Search

Lignin, a major polymeric constituent of woody plant tissue, is an abundant source of natural organic matter available as a waste product from the pulp and paper and the fuel ethanol industries. In this study, the sorptive capacity of acid hydrolysis lignin for naphthalene, a representative nonpolar hydrophobic organic compound (HOC), was investigated. When powdered lignin is mixed with distilled

ANGELA KEANE; SUBHASIS GHOSHAL

2001-01-01

387

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

388

Hydrolysis of native proteins by keratinolytic protease of Doratomyces microsporus  

Microsoft Academic Search

A keratinolytic protease from the fungus Doratomyces microsporus was investigated for its ability to hydrolyse different native proteins. The purified enzyme was incubated for up to 24h with keratinous substrates as well as with non-keratinous proteins. The results showed that the enzyme was broad specific since it hydrolysed various globular and fibrillar proteins. The hydrolysis of keratinous substrates decreased in

J Friedrich; S Kern

2003-01-01

389

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 ...

390

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

391

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

392

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

393

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

394

Catalytic hydrolysis of ammonia borane via cobalt palladium nanoparticles.  

PubMed

Monodisperse 8 nm CoPd nanoparticles (NPs) with controlled compositions were synthesized by the reduction of cobalt acetylacetonate and palladium bromide in the presence of oleylamine and trioctylphosphine. These NPs were active catalysts for hydrogen generation from the hydrolysis of ammonia borane (AB), and their activities were composition dependent. Among the 8 nm CoPd catalysts tested for the hydrolysis of AB, the Co(35)Pd(65) NPs exhibited the highest catalytic activity and durability. Their hydrolysis completion time and activation energy were 5.5 min and 27.5 kJ mol(-1), respectively, which were comparable to the best Pt-based catalyst reported. The catalytic performance of the CoPd/C could be further enhanced by a preannealing treatment at 300 °C under air for 15 h with the hydrolysis completion time reduced to 3.5 min. This high catalytic performance of Co(35)Pd(65) NP catalyst makes it an exciting alternative in pursuit of practical implementation of AB as a hydrogen storage material for fuel cell applications. PMID:21766875

Sun, Daohua; Mazumder, Vismadeb; Metin, Önder; Sun, Shouheng

2011-08-23

395

Synthesis of sepiapterin-C via hydrolysis of 6-ethynylpteridine.  

PubMed

Acid hydrolysis of 6-ethynylpteridine catalyzed by mercury oxide gives 6-acetyl-2-amino-3,4-dihydropteridin-4-one in good yield. Partial reduction of the product with dissolved Al in NH3 solution afforded sepiapterin-C. PMID:24660457

Nxumalo, Winston; Dinsmore, Andrew

2014-01-01

396

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

397

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

398

Hydrolysis of bile acid conjugates by selected fungi  

Microsoft Academic Search

Fungi which have been previously shown to hydrolyse glycocholic acid, with liberation of the free bile acid, have now been shown to be similarly capable of hydrolysing glycodeoxycholic acid. Sodium taurocholate, however, is much less susceptible and its hydrolysis has been demonstrated with only one of the selected fungi, Penicillium chrysogenum, growing in a medium containing the conjugate as the

R. Chong; I. S. Maddox; M. R. Johns; A. G. Wagenaar

1980-01-01

399

Pretreatment of poplar by acid and alkali for enzymatic hydrolysis  

Microsoft Academic Search

The dilute acid pretreatment in a plug flow reactor and alkali pretreatments with caustic solutions at different conditions followed by enzymatic hydrolysis resulted in drastically improved glucose yields for aspen and hybrid poplar. The acid pretreatment conditions must be carefully chosen to open the cellulosic structure allowing rapid diffusion of enzyme. The effectiveness of pretreatment is chiefly based on the

G. Ucar

1990-01-01

400

Acid hydrolysis of sweet potato for ethanol production  

SciTech Connect

Studies were conducted to establish optimal conditions for the acid hydrolysis of sweet potato for maximal ethanol yield. The starch contents of two sweet potato cultivars (Georgia Red and TG-4), based on fresh weight, were 21.1 +/- 0.6% and 27.5 +/- 1.6%, respectively. The results of acid hydrolysis experiments showed the following: (1) both hydrolysis rate and hydroxymethylfurfural (HMF) concentration were a function of HCL concentration, temperature, and time; (2) the reducing sugars were rapidly formed with elevated concentrations of HCl and temperature, but also destroyed quickly; and (3) HMF concentration increased significantly with the concentration of HCl, temperature, and hydrolysis time. Maximum reducing sugar value of 84.2 DE and 0.056% HMF (based on wet weight) was achieved after heating 8% SPS for 15 min in 1N HCl at 110/sup 0/C. Degraded 8% SPS (1N HCl, 97/sup 0/C for 20 min or 110/sup 0/C for 10 min) was utilized as substrate for ethanol fermentation and 3.8% ethanol (v/v) was produced from 1400 mL fermented wort. This is equal to 41.6 g ethanol (200 proof) from 400 g of fresh sweet potato tuber (Georgia Red) or an ethanol yield potential of 431 gal of 200-proof ethanol/acre (from 500 bushel tubers/acre).

Kim, K.; Hamdy, M.K.

1985-01-01

401

Batteries: from alkaline to zinc-air.  

PubMed

There is no perfect disposable battery--one that will sit on the shelf for 20 years, then continually provide unlimited current, at a completely constant voltage until exhausted, without producing heat. There is no perfect rechargeable battery--one with all of the above characteristics and will also withstand an infinite overcharge while providing an equally infinite cycle life. There are only compromises. Every battery selection is a compromise between the ideally required characteristics, the advantages, and the limitations of each battery type. General selection of a battery type to power a medical device is largely outside the purview of the biomed. Initially, these are engineering decisions made at the time of medical equipment design and are intended to be followed in perpetuity. However, since newer cell types evolve and the manufacturer's literature is fixed at the time of printing, some intelligent substitutions may be made as long as the biomed understands the characteristics of both the recommended cell and the replacement cell. For example, when the manufacturer recommends alkaline, it is usually because of the almost constant voltage it produces under the devices' design load. Over time, other battery types may be developed that will meet the intent of the manufacturer, at a lower cost, providing longer operational life, at a lower environmental cost, or with a combination of these advantages. In the Obstetrical Doppler cited at the beginning of this article, the user had put in carbon-zinc cells, and the biomed had unknowingly replaced them with carbonzinc cells. If the alkaline cells recommended by the manufacturer had been used, there would have been the proper output voltage at the battery terminals when the [table: see text] cells were at their half-life. Instead, the device refused to operate since the battery voltage was below presumed design voltage. While battery-type substitutions may be easily and relatively successfully made in disposable applications (for example, zinc-air for alkaline--if it is cost-effective), this is absolutely forbidden for secondary cells. Because of the differing cell voltages, charge characteristics and overcharge tolerance between different types of secondary cells, substituting a nickel-cadmium battery pack for the more expensive lithium-ion pack (if it is physically able to fit into the battery compartment), might appear to save money (e.g. $50 vs. $100) but it would be very ill advised. Since the cell characteristics are very different, it would be downright fatal to anyone within the 'kill radius' when the pack explodes. Those outside the kill radius would receive chemical burns from the electrolyte. Substitutions of secondary cell battery packs are generally not a good idea for biomeds to engage in. These are engineering decisions best left to either aftermarket battery pack manufacturers or the medical device manufacturer as a design engineering change. PMID:15106428

Dondelinger, Robert M

2004-01-01

402

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

403

40 CFR 721.9680 - Alkaline titania silica gel (generic name).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Alkaline titania silica gel (generic name). 721.9680... § 721.9680 Alkaline titania silica gel (generic name). (a) Chemical...generically as an alkaline titania silica gel (PMN P-95-529) is...

2010-07-01

404

40 CFR 721.9680 - Alkaline titania silica gel (generic name).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Alkaline titania silica gel (generic name). 721.9680... § 721.9680 Alkaline titania silica gel (generic name). (a) Chemical...generically as an alkaline titania silica gel (PMN P-95-529) is...

2009-07-01

405

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

Code of Federal Regulations, 2012 CFR

... false Hydrated alkaline earth metal salts of metalloid oxyanions. 721.4668...4668 Hydrated alkaline earth metal salts of metalloid oxyanions. (a) Chemical...identified as hydrated alkaline earth metal salts of metalloid oxyanions (PMN...

2012-07-01

406

Watershed versus In-Lake Alkalinity Generation: A Comparison of Rates Using Input-Output Studies.  

National Technical Information Service (NTIS)

As a means of assessing the relative contributions of watershed (terrestrial) and in-lake processes to overall lake/watershed alkalinity budgets, alkalinity production rates for watersheds and low alkalinity lakes were compiled from the literature and com...

P. W. Shaffer R. P. Hooper K. N. Eshleman M. R. Church

1988-01-01

407

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.

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

2001-01-01

408

Hydrolysis of solubilized hemicellulose derived from wet-oxidized wheat straw by a mixture of commercial fungal enzyme preparations.  

National Technical Information Service (NTIS)

The enzymatic hydrolysis of the solubilized hemicellulose fraction from wet-oxidized wheat straw was investigated for quantification purposes. An optimal hydrolysis depends on factors such as composition of the applied enzyme mixture and the hydrolysis co...

A. Skammelsen Schmidt A. B. Thomsen A. Woidemann M. Tenkanen

1998-01-01

409

Phospholipid Requirements of Ca++-Stimulated, Mg++-Dependent ATP Hydrolysis in Rat Brain Synaptic Membranes.  

National Technical Information Service (NTIS)

The phospholipid requirement for calcium ion-stimulated, magnesium ion -dependent (ATP) hydrolysis(Ca (++) /Mg (++)-ATPase) and Mg(++) -stimulated ATP hydrolysis (Mg(++)-ATPase) in rat brain synaptosomal membranes was studied employing partial delipidatio...

C. R. Gandhi D. H. Ross J. J. Valdes R. G. Thompson

1989-01-01

410

A kinetic study of hydrolysis of polyester elastomer in magnetic tape  

NASA Technical Reports Server (NTRS)

A useful method for kinetic study of the hydrolysis of polyester elastomer is established which uses the number-average molecular weight. The reasonableness of this method is confirmed and the effect of magnetic particles on hydrolysis is considered.

Yamamoto, K.; Watanabe, H.

1994-01-01

411

Dilute-Acid Hydrolysis of Cellulosic Materials III: Kinetics of a Lignocellulose Residue.  

National Technical Information Service (NTIS)

Kinetics of dilute-acid hydrolysis of lignocellulose residue from a furfural process is investigated experimentally. The rate constants are determined by a simplified method. By comparing with the kinetics of waste paper hydrolysis in similar conditions t...

V. J. Pohjola M. Pulkkinen P. Perttila

1977-01-01

412

Visible spectrophotometric determination of cephalosporins and penicillins by indophenol derivatization with and without alkaline degradation to ammonia.  

PubMed

Cephalosporins and penicillins give reproducible yields of ammonia on degradation in 0.5 M sodium hydroxide solution at 100 degrees C: the ammonia formed was determined in the degraded solutions using the indophenol reaction. In another approach the ammonia driven off on refluxing alkaline solutions of the cephalosporin or penicillin was collected in dilute hydrochloric acid solution and determined using the indophenol reaction. For eight of the fourteen cephalosporins and penicillins studied identical yields were recorded using the two procedures: these varied from 29% for penicillin G to 137% for cephalonium based on the production of one ammonia molecule per beta-lactam molecule. For six other cephalosporins the distillation method gave substantially higher yields of ammonia than did the direct determination. Eight cephalosporins and penicillins were found to give substantial indophenol-type reactions without prior hydrolysis of the beta-lactam, but the sensitivities were usually lower than for the hydrolysis method. Manual spectrophotometric procedures for the determination of cephalosporins and penicillins based on these reactions have been developed. PMID:16867666

Fogg, A G; Abdalla, M A

1985-01-01

413

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, III, C. A.

2005-01-01

414

Optimization of acid hydrolysis from the hemicellulosic fraction of Eucalyptus grandis residue using response surface methodology  

Microsoft Academic Search

Biotechnological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars. Hydrolysis can be performed enzymatically and with dilute or concentrate mineral acids. The present study used dilute sulfuric acid as a catalyst for hydrolysis of Eucalyptus grandis residue. The purpose of this paper was to optimize the hydrolysis process in a 1.4l pilot-scale

Eliana Vieira Canettieri; George Jackson de Moraes Rocha; João Andrade de Carvalho; João Batista de Almeida e Silva

2007-01-01

415

Effect of the extent of the hydrolysis of tetrabutoxytitanium on catalysis efficiency in the esterification reaction  

SciTech Connect

A study was carried out on the products of the hydrolysis of tetrabutoxytitanium and their catalytic activity in the esterification reaction. A maximum is observed in the dependence of the reaction rate constant on the extent of the hydrolysis of tetrabutoxytitanium. The maximum effective esterification rate constant corresponds to 60% hydrolysis of tetrabutoxytitanium. The hydrolysis products in this case have largely linear structure. The relationship between the catalytic activity of linear polytitanates and their stability in the reaction medium is discussed.

Chervina, S.I.; Maksimenko, E.G.; Barshtein, R.S.; Shabanova, N.V.; Bulai, A.K.; Kotov, Yu.I.; Slonim, I.Ya.

1988-03-01

416

Behaviour of southern red oak hemicelluloses and lignin in a mild sulfuric acid hydrolysis  

Microsoft Academic Search

Removal and modification of southern red oak hemicelluloses and lignin in a 0.05%(w\\/v) sulfuric acid hydrolysis were investigated. The hydrolysis profile was to raise the reaction from room temperature to 150 degrees C in 38 minutes and to extend the hydrolysis; 25.5% of red oak components were dissolved, of which 58% was xylose and 17% lignin. As the hydrolysis proceeded

A. V. Tran; R. P. Chambers

1986-01-01

417

Effects of Substrate Loading on Enzymatic Hydrolysis and Viscosity of Pretreated Barley Straw  

Microsoft Academic Search

In this study, the applicability of a “fed-batch” strategy, that is, sequential loading of substrate or substrate plus enzymes\\u000a during enzymatic hydrolysis was evaluated for hydrolysis of steam-pretreated barley straw. The specific aims were to achieve\\u000a hydrolysis of high substrate levels, low viscosity during hydrolysis, and high glucose concentrations. An enzyme system comprising\\u000a Celluclast and Novozyme 188, a commercial cellulase

Lisa Rosgaard; Pavle Andric; Kim Dam-Johansen; Sven Pedersen; Anne S. Meyer

2007-01-01

418

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.

Lee, H S; Sturm, A

1996-01-01

419

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

420

Engineering challenges of ocean alkalinity enhancement  

NASA Astrophysics Data System (ADS)

The addition of calcium oxide (CaO) to the ocean as a means of enhancing the capacity of the ocean as a carbon sink was first proposed by Haroon Kheshgi in 1995. Calcium oxide is created by heating high purity limestone in a kiln to temperatures of approximately 1000°C. Addition of this material to the ocean draws carbon dioxide out of the atmosphere (approximately 1 tonne of CaO could sequester 1.3 tonnes of CO2). Abiotic carbonate precipitation is inhibited in the surface ocean. This is a carbon and energy expensive process, where approximately 0.8 tonnes of CO2 are produced at a point source for every tonne sequestered. The feasibility of ocean alkalinity enhancement requires capture and storage of the point source of CO2. We present details of a feasibility study of the engineering challenges of Kheshgi's method focusing on the potential scalability and costs of the proposed process. To draw down a PgC per year would require the extraction and processing of ~6Pg of limestone per year, which is similar in scale to the current coal industry. Costs are estimated at ~USD30-40 per tonne of CO2 sequestered through the process, which is favourable to comparative processes. Kheshgi, H. (1995) Energy 20 (9) 915-922

Kruger, T.; Renforth, P.

2012-04-01

421

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

422

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

423

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

424

Arsenic removal by iron-doped activated carbons prepared by ferric chloride forced hydrolysis  

Microsoft Academic Search

Ferric chloride forced hydrolysis is shown to be a good method for increasing the iron content of activated carbons (ACs). Iron content increased linearly with hydrolysis time, and ACs with iron content as high as 9.4wt.% at 24h hydrolysis time could be prepared. The increase in iron content did not produce any modification in the textural parameters determined by nitrogen

V. Fierro; G. Muñiz; G. Gonzalez-Sánchez; M. L. Ballinas; A. Celzard

2009-01-01

425

Restriction of the enzymatic hydrolysis of steam-pretreated spruce by lignin and hemicellulose  

Microsoft Academic Search

The presence of lignin is known to reduce the efficiency of the enzymatic hydrolysis of lignocellulosic raw materials. On the other hand, solubilization of hemicellulose, especially of xylan, is known to enhance the hydrolysis of cellulose. The enzymatic hydrolysis of spruce, recognized among the most challenging lignocellulosic substrates, was studied by commercial and purified enzymes from Trichoderma reesei. Previously, the

Anikó Várnai; Matti Siika-aho; Liisa Viikari

2010-01-01

426

Pattern of enzyme hydrolysis in raw sago starch: effects of processing history  

Microsoft Academic Search

Hydrolysis patterns of five batches of sago starch were studied by using Novo Nordisk and Sigma ?-amylases and glucoamylases. Native sago starch was a poor substrate to the enzymes and the hydrolysis patterns were surface erosion, pitting and crevassing. After incubation with pH 3·5 acetate buffer at 60 °C for 2 h, the hydrolysis pattern was different: a single deep

W. J. Wang; A. D. Powell; C. G. Oates

1995-01-01

427

Process for preparing zinc powder for alkaline batteries  

SciTech Connect

A zinc powder having a low gas evolution in an alkaline electrolyte for use in an alkaline battery are obtained by alloying the zinc with at least one metal selected from the group consisting of lead, cadmium, thallium and indium and at least one further metal selected from the group consisting of lead, cadmium, thallium, indium gold, silver, tin and gallium. Thereby it is possible to avoid the use of mercury as an alloying element but nevertheless to obtain a zinc powder which meet all of the requirements for use in alkaline batteries.

Glaeser, W.

1985-10-22

428

Effect of alkaline pH-shift processing on in vitro gastrointestinal digestion of herring (Clupea harengus) fillets.  

PubMed

The effect of alkaline pH-shift processing on herring (Clupea harengus) protein oxidation, salt solubility and digestibility, has been evaluated. For the latter, herring mince and pH-shift produced herring protein isolate, both raw and heat-treated, were digested using a static gastrointestinal in vitro model. The pH-shift process resulted in drastically lowered protein salt solubility and increased lipid oxidation while protein carbonyl formation was unaffected. Yet, no significant differences in the degree of hydrolysis (DH) were observed between mince and isolates after completed gastrointestinal digestion, something which was confirmed by a similar release of proteinaceous material <3 kDa and similar free amino acid profiles. The polypeptide profiles of digested samples however revealed that two peptides (33 and 36 kDa) were present in larger amounts in the digested protein isolate compared to the digested herring mince. The results indicate that alkaline pH-shift processing had limited quantitative influence on the gastrointestinal digestibility of herring proteins despite its negative effects on protein salt solubility and lipid oxidation. PMID:23265479

Marmon, Sofia K; Undeland, Ingrid

2013-05-01

429

Enhanced coagulation for high alkalinity and micro-polluted water: the third way through coagulant optimization.  

PubMed

Conventional coagulation is not an effective treatment option to remove natural organic matter (NOM) in water with high alkalinity/pH. For this type of water, enhanced coagulation is currently proposed as one of the available treatment options and is implemented by acidifying the raw water and applying increased doses of hydrolyzing coagulants. Both of these methods have some disadvantages such as increasing the corrosive tendency of water and increasing cost of treatment. In this paper, an improved version of enhanced coagulation through coagulant optimization to treat this kind of water is demonstrated. A novel coagulant, a composite polyaluminum chloride (HPAC), was developed with both the advantages of polyaluminum chloride (PACl) and the additive coagulant aids: PACl contains significant amounts of highly charged and stable polynuclear aluminum hydrolysis products, which is less affected by the pH of the raw water than traditional coagulants (alum and ferric salts); the additives can enhance both the charge neutralization and bridging abilities of PACl. HPAC exhibited 30% more efficiency than alum and ferric salts in dissolved organic carbon (DOC) removal and was very effective in turbidity removal. This result was confirmed by pilot-scale testing, where particles and organic matter were removed synergistically with HPAC as coagulant by sequential water treatment steps including pre-ozonation, coagulation, flotation and sand filtration. PMID:18206207

Yan, Mingquan; Wang, Dongsheng; Qu, Jiuhui; Ni, Jinren; Chow, Christopher W K

2008-04-01

430

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.

431

The purification and activities of an alkaline protease of Aspergillus clavatus from Nigerian poultry feeds.  

PubMed

Optimal growth and extracellular protease production by Aspergillus clavatus Des. was recorded at 30 degrees C and between days 5 and 7 of the 8-day incubation period. Purification of this enzyme was achieved by a combination of ultrafiltration, alcoholic precipitation and fractionation on DEAE-cellulose and Sephadex-G.200. A single peak of an alkaline protease was subsequently obtained with a 9-fold increase in specific activity and a final recovery value of 26.2%. The enzyme had optimal activity at 37 degrees C and a pH of 7.8. The enzyme did not degrade leucine amide, hippurylphenylalanine and hippurylarginine indicating lack of exo-protease activity. However, endo-protease activity led to a rapid hydrolysis of gelatin with optimal activity at 40 degrees C and pH 7.8. The high incidence of A. clavatus on Nigerian poultry feeds vis-a-vis the potential health risks posed to farm animals is discussed. PMID:3534215

Ogundero, V W; Osunlaja, S O

1986-01-01

432

Thermostable alkaline halophilic-protease production by Natronolimnobius innermongolicus WN18.  

PubMed

This study reports the production and biochemical characterisation of a thermostable alkaline halophilic protease from Natronolimnobius innermongolicus WN18 (HQ658997), isolated from soda Lake of Wadi An-Natrun, Egypt. The enzyme was concentrated by spinning through a centriplus, centrifugal ultrafiltration Millipore membrane with a total yield of 25%. The relative molecular mass of this protease determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis ranged from 67 to 43 kDa. The extracellular protease of N. innermongolicus WN18 was dependent on high salt concentrations for activity and stability, and it had an optimum temperature of 60°C in the presence of 2.5 M NaCl. This enzyme was stable in a broad pH range (6-12) with an optimum pH of 9-10 for azocasein hydrolysis. This extracellular protease, therefore, could be defined as thermostable and haloalkaliphilic with distinct properties that make the enzyme applicable for different industrial purposes. PMID:24716669

Selim, Samy; Hagagy, Nashwa; Aziz, Mohamed Abdel; El-Meleigy, El Syaed; Pessione, Enrica

2014-09-01

433

Substrate specificity and thermostability of the dehairing alkaline protease from Bacillus pumilus.  

PubMed

An alkaline protease (DHAP) from Bacillus pumilus has shown great potential in hide dehairing. To get better insights on its catalytic properties for application, the substrate specificity and thermostability were investigated using five natural proteins and nine synthetic peptides. The results showed that DHAP could hydrolyze five proteins tested here in different specificity. Collagen, a component of animal skin, was more resistant to hydrolysis than casein, fibrin, and gelatin. Among the synthetic peptides, the enzyme showed activity mainly with tetrapeptide substrates with the catalytic efficiency in order of Phe>Leu>Ala at P1 site, although k(m) value for AAVA-pN is much lower than that for AAPL-pN and AAPF-pN. With tripeptide substrates, smaller side-chain group (Gly) at P1 site was not hydrolyzed by DHAP. The enzyme showed good thermostability below 60 degrees C, and lost activity so quickly above 70 degrees C. The thermostability was largely dependent on metal ion, especially Ca(2+), although other ions, like Mg(2+), Mn(2+), and Co(2+), could sustain stability at certain extent within limited time. Cu(2+), Fe(2+), as well as Al(3+), did not support the enzyme to retain activity at 60 degrees C even in 5 min. In addition, the selected metal ions could coordinate calcium in improvement or destruction of thermostability for DHAP. PMID:19132554

Wan, Min-Yuan; Wang, Hai-Yan; Zhang, Yi-Zheng; Feng, Hong

2009-11-01

434

Conjugated polyelectrolyte-based real-time fluorescence assay for alkaline phosphatase with pyrophosphate as substrate.  

PubMed

The fluorescence of the anionic, carboxylate-substituted poly(phenylene ethynylene) polymer PPECO2 is quenched very efficiently via the addition of 1 equiv of Cu(2+). Addition of pyrophosphate (PPi) into the weakly fluorescent solution of PPECO2 and Cu(2+) induces recovery of the polymer's fluorescence; the recovery occurs because PPi complexes with Cu(2+), effectively sequestering the ion so it cannot bind to the carboxylate groups of the polymer. A calibration curve was developed that relates the extent of fluorescence recovery to [PPi], making the PPECO2-Cu(2+) system a sensitive and selective turn-on sensor for PPi. Using the PPECO2-Cu(2+) system as the signal transducer, a real-time fluorescence turn-off assay for the enzyme alkaline phosphatase (ALP) using PPi as the substrate is developed. The assay operates with [PPi] in the micromolar range, and it offers a straightforward and rapid detection of ALP activity with the enzyme present in the nanomolar concentration range, operating either in an end point or real-time format. Kinetic and product inhibition parameters are derived by converting time-dependent fluorescence intensity into PPi (substrate) concentration, thus allowing calculation of the initial reaction rates (v(o)). Weak, nonspecific fluorescence responses are observed concomitant to addition of other proteins to the assay solution; however, the signal response to ALP is demonstrated to arise from the ALP catalyzed hydrolysis of PPi to phosphate (Pi). PMID:18855416

Liu, Yan; Schanze, Kirk S

2008-11-15

435

Reaction kinetics of cellulose hydrolysis in subcritical and supercritical water  

NASA Astrophysics Data System (ADS)

The uncertainties in the continuous supply of fossil fuels from the crisis-ridden oil-rich region of the world is fast shifting focus on the need to utilize cellulosic biomass and develop more efficient technologies for its conversion to fuels and chemicals. One such technology is the rapid degradation of cellulose in supercritical water without the need for an enzyme or inorganic catalyst such as acid. This project focused on the study of reaction kinetics of cellulose hydrolysis in subcritical and supercritical water. Cellulose reactions at hydrothermal conditions can proceed via the homogeneous route involving dissolution and hydrolysis or the heterogeneous path of surface hydrolysis. The work is divided into three main parts. First, the detailed kinetic analysis of cellulose reactions in micro- and tubular reactors was conducted. Reaction kinetics models were applied, and kinetics parameters at both subcritical and supercritical conditions were evaluated. The second major task was the evaluation of yields of water soluble hydrolysates obtained from the hydrolysis of cellulose and starch in hydrothermal reactors. Lastly, changes in molecular weight distribution due to hydrothermolytic degradation of cellulose were investigated. These changes were also simulated based on different modes of scission, and the pattern generated from simulation was compared with the distribution pattern from experiments. For a better understanding of the reaction kinetics of cellulose in subcritical and supercritical water, a series of reactions was conducted in the microreactor. Hydrolysis of cellulose was performed at subcritical temperatures ranging from 270 to 340 °C (tau = 0.40--0.88 s). For the dissolution of cellulose, the reaction was conducted at supercritical temperatures ranging from 375 to 395 °C (tau = 0.27--0.44 s). The operating pressure for the reactions at both subcritical and supercritical conditions was 5000 psig. The results show that the rate-limiting step in converting cellulose to fermentable sugars in subcritical and supercritical water differs because of the difference in their activation energies. Cellulose and starch were both hydrolyzed in micro- and tubular reactors and at subcritical and supercritical conditions. Due to the difficulty involved in generating an aqueous based dissolved cellulose and having it reacted in subcritical water, dissolved starch was used instead. Better yield of water soluble hydrolysates, especially fermentable sugars, were observed from the hydrolysis of cellulose and dissolved starch in subcritical water than at supercritical conditions. The concluding phase of this project focuses on establishing the mode of scission of cellulose chains in the hydrothermal reactor. This was achieved by using the simulated degradation pattern generated based on different scission modes to fingerprint the degradation pattern obtained from experiment.

Olanrewaju, Kazeem Bode

436

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.

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

437

Metal ion-promoted hydrolysis of the antioxidant cardioprotective agent dexrazoxane (ICRF-187) and its one-ring open hydrolysis products to its metal-chelating active form  

Microsoft Academic Search

The metal ion-promoted hydrolysis of the doxorubicin cardioprotective agent dexrazoxane (ICRF-187) has been studied by HPLC and spectrophotometrically. Dexrazoxane is thought to be cardioprotective through the ability of its rings-opened hydrolysis product (D) to chelate loosely bound iron, thus preventing iron-based oxygen free radical damage. While neither Mg(II) nor Ca(II) promoted the hydrolysis of the opening of the first dexrazoxane

Joan L. Buss; Brian B. Hasinoff

1997-01-01

438

Complete and efficient enzymic hydrolysis of pretreated wheat straw  

Microsoft Academic Search

A fractionation of wheat straw components in a two-step chemical pretreatment is proposed. Hemicelluloses were hydrolysed by dilute sulphuric acid, allowing a substantial recovery of crystalline xylose. Lignin was removed by means of a mild alkaline\\/oxidative solubilisation procedure, involving no sulphite or chlorine and its derivatives. The use of diluted reagents and relatively low temperatures, was both cheap and environmentally

Nicoletta Curreli; Mario Agelli; Brunella Pisu; Antonio Rescigno; Enrico Sanjust; Augusto Rinaldi

2002-01-01

439

Inhibition of alkaline phosphatase activity by glucose.  

PubMed

Non-enzymatic glycosylation (NEG) of alkaline phosphatase (AP) was studied after short- and long-term incubation with glucose and other carbohydrates. Glucose and amino sugars clearly inhibited the enzyme activity; this was in contrast to reducing and non-reducing disaccharides, which had an enhancing effect. After AP had been incubated with 18 nmol/l glucose for 180 minutes (short-term incubation), a subsequent extensive dialysis revealed full recovery of the enzymatic activity. This, plus the demonstration of a [3H]sodium borohydride-reducible glucose-protein adduct, indicated that initially a labile aldimine (Schiff base) had been formed. Binding experiments with [14C]glucose and failure of dialysis to achieve a recovery of enzymatic activity after long-term incubation suggested that subsequently a stable ketoamine product had been formed. This was further confirmed by the thiobarbituric acid test, which revealed 0.65 nmol 5-hydroxymethylfurfural/mg protein for glycosylated AP compared to 0.11 for the non-glycosylated control. Preliminary results further suggest that NEG of AP also occurs in vivo. Streptozotocin diabetic rats had significantly lower serum AP activities than did non-diabetic controls (mean +/- SD: 153.7 +/- 28.4 vs. 760.5 +/- 95.7 U/l; p less than 0.001). Blood glucose levels and serum AP activity, which had been determined simultaneously during an oral glucose tolerance test, showed without exception an inverse relationship in each of 32 healthy children studied. The biological significance of these findings remains to be established. PMID:6627674

Pollak, A; Coradello, H; Leban, J; Maxa, E; Sternberg, M; Widhalm, K; Lubec, G

1983-09-15

440

Research on Separators for Alkaline Zinc Batteries. Final Report.  

National Technical Information Service (NTIS)

This project is concerned with the research and development of a hybrid separator as an improved battery separator in alkaline zinc secondary batteries. Particular emphasis has been directed toward increasing the cycle life of zinc electrodes by controlli...

R. S. Yeo

1985-01-01