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181.
Lessening polygalacturonase activity in a commercial enzyme preparation by exposure to pulsed electric fields 总被引:1,自引:0,他引:1
Joaquín?Giner Vicente?Gimeno Montserrat?Palomes Gustavo?V.?Barbosa-Cánovas Olga?MartínEmail author 《European Food Research and Technology》2003,217(1):43-48
The effect of high-intensity pulsed electric field (HIPEF) treatments on polygalacturonase (PG) activity in an aqueous solution of a commercial enzyme preparation was evaluated. HIPEF treatments reduced PG activity notably. Exponentially decaying pulses of 40 and 160 µs generated by a laboratory scale device were applied in a batch processing and bipolar mode. Electric fields ranged from 5.18 to 19.39 kV/cm. The number of pulses ranged up to 400. Temperature was always below 25 °C. Maximum inactivation of PG activity (98%) required 32.4 ms HIPEF treatment at 10.28 kV/cm. PG activity depleted exponentially because of HIPEF treatments. The first order rate constants ranged from 32 to 590 µs -1 and increased exponentially with electric field intensity. PG activity decreased exponentially with input electric energy density. 相似文献
182.
Evidence for fumonisin inhibition of ceramide synthase in humans consuming maize‐based foods and living in high exposure communities in Guatemala
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183.
Dietary rapeseed/canola‐oil supplementation reduces serum lipids and liver enzymes and alters postprandial inflammatory responses in adipose tissue compared to olive‐oil supplementation in obese men
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184.
Leong SL Pettersson OV Rice T Hocking AD Schnürer J 《International journal of food microbiology》2011,145(1):57-63
Little is known about the mould, Xeromyces bisporus, unique in its strong xerophilicity and ability to grow at water activity (aw) 0.62, lower than for any other known organism. The linear growth rates of one fast and one slow-growing strain of X. bisporus were assessed at 20, 25, 30 and 37 °C on solid agar media containing a mixture of glucose and fructose to reduce aw to 0.94, 0.88, 0.84, 0.80, 0.76 and 0.66. Growth rates of xerophilic species closely related to X. bisporus, viz. Chrysosporium inops, C. xerophilum and Monascus eremophilus, were also assessed. Optimal conditions for growth of both X. bisporus strains were approx. 0.84 aw and 30 °C, despite FRR 2347 growing two- to five-fold faster than CBS 185.75. X. bisporus FRR 2347 even grew well at 0.66 aw (0.48 mm/day). C. inops and C. xerophilum were more tolerant of high aw than X. bisporus, and could be differentiated from each other based on: the faster growth of C. xerophilum; its preference for temperatures ≥ 30 °C and aw ≥ 0.94 (c.f. ≤ 25 °C and ~ 0.88 aw for C. inops); and its ability to grow at 0.66 aw, which is the lowest aw reported to date for this species. M. eremophilus grew slowly (max. 0.4 mm/day) even in its optimal conditions of ~ 0.88 aw and 25 °C. To investigate the competitive characteristics of X. bisporus at low aw, both X. bisporus strains were grown in dual-culture with xerotolerant species Aspergillus flavus and Penicillium roqueforti, and xerophilic species A. penicillioides, C. inops, C. xerophilum and Eurotium chevalieri, on glucose-fructose agar plates at 0.94, 0.84, 0.80 and 0.76 aw and at 25 °C. Growth rates and types of interactions were assessed. Excretion of inhibitory substances acting over a long-range was not observed by any species; inhibitors acting over a short-range that temporarily slowed competitors' growth or produced a protective zone around the colony were occasionally observed for A. penicillioides, C. inops and C. xerophilum. Instead, rapid growth relative to the competitor was the most common means of dominance. The xerotolerant species, A. flavus and P. roqueforti were dominant over X. bisporus at 0.94 aw. E. chevalieri was often dominant due to its rapid growth over the entire aw range. At aw < 0.80, X. bisporus was competitive because it grew faster than the other species examined. This supports the concept that its ideal environmental niche is sugary foods with low aw. 相似文献
185.
Michael Reinwarth Bernhard Glotzbach Michael Tomaszowski Sebastian Fabritz Dr. Olga Avrutina Prof. Dr. Harald Kolmar 《Chembiochem : a European journal of chemical biology》2013,14(1):137-146
Bioactive peptides often contain several disulfide bonds that provide the main contribution to conformational rigidity and structural, thermal, or biological stability. Among them, cystine‐knot peptides—commonly named “knottins”—make up a subclass with several thousand natural members. Hence, they are considered promising frameworks for peptide‐based pharmaceuticals. Although cystine‐knot peptides are available through chemical and recombinant synthetic routes, oxidative folding to afford the bioactive isomers still remains a crucial step. We therefore investigated the oxidative folding of ten protease‐inhibiting peptides from two knottin families, as well as that of an HIV entry inhibitor and of aprotinin, under two conventional sets of folding conditions and by a newly developed procedure. Kinetic studies identified folding conditions that resulted in correctly folded miniproteins with high rates of conversion even for highly hydrophobic and aggregation‐prone peptides in concentrated solutions. 相似文献
186.
Tcherkasskaya Olga; Ptitsyn Oleg B. 《Protein engineering, design & selection : PEDS》1999,12(6):485-490
The direct energy transfer technique was modified and appliedto probe the relative localization of apomyoglobin A-, G- andH-helixes, which are partly protected from deuterium exchangein the equilibrium molten globule state and in the molten globule-likekinetic intermediate. The non-radiative transfer of tryptophanelectronic energy to 3-nitrotyrosine was studied in differentconformational states of apomyoglobin (native, molten globule,unfolded) and interpreted in terms of average distances betweengroups of the protein chain. The experimental data show thatthe distance between the middle of A-helix and the N-terminusof G-helix as well as the distance between the middle of theA-helix and the C-terminus of the H-helix in the molten globulestate are close to those in the native state. This is a strongargument in favor of similarity of the overall architectureof the molten globule and native states. 相似文献
187.
Longitudinal stability of temperamental exuberance and social–emotional outcomes in early childhood.
Degnan Kathryn A.; Hane Amie Ashley; Henderson Heather A.; Moas Olga Lydia; Reeb-Sutherland Bethany C.; Fox Nathan A. 《Canadian Metallurgical Quarterly》2011,47(3):765
The goals of the current study were to investigate the stability of temperamental exuberance across infancy and toddlerhood and to examine the associations between exuberance and social–emotional outcomes in early childhood. The sample consisted of 291 4-month-olds followed at 9, 24, and 36 months and again at 5 years of age. Behavioral measures of exuberance were collected at 9, 24, and 36 months. At 36 months, frontal electroencephalogram (EEG) asymmetry was assessed. At 5 years, maternal reports of temperament and behavior problems were collected, as were observational measures of social behavior during an interaction with an unfamiliar peer in the laboratory. Latent profile analysis revealed a high, stable exuberance profile that was associated with greater ratings of 5-year externalizing behavior and surgency, as well as observed disruptive behavior and social competence with unfamiliar peers. These associations were particularly true for children who displayed left frontal EEG asymmetry. Multiple factors supported an approach bias for exuberant temperament but did not differentiate between adaptive and maladaptive social–emotional outcomes at 5 years of age. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
188.
A new approach for the characterization of the pore structure of dual porosity rocks 总被引:1,自引:0,他引:1
Christos D. Tsakiroglou Marios A. Ioannidis Olga Vizika 《Chemical engineering science》2009,64(5):847-3709
For the realistic representation of the pore space of dual porosity rocks, a new method of pore structure characterization is developed by combining experimental Hg intrusion/retraction curves with back-scattered scanning electron microscope (BSEM) images and inverse modeling algorithms. The pore space autocorrelation function measured by processing the digitized BSEM images is combined with the surface fractal dimension estimated from the high pressure Hg intrusion (MIP) data to derive a synthetic small-angle neutron scattering (SANS) intensity function, the inversion of which provides a volume-based pore body radius distribution (PBRD). The volume-based PBRD is fitted with a multimodal number-based PBRD consisting of two component distributions: one representing the macroporosity and another one representing the microporosity. Based on arguments of percolation theory, analytical mathematical models are developed to describe the Hg intrusion in and retraction from dual pore networks in terms of the complete PBRD, pore throat radius distribution (PTRD) of macroporosity, drainage accessibility functions (DAFs) of both porosities, and imbibition accessibility functions (IAFs) of both porosities. Inverse modeling of the Hg intrusion data set enables us to estimate the PTRD and DAFs. Inverse modeling of the Hg retraction datasets enables us to estimate a set of primary and secondary IAFs. The method is demonstrated by the pore structure characterization of four outcrop samples of carbonate and sandstone rocks. Analytic approximate equations developed from the critical path analysis (CPA) of percolation theory enable us to calculate explicitly the absolute permeability and the formation factor of the porous rocks using the estimated parameters (PBRD, PTRD, DAF) of the macroporosity. The measured permeability of cores is predicted satisfactorily and observed discrepancies may be attributed to large length-scale macro-heterogeneities which are not evident in BSEM images and Hg porosimetry data. 相似文献
189.
Olga Smith 《Photographies》2018,11(2-3):235-250
This article analyses recent photographic practices that make visible underlying realities faced by Western societies today as they struggle to reconcile contradictions between their policies on race, immigration and ethnicity and the quest for an integrated national identity. The main case studies are drawn from the works of Mohamed Bourouissa and Tobias Zielony. The article demonstrates how their photographic projects confront the logic of social and cultural marginalisation of the immigrant communities, which often overlaps with their spatial consignment to urban peripheries. By combining reality and fiction, symbolism and documentation, these projects offer alternatives to the modes of representation available in photojournalism, as well as re-connecting with the genre of street photography. 相似文献
190.
The aim of this paper is to study the occupational segregation of immigrants in Spain. It analyzes whether age, educational level, gender, region of origin, and years of residence in Spain affect the distribution of immigrants across occupations. In addition, given the remarkable increase of immigrants in the last few years and the adjustments that have occurred in the Spanish labor market from the current economic crisis, the evolution of the occupational segregation of immigrants between 1996 and 2009 is addressed. For these purposes, several measures recently proposed in the literature are used. 相似文献