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201.
Yifan Deng Bruno Faivre Dr. Olivier Back Dr. Murielle Lombard Dr. Ludovic Pecqueur Prof. Dr. Marc Fontecave 《Chembiochem : a European journal of chemical biology》2020,21(1-2):163-170
The hydroxylation of phenols into polyphenols, which are valuable chemicals and pharmaceutical products, is a challenging reaction. The search for green synthetic processes has led to considering microorganisms and pure hydroxylases as catalysts for phenol hydroxylation. Herein, we report the structural and functional characterization of the flavin adenine dinucleotide (FAD)-dependent 4-hydroxyphenylacetate 3-monooxygenase from Escherichia coli, named HpaB. It is shown that this enzyme enjoys a relatively broad substrate specificity, which allows the conversion of a number of non-natural phenolic compounds, such as tyrosol, hydroxymandelic acid, coumaric acid, hydroxybenzoic acid and its methyl ester, and phenol, into the corresponding catechols. The reaction can be performed by using a simple chemical assay based on formate as the electron donor and the organometallic complex [Rh(bpy)Cp*(H2O)]2+ (Cp*: 1,2,3,4,5-pentamethylcyclopentadiene, bpy: 2,2′-bipyridyl) as the catalyst for FAD reduction. The availability of a crystal structure of HpaB in complex with FAD at 1.8 Å resolution opens up the possibility of the rational tuning of the substrate specificity and activity of this interesting class of phenol hydroxylases. 相似文献
202.
Jana A. Hirsch Geoffrey F. Green Marc Peterson Daniel A. Rodriguez Penny Gordon-Larsen 《Journal of Urbanism》2017,10(2):181-197
While increasing evidence suggests an association between physical infrastructure in neighborhoods and health outcomes, relatively little research examines how neighborhoods change physically over time and how these physical improvements are spatially distributed across populations. This paper describes the change over 25 years (1985–2010) in bicycle lanes, off-road trails, bus transit service and parks, and spatial clusters of changes in these domains relative to neighborhood sociodemographics in four US cities that are diverse in terms of geography, size, and population. Across all four cities we identified increases in bicycle lanes, off-road trails, and bus transit service, with spatial clustering in these changes that related to neighborhood sociodemographics. Overall, we found evidence of positive changes in physical infrastructure commonly identified as supportive of physical activity. However, the patterning of infrastructure change by sociodemographic change encourages attention to the equity in infrastructure improvements across neighborhoods. 相似文献
203.
Alan L. Chaffee Galinda Lay Marc Marshall W. Roy Jackson Yi Fei T. Vincent Verheyen Steven G. Scott 《Fuel》2010,89(11):3241-3249
The structure of a suite of high-volatile, bituminous Surat Basin, Queensland coals has been investigated by a combination of analytical probes. These included elemental analyses, pyrolysis-gas chromatography-mass spectroscopy and Fourier transform infrared spectroscopy, together with a study of their liquefaction products in both tetralin and solvent free-tin catalysed hydrogenations. Samples were gathered across a 300 m depth interval intersected by the sampling well. Most techniques revealed clear but subtle differences in structure as a function of depth. The oils produced by solvent free-tin catalysed hydrogenation, however, showed very distinct dependence with depth and the waxy content, as indicated by 1H-NMR, could be correlated with the coal seam gas content. 相似文献
204.
Marc Flinders Darin Ray Angela Anderson Raymond A. Cutler 《Journal of the American Ceramic Society》2005,88(8):2217-2226
Silicon carbide, with single-edge precracked beam (SEPB) toughness greater than 7 MPa·m1/2 , was made by hot-pressing using Al–B–C (ABC) or Al–Y2 O3 (YAG) as additives. The hardness of SiC processed with a liquid phase was always less than SiC densified without a liquid phase despite having a similar or finer grain size. With increasing Al content, the ABC system changed from trans- to intergranular fracture with a drop in hardness and a two- to threefold increase in SEPB toughness. Strength and Weibull modulus for materials processed with a liquid phase were higher than those of solid-state densified SiC. Ballistic testing, however, did not show any improvement over SiC densified with B and C additives. Depth of penetration was controlled by hardness of the SiC-based materials, while V 50 values for 14.5 mm WC–Co cored projectiles were in the range of 720–750 m/s for all materials tested. 相似文献
205.
Abdelkader Kahouli Olivier Gallot‐Lavallée Pacal Rain Olivier Lesaint Christophe Guillermin Jean‐Marc Lupin 《应用聚合物科学杂志》2015,132(28)
The dielectric properties of two grades of bi‐oriented isotactic polypropylene were studied with a variety of techniques: breakdown field measurements, dielectric spectroscopy, thermally stimulated depolarization currents (Is), and direct‐current (dc) conduction I values. Standard polypropylene (STPP) and high‐crystallinity polypropylene (HCPP) films were investigated. Measurements were carried out over a wide temperature range (?150°C/+125°C). The breakdown fields in both materials showed a very small difference. On the other hand, the dielectric losses and dc conduction I values were significantly lower in HCPP. Both materials showed a decrease in the dielectric loss versus temperature in the range 20–90°C; this is favorable for application in alternating‐current power capacitors. The analysis of the dc I value allowed us to find evidence of two main conduction mechanisms: (1) below 80°C in both materials, a hopping mechanism due to the motion of electrons occurred in the amorphous phase, and (2) above 80°C, ionic conduction occurred in HCPP, and hopping conduction occurred in STPP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42224. 相似文献
206.
Novel Tacrine‐Grafted Ugi Adducts as Multipotent Anti‐Alzheimer Drugs: A Synthetic Renewal in Tacrine–Ferulic Acid Hybrids 下载免费PDF全文
Mohamed Benchekroun Dr. Manuela Bartolini Dr. Javier Egea Dr. Alejandro Romero Dr. Elena Soriano Dr. Marc Pudlo Vincent Luzet Prof. Vincenza Andrisano Dr. María‐Luisa Jimeno Dr. Manuela G. López Sarah Wehle Prof. Tijani Gharbi Prof. Bernard Refouvelet Lucía de Andrés Clara Herrera‐Arozamena Prof. Barbara Monti Prof. Maria Laura Bolognesi Prof. María Isabel Rodríguez‐Franco Prof. Dr. Michael Decker Prof. José Marco‐Contelles Dr. Lhassane Ismaili 《ChemMedChem》2015,10(3):523-539
Herein we describe the design, multicomponent synthesis, and biological, molecular modeling and ADMET studies, as well as in vitro PAMPA‐blood–brain barrier (BBB) analysis of new tacrine–ferulic acid hybrids (TFAHs). We identified (E)‐3‐(hydroxy‐3‐methoxyphenyl)‐N‐{8[(7‐methoxy‐1,2,3,4‐tetrahydroacridin‐9‐yl)amino]octyl}‐N‐[2‐(naphthalen‐2‐ylamino)2‐oxoethyl]acrylamide (TFAH 10 n ) as a particularly interesting multipotent compound that shows moderate and completely selective inhibition of human butyrylcholinesterase (IC50=68.2 nM ), strong antioxidant activity (4.29 equiv trolox in an oxygen radical absorbance capacity (ORAC) assay), and good β‐amyloid (Aβ) anti‐aggregation properties (65.6 % at 1:1 ratio); moreover, it is able to permeate central nervous system (CNS) tissues, as determined by PAMPA‐BBB assay. Notably, even when tested at very high concentrations, TFAH 10 n easily surpasses the other TFAHs in hepatotoxicity profiling (59.4 % cell viability at 1000 μM ), affording good neuroprotection against toxic insults such as Aβ1–40, Aβ1–42, H2O2, and oligomycin A/rotenone on SH‐SY5Y cells, at 1 μM . The results reported herein support the development of new multipotent TFAH derivatives as potential drugs for the treatment of Alzheimer′s disease. 相似文献
207.
We show that enriching logit mode choice model specification by mode attributes, socio economic variables and trip purpose
characteristics significantly improves model quality, and that Box-Cox transformations applied to model attributes imply an
asymmetry of the reaction curve, as well as more reasonable properties (diminishing marginal values of time savings, elasticities
and values of time that differ among the modes) than those of the linear logit model. Moreover, the model yielded very different
high speed rail market shares for Germany than results obtained with the usual linear utility functions.
Received: December 1996 / Accepted: April 1997 相似文献
208.
Marc Gravel Laszlo Kiss Jean-Marc Martel Wilson L. Price 《International Transactions in Operational Research》1994,1(3):363-373
This paper presents a decision support system designed to aid the production planner in choosing the values of the principle parameters governing just-in-time manufacturing. The DSS uses a knowledge base composed of data from simulations of the production of the entire product line under systematically varied conditions. The planners may add data from actual production experience as it is obtained. The stochastic dominance outranking method of Martel and Zaras allows the identification of clusters of parameters that respect the preferences of the decision maker. When launching an order for a product, the decision maker may judge certain sets of parameters to be equivalent. A visual interactive simulation model will then allow their comparison according to three performance criteria. 相似文献
209.
Chandolia RK Luetjens CM Wistuba J Yeung CH Nieschlag E Simoni M 《Reproduction (Cambridge, England)》2006,132(2):355-363
Data on pubertal maturation in male marmoset, a model for human reproduction, are scant and conflicting. We collected data on novel parameters to characterize puberty. Twenty-five marmoset monkeys were assigned to five age groups by weeks (wk): 21 (pre-pubertal), 43 (onset of puberty), 52 (fully pubertal), 70 (mature), and 116 (fully adult). Serum and intratesticular testosterone and pituitary bioactive chorionic gonadotropin (bioCG) were measured. Testicular development was assessed by ultrasonography, histology, and flow cytometry. Three consecutive blood samples revealed extreme fluctuations in testosterone concentrations, suggesting an erratic secretion. Age-related changes in serum testosterone and pituitary bioCG concentrations were observed. Intratesticular androgens (ITAs) showed high fluctuations within groups at all ages and were high in some animals by 21 wk. Unexpectedly, no correlation between pituitary bioCG and serum testosterone or ITAs was found, but these parameters significantly correlated with testicular weight and volume. These observations were consistent a dependence on the testis growth on bioCG. Unfortunately, the low serum levels of bioCG were not measurable in this study. At 43 wk, the animals reached puberty. At 52 wk of age, animals attained maximum body and epididymal weights and qualitatively normal spermatogenesis, but testes continued growing, reaching a maximum of all parameters at 70 wk of age, without further major changes at the age of 116 wk. It is concluded that (1) gonadal activation is evident at wk 21, (2) the male marmoset reaches the pubertal threshold around 43 wk of age, attains qualitative parameters at 52 wk, matures further to sexual maturity at 70 wk, and (3) serum testosterone and ITAs are highly variable without any identifiable correlation with pituitary bioCG. 相似文献
210.
Effect of starvation on the performance and re-acclimation of biotrickling filters for air pollution control 总被引:2,自引:0,他引:2
Biotrickling filters for air pollution control are expected to encounter fluctuating conditions or periods without pollutant supply. In the present study, we investigated the effect of pollutant starvation in bench-scale biotrickling filters treating toluene. The experimental protocol consisted of starving biotrickling filters under various conditions: with or without airflow, with or without liquid recycle, and with or without an alternate carbon source (glucose) supply. The duration of the period without toluene was varied from 2 to 9 days, during time which the biotrickling filters were monitored for biomass content, endogenous and toluene-induced oxygen uptake rates during starvation, and toluene overall elimination capacity after restart. During starvation, all reactors lost their ability to degrade toluene within 5 days, regardless of the mode of starvation. The biomass content significantly decreased during starvation, in particular in those reactors where the recycle liquid was maintained, but this decrease was not critical for future re-acclimation. Glucose addition to starved biotrickling filters had several detrimental effects. It resulted in a faster decrease of the biomass content and slowed the reacclimation phase. Overall, the results show that the reacclimation of toluene-degrading biotrickling filters after periods of nonuse is short (10-24 h to re-establish full performance), and they suggest that, in the case of toluene-degrading biotrickling filters, re-acclimation time is largely governed by the induction of key pollutant-degrading enzymes. 相似文献