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101.
Aleena Francis Valookaran Jenny Bouchard Basma Milad Aloud Sijo Joseph Thandapilly Thomas Netticadan 《Molecules (Basel, Switzerland)》2022,27(21)
Hypertension is a common risk factor for cardiovascular disease and mortality worldwide. Proper nutrition and diet are known to play an indispensable role in the treatment and management of hypertension. Bioactive compounds that occur in small quantities in foods such as onions, fish and red wine are being intensively studied to uncover their vasoprotective, antioxidant, anti-proliferative and anti-inflammatory effects which are beneficial to attenuate chronic disease and protect human health. In this article, the anti-hypertensive, and cardio-protective effects of five food-derived bioactive compounds: resveratrol, quercetin, coenzyme Q10, DHA and EPA and their proposed mechanisms of action are reviewed in detail. 相似文献
102.
Genetic engineering in Streptomyces roseosporus to produce hybrid lipopeptide antibiotics 总被引:5,自引:0,他引:5
Miao V Coëffet-Le Gal MF Nguyen K Brian P Penn J Whiting A Steele J Kau D Martin S Ford R Gibson T Bouchard M Wrigley SK Baltz RH 《Chemistry & biology》2006,13(3):269-276
Daptomycin is a lipopeptide antibiotic produced by a nonribosomal peptide synthetase (NRPS) in Streptomyces roseosporus. The holoenzyme is composed of three subunits, encoded by the dptA, dptBC, and dptD genes, each responsible for incorporating particular amino acids into the peptide. We introduced expression plasmids carrying dptD or NRPS genes encoding subunits from two related lipopeptide biosynthetic pathways into a daptomycin nonproducing strain of S. roseosporus harboring a deletion of dptD. All constructs successfully complemented the deletion in trans, generating three peptide cores related to daptomycin. When these were coupled with incomplete methylation of 1 amino acid and natural variation in the lipid side chain, 18 lipopeptides were generated. Substantial amounts of nine of these compounds were readily obtained by fermentation, and all displayed antibacterial activity against gram-positive pathogens. 相似文献
103.
UVB effects on the photosystem II-D1 protein of phytoplankton and natural phytoplankton communities 总被引:1,自引:0,他引:1
The reaction center of photosystem II is susceptible to photodamage. In particular the D1 protein located in the photosystem II core has a rapid, light-dependent turnover termed the photosystem II repair cycle that, under illumination, degrades and resynthesizes D1 protein to limit accumulation of photodamaged photosystem II. Most studies concerning the effects of UVB (280-320 nm) on this cycle have been on cyanobacteria or specific phytoplankton species rather than on natural communities of phytoplankton. During a 5-year multidisciplinary project on the effects of UV radiation (200-400 nm) on natural systems, the effects of UVB on the D1 protein of natural phytoplankton communities were assessed. This review provides an overview of photoinhibitory effects of light on cultured and natural phytoplankton, with an emphasis on the interrelation of UVB exposure, D1 protein degradation and the repair of photosystem II through D1 resynthesis. Although the UVB component of the solar spectrum contributes to the primary photoinactivation of photosystem II, we conclude that, in natural communities, inhibition of the rate of the photosystem II repair cycle is a more important influence of UVB on primary productivity. Indeed, exposing tropical and temperate phytoplankton communities to supplemented UVB had more inhibitory effect on D1 synthesis than on the D1 degradation process itself. However, the rate of net D1 damage was faster for the tropical communities, likely because of the effects of high ambient light and water temperature on mechanisms of protein degradation and synthesis. 相似文献
104.
We study a discrete-time approximation for solutions of systems of decoupled Forward–Backward Stochastic Differential Equations (FBSDEs) with jumps. Assuming that the coefficients are Lipschitz-continuous, we prove the convergence of the scheme when the number of time steps n goes to infinity. The rate of convergence is at least n−1/2+ε, for any ε>0. When the jump coefficient of the first variation process of the forward component satisfies a non-degeneracy condition which ensures its inversibility, we achieve the optimal convergence rate n−1/2. The proof is based on a generalization of a remarkable result on the path-regularity of the solution of the backward equation derived by Zhang [J. Zhang, A numerical scheme for BSDEs, Annals of Applied Probability 14 (1) (2004) 459–488] in the no-jump case. 相似文献
105.
Bouchard M Smith DC Carabatos-Nédelec C 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(4):1101-1113
Raman microscopy (RM) is widely used in archaeometrical studies of pigments, geomaterials and biomaterials in the Cultural Heritage, but one domain has received relatively less attention: the colouring of stained glass. This feasibility study investigates the advantages and disadvantages of employing RM alone in this field by means of a study of modern commercial glasses, modern commercial pigments, and a few archaeological stained glasses, but especially by an experimental project whereby the authors created stained glass. The different kinds of possible unreacted or reacted material are rigorously established. The distinction between Na, K, Ca glasses was explored, as well as the red colouring of an industrial glass which was proved to be due to the presence of (Zn, Cd)S(x)Se(1-x). Yellow, green, blue and maroon pigments were studied before and after an initial firing and then after heating on glass. The quality of the Raman spectra varied enormously and was sometimes disappointing. Nevertheless RM successfully identified various coloured products such as bindheimite, crocoite, cobalt aluminate, haematite; relict reactants such as corundum, eskolaite and oxides of Co or Pb; and provided indications of other phases such as maghemite or Co-olivine. One conclusion is that the amount of chemical reaction between the pigments and the glass is small compared to the amount in between the pigments. Comments are made on the potential for dating archaeological glass from the known age of synthesis of the pigments, and of the dangers of this approach. Overall it has been shown that RM can be useful for studying stained glass, especially for remote in situ analytical operations with mobile RM, but one must expect some problems either with fluorescence or weak spectra. 相似文献
106.
Given a graph G=(V,E) with strictly positive integer weights ωi on the vertices iV, a k-interval coloring of G is a function I that assigns an interval I(i){1,…,k} of ωi consecutive integers (called colors) to each vertex iV. If two adjacent vertices x and y have common colors, i.e. I(i)∩I(j)≠0/ for an edge [i,j] in G, then the edge [i,j] is said conflicting. A k-interval coloring without conflicting edges is said legal. The interval coloring problem (ICP) is to determine the smallest integer k, called interval chromatic number of G and denoted χint(G), such that there exists a legal k-interval coloring of G. For a fixed integer k, the k-interval graph coloring problem (k-ICP) is to determine a k-interval coloring of G with a minimum number of conflicting edges. The ICP and k-ICP generalize classical vertex coloring problems where a single color has to be assigned to each vertex (i.e., ωi=1 for all vertices iV).Two k-interval colorings I1 and I2 are said equivalent if there is a permutation π of the integers 1,…,k such that ℓI1(i) if and only if π(ℓ)I2(i) for all vertices iV. As for classical vertex coloring, the efficiency of algorithms that solve the ICP or the k-ICP can be increased by avoiding considering equivalent k-interval colorings, assuming that they can be identified very quickly. To this purpose, we define and prove a necessary and sufficient condition for the equivalence of two k-interval colorings. We then show how a simple tabu search algorithm for the k-ICP can possibly be improved by forbidding the visit of equivalent solutions. 相似文献
107.
In principle, liabilities combining both insurancial risks (e.g. mortality/longevity, crop yield,...) and pure financial risks
cannot be priced neither by applying the usual actuarial principles of diversification, nor by arbitrage-free replication
arguments. Still, it has been often proposed in the literature to combine these two approaches by suggesting to hedge a pure
financial payoff computed by taking the mean under the historical/objective probability measure on the part of the risk that
can be diversified. Not surprisingly, simple examples show that this approach is typically inconsistent for risk adverse agents.
We show that it can nevertheless be recovered asymptotically if we consider a sequence of agents whose absolute risk aversions
go to zero and if the number of sold claims goes to infinity simultaneously. This follows from a general convergence result
on utility indifference prices which is valid for both complete and incomplete financial markets. In particular, if the underlying
financial market is complete, the limit price corresponds to the hedging cost of the mean payoff. If the financial market
is incomplete but the agents behave asymptotically as exponential utility maximizers with vanishing risk aversion, we show
that the utility indifference price converges to the expectation of the discounted payoff under the minimal entropy martingale
measure. 相似文献
108.
R.D. Shannon J.L. Gillson R.J. Bouchard 《Journal of Physics and Chemistry of Solids》1977,38(8):877-881
Single crystals of CdSnO3, Cd2SnO4, ln2TeO6 and CdIn2O4 were grown by either flux or high pressure methods. High electrical conductivity resulted from chemical substitution or oxygen deficiency. Crystallographic and conductivity data are given. 相似文献
109.
110.
Shanqiang Wu Christian Bouchard Serge Kaliaguine 《Research on Chemical Intermediates》1998,24(3):273-289
In this study, a catalytic membrane reactor was developed. A titanium silicalite (TS-1) containing polydimethylsiloxane (PDMS)
catalytic composite membrane was placed at the interface between the two immiscible phases containing respectively n-hexane
(organic phase) and a solution of hydrogen peroxide (aqueous phase). This allowed adequate transport of both reactants to
the catalyst surface, without using a co-solvent. This concept of zeolite containing catalytic membrane as interphase contactor,
which may be applicable to numerous multiphase reactions, has been tested for the oxyfunctionalization of n-hexane to a mixture
of hexanols and hexanones using H2O2 as the oxidant. It was shown that the oxyfunctionalization products are formed in and separated by the catalytic membrane.
The experimental results illustrated the technical advantages of such a catalytic membrane reactor since the observed conversion
and selectivity are similar to the ones obtained with the same catalyst in a conventional reactor. The various factors (membrane
thickness, catalyst loading and membrane modifications) which may affect the membrane catalytic and permeation performances
were investigated. 相似文献