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41.
Novel hybrid SiO2‐coated CdTe quantum dots (QDs) were created using CdTe QDs coated with a hybrid SiO2 shell containing Cd2+ ions and a sulfur source via a sol–gel process in aqueous solution. Aqueous CdTe QDs with tunable emitting color created through a reaction between cadmium chloride and sodium hydrogen telluride was used as cores for the preparation of hybrid SiO2‐coated CdTe QDs. In our experiments we found that the surface state of the cores and preparation conditions that affect the formation of the hybrid SiO2 shell also greatly affect photoluminescence of the hybrid SiO2‐coated CdTe QDs. The generation of CdS‐like clusters in the vicinity of the CdTe QDs, caused the quantum size effect of the QDs to be greatly reduced, which changes photoluminescence properties of the hybrid QDs fundamentally. Namely, the novel hybrid SiO2 shell played an important role in generating a series of specific optical properties. In addition, the novel hybrid SiO2 shell can be created if no CdTe QD is added. In order to gain an insight into the inter structure of the hybrid shell, we characterized the hybrid SiO2‐coated CdTe QDs using X‐ray diffraction analysis and discuss the formation mechanism of such a hybrid structure. This work is significant because the novel hybrid SiO2‐coated CdTe QDs with its excellent properties can be used in many applications, such as biolabeling and optoelectronic devices. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
42.
Bioinformatics tools have facilitated the reconstruction and analysis of cellular metabolism of various organisms based on information encoded in their genomes. Characterization of cellular metabolism is useful to understand the phenotypic capabilities of these organisms. It has been done quantitatively through the analysis of pathway operations. There are several in silico approaches for analyzing metabolic networks, including structural and stoichiometric analysis, metabolic flux analysis, metabolic control analysis, and several kinetic modeling based analyses. They can serve as a virtual laboratory to give insights into basic principles of cellular functions. This article summarizes the progress and advances in software and algorithm development for metabolic network analysis, along with their applications relevant to cellular physiology, and metabolic engineering with an emphasis on microbial strain optimization. Moreover, it provides a detailed comparative analysis of existing approaches under different categories. 相似文献
43.
We benchmark the performance of four treatments of electron exchange and correlation in the prediction of structural and elastic properties of a range of minerals. The treatments used are the Hartree-Fock (HF) theory, the local density approximation (LDA) and the generalised gradient approximation (GGA) to the density functional theory (DFT) and Becke's three parameter hybrid functional (B3LYP). We find that the hybrid functional, B3LYP method yields computed elastic properties in significantly better agreement to experiment than HF or DFT-LDA and performs at least as well, if not better than the most successful DFT-GGA functionals. We suggest that B3LYP is a simple, reliable and computationally efficient tool for the ab initio simulation of mineral systems. 相似文献
44.
《Chronobiology international》2013,30(2):191-192
Most variables of interest in laboratory medicine show predictable changes with several frequencies in the span of time investigated. The waveform of such nonsinusoidal rhythms can be well described by the use of multiple components rhythmometry, a method that allows fitting a linear model with several cosine functions. The method, originally described for analysis of longitudinal time series, is here extended to allow analysis of hybrid data (time series sampled from a group of subjects, each represented by an individual series). Given k individual series, we can fit the same linear model with m different frequencies (harmonics or not from one fundamental period) to each series. This fit will provide estimations for 2m + 1 parameters, namely, the amplitude and acrophase of each component, as well as the rhythm-adjusted mean. Assuming that the set of parameters obtained for each individual is a random sample from a multivariate normal population, the corresponding population parameter estimates can be based on the means of estimates obtained from individuals in the sample. Their confidence intervals depend on the variability among individual parameter estimates. The vari-ance-covariance matrix can then be estimated on the basis of the sample covariances. Confidence intervals for the rhythm-adjusted mean, as well as for the amplitude-acrophase pair, of each component can then be computed using the estimated covariance matrix. The p-values for testing the zero-amplitude assumption for each component, as well as for the global model, can finally be derived using those confidence intervals and the t and F distributions. The method, validated by a simulation study and illustrated by an example of modeling the circadian variation of heart rate, represents a new step in the development of statistical procedures in chronobiology. 相似文献
45.
Scott R. Higgins Ryan J. Lopez Eulyn Pagaling Tao Yan Michael J. Cooney 《Enzyme and microbial technology》2013,52(6-7):344-351
An electrogenic biofilm was developed on a macroporous chitosan-carbon nanotube (CHIT-CNT) electrode under constant poised potential (?0.25 V versus Ag/AgCl reference electrode) and flow through conditions utilizing the effluent of an anaerobic digester as both the inoculant and substrate for the electrogenic biofilm. After 125 days of inoculation the bioelectrode demonstrated an open circuit potential of ?0.62 V and a current density of 9.43 μA cm?3 (at ?0.25 V). Scanning electron microscopy images indicate thorough surface coverage of the biofilm with a high density of bacterial nanowires physically connecting bacteria to bacteria and bacteria to carbon nanotube (electrode surface) suggesting the nanowires are electrically conductive. DGGE was used to identify the major bacterial and archaeal populations. 相似文献
46.
Lila Fishman Angela Stathos Paul M. Beardsley Charles F. Williams Jeffrey P. Hill 《Evolution; international journal of organic evolution》2013,67(9):2547-2560
Chromosomal rearrangements may directly cause hybrid sterility and can facilitate speciation by preserving local adaptation in the face of gene flow. We used comparative linkage mapping with shared gene‐based markers to identify potential chromosomal rearrangements between the sister monkeyflowers Mimulus lewisii and Mimulus cardinalis, which are textbook examples of ecological speciation. We then remapped quantitative trait loci (QTLs) for floral traits and flowering time (premating isolation) and hybrid sterility (postzygotic isolation). We identified three major regions of recombination suppression in the M. lewisii × M. cardinalis hybrid map compared to a relatively collinear Mimulus parishii × M. lewisii map, consistent with a reciprocal translocation and two inversions specific to M. cardinalis. These inferences were supported by targeted intraspecific mapping, which also implied a M. lewisii‐specific reciprocal translocation causing chromosomal pseudo‐linkage in both hybrid mapping populations. Floral QTLs mapped in this study, along with previously mapped adaptive QTLs, were clustered in putatively rearranged regions. All QTLs for male sterility, including two underdominant loci, mapped to regions of recombination suppression. We argue that chromosomal rearrangements may have played an important role in generating and consolidating barriers to gene flow as natural selection drove the dramatic ecological and morphological divergence of these species. 相似文献
47.
Xuan Zhang Jie Zhang Linjiang Tong Yu Luo Mingbo Su Yi Zang Jia Li Wei Lu Yi Chen 《Bioorganic & medicinal chemistry》2013,21(11):3240-3244
A novel class of colchicine-SAHA hybrids were designed and synthesised based on the synergistic antitumor effect of tubulin inhibitors and histone deacetylases (HDAC) inhibitors. To the best of our knowledge, this is the first design of molecules that are dual inhibitors of tubulin and HDAC. Biological evaluations of these compounds included the inhibitory activity of HDAC, in vitro cell cycle analysis in BEL-7402 cells as well as cytotoxicity in five cancer cell lines. 相似文献
48.
Abdessalem Tahiri Fabien Halkett Martine Granier Gwénaelle Gueguen Michel Peterschmitt 《Ecology and evolution》2013,3(8):2619-2633
Bemisia tabaci is a complex of putative species that exhibit a strong geographical pattern. Crossing experiments have revealed various degrees of reproductive isolation between these nascent species, ranging between fertile first‐generation hybrids (F1) and no F1 at all. However, the relevance of these results under natural conditions is generally not known. The worldwide invasion of the putative species Middle East‐Asia Minor 1 (MEAM1) has caused secondary contacts between allopatric species, which in turn provide an opportunity to detect potential hybrids in nature. A total of 346 female B. tabaci were collected in 2003 and 2005 in the North East of Morocco and assigned to MEAM1 (119), Mediterranean (Med) (225) and a new putative species (2) using mitochondrial cytochrome oxidase (mtCOI) gene sequences. MEAM1 and Med individuals were characterized at seven microsatellite loci. MEAM1 and Med were found to be sympatric in 11 of 12 samples (6 fields/year). As previously reported from Spain, MEAM1 frequency decreased over time. The genetic data are consistent with a recent introduction of MEAM1. A Bayesian clustering analysis (Structure ) distinguished two groups, which were 100% consistent with the mtCOI groups. From several lines of evidence, two individuals were identified as hybrids. Assignment profiles using NewHybrids and allele composition indicated that they were not F1 hybrids. The results are discussed in relation to the secondary endosymbiont infection status determined on a sample of individuals, and the contrasting outcomes of the reported crossing experiments between MEAM1 and Med. 相似文献
49.
50.
《Bioorganic & medicinal chemistry》2016,24(4):606-618
The purpose of this study was to synthetize the focused library of 34 new piperazinamides of 3-methyl- and 3,3-dimethyl-(2,5-dioxopyrrolidin-1-yl)propanoic or butanoic acids as potential new hybrid anticonvulsants. These hybrid molecules join the chemical fragments of well-known antiepileptic drugs (AEDs) such as ethosuximide, levetiracetam, and lacosamide. Compounds 5–38 were prepared in a coupling reaction of the 3-methyl- or 3,3-dimethyl-2-(2,5-dioxopyrrolidin-1-yl)propanoic (1, 2) or butanoic acids (3, 4) with the appropriately substituted secondary amines in the presence of the N,N-carbonyldiimidazole reagent. The initial anticonvulsant screening was performed in mice (ip) using the ‘classical’ maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) tests as well as in the six-Hertz (6 Hz) model of pharmacoresistant limbic seizures. The acute neurological toxicity was determined applying the chimney test. The broad spectra of activity across the preclinical seizure models in mice ip displayed compounds 7, 15, and 36. The most favorable anticonvulsant properties demonstrated 15 (ED50 MES = 74.8 mg/kg, ED50 scPTZ = 51.6 mg/kg, ED50 6 Hz = 16.8 mg/kg) which showed TD50 = 213.3 mg/kg in the chimney test that yielded satisfying protective indexes (PI MES = 2.85, PI scPTZ = 4.13, PI 6 Hz = 12.70) at time point of 0.5 h. As a result, compound 15 displayed comparable or better safety profile than clinically relevant AEDs: ethosuximide, lacosamide or valproic acid. In the in vitro assays compound 15 was observed as relatively effective binder to the neuronal voltage-sensitive sodium and L-type calcium channels. Beyond the anticonvulsant properties, 6 compounds diminished the pain responses in the formalin model of tonic pain in mice. 相似文献