高电压十二相可逆电路的环流

讨论了高电压十二相可逆电路的环流问题 ,给出了环流波形图 ,并简要说明了波形图的使用方法 .所得结论可为工程技术人员设计系统提供方便 .     

公交IC卡收费系统与客流数据采集、处理

根据目前国内公交收费的发展趋势,设计出用于对客流等数据采集的IC卡自动收费系统,并提出利用它来进行客流等数据采集、处理的新方案.与人工调查相比,它的投入小得多,并且可以提供大量详细、准确的动态数据,对城市公交以及公交的智能化调度、线路的开辟、优化、站点的设置等都具有极其重要的意义.     

The stoichiometry of peptide-heparan sulfate binding as a determinant of uptake efficiency of cell-penetrating peptides

Binding to negatively charged heparan sulfates (HS) at the cell surface is considered the first step in the internalization of cationic cell-penetrating peptides (CPPs). However, little is known about the relation of the characteristics of the HS-CPP interaction such as affinity, stoichiometry, and clustering with uptake. In this study, we investigated a collection of mutants of a cyclic CPP derived from human lactoferrin with respect to HS binding and uptake. The thermodynamic parameters of HS binding were determined by isothermal titration calorimetry, clustering of HS was investigated by dynamic light scattering, and cellular uptake by flow cytometry and confocal microscopy. Whereas mutations of non-arginine amino acids that are conserved across lactoferrins of different mammalia only had a minor effect on uptake efficiency, changes in the number of arginine residues influenced the uptake significantly. In general, introduction of arginine residues and cyclization improved the HS affinity and the ability to cluster HS. In particular, there was a strong negative correlation between stoichiometry and uptake, indicating that crosslinking of HS is the driving force for the uptake of arginine-rich CPPs. Using glycan microarrays presenting a collection of synthetic HS, we show that a minimal chain length of HS is required for peptide binding.     

Acetylation-dependent regulation of endothelial Notch signalling by the SIRT1 deacetylase

Notch signalling is a key intercellular communication mechanism that is essential for cell specification and tissue patterning, and which coordinates critical steps of blood vessel growth. Although subtle alterations in Notch activity suffice to elicit profound differences in endothelial behaviour and blood vessel formation, little is known about the regulation and adaptation of endothelial Notch responses. Here we report that the NAD(+)-dependent deacetylase SIRT1 acts as an intrinsic negative modulator of Notch signalling in endothelial cells. We show that acetylation of the Notch1 intracellular domain (NICD) on conserved lysines controls the amplitude and duration of Notch responses by altering NICD protein turnover. SIRT1 associates with NICD and functions as a NICD deacetylase, which opposes the acetylation-induced NICD stabilization. Consequently, endothelial cells lacking SIRT1 activity are sensitized to Notch signalling, resulting in impaired growth, sprout elongation and enhanced Notch target gene expression in response to DLL4 stimulation, thereby promoting a non-sprouting, stalk-cell-like phenotype. In vivo, inactivation of Sirt1 in zebrafish and mice causes reduced vascular branching and density as a consequence of enhanced Notch signalling. Our findings identify reversible acetylation of the NICD as a molecular mechanism to adapt the dynamics of Notch signalling, and indicate that SIRT1 acts as rheostat to fine-tune endothelial Notch responses.     

Persistence of soil organic matter as an ecosystem property

Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily--and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming.     

Exome sequencing identifies ACAD9 mutations as a cause of complex I deficiency

An isolated defect of respiratory chain complex I activity is a frequent biochemical abnormality in mitochondrial disorders. Despite intensive investigation in recent years, in most instances, the molecular basis underpinning complex I defects remains unknown. We report whole-exome sequencing of a single individual with severe, isolated complex I deficiency. This analysis, followed by filtering with a prioritization of mitochondrial proteins, led us to identify compound heterozygous mutations in ACAD9, which encodes a poorly understood member of the mitochondrial acyl-CoA dehydrogenase protein family. We demonstrated the pathogenic role of the ACAD9 variants by the correction of the complex I defect on expression of the wildtype ACAD9 protein in fibroblasts derived from affected individuals. ACAD9 screening of 120 additional complex I-defective index cases led us to identify two additional unrelated cases and a total of five pathogenic ACAD9 alleles.     

Influence of prey movement on the aim of predatory strikes of the western rattlesnake ( Crotalus Viridis )

The purpose of this study was to determine whether the western rattlesnake ( Crotalus viridis ) aims its predatory strike at the head/thorax region of mice primarily on the basis of cues related to the direction of prey movement. We hypothesized that when rattlesnakes strike at anesthetized, backward-moving mice, most strikes would be aimed at the forward-most-moving region, i.e., the posterior (abdomen/tail) region of prey. However, most mice were struck in the anterior (head/thorax) region, implying that the visual-infrared image of mice, rather than directional movement, guides the aim of predatory strikes.     

Evidence for a spectral basis of texture perception in bat sonar

Bats obtain information about the structure of objects in the outside world from their echolocation signals, an extremely useful method when hunting non-flying prey in densely cluttered habitats, for example. Information about object structure is contained both in the time and in the spectral interference patterns of signals reflected from surfaces at different distances from the bat. I report here an experiment designed to test the extent to which bats use these two types of information. A 'phantom target' is generated by playing back to an echolocating bat signals that mimic the result of reflection from two planes set at different distances. The ability of the bat to discriminate between two such targets is investigated as a function of the separations of the planes. Several of the results do not fit the hypothesis that the bat simply uses time-delay information: the very small time difference that can be discriminated, the fall off in ability to discriminate planes at a particular separation and the symmetry of the discrimination ability measured in the frequency domain. The empirical data can best be fitted by a function based on spectral correlation.     

RAGE is a multiligand receptor of the immunoglobulin superfamily: implications for homeostasis and chronic disease

Receptor for AGE (RAGE) is a member of the immunoglobulin superfamily that engages distinct classes of ligands. The biology of RAGE is driven by the settings in which these ligands accumulate, such as diabetes, inflammation, neurodegenerative disorders and tumors. In this review, we discuss the context of each of these classes of ligands, including advance glycation end-products, amyloid beta peptide and the family of beta sheet fibrils, S100/calgranulins and amphoterin. Implications for the role of these ligands interacting with RAGE in homeostasis and disease will be considered.