A Review of Molybdenum Adsorption in Soils/Bed Sediments: Speciation,Mechanism, and Model Applications

Mo is an essential trace element for both plants and animals in low concentrations (<5 ppm). However, provoked by uncontrolled industrial waste releases in freshwater or seawater, it is plausible that excessive availability of soluble Mo(VI) would be potentially toxic. In the environment, soluble Mo(VI) is mainly present in anionic forms of molybdate (MoO₄ ^2?) and/or tetrathiomolybdate (MoS₄ ^2?). The fate and transport of soluble Mo(VI) anions in surface and subsurface aquatic environments is typically controlled by adsorption in acidic soils and sediment. As such, the ability of soils/bed sediments to retain Mo(VI) is a key to determine its general mobility in the aquatic environment. This article reviews the sources and distribution of Mo speciation in solution and Mo(VI) anions adsorption mechanisms in soils and bed sediments, and evaluates the surface adsorption complexation models at the solid-water interface to estimate Mo(VI) anions adsorption in these chemical systems. Mo(VI) anions adsorption mechanisms included MoO₄ ^2? and MoS₄ ^2? adsorption by several prevailing adsorbent contents (including clay, Fe, Al oxides, iron sulfide, manganese oxides, and organic matter) of soils and bed sediments, and the influence of the competitive adsorption of other anions (e.g., sulfate, selenate, phosphate, arsenate, silicate, or tungstate). Models to estimate Mo(VI) anions adsorption include the triple layer model (TLM), the diffuse layer model (DLM), the constant capacitance surface complexation model (CCM), and charge distribution multisite complexation model (CD-MUSIC).     

A Model for DNA Sequence Evolution within Transposable Element Families

A quantitative model is proposed for the expected degree of relationship between copies of a family of transposable elements in a finite population of hosts. Special cases of the model (in which the process of homogenization of element copies either is or is not limited by transposition rate) are presented and illustrated, using data on mobile sequences from different species. It is shown that transposition will be expected, in large populations, to result in only a rather distant relationship between transposable elements at different genomic sites. Possible inadequacies of the model are suggested and quantified.     

随机时滞Lotka-Volterra模型数值解的收敛性

通常情况下,随机时滞Lotka-Volterra模型没有解析解,因而数值逼近方法是研究其性质的有效工具.本文根据Euler数值方法,利用鞅不等式和Ito公式讨论了一类随机时滞Lotka-Volterra模型数值解的收敛性,给出了数值解收敛于解析解的条件.最后通过数值算例对数值计算方法进行了验证.     

A Point-Wise Model of Adhesion Suitable for Real-Time Applications of Bio-Inspired Climbing Robots

Bio-inspired climbing robots relying on adhesion systems are believed to become essential tools for several industrial applications in the near future. In recent years, research has mainly focused on modeling micro-scale adhesion phenomena; a macro-scale adhesion model has however to be developed for the design of macro-scale systems. In this paper a macro-model of adhesion suitable for real-time applications is presented; it relies on a continuous representation of adhesion. An extension of the von Mises criterion is proposed as failure adhesion criterion in order to estimate the occurrence of detachment at any point of the contacting surface. An experimental set up has been designed in order to define the parameters of the model. A semi-automatic process has been developed to ensure repeatability and accuracy of the results. Polydimethylsiloxane (PDMS), which has revealed promising adhesive features for robotic use, has been used during the experimental phase. The macro-model of adhesion has been implemented in a multi-body dynamics environment based on Open Dynamics Engine (ODE) to simulate a spider-inspired robot. Simulations based on this model are suitable to represent the behaviour of climbing robots and also to optimize their design.     

A Mixed Model of Mutation for Electrophoretic Identity of Proteins within and between Populations

A model which is a mixture of the model of infinite alleles and the Ohta-Kimura model of stepwise mutation has been proposed for the study of eletcrophoretic variants in natural populations. Mutations which alter the mobility of a protein are divided into two classes: stepwise mutations and nonstepwise mutations. It is assumed that stepwise mutations follow the Ohta-Kimura model while nonstepwise mutations follow the infinite allele model. It is then shown that even if the proportion of nonstepwise mutations is only 5%, with the other 95% stepwise mutations, the effective number of alleles given by the present model is considerably larger than that given by the Ohta-Kimura model of stepwise mutation. The result has also been applied to study Nei's genetic distance.     

A Comparison of the Spatial Linear Model to Nearest Neighbor (k-NN) Methods for Forestry Applications

Forest surveys provide critical information for many diverse interests. Data are often collected from samples, and from these samples, maps of resources and estimates of aerial totals or averages are required. In this paper, two approaches for mapping and estimating totals; the spatial linear model (SLM) and k-NN (k-Nearest Neighbor) are compared, theoretically, through simulations, and as applied to real forestry data. While both methods have desirable properties, a review shows that the SLM has prediction optimality properties, and can be quite robust. Simulations of artificial populations and resamplings of real forestry data show that the SLM has smaller empirical root-mean-squared prediction errors (RMSPE) for a wide variety of data types, with generally less bias and better interval coverage than k-NN. These patterns held for both point predictions and for population totals or averages, with the SLM reducing RMSPE from 9% to 67% over some popular k-NN methods, with SLM also more robust to spatially imbalanced sampling. Estimating prediction standard errors remains a problem for k-NN predictors, despite recent attempts using model-based methods. Our conclusions are that the SLM should generally be used rather than k-NN if the goal is accurate mapping or estimation of population totals or averages.     

Romulus and Remus,Two Phage Isolates Representing a Distinct Clade within the Twortlikevirus Genus,Display Suitable Properties for Phage Therapy Applications

The renewed interest in controlling Staphylococcus aureus infections using their natural enemies, bacteriophages, has led to the isolation of a limited number of virulent phages so far. These phages are all members of the Twortlikevirus, displaying little variance. We present two novel closely related (95.9% DNA homology) lytic myoviruses, Romulus and Remus, with double-stranded DNA (dsDNA) genomes of 131,333 bp and 134,643 bp, respectively. Despite their relatedness to Staphylococcus phages K, G1, ISP, and Twort and Listeria phages A511 and P100, Romulus and Remus can be proposed as isolates of a new species within the Twortlikevirus genus. A distinguishing feature for these phage genomes is the unique distribution of group I introns compared to that in other staphylococcal myoviruses. In addition, a hedgehog/intein domain was found within their DNA polymerase genes, and an insertion sequence-encoded transposase exhibits splicing behavior and produces a functional portal protein. From a phage therapy application perspective, Romulus and Remus infected approximately 70% of the tested S. aureus isolates and displayed promising lytic activity against these isolates. Furthermore, both phages showed a rapid initial adsorption and demonstrated biofilm-degrading capacity in a proof-of-concept experiment.     

Functional Roles for Synaptic-Depression within a Model of the Fly Antennal Lobe

Several experiments indicate that there exists substantial synaptic-depression at the synapses between olfactory receptor neurons (ORNs) and neurons within the drosophila antenna lobe (AL). This synaptic-depression may be partly caused by vesicle-depletion, and partly caused by presynaptic-inhibition due to the activity of inhibitory local neurons within the AL. While it has been proposed that this synaptic-depression contributes to the nonlinear relationship between ORN and projection neuron (PN) firing-rates, the precise functional role of synaptic-depression at the ORN synapses is not yet fully understood. In this paper we propose two hypotheses linking the information-coding properties of the fly AL with the network mechanisms responsible for ORN[Formula: see text]AL synaptic-depression. Our first hypothesis is related to variance coding of ORN firing-rate information - once stimulation to the ORNs is sufficiently high to saturate glomerular responses, further stimulation of the ORNs increases the regularity of PN spiking activity while maintaining PN firing-rates. The second hypothesis proposes a tradeoff between spike-time reliability and coding-capacity governed by the relative contribution of vesicle-depletion and presynaptic-inhibition to ORN[Formula: see text]AL synaptic-depression. Synaptic-depression caused primarily by vesicle-depletion will give rise to a very reliable system, whereas an equivalent amount of synaptic-depression caused primarily by presynaptic-inhibition will give rise to a less reliable system that is more sensitive to small shifts in odor stimulation. These two hypotheses are substantiated by several small analyzable toy models of the fly AL, as well as a more physiologically realistic large-scale computational model of the fly AL involving [Formula: see text] glomerular channels.     

A Determinative Scheme for the Fluorescent Plant Pathogenic Pseudomonads

S ummary . The differential value of 15 characteristics was studied for the determination of plant pathogens in the fluorescent group of the genus Pseudomonas. All but 2 of the 161 pathogenic cultures and the 15 nonpathogenic cultures examined could be placed in one of 5 groups on the basis of tests for: oxidase, potato soft rot, arginine dihydrolase, levan production and a hypersensitivity reaction in tobacco leaves. Tests for production of acid from sucrose, nitrate reductase and a lipase for margarine were useful as subsidiary determinants. Aesculin hydrolysis, gelatinase and tyrosinase tests, and the production of a blue fluorescent pigment were of little or no value at the group level, and hydrolysis of Tween 80 and the catalase reaction had no differential value. With the exception of Ps. tolaaii and two cultures of questionable pathogenicity, the pathogens studied could be separated readily from the few nonpathogens studied. A determinative scheme for plant pathogenic fluorescent pseudomonads is proposed to serve until the taxonomy of the group is better understood.     

一种预测个体肿瘤的抗癌药物反应分类计算模型及其应用

目的 不同患者对同一抗癌药物的反应可能不同,了解患者之间对抗癌药物的反应差异对癌症精准医疗具有重大参考价值。方法 高通量测序数据为构建抗癌药物反应分类预测模型提供了强大的数据支撑。针对两大经典数据集癌症细胞百科全书(CCLE)和癌症药物敏感性基因组学数据集(GDSC),本文提出了基于最大相关最小冗余(mRMR)算法和支持向量机(SVM)的计算模型mRMR-SVM。利用基因表达数据,通过方差排序和mRMR算法提取特征基因,借助SVM实现抗癌药物对细胞系的“敏感-抑制”二分类预测。结果 对于CCLE中的22种药物,mRMR-SVM的平均准确率为0.904;对于GDSC中的11种药物,平均准确率为0.851。结论 mRMR-SVM不仅在预测性能方面优于传统的支持向量机、随机森林、深度反应森林、深度神经网络和细胞系-药物复杂网络模型,而且具有良好的泛化能力,对于三类特定组织的抗癌药物反应分类预测也取得了令人满意的结果。此外,mRMR-SVM可以识别与癌症发生发展密切相关的生物标志物。     

Studying the Structural,Morphological, Optical,and Electrical Properties of CdS/PbS Thin Films for Photovoltaic Applications

Plasmonics - The cadmium sulfide (CdS) and lead sulfide (PbS) materials have been chosen in order to boost solar energy conversion from ultraviolet region to the near-infrared (NIR) spectral...     

PAH基因内一个A／C多态性位点的分析

在苯丙氨酸羟化酶基因ＩＶＳ３的３‘端－１１位有一个Ａ／Ｃ多态性位点,应用ＳＳＣＰ分析可进行简便检测,Ａ等位基因的频率为０．６５６,Ｃ等位基因的频率为０．３４４,此位点的多态性信息含量（ＰＩＣ）为０．３５１。Ａ／Ｃ位点与同一内含子内的ＳＴＲ位点间没有连锁不平衡性,联合应用这两个多态性位点进行单体型连锁分析,对ＰＫＵ家系进行产前基断诊断率可达７５％。     

Phylogeny, biogeography, and species boundaries within the Alexandrium minutum group

The geographic range and bloom frequency of the toxic dinoflagellate Alexandrium minutum and other members of the A. minutum group have been increasing over the past few decades. Some of these species are responsible for paralytic shellfish poisoning (PSP) outbreaks throughout the world. The origins of new toxic populations found in previously unaffected areas are typically not known due to a lack of reliable plankton records with sound species identifications and to the lack of a global genetic database. This paper provides the first comprehensive study of minutum-group morphology and phylogeny on a global scale, including 45 isolates from northern Europe, the Mediterranean, Asia, Australia and New Zealand.Neither the morphospecies Alexandrium lusitanicum nor A. angustitabulatum was recoverable morphologically, due to large variation within and among all minutum-group clonal strains in characters previously used to distinguish these species: the length:width of the anterior sulcal plate, shape of the 1′ plate, connection between the 1′ plate and the apical pore complex, and the presence of a ventral pore. DNA sequence data from the D1 to D2 region of the LSU rDNA also fail to recognize these species. Therefore, we recommend that all isolates previously designated as A. lusitanicum or A. angustitabulatum be redesignated as A. minutum. A. tamutum, A. insuetum, and A. andersonii are clearly different from A. minutum on the basis of both genetic and morphological data.A. minutum strains from Europe and Australia are closely related to one another, which may indicate an introduction from Europe to Australia given the long history of PSP in Europe and its recent occurrence in Australia. A minutum from New Zealand and Taiwan form a separate phylogenetic group. Most strains of A. minutum fit into one of these two groups, although there are a few outlying strains that merit further study and may represent new species. The results of this paper have greatly improved our ability to track the spread of A. minutum species and to understand the evolutionary relationships within the A. minutum group by correcting inaccurate taxonomy and providing a global genetic database.     

A positively charged channel within the Smc1/Smc3 hinge required for sister chromatid cohesion

Cohesin's structural maintenance of chromosome 1 (Smc1) and Smc3 are rod-shaped proteins with 50-nm long intra-molecular coiled-coil arms with a heterodimerization domain at one end and an ABC-like nucleotide-binding domain (NBD) at the other. Heterodimerization creates V-shaped molecules with a hinge at their centre. Inter-connection of NBDs by Scc1 creates a tripartite ring within which, it is proposed, sister DNAs are entrapped. To investigate whether cohesin's hinge functions as a possible DNA entry gate, we solved the crystal structure of the hinge from Mus musculus, which like its bacterial counterpart is characterized by a pseudo symmetric heterodimeric torus containing a small channel that is positively charged. Mutations in yeast Smc1 and Smc3 that together neutralize the channel's charge have little effect on dimerization or association with chromosomes, but are nevertheless lethal. Our finding that neutralization reduces acetylation of Smc3, which normally occurs during replication and is essential for cohesion, suggests that the positively charged channel is involved in a major conformational change during S phase.