5,520 research outputs found
An Intelligent Trade Matching System for B2B Marketplace
With the fast growth of B2B sales, an intelligent system is greatly useful for decreasing transaction cost and increasing market efficiency on electronic platforms. In order to improve the quality of transaction processing and customer experience, this paper proposes a knowledge-based system, which employs a Case-Based Reasoning (CBR) technique for trade matching in B2B marketplace as a substitute for the manual matching process. The system function and logical architecture are discussed. And the case repository is proposed to support this CBR approach where the case representation, case base indexing, case base decomposition and the dictionary are argued in details
Modeling Three-dimensional Invasive Solid Tumor Growth in Heterogeneous Microenvironment under Chemotherapy
A systematic understanding of the evolution and growth dynamics of invasive
solid tumors in response to different chemotherapy strategies is crucial for
the development of individually optimized oncotherapy. Here, we develop a
hybrid three-dimensional (3D) computational model that integrates
pharmacokinetic model, continuum diffusion-reaction model and discrete cell
automaton model to investigate 3D invasive solid tumor growth in heterogeneous
microenvironment under chemotherapy. Specifically, we consider the effects of
heterogeneous environment on drug diffusion, tumor growth, invasion and the
drug-tumor interaction on individual cell level. We employ the hybrid model to
investigate the evolution and growth dynamics of avascular invasive solid
tumors under different chemotherapy strategies. Our simulations reproduce the
well-established observation that constant dosing is generally more effective
in suppressing primary tumor growth than periodic dosing, due to the resulting
continuous high drug concentration. In highly heterogeneous microenvironment,
the malignancy of the tumor is significantly enhanced, leading to inefficiency
of chemotherapies. The effects of geometrically-confined microenvironment and
non-uniform drug dosing are also investigated. Our computational model, when
supplemented with sufficient clinical data, could eventually lead to the
development of efficient in silico tools for prognosis and treatment strategy
optimization.Comment: 41 pages, 8 figure
A transformative route to nanoporous manganese oxides of controlled oxidation states with identical textural properties
Nanoporous nanocrystalline metal oxides with tunable oxidation states are crucial for controlling their catalytic, electronic, and optical properties. However, previous approaches to modulate oxidation states in nanoporous metal oxides commonly lead to the breakdown of the nanoporous structure as well as involve concomitant changes in their morphology, pore size, surface area, and nanocrystalline size. Herein, we present a transformative route to nanoporous metal oxides with various oxidation states using manganese oxides as model systems. Thermal conversion of Mn-based metal-organic frameworks (Mn-MOFs) at controlled temperature and atmosphere yielded a series of nanoporous manganese oxides with continuously tuned oxidation states: MnO, Mn3O 4, Mn5O8, and Mn2O3. This transformation enabled the preparation of low-oxidation phase MnO and metastable intermediate phase Mn5O8 with nanoporous architectures, which were previously rarely accessible. Significantly, nanoporous MnO, Mn3O4, and Mn5O8 had a very similar morphology, surface area, and crystalline size. We investigated the electrocatalytic activity of nanoporous manganese oxides for oxygen reduction reaction (ORR) to identify the role of oxidation states, and observed oxidation state-dependent activity and kinetics for the ORR.close5
Identification by PCR signature-tagged mutagenesis of attenuated Salmonella Pullorum mutants and corresponding genes in a chicken embryo model
A key feature of the fowl-specific pathogen Salmonella Pullorum is its vertical transmission to progeny via the egg. In this study, PCR signature-tagged mutagenesis identified nine genes of a strain of S. Pullorum that contributed to survival in the chicken embryo during incubation. The genes were involved in invasion, cell division, metabolism and bacterial defence. The competition index in vivo and in vitro together with a virulence evaluation for chicken embryos of all nine mutant strains confirmed their attenuation
Transcriptomic Dissection of Sexual Differences in \u3cem\u3eBemisia tabaci\u3c/em\u3e, an Invasive Agricultural Pest Worldwide
Sex difference involving chromosomes and gene expression has been extensively documented. In this study, the gender difference in the sweetpotato whitefly Bemisia tabaci was investigated using Illumina-based transcriptomic analysis. Gender-based RNAseq data produced 27 Gb reads, and subsequent de novo assembly generated 93,948 transcripts with a N50 of 1,853 bp. A total of 1,351 differentially expressed genes were identified between male and female B. tabaci, and majority of them were female-biased. Pathway and GO enrichment experiments exhibited a gender-specific expression, including enriched translation in females, and enhanced structural constituent of cuticle in male whiteflies. In addition, a putative transformer2 gene (tra2) was cloned, and the structural feature and expression profile of tra2 were investigated. Sexually dimorphic transcriptome is an uncharted territory for the agricultural insect pests. Molecular understanding of sex determination in B. tabaci, an emerging invasive insect pest worldwide, will provide potential molecular target(s) for genetic pest control alternatives
Simultaneous thermoosmotic and thermoelectric responses in nanoconfined electrolyte solutions: Effects of nanopore structures and membrane properties
Hypothesis: Nanofluidic systems provide an emerging and efficient platform
for thermoelectric conversion and fluid pumping with low-grade heat energy. As
a basis of their performance enhancement, the effects of the structures and
properties of the nanofluidic systems on the thermoelectric response (TER) and
the thermoosmotic response (TOR) are yet to be explored. Methods: The
simultaneous TER and TOR of electrolyte solutions in nanofluidic membrane pores
on which an axial temperature gradient is exerted are investigated numerically
and semi-analytically. A semi-analytical model is developed with the
consideration of finite membrane thermal conductivity and the
reservoir/entrance effect. Findings: The increase in the access resistance due
to the nanopore-reservoir interfaces accounts for the decrease of short circuit
current at the low concentration regime. The decrease in the thermal
conductivity ratio can enhance the TER and TOR. The maximum power density
occurring at the nanopore radius twice the Debye length ranges from several to
dozens of mW K m and is an order of magnitude higher than typical
thermo-supercapacitors. The surface charge polarity can heavily affect the sign
and magnitude of the short-circuit current, the Seebeck coefficient, and the
open-circuit thermoosmotic coefficient, but has less effect on the
short-circuit thermoosmotic coefficient. Furthermore, the membrane thickness
makes different impacts on TER and TOR for zero and finite membrane thermal
conductivity.Comment: 38 pages, 10 figure
Ethyl 2-[(Z)-2-benzylhydrazin-1-ylidene]-2-bromoacetate
In the title compound, C11H13BrN2O2, the dihedral angle between the phenyl ring and the almost planar (r.m.s. deviation = 0.011 Å) C—C(Br)=N—N(H)— fragment is 74.94 (16)°. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, which generate C(6) chains propagating in [010]. Weak aromatic π–π stacking [centroid–centroid separation = 3.784 (3) Å] may also help to consolidate the packing
Different nitrogen saturation thresholds for above-, below-, and total net primary productivity in a temperate steppe
Identifying the thresholds for the positive responses of total net primary productivity (NPP) to nitrogen (N) enrichment is an essential prerequisite for predicting the benefits of N deposition on ecosystem carbon sequestration. However, the responses of below-ground NPP (BNPP) to N enrichment are unknown in many ecosystems, which limits our ability to understand the carbon cycling under the scenario of increasing N availability. We examined the changes in above-ground NPP (ANPP), BNPP, and NPP of a temperate meadow steppe across a wide-ranging N addition gradient (0, 2, 5, 10, 20, and 50 g N m -2 year -1 ) during 5 years. Both ANPP and NPP increased nonlinearly with N addition rates. The N saturation threshold for ANPP (T A ) and NPP (T N ) was at the rate of 13.11 and 6.70 g N m -2 year -1 , respectively. BNPP decreased with increasing N addition when N addition rates ˃5 g N m -2 year -1 , resulting in much lower T N than T A . Soil N enrichment played a key role in driving the negative impacts of high N addition rates on BNPP, and consequently on the earlier occurrence of N saturation threshold for NPP. Our results highlight the negative effects of soil N enrichment on NPP in natural grasslands super-saturated with N. Furthermore, by considering ANPP and BNPP simultaneously, our results indicate that previous findings from above-ground might have over-estimated the positive effects of N deposition on primary productivity
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