3,573 research outputs found
Accurate prediction of heat of formation by combining Hartree-Fock/density functional theory calculation with linear regression correction approach
A linear regression correction (LRC) approach was developed to account for the electron correlation energy missing in Hartree-Fock (HF) calculation. This method was applied to evaluate the standard heats of formation of 180 small-sized to medium-sized organic molecules at 298.15 K. The descriptors in the LRC scheme are the number of lone-pair electrons, bonding electrons and inner layer electrons in molecules, and the number of unpaired electrons in ground state atoms. It is observed that the large systematic deviations for the calculated heat of formation are reduced drastically, in particular, for the HF results.published_or_final_versio
Modeling the scaling properties of human mobility
While the fat tailed jump size and the waiting time distributions
characterizing individual human trajectories strongly suggest the relevance of
the continuous time random walk (CTRW) models of human mobility, no one
seriously believes that human traces are truly random. Given the importance of
human mobility, from epidemic modeling to traffic prediction and urban
planning, we need quantitative models that can account for the statistical
characteristics of individual human trajectories. Here we use empirical data on
human mobility, captured by mobile phone traces, to show that the predictions
of the CTRW models are in systematic conflict with the empirical results. We
introduce two principles that govern human trajectories, allowing us to build a
statistically self-consistent microscopic model for individual human mobility.
The model not only accounts for the empirically observed scaling laws but also
allows us to analytically predict most of the pertinent scaling exponents
Microdevices for extensional rheometry of low viscosity elastic liquids : a review
Extensional flows and the underlying stability/instability mechanisms are of extreme relevance to the efficient operation of inkjet printing, coating processes and drug delivery systems, as well as for the generation of micro droplets. The development of an extensional rheometer to characterize the extensional properties of low viscosity fluids has therefore stimulated great interest of researchers, particularly in the last decade. Microfluidics has proven to be an extraordinary working platform and different configurations of potential extensional microrheometers have been proposed. In this review, we present an overview of several successful designs, together with a critical assessment of their capabilities and limitations
Dominant features in three-dimensional turbulence structure: comparison of non-uniform accelerating and decelerating flows
The results are presented from an experimental study to investigate three-dimensional turbulence structure profiles, including turbulence intensity and Reynolds stress, of different non-uniform open channel flows over smooth bed in subcritical flow regime. In the analysis, the uniform flow profiles have been used to compare with those of the non-uniform flows to investigate their time-averaged spatial flow turbulence structure characteristics. The measured non-uniform velocity profiles are used to verify the von Karman constant κ and to estimate sets of log-law integration constant B r and wake parameter П, where their findings are also compared with values from previous studies. From κ, B r and П findings, it has been found that the log-wake law can sufficiently represent the non-uniform flow in its non-modified form, and all κ, B r and П follow universal rules for different bed roughness conditions. The non-uniform flow experiments also show that both the turbulence intensity and Reynolds stress are governed well by exponential pressure gradient parameter β equations. Their exponential constants are described by quadratic functions in the investigated β range. Through this experimental study, it has been observed that the decelerating flow shows higher empirical constants, in both the turbulence intensity and Reynolds stress compared to the accelerating flow. The decelerating flow also has stronger dominance to determine the flow non-uniformity, because it presents higher Reynolds stress profile than uniform flow, whereas the accelerating flow does not
Effects of Thioglycolic Acid on Parthenogenetic Activation of Xenopus Oocytes
BACKGROUND: Existing in Permanent-wave solutions (PWS), thioglycolic acid (TGA) is widely used in hairdressing industry for its contribution to hair styling. However, the toxicity of TGA, especially its reproductive toxicity, gradually calls the attention of more and more researchers. METHOD: In this work, xenopus oocytes were pretreated with different concentration of TGA, and then activated by calcium ionophore A23187. During culture, the oocytes activation rates were taken note at different time after adding calcium ionophore A23187. At the end of the culture period, the nuclear status was detected under confocal microscope. In addition, some other samples were collected for Western-Blotting analysis. RESULT: TGA significantly inhibited the oocytes activation rate and pronuclear formation. It may be resulted from the inhibition of the degradation of p-ERK1, Mos and CyclinB2. CONCLUSION: TGA inhibits in vitro parthenogenetic activation of xenopus oocytes with inhibited the degradation of proteins involved in mitogenic-activated protein kinase (MAPK) and maturation-promoting factor (MPF) pathways
A massive urban symbiosis:A preliminary review of the Urban Mining Pilot Bases Programme in China
Waste recycling helps to establish a circular loop of resource flow between production and consumption, achieving a certain symbiosis between the industrial and urban sector. Since more and more resources are accumulated in the urban sector, urban mining as form of waste recycling in a massive way becomes an outstanding way to achieve industrial and urban symbiosis. In 2010 China initiated a national urban mining pilot base (UMPB) programme with the objective of developing the recycling industry and relieving environmental and resource constrains. This study aims to provide policy review of the programme. We find that the UMPB programme was developed from past circular economy policies and attains legacy assurance from current laws and national plans. But this did not formulate a perfect governance context for its implementation. A multi-ministerial cross-management network led to policy conflicts, and recycling-oriented legislation remained absent. These became the main barriers for the good implementation of those urban mining pilots. Comparing with the eco-town programme in Japan, it shows that both programmes share some similarities of partial policy objectives but also show variety in the scope of urban symbiosis due to the different problems they focus on and the slightly different policy objectives under the different economic and social development phases
Two novel human cytomegalovirus NK cell evasion functions target MICA for lysosomal degradation
NKG2D plays a major role in controlling immune responses through the regulation of natural killer (NK) cells, αβ and γδ T-cell function. This activating receptor recognizes eight distinct ligands (the MHC Class I polypeptide-related sequences (MIC) A andB, and UL16-binding proteins (ULBP)1–6) induced by cellular stress to promote recognition cells perturbed by malignant transformation or microbial infection. Studies into human cytomegalovirus (HCMV) have aided both the identification and characterization of NKG2D ligands (NKG2DLs). HCMV immediate early (IE) gene up regulates NKGDLs, and we now describe the differential activation of ULBP2 and MICA/B by IE1 and IE2 respectively. Despite activation by IE functions, HCMV effectively suppressed cell surface expression of NKGDLs through both the early and late phases of infection. The immune evasion functions UL16, UL142, and microRNA(miR)-UL112 are known to target NKG2DLs. While infection with a UL16 deletion mutant caused the expected increase in MICB and ULBP2 cell surface expression, deletion of UL142 did not have a similar impact on its target, MICA. We therefore performed a systematic screen of the viral genome to search of addition functions that targeted MICA. US18 and US20 were identified as novel NK cell evasion functions capable of acting independently to promote MICA degradation by lysosomal degradation. The most dramatic effect on MICA expression was achieved when US18 and US20 acted in concert. US18 and US20 are the first members of the US12 gene family to have been assigned a function. The US12 family has 10 members encoded sequentially through US12–US21; a genetic arrangement, which is suggestive of an ‘accordion’ expansion of an ancestral gene in response to a selective pressure. This expansion must have be an ancient event as the whole family is conserved across simian cytomegaloviruses from old world monkeys. The evolutionary benefit bestowed by the combinatorial effect of US18 and US20 on MICA may have contributed to sustaining the US12 gene family
Echocardiography in the diagnosis left ventricular noncompaction
Echocardiography is the method of choice to establish a diagnosis and determine a treatment plan for patients with noncompaction of ventricular myocardium (NVM). The 2-dimentional echocardiography, 3-dimentional echocardiography, color Doppler echocardiography and contrast-enhanced echocardiography are of critical importance for diagnosis and family screening of NVM
Superoxide dismutase A antigens derived from molecular analysis of sarcoidosis granulomas elicit systemic Th-1 immune responses
<p>Abstract</p> <p>Background</p> <p>Sarcoidosis is an idiopathic granulomatous disease with pathologic and immunologic features similar to tuberculosis. Routine histologic staining and culture fail to identify infectious agents. An alternative means for investigating a role of infectious agents in human pathogenesis involves molecular analysis of pathologic tissues for microbial nucleic acids, as well as recognition of microbial antigens by the host immune system. Molecular analysis for superoxide dismutase A (sodA) allows speciation of mycobacteria. SodA is an abundantly secreted virulence factor that generates cellular immune responses in infected hosts. The purpose of this study is to investigate if target antigens of the sarcoidosis immune response can be identified by molecular analysis of sarcoidosis granulomas.</p> <p>Methods</p> <p>We detected sodA amplicons in 12 of 17 sarcoidosis specimens, compared to 2 of 16 controls (p = 0.001, two-tailed Fisher's exact test), and 3 of 3 tuberculosis specimens (p = 0.54). Analysis of the amplicons revealed sequences identical to <it>M. tuberculosis </it>(MTB) complex, as well as sequences which were genetically divergent. Using peripheral blood mononuclear cells (PBMC) from 12 of the 17 sarcoidosis subjects, we performed enzyme-linked immunospot assay (ELISPOT) to assess for immune recognition of MTB sodA peptides, along with PBMC from 26 PPD- healthy volunteers, and 11 latent tuberculosis subjects.</p> <p>Results</p> <p>Six of 12 sarcoidosis subjects recognized the sodA peptides, compared to one of 26 PPD- controls (p = 0.002), and 6/11 PPD+ subjects (p = .68). Overall, 10 of the 12 sarcoidosis subjects from whom we obtained PBMC and archival tissue possessed molecular or immunologic evidence for sodA.</p> <p>Conclusion</p> <p>Dual molecular and immunologic analysis increases the ability to find infectious antigens. The detection of Th-1 immune responses to sodA peptides derived from molecular analysis of sarcoidosis granulomas reveals that these are among the target antigens contributing to sarcoidosis granulomatous inflammation.</p
Gastrin stabilises β-catenin protein in mouse colorectal cancer cells
As gastrin may play a role in the pathophysiology of gastrointestinal (GI) malignancies, the elucidation of the mechanisms governing gastrin-induced proliferation has recently gained considerable interest. Several studies have reported that a large percentage of colorectal tumours overexpress or stabilise the β-catenin oncoprotein. We thus sought to determine whether gastrin might regulate β-catenin expression in colorectal tumour cells. Amidated gastrin-17 (G-17), one of the major circulating forms of gastrin, not only enhanced β-catenin protein expression, but also one of its target genes, cyclin D1. Furthermore, activation of β-catenin-dependent transcription by gastrin was confirmed by an increase in LEF-1 reporter activity, as well as enhanced cyclin D1 promoter activity. Finally, G-17 prolonged the τ1/2 of β-catenin protein, demonstrating that gastrin appears to exert its mitogenic effects on colorectal tumour cells, at least in part, by stabilising β-catenin
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