A QSAR Study of Environmental Estrogens Based on a Novel Variable Selection Method

A large number of descriptors were employed to characterize the molecular structure of 53 natural, synthetic, and environmental chemicals which are suspected of disrupting endocrine functions by mimicking or antagonizing natural hormones and may thus pose a serious threat to the health of humans and wildlife. In this work, a robust quantitative structure-activity relationship (QSAR) model with a novel variable selection method has been proposed for the effective estrogens. The variable selection method is based on variable interaction (VSMVI) with leave-multiple-out cross validation (LMOCV) to select the best subset. During variable selection, model construction and assessment, the Organization for Economic Co-operation and Development (OECD) principles for regulation of QSAR acceptability were fully considered, such as using an unambiguous multiple-linear regression (MLR) algorithm to build the model, using several validation methods to assessment the performance of the model, giving the define of applicability domain and analyzing the outliers with the results of molecular docking. The performance of the QSAR model indicates that the VSMVI is an effective, feasible and practical tool for rapid screening of the best subset from large molecular descriptors

A QSAR Study of Environmental Estrogens Based on a Novel Variable Selection Method

A large number of descriptors were employed to characterize the molecular structure of 53 natural, synthetic, and environmental chemicals which are suspected of disrupting endocrine functions by mimicking or antagonizing natural hormones and may thus pose a serious threat to the health of humans and wildlife. In this work, a robust quantitative structure-activity relationship (QSAR) model with a novel variable selection method has been proposed for the effective estrogens. The variable selection method is based on variable interaction (VSMVI) with leave-multiple-out cross validation (LMOCV) to select the best subset. During variable selection, model construction and assessment, the Organization for Economic Co-operation and Development (OECD) principles for regulation of QSAR acceptability were fully considered, such as using an unambiguous multiple-linear regression (MLR) algorithm to build the model, using several validation methods to assessment the performance of the model, giving the define of applicability domain and analyzing the outliers with the results of molecular docking. The performance of the QSAR model indicates that the VSMVI is an effective, feasible and practical tool for rapid screening of the best subset from large molecular descriptors

Emerging mineral-coupled composite phase change materials for thermal energy storage

A mineral-coupled support, flake graphite-carbon nanofiber-modified bentonite, was used to stabilize stearic acid for constructing form-stable phase change material composites. In order to achieve a synergistic improvement of thermal conductivity and loading space, the supporting material was prepared by growing carbon nanofiber on flake graphite surface through chemical vapor deposition technique and then chemically bonding with modified bentonite. The effect of coupling behavior on interfacial thermal resistance was investigated and results show that the thermal conductivity of the coupled supporting material (4.595 W m−1 K−1) is higher than that of non-coupled support (4.291 W m−1 K−1), proving chemical bonding can decrease interface thermal resistance at a certain extent. The performances of composites were further explored, which indicates the obtained composite base on coupled support possesses good chemical compatibility, and great thermal stability under 180 °C. It also shows that this composite with 41.90% loading capability has latent heat value of 79.13 J g−1 for melting and 79.13 J g−1 for freezing, respectively. After 50 heating-cooling cycles, the variation of melting latent heat was within 0.05%, exhibiting a great thermal reliability. Besides, thermal conductivity of this composite is 10.50 times higher than that of pure phase change material, resulting in more rapid heat transfer efficiency, and excellent transient temperature response recorded by thermal infrared images. In all, the composite is a potential candidate for thermal storage applications due to larger latent heat capability and considerable thermal conductivity.This work was supported by the National Natural Science Foundation of China, China (51504041, 51874047); the Training Program for Excellent Young Innovators of Changsha (kq1802007); the Fund for University Young Core Instructors of Hunan Province, China; the Natural Science Foundation of Hunan Province (2016JJ3009); the Key Research and Development Program of Jiangxi Province, China (20171BBH80021); and the Hunan Province 2011 Collaborative Innovation Center of Clean Energy and Smart Grid

Stearic acid/expanded graphite as a composite phase change thermal energy storage material for tankless solar water heater

Tankless solar water heater (TSWH) integrated phase change materials (PCMs) is a promising field due to its low cost, low heat loss, and compact structure. To obtain a composite PCMs that suitable for tankless solar water heater application, the expanded graphite (EG) in different mass fraction (2 wt.%, 6 wt.%, and 10 wt.%) were added to stearic acid (SA) via melting impregnation. The thermophysical properties including phase change temperature, latent heat, and thermal conductivity of the SA/EG composites were characterized by DSC and thermal conductivity tests. The melting and freezing heats of SA/EG6 composite were 163.5 J g−1 and 167.3 J g−1, respectively. The thermal conductivity of SA/EG6 was as high as 9.6 times that of pure SA. Meanwhile, the infrared images suggested the addition of EG enhance the heat release capability of composites as well as improve the uniformity of heat transfer process of SA/EG6. At last, a developed compact solar water heater was used to estimate the thermal performance of as-prepared composites. The experimental results shown that the melting time of SA/EG6 was shorten 63.3% compared with that of the SA and the heat releasing rate of SA/EG6 was the highest, suggesting the SA/EG6 composites can be applied in TSWH system.This work was supported by the National Natural Science Foundation of China (51504041, 51874047); the Changsha City Fund for Distinguished and Innovative Young Scholars; the Fund for University Young Core Instructors of Hunan Province; the Natural Science Foundation of Hunan Province (2016JJ3009); the Key Research and Development Program of Jiangxi Province (20171BBH80021); and the Hunan Province 2011 Collaborative Innovation Center of Clean Energy and Smart Grid

Key concerns on petroleum proved reserves evaluation in different development stage for international cooperated assets under SEC rules

The petroleum proved reserves estimation of companies listed in American stock market must follow the SEC rules. However, there are no specified guidelines on the reserves evaluation besides the issued general regulations. This paper presents the procedures and key concerns for sub-classification of proved reserves in different development stages which are summarized from many practical cases. The important concerns include the well test data, initial well productivity, recoverable volumes assessment, five-year development workload and investment, reservoir connectivity, evaluation unit classification, historical performance identification, infill wells recognition, operating cost split, abandonment cost, etc. This study can provide a meaningful reference for SEC reserves evaluation and assets transaction in petroleum industry

Effects of Regulated Deficit Irrigation on Yield and Quality of <i>Isatis indigotica</i> in a Cold and Arid Environment

Although regulated deficit irrigation may improve crop yields, little research has been conducted on the effects of water deficits on Isatis indigotica, a popular herbal medicine. Field experiments were conducted in 2016 and 2017 to study the effects of regulated deficit irrigation on the net photosynthetic rate, yield, water use efficiency (WUE), and quality of I. indigotica in northwest China. Plants at the vegetative and fleshy root growth stages were subjected to mild, moderate, and severe water deficits, and their photosynthetic physiological indexes, yield, and WUE were measured. Moderate and severe deficits, but not a mild deficit, significantly decreased the net photosynthetic rate and dry matter accumulation. The yield and WUE under mild deficit were markedly higher, reaching 8239.56 kg·ha−2 and 8390.80 kg·ha−2, respectively, in the vegetative stage and 24.11 kg·ha−2·mm−1 and 23.62 kg·ha−2·mm−1, respectively, in the fleshy root growth stage, while severe deficits significantly reduced yield and WUE. Mild and moderate deficits increased the content of (R,S)-goitrin, indirubin, and indigo, improving root quality, but severe deficits decreased these compounds. Therefore, a mild water deficit in the vegetative and fleshy root growth stages is optimal and can reduce water consumption and improve I. indigotica quality and WUE without reducing yield

Ultrathin graphite sheets stabilized stearic acid as a composite phase change material for thermal energy storage

Ultrathin graphite sheets (UGSs) were stripped directly from natural flake graphite (FG) through a coupled ultrasonication-milling (CUM) process followed by a shear-assisted supercritical CO2 (SSC) stripping. As-prepared UGSs were centrifuged (3500 and 5000 rpm) to support stearic acid (SA) to produce SA/UGSs. Characterization results proved UGSs was stripped from natural FG. Structural and morphological characterization demonstrated that the UGS-5000 had a layer thickness was about 3.4–4.2 nm, significantly thinner than that of natural FG. Raman spectra and TG-DSC analysis showed UGS-5000 have more structural defects than other UGSs, and could accommodate a SA loading capability of 171.5%. FTIR and XRD analysis indicated that no chemical reaction had occurred between SA and UGSs during impregnation. All samples had a good thermal stability below 180 °C, with the endothermic phase change peak being recorded between 53.60 and 53.12 °C range, and the melting and freezing enthalpies of SA/UGS-5000 were 113.7 and 112.9 J g−1, respectively. After 50 thermal cycles, it could keep a great thermal reliability and has a thermal conductivity of 10.08 times higher than that of pure SA. These results demonstrate that SA/UGS-5000 have potential in thermal energy storage applications including cooling, building energy efficiency and solar thermal storage.This work was supported by the National Natural Science Foundation of China (51504041, 51874047, 51574205); the Changsha City Fund for Distinguished and Innovative Young Scholars; the Natural Science Foundation of Hunan Province (2016JJ3009); the Scientific Research Fund of Hunan Provincial Education Department (15K007); the Key Research and Development Program of Jiangxi Province (20171BBH80021); the State Key Laboratory Breeding Base of Nuclear Resources and Environment (NRE1403); the HOME Program of the Hunan Association for Science and Technology and the Hunan Province 2011 Collaborative Innovation Center of Clean Energy and Smart Grid

Study on the binding characteristics of hydroxylated polybrominated diphenyl ethers and thyroid transporters using the multispectral technique and computational simulation

<p>Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are a class of toxic environmental pollutants that are persistent, bioaccumulative, and difficult to degrade. Their structure is very similar to the thyroid hormone (T4) and uses the body’s thyroid transporter (TTR) binding to interfere with the endocrine balance, disrupting the body’s normal physiological activity. According to Fourier transform infrared spectroscopy and dynamics simulation of <i>do_dssp</i> module analysis, there are three kinds of OH-PBDEs that can induce TTR secondary structural changes. Fluorescence spectra and UV–Vis spectra show that for the three kinds of OH-PBDEs for TTR, the main methods of quenching are static quenching and non-radiative energy transfer. According to thermodynamic analysis, Δ<i>G</i> < 0, Δ<i>H</i> > 0, and Δ<i>S</i> > 0 combine to show that the hydrophobic interaction is the main driving force of the combination. From the molecular docking analysis, it was found that 4′-hydroxy-2,2′,4,5′- tetrabromodiphenyl ether (4′-OH-BDE49) and 4 hydroxy-2,2′,3,4′,5,6,6′- heptabromodiphenyl ether (4-OH-BDE188) had a cationic–π interaction with TTR, whereas 4 hydroxy-2,2′,3,4,5,5′,6- heptabromodiphenyl ether (4-OH-BDE187) was bonded to TTR by hydrogen bonds to form stable complexes. In this paper, we highlight the consistency of spectroscopic experiments and computer simulations so as to provide a reliable analytical method for the toxicological properties of small molecule contaminants.</p

Human CD1D Gene Expression Is Regulated by LEF-1 through Distal Promoter Regulatory Elements

CD1d-expressing cells present lipid Ag to CD1d-restricted NKT cells, which play an important role in immune regulation and tumor rejection. Lymphoid enhancer-binding factor-1 (LEF-1) is one of the regulators of the Wnt signaling pathway, which is a powerful regulator in cellular growth, differentiation, and transformation. There is little evidence connecting Wnt signaling to CD1d expression. In this study, we have identified LEF-1 as a regulator of the expression of the gene encoding the human CD1d molecule (CD1D). We found that LEF-1 binds specifically to the CD1D promoter. Overexpression of LEF-1 in K562 or Jurkat cells suppresses CD1D promoter activity and downregulates endogenous CD1D transcripts, whereas knockdown of LEF-1 using LEF-1 specific small interfering RNA increases CD1D transcripts in K562 and Jurkat cells but there are different levels of surface CD1d on these two cell types. Chromatin immunoprecipitation showed that the endogenous LEF-1 is situated at the CD1D promoter and interacts with histone deacetylase-1 to facilitate the transcriptional repressor activity. Knockdown of LEF-1 using small interfering RNA potentiates an acetylation state of histone H3/H4, supporting the notion that LEF-1 acts as a transcriptional repressor for the CD1D gene. Our finding links LEF-1 to CD1D and suggests a role of Wnt signaling in the regulation of the human CD1D gene. The Journal of Immunology, 2010, 184: 5047-5054