39 research outputs found
In Situ Synthesis of Monodisperse Silver Nanoparticles on Sulfhydryl-Functionalized Poly(glycidyl methacrylate) Microspheres for Catalytic Reduction of 4‑Nitrophenol
Immobilization
of silver nanoparticles (Ag NPs) to improve monodispersity
and recyclability is crucial for applications in nanocatalysts. Herein,
a novel protocol for stabilizer-free, effective, and in situ synthesis
of Ag NPs on sulfhydryl-functionalized polyÂ(glycidyl methacrylate)
microspheres (PGMA-SH) was proposed. Ag NPs of 16.97 ± 3.15 nm
were successfully grown on PGMA-SH, and remained monodisperse and
stable even after sonication, washing, and long-term storage. Moreover,
the Ag NPs on PGMA-SH (Ag NPs@PGMA-SH) composite exhibited excellent
catalytic activity with an average normalized activity parameter of
4.38 × 10<sup>–3</sup> L·mg<sup>–1</sup>·s<sup>–1</sup> toward the reduction of 4-nitrophenol, which was
1.3–132 times higher than reported in literature. The composite
can be easily recycled and showed excellent reusability as a conversion
higher than 92% was achieved after 10 cycles. Thus, the preparation
of Ag NPs@PGMA-SH has been proven a feasible, straightforward, and
effective protocol, which would facilitate the applications of Ag
NPs in environmental control
Fabrication of High Efficient Silver Nanoparticle Catalyst Supported on Poly(glycidyl methacrylate)–Polyacrylamide
Fabrication of highly efficient silver
nanoparticle (Ag NP) catalysts
supported on polyacrylamide (PAM)-modified polyÂ(glycidyl methacrylate)
(PGMA) microspheres was reported herein, for where PAM was used as
the robust anchors because of its abundant amide groups. Well-dispersed
Ag NPs with an average diameter of 9.7 nm were obtained on the PGMA–PAM
microspheres (Ag NPs@PGMA–PAM). Excellent catalytic activity
of Ag NPs@PGMA–PAM was observed in the reduction of 4-nitrophenol
using sodium borohydride in water at room temperature, indicated by
an activity parameter that was 6–1725 times higher than those
reported in the literature. In addition, easy regulation on the size
of Ag NPs was achieved through the adjustment on the concentration
of the Ag precursor, AgNO<sub>3</sub>. Therefore, the synthetic method
proposed herein was confirmed as being effective for the synthesis
of the highly efficient catalyst Ag NPs@PGMA–PAM. This would
contribute to the preparation of highly efficient catalyst of supported
noble metals and then facilitate their applications in environmental
protection
DataSheet_1_The association between blood heavy metals level and sex hormones among postmenopausal women in the US.docx
IntroductionEnvironmental pollutants could be implicated in female endocrine setting Q6 beyond traditional factors. Until now, few study has focused on the association of environmental exposure to heavy metals with sex hormones in postmenopausal women. This study intended to investigate whether serum levels of heavy metals(i.e., Cd, Pb, Hg, Mn, Se) would influence sex hormones in postmenopausal women.Methods and resultsA cross-sectional study was performed on 614 nationally representative participants from 2013-2016 National Health and Nutrition Examination Survey (NHANES) in the US. Multivariate linear regression models and restricted cubic spline plots revealed cadmium(Cd) had linear positive association with TT(β=3.25, 95%CI= 1.12, 5.38), bioavailable TT(β=1.78, 95%CI=0.36,3.21) and TT/E2(β=0.76, 95%CI=0.28,1.24), which was more apparent in natural menopausal and obese women. Lead(Pb) had linear positive association with SHBG(β=12.84, 95%CI= 6.77,18.91), which was apparent in nearly all subgroups except in normal BMI group, and TT/E2 (β=0.69, 95%CI 0.134,1.25), which was apparent in natural menopausal and normal BMI women. Manganese(Mn) had non-linear association with SHBG, which was more apparent in natural menopausal and obese women, and TT/E2, which was more apparent in natural menopausal and normal BMI women. Selenium(Se) had U shaped non-linear association with TT, which was more apparent in hysterectomy, overweight and obese women, and SHBG, which was apparent in nearly all subgroups except in normal BMI group.ConclusionIn summary, this cross-sectional study indicates a possible role that various degree of environmental exposure to heavy metals plays in the disruption of sex Q5 hormone levels in postmenopausal women. Further experiments are needed to elucidate the underlying mechanisms.</p
PEPIS: A Pipeline for Estimating Epistatic Effects in Quantitative Trait Locus Mapping and Genome-Wide Association Studies
<div><p>The term epistasis refers to interactions between multiple genetic loci. Genetic epistasis is important in regulating biological function and is considered to explain part of the ‘missing heritability,’ which involves marginal genetic effects that cannot be accounted for in genome-wide association studies. Thus, the study of epistasis is of great interest to geneticists. However, estimating epistatic effects for quantitative traits is challenging due to the large number of interaction effects that must be estimated, thus significantly increasing computing demands. Here, we present a new web server-based tool, the Pipeline for estimating EPIStatic genetic effects (PEPIS), for analyzing polygenic epistatic effects. The PEPIS software package is based on a new linear mixed model that has been used to predict the performance of hybrid rice. The PEPIS includes two main sub-pipelines: the first for kinship matrix calculation, and the second for polygenic component analyses and genome scanning for main and epistatic effects. To accommodate the demand for high-performance computation, the PEPIS utilizes C/C++ for mathematical matrix computing. In addition, the modules for kinship matrix calculations and main and epistatic-effect genome scanning employ parallel computing technology that effectively utilizes multiple computer nodes across our networked cluster, thus significantly improving the computational speed. For example, when analyzing the same immortalized F2 rice population genotypic data examined in a previous study, the PEPIS returned identical results at each analysis step with the original prototype R code, but the computational time was reduced from more than one month to about five minutes. These advances will help overcome the bottleneck frequently encountered in genome wide epistatic genetic effect analysis and enable accommodation of the high computational demand. The PEPIS is publically available at <a href="http://bioinfo.noble.org/PolyGenic_QTL/" target="_blank">http://bioinfo.noble.org/PolyGenic_QTL/</a>.</p></div
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation
Summary of parallel strategy in the PEPIS for increasing analysis speed.
<p>Summary of parallel strategy in the PEPIS for increasing analysis speed.</p
In Situ Real-Time Study on Dynamics of Microbially Induced Calcium Carbonate Precipitation at a Single-Cell Level
Ureolytic
microbially induced calcium carbonate precipitation (MICP) is a promising
green technique for addressing a variety of environmental and architectural
concerns. However, the dynamics of MICP especially at the microscopic
level remains relatively unexplored. In this work, by applying a bacterial
tracking technique, the growth dynamics of micrometer-sized calcium
carbonate precipitates induced by <i>Sporosarcina pasteurii</i> were studied at a single-cell resolution. The growth of micrometer-scale
precipitates and the occurrence and dissolution of many unstable submicrometer
calcium carbonate particles were observed in the precipitation process.
More interestingly, we observed that micrometer-sized precipitated
crystals did not grow on negatively charged cell surfaces nor on other
tested polystyrene microspheres with different negatively charged
surface modifications, indicating that a negatively charged surface
was not a sufficient property for nucleating the growth of precipitates
in the MICP process under the conditions used in this study. Our observations
imply that the frequently cited model of bacterial cell surfaces as
nucleation sites for precipitates during MICP is oversimplified. In
addition, additional growth of calcium carbonates was observed on
old precipitates collected from previous runs. The presence of bacterial
cells was also shown to affect both morphologies and crystalline structures
of precipitates, and both calcite and vaterite precipitates were found
when cells physically coexisted with precipitates. This study provides
new insights into the regulation of MICP through dynamic control of
precipitation