298 research outputs found
Modulating Carrier Kinetics in BiVO4 Photoanodes through Molecular Co4O4 Cubane Layers
Understanding the role and immobilization of molecular catalysts on photoelectrodes is essential to use their full potential for efficient solar fuel generation. Here, a CoII4O4 cubane with proven catalytic performance and an active H2OâCo2(OR)2âOH2 edge-site moiety is immobilized on BiVO4 photoanodes through a versatile layer-by-layer assembly strategy. This delivers a photocurrent of 3.3 mA cmâ2 at 1.23 VRHE and prolonged stability. Tuning the thickness of the Co4O4 layer has remarkable effects on photocurrents, dynamic open circuit potentials, and charge carrier behavior. Comprehensive-time and frequency-dependent perturbation techniques are employed to investigate carrier kinetics in transient and pseudo-steady-state operando conditions. It is revealed that the Co4O4 layer can prolong carrier lifetime, unblock kinetic limitations at the interface by suppressing recombination, and enhance charge transfer. Additionally, its flexible roles are identified as passivation/hole trapping/catalytic layer at respective lower/moderate/higher potentials. These competing functions are under dynamic equilibrium, which fundamentally defines the observed photocurrent trends
Dynamics and control of active sites in hierarchically nanostructured cobalt phosphide/chalcogenide-based electrocatalysts for water splitting
The rational design of efficient electrocatalysts for industrial water splitting is essential to generate sustainable hydrogen fuel. However, a comprehensive understanding of the complex catalytic mechanisms under harsh reaction conditions remains a major challenge. We apply a self-templated strategy to introduce hierarchically nanostructured âall-surfaceâ Fe-doped cobalt phosphide nanoboxes (Co@CoFeâP NBs) as alternative electrocatalysts for industrial-scale applications. Operando Raman spectroscopy and X-ray absorption spectroscopy (XAS) experiments were carried out to track the dynamics of their structural reconstruction and the real catalytically active intermediates during water splitting. Our operando analyses reveal that partial Fe substitution in cobalt phosphides promotes a structural reconstruction into PâCoâOâFeâP configurations with low-valence metal centers (M0/M+) during the hydrogen evolution reaction (HER). Results from density functional theory (DFT) demonstrate that these in situ reconstructed configurations significantly enhance the HER performance by lowering the energy barrier for water dissociation and by facilitating the adsorption/desorption of HER intermediates (H*). The competitive activity in the oxygen evolution reaction (OER) arises from the transformation of the reconstructed PâCoâOâFeâP configurations into oxygen-bridged, high-valence CoIVâOâFeIV moieties as true active intermediates. In sharp contrast, the formation of such CoIII/IVâOâFeIII/IV moieties in CoâFeOOH is hindered under the same conditions, which outlines the key advantages of phosphide-based electrocatalysts. Ex situ studies of the as-synthesized reference cobalt sulfides (CoâS), Fe doped cobalt selenides (Co@CoFeâSe), and Fe doped cobalt tellurides (Co@CoFeâTe) further corroborate the observed structural transformations. These insights are vital to systematically exploit the intrinsic catalytic mechanisms of non-oxide, low-cost, and robust overall water splitting electrocatalysts for future energy conversion and storage
Determinants of ageâappropriate breastfeeding, dietary diversity, and consumption of animal source foods among Indonesian children
Global child feeding practices remain suboptimal. In this study, we assess the determinants of ageâinappropriate breastfeeding, dietary diversity, and consumption of
3+ types of animal source foods (ASFs) using 11,687 observations from combined
data from the Indonesian Demographic Health Survey of 2012 and 2017. We used
linear and logistic regression after adjusting for the complex sampling design. Child's
age and quality of antenatal care (ANC) were associated with all outcomes. Socioâ
economic status and labour force participation were positively associated with higher
dietary diversity score, ASF consumption, and ageâinappropriate breastfeeding. More
ANC visits and having consultation at ANC were associated with more dietary diversity. Higher women's knowledge level was associated with more dietary diversity and
consuming more ASF. Compared with western Indonesia, more children in eastern
Indonesia were ageâinappropriately breastfed and had lower dietary diversity. The
Indonesian government needs to develop programmes to improve child feeding particularly in eastern Indonesia, focusing on improving dietary diversity and ASF consumption in poorer households and on prolonging breastfeeding in richer
households. Women's labour force participation should be encouraged, but
programmes for working mothers are also needed to support continued breastfeeding
and to express breast milk. ANC and postnatal programmes need improved consultation sessions for child feeding.
KEYWORDS
breastfeeding, dietary diversity, animal source food, child feeding, Indonesi
Determinants of ageâappropriate breastfeeding, dietary diversity, and consumption of animal source foods among Indonesian children
Global child feeding practices remain suboptimal. In this study, we assess the determinants of ageâinappropriate breastfeeding, dietary diversity, and consumption of
3+ types of animal source foods (ASFs) using 11,687 observations from combined
data from the Indonesian Demographic Health Survey of 2012 and 2017. We used
linear and logistic regression after adjusting for the complex sampling design. Child's
age and quality of antenatal care (ANC) were associated with all outcomes. Socioâ
economic status and labour force participation were positively associated with higher
dietary diversity score, ASF consumption, and ageâinappropriate breastfeeding. More
ANC visits and having consultation at ANC were associated with more dietary diversity. Higher women's knowledge level was associated with more dietary diversity and
consuming more ASF. Compared with western Indonesia, more children in eastern
Indonesia were ageâinappropriately breastfed and had lower dietary diversity. The
Indonesian government needs to develop programmes to improve child feeding particularly in eastern Indonesia, focusing on improving dietary diversity and ASF consumption in poorer households and on prolonging breastfeeding in richer
households. Women's labour force participation should be encouraged, but
programmes for working mothers are also needed to support continued breastfeeding
and to express breast milk. ANC and postnatal programmes need improved consultation sessions for child feeding
Age-related terminal duct lobular unit involution in benign tissues from Chinese breast cancer patients with luminal and triple-negative tumors
Abstract Background Terminal duct lobular unit (TDLU) involution is a physiological process of breast tissue aging characterized by a reduction in the epithelial component. In studies of women with benign breast disease, researchers have found that age-matched women with lower levels of TDLU involution are at increased risk of developing breast cancer. We previously showed that breast cancer cases with core basal phenotype (CBP; estrogen receptor negative [ERâ], progesterone receptor-negative [PRâ], human epidermal growth factor receptor 2-negative [HER2â], cytokeratins (CK 5 or CK5/6)-positive [CK5/6+] and/or epidermal growth factor receptor-positive [EGFR+]) tumors had significantly reduced TDLU involution compared with cases with luminal A (ER+ and/or PR+, HER2â, CK5/6â, EGFRâ) tumors from a population-based case-control study in Poland. We evaluated the association of TDLU involution with tumor subtypes in an independent population of women in China, where the breast cancer incidence rate, prevalence of known risk factors, and mammographic breast density are thought to be markedly different from those of Polish women. Methods We performed morphometric assessment of TDLUs by using three reproducible semiquantitative measures that inversely correlate with TDLU involution (TDLU count/100Â mm2, TDLU span in micrometer, and acini count/TDLU) by examining benign tissue blocks from 254 age-matched luminal A and 250 triple-negative (TN; ERâ, PRâ, HER2â, including 125 CBP) breast cancer cases treated in a tertiary hospital in Beijing, China. Results Overall, we found that TN and particularly CBP cases tended to have greater TDLU measures (less involution) than luminal A cases in logistic regression models accounting for age, body mass index, parity, and tumor grade. The strongest association was observed for tertiles of acini count among younger women (aged <50Â years) (CBP vs. luminal A; ORtrend 2.11, 95% CI 1.22â3.67, Pâ=â0.008). Conclusions These data extend previous findings that TN/CBP breast cancers are associated with reduced TDLU involution in surrounding breast parenchyma compared with luminal A cases among Chinese women, providing further support for differences in the pathogenesis of these tumor subtypes
The small RNA SgrS controls sugarâphosphate accumulation by regulating multiple PTS genes
A number of bacterial small RNAs (sRNAs) act as global regulators of stress responses by controlling expression of multiple genes. The sRNA SgrS is expressed in response to glucoseâphosphate stress, a condition associated with disruption of glycolytic flux and accumulation of sugarâphosphates. SgrS has been shown to stimulate degradation of the ptsG mRNA, encoding the major glucose transporter. This study demonstrates that SgrS regulates the genes encoding the mannose and secondary glucose transporter, manXYZ. Analysis of manXYZ mRNA stability and translation in the presence and absence of SgrS indicate that manXYZ is regulated by SgrS under stress conditions and when SgrS is ectopically expressed. In vitro footprinting and in vivo mutational analyses showed that SgrS base pairs with manXYZ within the manX coding sequence to prevent manX translation. Regulation of manX did not require the RNase E degradosome complex, suggesting that the primary mechanism of regulation is translational. An Escherichia coli ptsG mutant strain that is manXYZ+ experiences stress when exposed to the glucose analogs α-methyl glucoside or 2-deoxyglucose. A ptsG manXYZ double mutant is resistant to the stress, indicating that PTS transporters encoded by both SgrS targets are involved in taking up substrates that cause stress
Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets
This document is the Technical Design Report covering the two large
spectrometer magnets of the PANDA detector set-up. It shows the conceptual
design of the magnets and their anticipated performance. It precedes the tender
and procurement of the magnets and, hence, is subject to possible modifications
arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti
Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski,
Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy),
Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy
Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR
Simulation results for future measurements of electromagnetic proton form
factors at \PANDA (FAIR) within the PandaRoot software framework are reported.
The statistical precision with which the proton form factors can be determined
is estimated. The signal channel is studied on the basis
of two different but consistent procedures. The suppression of the main
background channel, , is studied.
Furthermore, the background versus signal efficiency, statistical and
systematical uncertainties on the extracted proton form factors are evaluated
using two different procedures. The results are consistent with those of a
previous simulation study using an older, simplified framework. However, a
slightly better precision is achieved in the PandaRoot study in a large range
of momentum transfer, assuming the nominal beam conditions and detector
performance
The application of Graphene as a sample support in Transmission Electron Microscopy
Transmission electron microscopy has witnessed rampant development and
surging point resolution over the past few years. The improved imaging
performance of modern electron microscopes shifts the bottleneck for image
contrast and resolution to sample preparation. Hence, it is increasingly being
realized that the full potential of electron microscopy will only be realized
with the optimization of current sample preparation techniques. Perhaps the
most recognized issues are background signal and noise contributed by sample
supports, sample charging and instability. Graphene provides supports of single
atom thickness, extreme physical stability, periodic structure, and ballistic
electrical conductivity. As an increasing number of applications adapting
graphene to their benefit emerge, we discuss the unique capabilities afforded
by the use of graphene as a sample support for electron microscopy.Comment: Review, to appear in solid state communication
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