The magnitude of the volume change in response to changes in the water content is usually described by the soil-shrinkage characteristic curve (SSCC). The void ratio of soil is affected by its ...shrinkage behavior, and the soil water characteristic curve (SWCC) will be affected. In this paper, a new test platform is introduced to measure the soil shrinkage behavior during the drying process of silicon micropowder (SMP), Guangxi Guiping clay (GGC) and kaolin. The soil water characteristic curves of these tested soils were measured without and with considering volume change during soil shrinking. The results show that after drying ended, the volume shrinkage values of the soil samples were 0.31%, 20.1% and 31.4%, while the corresponding initial void ratios were 0.67, 1.03, and 1.04, respectively. The soil shrinkage curve with decreasing water content could be divided into three stages: normal shrinkage, residual shrinkage and zero shrinkage. In addition, the void ratio after soil shrinkage had a considerable influence on the SWCC.
•This paper proposed a new method for measuring the shrinkage and deformation of soil samples.•The soil water characteristic curves are measured without and with considering volume change during soil shrinking.•The void ratio after soil shrinkage had a considerable influence on the SWCC.
Multidimensional nano‐heterostructures (NHSs) that have unique dimensionality‐dependent integrative and synergic effects are intriguing but still underdeveloped. Here, we report the first helical ...1D/2D epitaxial NHS between CdS and ZnIn2S4. Experimental and theoretical studies reveal that the mismatches in lattice and dangling bonds between 1D and 2D units govern the growth procedure. The resulting well‐defined interface induces the delocalized interface states, thus facilitate the charge transfer and enhance the performance in the photoelectrochemical cells. We foresee that the mechanistic insights gained and the electronic structures revealed would inspire the design of more complex 1D/2D NHSs with outstanding functionalities.
Rotate and connect! The shape evolution of a helical 1D/2D semiconductor nano‐heterostructure (NHS) consisting of CdS and ZnIn2S4 is demonstrated. This NHS exhibits enhanced performance in photoelectrochemical cells, which is explained by the interface electronic states and the tailored band alignment.
This paper develops a concentration retrieval technique based on the particle swarm optimization (PSO) algorithm, which is used for a calibration-free wavelength modulation spectroscopy system. As ...compared with the commonly used technique based on the Levenberg-Marquardt (LM) algorithm, the PSO-based method is less dependent on the pre-characterization of the laser tuning parameters. We analyzed the key parameters affecting the performance of the PSO-based technique and determined their optimal parameter values through testing. Furthermore, we conducted a comparative analysis of the efficacy of two techniques in detecting C
H
concentration. The results showed that the PSO-based concentration retrieval technique is about 63 times faster than the LM-based one in achieving the same accuracy. Within 5 s, the PSO-based technique can produce findings that are generally consistent with the values anticipated.
Photoelectrochemical (PEC) technology for the conversion of solar energy into chemicals requires cost‐effective photoelectrodes to efficiently and stably drive anodic and/or cathodic half‐reactions ...to complete the overall reactions for storing solar energy in chemical bonds. The shared properties among semiconducting photoelectrodes and photovoltaic (PV) materials are light absorption, charge separation, and charge transfer. Earth‐abundant silicon materials have been widely applied in the PV industry, and have demonstrated their efficiency as alternative photoabsorbers for photoelectrodes. Many efforts have been made to fabricate silicon photoelectrodes with enhanced performance, and significant progress has been achieved in recent years. Herein, recent developments in crystalline and thin‐film silicon‐based photoelectrodes (including amorphous, microcrystalline, and nanocrystalline silicon) immersed in aqueous solution for PEC hydrogen production from water splitting are summarized, as well as applications in PEC CO2 reduction and PEC regeneration of discharged species in redox flow batteries. Silicon is an ideal material for the cost‐effective production of solar chemicals through PEC methods.
Capturing sunlight: Photoelectrochemical (PEC) conversion of solar energy to chemicals requires cost‐effective and durable photoelectrodes. Silicon is a promising candidate material as a photoabsorber for efficient photoanodes and ‐cathodes due to its variety of crystal structures, customizable morphology, and controllable conductivity. In this review, recent developments of crystalline and thin‐film silicon‐based photoelectrodes immersed in aqueous solution for the solar PEC production of chemicals are summarized.
Active pointing compensation of a High Throughput Satellite (HTS) multibeam antenna via microfiber composites (MFCs) is studied in this paper. Electrical-mechanical coupling analysis of MFCs is ...conducted to quantitatively determine driving forces and moments of MFCs attached on a carbon fiber reinforced composite (CFRP) laminate, and a positive correlation relationship is observed for driving ability versus thickness of the laminate. By different driving strategies, MFCs could act in bending mode and torsioning mode for structural deformation control, and driving efficiency of the MFCs on a multibeam antenna is studied. Thermal distortion of the antenna under a typical in orbit thermal distribution causes the reflector to rotate about y axis with an pointing error of 0.005°, active compensation is conducted, and the final compensation results show that with an optimal voltage of 432 V, pointing error of the antenna is greatly compensated, and the depointing angle is corrected to be 0.00004°.
In the rumen bacteria, ammonia as the end product of nitrogen is incorporated into carbon skeleton (α-ketoglutarate) to yield glutamine and glutamate which are important nitrogen donors in ...nitrogenous compounds metabolism in cells. The enzymes glutamine synthetase, glutamate synthetase, and glutamate dehydrogenase are involved in these processes. Some experimental results have proven that the global nitrogen regulation system may participate in the regulation of assimilation of ammonia in rumen bacteria. This review offers a current perspective on the pathways and key enzymes of ammonia assimilation in rumen bacteria with the possible molecular regulation strategy, while points out the further research direction.
It is well-known that silica can be etched in alkaline media or in a unique hydrofluoric acid (HF) solution, which is widely used to prepare various kinds of hollow nanostructures (including silica ...hollow structures) via silica-templating methods. In our experiments, we found that stöber silica spheres could be etched in generic acidic media in a well-controlled way under hydrothermal conditions, forming well-defined hollow/rattle-type silica spheres. Furthermore, some salts such as NaCl and Na(2)SO(4) were found to be favorable for the formation of hollow/rattle-type silica spheres.
Uniform Pt−Cu alloy nanocrystals in the shape of dendrite, yolk‐cage, and box structures are prepared via a facile wet‐chemical reduction route in which glycine is demonstrated to alter the reduction ...kinetics of metal cations, critical to the morphology of the obtained product. These alloy nanocrystals exhibit superior specific activity and stability in the electro‐oxidation of methanol.
•Prenatal PM2.5 exposure was associated with reduced fetal growth.•Prenatal PM2.5 exposure could lead to aberrant changes in DNA methylation profile of placenta genome.•Methylation in BID (BH3 ...interacting domain death agonist) partially mediated the effects of PM2.5 exposure on fetal growth.•Prenatal PM2.5 exposure might disrupt fetal growth by affecting placental DNA methylation.
This study was designed to examine the impact of prenatal fine particulate matter (PM2.5) exposure on fetal growth and the underlying placental epigenetic mechanism in a cohort of Chinese women. Within the prospective Shanghai Mother-Child Pairs cohort (Shanghai MCPC), 329 women carrying singleton pregnancy with a due date in 2018 were recruited between 2017 and 2018. Maternal PM2.5 exposure levels were estimated using gestational exposure prediction model combining satellite-driven ambient concentrations and personal air sampling. Fetal growth characteristics were evaluated by prenatal ultrasound examinations and anthropometric measurements at birth. In a discovery phase, whole-genome DNA methylation analysis was performed using the Infinium 850 K array. In a validation phase, placental DNA methylation was measured using bisulfite pyrosequencing for five candidate genes that showed the most significant alterations and function relevance in our methylation array screen, including BID (BH3 interacting domain death agonist), FOXN3 (Forkhead box N3), FOXP1 (Forkhead box P1), IGF2 (Insulin-like growth factor 2) and HSD11B2 (Hydroxysteroid 11-beta dehydrogenase 2). Multivariate linear regression models were applied to examine the associations among PM2.5 exposure, fetal growth characteristics and DNA methylation on placental candidate genes. Sobel tests were used to evaluate the mediating role of DNA methylation in multivariable models. After excluding women who withdrew or failed to provide placenta, a total of 287 pregnant women with an average age of 30 entered the final analysis. Increased PM2.5 exposure was significantly associated with reduced biparietal diameter (BPD) (β: −0.136 mm, 95% CI: −0.228 to −0.043), head circumference (HC) (β: −0.462 mm, 95% CI: −0.782 to −0.142), femur length (FL) (β: −0.113 mm, 95% CI: −0.185 to −0.041) and abdominal circumference (AC) (β: −0.371 mm, 95% CI: −0.672 to −0.071) in the second trimester and birth length (β: −0.013 cm, 95% CI: −0.025 to −0.001). Prenatal PM2.5 exposure could lead to aberrant changes in DNA methylation profile of placenta genome, which were mainly enriched in reproductive development, energy metabolism and immune response. DNA methylation of IGF2 and BID showed significant associations with PM2.5 exposures during all exposure windows. In addition, BID methylation was negatively correlated with HC (β: −1.396 mm, 95% CI: −2.582 to −0.209) and BPD (β: −0.330 mm, 95% CI: −0.635 to −0.026) in the second trimester. Further mediation analysis indicated that BID methylation mediated about 30% of the effects of PM2.5 exposure on HC. These findings collectively suggested that prenatal PM2.5 exposure may cause adverse effects on fetal growth by modifying placental DNA methylation.
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