Abstract
Tuning metal–support interaction has been considered as an effective approach to modulate the electronic structure and catalytic activity of supported metal catalysts. At the atomic level, ...the understanding of the structure–activity relationship still remains obscure in heterogeneous catalysis, such as the conversion of water (alkaline) or hydronium ions (acid) to hydrogen (hydrogen evolution reaction, HER). Here, we reveal that the fine control over the oxidation states of single-atom Pt catalysts through electronic metal–support interaction significantly modulates the catalytic activities in either acidic or alkaline HER. Combined with detailed spectroscopic and electrochemical characterizations, the structure–activity relationship is established by correlating the acidic/alkaline HER activity with the average oxidation state of single-atom Pt and the Pt–H/Pt–OH interaction. This study sheds light on the atomic-level mechanistic understanding of acidic and alkaline HER, and further provides guidelines for the rational design of high-performance single-atom catalysts.
The conversion of solar energy into electricity is a viable response to address most of world's energy problems. Among the parameters affecting the performance of both photovoltaic (PV) cells and ...concentrating solar power (CSP) systems include their orientation and tilt angle with respect to the sun. Solar trackers (ST) are ideal devises for efficiency improvement. This paper aims to review the most commonly used ST and identify the systems that offer benefits such as greater efficiency, greater tracking accuracy, easy installation and cost effectiveness.
There are mainly two types of ST viz. single and double axis ST. The optimization of these devices requires cumbersome specifications to avoid potential tracking errors that often lead to their poor performance. These specifications cannot be fulfilled by simple tracking methods due to different sources of tracking errors such as the misalignment of the tracking fixture, the level of pollution of the area, the shading of the sensors, the types of control schemes involved, the auxiliary units of the system, the lack of maintenance as well as the imperfection and power mismatch of connecting grids.
The study reveals that double axis ST in form of polar-axis and azimuth/elevation featuring the solar movement models and the dynamic closed loop feedback control are the most effective and generally give more than a 40% improvement in energy return compared to fixed PV panels. Moreover, large systems significantly reduce the costs and save on materials. The energy consumed by the moving fixtures is mostly low (2–5% of the collected energy) but this could be higher if no optimization is performed. Lastly, all the hardware and software energy saving parameters must be optimized right from the early stages of the development of the system to prevent materials wastage and the energy over-consumption by the tracking units.
Recent years have witnessed rapid progress in the field of epitranscriptomics. Functional interpretation of the epitranscriptome relies on sequencing technologies that determine the location and ...stoichiometry of various RNA modifications. However, contradictory results have been reported among studies, bringing the biological impacts of certain RNA modifications into doubt. Here, we develop a synthetic RNA library resembling the endogenous transcriptome but without any RNA modification. By incorporating this modification-free RNA library into established mapping techniques as a negative control, we reveal abundant false positives resulting from sequence bias or RNA structure. After calibration, precise and quantitative mapping expands the understanding of two representative modification types, N
-methyladenosine (m
A) and 5-methylcytosine (m
C). We propose that this approach provides a systematic solution for the calibration of various RNA-modification mappings and holds great promise in epitranscriptomic studies.
Cell membrane–based nanosystems with desirable characteristics have been studied extensively for many therapeutic applications. However, current research has focused on single cell membrane, and ...multifunctional fused membrane materials from different membrane types are still rare. Herein, a platelet–cancer stem cell (CSC) hybrid membrane‐coated iron oxide magnetic nanoparticle (MN) {CSC‐PMN} is presented for the first time for the enhanced photothermal therapy of head and neck squamous cell carcinoma (HNSCC). Inherited from the original source cells, the platelet membrane shows immune evading ability due to the surface marker comprising a number of “don't eat me” signals, and the CSC membrane has homotypic targeting capabilities due to the specific surface adhesion molecules. The CSC‐PMNs possess superior characteristics for immune evasion, active cancer targeting, magnetic resonance imaging, and photothermal therapy. Compared with single cell membrane–coated MNs, CSC‐PMNs exhibit prolonged circulation times and enhanced targeting abilities. Moreover, the CSC‐PMNs exhibit a superior photothermal ability that provides excellent HNSCC tumor growth inhibition, particularly in an immunocompetent Tgfbr1/Pten conditional double knockout HNSCC mouse model that contains a more complex tumor microenvironment that is similar to the human HNSCC microenvironment. Collectively, this biomimetic multimembrane‐coated nanoplatform may provide enhanced antitumor efficacy in the complex tumor microenvironment.
A natural cancer stem cell‐platelet hybrid mimic membrane is collected from tumor‐bearing mice and further used for magnetic nanoparticle coating. The obtained biomimetic nanoparticles are then injected into the same mice for magnetic resonance imaging and photothermal therapy. The work presents a novel design strategy for personalized cancer theranostics.
Monolayer antimonene is fabricated on PdTe2 by an epitaxial method. Monolayer antimonene is theoretically predicted to have a large bandgap for nanoelectronic devices. Air‐exposure experiments ...indicate amazing chemical stability, which is great for device fabrication. A method to fabricate high‐quality monolayer antimonene with several great properties for novel electronic and optoelectronic applications is provided.
•Biochar reduced runoff volumes and ratios of slopping land.•Biochar decreased the concentrations of N and P in the runoff.•Biochar has induced significant reduction of the nutrients losses.•Biochar ...exhibits a risk of increasing sediment loss under tillage conditions.
The effects of biochar on runoff and loss of soil and nutrients in the subtropical regions of China are rarely documented. Two field experiments, an orchard and a cropland field were set up, involving two treatments: biochar (BC) and no-biochar (NBC). The effects of BC on runoff volumes and ratios, sediment yield and the level of nutrient losses were monitored and evaluated over three years (2014–2016). Results showed that the treatment of BC induced a significant reduction in the runoff and nutrients losses. By plotting the data collected for the BC application, we observed that the average annual runoff decreased by 19–28%, whereas the average annual sediment yield by 11%. The cumulative values of total nitrogen (N) and phosphorus (P) losses were also substantially minimized by the BC treatment compared with the NBC one (P<0.05). However, the average annual concentrations of total N and P losses as obtained from the BC plots (16.21mgL−1 and 0.72–0.99mgL−1) were still high, and exceeding the wastewater discharge standard (N: 15mgL−1 and P: 0.5mgL−1). In addition, under tillage conditions, the BC application led to larger sediments yield (6.5gm−2) in contrast with the NBC treatment (5.5gm−2). In general, these findings can suggest that BC exhibits a vital efficiency in the control of soil erosion process, but there is a risk of increasing sediment loss under tillage conditions, which might need to be made up by combined with biological and agronomic managements such as straw mulching or adding polyacrylamide into soil in order to control further soil erosion.
•Bamboo biochar markedly succeed to improve soil properties.•Biochar significantly decreased the availability of Cd in acid soils.•Biochar enhanced the growth of cabbage and maize ...plants.•Accumulation of Cd strongly decreased in 1.5% biochar treated soil.•Biochar had an important role in eco-restoration of Cd polluted soils.
Biochar is an organic amendment with good effects on soil properties but its influence on Cd fractionation and growth of vegetable crops (e.g. Chinese cabbage) and field crops (e.g. maize) is still restricted. A pot experiment was conducted to investigate the effect of biochar derived from bamboo residues (pyrolyzed at temperature of 400°C) at four levels (0%, 0.5%, 1% and 1.5%) on Cd solubility and bioavailability, and plant growth in a loamy soil artificially contaminated with Cd at three rates (0, 5 and 50mgkg−1). The soil was strongly acidic (pH=4.63) with low organic carbon content (1.064gkg−1). Chinese cabbage and maize were used as indicator plants in this investigation. Addition of babmboo biochar significantly increased soil pH, electrical conductivity (EC), organic carbon (SOC), and cation exchange capacity (CEC). Concentrations of Cd in CaCl2 and DTPA extractions decreased due to the increase of biochar rates but there were no alterations noticed in total concentrations of Cd in the soil. The acid soluble/exchangeable Cd decreased by 3.35–3.88 times, but the reducible and oxidizable fractions of Cd increased by 1.95–1.96 times and 1.91–2.14 times, respectively, after harvesting cabbage and maize plants in the presence of 1.5% biochar. Changes of soil properties, especially pH could be used as a good reason to illustrate the immobilization of Cd in biochar treated soils. The increase of biochar rates from 0% to 1.5% enhanced the growth of cabbage by 64.23%, 47.31% and 34.93%, and maize by 50.78%, 32.83% and 29.68% in soils treated with Cd at 0, 5 and 50mgkg−1, respectively. Using biochar at a dose of 1.5% diminished concentrations of Cd in cabbage shoots by 4.71–2.29 times and in maize shoots by 5.17–2.68 times, respectively. Our results suggested that bamboo biochar had positive residual effects on maize after the harvest of cabbage. Finally, bamboo biochar, especially at its highest rate (1.5%) could be recommended as a safe amendment in the immobilization of Cd in contaminated agricultural soils and then reduced its threat on the food chain and human health.
By inducing a Raman transition using a pair of Gaussian and Laguerre-Gaussian laser beams, we realize a ^{87}Rb condensate whose orbital angular momentum (OAM) and its internal spin states are ...coupled. By varying the detuning and the coupling strength of the Raman transition, we experimentally map out the ground-state phase diagram of the system for the first time. The transitions between different phases feature a discontinuous jump of the OAM and the spin polarization, and hence are of first order. We demonstrate the hysteresis loop associated with such first-order phase transitions. The role of interatomic interaction is also elucidated. Our work paves the way to explore exotic quantum phases in the spin-orbital-angular-momentum coupled quantum gases.
Transition metal catalyzed decarbonylation offers a distinct synthetic strategy for new chemical bond formation. However, the π‐backbonding between CO π* orbitals and metal center d‐orbitals impedes ...ligand dissociation to regenerate the catalyst under mild reaction conditions. Developed here is visible light induced rhodium catalysis for decarbonylative coupling of imides with alkynes under ambient conditions. Initial mechanistic studies suggest that the rhodium complex simultaneously serves as the catalytic center and photosensitizer for decarbonylation. This visible light promoted catalytic decarbonylation strategy offers new opportunities for reviewing old transformations with ligand dissociation as a rate‐determining step.
Visible light induced rhodium catalysis has been developed for decarbonylative coupling of imides with alkynes under ambient conditions. Initial mechanistic studies suggest that the rhodium complex simultaneously serves as the catalytic center and photosensitizer for decarbonylation.
Our previous study demonstrated that heterogeneous nuclear ribonucleoprotein AB (HNRNPAB) is a key gene that facilitates metastasis of hepatocellular carcinoma (HCC). However, the molecular ...mechanisms behind this relationship are not fully understood. In our study, we utilized long‐noncoding RNA (lncRNA) microarrays to identify a HNRNPAB‐regulated lncRNA named lnc‐ELF209. Our findings from chromatin immunoprecipitation assays indicate that HNRNPAB represses lnc‐ELF209 transcription by directly binding to its promoter region. We also analyzed clinical samples from HCC patients and cell lines with quantitative real‐time polymerase chain reactions, RNA in situ hybridization and immunohistochemistry, and found that there is a negative relationship between HNRNPAB and lnc‐ELF209 expression. Up/downregulation assays and rescue assays indicate that lnc‐ELF209 inhibits cell migration, invasion and epithelial–mesenchymal transition regulated by HNRNPAB. This suggests a new regulatory mechanism for HNRNPAB‐promoted HCC progression. RNA pull‐down and LC–MS/MS were used to determine triosephosphate isomerase, heat shock protein 90‐beta and vimentin may be involved in the tumor‐suppressed function of lnc‐ELF209. Furthermore, we found lnc‐ELF209 could stabilize TPI protein expression. We also found that lnc‐ELF209 overexpression in HCCLM3 cell resulted in a lower rate of lung metastatic, which suggested a less aggressive HCC phenotype. Collectively, these findings offer new insights into the regulatory mechanisms that underlie HNRNPAB cancer‐promoting activities and demonstrate that lnc‐ELF209 is a HNRNPAB‐regulated lncRNA that may play an important role in the inhibition of HCC progression.
What's new?
Increased levels of the protein HNRNPAB can facilitate metastasis of hepatocellular carcinoma (HCC). But how does it do this? In this study, the authors found that HNRNPAB can repress a previously uncharacterized long noncoding RNA (lncRNA), called lnc‐ELF209. They then found that lnc‐ELF209 plays a crucial role in inhibiting the migration, invasion, and epithelial‐mesenchymal transition (EMT) of HCC tumor cells. Further analysis of this HNRNPAB‐lncELF209 regulatory axis should enhance our understanding of the molecular mechanisms involved in HCC, which may in turn lead to new therapeutic candidates.
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