The development of electrocatalysts to generate hydrogen, with good activity and stability, is a great challenge in the fields of chemistry and energy. Here we demonstrate a “hitting three birds ...with one stone” method to synthesize less toxic metallic WO2–carbon mesoporous nanowires with high concentration of oxygen vacancies (OVs) via calcination of inorganic/organic WO3–ethylenediamine hybrid precursors. The products exhibit excellent performance for H2 generation: the onset overpotential is only 35 mV, the required overpotentials for 10 and 20 mA/cm2 are 58 and 78 mV, the Tafel slope is 46 mV/decade, the exchange current density is 0.64 mA/cm2, and the stability is over 10 h. Further studies, in combination with density functional theory, demonstrate that the unusual electronic structure and the large amount of active sites, generated by the high concentration of OVs, as well as the closely attached carbon materials, were key factors for excellent performance. Our results experimentally and theoretically establish metallic transition metal oxides (TMOs) as intriguing novel electrocatalysts for H2 generation. Such TMOs with OVs might be promising candidates for other energy storage and conversion applications.
The unique optoelectronic properties and promising photovoltaic applications of organolead halide perovskites have driven the exploration of facile strategies to synthesize organometal halide ...perovskites and corresponding hybrid materials and devices. Currently, the preparation of CH3NH3PbBr3 perovskite nanowires, especially those with porous features, is still a great challenge. An efficient self‐template‐directed synthesis of high‐quality porous CH3NH3PbBr3 perovskite nanowires in solution at room temperature using the Pb‐containing precursor nanowires as both the sacrificial template and the Pb2+ source in the presence of CH3NH3Br and HBr is now presented. The initial formation of CH3NH3PbBr3 perovskite layers on the surface of the precursor nanowires and the following dissolution of the organic component of the latter led to the formation of mesopores and the preservation of the 1D morphology. Furthermore, the perovskite nanowires are potential materials for visible‐light photodetectors with high sensitivity and stability.
In solution: Porous CH3NH3PbBr3 perovskite nanowires (PNW‐CH3NH3PbBr3) were fabricated by an efficient self‐template‐directed synthesis using the Pb‐containing precursor nanowires as both the sacrificial template and the Pb2+ source in the presence of CH3NH3Br and HBr in solution. The perovskite nanowires are potential materials for visible‐light photodetectors.
The continuous consumption of fossil fuels and accompanying environmental problems are driving the exploration of low-cost and effective electrocatalysts to produce clean hydrogen. A Ni2P ...nanosheets/Ni foam composite, as a non-noble metal electrocatalyst, has been prepared through a facile chemical conversion pathway using surface oxidized Ni foam as precursor and low concentration of trioctylphosphine (TOP) as a phosphorus source. Further investigation shows the oxidized layer of Ni foam can orient the formation of Ni2P nanosheets and facilitate the reaction with TOP. The Ni2P/Ni, acting as a robust 3D self-supported superaerophobic hydrogen-evolving cathode, shows superior catalytic performance, stability, and durability in aqueous media over a wide pH value of 0–14, making it a versatile catalyst system for hydrogen generation. Such highly active, stable, abundant, and low-cost materials hold enormously promising potential applications in the fields of catalysis, energy conversion, and storage.
Nine flavonoids were isolated and characterized from the leaves of Zanthoxylum bungeanum. Their structures were elucidated by spectroscopic techniques as quercetin (1), afzelin (2), quercitrin (3), ...trifolin (4), quercetin-3-O-β-D-glucoside (5), isorhamnetin 3-O-α-L-rhamnoside (6), hyperoside (7), vitexin (8) and rutin (9). All compounds were isolated from the leaves of Z. bungeanum for the first time. Five compounds (2, 4, 5, 6 and 8) were found for the first time in the genus Zanthoxylum. To learn the mechanisms underlying its health benefits, in vitro (DPPH, ABTS, FRAP and lipid peroxidation inhibition assays) and in vivo (protective effect on Escherichia coli under peroxide stress) antioxidant activities of the nine flavonoids were measured. Quercetin and quercetin glycosides (compounds 1, 3, 5, 7, 9) showed the highest antioxidant activity. Structure-activity relationships indicated that the -OH in 4' position on the B ring and the -OH in 7 position on the A ring possessed high antioxidant activity; B ring and/or A ring with adjacent -OH groups could greatly increase their antioxidant ability. Also, due to the different structures of various flavonoids, they will certainly exhibit different antioxidant capacity when the reactions occur in solution or in oil-in-water emulsion. These findings suggest that Z. bungeanum leaves may have health benefits when consumed. It could become a useful supplement for pharmaceutical products and functional food ingredients in both nutraceutical and food industries as a potential source of natural antioxidants.
Existing studies on climate change effects on crop yields mainly focus on the average climate–yield relationship that is typically assumed to be time-invariant. We apply a flexible panel-data ...quantile regression with time-varying coefficients to examine distributional heterogeneity and temporal variation in this relationship. We find that U.S. corn and soybean yields have gradually become less sensitive to temperature and precipitation over 1948–2010, which is especially the case for upper yield quantiles. Consequently, the negative impacts of future climate change are of larger magnitudes at the lower yield quantiles. Failure to accommodate temporal changes in the climate–yield relationship leads to significantly overestimated responsiveness of crop yields to weather variation and, therefore, overestimated negative impacts of future climate change. On many occasions, the corn yield decline projections from such time-invariant specifications are about twice as large as (and sometimes triple) the predictions from our time-varying-coefficient model.
Current pathology workflow involves staining of thin tissue slices, which otherwise would be transparent, followed by manual investigation under the microscope by a trained pathologist. While the ...hematoxylin and eosin (H&E) stain is well-established and a cost-effective method for visualizing histology slides, its color variability across preparations and subjectivity across clinicians remain unaddressed challenges. To mitigate these challenges, recently, we have demonstrated that spatial light interference microscopy (SLIM) can provide a path to intrinsic objective markers that are independent of preparation and human bias. Additionally, the sensitivity of SLIM to collagen fibers yields information relevant to patient outcome, which is not available in H&E. Here, we show that deep learning and SLIM can form a powerful combination for screening applications: training on 1660 SLIM images of colon glands and validating on 144 glands, we obtained an accuracy of 98% (validation dataset) and 99% (test dataset), resulting in benign vs cancer classification accuracy of 97%, defined as area under the receiver operating characteristic curve. We envision that the SLIM whole slide scanner presented here paired with artificial intelligence algorithms may prove valuable as a pre-screening method, economizing the clinician’s time and effort.
Drug Inducible CRISPR/Cas Systems Zhang, Jingfang; Chen, Li; Zhang, Ju ...
Computational and structural biotechnology journal,
01/2019, Volume:
17
Journal Article
Peer reviewed
Open access
Clustered, regularly interspaced, short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) systems have been employed as a powerful versatile technology for programmable gene editing, ...transcriptional modulation, epigenetic modulation, and genome labeling, etc. Yet better control of their activity is important to accomplish greater precision and to reduce undesired outcomes such as off-target events. The use of small molecules to control CRISPR/Cas activity represents a promising direction. Here, we provide an updated review on multiple drug inducible CRISPR/Cas systems and discuss their distinct properties. We arbitrarily divided the emerging drug inducible CRISPR/Cas systems into two categories based on whether at transcription or protein level does chemical control occurs. The first category includes Tet-On/Off system and Cre-dependent system. The second category includes chemically induced proximity systems, intein splicing system, 4-Hydroxytamoxifen-Estrogen Receptor based nuclear localization systems, allosterically regulated Cas9 system, and destabilizing domain mediated protein degradation systems. Finally, the advantages and limitations of each system were summarized.
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An organocatalytic Cloke–Wilson rearrangement of cyclopropyl ketones to 2,3-dihydrofurans is exploited utilizing the homoconjugate addition process. With 1,4-diazabicyclo2.2.2octane as the catalyst, ...the rearrangement in DMSO at 120 °C proceeded in generally high yields, exclusive regioselectivity, and a broad substrate scope. An examination of the mechanism including stereochemical analysis and intermediate isolation supports an SN1-type ring opening of the mechanism.
The SLC12A cation-Cl
cotransporters (CCC), including NKCC1 and the KCCs, are important determinants of brain ionic homeostasis. SPAK kinase (STK39) is the CCC master regulator, which stimulates NKCC1 ...ionic influx and inhibits KCC-mediated efflux via phosphorylation at conserved, shared motifs. Upregulation of SPAK-dependent CCC phosphorylation has been implicated in several neurological diseases. Using a scaffold-hybrid strategy, we develop a novel potent and selective SPAK inhibitor, 5-chloro-N-(5-chloro-4-((4-chlorophenyl)(cyano)methyl)-2-methylphenyl)-2-hydroxybenzamide ("ZT-1a"). ZT-1a inhibits NKCC1 and stimulates KCCs by decreasing their SPAK-dependent phosphorylation. Intracerebroventricular delivery of ZT-1a decreases inflammation-induced CCC phosphorylation in the choroid plexus and reduces cerebrospinal fluid (CSF) hypersecretion in a model of post-hemorrhagic hydrocephalus. Systemically administered ZT-1a reduces ischemia-induced CCC phosphorylation, attenuates cerebral edema, protects against brain damage, and improves outcomes in a model of stroke. These results suggest ZT-1a or related compounds may be effective CCC modulators with therapeutic potential for brain disorders associated with impaired ionic homeostasis.
Exposure to ambient air-borne fine particulate matter (PM2.5) increases respiratory morbidity and mortality. The mechanisms underlying PM2.5-induced adverse effects remain unclear. This study aimed ...to uncover the molecular mechanisms of PM2.5-induced lung toxicity using a mouse model.
Scanning electron microscopy and inductively coupled plasma mass spectrometry were used to examine and analyze PM2.5 morphology and element compositions, respectively. Twenty four male mice were randomly divided into three groups: control (PBS), PM2.5 (4.0 mg/kg b.w.), and PM2.5 + Z-YVAD-FMK. In the latter group, the pan-caspase inhibitor (Z-YVAD-FMK) was intraperitoneally injected into mice at a dose of 12.5 mg/kg body weight prior to intratracheal instillation of PM2.5 (4.0 mg/kg b.w.) every other day for a total of 3 times (n = 8 in each group). Bronchoalveolar lavage fluids (BALFs) were collected 24 h after the last instillation of PM2.5. Levels of total proteins (TP), lactate dehydrogenase (LDH), IL-1β and IL-18 were analyzed for biomarkers of cell injury and inflammation. Additionally, histological alterations of lung tissues were assessed by hematoxylin-eosin staining. mRNA and protein expression of Caspase1, NLRP3 and GSDMD were examined by real-time fluorescent quantitative PCR and immunohistochemical staining.
Exposure to PM2.5 increased levels of TP, LDH, IL-1β, IL-18 and inflammatory cell counts in lung. The mRNA and protein expression of Caspase1, NLRP3 and GSDMD were increased. Inhibition of the NALRP3/Caspase-1 signaling pathway ameliorated PM2.5-induced lung injury and inflammation, partially through suppressing pyroptosis in lung.
PM2.5 exposure induces lung injury and inflammation, which is mediated by the NALRP3/Caspase-1 signaling pathway.
•PM2.5 exposure caused lung injury and inflammation in mice.•Inhibition of NALRP3/Caspase-1 signaling pathway can amelioration PM2.5-induced lung toxicity.•PM2.5 exposure induced lung toxicity is related to NALRP3 inflammasome mediated macrophage pyroptosis.
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