The metastable pitting corrosion behavior of laser powder bed fusion (LPBF) produced Ti-6Al-4V is still unclear. Therefore, this work investigated the metastable pitting corrosion of LPBF-produced ...Ti-6Al-4V in Hank’s solution by electrochemical methods. The LPBF-produced sample (dominant by α′ phase in the microstructure) shows a higher frequency of pit nucleation than the annealed counterpart (composed by α + β dual phase). The passive films formed on the LPBF-produced sample exhibit a higher flux of oxygen vacancies, resulting in the absorption of more aggressive ions (e.g., Cl-) thereby producing more cation vacancies. The condensation of excessive cation vacancies contributes to the pit nucleation.
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•Laser powder bed fusion (LPBF) produced Ti–6Al–4 V alloy was used as the sample.•Corrosion behavior of the LPBF-produced sample was investigated in Hank’s solution.•The LPBF-produced Ti-6Al-4 V shows frequent metastable pitting corrosion.•The flux of oxygen vacancy is large in the passive film of LPBF-produced Ti-6Al-4 V.•Redundant vacancies assemble and condense into a void at metal/film interface.
Newborn microglia rapidly replenish the whole brain after selective elimination of most microglia (>99%) in adult mice. Previous studies reported that repopulated microglia were largely derived from ...microglial progenitor cells expressing nestin in the brain. However, the origin of these repopulated microglia has been hotly debated. In this study, we investigated the origin of repopulated microglia by a series of fate-mapping approaches. We first excluded the blood origin of repopulated microglia via parabiosis. With different transgenic mouse lines, we then demonstrated that all repopulated microglia were derived from the proliferation of the few surviving microglia (<1%). Despite a transient pattern of nestin expression in newly forming microglia, none of repopulated microglia were derived from nestin-positive non-microglial cells. In summary, we conclude that repopulated microglia are solely derived from residual microglia rather than de novo progenitors, suggesting the absence of microglial progenitor cells in the adult brain.
As we conclude this Special Edition of “Energy Converter: Anaerobic Digestion”, a lingering sense of both achievement and anticipation accompanies us ...
Expedient hydroarylations of C=Het bonds (Het=heteroatom) were accomplished by user‐friendly organometallic C−H activation in a positional‐selective manner. The broadly applicable C−H ...functionalization platform enabled the step‐economical transformation of aldehydes, ketones, and imines under additive‐free reaction conditions. In contrast to palladium, rhodium, ruthenium, rhenium, iridium, nickel, and cobalt catalysis, solely manganese(I) complexes outcompeted the innate substrate control, clearly highlighting the unique power of manganese(I) C−H activation catalysis.
One catalyst to rule them all: The unique selectivity of manganese(I) catalysis in heteroarene C−H activation set the stage for positional selective hydroarylations with ample scope under additive‐free conditions, outcompeting palladium, rhodium, ruthenium, rhenium, iridium, nickel, iron, and cobalt catalysts.
An efficient Mn-catalyzed aerobic oxidative hydroxyazidation of olefins for synthesis of β-azido alcohols has been developed. The aerobic oxidative generation of azido radical employing air as the ...terminal oxidant is disclosed as the key process for this transformation. The reaction is appreciated by its broad substrate scope, inexpensive Mn-catalyst, high efficiency, easy operation under air, and mild conditions at room temperature. This chemistry provides a novel approach to high value-added β-azido alcohols, which are useful precursors of aziridines, β-amino alcohols, and other important N- and O-containing heterocyclic compounds. This chemistry also provides an unexpected approach to azido substituted cyclic peroxy alcohol esters. A DFT calculation indicates that Mn catalyst plays key dual roles as an efficient catalyst for the generation of azido radical and a stabilizer for peroxyl radical intermediate. Further calculation reasonably explains the proposed mechanism for the control of C-C bond cleavage or for the formation of β-azido alcohols.
Electrochemical reduction of N
to NH
provides an alternative to the Haber-Bosch process for sustainable, distributed production of NH
when powered by renewable electricity. However, the development ...of such process has been impeded by the lack of efficient electrocatalysts for N
reduction. Here we report efficient electroreduction of N
to NH
on palladium nanoparticles in phosphate buffer solution under ambient conditions, which exhibits high activity and selectivity with an NH
yield rate of ~4.5 μg mg
h
and a Faradaic efficiency of 8.2% at 0.1 V vs. the reversible hydrogen electrode (corresponding to a low overpotential of 56 mV), outperforming other catalysts including gold and platinum. Density functional theory calculations suggest that the unique activity of palladium originates from its balanced hydrogen evolution activity and the Grotthuss-like hydride transfer mechanism on α-palladium hydride that lowers the free energy barrier of N
hydrogenation to *N
H, the rate-limiting step for NH
electrosynthesis.
Shuxuening injection (SXNI), a popular herbal medicine, is an extract of Ginkgo biloba leaves (GBE), and is used to treat ischemic stroke (IS) in China. However, its specific active ingredients and ...molecular mechanisms in IS remain unclear.
Aim of the study: The purpose of the research is to identify the main active ingredients in GBE and explore its molecular mechanisms in the treatment of IS.
The main active components of GBE were discerned through the Traditional Chinese Medicine Systems Pharmacology Database and Analysis (TCMSP), Traditional Chinese Medicine Integrated Database (TCMID), Bioinformatics Analysis Tool for Molecular Mechanism of Traditional Chinese Medicine (BATMAN-TCM) database, and absorption, distribution, metabolism and excretion (ADME) analysis. The targets related to IS were obtained using Genecards, Online Mendelian Inheritance in Man (OMIM), Therapeutic Target Database (TTD), and Disgenet. We discovered an intersection of genes. Subsequently, protein-protein interaction (PPI) networks were constructed with Cytoscape 3.7.1 and the String database. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to analyze the intersection of targets via the Database for Annotation, Visualization, and Integrated Discovery (DAVID) 6.8. Built on the above analysis, we made a Compound-Target-Pathway (C-T-P) network. Autodock Vina was used for molecular docking analysis. Maestro 11.9 was used to calculate the root-mean-square deviation (RMSD). Animal experiments were performed to verify the core targets. Triphenyl tetrazolium chloride (TTC) staining was used to calculate the infarct volume in rats. Hematoxylin-eosin (HE) staining was employed to observe the morphology of hippocampal neuron cells. RT-qPCR was applied to detect relative mRNA levels, and protein expression was determined using Western blotting.
Molecular docking showed that PTGS2, NOS3 and CASP3 docked with small molecule compounds. According to RT-qPCR and Western blotting, mRNA and protein expression of PTGS2 and CASP3 were up-regulated (P < 0.05), and mRNA and protein levels of NOS3 were down-regulated (P < 0.05).
SXNI can treat IS through multiple targets and routes, and reduce the apoptosis of neuron cells in brain tissue by inhibiting inflammation and regulating the level of oxidative stress, thereby protecting rats brain tissue.
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Electronic health records (EHRs) can provide researchers with extraordinary opportunities for population-based research. The National Health Insurance system of Taiwan was established in 1995 and ...covers more than 99.6% of the Taiwanese population; this system's claims data are released as the National Health Insurance Research Database (NHIRD). All data from primary outpatient departments and inpatient hospital care settings after 2000 are included in this database. After a change and update in 2016, the NHIRD is maintained and regulated by the Data Science Centre of the Ministry of Health and Welfare of Taiwan. Datasets for approved research are released in three forms: sampling datasets comprising 2 million subjects, disease-specific databases, and full population datasets. These datasets are de-identified and contain basic demographic information, disease diagnoses, prescriptions, operations, and investigations. Data can be linked to government surveys or other research datasets. While only a small number of validation studies with small sample sizes have been undertaken, they have generally reported positive predictive values of over 70% for various diagnoses. Currently, patients cannot opt out of inclusion in the database, although this requirement is under review. In conclusion, the NHIRD is a large, powerful data source for biomedical research.
Spermatogonial stem cells (SSCs) are a subpopulation of undifferentiated spermatogonia located in a niche at the base of the seminiferous epithelium delimited by Sertoli cells and peritubular myoid ...(PM) cells. SSCs self-renew or differentiate into spermatogonia that proliferate to give rise to spermatocytes and maintain spermatogenesis. Glial cell line-derived neurotrophic factor (GDNF) is essential for this process. Sertoli cells produce GDNF and other growth factors and are commonly thought to be responsible for regulating SSC development, but limited attention has been paid to the role of PM cells in this process. A conditional knockout (cKO) of the androgen receptor gene in PM cells resulted in male infertility. We found that testosterone (T) induces GDNF expression in mouse PM cells in vitro and neonatal spermatogonia (including SSCs) co-cultured with T-treated PM cells were able to colonize testes of germ cell-depleted mice after transplantation. This strongly suggested that T-regulated production of GDNF by PM cells is required for spermatogonial development, but PM cells might produce other factors in vitro that are responsible. In this study, we tested the hypothesis that production of GDNF by PM cells is essential for spermatogonial development by generating mice with a cKO of the Gdnf gene in PM cells. The cKO males sired up to two litters but became infertile due to collapse of spermatogenesis and loss of undifferentiated spermatogonia. These studies show for the first time, to our knowledge, that the production of GDNF by PM cells is essential for undifferentiated spermatogonial cell development in vivo
The Amazon river basin receives ~2000 mm of precipitation annually and contributes ~17% of global river freshwater input to the oceans; its hydroclimatic variations can exert profound impacts on the ...marine ecosystem in the Amazon plume region (APR) and have potential far-reaching influences on hydroclimate over the tropical Atlantic. Here, we show that an amplified seasonal cycle of Amazonia precipitation, represented by the annual difference between maximum and minimum values, during the period 1979-2018, leads to enhanced seasonalities in both Amazon river discharge and APR ocean salinity. An atmospheric moisture budget analysis shows that these enhanced seasonal cycles are associated with similar amplifications in the atmospheric vertical and horizontal moisture advections. Hierarchical sensitivity experiments using global climate models quantify the relationships of these enhanced seasonalities. The results suggest that an intensified hydroclimatological cycle may develop in the Amazonia atmosphere-land-ocean coupled system, favouring more extreme terrestrial and marine conditions.
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