The pathways by which mild hypothermia inhibits neuronal apoptosis following ischemia/reperfusion injury

Several studies have demonstrated that mild hypothermia exhibits a neuroprotective role and it can inhibit endothelial cell apoptosis following ischemia/reperfusion injury by decreasing casp- ase-3 expression, It is hypothesized that mild hypothermia exhibits neuroprotective effects on neurons exposed to ischemia/reperfusion condition produced by oxygen-glucose deprivation. Mild hypothermia significantly reduced the number of apoptotic neurons, decreased the expres- sion of pro-apoptotic protein Bax and increased mitochondrial membrane potential, with the peak of anti-apoptotic effect appearing between 6 and 12 hours after the injury. These findings indicate that mild hypothermia inhibits neuronal apoptosis following ischemia/reperfusion injury by protecting the mitochondria and that the effective time window is 6-12 hours after ischemia/reperfusion injury.

我国化学奥林匹克竞赛研究综述

通过对我国化学奥林匹克竞赛(以下可简称“化学奥赛”或“竞赛”)相关文献的回顾和梳理,发现我国学者对国内化学奥赛的研究主要集中在五个方面,包括竞赛试题解析、竞赛培训策略、地区现状研究、竞赛评述研究以及国内外化学奥赛对比分析。结果发现:试题研究和竞赛培训是两大研究热点,关于某一地区化学奥赛发展现状的研究则较少,仅仅只对几个地区开展了研究。在竞赛培训研究中,学者除了聚焦学生思维、解题技巧方面的培养,逐渐开始关注学生的兴趣、自主学习以及合作学习,而且随着化学学科核心素养的提出,也陆续有一些学者开展这一化学教育热点与化学奥赛的相关研究(主要集中在试题研究和竞赛培训两大领域)。

Misfit strains inducing voltage decay in LiMn_(y)Fe_(1-y)PO_(4)/C

LiMn_(y)Fe_(1-y)PO_(4) is considered a promising cathode material for next-generation lithium-ion batteries(LIBs) due to its high energy density and low cost. Its energy density degradation is often ascribed to the capacity loss during cycling. However, in this study, we find that the energy density degradation mainly roots in voltage decay. We have synthesized a series of LiMn_(y)Fe_(1-y)PO_(4) /C(0.5 ≤ y ≤ 0.8) and find this voltage decay is correlated with the Mn content. A high amount Mn leads to a heavier voltage decay.In-situ X-ray diffraction(XRD) and high-resolution transmission electron microscopy(HRTEM) reveal the nature of this effect, which show a mismatch along the b-axis of-2.68%(charge) and +3.4%(discharge), a volume misfit of-4.41%(charge) and +4.54%(discharge) between Li_(x)Mn_(y)Fe_(1-y)PO_(4) and Mn_(y)Fe_(1-y)PO_(4) during phase transitions. The resultant misfit strains during Li+insertion compared to extraction result in structural degradations, such as amorphization and impurity(Mn F3) accumulation after cycling. The voltage decay can be alleviated by kinetic relaxations and recovered by a wild reannealing. This work demonstrates effective strategies to improve the energy density and cycling performance of LiMn_(y)Fe_(1-y)PO_(4) /C,providing good references for other LIB cathodes, such as the Li-rich cathodes.

Aurivillius compound Bi_(5)Ti_(3)CrO_(15) as a visible-light-active photocatalyst for hydrogen production from water

Layered Aurivillius compound Bi_(5)Ti_(3)CrO_(15) has been synthesized by a hydrothermal method for the application as a photocatalyst to liberate hydrogen from water. Bi_(5)Ti_(3)CrO_(15) owns a narrow band gap (Eg ~2.46 eV) and shows stable photocatalytic activity under both full range (λ ≥250 nm) and visible light illumination (λ ≥420 nm). A short hydrothermal reaction time is critical to achieve high photocatalytic activity as defects such as Cr^(6+) and Bi^(5+) can be avoided. An AQE as high as 3.66% at 420 nm ± 20 nm has been recorded, warranting promising application in the field of solar energy conversions. DFT calculation reveals the important role of Cr^(3+) cations for visible light sensitivity of Bi_(5)Ti_(3)CrO_(15).

Manipulating vector solitons with super-sech pulse shapes

Theoretical simulations about manipulating vector solitons with super-sech pulse shapes are conducted based on an optical fiber system.By changing the temporal pulses’parameters when the orthogonally polarized pulses have the same or different input central wavelengths,the output modes in orthogonal directions will demonstrate different properties.When the input orthogonal modes have the same central wavelength,the“2+2”pseudo-high-order vector soliton can be generated when the time delay is changed.While under the condition of different central wavelengths,orthogonal pulses with multiple peaks accompanied with two wavelengths can be achieved through varying the projection angle,time delay or phase difference.Our simulations are helpful to the study of optical soliton dynamics in optical fiber systems.

Characterization of cyclophilin D in freshwater pearl mussel (Hyriopsis schlegelii)

Cyclophilin D （referred to as HsCypD） was obtained from the freshwater pearl mussel （Hyriopsis schlegelil）. The full-length cDNA was 2 671 bp, encoding a protein consisting of 367 amino acids. HsCypD was determined to be a hydrophilic intracellular protein with 10 phosphorylation sites and four tetratricopeptide repeat （TPR） domains, but no signal peptide. The core sequence region YKGCIFHRIIKDFMVQGG is highly conserved in vertebrates and invertebrates. Phylogenetic tree analysis indicated that CypD from all species had a common origin, and HsCypD had the closest phylogenetic relationship with CypD from Lottia gigantea. The constitutive mRNA expression levels of HsCypD exhibited tissue-specific patterns, with the highest level detected in the intestines, followed by the gonads, and the lowest expression found in the hemocytes.

FeSO_(4) as a Novel Li-Ion Battery Cathode

FeSO_(4) has the characteristics of low cost and theoretical high energy density(799 W·h·kg^(-1) with a two-electron reaction),which can meet the demand for next-generation lithium-ion batteries.Herein,FeSO_(4) as a novel highperformance conversion-reaction type cathode is investigated.We use dopamine as a carbon coating source to increase its electronic conductivity.FeSO_(4)@C demonstrates a high reversible specific capacity(512 mA·h·g^(-1))and a superior cycling performance(482 mA·h·g^(-1) after 250 cycles).In addition,we further study its reaction mechanism.The FeSO_(4) is converted to Fe and Li2SO_(4) during lithium ion insertion and the Fe-Li_(2)SO_(4) grain boundaries further store additional lithium ions.Our findings are valuable in exploring other new conversion-type lithium ion battery cathodes.

Catalytic Arylalkylation of Alkenyl Amines at Remote Sites via Directed Nickel Catalysis

Directing group-assisted, transition metal-catalyzed three-component difunctionalization of alkenes has emerged as a powerful tool to drive molecular complexity. However, this strategy generally works with the substrates bearing directing groups in close proximity to the alkene moieties, due to the preference for formation of kinetically stable five-membered metallacycles. Herein, we have disclosed a complementary strategy to accomplish a nickel-catalyzed remote arylalkylation of alkenyl amines with excellent regioselectivity and diastereofidelity, involving rare six- or seven-membered metallacycles. This general protocol is compatible with a series of δ- and ε-alkenyl amines, providing corresponding valuable δ,ε- and ε,ζ-difunctionalized aliphatic amines that would be difficult to synthesize. The coordination of the bidentate picolinamide auxiliary and the facile oxidative addition of alkyl halides to Ni(I) species are the key to the success of the developed remote olefin dicarbofunctionalization.

Haemorrhage risk of brain arteriovenous malformation during pregnancy and puerperium

Background This study aimed to assess whether pregnancy and puerperium were associated with the risk of brain arteriovenous malformation(bAVM)haemorrhage.Methods A retrospective review was conducted in Xiangya Hospital,Central South University from January 2012 to December 2021.A case-crossover design was adopted to calculate the incidence density of bAVM-related haemorrhage among female patients in risk(pregnancy and puerperium)and control(non-pregnancy and non-puerperium)periods,according to four scenarios observed in different populations scenario I:patients with haemorrhagic bAVM of all ages;scenario II:patients with haemorrhagic bAVM of all ages,with at least one previous pregnancy;scenario III:patients with haemorrhagic bAVM who are of reproductive age(15-45 years);scenario IV:patients with haemorrhagic bAVM of reproductive age(15-45 years),with at least one previous pregnancy.Next,a comprehensive literature aggregation(up to April 2022)was performed for evidence synthesis.Results Among the 311 female patients with haemorrhagic bAVM,a significant haemorrhage risk during pregnancy and puerperium was found in Scenarios I(relative risk[RR],2.08;95%CI,1.28 to 3.39),II(RR,3.21;95%CI,1.95 to 5.31)and IV(RR,2.92;95%CI,1.73 to 4.93);however,a suggestive risk was found in scenario III(RR,1.62;95%CI,0.99 to 2.67).Evidence synthesis revealed a consistent haemorrhage risk among patients of all ages(RR,3.15;95%CI,1.93 to 5.15)and those of reproductive age(RR,1.29;95%CI,0.89 to 1.86).Conclusion Compared with most previous studies,a higher but relatively moderate risk for bAVM-related haemorrhage was identified during pregnancy and puerperium.Individualised prevention and treatment strategies should be preferred when neurosurgeons make clinical decisions.

Magnetic covalent organic framework nanospheres-based miRNA biosensor for sensitive glioma detection

Sensitive detection and accurate diagnosis/prognosis of glioma remain urgent challenges.Herein,dispersed magnetic covalent organic framework nanospheres(MCOF)with uniformed Fe3O4 nano-assembly as cores and high-crystalline COF as shells were prepared by monomer-mediated in-situ interface growth strategy.Based on the unique interaction between MCOF and hairpin DNA,a fluorescent signal amplified miRNA biosensor was constructed.It could realize the sensitive detection of miRNA-182 in different matrixes,where the detection limit,linearity range and determination coefficient(R^(2))in real blood samples reached 20 fM,0.1 pM-10 pM and 0.991,respectively.Also,it possessed good stability and precision as observed from the low intra-day/inter-day RSD and high extraction recovery.As a result,it could quantify miRNA-182 in serum of glioma patients,the concentration of which was significantly higher than that of healthy people and obviously decreased after surgery.Finally,a proof-of-concept capillary chip system using this biosensor was proposed to realize the visualized detection of miRNA-182 in microsample.These findings suggest a robust way for sensitive detection and accurate diagnosis/prognosis of glioma.

MEK2 is a prognostic marker and potential chemo-sensitizing target for glioma patients undergoing temozolomide treatment

Although temozolomide （TMZ） is the first-line chemotherapeutic agent for glioblastoma, it is often non-curative due to drug resistance. To overcome the resistance of glioblastoma cells to TMZ, it is imperative to identity prognostic markers for outcome prediction and to develop chemo-sensitizing agents. Here, the gene expression profiles of TMZ-resistant and TMZ-sensitive samples were compared by microarray analysis, and mitogen-activated protein kinase kinase 2 （MEK2） was upregulated specifically in resistant glioma cells but not in sensitive tumor cells or non-tumor tissues. Moreover, a comprehensive analysis of patient data revealed that the increased level of MEK2 expression correlated well with the advancement of glioma grade and worse prognosis in response to TMZ treatment. Furthermore, reducing the level of MEK2 in U251 glioma cell lines or xenografted glioma models through shRNA-mediated gene knockdown inhibited cell proliferation and enhanced the sensitivity of cells toward TMZ treatment. Further analysis of tumor samples from glioma patients by real-time PCR indicated that an increased MEK2 expression level was closely associated with the activation of many drug resistance genes. Finally, these resistance genes were downregulated after MEK2 was silenced in vitro, suggesting that the mechanism of MEK2-induced chemo-resistance could be mediated by the transcriptional activation of these resistance genes. Collectively, our data indicated that the expression level of MEK2 could serve as a prognostic marker for glioma chemotherapy and that MEK2 antagonists can be used as chemo-sensitizers to enhance the treatment efficacy of TMZ.