Oxidation Evolution and Activity Origin of N-Doped Carbon in the Oxygen Reduction Reaction

N-doped carbon materials,with their applications as electrocatalysts for the oxygen reduction reaction(ORR),have been extensively studied.However,a negletcted fact is that the operating potential of the ORR is higher than the theoretical oxida-tion potential of carbon,possibly leading to the oxidation of carbon materials.Consequently,the infl uence of the structural oxidation evolution on ORR performance and the real active sites are not clear.In this study,we discover a two-step oxida-tion process of N-doped carbon during the ORR.The fi rst oxidation process is caused by the applied potential and bubbling oxygen during the ORR,leading to the oxidative dissolution of N and the formation of abundant oxygen-containing functional groups.This oxidation process also converts the reaction path from the four-electron(4e)ORR to the two-electron(2e)ORR.Subsequently,the enhanced 2e ORR generates oxidative H_(2)O_(2),which initiates the second stage of oxidation to some newly formed oxygen-containing functional groups,such as quinones to dicarboxyls,further diversifying the oxygen-containing functional groups and making carboxyl groups as the dominant species.We also reveal the synergistic eff ect of multiple oxygen-containing functional groups by providing additional opportunities to access active sites with optimized adsorption of OOH*,thus leading to high effi ciency and durability in electrocatalytic H_(2)O_(2) production.

北京市学分银行建设问题研究

为了适应我国建设一个面向全民的终身教育体系,加速职业教育国家学分银行建设,北京市经过两年多的实践探索,产生了一些实践案例。本研究对当前北京市政府推进学分银行建设进行梳理和研究,阐述了北京市学分银行建设的现状,通过研究认为当前在学分银行建设中,存在法律法规不健全,制度保障不到位,平台建设资金投入不足,认证与转换标准体系建设推进缓慢,公民参与率、知晓率低,学分银行公信力低等六个方面主要问题,提出了加快法律法规体系建设,完善学分银行制度保障体系建设,加大平台投入,建设智能化学分银行应用平台,强化学分银行运行标准化体系建设,加强学分银行知晓度和参与度建设,多维度促进学分银行公信力建设的对策建议。

Heat shock protein 90 promotes RNA helicase DDX5 accumulation and exacerbates hepatocellular carcinoma by inhibiting autophagy

Objective:Hepatocellular carcinoma(HCC),the main type of liver cancer,has a high morbidity and mortality,and a poor prognosis.RNA helicase DDX5,which acts as a transcriptional co-regulator,is overexpressed in most malignant tumors and promotes cancer cell growth.Heat shock protein 90(HSP90)is an important molecular chaperone in the conformational maturation and stabilization of numerous proteins involved in cell growth or survival.Methods:DDX5 m RNA and protein expression in surgically resected HCC tissues from 24 Asian patients were detected by quantitative real-time PCR and Western blot,respectively.The interaction of DDX5-HSP90 was determined by molecular docking,immunoprecipitation,and laser scanning confocal microscopy.The autophagy signal was detected by Western blot.The cell functions and signaling pathways of DDX5 were determined in 2 HCC cell lines.Two different murine HCC xenograft models were used to determine the function of DDX5 and the therapeutic effect of an HSP90 inhibitor.Results:HSP90 interacted directly with DDX5 and inhibited DDX5 protein degradation in the AMPK/ULK1-regulated autophagy pathway.The subsequent accumulation of DDX5 protein induced the malignant phenotype of HCC by activating theβ-catenin signaling pathway.The silencing of DDX5 or treatment with HSP90 inhibitor both blocked in vivo tumor growth in a murine HCC xenograft model.High levels of HSP90 and DDX5 protein were associated with poor prognoses.Conclusions:HSP90 interacted with DDX5 protein and subsequently protected DDX5 protein from AMPK/ULK1-regulated autophagic degradation.DDX5 and HSP90 are therefore potential therapeutic targets for HCC.

Abnormal accumulation of RNA helicase DDX5 protein promotes malignancy of hepatocellular carcinoma

Objective:Hepatocellular carcinoma(HCC),the most common type of liver cancer,has a high morbidity and mortality rate,and poor prognosis.There is currently no effective treatment for HCC.RNA helicase DDX5,which acts as a transcriptional co-regulator,is overexpressed in most malignant tumors and promotes cancer cell activities.

NLRP6 is correlated with the progression and therapeutic outcome of hepatocellular carcinoma and inhibits the function of CD14^+ cells

Objective:Inflammasomes promote carcinogenesis through an extrinsic pathway and maintain the malignant cancer microenvironment through an intrinsic pathway.Moreover,inflammasomes exert anticancer effects by pyroptosis and immune regulatory functions.Until now,there have been few studies about how inflammasomes contribute to hepatocellular carcinoma(HCC)development.

Lymph node metastasis of hepatocellular carcinoma is associated with gut microbiota, bile acid metabolism and inflammation

Objective:Hepatocellular carcinoma(HCC)is the most common primary liver cancer and is the second leading cause of cancer-related death globally.Lymph node metastasis(LNM)is negatively correlated with prognosis of HCC patients.The gut microbiota has an important role in development and progression of HCC.In this study.

揭示硫掺杂的碳材料在水电氧化过程中活性苯醌基团及惰性硫残留物的形成

杂原子掺杂的碳材料具有成本低、导电性高、耐酸碱性强等优点,被直接或作为载体材料广泛应用于各类电催化反应.由于杂原子和碳原子之间的电负性差异很大,人们通常将杂原子掺杂的碳材料析氧(OER)活性提高的原因归于杂原子诱导的碳原子上电荷的重新分布.然而,硫(2.58)与碳(2.55)的电负性几乎相同,说明硫掺杂不会导致碳上显著的电荷重新分布.因此,硫掺杂碳材料的活性来源可能与其他元素掺杂的碳材料不同.目前,部分研究表明,硫掺杂是通过改变碳基体的自旋密度而非电荷密度来优化反应活性.还有一些研究将活性的增强归因于硫掺杂的碳材料中存在的硫杂环结构.然而,上述结论都是基于硫掺杂碳材料本身可以在电催化中保持稳定这一前提下提出的,材料本身电催化过程中可能发生的结构和组分转变,尤其是在强氧化OER条件下发生的转变被忽略了.硫杂环是一种具有还原性的硫物种,在强氧化的OER条件下应当同样发生氧化.因此,硫掺杂的碳材料及其作为金属材料的载体在催化OER时的活性起源和催化机制仍然不明确.本文研究了硫掺杂的石墨薄片(S-GP)在碱性OER过程中的活化以及相应的结构演化过程.连续的电化学线性扫描结果表明,S-GP可以在OER过程中发生活化.将线性扫描曲线用电化学活性面积归一化后活化现象依然明显,说明活性的增强来源于本征催化活性的提高,而不是活性面积的增加.此外,活化后S-GP还表现出更快的反应动力学,更小的电荷转移电阻,以及较好的稳定性,即当电流密度达到100 m Acm^(-2)时至少可以稳定运行30 h.X射线能谱(EDS)、X射线光电子能谱(XPS)、软X射线吸收光谱(XAS)以及拉曼光谱结果表明,S-GP在催化OER过程中发生了氧化,形成了大量含氧官能团,并且其中部分掺杂的硫也发生氧化并以SO_(4)^(2-)的形式溶出.通过添加额外的硫酸盐以及重新更新电解液以除去其中的SO_(4)^(2-)并不能使OER性能发生改变,表明溶解的SO_(4)^(2-)对碳材料的OER不起作用.为了分辨电催化活性究竟是来源于残留的硫物种还是新产生的含氧官能团,对样品采用高温H_(2)煅烧以除去其中的硫和氧.尽管煅烧后的样品OER活性很差,但是连续的线扫能够使它的催化活性快速恢复到煅烧前的水平,表明残留的硫物种对OER是惰性的,而在线扫过程中重新生成的含氧官能团才是真正的OER活性物种.为进一步确定哪一种含氧官能团具有OER活性,结合XPS、softXAS、电位依赖的原位衰减全反射-傅里叶变换红外光谱(ATR-FTIR)、循环伏安法(CV)和C=O基团选择性阻断实验,最终证实苯醌基团是真正的OER活性位点.还发现当硫掺杂的碳材料作为基底与Ni(OH)_(2)复合时,同样会发生类似的转化,并且其中溶出的SO_(4)^(2-)还能对所负载的Ni(OH)_(2)的OER活性起到促进作用.综上,本文不仅阐明了硫掺杂的碳自身及其作为金属材料的载体在电催化析氧反应中的催化机制和活性起源,而且能够推动研究者重新考虑硫掺杂碳材料在其它电催化反应中的反应机制.

Technetium-99m-labeled annexin V imaging for detecting prosthetic joint infection in a rabbit model

Accurate and timely diagnosis of prosthetic joint infection is essential to initiate early treatment and achieve a favorable outcome. In this study, we used a rabbit model to assess the feasibility of technetium-99m-labeled annexin V for detecting prosthetic joint infection. Right knee arthroplasty was performed on 24 New Zealand rabbits. After surgery, methicillin-susceptible Staphylococcus aureus was intra-articularly injected to create a model of prosthetic joint infection （the infected group, n = 12）. Rabbits in the control group were injected with sterile saline （n= 12）. Seven and 21 days after surgery, technetium-99m-labeled annexin V imaging was per- formed in 6 rabbits of each group. Images were acquired 1 and 4 hours after injection of technetium-99m- labeled annexin V （150 MBq）. The operated-to-normal-knee activity ratios were calculated for quantitative ana- lysis. Seven days after surgery, increased technetium-99m-labeled annexin V uptake was observed in all cases. However, at 21 days a notable decrease was found in the control group, but not in the infected group. The operated-to-normal-knee activity ratios of the infected group were 1.84 ±0.29 in the early phase and 2.19 ±0.34 in the delay phase, both of which were significantly higher than those of the control group （P=0.03 and P=0.02）. The receiver operator characteristic curve analysis showed that the operated-to-normal-knee activity ratios of the delay phase at 21 days was the best indicator, with an accuracy of 80%. In conclusion, technetium- 99m-labeled annexin V imaging could effectively distinguish an infected prosthetic joint from an uninfected prosthetic joint in a rabbit model.

Serum CA125, CA199, CEA, CA724, and AFP for diagnosis and prognosis prediction in patients with intrahepatic cholangiocarcinoma

Objective:Intrahepatic cholangiocarcinoma(ICC)is a malignancy that involves difficulties in early diagnosis and has extremely poor prognosis.This study aimed to evaluate serum carbohydrate antigen 125(CA125),serum carbohydrate antigen 199(CA199),carcinoembryonic antigen(CEA),carbohydrate antigen 724(CA724)and alpha-fetoprotein(AFP)as biomarkers for diagnosis and prognosis of ICC patients.

Exploratory study of highly susceptible to SARS-CoV-2 populations

The coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),is threatening public health.The human angiotensin-converting enzyme 2(ACE2)has a remarkably high affinity binding to SARS-CoV-2.This study explored whether certain populations,including obese and cancer patients,are susceptible to SARS-CoV-2.The expression pattern of ACE2 in normal and tumor tissues of cancer patients was compared by the search for network database and re-analysis of pubic data.The level of ACE2 expression in normal adipose tissue was higher than that in normal lung tissue,which indicated the adipose tissue might be vulnerable to SARS-CoV-2;the levels of ACE2 expressed by adipocytes and adipose progenitor cells were similar between non-obese individuals and obese individuals(BMI>29),but obese individuals have more adiposes so as to increase the number of ACE2-expressing cells;the expression of ACE2 in tumor tissues posed by five different types of cancers increased significantly compared with that in adjacent tissues.Therefore,we proposed the following hypothesis:the obese individuals and five types of cancer patients might have a higher risk of SARS-CoV-2 infection,which might become the target population of SARS-CoV-2 infection in the future.

Analysis of the Spatio-Temporal Characteristics of Winter Surface Urban Heat Island:A Case Study in Beijing,China

This study reveals the temporal and spatial evolution characteristics of the winter nighttime urban heat island(UHI)effect in the case of Beijing,China.The land surface temperature(LST)is retrieved by radiative transfer equation by using the remote sensing data from Landsat ETM+/OLI_TIRS from 2007 to 2017 for the winter nighttime period,and LST is then divided by the mean-standard deviation method into different levels of thermal landscapes.A combination of the migration calculation of gravity center and multi-directional profile analysis is used to study the directional differentiation characteristics of LST and the migratory characteristics of the gravity center of UHI.Finally,the overall temporal and spatial evolution characteristics of winter nighttime surface urban heat island(SUHI)in Beijing are studied,and the possible reasons for the changes are discussed.Results show that Beijing's UHI effect first increased and subsequently decreased from 2007 to 2017.The winter heat island in the urban area developed from low-density agglomeration to high-density agglomeration to lowdensity diffusion.Additionally,the high-level thermal landscapes migrated to the southwest along with the city center of gravity,and the expansion rate is fastest in the southwest,which is directly linked to the changes in the urban construction land.Moreover,the overall spatial distribution of winter nighttime LST is high in the east and south and low in the west and north,and is influenced by topography,land cover,urbanization,anthropogenic heat,and other factors as well.

PKCαphosphorylation of GLT-1 at Ser562/563 induces glutamate excitotoxicity in ischemia in mice

Dear Editor,Glutamate excitotoxicity due to its accumulation in the extracellular space is a major factor to the brain damage that occurs during the early stages of cerebral ischemia1.GLT-1 is mainly expressed in astrocytes,and it is responsible for almost 90%of glutamate uptake in the brain2.Although GLT-1 upregulation under the administration of ceftriaxone reduces ischemic brain damage,translational application of ceftriaxone in acute ischemia treatment is limited because several days are needed for the upregulation of GLT-1^(3),which misses the critical time window during which suppression of excitotoxicity will be effective.

Study on the anaphylactic shock induced by hemocoagulase for injection based on logistic analysis

In the present study, we aimed to explore the influencing factors of anaphylactic shock caused by hemocoagulase for injection and to provide a scientific basis for clinical safe medication. The cases reports on the adverse reactions induced by hemocoagulase for injection were collected in Chinese and foreign literatures. The clinical characteristics and influencing factors of anaphylactic shock induced by hemocoagulase for injection were evaluated by logistic regression analysis. In this study, 87 articles including 108 cases(68 cases of anaphylactic shock) were collected. Univariate logistic regression indicated that allergic constitution, daily dose, combined anesthesia, first drug delivery, post-dose time and course of treatment were positively associated with the incidence of anaphylactic shock caused by hemocoagulase for injection(P<0.05). The six above-mentioned factors were included in the multivariate logistic stepwise regression analysis to exclude the effects of confounding factors, and the results suggested that allergic constitution(P = 0.048, OR = 8.242), combined anesthesia(P = 0.024, OR = 22.675) and post-dose time(P = 0.006, OR = 20.255) were associated with the incidence of anaphylactic shock caused by hemocoagulase for injection. The clinicians should pay much more attention to risk factors that may cause anaphylactic shock, such as allergic constitution, combined anesthesia and post-dose time. The clinical pharmacists should strengthen pharmaceutical monitoring and improve the safety of medication.

A clinicopathological study of 39 cases of atypical polypoid adenomyoma of the uterus

Objective:To clarify the clinical and pathological characteristics of atypical polypoid adenomyoma(APA)in order to improve the criteria used to diagnose and treat this disease.Study design:In 39 cases of APA,retrospective analysis was performed of theclinical data,pathological characteristics,and the follow-up findings in patients admitted to the Peking University People's Hospital from 2007 to 2019.Results:The median age was 39.6 years(range 24–60 years).Thirty seven patients were premenopausal(i.e.94.9%)and eighteen patients were nullipara(i.e.46.2%).Abnormal uterine bleeding was the most common presenting symptom.Hysteroscopic transcervical resection(i.e.TCR)identified lesions in 35 cases whereas:(a)hysterectomy identified them in 3 cases;(b)dilatation and curettage(D&C)identified them in 1 case.Immunohistochemical analysis was performed on 24 samples.In the glandular component,hormone receptors were positively expressed.In all cases,Ki67 expression was detectable in approximately 50%of the cases.In those samples,its presence was definitive in eighteen of the nineteen cases(94.7%,18/19),p53 positive expression was present in most cases(68.8%,11/16),and PTEN positive expression was detected in 40%(4/10).Stroma immunophenotype expression was exhibited as follows:(a)CD10-(12/12),Desminþ(6/7);(b)Vimentinþ(4/4);(c)α-SMAþ(3/3)and;d p16 positve staining in of 80%(4/5).The concurrent amount of atypical endometrial hyperplasia with atypical polypoid adenomyoma was 23.1%(9/39),while its concurrent level of endometrial carcinoma with atypical polypoid adenomyoma was 7.7%(3/39).Fertility preserving treatments were performed in 20 patients with strong childbearing desires.Their pregnancy success was 15%(3/20)and the live birth frequency was 10%(2/10).Follow-up findings were available in 36 cases(92.3%)with a medial follow-up of 48.1 months(range 4–122 months).Its pathological recurrence and frequency of progression into endometrial carcinoma were both 5%(1/20).One case died of another type of malignancy,while the other patients were alive.Conclusions:APA occurs mostly during the years of a women's reproductive period.Its diagnosis is based on the analysis of pathological and immunohistochemical findings.Individuals diagnosed with APA are at risk to coexist with endometrial carcinoma and atypical endometrial hyperplasia.For those individuals who desire retaining fertility,the treatment strategy involves performing TCR completely remove the lesions and close follow-up for surveillance of possible progressive APA recurrence.For those individuals who have no fertility desire,hysterectomy may be a preferred option.

Buildup of Sn@CNT nanorods by in-situ thermal plasma and the electronic transport behaviors

Monocrystal Sn nanorods encapsulated in the multi-walled carbon nanotubes(Sn@CNT NRs), were fabricated by a facile arc-discharge plasma process, using bulk Sn as the raw target and methane as the gaseous carbon source. The typical Sn@CNT NRs are 40–90 nm in diameter and400–500 nm in length. The CNTs protect the inner Sn nanorods from oxidation. Temperature dependent I–V curve and electronic resistance reveal that the dielectric behavior of Sn@CNT NRs is attributed to the multi-wall CNTs shell and follows Mott-David variable range hopping [ln R(T)∝T-1/4]model above the superconducting critical temperature of3.69 K, with semiconductor–superconductor transition(SST).Josephson junction of Sn/CNT/Sn layered structure is responsible for the superconducting behavior of Sn@CNT NRs.

The characteristics and implications of epidemic reports during COVID-19 in the United States

We summarized the basic practices and characteristics of epidemic reporting during the COVID-19 pandemic in the United States.Based on the analysis of the advantages and disadvantages of epidemic data reporting,we put forward some suggestions that should be used for reference and thus improve the epidemic data reports of infectious diseases.