美国科学教育研究资助体系分析及其启示

加强科学教育是推进教育、科技、人才“三位一体”的统筹部署和实现科技创新自立自强的基础性工程。虽然科学教育已经在政策和实践层面备受关注,且已取得明显进展,我国科学教育依然面临着诸多的挑战与不足,其关键原因之一是支撑科学教育高质量发展的科学教育研究资助体系的缺乏。鉴于美国在科学教育研究领域的引领地位及其形成的完善的研究资助格局,本文全面介绍了美国科学教育研究资助体系的概况,深入分析了以美国国家科学基金会为代表的联邦政府机构对于科学教育的资助布局及其对K-12教育阶段的资助计划,形成了对于建立我国科学教育研究资助体系的建议。

铝板水热碳吸附工艺制备APC/Al层状复合材料的显微组织、力学性能和摩擦学性能

采用铝板水热碳吸附工艺(HTCAP)和真空热压烧结工艺(VHPS)制备无定形碳(APC)/Al层状复合材料,研究葡萄糖溶液浓度对其显微组织、力学性能和摩擦学性能的影响。结果表明,APC在层间分布均匀,并且通过Al的扩散与基体形成良好的界面结合。随着葡萄糖溶液浓度的增加,层间硬度、极限抗拉强度(UTS)和伸长率先增大后减小,而磨损率则呈现相反的趋势,摩擦因数(COF)逐渐减小。当葡萄糖溶液浓度为0.3 mol/L时,伸长率最大,为16.4%,磨损率最小,为0.344×10^(-5)mm^(3)/(N·m)。粘着磨损是APC/Al层状复合材料的主要磨损机制。耐磨性的提高是由于在磨损表面形成均匀的APC润滑膜。

La/Nd比对AZ91-RE合金显微组织和拉伸性能的影响

研究La/Nd比对AZ91-RE合金显微组织和拉伸性能的影响。采用经典表征方法分析第二相的体积分数、平均最近邻距离(NND)和数量密度。利用第一性原理计算确定第二相的形成焓、力学性能和热力学性质。结果表明,La与Nd的质量分数比(w_(La)/w_(Nd))为3/2的合金具有最小的平均晶粒尺寸、最小的平均最近邻距离和最高的第二相数量密度。计算结果表明,Al_(11)La_(3)和Al2Nd的形成在能量上有利。此外,Al_(11)La_(3)和Al_(2)La在抗变形能力、抗剪切变形能力、固体刚度和热稳定性方面都明显优于其他第二相。因此,提高Al_(11)La_(3)和Al_(2)La相的含量有利于改善AZ91-RE合金的力学性能。

Pectin methylesterase inhibitors GhPMEI53 and AtPMEI19 improve seed germination by modulating cell wall plasticity in cotton and Arabidopsis

The germination process of seeds is influenced by the interplay between two opposing factors,pectin methylesterase(PME)and pectin methylesterase inhibitor(PMEI),which collectively regulate patterns of pectin methylesterification.Despite the recognized importance of pectin methylesterification in seed germination,the specific mechanisms that govern this process remain unclear.In this study,we demonstrated that the overexpression of GhPMEI53is associated with a decrease in PME activity and an increase in pectin methylesterification.This leads to seed cell wall softening,which positively regulates cotton seed germination.AtPMEI19,the homologue in Arabidopsis thaliana,plays a similar role in seed germination to GhPMEI53,indicating a conserved function and mechanism of PMEI in seed germination regulation.Further studies revealed that GhPMEI53 and AtPMEI19 directly contribute to promoting radicle protrusion and seed germination by inducing cell wall softening and reducing mechanical strength.Additionally,the pathways of abscicic acid(ABA)and gibberellin(GA)in the transgenic materials showed significant changes,suggesting that GhPMEI53/AtPMEI19-mediated pectin methylesterification serves as a regulatory signal for the related phytohormones involved in seed germination.In summary,GhPMEI53 and its homologs alter the mechanical properties of cell walls,which influence the mechanical resistance of the endosperm or testa.Moreover,they impact cellular phytohormone pathways(e.g.,ABA and GA)to regulate seed germination.These findings enhance our understanding of pectin methylesterification in cellular morphological dynamics and signaling transduction,and contribute to a more comprehensive understanding of the PME/PMEI gene superfamily in plants.

一种阴离子浸出策略合成金属羟基氧化物用于电催化甘油氧化

亲核氧化反应在可持续生产增值化学品中扮演着重要角色。电催化甘油氧化反应作为亲核氧化反应的一种重要类型,可以制得包括甲酸在内的C_(1)至C_(3)衍生产物。非贵金属氢氧化物/羟基氧化物被广泛应用于甘油氧化反应,但在中等电位下难以达到工业级电流密度(大于300 mA·cm^(-2))。研究表明,氢氧化物/羟基氧化物催化的甘油氧化反应通过间接氧化机理进行,即通过电生成的含有亲电吸附氧的羟基氧化物氧化亲核试剂(甘油)。因此,理解甘油氧化反应中电催化剂的演变至关重要。在本文中,通过循环伏安法活化钼酸镍(NiMoO_(4)),开发了一种钼掺杂的羟基氧化镍(Mo-NiOOH)催化剂。通过多种表征方法对Mo-NiOOH进行了系统表征,结果显示,Mo-NiOOH继承了NiMoO_(4)前驱体的纳米片阵列形貌,但Mo含量降低,证明循环伏安法活化后实现了从氧化物到羟基氧化物的相重构。此外,Mo-NiOOH中Ni^(3+)/Ni^(2+)的比例高于循环伏安法活化制备的NiOOH。在活化过程中,Mo物种从NiMoO_(4)中浸出,制备得到的Mo-NiOOH保留了NiMoO_(4)前驱体的纳米片阵列形貌。与氢氧化镍(Ni(OH)_(2))经循环伏安法活化合成的NiOOH相比,Mo-NiOOH具有更高的Ni^(3+)/Ni^(2+)比例以及更高的电化学比表面积(ECSAs),且促进了Ni^(2+)氧化为Ni^(3+)。因此,Mo-NiOOH达到高电流密度(400mA·cm^(-2))的电位(1.51V vs.RHE)低于NiOOH(1.84 V vs.RHE)。此外,Mo-NiOOH表现出高于NiOOH的甲酸盐法拉第效率(84.7%vs.59.6%),表明钼掺杂加速了碳-碳键断裂。多电位阶跃实验显示,NiOOH和Mo-NiOOH催化的甘油电氧化通过类似的羟基氧化物介导的间接氧化机理进行。原位电化学阻抗谱和原位拉曼光谱证实,Mo掺杂促进了甘油氧化反应动力学以及Ni^(2+)氧化为Ni^(3+)的过程,导致Mo-NiOOH比NiOOH具有更高的活性和甲酸选择性。本研究通过可溶性阴离子浸出策略来调节羟基氧化物表面结构,为设计高性能亲核氧化反应电催化剂提供了指导。

Leveraging Uncertainty for Depth-Aware Hierarchical Text Classification

Hierarchical Text Classification(HTC)aims to match text to hierarchical labels.Existing methods overlook two critical issues:first,some texts cannot be fully matched to leaf node labels and need to be classified to the correct parent node instead of treating leaf nodes as the final classification target.Second,error propagation occurs when a misclassification at a parent node propagates down the hierarchy,ultimately leading to inaccurate predictions at the leaf nodes.To address these limitations,we propose an uncertainty-guided HTC depth-aware model called DepthMatch.Specifically,we design an early stopping strategy with uncertainty to identify incomplete matching between text and labels,classifying them into the corresponding parent node labels.This approach allows us to dynamically determine the classification depth by leveraging evidence to quantify and accumulate uncertainty.Experimental results show that the proposed DepthMatch outperforms recent strong baselines on four commonly used public datasets:WOS(Web of Science),RCV1-V2(Reuters Corpus Volume I),AAPD(Arxiv Academic Paper Dataset),and BGC.Notably,on the BGC dataset,it improvesMicro-F1 andMacro-F1 scores by at least 1.09%and 1.74%,respectively.

Achieving high strength and rapid degradation in Mg-Gd-Ni alloys by regulating LPSO phase morphology combined with extrusion

In this study,Mg-13.2Gd-4.3Ni alloys containing continuous bulk-shaped long-period stacking ordered(LPSO),lamellar LPSO,and a small amount of eutectic phase were prepared,and the evolution of microstructure at different extrusion temperatures and its influence on mechanical and degradation properties as well as corrosion mechanism were investigated.Preheating before extrusion can effectively promote the precipitation of lamellar LPSO in matrix.EX400 with higher volume fraction of non-DRXed grains exhibited higher strength,which was mainly due to strong texture,high dislocation density,and high volume fraction of lamellar LPSO.The EX420 with higher volume fraction of DRXed grains showed higher degradation rate,which was mainly due to the higher density of grain boundary.The EX400 exhibited excellent comprehensive properties with tensile yield strength(TYS)of 334 MPa,ultimate tensile strength(UTS)of 484 MPa and elongation(EL)of 7.4%,ultimate compressive strength(UCS)of 638 MPa and compressive yield strength(CYS)of 443 MPa,degradation rate of 86.1 mg/cm^(2)/h at 93℃in 3 wt.%KCl solution.

Endoscopic and pathological features of neoplastic transformation of gastric hyperplastic polyps:Retrospective study of 4010 cases

BACKGROUND Hyperplastic polyps,which represent 30%-93%of all gastric epithelial polyps,are the second most common type of gastric polyps after fundic gland polyps.They were previously considered to have no risk of neoplastic transformation.Recently,an increasing number of cases of gastric hyperplastic polyps(GHPs)combined with neoplastic changes have been reported;however,the specific mechanism underlying their transformation has not been thoroughly explored.AIM To investigate the clinical,endoscopic,and pathological characteristics of the neoplastic transformation of GHPs and explore the risk factors.METHODS A retrospective analysis was performed on 4010 cases of GHPs diagnosed by gastroscopy and pathological examination at the hospital from 2005 to 2021.In total,3874,119,and 17 cases were in the group without intraepithelial neoplasia(IN),with low-grade IN,and with high-grade IN,respectively.The data analysis examined the association of endoscopic and pathological features with risk factors for neoplastic transformation.Factors with significant differences were entered into univariate logistic regression,followed by multivariate logistic regression analysis.RESULTS Univariate analysis revealed diameter,multiple polyp presence,redness,rough surface,lobulation,erosion,Yamada classification,location,and gastric mucosa were risk factors for neoplastic transformation.Multivariate analysis showed that age>65 years[odds ratio(OR)=1.789;95%confidence interval(CI):1.227-2.609;P=0.003],male sex(OR=1.680;95%CI:1.158-2.438;P=0.006),multiple polyps(OR=1.851;95%CI:1.230-2.784;P=0.003),pedunculated or semi-pedunculated shape(OR=2.722;95%CI:1.689-4.388;P<0.001),and polyp diameter were significantly associated with GHPs that demonstrated neoplastic transformation.Compared with chronic superficial gastritis,autoimmune gastritis,atrophic gastritis,and gastritis with IN were independent risk factors for neoplastic transformation[(OR=2.672;95%CI:1.559-4.579;P<0.001),(OR=1.876;95%CI:1.134-3.103;P=0.014),and(OR=5.299;95%CI:3.173–8.849;P<0.001),respectively].CONCLUSION Male sex,age>65 years,multiple polyps,pedunculated or semi-pedunculated shape,polyp size>1 cm,and specific background gastric mucosa are key indicators for predicting neoplastic transformation of GHPs.

Comprehensive analysis of gene mutations and mismatch repair in Chinese colorectal cancer patients

BACKGROUND RAS,BRAF,and mismatch repair(MMR)/microsatellite instability(MSI)are crucial biomarkers recommended by clinical practice guidelines for colorectal cancer(CRC).However,their characteristics and influencing factors in Chinese patients have not been thoroughly described.AIM To analyze the clinicopathological features of KRAS,NRAS,BRAF,and PIK3CA mutations and the DNA MMR status in CRC.METHODS We enrolled 2271 Chinese CRC patients at the China-Japan Friendship Hospital.MMR proteins were tested using immunohistochemical analysis,and the KRAS/NRAS/BRAF/PIK3CA mutations were determined using quantitative polymerase chain reaction.Microsatellite status was determined using an MSI detection kit.Statistical analyses were conducted using SPSS software and logistic regression.RESULTS The KRAS,NRAS,BRAF,and PIK3CA mutations were detected in 44.6%,3.4%,3.7%,and 3.9% of CRC patients,respectively.KRAS mutations were more likely to occur in patients with moderate-to-high differentiation.BRAF mutations were more likely to occur in patients with right-sided CRC,poorly differentiated,or no perineural invasion.Deficient MMR(dMMR)was detected in 7.9% of all patients and 16.8% of those with mucinous adenocarcinomas.KRAS,NRAS,BRAF,and PIK3CA mutations were detected in 29.6%,1.1%,8.1%,and 22.3% of patients with dMMR,respectively.The dMMR was more likely to occur in patients with a family history of CRC,aged<50 years,right-sided CRC,poorly differentiated histology,no perineural invasion,and with carcinoma in situ,stage I,or stage II tumors.CONCLUSION This study analyzed the molecular profiles of KRAS,NRAS,BRAF,PIK3CA,and MMR/MSI in CRC,identifying key influencing factors,with implications for clinical management of CRC.

Efficacy of laparoscopic low anterior resection for colorectal cancer patients with 3D-vascular reconstruction for left coronary artery preservation

BACKGROUND Laparoscopic low anterior resection(LLAR)has become a mainstream surgical method for the treatment of colorectal cancer,which has shown many advantages in the aspects of surgical trauma and postoperative rehabilitation.However,the effect of surgery on patients'left coronary artery and its vascular reconstruction have not been deeply discussed.With the development of medical imaging technology,3D vascular reconstruction has become an effective means to evaluate the curative effect of surgery.AIM To investigate the clinical value of preoperative 3D vascular reconstruction in LLAR of rectal cancer with the left colic artery(LCA)preserved.METHODS A retrospective cohort study was performed to analyze the clinical data of 146 patients who underwent LLAR for rectal cancer with LCA preservation from January to December 2023 in our hospital.All patients underwent LLAR of rectal cancer with the LCA preserved,and the intraoperative and postoperative data were complete.The patients were divided into a reconstruction group(72 patients)and a nonreconstruction group(74 patients)according to whether 3D vascular reconstruction was performed before surgery.The clinical features,operation conditions,complications,pathological results and postoperative recovery of the two groups were collected and compared.RESULTS A total of 146 patients with rectal cancer were included in the study,including 72 patients in the reconstruction group and 74 patients in the nonreconstruction group.There were 47 males and 25 females in the reconstruction group,aged(59.75±6.2)years,with a body mass index(BMI)(24.1±2.2)kg/m^(2),and 51 males and 23 females in the nonreconstruction group,aged(58.77±6.1)years,with a BMI(23.6±2.7)kg/m^(2).There was no significant difference in the baseline data between the two groups(P>0.05).In the submesenteric artery reconstruction group,35 patients were type Ⅰ,25 patients were type Ⅱ,11 patients were type Ⅲ,and 1 patient was type Ⅳ.There were 37 type Ⅰ patients,24 type Ⅱ patients,12 type Ⅲ patients,and 1 type Ⅳ patient in the nonreconstruction group.There was no significant difference in arterial typing between the two groups(P>0.05).The operation time of the reconstruction group was 162.2±10.8 min,and that of the nonreconstruction group was 197.9±19.1 min.Compared with that of the reconstruction group,the operation time of the two groups was shorter,and the difference was statistically significant(t=13.840,P<0.05).The amount of intraoperative blood loss was 30.4±20.0 mL in the reconstruction group and 61.2±26.4 mL in the nonreconstruction group.The amount of blood loss in the reconstruction group was less than that in the control group,and the difference was statistically significant(t=-7.930,P<0.05).The rates of anastomotic leakage(1.4%vs 1.4%,P=0.984),anastomotic hemorrhage(2.8%vs 4.1%,P=0.672),and postoperative hospital stay(6.8±0.7 d vs 7.0±0.7 d,P=0.141)were not significantly different between the two groups.CONCLUSION Preoperative 3D vascular reconstruction technology can shorten the operation time and reduce the amount of intraoperative blood loss.Preoperative 3D vascular reconstruction is recommended to provide an intraoperative reference for laparoscopic low anterior resection with LCA preservation.

Investigation on the Current Status and Effects of Online Course Learning for Nursing Students

[Objectives]To explore the current situation and effects of online learning from the perspective of students,as well as the learning dynamics,and to explore the online teaching methods.It is possible to put forward relevant suggestions for the problems presented by online teaching,find effective teaching methods,and explore appropriate online teaching methods.[Methods]The nursing students of the 2020,2021,and 2022 grades of Chengde Nursing Vocational College were selected as the research subjects.A self-made questionnaire survey method was adopted.The questionnaire had 5 items and 44 questions:3 questions on personal information,9 questions on the teacher level,12 ques-tions on the student level,7 questions on the technical level,and 13 questions on online learning satisfaction.[Results]In the process of on-line teaching,the cooperation between family and school can be carried out to give full play to the important role of family supervision in online learning and other education,which is conducive to maintaining the discipline of online courses on the Internet,increasing the online learning effect of students,and avoiding the temptation of the Internet to the greatest extent.In the process,we should increase students'self-control in online learning,help students shape realistic goals,and thus improve the effect of online learning.Technical level:increase information-based teaching,enrich teaching content,and introduce virtual simulation software to simulate clinical operations,so as to increase students’interest and enthusiasm in learning.[Conclusions]This study is expected to provide a certain reference for the smooth and efficient development of online teaching and online learning skills.

同质异构Al-Cu-Mg系混晶粉末冶金制备新方法

为突破传统同质粉末材料均以颗粒尺寸细化作为改性的单一途径禁锢,提出同质异构思想,即通过低能球磨将不同粒径的AA2024合金粉末按照一定比例混合,经热压烧结制备混晶坯料。研究结果表明,传统单一粒径粉末烧结后晶粒形貌趋向于不规则多边形状,而不同粒径粉末混合烧结后晶粒形貌为小颗粒包覆大颗粒的结构形式;与前者相比,当粗粉占比为20%(质量分数)时,抗拉强度增加了38.8%;当粗粉占比为50%时,伸长率提高了14%。粉末混合后的烧结样品呈沿晶断裂和穿晶断裂的混合断裂机制,第二相对位错的钉扎效应更加明显,因此,合金性能得到显著提高。此研究工作为高性能同质异构混晶材料的制备提供了一种新思路。

衬板轧制铝/镁/铝复合板的波纹界面结构及形成机理

提出一种采用衬板轧制进行AA1060铝/AZ31B镁/AA1060铝复合板的制备方法。结果表明:传统轧制铝/镁/铝复合板截面轮廓较为平直,而衬板轧制由于衬板可将剪切力部分转化为压应力,从而改变复合板板受力状态,在铝/镁界面连接处形成差速流动,故而界面轮廓呈现波浪状特征,层间实现互锁连接。界面连接强度为64 MPa,是传统轧制复合板的4倍。力学性能测试表明:衬板轧制复合板的抗拉强度可达210 MPa,比传统轧制法提高12.3%。综上可知,衬板轧制法为高性能铝/镁/铝异质复合板成形制造提供一种新思路。

Catalytic conversion of lignocellulosic biomass into chemicals and fuels

In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future,lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a promising feedstock.This review focuses on the state-of-the-art catalytic transformation of lignocellulosic biomass into value-added chemicals and fuels.Following a brief introduction on the structure,major resources and pretreatment methods of lignocellulosic biomass,the catalytic conversion of three main components,i.e.,cellulose,hemicellulose and lignin,into various compounds are comprehensively discussed.Either in separate steps or in one-pot,cellulose and hemicellulose are hydrolyzed into sugars and upgraded into oxygen-containing chemicals such as 5-HMF,furfural,polyols,and organic acids,or even nitrogen-containing chemicals such as amino acids.On the other hand,lignin is first depolymerized into phenols,catechols,guaiacols,aldehydes and ketones,and then further transformed into hydrocarbon fuels,bioplastic precursors and bioactive compounds.The review then introduces the transformations of whole biomass via catalytic gasification,catalytic pyrolysis,as well as emerging strategies.Finally,opportunities,challenges and prospective of woody biomass valorization are highlighted.

Research perspectives for catalytic valorization of biomass

Efficient utilization of biomass for the supply of energy and synthetic materials would mitigate the heavy reliance on fossil resources and the growing CO_(2) emission, thus contributing to establishing sustainable and carbon–neutral societies. Much effort has been devoted to catalytic transformations of lignocellulosic biomass, the most abundant and nonedible form of biomass.

Mechanism of plasticity enhancement of AZ31B magnesium alloy sheet by accumulative alternating back extrusion

Accumulative alternating back extrusion was a potential fine-grain modification method.In this paper,it was an innovative attempt to develop high-performance magnesium alloy sheet by this process.Under the condition of 350 K,commercial AZ31 magnesium alloy was made into billet by accumulative alternating back extrusion,and then extruded into fine-grain magnesium alloy sheet.Through a systematic study of its microstructure and mechanical properties,the results showed that the initial state had an important influence on the evolution of the structure during extrusion.After accumulative alternating back extrusion to produce the billet,the grain size of the sheet obtained by extrusion was significantly refined,which was related to the accumulation of deformation and grain refinement during the alternating loading process.Grain refinement caused the proportion of dynamic recrystallization inside the sheet with 2 cycles of accumulative alternating back extrusion to drop to 27%.With the increase of extrusion cycles from 2 to 4,the high density of dislocations led to an increase in the proportion of dynamic recrystallization and finer grains.The texture changed from strong basal texture to weak bimodal texture.The results of uniaxial tensile test show that due to grain refinement and texture change,the yield strength was significantly reduced,and the plasticity was significantly improved.It was verified that accumulative alternating back extrusion was meaningful for subsequent processing,and it also provided scientific guidance for the development of fine-grained magnesium alloy sheet.

Cs-Induced Phase Transformation of Vanadium Oxide for High-Performance Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries are promising candidate for gridscale energy storage.However,the development of zinc-ion batteries has been plagued by the lack of cathode materials with high specific capacity and superior lifespan.Herein,hexagonal Cs_(0.3)V_(2)O_(5)cathode is fabricated and investigated in zinc-ion batteries.Compared with the traditional vanadium oxides,the introduction of Cs changes the periodic atomic arrangements,which not only stabilizes the open framework structure but also facilitates the Zn^(2+)diffusion with a lower migration energy barrier.Consequently,high specific capacity of 543.8 mA h g^(-1)at 0.1 A g^(-1)is achieved,which surpasses most of reported cathode materials in zinc-ion batteries.The excellent cycle life is achieved over 1000 cycles with about 87.8%capacity retention at 2 A g^(-1).Furthermore,the morphological evolution and energy storage mechanisms are also revealed via a series of techniques.This work opens up a phase engineering strategy to fabricate the hexagonal vanadium oxide and elucidate the application of phase-dependent cathodes in zinc-ion batteries.

Design strategies of performance-enhanced Se cathodes for Li-Se batteries and beyond

Lithium-selenium(Li-Se)batteries are deemed as an emerging high energy density electrochemical energy storage system owing to their high specific capacity and volume capacity.Prior to their practicality,a series of critical challenges from the Se cathode side need to be overcome including low reactivity of bulk Se,shuttle effect of intermediates,sluggish redox kinetics of polyselenides,and volume change etc.In this review,recent progress on design strategies of functional Se cathodes are comprehensively summarized and discussed.Following the significance and key challenges,various efficient functionalized strategies for Se cathodes are presented,encompassing covalent bonding,nanostructure construction,heteroatom doping,component hybridization,and solid solution formation.Specially,the universality of these functional strategies are successfully extended into Na-Se batteries,K-Se batteries,and Mg-Se batteries.At last,a brief summary is made and some perspectives are offered with the goal of guiding future research advances and further exploration of these strategies.

An efficient electrocatalytic system composed of nickel oxide and nitroxyl radical for the oxidation of bio-platform molecules to dicarboxylic acids

Selective oxidation of biomass and its derivatives to dicarboxylic acids represents a promising route for biomass valorization.However,the co-presence of multiple functional groups in biomass molecules makes the selective oxidation of particular functional a challenging task.Here,we demonstrate an efficient electrocatalytic system consisting of nickel oxide(NiO)and a nitroxyl radical,i.e.,2,2,6,6-tetrame thylpiperidine-1-oxyl(TEMPO)or 4-acetamido-TEMPO(ACT),for the selective oxidation of key bioplatform molecules including glucose,xylose and 5-hydroxymethylfurfural(HMF)into corresponding dicarboxylic acids,i.e.,glucaric acid,xylaric acid,and 2,5-furandicarboxylic acid(FDCA).NiO is clarified as the active catalyst for the oxidation of aldehyde in bio-platform molecules to carboxylic acid,while TEMPO or ACT is responsible for the oxidation of primary alcohol to aldehyde.The combination of NiO and TEMPO or ACT significantly accelerated the tandem oxidation of aldehyde and hydroxyl groups in glucose,xylose and HMF,thus achieving excellent yields(83%-99%)of dicarboxylic acids.Moreover,the combination catalyst enables the selective oxidation of glucose and xylose with high concentrations(e.g.,20 wt%),which offers a promising strategy for biomass valorization.

Deep-ultraviolet photonics for the disinfection of SARS-CoV-2 and its variants(Delta and Omicron)in the cryogenic environment

Deep-ultraviolet(DUV)disinfection technology provides an expeditious and efficient way to suppress the transmission of coronavirus disease 2019(COVID-19).However,the influences of viral variants(Delta and Omicron)and low temperatures on the DUV virucidal efficacy are still unknown.Here,we developed a reliable and uniform planar light source comprised of 275-nm light-emitting diodes(LEDs)to investigate the effects of these two unknown factors and delineated the principle behind different disinfection performances.We found the lethal effect of DUV at the same radiation dose was reduced by the cryogenic environment,and a negative-U large-relaxation model was used to explain the difference in view of the photoelectronic nature.The chances were higher in the cryogenic environment for the capture of excited electrons within active genetic molecules back to the initial photo-ionised positions.Additionally,the variant of Omicron required a significantly higher DUV dose to achieve the same virucidal efficacy,and this was thanks to the genetic and proteinic characteristics of the Omicron.The findings in this study are important for human society using DUV disinfection in cold conditions(e.g.,the food cold chain logistics and the open air in winter),and the relevant DUV disinfection suggestion against COVID-19 is provided.