一流课程视域下的高等师范院校有机化学课程建设与实践

为有效提升师范院校有机化学课程教学质量,针对我院有机化学课程建设中存在的问题,基于“学生中心、出口导向、持续改进”理念,从学生学习和教师教学两个层面进行了剖析;并针对性提出问题解决思路,阐述了课程建设实施的“一二八”战略,构建了特色鲜明、成效显著的有机化学课程教学体系,课程建设取得了明显成效。

Characterizing permeability-porosity relationships of porous rocks using a stress sensitivity model in consideration of elastic-structural deformation and tortuosity sensitivity

Clarifying the relationship between stress sensitivities of permeability and porosity is of great significance in guiding underground resource mining.More and more studies focus on how to construct stress sensitivity models to describe the relationship and obtain a comprehensive stress sensitivity of porous rock.However,the limitations of elastic deformation calculation and incompleteness of considered tortuosity sensitivity lead to the fact that the existing stress sensitivity models are still unsatisfactory in terms of accuracy and generalization.Therefore,a more accurate and generic stress sensitivity model considering elastic-structural deformation of capillary cross-section and tortuosity sensitivity is proposed in this paper.The elastic deformation is derived from the fractal scaling model and Hooke's law.Considering the effects of elastic-structural deformation on tortuosity sensitivity,an empirical formula is proposed,and the conditions for its applicability are clarified.The predictive performance of the proposed model for the permeability-porosity relationships is validated in several sets of publicly available experimental data.These experimental data are from different rocks under different pressure cycles.The mean and standard deviation of relative errors of predicted stress sensitivity with respect to experimental data are 2.63%and 1.91%.Compared with other models,the proposed model has higher accuracy and better predictive generalization performance.It is also found that the porosity sensitivity exponent a,which can describe permeability-porosity relationships,is 2 when only elastic deformation is considered.a decreases from 2 when structural deformation is also considered.In addition,a may be greater than 3 due to the increase in tortuosity sensitivity when tortuosity sensitivity is considered even if the rock is not fractured.

Iterative FEA Method for Load Distribution of Flexible Supporting Thin-section Ball Bearing

To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution's influence on bearing life,an iterative FEA method is proposed to use the result calculated from the Quasi-Dynamic model based on the rigid support hypothesis. The contact angle,contact position and stiffness of equivalent spring are modified during the iterative FEA to optimize the FEA model,and then the bearings' life can be predicted when the error is below 0.5%. It can be concluded that from the analysis results the load distribution under flexible support is more uniform than that of the rigid support,while the maximum load decreases by 11.2% and bearing life increases by 14.7%. The analysis result of different values of thickness of bearing house,rings and hollow shaft demonstrates the thicknesses of bearing house and hollow shaft have a greater influence on the load's uniformity and bearing's life than those of the rings.

The Pathogenicity of Chicken Pathogenic <i>Escherichia coli</i>Is Associated with the Numbers and Combination Patterns of Virulence-Associated Genes

Various virulence-associated genes or pathogenicity island are responsible for determining the pathogenicity of Escherichia coli strains. However, the correlation of the number and combination patterns of virulence-associated genes in Escherichia coli strains with their pathogenicity remains largely unknown. In this work, 581 chicken Escherichia coli strains were isolated from 1045 liver samples of dead chickens from 50 chicken farms at four provinces in China during 2007-2012. Based on the pathogenic test of SPF chickens, 320 chickens pathogenic Escherichia coli isolates were identified as highly (n = 193), intermediate (n = 98) and low pathogenic (n = 29) strains, respectively. Furthermore, the number of virulence genes in the 320 chicken pathogenic and 50 non-pathogenic Escherichia coli strains was examined. Our results reveal that thirteen virulence genes in Escherichia coli strains were detected, and all strains carried at least two or more than two virulence-associated genes. This study also suggests that highly pathogenic E. coli strains simultaneously carried at least 8 to13 virulence genes while intermediate pathogenic strains carried at least 5 to 8 virulence genes. The number of virulence-associated genes detected in highly pathogenic strains showed there were more significant differences than that in low pathogenic strains (P irp2, fyuA, and colV in high pathogenic strains was significantly higher than that in low and non-pathogenic strains (P irp2, fyuA, iucA, iucD, iutA, papC, iss, tsh, and colV were more often detected in highly and intermediate pathogenic E. coli strains. Taken together, our results provide evidences demonstrating that the pathogenicity of Escherichia coli strains is closely associated with the number and combination patterns of virulence-associated genes.

Synchronization of Estrus in Sheep in Different Seasons

[Objectives] The aim was to improve and stabilize the estrus synchronization of local sheep in Xinjiang during the breeding season and non-breeding season. [Methods]The data of estrus rate and estrus concentration time were analyzed by different hormone treatment programs. [Results]eding season,whether PMSC was used did not affect the estrus of sheep when sponge and PG were used（ P 〉 0. 05）. Estrus was concentrated in 36-48 h after sponge plugs were removed,and the estrus rate in this period accounted for 74. 19% of the total. In non-breeding season,the estrus rate in the sponge plug plus PGF treatment was only56. 12%,significantly lower than that（ 90. 43%） in the sponge plug plus PG plus PMSG treatment（ P 〈 0. 01）. The estrus was also concentrated in 36-48 h after sponge plugs were removed. The estrus rate at this stage was 67. 42%,accounting for 82. 8% of the total. In breeding season,the estrus rate in sheep injected with333 IU of PMSG（ 81. 96%） was significantly lower than those of sheep injected with 500（ 90. 25%） and 750 IU（ 95. 3%）（ P 〈 0. 05）. [Conclusions] This study provides a theoretical basis for the production enterprises to save a lot of manpower and material resources.

Research on Industrial Tourism-led Dabancheng Wind Farm Area Development in Xinjiang Region

Industrial tourism has become a new hot spot for tourism development at home and abroad, but there is still no clean energy industry tourism in Xinjiang. Combined with dabancheng scenic spots planning cases, this paper analyze the conditions for the comprehensive development, the overall concept and industrial tourism products design and other aspects, which draw conclusions that integrated area planning should highlight the characteristics, focus on the aspects of comprehensive development, market positioning and other in-depth study.

Flavonoid from the twigs and leaves of Erythrina variegata

In the present study,17 flavonoids,including 9 prenylated isoflavones,4 isoflavones,3 flavanones and 1 flavone,were isolated from the twigs and leaves of Erythrina variegata.By NMR spectroscopic means and comparision with the data in the leteratures,their structures were elucidated to be euchrenone b10(1),senegalensin(2),erythrinin C(3),scandenone(4),osajin(5),alpinum isoflavone(6),isoerysenegalensein E(7),erysenegalensein E(8),diprenylgenistein(9),abyssinone V(10),abyssinone V 4′-methyl ether(11),4′,7-dihydroxyflavanone(12),3′,5,7-trihydroxy-4′-methoxyisoflavone(13),2′,4′,5,7-tetrahydroxyisoflavone(14),genistein(15),daidzein(16),and apigenin(17).Except for compounds 1,4-7,and 9-10,other compounds were isolated from E.variegata for the first time.

Development and performance evaluation of a culture-independent nanopore amplicon-based sequencing method for accurate typing and antimicrobial resistance profiling in Neisseria gonorrhoeae

Dear Editor,Bacterial antimicrobial resistance(AMR)poses a serious threat to global human health(Antimicrobial Resistance Collaborators,2022).Comprehensive profiling of AMR and accurate molecular typing are important for tracking and controlling the emergence and dissemination of antibiotic-resistant bacteria(Yahara et al.,2021).We previously developed a multiplex amplicon sequencing-based method for directly sequencing AMR-related loci in N.gonorrhoeae from clinical samples(Zhang et al.,2021).

Thermal shock of subsurface material with plastic flow during scuffing

The thermal shock of subsurface material with shear instability and severe plastic flow during scuffing was investigated.The scuffing damage of M50 steel was tested using a high-speed rolling-sliding contact test rig,and the transient temperature during scuffing was calculated using the Fourier transform method considering the effects of both frictional heat and plastic work.The results show that a thermal shock with a rapid rise and subsequent rapid decrease in the contact temperature is generated in the subsurface layers.The frictional power intensity generates a high temperature rise,leading to the austenitization of the subsurface material.Consequently,the plastic flow is generated in the subsurface layer under the high shear stress,and the resulting plastic strain energy generates a further temperature increase.Subsequently,a rapid decrease in the contact temperature quenches the material,resulting in clear shear slip bands and retained austenite in the subsurface layers of the M50 steel.

A multiplex method for detection of SARS-CoV-2 variants based on MALDI-TOF mass spectrometry

The recent outbreak of the coronavirus disease 2019(COVID-19)pandemic and the continuous evolution of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)have highlighted the significance of new detection methods for global monitoring and prevention.Although quantitative reverse transcription PCR(RT-qPCR),the current gold standard for diagnosis,performs excellently in genetic testing,its multiplexing capability is limited because of the signal crosstalk of various fluorophores.Herein,we present a highly effi-cient platform which combines 17-plex assays with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS),enabling the targeting of 14 different mutation sites of the spike gene.Diagnosis using a set of 324 nasopharyngeal swabs or sputum clinical samples with SARS-CoV-2 MS method was identical to that with the RT-qPCR.The detection consistency of mutation sites was 97.9%(47/48)com-pared to Sanger sequencing without cross-reaction with other respiratory-related pathogens.Therefore,the MS method is highly potent to track and assess SARS-CoV-2 changes in a timely manner,thereby aiding the continuous response to viral variation and prevention of further transmission.

Chemical constituents from the the twigs and leaves of Caesalpinia enneaphylla

Fifteen compounds were isolated from the twigs and leaves of Caesalpiniaenneaphylla. Their structures were identified to be: (E)-3-(4-hydroxybenzylidene)- 5,7-dihydroxychroman-4-one (1), 8-methoxybonducellin (2), (E)-3-(3,4- dihydroxybenzylidene)-5,7-hydroxychroman-4-one (3), 2′,4′-dihydroxychalcone (4), oxyfadichalcone B (5), 7-hydroxyflavonone (6), pinocembrin (7), kaempferol (8), quercitrin (9), kaempferol 3-O-α-L-rhamnopyranoside (10), quercetin 3-O-α-D-arabinoside (11), trans-2,3-diacetoxy-1-[(benzoyloxy)methyl]-cyclohexa-4,6-diene (12), 3-hydroxybenzyl benzoate (13), 2-acetoxybenzyl benzoate (14), and glutinol (15). All the compounds were isolated from C. enneaphylla for the first time.

Hierarchical flower-like spinel manganese-based oxide nanosheets for high-performance lithium ion battery

Hierarchical flower-structured two-dimensional(2 D)nanosheet is favorable for electrochemical reactions.The unique structure not only exposes the maximized active sites and shortens ion/electron diffusion channels,but also inhibits the structural strain during cycling processes.Herein,we report the hierarchical flower-like pure spinel manganese-based oxide nanosheets synthesized via a template-orientated strategy.The oriented template is fabricated by decomposition of carbonate obtained from"bubble reaction",via an alcoholassisted hydrothermal process.The resultant spinel manganese-based oxide nanosheets simultaneously possess excellent rate capability and cycling stability.The high-voltage LiNi0.5Mn1.5O4(LNMO-HF)has a uniform phase distribution without the common impurity phase LixNi1-xO2 and NixO.Besides,the LNMO-HF delivers high discharge capacity of142.6 mA h g-with specific energy density of 660.7 W h kg 1 at 1 C under 55℃.More importantly,the template-orientated strategy can be extended to the synthesis of LiMn2 O4(LMO),which can achieve 88.12%capacity retention after 1000 cycles.

Biochar mitigates the biotoxicity of heavy metals in livestock manure during composting

The addition of biochar could mitigate the bioavailability of heavy metals during livestock manure composting.However,the main action mechanism of biochar,such as how it worked,was ambiguous.Therefore,in this study,materials(biochar,alkali modified biochar,pretreated cotton ball)were added by embedding with nylon mesh bags to explore the adsorption performance of added materials and its influence on the composting process.The results showed that embedded materials promoted the formation of humic acid and reduced the distribution proportion of bioavailable fraction of heavy metals during composting(Cu:at least 15.72%;Zn:at least 33.44%).The surface of biochar extracted from composting contained attachments,however,the attachment of heavy metal was not detected and functional groups on the materials did no change significantly.This indicated that the addition of biochar did not directly adsorb heavy metals.Most notably,the microbial network changed after embedding materials,and the succession of microbial community promoted the formation of humic acid.Ultimately,structural equation models verified that embedded materials promoted the formation of humic acid through stable microbial groups,thereby accelerating the passivation of heavy metals during composting.This study provides theoretical and technical supports for mitigating the biotoxicity of heavy metals by biochar during composting.

Modeling the frictional torque of a dry-lubricated tapered roller bearing considering the roller skewing

In this paper, an equation for the calculation of the frictional torque of a dry-lubricated tapered roller bearing(TRB) is provided in which the effect of the roller skewing is emphasized. Calculations were performed to investigate the effect of the roller skewing on the torque of dry-lubricated TRB for two representative preload methods, that is, axial force preload and axial displacement preload. The results show that a proper roller skewing angle under axial force preload benefits the reduction of the TRB torque. However, the roller skewing angle should not exceed a certain critical value;otherwise, it will cause a steep rise in the TRB torque. Finally, the critical value of the roller skewing angle as a function of the friction coefficient and cage pocket clearance is presented. The developed torque model provides a tool for the internal design and torque optimization of dry-lubricated TRBs.

Insights into in-situ TiB/dual-phase Ti alloy interface and its high load-bearing capacity

To better understand the strengthening mechanism of in-situ formed TiB reinforcements in dual-phase Ti6 Al4 V alloy,the interface characters and properties ofα-Ti/β-Ti/TiB system were thoroughly investigated with the combined use of high-resolution transmission electron microscopy(HRTEM),abinitio calculations,and indentation tests.The ab-initio calculations suggest that the highly coherent(100)_(TiB)/(121)_(β-Ti)phase boundary(PB)has fairly low interface energy of 0.082 J/m^(2)with an exceptionally high adhesion strength of 6.04 J/m^(2),owing to the formation of strong interfacial Ti–B ionic bonds.The semi-coherent(201)_(TiB)/(0001)_(α-Ti)interface shows a relatively higher interface energy of 1.442 J/m^(2)but still with a fairly high adhesion strength of 4.95 J/m^(2).With the obtained interfacial energetics,thermodynamics analyses were further carried out to explore the nucleation mechanism ofα-Ti in TiB reinforced Ti6Al4V composite.Superior to the heterogeneous nucleation at TiB/β-Ti interface,the homogeneous nucleation ofα-Ti within theβ-Ti phase can be more energy-preferred,due to its lower nucleation energy barrier and critical radius.Further indentation tests under various loads of different modes confirmed a remarkably enhanced load-bearing capacity of dual-phase Ti6Al4V alloys,under the critical significance of the strong interfacial bonding achieved by reinforcements of in-situ formed TiB.

Taking advantage of drug resistance, a new approach in the war on cancer

Identification of the driver mutations in cancer has resulted in the development of a new category of molecularly targeted anti-cancer drugs. However, as was the case with conventional chemotherapies, the effectiveness of these drugs is limited by the emergence of drug-resistant variants. While most cancer therapies are given in combinations that are designed to avoid drug resistance, we discuss here therapeutic approaches that take advantage of the changes in cancer cells that arise upon development of drug resistance. This approach is based on notion that drug resistance comes at a fitness cost to the cancer cell that can be exploited for therapeutic benefit. We discuss the development of sequential drug therapies in which the first therapy is not given with curative intent, but to induce a major new sensitivity that can be targeted with a second drug that selectively targets the acquired vulnerability. This concept of collateral sensitivity has hitherto not been used on a large scale in the clinic and holds great promise for future cancer therapy.

The effect of whey protein on viral infection and replication of SARS-CoV-2 and pangolin coronavirus in vitro

Dear Editor,Since severe acute respiratory syndrome coronavirus 2(SARSCoV-2)RNA has been detected in human breastmilk,infants’safety with breastmilk feeding is of great concern for women with coronavirus disease 2019(COVID-19).1 It is known that milk has antiviral properties.2 However,little is known about the antiviral property of human breastmilk to SARS-CoV-2 and its related pangolin coronavirus(GX_P2V).Here we present for the first time that whey protein from human breastmilk effectively inhibited both SARS-CoV-2 and GX_P2V by blocking viral attachment and viral replication at entry and even post entry.Moreover,human whey protein inhibited infectious virus production,as proved by the plaque assay.We found that whey protein from different species,such as cow and goat,also showed anti-coronavirus properties.Commercial bovine formula milk also showed similar anti-SARS-CoV-2 activity.

High impact of vehicle and solvent emission on the ambient volatile organic compounds in a major city of northwest China

Monitoring of ambient volatile organic compounds(VOCs)was conducted within typical residentialcommercial area in the city of Xi’an in northwest China during typical ozone(O_(3))episodes,to investigate the major contributors to the characteristic of ambient VOCs and their impact on O_(3) production.In the residential-commercial area,diurnal variation of VOCs was highly impacted by vehicle exhaust,fuel evaporation,and local solvent use.Relative higher contributions(up to 60%)of VOCs from solvent use to the ozone formation potential were found.The present findings highlight the urgent need for restrictions on the emission of VOCs from solvent use and non-vehicle-traffic-related sources,such as oil storage.

Effects and mechanism of freeze-thawing cycles on the soil N2O fluxes in the temperate semi-arid steppe

High nitrous oxide （N20） emissions during freeze-thawing period （FFP） have been observed in many different ecosystems. However, the knowledge about the dynamic of soil N20 emissions and its main driving mechanism during the freeze-thawing processes in grassland ecosystem is still limited. An in-situ experiment was conducted during the FTP on the sites with 0 and 15% surplus of the average rainfall and two levels of N addition （0,10 g N/（m2-year）） during growing season （marked as WON0, WISN0, WONI0, WISNI0, respectively） to explore the effects of water and N background on soil N20 emissions during FTPs and the relationship between soil N20 emissions and environmental factors. The results indicated that water and N treatments conducted during growing season did not show significant effect on the N20 effluxes of FTP, but the soil mineral N contents of WONI0 treatment were significantly higher than those of WON0, WI5N0, WI5NI0 treatments （p 〈 0.05）. The soil PLFA concentrations of microbial groups monitored during 2015 spring freeze-thawing period （2015S-FTP） were lower than those during winter freeze-thawing period of 2014 （2014W-FTP）, while cumulative soil N20 emissions of 2015S-FTP were higher than those of 2014W-FFP. The correlations between soil N20 effluxes and most of the measured environmental factors were insignificant, multiple stepwise regression analysis indicated that the soil temperature, soil NH$-N content and air temperature were the major environmental factors which significantly influenced the N20 effluxes during 2014W-FTP, and air temperature and son water content were the significant influencing factors during 2015S-FTP.

Thermal analysis of lubricated three-dimensional contact bodies considering interface roughness

Surface roughness and thermal action are of remarkable importance in the lubrication performance of mechanical components,especially in extreme conditions.However,available studies mainly focus on the full-film lubrication conditions without considering temperature rise and real 3D surface roughness due to the complexity of surface topography and temperature characteristics.Moreover,studies on the interfacial thermal behaviors of 3D rough surface lubricated contact in an extended range of working conditions remain limited.In this paper,a deterministic mixed thermal elastohydrodynamic lubrication model considering real 3D surface roughness and thermal effects is proposed.In this model,pressure and temperature are coupled with each other,the computation of elastic deformation is accelerated through the discrete convolution and fast Fourier transform method,the temperature field is calculated with the column sweeping technique,and the semi-system method is introduced to improve convergence and numerical stability under severe conditions.The model is validated by comparing its results with available published numerical and experimental results.The thermal behaviors of the contact interface are studied in a wide range of working conditions.The influences of surface roughness and thermal effect on lubrication performance are revealed.The results show that the proposed model can be used as a powerful analysis tool for lubrication performance and temperature prediction in various heavy-load,high-speed lubricated components over a wide range of lubrication conditions.