数字革命与大学教学变革——2022世界慕课与在线教育大会分论坛一综述

如何利用教育数字化转型促进教育公平、提高教育质量、实现以人为本的教育是一个新的时代问题。正值中国慕课十年、全面实施教育数字化转型的关键节点,世界慕课与在线教育大会数字革命与大学教学变革分论坛以在线的方式成功举办。文章通过介绍论坛的举办背景、内容安排和专家观点,深入探讨了数字化背景下大学教学发生的深刻变革,围绕“数字化在线教育:新形态与挑战”,介绍了慕课对世界各地的高等教育产生的广泛影响,展望了数字化转型的未来趋势,以及在快速技术变革的背景下教育高质量发展的路径选择;围绕“慕课标准规范:教学实践与经验”,介绍了慕课教学实践取得的丰富经验,展示了慕课标准规范的重要作用和典型案例。最后总结了六点共识:强调教育数字化转型的必然性、凸显慕课在教育教学中的重要价值、关注以学习者为中心的教学、联通教育成为未来发展的趋势、实现更加灵活的个性化教育、更加注重提升教师队伍的水平,并提出共同推进教育数字化转型、创新教育新形态的倡议,以期为我国在线教育的发展与创新提供借鉴。

Experimental and numerical studies of titanium foil/steel explosively welded clad plate

Ti/Fe clad plate had attracted extensive attention because of its important application. In order to reduce the titanium layer thickness, the explosive welding of TA1 titanium foil to Q235 steel plate was carried out. The interfacial bonding performance was analyzed by micromorphology analysis and mechanical property test, and the formation process of interfacial wave and molten block in the vortex was simulated by smoothed particle hydrodynamics(SPH) method. The results showed that salt as pressure transfer layer used in explosive welding could play a good buffer effect on the collision between flyer and base layers. Regular waveforms were formed on the bonding interface, and the titanium foil/steel clad plate exhibited good welding quality and bonding property. The crest of the observed interfacial wave moved 200 μm from the beginning to the final formation, and it was important of jet on the formation of interfacial waveform. The interface was mainly bonded in the form of molten layer, and the grains near the interface were streamlined. Molten block containing intermetallic compounds and metal oxides appeared in the vortex of wave crest.

Change Ratios of Magnetic Helicity and Magnetic Free Energy During Major Solar Flares

Magnetic helicity is an important concept in solar physics,with a number of theoretical statements pointing out the important role of magnetic helicity in solar flares and coronal mass ejections(CMEs).Here we construct a sample of 47 solar flares,which contains 18 no-CME-associated confined flares and 29 CME-associated eruptive flares.We calculate the change ratios of magnetic helicity and magnetic free energy before and after these 47 flares.Our calculations show that the change ratios of magnetic helicity and magnetic free energy show distinct different distributions in confined flares and eruptive flares.The median value of the change ratios of magnetic helicity in confined flares is-0.8%,while this number is-14.5%for eruptive flares.For the magnetic free energy,the median value of the change ratios is-4.3%for confined flares,whereas this number is-14.6%for eruptive flares.This statistical result,using observational data,is well consistent with the theoretical understandings that magnetic helicity is approximately conserved in the magnetic reconnection,as shown by confined flares,and the CMEs take away magnetic helicity from the corona,as shown by eruptive flares.

2015年江苏省结直肠癌发病与死亡分析

目的:分析2015年江苏省肿瘤登记地区结直肠癌发病和死亡情况。方法:依据中国肿瘤登记中心制定的质控方法和评价标准,江苏省疾病预防控制中心对江苏省42个肿瘤登记处上报的2015年全年肿瘤登记资料进行审核和评价,将35个符合质控标准的肿瘤登记处资料汇总成库。按城乡、性别及年龄组分层,计算结直肠癌发病(死亡)率、年龄别发病(死亡)率、累积发病(死亡)率(0~74岁)和截缩发病(死亡)率(35~ 64岁);采用2000年中国普查标准人口构成和Segi's世界标准人口构成计算中国人口标化率(中标率)和世界人口标化率(世标率)。结果:2015年江苏省35个肿瘤登记地区覆盖人口38761144人(城市15168594人,农村23592550人),新发结直肠癌病例11051例,发病率为28.51/10万,中标率为15.43/10万,世标率为15.20/10万,累积发病率(0~ 74岁)为1.81%,截缩发病率(35~64岁)为23.71/10万;城市地区发病率为33.87/10万,中标率为18.44/10万;农村地区发病率为25.06/10万,中标率为13.54/10万。2015年因结直肠癌死亡5436例,死亡率为14.02/10万,中标率为6.92/10万,世标率为6.81/10万,累积死亡率(0~ 74岁)为0.70%和截缩死亡率(35~ 64岁)为8.08/10万;城市地区死亡率为16.57/10万,中标率为8.27/10万;农村地区死亡率为12.39/10万,中标率为6.07/10万。结论:2015年江苏省结直肠癌发病和死亡水平均呈上升趋势,城市与农村之间存在差异,疾病负担呈逐年加重趋势,应加强结直肠癌的预防和控制工作。

水热法制备的ZnO纳米线的微结构、光学性质以及光学模型

在90°C的温度环境下,采用水热化学沉积法制备ZnO纳米线薄膜,然后用扫描电子显微镜、透射光谱和X射线衍射等技术对所制备的纳米薄膜进行表征。结果表明,制备的纳米ZnO薄膜的光学带隙在3.274到3.347 eV之间。调节pH值可以控制膜的孔隙率和显微结构。SEM照片清楚地显示两层结构,且这两层的空隙率不同。XRD结果显示(002)取向的优先生长。针对纳米结构的ZnO薄膜建立一个完整的光学模型,包括Bruggeman有效介质近似、粗糙表面的光散射和O’Leary-Johnson-Lim带间吸收模型。利用此光学模型,拟合实验测量的纳米结构ZnO薄膜的透射光谱,拟合结果同实验结果具有很高的一致性。

Enhanced recovery after surgery with laparoscopic radical gastrectomy for stomach carcinomas

AIM: To study the efficacy of the enhanced recovery after surgery(ERAS) program in laparoscopic radical gastrectomy for stomach carcinomas.METHODS: From June 2010 to December 2012, 61 gastric cancer patients who underwent laparoscopicassisted radical gastrectomy with D2 lymphadenectomy at First Hospital of Jilin University were enrolled in this randomized controlled trial.(Clinical Trials.gov, registration ID: NCT01955096). The subjects were divided into the ERAS program group and the conventional control group. The clinical characteristics, recovery variables, and complications of patients were analyzed.RESULTS: The time to first ambulation, oral food intake, and time to defecation were significantly shorter in the ERAS group(n = 30), compared to the conventional group(n = 31; P = 0.04, 0.003, and 0.01, respectively). The postoperative hospital stay was less in the ERAS group(6.8 ± 1.1 d) compared to the conventional group(7.7 ± 1.1 d)(P = 0.002). There was no significant difference in postoperative complications between the ERAS(1/30) and conventional care groups(2/31)(P = 1.00). There were no readmissions or mortality during the 30-d follow-up period.CONCLUSION: The ERAS program is associated with a shorter hospital stay in gastric cancer patients undergoing laparoscopic radical gastrectomy. The ERAS protocol is useful in the treatment of gastric cancer.

Randomized controlled trial of uncut Roux-en-Y vs Billroth Ⅱ reconstruction after distal gastrectomy for gastric cancer: Which technique is better for avoiding biliary reflux and gastritis?

AIM To identify which technique is better for avoiding biliary reflux and gastritis between uncut Roux-en-Y and Billroth Ⅱ reconstruction. METHODS A total of 158 patients who underwent laparoscopyassisted distal gastrectomy for gastric cancer at the First Hospital of Jilin University(Changchun, China) between February 2015 and February 2016 were randomized into two groups: uncut Roux-en-Y(group U) and Billroth II group(group B). Postoperative complications and relevant clinical data were compared between the two groups. RESULTS According to the randomization table, each group included 79 patients. There was no significant difference in postoperative complications between groups U and B(7.6% vs 10.1%, P = 0.576). During the postoperative period, group U stomach p H values were lower than 7 and group B p H values were higher than 7. After 1 year of follow-up, group B presented a higher incidence of biliary reflux and alkaline gastritis. However, histopathology did not show a significant difference in gastritis diagnosis(P = 0.278), and the amount of residual food and gain of weight between the groups were also not significantly different. At 3 mo there was no evidence of partial recanalization of uncut staple line, but at 1 year the incidence was 13%. CONCLUSION Compared with Billroth II reconstruction, uncut Rouxen-Y reconstruction is secure and feasible, and can effectively reduce the incidence of alkaline reflux, residual gastritis, and heartburn. Despite the incidence of recanalization, uncut Roux-en-Y should be widely applied.

Laparoscopic total mesorectal excision with natural orifice specimen extraction

AIM:To introduce transvaginal or transanal specimen extraction in laparoscopic total mesorectal excision surgery to avoid an abdominal incision. METHODS:Between January 2009 and December 2011,21 patients with rectal cancer underwent laparoscopic radical resection and the specimen was retrieved by two different ways:transvaginal or transanal rectal removal.Transvaginal specimen extraction approach was strictly limited to elderly post-menopausal women who need hysterectomy.Patients aged between 30 and 80 years,with a body mass index of less than 30 kg/m2, underwent elective surgery.The surgical technique and the outcomes related to the specimen extraction,such as duration of surgery,length of hospital stay,and the complications were retrospectively reviewed. RESULTS:Laparoscopic resection using a natural orifice removal approach was successful in all of the 21 patients.Median operating time was 185 min(range,122-260 min)and the estimated blood loss was 48 mL. The mean length of hospital stay was 7.5 d(range,2-11 d).One patient developed postoperative ileus and had an extended hospital stay.The patient complained of minimal pain.There were no postoperative complications or surgery-associated death.The mean size of the lesion was 2.8 cm(range,1.8-6.0 cm),and the mean number of lymph nodes harvested was 18.7(range, 8-27).At a mean follow-up of 20.6 mo(range,10-37 mo),there were no functional disorders associated with the transvaginal and transanal specimen extraction. CONCLUSION:Transvaginal or transanal extraction in L-TME is a safe and effective procedure.Natural orifice specimen extraction can avoid the abdominal wall incision and its potential complications.

Boron modulating electronic structure of FeN4C to initiate high-efficiency oxygen reduction reaction and high-performance zinc-air battery

The biggest challenge is to develop a low cost and readily available catalyst to replace expensive commercial Pt/C for efficient electrochemical oxygen reduction reaction(ORR).In this research,closo-[B_(12)H_(12)]^(2−)and 1,10-phenanthroline-iron complexes were introduced into the porous metal-organic framework by impregnation method,and further annealing treatment achieved the successful anchoring of single-atom-Fe in B-doped CN Matrix(FeN4CB).The ORR activity of FeN4CB is comparable to the widely used commercial 20 wt%Pt/C.Where the half-wave potential(E_(1/2))in alkaline medium up to 0.84 V,and even in the face of challenging ORR in acidic medium,the E_(1/2)of ORR driven by FeN4CB is still as high as 0.81 V.When FeN4CB was used as air cathode,the open circuit voltage of Zn-air battery reaches 1.435 V,and the power density and specific capacity are as high as 177 mW cm^(−2)and 800 mAh g_(Zn)^(−1)(theoretical value:820 mAh g_(Zn)^(−1)),respectively.The dazzling point of FeN4CB also appears in the high ORR stability,whether in alkaline or acidic media,E_(1/2)and limiting current density are still close to the initial value after 5000 times cycles.After continuously running the charge-discharge test for 220 h,the charge voltage and discharge voltage of the rechargeable zinc-air battery with FeN4CB as the air cathode maintained the initial state.Density functional theory calculations reveals that introducing B atom to Fe–N4–C can adjust the electronic structure to easily break O=O bond and significantly reduce the energy barrier of the rate-determining step resulting in an improved ORR activity.

An efficient method for vibration and stability analysis of rectangular plates axially moving in fluid

An efficient method is developed to investigate the vibration and stability of moving plates immersed in fluid by applying the Kirchhoff plate theory and finite element method.The fluid is considered as an ideal fluid and is described with Bernoulli’s equation and the linear potential flow theory.Hamilton’s principle is used to acquire the dynamic equations of the immersed moving plate.The mass matrix,stiffness matrix,and gyroscopic inertia matrix are determined by the exact analytical integration.The numerical results show that the fundamental natural frequency of the submersed moving plates gradually decreases to zero with an increase in the axial speed,and consequently,the coupling phenomenon occurs between the first-and second-order modes.It is also found that the natural frequency of the submersed moving plates reduces with an increase in the fluid density or the immersion level.Moreover,the natural frequency will drop obviously if the plate is located near the rigid wall.In addition,the developed method has been verified in comparison with available results for special cases.

Retrieval of leaf biochemical properties by inversed PROSPECT model and hyperspectral indices:an application to Populus euphratica polymorphic leaves

Leaf biochemical properties have been widely assessed using hyperspectral reflectance information by inversion of PROSPECT model or by using hyperspectral indices, but few studies have focused on arid ecosystems. As a dominant species of riparian ecosystems in arid lands, Populus euphratica Oliv. is an unusual tree species with polymorphic leaves along the vertical profile of canopy corresponding to different growth stages. In this study, we evaluated both the inversed PROSPECT model and hyperspectral indices for estimating biochemical properties of P. euphratica leaves. Both the shapes and biochemical properties of P. euphratica leaves were found to change with the heights from ground surface. The results indicated that the model inversion calibrated for each leaf shape performed much better than the model calibrated for all leaf shapes, and also better than hyperspectral indices. Similar results were obtained for estimations of equivalent water thickness （EWT） and leaf mass per area （LMA）. Hyperspectral indices identified in this study for estimating these leaf properties had root mean square error （RMSE） and R2 values between those obtained with the two calibration strategies using the inversed PROSPECT model. Hence, the inversed PROSPECT model can be applied to estimate leaf biochemical properties in arid ecosystems, but the calibration to the model requires special attention.

Explosion temperature mapping of emulsion explosives containing TiH_(2)powders with the two-color pyrometer technique

In the study,the two-color pyrometer technique was used to measure the transient temperature field of emulsion explosives with different contents of TiH_(2)powders.The experimental results showed that the introduction of TiH_(2)powders could significantly increase the explosion temperature and fireball duration of emulsion explosive.When emulsion explosives were ignited,the average explosion temperature of pure emulsion explosive continuously decreased while emulsion explosives added with TiH_(2)powders increased at first and then decreased.When the content of TiH_(2)powders was 6 mass%,the explosion average temperature reached its maximum value of 3095 K,increasing by 43.7%as compared with that of pure emulsion explosive.In addition,the results of air blast experiment and explosion heat test showed that the variation trends of shock wave parameters,explosion heat and theoretical explosion temperature of emulsion explosives with different contents of TiH_(2)powders were basically consistent with that of explosion temperature measured by the two-color pyrometer technique.In conclusion,the two-color pyrometer technique would be conducive to the formula design of emulsion explosive by understanding the explosion temperature characteristics.

绕丹宁衍生物的合成方法和生物活性研究

通过优化绕丹宁及其衍生物的合成路线,合成一系列绕丹宁衍生物,并研究其生物活性.以双羧甲基三硫代碳酸盐为原料,在水做溶剂的条件下与相应的胺反应,生成绕丹宁环,然后再与不同取代基的醛脱水缩合得到目标化合物.其结构经核磁共振谱等表征且同时进行抑菌活性测定.目标化合物5a,5c,5d对革兰氏阳性菌具有较好的抑菌活性,目标化合物5a,5b,5c,5d,5l,5n对革兰氏阴性菌具有较好的抑菌活性.该合成方法可用于合成绕丹宁类CFTR抑制剂.

Ubiquitin-like modifier activating enzyme 2 promotes cell migration and invasion through Wnt/β-catenin signaling in gastric cancer

AIM To investigate the function and mechanism of ubiquitinlike modifier activating enzyme 2(Uba2) in progression of gastric cancer(GC) cells.METHODS Uba2 level in patients with GC was analyzed by Western blotting and immunohistochemistry. MTT and colony formation assays were performed to examine cell proliferation.Flow cytometry was used for cell cycle analysis.Wound healing and Transwell assays were conducted to examine the effects of Uba2 on migration and invasion.Expression levels of cell cycle-related proteins, epithelial-mesenchymal transition(EMT) biomarkers, and involvement of the Wnt/β-catenin pathway was assessed by Western blotting. Activation of the Wnt/β-catenin pathway was confirmed by luciferase assay.RESULTS Uba2 expression was higher in GC than in normal tissues.Increased Uba2 expression was correlated with tissue differentiation, Lauren's classification, vascular invasion,and TNM stage, as determined by the analysis of 100 GC cases(P < 0.05). Knock-down of Uba2 inhibited GC cell proliferation, induced cell cycle arrest, and altered expression of cyclin D1, P21, P27, and Bcl-2, while upregulation of Uba2 showed the opposite effects. The wound healing and Transwell assays showed that Uba2 promoted GC cell migration and invasion. Western blotting revealed alterations in EMT biomarkers, suggesting the role of Uba2 in EMT. Furthermore, the luciferase reporter assay indicated the involvement of the Wnt/β-catenin signaling pathway as a possible modulator of Uba2 oncogenic functions.CONCLUSION Uba2 plays a vital role in GC cell migration and invasion,possibly by regulating the Wnt/β-catenin signaling pathway and EMT.

Electrochemical oxygen evolution reaction efficiently boosted by selective fluoridation of FeNi3 alloy/oxide hybrid

Performance boosting of hybrid metal oxide and metal alloy catalyst is crucial to the water electrolysis for hydrogen generation. Herein, a novel concept of selective fluoridation of metal alloy/oxide hybrid is proposed to boost their catalytic performance for the oxygen evolution reaction(OER). A well-recognized OER catalyst system of FeNi3 alloy/oxide embedded in nitrogen-doped porous nanofibers(FeNiO/NCF) is employed as a proof of concept, and it is selectively fluoridated by transforming the metal oxide to metal fluoride(FeNiF/NCF). The crystal structure and surface chemical state transformation are well supported by the spectroscopic analysis and the improved electrochemical performance for OER can be well correlated to the phase and structure change. Specifically, FeNiF/NCF can drive the benchmark current density of 10 mA cm-2 at 260 mV with a Tafel slope of 67 mV dec-1, about 70 mV less than that of FeNiO/NCF.Increased catalytic kinetics, rapid charge transfer ability, high catalytic efficiency and stability are also probed by electrochemical analysis. The high surface area and roughness are found mainly generated via the high-temperature annealing for the metal alloy/metal oxide formation, and the low-temperature fluoridation process intrinsically contributes to the active structure formation. It is an efficient and universal approach to increase the catalytic performance of metal alloy/oxide for energy-relevant catalytic reactions.

What is the best surgical procedure of transverse colon cancer?An evidence map and minireview

Colorectal cancers comprise a large percentage of tumors worldwide,and transverse colon cancer(TCC)is defined as tumors located between hepatic and splenic flexures.Due to the anatomy and embryology complexity,and lack of large randomized controlled trials,it is a challenge to standardize TCC surgery.In this study,the current situation of transverse/extended colectomy,robotic/laparoscopic/open surgery and complete mesocolic excision(CME)concept in TCC operations is discussed and a heatmap is conducted to show the evidence level and gap.In summary,transverse colectomy challenges the dogma of traditional extended colectomy,with similar oncological and prognostic outcomes.Compared with conventional open resection,laparoscopic and robotic surgery plays a more important role in both transverse colectomy and extended colectomy.The CME concept may contribute to the radical resection of TCC and adequate harvested lymph nodes.According to published studies,laparoscopic or robotic transverse colectomy based on the CME concept was the appropriate surgical procedure for TCC patients.

Great efficacy of sulfachloropyrazine-sodium against acute murine toxoplasmosis

Objective:To identify more effective and less toxic drugs to treat animal toxoplasmosis.Methods:Efficucy of seven kinds of sulfonamides against Toxoplasma gondii(T.gondii)in an acute murine model was evaluated.The mice used throughout the study were randomly assigned to many groups(10 mice each),which either remained uninfected or were infected intraperitoneally with lachyzoites of T.gondii(strains RH and CN).All groups were then treated with different sulfonamides and the optimal treatment protocol was determined candidates.Sulfadiazine-sodium(SD)was used for comparison.Results:The oplimal therapy involved gavaging mice twice per day with 250 mg/kg bw of sulfachloropyrazine-sodium(SPZ)for five days.Using this protocol,the average survival time and the time-point of 50%fatalities were prolonged significantly compared with SD treatment.Treatment with SFZ protected 40%of mice from death,and the heart and kidney tissue of these animals was parasite-free,as determined by nestedPCK.SPZ showed excellent therapeutic effects in the treatment of T.gondii in an acute murine model and is therefore a promising drug candidate for the treatment and prevention of T.gondii in animals.Conclusions:It can be concluded that the effective drug sulfachloropyrazine may be the new therapeutic options against animal toxoplasmosis.

Effects of different plasma expanders on rats subjected to severe acute normovolemic hemodilution

Background:Plasma expanders are widely used for acute normovolemic hemodilution(ANH).However,existing studies have not focused on large-volume infusion with colloidal plasma expanders,and there is a lack of studies that compare the effects of different plasma expanders.Methods:The viscosity,hydrodynamic radius(Rh)and colloid osmotic pressure(COP)of plasma expanders were determined by a cone-plate viscometer,Zetasizer and cut-off membrane,respectively.Sixty male rats were randomized into five groups with Gelofusine(Gel),Hydroxyethyl Starch 200/0.5(HES200),Hydroxyethyl Starch 130/0.4(HES130),Hydroxyethyl Starch 40(HES40),and Dextran 40(Dex40),with 12 rats used in each group to build the ANH model.ANH was performed by the withdrawal of blood and simultaneous infusion of plasma expanders.Acid-base,lactate,blood gas and physiological parameters were detected.Results:Gel had a lower intrinsic viscosity than HES200 and HES130(P<0.01),but at a low shear rate in a mixture of colloids,red cells and plasma,Gel had a higher viscosity(P<0.05 or P<0.01,respectively).For hydroxyethyl starch plasma expanders,the COP at a certain concentration decreases from 11.1 mmHg to 6.1 mmHg with the increase of Rh from 10.7 nm to 20.2 nm.A severe ANH model,with the hematocrit of 40%of the baseline level,was established and accompanied by disturbances in acid-base,lactate and blood gas parameters.At the end of ANH and 60 min afterward,the Dex40 group showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other groups.The systolic blood pressure(SBP),diastolic blood pressure(DBP),and mean arterial pressure(MAP)decreased significantly in all groups at the end of ANH.The DBP and MAP in the Dex40 group further decreased 60 min after the end of ANH.During the process of ANH,the Dex40 group showed a drop and recovery in SBP,DBP and MAP.The DBP and MAP in the HES200 group were significantly higher than those in the other groups at some time points(P<0.05 or P<0.01).Conclusions:Gel had a low intrinsic viscosity but may increase the whole blood viscosity at low shear rates.Rh and COP showed a strong correlation among hydroxyethyl starch plasma expanders.Dex40 showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other plasma expanders.During the process of ANH,Dex40 displayed a V-shaped recovery pattern for blood pressure,and HES200 had the advantage in sustaining the DBP and MAP at some time points.

High-Dimensional Spatial Standardization Algorithm for Diffusion Tensor Image Registration

Three high dimensional spatial standardization algorithms are used for diffusion tensor image(DTI)registration,and seven kinds of methods are used to evaluate their performances.Firstly,the template used in this paper was obtained by spatial transformation of 16 subjects by means of tensor-based standardization.Then,high dimensional standardization algorithms for diffusion tensor images,including fractional anisotropy(FA)based diffeomorphic registration algorithm,FA based elastic registration algorithm and tensor-based registration algorithm,were performed.Finally,7 kinds of evaluation methods,including normalized standard deviation,dyadic coherence,diffusion cross-correlation,overlap of eigenvalue-eigenvector pairs,Euclidean distance of diffusion tensor,and Euclidean distance of the deviatoric tensor and deviatoric of tensors,were used to qualitatively compare and summarize the above standardization algorithms.Experimental results revealed that the high-dimensional tensor-based standardization algorithms perform well and can maintain the consistency of anatomical structures.