缩小教育数字鸿沟实现全面教育数字化转型——美国《2024年国家教育技术计划》解读及启示

当前,数字鸿沟已经成为各国推动教育数字化转型的关键瓶颈问题。2024年初,美国发布《缩小数字访问、设计与使用鸿沟的行动倡议——2024年国家教育技术计划》,聚焦美国社会如何缩小教育数字鸿沟,从教育数字资源获取、数字化教育教学设计以及如何使用数字化技术三个方面,阐述美国未来五年的行动规划和指南。该计划重点提出,为应对教育领域中的三种数字鸿沟,应提前绘制三种画像。一是学习者画像,了解未来学习者在大学、职场和社会生活中成功所需的技能和特质。二是教师画像,了解教师需要具备哪些知识和能力,以帮助学生在课堂上培养这些技能。三是学习环境画像,了解为实现系统地帮助教师和学习者发展,如何设计和建设数字基础设施。基于该计划的解读与分析,提出对我国的三点启示:一是加快发展新质生产力,提高全民数字素养和技能;二是全面构建“师—生—环境—区域”融合图谱,提高教育数据治理水平;三是创新人机协同模式,赋能高阶思维发展。

Against all odds:The road to success in the development of human immune reconstitution mice

The mouse genome has a high degree of homology with the human genome,and its physiological,biochemical,and developmental regulation mechanisms are similar to those of humans;therefore,mice are widely used as experimental animals.However,it is undeniable that interspecies differences between humans and mice can lead to experimental errors.The differences in the immune system have become an impor-tant factor limiting current immunological research.The application of immunodefi-cient mice provides a possible solution to these problems.By transplanting human immune cells or tissues,such as peripheral blood mononuclear cells or hematopoietic stem cells,into immunodeficient mice,a human immune system can be reconstituted in the mouse body,and the engrafted immune cells can elicit human-specific immune responses.Researchers have been actively exploring the development and differen-tiation conditions of host recipient animals and grafts in order to achieve better im-mune reconstitution.Through genetic engineering methods,immunodeficient mice can be further modified to provide a favorable developmental and differentiation microenvironment for the grafts.From initially only being able to reconstruct single T lymphocyte lineages,it is now possible to reconstruct lymphoid and myeloid cells,providing important research tools for immunology-related studies.In this review,we compare the differences in immune systems of humans and mice,describe the devel-opment history of human immune reconstitution from the perspectives of immuno-deficient mice and grafts,and discuss the latest advances in enhancing the efficiency of human immune cell reconstitution,aiming to provide important references for im-munological related researches.

Effect of processing on the alkaloids in Aconitum tubers by HPLC-TOF/MS

According to the Chinese Pharmacopoeia 2015, only processed Aconitum tubers can be clinically applied, and the effect of processing is unclear. This research aimed to explore the effect of processing on cardiac efficacy of alkaloids in Aconitum tubers. First, the chemical ingredients in unprocessed and processed Aconitum tubers were identified and compared by using high performance liquid chromatography time-of-flight mass spectrometry(HPLC-TOF/MS) and multivariate pattern recognition methods. Then the representative alkaloids in Aconitum tubers, aconitine, benzoylaconine, and aconine, which belong to diester-diterpenoid alkaloids,monoester-diterpenoid alkaloids, and amine-diterpenoid alkaloids, respectively, were selected for further validation of attenuated mechanism. Subsequent pharmacological experiments with aconitine, benzoylaconine,and aconine in SD rats were used to validate the effect of processing on cardiac functions. After processing the Aconitum tubers, it was found that the contents of diester-diterpenoid alkaloids were reduced, and those of monoester-diterpenoid alkaloids and amine-diterpenoid alkaloids were increased, suggesting that diesterditerpenoid alkaloids were transformed into monoester-diterpenoid alkaloids and amine-diterpenoid alkaloids.Through further decocting the aconitine in boiling water, it was confirmed that the three alkaloids could be progressively transformed. Pharmacological experiments with aconitine, benzoylaconine, and aconine in SD rats showed that aconitine at a dose of 0.01 mg/kg and aconine at a dose of 10 mg/kg enhanced the cardiac function, while benzoylaconine at a dose of 2 mg/kg weakened the cardiac function. The effect of processing is attributed to the transformation of the most toxic diester-diterpenoid alkaloids into less toxic monoesterditerpenoid alkaloids and amine-diterpenoid alkaloids.

Identification of differentially expressed genes related to radioresistance of human esophageal cancer cells

Background and Objective: Radioresistant cells in esophageal cancer is one of the important reasons for the local failure of radiotherapy. In recent years, some researchers used gene chip technology to screen the differentially expressed genes between parental and radioresistant human esophageal cancer cells. But there were some problems in these studies, for example comparing cells at only one time interval, and genetic background not matching. In this study, we selected 3 different pairs of parental and radioresistant human esophageal cancer cells, and compared the gene expression profiles by cDNA microarray at 3 time intervals to identify and analyze the differentially expressed genes between parental and radioresistant human esophageal cancer cells. Methods: We compared the gene expression profiles between parental cells (TE13, Seg-1, Kyse170) and radioresistant cells (TE13R, Seg-1R, Kyse170R) before, and at 8 h and 24 h after irradiation with a cDNA microarray consisting of 48 000 genes (Human Genome). We identified differentially expressed genes by Pathway and GO analyses, and verified the differentially expressed genes LEF1 and CTNNB1 by RT-PCR. Results: A total of 460, 451, and 397 differentially expressed genes were found before, and at 8 h and 24 h after irradiation. After Pathway and GO analyses, 14 differentially expressed genes, participating in cell growth, apoptosis, cell cycle regulation, gene repair and signal transmission, were selected to further research. LEF1 and CTNNB1 were verified by RT-PCR, and the results were consistent with those of cDNA microarray. Conclusions: The WNT signal pathway may be an important pathway participating in the formation of radioresistance of esophageal cancer cells. LEF1 and CTNNB1 may be the important genes causing the esophageal cancer cell radioresistance.

Graph Regularized L_p Smooth Non-negative Matrix Factorization for Data Representation

This paper proposes a Graph regularized Lpsmooth non-negative matrix factorization(GSNMF) method by incorporating graph regularization and L_p smoothing constraint, which considers the intrinsic geometric information of a data set and produces smooth and stable solutions. The main contributions are as follows: first, graph regularization is added into NMF to discover the hidden semantics and simultaneously respect the intrinsic geometric structure information of a data set. Second,the Lpsmoothing constraint is incorporated into NMF to combine the merits of isotropic(L_2-norm) and anisotropic(L_1-norm)diffusion smoothing, and produces a smooth and more accurate solution to the optimization problem. Finally, the update rules and proof of convergence of GSNMF are given. Experiments on several data sets show that the proposed method outperforms related state-of-the-art methods.

Comparative analysis of essential oils found in Rhizomes Curcumae and Radix Curcumae by gas chromatography-mass spectrometry

A comparison of the volatile compounds in Rhizomes Curcumae （Ezhu） and Radix Curcumae （Yujin） was undertaken using gas chromatography mass spectrometi-y （GC-MS）. Ultrasonic extraction and GC-MS methods were developed for the simultaneous determination of five sesquiterpenes, namely, α-pinene, β-elemene, curcumol, germacrone and curdione, in Ezhu and Yunjin. Good linearity （r〉0.999） and high inter-day precision were observed over the investigated concentration ranges. The validated method was successfully used for the simultaneous determination of five sesquiterpenes in Ezhu and Yujin. The quantitative method can be effectively used to evaluate and monitor the quality of Chinese curcuma in clinical use.

State of rare earth elements in the rare earth deposits of Northwest Guizhou,China

We studied the states of rare earth elements in ore of the Xianglushan rare earth deposit. Rare earth ore samples were tested and examined by scanning electron microscope, electron probe, and chemical leaching. No independent rare earth minerals were detected by scanning electron microscope. Elements detected by the electronic probe for the in situ micro-zone of the sample included: O,Al, Si, Ca, Mg, Fe, Ti, K, Na, S, Cl, C, Cu, Cr, V, and Pt.Rare earth elements were not detected by electron probe.(NH_4)_2 SO_4,(NH_4)Cl, NaCl, and H_2 SO_4 were used as reagents in chemical leaching experiments that easily leached out rare earth elements under the action of 10%reagent, indicating that the rare earth elements in ore are mainly in the ionic state rather than present as rare earth minerals.

UPLC-Q-TOF/MS based metabolomic profiling of serum and urine of hyperlipidemic rats induced by high fat diet

Hyperlipidemia is considered to be a high lipid level in blood,can induce metabolic disorders and dysfunctions of the body,and results in some severe complications.Therefore,hunting for some metabolite markers and clarifying the metabolic pathways in vivo will be an important strategy in the treatment and prevention of hyperlipidemia.In this study,a rat model of hyperlipidemia was constructed according to histopathological data and biochemical parameters,and the metabolites of serum and urine were analyzed by UPLC-Q-TOF/MS.Combining pattern recognition and statistical analysis.19 candidate biomarkers were screened and identified.These changed metabolites indicated that during the development and progression of hyperlipidemia,energy metabolism,lipid metabolism,amino acid metabolism and nucleotide metabolism were mainly disturbed,which are reported to be closely related to diabetes,cardiovascular diseases,etc.This study demonstrated that a UPLC-Q-TOF/MS based metabolomic approach is useful to profile the alternation of endogenous metabolites of hyperlipidemia.

Differential gene expression profiles of DNA repair genes in esophageal cancer cells after X-ray irradiation

Bckground and Objective: Various factors affect the radioresistance of tumor cells, with unknown molecular mechanism(s). Many genes have been found to associate with the radioresistance of tumor cells, however, the precise mechanism of these genes have not been elucidated. This paper was to analyze the differential expressions of DNA repair genes in esophageal carcinoma cells at different time after X-ray irradiation, and to investigate the role of these DNA repair genes in radiation resistance. Methods: Esophageal cancer parental cells Seg-1 were treated with continuous 2 Gy of fractionated irradiation until the total dose reached 60 Gy to establish the radioresistant cell line Seg-1R. Total RNA was extracted from each cell line at 0, 8, and 24 h after irradiation. Illumine Human-6 V3 microarray was used to identify differentially expressed genes between parental and radioresistant cells. Ten genes involved in DNA repair were obtained and their expressions at different time points after irradiation were analyzed by Gene Ontology analysis. Results: Ten DNA repair associated genes were found to be differentially expressed. Three of these genes, SLK, HMGB1, and PMS1, were not only differentially expressed between parental and radioresistant cell lines, but also expressed differently at different time points after irradiation in the same cell line. Conclusions: PMS1 may be an important factor involved in the mechanism of radioresistance of esophageal carcinoma cells.

Total Variation Constrained Non-Negative Matrix Factorization for Medical Image Registration

This paper presents a novel medical image registration algorithm named total variation constrained graphregularization for non-negative matrix factorization(TV-GNMF).The method utilizes non-negative matrix factorization by total variation constraint and graph regularization.The main contributions of our work are the following.First,total variation is incorporated into NMF to control the diffusion speed.The purpose is to denoise in smooth regions and preserve features or details of the data in edge regions by using a diffusion coefficient based on gradient information.Second,we add graph regularization into NMF to reveal intrinsic geometry and structure information of features to enhance the discrimination power.Third,the multiplicative update rules and proof of convergence of the TV-GNMF algorithm are given.Experiments conducted on datasets show that the proposed TV-GNMF method outperforms other state-of-the-art algorithms.

Estimation of the kinetic parameters for thermal decomposition of HNIW and its adiabatic time-to-explosion by Kooij formula

A differential/integral method to estimate the kinetic parameters(apparent activation energy Eaand pre-exponential factor A) for thermal decomposition reaction of energetic materials based on Kooij formula are applied to study the nonisothermal decomposition reaction kinetics of hexanitrohexaazaisowurtzitane(HNIW) by analyzing nonisothermal DSC curve data. The apparent activation energy(Ea) obtained by the integral isoconversional non-isothermal method based on Kooij formula is used to check the constancy and validity of apparent activation energy by the differential/integral method based on Kooij formula. The most probable mechanism function of thermal decomposition reaction of HNIW is determined by a logical choice method. The equations for calculating the critical temperatures of thermal explosion(Tb) and adiabatic time-toexplosion(tTIad) based on Kooij formula are used to calculate the values of Tband tTIadto evaluate the thermal safety and heat-resistant ability of HNIW. All the original data needed for analyzing the kinetic parameters are from nonisothermal DSC curves. The results show that the kinetic model function in differential form and the values of Eaand A of decomposition reaction of HNIW are 3(1 a)[ ln(1 a)]2/3, 152.73 kJ mol 1and 1011.97s 1, respectively, and the values of self-accelerating decomposition temperature(TSADT), Tband tTIadare 486.55 K, 493.11 K and52.01 s, respectively.

Classification performance of model coal mill classifiers with swirling and non-swirling inlets

The classification performance of model coal mill classifiers with different bottom incoming flow inlets was experimentally and numerically studied.The flow field adjacent to two neighboring impeller blades was measured using the particle image velocimetry technique.The results showed that the flow field adjacent to two neighboring blades with the swirling inlet was significantly different from that with the non-swirling inlet.With the swirling inlet,there was a vortex located between two neighboring blades,while with the nonswirling inlet,the vortex was attached to the blade tip.The vorticity of the vortex with the non-swirling inlet was much lower than that with the swirling inlet.The classifier with the non-swirling inlet demonstrated a larger cut size than that with the swirling inlet when the impeller was stationary(~0 r·min-1).As the impeller rotational speed increased,the cut size of the cases with non-swirling and swirling inlets both decreased,and the one with the non-swirling inlet decreased more dramatically.The values of the cut size of the two classifiers were close to each other at a high impeller rotational speed(≥120 r·min-1).The overall separation efficiency of the classifier with the non-swirling inlet was lower than that with the swirling inlet,and monotonically increased as the impeller rotational speed increased.With the swirling inlet,the overall separation efficiency first increased with the impeller rotational speed and then decreased when the rotational speed was above 120 r·min-1,and the variation trend of the separation efficiency was more moderate.As the initial particle concentration increased,the cut sizes of both swirling and non-swirling inlet cases decreased first and then barely changed.At a low initial particle concentration(b 0.04 kg·m-3),the classifier with the swirling inlet had a larger cut size than that with the non-swirling inlet.

Glycoalkaloids and phenolic compounds in three commercial potato cultivars grown in Hebei,China

In order to investigate the food nutrition and safety of potato,the objective of the present study is to quantify glycoalkaloids(-chaconine and-solanine)and phenolic compounds in three potato cultivars,namely,Russet Burbank,Atlantic,and Shepody,grown in Hebei,China,and these two classes of biologically active compounds in commercial dehydrated potato flakes were also investigated.The total glycoalkaloid levels in whole potatoes ranged from 4.72 mg/kg for Shepody potatoes to 34.45 mg/kg for Russet Burbank potatoes.The ratio of-chaconine to-solanine in whole potatoes ranged from 0.41 for Russet Burbank potatoes to 3.61 for Atlantic potatoes.The removal rate of total glycoalkaloids in Russet Burbank potatoes during dehydrated potato flake processing is 90.0%.Chlorogenic acid is the dominant phenolic compound in Russet Burbank potatoes.By contrast,Atlantic and Shepody potatoes contain considerable caffeic acid.The loss rate of phenolic compounds in Russet Burbank during dehydrated potato flake processing is 50.47%.

Long-term survival after enucleation of a giant esophagea gastrointestinal stromal tumor

Gastrointestinal stromal tumors(GISTs) are rare mesenchymal neoplasms of the gastrointestinal tract. Less than 1% occurs in the esophagus. Surgery is the primary treatment for patients with GISTs. We report a29-year-old male was admitted after the detection of a posterior mediastinal mass during work-up with routine examination. He did not have any disease-related symptoms. The physical examination was unremarkable. Chest computed tomographic scan, the barium esophagogram and endoscopic esophageal ultrasound showed benign neoplasm. The patient was performed an enucleation surgery through the right posterolateral thoracotomy. The pathology revealed a 13.0 cm × 12.0cm × 5.0 cm mass. The tumor was CD117(C-kit), PDGFRA and DOG1 positive. These findings were consistent with a GIST of the esophagus. So the diagnosis of GIST of esophagus was confirmed. The pathological diagnosis of low grade of GIST of esophagus was confirmed. The patient has no evidence of recurrence and is in good clinical conditions up-to date, five years after surgery.

Prediction of Mechanical Properties of Structural Bamboo and Its Relationship with Growth Parameters

Bamboo is a renewable natural building material with good mechanical properties.However,due to the heterogeneity and anisotropy of bamboo stalk,a large amount of material performance testing costs are required in engineering applications.In this work,longitudinal compression,bending,longitudinal shear,longitudinal tensile,transverse compression and transverse tensile tests of bamboo materials are conducted,considering the influence of the bamboo nodes.The mechanical properties of the whole bamboo stalk with the wall thickness and outer circumference are explored.Through univariate and multiple regression analysis,the relationship between mechanical properties and wall thickness and perimeter is fitted,and the conversion parameters between different mechanical properties are derived.The research results show that the transverse compressive strength of nodal specimen,and transverse tensile strength of nodal and inter-node specimens increase with the increase of wall thickness and outer circumference,but other mechanical properties decrease with the increase of wall thickness and outer circumference.The prediction formula and conversion parameters of bamboo mechanical properties proposed in this research have high applicability and accuracy.Moreover,this research can provide references for the evaluation of bamboo performance and saving test costs.

Preparation and properties of cast polyurethane elastomers with molecularly uniform hard segments based on 2,4-toluene diisocyanate and 3,5-dimethyl-thioltoluenediamine

A series of three cast polyurethane elastomers were prepared from 2,4-toluene diisocyanate (TDI) and 3,5-dimethyl-thioltoluenediamine (D MTDA) chain extender, with polyethylene adi-pate (PEA), polyoxytetramethylene glycol (PTMG) and polycaprolactone (PCL) soft seg-ments. The polyol molecular weights em-ployed was 2000g/mol. The polyurethane elastomers were characterized by an elec-tronmechanical universal testing machine, an Akron abrasion loss tester, a LX-A Shore du-rometer, a rebound resilience equipment and a Dynamic- Mechanical analyzer. In addition, fractured surface of the polyurethane elas-tomers was investigated by a field emission scanning electron microscopy (SEM). The test results showed the PCL based elastomer ex-hibits the excellent tear and stress-strain properties that polyester based elastomers offer, while retaining superior compression set and resilience similar to polyether based elas-tomers. The static and dynamic properties of the PCL based elastomer were more suitable for dynamic applications. The SEM micro-graphs of all polyurethane samples indicated the existing of the microphase separation structure. Particles of the dispersed phase formed by the hard phase and crystalline part of the soft phase grows bigger with the in-creasing crystallinity of the soft segments. The hard domains are irregular shapes and with the sizes of a few micrometers.

Laser capture microdissection enables cellular and molecular studies of tooth root development

Epithelial-mesenchymal interactions（EMIs） are critical for tooth development.Molecular mechanisms mediating these interactions in root formation is not well understood.Laser capture microdissection（LCM） and subsequent microarray analyses enable large scale in situ molecular and cellular studies of root formation but to date have been hindered by technical challenges of gaining intact histological sections of non-decalcified mineralized teeth or jaws with well-preserved RNA.Here,we describe a new method to overcome this obstacle that permits LCM of dental epithelia,adjacent mesenchyme,odontoblasts and cementoblasts from mouse incisors and molars during root development.Using this method,we obtained RNA samples of high quality and successfully performed microarray analyses.Robust differences in gene expression,as well as genes not previously associated with root formation,were identified.Comparison of gene expression data from microarray with real-time reverse transcriptase polymerase chain reaction（RT-PCR） supported our findings.These genes include known markers of dental epithelia,mesenchyme,cementoblasts and odontoblasts,as well as novel genes such as those in the fibulin family.In conclusion,our new approach in tissue preparation enables LCM collection of intact cells with well-preserved RNA allowing subsequent gene expression analyses using microarray and RT-PCR to define key regulators of tooth root development.

Cross-domain identity authentication scheme based on blockchain and PKI system

In vehicular ad hoc networks(VANET),the cross-domain identity authentication of users is very important for the development of VANET due to the large cross-domain mobility of vehicle users.The Public Key Infrastructure(PKI)system is often used to solve the identity authentication and security trust problems faced by VANET.However,the PKI system has challenges such as too centralized Authority of Certification Authority(CA),frequent cross-domain access to certificate interactions and high authentication volume,leading to high certificate management costs,complex cross-domain authentication paths,easy privacy leakage,and overburdened networks.To address these problems,this paper proposes a lightweight blockchain-based PKI identity management and authentication architecture that uses smart contracts to reduce the heavy burden caused by CAs directly managing the life cycle of digital certificates.On this basis,a trust chain based on smart contracts is designed to replace the traditional CA trust chain to meet the general cross-domain requirements,to effectively avoid the communication pressure caused by a mass of certificate transmissions.For the cross-domain scenario with higher privacy and security requirements the identity attribute authentication service is provided directly while protecting privacy by using the Merkle tree to anchor identity attribute data on and off the blockchain chain.Finally,the proposed scheme was comprehensively analyzed in terms of cost,time consumption and security.

Stochastic modeling of subgrid-scale effects on particle motion in forced isotropic turbulence

The subgrid-scale effects on particle motion were investigated in forced isotropic turbulence by DNS and priorLES methods.In the DNS field,the importance of Kolmogorov scaling to preferential accumulation was validated by comparing the radial distribution functions under various particle Stokes numbers.The prior-LES fields were generated by filtering the DNS data.The subgrid-scale Stokes number(StSGS)is a useful tool for determining the effects of subgrid-scale eddies on particle motion.The subgrid-scale eddies tend to accumulate particles with StSGSb 1 and disperse particles with 1 b StSGSb 10.For particles with StSGS?1,the effects of subgrid-scale eddies on particle motion can be neglected.In order to restore the subgrid-scale effects,the Langevin-type stochastic model with optimized parameters was adopted in this study.This model is effective for the particles with StSGS N 1 while has an adverse impact on the particles with StSGSb 1.The results show that the Langevin-type stochastic model tends to smooth the particle distribution in the isotropic turbulence.

规模化猪场猪圆环病毒2型感染的实验室诊断

为了确诊贵州省某规模化猪场保育仔猪异常死亡原因,从怀孕母猪、产房母猪、后备母猪、种公猪、哺乳仔猪、保育仔猪6个猪群采集90份血清样本采用ELISA方法分别进行血清抗体检测,并对采集的90份血清样本和1份病死猪淋巴结组织采用荧光PCR方法进行病原学检测。结果:6个猪群综合的猪瘟病毒、猪蓝耳病病毒、伪狂犬病病毒g B蛋白、伪狂犬病病毒g E蛋白血清抗体阳性率分别为87.78%、70.00%、88.89%、4.44%;猪瘟病毒、猪蓝耳病病毒、伪狂犬病病毒病原核酸检测显示阴性,猪圆环病毒2型病原核酸检测淋巴结组织样本显示阳性。试验结果表明,引起该猪场保育仔猪死亡的原因为猪圆环病毒2型感染。同时,怀孕母猪群出现了伪狂犬病病毒g E蛋白抗体阳性,提示怀孕母猪群可能存在猪伪狂犬病野毒感染。