A hierarchical salt-rejection strategy for sustainable and high-efficiency solar-driven desalination

Solar steam generation(SSG)is widely regarded as one of the most sustainable technologies for seawater desalination.However,salt fouling severely compromises the evaporation performance and lifetime of evaporators,limiting their practical applications.Herein,we propose a hierarchical salt-rejection(HSR)strategy to prevent salt precipitation during long-term evaporation while maintaining a rapid evaporation rate,even in high-salinity brine.The salt diffusion process is segmented into three steps—insulation,branching diffusion,and arterial transport—that significantly enhance the salt-resistance properties of the evaporator.Moreover,the HSR strategy overcomes the tradeoff between salt resistance and evaporation rate.Consequently,a high evaporation rate of 2.84 kg m^(-2) h^(-1),stable evaporation for 7 days cyclic tests in 20 wt%NaCl solution,and continuous operation for 170 h in natural seawater under 1 sun illumination were achieved.Compared with control evaporators,the HSR evaporator exhibited a>54%enhancement in total water evaporation mass during 24 h continuous evaporation in 20 wt%salt water.Furthermore,a water collection device equipped with the HSR evaporator realized a high water purification rate(1.1 kg m^(-2) h^(-1)),highlighting its potential for agricultural applications.

面向学生“学”的智能教育软件评估指标体系构建——《2023人工智能促进教育发展报告》节选五

当前智能教育软件市场样态纷繁,软件产品质量参差不齐,教育工作者难以根据教学场景需求选择合适的智能教育软件。通过梳理相关文献与资料,厘清当前智能教育软件评估的研究现状,对现有的教育软件评估指标框架体系进行分析,并根据当前面向学生“学”的智能软件应用场景形态,逐步构建涵盖课堂学习、自主学习、智能作业、社会实践、运动健康五大应用场景的智能教育软件评估指标系,以期帮助使用者在纷繁芜杂、良莠并存的智能教育软件中选到质量高且符合自己使用需求的产品,同时也为监管不同区域的智能教育软件建设和应用情况提供评估标准,规范智能教育软件的监管机制,促进我国人工智能教育应用的有效落地。

Additive manufacturing of Ni-based superalloys: Residual stress, mechanisms of crack formation and strategies for crack inhibition

The additive manufacturing(AM)of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in high-end industrial systems.However,the intense temperature gradient induced by the rapid heating and cooling processes of AM can generate high levels of residual stress and metastable chemical and structural states,inevitably leading to severe metallurgical defects in Ni-based superalloys.Cracks are the greatest threat to these materials’integrity as they can rapidly propagate and thereby cause sudden and non-predictable failure.Consequently,there is a need for a deeper understanding of residual stress and cracking mechanisms in additively manufactured Ni-based superalloys and ways to potentially prevent cracking,as this knowledge will enable the wider application of these unique materials.To this end,this paper comprehensively reviews the residual stress and the various mechanisms of crack formation in Ni-based superalloys during AM.In addition,several common methods for inhibiting crack formation are presented to assist the research community to develop methods for the fabrication of crack-free additively manufactured components.

Heterostructured Mn_(3)O_(4)-MnS Multi-Shelled Hollow Spheres for Enhanced Polysulfide Regulation in Lithium-Sulfur Batteries

Constructing heterojunctions and hollow multi-shelled structures can render materials with fascinating physicochemical properties,and have been regarded as two promising strategies to overcome the severe shuttling and sluggish kinetics of polysulfide in lithium-sulfur(Li-S)batteries.However,a single strategy can only take limited effect.Modulating catalytic hosts with synergistic effects are urgently desired.Herein,Mn_(3)O_(4)-MnS heterogeneous multi-shelled hollow spheres are meticulously designed by controlled sulfuration of Mn2O3 hollow spheres,and then applied as advanced encapsulation hosts for Li-S batteries.Benefiting from the separated spatial confinement by hollow multi-shelled structure,ample exposed active sites and built-in electric field by heterogeneous interface,and synergistic effects between Mn_(3)O_(4)(strong adsorption)and MnS(fast conversion)components,the assembled battery achieves prominent rate capability and decent cyclability(0.016%decay per cycle at 2 C,1000 cycles).More crucially,satisfactory areal capacity reaches up to 7.1 mAh cm^(-2)even with high sulfur loading(8.0 mg cm^(-2))and lean electrolyte(E/S=4.0 pL mg^(-1))conditions.This work will provide inspiration for the rational design of hollow multi-shelled heterostructure for various electrocatalysis applications.

Preparation of graphene on SiC by laser-accelerated pulsed ion beams

Laser-accelerated ion beams(LIBs) have been increasingly applied in the field of material irradiation in recent years due to the unique properties of ultra-short beam duration, extremely high beam current, etc. Here we explore an application of using laser-accelerated ion beams to prepare graphene. The pulsed LIBs produced a great instantaneous beam current and thermal effect on the SiC samples with a shooting frequency of 1 Hz. In the experiment, we controlled the deposition dose by adjusting the number of shootings and the irradiating current by adjusting the distance between the sample and the ion source. During annealing at 1100℃, we found that the 190 shots ion beams allowed more carbon atoms to self-assemble into graphene than the 10 shots case. By comparing with the controlled experiment based on ion beams from a traditional ion accelerator, we found that the laser-accelerated ion beams could cause greater damage in a very short time. Significant thermal effect was induced when the irradiation distance was reduced to less than 1 cm, which could make partial SiC self-annealing to prepare graphene dots directly. The special effects of LIBs indicate their vital role to change the structure of the irradiation sample.

Analysis of the Current Situation of the National Student Physical Fitness Test

The physical health level of adolescents is related to the future of the motherland and the great rejuvenation of the Chinese nation.Through literature review,induction method,and logical analysis,this paper analyzes the policies related to students’physical health,explains the current situation of physical health testing of students in China,summarizes the problems that occur in the process of physical health testing,and finally puts forward suggestions for optimizing physical health testing of college students.

The chemical reprogramming of unipotent adult germ cells towards authentic pluripotency and de novo establishment of imprinting

Although somatic cells can be reprogrammed to pluripotent stem cells(PsCs)with pure chemicals,authentic pluripotency of chemically induced pluripotent stem celis(CipsCs)has never been achieved through tetraploid complementation assay.Spontaneous reprogramming of spermatogonial stem cells(ssCs)was another non-transgenic way to obtain PsCs,but this process lacks mechanistic explanation.Here,we reconstructed the trajectory of mouse SsC reprogramming and developed a five-chemical combination,boosting the reprogramming effciency by nearly 80-to 100-folds.More importantly,chemical induced germline-derived PsCs(5C-gPSCs),but not gpsCs and chemical induced pluripotent stem cells,had authentic pluripotency,as determined by tetraploid complementation.Mechanistically,ssCs traversed through an inverted pathway of in vivo germ ceil development,exhibiting the expression signatures and DNA methylation dynamics from spermatogonia to primordial germ cells and further to epiblasts.Besides,ssC-specific imprinting control regions switched from biallelic methylated states to monoallelic methylated states by imprinting demethylation and then re-methylation on one of the two alleles in 5c-gPsCs,which was apparently distinct with the imprinting reprogramming in vivo as DNA methylation simultaneously occurred on both alleles.Our work sheds ight on the unique regulatory network underpinning SsC reprogramming,providing insights to understand generic mechanisms for cell-fate decision and epigenetic-relateddisorders in regenerative medicine.

Understanding the mechanistic regulation of ferroptosis in cancer:the gene matters

Ferroptosis has emerged as a crucial regulated cell death involved in a variety of physiological processes or pathological diseases,such as tumor suppression.Though initially being found from anticancer drug screening and considered not essential as apoptosis for growth and development,numerous studies have demonstrated that ferroptosis is tightly regulated by key genetic pathways and/or genes,including several tumor suppressors and oncogenes.In this review,we introduce the basic concepts of ferroptosis,characterized by the features of non-apoptotic,iron-dependent,and overwhelmed accumulation of lipid peroxides,and the underlying regulated circuits are considered to be pro-ferroptotic pathways.Then,we discuss several established lipid peroxidation defending systems within cells,including SLC7A11/GPX4,FSP1/CoQ,GCH1/BH4,and mitochondria DHODH/CoQ,all of which serve as anti-ferroptotic pathways to prevent ferroptosis.Moreover,we provide a comprehensive summary of the genetic regulation of ferroptosis via targeting the above-mentioned pro-ferroptotic or anti-ferroptotic pathways.The regulation of proand anti-ferroptotic pathways gives rise to more specific responses to the tumor cells in a contextdependent manner,highlighting the unceasing study and deeper understanding of mechanistic regulation of ferroptosis for the purpose of applying ferroptosis induction in cancer therapy.

USP21 deubiquitylates Nanog to regulate protein stability and stem cell pluripotency

The homeobox transcription factor Nanog has a vital role in maintaining pluripotency and self-renewal of embryonic stem cells(ESCs).Stabilization of Nanog proteins is essential for ESCs.The ubiquitin–proteasome pathway mediated by E3 ubiquitin ligases and deubiquitylases is one of the key ways to regulate protein levels and functions.Although ubiquitylation of Nanog catalyzed by the ligase FBXW8 has been demonstrated,the deubiquitylase that maintains the protein levels of Nanog in ESCs yet to be defined.In this study,we identify the ubiquitin-specific peptidase 21(USP21)as a deubiquitylase for Nanog,but not for Oct4 or Sox2.USP21 interacts with Nanog protein in ESCs in vivo and in vitro.The C-terminal USP domain of USP21 and the C-domain of Nanog are responsible for this interaction.USP21 deubiquitylates the K48-type linkage of the ubiquitin chain of Nanog,stabilizing Nanog.USP21-mediated Nanog stabilization is enhanced in mouse ESCs and this stabilization is required to maintain the pluripotential state of the ESCs.Depletion of USP21 in mouse ESCs leads to Nanog degradation and ESC differentiation.Overall,our results demonstrate that USP21 maintains the stemness of mouse ESCs through deubiquitylating and stabilizing Nanog.

Ion implantation assisted synthesis of graphene on various dielectric substrates

Direct synthesis of high-quality graphene on dielectric substrates is of great importance for the application of graphene-based electronics and optoelectronics. However, high-quality and uniform graphene film growth on dielectric substrates has proven challenging due to limited catalytic ability of dielectric substrates. Here, by employing a Cu ion implantation assisted method, high-quality and uniform graphene can be directly formed on various dielectric substrates including SiO2/Si, quartz glass, and sapphire substrates. The growth rate of graphene on the dielectric substrates was significantly improved due to the catalysis of Cu. Moreover, during the graphene growth process, the Cu atoms gradually evaporated away without involving any metal contamination. Furthermore, an interesting growth behavior of graphene on sapphire substrate was observed, and the results show the graphene domains growth tends to grow along the sapphire flat terraces. The ion implantation assisted approach could open up a new pathway for the direct synthesis of graphene and promote the potential application of graphene in electronics.