中国科学技术大学学报最新文献

{"title":"Thermophysical properties of 1D materials: Transient characterization down to atomic level","authors":"Amin Karamati, Shen Xu, Huan Lin, Mahya Rahbar, Xinwei Wang","doi":"10.52396/justc-2023-0098","DOIUrl":"https://doi.org/10.52396/justc-2023-0098","url":null,"abstract":"The thermophysical properties of 1D micro/nanoscale materials could differ significantly from those of their bulk counterparts due to intensive energy carrier scattering by structures. This work provides an in-depth review of cutting-edge techniques employed for transient characterization of thermophysical properties at the micro/nanoscale scale. In terms of transient excitation, step Joule heating, step laser heating, pulsed laser heating, and frequency domain amplitude-modulated laser heating are covered. For thermal probing, electrical and Raman scattering-based physical principles are used. These techniques enable the measurement of thermal conductivity, thermal diffusivity, and specific heat from the sub-mm level down to the atomic level (single-atom thickness). This review emphasizes the advantages of these techniques over steady state techniques and their physics, challenges, and potential applications, highlighting their significance in unraveling the intricate thermal transport phenomena to the atomic level of 1D materials.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135212630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modulating miRNA binding sites within circRNA for enhanced translation efficiency","authors":"Kewei Zhang, Ge Shan, Liang Chen","doi":"10.52396/justc-2023-0048","DOIUrl":"https://doi.org/10.52396/justc-2023-0048","url":null,"abstract":"Circular RNAs (circRNAs) are covalently closed circular RNAs, and some of them preserve translation potency. However, modulation of circRNA translation efficiency and its applications need to be explored. In this study, RNAs containing the translation initiation element CVB3 IRES and the coding sequence of luciferase protein were transcribed and circularized in vitro by T7 RNA polymerase and an optimized permutated intron‒exon (PIE) splicing strategy. The circularized RNAs were then transfected and translated into active luciferase in the cultured cells. Insertion of miRNA binding sites at the flanking region of the luciferase coding sequence significantly reduced the translation efficiency of the circRNAs. Mutations of the miRNA binding sites in the firefly luciferase coding sequence led to increased translation efficiency of synthetic circRNAs in cells. We also proved that mutations of the binding sites of specific miRNAs also enhanced the translation efficiency of synthetic circRNAs. Further in vivo experiments via bioluminescence imaging showed that synonymous mutation of the miRNA binding sites promoted synthetic circRNA translation in nude mice. This study demonstrates that the modulation of miRNA binding sites affects the translation efficiency of synthetic circRNAs in vitro and in vivo, which could be used as versatile tools for future applications in clinical imaging.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135801168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An abnormal multidrug-resistant and hypervirulent &lt;i&gt;Klebsiella pneumoniae&lt;/i&gt; clinical isolate without &lt;i&gt;rmpA&lt;/i&gt; or &lt;i&gt;rmpA2&lt;/i&gt;","authors":"Zhien He, Liwen Cao, Yuanyuan Dai, Huaiwei Lu, Baolin Sun, Yujie Li","doi":"10.52396/justc-2023-0085","DOIUrl":"https://doi.org/10.52396/justc-2023-0085","url":null,"abstract":"<i>Klebsiella pneumoniae</i> is a notorious opportunistic pathogen, especially hypervirulent <i>K</i>. <i>pneumoniae</i> (hvKp). Fortunately, most classical hvKp strains are antibiotic-susceptible. However, in recent years, reports of multidrug-resistant hvKp (MDR-hvKp) have increased dramatically, threatening the health and safety of people worldwide. Here, we report the discovery of MDR-hvKp without <i>rmpA</i> and <i>rmpA2</i> in a 92-year-old patient with chronic obstructive pulmonary disease. The patient died on the eighth day of hospitalization. Phenotyping experiments and whole-genome sequencing of <i>K</i>. <i>pneumoniae</i> isolate 21072329 isolated from the patient’s sputum were performed. Moreover, 21072329 belongs to ST11-KL47 MDR-hvKp, which was highly lethal to <i>Galleria mellonella</i>. Meanwhile, 21072329 had a strong viscosity, and it was difficult to completely centrifuge it; 21072329 carried ESBL genes (<i>bla</i>_CTX-M-65, <i>bla</i>_SHV-158, and <i>bla</i>_TEM-1) and a carbapenemase gene (<i>bla</i>_KPC-2), and it was resistant to carbapenem antibiotics and third- and fourth-generation cephalosporins. Although 21072329 had the characteristics of hvKp, <i>rmpA</i> and <i>rmpA2</i> could not be found in its genome; it also only carried a siderophore of yersiniabactin. This may indicate that other hypervirulence factors promote the formation of hvKp. MDR-hvKp has already brought an enormous burden to global medical care, and those carrying unknown hypervirulence factors are new threats, so urgent prevention and control with research are urgently needed.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"10 47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135801406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicting vapor-liquid equilibria of CO&lt;sub&gt;2&lt;/sub&gt;+HFC binary mixtures by the PR EOS combined with a group contribution model","authors":"Zirui Wu, Lingfeng Shi, Rui Sun, Hua Tian, Xuan Wang, Gequn Shu","doi":"10.52396/justc-2023-0001","DOIUrl":"https://doi.org/10.52396/justc-2023-0001","url":null,"abstract":"CO₂+HFC binary mixtures have good performance and environmental friendliness and are considered good alternative working fluids in cooling and power cycle systems. The vapor-liquid phase equilibrium properties are key to the calculation of the enthalpy and entropy of mixtures, which is critical for the analysis of cooling and power cycle systems. To accurately predict the vapor-liquid equilibrium of CO₂ and HFC (R23, R32, R41, R125, R134a, R143a, R152a, R161, and R227ea) binary mixtures, a group contribution model based on the excess free energy (<i>G</i>^E) mixing rules (PR+MHV1+UNIFAC and PR+LCVM+UNIFAC) is established in this paper. The interaction parameters between groups such as -CO₂, -Alkane, -CHF, and -CHF₃ are obtained by the vapor-liquid phase equilibrium experiment of CO₂ and HFC refrigerants, and these group parameters are critical for predicting their vapor-liquid phase equilibrium properties (the pressures and vapor phase molar fractions). The AARD<i>p</i> value calculated by the PR+LCVM+UNIFAC model is 5.53%, the value of AAD<i>y</i>₁ is 0.0132, and the AARD<i>p</i> and AAD<i>y</i>₁ values of the PR+MHV1+UNIFAC model are 7.40% and 0.0229, respectively. However, for the CO₂+R32 system, the PR+MHV+UNIFAC prediction model can reproduce the experimental data with lower deviations, and the values of AARD<i>p</i> and AAD<i>y</i>₁ are 1.53% and 0.0045, respectively. In summary, for CO₂+HFC binary mixtures, the PR+LCVM+UNIFAC group contribution model can reproduce the experimental data with lower deviations, but for individual CO₂ binary mixtures (such as CO₂+R32), the PR+MHV1+UNIFAC model also has unique advantages. According to the prediction results of the group contribution model, the PR+LCVM+UNIFAC model has significantly improved the calculation progress compared with the PR+MHV1+UNIFAC model used in the previous system.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134981217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of novel double-layer wrapped ammonium polyphosphate and its application in aging-resistant and flame retardant crosslinked polyethylene composites","authors":"Pengfei Jia, Pengfei Sun, Fuhao Yu, Lei Song, Yuan Hu, Bibo Wang","doi":"10.52396/justc-2023-0090","DOIUrl":"https://doi.org/10.52396/justc-2023-0090","url":null,"abstract":"In this study, double-layer wrapped ammonium polyphosphate (APP) is designed to enhance the mechanical properties, resistance and flame retardancy of crosslinked polyethylene (XLPE) composites. APP was wrapped with silica and then grafted with hindered phenol antioxidant 3-(3,5-di-tert-butyl-4 hydroxyphenyl) (AO) to prepare double-layer wrapped flame retardants (MCAPP). Due to the excellent compatibility between the MCAPP and XLPE matrix, the tensile strength and elongation at break of XLPE/MCAPP/CFA (XLPE-4) were improved. Moreover, the retention rate of elongation at break for the XLPE-4 composite reached 61.1%, significantly higher than that of XLPE-1 (2.6%) at 135 °C after aging for 14 d. This demonstrates that MCAPP could improve the aging resistance of XLPE cable composites. Compared with XLPE-1, the maximum smoke density and the peak heat release rate were reduced by 54.9% and 89.7%, respectively. Thus, the double-layer wrapping antioxidant strategy provides an excellent approach to obtain high-performance XLPE composites.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135211338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryopreservation of oocytes: history, achievements and future","authors":"Shiyu Zhao, Gang Zhao","doi":"10.52396/justc-2023-0072","DOIUrl":"https://doi.org/10.52396/justc-2023-0072","url":null,"abstract":"There have been increasing requirements for women’s fertility preservation due to oncological and nononcological reasons in recent years, and meeting these demands will be a hot topic in the coming years. Oocyte cryopreservation is a workable option for preserving women’s fertility, and great advances have already been made and much progress has been made in mammalian gene banking and human oocyte banks. In this paper, we systematically introduce the history of oocyte cryopreservation and vitrification technology and highlight the vitrification carrier. Furthermore, we summarize the fundamentals of oocyte vitrification and discuss the effects of vitrification on oocyte quality. Strategies to improve the effect of oocyte cryopreservation are also proposed. At the end of this review, we conclude oocyte cryopreservation and outline future perspectives.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135800277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of residual stress caused by abrasion on the flexoelectric response of BaTiO&lt;sub&gt;3&lt;/sub&gt; ceramics","authors":"Xu Yang, Dongxia Tian, Xiaoyan Zhang, Ruzhong Zuo, Baojin Chu","doi":"10.52396/justc-2023-0015","DOIUrl":"https://doi.org/10.52396/justc-2023-0015","url":null,"abstract":"The spontaneously polarized surface layer, which originates from stress relaxation, has been proposed for the unexpectedly large flexoelectric response measured in ferroelectric ceramics. However, the source of the stress that led to the polarized surface layer is still not completely known. In this work, the effect of surface stress on the microstructure, dielectric properties and flexoelectric response of BaTiO₃ ceramics abraded by abrasive papers of various grit sizes was systematically studied. Compared with the as-prepared sample, the flexoelectric coefficients of abraded BaTiO₃ ceramics decreased from ~600 μC/m to less than 200 μC/m. The flexoelectric coefficients of all the samples, however, recovered to ~500 μC/m following heat treatment at 200 °C and a subsequent slow cooling process. The results indicate that abrasion can introduce stress on the surface layers and affect the flexoelectric response of ferroelectric ceramics to some extent, but the stress is not the main reason for the formation of polarized surface layers.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135211874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Attention: The impact of media attention on market reaction to corporate violations","authors":"Chenxi Wang, Lei Zhou","doi":"10.52396/justc-2023-0037","DOIUrl":"https://doi.org/10.52396/justc-2023-0037","url":null,"abstract":"Reducing market volatility and achieving high-quality development are important tasks for the Chinese capital market at the present stage. Based on the asset pricing role of media, this study used the event study to empirically examine the impact, as well as the heterogeneity from type and emotional tendency, of media attention on the market reaction to corporate violations from the perspective of limited attention. The results showed that the media’s prior attention to the listed company has a significantly negative impact on the market reaction after the company’s violation. The attention of network media and policy-oriented media has a significantly negative correlation with the market reaction after the company’s violation, while market-oriented media has no significant impact. Compared with neutral media attention, negative and positive media attention trigger more severe negative market reaction after company violations. Furthermore, the negative impact of media attention on the market reaction after corporate violations is mainly manifested in non-state-owned enterprises. The results demonstrate the important role of media attention in asset pricing and have important practical significance for better playing the role of the media, protecting the rights and interests of investors and achieving high-quality development of the capital market.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135710090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sound speed imaging of small animal organs by ultrasound computed tomography","authors":"Zhiming Hu, Mingchun Yang, Xiang Zhu, Chao Tian","doi":"10.52396/justc-2021-0113","DOIUrl":"https://doi.org/10.52396/justc-2021-0113","url":null,"abstract":"Sound speed is an important acoustic parameter for tissue characterization. Herein we developed an ultrasound computed tomography (USCT) system for ex vivo sound speed imaging and evaluation of small animal organs. The proposed USCT system employs a 256-element ring array transducer and allows simultaneous signal transmission and reception for all channels. The method does not require complicated sample preparation procedures and can yield accurate measurement results. Experimental results show that sound speeds of excised rat brain, heart, liver, spleen, and kidney measured by the method are close to published data. This work demonstrates a new method for sound speed imaging and holds potential for in vivo applications.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75560547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation hardness characterization of low gain avalanche detector prototypes for the high granularity timing detector","authors":"Xiao Yang, Kuo-Yan Ma, Xiangxuan Zheng, Yanwen Liu","doi":"10.52396/justc-2021-0204","DOIUrl":"https://doi.org/10.52396/justc-2021-0204","url":null,"abstract":"The high granularity timing detector (HGTD) is a crucial component of the ATLAS phase II upgrade to cope with the extremely high pile-up (the average number of interactions per bunch crossing can be as high as 200). With the precise timing information (σt～30 ps) of the tracks, the track-to-vertex association can be performed in the “4-D” space. The Low Gain Avalanche Detector (LGAD) technology is chosen for the sensors, which can provide the required timing resolution and good signal-to-noise ratio. Hamamatsu Photonics K.K. (HPK) has produced the LGAD with thicknesses of 35 μm and 50 μm. The University of Science and Technology of China(USTC) has also developed and produced 50 μm LGADs prototypes with the Institute of Microelectronics (IME) of Chinese Academy of Sciences. To evaluate the irradiation hardness, the sensors are irradiated with the neutron at the JSI reactor facility and tested at USTC. The irradiation effects on both the gain layer and the bulk are characterized by I-V and C-V measurements at room temperature (20 ℃) or −30 ℃. The breakdown voltages and depletion voltages are extracted and presented as a function of the fluences. The final fitting of the acceptor removal model yielded the c-factor of 3.06×10−16 cm−2, 3.89×10−16 cm−2 and 4.12×10−16 cm−2 for the HPK-1.2, HPK-3.2 and USTC-1.1-W8, respectively, showing that the HPK-1.2 sensors have the most irradiation resistant gain layer. A novel analysis method is used to further exploit the data to get the relationship between the c-factor and initial doping density.","PeriodicalId":17548,"journal":{"name":"Journal of University of Science and Technology of China","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90893584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}