A first-principles study on remote van der Waals epitaxy through a graphene monolayer on semiconductor substrates

To investigate the mechanism of remote epitaxy, where the overlayer can follow the same crystalline structure as the underlying semiconductor substrate through a thin two-dimensional interlayer, we systematically study the potential fluctuations of graphene covered Si, Ga As, and Ga N substrates from first-principles. We find that the uneven semiconductor surface, the distorted graphene, and the non-uniform interface charge transfer make significant contributions to the potential fluctuation. The semiconductor substrate with different surface reconstructions and orientations will generate different potential fluctuations through the graphene interlayer. We also calculate and compare the adsorption of adatoms on graphene covered substrates. The adsorption energies of adatoms not only depend on their distances to the underlying semiconductor surface, but are also sensitive to the direction of the charge transfer at the graphene/substrate interface. Changing the semiconductor reconstruction or orientation could even reverse the order of the adsorption energies of cation and anion adatoms by reversing the interface charge transfer direction, leading to a change in the growth orientation of the overlayer.Our study improves the understanding of the mechanism of remote epitaxy, and reveals that it is possible to control the initial nucleation and orientation of overlayers by changing the semiconductor reconstructions and/or orientations in remote epitaxy.

Essential competencies for three grades of midwives in China

Objective:To identify the essential competencies for different grades of midwives in China.Methods:A nationwide modified Delphi process was implemented to amend and screen the indicators.Thirty expert panellists including practitioners (nurse-midwives),clinical managers,academic educators and obstetricians completed a two-round Delphi study through an electronic survey that was supplemented by an expert panel meeting for discussion of comments and suggestions.Results:All panellists completed two rounds of Delphi study and at least 75% of them achieved a consensus on 224 items (W1 =0.150,W2 =0.173).Seven domains were established,namely,'Professional quality','Antenatal care','Intrapartum care','Postnatal care','Neonatal care','Gynaecological care','Public health care & Integrative competency'.Generalised maternal and neonatal knowledge and perinatal care skills were set for'junior'midwives,pathological care for'senior'ones and supervisory abilities and promotion of discipline for'expert'ones.Conclusions:This research developed three grades of essential competencies for midwives in China.The next step will be assessment in clinical settings for further response.The set was in line with the concepts of International Confederation of Midwives under the domestic context.This set could be adopted as a reference in developing normalised midwifery practice,education and certification.

Polyisocyanuratoesters:Renewable Linear Polyesters with High Flame Retardancy

Biobased urea nowadays attracts increasing attention as a biomass resource with giant potential,which benefits from the development of biobased ammonia and ecological sanitation system.Urea is an ideal feedstock for chemical industry and developing new urea-based polymer materials can take advantage of the urea resource.In this work,a class of renewable linear polyesters,namely polyisocyanuratoesters(PICEs)were synthesized from a urea-based monomer bis(2-carbomethoxyethyl)isocyanurate and biobased aliphatic diols.Compared with conventional aliphatic polyesters,PICEs containing isocyanurate rings in the polymer chain backbone exhibit outstanding flame retardancy that both PICE-4(the number‘4’refers to the number of methylene in diols,e.g.4 for butylene and 6 for hexylene)and PICE-6 have high limiting oxygen index values over 30%.In the UL 94 tests,PICE-6 reaches V-1 rating;while V-2 is found for PICE-10.All PICEs exhibit similar pyrolysis behavior that the temperatures of 5%weight loss are around 320°C.PICEs are found to have glass transition among 20°C-45°C.No crystallization behavior is observed without annealing except for PICE-10,which can crystallize even at room temperature.

正常前列腺、前列腺癌的经直肠超声造影特点的研究(英文)

Objective:The aim of the study was to observe the characters and differences of the inner and outer parts of prostate gland, the prostatic cancer lesions in inner and outer parts of prostate glands by transrectal contrast enhanced ultrasonography (TRCEUS) in order to provide valuable information for diagnosing of prostatic cancers. Methods: The ultrasound contrast agent was SonoVue (from Bracco Company, Italian). Instrument adopted Esaote Company Technos DU8 (transrectal ultrasonography). We observed the starting and ending times of transrectal contrast enhancement in the normal prostate inner gland group (16 cases), normal prostate outer gland group (16 cases), and the prostatic cancer lesions in inner gland group (8 cases) as well as in outer gland group (11 cases), respectively. Results: There was no significant difference in the starting time of the normal prostate glands between the inner gland and outer gland groups (P>0.05), likewise no significant difference between the cancer lesions in the inner gland and outer gland groups (P>0.05), but starting times of the cancer lesions in both groups were earlier than those of the normal prostate inner and outer glands groups (P<0.01). The ending time of enhancement was no significant difference among all groups (P>0.05). Conclusion: The earlier starting time of contrast enhancement in prostatic cancer lesions by TRCEUS has important value of distinguishing the cancer lesions from normal prostate glands. It is helpful to diagnose the prostatic cancer lesions.

Synthesis and Properties of Thermoplastic Polyisocyanurates:Polyisocyanuratoamide,Polyisocyanurato(Ester-Amide)and Polyisocyanurato(Urea-Ester)

It has been proved that introducing isocyanurate into polymer chains could improve the flame retardancy of polymers.We describe in this work the synthesis and the thermal property study of three thermoplastic polyisocyanurates,which are polyisocyanuratoamide(PICA-6),polyisocyanurato(ester amide)(PICEA-6)and polyisocyanurato(urea ester)(PICUE-6).These polymers show similar and improved thermal stability with the existence of isocyanurate rings.PICA-6 is more crystalizable than the rest two and the melting temperature is found to be around 240℃ but it still crystalizes slowly.For PICEA-6 and PICUE-6,only glass transition can be observed on the DSC traces.The glass transition temperature follows the order of PICA-6>PICEA-6>PICUE-6(101.9,77.9 and 28.7℃,respectively).

Automated Chinese Essay Scoring Based on Deep Learning

Writing is an important part of language learning and is considered the best approach to demonstrate the comprehensive language skills of students.Manually grading student essays is a time-consuming task;however,it is necessary.An automated essay scoring system can not only greatly improve the efficiency of essay scoring,but also provide more objective score.Therefore,many researchers have been exploring automated essay scoring techniques and tools.However,the technique of scoring Chinese essays is still limited,and its accuracy needs to be enhanced further.To improve the accuracy of the scoring model for a Chinese essay,we propose an automated scoring approach based on a deep learning model and validate its effect by conducting two comparison experiments.The experimental results indicate that the accuracy of the proposed model is significantly higher than that of multiple linear regression(MLR),which was commonly used in the past.The three accuracy rates of the proposed model are comparable to those of the novice teacher.The root mean square error(RMSE)of the proposed model is slightly lower than that of the novice teacher,and the correlation coefficient of the proposed model is also significantly higher than that of the novice teacher.Besides,when the predicted scores are not very low or very high,the two predicted models are as good as a novice teacher.However,when the predicted score is very high or very low,the results should be treated with caution.

Design and development of an ACCT for the Shanghai advanced proton therapy facility

The Shanghai advanced proton therapy facility is a proton cancer treatment device designed and built by the Shanghai Institute of applied physics at the Chinese academy of sciences.The accelerator part comprises a proton linear accelerator(linac)injector and a circular synchrotron.An alternating current current transformer(ACCT)is used for non-intercepting beam current measurement at the drift tube linac exit.According to the beam characteristics,the ACCT is required to complete real-time beam current and pulse width measurements at currents of3-30 mA,frequencies of 1-10 Hz,and pulse widths of40-400μs.In this paper,we report the design and development of an ACCT.The designed ACCT was simulated using CST Microwave Studio,and calibrated using an oscilloscope and signal generator.Variations in the output signal of the ACCT were investigated as a function of ceramic gap size,number of coil turns,and resistance.According to the simulation and experimental results,the optimal number of coil turns was found to be 30.In addition,a low-pass filter was adopted to filter the noise introduced during long-distance signal transmission using a coaxial cable with the length of 20 m.The calibration results show that the corresponding rise time of the ACCT is 800 ns with the sensitivity of 8.2 V/A and a droop of less than 1%,meeting the design requirements.

A review of the definition and scope of practice of midwives in five representative countries

Objective: To review the definition and scope of the practice of midwives in Sweden, Finland, the United Kingdom, the United States,and Australia to find models and make suggestions for reforms in the midwifery policies of China.Methods: This article reviewed the midwifery policies published by authorities, organizations, and governments of these countries and relevant literature in the databases of PubMed, Web of Science, Cumulative Index to Nursing and Allied Health Literature(CINAHL),China National Knowledge Infrastructure(CNKI), and Wanfang database.Results: The definition and scope of practice of midwives in five representative countries and China were reviewed. The similarities and differences in midwifery policies among them show that most countries set standards based on the definition and scope of practice of midwives recommended by International Confederation of Midwives.Conclusions: The definition of midwives should include registration, midwifery education, and acceptance standards. The scope of practice of midwives should specify an autonomous environment, the objective of care, the period of care involved, prescribing rights,emergency treatment, and health counseling.

机械工业应对“双碳”的机遇与挑战

为应对全球气候变化,我国积极行动,逐步构建了碳达峰碳中和(简称“双碳”)的政策体系,对我国工业绿色低碳发展提出了更高要求^([1~6]).机械工业是我国国民经济发展的基础性产业,为国民经济各行业提供技术装备,所提供技术装备的节能低碳化是各行业实现节能降碳目标的重要保障^([7,8]).在“双碳”目标约束下,机械工业面临诸多机遇与挑战.

Strengthening and toughening bulk Ni_(2)CoFeV_(0.5) medium-entropy alloy via thermo-mechanical treatment

Single-phase face-centered cubic(fcc)medium-and high-entropy alloys(MEAs/HEAs)have high ductility but low yield strength.In this work,the microstructures of single-phase fcc Ni_(2)CoFeV_(0.5) MEAs were tailored by cold-rolling and subsequent annealing and typical heterogeneous lamella(HL)structures composed of recrystallized micro-grain lamellae(with an averaged grain size of∼4μm)and nonrecrystallized nano-/ultrafine-grain lamellae were obtained.Tensile tests revealed that most HL samples exhibited excellent strength and ductility synergy.The HL sample with∼23 vol%recrystallized grains annealed at 590℃ for 1 h had a high yield strength of 1120 MPa and a good fracture elongation of 12.3%,which increased by 5%and 46%,respectively compared with those of as-rolled sample.Annealing-induced yield strength increase is attributed to high-density annealing twin boundaries(TBs)in the recrystallized grains,the annihilation of mobile dislocations inside the non-recrystallized grains,and extra heterodeformation-induced strengthening produced by the HL structure.Hall-Petch relationship of Ni_(2)CoFeV_(0.5) MEA can be reasonably described by counting both TBs and grain boundaries,with lattice friction stress of 87.3 MPa and coefficient of 722.8 MPaμm1/2.Our work provides optional and controllable solutions for preparing MEAs/HEAs with excellent mechanical properties by low-cost and high-efficiency thermomechanical treatments.

Data-driven iterative learning trajectory tracking control for wheeled mobile robot under constraint of velocity saturation

Considering the wheeled mobile robot(WMR)tracking problem with velocity saturation,we developed a data‐driven iterative learning double loop control method with constraints.First,the authors designed an outer loop controller to provide virtual velocity for the inner loop according to the position and pose tracking error of the WMR kinematic model.Second,the authors employed dynamic linearisation to transform the dynamic model into an online data‐driven model along the iterative domain.Based on the measured input and output data of the dynamic model,the authors identified the parameters of the inner loop controller.The authors considered the velocity saturation constraints;we adjusted the output velocity of the WMR online,providing effective solutions to the problem of velocity saltation and the saturation constraint in the tracking process.Notably,the inner loop controller only uses the output data and input of the dynamic model,which not only enables the reliable control of WMR trajectory tracking,but also avoids the influence of inaccurate model identification processes on the tracking performance.The authors analysed the algorithm's convergence in theory,and the results show that the tracking errors of position,angle and velocity can converge to zero in the iterative domain.Finally,the authors used a simulation to demonstrate the effectiveness of the algorithm.

在线用工平台算法管理的消极影响和控制策略研究:算法技术属性视角

在线用工平台通过大数据和算法进行任务分配、绩效评价和奖惩激励,其在效率和工作自主性方面的优势受到广泛关注。然而,片面追求算法管理效率容易忽视其对平台从业者的消极影响。借鉴公平启发理论,本研究从算法技术属性角度探讨算法管理的消极影响,提出算法技术属性正向影响平台从业者算法不公平感、进而诱发平台工作倦怠和绩效降低的研究命题,并探讨了平台从业者参与对于算法技术属性、算法不公平感和平台工作倦怠、绩效之间关系的调节作用。本研究有助于丰富关于算法管理的消极影响形成机制和控制策略研究,并为在线用工平台算法管理如何兼顾效率和人性化提供建议。

基于超分子聚合物的自修复材料

材料的自修复功能对于材料应用具有重要的意义,如键组装/解组装常数、键的方向和链的弛豫时间等因素会影响自修复效率。根据提供修复功能的物质构成形式,可以分为外援型自修复材料和本征型自修复材料,其中本征型自修复材料是当前的热点方向,在本征型自修复材料中,超分子自修复材料以其独特的可逆性组装,以及在快速、可逆、多重响应方面的优势而成为研究重点。本文重点阐述了基于不同结合效应的超分子自修复聚合物的研究进展,并对今后的研究方向作了展望,认为材料的耐环境性能能否达标是未来能否获得应用的关键因素之一。

Platform Competition for Advertisers and Viewers in Media Markets with Endogenous Content and Advertising

In this paper,we investigate two competing pay-tv platforms or free-to-air media platforms that consist of two groups of agents:viewers and advertisers.The pay-tv platforms can receive revenues from charging viewers pay-per-view prices and advertising,while the free-to-air platforms can only obtain all incomes from advertising.We discuss and compare advertising intensities and program content provisions of the two competing media platforms.Our findings show that if the extent to which viewers dislike advertising(the nuisance for advertising)is more massive than the marginal benefit that advertisers receive from an additional viewer,the pay-tv stations tend to maximally differentiate their program content and charge the viewers higher pay-per-view prices.If the nuisance approaches to the marginal benefit,however,both stations should offer similar program content,and charge the viewers lower prices under certain conditions.Particularly,if both platforms provide duplicated content,they should subsidize the viewers.In contrast,we show that the free-to-air media platforms never duplicate program content with a positive nuisance for advertising,and tend to offer maximal differentiated content if the nuisance is sufficiently large.Moreover,we reveal that if the viewers greatly dislike advertising(care less about advertising),the advertising volume of the pay-tv platforms is lower(higher)than that of the free-to-air platforms.Finally,we extend our base model to the case in which a pay-tv platform competes against a free-to-air station,and numerically show that the profit of the pay-tv platform may be larger or smaller than that of the free-to-air station.

Tracking the reactivity of ozonation towards effluent organic matters from WWTP using two-dimensional correlation spectra

The characteristics of effluent organic matter(EfOM) from a wastewater treatment plant(WWTP) during ozonation were investigated using excitation and emission matrix(EEM)spectra, Fourier transform infrared spectroscopy(FT-IR) and high-performance size exclusion chromatography(HPSEC) at different ozone dosages. The selectivity of ozonation towards different constituents and functional groups was analysed using two-dimensional correlation spectra(2D-COS) probed by FT-IR, synchronous fluorescence spectra and HPSEC.The results indicated that ozonation can destroy aromatic structures of EfOM and change its molecular weight distribution(MWD). According to 2D-COS analysis, microbial humiclike substances were preferentially removed, and then the protein-like fractions. Terrestrial humic-like components exhibited inactivity towards ozonation compared with the above two fractions. Protein-like substances with small molecular weight were preferentially reacted during ozonation based on 2D-COS probed by HPSEC. In addition, the selectivity of ozone towards different functional groups of EfOM exhibited the following sequence:phenolic and alcoholic C\O groups > aromatic structures containing C_C double bonds >aliphatic C\H. X-ray photoelectron spectroscopy(XPS) further elucidated the preferential reaction of aromatic structures in EfOM during ozonation.

Total pancreatic necrosis after organophosphate intoxication

Cases of acute pancreatitis induced by organophosphate intoxication are encountered occasionally in clinics, but very few of them develop into severe pancreas necrosis and irreversible pancreatic function impairment. Here, we report a 47-year-old female organophosphate poisoning case after ingestion of massive insecticides;she was considered to have total necrosis and function failure of the pancreas via serum amylase test, glucose level test, and CT imaging. The patient exhibited no relief under the regular medicine treatment, which included sandostatin, antibiotics, intravenous atropine, and pralidoxime methiodide. She received percutaneous catheterization and drainage of pancreatic zone to expel hazardous necrotic waste, also by which the pathogenic evidence was obtained and the antibiotics were adjusted subsequently. The patient recovered gradually, was discharged after 2 weeks, and was prescribed with oral pancreatin capsules before meals and hypodermic insulin at meals and bedtime to compensate the impaired pancreatic function.

Comparative proteomics analysis of Pichia pastoris cultivating in glucose and methanol

The methylotrophic yeast Pichia pastoris(syn.Komagataella phaffii)has been extensively engineered for protein production,and is attracting attention as a chassis cell for methanol biotransformation toward production of small molecules.However,the relatively unclear methanol metabolism hampers the metabolic rewiring to improve the biosynthetic efficiency.We here performed a label-free quantitative proteomic analysis of Pichia pastoris when cultivated in minimal media containing methanol and glucose,respectively.There were 243,158 up-regulated proteins and 244,304 down-regulated proteins in log and stationary phase,respectively,when cultivated in methanol medium compared with that of glucose medium.Peroxisome enrichment further improved the characterization of more differentially expressed proteins(481 proteins in log phase and 524 proteins in stationary phase).We demonstrated the transaldolase isoenzyme(Tal2,Protein ID:C4R244)was highly up-regulated in methanol medium cultivation,which plays an important role in methanol utilization.Our work provides important information for understanding methanol metabolism in methyltrophic yeast and will help to engineer methanol biotransformation in P.pastoris.

A Novel Probabilistic Saturating Counter Design for Secure Branch Predictor

In a modern processor,branch prediction is crucial in effectively exploiting the instruction-level parallelism for high-performance execution.However,recently exposed vulnerabilities reveal the urgency to improve the security of branch predictors.The vital cause of the branch predictor vulnerabilities is that the update strategy of the saturating counter is deterministic.As a fundamental building block in a modern branch predictor,previous studies have paid too much attention to the performance and hardware cost and ignored the security of saturating counter.This leaves attackers with the opportunities to perform side-channel attacks on the branch predictor.This paper focuses on the saturating counter to explore a secure and lightweight design to mitigate branch predictor side-channel attacks.Instead of applying the isolation mechanism to branch predictor resources,we propose a novel probabilistic saturating counter design to confuse the attacker's perception of the victim's behaviour.It changes the conventional deterministic state transition function to a probabilistic state transition function.When a branch is committed,the conventional saturating counter needs to be updated about whether the prediction results are correct or not.While for the probabilistic saturating counter,the branch predictor determines whether the update is performed based on the update probability.The probabilistic saturating counter dramatically reduces the ability of the attacker to spy the saturating counter's state.Our analyses using a cycle-accurate simulator suggest that the proposed mechanism incurs 2.4%performance overhead and hardware cost while providing strong protection.

Single-cell technologies:From research to application

In recent years,more and more single-cell technologies have been developed.A vast amount of single-cell omics data has been generated by large projects,such as the Human Cell Atlas,the Mouse Cell Atlas,the Mouse RNA Atlas,the Mouse ATAC Atlas,and the Plant Cell Atlas.Based on these single-cell big data,thousands of bioinformatics algorithms for quality control,clustering,cell-type annotation,developmental inference,cell-cell transition,cell-cell interaction,and spatial analysis are developed.With powerful experimental single-cell technology and state-of-the-art big data analysis methods based on artificial intelligence,the molecular landscape at the single-cell level can be revealed.

Security-first architecture:deploying physically isolated active security processors for safeguarding the future of computing

It is fundamentally challenging to build a secure system atop the current computer architecture.The complexity in software,hardware and ASIC manufacture has reached beyond the capability of existing verification methodologies.Without whole-system verification,current systems have no proven security.It is observed that current systems are exposed to a variety of attacks due to the existence of a large number of exploitable security vulnerabilities.Some vulnerabilities are difficult to remove without significant performance impact because performance and security can be conflicting with each other.Even worse,attacks are constantly evolving,and sophisticated attacks are now capable of systematically exploiting multiple vulnerabilities while remain hidden from detection.Eagering to achieve security hardening of current computer architecture,existing defenses are mostly ad hoc and passive in nature.They are normally developed in responding to specific attacks spontaneously after specific vulnerabilities were discovered.As a result,they are not yet systematic in protecting systems from existing attacks and likely defenseless in front of zero-day attacks.To confront the aforementioned challenges,this paper proposes Security-first Architecture,a concept which enforces systematic and active defenses using Active Security Processors.In systems built based on this concept,traditional processors(i.e.,Computation Processors)are monitored and protected by Active Security Processors.The two types of processors execute on their own physically-isolated resources,including memory,disks,network and I/O devices.The Active Security Processors are provided with dedicated channels to access all the resources of the Computation Processors but not vice versa.This allows the Active Security Processors to actively detect and tackle malicious activities in the Computation Processors with minimum performance degradation while protecting themselves from the attacks launched from the Computation Processors thanks to the resource isolation.