Three dimensional phase-field simulation for non-isothermal binary alloy solidification: Comparison with LKT theory

Using the advanced algorithm combining parallel computing,adaptive mesh re-griding and multigrid methods,quantitative 3D phase-field simulations of non-isothermal solidification of binary alloy were carried out.The 3D phase-field simulation results were compared with the analytical LKT(Lipton,Kurz and Trivedi)theory.For comparison,the simulation and analytical results for 2D cases were also given.The 3D phase-field simulation results support the transport portion of the LKT theory.However,the tip radius and tip velocity predicted by the simulations are not in good agreement with the LKT theory over the whole range of undercooling.The stability parameter calculated from phase-field simulations varies significantly with the Peclet number,indicating that the stability criterion,which assumes that the stability parameter is constant,is invalid.

Patterns and drivers of plant sexual systems in the dry-hot valley region of southwestern China

Sexual systems play important roles in angiosperm evolution and exhibit substantial variations among different floras. Thus, studying their evolution in a whole flora is crucial for understanding the formation and maintenance of plant biodiversity and predicting its responses to environmental change. In this study, we determined the patterns of plant sexual systems and their associations with geographic elements and various life-history traits in dry-hot valley region of southwestern China, an extremely vulnerable ecosystem. Of the 3166 angiosperm species recorded in this area, 74.5% were hermaphroditic,13.5% were monoecious and 12% were dioecious, showing a high incidence of diclinous species. Diclinous species were strongly associated with tropical elements, whereas hermaphroditic species were strongly associated with temperate and cosmopolitan elements. We also found that hermaphroditism was strongly associated with showy floral displays, specialist entomophily, dry fruits and herbaceous plants.Dioecy was strongly associated with inconspicuous, pale-colored flowers, generalist entomophily, fleshy fruits, and woody plants, whereas monoecy was strongly associated with inconspicuous, pale-colored flowers, anemophily, dry fruits, and herbaceous plants. In addition, hermaphroditic species with generalist entomophily tended to flower in the dry season, whereas diclinous species with specialist entomophily tended to flower in the rainy season. However, independent of sexual systems, plants that produce dry fruits tended to flower in the rainy season and set fruits in the dry season, but the opposite pattern was found for fleshy fruit-producing plants. Our results suggest that in the dry-hot valleys, plant sexual systems are associated with geographic elements as well as various life-history traits that are sensitive to environmental change.

A Hierarchical Method for Locating the Interferometric Fringes of Celestial Sources in the Visibility Data

In source detection in the Tianlai project,locating the interferometric fringe in visibility data accurately will influence downstream tasks drastically,such as physical parameter estimation and weak source exploration.Considering that traditional locating methods are time-consuming and supervised methods require a great quantity of expensive labeled data,in this paper,we first investigate characteristics of interferometric fringes in the simulation and real scenario separately,and integrate an almost parameter-free unsupervised clustering method and seeding filling or eraser algorithm to propose a hierarchical plug and play method to improve location accuracy.Then,we apply our method to locate single and multiple sources’interferometric fringes in simulation data.Next,we apply our method to real data taken from the Tianlai radio telescope array.Finally,we compare with unsupervised methods that are state of the art.These results show that our method has robustness in different scenarios and can improve location measurement accuracy effectively.

Exploring Sulfur Chemistry in TMC-1 with NSRT

There have been several studies on sulfur depletion in dense cores like TMC-1(Taurus Molecular Cloud 1),employing updated reaction networks for sulfur species to explain the missing sulfur in the gas within dense clouds.Most of these studies used a C/O ratio of 0.7 or lower.We present NSRT(NanShan 26m Radio Telescope)observations of TMC-1 alongside results from time-dependent chemical simulations using an updated chemical network.Our findings highlight the impact of the C/O ratio on the gas-phase evolution of C2S and C3S.The simulation results show that the C/O ratio is an important parameter,playing a fundamental role in determining the gas-phase abundances of sulfur species in dense cores.

Numerical investigation on aerodynamic performance of a bionic flapping wing

This paper numerically studies the aerodynamic performance of a bird-like bionic flapping wing.The geometry and kinematics are designed based on a seagull wing,in which flapping,folding,swaying,and twisting are considered.An in-house unsteady flow solver based on hybrid moving grids.is adopted for unsteady flow simulations.We focus on two main issues in this study,i.e.,the influence of the proportion of down-stroke and the effect of span-wise twisting.Numerical results show that the proportion of downstroke is closely related to the efficiency of the flapping process.The preferable proportion is about 0.7 by using the present geometry and kinematic model,which is very close to the observed data.Another finding is that the drag and the power consumption can be greatly reduced by the proper span-wise twisting.Two cases with different reduced frequencies are simulated and compared with each other.The numerical results show that the power consumption reduces by more than 20%,and the drag coefficient reduces by more than 60% through a proper twisting motion for both cases.The flow mechanism is mainly due to controlling of unsteady flow separation by adjusting the local effective angle of attack.These conclusions will be helpful for the high-performance micro air vehicle (MAV) design.

NOMA-Based Energy-Efficient Task Scheduling in Vehicular Edge Computing Networks: A Self-Imitation Learning-Based Approach

Mobile Edge Computing(MEC)is promising to alleviate the computation and storage burdens for terminals in wireless networks.The huge energy consumption of MEC servers challenges the establishment of smart cities and their service time powered by rechargeable batteries.In addition,Orthogonal Multiple Access(OMA)technique cannot utilize limited spectrum resources fully and efficiently.Therefore,Non-Orthogonal Multiple Access(NOMA)-based energy-efficient task scheduling among MEC servers for delay-constraint mobile applications is important,especially in highly-dynamic vehicular edge computing networks.The various movement patterns of vehicles lead to unbalanced offloading requirements and different load pressure for MEC servers.Self-Imitation Learning(SIL)-based Deep Reinforcement Learning(DRL)has emerged as a promising machine learning technique to break through obstacles in various research fields,especially in time-varying networks.In this paper,we first introduce related MEC technologies in vehicular networks.Then,we propose an energy-efficient approach for task scheduling in vehicular edge computing networks based on DRL,with the purpose of both guaranteeing the task latency requirement for multiple users and minimizing total energy consumption of MEC servers.Numerical results demonstrate that the proposed algorithm outperforms other methods.

Smart City Development in China: One City One Policy

China is in a process of urbanization and is aiming at a type of people-centered urbanization. The main purpose of developing a ＂smart city＂ is to help this type urbanization and to serve the people of the city. From 2012 to 2015, China has chosen more than 300 cities or towns to be national pilot ＂smart cities.＂ These pilot smart cities are located in more than 30 provinces around China, which differ greatly in thousands ways. So we advocated ＂One City One Policy＂. In 2012, MOHURD announced 90 cities as first batch of pilot smart cities. After three years, some pilot cities achieved great progress. This paper introduces five example cities （including town, district） as five different models of China＇ s smart city development. They are- Guilin city; Yunlong demonstration zone; Panyu District; Yangling Agricultural Hi-tech Industries Demonstration Zone; Lecong town. This paper also introduces our standardization work on smart city field at present.

Does pollinator dependence decrease along elevational gradients?

Plants have long been thought to be less dependent on pollinators for seed production at higher elevations due to adverse pollination environments.However,recent research has yet to consistently support the generality of this expectation.In this study,we asked whether pollinator dependence decreases along an elevational gradient and how it varies with various reproductive traits.To answer these questions,we quantified pollinator-plant associations and various reproductive traits for 112 flowering plants spanning a large elevational gradient(990-4260 m a.s.l.)in the Qinghai-Tibet Plateau.We found that flowering plants in the Qinghai-Tibet Plateau region are highly dependent on pollinators for seed production(76.2%of seed production was contributed by animal pollinators and 44.6%of plants would produce no seed without pollinator visitation).Contrary to our expectation,there was no significant elevational gradient in pollinator dependence index.Although the pollinator dependence index was not significantly correlated with pollen limitation,flower size,floral longevity,or reward type,it was correlated with compatibility status and flowering time.These findings indicate that pollinator dependence does not decrease along an elevational gradient in the Qinghai-Tibet Plateau.Our study also highlights the severe vulnerability of flowering plant seed production to pollinator declines under global change in the Qinghai-Tibet Plateau region,particularly for early-flowering or self-incompatible plants growing at higher elevations(e.g.,subnival belt).

Recent advances in visible light-mediated chemical transformations of enaminones

Enaminones,which possesses both the nucleophilic enamine as well as electrophilic enone structures,are well known versatile building blocks in organic synthesis.Meanwhile,visible light-mediated reactions have emerged as useful synthetic strategy with enhanced sustainability.Around the last decade,various photochemical transformations of enaminones have been developed to construct cyclic or acyclic compounds.In this review,we describe the recent advances in visible light-mediated chemical transformations of enaminones.Detailed discussion on the reaction mechanism of the related reactions is given to provide guide to the reader.Finally,a summary on the existing challenges and the future outlook towards the development of practical photocatalytic reactions of enaminones is also presented.

Antagonistic MADS-box transcription factors SEEDSTICK and SEPALLATA3 form a transcriptional regulatory network that regulates seed oil accumulation

Transcriptional regulation is essential for balancing multiple metabolic pathways that influence oil accumulation in seeds.Thus far,the transcriptional regulatory mechanisms that govern seed oil accumulation remain largely unknown.Here,we identified the transcriptional regulatory network composed of MADS-box transcription factors SEEDSTICK(STK)and SEPALLATA3(SEP3),which bridges several key genes to regulate oil accumulation in seeds.We found that STK,highly expressed in the developing embryo,positively regulates seed oil accumulation in Arabidopsis(Arabidopsis thaliana).Furthermore,we discovered that SEP3 physically interacts with STK in vivo and in vitro.Seed oil content is increased by the SEP3 mutation,while it is decreased by SEP3 overexpression.The chromatin immunoprecipitation,electrophoretic mobility shift assay,and transient dual-luciferase reporter assays showed that STK positively regulates seed oil accumulation by directly repressing the expression of MYB5,SEP3,and SEED FATTY ACID REDUCER 4(SFAR4).Moreover,genetic and molecular analyses demonstrated that STK and SEP3 antagonistically regulate seed oil production and that SEP3 weakens the binding ability of STK to MYB5,SEP3,and SFAR4.Additionally,we demonstrated that TRANSPARENT TESTA 8(TT8)and ACYL-ACYL CARRIER PROTEIN DESATURASE 3(AAD3)are direct targets of MYB5 during seed oil accumulation in Arabidopsis.Together,our findings provide the transcriptional regulatory network antagonistically orchestrated by STK and SEP3,which fine tunes oil accumulation in seeds.

Market-based solution in China to finance the clean from the dirty

Financial incentives play a key role in promoting renewable energy investments that can help China achieve the‘dual carbon’goal.The national emissions trading scheme(ETS)and the renewable energy portfolio standard(RPS)are two existing market-based policy instruments that can generate stable expected returns for low-carbon projects.This paper studies the interactive distribution effects of these two market-based instruments.We use the micro-level thermal power plant data to investigate the abatement effects of the national ETS,in which the details show that the existing rate-based ETS will result in higher negative impacts on power units,whose installed capacities are smaller than 400 MW.The interactive distribution effects between the two markets will occur when the permit allocation standards of the national ETS become stricter than the existing ones.Provinces in Eastern China and Northern China will face high pressure on costs in both ETS and RPS markets.When the levels of the permit allocation standards are set as 70%of the existing ones and the carbon price is assumed to be 200 yuan/ton in 2030,the annual market size of the national ETS will be nearly 100 billion yuan,and the annual market size is predicted to be 250 billion yuan.In the existing rate-based national ETS,the China Certified Emission Reduction(CCER)mechanism will have an offsetting effect,which should be taken into serious consideration during the policy-making processes in the future.

不同体重指数腹膜透析患者的预后分析

目的探讨不同体重指数(BMI)腹膜透析(PD)患者的预后情况。方法选取2011年7月-2016年12月于成都医学院第一附属医院开始行持续非卧床腹膜透析(CAPD)治疗患者,按BMI分为低体重组(<20 kg/m2),正常组(≥20 kg/m2~<25 kg/m2)及超重组(≥25 kg/m2),分析3组患者的生存情况及腹膜透析相关性腹膜炎发生率,分析患者BMI与临床指标的相关性,并对不同临床指标进行比较分析。结果 3组患者生存率比较有差异(P <0.05),3组患者腹膜炎发生率比较有差异(P <0.05),BMI与24 h尿量、TG、GLU及总尿素清除率呈正相关(P <0.05),与腹膜尿素清除指数呈负相关(P <0.05)。3组患者24 h尿量、总体水、腹膜尿素清除指数、总尿素清除率及TG比较有差异(P<0.05)。结论不同BMI的PD患者具有不同的预后,众多临床因素的参与导致了超重及低体重均不利于患者的长期生存,应将PD患者的BMI控制在适当范围内。

慢病毒载体对MDA-MB-231细胞中microRNA-18a-3P表达的影响

目的构建人microRNA-18a-3P(miR-18a-3P)过表达及干扰慢病毒载体,研究病毒感染人乳腺癌细胞系MDA-MB-231的步骤和方法。方法 PCR技术扩增相应目的基因片段并进行酶切,回收后与目的基因连接,产物转化细菌感受态细胞,对阳性克隆测序行对比分析,构建miR-18a-3P过表达及干扰慢病毒载体,荧光法测定病毒滴定;倒置荧光显微镜观察人乳腺癌细胞MDA-MB-231转染及筛选过程的转染效率,筛选最佳MOI值;qRT-PCR检测慢病毒转染后MDA-MB-231细胞内miR-18a-3P的表达。结果测序分析证实重组慢病毒构建正确;过表达及干扰慢病毒滴度分别为2×10~9和1×10~9 TU/ml;加Polybrene较未加Polybrene转染效率升高,当感染复数为10 TU/ml,Polybrene浓度为1μg/ml时,转染效率最佳;miR-18a-3P转染组过表达miR-18a-3P的相对表达量较空白对照组、阴性对照组高(P<0.05),miR-18a-3P转染组干扰表达miR-18a-3P的相对表达量较空白对照组、阴性对照组低(P<0.05)。结论成功构建了miR-18a-3P过表达及干扰慢病毒表达载体,对人乳腺癌细胞MDA-MB-231进行转染和筛选后,可快速高效率获得所需目的细胞。

老年睑板腺功能障碍蠕形螨感染率及茶树精油联合氟米龙的疗效

目的:研究老年睑板腺功能障碍(MGD)蠕形螨感染率及茶树精油联合氟米龙的疗效。方法:回顾性病例对照研究。选择2017-09/2018-03在宁波市眼科医院门诊就诊的老年MGD患者59例118眼。将睫毛蠕形螨镜检为阳性的38例患者76眼进行症状评分、蠕形螨数量、泪膜破裂时间(BUT)、角膜荧光素染色(FL)、Schirmer I试验(SIaT)等检查,并按不同治疗方法分成3组,A组使用0.02%氟米龙滴眼液滴眼24眼;B组使用茶树精油(TTO)湿巾敷眼26眼;C组用0.02%氟米龙滴眼液滴眼联合TTO湿巾敷眼26眼,随访4wk。结果:118眼中76眼(64.4%)睫毛蠕形螨镜检为阳性。睫毛蠕形螨阳性的三组患者治疗后的主观症状评分均较治疗前有改善(P<0.05)。治疗后A组蠕形螨数量较治疗前无显著差异(P=0.11);B、C组较治疗前明显减少(均P<0.01)。三组患者BUT治疗前后比较,A组BUT无显著差异(P=0.22);B、C组BUT明显延长(均P<0.05)。治疗后C组的BUT较A、B组明显延长(均P<0.05)。三组患者治疗前后的FL评分均较治疗前明显改善(P<0.05)。结论:老年MGD患者睫毛蠕形螨感染率较高,睑板腺热疏通后TTO湿巾联合0.02%氟米龙滴眼液能有效驱螨、缓解MGD患者局部症状。

Blockchain Data Privacy Access Control Based on Searchable Attribute Encryption

Data privacy is important to the security of our society,and enabling authorized users to query this data efficiently is facing more challenge.Recently,blockchain has gained extensive attention with its prominent characteristics as public,distributed,decentration and chronological characteristics.However,the transaction information on the blockchain is open to all nodes,the transaction information update operation is even more transparent.And the leakage of transaction information will cause huge losses to the transaction party.In response to these problems,this paper combines hierarchical attribute encryption with linear secret sharing,and proposes a blockchain data privacy protection control scheme based on searchable attribute encryption,which solves the privacy exposure problem in traditional blockchain transactions.The user’s access control is implemented by the verification nodes,which avoids the security risks of submitting private keys and access structures to the blockchain network.Associating the private key component with the random identity of the user node in the blockchain can solve the collusion problem.In addition,authorized users can quickly search and supervise transaction information through searchable encryption.The improved algorithm ensures the security of keywords.Finally,based on the DBDH hypothesis,the security of the scheme is proved in the random prediction model.

High-efficient solar-driven hydrogen production by full-spectrum synergistic photo-thermo-catalytic methanol steam reforming with in-situ photoreduced Pt-CuO_(x) catalyst

Synergy between the intrinsic photon and thermal effects from full-spectrum sunlight for H_(2) production is considered to be central to further improve solar-driven H_(2) production.To that end,the photo-thermocatalyst that demonstrates both photoelectronic and photothermal conversion capabilities have drawn much attention recently.Here,we propose a novel synergistic full-spectrum photo-thermo-catalysis technique for high-efficient H_(2) production by solar-driven methanol steam reforming(MSR),along with the Pt-Cu Oxphoto-thermo-catalyst featuring Pt-Cu/Cu_(2)O/CuO heterojunctions by Pt-mediated in-situ photoreduction of Cu O.The results show that the H_(2) production performance rises superlinearly with increasing light intensity.The optimal H_(2) production rate of 1.6 mol g^(-1) h^(-1) with the corresponding solar-to-hydrogen conversion efficiency of 7%and the CO selectivity of 5%is achieved under 15×sun full-spectrum irradiance(1×sun=1 k W m^(-2))at 180°C,which is much more efficient than the previously-reported Cu-based thermo-catalysts for MSR normally operating at 250~350°C.These attractive performances result from the optimized reaction kinetics in terms of intensified intermediate adsorption and accelerated carrier transfer by long-wave photothermal effect,and reduced activation barrier by short-wave photoelectronic effect,due to the broadened full-spectrum absorbability of catalyst.This work has brought us into the innovative technology of full-spectrum synergistic photothermo-catalysis,which is envisioned to expand the application fields of high-efficient solar fuel production.

周细胞在脑卒中发病机制中的作用

脑卒中是一种突发的脑血液循环障碍性疾病,研究表明星形胶质细胞和小胶质细胞在脑卒中发病机制中扮演了重要的角色,周细胞在脑卒中的进展和痊愈中也发挥了重要的作用。作为周围血管的多潜能细胞和参与血脑屏障(BBB)的主要细胞成分,周细胞具有包括作为干细胞和祖细胞,维持BBB完整性等多种功能。该文将对周细胞在脑卒中发病机制中的作用,尤其是影响脑血流、BBB完整性、血管发生、免疫反应、疤痕形成及纤维化等方面作一个综述。

Numerical simulation of microstructure evolution and microsegregation of U-Nb alloy during solidification process

In this work, a cellular automaton model has been developed to simulate the microstructure evolution of U-Nb alloy during the solidification process. The preferential growth orientation, solute redistribution in both liquid and solid, solid/liquid interface solute conservation, interface curvature and the growth anisotropy were considered in the model. The model was applied to simulate the dendrite growth and Nb microsegregation behavior of U-5.5 Nb alloy during solidification, and the predicted results showed a reasonable agreement with the experimental results. The effects of cooling rates on the solidification microstructure and composition distribution of U-5.5 Nb were investigated by using the developed model. The results show that with the increase of the cooling rate, the average grain size decreases and the Nb microsegregation increases.

Prognostic significance of PD-L1 expression in patients with colorectal cancer: a meta-analysis

Background The association between the expression of programmed cell death 1(PD-1) or its ligand [programmed cell death ligand-1(PD-L1)] and colorectal cancer(CRC) survival rates remains unclear. Thus, we conducted a meta-analysis to investigate the prognostic value of PD-L1 expression in CRC patients.Methods All eligible studies related to evaluation of PD-L1 expression and survival of CRC patients were searched in PubMed, Medline, Cochrane library, and the EMBASE database. Hazard ratios(HRs) and 95% confidence intervals(CI) of overall survival(OS) were examined to assess the effect of PD-L1 expression on the survival of CRC patients. The outcomes of this meta-analysis were synthesized based on randomeffects model. Subgroup analyses were also performed. Results Seven studies, wherein OS data were stratified according to the expression status of PD-L1, were analyzed. CRC patients showing positive PD-L1 expression were associated with significantly poorer prognoses in terms of overall survival, compared with those displaying negative PD-L1 expression(HR = 1.43, 95% CI: 1.07–1.92; P = 0.02). In the subgroup analyses, H-scores as well as the percentage of stained cells indicated that PD-L1 expression was significantly associated with poor prognosis(HR = 1.90, 95% CI: 1.38–2.62, P < 0.01; HR = 1.81, 95% CI: 1.08–3.03, P = 0.02). Immunohistochemical staining, utilizing a rabbit anti-PD-L1 antibody, revealed significantly superior survival in the PD-L1 negative group compared with the PD-L1 positive expression group(HR = 1.92; 95% CI, 1.40-2.63; P < 0.01). Moreover, PD-L1 expression was significantly associated with poor prognosis when polyclonal antibodies were used(HR = 1.84; 95% CI, 1.30–2.61; P < 0.01). Conclusion Our meta-analysis indicated that PD-L1 expression status is a significant prognostic factor for CRC patients. Positive PD-L1 expression was associated with worse CRC survival. Evaluation via different immunohistochemistry based techniques may partly account for the contradictory results. Therefore, further investigative studies using larger sample sizes are felt to be needed to elucidate the prognostic value of PD-L1 expression in CRC patients.

Variation characteristics of CO_(2) in a newly-excavated soil profile,Chinese Loess Plateau:Excavation-induced ancient soil organic carbon decomposition

Soils of the Chinese Loess Plateau(CLP)contain substantial amounts of soil inorganic carbon(SIC),as well as recent and ancient soil organic carbon(SOC).With the advent of the Anthropocene,human perturbation,including excavation,has increased soil CO_(2) emission from the huge loess carbon pool.This study aims to determine the potential of loess CO_(2) emission induced by excavation.Soil CO_(2) were continuously monitored for seven years on a newly-excavated profile in the central CLP and the stable C isotope compositions of soil CO_(2) and SOC were used to identify their sources.The results showed that the soil CO_(2) concentrations ranged from 830μL·L^(-1) to 11190μL·L^(-1) with an annually reducing trend after excavation,indicating that the human excavation can induce CO_(2) production in loess profile.Theδ^(13) C of CO_(2) ranged from–21.27‰to–19.22‰(mean:–20.11‰),with positive deviation from top to bottom.The range of δ^(13)CSOC was–24.0‰to–21.1‰with an average of–23.1‰.Theδ^(13) C-CO_(2) in this study has a positive relationship with the reversed CO_(2) concentration,and it is calculated that 80.22%of the soil CO_(2) in this profile is from the microbial decomposition of SOC and 19.78%from the degasification during carbonate precipitation.We conclude that the human excavation can significantly enhance the decomposition of the ancient OC in loess during the first two years after perturbation,producing and releasing soil CO_(2) to atmosphere.