Guaranteed Cost Attitude Tracking Control for Uncertain Quadrotor Unmanned Aerial Vehicle Under Safety Constraints

In this paper,guaranteed cost attitude tracking con-trol for uncertain quadrotor unmanned aerial vehicle(QUAV)under safety constraints is studied.First,an augmented system is constructed by the tracking error system and reference system.This transformation aims to convert the tracking control prob-lem into a stabilization control problem.Then,control barrier function and disturbance attenuation function are designed to characterize the violations of safety constraints and tolerance of uncertain disturbances,and they are incorporated into the reward function as penalty items.Based on the modified reward function,the problem is simplified as the optimal regulation problem of the nominal augmented system,and a new Hamilton-Jacobi-Bellman equation is developed.Finally,critic-only rein-forcement learning algorithm with a concurrent learning tech-nique is employed to solve the Hamilton-Jacobi-Bellman equa-tion and obtain the optimal controller.The proposed algorithm can not only ensure the reward function within an upper bound in the presence of uncertain disturbances,but also enforce safety constraints.The performance of the algorithm is evaluated by the numerical simulation.

The tri-band high spectral resolution spectrometer with gratings in tandem for the charge-exchange recombination spectroscopy diagnostic system on HL-2A tokamak

Charge-exchange(CX) recombination spectroscopy is a powerful tool monitoring ion temperature and plasma rotation with good temporal and spatial resolutions. A compact, new design for a high-throughput, tri-band high spectral resolution spectrometer has been developed for the charge-exchange recombination spectroscopy measurement on the HL-2A tokamak. The simultaneous measurements of He II(468.57 nm), C VI(529.1 nm), and Dα(656.1 nm accompanied by beam emission spectra) with an acquisition frequency up to 400 Hz are achieved by vertically binning the spectrum from each fiber in experiments. Initial results indicate that the system can provide radial profiles of not only ion temperature and rotation velocity,but also concentration of carbon. For the case of helium, the measurements for the ion temperature and rotation velocity are straightforward but the apparent concentration associated with the observed CX intensity is obviously too high. Modeling of the active He II CX feature including plume contributions needs to be carried out to extract the true helium concentration.The spectrometer could become a prototype for the ITER charge-exchange recombination spectroscopy diagnostic and the pilot experiments, as presented here, demonstrate the possibility of impurity concentrations measurements based on the combined measurement of local beam emission and charge-exchange recombination spectroscopy spectra.

In-situ transformation of Co(OH)_(2) into NH_(4)CoPO_(4)·H_(2)O on Co foil: 3D self-supported electrocatalyst with asymmetric local atomic and electronic structure for enhanced oxygen evolution reaction

Development of high efficient and stable water oxidation catalysts is essential for the realization of industrial water-splitting systems. Herein, a novel approach involving an in-situ transformation of Co(OH)2 nanosheets into NH4 CoPO4·H2 O nanoplates on Co foil is reported. As a 3 D self-supported oxygen revolution reaction(OER) electrocatalyst, the as-prepared NH4 CoPO4·H2 O/Co exhibits remarkable catalytic activity and exceptional stability. Specifically, it can deliver a current density of 10 m A cm^(-2) at a quite low overpotential of 254 m V with a small Tafel slope of 64.4 m V dec-1 in alkaline electrolyte. Through experimental study and theoretical analysis, the excellent OER performance can be attributed to enriched exposed active sites, favorable electron/proton transfer and mass transport, and its unique asymmetric local atomic and electronic structure. Thus, this present research not only provides a practicable in-situ transformation strategy to design 3 D self-supported electrocatalysts, but also enlightens a new way of developing transition-metal phosphates for efficient and stable water oxidation at atomic level.

Long-term effect of clopidogrel in patients with and without diabetes: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND Previous studies have shown that patients with diabetes mellitus(DM) respond poorly to clopidogrel treatment.AIM To systematically evaluate the efficacy of clopidogrel for the treatment of acute coronary syndromes or ischemic stroke in patients with or without DM.METHODS Pub Med,the Cochrane Central Register of Controlled Trials,and EMBASE were searched from 1980 on 27 June 2019 to identify relevant randomized controlled trials that compared the effect of a combination of clopidogrel and aspirin with aspirin alone.A random-effects meta-analysis was used to estimate the hazard ratio(HR) and its 95% confidence interval(CI).Sensitivity analysis was performed using a fixed-effect model.The I2 statistic was used to evaluate the heterogeneity of the study data.RESULTS Six randomized controlled trials,comprising 43352 participants(13491 with and 29861 without DM) who had received antiplatelet therapy for≥3 mo,were included in the meta-analysis.Compared with aspirin alone,a combination of clopidogrel and aspirin significantly reduced the risk of any cardiovascular event in patients without DM(HR=0.78,95%CI:0.71–0.86,P<0.001;I2=23%,P=0.26).Clopidogrel plus aspirin also significantly reduced cardiovascular risk in patients with DM,although the effect was smaller(HR=0.89,95%CI:0.81–0.99,P=0.030;I2=0%,P=0.74).Nevertheless,there was no significant difference in the efficacy of clopidogrel at reducing the risk of cardiovascular events in patients with DM vs those without(P for interaction=0.062).CONCLUSION Thus,the present study shows that the addition of clopidogrel to aspirin significantly lowers cardiovascular risk in patients with or without DM who have experienced ischemic cardiovascular disease.The beneficial effect of the addition of clopidogrel to aspirin for patients with DM was lower than that in patients without DM,although the modifying effect of DM did not reach significance.

Tunable Electronic and Optical Properties of 2D Monoelemental Materials Beyond Graphene for Promising Applications

As a new type of two-dimensional(2D)materials,monoelemental 2D materials have the atomic structure similar to graphene,and their excellent optical and electronic properties have potential applications in many fields.To date,many studies based on monoelemental 2D materials have been reported,and excellent performance has been demonstrated in various fields.The monoelemental 2D materials that have been reported so far are mainly distributed in the groupⅢA,ⅣA,ⅤA,andⅥA.Because of their structural similarities to graphene,they are commonly referred to as"Xenes."Here,we have comprehensively reviewed the research progress of monoelemental 2D materials.In this review,we explore the structure,properties,and practical applications of these monoelemental 2D materials.First,the classification,structural features,optical properties,electronic characteristics,and regulating mechanism of these monoelemental 2D materials are introduced.Then,the practical application and research progress of monoelemental 2D materials in various fields are reviewed comprehensively,especially including photoelectric catalysis,solar cells,and other energy fields.This review will give readers a more all-sided understanding of monoelemental 2D materials and have some guiding significance for their further development.

失活X染色体基因逃逸与系统性红斑狼疮的性别二态性

X染色体失活可平衡女性中两条X染色体的基因剂量。越来越多的证据表明,失活X染色体上存在许多能够逃逸失活的基因。逃逸的机制涉及到DNA、RNA、组蛋白的表观修饰以及众多的调控蛋白和染色质的空间结构。失活X染色体基因逃逸的研究为人类疾病(特别是自身免疫性疾病)性别二态性的研究开辟了新的途径。目前已证实包括TLR7、CD40L、IRAK-1、CXCR3、CXorf21等失活X染色体基因逃逸是系统性红斑狼疮(systemic lupus erythematosus,SLE)女性好发的重要原因。本文主要综述了失活X染色体上基因逃逸以及与SLE性别二态性形成的分子机制。阐明SLE性别二态性形成的分子机制,不仅对疾病的诊断、治疗具有重要意义,而且对深入揭示人类免疫系统的发育及调控机理也有重要的理论意义。

Effects of ozone water irrigation and spraying on physiological characteristics and gene expression of tomato seedlings

Tomato seedlings were used as experimental materials and treated with 1.0,2.0,3.0,and 4.0 mg/L ozone water irrigation and 0.2,0.4,0.6,and 0.8mg/L ozone water spray treatments.Indexes including the malondialdehyde(MDA)content,superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT),activities,soil and plant analysis development(SPAD)value,and nitrogen content of leaves were measured.Furthermore,the expression of antioxidant enzyme,chlorophyll synthesis and nitrogen absorption genes was analyzed after optimal ozone water treatment.The results showed that the activities of antioxidant enzymes in tomato leaves were significantly increased,and the MDA content in tomato leaves was significantly reduced by ozone water irrigation and spray treatment,which indicated that ozone water treatment can significantly improve the stress tolerance of tomato seedlings.Ozone water irrigation and spraying could also significantly increase the leaf SPAD value and nitrogen content of tomato seedlings,and the optimal concentrations of ozone water irrigation and spraying were 3.0mg/L and 0.6 mg/L,respectively.The effect of ozone water irrigation on improving the physiological characteristics of tomato seedlings was better than that of spraying.After treatment with the optimal concentration of ozone water,the relative expression of antioxidant enzyme,chlorophyll synthesis,and nitrogen absorption genes was significantly increased,and the maximum expression level was reached at 12h.In addition,ozone water irrigation could promote the expression of genes more than ozone water spraying,which was consistent with the improvements in the physiological characteristics of the tomato seedlings.

Effects of sorafenib and regorafenib on the expression of hypoxia-inducible factors in hepatocellular carcinoma-transplanted nude mice

Objective The objective of this study was to investigate the inhibitory effects of sorafenib and regorafenib on the growth of hepatocellular carcinoma(HCC)using a subcutaneous transplantation tumor model in nude mice and exploring the effects of sorafenib and regorafenib on the expression of hypoxia-inducible factor(HIF)-1α,HIF-2α,and HIF-1βin HCC tissues collected from HCC-transplanted nude mice.Methods HepG2 cells were inoculated intradermally into nude mice.The mice were randomly assigned to either sorafenib treatment(100 mg/kg),regorafenib treatment(20 mg/kg),or solvent control group(dimethylsulfoxide)(n=8 per group)and received once-daily treatment for 14 days.The tumor volumes were recorded every 3 days after the initiation of treatment.The expression levels of HIF-1α,HIF-1β,HIF-2α,and SART1 in the HCC tissues were examined via quantitative real-time PCR(qRT-PCR)analysis and Western blotting.Results The tumors in the sorafenib and regorafenib treatment groups grew slower and smaller than did the tumors in the solvent control group.qPCR analysis and western blotting demonstrated that the mRNA and protein expressions of HIF-1αand HIF-1βwere down-regulated.The expression of HIF-2αand SART1 was up-regulated in the sorafenib treatment group(P<0.05);meanwhile,the expression of HIF-1αand HIF-1βwas up-regulated,and that of HIF-2αand SART1 was down-regulated in the regorafenib treatment group(P<0.05).Conclusion The expression of hypoxia-associated factor is up-regulated by sorafenib and down-regulated by regorafenib,which may induce the different effects of sorafenib on the expression of HIFs.

Circular Polarization Hologram Realized by Pancharatnam-Berry Phase in Microwave Frequency

Metasurfaces have shown great potential in controlling the propagation of electromagnetic waves, making them suitable for holographic beam-shaping elements. Using the principle of array synthesis, holograms have been realized in microwave frequency to manipulate electromagnetic waves to generate specific field patterns. However, current research is almost based on linear polarization and has little analysis on the circular polarization microwave hologram. Herein, we propose a circular polarization hologram realized by sub-wavelength units with self-adaptively phase profiles of electromagnetic waves. The full, continuous control of the phase is achieved by using a single structure unit based on the Pancharatnam-Berry phase. The inhomogeneity of wave-front is considered through amplitude and phase compensation which are essential to improve the quality of microwave hologram. The model achieves circular polarization hologram in microwave frequency and the clear field pattern is generated. The circular polarization hologram enriched the research field of microwave imaging, thus providing more inspirations for the development of various related techniques.

超乳联合房角镜下房角分离术治疗急性闭角型青光眼合并白内障

目的:观察急性闭角型青光眼合并年龄相关性白内障患者给予超声乳化人工晶状体(IOL)植入联合术中房角镜直视下钝性房角分离术后视力、眼压、房角参数、房角宽度的变化。方法:前瞻性研究。选取2019-08/2021-02就诊于我院眼科,诊断为急性闭角型青光眼(APACG)合并年龄相关性白内障患者共80眼。所有患者行白内障超声乳化摘除IOL植入联合术中房角镜直视下房角钝性分离术。观察术前及术后1wk,1、3、6mo最佳矫正视力、眼压、中央前房深度(ACD)、房角开放距离(AOD500)、小梁虹膜夹角(TIA),并同期行房角镜检查评估房角开放情况,对所得测量值进行统计学分析。结果:患者术后1wk,1、3、6mo视力与术前相比均提高(P<0.05),术后各时间点间视力无差异(P>0.05)。术后1wk,1、3、6mo眼压均较术前下降(P<0.05),术后各时期眼压无差异(P>0.05)。术后1wk,1、3、6mo ACD均较术前有所加深(P<0.05),术后各时期ACD比较无差异(P>0.05)。术后1wk,1、3、6mo TIA均较术前增宽(P<0.05)。术后各时期TIA比较无差异(P>0.05)。术后1wk,1、3、6mo AOD500均较术前有所增加(P<0.05),术后各时期AOD500比较无差异(P>0.05)。患者术前上象限、鼻侧象限、下象限及颞侧象限房角宽度与术后1wk,1、3、6mo时相比,宽角眼数明显高于术前,房角宽度构成与术前相比有差异(P<0.05)。结论:超声乳化白内障摘除IOL植入联合术中钝性房角分离术治疗急性闭角型青光眼合并年龄相关性白内障,可显著提高视力,降低眼压,增加中央前房深度,开放房角,且术后效果稳定,是一种有效的手术方法。

枸杞多糖对LPS诱导的人视网膜色素上皮细胞炎性反应的影响及机制

目的:探索枸杞多糖(LBP)对细菌脂多糖(LPS)诱导的人视网膜色素上皮(ARPE-19)细胞的炎性反应的影响及其可能介导的信号通路。方法:通过LPS刺激体外培养的ARPE-19细胞构建炎性反应模型。将细胞随机分为5组,空白组使用完全培养基培养,LPS组给予含10μg/mL LPS的完全培养基刺激24h,低、中、高浓度LBP组分别给予0.1、0.5、1mg/mL LBP完全培养基孵育24h后给予含10μg/mL LPS的完全培养基刺激24h。应用CCK-8观察细胞存活率、实时荧光定量PCR检测相关炎性因子的mRNA表达量及Western-blot检测NF-κB/MAPK信号通路相关磷酸化蛋白表达量的变化。结果:与正常细胞相比,LPS刺激后,ARPE-19的存活率下降。同时,随着外源性LBP浓度增加,ARPE-19的细胞存活率升高,且细胞内炎性因子IL-1β、IL-6和MCP-1的表达量降低,并伴随NF-κB/MAPK通路的相关磷酸化蛋白(p-p65、p-IκBα、p-JNK、p-ERK及p-p38)的表达下降。结论:枸杞多糖通过抑制胞内炎性因子及NF-κB/MAPK通路相关因子的磷酸化,从而阻止LPS诱导人视网膜色素上皮细胞产生的炎性反应。

中国电力产业组织结构分析及优化建议

我国电力产业自形成至今已取得了非常大的进展,但由于电力行业特有的属性和国家行政的垄断,导致目前电力市场向竞争市场的发展过程步伐缓慢。虽然有三次明显的改革,但改革后的市场结构、企业行为和市场绩效还是存在种种问题,因此文中运用哈佛学派的贝恩的SCP分析理论框架对我国电力产业发电侧市场结构、市场行为和市场绩效及三者的关系进行分析,旨在描述电力产业组织现状,发现问题并为下步电力市场改革、电力产业组织进一步优化提供建议。研究发现:一、我国电力行业中五大电力集团的市场集中不断在扩大,外资及民营企业市场份额有缩小的趋势;二、电力产业规制制度不健全和行政干预是电力市场进一步优化的最大障碍;三、位居高耗能的火电机组占比例过大,需要进行电源优化,有效降低能耗,资源配资更加有效。

Are parental rearing patterns and learning burnout correlated with empathy amongst undergraduate nursing students?

Objective:Empathy can help establish harmonious nurse-patient relationships.We aimed to assess the status of empathy,and explore the relationship between learning burnout,parental rearing patterns and empathy amongst nursing students.Method:A questionnaire survey that employed the Learning Burnout Scale,the Short-Form Egna Minnenav Barndoms Uppfostran(s-EMBU)and the Jefferson Scale of Empathy was conducted amongst 562 nursing students.The data were analysed on the basis of descriptive statistic and correlation analysis was used.Results:Empathy is negatively correlated with learning burnout,parental rejection and overprotection and showed no positive correlation with parental emotional warmth.Conclusions:Educators should pay attention to nursing students'feelings and learning burnout status and take positive measures to improve the empathy level of the students.Positive parental rearing patterns also help cultivate empathy.

Effects of osmotic stress on the expression profiling of aquaporin genes in the roughskin sculpin(Trachidermus fasciatus)

Aquaporins(AQPs)are a family of integral membrane proteins that have been shown to be important for osmoregulation in many vertebrates.To identify potential stress resistance-related aqp genes in salinity adaptation of the roughskin sculpin Trachidermus fasciatus,we investigated the time-course expression dynamics of seven aquaporin genes(aqp1,4,7,8,10,11 and 12)in three osmoregulatory tissues(kidney,gill and intestine)and one metabolic tissue(liver).The fish were subjected to two different acute osmotic treatments(seawater-tofreshwater transfer respectively achieved in 1 h and 24 h,namely,E-acute and acute group).The expression profiling of the seven aqp genes were performed using quantitative real-time PCR(qRT-PCR).At the time of all sampling time points(0 h,12 h,24 h and 48 h),no expression of aqp4 was found in the gill,liver and intestine;no expression of aqp7 was found in the gill and liver.Significant differences of aqp expression were determined in the four target tissues,and the mRNA levels were largely variable among gene members and tissues.Similar patterns of the time-course expression were detected in most of the aqp genes in T.fasciatus between the two acute groups,except that only one gene(aqp12)in the kidney and three genes(aqp7,aqp8 and aqp10)in the intestine revealed different expression patterns.These results suggest that the expression response of aqp genes was similar under osmotic changes with different rates.

Effect of Dy addition on microstructure and mechanical properties of Mg-4Y-3Nd-0.4Zr alloy

Minor Dy element was added into a Mg?4Y?3Nd?0.4Zr alloy,and its effects on the microstructure and the mechanicalproperties at elevated temperatures were investigated.Scanning electron microscope(SEM)and transmission electron microscope(TEM)were used to observe the microstructures.The results indicated that the as-cast eutectic and isolated cuboid-shaped Mg?REphases were Mg5RE and Mg3RE17,respectively,and distributed mainly along grain boundaries.After a solution treatment,theeutectic Mg5RE phases were dissolved into the matrix,whereas the Mg3RE17compound still remained.After peak aging,fineMg?RE phases were precipitated homogeneously within the matrix of the alloys containing Dy.Dy addition can result in asignificant improvement in the tensile strength at both room and elevated temperatures,and a slight decrease in the elongation.

Analysis of black water aggregation in Taihu Lake

Black water aggregation （BWA） in Taihu Lake is a disaster for the lake environment. It is a phenomenon resulting from water environmental deterioration and eutrophication caused by accumulation of pollutants in the lake, according to research on the water quality, pollutants of BWA, and occurrence mechanisms of BWA. Dead algae are the material base of BWA, the polluted sediment is an important factor for the formation of BWA, and hydrological and meteorological conditions such as sun light, air temperature, wind speed, and water flow are the other factors that may lead to the formation of BWA. Thioether substances such as dimethyl trisulfide are the representative pollutants of BWA. Parameters such as chlorophyll-a, DO, pH, and water temperature are sensitive indicators of BWA. Measures such as algae collection, ecological dredging, pollution control, and water diversion from the Yangtze River to the lake, are effective, and strengthening aeration is an emergency measure to control BWA.

Fixed-Time Lyapunov Criteria and State-Feedback Controller Design for Stochastic Nonlinear Systems

This paper investigates the fixed-time stability theorem and state-feedback controller design for stochastic nonlinear systems.We propose an improved fixed-time Lyapunov theorem with a more rigorous and reasonable proof procedure.In particular,an important corollary is obtained,which can give a less conservative upper-bound estimate of the settling time.Based on the backstepping technique and the addition of a power integrator method,a state-feedback controller is skillfully designed for a class of stochastic nonlinear systems.It is proved that the proposed controller can render the closed-loop system fixed-time stable in probability with the help of the proposed fixed-time stability criteria.Finally,the effectiveness of the proposed controller is demonstrated by simulation examples and comparisons.

How to Improve the Teaching Quality of Plant Physiology?

Plant Physiology is a compulsory specialized fundamental course,and plays an important role in the whole education of plant-related majors in agricultural institutions. In order to improve the educational effects and train specialized students in agriculture,the methods in Plant Physiology teaching in Qingdao Agricultural University are summarized in this paper. The results will provide a reference for improving the teaching of Plant Physiology in the future.

昭通大山包观鸟旅游现状分析及对策

随着大山包旅的发展,大山包的经济得到迅速的提高,但是大山包也面临着一些生态环境问题。本文通过对大山包的自然资源的分析,并根据大山包发展观鸟旅游所面临的问题,对大山包观鸟旅游的发展提出了一些建议和对策。

Genome-wide investigation of defensin genes in peanut(Arachis hypogaea L.)reveals AhDef2.2 conferring resistance to bacterial wilt

Peanut(Arachis hypogea L.)bacterial wilt(BW)is a devastating disease caused by Ralstonia solanacearum that results in severe yield and quality losses.Plant defensins are short cysteine-rich peptides with antimicrobial activity.The role of defensin genes(Ah Def)in peanut is unclear.A genome-wide investigation of Ah Def genes was undertaken,and 12 identified Ah Def genes were classified into two groups containing the gamma-thionin domain formed by four disulfide pairs:Cys1-Cys8,Cys2-Cys5,Cys3-Cys6,and Cys4-Cys7.In silico analysis revealed that Ah Def genes showed highly conserved architectural features and contained cis-elements associated with phytohormone signaling and defense responses.A highly resistant cultivar,H108(R)and a susceptible accession,H107(S)were tested by R.solanacearum inoculation.H108(R)showed fewer symptoms than H107(S)owing to inhibition of bacterial reproduction and spread in the vascular bundles of roots and stems.In a transcriptomic expression profile,Ah Def genes,particularly Ah Def1.6 and Ah Def2.2,were up-regulated in H108(R)compared with H107(S)under R.solanacearum infection and phytohormone treatment.Subcellular localization showed that the Ah Def1.6 and Ah Def2.2 proteins were both expressed specifically on the plasma membrane.Overexpression of protein fusion Ah Def2.2-YFP in Nicotiana benthamiana and peanut leaves increased resistance to R.solanacearum,suggesting its role in response to BW infection.Ah Def2.2 may be valuable for peanut resistance breeding.