静止坐标系下无电网电压传感器虚拟同步机控制策略

针对采用虚拟磁链算法的无电网电压传感器存在的直流偏移等问题,提出基于一阶低通滤波器和高通滤波器串联结构的改进磁链观测器,利用改进的磁链观测器得出虚拟磁链,提高了观测的精度。在得到虚拟磁链的基础上,针对不同电网频率运行条件,利用锁相环思想提出电网角频率的计算结构,并由虚拟出的磁链与电压的关系来重构电网电压。此外,将所提无电网电压传感器策略应用于网侧变流器系统中,在两相静止坐标系下设计虚拟同步控制结构,相比于旋转坐标系,可省去控制内环的解耦环节,同时还能简化坐标变换环节,避免了因坐标变换中角度不准而引入的不稳定因素。最后,通过仿真与实验验证所提控制策略与磁链观测器的有效性与可靠性。

Cardiovascular risk burden,dementia risk and brain structural imaging markers:a study from UK Biobank

Background Cardiovascular risk burden is associated with dementia risk and neurodegeneration-related brain structure,while the role of genetics and incident cardiovascular disease(CVD)remains unclear.Aims To examine the association of overall cardiovascular risk burden with the risk of major dementia subtypes and volumes of related brain regions in a large sample,and to explore the role of genetics and CVD onset.Methods A prospective study among 354 654 participants free of CVD and dementia(2006-2010,mean age 56.4 years)was conducted within the UK Biobank,with brain magnetic resonance imaging(MRl)measurement availablefor 15104participants since 2014.CVD risk burden was evaluated by the Framingham General Cardiovascular Risk Score(FGCRS).Dementia diagnosis was ascertained from inpatient and death register data.Results Overamedian 12.0-yearfollow-up,3998 all-cause dementia cases were identified.Higher FGCRS was associated with increasedall-cause dementia risk after adjusting for demographic,major lifestyle,clinical factors and the polygenic risk score(PRS)of Alzheimer's disease.Comparing the high versus low tertile of FGCRS,the odds ratios(ORs)and 95%confidence intervals(Cls)were 1.26(1.12 to 1.41)for all-cause dementia,1.67(1.33 to 2.09)for Alzheimer's disease and 1.53(1.07 to 2.16)for vascular dementia(all p_(treng)<0.05).Incident stroke and coronary heart disease accounted for 14%(95%Cl:9% to 21%)of the association between FGCRS and all-cause dementia.Interactions were not detected for FGCRS and PRS on the risk of any dementia subtype.We observed an 83%(95%Cl:47%to 128%)higher all-cause dementia risk comparing the high-high versus low-low FGCRS-PRS category.For brain volumes,higher FGCRS was associated with greater log-transformed white matter hyperintensities,smaller cortical volume and smaller grey matter volume.Conclusions Our findings suggest that the positive association of cardiovascular risk burden with dementia risk also applies to major dementia subtypes.The association of cardiovascular risk burden with all-cause dementia is largely independent of CVD onset and genetic predisposition to dementia.

Settlement Control Standards of Construction and Expansion for Mountainous Highway Roadbeds

This article analyzes the differential settlement of new and old roadbeds after widening and its characteristics based on a highway reconstruction and expansion project case study.The research proposes a subgrade settlement control standard that states that the maximum differential settlement value should be less than 5 cm when the embankment fill height exceeds 20 m.Similarly,the maximum differential settlement value should be less than 10 cm when the embankment fill height does not exceed 20 m.The findings of the study can provide a useful reference for the design of roadbed widening in highway reconstruction and expansion projects.

Analysis of Roadbed Pavement Designs for Highway Reconstruction and Upgrading

This paper focuses on the route and roadbed pavement design in highway reconstruction and upgrading projects.It discusses the importance of project design for highway reconstruction and upgrading,highlighting key aspects of route design and roadbed pavement design.The analysis reveals that the main design considerations in these projects include controlling factors of route reconstruction,expansion,and upgrading,as well as route plan design and longitudinal section design combined with roadbed pavement.In roadbed pavement design,it is crucial for designers to thoroughly collect existing data and make reasonable use of the current roadbed and pavement to develop a comprehensive design scheme.This analysis aims to provide a reference for the reasonable design of such projects.

Design Method for Road Reconstruction and Expansion

This article analyzes the method for designing routes in road reconstruction and expansion projects,using an actual engineering project as an example.This includes an overview of a specific road reconstruction and expansion project,an analysis of the preexisting road,the basic principles of the design road project,and an analysis of the design methods and steps.This study aims to offer some guidance for road reconstruction and expansion design.

无控飞行弹箭气动加热特性

针对无控飞行弹箭动态红外特征的数值计算问题,提出了一种计算其表面气动加热的数值方法。建立了155mm口径无控炮弹的六自由度刚体弹道仿真模型;取目标在亚声速、跨声速、超声速飞行状态下的弹道数据为来流条件,基于FLUENT进行了外流场数值模拟;分析了弹体表面压力、温度分布及驻点热流密度的变化规律,并与经验公式的计算结果进行了对比验证。结果表明,随着弹头曲率半径减小,驻点热流密度呈非线性增加趋势,马赫数越高,弹体表面的峰值压力和温度越高,且温度变化梯度越大;高温区集中于弹头及弹头部与圆柱部交接处,低温区分布在弹体尾部和底部,数值模拟与经验公式的计算值吻合较好。

胃空肠储袋侧-端吻合术(附66例报告)

目的:介绍一种胃空肠吻合的新术式——胃空肠储袋侧-端吻合术。方法:在传统Billroth II式胃空肠吻合术基础上,成都军区总医院胃肠外科设计了在输入袢与输出袢交汇处增加空肠侧-侧吻合形成空肠储袋,其顶端与胃后壁吻合的新术式——胃空肠储袋侧-端吻合术。本文回顾性分析自2012年3月至2014年2月实施66例胃空肠储袋侧-端吻合术患者的临床资料。其中,51例实施手辅助腹腔镜远端胃癌D2根治术,8例不能切除胃癌行上腹部正中小探查切口、胃空肠储袋侧-端吻合术+小弯侧血管神经结扎切断术,7例良性幽门梗阻行手辅助腹腔镜高选择性迷走神经切断+远端半胃切除术。结果:手术切口6.5~8 cm(平均7.1 cm),手术时间70~205 min(平均165.6 min),术中出血量50~300 ml(平均174.5 ml),肛门排气时间2~5天(平均3.7天),术后饮食恢复时间3~7天(平均4.6天),术后住院时间6~13天(8.3天)。术后2 h腹腔血管出血1例,再手术止血治愈。无胃瘫,无围手术期死亡。随访1~12个月,患者自述无反酸和反流性食管炎症状出现,胃镜复查见轻度吻合口炎3例,胃内胆汁返流明显者2例。结论:胃空肠储袋侧-端吻合术,操作简单,手术安全,且预防反流性胃炎的临床效果良好;空肠储袋具有贮存和收集胆汁等消化液的功能,有利于患者术后早期恢复。

聚酯玻纤布沥青卷材的制备和性能研究

介绍了聚酯玻纤布复配及其沥青卷材的制备,从抗水抗冻融、抗老化、层间粘结和永久变形等方面对聚酯玻纤布沥青卷材和SBS改性沥青防水卷材的性能进行对比分析。结果表明,基质沥青用粘层油在1.0 kg/m2时效果最好;聚酯玻纤布沥青卷材具有更好的高温水稳定性、抗老化性和抗永久变形能力。

Clinical-radiomics nomogram for predicting esophagogastric variceal bleeding risk noninvasively in patients with cirrhosis

BACKGROUND Esophagogastric variceal bleeding(EGVB)is a serious complication of patients with decompensated cirrhosis and is associated with high mortality and morbidity.Early diagnosis and screening of cirrhotic patients at risk for EGVB is crucial.Currently,there is a lack of noninvasive predictive models widely available in clinical practice.AIM To develop a nomogram based on clinical variables and radiomics to facilitate the noninvasive prediction of EGVB in cirrhotic patients.METHODS A total of 211 cirrhotic patients hospitalized between September 2017 and December 2021 were included in this retrospective study.Patients were divided into training(n=149)and validation(n=62)groups at a 7:3 ratio.Participants underwent three-phase computed tomography(CT)scans before endoscopy,and radiomic features were extracted from portal venous phase CT images.The independent sample t-test and least absolute shrinkage and selection operator logistic regression were used to screen out the best features and establish a radiomics signature(RadScore).Univariate and multivariate analyses were performed to determine the independent predictors of EGVB in clinical settings.A noninvasive predictive nomogram for the risk of EGVB was built using independent clinical predictors and RadScore.Receiver operating characteristic,calibration,clinical decision,and clinical impact curves were applied to evaluate the model’s performance.RESULTS Albumin(P=0.001),fibrinogen(P=0.001),portal vein thrombosis(P=0.002),aspartate aminotransferase(P=0.001),and spleen thickness(P=0.025)were selected as independent clinical predictors of EGVB.RadScore,constructed with five CT features of the liver region and three of the spleen regions,performed well in training(area under the receiver operating characteristic curve(AUC)=0.817)as well as in validation(AUC=0.741)cohorts.There was excellent predictive performance in both the training and validation cohorts for the clinical-radiomics model(AUC=0.925 and 0.912,respectively).Compared with the existing noninvasive models such as ratio of aspartate aminotransferase to platelets and Fibrosis-4 scores,our combined model had better predictive accuracy with the Delong's test less than 0.05.The Nomogram had a good fit in the calibration curve(P>0.05),and the clinical decision curve further supported its clinical utility.CONCLUSION We designed and validated a clinical-radiomics nomogram able to noninvasively predict whether cirrhotic patients will develop EGVB,thus facilitating early diagnosis and treatment.

Intermittent tri-weekly docetaxel plus bicalutamide in patients with castration-resistant prostate cancer： a single-arm prospective study using a historical control for comparison

Whether continuous docetaxel （DTX） chemotherapy offers an advantage over intermittent therapy for castration-resistant prostate cancer （CRPC） is unknown. In this study, we evaluated the efficacy, toxicity and quality of life （QoL） of intermittent tri-weekly DTX with bicalutamide in CRPC. Forty-two patients （group A） with CRPC were enrolled. The patients received intravenous DTX （75 mg m^-2） once tri-weekly with oral bicalutamide （50 mg） once daily. Patients had a DTX holiday when the prostate-specific antigen （PSA） level declined ≥ 50%. DTX was restarted in patients with a PSA increase ≥ 25%. Sixty patients （group B） who had matching characteristics and had continuously received DTX without bicalutamide for 10-12 cycles were also enrolled. There were no statistically significant differences in progression-free survival （8 months vs. 9 months, P=0.866） or overall survival （19 months vs. 21 months, P=0.753） between groups A and B; however, the proportions of patients in group A with all grades of neutropenia （33% vs. 58%, P=0.013） and nausea/vomiting （11% vs. 29%, P=0.024） were significantly less compared to group B. A significant improvement in the global health and fatigue scores was recorded for group A post-chemotherapy compared to pre-chemotherapy （P〈0.05）. The fatigue, nausea/ vomiting and appetite loss scores in group B were increased post-chemotherapy compared to pre-chemotherapy （P〈0.05）. In conclusion, intermittent tri-weekly DTX plus bicalutamide is well tolerated and has the potential to achieve comparable disease control with an improvement in QoL for oatients with CRPC.

PEPT1-mediated prodrug strategy for oral delivery of peramivir

Peramivir was a novel and highly potent neuraminidase(NA) inhibitor for the treatment of influenza A and B. However, it exhibited a very low oral bioavailability(only 3%) due to the high polarity(log P of-1.4) and the low membrane permeability across the intestine. To utilize the PEPT1-mediated prodrug strategy to improve the oral absorption and develop the oral alternative, seven amino acid ester prodrugs and seven amino acid amide prodrugs have been synthesized. The permeability of these prodrugs across Caco-2 cells were screened. Peramivr-(CH_2)_2-l-Val and Peramivir-l-Ile were of the highest permeability in ester prodrugs and amide prodrugs, respectively, and then they were selected for further studies. Glycylsarcosine(gly-sar) uptake by Caco-2 could be inbihited by Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile in a concentration-dependent manner, and the IC 50 was 1.34 ± 0.31 m M and 1.78 ± 0.48 m M, respectively. The direct uptake of Peramivir-(CH_2)_2-l-Val and Peramivirl-Ile in MDCK-PEPT1 cells were significantly higher than in MDCK mock cells, and could be markedly inhibited by gly-sar. The uptake of Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile(0.01 to 50 m M) in MDCK-hPEPT1 cells conformed to Michaelis–Menten Equation. The oral bioavailability of peramivir was 65.3% and 37.3% after the oral administration of Peramivir-(CH_2)_2-l-Val and Peramivir-l-Ile to rats, respectively. The oral absorption and bioactivation of Peramivir-(CH_2)_2-l-Val was rapid and extensive, and no Peramivir-(CH_2)_2-l-Val was found in plasma. Because the amide bond was relatively stable, Peramivir-l-Ile could not be totally converted to the parent drug in vivo. Peramivir-(CH_2)_2-l-Val with good oral profiles and rapid bioactivation might be a promising prodrug for the further clinic development. The present study also corroborated the idea that the PEPT1-mediated prodrug approach has enormous promise for improving the oral absorption of poorly absorbed drug.

Orientation and Motion of Water Molecules at Air/Water Interface

Here we report a quantitative study of the orientational structure and motion of water molecule at the air/water interface. Analysis of Sum Frequency Generation （SFG） vibrational peak of the free O-H stretching band at 3700 cm^-1 in four experimental configurations showed that orientational motion of water molecule at air/water interface is libratory within a limited angular range. The free OH bond of the interracial water molecule is tilted around 33°from the interface normal and the orientational distribution or motion width is less than 15°. This picture is significantly different from the previous conclusion that the interracial water molecule orientation varies over a broad range within the ultrafast vibrational relaxation time, the only direct experimental study concluded for ultrafast and broad orient, ational motion of a liquid interface by Wei et al. （Phys. Rev. Lett. 86, 4799, （2001）） using single SFG experimental configuration.

Development and evaluation of a predictive nomogram for survival in heat stroke patients: a retrospective cohort study

BACKGROUND:This study aimed to establish an eff ective nomogram to predict the survival of heat stroke(HS)based on risk factors.METHODS:This was a retrospective,observational multicenter cohort study.We analyzed patients diagnosed with HS,who were treated between May 1 and September 30,2018 at 15 tertiary hospitals from 11 cities in Northern China.RESULTS:Among the 175 patients,32 patients(18.29%)died before hospital discharge.After the univariate analysis,mechanical ventilation,initial mean arterial pressure<70 mmHg,maximum heart rate,lab results on day 1(white blood cell count,alanine aminotransferase,creatinine),and Glasgow admission prediction score were included in multivariate analysis.Multivariate Cox regression showed that invasive ventilation,initial mean arterial pressure<70 mmHg(1 mmHg=0.133 kPa),and Glasgow admission prediction score were independent risk factors for HS.The nomogram was established for predicting 7-d and 14-d survival in the training cohort.The nomogram exhibited a concordance index(C-index)of 0.880(95%confidence interval[95%CI]0.831-0.930)by bootstrapping validation(B=1,000).Furthermore,the nomogram performed better when predicting 14-d survival,compared to 7-d survival.The prognostic index cut-off value was set at 2.085,according to the operating characteristic curve for overall survival prediction.The model showed good calibration ability in the internal and external validation datasets.CONCLUSION:A novel nomogram,integrated with prognostic factors,was proposed;it was highly predictive of the survival in HS patients.

三全育人背景下的多维度大学化学实验课程思政建设

针对大学化学实验课程的特点,从课程教学目标设计、实验教学活动设计和课程教学成果评价三个方面,探索教学过程中专业知识与思政元素的结合点。分别从培养学生的爱国情怀、科学素养、创新意识、职业素养、社会责任感、辩证思维和绿色发展理念等多个维度介绍在大学化学实验教学过程中实施思政教育的具体措施。利用好课堂教学的主渠道,将知识探究、能力建设和价值塑造三者融为一体,推进全员全程全方位育人的重要实践,培养学生成为德智体美劳全面发展的新时代社会主义建设者和接班人。

Comparison of hand-assisted laparoscopic radical gastrectomy and laparoscopic-assisted radical gastrectomy:A systematic review and meta-analysis

BACKGROUND Gastrectomy is the optimal treatment for gastric cancer.Laparoscopic-assisted gastrectomy(LAG)has been extensively employed,while hand-assisted laparoscopic gastrectomy(HALG),which is similar to LAG,remains controversial.Although HALG is popular in China,some surgeons do not accept it as a minimal-access technique.AIM To assess the safety and practicability of HALG by comparing the short-term outcomes of HALG and LAG.METHODS The electronic databases of EMBASE,PubMed,China National Knowledge Infrastructure,and Cochrane Library were thoroughly searched,and randomized controlled trials(RCTs)comparing HALG and LAG were included.The study results,including surgery time,blood loss,retrieved lymphatic nodes,incision length,time to first flatus,hospitalization duration,and all postsurgical complications,were compared between the two groups.RESULTS Five RCTs,which included 302 cases with HALG and 298 cases with LAG,were considered eligible for inclusion.Meta-analysis showed that HALG significantly reduced surgery time(P<0.01),hospital duration(P<0.01),and overall postsurgical complications(P<0.01).Additionally,HALG significantly increased the number of retrieved lymphatic nodes(P=0.01)and incision length(P<0.01)compared with LAG.The blood loss and time to first flatus were similar between the two groups(P>0.05).CONCLUSION Compared with LAG,HALG is a simpler and safer technique.Additionally,HALG should be used as a minimal-access technique,especially in technologically undeveloped areas.

Order-Disorder Transition of Carboxyl Terminated Chains in Polydiacetylenes Vesicles Probed by Second Harmonic Generation and Two-Photon Fluorescence

To understand and control the interfacial properties of polydiacetylenes(PDAs)vesicles withπ-conjugated backbone is very important for their colorimetric sensing of chemical and biological targets.In this work,we adopted 10,12-pentacosadiynoic acid(PCDA)as the model molecule to prepare PDAs vesicles in aqueous solution with different forms(from monomer to blue-to-purple-to-red phase)by controlling the UV irradiation dose.The variations of the interfacial conformation of PDAs vesicles during chromatic transitions were inspected by the adsorption behaviors of probe molecules(4-(4-diethylaminostyry)-1-methylpyridinium iodide,D289)on vesicle surface with surface-specific second harmonic generation(SHG)and zeta potential measurements.Resonant SHG signal from D289 adsorbed on vesicle surface attenuated sharply,and the adsorption free energy as well as the corresponding two-photon fluorescence signal decreased slightly in chromatic transitions.While,the change in the surface density of the adsorbed D289 molecules for PDAs vesicles with different forms was relatively small as estimated from zeta potential measurements.The attenuation of the SHG intensity was thus attributed to the overall order-disorder transition and the changed orientation of D289 molecules caused by the gradual distortion of carboxyl head group driven by backbone perturbation.

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

The orientation angle is an important parameter that reflects the structure of molecules at interfaces. In order to obtain this parameter, second order nonlinear spectroscopic techniques including second harmonic generation （SHG） and sum frequency generation-vibrational spec- troscopy （SFG-VS） have been successfully applied through analysis of the nonlinear signal from various polarizations. In some SHG and SFG-VS experiments, total internal reflection （TIR） configuration has been adopted to get enhanced signals. However, the reports on the detailed procedure of the polarization analysis and the calculation of the orientation angle of interracial molecules under TIR configuration are still very few. In this paper, we mea- sured the orientation angles of two molecules at the hexadecane-water interface under TIR and Non-TIR experimental configurations. The results measured from polarization analysis in TIR configuration consist with those obtained from Non-TIR configuration. This work demonstrates the feasibility and accuracy of polarization analysis in the determination of the orientation angle of molecules at the interfaces under TIR-SHG configuration.

Hydroxyl Group Modifies Aggregation Behavior of a Non-ionic Hydro-fluorocarbon Hybrid Surfactant by Disrupting Interfacial Water

Two non-ionic hydro-fluorocarbon hybrid surfactants with and without hydroxyl groups were synthesized and compared.They exhibited good thermal stability and superior surface activity.It was observed that the hydroxyl group had a profound effect on modifying the surface tension of their solutions and the morphology of the formed micelles.This effect may be attributed to the rearranging of the alkane group from above the air/aqueous surface to below it and the disrupting of the interfacial water structure induced by the hydroxyl groups.This work provides a strategy to weaken the immiscibility between hydrocarbon and fluorocarbon chains by modifying their orientational structure at the interface,thus it is helpful for the design of surfactants with varied interfacial properties.

Maximal-minimal correlation atoms algorithm for sparse recovery

A new iterative algorithm is proposed to reconstruct an unknown sparse signal from a set of projected measurements. Unlike existing greedy pursuit methods which only consider the atoms having the highest correlation with the residual signal, the proposed algorithm not only considers the higher correlation atoms but also reserves the lower correlation atoms with the residual signal. In the lower correlation atoms, only a few are correct which usually impact the reconstructive performance and decide the reconstruction dynamic range of greedy pursuit methods. The others are redundant. In order to avoid redundant atoms impacting the reconstructive accuracy, the Bayesian pursuit algorithm is used to eliminate them. Simulation results show that the proposed algorithm can improve the reconstructive dynamic range and the reconstructive accuracy. Furthermore, better noise immunity compared with the existing greedy pursuit methods can be obtained.

Quantitative Interpretation of Polarization SFG Vibrational Spectra of Air/Methanol Interface

Even though in IR and Raman spectra of liquid methanol there is always an apparent feature for the asymmetric stretching mode of the CH3 group around 2970 cm^-1, this feature has not been observed in the Sum Frequency Generation Vibrational Spectroscopy （SFG-VS） in any polarizations from the air/methanol interface. Here we present a treatment based on a corrected bond additivity model to quantitatively interpret the SFG-VS of the air/methanol interface from the IR and Raman spectra of liquid methanol.