城市轨道交通参数可调覆盖式轨道吸尘装置研究

[目的]针对城市轨道交通钢轨打磨后产生的铁屑粉尘难以清除的问题,需结合铁屑粉尘的特性,设计一套能够进行参数调整的覆盖式轨道吸尘装置。[方法]通过分析钢轨打磨铁屑的特性与道床结构,确定轨道吸尘装置设计的可行性与必要性;对该吸尘装置的吸口进行设计,采用流体仿真分析吸口宽度和离地间隙对吸尘系统风压、风量及功率的影响,并对比不同参数下的风量与风压;根据灰尘的运动模型和有效沉降因素对集尘箱结构进行优化,提高其集尘效果,并通过流体仿真验证其有效性;根据设计参数建立轨道吸尘小模型装置,并通过不同尺寸试验物料、不同离地间隙进行对比试验。[结果及结论]吸口宽度的变化对吸尘系统的影响不大,在其小范围变化的情况下可以忽略;吸口离地间隙越大,吸尘系统中的风压逐渐减小,风量逐渐变大,功率也逐渐变大,吸尘率也随之下降;试验装置吸口离地间隙小于20 mm时,对钢轨打磨铁屑的吸除率达到90%以上,对粒径5 mm的砂石的吸除率达到92%以上,对粒径1 mm的沙尘的吸除率达到96%以上。设计的参数可调式轨道吸尘装置具有较好的吸尘效果。

3个大珠母贝养殖群体生物学特征及肌肉营养成分分析

【目的】探究不同大珠母贝(Pinctada maxima)养殖群体外部形态特征和肌肉营养成分的差异,为不同地理大珠母贝种质资源的分类管理与合理利用提供科学依据,也为野生大珠母贝种质资源的管理与保护提供理论参考。【方法】采集广西北海、海南三亚和广东徐闻等地的大珠母贝养殖群体,测量其体质量、壳长、壳宽、壳高及铰合线长,检测大珠母贝肌肉营养成分,并根据联合国粮农组织和世界卫生组织(FAO/WHO)建议的氨基酸评分标准模式进行品质评价。【结果】北海(BH)群体的壳长、壳宽、壳高和铰合线长均高于三亚(SY)群体和徐闻(XW)群体;SY群体除了体质量和壳宽外,其他形态性状均显著低于BH群体和XW群体(P<0.05,下同)。除了BH群体与XW群体间的壳宽性状差异系数(1.50)大于1.28外,其余性状差异系数均小于1.28,说明3个大珠母贝养殖群体间的形态差异尚未达到亚种分化水平。主成分分析和层级聚类分析结果均显示,3个群体的散布并未完全分离,彼此间均有一定程度的重合。XW群体肌肉鲜样的粗蛋白含量显著高于BH群体和SY群体,但粗脂肪含量差异不显著(P>0.05)。3个群体共检出17种氨基酸,且均以天冬氨酸(Asp)、谷氨酸(Glu)、甘氨酸(Gly)和精氨酸(Arg)含量较高,合计占总氨基酸的41.15%~45.56%;SY群体的必需氨基酸指数(EAAI)为73.23%,高于BH群体(64.48%)和XW群体(45.53%)。3个群体共检出9种脂肪酸,SY群体多检测出α-亚麻酸,而BH群体和XW群体多检测出油酸。在3个群体肌肉中未检出n-6系列多不饱和脂肪酸(n-6 PUFA),所检出的n-3系列多不饱和脂肪酸(n-3 PUFA)也只有3种[二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)和α-亚麻酸],且以SY群体的含量最高(0.0443%)。【结论】大珠母贝氨基酸含量丰富且均匀,属于优质蛋白,具有较高的营养价值,且SY群体的综合营养价值优于BH群体和XW群体。

基于贝塞尔曲面拟合的子光斑背景噪声去除方法

受天光背景影响,夏克-哈特曼波前传感器子光斑图像背景光增强,导致子光斑质心位置无法准确提取,使得波前传感器探测精度下降。为提高强天光背景影响下波前传感器探测精度,提出了一种基于贝塞尔曲面拟合的背景噪声去除算法。该算法利用贝塞尔曲面拟合背景噪声,不受拟合基函数约束,实现背景噪声与目标光斑信号的有效分离。仿真和实验结果均表明,所提方法对背景噪声的拟合精度不受目标光斑信号的影响,在保证目标光斑信号完整的前提下,能有效拟合非均匀分布背景噪声,相比传统阈值法、加窗法等,在背信比范围为30至120的强天光背景干扰下,将波前探测精度提升约33%。

Co1.5-玉米秸秆生物炭活化过一硫酸盐高效降解莠去津的研究

为解决莠去津的大量使用而导致的环境污染问题,本研究通过水热、煅烧法成功制备出负载型钴基催化剂复合材料Co1.5-玉米秸秆生物炭并构建了过一硫酸盐高效降解体系。通过透射电子显微镜、X射线衍射光谱和比表面积及孔径表征,获得Co1.5-玉米秸秆生物炭催化剂的结构特征信息。对Co1.5-玉米秸秆生物炭/过一硫酸盐体系降解性能和影响因素研究发现,当Co1.5-玉米秸秆生物炭浓度为0.010 g/L、过一硫酸盐浓度为0.075 g/L时,Co1.5-玉米秸秆生物炭/过一硫酸盐体系30 min对莠去津的降解率达到97.96%。本研究为新型高效、绿色催化剂的研发提供了新的制备方案,并为实际废水的治理提供了科学参考。

Effects of Maillard reaction and its product AGEs on aging and age-related diseases

Maillard reaction(MR)is a non-enzymatic browning reaction commonly seen in food processing,which occurs between reducing sugars and compounds with amino groups.Despite certain advantages based on Maillard reaction products(MRPs)found in some food for health and storage application have appeared,however,the MR occurring in human physiological environment can produce advanced glycation end products(AGEs)by non-enzymatic modification of macromolecules such as proteins,lipids and nucleic acid,which could change the structure and functional activity of the molecules themselves.In this review,we take AGEs as our main object,on the one hand,discuss physiologic aging,that is,age-dependent covalent cross-linking and modification of proteins such as collagen that occur in eyes and skin containing connective tissue.On the other hand,pathological aging associated with autoimmune and inflammatory diseases,neurodegenerative diseases,diabetes and diabetic nephropathy,cardiovascular diseases and bone degenerative diseases have been mainly proposed.Based on the series of adverse effects of accelerated aging and disease pathologies caused by MRPs,the possible harm caused by some MR can be slowed down or inhibited by artificial drug intervention,dietary pattern and lifestyle control.It also stimulates people's curiosity to continue to explore the potential link between the MR and human aging and health,which should be paid more attention to for the development of life sciences.

New insights into the deposition of natural gas hydrate on pipeline surfaces:A molecular dynamics simulation study

Natural gas hydrate(NGH)can cause pipeline blockages during the transportation of oil and gas under high pressures and low temperatures.Reducing hydrate adhesion on pipelines is viewed as an efficient way to prevent NGH blockages.Previous studies suggested the water film can greatly increase hydrate adhesion in gas-dominant system.Herein,by performing the molecular dynamics simulations,we find in water-dominant system,the water film plays different roles in hydrate deposition on Fe and its corrosion surfaces.Specifically,due to the strong affinity of water on Fe surface,the deposited hydrate cannot convert the adsorbed water into hydrate,thus,a water film exists.As water affinities decrease(Fe>Fe_(2)O_(3)>FeO>Fe_(3)O_(4)),adsorbed water would convert to amorphous hydrate on Fe_(2)O_(3)and form the ordered hydrate on FeO and Fe_(3)O_(4)after hydrate deposition.While absorbed water film converts to amorphous or to hydrate,the adhesion strength of hydrate continuously increases(Fe<Fe_(2)O_(3)<FeO<Fe_(3)O_(4)).This is because the detachment of deposited hydrate prefers to occur at soft region of liquid layer,the process of which becomes harder as liquid layer vanishes.As a result,contrary to gas-dominant system,the water film plays the weakening roles on hydrate adhesion in water-dominant system.Overall,our results can help to better understand the hydrate deposition mechanisms on Fe and its corrosion surfaces and suggest hydrate deposition can be adjusted by changing water affinities on pipeline surfaces.

Imaging through scattering layers using a near-infrared low-spatial-coherence fiber random laser

Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objectsfrom disordered speckle patterns,achieving imaging through scattering layers.However,the lighting efficiency and fieldof view of existing speckle-correlated imaging systems are limited.Here,a near-infrared low spatial coherence fiberrandom laser illumination method is proposed to address the above limitations.Through the utilization of random Rayleighscattering within dispersion-shifted fibers to provide feedback,coupled with stimulated Raman scattering for amplification,a near-infrared fiber random laser exhibiting a high spectral density and extremely low spatial coherence is generated.Based on the designed fiber random laser,speckle-correlated imaging through scattering layers is achieved,with highlighting efficiency and a large imaging field of view.This work improves the performance of speckle-correlated imagingand enriches the research on imaging through scattering medium.

Eco-friendly high-throughput screening of cephalosporins impurities: Utilizing 2D-carbon microfiber fractionation system combined with quadrupole time of flight high-resolution mass spectrometer

Owing to its high sensitivity,selectivity,and accuracy,liquid chromatography coupled with mass spectrometry(LC-MS)is commonly employed to screen,confirm,and quantify impurities in drugs[1].However,LC-MS has certain drawbacks such as complicated pretreatment steps,long analysis time,large consumption of organic solvents,high maintenance costs,and,most notably,the need for high-pressure pumps and compatible hardware because of the high column backpressure[2].In this study,a two-dimensional(2D)microscale carbon fiber(CF)/active carbon fiber(ACF)system combined with a quadrupole time-of-flight high-resolution mass spectrometry(2DmCFs-QTOF-HRMS)system was developed to rapid screening impurities in the typical three generations of oral cephalosporins,i.e.,cephalexin tablets(CPXTs),cefuroxime axetil tablets(CFATs),and cefixime tablets(CFXTs)(Fig.S1).The“fuzzy chromatographic separation”sample pretreatment method separates complex samples into high-,medium-,and weak-polar fractions for successive detection of MS,achieving effective reduction of the ion suppression effect in electrospray ionization(ESI)-MS and improving the MS detection sensitivity.Compared to high performance liquid chromatography(HPLC)-MS,this method has distinct advantages such as less organic solvent consumption(1.5 mL),shorter separation and analysis times(5 min),more information on impurities,and high reproducibility.

Natural variation in maize gene ZmSBR1 confers seedling resistance to Fusarium verticillioides

Maize seedling blight caused by Fusarium verticillioides is a widely occurring maize disease,but the genetics and mechanisms of resistance are not well understood.In this study,GWAS performed by MLM and 3VmrMLM identified 40 and 20 QTNs,associated with seedling blight resistance.These methods identified 49 and 36 genes,respectively.Functional verification of candidate gene ZmSBR1 identified by both methods showed that the resistance of a mutant line to seedling blight decreased by 0.37 grade points after inoculation with F.verticillioides,compared with the WT.The length of the stem rot lesion caused by F.verticillioides increased by 86%in mutant seedlings,and the relative length of the adult plant stalk rot increased by 35%in mutant plants compared to the wild type after inoculation with Fusarium graminearum.Transcriptome analysis showed that expression of defense-related genes after inoculation was down-regulated in the mutant compared to the wild type,synthesis of secondary metabolites associated with resistance was reduced,and the immune response triggered by PAMP decreased,resulting in decreased resistance of mutant maize seedlings.Candidate gene association analysis showed that most maize inbred lines carried the susceptible haplotype.A functional PCR marker was developed.The results demonstrated that ZmSBR1 conferred resistance to multiple Fusarium diseases at the seedling and adult growth stages and had important application value in breeding.

Relationship of inflammatory indices with left atrial appendage thrombus or spontaneous echo contrast in patients with atrial fibrillation

BACKGROUND Inflammatory indices derived from complete blood tests have been reported to be associated with poor outcomes in patients with atrial fibrillation(AF).The data about the relationship between inflammatory indices and left atrial appendage thrombus(LAAT)or dense spontaneous echo contrast(SEC)are limited.AIM To explore the value of inflammatory indices for predicting the presence of LAAT or dense SEC in nonvalvular AF patients.METHODS A total of 406 patients with nonvalvular AF who underwent transesophageal echocardiography were included and divided into two groups based on the presence(study group)or absence(control group)of LAAT or dense SEC.Inflammatory indices,including the neutrophil-to-lymphocyte ratio(NLR),platelet–tolymphocyte ratio(PLR),and lymphocyte-to-monocyte ratio(LMR),were calculated from complete blood analysis.The associations of inflammatory indices RESULTS LAAT and dense SEC were detected in 11(2.7%)and 42(10.3%)patients,respectively.The PLR only showed an association with LAAT/dense SEC in the univariate model.Elevated NLR(odds ratio[OR]=1.48,95%confidence interval[CI]:1.11-1.98,P=0.007)and reduced LMR(OR=0.59,95%CI:0.41-0.83,P=0.003)were found to be independent risk factors for the presence of LAAT/dense SEC.The areas under the NLR and LMR curves for predicting LAAT/dense SEC were 0.73(95%CI:0.66-0.80,P<0.001)and 0.73(95%CI:0.65-0.81,P<0.001),respectively,while the cutoff values were 2.8(sensitivity:69.8%;specificity:64.0%)and 2.4(sensitivity:71.7%;specificity:60.6%),respectively.CONCLUSION Increased NLR and decreased LMR may predict LAAT/dense SEC in patients with nonvalvular AF.

The electrical design of a membrane antenna for a lunar-based low-frequency radio telescope

Detecting primordial fluctuations from the cosmic dark ages requires extremely large low-frequency radio telescope arrays deployed on the far side of the Moon.The antenna of such an array must be lightweight,easily storable and transportable,deployable on a large scale,durable,and capable of good electrical performance.A membrane antenna is an excellent candidate to meet these criteria.We study the design of a low-frequency membrane antenna for a lunar-based low-frequency(<30 MHz)radio telescope constructed from polyimide film widely used in aerospace applications,owing to its excellent dielectric properties and high stability as a substrate material.We first design and optimize an antenna in free space through dipole deformation and coupling principles,then simulate an antenna on the lunar surface with a simple lunar soil model,yielding an efficiency greater than 90%in the range of 12-19 MHz and greater than 10%in the range of 5-35 MHz.The antenna inherits the omni-directional radiation pattern of a simple dipole antenna in the 5-30 MHz frequency band,giving a large field of view and allowing detection of the 21 cm global signal when used alone.A demonstration prototype is constructed,and its measured electrical property is found to be consistent with simulated results using|S11|measurements.This membrane antenna can potentially fulfill the requirements of a lunar low-frequency array,establishing a solid technical foundation for future large-scale arrays for exploring the cosmic dark ages.

基于相关滤波的目标跟踪技术仿真分析

聚焦于计算机视觉领域中目标跟踪的应用热点问题,开展基于循环结构核算法(CSK)、核相关滤波算法(KCF)、颜色空间算法(CN)、自适应尺度多特征优化算法(SAMF)等典型算法的目标跟踪仿真验证。通过技术原理解析、指标评估体系构建、样本数据集构建与分析等具体实验环节实施,对算法的功能和性能进行对比,验证了各种算法的优缺点,为相关滤波算法在工程上的应用提供了依据。

冷轧镀锌线带钢翘曲产生原因及解决方案

某冷轧厂镀锌机组在生产过程中发现,2#卷取机下线钢卷存在纵向翘曲缺陷。本文主要介绍了针对该质量缺陷问题,通过理论计算分析,查找纵向翘曲产生的原因,同时结合现场工况提出并实施了改造方案,最终解决了2#卷取机下线钢卷翘曲缺陷,使带钢质量得到了有效提升。

Cu掺杂对Inconel 718合金Laves相稳定性的影响

采用第一性原理计算与实验相结合的方法,研究了Cu掺杂对Inconel 718合金中Laves相的影响。构建了Laves相Fe_(8)Nb_(4)晶胞的掺杂模型,计算分析了Cu掺杂前后体系的平衡晶格常数、形成热、结合能、电荷差分密度以及弹性常数等。计算结果表明,Cu元素掺杂Laves相后,体系发生晶格畸变,稳定性降低;Cu原子掺杂增加了Laves相的硬度,但对体系塑性的影响比较复杂。实验结果表明,Cu能够固溶到Laves相中,降低Laves相的固溶温度,Cu掺杂Laves相导致体系原子间结合强度的降低是造成Laves相固溶温度降低的本质原因。

鸢乌贼为蛋白源的方斑东风螺人工配合饲料养殖研究

【目的】鸢乌贼是丰富且极具开发潜力的软体动物资源,探究鸢乌贼作为方斑东风螺人工配合饲料蛋白源的可行性。【方法】设计7种鸢乌贼质量分数(33.1%、43.1%、53.1%、63.1%、73.1%、83.1%、100%)的方斑东风螺人工配合饲料,以杂鱼为对照,投喂初始体质量为0.37(±0.03)g的方斑东风螺,养殖试验期90d,以日均增重、日增长率、饲料系数、成活率和单位面积产量为指标,对养殖效果进行评价。【结果】以63.1%鸢乌贼处理的方斑东风螺日均增重0.034g、日增长率9.31%,显著高于对照处理的0.029 g和7.96%;该处理的饲料系数为1.33,显著低于对照处理的2.27;该处理的单位面积产量为3168.6 g/m^(2),高于对照处理(2856.8 g/m^(2)),但差异不显著;其他试验处理的日均增重和日增长率低于或显著低于对照处理。添加鸢乌贼处理的方斑东风螺成活率均低于对照处理,其中添加63.1%以上鸢乌贼的处理与对照处理无显著差异。【结论】该方斑东风螺人工配合饲料的使用无需清除残饵残渣,可减少养殖工作量;且可降低对杂鱼的依赖,保护近海渔业资源。从日均增重、日增长率及饲料系数来看,方斑东风螺人工配合饲料中添加鸢乌贼具有可行性,添加的质量分数参考值为63.1%。以鸢乌贼作为主要蛋白源,将成为方斑东风螺饲料发展的重要方向。

中厚板V型坡口GMAW电弧声信号焊缝偏差识别方法研究

针对中厚板V型坡口GMAW(熔化极气体保护焊)焊缝偏差识别问题,提出一种新型基于电弧声信号的中厚板GMAW摆动焊焊缝偏差识别方法。在V型坡口摆动焊接中,发现当摆动中心与焊缝中心出现偏差,电弧声信号呈现明显非对称性。为此,针对电弧声信号的时域和频域特征开展了进一步研究,明确了与焊缝偏差信号存在密切关联的电弧声摆动极限位置能量差、标准差、小波包第7频带和第8频带能量等特征参量。构建基于上述4类参量的GS-SVR非线性回归方程,通过电弧声特征信号检测,可实现焊接过程中焊接偏差信息的在线识别,通过左右偏差试验表明该模型具有良好精度,可满足工程实际生产需要。

4种饵料对玉足海参幼体生长和发育的影响

为了解单一饵料或混合投喂对玉足海参(Holothuria leucospilota)幼体生长的影响,采用2种单胞藻(牟氏角毛藻、球等鞭金藻)和2种酵母(酿酒酵母、海洋红酵母)单一或组合搭配投喂玉足海参耳状幼体,测定并比较海参幼体的体长、胃宽、水体腔长、变态成活率等指标。试验结果显示:单一饵料组中,牟氏角毛藻对玉足海参幼体体长的生长及变态存活最有利,而球等鞭金藻对其脏器(胃、水体腔)的发育最有利;综合所有处理组的投喂效果看,混合投喂组比单一饵料组更有利于玉足海参幼体的生长和存活,其中酿酒酵母+海洋红酵母的混合投喂组合得到了最高的体长、胃宽和水体腔长特定生长率,牟氏角毛藻+海洋红酵母投喂组的变态成活率最高,变态发育速度最快。结果表明,在玉足海参幼体培养早期适合以混合酵母为主投喂,后期则可较多投喂牟氏角毛藻和海洋红酵母。

住院患者应用PEG-ELP联合二甲硅油方案进行肠道清洁效果的影响因素分析

目的分析影响住院患者应用复方聚乙二醇电解质散(PEG-ELP)联合二甲硅油方案进行肠道准备效果的因素。方法回顾性分析行结肠镜检查的200例住院患者肠道准备的临床资料,分析肠道清洁效果的影响因素。结果经单因素分析结果显示,高血压、血脂异常、尿酮体阳性和下午行结肠镜检查是影响肠道准备清洁度的相关因素(P均<0.05)。多因素回归分析发现高血压[OR=2.270,95%CI(1.193,4.318),P=0.013]、血脂异常[OR=2.312,95%CI(1.245,4.293),P=0.008]、下午结肠镜检查时间[OR=2.377,95%CI(1.279,4.416),P=0.006]是结肠镜检查患者肠道准备清洁度不佳的独立危险因素。结论住院患者应用PEG-ELP联合二甲硅油方案进行肠道准备,高血压、血脂异常以及下午检查时间段是导致结肠镜检查肠道清洁效果差的独立危险因素。

芽孢杆菌对方斑东风螺生长、存活、免疫及消化酶活性的影响

为探究芽孢杆菌(Bacillus)是否可替代抗生素在方斑东风螺(Babylonia areolata)养殖中的应用,在方斑东风螺早期面盘幼虫到稚螺生长发育过程中,使用芽孢杆菌[凝结芽孢杆菌(B.coagulans)、地衣芽孢杆菌(B.licheniformis)]和抗生素(磺胺甲恶唑)进行人工调控,研究其对方斑东风螺生长、存活、免疫及消化相关酶活性的影响。结果显示,芽孢杆菌和磺胺甲恶唑均促进了方斑东风螺各性状指标的生长,两者之间差异不显著(P>0.05);芽孢杆菌组成活率在后期面盘幼虫阶段之后均显著高于对照组和磺胺甲恶唑组(P<0.05);芽孢杆菌能够提高机体碱性磷酸酶(AKP)、酸性磷酸酶(ACP)、过氧化氢酶(CAT)、过氧化物酶(POD)、谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、脂肪酶(LPS)和淀粉酶(AMS)活性,丙二醛(MDA)水平和总抗氧化能力(T-AOC),并且高于对照组和磺胺甲恶唑组。结果表明,在对方斑东风螺进行苗种繁育时适当使用芽孢杆菌(凝结芽孢杆菌、地衣芽孢杆菌)可以提高机体免疫力和抗病性,在一定程度上提高消化酶活性、促进幼体生长和提高成活率,且效果优于磺胺甲恶唑。

茶多酚对马氏珠母贝外套膜组织和细胞培养的影响

为改善马氏珠母贝(Pinctada martensii)外套膜组织和细胞体外培养的效果,探究了添加不同浓度的天然提取物茶多酚对外套膜组织和细胞培养液的优化效果。结果显示,当茶多酚的添加量为0.5%~2.0%(体积分数)时,马氏珠母贝外套膜细胞的生物活性显著高于对照组(P<0.05);当添加量为1.0%时,相对细胞生物活性最高。5组完全培养液(0%、0.5%、1.0%、1.5%、2.0%组)均能较好地促进细胞的生长增殖,且细胞的生长曲线均呈“S”型;当培养液中茶多酚的添加量为1.0%时,外套膜细胞增殖效果最优。研究表明,马氏珠母贝外套膜组织和细胞在最适培养液中均能大量增殖游离细胞,且正常分泌珍珠质,其中培养液中的钙离子(Ca^(2+))浓度随着组织和细胞增殖过程呈先减后增的趋势,但始终低于初始浓度。研究结果进一步优化了马氏珠母贝外套膜组织和细胞培养液,为推动马氏珠母贝无核珍珠的培育提供了理论基础。