Cluster and Condensed Phase Properties of Light Elements (especially B, C, N, Na and Si)

Amorphous forms of C will first be compared and contrasted with amorphous Si, the differences in chemical bonding being emphasized in relation to atomic structure. After a brief discussion of ordered layers of graphite and of BN, some attention will be focused on BN cages and polymers and on C nanotubes. Finally properties of Na metal clusters will be discussed, including fission of such charged clusters

Elastic properties of disordered binary hcp-Fe alloys under high pressure: Effects of light elements

The effects of light elements on the elastic properties of disordered binary hcp-Fe alloys were investigated at high pressures using plane-wave density functional theory combined with the Monte Carlo special quasi-random structure method.We found that the increase in the O content in hcp-Fe had a more pronounced effect on the sound velocity than Si,S,and C.The longitudinal wave velocity was decreased by∼6%with 2%O content,which was a much greater decrease than the values of 0.6%and 2%induced by the same content of Si and S,respectively,under high pressures.Compared with the other three light elements,the longitudinal wave velocity of the Fe-C alloy exhibited the most gradual decreasing with increasing C content.In addition,the effects of different O and S contents on the anisotropy of hcp-Fe alloys strongly depended on the variation in pressure,whereas the pressure only slightly affected the anisotropy of Fe-Si alloy systems.

Light alloying element‐regulated noble metal catalysts for energy‐related applications

Noble metals have been widely used as heterogeneous catalysts because they exhibit high activity and selectivity for many reactions of both academic and industrial interest.The introduction of light atomic species(e.g.,H,B,C,and N)into noble metal lattices plays an important role in optimizing catalytic performance by modulating structural and electronic properties.In this review,we present a general overview of the recent advances in the modification of noble metals with light alloying elements for various catalytic reactions,particularly for energy‐related applications.We summarize the types,location,concentration,and ordering degree of light atoms as major factors in the performance of noble metal‐based catalysts,with emphasis on how they can be rationally controlled to promote activity and selectivity.We then summarize the synthetic strategies developed to incorporate light elements and highlight the theoretical and experimental methods for understanding the alloying effects.We further focus on the wide usage of noble metal‐based catalysts modified with different light alloying atoms and attempt to correlate the structural features with their catalytic performances.Finally,we discuss current challenges and future perspectives regarding the development of highly efficient noble metal‐based catalysts modified with light elements.

The Performance of Small Diameter Aluminum Light Support Structures Containing Handholes under Cyclic Fatigue

Aluminum light poles play a pivotal role in modern infrastructure, ensuring proper illumination along highways and in populated areas during nighttime. These poles typically feature handholes near their bases, providing access to electrical wiring for installation and maintenance. While essential for functionality, these handholes introduce a vulnerability to the overall structure, making them a potential failure point. Although prior research and analyses on aluminum light poles have been conducted, the behavior of smaller diameter poles containing handholes remains unexplored. Recognizing this need, a research team at the University of Akron undertook a comprehensive experimental program involving aluminum light poles with handholes containing welded inserts in order to gain a better understanding of their fatigue life, mechanical behavior, and failure mechanisms. The research involved testing seven large-scale aluminum light poles each 8-inch diameter, with two separate handholes. These handholes included a reinforcement that was welded to the poles. Finite Element Analysis (FEA), statistical analysis, and comparison analysis with their large counterparts (10-inch diameter) were used to augment the experimental results. The results revealed two distinct failure modes: progressive crack propagation leading to ultimate failure, and rupture of the pole near the weld initiation/termination site around the handhole. The comparison analysis indicated that the 8-inch diameter specimens exhibited an average fatigue life exceeding that of their 10-inch counterparts by an average of 30.7%. The experimental results were plotted alongside the fatigue detail classifications outlined in the Aluminum Design Manual (ADM), enhancing understanding of the fatigue detail category of the respective poles/handholes.

Correlations between Light Rare Earth Elements in Soil and Navel Orange Tree System in Gannan Area

The total content of light rare earth elements( LREEs) in the soil of navel orange orchards of Gannan area is greater than that of heavy rare earth elements( HREEs). Appropriate content of LREE can not only promote the growth of navel oranges,and it is also conducive to human health. On the basis of exploring the correlations between the content of LREE in the soil of navel orange orchards of Gannan area and the contents of LREE in navel orange leaves and fruit,the influence mechanism of LREEs on the quality of navel oranges was revealed. In this study,with two Newhall navel orange orchards with different soil LREEs background levels in Xinfeng County as the research object,the changes in the content of LREE( lanthanum,La; cerium,Ce; praseodymium,Pr; neodymium,Nd) in leaves and fruit of navel orange at different growth stages were analyzed using Inductively Coupled Plasma-Mass Spectrometry( ICP-MS),and the correlations between the content of LREE in the soil,navel orange leaves and navel orange fruit were studied. The results showed that the contents of the four kinds of LREEs in the soil ranked as Ce > La > Nd > Pr,and there were significant differences among them( P < 0. 01). Navel orange leaves and fruit have selective and heterogenic absorption for LREEs. At different growth stages,La showed the highest accumulation amount in the leaves and fruit of navel orange; and the content of LREE in the leaves of navel orange increased first and then decreased,while that in the fruit of navel orange showed continuous decrease. During the migration of LREEs from soil to leaves to fruit,the content of LREE decreased rapidly as the migration distance increased. The accumulation amount of LREE in navel orange was positively correlated with the content of LREE in the soil. The correlation between the content of LREE in the leaves and fruit of navel orange was greatest. Among the four kinds of LREEs,the correlation of La was greatest,followed by Ce,indicating that the accumulation amount of LREE in the navel orange body was affected by the element types.

Selective Separation of Light and Heavy Rare Earth Elements from the Pregnant Leach Solution of Apatite Ore with D2EHPA

Different separation techniques such as solvent extraction, ion exchange, and precipitation are often used for recovery of rare earth elements (REEs) from pregnant leach solutions obtained from acid leaching. Solvent extraction is generally accepted as the most appropriate commercial technology for separating REEs due to the need to be able to handle larger volumes of diluted pregnant solutions. This study focused on the development of selective separation of light and heavy REEs from the pregnant leach solution obtained from leaching of apatite ore in 1 M sulfuric acid (H2SO4) using solvent extraction. Three different commercial organophosphorus extractants (di-(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC88A) and tributyl phosphate (TBP)), and the influences of experimental parameters such as extractant concentration, organic/aqueous phase ratio, diluent type, pH, extraction time and stripping agent concentration were examined. Results showed that light REEs (LREEs) and heavy REEs (HREEs) in the pregnant leach solution were selectively separated with D2EHPA via a two-stage extraction process. In the first-stage of solvent extraction, >90% of (0.05 g/L) HREEs was extracted with 1.8 M D2EHPA in kerosene while the vast majority (>95%) of LREEs was remained in raffinate. In the second-stage, >93% (1.01 g/L) of LREEs was extracted from the raffinate with 1.8 M D2EHPA dissolved in kerosene at pH 1.6. HREEs (>95%) and LREEs (>90%) loaded with D2EHPA after the first and second-stage of extraction were stripped by 4 M H2SO4 and 1 M H2SO4 solutions, respectively. Distribution of middle rare earth elements (MREEs) was discussed through the extraction processes in this study.

立德树人背景下轻化工助剂课程思政的思考与探索

基于立德树人的理念,对学生加强思想政治教育受到了业界广泛的关注。专业课在高校人才培养体系中占有重要地位,在不同的专业课程中根据学科背景和专业特色融入思政教育内容是实现知识传授、能力培养和立德树人相结合的重要举措。结合“轻化工助剂”课程特色和优势,指出轻化工助剂开展课程思政的意义,深入挖掘了课程思政元素,积极探索实施路径。

轻元素荧光分析用多层膜分光晶体的制备与表征

物质组分与结构分析是认知和研究物质的重要方式。利用X射线荧光光谱分析法可以对物质中的元素进行定性分析与定量检测,该方法是目前最为常规的物质组分和结构无损分析手段之一。在使用波长色散型X射线荧光光谱仪探测轻元素时,多层膜分光晶体是核心的光学元件。使用人工多层膜晶体代替普通晶体作分光晶体,可有效提升分析仪器对轻元素的检测能力。针对国产波长色散型X射线荧光光谱仪分析轻元素的实际需求,设计出了Mo/B4C,Cr/C,Cr/Sc,W/B4C(周期厚度d=3.63 nm)和W/B4C(周期厚度d=2.85 nm)多层膜分光晶体,分别适用于B,C,N,O,F五种轻元素的荧光探测。利用磁控溅射的方式,在尺寸为50 mm×30 mm的超光滑Si基底上完成了五种多层膜晶体的制备。采用高分辨率X射线衍射仪对各个多层膜晶体进行掠入射X射线反射测试,测试及拟合结果表明:五种多层膜晶体膜层结构规整、界面宽度小、成膜质量高,膜层均匀性好,整个镜面上周期厚度的均匀性误差均在1%以内。采用原子力显微镜表征了各个多层膜晶体的表面形貌,结果表明:五种多层膜晶体表面颗粒状结构尺寸较小,表面形貌平滑,表面粗糙度小。最后,通过模拟计算获得了各个多层膜晶体在掠入射工作角度下的反射率,分别为:Mo/B4C(30.1%@B-Kα线),Cr/C(29.3%@C-Kα线),Cr/Sc(35.4%@N-Kα线),W/B4C(d=3.63 nm,8.6%@O-Kα线),W/B4C(d=2.85 nm,10.7%@F-Kα线)。基于以上研究,所制备的五种多层膜分光晶体可以满足波长色散型X射线荧光光谱仪的需求,能够应用在B,C,N,O,F五种轻元素的探测中。

非连续光对无土栽培番茄苗期无机元素吸收的影响

本研究在人工光型植物工厂中采用岩棉种植番茄植株,分析了在总光量一致的基础上红光背景下蓝光补充介入和蓝光取代介入两种非连续供光模式对番茄植株营养液无机元素吸收及叶片色素光谱参量的影响。结果表明,与连续红光相比,蓝光以不同方式介入均降低了番茄叶片中K元素含量而提高了茎中K元素含量,蓝光介入一定程度上抑制了番茄K元素由茎向叶片的运输;蓝光以不同方式介入均提高了番茄地上部中Mg含量(增幅8.93%~13.63%),而降低了地上部Fe含量(降幅28%~48%)及Mn含量(降幅3.93%~21.24%)。其中蓝光补充介入模式下番茄叶片中Mg元素含量随着蓝光补充强度的升高而增加,叶片Mg含量在蓝光取代介入模式下高于蓝光补充介入模式而地上部Fe含量趋势则相反,蓝光取代介入的非连续光模式较蓝光补充介入模式而言更有利于刺激叶片中Mg的积累而抑制地上部Fe的积累。与连续红光相比,蓝光以不同方式介入后番茄叶片色素光谱参量Hue值(色相角)和MCARI值(修正叶绿素吸收比指数)均有所提高,相反,Red/Green值(红绿区域光谱反射比)均有所降低,蓝光补充介入模式下叶片Hue值和MCARI值随蓝光补充强度的升高而增大,R/RB_(80)处理下Hue、MCARI值最高,较对照分别提高4%、124%;蓝光取代模式下Hue值和MCARI值随蓝光间歇时间的延长先增大后减小,R/RB_((1h))处理下Hue、MCARI值最高,较对照分别提高6%、215%。番茄叶片在绿光波段的反射率与各处理下Hue、MCARI值变化趋势接近,而番茄叶片中Mg元素含量与叶绿素光谱参量呈正相关性。蓝光取代介入的非连续光模式较蓝光补充介入模式而言更有利于刺激叶片类胡萝卜素分解和叶绿素积累,非连续供光模式通过调控番茄植株无机元素的吸收进而作用于叶片色素的形成。本研究为无土栽培番茄光环境调控提供了理论依据。

转光棚膜对‘翠碧1号’烟苗生长及养分积累的影响

为探究转光膜在南平烟区烟草育苗中的应用效果,以‘翠碧1号’为试验材料,设普通聚乙烯棚膜和转光棚膜2个试验处理,研究转光膜对育苗棚内光照、温度和烟苗生长、养分积累的影响。结果表明,转光膜可调节育苗棚内光照和温度,转光膜处理育苗棚内13:00和14:00的光合有效辐射强度和透光率低于普通膜,而15:00和16:00的光合有效辐射强度和透光率高于普通膜。通过分析育苗棚内温度日变化发现,转光膜处理育苗棚内白天(8:00—16:00)的温度低于普通膜处理,其他时间高于普通膜处理。转光膜促进烟株的生长,与普通膜相比,转光膜处理的根系总根长、根表面积、根系体积、分支数等指标和根系干重、总干重显著高于普通膜处理。转光膜显著影响了养分的吸收和积累,转光膜处理烟苗地上部氮含量、地下部钙含量、整株磷含量和铜含量显著高于普通膜处理,而地上部钙含量和镁含量低于普通膜处理;转光膜处理促进了烟苗氮磷钾的累积。转光膜通过调节育苗棚内的光强和温度,促进烟苗生长和养分吸收,提高烟苗干物质和养分积累量。

土壤-超积累植物体系中稀土元素的空间富集-分异特征与富集机理

离子吸附型稀土矿是我国南方特色的优质稀土资源,但由于落后的采矿方式和无节制的开采,大量稀土元素(稀土元素+Y,简称稀土元素)被带入环境中,导致稀土矿区周边出现许多环境污染和植被退化问题。乌毛蕨是一种对稀土元素具有较强耐受性和超强富集能力的蕨类超积累植物,能被用于稀土污染土壤或尾矿的生态修复。本研究以离子吸附型矿区表生土壤上生长的稀土超积累植物乌毛蕨及其根际土为研究对象,通过化学消解和ICP-MS方法测定根际土、根表、根部、叶柄、叶片中稀土元素的含量,分析土壤–植物体系中稀土元素的空间分布、富集与分异特征;采用顺序提取法测定土壤中不同化学形态的稀土元素含量,同时利用微区X射线荧光光谱(μ-XRF)与扫描电镜能谱分析技术(SEM-EDS),阐明乌毛蕨对稀土元素的吸收与富集机理。化学测试结果表明,乌毛蕨对稀土元素有较强的富集和地上转运能力,富集系数(BF)和转移系数(TF)分别为2.61和2.85;植物器官富集能力顺序为:叶片(1750μg/g)>根部(512μg/g)>叶柄(56.5μg/g);植株整体稀土元素配分模式具有与根际土相似的富轻土元素和Ce负异常特征,不同的是,植株整体Eu无异常(根际土δEu=0.51);根际土壤中富集离子交换态的轻稀土离子(34%~64%,(La/Yb)N=2.36),与根系表面呈轻微富轻稀土元素((La/Yb)N=1.29)的现象暗示根际大部分轻稀土元素能以离子形式被根系吸收,重稀土元素与有机配体络合而被吸附在根系表面;稀土元素在向上迁移过程中,(La/Yb)N值下降(叶柄=27.63,叶片=17.17),揭示木质部伤流液的重稀土元素可能比轻稀土元素更容易向上迁移;μ-XRF与SEM-EDS结果显示,乌毛蕨地上部的超富集器官(叶片)将稀土元素主要储存在叶缘的表皮层细胞,且能将大部分非生理需要的稀土元素有效区室化。上述认识揭示了在离子吸附型稀土矿区表生环境中,稀土元素从土壤向植物体内迁移并在地上部富集与分异的过程、规律和主要原因,为今后利用稀土超积累植物实现植物采矿或稀土尾矿生态修复提供科学认知基础。

不同形态河谷沉积物中稀土元素的粒径分布特征

稀土元素(REE)作为一种重要的土壤侵蚀示踪元素,明确其含量随土壤颗粒粒径的变化特征,对准确量化土壤侵蚀速率具有重要意义。本研究基于Samonova等采样测定的不同粒径范围(<1、1~10、10~50、50~250和250~1 000μm)土壤/沉积物颗粒中的REE含量,分析了俄罗斯普罗特瓦河左岸河谷形态(“U”和“V”形谷)、地貌部位(坡面、沟坡/沟壁、沟道底部和洪积扇)、侵蚀(坡面、沟坡/沟壁)和沉积(沟道底部和洪积扇)环境对土壤/沉积物REE含量、富集系数等的影响。结果表明:(1)“U”和“V”形谷四类地貌下,轻稀土(LREE)、重稀土(HREE)和总稀土(ΣREE)含量均随颗粒粒径变粗呈降低趋势。在相同地貌部位,“U”形谷细颗粒(<50μm)中LREE、HREE和ΣREE含量较“V”形谷分别低14.6%~24.7%、10.0%~33.5%和14.2%~21.1%。(2)无论河谷形态和地貌部位,LREE和HREE均明显富集在细颗粒中,尤其是“V”形谷,LREE和HREE主要富集在<10μm的颗粒中。(3)对比侵蚀和沉积区,“U”和“V”形谷沉积区细颗粒中LREE和HREE的富集程度均显著(P<0.05)大于侵蚀区。可见,无论河谷形态、地貌部位和侵蚀沉积区,REE均主要富集在细颗粒中;但河谷形态和侵蚀、沉积对REE含量的粒径分布有重要影响。

基于碳纳米管和聚二甲基硅氧烷的光声换能器研究

为探究激光参数、光声转换层厚度对光声换能器输出声压的影响,本研究通过COMSOL仿真软件建立了光声换能器的物理模型。首先,基于聚二甲基硅氧烷(polydimethylsiloxane, PDMS)和碳纳米管(carbon nanotube, CNT)分别建立CNT、CNT-PDMS转换层模型;其次,改变激光脉冲持续时间和转换层厚度,对转换层输出声压进行测量;最后,对激光脉冲持续时间和转换层厚度所引起换能器输出声压强度的改变进行分析。结果表明,当CNT和CNT-PDMS转换层的厚度均为200μm、激光脉冲持续时间分别在10~30 ns和50 ns左右时,换能器能输出较高声压强度的超声波。仿真结果对光声换能器的研究有一定的指导意义。

基于ANSYS的卡车轮毂有限元分析与尺寸优化

利用ANSYS Workbench软件对重型卡车轮毂进行静力学分析。在汽车静止仅承受12 T重量载荷的条件下对轮毂进行径向载荷分析,得到轮毂的应力云图和变形云图。通过分析结果,提出结构改进方案并按照优化方案对轮毂中冗余部分进行尺寸优化,通过比对分析优化后的结果确定合理的优化范围以达到轻量化设计的目的。从而在满足强度要求的同时既能降低生产成本又能节约能源。

光照对树番茄幼苗碳、氮、磷、钾元素积累与分配的影响

【目的】研究树番茄幼苗在不同光照环境下碳(C)、氮(N)、磷(P)、钾(K)元素的积累和分配,为园林应用及林下种植提供理论依据。【方法】以一年生树番茄幼苗为研究对象,设置4种不同光照强度(100%、75%、50%、25%NR,NR为自然光照),观测树番茄幼苗生长发育形态参数,分析生物量、元素积累与分配格局。【结果】树番茄苗高、地径、各器官生物量基本随光照强度的减小先增后降,50%NR下最大,根冠比不断减小,全光照下根冠比最大;不同遮阴程度下树番茄幼苗各器官C含量相对稳定,叶和细根的N、P含量均有不同程度的增加,茎N、P含量有不同程度的降低。随光照程度的减弱,树番茄幼苗除粗根外,其余器官K含量均有不同程度的提高。不同处理各器官C、N、P、K积累量均为叶、茎中最大。随光照程度的减弱,树番茄幼苗地上部分C、N、P、K分配比例增加,地下部分分配比例减少。树番茄幼苗粗根C、N,细根N、P含量与各器官生物量、C、N、P、K含量无显著关系(P>0.05)。茎生物量与粗根生物量呈极显著正相关(P<0.01)。【结论】50%遮阴环境下,树番茄幼苗苗高、地径增长最大,同时增加对地上部分投入及减少对地下部分投入来适应低光环境。室外栽培、林下推广种植以及园林应用中可选择50%遮阴环境,有助于生物量、元素含量和积累量的增加。

基于HOE的全息显示双目视差构建方法

全息光学元件(Holographic Optical Element,HOE)是全息三维显示的重要器件之一。为了解决HOE用于双目全息显示时视差不匹配的问题,本文提出并实现了一种基于HOE的全息显示双目视差构建方法,同时对元件成像时的像差进行了分析校正。通过对HOE的制作原理和成像规律分析,结合光线跟踪技术渲染的虚拟模型和现实场景模型,设计了基于HOE的全息双目显示系统,提出了双目视差构建方法,即在获取人眼坐标位置时为观察者实时提供包含双目视差关系的视点图像。通过进一步分析全息显示系统内部的图像畸变产生原因及过程,提出了去畸变的优化处理算法。实验结果表明,提出的方法不仅能够实现HOE实时显示全息三维图像,而且解决了HOE在全息双目显示中视差不匹配以及成像畸变的问题。

快速行走式沟槽支护装备结构分析与优化

针对城乡管网改造和乡村雨污分流工程的沟槽开挖施工中,传统支护方式造价高、适用范围有限、施工时间长、需配备大型设备辅助等问题,设计了一套快速行走式沟槽支护装备。所设计的支护装置具备能自主行走、一定的宽度适应性、灵活轻便且易于安装。为实现轻量化设计和模块化安装,对所设计的沟槽支护装备的关键零部件进行了设计与计算,并利用有限元方法对关键零部件在不同工况下进行了结构受力分析,对剪叉机构、销钉、吊钩、护板等进行了受载计算与有限元分析。分析结果表明,所设计的支护装置能满足安全性与可靠性要求。为沟槽开挖施工提供了安全可靠的辅助装备,有效提高了施工效率缩短施工周期。

要素与感知:安全感及偏好评价下的大学校园夜间环境研究

夜间环境是大学校园基础设施体系的重要组成部分,但却忽视了对人本需求的挖掘。以苏州市16个大学校园户外空间为例,聚焦使用者的安全感及偏好,开展日间、夜间校园环境要素的实地调研。通过日夜差值法定量探讨光环境要素与安全感的关联性,进一步识别影响夜晚整体偏好的主要环境因素及其阈值,最后建立基于综合感知的环境参数范围。结果显示,大学校园夜间环境更新设计应优先考虑夜间光环境,其次是景观特征。综合安全感及偏好的条件下,优先推荐平均水平照度范围为13~17lx,路面平均亮度范围为0.7~0.9cd/m2。研究为大学校园夜间环境更新设计及精准实施提供数据支撑,提升使用者主观感知,促进可持续校园环境的建设。

基于向日葵原理的光伏发电自动追光装置设计

【目的】为进一步提高光伏发电的效率,开发了一种基于向日葵原理的光伏发电自动追光装置。【方法】该装置集成了光伏板、中部控制板、双轴追光系统、GPS定位系统、自我保护系统和自动储能等模块,可以实时捕捉太阳位置,保持太阳光在光伏板上的最大直射面积,从而提高光的转化率。同时,安装在光伏板上的压力电阻和热敏电阻可以有效减少恶劣环境对设备的影响,从而延长设备的使用寿命。【结果】为检验光伏板中的支架是否满足强度要求,对该部件进行有限元分析。计算结果显示,支架屈服强度为6.204e+02 MPa,满足设计要求。同时,对制作的样机进行性能测试。实验结果表明,所制作的样机各项性能符合要求,平均发电量提升了约19.56%,发电效率显著提升。【结论】该光伏发电装置在精准定位和自动捕光方面具有显著的优势,有一定的市场推广价值。

基于ANSYS的某车架有限元分析和轻量化设计

车架作为汽车的主要承载部件,其在移动时所受的载荷十分复杂,其强度刚度及稳定性的变化直接影响着整个行车的安全性和舒适性。车架设计的重点之一,就是在保证车架的力学强度,刚度和动力学稳定性的基础上,尽可能地把重量降到最轻,设计得更合理,并且尽可能地减少车架的过渡部分残余应力集中。本论文ansys分析为核心,在对江淮货车车架进行建模,对其进行满载弯曲,紧急制动,紧急转向等常见工作情况的应力及变形进行有限元分析,实现对整个车架进行轻量化和参数化设计。