激光诱导击穿光谱(LIBS)分析虚拟仿真实验

虚拟仿真实验作为大型仪器分析实验教学模式的新兴趋势,有效地将虚拟仿真技术与实物仪器教学相结合,最大限度地提升了学生对于大型仪器分析的综合应用能力。本文以激光诱导击穿光谱(LIBS)虚拟仿真实验系统为例,完整地模拟了LIBS系统的样品处理、光谱采集、定性分析和定量分析等实际实验场景,通过虚实结合实验教学模式对实验过程进行实时跟踪与综合考评。该实验有助于提高学生自主探究能力和创新意识,培养具有独立思考与实践能力的拔尖人才。

点石成色:敦煌壁画的彩色世界

敦煌壁画,作为中国古代艺术的瑰宝,是一个丰富的历史、文化、艺术和宗教文化遗产宝库,其价值不可估量。这些壁画所用的颜料,皆为天然矿物精心挑选而成,它们为敦煌壁画带来了独一无二的色彩与质感。深入理解这些颜料的特性,有助于我们更好地欣赏艺术、文化和历史的深厚底蕴,也是壁画保护与修复的基础。本文采用生动拟人化的叙述方式,通俗易懂地描绘了莫高窟壁画的色彩来源,重点阐述了常用典型的矿物颜料及其来源,旨在促进壁画的保护工作,以及文化遗产的普及、宣传和传承。

危化品王国的奇妙之旅

实验室的化学品种类繁多,其中有一类极具危险的化学品,它们时常引发各类事故,但又在人类生活中有着十分重要的作用,这就是危险化学品。在实验室中大家总是无法避免接触这类化学品,因此认识危化品,分辨它们的危险属性,确保正确储存和规范使用至关重要。本文以和平大使淇淇的视角,带大家走进危险化学品国度里的各个部落,介绍实验室危险化学品的分类以及储存方法,让大家了解并从容面对他们,并且能够安全使用,避免实验室危险事故的发生。

以梦为马,诗“酒”趁年华

酒,乃天地之精华,文化之载体,品一杯佳酿,如同品一段历史,品一份人生。白酒在各种场合中发挥着重要作用,它不仅仅是一种饮品,还寄托着人们对美好生活的向往和追求。本文采用生动形象的对话形式,通俗易懂地描述了白酒酿制的五个主要过程——选料、糖化、发酵、蒸馏和陈酿,重点介绍了其中的主要化学成分以及酿制过程中的化学反应,白酒的酿造过程体现了匠心独运的精神以及酒文化的博大精深。通过品味白酒,可以更好地感悟人生的哲理和智慧。好酒需要陈放才能更加醇香,人生也需要经历岁月的沉淀才能更加丰富多彩。

基于Raman光谱的3,5-二氨基-1,2,4-三唑(DAT)合成反应在线监测与反应机理探究——推荐一个仪器分析综合实验

本实验介绍了一个仪器分析综合性实验——基于Raman光谱的3,5-二氨基-1,2,4-三唑(DAT)合成的在线监测与反应机理探究。该实验是一个科研转化的仪器分析综合实验,内容包括DAT的合成、基于Raman光谱的合成反应过程在线监测以及合成反应机理解析。在实验中,采用化学计量学方法对Raman光谱数据进行处理和分析,以更深入地理解合成反应的机理。通过本实验,可以巩固学生的化学专业知识,提高学生的综合实验操作技能,激发学生对科学研究的兴趣,培养学生的科研探究能力。

人工智能时代背景下的仪器分析科教融合模式探索

针对传统仪器分析方法在应对更复杂的化学样品、更微量的化学分析和更精准的化学测量要求时所遇到的挑战,本文提出了一种将人工智能融合入科学仪器分析的应用研究和教学实践的策略。通过采用科学研究新范式,探讨分析仪器的研发与应用,在科教融合视域下,借助人工智能新方法提升实验教学效果,并实现虚拟仿真实验、智能实验数据分析和多元化智能评价等方面的融合。通过运用人工智能新技术,紧扣时代发展趋势,培养具备全面科学素养、创新能力和社会责任感的高素质人才,进而落实高等教育立德树人根本任务。

基于STEM教学理念的分析化学实验教学新模式探索--以“自来水硬度测定”为例

STEM是一种集科学、技术、工程、数学多学科融合的项目式教育理念,旨在通过融合多学科知识完成项目目标,从而培养学生提出问题、分析问题以及解决问题的能力,进而激发学生的科学探索精神和创新思维能力,已经成为当前国际教育研究和改革的热点。本文将STEM教育理念引入分析化学实验教学过程中,探索发展分析化学实验课程教学新模式。倡导以学生为中心、以真实问题为牵引,学生以相关课程理论为线索,自主完成实验方案设计、实验过程、实验结果分析等一系列分析化学实验过程,从而培养学生的科学探索与实践能力。主要从课程内容、教学方法以及考核方式等三个方面来探索分析化学实验教学新模式,进而提高分析化学实验的教学质量和学生的学习兴趣和科学素养。

线上线下深度融合的分析化学实验教学新模式探索--以“维生素C饮料中抗坏血酸含量的测定”为例

为了提高实验课程教学效果,提升学生的学习兴趣,培养学生的科学探索精神,充分利用线上教学平台辅助分析化学实验教学。以“维生素C饮料中抗坏血酸含量的测定”实验为例,建立线上线下深度融合的实验课教学模式,优化整个实验教学过程,记录学生的学习过程,改进实验成绩评价方式。该模式可以激发学生的实验热情,使学生的学习由被动变主动,满足学生个性化的学习需求,还有助于培养学生的严谨的科学态度、安全环保意识和实践创新能力,从而实现创新型人才培养。

A new oil spill detection algorithm based on Dempster-Shafer evidence theory

Features of oil spills and look-alikes in polarimetric synthetic aperture radar(SAR)images always play an important role in oil spill detection.Many oil spill detection algorithms have been implemented based on these features.Although environmental factors such as wind speed are important to distinguish oil spills and look-alikes,some oil spill detection algorithms do not consider the environmental factors.To distinguish oil spills and look-alikes more accurately based on environmental factors and image features,a new oil spill detection algorithm based on Dempster-Shafer evidence theory was proposed.The process of oil spill detection taking account of environmental factors was modeled using the subjective Bayesian model.The Faster-region convolutional neural networks(RCNN)model was used for oil spill detection based on the convolution features.The detection results of the two models were fused at decision level using Dempster-Shafer evidence theory.The establishment and test of the proposed algorithm were completed based on our oil spill and look-alike sample database that contains 1798 image samples and environmental information records related to the image samples.The analysis and evaluation of the proposed algorithm shows a good ability to detect oil spills at a higher detection rate,with an identifi cation rate greater than 75%and a false alarm rate lower than 19%from experiments.A total of 12 oil spill SAR images were collected for the validation and evaluation of the proposed algorithm.The evaluation result shows that the proposed algorithm has a good performance on detecting oil spills with an overall detection rate greater than 70%.

A novel strategy for quantitative analysis of soil pH via laser-induced breakdown spectroscopy coupled with random forest

pH is one of the significant properties of soil,and is closely related to the decomposition of soil organic matter,anion-cation balance,growth of plants and many other soil processes.In the present work,laser-induced breakdown spectroscopy(LIBS) technique coupled with random forest(RF) was proposed to quantify the pH of soil.First,LIBS spectra of soil was collected,and some common elements in soil were identified based on the National Institute of Science and Technology database.Then,in order to obtain a better predictive result,the influence of different input variables(full spectrum,different spectral ranges,the intensity of characteristic bands and characteristic lines) on the predictive performance of RF calibration model was explored with the evaluation indicators of root mean square error(RMSE) and coefficient of determination(R2),the characteristic bands of four elements(AI,Ca,Mg and Si) were determined as the optimal input variables.Finally,the predictive performance of RF calibration model was compared with partial least squares calibration model with the optimal input variables and model parameters,and RF calibration model showed a better predictive performance,and the four evaluation indicators of R_p^2,RMSEP,mean absolute error and mean relative error were 0.9687,0.1285,0.1114 and 0.0136,respectively.It indicates that LIBS technique coupled with RF algorithm is an effective method for pH determination of soil.

Variant selection map of external load during Ni_(4)Ti_(3) precipitation in nitinol:a theoretical and phase field study

The morphology of Ni_(4)Ti_(3) precipitates is important in tuning the martensitic transformation(MT)behavior and mechanical properties of nitinol.Constrained ageing is effective in engineering the morphology of Ni_(4)Ti_(3) precipitates due to the variant selection effect of external load which is still lacking.In this work,maps of variant selection effect of external load applied along all crystallographic directions are obtained by using a combination of theoretical analyses and phase field simulations.It is found that maps produced by uniaxial tension and uniaxial compression are quite different.The number and types of Ni_(4)Ti_(3) variants preferred by external load vary as the loading direction changes.Moreover,factors influencing the strength of variant selection effect are discovered.This work provides insights on understanding the Ni_(4)Ti_(3) precipitation process and sheds light on the engineering of morphology of Ni_(4)Ti_(3) precipitates for desired mechanical and functional properties.

Design of titanium alloys by additive manufacturing:A critical review

Additive manufacturing(AM)is an innovative technology that creates objects with a complex geometry layer-by-layer,and it has rapidly prospered in manufacturing metallic parts for structural and functional applications.Recent literatures have investigated the effect of different AM technologies on the microstructure evolution of titanium alloys.However,metal AM has mostly been regarded only as a shaping technology for near-net-shape manufacturing.A huge advantage of AM in alloy design and treatments has been largely overlooked at the present time.In this paper,we systematically reviewed the interaction of AM processes and different Ti-alloys,as well as the possible ways for mechanical property enhancements.On the one hand,the complex thermal histories caused by AM influence the phase transformation of Ti-alloys.On the other hand,the unique thermal and processing features of AM provide ways and opportunities to design new Ti-alloys with unachievable microstructures and properties by conventional methods.The aim of this paper is thus to provide a new perspective on the relationship between the AM process and alloy design,which is to consider AM as an irreplaceable material treating and design method.Only an integrated consideration of both AM process and alloy design can successfully achieve materials with superior properties for applications in the future industries.

Structure of human lysine methyltransferase Smyd2 reveals insights into the substrate divergence in Smyd proteins

The SET-and myeloid-Nervy-DEAF-1(MYND)-domain containing(Smyd)lysine methyltransferases 1–3 share relatively high sequence similarity but exhibit divergence in the substrate specificity.Here we report the crystal structure of the full-length human Smyd2 in complex with S-adenosyl-L-homocysteine(AdoHcy).Although the Smyd1–3 enzymes are similar in the overall structure,detailed comparisons demonstrate that they differ substantially in the potential substrate-binding site.The binding site of Smyd3 consists mainly of a deep and narrow pocket,while those of Smyd1 and Smyd2 consist of a comparable pocket and a long groove.In addition,Smyd2,which has lysine methyltransferase activity on histone H3-lysine 36,exhibits substantial differences in the wall of the substrate-binding pocket compared with those of Smyd1 and Smyd3 which have activity specifically on histone H3-lysine 4.The differences in the substrate-binding site might account for the observed divergence in the specificity and methylation state of the substrates.Further modeling study of Smyd2 in complex with a p53 peptide indicates that mono-methylation of p53-Lys372 might result in steric conflict of the methyl group with the surrounding residues of Smyd2,providing a structural explanation for the inhibitory effect of the SET7/9-mediated mono-methylation of p53-Lys372 on the Smyd2-mediated methylation of p53-Lys370.

Heterogeneous precipitate microstructure in titanium alloys for simultaneous improvement of strength and ductility

The design of alloys with simultaneous high strength and high ductility is still a difficult challenge.Here,we propose a new approach to designing multi-phase alloys with a synergistic combination of strength and ductility by engineering heterogeneous precipitate microstructures through the activation of different transformation mechanisms.Using a two-phase titanium alloy as an example,phase field simulations are carried out firstly to design heat treatment schedules that involve both conventional nucleation and growth and non-conventional pseudospinodal decomposition mechanisms,and the calculated microstructures have been evaluated by crystal plasticity finite element modeling.According to simulations,we then set a two-step heat treatment to produce bimodalα+βmicrostructure in Ti-10V-2Fe-3Al.Further mechanical testing shows that the ductility of the alloy is increased by~50%and the strength is increased by~10%as compared to its unimodal counterpart.Our work may provide a general way to improve the mechanical properties of alloys through multiscale microstructure design.

Molecular basis for the functions of dominantly active Y35N and inactive D60K Rheb mutants in mTORC1 signaling

Dear Editor,Mammalian target of rapamycin complex 1(mTORC1)serves as a central regulator of cell growth and proliferation by integrating signals from growth factors,nutrients,energy status,and cellular stress(Saxton and Sabatini,2017).A small GTPase,called Ras homolog enriched in brain(Rheb),is a positive regulator of mTORC1.Like other small GTPases,the function of Rheb is dictated by its guanine nucleotide binding states:it is active in the GTP-bound form and inactive in the GDP-bound form(Aspuria and Tamanoi,2004).

Assessment of the electrical penetration of cell membranes using four-frequency impedance cytometry

The electrical penetration of the cell membrane is vital for determining the cell interior via impedance cytometry.Herein,we propose a method for determining the conductivity of the cell membrane through the tilting levels of impedance puises.When electrical penetration occurs,a high-frequency current freely passes through the cell membrane;thus,the intracellular distribution can directly act on the high-frequency impedance pulses.Numerical simulation shows that an uneven intracellular component distribution can affect the tilting levels of impedance pulses,and the tilting levels start increasing when the cell membrane is electrically penetrated.Experimental evidence shows that higher detection frequencies(>7 MHz)lead to a wider distribution of the tilting levels of impedance pulses when measuring cell populations with four-frequency impedance cytometry.This finding allows us to determine that a detection frequency of 7 MHz is able to pass through the membrane of Euglena gracilis(E.gracilis)cells.Additionally,we provide a possible application of four-frequency impedance cytometry in the biomass monitoring of single E.grailis cells.High-frequency impedance(≥7 MHz)can be applied to monitor these biomass changes,and low-frequency impedance(<7 MHz)can be applied to track the corresponding biovolume changes.Overall,this work demonstrates an easy determination method for the electrical penetration of the cell membrane,and the proposed platform is applicable for the multiparameter assessment of the cell state during cultivation.