Effect of Shrinkage Reducing Agent and Steel Fiber on the Fluidity and Cracking Performance of Ultra-High Performance Concrete

Due to the low water-cement ratio of ultra-high-performance concrete(UHPC),fluidity and shrinkage cracking are key aspects determining the performance and durability of this type of concrete.In this study,the effects of different types of cementitious materials,chemical shrinkage-reducing agents(SRA)and steel fiber(SF)were assessed.Compared with M2-UHPC and M3-UHPC,M1-UHPC was found to have better fluidity and shrinkage cracking performance.Moreover,different SRA incorporation methods,dosage and different SF types and aspect ratios were implemented.The incorporation of SRA and SF led to a decrease in the fluidity of UHPC.SRA internal content of 1%(NSRA-1%),SRA external content of 1%(WSRA-1%),STS-0.22 and STE-0.7 decreased the fluidity of UHPC by 3.3%,8.3%,9.2%and 25%,respectively.However,SRA and SF improved the UHPC shrinkage cracking performance.NSRA-1%and STE-0.7 reduced the shrinkage value of UHPC by 40%and 60%,respectively,and increased the crack resistance by 338%and 175%,respectively.In addition,the addition of SF was observed to make the microstructure of UHPC more compact,and the compressive strength and flexural strength of 28 d were increased by 26.9%and 19.9%,respectively.

Effect of Reducing Application of Chemical Fertilizers and Chemical Pesticides on Physiological Traits,Yield and Quality of Radish

This paper studied the effect of reducing application of chemical fertilizer,increasing application of functional organic fertilizer and trace elements and fully using biological pesticides on physiological traits,yield and quality of radish. The results showed that applying functional organic fertilizer and trace elements and fully using biological pesticides could help to significantly improve the radish fleshy root yield,increase soluble sugar and vitamin C content,reduce crude fiber and nitrate content,but had no significant influence on radish moisture content,glucosinolates and chlorpyrifos content in organophosphorus pesticides.

Chemical Analysis of NO_x Removal Under Different Reduced Electric Fields

This work presents a chemical kinetic analysis of different species involved in nitrogen-oxygen mixed gas induced by stationary corona discharge at room temperature and atmospheric pressure.This study takes into account twenty different chemical species participating in one hundred and seventy selected chemical reactions.The reaction rate coefficients are taken from the literature,and the density is analyzed by the continuity equation without the diffusion term.A large number of investigations considered the removal of NOx showing the effects of N,O and O3 radicals.The aim of the present simulation is to complete these studies by analysing various plasma species under different reduced electric fields in the range of 100-200 Td（1 Td=10-21 V·m^2）.In particular,we analyze the time evolution of depopulation（10^-9-10^-3s）of NOx.We have found that the depopulation rate of NO and NO2 is substantially affected by the rise of reduced electric field as it grows from 100 Td to 200 Td.This allows us to ascertain the important role played by the reduced electric field.

OPTIMIZATION OF A REDUCED CHEMICAL KINETIC MODEL FOR HCCI ENGINE SIMULATIONS BY MICRO-GENETIC ALGORITHM

A reduced chemical kinetic model （44 species and 72 reactions） for the homogeneous charge compression ignition （HCCI） combustion of n-heptane was optimized to improve its autoignition predictions under different engine operating conditions. The seven kinetic parameters of the optimized model were determined by using the combination of a micro-genetic algorithm optimization methodology and the SENKIN program of CHEMKIN chemical kinetics software package. The optimization was performed within the range of equivalence ratios 0.2-1.2, initial temperature 310- 375 K and initial pressure 0, 1-0.3 MPa, The engine simulations show that the optimized model agrees better with the detailed chemical kinetic model （544 species and 2 446 reactions） than the original model does.

Room Temperature and Reduced Pressure Chemical Vapor Deposition of Silicon Carbide on Various Materials Surface

At room temperature, 300 K, silicon carbide film was formed using monomethylsilane gas on the reactive surface prepared using argon plasma. Entire process was performed at reduced pressure of 10 Pa in the argon plasma etcher, without a substrate transfer operation. By this process, the several-nanometer-thick amorphous thin film containing silicon-carbon bonds was obtained on various substrates, such as semiconductor silicon, aluminum and stainless steel. It is concluded that the room temperature silicon carbide thin film formation is possible even at significantly low pressure, when the substrate surface is reactive.

Effect of Durian Peel Ash Added in Zinc Oxide/Reduced Graphene Oxide Composites Used as a Chemical Sensor for Hydrazine Detection

As the hydrazine is toxic, the methods to detect hydrazine at low concentrations are essential in scientific research. This preliminary study reported on how to increase the efficiency of ZnO/reduced graphene oxide (rGO) by adding durian peel ash (DPA) and using three-electrode method. The ZnO/rGO composites were prepared using chemical reaction of graphene oxide (GO) with zinc chloride. The rGO was prepared by the chemical reduction of GO using hydrazine. The properties of the samples were investigated using scanning electron microscopy, atomic force microscopy, X-ray diffraction, and Potentiostat/Galvanostat. The results showed that the optimal condition for the composite material was 70%DPA:30%ZnO/rGO with the sensitivity of 222.92 mA/mM·cm2 and the current density up to 116.50 ± 0.95 A/g. The relationship between the current and the hydrazine concentration was I (μA) = 48.69 + 21.91C (mM) with R2 of 0.9870. The minimum concentration of hydrazine solution that the modified electrode can measure was 0.125 mM. The DPA powder can then be used to enhance the hydrazine detection efficiency at low concentrations.

Sustainable Management of Rice Insect Pests by Non-Chemical-Insecticide Technologies in China

Chemical pesticides play crucial roles in the management of crop diseases and pests. However, excessive and irrational use of pesticides has become a major concern and obstacle to sustainable agriculture. As a result, the quality and security of agricultural products are reduced, and the ecological and environmental integrities are threatened. Recently, environment-friendly pest management measures have been introduced and adopted to manage rice insect pests and reduce the use of insecticides. This paper reviewed the advancements in development and application of non-chemical technologies for insect pest management during rice production in China.

Preparation of Conducting Poly N-methylaniline Microsphere and Its Antibacterial Performance to Sulfate Reducing Bacteria

Microspheres of conducting polymers poly N-methylaniline （PNMA） were successfully synthesized through oxidation of N-methylaniline without any template. The average diameter of the microspheres with a smooth surface was about 0.40 μm when 0.2 M N-methylanUine was oxidized with 0.2 M ammonium persulfate in 0.2 M of HClO4 solution. The size of microspheres can be controlled by changing reaction time and temperature. The acid concentration was critical for the formation of microspheres with smooth surfaces. The excellent antibacterial performance of PNMA in novolac epoxy coating to sulfate reducing bacteria was demonstrated. Moreover, in API media, PNMA inhibited growth of SRB and then reduced the corrosion rate of carbon steel remarkably.

Preparation of CeO_(2) abrasives by reducing atmosphere-assisted molten salt method for enhancing their chemical mechanical polishing performance on SiO_(2)substrates

Ce^(3+)as the active site on the CeO_(2)abrasive surface is the key to enhancing the material removal rate(MRR).The CeO_(2)abrasives with high chemical activity were prepared by the molten salt method under a reducing atmosphere.The crystal structure and morphology of CeO_(2)abrasive s were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),ultraviolet—visible diffuse reflectance spectroscopy(UV-Vis DRS),and X-ray photoelectron spectroscopy(XPS).The CeO_(2)abrasives were obtained under different atmospheres(Air,Ar,and Ar/H_(2)).With the enhancement of the reducing atmosphere,the morphology of the abrasives transforms from spherical to octahedral,while more oxygen vacancies and Ce^(3+)are generated on the surface of CeO_(2)abrasives.The CMP experiments show that the MRRs of the CeO_(2)-Air,CeO_(2)-Ar,and CeO_(2)-Ar/H_(2)abrasives on SiO_(2)substrates are 337.60,578.74,and 691.28 nm/min,respectively.Moreover,as confirmed by atomic force microscopy(AFM),the substrate surfaces exhibit low roughness(20.5 nm)after being polished using all of the prepared samples.Especially,the MRR of CeO_(2)-Ar/H_(2)abrasives is increased by 104.76%compared with CeO_(2)-air abrasives.The improved CMP performance is attributed to the increased Ce^(3+)concentration and the octahedral morphology of the abrasives enhancing the chemical reaction and mechanical removal at the abrasive-substrate interface.

稠油化学复合冷采技术研究与应用

我国稠油储量可观,其中60%的是深层稠油,而主流的蒸汽吞吐等热采技术采收率不足20%;稠油资源开发潜力极大,积极探索新的开采方式以提高采收率是石油领域高质量发展的必然选择。本文着重阐述稠油化学复合冷采技术体系构建及其现场应用,为中深层稠油的新型绿色低成本接替技术发展提供有效方案。在分析稠油组分的基础上,细致剖析稠油结构致黏机理,包括化学降黏机理、降低启动压力梯度机理、提高驱油效果机理在内的提高采收率机理,以丰富理论认识。面向工程应用亟需,从水溶性降黏剂分子设计与合成、自组装调堵剂研发两方面出发,突破稠油绿色化学驱油体系。基于发展的稠油化学复合冷采技术,完成了3个稠油油田示范工程应用,在提高产油量、控制含水率方面取得了良好成效。进一步梳理了分子采油理论与技术、渗流理论与数值模拟技术等方面的后续发展要点,以为深层稠油的绿色高效开发接替技术研究、稠油化学复合冷采技术推广应用研究等提供启发和参考。

2023年中国炼油工业发展状况及展望

2023年,中国炼油能力增长继续放缓,新增炼油能力1200万吨/年,总能力升至9.36亿吨/年,装置结构优化调整持续推进。2023年我国成品油需求快速反弹、市场整顿持续推进等利好因素推动炼油行业生产明显好转,多项主要生产经营指标显著回升。国家政策为我国炼油行业高质量发展指明了路径,炼油企业持续推进绿色、低碳、数字化、智能化发展,并积极“走出去、引进来”,扩大合作。展望未来,2024年中国炼油能力将继续较快增长,但能力峰值基本显现,预计炼油能力峰值将在2027年左右出现;“十五五”期间,我国炼油能力过剩的压力有一定缓解,但不能掉以轻心,淘汰落后产能、调整产品结构、节能降碳等转型升级措施需长期推进。

中药远志的炮制研究进展

远志是我国传统中药,具有安神益智、交通心肾、祛痰、消肿等作用,虽然其炮制方法多样,但炮制目的均在于减毒增效。本文对古法炮制中的净制、切制、加辅料炒与不加辅料炒等方法进行了文献概述,并在此基础上,对现代炮制前后化学成分变化及减毒增效机制等方面进行文献分析。现代研究表明,远志的减毒增效机制为远志皂苷的毒性与糖基含量有关,远志皂苷B水解为细叶远志皂苷后胃肠毒性显著降低。现代远志的炮制工艺主要有甘草炙远志、蜜制远志、厚朴汁炙远志、炆远志等,但厚朴汁炙远志、炆远志现代沿用不多,炮制工艺缺乏规范化研究。笔者认为,应加强古法炮制研究,在确定炮制工艺的同时,结合化学成分、药效等方面,开展炮制机制等方面的研究,为远志炮制的合理性提供科学依据,确保临床用药安全。

还原氧化石墨烯的可控制备及表征

化学氧化还原法是工业上较为成熟的一种制备还原氧化石墨烯(Reduced graphene oxide,RGO)的方法。本研究首先采用改进Hummers法氧化剥离石墨,在喷雾干燥条件下获得了片状氧化石墨烯(Graphene oxide,GO),然后分别采用维生素C(Vitamin C,VC)化学还原、快速升温热还原、慢速升温热还原、VC还原结合快速升温热还原法对GO样品进行还原,得到了四种RGO样品,并对其进行了全面的物理化学表征。结果表明,还原方法对RGO形貌结构及导电性有显著影响:采用VC化学还原可得到比表面积较大且具有微/介多级孔道的球状RGO,其还原程度低,导电性差;采用热还原可得到还原程度较高、导电性良好的片状RGO,并且较快的升温速率有利于发生膨胀剥离,可有效提高相应RGO样品的比表面积;VC还原与快速升温热还原相结合则可以得到比表面积和还原程度都较高的多孔球状RGO,但由于RGO颗粒之间较大的接触电阻,其导电性不及热还原得到的片状RGO。

能源转型下炼化行业发展趋势与企业竞争力分析

交通运输一直是世界石油需求的主要领域。由于能源转型加速、燃油效率提升,世界交通运输燃料需求将达峰值,石化原料需求将成为石油需求增长的主要动力。随着减油增化、新建乙烯等项目的推进实施,我国乙烯规模将继续高速增长,大宗基础化学品和通用合成材料规模也将大幅提升,结构性过剩压力日益增加。实施炼化结构调整,选择有竞争力的工艺流程、产品结构和工艺技术,采取节能降耗措施、加大降碳技术应用、提高低碳石化原料比例等手段已成为炼化企业高质量发展的必由之路。

重油催化裂解在炼化企业布局影响因素研究

随着我国炼化产业的快速发展,原油一次能力已接近10×10^(8)t/a,但汽柴油消费总量受经济结构转型、新能源替代等因素影响,汽油需求量即将达峰,柴油需求量已呈现下降趋势。与之相对应的,乙烯、丙烯的下游化工产品未来仍有一定增长空间。重油催化裂解装置相较常规催化裂化可大幅减少汽柴油产量、增产化工原料,已成为炼化企业实现“减油增化”转型升级的重要路径之一。在具体项目布局规划时,由于炼化企业装置结构、所处地域市场条件等情况不同,分析企业是否适宜布局该装置是决策者的主要难点。结合催化裂解技术特点,总结分析了“企业所在地油品过剩程度、减油增化程度、化工品目标市场、资源利用程度、苯资源平衡、催化裂解原料性质、存量资产利用程度、投资回报率”共八项影响重油催化裂解项目决策实施的主要因素,为投资决策者提供支持依据。

3T磁共振直肠小视野APT成像

目的化学交换饱和转移(CEST)成像技术已成为诊断与脑部和全身疾病代谢相关变化的有用工具,通过计算与水分子相邻化合物的可交换质子的含量进行定量分析。具体而言,酰胺质子转移(APT)CEST技术通过比较可交换的内源性蛋白质或肽的含量变化来区分正常组织与脑卒中和脑肿瘤组织。在体内的小器官病变诊断中,小视野(rFOV)成像技术已被广泛应用,本研究旨在应用rFOV成像技术来识别直肠中的CEST信号,探讨rFOV成像技术在直肠疾病临床诊断中的潜在效用,并为直肠疾病的放化疗提供代谢影像信息。方法使用3.0T磁共振成像扫描仪对11名健康志愿者进行了横断面全视野(Full_FOV)和rFOV CEST成像。设置的分辨率分别为2.5×2.5×6 mm3和1.5×1.5×6 mm3。采用了0.7μT和2μT两种预饱和脉冲。rFOV成像采用了ZOOM成像方法。对于2μT的饱和脉冲,采用了±3.5 ppm的MTRasym方法进行定量分析,而对于0.7μT的饱和脉冲,则采用Lorentzian Difference的方法来量化CEST的对比度图和曲线。结果相较于Full_FOV成像,rFOV方法可以在保持较好对比度的同时将扫描时间减半。与Full_FOV方法相比,rFOV成像方法可以得出与Full_FOV方法几乎相同的Z谱和MTRasym曲线。此外,以大约3 min的时间可以实现1.5 mm×1.5 mm分辨率的rFOV成像。这种r FOV成像方法可以更好地显示出整个直肠的解剖细节,包括CEST成像对比图及定量分析曲线。结论CEST MRI在直肠疾病诊断方面具有较高价值,采用rFOV技术可以提供更高的空间和时间分辨率。由于其在直肠疾病诊断方面的潜力,CEST MRI可以作为临床诊断直肠疾病的首选。

化肥减量配施有机肥对木薯生长及根际土壤细菌菌群的影响

为了研究化肥减量配施有机肥对木薯根际土壤细菌多样性和群落结构及产量的影响,采用Illumina Nova 6000测序平台,对未施肥(CK)、有机肥(T_(1))、常规施肥+有机肥(T_(2))和化肥减施+有机肥(T_(3))等施肥方式处理下的华南12号木薯根际土壤进行16S rRNA高通量测序分析。结果表明,与CK相比,T_(3)处理不仅能显著增加木薯株高和茎粗,还能提高木薯产量。在相似水平为97%下聚类分析得到木薯根际土壤OTUs,分别为3603个(CK)、1688个(T_(1))、1276个(T_(2))和3317个(T_(3))。不同施肥方式改变土壤细菌的多样性和丰度,其物种多样性由高到低依次为:CK>T_(3)>T_(1)>T_(2)。基于土壤细菌群落的PCoA和聚类分析,CK和T_(3)细菌群落结构组成较为相似,T_(1)与T_(2)细菌群落结构组成相似。不同施肥处理下木薯根际土壤中优势菌门为变形菌门、拟杆菌门、酸杆菌门、厚壁菌门、放线菌门和绿弯菌门。化肥减施配施有机肥增加了变形菌门、拟杆菌门和放线菌门的相对丰度,降低了厚壁菌门和绿弯菌门的相对丰度。冗余性分析结果表明速效钾是影响木薯根际土壤菌群的主要效应因子。研究表明,化肥减量配施有机肥不仅能增加木薯的产量,还能改变木薯根际土壤细菌群落结构和多样性,为发展绿色、高效、可持续的木薯产业提供坚实的理论支撑。

邵阳市植烟田杂草种类分析及防控研究

旨在有效防控邵阳市植烟田杂草,维护大田烟草健康生长,调查了植烟田的杂草种类并归纳分析,在前期优选除草剂混配(乙羧氟草醚+砜嘧磺隆)基础上,通过施药后30 d除草效果调查,验证自制助剂的增效作用。结果表明,邵阳市植烟田杂草共有42种,隶属于22科,广泛分布于各植烟田。自制助剂混配除草药剂有较好的除草效果,施药后30 d,砜嘧磺隆+乙羧氟草醚+助剂3000倍液总株防效95.44%,总鲜重防效达到97.19%,且对烟草安全。供试自制助剂+除草剂可以减施增效,可为烟草杂草的有效防控提供参考。

化肥减量配施对盐碱稻田土壤改良效果研究

研究化肥减量及其与有机肥、土壤调理剂和功能肥配施对盐碱稻田土壤肥力、细菌群落多样性及水稻生长发育的影响,以期为该地区盐碱稻田化肥减量增效提供理论依据。通过连续两年田间试验,以水稻‘1747’为供试材料,共设5个施肥处理,分别为100%化肥(CF)、化肥减量20%(RF)、化肥减量20%配施有机肥(OF)、化肥减量20%配施土壤调理剂(SC)、化肥减量20%配施功能肥(FF)。结果表明,RF较CF处理降低土壤pH和可溶性盐总量,降幅分别为0.58%和7.17%,且在减量施肥条件下,OF、SC和FF处理显著降低土壤Na^(+)、Ca^(2+)、HCO_(3)^(-)、Cl^(-)含量,同时提高土壤肥力。化肥减量配施处理(OF、SC、FF)提高土壤细菌群落多样性,同时改变土壤细菌群落门结构,增加放线菌门、变形菌门和芽单胞菌门等富营养菌群,减少绿弯菌门和酸杆菌门等贫营养菌群。RDA分析表明,影响细菌群落门结构的主要因素为有效磷、速效钾和全氮。与CF处理相比,化肥减量配施处理(OF、SC、FF)增加水稻穗长、穗粒数、千粒重及产量,增幅分别为3.56%~6.48%、11.20%~24.95%、8.81%~6.28%、6.04%~18.39%。综合分析,化肥减量20%配施功能肥提高土壤肥力和细菌群落多样性,从而促进水稻生长发育,可实现盐碱土壤改良、水稻生产可持续的目的。

“双碳”目标下石油炼制技术研发策略与工业实践

百年石油炼制行业面临着“双碳”目标和第三次能源转型带来的燃料需求量持续减少的双重挑战,而传统石油炼制技术追求高转化率,造成石油资源碳氢利用效率低,CO_(2)排放高,与“减排增效”的转型发展目标相悖。为此,基于石油分子管理理念,以产品高选择性为石油炼制技术研发策略,开发出变革性的小分子烷烃加工、重油加工和低碳烯烃生产技术并进行工业实践,实现源头降碳和过程降碳,满足石油炼制行业向绿色低碳、减油增化、清洁生产方向转型日益迫切的需求。