古铜钙长无球粒陨石NWA 14701后成合晶富硫化物结构的成因研究

后成合晶在HED族陨石中较为罕见,对其中次生结构的研究有助于了解其母体岩浆期后矿物的变质作用,甚至可以揭示与含挥发分流体有关的交代作用过程。本次工作在Howardite NWA 14701的三相后成合晶中发现存在“富钙普通辉石-陨硫铁-SiO_(2)相(SRT-Ⅰ)”和“紫苏辉石-陨硫铁-少量SiO_(2)相(SRT-Ⅱ)”两种富硫化物结构,而在一些后成合晶相邻的鳞石英中还出现富硫化物交代结构(SRT-Ⅲ)。通过详细分析后成合晶岩屑的岩相学和矿物化学特征,认为NWA 14701后成合晶中SRT-Ⅰ和SRT-Ⅱ两种富硫化物结构分别为原亚稳态富铁辉石和后成合晶中的富铁橄榄石与富S蒸汽发生硫化作用的产物。此外,富S蒸汽亦交代了后成合晶相邻的鳞石英颗粒形成第三种富硫化物结构(SRT-Ⅲ)。本次工作在HED族陨石后成合晶岩屑中发现存在三种矿物硫化作用的痕迹。硫化作用可发生在HED族陨石母体演化过程的不同时间段,其中富铁辉石的硫化作用应是相对早期的过程,而富铁橄榄石的硫化作用则是一个相对晚期的过程。

富油煤研究进展与趋势

富油煤是集煤、油、气属性于一身的煤基油气资源,针对国内“相对富煤、缺油、少气”的能源禀赋,开发富油煤对缓解我国紧张的油气资源供应局势、实现煤炭的绿色开发和低碳利用具有重要的意义。以富油煤为主要关键词,通过CNKI和Web of Science数据库检索自1985-2023年底已公开发表的学术论文和专利,统计分析富油煤的发展历程和主要研究内容,梳理了富油煤研究的热点方向与前沿领域,展望了未来发展趋势。研究发现:富油煤热解、赋存特征及沉积环境、孔隙和分子结构、焦油产率预测、微生物降解、资源潜力及开发利用是当前富油煤研究热点内容。富油煤含有热解可生成油气的富氢结构,如脂肪结构的侧链与桥键及缩合芳香核周缘的弱键结构;富油煤多形成于陆相沉积物供应稳定、气候温暖湿润、强还原条件下的沉积环境;孔隙结构影响富油煤的热解反应效率、焦油析出和油气运移,而分子结构(主要为脂肪族氢含量和富氢弱键)决定了富油煤的生油潜力;富油煤通过微生物的水解、发酵、产氢产乙酸和产甲烷4个阶段向油气转化。随着地质选区技术瓶颈突破及多学科交叉与融合,富油煤富油性评价指标与预测方法、富氢组分的来源与定量判识、原位开发围岩封闭性及其评价方法、微生物降解与热解联作技术将成为今后研究的热点方向。研究成果为厘清当前富油煤的研究方向和未来走势奠定了基础。

基于富水性结构指数法的直罗组地层富水性评价

为评价陕北侏罗纪煤田顶板直罗组砂岩含水层富水性,综合分析了砂岩裂隙含水层富水性的影响因素,通过筛选并确定了含水层等效厚度、砂泥比、岩心采取率、砂泥岩交互层数等4个独立评价指标,构建了基于富水性结构指数法的含水层富水性评价方法。以金鸡滩井田为例,采用富水性结构指数方法评价了直罗组砂岩裂隙含水层的富水性。研究表明,以孔隙度、渗透性及粒度构造的富水性结构指数消除了各个影响因素之间的关联性,能够反映砂岩含水层富水性;利用砂岩等效厚度,将不同粒度砂岩统一转化为粗砂岩作为评价砂岩含水层富水性的指标;结合抽水试验获得的水文地质参数与富水性分区图进行对比,以G值为0.15作为直罗组含水层富水弱区与富水较强区的分界值,富水性弱区主要分布在西南部和东北部,验证了富水性结构指数法为陕北侏罗纪煤田覆岩富水性评价提供了一种有效预测途径。

微小RNA-195通过靶向抑制PH结构域富亮氨酸重复蛋白磷酸酶2表达参与香烟烟雾诱导急性肺损伤机制研究

目的:探究miR-195通过靶向抑制PH结构域富亮氨酸重复蛋白磷酸酶2(PHLPP2)表达参与香烟烟雾诱导急性肺损伤的机制。方法:选择90只健康小鼠,均分为A、B、C三组,使用香烟烟雾暴露建立小鼠急性肺损伤模型,A组为正常对照组,B组为低剂量干预组,C组为高剂量干预组,干预后检测三组小鼠肺泡灌洗液中肿瘤坏死因子(TNF-α)、白介素-8(IL-8)及基质金属蛋白酶9(MMP-9)水平,对比三组小鼠肺泡灌洗液中白细胞、中性粒细胞计数,对比三组小鼠肺组织中髓过氧化物酶(MPO)、超氧化物歧化酶(SOD)及谷胱甘肽(GSH)水平,最后检测三组小鼠肺组织中miR-195及PHLPP2蛋白表达量。结果:①肺泡灌洗液中TNF-α、IL-8及MMP-9水平C组>B组>A组,组间对比差异具有统计学意义(均P<0.05);②肺泡灌洗液中白细胞、中性粒细胞计数C组>B组>A组,组间对比差异具有统计学意义(均P<0.05);③肺泡灌洗液中MPO、SOD、GSH水平C组>B组>A组,组间对比差异具有统计学意义(均P<0.05);④肺组织中miR-195表达C组>B组>A组,PHLPP2蛋白表达C组<B组<A组,组间对比差异具有统计学意义(均P<0.05)。结论:香烟烟雾能够诱导小鼠肺组织出现炎性改变,其机制可能与miR-195过表达并抑制PHLPP2蛋白表达有关。

水热法制备富锂型Li_(2+4x)Mn_(0.6+2x)Ni_(0.6-6x)Cr_(0.8)O_4及其结构与电化学特性

采用水热法制备了系列富锂尖晶石型正极材料Li2+4xMn0.6+2xNi0.6-6xCr0.8O4(x=1/30,1/20,1/15,1/12),通过X射线衍射(XRD)、电感耦合等离子体-原子发射光谱(ICP-AES)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、傅里叶变换红外光谱(FTIR)、拉曼光谱、循环伏安(CV)和充放电测试等手段对其结构及电化学性能进行表征.结果表明,所制备的系列材料为富锂型高电压尖晶石结构正极材料,该系列样品在4.7 V左右有放电平台.x=1/15和x=1/12时,样品中的Cr为+3价,没有观测到Cr6+.随着x值的增大,样品中Li离子与过渡金属离子的混排减小,样品的充放电比容量逐渐增大,且2.7 V处的放电平台容量也增加.当x=1/12时,样品具有较好的充放电比容量和倍率特性,首次放电比容量为107.3 mA·h/g,20次循环后容量保持率为84.9%.

C=N诱导TiO_(2)表面富电子结构及其光催化性能

引入3种不同的吡啶类化合物调控TiO_(2)表面结构并利用其分子中C=N不饱和键的吸电子作用,使TiO_(2)表面电子富集,提升金红石TiO_(2)的光催化能力。通过扫描电镜(SEM)、X射线光电子能谱仪(XPS)、瞬态光电流响应(i-t)、紫外-可见光(UV-Vis)等手段,研究表面富电子结构对TiO_(2)纳米棒的微观形貌、表面电子结构、表面能带结构和光电化学响应能力方面及其对光解水性能的影响。结果表明:C=N的缺电子结构为催化剂表面电子富集提供场所,使光生载流子迁移路径增加,有利于光生电子-空穴对的分离,使其禁带宽度减小,有效地提升催化剂的光响应能力。其中TiO_(2)-PD具有较高的产氢速率,产氢性能可达39mmol/(g·h)。

陕北富油煤分子模型构建及其热解提油分子动力学特性

【目的】富油煤结构复杂,热解反应过程与机理不明晰,需要进一步研究富油煤结构与其热解产物分布的构效关系,明晰富油煤热解提油机理。【方法】以陕北典型富油煤为研究对象,结合^(13)C NMR、FTIR和XPS等表征方法,计算并构建富油煤分子模型,分子式为C_(444)H_(380)O_(74)N_(8)S。基于构建的富油煤分子模型,通过ReaxFF MD对陕北富油热解产物分布、热解特性以及焦油生成机理进行了深入分析。【结果和讨论】结果表明,陕北富油煤具有大量脂肪侧链和桥键等富氢结构,受热容易分解生成焦油和气体等挥发分。温度和升温速率对富油煤热解产物分布影响显著,模拟热解温度在1500 K时富油煤没有完全反应,挥发性产物质量分数为7.8%;模拟热解温度升高至2000~3000 K时,分子及自由基碎片运动越剧烈,二次反应也更明显。随着升温速率的增加,气体产物降低,而焦油产物先增加后减少;升温速率在100~200 K/ps时,富油煤没有完全热解,导致挥发分产率低于36%。根据热解产物分布推测,陕北富油煤热解反应机理是富油煤大分子中富氢结构受热断裂形成自由基碎片,进一步发生热解生成轻质焦油、重质焦油和气体产物。

富油煤的油气资源属性与绿色低碳开发

黄河中上游是国家大型煤炭基地集中分布区,也是我国富油煤的主要生产区。受我国“缺油、少气、相对富煤”资源禀赋特点的制约,煤炭安全绿色开采,清洁低碳利用已成为保障国家能源安全的重大需求。实现黄河流域富油煤开发与生态环境保护协调发展,对缓解我国油气供应紧张、保障能源战略安全具有重要的科学价值和现实意义。富油煤是集煤油气属性为一体的煤炭资源,其油气潜力、特殊性、关键地质问题亟需研究,绿色低碳化开发技术亟待探索。①富油煤主要赋存于中低阶煤类中,主要特点是富含较多富氢结构;在隔绝空气加热时,可生成油、气和半焦。半焦主要成分为固定碳,与无烟煤相近;气体的主要成分是CH_(4),H_(2),CO等,可以作为燃料气和原料气;油为煤焦油,类似于重质石油,可通过前处理、加氢精制和加氢催化裂化工艺等达到清洁燃料油标准;②富氢结构是富油煤具有油气资源属性的物质基础,研究富氢结构的岩石学、沉积学特征及变化规律,分析富氢结构物质来源、沉积转化、变质演化、聚集规律及地质驱动机制,是构建富油煤预测模式与评价理论的基础;③梯级利用和原位热解是富油煤绿色低碳开发的重要途径。富油煤地面热解-气化一体化、热解-化工-发电一体化技术可以实现清洁高效利用,井下原位热解有望破解清洁低碳利用的难题。其中,矿井式原位热解技术通过井巷工程布置方式,利用井下巷道开展煤层分割、保温封闭,通过煤层原位加热实现井下热解生产油气;钻孔式原位热解技术通过注热孔加热和油气抽采孔回收油气,也可借助人工辅助造缝,实现加热回收油气。将富油煤作为煤基油气资源管理和开发,是新时代煤炭工业高质量发展的重要方向。

组合赋权法在含水层富水性评价中的应用

侏罗系中统基岩裂隙含水层是神南矿区煤矿生产面临的主要充水含水层,以张家峁井田为例,选取了影响含水层富水性的砂岩等效厚度、砂泥岩厚度比、岩芯采取率和砂泥岩互层层数等4个指标,采用层次分析法和变异系数法求取各指标组合权重,改进了传统的富水性结构指数的数学模型,对张家峁井田煤层顶板侏罗系中统基岩裂隙含水层的富水性进行评价。研究表明:组合赋权法既可以避免主观赋权过程中人为因素干扰过重的缺点,又可以避免客观赋权过程中权重与实际不符的缺点;以富水性结构指数G′=0.06、0.13作为侏罗系中统基岩裂隙含水层富水性强弱的分区阈值,所取得的评价结果可以更客观、准确地评价煤层顶板富水性,为矿井防治水工作提供参考依据。

路易斯结构式的探讨

文章介绍了Lewis结构、八隅体理论的基本概念以及Lewis结构式的书写方法。着重探讨了缺电子结构和富电子结构的Lewis结构式的判断和正确书写等问题。

隧道空间对高密度电法在掌子面及侧壁富水构造探测中的影响研究

在隧道中进行高密度电法探测时,由于全三维正反演算法计算量大,建模较为困难,通常采用半空间假设的二维正反演算法进行计算,而实际隧道更接近于三维全空间模型,因此半空间假设会给视电阻率计算和反演结果带来误差。为研究高密度电法在隧道富水结构探测时采用半空间假设计算视电阻率带来的误差水平,以及对反演结果的影响,本文首先建立隧道三维模型,然后采用数值计算方法计算了三维隧道模型的准确视电阻率值,并将三维模型计算的装置系数带入反演的正演迭代过程,定量分析了半空间假设时对视电阻率和反演结果带来的影响。结果表明,在掌子面探测时,真实视电阻率是半空间假设计算结果的0.66~1.0倍;而在隧道侧壁探测时,该比值在0.9~1.6范围内。但半空间假设计算的视电阻率值的空间特征与真实值基本一致,而且误差较大的视电阻率值大多位于高密度电法的低分辨率区域内,对反演结果的影响较小。模拟结果表明了基于半空间假设的反演算法在隧道探测中的反演误差可以忽略,为实际工程应用提供了理论依据。

基于混合自动编码器道路语义分割方法研究

道路检测是无人驾驶汽车环境感知的重要环节,利用计算机视觉技术实现对环境场景的语义分割是确保无人驾驶汽车安全行驶的关键技术之一。提出一种稀疏自动编码器和去噪自动编码器相结合的混合自动编码器语义分割模型,利用稀疏自动编码器的稀疏性语义编码和去噪自动编码器鲁棒的语义编码,使混合模型学习的特征更有利于图像的语义分割。通过建立一种合理的模型排列顺序与堆叠形式,实现对图像语义的优化选择,从而建立一个具有深度的“富结构”语义分割模型,进一步提高语义分割性能。实验表明,本文所提模型更为简单、训练周期短,具有较好的综合图像分割性能。

结膜吸吮线虫中富亮氨酸结构域蛋白的筛选及生物信息学分析

目的对结膜吸吮线虫分泌蛋白基因组数据进行注释分析,筛选出富亮氨酸结构域蛋白,分析预测该基因序列及其编码蛋白质的结构和功能。方法对结膜吸吮线虫基因组进行结构分析和注释,在分泌蛋白组中筛选富亮氨酸结构域蛋白基因序列,利用ExPASY、DNAstar、MEGA 7.0等生物信息学软件预测分析其编码蛋白的理化性质、抗原表位等,并进行同源序列比对分析;建立系统发育树,进行系统进化分析。结果从结膜吸吮线虫分泌蛋白组中筛选出1条含有完整编码框的富亮氨酸结构域蛋白基因序列,其长度为2 439bp,编码812个氨基酸。编码蛋白相对分子质量(Mr)为204.001 24×103,为疏水性蛋白,含一个信号肽,无跨膜区,且含有较多抗原表位,与盘尾丝虫同源序列相似性为66%。结论生物信息学分析结膜吸吮线虫富亮氨酸结构域蛋白含有抗原表位,故该蛋白及其编码基因序列可作为诊断抗原和疫苗候选分子,也为该蛋白的功能研究了提供基础数据。

Analysis on Fuji Apple Tree Structures and Related Factors under Different Pruning Modes

To determine the correlations between the tree structuresof Fuji apple with different pruning modes and each factor, the data about 3 tree structures which were free spindle short shoot, free spindle long shoot and slenderspindle short shoot in Xingtang County of Hebai Province were investigated, then by SPSS anal- ysis, the correlations between the taperingness and each growth factor of inserted small branch were compared. The results showed that the taperingness of central trunk of free spindle dwarf-shoot Fuji apple treeshad negative correlations with each factor of inserted small branch, while the taperingness of central trunk of free spin- dle long-shoot Fuji apple treeshad positive correlations with each factor of inserted small branch, the taperingness of central trunk of slenderspindle short-shootFuji ap- ple treeshad negative correlation with total thickness of inserted small branch, but had positive correlations with other factors. This study can provide a scientifictheo- retical basis for the pruning technology of high-density planting trees grafting by dwarfing self-rooted rootstock.

Modeling the Cysteine Rich Domain of Plant Metallothionein-like Protein

With the progress of plant genome research, more than 50 plant metallothionein_like (MT_L) genes have been found, but only several MT_L proteins have been detected and no experimental structural information for MT_L proteins has been reported so far. Since detailed knowledge of the protein tertiary structure is required to understand its biological function, a method is needed to determine the structure of these proteins. In this study, the structural data of known mammal MT was used to determine the interatomic distance constraints of the CXC and CXXC motifs and the metal_sulfur chelating cluster. Then several possible MT conformations were predicted using a distance geometry algorithm. The statistical analysis was used to select those with much lower target function values and lower conformation energies as the predicted tertiary structural models of the cysteine_rich (CR) domains of these proteins. A suitable prediction method for modeling the CR domain of the plant MT_L protein was constructed. The accurately predicted result for the known structure of an MT protein from blue crab suggests that this method is practicable. The tertiary structures of CR domains of rape MT_L protein LSC54 was then modeled with this method.

Floristic and structural analysis of the woodland vegetation around Dello Menna,Southeast Ethiopia

Floristic composition and vegetation structure were described for the woodland vegetation around Dello Menna, Bale zone, southeast Ethiopia. A total 50 （20 m ×20 m） quadrats were sampled to identify and describe plant community types, species diversity, richness and evenness and to relate the identified plant community types with some environ- mental factors and describe the population structure of woody plant species. In each quadrrat, data on species identity, abundance, height and Diameter at Breast Height （DBH） of woody plant species, altitude and slope were recorded. Vegetation classification was performed using PC - ORD software package. Sorensen＇s similarity coefficient was used to detect dissimilarities among communities. Shannon - Wiener diversity index, species richness and Shannon＇s evenness were computed to de- scribe species diversity of the plant community types. Results show that a total of 171 vascular plant species representing 53 families were re- corded. Fabaceae is the dominant family represented by 13 genera and 26 species （15%） followed by Asteraceae, Lamiaceae and Anacardiaceae with eight species each （4.6%）. Based on the results of vegetation classi- fication, three plant communities （Dalbergia microphylla community, Grewia bicolar- Acacia brevispica community, and Combretum molle- Combretum collinum community） are recognized and described. Species richness, diversity and evenness varied among the plant communities.Species richness and diversity exhibit a bell - shaped pattern along alti- tude. Species turn over among communities more or less follow altitud- inal gradients. Tukey＇s pairwise comparison of means among the plant community types shows significant variations in altitude, implying that altitude is one of the most important factors determining the distribution of plant communities. The community Dalbergia microphylla type exhibits the highest species richness and diversity. Analysis of population structure of the dominant species reveals various patterns. Future research directions and recommendations are suggested for the sustainable utilization.

Precursor-modified strategy to synthesize thin porous amino-rich graphitic carbon nitride with enhanced photocatalytic degradation of RhB and hydrogen evolution performances

The photocatalytic activity of carbon nitride(CN)materials is mainly limited to small specific surface areas,limited solar absorption,and low separation and mobility of photoinduced carriers.In this study,we developed a precursor-modified strategy for the synthesis of graphitic CN with highly efficient photocatalytic performance.The precursor dicyandiamide reformed by different acids undergoes a basic structural change and transforms into diverse new precursors.The thin porous amino-rich HNO_(3)-CN(5H-CN)was calcined by dicyandiamidine nitrate,formed by concentrated nitric acid modified dicyandiamide,and presented the best photocatalytic degradation rate of Rh B,more than 34 times that of bulk graphitic CN.Moreover,the photocatalytic hydrogen evolution rate of 5H-CN significantly improved.The TG-DSC-FTIR analyses indicated that the distinguishing thermal polymerization process of 5H-CN led to its thin porous amino-rich structure,and the theoretical calculations revealed that the negative conduction band potential of 5H-CN was attributed to its amino-rich structure.It is anticipated that the thin porous structure and the negative conduction band position of 5H-CN play important roles in the improvement of the photocatalytic performance.This study demonstrates that precursor modification is a promising project to induce a new thermal polycondensation process for the synthesis of CN with enhanced photocatalytic performance.

A Comparative Study of Fish Assemblages Near Aquaculture, Artificial and Natural Habitats

Habitat plays a critical role in regulating fish community structure. Using the data collected from a monthly trammel net survey in Ma'an archipelago off the east coast of China, we evaluated impacts of five different habitats(artificial reefs, mussel farms, cage aquaculture, rocky reefs and soft bottom) on fish assemblages. This study suggests that artificial reefs(AR) have significantly higher species richness, abundance and diversity than mussel farms(MF) or soft bottom(SB) habitats during most seasons, and that fish taxa in the AR habitats are similar to those in the rocky reef(RR) habitats. Two different fish assemblage patterns were revealed in the study area using non-metric multidimensional scaling ordination: an assemblage dominated by reef fishes(especially by Scorpaenidae species) in AR, RR and cage aquaculture(CA) habitats and an assemblage dominated by Sciaenidae species in MF and SB habitats. We suggest that reef fishes play a key role in differentiating fish community structures in the study area. Although few differences in fish abundance and diversity were found between the CA and SB habitats, a more diverse age structure was observed in the CA habitats. A much more complex fish assemblage and enhanced population of local species were established as a result of the presence of both floating and fixed artificial structures, probably through improved survival rates.

Occurrence characteristics and enrichment regularity of indium in pyrite: A case study of Dachang tin ore-field

To reveal the occurrence state and enrichment regularity of the dispersed element indium in pyrite, the petrology,mineralogy, geochemistry, and mineral physics were researched detailedly. The results suggest that the structure of pyrite is mainlycomposed of massive structure, disseminated structure, vein structure, reticular structure, comb structure and so on. Generally, thepyrite coexists with sphalerite, marmatite, pyrrhotite, chalcopyrite, galena, and arsenopyrite. And the texture of pyrite primarilyconsists of the metasomatic texture, solid solution texture, idiomorphic?hypidiomorphic granular texture, and disseminated texture.The content of indium in pyrite ranges from 0.491×10?6 to 65.1×10?6 with an average value of 14.38×10?6. Yet, the indium content inthe Gaofeng deposit is higher than that in the Dafulou and Tongkeng deposit, showing a particularly significant supernormalenrichment. Besides, the cadmium content in pyrite is also higher than other dispersed elements, and similarly the abnormalenrichment of cadmium in the Gaofeng deposit is also very significant. An obvious positive correlation exists between In and Cd, orTl, but a negative correlation between In and Re. It is difficult to find out a positive or negative correlation between In and Ga. Theelement zinc is of great importance to the enrichment of indium, which can possibly facilitate to the migration and crystallization of dispersed element indium.

Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions

The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging.In this study,acidic poly(ionic liquid)s with swelling ability(SAPILs)were designed and synthesized via the free radical copolymerization of ionic liquid monomers,sodium p-styrenesulfonate,and crosslinkers,followed by acidification.The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength.The thermogravimetric analysis results in the temperature range of 300–345°C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H)(245°C).Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional(3D)honeycomb structure in water,which was ascribed to the swelling-induced self-assembly of the molecules.Moreover,we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol,and determined that their catalytic activity was much higher than that of homogeneous acid catalysts.The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures.Depending on the reaction mixture,the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it,which suggested the high enrichment ability of SAPILs for cyclohexyl acetate.The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate,which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.