对氯苯酚超临界水脱氯的反应动力学及机理分析

在反应温度400~460℃、压力24MPa、停留时间30~200s,过氧量100%~500%的条件下,分析了对氯苯酚（4-CP）在等温立式柱塞流反应器中的超临界水氧化脱氯反应动力学及机理。首先得出温度为440℃、压力为24MPa、过氧量375%时,4-CP脱氯率可以达到80%的反应效果;过程显示,随着停留时间增大、温度提高,4-CP脱氯率提高,4-CP初始质量浓度和过氧量变化对过程无显著影响;动力学研究发现,4-CP的超临界水氧化技术（SCWO）反应动力学过程符合幂指数方程,通过参数拟合,求得4-CP反应级数为1,H2O2的反应级数为零,反应活化能为92.978KJ·mol-1,指前因子为104.6302,动力学方程能较好地预测实验结果;最后,通过GC/MS方法定性分析的反应中间产物为对苯二酚、邻苯二酚和对苯醌等,推测反应过程中伴随自由基参加的偶合反应占主导。研究结果证明了4-CP的超临界水氧化脱氯过程可行与高效,可望成为工艺应用的基础。

基于改进SCW的道路标志牌字符定位算法

本文提出了一种快速的基于改进SCW的道路标志牌字符定位算法。首先采用改进的自适应图像分割方法SCW对输入图像进行分割,然后对所得二值图像进行连通区域分析,获得斑块信息。最后根据一系列判决标准得出道路标志牌上字符的最终位置。实验结果显示该算法具有很强的准确性和鲁棒性。

一株蚕丝脱胶酶产生菌的筛选鉴定及产酶条件优化试验

从丝厂周边土壤中筛选到一株能高效生产脱胶酶的菌株。通过形态学观察和16S rDNA碱基序列测定及同源性分析,鉴定该菌株为革兰阳性杆状细菌,有芽孢,好氧且不具运动性,属于芽孢杆菌属(Bacillus)。对scw2-1菌株产脱胶酶发酵条件的优化结果是:培养基组分的最佳碳源为0.03 g/mL可溶性淀粉、氮源为0.03 g/mL大豆粉、金属离子为K+(0.01 g/mL KHPO),发酵最适温度为37℃,培养基初始pH值为10.0,发酵时间为72 h。

雄先型核桃雄花疏除的二次回归与BP神经网络模型研究（英文）

雄先型核桃雄花疏除(去雄)是提高产量的重要管理措施,为提高核桃去雄的效率,建立二次回归与BP神经网络模型。分别以乙烯利、赤霉素和甲哌鎓为自变量和核桃雄花脱落率为响应指标,进行田间建模试验,建立了二次多项式回归方程和BP神经网络模型,并于翌年进行BP模型田间确认试验。试验数据分为训练集、确认集和试验集,中心组合(二次旋转回归试验设计)田间建模试验得到的20组数据随机划为训练集(17)和确认集(3)数据,试验集为翌年田间确认试验得到的数据,BP神经网络的拓扑结构为3-5-1。1BP神经网络对确认集样本的预测值误差分别为1.3550%、0.4291%、0.3538%;2BP神经网络的预测值与田间确认试验结果相差为2.04%,回归预测值与田间确认试验结果相差为3.12%;3BP神经网络预测比回归预测提高预测精度1.0%以上。将二次多项式逐步回归分析和BP神经网络方法有效的结合使用,既可明确各因子的作用效应亦可得到相对准确的预测结果。

科技档案管理系统设计

介绍了科技档案管理系统的设计思路,并对使用LAMP网站框架搭建档案管理系统过程中的关键技术(如中文分词技术)等进行了相关的描述。

超临界水中渣油加氢转化的生焦行为及焦炭形貌

采用高压反应釜进行渣油加氢转化实验,通过加入超临界水(SCW),考察焦炭产率的变化。结果表明,添加少量的SCW,其物理方面的分散作用和溶解作用会降低体系的生焦量。增加SCW的添加量,水分子阻碍了加氢反应的发生,生焦量开始增加;继续增大SCW的添加量,大量水分子形成的"笼效应"抑制了重组分的聚集缩合,焦炭产率又开始降低。对比有无添加SCW条件下生焦颗粒的形貌,发现添加SCW条件下,焦炭颗粒具有明显的层状结构,颗粒整体性较差,是由于焦炭颗粒形成过程中存在水分子的阻碍作用。

Physiological Studies on Ratoonability of Sugarcane Varieties under Tropical Indian Condition

The ratoon crop occupies approximately 40% of the total area of sugarcane crop in tropical India. The main reason for the lower average cane productivity is the yield decline in ratoon crops (40 - 50 t/ha) despite the release of the high yielding varieties and advanced cane production technology. The physiological factors associated with ratooning performance and the variation in growth and yield were studied in 11 sugarcane varieties in two cycles of one plant and two ratoon crops each. The first ratoon and second ratoon crop showed 17.0% and 28.1% reduction in tiller production and 15.5% and 15.7% reduction in NMC, respectively, over plant crop. The differences in growth parameters between the plant and ratoon crops at the formative phase were lesser than that of grand growth and maturity phases. Varieties Co 86032, Co 97008, Co 95020 Co 99004 and Co 2000-10 showed better physiological efficiency in terms of plant height, shoot population, leaf size, TDMP, partitioning efficiency, chlorophyll content and nitrate reductase activity and significantly higher yield components such as NMC, SCW, cane length, internodal length as well as cane yield compared to other varieties. The higher reduction in ratoon yield in Co 99008, Co 94012, Co 8021 and Co 97009 (>35.00% reduction) was due to higher reduction in tiller production associated with stunted plant growth and root system, reducetion in individual leaf size and LAI, TDMP, total chlorophyll content, NMC, internodal length and SCW. The results obtained indicated that the plant height, TDMP, stem partitioning, leaf size, total chlorophyll content, SCW, cane length and cane girth were highly associated with yield of first and second ratoon crops than that of plant crop. Therefore the difference in the association between physiological parameters with yield of plant and ratoon crops therefore decides the ratooning potential of the crop.

页岩气水平井固井技术难点分析与对策

页岩气开发具有开采寿命长和生产周期长的优点——大部分产气页岩分布范围广、厚度大,且普遍含气,使得页岩气井能够长期地稳定产气,包括页岩气在内的非常规能源越来越受到重视。本文针对页岩气固井技术难点:水泥石力学性能难以满足要求,第二界面封固质量差,水平段套管居中度差,影响顶替效率。通过实验,研究出采用SP-1/SP-2水泥浆体系,适用于经常面临交变应力的场合和频繁大规模压裂的页岩气井,研究开发了SCW型洗油冲洗液,并对冲洗液的洗油效果进行了评价,通过优选合适的扶正器,并借助漂浮接箍提高套管井内居中度,有助于套管顺利下入。最后通过现场应用证明了本文研究成果切实有效,可以做相关推广。

Forming of Space Charge Wave with Broad Frequency Spectrum in Helical Relativistic Two-Stream Electron Beams

We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.

非线性分数阶Volterra积分-微分方程的SCW数值方法

推导第二类Chebyshev小波(SCW)分数阶算子矩阵,利用SCW算子矩阵方法求解了一类非线性分数阶Volterra积分-微分方程.此方法将分数阶积分-微分方程转化成非线性代数方程组求解,可以简化分数阶方程的求解,所得到的数值结果表明该方法是有效和精确的.

Effect of Surface Modification on Candidate Alloys for Canadian SCWR Fuel Cladding

The Canadian Generation-IV supercritical water reactor (SCWR) requires peak cladding surface temperature of 800℃ for a core outlet temperature of 625℃. Materials selection for high temperature fuel cladding is becoming one of the major challenging tasks. Austenitic stainless steels with excellent corrosion resistance are often susceptible to stress corrosion cracking upon SCW exposure. Low-Cr steels such as P91 exhibit good high-temperature mechanical properties, but the lack of sufficient Cr content makes this group of alloys corrode too fast. One possible solution is to use coatings or surface modification techniques to improve the surface resistance to corrosion. In this study, we investigated the effect of surface modification on commercial 316L stainless steel. Surface modification by mechanical deformation has marked improvement in corrosion resistance during SCW exposure. Possible mechanisms for such improvement are discussed.

SCW620铸钢与S460ML钢板的焊接性能研究

以某国外悬索桥主索鞍为例,通过焊接工艺评定及焊缝热影响区的CTOD试验,对SCW620铸钢与S460ML钢板异种材质焊接性能进行试验研究,为该类型的产品拟定正确的焊接工艺规程做好技术储备。

挖掘机斗杆铸件后支座开裂分析

通过对挖掘机斗杆铸件后支座故障件进行机械性能及组织形貌分析,从故障件硬度分布、拉伸试验状况结合其金相组织分析可知,热处理保温时间不足及淬火裂纹是导致铸件后支座开裂的根本原因。

某工程SCW钢板剪力墙施工技术

本文介绍了某超高层单片独立式SCW组合钢板剪力墙结构的钢板剪力墙施工技术及质量控制。详细阐述了针对SCW钢板剪力墙吊装与焊接施工进度迟缓,焊接后钢板与型钢端柱垂直度、平面扭曲变形严重等问题采取的有效措施,有效控制了施工质量。

Combining single-cell RNA sequencing with spatial transcriptome analysis reveals dynamic molecular maps of cambium differentiation in the primary and secondary growth of trees

Primary and secondary growth of the tree stem are responsible for corresponding increases in trunk height and diameter.However,our molecular understanding of the biological processes that underlie these two types of growth is incomplete.In this study,we used single-cell RNA sequencing and spatial transcriptome sequencing to reveal the transcriptional landscapes of primary and secondary growth tissues in the Populus stem.Comparison between the cell atlas and differentiation trajectory of primary and secondary growth revealed different regulatory networks involved in cell differentiation from cambium to xylem precursors and phloem precursors.These regulatory networks may be controlled by auxin accumulation and distribution.Analysis of cell differentiation trajectories suggested that vessel and fiber development followed a sequential pattern of progressive transcriptional regulation.This research provides new insights into the processes of cell identity and differentiation that occur throughout primary and secondary growth of tree stems,increasing our understanding of the cellular differentiation dynamics that occur during stemgrowth in trees.

Advances in Severe Convection Research and Operation in China

This article reviews the advances in severe convection research and operation in China during the past several decades.The favorable synoptic situations for severe convective weather(SCW),the major organization modes of severe convective storms(SCSs),the favorable environmental conditions and characteristics of weather radar echoes and satellite images of SCW and SCSs,and the forecasting and nowcasting techniques of SCW,are emphasized.As a whole,Chinese scientists have achieved a profound understanding of the synoptic patterns,organization,and evolution characteristics of SCW from radar and satellite observations,and the mechanisms of different types of convective weather in China.Specifically,in-depth understanding of the multiple types of convection triggers,along with the environmental conditions,structures and organization modes,and maintenance mechanisms of supercell storms and squall lines,has been obtained.The organization modes and climatological distributions of mesoscale convective systems and different types of SCW,and the multiscale characteristics and formation mechanisms of large hail,tornadoes,downbursts,and damaging convective wind gusts based on radar,satellite,and lightning observations,as well as the related features from damage surveys,are elucidated.In terms of operational applications,different types of identification and mesoanalysis techniques,and various forecasting and nowcasting techniques using methods such as the"ingredients-based"and deep learning algorithms,have been developed.As a result,the performance of operational SCW forecasts in China has been significantly improved.

Progress in Severe Convective Weather Forecasting in China since the 1950s

Located in the Asian monsoon region, China frequently experiences severe convective weather(SCW), such as short-duration heavy rainfall(SDHR), thunderstorm high winds, hails, and occasional tornadoes. Progress in SCW forecasting in China is closely related to the construction and development of meteorological observation networks,especially weather radar and meteorological satellite networks. In the late 1950 s, some county-level meteorological bureaus began to conduct empirical hail forecasting based on observations of clouds and surface meteorological variables. It took over half a century to develop a modern comprehensive operational monitoring and warning system for SCW forecast nationwide since the setup of the first weather radar in 1959. The operational SCW forecasting, including real-time monitoring, warnings valid for tens of minutes, watches valid for several hours, and outlooks covering lead times of up to three days, was established in 2009. Operational monitoring and forecasting of thunderstorms,SDHR, thunderstorm high winds, and hails have been carried out. The performance of operational SCW forecasting will be continually improved in the future with the development of convection-resolving numerical models(CRNMs), the upgrade of weather radar networks, the launch of new-generation meteorological satellites, better understanding of meso-γ and microscale SCW systems, and further application of artificial intelligence technology and CRNM predictions.

Molecular studies of cellulose synthase supercomplex from cotton fiber reveal its unique biochemical properties

Cotton fiber is a highly elongated and thickened single cell that produces large quantities of cellulose,which is synthesized and assembled into cell wall microfibrils by the cellulose synthase complex(CSC).In this study,we report that in cotton(Gossypium hirsutum)fibers harvested during secondary cell wall(SCW)synthesis,GhCesA 4,7,and 8 assembled into heteromers in a previously uncharacterized 36-mer-like cellulose synthase supercomplex(CSS).This super CSC was observed in samples prepared using cotton fiber cells harvested during the SCW synthesis period but not from cotton stem tissue or any samples obtained from Arabidopsis.Knock-out of any of GhCesA 4,7,and 8 resulted in the disappearance of the CSS and the production of fiber cells with no SCW thickening.Cotton fiber CSS showed significantly higher enzyme activity than samples prepared from knock-out cotton lines.We found that the microfibrils from the SCW of wild-type cotton fibers may contain 72 glucan chains in a bundle,unlike other plant materials studied.GhCesA4,7,and 8 restored both the dwarf and reduced vascular bundle phenotypes of their orthologous Arabidopsis mutants,potentially by reforming the CSC hexamers.Genetic complementation was not observed when non-orthologous CesA genes were used,indicating that each of the three subunits is indispensable for CSC formation and for full cellulose synthase function.Characterization of cotton CSS will increase our understanding of the regulation of SCW biosynthesis.

OsIDD2, a zinc finger and INDETERMINATE DOMAIN protein, regulates secondary cell wall formation

Previously, we found 123 transcription factors（TFs） as candidate regulators of secondary cell wall（SCW）formation in rice by using phylogenetic and co-expression network analyses. Among them, we examined in this work the role of OsIDD_2, a zinc finger and indeterminate domain（IDD） family TF. Its overexpressors showed dwarfism, fragile leaves, and decreased lignin content, which are typical phenotypes of plants defective in SCW formation, whereas its knockout plants showed slightly increased lignin content.The RNA-seq and quantitative reverse transcription polymerase chain reaction analyses confirmed that some lignin biosynthetic genes were downregulated in the OsIDD_2-overexpressing plants, and revealed the same case for other genes involved in cellulose synthesis and sucrose metabolism. The transient expression assay using rice protoplasts revealed that OsIDD_2 negatively regulates the transcription of genes involved in lignin biosynthesis, cinnamyl alcohol dehydrogenase 2 and 3（CAD_2 and 3）, and sucrose metabolism, sucrose synthase 5（SUS_5）, whereas an Alpha Screen assay, which can detect the interaction between TFs and their target DNA sequences, directly confirmed the interaction between OsIDD_2 and the target sequences located in the promoter regions of CAD_2 and CAD_3. Based on these observations, we conclude that OsIDD_2 is negatively involved in SCW formation and other biological events by downregulating its target genes.