超疏水三聚氰胺海绵粉末的制备及破乳性能

通过氯化铝溶液和甲基三氯硅烷溶液两步浸泡法制备了一种超疏水三聚氰胺海绵粉末,并对改性样品进行了扫描电镜、红外光谱和X射线光电子能谱分析。从微观结构和化学组成两方面共同揭示了粗糙度增加、硅烷化以及金属离子配位三者协同作用的超疏水转变机理。验证了压实的改性三聚氰胺粉末作为过滤材料用于“油包水”乳液高效分离的性能,讨论了润湿性、压实程度、初始含水率及粒径大小对于海绵粉末破乳性能的影响,发现适当提高材料疏水性、粉末压实程度,降低乳液初始含水率、减小粉末粒径可以有效改善其破乳效率。

Feasibility Study of the GST‑SVD in Extracting the Fault Feature of Rolling Bearing under Variable Conditions

Feature information extraction is one of the key steps in prognostics and health management of rotating machinery.In the present study,an investigation about the feasibility of a methodology based on generalized S transform(GST)and singular value decomposition(SVD)methods for feature extraction in rolling bearing,due to local damage under variable conditions,is conducted.The technique adopts the GST method,following the time-frequency analysis,to transform a raw fault signal of the rolling bearing into a two-dimensional complex matrix.And then,the SVD method is performed to decompose the matrix to obtain the feature vectors.By this procedure it is possible to obtain the fault feature information of rolling bearing under different speeds and different loads.In order to streamline the feature parameters of the feature vectors to train more uncomplicated models,the principal component analysis(PCA)subsequently performed.The particle swarm optimization-support vector machine(PSO-SVM)model is used to identify and classify the different fault states of rolling bearing.Furthermore,in order to highlight the superiority of the proposed method some comparisons are conducted with the conventional methods.The obtained results show that the proposed method can effectively extract fault features of the rolling bearing under variable conditions.

Analysis on Composition and Content of Glucosinolates in Broccoli Flowers and Leaves

Glucosinolate composition and content were evaluated in flowers and leaves of 12 different broccoli varieties. The results indicated that there were 9 glucosinolates in broccoli,namely Glucoiberin(IBE); Progoitrin(PRO);Sinigrin(SIN);Glucoraphanin(RAA);Gluconapin(NAP);4-Hydroxyglucobrassicin(4OH);Glucobrassicin(GBC);4-Methoxyglucobrassicin(4ME);Neoglucobrassicin(NEO).Total glucosinolate content in flowers was 1-5 times higher than in leaves. The predominant glucosinolate in broccoli was glucoraphanin.

Glucosinolate Variation in Turnip (Brassica rapa L.) at Different Growing Stages

The seed, leaf and root parts of three turnip （ Brassica rapa L.） cultivars were analyzed for glucosinolates. The component and concentration of glucosinolates in the three cultivars were also analyzed at different growing stages. Eight kinds of glucosinolates were tested in turnip. They were PRO, NAP, 4OH, GBN, GBC, NAS, 4ME and NEO, respectively. The contents and kinds of glucosinolates varied at different growing stages. The content of NAS was the highest in the seed, GBC and NEO contents were the highest in the seedling, GBN and NEO contents were the highest in the leaf, while the highest NAS content was in the root.

Double-ended passivator enables dark-current-suppressed colloidal quantum dot photodiodes for CMOS-integrated infrared imagers

Lead sulfide(PbS)colloidal quantum dot(CQD)photodiodes integrated with silicon-based readout integrated circuits(ROICs)offer a promising solution for the next-generation short-wave infrared(SWIR)imaging technology.Despite their potential,large-size CQD photodiodes pose a challenge due to high dark currents resulting from surface states on nonpassivated(100)facets and trap states generated by CQD fusion.In this work,we present a novel approach to address this issue by introducing double-ended ligands that supplementally passivate(100)facets of halidecapped large-size CQDs,leading to suppressed bandtail states and reduced defect concentration.Our results demonstrate that the dark current density is highly suppressed by about an order of magnitude to 9.6 nA cm^(2) at -10 mV,which is among the lowest reported for PbS CQD photodiodes.Furthermore,the performance of the photodiodes is exemplary,yielding an external quantum efficiency of 50.8%(which corresponds to a responsivity of 0.532 A W^(-1))and a specific detectivity of 2.5×10^(12) Jones at 1300 nm.By integrating CQD photodiodes with CMOS ROICs,the CQD imager provides high-resolution(640×512)SWIR imaging for infrared penetration and material discrimination.

表面活性剂驱油机理研究新进展:胶束增溶和原位乳化

降低油/水界面张力被认为是表面活性剂提高原油采收率的主要机理,但部分现场试验表明,低浓度表面活性剂驱在未达到超低界面张力的情况下也可以提高采收率,多孔介质中表面活性剂溶液与原油逐步接触后的演化过程尚无研究.针对这些问题,我们从微米和纳米尺度上深入剖析了表面活性剂驱油机理,提出了“胶束增溶,乳化携油”的新认识.通过吸光度测试、小角度中子散射和透射电子显微镜等方法评价了表面活性剂溶液与油的相互作用,发现表面活性剂胶束可通过增溶部分原油的方式提高采收率;利用微流控技术研究了表面活性剂驱油过程中的乳化过程,发现原位乳化主要通过封堵大孔道和乳化携油提高采收率.相关研究结果有助于深入理解表面活性剂溶液与原油间的相互作用,为生产实践中的配方优化提供理论依据.

On the Kernel of the Borel’s Characteristic Map of Lie Groups

For compact and connected Lie group G with a maximal torus T the quotient space G/T is canonically a smooth projective manifold,known as the complete flag manifold of the group G.The cohomology ring map c^(∗):H^(∗)(B T)→H∗(G/T)induced by the inclusion c:G/T→B_(T) is called the Borel’s characteristic map of the group G[7,8],where B T denotes the classifying space of T.Let G be simply-connected and simple.Based on the Schubert presentation of the cohomology H^(∗)(G/T)of the flag manifold G/T obtained in[10,11],we develop a method to find a basic set of explicit generators for the kernel ker c^(∗)⊂H^(∗)(B_(T))of the characteristic map c.

舒伯特计数演算的严格基础

希尔伯特(Hilbert)第15问题要求,为舒伯特(Schubert)计数演算法建立严格基础.其中,长期悬而未解的部分是舒伯特特征数问题.在构建代数几何学的工作中,范·德·瓦尔登(van der Waerden)和韦伊(Weil)将经典的舒伯特演算归结于决定旗流形相交理论的问题.本文介绍第15问题的背景、内容以及解答历程.本文的重点是计算特征数的统一公式(定理5.1)以及解答韦伊问题的系统表述(定理5.2).本文通过应用示例5.1和5.2,说明该公式和算法的有效性.

A forcing relation of braids from Nielsen fixed point theory

In this paper, we focus our attention on the connections between the braid group and Nielsen fixed point theory. A new forcing relation between braids is introduced, and we show that it can be fulfilled by using Nielsen fixed point theory.

Difference Cochains and Reidemeister Traces

The authors consider the difference of Reidemeister traces and difference cochain of given two self-maps, and find out a relation involving these two invariants.As an application, an inductive formula of the Reidemeister traces for self-maps on a kind of CW-complex, including spherical manifolds is obtained.