Co-reaction of Ethene and Methylation Agents over SAPO-34 and ZSM-22

Co-reaction of ethene and different methylation agents (i.e. methanol and chloromethane) was carried out over SAPO-34 and ZSM-22 and the results are compared. It was found that the enhancement of ethene conversion was achieved by co-feeding it with methylation agents. In the ethene–chloromethane system, the methylation of ethene by chloromethane was more prominent compared with that of the co-reaction of ethene and methanol. The reasons for the differences between ethene–methanol and ethene–chloromethane co-reaction system are discussed. Complete suppress of direct conversion of methanol or ethene could be achieved over ZSM-22 by pre-coking, and propene selectivity higher than 80% was obtained at lower conversions.     

有机阳离子转运体基因多态性与奥沙利铂毒性及疗效的相关性研究

目的：探讨有机阳离子转运体1的编码基因SLC22A1的SNP位点rs628031、rs650284、rs683369基因多态性与奥沙利铂毒性及临床疗效之间的相关性。方法：选取2018年1月至6月在北京大学深圳医院肿瘤科住院的72例结直肠癌患者,收集患者外周静脉血并提取DNA样本,利用SNaPshot SNP分型技术确定研究位点的基因型并分析。根据常见不良事件评价标准（CTCAE5.0版）评估奥沙利铂的胃肠道毒性、血液毒性以及神经毒性;根据实体瘤的疗效评价标准（RECIST 1.1）评估患者的化疗疗效,结合患者其他临床资料进行统计分析。结果：卡方检验结果显示SLC22A1基因位点rs628031和rs683369的多态性可能与奥沙利铂的化疗毒性及疗效相关。与rs628031 GG基因型相比,携带GA或AA基因型的患者3级恶心呕吐发生率更低（P=0.017）,同时疗效反应性也可能更差（P=0.008）;与rs683369 CC基因型相比,携带GC或GG基因型的患者3级恶心呕吐发生率更低（P=0.002）,同时疗效反应性也可能更差（P=0.014）。结论：SLC22A1的基因多态性与奥沙利铂的毒性及疗效之间存在相关性,可能为接受奥沙利铂治疗的结直肠癌患者的个体化方案调整及预后判断带来帮助。     

加热温度对Al-Si涂层热成形钢组织及性能的影响

利用粗糙度仪、扫描电镜、硬度计、辉光放电原子发射光谱仪等检测方法,研究分析了热冲压成形工艺过程中的加热温度对Al-Si涂层22MnB5热成形钢组织及性能的影响。结果表明,随着加热温度的升高,Fe沿垂直于表面方向由热成形钢基体向Al-Si涂层表面的迁移量逐渐增大,O沿垂直于表面方向由Al-Si涂层表面向热成形钢基体的迁移量逐渐增大,且迁移的最大深度约为2.80 μm。Fe沿垂直于表面方向由热成形钢基体向Al-Si涂层表面的迁移量直接决定了Fe-Al-Si相的形态、生成位置及界面结合层厚度。随着加热温度的升高,Al-Si涂层表面粗糙度R_a、峰值计数R_pc值先增大后减小;当加热温度为930 ℃时,涂层表面粗糙度R_a达到最大值1.89 μm,峰值计数R_pc值达到最大值218。随着加热温度的升高,Al-Si涂层总厚度从27.78 μm增加至40.46 μm,界面结合层厚度从1.08 μm增加至15.11 μm。当加热温度为930 ℃时,热成形钢基体的硬度达到最大值505 HV0.2。     

A sequential procedure to determine the number of breaks in trend with an integrated or stationary noise component

Perron and Yabu (2009a) consider the problem of testing for a break occurring at an unknown date in the trend function of a univariate time series when the noise component can be either stationary or integrated. This article extends their work by proposing a sequential test that allows one to test the null hypothesis of, say, l breaks versus the alternative hypothesis of (l + 1) breaks. The test enables consistent estimation of the number of breaks. In both stationary and integrated cases, it is shown that asymptotic critical values can be obtained from the relevant quantiles of the limit distribution of the test for a single break. Monte Carlo simulations suggest that the procedure works well in finite samples.     

Testing for nonlinear deterministic components when the order of integration is unknown

We consider testing for the presence of nonlinearities in the deterministic component of a time series, approximating the potential nonlinear behaviour using a Fourier function expansion. In contrast to procedures that are currently available, we develop tests that are robust to the order of integration, in the sense that they are asymptotically correctly sized regardless of whether the stochastic component of the series is stationary or contains a unit root. The tests we propose take the form of Wald statistics based on cumulated series, together with a correction factor to line up the asymptotic critical values across the I(0) and I(1) environments. The local asymptotic power and finite sample properties of the tests are evaluated using various different correction factors. We envisage that the testing procedure we recommend should be very useful to applied researchers wishing to draw robust inference regarding the presence of nonlinear deterministic components in a series.     

HMCM-22沸石分子筛催化合成缩醛(酮)

研究了在HMCM-22沸石分子筛催化下乙二醇与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、异戊醛、正辛醛、苯甲醛等多种醛（酮）的缩合反应。重点研究了乙二醇与环己酮的反应条件,考察了反应时间、醛（酮）与醇的配比、HMCM-22沸石的用量及催化剂重复使用等因素对反应的影响,优化了反应条件。结果表明,在醛（酮）与乙二醇物质的量比为1：1．2、催化剂用量为2g／mol醛（酮）、反应2h的条件下,转化率可达90％以上,选择性可达99％以上。表明HMCM-22沸石分子筛对该缩合反应有较好的催化活性和选择性。     

Assessing Persistence In Discrete Nonstationary Time‐Series Models

Abstract. The aim of this paper is to examine the application of measures of persistence in a range of time‐series models nested in the framework of Cramer (1961) . This framework is a generalization of the Wold (1938) decomposition for stationary time‐series which, in addition to accommodating the standard I(0) and I(1) models, caters for a broad range of alternative processes. Two measures of persistence are considered in some detail, namely the long‐run impulse‐response and variance‐ratio functions. Particular emphasis is given to the behaviour of these measures in a range of non‐stationary models specified in discrete time. We document the conflict that arises between different measures, applied to the same model, as well as conflict arising from the use of a given measure in different models. Precisely which persistence measures are time dependent and which are not, is highlighted. The nature of the general representation used also helps to clarify which shock the impulse‐response function refers to in the case of models where more than one random disturbance impinges on the time series.     

Forecasting linear dynamical systems using subspace methods

This article presents a novel approach to predict with subspace methods. It consists in combining multiple forecasts obtained from setting a range of values for a specific parameter that is typically fixed by the user in this literature. Two procedures are proposed. The first one combines all the forecast in a particular range. The second one predicts with a restricted number of combinations previously optimized. Both methods are evaluated using Monte Carlo experiments and by forecasting the German gross domestic product.     

Stable and Selective Dehydrocondensation of Methane Towards Benzene on Modified Mo/HMCM-22 Catalyst by the Dealumination Treatment

A modified Mo/HMCM-22 catalyst by the dealumination treatment (Mo/HMCM-22-D) exhibited remarkable performance for the catalytic dehydrocondensation of methane with a higher selectivity of benzene and a lower selectivity of coke, in comparison with the same Mo catalyst supported on parent HMCM-22 (Mo/HMCM-22). Excellent catalytic stability as well as a high benzene formation rate of 1500 nmol/(g-cat·s) was obtained on a 6%Mo/HMCM-22-D catalyst at 1023 K, 3 atm and 2700 ml/(g·h) owing to the efficient suppression of coke formation. Dealumination of the HMCM-22 zeolite was characterized by XRD, ²⁷Al and ¹H MAS NMR and NH₃-TPD techniques. It was found that the dealumination treatment of HMCM-22 zeolite resulted in an effective suppression of acid sites, particularly the Brønsted acid sites (proton form in Al--O--Si) owing to the removal of tetrahedral framework aluminum, while the microporous structure and the zeolite framework remained unchanged. It was suggested that the stable and selective dehydrocondensation of methane towards benzene is based on the suppression of coke formation owing to the effective decrease of strong Brønsted acid sites by the dealumination treatment of the HMCM-22 zeolite.     

Biotransformation of l‐menthol by soil‐borne plant pathogenic fungi (Rhizoctonia solani)

The biotransformation of l‐menthol was investigated by using nine isolates of Rhizoctonia solani (AG‐1‐IA Rs24, Joichi‐2, RRG97‐1; AG‐1‐IB TR22, R147, 110.4; AG‐1‐IC F‐1, F‐4 and P‐1) as a biocatalyst. In the cases of Rhizoctonia solani F‐1, F‐4 and P‐1, almost all of the substrate was consumed in 3 days and the major metabolite increased rapidly for the first of 3 days incubation. The structure of the major metabolite was elucidated on the basis of its spectral data. The major metabolite was determined to be (?)‐(1S,3R,4S,6S)‐6‐hydroxymenthol which indicated that l‐menthol was hydroxylated at the C‐6 position. From the main component analysis, the nine isolates of Rhizoctonia solani were divided into two groups based on their ability to transform l‐menthol to (?)‐(1S,3R,4S,6S)‐6‐hydroxymenthol. This is the first report on the biotransformation of l‐menthol by Rhizoctonia solani. © 2001 Society of Chemical Industry