Easy separation and reutilization of the Jacobsen's catalyst in olefin oxidation

A new method for recycling the Jacobsen's catalyst used for the catalytic oxidation of R-(+)-limonene and cis-ethyl cinnamate at room temperature by in situ generated dimethyldioxirane (DMD) as oxidizing agent is presented. Neither the immobilization of the catalyst to the solid support nor modification of its chemical structure is involved in this method. Therefore, the excellent catalytic properties of the Jacobsen's catalyst could be retained. Limonene diepoxide was the main product of the oxidation of R-(+)-limonene, whereas a single epoxide with good enanantioselectivity (78% ee) was obtained in the asymmetric oxidation of cis-ethyl cinnamate. On the other hand, R-(+)-limonene showed to be more reactive than cis-ethyl cinnamate. In both cases, the catalyst was recovered and recycled without appreciable loss of its initial catalytic activity.     

形成倒装芯片焊点的铜接线柱焊凸(SBC)法

在倒装芯片应用中生长晶圆焊凸的工艺中对于间距较小(即小于150μm)、具有数个尺寸为150μm的焊凸,倒装前的焊锡涂敷好坏对产品的良率和可靠性起着重要作用。因为,如果涂敷的焊锡体积不均匀,就经不起涂敷过程中为确保涂敷在引线框上焊锡的完整和体积一致性而引入的强制视像系统检查,从而降低产出率。这就是一些组装工艺正设法减少或取消这些限制的原因。另一方面,采用直接熔化焊凸的方法来形成焊点是一种速度较快的工艺,但在保证回流处理后的离板高度方面有缺点,导致在温度和功率循环测试中的表现较差。介绍的采用铜接线柱焊凸(SolderBumponCopperStud;SBC)法解决了这些问题;对于那些需要倒装的组装工艺而言,这是可保障其制造性较佳的解决方案。介绍采用铜接线柱焊凸(SBC)工艺在附着在倒装芯片上的金属基片和焊凸之间形成焊点的新方法,利用铜接线柱焊凸技术再配合晶圆级的焊锡丝印工艺在半导体上预先形成焊凸。这是替代电镀焊凸工艺一种别具成本效益的方法。     

Photonucleophilic Addition of the ε‐Amino Group of Lysine to a Triflusal Metabolite as a Mechanistic Key to Photoallergy Mediated by the Parent Drug

A mechanism for triflusal‐induced photoallergy involving complexation of 2‐hydroxy‐4‐trifluoromethylbenzoic acid with site I of human serum albumin and subsequent formation of a covalent adduct by photoreaction between a metabolite and a neighboring lysine residue is proposed. This is supported by the observed photobinding to poly‐L ‐lysine. Thereby, a photoantigen is generated, which is a likely trigger of the immune response.

     

Local optimal scale in a hierarchical segmentation method for satellite images

Over recent decades, remote sensing has emerged as an effective tool for improving agriculture productivity. In particular, many works have dealt with the problem of identifying characteristics or phenomena of crops and orchards on different scales using remote sensed images. Since the natural processes are scale dependent and most of them are hierarchically structured, the determination of optimal study scales is mandatory in understanding these processes and their interactions. The concept of multi-scale/multi-resolution inherent to OBIA methodologies allows the scale problem to be dealt with. But for that multi-scale and hierarchical segmentation algorithms are required. The question that remains unsolved is to determine the suitable scale segmentation that allows different objects and phenomena to be characterized in a single image. In this work, an adaptation of the Simple Linear Iterative Clustering (SLIC) algorithm to perform a multi-scale hierarchical segmentation of satellite images is proposed. The selection of the optimal multi-scale segmentation for different regions of the image is carried out by evaluating the intra-variability and inter-heterogeneity of the regions obtained on each scale with respect to the parent-regions defined by the coarsest scale. To achieve this goal, an objective function, that combines weighted variance and the global Moran index, has been used. Two different kinds of experiment have been carried out, generating the number of regions on each scale through linear and dyadic approaches. This methodology has allowed, on the one hand, the detection of objects on different scales and, on the other hand, to represent them all in a single image. Altogether, the procedure provides the user with a better comprehension of the land cover, the objects on it and the phenomena occurring.     

Microwave assisted extraction combined with dispersive liquid–liquid microextraction as a sensitive sample preparation method for the determination of haloanisoles and halophenols in cork stoppers and oak barrel sawdust

In this paper, a method based on microwave assisted extraction (MAE) in combination with dispersive liquid–liquid microextraction (DLLME) has been proposed as a new approach for the sensitive determination of cork taint responsible compounds in cork stoppers and oak barrel sawdust. For this purpose, haloanisoles and halophenols were extracted from the solid samples using a MAE method. Subsequently, a DLLME-derivatisation procedure was applied on the MAE extracts and the analytes were determined by gas chromatography–electron capture detection (GC–ECD). Parameters affecting the DLLME-derivatisation method were exhaustively investigated by means of experimental design methodology. Once optimised, the proposed method showed satisfactory linearity (correlation coefficients over 0.991), repeatability (below 10.4%) and inter-day precision (below 11.2%). Detection limits obtained were similar or even lower than previously reported. The results obtained proved the suitability of the combination of MAE with DLLME as a sensitive sample preparation methodology for the analysis of haloanisoles and halophenols in solid enological matrices.