Synthesis,characterization, and applications of organic-inorganic hybrid mesoporous silica

Organic-inorganic hybrid mesoporous materials composed of homogeneously distributed ethane group in a silica framework were prepared by using 1,2 bis(trimethoxysilyl) ethane (BTME) as a precursor and alkyltrimethylammoniumchloride or -bromide surfactant as a structure directing agent with or without the presence of a swelling agent, mesitylene. Characterization of the materials was performed by XRD, TEM/SEM,^29Si-/^13C-solid state NMR, and N₂-adsorption. Testing of the hybrid material as a reversed phase HPLC column stationary phase after C18 surfacefunctionalization demonstrated a promising result, which closely approaches the performance of a commercial product. Mn-salen complex tethering on the hybrid material produced a catalyst with somewhat enhanced performance in liquid phase etherification with tert-butyl hydroperoxide as oxidant. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

MTP: discovering high quality partitions in real world graphs

Given a real world graph, how can we find a large subgraph whose partition quality is much better than the original? How can we use a partition of that subgraph to discover a high quality global partition? Although graph partitioning especially with balanced sizes has received attentions in various applications, it is known NP-hard, and also known that there is no good cut at a large scale for real graphs. In this paper, we propose a novel approach for graph partitioning. Our first focus is on finding a large subgraph with high quality partitions, in terms of conductance. Despite the difficulty of the task for the whole graph, we observe that there is a large connected subgraph whose partition quality is much better than the original. Our proposed method MTP finds such a subgraph by removing “hub” nodes with large degrees, and taking the remaining giant connected component. Further, we extend MTP to gb MTP (Global Balanced MTP) for discovering a global balanced partition. gb MTP attaches the excluded nodes in MTP to the partition found by MTP in a greedy way. In experiments, we demonstrate that MTP finds a subgraph of a large size with low conductance graph partitions, compared with competing methods. We also show that the competitors cannot find connected subgraphs while our method does, by construction. This improvement in partition quality for the subgraph is especially noticeable for large scale cuts—for a balanced partition, down to 14 % of the original conductance with the subgraph size 70 % of the total. As a result, the found subgraph has clear partitions at almost all scales compared with the original. Moreover, gb MTP generally discovers global balanced partitions whose conductance are lower than those found by METIS, the state-of-the-art graph partitioning method.     

Determination of 66 pesticide residues in livestock products using QuEChERS and GC–MS/MS

Food Science and Biotechnology - Determinations of 66 pesticide residues in different matrices including beef, pork, chicken, eggs, and milk were conducted using GC–MS/MS combined with the...