Defect‐Controlled Preparation of UiO‐66 Metal–Organic Framework Thin Films with Molecular Sieving Capability

Metal–organic framework (MOF) UiO‐66 thin films are solvothermally grown on conducting substrates. The as‐synthesized MOF thin films are subsequently dried by a supercritical process or treated with polydimethylsiloxane (PDMS). The obtained UiO‐66 thin films show excellent molecular sieving capability as confirmed by the electrochemical studies for redox‐active species with different sizes.     

PowerSlicing to determine fluorescence lifetimes of water-soluble organic matter derived from soils,plant biomass,and animal manures

Time-resolved fluorescence spectroscopy was used to characterize water-soluble organic matter (WSOM) which plays an important role in soil ecosystem processes. WSOM was extracted from plant biomass, animal manures, and soils from controlled cropping systems studies with known histories of organic amendments. Lifetime constants were derived using the multi-way PowerSlicing method which provides a non-iterative, multi-exponential fitting of decay profiles. The lifetimes obtained by PowerSlicing were not significantly different from those obtained using the traditional discrete components analysis. The three components attributed to WSOM had lifetimes of 0.38 ± 0.14, 2.11 ± 0.72, and 7.08 ± 1.18 ns which are in agreement with previous lifetimes reported for humic substances. This study provides further support for the new paradigm for the structure of soil organic matter where the organic matter is composed of low-molecular-weight components held together by hydrogen bonding and hydrophobic interactions.     

Evaluation of Formaldehyde in Foundry Waste Sands Using Liquid Chromatography

Abstract

The industrial manufacturing of metallic objects results in a high level of foundry waste sands that may contain toxic compounds such as formaldehyde. The formaldehyde content of foundry waste sands was evaluated by liquid chromatography. Samples were collected during various steps of the industrial processes. Results showed that the phenolic alkaline process generated waste sands with higher formaldehyde content than the furanic process; the highest value was 7.6 × 10^?3% (w/w). In this work, formaldehyde content decreased with time in all of the samples studied, revealing that most formaldehyde was released to the occupational environment.     

Syntheses and molecular structures of four inorganic–organic hybrid compounds from N-containing aromatic bases and perchlorometallates of Zn,Cu, Sn,and Fe

Four organic–inorganic crystals, [(HL1)₂(ZnCl₄)]·H₂O (1) (L1?=?2-methylquinoline), [(HL1)₂(CuCl₄)] (2), [(HL2)₂SnCl₆] (3) (L2?=?6-bromobenzo[d]thiazol-2-amine), and [(HL3)FeCl₄] (4) (L3?=?5,7-dimethyl-1,8-naphthyridine-2-amine), derived from N-containing aromatic Brønsted bases and metal(II) chlorides (zinc(II) chloride, copper(II) chloride dihydrate, tin(II) chloride dihydrate, and iron(III) chloride hexahydrate) were prepared at room temperature and characterized by IR, X-ray structure analysis, elemental analysis, and TG analysis. The crystals are built up by perchlorometallates (Zn, Cu, Sn, and Fe) associated with organic cations through multiple non-covalent associations. X-ray diffraction analysis reveals that 1 and 2 have 3-D network structures built from hydrogen bonds between the cations and chlorometallates. Water molecules play an important role in structure extension in 1. Anhydrous 3 and 4 produced from 2-aminoheterocyclic derivatives display 2-D sheet structures. Arrangements of anions and cations are dominated by shape and size of cations, and also by the different structures of the chlorometallates as well as non-bonding interactions in the crystal structures. Except for 1, the other compounds are thermally stable below 240°C.     

中德化学启蒙教材有机内容比较

就化学启蒙教育阶段有机化学教学内容,将德国的《今日化学SⅠ》、国内的沪教版、人教版、鲁教版4套教材,从知识内容的选取、组织呈现等角度进行了比较,并在实验设计、作业设计、拓展学习3方面向教材编写和教学实践提出了建议。     

Aerosol observation in Fengtai area, Beijing

Measurements of aerosol number concentration and particulate matter with diameter less than 10μm (PM10) mass concentrations of urban background aerosols were performed in Fengtai area, Beijing in 2006. Black carbon (BC) was collected simultaneously from the ground and analyzed to determine the particulate matter components. To satisfy the interest in continuous monitoring of temporal and spatial distribution of aerosols, the relationship between extinction coefficient (visibility) measured by lidar remote sensing and the aerosol number concentration measured from the ground was derived by using statistical method. Vertical particle number concentration profile within the planetary boundary layer could be inversed through the lidar data as well as the statistical relation.