Microwave-Assisted Synthesis of the Flexible Iron-based MIL-88B Metal–Organic Framework for Advanced Energetic Systems

The 3D metal–organic framework (MOF), MIL-88B, built from the trivalent metal ions and the ditopic 1,4-Benzene dicarboxylic acid linker (H₂BDC), distinguishes itself from the other MOFs for its flexibility and high thermal stability. MIL-88B was synthesized by a rapid microwave-assisted solvothermal method at high power (850 W). The iron-based MIL-88B [Fe₃.O.Cl.(O₂C–C₆H₄–CO₂)₃] exposed oxygen and iron content of 29% and 24%, respectively, which offers unique properties as an oxygen-rich catalyst for energetic systems. Upon dispersion in an organic solvent and integration into ammonium perchlorate (AP) (the universal oxidizer for energetic systems), the dispersion of the MOF particles into the AP energetic matrix was uniform (investigated via elemental mapping using an EDX detector). Therefore, MIL-88B(Fe) could probe AP decomposition with the exclusive formation of mono-dispersed Fe₂O₃ nanocatalyst during the AP decomposition. The evolved nanocatalyst can offer superior combustion characteristics. XRD pattern for the MIL-88B(Fe) framework TGA residuals confirmed the formation of α-Fe₂O₃ nanocatalyst as a final product. The catalytic efficiency of MIL-88B(Fe) on AP thermal behavior was assessed via DSC and TGA. AP solely demonstrated a decomposition enthalpy of 733 J g^?1, while AP/MIL-88B(Fe) showed a 66% higher decomposition enthalpy of 1218 J g^?1; the main exothermic decomposition temperature was decreased by 71 °C. Besides, MIL-88B(Fe) resulted in a decrease in AP decomposition activation energy by 23% and 25% using Kissinger and Kissinger–Akahira–Sunose (KAS) models, respectively.

     

A Toxoplasma gondii Oxopurine Transporter Binds Nucleobases and Nucleosides Using Different Binding Modes

Toxoplasma gondii is unable to synthesize purines de novo, instead salvages them from its environment, inside the host cell, for which they need high affinity carriers. Here, we report the expression of a T. gondii Equilibrative Nucleoside Transporter, Tg244440, in a Trypanosoma brucei strain from which nucleobase transporters have been deleted. Tg244440 transported hypoxanthine and guanine with similar affinity (K_m ~1 µM), while inosine and guanosine displayed K_i values of 4.05 and 3.30 µM, respectively. Low affinity was observed for adenosine, adenine, and pyrimidines, classifying Tg244440 as a high affinity oxopurine transporter. Purine analogues were used to probe the substrate-transporter binding interactions, culminating in quantitative models showing different binding modes for oxopurine bases, oxopurine nucleosides, and adenosine. Hypoxanthine and guanine interacted through protonated N1 and N9, and through unprotonated N3 and N7 of the purine ring, whereas inosine and guanosine mostly employed the ribose hydroxy groups for binding, in addition to N1H of the nucleobase. Conversely, the ribose moiety of adenosine barely made any contribution to binding. Tg244440 is the first gene identified to encode a high affinity oxopurine transporter in T. gondii and, to the best of our knowledge, the first purine transporter to employ different binding modes for nucleosides and nucleobases.     

Mineral Fillers in Intumescent Fire Retardant Formulations — Criteria for the Choice of a Natural Clay Filler for the Ammonium Polyphosphate/Pentaerythritol/Polypropylene System

Addition of natural clay materials in intumescent polypropylene-based formulations (additive: ammonium polyphosphate and pentaerythritol) leads either to a decrease or to an increase of their fire retardant performances versus the chemical or the physical characteristics of the clay materials. A study of the factors affecting these performances has been carried out using linear and principal components analysis. This analysis shows that the results of the evaluation tests (LOI and UL 94) are affected in different ways by the adduct of the different clay material and that an increase in the LOI is not necessarily related to an increase in the UL 94 classification. LOI values are improved by the presence of the montmorillonite and of illite clay minerals which may react with acidic phosphate to form active carbonization catelysts, in addition, the results of the LOI test are improved by the presence of quartz and other foreign minerals in the clay materials. This study discusses the part played by the different constitutive minerals in the formation of defects in the polymer chain during the mixing process. It is proposed that the presence of these defects leads to a change in fire retardant performance.     

Sustainable Oxidative Cleavage of Vegetable Oils into Diacids by Organo-Modified Molybdenum Oxide Heterogeneous Catalysts

Exploiting vegetable oils to produce industrially valuable diacids via an eco‐friendly process requires an efficient and recyclable catalyst. In this work, a novel catalytic system based on organo‐modified molybdenum trioxide was synthesized by a green hydrothermal method in one simple step, using Mo powder as precursor, hydrogen peroxide, and amphiphilic surfactants cetyltrimethylammonium bromide (CTAB) and tetramethylammonium bromide (TMAB) as capping agents. The synthesized materials were first characterized by different techniques including XRD, SEM, TGA, and FT‐IR. Interestingly, various morphologies were obtained depending on the nature of the surfactants and synthetic conditions. The synthesized catalysts were employed in oxidative cleavage of oleic acid, the most abundant unsaturated fatty acid, to produce azelaic and pelargonic acids with a benign oxidant, H₂O₂. Excellent catalytic activities resulting in full conversion of initial oleic acid were obtained, particularly for CTAB‐capped molybdenum oxide (CTAB/Mo molar ratio of 1:3) that gave 83 and 68% yields of production of azelaic and pelargonic acids, respectively. These are the highest yields that have been obtained for this reaction by heterogeneous catalysts up to now. Moreover, the CTAB‐capped catalyst could be conveniently separated from the reaction mixture by simple centrifugation and reused without significant loss of activity up to at least four cycles.     

Specific populations of the yeast Geotrichum candidum revealed by molecular typing

Geotrichum candidum is a ubiquitous yeast and an essential component in the production of many soft cheeses. We developed a multilocus sequence typing (MLST) scheme with five retained loci (NUP116, URA1, URA3, SAPT4 and PLB3) which were sufficiently divergent to distinguish 40 sequence types (STs) among the 67 G. candidum strains tested. Phylogenetic analyses defined five main clades; one clade was restricted to environmental isolates, three other clades included distinct environmental isolates and dairy strains, while the fifth clade comprised 34 strains (13 STs), among which all but two were isolated from milk, cheese or the dairy environment. These findings suggest an adaptation to the dairy ecosystems by a group of specialized European G. candidum strains. In addition, we developed a polymerase chain reaction inter‐long terminal repeat scheme, a fast and reproducible random amplification of polymorphic DNA‐like method for G. candidum, to type the closely related dairy strains, which could not be distinguished by MLST. Overall, our findings distinguished two types of dairy strains, one forming a homogeneous group with little genetic diversity, and the other more closely related to environmental isolates. Neither regional nor cheese specificity was observed in the dairy G. candidum strains analysed. This present study sheds light on the genetic diversity of both dairy and environmental strains of G. candidum and thus extends previous characterizations that have focused on the cheese isolates of this species. Copyright © 2016 John Wiley & Sons, Ltd.     

The effects of soaking of whole, dehulled and ground millet and soybean seeds on phytate degradation and Phy/Fe and Phy/Zn molar ratios

The degradation and leaching of phytates, phytase activity and iron and zinc concentrations have been studied after soaking of whole seeds, dehulled seeds and flours of millet and soybean, in order to investigate the efficiency of soaking on reducing Phy/Fe and Phy/Zn molar ratios. When using millet grains, dehulling and milling before soaking facilitated the leaching of phytates and phytases in the aqueous medium and hence phytate degradation. Dehulling of soybean seeds led to a marked increase in phytate content, whereas milling favoured reactions between phytases and phytates. The Phy/Fe and Phy/Zn molar ratios decreased only slightly during soaking. The highest decreases for millet were obtained after soaking of flour for 8 h (Phy/Fe: 10.8–7.7 and Phy/Zn: 20.3–15.1), and after soaking of whole seeds for 24 h for soybean (Phy/Fe: 10.4–9.4 and Phy/Zn: 23.8–19.1). Cooking of flours with water used for soaking did not increase phytate degradation.     

Agarose-based hydrogel as an electrografting cell

An agarose gel was used as an electrochemical cell to graft vinylic polymer layers on conductive surfaces by electro-initiated radical electrografting of various water-soluble and hydrophobic vinylic monomers in the presence of diazonium ions. The process was followed by in situ electrochemical measurements and the resulting grafted layer was characterized by infrared (IRRAS) and photoelectron (XPS) spectroscopy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

《可持续发展设计指南》选载(之六)如何利用新能源和系统来发展零能源建筑和周边环境

一、规划和设计生物气候型建筑■建筑工程项目的每一阶段都要尽量减少能量消耗设计生物气候型建筑的目的,就是要以产生尽可能少的能量消耗并充分考虑环境因素的条件在建筑物内部创造最大程度的舒适度。因此,在建筑工程项目的每一阶段内,都最大程度地减少能量消耗是非常必要的。     

Localized Ligand Induced Electroless Plating (LIEP) Process for the Fabrication of Copper Patterns Onto Flexible Polymer Substrates

The “ligand induced electroless plating (LIEP) process” is a simple process to obtain localized metal plating onto flexible polymers such as poly(ethylene terephtalate) and polyvinylidene fluoride sheets. This generic and cost‐effective process, efficient on any common polymer surface, is based on the covalent grafting by the GraftFast process of a thin chelating polymer film, such as poly(acrylic acid), which can complex copper ions. The entrapped copper ions are then chemically reduced in situ and the resulting Cu⁰ species act as a seed layer for the electroless copper growth which, thus, starts inside the host polymer. The present work focuses on the application of the LIEP process to the patterning of localized metallic tracks via two simple lithographic methods. The first is based on a standard photolithography process using a positive photoresist masking to prevent the covalent grafting of PAA in designated areas of the polymer substrate. In the second, the patterning is performed by direct printing of the mask with a commercial laser printer. In both cases, the mask was lifted off before the copper electroless plating step, which provides ecological benefits, since only the amount of copper necessary for the metallic patterning is used.