Recycled polypropylene with improved thermal stability and melt processability

Journal of Thermal Analysis and Calorimetry - Polypropylene (PP) is a versatile polymer, with a wide range of applications, from household appliances to packaging and automotive components....     

Investigation of the feeding effect on the 13C/12C isotope ratio of the hormones in bovine urine using gas chromatography/combustion isotope ratio mass spectrometry

The effect of the feeding on the 13C/12C isotope ratio of four endogenous steroid hormones testosterone (T), epi-testosterone (epi-T), dehydroepiandrosterone (DHEA) and etiocholanolone (ETIO) in bovine urine was investigated. An analytical method to determine the accurate isotope ratio was developed including an extensive clean up followed by enrichment of the analytes in two steps of HPLC fractionation. Feeding experiments with four young animals were performed using C3 and C4 plants (grass, maize silage, hay, etc.) over a time period of about 280 days. One cattle was used as a control animal with no change of its diet over the full period. The detection of the 13C/12C isotope ratio of the acetylated extracts was performed by gas chromatography/combustion isotope ratio mass spectrometry. After the first change of the feeding from C4 to C3 plants significant changes of the delta 13C % values were observed from the -19 to -23% level to the -24 to -32% level for etiocholanolone and epi-testosterone in urine of three animals, whereas the DHEA values remained under the level of the two metabolites. Testosterone could not be detected with GC-C-IRMS due to its low concentration in young animals. After the second change of the diet from C3 to C4 plants (after 222 days), the measured delta 13C % values have been stabilised at the original level. The results show that in case of the feeding with only C3 plants the endogenous delta values of -32% can be reached. In this case the contribution of exogenous material with a delta value of -32% could not be detected independently of the concentration. If the diet contains C4 plants the difference or the ratio of the delta 13C % values becomes the determinant in the discriminatory power. For validation of the method a human and a cattle were treated with testosterone and the delta 13C % values were measured in incurred human and cattle urine.     

锰基催化剂在催化柴油炭烟燃烧中的应用

柴油机排放的炭烟颗粒引起了严重的环境污染并对人体健康造成了极大的危害,引起人们的广泛关注。目前,催化净化技术是控制柴油机尾气炭烟颗粒排放最有效和研究最广泛的技术手段之一,其中高性能催化剂的研发是催化净化技术应用最为关键的因素。本文总结了近年来锰基催化剂材料在催化柴油机炭烟燃烧中的研究进展,重点介绍了单组分锰基催化剂、复合结构锰基氧化物催化剂、固定结构锰基氧化物催化剂(钙钛矿型、尖晶石型、水滑石型)等的研究进展,并简述了锰基催化剂材料在同时消除炭烟颗粒和氮氧化物方面的研究进展。最后,提出了锰基催化剂在催化柴油机炭烟燃烧中存在的问题并对其发展前景进行了展望。     

Thermomechanical,calorimetric and magnetic properties of a Ni–Ti shape-memory alloy wire

Journal of Thermal Analysis and Calorimetry - In this work, some physical properties of a commercial Ni–Ti (nitinol) shape-memory alloy with cylindrical geometry (wire) were investigated; the...     

Metal-Assisted Opening of Intact P4 Tetrahedra

The reactivity of ruthenium and manganese complexes bearing intact white phosphorus in the coordination sphere was investigated towards the low-valent transition-metal species [Cp′′′Co] (Cp′′′=η⁵-C₅H₂-1,2,4-tBu₃) and [L⁰M] (L⁰=CH[CHN(2,6-Me₂C₆H₃)]₂; M=Fe, Co). Remarkably, and irrespective of the metal species, the reaction proceeds by the selective cleavage of two P–P edges and the formation of a square-planar cyclo-P₄ ligand. The reaction products [{CpRu(PPh₃)₂}{CoCp′′′}(μ,η^1:4-P₄)][CF₃SO₃] ( 5 ), [{Cp^BIGMn(CO)₂}₂{CoCp′′′}(μ,η^1:1:4-P₄)] ( 6 ) and [{Cp^BIGMn(CO)₂}₂{ML⁰}(μ,η^1:1:4-P₄)] (Cp^BIG=C₅(C₆H₄nBu)₅; L⁰=CH[CHN(2,6-Me₂C₆H₃)]₂; M=Fe ( 7 a ), Co ( 7 b )), respectively, were fully characterized by single-crystal X-ray diffraction and spectroscopic methods. The electronic structure of the cyclo-P₄ ligand in the complexes 5 – 7 is best described as a π-delocalized P₄²⁻ system, which is further stabilized by two and three metal moieties, respectively. DFT calculations envisaged a potential intermediate in the reaction to form 5 , in which a quasi-butterfly-shaped P₄ moiety bridges the two metals and behaves as an η³-coordinated ligand towards the cobalt center.     

Thermal and mechanical behavior of biodegradable polyester films containing cellulose nanofibers

Journal of Thermal Analysis and Calorimetry - Agricultural waste is a valuable source of advanced materials. Cheap nanocellulose may be obtained from plum shells agricultural residues and further...     

Water-soluble J-type rosette nanotubes with giant molar ellipticity

A new self-assembling tricyclic module (×K1) featuring the Watson-Crick H-bonding arrays of guanine and cytosine fused to an internal pyridine ring was synthesized. When dissolved in water at room temperature, this module rapidly self-assembles into hexameric rosettes, which then stack to form J-type rosette nanotubes (RNTs) with increased inner/outer diameters and the largest molar ellipticity ever reported (4 × 10(6) deg·M(-1)·m(-1)). Using a combination of imaging and spectroscopic techniques we established the structure of ×K1-RNT and have shown that the extended π system of the self-assembling module resulted in a new family of J-type RNTs with enhanced intermodular electronic communication.     

Highly active heterogeneous palladium nanoparticle catalysts for homogeneous electrophilic reactions in solution and the utilization of a continuous flow reactor

A highly active heterogeneous Pd-nanoparticle catalyst for the intramolecular addition of phenols to alkynes was developed and employed in a continuous flow reaction system. Running the reaction in flow mode revealed reaction kinetics, such as the activation energy and catalyst deactivation, and provides many potential practical advantages.