Coal Handleability — A good or a bad coal?

The avalanching behaviour of two coal types was determined, one of good and the other of poor handleability characteristics. This revealed significant differences in the nature of flow of the coals. Analysis of the strange attractors of the weight series of avalanches enabled quanitification of this difference, and the establishment of practical, relative criteria for the measurement of coal handleability. These criteria will now enable a structured study of the variables that affect handleability, for example proportion of fines and moisture content, and industrial consumers of coal to specify minimum acceptable limits for its transport characteristics.     

Synthesis of tubular gold and silver nanoshells using silica nanowire core templates

We report the synthesis of tubular gold and silver nanoshells on silica nanowire core templates in solution. Silica nanowires were synthesized and characterized with optical and NMR methods. Gold nanoparticle seeds (2 to 3 nm) with weak repulsive surfactants such as tetrakis-hydroxymethyl-phosphonium chloride (THPC) were conjugated to the surface of these nanowires. A regrowth process was initiated from these nanoparticles on the surface of the silica nanowires dispersed in gold or silver stock solutions in the presence of reducing agents. Micrometers-long gold and silver tubular nanoshells (80-150 nm o.d.) were made, fully covering the silica nanowires.     

Induction and repair of cyclobuta-dithymidine photoproducts in hamster skin by solar-simulated UV radiation

The induction and repair of cyclobuta-dithymidine (T less than greater than T) photoproducts in hamster skin was measured following exposure to artificial solar radiation. DNA extracted from irradiated hamster epidermis was analyzed by enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody specific for T less than greater than T photoproducts. Between 49% and 58% of T less than greater than T antibody binding sites were eliminated from DNA by 24 h after radiation exposures comparable with approximately 60 - 120 min of midday sunlight, whereas all detectable T less than greater than T binding sites were eliminated by 24 h after a radiation exposure comparable with 30 min of sunlight.     

Core–shell and gradient morphology polymer particles analyzed by X‐ray photoelectron spectroscopy: Effect of monomer feed order

The synthesis of composite latex particles possessing core–shell and gradient morphologies, respectively, using seeded starve‐fed semibatch emulsion polymerization of styrene (St) and methyl methacrylate (MMA) is presented. The focus is on the effect of the monomer feed order on the particle morphology development. The particle morphology is assessed using a novel approach which entails comparing the experimental surface composition as a function of polymerization time (particle growth) obtained by X‐ray photoelectron spectroscopy with the predicted surface composition using a mass balance mathematical model. Both types of composite latexes (core–shell and gradient) feature changes with polymerization time in the oxygen/carbon surface composition which enables one to track the morphology development. Differential scanning calorimetry is also implemented to analyze the extent of phase separation. The monomer feed order is shown to play a crucial role—under the present conditions, gradient and core–shell particles are obtained if the feed order is St/MMA (St fed first), but not if the feed order is reversed. These findings illustrate that thermodynamic factors are important, given that thermodynamically it is more favorable for MMA‐rich chains to occupy the oil–water interface to reduce the interfacial tension. Systems where St is the second stage monomer lead to mixed structures rather than the targeted core–shell or gradient morphology with St‐rich chains at the particle surface. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2513–2526     

Efficiency of the dry–wet method for the MALDI‐MSI analysis of latent fingermarks

Matrix‐assisted laser desorption/ionisation mass spectrometry imaging (MALDI‐MSI) has proven to be a powerful analytical tool to investigate problems in several fields of life science. A novel application is in the field of forensics, particularly in the analysis of latent fingermarks. This technology enables images of the fingermark ridge detail and additional intelligence to be simultaneously obtained. Although several methods are available to deposit the MALDI matrix, to make the technology forensically operational, another deposition approach was devised and reported, namely the ‘dry–wet’ method. In the present study, the efficiency of the dry–wet method was evaluated and compared with the conventional spray coat methodology. Results indicate that the dry–wet method is superior for all the donors' typologies in terms of ion signal intensity and clarity of the ridge details. To underpin the reasons of this efficiency, scanning electron microscopy analyses were carried out in parallel to MALDI‐MSI experiments using matrices of different particle size. Results have confirmed that the particle size plays an important role in the efficiency of the method as higher quality images and higher intensity spectra are produced as the matrix particle size decreases. Copyright © 2013 John Wiley & Sons, Ltd.     

Initial investigation into the Suzuki-Miyaura vinylation of hindered aryl bromides utilizing potassium vinyltrifluoroborate

An initial study of the Suzuki-Miyaura cross-coupling of potassium vinyltrifluoroborate (2) and hindered aryl bromides is presented. Coupling of benzyl 3,5-bis(benzyloxy)-4-bromobenzoate (1) leads to a mixture of the desired styrene derivative, and the reduced product.     

Studies of microwave-enhanced Suzuki-Miyaura vinylation of electron-rich sterically hindered substrates utilizing potassium vinyltrifluoroborate

The Suzuki-Miyaura cross-coupling of sterically hindered and electron-rich ortho,ortho′-substituted aryl halides with potassium vinyltrifluoroborate utilizing microwave irradiation has been conducted while adjusting solvent ratio, irradiation time, and catalyst loading to find optimal conditions. Coupling of benzyl 3,5-bis(benzyloxy)-4-bromobenzoate leads to a mixture of the desired styrene derivative and the reduced product. 4-Bromo-1,3,5-trimethoxybenzene, methyl 4-bromo-3,5-dimethoxybenzoate, and mesitylene bromide were also coupled to test the breadth and scope of this methodology. Of these substrates tested only 4-bromo-1,3,5-trimethoxybenzene was not vinylated successfully, which is believed to be due to the electron-rich nature of this system.     

Alkanethiol-induced structural rearrangements in silica-gold core-shell-type nanoparticle clusters: an opportunity for chemical sensor engineering

Electrostatically bonded SiO2.Au nanoparticle clusters form by reaction of 3-aminopropylsilane-modified SiO2 spheres (470 nm) with citrate-coated gold nanoparticles (9.7 nm) in water. Reaction of the clusters with 0.01 M KBr or HCl solution induces desorption of the gold nanoparticles within minutes. Reaction of the clusters with alkanethiols CnH2n+1SH (n = 2-18) at 80 degrees C causes the gold nanoparticles to form stringlike gold nanoparticle structures for thiols with short alkane groups (n = 2, 3, 4) and hexagonally packed arrays of gold nanoparticles for thiols with long alkane groups (n = 5-18) on the silica surfaces. The structural changes indicate that the bonding between Au and SiO2 nanoparticles has changed from electrostatic to van der Waals. Elemental analyses show that the reaction with hexanethiol does not affect the Au/Si/O composition of the SiO2.Au cluster, and Raman spectra on the hexanethiol-reacted cluster indicate the formation of a thiol SAM on the gold nanoparticles. The thiol-reacted SiO2.Au clusters display characteristic shifts of the absorption maxima in the visible spectra, and there is an inverse relation between these shifts and the lengths of the alkyl groups in the thiols. This relationship can be understood in terms of the free electron model for metals. The use of SiO2.Au nanoparticle clusters as coulometric sensors for the qualitative detection of thiols is discussed.     

Pressurized liquid extraction using water/isopropanol coupled with solid-phase extraction cleanup for industrial and anthropogenic waste-indicator compounds in sediment

A broad range of organic compounds is recognized as environmentally relevant for their potential adverse effects on human and ecosystem health. This method was developed to better determine the distribution of 61 compounds that are typically associated with industrial and household waste as well as some that are toxic and known (or suspected) for endocrine-disrupting potential extracted from environmental sediment samples. Pressurized liquid extraction (PLE) coupled with solid-phase extraction (SPE) was used to reduce sample preparation time, reduce solvent consumption to one-fifth of that required using dichloromethane-based Soxhlet extraction, and to minimize background interferences for full scan GC/MS analysis. Recoveries from spiked Ottawa sand, commercially available topsoil, and environmental stream sediment, fortified at 4-720 μg per compound, averaged 76 ± 13%. Initial method detection limits for single-component compounds ranged from 12.5 to 520 μg/kg, based on 25 g samples. Results from 103 environmental sediment samples show that 36 out of 61 compounds (59%) were detected in at least one sample with concentrations ranging from 20 to 100,000 μg/kg. The most frequently detected compound, beta-sitosterol, a plant sterol, was detected in 87 of the 103 (84.5%) environmental samples with a concentration range 360-100,000 μg/kg. Results for a standard reference material using dichloromethane Soxhlet-based extraction are also compared.