Development of a multiplex system to assess DNA persistence in taphonomic studies

In this study, we have developed a PCR multiplex that can be used to assess DNA degradation and at the same time monitor for inhibition: primers have been designed to amplify human, pig, and rabbit DNA, allowing pig and rabbit to be used as experimental models for taphonomic research, but also enabling studies on human DNA persistence in forensic evidence. Internal amplified controls have been added to monitor for inhibition, allowing the effects of degradation and inhibition to be differentiated. Sequence data for single‐copy nuclear recombination activation gene (RAG‐1) from human, pig, and rabbit were aligned to identify conserved regions and primers were designed that targeted amplicons of 70, 194, 305, and 384 bp. Robust amplification in all three species was possible using as little as 0.3 ng of template DNA. These have been combined with primers that will amplify a bacterial DNA template within the PCR. The multiplex has been evaluated in a series of experiments to gain more knowledge of DNA persistence in soft tissues, which can be important when assessing what material to collect following events such as mass disasters or conflict, when muscle or bone material can be used to aid with the identification of human remains. The experiments used pigs as a model species. When whole pig bodies were exposed to the environment in Northwest England, DNA in muscle tissue persisted for over 24 days in the summer and over 77 days in the winter, with full profiles generated from these samples. In addition to time, accumulated degree days (ADD) were also used as a measure that combines both time and temperature—24 days was in summer equivalent to 295 ADD whereas 77 days in winter was equivalent to 494 ADD.     

Thermal degradation pathways of nickel(II) bipyridine complexes to size-controlled nickel nanoparticles

Tris(bipyridine)nickel(II) chloride (1) and bis(bipyridine)nickel(II) chloride (2) pyrolize at heating rate of 50 °C/min to a maximum of 450 °C for 24 h under an inert atmosphere of flowing argon gas, to yield size-controlled nickel nanoparticles. Thermogravimetric studies of the complexes (1) and (2) and GC–MS analysis of the trapped volatile matter evolved during thermal degradation of the complexes indicate their clean decomposition pathway to zero-valent nickel. Both heating rate and argon gas flow rate affect purity, particle size, and shape of the particles. X-ray powder diffractometry and atomic force microscopy showed the formation of face-centered cubic (fcc) structured nickel particles having particle size in the range of 3.5–5.0 nm. Magnetic susceptibility measurements suggest nickel nanoparticles to be ferromagnetic in nature characterized by particle size–dependent Curie temperature and high coercivity that is comparable to the bulk iron.     

Characterization and differentiation of iron ores using X-ray diffractometry,k0 instrumental neutron activation analysis and inductively coupled plasma optical emission spectrometry

This study was aimed at developing methodology for the characterization and differentiation of iron ores from different ore deposits. X-ray diffractometry (XRD) was used for the determination of major and minor chemical phases in the ores, k₀-instrumental neutron activation analysis (k₀-INAA) and inductively coupled plasma optical emission spectrometry (ICP-OES) were employed for the determination of elemental profiles of iron ores. The quality of the ores was evaluated to establish their suitability to serve as a raw material for iron production. Principal component analysis was performed on the elemental data for the classification of ores. It was also shown that ores can be differentiated on the basis of rare earth elemental profiles. In this paper a new indicator, based on four elements (Ca, S, Sb, Yb), was proposed for the classification.

     

Micellization of Cationic Surfactant Cetyltrimethylammonium Bromide in Mixed Water-Alcohol Media

The effect of methanol, ethanol, and 1-propanol on cmc and degree of counter ion binding, β, of cetyltrimethylammonium bromide (CTAB) has been studied conductometrically. The micellization of CTAB in these water-alcohol media have been found to be both dependent on nature as well as the concentration of alcohol in water. The cmc values shift toward higher concentration with increase in alcoholic content up to certain concentration beyond which decrease in cmc is registered in case of all the alcohols. However, the maximum in the cmc versus concentration of alcohol shifts to lower concentration with the increase in number of carbons in alcohol. β shows the inverse peaked behaviour in conformity with the cmc variation. The effects viz. solvent modifying tendency of alcohols and their tendency of penetration into the micelles have been used to interpret their effect on micellization of CTAB.     

Application of flow field-flow fractionation for the characterization of macromolecules of biological interest: a review

An overview is given of the recent literature on (bio) analytical applications of flow field-flow fractionation (FlFFF). FlFFF is a liquid-phase separation technique that can separate macromolecules and particles according to size. The technique is increasingly used on a routine basis in a variety of application fields. In food analysis, FlFFF is applied to determine the molecular size distribution of starches and modified celluloses, or to study protein aggregation during food processing. In industrial analysis, it is applied for the characterization of polysaccharides that are used as thickeners and dispersing agents. In pharmaceutical and biomedical laboratories, FlFFF is used to monitor the refolding of recombinant proteins, to detect aggregates of antibodies, or to determine the size distribution of drug carrier particles. In environmental studies, FlFFF is used to characterize natural colloids in water streams, and especially to study trace metal distributions over colloidal particles. In this review, first a short discussion of the state of the art in instrumentation is given. Developments in the coupling of FlFFF to various detection modes are then highlighted. Finally, application studies are discussed and ordered according to the type of (bio) macromolecules or bioparticles that are fractionated.     

Electronic excitation dynamics in multichromophoric systems described via a polaron-representation master equation

We derive a many-site version of the non-Markovian time-convolutionless polaron master equation [Jang et al., J. Chem Phys. 129, 101104 (2008)] to describe electronic excitation dynamics in multichromophoric systems. By treating electronic and vibrational degrees of freedom in a combined frame (polaron frame), this theory is capable of interpolating between weak and strong exciton-phonon coupling and is able to account for initial non-equilibrium bath states and spatially correlated environments. Besides outlining a general expression for the expected value of any electronic system observable in the original frame, we also discuss implications of the Markovian and Secular approximations highlighting that they need not hold in the untransformed frame despite being strictly satisfied in the polaron frame. The key features of the theory are illustrated using as an example a four-site subsystem of the Fenna-Mathews-Olson light-harvesting complex. For a spectral density including a localised mode, we show that oscillations of site populations may only be observed when non-equilibrium bath effects are taken into account. Furthermore, we illustrate how this formalism allows us to identify the electronic and vibrational components of the oscillatory dynamics.