1,3,4-Oxadiazole-containing hybrids as potential anticancer agents: Recent developments,mechanism of action and structure-activity relationships

Chemotherapy is an important therapeutic approach for the treatment of cancer. Currently, many anticancer drugs are available in the market that plays an important role in cancer treatment, but concerns such as, drug resistance and side effects create an urgent need for the development of new anti-tumor drugs with high potency and less side effects. Heterocycles are of great interest due to their fascinating anticancer activity. Among them, 1,3,4-oxadiazoles showed attracting anti-tumor activity and its derivatives are under clinical trials for the treatment of cancer. Hybridization of 1,3,4-oxadiazole moiety with other heterocyclic pharmacophoresis a promising approach to overcome various disadvantages of current anticancer drugs such as drug resistance, toxicity, and other side effects. Thus, 1,3,4-oxadiazole-heterocycle hybrids occupy a significant position in the discovery of anti-tumor drugs. Among the reported oxadiazole-based hybrids reviewed here, compounds 45i, 59j, and 62x showed the highest anticancer activity with IC₅₀ values in the nanomolar range. This review summarizes the recent developments in the anticancer potential, structure–activity relationships, and mechanisms of actions of 1,3,4-oxadiazole-heterocycle hybrids.     

Charged dislocations in ionic crystals

Experiments and theories concerning charged dislocations in alkali halide crystals are reviewed in detail, with particular attention to the way in which the experiments should be interpreted and to the range of applicability of the sweep-up and various forms of thermal-equilibrium models. Possible effects on mechanical properties and internal friction are analysed. The transient and steady-state effects of plastic deformation on ionic conductivity are described and new interpretations involving charged dislocations are proposed. A survey of results on the scattering of light by alkali halide single crystals leads to the conclusion that charged dislocations do not play an important role.

Evidence about charges on surfaces and on dislocations in AgCl and AgBr is reviewed and compared with that for alkali halides. Comparisons are also made with MgO, the CsCl and CaF₂ structures, semiconductors and ice.     

Near-Infrared spectroscopy and hyperspectral imaging for non-destructive quality assessment of cereal grains

Hyperspectral imaging (HSI) combines spectroscopy and imaging, providing information about the chemical properties of a material and their spatial distribution. It represents an advance of traditional Near-Infrared (NIR) spectroscopy. The present work reviews the most recent applications of NIR spectroscopy for cereal grain evaluation, then focuses on the use of HSI in this field. The progress of research from ground material to whole grains and single kernels is detailed. The potential of NIR-based methods to predict protein content, sprout damage and α-amylase activity in wheat and barley is shown, in addition to assessment of quality parameters in other cereals such as rice, maize and oats, and the estimation of fungal infection. This analytical technique also offers the possibility to rapidly classify grains based on properties such as variety, geographical origin, kernel hardness, etc. Further applications of HSI are expected in the near future, for its potential for rapid single-kernel analysis.     

Liapunov functions and error bounds for approximate solutions of ordinary differential equations

Summary It is shown that Liapunov functions may be used to obtain error bounds for approximate solutions of systems of ordinary differential equations. These error bounds may reflect the behaviour of the error more accurately than other bounds.     

Nuclear analysis applications in cooperative texas forensic investigation program

For the past two years, a cooperative nuclear forensic investigation program has been in operation in the Nuclear Reactor Laboratory at the University of Texas at Austin. An essential partner in this program has been the Crime Laboratories of the Texas Department of Public Safety, Under this program, both routine analyses of typical physical evidence samples and comprehensive survey analyses of classes of materials with forensic importance have been carried out. Both radioisotope-excited nondispersive X-ray fluorescence and multielement instrumental neutron activation analyses have been used, the first technique for screening incoming samples and performing macro-constituent analyses and the second for performing quantitative trace element analyses. Close coordination of routine analyses with the Crime Laboratories has provided supportive and complementary analyses of physical trace evidence samples for the preparation of investigative results. Carefully selected survey projects, such as the trace element characterization of safe platers and shotgun pellets described in this paper, have contributed to the development of background data available for forensic analysis in other laboratories.     

Concerted and stepwise proton-coupled electron transfers in aquo/hydroxo complex couples in water: oxidative electrochemistry of [Os(II)(bpy)(2)(py)(OH(2))](2+)

Successive oxidation of transition metal(II) aqua complexes (M(II)OH(2) to M(III)OH) is a domain in which proton-coupled electron transfer reactions are extremely common. The mechanism of these PCET reactions-concerted or stepwise-is an important issue in the understanding and design of natural or artificial systems catalyzing the formation of dioxygen by four-electron oxidation of water. Concerted proton-coupled electron transfer from an aqua metal(II) to a hydroxo metal(III) complex requires the close proximity of a proton-accepting group with a pK value between those of the aqua complexes. Otherwise, stepwise electron-proton or proton-electron pathways involving high-energy intermediates are followed. Concerted proton-electron pathways involving water as proton-acceptor or proton-donor group are inefficient. Cyclic voltammetry of the title complex in buffered aqueous solution and re-examination of previous results for the same complex attached to an electrode surface are used to establish these conclusions, which provide a starting point on the route to higher degrees of oxidation, such as those involved in the catalysis of water oxidation.     

Scanning electrochemical microscopy (SECM) studies of catalytic EC' processes: theory and experiment for feedback, generation/collection and imaging measurements

This paper describes the use of scanning electrochemical microscopy (SECM) in the tip generation/substrate collection (TG/SC), or feedback, mode and substrate generation/tip collection (SG/TC) mode to measure homogeneous kinetics in the catalytic EC' process. Theoretical analyses of both configurations have been developed numerically to allow the optimal conditions for sensitive kinetic measurements to be determined. This is shown to involve collection efficiency measurements as a function of tip-substrate electrode distance in the case of TG/SC measurements and tip (collector current) images in a plane normal to the substrate electrode for the SG/TC mode. An important consideration for the SECM configuration (particularly for TG/SC and feedback measurements) is that the electroinactive co-reactant may be depleted more significantly than with other electrode geometries, because of cycling of the redox couple in the tip/substrate electrode gap, while the co-reactant can only enter this gap by hindered diffusion. The approaches described are examined through studies of the oxidation of amidopyrine by electrogenerated Fe(CN) in 0.5 mol dm(-3) aqueous KOH solution. A second-order rate constant of 390 ± 80 dm(3) mol(-1) s(-1) is obtained from TG/SC measurements, consistent with SG/TC quantitative imaging measurements. The consistency of the kinetic measurements confirms the validity of the approaches described. The kinetic constant is lower than expected based on previous ultramicroelectrode (UME) studies, and this is attributed to the fact that background currents for the direct heterogeneous oxidation of amidopyrine are more significant with conventional UME measurements, which will tend to enhance the current measured and may therefore lead to an overestimation of kinetic constants. The TG/SC approach, on the other hand, provides a means of making dual-electrode collection efficiency measurements with diffusional feedback of the redox couple, leading to superior voltammetric responses and enabling more accurate kinetic determination.