Ni+ reactions with aminoacrylonitrile, a species of potential astrochemical relevance

The reaction of aminoacrylonitrile, a species of astrochemical interest, with Ni(+)((2)D(5/2)) was investigated by means of mass spectrometry techniques and density functional theory calculations. The dominant fragmentations in the MIKE spectrum correspond to the loss of [C2,N,H3], HCN, and NH3, the loss of H2 being very minor. The structure and bonding of the different aminoacrylonitrile-Ni(+) complexes were investigated at the B3LYP/6-311G(d,p) level of theory. The same approach was employed in our survey of the corresponding potential energy surface. This survey indicates that the [C2,N,H3] neutral product can be formed either as ketenimine (CH2CNH) or acetonitrile. The formation of the latter is significantly more exothermic but involves slightly higher activation barriers; so very likely, both isomers are produced along the reaction process. The lost of HNC is not competitive with the loss of HCN, because when the former is formed the products lie higher in energy and the corresponding mechanisms involve energy barriers above the entrance channel. The loss of NH3 is associated with the formation of a complex between cyanoacetylene, HCCCN, which is very abundant in the interstellar media, and Ni(+).     

Spectrophotometric determination of pipazethate HCl, dextromethorphan HBr and drotaverine HCl in their pharmaceutical preparations

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of pipazethate hydrochloride, dextromethorphan hydrobromide and drotaverine hydrochloride using chromotrope 2B (C2B) and chromotrope 2R (C2R). The method consists of extracting the formed ion-associates into chloroform in the case of pipazethate HCl and dextromethorphan HBr or into methylene chloride in the case of drotaverine HCl. The ion-associates exhibit absorption maxima at 528, 540 and 532 nm with C2B and at 526, 517 and 522 nm with C2R for pipazethate HCl, dextromethorphan HBr and drotaverine HCl, respectively. The calibration curves resulting from the measurements of absorbance-concentration relations (at the optimum reaction conditions) of the extracted ion-pairs are linear over the concentration range 4.36-52.32 microg mL(-1) for pipazethate, 3.7-48.15 microg mL(-1) for dextromethorphan and 4.34-60.76 microg mL(-1) for drotaverine, respectively. The effect of acidity, reagent concentration, time, solvent and stoichiometric ratio of the ion-associates were estimated. The molar absorptivity and Sandell sensitivity of the reaction products were calculated. Statistical treatment of the results reflects that the procedure is precise, accurate and easily applied for the determination of the drugs under investigation in pure form and in their pharmaceutical preparations.     

The synthesis and study of fluorescent PAMAM-based dendritic molecules

New water soluble and fluorescent PAMAM-based dendritic molecules based on the naphthalimide derivative 7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one as the fluorescent unit, have been prepared and their photophysical properties studied in aqueous solution over a wide pH range. The dendrons are all strongly fluorescent through an intramolecular charge transfer (ICT) excited state, but this can be modulated by photoinduced electron transfer (PeT) processes, which increases with higher PAMAM dendron generation.     

Determination of an unknown source term and the temperature distribution for the linear heat equation involving fractional derivative in time

We consider the inverse problem of finding the temperature distribution and the heat source whenever the temperatures at the initial time and the final time are given. The problem considered is one dimensional and the unknown heat source is supposed to be space dependent only. The existence and uniqueness results are proved.     

Thiosemicarbazides in heterocyclization

This review summarizes the preparation of substituted thiosemicarbazides with their application with synthesis of important linear and heterocyclic compounds. J. Heterocyclic Chem., (2011).     

Long‐term consequences of single and multiple mild blast exposure on select physiological parameters and blood‐based biomarkers

Mild traumatic brain injury (mTBI), especially when it is repeated (rmTBI), can lead to progressive degenerative diseases and lasting neuropsychiatric abnormalities. To better understand the long‐term pathobiological changes in mTBI and rmTBI, we exposed rats to single or repeated (5 total; administered on consecutive days) mild blast overpressure, monitored changes in physiological parameters, and determined the plasma levels of select biomarkers at 42 days post injury by proteomics. We unexpectedly found comparable changes in arterial oxygen saturation levels and heart rates of single‐injured (SI) and multiple‐injured (MI) rats throughout the observation period. Our analyses indicated lasting oxidative stress, vascular abnormalities, and neuronal and glial cell loss in both injured groups. However, MI rats exhibited a relatively more pronounced increase in the plasma levels of most of the tested markers—particularly those associated with inflammation—albeit the differences between the two injured groups were not statistically significant. Our findings indicate that the frequency of blast exposures is an important determinant of the resulting cumulative damage in rmTBI.     

Modeling and nonlinear control of a flexible-link manipulator

The problem of modeling and controlling the tip position of a one-link flexible manipulator is considered. The proposed model has been used to investigate the effect of the open-loop control torque profile, and the payload. The control strategy is based on the nonlinear State Dependent Riccati Equation (SDRE) design method in the context of application to robotics and manufacturing systems. In this paper, an experimental test-bed was developed to demonstrate the concept of end-point position feedback on a single-link elastic manipulator, and the control strategy for a single-link flexible manipulator. The controller is designed based on the nonlinear SDRE developed by the authors and applied to a flexible manipulator. The experimental results are compared with conventional PD controller strategy. The results reveal that the nonlinear SDRE controller is near optimal and robustly; and its performance is improved comparing to the PD control scheme.     

Thermophysical properties of gamma-irradiated LaFeO3 and YFeO3 orthoferrites

In the present work, LaFeO₃ and YFeO₃ orthoferrites were carefully prepared using the solid state high temperature ceramic and sintering technique. On these two materials, numerous measurements were applied before and after γ-absorbed dose (1.24 Mrad) namely, X-ray diffraction (XRD), DC-electrical conductivity, UV/Vis, IR, Mössbauer effect and EPR. Results obtained were explained, interpreted, and discussed in detail on the basis of lattice structure of the new perovskite investigated and the interaction of γ-radiation with the investigated materials. Finally the γ-induced functions are evaluated for electrical conduction, Mössbauer effect and EPR for the first time.     

Different Validated Methods for Determination of Cefditoren Pivoxil

JPC – Journal of Planar Chromatography – Modern TLC - Six, sensitive, precise and accurate methods have been developed for the determination of cefditoren pivoxil (CP). The first two...