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The behavior of nano-particles finds
a wide application in opto-electronic and semi-conductor devices. ZnS nano-crystals
were grown into poly-vinyl alcohol matrix by chemical route at different weight
percentage. Optical properties of both un-doped and doped with ZnS nano-crystalline
compounds were studied. The nano structure was characterized with the help of X-ray
diffraction (XRD) and Hi-resolution Transmission Electron Microscopy (HRTEM). Surface
morphology was studied with the help of Scanning Electron Microscopy (SEM). The
average particle sizes of ZnS, ZnS-Ni and ZnS-Mn were found to be 6.51, 7.3 and 12 nm respectively in TEM and
that obtained from Debye-Scherrer formula is about 2.3 and 2.5 nm for undoped and doped ZnS respectively.
Peak of Photo-luminescence (PL) emission spectra was obtained at 375 nm at room
temperature and another peak at 433 nm for Ni. Again the peak of Photo-luminescence
(PL) emission spectra was obtained at 334 nm at room temperature for Mn, Mn dependant
emission was found at 580 nm. These data showed successful doping. PL studies also
confirmed presence of dopant in the nano crystallites. Optical absorption studies
were carried out with UV-VIS Spectrophotometer and showed a strong absorbance at
wavelength 400 nm with a tendency towards blue shift. Selected area electron diffraction
(SAED) shows a set of four well defined rings corresponding to diffraction from
different planes of the nano crystallites. HRTEM image showed a well crystalline
ZnS doped with Ni and Mn. Both Raman spectra and XRD studies confirmed the well
crystalline states of ZnS.
Most of the earthquake faults in North-East India, China, mid Atlantic-ridge, the Pacific seismic belt and Japan are found to be predominantly dip-slip in nature. In the present paper a dip-slip fault is taken situated in an elastic layer over a viscoelastic half space representing the lithosphere-asthenosphere system. A movement of the dip-slip nature across the fault occurs when the accumulated stress due to various tectonic reasons e.g. mantle convection etc., exceeds the local friction and cohesive forces across the fault. The movement is assumed to be slipping in nature, expressions for displacements, stresses and strains are obtained by solving associated boundary value problem with the help of integral transformation and Green’s function method and a suitable numerical methods is used for computation. A detailed study of these expressions may give some ideas about the nature of stress accumulation in the system, which in turn will be helpful in formulating an earthquake prediction programme.
Piperacillin/tazobactam and ciprofloxacin are often used in combination as initial empiric anti-biotic therapy in critical ill patients. Especially in patients undergoing continuous renal replacement therapy (CRRT) the pharmacokinetics of antimicrobial agents can be highly variable. In order to avoid under- or overdosage of antibiotics therapeutic drug monitoring (TDM) is highly re-commendable. Based on two known HPLC assays for piperacillin a new method in combination with solid phase extraction (SPE) for the simultaneous determination of piperacillin and ciprofloxacin was developed. Method validation was performed according to the EMA guideline on validation of bioanalytical methods. The HPLC column used was a Perfect Bond ODS-HD C18 analytical column (100 mm × 4.6 mm i.d., particle size 5 μm), equipped with a guard column (10 mm × 4.6 mm, particle size 5 μm) containing the same packing material. Detection wavelength was set at 228 nm for piperacillin and benzylpenicillin was used as internal standard (IS). Ciprofloxacin was determined at two wavelengths (280 nm, 315 nm). This newly developed HPLC method in combination with SPE-extraction allows an accurate, precise, specific and efficient determination of piperacillin and ciprofloxacin in biological matrices. Results allow the calculation of all relevant pharmacokinetic data for critically ill patients undergoing CRRT and the optimization of dosing and TDM.