Crystal growth and ambient and high pressure study of the reentrant superconductor Tm_2Fe_3Si_5

We report single crystal growth of the reentrant superconductor Tm_2Fe_3Si_5, and measurements of the anisotropic static magnetic susceptibility \chi(T) and isothermal magnetization M(H), ac susceptibility \chi_ac(T), electrical resistivity \rho(T) and heat capacity C(T) at ambient pressure and \chi_ac(T) at high pressure. The magnetic susceptibility along the c-axis \chi_c(T) shows a small maximum around 250 K and does not follow the Curie-Weiss behavior while the magnetic susceptibility along the a-axis \chi_a(T) follows a Curie-Weiss behavior between 130 K and 300 K with a Weiss temperature \theta and an effective magnetic moment \mu_eff which depend on the temperature range of the fit. The easy axis of magnetization is perpendicular to the c-axis and \chi_a/\chi_c = 3.2 at 1.8 K. The ambient pressure \chi_ac(T) and C(T) measurements confirm bulk antiferromagnetic ordering at T_N = 1.1 K. The sharp drop in \chi_ac below T_N is suggestive of the existence of a spin-gap. We observe superconductivity only under applied pressures P\geq 2 kbar. The temperature-pressure phase diagram showing the non-monotonic dependence of the superconducting transition temperature T_c on pressure P is presented.Comment: 7 pages, 8 figure

Noise spectroscopy and interlayer phase-coherence in bilayer quantum Hall systems

Bilayer quantum Hall systems develop strong interlayer phase-coherence when the distance between layers is comparable to the typical distance between electrons within a layer. The phase-coherent state has until now been investigated primarily via transport measurements. We argue here that interlayer current and charge-imbalance noise studies in these systems will be able to address some of the key experimental questions. We show that the characteristic frequency of current-noise is that of the zero wavevector collective mode, which is sensitive to the degree of order in the system. Local electric potential noise measured in a plane above the bilayer system on the other hand is sensitive to finite-wavevector collective modes and hence to the soft-magnetoroton picture of the order-disorder phase transition.Comment: 5 pages, 2 figure

FORMULATION AND EVALUATION OF MICROEMULSION CONTAINING NEEM SEED OIL

Objective: The objective of the present study was to formulate Microemulsion containing seed oil. Neem seed (Azadirachtaindica) oil was extracted from its seeds by the soxhlet apparatus. Acetone is used as a solvent. PEG 400 and Carbopol 940p was select as surfactant, co-surfactant and hydrogel thickening agent. Microemulsions were characterized for pH, viscosity, spreadability, in vitro drug transport study and in vivo antibacterial activity and shows satisfactory results. Antibacterial activity of formulation against E. coli Shows at a concentration of 3%. The neem seed oil microemulsion has the potential for antibacterial activity. Methods: A ratio of surfactant and cosurfactant i.e, S/CoSchoosen and corresponding mixture was made. The mixture was mixed with oil. Each mixture was mixed thoroughly using magnetic stirrer until homogenous dispersion/solution was obtained. Double distilled water was used in this formulations as to prevent the incorporation of surface active impurities. The mixture was titrated with water and ambient temperature with constant stirring at the endpoint where the mixture become clouded, the quantity of aquous phase added. The percentage of three different pseudo-phases incorporated were calculated.  Results: Solubility studies in various solvents reveals that the oil is insoluble in distilled water and ethanol. Soluble in methanol. Conclusion: It was observed that the microemulsion having multilamellar nature. Batches with carbopol shows better homogenous distribution. The stability of microemulsion prepared with carbopol 71 was gretter than with xanthan gum. The in vitro study of microemulsion was performed and Batch (F7) is optimized batch which shows highest drug release

FORMULATION AND EVALUATION OF CRACK CREAM FROM PLANT EXTRACTS

Objective: The main aim of our research was to develop an anti-cracked heels cream formulation consisting of Hedychium Spicatum, Aloe barbadensis, Azadirachta indica for the treatment of cracked heels. Methods: An anti-cracked heels cream formulation consisting of Hedychium Spicatum, Aloe barbadensis, Azadirachta indica extracts was prepared. Microbiological studies were performed the safety of materials used in the formulation. Results: The developed cream consisting of Hedychium Spicatum, Aloe barbadensis, Azadirachta indica was found to be safe and effective for the treatment of cracked heels. Conclusion: It can be concluded that herbal creams without side effects having anti-inflammatory property can be used as the provision of a barrier to protect the skin

FORMULATION AND EVALUATION OF LIPOSOMAL GEL CONTAINING EXTRACT OF PIPRINE

Objective: The objective of present research work is to develop Liposomes as a carrier system for 70% Hydroalcoholic extract, its incorporation in to gel formulations and to characterize the prepared and develop Liposomal gel formulation. There are many reports revealing the pharmacological potential of Piper Nigrum. Methods: Cholestrol in various weight ratios were dissolved in 10 ml of Methanol: Chloroform (1:1) ratio used as a solvent. The extract solution was taken in a 500 ml round bottom flask. The flask was rotated in rotary flash evaporator at 40 rpm for 20 min in the thermostatically controlled water bath at 40 °C under vacuum 240 mmHg. The solvent was slowly removed by this process, and a very thin film of dry lipids was formed on the flask. The dry lipid film was slowly hydrated with 10 ml of Saline Phosphate Buffer pH 7.4 containing Insulin Drug. The flask was once again rotated at the same speed as before and at room temperature for 2 hr. The liposomal was left to overnight at 4°C, full lipid hydration. Results: This study was done for herbal formulations used for topical delivery of therapeutic agents at the time of injury to accelerate skin repair in the shortest time possible, with minimal pain. Plant Piper Nigrum. Family Piperaceac is extensively used. Conclusion: The present study revealed liposomal gel as an efficient carrier for herbal extract. Keywords: Piperine, Gel, Herbal extract, Liposomes, Liposomal gel

Two dimensional bulge disk decomposition

We propose a two dimensional galaxy fitting algorithm to extract parameters of the bulge, disk, and a central point source from broad band images of galaxies. We use a set of realistic galaxy parameters to construct a large number of model galaxy images which we then use as input to our galaxy fitting program to test it. We find that our approach recovers all structural parameters to a fair degree of accuracy. We elucidate our procedures by extracting parameters for 3 real galaxies -- NGC 661, NGC 1381, and NGC 1427.Comment: 23 pages, LaTeX, AASTEX macros used, 7 Postscript figures, submitted to Ap

TASTE ABATEMENT AND CHARACTERIZATION OF DISPERSIBLE TABLETS OF ARTEMETHER PREPARED BY HOT MELT EXTRUSION

Objective: The aim of this study was to formulate and evaluate a taste-masked formulation using hot melt extrusion approach for artemether.Methods: Taste masking of artemether was done by preparing solid dispersion with coating polymer kollicoatsmartseal 30D using hot melt extrusion. The prepared solid dispersion was subjected to taste masking evaluation like sensory evaluation parameters against five levels set for taste evaluation using artemether as control standard along with in vitro release studies in simulated salivery fluid. After taste evaluation of solid dispersion was subjected to the formulation of dispersible tablets by direct compression method. The final taste masking evaluation of dispersible tablets of solid dispersion containing artemether were done by a sensory evaluation panel of nine members along with in vitro release study in simulated salivary and gastric fluid.Results: The percent drug content was found 35.09±0.06 % in solid dispersion. The drug excipients compatibility studies performed with the help of FTIR instrument and DSC that indicates there were no interactions between drug and polymers. Solid dispersions (1:1, 1:2, 1:3 drug polymer ratio) of artemether were evaluated by sensory evaluation panel from which 1:3 drug: polymer solid dispersion was found more palatable. Release rate study in simulated salivary fluid shown no release but shows release of drug in simulated gastric fluids which indicates that the drug was taste masked. The optimized batch of dispersible tablets (F1) were subjected for evaluation parameters like dispersion time (70±1.90), wetting time (63±1.86), etc. Dissolution studies of optimized formulation indicated that the polymer does not allow drug to release in simulated salivery pH 6.8 but shows immediate release in simulated gastric pH which also confirms taste masking efficiency of polymer. Final optimized F1 batch evaluated for taste masking evaluation by sensory evaluation panel using pure drug as control standard found to be palatable.Conclusion: It may be concluded that kollicoatsmartseal 30D could mask the taste of the drug in salivary pH and shows drug release at gastric pH which confirms its efficiency for taste masking

Rheological Investigation of The Network Structure in Mixed Gels of Kappa and Iota Carrageenan

Carrageenans comprise linear sulfated high molecular weight polysaccharides obtained from seaweeds and are routinely used in food and home/personal care industries. Various kinds of carrageenans differ from others based on the ester sulfate group location on the polysaccharide chains. Pure and mixed systems of Kappa Carrageenan and Iota Carrageenan undergo a three-dimensional gel network structure formation or dissociation with a change in temperature. During the sol-gel and gel-sol transitions, the Carrageenan systems pass through a unique critical gel state, where dynamic moduli are scale-invariant owing to the self-similar structure of the three-dimensional network. In this work, we obtain the critical gel state associated with pure and mixed systems of Kappa and Iota Carrageenan during cooling and heating by exploring the material behavior for a range of frequencies. Interestingly, on the one hand, the mixed gels show a higher critical sol-gel transition temperature compared to the pure systems at equal individual concentrations. On the other hand, the low temperature moduli of mixed gels are closer to that of Kappa Carrageenan when the concentration of the same is more than half in the mixture. The rheological measurements demonstrate that the Kappa Carrageenan strongly affects the nature of aggregation of double helices of Iota Carrageenan, but Iota Carrageenan does not have a significant influence on that of Kappa Carrageenan. These results suggest an associative, interactive network formation between Kappa and Iota Carrageenan in the mixture, such that the gel behavior is predominantly influenced by Kappa Carrageenan

Magnetic Ordering and Superconductivity in the RE2_2Ir3_3Ge5_5 (RE = Y, La-Tm, Lu) System

We find that the compounds for RE = Y, La-Dy, crystallize in the tetragonal Ibam (U$_2$Co$_3$Si$_5$ type) structure whereas the compounds for RE = Er-Lu, crystallize in a new orthorhombic structure with a space group Pmmn. Samples of Ho$_2$Ir$_3$Ge$_5$ were always found to be multiphase. The compounds for RE = Y to Dy which adopt the Ibam type structure show a metallic resistivity whereas the compounds with RE = Er, Tm and Lu show an anomalous behavior in the resistivity with a semiconducting increase in $\rho$ as we go down in temperature from 300K. Interestingly we had earlier found a positive temperature coefficient of resistivity for the Yb sample in the same temperature range. We will compare this behavior with similar observations in the compounds RE$_3$Ru$_4$Ge$_{13}$ and REBiPt. La$_2$Ir$_3$Ge$_5$ and Y$_2$Ir$_3$Ge$_5$ show bulk superconductivity below 1.8K and 2.5K respectively. Our results confirm that Ce$_2$Ir$_3$Ge$_5$ shows a Kondo lattice behavior and undergoes antiferromagnetic ordering below 8.5K. Most of the other compounds containing magnetic rare-earth elements undergo a single antiferromagnetic transition at low temperatures (T$\leq$12K) while Gd$_2$Ir$_3$Ge$_5$, Dy$_2$Ir$_3$Ge$_5$ and Nd$_2$Ir$_3$Ge$_5$ show multiple transitions. The T$_N$'s for most of the compounds roughly scale with the de Gennes factor. which suggests that the chief mechanism of interaction leading to the magnetic ordering of the magnetic moments may be the RKKY interaction.Comment: 25 pages, 16 figure