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131.
Lipid matrix based carriers are able to provide sustained release, increase the drug transport into cancer cells and overcome the drug resistance. Therefore, nanostructured lipid carriers (NLC) were prepared and coated with polysorbate 80 to overcome the blood brain barrier for achieving effective treatment of meningeal leukemia. NLC were prepared by melt emulsification followed by ultrasonication, producing particles of 90.7 +/- 4.28 nm size with appreciable amount of drug entrapment (49.5 +/- 2.24%), considering the hydrophilic nature of the drug. The polysorbate 80 coated cytarabine loaded NLC (Cyt-NLC) thus produced were non-aggregated and had almost spherical, smooth and uniform shape. Results of DSC and XRD studies indicated that Cyt was entrapped inside the lipid as molecular dispersion. In-vitro release pattern showed initial fast release (15.87 +/- 1.524% in 1 h) followed by sustained release upto 72 h (89.90 +/- 1.11%). In-vitro cell line studies demonstrated that blank NLC showed no significant cytotoxic effects on leukemic EL-4 cells whereas Cyt-NLC exhibited concentration dependent cytotoxicity. At 48 and 72 h, cytotoxicity of Cyt-NLC was found to be significantly more than that of Cyt solution and the percentage cell viability decreased with increasing concentration of Cyt-NLC. The lyophilized Cyt-NLC formulation was found to be stable with respect to size and total drug content at refrigerated condition (2-8 degrees C) for 3 months. These results suggest that polysorbate 80 coated Cyt-NLC can be explored for treatment of meningeal leukemia owing to their ability of sustained drug release and improved cytotoxic effect in leukemic EL-4 cell line. 相似文献
132.
Duradundi Sawant Badkar Krishna Shankar Pandey G. Buvanashekaran 《The International Journal of Advanced Manufacturing Technology》2013,65(9-12):1319-1338
Laser transformation hardening (LTH) is an innovative and advanced laser surface modification technique as compared to conventional transformation hardening processes and has been employed in aerospace, marine, chemical applications, heat exchangers, cryogenic vessels, components for chemical processing and desalination equipment, condenser tubing, airframe skin, and nonstructural components which introduces the advantageous residual stresses into the surface, improving the mechanical properties like wear, resistance to corrosion, tensile strength, and fatigue strength. In the present study, LTH of commercially pure titanium, nearer to ASTM grade 3 of chemical composition was investigated using continuous wave 2 kW, Nd: YAG laser. The effect of laser process variables such as laser power, scanning speed, and focused position was investigated using response surface methodology (RSM) and artificial neural network (ANN) keeping argon gas flow rate of 10 lpm as fixed input parameter. This paper describes the comparison of the heat input (HI) and ultimate tensile strength (σ) (simply called as tensile strength) predictive models based on ANN and RSM. The paper also presents the effect of laser process variables on the HI and ultimate σ. The research work also emphasizes on the effect of HI on σ. The experiments were conducted based on a three-factor, three-level Box–Behnken surface statistical design. Quadratic polynomial equations were developed for proper process parametric study for its optimal performance characteristics. The experimental results under optimum conditions were compared with the simulated values obtained from the RSM and ANN model. Adequacy of the developed models was tested by analysis of variance technique. A multilayer feed-forward neural network with a Levenberg–Marquardt back-propagation algorithm was adopted to develop the relationships between the laser hardening process parameters, HI, and ultimate σ. The performance of the developed ANN models were compared with the second-order RSM mathematical models of HI and σ. There was good agreement between the experimental and simulated values of RSM and ANN. The comparison clearly indicates that the ANN models provide more accurate prediction compared to the RSM models. It has been found that there is a trend of increased tensile strength with the decrease of hardening heat input and a trend of increased tensile strength with the increase of hardening cooling rate. As heat input decreases, there will be a faster cooling rate. Considering the effect of HI on ultimate σ, it was found that the lower the heat input, the faster cooling rate. The details of experimentation, model development, testing, validation of models, effect of laser process variables on heat input and ultimate σ, effect of HI on σ, and performance comparison of RSM and ANN models are presented in the paper. The results of Box–Behnken design of RSM and ANN models also indicate that the proposed models predict the responses adequately within the limits of input parameters being used. It is suggested that regression equations can be used to find optimum conditions for HI and σ of laser-hardened commercially pure titanium material. 相似文献
133.
Srinivasu P Balasubramanian VV Kumaresan L Sawant DP Jin X Alam S Ariga K Mori T Vinu A 《Journal of nanoscience and nanotechnology》2007,7(9):3250-3256
Carbon nanocage, a three dimensional cage type mesoporous carbon with very high surface area and pore volume, has been functionalized with carboxyl groups for the first time via a simple oxidation using ammonium persulfate solution (APS). The carboxyl groups functionalized carbon nanocage materials have been unambiguously characterized by various sophisticated instruments such as FT-IR, HRSEM-EDX, XRD, nitrogen adsorption, and HRTEM. The degree of carboxyl group functionalization has been controlled by the simple adjustment of the oxidation parameters such as oxidation time, APS concentration and oxidation temperature. FT-IR spectroscopy combined with the HRSEM-EDX has been used to provide a quantitative analysis of the carboxyl groups on the surface of the carbon nanocage materials before and after the APS treatment. In addition, the effect of the oxidation parameters on the structural order and the textural parameters of the carbon nanocage materials has been studied. It has been found that the role of oxidation parameters is highly critical to obtain carbon nanocage materials with a high density of carboxyl groups without affecting the structural order and the pore parameters. Thus, the reaction parameters have been carefully optimized and the best condition for the preparation of carboxyl group functionalized carbon nanocage with well-ordered structure has been proposed. 相似文献
134.
The dynamic liquid hold-up, ?LD, effective interfacial area, a, and the liquid side mass transfer coefficient kLa were determined for 0.1 m and 0.2 m multifilament wire gauze packings, 0.0125 m double walled wire gauze partition rings and 0.025 m wire gauze saddle packings in columns operated countercurrently. The theory of gas absorption accompanied by fast pseudo mth order reaction was used to determine the effective interfacial area. The values of liquid side mass transfer coefficient for the multifilament wire gauze packings were obtained by absorbing lean carbon dioxide in a buffer solution of sodium carbonate and sodium bicarbonate. KLa values for the other packings were obtained by absorbing pure carbon dioxide in tap water. The values of a and kLa for multifilament wire gauze packings were found to be two to four times higher as compared to the conventional ring or saddle packings. Further, the superficial liquid velocity was found to have marginal effect on a. The double walled wire gauze partition rings offered a values which were 1.5–2.0 times higher than that offered by 0.016 m s.s. Pall rings at low values of superficial liquid velocity (<3 × 10?3 m/s. 相似文献
135.
A new, simple, precise, and rapid ion pair reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed for the simultaneous determination of pyridoxine hydrochloride (PYR) and doxylamine succinate (DOX) in tablets. The stationary phase was a Microbondapak C18 column (10 μ, 300 mm × 3.9 mm i.d.). The mobile phase was water:methanol (60:40) containing 10 mM heptanesulfonic acid and 0.25% triethylamine and adjusted to pH 2.2 with orthophosphoric acid. Detection was carried out at 263 nm using an ultraviolet (UV) detector. The flow rate was 1.0 ml/min, and retention times were 3.65 min and 7.32 min for PYR and DOX, respectively. The linearity was obtained in the concentration range 0.5-500 μg/ml for PYR and DOX. Mean percentage recoveries were 100.20% and 101.20% for PYR and DOX, respectively. 相似文献
136.
Aparna V Shete Sudhir B Sawant Vishwas G Pangarkar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(5):526-532
Mixing parameters influencing the final particle size and conversion of zinc oxide were studied for the formation of zinc borate. Formation of zinc borate was via a fluid–solid reaction. The process was kinetically controlled above the minimum speed for particle suspension, Ns. The reaction kinetics was developed and the rate constant was estimated. Copyright © 2004 Society of Chemical Industry 相似文献
137.
138.
V K Shrikhande T Mirza B B Sawant A K Sinha G P Kothiyal 《Bulletin of Materials Science》1998,21(6):493-497
The synthesis of lead silicate glass suitable for fabrication of compression type glass to metal seals has been studied with
varying amounts of modifier ions (Na, K and Ba). A three-stage heating schedule was evolved for the preparation of glass.
While, some of the constituents were taken in the form of oxides, the others were either in the form of carbonates or nitrates.
Dependence of micro hardness of these glasses on the relative content of Na2O, K2O and BaO was investigated. The concentration of these oxides was varied in the range 0–16 wt%. The modifier ions were seen
to affect the micro hardness in a combplex manner. While the micro hardness of glass without Na2O and 13 wt% K2O was found to be 504 kg/mm2, it turned out to be 547 kg/mm2 for a glass with 13 wt% of Na2O in the absence of K2O. However, the micro hardness of the glass synthesized having optimum composition with oxides of Na, K and Ba in the proportion
of 5, 8 and 4 wt%, respectively was 455 kg/mm2. The glass powder was found to be suitable for making single- and multi-pin seals which could withstand pressures up to 1·2×104 psi and vacuum of 10−8 Torr. 相似文献
139.
S. S. Suryavanshi S. M. Kabbur U. B. Deshmukh S. R. Sawant 《Journal of Electronic Materials》2000,29(7):979-983
Compositions having the general formula Zn0.5Cu0.5−tLi2tFe2O4, where t=0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.1, have been synthesized by using coprecipitation
techniques using oxalate precursors. The initial permeability was calculated from the inductance measurements with a torroidal
core of 100 turns, using the formula L=0.0046 μi N2 h log d2/d1. There is a decrease in initial permeability (μi) with the substitution of Li1+ ions which is explained on the Globus model. The values of rotational permeability (μrk) and μw have been calculated. In all the compositions, the main contribution to the initial permeability is due to domain wall motion.
With addition of Li1+ ions the wall permeability μw decreases, which suggest that these ions cause impedance to the domain wall motion. The frequency variation of μ′ and μ″
clearly indicate the low-frequency dispersion which may be attributed to the domain wall movements. From the L.F. studies
it is concluded that the losses are minimum in the frequency region of 10 KHz to 1 MHz as expected for lithium ferrites. 相似文献
140.
The kinetics of the liquid‐phase catalytic hydrogenation of p‐chlorobenzophenone have been investigated over a 5 % Pd/C catalyst. The effects of hydrogen partial pressure (800–2200 kPa), catalyst loading (0.4–1.6 gm dm–3), p‐chlorobenzophenone concentration (0.37–1.5 mol dm–3), and temperature (303–313 K) were studied. A stirring speed > 20 rps has no effect on the initial rate of reaction. Effects of various catalysts (Pd/C, Pd/BaSO4, Pd/CaCO3, Pt/C, Raney nickel) and solvents (2‐propanol, methanol, dimethylformamide, toluene, xylene, hexane) on the hydrogenation of p‐chlorobenzophenone were also investigated. The reaction was found to be first order with respect to hydrogen partial pressure and catalyst loading, and zero order with respect to p‐chlorobenzophenone concentration. Several Langmuir‐Hinshelwood type models were considered and the experimental data fitted to a model involving reaction between adsorbed p‐chlorobenzophenone and hydrogen in the liquid phase. 相似文献