In this study hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaCMC) were used as polymeric carriers to improve controlled release performances of matrix tablets containing a ...soluble drug. The drug release behaviour of the systems containing these two polymers mixture and each material separately was investigated. To evaluate the effect of the dissolution medium pH, on the drug release performance, release tests were conducted at pH 1, 4.5 and 6.8. In vitro release studies demonstrated that the mixture of the two cellulose derivatives enables a better control of the drug release profiles at pH 4.5 and at 6.8 both in term of rate and mechanism. Texture analysis on the swollen tablets helps to understand drug release kinetic and mechanism. In fact, the results obtained confirm that a gel, which is characterized by high strength and consistence is less susceptible to erosion and chains disentanglement and the drug release mechanism is mainly governed by diffusion. On the contrary, gels, which show a low strength and texture, have low resistance to the fluid erosion action and the release of the active molecule is manly due to polymer relaxation and chains disentanglement moving the drug delivery kinetic towards an erosion/relaxation mechanism.
Water, Na, K, and Cl balances, blood plasma composition, and urine and fecal outputs were studied in 5 high yielding cows (>30 kg/d milk) at 2 wk prepartum and at 2 and 7 wk postpartum during the ...summer in Israel. Cows were fed complete diets with electrolyte content exceeding dietary recommendations. Plasma volume, as assessed by hematocrit changes, was greater postpartum, probably due to increased heat load and water turnover. Milk secretion markedly increased electrolyte output, which was compensated for only partially by increased intake. This was associated with marked reduction of electrolyte losses in excreta, particularly that of Na and Cl. On the basis of urea excreted in the urine, it seems that the current practice of abruptly increasing protein content of the diet at the onset of lactation might reduce the efficiency of dietary protein utilization, compared with efficiency of protein utilization at a later stage of lactation. The need to excrete excessive N also adversely affected the water and electrolyte balances. At initiation of lactation, when DMI is still limited and hot weather obstructs its rapid increase, the current recommendations for electrolytes as a percentage of the ration do not meet the needs.
Background: Appearance or aesthetics play an important role in the lives of most people specially professionals and any restorations with less than optimal aesthetics will probably not acceptable. ...Dental implants have earned an excellent reputation for Biocompatibility, Predictability and function throughout the past decades. Use of angulated abutments may be the method of choice when anatomic limitations preclude the axial placement of an implant. A variety of pre angled abutments are available at specific divergence angles, additionally, custom angled abutments may be cast to profile necessary for an acceptable prosthetic outcome. Objectives: The purpose of this study was to evaluate and compare the stress distribution around the vertical (0 degree) and angled (15, 20 degree) abutments in implants. This study was carried out under a vertical force of 100 N and horizontal force of 50 N respectively for all the situations. Materials & Methods: A 3D finite element model was made of anterior maxillary right canine region using the details from the CT scan using the computer software (ANSYS 11). A stimulated 13 × 4.2 mm implant was placed in the centre of the b one and its superstructure was created. Two different loading conditions for 3 different abutment angulations (0, 15, & 20 degree) relative to long axis of implant were applied. The stress generated in the cortical and cancellous bone around the implant was recorded and evaluated with the help of ANSYS. Resuts: It was shown that on vertical loading and horizontal loading of 100 N and 50 N respectively on zero degree angulated abutment, the Von Mises stresses were seen to be uniformly distributed all along the implants in the cortical and cancellous bone. It was also shown that vertical and horizontal loading of 100N and 50 N respectively produced maximum stresses n both cortical and cancellous bone around the neck of Implant for both the 15 degree and 20 degree angulated abutments. Conclusion: the zero degree produced the least amount of stress so as far as possible the Implants should be placed along the axial loading directions of the proposed prosthesis.
Many luminous blazars which are associated with quasar-type active galactic nuclei display broadband spectra characterized by a large luminosity ratio of their high-energy ( Delta *g-ray) and ...low-energy (synchrotron) spectral components. This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition. Luminous blazars also typically have very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high-energy blazar emission. As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad-line region, or dusty molecular torus. The lack or weakness of bulk-Compton and Klein-Nishina features indicated by the presently available data favors the production of Delta *g-rays via upscattering of infrared photons from hot dust. This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows. This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical, and Delta *g-ray frequencies. We also propose that the parsec-scale blazar activity can be occasionally accompanied by dissipative events taking place at sub-parsec distances and powered by internal shocks and/or reconnection of magnetic fields. These could account for the multiwavelength intraday flares occasionally observed in powerful blazar sources.
We model the mass distribution of long gamma-ray burst (GRB) host galaxies given recent results suggesting that GRBs occur in low-metallicity environments. By utilizing measurements of the redshift ...evolution of the mass-metallicity relationship for galaxies, along with a sharp host metallicity cutoff suggested by Modjaz and collaborators, we estimate an upper limit on the stellar mass of a galaxy that can efficiently produce a GRB as a function of redshift. By employing consistent abundance indicators, we find that subsolar metallicity cutoffs effectively limit GRBs to low-stellar mass spirals and dwarf galaxies at low redshift. At higher redshifts, as the average metallicity of galaxies in the Universe falls, the mass range of galaxies capable of hosting a GRB broadens, with an upper bound approaching the mass of even the largest spiral galaxies. We compare these predicted limits to the growing number of published GRB host masses and find that extremely low-metallicity cutoffs of 0.1 to 0.5 Z are effectively ruled out by a large number of intermediate mass galaxies at low redshift. A mass function that includes a smooth decrease in the efficiency of producing GRBs in galaxies of metallicity above 12+log(O/H)KK04 = 8.7 can, however, accommodate a majority of the measured host galaxy masses. We find that at z ~ 1, the peak in the observed GRB host mass distribution is inconsistent with the expected peak in the mass of galaxies harboring most of the star formation. This suggests that GRBs are metallicity-biased tracers of star formation at low and intermediate redshifts, although our model predicts that this bias should disappear at higher redshifts due to the evolving metallicity content of the universe.
Low temperature plasma processing for cell growth inspired carbon thin films fabrication Kumar, Manish; Jin Xiang PiaoauthorCenter for Advanced Plasma Surface Technology, NU-SKKU Joint Institute for Plasma-Nano Materials, School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, 440-746, South Korea; Su Bong JinauthorCenter for Advanced Plasma Surface Technology, NU-SKKU Joint Institute for Plasma-Nano Materials, School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, 440-746, South Korea ...
2015
Journal Article
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