In vivo evaluation of a mucoadhesive polymeric caplet for intravaginal anti-HIV-1 delivery and development of a molecular mechanistic model for thermochemical characterization

Context and objective: The aim of this study was to develop, characterize and evaluate a mucoadhesive caplet resulting from a polymeric blend (polymeric caplet) for intravaginal anti-HIV-1 delivery.

Materials and methods: Poly(lactic-co-glycolic) acid, ethylcellulose, poly(vinylalcohol), polyacrylic acid and modified polyamide 6, 10 polymers were blended and compressed to a caplet-shaped device, with and without two model drugs 3′-azido-3′-deoxythymidine (AZT) and polystyrene sulfonate (PSS). Thermal analysis, infrared spectroscopy and microscopic analysis were carried out on the caplets employing temperature-modulated DSC (TMDSC), Fourier transform infra-red (FTIR) spectrometer and scanning electron microscope, respectively. In vitro and in vivo drug release analyses as well as the histopathological toxicity studies were carried out on the drug-loaded caplets. Furthermore, molecular mechanics (MM) simulations were carried out on the drug-loaded caplets to corroborate the experimental findings.

Results and discussion: There was a big deviation between the T_g of the polymeric caplet from the T_g's of the constituent polymers indicating a strong interaction between constituent polymers. FTIR spectroscopy confirmed the presence of specific ionic and non-ionic interactions within the caplet. A controlled near zero-order drug release was obtained for AZT (20 d) and PSS (28 d). In vivo results, i.e. the drug concentration in plasma ranged between 0.012–0.332?mg/mL and 0.009–0.256?mg/mL for AZT and PSS over 1–28 d.

Conclusion: The obtained results, which were corroborated by MM simulations, attested that the developed system has the potential for effective delivery of anti-HIV-agents.     

Management, Market, and Financial Factors Separating Winners and Losers in E-Business

There have been many successful e‐businesses as well as many failed e‐businesses. The methods and practices that were evident in the development of both surviving e‐businesses and failed ones have much to teach us. Why did some e‐businesses fail while others survived? At present few guidelines exist to assist e‐business owners and managers wanting to succeed in their Internet‐based ventures. This study empirically investigated factors that may lead to e‐business success or failure; these were categorized as management, market, and financial factors. The results of a survey were combined with one‐on‐one interviews of venture capitalists who funded successful and failed e‐businesses. The results indicate that certain factors deemed applicable to an e‐business may have contributed to the firm’s eventual success or failure.     

Effect of process parameters on impact strength of Al-7% Si alloy castings produced by VAEPC process

The castings produced by the evaporative pattern casting (EPC) process have blow holes. The blow holes in EPC castings are because of the non-escape of the gas produced as a result of burning of polystyrene pattern in the sand mold. To overcome the problem of blow holes, the EPC process is combined with the vacuum (V)- process. The vacuum applied to EPC mold draws the decomposed gases and improves the casting quality produced by the EPC process. The developed hybrid process has been termed as the vacuum assisted evaporative pattern casting (VAEPC) process. The objective of this paper to investigates the effect of process parameters, i.e, degree of vacuum, pouring temperature, grainfineness number, amplitude of vibration and time of vibration on the impact strength of Al-7% Si alloy castings in VAEPC process. In order to evaluate the effect of selected process parameters, the response surface methodology (RSM) is used to formulate a mathematical model which correlates the independent process parameters with the desired impact strength. The central composite rotatable design has been used to conduct the experiments. The results indicate that the impact strength decreases with increases in the grainfineness number and pouring temperature. Whereas, it has an inverse relationship with amplitude of vibration, time of vibration and degree of vacuum. The best value of impact strength (2.34 N/mm²) has been obtained at 400 mm Hg degree of vacuum imposed, 650°C as pouring temperature, 60 as sand grainfineness number, 460 μm as amplitude of vibration, and 70 s as time of vibration.     

Mixed waste ferrite as a novel sorbent for carbon dioxide derived from flue gases

Ferrite is a potential sorbent for flue gases such as CO₂, H₂S and SO₂. This paper discusses the adsorption and decomposition of CO₂ into carbon by hydrogen-activated waste ferrites prepared from Berkeley Pit acid mine water (Butte, MT). The decomposition effectiveness of these waste ferrites was studied at 300 °C and compared with the synthetic magnetite obtained from ferrous sulfate solution in our laboratory. The decomposition was measured by two methods: indirectly by measuring the adsorption rate of CO₂ and directly by analysing the carbon deposited on the samples. The results indicated that the mixed waste ferrite had good affinity for the adsorption and decomposition. The CO₂ decomposition data of both sorbents fitted the first-order reaction kinetics. Even though the surface area of the magnetite was higher than that of waste ferrite, the CO₂ decomposition rate of the waste ferrite was estimated to be 2.5 times higher than that of magnetite under identical conditions. The carbon analysis deposited on the sample indicated that the CO₂ was 100% decomposed into carbon and other carbon/hydrogen compounds by the waste ferrite, whereas the conversion was 43% by the magnetite. In terms of specific adsorption of carbon, ferrite was three to five times more efficient than magnetite.     

Exploiting information theory for adaptive mobility and resource management in future cellular networks

We utilize tools from information theory to develop adaptive algorithms for two key problems in cellular networks: location tracking and resource management. The use of information theory is motivated by the fundamental observation that overheads in many aspects of mobile computing can be traced to the randomness or uncertainty in an individual user's movement behavior. We present a model-independent information-theoretic approach for estimating and managing this uncertainty, and relate it to the entropy or information content of the user's movement process. Information-theoretic mobility management algorithms are very simple, yet reduce overhead by /spl sim/80 percent in simulated scenarios by optimally adapting to each individual's movement. These algorithms also allow for flexible tradeoff between location update and paging costs. Simulation results demonstrate how an information-theory-motivated resource provisioning strategy can meet QoS bounds with very small wastage of resources, thus dramatically reducing the overall blocking rate.     

Off-line quality control for V-process castings

In the present work Taguchi's approach has been applied to the V-process castings of Al-11 per cent Si alloy to acertain the most influential control factors which will provide better and consistent surface finish to the castings regardless of the noise factors present. The control factors of the V-process that may affect the quality of the castings are the molding sand, vibration frequency, vibrating time, degree of vacuum imposed, and pouring temperature. In order to understand how these factors affect the surface roughness of the V-process castings, response surface methodology has been applied, and to obtain the optimal setting of the control factors Taguchi's method has been used. It is found that the pouring temperature has a significant effect on the surface roughness of Al-11 per cent Si alloy castings made by a V-process. Thus the pouring temperature must be kept at the lower level. All other factors are insignificant. Therefore, any setting of the insignificant factors/variables that give the minimum cost can be used.     

Studies of photoconductivity in β-Apo-8′ carotenal

The photoconductive properties of a carotenoid polyene,β-Apo-8′ carotenal in polycrystalline form has been studied. The growth of the photocurrent shows an overshoot in the growth-time curve before steady state value is attained. This behaviour of photocurrent is proposed to be due to higher value of recombination coefficient than trapping coefficient. From the temperature dependence study it is observed that the steady state photocurrent, at first increases with increase of temperature, attains a maximum at a particular temperatureT _max and then decreases with temperature. TheT _max value agrees with the temperature above and below which steady state photocurrent is attained differently. Monomolecular and bimolecular recombination processes at two temperature regimes are proposed to account for the observed behaviour. The dependence of photocurrent with excitation light intensity and wavelength study provide information on the carrier generation processes. The fast decay of photocurrent have been observed at different temperatures and from this study the decay constant is calculated and it is found to be temperature independent.     

Silicon power MOSFET at low temperatures: A two-dimensional computer simulation study

Understanding how the structure of the unit-cell affects the cryogenic performance of a Si power Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is an important step toward optimizing of the device for cryogenic operations. In this paper, numerical simulations of the Si power Double Diffused MOSFET’ (DMOS) are performed at room temperature and cryogenic temperatures. Physically based models for temperature dependent silicon properties are employed in the simulations. The performances of power DMOS’ with various unit-cell structures are compared at both room temperature and low temperatures. The effect of the cell structure on the on-resistance and breakdown voltage of the device are analyzed. The simulation results suggest that the device optimized for room temperature operation can be further optimized at cryogenic temperatures.     

Evaluation of the reactivity of titanium with mould materials during casting

A methodology for evaluating the reactivity of titanium with mould materials during casting has been developed. Microhardness profiles and analysis of oxygen contamination have provided an index for evaluation of the reactivity of titanium. Microhardness profile delineates two distinct regions, one of which is characterised by a low value of hardness which is invariant with distance. The reaction products are uniformly distributed in the metal in this region. The second is characterised by a sharp decrease in microhardness with distance from the metal-mould interface. It represents a diffusion zone for solutes that dissolve into titanium from the mould. The qualitative profiles for contaminants determined by scanning electron probe microanalyser and secondary ion mass spectroscopy in the as-cast titanium were found to be similar to that of microhardness, implying that microhardness can be considered as an index of the contamination resulting from metal-mould reaction.