An in vitro evaluation of fenugreek mucilage as a potential excipient for oral controlled-release matrix tablet

A polysaccharide mucilage derived from the seeds of fenugreek, Trigonella foenum-graceum L (family Fabaceae) was investigated for use in matrix formulations containing propranolol hydrochloride. Methocel^® hypomellose K4M was used as a standard controlled release polymer for comparison purposes. In this study the effect of lactose on the release behaviour of propranolol hydrochloride from matrices formulated to contain the fenugreek mucilage also was investigated. An increase in concentration of the mucilage in matrices resulted in a reduction in the release rate of propranolol hydrochloride comparable to that observed with hypomellose matrices. The rate of release of propranolol hydrochloride from fenugreek mucilage matrices was mainly controlled by the drug:mucilage ratio. However, the mechanism of release from matrices containing drug:mucilage ratios of 1:1, 1:1.25, 1:1.5, and 1:2 remained the same. The kinetics of release, utilising the release exponent n, showed that the values of n were between 0.46-0.57 indicating that the release from fenugreek mucilage matrices was predominantly by diffusion. The presence of lactose in matrices containing mucilage increased the release rate of propranolol hydrochloride. This is due to a reduction in tortuoisity and increased pore size of channels caused by lactose through which propranolol diffuses and therefore diffusion of water into the tablet is facilitated.     

Preparation and characterization of solid dispersions of piroxicam with hydrophilic carriers

The objective of this study was to improve the dissolution rate of a poor water soluble drug, piroxicam, by solid dispersion technique. Solid dispersions were prepared by three different methods depending on the type of carrier. The dissolution rate of piroxicam was markedly increased in solid dispersion of myrj 52, Eudragit^® E100 and mannitol. Solubility studies revealed a marked increase in the solubility of piroxicam with an increase in myrj 52 and Eudragit^® E100 concentrations. Data from the X-ray diffraction and FT-IR spectroscopy showed that piroxicam was amorphous in the solid dispersions prepared with dextrin and Eudragit^® E100.     

Investigation on a corrosion product deposit layer on a boiling water reactor fuel cladding

Recent investigations on the complex corrosion product deposits on a boiling water reactor (BWR) fuel cladding have shown that the observed layer locally presents unexpected magnetic properties. The magnetic behaviour of this layer and its axial variation on BWR fuel cladding is of interest with respect to non-destructive cladding characterization. Consequently, a cladding from a BWR was cut at elevations of 810 mm, where the layer was observed to be magnetic, and of 1810 mm where it was less magnetic. The samples were subsequently analyzed using electron probe microanalysis (EPMA), magnetic analysis and X-ray techniques (μXRF, μXRD and μXAFS).Both EPMA and μXRF have shown that the observed corrosion deposit layer which is situated on the Zircaloy corrosion layer consists mostly of 3-d elements’ oxides (Fe, Zn, Ni and Mn). The distribution of these elements within the investigated layer is rather complex and not homogeneous. The main phases identified by 2D μXRD mapping inside the layer are hematite and spinel phases with the common formula M_xFe_y(M_(1?x)Fe_(2?y))O₄, where M = Zn, Ni, Mn. It has been shown that the solid solutions of these phases were obtained with rather large differences between the parameter cell of the known spinels (ZnFe₂O₄, NiFe₂O₄ and MnFe₂O₄) and the investigated material. The comparison of EPMA with μXRD analysis shows that the ratio of Fe₂O₃/MFe₂O₄ (M = Zn, Ni, Mn) phases in the lower sample equals ～1/2 and in the higher one ～1/1 within the analyzed volume of the samples. It has been shown that this ratio, together with the thickness of the corrosion product deposit layer, effect its magnetic properties.     

Minimum Spouting Velocity of Draft Tube Conical Spouted Beds Using the Neural Network Approach

A multilayer perceptron with back‐propagation learning algorithm is developed to predict the minimum spouting velocity (u_ms) in draft tube conical spouted beds. Six dimensionless variables involving ten essential geometric and operating parameters of the beds were taken as model inputs. To compare the model results with both experimental data and those predicted by the limited existing empirical equations, the root mean square error and the mean relative error are utilized. Although there is a complex relationship between the input variables and u_ms, and despite the huge number of data available, the steps of training and testing show good agreement with the corresponding experimental values. This demonstrates that an artificial neural network is a useful approach to predict u_ms, especially when the relationship between the geometric and operating parameters and u_ms is complex and difficult to define.     

Prediction of nanofiber diameter for improvements in incorporation of multilayer electrospun nanofibers

The fabrication of novel multilayer electrospun nanofiber web is demonstrated. Under optimized processing conditions, the interface between these webs can be sustained for long time, yielding layers with distinct compartments. Simultaneous control over internal fiber architecture makes these multilayer nano-webs potential candidates for applications such as clothing and industrial filters.     

Preparation and Characterization of Solid Dispersions of Piroxicam with Hydrophilic Carriers

ABSTRACT

The objective of this study was to improve the dissolution rate of a poor water soluble drug, piroxicam, by solid dispersion technique. Solid dispersions were prepared by three different methods depending on the type of carrier. The dissolution rate of piroxicam was markedly increased in solid dispersion of myrj 52, Eudragit® E100 and mannitol. Solubility studies revealed a marked increase in the solubility of piroxicam with an increase in myrj 52 and Eudragit® E100 concentrations. Data from the X-ray diffraction and FT-IR spectroscopy showed that piroxicam was amorphous in the solid dispersions prepared with dextrin and Eudragit® E100.     

A continuous cycle solar thermal refrigeration system

A Platen-Munters refrigerator has been modified to operate with heat collected from solar energy conversion in a solar thermal continuous cycle refrigeration system. The results show that temperatures as low as −19°C are routinely achievable. The incorporation of a solar thermal battery can increase the refrigeration period to as long as 10 hours to provide cooling power for as long as 36 hours.     

CO2 laser welding of interstitial free galvanized steel sheets used in tailor welded blanks

Recently, laser welding technologies have been widely utilized to weld different automobile panels. In this research, the laser beam welding (LBW) process of interstitial free (IF) steel sheets used in the manufacturing of the car body was investigated on the basis of mathematical models. The quality indexes of LBW joints were estimated from Erichsen Cupping Test results including strength and Erichsen Cupping Index. Furthermore, three process parameters, namely laser power (P), welding speed (S), and focal position (F) were considered as the factors influencing the quality indexes. A 2.2-kW CO₂-laser beam was utilized to weld 1.2- and 0.8-mm-thick IF steel sheets. The modeling is done using experimental data which were gathered using design of experiments approach based on central composite face centered design matrix. The final regression models can be used to predict the quality indexes of laser beam-welded IF steel sheets joints at 95% confidence level. Optical metallography was utilized to characterize the weld profile and microstructures. In the second phase of this research, multi-objective genetic algorithm with the fitness function based on regression models was employed as an optimization procedure; as a result, the best quality indexes were obtained. Optimization results showed high compatibility with the actual experimental data.     

Cogrinding as an approach to enhance dissolution rate of a poorly water-soluble drug (gliclazide)

Gliclazide is practically insoluble in water. In order to improve the drug dissolution rate, cogrinding method was used as an approach to prepare gliclazide coground/solid dispersions (SDs) in the carriers such as povidone (PVP-K30), crospovidone and microcrystalline cellulose (Avicel PH 101) with different drug to carrier ratios. The dissolution rate of gliclazide from the SDs was measured at two physiological pH values of 1.2 and 7.2 simulating gastric and intestinal fluids using USP dissolution apparatus II. The concentration of the dissolved drug in the medium was determined by direct or first-derivative UV spectroscopy. The dissolution rates of the formulations were dependent on the nature and ratio of drug to carriers in SDs and the corresponding physical mixtures as well as the pH of the medium. At a higher pH the drug has a faster dissolution than at a lower pH. The fastest dissolution rates were observed from coground formulations with the drug to carrier ratio of 1:5. The amount of drug dissolved in 15 min from these SDs was varied from 96% in the case of Avicel SD to 100% for SD of PVP. Whereas the amount of drug released in the same time from unground drug powder (UD), ground drug powder (GD) and all physical mixtures was between 60 and 80%. These results indicate that the dissolution rate is highly enhanced from the SDs. DSC as well as X-ray diffraction showed reduced drug crystallinity in SDs. Scanning electron microscopy and particle size analysis revealed significant decreased particle size of the drug in SDs. FT-IR spectroscopy demonstrated no detectable interactions between the drug and carriers. In addition to latter evidence, increased wettability and hydrophilicity of drug particles and deaggregation brought about by the carriers are the reasons for enhanced drug dissolution from the SDs. One of the possible advantages of formulating an insoluble drug such as gliclazide is that if it is used in preparation of capsules or tablets of the drug, its dose might be reduced which is economically beneficial.     

Low-Frequency Noise-Based Degradation Prediction of$hboxAl_xhboxGa_1 - xhboxN/GaN$MODFETs

Degradation prediction of AlGaN/GaN MODFET is explored based on characterization of gate and drain low- frequency noise. Heterostructures grown by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) are used for this purpose. Devices from the former category were unpassivated while those of the latter were passivated. Despite the highly variable gate noise current characteristics among unpassivated MBE devices and between MBE and MOCVD-based devices, it is demonstrated that the drain noise current characteristics of the two groups of devices have considerable resemblance. Moreover, it is shown that the drain noise current level can be used as a means for gate degradation prediction