Optimization and Quest of HPMC loaded Stavudine Controlled Release Dosage Development by Central Composite Design utilizing Reduced Factorial Screening Technique

Abstract The current research focused on screening and finding the significant independent variables in stavudine loaded tablet, followed by optimizing the best formulation using central composite design. The objective of the study to develop stavudine loaded controlled release tablet utilizing reduced factorial design, followed by optimization technique as well as characterization of prepared tablets. Preliminary trial batches were prepared using different grades of hydroxypropyl methylcellulose. The resolution-IV reduced factorial design was selected to screen the significant independent variables in the dosage form design. A total number of eight runs were prepared and responses were recorded. The signified factors identified by half-normal and Pareto chart. The prepared tablets are evaluated for various physiochemical characterizations. Three dependent responses such as hardness, dissolution at 6 hour and 12 hours are considered in optimization process. Later on, drug-polymer interaction study was carried out. The principal of the study design based on finding the best formulation with prefixed set parameter values utilizing the concept of screening technique. It observed that HPMC K15M (57.18 %), HPMC K100 (66.32 %) and PVP K30 (7.97 %) as best composition in a formulation batch would fulfill the predetermined parameter with specific values.

Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: batch and fluidized bed reactor study

Lipase from Candida rugosa was covalently immobilized on Sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion (> 99 percent) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g-1 dry support and in a relatively short time (24 hrs) at 37°C, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2 percent yields after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale.

Optimal computer aided measure for screw internal fixation in the cavitas glenoidalis through human coracoid process of scapula / 解剖学报

Objective To investigate a special optimization technique for computer aided measure, and provide anatomical basis for screw internal fixation in the cavitas glenoidalis through the coracoid process of scapula. Methods Thirty accurate scapula models were reconstructed from CT data sets. First, special optimization objective function was designed for single screw internal fixation configuration, and the optimal placement of screw was found automatically under constraints. Then, the placements of double screws internal fixation configuration were searched taking advantage of principal component analysis. Finally, statistical measure data were provided according to new anatomical reference landmarks for clinical use. Results For single screw internal fixation configuration, the distance from the optimal screw entry point P to the acromion process point X was (39.15±2.28) mm, to the coracoid process point Y was (28.66±2.68) mm, to the angulus superior point Z was (61.13±6.57) mm;The angle was (81.27±7.15)° between PX and PY, and (133.27±6.84)° between PX and PZ. The mean inclination of the lag screw was (104.08±4.41)° for the angle with line PX, (101.29±3.51)° with line PY, and (76.23±5.03)° with line PZ. For double screws configuration, the distance from the original single screw entry point P to the screw entry point E was (5.12±1.37)mm,to the screw entry point F was (3.88±0.94)mm. The angle between the long axis of coracoid process and line EF was (27.41±3.51)°. Conclusion The automatic optimization technique for computer aided measure is very efficient and has many advantages over the conventional manual dissection methods, and is convenient to design new anatomical reference landmark system for clinical use.

IMAGE-QUALITY OPTIMIZATION FOR DUAL ENERGY COMPUTED TOMOGRAPHY (DECT) THREE-MATERIAL DECOMPOSITION / OPTIMIZACIÓN DE LA CALIDAD DE LA IMAGEN PARA LA SEPARACIÓN DE TRES MATERIALES UTILIZANDO LA TOMOGRAFÍA COMPUTARIZADA DE DOS ENERGÍAS (TCDE)

Dual energy computed tomography, which consists of the acquisition of two images of a given region of interest using two different x-ray energies, has been used to decompose images. For example, it has been proposed to estimate the degree of stenosis of blood vessels with calcified plaques. Pragmatic realities, though, such as beam hardening, scattered radiation and mostly quantum noise, reduce the ideal of a perfect decomposition. In this study, a dual energy separation method for iodinated contrast media, cortical bone and soft tissue was implemented; afterwards, it was tested in simulated noiseless and noisy situations. The noise propagation was modeled mathematically, and an image-quality optimization technique regarding the right distribution of radiation dose between the high and low energy images was proposed. The results obtained suggest that in the absence of noise and using mono-energetic beams, an accurate separation is possible, but when noise is added and poly-chromatic spectra used this decomposition becomes more challenging.

La tomografía computarizada de dos energías, que consiste en la adquisición de dos imágenes de una región de interés dada usando rayos X de dos energías distintas, ha sido utilizada para descomponer imágenes. Por ejemplo, esta técnica ha sido propuesta para estimar el grado de estenosis de vasos sanguíneos obstruidos con placas de calcio. Sin embargo, fenómenos como el endurecimiento del rayo, la radiación dispersada y principalmente el ruido cuántico, impiden que esta separación sea perfecta. En este estudio, se implementó un método de separación de medio de contraste yodado, tejido blando y hueso cortical; este se evaluó en simulaciones, tanto en presencia como en ausencia de ruido. Posteriormente, se modeló matemáticamente la propagación del ruido y, con base en los resultados de estos modelos, se propuso una técnica de optimización de la imagen basada en la distribución adecuada de la dosis de radiación entre las imágenes de energías alta y baja. Los resultados evidencian que en ausencia de ruido y con rayos mono-energéticos, es posible obtener una separación precisa, pero cuando se adiciona ruido a las imágenes y se trabaja con espectros policromáticos, la descomposición resulta más complicada.

THE OPTIMAL COMPUTER AIDED DESIGN FOR LAG SCREW INTERNAL FIXATION IN THE POSTERIOR COLUMN OF THE ACETABULUM / 解剖学报

Objective To investigate a special optimized technique for computer aided measure,and provide an anatomical basis for the placement of lag screw in the posterior column of the acetabulum. Methods Eighty accurate hemi-pelvis models were reconstructed from 40 CT data sets.The optimization objective function,for improving the placement of lag screw,was built by adaptively sampling the weighted distance of screws to the acetabulum boundary according to surgical requirements,and the two end points of the screw were modified iteratively to reduce the objective value under constraints.The statistical measure data were provided according to new anatomical reference landmarks for clinical use. Results The optimal entry point for lag screw fixation in the posterior column was located(18.90?1.19) mm above the line connecting the anterior borderline of the sacroiliac joint with the notch between the anterior superior iliac spine and the anterior inferior iliac spine,and the connecting line was divided by the perpendicular project point with a proportion of 2∶3.The mean inclination of the lag screw was(85.99?2.04)? for angle with the line connecting the entry point with the notch between the anterior superior iliac spine and the anterior inferior iliac spine,and(37.54?1.55)? for angle with the line connecting the entry point with the perpendicular project point;the mean length of the lag screws in the posterior column was(133.07?3.22)mm.Conclusion The automatic optimized technique for the computer aided measure is very efficient and has many advantages over the conventional manual dissection methods,and is convenient to design new anatomical reference landmark systems for clinical use.