Stability and Dissolution Rates of Corticosteroids in Polyethylene Glycol Solid Dispersions

A study has been made to examine the stability and dissolution rates of prednisolone, prednisone and hydrocortisone formulated as solid dispersions in polyethylene glycols. Of the five PEG samples used, three enhanced the chemical instability of the steroids; the effect being dependent on the PEG sample and storage conditions of the solid dispersions. Dissolution rates of the steroids were relatively fast from the solid dispersions and showed no significant changes upon storage. Using two methods of analysis (direct UV spectrophotometry and the USP blue tetrazolium method), it is concluded that the chemical instability of the steroids in some PEG samples was due to alterations in the dihydroxy acetone side chain. One of the decomposition products found appeared to be an acidic compound resulting from oxidation of the C₁₇ side chain. The oxidation is presumably accelerated by a peroxide impurity in PEG samples.     

Anxiety as a function of intrinsic-extrinsic job orientation: The presence or absence of observers, and task difficulty.

Divided 92 intrinsically and 96 extrinsically job-oriented male undergraduates into 4 comparable subgroups. 2 subgroups worked on simple anagrams, 1 alone and 1 observed by 2 individuals of higher status. The other 2 worked on difficult anagrams under the same 2 conditions. Felt anxiety and perception of task difficulty ratings were elicited along with reactions toward the experimental conditions. The intrinsically oriented expressed more uneasiness than the extrinsically oriented while being observed on the difficult anagrams. They also tended to perceive the task as more difficult when observed than when alone, while the opposite was true for the extrinsically oriented. The importance of job orientation in the reaction to the presence or absence of os is discussed. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Penetration of household insecticides through different types of textile fabrics

Six different types of fabrics were compared for their ability to protect against human exposure to three different commercial household aerosol insecticides. Fabrics used in this investigation were, 100% cotton, cotton-polyester thermal underwear, cotton-polyester blend (twill), 100% acrylic, 100% wool and artificial silk (rayon). The household insecticides were, Black Flag (Ant and Roach Killer), Raid (Ant and Roach Killer) and Hot Shot (Wasp and Hornet Killer) containing propoxur, permethrin/pyrethrins and chlorpyrifos/allethrins as their active ingredients respectively. A fluorescent tracer, 4-methyl-7-diethyl amino coumarin was mixed with the aerosol (or equivalent aliquot) and sprayed onto cloth squares fitted on Whatman paper patches. The percentage of penetration through the cloth was quantified by the intensity of the fluorescence spectrum of each patch extract and the amount of the tracer recovered was calculated. The extract was concentrated to 1/10th of the volume to measure the content of each of the insecticides by supercritical fluid chromatography (SFC) using electron capture (ECD) and diode array detectors. Scanning electron microscope (SEM) images of the fabrics showed the geometry of the yarn. The results obtained from the fluorescence spectra, SFC and SEM showed that cotton-polyester (twill), cotton, wool and cotton thermal underwear were the least penetrable materials for the aerosols. On the other hand, acrylic and artificial silk (rayon) were the most penetrable cloth types.     

Optimal excess noise reduction in thin heterojunction Al/sub 0.6/Ga/sub 0.4/As-GaAs avalanche photodiodes

It has been recently found that the initial-energy effect, which is associated with the finite initial energy of carriers entering the multiplication region of an avalanche photodiode (APD), can be tailored to reduce the excess noise well beyond the previously known limits for thin APDs. However, the control of the initial energy of injected carriers can be difficult in practice for an APD with a single multiplication layer. In this paper, the dead-space multiplication recurrence theory is used to show that the low noise characteristics associated with the initial-energy effect can be achieved by utilizing a two-layer multiplication region. As an example, a high bandgap Al/sub 0.6/Ga/sub 0.4/As material, termed the energy-buildup layer, is used to elevate the energy of injected carriers without incurring significant multiplication events, while a second GaAs layer with a lower bandgap energy is used as the primary carrier multiplication layer. Computations show that devices can be optimally designed through judicious choice of the charge-layer width to produce excess noise factor levels that are comparable to those corresponding to homojunction APDs benefiting from a maximal initial-energy effect. A structure is presented to achieve precisely that.     

Beyond cost models: communications satellite revenue models. Integrating cost considerations into a value‐centric mindset

While satellite cost models are pervasive throughout the aerospace industry, revenue models or utility models of space systems are quasi‐inexistent. This situation perhaps conveys the false impression that satellites are either cost sinks or expensive artefacts whose value or utility profile over their design lifetime is difficult to quantify. In this paper, we propose that satellites, like any other complex engineering systems, should be perceived as value delivery artefacts, and the value delivered, or the flow of service that the spacecraft delivers over its design lifetime, deserves as much effort to quantify as the system's cost. To this effect, we build, in the case of a GEO communications satellite, revenue models based on (1) statistical analyses of spacecraft loading dynamics and (2) historical trends of market prices for the communications services provided. Results and discussions presented here should prove useful to satellite operators and industry observers. Copyright © 2006 John Wiley & Sons, Ltd.     

Ontogenesis of monoamine oxidase in the thyroid gland of rats

Mongolian gerbils (Meriones unguiculatus) were exposed to Mycobacterium paratuberculosis by intraperitoneal and oral routes. Fourteen weeks after exposure, the gerbils were necropsied and tissues were cultured and examined microscopically. Results of the study showed that gerbils can be infected with M paratuberculosis but are not suitable for studies of paratuberculosis.     

Binary image synthesis using mixed linear integer programming

Images that are to be transmitted through a distorting imaging system may be deliberately altered to compensate for that distortion. The authors consider an incoherent diffraction-limited imaging system followed by an ideal high-contrast detector that prints binary images, and seek a binary input image (a mask) that generates a desired prescribed binary output image. They have developed a method for determining the optimal binary mask by formulating the problem as a mixed linear integer program (MLIP) and using the branch and bound method to solve it.     

Low cycle fatigue of Ti-Mn alloys: Microstructural aspects of fatigue crack growth

Fatigue crack path behavior of a series of Ti-Mn alloys heat treated to produce volume fractions of the alpha phase ranging from 0 to 97.5 pct was investigated. Both Widmanstätten and equiaxed morphologies of the α phase were used in this study. Interior and surface crack paths are discussed in terms of slip behavior and microstructural details.     

Robust Parallel Algorithms for Solution of Riccati Equation

Robust and efficient parallel-vector algorithms are presented for the solution of the Riccati equations encountered in optimal control problems on shared-memory multiprocessor machines. The algorithms have been implemented on a Cray YMP 8∕8128 and applied to three large problems resulting from a continuous bridge structure, a 21-story space truss structure, and a 12-story space moment-resisting building structure. Efficiency of the algorithms is presented in terms of millions of floating point operations per second (MFLOPS) and the speedup. The MFLOPS for the largest example resulting from the 12-story space frame structure is a high 206.0. The speedup due to parallel processing only (for the same example), using seven processors, is 6.33. When vectorization is combined with parallel processing a very significant speedup of 54.4 is obtained using seven processors. The algorithms developed in this research find applications in the complex integrated control∕structural optimization problem. Further, the writers are currently using them to develop large adaptive∕smart structures.     

Study on the effect of a new construction method for a large span metro underground station in Tabriz-Iran

A method for construction of large underground spaces based on a new pre-supporting system is introduced. In this paper Mansour Station, in Line 1 of Tabriz Metro (Tabriz Urban Railway Organization, TURO); Iran has been studied using this method. Mansour Station have some special characteristics such as shallow depth, soft surrounding soil, wide span and heavy street traffic, thus requires a method of underground construction that can control the stability of the underground space and the ground settlement. This method includes a pre-supporting system that is called Concrete Arch Pre-supporting System (CAPS). Construction of CAPS is mainly based on construction method of old Iranian small water tunnels, Quanat, which is generally fast and more economical than usual methods such as forepoling. CAPS is a rib like underground structure consists of concrete piles and arch beams constructed around a proposed underground space prior to its constructions. This method has been utilized in several underground stations in Tehran Metro since 2002 and can be used for any large span underground spaces in similar ground conditions. Numerical modeling is used to simulate all the construction stages and analyze the ground behavior. The results of the modeling show that CAPS reduces the ground surface settlement and enhances the ground stability. Dimension of arch beams and their spacing has also notable effect on the ground deformation.