Nuclear Magnetic Resonance Analysis of Phenytoin and Sodium Phenytoin in Solid Dosage Forms

A rapid and specific nuclear magnetic resonance (NMR) spectroscopic method was developed for determining phenytoin and its sodium salt in capsules and tablets. Acetamide was used as the internal standard and 0.5% sodium deuteroxide in deuterium oxide served as the NMR solvent. The concentration of drug per unit dose was calculated from the integration values for the resonance signals of phenytoin at about 7.40 ppm and of the internal standard at about 1.97 ppm. The average recovery value of phenytoin added to synthetic samples, in concentrations ranging from 84 to 122 mg, was 99.9 ± 0.2% (SD) with a coefficient of variation of 0.2%. The method using commercial products gave results comparable to those obtained by the titrimetric and gravimetric methods of USP XX. Excipients of tablets and capsules such as sucrose and lactose did not interfere with the determinations. The proposed method was found suitable for measuring the content uniformity of capsules and tablets, and offered a positive means of identification on phenytoin in these dosage forms.     

Cervical orthoses effect on cervical spine motion: roentgenographic and goniometric method of study

Movement of the cervical spine in the sagittal plane was studied in ten normal subjects from 20 to 30 years of age without and with four different cervical orthoses: (1) polyethylene Camp plastic collar with chin and occiput piece, (2) plastizote Philadelphia collar, (3) four-poster and (4) SOMI (sternal occipital mandibular immobilization). The effect of the orthoses on restricting sagittal motion was measured simultaneously using roentgenographic and bubble goniometric methods. The subject was immobilized in a straight back chair to eliminate trunk motion, and lateral cervical spine films were taken of each subject in neutral, flexion and extension without and with each orthotic device. Distortion forces exerted on the orthotic devices were standardized by measurement of pressures at the chin and occiput. Roentgenographic measurements of flexion and extension and anteroposterior displacement of the cervical spine were compared to the measurements obtained by bubble goniometry. The four-poster and SOMI were found to be most effective in restricting extension and flexion respectively. The polyethylene and plastizote orthoses were significantly less effective in restricting motion. The bubble goniometer is an adequate clinical tool in assessing overall flexion-extension of the cervical spine but is not so precise and does not give information on the degree of motion at an individual vertebral level.     

Hydration of dibarium silicate II. rate of hydration

The rate of hydration of dibarium silicate (Ba²SiO₄) in paste form at room temperature was investigated. The uncombined barium hydroxide produced in the reaction, determined by a modified Franke method, was used as a measure of the extent of hydration. The linear relationship obtained between the uncombined barium hydroxide and the chemically combined water confirms that similar hydration products are formed at all stages of hydration, and either may be used as a measure of the degree of hydration. The rate of hydration of dibarium silicate was found to be lower than that of tricalcium aluminate, but higher than those of alite, tricalcium silicate and β-dicalcium silicate. The effect of water/solid ratio on the rate of hydration was also investigated. Dibarium silicate was completely hydrated after 30 days when it was mixed with a water/solid weight ratio > 0.7:1.     

Room-Temperature Mid-, and Far-Infrared Absorption and Electrical Properties of Intercalated GaSe and TlInS<Subscript>2</Subscript> Crystals

We report room-temperature measurements of the mid- and far-IR absorption throughout the 400 – 4000 cm^?1 and 10 – 700 cm^?1 spectral ranges and the resistivity of layered p-GaSe and p-TlInS2 intercalated with Li⁺. Intercalation was performed by immersing Bridgman grown crystals in 0.5 M solutions of LiCl in distilled water at ambient conditions. The crystal structure and the stoichiometry of the grown crystals were determined by X-ray diffraction and XRF methods. It is shown that intercalation does not change the frequency of the IR-, and Raman active low-frequency“rigid layer” mode (GaSe), the space symmetry group or the lattice parameters of the crystals. It was found that for both crystals, the resistivity versus time dependencies are nearly the same. Three ranges in the resistivity-intercalation time dependencies were explained qualitatively. The resistivity increase due to intercalation was explained by assuming that the intercalated lithium ions act as ionized donors and compensate the host p-type crystal. The highest degree of compensation for GaSe and TlInS₂ crystals was achieved after intercalation during 12 and 10 days, respectively.     

TURBULENT HEAT TRANSFER IN A CIRCULAR TUBE WITH VISCOUS DISSIPATION

The problem of developed turbulent conveclive heat transfer with viscous dissipation is considered for flow in a circular tube. Two cases are considered, Prandtl number equal to unity and large Prandtl number. For Prandtl number equal to unity, an exact expression for the recovery factor is presented which accounts for the radial variation in velocity profile. This exact expression is evaluated using the turbulent logarithmic velocity distribution. For large Prandtl numbers, a general asymptotic expansion for the recovery factor is determined which includes both wall and core contributions. A comparison of these results suggests that the large Prandtl number formula found for the recovery factor should be accurate for all Prandtl numbers greater than about unity.     

Sexual intimacy in psychology training: Results and implications of a national survey.

In a nationwide survey of members of American Psychological Association Division 29 (Psychotherapy), which had a 48% return rate (N=481), 10% of the respondents reported sexual contact as students with their educators; 13% reported entering sexual relationships as educators with their students. However, only 2% believed that such relationships could be beneficial to trainees and educators. Gender differences were significant: 16.5% of the women, compared with 3% of the men, reported sexual contact as students; however, 19% of the men, compared with 8% of the women, reported such contact as psychology educators; and 12% of the males, compared with 3% of the females, reported sexual contact as psychotherapists with their clients. Sexual contact in psychology training programs seems to be increasing: 25% of the recent female graduates had had sexual contact, compared with only 5% of those with degrees for more than 21 yrs. The literature on ethics, standards, research, theory, and practice leaves both psychology graduate students and those psychologists responsible for their education without clear expectations, information, or guidelines concerning sexual intimacy in psychology training. This article represents an attempt to raise the issue and to present some initial information. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Astigmatic Gaussian beams produced by axially asymmetric laser cavities

Gaussian beams generated within astigmatic resonators are themselves astigmatic, having wavefront curvatures and spot sizes that are different when measured in two orthogonal directions. Expressions are derived for the confocal parameters, spot sizes, waist positions, and stability conditions of beams formed within spherical mirror resonators that contain one or more inclined plates (or Brewster-ended laser rods). An expression is also derived for the resonant frequencies of the TEMmnmode in such a resonator. It is shown that the frequency degeneracy between modes of the samem + nis lifted and the frequency splittings are calculated. The astigmatism produced by prisms used for dispersion is also considered and precautions are described for avoiding serious astigmatism in resonators containing such prisms.     

Bioactive glass scaffolds for bone regeneration and their hierarchical characterisation

Scaffolds are needed that can act as temporary templates for bone regeneration and actively stimulate vascularized bone growth so that bone grafting is no longer necessary. To achieve this, the scaffold must have a suitable interconnected pore network and be made of an osteogenic material. Bioactive glass is an ideal material because it rapidly bonds to bone and degrades over time, releasing soluble silica and calcium ions that are thought to stimulate osteoprogenitor cells. Melt-derived bioactive glasses, such as the original Bioglass composition, are available commercially, but porous scaffolds have been difficult to produce because Bioglass and similar compositions crystallize on sintering. Sol-gel foam scaffolds have been developed that avoid this problem. They have a hierarchical pore structure comprising interconnected macropores, with interconnect diameters in excess of the 100 microm that is thought to be needed for vascularized bone ingrowth, and an inherent nanoporosity of interconnected mesopores (2-50 nm) which is beneficial for the attachment of osteoprogenitor cells. They also have a compressive strength in the range of cancellous bone. This paper describes the optimized sol-gel foaming process and illustrates the importance of optimizing the hierarchical structure from the atomic through nano, to the macro scale with respect to biological response.