Reaction rate oscillations during catalytic CO oxidation: A brief overview

It is not the intent here to present a comprehensive review of the dynamic behavior of the catalytic oxidation of CO. This reaction is one of the most widely studied in the field of catalysis. A review paper by Engel and Ertl has examined the basic kinetic and mechanistic aspects, and a comprehensive paper by Razon and Schmitz was recently devoted to its dynamic behavior. Those interested in further study of the subject should consult these reviews and a number of general review papers on catalytic reaction dynamics. The goal is to present a brief overview of certain interesting aspects of the dynamic behavior of this reaction and to discuss a few questions and issues, which are still the subject of study and debate

An observational study to assess the drug prescription pattern and quality of life of acne vulgaris patients in a tertiary care center in India

Background: The study was conducted to assess the prescription pattern of acne vulgaris patients, and impact of anti-acne treatment on severity of acne and change in quality of life (QoL) in patients.Methods: A prospective observational study was conducted in dermatology OPD of a tertiary care hospital with 160 patients of acne vulgaris. All patients with acne vulgaris >18 years, of either sex were included while those with pre-existing other cutaneous or systemic diseases, pregnant and lactating females and not giving consent were excluded from the study. Prescriptions were analysed and patients were followed-up at 2 and 6 weeks for assessment of change in acne severity and QoL, determined by GAGS score and CADI difference score, respectively.Results: Mean age of patients was 20.7±2.5 years, with males and females constituting 62 (38.8%) and 98 (61.3%) patients, respectively. Acne was mild in 88 (55%), moderate in 51 (31.9%) and severe in 21 (13.1%) patients. A total of 537 drugs were prescribed to all patients, with an average of 3.36 drugs per prescription. Two, 3 and 4 drugs were prescribed in 2.5%, 59.4% and 38.1% patients, respectively. There was significant improvement in the GAGS score (p<0.001) and QoL (CADI score difference) (p<0.001) at 2 and 6 weeks follow-up compared to initial visit.Conclusions:Polypharmacy was a common practice in anti-acne treatment. However, it was associated with improvement in acne severity and QoL.

Squeeze Film Damping for Aircraft Gas Turbines

Modern aircraft gas turbine engines depend heavily on squeeze film damper supports at the bearings for abatement of vibrations caused by a number of probable excitation sources. This design ultimately results in light-weight construction together with higher efficiency and reliability of engines. Many investigations have been reported during past two decades concerning the functioning of the squeeze film damper, which is simple in construction yet complex in behaviour with its non-linearity and multiplicity of variables. These are reviewed in this article to throw light on the considerations involved in the design of rotor-bearing-casing systems incorporating squeeze film dampers

Computer assisted learning vs. conventional teaching in experimental Pharmacology: perception of second year medical students

Background: The main pool of pharmacology practical teaching is formed by the use and demonstration of animal experiments. Animals have been used to demonstrate the effect of various drugs in experimental pharmacology classes, in the lab. The practical sessions in pharmacology training involving animal experiments are still taught by traditional teaching methods. Rapid development of information technology has led to newer trends in teaching and learning using Computer Assisted Learning (CAL). Keeping it in mind we decided to undertake this study to assess the perception of CAL in 2nd year MBBS students over conventional teaching in experimental pharmacology.Methods: This was an observational, questionnaire-based study. A total of hundred undergraduate MBBS (2nd year) students participated. Participants were first demonstrated an animal experiment by conventional teaching method followed by the same animal experiment demonstration on CAL. Students’ feedback was recorded on a questionnaire and analyzed.Results: The mean age of the participants was 19.88±1.28 years. The study overall observed that 62% preferred CAL to conventional (38%). Majority of the participants’ thought CAL (63%) helps to understand better over conventional (28%) and that CAL (63%) is time independent over conventional (28%). More than 85% felt that CAL was more explanatory and provided a better learning experience.Conclusions: Students preferred CAL to conventional teaching, in experimental pharmacology. It also provided insight on perception and experience of students towards CAL for experimental pharmacology. However, further studies are warranted to assess the knowledge, cognitive and psychomotor skills of students

Phase diagrams of period-4 spin chains consisting of three kinds of spins

We study a period-4 antiferromagnetic mixed quantum spin chain consisting of three kinds of spins. When the ground state is singlet, the spin magnitudes in a unit cell are arrayed as (s-t, s, s+t, s) with integer or half-odd integer s and t (0 <= t < s). The spin Hamiltonian is mapped onto a nonlinear sigma model (NLSM) in a previously developed method. The resultant NLSM includes only two independent parameters originating from four exchange constants for fixed s and t. The topological angle in the NLSM determines the gapless phase boundaries between disordered phases in the parameter space. The phase diagrams for various s and t shows rich structures. We systematically explain the phases in the singlet-cluster-solid picture.Comment: 8 pages (16 figures included

Role of Silicon in Boron Potassium Nitrate System.

To examine the possibility of improving the ignition characteristics of the commonly used pyrotechnic ignition system based on B-KNO/sub -Binder (30:70:10), B was gradually replaced by Si in its composition. The addition of Si was found to reduce the maximum pressure find increase the ignition delay. Maximum dp/dr value was observed with the composition containing 5 per cent Si. The differential thermal analysis results showed single sharp peaks for ignition in the temperature range 500-570 degreeC. The heat of combustion and burning rate decreased with increase in Si content. Impact sensitivity of the compositions increased with increase in the percentage of Si, whereas no change was observed in the friction sensitivity in comparison with the base composition

Extractive Spectrophotometric Determination of Ce(IV) with p-Anisidine

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