Lack of conformity between Indian classroom furniture and student dimensions: proposed future seat/table dimensions

Children spend one-quarter of a day in school. Of this, 60-80% of time is spent in the classroom. Classroom features, such as workspace and personal space play an important role in children's growth and performance as this age marks the period of anatomical, physiological and psychological developments. Since the classroom is an influential part of a student's life the present study focused on classroom furniture in relation to students' workspace and personal space requirements and standards and was conducted in five schools at Mumbai, India. Dimensions of 104 items of furniture (chairs and desks) were measured as were 42 anthropometric dimensions of 225 students from grade six to grade nine (age: 10-14 years). Questionnaire responses of 292 students regarding the perceived adequacy of their classroom furniture were collected. Results indicated that the seat and desk heights (450 mm, 757 mm respectively) were higher than the comparable students' anthropometric dimensions and that of the recommendations of Bureau of Indian Standards (BIS) (340 + 3 mm, 380 + 3 mm seat-heights, 580 + 3 mm 640 + 3 mm desk-heights) as well as Time-Saver Standards (TSS) (381.0 mm seat-height and 660.4 mm desk-height). The depth of the seats and the desks (299 mm, 319 mm, respectively) were less than comparable students' anthropometric dimensions and the recommendations of BIS (IS 4837: 1990). Students reported discomfort in shoulder, wrist, knee and ankle regions. Based on the students' anthropometric data, proposed future designs with fixed table-heights and adjustable seat-heights along with footrests were identified.     

Modeling the effects of hydroxypropylcellulose in acetaminophen tablet formulation

The objective of the research described here was to develop a set of predictive models that would be used to show the performance of hydroxypropylcellulose as a pharmaceutical tablet binder. A statistically designed set of experiments was used to relate tablet formulation to functionality. It was found that the binder level affected both hardness and dissolution time. Useful predictive models were generated for tablet hardness and dissolution time as a function of the binder or binder-drug ratio. The optimal formulation can be predicted from this study, and will depend upon the combination of desired hardness and the dissolution time for a particular drug.     

Adsorption of nickel by lignite

Process feasibility studies have been initiated to determine the possibilities of extracting metallic nickel by the lignite-adsorption route. Lignite proved to be a very effective adsorbent. Observations relating the adsorption of nickel by lignite to process variables are reported in this paper.     

Decision-feedback equalization via separating hyperplanes

The design of finite-length decision-feedback equalization (DFE) forward and feedback filters under the assumption of genie-aided feedback and independent and equally likely transmitted symbols is considered. It is shown that the problem of determining DFE filters that minimize the probability of symbol error at high signal-to-noise ratio (SNR) is equivalent to finding the hyperplane that maximally separates two given finite groups of points in a finite-dimensional Euclidean space. The latter task can be formulated as a quadratic program which is readily solved numerically. It is also shown that the problem of finding finite-length DFE filters that minimize the probability of symbol error at any SNR subject to a certain separation condition is a convex optimization problem. The case where the transmitted data is coded using a runlength-limited code is also investigated. Examples show that this criterion yields a performance that is better than zero-forcing DFE on severely distorted channels at high SNR     

Single cell extraction of zinc and manganese dioxide from zinc sulphide concentrate and manganese ores

The hydrometallurgical processing of zinc sulphide concentrates with sulphuric acid in the presence of manganese dioxide (manganese ore has been employed) and subsequent electrolytic co-deposition of cathodic zinc metal and anodic manganese dioxide is described.The influence of various parameters on the reaction

$\text{ZnS + MnO}{}_2\text{+ 2H}{}_2\text{SO}{}_4\text{= ZnSO}{}_4\text{+ MnSO}{}_4\text{+ S}{}^0\text{+ 2H}{}_2\text{O}$

has been studied. Optimum conditions for rapid and efficient reaction have been determined.The simultaneous electrowinning of zinc at the cathode and γ-MnO₂ at the anode from the leach liquor was studied. The effects of variation of current density, temperature, electrolyte composition etc. have been described in detail. During leaching 99% extraction of zinc, 98% of manganese, and 96% liberation of elemental sulphur was achieved. 80–90% anodic and cathodic current efficiencies can be obtained under optimum conditions with impurity levels of only a trace of manganese in the zinc deposit and vice-versa.The anodically deposited manganese dioxide was the γ-battery active variety and was found to be satisfactory.The results indicate the potential for the development of a technique for zinc and manganese dioxide production in a single cell.     

Halophilic class I aldolase and glyceraldehyde-3-phosphate dehydrogenase: some salt-dependent structural features

Aldolase and glyceraldehyde-3-phosphate dehydrogenase from the extremely halophilic archaebacterium Haloarcula vallismortis are stable only in high concentrations of KCl present within the physiological environment. Data concerning the structural changes in the two enzymes as a result of lowering of salt concentration and changes in pH were obtained by monitoring the intrinsic protein fluorescence in the presence of quenchers. When the KCl concentrations were lowered below 2 M or in the presence of 6 M guanidine hydrochloride, the emission maximum shifted to a longer wavelength, indicating enhanced exposure of tryptophyl residues to the solvent. The spectral characteristics of the two proteins in guanidine hydrochloride and 0.4 M KCl were identical. However, these denatured states appear to be different than those observed after acid denaturation. Further perturbation of fluorescence was observed due to I-, and application of the Stern-Volmer law showed that the total fluorescence was available to the quenchers only in 0.4 M KCl solutions. The unfolding of proteins in 0.4 M KCl was a gradual process which was accompanied by a time-dependent loss in enzyme activity. The activity loss was complete within 30 min for aldolase whereas in the case of GAPDH nearly 3 h was required for the destruction of activity. For both enzymes, inactivation and protein denaturation were strongly correlated. The data on activity and thermostability measurements of the two enzymes in varying concentrations of KCl and potassium phosphate revealed that though both proteins are halophilic, the forces in the maintenance of their stability could be different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adsorption of cobalt by lignite

Studies similar to earlier ones which had established the feasibility of extracting nickel by the lignite adsorption route were conducted on the adsorption extraction of cobalt on lignite, and with equal success.Optimal values of variables such as pH, sorbent/sorbate ratio, adsorbent particle size, contact time, temperature, and the effect of excess ammonium carbonate were evaluated.The rate of adsorption of cobalt was found to be slower than that for nickel. However, the recovery of over 99% cobalt from ammoniacal carbonate solutions, at optimal conditions, was comparable to that for nickel.The cobalt was recoverable as metal, by ignition of the loaded lignite, or in solution, by elution with sulfuric acid in single or multiple stages.