Surface properties of yam (Dioscorea sp.) starch powders and potential for use as binders and disintegrants in drug formulations

A comparative investigation of the surface properties of starch powders from three species of yam (Dioscorea spp.) was conducted, using corn starch BP as reference standard, with a view to assessing their usefulness as ingredients of tablets/capsule formulations.Significant differences were observed in the physicomechanical properties of the starches obtained from the various yam species. Granular diameter ranged from 5.4 μm (Chinese yam) to 34.5 μm (Round leaf yellow yam). Corn starch BP has a mean granular diameter of 12.3 μm. Chinese yam starch had the highest specific surface area (625.91 m²/kg) while Round leaf yellow yam had the lowest (117. 4 m²/kg); corn starch BP has a specific surface area of 232 m²/kg. The surface tension of the starch mucilage also varied significantly with Bitter yam having the lowest (44.56 mN/m) and Round leaf yellow yam the highest (54.00 mN/m); corn starch had a surface tension of 62 mN/m. X-ray powder diffraction revealed three distinct crystalline patterns: Bitter yam and corn starch displayed the type A while Round leaf yellow yam and Chinese yam displayed the types B and C patterns respectively. In moisture adsorption, all the starches studied displayed monolayer adsorption profiles with rate order of moisture adsorption ranging from 0.92 mg%/h for Chinese yam to 1.07 mg%/h for Round leaf yellow yam starch.Since co-formulated materials will react or interact at the interface, the variations observed in the surface properties suggest a potential for significant botanical specie-dependent differences in performance of starch powder in formulated dosage forms.     

Experimental Study of Thermal and Flame Front Characteristics in Combustion Synthesis of Porous Ni-Ti Intermetallic Material

This article describes experimental investigation of thermal and combustion phenomena during the self-propagating combustion synthesis of Ni-Ti intermetallic materials for structural application. Ni-Ti mixture is prepared from elemental powders of Ni and Ti. The mixture is pressed into solid cylindrical samples of 1.1-cm diameter and 2-3-cm length, with initial porosity ranging from 30 to 42%. The samples are preheated to various initial temperatures and ignited from the top surface such that the flame propagates axially downward. The flame speed images are recorded with a motion camera, and the temperature profile is recorded. The flame front propagation velocity is deduced as a function of the preheat temperature and initial porosity as well as the effective thermal conductivity of the reactants.     

The effects of Phyllanthus amarus extract on corrosion and kinetics of corrosion process of aluminum in alkaline solution

The effect of the extract of Phyllanthus amarus leaves on the corrosion of aluminum in 2 M NaOH solution was studied using chemical technique. The extract acts as corrosion inhibitor, with 76% efficiency at the highest concentration in the alkaline environment and the inhibition efficiency increased with increasing concentration of the extract. The adsorption of the inhibitor on aluminum surface was in accordance with the Langmuir adsorption isotherm. A zero-order kinetics relationship with respect to aluminum was obtained with and without the extract from the kinetics treatment of the data.     

Impact of cement factory operations on air quality and human health in Ewekoro Local Government Area,South-Western Nigeria

The concentrations of pollutants associated with cement production and the effects on ambient air and community health were assessed in this study. Suspended particulates were monitored using a Negretti 1000^TM air sampler. Additionally, an Ogawa^TM sampler was employed to assess levels of selected gaseous pollutants at selected sites. To collect data on health status, a questionnaire survey was used for selected neighbouring communities and clinic records for industry workers. The data were analysed with the aid of percentage, variation test, correlation and regression statistics. Mean concentrations of particulate matter of 10?μ (74–338?μg/m³) and 2.5?μ (28–116?μg/m³) were significantly higher than permissible limits (50?μg/m³ and 10?μg/m³) within and around the production plant. At all sites, levels of sulphur dioxide (0.1–12?ppb), nitrogen dioxide (0.1–13?ppb) and carbon monoxide (0.1–1.7?ppm) were below the allowable limits for human exposure. Analysis of variance showed significant spatial variations (p?相似文献   

Towards the Creation of Healthier City Neighbourhoods for Marginalised Communities in South Africa: a Case Study of the South Durban Industrial Basin in the City of Durban

This paper critically evaluates efforts to mitigate the adverse effects of pollution on residential communities that are located next to polluting chemical industries in the South Durban Basin area, in the city of Durban, South Africa. The economic agenda ignored socio-environmental imperatives as poor residential communities and polluting chemical industries were juxtaposed, which made the area prone to environmental and health hazards. Empirical research is conducted focusing on the relations among industry, the people, housing, health and the neighbourhood built environment. The paper notes that efforts to create healthier livable city neighbourhoods in Africa, and South Africa in particular, are hampered by the superimposition of industrial capitalism over social and environmental aspects of sustainable development. In this context, the paper argues marginalised neighbourhoods need to proactively articulate their environmental concerns in ways that foster the cooperation and remedial action of other stakeholders of urban governance especially the state and private sector.     

Measurement of metal–roll interface during metal rolling using normal and oblique ultrasonic reflection

ABSTRACT

It is important to monitor the roll bite interface during metal rolling to maintain the product size and homogeneity so as to minimize the material wastage. However, the harsh nature of cold rolling makes installation of sensors in metal roll for industrial applications difficult. The present study used a novel ultrasonic measurement technique whereby an ultrasonic signal went through an external sensor layout arrangement to study the metal-roll interface. The reflection coefficient obtained from the roll-strip interface at 0° to the roll surface (normal ultrasonic measurement technique) and 19° (oblique ultrasonic measurement technique) were modelled and experimentally investigated on an instrumented pilot metal rolling mill. Variances of 6.4% and 8.8% were obtained in the reflection coefficient of the techniques from experimental and modelling approaches, respectively. This showed that both techniques could be used to study the effect of the angle of incidence wave on the reflection coefficient.     

Zinc oxide incorporating iron nanoparticles with improved conductance and capacitance properties

Iron nanoparticles were incorporated into zinc oxide powders by an in situ dispersion method. The products were fully characterized by X-ray diffractometry, diffuse reflectance, FTIR spectrophotometry and complex impedance spectroscopy. The XRD patterns agreed with that of the ZnO typical wurtzite structure, the sharp diffraction peaks indicating good crystallinity of ZnO and ZnO-Fe nanoparticles. The average particle size determined by the Scherrer equation showed an increase from 20 to 25 nm for ZnO and ZnO-Fe respectively. The UV peak positions of the modified samples shifted to a longer wavelength compared to pure ZnO, providing evidence of changes in the acceptor level induced by iron nanoparticles. The optical band gap of the samples was found to be 3.14 eV for ZnO and 3.04 eV for ZnO-Fe. The electrical properties were investigated between 273 and 413 K, at several frequencies. Besides, a detailed analysis of the impedance spectrum showed an appreciable improvement of the conductivity due to the addition of iron nanoparticles. The incorporation of Fe-NPs appears to be responsible for conductance variations, charge transfer and capacitance improvement. The above properties make these materials to be regarded as very promising electrode materials for high-efficiency energy storage.