A simple atomic-absorption spectrophotometry method is described for the determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys, with use of a single sample solution. The sample is dissolved in a mixture of hydrobromic acid and bromine, then fumed with sulphuric acid. The lead sulphate is dissolved in concentrated hydrochloric acid. The method is particularly suitable for the determination of silver and bismuth, which are co-precipitated with lead sulphate. The other elements can also be determined after removal of the lead sulphate by filtration.
The association of arsenical poisoning with the development of skin cancer is well-known. In Malaysia, arsenic has been shown to coexist with tin in tin-mining land. Our preliminary investigation has shown that the level of arsenic in well water from a tin-mining area is high. We report 3 patients with cutaneous lesions typical of chronic arsenical poisoning such as hyperpigmentation, keratoses and skin cancer. These patients have positive histories of previous domicility in tin-mining areas. We conclude that these patients developed chronic arsenical poisoning from drinking well water polluted with arsenic from the tin-mining soil.
The usefulness of peripheral human lymphocytes as a bioindicator for ionizing radiation effect was tested in a survey of Malaysian workers in two industries producing technologically enhanced naturally occurring radioactive material (TENORM). Workers in amang processing plants who have been with the plant for an average of 12.9 years and who were exposed to radioactive dust showed significantly higher frequencies of chromosomal aberration compared to control and even ilmenite-processing workers. Such frequency was not significantly different between workers in ilmenite-processing plant and control. The differences in duration of employment, occupational hygiene, together with the difference in the percentage of 'old' and 'new' aberrations among the groups sampled were used to explain the high chromosomal aberration frequency among amang workers. The presence of significantly high chromosome damage (dicentrics and fragments) in workers who were chronically exposed to doses below 50 mSv per year or 20 mSv per year averaged over 5 years (ICRP, 1991) provided additional experimental data on the dose-effect relationship at these low-dose ranges. The results confirm the usefulness of using human lymphocytes as a bioindicator for chronic exposure to ionizing radiation and in cases where physical radiation detectors are not available.
Processing of by-product heavy minerals (amang) from tin mining involves potential exposure to external and internal sources of radioactivity. The radioactivity arises through the presence of thorium and uranium series radionuclides in the various minerals. Monazite is the most radioactive mineral, containing 3% to 7% thorium by weight, while ilmenite is generally the least radioactive mineral containing typically less than 0.05% thorium. External exposure occurs when workers are in close proximity to accumulations or stockpiles of the radioactive minerals, whereas internal exposure occurs when workers are involved in dusty processes. This paper summarizes the nature of the amang industry in South East Asia and presents the results of preliminary measurements of external radiation and airborne radioactivity in twelve Malaysian and Thai plants. Although constrained by a paucity of exposure data, it is concluded that radiation doses to some amang plant workers may approach or exceed international standards and that appropriate control measures are required as a matter of priority, Radiation doses may approach or exceed 100 mSv in situations where workers are exposed to excessive levels of ambient dust and no protective measures are used. Observations and recommendations are made relating to monitoring and surveillance, instruction and training, and engineering and administrative protection measures.
Matched MeSH terms: Air Pollutants, Radioactive/analysis; Radiation Monitoring; Tin*; United Nations; Occupational Exposure*
Organostannum(IV) complexes derived from dicarboxylic acids have been successfully synthesised from triphenylstannum(IV) hydroxide (Ph3SnOH). The complexes were obtained by refluxing Ph3SnOH and the respective dicarboxylic acids (malonic, succinic, glutaric and adipic acids) using a Dean and Stark apparatus in the appropriate solvent. The free ligands and complexes were characterised by C, Hand Sn elemental analysis and spectroscopic methods such as infrared and nuclear magnetic resonance (1H, 13C NMR). Structure determination of triphenylstannum(IV) succinate, 2, showed that each dicarboxylate anion was bonded monodentatically to two triphenylstannum(IV) moieties. The geometry surrounding each stannum atom is close to a tetrahedron. Spectroscopic data obtained for all complexes were found to be similar and thus it may be concluded that all complexes have the same structure as 2.
The DCA (Drug Control Authority), Malaysia, has implemented the phase 3 registration of traditional medicines on 1 January 1992, with special emphasis on the quality, efficacy, and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicine preparations. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation, containing Tongkat Ali, were analyzed for mercury content using cold vapor atomic absorption spectrophotometer. Results showed that 36% of the above products possessed 0.52 to 5.30 ppm of mercury and, therefore, do not comply with the quality requirement for traditional medicines in Malaysia. Out of these 36 products, 5 products that possessed 1.05 to 4.41 ppm of mercury were in fact have already registered with the DCA, Malaysia. However, the rest of the products that contain 0.52 to 5.30 ppm of mercury still have not registered with the DCA, Malaysia. Although this study showed that only 64% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to mercury, they cannot be assumed safe from mercury contamination because of batch-to-batch inconsistency.
The processing of amang, or tin tailings, for valuable minerals has been shown to technologically enhance NORM and this has stirred significant radiological safety and health concerns among Malaysia's regulatory authority. A growing radiological concern is now focused on the amang effluent containing NORM in recycling ponds, since these ponds may be reclaimed for future residential developments. A study was carried out to assess the radiological risk associated with amang processing and the accumulated effluent in the recycling ponds. Twenty-six sediment samples from the recycling ponds of two amang plants in the states of Selangor and Perak, Malaysia, were collected and analyzed. The maximum activity concentrations of (238)U, (226)Ra, (232)Th and (40)K recorded in sediments from these ponds were higher than Malaysia's and the world's natural highest. Correspondingly, the mean radium equivalent activity concentration indices, Ra(eq), and gamma radiation representative level index, I(gammar), were higher than the world's average. The enhancement of NORM in effluent sediments as a consequence of amang processing, and the use of a closed water management recycling system created Effective Dose Rates, E (nSv h(-1)), that signal potential environmental radiological risks in these ponds, should they be reclaimed for future land use.
Electrodeposition of white copper-tin alloys (including white miralloys) has been done onto planar mild steel substrates from alkaline cyanide solutions at 65 0 C. The chemical composition of the coating is influenced by plating bath composition and current density. White miralloy can be produced from the test solution containing 10 g/l CuCN2 - , 45 g/l Na2SnO3, 25 g/l NaCN, and 12 g/l NaOH at current density about 5 mA/cm 2 . The local compositions of the coating cross section were analyzed using EDX installed in a FESEM operated at an accelerating voltage of 20 kV. The phases formed during co-deposition process were identified using XRD at 25 mA current and 35 kV voltage.
The paper looks into the possibility of using standard addition method to analyse uranium and thorium in tin slag. Tin slag samples obtained from Butterworth was grind to 180 ȝm and injected with different concentrations of uranium and thorium. Linear calibration graphs were obtained for both these samples with R 2 values for uranium and thorium as 0.9989 and 0.9915 respectively. Based on this graphs, the initial uranium and thorium in the tin slag sample was established as 60 ppm for uranium and 160 ppm for thorium.
Tin slag was collected from a slag dump in the Penang Island and was analysed for its elemental composition using microfocus XRF with a 300ȝm x-ray spot diameter. The tin slag sample was analysed direct without any sample treatment and analysis was conduct on four different spots. The result gives different elemental composition on these different spots. Among the elements analysed are Al2O3, SiO2, SnO2, CaO, TiO2, Nd2O3, MnO, Fe2O3, TaO, W2O3, As2O3, ThO2, U3O8, ZrO2 and Nb2O5. Elemental mapping was also done to show the distribution of these elements in the sample.
Self-propagating high-temperature synthesis (SHS) of powder compacts is a novel processing technique being developed as a route for the production of engineering ceramics and other advanced materials. The process, which is also referred to as combustion synthesis, provides energy- and cost-saving advantages over the more conventional processing routes for these materials. In the case of titanium or titanium alloy materials, prior researches employed powder metallurgy technology for preparing metal matrix composites, MMCs and laminated structures through the use of fine powders of an inert phase or phases (TiC, TiN, TiB and TiB2B ) dispersed in Ti or Ti alloy powders. The present research relates to manufacture of titanium-ceramic composites that are synthesized by combustion synthesis (SHS) and retains a multilayered composite microstructure comprising one or more titanium-based layers and one ceramic titanium carbide layers.
In this study the intermetallic (IMC) thickness of Sn-Pb, Sn-Zn and Sn-Zn-Bi solders on copper (Cu) substrate were measured at different temperatures using reflow methods. Cu6Sn5 intermetallic phase was detected between Sn-Pb solder and Cu substrate. The J-Cu5Zn8 phase was detected between Sn-Zn and Sn-Zn-Bi lead-free solders with Cu substrate. The thickness of the intermetallics increases with temperature. The IMC thickness for Sn-8Zn-3Bi solder is lower than Sn-9Zn solder for all the soldering temperatures, indicating that Bi has suppressed the initial IMC formation.
Microbiological quality analysis of freshwater prawns from three sampling sites in Peninsular Malaysia viz: Site 1- Kg. Jumbang, Negri Sembilan; Site 2- Kg. Cangkat Tin, Perak and Site 3- Kg. Cenderiang, Perak for total mesophilic and psychrophilic aerobic counts, proteolytic bacterial counts, histamine producing bacteria, cadaverine producing bacteria and putrescine producing bacteria in the prawns and pond water for the three sites showed that the microbiological quality of freshwater prawns is related to the microflora of pond water in which they were grown. The initial bacterial counts indicated the values were in the range of log 4+ CFU/g for all samples. Total mesophilic and psychrophilic counts of the head regions were higher than that of the body regions for all prawn samples and types of growth media tested. All samples showed an increase in counts with time and temperature of storage up to log 7+ CFU/g for mesophilic counts after 12 hours at ambient, 6 days at 10 ± 2°C and 12 days at iced storage. The samples from Site 2 had relatively higher counts compared to the other two sites which correlated well with the levels determined in the pond water. Similar trends were observed for psychrophilic counts but at lower values for the different types of media studied.
Effects of preservatives on quality changes and shelf life of shrimp during iced storage indicated that boric acid, lactic acid and sodium metabisulphite managed to inhibit psychrophilic bacteria and biogenic amines formation in prawns while maintaining the mesophilic counts at lower levels during iced storage.
The linear and the mass attenuation coefficients of Rhizophora spp. wood in the photon energy range of 11.22 - 28.43 keV were determined. This was done by studying the attenuation of x-ray fluorescent (XRF) photons from selenium, molybdenum, silver and tin targets. Both the Kα and Kβ peaks were utilised. The results were compared with theoretical values for average breast tissues for youngage, middle-age and old-age groups calculated by using a XCOM computer programme. The mass attenuation coefficient of Rhizophora spp. was found to be close to that of the calculated young-age breast in this photon energy range.