Showing papers by "National University of Malaysia published in 2000"

Band 3 mutations, renal tubular acidosis and South-East Asian ovalocytosis in Malaysia and Papua New Guinea: loss of up to 95% band 3 transport in red cells.

Abstract: We describe three mutations of the red-cell anion exchangerband 3 (AE1, SLC4A1) gene associated with distalrenal tubular acidosis (dRTA) in families from Malaysia and Papua NewGuinea: Gly(701)-->Asp (G701D), Ala(858)-->Asp(A858D) and deletion of Val(850) (DeltaV850). The mutationsA858D and DeltaV850 are novel; all three mutations seem to be restricted to South-East Asian populations. South-East Asianovalocytosis (SAO), resulting from the band 3 deletion of residues400-408, occurred in many of the families but did not itselfresult in dRTA. Compound heterozygotes of each of the dRTA mutationswith SAO all had dRTA, evidence of haemolytic anaemia and abnormal red-cell properties. The A858D mutation showed dominant inheritance and therecessive DeltaV850 and G701D mutations showed a pseudo-dominantphenotype when the transport-inactive SAO allele was also present. Red-cell and Xenopus oocyte expression studies showed that theDeltaV850 and A858D mutant proteins have greatly decreased aniontransport when present as compound heterozygotes (DeltaV850/A858D,DeltaV850/SAO or A858D/SAO). Red cells with A858D/SAO had only 3% ofthe SO(4)(2-) efflux of normal cells, thelowest anion transport activity so far reported for human red cells. The results suggest dRTA might arise by a different mechanism for eachmutation. We confirm that the G701D mutant protein has an absoluterequirement for glycophorin A for movement to the cell surface. Wesuggest that the dominant A858D mutant protein is possibly mis-targetedto an inappropriate plasma membrane domain in the renal tubular cell,and that the recessive DeltaV850 mutation might give dRTA because ofits decreased anion transport activity.

A comparison of the pattern of liver involvement in dengue hemorrhagic fever with classic dengue fever.

Abstract: The impact of dengue on liver function was studied on fifty serologically confirmed dengue cases admitted to Hospital Universiti Kebangsaan Malaysia (HUKM). Twenty-five of these patients had classic dengue fever (DF) and 25 had grade 1 or 2 dengue hemorrhagic fever (DHF). There were more (60%) DHF patients with hepatomegaly compared to DF (40%) but the difference was not statistically significant. Analysis of the liver profile showed that liver dysfunction was commoner in DHF compared to DF, indicating that the degree of liver impairment may be related to the severity of DHF. Hyperbilirubinemia was noted in 3 (12%) DHF and 2 (8%) DF patients. The mean (range) serum bilirubin was higher in DHF [14.2(5-50) micromol/l] compared to DF [10.9(5-30) micromol/l)] (p > 0.05). Elevated levels of serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were observed more frequently in DHF (20 and 12 patients respectively) compared to DF (16 and 8 patients respectively). Nine (36%) DHF and 6 (24%) DF patients had concomitant elevation of ALT and ALP levels. The mean (range) serum ALT levels were 109.3(23-325) U/l in DHF and 90.8(13-352) U/l in DF (p > 0.05). The mean (range) serum ALP levels were 102.2(15-319) U/l in DHF and 93.3(34-258) U/l in DF (p > 0.05). The ALT and ALP levels were significantly higher in DHF patients with spontaneous bleeding than those without bleeding (p < 0.05) None of the patients developed fulminant hepatitis. The immunoregulatory cells, which include the T (CD3), B (CD 19), CD4, CD8, CD5 and natural killer (NK) cells were significantly lower in DHF compared to DF patients (p < 0.05). However, the reduction in these cell counts did not correlate with the liver dysfunction seen in DHF patients. In conclusion, hepatomegaly and liver dysfunction were commoner in DHF compared to DF.

Nasopharyngeal carcinoma in Malaysian Chinese: occupational exposures to particles, formaldehyde and heat

Abstract: BACKGROUND During 1990-1992, 282 Chinese residents of Selangor and the Federal Territory, Malaysia with histologically confirmed nasopharyngeal carcinoma (NPC) were interviewed about occupational history, diet, alcohol consumption, and tobacco use, as were an equal number of Malaysian Chinese population controls, pair-matched to cases by age and sex. METHODS Exposures to 20 kinds of workplace substances, solar and industrial heat, and cigarette smoke, were analysed by univariate and multivariate methods. RESULTS Nasopharyngeal carcinoma was associated with occupational exposures to construction, metal and wood dusts; motor fuel and oil; paints and varnishes; certain other chemicals; industrial heat; solar heat from outdoor occupations; certain smokes; cigarette smoking; and childhood exposure to parental smoking. After adjustment for risk from diet and cigarette smoke, only wood dust (OR = 2.36; 95% CI : 1.33- 4.19), and industrial heat (OR = 2.21; 95% CI : 1.12-4.33) remained clearly associated. Wood dust remained statistically significant after further adjustment for social class. No significant crude or adjusted association was found between NPC and formaldehyde (adjusted OR = 0.71; 95% CI : 0.34-1.43). CONCLUSIONS This study supports previous findings that some occupational inhalants are risk factors for NPC. The statistical effect of wood dust remained substantial after adjustment for diet, cigarette smoke, and social class. Intense industrial heat emerged as a previously unreported risk factor, statistically significant even after adjustment for diet and cigarette smoke. No association was found between NPC and formaldehyde.

Resource partitioning in rhinolophoid bats revisited

Abstract: We assessed the ecomorphological structure of a guild of rhinolophoid bats in a Malaysian rainforest first described by Heller and von Helversen (1989) These authors found that the distribution of echolocation call frequencies used by 12 syntopic species was more even than expected from allometric relationships or in randomly generated communities, and that the observed minimal ratio was greater than expected by chance alone In this study we were able to expand their guild to 15 species, but in doing so it became apparent that call frequencies might be less evenly distributed across the total frequency range than previously proposed We replicated Heller and von Helversen’s (1989) analyses with the full 15-species complement but were unable to support their suggestion that rhinolophoid bats exhibit resource partitioning through differences in frequency bands We adopted a multivariate approach and incorporated measures of body size and wing morphology into the analysis We used phylogenetic autocorrelation to ensure that the species were statistically independentand principal component analysis to describe the morphological space occupied by the 15 species in the community and four additional species representing the extremes of phenotypic variation We derived interspecific Euclidean distances and tested the mean values and SDs of these distances against those of 100 guilds of ”synthetic” species created randomly within the principal component space The guild of Rhinolophoidea was not distributed randomly in multivariate space Instead we found evidence of morphological overdispersion of the most similar species, which suggests niche differentiation in response to competition Less similar species were nearer in morphological space than expected, and we suggest this is a consequence of ecological constraints on parameter combinations Despite this underdispersion, many of the more distant neighbours were evenly rather than randomly spaced or clumped in morphospace, suggesting that, given the environmental constraints on morphology, species in this guild do experience limits to their similarity Finally, we tested the influence of the relative abundance of species on morphological displacement, and found no evidence that abundant, spatially correlated species reduce interspecific overlap in morphological space

Total quality management practices in manufacturing companies in Malaysia: An exploratory analysis

Abstract: The article reviews total quality management (TQM) practices in public listed manufacturing companies in Malaysia. It also explores ISO certification of the companies as well as some other related issues. Our findings indicate that the length of TQM implementation has a significant impact on the companies' financial performance. Long - term TQM adopters are found to outperform short - term adopters. The industrial manufacturing companies exhibit higher TQM scores than the consumer manufacturing companies. In addition, the quality index ranking suggests that more stringent quality measures are being carried out in automotive and gas industries.

Palm vitamin E is comparable to α-tocopherol in maintaining bone mineral density in ovariectomised female rats

Abstract: Vitamin E has been shown to affect bone metabolism. In this study we determined the effects of palm vitamin E and alpha-tocopherol on bone metabolism. Sprague-Dawley female rats fed with normal rat chow were divided into 4 groups and supplemented with either palm vitamin E 30 mg/kg rat weight, palm vitamin E 60 mg/kg rat weight or alpha-tocopherol 30 mg/kg rat weight. One group was not supplemented. Half of these rats were ovariectomised before supplementation was given for 10 months. As expected, bone mineral density of the ovariectomised rats fed on normal rat chow diet was lower compared to the intact rats. However, these changes were not seen in the supplemented group of rats. Both intact and ovariectomised rats supplemented with palm vitamin E 30 mg/kg rat weight had a lower bone calcium content in both femoral and vertebral bones whilst rats fed palm vitamin E 60 mg/kg rat weight or alpha-tocopherol 30 mg/kg rat weight were able to maintain bone calcium content. Alkaline phosphatase activity was elevated in ovariectomised rats supplemented with palm vitamin E 30 mg/kg rat weight and alpha-tocopherol 30 mg/kg rat weight compared to the intact rats. Alpha-tocopherol also reduced the activity of tartrate-resistant acid phosphatase post-ovariectomy. These findings indicate that both palm vitamin E and alpha-tocopherol maintained bone mineral density in ovariectomised rats but caused conflicting effects on bone calcium content. Further study is needed in order to determine the mechanisms involved.

Validation of a Dietary History Questionnaire against a 7-D Weighed Record for Estimating Nutrient Intake among Rural Elderly Malays.

Abstract: Energy and nutrient intake estimated using a pre-coded dietary history questionnaire (DHQ) was compared with results obtained from a 7-d weighed intake record (WI) in a group of 37 elderly Malays residing in rural areas of Mersing District, Johor, Malaysia to determine the validity of the DHQ. The DHQ consists of a pre-coded dietary history with a qualitative food frequency questionnaire which was developed to obtain information on food intake and usual dietary habits. The 7-d WI requires subjects to weigh each food immediately before eating and to weigh any leftovers. The medians of intake from the two methods were rather similar and varied by less than 30% for every nutrient, except for vitamin C (114%). For most of the nutrients, analysis of group means using the Wilcoxon matched pairs signed rank sum test showed no significant difference between the estimation of intake from the DHQ and from the WI, with the exceptions of vitamin C and niacin. The DHQ significantly overestimated the intake of vitamin C compared to the WI (p<0.05), whilst, the intake of niacin was significantly underestimated (p<0.05). The consistency of ranking as assessed using the Spearman's rank correlation coefficient (r) was satisfactory since there were positive correlations between all of the investigated nutrients estimated using the DHQ with those assessed using the WI, except for niacin. Furthermore, both the DHQ and the WI classified approximately 38 to 62% of the subjects into the same tertile for all nutrients, except vitamin C. Therefore, the DHQ was modified by adding a checklist of foods rich in vitamin C and niacin. In conclusion, the DHQ was fairly valid for obtaining the usual intake of most nutrients, particularly on a group basis. These findings indicate that in an elderly population with a high prevalence of illiteracy, a specially designed DHQ can provide very similar estimations to that obtained from 7-d WI.

Barriers to Putting Businesses on the Internet in Malaysia

Abstract: Over fifty businesses in the Klang Valley, Malaysia that currently use e-commerce responded to a survey asking them to identify potential barriers to e-commerce expansion. The most frequently chosen categories were related to security and the uncertain nature of the legal contract between supplier and customer. Although some differences were found among certain types of companies, such concerns were generally felt by small and large companies and those with varying e-commerce experience.

Isolations of enteric pathogens from synanthropic flies trapped in downtown Kuala Lumpur.

Abstract: Four species of synanthropic flies were trapped in downtown Kuala Lumpur: Chrysomya megacephala, Chrysomya rufifacies, Musca domestica, and Musca sorbens. Burkholderia pseudomallei, the organism causing melioidosis, was the dominant bacteria isolated from Chrysomya megacephala. Klebsiella oxytoca, commonly associated with nosocomial infections, was commonly isolated from Chrysomya megacephala, Musca domestica, and Musca sorbens. Aeromonas hydrophila, the bacteria causing gastroenteritis, was predominantly isolated from Chrysomya megacephala and also from Musca domestica and Musca sorbens. A total of 18 bacterial species was isolated from the synanthropic flies trapped. Burkholderia pseudomallei had been reported for the first time.

XPS Studies of Radiation Grafted PTFE-g-polystyrene Sulfonic Acid Membranes

Abstract: Structural investigations of PTFE-g-polystyrene sulfonic acid membranes prepared by radiation grafting of styrene onto PTFE were conducted by X-ray photoelectron spectroscopy (XPS). The analyzed materials included original PTFE film as a reference material, grafted film, and sulfonated membrane samples having various degrees of grafting. Interest is focused on C1s, F1s, O1s, and S2p of narrow XPS spectra as the basic elemental components of the membrane. The original PTFE film was found to undergo structural changes in terms of chemical composition and shifting in binding energy induced by incorporation of sulfonated polystyrene grafts, and the amount of such changes depends on the degree of grafting. The atomic ratio of F/C was found to decrease with the increase in the degree of grafting, while that for S/C and O/C were found to increase.

English, identity and the Malaysian workplace

Abstract: This paper, which is an outgrowth of an ethnographic study of code and style choice in two Malaysian business organizations, explains individual and institutional choices as locally motivated pragmatic selections within the specific contexts of the workplace settings and the larger Malaysian sociolinguistic context of English as the normative choice of Malaysian business and Malay as the lingua franca. Malaysian English (ME) as the prevailing sociolect emerged as the unmarked choice in Malaysian business, rather than approximations to exonormative models, such as Standard British English, thereby challenging traditionally imposed norms of speech in Malaysian business settings which are a legacy of British rule and business links. Localized speech variation was consistently demonstrated. Sub-variants of ME spoken in ethnically distinct ways, mainly in the prosody of the native languages of the speakers, as ethnolects, together with style shifting along the full varietal range of ME, and the code-mixing of English and Malay and code-switching into Malay, were the most common ways of speaking in these settings. They voice local notions of language and communication through ethnic speech diversity in the projection of specific social and cultural personae and identities.

Screening for the In Vitro Anti-tumor-promoting Activities of Edible Plants from Malaysia

Abstract: A total of 114 methanol extracts from 42 plant families of edible Malaysian plants were screened for their inhibitory activities toward tumor promoter 12-O-hexadecanoylphorbol-13-acetate (HPA)-induced Epstein-Barr virus (EBV) activation in Raji cells. By testing at a concentration of 200 μg/ml, 74% of the 114 extracts inhibited EBV activation by 30% or more. This rate is comparable to those observed in the previous tests on edible Thai (60%) and Indonesian (71%) plants, and, importantly, much higher than that (26%) observed for Japanese edible plants. Approximately half of the Malaysian plants did not taxonomically overlap those from the other three countries, suggesting that Malaysian plants, as well as Thai and Indonesian plants, are an exclusive source of effective chemopreventive agents. Further dilution experiments indicated an extract from the leaves of Piper betle L. (Piperaceae) to be one of the most promising species. The high potential of edible Southeast Asian plants for cancer chemoprevention ...

Mating System Parameters in a Tropical Tree Species, Shorea leprosula Miq. (Dipterocarpaceae), from Malaysian Lowland Dipterocarp Forest1

Abstract: The mating system in a natural population of Shorea leprosula from Malaysian lowland dipterocarp forest was quantified by allozyme analysis using the multi-locus mixed-mating model. The population was found to be predominantly outcrossed (tm = 0.837 ± 0.066). Variation in individual multi-locus outcrossing rates (range = 0.55–1.00) may have reflected variation in individual self-compatibility, heterogeneity in the pollen pool, differences in the mating neighborhood of individuals, or population substructure. Departure from the mixed-mating model was evident from the differences in pollen and ovule allele frequencies. Pollen pool heterogeneity and significant levels of biparental mating (tm − ts = 0.127, P < 0.01) indicated that the population was most probably genetically substructured. The inbreeding coefficient based on Wright's fixation index for maternal trees (Fa = −0.078) was lower than that obtained for progenies (Fe = 0.089), suggesting considerable selection against selfed progenies duri...

Liquid natural rubber (LNR) as a compatibilizer in NR/LLDPE blends

Abstract: The effects of molecular weight of LNR, as a compatibilizer in NR/LLDPE blends, were studied. Rheological studies and mechanical properties of the blends showed that the molecular weight of LNR played a very important role in determining their performance. The blends that contained 15–25% LNR with an Mw of 4.8 × 105 and an Mn of 1.66 × 105 showed the highest mechanical properties. Outside this range of molecular weight, the compatibilizing property of LNR is no longer effective due to inhomogeneous blends. Improvements in the mechanical properties were in consonance with the increase in gel contents of the blends. The additions of LNR in the blends were able to reduce the interfacial tension; therefore, they improved the interaction between the phases of the blends. The studies also confirmed that, within the concentration range investigated, the LNR solvent did not influence the blend properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1776–1782, 2000

Genetic Diversity of a Tropical Tree Species, Shorea leprosula Miq. (Dipterocarpaceae), in Malaysia: Implications for Conservation of Genetic Resources and Tree Improvement'

Abstract: Genetic diversity and population genetic structure of Shorea leprosula was investigated using seven natural populations distributed throughout Peninsular Malaysia and one natural population from Borneo. The mean population and species level genetic diversity were exceptionally high (He = 0.369 ± 0.025 and 0.406 ± 0.070, respectively). Heterozygosity varied among populations, ranging from 0.326 to 0.400, with the highest values found in the populations from central Peninsular Malaysia. Correlations among ecological factors (longitude, latitude, and annual rainfall) were not significant (P > 0.05), indicating that these ecological variables were not responsible for the observed genetic differences among populations. The Bangi adult population exhibited a higher level of observed heterozygosity but lower fixation indices in comparison to its seedling population. All other seedling populations also showed positive fixation indices (F), indicating a general excess of homozygotes. This also may suggest...

Family influence on current smoking habits among secondary school children in Kota Bharu, Kelantan.

Abstract: Objectives: To measure the prevalence of cigarette smoking among male secondary school children and assess their family influence especially that of their fathers' smoking habits on their current smoking habits. Methodology: A cross-sectional study was carried out in Kota Bharu, Kelantan in April 1997 where 460 male form four students, aged 15 - 16 years were randomly selected from six secondary schools. Data on smoking habits, sociodemographic profile and family characteristics particularly parents and siblings' smoking habits, perceived parental supervision and communication were collected through self-administered questionnaires. Results: The prevalence of cigarette smoking among male secondary school children was 33.2%. Crude analysis shows family factors, fathers' and siblings' smoking habits, and lack of parental supervision were significantly associated with the students' current smoking habit. Among students who smoked compared to non-smokers, father's smoking habit gives a crude Odds Ratio = 1.8, 95% C.I. 1.08 - 3.16. Further analysis shows that the effect of their father's smoking habit on the student's current smoking habit is still significant after controlling for other familial and non-familial factors including parental supervision, academic performance, reported influence of cigarette advertisement, having friends who smoked and the student's poor knowledge of the ill-effects of smoking and other factors (Odds Ratio = 1.9, 95% C.I 1.05 - 3.32). In conclusion, family factors especially the father's smoking habit is an important factor that influences a student's current smoking habit and the presence of negative role models within the home need to be seriously considered in any cigarette smoking prevention programs among secondary school adolescents.

The Records Life Cycle: an inadequate concept for technology-generated records:

Abstract: The concept of a life cycle is at the core of most records management programmes. The activities of records management programmes are developed upon this concept, which has several phases that expl...

A prospective study of cantilever resin-bonded bridges: an initial report.

Abstract: A prospective study was undertaken in a dental teaching hospital to compare the clinical performance of cantilever resin-bonded bridges with a fixed-fixed design for the replacement of a maxillary permanent incisor. A total of 25 anterior resin-bonded bridges was placed in 24 patients. The prostheses were evaluated over 14 to 45 months. During the evaluation period only one fixed-fixed type debonded, which was subsequently rebonded successfully. There was no debond in the cantilever group. The short-term, initial findings showed that cantilever resin-bonded bridges performed as successfully as their fixed-fixed counterparts and were considered to be an acceptable form of restoration.

Computer Technology In Malaysia: Teachers' Background Characteristics, Attitudes and Concerns

Abstract: Providing latest computer technology, good facilities and training for teachers to use computers effectively in their classroom instruction is not sufficient. There are many other factors that need to be examined in order to ensure that teachers will use computer technology effectively in their classroom instruction. The main purpose of this study is to find out factors such as teacher?s background characteristics, attitudes and concerns that relate to teachers? use of computer technology in their teaching. This study also attempted to discover whether teachers can be grouped based on their perceptions on the use of computers. This paper will also focus on the differences among teachers who used computer technology in their classroom practice. The results of the study showed that these factors that is teachers? background characteristics, attitudes and concerns showed a great significance in the degree of classroom computer usage.

One‐Step Synthesis of K+‐Selective Methacrylic‐Acrylic Copolymers Containing Grafted Ionophore and Requiring No Plasticizer

Abstract: A main drawback in the application of ion sensors that are based on plasticized polymeric membranes is the problem of leaching of plasticizer and ionophore. Leaching problems can be critical in solid-state minidevices, e.g., ion-selective electrodes or optodes, where a thin ion sensing polymer film is often empolyed. To resolve such problems, we have designed simple methacrylic-acrylic copolymers that required no plasticizer and which include immobilized polymerizable but hydrophilic ionophores such as 4-acryloylamidobenzo-15-crown-5 (AAB15C5) and 4-acryloylamidobenzo-18-crown-6 (AAB18C6) that would normally be susceptible to leaching from plasticized PVC membranes, were used as model ionophores for the immobilization studies. These crown compounds are attractive since they can be employed as a monomeric unit in the copolymer recipe and thus no additional synthesis or polymer modification is required. Copolymers suitable for ion-selective membrane application were synthesized by introducing more than 80 wt. % of n-butyl acrylate to yield copolymers of Tg's between –20 to –30 °C. The molecular weight distributions of these copolymers were M¯w <50 000 Da and they contained 2 to 6 wt. % of immobilized crown ether ionophores. The ‘self-plasticising’ methacrylic-acrylic membranes formed with these acryloyl crown ethers demonstrated good potentiometric responses to potassium ion. In contrast, AAB15C5 and AAB18C6 entrapped in membranes in a more classical ion selective membrane recipe, even when a plasticizer was included, were still inferior in their response to those with membranes containing immobilized ionophores. The restricted mobility of the immobilized ionophores in these self-plasticizing polymer matrices did not appear to hinder the normal complexation behavior of these ionophores. This was inferred from the possible formation of the usual 2:1 and 1:1 ionophore-cation complexes of AAB15C5 and AAB18C6, respectively, in these new copolymer matrices.

Food intakes and habits of rural elderly Malays

Abstract: A cross-sectional nutritional survey was carried out on 350 elderly Malays aged 60 and above from 11 randomly selected villages in a rural area on the east coast of Malaysia. The findings indicated that the mean intakes of energy and of all of the nutrients investigated were below the Malaysian Recommended Dietary Allowances, except for protein and vitamin C. With respect to dietary habits, almost all of the subjects reported that they had breakfast (99.3%), lunch (97.9%) and dinner (90.4%) daily or almost daily (5‐6 times/week). However, approximately half of the subjects, especially women, had particular beliefs and prohibitions about specific foods. Most of the subjects usually ate their meals at home, particularly dinner, with 99.3% always having dinner in their own home. Thus, although the rural elderly Malays studied had regular meal intakes, the dietary intake was inadequate. There is a need to plan community-based intervention programmes in order to prevent the subsequent consequences of malnutrition that lead to increased morbidity and mortality.

Development of zero ODP rigid polyurethane foam from RBD palm kernel oil

Abstract: In recent years, the use of renewable resources has attracted the attention of many technologists as potential substitutes for petrochemicals, mainly from forest products. Palmeri oil, vernonia oil, castor oil and recently the cardanol oil are naturally synthesized with multiple functionality and are a new source of renewable resources which have a very bright future as an alternative to petroleum feedstock [1–3]. Since the invention of polyurethane by Bayer in 1937, the utilization of polyurethane is ubiquitous. Polyurethanes are block copolymers containing blocks of low molecular weight polyesters or polyethers covalently bonded by a urethane group (-NHCO=O). These polymers are synthesized by reacting three basic components consisting of polyisocyanate, polyhydroxyl-containing polymer (i.e. polyester or polyether polyols) and a chain extender, which is usually low molecular weight diols or diamines (i.e. 1,4-butanediol or 1,4-dibutylamine) [4]. Currently, there is a wide range of polyisocyanates, polyols and chain extenders commercially available and this has led to almost unlimited possibilities for polyurethane materials. Because of the inherent versatility on polyurethane syntheses, the properties of this class of polymers can be easily engineered to suit the applications required. Palm kernel oil is the focus of this study because it is available in abundance in Asia, especially Malaysia. In addition, it is produced from the production of palm fruit as much as 3.8 tons per hectare per annum [5], as well as offering very low market price. In this study, the RBD (refined-bleached-deodorized) palm kernel oil was derivatized using a new development in polyurethane technology by combination with polyethylene glycol under basic condition. Methods used in the process involved polycondensation and transesterification [6] where low reaction temperature and short reaction time as well as high percentage of yield are offered. The RBD palm kernel oil (Lee Oilmill, Klang) together with a reagent, which was a mixture of proprietary polyhydroxyl compound and basic catalyst were reacted at ratio of 80 : 20 to get the highest functionality value possible. The reaction was carried out in laboratory scale. The mixture was continuously stirred in a 2L-glass reactor and was maintained at 183± 2 ◦C for 20–30 min, with nitrogen blanket throughout the process. The reflux flask was connected to a condenser and the vacuum pump to withdraw the water from the system. The progress of the reaction was monitored by sampling at intervals. The samples were then analyzed. At the end of the reaction, the polyol produced was kept in a sealed cap glass container for analysis. 120 g of crude MDI (Cosmonate M-200, Cosmopolyurethane, Port Klang) was poured into 100 g of the mixture of the RBD palm kernel oil polyol with additives (surfactant, catalyst and water) and was mixed thoroughly using a standard propeller with speed of 3500 rpm for 10 s. The mixture was then poured into a waxed mold, covered and screwed tight. The foam was demolded after 10 min. It was then conditioned for 16 h at 23± 2 ◦C before characterization. Foams were characterized for their apparent densities, compression strength, dimensional stability and water absorption following the standard method BS 4370: Part 1: 1988 (Rigid polyurethane foam produced by the press injection method). The RBD palm kernel oil changed from a cloudy pale yellow solid (at 24–25 ◦C) before derivatization to a clear golden yellow liquid after reaction. It has a viscosity of 262.5 mpa s and density 948.2 kg/m3 at 25 ◦C. The moisture content was 0.12% and it had a pH value of about 9–10. The cloud point was observed at 13 ◦C. The hydroxyl number calculated was approximately in the range of 350–370 mg KOH/g sample. Through gel permeation chromatography (GPC), the molecular weight was calculated at the range of 430– 450, leading to functionality value of 2.8–3.0. The purity of the synthesized polyol was checked by thin layer chromatography and was confirmed to be reproducible. Fig. 1 show the two peaks used for monitoring the derivatization process. Peak B does not appear in the FTIR spectrum of underivatized RBD palm kernel oil. The ratios of the percentage transmittance of these two peaks are calculated and plotted against the reaction temperatures.

Experimental and finite element study of profiled steel sheet dry board folded plate structures

Abstract: Folded plate structures constructed with profiled steel sheeting connected to dry boards by self drilling, self tapping screws (known as the PSSDB system) are being proposed as an alternative to traditional forms of roof construction. This paper describes the analysis, testing, and the structural behaviour of such kind of structures. The proposed efficient and load bearing structural system consists of an assembly of individual PSSDB panels connected by steel angle plates at the ridges, formed to the required shape, width and span. An analytical model using finite element method has been proposed. The profiled steel sheeting was idealised as an equivalent homogeneous orthotropic thin shell plate elements of constant thickness. Two directional plate elements were proposed in modelling the connection between profiled steel sheeting and dry board to include biaxial shear deformation. The proposed analytical method has been used to analyse the results of full-scale folded plate PSSDB tests and is found to give good results.

Taking the Plasticizer out of Methacrylic‐Acrylic Membranes for K+‐Selective Electrodes

Abstract: Methacrylic-acrylic copolymers that can be externally or internally plasticized were used to fabricate potassium ion-selective electrodes (ISE) with crown ethers as the potassium selective ionophores. Copolymers which required external plasticizer have higher methacrylate content and glass transition temperatures (Tg) of approximately +30 °C whereas the internally plasticized (self-plasticized) copolymer is high in acrylate with Tg≈–27°C. Nonlipophilic crown ethers such as benzo-15-crown-5 and benzo-18-crown-6 could be included in the plasticized copolymers and yielded functional ISEs, but as with the plasticized PVC membranes these crown ethers tend to show some leaching which reduced the ISE lifetime; they were also incompatible with the ‘self-plasticized copolymer’, forming opaque membranes and electrodes of no potassium selectivity. In contrast, lipophilic crown ethers such as bis- or mono-nitrobenzo-15-crown-5 were found to be compatible with the self-plasticized copolymers yielding ISEs with good potassium ion selectivity, closely resembling plasticized PVC membrane based electrodes even though these new membranes contained no added plasticizer. This work has shown that it is possible to prepare ISEs based on nonplasticized methacrylic-acrylic polymers using lipophilized crown ethers to ensure compatibility with the polymer and deter leaching.