Optimization of the mechanical properties of polyester/coconut shell ash (CSA) composite for light-weight engineering applications.

The mechanical properties of coconut shell ash (CSA) reinforced polyester composite have been optimized. Various test specimens were developed by dispersing 10, 20, 30 and 40 wt.%, of CSA in unsaturated polyester resin in decreasing particle sizes of 40, 30, and 20 µm in an open mould using hand lay-up technique. Tensile, flexural, and impact strengths, as well as tensile and flexural moduli and Shore D hardness of all test samples were determined. The results showed that 10-20 wt.% CSA increased tensile, flexural, impact strengths and flexural modulus for all particle sizes, but 30-40 wt. % CSA engendered depreciation in corresponding performance. For all particle sizes, 10-40 wt. percent CSA resulted in an increase in tensile strength, whereas 10-40 wt. percent resulted into a linear increase in Shore D hardness. Further observation portrayed that in each case, the finest CSA (20 µm) have the optimum result. Statistical analysis carried out on experimental outcomes confirmed the experimental variables (particle proportion and sizes) to be significant. From the surface plot, the strength responses revealed more dependence on the individual variables than their interactions. Regression models developed for individual responses are termed statistically fit in representing the experimental data.

Development of Ecofriendly Snail Shell Particulate-Reinforced Recycled Waste Plastic Composites for Automobile Application.

The increase in demand for thermoplastics as a light-weight material for automobile application and other commercial purposes prompts more research into the available polymer resources. In this research, the possibility of enhancing the performance of recycled waste plastics (RWP) as polymer-based composites was examined. Particulate snail shell was obtained by grounding and sieving snail shells to obtain 53-63 µm passing which was used as reinforcement in the recycled waste plastics. The composites were developed by adding varying proportions of the snail shell particulate (SSP) to RWP using a randomly dispersed process in a hot compression moulding machine maintained at 190°C for 7 min. Selected properties of SSP-reinforced RWP composites were examined. The results showed an appreciable enhancement in the properties of composites developed compared to an unreinforced RWP matrix that serves as control. The ultimate tensile strength was enhanced by about 64%, while Young's Modulus and impact strength were enhanced by 37% and 29%, respectively. Wear and water repellant potentials were highly enhanced with the addition of 15 wt% of SSP with values of about 52% and 91%, respectively. This revealed that high content of the SSP contributes to the improvement of the strain-hardening potentials of the developed composites. The results showed that this composite material can be suitably adapted for use in the interior of automobiles as door sills or the floor panel.

Multiscale analysis and experimental validation of the effective elastic modulus of epoxy-dioctahedral phyllosilicate clay composite.

In this research, developed finite element codes were used to study the effective elastic modulus and stress-strain distribution profiles of epoxy resin filled with 6 wt. % microparticles of kaolinite. The random distribution of the particles was microstructurally regenerated with Digimat MSC software and random sequential algorithm codes in epoxy matrix. Stochastic representative volume element models of the composites were developed and analyzed under periodic boundary conditions. For validation, the predicted result by finite element analysis was compared with that of Mori-Tanaka's mean field homogenization scheme, selected micromechanical models and experiment. All the results indicated that 6 wt. % of kaolinite microparticles can improve the elastic modulus and load-bearing capacity of epoxy resin with <5 % error between predicted and actual results. The microstructure, phase identification and chemical characterization of the composite were also studied with scanning electron microscopy, x-ray diffraction spectroscopy and energy-dispersive x-ray spectroscopy, respectively. In addition, the particle size and distribution of the kaolinite in the epoxy matrix were experimentally investigated.

Environmentally sustainable processes for the synthesis of hydroxyapatite.

Hard tissue regeneration and regrowth have continued to be a challenge in the field of conventional medicine in this 21st century. Over the years, the regrowth of broken bones and diseased hard tissue has remained a major concern in medical research. Since the discovery of hydroxyapatite (HA), a bioceramic compound that possesses the ability to activate bone regrowth and bond directly with regenerated bone, it has subsequently become an indispensable biomaterial. Currently, it is being used across the medical fields due to its exceptional biocompatibility. This became plausible because the main mineral phase of mammalian bones is HA. It has found application in various medical fields like medical instruments, drug delivery, bone and tooth fillers, prosthetics, orthotics, and in-vitro implants. As the importance of HA geometrically increases, it is necessary to critically evaluate and propose the most economic process of synthesizing and manufacturing this important bioceramic material. This review, therefore, highlights the different sources of HA and the synthesis/production methods for each source with a strong emphasis on the environment. Thus, the appraisal was carried out based on the properties of the derived HA. Such properties include but are not limited to geometry, particle size, morphology, thermal stability, and stoichiometry to suggest the most economic and environmentally sustainable sources and processing routes.

Mechanical performance and water uptake behaviour of treated bamboo fibre-reinforced high-density polyethylene composites.

High density polyethylene (HDPE) composites reinforced with short bamboo fibre (BF) were fabricated by compression moulding technique. BF were extracted from bamboo culm and treated with 0.5 M NaOH. The composites were developed by melt-compounding various weight fractions (2, 4, 6, 8 and 10 wt.%) of the treated BF with HDPE with the aid of single screw laboratory extruder at a temperature of 180-220 °C. The extrudates were thereafter moulded into various test specimens with the aid of carver laboratory press at a temperature of 230 °C and applied pressure of 0.2 kPa for 10 min. Effect of the treated BF on the mechanical properties and water uptake behaviour of the composites were studied. The results revealed that there was enhancement in the mechanical properties from 2 - 4 wt.% of BF while the water absorption rate increased with increase in the fibre weight fraction. The morphology of the composites showed that there was a homogenous dispersion of BF at lower weight fraction, although fibre agglomeration was noticed at higher weight fraction. The results of this study revealed that treated bamboo fibres are suitable for reinforcing HDPE.

The comparison of intelligence quotients of atopic and nonatopic children in ibadan, Nigeria.

BACKGROUND: Atopy-related illnesses such as atopic dermatitis and asthma are chronic illnesses, and children suffering from such illnesses are subjected to frequent absenteeism from school. Studies have shown that the performance of children with asthma was comparable to their healthy counterparts despite their absenteeism at school, in contrast to findings in other chronic illnesses like epilepsy. AIM: In the present study, we investigated the association between atopy and intelligence quotient (IQ) scores in a group of Nigerian children in Ibadan, a city in southwestern Nigeria. MATERIALS AND METHODS: This is a cross-sectional study of children in an urban elementary school. Questionnaires to ascertain the presence of atopy-associated conditions such as hay fever, atopic dermatitis, asthma, allergic rhinitis, and allergic conjunctivitis were administered to the parents of 128 pupils in the 3(rd) to 6(th) grades of elementary school. Based on the responses to the questionnaire, pupils were categorized as being atopic and nonatopic. All the pupils underwent the Standard Progressive Matrices IQ test. The IQ scores were then compared among these two groups of children. RESULTS: Out of the children studied, 26.6% were found to have atopy and after adjusting for factors such as age and sex, the IQ scores in this atopic group were not found to be statistically different from the scores in the nonatopic group (r = 2.122872, P = 0.009). CONCLUSION: IQ scores were not statistically significantly different for children with and without atopy. Thus, the presence of atopy does not appear to be associated with low IQ scores and hence, may not be related to poor school performance.

Liver enzymes in Nigerians with lichen planus.

INTRODUCTION: Lichen planus has been reported in association with liver diseases. Clinical signs such as jaundice may not be reliable indicator of ongoing inflammation or the presence of an ongoing liver disease. Liver function test in spite of its variability may serve as a more reliable indicator of liver disease. The objective of this study is to assess the discriminant power of liver enzymes with lichen planus and control. METHODS: Sixty Nigerians with lichen planus (LP group) and 30 patients with other dermatoses control group A) and 30 apparently normal individual (control group B) had their liver enzymes assayed using the automated Hitachi 70 auto-analyzer. RESULT: There was no a statistically significant difference in the level of liver enzymes between the LP group and controls. CONCLUSION: Liver enzymes in Nigerian with lichenplanus are generally within normal limits and are comparable to individuals without lichen planus.

A 12-year review of cases of adult tetanus managed at the University College Hospital, Ibadan, Nigeria.

In this review, hospital case records of 202 adult tetanus managed between January 1990 and December 2001 in a tertiary institution in Southwestern Nigeria were reviewed. The mean age of the patients was 36.1+/-17.8 years with male:female ratio of 2.2:1 and an overall mortality rate of 64%. Patients with unfavourable outcomes spent 4.5+/-0.41 days compared with 16.6+/-1.2 days by those who survived. Factors associated with poor prognosis are age >60 years (P=0.029), incubation period <7 days (P=0.007), period of onset <48 h (P=0.0001), tachycardia with pulse rate >120/min (P=0.001) and spasm (P=0.002). Gender (P=0.11), post-injury vaccination (P=0.48) and types of antibiotics administered (P=0.49) were not significantly associated with increased mortality. The three most common complications were aspiration pneumonitis, sepsis and urinary bladder obstruction while complications with highest mortality (100%) were sepsis and cardiac arrest.

Clinicopathological study of neurofibromatosis type 1: an experience in Nigeria.

BACKGROUND: Neurofibromatosis type 1 (NF1) is the commonest single gene autosomal dominant disorder, and its diagnosis is usually composed of a set of clinical criteria. Histological examination of skin lesions is often neglected. This study was designed to evaluate the clinical and pathologic pattern of NF1 among Nigerians and to emphasize the place of histological examination. METHODS: A retrospective case study of 98 clinically diagnosed NF1 patients whose dermal mass lesions (neurofibromas) were excised and processed for histological diagnosis over a period of 22 years (1980-2001) at the University of Ilorin Teaching Hospital (UITH), Ilorin, Nigeria. RESULTS: There were 98 patients: 60 males and 38 females (ratio 3 : 2) aged 1-99 (mean +/- S.D. = 3.4 +/- 1.7) years. All patients had neurofibromas, which were benign in 95 patients (96.9%) and malignant in three (3.1%) patients, while 94 (96%) patients had cafe-au-lait spots. Benign neurofibromas were clinically cutaneous [50 (51%)], subcutaneous [37 (37.8%)] and plexiform [8 (8.2%)]. Site distribution of the neurofibromas included the extremities (50%), trunk (20.4%), head and neck (19.4%), and multiple sites (10.2%). Three patients presenting with neurofibosarcomas were aged 4, 23 and 27 years, respectively. Their deaths were responsible for the mortality rate of 3.1% recorded in this study. CONCLUSIONS: In our setting, NF1 is more common among males, with the highest density of neurofibromas covering the extremities.

Hepatitis B virus in Nigerians with lichen planus.

BACKGROUND: [corrected] Lichen planus had been reported as one of the cutaneous manifestations of Hepatitis B virus (HBV) in the literature. The prevalence of HBV among Nigerians with lichen planus has not been documented in the literature despite the high prevalence of HBV in the community, and the reports of a possible relationship between lichen planus and HBV from this centre and from other regions. The aim of this study was to determine the prevalence of HBsAg amongst Nigerians with lichen planus. METHOD: Sixty Nigerians with lichen planus (LP group) and 30 patients with other dermatoses not reportedly associated with HBV (control group A) and 30 apparently normal subjects (control group B) were screened for the presence of HBsAg by second generation ELISA. RESULTS: Nine (15%) of the 60 LP group, 2 (6.2%) of the 30 control group A and 2 (6.2%) of the 30 control group B were HBsAg seropositive. CONCLUSION: This study found a higher prevalence of HBsAg in patients with lichen planus when compared with patients with other cutaneous dermatoses and apparently normal individuals. Although a causal relationship between HBV has not been established from this study, this report reiterates the importance of screening patients with lichen planus for the presence of HBV and instituting therapy in those found positive.

Retrospective analysis of typhoid fever in a tropical tertiary health facility.

A retrospective analysis of cases diagnosed as typhoid fever over a ten-year period at the University College Hospital, Ibadan, Nigeria was carried out to assess the presentation pattern, laboratory investigation, mortality and mode of therapy. Incidence was of typhoid fever was highest in the dry months of the year. The mean age of survivors and the dead are 25.7 and 21.9 years respectively. Most of the patients presented with fever, abdominal pains and other gastrointestinal symptoms such as vomiting, constipation and diarrhoea. There was no specific temperature pattern but pulse rate > or = 120/minute was significantly associated with mortality. The commonest complication was intestinal perforation followed by haemorrhage with septic shock playing a prominent role in mortality. Mortality rate of 22.2% was recorded which is not significantly different from the 24% recorded at the same centre over three decades ago and most of them died within nine days of admission with 50% dying within 3 days. Most patients were scantily investigated with poor yield on blood, stool and urine cultures. Widal's test was not a favoured investigation and was not helpful in diagnosis. Chloramphenicol was the drug of choice as monotherapy, while metronidazole and gentamicin were used in cases of gut perforation. It is concluded that typhoid fever is still a major health concern in the tropics and efforts need to be geared up to combat this preventable scourge by improvement in basic necessities of life such as potable water, hygienic food in addition to health education.

Hepatitis C virus and lichen planus in Nigerians: any relationship?

BACKGROUND: The association of lichen planus with Hepatitis C virus (HCV) has been widely reported in the literature. No such association, however, has been reported amongst black Africans in whom HCV is thought to be endemic. Lichen planus is a frequently encountered dermatosis in this racial group as well. The aim of this study was to determine the prevalence of anti-HCV amongst Nigerians with lichen planus. METHODS: Fifty-seven Nigerians with lichen planus (LP group) and 24 patients with other dermatoses not reportedly associated with HCV (control group A) and 24 apparently normal subjects (control group B) were screened for the presence of anti-HCV by second generation ELISA. RESULTS: Nine (15.8%) of the 57 LP group, 6 (25%) of the 24 control group A and none out of the 24 control group B were seropositive for anti-HCV. CONCLUSION: The prevalence of anti-HCV amongst Nigerian with lichen planus is lower than amongst patients with other dermatoses not associated with HCV but higher than amongst apparently normal control. It would appear that the prevalence of HCV is high in Nigeria and not necessarily in lichen planus as a specific entity.

Lichen planus following hepatitis B vaccination in an African girl.

Lichen planus is a papulosquamous disorder with distinctive clinical features. Until now the aetiology has been largely unknown, however, several postulations have been proposed. The immunopathogenic basis has been most favoured. We report a case of a 13-year-old girl who presented with Lichen planus after receiving the second dose of hepatitis B virus (HBV) vaccination. This report, similar to earlier reports, appears to support the immunopathogenic basis of Lichen planus.

Modulation of protein kinase C activity in Plasmodium falciparum-infected erythrocytes.

Infection of human erythrocytes with the malaria parasite Plasmodium falciparum induces many morphological and biochemical changes in the host cell. Host serine/threonine protein kinases could be involved in some of these processes. The aim of this study was to determine the effect of infection on red blood cell protein kinase C (PKC) and establish the importance of this enzyme in parasite growth and sexual stage differentiation. Phorbol myristate acetate (PMA)-induced translocation of erythrocyte PKC activity is impaired in erythrocytes enriched for mature asexual stage infected cells. Western blotting shows that this is due to a relative reduction in membrane PKC protein levels rather than inhibition of enzyme activity and analysis of PKC activity isolated from whole cell lysates by DE52 chromatography suggests that total activatable PKC levels are lower in infected erythrocytes. A reduction in PMA-induced activation is also observed in PKC assays performed in situ. Downregulation of erythrocyte PKC by overnight incubation with PMA before infection causes a significant decrease in the rate of the asexual growth, suggesting that the enzyme, although lost later in infection, may be important in the earlier development of the parasite. By contrast, the lack of PKC had no effect on the production of sexual stage parasites.

Sexual-stage-specific RNA expression of a new Plasmodium falciparum gene detected by in situ hybridisation.

A gene, Pf77, transcribed in the sexual stages of Plasmodium falciparum was isolated from a genomic expression library with a polyclonal antibody raised to gametocyte proteins. The entire coding region was obtained from a series of overlapping genomic and cDNA clones (from gametocyte RNA). A single open reading frame is present with no introns and no tandem repeat sequences. A Pf77 probe hybridised to a single transcript present in RNA prepared from purified gametocytes and could not be detected in RNA prepared from asexual blood stages. In situ hybridisation studies confirmed that the expression of Pf77 mRNA is sexual-stage-specific and in addition, showed that Pf77 mRNA is present only in female gametocytes during the vertebrate stages of the parasite's development.

Sensitivity of Plasmodium falciparum in The Gambia to co-trimoxazole.

In The Gambia co-trimoxazole is used widely to treat children with an acute respiratory infection (ARI). Because malaria may sometimes be mistaken for ARI, some children with malaria are treated with co-trimoxazole. Therefore, we investigated the sensitivity of Gambian isolates of Plasmodium falciparum to this drug. Six days after the start of treatment with co-trimoxazole 3.3% of blood films of 65 asymptomatic subjects were positive, and 7.7% were positive after 21 d. One of 10 patients with ARI and malaria treated with co-trimoxazole had a positive blood film 3 d after the start of treatment but was negative thereafter. All 10 patients recovered satisfactorily. Thirty 'wild' isolates of P. falciparum were tested in vitro against co-trimoxazole at a ration of 5 parts sulphamethoxazole (SMZ) to 1 part trimethoprim (TMP). The mean EC50s, using a 36 h assay, were 1.2 x 10(-7) and 2.5 x 10(-8) M for SMZ and TMP respectively. When a [3H]hypoxanthine incorporation assay was employed, values of 5.7 x 10(-7) M for SMZ and 1.2 x 10(-7) M for TMP were obtained. These values are well below the peak plasma concentration. Our findings suggest that co-trimoxazole is effective against falciparum malaria in The Gambia. However, if it were to be used widely, the parasite would be likely to develop resistance to this and other dihydrofolate reductase inhibitor antimalarials.