| 1. |
- Ramamoorthy, S. K., et al.
(författare)
-
Effect of water absorption on mechanical properties of soybean oil thermosets reinforced with natural fibers
- 2012
-
Ingår i: Journal of reinforced plastics and composites (Print). - : Sage Publications Ltd.. - 0731-6844 .- 1530-7964. ; 31:18, s. 1191-1200
-
Tidskriftsartikel (refereegranskat)abstract
- Natural fiber composites are known to absorb more water than glass fiber reinforced composites. In this study, hybrid natural fiber composites were prepared by combining different fiber reinforcements, and both the water absorption and the mechanical properties were studied. Compression molding technique was used to manufacture composite laminates from a bio-based resin (acrylated epoxidized soybean oil) and natural fibers: non-woven and woven jute, non-woven regenerated cellulose mat (Lyocell and viscose), and woven glass fiber. The composite laminates were cured at 160–170 C and 40 bar, with a fiber content of 40 wt%. We investigated effect of pretreatment of regenerated cellulose fiber using 4% NaOH solution. The gravimetric water absorption was tested by exposure to water for 10 days. Specimens were cut from composites with laser-cutting technique according to ISO standards, and tested for tensile, flexural, and impact strength. To determine the influence of water absorption on the mechanical properties, specimens were immersed in distilled water for 10 days before testing. As a reference, dry specimens were tested. The results showed that water absorption was reduced by producing hybrid composites with jute fibers, glass fiber, and Lyocell fiber. The tensile, flexural, and impact properties were improved by inclusion of glass fiber and Lyocell in the composite. The tensile and flexural properties of natural fiber reinforced composites were mostly affected by the influence of water, but this was improved considerably by hybridization with glass and Lyocell fibers. The viscoelastic properties of the manufactured composites and hybrid composites were studied using dynamic mechanical thermal analysis.
|
|
| 2. |
- Adekunle, K. F., et al.
(författare)
-
Impact and flexural properties of flax fabrics and lyocell fiber reinforced bio-based thermoset for automotive and structural applications
- 2012
-
Ingår i: ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials. - : European Conference on Composite Materials, ECCM. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- A bio-based thermoset resin was reinforced with flax fabrics and Lyocell fiber. The effect of different weave architecture was studied with four flax fabrics with different architecture: plain, twill (two different types) and dobby. The effect of the outer ply thickness was studied and characterized with flexural and impact testing. Composites manufactured with plain weave reinforcement had the best mechanical properties. The tensile strength, tensile modulus, flexural strength, flexural modulus and impact strength was 280 MPa, 32 GPa, 250 MPa, 25 GPa and 75 kJ/m2 respectively.
|
|
| 3. |
|
|
| 4. |
- Adekunle, K., et al.
(författare)
-
Jute fiber reinforced methacrylated soy bean oil based thermoset composites prepared by vacuum injection molding technique
- 2012
-
Ingår i: Journal of Biobased Materials and Bioenergy. - : American Scientific Publishers. - 1556-6560 .- 1556-6579. ; 6:2, s. 172-177
-
Tidskriftsartikel (refereegranskat)abstract
- Bio-based composites based on soybean oil thermoset resin were manufactured with vacuum injection molding technique. Methacrylated soybean oil (MMSO) was processed with vacuum injection molding technique without blending with styrene. The composites produced had comparatively good mechanical properties like jute composite reinforced acrylated epoxidised soybean oil (AESO) resin blended with styrene. Although the tensile strength of the jute reinforced AESO composites are slightly higher than the jute reinforced MMSO composites which was attributed to blending of AESO with styrene. However, the difference in Youngs' modulus was negligible because they have approximately equal stiffness between 2.6 GPa and 2.8 GPa. The jute reinforced AESO composites showed relatively higher flexural strengths and moduli than the MMSO counterparts. This difference was also attributed to the blending of AESO with reactive diluent such as styrene. In order to determine the dimensional stability of the composite manufactured, water absorption test was carried out and the conclusion was that the moisture uptake of the jute reinforced composites was the same, this was expected.
|
|
| 5. |
- Jiang, W., et al.
(författare)
-
COVID-19 is associated with bystander polyclonal autoreactive B cell activation as reflected by a broad autoantibody production, but none is linked to disease severity
- 2023
-
Ingår i: Journal of Medical Virology. - : Wiley. - 0146-6615 .- 1096-9071. ; 95:1
-
Tidskriftsartikel (refereegranskat)abstract
- Coronavirus disease 2019 (COVID-19) is associated with autoimmune features and autoantibody production in a small subset of the population. Pre-existing neutralizing antitype I interferons (IFNs) autoantibodies are related to the severity of COVID-19. Plasma levels of IgG and IgM against 12 viral antigens and 103 self-antigens were evaluated using an antibody protein array in patients with severe/critical or mild/moderate COVID-19 disease and uninfected controls. Patients exhibited increased IgGs against Severe acute respiratory syndrome coronavirus-2 proteins compared to controls, but no difference was observed in the two patient groups. 78% autoreactive IgGs and 93% autoreactive IgMs were increased in patients versus controls. There was no difference in the plasma levels of anti-type I IFN autoantibodies or neutralizing anti-type I IFN activity of plasma samples from the two patient groups. Increased anti-type I IFN IgGs were correlated with higher lymphocyte accounts, suggesting a role of nonpathogenic autoantibodies. Notably, among the 115 antibodies tested, only plasma levels of IgGs against human coronavirus (HCOV)-229E and HCOV-NL63 spike proteins were associated with mild disease outcome. COVID-19 was associated with a bystander polyclonal autoreactive B cell activation, but none of the autoantibody levels were linked to disease severity. Long-term humoral immunity against HCOV-22E and HCOV-NL63 spike protein was associated with mild disease outcome. Understanding the mechanism of life-threatening COVID-19 is critical to reducing mortality and morbidity.
|
|
| 6. |
- Olaniyan, Subulade A., et al.
(författare)
-
Tumour necrosis factor alpha promoter polymorphism, TNF-238 is associated with severe clinical outcome of falciparum malaria in Ibadan southwest Nigeria
- 2016
-
Ingår i: Acta Tropica. - : Elsevier BV. - 0001-706X .- 1873-6254. ; 161, s. 62-67
-
Tidskriftsartikel (refereegranskat)abstract
- Tumour necrosis factor (TNF) - alpha has been shown to play an important role in the pathogenesis of falciparum malaria. Two TNF promoter polymorphisms, TNF-308 and TNF-238 have been associated with differential activity and production of TNF. In order to investigate the association between TNF-308 and TNF-238 and the clinical outcome of malaria in a Nigerian population, the two TNF polymorphisms were analysed using Sequenom iPLEX Platform. A total of 782 children; 283 children with uncomplicated malaria, 255 children with severe malaria and 244 children with asymptomatic infection (controls) were studied. The distribution of TNF-308 and TNF-238 genotypes were consistent with the Hardy-Weinberg equilibrium. Distribution of both TNF polymorphisms differed significantly across all clinical groups (TNF-308: p = 0.007; TNF-238: p=0.001). Further tests for association with severe malaria using genotype models controlling for age, parasitaemia and HbAS showed a significant association of the TNF-238 polymorphism with susceptibility to severe malaria (95% CI = 1.43-6.02, OR= 2.94, p = 0.003237) The GG genotype of TNF-238 significantly increased the risk of developing cerebral malaria from asymptomatic malaria and uncomplicated malaria (95% CI = 1.99-18.17, OR= 6.02, p <0.001 and 95% CI= 1.78-8.23, OR= 3.84, p <0.001 respectively). No significant association was found between TNF-308 and malaria outcome. These results show thegenetic association of TNF-238 in the clinical outcome of malaria in Ibadan, southwest Nigeria. These findings add support to the role of TNF in the outcome of malaria infection. Further large scale studies across multiple malaria endemic populations will be required to determine the specific roles of TNF-308 and TNF-238 in the outcome of falciparum malaria infection.
|
|
| 7. |
- Omokungbe, Opeyemi R., et al.
(författare)
-
Analysis of the variability of airborne particulate matter with prevailing meteorological conditions across a semi -urban environment using a network of low-cost air quality sensors
- 2020
-
Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 6:6
-
Tidskriftsartikel (refereegranskat)abstract
- The concentrations of fine and coarse fractions of airborne particulate matter (PM) and meteorological variables (wind speed, wind direction, temperature and relative humidity) were measured at six selected locations in Ile Ife, a prominent university town in Nigeria using a network of low-cost air quality (AQ) sensor units. The objective of the deployment was to collate baseline air quality data and assess the impact of prevailing meteorological con- ditions on PM concentrations in selected residential communities downwind of an iron smelting facility. The raw data obtained from OPC-N2 of the AQ sensor units was corrected using the RH correction factor developed based k -Kohler theory. This PM (corrected) fast time resolution data (20 s) from the AQ sensor units were used to create daily averages. The overall mean mass concentrations for PM2.5 and PM10 were 213.3, 44.1, 23.8, 27.7, 20.2 and 41.5 mu g/m(3) and; 439.9, 107.1, 55.0, 72.4, 45.5 and 112.0 mu g/m(3) for Fasina (Iron -Steel Smelting Factory, ISSF), Modomo, Eleweran, Fire Service, O.A.U. staff quarters and Obafemi Awolowo University Teaching and Research Farm (OAUTRF), respectively. PM concentration and wind speed showed a negative exponential distribution curve with the lowest exponential fi t coef ficient of determination (R-2) values of 0.08 for PM2.5 and 0.03 for PM10 during nighttime periods at Eleweran and Fire service sites, respectively. The relationship between PM concen- tration and temperature gave a decay curve indicating that higher PM concentrations were observed at lower temperatures. The exponential distribution curve for the relationship between PM concentration and relative humidity (RH) showed that PM concentrations do not vary for RH 80 % while stronger relationship was noticed with higher PM concentration for RH 80 % for both day and nighttime. The performances of the MLR model were slightly poor and as such not too reliable for predicting the concentration but useful for improving predictive model accuracy when other variables contributing to the variability of PM is considered. The study concluded that the anthropogenic and industrial activities at the smelting factory contribute signi ficantly to the elevated PM mass concentration measured at the study locations.
|
|
