Bandarlampung, Indonesia
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Agung E.H.,University Putra Malaysia | Agung E.H.,Malahayati University | Sapuan S.M.,University Putra Malaysia | Hamdan M.M.,National Defence University of Malaysia | And 2 more authors.
International Journal of Physical Sciences | Year: 2011

In this research, thermogravimetric analysis (TGA) was used to measure the amount and rate of change in the weight (weight loss) of abaca fibre reinforced high impact polystyrene (HIPS) composites as a function of temperature. The function determined the composition of abaca fibre reinforced HIPS composites on predicting the thermal stability. The optimum composites designed with composition of abaca fibre 40 wt%; maleic anhydride 1 and 3 wt%, impact modifier 4 and 6 wt% respectively. This paper studied the thermal characteristic of abaca fibre, reinforced HIPS composites as compared to the neat HIPS. The measurements were carried out in temperatures ranging from 25°C to 600°C at heating rate 20°C min-1 and nitrogen gas flow of 50 ml min-1. The results from TGA analysis have shown that the combination among the coupling agent maleic anhydride, impact modifier and abaca fibre has improved the thermal stability of composites. © 2011 Academic Journals.


Agung E.H.,University Putra Malaysia | Sapuan S.M.,University Putra Malaysia | Hamdan M.M.,National Defence University of Malaysia | Zaman H.M.D.K.,Malaysian Nuclear Agency | Mustofa U.,Malahayati University
Polymers and Polymer Composites | Year: 2011

Mechanical properties of polymer composites are influenced by many factors such as the types of fibres, the types of polymer matrix, the additives used and the adhesion between fibres and polymer matrix. To improve the interfacial adhesion between HIPS matrix and abaca fibres, a study of the optimum use of a coupling agent (MAH) and impact modifier is presented in this paper. Abaca fibre reinforced high impact polystyrene (HIPS) composites were produced with different fibre loadings (30, 40 and 50 wt.%), different compositions of coupling agent, maleic anhydride (MAH) (1, 2 and 3 wt.%) and different compositions of impact-modifier (4, 5 and 6 wt.%). A response surface methodology using Box-Behnken design was used in the design of experiments and analysis of results. Statistical analysis of mechanical properties gave very satisfactory model accuracy, because the coefficient of determinance was 0.9817 for impact strength, 0.9789 for tensile strength, 0.9672 for tensile modulus, 0.9700 for flexural strength, and 0.9747 for flexural modulus. In this study, a loading of abaca fibre of 36.76 wt.%, maleic anhydride 3 wt.%, and impact modifier 4 wt.% led to optimum individual impact strength. On the other hand, optimum individual tensile strength and tensile modulus were achieved when the loading of abaca fibre was close to 40.76 wt.%, maleic anhydride 3 wt.% and impact modifier 6 wt.%, but the optimum individual flexural strength and flexural modulus were found when the loading abaca fibre was close to 40.03 wt.%, maleic anhydride 3 wt.% and impact modifier 4 wt.%.


Agung E.H.,3400 UPM Serdang | Sapuan S.M.,3400 UPM Serdang | Hamdan M.M.,National Defence University of Malaysia | Zaman H.M.D.K.,Malaysian Nuclear Agency | Mustofa U.,Malahayati University
Key Engineering Materials | Year: 2011

In this paper, the hardness property of abaca (Musa textile Nee) fibre reinforced high impact polystyrene (HIPS) composites with maelic anhydride (MAH) used as coupling agent and styrene butadiene styrene (SBS) copolymer rubber (Cyclo resin) used as impact modifier was investigated using response surface methodology.. The composites were initially fabricated using a rolling machine and finally using a hot press machine to obtain a desired thickness. These samples were then tested for Brinell hardness test. A statistical approach of response surface methodology was used to obtain the interaction between various compositions mentioned above for abaca fibre reinforced HIPS composites. The BHN (Brinell hardness number) was analyzed using response surface methodology (Box Behnken method). © (2011) Trans Tech Publications.


Siregar J.P.,University Putra Malaysia | Siregar J.P.,Malahayati University | Sapuan S.M.,University Putra Malaysia | Rahman M.Z.A.,University Putra Malaysia | Zaman H.M.D.K.,Malaysian Nuclear Agency
Pertanika Journal of Science and Technology | Year: 2012

A study on the effects of alkali treatment and compatibilising agent on the tensile properties of pineapple leaf fibre (PALF) reinforced high impact polystyrene (HIPS) composite is presented in this paper. The tensile properties of natural fibre reinforced polymer composites are mainly influenced by the interfacial adhesion between the matrix and the fibres. In this study, several chemical modifications were employed to improve the interfacial matrix-fibre bonding and this resulted in the enhancement of tensile properties of the composites. In this study, the surface modification of pineapple fibre with alkali treatments and compatibilizer were used to improve the adhesion between hydrophilic pineapple fibre and hydrophobic polymer matrix. There are two concentrations of NaOH treatments and compatibilizer used in this study, namely, 2 and 4 wt. %. The results show that the alkali treated fibre and the addition of compatibilising agent in PALF/HIPS composites have improved the tensile strength and tensile modulus of the composites. © 2012 Universiti Putra Malaysia Press.


Hadi A.E.,University Putra Malaysia | Hadi A.E.,Malahayati University | Salit M.S.,University Putra Malaysia | Ahmad M.M.H.M.,National Defence University of Malaysia | And 2 more authors.
Pertanika Journal of Science and Technology | Year: 2011

The physical properties by natural fibre have a great importance, specifically in the structural of natural fibre which reinforces matrix. Response surface methodology with Box-Behnken (BB) design of experiment was utilized to study water absorption and melt flow index (MFI) of abaca fibre reinforced high impact polystyrene (HIPS) composites. The design utilizes fraction of weight abaca fibre, maleic anhydride (MAH), and impact modifier to develop models for characteristic behaviours of water absorption and MFI of composites. Abaca fibre reinforced high impact polystyrene (HIPS) composites were produced with different fibre loadings (30, 40, and 50 wt%), different compositions of coupling agent, maleic anhydried (MAH) (1, 2, and 3 wt%) and different compositions of impact modifier (4, 5, 6 wt%). The individual optimum of water absorption was found when loading abaca fibre close to 34.61 wt%, maleic anhydride 1 wt%, and impact modifier 4.01 wt%. The individual optimum of melt flow index dealt with loading abaca fibre 36.71 wt%, maleic anhydride 3 wt% and impact modifier 4.02 wt%. Meanwhile, the optimum condition for water absorption of abaca fibre reinforced HIPS composites was followed by a decreasing trend of the value of melt flow index. © Universiti Putra Malaysia Press.


Wahono C.S.,Brawijaya University | Rusmini H.,Brawijaya University | Rusmini H.,Malahayati University | Soelistyoningsih D.,Brawijaya University | And 6 more authors.
International Journal of Clinical and Experimental Medicine | Year: 2014

Vitamin D deficiency has been associated with pathogenesis of autoimmune diseases including SLE; however, there were still lack of data about the effects of administration of vitamin D in immune regulation in SLE patients. The aim of this study was to investigate the effects of calcitriol/1,25(OH)2D3 on dendritic cells maturation and Th17 and Treg cells activation in SLE patients with hypovitamin D. The monocytes and lymphocytes of five SLE patients with hypovitamin D were divided into 4 groups, P0 (0 nM/control), P1 (1 nM), P2 (10 nM), and P3 (100 nM) as cultured samples. Flowcytometry analysis was used to evaluate dendritic cell maturation (the percentage of CD40, CD86, and HLA-DR expression) and the amount of Th17 and Treg cells (the percentage of Th17 and Treg cells). Cytokines production of IL-12, IL-17A, and TGF-β measured by ELISA. This study showed significant differences in CD40, CD86, HLA-DR expressions, and Th17 percentage in 10 nM of 1,25(OH)2D3 compared to that of control. For cytokines secretion, there was also significant difference between IL-12p70 and IL-17A levels in 10 nM of 1,25(OH)2D3 compared to that of control. The 1,25(OH)2D3 increased Treg cells and TGF-β level but not significant. Our study concluded that 1,25(OH)2D3 inhibited dendritic cells maturation and Th17 cells activation in SLE patients. The 1,25(OH)2D3 increased Treg cells but not significant.


Raras T.Y.M.,Brawijaya University | Rusmini H.,Malahayati University | Wisudanti D.D.,Brawijaya University | Chozin L.N.,Saiful Anwar Hospital
Pakistan Journal of Nutrition | Year: 2015

Regular consumption of kefir promotes beneficial physiological and therapeutic effects including stimulation of immune response. In this study, we investigated the immunomodulatory effects of kefir on peripheral mononuclear cells (PBMCs) derived from patients diagnosed with pulmonary tuberculosis (TB). PBMCs were isolated, treated with different concentration of kefir (1/20, 1/50, 1/100 and 1/200) and cultured for 4 days. The proportion of CD4+ and CD8+cells was analyzed by flow cytometry and the production of Th1 cytokines IL-2 and IFN-g and Th2 cytokines IL-4 and IL-10 was determined by ELISA. The results indicate that kefir slightly stimulated CD4+ as well as CD8+, but the effect was insignificant. Low doses of kefir significantly induced the secretion of IL-10 but not IL-2, IL-4, or IFN-γ. We conclude that kefir in a low concentration stimulates Th2 rather than Th1-type immune response and therefore works as an immunosuppressant for early diagnosed TB patients. © Asian Network for Scientific Information, 2015.


Febrina R.,Yamaguchi University | Febrina R.,Malahayati University | Sekine M.,Yamaguchi University | Noguchi H.,Yamaguchi University | And 4 more authors.
Ecological Modelling | Year: 2015

Water sounds are believed to be important in triggering the upriver ascent behavior of migratory fish species. Modeling the effect of underwater sound on fish preference represents a promising technique to determine migratory paths for the comprehensive analysis of river habitat suitability. In this study, we aimed to determine the preference and weight of underwater sounds by laboratory experiments using adult and juvenile ayu (Plecoglossus altivelis). A watercourse with an underwater speaker installed at one end was used for the experiments. Sound was emitted from the speaker at different sound pressure levels. The sound sources included pure tones (100. Hz, 200. Hz, 400. Hz, and 800. Hz), white noise, recorded sound from a weir on the Fushino River, and recorded sound at a fish ladder on the Misumi River (Japan). The results showed that juvenile and adult ayu avoided the pure sound of 100. Hz and recorded sound of the Fushino River weir. In contrast, both adults and juveniles preferred the pure sound of 200. Hz and recorded sound of the fish ladder. Moreover, by comparing the obtained quantitative preference parameters for sounds, we found that adult ayu expressed higher preference for sound than juveniles. We designed a procedure to calculate sound preference and built it into our fish behavior simulation model on geographic information system (GIS) software. We believe that the model could successfully reproduce observed fish migration behavior in rivers. This technique could be used for designing an underwater soundscape to attract fish to the entrances of fish ladders or to keep fish away from hydropower plants. © 2014 Elsevier B.V.


Malahayati University | Entity website

Bersama SLiMS, temukan koleksi yang anda butuhkan. Mudah dan Cepat Kami mempunyai beberapa koleksi seperti skripsi, laporan praktik, tugas akhir, buku dari klas 000-900 sebagai referensi mahasiswa maupun umum ...


Malahayati University | Entity website

Wisata pantai di Provinsi Lampung memang menjadi primadona bagi para wisatawan untuk dikunjungi. Salah satunya Pantai Laguna Helau, pantai ini berada diDesa Ketapang, Kecamatan Kalianda, Lampung Selatan ...

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