Judul: The Effect of Woven Patterns on Flexural Behaviour of Textile Reinforced Concrete (TRC) with Ramie Fiber Reinforcement
Abstrak: Kebutuhan terhadap beton telah meningkat di Indonesia. Salah satu inovasi beton yang sedang dikembangkan adalah Textile Reinforced Concrete (TRC). Serat rami memiliki potensi untuk digunakan sebagai perkuatan TRC karena memiliki kekuatan tarik yang cukup tinggi. Penelitian bertujuan menganalisis perilaku lentur TRC dengan perkuatan serat rami. Penelitian dilaksanakan pada bulan Februari hingga Juni 2021 di IPB. Penelitian dilakukan melalui beberapa tahapan, yaitu pengujian material, mix design, penganyaman dan pelapisan serat rami, pembuatan dan perawatan benda uji, dan pengujian. Perilaku lentur TRC yang dianalisis, di antaranya kuat lentur, kekakuan, daktilitas, dan perilaku retak. Perkuatan serat rami dapat meningkatkan daktilitas dan menurunkan kekakuan pelat mortar. Akan tetapi, anyaman serat rami dengan pola anyaman tertentu dapat menurunkan kuat lentur. Pelapisan Unsaturated Polyester Resin (UPR) memberikan peningkatan kuat lentur dan daktilitas serta penurunan kekakuan pada TRC. Perilaku retak TRC serat rami terlapisi UPR mengalami beberapa fase, yaitu uncracked concrete, crack formation, crack stabilization, dan failure. Pola anyaman yang menghasilkan kuat lentur tertinggi adalah pola anyaman dua sumbu yang terlapisi UPR, sebesar 7.84 MPa., The demand of concrete has increased in Indonesia. A reinforced concrete innovation being developed is Textile Reinforced Concrete (TRC). Ramie fiber has great potential to be used as a construction material because it has advantages over other natural fibers, such as tensile strength properties. The research aims to analyzed flexural behaviour of Ramie fiber TRC. This research was conducted from February until June 2021 at IPB University. The research was carried out through several stages, that are testing of TRC materials, mix design, weaving and coating ramie fiber, manufacturing and curing test objects, and testing. The flexural behavior analyzed flexural strength, stiffness, ductility, and crack behavior. Ramie fiber reinforcement can improve ductility and reduce stiffness of mortar plates. However, woven ramie fiber with a certain woven pattern can reduce flexural strength. Coating ramie fiber with Unsaturated Polyester Resin (UPR) provides an increase in flexural strength and ductility but decrease in stiffness. Phases of crack behaviour of UPR-coated are uncracked, crack formation, crack stabilization, and failure. The woven pattern that produces the highest flexural strength is the two-axis woven pattern for UPR-coated ramie, which is 7.84 MPa.
Keyword: concrete, flexural behaviour, ramie fiber, textile reinforced concrete

Judul: Formulation and Characterization of Non-Isocyanate Tanin Based  Bio-Polyurethane as Impregnating Agent for Fibers, Threads, and Ramie Fabrics
Abstrak: Industri tekstil membutuhkan alternatif pengganti serat kapas karena nilai impornya yang tinggi. Rami (Boehmeria nivea (L.) Gaudich) berpotensi untuk dikembangkan, tetapi memiliki kelemahan seperti mudah terbakar. Resin poliuretan non-isosianat berbasis tanin (T-NIPU) dapat dijadikan sebagai impregnan rami untuk meningkatkan stabilitas termal dan sifat mekanisnya. Penelitian ini bertujuan menganalisis sintesis resin T-NIPU dan menentukan karakteristiknya, serta menganalisis serat, benang, dan kain rami terimpregnasi. Resin T-NIPU dibuat dengan mencampurkan ekstrak kental tanin, dimetil karbonat, dan heksametilentetramin. Kemudian proses impregnasi rami dengan resin T-NIPU. Rendemen ekstraksi tanin yang diperoleh yaitu 22,71%. Analisis FTIR menujukkan adanya ikatan uretan pada T-NIPU maupun pada rami terimpregnasi. Interaksi jenis formula (F1, F2, F3, dan F4) dan jenis sampel (serat, benang, dan kain rami) memengaruhi nilai kuat tarik, MOE, dan flammability. Serat rami yang diimpregnasi resin T-NIPU F3 memiliki kekuatan tarik dan MOE tertinggi. Kain rami yang diimpregnasi resin T-NIPU F3 memiliki kecepatan bakar terendah. Serat rami lebih mudah terhidrolisis dibandingkan dengan benang dan kain rami., The textile industry needs a cotton fiber substitute because of its high import value. Although ramie (Boehmeria nivea (L.) Gaudich) shows potential for development, it suffers from a significant weakness such as flammability. Tanninbased non-isocyanate polyurethane resin (T-NIPU) can be used as a ramie impregnanting agnent to enhance thermal stability and mechanical properties. This study aims to analyze the synthesis of T-NIPU resins, determine their characteristics, and examine the fibers, threads, and ramie fabric that have been impregnated with T-NIPU resins. The thick extracts of tannins, dimethyl carbonate, and hexamethylentetramine were reacted to make the T-NIPU resin. Next, the TNIPU underwent the ramie impregnation process. The resulting tannin extraction yield is 22.71%. The FTIR analysis indicates that urethane bonds are present on both T-NIPU and impregnated samples. The interaction of formula types (F1, F2, F3, and F4) and sample types (fiber, thread, and fabric ramie) affects the strength values of tensile strength, modulus of elasticity, and flammability. T-NIPU F3 resin-impregnated ramie fibers have the highest traction strength and MOE. TNIPU F3 resin-impregnated ramie fabrics have the lowest burning speed. Ramie fiber is easier to hydrolyze than ramie thread and fabric.
Keyword: bio-poliuretan, impregnasi, non-isosianat, rami, tanin

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model