Yusuf Bramastya Apriliyanto
Department of Chemistry, Bogor Agricultural University, Chemistry Building, Wing 1, 3rd Floor, Tanjung St., IPB Darmaga Campus, Bogor 16680, Indonesia

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Enhancing Thermal and Mechanical Properties of UHMWPE/HA Composite as Tibial Tray Yusuf Bramastya Apriliyanto; Sri Sugiarti; Sulistioso Giat Sukaryo
Indonesian Journal of Chemistry Vol 20, No 3 (2020)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (551.859 KB) | DOI: 10.22146/ijc.44086

Abstract

A bearing material in an artificial knee joint has to have good thermal and mechanical properties to prevent wear in order to be used as a tibial tray. Despite its well-known good properties, ultrahigh molecular weight polyethylene (UHMWPE) still needs to be modified to enhance its physical strength in its use in artificial joints. In this research, composites made from UHMWPE and hydroxyapatite (HA) were prepared by mechanical alloying and hot press method and their thermal and mechanical properties were modified using gamma rays. The composites were prepared using various HA loading ratios and irradiated using gamma rays at doses of 0, 25, 50, and 75 kGy. The effects of HA loading and gamma irradiation on thermal and mechanical properties were studied by various methods. The results showed that the addition of HA enhanced the hardness of UHMWPE by 8–15% and the maximum stress up to 38%. Gamma irradiation enhanced the crystallinity by 113–172%, the melting point by 0.6–0.7%, and decreased the break elongation of composites by 23–48%. Addition of polyvinyl alcohol (5% w/w) in composites reduced their rigidity by 16–47% and hardness by 3–9%.
Novel Absorber Material Design Based on Thiazole Derivatives Using DFT/TD-DFT Calculation Methods for High-Performance Dye Sensitized Solar Cell Nurrosyid, Naufan; Fahri, Mirad; Apriliyanto, Yusuf Bramastya; Basuki, Rahmat
Indonesian Journal of Chemical Studies Vol. 1 No. 1 (2022): Indones. J. Chem. Stud., June 2022
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (362.122 KB) | DOI: 10.55749/ijcs.v1i1.5

Abstract

Thiazole derivative molecules with a low energy gap have been successfully designed using the DFT/TD-DFT calculation methods. The calculations were simulated by adding varied numbers of thiophenes (1, 2, 3, and 10) and electron donating molecules of –H, -NH2, -OCH3, and –COOH in the ethanol solvent. The best thiazole derivative was the molecule constructed using a long-conjugated bridge of 10-thiophenes, the carboxyl anchoring site, and an amine addition as the electron donating molecule with an energy gap of 1.66 eV and a strong UV-Vis absorption in the red light region (673.20 nm). These designed molecules are beneficial to be applied in the equator area such as Indonesia. Further, the profound effects of the thiophene bridge in terms of the structural and energy gaps, and the variation of electron-donating molecules affected the photonic properties have been demonstrated in this paper.
Comparative Analysis of Electronic Structures Calculations: A Simple Test Case Set for Kohn-Sham Density Functional Theory and Hartree-Fock Methods Apriliyanto, Yusuf Bramastya; Nurrosyid, Naufan
Indonesian Journal of Chemical Studies Vol. 2 No. 2 (2023): Indones. J. Chem. Stud., December 2023
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ijcs.v2i2.33

Abstract

A comparative analysis on the performance of Kohn-Sham density functional theory (KS-DFT) and Hartree-Fock (HF) methods to obtain reliable energy and electronic properties has been performed in this study using a simple test case. It is crucial to re-emphasize the key differences between these methods to address common conceptual difficulties that occur among freshmen studying basic computational chemistry. The results suggested that the eigenvalue theorem in determining ionization potential could be well implemented in the HF but not in the KS-DFT method. The total energy difference between ionized and non-ionized species was an appropriate procedure to calculate the first ionization potential within the KS-DFT method. The HOMO-LUMO gap in the HF was larger than the gaps obtained from the KS-DFT method. Among all of the performed calculation methods, the B3LYP hybrid functional provided better total energy where the eigenvalues were located between the HF and the LDA/GGA functionals.
Reaction Mechanism in Standardized α-Cellulose Content Test: Study from Boehmeria nivea Fiber Rahmawati, Fani; Basuki, Rahmat; Fahri, Mirad; Apriliyanto, Yusuf Bramastya; Kurniadi, Tedi; Nareswari, Vania Agatha; Sandri, Azzahra; Istiqomah, Tiara
Indonesian Journal of Chemical Studies Vol. 3 No. 1 (2024): Indones. J. Chem. Stud., June 2024
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ijcs.v3i1.45

Abstract

In defense industry, α-cellulose is the main component of nitrocellulose propellant. However, a detailed description of the reaction mechanism of each treatment step in SNI 0444-2009 is still very scarce. This study addresses this gap by presenting the reaction mechanisms of each treatment and the symbols used in the SNI 0444-2009 procedure. The separation of lignin from α-cellulose occurred by breaking the C‒O bond linking them. This bond was broken by the ‒OH group of NaOH via a hydrolysis reaction. The reaction was initiated with the elimination of a hydrogen atom from the lignin structure by the hydroxyl ion (‒OH), and the C‒O bond was broken by a hydrolysis reaction. The breaking of this bond was indicated by the disappearance of the IR peaks at wavenumbers 1049 and 1190 cm–1 in the filtrate after extraction. The SNI 0444-2009 method for the α-cellulose content test was carried out by a redox back titration of Cr(VI) with Fe(II) from ferrous ammonium sulfate. This titration was conducted to calculate the amount of Cr(VI) ions in potassium dichromate or Cr(VI) that did not react with lignin or beta cellulose in the filtrate. Understanding the contribution and reaction mechanisms of each compound involved in the SNI 0444-2009 procedure contributed to obtaining accurate data on α-cellulose content. In this study, the calculated α-cellulose content of the flax fiber was 96.75%. Furthermore, the detailed mechanism of the redox reaction was discussed in detail in this paper.
Enriching of society’s understanding of command-oriented leadership through an interactive virtual discussion Fahri, Mirad; Stiawan, Elva; Ariyanti, Dita; Basuki, Rahmat; Apriliyanto, Yusuf Bramastya; Hasibuan, Anggi Khairina Hanum; Kurniadi, Tedi; Putra, M. Sulthon Nurharmansyah; Septaningsih, Dewi; Tiarani, Sekar Ilma; Mayori, Ersha; Wiana, Regita Andriani; Yunita, Amalia; Nurrosyid, Naufan; Prasojo, Agus Eko; Putri, Riyanti
Journal of Community Service and Empowerment Vol. 5 No. 2 (2024): August
Publisher : Universitas Muhammadiyah Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22219/jcse.v5i2.27961

Abstract

In the post-pandemic era, many interactive activities have been flexibly generated through virtual conditions. Accordingly, some problems could appear in terms of leadership, such as difficulties in maintaining the audience’s attention during the event. Thus, the utilization of a command-based leadership style that could straightforwardly maintain audience focus ought to be considered to be adopted. However, both the command-based leadership style and its prospective aspects have not been widely understood by society. This community service aims to deliver a proper understanding of the command-based leadership style through interactive virtual discussion between experts in teaching activities of defense-based science and society consisting of Indonesian teachers, high school students as well as academics. Statistical results of pre-test and post-test scores showed enhancement of the participants’ understanding of command-based leadership. Hopefully, some relevant aspects of their new perspective of command-based leadership can be properly adopted and effectively implemented to answer current challenges, such as in terms of managing people in virtual conditions. 
Immobilization of Cerium(IV) Oxide onto Reduced Graphene Oxide in Epoxy Resin Matrix as Radar Absorbing Composite for X-band Region Bolilanga, Patricya Inggrid Wilhelmina; Basuki, Rahmat; Apriliyanto, Yusuf Bramastya; Prasojo, Agus Eko; Lazuardy, Ardyan; Anitasari, Reza; Putri, Riyanti; Sasongko, Nugroho Adi; Santiko, Arief Budi
Indonesian Journal of Chemistry Vol 24, No 6 (2024)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.94404

Abstract

The rGO/CeO2/epoxy composite has been successfully prepared as radar absorbing material (RAM) for the X-band (8–12 GHz) region. The reduced graphene oxide (rGO) originated from pencil graphite oxide (GiO) was synthesized through the modified Hummer method. The synthesis of rGO/CeO2/epoxy was conducted by immobilization of cerium(IV) oxide into rGO (rGO/CeO2) via hydrothermal method and followed by composited the rGO/CeO2 with epoxy resin matrix. Morphological analysis by SEM-EDX indicates that the rGO/CeO2 structure appears to be a tangled layer of edges randomly aggregated, and CeO2 is uniformly anchored on the rGO surface. From the diffractogram result of the XRD instrument, rGO exhibits changes in crystallinity, indicating a transformation of the interlayer structure from multilayer GiO to a single layer of rGO. The presence of Ce–O was indicated at wavenumber 553 cm−1 of rGO/CeO2 by FTIR. The microwave absorbing performance of rGO/CeO2/epoxy conducted by vector network analyzer (VNA) showed that the RL value of the composite was −3.22 dB (47% of electromagnetic wave absorption) at a frequency of 9.25 GHz at the thickness of 1 mm composite. The composite has the promising prospect of being developed as a captivating candidate for the new type of microwave absorptive materials.
Fluorine Substitution in Diamine Covalent Organic Frameworks: Computational Analysis of CO2/N2 Adsorption and Permeability Darmawan, Noviyan; Apriliyanto, Yusuf Bramastya; Jati, Andreas Ary Chrisna; Kusumawardani, Cahyorini
Science and Technology Indonesia Vol. 10 No. 1 (2025): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.1.18-26

Abstract

In this study, we investigated the effect of fluorine substitution on a previously reported diamine based covalent organic framework (COF), designated as IPB-2H. A new fluorinated analogue namely IPB-2F2 was modeled and its adsorption and permeability characteristics for CO2/N2 gas mixtures were evaluated through computational analysis. Ab initio structural optimization results showed that the reduced pore size of IPB-2F2 compared to IPB-2H was attributed to the larger atomic size and higher electronegativity of fluorine compared to hydrogen atom. Molecular dynamics (MD) simulations demonstrated that IPB-2F2 exhibited lower permeation rates for CO2 and N2 than its non fluorinated counterpart; indicating that fluorine atoms effectively reduced gas permeation. Adsorption isotherms revealed enhanced adsorption capacities for IPB-2F2, with increased CO2 affinity resulting from strong van der Waals interactions. Selectivity analyses showed that IPB-2F2 preferentially absorbed CO2 over N2, with selectivity values consistently greater than 1. The enhanced gas uptake capacity and hydrophobicity of IPB-2F2 highlighted its potential for industrial applications as a post-combustion CO2 capture material.
Reflection Loss Improvement by Cerium Addition in Chitosan-Hydroxyapatite Film as Stealth Drone Candidate Putri, Riyanti; Prasojo, Agus Eko; Lazuardy, Ardyan; Anitasari, Reza; Salsabila, Fidela Aurellia; Sasongko, Nugroho Adi; Apriliyanto, Yusuf Bramastya; Hasibuan, Anggi Khairina Hanum; Ananda, Dea Dwi
Indonesian Journal of Chemical Studies Vol. 4 No. 1 (2025): Indones. J. Chem. Stud., June 2025
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ijcs.v4i1.53

Abstract

Radar is a detection and tracking technology commonly applied to monitor environmental conditions. Its ever-growing capabilities pose a serious challenge to military operations because they increase the risk of being detected by the enemy. On the other hand, unmanned aircraft (drones) are increasingly widespread in gathering information. However, the effectiveness of this technology can be reduced due to exposure to radar waves that allow detection. Therefore, developing coating materials that can absorb radar waves is an urgent need to increase the effectiveness of military equipment. The composites developed were derived from chitosan obtained from crustacean waste, hydroxyapatite from eggshell waste, and the rare earth metal cerium obtained from Lapindo Mud. Composites containing cerium metal (Ce) have higher radar signal absorption capabilities than samples without Ce, as evidenced by VNA measurements showing increased absorbance in the 100 MHz - 8.5 GHz frequency range. SEM tests indicate that cerium particles increase the density and homogeneity of the pore structure, with a size range of 17–24 µm. FTIR characterization revealed that Ce was physically bound to the chitosan-HAp composite. Mechanically, the composite with Ce had a maximum tensile stress of 9.512 MPa and a strain of 9.512%, while without the addition of Ce, a stress of 9.529 MPa and a strain of 25.512% was obtained. These findings indicate that integrating rare earth metals in chitosan-HAp composites can improve the material's capability to absorb radar waves, thus having broad prospects for applications in defence technology.
Sosialisasi Lingkungan Bersih serta Pengelolaan Instalasi Pengolahan Air Limbah (IPAL) di Desa Muara Angke Minandre Wiratama; Gunaryo; Mentari Zikri Anty; Mirad Fahri; Anggi Khairina H H; Elva Stiawan; Rahmat Basuki; M. Sulthon Nurharmansyah P; Tedi Kurniadi; Dewi Anggraini S; Yusuf Bramastya A; Azimatur Rahmi; Aura Puja Lestari; Moch. Rizki Fajri
Babakti: Journal of Community Engangement Vol. 2 No. 1 (2025): April
Publisher : Universitas Singaperbangsa Karawang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35706/babakti.v2i1.155

Abstract

Kesadaran Kebersihan dan Pengelolaan Sampah yang baik merupakan salah satu kebiasaan yang dapat berdampak pada kesehatan yang lebih baik. Kepedulian yang minim dalam menjaga lingkungan yang bersih diprediksi akan menimbulkan dampak buruk bagi lingkungan dan masyarakat. Selain itu, pengelolaan air bersih pada lingkungan merupakan salah satu hal yang perlu diperhatikan. Pengetahuan tentang pengolahan air bersih melalui Instalasi Pengelolaan Air Limbah (IPAL) akan memberikan dampak positif bagi keberlansungan air bersih di lingkungan masyarakat. Pengabdian kepada masyarakat ini dilakukan dengan Sosialisasi melalui pendekatan modal sosial. Pendekatan modal sosial dilakukan dalam pelaksanaan pengabdian kepada masyarakat dimana pendekatan ini digunakan sebagai wadah sosialisasi menjaga kebersihan lingkungan dan pengetahuan dalam pengolahan air bersih bagi msayarakat di Desa Muara Angke. Pengabdian kepada Masyarakat ini bertujuan untuk mensosialisasikan cara mengelola dan mengkategorikan macam-macam sampah, pengelolaan air bersih, dan desalinasi air yang dilakukan di daerah Muara Angke, Kecamatan Penjaringan, Jakarta Utara. Data dikumpulkan melalui observasi langsung dan kuesioner yang diisi oleh peserta sebelum dan sesudah program pelatihan. Hasil analisis menunjukkan bahwa kesadaran masyarakat meningkat yang dilihat dari hasil tes yang dilakukan menunjukkan peningkatan nilai dari materi yang di ujikan. Pendekatan yang tepat berhasil membangkitkan semangat dan komitmen warga yang tercermin dari tingginya tingkat partisipasi. Pelaksanaan kegiatan ini diharapkan memberikan pengetahuan dan kesadaran masyarakat dalam menjaga kebersihan lingkungan dan pengolahan air bersih.