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All Journal Indonesian Journal of Chemistry Journal of Community Service and Empowerment Indonesian Journal of Chemical Studies (Indones. J. Chem. Stud.)
Putri, Riyanti
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Chemical Engineering, Chemistry & Bioengineering Chemistry Social Sciences Other

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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.
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.
Copolymerization of Tapioca Starch Waste through Grafting of Acrylic Acid Monomer with Cerium(IV) Initiator as Super Absorbent Polymer (SAP) Candidate Kurniadi, Tedi; Prasojo, Agus Eko; Putri, Riyanti; Nurwanto; Hartono, Rudi; Atmadi
Indonesian Journal of Chemical Studies Vol. 4 No. 2 (2025): Indones. J. Chem. Stud. December 2025
Publisher : Indonesian Scholar Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55749/ijcs.v4i2.81

Abstract

Indonesia, one of the world's largest tapioca starch producers, generates abundant cassava starch waste (onggok) that remains underutilized. This study aimed to enhance the value of onggok by synthesizing a superabsorbent polymer (SAP) through graft copolymerization using acrylic acid monomer and cerium(IV) initiator. Grafting was optimized by varying monomer concentrations (10–40% w/w) while maintaining the initiator concentration at 1.70% (w/w) and a reaction temperature of 53 °C. The optimal grafting occurred at 20% monomer concentration, yielding a grafting percentage of 14.83% and a monomer conversion of 74.15%. FTIR analysis showed increased absorbance ratios of –OH to C=O functional groups, confirming successful grafting. SEM images revealed a transformation from granular to porous structures, while DSC analysis demonstrated a shift in gelatinization temperature from 45.91 °C (raw onggok) to 46.69 °C (grafted), and retrogradation temperature from 140.67 °C to 141.67 °C. The water absorption capacity of the grafted copolymer reached 4.2450 g/g (5.20 g total), nearly double that of raw onggok (2.2716 g/g or 3.20 g), confirming its effectiveness as a SAP material.
Co-Authors Ananda, Dea Dwi ANGGI KHAIRINA HANUM HASIBUAN Anitasari, Reza Arief Budi Santiko, Arief Budi ARIYANTI, DITA Atmadi Bolilanga, Patricya Inggrid Wilhelmina Elva Stiawan Fahri, Mirad Hartono, Rudi Kurniadi, Tedi Lazuardy, Ardyan Mayori, Ersha Nugroho Sasongko Jati, Nugroho Sasongko Nurrosyid, Naufan Nurwanto Prasojo, Agus Eko Putra, M. Sulthon Nurharmansyah Rahmat Basuki Salsabila, Fidela Aurellia Septaningsih, Dewi Tiarani, Sekar Ilma Wiana, Regita Andriani Yunita, Amalia Yusuf Bramastya Apriliyanto