Judul: Sintesis nanokalsium dan formulasi pasta gigi dengan nanokalsium dan kitosan
Abstrak: Penyerapan kalsium dapat ditingkatkan dengan konsumsi kalsium berukuran nano. Limbah crustaceae dapat diekstrak dan dipresipitasi untuk menghasilkan nanokalsium. Pasta gigi merupakan produk non-pangan dengan kalsium tinggi. Pasta gigi komersil memiliki fluor dan sodium lauril sulfat (SLS) yang memiliki efek negatif terhadap lingkungan dan tubuh. Tujuan penelitian ini adalah menentukan pengaruh pH presipitasi terhadap karakteristik nanokalsium dan melakukan formulasi pasta gigi dengan penambahan nanokalsium dan kitosan. Limbah diekstrak dengan HCl dan dipresipitasi dengan perlakuan pH (8, 10, 12) menggunakan NaOH. Nanokalsium yang terbentuk dikarakterisasi dan diaplikasikan dalam formulasi pasta gigi. Konsentrasi nanokalsium dalam pasta gigi adalah 0.5%, 0.75% dan 1% (b/b) dan konsentrasi kitosan 2% dalam pasta gigi adalah 0.5% dan 1% (v/v). Rendemen nanokalsium dengan presipitasi pH 12 adalah 16.43%. Kadar kalsium pada serbuk sebesar 14.07%. Ukuran partikel nanokalsium berada pada kisaran 145.85 sampai 343.60 nm. Formulasi B adalah kombinasi konsentrasi kitosan 2% sebesar 0.5% dan nanokalsium sebesar 0.5%. Formulasi B memiliki nilai kuat tekan dan pH berturut-turut sebesar 5.32 MPa dan 7.54. Warna gigi pada formulasi B cerah. Warna pasta yang dihasilkan berwarna putih keruh. Homogenitas pasta dinilai cukup baik. Parameter pH, warna pasta, homogenitas, dan tekstur telah memenuhi standar SNI
Keyword: chitosan, nanocalcium, precipitation, toothpaste

Judul: Formulasi Pasta Gigi Biomimetik Hidroksiapatit-ZnO dari Limbah Cangkang Keong Sawah
Abstrak: Pasta gigi merupakan suatu sediaan untuk perawatan gigi dalam rangka membersihkan, memperindah, dan mengganti mineral yang meluruh dari permukaan gigi. Pencegahan kerusakan lapisan mineral pada gigi dilakukan melalui penambahan agen remineralisasi pada sediaan pasta gigi, yaitu berupa komposit hidroksiapatit-ZnO. Penelitian ini bertujuan menyintesis dan mengkarakterisasi hidroksiapatit-ZnO, serta melakukan formulasi pasta gigi hidroksiapatit-ZnO dari limbah cangkang keong sawah. Komposit hidroksiapatit-ZnO telah berhasil disintesis menggunakan metode sol gel dan dilakukan pencirian menggunakan X-ray diffraction (XRD), fourier transform infrared (FTIR), dan scanning electron microscope-energy dispersive X-ray (SEM-EDX). Hasil XRD menunjukkan ukuran kristal sebesar 59,90 nm dengan persentase kristalinitas 68,85%. Pita serapan pada bilangan gelombang 452 cm¬-1 mengindikasikan senyawa ZnO yang telah berhasil dikompositkan dengan hidroksiapatit. Analisis SEM-EDX menunjukkan morfologi senyawa berupa granular dengan permukaan kasar dengan ukuran dan bentuk yang tidak merata. Hasil formulasi pasta gigi hidroksiapatit-ZnO pada formula 45% memiliki stabilitas fisik yang baik dibandingkan dengan formula lainnya. Sifat antibakteri sediaan pasta gigi hidroksiapatit-ZnO menunjukkan daya hambat yang sangat kuat pada bakteri Streptococcus mutans.
Keyword: antibacterial, hydroxyapatite-ZnO, rice snail shell, toothpaste

Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite