Judul: Biodiversity of Protected Freshwater Stingray in Musi River, South Sumatera
Abstrak: Sungai Musi memiliki keanekaragaman hayati yang tinggi. Sungai Musi merupakan salah satu habitat ikan pari air tawar yang keberadaannya sangat langka dan hingga saat ini informasinya masih terbatas. Penelitian ini bertujuan untuk mendeskripsikan dan menganalisis keanekaragaman spesies ikan pari air tawar di Sungai Musi bagian tengah Provinsi Sumatera Selatan. Metode yang digunakan untuk mendeskripsikan ikan pari air tawar menggunakan pendekatan morfologis. Adapun keanekaragaman ikan pari air tawar dianalisis menggunakan pendekatan indeks keanekaragaman, indeks kemerataan, dan indeks dominansi. Ikan pari air tawar yang didapatkan sebanyak 42 ekor, yang terdiri dari enam spesies (Fluvitrygon signifer, Fluvitrygon oxyrhynchus, Fluvitrygon cf. oxyrhynchus, Fluvitrygon kittipongi, Pastinachus stellurostris, dan Urogymnus polylepis). Ikan pari air tawar di Sungai Musi memiliki kesamaan karakteristik, yaitu warna cakram dorsal kecoklatan hingga kehitaman, ekor sangat panjang seperti cambuk, terdapat 2 duri sengat, dan memiliki mata yang kecil. Hasil analisis menunjukkan bahwa keanekaragaman spesies ikan pari air tawar di Sungai Musi memiliki nilai H’= 1,38 dengan persebaran yang merata dan tak ada spesies yang mendominasi., The Musi River has a high biodiversity. The Musi River is one of the habitats of freshwater stingrays whose existence is very rare and until now the information is still limited. This study aims to describe and analyze the diversity of freshwater stingray species in the middle part of Musi River, South Sumatra Province. The method used to describe freshwater stingrays uses a morphological approach. The diversity of freshwater stingrays was analyzed using the diversity index, evenness index, and dominance index approaches. There were 42 freshwater stingrays that obtained during research, consisted of six species (Fluvitrygon signifer, Fluvitrygon oxyrhynchus, Fluvitrygon cf. oxyrhynchus, Fluvitrygon kittipongi, Pastinachus stellurostris, and Urogymnus polylepis). Freshwater stingrays in the Musi River have similar characteristics, namely brownish to blackish color of the dorsal disc, very long whip-like tail, 2 stinging spines, and small eyes. The analysis showed that the species diversity of freshwater rays in the Musi River has a value of H'= 1.38 with an even distribution and no dominant species.
Keyword: diversity, freshwater stingray, Musi River, protected

Judul: Molecular Identification of the Freshwater Stingrays Based on COI Gene Markers in Musi River, Palembang, South Sumatera
Abstrak: Ikan pari dari famili Dasyatidae memiliki karakteristik yang hampir mirip, sehingga diperlukan metode yang akurat dalam validasi spesiesnya. Selain itu, ketersediaan informasi dan data ilmiah mengenai genetik ikan pari air tawar masih minim di Indonesia. Oleh karena itu, penelitian ini bertujuan untuk mengidentifikasi spesies, kekerabatan genetik, dan keragaman genetik ikan pari air tawar berdasarkan variasi basa nukleotida Gen COI di Sungai Musi, Sumatera Selatan. Pengambilan sampel dilakukan pada bulan Februari hingga Mei 2023 di Sungai Musi. Analisis laboratorium dilakukan pada bulan Juni hingga September 2023. Ekstraksi DNA sampel menghasilkan 12 DNA total. Hasil penelitian menunjukkan dua spesies ikan pari air tawar berhasil divalidasi, yaitu Fluvitrygon signifer dan Pastinachus stellurostris dengan kemiripan 99,30% hingga 100%. Sementara itu, pari tutul (kode B) dan pari sungai tepi putih moncong panjang (kode C) belum tervalidasi secara genetik, dengan tingkat kemiripan 89,24% hingga 89,70%.Keragaman genetik ikan pari air tawar di Sungai Musi tergolong rendah, dengan rentang nilai haplotype Hd 0-0,667. Hasil konstruksi pohon filogeni menunjukkan Fluvitrygon signifer dan Pastinachus stellurostris memiliki kekerabatan jauh dengan pari tutul dan pari tepi putih moncong panjang., Stingrays from the family Dasyatidae have almost similar characteristics, so accurate methods are needed to validate the species. Apart from that, the availability of scientific information and data about the genetics of freshwater stingrays is still minimal in Indonesia. Therefore, this study aims to identify species, genetic relationships and genetic diversity of freshwater stingrays based on nucleotide base variations of the COI gene in the Musi River, South Sumatra. Sampling was carried out from June to September 2023. DNA extraction of the samples produced 12 DNAs in total. The research results showed species freshwater stingrays were successfully validated, namely Fluvitrygon signifer and Pastinachus stellurostris with 99,30% to 100% similarity. The spotted ray (code B) and the long-snouted white edge ray (code C) have not been genetically validated yet, with a similarity level of 89,24% to 89,70%. The genetic diversity of freshwater stingrays in the Musi River is relatively low, with a range of haplotype Hd values of 0-0,667. The results of the phylogenetic tree construction show Fluvitrygon signifer and Pastinachus stellurostris distantly related to marbled whipray and long-snouted white edge ray.
Keyword: COI, identifikasi morfologi, pari air tawar, sungai musi

Judul: Elektrodeposisi Film Tipis Semikonduktor Cu2ZnSnS4 (CZTS) pada Substrat Kaca ITO
Abstrak: Semiconductor Cu2ZnSnS4 (CZTS) thin film that can be used as absorber layers on solar cell module was made via electrodeposition method. CZTS thin film was electrodeposited on the surface of a silicate glass coated with a thin layer of indium tin oxide (ITO). Deposition process was done using potentiostatic mode at room temperature with a potential of 1.05 V for 30, 45, and 60 minutes, followed with annealing the film at 2 different temperatures, 500 ºC using furnace and 180 ºC using hot plate, both treatments for 45 minutes in N2/H2S atmosphere. The X-ray difractograms were analyzed using Match 2 program and showed that the CZTS thin films had kesterit crystalline structure, with a low percentage of CZTS phase. The thin film also contained secondary phases such as Cu2S, ZnS, and SnS. The obtained CZTS thin films had a thickness between 1.039 and 1.676 μm. Absorption study showed that the band gap energy of CZTS thin films which was annealed using furnace ranged from 1.50 to 1.52 eV, whereas that annealed using the hot plate was not observed. The band gap energy value showed that CZTS thin films can be used as sunlight absorber layers on solar cell. The formation of CZTS crystal film on this investigation was effectively performed using furnace annealing process at a temperature of 500 ºC with deposition time of 45 minutes.
Keyword: Thin film, Electrodeposition, Cu2ZnSnS4