Skrining Fitokimia Metabolit Sekunder Ekstrak Metanol dari Kulit Batang Mahoni (Swietenia Mahagony Jacq.)

Mahoni Jawa (Swietenia mahagon Jacq.) merupakan tanaman yang banyak tumbuh dan telah dibudidayakan di Indonesia. Namun masih sangat terbatas kajian terhadap senyawa-senyawa metabolit sekunder sebagai penyusunnya. Paper ini melaporkan hasil skrining metabolit sekunder bagian kulit batang kayu mahoni. Metode yang digunakan adalah ekstraksi menggunakan soxhlet serta melakukan uji fitokimia dengan beberapa reagen pendeteksi senyawa metabolit sekunder. Hasil analisis menunjukkan bahwa kulit kayu mahoni jawa mengandung senyawa metabolit sekuder golongan alkaloid, flavonoid, saponin, fenolik hidrokuinon, dan tanin

Studi Waktu Reaksi Kondensasi terhadap Sintesis Senyawa Turunan Furfural dengan 2-butanon

Penelitian ini bertujuan untuk sintesis senyawa turunan furfural melalui reaksi kondensasi aldol (Claisen-Schmidt) dari bahan dasar furfural dengan 2-butanon. Reaksi kondensasi dilakukan pada suhu ruang dengan variasi waktu reaksi 4, 8, dan 16 jam dengan katalis basa NaOH 10%. Furfural yang dipakai adalah furfural standar dan furfural hasil isolasi dari tongkol jagung dengan kemurnian 96%. Reaksi kondensasi menggunakan furfural standar selama 4, 8, dan 16 jam menghasilkan produk sebesar 15,42%, 37,92%, dan 55% (b/b). Reaksi yang sama menggunakan furfural hasil isolasi menghasilkan produk sebesar 64%, 85%, 97% (b/b). Hal ini menunjukkan bahwa waktu reaksi berpengaruh terhadap persentase produk yang dihasilkan. Bertambahnya waktu reaksi dari 4 jam ke 16 jam meningkatkan rendemen produk sampai 97%. Senyawa turunan furfural yang dapat diidentifikasi dari analisis menggunkan UV-Vis, IR, dan 1H-NMR adalah 5-furanil-4-penten-2-on dan 5-furanil-3-metil-3-buten-2-on

Scaling laws in tube lattice fibers

Scaling laws of confinement loss and dielectric overlap in circularly arranged tube lattice fibers are numerically analyzed. Confinement loss scales as the 4.5 power of wavelength-core size ratio whereas dielectric overlap dependence is weaker

Confinement loss scaling law analysis in tube lattice fibers for terahertz applications

The development of low loss, small size and flexible waveguides is one of the most challenging issues of THz research due to the poor characteristics of both metal and dielectrics in this frequency range. Hollow core tube lattice fibers (HCTLFs) have been recently proposed and experimentally demonstrated to overcome this problem. However, they require very large hollow core size leading to big and hardly flexible fibers. Scaling law analysis plays an important role in determining the best trade-off between low loss and small fiber diameter. The dependence of the confinement on frequency and core radius are here numerically investigated. Results show that confinement loss exhibits a stronger dependence on core size and frequency with respect to other hollow core fibers proposed for THz waveguiding, such as Bragg, Tube, and Kagome fibers

Original Research by Young Twinkle Students (Orbyts): Ephemeris Refinement of Transiting Exoplanets II

We report follow-up observations of four transiting exoplanets, TRES-2b, HAT-P-22b, HAT-P-36b and XO-2b, as part of the Original Research By Young Twinkle Students (ORBYTS) programme. These observations were taken using the Las Cumbres Observatory Global Telescope Network's (LCOGT) robotic 0.4 m telescopes and were analysed using the HOlomon Photometric Software (HOPS). Such observations are key for ensuring accurate transit times for upcoming telescopes, such as the James Webb Space Telescope (JWST), Twinkle and Ariel, which may seek to characterise the atmospheres of these planets. The data have been uploaded to ExoClock and a significant portion of this work has been completed by secondary school students in London