The chemistry and pharmacology of citrus limonoids

Citrus limonoids (CLs) are a group of highly oxygenated terpenoid secondary metabolites found mostly in the seeds, fruits and peel tissues of citrus fruits such as lemons, limes, oranges, pumellos, grapefruits, bergamots, and mandarins. Represented by limonin, the aglycones and glycosides of CLs have shown to display numerous pharmacological activities including anticancer, antimicrobial, antioxidant, antidiabetic and insecticidal among others. In this review, the chemistry and pharmacology of CLs are systematically scrutinised through the use of medicinal chemistry tools and structure-activity relationship approach. Synthetic derivatives and other structurally-related limonoids from other sources are include in the analysis. With the focus on literature in the past decade, the chemical classification of CLs, their physico-chemical properties as drugs, their biosynthesis and enzymatic modifications, possible ways of enhancing their biological activities through structural modifications, their ligand efficiency metrics and systematic graphical radar plot analysis to assess their developability as drugs are among those discussed in detai

PENGEMBANGAN MEDIA PEMBELAJARAN TEKS CERAMAH UNTUK KELAS XI SMAN 1 MENTAYA HILIR UTARA KOTAWARINGIN TIMUR - KALIMANTAN TENGAH

Abstrak: Meningkatnya perkembangan teknologi berdampak pada lajunya pengolaha informasi. Pertumbuhan teknologi berpengaruh besar terhadap pentingnya sumber daya agar penggunaannya dapat memberikan manfaat yang baik. Terlebih lagi saat wabah Covid 19, dimana aktivitas belajar mengajar dilakukan secara daring. Selama masa pandemi ini pendidik  dan peserta didik dapat memanfaatkan kemajuan teknologi untuk menerima dan memberi pembelajaran.  Namun, Pembelajaran secara jarak jauh atau e-learning selama pandemi Covid 19 dapat membuat peserta didik merasa kurang termotivasi. Selain itu, pendidik juga dapat merasakan kebingungan tentang penyajian materi pembelajaran mereka. Media dapat digunakan sebagai bahan belajar alternatif yang dapat membuat pembelajaran menjadi kegiatan yang menyenangkan. Hal ini selaras dengan pendapat dari Ahmad sudrajat menyatakan bahwa media adalah sesuatu yang dapat menyampaikan pesan dan dapat menstimulus perasaan, pikiran, dan keinginan peserta didik sehingga termotivasi dalam proses belajar. Latar belakang dilakukan penelitian ini adalah media pembelajaran berbasis elektronik merupakan salah satu kebutuhan peserta didik masa kini serta penyampain materi teks ceramah tidak cukup hanya dengan menggunakan media gambar dan teks. Akan lebih menarik jika terdapat video yang membantu secara visual.Tujuan penelitian ini untuk mendeskripsikan kebutuhan guru dan peserta didik terhadap media pembelajaran teks ceramah, menjelaskan tentang proses pengembangan media pembelajaran menganalisis teks ceramah, mendeskripsikan kelayakan media pembelajaran menganalisis teks ceramah.Model pengembangan yang diterapkan di penelitian ini adalah model dari Borg and Gall yang memiliki 4 tahapan, yaitu pertama pengumpulan informasi, kedua perencanaan, ketiga pengembangan produk, dan keempat adalah validasi dan uji coba. Uji coba produk skala kecil dilakukan dengan jumlah 18  peserta  didik dan seorang guru. Teknik pengumpulan data menggunakan angket validasi. Kemudian data dianalisis dengan menggunakan teknik analisis kalitatif dan kuantitatif.Hasil penelitian menunjukkan dengan tingkat persentase 78,3 % guru setuju apabila diadakan pengembangan terhadap media pembelajaran teks ceramah bagi peserta didik kelas XI SMAN 1 Mentaya Hilir Utara. Selain itu, peserta didik juga menyatakan 66,7% sangat setuju bahwa penyampaian materi teks ceramah tidak cukup hanya dengan menggunakan media gambar dan teks. Akan lebih menarik jika terdapat video yang membantu secara visual. Selama proses pengembangan terdapat 3 tahapan yang harus dilakukan yaitu, membuat naskah rekaman, membuat rekaman video, mengedit video dengan menggunakan aplikasi Wondershare Filmora9 untuk menambahkan tulisan, tampilan, suara dan durasi sehingga video dapat disajikan. Hasil validasi dari ahli materi tingkat persentase  yang diperoleh adalah 87,50 % sedangkan dari ahli media tingkat persentase  yang diperoleh adalah 82,50 %. Dari hasil validasi yang diperoleh menunjukkan bahwa produk media pembelajaran teks ceramah peserta didik kelas XI SMAN 1 Mentaya Hilir Utara valid dan layak diimplementasikan dengan sedikit revisi. Pada respon guru menunjukkan tingkat persentase  90 %,  sedangkan pada respon peserta didik tingkat persentase yang diperoleh adalah  94,44 % peserta didik menyatakan sangat setuju jika media membuat materi teks ceramah gampang dicerna dan efektif digunakan dalam pembelajaran teks ceramah. Dari hasil validasi yang diperoleh disimpulkan bahwa media pembelajaran teks ceramah sudah layak dan dapat diimplementasikan tanpa perbaikan . Kata kunci : Media Pembelajaran, Video Pembelajaran , Teks Ceramah

Monolithic multifinger lateral nanodiamond electron emission devices

Chemical-vapor-deposited (CVD) diamond is an excellent electron emission material due to its low electron affinity, robust mechanical and chemical properties, high thermal conductivity, and ability to withstand high temperature and radiation. Nanocrystalline diamond, also known as nanodiamond, is an emerging form of CVD diamond which vastly expanding its applicability in vacuum electronics. Apart from the assets of the conventional CVD diamond, it possesses certain distinct properties which include smaller grain-size, high volume density of grain-boundaries, smoother surface morphology, n-type dopant incorporation and increased sp2-carbon content. However, the utilization of nanodiamond in vacuum micro/nanoelectronics has been limited by the complexity associated with its process integration. The purpose of my research is to develop a reliable process technique to fabricate efficient nanodiamond lateral electron emission devices operable at low voltage with high emission current for applications in vacuum microelectronics and integrated-circuits. To achieve this goal, first, a well-controlled process to realize useful and potential nanodiamond electron emitter structures in array configurations using electron beam lithography (EBL) and plasma etching techniques has been developed. Detail study includes optimization of processing parameters for EBL, metal-mask deposition and nanodiamond dry etching. The main part of the research includes the application of these recently developed process techniques for the design, fabrication and characterization of micro/nanopatterned nanodiamond lateral field emission devices which include sub-micron gap two-terminal and multifinger three-terminal structures. 140-fingered nanodiamond lateral diode has been achieved for the first time with 300nm interelectrode distance. On the other hand, the three-terminal structure is composed of 140 finger-like emitters with integrated anode and gate, which also has never been reported before. The electrical characteristics of these fabricated nanodiamond vacuum lateral field emission devices demonstrated promising behavior with very low turn-on voltage with high and stable emission current. It has also been observed for the first time that three emission mechanisms dominated at different potential levels. The three-terminal structure showed anode current enhancement and suppression behavior by changing gate bias. These developments in the field of nanotechnology signify the integration of vacuum electronics with the well-established IC process techniques favorable for high-speed and high-power, IC-compatible, extreme-environment vacuum micro/nanoelectronics applications

CNT field emission cell with built-in electron beam source for electron stimulated amplified field emission

Carbon Nanotube (CNT) is an emerging form of carbon nanostructure, vastly expanding its utility for several applications ranging from electronics to tribology. CNT is an excellent material for electron field emission due to its high aspect ratio, robust mechanical and chemical properties, high thermal conductivity, and ability to withstand high temperature and ion bombardment. This research is focused on the fabrication and characterization of a novel CNT field emission cell with a built-in electron beam source for electron excited amplified field emission. In brief, reliable and consistent process techniques have been developed to grow aligned CNTs under different growing conditions using MPCVD. This process was integrated in the fabrication of monolithic lateral field emission cell (FEC) in diode configuration with a built-in electron beam source. Field emission behaviors with and without activation of the built-in electron beam were characterized. A high voltage of 1.8 kV was applied to generate the bombarding electron beam on the FEC. The emission current of the FEC increases markedly with the activation of the electron beam source due to impact ionization and direct interaction with the FEC CNT cathode. The emission behaviors were confirmed by F-N plots. It was found that ~ 10 times current amplification was achieved. These results demonstrate the feasibility of a novel means of power generation using electron stimulated impact ionization field emission

Enhanced Supercapacitor Using 3-D CNT/MnO₂ Webs Hanging on Silicon Micro-Pillars

Abstract not Available.</jats:p