Penyesuaian Impedansi Antena Open Dipole RF 217 MHz Menggunakan Metode Single Stub

Penyesuaian impedansi merupakan suatu masalah yang sangat penting untuk diperhatikan pada saat menginstalasi antena suatu pemancar. Gelombang yang dipantulkan kembali ke pemancar akan mengakibatkan panas dan kerusakan pada penguat akhir pemancar, sehingga menyebabkan penurunan daya atau daya yang dihasilkan oleh pesawat pemancar tidak akan maksimal. Penelitian dilakukan untuk mengetahui seberapa besar impedansi antena berkontribusi pada matching impedance (penyesuaian impedansi), menggunakan metode single stub tuner. Hasilnya adalah Pada pengukuran yang menggunakan kabel koaksial RG-55 A/U, posisi paling match terjadi pada jarak 30 cm dari antena ke arah generator sehingga stub dipasang secara permanen pada jarak tersebut, sedangkan  pada pengukuran yang menggunakan kabel koaksial 5D-2W, posisi paling match terjadi di antena itu sendiri dan tidak ditemukan posisi match pada saluran sehingga stub tidak dipasang. Pada kabel koaksial RG-11/U, posisi paling match terjadi pada jarak 20 cm dari antena ke arah generator sehingga stub dipasang secara permanen pada jarak tersebut.

Two new prenylated chalcones from the leaves of Artocarpus lowii King

Two minor prenylated chalcones were isolated for the first time from the leaves of Artocarpus lowii King. These prenylated chalcones were identified as 2- hydroxyparatocarpin C (1) and 2ʹ,3,4ʹ,4-tetrahydroxy-3ʹ-prenylchalcone (2). The structures of these prenylated chalcone were elucidated by utilizing the data values obtained from1H NMR,13C NMR, DEPT, COSY, IR, UV and MS, as well as by comparison with literature values

Flavonoids and triterpenes from the leaves of artocarpus fulvicortex

Five flavonoids, 5-hydroxy-(6:7,3:4)-di(2,2- dimethylpyrano)flavone 1, carpachromene 2, cycloartocarpesin 3, norartocarpetin 4 and 2′-hydroxy-4,4′,6′- trimethoxychalcone 5, along with three triterpenes, friedelin 6, lupeol 7 and β-sitosterol 8 were isolated for the first time from the leaves of Artocarpus fulvicortex F.M. Jarrett. The structures of these compounds were established by analysis of their spectroscopic (1D and 2D NMR) and spectrometric (MS) data, as well as by comparison of these with those reported in the literature

Cholinesterase inhibitors from heartwood of artocarpus fulvicortex F. M. Jarret (Moraceae)

Cholinesterase inhibition activities were screened on crude extracts and isolated compounds of the heartwood of Artocarpus fulvicortex. Phytochemical studies on the heartwood of A. fulvicortex have resulted in the isolation of one flavonoid, one stilbenoid and two triterpenes. Their structures were determined by spectroscopic analysis as catechin (1), oxyresveratrol (2), lupeol-3-acetate (3) and friedelin (4). All isolates were evaluated for the first time for anti-cholinesterase activity. Inhibition of acetylcholinesterase (AChE), tested by Ellman’s method and modified TLC bioautographic assay showed catechin (1) and oxyresvetratrol (2) were active agents with detection limit of 2 mM. The microplate assay was carried out using butyrylcholinesterase (BChe) to further confirmed that catechin (1) and oxyresvetratrol (2) displayed positive cholinesterase activity with IC50 values 50.0 mM and 6.25 mM respectively in dose dependent manner

Tingkat Infestasi Koksidiosis (Eimeria sp.) pada Kerbau Lumpur (Bubalus bubalis Linn.) di Kecamatan Jati Agung Kabupaten Lampung Selatan

Infestasi parasit pada saluran pencernaan kerbau lumpur dapat mengganggu kesehatan ternak. Penelitian ini bertujuan untuk mengetahui tingkat infestasi protozoa saluran pencernaan (Eimeria sp.) pada kerbau lumpur (Bubalus bubalis Linn.) di Kecamatan Jati Agung, Kabupaten Lampung Selatan yang dapat menjadi tambahan informasi bagi pemerintah daerah khususnya peternak untuk melakukan pencegahan dan pengendalian penyakit akibat infestasi protozoa. Penelitian ini dilakukan dengan menggunakan metode survei. Sebanyak 80 sampel feses kerbau lumpur dikoleksi selama Desember 2019 di 6 Desa di Kecamatan Jati Agung. Data yang digunakan berupa data primer tentang manajemen pola pemeliharaan yang diambil dengan menggunakan kuesioner dan hasil pemeriksaan sampel feses terhadap jumlah ooskista protozoa saluran pencernaan (Eimeria sp.). Tingkat infestasi koksidiosis akibat protozoa Eimeria sp. pada kerbau lumpur (Bubalus bubalis Linn.) di Kecamatan Jati Agung Kabupaten Lampung Selatan sebesar 17,50% dengan jumlah ookista protozoa Eimeria sp. dalam tinja termasuk dalam kategori infestasi ringan. Rendahnya infestasi koksidiosis (Eimeria sp.) pada kerbau lumpur ini kemungkinan berkaitan erat dengan adanya pelayuan dari pakan (rumput) sebelum diberikan ke ternak

Phytochemistry and antioxidant activity of garcinia prainiana

Phytochemical investigation of the leaves and stem bark of G. prainiana was carried out. The leaves and stem barks of G. prainiana collected from Kuantan, Pahang were extracted by soxhletextractorwith hexane, dichloromethane and methanol to get the crude exkacts. The crude extracts were purified by column chromatography io yield pure compounds which were characterized spectroscopically using lR, NMR (1D and 2D), UV and MS. Fractionation and purification of the hexane extract of leaves yielded triterpenes, squalene and friedelin. The methanol extract of leaves and stem barks afforded bioflavonoid characterized as morelloflavone and O-methyl fukugetin. Total phenolic content studies were carried out on the crude extracts by using Folin-Ciocalteau reagent. The methanol extract of leaves and stem barks showed the highest total phenolic content expressed as gallic acid and (t)-catechin equivalents. These extracts also showed the highest value of ascorbic acid and butylated hydroxytoluene (BHT) equivalents on forming the phosphomolybdenum complex in the total antioxidant assay. The antioxidant assay on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical showed that the methanolextract of stem barks had the highest free radical scavenging activity with lCso value 74.5trr9/ml while the isolated compound, morelloflavone revealed a strong free radical scavenging activity with lCsovalue 15.7p9/m

[μ2-Bis(diphenylphosphanyl)hexane]bis[undecacarbonyl-triangulo-triruthenium(3 Ru—Ru)] hexane monosolvate: crystal structure and Hirshfeld surface analysis

In the title cluster complex hexane solvate, [Ru6(C30H32P2)(CO)22]·C6H14, two Ru3(CO)11 fragments are linked by a Ph2P(CH2)6PPh2 bridge with the P atoms equatorially disposed with respect to the Ru3 triangle in each case; the hexane solvent mol­ecule is statistically disordered. The Ru...Ru distances span a relatively narrow range, i.e. 2.8378 (4) to 2.8644 (4) Å. The hexyl chain within the bridge has an all-trans conformation. In the mol­ecular packing, C—H...O inter­actions between cluster mol­ecules, and between cluster and hexane solvent mol­ecules lead to a three-dimensional architecture. In addition, there are a large number of C[triple bond]O...π(arene) inter­actions in the crystal. The importance of the carbonyl groups in establishing the packing is emphasized by the contribution of 53.4% to the Hirshfeld surface by O...H/H...O contacts

Rancang Bangun Perangkat Lunak Sistem Auto Tracking Satellite Antenna Mobile Menggunakan Metode Azimut-elevasi Dan Koreksi Modem

Software Design of Mobile Antenna for Auto Satellite Tracking using Modem Correction and Elevation AzimuthMethod. Pointing accuracy is an important thing in satellite communication. Because the satellite’s distance to thesurface of the earth\u27s satellite is so huge, thus 1 degree of pointing error will make the antenna can not send data tosatellites. To overcome this, the auto-tracking satellite controller is made. This system uses a microcontroller as thecontroller, with the GPS as the indicator location of the antenna, digital compass as the beginning of antenna pointingdirection, rotary encoder as sensor azimuth and elevation, and modem to see Eb/No signal. The microcontroller useserial communication to read the input. Thus the programming should be focused on in the UART and serialcommunication software UART. This controller use 2 phase in the process of tracking satellites. Early stages is themethod Elevation-Azimuth, where at this stage with input from GPS, Digital Compass, and the position of satellites(both coordinates, and height) that are stored in microcontroller. Controller will calculate the elevation and azimuthangle, then move the antenna according to the antenna azimuth and elevation angle. Next stages is correction modem,where in this stage controller only use modem as the input, and antenna movement is set up to obtain the largest valueof Eb/No signal. From the results of the controller operation, there is a change in the value of the original input levelfrom -81.7 dB to -30.2 dB with end of Eb/No value, reaching 5.7 dB