Judul: Analysis of Critical Buckling Height of Standing  Trees and Palm Under Self-weight Loading
Abstrak: Pohon berpotensi tumbang akibat ketidakstabilan tekuk. Tekuk adalah suatu peristiwa ketika struktur kolom tidak mampu lagi mempertahankan bentuk lurus seperti aslinya. Penelitian ini bertujuan menganalisa keamanan pohon berdiri dan palma yang diamati sebagai kolom bundar langsing yang menerima beban tekan. Keamanan palma dan pohon berdiri dikategorikan menjadi kondisi tidak aman (Sf ≤ 1,00), cukup aman (1,00 < Sf ≤ 1,645), aman (1,645 < Sf ≤ 2,326), dan sangat aman (Sf > 2,326). Tinggi tekuk kritis dihitung berdasarkan : (1) analisis struktur rumus tekuk Euler dan rumus tekuk Ylinen, (2) rumus Greenhill tanpa tajuk, dan (3) modifikasi rumus Greenhill untuk mengakomodasi berat tajuk. Hasil penelitian menunjukkan tinggi tekuk kritis terendah untuk trembesi dan palem raja dihasilkan dari metode tegangan tekuk Euler dan Ylinen sedangkan untuk agathis dihasilkan dari metode Greenhill yang dimodifikasi. Perbedaan hasil tersebut dimungkinkan karena perbedaan bentuk pertumbuhan. Penelitian ini menunjukkan persentase jumlah palem raja yang berada pada kondisi cukup aman (35%), aman (35%), dan sangat aman (30%). Persentase jumlah agathis berada pada kondisi cukup aman (73,91%), dan aman (26,09%); sedangkan persentase jumlah trembesi berada pada kondisi tidak aman (26%), cukup aman (58%), dan aman (16%). Penelitian ini merekomendasikan pemangkasan ringan bagi pohon yang termasuk dalam kondisi tidak aman., Trees have the potential to fall due to buckling instability. Buckling is an event when the structure of the column is no longer able to maintain its original shape. This study aims to analyze the safety of standing trees and palms which are observed as round columns that undergoes compressive stresses. The safety analysis of palms and standing trees is categorized into unsafe conditions (Sf ≤ 1,00), moderately safe (1,00 < Sf ≤ 1,645), safe (1,645 < Sf ≤ 2,326), and very safe (Sf > 2,326). The critical buckling height is calculated based on : (1) The structural analysis of the Euler and Ylinen buckling formula, (2) The Greenhill formula without crown, and (3) The modification of the Greenhill formula to accommodate the weight of the crown. The results showed that the lowest critical buckling height for rain tree and royal palm was produced using the Euler and Ylinen buckling stress methods while for agathis was produced using the modified Greenhill method. The differences in results is possible due to differences in the growth forms. This study showed the observed royal palm were in a moderately safe (35%), safe (35%), and very safe (30%). Meanwhile, agathis is in a moderately safe (73,91%), and safe (26,01%); while rain tree is in an unsafe condition (26%), moderately safe (58%), and safe (16%). This study recommends mild pruning for trees that are in unsafe conditions.
Keyword: growth form, Tree Biomechanics, Greenhill, column, buckling

Judul: Analisis Kekuatan Tekuk Kolom Bambu Tali (Gigantochloa apus (J.A. & J.H. Schultez) Kurz) dengan Variasi Panjang dan Jumlah Batang Penyusun Kolom
Abstrak: Bambu tali berpotensi dijadikan sebagai kolom. Tekuk merupakan titik kritis penyebab kegagalan struktur kolom dalam menahan beban tekan. Penelitian ini bertujuan mengetahui kekuatan tekuk maksimum kolom bambu tali dengan variasi panjang dan jumlah batang penyusun. Bambu tali diperoleh dari pasar komersial di Jl. Raya Dramaga, Bogor, Jawa Barat. Bambu dipotong menjadi ukuran 1, 2, dan 3 m. Pengukuran dimensi berdasarkan BS ISO 19624:2018, sedangkan pengukuran geometri berdasarkan BS ISO 22157:2019. Pengujian sifat fisis meliputi kadar air, kerapatan, dan kerapatan linear, serta pengujian mekanis yaitu kekuatan tekuk kolom bambu tali. Uji lanjut Duncan digunakan untuk membandingkan hasil pengujian tekuk kolom bambu tali dengan variasi panjang dan jumlah batang penyusun kolom. Contoh kolom berukuran 1 m, 2 m, dan 3 m. Pengujian tekuk kolom 1 m mengunakan UTM SATEC-Baldwin berkapasitas 30 ton, sedangkan pengujian tekuk kolom 2 m dan 3m menggunakan alat uji tekan berkapasitas 100 ton. Pengujian tekuk kolom dilakukan dengan memberikan pembebanan secara vertikal pada kolom. Pengolahan data faktor tekuk menggunakan Formula Ylinen’s. Kolom bambu panjang memiliki angka kelangsingan tinggi dan menghasilkan nilai tekuk rendah, sehungga kolom mudah mengalami tekuk. Kolom bambu tali komposisi ganda dua, tiga, maupun empat memiliki nilai kekuatan tekuk lebih tinggi dibandingkan jumlah kekuatan tekuk masing-masing batang penyusunnya karena adanya kerjasama antar komponen penyusun. Peningkatan kekuatan akibat kerjasama antar komponen penyusun ini dapat dinyatakan sebagai repetitive member factor (komponen struktur berulang) yang masih perlu diperhitungkan., Bamboo tali has the potential to be used as a column. Buckling is a critical point that causes the failure of the column structure to withstand compressive loads. This study aims to determine the maximum buckling strength of the bamboo tali column with variations in length and number of comonents. The bamboo tali was obtained from commercial market on Jl. Raya Dramaga, Bogor, West Java. The bamboo is cut into 1, 2, and 3 meters. Dimensional measurements are based on BS ISO 19624:2018, while geometric measurements are based on BS ISO 22157:2019. Physical properties tests include moisture content, density, and linear density, as well as mechanical testing, namely the buckling strength of the bamboo tali column. Duncan's further test was used to compare the results of the buckling test of bamboo tali columns with variations in length and number of components making up the column. The column test speciments are 1 m, 2 m, and 3 m. The 1 m sized columns are tested using UTM SATEC-Baldwin 30 tons capacity, while the 2 m and 3 m sized column were tested using compressive testing machine 100 tons capacity. The column buckling test is carried out by applying vertical loading to the column. Buckling factor data processing using Ylinen's Formula. Long bamboo columns have a high slenderness rate and produce a low buckling value, so that the column is prone to buckling. The the buckling strength of bamboo multicolumns are higher than the sum of single colunms buckling strengths because of the cooperation between the column’s components. The strength improvement because of the column’s components cooperation can be determined as repetitive member factor which should be considered.
Keyword: angka kelangsingan, kolom, multikolom, tali, tekuk, slenderness ratio, column, multicolumns, tali, buckling

Judul: Isolasi Konstruksi dan Rekombinasi Gen Pengkode Reverse Transcriptase asal Simian Retrovirus-2 (SRV-2)
Abstrak: The availability of reverse transcriptase enzym as a valuable component for Reverse Transcription Polymerase Chain Reaction (RT-PCR) technique has been providing by foreign companies. Therefore, it needs more cost and time to provide it. This study is an early step to produce in house reverse transcriptase rekombinant enzym from SRV-2. The purpose of this study was isolated, constructed, and rekombined SRV-2 reverse transcriptase gene to entry clone and destination vector. Isolation was done by PCR amplification technique using three pairs of primers, which are RT I (3282-3683), RTII (3261-3900), and RTIII (3169-4133). Construction and recombination in this study used Gateway method from Invitrogen. SRV-2 reverse transcriptase gene was isolated in this study with A-549 cell inoculated SRV-2 as source of virus. This gene amplify by PCR technique and resulted specific band for RTI 401 bp, RTII 639 bp, and RTIII 964 bp. Analysis of pENTR/SD/TOPO and pDEST17 indicated SRV-2 reverse transcriptase gene code has already inserted to this plasmid. This result indicated SRV-2 reverse transcriptase gene have isolated, constructed, and recombined to entry clone and destination vector.
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