Judul: Soil Strength over Various Land Use and Slopes (Case Study: PT. Perkebunan Buah Subang)
Abstrak: Areal perbukitan dan pegunungan berpotensi mengalami longsor karena cenderung memiliki lereng yang curam. Terjadinya longsor erat kaitannya dengan kekuatan tanah. Kekuatan tanah merupakan parameter yang menggambarkan kemampuan tanah menahan tekanan tanpa mengalami kegagalan. Penelitian yang bertujuan untuk mengidentifikasi kekuatan tanah pada lahan terbuka, kebun bambu, dan hutan dengan kemiringan lereng berbeda, serta mengetahui hubungannya dengan sifat-sifat fisik dan kandungan bahan organik tanah, dan mengetahui pengaruh kehadiran perakaran tanaman terhadap kekuatan tanah telah dilakukan di daerah PT. Perkebunan Buah Subang. Penelitian dilakukan pada lahan terbuka, kebun bambu, dan hutan dengan kemiringan lereng 15-30% dan 30-45%. Parameter kekuatan tanah yang diukur di lapang adalah ketahanan penetrasi dan kekuatan geser tanah. Sifat-sifat fisik dan kandungan bahan organik yang mempengaruhi kekuatan tanah dianalisis di laboratorium. Kekuatan tanah berbeda-beda pada berbagai penggunaan lahan dan kemiringan lereng. Lokasi kebun bambu kemiringan lereng 15-30% dan 30-45% menunjukkan nilai kekuatan geser yang lebih tinggi dibandingkan lokasi lainnya. Kekuatan geser tanah pada lokasi kebun bambu lebih tinggi karena sistem perakarannya serabut yang terjalin satu sama lain dalam mengikat matrik tanah sehingga tanah menjadi lebih kuat dalam menahan keruntuhan. Ketahanan penetrasi dipengaruhi oleh kandungan bahan organik, jumlah diameter agregat paling besar (≥ 2 mm), bobot isi tanah, dan porositas total tanah. Semakin tinggi persentase diameter agregat berukuran ≥ 2 mm, kandungan bahan organik, dan porositas total, serta semakin rendah bobot isi tanah akan menyebabkan ketahanan penetrasi semakin rendah. Kekuatan geser dan ketahanan penetrasi tanah pada lokasi dengan penggunaan lahan kebun bambu, baik pada kemiringan lereng 15-30% maupun pada kemiringan lereng 30-45% menunjukkan adanya trend penurunan nilai pada jarak yang semakin menjauhi tanaman bambu. Kata kunci: jarak, kekuatan geser, ketahanan penetrasi, perakaran, sifat fisik., Hilly and mountainous areas have the potential to experience landslides because they tend to have steep slopes. The occurrence of landslides is closely related to soil strength. Soil strength is a parameter that describes the ability of the soil to withstand pressure without experiencing failure. A research aims at identifying soil strength in open land, bamboo gardens, and forests with different slopes, as well as to determine their relationship to soil physical properties and soil organic matter content, and knowing the effect of plant roots on soil strength was carried out in the area of PT. Perkebunan Buah Subang. The research was conducted on open land, bamboo gardens, and forests with slopes of 15-30% and 30-45%. Soil strength parameters measured in the field are penetration resistance and soil shear strength. Soil physical properties and organic matter content that affect soil strength are analyzed in the laboratory. Soil strength varies with different land uses and slopes. The location of the bamboo garden with a slope of 15-30% and a slope of 30-45% shows a higher shear strength value than other locations. The shear strength of the soil at the bamboo garden location is higher because the root system has fibers that intertwine with each other to bind the soil matrix so that the soil becomes stronger to resist collapse. Soil penetration resistance is influenced by soil organic matter content, the largest amount of soil aggregate diameter (≥ 2 mm), bulk
Keyword: Distance, soil shear strength, soil penetration resistance, roots, soil physical properties

Judul: Soil Strength of Latosol and Podzolik on Various Land Use and Slope
Abstrak: Kekuatan geser tanah merupakan faktor penentu tanah dalam menopang gaya yang bekerja terhadapnya. Kekuatan geser tanah dipengaruhi salah satunya oleh vegetasi melalui kehadiran perakaran yang berperan dalam penguatan mekanik tanah dan kekuatan geser tanah. Penelitian ini bertujuan mengkaji kekuatan geser Latosol dan Podsolik pada lahan perkebunan sawit dan karet dengan kemiringan lereng berbeda serta mempelajari hubungannya dengan sifat tanah lainnya. Hasil penelitian menunjukkan bahwa kekuatan geser di Podsolik lebih tinggi dari Latosol dan pada lahan karet lebih tinggi dari lahan sawit. Kekuatan geser tanah di lereng landai pada kadar air 40% lebih kuat, sementara pada sampel tanah remolded dengan kadar air jenuh menunjukkan sebaliknya yaitu kuat geser lahan di lereng lebih curam lebih tinggi. Sifat fisik tanah C-organik, bobot isi, dan stabilitas agregat memiliki korelasi positif terhadap kekuatan geser tanah dengan nilai korelasi tertinggi pada C-organik sebesar 0,48. Latosol memiliki nilai sensitivitas yang lebih rendah dibandingkan Podsolik, yang menandakan Latosol memiliki potensi kehilangan kekuatan geser yang lebih rendah. Nilai sensitivitas tanah berkorelasi negatif dengan kandungan liat dengan tingkat korelasi tinggi yakni 0,90., Soil shear strength determines the capability of soil in supporting the pressure working on it. Soil shear strength is affected by vegetation through the presence of roots which play a role in strengthening soil mechanics and soil shear strength. This study aims to examine the soil shear strength of Latosol and Podsolik on oil palm and rubber plantations on different slopes and to study their correlation with other soil properties. The results showed that the shear strength of Podsolik was higher than Latosol and in rubber land use has a higher than in oil palm land use. The soil shear strength on gentle slope at moisture 40% water content stronger, while the remolded soil sample at a saturated water content shows the opposite, land with steeper slope has a higher. Soil physical properties soil C-organic, bulk density, and aggregate stability have a positive correlation to the soil shear strength where the highest correlation value occured on C-organic of 0.48. Latosol has a lower sensitivity value than Podsolik which indicates that Latosol has a lower potential for shear strength loss. Soil sensitivity value was negatively correlated with clay content with a high correlation level of 0.90.
Keyword: kelas lereng, sensitivitas tanah, remolded, jenis vegetasi

Judul: Pemurnian dan karakterisasi protein inhibitor RNA helikase virus hepatitis C
Abstrak: Hepatitis C virus (HCV) infection is the second most common chronic viral infection in the world with global prevalence. This infection is contribution to chronic hepatitis and liver cirrhosis, often leading to hepatocellular carcinoma. There is no effective drug and vaccine available against HCV. The current standard treatment, a combination of pegylated interferon-α with ribavirin, is limited by its suboptimal response rate in a significant patient population, side effects, and affordability. Therefore, development of effective drug is needed. One approach to find out the candidate of antiviral drug is to discover the inhibitor of enzyme that essential for virus replication, such as RNA helicase. Streptomyces chartreusis 5-095 produce the inhibitor of HCV RNA helicase. The aim of this study was to purify the protein inhibitor which has inhibition activity against ATPase activity of RNA helicase HCV from S. chartreusis 5-095. The supernatant of culture S. chartreusis 5-095 exhibited high inhibiton activity against ATPase activity of RNA helicase HCV (approximately 72%) at 10 days of incubation. The extracellular protein inhibitor was partially purified by procedures of precipitation with ammonium sulfate to 65% saturation and gel filtration (Sephadex G50) using methanol water solution (4:6) as an eluen. The purity of protein inhibitor was monitored by SDS PAGE. The protein inhibitor showed a relative molecular mass were estimated to be 14 kDa and increased the purity 23,08 fold than those of the crude protein. The specific activity and IC50 after purification were 13,1338 U/mg and 0,0767 mg/mL, respectively. The activity of purified protein inhibitor showed its stability over pH range from 5-8 and optimum at pH 7,4. The inhibition activity showed its stability up to 70% at temperature 100 oC. The purified protein inhibitor relatively stable its activity at storage in the range of -20 oC to room temperature for 35 days.
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