445 research outputs found

    ANALISIS KETERBUKAAN TANAH HUTAN AKIBAT KEGIATAN PEMBUKAAN WILAYAH HUTAN DI HUTAN ALAM PRODUKSI

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    Terjadinya keterbukaan tanah hutan dalam kegiatan pengelolaan hutan, salah satunya disebabkan kegiatan pembukaan wilayah hutan, seperti: pembuatan jaringan jalan hutan (jalan utama, jalan cabang, jalan sarad), TPn, TPK, base camp dan lain sebagainya. Penelitian ini bertujuan  (a) menghitung kerapatan jaringan jalan hutan, meliputi: jalan utama, jalan cabang dan jalan sarad; (b) menghitung persen keterbukaan tanah hutan akibat kegiatan pembukaan wilayah hutan (pembuatan jalan utama, jalan cabang, jalan sarad dan TPn. Lokasi penelitian di IUPHHK-HA PT Bumimas Abadi Kalimantan Tengah. Hasil penelitian menunjukkan bahwa kerapatan jaringan jalan hutan berkisar 3,54 – 36,48 m/ha. Persen keterbukaan tanah hutan akibat kegiatan pembukaan wilayah hutan (pembuatan jalan utama, jalan cabang, jalan sarad dan TPn) berkisar 0,42 – 10,21%. Jalan sarad memiliki kerapatan jaringan jalan hutan dan persen keterbukaan tanah hutan yang paling tinggi dibandingkan dengan jalan utama dan jalan cabang

    Pengaruh Kecepatan Rotor dan Konsentrasi Katalis pada Pembuatan Biodiesel dari Cpo dengan Reaksi Esterifikasi Menggunakan Sentrifugal Kontaktor

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    Fuel needed for diesel engines in Indonesia each year increased along with the number of industrial machinery and the amount of diesel vehicles engine. With limited oil reserves, it is necessary to look for alternative sources of energy. Centrifugal contactor technology is one of the alternative technology of biodiesel production is very likely to be developed. Therfore, we need a study of biodiesel production using palm oil feedstock and methanol as reagent and sulfuric acid as a catalyst by using the esterification reaction. And this study used centrifugal contractors as the main equipment, which is equipped with a heater, raw material tank, product tank and pumps. Fixed variables selected in this study is the reaction time of 120 minutes, the molar ratio of feed is 9:1, and 60 ° C operating temperature. While the manipulated variable is rotor speed (1200, 1800 and 2400 rpm), the concentration of sulfuric acid catalyst (5%, 10% and 15% v/v methanol). The results of the research that has been done is the characteristics of biodiesel produced in this study, the kinematic viscosity values from 2,41 to 2,51 mm2/s, density 858-863 kg/m3, and acid number 6,30 to 6,66 mg-KOH/g. The composition of the methyl ester obtained is 0,33% behenic metyl ester, 48,87% palmitic methyl ester and 50,80% oleic methyl ester. The best conversion is 56,03% at the optimum operating conditions with a catalyst concentration of sulfuric acid 10% v/v methanol and the rotor speed of 2400 rpm. Correlation of rotor speed on reaction rate constant is k = 0,0002Re(0,1928) . And the relationship of the catalyst concentration the reaction rate constant is k = 0,0055[Q] 0,089

    Saran Aksi Saham Dengan Pendekatan Fundamental Dan Teknikal Menggunakan Metode Learning Vector Quantization Neural Network

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    Stock is one instrument that is traded in the capital market. Investment in the form of shares can also offer enormous profit, even though it is highly risky in the investment especially on weekly stock trade.; Based on this reason, a system is developed to help take action in transactions whether to buy, sell or hold the stock. This analysis system uses technical and fundamental approach by applying Learning Vector Quantization (LVQ). This research uses five inputs taken from technical analysis, namely: Open Price, High Price, Low Price, Close Price, and Volume. One more input from the fundamental approach is Last Price. This system test indicated 72% accuracy on the transaction actions

    Disrupting Circadian Homeostasis of Sympathetic Signaling Promotes Tumor Development in Mice

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    and why disruption of circadian rhythm may lead to tumorigenesis. oncogenic potential, leading to tumor development in the same organ systems in wild-type and circadian gene-mutant mice. is a clock-controlled physiological function. The central circadian clock paces extracellular mitogenic signals that drive peripheral clock-controlled expression of key cell cycle and tumor suppressor genes to generate a circadian rhythm in cell proliferation. Frequent disruption of circadian rhythm is an important tumor promoting factor

    Induction of sodium iodide symporter gene and molecular characterisation of HNF3β/FoxA2, TTF-1 and C/EBPβ in thyroid carcinoma cells

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    Thyroid carcinoma cells often do not express thyroid-specific genes including sodium iodide symporter (NIS), thyroperoxidase (TPO), thyroglobulin (TG), and thyrotropin-stimulating hormone receptor (TSHR). Treatment of thyroid carcinoma cells (four papillary and two anaplastic cell lines) with histone deacetylase inhibitors (SAHA or VPA) modestly induced the expression of the NIS gene. The promoter regions of the thyroid-specific genes contained binding sites for hepatocyte nuclear factor 3 β (HNF3β)/forkhead box A2 (FoxA2), thyroid transcription factor 1 (TTF-1), and CCAAT/enhancer binding protein β (C/EBPβ). Quantitative reverse transcription-polymerase chain reaction (RT–PCR) showed decreased expression of HNF3β/FoxA2 and TTF-1 mRNA in papillary thyroid carcinoma cell lines, when compared with normal thyroid cells. Forced expression of these genes in papillary thyroid carcinoma cells inhibited their growth. Furthermore, the CpG island in the promoter region of HNF3β/FoxA2 was aberrantly methylated; and treatment with 5-aza-2-deoxycytidine (5-Az) induced its expression. Immunohistochemical staining showed that C/EBPβ was localised in the nucleus in normal thyroid cells but was detected in the cytoplasm in papillary thyroid carcinoma cells. Subcellular fractionation of papillary thyroid carcinoma cell lines also demonstrated high levels of expression of C/EBPβ in the cytoplasm, suggesting that a large proportion of C/EBPβ protein is inappropriately localised in the cytoplasm. In summary, these findings reveal novel abnormalities in thyroid carcinoma cell

    Minimum Criteria for DNA Damage-Induced Phase Advances in Circadian Rhythms

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    Robust oscillatory behaviors are common features of circadian and cell cycle rhythms. These cyclic processes, however, behave distinctively in terms of their periods and phases in response to external influences such as light, temperature, nutrients, etc. Nevertheless, several links have been found between these two oscillators. Cell division cycles gated by the circadian clock have been observed since the late 1950s. On the other hand, ionizing radiation (IR) treatments cause cells to undergo a DNA damage response, which leads to phase shifts (mostly advances) in circadian rhythms. Circadian gating of the cell cycle can be attributed to the cell cycle inhibitor kinase Wee1 (which is regulated by the heterodimeric circadian clock transcription factor, BMAL1/CLK), and possibly in conjunction with other cell cycle components that are known to be regulated by the circadian clock (i.e., c-Myc and cyclin D1). It has also been shown that DNA damage-induced activation of the cell cycle regulator, Chk2, leads to phosphorylation and destruction of a circadian clock component (i.e., PER1 in Mus or FRQ in Neurospora crassa). However, the molecular mechanism underlying how DNA damage causes predominantly phase advances in the circadian clock remains unknown. In order to address this question, we employ mathematical modeling to simulate different phase response curves (PRCs) from either dexamethasone (Dex) or IR treatment experiments. Dex is known to synchronize circadian rhythms in cell culture and may generate both phase advances and delays. We observe unique phase responses with minimum delays of the circadian clock upon DNA damage when two criteria are met: (1) existence of an autocatalytic positive feedback mechanism in addition to the time-delayed negative feedback loop in the clock system and (2) Chk2-dependent phosphorylation and degradation of PERs that are not bound to BMAL1/CLK

    Efficient preparation of Arabidopsis pollen tubes for ultrastructural analysis using chemical and cryo-fixation

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    The pollen tube (PT) serves as a model system for investigating plant cell growth and morphogenesis. Ultrastructural studies are indispensable to complement data from physiological and genetic analyses, yet an effective method is lacking for PTs of the model plant Arabidopsis thaliana. Methods: Here, we present reliable approaches for ultrastructural studies of Arabidopsis PTs, as well as an efficient technique for immunogold detection of cell wall epitopes. Using different fixation and embedding strategies, we show the amount of PT ultrastructural details that can be obtained by the different methods. Results: Dozens of cross-sections can be obtained simultaneously by the approach, which facilitates and shortens the time for evaluation. In addition to in vitro-grown PTs, our study follows the route of PTs from germination, growth along the pistil, to the penetration of the dense stylar tissue, which requires considerable mechanical forces. To this end, PTs have different strategies from growing between cells but also between the protoplast and the cell wall and even within each other, where they share a partly common cell wall. The separation of PT cell walls in an outer and an inner layer reported for many plant species is less clear in Arabidopsis PTs, where these cell wall substructures are connected by a distinct transition zone. Conclusions: The major advancement of this method is the effective production of a large number of longitudinal and cross-sections that permits obtaining a detailed and representative picture of pollen tube structures in an unprecedented way. This is particularly important when comparing PTs of wild type and mutants to identify even subtle alterations in cytoarchitecture. Arabidopsis is an excellent plant for genetic manipulation, yet the PTs, several-times smaller compared to tobacco or lily, represent a technical challenge. This study reveals a method to overcome this problem and make Arabidopsis PTs more amenable to a combination of genetic and ultrastructural analyses
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