Kinetika Release Mikrokapsul Oleoresin Jahe Merah Dalam Medium Stimulated Intestinal Fluid (SIF): Pengaruh Konsentrasi Kitosan dan Volume Cross-linker

Kinetika release bertujuan untuk menyediakan dosis untuk pencapaian konsentrasi obat yang sesuai. Tujuan penelitian ini adalah menentukan kinetika release mikrokapsul oleoresin jahe berdasarkan perubahan konsentrasi kitosan dan volume agen crosslink dan menentukan koefisien difusi oleoresin jahe merah melalui dinding mikrokapsul. mikrokapsul oleoresin jahe merah dipreparasi dari campuran oleoresin jahe merah dalam larutan kitosan dan diaduk untuk membentuk emulsi. seteleh itu ditambahkan ke minyak jagung dan diaduk kembali untuk membentuk emulsi kedua. Glutaraldehyde saturated toluene diteteskan sedikit demi sedikit setelah selesai ditambahkan 25% larutan glutaraldehida dan tetap diaduk selama 2 jam. mikrokapsul oleoresin jahe merah dipisahkan dan dicuci dengan petroleoum eter dan heksan, kemudian dikeringkan dalam oven. Mikrokapsul di masukkan dalam medium release yaitu simulated intestinal fluid tanpa enzim kemudian sampel dianalisis menggunakan spektrofotometer UV-vis untuk mengetahui absorbansinya. Nilai koefisien relasi (R2) tertinggi didapat dari model kinetika release Korsmeyer-Peppas yaitu R2 = 0.73-0.85 dengan nilai n = 0.39-0.41. Berdasarkan nilai n tersebut mekanisme release dari mikrokapsul oleoresin jahe merah adalah secara Fickian. Koefisien difusi yang dihasilkan yaitu 2.807 x 10-13- 3.675 x 10-13 cm2/detik

Actin During Pollen Germination

The cytoplasm of the vegetative cell of the ungerminated pollen grain of Endymton non-scriplus and other angiosperm species contains numerous fusiform bodies sometimes exceeding 15μm in length and 2.5 μm in width, which bind fluorescent-labelled phalloidin and are likely therefore to constitute a storage form of actin. The bodies are dispersed during the activation of the pollen, being replaced by aggregates of slender phalloidin-binding fibrils, which converge towards the germination apertures and are present in the emerging pollen tube. The storage bodies appear to be homologous with crystalline-fibrillar structures, shown in an earlier paper to be abundantly present in the vegetative cells of Nicotiana pollen. These are composed of massive aggregates of linearly disposed units with individual widths of 4–7 nm, probably to be interpreted as actin microfilaments. Vegetative-cell protoplasts from mature but ungerminated pollen disrupted in osmotically balancing medium release extended phalloidin-binding fibrils of a kind not observed in the intact grain. It is suggested that these are derived by the rapid dissociation of the compact actin storage bodies present in the vegetative cell at this stage of development.

CELL SURFACE IMMUNOGLOBULIN

Turnover and release of cell surface Ig and secretion of total intracellular Ig has been studied in small lymphocytes from normal mouse spleen. The major findings to emerge are: (a) small lymphocytes secrete 8S IgM and IgG. A small portion of the 8S IgM, but virtually none of the IgG appears to have a cell surface phase. (b) Cell surface IgM is actively turned over with a half-life of 6–8 hr, and turnover can be accounted for by release into the incubation medium. Release is temperature dependent. (c) Released cell surface Ig is noncovalently bound to a fragment of plasma membrane. (d) H-2 antigens are not released during short-term incubation. Based on the above findings, we propose a model for the transport and release of both cell surface and conventionally secreted Ig.

Sources of nitrogen and methods of application for flooded rice: I. Comparison of two methods of applying slow release and standard fertilizer materials

Field experiments with rice were conducted on a flooded soil comparing two standard fertilizers with N fertilizers with various release rates. For each of these fertilizer materials two methods of application were compared: broadcast and incorporated, and placement at 15 cm depth. The .slow release materials resulted in a lower grain yield than did fast or medium release rate or standard fertilizer materials. They released N too slowly during the early growth of rice to permit optimum plant growth and development.Placement of 80 kg/ha N at 15 cm depth increased the plant N content at all stages of growth and significantly increased the grain yield compared with the broadcast-and-incorporated fertilizer treatment. The highest grain yield in the experiment (7701 kg/ha rough rice) was obtained from a medium release material, which was 88 % more efficient in increasing grain yield per unit of N when placed at 15 cm than when broadcast-and-incorporated.The recovery of fertilizer N was 68% when deeply placed and 38 % when broadcast-andincorporated.