Studies on fabrication, morphology and performances of bi-layer electrospun nanofibre membranes

The current study investigated the fabrication and characterization of homogeneous and heterogeneous bi-layer membranes using electrospinning technique. The membranes were fabricated from four polymers: hydrophilic polymers such as polyamide 6 (Nylon 6) and polyvinyl Alcohol (PVA) and hydrophobic polymers such as polyacrylonitrile (PAN) and copolymer poly(vinylidene fluoride)-Hexafluoropropylene (copolymer PVDF)) polymers. A preliminary study was carried out to determine the optimal conditions of electrospinning for each of the above polymers. The optimal conditions for each polymer were different and were determined based upon uniform cylindrical fibres, large coverage area and uniform membrane structures. The study demonstrated that the resultant average fibre diameters for electrospun Nylon 6, PVA, PAN and copolymer PVDF were 109 + 16, 259 + 39, 677 + 205 and 570 + 105 nm, respectively. From the FTIR analysis, the electrospinning was found to transform crystal phases of polymers such as Nylon 6 and PVDF. Changes in the crystal phases were confirmed by the wide angle X-ray diffraction (WAXD) diffraction peaks. The optimal conditions for each polymer were then used to fabricate bi-layer membranes. The bi-layer membranes were fabricated as: homogeneous bi-layer membranes (membrane composed of two identical polymers) and heterogeneous bi-layers membranes (membrane composed of two different polymers, hydrophobic and hydrophilic). The bi-layer membranes were characterized for membrane thickness and surface wettabilities. The membranes were also tested for tensile properties and adhesion strength. The tensile properties for homogeneous bi-layer could be affected by the membranes pore sizes and bonding between fibres in the membrane. For heterogeneous bi-layer membranes, the tensile properties were different depending on the combination of polymers used. For adhesion strength, bi-layer PVA/PVA showed far higher adhesion highest adhesion strength at about 78 mN/mm2 compared to others. For other membranes, the adhesion strengths were lower than 7 mN/mm2. In addition, a modified 180° peel test was developed to evaluate adhesion strengths between the top and bottom layers of the bi-layer membranes. A support system (glass slide) was introduced in order to prevent unnecessarily movement of the sample during the test. The application of homogenous and heterogeneous bi-layer electrospun membranes for the removal of contaminants in textile effluent was investigated. The fine pore sizes of homogenous bi-layer Nylon 6/Nylon 6 exhibited the best performance with the highest effluent removal of 99%. The large pore sizes of commercial membrane gave a much lower performance of improving 33 to 35% of the effluent turbidity. Poor quality of permeate was also observed for the large pore sizes of homogenous bi-layer PAN/PAN and homogenous copolymer PVDF/PVDF membranes. However, the accumulation of suspended solid particles over the homogenous bi-layer Nylon 6/Nylon 6 surface exhibited the lowest flux for the membrane as compared to the commercial membrane and homogeneous bi-layer membranes. For heterogeneous bi-layer membranes, the membranes were found to give a lower flux due to the presence of electrospun Nylon 6. However, the presence of electrospun Nylon 6 in the membranes was found to give an excellent removal of suspended solids from liquid

Pengaruh Pemupukan Urea Dan Teknik Defoliasi Pada Produksi Jagung (Zea Mays L.) Varietas Pioneer 27

Penelitian mengenai “Pengaruh Pemupukan Urea dan Teknik Defoliasi Pada Produksi Jagung (Zea mays L.) Varietas Pioneer27” telah dilaksanakan di Kebun Percobaan Politeknik Negeri Lampung dari bulan November 2011 sampai bulan Februari 2012. Tujuan penelitian adalah untuk mengetahui dosis pupuk urea yang optimum terhadap produksi tanaman jagung varietas pioneer 27, mengetahui produksi tanaman jagung varietas pioneer 27 dengan perlakuan defoliasi atau tanpa defoliasi, dan mengetahui interaksi antara dosis pupuk Urea dan defoliasi pada tanaman jagung varietas pioneer 27. Perlakuan disusun secara faktorial (4 x 2) dengan ulangan sebanyak 3 (tiga). Faktor pertama adalah pupuk urea yang terdiri dari 4 (empat) taraf yaitu 100 kg ha-1 (P1), 200 kg ha-1 (P2), 300 kg ha-1 (P3) dan 400 kg ha-1 (P4). Faktor kedua adalah teknik defoliasi yang terdiri dari 2 (dua) taraf yaitu tanpa defoliasi (D0) dan defoliasi disisakan tiga daun dibawah tongkol (D1). Homogenitas ragam antar perlakuan diuji dengan uji Barlett dan kemenambahan data diuji dengan uji Tukey. Selanjutnya data dianalisis ragam dan dilanjutkan dengan uji lanjutan polinomial ortogonal 5%. Hasil penelitian menunjukkan bahwa pemberian dosis sebesar 100 kg ha-1 ureamampu memberikan bobot biji kering per petak sebesar 11,61 kg yang setara dengan 9,5 t ha-1, dan pemberian > 200 kg ha-1 tidak nyata meningkatkan bobot biji per petak. Perlakuan defoliasi ataupun tanpa defoliasi tidak bebeda terhadap bobot biji kering tanaman jagung. Terdapat interaksi antara dosis pupuk urea dengan perlakuan defoliasi untuk meningkatkan bobot berangkasan yaitu dengan dosis pupuk 254,77 kg ha-1 urea dengan teknik defoliasi akan menghasilkan bobot kering brangkasan yang optimum sebesar 113,87 g

Anatomialat Pencernaan Ikan Buntal Pisang (Tetraodon Lunaris) [Anatomy of the Digestive Apparatus of the Puffer Fish Tetraodon Lunaris]

This research was aimed to study not only on gross morphologically but also on the histological structure of the Tetraodon lunaris digestive apparatus. The fish samples were obtained from a fisherman at the fish auction in Pelabuhan Ratu, from August 2005 until March 2006. The ratio between intestine and length/body length represented that this fish is carnivorous. The esophagus is short and the gastric forms a simple pouch with two of small diverticula. The intestine consists of a single loop. The esophagus and gastric mucous layer is covered with epithelial stratified cells. The intestine mucous layer has covered with a layer of columnar epithelial cells. The esophagus and gastric muscular layer consist of striated muscle. The sphincter pylorica and the intestine muscular layer consist of smooth muscle. The anus mucous layer consits of epithelial cuboid and it has the muscular layer of striated muscles. The liver has oval-shaped greenish vesica fellea with ductus choledochus emptied at the anterior part of intestine. The hepatocyt cells have a polygonal shape with lipid droplets in its. The exocrine glands of the pancreas tissue showed a set of acinar cells in the liver parencyhm, around portal vein, hepatic artery and biliary ductules