Judul: Rekayasa Proses Pembuatan Pewarna Bubuk Alami dari Biji Pinang (Areca catechu L.) dan Aplikasinya untuk Industri
Abstrak: Natural dyes have become alternative of non toxic, environtmentally friendly colorants, usually agro-renewable source and exhibit better biodegradability. Instant natural dyes, e.g. powder extracts, are still limited. Areca catechu L. is one of dye plant that has been traditionally used on batik and craft dyeing. The phenolic substances, as coloring matter, from areca seeds are varying in degree of maturation. For these reasons, design process of natural dye powder production from areca seeds by spray drying and its application in textile dyeing and transparent soap coloring was studied. The objective of this study was to determine the effect of maturation degree of areca seeds (unripe, ripe) and binder treatment (without a binder, arabic gum 2% w/v) to the characteristics of areca seeds powder extracts, and determine the effect of areca seeds dye powder and fixative agents (without a fixative agent, alum, calcium oxide and ferrosulfate) to the colour of two types of fabric (cotton, silk) and the color changes to washing and sun drying. The objective of study about application of areca seeds powder extracts in transparent soap was to determine the effect of areca seeds extracted powders and the type of vegetable oil to the characteristics of transparent soap. Areca seeds powder extracts being used in this study were areca seed powder extracts without a binder and areca seed extracted powder with a binder (arabic gum 2% w/w). Two types of vegetable oil for making transparent soap were used in this study namely coconut oil and mixed of coconut oil and palm oil (15:5 w/w). As a control, there were transparent soaps made without addition of areca seeds powders. The results of this study exhibited unripe areca seeds produced powder extracts with higher in yield, moisture content and total phenolic content but had no significant effect on pH and lower in bulk density and solubility than ripe areca seeds. Arabic gum treatment produced powder extracts with higher in yield, and solubility, but had no significant effect on moisture content and lower in bulk density, pH and total phenolic content than the treatment without binder. The areca seeds powder extracts had the yield ranges between 5,59-13,90%, moisture content ranges between 5,19% - 7,41%, bulk density ranges between 0,3720 – 0,5586 g/ml, solubility (on water) ranges between 94,10% – 99,25%, pH ranges between 4,98 – 5,31, total phenolic content ranges between 30,50 – 67,07% and oHue ranges between 39,67 – 62,06 (red and yellow red). FTIR spectrum showed presence of functional group of OH, CH, CO and aromatic structure in areca seeds dye powder. The areca seed powder extracts exhibited cytotoxic activity against brine shrimp larvae with LC50 values ranging from 279,53-1093,25 ppm. The fixative agents had significant effects on colour of cotton and silk fabric. Alum caused the depth of fabric colour as same as or lower than colored fabric without a fixative agent (color ranges in red and yellow red). The highest viii depth of fabric colour is given by ferrosulfate was followed by calcium oxide. Calcium oxide give the little color changes on both cotton and silk fabric in washing
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Judul: Rekayasa Proses Ekstraksi dan Pembuatan Pewarna Bubuk Alami dari Mahoni (Swietenia mahagoni) dan Aplikasinya untuk Pewarnaan Tekstil
Abstrak: The use of natural dyes in textile dyeing is the best option to avoid the negative impact of the carcinogenic potential contamination from synthetic dyes. Swietenia mahagoni is one of dye plant that have chemical coumpound as natural dye, such as flavonoid and tannin. Unfortunately, natural dye in Indonesia has not been widely available in the form of ready-made, such as powder form so can not be stored for a long time, the color is less stable and the process takes a long time so it is less practical in its use. The aim of this study was to extract natural dyes from wood and bark of mahagony based on optimum conditions of extraction process, determine the effect of binder treatment to the characteristics of mahagony extract colouring powder using spray dryer, and application of the natural dye in textile dyeing. The scope of this study includes the characteristics of wood and bark of mahagony, determination of appropriate type of solution (water, ethanol, metanol, ethyl acetate), determination of concentration of solution to dissolve the dye contained in the mahagony, determination of effect of binder treatment (without binder, dextrin 2% w/v, arabic gum 2% w/v) to characteristics of mahagony extracted powder, and application of natural dye powder to cotton and silk fabric with different fixative agents (without a fixative agent, alum, calcium oxide and ferrosulfate) to determine their effects on the colour of fabrics and the colour fastness to washing and sun drying treatment. The results showed that bark of mahagony and metanol solvent with concentration of 50% gave the best result on total yield and tannin content. Binder treatment had significant effect on the yield, moisture content, bulk dencity, water solubility, alcohol solubility, and colour stability. The mahagony extracted powders had the yield ranges between 3.38 – 10.36%, moisture content ranges between 6.57-7.23%, bulk density ranges between 0.051– 0.118 g/ml, solubility on water ranges between 77.56 – 81.22%, solubility on alcohol ranges between 57.26 – 92.01%, oHue ranges between 50.30 – 52.83 (red) and the best stability was found on the treatment with arabic gum binder. The fixative agents had significant effects on colour of cotton and silk fabric. Calcium oxide gave the highest colour fastness in silk fabric, while alum gave the highest result on colour fastness in cotton fabric toward washing treatment.
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Judul: Solusi Geometri Schwarzschild untuk Dimensi 4+1 dengan Invarian Rotasi Isotropik
Abstrak: Metrik Schwarzschild merupakan solusi eksak pertama dari persamaan medan Einstein dengan mangasumsikan metrik statik dan simetris. Metrik Schwarzschild yang ditemukan oleh Karl Schwarzschild masih dalam dimensi 3+1, namun seiring dengan teori-teori terbaru yang menunjukkan bahwa alam semesta tidak hanya di dimensi 3+1. Maka melalui penambahan dimensi, tujuan penelitian ini memperoleh solusi pada geometri Schwarzschild untuk dimensi 4+1 dengan memodifikasi koordinat bola yang invarian rotasi isotropik dan melalui penurunan rumus seperti koordinat bola, simbol Christoffel, dan tensor Ricci. Selain mendapatkan solusi ini, metrik Schwarzschild dimensi 4+1 dapat digunakan sebagai metrik dasar untuk memperoleh solusi blackhole dan wormhole pada dimensi 4+1. Hasil akhirnya, dengan memanfaatkan modifikasi koordinat bola, metrik Schwarzschild dapat dibentuk sehingga diperoleh solusi geometri Schwarzschild untuk dimensi 4+1.
Keyword: metrik Schwarzschild, persamaan medan Einstein, modifikasi koordinat bola, penambahan dimensi, invarian rotasi isotropik