Judul: Degradation Of Calcium Oxcalate In Porang Flour Employing Microbubble Cavitation
Abstrak: Porang flour contains a fairly high calcium oxalate (CO) in which consuming it directly can cause kidney stone disease in humans. The aim of this study was to obtain the optimal operating parameters of the CO degradation process in porang flour using a swirling-flow nozzle hydrodynamic cavitation technique. This study consists of 3 stages; stage 1 determining the particle size, concentration of NaCl solution and ratio (porang flour: NaCl solution: isopropyl alcohol) to the level of viscosity for the cavitation process; the 2 nd stage, determining the limit values on the air flow rate, fluid, and cavitation time to optimize the CO degradation; 3 rd stage, CO degradation process with variable operation on hydrodynamic cavitation technique by swirling-flow nozzle type. The hydrodynamic cavitation tool used in this study had a 7 mm nozzle orifice in a vertical position. The nozzle used is made of Plexiglas with an outer diameter of 80 mm and a height of 160 mm which consists of a vortex chamber and air holes. The fluid flow in this tool is regulated by a centrifugal pump type. The optimization process was carried out using the response surface method of the box-behnken model in design expert 13.0 software with 17 formulations and 3 verification processes for optimal operating parameters. The finest solution formulation could pass through the nozzle and formed microbubbles with a viscosity level of >10 cP on 40 mesh particles, 5% NaCl concentration, and ratio (porang flour: NaCl: isopropyl alcohol) 1:20:20 (w/v). The limit values for the optimization process were in the range Qg = 0.5-1.5 lpm, Ql = 8-12 lpm, and cavitation time of 15-25 minutes. The preeminent CO degradation process was obtained at Ql/Qg = 10/1 lpm ratio with a cavitation time of 20 minutes. This process produced 29.7 mg/100g CO content with a degradation percentage of 85.53%. The produced calcium oxalate indicates that it meets the required standard tolerance limit for the human body which is 71 mg/100g, and below SNI 7938:2020 which is a maximum of 30 mg/100g. In other words, porang flour produced from this process is safe for consumption.
Keyword: Porang Flour, Calcium Oxcalate, Microbubble, Optimization, Response Surface Method

Judul: Effect of acetic acid and table salt solution on reduction of calcium oxalate in porang banten flour (Amorphophallus muelleri)
Abstrak: Menurunnya harga umbi porang memberikan dampak perekonomian bagi petani. Petani pada umumnya hanya mengolah umbi porang menjadi chips porang maupun tepung porang dengan kadar kalsium oksalat tinggi. Konsumsi kalsium oksalat dalam jumlah tinggi mengakibatkan gatal di tenggorokan, rasa panas di mulut, serta menyebabkan batu ginjal. Penurunan kadar kalsium oksalat dapat dilakukan dengan perendaman larutan garam dapur maupun asam asetat. Penelitian ini bertujuan mempelajari pengaruh jenis larutan, teknik perendaman, serta lama perendaman terhadap kadar kalsium oksalat dan karakteristik tepung porang. Perlakuan yang diberikan pada chips porang basah berupa perendaman dalam CH3COOH 20% dan NaCl 15%. Teknik selama perendaman adalah pengadukan dan tanpa pengadukan, masing-masing selama 60, 90, dan 120 menit. Penelitian dilakukan dalam dua tahap yaitu pembuatan tepung porang serta karakterisasi fisikokimia yang terdiri dari analisis kadar air, kadar abu, kadar glukomanan, kadar kalsium oksalat, dan nilai derajat putih. Hasil penelitian menunjukkan bahwa perlakuan pengadukan dan semakin lama perendaman mampu menurunkan kadar kalsium oksalat. Hasil penelitian terbaik diperoleh dari perendaman NaCl dengan pengadukan selama 120 menit. Perlakuan tersebut menghasilkan kadar kalsium oksalat 69,59 mg/100 g dengan persentase penurunannya sebesar 92,24% dibandingkan kontrol. Hasil karakteristik lain yang diperoleh yaitu kadar air 9,88%, kadar abu 9,23%, kadar glukomanan 43,11%, dan derajat putih 50,65%., The decline in the price of porang tubers has an economic impact on farmers. Farmers generally only process porang tubers into porang chips and porang flour with high levels of calcium oxalate. Consumption of high amounts of calcium oxalate causes itching in the throat, burning sensation in the mouth, and causes kidney stones. The decrease in calcium oxalate levels can be done by soaking in a solution of table salt or acetic acid. This study aims to study the effect of the type of solution, immersion technique, and duration of immersion on calcium oxalate levels and characteristics of porang flour. The treatment given to wet porang chips was immersion in 20% CH3COOH and 15% NaCl. The technique during immersion was stirring and without stirring, for 60, 90, and 120 minutes, respectively. The research was conducted in two stages, namely the manufacture of porang flour and physicochemical characterization consisting of analysis of moisture content, ash content, glucomannan content, calcium oxalate content, and whiteness value. The results showed that the stirring treatment and the longer soaking were able to reduce calcium oxalate levels. The best research results were obtained from soaking NaCl with stirring for 120 minutes. This treatment resulted in calcium oxalate levels of 69.59 mg/100 g with a percentage decrease of 92.24% compared to controls. Other characteristic results obtained are 9.88% moisture content, 9.23% ash content, 43.11% glucomannan content, and 50.65% whiteness.
Keyword: acetic acid, calcium oxalate, glucomannan, porang flour, salt

Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
Keyword: