Judul: The Determinant Formulation of Circulant Matrix with entry of the 2nd Order Recurrence Relation Number Formasi Jangkar
Abstrak: Matriks circulant merupakan matriks segi yang entri-entri pada setiap barisnya sama dengan entri-entri pada baris sebelumnya dan bergeser posisi ke kanan. Entri-entri dari matriks circulant dapat diisi dengan berbagai entri, salah satunya adalah bilangan-bilangan yang membentuk suatu barisan bilangan. Barisan bilangan dapat dibuat dengan menggunakan relasi rekurensi orde-2. Pada karya ilmiah ini, relasi rekurensi tersebut didefinisikan sebagai \[J_{n}=2J_{n−1}+3J_{n−2}\] dengan syarat awal \[J_0=3,J_1=1,n≥2,\] dan membentuk barisan bilangan yang dinamakan Formasi Jangkar. Kemudian, determinan matriks circulant dengan entri barisan bilangan Formasi Jangkar dapat dirumuskan secara eksplisit menggunakan sifat-sifat determinan sederhana yang berkaitan dengan operasi baris dasar., The circulant matrix is a faceted matrix where the entries in each row are the same as the entries in the previous row and shift position to the right. The entries of the circulant matrix can be filled with various entries, one of which is the numbers that form a sequence of numbers. Sequences of numbers can be constructed by a recurrence relation of order-2. In this scientific work, the recurrence relation is defined as \[J_{n}=2J_{n−1}+3J_{n−2}\] with initial condition \[J_0=3,J_1=1,n≥2,\] and form a sequence of numbers called Formasi Jangkar. Then, the determinant of the circulant matrix with entry the Formasi Jangkar can be formulated eksplicitly using the properties of determinants based on elementary row operations.
Keyword: bilangan Formasi Jangkar, determinan, matriks circulant, operasi baris  dasar, Relasi rekurensi, circulant matrix, elementary row operation, Formasi  Jangkar number, recurrence relation, determinant

Judul: Determinan dan Invers Matriks Circulant dengan Entri Barisan Aritmetika
Abstrak: Matriks circulant adalah matriks segi yang entrinya bergeser satu kolom ke kanan secara berurutan. Sehingga entri matriks circulant dapat dilihat dari satu kolom atau satu baris matriks tersebut. Salah satu sifat yang dimiliki matriks circulant, adalah bahwa inversnya juga bersifat circulant. Entri baris pertama suatu matriks circulant dapat diisi dengan berbagai bentuk barisan bilangan yang salah satunya adalah barisan aritmetika. Pada karya ilmiah ini diformulasikan secara eksplisit determinan dan invers matriks ... dst, Circulant matrix is a square matrix whose entry are shifted one column to the right sequentially. So the entry of a circulant matrix can be seen as one column or one row of the matrix. One of the property of a circulant matrix is the inverse also in the form of circulant. The first row of a circulant matrix can be filled in various type of sequence of numbers such as arithmetic sequence. In this research, the determinant and the inverse of a circulant matrix ... dst
Keyword: arithmetic sequence, circulant matrix, determinant, inverse

Judul: Antioxidant activity of Pluchea indica Less leaves methanolic extract and its fraction and their capacity to inhibit cooked duck meat warmed over flavor
Abstrak: Pluchea indica Less is a herb commonly used as food and traditional medicine. Its leaves have antioxidant activity due to its various phytochemical compounds. The antioxidant activity of methanolic extract of Pluchea leaves to prevent cooked duck meat warmed over flavor (WOF) is still under explored. The objective of this study was to investigate the antioxidant activity of methanolic extract of Pluchea leaves and its fraction (ethyl acetate, water, and n-butanol) by using different analysis approaches test systems (2,2-phenyl-1-picrylhydrazyl (DPPH), superoxide and hydroxyl radical-scavenging activities, hydrogen peroxide scavenging activity, ferric reducing power, iron chelating capacity, and -carotene-linoleic acid bleaching assay). Furthermore, their application as inhibitor to cooked duck meat WOF has also been conducted. Antioxidant activity of Pluchea leaves was obtained by dividing its leaves into 3 groups, i.e 1-3, 4-6 and >6. The methanolic extract of those groups contained phytochemical compounds, such as tannin, sterol, phenol hydroquinone, and flavonoid. The methanolic extract of 1-6 Pluchea leaves (EMB) had more potential source of DPPH free radical scavenging activity. In addition, this extract was fractionated by various solvents with different polarity, such as ethyl acetate, n-butanol, and water. The result showed that ethyl acetate fraction (FEA) had higher antioxidant activity than EMB and the other fraction, but its activity was lower than methanolic extract of green tea (EMT). The antioxidant activity assay of EMB and FEA was compared to BHT and -tocopherol by using different analysis approaches test systems. It showed that FEA had superoxide radical-scavenging activity, iron chelating capacity and ferric reducing power, while EMB had superoxide radical-scavenging activity, ferric reducing power and -carotene–linoleic acid bleaching assay. FEA at 250 ppm concentration was more effective to prevent the formation of cooked duck meat WOF than FEA at 600 ppm concentration and EMB. This fraction significantly inhibited the oxidation of PUFA (linoleic and arachidonic acids) and the formation of malondialdehide (MDA) and hexanal content. In comparison with FEA, EMB showed less potent antioxidant activity. However, the volatile compounds in EMB extract had an effect in improving sensory properties of duck meat, mainly by increased hedonic-preference scores on acceptance sensory test and also suppressed green and grassy aromatic intensities of duck meat during cooking and storage.
Keyword: Asteraceae