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## Stabilisasi Lumpur Kering Dari Limbah Cair Pengolahan Kulit Dengan Abu Layang

ABSTRACT: The experiment of solidification of dry sludge of liquid waste of leather treatment are containing chrome (Cr) by using fly ash has been done.  The experiment objective are immobilize Cr in the solid waste by using pozzoland cement was made of fly ash in order to stable in the repository.  The experiment were carried out by solidification of solid waste are containing total chrome of 1480.5 mg/kg sum of 2 – 10 weight % of (water + pozzoland cement) by using pozzoland cement was made from the mixture of fly ash and calcite were burned at 1000oC temperature for 2 hours.  The characterization of the solid composite of stabilization result consist of the  compressive strength test and the leaching test by American Nuclear Society (ANS-16.1) method.  The experiment result were shown that pozzoland cement  can binding solid waste sum of 10 weight % of (water + pozzoland cement) became the composite of waste concrete with the compressive strength of 577 ton/m2 and the chrome leaching test for 14 days of 0.059 mg/l.  The composite of waste concrete according to Bapedal rule for solidification of toxic waste with minimum compressive strength of 10 ton/m2 and maximum leached chrome of 5 mg/L.
Keywords: stabilization, solid waste, leather treatment, fly ash

## Termodinamika Adsorpsi Mg(II), Cd(II) dan Ni(II) Pada Silika Gel Termodifikasi Sulfonat

Keywords: adsorption, selectivity, silica gel, modification

## Pengaruh Konsentrasi Asam Terhadap Karakter Silika Gel Hasil Sintesis dari Natrium Silikat

ABSTRACT: In this research, synthesis and characterization  of silica gel from sodium silicate through sol-gel process using H2SO4, HCl, and citric acid have been investigated. Synthesis was carried out by mixing and stirring  20 mL of H2SO4, HCl or citric acid  at certain concentration with 50 mL of sodium silicate solution (Na2O 0.17 M and SiO2 0.61 M) for one hour and let to form gel.  The gel was washed with distillated water, and dried in an oven at 100oC. Characterization of silica gel was carried out by determination of acidity, water adsorption capacity, and water content. Identification of functional group and structure were identified using x-ray diffractometer (XRD) and infrared (IR) spectrophotometer, respectively.
Results showed that at a range of investigated concentration (0.6 – 3.0 M) the increase of concentration, formation of gel with H2SO4 tended to be faster, but with HCl and citric acid to be slower. The increase of acid concentration caused water content, water adsorption capacity, and acidity of the silica gel resulted with HCl and citric acid tended to be increased, increased, and increased, but with H2SO4  to be decreased, increased, and decreased, respectively. Based on the IR spectra and XRD data, it could concluded that the synthetic silica gels contained silanol (Si-OH) and siloxane (Si-O-Si) and were amorphous, showing similar pattern to kieselgel G 60 produced by Merck.
Keywords: silica gel, adsorption capacity, sodium silicate, acidity

## Kajian Isotop Karbon CO2 dan CH4 di Wilayah Barat Pegunungan Dieng dengan Gas Chromatography-Isotope Ratio Mass Spectrometer (GC-IRMS)

ABSTRACT: The carbon isotope can be used to evaluate volcanism phenomenon of volcano. The study of carbon isotope of CO2 and CH4 was carried out in western Dieng Plateau by mass-spectrometer. Before analysis, sampel was separated by gas chromatography using a Porapak-Q column and a FID (Flame Ionization Detector) detector. The gas was oxidized by copper oxide at 850oC before being ionized in mass-spectrometer for isotope analysis.
The CO2 content in Candradimuka crater (–4.10 O/OO), indicated that the gas may be as volcanic gas. The other CO2 from Sumber and western Gua Jimat, had isotope value  of -10.05 and -12.07  O/OO, respectively, indicating contamination from crustal and subduction material. The carbon isotope of CH4  gas from Pancasan village was -63.42 O/OO, that may be categorized as biogenic gas.
Keywords: isotope, CO2, CH4, Dieng

## Super (a,d)-edge-antimagic total labeling of connected Disc Brake graph

Abstract: Super edge-antimagic total labeling of a graph $G=(V,E)$ with order $p$ and size $q$, is a vertex labeling $\{1,2,3,...p\}$ and an edge labeling $\{p+1,p+2,...p+q\}$ such that the edge-weights, $w(uv)=f(u)+f(v)+f(uv), uv \in E(G)$ form an arithmetic sequence and for $a>0$ and $d\geq 0$, where $f(u)$ is a label of vertex $u$, $f(v)$ is a label of vertex $v$ and $f(uv)$ is a label of edge $uv$. In this paper we discuss about super edge-antimagic total labelings properties of connective Disc Brake graph, denoted by $Db_{n,p}$. The result shows that a connected Disc Brake graph admit a super $(a,d)$-edge antimagic total labeling for $d={0,1,2}$, $n\geq 3$, n is odd and $p\geq 2$. It can be concluded that the result has covered all the feasible d.
Author: Inge Yosanda Arianti, Dafik Dafik, Slamin

## Properties of Platinum Sub-Nanoclusters on Graphene Nano Sheets at Cathode

Abstract: The catalytic activities of Pt subnano-clusters on graphene nanosheets (GNS) for oxygen reduction reaction (ORR) catalysts have been examined. The ORR activity of Pt on GNS (0.99 V) is higher than on carbon black (CB) commercial catalyst (0.94 V versus RHE). A core level shift of Pt 4f in XPS indicates that Pt is chemically interacted with GNS. It has been ascribed to difference in the interface interaction between Pt and graphene via different strength of the π–d hybridization.
Keywords: Pt, Graphene nanosheet, Pt subnano-clusters, ORR

## On the Domination Number of Some Families of Special Graphs

Abstract: A domination in graphs is part of graph theory which has many applications. Its application includes the morphological analysis, computer network communication, social network theory, CCTV installation, and many others. A set $D$ of vertices of a simple graph $G$, that is a graph without loops and multiple edges, is called a dominating set if every vertex $u\in V(G)-D$ is adjacent to some vertex $v\in D$. The domination number of a graph  $G$, denoted by $\gamma(G)$, is the order of a smallest  dominating set of $G$. A dominating set $D$ with $|D|=\gamma(G)$ is called a minimum dominating set, see Haynes and Henning \cite{Hay1} . This research aims to find the domination number of some families of special graphs, namely Spider Web graph $Wb_{n}$, Helmet graph $H_{n,m}$, Parachute graph $Pc_{n}$, and any regular graph. The results shows that the resulting domination numbers meet the lower bound of an obtained lower bound $\gamma(G)$ of any graphs.

## Novel Mutations in the katG Gene in Isoniazid Resistant Mycobacterium tuberculosis Isolate

Abstract: Isoniazid (INH) resistance in Mycobacterium tuberculosis is commonly associated with mutations in katG encoding catalase-peroxidase.  A clinical isolate of M. tuberculosis L21 exhibits isoniazid resistant phenotype.  A 2.2 kb DNA fragment of katG gene from the L21 isolate had been cloned and characterized.  The L21 katG gene has four point mutations, namely T898C; G1388T; T1997C; C2035T; and one G2203 deletion.  The in silico translation analysis of the katG mutant suggests that the mutation results in a truncated protein lacking of 62 C-terminal amino acids with three amino acid substitutions, Trp300Arg, Arg463Leu, and Ile666Thr. The structural model superposition of the mutant protein with the full length protein suggests that the mutant losses an ability to form a dimer structure, and also posseses a distortion of intermolecular interactions in the substrate binding channel.
Keywords: katG gene, KatG, MDR M. tuberculosis, Isoniazid resistance, Structure model

## Auslander Reiten Quiver of Nakayama Algebra Nn-2,n

Abstract: For an algebraically closed field K, given a finite dimensional K-algebra A of  finite representation-type, we can store all the information of the module category mod A by its Auslander Reiten quiver of mod A. In this paper, we will determine the Auslander Reiten quiver of Nakayama algebra Nn-2,n  for every natural number n greater than or equal to 3, that is the  Nakayama algebra KQ/I where Q is a linear orientation cyclic quiver with  n  vertices and  I  denotes the ideal of the path algebra KQ generated by the paths of length of n – 1.
Keywords: AR-quiver, Nakayama algebra, Quiver

## NUMERICAL SOLUTION OF ABSORBING BOUNDARY CONDITIONS ON TWO DIMENSIONAL ACOUSTIC WAVE

Abstract: In this paper will be determined numerical solution of two-dimensionalacoustic wave equation with absorbing boundary conditions that obtained at Siddiq [9].Method used is determine nite di
erence equation in two-dimensional acoustic wave propagation problems satised absorbing boundary conditions.
Keywords: Two dimensional wave equation, Absorbing boundary conditions, Finite di
erence equation

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