Authors:Alviyanda Alviyanda, Gusti Muhammad Lucki Junursyah, Prihadi Sumintadireja Abstract: Biak Island is thought to have originated from the Australian Continental passive margin in the Mesozoic. This passive margin underwent tectonic collision to form the bedrock of Biak Island during the Paleogene. East Biak is covered by limestone, which is an obstacle to knowing the deeper stratigraphy. This study’s aim was to identify the subsurface geology of the East Biak area based on rock resistivity values. Magnetotelluric (MT) surveying is a passive geophysical method that is able to interpret subsurface geology based on rock resistivity values at depths of up to 5 to 10 km. The MT measurements in East Biak used 25 measurement points. Cross-sectional variations in rock resistivity values generated from the MT measurements were used to identify rock types in the East Biak subsurface. Five rock units were identified. The East Biak stratigraphy model is dominated by carbonates, comprising two sequences, i.e. an Early Neogene sequence with a thickness of 1,000 to 3,000 m and a Late Neogene to Quaternary sequence with a thickness of 180 to 2,450 m. The unconformity between these two sequences is due to tectonic activity, which separated Supiori and Biak Island. PubDate: 2020-09-08 Issue No:Vol. 52 (2020)
Authors:Sabarinsyah Sabarinsyah, Hanni Garminia, Pudji Astuti Abstract: This paper introduces continuous-like linear operators on bilinear spaces as a generalization of continuous linear operators on Hilbert spaces. It is well known that the existence of the adjoint of a linear operator on a Hilbert space is equivalent to the operator being continuous. In this paper, this result is extended to the class of linear operators on bilinear spaces. It is shown that the existence of the adjoint of a linear operator on a bilinear space is guaranteed if and only if the operator is continuous-like. PubDate: 2020-09-08 Issue No:Vol. 52 (2020)
Authors:Hamza Abd Hamza Abd El-Qader, Ahmad Termimi Ab Ghani, Izzat Qaralleh Abstract: The current study provides a new class of ξ(as)-QSO defined on 2D simplex and classifies it into 18 non-conjugate (isomorphic) classes. This classification is based on their conjugacy and the remuneration of coordinates. The current study also examines the limiting points associated with the behavior of trajectories for four classes defined on 2D simplex. PubDate: 2020-09-06 Issue No:Vol. 52 (2020)
Authors:Bambang Tri Purwanto, Siswandono Siswandono, Suko Hardjono, Dian Triwidiandany Abstract: Urea derivatives are extensively used in the pharmaceutical industry. However, the unsatisfactory level of their membrane penetration requires further modification of the structures with stronger lipophillic properties. Phenylurea has a phenyl group that enables easier membrane penetration as a result of stronger pharmacological activity. Activity prediction was conducted by docking experiments and molecular dynamics, performed with Molegro Virtual Docker 5.5 using checkpoint kinase 1 (CHK1) enzyme with ID PDB: 2YWP. ADMET prediction was applied to collect data using the pkCSM tool. N-(phenyl carbamyol)benzamide compounds, modified by the Schotten Baumann method, were synthesized from benzoil chloride reacting with N-phenylurea. For evaluating anticancer activity, the MTT assay method on HeLa cells was used. Derived from the docking experiments, the compound rerank score of the N-(phenylcarbamoyl)benzamide was 72.0603 kcal/mol, lower than that of hydroxyurea, -32.1514 kcal/mol, causing better inhibitory activities against HeLA cell lines due to higher cytotoxic effects. ADMET Predictor was employed, indicating satisfactory compound distribution with a low, favorable metabolism, possessing good excretion and non-toxicity. The synthesized compound was 82% N-(phenyl carbamoyl)benzamide with 0.8 mM IC80, higher than that of hydroxyurea, 4.3 mM. In conclusion, successfully synthesized N-(phenylcarbamoyl)benzamide was proved to have higher cytotoxic effects. The satisfactory values of these compounds indicate that they are promising anticancer drug candidates. PubDate: 2020-09-06 Issue No:Vol. 52 (2020)
Authors:Sibel Yalçın, Şahsene Altınkaya, Gangadharan Murugusundaramoorthy, Kaliappan Vijaya Abstract: In this investigation a new subclass of bi-univalent functions is established that is defined in the open unit disk Δ={ðŒ¶ ∈ ℂ: ðŒ¶ < 1} and are endowed with the Sălăgean type q-difference operator. Then, Hankel inequalities for the new function class are obtained and several related consequences of the results are also stated. PubDate: 2020-09-06 Issue No:Vol. 52 (2020)
Authors:Imam Kambali, Rajiman Rajiman, Parwanto Parwanto, Marlina Marlina, Kardinah Kardinah, Nur Huda, Ferdi Dwi Listiawadi, Herta Astarina, Ratu Ralna Ismuha, Heranudin Heranudin, Hari Suryanto Abstract: Due to the declining number of available nuclear reactors capable of Tc-99m production and tight regulations related to uranium enrichment, cyclotron-based Tc-99m production has recently been suggested as a new method to help ease Tc-99m supply shortages. In this investigation, a solid natural MoO3 target was irradiated using 11-MeV proton beams at variable proton doses. The proton doses were varied by varying the irradiation time while keeping the proton beam current constant at 20 µA. At the end of the bombardment, the post-irradiated solid MoO3 targets were analyzed for their radioactive contents using a portable gamma-ray spectroscopy system. The analysis was also performed for the post-irradiated targets after dissolving the solid MoO3 in a 6M NaOH solution. The experimental results indicated that as much as 75.71% of Tc-99m radioactivity was directly generated via a 100Mo(p,2n)99mTc nuclear reaction, while the rest of the Tc-99m radioactivity was a result of a 98Mo(n,γ)99Mo→99mTc nuclear reaction. Apart from Tc-99m and Mo-99 radionuclides, some other radionuclides such as N-13, Tc-96, and Nb-96 were also recorded following temporal observation of the NaOH-dissolved MoO3. These experimental results open up the possibility of direct production of Tc-99m using a proton-accelerating cyclotron. PubDate: 2020-09-06 Issue No:Vol. 52 (2020)
Authors:Denny Riama Silaban, Edy Tri Baskoro, Saladin Uttunggadewa Abstract: Harary and Miller (1983) started the research on the (restricted) size Ramsey number for a pair of small graphs. They obtained the values for some pairs of small graphs with order not more than four. In the same year, Faudree and Sheehan continued the research and extended the result to all pairs of small graphs with order not more than four. Moreover, in 1998, Lortz and Mengenser gave the size Ramsey number and the restricted size Ramsey number for all pairs of small forests with order not more than five. Recently, we gave the restricted size Ramsey number for a path of order three and any connected graph of order five. In this paper, we continue the research on the (restricted) size Ramsey number involving small graphs by investigating the restricted size Ramsey number for matching with two edges versus any graph of order five with no isolates. PubDate: 2020-09-01 Issue No:Vol. 52 (2020)
Authors:Muhamad Jalil Baari, Bunbun Bundjali, Deana Wahyuningrum Abstract: Oligosuccinimide (OSI) is an oligomer with several repeating units of succinimide. In this study, OSI was synthesized by thermal condensation between maleic anhydride and ammonium carbonate. The chemical structure of the synthesized compound was confirmed by FTIR and NMR spectroscopy as well as LC-MS characterization. Evaluation of its performance as corrosion inhibitor and the adsorption mechanism on a carbon steel surface in CO2-saturated 1% (w/v) NaCl solution was performed using electrochemical techniques (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization) and weight-loss methods. These tests were simultaneously carried out for all fractions without separation. The EIS results showed that the inhibition efficiency (IE) of the OSI increased with increasing concentration but decreased at higher temperatures. The potentiodynamic polarization data indicated that the OSI acted as a mixed inhibitor. Adsorption of OSI on the carbon steel generally obeys the Langmuir adsorption isotherm according to curve linearity, which relates the degree of surface coverage to the inhibitor concentration. The standard Gibbs free energy of the adsorption values (∆G° ads) were negative within the range of -33.14 to -38.73 kJ.mol-1, which indicates the spontaneity of the adsorption process on the carbon steel surface and that OSI molecules interacted with the carbon steel through semi-physisorption. PubDate: 2020-09-01 Issue No:Vol. 52 (2020)
Open Access journal
[13 journals]
