The Density Functional Tight Binding (DFTB) Approach for Investigating Vacancy and Doping in Graphene as Hydrogen Storage

A study on graphene defects for hydrogen storage has been successfully conducted using the Density Functional Tight Binding (DFTB) approach. The research aimed to modify solid materials for hydrogen storage. A 4 × 4 × 1 unit cell was used as the basis, while the supercell used for sampling was enlarged to 40 × 40 × 1. The analyzed data included changes in Density of States (DOS), Fermi level shifts, electronic band structures, formation energy, adsorption energy, and isosurfaces for each graphene orientation. It has been observed that modifying the surface structure of graphene can alter the electronic properties of graphene. This is indicated by shifts in DOS intensity, characterized by increased electronic intensity around the Fermi level total density charge different. The interaction energy between graphene and hydrogen gas has been determined to be -0.0155 eV for H-epoxy graphene, -0.4941 eV for H-monovacancy graphene, and -0.0424 eV for HN-monovacancy graphene. The presence of the vacancy increase the potential to adsorp hydrogen

Cytotoxic Potential of Compounds Isolated from Non-Polar Fractions of Sungkai Plant Leaves (Peronema canescens Jack) Against Artemia salina Leach Larvae

The sungkai plant (Peronema canescens Jack), belonging to the Lamiaceae family, is a plant that is traditionally used as medicine, including toothache, malaria, and fever medicine. In this research, isolation was carried out with vacuum liquid chromatography (VLC), solid and liquid fractions were obtained. The solid fraction was further separated using column chromatography to obtain the isolated compound as a white solid (amorphous) weighing 10 mg (melting point 140˚C-142˚C). The results of the UV spectrum data show that there are no conjugated double bonds. The results of the IR spectrum show the presence of C-H groups at wave numbers 2921,49 cm-1 and 2856,94 cm-1, C=O groups at wave numbers, C=C groups at wave numbers 1641,51 cm-1, and dimethyl germinal which is characteristic of triterpenoid compounds at wave numbers 1456.68 cm-1 and 1372.41 cm-1. Meanwhile, the isolated oil was analyzed for chemical components using GC-MS. It was discovered that there were 83 chemical compound components contained therein with 4 main compound components, namely pentadecanoic acid (16.65%), 9,12-octadecanoic acid (16.12%), propyl palmitate (7.89%), and hexadecenoic acid, methyl ester (5.59%). A cytotoxic test was carried out on both fractions using the Brine Shrimp Lethality Test (BSLT) method. The results showed that the isolated compound was non-toxic with an LC50 value of 190214.2807 mg/L and the isolated oil was very toxic with an LC50 value of 34.2452 mg/L

Efektifitas Reaksi Transesterifikasi Minyak Kelapa dan Sereh untuk Pembuatan Perisa Alami dengan Biokatalisator Lipase serta Penggunaan Ultrasonik

In general, flavor are synthesis through enzymatic hydrolysis and esterification reactions (up to 20 hours) using commercial ingredients based on free fatty acids and alcohol. Efficient endeavors utilizing enzymatic transesterification to expedite reactions are necessary to acquire flavored products. Substrates may originate from commercial or natural sources abundant in fatty acids and alcohol. Commercial fatty acids and alcohol (geraniol) are readily available in pure forms. Alternatively, fatty acids can be sourced from coconut oil, while geraniol can be derived from lemongrass oil, which is more cost-effective compared to commercial ingredients. Ultrasonics have emerged as a means to expedite enzymatic. The objective of this study is to investigate the impact of ultrasonic power and transesterification reaction time between coconut oil and geraniol on geraniol conversion. Utilizing lipase (415.99 U/g), coconut oil was subjected to transesterification with commercially obtained pure geraniol in a 1:3 weight ratio, conducted in an ultrasonic tank filled with water. Reaction durations spanned 30, 60, 90, 120, and 150 minutes, with ultrasonic powers set at 50, 70, and 90 watts. The study findings elucidated that the highest geraniol conversion rate of 50.59% was achieved with 70 watts of ultrasonic power over a 90-minute period. These optimal conditions were subsequently applied to transesterify coconut oil with geraniol from lemongrass oil, yielding a conversion rate of 90.29%. This finding demonsttrate the posibility of employing coconut oil and lemongrass oil in a one-stage transesterification process to produce natural flavors via enzymatic lipase catalysis expedited by ultrasonic technology, facilitating swift reaction times

Front Matter

Marc

A New Insight Into Toxicity of Database Compounds from Ginger (Zingiber officinale) by Modelling Study

Dengue haemorrhagic fever (DHF) is an infectious disease caused by the dengue virus. The dengue virus is transmitted through female mosquitoes, especially Aedes aegypti and Aedes albopictus. Indonesia is a dengue endemic country, and almost all provinces in Indonesia are infected with dengue. However, targeted antiviral drugs against dengue virus (DENV) are not yet available. This study aimed to determine the potential of three compounds isolated from ginger (Zingiber officinale) as dengue NS2B/NS3 inhibitors, and to predict the physicochemical properties (drug-likeness) and potential toxicity of drug candidates. Ginger isolates in the form of [8]-gingerol, [6]-paradol, shogaol were obtained from the Natural Discovery Database (NADI). Toxicity and drug-likeness predictions were performed using ProTox-II and SwissADME, and Molecular Operating Environment (MOE) 2022.0901 was used for the molecular docking process. Results: The results showed that the ginger compound (Zingiber officinale), [8]-Gingerol, [6]-Paradol, and Shogaol, had binding free energy of -7.18, -7.10 and -6.88 kcal/mol, respectively. It is indicated that three compounds had  potentiality to inhibit the NS2B/NS3 protein complex with a binding free energy that was almost equivalent to that of the positive control, panduratin A, and similar to that of the positive control, which can be seen in superimposition. In addition, three compounds isolated from ginger met the drug-likeness parameters. Based on the analysis of in silico toxicity studies, the three compounds isolated from ginger showed different levels of toxicity. Therefore, based on the safety level of oral use, the [8]-gingerol compound is safer to develop as a dengue antiviral drug, where the LD50 value of [8]-gingerol is 2.580 mg/kg with a class V toxicity level that is practically nontoxic

Aktivitas Tabir Surya Secara In-Vitro Ekstrak dan Fraksi Daun Kedondong (Spondias dulcis Sol. Ex G.Forst)

Excessive sun exposure to the skin can cause redness (erythema) and darkening of the skin (pigmentation). This effect can be prevented by using sunscreen. Kedondong leaves (Spondias dulcis Sol. Ex G. Forst) can act as a natural sunscreen because they contain secondary metabolite compounds with a conjugated double bond structure (chromophore), including phenolic and flavonoid compounds. The presence of conjugated double bonds in phenolic and flavonoid compounds is known to be able to absorb UV radiation thereby reducing its intensity on the skin. This study aims to determine the sunscreen activity of kedondong leaves based on the Sun Protection Factor (SPF), , the percentage of erythema transmission value (%Te), and the percentage of pigmentation transmission value (%Tp) and determine the secondary metabolite groups in kedondong leaf extracts and fractions. The research stages carried out were extraction of kedondong leaves by maceration, dechlorophyllation, followed by fractionation using n-hexane and dichloromethane, to obtain methanol extract, n-hexane fraction, dichloromethane fraction and methanol fraction. Then phytochemical tests were carried out on the extracts and fractions. Phytochemical tests showed that the secondary metabolite compounds in the methanol extract of kedondong leaves were alkaloids, phenolics, steroids and saponins. Furthermore, in the n-hexane fraction are steroids, the dichloromethane fraction is phenolic compounds, and the methanol fraction is alkaloid, phenolic and saponin compounds. Using a UV-Vis spectrophotometer at a wavelength of 200-400 nm, the sunscreen activity test showed that the dichloromethane fraction at a concentration of 120 mg/L was included in the extra protection category with an SPF value of 7,86±0,23; fast tanning with a %Te value of 15,99±0,83 and sunblock with a %Tp value of 32,72±1,09

Minyak Atsiri Serai Wangi (Cymbopogon nardus L. Rendle): Diisolasi dengan Dua Metode Berbeda, Kualitas dan Aktivitas Antibakterinya

Cymbopogon nardus L. Rendle is one of the world trades essential oil plants. The high selling value of citronella oil is determined by the characteristics of its physical and chemical properties. In this study, determined the physical and chemical properties of citronellal oil isolated by two different methods, namely method of laboratory distillation (M1) and local community distillation (M2). The result showed that the essential oil produce from both methods match with SNI 06-3953-1995 on its physical properties. The results of the chemical composition using Gas Chromatography-Mass Spectrometry (GC-MS) indicated there are 38 and 48 compounds in the essential oil of M1 and M2, respectively with the main compositions are citronellal, citronellol, and geraniol. The antibacterial activity evaluated using the disc diffusion method showed inhibitory ability against the growth of Staphylococcus aureus and Staphylococcus epidermidis, but no inhibitory ability of Pseudomonas aeruginosa. Both, these M1 and M2 essential oils are categorized as a very strong antibacterial at concentration of 3.125% and 50%, respectively

Pemanfaatan Lumpur Lapindo sebagai Sumber Silika Magnetik untuk Adsorpsi Tumpahan Crude Palm Oil

In this paper, synthesis of silica magnetite adsorbent has been carried out from Lapindo Mud silica and magnetite (Fe3O4) using the template Cetyltrimethylammonium bromide (CTAB) through a microemulsion process. This research aims to determine the adsorption ability of magnetic silica material as an adsorbent for Crude Palm Oil (CPO) with varying contact times of 10, 20, 30, 60, 90 minutes and an adsorbate concentration of 0,2, 0,4, 0,6, 0,8 and 1 gram. Silica is obtained from Lapindo Mud extraction using the acid leaching method using HCl. Magnetite was prepared by mixing ferric chloride and ferrous chloride salts with an alkaline base. Synthesis of magnetic silica adsorbent using CTAB and 1-butanol as a surfactant and co-surfactant, respectively. The characterization results from FTIR and SEM-EDX data identified the presence of silanol (Si-OH) and Fe-O groups, magnetic silica adsorbent showed an irregular morphological pattern, the size tended to be heterogeneous, contained Fe, O and Si elements. The XRD results show that there are peaks in the (200), (311) and (440) planes, the GSA results show that the pore surface area is 37.048 m2/g, the total pore volume is 0.321 cm3/g and the pore diameter is 33.907 nm, which indicates that the pores have a mesoporous structure. Based on this research, the optimum contact time is 60 minutes with adsorption kinetics following the pseudo-second order and Langmuir isotherm with an adsorption capacity of 1.76 mg/g

Senyawa Isoflavonoid dari Akar Gitaan (Willughbeia coriacea Wall.)

Gitaan (Willughbeia coriacea Wall.) is an endemic plant that grows wild in the forests of Kalimantan. Traditionally, parts of this plant have been applied for fork-lore medication in Dayak tribe. However, scarce information both for secondary metabolites and biological activities of this plant has been reported, especially for flavonoids. This research was conducted to determine structure of flavonoid from ethyl acetate fraction of gitaan roots by spectroscopy analysis. The ethyl acetate fraction was purified by several chromatography techiques in order to isolate compound 1. On the basis of NMR analysis including DART-HRMS data and comparison with literature, an isoflavonoid obtained from the ethyl acetate fraction of gitaan roots is formononetin

Pemanfaatan Ekstrak Daun Sirih Hijau (Piper Betle Linn.) sebagai Capping Agent dalam Green Synthesis Spinel Ferit ZnFe2O4 untuk Remediasi Fenol dalam Air dan sebagai Anti Bakteri

The spinel ferrite material ZnFe2O4 was synthesized using a green synthesis approach by the hydrothermal method. In the synthesis, 2M NaOH was used as a mineralizer and betel leaf extract with varying volumes of 1, 3, 5, and 7 mL as a capping agent, then continued with calcination at 500, 600, and 700°C. Several devices, such as XRD, FT-IR, SEM-EDX, DRS-UV-Vis, and VSM, were used to characterize the synthesized ZnFe2O4 material. The pattern of XRD indicated that the ZnFe2O4 material has a cubic structure, where the increase in crystal size was after calcination. The Fourier Transform Infra-Red (FT-IR) spectrum shows the Fe-O interaction at wave numbers 427-417 cm-1, which is located on the octahedral side, while the Zn-O interaction at wave numbers 534-510 cm-1, which is located on the tetrahedral side in spinel ferrite structure. From the DRS UV-Vis spectrum pattern and band gap values, it was found that the material absorbs light in the visible region. Scanning Electron Microscope (SEM) images show that the morphology of the synthesized material is circular. The Vibrating Sample Magnetometer (VSM) hysteresis curve shows that the synthesized ZnFe2O4 has paramagnetic properties. The synthesized ZnFe2O4 material has photocatalytic activity towards phenolic compounds with a degradation percentage reaching 62.2%, and this material is active as an antibacterial with an inhibition area of 14.4 for S. aereus bacteria