Journal of Mathematical and Fundamental Sciences
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Linear and Nonlinear Electro-optic Response of MHPOCBC
Full text linkThis study investigated the linear and second-order electro-optic responses in chiral smectic liquid crystal 4-(1-methylheptyloxycarbonyl) phenyl 4-octylcarbonyloxybiphenyl-4-carboxylate (MHPOCBC). The result revealed a single Debye-type relaxation in the linear electro-optic frequency dispersion, with a relaxation frequency extending up to one hundred kHz. Conversely, the second-order electro-optic response exhibited intricate temperature-dependence, accurately depicted by a phenomenological Landau theory around the SmA–SmCa* phase transition point. Notably, in the SmCa* phase, critical slowing down of the amplitude mode occurred near the transition to the SmA phase, while at lower temperatures of the SmCa* phase, a distinct low-frequency relaxation mode emerged. Furthermore, the relaxation frequency of the antiferroelectric Goldstone mode in the SmCA* phase remained constant across the entire temperature range. These findings should significantly contribute to the understanding of dynamic behaviors in chiral smectic liquid crystals, shedding light on their complex phase transitions and electro-optic properties
Particle Size Optimization of Melinjo (Gnetum gnemon L.) Seed Hardshell: A Potential Antioxidant Alternative
Full text linkNatural ingredients can have extraordinary potential as alternative medicines due to their accessibility and cost-effectiveness. Application of these ingredients should consider solubility and permeability, which determine the success of pharmaceutical characteristics formulation and biological activity indication. In this context, physical manipulation, specifically particle size reduction, is an effective strategy to address these issues. Previous research has explored active compounds in the stilbenoid group, found in the outer skin, hard shell, and endosperm of melinjo (Gnetum gnemon L.) seeds, functioning as antioxidant. Based on the potential as antioxidant, stilbenoid compounds, including resveratrol, contained in melinjo seed hardshell have shown significant pharmacological effects. Therefore, this research aimed to investigate the potential of melinjo seed hardshell extract as a natural antioxidant alternative by modifying the particle size through a grinding process to obtain nanoparticles. The analysis was carried out using ball milling to enhance the solubility of melinjo seed hardshell extract by increasing the saturated solubility and surface area of the particles. The results showed that the total phenol content and the antioxidant power increased significantly (p < 0.05) after ball milling. Melinjo seed hardshell nanoextract is reported herein as a promising source of natural antioxidant from local Indonesian plants
Geochemistry of I-type Volcanic Arc Granitoid From Tanggamus Regency, Southern Sumatra
Full text linkGranitoid intrusion of several provinces on Sumatra is correlated with Southeast Asia tectonics that have occurred since the Permian. Granites from several volcanic arc provinces are located along the western part of Sumatra Island and are found near Bukit Barisan. This study describes the geochemical character of granitoid from the Tanggamus region and its surroundings near the Bukit Barisan cluster. After megascopic description in the field, major oxides, trace elements, and rare earth elements in rock samples were measured using X-ray fluorescence and inductively coupled plasma-mass spectrometry devices. The samples were intermediate to acidic intrusive rocks with SiO2 ranging between 61.35% and 75.29%. The rocks can be described as diorite to granodiorite and were formed as a result of subduction processes. The granitic rock samples showed I-type features of A/CNK value <1.1, volcanic arc granite affinity, K2O/Na2O ratio, and magnesian properties. The total rare earth content was medium with an average of 43.97 ppm. The similarity of the rare earth normalized diagram against the chondrite value indicates that the samples come from an identical origin
A Pyrone and Flavonoid Derivatives from Cryptocarya crassinervia and their Inhibitory Properties against Receptor Tyrosine Kinases
Full text linkA new a-pyrone, i.e., cryptocrassinervione (1), and a new flavone glycoside, i.e., kaempferol-3-O-rhamnosyl-2-O-apiofuranoside (4), were isolated from EtOAc extract of Cryptocarya crassinervia leaves. Along with these compounds, two known flavone glycosides, namely afzelin (2) and quercitrin (3), were also isolated. The structures of the new compounds were determined based on NMR and mass spectral data. Compounds 1–4 were examined against eight receptor tyrosine kinases (RTKs) (EGFR, HER2, HER4, IGF1R, InsR, KDR, PDGFRα, and PDGFRβ), which showed that these compounds were moderately active against EGFR, with inhibition percentages of 55, 49, 41, and 44%, respectively. They were weakly active against HER2, with inhibitions of 17, 20, 18, and 16%, respectively. However, they were not active against the rest of the RTKs. Nevertheless, compounds 1–4 have potency as inhibitors of EGFR
Cytotoxic Effect of Benzofuranoid Neolignans from Myristica fragrans Seeds Against Melanoma B16-F10 Cancer Cells
Full text linkMyristica fragrans is an indigenous plant in Indonesia, characterized by various secondary metabolites with diverse bioactivities. This plant possesses promising anti-melanoma properties capable of addressing prevalent cases of melanoma. Therefore, this study’s objective was to isolate potential compounds from Myristica fragrans seeds and assess their cytotoxic effects on melanoma B16-F10 cells. Ethyl acetate extracts were subjected to separation through various chromatographic methods to obtain three benzofuranoid neolignans, which was conducted using spectroscopic analyses, namely UV-vis, polarimeter, HRTOF-MS, IR, and NMR. Subsequently, comparison with previously reported spectral data confirmed the identities of neolignans as (+)-licarin A (1), (+)-licarin B (2), and (+)-maceneolignan B (3). Cytotoxicity against melanoma B16-F10 cells was assessed using the PrestoBlue method, revealing (+)-licarin A (1) to display the most potent activity with an IC50 value of 94.15 μM
Structural and Magnetic Properties of Barium-Strontium-Hexaferrite Material Ba0.6Sr0.4Fe10-xCoxMnTiO19 (x = 0.5; 1.0; and 1.5) as Microwave Absorbers
Full text linkWe discuss the structure properties of Ba0.6Sr0.4Fe10-xCoxMnTiO19(BSFCMTO) for x = 0.5, 1.0, and 1.5 that influence its magnetic properties as a microwave absorber. A solid-state reaction method using high-energy milling was used to synthesize hexaferrite. There were no structural changes when the Co2+ ion was substituted for the Fe3+ ion; the structures of all samples were hexagonal and the space group was P63/mmc. The surface morphology had heterogeneous particles with a size of 300 to 600 nm. The magnetic properties tended to decrease with an increasing number of Co2+ ion substitutions. The reflection loss (RL) had a minimum value of -14.89 dB. This value was reached at a frequency of 10.96 GHz and had a bandwidth at 1.24 GHz with a sample thickness of 1 mm in the Ba0.6Sr0.4Fe9.9Co0.1MnTiO19 sample
Implementation of Non-Uniform F-K and Strict F-K Filter Normalization in Seismic Downhole Processing
Full text linkIn fundamental geophysics, we can understand that if we hit the surface, the body and surface waves propagate into and on the soil or rock. The body waves consist of pressure waves, which are the fastest, and shear waves, which are slower. This phenomenon can be measured using the seismic downhole method to determine the velocity of P and S waves of soil layers by generating source energy at the surface and calculating the arrival time at a tri-axial sensor inside a borehole. Determining the arrival time of S waves is often tricky because the recorded S wave arrival is on the coda of the P waves and is also distracted by measurement noise. A common method to separate P and S waves is direct F-K filtering from the F-K image of the measurement data. This study modified this method by adjusting the actual source-receiver distance by implementing a non-uniform F-K transform to produce the correct velocity response. Another improvement was strict filter normalization to regain continuity, thus preventing a shadow response in the F-K image. Synthetic and real measurement data showed that our modification performed better than direct FK-filtering
Structural and Photoluminescence Properties of Ca2+-Substituted Self-Activated Photoluminescence Material of Na2TiSiO5
Full text linkThe effects of Ca2+ substitution on the structural and optical properties of Na2TiSiO5 were studied. It was expected that the Ca2+ ions would replace Na+ ions and change the coordination of Ti4+-O2- as a luminescence center. Na2(1‑x)CaxTiSiO5 (x = 0.00, 0.50, 1.00) samples were synthesized using the solid-state method, and their structural properties, the local Ti4+-O2- coordination, the absorption spectra, and the photoluminescence properties were studied. The electronic structure of Na2(1-x)CaxTiSiO5 with x = 0.00 and 1.00 was also calculated using the Full Potential Linear Augmented Plane Wave (FP-LAPW) method to explain some of the observed properties. The Ca2+ substitution resulted in a phase transformation from an orthorhombic to a monoclinic structure. The number of TiO6 octahedra increased with the increase of Ca2+ and correlated with the decrease of PL emission intensity of the Na2(1‑x)CaxTiSiO5 samples. The Ti-3d bands in the CaTiSiO5 were more dispersive than in the Na2TiSiO5 and were responsible for the PL emission intensity reduction
Environmentally Friendly Graphene Oxide Production using Ultrasonication for Fiber Optic Coating as Humidity Sensor
Full text linkGraphene oxide (GO) has many applications, such as energy storage, sensors, and polymer composites. This study aimed to produce environmentally friendly GO for use as a humidity sensor. The GO was synthesized using liquid phase exfoliation (LPE) with ultrasonication. The ultraviolet-visible (UV-Vis) test results showed an absorption peak at a wavelength of 227 nm and a shouldering peak at 270 nm. The Fourier transform infrared (FTIR) spectrum showed the presence of oxygen functional groups indicating hydrophilic material characteristics. The X-ray diffraction (XRD) patterns indicated that the GO had an amorphous phase, as evidenced by a broadened peak at 2θ ≅ 12.2°. The scanning electron microscope (SEM) images showed that the synthesized GO was in the form of indentations or sheets of planar hexagonal structures in single or multi-layers. Based on the energy dispersive X-ray (EDX) characterization, the GO consisted of 63.6% carbon (C) and 26.4% oxygen (O). The C/O ratio after sonication showed a reduction in oxygen with a ratio of 2.4. Interestingly, the humidity tests showed that the GO coated on polymer optical fiber (POF) significantly enhanced the gradient values from 0.0567 to 0.4042 compared to the POF without coating, confirming its potential as a humidity sensor.
Rapid Synthesis of Graphene Oxide Derived from Biomass with Atmospheric Plasma Technology
Full text linkIn this study, we explored a low-cost, green, and renewable approach utilizing biomass resources, i.e., coconut fronds, palm fronds, and rambutan stems, to rapidly synthesize graphene oxide via atmospheric plasma techniques. The plasma treatment, with argon gas as the plasma source and a power source of 960 W, lasted for 5 minutes. Graphene oxide (GO) was confirmed using SEM and TEM images with a C:O content ratio greater than 80% for all samples and the formation of graphene layers. The presence of a D-band and a G-band in Raman spectroscopy as well as O-H and C-O groups in the FTIR confirmed the existence of GO