Papers by Keyword: Spectroscopy

Abstract: Pandanus or the screwpines are nowadays, receiving more attention. It is the largest genera in Pandanaceae family. This species is usually found along coastal region from the Southeast Asia to the Pacific Island. Almost all parts of Pandanus species are used for many purposes in daily life. For example, the leaves are used as coloring and flavoring agents. Meanwhile, the bark and large branches are used in constructions. Besides the non-medicinal values, Pandanus species were also traditionally used as medications for the treatment of fever, headache, sore throat and others. Amazingly, some medical properties of Pandanus species are scientifically proven and the active constituents were known. The objective of this research is to investigate the biomolecule from Pandanus species, specifically, Pandanus pygmaues. It is aimed purify the chemical component that might present in the leaves part. In the methodology, the samples were cut prior to the organic solvent extraction and maceration. The compositions of Pandanus pygmaues extracts were detected via analytical and preparative thin layer chromatography. The hexane extract was subjected to an open column chromatography technique. A compound was successfully isolated and was analyzed by using Nuclear Magnetic Resonance spectroscopy. This compound could be identified as a tristearin.

Abstract: The knowledge on human tissue is very important to recognize desirable properties of biomaterials. Host cells, extracellular matrix, integrated vessels and interstitial fluids create a complex and dynamic system able to regenerate and respond to environmental stimuli. Myoglobin is a protein with most of α-helices on its secondary structure, and responsible for oxygen binding and release in muscles, by the heme group. This work investigates the Mb adsorption process onto zinc-hydroxyapatite (ZnHA) surface by spectroscopic studies. To do so, ZnHA (0.05 g) was incubated with 4mL of 2mg Mb/mL on phosphate buffer solution pH 6.0 for 24h at 37°C. The FTIR analyses of ZnHA powders before and after protein adsorption provided information concerning the protein content. UV-Vis spectrocopy in the reflectance mode suggested a mixture of MbO₂ and Met Mb on lyophilized solid Mb, and the prevalence of MetMb form when Mb was adsorbed on ZnHA sample. The decrease of UV-Vis secondary bands suggests interactions through the Mb heme group and the ZnHA surfaces. Circular Dichroism (CD) spectroscopy indicated the maintenance of the Mb α-helices secondary structure after the adsorption process on ZnHA powders.

Abstract: Antimony sulfide (Sb₂S₃) nanostructure was synthesized using a 600 W microwave irradiation technique. The precursors including Sb(CH₃CO₂)₃ and Na₂S₂O₃.5H₂O were dissolved into 50 mL ethylene glycol (EG) solution with containing 0 and 1 g of hydroxyethyl cellulose (HEC). Phase, morphology and optical properties of the as-synthesized products were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and photoluminescence (PL). Energy band gap of Sb₂S₃ nanostructure exhibits the value of 1.90 and 2.06 eV for synthesizing condition with and without HEC containing, respectively.

Abstract: Magnetite nanoparticle with average size 7-10 nm was embedded with biocompatible polyvinyl alcohol nanofiber and the average diameter of nanofiber is 115 nm. The nanofiber was further assembled over polymeric mesh to analyse the release mechanism of nanoparticles from polymer nanofiber. A hydrodynamics setup was constructed to study this system. Prior to hydrodynamics the nanofiber was allowed to react with water in static mode and observed that the magnetite nanoparticles were released from the nanofiber with increase in time. UV-Visible Spectrophotometer is used for analysis of absorbance and transmittance of polyvinyl alcohol-magnetite nanoparticles solution, nanofiber and films. High-resolution scanning electron microscopy is used to analyze the dimension of nanofiber; High-resolution transmission electron microscopy is used to find the size of magnetite nanoparticles. Here, an online spectroscopic technique was used to study the release mechanism of nanoparticles from nanofibers samples of different layers during hydrodynamics. The results reveal that the quantity of magnetite nanoparticles can be controlled by embedding into nanofibers during hydrodynamics. Also, the spectroscopic results indicate the quantity of nanoparticles released from nanofiber. This mechanism can be utilized to control the required quantity of nanoparticles to release at particular location through a polymer mesh assembly.

Abstract: The method of dielectric spectroscopy is an instrument of choice for the diagnosis of insulation used in high voltage and also to assess the quality of the insulation of HV equipment such as transformers, cables, capacitors, etc...This method allows to estimating the state and the quality of the insulation using the dielectric response of the frequency range. In this article, we have presented results of dielectric studies in high-density polyethylene (HDPE) by means of dielectric relaxation spectroscopy (DRS) in frequency range 10^-2 - 10⁶ Hz and temperature between-60 and 60 °C, we will invest this method to measure the dielectric properties and evaluate the performance of this insulator witch has always been chosen as a model polymer material because it is the simplest polymer with respect to its chemical structure and is used in a wide range of applications in daily life.

Abstract: Engineering, stability and orientation of semiconducting molecules are necessary to achieve the high efficiency of multifunctional organic-based devices. Several conjugated molecules facilitate the use of external magnetic fields to tailor both their molecular orientation and electronic properties while being processed for bio or opto-electronic applications. In this work, molecular thin films of vanadyl phthalocynine (VOPc) layers forming conducting channels in organic field-effect transistors were investigated. Three systems based on 100 nm thick VOPc thin film were grown, one in absence of magnetic field, while the other two with parallel and perpendicular to the substrate plane, respectively. Devices were ex-situ investigated by electrical characterization and confocal scanning Raman spectroscopy (SRS). All molecular layers growth on Au electrodes presented enhancement of the Raman signal.

Abstract: Aluminium borate nanowhiskers with varying aspect ratio were synthesized via sol–gel synthesis. The morphology of aluminum borate (Al₄B₂O₉ and Al₁₈B₄O₃₃) nanowhiskers could be controlled by varying the aluminum to boron (Al:B) molar ratio in the sol–gel derived precursors. Sintering temperatures (850 and 1100°C) and sintering times (4 and 32 hours) also affected the phase composition and size of the nanowhiskers. Citric acid was also added in the sol–gel derived precursors as a surface stabilizer for obtaining uniform finely dispersed nanostructures. Fine nanowhiskers were obtained by the calcination at 850°C, whereas higher temperature of 1100°C led to thicker and longer nanowhiskers and became rod-like crystals. The morphology and phase composition were investigated by field emission scanning electron microscope and X-ray diffraction. Chemical bond vibrations in the synthesized nanowhiskers were investigated by Fourier-transform infrared spectroscopy.

Abstract: Alkanolamines based carbon dioxide absorption from flue gases remains the most industrially implemented technique. The effective design of absorbers and associated equipment requires robust thermodynamic and kinetic models thus, instigating research efforts in chemical speciation and characterization of CO₂ loaded alkanolamine solutions. In this study, the potential of Raman spectroscopy has been investigated to determine the in situ chemical speciation in MDEA – CO₂ – Water system. The Raman spectra have been fitted to thermodynamic values using principal component regression. Results are in good agreement for carbonate, bicarbonate, MDEA and protonated MDEA chemical species.

Abstract: The growth and the atomic structure of alumina films of submonolayer to multilayer thickness evaporated onto the surface of Mo (110) crystal have been studied by Auger electron spectroscopy, high resolution electron energy loss spectroscopy and scanning tunneling microscopy. It is shown that the stoichiometry of the submonolayer film corresponds to that of the bulk oxide, and after achieving two monolayers the properties of the film largely resemble the properties of massive alumina. Deposition of the oxide at a substrate temperature of 1100 K results in the film structure corresponding to α-Al₂O₃. Such ultrathin oxide film is of considerable potential application in sensor physics and technology.

Abstract: Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) studied the interaction of argon ions with a natural oxide layer of polycrystalline aluminum. It was found that the bombardment of argon ions with an energy lower sputtering threshold Al₂O₃ leads to accumulation of ions bombarding the interstitial voids in the surface, thereby forming a solid solution of atoms of the target, the argon ions and nitrogen ion beam, the captured residual gas from the chamber of the spectrometer.