Jeong-Woo Choi

Detection of PC12 cells in-situ realized neurotransmitter using surface-enhancement Raman spectroscopy

A spun nanofibers were fabricated by electrospinning of polymer precursor solution containing polyvinyl alcohol/ zinc acetate. Novel ZnO/carbon nanofibers were prepared by annealing the as spun nanofibers in the nitrogen atmosphere. For investigation the effect of carbon presence in the samples, pure ZnO nanofibers were also prepared by annealing the as spun nanofibers in the air. The field emission scanning electron microscopy (FESEM) images indicated the smooth and beadless nanofibers. The wurtzite crystal structure of the nanofibers obtained by using x-ray diffraction (XRD). The band gap energy was estimated by diffuse reflectance spectroscopy (DRS) and Tauc model; and the results revealed band gap narrowing as a result of the carbon presence. Thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to investigate thermal behavior of the samples. Brunauer-Emmett-Teller (BET) data showed the carbon content in the nanofiber reduced the surface areas. The formation of Zn–O and Zn–OH bonds in the nanofiber surfaces was approved by X-ray photoelectron spectroscopy (XPS). The possible photo-degradation mechanism was studied by the examination of photocatalytic property in the presence of tert-butyl alcohol (t-BuOH) and I− anion as •OH radical and hole (h+) scavenger. The results showed that photodegradation of methylene blue molecules occurred by photo-generated electron. The existences of carbon in the nanofibers lead to the photocatalytic activity of the nanofiber under visible light.S and sensing response of pure and indium doped zinc oxide has been reported in this work. We adopted a chemical route to synthesize pure and doped ZnO. We have started with a 0.2M solution of ZnCl2 prepared in distilled water, in this solution indium chloride was added by weight. Then resulting solution was precipitated by adding an ammonium hydroxide drop wise at room temperature. The precipitates thus obtained were separated from rest of the liquids by filtering and were dried into powder at 120oC. Then the powders were sintered at temperature of 500oC for three hours.Double promoted γ-alumina heterogeneous base catalyst (CaO/KI/γ-alumina) was firstly developed for the production of biodiesel from palm oil in refluxed methanol. This study have been conducted in order to improve the activity of single promoted catalyst (CaO/γ-alumina) and to enhance the efficiency of biodiesel production that have been done in the previous work. The CaO/KI/γ-alumina catalyst was prepared by precipitation and impregnation methods. Engineering catalyst done with some parameters that effect on the activity of a catalyst among other: % CaO loading (wt. % against alumina), temperature and time of calcinations. The catalyst was characterized by mean of XRD, and BET methods. The activity of catalyst has been tested by introduced to the transesterification reaction of palm oil. The reaction was carried out in the batch type of reactor (three-neck glass flask with 500 ml capacity) equipped with reflux condenser, thermometer and magnetic stirrer. The result showed that the optimum condition of preparation catalyst (% of CaO loading, temperature and time of calcinations) were 30%, 650°C and 4.5 h, respectively. Under the optimum condition of catalyst, reaction temperature 65°C, reaction time 5 h and oil to methanol molar ratio of 1:42 the biodiesel yield was almost 95%. Therefore, it can be proved that the activity of double promoted catalyst (CaO/KI/γ-alumina) much higher than that the single promoted (CaO/γ-alumina) catalyst.USA gets the lead in nanotechnology and Japan, EU are in pursuit now. Korean government has begun to support the NT based R&D programs since 2001. Korean government supported many research institutions and companies financially to develop nanotechnology. There are much intensive competition to get the governmental fund among many nanocompanies such as SAMSUNG, LG, HYNIX, and many ventures. Korea has got remarkable performance in NT. The 1st half of this study reviews Korean governmental and industrial efforts for NT and evaluates Korean NT by comparing with other countries.M.R.Saber has completed his MSc from Fayoum University, Egypt. He joined Gabbai’s research group at the chemistry department, Texas A&M University, as a Fulbright visiting scholar for 10 months then he started his PhD in the Dunbar research group. He has published 4 papers in reputed journals and participated in several ACS meetings as well as the Austrian Physical Society Meeting 58 [OPG 58]. S Molecule Magnets (SMMs) are a remarkable class of molecules that display magnetic bistability of a molecular origin which arises from the combination of a high ground state electron spin (S) and a large negative zero-field splitting |D|. This magnetic bistability provides an excellent potential for molecular spintronics.We conducted a study of the conductive properties of polyelectrolyte polymer composite based on epoxy binder by electrochemical impedance spectroscopy, depending on the moisture content in it. Varied content of the polyelectrolyte in the polymer matrix and the thickness of coatings on steel substrate.Found that the conductivity of the material depends on its moisture content. The conductivity of the material in air-dry state is 28 MOhm × mm. When moisture content of about 0.5%(wt.) jump in conductivity percolation occurs, its value reaches about 68 KOhm × mm. Found that the coating thickness of 0,15-0,30 mm in the hydrated state allows the material to pass through a cathodic current required for protection of metal density, whereas in the dry state is an insulator. Conductive properties of the investigated polyelectrolyte composite can apply it when infliction to the metal structure before the conductive layer. The function of this layer is to reduce the electrical resistance in the presence of moisture between the coating and the metal structure that promotes the pervasion of cathodic protection current to the protected object, and in the absence of an aggressive environment in the metal to the sheilding, and as a consequence of reducing the cost of consumable cathode current.I the present study, extraction of platinum complexes from leach liquors of spent catalysts in aqua-regia into organic phase by the extractant trioctylphosphine oxide (TOPO) in toluene has been studied. platinum contained in the spent catalysts are leached out from the catalyst matrix by concentrated Hydrochloric acid and Nitric acid as the sole oxidizing agents in the form of chlorocompex [PtCl6] -2. We used alkaline metal salts as additives for enhancement of percentage of [PtCl6] -2 and distribution ratio of Platinum. Besides, effects of various parameters on the distribution ratio of platinum complexes has been investigated. We found KCl as the best alkaline metal salt which could affect both platinum extraction up to 90% and distribution of platinum complex at the desirable directs. Pt extraction had a very slight increase by time after the first half minute. It means that most of the Pt was extracted in the first 30 seconds. Therefore the equilibrium time is less than 30 seconds and the Pt extraction by TOPO is kinetically fast. This fact may resolve the problem of time-consuming extraction of Platinum by other extractants.O of the crack propagation in coatings is very important for the investigation on fracture mechanism. Fracture of plasma sprayed wollastonite coatings was observed in-situ using a Scanning Electron Microscope (SEM) during the Tapered Double Cantilever Beam (TDCB) specimens open. The fracture toughness was obtained subsequently. It is found that the initiation and crack propagation in coatings is discontinuous. The original pores in coatings can guide the cracking somewhat. The local principal stress also can influence the cracking propagation path. The lower fracture toughness of coatings, compared with the corresponding sintered materials, is partially affected by the crack propagating through the existing pores in coatings.N of Poly (amide-co-imide) PAI (torlon)/Poly (trimellitic anhydride chloride-co-4, 4’-methylene dianiline) (PTACM) blends have been prepared by using mechano-electrospinning. Employing mixed solvent systems of DMSO and THF and water coagulation bath as a medium, continuous fibers with improved mechanical properties have been obtained. The continuity of the fibers was strongly dependent on the solvent mixing ratio of DMSO and THF (6:4). Continuous fibers with the most uniform diameter were obtained when a 30% weight ratio of PAI and PTACM (1:1) resins were used in the blending solution. Further these continuous nanofibers were coated with silver nanoparticles via new route using PEG as a binding agent. The mechanical and electrically properties of these fibers dramatically enhanced after coating with silver nanoparticles. The properties of these blends were investigated using a rotational rheometer (AR 2000), SEM, Surface Tension Analyzer, and Universal Testing Machine in an attempt to understand the relationships between their rheological, morphological and mechanical properties.