Earticle

New synthetic route and characterization of alkyl-capped nanocrystalline silicon (R-n-Si) were achieved from the reaction of silicon tetrachloride with sodium/benzophenone ketal reducing agent followed by n-butyllithium. Surface of silicon nanoparticles was derivatized with butyl group. Effect of oxidation of silicon nanoparticle with benzophenone was investigated for their stabilization. Optical characteristics of silicon nanoparticles were characterized by fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), and photoluminescence (PL) spectroscopy. Butylcapped silicon nanoparticles exhibited an emission band at 410 nm with excitation wavelength of 360 nm. Average size of n-butyl-capped silicon nanoparticles was obtained by particle size analyzer (PSA) and transmission electron microscopy (TEM). Average size of n-butyl-capped Si nanoparticles was about 6.5 nm.

Polystyrene thin films containing Bragg structures have been successfully obtained by the removal of DBR porous silicon films from the DBR structured porous silicon/polystyrene composite film in HF/H2O mixture solution and by replicating the nano-structures of porous silicon containing Bragg structure. Polystyrene thin films containing Bragg structures displayed unique optical reflection resonances in optical reflection spectrum. This optical reflection band was resulted from the interference of reflection wavelength at Bragg structure of polystyrene thin films. The wavelength of reflection resonances could be modified by the change of Bragg structure of the master. Polystyrene thin films containing Bragg structures were flexible and maintained their optical characteristics upon bending. The Polystyrene thin films replicate the photonic features and the nanostructure of the master.

Since it is of great importance to know how a ligand binds to a receptor, there have been a lot of efforts to improve the quality of prediction of docking poses. Earlier efforts were focused on improving search algorithm and scoring function in a docking program resulting in a partial improvement with a lot of variations. Although these are basically very important and essential, more tangible improvements came from the reduction of search space. In a normal docking study, the approximate active site is assumed to be known. After defining active site, scoring functions and search algorithms are used to locate the expected binding pose within this search space. A good search algorithm will sample wisely toward the correct binding pose. By careful study of receptor structure, it was possible to prioritize sub-space in the active site using “receptor-based pharmacophores”or “hot spots”. In a sense, these techniques reduce the search space from the beginning. Further improvements were made when the bound ligand structure is available, i.e., the searching could be directed by molecular similarity using ligand information. This could be very helpful to increase the accuracy of binding pose. In addition, if the biological activity data is available, docking program could be improved to the level of being useful in affinity prediction for a series of congeneric ligands. Since the number of co-crystal structures is increasing in protein databank, “Ligand-Guided Docking”to reduce the search space would be more important to improve the accuracy of docking pose prediction and the efficiency of virtual screening. Further improvements in this area would be useful to produce more reliable docking programs.

Photoluminescence properties and surface morphologies of porous silicon etched with various applied current densities at fixed etching times. FE-SEM image of porous silicon surface indicated that the porous silicon prepared at currents below 200 mA exhibited very bright red photoluminescence properties. As the applied current densities increased, the photoluminescence efficiencies of porous silicon prepared at applied current densities above 300 mA decreased, and displayed the cracked surface on porous silicon. This crackεd surface start to collapsed to give cracked domains.

Oxidation behaviors of porous silicon were investigated by the measurement of area of SiO2 vibrational peaks in FTIR spectra during thermal oxidation of porous silicon at corresponding temperatures. Visible photoluminescent porous silicon samples were obtained from an electrochemical etch of n-type silicon of resistivity between 1-10 Ω/cm. The etching solution was prepared by adding an equal volume of pure ethanol to an aqueous solution of HF. The porous silicon was illuminated with a 300 W tungsten lamp for the duration of etch. Etching was carried out as a two-electrode galvanostatic procedure at applied current density of 200 mA/cm2 for 5 min. The porosity of samples prepared was about 80%. After formation of porous silicon, the samples were thermally oxidized at 100oC, 200oC, 300oC, and 400oC, respectively. The growth rate of SiO2 layer of porous silicon was investigated by using FT-IR spectroscopy. The effect of oxidation of porous silicon was presented.

New low temperature synthesis of germanium nanoparticles obtained from the reaction of germanium tetrachloride and sodium/benzophenonewere developed. These germanium nanoparticles terminated with chloride group were oxidized in air to give hydroxy-terminated germanium nanoparticles. Germanium nanoparticle containing 20(S)-camptothecin (CPT) for a noble drug delivery system were developed. FT-IR spectroscopy was used for the characterization of vibrational absorption for the germanium nanoparticle and oxidized germanium nanoparticles containing camptothecin. Electronic absorption and fluorescence properties were measured with UV-Vis and fluorescence spectrometer. The morphology of oxidized germanium nanoparticles containing camptothecin was investigated by using TEM.

A pseudoreceptor combines structure-based and ligand-based techniques to represent a unifying concept for both receptor mapping and ligand matching. In this molecular modeling approach, there are opportunities to construct the pseudoreceptor models using a set of small molecules. To build a reliable pseudoreceptor model, we need a set of ligand molecules with known affinity (biological activity) to generate 3D bioactive conformation for each of these ligand molecules. Several software packages are available to generate a pseudoreceptor model and this can provide an entry point for structure based drug discovery in cases where receptor structure information is not available. In this review, we presented the concept of pseudoreceptor, as well as discussed about various software packages available to generate a pseudoreceptor model

Novel porous silicon chip exhibiting dual optical properties, both Frbry-Perot fringe (optical reflectivity) and photoluminescence had been developed and used as chemical sensors. Porous silicon samples were prepared by an electrochemical etch of p-type sillicon wafer (boron-doped, <100> orientation, resistivity 1 - 10 Ω). The ething solution was prepared by adding an equal volume of pure ethanol to an aqueous solution of HF (48% by weight). The porous silicon was illuminated with a 300 W tungsten lamp for the duration of etch. Ething was carried out as a two-electrode Kithley 2420 preocedure at an anodic current. The surface of porous silicon was characterized by FT-IR instrument. The porosity of samples was about 80%. Three different types of porous silicon, fresh porous silicon (Si-H termianated), oxidized porous silicon (Si-OH terminated), and surface-derivatized porous silicon (Si-R terminated), were prepared by the thermal oxidation and hydrosilylation. Then the samples were exposed to the wapor of various organics vapors. such as chloroform, hexane, methanol, benzene, isopropanol, and toluene. Both reflectivity and photoluminescence were simultaneously measured under the exposure of organic wapors.

This study was conducted to investigate the major chemical components of dried Capsosiphon fulvescens. The proximate compositions of C. fulvescens as dry matter basis were the moisture content 6.27%, 27.66% of crude protein, 1.68% of crude fat, 10.69% of crude ash, and 53.70% of carbohydrate, respectively. Analysing total amino acids, 17 kinds of components isolated from C. fulvescens. The essential amino acid contained in C. fulvescens accounted for 42.33% of total amino acid, while the non-essential amino acid accounted for 57.67%. Fatty acids were of 13.34% of saturated fatty acids, 21.69% of monounsaturated fatty acids and 64.97% of polyunsaturated fatty acids. Linoleic acid, oleic acid, palmitic acid and linolenic acid were the major fatty acids among 14 fatty acids detected in dried C. fulvescens. Oxalic acid was the major organic acids. The contents of vitamin A and vitamin E were 0.021 mg% and 0.001 mg%, respectively. The mineral contents of dried C. fulvescens were greater in order of Mg<Na<K<Fe<Zn<Mn<Cu. These results suggest that C. fulvescens are able to recommend as a vegetable of highly nutritional quality.

This study was conducted to find associations of obesity, exercise pattern and nutrient intakes in Korean American immigrants residing in North Western parts of USA. The structured survey forms and food frequency questionnaire that covered 67 food items were used. There was a significant difference in height for subjects by gender and age. However, the weight of females became heavier with increasing age in contrast to males. There was a great difference in BMI between the male and female group in the youngest adult group compared to the aging adults. Significant age difference in exercise pattern was shown. Dietary fiber and sodium intakes were higher in the elderly than young ones in female group. In the same young adult group Zn intakes was the highest in the male group and the lowest in the female group. Folate intakes were higher in females than in males. Strong positive correlations among height, weight and BMI were shown. Zn intake was significantly correlated with weight, height, and exercise pattern in the study. Furthermore, Zn was correlated with sodium, vitamin B6, folate, vitamin E and cholesterol.