• Transactions of the Korean Society of Mechanical Engineers B
• /
• 제29권1호
• /
• pp.131-138
• /
• 2005

Thermo-osmosis of liquids in a microscale channel is investigated by theoretical and simulation study. From the basic set of conservation equations, the temperature and velocity distributions are derived in the function of the given temperatures and pressure gradient. The pressure gradient for a given temperature gradient is then obtained by the molecular simulation. It is shown that the temperature gradient tangential to the surface induces the pressure gradient and thus the flow in the interfacial region between the liquid and channel surface. The thermo-osmotic flow is proportional to the applied temperature gradient, and the factor of proportionality depends on temperature and intermolecular potential. The origin and characteristics of the phenomenon are discussed in molecular details.

• Journal of the Korean institute of surface engineering
• /
• 제39권2호
• /
• pp.64-69
• /
• 2006

Nanoscale task such as nanolithography and nanoindenting is a challenging work that is beyond the capabilities of human sensing and precision. Since surface forces and intermolecular forces dominate over gravitational and other more intuitive forces of the macro world at the nanoscale, a user is not familiar with these novel nanoforce effects. In order to overcome this scaling barrier, haptic interfaces that consist of visual and force feedback at the macro world have been used with an Atomic Force Microscope (AFM) as a manipulator at the nanoscale. In this paper, a nanoscale virtual coupling (NSVC) concept is introduced and the relationship between performance and impedance scaling factors of velocity (or position) and force are explicitly represented. Experiments have been performed for nanoindenting and nanolithography with different materials in the nanoscale virtual surface. The interaction forces (non contact and contact nanoforces) between the AFM tip and the nano sample are transmitted to the operator through the haptic interface.

• YAKHAK HOEJI
• /
• 제33권4호
• /
• pp.246-252
• /
• 1989

2-Amino-1-N-methyl benzamide, 2-N-benzyl amino benzamide, 2-N-phenyl amino benzamide of 2-amino benzamide derivatives were reacted with ${\alpha}-bromo$ acetaldehyde diethyl acetal in basic condition. 2-N-alkylated products were prepared from 2-amino-1-N-methyl benzamide and 2-N-phenyl amino benzamide. 1-N-benzyl-1.4-benzodiazepin-5-one was prerpared from 2-N-benzyl aminobenzamide via intramolecular cyclization. However, 2-amino-1-N-methyl benzamide with sodium amide did not react to 1.4-benzodiazepin-5-one derivative but 3-methyl-quinazoline-2.4-dione was obtained.

• Archives of Pharmacal Research
• /
• 제10권4호
• /
• pp.232-238
• /
• 1987

The molecular structure of naproxen determined by X-ray diffraction technique was refine to the final R-value geing 0.042. The compound was recrystallized from ethanol solution in monoclinic crystal system, space group $P2_1$ , with Z = 2, a = 13.375(5) $\AA$, b = 5.793(2) $\AA$, c = 7.914 $\AA$, $\beta$=93.91(3)$\AA$ and $d_{obs}$ = 1.26, $d_{calc}$ = 1.25 g/cm$^{3}$. The structure was solved by direct method and refined by block diagonal least squares procedure for 747 relfections (F .leq. 6.sigma.(F)). The molecules are connected by two intermolecular OH--O type hydrogen bonds.

• Archives of Pharmacal Research
• /
• 제8권1호
• /
• pp.1-6
• /
• 1985

The crystal structure or $\gamma$-hydroxy-$\betha$-aminobutyric acid was determined by MULTAN system with X-ray intensity data on a diffractometer and refined by the least-squares method to an R-value 0.034 for 711 reflections. The crystals were orthorhombic, space group $P2_{1}2_{1}2_{1}$, Z = 4, with a = 10.220, b = 8.257 and c = 6.556$\AA$. The molecule takes the zwitterionic form and skeletal conformation is trans-transform. The molecules are held together by intra-and intermolecular NH-O and OH--O hydrogen bonds.

• Bulletin of the Korean Chemical Society
• /
• 제27권4호
• /
• pp.463-472
• /
• 2006

The preparation of enatiomerically enriched homoallylic alcohols through asymmetric addition of chiral allylic transfer reagents and allylating reagents with chiral catalysts to the carbonyl functionalities represents an important chemical transformation. Excellent progress has been made over past decade in the development and application of catalytic asymmetric allylic transfer reactions. In this account, our efforts for the various intermolecular allylic transfer reactions such as allylation, propargylation, allenylation, and dienylation utilizing accelerating strategy and sequential allylic transfer reactions to achieve multiple stereoselection mainly using transition metal catalysts are described.

• Fibers and Polymers
• /
• 제1권2호
• /
• pp.71-75
• /
• 2000

Intermolecular cyclization of 2-alkylamino-3-chloro-5,6-dicyanopyrazine 2 in the presence of tributylamine in N,N-dimethylformamide (DMF) gave 5,10-disubstituted-2,3,7,8-tetracyano -5,10-dihydrodipyrazino〔2,3-b:2',3'-e]pyrazines 3, which showed strong mesomorphic property and were anticipated as new chromophoric system for functional dye materials. Absorption spectra, fluorescent properties and other physical properties were correlated with their chemical structures. Vanadyl oligomeric porphyrazine with long alkyl groups synthesized from 3 had satisfactory solubility in tetrahydrofuran (THF), diethyl ether and dimethylsulfoxide (DMSO). The syntheses and characterization of vanadyl polymeric porphyrazines derived from 3 with long alkyl groups are reported.

• Fibers and Polymers
• /
• 제1권2호
• /
• pp.111-115
• /
• 2000

The effects of nitrile group substitution onto aromatic polyamide backbone on the gas permeability and permselectivity of the polymers are examined. The gas permeability of aromatic polyamides increase with increasing the content of nitrile group substitution, whereas the permselectivity decreases with increasing the nitrile group contents. The effects of chain linrearity on the permeability and permselectivity are also examined. The non-linearity of the polymers increases the permeability. These behaviors are interpreted in terms of chain packing and crystallinity of the aromatic polyamides.

• Journal of the Korean Society of Food Science and Nutrition
• /
• 제27권2호
• /
• pp.305-312
• /
• 1998

Normal tensile strength in collagen fibrils is due to intermolecular and intramolecular crosslinks which are known to be altered in aging. Pyridinoline, a mature crosslink which is stable and nonreducible, is derived from two hydroxyallysine and one hydroxylysine residues of collagen fibrils. The excess formation of pyridinoline in collagen is associated with making the tissue stiffer, less soluble and less digestible by enzymes. Lysyl oxidase is the enzyme that initiates the biosynthesis or crosslinks in collagen by catalyzing the oxidative deamination of the lysyl and hydroxylysyl residues in these molecules, and its activity is inhibited by $\beta$-aminopropionitrile(BAPN). Our previous work demonstrated that the pyridinoline content of bone collagen significantly was increased during incubation for 5 weeks at 37$^{\circ}C$ invitro, but it was diecrased by the addition of ascorbic acdi(AsA). In this study, we clarified the specific action of AsA in aging process in vitro enzymatic reaction.

• Journal of the Korean Society of Food Science and Nutrition
• /
• 제23권2호
• /
• pp.358-370
• /
• 1994

Plant cell walls consist of a variety of chemical constituents such as cellulose, humicelluloses, pertins, lignin, glycoproteins, etc. These components are strongly linked through hydrogen , covalent, ionic and hydrophobic bondings, which thus confers the self-protection capability on plants. Some processing by-products (hulls, brans, pomaces) of cereal, fruits and vegetables are very limited in further utilization due to their compact structural rigidity. In view of the fact that the plant cell walls are essentially composed of dietary fiber components , solubilization of the strong intermolecular linkage s can contribute to increasing the soluble dietary fiber content and thus diversifying the functional and physiological role of plant cell walls as dietary fiber sources. This article reviews the chemical constituents of cereals, fruits & vegetables and brown seaweeds with reference to their intermoleuclar linkages. An particular emphasis will be placed on the solubilizing phenomena of rigid plant cell walls by extrusion and the resulting change of functional properties. It is suggested that underutilized food resources, typically exemplified by various food processing by-products and surplus seaweeds, can be successfully modified toward improved functional performance by extrusion.