• Journal of Powder Materials
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• v.18 no.2
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• pp.176-180
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• 2011

Study of the main properties of PVDF films produced by two processing technologies such as hot pressing from a melt or solution casting was the aim of this paper. All samples were prepared of as-received PVDF powder. First group of samples was prepared by the hot pressing. Second group of samples was prepared by the solution casting method. PVDF powder was dissolved in dimethylformamide. To characterize properties of samples, different experimental methods such as FRA (dielectric spectroscopy), IR-spectroscopy and DSC/TGA analysis were used in this work. It was found that IR-spectra of both studied groups do not change compared to that for virgin PVDF powder. It confirms that molecular structure is practically independent on the processing technology of samples. The only difference has been found that new band centered at $1723\;cm^{-1}$ appears for samples prepared by the hot pressing method. This absorption band is related with formation of C=C bonds in samples prepared by the hot pressing method in contrast both to PVDF powder and samples prepared by the solution casting method.

• Journal of Applied Biological Chemistry
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• v.43 no.1
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• pp.37-43
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• 2000

1,3,2-Dioxaphosphorinanes are suitable compounds for studying the stereochemistry of substitution at phosphorus. Cis- and trans-5-hydroxymethl-5-methyl-2-thiono-2ethoxy-1,3,2-dioxaphosphorinane were prepared, and their structures and stereochemistry unambiguously assigned by NMR and X-ray crystallography with acetoxy and 3,5-dinitrobenzoyloxy derivatives, respectively. Trans isomer gave $^{31}P$ NMR signal at higher field than cis isomer, and the ring proton Spectrum of cis isomer showed characteristic pattern for identifying its geometry. In X-ray crystallography they adopted a chair conformation with the ethoxy groups in the axial positions, and the sulfide groups in the equatorial positions. A flattening of the ring around the phosphorus center was noted, the POC bond angles were about $120^{\circ}$, and the C-O bonds in the ring were significantly longer than the C-O bond for the ethoxy group or the C-O bond for hydroxyl group.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.5
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• pp.721-733
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• 2019

Objective: The objectives of this study were to investigate the thermal gelation properties and molecular forces of actomyosin extracted from two classes of chicken breast meat qualities (normal and pale, soft and exudative [PSE]-like) during heating process to further improve the understanding of the variations of functional properties between normal and PSE-like chicken breast meat. Methods: Actomyosin was extracted from normal and PSE-like chicken breast meat and the gel strength, water-holding capacity (WHC), protein loss, particle size and distribution, dynamic rheology and protein thermal stability were determined, then turbidity, active sulfhydryl group contents, hydrophobicity and molecular forces during thermal-induced gelling formation were comparatively studied. Results: Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed that protein profiles of actomyosin extracted from normal and PSE-like meat were not significantly different (p>0.05). Compared with normal actomyosin, PSE-like actomyosin had lower gel strength, WHC, particle size, less protein content involved in thermal gelation forming (p<0.05), and reduced onset temperature ($T_o$), thermal transition temperature ($T_d$), storage modulus (G') and loss modulus (G"). The turbidity, reactive sulfhydryl group of PSE-like actomyosin were higher when heated from $40^{\circ}C$ to $60^{\circ}C$. Further heating to $80^{\circ}C$ had lower transition from reactive sulfhydryl group into a disulfide bond and surface hydrophobicity. Molecular forces showed that hydrophobic interaction was the main force for heat-induced gel formation while both ionic and hydrogen bonds were different significantly between normal and PSE-like actomyosin (p<0.05). Conclusion: These changes in chemical groups and inter-molecular bonds affected protein-protein interaction and protein-water interaction and contributed to the inferior thermal gelation properties of PSE-like meat.

• Journal of Microbiology and Biotechnology
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• v.8 no.2
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• pp.158-164
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• 1998

Crystal structural analyses of the API-TLCK complex revealed that the ${\epsilon}$-amino group (NZ) of the lysyl part of TLCK forms hydrogen bonds with OD1 of $Asp^225$ which is a substrate specificity determinant of API, OG of $Ser^214$, O of $Ser^214$, OG1 of $Thr^189$, and O of $Thr^189$ l89/. The ${\beta}$-carboxyl oxygen of $Asp^225$ forms hydrogen bonds with the NE1 of $Trp^182$. From these observations, it is thought that besides $Asp^225$, $Thr^189$, $Ser^214$, and $Trp^182$ may also contribute to the steric specificity for lysine and high proteolytic activity of API. The side-chain hydroxyl groups of $Thr^189$ and $Ser^214$ were removed to elucidate the role of these hydrogen bonds in the $S_1$-pocket. The $k_{cat}$/$K_m$ of T189V, S214A, and T189V.S214A were decreased to 1/4, 1/3, and 1/46, respectively, of the value for native API. The decreased activities were mainly due to the increase of $K_m$. The CD and fluoroscence spectra of the three mutants were similar to those of wild-type API. With regards to the kinetic parameters ($K_i\;and\;k_2$) of mutants for the reaction involving TLCK and DFP, $k_2$decreased by increase of $K_1$ only. These results suggest that the decreased catalytic activity of these mutants is caused by the partial loss of the hydrogen bond network in the $S_1$-pocket. On the other hand, the similarity of enzymatic properties between W182F and the native enzyme suggests that the hydrogen bond between OD2 of $Asp^225$ and NE1 of $Trp^182$ is not directly related to the reaction of $Asp^225$ with the substrate.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.5
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• pp.622-627
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• 1994

The purpose of this study is to investigate the adsorption rate, adsorption quantities and the UV-Cut effects of cotton fabrics treated with several UV absorbents. The result of this study were as follows: cotton fabric treated with 2,2'-dihydroxy-4- methoxy-benzophenone shows more efficient than ones treated with 4-aminobenzoic acid and 2·hydroxy-1, 4-naphthoquinone in UV absorption. This may be due to the absorption of UV light by formation of intra moleculaar hydrogen bond. The formation of hydrogen bonds between hydrogen atoms of two hydroxy groups and one oxygen atom of carboxyl group in 2, 2'-dihydroxy-4-methoxy-benzophenone would be easier than that of the other absorbents. The adsorption isotherms of 4-aminobenzoic acid and 2-hydroxy-1, 4-naphthoquinone were similar to Freundlich type, while that of 2, 2'-Dihydroxy-4-methoxy-benzophenone was Henry type. Cotton fabrics treated with Antifade MC-100 and W Cut I-2 were just alike in UV absorption, but Antifade 8001 was inferior to the others.

• Bulletin of the Korean Chemical Society
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• v.5 no.4
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• pp.158-162
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• 1984

The crystal structure of chloramphenicol base, $C_9H_{l2}N_2O_4$, the deacylated base of antibiotic chloramphenicol, has been determined by X-ray diffraction techniques using diffractometer data obtained by the ${\omega}-2{\theta}$ scan technique with CuK${\alpha}$ radiation from a crystal with space group symmetry $P2_12_12_1$ and unit cell parameters a = 22.322(6), b = 7.535(6), c = 5.781(5) ${\AA}$. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.051 for the 573 observed reflections. The overall conformation of the base is quite different from those of the chloramphenicol congeners which are similar despite the presence of many rotatable single bonds. The propane chain in the base is bent with respect to the phenyl ring, while it is extended in the chloramphenicol congeners. There is no intramolecular hydrogen bond between the hydroxyl groups of the propanediol moiety. All of the molecules in the crystal lattice are connected by a three-dimensional hydrogen bonding network.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.312-315
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• 2018

Although the reversibility of 10,12-pentacosadiynoic amino meta-acid(PCDA-mBzA) against temperature and pH was reported, the modulation of reversibility by ion adsorption at terminal functional group has not been investigated. In this work, we developed a simple method for modulating the reversibility of PCDA-mBzA films upon a thermal stimulus by cadmium ion adsorption inducing the breakage of the outer hydrogen bonding of two hydrogen bonds, which are responsible for the reversible properties of PCDA-mBzA. External reflection-Fourier transform infrared (ER-FTIR) analyses revealed that the hydrogen bonding between the carboxylic acid groups was broken through ion adsorption and only a single hydrogen bond between the amide groups remained in the PCDA-mBzA polymer. In addition, PCDA-mBzA films could recover their original property through cadmium ion desorption. These results present that the transition between reversibility and irreversibility can be modulated artificially simply through the adsorption and desorption of metal ions.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2454-2458
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• 2007

Exploring the basic concepts for the design of CO2-philic molecules is important due to the possibility for “green” chemistry in supercritical CO2 as substitute solvent systems. The Lewis acid-base interactions and C?H…O weak hydrogen bonding were suggested as two key factors for the solubility of CO2-philic molecules. We have performed high level quantum mechanical calculations for the van der Waals complexes of CO2 with trimethylphosphate and trimethylphosphine oxide, which have long been used for metal extractants in supercritical CO2 fluid. Structures and energies were calculated using the MP2/6-31+G(d) and recently developed multilevel methods. These studies indicate that the Lewis acid-base interactions have larger impact on the stability of structure than the C?H…O weak hydrogen bonding. The weak hydrogen bonds in trimethylphosphine oxide have an important role to the large supercritical CO2 solubility when a metal is bound to the oxygen atom of the P=O group. Trimethylphosphate has many Lewis acid-base interaction sites so that it can be dissolved into supercritical CO2 easily even when it has metal ion on the oxygen atom of the P=O group, which is indispensable for a good extractant.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.1
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• pp.15-22
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• 1994

The formation of carbonyl group was dominant to other functional groups. Concentrations of both carboxyl and peroxide groups were found to rapidly reach low steady state values that increased slightly with increa-sing temperature and relatice humidity. Since the deg-radation of cellulose samples was in the initial stage and the conversion of glycosidic bonds and hydroxyl groups were very small, it was found that changes in the physical and chemical properties could be fitted to a first-order reaction model.

• Archives of Pharmacal Research
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• v.7 no.2
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• pp.115-120
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• 1984

The crystals of bromhexine-HCl, $C_{14}$ H$_{21}$ N$_{2}$Br$_{2}$Cl, are orthohombic, space group Pca2 with a = 14.598(2)A, b=12.461(3)A, c =9 9.186(1) A and Z = 4. Intensity dat for 967 reflections (Fobs > 6.sigma.(F)) were collected on a Rigaku-Denki automatic four circle diffractometer. The structure was solved by the Patterson and Fourier methods. Refinements were carried out to the final R value of 0.082. The cyclohexane ring has a normal chair form and the benzene ring is planar. There are three independenet hydrogen bounds in the structure. One is an intermolecular hydrogen bond (N-H... Cl) and the others are intramolecular hydrogen bonds (N-H...Br, N$^{+}$-H...Cl$^{[-10]}$ ) Apart from the hydrogen bounding system the molecules are held together in the crystal by van der Waals force.e.