HD Content Research Articles

IDENTIFICATION AND DETERMINATION OF THE ACTIVE COMPOUNDS IN GASTRODIA ELATA BLUME BY HPLC

A simple, sensitive, and specific high-performance liquid chromatography method has been developed for the simultaneous quantification of the three major biologically active ingredients, gastrodin (GA), 4-hydroxybenzyl alcohol (HA), and 4-hydroxybenzaldehyde (HD), in Gastrodia elata Blume for the first time. The HPLC assay was performed on a reversed phase ODS column by using methanol-water-isopropyl alcohol (35:55:10, v:v:v) as mobile phase with a flow rate of 0.4mL/min. The detection wavelength was set at 270 nm. Regression equations revealed linear relationships (correlation coefficients: 0.9997–0.9999) between the peak area of each constituent (GA, HA, HD) and its concentration. The relative standard deviations of the retention times of three constituents range between 0.2∼0.5%. The recoveries for the three constituents ranged between 96.6∼98.5%. The GA, HA, HD contents measured 12.0 mg/g (2.53% RSD), 2.1 mg/g (2.04% RSD), and 0.13 mg/g (2.63% RSD), respectively, in the ethanol extracts of Gastrodia elata Blume.

Cutaneous Uptake of 14C-Hd Vapor By The Hairless Guinea Pig

ABSTRACTThe hairless guinea pig (HGP) is used by our laboratory to model the human cutaneous response to sulfur mustard (HD), bis(2-chloroethylsulfide), exposure. We determined the HD content in the skin of HGP after a 7-min exposure to vapors saturated with a mixture of HD and l4C-HD. Concentration/time (CT) values in the range of 2 μg/cm2/min were determined by counting skin 14C disintegrations per min (dpm) in animals euthanized immediately after exposure. These values are similar to human penetration rates obtained by other investigators. A rate curve monitoring the reduction in skin 14C dpm was developed for animals euthanized between 0 and 24 hr post- exposure. This curve showed the greatest change after 1 hr. The epidermal (62%) to dermal (38%) ratio of 14C at 24 hr was measured for two animals. We saw no site preference for HD penetration among the 8 sites used. The 14C content of template adhesive tape was determined to follow HD distribution. These results contribute to a better understanding of the cutaneous response to HD in the HGP model.

Modeling of nickel surface state in electrocatalytic hypophosphite oxidation according to on‐line electrochemical mass spectrometry studies

AbstractComputer simulation of possible distributions of Had and Dad atoms developed on nickel surface as a result of partial reactions of anodic hypophosphite oxidation and cathodic proton (deuteron) discharge from water respectively was used for modeling of the catalyst surface state according to on‐line electrochemical mass spectrometry data. The simpliest lattice‐gas model gives a probable qualitative description of the catalyst surface state and allows the genesis of electrocatalytic properties of nickel with the electrode potential to be followed. Location of anodic and cathodic half‐reactions at special types of sites was evidenced, leading to formation of non‐equilibrium H2, HD and D2 mixtures with the lower HD content than that predicted theoretically.

Sequence distribution and thermal behaviour of poly(ethylene 2,6-naphthalate-co-hexamethylene 2,6-naphthalate) copolyesters

Binary copolymers of poly(ethylene 2,6-naphthalate) (PEN) and poly(hexamethylene 2,6-naphthalate) (PHN) were synthesized and their sequence distributions were investigated over the entire range of copolymer composition by 13C nuclear magnetic resonance spectroscopy. The melting temperatures of these copolymers were depressed gradually with the increase of 1,6-hexanediol (HD) in the composition and eutectic behaviour appeared which depended only on the sequence propagation probability P, not directly on the composition, and showed a minimum at about 60 mol% HD content at which the average sequence length is the shortest. The copolymers rich in ethylene units formed only PEN crystals with complete rejection of the hexamethylene units. Also, the copolymers rich in hexamethylene units formed only PHN crystals excluding ethylene units.

Effect of Hexadiene and Vinyl Acetate on the Flow Behaviour of EPDM and EVA Blends

Abstract Flow behaviour of melt-mixed blends of EPDM and EVA with special reference to the change of their HD and VA content are studied. Viscosity decreases linearly with the increase in shear rate for all the blends which is more prominent in case of low VA content EVA. Low HD shows more pseudoplastic behavior. Stored elastic energy increases as the EPDM/EVA ratio decreases. Relaxation time increases for high HD and VA content. Circumferential wrinkles on the extrudate surface with surface fractures was observed at high shear rate for high HD containing EPDM.

Crystal-chemistry and cation ordering in the system diopside-jadeite: A detailed study by crystal structure refinement

The Nybo eclogite pod in Norway is characterized by a great variety of clinopyroxene compositions with Jd contents ranging from less than 5% up to nearly 80%, whilst Ac+Hd contents remain almost constant (mostly within 10±5%). Unconstrained X-ray structure refinement has been carried out on 16 pyroxene crystals (8 with C2/c and 8 with P2/n space group) from the Nybo eclogite, and also on one omphacite crystal (from Lago Mucrone in the Sesia-Lanzo Zone, Western Alps) which displays the highest degree of cation ordering yet described. The final discrepancy factors range from 0.014 to 0.029. The population of the sites has been determined on the basis of bond length considerations and of the results of the site occupancy refinement. Six of these crystals were subsequently analysed by electron microprobe. The tetrahedral sites are occupied by Si with negligible amounts of Al. Al, Mg, Fe3+ and Fe2+ occur at the octahedral sites; in the ordered P2/n crystals Al and Fe3+ are concentrated at the M11 site, whilst Mg and Fe2+ are concentrated and the M1 site. The eight-coordinated sites contain Ca and Na with negligible amounts of Fe and/or Mg. Ordering of Ca and Na takes place in the P2/n samples in such a way that in the most ordered crystal the M2 site contains almost exactly 0.75 Na+0.25 Ca and the M21 site 0.25 Na+0.75 Ca. Some geometrical features of the tetrahedra as well as of the octahedra (e.g. tetrahedral quadratic elongation and TILT angle) are not a simple linear function of composition, even when no change in space group occurs. The crystals evidently do not behave like a binary system of the two components, Di and Jd, but behave rather as if the composition Di0.50 Jd0.50 was a distinct end member. The boundaries between disordered and ordered phases in the Nybo pyroxenes fall at about 0.35 and 0.65 Jd/(Di+ Jd), in close agreement with the previous TEM investigations. The degree of order varies with composition following a bell-shaped curve: different coaxial bell-shaped curves can be drawn for crystals which have similar compositions but come from different metamorphic environments. The order vs composition diagrams may be useful for the interpretation of the P-T-t histories of the host rocks.