Researches on the Stability of Porphyra-334 Solution and Its Influence Factors

The stability of porphyra-334 in solutions of different pH values at different temperatures was studied. In high acidic conditions, below pH 3, the absorption maximum, λ max, of porphyra-334 shows hypsochromic shift towards lower wavelength and the absorbance also has a light decrease. In high alkaline conditions of over pH 12, the absorbance of porphyra-334 decreases and an unknown compound with a peak maximum at 225 nm appears. The peak height of the unknown compound increases with the decrease of absorbance of porphyra-334. This might be related to the decomposition of porphyra-334. At room temperature, porphyra-334 solutions, except high alkaline solutions, are stable. Increasing the temperature, especially higher than 60℃, promotes the decomposition of porphyra-334 and causes the absorbance decrease both in basic and acidic solutions.

Protective Effect of Topically Applied Polypeptide from Chlamys farreri Against Ultraviolet Radiation-Induced Chronic Skin Damage in Guinea Pig

Polypeptide from Chlamys farreri (PCF) , a topical polypeptide isolated from Chlamys farreri , was used in this experiment aimed to investigate the photoprotective effect of PCF against chronic skin damage induced by ultraviolet A (UVA) and ultraviolet B (UVB) radiation. The chronic ultraviolet irradiated guinea pig model was established, and visible changes in the skin including wrinkling, sagging and erythema were observed. Malondialdehyde (MDA) and antioxidant enzymes including superoxide dismutase (SOD) and glutathione peroxidase (GSH px) in the dorsal skin were determined using biochemical methods. The results showed:(1)PCF (5 % and 20%) could greatly protect the dorsal skin of guinea pig against wrinkling, sagging and erythema induced by UV radiation in a concentration dependent manner.(2)PCF could reduce MDA formation in the dorsal skin caused by UV irradiation, while increasing the activities of SOD and GSH px.(3)The differences among the PCF groups and UV model group were significant ( P <0.05, P <0.01). These results indicated that topical application of PCF provided broad solar UV spectrum photoprotection; and that the antioxidant property of PCF might play a role in photoprotection.

Short-Wave Emission and Microdischarges during Self-Propagating High-Temperature Synthesis

Emission in the X-ray and ultraviolet （200-300 nanometers） region of spectrum is found out during combustion of heterogeneous systems with the formation of condensed products, and pulses from microwave emission with short duration are recorded as well. Combustion of a Ti-B powder system showed that self-propagating high-temperature synthesis （SHS） is accompanied by two types of X-ray radiation. Radiation of the first type has the maximum quantum energy - 5 keV. It is supposed that this type is caused by micro-breakdowns due to the charge separation in combustion products. Runaway electrons and soft X-ray radiation are generated due to the concentration of electric field on microparticles during breakdown. Radiation of the second type has the quantum energy up to - 15 keV. It is supposed that it is caused by exoemission of photons. UV radiation in the region of 200-300 nm is recorded during SHS in different gases （He, Ar, N2）. This radiation is shown to have the highest intensity in helium at the pressure - 25 x 103 Pa.