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The photodissociation dynamics of small (H2O)n+ (n=2–5) clusters have been studied at 308 nm using a high resolution cryogenic cylindrical ion trap velocity map imaging spectrometer. Time-of-flight mass spectra and images of ionic photofragments are recorded. (H2O)2+ clusters dissociate to yield H3O+ and H2O+ photofragments, indicating the presence of both proton-transferred (H3O+-OH) and hemibonded (H2O-OH2)+ structures for the dimer cluster. (H2O)n+ (n=3–5) clusters prevailingly dissociate to the H+(H2O)n–2, ...,1 photofragments by losing both of OH and H2O components, and the (H2O)5+ cluster shows an additional channel to produce H+(H2O)4 by only losing OH. The former suggests the (H2O)n–2H3O+OH structures for the (H2O)n+ (n=3–5) clusters, while the latter suggests in (H2O)5+ that, the H3O+ core and OH are separated by H2O. The results elucidate the structure progresses of small (H2O)n+ clusters. The experimental images yield negative and small values for the anisotropy parameters of photofragments, indicating that (H2O)n+ (n=2–5) clusters undergo vertical electronic transitions upon photon absorption followed by slow dissociation, and lead to highly internally excited photofragments. [ABSTRACT FROM AUTHOR]

Currently, Epimedium Sagittatum is the mainstream Epimedium present in the market of China. It has the functions of tonifying kidney Yang, strengthening muscles and bones, and removing wind and dampness. It is mainly used in clinical practice to tonify kidney and strengthen Yang, which is one of the most potential and key Chinese medicines. At present, the lack of unified standards for cultivation, harvesting and processing of Epimedium has resulted in a wide variety of quality differences in the market. Based on literature review, this paper reviews the quality status of Epimedium, and summarizes the influences on quality control of Epimedium from six aspects, including variety, place of origin, cultivation, harvest time, harvest site and processing method. In order to improve the overall quality of Epimedium, it is suggested that systematic research should be conducted on planting, harvesting, processing and storage of Epimedium, and unified cultivation technical regulations should be formulated to meet the good agricultural practice in planting specifications. [ABSTRACT FROM AUTHOR]

The objective of the current study was to compare, the wood properties of different Chinese wood verities to provide information for the rational use of wood and the directional cultivation of high quality wood. For this purpose a total of 7 excellent clones of 30-years old Chinese fir wood that were 79172, 8219, 7962, 79182, 79173, 7922, and 7911, respectively were taken to compare with one control (CK) wood collected from Jindong Forest Farm in Hunan Province. The air-dry density, basic density, modulus of rupture (MOR), modulus of elasticity, compressive strength parallel to grain, tensile strength parallel to grain, compression resistance of all stripes to flat & radial and compression resistance of local to flat & radial were measured according to national standards. Air-dry density, basic density, chord-wise cross-grain compression, all radial cross-grain compression, chord cross-grain local compression, radial cross-grain local compression, along-grain bending strength, alonggrain resistance The measured values of flexural modulus, compressive strength along the grain, and tensile strength along the grain are 0.376-0.438 g/cm3, 0.301-0.355 g/cm3,5.18-7.16Mpa, 4.64-6.27Mpa, 9.68-10.99MPa, 9.18-10.66MPa, 64.34-79.38 Mpa, 7.78-8.95Mpa, 42.78-50.20MPa, 93.72-114.69 MPa; the corresponding maximum values are 79173 (0.463 g/cm3),79182 (0.355 g/cm3),79172 (7.16Mpa),79172 (6.27 Mpa),7922 (10.99MPa),79172 (10.66 MPa),79182 (179.38 Mpa),79182 (8.95 Mpa), 79172 (50.20 MPa), 79172 (114.69 MPa). In the physical and mechanical properties of wood, the air-dry density, basic density, chordwise transverse grains are all compressive, radial transverse grains are all compressive, chord transverse grains are locally compressive, radial transverse grains are locally compressive, and along grains of flexural strength, along-grain flexural modulus, along-grain compression and along-grain tensile are significantly different among different strains and are closely related. Using 10 indicators of wood physical and mechanical properties for cluster analysis, the wood properties of 79172 and 7922 are generally better than other varieties. [ABSTRACT FROM AUTHOR]

We present an experimental study on the photodissociation dynamics of [O 2 -H 2 O] + in the 580-266 nm wavelength range using a cryogenic ion trap velocity map imaging spectrometer. The cryogenic ion trap produces mass selected and internally cold [ O 2 - H 2 O ] + ions for photodissociation. By detecting both the O 2 + and H 2 O + photofragments using the time-of-flight mass spectrometry and velocity map imaging techniques, branching ratios and total kinetic energy release distributions of the O 2 + + H 2 O and H 2 O + + O 2 product channels are experimentally measured at 16 different excitation energies. State-resolved photodissociation mechanisms of the parent [O 2 -H 2 O] + are interpreted as (1) the O 2 (X 3 Σ g - ) + H 2 O + ( X ~ 2 B 1 ) , O 2 (a 1 Δ g ) + H 2 O + ( X ~ 2 B 1 ) , and O 2 (X 3 Σ g - ) + H 2 O + ( A ~ 2 A 1 ) channels are produced from direct dissociation of [O 2 -H 2 O] + in its excited B ~ 2 A ″ , D ~ 2 A ″ , and F ~ 2 A ″ states, respectively; (2) the O 2 + (X 2 Π g ) + H 2 O ( X ~ A 1 1 ) channel is produced from nonadiabatic relaxations of the excited B ~ 2 A ″ , D ~ 2 A ″ , and F ~ 2 A ″ states to the X ~ 2 A ″ ground state with subsequent dissociation. The latter nonadiabatic processes involve charge-transfer on the potential energy surfaces, and the charge-transfer probabilities are determined from experimental results. The dissociation energy of the ground state to the lowest dissociation limit is experimentally refined as D 0 = 1.05 ± 0.05 eV. This work provides important information to understand the charge-transfer dynamics in the photochemistry of [O 2 -H 2 O] + and in the ion-molecule reaction O 2 + H 2 O + → O 2 + + H 2 O.