Structural differences between light and heavy rare earth element binding chlorophylls in naturally grown fern: Dicranopteris linearis.

Chloroplasts and chlorophylls were isolated from the leaves of Dicranopteris linearis, a natural perennial fern sampled at rare earth element (REE) mining areas in the South-Jiangxi region (southern China). The inductively coupled plasma-mass spectrometry (ICP-MS) results indicated that REEs were present in the chloroplasts and chlorophylls of D. linearis. The in vivo coordination environment of light REE (lanthanum) or heavy REE (yttrium) ions in D. linearis chlorophyll-a was determined by the extended X-ray absorption fine structure (EXAFS). Results revealed that there were eight nitrogen atoms in the first coordination shell of the lanthanum atom, whereas there were four nitrogen atoms in the first coordination shell of yttrium. It was postulated that the lanthanum-chlorophyll-a complex might have a double-layer sandwich-like structure, but yttrium-binding chlorophyll-a might be in a single-layer form. Because the content of REE-binding chlorophylls in D. linearis chlorophylls was very low, it is impossible to obtain structural characteristics of REE-binding chlorophylls by direct analysis of the Fourier transform infrared (FTIR) and ultraviolet (UV)-visible spectra of D. linearis chlorophylls. In order to acquire more structural information of REE-binding chlorophyll-a in D. linearis, lanthanum - and yttrium-chlorophyll-a complexes were in vitro synthesized in acetone solution. Element analyses and EXAFS results indicated that REE ions (lanthanum or yttrium) of REE-chlorophyll-a possessed the same coordination environment whether in vivo or in vitro. The FTIR spectra of the REE-chlorophyll-a complexes indicated that REEs were bound to the porphyrin rings of chlorophylls. UV-visible results showed that the intensity ratios of Soret to the Q-band of REE-chlorophyll-a complexes were higher than those of standard chlorophyll-a and pheophytin-a, indicating that REE-chlorophyll-a might have a much stronger ability to absorb the ultraviolet light. The MCD spectrum in the Soret band region of lanthanum-chlorophyll-a showed a special peak, but yttrium-chlorophyll-a did not have this special peak, corresponding well to their double-layer and single-layer structure, respectively.

[Effects of varying the opaque thickness and the type of metal ceramic alloy on color].

OBJECTIVE: To compare the color differences of different metal bases and different opaque thickness, and evaluate the best thickness of opaque on different metal bases. METHODS: Precious metal, gold sediment and Ni-Cr plates were prepared as bases, then opaque samples of 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5 mm thickness were fabricated on such plates. Minolta chromatics meter CR-321 was used to examine the color properties of these samples, and deltaE was calculated to evaluate the color difference of the specimens. RESULTS: For the restoration based on Ni-Cr and precious alloys, the color of restorations was not affected by the color of metal bases as the thickness of opaque reached 0.3 mm, and the chromatic value deltaE < 1.5 NBS. For the restoration based on gold sediment, the color of restoration was not affected by the color of metal as the thickness of opaque reached 0.1 mm, and the chromatic value deltaE < 1.5 NBS. CONCLUSION: Different opaque thickness was necessary to obtain ideal color appearance in clinic. As the opaque thickness increased, the color of restoration based on Ni-Cr and noble metal increased but the color of restoration based on gold sediment decreased.

Effects of spraying rare earths on contents of rare Earth elements and effective components in tea.

Rare earth (RE) fertilizer is widely applied in China to increase the yield and the quality of crops including tea. However, the effects of spraying RE fertilizer on the contents of rare earth elements (REE) and effective components in tea are unknown. The results from basin and field experiments show that the values of the REE concentrations in new shoots of tea plants and the concentration of REE in the soil (REE/REEs) either from control basins or from treatment basins were smaller than those in other parts of tea plant and similar between control and treatment. The longer the interval between spraying RE fertilizer and picking the shoots of tea plants, the less the effects from spraying. About 80% summation operator REE (the sum of the concentrations of 15 REE) in tea, whether it came from spraying or not, was insoluble in the infusion. About 10% the soluble REE of summation operator REE in tea infusion was bound to polysaccharide, and the amount of REE bound polysaccharide decreased over time. At least a 25 day safety interval is needed between spraying and picking if the microelement fertilizer is used, in order to enhance tea output and to ensure tea safety.

Mechanism of lanthanum effect on chlorophyll of spinach.

The mechanism of La(3+) effect on chlorophyll (chl) of spinach in solution culture has been studied. The results show that La(3+) can obviously promote growth, increase chlorophyll contents and photosynthetic rate of spinach. La(3+) may substitute Mg(2+) for chlorophyll formation of spinach when there is no Mg(2+) in solution. La(3+) improves significantly PSII formation and enhances electron transport rate of PSII. By ICP-MS and atom absorption spectroscopy methods, it has been revealed that rare earth elements (REEs) can enter chloroplasts and increase Mg(2+)-chl contents; and REEs bind to chlorophyll and also form REE-chl. REE-chl is about 72% in total chlorophyll with La(3+) treatment and without Mg(2+)in solution. By UV-Vis, FT-IR and extended X-ray absorption fine structure spectroscopy (EXAFS) methods, it has been found that La(3+) coordinates with nitrogen of porphyrin rings with the average La-N bond length of 0.253 nm.

[The separation of overlapping peaks of lanthanide complex by photoacoustic phase-resolved method].

Photoacoustic(PA) phase-resolved method is used to separate the overlapping peaks of lanthanide complex for the first time. PA peaks of Nd3+ are covered completely by the PA absorption of tryptophan(Trp) for Nd(Trp)3Cl3.H2O within 300-400 nm. The patterns of PA phase spectrum depend on the ligand and lanthanide ion, and the phase angles are associated with the lifetime of the excited states and the optical absorption coefficient. Different phase angles of the ligand and lanthanide ion bring the possibility to separate their overlapping peaks by PA phase-resolved method. The phase angle of Trp(106 degrees) is calculated according to the in-phase and out-of-phase signals. In the PA amplitude spectrum, only the contribution of Nd3+ can be observed when the phase angle varies 90 degrees. PA peaks of Nd(Trp)3Cl3.H2O are separated well and assigned. PA phase-resolved method has the advantage to interpreted the spectrum based on different phase angles, and is free from the overlapping of different absorption bands.

Components and activity of polysaccharides from coarse tea.

Coarse tea contained a high content of polysaccharide complex. Composed of polysaccharide and protein, the polysaccharide complex from tea (TPS) belonged to glycoprotein with the molecular weight () of (10.7-11.0) x 10(4). When mice (7 weeks old, C57BL/8) were injected with TPS, the levels of blood glucose (BG) in normal mice and model mice with high BG were decreased significantly by averages of 13.54 and 22.18%, respectively. The antibody concentration (OD(413 nm)) in the mice injected with 2.4 mg/mL TPS was increased evidently by 44.93% (p < 0.01). TPS treatment was beneficial not only for the subsequent production of interleukin (IL) 2 in spleen cells of adjuvant arthritis (AA) rats but also because it prohibited the body from producing too much IL-1 in AA rats. Treatment of diabetes with coarse tea in both China and Japan may be related to TPS and the content of TPS in coarse tea.