Debate continues in theoretical ecology over whether and why the scaling exponent of biomass -density (M -N ) relationship varies along environmental gradients. By developing a novel geometric model with assumptions of allometric growth at the individual level and open canopy at the stand level, we propose that plant height-crown radius and canopy coveragedensity relationships determine the above-ground M-N relationship in stressful environments. Results from field investigation along an aridity gradient (from eastern to western China) confirmed our model prediction and showed that the aboveground M-N scaling exponent increased with drought stress. Therefore, the 'universal' scaling exponents (23/2 or 24/3) of the M-N relationship predicted by previous models may not hold for above-ground parts in stressful environments.

Quantifying the self-thinning process in various plant communities has been a long-standing issue in both theoretical and empirical studies. Most studies on plant self-thinning have centered only on aboveground parts, and rarely on belowground parts. There is still a general lack of comparison between above-and belowground self-thinning processes, especially for forest communities. The fundamental mechanistic difference and the functional association between above-and belowground competition indicate that the self-thinning process of belowground parts may be different from that of aboveground parts. We investigated the self-thinning lines for above-ground (M A ), below-ground (M B ), and total biomass (M T ), respectively, across forest communities in China. The results showed that neither the classical self-thinning rule (À3/2 exponent) nor the universal scaling rule (À4/3 exponent) can apply to all the self-thinning relationships across these forest communities and that the self-thinning lines for belowground biomass were flatter and lower than those for aboveground biomass across most of these forest communities.

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Terbium(III), as a good luminescent probe, was developed for the study of the interaction between paraquat and calf thymus DNA (ctDNA) when the binding mode of small molecules to DNA was electrostatic binding. This interaction was further investigated using an ethidium bromide (EB) probe, UV absorption spectra, and circular dichroism spectra. On the basis of Scatchard plots constructed from fluorescence titration data of the ctDNA-Tb(3+) system in the presence of paraquat, the binding constants between paraquat and ctDNA were obtained. The results showed that the electrostatic attraction between positively charged sodium ion and negatively charged phosphate groups could inhibit the binding of paraquat to ctDNA, and competitive inhibition between Tb(3+) and paraquat also existed when they were bound to ctDNA. The effects of paraquat on the fluorescence intensity of the EB-ctDNA system indicated that the intercalation binding of paraquat to ctDNA could be excluded. This conclusion could be further supported by both the absorption spectra of paraquat in the presence of ctDNA and the CD spectra of the paraquat-ctDNA system.

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Defining and quantifying biomass–density relationships in dense plant stands has been a long‐standing issue in both theoretical and empirical studies. Most existing/traditional studies focus on whole plant individuals, without considering different plant components (e.g., stem, branch and leaf). However, the analysis of biomass–density relationships for different plant parts is linked to those for whole plants, and thus important for understanding plant strategies for utilizing resources and community dynamics. In our study, we investigated standing stem (MS), branch (MB) and leaf (ML) biomass–density relationships, across a range of forest communities in China. The results showed that there was no constant predicted value (e.g., −1/2 or −1/3 for MS; −1/2, −1/3 or 0 for MB and ML) that can describe all the relationships, and that the scaling exponents for stem, branch and leaf biomass varied across different forest types. In particular, standing leaf biomass (leaf biomass per unit area) was not constant in these forest communities. Furthermore, stem biomass–density lines were steeper than corresponding branch and leaf lines across most of these forest communities.

Although tPSA significantly correlated with PV in Chinese men with biopsy-proven BPH, the correlation between fPSA and PV was much stronger, and fPSA performed significantly better than tPSA at predicting thresholds of PV. fPSA may be used to estimate PV and could be a useful tool in making therapeutic decisions in Chinese men with BPH.

PSAD was a better predictor of prostate cancer in Chinese men with PSA levels of 4-10 ng/mL, especially those who have had prior ultrasound-determined measurements of prostate volume. Our data suggest that different PSAD cutoffs may need to be defined for Chinese.