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The main contribution of semiconductor nanomaterials to surface-enhanced Raman scattering (SERS) comes from charge transfer (CT) between the absorbing molecules and the semiconductor. However, it is still challenging to realize the combined effects of the electromagnetic mechanism (EM) and the chemical mechanism (CM) for semiconductor-based SERS substrates. Herein, we demonstrate and design double-shelled ZnO (ZnO-DS) hollow microspheres by a modified hydrothermal/solvothermal process. SERS experiments and theoretical simulations proved that the excellent SERS activity is mainly attributed to the combined effect of Mie resonances generated by the nanocavities in the unique hollow double-shell nanoparticles and the CT effect excited by special structure ZnO. Particularly, the produced ZnO-DS SERS substrates exhibited a low limit of detection (LOD, 1 × 10–7 M for 4-MPY), outstanding sensitivity (EF = 1.2 × 104), and high stability (RSD = 10.4%, over 30 days of storage at room temperature). Furthermore, benefiting from the matching of energy levels of the ZnO-DS substrate and probe molecules, the sulfhydryl molecules with similar structures could be selectively distinguished in complex environments. We visualize that this work will resolve the current dilemma between sensitivity and selective detection of SERS substrates and expect to enable the monitoring of target molecules in the environment containing complex mixtures such as food safety and environmental protection. [ABSTRACT FROM AUTHOR]

Coarse woody debris (CWD) has an important role in hydrological function and water and soil conservation function of forest ecosystem especially mountain forest ecosystem. To understand water holding capacity of CWD in subalpine forest of southeast Tibet, CWD reserve of primitive A. fabri forest in Sygera Mountain was investigated by sample plot method, and water absorption and storage capacity of CWD was studied by using soaking method. The results showed that decay grade was positively related to water storage potential, that is to say, the higher the decay grade, the larger the water storage potential. Saturated water holding capacity, saturated water holding rate, effective water holding capacity and effective water holding rate of A. fabri CWD aN rose with decay grade increased, and the order was V > IV > III > II > I. CWD reserve was 51. 555 t/hm2, and the maximum water storage capacity was 71. 601 t/hm2, while effective water storage capacity was 60.861 t/hm2, which was equivalent to 6.086 mm of rainfail. [ABSTRACT FROM AUTHOR]

[Objective] The paper was lo study the effects of nitrogen deposition on soil nutrients and soil dissolved organic carbon in forest-grassland landscape in Linzhi, Tibet, and to provide scientific basis and basic data for understanding and assessing the effect of atmospheric nitrogen deposition on soil nutrients and soil dissolved organic carbon. [Method] From July 2014 to August 2015, in situ nitrogen deposition (CK 0 kg • hm2/a, LN 25 kg • hm2/a, MN 50 kg • hm2/a, 1 IN 150 kg • hm2/a) was simulated in the forest-grassland boundary' of Zhuqudeng village, Bujiu Township, Linzhi County, Tibet. The soil samples were collected for analyzing nutrient and dissolved contents in the soil layer of 0-20 and 20-40 cm. The effects of different nitrogen deposition levels on soil nutrients and dissolved organic carbon (DOC) were studied. [Result] Nitrogen deposition had significant impacts on soil organic matter, total N, total P, total K, available N, available P, available K, exchangeable Ca, exchangeable Mg, pH, and DOC (P< 0.05). (2) With the deepening of nitrogen deposition from CK, LN, MN to HN in the 0-20 cm boundary soil, the contents of organic matter, total N, total P, available P, exchangeable Ca, exchangeable Mg and DOC kept decreasing, and the content of total K and available N increased continuously. The pH increased in LN treatment and decreased in HN treatment, while the available K content w'as decreased in LN and HN treatment, but increased in MN treatment. (3) The contents of organic matter, total N, total P, available N, available P, exchangeable Ca, exchangeable Mg and DOC all decreased at the soil layer of 20-40 cm under the same nitrogen deposition. The pH increased in LN treatment, but decreased in HN treatment; the content of total K decreased in LN treatment and increased in MN and HN treatments; the content of available K decreased in LN and I1N treatments, but increased in MN treatment. (4) With the deepening of boundary soil layer (0-20 lo 20-40 cm), the organic matter, total N, total P,available P, available K, exchangeable Ca, exchangeable Mg, DOC showed ihe same response to simulated nitrogen deposition, while the available N and total K responded differently. [Conclusion] Different levels of N deposition had certain impact on soil nutrient, and the variation of soil nutrients was not the same at different levels. [ABSTRACT FROM AUTHOR]

The simulated nitrogen deposition [control check (CK), 0 kg·hm²/a; low nitrogen (LN), 25 kg·hm²/a; medium nitrogen (MN), 50 kg·hm²/a; high nitrogen (HN), 150 kg·hm²/a] was performed from July 2014 to August 2015 in the forest-grassland boundary in Zhuqudeng Village, Bujiu Township, Linzhi City, Tibet Autonomous Region to analyze the activity of enzymes (invertase, catalase, urease, amylase, cellulase, polyphenol oxidase, and ß-glucosidase) in soil layers of 0-20 cm and 20-40 cm and explore the effect of different levels of nitrogen deposition on enzyme activity different layers of soil. The results showed that: ➀ different levels of simulated nitrogen deposition had remarkable effects on sucrase, amylase, cellulase, polyphenol oxidase and β-glucosidase in the soil layer of 0-20 cm (p < 0.05) and unremarkable effects on catalase and urease (p > 0.05); in the soil layer of 20-40 cm, the response made by sucrase, catalase, urease, amylase, cellulase, polyphenol oxidase and ß-glucosidase to nitrogen deposition reached a significant level (p < 0.05). ➁ In the soil layer of 0-20 cm, the activity of urease and polyphenol oxidase reduced under LN treatment and enhanced under HN treatment, and the activity of invertase, catalase, amylase, cellulose, and β-glucosidase was inhibited by nitrogen deposition. ➂ In the soil layer of 20-40 cm, the activity of polyphenol oxidase and β-glucosidase reduced under under LN treatment and enhanced under HN treatment, and the activity of invertase, catalase, urease, amylase, and cellulase was inhibited by nitrogen deposition. ➃ With the deepening of the boundary soil layer (from 0-20 cm to 20-40 cm), urease and β-glucosidase made different responses to the different levels of nitrogen deposition, while invertase, catalase, amylase, cellulose, and polyphenol oxidase showed the same response to nitrogen deposition. [ABSTRACT FROM AUTHOR]

[Objective] The research aimed to study the influence of different afforestation technology measures on soil nutrients of P. alba woodland in arid valley region of Rikaze, Tibet. It aimed to improve afforestation technology measure in arid valley region of Rikaze, Tibet, and provide theoretic basis for restoring the degraded ecosystem at upper reaches of the Yarlung Zangbo River. [Method] In arid valley region of Duojiao Village, Nanmulin County, Rikaze City, the planted land using rooting powder, egg shell, leaves, mud and water retention agent was taken as research object, while the land without any afforestation measures was taken as the control, to determine soil nutrients under different afforestation measures. [Result] Under different afforestation measures, the contents of various soil nutrients were all obviously higher than control, in which available potassium, available phosphorus, alkali hydrolysable nitrogen and organic matter in soil obviously increased than control, but there was no similar rule among different measures. [Conclusion] Vegetation restoration in dry valley belt of Rikaze by different afforestation measures is favorable for improving physical-chemical properties of soil and increasing soil fertility. [ABSTRACT FROM AUTHOR]

[Objective] The paper was to study the effects of nitrogen deposition on enzyme activity in different layers of soil. [Method] With grassland located in Zhuqudeng Village, Bujiu Township, Linzhi City, the Tibet Autonomous Region, as the object, nitrogen deposition was simulated from July 2014 to August 2015. Four N addition treatments were established: control (0 kg-hm2/a), low N (LN, 25kg-hm2/a), medium N (MN, 50 kg-hm2/a) and High N (HN, 150 kg hm2/a), aiming at measuring enzyme activity (invertase, catalase, urease, amylase, cellulase, polyphenol oxidase and fi-glucosidase) in different layers of grassland soil (0 -20 cm and 20-40 cm). [Result] (1) Different levels of simulated nitrogen deposition had significant impact on invertase and β-glucosidase at the soil depth of 0-20 cm (P<0.05), but no significant impact on catalase, urease, amylase, cellulase and polyphenol oxidase(P>0.05); invertase, polyphenol oxidase and β-glucosidase had significant response to nitrogen deposition at the soil depth of 20-40 cm (P<0.05), while catalase, urease, amylase and cellulose had no significant response (P>0.05). (2) The activities of invertase and polyphenol oxidase were enhanced at the soil depth of 0-20 cm, and that of P-glucosidase was inhibited. (3) With the deepening of nitrogen deposition, the activities of invertase and cellulose were enhanced at the soil depth of 20-40 cm; the activity of polyphenol oxidase was reduced in LN treatment, but increased in HN treatment; the activity of P-glucosidase was increased in LN treatment, but decreased in MN treatment. (4) With the deepening of soil layers, invertase and polyphenol oxidase responded similarly to simulated nitrogen deposition. [Condusion] The results provide certain scientific basis and fundamental data for better understanding and evaluating the effects of nitrogen deposition on enzyme activity in grassland soil. [ABSTRACT FROM AUTHOR]

Nitrogen deposition was simulated from July 2014 to August 2015 in the grassland, woodland and woodland-grassland border in Zhuqudeng Village, Bujiu Township, finzhi County, (CK, 0 kg·hm²2·-1; LN, 25 kg·hm²·a-1, MN, 50 kg·hm²·a-1; HN, 150 kg·hm²·a-1). NH4N03 was used as nitrogen source to analyze the number of microorganisms in soil layers of 0-20 cm and 20-40 cm and explore the effect of different degrees of nitrogen deposition on soil microorganisms in grassland woodland and woodland-grassland border. The results showed that: the number of bacteria in the grassland increased significantly under the treatment of LN, and the number of bacteria in the woodland grassland border and woodland had a rising response under the influence of nitrogen deposition; the number of actinomycetes in the grassland increased in MN and HN treatment, and significantly increased in the border and woodland under LN treatment; the number of molds decreased sharply in the grassland, woodland, and woodland-grassland border. [ABSTRACT FROM AUTHOR]

The impact on seedling recruitment by fallen wood of A. fabri forest in Tibet Sygera Mountain was studied. The results showed that regenerated seedlings on fallen wood roughly showed normal distribution, and there were more regenerated seedlings in the middle of fallen wood, while regenerated seedlings were fewer at two ends. FaNen wood at level IV had the most regenerated seedlings, followed by level-Ill fallen wood, and regenerated seedlings were the fewest on faNen wood at level V. The number and species of regenerated seedling on and around faNen wood on the west slope were more than that on the east slope. With the improvement of decomposition level, regenerated seedling per unit area firstly increased and then decreased, but the number of regenerated seedling on and around faNen wood was far more than that in woodland. [ABSTRACT FROM AUTHOR]