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We explored topography-dependent variations of spruce (Picea jezoensis var. komarovii) growth in response to climatic change, and abrupt decline in its climatic sensitivities to temperature under global warming in the Changbai Mountain, Northeast China. Variations in the mountain slope direction, being different in radiation intensity and soil moisture, might exert a profound influence on the growth-climate relationship, which potentially brings indeterminacy in sensitivity to temperature under climate warming. To better understand the spatial variation in this influence, we used dendrochronological methods to determine the relationship between the radial growth of spruce (P. jezoensis var. komarovii) and climate in three aspects at an elevation of approximate 1200 m in the Changbai Mountain. The results indicated obvious correlations among the three spruce chronologies, and the radial growth presented more positive correlations with spring temperature (rather than summer or winter temperature), with April temperature on the south-facing slope and negative with precipitation on the north- and west-facing slopes. Despite the sensitivities to temperature were abruptly declined by the increasing temperature, the year- occurrences were inconsistent with records from 1996, 1995 and 1989 on the north (in May), west (in May) and south (in Apr), respectively. The negative relationship with May precipitation has become stronger since 1982 on the north and west for the increasing amount of precipitation. Therefore, given the declined sensitivity of spruce growth to climate warming, which can be shown among three different slopes, the divergent point would be difficult to precisely disentangle in investigating the temporal stability base on the variation in species, habitat and data analytical method.

Two kinds of hybrid ultraviolet (UV) photodetectors based on TiO2 nanocrystals capped with and without oleic acid (OA) and poly(9,9-dihexylfluorene) (PFH) were prepared from solution and characterized to study the effects of the surface ligand on the device function. Both devices showed obvious photovoltaic effect, high UV-sensitive photoconductivity, and fast response time. The hybrid device containing TiO2 nanocrystals with bare surface exhibited a photocurrent density of 91 μA/cm2 at zero bias under 3.2 mW/cm2 UV irradiation, corresponding to a photosensitivity of 28.4 mA/W. The other device containing OA-capped TiO2 nanocrystals showed a photocurrent density of 19 μA/cm2 and a photosensitivity of 5.9 mA/W under the same condition. It was found that capping TiO2 with OA had a beneficial effect on its solubility in organic solvent. On the contrary, a barrier might be formed, significantly influencing the charge-transfer behavior. This negative effect overcompensated the positive influence due to improved morphology and lowered the photosensitivity of the device.