[Application of near-infrared absorption spectrum scanning techniques in gas quantitative measurement].

A practical gas sensing system utilizing absorption spectrum scanning techniques was developed. Using the narrow-band transmission of a fiber tunable filter (TOF) and wavelength modulation technique, the so-called cross-sensing effects of the traditional spectrum absorption based gas sensor were reduced effectively and thus the target gas was detected sensitively and selectively. In order to reduce the effects of nonlinearity of TOF on the measurement results and improve the system stability in operation, the reflection spectrum of a reference FBG was monitored and employed to control the modulation region and center of TOF wavelength precisely. Moreover, a kind of weak signal detecting circuits was developed to detect the weak response signal of the system with high sensitivity. The properties of the proposed system were demonstrated experimentally by detection of acetylene. Approximate linear relationships between the system responses and the input acetylene concentrations were demonstrated by experiments. The minimum detectable acetylene of 5 x 10(-6), with signal-noise ratio of 3, was also achieved by experiments.

[Application of PSO algorithm in wavelength detection of FBG sensors].

In order to improve the measurement accuracy of FBG sensing system, particle swarm optimization (PSO) algorithm combined with reference FBGs array was applied to investigate the nonlinearity and hysteresis character of Fabry-Parot filter (FPF). A method of modeling the wavelength-voltage relationship of FPF online in each FPF scanning cycle was proposed in the present paper. The feature of particle swarm optimization algorithm such as fast convergence and simple implementation makes the process of modeling wavelength-voltage relationship of FPF be completed with low computing cost and high accuracy. With the set-up model, the absolute error in wavelength detection of FBG sensors was demonstrated by experiments to be as low as 0.03 nm. The structure of the system is compact and the proposed modeling approach has important meaning in FBG sensors system when FPF is used as wavelength demodulator.

[The relation between en-dormancy and changes in two main electron transport pathways of nectarine (Prunus persica var. nectariana) buds].

Respiration rate of buds of Prunus persica var. nectariana Maxim. cv. Shuguang and Mayfire was studied during dormancy. The results showed that the bud respiration rate changed with the stage of dormancy for both cultivars. Respiration rate of buds of the controls decreased steadily before dormancy, while increased slowly from November 5th for Shuguang and October 29th for Mayfire, and then decreased sharply on December 17th at which dormancy was terminated. Cyanide (KCN) only partially inhibited respiration rate of dormant buds of nectarine during the whole period, and the trend of the buds respiration rate followed the same pattern as the control samples during the entire period. Cyanide inhibited the respiration rate of dormant nectarine buds to roughly the same degree. The effect of salicylhydroxamic acid (SHAM) on bud respiration rate varied with time. SHAM decreased bud respiration rate before dormancy and after the release of dormancy, but increased bud respiration rate during dormancy. SHAM increased bud respiration rate more than three times at the beginning of dormancy for all buds and the degree decreased gradually along with the dormant period until turn to decrease the respiration rate again at the end of dormancy. KCN plus SHAM had the same effect on bud respiration rate as SHAM acting alone. The time KCN plus SHAM began to increase bud respiration rate or terminated was about 7 d earlier than SHAM did, which was closely associated with the different stage of dormancy.

[Effect of prefrontal infralimbic cortex GABAA receptor agitating on passive avoidance memory consolidation of rats].

In this study, one-trial step-through task was applied to reveal the effect of prefrontal infralimbic cortex GABAA receptor agitating on passive avoidance memory consolidation in rats. Immediately after training (with shock), GABAA receptor agonist, muscimol (0.5 µg/0.25 µL) or saline (0.25 µL) was infused into the test animal's infralimbic cortex, then, the latencies of rats stepping through the dark room were recorded. Meanwhile, local EEG power was adopted as index of the inactivation effect of muscimol. The step-through latencies of muscimol group were comparable(P>0.05)with saline group, but their local EEG power had decreased significantly (P<0.05). These results suggest that the inactivation of infralimbic cortex would not demolish the passive avoidance memory consolidation of rats.

[Effects of climate change on photosynthesis of Diospyros kaki under different soil moisture conditions].

Taking two-year-old Diospyros kaki as test material, this paper studied the effects of high CO2 concentration (700 micromol x mol(-1)), high temperature (5 degrees C higher than the mean daily temperature); and their combination on the net photosynthesis rate (Pn), evapotranspiration (Tr), stomatal conductance (Gs), water use efficiency (WUE), chlorophyll content, Fv/Fm, and Fv/Fo under different soil moisture conditions, with the ambient air temperature and CO2 concentration (380 micromol x mol(-1)) as the control. Under all test soil moisture conditions, the combination of high CO2 concentration and high temperature decreased the Tr and Gs, but increased the WUE. This combination increased the Pn when the soil moisture content was 75%-85% and 55%-65% of field capacity, but decreased the Pn when the soil moisture content was 35%-45%. High CO2 concentration increased the Pn and WUE but decreased the Gs and Tr under all test soil moisture conditions. The effects of high temperature and its combination with high CO2 concentration on the WUE depended on soil moisture condition, with the WUE increased with increasing soil moisture content. Comparing with the control, high CO2 concentration also increased the leaf Chla, Chlb, Chl (a + b), and Car concentrations and the Fv/Fm and Fv/Fo values, relieved the water stress, and increased the stress-resistance of D. kaki.