RESUMEN
We describe a theoretical model to analyze temperature effects on the Kretschmann surface plasmon resonance (SPR) sensor, and describe a new double-incident angle technique to simultaneously measure changes in refractive index (RI) and temperature. The method uses the observation that output signals obtained from two different incident angles each have a linear dependence on RI and temperature, and are independent. A proof-of-concept experiment using different NaCl concentration solutions as analytes demonstrates the ability of the technique. The optical design is as simple and robust as conventional SPR detection, but provides a way to discriminate between RI-induced and temperature-induced SPR changes. This technique facilitates a way for traditional SPR sensors to detect RI in different temperature environments, and may lead to better design and fabrication of SPR sensors against temperature variation.
RESUMEN
The present paper proposes an optical chemistry sensor used for real-time detection of trace Cu2+, including the optical perception module and the signal processing module. The optical perception module gives the output of the laser light and excitation of fluorescence. The signal processing module completes optoelectronic conversion and amplification of the weak fluorescence signal as well as data processing and display. A self-developed optical acquisition, conversion and processing system was used to complete rapid detection of trace Cu2+, miniaturizing and reducing the cost of the testing instruments. The experimental results show the proposed sensor responds linearly in a concentration range of 30-1 000 nmol L(-1), with the linear equation y = 0.109 77x + 11.872 32, the linearity 0.994 82, the standard deviation 3.994 24, the detection limit 30 nmol x L(-1), and the response time of the sensor 40 seconds. The experiment determines the interference of other ions with the Cu2+ test results. It shows that this sensor meets the demand of field detection for trace Cu2+ site testing.
RESUMEN
To evaluate effects of nitrogen rates on soil respiration, we measured the diurnal and seasonal dynamic changes and the contents of the soil organic carbon (SOC), soil dissolved organic carbon (DOC), soil microbial biomass carbon (MBC), and total soil nitrogen (TSN) under different growing seasons of winter wheat under the continuous systems from March in 2008 to March in 2009 at Changwu ecological station of the Chinese Academy of Sciences. The experiment consists of five nitrogen rates: 0 (N0), 45 (N45), 90 (N90), 135 (N135), and 180 (N180) kg/hm2. Soil respiration rate significantly enhanced with increasing nitrogen rate ranging from 0 to 90 kg/hm2 and increased little from 90 to 135 kg/hm2, but decreased with increasing nitrogen rate from 135 to 180 kg/hm2. At the seasonal change scale, there were an active phase of soil respiration from March to October and a weak phase of soil respiration from November to February. At the annual change scale, the fluctuate range of the treatments N0, N45, N90, N135, and N180 were 0.27-2.01 micromol/(m2 x s), 0.36-2.26 micromol/(m2 x s) 0.58-2.56 micromol/(m2 x s), 0.65-2.94 micromol/(m2 x s), and 0.58-2.6 micromol/(m2 x s), respectively. Nitrogen fertilization significantly affected the dynamic changes of DOC and MBC. There were significant positive correlations between soil respiration rate and DOC and MBC, while significant negative correlations with the C/N ratio.