Characteristics of a 4-fold segmented clover detectore

Four high-purity germanium 4-fold segmented Clover detectors have been applied in the experiment of neutron-rich nucleus 21N. The performance of those four Clovers have been tested with radioactive sources and in-beam experiments, and the main results including energy resolution, peak-to-total ratios, the variation of the hit pattern distribution in different crystals of one Clover detector with the energy of γ ray, and absolute full energy peak detection effciency curve, were presented.     

Separation and determination of isoflavones in red clover by micellar electrokinetic capillary chromatography

A micellar electrokinetic capillary chromatography (MECC) method has been developed for the determination of the four isoflavones, i.e. biochanin A, formononetin, genstein and daidzein in red clover (Trifolium Pratense L.). The effect of running buffer pH and concentration were investigated. An electrolyte composed of 30 mm borate, 20 mm sodium dodecyl sulfate (SDS) and 4 mg/mL HP-beta-CD containing 5% (v/v) ethanol at pH 10.1 provides a satisfactory separation for all the analytes. The applied voltage was 25 kV, and the capillary temperature was kept constant at 25 degrees C with a UV detection at 254 nm. The relative standard deviations (RSD) of the migration time and peak area were less than 1.73 and 3.94% (intra-day), and 2.29 and 4.38% (inter-day), respectively, under the optimized separation conditions. Regression equations revealed a good linear relationship between the peak area of each compound and its concentration. The contents of the four compounds in red clover were successfully determined with satisfactory repeatability and recovery.     

Calorimetric characterization of grass during its decomposition

Grass is cultivated for bioenergy purposes yet and expected to play a more prominent role as a source of renewable energy in the future. Understanding its burning characteristics is thus crucial to optimize the energetic efficiency. The aim of this study was to reveal the effect of i) microbial decomposition and ii) enzymatic depolymerisation of grass on its thermal behaviour. Thermal characteristics of grass during the course of aerobic decomposition and of fresh samples after treatment by enzymatic hydrolysis were measured by differential scanning calorimetry (DSC). Heat of reaction, 50% burnoff values and positions and areas of peaks were taken as indicators for the thermal behaviour. An increase in biochemical stability of the grass during 140 days of decomposition was indicated by an exponential mass loss and decreasing specific CO₂ respiration rates. Parameters representing the thermal stability of the materials coincided with this pattern. The relative contribution of the thermolabile fraction decreased, and 50% burnoff values increased almost steadily during decomposition from 366 to 407°C. These thermal stability parameters are thus indicators for biochemical degradation. However, peak temperatures of the individual peaks continuously decreased during decomposition. A comparison of composted and fresh, cellulase-treated samples without long-term microbial decomposition indicated that enzymatic depolymerisation rather than microbial consumption of the plant tissue led to the observed decrease in peak temperatures.     

Parity of the band head at 3710 keV in 99Rh using clover detector as compton polarimeter

Clover detector has been used as a Compton polarimeter to measure the linear polarization of γ-rays produced in heavy ion fusion reaction. The polarization sensitivity of the clover detector has been measured over γ-ray energies ranging from 386 to 1368 ke V. The E1 multipolarity of the 1117 keV transition in ⁹⁹Rh has been established using this polarimeter. This has resulted in the assignment of negative parity to the band head at 3710 keV in ⁹⁹Rh.