Effects of Te inclusions on the performance of CdZnTe radiation detectors

Te inclusions existing at high concentrations in CdZnTe (CZT) material can degrade the performance of CZT detectors. These microscopic defects trap the free electrons generated by incident radiation, so entailing significant fluctuations in the total collected charge and thereby strongly affecting the energy resolution of thick (long-drift) detectors. Such effects were demonstrated in thin planar detectors, and, in many cases, they proved to be the dominant cause of the low performance of thick detectors, wherein the fluctuations in the charge losses accumulate along the charge's drift path. We continued studying this effect using different tools and techniques. We employed a dedicated beamline recently established at BNL's National Synchrotron Light Source for characterizing semiconductor radiation detectors, along with an IR transmission microscope system, the combination of which allowed us to correlate the concentration of defects with the devices performances. We present here our new results from testing over 50 CZT samples grown by different techniques. Our goals are to establish tolerable limits on the size and concentrations of these detrimental Te inclusions in CZT material, and to provide feedback to crystal growers to reduce their numbers in the material

Blood-feeding patterns of <it>Anopheles </it>mosquitoes in a malaria-endemic area of Bangladesh

<p>Abstract</p> <p>Background</p> <p>Blood-feeding patterns of mosquitoes are crucial for incriminating malaria vectors. However, little information is available on the host preferences of <it>Anopheles </it>mosquitoes in Bangladesh. Therefore, the objective of the present study was to determine the hematophagic tendencies of the anophelines inhabiting a malaria-endemic area of Bangladesh.</p> <p>Methods</p> <p>Adult <it>Anopheles </it>mosquitoes were collected using light traps (LTs), pyrethrum spray (PS), and human bait (HB) from a malaria-endemic village (Kumari, Bandarban, Bangladesh) during the peak months of malaria transmission (August-September). Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) were performed to identify the host blood meals of <it>Anopheles </it>mosquitoes.</p> <p>Results</p> <p>In total, 2456 female anopheline mosquitoes representing 21 species were collected from the study area. <it>Anopheles vagus </it>Doenitz (35.71%) was the dominant species followed by <it>An. philippinensis </it>Ludlow (26.67%) and <it>An. minimus </it>s.l. Theobald (5.78%). All species were collected by LTs set indoors (n = 1094), 19 species were from outdoors (n = 784), whereas, six by PS (n = 549) and four species by HB (n = 29). Anopheline species composition significantly differed between every possible combination of the three collection methods (χ²test, P < 0.001). Host blood meals were successfully detected from 1318 (53.66%) <it>Anopheles </it>samples belonging to 17 species. Values of the human blood index (HBI) of anophelines collected from indoors and outdoors were 6.96% and 11.73%, respectively. The highest values of HBI were found in <it>An. baimai </it>Baimaii (80%), followed by <it>An. minimus </it>s.l. (43.64%) and <it>An. annularis </it>Van den Wulp (37.50%). <it>Anopheles baimai </it>(<it>B_i</it>= 0.63) and <it>An. minimus </it>s.l. (<it>B_i</it>= 0.24) showed strong relative preferences (<it>B_i</it>) for humans among all hosts (human, bovine, goats/sheep, and others). <it>Anopheles annularis</it>, <it>An. maculatus </it>s.l. Theobald, and <it>An. pallidus </it>Theobald exhibited opportunistic blood-feeding behavior, in that they fed on either humans or animals, depending on whichever was accessible. The remaining 12 species preferred bovines as hosts.</p> <p>Conclusions</p> <p>The observed high anthropophilic nature of <it>An. baimai</it>, <it>An. minimus </it>s.l., and <it>An. annularis </it>revealed these species to be important malaria vectors in hilly areas of Bangladesh. Higher values of HBI in outdoor-resting mosquitoes indicated that indoor collection alone is not adequate for evaluating malaria transmission in the area.</p