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With the global shortage of ³He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B12As2) for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B12As2 bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A·W-1 and 2.47 mA⋅cm-2, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K) were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B12As2 bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to µA, 1-100 µA⋅cm-2 and 7.6x105-7.7x10³ δ⋅cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B12As2 is a potential candidate for thermal-neutron detectors. [ABSTRACT FROM AUTHOR]

Genetic potential and combining ability were studied in 6 × 6 F1 cross of Gossypium hirsutum L. at the University of Agriculture, Peshawar, Pakistan. Six parental genotypes (CIM-446, CIM-496, CIM-499, CIM-506, CIM-554 and CIM- 707) and their 30 F1 diallel progenies were grown in a randomized complete block design with three replications. Significant (p<0.01) differences were observed among the genotypes for bolls per sympodia, bolls per plant, boll weight, seed cotton yield per plant, lint % and lint index. F1 hybrids showed significant increase over parental means for all the traits. Mean squares due to GCA and SCA were highly significant for all the traits. The GCA mean squares were higher than SCA for majority traits which revealed that additive genes controlled the inheritance. Utilization of best general combiners (CIM-446 and CIM-554) as one of the parents produced promising F1 population (CIM-446 × CIM-554, CIM-446 × CIM-496 and CIM-506 × CIM-554) with desirable SCA and mean performance for yield and fiber traits. Therefore, high × low, low × high and in some cases high × high GCA parents showed best performance for majority traits. Correlation of seed cotton yield was significantly positive with yield related traits however, the association was negative with lint %. Additive gene action controlled the inheritance, and selection in above promising hybrids could be used in early segregating generations and in hybrid cotton production to enhance the seed cotton yield. [ABSTRACT FROM AUTHOR]

We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Current Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from 1 to 30 V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material. [ABSTRACT FROM AUTHOR]

We obtained high-quality CdTexSe1-x (CdTeSe) crystals from ingots grown by the vertical Bridgman technique. The compositional uniformity of the ingots was evaluated by X-ray fluorescence at BNL's National Synchrotron Light Source X27A beam line. The compositional homogeneity was highly uniform throughout the ingot, and the effective segregation coefficient of Se was ~1.0. This high uniformity offers potential opportunity to enhance the yield of the materials for both infrared substrate and radiation-detector applications, so greatly lowering the cost of production and also offering us the prospect to grow large-diameter ingots for use as large-area substrates and for producing higher efficiency gamma-ray detectors. The concentration of secondary phases was found to be much lower, by eight- to ten fold compared to that of conventional CdxZn1-xTe (CdZnTe or CZT). [ABSTRACT FROM AUTHOR]

Chickpea (Cicer arietinum L.) germplasm, collected from diverse research centers of the world were characterized for nodulation (Nod[sup +] or Nod[sup -]) and evaluated for response to seed inoculation with Rhizobium leguminosarum in terms of number of nodules plant[sup -1] and seed yield plant[sup -1]. Forty three genotypes, procured from Nuclear Institute for Food and Agriculture (NIFA) Peshawar, Gram Research Station (GRS) Karak and International Center for Agricultural Research in Dry Areas (ICARDA), Syria, showed nodulation (Nod[sup +]) while four genotypes, received from International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), India failed to produce any nodule (Nod[sup -]). Pooled analysis of variance for both the traits revealed highly significant differences among genotypes, interaction of genotypes with treatment and also between treatments (inoculated and un-inoculated/control). Inoculated genotypes exceeded control in treatment means both for nodules plant[sup -1] (10.86 and 7.86) and seed yield plant[sup -1] (15.1 g and 10.0 g). High heritability estimates for nodules plant[sup -1] (53.2) and seed yield plant[sup -1] (77.0) as well as low level of differences among PCV and GCV of both the traits showed that genotypes played more influential role in the expression of these characters. It is concluded that the studied germplasm could be successfully utilized in future breeding programs. Furthermore, Genotypes Karak-3 is recommended for general cultivation and NDC 5-S10 for crop rotation programs. [ABSTRACT FROM AUTHOR]

Objective: To compare long-term results of percutaneous iliac artery stenting (PCIS) with aortobifemoral (ABF) grafting for patients with symptomatic iliac artery occlusions. Methods: A retrospective review of 229 patients (January 2000 to December 2011) with symptomatic iliac artery occlusions was performed. In 100 patients, 103 PCIS procedures were performed, and 101 patients underwent ABF grafting. Outcome data including periprocedural complications, improvement in ankle-brachial index, morbidity, and mortality were collected in a vascular registry. Kaplan-Meier estimates for patency and survival were analyzed. Univariate (Fisher exact test) and multivariate analyses of variables associated with the loss of primary patency were performed. Results: Patients in the ABF grafting group were younger (60 ± 0.9 years old vs 65 ± 1.2 years old; P = .002) and more commonly had a history of nicotine abuse (97% vs 86%; P = .002), chronic obstructive pulmonary disease (85% vs 70%; P = .02), and a greater incidence of superficial femoral artery disease (45% vs 24%; P = .001). The most common presenting symptoms in both groups consisted of intermittent claudication (66% ABF vs 71% PCIS), rest pain (20% ABF vs 17% PCIS), and ulceration or gangrene of toes (14% ABF vs 15% PCIS). At 72 months, the primary patency for ABF bypass was greater than for PCIS (91% vs 73%; P = .010). Secondary patency rates were equivalent in both groups (98% ABF vs 85% PCIS). Survival in the ABF bypass group was significantly greater than in the PCIS group (76% vs 68%; P = .013). Hyperlipidemia (hazard ratio, 2.55; P = .049) and concurrent superficial femoral artery lesion (hazard ratio, 2.61; P = .026) were factors associated with the loss of primary patency for the entire cohort. The average hospital stay was 7 ± 2 days in the ABF group and 1 ± 0.3 days in the PCIS group (P = .0001). There were no periprocedural deaths in the PCIS group; there were four deaths in the ABF group (P = .058). In the PCIS group, ankle-brachial index increased from 0.66 to 0.89, and in the ABF group, ankle-brachial index increased from 0.54 to 0.98 (both groups, P < .001). Conclusions: This study demonstrates that PCIS remains a suitable, less invasive first-line therapy for iliac artery occlusions. PCIS has lower morbidity, shorter hospital length of stay, and equivalent secondary patency but inferior primary patency compared with ABF. [Copyright &y& Elsevier]

In this study, the sensitivity caused by the input parameters, such as Lewis number ( L e ), thermophoresis parameter ( N t ) and Brownian motion parameter ( N b ) of a nanofluid flow past a stretching flat surface is studied using response surface methodology (RSM). The mathematical model is solved using numerical technique and Nusselt and Sherwood numbers are considered as quantities of interest. The involved parameters, such as Lewis number, thermophoresis parameter and Brownian motion parameter, are varied for arbitrary values in the interval. A central composite design is used to obtain the quadratic model for the output, such as Nusselt and Sherwood numbers. It is found that reduced Nusselt number is most sensitive towards the Brownian motion parameter ( N b ) in the interval 5 ≤ L e ≤ 25 . Sherwood number is sensitive towards thermophoresis parameter in the interval 5 ≤ L e ≤ 25 for fixed Brownian motion parameter ( N b = 0.3 ). [ABSTRACT FROM AUTHOR]

We investigated structural defects in CdZnTe detector-grade crystals grown under different conditions. Here, we report our findings from high-resolution electron microscopy [transmission electron microscopy (TEM) and scanning TEM (STEM)] and scanning electron microscopy integrated with energy-dispersive x-ray spectroscopy to characterize the material's structural and chemical composition. Combining these techniques gave us important information about the defects, their concentration, and the elemental composition of the CdZnTe crystals. Our experimental observations demonstrated some distinct nanostructural defects in the crystals that may play a major role in device performance. [ABSTRACT FROM AUTHOR]

We investigated the effects of post-growth annealing on cadmium zinc telluride crystals intended for use as room-temperature radiation detectors. Annealing under Cd vapor effectively eliminated Te inclusions. The material's resistivity was lowered, and loss of Zn component was observed. Annealing under Cd + Zn vapors similarly removed Te inclusions. Furthermore, after exposure to the two vapors, we noted a change in the crystal surface morphology, i.e., formation of patterns of parallel lines. In contrast to annealing under Cd vapor alone, high resistivity was maintained after suitably controlling the Cd and Zn pressures. [ABSTRACT FROM AUTHOR]

We studied, by current deep-level transient spectroscopy (I-DLTS), point defects induced in CdZnTe detectors by three dopants: Pb, Bi, and In. Pb-doped CdZnTe detectors have a new acceptor trap at around 0.48 eV. The absence of a V trap suggests that all Cd vacancies are compensated by Pb interstitials after they form a deep-acceptor complex [[Pb]-V]. Bi-doped CdZnTe detectors had two distinct traps: a shallow trap at around 36 meV and a deep donor trap at around 0.82 eV. In detectors doped with In, we noted three well-known traps: two acceptor levels at around 0.18 eV (A-centers) and 0.31 eV (V), and a deep trap at around 1.1 eV. [ABSTRACT FROM AUTHOR]

The behavior of the internal electric field of nuclear-radiation detectors substantially affects detector performance. We investigated the distribution of the internal field in cadmium zinc telluride (CZT) detectors under high carrier injection. We noted the build-up of a space-charge region near the cathode that produces a built-in field opposing the applied field. Its presence entails the collapse of the electric field in the rest of the detector, other than the portion near the cathode. Such a space-charge region originates from serious hole trapping in CZT. The device's operating temperature greatly affects the width of the space-charge region. With increasing temperature from 5°C to 35°C, its width expanded from about one-sixth to one-half of the total depth of the detector. [ABSTRACT FROM AUTHOR]