High performance infrared photodetectors up to 2.8 μm wavelength based on lead selenide colloidal quantum dots

The strong quantum confinement effect in lead selenide (PbSe) colloidal quantum dots (CQDs) allows to tune the bandgap of the material, covering a large spectral range from mid- to near infrared (NIR). Together with the advantages of low-cost solution processability, flexibility and easy scale-up production in comparison to conventional semiconductors especially in the mid- to near infrared range, PbSe CQDs have been a promising material for infrared optoelectronic applications. In this study, we synthesized monodisperse and high purity PbSe CQDs and then demonstrated the photodetectors working at different wavelengths up to 2.8 μm. Our high quality PbSe CQDs show clear multiple excitonic absorption peaks. PbSe CQD films of different thicknesses were deposited on interdigitated platinum electrodes by a simple drop casting technique to make the infrared photodetectors. At room temperature, the high performances of our PbSe CQD photodetectors were achieved with maximum responsivity, detectivity and external quantum efficiency of 0.96 A/W, 8.13 × 109 Jones and 78% at 5V bias. Furthermore, a series of infrared LEDs with a broad wavelength range from 1.5 μm to 3.4 μm was utilized to demonstrate the performance of our fabricated photodetectors with various PbSe CQD film thicknesses. © 2017 Optical Society of America

Adding Robustness in Dynamic Preemptive Scheduling

In this paper we introduce a robust earliest deadline scheduling algorithm for deal ing with hard aperiodic tasks under overloads in a dynamic realtime environment The algorithm synergistically combines many features including dynamic guarantees graceful degradation in overloads deadline tolerance resource reclaiming and dy namic reguarantees A necessary and sucient schedulability test is presented and an ecient On guarantee algorithm is proposed The new algorithm is evaluated via simulation and compared to several baseline algorithms The experimental results show excellent performance of the new algorithm in normal and overload conditions Static realtime systems are designed for worst case situations Assuming that all the assumptions made in the design and analysis are correct we can say that the level of guarantee for these systems is absolute and all tasks will make their deadlines Unfortunately static systems are not always possible becaus

Effects of cognitive-behavioral programs for criminal offenders

Cognitive-behavioral therapy (CBT) is among the more promising rehabilitative treatments for criminal offenders. Reviews of the comparative effectiveness of different treatment approaches have generally ranked it in the top tier with regard to effects on recidivism (e.g., Andrews et al., 1990; Lipsey & Wilson, 1998). It has a well-developed theoretical basis that explicitly targets “criminal thinking” as a contributing factor to deviant behavior (Beck, 1999; Walters, 1990; Yochelson & Samenow, 1976). And, it can be adapted to a range of juvenile and adult offenders, delivered in institutional or community settings by mental health specialists or paraprofessionals, and administered as part of a multifaceted program or as a stand-alone intervention. Meta-analysis has consistently indicated that CBT, on average, has significant positive effects on recidivism. However, there is also significant variation across studies in the size of those treatment effects. Identification of the moderator variables that describe the study characteristics associated with larger and smaller effects can further develop our understanding of the effectiveness of CBT with offenders. Of particular importance is the role such moderator analysis can play in ascertaining which variants of CBT are most effective. The objective of this systematic review is to examine the relationships of selected moderator variables to the effects of CBT on the recidivism of general offender populations

Hydrothermal deposition of CdS on vertically aligned ZnO nanorods for photoelectrochemical solar cell application

CdS/ZnO nanorods composite nanofilms were successfully synthesized via hydrothermal method on indium doped tin oxide glass substrates. Sequentially deposited CdS formed cauliflower like nanostructures on vertically aligned ZnO nanorods. The morphological, compositional, structural and optical properties of the films were characterized by field emission scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and ultraviolet–visible spectroscopy. Photoelectrochemical conversion efficiencies were evaluated by photocurrent measurements in a mixture of Na2S and Na2SO3 akaline aqueous solution. The amount of deposit, as well as the diameter and crystallinity of the CdS cauliflower were found to increase with growth time. CdS/ZnO nanorods composite exhibited greater photocurrent response than ZnO nanorod arrays. Besides, the composite film with 90 min of growth duration displayed the highest photocurrent density which is nearly four times greater than plain ZnO nanorods under the illumination of halogen light. The result exhibited remarkable photoconversion efficiency (η) of 1.92 %

Role of NaOH concentration on synthesis and characterization of β-V2O5 nanorods by solvothermal method

In this work, synthesis of β-V2O5 nanorods by solvothermal method was adopted at optimum experimental conditions by varying the concentration of NaOH as 0.5M, 1M, 1.5M and 2M. The obtained products were characterization by following techniques, XRD, RAMAN, FTIR, and FESEM. The XRD results reveal the formation of β-V2O5 nanorods and its crystalline nature was confirmed by its lattice parameters. The Raman analysis shows a peak at 485, 770 and 998 cm−1 corresponds to the vibration of O-V-O bonds. Similarly the FITR peaks appeared at the 530 and 786 cm−1 can be attributed to the symmetric stretching of Metal Oxide (V-O). The morphology and its structure of β-V2O5 nanorods can be analysized by the FESEM techniques and its images shows the formation of β-V2O5 nanorods with different dimensions. The role of concentration of NaOH can be studied by comparing the FESEM micrographs. It is clearly evident from FESEM images as the concentration of NaOH increases from 0.5 M to 2M, the shape and size of the change rapidly and the surface effect results in the mesoporous features on the surface of nanorods. Its note worthy as the concentration of NaOH increases results in the flattening of nanorods could be observed due more of interaction of NaOH precursor solution.Published versio