A comparative study on structural,morphological and photocatalytic properties of anodically grown ZnO nanowires under varying parameters

Journal of Materials Science: Materials in Electronics - In this study, zinc oxide (ZnO) nanowires (NWs) were successfully produced on Zn plates through electrochemical anodization in potassium...     

LEARNING AND VERIFYING SAFETY CONSTRAINTS FOR PLANNERS IN A KNOWLEDGE‐IMPOVERISHED SYSTEM

We present a Bayesian approach to learning flexible safety constraints and subsequently verifying whether plans satisfy these constraints. Our approach, called the Safety Constraint Learner/Checker (SCLC), infers safety constraints from a single expert demonstration trace and minimal background knowledge, and applies these constraints to the solutions proposed by multiple planning agents in an integrated and heterogeneous ensemble. The SCLC calculates how much to blame plan fragments (partial solutions) generated by the individual planning agents. This information is used when composing these fragments into a final overall plan. In particular, fragments whose safety violations exceed a threshold are rejected. This facilitates the generation of safe plans. We have integrated the SCLC within the Generalized Integrated Learning Architecture, which was designed for Defense Advanced Research Projects Agency (DARPA)’s Integrated Learning (IL) program. The main goal of the IL program is to promote the development and success of sophisticated systems that learn to solve challenging real‐world problems based on a simple demonstration by a human expert and exiguous domain knowledge. We present experimental results showing the advantages of the SCLC on two multiagent problem‐solving tasks that were benchmark applications in DARPA’s IL program.     

The effect of combined use of chitosan and PIPS on push-out bond strength of root canal filling materials

Adhesion of root canal filling materials to root dentin is important for the long-term success of the treatment. Push-out bond strength test is used to evaluate the adhesion capacity of root canal filling materials to root canal walls. The aim of the present study is to compare the bond strength of root canal filling materials to root dentin after irrigation with EDTA, chitosan and the combination of chitosan and PIPS irridation using push-out bond strength test. Forty-eight extracted teeth were resected until 13-mm long roots were obtained. Root canals were prepared with a size-25 OneShape instrument. Samples were divided into three groups each including 15 roots. Group 1: Canals were rinsed with 0.2% chitosan and subjected to laser irridation with PIPS at the same time. Group 2: Canals were rinsed with 0.2% chitosan. Group 3: Canals were rinsed with EDTA. All canals were filled with .06 tapered gutta-percha and AH-plus sealer. One-mm thick slices were taken from coronal, middle and apical one-thirds of the roots. Push-out bond strength was determined using a Universal Testing Machine. One root from each group was observed under SEM to evaluate the degree of smear removal. Statistical analysis was performed with Kruskall-Wallis test. Results showed that bond strength values were statistically similar in overall evaluation for all groups (p > .05). In segmental evaluation, group 1 revealed the highest bond strength in apical one-third compared to other groups (p < .05).     

Intercomparison of the Realizations of the ITS-90 from 83.8058 K to 692.677 K among European NMIs

The EUROMET.T-K3 comparison is the regional extension of CCT-K3. The comparison involved the six European national metrology institutes (NMIs) previously involved in CCT-K3 (LNE-INM/CNAM, SMU, INRiM, NMi-VSL, NPL, PTB) and 18 additional European national laboratories. The comparison was divided into five different loops, each coordinated by a co-pilot chosen from the laboratories having participated in the CCT-K3 comparison. LNE-INM/CNAM played the role of pilot in linking the five loops. In each loop, an artifact in the form of a standard platinum resistance thermometer (SPRT, 25 Ω) was circulated among the participating laboratories. To have sufficient information about the possible drift of the SPRTs, the co-pilots performed a calibration over the full temperature range at the beginning and at the end of the loop. A EUROMET reference value (ERV), taking into account the whole comparison, was defined, and the differences (T _Lab − T _ERV) were calculated with the associated uncertainties. The method for establishing the link between the participants in CCT-K3 and in EUROMET.T-K3 is described. Institut National de Métrologie (BNM-INM/CNAM at the time of the comparison, LNE-INM/CNAM since 1 January 2005), Paris, France.     

Efficiency improvement and NOx emission reduction potentials of two‐stage turbocharged Miller cycle for stationary natural gas engines

As a part of an engine research and development project in cooperation with industry, a V20 engine is designed with two‐stage high‐pressure turbocharging, and the potential of the Miller cycle is examined through calculations using computational models based on experimental as well as computational studies. The stationary gas engines must produce less than 250 mg Nm^?3 in 5% excess of O₂, additionally the amount of NO_x emissions and their dependence on engine operational and design conditions are investigated by using a zero‐dimensional reaction kinetic model. The results show an increase in efficiency, also the amount of NO_x emissions is kept under the constraint value of 250 mg Nm^?3 for stationary engines. The results obtained here promise a very high improvement potential for future emission regulations. Copyright © 2004 John Wiley & Sons, Ltd.     

Evaluation of ISSR markers for genetic diversity analysis in Anatolian water buffaloes

BACKGROUND: The utilisation of molecular markers has increased in molecular research recently. Inter‐simple sequence repeat (ISSR) markers allow the analysis of genomes without preliminary sequence information, since random primers are used. The purpose of the present study was to evaluate ISSR markers for assessing the genetic diversity of indigenous Anatolian Water Buffaloes reared in Afyon, Konya and Sivas provinces of Turkey, with a view to conservation of the gene resources. RESULTS: The 11 ISSR primers chosen for the analysis revealed a total of 110 bands, of which 76 (69.09%) were polymorphic. Also, genetic similarity, polymorphic information content (PIC), resolving power (R_p) and mean resolving power (R_p ), heterozygosity (H) and Shannon index (I) were calculated as 0.9479–0.9562, 0.35 ± 0.20, 2.73, 0.27, 0.18 ± 0.07 and 0.28 ± 0.11, respectively. CONCLUSION: The ISSR markers were found to be promising for assessing the genetic diversity in buffalo populations. Potential genetic parameters such as PIC, R_p, R_p , H and I were effectively used in this study. Copyright © 2011 Society of Chemical Industry     

Solar-blind ultraviolet photodetector based on Ti-doped Ga2O3/Si p–n heterojunction

A solar-blind ultraviolet photodetector based on Ti-doped Ga₂O₃/Si p–n heterojunction is demonstrated for the first time. It is found that the heterojunction quality forming between Ga₂O₃ and Si becomes better after Ti incorporation in Ga₂O₃. The current–voltage and temporal response measurements show that the detector based on Ti-doped Ga₂O₃/Si p–n heterojunction has a responsivity of 0.382 A/W and a fast rise time of 73 ms as well, which are much better than those undoped Ga₂O₃/Si p–n heterojunction analogues.

     

Detailed analysis on thermal,microstructural, mechanical,and morphological features of side chain liquid crystalline polymer/isotactic polypropylene graft copolymers: Effect of grafted and ungrafted polymer units

The main scope of this comprehensive study is to investigate the effects of poly(p-benzophenoneoxycarbonylphenyl acrylate), poly(BPOCPA), which presenting as only graft units or both graft and ungrafted units in the matrix, on the fundamental features of isotactic polypropylene (IPP). The graft copolymerization of BPOCPA onto IPP was performed with the aid of bulk melt polymerization at varying monomer content levels ranging from 5% to 40%. The thermal behavior, crystal quality, mechanical performance, and surface morphology of the samples were investigated by means of differential scanning calorimeter, X-ray diffractometer (XRD), universal mechanical test, and scanning electron microscope (SEM) techniques. Thermal analyses depicted that there existed the noteworthy enhancements in both crystalline melting temperatures and percent crystallinities of matrix polymers. Furthermore, according to XRD results, a and b parameters increased significantly at low percentages of the graft units, while the parameter c decreased in all products in consistence with the content. As for the mechanical characterization, the grafting led to remarkable improvements in modulus, tensile and impact strength of the products. SEM micrographs indicated that the samples were completely homogeneous without any phase separation and the products exhibited brittle nature with some ductility.     

Covalent Immobilization of Tyrosinase on Electrospun Polyacrylonitrile/Polyurethane/Poly(m-anthranilic acid) Nanofibers: An Electrochemical Impedance Study

Polyacrylonitrile/polyurethane/poly(m-anthranilic acid) nanofibers were fabricated by electrospinning. Tyrosinase immobilization was performed by EDC/N-hydroxyl succinimide activation. Covalent binding of tyrosinase onto nanofibers was confirmed by Fourier transform infrared-attenuated total reflectance, and bicinchoninic acid assay revealed the amount of enzyme. Nanofiber morphology and composition were characterized by scanning electron microscopy/energy-dispersive X-ray spectroscopy (EDX). Nanofibers became smoother and thicker after tyrosinase immobilization. Effects of enzyme on nanofibers were investigated by electrochemical impedance spectroscopy and the data were fitted to equivalent electrical circuit model. EDX-mapping showed uniform distribution of enzyme. The solution resistance and charge transfer resistance of nanofibers decreased after enzyme immobilization.     

Strength and elastic properties of structural lightweight concretes

The study presents the influence of characteristics of four aggregate types (two sintered lightweight fly ash aggregates, cold-bonded lightweight fly ash aggregate and normalweight crushed limestone aggregate) on the strength and elastic properties of concrete mixtures. Different models were also used in order to predict the strength and modulus of elasticity values of concretes. The results of this study revealed the achievement of manufacturing high-strength air-entrained lightweight aggregate concretes using sintered and cold-bonded fly ash aggregates. In order to reach target slump and air content, less amount of chemical admixtures was used in lightweight concretes than in normal-weight concrete, leading to reduction in production cost. The use of lightweight aggregates (LWA) instead of normalweight aggregates in concrete production slightly decreased the strength. The models given by codes, standards and software and equation derived in this study gave close estimated values to the experimental results.