Structural, Vibrational and Thermodynamic Properties of AgnCu34-n Nanoparticles

We report results of a systematic study of structural, vibrational and thermodynamical properties of 34-atom bimetallic nanoparticles from the AgnCu34-n family using model interaction potentials as derived from the embedded atom method and in the harmonic approximation of lattice dynamics. Systematic trends in the bond length and dynamical properties can be explained largely on arguments based on local coordination and elemental environment. Thus increase in the number of silver atoms in a given neighborhood introduces a monotonic increase in bond length while increase of the copper content does the reverse. Moreover, based on bond lengths of the lowest coordinated (6 and 8) copper atoms with their nearest neighbors (Cu atoms), we find that the nanoparticles divide into two groups with average bond length either close to (~ 2.58 A) or smaller (~ 2.48 A) than that in bulk copper, accompanied by characteristic features in their vibrational density of states. For the entire set of nanoparticles, vibrational modes are found above the bulk bands of copper/silver. Furthermore, a blue shift in the high frequency end with increasing number of copper atoms in the nanoparticles is traced to a shrinkage of bond lengths from bulk values. The vibrational densities of states at the low frequency end of the spectrum scale linearly with frequency as for single element nanoparticles, however, the effect is more pronounced for these nanoalloys. The Debye temperature was found to be about one third of that of the bulk for pure copper and silver nanoparticles with a non-linear increase with increasing number of copper atoms in the nanoalloys.Comment: 37 pages, 12 figure

A new lower bounding scheme for the total weighted tardiness problem

Cataloged from PDF version of article.We propose a new dominance rule that provides a sufficient condition for local optimality for the 1\\Sigma w(i)T(i) problem. We prove that if any sequence violates the proposed dominance rule, then switching the violating jobs either lowers the total weighted tardiness or leaves it unchanged. Therefore, it can be used in reducing the number of alternatives for finding the optimal solution in any exact approach. We introduce an algorithm based on the dominance rule, which is compared to a number of competing approaches for a set of randomly generated problems. We also test the impact of the dominance rule on different lower bounding schemes. Our computational results over 30,000 problems indicate that the amount of improvement is statistically significant for both upper and lower bounding schemes. (C) 1998 Elsevier Science Ltd. All rights reserved

Distance to Headquarter and Real Estate Equity Performance

We study the effect of geographic portfolio diversification of real estate firms on their investment performance before and after the global financial crisis (GFC). In addition to previously used dispersion metrics, we also account for the distance of the properties to the corporate headquarters. We document a notable shift in the non-market performance of real estate companies after the crisis. Pre-GFC, we do not find a difference in non-market performance across equities based on geographic diversification. Post-GFC, equities with high geographic dispersion significantly outperform the market, while firms with concentrated property holdings do not deliver a significant alpha. Increased real estate equity market sophistication and strong institutional presence can explain why this effect is only observed for dispersed small firms, those invested outside gateway metro areas, or companies with low institutional ownership

Defatted yellow mealworm larvae (Tenebrio molitor l.) meal as possible alternative to fish meal in quail diets

The effects of replacing fish meal (FM) in the diet with defatted mealworm larvae meal (DMLM) on growth, carcass, and biochemical constituents of serum of Japanese quail chicks were investigated. A total of 600 unsexed one-day-old chicks were allotted to five dietary treatments with six replicates of 20 chicks each. The diets were formulated by replacing FM with DMLM at the levels of 25% (D25), 50% (D50), 75% (D75), and 100% (D100). The FM, D25 and D50 diets resulted in greater final bodyweight, higher bodyweight gain, and improved feed conversion ratio compared with the other diets. Diets that contained DMLM decreased the feed intake compared with the FM diet. The FM and D25 diets increased the hot and cold carcass yields compared with the other diets, whereas the D75 and D100 diets significantly enhanced the relative weight of the small intestine and abdominal fat compared with FM, D25, and D50. The replacement of FM with DMLM reduced the serum globulin, total cholesterol and triglyceride levels, and the albumin to globulin ratio significantly. The best protein and energy efficiency ratios and European efficiency factor were obtained with the D25 and D50 diets. In conclusion, the replacement of FM with DMLM at the levels of 25% and 50% produced positive results in growth performance, in serum albumin to globulin ratio, and in nutrient use efficiency in quail.Keywords: performance, serum biochemistry, slaughterin

External magnetic field effects on a distorted kagome antiferromagnet

We report bulk magnetization, and elastic and inelastic neutron scattering measurements under an external magnetic field, $H$, on the weakly coupled distorted kagome system, Cu_{2}(OD)_3Cl. Our results show that the ordered state below 6.7 K is a canted antiferromagnet and consists of large antiferromagnetic $ac$-components and smaller ferromagnetic $b$-components. By first-principle calculations and linear spin wave analysis, we present a simple spin hamiltonian with non-uniform nearest neighbor exchange interactions resulting in a system of coupled spin trimers with a single-ion anisotropy that can qualitatively reproduce the spin dynamics of Cu_{2}(OD)_3Cl.Comment: 5 figure

Activities of two Major Lichen Compounds, Diffractaic Acid and Usnic Acid against Leptinotarsa decemlineata Say, 1824 (Coleoptera: Chrysomelidae)

Two major lichen compounds (diffractaic and usnic acids), isolated from Usnea longissima Ach. were tested against 4th instar larvae and adults of the Colorado potato beetle, Leptinotarsa decemlineata Say for 24, 48, 72 and 96 h under laboratory conditions. Durations and mortalities were recorded at various concentrations (1.25, 2.5, 5, and 10 mg. ml-1). Results showed that secondary metabolites of U. longissima had a significant insecticidal potential against larvae and adults of L. decemlineata. Mortality rates after 96 h of treatment, with the highest concentration (10 mg. ml-1) of diffractaic and usnic acids, were 100 and 70% for adults and 100 and 80% for larvae, respectively. No mortality was observed in the control treatment. Bioassay tests with diffractaic and usnic acids revealed that the 96 h median lethal concentration (LC50) values were 1.783 and 4.048 mg. ml-1 for adults and 1.509 and 2.759 mg. ml-1, for larvae of L. decemlineata, respectively. The present results suggest that the lichen secondary metabolites may have a potential action for control of L. decemlineata 4th instar larvae and adults

Discrete element modelling of hydraulic fracture interaction with natural fractures in shale formations

Research presented in this paper aimed at establishing a better understanding of natural fracture (NF)/hydraulic fracture (HF) interaction mechanisms and fracture network development in naturally fractured and nonhomogeneous shale formations through numerical modelling using the two-dimensional particle flow code (PFC2D). Hydraulic fracture propagation was firstly modelled in a 30 m x 30 m model representing intact rock by bonded particle method (BPM), which served as a base case in the research. Then a single, deterministic natural fracture was embedded into the same model by a smooth joint contact model (SJM) to investigate different NF/HF interaction mechanisms under a range of different conditions by varying the angle of approach, differential horizontal stress, and the mechanical properties of a fracture within the model. Based on the parametric research findings, number and diversity of natural fractures in the model were increased both deterministically and stochastically, and the results are compared and discussed

Parasitic Appendicitis From Past to Present in Turkey

Background: Understanding the etiology of appendicitis is important for developing effective treatments the rela­tionship between parasitic appendicitis and various socio-cultural factors were examined, particu­larly with respect to the incidence of literacy. The aim of the article was to research the relations between para­sitic appendicitis and literacy ratio in population.Methods: Cases of parasitic appendicitis resulting in surgery performed at Buca Seyfi Demirsoy Large State Hospital Surgery Clinic between 2002 and 2009 were retrospectively reviewed and classified accord­ing to age, sex, type of parasite, morbidity, and mortality. Studies conducted in different regions of Turkey as well as in other countries were reviewed to determine if there was a relationship between para­sitic appendicitis and literacy. Results: Of the 1,969 appendectomy cases reviewed, nine were classified as parasitic appendicitis (0.45%). Enterobius vermicularis was observed in seven cases and Taenia spp. in two. The average age was 26.4 yr. No morbidity or mortality was found.Conclusion: The data were compared with a retrospective review of studies conducted in the same regions and a decrease in the rate of parasitic appendicitis was observed during the period between the two re­views. It was determined that a low literacy rate was associated with an increase in the incidence of para­sitic appendicitis. Observations made between different countries also produced similar results. In coun­tries where the incidence of parasitic appendiciticis was greater than 1.5%, the literacy rate was less than 88%. To avoid appendectomy resulting from parasites, it is important to increase education and literacy. In some areas, individuals with appendicitis undergo surgery due to a lack of education or poor literacy