Diameter and Chirality Dependence of Exciton Properties in Carbon Nanotubes

We calculate the diameter and chirality dependences of the binding energies, sizes, and bright-dark splittings of excitons in semiconducting single-wall carbon nanotubes (SWNTs). Using results and insights from {\it ab initio} calculations, we employ a symmetry-based, variational method based on the effective-mass and envelope-function approximations using tight-binding wavefunctions. Binding energies and spatial extents show a leading dependence with diameter as $1/d$ and $d$, respectively, with chirality corrections providing a spread of roughly 20% with a strong family behavior. Bright-dark exciton splittings show a $1/d^2$ leading dependence. We provide analytical expressions for the binding energies, sizes, and splittings that should be useful to guide future experiments

Theory and it ab initio calculation of radiative lifetime of excitons in semiconducting carbon nanotubes

We present theoretical analysis and first-principles calculation of the radiative lifetime of excitons in semiconducting carbon nanotubes. An intrinsic lifetime of the order of 10 ps is computed for the lowest optically active bright excitons. The intrinsic lifetime is however a rapid increasing function of the exciton momentum. Moreover, the electronic structure of the nanotubes dictates the existence of dark excitons nearby in energy to each bright exciton. Both effects strongly influence measured lifetime. Assuming a thermal occupation of bright and dark exciton bands, we find an effective lifetime of the order of 10 ns at room temperature, in good accord with recent experiments.Comment: 12 pages, 3 figure

Effect of repeated applications of fipronil on arthropod populations in experimental plot studies

The effect of two applications of fipronil on arthropod populations were studied under experimental plot conditions using 3-month old Cuphea ignea. Eighty-one families belonging to 12 orders of Arthropoda were trapped before spraying. The four dominant orders were Hymenoptera (28.6%), Homoptera (19.1 %), Collembola (17.8 %) and Diptera (16.2 %). Other orders were present in small numbers i. e. Hemiptera, Coleoptera, Orthoptera, Thysanoptera, Araneida, Acarina, Lepidoptera and Isopoda. The abundance of arthropods was reduced to 44 and 47 families after the first and second sprayings, respectively. The percentage population of Collembola increased significantly after the first and second sprayings as compared to the number before treatment. The percentage population ofHomoptera (Aleyrodidae) increased after the first spray but declined after the second spray. The family Isotomidae (Collembola) increased significantly after the first and second sprays. Some orders such as Isopoda and Lepidoptera disappeared after the plot was treated with fipronil

Ameliorative Effect of Folic Acid on the Neurological Changes in Rats Treated with Methotrexate

Methotrexate (MTX) is an antimetabolite of the normal folic acid produced by human and animal bodies. MTX antagonizes Folic Acid which is vital for purine and many vital amino acids. Treatment with MTX has been widespread all over the world recently. Physicians usually prescribe folic acid together or following treatment with MTX. Some patients minimize the importance of having folic acid with MTX or after it regarding it as a not essential drug as MTX. From here it comes, the value of this research to clarify the important role of folic acid in minimizing the side effects of MTX. In fact this effect applies on most systems in the human and animal bodies; however, authors prefer to focus on the neurological aspects as references are somewhat scarce especially in the veterinary aspect and found some behavioral changes which coincide with brain histopathological findings. Keywords: methotrexate, folic acid, neurological changes, rat

Determination of physical properties and thermal conductivity of graphite foam with image analysis

Since pore network structures of porous materials have irregular shapes and may vary in size, the accurate characterization and virtual 3D reconstruction of these materials are of great importance for a deeper understanding of the structure and subsequent calculations. In this study, the scanning electron microscope (SEM) and X-ray microcomputed tomography (µCT) images of a graphite foam sample are used for image analysis method (IAM) and virtual 3D reconstruction as non-destructive scientific tools with high accuracy. The morphological characterization and determination of effective pore diameter, porosity, specific surface area (SSA), and effective thermal conductivity (ETC) of POCO graphite foam are investigated. By examining the results obtained from the method of image analysis, it is found that there is a good agreement among the IAM results

Analisa Ekonomi USAha Peternakan Broiler Yang Menggunakan Dua Tipe Kandang Berbeda

This study aims at analyzing economic calculations of broiler farm activities which applied two different housing systems (closed and opened house system) at Malang Regency. Data were collected from two selected broiler farmers from April 15th to May 11st, 2013. Then the data were analyzed using economic and descriptive method. The results show that farmers who applied closed housing system were able to earn more profit (Rp2.214,-/bird/period) than those who applied opened housing system (Rp1.875,-/bird/period). However, farmers with closed housing system paid higher pro-duction costs than those with the opened housing system. Another findings show that both (closed and opened house) systems were economically viable for broiler production since they provide a good R/C ratio. This study suggests broiler farmers who tend to apply closed housing systems should modify the equipments which require higher costs

Utilization of grass and legume fibre and vegetable oil as dietary supplements on village chicken layer production under free range production system

This study was carried out to determine the effects of fibre (Leucaena – Leucaena leucocephala and Napier grass – Pennisetum purpureum) and vegetable oil sources (linseed oil and palm oil) on the egg production (EP), egg weight (EW), percentage of hen daily average egg production (%HDA), feed intake (FI), and feed conversion ratio (FCR). Hens were divided into five groups. One basal diet (BD) was used in the experiment as control group. There were 4 experimental groups which were supplemented with various sources of fibre and oil as follows: Group1: BD + 5% linseed oil, Group 2: BD + 5% palm oil, Group 3: BD + 5% palm oil plus 2.5% Napier grass and Group 4: BD + 5% linseed oil plus 2.5% Leucaena leaf, respectively. The experiment lasted for 12 weeks. It was observed that there was significant difference (P0.05) was observed on feed conversion ratio (FCR) and feed intake in free range production systems. The lowest feed intake among treatments was belonged to treatment which was included with linseed oil plus Leucaena while the highest feed consumption is from group which was contained palm oil. The highest egg weight among treatments was from treatment which used palm oil plus Napier grass in free range farming system. The highest number of egg production was from treatment contained palm oil plus Napier grass while the lowest egg production was belonged to control group

Excitonic Effects and Optical Spectra of Single-Walled Carbon Nanotubes

Many-electron effects often dramatically modify the properties of reduced dimensional systems. We report calculations, based on an many-electron Green's function approach, of electron-hole interaction effects on the optical spectra of small-diameter single-walled carbon nanotubes. Excitonic effects qualitatively alter the optical spectra of both semiconducting and metallic tubes. Excitons are bound by ~ 1 eV in the semiconducting (8,0) tube and by ~ 100 meV in the metallic (3,3) tube. These large many-electron effects explain the discrepancies between previous theories and experiments.Comment: 6 pages, 3 figures, 2 table

Uniqueness of nontrivially complete monotonicity for a class of functions involving polygamma functions

For $m,n\in\mathbb{N}$, let $f_{m,n}(x)=\bigr[\psi^{(m)}(x)\bigl]^2+\psi^{(n)}(x)$ on $(0,\infty)$. In the present paper, we prove using two methods that, among all $f_{m,n}(x)$ for $m,n\in\mathbb{N}$, only $f_{1,2}(x)$ is nontrivially completely monotonic on $(0,\infty)$. Accurately, the functions $f_{1,2}(x)$ and $f_{m,2n-1}(x)$ are completely monotonic on $(0,\infty)$, but the functions $f_{m,2n}(x)$ for $(m,n)\ne(1,1)$ are not monotonic and does not keep the same sign on $(0,\infty)$.Comment: 9 page

A Reduced Order Model for the Design of Oxy-Coal Combustion Systems

Oxy-coal combustion is one of the more promising technologies currently under development for addressing the issues associated with greenhouse gas emissions from coal-fired power plants. Oxy-coal combustion involves combusting the coal fuel in mixtures of pure oxygen and recycled flue gas (RFG) consisting of mainly carbon dioxide (CO2). As a consequence, many researchers and power plant designers have turned to CFD simulations for the study and design of new oxy-coal combustion power plants, as well as refitting existing air-coal combustion facilities to oxy-coal combustion operations. While CFD is a powerful tool that can provide a vast amount of information, the simulations themselves can be quite expensive in terms of computational resources and time investment. As a remedy, a reduced order model (ROM) for oxy-coal combustion has been developed to supplement the CFD simulations. With this model, it is possible to quickly estimate the average outlet temperature of combustion flue gases given a known set of mass flow rates of fuel and oxidant entering the power plant boiler as well as determine the required reactor inlet mass flow rates for a desired outlet temperature. Several cases have been examined with this model. The results compare quite favorably to full CFD simulation results