201 research outputs found
Heavy quark fragmentation functions at next-to-leading perturbative QCD
It is well-known that the dominant mechanism to produce hadronic bound states
with large transverse momentum is fragmentation. This mechanism is described by
the fragmentation functions (FFs) which are the universal and
process-independent functions. Here, we review the perturbative FFs formalism
as an appropriate tool for studying these hadronization processes and detail
the extension of this formalism at next-to-leading order (NLO). Using the
Suzuki's model, we calculate the perturbative QCD FF for a heavy quark to
fragment into a S-wave heavy meson at NLO. As an example, we study the LO and
NLO FFs for a charm quark to split into the S-wave -meson and compare our
analytic results both with experimental data and well-known phenomenological
models
Synthesis and properties of carboxymethylcellulose (CMC) graft copolymer with on-off switching properties for controlled release of drug
Novel biopolymer-based superabsorbent hydrogels were prepared by grafting crosslinked poly (N-vinyl pyrollidin and 2-Acrylamido-2-methyl propan sulfonic acid (PNVP-co-PAMPS) chains onto CMC backbones through a free radical polymerization method. A proposed mechanism for superabsorbent hydrogel formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The morphology of the samples was examined by scanning electron microscopy (SEM). The concentration of released metronidazole loaded was monitored at 245 nm on the UV spectrophotometer. Water absorption of the hydrogel could be switched on and off swiftly by control of pH of the surrounding environment. Therefore, the synthesized hydrogels in this study can be used as a drug delivery system and that the drug release can be controlled by the pH of solution. The release rate of metronidazole from hydrogel at pH 7.4 was higher than that at pH 1.6, due to the increased swelling capacity of the hydrogel.Key words: CMC, hydrogels, release drug, N-vinyl pyrollidin, 2-acrylamido-2-methyl propan sulfonic acid
Synthesis and characterization of superabsorbent hydrogel based on chitosan-g-poly (acrylic acid-coacrylonitrile)
In this work, acrylonitrile (AN) and acrylic acid (AA) monomers were directly grafted onto chitosan using ammonium persulfate (APS) as an initiator and methylenebisacrylamide (MBA) as a crosslinking agent under an inert atmosphere. The hydrogels structure was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The effect of grafting variables, that is, AA/AN weight ratio and concentration of MBA and APS, was systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The water absorbency increased with increasing the AA amount in the monomer feed due to formation of polyelectrolyte. The swelling of the hydrogel samples in saline solution (0.15 mol/l NaCl, CaCl2 and AlCl3) was examined. The results indicate that the swelling capacity decreased with an increase in the ionic strength of the swelling medium. This behavior can be attributed to charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. Furthermore, the swelling of superabsorbing hydrogels was examined in solutions with pH values ranging between 1 and 13.Key words: Hydrogel, chitosan, superabsorbent, acrylonitrile, acrylic acid
Comparison of Indoor and Outdoor Dose Rates from Environmental Gamma Radiation in Kurdistan Province
Abstract:
Background & Aims: Studying about background radiation is important because human beings are continuously exposed to these radiations which leave energy in tissues and the transferred energy leads to undesirable biologic effects. The level of background radiation differs in indoor and outdoor places. Since, people spend more time indoors, in this research environmental gamma dose rate for indoor and outdoor places of Kurdistan towns was determined and compared.
Methods: To estimate dose rate at outdoors, four stations in the length of main directions and one in the center of each city were selected. To estimate dose rate at indoors, two stations in each town according to the type of buildings were selected. In each station gamma dose rate was measured for one hour by RDS-110 servimeter at one meter height from the earth.
Results: The average of outdoor and indoor environmental gamma dose rate for Kurdistan towns obtained as follows: Baneh 134 (SD=5), 166 (SD=25) nSv/h, Bijar 113 (SD=17), 141 (SD=8) nSv/h, Divandareh 110 (SD=8), 134 (SD=12) nSv/h, Saqez 105 (SD=12), 134 (SD=11) nSv/h, Sanandaj 110 (SD=12), 133 (SD=4) nSv/h, Qorve 114 (SD=20), 160 (SD=4) nSv/h, Kamyaran 92 (SD=4), 115 (SD=14) nSv/h, Marivan 110 (SD=9), 122 (SD=18) nSv/h.
Conclusion: Data shows that indoor dose rates in Baneh (%24), Bijar (%24), Divandareh (%22), Saqez (%28), Sanandaj (%21), Qorveh (%40), Kamyaran (%25) and Marivan (%11) exceed outdoor dose rate in these towns.
Keywords: Environmental gamma, Dose rate, Indoor, Outdoo
The cosmological bulk flow in QCDM model: (In)consistency with
We study the bulk flow of the local universe using Type Ia supernova data by
considering a class of cosmological model which is spatially flat,(FRW)
space-times and contains cold dark matter and component (QCDM models) of
the fluid as a scalar field, with self interactions determined by a potential
evolving in Universe. We use different cumulative
redshift slices of the Union 2 catalogue. A maximum-likelihood analysis of
peculiar velocities confirms that at low redshift , bulk flow is
moving towards the direction with
velocity. This direction is aligned with
direction of (SSC) and agreement with a number previous studies at
, however for high redshift , we get towards the . This indicates that for low redshift our results are
approximately consistent with the model with the latest WMAP best
fit cosmological parameters however for high redshift they are in disagreement
of and support the results of previous studies such as Kashlinsky
et. al, which report the large bulk flow for the Universe. We can conclude
that, in model, at small scales, fluctuations of the dark energy are
damped and do not enter in the evolution equation for the perturbations in the
pressureless matter, while at very large scales , they
leaving an imprint on the microwave background anisotropy
Photometric Stereo with Non-Lambertian Preprocessing and Hayakawa Lighting Estimation for Highly Detailed Shape Reconstruction
In many realistic scenarios, the use of highly detailed photometric 3D reconstruction techniques is hindered by several challenges in given imagery. Especially, the light sources are often unknown and need to be estimated, and the light reflectance is often non-Lambertian. In addition, when approaching the problem to apply photometric techniques at real-world imagery, several parameters appear that need to be fixed in order to obtain high-quality reconstructions. In this chapter, we attempt to tackle these issues by combining photometric stereo with non-Lambertian preprocessing and Hayakawa lighting estimation. At hand of a dedicated study, we discuss the applicability of these techniques for their use in automated 3D geometry recovery for 3D printing
Assessment of pH-responsive nanoparticles performance on laboratory column flotation cell applying a real ore feed
Nanoparticles (NPs) can promote the column flotation process in mining industry. Nanoparticles’ effects on column flotation process (copper recovery, grade and flotation rate constant) are assessed in Sarcheshmeh Copper Complex, Iran, through response surface methodology (RSM) optimization technique. The γ-Al2O3, α-Fe2O3, SiO2, and TiO2 nanoparticles are selected for these experiments. A flotation rate constant is chosen as a response to assess the effect of nanoparticles on flotation in its kinetic sense. The process pH and nanoparticle dosage are selected as the influential parameters. Results obtained from RSM indicated that the maximum percentage of Cu recovery and grade is obtained at pH of 12 and nanoparticle dosage of 6 kg/t, through α-Fe2O3 and γ-Al2O3 nanoparticles, respectively. Applying nanoparticles in particular γ-Al2O3 and α-Fe2O3 increases the Cu recovery by 8–10% together with the grade by 3–6% in a significant manner. It is revealed that nanoparticles could effectively be applied in enhancing the flotation performance
Spatial and temporal trends of short-term health impacts of PM2.5in Iranian cities; A modelling approach (2013�2016)
Estimation of the spatial and temporal trends of health impacts attributable to air pollution is an effective measure for evaluating implemented interventions. The aim of this study was to estimate the short-term mortality attributable to exposure to PM2.5among individuals older than 30 years old in ten Iranian cities from March 2013 to March 2016 using the World Health Organization�s (WHO) AirQ+ software. Hourly concentrations of PM2.5were acquired from the Department of Environment and Tehran Air Quality Control Company. Only stations with 75 and 50 of valid data were qualified for Tehran and other cities, respectively. The annual average PM2.5concentrations in all ten of the cities were higher than the WHO guideline value of 10 µg m�3The total number of attributable short-term deaths during the three-year period in these 10 cities was 3284 (95 CI: 1207�5244). The average daily premature deaths were calculated to be 3. The highest number of premature deaths within the three-year period was estimated to be 548 in Tehran, largely reflecting its population of nearly 9 million. The western and southern cities of Iran experience severe dust storms and showed a high estimated rate of death attributed to air pollution. The health impacts in all cities decreased in the third year compared to the first year except for Ahvaz, Khoram Abad, and Ilam. Governmental interventions need to be enforced more effectively to reduce the high level of adverse health impacts in Iran. Special considerations should be given to the air quality of cities affected by dust storms. © Taiwan Association for Aerosol Research
Design and evaluation of the performance of local exhaust hood on the welding torch
Background and aims: Threats against welders' health due to exposure to welding fume is an important issue; thus, controlling and examining effective exhaust of fumes are necesary. In this study, was evaluated prototype operation of local exhaust ventilation on-gun in bench scale. Methods: Duct velocity average was determined using traverse points method and calculated flow rate by hood using ACGIH standard method. Also capture velocity close in contaminant source (Arc Point) was measured using thermal anemometer. Then, in order to determine total particles concentration and capture efficiency created by system NIOSH 7200 standard method was used. Results: Duct velocity average and created flow rate by evaluated system were 6296.1±92.50 fpm and 34.06±0/50 scfm, respectively. Also, capture velocity in close of the weld point was obtained 140 fpm. Sampling results for averaged total particles concentration in off and on positions of system were 75±7 mg/m3 and 16.7±4 mg/m3, respectively. As a result, 77 containment efficiency was achieved by this system. Conclusion: The local exhaust ventilation used in this study was a low cost prototype and according to the acheived results, it leads to reduce total particles concentration (T.P) in breathing zone aproximately to 22
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