A study of dynamic finite size scaling behavior of the scaling functions—calculation of dynamic critical index of Wolff algorithm

In this work we have studied the dynamic scaling behavior of two scaling functions and we have shown that scaling functions obey the dynamic finite size scaling rules. Dynamic finite size scaling of scaling functions opens possibilities for a wide range of applications. As an application we have calculated the dynamic critical exponent (z) of Wolff's cluster algorithm for 2-, 3- and 4-dimensional Ising models. Configurations with vanishing initial magnetization are chosen in order to avoid complications due to initial magnetization. The observed dynamic finite size scaling behavior during early stages of the Monte Carlo simulation yields z for Wolff's cluster algorithm for 2-, 3- and 4-dimensional Ising models with vanishing values which are consistent with the values obtained from the autocorrelations. Especially, the vanishing dynamic critical exponent we obtained for d=3 implies that the Wolff algorithm is more efficient in eliminating critical slowing down in Monte Carlo simulations than previously reported.     

Effect of Valsalva Maneuver on QT Dispersion in Hemodialysis Patients

Increased QT dispersion seems to be related to an increased risk of arrhythmia and sudden death, a common cause of mortality in hemodialysis (HD) patients. Increase in sympathetic tone has been documented in HD patients. In this study, we aimed to investigate the effect of changes in the autonomic tone on QT dispersion (QTd) in HD patients. Twenty HD patients (M/F 13/7; age, mean ±SD, 28 ± 10 years) and 22 age‐ and sex‐matched healthy controls (M/F 12/10; age, 30 ± 10 years) were included. The patients were dialyzed three‐times weekly; time on dialysis was 17 ± 8 months. The QT durations were measured from 12 lead surface EKGs and were corrected for RR intervals. Corrected maximum (QT_c max) and minimum (QT_cmin) QT intervals and their difference (QT _c d) were recorded. The effect of the Valsalva maneuver in the release phase on QT _c intervals and dispersion was assessed. The HD patients had prolonged values compared to controls: QT _c d, 59 ± 17 ms versus 35 ± 7 ms, p < 0.001; QT _c max, 458 ± 41 ms versus 397 ± 21 ms, p < 0.001; and QT _c min, 398 ± 36 ms versus 362 ± 25 ms, p < 0.001. After the Valsalva maneuver no changes were observed in controls: QT _c max, 397 ± 21 ms versus 396 ± 22 ms, p = 0.9; QT _c min, 362 ± 24 ms versus 358 ± 19 ms, p = 0.5; and QT _c d, 35 ± 7 ms versus 38 ± 10 ms, p = 0.15. Whereas, in HD patients all values were significantly shortened: QT_cmax, 458 ± 41 ms versus 427 ± 35 ms, p = 0.003; QT_c min, 398 ± 36 ms versus 379 ± 34 ms, p = 0.04; and QT_c d, 59 ± 17 ms versus 48 ± 15 ms, p = 0.01. The decrease in QTmax was more prominent than the decrease in QTmin, hence QT dispersion was significantly decreased after the Valsalva maneuver, but differences from controls were still significant. In conclusion, increased sympathetic activity may have a role in the prolonged QT duration and increased QT dispersion in HD patients.     

Effects of steaming process on some properties of eucalyptus particleboard bonded with UF and MUF adhesives

The steaming process, applied to logs before chipping, affected positively the dimensional stability of eucalyptus particleboard whereas, the internal bonding. The modulus of rupture (MOR) and internal bond strength (IB) values of the panels produced from steamed log parts without hardener were found to be higher than those of the panels produced by adding hardener into the urea formaldehyde (UF) glue. The steaming process did not have a clear effect on the IB of the panels bonded with melamine–urea formaldehyde (MUF) resin. The IB values of the panels bonded with MUF resin were higher than those of the panels bonded with UF resin. The MOR values of the MUF-bonded panels were higher than the requirement for general purpose panels. The steaming process caused an extra improvement in the thickness swelling (TS) of the panels bonded with MUF resin, which has higher resistance to water and weather than UF resin. The TS of the panels produced without hardener was half of the value obtained for the panels bonded with hardener-added UF resin.     

A dimensionless analysis of heat and mass transport in an adsorber with thin fins; uniform pressure approach

A numerical study on heat and mass transfer in an annular adsorbent bed assisted with radial fins for an isobaric adsorption process is performed. A uniform pressure approach is employed to determine the changes of temperature and adsorbate concentration profiles in the adsorbent bed. The governing equations which are heat transfer equation for the adsorbent bed, mass balance equation for the adsorbent particle, and conduction heat transfer equation for the thin fin are non-dimensionalized in order to reduce number of governing parameters. The number of governing parameters is reduced to four as Kutateladze number, thermal diffusivity ratio, dimensionless fin coefficient and dimensionless parameter of Γ which compares mass diffusion in the adsorbent particle to heat transfer through the adsorbent bed. Temperature and adsorbate concentration contours are plotted for different values of defined dimensionless parameters to discuss heat and mass transfer rate in the bed. The average dimensionless temperature and average adsorbate concentration throughout the adsorption process are also presented to compare heat and mass transfer rate of different cases. The values of dimensionless fin coefficient, Γ number and thermal diffusivity ratio are changed from 0.01 to 100, 1 to 10^− 5 and 0.01 to 100, respectively; while the values of Kutateladze number are 1 and 100. The obtained results revealed that heat transfer rate in an adsorbent bed can be enhanced by the fin when the values of thermal diffusivity ratio and fin coefficient are low (i.e., α^? = 0.01, Λ = 0.01). Furthermore, the use of fin in an adsorbent bed with low values of Γ number (i.e. Γ = 10^− 5) does not increase heat transfer rate, significantly.     

NATURAL ZEOLITES IN AIR DRYING

ABSTRACT

The local clinoptilolite from Bigadis region in Turkiye, was used for air drying in packed column. The effective diffusion coefficient of water in natural zeolite was found as 5×10^?10 m² s^?1 from isothermal uptake measurements. Effects of packing height and airvelocity on breakthrough curves were studied.     

Nanoscopic investigation on TiO2-SiO2-GLYMO nanocomposite coated and plasma treated leathers

ABSTRACT

In this study, the modification of leather surface by application of TiO₂-SiO₂-GLYMO (3-Glycidyloxypropyltrimethoxysilane) nanocomposite coating and plasma treatment with N₂ gas activation is investigated by using Small and Wide Angle X-ray scattering methods. The protective properties were tried to be developed with TEOS and HMDSO polymers’ usage in the coating process by following and controlling nano scale structural changes. The main aim was the controls of nanoscaled surface modifications and determination of the best coating process by keeping natural structure of the leathers. These scattering methods were useful to investigate the coating effects on the PTLs (Plasma Treated Leathers)’ internal structures including collagen microfibers and nanofibers which are hierarchical structures of triple helix collagen. The main purpose of the work was investigate whether the structural change in the natural form of the leather is present or not in the molecular-nanoscopic and microscopic scales after the coating and the applied physico-bio-chemical processes. On the other hand, the successful protective coatings and surface modifications were determined with SAXS analyses by controlling the shape, size and distance distributions of the appeared nanoglobular aggregations. The observations of structural changes taking place within collagen fibrils as a result of surface modification provides new insight into the nature of finishing and informs future processing developments.     

Dynamics of electrospinning of poly(caprolactone) via a multi‐nozzle spinneret connected to a twin screw extruder and properties of electrospun fibers

Conventional electrospinning is a simple process, suitable for the processing of solvated polymers at relatively low rates. It lacks the capabilities of conveying of solids, mixing of polymeric resins and devolatilization and has limited capabilities in melting and incorporation of fillers, including nanoparticles. The use of a twin screw extruder as the front end of the electrospinning process provides these capabilities but only becomes feasible at relatively high throughput rates. Such high rates of electrospinning can only be achieved by using multi‐nozzle spinnerets. However, the dynamics of electrospinning processes using multi‐nozzle spinnerets has not been well studied. Here a multi‐nozzle spinneret attached to a hybrid twin screw extrusion and electrospinning apparatus was employed for the characterization of the dynamics in terms of the electrospun mesh thickness distributions of poly(caprolactone), PCL, as a function of the principal parameters of the electrospinning process, i.e., applied voltage, distance of separation between the spinneret die, and the collector, i.e., a conductive mandrel, and its rotational speed. PCL fiber diameter and orientation distributions, as well as the thickness, crystallinity, and mechanical properties of the non‐woven meshes, were characterized to gain a basic understanding of how the electrospun mesh properties develop as a function of process parameters in the multi‐nozzle configuration. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Biosorption properties of dried Neurospora crassa for the removal of Burazol Blue ED dye

Biosorption potential of dried Neurospora crassa for Burazol Blue ED was studied with respect to pH, equilibrium time, biomass concentration and temperature to determine equilibrium and kinetic model parameters. The most suitable pH, equilibrium time and biomass concentration were determined as 1 ± 0.2, 60 min and 1.6 g L^− 1, respectively, at 20 °C ± 1.0. The equilibrium data was best described by the Langmuir isotherm model. The maximum biosorption capacity (q_m) of biomass obtained from the Langmuir fit was 110.1 mg g^− 1 biomass at 30 °C. The overall biosorption process was best described by the pseudo-second-order kinetic model. The biosorption process was found to be favored at higher temperatures.     

Experimental and theoretical study of the effect of some heterocyclic compounds on the corrosion of low carbon steel in 3.5% NaCl medium

The efficiency of three heterocyclic compounds, 3-amino-1,2,4-triazole, 4-hydroxy-2H-1-benzopyran-2-one and 4-hydroxy-3-(1H-1,2,4-triazole-3-ylazo)-2H-1-benzopyran-2-one (abbreviated 3-ATA, 4-HQ and 3-ATA-Q, respectively) as steel corrosion inhibitors in 3.5% NaCl has been investigated by Tafel extrapolation and linear polarization methods. Corrosion parameters and adsorption isotherms were determined from current-potential curves. It was found that inhibition efficiencies (η%) and surface coverage (θ) increase with an increase in the concentration of 3-ATA and 3-ATA-Q. However, 4-HQ accelerates the corrosion rate as its concentration increases. The adsorption of 3-ATA and 3-ATA-Q on the steel surface obey Langmuir isotherm. A clear correlation was found between corrosion inhibition efficiency and theoretical parameters obtained by the density functional B3LYP/6-31g(d) method. The experimental results are supported by the theoretical data.