Thermal conductivity and stability of carbon nanotube (CNT) structures in water-based nanofluid, as well as their dependence to temperature and time variation are of a great concern. In order to ...investigate such dependence, five different structures, namely SWNT (single wall CNT), DWNT (double wall CNT), FWNT (few wall CNT) and two different multiwalls were applied in this study. The experiments reveal that the maximum UV–VIS absorbance of the solution corresponds to the dispersion of SWNT in the base fluid. The results from zeta size distribution and thermal conductivity demonstrate that as the number of nanotube wall increase, both stability and thermal conductivity decrease.
Forced convective of a nanofluid that consists of water and Al
2O
3 in horizontal tubes has been studied numerically. Computed results were validated with existing well established correlation. ...Two-phase Eulerian model has been implemented for the first time to study such a flow field. A single-phase model and two-phase mixture model formulations were also used for comparison. The comparison of calculated results with experimental values shows that the mixture model is more precise. It is illustrated that the single-phase model and the two-phase Eulerian model underestimates the Nusselt number. Effects of nanoparticles concentration on the thermal parameters are also discussed.
Nanocrystalline nickel coating was synthesized by direct current electrodeposition from a Watts bath at the current density of 100
mA/cm
2 and pH
=
4. The effect of saccharin addition (0–10
g/l) and ...bath temperature (45–65
°C) on the average grain size of the deposits was investigated by XRD technique. The results showed that the average grain size decreased from 426
nm to 25
nm as the saccharin concentration increased from 0 to 3
g/l, while further increase in saccharin concentration had no significant effect. Theoretical model also indicated a non-linear function for dependence of grain size on saccharin concentration, which was in accordance with experimental results. The experimental results showed that the increases in the bath temperature had no considerable effect on the average grain size of the deposits. A theoretical formula was also established for the temperature dependence of the grain size.
The aim of this work was to investigate the effect of current density on the grain size of electrodeposited nickel coatings. For this purpose, nanocrystalline nickel coatings were deposited from a ...Watts bath containing 5 g/l sodium saccharin as an additive, by direct current electroplating at different current densities. X-ray diffraction analysis and modified Williamson–Hall relation were used to determine the average grains size of the coatings. The experimental results showed that the coating grains size decreased sharply by increasing the current density from 10 mA/cm
2 to 75 mA/cm
2. Nanocrystalline nickel coating with average grain size smaller than 30 nm can be achieved at the current densities higher than 50 mA/cm
2. Furthermore, a general and simple theoretical model based on atomistic theory of electrocrystallization has been made in order to find out the relationship between the grain size and current density. According to this model the variation of log (d) versus log (i) was linear which is in accordance with experimental results for the current densities lower than 75 mA/cm
2.
► All thermophysical properties of alumina nanofluids have been measured experimentally. ► Tow correlations for calculating the thermal conductivity and dynamic viscosity of nanofluids have been ...proposed. ► The Al2O3–water nanofluids have been produced by a two step method. ► Convective transport of nanofluids has been studied in fully developed region under the constant wall temperature. ► Traditional correlations failed to predict the Nusselt number and pressure drop of the nanofluids.
This article presents the heat transfer coefficient and friction factor of the nanofluids flowing in a horizontal tube under laminar flow conditions, experimentally. The experiments have been done on fully developed region under the constant wall temperature condition. Al2O3 nanoparticles with diameters of 40nm dispersed in distilled water with volume concentrations of 0.1–2vol.% were used as the test fluid. All physical properties of the Al2O3–water nanofluids needed to calculate the pressure drop and the convective heat transfer coefficient have been measured. The results show that the heat transfer coefficient of nanofluid is higher than that of the base fluid and increased with increasing the Reynolds number and particle concentrations. The heat transfer coefficient increases by approximately 32% in the fully developed region at 2vol.% nanofluid. The measured pressure loss for the nanofluids was in general much higher than for pure water. The experimental results illustrate that the single phase correlation with nanofluids properties could not predict heat transfer coefficient enhancement of nanofluids fairly.
Allogeneic stem cell transplantation (allo-SCT) outcomes in patients with Hodgkin lymphoma (HL) remain poorly defined. We performed a meta-analysis of allo-SCT studies in HL patients. The primary ...endpoints were 6-month, 1-year, 2-year and 3-year relapse-free survival (RFS) and overall survival (OS). A total of 42 reports (1850 patients) was included. The pooled estimates (95% confidence interval) for 6-month, 1-year, 2-year and 3-year RFS were 77 (59-91)%, 50 (42-57)%, 37 (31-43)% and 31 (25-37)%, respectively. The corresponding numbers for OS were 83 (75-91)%, 68 (62-74)%, 58 (52-64)% and 50 (41-58)%, respectively. There was statistical heterogeneity among studies in all outcomes. In meta-regression, accrual initiation year in 2000 or later was associated with higher 6-month (P=0.012) and 1-year OS (P=0.046), and pre-SCT remission with higher 2-year OS (P=0.047) and 1-year RFS (P=0.016). In conclusion, outcomes of allo-SCT in HL have improved over time, with 5-10% lower non-relapse mortality and relapse rates, and 15-20% higher RFS and OS in studies that initiated accrual in 2000 or later compared with earlier studies. However, there is no apparent survival plateau, demonstrating the need to improve on current allo-SCT strategies in relapsed/refractory HL.
Palladium nanocatalysts supported on reduced graphene oxide (rGO), multi walled carbon nanotubes (MWCNT), and rGO/CNT composite were synthesized by a wet impregnation method using PdCl2 as a ...precursor. Palladium loading was 0.3 wt %, and the catalysts were reduced at 300 °C. The catalysts were characterized by inductively coupled plasma, Brunauer−Emmett−Teller (BET) analysis, Fourier transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, temperatue-programmed reduction, temperatue-programmed desorption, and Raman spectroscopy. The performance of the catalysts was investigated for hydro-purification of crude terephthalic acid (CTA) containing 2100 ppm 4-carboxybenzaldehyde (4-CBA) as an impurity. The reaction products were analyzed by HPLC to determine the amounts of 4-CBA, benzoic acid, and p-toluic acid. Pd/rGO–CNT catalyst had excellent performance in terms of both selectivity and 4-CBA conversion. All catalysts exhibited more than 99% removal of 4-CBA. The most desired selectivity, however, was obtained for the catalyst with rGO–CNT as a support. Comparison with the performance of the commercial catalyst (0.5 wt % palladium on activated carbon) indicated that the Pd/rGO–CNT catalyst had a better performance.
Population structure and genetic diversity are the key parameters to study the breeding history of animals. This research aimed to provide a characterization of the population structure and to ...compare the effective population size (Ne), LD decay, genetic diversity, and genomic inbreeding in Iranian native Caspian (n = 38), Turkmen (n = 24) and Kurdish (n = 29) breeds and some other exotic horses consisting of Arabian (n = 24), Fell pony (n = 21) and Akhal-Teke (n = 20). A variety of statistical population analysis techniques, such as principal component analysis (PCA), discriminant analysis of principal component (DAPC) and model-based method (STRUCTURE) were employed. The results of the population analysis clearly demonstrated a distinct separation of native and exotic horse breeds and clarified the relationships between studied breeds. The effective population size (Ne) for the last six generations was estimated 54, 49, 37, 35, 27 and 26 for the Caspian, Kurdish, Arabian, Turkmen, Akhal-Teke and Fell pony breeds, respectively. The Caspian breed showed the lowest LD with an average r2 value of 0.079, while the highest was observed in Fell pony (0.148). The highest and lowest average observed heterozygosity were found in the Kurdish breeds (0.346) and Fell pony (0.290) breeds, respectively. The lowest genomic inbreeding coefficient based on run of homozygosity (FROH) and excess of homozygosity (FHOM) was in the Caspian and Kurdish breeds, respectively, while based on genomic relationship matrix) FGRM) and correlation between uniting gametes) FUNI) the lowest genomic inbreeding coefficient was found in the Kurdish breed. The estimation of genomic inbreeding rates in the six breeds revealed that FROH yielded lower estimates compared to the other three methods. Additionally, the Iranian breeds displayed lower levels of inbreeding compared to the exotic breeds. Overall, the findings of this study provide valuable insights for the development of effective breeding management strategies aimed at preserving these horse breeds.
Bimetallic copper-clad steel rod was prepared via three successive passing the samples through equal-channel angular pressing (ECAP) die with route Bc. The core steel tensile properties and ...copper/steel interface microstructures were investigated after each passes. It is observed the yield strength of steel core increased from about 200 MPa to 840 MPa and equiaxed grains with the size lower than the one-third of the initial size were formed. Only, during the third passing of ECAP deformation, the copper/steel interface was changed to waveforms in some angular positions. The shear strain and mating surface stretch were modeled to explain this phenomenon.
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