Values Of kL Research Articles

Comparative adsorptive behaviour of cow dung ash and starch as potential eco-friendly matrices for controlled organophosphorus pesticides delivery

The work reported herein explores the viability of cow dung ash (CDA) as a matrix for controlled pesticide delivery, by comparing its adsorptive characteristics towards two organophosphorus pesticides with those of starch, conventionally utilized in designing controlled pesticide delivery systems. CDA was characterized by Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD). Data for pesticide adsorption on the surfaces correlate well with Langmuir and Freundlich isotherms, with the former isotherm giving a slightly better fit (R2 ≥ 0.90) than the latter (R2 ≥ 0.81). Values of the adsorption parameters KL and RL indicate favourable pesticide adsorption on both surfaces. Desorption is the microscopic reverse of adsorption; both processes obey pseudo-second-order kinetics. The implication of this kinetic form is a mechanism in which adsorbate diffusion to the polymer surface and its transport into the polymer interior are important events. The isothermal and kinetic ratios, frac{{K_{L}^{CDA} }}{{K_{L}^{Starch} }} = 3.8 and 4.0, frac{{k_{2}^{CDA} }}{{k_{2}^{Starch} }} = 1.3 and 0.6, and frac{{k_{ - 2}^{CDA} }}{{k_{ - 2}^{Starch} }} = 5.2 and 1.0 at pH 7.0 and 27 °C, compare the adsorptive behaviour of diazinon and dichlorvos, respectively, on CDA and starch. These parameters are of the same order of magnitude, signalling that CDA is as potentially viable as starch for use as a matrix for pesticide-controlled delivery.

Potassium Mobility Potential of Forest Soil In Kurdistan Region, Iraq, As Estimated By Quantity- Intensity (Q/I) Relationships

This study aimed to assess potassium(K) 's potential mobility for some soils located in the Kurdistan Region of Iraq. Five soil samples were collected from a depth of (0-30) cm. For each sample, 5g of soil was equilibrated with 50 ml of 0.01 M CaCl2, amended with different K concentrations, and incubated for 24 h at 298 Kelvin. The supernatant was filtered, and K, Ca, and Mg were determined. Potassium exchange equilibrium was calculated from quantity-intensity (Q/I) isotherms. Mean AReK values for all studied soils ranged between 2.4x10-3 to 3.6x10-3(mol L-1)1/2, which reveals that K was preferentially held at inner potions. The amount of labile K(KL) ranged from 0.479 to 1.191cmolc kg-1 in studied soils. The highest value of KL was in Kanypanka while the lowest value was in Goizha. The potential buffering capacity (PBCK) was between 619.56 and 857.37 cmolc kg-1(mol L-1) -1/2. All studied soils were characterized by low percent K saturation and a high ability to replenish K concentration in the soil solution. Gapon selectivity coefficient was relatively high and ranged from 5.64 to 7.88 L mol-1. Higher values of KL indicate a greater K release into the soil solution. Such a high affinity of K for the solid soil phase was attributed to both the elevated organic matter content in these soils and their strong buffering capacities.

Numerical solution of the Burgers equation associated with the phenomena of longitudinal dispersion depending on time

In this study, the Burgers equation governing the time-dependent dispersion phenomena is solved numerically using the finite difference scheme and the Runge-Kutta 4 algorithm with appropriate initial and boundary conditions. Two time-dependent dispersion functions have been implemented to analyze the spatio-temporal variation in the domain. For the values of KL and KA < 1.2 years, a significant retention of the mass of solute is observed when the dispersion function is asymptotic. The results obtained show that the concentration profiles are similar when the values of KL and KA ≥ 1.2 years. These results demonstrate the importance of the nature of the dispersion function on the retention capacity of solutes in the porous medium.

MO640: Treatment with Sodium–Glucose Cotransporter 2 Inhibitors Increases Klotho in Type 2 Diabetic Patients

Abstract BACKGROUND AND AIMS Klotho (KL) is a transmembrane protein mainly expressed by the tubular cells of the kidneys, with an additional soluble form that is present in blood and urine. Preserved KL has been related to physiological protection of the kidneys. Sodium–glucose cotransporter type-2 inhibitors (SGLT2i) are a new class of anti-diabetic drugs with important renal benefits. The aim of the present study was to analyze the effect of treatment with SGLT2i on soluble KL concentrations as well as on mRNA expression levels of the KL gene in renal tubular cells. METHOD Fifty-seven patients (30 males and 27 females; mean age 61 ± 5 years) with type 2 diabetes and chronic kidney disease stage G2-A2, all treated with metformin and blockers of the renin–angiotensin system, were included in the study. All patients were in need of intensified anti-diabetic therapy at the discretion of their physicians in accordance with the routine clinical practice. Forty-five received SGLT2i during 3 months (15 empagliflozin, 15 canagliflozin and 15 dapagliflozin), and the evolution was compared with a group of 12 patients matched by age, sex and stage of CKD who received DPP4 inhibitors (control group). Serum and urine levels of soluble KL and tumor necrosis factor-alpha (TNFa) were determined by ELISA. In addition, the effect on mRNA expression levels of KL was assessed in vitro in renal tubular cells cultures. RESULTS Baseline values of serum and urinary KL and TNFa were similar in both groups. Urinary KL was inversely correlated with albuminuria (r = −0.45, P &amp;lt; 0.001) and urine TNFa excretion (r = −0.40, P &amp;lt; 0.01). At the end of the study, there was a similar improvement in metabolic control in both groups; however, only patients treated with SGLT2i showed a significant reduction in albuminuria and urinary TNFa (P &amp;lt; 0.01). Serum and urinary KL increased by 5.2% and 38.9%, respectively, only in patients receiving SGLT2i (P &amp;lt; 0.001 versus baseline), without changes in controls (P &amp;lt; 0.01 between groups). There were no differences among the three drugs in the SGLT2i group. The reduction in albuminuria (β = −0.35, P &amp;lt; 0.01) and urinary TNFa (β = −0.57, P &amp;lt; 0.001) were independently associated with the increase in urine KL, while the change in albuminuria was related to the increase in serum KL (β = −0.39, P &amp;lt; 0.05). Cultured renal tubular cells under high glucose, inflammatory stimulus with TWEAK or serum bovine albumin decreased Klotho mRNA and protein expression within 24 h, an effect that was prevented by all the SGLT2i when added to the cultures. CONCLUSION In type 2 diabetic patients, treatment with SGLT2i induces a reduction in albuminuria and modulates inflammation (as reflected by a decrease in the urinary excretion of TNFa), which is associated with a significant increase in soluble KL concentrations. In addition, SGLT2i prevent the reduction in protein and mRNA expression levels of the KL gene in renal tubular cells. The preservation of KL by SGLT2i may be an important mechanism of renal protection.

Elucidation the influence of design variables on coagulation–flocculation mechanisms in the lab-scale bio-coagulation on toxic industrial effluent treatment

Bio-coagulants are environmentally friendly substances that have shown potential in removing organic and inorganic contaminants from wastewater from the Imitation Paint Industry. Under the optimized conditions, the use of the three bio-coagulants (of plant origin), Strychnos potatorum, Cactus opuntia and Portunus sanguinolentus (crab) shell (of animal origin) were evaluated, and their removal mechanism was based on kinetic models and adsorption isotherms. The error analysis method was used to find the best isotherm fit. In addition, the kinetic model parameters showed the absence of chemisorption and confirmed the existence of pore diffusion. The interaction between coagulant and pollutant, the type, homogeneity and intensity of the coagulation process, the pollutant absorption capacity of the coagulant were evaluated with the aid of the adsorption isotherm models. From the Pseudo first-order kinetic model an equilibrium pollutant uptake (mg/g) was marked as 598, 554 and 597 for Strychnos potatorum, Cactus opuntia and Portunus sanguinolentus respectively. The better affinity between the pollutants and the bio coagulants were observed through the lower values of Langmuir isotherm constant kL. The adsorption intensity from Freundlich model (nF) were ranged between 1 and 10 for all the listed coagulants, which revealed the physisorption behavior and heterogeneous mechanism of removal. With these results, it would be possible to conduct scale-up studies to adopt the process for practical systems.

Improving CO2 mass transfer in microalgal cultures using an oscillatory flow reactor with smooth periodic constrictions

Although very promising, the use of microalgae for CO2 capture still faces some limitations. Due to the low solubility of this gas in the liquid medium, poor CO2 utilisation efficiencies by microalgae are very common, resulting in low CO2 fixation rates and CO2 losses to the atmosphere. Considering this limitation, several researchers have focused on improving photobioreactor (PBR) design to increase CO2 gas-liquid mass transfer rates. However, these systems typically rely on high fluid turbulence and power consumption due to CO2 gas compression. As an alternative, this study proposes using an oscillatory flow reactor with smooth periodic constrictions (OFR-SPC). So far, this reactor design has been successfully applied to improve the mixing efficiency of several chemical processes. However, there is no evidence of its use for microalgal cultivation. To evaluate its potential for microalgal biomass production, a detailed characterisation of CO2 mass transfer was performed. CO2 mass transfer and bubbles’ dynamics were evaluated under different operational conditions: (i) oscillation amplitude and frequency; (ii) aeration rate; (iii) CO2 concentration in the inlet gas; and (iv) biomass concentration. This study made it possible to understand the effect of each process variable on the individual values of liquid-side mass transfer coefficient, kL, and specific interfacial area, a. According to the results, CO2 gas-liquid mass transfer was enhanced by increasing the oscillatory movement, aeration rate and CO2 concentration. Moreover, this study demonstrated that promising CO2 mass transfer rates can be achieved without significantly increasing power consumption and fluid turbulence.

Mass-transfer kinetics of CO2 in a hybrid choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water absorbent

Understanding the mass-transfer kinetics of CO2 in novel hybrid absorbents with physical and chemical contributions is essential for process design and evaluation. In this study, the liquid-side mass-transfer coefficients (kL) and second-order reaction rate constants (k2) of CO2 in hybrid absorbents (namely, choline-2-pyrrolidine-carboxylic acid salt/polyethylene glycol/water ([Cho][Pro]/PEG200/H2O)) were determined. The kL values for the hybrid absorbents were obtained from the CO2 diffusion coefficients (DCO2) and the kL values in PEG200/H2O. The DCO2 value was calculated from the density and viscosity of the hybrid absorbents, whereas the kL values in PEG200/H2O were measured experimentally. The k2 values of CO2 in the hybrid absorbents were estimated according to the reaction mechanism, the enhancement factor, and the kL values, and compared with those of other commercialized absorbents. The results showed that 30 wt% [Cho][Pro] + 70 wt% H2O had the highest kL and k2 values at atmospheric pressure, whereas the values of kL and k2 of CO2 in 30 wt% [Cho][Pro]/H2O + PEG200 were comparable to those in diethanolamine aqueous and amino-functionalized ILs. The hybrid absorbent of [Cho][Pro]/PEG200/H2O could be promising for CO2 separation considering its thermodynamic and kinetic properties.

Equivalent SDOF Load Transformation Factors for One-Way Members Subjected to Air Blast Loading

The equivalent single-degree-of-freedom (SDOF) load transformation factor expressions of the simply supported, fixed end and simply-fixed one-way members subjected to air blast loading are derived by finite series-expansion method or finite point-fitting method. Moreover, figures are used to show the relative relationship between the load transformation factors KL and the ratio of stand-off distance to structural span (γ). The typical calculation conditions show that the load transformation factors are sensitive to the piecewise function of peak overpressure when γ is less than 0.5. The load transformation factor will be a smooth curve for peak overpressure adopting a single smooth continuous function. For the blast-resistant structural design, if the error of 3% in the elastic stage and 5% in the plastic stage can be allowed, γ = 1.0 is the demarcation point between near field blast and far field blast. In addition, if the error of 0.5% can be allowed, γ ≥ 2.0 can be treated as the far field blast. The calculation results of far field blast show that the values of KL of simply supported, simply-fixed, and fixed-end members are 0.64, 0.58, and 0.54, respectively, which means that the load transformation factor is insensitive to the selection of shape function in vibration mode function or static deflection curve function. The calculation accuracy of KL expression for simply supported beam structure in this paper has been verified through near field blast experiments. This paper provides a clear numerical definition for the distinction between near field and far field explosions. It provides qualification criteria for analyzing explosion categories in blast-resistant structural design and a reference for the selection of theoretical calculation formulas.

Gas–Liquid Mass Transfer around a Rising Bubble: Combined Effect of Rheology and Surfactant

The influence of viscosity and surface tension on oxygen transfer was investigated using planar laser-induced fluorescence with inhibition (PLIF-I). The surface tension and the viscosity were modified using Triton X-100 and polyacrylamide, respectively. Changes in the hydrodynamic parameters of millimetric bubbles were identified, and transfer parameters were calculated. The results revealed a decrease in the mass transferred in the presence of a contaminant. For modified viscosity, the decrease in mass transferred was allowed for by current correlations, but the presence of surfactant led to a sharp decrease in the liquid side mass transfer coefficient, which became even lower when polymer was added. An explanation for the gap between classical correlations and experimental values of kL is discussed, and a hypothesis of the existence of an accumulation of contaminant in the diffusion layer is proposed. This led to the possibility of a decrease in the diffusion coefficient and oxygen saturation concentration in the liquid film, explaining the discrepancy between models and experience. Adapted values of DO2 and [O2] * in this layer were estimated. This original study unravels the complexity of mass transfer from an air bubble in a complex medium.

Zirconium-Ferrite Nanoparticles As Improved Adsorbent for Co2+, Cu2+, and Zn2+: Thermodynamic and Kinetic Studies

Nanostructured zirconium ferrite with improved surface area of 392 m2/g has been found to show high adsorption affinity for Co2+, Cu2+, and Zn2+. The adsorption was found to be greatly dependent on pH and the maximum adsorption was found at pH 6. The adsorption trends were found to be best fitted with Langmuir adsorption isotherm with regression coefficient (R2) value of 0.999, 0.998, and 0.999 for Co2+, Cu2+, and Zn2+, respectively, at 288 K. The values of Xm and KL were calculated and showed the maximum adsorption capacities towards Cu2+ and minimum adsorption of Co2+ under the optimized pH, contact time, concentration of adsorbate, adsorbent dose, and temperature. The values of thermodynamic parameters ΔH°, ΔS°, and ΔG° were calculated and showed that the adsorption of Co2+, Cu2+, and Zn2+ on ZFNPs takes place through weak van der Waals interaction. Further, the adsorption of Co2+, Cu2+, and Zn2+ on ZFNPs was found to follow the pseudo–second–order kinetics.

Potassium Mobility Potential of Forest Soil In Kurdistan Region, Iraq, As Estimated By Quantity- Intensity (Q/I) Relationships

This study aimed to assess potassium(K) 's potential mobility for some soils located in the Kurdistan Region of Iraq. Five soil samples were collected from a depth of (0-30) cm. For each sample, 5g of soil was equilibrated with 50 ml of 0.01 M CaCl2, amended with different K concentrations, and incubated for 24 h at 298 Kelvin. The supernatant was filtered, and K, Ca, and Mg were determined. Potassium exchange equilibrium was calculated from quantity-intensity (Q/I) isotherms. Mean AReK values for all studied soils ranged between 2.4x10-3 to 3.6x10-3(mol L-1)1/2, which reveals that K was preferentially held at inner potions. The amount of labile K(KL) ranged from 0.479 to 1.191cmolc kg-1 in studied soils. The highest value of KL was in Kanypanka while the lowest value was in Goizha. The potential buffering capacity (PBCK) was between 619.56 and 857.37 cmolc kg-1(mol L-1) -1/2. All studied soils were characterized by low percent K saturation and a high ability to replenish K concentration in the soil solution. Gapon selectivity coefficient was relatively high and ranged from 5.64 to 7.88 L mol-1. Higher values of KL indicate a greater K release into the soil solution. Such a high affinity of K to the solid soil phase was attributed to both the elevated organic matter content in these soils and their strong buffering capacities.

P1008THERAPY WITH SODIUM-GLUCOSE COTRANSPORTER TYPE 2 INHIBITORS INCREASES KLOTHO IN TYPE 2 DIABETIC PATIENTS

Abstract Background and Aims Klotho (KL) is a transmembrane protein that is expressed the highest in the tubular cells of the kidneys. In addition to membrane KL, a secreted form of this protein that is present in blood and urine is generated by ectodomain shedding of membrane KL from the cell surface or from the KL gene through alternative splicing. Preserved KL expression has been related to physiological protection in the human kidneys. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a new class of antidiabetic drugs with important renal benefits. The aim of the present proof-of-concept study was to analyze if treatment with SGLT2i is associated with changes in soluble KL concentrations as well as with modifications in mRNA expression levels of the KL gene in renal tubular cells. Method Thirty-four patients (18 males and 16 males; mean age 61±5 years) with type 2 diabetes (mean diabetes time higher than 10 years) and CKD G2-A2, all treated with metformin and blockers of the renin-angiotensin system during more than one year, were included in the study. Twenty-four of them received SGLT2i during 6 months (8 empagliflozin, 8 canagliflozin, 8 dapagliflozin), and their data and evolution were compared with a group of 10 patients matched by age, sex and stage of CKD who received sulfonylureas or DPP4 inhibitors. Serum and urine levels of soluble KL and tumor necrosis factor-alpha (TNFa) were determined by ELISA. In addition, the effect of SGLT2i on mRNA expression levels of KL was assessed in vitro in renal tubular cells cultures. Results Baseline median values of serum and urinary KL and TNFa were similar in both groups. Urinary KL was inversely correlated with albuminuria and TNFa excretion (r = -0.39 and r = -0.37, respectively, P&amp;lt;0.05). There were no relationship between the serum and urinary levels of these molecules, suggesting their renal origin. At the end of the study, there was a similar improvement in metabolic control, with a reduction in blood pressure significantly higher in patients treated with SGLT2i. Estimated glomerular filtration rate and albuminuria decreased by 5.8% and 17%, respectively, in subjects receiving SGLT2i (P&amp;lt;0.0001), without changes in the control group. In patients under SGLT2i therapy there was a 21% significant reduction in urinary TNFa with a concomitant 41% increase in urinary KL (P&amp;lt;0.001); there was also a small but significant rise in serum KL (P&amp;lt;0.01 vs baseline). Partial correlation analysis showed that the changes in the urinary excretion of albumin and TNFa were associated with the variation in urinary KL after controlling for other variables (r = -0.50, P&amp;lt;0.01, and r = -0.41, P&amp;lt;0.05, respectively). Finally, renal tubular cells cultured with dapagliflozin showed a significant and dose-dependent increase of mRNA expression levels of KL. Conclusion Treatment with SGLT2i induces a reduction in albuminuria and modulates inflammation (as reflected by a decrease in the urinary excretion of TNFa), which is associated with a significant increase in soluble KL concentrations as well as mRNA expression levels of the KL gene. The preservation of KL by SGLT2i may be an important mechanism of renal protection in type 2 diabetes.

Removal of Cadmium (II) using water hyacinth (Eichhornia crassipes) biochar alginate beads in aqueous solutions

Biochar produced from water hyacinths (Eichhornia crassipes) has been demonstrated to be an effective adsorbent for the removal of certain heavy metals and as a means of control for this highly invasive species. This study involved examined the Cd2+ sorption dynamics of an alginate encapsulated water hyacinth biochar (BAC) generated at different temperatures and modified using ferric/ferrous sulfate (MBAC). The maximum Cd2+ sorption occurred at a pH of 6 and at a solution temperature of 37 °C. Sorption equilibria for the biochar-alginate capsule (BAC) and modified biochar-alginate capsule (MBAC) treatments fit both the Langmuir (R2 = 0.876 to 0.99) and Freundlich (R2 = 0.849 to 0.971) equations. Langmuir isotherms had a better fit than the Freundlich isotherms, with maximum sorption capacities ranging from 24.2 to 45.8 mg Cd2+ g−1. Larger KL values in Freundlich modeling suggest strong bonding of the BAC and MBAC sorbents to Cd2+, with values of KL in the MBAC treatments ranging between 31 and 178% greater than the BAC treatments. Cd2+ sorption followed pseudo first-order kinetics (R2 = 0.926 to 0.991) with greater efficiency of removal using treatments with biochar generated at temperatures >500 °C. Results from this study highlight the potential for biochar-alginate capsules derived from water hyacinth to be effective for the removal of Cd2+ from wastewaters.

¿Pueden los rasgos hidráulicos ayudar a explicar los límites de distribución actual en dos especies de Nothofagus en los Andes de Chile?

The Andes of central Chile is a geographical gradient with a marked variation in its climatic conditions. Along its slopes, are distributed the evergreen Nothofagus dombeyi and deciduous Nothofagus pumilio species that show differences in their leaf habits, range extensions, and in their limits of latitudinal distribution. Plant ecology proposes that unfavorable climatic conditions are limiting factors that determine the tree species distributions and that the functional hydraulic traits responses allow understanding the mechanisms underlying the current distribution of them. We hypothesize that both species will have lower mean values of KL and KS in populations near to distribution limits compared with middle populations due that unfavorable climatic conditions are predominant in the latitudinal range limits. We quantify in situ the leaf (KL) and xylem (KS) specific hydraulic conductivities in populations of N. dombeyi and N. pumilio near their northern and southern limits of distribution as well as in a middle population along Chilean Andes. Results showed that both species had lower mean values in populations near northern and southern limits compared to populations distributed in middle sites. Also, we found that the hydraulic performance population of N. pumilio distributed in the middle site had higher than N. dombeyi. We concluded that lower hydraulic conductivity associated with distribution limits for both study species implies a lower probability of being affected by embolism, independently of their leaf habits, showing a functional hydraulic convergence to low water availability or cold.

Insight into mass transfer during ultrasound-enhanced adsorption/desorption of blueberry anthocyanins on macroporous resins by numerical simulation considering ultrasonic influence on resin properties

The mass transfer mechanism about ultrasonic enhancement of blueberry anthocyanin adsorption and desorption on macroporous resins were investigated. Ultrasound treatment led to the decrease of resin size, whereas average pore diameter, specific surface area, total pore volume were less affected. Then, the pore volume and surface diffusion model considering ultrasound-induced changes of particle size and surface area was employed to model anthocyanin adsorption process numerically. Generally, sonication enhanced external mass transfer coefficient (kL) and surface diffusion coefficient (Ds) during adsorption. The values of kL and Ds under sonication at 279 W/L and 20 °C were 7.578 × 10−2 cm/s and 2.000 × 10−9 cm2/s, which were 2.0% and 140.1% higher than the kL and Ds values under orbital agitation at 20 °C. Accordingly, anthocyanins penetrated into the interior of macroporous resins faster under sonication. The overall intraparticle diffusion for anthocyanin adsorption was dominated by pore volume diffusion with the contribution percentage higher than 50%. Sonication enhanced the contribution of surface diffusion to the overall diffusion, which was consistent with the increase of Ds with ultrasound energy. Moreover, a general diffusion model also incorporating the variations of particle size and surface area was utilized to model anthocyanin desorption process. The overall anthocyanin diffusivity increased with both ultrasound energy level and temperature. Anthocyanins distributed more homogenously inside resins under sonication at 279 W/L than under other treatments. This work could be a reference for the valorization of anthocyanins in food industry, especially juice and wine industries.

Local head loss caused in connections used in micro-irrigation systems

ABSTRACT Information about local head loss caused by connections employed in micro-irrigation systems is hard to be found in literature. The objective of this research was to experimentally determine the local head losses in connections commonly used in micro-irrigation and propose mathematical models using the theorem of Buckingham. The methodology of tests was based on international standards. The tests were carried out under controlled inlet pressure, at 150 kPa, and five to ten units of each connection model were tested. The curves relating flow and head losses were drawn based on 15 flow conditions, obtained under increase and decrease of flow rate. For each condition, 30 points were collected resulting in a sample size of 900 points in each test. For each connection model evaluated, the following information was obtained: curves of local head loss as a function of flow rate and of local head loss coefficient (KL). The obtained values of KL ranged from 2.72 to 24.16, which become constant for Reynolds number higher than 10,000. The sensitivity of the coefficient related to a ratio of the internal sections in the connections was also verified. The flow exponents presented values close to the one applied by the Darcy-Weisbach equation (m = 2). The models developed for the connections presented a satisfactory performance.

Measurement and Prediction of the Thermal and Electrical Conductivity of Al-Zr Overhead Line Conductors at Elevated Temperatures

In the present work, the thermal conductivity and electrical resistivity of the Al-0.25 Zr (wt.%) alloy have been investigated from 300 K to 600 K. The variations of thermal conductivity (Ktotal) with temperature were measured by using a radial heat flow furnace. The electrical resistivity (ρ) measurements of the alloy depending on the temperature were performed using the standard four-point probe method. The electrical conductivity (σ) was obtained by using the measured electrical resistivity. The thermal conductivity and the electrical resistivity coefficients were determined from the graphs of thermal and electrical resistivity versus temperature for the alloy. The electronic thermal conductivity (Ke) values were obtained from the Wiedemann-Franz and Smith-Palmer equations, and the values of KL were obtained by subtracting Ke fromthe measured values (Ktotal). Ktotal is dominated by Ke, and Ke varies between 208-198 W/mK. The KL decreases from 7.99 to 1.77 W/m K, and σ varies between 1.41x107-2.80x107 Ω-1m-1 in the range of temperature 373-600 K. The enthalpy of fusion (ΔH) and the specific heat capacity (Cp) during the transformation were determined. Thermal diffusivity (α) changes were calculated as a function of temperature from these obtained thermal data.

Non-Newtonian Behavior Effect on Gas-liquid Mass Transfer using an Anchor Impeller for CSTR Bioreactors: A CFD Approach

Objectives: kL a mass transfer coefficient was predicted using CFD (computational fluid dynamics) for analyzing non-newtonian effects on gas liquid mass transfer in a 10 L bioreactor stirred with an Anchor Impeller. Methods/Statistical Analysis: The set up bioreactor configurations were defined by typical culturing conditions used for fungi organism. Bubble breakage frequency and coalescence rate were simulated using Luo - Colaloglou and Tavlarides models and PBM approaches, respectively. Simulated results from different shear rates due to non-newtonian behaviour are compared by analyzing its influences in bubble size and power input. Findings: A clear relationship between high levels of shear rates and small bubble sizes is found in this work. The later is also associated with the high values of kL a simulated (270 h-1) and compared to levels found at low shear rates (62 h-1). Application/Improvements: Impressed by these findings new design optimizations for non-newtonian bioprocessing applications would be improved using CFD. Keywords: Anchor, Bubble Coalescence, Non-Newtonian, Sauter Diameter, CFD

Assessment of natural frequency of installed offshore wind turbines using nonlinear finite element model considering soil-monopile interaction

A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines (OWTs) chosen from five different offshore wind farms in Europe. The simulation is using this model to accurately estimate the natural frequency of these slender structures, as a function of the interaction of the foundations with the subsoil. After a brief introduction to the wind power energy as a reliable alternative in comparison to fossil fuel, the paper focuses on concept of natural frequency as a primary indicator in designing the foundations of OWTs. Then the range of natural frequencies is provided for a safe design purpose. Next, an analytical expression of an OWT natural frequency is presented as a function of soil-monopile interaction through monopile head springs characterized by lateral stiffness KL, rotational stiffness KR and cross-coupling stiffness KLR, of which the differences are discussed. The nonlinear pseudo three-dimensional finite element vertical slices model has been used to analyze the lateral behaviors of monopiles supporting the OWTs of different wind farm sites considered. Through the monopiles head movements (displacements and rotations), the values of KL, KR and KLR were obtained and substituted in the analytical expression of natural frequency for comparison. The comparison results between computed and measured natural frequencies showed an excellent agreement for most cases. This confirms the convenience of the finite element model used for the accurate estimation of the monopile head stiffness.

Finite element analysis of local shear buckling in corrugated web beams

A corrugated web beam (CWB) is a variation to the universal hot rolled or welded I section. CWBs usually comprise of wide thick plate flanges and a thin corrugated web. Due to the accordion effect shear is carried primarily by the corrugated web while bending moments are resisted by the flanges. Under shear action three different modes of shear buckling may be realised in the web – local, global or interactive.This paper describes analyses performed to investigate the local shear buckling behaviour of beams with trapezoidal corrugated webs. Finite element models of cantilever beams with different web geometries were prepared and an elastic eigenvalue buckling analysis was performed using the program ABAQUS. The influence of web thickness, panel width and web height on the local shear buckling coefficient kL was investigated. Values of kL were compared against existing equations from theory and other research. The effect of these dimensions on the local shear buckling stress was also considered. In total, 90 models were analysed.Overall, it was found that the value of kL lies between 5.34 and 8.98. This corresponds to panel boundary conditions that are between simply supported and clamped. The analysis results revealed that kL increases with stockier panels (large panel width to height ratio) but decreases with thicker webs. When the panel width was decreased, local shear buckling occurred at larger stress values. Similar results were observed when the web height was decreased and the panel thickness was increased. These results are consistent with plate buckling theory. Finally, based on these findings an equation to approximate the local shear buckling coefficient in corrugated web beams is recommended.