Coniferous Wood Sawdust-based Activated Carbons as Adsorbents Obtained with the Use of Microwave Radiation

Activated carbons were prepared by physical and direct activation of sawdust pellets coming from coniferous trees, with the use of microwave radiation. The activated carbons obtained were used as adsorbents for the removal of methylene blue (MB) from aqueous solutions. Liquid-phase adsorption experiments were conducted and the maximum adsorption capacity of each activated carbon sample was determined. The effects of activation procedure as well as adsorption tests parameters i.e., temperature, pH, initial methylene blue concentration, and contact time on the sorption capacity of each activated carbon were investigated. The kinetic models for MB adsorption on the activated carbons were also studied. Better fit to the experimental data was obtained with the Langmuir isotherm than Freundlich one, for all samples.     

Sorption of Cd(II)-MGDA Complexes on Polyacrylate Anion Exchangers

The possibility of polyacrylic anion exchangers application in the removal of Cd(II) complexes with MGDA (methylglycinediacetic acid) from aqueous solutions was presented. Batch sorption experiments were performed using Amberlite IRA 458 and Amberlite IRA 958. The initial solution pH, the initial concentration of sorbed complexes in the molar ratio M(II)-MGDA = 1:1, the temperature, as well as the contact time were varied. The kinetics of Cd(II) sorption in the presence of MGDA was analyzed. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were also applied to describe the adsorption isotherm. The values of the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicated that in the majority of cases the sorption process was spontaneous and endothermic. From the determined breakthrough curves, the distribution coefficients and the ion exchange capacities were calculated.     

Comparison of the effects of different chemical activation methods on properties of carbonaceous adsorbents obtained from cherry stones

A method for obtaining activated carbons from cherry stones by chemical activation with NaOH is described. Carbonaceous adsorbents were obtained by two methods of activation (physical mixing and impregnation) and two variants of thermal treatment (at a constant or increasing temperature). Cherry stones were proved to be effective cheap precursors of carbon adsorbents, characterised by large pore volume (ranging from 0.22 to 0.47 cm³/g) and good sorption abilities (iodine number from 343 to 996 mg/g). The activated carbons obtained usually have strongly microporous structure and acidic surface character. The best physicochemical properties and adsorption properties towards iodine were found to be shown by the carbon samples obtained by physical mixing of the precursor or char with the activating agent followed by activation at 600 °C.     

The effect of linear velocity and flux on performance of ceramic graded permeability membranes when processing skim milk at 50°C

Raw milk (about 500 kg) was cold (4°C) separated and then the skim milk was pasteurized at 72°C and a holding time of 16 s. The milk was cooled to 4°C and stored at ≤4°C until processing. The skim milk was microfiltered using a pilot-scale ceramic graded permeability (GP) microfilter system equipped with 0.1-µm nominal pore diameter ceramic Membralox membranes. First, about 155 kg of pasteurized skim milk was flushed through the system to push the water out of the system. Then, additional pasteurized skim milk (about 320 kg) was microfiltered (stage 1) in a continuous feed-and-bleed 3× process using the same membranes. The retentate from stage 1 was diluted with pasteurized reverse osmosis water in a 1:2 ratio and microfiltered (stage 2) with a GP system. This was repeated 3 times, with total of 3 stages in the process (stage 1 = microfiltration; stages 2 and 3 = diafiltration). The results from first 3 stages of the experiment were compared with previous data when processing skim milk at 50°C using ceramic uniform transmembrane pressure (UTP) membranes. Microfiltration of skim milk using ceramic UTP and GP membranes resulted in similar final retentate in terms of serum proteins (SP) removed. The SP removal rate (expressed by kilogram of SP removed per meter-squared of membrane area) was higher for GP membranes for each stage compared with UTP membranes. A higher passage of SP and SP removal rate for GP than UTP membranes was achieved by using a higher cross-flow velocity when processing skim milk. Increasing flux in subsequent stages did not affect membrane permeability and fouling. We operated under conditions that produced partial membrane fouling, due to using a flux that was less than limiting flux but higher than critical flux. Because the critical flux is a function of the cross-flow velocity, the difference in critical flux between UTP and GP membranes resulted only from operating under different cross-flow velocities (6.6 vs 7.12 for UTP and GP membranes, respectively). Conditions that allow microfiltration operation at higher flux will reduce the membrane surface area required to process the same amount of milk in the same length of time. Less membrane surface area reduces investment costs and uses less energy, water, and chemicals to clean the microfiltration system.     

Mechanical characteristics of artificial cell walls

Artificial plant cell walls were produced from bacterial cellulose and cell wall constituents. The artificial cell walls were stored at low, medium and high relative humidity, and then subjected to micro-mechanical tests. From chemical composition and microstructure analysis it was found that, among all artificial cell wall materials produced, the most representative analogue of natural apple cell wall was based on bacterial cellulose supplemented with xyloglucan and pectin. Uniaxial tensile tests revealed that the different cell wall materials differed in their mechanical properties; increasing the humidity during storage resulted in a decrease in the value of the secant modulus. The cell wall model material obtained may be used for the simulation of the effect of external factors on the physical and chemical properties of cell walls.     

New contact acoustic emission detector for texture evaluation of apples

A new contact acoustic emission detector (CAED) was developed for the instrumental texture evaluation of apples. The goal of this work was to determine the relations between instrumental parameters and sensory texture attributes, and to develop calibration models for prediction of the sensory texture of apples with CAED. Seven apple cultivars were used for the construction and validation of the models. CAED is particularly useful for evaluation of sensory crispness, crunchiness and hardness. There is also a significant correlation of acoustic emission counts with juiciness, mealiness and overall texture. Validation of the models indicates better prediction of these sensory attributes by total acoustic emission counts than prediction by puncture firmness in terms of variance explained, root-mean-square of a model prediction, and bias.     

Flux and transmission of β-casein during cold microfiltration of skim milk subjected to different heat treatments

Raw skim milk was subjected to different heat treatments: thermization (65°C, 20 s), pasteurization (72°C, 15 s), and no heat treatment (milk was microfiltered using 1.4-µm membranes at 50°C for bacteria removal; 1.4 MF). The milk (thermized, pasteurized, and 1.4 MF) was cooled and stored at 2°C until processing (at least 24 h) with cold (～6°C) microfiltration using a benchtop crossflow pilot unit (Pall Membralox XLAB 5, Pall Corp., Port Washington, NY) equipped with 0.1-µm nominal pore diameter ceramic Membralox membrane (ET1-070, α-alumina, Pall Corp.). The flux was monitored during the process, and β-casein transmission and removal were calculated. The study aimed to indicate the conditions that should be applied to maximize β-casein passage through the membrane during cold microfiltration (5.6 ± 0.4°C) of skim milk. The proper selection of heat treatment parameters (temperature, time) of the feed before the cold microfiltration process will increase β-casein removal. It is not clear whether the difference in β-casein transmission between 1.4 MF, thermized, and pasteurized milk results from the effect of heat treatment conditions on β-casein dissociation from the casein micelles or on passage of β-casein through the membrane. The values of the major parameters (permeation flux and tangential flow velocity, through the wall shear stress) responsible for a proper membrane separation process were considerably lower than the critical values. It seems that the viscosity of the retentate has a great effect on the performance of the microfiltration membranes for protein separation at refrigerated temperatures.     

Postural instability-induced compensative movements in virtual reality

Virtual Reality - During virtual reality usage, two egocentric mental representations are constructed simultaneously. The first representation is rooted in the physical reality in which VR is set...     

Pharmacotherapy considerations in pregnant patients on hemodialysis

Purpose

Successful pregnancy rates on dialysis are increasing with the advent of intensive hemodialysis and advances in medical management.

Summary

Data support the use of intensive hemodialysis in pregnant women with end-stage kidney disease (ESKD). This paper provides an overview of common pharmacotherapeutic changes in management when caring for a pregnant woman receiving intensive hemodialysis. Pregnant patients on peritoneal dialysis were excluded from this analysis due to insufficient data. Topics covered include those related to anemia (iron and erythropoietin stimulating agents), blood pressure agents, monitoring of phosphorus, as well as nutrition and anticoagulation.

Conclusion

When patients on hemodialysis become pregnant, medication adjustments are needed regarding antihypertensives, anemia management, and mineral-bone disease management as many agents require dose adjustment, switching agents due to teratogenicity, or cessation due to fetal complications. There are minimal data in this population; however, successful and healthy infants have been delivered in this patient population with the medication changes discussed.     

Van der Waals Heteroepitaxy of GaSe and InSe,Quantum Wells,and Superlattices

Bandgap engineering and quantum confinement in semiconductor heterostructures provide the means to fine-tune material response to electromagnetic fields and light in a wide range of the spectrum. Nonetheless, forming semiconductor heterostructures on lattice-mismatched substrates is a challenge for several decades, leading to restrictions for device integration and the lack of efficient devices in important wavelength bands. Here, it is shown that the van der Waals epitaxy of 2D GaSe and InSe heterostructures occur on substrates with substantially different lattice parameters, namely silicon and sapphire. The GaSe/InSe heteroepitaxy is applied in the growth of quantum wells and superlattices presenting photoluminescence and absorption related to interband transitions.