Microwave and conventional treatment of low-cement high-alumina castables with different water to cement ratios; Part I. Drying

The aim of this study was to determine the effect of the microwave and conventional drying method on the strength, porosity and composition of low-cement alumina castables with various water to cement ratios (wcr). High-alumina low-cement castable samples were prepared with different w/c ratios: 0.64, 0.75, 0.82 and 1.13. Changes in wcr were effected through volumetric replacement of cement with 0–0,045-mm tabular alumina having a comparable particle size. Water content in all the composition was constant (4,5%). After curing, the samples were dried conventionally in a laboratory electric drier or in a laboratory microwave drier. After drying open porosity and modulus of rupture were determined. The pore size distribution, pore median and tortuosity of the samples were measured by the mercury porosimetry method. Phase composition was determined using X-ray diffraction. The Rietveld method was used for quantitative analysis. It was found that at low wcr (0.62) the main hydrate formed in the castable was C₃AH₆, which caused a release of a smaller amount of water during the drying process, mainly pore water, resulting in lower open porosity and lower pore size than in the castables with a high wcr (1.13). At a low wcr, the strenght of castable was higher due to a higher amount of hydrates, low porosity and small pore size. On the other hand, at a high wcr, the strength of castable was lower owing to a higher amount of water released in the drying process, which led to loosening the structure of castable. With an increased water-to-cement ratio the degree of CA₂ hydration decreased. The temperature rise due to cement hydration probably influenced the kinetics of this process.     

Selective Synthesis of Polyoxyethylene–Polyoxypropylene Block Copolymer (Poloxamer) Fatty Acid Monoesters Over Homogeneous Organotin Catalyst

The synthesis of selected polyoxyethylene–polyoxypropylene block copolymer (poloxamer) fatty acid monoesters is presented. Organotin homogeneous catalyst Sn bis(2‐ethylhexanoate) effectively catalyzed the esterification reaction of (EO)–(PO)–(EO) block copolymer (poloxamer) with fatty acids. The reaction proceeded in high yield and high selectivity to monoesters. Content of diesters in final products was below 1 wt%. The new protocol opened up a high yield and high selective method for the synthesis of poloxamer fatty acid monoesters. These products are potentially interesting for industrial applications, e.g. in lubricants, cosmetics and, in particular, as potential emulsifying agents compatible with hydrocarbon bases, such as paraffin.     

Silicon-Boron Alloys as New Ultra-High Temperature Phase-Change Materials: Solid/Liquid State Interaction with the h-BN Composite

Silicon-boron alloys have been recently pointed out as novel ultra-high temperature phase change materials for applications in Latent Heat Thermal Energy S     

Milling as a method of surface pre-treatment of steel for adhesive bonding

The paper analyses the impact of mechanical milling pre-treatment parameters on adhesive joint strength. Comparison of surface roughness of adherends after milling and its effect on adhesive joint strength is analysed in strength tests. The tests were performed on C45 structural steel specimens, which were subjected to machining at different parameters, with two types of milling cutters. Adherends were degreased prior to adhesive joining. Two types of end mills used in tests were NFPaφ20 high-speed steel cutter and R390-020B20-11L indexable milling cutter. The machining was carried out at three cutting speeds: 0.05, 0.15 and 0.30 mm/tooth. Adherends were joined with an adhesive composition of Epidian 57 epoxy resin and Z-1 curing agent.     

Manganese-Labeled Alginate Hydrogels for Image-Guided Cell Transplantation

Cell transplantation has been studied extensively as a therapeutic strategy for neurological disorders. However, to date, its effectiveness remains unsatisfactory due to low precision and efficacy of cell delivery; poor survival of transplanted cells; and inadequate monitoring of their fate in vivo. Fortunately, different bio-scaffolds have been proposed as cell carriers to improve the accuracy of cell delivery, survival, differentiation, and controlled release of embedded stem cells. The goal of our study was to establish hydrogel scaffolds suitable for stem cell delivery that also allow non-invasive magnetic resonance imaging (MRI). We focused on alginate-based hydrogels due to their natural origin, biocompatibility, resemblance to the extracellular matrix, and easy manipulation of gelation processes. We optimized the properties of alginate-based hydrogels, turning them into suitable carriers for transplanted cells. Human adipose-derived stem cells embedded in these hydrogels survived for at least 14 days in vitro. Alginate-based hydrogels were also modified successfully to allow their injectability via a needle. Finally, supplementing alginate hydrogels with Mn ions or Mn nanoparticles allowed for their visualization in vivo using manganese-enhanced MRI. We demonstrated that modified alginate-based hydrogels can support therapeutic cells as MRI-detectable matrices.     

Straight to the Point—The Novel Strategies to Cure Pediatric AML

Although the outcome has improved over the past decades, due to improved supportive care, a better understanding of risk factors, and intensified chemotherapy, pediatric acute myeloid leukemia remains a life-threatening disease, and overall survival (OS) remains near 70%. According to French-American-British (FAB) classification, AML is divided into eight subtypes (M0–M7), and each is characterized by a different pathogenesis and response to treatment. However, the curability of AML is due to the intensification of standard chemotherapy, more precise risk classification, improvements in supportive care, and the use of minimal residual disease to monitor response to therapy. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. Therefore, it is essential to identify new, more precise molecules that are targeted to the specific abnormalities of each leukemia subtype. Here, we review abnormalities that are potential therapeutic targets for the treatment of AML in the pediatric population.     

Determination of polyphenolic compounds in commercial herbal drugs and spices from Lamiaceae: thyme,wild thyme and sweet marjoram by chromatographic techniques

HPLC and HPTLC methods were used for a qualitative and quantitative determination of luteolin-7-O-β-glucuronide, lithospermic acid, rosmarinic acid and mthyl rosmarinate, together with other known compounds, in commercial herbal drugs and spices from lamiaceous species: Thymi herba, Serpylli herba and Majoranae herba. The contents of analyzed compounds in the studied hydrophilic extracts, prepared form herbal sources, were established using a C18 column with acetonitrile–water–formic acid as a mobile phase. The HPLC method was validated for linearity, precision and accuracy. Luteolin-7-O-β-glucuronide and lithospermic acid were identified as new wild thyme constituents, luteolin-7-O-β-glucuronide and methyl rosmarinate as new compounds in sweet marjoram. Methyl rosmarinate was isolated for the first time from thyme. The investigated herbal drugs and spices provide polyphenols in high amounts, even up to 84.3 mg per 1 g of a dried herb.     

Concentration of contaminated single-phase detergents by means of unit and integrated membrane processes

Unit and integrated pressure-driven membrane processes were investigated in a semi-pilot scale for the purification and concentration of contaminated cleaning solutions. For the tests, liquid acidic and alkaline single-phase detergents tailor-made for CIP systems in the dairy industry were selected. The effect of the permeate recovery rate on the quality of recovered solutions was evaluated.

Integrated purification processes provided a very high separation of the milk components with a slight weakening of the detergency properties of the permeate. The least effective integrated treatment option (PM5+AFC30) enabled 100% retention of proteins, and over 98% retention of low molecular weight lactose.