Filtration Materials Modified with 2D Nanocomposites—A New Perspective for Point-of-Use Water Treatment

Point-of-use (POU) water treatment systems and devices play an essential role in limited access to sanitary safe water resources. The filtering materials applied in POU systems must effectively eliminate contaminants, be readily produced and stable, and avoid secondary contamination of the treated water. We report an innovative, 2D Ti₃C₂/Al₂O₃/Ag/Cu nanocomposite-modified filtration material with the application potential for POU water treatment. The material is characterized by improved filtration velocity relative to an unmodified reference material, effective elimination of microorganisms, and self-disinfecting potential, which afforded the collection of 99.6% of bacteria in the filter. The effect was obtained with nanocomposite levels as low as 1%. Surface oxidation of the modified material increased its antimicrobial efficiency. No secondary release of the nanocomposites into the filtrate was observed and confirmed the stability of the material and its suitability for practical application in water treatment.     

Investigation of the Quasi-Static Penetration Resistance Behaviour of Carbon/Aramid Fibre-Reinforced PP Laminate

This work presents the experimental results of a quasi-static attempt at the penetration of hybrid and non-hybrid laminates reinforced with aramid and carbon fibres on a thermoplastic polypropylene matrix. The hybrid laminates were prepared in two fibre combinations: carbon–aramid–carbon (CAC), in which the carbon fibres comprised the outer (lining) layers, and aramid–carbon–aramid (ACA) with carbon fibres in their intermediate layers. A quasistatic penetration attempt was performed for two coefficients: SPR—support span to punch diameter ratio, (SPR = 2 and 5). The SPR = Ds/Dp was calculated as the ratio of the support (Ds) to the punch diameter (Dp). A punch with a rounded 9-mm diameter tip was used to penetrate the material. Percentage changes of penetration energy (%E) and of maximum load (%P) compared to a non-hybrid laminate with carbon fibres were calculated in order to estimate the impact of hybridisation on the properties of laminates. The maximum load recorded during a quasi-static penetration test was used to calculate the PSS (punch shear strength) of the laminates. The damage was observed after the penetration test. It was observed that both the order of layers of laminate reinforcement as well as the SPR coefficient used in the test influenced the obtained results and the laminate damage mechanism.     

Weakly Hydrated Anion Exchangers Doped with Cu2O and Cu0 Particles—Thermogravimetric Studies

Hybrid ion exchangers (HIXs) containing fine Cu₂O and Cu⁰ particles were subjected to thermal analysis in order to determine their hygroscopic water content (with regard to their anomalously low porosity) and to determine the effect of the oxidation state of the copper atom in the deposit on the thermal properties of composite materials. Commercially available anion exchangers, Amberlite IRA 900Cl (macroreticular, M) and Amberlite IRA 402OH (gel-like, G), were used as supporting materials. M/Cu₂O, G/Cu₂O, M/Cu and G/Cu, containing 4.3–8.4 wt% Cu, were subjected to thermal analysis under respectively air and N₂. TG/DTG curves revealed that dry M/Cu and G/Cu contained as little as 7.2% and 4.3% hygroscopic water, while M/Cu₂O and G/Cu₂O contained respectively 10.6% and 9.4% (Cu⁰ was a stronger water repellent than Cu₂O). The oxidation state of the copper atom in the deposit was found to affect the amount of the forming char, and also Cu⁰ was found to contribute to the formation of more char than in the pyrolysis of the pure resin (the anion exchanger with no copper deposit). Under air the two kinds of particles transformed into CuO, while under N₂ metallic copper and char (from the resin phase) made up the solid residue. This means that in the pyrolysis of the HIXs the inorganic phase participated in char formation and it also transformed itself (undergoing reduction when possible). The above findings provide a basis for in-depth research aimed at the innovative use of copper-containing HIXs and at obtaining usable composite materials with a designed (organic-inorganic) composition.     

Effect of Modification of Amorphous Silica with Ammonium Agents on the Physicochemical Properties and Hydrogenation Activity of Ir/SiO2 Catalysts

The modification of commercial silica with solutions of NH₄F or NH₄Cl salts, followed by thermal treatment, enabled generation of the acidic sites in SiO₂ and changed its textural properties. The use of ammonium salts solution also caused the generation of additional porosity. Using NH₄F solution caused significant decrease in the specific surface area and the increase in the average pore diameter. The number and strength of resulting acid sites depend on the nature of anion in the applied ammonium salt and the concentration of salt solution. It has been found that the sample treated with NH₄F presented higher total acidity (TPD–NH₃) and the amount as well as the strength of acid sites increased with the concentration of the used modifier. As modified amorphous SiO₂ materials used as a support for iridium (1 wt %, Ir(acac)₃) nanoparticles permitted to obtain highly active catalysts for toluene hydrogenation under atmospheric pressure. The highest activity (expressed as the apparent rate and TOF) was obtained for iridium catalysts supported on silica modified by NH₄F with the highest acidity. The modification of silica with NH₄F favors the generation of centers able to adsorb toluene, which results in higher activity of this catalyst.     

Selected risk factors of fungal infections in human populations

For the past twenty years, invasive fungal infections have dramatically increased resulting in the high morbidity and mortality. The main reason of these infections is the development of invasive diagnostic and therapeutic technologies. Immunosuppression, neutropenia, broad-spectrum antibacterial agents, corticosteroids, chemotherapy, central intravascular catheter, total parenteral nutrition are the major risk factors of the invasive fungal infections. Most of these factors are very common for hospitalized patients. For example, patients with fungemia are more likely to die during hospitalization then those with bloodstream infection caused by nonfungal pathogens. Unfortunately, diagnosis and diagnostic methods of fungal infection are still difficult.     

Influence of insertion-deletion polymorphism of the angiotensin converting enzyme gene on left ventricular hypertrophy in patients with aortic stenosis--differences in men and women

The role of different parameters (including genetic factors) on the timing and extend of left ventricle hypertrophy in patients with aortic stenosis is not defined. In our study we analyze the influence of clinical, echocardiographic parameters and I/D polymorphism of the angiotensin converting enzyme gene on the left ventricle hypertrophy (left ventricle mass index) in this group of patients. The study was done with the group of 302 pts with aortic stenosis--120 women and 182 men; mean age 58 +/- 11 yrs. Stepwise (backward) regression was used to assess the influence of the analyzed parameters (age, gender, history of hypertension, EF, MGA, presence of significant coronary artery disease and I/D ACE polymorphism) on the LVH in the all pts and in the women and the men separately. In the whole group the LVMI depends on EF (t = -6.5; p = 0.0001--higher LVMI in lower EF), MGA (t = 3.9; p = 0.0001--higher LVMI in higher MGA) and gender (t = 2.8; p = 0.005--higher LVMI in men). In women LVMI was related with EF (t = -3.6; p = 0.001--higher LVMI in lower EF), age (t = 2.9; p = 0.004--higher LVMI in older pts) and MGA (t = 2.5; p = 0.013--higher LVMI in higher MGA). In men the LVMI depends on EF (t = -4.8; p = 0.0001--higher LVMI in lower EF) and MGA (t = 1.98; p = 0.049--higher LVMI in higher MGA). Significant relationship between LVMI and results of I/D ACE polymorphism was observed both in women and men. I/D polymorphism relationship with LVMI was divergent in these 2 groups--association of higher LVMI with lack of DD type of polymorphism in women and presence of DD polymorphism in men. CONCLUSIONS: 1. Left ventricle hypertrophy in pts aortic stenosis is higher in men than in women. 2. In women left ventricle hypertrophy is related with ejection fraction, maximal aortic gradient, age and I/D ACE polymorphism; in men it is related to EF, MGA and I/D ACE polymorphism. 3. The influence of I/D ACE polymorphism on the left ventricle hypertrophy is divergent in women and men--in women related to the lack of DD polymorphism, in men related to the presence of DD polymorphism.