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.     

Spherical Silica Modified with Magnesium and Ruthenium—Synthesis,Characterization and Catalytic Properties

The design of different bimetallic catalysts is an important area of catalytic research in the context of their possible applications in the cascade processes, meeting the requirements of the so-called green chemistry. In this study, such catalysts were obtained by the incorporation of magnesium species into spherical silica, which was in the next step covered with porous silica and modified with ruthenium species. The structure and chemical composition of the materials obtained were determined by XRD measurements, low temperature N₂ adsorption/desorption, SEM, ICP-OES and XPS methods. The catalytic activities of materials obtained were tested in 2-propanol decomposition and hydrogenation of levulinic acid. The results obtained confirmed the successful coverage of nanospheres with porous silica. A much higher concentration of ruthenium species was found on the surface of the catalysts than in their bulk. The opposite relationship was observed for magnesium species. The modification of nanospheres with silica had a positive effect on the catalytic activity of the materials obtained. For the most active sample, i.e., Ru/NS/3Mg/NS, 49% of levulinic acid conversion in its hydrogenation process was reported with γ-valerolactone as the only product.     

Amorphous RuCoP Ultrafine Nanoparticles Supported on Carbon as Efficient Catalysts for Hydrogenation of Adipic Acid to 1,6-Hexanediol

As an important raw material for organic synthesis, the 1,6-hexanediol (HDOL) is synthesized by the complicated two-step process traditionally. The hydrogenation of adipic acid (AA) is a potential way to prepare 1,6-hexanediol. At present, amorphous RuMP (M: Co, Ni, Fe, etc.)-based alloys with low Ru content were developed by co-precipitation as the efficient catalysts for converting AA to HDOL via hydrogenation. Among these RuMP catalysts, RuCoP alloys exhibited the highest selectivity and yield to HDOL owing to the electronic effect. The selectivity and yield of HDOL for the optimized RuCoP/C sample was achieved to 80% and 64%, respectively, at 65 bar and 220 °C. A series of RuCoP alloys with different degrees of crystallinity and particle sizes were prepared to investigate the effect of morphology and structure on its catalytic performance. The results indicated that the high catalytic activity of RuCoP/C resulted from its rich active sites due to its amorphous phase and small particle size.     

The Photoluminescent Properties of New Cationic Iridium(III) Complexes Using Different Anions and Their Applications in White Light-Emitting Diodes

Three cationic iridium(III) complexes [Ir(ppy)₂(phen)][PF₆] (C1), [Ir(ppy)₂(phen)]₂SiF₆ (C2) and [Ir(ppy)₂(phen)]₂TiF₆ (C3) (ppy: 2-phenylpyridine, phen: 1, 10-phenanthroline) using different anions were synthesized and characterized by ¹H Nuclear magnetic resonance (¹HNMR), mass spectra (MS), Fourier transform infrared (FTIR) spectra and element analysis (EA). After the ultraviolet visible (UV-vis) absorption spectra, photoluminescent (PL) properties and thermal properties of the complexes were investigated, complex C1 and C3 with good optical properties and high thermal stability were used in white light-emitting diodes (WLEDs) as luminescence conversion materials by incorporation with 460 nm-emitting blue GaN chips. The integrative performances of the WLEDs fabricated with complex C1 and C3 are better than those fabricated with the widely used yellow phosphor Y₃Al₅O₁₂:Ce³⁺ (YAG). The color rendering indexes of the WLEDs with C1 and C3 are 82.0 and 82.6, the color temperatures of them are 5912 K and 3717 K, and the maximum power efficiencies of them are 10.61 Lm·W⁻¹ and 11.41 Lm·W⁻¹, respectively.     

The Zn1−xPbxCr2Se4—Single Crystals Obtained by Chemical Vapour Transport—Structure and Magnetic,Electrical, and Thermal Properties

Monocrystalline chalcogenide spinels ZnCr₂Se₄ are antiferromagnetic and semiconductor materials. They can be used to dope or alloy with related semiconducting spinels. Therefore, their Pb-doped display is expected to have unique properties and new potential applications. This paper presents the results of dc and ac magnetic measurements, including the critical fields visible on the magnetisation isotherms, electrical conductivity, and specific heat of the ZnCr₂S₄:Pb single crystals. These studies showed that substituting the diamagnetic Pb ion with a large ion radius for the Zn one leads to strong short-range ferromagnetic interactions in the entire temperature range and spin fluctuations in the paramagnetic region at H_dc = 50 kOe.     

Lassa Fever Virus Binds Matriglycan—A Polymer of Alternating Xylose and Glucuronate—On α-Dystroglycan

Lassa fever virus (LASV) can cause life-threatening hemorrhagic fevers for which there are currently no vaccines or targeted treatments. The late Prof. Stefan Kunz, along with others, showed that the high-affinity host receptor for LASV, and other Old World and clade-C New World mammarenaviruses, is matriglycan—a linear repeating disaccharide of alternating xylose and glucuronic acid that is polymerized uniquely on α-dystroglycan by like-acetylglucosaminyltransferase-1 (LARGE1). Although α-dystroglycan is ubiquitously expressed, LASV preferentially infects vascular endothelia and professional phagocytic cells, which suggests that viral entry requires additional cell-specific factors. In this review, we highlight the work of Stefan Kunz detailing the molecular mechanism of LASV binding and discuss the requirements of receptors, such as tyrosine kinases, for internalization through apoptotic mimicry.     

A Pathway toward a New Era of Open-Cell Polyurethane Foams—Influence of Bio-Polyols Derived from Used Cooking Oil on Foams Properties

In order to create greener polyurethane (PUR) foams, modified used cooking oils (UCO) were applied as starting resources for the synthesis of bio-polyols. The bio-polyols were produced using transesterification of UCO with diethylene glycol (UCO_DEG) and triethanolamine (UCO_TEA). Next, open-cell PUR foams were synthesized by replacing 20, 40, 60, 80 and 100% of the petrochemical polyol with the bio-polyol UCO_DEG or UCO_TEA. It was observed that an increasing bio-polyol content (up to 60%) led to an increase of the closed cell content. However, a further increase in the bio-polyol content up to 100% resulted in foam cell opening. The bio-foams obtained in the experiment had an apparent density of 13–18 kg/m³. The coefficient of thermal conductivity was determined at three different average temperatures: 10, 0 and −10 °C. The PUR bio-foams modified with bio-polyol UCO_TEA had lower values of thermal conductivity, regardless of the average temperature (35.99–39.57 mW/m·K) than the foams modified with bio-polyol UCO_DEG (36.95–43.78 mW/m·K). The compressive strength of most of the bio-foams was characterized by a higher value than the compressive strength of the reference material (without bio-polyol). Finally, it was observed that the bio-materials exhibited dimensional stability at 70 °C.     

Temperature-Dependent Growth and Evolution of Silicene on Au Ultrathin Films—LEEM and LEED Studies

The formation and evolution of silicene on ultrathin Au films have been investigated with low energy electron microscopy and diffraction. Careful control of the annealing rate and temperature of Au films epitaxially grown on the Si(111) surface allows for the preparation of a large scale, of the order of cm², silicene sheets. Depending on the final temperature, three stages of silicene evolution can be distinguished: (i) the growth of the low buckled phase, (ii) the formation of a layered heterostructure of the low buckled and planar phases of silicene and (iii) the gradual destruction of the silicene. Each stage is characterized by its unique surface morphology and characteristic diffraction patterns. The present study gives an overview of structures formed on the surface of ultrathin Au films and morphology changes between room temperature and the temperature at which the formation of Au droplets on the Si(111) surface occurs.     

The Studies on α-Pinene Oxidation over the TS-1. The Influence of the Temperature,Reaction Time,Titanium and Catalyst Content

The work presents the results of studies on α-pinene oxidation over the TS-1 catalysts with different Ti content (in wt%): TS-1_1 (9.92), TS-1_2 (5.42), TS-1_3 (3.39) and TS-1_4 (3.08). No solvent was used in the oxidation studies, and molecular oxygen was used as the oxidizing agent. The effect of titanium content in the TS-1 catalyst, temperature, reaction time and amount of the catalyst in the reaction mixture on the conversion of α-pinene and the selectivities of appropriate products was investigated. It was found that it is most advantageous to carry out the process of α-pinene oxidation in the presence of the TS-1 catalyst with the titanium content of 5.42 wt% (TS-1_2), at the temperature of 85 °C, for 6 h and with the catalyst TS-1 content in the reaction mixture of 1 wt%. Under these conditions the conversion of α-pinene amounted to 34 mol%, and the selectivities of main products of α-pinene oxidation process were: α-pinene oxide (29 mol%), verbenol (15 mol%) and verbenone (12 mol%). In smaller quantities also campholenic aldehyde, trans-pinocarveol, myrtenal, myrtenol, L-carveol, carvone and 1,2-pinanediol were also formed. These products are of great practical importance in food, cosmetics, perfumery and medicine industries. Kinetic studies were also performed for the studied process.     

Preparation of Wax-Based Warm Mixture Additives from Waste Polypropylene (PP) Plastic and Their Effects on the Properties of Modified Asphalt

The production of high-performance, low-cost warm mix additives (WMa) for matrix asphalt remains a challenge. The pyrolysis method was employed to prepare wax-based WMa using waste polypropylene plastic (WPP) as the raw material in this study. Penetration, softening point, ductility, rotational viscosity, and dynamic shear rheological tests were performed to determine the physical and rheological properties of the modified asphalt. The adhesion properties were characterized using the surface free energy (SFE) method. We proved that the pyrolysis temperature and pressure play a synergistic role in the production of wax-based WMa from WPPs. The product prepared at 380 °C and 1.0 MPa (380-1.0) can improve the penetration of matrix asphalt by 61% and reduce the viscosity (135 °C) of matrix asphalt by 48.6%. Furthermore, the modified asphalt shows favorable elasticity, rutting resistance, and adhesion properties; thus, it serves as a promising WMa for asphalt binders.     

Studies on the Impact of the Photoinitiator Amount Used during the PVP-Based Hydrogels’ Synthesis on Their Physicochemical Properties

In recent times, a great interest is directed to developing biomaterials incorporated with various therapeutical substances which may enhance them with new properties and thus increase their application potential. In this work, polyvinylpyrrolidone (PVP)-based hydrogels modified with Aloe vera juice and vitamin C and differing in the amount of the photoinitiator used during their synthesis were developed. Analysis of hydrogels included characterization of their chemical structure via FT-IR spectroscopy, sorption properties, wettability, surface morphology, behavior in simulated physiological liquids and mechanical properties. Finally, hydrogels’ cytotoxicity towards L929 murine fibroblasts using MTT reduction assay was additionally verified. It was demonstrated that as the amount of the photoinitiator used during the synthesis of hydrogels increased, the smoother their surface and the higher their hydrophilicity. Next, the greater the amount of the photoinitiator, the lower is the percentage elongation of the hydrogel and the greater the hardness. In turn, the swelling ability of hydrogels depended strongly on the type of the absorbed liquid—swelling ratios of samples in distilled water were 24% higher than in SBF, 18% higher than in Ringer liquid, and 32% higher than in hemoglobin wherein the amount of the photoinitiator did not affect this property. Additionally, hydrogels were stable and did not degrade in simulated physiological liquids. The only changes in pH of the incubation media were probably caused by the active substances release from hydrogels which was also confirmed via a lesser intensity of the absorption band on FT-IR spectra corresponding to the functional group occurring in compounds included in Aloe vera juice. Importantly, the viability of fibroblasts incubated with developed materials was at least 86%. Thus the hydrogels, due to their properties, seem to show application potential to be used for biomedical purposes, e.g., as innovative dressing materials.     

Effects of Shot Peening and Cavitation Peening on Properties of Surface Layer of Metallic Materials—A Short Review

Shot peening is a dynamically developing surface treatment used to improve the surface properties modified by tool, impact, microblasting, or shot action. This paper reviews the basic information regarding shot peening methods. The peening processes and effects of the shot peening and cavitation peening treatments on the surface layer properties of metallic components are analysed. Moreover, the effects of peening on the operational performance of metallic materials are summarized. Shot peening is generally applied to reduce the surface roughness, increase the hardness, and densify the surface layer microstructure, which leads to work hardening effects. In addition, the residual compressive stresses introduced into the material have a beneficial effect on the performance of the surface layer. Therefore, peening can be beneficial for metallic structures prone to fatigue, corrosion, and wear. Recently, cavitation peening has been increasingly developed. This review paper suggests that most research on cavitation peening omits the treatment of additively manufactured metallic materials. Furthermore, no published studies combine shot peening and cavitation peening in one hybrid process, which could synthesize the benefits of both peening processes. Moreover, there is a need to investigate the effects of peening, especially cavitation peening and hybrid peening, on the anti-wear and corrosion performance of additively manufactured metallic materials. Therefore, the literature gap leading to the scope of future work is also included.     

Electronic and Optical Properties of Rocksalt Mg1−xZnxO and Wurtzite Zn1−xMgxO with Varied Concentrations of Magnesium and Zinc

The structural, electronic and optical properties of rocksalt Mg1−xZnxO and wurtzite Zn1−xMgxO with the concentration of Zn and Mg varying from 0.125 to 0.875 were investigated using density functional theory (DFT), DFT+U, linear response theory and the Bethe–Salpeter equation. According to the experimental band gap for varied concentrations of magnesium and zinc, modeling the supercell was utilized for the varied concentrations of Mg/Zn/O compounds in order to not only avoid constructing the complicated interface systems that are observed in the experiments but also take into account the excitonic effects that usually require huge computational resources. From the calculated density of states, the Zn states are highly related to the edge of the conduction band minimum and responsible for the width of bandgap. In addition, the contribution of Zn–d states is below expectations as they are located away from the VBM. As for the optical response, an increase in Zn concentration would cause a red-shifted spectrum, on the whole. In contrast, the higher concentration of Mg also triggers the blue-shift of the optical spectrum. In addition, anisotropic properties could be found in the spectrum with consideration of the excitonic effects, whereas there is no apparent difference in optical response based on linear response theory. In addition, the optical features of this work reflect the characteristic peaks of the literature around the absorption onset.     

α-Amidoamids as New Replacements of Antibiotics—Research on the Chosen K12, R2–R4 E. coli Strains

A preliminary study of α-amidoamids as new potential antimicrobial drugs was performed. Special emphasis was placed on selection of structure of α-amidoamids with the highest biological activity against different types of Gram-stained bacteria by lipopolysaccharide (LPS). Herein, Escherichia coli model strains K12 (without LPS in its structure) and R1–R4 (with different length LPS in its structure) were used. The presented work showed that the antibacterial activity of α-amidoamids depends on their structure and affects the LPS of bacteria. Moreover, the influence of various newly synthesized α-amidoamids on bacteria possessing smooth and rought LPS and oxidative damage of plasmid DNA caused by all newly obtained compounds was indicated. The presented studies clearly explain that α-amidoamids can be used as substitutes for antibiotics. The chemical and biological activity of the analysed α-amidoamids was associated with short alkyl chain and different isocyanides molecules in their structure such as: tetr-butyl isocyanide or 2,5-dimethoxybenzyl isocyanide. The observed results are especially important in the case of the increasing resistance of bacteria to various drugs and antibiotics.     

Structure,Properties, and Corrosion Behavior of Ti-Rich TiZrNbTa Medium-Entropy Alloys with β+α″+α′ for Biomedical Application

Five Ti-rich β+α″+α′ Ti–Zr–Nb–Ta biomedical medium-entropy alloys with excellent mechanical properties and corrosion resistance were developed by considering thermodynamic parameters and using the valence electron concentration formula. The results of this study demonstrated that the traditional valence electron concentration formula for predicting phases is not entirely applicable to medium-entropy alloys. All solution-treated samples with homogeneous compositions were obtained at a low temperature (900 °C) and within a short period (20 min). All solution-treated samples exhibited low elastic moduli ranging from 49 to 57 GPa, which were significantly lower than those of high-entropy alloys with β phase. Solution-treated Ti₆₅–Zr₂₉–Nb₃–Ta₃ exhibited an ultra-high bending strength (1102 MPa), an elastic recovery angle (>30°), and an ultra-low elastic modulus (49 GPa), which are attributed to its α″ volume fraction as high as more than 60%. The pitting potentials of all samples were higher than 1.8 V, and their corrosion current densities were lower than 10^–5 A/cm³ in artificially simulated body fluid at 37 °C. The surface oxide layers on Ti₆₅–Zr₂₉–Nb₃–Ta₃ comprised TiO₂, ZrO₂, Nb₂O₅, and Ta₂O₅ (as discovered through X-ray photoelectron spectroscopy) and provided the alloy with excellent corrosion and pitting resistance.     

In Situ Tensile Deformation and Mechanical Properties of α Platelets TC21 Alloy

The present study was focused on the relationship between an α platelet microstructure and the properties of TC21 alloy, and the tensile deformation process was revealed by in situ observation. To obtain the α platelet microstructures, the samples were administered a solution treatment (1000 °C for 15 min) and then cooled to room temperature by different cooling methods (furnace cooling (FC), open-door furnace cooling (OFC), air cooling (AC), and water quench (WQ), corresponding to an increased cooling rate). It is found that α platelets become thinner and colonies become narrower with the increase in cooling rate. The formation of the platelet microstructure is based on the preferred Burgers orientation relationship of {110}_β//{0001}_α and <111>_β//<112¯0>_α. The α platelets orientation changes with the cooling rate. These differences in α platelets thickness and orientation result in the excellent ductility of the sample with thick platelets and the high strength of the samples with thin platelets. During the in situ tensile deformation process, the crack propagation path is deflected in the presence of grain boundaries, α platelets, and α colonies with different orientations. The fracture of the sample with thick α platelets shows better ductility compared to those with thin α platelets.     

The Effect of ECAP Processing Conditions on Microstructural Evolution and Mechanical Properties of Pure Magnesium—Experimental,Mathematical Empirical and Response Surface Approach

In this study, a quantitative evaluation approach was used to investigate how certain ECAP processing parameters affect the microstructural evolution, Vicker’s microhardness values and tensile properties of pure Mg. The ECAP processing parameters were number of passes, ECAP die channel angle and processing route type. The response surface methodology (RSM) technique was used to design 16 runs of the experiment using Stat-Ease design expert software. Billets of pure Mg were processed up to four passes of routes Bc, A and C at 225 °C. Two ECAP dies were used with internal channel angles of 90° and 120°. Experimental findings were used to establish empirical models to assess the influence of the ECAP processing parameters on grain size and mechanical properties of ECAPed billets. The established relationships were examined and validated for their adequacy and significance using ANOVA as well as several statistical criteria. Response surface plots and contour graphs were established to offer better understanding of the intended relationships. In addition, the optimum processing parameters for grain size, hardness values and tensile properties were defined. Both experimental results and the theoretical model revealed that route Bc is the most effective route in grain refining. The experimental findings showed that four passes of route Bc through the die channel angle 90° revealed a significant reduction in the grain size by 86% compared to the as-annealed counterparts. Similar to the grain size refining, four-passes processing through the ECAP die with an internal channel angle of 90° leads to improved Vicker’s microhardness values. Additionally, four passes of route Bc using the 90° die angle recorded a significant HV increase at the edge and central areas by 112% and 78%, respectively, compared to the as-annealed counterpart. On the other hand, according to the optimization findings, two passes of route Bc using a die angle of 120° resulted in the best ultimate tensile strength for pure Mg, whereas four passes of route Bc revealed the optimum ductility at fracture.     

Influence of Anomalous Changes in the Crystal Structure on the Transport Properties of YbNi1−xCuxAl Series of Alloys

Results of the transport properties of the YbNi_1−xCu_xAl (x = 0, 0.2, 0.5, 0.8 and 1.0) series of alloys are reported. The previous analysis of X-ray diffraction patterns indicates that all compounds crystallize in the hexagonal ZrNiAl structure with a linear behavior of the unit cell volume as a function of the Cu concentration (x). This is not found in the unit cell parameters, showing a discontinuity between x = 0.5 and 0.8. Such discontinuities affect the behavior of the electrical resistivity, in which the position of the minimum temperature changes from 95 K to 175 K, and a rise in the low temperature slope in the magnetic contribution (with -lnT dependence) from 21 μΩcm to 212 μΩcm is observed. In addition, the electronic coefficient of the specific heat increases almost twofold from 125 mJ/mol·K² (x = 0.5) to 246 mJ/mol·K² (x = 0.8). These changes are attributed to the variation of the distance between Yb and transition metals (Ni and Cu) along the series and the different electronic properties of the transition metals (Ni and Cu).     

Comparison of Physicochemical Properties of Fly Ash Precursor,Na-P1(C) Zeolite–Carbon Composite and Na-P1 Zeolite—Adsorption Affinity to Divalent Pb and Zn Cations

Considering the growing needs of environmental remediation, new effective solutions should be sought. Therefore, the adsorbed amounts of heavy metal ions, such as lead(II) and zinc(II), on the surface of high-carbon fly ash (HiC FA), zeolite-–carbon composite (Na-P1(C)) and pure zeolite (Na-P1), were investigated. The applied solids were characterized using the following techniques: XRD, SEM-EDS, TEM, porosimetry, SLS, electrophoresis and potentiometric titration. The heavy metal concentration in the probes was determined by applying ICP-OES spectroscopy. Adsorption/desorption and electrokinetic measurements were performed in the systems containing one or two adsorbates. The obtained results indicated that Pb(II) ions are adsorbed in larger amounts on the investigated solid surface due to the molecular sieving effect. The largest adsorption capacity relative to lead(II) ions was observed for pure Na-P1 zeolite (407 mg/g). The simultaneous presence of Pb(II) + Zn(II) mixed adsorbates minimally affects the amount of adsorbed Pb(II) ions and causes a significant decrease of Zn(II) ion adsorption (in comparison with analogous systems containing single adsorbates). It was also shown that all solids can be efficiently regenerated using hydrochloric acid. Thus, the selected pure zeolite can be successfully applied in soil remediation or other purifying technologies as an effective Pb(II) adsorbent.