Compositional Dependence of Magnetocrystalline Anisotropy in Fe-, Co-, and Cu-Alloyed Ni-Mn-Ga

The key for the existence of magnetic induced reorientation is strong magnetocrystalline anisotropy, i.e., the coupling between ferroelastic and ferromagnetic ordering. To increase the transformation temperatures and thus functionality, various elemental alloying in Ni-Mn-Ga is tried. We analyzed more than twenty polycrystalline alloys alloyed by small amount (up to 5atom%) of transitional metals Co, Fe, Ni, and Cu for the value of magnetic anisotropy in search of general trends with alloying. In agreement with previous reports, we found that maximum anisotropy occurs at stoichiometric Ni2MnGa and any alloying decreases its value. The strongest decrease of the anisotropy is observed in the case where the alloyed elements substitute Ga.

Effect of ZnO on Properties of Gels for Heritage Objects Conservation

One of the current research objectives is the development of new films for the conservation of glass heritage objects. The value of historical glass objects is given by the technology and raw materials used in production as well as their transparency and color. Their colors are correlated with oxide composition rich in transitional metals, which decrease resistance of corrosive agents from the atmosphere. In this paper, SiO2-ZnO gels have been designed to protect historical glass objects. The sol–gel method used to obtain gels is a powerful tool for functionalizing different materials. An important functionalization is the antibacterial activity. By applying a gel, the coated material is able to decrease the growth of bacteria. After deposition, some gels must be strengthened by heat treatment. The effect of ZnO content (10 mol% and 20 mol%) on the properties of the studied gels was investigated by Differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and antibacterial tests. Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, and the halotolerant bacterium, Virgibacillus halodenitrificans, isolated from a salt crystal from Unirea mine, Slănic Prahova, Romania, were used. The gel Gel 2 (SiO2-ZnO (20 mol%)) showed the best properties.

Demonstration of Near Edge X-ray Absorption Fine Structure Spectroscopy of Transition Metals Using Xe/He Double Stream Gas Puff Target Soft X-ray Source

A near 1-keV photons from the Xe/He plasma produced by the interaction of laser beam with a double stream gas puff target were employed for studies of L absorption edges of period 4 transitional metals with atomic number Z from 26 to 30. The dual-channel, compact NEXAFS system was employed for the acquisition of the absorption spectra. L1–3 absorption edges of the samples were identified in transmission mode using broadband emission from the Xe/He plasma to show the applicability of such source and measurement system to the NEXAFS studies of the transition metals, including magnetic materials.

Determination and Removal of Phosphate and Nitrate from the Ground and Surface Water at the Three Counties of Guyana

Standard analytical procedures that are based on colourimetry facilitated the determination of PO43- and NO3- in the ground and surface waters from the three (3) counties of Guyana. Phosphates and nitrates beyond their permissible levels in natural waters can pose significant threats to the aquatic environment, its inhabitants, and the health of humans and terrestrial animals. For this reason, this study aims to investigate the use of metal (nickel, cadmium, cobalt) ferrocyanides (octahedral complexes that facilitate adsorption of anions primarily on its two divalent transitional metals) as adsorbents to facilitate the removal of the aforementioned anions. Results revealed that nickel ferrocyanide is the most effective adsorbent for treating ground and surface waters that contain high levels of PO43-, while it was also the most effective adsorbent for treating surface waters that contained NO3-. Fixed volumes of water samples were treated with 50 mg, 100 mg, and 150 mg of the adsorbent. The correlation coefficient computations revealed that they were instances of both positive and negative correlations, which implied that increasing adsorbent dosage resulted in increased adsorption and other instances decreased adsorption, respectively. This occurrence went against literature, possible reasons for this are explained in detail within the discussion portion of the manuscript. Adsorption isotherms and Langmuir plots were used to facilitate adsorption studies, in various instances, the generic appearance of these isotherms was not observed, possible reasons for this occurrence are also explained in more detail within the article. Based on observations within the article, the use of cobalt ferrocyanide for treating groundwater and removing PO43- is not recommended, while cadmium ferrocyanide is not recommended to be used to facilitate the removal of NO3-, due to the possible formation of Co3(PO4)2 and Cd(NO3)2, respectively, which consequently affected the results. Technologies like those studied in this research project should be explored and studied more in-depth (particularly with regards to the stability of the adsorbents) with regards to the treating of ground and surface water supplies, to facilitate the removal of PO43- and NO3-, since the results observed, though on a small scale, can be seen to move us closer towards a green and sustainable environment, inclusive of safeguarding the health of the Worlds’ people and expanding the scope of cost-effective and simple methods that aid in the removal of anions from natural waters.

Influence of impurities of the transitional metals Fe, Ni, and Co on the hydrolysis kinetics of BH− 4 ions in alkaline solutions

The influence of small amounts of the Fe, Co, and Ni impurities on the spontaneous hydrolytic process of borohydride was studied within a temperature range of 60–100°C. The object under study was a simulated solution containing 9.53 M of OH− ions and 0.14 M of BH− 4 ions, used as a fuel for borohydride fuel cells. The rate constant k of borohydride hydrolysis for a small amount of impurities at different temperature was estimated. The lowest non-accelerating concentrations of the impurities were established (∼10 ppm for iron; ∼1 ppm for cobalt). The strongest accelerating effect on the hydrolysis of BH− 4 ions was rendered by nickel impurities: self-hydrolysis was accelerated by 1.2 times for 1 ppm Ni. The ambiguous trend of the kinetic curves does not allow to accurately estimate the activation energy; however, the increased temperature enhances the catalytic effect of hydrolysis acceleration according to Arrhenius’ equation.

Evolution of the Microstructure and Mechanical Properties of cBN-Based Cutting Tools With Silicides Compounds as Binder Phase

Silicide based compounds are widely used for coatings due to their high melting temperature, oxidation resistance and moderate density. Employment of binders based on silicides of transitional metals can provide cBN-based cutting tools with higher chemical stability and better performance. The relationship between phase composition, microstructure and mechanical properties of novel polycrystalline cubic boron nitride (PcBN) materials were investigated. Three series of PcBN samples were made by high pressure high temperature (HPHT) sintering. Silicides of chromium – CrSi2, vanadium – VSi2 and molybdenum MoSi2 were used as a binder phase in each case, while aluminum was introduced to the mixture as an oxygen getter. During HPHT sintering at temperatures above 1850 ∘C the formation of borides of binder phase were observed in cases with VSi2 and MoSi2. For system with CrSi2 binder, temperature of boride formation was found to be lower – 1600 ∘C. Materials with MoSi2 binder phase demonstrated the highest level of microhardness. Performance of materials were investigated in conditions of machining of stainless steel AISI 316L and Inconel 718.

Application of Readily Available Metals for C-H Activation

Catalytic C-H activation is a powerful method for organic synthesis. In recent years, scientists have made great progress by developing transitional metals for catalyzing CH functionalization reaction. In this review, we summarized and highlighted recent progress in C-H activation with copper, cobalt, iron, manganese, and nickel as catalysts.

Unleash electron transfer in C–H functionalization by mesoporous carbon-supported palladium interstitial catalysts

The functionalization of otherwise unreactive C–H bonds adds a new dimension to synthetic chemistry, yielding useful molecules for a range of applications. Arylation has emerged as an increasingly viable strategy for functionalization of heteroarenes which constitute an important class of structural moieties for organic materials. However, direct bisarylation of heteroarenes to enable aryl-heteroaryl-aryl bond formation remains a formidable challenge, due to the strong coordination between heteroatom of N or S and transitional metals. Here we report Pd interstitial nanocatalysts supported on ordered mesoporous carbon as catalysts for a direct and highly efficient bisarylation method for five-membered heteroarenes that allows for green and mild reaction conditions. Notably, in the absence of any base, ligands and phase transfer agents, high activity (turn-over frequency, TOF, up to 107 h−1) and selectivity (>99%) for the 2,5-bisarylation of five-membered heteroarenes are achieved in water. A combination of characterization reveals that the remarkable catalytic reactivity here is attributable to the parallel adsorption of heteroarene over Pd clusters, which breaks the barrier to electron transfer in traditional homogenous catalysis and creates dual electrophilic sites for aryl radicals and adsorbate at C2 and C5 positions. The d-band filling at Pd sites shows a linear relationship with activation entropy and catalytic activity. The ordered mesopores facilitate the absence of a mass transfer effect. These findings suggest alternative synthesis pathways for the design, synthesis and understanding of a large number of organic chemicals by ordered mesoporous carbon supported palladium catalysts.

ON THE RELATIONSHIP OF ANTHROPOGENIC AIR POLLUTION BY PARTICULATE MATTER WITH CANCER RISK

In the review the author highlights contemporary concepts about the relation between the air pollution by the particulate matter (PM) and human morbidity and mortality due to oncological diseases (OD). The author used materials of the articles indexed in the PubMed and RISC databases. The role of air pollution by PM as a risk factor of carcinogenesis in dependence on size, origin, chemical composition and concentration in air is discussed. PM of road-transport origin contains transitional metals acknowledged as most dangerous and is the result the operational wear of motor transport, road surface, and vehicle emissions. Long-term exposure to PM with an aerodynamic diameter ≤2.5 increases risk of appearance of OD of different localization. Dose-dependent action of PM was established. Reduction in air pollution by PM is accompanied by decrease of premature mortality of population, including from OD, and it can be examined as a modifiable risk factor. The results of the meta-analysis of literature data about the economic damage, caused by morbidity and mortality from OD led to the conclusion that reduction in PM concentration is the most realistic and effective method to decrease these social and economic losses. The accumulated carcinogenic risk provides for the lifelong probability of the development of OD, which requires the active medical examination of workers after the curtailment of work with carcinogens for early diagnostics and treatment of OD. The important preventive measure is to decrease the level of air pollution independently on their initial concentration.

On the relationship of anthropogenic air pollution by particulate matter with cancer risk

In the review the author highlights contemporary concepts about the relation between the air pollution by the particulate matter (PM) and human morbidity and mortality due to oncological diseases (OD). The author used materials of the articles indexed in the PubMed and RISC databases. The role of air pollution by PM as a risk factor of carcinogenesis in dependence on size, origin, chemical composition and concentration in air is discussed. PM of road-transport origin contains transitional metals acknowledged as most dangerous and is the result the operational wear of motor transport, road surface, and vehicle emissions. Long-term exposure to PM with an aerodynamic diameter ≤2.5 increases risk of appearance of OD of different localization. Dose-dependent action of PM was established. Reduction in air pollution by PM is accompanied by decrease of premature mortality of population, including from OD, and it can be examined as a modifiable risk factor. The results of the meta-analysis of literature data about the economic damage, caused by morbidity and mortality from OD led to the conclusion that reduction in PM concentration is the most realistic and effective method to decrease these social and economic losses. The accumulated carcinogenic risk provides for the lifelong probability of the development of OD, which requires the active medical examination of workers after the curtailment of work with carcinogens for early diagnostics and treatment of OD. The important preventive measure is to decrease the level of air pollution independently on their initial concentration.