Influence of Si, Cu, B, and Trace Alloying Elements on the Conductivity of the Al-Si-Cu Alloy

The influence of Si, Cu, B, and trace alloying elements on the conductivity of aluminum die cast 12 (ADC12) alloy was investigated. The conductivity decreased linearly with increasing volume fraction of the Si phase attributed to a linear decrease of the volume of the more conductive Al phase through a rule of mixtures. The conductivity also decreased with increasing Cu content, between 0~3%. The conductivity increased with increasing B content, reached the peak at 0.02% B and thereafter decreased somewhat. The mechanism was that B reacted with the transition element in the Al phase to form boride, decreasing the transition element concentration in the Al lattice, and decreasing the lattice constant. The thermal conductivity, λ, was related to the electrical conductivity, σ, by means of λ=LTσ+λg, where L is the apparent Lorentz constant, 1.86 × 10−8; T is the absolute temperature, 293 K; λg is the lattice conductivity, 42.3 W/(m·K).

Спонтанный спиновый магнетизм донорных электронов проводимости гибридизированных состояний кристалла, образованных системой примесных атомов 3d-элементов низкой концентрации (<1 at.%)

The given work is devoted to the experimental proof of existing the spontaneous spin polarization of the donor electron system of 3d-transition element impurity atoms of low concentration (<1 at.%) in a mercury selenide crystal. For this purpose there have been measured the dependences of the magnetization on the magnetic field strength. As a result of the analysis of the obtained dependences, there were extracted the impurity contributions, which are described by the magnetization curves typical of the ferromagnets, and by the magnetic parameters conforming to the spontaneous magnetism of the systems under study, which are unambiguously related to the donor conduction electrons of the outer d-shells of impurity atoms. By its nature, according to the developed theoretical concepts, the spontaneous spin polarization manifests itself in exchange interaction, taking place in hybridizing the electronic states of the impurity atom and the conduction band ones of the crystal.

Temporal variation of planetary iron as a driver of evolution

Iron is an irreplaceable component of proteins and enzyme systems required for life. This need for iron is a well-characterized evolutionary mechanism for genetic selection. However, there is limited consideration of how iron bioavailability, initially determined by planetary accretion but fluctuating considerably at global scale over geological time frames, has shaped the biosphere. We describe influences of iron on planetary habitability from formation events >4 Gya and initiation of biochemistry from geochemistry through oxygenation of the atmosphere to current host–pathogen dynamics. By determining the iron and transition element distribution within the terrestrial planets, planetary core formation is a constraint on both the crustal composition and the longevity of surface water, hence a planet’s habitability. As such, stellar compositions, combined with metallic core-mass fraction, may be an observable characteristic of exoplanets that relates to their ability to support life. On Earth, the stepwise rise of atmospheric oxygen effectively removed gigatons of soluble ferrous iron from habitats, generating evolutionary pressures. Phagocytic, infectious, and symbiotic behaviors, dating from around the Great Oxygenation Event, refocused iron acquisition onto biotic sources, while eukaryotic multicellularity allows iron recycling within an organism. These developments allow life to more efficiently utilize a scarce but vital nutrient. Initiation of terrestrial life benefitted from the biochemical properties of abundant mantle/crustal iron, but the subsequent loss of iron bioavailability may have been an equally important driver of compensatory diversity. This latter concept may have relevance for the predicted future increase in iron deficiency across the food chain caused by elevated atmospheric CO2.

Sub-chronic oral exposure of tungsten induces markers of kidney injury

Tungsten is a naturally occurring transition element used in a broad range of applications. As a result of its extensive use, we are increasingly exposed to tungsten from our environment, including potable water, since tungsten can become bioaccessible in ground sources. The kidneys are particularly susceptible to tungsten exposure as this is the main site for tungsten excretion. In this study, we investigated the prolonged effects of tungsten on the kidneys and how this may impact injury and function. When mice were exposed to tungsten in their drinking water for 1-month, kidney function had not significantly changed. Following 3-month exposure, mice were presented with deterioration in kidney function as determined by serum and urine creatinine levels. During 3-months of tungsten exposure, murine kidneys demonstrated significant increases in the myofibroblast marker ⍺SMA, and extracellular matrix products: fibronectin, collagen, and matricellular proteins. In addition, Masson's trichrome and H&E staining revealed an increase in fibrotic tissue and vacuolization of tubular epithelial cells, respectively, from kidneys of tungsten-treated mice, indicative of renal injury. In vitro treatment of kidney fibroblasts with tungsten led to increased proliferation and upregulation of Transforming Growth Factor Beta 1 (TGFβ1), which was consistent with the appearance of fibroblast-to-myofibroblast transition (FMT) markers. Our data suggest that continuous exposure to tungsten impairs kidney function that may lead to the development of chronic kidney disease (CKD).

Effect of Boronizing Treatment on the Conductivity of a High-Conductivity and Heat-Resisting Al-Zr Alloy Conductor Material

The effect of boronizing treatment on the conductivity of a high-conductivity and heat-resistant Al-Zr alloy conductor material was studied. The results showed that the conductivity of industrial pure Al containing transition element (Ti, V, Cr, Mn)>0.01 wt % (mass fraction, the same below) was improved to a certain extent by using boronizing treatment to remove transition metal elements through the formation of borides. Using the boronizing treatment, B can react with transition elements to form blocky (Ti, V, Fe)B2 and flocculent (Ti, V, Fe, Zr)B2. The boronizing treatment makes Ti and V out of the solid solution state, form borides and finally deposit to the bottom of the furnace, thus significantly improving the conductivity of the ingot. In addition, Cr and Mn were not found in the borides at the bottom of the furnace. However, for the high-conductivity and heat-resisting Al-Zr alloy conductor material, B will have poison effects on Zr during boronizing treatment, thus reducing the heat-resistance of the alloy. Therefore, in the preparation process of high-conductivity and heat-resistant Al-Zr alloy conductor material, the converter process should be added after boronizing treatment to ensure that the Al-Zr alloy conductor material has good heat-resistance and conductivity at the same time.

Physics of Spin-Orbit-Coupled Oxides

Prior to 2010, most research on the physics and chemistry of transition metal oxides was dominated by compounds of the 3d-transition elements such as Cr, Mn, Fe, Co, Ni, and Cu. These materials exhibited novel, important phenomena that include giant magnetoresistance in manganites, as well as high-temperature superconductivity in doped La2CuO4 and related cuprates. The discovery in 1994 of an exotic superconducting state in Sr2RuO4 shifted some interest toward ruthenates. Moreover, the realization in 2008 that a novel variant of the classic Mott metal-insulator transition was at play in Sr2IrO4 provided the impetus for a burgeoning group of studies of the influence of strong spin-orbit interactions in “heavy” (4d- and 5d-) transition-element oxides. This book reviews recent experimental and theoretical evidence that the physical and structural properties of 4d- and 5d-oxides are decisively influenced by strong spin-orbit interactions that compete or collaborate with comparable Coulomb, magnetic exchange, and crystalline electric field interactions. The combined effect leads to unusual ground states and magnetic frustration that are unique to this class of materials. Novel couplings between the orbital/lattice and spin degrees of freedom, which lead to unusual types of magnetic order and other exotic phenomena, challenge current theoretical models. Of particular interest are recent investigations of iridates and ruthenates focusing on strong spin-orbit interactions that couple the lattice and spin degrees of freedom.

A Dual Role of Vanadium in Environmental Systems—Beneficial and Detrimental Effects on Terrestrial Plants and Humans

The importance of vanadium (V) in the functioning of land systems is extremely diverse, as this element may exert both positive and harmful effects on terrestrial organisms. It recently become considered an element of beneficial character with a range of applications for human welfare. The health-ameliorative properties of this transition element depend on its degree of oxidation and on optimal concentration in the target cells. It was found that a similar relationship applies to vascular plants. However, excessive amounts of vanadium in the environment contaminate the soil and negatively affect the majority of living organisms. A significantly elevated level of V results in the destabilization of plant physiological balance, slowing down the growth of biomass which significantly reduces yield. In turn, low doses of the appropriate vanadium ions can stimulate plant growth and development, exert cytoprotective effects, and effectively enhance the synthesis of some biologically active compounds. We present the scientific achievements of research teams dealing with such topics. The issues discussed concern the role of vanadium in the environment, particular organisms, and highlight its dualistic influence on plants. Achievements in the field of V bioremediation, with the use of appropriately selected microorganisms and plant species, are emphasized.

Techniques in the synthesis of organometallic compounds of Hafnium

Hafnium is a transition metal and it is the 45th most abundant transition element present on the earth. Hafnium has been successfully alloyed with several metals including titanium, iron, and niobium. Hafnium complexes are less active olefin polymerization catalysts. In the current review synthesis of hafnium complexes involving bonding through different linkages like “carbon, nitrogen, oxygen, carbon and oxygen, nitrogen and cobalt nitrogen and oxygen, nitrogen and phosphorus, nitrogen and sulfur, phosphorus and carbon, phosphorus and oxygen, sulfur carbon and oxygen, carbon–nitrogen and oxygen, carbon–nitrogen and phosphorus, carbon–nitrogen oxygen, sulfur and phosphorus, carbon–oxygen phosphorus and nitrogen”. The commonly used solvents for the synthesis of Hafnium complexes are tetrahydrofuran, n-hexane, and toluene, etc. These complexes were mostly reported at different temperatures ranges from −35 to 110 °C with continuous stirring, according to the nature of ligands. An overview of techniques in the synthesis of Hafnium complexes through various routes has been compiled.

SPECTROPHOTOMETRIC COLOR DETERMINATION OF CERAMIC PIGMENTS FOR CONSTRUCTION CERAMICS AND REGIONAL INNOVATION SYSTEM

The purpose of this work is the spectrophotometric determination of the color of ceramic pigments for the development of technology for the production of high-quality ceramic paints of a wide color palette for decorating building ceramics, porcelain and faience products. In this regard, using the principles of heterovalent isomorphic substitution of atoms in crystals, the compositions of ceramic pigments were designed on the basis of the anorthite derivatives containing transition elements with the general formula Са1-хMexAl2+xSi2-xО8, where calcium and silicon ions were replaced by aluminum and transition element, Ме – Cо, Ni, Fe, Cr. The color characteristics were taken on the UV-2600 spectrophotometer with «UV Probe» software. Measurement of wavelengths was in the range of -220-1400 nm. For Fe3+ with tetrahedral coordination, the brown color is due to the d–d transition. The absorption wavelengths of the samples corresponded to 758-283 nm. Со2+ is characterized by a coordination number of 4, the wavelengths of the absorbed light are 1328, 776, 625, 551, and 408 nm. In this case, the brightness varies from 5 to 64%. The color of the samples is violet-blue. For the yellow-green complex [NiО6], the absorption bands are located at ⅄ = 894, 693, 622, 385. The absorption spectra of chromium-containing pigments are characterized by the presence of maxima in the region of 536, 408, 310 nm, which corresponds to the green region of the spectrum

Effects of Transition Element Additions on the Interfacial Interaction and Electronic Structure of Al(111)/6H-SiC(0001) Interface: A First-Principles Study

In this work, the effects of 20 transition element additions on the interfacial adhesion energy and electronic structure of Al(111)/6H-SiC(0001) interfaces have been studied by the first-principles method. For pristine Al(111)/6H-SiC(0001) interfaces, both Si-terminated and C-terminated interfaces have covalent bond characteristics. The C-terminated interface has higher binding energy, which is mainly due to the stronger covalent bond formed by the larger charge transfer between C and Al. The results show that the introduction of many transition elements, such as 3d transitional group Mn, Fe, Co, Ni, Cu, Zn and 4d transitional group Tc, Ru, Rh, Pd, Ag, can improve the interfacial adhesion energy of the Si-terminated Al(111)/6H-SiC(0001) interface. However, for the C-terminated Al(111)/6H-SiC(0001) interface, only the addition of Co element can improve the interfacial adhesion energy. Bader charge analysis shows that the increase of interfacial binding energy is mainly attributed to more charge transfer.