Earth Metal Research Articles

Novel inhibitors of eukaryotic elongation factor 2 kinase: In silico, synthesis and in vitro studies

Eukaryotic elongation factor 2 kinase (eEF2K) is an unusual alpha kinase whose expression is highly upregulated in various cancers and contributes to tumor growth, metastasis, and progression. More importantly, eEF2K expression is associated with poor clinical outcome and shorter patient survival in breast, lung and ovarian cancers. Therefore, eEF2K is an emerging molecular target for development of novel targeted therapeutics and precision medicine in solid cancers. Currently, there are not any available potent and specific eEF2K inhibitors for clinical translation. In this study, we designed and synthesized a series of novel compounds with coumarin scaffold with various substitutions and investigated their effects in inhibiting eEF2K activity using in silico approaches and in vitro studies in breast cancer cells. We utilized an amide substitution at position 3 on the coumarin ring with their pharmacologically active groups containing pyrrolidine, piperidine, morpholine and piperazine groups with (CH2)2 bridged for aliphatic amides. Due to their ability to form covalent binding to the target enzyme, we also investigated the effects of boron containing groups on functionalized coumarin ring (3 compounds) and designed novel aliphatic and aromatic derivatives of coumarin scaffolds (10 compounds) and phenyl ring with boron groups (4 compounds). The Glide/SP module of the Maestro molecular modeling package was used to perform in silico analysis and molecular docking studies. According to our combined results, structure activity relationship (SAR) was performed in detail. Among the newly designed, synthesized, and tested compounds, our in vitro findings revealed that several compounds displayed a highly effective eEF2K inhibition at submicromolar concentrations in in vitro breast cancer cells. In conclusion, we identified novel compounds that can be used as eEF2K inhibitors and that they should be further evaluated by in vivo preclinical tumor models studies for antitumor efficacy and clinical translation.

Direct installation of boron groups offers boost to medicinal chemistry

Direct installation of boron groups offers boost to medicinal chemistry

A new topological semimetal candidate: SmMnBi2

The new compound SmMnBi2 has been synthesized by the self-flux method and shown to crystallize in space group I4/mmm with a = 4.5054 (4) Å, c = 20.5914 (19) Å and Z = 4. Its structure comprises two-dimensional square Mn-nets layers, puckered rock-salt-like SmBi slabs and two-dimensional square Bi-nets layers, alternating along the c axis in an …Mn-net–SmBi slab–Bi-net–SmBi slab–Mn-net… sequence. Surprisingly, the atomic arrangement differs from its neighboring compound EuMnBi2 which has similar layers but with a different stacking arrangement. This gives rise to edge-shared square planar MnBi4 polyhedral layers in SmMnBi2 while EuMnBi2 has edge-shared MnBi4 tetrahedral layers. The MMnX 2 (M = alkaline earth/rare earth metals, X = Sb/Bi) family has emerged as topological Dirac or Weyl semimetal candidates, all of them sharing similar structural features. Although SmMnBi2 has a different stacking arrangement to EuMnBi2, its layer structure still makes it a topological Dirac or Weyl semimetal candidate.

Recent Advances in ZnO-Based Carbon Monoxide Sensors: Role of Doping.

Monitoring and detecting carbon monoxide (CO) are critical because this gas is toxic and harmful to the ecosystem. In this respect, designing high-performance gas sensors for CO detection is necessary. Zinc oxide-based materials are promising for use as CO sensors, owing to their good sensing response, electrical performance, cost-effectiveness, long-term stability, low power consumption, ease of manufacturing, chemical stability, and non-toxicity. Nevertheless, further progress in gas sensing requires improving the selectivity and sensitivity, and lowering the operating temperature. Recently, different strategies have been implemented to improve the sensitivity and selectivity of ZnO to CO, highlighting the doping of ZnO. Many studies concluded that doped ZnO demonstrates better sensing properties than those of undoped ZnO in detecting CO. Therefore, in this review, we analyze and discuss, in detail, the recent advances in doped ZnO for CO sensing applications. First, experimental studies on ZnO doped with transition metals, boron group elements, and alkaline earth metals as CO sensors are comprehensively reviewed. We then focused on analyzing theoretical and combined experimental–theoretical studies. Finally, we present the conclusions and some perspectives for future investigations in the context of advancements in CO sensing using doped ZnO, which include room-temperature gas sensing.

Stepping Out of Transition Metals: Activating the Dual Atomic Catalyst through Main Group Elements

AbstractIn recent years, investigations into atomic catalysts has accelerated significantly. Although different atomic catalysts have been developed, the introduction of main group elements is rarely considered. In this work, the possibility of introducing alkaline/alkaline earth metals (AAEM), post‐transition metal (Post‐TM), and metalloids to form stable graphdiyne‐based dual atomic catalysts (GDY‐DAC) is revealed. The main group elements not only act as a promising separator to improve the loading of DACs but also activate the alkyl chains to facilitate the electroactivity of GDY‐DAC. Most importantly, the main group elements in the GDY‐DAC do not affect the electroactivity of transition or lanthanide metals and even enable subtle modulations on the electronic structures. The p band center is a significant descriptor to modulate the electroactivity in oxides while their applications in the atomic catalysts are unclear. With the further evaluations of machine learning, it is found that the involvements of s‐orbitals and p‐orbitals perturb the prediction accuracies of both formation energies and p‐band center, especially for the AAEM. This work supplies insights that are expected to aid progress in designing main group elements‐based atomic catalysts, which opens a new avenue in designing advanced electrocatalysts.

Mixture designs to investigate the role of alkali and alkaline earth cations on composition-structure-property relationships in ternary borate glass networks

Sixteen borate glass compositions, modified with K2O and SrO, were established using a design of mixtures approach and were subjected to chemical and physical characterization (11B MAS NMR, density, and glass transition temperature (Tg)). The analysis intended to establish the influence of K2O and SrO on the composition-structure-property relationships for borate glass networks. The effects of γ-radiation on the glass networks were also examined to determine the impact that sterilization may have on the glass properties. Structural analysis showed that both K2O and SrO influenced the fraction of three- and four-fold coordinated boron groups independent of the cation. Thermal analysis of the glasses revealed that SrO significantly increases the glass transition temperature while both SrO and K2O have comparable impacts on glass stability. These data suggest that Sr2+ cations cross-link the networks. Contrastingly, K+ appears to stabilize B4 structures. All sixteen compositions retained their chemical and physical characteristics following sterilization.

Special Issue: Biochemical and Thermochemical Conversion Processes of Lignocellulosic Biomass Fractionated Streams

Global consumption of materials such as forest resources, fossil fuels, earth metals and minerals are expected to double in the next 30 years, while annual waste production is estimated to increase by approximately 70% by 2050 [...]

Local Delivery of Therapeutic Boron for Bone Healing Enhancement.

To evaluate if local delivery of boron can accelerate bone healing and examine if the bioactive salt impacts the osteogenic response of bone-derived osteoclasts and osteoblasts by the regulation of the Wnt/β-catenin pathway. Bilateral femoral cortical defects were created in 32 skeletally mature C57 mice. On the experimental side, boric acid (8 mg/kg concentration) was injected locally, whereas on the control side, saline was used. Mice were euthanized at 7, 14, and 28 days. MicroCT was used to quantify bone regeneration at the defect. Histological staining for alkaline phosphatase and tartrate-resistant acid phosphatase was used to quantify osteoblast and osteoclast activity, respectively. Immunohistochemical antibodies, β-catenin, and CD34 were used to quantify active β-catenin levels and angiogenesis, respectively. The boron group exhibited higher bone volume and trabecular thickness at 28 days on microCT. Both alkaline phosphatase activity and β-catenin activity was significantly higher in the boron group at 7 days. In addition, CD34 staining revealed increased angiogenesis at 14 days in boron-treated groups. We found boron to have no association with osteoclast activity. This study shows that local delivery of boron is associated with an increase in osteoblast activity at early phases of healing. The corresponding increase in β-catenin likely supports that boron increases osteoblast activity by the Wnt/β-catenin pathway. Increased angiogenesis at 14 days could be a separate mechanism of increasing bone formation that is independent of Wnt/β-catenin activation.

LANDSCAPE THERAPY FOR DISORDERS OF VISUAL PERCEPTION IN THE FAR NORTH

The development of the Russian Arctic continental shelf with the production of large volumes of oil products, the continuation of the functioning of the well-known mining enterprises of the Kola North for the extraction of rare earth and non-ferrous metals necessary for the country’s industry, the basing of the Northern Fleet as the most important component of the country’s defense capability require good health of all categories of workers and military personnel of the continental zone and the Arctic islands in the Far North. Psychoneurological diseases, including those associated with disorders of visual perception, developing on the basis of the «polar tension syndrome», acquire special significance in these conditions. Based on the results of generalization of the views existing in the scientific literature on the integrity of the mechanisms of visual perception, a two-dimensional classification of various forms of its variability has been developed, which can be used as a methodological basis for the construction of virtual and physical medical landscapes in recreational areas of military facilities, departmental sanatoriums and rest homes for prophylaxis and treatment of neuropsychiatric disorders caused by functional disorders of the body due to the impact of «polar load» and prolonged stay in closed technological spaces.

Investigation of the solubility of dust particles in soil solution at different temperatures (on the example of the tailings of the loparite ores' concentration)

A number of large mining enterprises are located on the territory of the Murmansk region. Dusting overburden dumps and tailings storage sites leads to a complex of long-term consequences for the environment. The output of the silty fraction (-0.071 mm) of "stale" tailings of loparite ore dressing (the first field of the tailing dump) is about 22 %. The investigated material is represented by nepheline, microcline, aegirine; loparite, analcime are diagnosed in impurity quantities; the average content of cerium, lanthanum, neodymium - rare earth elements of the light group - 0.18, 0.03 and 0.015 %, respectively. In laboratory conditions, a simulation of the ingress of a fine fraction of loparite ore dressing tailings into the soil has been carried out; the interaction of tailings material with distilled water and water extract from conditionally background soil at different temperatures has been studied. In the course of the study, it has been found that the introduction of dissolved organic matter intensifies the processes of destruction and partial dissolution of the aluminosilicate matrix of rock-forming minerals; an intensive transition of rare earth elements and heavy metals into soluble forms has been recorded. The research results indicate the ecological danger of the finely dispersed material of "stale" tailings of loparite ore dressing due to the ingress of dust particles into the soil and their interaction with soil waters.

Tune-out and magic wavelengths, and electric quadrupole transition properties of the singly charged alkaline-earth metal ions

In this paper, we present the tune-out and magic wavelengths of the Mg+, Ca+, Sr+ and Ba+ alkaline earth-metal ions by determining dynamic E1 polarizabilities. Furthermore, we have evaluated the electric quadrupole (E2) matrix elements of a large number of forbidden transitions using an all-order relativistic many-body method and compare them with the previously reported values for a few selective transitions. Compilation of both the E1 and E2 transition matrix elements, will now provide a more complete knowledge about the transition properties of the considered singly charged alkaline earth-metal ions. Similarly, the listed precise values of tune-out and magic wavelengths due to the dominant E1 polarizabilities can be helpful to conduct experiments using the above ions with reduced systematics. Therefore, all these data will be immensely useful for various applications for carrying out the high-precision experiments and laboratory simulations in atomic physics, and interpreting transition lines in the astrophysical observations. This work is a continuation of our earlier reported data on the electric dipole (E1) matrix elements and lifetimes of the metastable states of the alkaline earth ions in Kaur et al. (2021).

Graphene on two-dimensional hexagonal BN, AlN, and GaN: Electronic, spin-orbit, and spin relaxation properties

We investigate the electronic structure of graphene on a series of 2D hexagonal nitride insulators hXN, X = B, Al, and Ga, with DFT calculations. A symmetry-based model Hamiltonian is employed to extract orbital parameters and spin-orbit coupling (SOC) from the low-energy Dirac bands of proximitized graphene. While commensurate hBN induces a staggered potential of about 10 meV into the Dirac bands, less lattice-matched hAlN and hGaN disrupt the Dirac point much less, giving a staggered gap below 100 $\mu$eV. Proximitized intrinsic SOC surprisingly does not increase much above the pristine graphene value of 12 $\mu$eV; it stays in the window of (1-16) $\mu$eV, depending strongly on stacking. However, Rashba SOC increases sharply when increasing the atomic number of the boron group, with calculated maximal values of 8, 15, and 65 $\mu$eV for B, Al, and Ga-based nitrides, respectively. The individual Rashba couplings also depend strongly on stacking, vanishing in symmetrically-sandwiched structures, and can be tuned by a transverse electric field. The extracted spin-orbit parameters were used as input for spin transport simulations based on Chebyshev expansion of the time-evolution of the spin expectation values, yielding interesting predictions for the electron spin relaxation. Spin lifetime magnitudes and anisotropies depend strongly on the specific (hXN)/graphene/hXN system, and they can be efficiently tuned by an applied external electric field as well as the carrier density in the graphene layer. A particularly interesting case for experiments is graphene/hGaN, in which the giant Rashba coupling is predicted to induce spin lifetimes of 1-10 ns, short enough to dominate over other mechanisms, and lead to the same spin relaxation anisotropy as observed in conventional semiconductor heterostructures: 50\%, meaning that out-of-plane spins relax twice as fast as in-plane spins.

The diversity of the coordination bond generated a POSS-based fluorescent probe for the reversible detection of Cu(II), Fe(III) and amino acids.

In recent years, it has been found that Cu2+, Fe3+, and amino acids play an irreplaceable and subtle role in organisms and have attracted the considerable attention of many researchers. Therefore, it is vital to design visual indicators to reveal the relationships between metal ions and amino acids. However, there have been few reports on this vigorous subject. Fortunately, based on the different coordination effects between metal ions and boron groups, we have designed an accessible fluorescent probe (PSI-A). Borane was introduced as an ion-sensitive group to form a novel POSS-based fluorescent probe, which achieves fascinating performance, in situ dynamic multiple detection, excellent photostability, and enervative biological toxicity. PSI-A exhibited predominant selectivity and sensitivity to Cu2+/amino acids and Fe3+/amino acids sequence reactions in HepG2 cells and zebrafish. The fluorescence of PSI-A was quenched by Cu2+, which can be recovered by adding Asp, Ser, Arg, Ace or Trp. Additionally, the fluorescence of PSI-A quenched by Fe3+ can be restored after adding Asp. PSI-A is available to monitor Cu2+/amino acids and Fe3+/amino acids sequence reactions and can be repeated for at least three consecutive cycles without a fatigued performance. Therefore, this multifunctional fluorescent probe may have prospective application potentials in the biological field.

Harm and benefit of Khibiny mining waste

The article is focused on the assessment of the impact of mining waste on the environment. Mining waste (MW) is understood as mine (mining) dumps and dumps of processing plants (tailings dumps). The article also suggests considering MW as technogenic deposits of rare earth and precious metals, the development of which will allow solving many environmental, social and economic problems and using natural resources in a sustainable manner. The objects under study are located on the Kola Peninsula, within the Khibiny mountain range, and are the production assets of the Apatit Mining Complex. This enterprise develops the so-called deposits of the Khibiny Tundra, it also owns apatite-nepheline processing plants.

Back donation, intramolecular electron transfer and N-O bond scission targeting nitrogen oxyanion reduction: how can a metal complex assist?

A density functional theory exploration studies a range of ancillary coordinated ligands accompanying nitrogen oxyanions with the goal of promoting back donation towards varied nitrogen oxidation states. Evaluation of a suite of Ru and Rh metal complexes reveals minimum back donation to the κ1-nitrogen oxyanion ligand, even upon one-electron reduction. This reveals some surprising consequences of reduction, including redox activity at pyridine and nitrogen oxyanion dissociation. Bidentate nitrate was therefore considered, where ancillary ligands enforce geometries that maximize M-NOx orbital overlap. This strategy is successful and leads to full electron transfer in several cases to form a pyramidal radical NO32- ligand. The impact of ancillary ligand on degree of nitrate reduction is probed by comparing the powerful o-donor tris-carbene borate (TCB) to a milder donor, tris-pyrazolyl borate (Tp). This reveals that with the milder Tp donor, nitrate reduction is only seen upon addition of a Lewis base. Protonation of neutral and anionic (TCB)Ru(κ2-NO3) at both terminal and internal oxygens reveals exergonic N-O bond cleavage for the reduced species, with one electron coming from Ru, yielding a RuIII hydroxide product. Comparison of H+ to Na+ electrophile shows weaker progress towards N-O bond scission. Finally, calculations on (TCB)Fe(κ2-NO3) and [(TCB)Fe(κ2-NO3)]- show that electron transfer to nitrate is possible even with an earth abundant 3d metal.

Сезонные изменения химического состава воды сбросного канала Кольской атомной электростанции.

In this paper, the change in the chemical composition of water in the discharge channel in the spring and autumnperiodswas studied. An increase in the concentration of iron, alkali metals and a decrease in alkaline earth and non-ferrous metals in the autumn period compared to the spring period was revealed. It can be explained by changes in the discharge channel water temperature and acidity and also the presence of living organisms.

Alcohol Dehydration by Extractive Distillation with Use of Aminoethers of Boric Acid

Aminoethers of boric acid (AEBA) were studied as potential extractants for the separation of aqueous–alcoholic azeotropic mixtures by extractive distillation. The conditions of vapor–liquid equilibrium in aqueous solutions of ethanol and isopropanol in the presence of AEBA were studied. The division of AEBA molecules into group components was proposed, and previously unknown geometric parameters of the boron group and the energetic pair parameters of the boron group with the alkane group, ether group, amine-3d group, and alcohol group were determined within the framework of the Universal Functional Group Activity Coefficient (UNIFAC) model. The modeling of the extractive rectification process of an ethanol–water mixture with AEBA as extractant has been carried out. The dependences of the cost function on the extractant flow rate, the residual water content in it and the number of theoretical trays were obtained. A technological scheme for ethanol dehydration has been proposed, and its technological characteristics have been calculated.

A review on the migration and transformation of heavy metals influence by alkali/alkaline earth metals during combustion

Alkali/alkaline earth metals (AAEMs) are widely present in various solid fuels. During the combustion process, the AAEMs undergo complex physical and chemical reactions with heavy metals and other minerals in the fuel, thereby affecting the migration and transformation of heavy metals. This paper mainly introduced the influence of AAEMs on the migration and transformation of As, Se, Pb and Cr, including the influence of alkali metals and alkaline earth metals on the migration and transformation of heavy metals, and the influence of particle agglomeration and coherence on heavy metal emissions. AAEMs can inhibit the volatilization of heavy metals. The combination of alkali metals and Cl elements reduces the production of PbCl2. The presence of alkali metals is beneficial to improve the adsorption efficiency of kaolin for Pb. AAEMs can form stable compounds with As and Se. However, at the same time, it should be noted that in the partial combination products of AAEMs and Cr, Cr exists in a hexavalent state and has high toxicity. AAEMs play a role in promoting and inhibiting the occurrence of agglomeration, respectively. An appropriate content of alkali metals is beneficial to reduce the release of heavy metals. By summarizing the influence of AAEMs on the migration and transformation of heavy metals, it is hoped to provide ideas for reducing the harm of heavy metals.

Metal-free photoinduced C(sp3)-H borylation of alkanes.

Boronic acids and their derivatives are some of the most useful reagents in the chemical sciences1, with applications spanning pharmaceuticals, agrochemicals and functional materials. Catalytic C-H borylation is a powerful method for introducing these and other boron groups into organic molecules because it can be used to directly functionalize C-H bonds of feedstock chemicals without the need for substrate pre-activation1-3. These reactions have traditionally relied on precious-metal catalysts for C-H bond cleavage and, as a result, display high selectivity for borylation of aromatic C(sp2)-H bonds over aliphatic C(sp3)-H bonds4. Here we report a mechanistically distinct, metal-free borylation using hydrogen atom transfer catalysis5, in which homolytic cleavage of C(sp3)-H bonds produces alkyl radicals that are borylated by direct reaction with a diboron reagent. The reaction proceeds by violet-light photoinduced electron transfer between an N-alkoxyphthalimide-based oxidant and a chloride hydrogen atom transfer catalyst. Unusually, stronger methyl C-H bonds are borylated preferentially over weaker secondary, tertiary and even benzylic C-H bonds. Mechanistic studies indicate that the high methyl selectivity is a result of the formation of a chlorine radical-boron 'ate' complex that selectively cleaves sterically unhindered C-H bonds. By using a photoinduced hydrogen atom transfer strategy, this metal-free C(sp3)-H borylation enables unreactive alkanes to be transformed into valuable organoboron reagents under mild conditions and with selectivities that contrast withthose of established metal-catalysed protocols.

Crown ether-like structure in graphene quantum dots: Ultra-sensitive photoluminescence sensor for Ca2+ in vitro

Due to the weak coordination of alkaline−earth metal ions (such as Mg2+, Ca2+ and Sr2+), the design for corresponding fluorescent probes in vitro is much harder than those for heavy metal ions (such as Cu2+, Hg2+ and Pb2+). In this paper, the crown ether-like structure was introduced in graphene quantum dots (C-GQDs) via the hydrothermal treatment of alizarin. With the strong coordination of crown ether-like structure in C-GQDs’ lattice, C-GQDs show much lower detection limit to Ca2+ (2 pM) than that of surface modified graphene quantum dots (100 pM). Moreover, the selectivity of C-GQDs can be controlled by the size modulation of crown ether-like structure. Precursors with different structures were carried out to modulate the size of crown ether-like structure in C-GQDs. The obtained C-GQDs show good selectivity for Mg2+, Sr2+, and Ba2+, respectively. Finally, we also show the successful detection of Ca2+ in vitro based on C-GQDs.