First Principle Evaluation of Photocatalytic Suitability for TiO2-Based Nanotubes

Water splitting under the influence of solar light on semiconducting electrodes Immersed in aqueous electrolyte is a potentially clean and renewable source for hydrogen fuel production. Its efficiency depends on relative position of the band gap edges (the visible light interval between infrared and ultraviolet (UV) ranges of electromagnetic spectrum corresponds to gap widths 1.5–2.8 eV) accompanied by a proper band alignment relative to both reduction (H+/H2) and oxidation (O2/H2O) potentials (−4.44 eV and −5.67 eV on energy scale for vacuum, respectively) which must be positioned inside the band gap. Its width for TiO2 anatase-structured bulk is experimentally found to be 3.2 eV, which corresponds to photocatalytic activity under UV light possessing only ~1% efficiency of sunlight energy conversion. Noticeable growth of this efficiency can be achieved by by adjusting the band gap edges for titania bulk through nanoscale transformation of its morphology to anatase-type nanotubes (NTs) (formed by folding of (001) or (101) nanothin TiO2 sheets consisting of 9 or 6 atomic layers and possessing either (n,0) or (−n,n) chiralities, respectively) accompanied by partial substitution of pristine atoms by CO, FeTi, NO and SO single dopants as well as NO+SO codopants. In the latter case, the band gap can be reduced down to 2.2 eV while the efficiency is achieved up to ~15%. The energy differences between the edges of band gap (VB and CB), the highest occupied and lowest unoccupied impurity levels inside the band gap (HOIL and LUIL, respectively) induced in doped NTs, while preserving the proper disposition of these levels relatively to the redox potentials, so that εVB<εHOIL<εO2/H2O<εH+/H2<εLUIL<εCB, thus reducing the photon energy required for dissociation of H2O molecule. In this chapter, we analyze applicability of large-scale first principle calculations on the doped single-wall titania NTs of different morphologies with the aim of establishment of their suitability for photocatalytic water splitting

Use of site symmetry in supercell models of defective crystals: Polarons in CeO2

The authors thank R. Merkle and G. W. Watson for stimulating discussions. E. K. also acknowledges partial financial support from the Russian Science Foundation for the study of charged defects under the project 14-43-00052. A. C. also acknowledges financial support from the University of Latvia Foundation (Arnis Riekstins's "MikroTik" donation). E. K. and D. G. express their gratitude to the High Performance Computer Centre in Stuttgart (HLRS, project DEFTD 12939) for the provided computer facilities whereas R. A. E. thanks the St. Petersburg State University Computer Center for assistance in high-performance calculations.In supercell calculations of defective crystals, it is common to place a point defect or vacancy in the atomic position with the highest possible point symmetry. Then, the initial atomic structure is often arbitrary distorted before its optimization, which searches for the total energy minimum. In this paper, we suggest an alternative approach to the application of supercell models and show that it is necessary to preliminarily analyze the site symmetry of the split Wyckoff positions of the perfect crystal supercell atoms (which will be substituted or removed in defective crystals) and then perform supercell calculations with point defects for different possible site symmetries, to find the energetically most favorable defect configuration, which does not necessarily correspond to the highest site symmetry. Using CeO2 as an example, it is demonstrated that this use of the site symmetry of the removed oxygen atoms in the supercells with vacancies allows us to obtain all the possible atomic and magnetic polaron configurations, and predict which vacancy positions correspond to the lowest formation energies associated with small polarons. We give a simple symmetry based explanation for the existence of controversies in the literature on the nature of the oxygen vacancies in CeO2. In particular, the experimentally observed small polaron formation could arise for oxygen vacancies with the lowest Cs site symmetry, which exist in 3 x 3 x 3 and larger supercells. The results of first principles calculations using a linear combination of atomic orbitals and hybrid exchange-correlation functionals are compared with those from previous studies, obtained using a widely used DFT+U approach.Russian Science Foundation 14-43-00052; Saint Petersburg State University; University of Latvia Foundation (Arnis Riekstins's "MikroTik" donation); Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

New and rare lichens and allied fungi from Arkhangelsk region, North-West Russia

Thirty-one lichen-forming fungi, 12 lichenicolous fungi, and 5 non-lichenized fungi are reported as new for Arkhangelsk Region; 7 species are new for its mainland area. Micarea fallax is reported for the first time for Russia; M. laeta and M. pusilla are new for the European part of Russia. The second finding of Nicropuncta rugulosa for Russia is recorded; microconidia are first observed in this species. The records of ten species which have been included in the new edition of the Red Data Book of the Arkhangelsk Region (2020) are presented. Nephromopsis laureri from the Red Data Book of the Russian Federation (2008) and Leptogium rivulare from the IUCN Red List are reported for the first time for Arkhangelsk Region

Antiviral susceptibility of clade 2.3.4.4b highly pathogenic avian influenza A(H5N1) viruses isolated from birds and mammals in the United States, 2022

Clade 2.3.4.4b highly pathogenic avian influenza (HPAI) A(H5N1) viruses that are responsible for devastating outbreaks in birds and mammals pose a potential threat to public health. Here, we evaluated their susceptibility to influenza antivirals. Of 1,015 sequences of HPAI A(H5N1) viruses collected in the United States during 2022, eight viruses (∼0.8%) had a molecular marker of drug resistance to an FDA-approved antiviral: three adamantane-resistant (M2-V27A), four oseltamivir-resistant (NA-H275Y), and one baloxavir-resistant (PA-I38T). Additionally, 31 viruses contained mutations that may reduce susceptibility to inhibitors of neuraminidase (NA) (n = 20) or cap-dependent endonuclease (CEN) (n = 11). A panel of 22 representative viruses was tested phenotypically. Overall, clade 2.3.4.4b A(H5N1) viruses lacking recognized resistance mutations were susceptible to FDA-approved antivirals. Oseltamivir was least potent at inhibiting NA activity, while the investigational NA inhibitor AV5080 was most potent, including against NA mutants. A novel NA substitution T438N conferred 12-fold reduced inhibition by zanamivir, and in combination with the known marker N295S, synergistically affected susceptibility to all five NA inhibitors. In cell culture-based assays HINT and IRINA, the PA-I38T virus displayed 75- to 108-fold and 37- to 78-fold reduced susceptibility to CEN inhibitors, baloxavir and the investigational AV5116, respectively. Viruses with PA-I38M or PA-A37T showed 5- to 10-fold reduced susceptibilities. As HPAI A(H5N1) viruses continue to circulate and evolve, close monitoring of drug susceptibility is needed for risk assessment and to inform decisions regarding antiviral stockpiling

Proton migration barriers in BaFeO3-δ – insights from DFT calculations

A. C. and D. G. thank the Latvian Council of Science (project no. lzp-2021/1-0203) for financial support. Christina Ertural (RWTH Aachen) is thanked for assistance with LOBSTER technical questions. Yuri Mastrikov (University of Latvia) is thanked for discussions of technical details in NEB calculations at initial stages of present study. Calculations were performed at the HLRS, University of Stuttgart, within the project 12939 DEFTD. The Institute of Solid State Physics, University of Latvia, as the Centre of Excellence has received funding from the European Union's Horizon 2020 Frame-work Programme H2020-WIDESPREAD-01-2016–2017-Teaming Phase2 under grant agreement No. 739508, Project CAMART2. Open Access funding provided by the Max Planck Society.Latvian Council of Science (project no. lzp-2021/1-0203); project 12939 DEFTD; The Institute of Solid State Physics, University of Latvia, as the Centre of Excellence has received funding from the European Union's Horizon 2020 Frame-work Programme H2020-WIDESPREAD-01-2016–2017-Teaming Phase2 under grant agreement No. 739508, Project CAMART2

FOXM1-AKT Positive Regulation Loop Provides Venetoclax Resistance in AML

Forkhead box protein M1 (FOXM1) is a crucial regulator of cancer development and chemoresistance. It is often overexpressed in acute myeloid leukemia (AML) and is associated with poor survival and reduced efficacy of cytarabine therapy. Molecular mechanisms underlying high FOXM1 expression levels in malignant cells are still unclear. Here we demonstrate that AKT and FOXM1 constitute a positive autoregulatory loop in AML cells that sustains high activity of both pro-oncogenic regulators. Inactivation of either AKT or FOXM1 signaling results in disruption of whole loop, coordinated suppression of FOXM1 or AKT, respectively, and similar transcriptomic changes. AML cells with inhibited AKT activity or stable FOXM1 knockdown display increase i

The local atomic structure and thermoelectric properties of Irdoped ZnO: hybrid DFT calculations and XAS experiments

We greatly acknowledge the financial support via the ERAF Project No. 1.1.1.1/18/A/073. Calculations have been performed under the Project HPC-EUROPA3 (INFRAIA-2016-1-730897), with the support of the EC Research Innovation Action under the H2020 Programme. A. C. gratefully acknowledges the technical support received from KTH-PDC. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2We combined the hybrid density functional theory (DFT) calculations and X-ray absorption spectroscopy (XAS) experiments in the study of the local atomic structure around Ir ions in ZnO thin films with different iridium content. This was then used in the first principles analysis of the thermoelectric properties of material. The emphasis has been put on the conditions for a positive Seebeck coefficient and p-type electrical conductivity as the functions of the Fermi level. We studied both computationally and experimentally several possible IrOx polyhedra (complexes) with a different number of surrounding oxygens and Ir oxidation states, including those with the formation of peroxide ions (O22−). In particular, octahedral coordination of iridium ions was identified by reverse Monte Carlo (RMC) simulations of the Ir L3-edge EXAFS spectra of ZnO:Ir thin films as the predominant complex, which is supported by the calculated lowest interstitial oxygen incorporation energies. All the calculated IrOx (x = 4, 5, 6) complexes, regardless of Ir the oxidation state, demonstrate potential for p-type conduction if the Fermi level (μF) falls in the range of 0–0.8 eV from the valence band maximum (VBM) and the Ir concentration is high enough (12.5% in the present DFT calculations). Even though the corresponding calculated Seebeck coefficient (S) around 80–89 μV K−1 slightly exceeds the experimental values, we emphasise the presence of an important plateau in the dependence of S on μF in this range for two complexes with the formation of peroxide ions (O22−). We predicted also that peroxide ions O22− are characterized by the calculated phonon frequencies of 810–942 cm−1 in agreement with our previous Raman experimental results. In this light, we discuss the high sensitivity of calculated S(μF) dependences to the atomic and electronic structure.--//--This is the preprint version of the following article: Andrei Chesnokov, Denis Gryaznov, Natalia V. Skorodumova, Eugene A. Kotomin, Andrea Zitolo, Martins Zubkins, Alexei Kuzmin, Andris Anspoks, Juris Purans; The local atomic structure and thermoelectric properties of Ir-doped ZnO: hybrid DFT calculations and XAS experiment, Journal of Materials CHemistry C: Volume 14, 2021, which has been published in final form at https://pubs.rsc.org/en/content/articlelanding/2021/tc/d1tc00223f#!divAbstract This article may be used for non-commercial purposes in accordance with Royal Society of Chemistry Terms and Conditions for Sharing and Self-Archiving.ERAF Project No. 1.1.1.1/18/A/073; Project HPC-EUROPA3 (INFRAIA-2016-1-730897) under EC Research Innovation Action under H2020; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Исследование влияния природы твердых кислотных катализаторов на их активность в гидролизе сахарозы и целлюлозы

Activity of solid acid catalysts (based on SBA-15 and carbon Sibunit) in hydrolysis of sucrose at 80 °C and of microcrystalline cellulose (MCC) at 150 °C was compared. The maximal activity in sucrose hydrolysis (rate constant 9,2·10-4 s-1 ) was observed for SBA-15 containing anchored SO3H-groups. All studied catalysts increase the conversion of MCC in the following order (for hydrolysis time 12 h): without catalyst (4,2 % wt.) < Sibunit (16-19 % wt.) < acid Nafion® (21,5 % wt.) < SBA-15 (80,1 % wt.). Products of MCC hydrolysis contain along with glucose the oligosaccharides and impurities of mannose and xyloseСопоставлена активность твердых кислотных катализаторов на основе SBA-15 и Сибунита в гидролизе сахарозы при 80 °С и микрокристаллической целлюлозы (МКЦ) при 150 °С. Максимальная активность в реакции гидролиза сахарозы наблюдалась у SBA-15 (константа скорости 9,2·10-4с-1), содержащего закрепленные SO3H-группы. Для всех изученных катализаторов конверсия МКЦ за время гидролиза 12 ч увеличивается в следующем порядке: без катализатора (4,2 % мас.) < Сибунит (16-19 % мас.) < Nafion® (21,5 % мас.) < SBA-15 (80,1 % мас.). Установлено, что продукты гидролиза MКЦ содержат наряду с глюкозой олигосахариды и примеси маннозы и ксилоз