Publications by authors named "Olga Nazarenko"

22 Publications

  • Page 1 of 1

Comparison of Heavy Metal Content in in Various Impact Zones.

ACS Omega 2020 Sep 3;5(36):23393-23400. Epub 2020 Sep 3.

Research Institute of Obstetrics and Pediatrics, Rostov-on-Don 344012, Russia.

A study on of two anthropogenically heavy metal-polluted impact zones of the Rostov region, namely Lake Atamanskoye and Novocherkasskaya Power Station, was conducted. The influence of soil pollution on the Pb, Zn, and Cu accumulation in various organs of , which is widespread in the studied territories, was established. An extremely high level of Zn content (3051 mg/kg) was observed in the soils of the impact zone of Lake Atamanskoe, as well as an excess over the maximum permissible level for Pb and Cu (32 and 132 mg/kg accordingly). The distribution coefficient (DC) of heavy metal translocation showed the highest mobility of Zn (DC ≥ 1 in 9 out of 11 sites) and the smallest of Pb (DC ≥ 1 in 4 out of 11 sites) in plants of the Novocherkasskaya Power Station impact zone. The zone of increased pollution around Lake Atamanskoye was 1.5 km, which was much smaller than the Novocherkasskaya Power Station zone of high pollution (5 km). However, vehicle emissions accumulated in the soil over the past decades had a greater effect on the Pb translocation than atmospheric emissions of the enterprise.
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http://dx.doi.org/10.1021/acsomega.0c03340DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496012PMC
September 2020

Environmental and human health risk assessment of potentially toxic elements in soils around the largest coal-fired power station in Southern Russia.

Environ Geochem Health 2020 Jul 17. Epub 2020 Jul 17.

Southern Federal University, 194/1 Stachki ave., Rostov-on-Don, Russian Federation.

The combustion of solid fuel at power plants pollutes adjacent areas with potentially toxic elements (PTEs), which increases risks to public health in the vicinity of these facilities. The proposed paper presents the results of a geochemical study of PTEs (Cr, Mn, Ni, Cu, Zn, Cd, and Pb) contamination in the vicinity of Novocherkassk Power Plant (NPP) as it relates to environmental and human health risks. The impact zone of NPP is pronounced for a distance of approximately 7 km northwest of the enterprise-the second largest coal power plant in Southern Russia. Data from monitoring sites lead us to conclude that spatial patterns of soil pollution are strongly influenced by the peculiarities of local atmospheric circulation, while the characteristics of soils within the study area play a secondary role. The highest levels of PTEs and their exchangeable forms exceed both regional background and sanitary and hygienic standards within a radius of 3 km to the west of the plant, which corresponds to a zone of soils contaminated with Cr, Ni, Cu, Zn, Cd, and Pb. The carcinogenic risk to human health slightly exceeds the permissible standard of 1 × 10 for soils in close vicinity of the enterprise due to the potential human intake of Ni, Cd, and Pb. The results of the health risk assessment indicate no noncarcinogenic risks for adults, while for children, they are low.
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http://dx.doi.org/10.1007/s10653-020-00666-4DOI Listing
July 2020

Lead-Halide Scalar Couplings in Pb NMR of APbX Perovskites (A = Cs, Methylammonium, Formamidinium; X = Cl, Br, I).

Sci Rep 2020 May 19;10(1):8229. Epub 2020 May 19.

Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, CH-8093, Switzerland.

Understanding the structure and dynamics of newcomer optoelectronic materials - lead halide perovskites APbX [A = Cs, methylammonium (CHNH, MA), formamidinium (CH(NH), FA); X = Cl, Br, I] - has been a major research thrust. In this work, new insights could be gained by using Pb solid-state nuclear magnetic resonance (NMR) spectroscopy at variable temperatures between 100 and 300 K. The existence of scalar couplings J of ca. 400 Hz and J of ca. 2.3 kHz could be confirmed for MAPbX and CsPbX. Diverse and fast structure dynamics, including rotations of A-cations, harmonic and anharmonic vibrations of the lead-halide framework and ionic mobility, affect the resolution of the coupling pattern. Pb NMR can therefore be used to detect the structural disorder and phase transitions. Furthermore, by comparing bulk and nanocrystalline CsPbBr a greater structural disorder of the PbBr-octahedra had been confirmed in a nanoscale counterpart, not readily captured by diffraction-based techniques.
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http://dx.doi.org/10.1038/s41598-020-65071-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7237655PMC
May 2020

Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy.

Phys Chem Chem Phys 2020 Mar;22(10):5604-5614

Institute of Solid State Physics, Technische Universitat Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.

Lead halide perovskite semiconductors providing record efficiencies of solar cells have usually mixed compositions doped in A- and X-sites to enhance the phase stability. The cubic form of formamidinium (FA) lead iodide reveals excellent opto-electronic properties but transforms at room temperature (RT) into a hexagonal structure which does not effectively absorb visible light. This metastable form and the mechanism of its stabilization by Cs+ and Br- incorporation are poorly characterized and insufficiently understood. We report here the vibrational properties of cubic FAPbI3 investigated by DFT calculations on phonon frequencies and intensities, and micro-Raman spectroscopy. The effects of Cs+ and Br- partial substitution are discussed. We support our results with the study of FAPbBr3 which expands the identification of vibrational modes to the previously unpublished low frequency region (<500 cm-1). Our results show that the incorporation of Cs+ and Br- leads to the coupling of the displacement of the A-site components and weakens the bonds between FA+ and the PbX6 octahedra. We suggest that the enhancement of α-FAPbI3 stability can be a product of the release of tensile stresses in the Pb-X bond, which is reflected in a red-shift of the low frequency region of the Raman spectrum (<200 cm-1).
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http://dx.doi.org/10.1039/c9cp06568gDOI Listing
March 2020

Accumulation and transformation of benzo[a]pyrene in Haplic Chernozem under artificial contamination.

Environ Geochem Health 2020 Aug 1;42(8):2485-2494. Epub 2019 Jul 1.

The Federal State Budgetary Establishment, The State Center of Agrochemical Service 'Rostovsky', Rostov Region, Russian Federation.

Polycyclic aromatic hydrocarbons (PAHs) have been a major concern because of their carcinogenicity, mutagenicity, teratogenicity and wide distribution in the environment. Over 90% of PAHs in the environment exist on soil surface/sediment. Benzo[a]pyrene (BaP) is one of the predominant PAHs in soil. Thus, it is critically important to understand the patterns of BaP accumulation and transformation peculiarities in soil for the risk assessment. The studies were conducted in model experiment with Haplic Chernozem spiked with various doses of BaP (20, 200, 400 and 800 µg kg) equivalent to 1, 10, 20 and 40 levels of maximum permissible concentrations. The unique properties of Haplic Chernozem were studied allow to accumulate and transform BaP as well as barley plants ability to absorb of some BaP concentration. Extraction of BaP from the soil was carried out by the saponification method. The qualitative and quantitative determination of BaP and other polycyclic aromatic hydrocarbons (PAHs) was performed by high-performance liquid chromatography with fluorescence detection (Agilent 1260 Germany, 2014). BaP accumulation in soil depended on the applied BaP concentrations in Haplic Chernozem. Studying the features of PAHs transformation in the soil of a model experiment 1 year after the compound application showed the BaP content in the soil decreased up to 11-40%. Two years after the BaP application the content in the soil decreased up to 15-44% from the initial BaP content in the soil. The percentage of BaP concentration reduction in Haplic Chernozem increased with an increase in the dose of the applied xenobiotic. An increase in the dose of the applied pollutant to the soil of the model experiment contributed to an increase in all PAHs, which indicated a rapid BaP transformation in Haplic Chernozem. The PAHs content in the soils of model experiment in the first year of the research formed the following descending series: pyrene > chrysene > fluoranthene > phenanthrene. In the second year of research the phenanthrene content became higher than the fluoranthene content. The content of these compounds exceeded 20% of the total PAHs content in the soil samples in the first and second years of the model experiment. The features of PAHs accumulation and transformation in soils under artificial pollution showed the degradation of large-nuclear PAHs, starting from 5-ring polyarenes, and their structural reorganization into the less-nuclear polyarenes, such as 4-, 3-, and 2-ring PAHs. During the 2 years of the model experiment the BaP concentration in the soil decreased up to 15-44% from the initial BaP content in the soil.
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http://dx.doi.org/10.1007/s10653-019-00362-yDOI Listing
August 2020

High-resolution remote thermometry and thermography using luminescent low-dimensional tin-halide perovskites.

Nat Mater 2019 Aug 1;18(8):846-852. Epub 2019 Jul 1.

Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.

Although metal-halide perovskites have recently revolutionized research in optoelectronics through a unique combination of performance and synthetic simplicity, their low-dimensional counterparts can further expand the field with hitherto unknown and practically useful optical functionalities. In this context, we present the strong temperature dependence of the photoluminescence lifetime of low-dimensional, perovskite-like tin-halides and apply this property to thermal imaging. The photoluminescence lifetimes are governed by the heat-assisted de-trapping of self-trapped excitons, and their values can be varied over several orders of magnitude by adjusting the temperature (up to 20 ns °C). Typically, this sensitive range spans up to 100 °C, and it is both compound-specific and shown to be compositionally and structurally tunable from -100 to 110 °C going from [C(NH)]SnBr to CsSnBr and (CNHI)SnI. Finally, through the implementation of cost-effective hardware for fluorescence lifetime imaging, based on time-of-flight technology, these thermoluminophores have been used to record thermographic videos with high spatial and thermal resolution.
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http://dx.doi.org/10.1038/s41563-019-0416-2DOI Listing
August 2019

Tuning Transport Properties in Thermoelectric Nanocomposites through Inorganic Ligands and Heterostructured Building Blocks.

ACS Nano 2019 Jun 14;13(6):6572-6580. Epub 2019 Jun 14.

Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1 , Zürich CH-8093 , Switzerland.

Methodologies that involve the use of nanoparticles as "artificial atoms" to rationally build materials in a bottom-up fashion are particularly well-suited to control the matter at the nanoscale. Colloidal synthetic routes allow for an exquisite control over such "artificial atoms" in terms of size, shape, and crystal phase as well as core and surface compositions. We present here a bottom-up approach to produce Pb-Ag-K-S-Te nanocomposites, which is a highly promising system for thermoelectric energy conversion. First, we developed a high-yield and scalable colloidal synthesis route to uniform lead sulfide (PbS) nanorods, whose tips are made of silver sulfide (AgS). We then took advantage of the large surface-to-volume ratio to introduce a p-type dopant (K) by replacing native organic ligands with KTe. Upon thermal consolidation, KTe-surface modified PbS-AgS nanorods yield p-type doped nanocomposites with PbTe and PbS as major phases and AgS and AgTe as embedded nanoinclusions. Thermoelectric characterization of such consolidated nanosolids showed a high thermoelectric figure-of-merit of 1 at 620 K.
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http://dx.doi.org/10.1021/acsnano.9b00346DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6595432PMC
June 2019

Guanidinium and Mixed Cesium-Guanidinium Tin(II) Bromides: Effects of Quantum Confinement and Out-of-Plane Octahedral Tilting.

Chem Mater 2019 Mar 13;31(6):2121-2129. Epub 2019 Feb 13.

Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1, CH-8093 Zürich, Switzerland.

Hybrid organic-inorganic main-group metal halide compounds are the subject of intense research owing to their unique optoelectronic characteristics. In this work, we report the synthesis, structure, and electronic and optical properties of a family of hybrid tin (II) bromide compounds comprising guanidinium [G, C(NH)] and mixed cesium-guanidinium cations: GSnBr, CsGSnBr, and CsGSnBr. GSnBr has a one-dimensional structure that consists of chains of corner-sharing [SnBr] square pyramids and G cations situated in between the chains. Cs exhibits a pronounced structure-directing effect where a mixture of Cs and G cations forms mono- and bilayered two-dimensional perovskites: CsGSnBr and CsGSnBr. Furthermore, the flat shapes of the guanidinium cations induce anisotropic out-of-plane tilts of the [SnBr] octahedra in the CsGSnBr and CsGSnBr compounds. In GSnBr, the Sn lone pair is highly stereoactive and favors non-octahedral, that is, square pyramidal coordination of Sn(II). GSnBr exhibits bright broad-band emission from self-trapped excitonic states, owing to its soft lattice and electronic localization. This emission in GSnBr is characterized by a photoluminescence (PL) quantum yield of 2% at room temperature (RT; 75 ± 5% at 77 K) and a fast PL lifetime of 18 ns at room temperature.
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http://dx.doi.org/10.1021/acs.chemmater.9b00038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6438322PMC
March 2019

Environmental pollution of soil with PAHs in energy producing plants zone.

Sci Total Environ 2019 Mar 7;655:232-241. Epub 2018 Nov 7.

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed environmental toxicants primarily formed during the incomplete combustion of organic materials (for example, coal, oil, gasoline and wood). Power energy plants are the main sources of organic contaminants including PAHs. The purpose of the present research was to study the Novocherkassk Electric Power Station (NEPS) emission effects of PAHs accumulation in soils. The regional levels, types (groups) and spatial distribution of 16 priority PAHs were investigated. The monitoring sites were located on fallow lands of the 20 km around NEPS. PAHs extraction from collected soil samples was performed using the ecologically clean express-method of subcritical water extraction. The total PAHs content gradually increased in soil of the studied territories during 2016-2017 due to an increase in contaminants emission. Accordingly 16 priority PAHs were determined in the soil samples collected from the sites located to the northwest from NEPS in direction of predominant winds. The 5-km zone situated in direction of predominant winds was highly subjected to PAHs contamination, with maximal accumulation at a distance of 1.6 km from the source. The ratio of high- and low-molecular weight PAHs content in soils of monitoring sites was taken as an index of environmental soil contamination. The high-molecular weight PAHs concentration prevailed in monitoring sites soils situated in direction of predominant winds from NEPS, while the concentration of low-molecular weight PAHs prevailed in the monitoring sites soils situated around NEPS. Soil properties also influenced PAHs accumulation. Polyarenes content in Haplic Chernozems and Haplic Chernozems (Stagnic) was higher versus Fluvisols. This study provides the understanding and model the fate of PAHs in regional technogenic landscape.
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http://dx.doi.org/10.1016/j.scitotenv.2018.11.080DOI Listing
March 2019

Highly Emissive Self-Trapped Excitons in Fully Inorganic Zero-Dimensional Tin Halides.

Angew Chem Int Ed Engl 2018 Aug 30;57(35):11329-11333. Epub 2018 Jul 30.

Laboratory of Inorganic Chemistry, ETH Zürich, CH-8093, Zürich, Switzerland.

The spatial localization of charge carriers to promote the formation of bound excitons and concomitantly enhance radiative recombination has long been a goal for luminescent semiconductors. Zero-dimensional materials structurally impose carrier localization and result in the formation of localized Frenkel excitons. Now the fully inorganic, perovskite-derived zero-dimensional Sn material Cs SnBr is presented that exhibits room-temperature broad-band photoluminescence centered at 540 nm with a quantum yield (QY) of 15±5 %. A series of analogous compositions following the general formula Cs A Sn(Br I ) (A=Rb, K; x≤1, y≤1) can be prepared. The emission of these materials ranges from 500 nm to 620 nm with the possibility to compositionally tune the Stokes shift and the self-trapped exciton emission bands.
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http://dx.doi.org/10.1002/anie.201806452DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6175341PMC
August 2018

Low-Cost Synthesis of Highly Luminescent Colloidal Lead Halide Perovskite Nanocrystals by Wet Ball Milling.

ACS Appl Nano Mater 2018 Mar 5;1(3):1300-1308. Epub 2018 Mar 5.

Institute of Inorganic Chemistry, Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland.

Lead halide perovskites of APbX type [A = Cs, formamidinium (FA), methylammonium; X = Br, I] in the form of ligand-capped colloidal nanocrystals (NCs) are widely studied as versatile photonic sources. FAPbBr and CsPbBr NCs have become promising as spectrally narrow green primary emitters in backlighting of liquid-crystal displays (peak at 520-530 nm, full width at half-maximum of 22-30 nm). Herein, we report that wet ball milling of bulk APbBr (A = Cs, FA) mixed with solvents and capping ligands yields green luminescent colloidal NCs with a high overall reaction yield and optoelectronic quality on par with that of NCs of the same composition obtained by hot-injection method. We emphasize the superiority of oleylammonium bromide as a capping ligand used for this procedure over the standard oleic acid and oleylamine. We also show a mechanically induced anion-exchange reaction for the formation of orange-emissive CsPb(Br/I) NCs.
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http://dx.doi.org/10.1021/acsanm.8b00038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5999230PMC
March 2018

Optogenetic regulation of transcription.

BMC Neurosci 2018 04 19;19(Suppl 1):12. Epub 2018 Apr 19.

Localized Therapeutics, LLC, San Diego, CA, USA.

Optogenetics has become widely recognized for its success in real-time control of brain neurons by utilizing non-mammalian photosensitive proteins to open or close membrane channels. Here we review a less well known type of optogenetic constructs that employs photosensitive proteins to transduce the signal to regulate gene transcription, and its possible use in medicine. One of the problems with existing gene therapies is that they could remain active indefinitely while not allowing regulated transgene production on demand. Optogenetic regulation of transcription (ORT) could potentially be used to regulate the production of a biological drug in situ, by repeatedly applying light to the tissue, and inducing expression of therapeutic transgenes when needed. Red and near infrared wavelengths, which are capable of penetration into tissues, have potential for therapeutic applications. Existing ORT systems are reviewed herein with these considerations in mind.
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http://dx.doi.org/10.1186/s12868-018-0411-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5998900PMC
April 2018

The role of Alu-derived RNAs in Alzheimer's and other neurodegenerative conditions.

Med Hypotheses 2018 Jun 21;115:29-34. Epub 2018 Mar 21.

Biophysics Research Institute, San Diego, CA, USA; Vaccine Research Institute of San Diego, San Diego, CA, USA; Localized Therapeutics, LLC, San Diego, CA, USA. Electronic address:

Non-coding RNAs have emerged as essential contributors to neuroinflammation. The Alu element is the most abundant potential source of non-coding RNA in the human genome represented by over 1.1 million copies totaling ∼10% of the genome's mass. Accumulation of "Alu RNA" was observed in the brains of individuals with dementia and Creutzfeldt-Jakob disease - a degenerative brain disorder. "Alu RNAs" activate inflammatory pathways and apoptosis in the non-neural cells. In particular, the "Alu RNA" cytotoxicity is suggested as a mechanism in retinal pigment epithelium (RPE), a compartment damaged in the process of age-related macular degeneration. In RPE cells, the deficiency of Dicer is reported to lead to an accumulation of P3Alu transcripts, subsequent activation of the ERK1/2 signaling pathway, and the formation of NLRP3 inflammasome. In turn, these events result in RPE cell death by apoptosis. Importantly, RPE cells are of neuroectodermal origin, these cells display more similarity to neurons than to other epithelial cells. Thus, it is plausible that the mechanisms of "Alu RNA" cytotoxicity in brain neurons are similar to that in RPE. We hypothesize that accumulation of polymerase III-transcribed noncoding RNA of Alu (P3Alu) may contribute to both neuroinflammation and neurodegeneration associated with Alzheimer's disease (AD) and other degenerative brain disorders. This hypothesis points toward a novel molecular pathway not previously considered for the treatment of AD.
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http://dx.doi.org/10.1016/j.mehy.2018.03.008DOI Listing
June 2018

Colloidal CsPbX (X = Cl, Br, I) Nanocrystals 2.0: Zwitterionic Capping Ligands for Improved Durability and Stability.

ACS Energy Lett 2018 Mar 9;3(3):641-646. Epub 2018 Feb 9.

Institute of Inorganic Chemistry, Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland.

Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as versatile photonic sources. Their processing and optoelectronic applications are hampered by the loss of colloidal stability and structural integrity due to the facile desorption of surface capping molecules during isolation and purification. To address this issue, herein, we propose a new ligand capping strategy utilizing common and inexpensive long-chain zwitterionic molecules such as 3-(,-dimethyloctadecylammonio)propanesulfonate, resulting in much improved chemical durability. In particular, this class of ligands allows for the isolation of clean NCs with high photoluminescence quantum yields (PL QYs) of above 90% after four rounds of precipitation/redispersion along with much higher overall reaction yields of uniform and colloidal dispersible NCs. Densely packed films of these NCs exhibit high PL QY values and effective charge transport. Consequently, they exhibit photoconductivity and low thresholds for amplified spontaneous emission of 2 μJ cm under femtosecond optical excitation and are suited for efficient light-emitting diodes.
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http://dx.doi.org/10.1021/acsenergylett.8b00035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5848145PMC
March 2018

Guanidinium-Formamidinium Lead Iodide: A Layered Perovskite-Related Compound with Red Luminescence at Room Temperature.

J Am Chem Soc 2018 03 12;140(11):3850-3853. Epub 2018 Mar 12.

Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Bioscience , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland.

Two-dimensional hybrid organic-inorganic lead halides perovskite-type compounds have attracted immense scientific interest due to their remarkable optoelectronic properties and tailorable crystal structures. In this work, we present a new layered hybrid lead halide, namely [CH(NH)][C(NH)]PbI, wherein puckered lead-iodide layers are separated by two small and stable organic cations: formamidinium, CH(NH), and guanidinium, C(NH). This perovskite is thermally stable up to 255 °C, exhibits room-temperature photoluminescence in the red region with a quantum yield of 3.5%, and is photoconductive. This study highlights a vast structural diversity that exists in the compositional space typically used in perovskite photovoltaics.
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http://dx.doi.org/10.1021/jacs.8b00194DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5867663PMC
March 2018

Tuning -Type Transport in Bottom-Up-Engineered Nanocrystalline Pb Chalcogenides Using Alkali Metal Chalcogenides as Capping Ligands.

Chem Mater 2017 Sep 23;29(17):7093-7097. Epub 2017 Aug 23.

Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, Zürich CH-8093, Switzerland.

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http://dx.doi.org/10.1021/acs.chemmater.7b02967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5805404PMC
September 2017

On possible role of DNA electrodynamics in chromatin regulation.

Prog Biophys Mol Biol 2018 05 30;134:50-54. Epub 2017 Dec 30.

Localized Therapeutics LLC, San Diego, CA, USA; Vaccine Research Institute of San Diego, San Diego, CA, USA; Biophysics Research Institute, San Diego, CA, USA. Electronic address:

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http://dx.doi.org/10.1016/j.pbiomolbio.2017.12.006DOI Listing
May 2018

Luminescent and Photoconductive Layered Lead Halide Perovskite Compounds Comprising Mixtures of Cesium and Guanidinium Cations.

Inorg Chem 2017 Oct 12;56(19):11552-11564. Epub 2017 Sep 12.

ETH Zürich , Department of Chemistry and Applied Biosciences, CH-8093 Zurich, Switzerland.

Interest in hybrid organic-inorganic lead halide compounds with perovskite-like two-dimensional crystal structures is growing due to the unique electronic and optoelectronic properties of these compounds. Herein, we demonstrate the synthesis, thermal and optical properties, and calculations of the electronic band structures for one- and two-layer compounds comprising both cesium and guanidinium cations: Cs[C(NH)]PbI (I), Cs[C(NH)]PbBr (II), and Cs[C(NH)]PbBr (III). Compounds I and II exhibit intense photoluminescence at low temperatures, whereas compound III is emissive at room temperature. All of the obtained substances are stable in air and do not thermally decompose until 300 °C. Since Cs and C(NH) are increasingly utilized in precursor solutions for depositing polycrystalline lead halide perovskite thin films for photovoltaics, exploring possible compounds within this compositional space is of high practical relevance to understanding the photophysics and atomistic chemical nature of such films.
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http://dx.doi.org/10.1021/acs.inorgchem.7b01204DOI Listing
October 2017

Cobalt(II) and cadmium(II) square grids supported with 4,4'-bipyrazole and accommodating 3-carboxyadamantane-1-carboxylate.

Acta Crystallogr C 2013 Mar 9;69(Pt 3):232-6. Epub 2013 Feb 9.

Inorganic Chemistry Department, Taras Shevchenko National University of Kyiv, Volodymyrska Street 64/13, Kyiv 01601, Ukraine.

In poly[[bis(μ-4,4'-bi-1H-pyrazole-κ(2)N(2):N(2'))bis(3-carboxyadamantane-1-carboxylato-κO(1))cobalt(II)] dihydrate], {[Co(C12H15O4)2(C6H6N4)2]·2H2O}n, (I), the Co(2+) cation lies on an inversion centre and the 4,4'-bipyrazole (4,4'-bpz) ligands are also situated across centres of inversion. In its non-isomorphous cadmium analogue, {[Cd(C12H15O4)2(C6H6N4)2]·2H2O}n, (II), the Cd(2+) cation lies on a twofold axis. In both compounds, the metal cations adopt an octahedral coordination, with four pyrazole N atoms in the equatorial plane [Co-N = 2.156 (2) and 2.162 (2) Å; Cd-N = 2.298 (2) and 2.321 (2) Å] and two axial carboxylate O atoms [Co-O = 2.1547 (18) Å and Cd-O = 2.347 (2) Å]. In both structures, interligand hydrogen bonding [N...O = 2.682 (3)-2.819 (3) Å] is essential for stabilization of the MN4O2 environment with its unusually high (for bulky adamantanecarboxylates) number of coordinated N-donor co-ligands. The compounds adopt two-dimensional coordination connectivities and exist as square-grid [M(4,4'-bpz)2]n networks accommodating monodentate carboxylate ligands. The interlayer linkage is provided by hydrogen bonds from the carboxylic acid groups via the solvent water molecules [O...O = 2.565 (3) and 2.616 (3) Å] to the carboxylate groups in the next layer [O...O = 2.717 (3)-2.841 (3) Å], thereby extending the structures in the third dimension.
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http://dx.doi.org/10.1107/S0108270113003405DOI Listing
March 2013

Synthesis and characterization of metal carbides nanoparticles produced by electrical explosion of wires.

J Nanosci Nanotechnol 2012 Oct;12(10):8137-42

Department of General and Inorganic Chemistry, Institute of High-Technology Physics, Tomsk Polytechnic University, Tomsk, Lenin str 30, 634050, Russia.

Tungsten, titanium, tantalum, aluminum carbides nanoparticles were produced by electrical explosion of wires. The explosions were carried out in gaseous mixtures of argon and acetylene at different ratios, argon and propane, and in liquids such as benzene, toluene, decane. The effects of the synthesis conditions on the size and phase composition of metal carbide nanoparticles were investigated. The thermal activity of the prepared powders was studied by the method of differential thermal analysis at the heating in air. Thermodynamic analysis of carbides formation during the process of electrical explosion has been made. The output of the chemical compounds depends on their thermal stability: the more thermally stable they are, the higher their output.
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http://dx.doi.org/10.1166/jnn.2012.4515DOI Listing
October 2012

The high frequency of HIV type 1-specific cellular immune responses in seronegative individuals with parenteral and/or heterosexual HIV type 1 exposure.

AIDS Res Hum Retroviruses 2012 Dec 26;28(12):1598-605. Epub 2012 Apr 26.

Biomedical Center and St. Petersburg State University, St. Petersburg, Russia.

Some individuals remain HIV seronegative despite repeated unprotected exposure to the virus. Recent observations led to a concept that acquired immunity plays a role in protection or at least in altered susceptibility to HIV-1 infection in highly exposed seronegative (ESN) individuals. Our aim was to study HIV-specific cellular immune responses induced in parenterally and/or heterosexually ESN individuals. Nine seronegative injection drug users (IDUs), 10 seronegative individuals, and nine of their HIV-positive sexual and/or IDU partners from the cohort of IDUs were included in the study. The discordant couples had unprotected sex, and some of seronegative partners also had parenteral exposure. Cell-mediated responses were measured in peripheral blood mononuclear cells (PBMCs) by ex vivo interferon (IFN)-γ-ELISpot and ICS combining IFN-γ, tumor necrosis factor (TNF)-α, and interleukin (IL)-2 after stimulation with four consensus peptide pools (Nef, Gag, RT, Env, subtype A-EE). Thirteen out of 19 (68%) seronegative study subjects had strong Nef peptide pool-specific ELISpot responses, three (16%) subjects responded against the Gag peptide pool, and one subject had an RT peptide pool response. Nef peptide pool responses in ESN were as high as in seropositive subjects. The multiple HIV-specific cytokine production in both CD4(+) and CD8(+) T cells was shown for several ESN subjects. The functional profiles of the immune responses were different between seronegative and HIV-positive study groups. Whether the observed cellular responses have any protective role against HIV needs to be further investigated.
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http://dx.doi.org/10.1089/aid.2011.0335DOI Listing
December 2012

catena-Poly[thorium(IV)-tetrakis(μ(2)-3-carboxyadamantane-1-carboxylato)]: a quadruple helical strand driven by a synergy of coordination and hydrogen bonding.

Acta Crystallogr C 2010 Oct 4;66(Pt 10):m276-9. Epub 2010 Sep 4.

Inorganic Chemistry Department, National Taras Shevchenko University of Kyiv, Volodimirska Street 64, Kyiv 01033, Ukraine.

The title compound, [Th(C(12)H(15)O(4))(4)](n), is the first homoleptic thorium-carboxylate coordination polymer. It has a one-dimensional structure supported by the bidentate bridging coordination of the singly charged 3-carboxyadamantane-1-carboxylate (HADC(-)) anions. The metal ion is situated on a fourfold axis (site symmetry 4) and possesses a square-antiprismatic ThO(8) coordination, including four bonds to anionic carboxylate groups [Th-O = 2.359 (2) Å] and four to neutral carboxyl groups [Th-O = 2.426 (2) Å], while a strong hydrogen bond between these two kinds of O-atom donor [O...O = 2.494 (3) Å] affords planar pseudo-chelated Th{CO(2)...HO(2)C} cycles. This combination of coordination and hydrogen bonding is responsible for the generation of quadruple helical strands of HADC(-) ligands, which are wrapped around a linear chain of Th(IV) ions [Th...Th = 7.5240 (4) Å] defining the helical axis.
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http://dx.doi.org/10.1107/S0108270110034785DOI Listing
October 2010