276 results match your criteria: "St Petersburg University[Affiliation]"

CuAAC (Cu catalyzed azide-alkyne cycloaddition) click-reaction is a simple and powerful method for the post-synthetic modification of organometallic complexes of transition metals. This approach allows the selective introduction of additional donor sites or functional groups to the periphery of the ligand environment. This is especially important if a metalloligand with free donor sites, which are of the same nature as the primary site for the coordination of the primary metal, has to be created.

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G protein-coupled trace amine-associated receptors (TAAR) recognize different classes of amine compounds, including trace amines or other exogenous and endogenous molecules. Yet, most members of the TAAR family (TAAR2-TAAR9) are considered olfactory receptors involved in sensing innate odors. In this study, TAAR6 mRNA expression was evaluated in the brain transcriptomic datasets available in the GEO, Allen Brain Atlas, and GTEx databases.

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Background: The main aim of the research was to study short-term changes in the concentrations of elements in two widely distributed plant species, couch grass and nettle and in the rhizosphere soil of the plants.

Methods: The sampling of plants and soil was carried out on three dates: 3, 10, and 25 May 2021. On each day of sampling, the plants and soil were collected three times: at 9:00, 14:00, and 19:00.

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Metal-organic frameworks based surface-enhanced Raman spectroscopy technique for ultra-sensitive biomedical trace detection.

Nano Res

September 2022

Department of Instrument Science and Engineering, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China.

Metal-organic frameworks (MOFs) have attracted widespread interest due to their unique and unprecedented advantages in microstructures and properties. Besides, surface-enhanced Raman scattering (SERS) technology has also rapidly developed into a powerful fingerprint spectroscopic technique that can provide rapid, non-invasive, non-destructive, and ultra-sensitive detection, even down to single molecular level. Consequently, a considerable amount of researchers combined MOFs with the SERS technique to further improve the sensing performance and broaden the applications of SERS substrates.

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Trace amine-associated receptors (TAARs) are a family of G protein-coupled receptors present in mammals in the brain and several peripheral organs. Apart from its olfactory role, TAAR5 is expressed in the major limbic brain areas and regulates brain serotonin functions and emotional behaviours. However, most of its functions remain undiscovered.

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A Simple Contactless High-Frequency Electromagnetic Sensor: Proof of Concept.

Anal Chem

September 2022

Institute of Chemistry, St. Petersburg University, Universitetskiy pr. 26, St. Petersburg 198504, Russian Federation.

We report on the development of a very simple and inexpensive sensor device based on an inductance coil connected to a high-frequency electric field generator. The working principle of this sensor is as follows: liquid sample in a plastic tube is placed inside the inductance coil as its core and this core changes the properties of high-frequency electric current passing through the coil; these changes depend on sample conductivity, dielectric constant, magnetic properties, and capacitance. The electric signal registered after the coil represents a kind of a spectrum that can be effectively treated with chemometric tools.

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This study presents an analysis of growth data obtained using the BACTEC MGIT 960 system and respective mathematical models. The system is based on the detection of a decrease in oxygen level in the broth due to the bacterial respiration. It is shown that recordings sampled with a 1 hour rate provide an opportunity to distinguish between the oxygen consumption of growing cells and active cells division when the density of micro-organisms is sufficient to enter into the synchronized division mode.

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Trace Amine Associate Receptor 1 (TAAR1) as a New Target for the Treatment of Cognitive Dysfunction in Alzheimer's Disease.

Int J Mol Sci

July 2022

Department of Neuroscience, Research Institute for Health Science and Technology, University of Mons, 20 Place du Parc, 7000 Mons, Belgium.

Worldwide, approximately 27 million people are affected by Alzheimer's disease (AD). AD pathophysiology is believed to be caused by the deposition of the β-amyloid peptide (Aβ). Aβ can reduce long-term potentiation (LTP), a form of synaptic plasticity that is closely associated with learning and memory and involves postsynaptic glutamate receptor phosphorylation and trafficking.

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The insight phenomenon is thought to comprise two components: cognitive and affective (the Aha! experience). The exact nature of the Aha! experience remains unclear; however, several explanations have been put forward. Based on the processing fluency account, the source of the Aha! experience is a sudden increase in processing fluency, associated with emerging of a solution.

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Non-covalent interactions in the glutathione peroxidase active center and their influence on the enzyme activity.

Org Biomol Chem

July 2022

Institute of Chemistry, St. Petersburg University, Universitetskaya emb. 7/9, St. Petersburg, Russia.

In this computational work, the structure of the active center of the enzyme glutathione peroxidase (in three forms -SeH, -SeOH and -Se(O)OH) and the non-covalent interactions in it were investigated using modern quantum chemistry methods. The non-covalent interactions are described in detail. The presence of σ-hole interactions (chalcogen, tetrel and pnictogen bonds) formed mostly by a selenium atom as an electrophile in the glutathione peroxidase active center is confirmed for the first time.

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The manipulation of the photophysical properties of molecular emitters can be realized by composing the close environment of the metal center with the "heavier pnictogen atom" effect. Replacing a nitrogen atom with a heavier phosphorus atom in otherwise isostructural molecular systems results in a significant change of the photophysical parameters. Herein, we report on the synthesis of four pairs of novel phosphinine-based and isostructural diimine-based Cu(I) complexes, which feature peculiar photophysical properties, and show how these parameters depend on the "heavier pnictogen atom" effect.

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We report herein a family of polynuclear complexes, [Au@Ag(PyP)]X and [Au@Cu(PyP)]X [X = NO, ClO, OTf, BF, SbF], containing unprecedented Au-centered Ag and Cu tetrahedral cores supported by tris(2-pyridyl)phosphine (PyP) ligands. The [Au@Ag] clusters are synthesized controlled substitution of the central Ag(I) ion in all-silver [Ag@Ag] precursors by the reaction with Au()Cl, while the [Au@Cu] cluster is assembled through the treatment of a pre-organized [Au(PyP)] metallo-ligand with 4 equiv of a Cu(I) source. The structure of the Au@M clusters has been experimentally and theoretically investigated to reveal very weak intermolecular Au-M metallophilic interactions.

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(Lecithasteridae, Digenea) in the White Sea: an unnoticed guest from the Pacific?

J Helminthol

June 2022

Department of Invertebrate Zoology, St Petersburg University, Universitetskayia nab. 7-9, 199034, St Petersburg, Russia.

Morphological discrimination of species is problematic in many digenean taxa. Parasites of marine fish from the genus Lühe, 1901 are a good example of this. Our goal was to understand which species of infect fish in the White Sea, and reveal their life cycles.

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The protein α-synuclein, which is well-known for its links to Parkinson's Disease, is associated with synaptic vesicles (SVs) in nerve terminals. Despite intensive studies, its precise physiological function remains elusive. Accumulating evidence indicates that liquid-liquid phase separation takes part in the assembly and/or maintenance of different synaptic compartments.

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[Capabilities of using a multifunctional led device in the study of objects of forensic examination].

Sud Med Ekspert

May 2022

St. Petersburg Academy of the Investigative Committee of the Russian Federation, St. Petersburg, Russia.

The purpose of the work is to determine the capabilities of the modern multifunctional device «Photobox 3138» with LED illuminators with a high color rendering index for photofixation, colorimetric, spectrozonal and multispectral analyzes of forensic objects. The competencies of the «Photobox 3138» device were experimentally revealed in terms of visualization and photofixation of both traces of biological origin (blood, sweat fat, saliva, etc.) and traces of traditional examinations, including shot products, oil products.

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Hydrodynamic Characteristics and Conformational Parameters of Ferrocene-Terpyridine-Based Polymers.

Polymers (Basel)

April 2022

Department of Molecular Biophysics and Polymer Physics, St. Petersburg University, Universitetskaya Nab. 7/9, 199034 Saint-Petersburg, Russia.

Nowadays, the study of metallopolymers is one of the fastest growing areas of polymer science. Metallopolymers have great potential for application in multiple technological and various biomedical processes. The macromolecules with the possibility of varying the number and type of metal ions along the entire length of the polymer chain are of particular interest.

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The study of the aggregation of amyloid proteins is challenging. A new approach to processing dynamic light scattering data was developed and tested using aggregates of the well-known model Sup35NM amyloid. After filtering and calculating the moving averages of autocorrelation functions to reduce impacts of noise, each averaged autocorrelation function is converted to the fibril length distribution via numerical modeling.

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Trace amines are a group of biogenic amines that are structurally and functionally close to classical monoamine neurotransmitters. Trace amine-associated receptors (TAARs) are emerging as promising targets for treating neuropsychiatric disorders. It has been documented that all TAARs, apart from TAAR1, function as olfactory receptors involved in sensing innate odors encoded by volatile amines.

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Palladium(II) and platinum(II) complexes featuring metalla-N-heterocyclic carbenes (7-12) were synthesised metal-mediated coupling between equimolar -[MCl(CNR)] (R = 2,6-MeCH (Xyl), 2,4,6-MeCH (Mes)) and 2-aminopyridine or 2-aminopyrazine. Thiocyanate complexes 13-18 with two thiocyanate ligands were obtained through the ligand exchange in the parent compounds 7-12 with NHCNS in acetone/CHCl. Complexes 7-18 were isolated and characterised by HRESI-MS, IR, H and C{H} NMR spectroscopy and single-crystal X-ray diffraction (in the case of 11, 16, and 18).

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In this work we show, using the example of a series of [Cu(Xantphos)(N^N)] complexes (N^N being substituted 5-phenyl-bipyridine) with different peripheral N^N ligands, that substituents distant from the main action zone can have a significant effect on the physicochemical properties of the system. By using the C≡C bond on the periphery of the coordination environment, three hybrid molecular systems with -Si(CH), -Au(PR), and -CHN(CH)CH fragments were produced. The Cu(I) complexes thus obtained demonstrate complicated emission behaviour, which was investigated by spectroscopic, electrochemical, and computational methods in order to understand the mechanism of energy transfer.

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The contribution deals with the synthesis of the poly(methacrylate)-based copolymers, which contain ferrocene and/or terpyridine moieties in the side chains, and the subsequent analysis of their self-assembly behavior upon supramolecular/coordination interactions with Eu3+ and Pd2+ ions in dilute solutions. Both metal ions provoke intra and inter molecular complexation that results in the formation of large supra-macromolecular assembles of different conformation/shapes. By applying complementary analytical approaches (i.

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Transversal structural elements in cross-striated muscles, such as the M-band or the Z-disc, anchor and mechanically stabilize the contractile apparatus and its minimal unit-the sarcomere. The ability of proteins to target and interact with these structural sarcomeric elements is an inevitable necessity for the correct assembly and functionality of the myofibrillar apparatus. Specifically, the M-band is a well-recognized mechanical and signaling hub dealing with active forces during contraction, while impairment of its function leads to disease and death.

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Learning Your Options: Option-Based Model of Export Readiness and Optimal Export.

Entropy (Basel)

January 2022

National Economics Research Center (NERC), St.-Petersburg University, 7-9-11 Universitetskaya Embankment, 199034 St. Petersburg, Russia.

In this short note we offer a novel quantitative approach to modeling of early stages of firm's internalization, namely stages of accumulation of export readiness and their export debut. In particular, we introduce a new model of export readiness and offer an explicit way of how the export readiness can be accounted in the company share price. The model considers export readiness as a non-observable intangible asset that changes a firm's asset dynamics.

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Lizard Skin Patterns and the Ising Model.

Phys Rev Lett

January 2022

Department of Genetics and Evolution, University of Geneva, 30 quai Ernest-Ansermet, 1211 Genève, Switzerland.

The ocellated lizard (Timon lepidus) exhibits an intricate skin color pattern made of monochromatic black and green skin scales, whose dynamics of color flipping are known to be well modeled by a stochastic cellular automaton. We show that the late-time probability distribution of the pattern corresponds to the canonical probability distribution of the antiferromagnetic Ising model and can be generated by dynamics different from the commonly-used Glauber. We comment on skin scale patterns generated by the Ising model on the triangular lattice in the low-temperature limit.

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