85 results match your criteria: "Samarkand State University[Affiliation]"

Artificial intelligence to predict soil temperatures by development of novel model.

Sci Rep

April 2024

Department of Civil Engineering and Construction, Faculty of Engineering and Design, Atlantic Technological University, Sligo, F91 YW50, Ireland.

Soil temperatures at both surface and various depths are important in changing environments to understand the biological, chemical, and physical properties of soil. This is essential in reaching food sustainability. However, most of the developing regions across the globe face difficulty in establishing solid data measurements and records due to poor instrumentation and many other unavoidable reasons such as natural disasters like droughts, floods, and cyclones.

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In the present study, green synthesis of silver nanoparticles (VNE-AgNPs) via Verbascum nudatum extract was carried out for the first time. The synthesized AgNPs were characterized by different spectral methods such as UV-vis, FTIR, XRD, TEM, and EDAX. According to TEM analyses, the average size range of AgNPs was 17-21 nm, and the dominant peaks in the 111°, 200°, 221°, and 311° planes in the XRD pattern indicated the Ag-NPs FCC crystal structure.

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The origins and dispersal of the chicken across the ancient world remains one of the most enigmatic questions regarding Eurasian domesticated animals. The lack of agreement concerning timing and centers of origin is due to issues with morphological identifications, a lack of direct dating, and poor preservation of thin, brittle bird bones. Here we show that chickens were widely raised across southern Central Asia from the fourth century BC through medieval periods, likely dispersing along the ancient Silk Road.

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At first, an organometallic catalyst namely, Pd-DPyE@MCM-41@MNP was prepared through magnetic (FeO) nanoparticles-doped into channels of mesoporous silica MCM-41 and then, anchoring a novel complex composed of di(4-pyridyl)ethylene and palladium on the inner surface of the support. This immobilized catalyst was successfully identified via VSM, ICP-OES, TEM, FTIR, TGA, SEM, BET, XRD, EDX and elemental mapping analyses. After that, it was used as a versatile, heterogeneous, and magnetically reproducible catalyst in the generation of N,N'-alkylidene bisamides (1a-13a, 8-20 min, 90-98%, 50 °C, solvent-free) and Suzuki-Miyaura coupling (SMC) reaction derivatives (1b-26b, 10-140 min, 86-98%, 60 °C, PEG-400).

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Proton therapy has emerged as an advantageous modality for tumor radiotherapy due to its favorable physical and biological properties. However, this therapy generates induced radioactivity through nuclear reactions between the primary beam, secondary particles, and surrounding materials. This study focuses on systematically investigating the induced radioactivity in the gantry room during pencil beam scanning, utilizing both experimental measurements and Monte Carlo simulations.

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This study describes a robust chromatographic authentication methodology for herbaceous pollen, employing gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC) and high-performance thin liquid chromatography (HPTLC) protocols. The comprehensive profiling of organic compounds not only distinguishes between different botanical sources but also establishes a reliable framework for quality control and assessment of herbaceous pollen authenticity. Traces of quercetin were detectable using HPTLC in Chaenomeles japonica, and the composition of the mobile phase led to distinct phenolic acid tracks in the extracts of free phenolic compounds.

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Light-induced photodissociation in the lowest three electronic states of the NaH molecule.

Phys Chem Chem Phys

February 2024

Department of Theoretical Physics, Doctoral School of Physics, University of Debrecen, PO Box 400, H-4002 Debrecen, Hungary.

It has been known that electronic conical intersections in a molecular system can also be created by laser light even in diatomics. The direct consequence of these light-induced degeneracies is the appearance of a strong mixing between the electronic and vibrational motions, which has a strong fingerprint on the ultrafast nuclear dynamics. In the present work, pump and probe numerical simulations are performed with the NaH molecule involving the first three singlet electronic states (XΣ(X), AΣ(A) and BΠ(B)) and several light-induced degeneracies in the numerical description.

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A new fifteen-level stepped DC to AC hybrid converter is proposed for Solar Photovoltaic (SPV) applications. A boost chopper circuit is designed and interfaced with the fifteen-level hybrid converters specific to Electric Vehicles' Brushless DC Motor (BLDC) drive systems. In chopper units, the output of solar panels is regulated and stepped up to obtain the nominal output voltage.

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Microscopic techniques can be applied to solve taxonomic problems in the field of plant systematic and are extremely versatile in nature. This study was focused on the new approaches to visualizing the imaging, tool to cover the micro-structural techniques applied to the pollen study of flowers. The current research was proposed to evaluate microscopic pollen morphological attributes using light and scanning electron microscopy of herbaceous flora from Samarkand, Uzbekistan.

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Types of noncovalent bonds within complexes of thiazole with CF and SiF.

Phys Chem Chem Phys

February 2024

Department of Optics and Spectroscopy, Institute of Engineering Physics Samarkand State University 140104, University blv. 15, Samarkand, Uzbekistan.

The five-membered heteroaromatic thiazole molecule contains a number of electron-rich regions that could attract an electrophile, namely the N and S lone pairs that lie in the molecular plane, and π-system areas above the plane. The possibility of each of these sites engaging in a tetrel bond (TB) with CF and SiF, as well as geometries that encompass a CH⋯F H-bond, was explored DFT calculations. There are a number of minima that occur in the pairing of thiazole with CF that are very close in energy, but these complexes are weakly bound by less than 2 kcal mol and the presence of a true TB is questionable.

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The taxonomic relationship between the genera Phragmataecia Newman, 1850 and Phragmacossia Schawerda, 1924 is considered. Diagnostic characters and distribution of the species Phragmataecia castaneae (Hbner, 1790), Phragmataecia albida (Erschoff, 1874), Phragmacossia ariana (Grum-Grshimailo, 1899), Phragmacossia territa (Staudinger, 1879), and Phragmacossia minos Reisser, 1963 are studied in detail. A new species, Phragmacossia bozanoi sp.

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Membrane technology has been embraced as a feasible and suitable substitute for conventional time- and energy-intensive biodiesel synthesis processes. It is ecofriendly, easier to run and regulate, and requires less energy than conventional approaches, with excellent stability. Therefore, the present study involved the synthesis and application of a highly reactive and recyclable Titania-based heterogeneous nanocatalyst (TiO) for biodiesel production from nonedible seed oil via a membrane reactor, since is easily and widely accessible and has a rich oil content (39% /).

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Micrometer insights into Nepeta genus: Pollen micromorphology unveiled.

Micron

February 2024

Department of Medicinal Plants, Tashkent State Agrarian University, 2 A., Universitet Str., 100700, Uzbekistan.

This study provides a comprehensive pollen micromorphology within the Nepeta genus, revealing intricate details about the pollen grains' structure and characteristics. The findings shed light on the evolutionary and taxonomical aspects of this plant genus, offering valuable insights for botanists and researchers studying Nepeta species. The pollen grains of 18 Nepeta species were studied using scanning electron microscopy (SEM) and light microscopy (LM) in Northern Pakistan.

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Thermal and biological properties of novel sodium carboxymethylcellulose-PPFMA nanocomposites containing biosynthesized Ag-ZnO hybrid filler.

Int J Biol Macromol

February 2024

Samarkand State University, Institute of Biochemistry, Department of Organic Synthesis and Bioorganic Chemistry, University blvd-15, Samarkand, Uzbekistan; Samarkand State University, Institute of Biochemistry, Department of Polymer Chemistry and Chemical Technology, University Blvd-15, Samarkand, Uzbekistan. Electronic address:

The aim of this study was to produce new nanocomposites with antimicrobial, antioxidant and anticancer properties that can be used in biomedical research based on carboxymethyl cellulose (NaCMC) biopolymer. First, poly(2-oxo-2-(pentafluorophenoxy)ethyl-2-methylprop-2-enoate) (PPFMA) was synthesized and characterized by FTIR and NMR techniques. It was then blended with NaCMC by in situ/hydrothermal method to produce a semi-synthetic functional material.

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Background: The mountainous region of Kashmir is a biodiversity hotspot, with diverse local communities and a rich cultural history linked to nature. Mountain ecosystems are highly vulnerable to climate change. This study emphasises the need to record the indigenous ethnoecological knowledge of wild plants used for the treatment of various ailments at higher elevations in remote areas where globalisation poses a threat to this traditional knowledge.

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Relation between Halogen Bond Strength and IR and NMR Spectroscopic Markers.

Molecules

November 2023

Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA.

The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C-X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds.

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Considering the limited data available on tree species in Uzbekistan, this research aimed to provide new insights. We gathered plant samples from different locations within Samarkand city and thoughtfully selected 15 tree species that represent the country's flora. Using scanning electron microscopy, we conducted comprehensive analyses of pollen morphology, revealing a diverse range of variations in the shapes, dimensions, and surface characteristics displayed by pollen grains.

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This study investigates soil radioactivity at the Pomuk gas field in Uzbekistan, a region with history of underground nuclear activity. Using a NaI (Tl) scintillation gamma spectrometer, soil samples were analyzed for concentrations of Th, Ra, K, and Cs. Concentrations were found to be in the range of 19.

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Heavy pnicogen atoms as electron donors in sigma-hole bonds.

Phys Chem Chem Phys

September 2023

Department of Chemistry and Biochemistry, Utah State University Logan, Utah 84322-0300, USA.

DFT calculations evaluate the strength of σ-hole bonds formed by ZH and ZMe (Z = N, P, As, Sb) acting as electron donor. Bond types considered include H-bond, halogen, chalcogen, pnicogen, and tetrel bond to perfluorinated Lewis acids FH, FBr, FSe FAs, FGe, respectively, as well as their monofluorinated analogues. All of the Z atoms can engage in bonds of at least moderate strength, varying from 3 to more than 40 kcal mol.

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Competition between Binding to Various Sites of Substituted Imidazoliums.

J Phys Chem A

August 2023

Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, United States.

The imidazolium cation has a number of different sites that can interact with a nucleophile. Adding a halogen atom (X) or a chalcogen (YH) group introduces the possibility of an NX···nuc halogen or NY···nuc chalcogen bond, which competes against the various H-bonds (NH and CH donors) as well as the lone pair···π interaction wherein the nucleophile lies above the plane of the cation. Substituted imidazoliums are paired with the NH base, and the various different complexes are evaluated by density functional theory (DFT) calculations.

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This study examines the role of light microscopic (LM) and scanning electron microscopic (SEM) micromorphological traits of the epidermis in identifying and classifying invasive plants. SEM was conducted to increase our understanding of microscopic qualities that are not visible in light microscopy and to elucidate unclear affinities among invasive species. The study examines invasive species' morphological and anatomical characteristics from the Pothohar Plateau of Pakistan for the first time.

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A Radiative Chemical Process for the Methylene Blue Degradation by Natural Convective Nanofluid Flow over an Upright Cone.

ScientificWorldJournal

July 2023

Department of Mathematical Modeling, Faculty of Mathematics, Samarkand State University, University Boulevard 15, Samarkand 140104, Uzbekistan.

An upstraight cone with nonisothermal surface velocity, temperature, and concentration was investigated using a numerical solution approach to simulate MHD, MB dye, and various nanofluid flows. Numerical evaluation of the flow field equation was carried out using an excellent finite difference method after it has been converted into a dimensionless form. Different heat transfer occurrences were observed depending on temperature, velocity, and concentration when using several types of nanofluids (TiO, Ag, Cu, and AlO).

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