Condensed Matter

16 pages, 1403 KiB

Open AccessArticle

Theoretical Study of Vibrational Properties of Peptides: Force Fields in Comparison and Ab Initio Investigation

by Nicole Luchetti and Velia Minicozzi

Condens. Matter 2022, 7(3), 53; https://doi.org/10.3390/condmat7030053 - 15 Sep 2022

Viewed by 1756

Infrared (IR) spectroscopy is a valuable tool to obtain information about protein secondary structure. The far-infrared (FIR) spectrum is characterized by a complex combination of different molecular contributions which, for small molecules, may be interpreted with the help of quantum-mechanical (QM) calculations. Unfortunately, [...] Read more.

Infrared (IR) spectroscopy is a valuable tool to obtain information about protein secondary structure. The far-infrared (FIR) spectrum is characterized by a complex combination of different molecular contributions which, for small molecules, may be interpreted with the help of quantum-mechanical (QM) calculations. Unfortunately, the high computational cost of QM calculations makes them inapplicable to larger molecules, such as proteins and peptides. In this work, we present a theoretical study on the secondary structure, molecular properties, and vibrational spectra of different peptides, using both a classical and a QM approach. Our results show that the amide I main peak value, and related quantities, such as dipole strength (DS) and transition dipole moment (TDM), depends on protein secondary structure; in particular, from QM calculations arises that

α

-rich molecular systems present lower intensities than

β

-rich ones. Furthermore, it is possible to decouple and identify the intensity of the different contributions of the inter- and intra-molecular motions which characterize the FIR spectrum, starting from the results obtained with QM calculations. Full article

(This article belongs to the Special Issue Experimental Ideas for Novel FEL Facilities Based on Plasma Acceleration)

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13 pages, 3534 KiB

Open AccessArticle

Nonlinear Excitations in Ultracold Atoms Trapped in Triple Optical Lattices

by Pradosh Basu, Barun Halder, Sriganapathy Raghav and Utpal Roy

Condens. Matter 2022, 7(3), 52; https://doi.org/10.3390/condmat7030052 - 09 Sep 2022

Viewed by 1467

Abstract

Various solitary wave excitations are found for a Bose-Einstein condensate in presence of two hybrid potentials in the form of triple mixtures of optical lattices. One of these potentials comprises of a combination of two important lattice profiles, such as frustrated optical lattice [...] Read more.

Various solitary wave excitations are found for a Bose-Einstein condensate in presence of two hybrid potentials in the form of triple mixtures of optical lattices. One of these potentials comprises of a combination of two important lattice profiles, such as frustrated optical lattice and double-well super-lattice, within one. Another represents a composite lattice combination, resulting in a wider and deeper frustrated optical lattice. The dynamical equation for such a system is solved by the exact analytical method to obtain a bright solitary wave, periodic wave and cnoidal wave excitations. We also report Anderson localization, bifurcation of condensate at the center and a competition between two different types of localizations upon trap engineering. Dynamical and structural stability analyses are also carried out, which reveal the obtained solutions as extremely stable for structural noise incorporation and sufficiently stable for dynamical stability. These triple mixtures of optical lattices impart better tunability on the condensate profile, which has made this system a true quantum simulator. Full article

(This article belongs to the Special Issue Fluctuations and Highly Non-linear Phenomena in Superfluids and Superconductors III)

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17 pages, 3834 KiB

Open AccessArticle

Structural, Magnetic, and Electrical Properties and Magnetoresistance of Monovalent K-Substituted La_0.7Ba_0.3−_xK_xMnO₃ (x = 0 and 0.04) Manganite

by Amirah Zahrin, Nurul Atiqah Azhar, Norazila Ibrahim and Zakiah Mohamed

Condens. Matter 2022, 7(3), 51; https://doi.org/10.3390/condmat7030051 - 24 Aug 2022

Cited by 5 | Viewed by 1973

Abstract

The effects of K⁺ substitution at the Ba-site on the structural, magnetic, and electrical properties and magnetoresistance (MR) of La_0.7Ba_0.3_−xK_xMnO₃ (x = 0 and 0.04) manganites prepared via the solid-state method were [...] Read more.

The effects of K⁺ substitution at the Ba-site on the structural, magnetic, and electrical properties and magnetoresistance (MR) of La_0.7Ba_0.3_−xK_xMnO₃ (x = 0 and 0.04) manganites prepared via the solid-state method were investigated. Rietveld refinement of X-ray diffraction data confirmed that both samples were crystallized in the rhombohedral structure with the R3

\bar{c}

space group. In addition, the unit cell volume, V, and the average grain size also increased with K⁺ ions. Magnetization versus applied field (M–H) measurement was carried out, and the saturation magnetization (M_s) was found to increase from 1.81

μ_{B}

/f.u. (x = 0) to 4.11

μ_{B}

/f.u. (x = 0.04), implying that K⁺ ions strengthened the ferromagnetic (FM) interaction. Furthermore, the metal–insulator transition temperature, T_MI, increased from 257 K (x = 0) to 271 K (x = 0.04). The observed behaviour may be related to the enhancement of double-exchange (DE) interaction due to the increase in Mn-O-Mn bond angle and electronic bandwidth (W), favouring the increasing rate of the e_g electron hopping process. The fitting of the electrical resistivity data in the metallic region describes the significance of residual resistivity, electron–electron and electron–magnon scattering processes to elucidate the electronic transport properties. Within the insulating region, variable range hopping (VRH) and small polaron hopping (SPH) models are proposed to describe the conduction mechanism. Full article

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14 pages, 1472 KiB

Open AccessArticle

Moiré-like Superlattice Generated van Hove Singularities in a Strained CuO₂ Double Layer

by Artem O. Sboychakov, Kliment I. Kugel and Antonio Bianconi

Condens. Matter 2022, 7(3), 50; https://doi.org/10.3390/condmat7030050 - 23 Aug 2022

Cited by 1 | Viewed by 1593

Abstract

While it is known that the double-layer Bi

_{2}

Sr

_{2}

CaCu

_{2}

O

_{8 + y}

(BSCCO) cuprate superconductor exhibits a one-dimensional (1D) incommensurate superlattice (IS), the effect of IS on the electronic structure remains elusive. Following the recent shift of interest [...] Read more.

While it is known that the double-layer Bi

_{2}

Sr

_{2}

CaCu

_{2}

O

_{8 + y}

(BSCCO) cuprate superconductor exhibits a one-dimensional (1D) incommensurate superlattice (IS), the effect of IS on the electronic structure remains elusive. Following the recent shift of interest from an underdoped phase to optimum and overdoped phases in BSCCO by increasing the hole doping x, controlled by the oxygen interstitials concentration y, here we focus on the multiple splitting of the density of states (DOS) peaks and emergence of higher order van Hove singularities (VHS) due to the 1D incommensurate superlattice. It is known that the 1D incommensurate wave vector

q = ϵ b

(where

b

is the reciprocal lattice vector of the orthorhombic lattice) is controlled by the misfit strain between different atomic layers in the range

0.209

–

0.215

in BSCCO and in the range

0.209

–

0.25

in Bi

_{2}

Sr

_{2}

Ca

_{1 - x}

Y

_{x}

Cu

_{2}

O

_{8 + y}

(BSCYCO). This work reports the theoretical calculation of a complex pattern of VHS due to the 1D incommensurate superlattice with large 1D quasi-commensurate supercells with the wave vector

ϵ = 9 / η

in the range

36 > η > 43

. The similarity of the complex VHS splitting and appearing of higher order VHS in a mismatched CuO

_{2}

bilayer with VHS due to the moiré lattice in strained twisted bilayer graphene is discussed. This makes a mismatched CuO

_{2}

bilayer quite promising for constructing quantum devices with tuned physical characteristics. Full article

(This article belongs to the Section Superconductivity)

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11 pages, 340 KiB

Open AccessArticle

On Three “Anomalous” Measurements of Nonlinear QPC Conductance

by Mukunda P. Das and Frederick Green

Condens. Matter 2022, 7(3), 49; https://doi.org/10.3390/condmat7030049 - 10 Aug 2022

Cited by 1 | Viewed by 1361

Abstract

Practical mesoscopic devices based on quantum point contacts (QPCs) must function at operating point involving large internal driving fields. Experimental evidence has accumulated to display anomalous nonlinear features of QPC response beyond the capacities of accepted tunnelling-based models of nonlinear quantum transport. Here, [...] Read more.

Practical mesoscopic devices based on quantum point contacts (QPCs) must function at operating point involving large internal driving fields. Experimental evidence has accumulated to display anomalous nonlinear features of QPC response beyond the capacities of accepted tunnelling-based models of nonlinear quantum transport. Here, we recall the physical setting of three anomalous QPC experiments and review how, for two of them, a microscopically based nonequilibrium quantum kinetic description—the correct physical boundary conditions being crucial—has already overcome the predictive limitations of standard nonequilibrium mesoscopic models. The third experiment remains a significant challenge to all theorists. Full article

(This article belongs to the Special Issue New Advances in Condensed Matter Physics)

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8 pages, 1368 KiB

Open AccessArticle

MgB₂ Thin Films Fabricated by Pulsed Laser Deposition Using Nd:YAG Laser in an In Situ Two-Step Process

by Toshinori Ozaki, Satoshi Kikukawa, Rika Tanaka, Akiyasu Yamamoto, Akihiro Tsuruta and Yuji Tsuchiya

Condens. Matter 2022, 7(3), 48; https://doi.org/10.3390/condmat7030048 - 02 Aug 2022

Cited by 3 | Viewed by 2055

Abstract

Magnesium diboride (MgB₂) thin films on r-cut sapphire (r-Al₂O₃) single crystals were fabricated by a precursor, which was obtained at room temperature via a pulsed laser deposition (PLD) method using a Nd:YAG laser, and [...] Read more.

Magnesium diboride (MgB₂) thin films on r-cut sapphire (r-Al₂O₃) single crystals were fabricated by a precursor, which was obtained at room temperature via a pulsed laser deposition (PLD) method using a Nd:YAG laser, and an in situ postannealing process. The onset superconducting transition, T_c^onset, and zero-resistivity transition, T_c^zero, were observed at 33.6 and 31.7 K, respectively, in the MgB₂ thin films prepared by a Mg-rich target with a ratio of Mg:B = 3:2. The critical current density, J_c, calculated from magnetization measurements reached up to 0.9 × 10⁶ A cm⁻² at 20 K and 0 T. The broad angular J_c peak was found at 28 K when the magnetic fields were applied in a direction parallel to the film surface (θ = 90°). This could be indicative of the granular structure with randomly oriented grains. Our results demonstrate that this process is a promising candidate for the fabrication of MgB₂ superconducting devices. Full article

(This article belongs to the Special Issue Layered Superconductors III)

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18 pages, 3428 KiB

Open AccessReview

Identifying Redox Orbitals and Defects in Lithium-Ion Cathodes with Compton Scattering and Positron Annihilation Spectroscopies: A Review

by Johannes Nokelainen, Bernardo Barbiellini, Jan Kuriplach, Stephan Eijt, Rafael Ferragut, Xin Li, Veenavee Kothalawala, Kosuke Suzuki, Hiroshi Sakurai, Hasnain Hafiz, Katariina Pussi, Fatemeh Keshavarz and Arun Bansil

Condens. Matter 2022, 7(3), 47; https://doi.org/10.3390/condmat7030047 - 26 Jul 2022

Cited by 4 | Viewed by 2574

Abstract

Reduction-oxidation (redox) reactions that transfer conduction electrons from the anode to the cathode are the fundamental processes responsible for generating power in Li-ion batteries. Electronic and microstructural features of the cathode material are controlled by the nature of the redox orbitals and how [...] Read more.

Reduction-oxidation (redox) reactions that transfer conduction electrons from the anode to the cathode are the fundamental processes responsible for generating power in Li-ion batteries. Electronic and microstructural features of the cathode material are controlled by the nature of the redox orbitals and how they respond to Li intercalation. Thus, redox orbitals play a key role in performance of the battery and its degradation with cycling. We unravel spectroscopic descriptors that can be used to gain an atomic-scale handle on the redox mechanisms underlying Li-ion batteries. Our focus is on X-ray Compton Scattering and Positron Annihilation spectroscopies and the related computational approaches for the purpose of identifying orbitals involved in electrochemical transformations in the cathode. This review provides insight into the workings of lithium-ion batteries and opens a pathway for rational design of next-generation battery materials. Full article

(This article belongs to the Special Issue Rechargeable Batteries Studied Using Advanced Spectroscopic and Computational Techniques II)

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30 pages, 8920 KiB

Open AccessReview

Perspectives of Gas Phase Ion Chemistry: Spectroscopy and Modeling

by Mauro Satta, Mattea Carmen Castrovilli, Francesca Nicolanti, Anna Rita Casavola, Carlo Mancini Terracciano and Antonella Cartoni

Condens. Matter 2022, 7(3), 46; https://doi.org/10.3390/condmat7030046 - 21 Jul 2022

Cited by 2 | Viewed by 2379

Abstract

The study of ions in the gas phase has a long history and has involved both chemists and physicists. The interplay of their competences with the use of very sophisticated commercial and/or homemade instrumentations and theoretical models has improved the knowledge of thermodynamics [...] Read more.

The study of ions in the gas phase has a long history and has involved both chemists and physicists. The interplay of their competences with the use of very sophisticated commercial and/or homemade instrumentations and theoretical models has improved the knowledge of thermodynamics and kinetics of many chemical reactions, even if still many stages of these processes need to be fully understood. The new technologies and the novel free-electron laser facilities based on plasma acceleration open new opportunities to investigate the chemical reactions in some unrevealed fundamental aspects. The synchrotron light source can be put beside the FELs, and by mass spectrometric techniques and spectroscopies coupled with versatile ion sources it is possible to really change the state of the art of the ion chemistry in different areas such as atmospheric and astro chemistry, plasma chemistry, biophysics, and interstellar medium (ISM). In this manuscript we review the works performed by a joint combination of the experimental studies of ion–molecule reactions with synchrotron radiation and theoretical models adapted and developed to the experimental evidence. The review concludes with the perspectives of ion–molecule reactions by using FEL instrumentations as well as pump probe measurements and the initial attempt in the development of more realistic theoretical models for the prospective improvement of our predictive capability. Full article

(This article belongs to the Special Issue Experimental Ideas for Novel FEL Facilities Based on Plasma Acceleration)

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14 pages, 2436 KiB

Open AccessArticle

Nanocomposites Based on Cerium, Lanthanum, and Titanium Oxides Doped with Silver for Biomedical Application

by Olena Mykolaivna Lavrynenko, Maksym Mykytovych Zahornyi, Valeriia Volodymyrivna Vember, Olesia Yuriivna Pavlenko, Tatyana Fedorovna Lobunets, Olexandr Fedorovych Kolomys, Olga Yurievna Povnitsa, Luibov Oleksievna Artiukh, Krystyna Sergiivna Naumenko, Svitlana Dmitrievna Zahorodnia and Inna Leontievna Garmasheva

Condens. Matter 2022, 7(3), 45; https://doi.org/10.3390/condmat7030045 - 19 Jul 2022

Cited by 9 | Viewed by 2358

Abstract

Nanosized composites CeO₂–Ag, La₂O₃–Ag, and TiO₂–Ag are a class of nanomaterials suitable for photocatalysis, optical devices, and photoelectrochemical elements. Further, nanocomposites with several wt.% of silver can be used as creating materials for pathogenic virus [...] Read more.

Nanosized composites CeO₂–Ag, La₂O₃–Ag, and TiO₂–Ag are a class of nanomaterials suitable for photocatalysis, optical devices, and photoelectrochemical elements. Further, nanocomposites with several wt.% of silver can be used as creating materials for pathogenic virus inactivation with pandemic-neutralizing potential. Thus, CeO₂–Ag, La₂O₃–Ag, and TiO₂–Ag nanocomposites are prospective materials due to their optical and biological activity. In the present work, CeO₂–Ag, La₂O₃–Ag, and TiO₂–Ag nanocomposites were synthesized by the co-precipitation method. The morphological and optical properties and the structure of the prepared nanocomposites were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) with EDX, and nitrogen adsorption-desorption based on BET, Raman spectroscopy, and photoluminescence (PL). Both oxide matrixes corresponded to the cubic crystal lattice with the inclusion of argentum into the crystal lattice of oxides at relative low c(Ag) and reduction of silver on particle surface at 5 wt.% Ag and greater. The CeO₂, TiO₂, and La₂O₃ with a concentration of 4 wt.% Ag inhibited the growth processes of prokaryotic cells of E. coli, Bacillus sp., and S. aureus compared to pure oxides. Influenza A virus and herpes completely suppressed reproduction by nanocomposites of CeO₂–Ag (2, 5 wt.%) and La₂O₃–Ag (2, 5 wt.%) action. Full article

(This article belongs to the Special Issue Advances in Nanocomposite Materials)

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11 pages, 2556 KiB

Open AccessFeature PaperArticle

Effect of Metallic and Non-Metallic Additives on the Synthesis of Fullerenes in Thermal Plasma

by Anna Mária Keszler, Éva Kováts, Eszter Bódis, Zoltán Károly and János Szépvölgyi

Condens. Matter 2022, 7(3), 44; https://doi.org/10.3390/condmat7030044 - 30 Jun 2022

Cited by 1 | Viewed by 1610

Abstract

The effect of metallic (Fe, Cu, Co, Ni, Ti) and non-metallic additives (Si, B) on the formation of fullerenes from graphite powders was studied in radiofrequency (RF) thermal plasma. The main component of the synthesized fullerene mixtures was C₆₀, but higher [...] Read more.

The effect of metallic (Fe, Cu, Co, Ni, Ti) and non-metallic additives (Si, B) on the formation of fullerenes from graphite powders was studied in radiofrequency (RF) thermal plasma. The main component of the synthesized fullerene mixtures was C₆₀, but higher fullerenes (C₇₀, C₈₂, and C₈₄) could be detected as well. Fe and Cu additives increased the fullerene content in the soot. In contrast, the fullerene formation decreased in the presence of Ti, Si, and B as compared to the synthesis without additives. However, Ti and B addition enhanced the formation of higher fullerenes. We provide experimental evidence that decreasing the reactor pressure results in a lower yield of fullerene production, in accordance with thermodynamic calculations and numerical simulations published earlier. In the presence of titanium, a significant quantity of TiC was also formed as a by-product. The fullerene mixture synthesized with boron additives showed higher stability during storage in ambient conditions as compared to other samples. Full article

(This article belongs to the Special Issue Advances in Nanocomposite Materials)

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Condens. Matter, Volume 7, Issue 3 (September 2022) – 10 articles

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