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Crystals, Volume 12, Issue 7 (July 2022) – 137 articles

Cover Story (view full-size image): AA 6086 is a wrought Al-Mg-Si alloy with a tensile strength and elongation exceeding 480 MPa and 10%, respectively. The additions of 0.2 and 1 wt.% Sc strongly reduced the grain size and induced the appearance of the Sc-rich phases AlSc2Si2 and L12-Al3X. Most primary phases dissolved, and different dispersoids formed during homogenization. The distribution of dispersoids was not uniform in the alloy with 0.2% Sc. The large plate-like α-AlMnSi dispersoids and spherical L12 precipitates formed at dendrite centres, while smaller α-AlMnSi and tetragonal t-Al3Zr dispersoids were created elsewhere. The precipitation was slightly delayed during isothermal ageing and shifted to higher temperatures during continuous heating. Scandium did not considerably affect the hardness of the investigated alloy. View this paper
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12 pages, 5696 KiB  
Article
Solution-Mediated Polymorphic Transformation of L-Carnosine from Form II to Form I
by Yanan Zhou, Shuyi Zong, Jie Gao, Chunsong Liu and Ting Wang
Crystals 2022, 12(7), 1014; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071014 - 21 Jul 2022
Cited by 2 | Viewed by 1399
Abstract
In this study, L-carnosine was chosen as the model compound to systematically study solution-mediated polymorphic transformation by online experiment and theoretical simulation. Form II, a new polymorph of L-carnosine, was developed using an antisolvent crystallization method. The properties of form I and form [...] Read more.
In this study, L-carnosine was chosen as the model compound to systematically study solution-mediated polymorphic transformation by online experiment and theoretical simulation. Form II, a new polymorph of L-carnosine, was developed using an antisolvent crystallization method. The properties of form I and form II L-carnosine were characterized by powder X-ray diffraction, polarizing microscope, thermal analysis, and Raman spectroscopy. In order to explore the relative stability, the solubility of L-carnosine form I and form II in a (water + DMAC) binary solvent mixture was determined by a dynamic method. During the solution-mediated polymorphic transformation process of L-carnosine in different solvents, Raman spectroscopy was employed to detect the solid-phase composition of suspension in situ, and the gravimetric method was used to measure the liquid concentration. In addition, the effect of the solvent on the transformation process was evaluated and analyzed. Finally, a mathematical model of dissolution–precipitation was established to simulate the kinetics of the polymorphic transformation process based on the experimental data. Taking the simulation results and the experimental data into consideration, the controlling step of solution-mediated polymorphic transformation was discussed. Full article
(This article belongs to the Special Issue Polymorphism in Crystals)
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12 pages, 6420 KiB  
Article
Alkali−Silica Activity and Inhibition Measures of Concrete Aggregate in Northwest China
by Jing Wen, Jinmei Dong, Chenggong Chang, Xueying Xiao and Weixin Zheng
Crystals 2022, 12(7), 1013; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071013 - 21 Jul 2022
Cited by 3 | Viewed by 1217
Abstract
The alkali−silica reaction (ASR)-induced expansion of mortar bars containing four types of aggregates originating from different regions in northwest China was studied. The chemical composition, mineral composition, vitreous and amorphous substances, and expansion rates were determined using X-ray fluorescence, X-ray diffraction, polarizing microscope [...] Read more.
The alkali−silica reaction (ASR)-induced expansion of mortar bars containing four types of aggregates originating from different regions in northwest China was studied. The chemical composition, mineral composition, vitreous and amorphous substances, and expansion rates were determined using X-ray fluorescence, X-ray diffraction, polarizing microscope images, and the accelerated mortar bar test (AMBT). The inhibitory effects of fly ash and silica fume on the aggregate activity were evaluated. The binary mortar mixes were produced and tested, containing cement and fly ash or silica fume as the partial cement replacement. The microstructure and composition of the ASR products were analyzed by scanning electron microscope energy dispersive spectroscopy (SEM–EDS). The results show that all four types of aggregates exhibited an alkali activity, and that all expansion rates on the 14th day were higher than the standard of 0.1%. The lowest and highest values were 0.2% and 0.3%, respectively. The primary constituent in the chemical compositions of these aggregates was found to be silica. Polarization microscopy also confirmed that they contained alkali-active cryptolites. Fly ash and silica fume could both inhibit alkali activity expansion and the silica fume exhibited a superior inhibition effect. When the fly ash and silica fume contents were 20% and 10%, respectively, the expansion rates of the mortar bar on the 14th day were all less than 0.03%. Full article
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4 pages, 184 KiB  
Editorial
Editorial on Special Issue “Performance Prediction, Durability and Modelling of Concrete Materials and Structures”
by Yang Yu, Weiqiang Wang, Rafael Shehu and Beatrice Pomaro
Crystals 2022, 12(7), 1012; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071012 - 21 Jul 2022
Viewed by 988
Abstract
Concrete is one of the construction industry’s most essential and commonly used materials [...] Full article
28 pages, 9165 KiB  
Review
Principles of Selective Area Epitaxy and Applications in III–V Semiconductor Lasers Using MOCVD: A Review
by Bin Wang, Yugang Zeng, Yue Song, Ye Wang, Lei Liang, Li Qin, Jianwei Zhang, Peng Jia, Yuxin Lei, Cheng Qiu, Yongqiang Ning and Lijun Wang
Crystals 2022, 12(7), 1011; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071011 - 21 Jul 2022
Cited by 5 | Viewed by 3126
Abstract
Selective area epitaxy (SAE) using metal–organic chemical vapor deposition (MOCVD) is a crucial fabrication technique for lasers and photonic integrated circuits (PICs). A low-cost, reproducible, and simple process for the mass production of semiconductor lasers with specific structures was realized by means of [...] Read more.
Selective area epitaxy (SAE) using metal–organic chemical vapor deposition (MOCVD) is a crucial fabrication technique for lasers and photonic integrated circuits (PICs). A low-cost, reproducible, and simple process for the mass production of semiconductor lasers with specific structures was realized by means of SAE. This paper presents a review of the applications of SAE in semiconductor lasers. Growth rate enhancement and composition variation, which are two unique characteristics of SAE, are attributed to a mask. The design of the mask geometry enables the engineering of a bandgap to achieve lasing wavelength tuning. SAE allows for the reproducible and economical fabrication of buried heterojunction lasers, quantum dot lasers, and heteroepitaxial III–V compound lasers on Si. Moreover, it enables the fabrication of compact photonic integrated devices, including electro-absorption modulated lasers and multi-wavelength array lasers. Results show that SAE is an economical and reproducible method to fabricate lasers with desired structures. The goals for SAE applications in the future are to improve the performance of lasers and PICs, including reducing the defects of the grown material introduced by the SAE mask and achieving precise control of the thickness and composition. Full article
(This article belongs to the Special Issue Frontiers of Semiconductor Lasers)
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20 pages, 5386 KiB  
Article
Biosynthesis of Silver Nanoparticles Using Bersama engleriana Fruits Extracts and Their Potential Inhibitory Effect on Resistant Bacteria
by Michele Stella Majoumouo, Marius Belmondo Tincho, Youmbi Diane Yimta, Tayo Alex Adekiya, Raphael Taiwo Aruleba, Nimibofa Ayawei, Fabrice Fekam Boyom and Thureyah Morris
Crystals 2022, 12(7), 1010; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071010 - 21 Jul 2022
Cited by 1 | Viewed by 1634
Abstract
The absence of novel, safe, and effective bactericide is an urgent concern worldwide and remains a challenge in scientific communities. The unique proprieties of silver nanoparticles (SNPs) synthesized from plant extracts make them a suitable candidate to overcome these limitations. Herein, we synthesized [...] Read more.
The absence of novel, safe, and effective bactericide is an urgent concern worldwide and remains a challenge in scientific communities. The unique proprieties of silver nanoparticles (SNPs) synthesized from plant extracts make them a suitable candidate to overcome these limitations. Herein, we synthesized SNPs from Bersama engleriana fruit (BEfr) extracts and determined their potential antibacterial activity and mode of action. SNPs were synthesized from BEfr methanolic fruit extracts at 25 and 70 °C, and the antibacterial effectiveness of SNPs against bacterial strains was investigated. The surface plasmon resonance peaked at 430.18 and 434.08 nm, respectively, for SNPs synthesized at 25 and 70 °C, confirming SNPs synthesis. BEfr-SNPs had minimum inhibitory concentrations (MIC) range of 0.234 to >50 µg/mL, which was 30-fold greater than extract alone (MIC of 500 µg/mL). BEfr-SNPs-25 °C was potent against six bacterial strains (S. aureus, S. enterica, MRS. aureus, K. pneumonia, and S. pyogenes), with MIC range of 0.339 to 6.25 µg/mL. The mode of action of BEfr-SNPs-25 °C was achieved by an MRSA bacteria strain outer membrane and DNA nucleotide linkage. These results suggest that our synthesized SNPs, especially BEfr-SNPs-25 °C, demonstrated an enhanced antibacterial effect and could be potential candidates for bacterial infection treatment. Full article
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18 pages, 3268 KiB  
Review
Review of Radiation-Induced Effects on β-Ga2O3 Materials and Devices
by Nethala Manikanthababu, Hardhyan Sheoran, Pradeep Siddham and Rajendra Singh
Crystals 2022, 12(7), 1009; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071009 - 21 Jul 2022
Cited by 14 | Viewed by 3023
Abstract
β-Ga2O3 has become an ultimate choice of emerging new-generation material for its wide range of compelling applications in power electronics. In this review, we have explored the available radiations in the atmosphere and the effects of radiation on the β-Ga [...] Read more.
β-Ga2O3 has become an ultimate choice of emerging new-generation material for its wide range of compelling applications in power electronics. In this review, we have explored the available radiations in the atmosphere and the effects of radiation on the β-Ga2O3 material and devices. The focus in this review summarizes various studies covering different radiation such as swift heavy ions, protons, neutrons, electrons, Gamma, and X-rays to understand the radiation-induced effects on the structure and their reliable performance in harsh environments. In addition, we focused on the various pre-existing defects in β-Ga2O3 and the emergence of radiation-induced defects that provoke a severe concern, especially from the device performance point of view. This review presents the irradiation-induced effects on the devices such as high-power devices such as Schottky barrier diodes (SBDs), field-effect transistors (FETs), metal-oxide-semiconductor (MOS) devices, and photodetectors. Some key studies including the changes in carrier concentration with a removal rate, Schottky barrier height (SBH), ideality factor, defect dynamics dielectric damage, interface charge trapping, a thermally activated recovery mechanism for charge carriers at elevated temperature, and diffusion length of minority charge carriers. These reports show that β-Ga2O3-based devices could be deployable for space or high-radiation terrestrial applications. These results provide/suggest a better device design based on the radiation degradation studies in the state-of-the-art β-Ga2O3 devices. Full article
(This article belongs to the Special Issue Defects in Wide Bandgap Semiconductors)
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8 pages, 1833 KiB  
Article
Pressure Induced Disorder-Order Phase Transitions in the Al4Cr Phases
by Changzeng Fan, Xu Geng and Bin Wen
Crystals 2022, 12(7), 1008; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071008 - 21 Jul 2022
Cited by 1 | Viewed by 1236
Abstract
An ordered ω-Al4Cr phase synthesized recently by a high-pressure sintering (HPS) approach was calculated to be stable by density function theory (DFT), implying that high pressure can accelerate the disorder-order phase transitions. The structural building units of the ω-Al4Cr [...] Read more.
An ordered ω-Al4Cr phase synthesized recently by a high-pressure sintering (HPS) approach was calculated to be stable by density function theory (DFT), implying that high pressure can accelerate the disorder-order phase transitions. The structural building units of the ω-Al4Cr phase as well as the non-stoichiometric disordered ε-Al4Cr and μ-Al4Cr phases have been analyzed by the topological “nanocluster” method in order to explore the structural relations among these phases. Both the ε-and μ-Al4Cr phases contain the typical Macky or pseudo-Macky cluster, and their centered positions were all occupied by Cr atoms, which all occupy the high-symmetry Wyckoff positions. The mechanism of the pressure-induced disorder-order phase transitions from the ε-/μ-Al4Cr to the ω-Al4Cr phase has been analyzed. and the related peritectic and eutectoid reactions have been re-evaluated. All results suggest that the stable ω-Al4Cr phase are transformed from the μ-Al4Cr phase by the eutectoid reaction that is accelerated by high-pressure conditions, whereas the ε-Al4Cr phase should form by the peritectic reaction. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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10 pages, 2882 KiB  
Article
Effects of Pre-Annealing on the Radiation Resistance of ZnO Nanorods
by Tengfei Wu, Aiji Wang, Mingyu Wang, Yinshu Wang, Zilin Liu, Yiwen Hu, Zhenglong Wu and Guangfu Wang
Crystals 2022, 12(7), 1007; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071007 - 21 Jul 2022
Cited by 1 | Viewed by 1116
Abstract
Ion implantation is usually used for semiconductor doping and isolation, which creates defects in semiconductors. ZnO is a promising semiconductor and has a variety of applications, such as for use in transparent electronics, optoelectronics, chemical and biological sensors, etc. In this work, ZnO [...] Read more.
Ion implantation is usually used for semiconductor doping and isolation, which creates defects in semiconductors. ZnO is a promising semiconductor and has a variety of applications, such as for use in transparent electronics, optoelectronics, chemical and biological sensors, etc. In this work, ZnO nanorods were grown on Si (100) substrates by the process of chemical bath deposition and then annealed in an O2 atmosphere at 350 and 600 °C for 1 h to introduce different kinds of defects. The as-grown nanorods and the nanorods that annealed were irradiated simultaneously by 180 keV H+ ions at room temperature with a total dose of 8.0×1015 ions/cm2. The radiation effects of the H+ ions, effects of the pre-existed defects on the radiation resistance, and the related mechanisms under irradiation were investigated. The crystal and optical properties of the ZnO nanorods after H+ ion irradiation were found to depend upon the pre-existed defects in the nanorods. The existence of the appropriate concentration of oxygen interstitials in the ZnO nanorods caused them to have good radiation resistance. The thermal effects of irradiation played an important role in the property variation of nanorods. The temperature of the nanorods under 180 keV H+ ion bombardment was around 350 °C. Full article
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21 pages, 1685 KiB  
Review
Research Progress of Monolithic Integrated DFB Laser Arrays for Optical Communication
by Shen Niu, Yue Song, Ligong Zhang, Yongyi Chen, Lei Liang, Ye Wang, Li Qin, Peng Jia, Cheng Qiu, Yuxin Lei, Yubing Wang, Yongqiang Ning and Lijun Wang
Crystals 2022, 12(7), 1006; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071006 - 21 Jul 2022
Cited by 6 | Viewed by 2543
Abstract
Photonic integrated circuits (PICs) play a leading role in modern information and communications technology. Among the core devices in PICs is the distributed feedback (DFB) multi-wavelength semiconductor laser array. Multi-wavelength semiconductor laser arrays can be integrated on a single chip and have the [...] Read more.
Photonic integrated circuits (PICs) play a leading role in modern information and communications technology. Among the core devices in PICs is the distributed feedback (DFB) multi-wavelength semiconductor laser array. Multi-wavelength semiconductor laser arrays can be integrated on a single chip and have the advantages of high stability, good single-mode performance, and narrow line width. The wavelength tuning range has been expanded through the design of the DFB laser array, which is an ideal light source for wavelength-division multiplexing systems. The preparation of DFB laser arrays with a large number of channels, ease of mass production, and accurate emission wavelengths has become an important field of research. The connection methods of lasers in DFB laser arrays are introduced systematically and the current methods of manufacturing multi-wavelength DFB laser arrays covering the perspective of technical principles, technical advantages and disadvantages, main research progress, and research status are summarized. Full article
(This article belongs to the Special Issue Frontiers of Semiconductor Lasers)
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15 pages, 3980 KiB  
Article
Influence of Organic-Modified Inorganic Matrices on the Optical Properties of Palygorskite–Curcumin-Type Hybrid Materials
by Florentina Monica Raduly, Valentin Rădițoiu, Radu Claudiu Fierăscu, Alina Rădițoiu, Cristian Andi Nicolae and Violeta Purcar
Crystals 2022, 12(7), 1005; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071005 - 20 Jul 2022
Cited by 2 | Viewed by 1393
Abstract
Clays are very important from an economic and application point of view, as they are suitable hosts for organic compounds. In order to diversify the fields of application, they are structurally modified by physical or chemical methods with cationic species, and/or different bifunctional [...] Read more.
Clays are very important from an economic and application point of view, as they are suitable hosts for organic compounds. In order to diversify the fields of application, they are structurally modified by physical or chemical methods with cationic species, and/or different bifunctional compounds, such as organosilanes. In this study, palygorskite was modified with (3-Aminopropyl) triethoxysilane, which was subsequently modified at the amino group by grafting an acetate residue. By using this strategy, two types of host hybrid materials were obtained on which curcumin derivatives were deposited. The composites obtained were structurally characterized and their photophysical properties were investigated in relation to the structure of the host matrices and interactions with curcumin-type visiting species. The hybrid composites have different colors (orange, yellow, pink), depending on the polarity of the inorganic matrices modulated by different organic groups grafted at the surface. Fluorescence emission in the visible range is characterized by the presence of two emission maxima, one belonging to the chromophore and the other influenced by the physical interactions between auxochromes and host matrices. These hybrid materials, compared to other composite structures, are obtained by a simple adsorption process. They are temperature stable in aggressive environments (acid/base) and render the fluorescent properties of dyes redundant, with improved luminescent performance compared to them. Full article
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19 pages, 1876 KiB  
Article
Effective Elasticity Tensor of Fiber-Reinforced Orthorhombic Composite Materials with Fiber Distribution Parallel to Plane
by Aimin Li, Tengfei Zhao, Zhiwen Lan and Mojia Huang
Crystals 2022, 12(7), 1004; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071004 - 20 Jul 2022
Viewed by 1228
Abstract
An orthogonal composite material Ω with fibers consists of a matrix and orthothombic distribution fibers. In addition to the matrix properties, the fiber properties and the fiber volume fraction, the effective (macroscopic) elastic stress–strain constitutive relation of Ω is related to the fiber [...] Read more.
An orthogonal composite material Ω with fibers consists of a matrix and orthothombic distribution fibers. In addition to the matrix properties, the fiber properties and the fiber volume fraction, the effective (macroscopic) elastic stress–strain constitutive relation of Ω is related to the fiber direction distribution. Until now, there have been few papers that give an explicit formula of the macroscopic elastic stress–strain constitutive relation of Ω with the effect of the fiber direction distribution. Taking the expanded coefficients of the Fourier series as the fiber direction distribution coefficients, we give a formula of the fiber direction distribution parallel to a plane computed through the fiber directions. By the self-consistent estimates, we derive an explicit formula of the macroscopic elastic stress–strain constitutive relation of Ω with the fiber direction distribution coefficients. Since all tensors are represented in Kelvin notation, the macroscopic elastic stress–strain constitutive relation of Ω can be derived and computed only by matrix manipulations. To check the explicit formula, we use the FEM computation to obtain the macroscopic elastic stress–strain relation of Ω for three examples. The computational results of the explicit formula for the three examples are consistent with those of the FEM simulations. Full article
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20 pages, 5220 KiB  
Review
Path Dependency of Plastic Deformation in Crystals: Work Hardening, Crystallographic Rotation and Dislocation Structure Evolution
by Zhen-Wei Zhang, Zheng Li, Ying Liu and Jing-Tao Wang
Crystals 2022, 12(7), 999; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070999 - 19 Jul 2022
Cited by 4 | Viewed by 2213
Abstract
This paper reviewed the research progress of studies on the crystal rotation of single crystals that were deformed by tension and shear and the influences of crystal rotation and dislocation evolution on strain hardening behavior in crystals that were deformed with different initial [...] Read more.
This paper reviewed the research progress of studies on the crystal rotation of single crystals that were deformed by tension and shear and the influences of crystal rotation and dislocation evolution on strain hardening behavior in crystals that were deformed with different initial orientations. The crystal rotation is entirely different depending on whether the single crystal was deformed by tension or shear. A three-stage work hardening behavior, which is not one of the intrinsic properties of materials, is generated when FCC metallic single crystals are deformed by tension along unstable oriFigurFigurentations, but single crystals do not exhibit this three-stage hardening behavior when they are deformed by simple shear at room temperature. Under tension, crystal rotation causes the transition from work hardening stage I to stage II, while the transition from work hardening stage II to III is caused by dislocation evolution. The evolution of the dislocation structure is related to deformation loading and can be classified into three types when a crystal is deformed by tension. Different from tension, shear stress can directly act on one of the 12 slip systems when a crystal is deformed by simple shear. When FCC single crystals are deformed by shear along the (11¯1)[110], (111)[112¯] and (001)[110] orientations, the single slip system, co-planar slip systems and co-directional slip systems are activated, respectively, and the crystals hardly rotate under the shear conditions. The slip direction of [110] forces the crystal to rotate toward the shear direction under simple shear. The dislocation tangles tend to form the dislocation cells and wall structures when multiple slip systems are activated under simple shear. Full article
(This article belongs to the Collection Review Papers in Microstructures of Alloys)
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17 pages, 7824 KiB  
Article
A Study of Song Dynasty Polychrome Statue-Making Techniques and Materials in the Sage Mother Hall of the Jinci Temple, Shanxi, China
by Jizhang Li, Jianrui Zha, Xiaoxuan Pan, Tao Zhao, Jinfang Li and Hong Guo
Crystals 2022, 12(7), 1003; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071003 - 19 Jul 2022
Cited by 1 | Viewed by 1729
Abstract
The polychrome statues of the Sage Mother Hall at the Jinci Temple in Taiyuan city are recognized as one of the three masterpieces of the Jinci Temple. They are also regarded as an outstanding representative of ancient Chinese temple statues. These statues possess [...] Read more.
The polychrome statues of the Sage Mother Hall at the Jinci Temple in Taiyuan city are recognized as one of the three masterpieces of the Jinci Temple. They are also regarded as an outstanding representative of ancient Chinese temple statues. These statues possess great historical, artistic, scientific, cultural and social values, and they are an important physical material for the study of ancient Chinese history, culture, religion, politics and economy, as well as science and technology. The internal structure, plaster layer samples and surface pigments of the polychrome statues of the Sage Mother Hall were analyzed by optical microscope (OM) scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM–EDS), X-ray powder diffraction (XRD), Raman spectroscopy (Raman), X-radiography and other analytical methods in order to gain an understanding of the production process and pigment composition of the polychrome statues of the Sage Mother Hall. According to the findings, the following steps were taken during the production of the polychrome statues that decorate the Sage Mother Hall at Jinci Temple: building a wooden skeleton, fixing the skeleton with rivets or twine, shaping the clay form with coarse clay, shaping the appearance with fine clay, refining the molded appearance, and white substrate layer painting. The majority of the pigments are inorganic mineral pigments: the red pigments include cinnabar and minium; the blue pigments include ultramarine; the green pigments include lavendulan; the yellow pigments include yellow ochre; the black pigments include carbon black; and the white pigments and substrate layers include white lead and lead sulfate. Some of the pigment layers can be seen in multiple layers, which indicates that over the history of the painted statues of the Sage Mother Hall, they have been subject to a series of repainting, with the more recent repainting time perhaps having taken place during the late Qing Dynasty and the following time period. Full article
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)
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14 pages, 947 KiB  
Article
Parameters Optimization of Intermediate Band Solar Cells: Cases of PbTe/CdTe, PbSe/ZnTe and InN/GaN Quantum Dots
by Laura M. Pérez, Asmae EL Aouami, Kawtar Feddi, Vittorianna Tasco, Abdellatif Ben Abdellah, Francis Dujardin, Maykel Courel, Javier A. Riquelme, David Laroze and EL Mustapha Feddi
Crystals 2022, 12(7), 1002; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071002 - 19 Jul 2022
Cited by 4 | Viewed by 1465
Abstract
Photovoltaic cells, based on quantum dots implementation in the intrinsic region, are one of the most widely studied concepts nowadays to obtain a high solar conversion efficiency. The challenge in this third generation of solar cells is to find a good combination of [...] Read more.
Photovoltaic cells, based on quantum dots implementation in the intrinsic region, are one of the most widely studied concepts nowadays to obtain a high solar conversion efficiency. The challenge in this third generation of solar cells is to find a good combination of materials that allows obtaining higher efficiency with low cost. In this study, we consider a juxtaposition of two kinds of quantum dots (dot/barrier) inside the I region of the PIN junction: the first combination of semiconductors includes the two configurations, PbTe/CdTe and PbSe/ZnTe, and the second combination is InN/GaN. Thus the intermediate band can be tailored by controlling the size of the dots and the inter-dot distances. The principal interest of this investigation is to determine the optimized parameters (the dot size and the inter-dot distance), leading to obtain a better solar cell efficiency. Intermediate bands, their positions, and their widths, are determined using 3D confined particles (electron and hole). Their energy levels are determined by solving the Schrödinger equation and solving the well-known dispersion relation in the Kronig–Penney model. Full article
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13 pages, 5876 KiB  
Article
Effect of Austempering on Mechanical Properties of Nb/V Microalloyed Bainitic Bearing Steel
by Yanhui Wang, Baisong Liu, Qiang Pan, Jing Zhao, Xiaojia Zhao, Huaqiang Sun, Dong Xu and Zhinan Yang
Crystals 2022, 12(7), 1001; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071001 - 19 Jul 2022
Cited by 7 | Viewed by 1429
Abstract
In this study, a multi-element microalloyed GCr15Si1MoNbV bainitic bearing steel was designed by adding trace amounts of Nb and V. The bainite/martensite/retained austenite/undissolved carbide multiphase bearing steel with a short heat-treated cycle and remarkable comprehensive mechanical properties was prepared via low-temperature austempering, which [...] Read more.
In this study, a multi-element microalloyed GCr15Si1MoNbV bainitic bearing steel was designed by adding trace amounts of Nb and V. The bainite/martensite/retained austenite/undissolved carbide multiphase bearing steel with a short heat-treated cycle and remarkable comprehensive mechanical properties was prepared via low-temperature austempering, which was compared with a traditional quenched and tempered martensitic microstructure. The results showed that the comprehensive mechanical properties of the low-temperature bainitic microstructure of the Nb/V microalloyed bearing steel were better than those of a traditional tempered martensitic microstructure. In addition, as the isothermal temperature increased, the impact toughness of experimental steel was significantly improved, and the hardness decreased slightly. The tensile strength was improved with the increase in isothermal time. As the isothermal temperature increased, the bainite content of the experimental steel rose, and the stability of the retained austenite enhanced due to more carbon atoms being partitioned into it. The research work in this paper made a preliminary exploration for the application of Nb/V microalloyed bainitic bearing steel in the bearing field and provided some basic data for reference. Full article
(This article belongs to the Special Issue Advances in High Strength Steels)
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20 pages, 6647 KiB  
Review
Steroid-Based Liquid Crystalline Polymers: Responsive and Biocompatible Materials of the Future
by Bartlomiej Czubak, Nicholas J. Warren and Mamatha Nagaraj
Crystals 2022, 12(7), 1000; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12071000 - 19 Jul 2022
Cited by 3 | Viewed by 2275
Abstract
Steroid-based liquid crystal polymers and co-polymers have come a long way, with new and significant advances being made every year. This paper reviews some of the recent key developments in steroid-based liquid crystal polymers and co-polymers. It covers the structure–property relationship between cholesterol [...] Read more.
Steroid-based liquid crystal polymers and co-polymers have come a long way, with new and significant advances being made every year. This paper reviews some of the recent key developments in steroid-based liquid crystal polymers and co-polymers. It covers the structure–property relationship between cholesterol and sterol-based compounds and their corresponding polymers, and the influence of chemical structure and synthesis conditions on the liquid crystalline behaviour. An overview of the nature of self-assembly of these materials in solvents and through polymerisation is given. The role of liquid crystalline properties in the applications of these materials, in the creation of nano-objects, drug delivery and biomedicine and photonic and electronic devices, is discussed. Full article
(This article belongs to the Special Issue State-of-the-Art Liquid Crystals Research in UK)
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10 pages, 3217 KiB  
Article
TSFZ Growth of Eu-Substituted Large-Size LSCO Crystals
by Olesia Voloshyna, Vitaliy V. Romaka, Koushik Karmakar, Silvia Seiro, Andrey Maljuk and Bernd Büchner
Crystals 2022, 12(7), 998; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070998 - 18 Jul 2022
Cited by 1 | Viewed by 1779
Abstract
The travelling solvent floating zone (TSFZ) growth of Eu-substituted LSCO (La1.81−xEuxSr0.19CuO4, with nominal x = 0 ÷ 0.4) single crystals was systematically explored for the first time. The substitution of La with Eu considerably decreased [...] Read more.
The travelling solvent floating zone (TSFZ) growth of Eu-substituted LSCO (La1.81−xEuxSr0.19CuO4, with nominal x = 0 ÷ 0.4) single crystals was systematically explored for the first time. The substitution of La with Eu considerably decreased the decomposition temperature. Optimal growth parameters were found to be: oxygen pressure 9.0–9.5 bars; Eu-free CuO-poor solvent (66 mol% CuO) with a molar ratio of La2O3:SrCO3:CuO = 4:4.5:16.5 and growth rate 0.6 mm/hour. The obtained single crystals were characterized with optical polarized microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy analysis. The solubility of Eu in LSCO appeared to be limited to x~0.36–0.38 under the used conditions. The substitution of La3+ with smaller Eu3+ ions led to a structural transition from tetragonal with space group I4/mmm for La1.81Sr0.19CuO4 (x = 0) to orthorhombic with space group Fmmm for La1.81−xSr0.19EuxCuO4 (x = 0.2, 0.3, 0.4), and to a substantial shrinking of the c-axis from 13.2446 Å (x = 0.0) to 13.1257 Å (x = 0.4). Such structural changes were accompanied by a dramatic decrease in the superconducting critical temperature, Tc, from 29.5 K for x = 0 to 13.8 K for 0.2. For x ≥ 0.3, no superconductivity was detected down to 4 K. Full article
(This article belongs to the Special Issue Solution-Based Processes in Semiconductors and Electronic Devices)
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7 pages, 5082 KiB  
Article
Trapping Capability of Small Vacancy Clusters in the α-Zr Doped with Alloying Elements: A First-Principles Study
by Rongjian Pan, Aitao Tang, Jiantao Qin, Tianyuan Xin, Xiaoyong Wu, Bang Wen and Lu Wu
Crystals 2022, 12(7), 997; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070997 - 18 Jul 2022
Viewed by 1019
Abstract
Zirconium alloys are subjected to a fast neutron flux in nuclear reactors, inducing the creation of a large number of point defects, both vacancy and self-interstitial. These point defects then diffuse and can be trapped by their different sinks or can cluster to [...] Read more.
Zirconium alloys are subjected to a fast neutron flux in nuclear reactors, inducing the creation of a large number of point defects, both vacancy and self-interstitial. These point defects then diffuse and can be trapped by their different sinks or can cluster to form larger defects, such as vacancy and interstitial clusters. In this work, the trapping capability of small-vacancy clusters (two/three vacancies, V2/V3) in the α-Zr doped with alloying elements (Sn, Fe, Cr, and Nb) has been investigated by first-principle calculations. Calculation results show that for the supercells of α-Zr containing 142-zirconium atoms with the two-vacancy cluster, alloying elements of Sn and Nb in the second vacant site (V2) and Cr in the first vacant site (V1) are more easily trapped by two vacancies, respectively. However, the two sites are both captured more easily by two vacancies for Fe in the supercells of α-Zr containing 142-zirconium atoms inside due to the similar value of the Fermi level. For the supercells of α-Zr containing 141-zirconium atoms with the three-vacancy cluster, the alloying element of Sn in the third vacant site (V’3), Fe in the first vacant site (V’1), and Cr and Nb in the second vacant site (V’2) are more easily trapped by three vacancies, respectively. Full article
(This article belongs to the Special Issue Advances in Zr-Based Alloys)
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9 pages, 12101 KiB  
Article
Effects of ESMT on Microstructure and Mechanical Properties of Al-8Zn-2Mg-1.5Cu-0.15Sc-0.15Zr Cast Alloy in Squeeze Casting Process
by Yongtao Xu, Zhifeng Zhang, Purui Zhao, Zhihua Gao, Yuelong Bai and Weimin Mao
Crystals 2022, 12(7), 996; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070996 - 18 Jul 2022
Cited by 3 | Viewed by 1276
Abstract
Al-8Zn-2Mg-1.5Cu-0.15Sc-0.15Zr alloy with high-strength performance as well as good castability has been developed. In this study, effects of electromagnetic stirring melt treatment (ESMT) on microstructure and mechanical properties of the alloy in the squeeze casting process were investigated. The results show that solidification [...] Read more.
Al-8Zn-2Mg-1.5Cu-0.15Sc-0.15Zr alloy with high-strength performance as well as good castability has been developed. In this study, effects of electromagnetic stirring melt treatment (ESMT) on microstructure and mechanical properties of the alloy in the squeeze casting process were investigated. The results show that solidification structure and mechanical properties are significantly improved by ESMT; compared with the conventional squeeze casting, the average grain size decreases from 112 μm without ESMT to 53 μm with ESMT. Meanwhile coarse primary Al3(Sc, Zr) particles unavoidably occurred in cases without ESMT disappear, and segregation degree of the main elements of Zn, Mg, Cu are greatly alleviated; the tensile strength increases from 590 MPa to 610 MPa, and the elongation increases from 9% to 11%. The structure refinement and homogenization should owe to uniform temperature and composition distribution by ESMT under squeeze casting with rapid solidification. Full article
(This article belongs to the Section Hybrid and Composite Crystalline Materials)
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16 pages, 3517 KiB  
Article
Nanomechanical Characterization of Enzyme Induced Carbonate Precipitates
by Vinay Krishnan, Hamed Khodadadi Tirkolaei, Maryam Kazembeyki, Leon A. van Paassen, Christian G. Hoover, Jong Seto and Edward Kavazanjian, Jr.
Crystals 2022, 12(7), 995; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070995 - 17 Jul 2022
Cited by 1 | Viewed by 2717
Abstract
The mechanical properties of calcium carbonate minerals formed by enzyme-induced carbonate precipitation (EICP) were studied using nanoindentation. Two types of precipitates were considered: (i) a “baseline” precipitate, synthesized via urea hydrolysis in an aqueous solution of urease enzyme, urea, and calcium chloride; and [...] Read more.
The mechanical properties of calcium carbonate minerals formed by enzyme-induced carbonate precipitation (EICP) were studied using nanoindentation. Two types of precipitates were considered: (i) a “baseline” precipitate, synthesized via urea hydrolysis in an aqueous solution of urease enzyme, urea, and calcium chloride; and (ii) a “modified” precipitate, synthesized from a similar solution, but with the inclusion of nonfat dry milk. While both precipitates predominantly comprised calcite, X-ray diffraction and Raman spectroscopy indicated broader peaks in the modified precipitate, implying differences in the crystal structure of the two precipitates. Both precipitates were polycrystalline and had a higher average indentation hardness (H) and a lower indentation modulus (M) compared with the values for single calcite crystals reported in the literature. The ductility of the precipitates was quantified by the ratio M/H. The modified precipitate had a higher average M/H, implying greater ductility. The increased ductility of the modified precipitate results in higher resistance to crack propagation. In sands biocemented using the modified EICP solution, the increased ductility of the precipitate, in addition to preferential precipitation at interparticle contacts, may contribute to relatively high unconfined compressive strengths at low carbonate contents. Full article
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9 pages, 2597 KiB  
Article
Crystal Growth of RuS2 Using a Chemical Vapor Transport Technique and Its Properties
by Refka Sai, Ouri Gorochov, Eman A. Alghamdi and Hatem Ezzaouia
Crystals 2022, 12(7), 994; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070994 - 17 Jul 2022
Cited by 2 | Viewed by 1273
Abstract
In this work, we study the effect of increasing temperature on the structure parameters (lattice, sulfur–sulfur distance, and ruthenium–sulfur distance) and the energy gap of RuS2. However, it was very challenging to obtain a sample of RuS2 due to many [...] Read more.
In this work, we study the effect of increasing temperature on the structure parameters (lattice, sulfur–sulfur distance, and ruthenium–sulfur distance) and the energy gap of RuS2. However, it was very challenging to obtain a sample of RuS2 due to many factors, some of which are discussed in the introduction. To prepare the crystal growth of RuS2, we have used the chemical vapor transport technique. The crystals obtained show a pyrite structure, of which we studied its crystallographic structure, including the structure of crystals in surface (100). The sample was then characterized by X-ray diffraction and by microprobe analysis. We determine the relationship between the energy gap and the sulfur–sulfur distance. We analyzed the S-S bond compared with the S2 molecule. Full article
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13 pages, 7239 KiB  
Article
A Study on the Healing Performance of Solid Capsules for Crack Self-Healing of Cementitious Composites
by Yong Jic Kim, Yun Wang Choi and Sung-Rok Oh
Crystals 2022, 12(7), 993; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070993 - 17 Jul 2022
Cited by 1 | Viewed by 1324
Abstract
The purpose of this study is to investigate the healing performance of solid capsules made of cement as a basis for manufacturing self-healing capsules that can heal cracks in cementitious composites. The solid capsules were mixed with 5%, 10%, and 15% concentrations on [...] Read more.
The purpose of this study is to investigate the healing performance of solid capsules made of cement as a basis for manufacturing self-healing capsules that can heal cracks in cementitious composites. The solid capsules were mixed with 5%, 10%, and 15% concentrations on the cement. The self-healing performance of cementitious composites with solid capsules was investigated through three evaluations. First, the mechanical strength-healing performance was evaluated through a re-loading test. Second, the durability-healing performance was evaluated through a permeability test. Finally, the crack-healing performance was examined by observing the crack widths. Through evaluation of the healing performance of the solid capsules, the healing performance of the compressive strength was found to be high when the capsule proportion was 10% and its size was within the range of 300 μm to 850 μm. Furthermore, the splitting tensile strength showed a high healing performance when the capsule proportion mixed was 15% and its size was 850 μm. In the case of the permeability test, a capsule size of 850 μm showed a healing effect greater than 95%. Cracks with a width of up to 200 μm tended to heal using capsules with a size of 600 μm to 850 μm. Full article
(This article belongs to the Special Issue Advances in Cement-Based Composites and Novel Construction Products)
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10 pages, 7838 KiB  
Communication
Performance Analysis of DAST Material-Assisted Photonic-Crystal-Based Electrical Tunable Optical Filter
by Amit Kumar Goyal, Ajay Kumar and Yehia Massoud
Crystals 2022, 12(7), 992; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070992 - 17 Jul 2022
Cited by 14 | Viewed by 1575
Abstract
In this paper, a 4-N,N-dimethylamino-4-N-methyl-stilbazolium tosylate (DAST) material assisted one-dimensional photonic-crystal-based (1D-PhC) tunable optical filter is presented. The design comprises a bilayer 1D-PhC structure having DAST as an electro-optic material. The device parameters are [...] Read more.
In this paper, a 4-N,N-dimethylamino-4-N-methyl-stilbazolium tosylate (DAST) material assisted one-dimensional photonic-crystal-based (1D-PhC) tunable optical filter is presented. The design comprises a bilayer 1D-PhC structure having DAST as an electro-optic material. The device parameters are configured to filter out the 632.8 nm wavelength from the reflection spectrum. The analysis shows that by illuminating the device with poly-chromatic light at an incident angle of 45.07°, the filtered wavelength exhibits transmission maxima having FWHM of less than 1nm. The analytical results also demonstrate the post fabrication 60 nm electrical tuning of the filtered wavelength by using only ±5 V applied potential. The structure also exhibits a very stable filter response up to 40% variations in optical thickness. Thus, the proposed design possesses the advantage in terms of low voltage wavelength tuning, stable response, easy fabrication and integration capability in integrated circuits. Full article
(This article belongs to the Special Issue Recent Advances in Photonic Crystal and Optical Devices)
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10 pages, 2888 KiB  
Article
Effect of κ Carbides on Deformation Behavior of Fe-27Mn-10Al-1C Low Density Steel
by Siyuan Li, Dazhao Li, Haitao Lu, Pengfei Cao and Ruofei Xie
Crystals 2022, 12(7), 991; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070991 - 17 Jul 2022
Cited by 5 | Viewed by 1681
Abstract
Fe-Mn-Al-C steel, which is a potential lightweight material for automobiles, has a variety of microstructures and good mechanical properties. The effect of κ carbides on the mechanical properties and strain hardening rate of Fe-27Mn-10Al-1C (wt.%) low density steel was studied by short-time heat [...] Read more.
Fe-Mn-Al-C steel, which is a potential lightweight material for automobiles, has a variety of microstructures and good mechanical properties. The effect of κ carbides on the mechanical properties and strain hardening rate of Fe-27Mn-10Al-1C (wt.%) low density steel was studied by short-time heat treatment to control the precipitation behavior of κ carbides. Quenched specimens have an excellent combination of strength and plasticity and continuous high strain hardening rate, which is due to the uniform distribution of κ carbides with an average size of 1.6 nm in an austenite matrix. The fracture mode of the sample changed from ductile fracture to cleavage fracture, which was because the aging treatment promoted the precipitation of B2 phases and κ carbides at grain boundaries. The size and volume fraction of nanoscale κ carbides in austenite grains increase with the increase of aging temperature, and the yield strength increases but the density of slip bands decreases, resulting in the gradual decrease of strain hardening rate. Full article
(This article belongs to the Special Issue Structural Changes during Steel Processing)
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12 pages, 3832 KiB  
Article
Investigation of Major Flavonoids from Artemisia argyi as a Potential COVID-19 Drug: Molecular Docking and DFT Calculations
by Yang Lu, Bin Zhang, Ning Wang, Mengshan Li and Ning Xi
Crystals 2022, 12(7), 990; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070990 - 16 Jul 2022
Cited by 5 | Viewed by 1741
Abstract
Flavonoids from natural products are well-identified as potential antiviral agents in the treatment of SARS-CoV-2 (COVID-19) infection and related diseases. However, some major species of flavonoids from Chinese traditional folk medicine, such as of Artemisia argyi (A. argyi), have not been [...] Read more.
Flavonoids from natural products are well-identified as potential antiviral agents in the treatment of SARS-CoV-2 (COVID-19) infection and related diseases. However, some major species of flavonoids from Chinese traditional folk medicine, such as of Artemisia argyi (A. argyi), have not been evaluated yet. Here, we choose five major flavonoids obtained from A. argyi, namely, Jaceosidin (1), Eupatilin (2), Apigenin (3), Eupafolin (4), and 5,6-Dihydroxy-7,3′,4′-trimethoxyflavone (5), compared to the well-studied Baicalein (6), as potential inhibitors analogs for COVID-19 by computational modeling strategies. The frontier molecular orbitals (FMOs), chemical reactivity descriptors, and electrostatic surface potential (ESP) were performed by density functional theory (DFT) calculations. Additionally, these flavonoids were docked on the main protease (PDB: 6LU7) of SARS-CoV-2 to evaluate the binding affinities. Computational analysis predicted that all of these compounds show a high affinity and might serve as potential inhibitors to SARS-CoV-2, among which compound (5) exhibits the least binding energy (−155.226 kcal/mol). The high binding affinity could be enhanced by increasing the electron repulsion due to the valence shell electron pair repulsion model (VSEPR). Consequently, the major flavonoids in Artemisia argyi have a significant ability to reduce the deterioration of COVID-19 in the terms of DFT calculations and molecular docking. Full article
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9 pages, 2683 KiB  
Article
Fully Relaxed, Crack-Free AlGaN with upto 50% Al Composition Grown on Porous GaN Pseudo-Substrate
by Nirupam Hatui, Henry Collins, Emmanuel Kayede, Shubhra S. Pasayat, Weiyi Li, Stacia Keller and Umesh K. Mishra
Crystals 2022, 12(7), 989; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070989 - 16 Jul 2022
Cited by 2 | Viewed by 2120
Abstract
Fully relaxed, crack free, smooth AlxGa1−xN layers with up to 50% Al composition were demonstrated on pseudo-substrates composed of dense arrays of 10 × 10 µm2 compliant porous GaN-on-porous-GaN tiles. The AlGaN layers were grown in steps for [...] Read more.
Fully relaxed, crack free, smooth AlxGa1−xN layers with up to 50% Al composition were demonstrated on pseudo-substrates composed of dense arrays of 10 × 10 µm2 compliant porous GaN-on-porous-GaN tiles. The AlGaN layers were grown in steps for a total of 1.3 µm. The growth conditions necessary to demonstrate high quality films at higher Al compositions also suppressed any sidewall growth. Full article
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14 pages, 9079 KiB  
Article
In Vitro Physical Characterizations and Docking Studies on Carvedilol Nanocrystals
by Jamal Moideen Muthu Mohamed, Ali Alqahtani, Farid Menaa, Saminathan Kayarohanam, Adel Al Fatease, Taha Alqahtani, Ali Alamri, Mohamed El-Sherbiny, Sundarapandian Ramkanth and Ashok Kumar Janakiraman
Crystals 2022, 12(7), 988; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070988 - 16 Jul 2022
Cited by 10 | Viewed by 1547
Abstract
The major goal of this investigation was to prepare carvedilol nanocrystals (CRL-NCs) for better solubility, stability, and bioavailability. Using polyvinyl pyrolidine K-30 (PVP) and sodium dodecyl sulphate (SDS) as stabilisers, CRL-NCs were effectively synthesised by emulsion-diffusion, followed by the high-pressure homogenization (HPH) method. [...] Read more.
The major goal of this investigation was to prepare carvedilol nanocrystals (CRL-NCs) for better solubility, stability, and bioavailability. Using polyvinyl pyrolidine K-30 (PVP) and sodium dodecyl sulphate (SDS) as stabilisers, CRL-NCs were effectively synthesised by emulsion-diffusion, followed by the high-pressure homogenization (HPH) method. The AL classes of phase solubility curves with ideal complexes produced with stabilisers were estimated by thermodynamic parameters. The docking study was performed with the active site of a β-1 adrenoreceptor protein, and the CRLs docking score was revealed as −23.481 Kcal/mol−1. At 25 and 37 °C, the optimum interaction constant was determined for PVP (144 and 176 M−1) and SDS (102 and 121 M−1). The average particle size (PS) of the produced stable CRL-NCs is 58 nm, with a zeta potential of −27.2 ± 2.29 mV, a poly dispersibility index of 0.181 ± 0.012, a percentage yield of 78.7 ± 3.41, drug content of 96.81 ± 3.64%, and entrapment efficiency of 83.61 ± 1.80%. The morphological data also reveals that the CRL-NCs were nearly sphere shaped, with distinct and smooth surfaces. CRL-NCs were studied using X-ray diffraction (XRD), fourier transform infrared (FT-IR) spectroscopy, and differential scanning calorimetry (DSC), and the results show no chemical structural alterations, even when PS was reduced. NCs accelerate their in vitro dissolution release rate by about three times faster than CRL-MCs (microcrystals). When kept at 4 °C, the CRL-NCs exhibit good physical stability for six months. As a result, the CRL-NCs created via emulsion-diffusion followed by HPH with stabilisers can be used to increase the solubility, stability, and bioavailability of poorly soluble or lipophilic drugs. Full article
(This article belongs to the Special Issue Computational Research into Pharmaceutical Crystals)
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11 pages, 2599 KiB  
Article
Molecular Dynamics Simulation of the Crystallization Behavior of Octadecane on a Homogeneous Nucleus
by Stefanie Tafelmeier and Stefan Hiebler
Crystals 2022, 12(7), 987; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070987 - 15 Jul 2022
Cited by 3 | Viewed by 2247
Abstract
Latent heat storages have the ability to contribute to a more sustainable energy supply network. However, phase change materials (PCM) used for latent heat storages often show supercooling. This phenomenon takes place whenever the PCM begins crystallizing below the freezing point and is [...] Read more.
Latent heat storages have the ability to contribute to a more sustainable energy supply network. However, phase change materials (PCM) used for latent heat storages often show supercooling. This phenomenon takes place whenever the PCM begins crystallizing below the freezing point and is one of the biggest drawbacks holding back the widespread use of PCM. Nucleation agents (NA) can be used to avoid the supercooling, yet the choice of an effective NA is not straightforward. In this work, molecular dynamics (MD) simulation was tested in order to simulate the crystallization of Octadecane on a NA. The simulation results include density, phase change temperature and enthalpy as well as the crystal structure and lie in good agreement with literature values and the authors’ own experimental data. Further simulations of the crystallization process on different surfaces of homogeneous nuclei acting as a NA were performed. The results reflect the hypothesis that liquid molecules start crystallizing easier on surfaces exposing the whole chain side rather than the chain ends. With the result, that the choice of parameters for the MD simulation represent the Octadecane system reliably and further studies can be performed including heterogeneous NA. Full article
(This article belongs to the Special Issue Crystals for Thermal Energy Storage)
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11 pages, 3665 KiB  
Article
Growth and Spectroscopy of Yb:YMgB5O10 Crystal
by Konstantin N. Gorbachenya, Anatol S. Yasukevich, Andrey I. Lazarchuk, Victor E. Kisel, Nikolay V. Kuleshov, Elena A. Volkova, Victor V. Maltsev, Elizaveta V. Koporulina, Vasiliy O. Yapaskurt, Nikolai N. Kuzmin, Dmitry A. Ksenofontov, Diana D. Mitina and Anna I. Jiliaeva
Crystals 2022, 12(7), 986; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070986 - 15 Jul 2022
Cited by 2 | Viewed by 1505
Abstract
A transparent Yb:YMgB5O10 single crystal with dimensions up to 25 × 23 × 25 mm and weight 10.337 g was grown using a high-temperature solution growth on dipped seeds technique with a K2Mo3O10 solvent. The [...] Read more.
A transparent Yb:YMgB5O10 single crystal with dimensions up to 25 × 23 × 25 mm and weight 10.337 g was grown using a high-temperature solution growth on dipped seeds technique with a K2Mo3O10 solvent. The Yb3+ concentration was calculated to be 4.7 at.% (NYb = 3.71 × 1020 atoms/cm3) with a distribution coefficient Kd of 0.59. The grown crystal was characterized by means of PXRD, TGA-DSC and ATR-FTIR techniques. The spectroscopic characteristics of the Yb:YMgB5O10 crystal were demonstrated. Absorption cross-section spectra were produced. The luminescence spectra of the Yb:YMgB5O10 crystal were measured in the spectral range of 950–1100 nm. The luminescence kinetics of the 2F5/2 energy level were investigated and the lifetime was determined. Full article
(This article belongs to the Special Issue Structural and Spectroscopic Studies of Rare Earth Doped Crystals)
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10 pages, 6126 KiB  
Article
Large-Scale Synthesis h-BN Films on Copper-Nickel Alloy by Atmospheric Pressure Chemical Vapor Deposition
by Yuhan Feng, Yumin Zhang, Jipeng Liu, Ye Zhang and Yongshuai Xie
Crystals 2022, 12(7), 985; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070985 - 15 Jul 2022
Cited by 2 | Viewed by 1417
Abstract
Due to its high thermal and chemical stability, excellent dielectric properties, unique optical properties, corrosion resistance, and oxidation resistance, the two-dimensional hexagonal boron nitride (h-BN) is often used in a thermal conductor protective layer in deep ultraviolet light-emitting detector fields. However, due to [...] Read more.
Due to its high thermal and chemical stability, excellent dielectric properties, unique optical properties, corrosion resistance, and oxidation resistance, the two-dimensional hexagonal boron nitride (h-BN) is often used in a thermal conductor protective layer in deep ultraviolet light-emitting detector fields. However, due to the complicated growth conditions of h-BN, it is often necessary to prepare h-BN by the CVD method in a high vacuum environment, which is limited to a certain extent in terms of film size and production cost. In order to solve this problem, we proposed a method to prepare h-BN thin films by atmospheric CVD (APCVD). This method does not need a vacuum environment, which reduces energy consumption and cost, and makes the operation simpler and the experimental environment safer. The preparation of high-quality h-BN film was carried out using a Cu-Ni alloy as the growth substrate. The growth process of h-BN film was studied, and the influence of growth parameters on the structure of the h-BN film was explored. The morphological features and elemental composition pairs of the samples were characterized and analyzed, which confirmed that the high-quality h-BN film could be successfully grown on the Cu-Ni alloy substrate by APCVD. The UV detection device prepared by using the prepared h-BN film as the photoresponse material had good photoresponse characteristics and performance stability. It provides a new idea for the low-cost preparation of large-scale h-BN. Full article
(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)
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