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Crystals, Volume 12, Issue 4 (April 2022) – 129 articles

Cover Story (view full-size image): Due to the increasing demands on the tailored properties of CLECs in terms of enzymatic activity, as well as mechanical stability, an elucidation of the relationships between the structure and the resulting properties is of particular interest. For this purpose, wild-type and genetically modified model proteins were crystallized, cross-linked, and mechanically examined. Then, based on the respective crystal structure, a mathematical model was developed and used to explain the mechanically investigated relationships, such as the anisotropic crystal behavior and the influence of a linker or mutation on the micromechanical properties. This could be helpful for the tailor-made production of CLECs. View this paper
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Article
Evaluation of the Structural Deviation of Cu/Cu2O Nanocomposite Using the X-ray Diffraction Analysis Methods
Crystals 2022, 12(4), 566; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040566 - 18 Apr 2022
Viewed by 455
Abstract
We successfully synthesized Cu/Cu2O nanocomposites using the wet chemical synthesis method. All X-ray diffraction (XRD), Reference Intensity Ratio (RIR), and Rietveld refinement methods confirmed that the compounds Cu and Cu2O are free of impurities. Scanning Electron Microscope (SEM) and [...] Read more.
We successfully synthesized Cu/Cu2O nanocomposites using the wet chemical synthesis method. All X-ray diffraction (XRD), Reference Intensity Ratio (RIR), and Rietveld refinement methods confirmed that the compounds Cu and Cu2O are free of impurities. Scanning Electron Microscope (SEM) and Transmission electron microscopy (TEM) images show the morphology and interactions of Cu and Cu2O in the structure. The formation mechanism is also explained by five stages: precursor, nucleation, growth, aging, and reduction. The changes in crystallization parameters under variations in reaction temperature (Tv) and stirring speed (Sv) were confirmed by agreement with the XRD database. The lattice constant in the crystal of nanocomposite increases with rising temperature in the reaction, leading to unit cell expansion, while increasing the stirring—rate leads to a random size distribution of the lattice parameter. Due to the imperfect growth of the crystal, the induced crystallite size was calculated using the Williamson-Hall model, and the precise lattice parameter values were calculated using the Nelson-Riley function. Full article
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Article
Cracking Behavior, Microstructure and Properties of Selective Laser Melted Al-Mn-Mg-Sc-Zr Alloy
Crystals 2022, 12(4), 565; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040565 - 18 Apr 2022
Viewed by 445
Abstract
In this paper, the cracking of Al-Mn-Mg-Sc-Zr alloys prepared by selective laser melting (SLM) was comprehensively explored and the influence of process parameters on the generation and propagation of cracks was deeply studied. It was found that the higher laser power and volume [...] Read more.
In this paper, the cracking of Al-Mn-Mg-Sc-Zr alloys prepared by selective laser melting (SLM) was comprehensively explored and the influence of process parameters on the generation and propagation of cracks was deeply studied. It was found that the higher laser power and volume energy density will lead to a decrease in the relative density of the material. The lower laser power or volume energy density will lead to cracking of the alloy. The microstructure analysis indicated that plenty of manganese-rich second phases precipitated at the bottom of the melt pool, which increased the tendency of cracking occurred at the bottom of the melt pool. Through the optimization of the process parameters, the SLM forming process parameters of the Al-5.22Mn-1.16Mg-0.81Sc-0.46Zr alloy are successfully obtained, and the crack-free tensile samples are prepared. The microstructure and mechanical properties of the as-deposited aluminum-manganese alloy is analyzed. The bottom and inside of the melt pool are equiaxed grains. The size of the equiaxial grains at the bottom of the melt pool is less than 2 μm, and the coarse equiaxial grains inside the melt pool are approximately 5 μm. As-deposited alloy has a room temperature tensile strength of 455.2 ± 0.7 MPa and elongation of 15.4 ± 0.3%. This study provides guidance for selective laser melting forming of high-strength aluminum-manganese alloy parts, and promotes the industrial production of high-strength aluminum alloy near net forming complex parts. Full article
(This article belongs to the Special Issue Design and Development of Al Alloys and Composites)
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Article
The Effect of Annealing on the Optoelectronic Properties and Energy State of Amorphous Pyrochlore Y2Ti2O7 Thin Layers by Sol–Gel Synthesis
Crystals 2022, 12(4), 564; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040564 - 18 Apr 2022
Viewed by 447
Abstract
Pyrochlore titanate (Y2Ti2O7) is a promising material for a wide range of applications in optoelectronics and photocatalysis due to its advantageous chemical, mechanical, and optical properties. To enhance its potential for such uses, however, a high-quality and [...] Read more.
Pyrochlore titanate (Y2Ti2O7) is a promising material for a wide range of applications in optoelectronics and photocatalysis due to its advantageous chemical, mechanical, and optical properties. To enhance its potential for such uses, however, a high-quality and scalable synthesis method is required. We here investigate the crystallization of sol–gel produced Y2Ti2O7 layers. We observe a transition of the amorphous pyrochlore phase at annealing temperatures below 700 °C. The transmittances of the Y2Ti2O7 thin layers annealed at 400 to 700 °C are approximately 92.3%. The refractive indices and packing densities of Y2Ti2O7 thin layers annealed at 400–700 °C/1 h vary from 1.931 to 1.954 and 0.835 to 0.846, respectively. The optical bandgap energies of Y2Ti2O7 thin layers annealed at 400–700 °C/1 h reduce from 4.356 to 4.319 eV because of the Moss–Burstein effect. These good electronic and optical properties make Y2Ti2O7 thin layers a promising host material for many potential applications. Full article
(This article belongs to the Special Issue Advances of Metal Halide Perovskite Devices)
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Article
Effect of Heat Treatment on Mechanical Properties and Fracture Behavior of Al-7.0Si-0.3Mg Alloy at Low Temperature
Crystals 2022, 12(4), 563; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040563 - 17 Apr 2022
Viewed by 471
Abstract
In order to investigate the effect of heat treatment on the mechanical properties of the Al-7.0Si-0.3Mg alloy at 20–60 °C under different heat treatment processes, the tensile mechanical properties of Al-7.0Si-0.3Mg at low temperature after heat treatment were explored. The microstructure of Al-7.0Si-0.3Mg [...] Read more.
In order to investigate the effect of heat treatment on the mechanical properties of the Al-7.0Si-0.3Mg alloy at 20–60 °C under different heat treatment processes, the tensile mechanical properties of Al-7.0Si-0.3Mg at low temperature after heat treatment were explored. The microstructure of Al-7.0Si-0.3Mg was observed by scanning electron microscopy (SEM) and transmission electron microscopy. The results show that the resistance of the dislocation movement in α-Al increased in the low-temperature condition, which is beneficial for the number of Si phase fractures that increase to enhance the tensile strength and weaken the elongation of the Al-7.0Si-0.3Mg alloy. After the solution treatment, the particle size of the Si phase reduced, while the morphology became rounded. In the early stage of aging, a GP region is generated inside the α-Al. With the prolonging of aging time, the acicular β″ phase is formed and then grows into rod-shaped β′. In the overaging stage, β′ eventually grows into flaky β. Due to the different linear expansion coefficients of the α-Al and the Mg2Si phase in the Al-7.0Si-0.3Mg alloy, the α-Al is squeezed by the Mg2Si phase under the effect of low-temperature shrinkage. Full article
(This article belongs to the Special Issue Preparation and Properties of Aluminum Alloy Materials)
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Article
Design and Numerical Study of Argon Gas Diversion System Using Orthogonal Experiment to Reduce Impurities in Large-Sized Casting Silicon
Crystals 2022, 12(4), 562; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040562 - 17 Apr 2022
Viewed by 544
Abstract
To reduce oxygen and carbon impurities while casting silicon, an argon gas diversion system is proposed. A series of two-dimensional global transient numerical simulations are carried out using Fluent software according to the orthogonal experimental design, including heat transfer, convection of silicon melt [...] Read more.
To reduce oxygen and carbon impurities while casting silicon, an argon gas diversion system is proposed. A series of two-dimensional global transient numerical simulations are carried out using Fluent software according to the orthogonal experimental design, including heat transfer, convection of silicon melt and argon gas, and the fully coupling transport of impurities. The numerical results show that when the distance between the outer tube outlet and the cover is 10 mm, the backflow is inhibited by lateral outflow, thus the generation of CO is suppressed and the penetration of impurities into the silicon melt is decreased. The larger the flow rate, the more obvious the effect is. When the outer tube outlet is far from the cover, the effect of removing impurities is no longer significant. In addition, too large or too small an inner tube flow rate is not conducive to impurity reduction. The optimal parameter combination of outer tube flow rate, inner tube flow rate, and the distance between outer tube outlet and the cover are determined by the orthogonal experiment. Compared with the original furnace, the average concentration of oxygen and carbon in casting silicon ingots could be decreased by 7.4% and 59.9%, respectively, by using the optimized argon gas diversion system. Full article
(This article belongs to the Special Issue Heat and Mass Transfer Modeling in Crystal Growth)
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Editorial
Time-Resolved Crystallography
Crystals 2022, 12(4), 561; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040561 - 16 Apr 2022
Viewed by 524
Abstract
This Special Issue on ‘Time-Resolved Crystallography’ is a collection of eight original articles providing interesting results that give insight into the processes involved in generating and analysing time-resolved data [...] Full article
(This article belongs to the Special Issue Time Resolved Crystallography)
Article
The Local Exploration of Magnetic Field Effects in Semiconductors
Crystals 2022, 12(4), 560; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040560 - 16 Apr 2022
Viewed by 516
Abstract
This study reports on the local exploration of magnetic field effects in semiconductors, including silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (InP) using the time differential perturbed angular correlation (TDPAC) technique. TDPAC measurements were carried out under external magnetic fields [...] Read more.
This study reports on the local exploration of magnetic field effects in semiconductors, including silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (InP) using the time differential perturbed angular correlation (TDPAC) technique. TDPAC measurements were carried out under external magnetic fields with strengths of 0.48 T and 2.1 T at room temperature, and 77 K following the implantation of 111In (111Cd) probes. Defects caused by ion implantation could be easily removed by thermal annealing at an appropriate temperature. The agreement between the measured Larmor frequencies and the theoretical values confirms that almost no intrinsic point defects are present in the semiconductors. At low temperatures, an electric interaction sets in. It stems from the electron capture after-effect. In the case of germanium and silicon, this effect is well visible. It is associated with a double charge state of the defect ion. No such effects arise in GaAs and InP where Cd contributes only a single electronic defect state. The Larmor frequencies correspond to the external magnetic field also at low temperatures. Full article
(This article belongs to the Special Issue Radioactive Isotopes Based Materials Characterization)
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Article
I-Shaped Metamaterial Using SRR for Multi-Band Wireless Communication
Crystals 2022, 12(4), 559; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040559 - 16 Apr 2022
Viewed by 427
Abstract
A novel I-shaped metamaterial (ISMeTM) using split-ring resonator (SRR) for multi-band wireless communication is presented in this paper. The proposed ISMeTM unit cell structure is designed using the three-square split-ring resonators (SSRRs) and I-shaped copper strip at the center. The size of the [...] Read more.
A novel I-shaped metamaterial (ISMeTM) using split-ring resonator (SRR) for multi-band wireless communication is presented in this paper. The proposed ISMeTM unit cell structure is designed using the three-square split-ring resonators (SSRRs) and I-shaped copper strip at the center. The size of the proposed ISMeTM is 10 × 10 × 1.6 mm3 while utilizing the FR-4 dielectric substrate material. The analysis of various array arrangements, variation in the ring gap, variation in strip length, and the variation in strip width is performed to achieve the optimum results for multi-band operation. The effective permittivity, permeability, and refractive index of the unit cell have been analyzed. The design and simulation of the ISMeTM unit cell and arrays are performed using the Computer Simulation Technology (CST) Studio Suite and MATLAB. The equivalent circuit of the ISMeTM is designed using the Advanced Design System (ADS) software. The split ring’s inner loop’s gap functions as a capacitor, while the metallic ring itself functions as an inductor. Electric resonance is created by the interaction between the split ring and the electric field. The interaction of magnetic fields with metallic loops during EM propagation in the structure causes the magnetic resonance. The variation in dimensions of the structure causes the variation in the inductance and capacitance, which causes the variation in resonant frequency. The proposed design is optimized after several parametric analyses. A comprehensive analysis of 1 × 2, 2 × 2, and 2 × 4 array is also investigated. The results confirm the multi-band operation of the proposed ISMeTM. The proposed ISMeTM is suitable for the multi-band C/X/Ku-band microwave applications. Full article
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Article
Growth and Passive Q-Switching Application of Cr:TiTe3O8 Crystal
Crystals 2022, 12(4), 558; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040558 - 15 Apr 2022
Viewed by 457
Abstract
A Cr4+-doped TiTe3O8 crystal with dimensions up to 21 mm × 21 mm × 11 mm was grown successfully by the top-seeded solution growth method. A high-resolution X-ray diffraction experiment showed that the full width at half-maximum of [...] Read more.
A Cr4+-doped TiTe3O8 crystal with dimensions up to 21 mm × 21 mm × 11 mm was grown successfully by the top-seeded solution growth method. A high-resolution X-ray diffraction experiment showed that the full width at half-maximum of the rocking curve was 41.90″. Energy-dispersive spectrometry (EDS) and X-ray fluorescence spectroscopy (XRF) proved that Cr4+ ions have been doped into the TiTe3O8 crystal with molar percentage of 4.9%. The Cr:TiTe3O8 crystal exhibited an absorption range from 995 to 1565 nm, which is suitable for passive Q switch at 1064 nm. Then, a passive Q-switching solid-state laser operating at 1064 nm was realized using a Cr:TiTe3O8 crystal as the saturable absorber. The maximum laser pulse energy is calculated to be 0.7 μJ, and the maximum peak power reaches 0.7 W. Full article
(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)
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Article
Characterization of Mortars Made with Coal Ashes Identified as a Way Forward to Mitigate Climate Change
Crystals 2022, 12(4), 557; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040557 - 15 Apr 2022
Viewed by 362
Abstract
Portland cement production is an energy-intensive process that releases carbon dioxide into the atmosphere. To reach carbon neutrality by 2050, it would be necessary to implement innovative measures in the cement industry to deliver carbon neutrality. In this respect, it is striking that [...] Read more.
Portland cement production is an energy-intensive process that releases carbon dioxide into the atmosphere. To reach carbon neutrality by 2050, it would be necessary to implement innovative measures in the cement industry to deliver carbon neutrality. In this respect, it is striking that the new cement types made with high contents of industrial by-products will act as a lever to combat climate change. Accordingly, the purpose of this study is to assess coal–ash blended cements in light of climate change mitigation. In particular, ground coal bottom ash could be considered as a novel constituent for common cement production. The performance of these coal–ash mortars was assessed by measuring pozzolanic reactivity, mechanical strength gain, and microstructural characteristics. Mortars were made with 10%, 25%, or 35% of coal ash (fly ash and/or bottom ash). Therefore, by considering an emission intensity factor of 830 kgCO2/kg of clinker, a reduction in carbon dioxide emissions for all coal fly ash cements is expected, which will be about 83 kgCO2/kg of cement, 208 kgCO2/kg of cement, and 290 kgCO2/kg of cement, respectively. Ground coal bottom ash presented similar characteristics to the coal fly ash. Consequently, ground coal bottom ash is a promising Portland cement constituent with properties comparable to coal fly ash, and its increased usage can contribute to the climate change mitigation. Full article
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Article
Comparison and Determination of Optimal Machine Learning Model for Predicting Generation of Coal Fly Ash
Crystals 2022, 12(4), 556; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040556 - 15 Apr 2022
Viewed by 450
Abstract
The rapid development of industry keeps increasing the demand for energy. Coal, as the main energy source, has a huge level of consumption, resulting in the continuous generation of its combustion byproduct coal fly ash (CFA). The accumulated CFA will occupy a large [...] Read more.
The rapid development of industry keeps increasing the demand for energy. Coal, as the main energy source, has a huge level of consumption, resulting in the continuous generation of its combustion byproduct coal fly ash (CFA). The accumulated CFA will occupy a large amount of land, but also cause serious environmental pollution and personal injury, which makes the resource utilization of CFA gradually to be attached importance. However, given the variability of the amount of CFA generation, predicting it in advance is the basis to ensure effective disposal and rational utilization. In this study, CFA generation was taken as the target variable, three machine learning (ML) algorithms were used to construct the model, and four evaluation indices were used to evaluate its performance. The results showed that the DNN model with the R = 0.89, R2 = 0.77 on the testing set performed better than the traditional multiple linear regression equation and other ML algorithms, and the feasibility of DNN as the optimal model framework was demonstrated. Applying this model framework to the engineering field enables managers to identify the next step of the disposal method in advance, so as to rationally allocate ways of recycling and utilization to maximize the use and sales benefits of CFA while minimizing its disposal costs. In addition, sensitivity analysis further explains ML’s internal decisions and verifies that coal consumption is more important than installed capacity, which provides a certain reference for ensuring the rational utilization of CFA. Full article
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Review
An Overview of Hierarchical Design of Textile-Based Sensor in Wearable Electronics
Crystals 2022, 12(4), 555; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040555 - 15 Apr 2022
Viewed by 512
Abstract
Smart textiles have recently aroused tremendous interests over the world because of their broad applications in wearable electronics, such as human healthcare, human motion detection, and intelligent robotics. Sensors are the primary components of wearable and flexible electronics, which convert various signals and [...] Read more.
Smart textiles have recently aroused tremendous interests over the world because of their broad applications in wearable electronics, such as human healthcare, human motion detection, and intelligent robotics. Sensors are the primary components of wearable and flexible electronics, which convert various signals and external stimuli into electrical signals. While traditional electronic sensors based on rigid silicon wafers can hardly conformably attach on the human body, textile materials including fabrics, yarns, and fibers afford promising alternatives due to their characteristics including light weight, flexibility, and breathability. Of fundamental importance are the needs for fabrics simultaneously having high electrical and mechanical performance. This article focused on the hierarchical design of the textile-based flexible sensor from a structure point of view. We first reviewed the selection of newly developed functional materials for textile-based sensors, including metals, conductive polymers, carbon nanomaterials, and other two-dimensional (2D) materials. Then, the hierarchical structure design principles on different levels from microscale to macroscale were discussed in detail. Special emphasis was placed on the microstructure control of fibers, configurational engineering of yarn, and pattern design of fabrics. Finally, the remaining challenges toward industrialization and commercialization that exist to date were presented. Full article
(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)
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Article
On Stress-Induced Polarization Effect in Ammonothermally Grown GaN Crystals
Crystals 2022, 12(4), 554; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040554 - 15 Apr 2022
Viewed by 393
Abstract
The results of basic ammonothermal crystallization of gallium nitride are described. The material is mainly analyzed in terms of the formation of stress (called stress-induced polarization effect) and defects (threading dislocations) appearing due to a stress relaxation process. Gallium nitride grown in different [...] Read more.
The results of basic ammonothermal crystallization of gallium nitride are described. The material is mainly analyzed in terms of the formation of stress (called stress-induced polarization effect) and defects (threading dislocations) appearing due to a stress relaxation process. Gallium nitride grown in different positions of the crystallization zone is examined in cross-polarized light. Interfaces between native ammonothermal seeds and new-grown gallium nitride layers are investigated in ultraviolet light. The etch pit densities in the seeds and the layers is determined and compared. Based on the obtained results a model of stress and defect formation is presented. New solutions for improving the structural quality of basic ammonothermal gallium nitride crystals are proposed. Full article
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Article
Adsorption and Sensing Properties of Formaldehyde on Chemically Modified Graphene Surfaces
Crystals 2022, 12(4), 553; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040553 - 15 Apr 2022
Cited by 1 | Viewed by 454
Abstract
Chemically modifying graphene (such as chemical doping) is a commonly used method to improve its formaldehyde sensing properties, but the microscopic mechanisms of heteroatoms in the adsorption and sensing process are still unclear. In this paper, the adsorption and sensing properties of formaldehyde [...] Read more.
Chemically modifying graphene (such as chemical doping) is a commonly used method to improve its formaldehyde sensing properties, but the microscopic mechanisms of heteroatoms in the adsorption and sensing process are still unclear. In this paper, the adsorption and sensing properties of formaldehyde on graphene surfaces modified by X doping (X = B, N, O, P, S, Mg and Al) were systematically investigated by first-principles calculations. The adsorption geometries, adsorption energies, charge transfers, and electronic structures were obtained and analyzed. The adsorption strengths of HCHO molecule on the Mg- and Al-doped graphene surfaces were stronger than those of non-metal (B, N, O, P and S)-doped cases. These results showed that the Mg- or Al-doped graphene was better for HCHO detecting than the non-metal-doped graphene systems. The sensing properties were simulated by theNEGF method for the two-probe nano-sensors constructed from Al- and Mg-doped graphene. The maximum sensing responses of nano-sensors based on Al- and Mg-doped graphene were obtained to be 107% and 60%, respectively. The present study supplies a theoretical basis for designing superior graphene-based HCHO gas sensors. Full article
(This article belongs to the Special Issue Advanced Technologies in Graphene Materials and Devices)
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Article
Luminescent Color-Adjustable Europium and Terbium Co-Doped Strontium Molybdate Phosphors Synthesized at Room Temperature Applied to Flexible Composite for LED Filter
Crystals 2022, 12(4), 552; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040552 - 15 Apr 2022
Cited by 1 | Viewed by 463
Abstract
In this study, terbium and europium rare-earth ions were single-doped and co-doped to synthesized SoMoO4 phosphor at room temperature. The samples prepared synthesized crystalline SrMoO4 powder by the co-precipitation. Samples had a tetragonal structure in XRD analysis and d(112) spacing [...] Read more.
In this study, terbium and europium rare-earth ions were single-doped and co-doped to synthesized SoMoO4 phosphor at room temperature. The samples prepared synthesized crystalline SrMoO4 powder by the co-precipitation. Samples had a tetragonal structure in XRD analysis and d(112) spacing was changed by rare-earth doping. As the amount of rare earth added increased, a secondary phase appeared, and the structure changed. The synthesized SrMoO4:Tb3+ phosphors showed a green light emission at 544 nm under 287 nm, SrMoO4:Eu3+ phosphors showed a red light emission at 613 nm under 290 nm, and SrMoO4:[Eu3+]/[Tb3+] phosphor showed a yellow-white light emission at 544 and 613 nm when excited at 287 nm. The synthesized phosphor exhibited a change in green and red luminescence intensity based on the amount of Eu3+ doped and showed strong red luminescence as the Eu3+ doping increased. To use the SrMoO4:[Eu3+]/[Tb3+] phosphor with these characteristics in an LED color filter, a flexible composite prepared by mixing with PDMS showed green, red, and yellow-white emission under a UV-lamp. Full article
(This article belongs to the Topic Optoelectronic Materials)
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Article
Microwave-Absorbing Properties of PbMg1/3Nb2/3O3-PbZrO3-PbTiO3-PbGeO3 (PMN-PZT-PG) Solid Solutions on a Microstrip Line in the Microwave Range
Crystals 2022, 12(4), 551; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040551 - 15 Apr 2022
Viewed by 392
Abstract
In this paper, a brief review of the current state of research on ferroelectric, ferromagnetic, and multiferroic materials in the microwave range is given, and the main research methods are described. The main areas of application of functional materials in radio electronics are [...] Read more.
In this paper, a brief review of the current state of research on ferroelectric, ferromagnetic, and multiferroic materials in the microwave range is given, and the main research methods are described. The main areas of application of functional materials in radio electronics are outlined. Multicomponent ferroelectric media based on ferroelectric (PbTiO3), antiferroelectric (PbZrO3), and relaxors (PbMg1/3Nb2/3O3) are considered promising radio-absorbing materials. A method for comparing the electrical parameters of samples using a microstrip line and a network analyzer is described in detail, in which cylindrical samples were placed on a microstrip line. The measurements were carried out in the frequency range 10 MHz–20 GHz. Based on the frequency dependences of the S parameters, the relationships between the resonant frequencies of the samples and their composition were determined. The frequency dependences of the absorption coefficient were calculated for materials of various compositions. For each composition, the effective absorption band was calculated, and a pattern of its distribution over the concentrations of the system components was plotted. For empty areas of the phase diagram, interpolation was performed using the obtained results, which made it possible to obtain a qualitative idea of the radio-absorbing properties of the entire system. It was revealed that the compositions with the greatest variety of different phases had the widest absorption band. The results obtained will help in future research and composition selection for further development of microwave devices such as dielectric resonators, filters, and attenuators. Full article
(This article belongs to the Special Issue Ferroelectrics)
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Article
Baloxavir Marboxil Polymorphs: Investigating the Influence of Molecule Packing on the Dissolution Behavior
Crystals 2022, 12(4), 550; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040550 - 15 Apr 2022
Viewed by 444
Abstract
Baloxavir marboxil (BXM) is a new blockbuster FDA-approved anti-influenza virus agent. However, its poor solubility has limited its oral bioavailability. In this study, BXM was crystallized from several organic solvents, obtaining three polymorphs, and their dissolution behaviors were studied. Detailed crystallographic examination revealed [...] Read more.
Baloxavir marboxil (BXM) is a new blockbuster FDA-approved anti-influenza virus agent. However, its poor solubility has limited its oral bioavailability. In this study, BXM was crystallized from several organic solvents, obtaining three polymorphs, and their dissolution behaviors were studied. Detailed crystallographic examination revealed that Form I is monoclinic, space group P21, with unit cell parameters a = 7.1159 (3) Å, b = 20.1967 (8) Å, c = 9.4878 (4) Å, β = 109.033 (1)°, V = 1289.02 (9) Å3, and Z = 2, and Form II is monoclinic, space group P21, with unit cell parameters a = 7.1002 (14) Å, b = 39.310 (7) Å, c = 9.7808 (18) Å, β = 110.966 (5)°, V = 2549.2 (8) Å3, and Z = 4. Form I has a rectangular three-dimensional energy frameworks net, while Form II has a two-dimensional net. On the other hand, Form II has a much larger percentage of its surface area of exposed hydrogen bond acceptors than Form I. These crystallographic features offered increased solubility and dissolution rate to Form II. The results of stability and solubility experiments suggest that Form II may be preferred in the solid form used for the industrial preparation of BXM medicinal products. Full article
(This article belongs to the Special Issue Polymorphism in Crystals)
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Article
Light-Induced Structures and Microparticle Transportation in a Free-Surface Frustrated Chiral Nematic Film
Crystals 2022, 12(4), 549; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040549 - 14 Apr 2022
Viewed by 524
Abstract
Local illumination with a light beam leads to thermo-orientational processes in a frustrated chiral nematic film with a free surface. Light-induced hydrodynamic flow and orientational structure create an adaptive platform for the collection, translation and rotation of suspended spherical microparticles. The demonstrated approach [...] Read more.
Local illumination with a light beam leads to thermo-orientational processes in a frustrated chiral nematic film with a free surface. Light-induced hydrodynamic flow and orientational structure create an adaptive platform for the collection, translation and rotation of suspended spherical microparticles. The demonstrated approach has potential applications in soft robotics, micro-object delivery systems, and other micro- and nanotechnologies. Full article
(This article belongs to the Special Issue Optical and Molecular Aspects of Liquid Crystals)
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Communication
Microstructure and Superelastic Properties of FeNiCoAlTi Single Crystals with the <100> Orientation under Tension
Crystals 2022, 12(4), 548; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040548 - 14 Apr 2022
Viewed by 403
Abstract
The microstructure and superelastic response of an Fe41Ni28Co17Al11.5Ti2.5 (at.%) single crystal along the <100> orientation was investigated under tension at room temperature after aging at 600 °C for 24 h. From the superelastic results, [...] Read more.
The microstructure and superelastic response of an Fe41Ni28Co17Al11.5Ti2.5 (at.%) single crystal along the <100> orientation was investigated under tension at room temperature after aging at 600 °C for 24 h. From the superelastic results, the samples aged at 600 °C for 24 h exhibited 4.5% recoverable strain at room temperature. The digital image correlation (DIC) method was used to observe the strain distribution during the 6.5% applied strain loading. The DIC results showed that the strain was uniformly distributed during the loading and unloading cycles. Only one martensite variant was observed from the DIC results. This was related to the aging heat treatment times. The martensite morphology became a single variant with a longer aging time. The thermo-magnetization results indicated that the phase transformation and temperature hysteresis was around 36 °C. Increasing the magnetic field from 0.05 to 7 Tesla, the transformation temperatures increased. The maximum magnetization was 160 emu/g under the magnetic field of 7 Tesla. From the transmission electron microscopy results, the L12 precipitates were around 10 nm in size, and they were high in Ni content and low in Fe content. Full article
(This article belongs to the Special Issue Crystal Plasticity (Volume II))
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Article
Fast Lead-Free Humidity Sensor Based on Hybrid Halide Perovskite
Crystals 2022, 12(4), 547; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040547 - 14 Apr 2022
Viewed by 516
Abstract
An environmentally friendly analog of the prominent methylammonium lead halide perovskite, methylammonium bismuth bromide (MA3Bi2Br9), was prepared and investigated in the form of powder, single crystals and nanowires. Complete characterization via synchrotron X-ray diffraction data showed that [...] Read more.
An environmentally friendly analog of the prominent methylammonium lead halide perovskite, methylammonium bismuth bromide (MA3Bi2Br9), was prepared and investigated in the form of powder, single crystals and nanowires. Complete characterization via synchrotron X-ray diffraction data showed that the bulk crystal does not incorporate water into the structure. At the same time, water is absorbed on the surface of the crystal, and this modification leads to the changes in the resistivity of the material, thus making MA3Bi2Br9 an excellent candidate for use as a humidity sensor. The novel sensor was prepared from powder-pressed pellets with attached carbon electrodes and was characterized by being able to detect relative humidity over the full range (0.7–96% RH) at ambient temperature. Compared to commercial and literature values, the response and recovery times are very fast (down to 1.5 s/1.5 s). Full article
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Article
Identification, Characterization, and Preliminary X-ray Diffraction Analysis of a Novel Esterase (ScEst) from Staphylococcus chromogenes
Crystals 2022, 12(4), 546; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040546 - 13 Apr 2022
Viewed by 402
Abstract
Ester prodrugs can develop novel antibiotics and have potential therapeutic applications against multiple drug-resistant bacteria. The antimicrobial activity of these prodrugs is activated after being cleaved by the esterases produced by the pathogen. Here, novel esterase ScEst originating from Staphylococcus chromogenes NCTC10530, [...] Read more.
Ester prodrugs can develop novel antibiotics and have potential therapeutic applications against multiple drug-resistant bacteria. The antimicrobial activity of these prodrugs is activated after being cleaved by the esterases produced by the pathogen. Here, novel esterase ScEst originating from Staphylococcus chromogenes NCTC10530, which causes dairy cow mastitis, was identified, characterized, and analyzed using X-ray crystallography. The gene encoding ScEst was cloned into the pVFT1S vector and overexpressed in E. coli. The recombinant ScEst protein was obtained by affinity and size-exclusion purification. ScEst showed substrate preference for the short chain length of acyl derivatives. It was crystallized in an optimized solution composed of 0.25 M ammonium citrate tribasic (pH 7.0) and 20% PEG 3350 at 296 K. A total of 360 X-ray diffraction images were collected at a 1.66 Å resolution. ScEst crystal belongs to the space group of P212121 with the unit cell parameters of a = 50.23 Å, b = 68.69 Å, c = 71.15 Å, and α = β = γ = 90°. Structure refinement after molecular replacement is under progress. Further biochemical studies will elucidate the hydrolysis mechanism of ScEst. Overall, this study is the first to report the functional characterization of an esterase from Staphylococcus chromogenes, which is potentially useful in elaborating its hydrolysis mechanism. Full article
(This article belongs to the Special Issue Crystallographic Studies of Enzymes (Volume II))
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Article
Comparative Study of Cu/ZSM-5 Catalysts Synthesized by Two Ion-Exchange Methods
Crystals 2022, 12(4), 545; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040545 - 13 Apr 2022
Viewed by 401
Abstract
As catalysis is one of the pillars of green chemistry, this work aimed at continuing the development of synthesized catalysts under controlled conditions that allow the attainment of materials with the best physicochemical properties for the process for which they were designed. Based [...] Read more.
As catalysis is one of the pillars of green chemistry, this work aimed at continuing the development of synthesized catalysts under controlled conditions that allow the attainment of materials with the best physicochemical properties for the process for which they were designed. Based on this, the synthesis, characterization, and comparison of copper-based catalysts supported on ammonium and acidic ZSM-5-type zeolite by two ion exchange methods, liquid phase and solid state, are presented. The catalysts obtained were characterized by SEM/EDS, FTIR, XRD, and TPR to study the effect of the synthesis method on the physicochemical properties of each catalyst. The SEM/EDS results showed a homogeneous distribution of copper in the zeolite and the TPR led to determining the temperature ranges for the reduction of Cu2+ → Cu+ → Cu0. Furthermore, the X-ray results showed no modification of the structure of the zeolite after ion exchange, heat treatment, and TPR analysis. Full article
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Article
Study on Novel Powder Metallurgy Al-Si Brazing Filler Metal with Flux
Crystals 2022, 12(4), 544; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040544 - 13 Apr 2022
Viewed by 424
Abstract
Green brazing is one of the key basic technologies in the manufacturing industry, and the wide application of composite brazing filler metals is a significant method for realizing green and automatic brazing. In the present study, an investigation was conducted into a novel [...] Read more.
Green brazing is one of the key basic technologies in the manufacturing industry, and the wide application of composite brazing filler metals is a significant method for realizing green and automatic brazing. In the present study, an investigation was conducted into a novel powder metallurgy Al-Si brazing filler metal with flux and the resulting brazed joints of 3003/6061 aluminum alloy. By means of scanning electron microscopy and energy-dispersive analysis, the effect of moisture-resistance performance on the microstructure and the properties of Al-Si brazing filler metal with flux and brazing joint were analyzed. The results reveal that the new type of powder metallurgy Al-12Si brazing filler metal had better moisture-resistance performance than the seamed flux cored brazing filler metal. In an environment with a humidity of 90% and a temperature of 40 °C for 7 days, the moisture absorption rate of the powder metallurgy Al-12Si brazing filler metal with flux was only 0.17%. The wet spreading area of the new powder metallurgy Al-12Si brazing filler metal treated for 3 days in a humid environment was 320 mm2, which was 7% less than that in the dry state. At the same time, the spreading area of the seamed flux cored brazing filler metal under the same conditions was only 80.9% of that in the dry state. The fracture strengths of the 3003 and 6061 aluminum alloy joints brazed by the wetted powder metallurgy Al-12Si brazing filler metal with flux were satisfactory, and scanning electron microscopy examination of the braze-zone revealed that relatively sound joints were obtained. However, obvious pores were observed in the braze-zone of the wetted seamed flux cored brazing filler. The maximum diameter of the pores was increased from 28 μm to 68 μm in the brazing area. Full article
(This article belongs to the Special Issue Advances of Welding Materials)
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Article
Periodicity of Superatomic Hybrid Orbitals in Substituted Superatoms and Superatomic-like [email protected]12 (X = Li~Kr) Clusters
Crystals 2022, 12(4), 543; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040543 - 12 Apr 2022
Viewed by 407
Abstract
A superatom is a cluster composed of a specific number of atoms. We recently found that the superatom-like [email protected]12 (X = Li~Kr) clusters has the periodic energy levels of the specific orbitals 2S and 2P by means of the DV-Xα molecular orbital [...] Read more.
A superatom is a cluster composed of a specific number of atoms. We recently found that the superatom-like [email protected]12 (X = Li~Kr) clusters has the periodic energy levels of the specific orbitals 2S and 2P by means of the DV-Xα molecular orbital calculation method. This periodicity in energy levels has not been seen in 1D or 1F orbitals. We supposed that the periodicity of the energy levels of the 2S and 2P superatomic-like orbitals come from the same symmetry between atomic orbitals as the central atom X and the surrounding specific orbitals, according to the Jellium model. Both the s and p atomic orbitals of the central atom X in the superatom-like [email protected]12 have a large shielding effect, suggesting that the s and p atomic orbitals interact strongly with both 2S and 2P superatomic-like orbitals. The energy level periodicity has the potential to periodically change the number of electrons located in the 1D and 1F orbitals, which is related to magnetic properties and is expected to be useful for novel magnetic devices by periodically controlling the magnetism of superatoms. Full article
(This article belongs to the Topic First-Principles Simulation—Nano-Theory)
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Article
Resonance Analysis of Piezoelectric Bulk Acoustic Wave Devices Based on YCOB Crystals with Monoclinic Symmetry Excited by Lateral Electric Fields
Crystals 2022, 12(4), 542; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040542 - 12 Apr 2022
Viewed by 372
Abstract
The monoclinic YCOB crystal still maintains good piezoelectric properties at 800 °C; thus, it has a good application prospect in high-temperature piezoelectric acoustic wave sensors. However, due to the lower symmetry compared crystals in trigonal and tetragonal systems, the exciting characteristics of piezoelectric [...] Read more.
The monoclinic YCOB crystal still maintains good piezoelectric properties at 800 °C; thus, it has a good application prospect in high-temperature piezoelectric acoustic wave sensors. However, due to the lower symmetry compared crystals in trigonal and tetragonal systems, the exciting characteristics of piezoelectric plates based on monoclinic YCOB crystals are more complicated. The vibration analysis model of lateral-field-excitation (LFE) devices based on monoclinic crystals is scarce; thus, the coupling relationships between different vibration modes and energy-trapping characteristics of the devices are unclear, which hinders the optimal design of devices. In this paper, by using Mindlin plate theory, the high-frequency vibrations of piezoelectric resonators based on monoclinic YCOB crystal plates excited by a lateral electric field are modeled and analyzed. The coupling relationships between the vibration modes of the device are clarified. The influences of the electrode width, electrode/plate mass ratio and electrode gap value on resonances and energy-trapping characteristics of the device are achieved. In addition, the effects of the structure parameters on the mass sensitivity of the monoclinic YCOB LFE devices are investigated, which are further verified by FEM simulations. The results are crucial to obtaining good resonance and sensing characteristics for LFE high-temperature piezoelectric sensors based on crystals with monoclinic symmetry. Full article
(This article belongs to the Special Issue Ferroelectrics)
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Review
Progress of InGaN-Based Red Micro-Light Emitting Diodes
Crystals 2022, 12(4), 541; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040541 - 12 Apr 2022
Cited by 1 | Viewed by 653
Abstract
InGaN-based red micro-size light-emitting diodes (μLEDs) have become very attractive. Compared to common AlInGaP-based red µLEDs, the external quantum efficiency (EQE) of InGaN red µLEDs has less influence from the size effect. Moreover, the InGaN red µLEDs exhibit a much more robust device [...] Read more.
InGaN-based red micro-size light-emitting diodes (μLEDs) have become very attractive. Compared to common AlInGaP-based red µLEDs, the external quantum efficiency (EQE) of InGaN red µLEDs has less influence from the size effect. Moreover, the InGaN red µLEDs exhibit a much more robust device performance even operating at a high temperature of up to 400 K. We review the progress of InGaN red μLEDs. Novel growth methods to relax the strain and increase the growth temperature of InGaN red quantum wells are discussed. Full article
(This article belongs to the Special Issue III-Nitride-Based Light-Emitting Devices)
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Article
Employing the Defective Photonic Crystal Composed of Nanocomposite Superconducting Material in Detection of Cancerous Brain Tumors Biosensor: Computational Study
Crystals 2022, 12(4), 540; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040540 - 12 Apr 2022
Cited by 1 | Viewed by 472
Abstract
The present research is focused on the externally tunable defect mode properties of a one dimensional (1D) defective photonic crystal (DPhC) for fast detection of cancerous brain tumors. The proposed design has utilized conventional 1D DPhC whose cavity is coated with SiO2 [...] Read more.
The present research is focused on the externally tunable defect mode properties of a one dimensional (1D) defective photonic crystal (DPhC) for fast detection of cancerous brain tumors. The proposed design has utilized conventional 1D DPhC whose cavity is coated with SiO2 nanoparticles embedded in a superconducting material layer called a nanocomposite layer. The purpose of a nanocomposite superconducting layer is to induce temperature dependent external tuning of the defect mode inside PBG, in addition, to changing in the angle of incidence. The inclusion of a nanocomposite layer also improves the interaction between light and different brain tissue samples under examination. In order to investigate the transmission properties of the proposed structure the transfer matrix formulation in addition to the MATLAB computational tool has been used. First, we have chosen the optimized internal parameters at normal incidence to obtain the maximum performance of the design. Secondly, the effect of change in angle of incidence has been studied to further increase the performance by means of sensitivity, quality factor, the figure of merit and limit of detection to ensure external tuning of defect mode. After achieving a maximum value of sensitivity (4139.24 nm/RIU) corresponding to a sample containing a wall of brain tissues at θ = 63° we have further investigated the effect of change in temperature of nanocomposite layers on the position and intensity both of the defect mode inside PBG. We have found that the increase in temperature results in minute changes in sensitivity but a significant increase in the intensity of defect mode which is highly required in any photonic biosensing design. The findings of this study may be very useful for designing various bio-sensing structures which could have a significant and decisive role in the field of biomedical applications. Full article
(This article belongs to the Special Issue Recent Advances in Photonic Crystal and Optical Devices)
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Article
Morphology and FTIR Characteristics of the Alluvial Diamond from the Yangtze Craton, China
Crystals 2022, 12(4), 539; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040539 - 12 Apr 2022
Viewed by 408
Abstract
A total of 48 natural alluvial diamonds from the Yangtze Craton, China, also called Hunan diamonds, were studied using morphology and IR spectroscopy. These diamond samples, collected downstream of the Yuan River, Hunan Province, with unknown host-rock source(s), were observed by scanning electron [...] Read more.
A total of 48 natural alluvial diamonds from the Yangtze Craton, China, also called Hunan diamonds, were studied using morphology and IR spectroscopy. These diamond samples, collected downstream of the Yuan River, Hunan Province, with unknown host-rock source(s), were observed by scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR). Most Hunan diamonds are monocrystal forms of octahedra, tetrahexahedra (THH) and dodecahedra; octahedral–rhom-dodecahedral transitional behaviors and irregular forms are also visible. Trigons and tetragons, terraces and shield-shaped laminae are surface features that frequently indicate dissolution and reabsorption; green and brown spots, network patterns, and other mechanical abrasion marks are typical evidence of long-time deposition and transportation of Hunan diamonds. The main types of Hunan diamonds are type IaAB and type Ⅱa. Diamond samples have a wide range of total nitrogen content (Ntot) from 196–1094 ppm. Two populations are distinguished by two-peak distribution models of NA (A-center concentrations) and %B (proportion of aggregated nitrogen). Hunan diamonds are low in structure hydrogen (0.03–4.67 cm−1, mostly below 1 cm−1) and platelets (0.23–17 cm−1, mostly below 2 cm−1). Moreover, there is a significant positive correlation between the hydrogen correlation peak and Ntot, which is similar to Argyle diamonds. The temperature conditions of the diamond formation have been estimated at 1075–1180 °C, mainly conforming to the kimberlite diamond range. Besides, some samples with slightly higher temperatures are close to the ultramafic-related Juina diamonds. Therefore, the FTIR characteristics analysis and comparison indicate the multiple sources of Hunan diamonds. Full article
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Communication
Identification, Characterization, and Preliminary X-ray Diffraction Analysis of a Single Stranded DNA Binding Protein (LjSSB) from Psychrophilic Lacinutrix jangbogonensis PAMC 27137
Crystals 2022, 12(4), 538; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040538 - 11 Apr 2022
Viewed by 418
Abstract
Single-stranded DNA-binding proteins (SSBs) are essential for DNA metabolism, including repair and replication, in all organisms. SSBs have potential applications in molecular biology and in analytical methods. In this study, for the first time, we purified, structurally characterized, and analyzed psychrophilic SSB (LjSSB) [...] Read more.
Single-stranded DNA-binding proteins (SSBs) are essential for DNA metabolism, including repair and replication, in all organisms. SSBs have potential applications in molecular biology and in analytical methods. In this study, for the first time, we purified, structurally characterized, and analyzed psychrophilic SSB (LjSSB) from Lacinutrix jangbogonensis PAMC 27137 isolated from the Antarctic region. LjSSB has a relatively short amino acid sequence, consisting of 111 residues, with a molecular mass of 12.6 kDa. LjSSB protein was overexpressed in Escherichia coli BL21 (DE3) and analyzed for binding affinity using 20- and 35-mer deoxythymidine oligonucleotides (dT). In addition, the crystal structure of LjSSB at a resolution 2.6 Å was obtained. The LjSSB protein crystal belongs to the space group C222 with the unit cell parameters of a = 106.58 Å, b = 234.14 Å, c = 66.14 Å. The crystal structure was solved using molecular replacement, and subsequent iterative structure refinements and model building are currently under progress. Further, the complete structural information of LjSSB will provide a novel strategy for protein engineering and for the application on molecular biological techniques. Full article
(This article belongs to the Special Issue Crystallographic Studies of Enzymes (Volume II))
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Article
Improving Optoelectrical Properties of PEDOT: PSS by Organic Additive and Acid Treatment
Crystals 2022, 12(4), 537; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040537 - 11 Apr 2022
Viewed by 406
Abstract
This article demonstrates the change of structural and optical properties of poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) by organic additive and acid treatment. The addition of sorbitol and maltitol can disperse the micelles of PEDOT: PSS. The mechanism of the bond-breaking reaction [...] Read more.
This article demonstrates the change of structural and optical properties of poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) by organic additive and acid treatment. The addition of sorbitol and maltitol can disperse the micelles of PEDOT: PSS. The mechanism of the bond-breaking reaction was investigated and a model for the bond-breaking reaction is also proposed. Furthermore, multiple formic acid treatments were found to reduce the PSS content of PEDOT: PSS, resulting in an enhancement in conductivity (4.2 × 104 S/m). Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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