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Topic Review
Nucleation in Polymer Crystallization
Nucleation plays a vital role in polymer crystallization, in which chain connectivity and thus the multiple length and time scales make crystal nucleation of polymer chains an interesting but complex subject. Though the topic has been intensively studied in the past decades, there are still many open questions to answer. The final properties of semicrystalline polymer materials are affected by all of the following: the starting melt, paths of nucleation, organization of lamellar crystals and evolution of the final crystalline structures. In this viewpoint, we attempt to discuss some of the remaining open questions and corresponding concepts: non-equilibrated polymers, self-induced nucleation, microscopic kinetics of different processes, metastability of polymer lamellar crystals, hierarchical order and cooperativity involved in nucleation, etc. Addressing these open questions through a combination of novel concepts, new theories and advanced approaches provides a deeper understanding of the multifaceted process of crystal nucleation of polymers.
  • 1.7K
  • 25 Jun 2021
Topic Review
New Modification of PbF(IO3)
New crystals of PbF(IO3) polytype modification are synthesized hydrothermally and demonstrate strong SHG optical response. They are phase-matchable at the fundamental wavelength of 1064 nm. The crystal structure was solved in two space groups, orthorhombic C2ma and monoclinic Pn, of which monoclinic is true and is described with a twinning by mirror plane introduced in structural refinements taken into account. Orthorhombic symmetry was used in comparison with the related structures and deviation close similarity in the selected suggested family MX(IO3), M = Bi, Ba­, Pb, X= O, F, (OH) with series of members. These compounds were also characterizing as similar to Aurivillius phases with fluorite-like layer and perovskite-like layer substituted by (IO3) groups. The optical nonlinearity of the iodates of the Aurivillius family and structurally related iodates is determined by the polar orientation of the iodate groups, which make an overwhelming contribution to the optical nonlinearity. From crystal chemistry point of view, the heavy atoms in these structures are located in the second cation environments in relation to the iodate groups and indirectly affect the nonlinearity. In particular, large Ba-cations without single electron pairs provoke a symmetric variant of the Aurivillius type structure, in contrast to the acentric Bi3+ and Pb2+ cations known in polar iodates with strong second-order optical nonlinearity. There is wide diversity in the extended series of related compounds which includes variation of fluorite-like layers (single or double), perovskite-like layers presented by octahedral or more complicate polyhedral, or by IO3 (BrO3) groups, or by Cl-atoms, or by NH4-groups. This allows the development of future search for new promising phases.
  • 330
  • 01 Feb 2023
Topic Review
Modification Strategies of Pristine Graphitic Carbon Nitride
Graphitic carbon nitride (g-C3N4), as the significant metal-free semiconductor photocatalyst, holds great potential in the application of the photocatalytic nitrogen oxides (NOx) removal process due to its plentiful extraordinary advantages, such as visible light response properties, mild bandgap, low cost, facile preparation and high thermal stability. However, pristine g-C3N4 prepared using the traditional high-temperature solid reaction suffers from low specific surface areas and low crystallinity owing to kinetic hindrance, which results in small specific surface areas, few reactive sites, limited light-harvesting capacity, rapid recombination of photogenerated charge carriers and unsatisfactory photocatalytic NOx removal performance. In order to improve the photocatalytic performance of pristine g-C3N4, a variety of modification strategies have been developed including metal doping, non-metal doping, defect engineering, crystallinity optimization, morphology controlling and heterojunction construction.
  • 609
  • 06 Feb 2023
Topic Review
Methods for Protein Crystallization
Proteins are biopolymers consisting of amino acids linked by peptide bonds. A peptide bond is a type of amide bond that occurs during the formation of proteins and peptides as a result of the interaction of the α-amino group (-NH2) of one amino acid with the α-carboxyl group (-COOH) of another amino acid. The main method for determining the spatial structure of a protein is X-ray structural analysis of protein crystals. The main difficulty in applying this method is in obtaining a perfect protein-crystal. 
  • 595
  • 28 Jan 2023
Topic Review
Mechanical Milling
Mechanical milling (MM) has attracted great attention as a powerful tool for the synthesis of a variety of sophisticated materials, including equilibrium, nonequilibrium (e.g., amorphous, quasicrystals, nanodiamonds, carbon nanotubes, nanocrystalline powders), and nanocomposite materials. The MM is a unique process in that it involves a solid-state interaction between the reactant materials’ fresh powder surfaces at room temperature. As a result, it has been used to fabricate alloys and compounds that are difficult or impossible to acquire using standard melting and casting processes.
  • 2.1K
  • 20 Oct 2021
Topic Review
Liquid Crystalline Materials Based on Copper(I) Complexes
This paper provides insight into the various studies that have already been carried out on liquid crystalline materials based on copper(I) complexes. Even though the study of copper(I) complexes with respect to their liquid crystalline property is quite few, metallomesogens prepared with different structural components and ligands from groups such as aza macrocycles, alkyl thiolates, ethers, isocyanides, phenanthroline, Schiff bases, pyrazoles, phosphine, biquinoline, and benzoyl thiourea have been reported. A special section is dedicated to the discussion of the emission properties of copper(I) metallomesogens.
  • 402
  • 28 Jul 2023
Topic Review
Lead-Free Perovskite Single Crystals
Lead-free perovskites have received remarkable attention because of their nontoxicity, low-cost fabrication, and spectacular properties including controlled bandgap, long diffusion length of charge carrier, large absorption coefficient, and high photoluminescence quantum yield. Compared with the widely investigated polycrystals, single crystals have advantages of lower trap densities, longer diffusion length of carrier, and extended absorption spectrum due to the lack of grain boundaries, which facilitates their potential in different fields including photodetectors, solar cells, X-ray detectors, light-emitting diodes, and so on. 
  • 629
  • 30 Nov 2021
Topic Review
Inhibitor-Enzyme Complexes for New Anti-TB Agents
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is the most devastating human pathogen, as confirmed by the latest TB Report published in October.
  • 393
  • 23 Jan 2022
Topic Review Peer Reviewed
Homogenization Methods of Lattice Materials
The existing methods for analyzing the behaviors of lattice materials require high computational power. The homogenization method is the alternative way to overcome this issue. Homogenization is an analysis to understand the behavior of an area of lattice material from a small portion for rapid analysis and precise approximation. This paper provides a summary of some representative methodologies in homogenization.
  • 648
  • 06 Jun 2022
Topic Review
High Pressure Macromolecular Crystallography
Since its introduction in the early 1970s, high pressure crystallography (HPX) has shown great potential for the investigation of different types of matter. Using diamond anvil cells, HPX is an emerging technique that has been rapidly implemented, making it available to biologists, and there is immense potential for utilizing this technique in biological systems in the future. At the molecular level, high-pressure crystallographic investigation provides information on structural characteristics that not only determine the native conformation of a protein but also the conformations with higher free-energy, thus revealing function-related structural changes and properties that can be modified as a result of pressurization. The increase in the number of crystal structures of different macromolecules determined under high pressure over the last five decades can be ascribed mainly to two factors: the emergence of high-pressure cells with very large, open angles, and the advent of third generation synchrotron sources. The use of high pressure crystallography as a research tool has been shown to contribute to the advancements in the basic fields of biochemistry (protein misfolding and aggregation), biophysics (protein stability), and biotechnology (food processing).
  • 1.6K
  • 04 Apr 2023
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