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AI SHEDS LIGHT ON CRYSTAL GROWTH Researchers at Nagoya University, Japan, recently used artificial intelligence to analyze the image data of polycrystalline silicon, a material widely used in solar panels. [...]

The [sigma].sub.2 receptor has attracted intense interest in cancer imaging.sup.1, psychiatric disease.sup.2, neuropathic pain.sup.3-5 and other areas of biology.sup.6,7. Here we determined the crystal structure of this receptor in complex with the clinical candidate roluperidone.sup.2 and the tool compound PB28.sup.8. These structures templated a large-scale docking screen of 490 million virtual molecules, of which 484 compounds were synthesized and tested. We identified 127 new chemotypes with affinities superior to 1 [mu]M, 31 of which had affinities superior to 50 nM. The hit rate fell smoothly and monotonically with docking score. We optimized three hits for potency and selectivity, and achieved affinities that ranged from 3 to 48 nM, with up to 250-fold selectivity versus the [sigma].sub.1 receptor. Crystal structures of two ligands bound to the [sigma].sub.2 receptor confirmed the docked poses. To investigate the contribution of the [sigma].sub.2 receptor in pain, two potent [sigma].sub.2-selective ligands and one potent [sigma].sub.1/[sigma].sub.2 non-selective ligand were tested for efficacy in a mouse model of neuropathic pain. All three ligands showed time-dependent decreases in mechanical hypersensitivity in the spared nerve injury model.sup.9, suggesting that the [sigma].sub.2 receptor has a role in nociception. This study illustrates the opportunities for rapid discovery of in vivo probes through structure-based screens of ultra large libraries, enabling study of underexplored areas of biology. Crystal structures of the [sigma].sub.2 receptor are determined and used to perform a docking screen of nearly 500 million molecules, identifying [sigma].sub.2-selective ligands and providing insight into the role of [sigma].sub.2 in neuropathic pain., Author(s): Assaf Alon [sup.1] , Jiankun Lyu [sup.2] , Joao M. Braz [sup.3] , Tia A. Tummino [sup.2] [sup.4] , Veronica Craik [sup.3] , Matthew J. O'Meara [sup.5] , Chase [...]

With polymer pipes being used more commonly, performance requirements are increasing. Studies on the enhancement of mechanical properties of polymer pipes are particularly important. In this study, a self-designed annular expansion pipe extruder head was used to enhance the mechanical properties of HDPE pipes. Different morphologies of the HDPE pipes were produced under different processing conditions. When the extrusion angle was 30[degrees] (P30), the best mechanical properties were obtained. The hoop tensile strength and axial tensile strength were 14.5% and 41.0% higher, respectively, compared with the specimen without expansion (P0). This improvement of mechanical properties can be attributed to several reasons. First, the processing parameters of P30 reached the threshold shear rate and strain for shish-kebab formation, as shown by scanning electron microscopy. Second, P30 has the highest orientation parameter and crystallinity of 0.679 and 67.27%, respectively, from 2D wide-angle diffraction (WAXD). Polarized FTIR shows the same trend as 2DWAXD. Third, the outer bamboo-like self-reinforced structure is formed inside the pipe at 30[degrees] expansion angle while the core layer has a well-formed crystal structure; the special structure improves the overall performance of HDPE pipe. This method can be utilized in large-scale industrial production. KEYWORDS crystallization, extrusion, orientation, 1 | INTRODUCTION Owing to their good performance and affordable price, polyethylene pipes are widely used in various fields. They have the following advantages over steel pipes: light weight, good [...]

The Avalon Peninsula on the island of Newfoundland, Canada, defined as the type zone of Avalonia, is believed to have been impacted by several orogenetic and deformation events since the Neoproterozoic. Previous studies have determined that the lowest degree of metamorphism reached in the successions was of the prehnite--pumpellyite or greenschist facies. We sampled and measured 13 mainly clastic sedimentary sections ranging from the late Ediacaran to the Early Ordovician and analyzed the illite 'crystallinity' of 331 samples using the Kubler index. Our results show that the occurrence of diagenetic zones relates to lithology, age and burial depth, and regional setting. Samples adjacent to the fault zones bounding the Holyrood Horst experienced the highest degree of metamorphism (anchizone) in the study area. The lowest degree of thermal alteration occurs in the high stratigraphic sections at the centre of the horst structure where shallow diagenetic conditions are preserved. Fault zones, which were probably active during at least the Acadian Orogeny, may have served as potential paths for hot fluids in bounding areas of the horst, whereas the centre of the horst remained almost unaffected by any metamorphic overprint. The thermal impact decreases from the Bonavista Peninsula west of the study area from greenschist facies to anchizonal and diagenetic. The study area experienced lower metamorphic conditions than those in the major regions of Avalonia south of the study area, namely the mainland of New Brunswick and Maine and eastward in Europe, but is in part consistent with a few other areas of Avalonia, such as the Mira Terrane and the Antigonish Highlands in Nova Scotia. Key words: illite 'crystallinity', Kubler index, diagenesis, Holyrood Horst, Avalon Peninsula, southeastern Newfoundland. La peninsule dAvalon (Terre-Neuve, Canada), definie comme etant la region type de lAvalonie, aurait subi les effets de plusieurs episodes orogeniques et de deformation depuis le Neoproterozoique. Des etudes passees ont determine que le metamorphisme le plus faible atteint durant ces episodes est au facies prehnite-pumpellyite ou des schistes verts. Nous avons echantillonne et mesure 13 coupes sedimentaires principalement clastiques allant de l'Ediacarien tardif a l'Ordovicien precoce et analyse la << cristallinite >> de l'illite de 331 echantillons a l'aide de l'indice de Kubler. Nos resultats demontrent que la presence de zones diagenetiques est reliee au type de roche, a l'age et a la profondeur d'enfouissement, respectivement, et au contexte regional. Des echantillons attenants aux zones de faille bordant le horst de Holyrood ont subi le metamorphisme le plus intense (anchizone) dans la region d'etude. Le degre le plus faible d'alteration thermique est observe dans les coupes stratigraphiques hautes situees au centre de la structure de horst, ou des conditions de diagenese peu profonde sont preservees. Des zones de faille, a tout le moins probablement actives durant l'orogenese acadienne, pourraient avoir servi de voies d'ecoulement de fluides chauds dans les zones bordant le horst, alors que le centre de ce dernier est demeure presque exempt de tout effet du metamorphisme. L'impact thermique diminue a partir de la peninsule de Bonavista, a l'ouest de la region d'etude, passant du facies des schistes verts a l'anchizone a la zone diagenetique. La region d'etude a subi des conditions de metamorphisme plus faibles que de grands secteurs de l'Avalonie au sud, dans la partie continentale du Nouveau-Brunswick et du Maine et plus a lest en Europe, mais qui concordent du moins partiellement avec celles de quelques autres regions de l'Avalonie, comme le terrane de Mira et les hautes terres d'Antigonish en Nouvelle-Ecosse. [Traduit par la Redaction] Mots-cles: cristallinite de l'illite, indice de Kubler, diagenese, horst de Holyrood, peninsule d'Avalon, sud-est de Terre-Neuve., Introduction The upper Ediacaran and lower Palaeozoic rocks of the Avalon Peninsula on the island of Newfoundland, Canada, have been studied for decades (e.g., Howell 1925; Hutchinson 1962; Fletcher 1972, [...]

What particular mechanical properties can be expected for materials composed of interlocked backbones has been a long-standing issue in materials science since the first reports on polycatenane and polyrotaxane in the 1970s.sup.1-3. Here we report a three-dimensional porous metal-organic crystal, which is exceptional in that its warps and wefts are connected only by catenation. This porous crystal is composed of a tetragonal lattice and dynamically changes its geometry upon guest molecule release, uptake and exchange, and also upon temperature variation even in a low temperature range. We indented.sup.4 the crystal along its a/b axes and obtained the Young's moduli of 1.77 [plus or minus] 0.16 GPa in N,N-dimethylformamide and 1.63 [plus or minus] 0.13 GPa in tetrahydrofuran, which are the lowest among those reported so far for porous metal-organic crystals.sup.5. To our surprise, hydrostatic compression showed that this elastic porous crystal was the most deformable along its c axis, where 5% contraction occurred without structural deterioration upon compression up to 0.88 GPa. The crystal structure obtained at 0.46 GPa showed that the catenated macrocycles move translationally upon contraction. We anticipate our mechanically interlocked molecule-based design to be a starting point for the development of porous materials with exotic mechanical properties. For example, squeezable porous crystals that may address an essential difficulty in realizing both high abilities of guest uptake and release are on the horizon. A rubber-like, metal-organic crystal is reported with a mechanically interlocked catenane backbone, which could allow for easy guest molecule uptake and release., Author(s): Wenjing Meng [sup.1] [sup.8] , Shun Kondo [sup.2] , Takuji Ito [sup.3] , Kazuki Komatsu [sup.4] , Jenny Pirillo [sup.5] , Yuh Hijikata [sup.5] , Yuichi Ikuhara [sup.2] , [...]

The precise stacking of different two-dimensional (2D) structures such as graphene and MoS.sub.2 has reinvigorated the field of 2D materials, revealing exotic phenomena at their interfaces.sup.1,2. These unique interfaces are typically constructed using mechanical or deposition-based methods to build a heterostructure one monolayer at a time.sup.2,3. By contrast, self-assembly is a scalable technique, where complex materials can selectively form in solution.sup.4-6. Here we show a synthetic strategy for the self-assembly of layered perovskite-non-perovskite heterostructures into large single crystals in aqueous solution. Using bifunctional organic molecules as directing groups, we have isolated six layered heterostructures that form as an interleaving of perovskite slabs with a different inorganic lattice, previously unknown to crystallize with perovskites. In many cases, these intergrown lattices are 2D congeners of canonical inorganic structure types. To our knowledge, these compounds are the first layered perovskite heterostructures formed using organic templates and characterized by single-crystal X-ray diffraction. Notably, this interleaving of inorganic structures can markedly transform the band structure. Optical data and first principles calculations show that substantive coupling between perovskite and intergrowth layers leads to new electronic transitions distributed across both sublattices. Given the technological promise of halide perovskites.sup.4, this intuitive synthetic route sets a foundation for the directed synthesis of richly structured complex semiconductors that self-assemble in water. Using organic molecules as directing groups, a wide range of perovskite heterostructures are shown to self-assemble in solution to yield single crystals., Author(s): Michael L. Aubrey [sup.1] , Abraham Saldivar Valdes [sup.1] , Marina R. Filip [sup.2] [sup.3] [sup.4] , Bridget A. Connor [sup.1] , Kurt P. Lindquist [sup.1] , Jeffrey B. [...]

The expansion of deformation-induced crystallization of polypropylene (PP) pipes was studied. The crystal structure and melting characteristics of the samples after expanding at different expansion strains and expansion temperatures were analyzed. The results showed that the ciystallinity was improved when the PP pipes were expanded, and the expansion effect made the crystal structure more perfect while the expanding temperature did not exceed the crystallization temperature. However, once expanding temperature exceeded crystallization temperature, some [beta] lamellae crystal were stretched and transformed into a crystals structure. It showed that the expansion effect could cause the crystal phase transformation of the sample. In addition, when the expanding strain was less than 15%, the [beta] crystal diffraction peak intensity of the sample decreased, but the a crystal diffraction peak intensity increased, and the original sparse distribution lamellae structure gradually became compact. With the expanding strain continued to increase, the oriented molecular chains underwent stress relaxation, which hindered the conversion of [beta] crystals to a crystals. The oriented crystal structure formed by the crystal phase transformation made the PP pipe have excellent tensile and impact strength. As a result, the hoop tensile strength is increased by 13%, and the impact strengths are increased by 36%. KEYWORDS expanding, phase transformation, PP pipe, [beta] crystals, 1 | INTRODUCTION As we all know, polypropylene is widely used in packaging, home appliances, and automobiles due to its good mechanical properties and easy processing and molding. [1-4] As [...]

N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide, a commercial nucleating agent, can dissolve into molten polypropylene (PP) and self-organize into needle-like crystals when the melt temperature reaches 260[degrees]C. As temperature decreases, PP molecules crystallize on the surface of the needle-like crystals with their c-axis perpendicular to the long axis of the crystal. Under a flow field in injection molding, PP chains are parallel or perpendicular to the flow direction at different depths owing to the difference in crystallization kinetics and applied shear rate in the melt, forming a plywood-like material. This unique structure can simultaneously improve the toughness and strength of plastic parts. Herein, we present a novel method of producing high-performance plastic articles based on general plastics by manipulating their morphology and structure. KEYWORDS crystal structures, injection molding, mechanical properties, orientation, poly(propylene) (PP), structure-property relations, 1 | INTRODUCTION Plywood is composed of piled veneers in which the wood fibers of adjacent piles are perpendicular to each other. This particular structure ensures that the material is [...]