Journal articles on the topic 'Bones – Molecular aspects'
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1
Safarova, S. S. "Pathogenetic aspects of bone metabolism in diabetes mellitus." Clinical Medicine (Russian Journal) 96, no. 8 (December 20, 2018): 707–12. http://dx.doi.org/10.18821/0023-2149-2018-96-8-707-712.
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Metabolic disorders caused by diabetes affect bone remodeling, alter the structure and reduce the strength of bone tissue, leading to the development of diabetic osteopathy. However, between diabetes mellitus (DM) type 1 and 2 there are noticeable differences in the effect on the bone structure, which is obviously due to the different cellular and molecular mechanisms of these processes. The density of bone tissue with DM typel decreases, which leads to an increase in the risk of fractures by 7 times. With DM type 2, bone mineral density is moderately elevated, which is expected to lead to a decrease in the incidence of osteoporotic fractures, but in fact, this index is approximately doubled. Pathophysiological mechanisms underlying osteoporotic changes in diabetes mellitus are complex and included hyperglycemia, oxidative stress and accumulation of advanced glycation endproducts that alter the properties of collagen, increase fatty infiltration of the bone marrow, release inflammatory factors and adipokines from visceral adipose tissue and potentially change the function osteoblasts. Additional factors are, some antidiabetic drugs that directly affect the metabolism of bones and minerals (such as thiazolidinediones), as well as an increased tendency to fall due to micro- and macroangiopathies, all contribute to an increased risk of low-fracture fractures in patients with diabetes mellitus.
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Maltsev, S. V., A. I. Safina, and T. V. Mihajlova. "Гипофосфатемический рахит у детей — клинические и генетические аспекты, подходы к терапии." Practical medicine 19, no. 1 (2021): 38–49. http://dx.doi.org/10.32000/2072-1757-2021-1-38-49.
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Hypophosphatemic rickets (phosphate-diabetes) is a group of diseases associated with a defect in the reabsorption of phosphates in the proximal tubules, manifested by phosphaturia, hypophosphatemia and rickets deformities of the skeleton bones. Phosphate-diabetes has different genetic variants that determine the nature and severity of clinical manifestations. X-linked dominant hypophosphatemic rickets occurs most often (in 50-90% of cases). For the diagnosis, along with clinical characteristics, an important role is assigned to the study of partial renal functions, with the determination of clearance, excreted fraction of calcium and phosphates, as well as other indicators of calcium-phosphorus metabolism. Molecular genetic research helps to determine the form of the disease. Therapy for hypophosphatemic rickets should be differentiated depending on the type of disease. The timely appointment of an adequate pathogenetic therapy helps to slow down the formation of rickety deformities of the skeleton, positive growth dynamics, and an increase in physical activity.
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Kushchayev, Sergiy V., Yevgeniya S. Kushchayeva, Sri Harsha Tella, Tetiana Glushko, Karel Pacak, and Oleg M. Teytelboym. "Medullary Thyroid Carcinoma: An Update on Imaging." Journal of Thyroid Research 2019 (July 7, 2019): 1–17. http://dx.doi.org/10.1155/2019/1893047.
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Medullary thyroid carcinoma (MTC), arising from the parafollicular C cells of the thyroid, accounts for 1–2% of thyroid cancers. MTC is frequently aggressive and metastasizes to cervical and mediastinal lymph nodes, lungs, liver, and bones. Although a number of new imaging modalities for directing the management of oncologic patients evolved over the last two decades, the clinical application of these novel techniques is limited in MTC. In this article, we review the biology and molecular aspects of MTC as an important background for the use of current imaging modalities and approaches for this tumor. We discuss the modern and currently available imaging techniques—advanced magnetic resonance imaging (MRI)-based techniques such as whole-body MRI, dynamic contrast-enhanced (DCE) technique, diffusion-weighted imaging (DWI), positron emission tomography/computed tomography (PET/CT) with 18F-FDOPA and 18F-FDG, and integrated positron emission tomography/magnetic resonance (PET/MR) hybrid imaging—for primary as well as metastatic MTC tumor, including its metastatic spread to lymph nodes and the most common sites of distant metastases: lungs, liver, and bones.
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Rice, Ritva, Aki Kallonen, Judith Cebra-Thomas, and Scott F. Gilbert. "Development of the turtle plastron, the order-defining skeletal structure." Proceedings of the National Academy of Sciences 113, no. 19 (April 25, 2016): 5317–22. http://dx.doi.org/10.1073/pnas.1600958113.
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The dorsal and ventral aspects of the turtle shell, the carapace and the plastron, are developmentally different entities. The carapace contains axial endochondral skeletal elements and exoskeletal dermal bones. The exoskeletal plastron is found in all extant and extinct species of crown turtles found to date and is synaptomorphic of the order Testudines. However, paleontological reconstructed transition forms lack a fully developed carapace and show a progression of bony elements ancestral to the plastron. To understand the evolutionary development of the plastron, it is essential to know how it has formed. Here we studied the molecular development and patterning of plastron bones in a cryptodire turtleTrachemys scripta. We show that plastron development begins at developmental stage 15 when osteochondrogenic mesenchyme forms condensates for each plastron bone at the lateral edges of the ventral mesenchyme. These condensations commit to an osteogenic identity and suppress chondrogenesis. Their development overlaps with that of sternal cartilage development in chicks and mice. Thus, we suggest that in turtles, the sternal morphogenesis is prevented in the ventral mesenchyme by the concomitant induction of osteogenesis and the suppression of chondrogenesis. The osteogenic subroutines later direct the growth and patterning of plastron bones in an autonomous manner. The initiation of plastron bone development coincides with that of carapacial ridge formation, suggesting that the development of dorsal and ventral shells are coordinated from the start and that adopting an osteogenesis-inducing and chondrogenesis-suppressing cell fate in the ventral mesenchyme has permitted turtles to develop their order-specific ventral morphology.
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Abe, Shinichi, and Masahito Yamamoto. "Factors Involved in Morphogenesis in the Muscle–Tendon–Bone Complex." International Journal of Molecular Sciences 22, no. 12 (June 14, 2021): 6365. http://dx.doi.org/10.3390/ijms22126365.
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A decline in the body’s motor functions has been linked to decreased muscle mass and function in the oral cavity and throat; however, aging of the junctions of the muscles and bones has also been identified as an associated factor. Basic and clinical studies on the muscles, tendons and bones, each considered independently, have been published. In recent years, however, research has focused on muscle attachment as the muscle–tendon–bone complex from various perspectives, and there is a growing body of knowledge on SRY-box9 (Sox9) and Mohawk(Mkx), which has been identified as a common controlling factor and a key element. Myostatin, a factor that inhibits muscle growth, has been identified as a potential key element in the mechanisms of lifetime structural maintenance of the muscle–tendon–bone complex. Findings in recent studies have also uncovered aspects of the mechanisms of motor organ complex morphostasis in the superaged society of today and will lay the groundwork for treatments to prevent motor function decline in older adults.
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Jentgen-Ceschino, Benjamin, Koen Stein, and Valentin Fischer. "Case study of radial fibrolamellar bone tissues in the outer cortex of basal sauropods." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1793 (January 13, 2020): 20190143. http://dx.doi.org/10.1098/rstb.2019.0143.
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The histology of sauropod long bones often appears uniform and conservative along their evolutionary tree. One of the main aspects of their bone histology is to exhibit a fibrolamellar complex in the cortex of their long bones. Here, we report another bone tissue, the radial fibrolamellar bone (RFB), in the outer cortex of the humeri of a young adult cf. Isanosaurus (Early to Late Jurassic, Thailand) and an adult Spinophorosaurus nigerensis (Early to Middle Jurassic, Niger) that do not exhibit any pathological feature on the bone surface. Its location within the cortex is unexpected, because RFB is a rapidly deposited bone tissue that would rather be expected early in the ontogeny. A palaeopathological survey was conducted for these sampled specimens. Observed RFB occurrences are regarded as spiculated periosteal reactive bone, which is an aggressive form of periosteal reaction. A ‘hair-on-end’ pattern of neoplasmic origin (resembling a Ewing's sarcoma) is favoured for cf. Isanosaurus , while a sunburst pattern of viral or neoplasmic origin (resembling an avian osteopetrosis or haemangioma) is favoured for Spinophorosaurus . This study highlights the importance of bone histology in assessing the frequency and nature of palaeopathologies. This article is part of the theme issue ‘Vertebrate palaeophysiology’.
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Richardson, Jo, Takanori Shono, Masataka Okabe, and Anthony Graham. "The presence of an embryonic opercular flap in amniotes." Proceedings of the Royal Society B: Biological Sciences 279, no. 1727 (June 2011): 224–29. http://dx.doi.org/10.1098/rspb.2011.0740.
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The operculum is a large flap consisting of several flat bones found on the side of the head of bony fish. During development, the opercular bones form within the second pharyngeal arch, which expands posteriorly and comes to cover the gill-bearing arches. With the evolution of the tetrapods and the assumption of a terrestrial lifestyle, it was believed that the operculum was lost. Here, we demonstrate that an embryonic operculum persists in amniotes and that its early development is homologous with that of teleosts. As in zebrafish, the second pharyngeal arch of the chick embryo grows disproportionately and comes to cover the posterior arches. We show that the developing second pharyngeal arch in both chick and zebrafish embryos express orthologous genes and require shh signalling for caudal expansion. In amniotes, however, the caudal edge of the expanded second arch fuses to the surface of the neck. We have detailed how this process occurs and also demonstrated a requirement for thyroid signalling here. Our results thus demonstrate the persistence of an embryonic opercular flap in amniotes, that its fusion mirrors aspects of amphibian metamorphosis and gives insights into the origin of branchial cleft anomalies in humans.
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Gentile, Cristina, and Francesco Chiarelli. "Rickets in Children: An Update." Biomedicines 9, no. 7 (June 27, 2021): 738. http://dx.doi.org/10.3390/biomedicines9070738.
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Rickets refers to a deficient mineralization of the growth plate cartilage, predominantly affecting longer bones. Despite the fact that preventive measures are available, it is still a common disease worldwide; nutritional rickets, due to vitamin D deficiency or dietary calcium inadequate intake, remains the most common form. Medical history, physical examination, radiologic features and biochemical tests are essential for diagnosis. Although recent studies suggest hypophosphatemia as the leading alteration, rickets is classically divided into two categories: calcipenic rickets and phosphopenic rickets. Knowledge of this categorization and of respective clinical and laboratory features is essential for rapid diagnosis and correct management. The aim of this review is to analyze the epidemiological, pathogenetic, clinical, and therapeutic aspects of the different forms of rickets, describing the novelties on this “long-lived” disease.
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Iwaszczuk, Urszula, Justyna Niderla-Bielińska, and Aneta Ścieżyńska. "Kings and peasants from El-Zuma/El-Detti microregion in the Early Makurian period. Economic aspects of animal bones from funerary contexts." PLOS ONE 14, no. 2 (February 15, 2019): e0212423. http://dx.doi.org/10.1371/journal.pone.0212423.
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YANG, XIUPING, FENGJU SUN, LONGTAO WANG, CHUNQIU ZHANG, and XIZHENG ZHANG. "SOLUTE TRANSPORT IN ARTICULAR CARTILAGE UNDER ROLLING-COMPRESSION LOAD." Journal of Mechanics in Medicine and Biology 19, no. 06 (September 2019): 1950054. http://dx.doi.org/10.1142/s0219519419500544.
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Solute transport is one of the important aspects involved in maintaining the physiological activity of tissues. The mechanical environment drives nutrition in and waste out in articular cartilage due to its avascularity, which plays a key role in the biological activity of articular cartilage. The human knee joint motion is a complex interaction between different bones including relative rolling and/or sliding movements. Rolling-compression process is a typical physiological load in knee joint motion. To investigate solute transport behavior in articular cartilage under rolling-compression load, fluorescence tracers with molecular weights of 40kDa and 0.43kDa were used respectively to mark the transport in fresh articular cartilage of mature pigs. Solute fluorescence intensity changing with time and depth of cartilage layer was measured under rolling-compression load and static state, respectively, and the distribution of corresponding relative concentration was calculated by the fluorescence microscope imaging method. The experiment results show that the solute relative concentration in articular cartilage under rolling-compression load increases significantly, even up to 62.4%, comparing with that under static state, and the changes of concentration vary in different layers and that small molecular weight solute is easier to transport than relatively large molecular weight solute in articular cartilage. Therefore, rolling-compression load can promote the solute transport in cartilage, and the mechanical loading may have application in functional cartilage tissue engineering.
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Bishop, Peter J., Scott A. Hocknull, Christofer J. Clemente, John R. Hutchinson, Andrew A. Farke, Belinda R. Beck, Rod S. Barrett, and David G. Lloyd. "Cancellous bone and theropod dinosaur locomotion. Part I—an examination of cancellous bone architecture in the hindlimb bones of theropods." PeerJ 6 (October 31, 2018): e5778. http://dx.doi.org/10.7717/peerj.5778.
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This paper is the first of a three-part series that investigates the architecture of cancellous (‘spongy’) bone in the main hindlimb bones of theropod dinosaurs, and uses cancellous bone architectural patterns to infer locomotor biomechanics in extinct non-avian species. Cancellous bone is widely known to be highly sensitive to its mechanical environment, and has previously been used to infer locomotor biomechanics in extinct tetrapod vertebrates, especially primates. Despite great promise, cancellous bone architecture has remained little utilized for investigating locomotion in many other extinct vertebrate groups, such as dinosaurs. Documentation and quantification of architectural patterns across a whole bone, and across multiple bones, can provide much information on cancellous bone architectural patterns and variation across species. Additionally, this also lends itself to analysis of the musculoskeletal biomechanical factors involved in a direct, mechanistic fashion.On this premise, computed tomographic and image analysis techniques were used to describe and analyse the three-dimensional architecture of cancellous bone in the main hindlimb bones of theropod dinosaurs for the first time. A comprehensive survey across many extant and extinct species is produced, identifying several patterns of similarity and contrast between groups. For instance, more stemward non-avian theropods (e.g. ceratosaurs and tyrannosaurids) exhibit cancellous bone architectures more comparable to that present in humans, whereas species more closely related to birds (e.g. paravians) exhibit architectural patterns bearing greater similarity to those of extant birds. Many of the observed patterns may be linked to particular aspects of locomotor biomechanics, such as the degree of hip or knee flexion during stance and gait. A further important observation is the abundance of markedly oblique trabeculae in the diaphyses of the femur and tibia of birds, which in large species produces spiralling patterns along the endosteal surface. Not only do these observations provide new insight into theropod anatomy and behaviour, they also provide the foundation for mechanistic testing of locomotor hypotheses via musculoskeletal biomechanical modelling.
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Kubicek, Jan, Filip Tomanec, Martin Cerny, Dominik Vilimek, Martina Kalova, and David Oczka. "Recent Trends, Technical Concepts and Components of Computer-Assisted Orthopedic Surgery Systems: A Comprehensive Review." Sensors 19, no. 23 (November 27, 2019): 5199. http://dx.doi.org/10.3390/s19235199.
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Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.
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Sánchez-Gómez, Rubén, Ricardo Becerro de Bengoa-Vallejo, Marta Elena Losa-Iglesias, César Calvo-Lobo, Carlos Romero-Morales, Eva María Martínez-Jiménez, Patricia Palomo-López, and Daniel López-López. "Heel Height as an Etiology of Hallux Abductus Valgus Development: An electromagnetic Static and Dynamic First Metatarsophalangeal Joint Study." Sensors 19, no. 6 (March 16, 2019): 1328. http://dx.doi.org/10.3390/s19061328.
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Background: Hallux abductus valgus (HAV) is a forefoot condition produced by extrinsic and intrinsic factors. Shoes with a high heel height and a typical narrow tip toe box can induce deviations in both the proximal phalanx of the hallux (PPH) and the first metatarsal (IMTT) bones. Nevertheless, the isolated role of heel height remains unclear in the development of HAV pathology. Objectives: The goal was to determine if the heel height increase of shoes without a narrow box toe could augment the PPH and IMTT deviation in frontal, sagittal, and transverse planes toward the first metatarsophalangeal joint (MPJ) and the first metatarsocuneiform joint (MCJ), respectively, during static and dynamic conditions in relation to precursor movements of HAV. Methods: Women with an average age of 25.10 ± 4.67 years were recruited in this cross-sectional study to assess the three planes of motion of PPH and IMTT while wearing high heels with heights at 3, 6, 9 cm and unshod conditions via sandals. The measurements used an electromagnetic goniometer device with sensors placed on medial aspects of the PPH and IMTT bones under static and dynamic conditions. Results: Wearing shoes with a 6 cm heel in dynamic condition may increase the PPH valgus and abduction deviation from 3.15 ± 0.10° to 3.46 ± 0.05° (p < 0.05) and from 1.35 ± 0.28° to 1.69 ± 0.30° (p < 0.001), respectively. In addition, a PPH abduction increase from 1.01 ± 0.36° to 1.31 ± 0.46° (p < 0.05) after wearing shoes with a 6 cm heel height was observed under static conditions. Conclusions: Wearing shoes with a heel height of 6 cm without a narrow box toe interference may produce PPH abduction and valgus deviations related to HAV formation.
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Andrzejczuk-Hybel, J., K. Bartoszewicz, T. Bernacka, U. Dałek, A. Kusińska, W. Liss, and J. Kączkowski. "Some methodical aspects in investigations on wheat gluten." Acta Agrobotanica 25, no. 2 (2015): 161–70. http://dx.doi.org/10.5586/aa.1972.008.
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3 M urea has been shown to cause considerable, and only partially reversible conformational changes of gluten molecules. Homogenization has proved to act mechanically, breaking down some molecular bonds. No structural changes could be observed during freeze drying gluten, as well as after brief heating of its acetic acid extracts.
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Brönnimann, David, Johannes Wimmer, Milena Müller-Kissing, Barbara Stopp, Hannele Rissanen, and Norbert Spichtig. "One man’s trash is another man’s treasure. Interdisciplinary examination of taphonomic aspects of ceramic sherds, animal bones and sediments from the La Tène period settlement at Basel-Gasfabrik." PLOS ONE 15, no. 7 (July 27, 2020): e0236272. http://dx.doi.org/10.1371/journal.pone.0236272.
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Riga, Alessandro, Marco Boggioni, Andrea Papini, Costantino Buzi, Antonio Profico, Fabio Di Vincenzo, Damiano Marchi, Jacopo Moggi-Cecchi, and Giorgio Manzi. "In situ observations on the dentition and oral cavity of the Neanderthal skeleton from Altamura (Italy)." PLOS ONE 15, no. 12 (December 2, 2020): e0241713. http://dx.doi.org/10.1371/journal.pone.0241713.
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The Neanderthal specimen from Lamalunga Cave, near Altamura (Apulia, Italy), was discovered during a speleological survey in 1993. The specimen is one of the most complete fossil hominins in Europe and its state of preservation is exceptional, although it is stuck in calcareous concretions and the bones are mostly covered by calcite depositions. Nevertheless, it is possible to carry out some observations on craniodental features that have not previously been described. In this work, we present an account of the oral cavity, made possible by the use of a videoscope, which allowed us to reach some hidden parts of the mandible and palate. This is the first detailed overview of the teeth and maxillary bones of the Neanderthal skeleton from Altamura. The dentition is almost complete. However, two teeth (upper right P3 and upper left M1) were lost ante mortem and four teeth (lower right I1 and P3 and lower left I1 and I2) were lost most probably post mortem. Dental wear is marked. The erupted M3s and the inversion of the compensating curve of Wilson in the M1s and M2s but not in the M3s suggest that the individual is fully adult, but not old. Although most of the teeth have their roots exposed for several millimeters, the periodontal bone appears to be in good condition overall, except in correspondence of the two ante-mortem tooth losses. X-rays of the anterior teeth show a periapical lesion, probably linked to the advanced dental wear. We also observed a weak expression of taurodontism in the posterior dentition and the presence of a retromolar space, features consistent with an attribution to the Neanderthal hypodigm; this attribution is also supported by aspects of the cranial morphology, the morphometric analysis of the scapula and preliminary mtDNA data. There is also a well-developed palatine torus, to the best of our knowledge a feature not previously described in Neanderthals.
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Evers, Serjoscha W., Christian Foth, and Oliver W. M. Rauhut. "Notes on the cheek region of the Late Jurassic theropod dinosaur Allosaurus." PeerJ 8 (February 7, 2020): e8493. http://dx.doi.org/10.7717/peerj.8493.
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Allosaurus, from the Late Jurassic of North America and Europe, is a model taxon for Jurassic basal tetanuran theropod dinosaurs. It has achieved an almost iconic status due to its early discovery in the late, 19th century, and due to the abundance of material from the Morrison Formation of the western U.S.A., making Allosaurus one of the best-known theropod taxa. Despite this, various aspects of the cranial anatomy of Allosaurus are surprisingly poorly understood. Here, we discuss the osteology of the cheek region, comprised by the jugal, maxilla, and lacrimal. This region of the skull is of importance for Allosaurus taxonomy and phylogeny, particularly because Allosaurus has traditionally been reconstructed with an unusual cheek configuration, and because the European species Allosaurus europaeus has been said to be different from North American material in the configuration of these bones. Based on re-examination of articulated and disarticulated material from a number of repositories, we show that the jugal participates in the antorbital fenestra, contradicting the common interpretation. The jugal laterally overlies the lacrimal, and forms an extended antorbital fossa with this bone. Furthermore, we document previously unrecorded pneumatic features of the jugal of Allosaurus.
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Yochelis, Shira, Eran Katzir, Yoav Kalcheim, Vitaly Gutkin, Oded Millo, and Yossi Paltiel. "Formation of Au-Silane Bonds." Journal of Nanotechnology 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/903761.
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Many intriguing aspects of molecular electronics are attributed to organic-inorganic interactions, yet charge transfer through such junctions still requires fundamental study. Recently, there is a growing interest in anchoring groups, which considered dominating the charge transport. With this respect, we choose to investigate self-assembly of disilane molecules sandwiched between gold surface and gold nanoparticles. These assemblies are found to exhibit covalent bonds not only between the anchoring Si groups and the gold surfaces but also in plane crosslinks that increase the monolayer stability. Finally, using scanning tunneling spectroscopy we demonstrate that the disilane molecules provide strong electrical coupling between the Au nanoparticles and a superconductor substrate.
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Hearn, Les, and Amanda C. de C. Williams. "Pain in dinosaurs: what is the evidence?" Philosophical Transactions of the Royal Society B: Biological Sciences 374, no. 1785 (September 23, 2019): 20190370. http://dx.doi.org/10.1098/rstb.2019.0370.
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How far back can we trace behaviour associated with pain? Behaviour is not preserved in the palaeontological record, so, for dinosaurs, we are restricted to what we can deduce from fossilized bones and tracks. This review is a thought experiment using circumstantial evidence from dinosaur fossils and from the behaviour of their extant relatives to describe probable responses of dinosaurs to serious injuries. Searches yielded 196 papers and chapters with: reports of healed serious injuries, and limping gait and injured feet in trackways; information about physiology and behaviour relevant to healing; evidence of evolutionary connections with birds and crocodilians, and their behaviour; and information about relevant aspects of evolution. Clearly, many dinosaurs survived injuries that would have seriously hampered mobility, impairing hunting or escape from predators, and affecting social interactions. Recovery from severe injuries implies pain-mediated responses. Rates of healing seem faster than for other reptiles, possibily aided by warm-bloodedness. Nesting was often communal, raising the possibility of parental and group protection for injured young. The existence of family groups, packs or herds raises the possibility of protection or feeding from pack kills. This is the first study, to our knowledge, of possible pain behaviour and responses to injury in dinosaurs. This article is part of the Theo Murphy meeting issue ‘Evolution of mechanisms and behaviour important for pain’.
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McCurry, Matthew R., Alistair R. Evans, Erich M. G. Fitzgerald, Justin W. Adams, Philip D. Clausen, and Colin R. McHenry. "The remarkable convergence of skull shape in crocodilians and toothed whales." Proceedings of the Royal Society B: Biological Sciences 284, no. 1850 (March 8, 2017): 20162348. http://dx.doi.org/10.1098/rspb.2016.2348.
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The striking resemblance of long-snouted aquatic mammals and reptiles has long been considered an example of morphological convergence, yet the true cause of this similarity remains untested. We addressed this deficit through three-dimensional morphometric analysis of the full diversity of crocodilian and toothed whale (Odontoceti) skull shapes. Our focus on biomechanically important aspects of shape allowed us to overcome difficulties involved in comparing mammals and reptiles, which have fundamental differences in the number and position of skull bones. We examined whether diet, habitat and prey size correlated with skull shape using phylogenetically informed statistical procedures. Crocodilians and toothed whales have a similar range of skull shapes, varying from extremely short and broad to extremely elongate. This spectrum of shapes represented more of the total variation in our dataset than between phylogenetic groups. The most elongate species (river dolphins and gharials) are extremely convergent in skull shape, clustering outside of the range of the other taxa. Our results suggest the remarkable convergence between long-snouted river dolphins and gharials is driven by diet rather than physical factors intrinsic to riverine environments. Despite diverging approximately 288 million years ago, crocodilians and odontocetes have evolved a remarkably similar morphological solution to feeding on similar prey.
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Baab, Karen L. "Reconstructing cranial evolution in an extinct hominin." Proceedings of the Royal Society B: Biological Sciences 288, no. 1943 (January 20, 2021): 20202604. http://dx.doi.org/10.1098/rspb.2020.2604.
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Homo erectus is the first hominin species with a truly cosmopolitan distribution and resembles recent humans in its broad spatial distribution. The microevolutionary events associated with dispersal and local adaptation may have produced similar population structure in both species. Understanding the evolutionary population dynamics of H. erectus has larger implications for the emergence of later Homo lineages in the Middle Pleistocene. Quantitative genetics models provide a means of interrogating aspects of long-standing H. erectus population history narratives. For the current study, cranial fossils were sorted into six major palaeodemes from sites across Africa and Asia spanning 1.8–0.1 Ma. Three-dimensional shape data from the occipital and frontal bones were used to compare intraspecific variation and test evolutionary hypotheses. Results indicate that H. erectus had higher individual and group variation than Homo sapiens , probably reflecting different levels of genetic diversity and population history in these spatially disperse species. This study also revealed distinct evolutionary histories for frontal and occipital bone shape in H. erectus , with a larger role for natural selection in the former. One scenario consistent with these findings is climate-driven facial adaptation in H. erectus , which is reflected in the frontal bone through integration with the orbits.
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Jacobs, Megan L., and David M. Martill. "A new ophthalmosaurid ichthyosaur from the Upper Jurassic (Early Tithonian) Kimmeridge Clay of Dorset, UK, with implications for Late Jurassic ichthyosaur diversity." PLOS ONE 15, no. 12 (December 9, 2020): e0241700. http://dx.doi.org/10.1371/journal.pone.0241700.
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A new ophthalmosaurid ichthyosaur, Thalassodraco etchesi gen. et sp. nov., from the Upper Jurassic Kimmeridge Clay Formation of Dorset, UK is described. The specimen, a partial, articulated skull and anterior thorax in the Etches Collection of Kimmeridge, Dorset, is exceptionally well preserved on a slab of laminated coccolith limestone and has been expertly prepared. It comprises a near complete skull in articulation with associated anterior vertebral column and dorsal ribs, complete pectoral girdle, fully exposed left forelimb, and some elements of the right forelimb. Other elements present, including an ischiopubis are preserved on separate slabs. Presumed rapid burial of the anterior portion of the specimen in the coccolith substrate has preserved a number of ossified ligaments lying across the vertebral column and associated ribs as well as stomach contents and decayed internal organs. Aspects of the dentition, skull roof bones and the forelimb configuration distinguishes the new specimen from previously described Late Jurassic ichthyosaurs. Autopmorphies for T. etchesi include a large rounded protuberance on the supratemporal bone; a thin L-shaped lachrymal, with a steeply curved posterior border; ~ 70 teeth on the upper tooth row, and deep anterior dorsal ribs. A well resolved phylogenetic analysis shows T. etchesi as a member of a basal clade within Ophthalmosauridae comprising Nannopterygius, Gengasaurus, Paraophthalmosaurus and Thalassodraco. The new specimen adds to the diversity of the Ichthyopterygia of the Kimmeridge Clay Formation and emphasises the important contribution of amateur collectors in palaeontology.
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Esrafili, Mehdi, and Parisasadat Mousavian. "Strong Tetrel Bonds: Theoretical Aspects and Experimental Evidence." Molecules 23, no. 10 (October 15, 2018): 2642. http://dx.doi.org/10.3390/molecules23102642.
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In recent years, noncovalent interactions involving group-14 elements of the periodic table acting as a Lewis acid center (or tetrel-bonding interactions) have attracted considerable attention due to their potential applications in supramolecular chemistry, material science and so on. The aim of the present study is to characterize the geometry, strength and bonding properties of strong tetrel-bond interactions in some charge-assisted tetrel-bonded complexes. Ab initio calculations are performed, and the results are supported by the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) approaches. The interaction energies of the anionic tetrel-bonded complexes formed between XF3M molecule (X=F, CN; M=Si, Ge and Sn) and A− anions (A−=F−, Cl−, Br−, CN−, NC− and N3−) vary between −16.35 and −96.30 kcal/mol. The M atom in these complexes is generally characterized by pentavalency, i.e., is hypervalent. Moreover, the QTAIM analysis confirms that the anionic tetrel-bonding interaction in these systems could be classified as a strong interaction with some covalent character. On the other hand, it is found that the tetrel-bond interactions in cationic tetrel-bonded [p-NH3(C6H4)MH3]+···Z and [p-NH3(C6F4)MH3]+···Z complexes (M=Si, Ge, Sn and Z=NH3, NH2CH3, NH2OH and NH2NH2) are characterized by a strong orbital interaction between the filled lone-pair orbital of the Lewis base and empty BD*M-C orbital of the Lewis base. The substitution of the F atoms in the benzene ring provides a strong orbital interaction, and hence improved tetrel-bond interaction. For all charge-assisted tetrel-bonded complexes, it is seen that the formation of tetrel-bond interaction is accompanied bysignificant electron density redistribution over the interacting subunits. Finally, we provide some experimental evidence for the existence of such charge-assisted tetrel-bond interactions in crystalline phase.
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Holland, Brayden, Phil R. Bell, Federico Fanti, Samantha M. Hamilton, Derek W. Larson, Robin Sissons, Corwin Sullivan, Matthew J. Vavrek, Yanyin Wang, and Nicolás E. Campione. "Taphonomy and taxonomy of a juvenile lambeosaurine (Ornithischia: Hadrosauridae) bonebed from the late Campanian Wapiti Formation of northwestern Alberta, Canada." PeerJ 9 (May 4, 2021): e11290. http://dx.doi.org/10.7717/peerj.11290.
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Hadrosaurid (duck-billed) dinosaur bonebeds are exceedingly prevalent in upper Cretaceous (Campanian–Maastrichtian) strata from the Midwest of North America (especially Alberta, Canada, and Montana, U.S.A) but are less frequently documented from more northern regions. The Wapiti Formation (Campanian–Maastrichtian) of northwestern Alberta is a largely untapped resource of terrestrial palaeontological information missing from southern Alberta due to the deposition of the marine Bearpaw Formation. In 2018, the Boreal Alberta Dinosaur Project rediscovered the Spring Creek Bonebed, which had been lost since 2002, along the northern bank of the Wapiti River, southwest of Grande Prairie. Earlier excavations and observations of the Spring Creek Bonebed suggested that the site yielded young hadrosaurines. Continued work in 2018 and 2019 recovered ~300 specimens that included a minimum of eight individuals, based on the number of right humeri. The morphology of several recovered cranial elements unequivocally supports lambeosaurine affinities, making the Spring Creek sample the first documented occurrence of lambeosaurines in the Wapiti Formation. The overall size range and histology of the bones found at the site indicate that these animals were uniformly late juveniles, suggesting that age segregation was a life history strategy among hadrosaurids. Given the considerable size attained by the Spring Creek lambeosaurines, they were probably segregated from the breeding population during nesting or caring for young, rather than due to different diet and locomotory requirements. Dynamic aspects of life history, such as age segregation, may well have contributed to the highly diverse and cosmopolitan nature of Late Cretaceous hadrosaurids.
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Petersen, Richard C. "Computational conformational antimicrobial analysis developing mechanomolecular theory for polymer biomaterials in materials science and engineering." International Journal of Computational Materials Science and Engineering 03, no. 01 (March 2014): 1450003. http://dx.doi.org/10.1142/s2047684114500031.
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Single-bond rotations or pyramidal inversions tend to either hide or expose relative energies that exist for atoms with nonbonding lone-pair electrons. Availability of lone-pair electrons depends on overall molecular electron distributions and differences in the immediate polarity of the surrounding pico/nanoenvironment. Stereochemistry three-dimensional aspects of molecules provide insight into conformations through single-bond rotations with associated lone-pair electrons on oxygen atoms in addition to pyramidal inversions with nitrogen atoms. When electrons are protected, potential energy is sheltered toward an energy minimum value to compatibilize molecularly with nonpolar environments. When electrons are exposed, maximum energy is available toward polar environment interactions. Computational conformational analysis software calculated energy profiles that exist during specific oxygen ether single-bond rotations with easy-to-visualize three-dimensional models for the trichlorinated bisaromatic ether triclosan antimicrobial polymer additive. As shown, fluctuating alternating bond rotations can produce complex interactions between molecules to provide entanglement strength for polymer toughness or alternatively disrupt weak secondary bonds of attraction to lower resin viscosity for new additive properties with nonpolar triclosan as a hydrophobic toughening/wetting agent. Further, bond rotations involving lone-pair electrons by a molecule at a nonpolar-hydrocarbon-membrane/polar-biologic-fluid interface might become sufficiently unstable to provide free mechanomolecular energies to disrupt weaker microbial membranes, for membrane transport of molecules into cells, provide cell signaling/recognition/defense and also generate enzyme mixing to speed reactions.
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Bishop, Peter J., Scott A. Hocknull, Christofer J. Clemente, John R. Hutchinson, Andrew A. Farke, Rod S. Barrett, and David G. Lloyd. "Cancellous bone and theropod dinosaur locomotion. Part III—Inferring posture and locomotor biomechanics in extinct theropods, and its evolution on the line to birds." PeerJ 6 (October 31, 2018): e5777. http://dx.doi.org/10.7717/peerj.5777.
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This paper is the last of a three-part series that investigates the architecture of cancellous bone in the main hindlimb bones of theropod dinosaurs, and uses cancellous bone architectural patterns to infer locomotor biomechanics in extinct non-avian species. Cancellous bone is highly sensitive to its prevailing mechanical environment, and may therefore help further understanding of locomotor biomechanics in extinct tetrapod vertebrates such as dinosaurs. Here in Part III, the biomechanical modelling approach derived previously was applied to two species of extinct, non-avian theropods, Daspletosaurus torosus and Troodon formosus. Observed cancellous bone architectural patterns were linked with quasi-static, three-dimensional musculoskeletal and finite element models of the hindlimb of both species, and used to derive characteristic postures that best aligned continuum-level principal stresses with cancellous bone fabric. The posture identified for Daspletosaurus was largely upright, with a subvertical femoral orientation, whilst that identified for Troodon was more crouched, but not to the degree observed in extant birds. In addition to providing new insight on posture and limb articulation, this study also tested previous hypotheses of limb bone loading mechanics and muscular control strategies in non-avian theropods, and how these aspects evolved on the line to birds. The results support the hypothesis that an upright femoral posture is correlated with bending-dominant bone loading and abduction-based muscular support of the hip, whereas a crouched femoral posture is correlated with torsion-dominant bone loading and long-axis rotation-based muscular support. Moreover, the results of this study also support the inference that hindlimb posture, bone loading mechanics and muscular support strategies evolved in a gradual fashion along the line to extant birds.
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Moore, Andrew J., Jinyou Mo, James M. Clark, and Xing Xu. "Cranial anatomy of Bellusaurus sui (Dinosauria: Eusauropoda) from the Middle-Late Jurassic Shishugou Formation of northwest China and a review of sauropod cranial ontogeny." PeerJ 6 (June 1, 2018): e4881. http://dx.doi.org/10.7717/peerj.4881.
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Bellusaurus sui is an enigmatic sauropod dinosaur from the Middle-Late Jurassic Shishugou Formation of northwest China. Bellusaurus is known from a monospecific bonebed preserving elements from more than a dozen juvenile individuals, including numerous bones of the skull, providing rare insight into the cranial anatomy of juvenile sauropods. Here, we present a comprehensive description of the cranial anatomy of Bellusaurus, supplementing the holotypic cranial material with additional elements recovered from recent joint Sino-American field expeditions. Bellusaurus is diagnosed by several unique autapomorphies, including a neurovascular foramen piercing the ascending process of the maxilla at midheight, the frontal process of the nasal extending farther posteriorly onto the frontal than the prefrontal, and U-shaped medial and lateral notches in the posterior margin of the ventral process of the squamosal. Several features identified here, including a preantorbital opening in the maxilla, a stepped dorsal margin of the vomerine process of the pterygoid, and the partitioning of the dorsal midline endocranial fossae associated with the dural venous sinuses into anterior and posterior components by a transverse ridge of the parietal, are consistent with recent phylogenetic hypotheses that recover Bellusaurus as a basal macronarian or close relative of Neosauropoda. We review the current state of knowledge of sauropod cranial ontogeny, placing several aspects of the cranial anatomy of Bellusaurus in an ontogenetic context and providing explicit hypotheses of ontogenetic transformations that can be tested by future discoveries of ontogenetic variants of sauropod skulls. While scoring ontogenetically variable characters as unknown may help to alleviate the biasing effects of ontogeny on the phylogenetic position of juvenile specimens, we caution that this approach may remove phylogenetically informative character information, and argue that inference methods that are known to be less sensitive to homoplasy than equal weights parsimony (i.e., implied weights parsimony; Bayesian approaches) should also be employed.
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Sugawara, André Tadeu, Milton Seigui Oshiro, Eduardo Inglez Yamanaka, Ronaldo Meneghetti, Dayrin Vanessa Tarazona Carvajal, Leandro Ryuchi Iuamoto, and Linamara Rizzo Battistella. "Half man, half prosthesis: the rehabilitation of people with hemicorporectomy – case series." F1000Research 10 (April 19, 2021): 298. http://dx.doi.org/10.12688/f1000research.51636.1.
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Hemicorporectomy is a procedure where the lumbar spine and spinal cord, pelvic bones and contents, lower extremities and external genitalia are surgically removed. The rehabilitation process, in addition to being prolonged and costly, is challenging. This article reports the rehabilitation process for hemicorporectomy and shows the innovative solutions for mobility for this disability for two cases of paraplegic patients: case 1 due to traumatic spinal cord injury due to firearm injury and case 2 due to lumbosacral myelomeningocele. They presented chronic pressure ulcer which evolved to neoplastic transformation. (squamous cell carcinoma - Marjolin's ulcer). The cases were submitted to L4 hemicorporectomy and were rehabilitated to ensure the right to mobility independence for activities of daily living; social inclusion; prevention of comorbidities and pluralization of disabilities. The rehabilitation involved the elaboration of a new prosthesis for the hemibody and improvement of functional capacity, within a gain of 6 - 11 points in the Functional Independence Measure (FIM). The principal changes happened in social interaction, locomotion and transfers to a bed/chair and toilet. Despite the body transformation, patients show gains in quality of life mainly for the social domain of World Health Organization Quality of Life instrument-brief version (WHOQOL-bref). In general, there is an increase in the scores of this instrument from 1.78% -19.25%. The evolution of social inclusion through the International Classification of Functioning, Disability and Health (ICF) reveals that patients are able to resume social, working, academic-professional life and recreation and leisure activities, reducing the number of severe and complete qualifiers from 90.91 to 60% when using the products appropriate assistive devices. Hemicorporectomy can be a therapeutic option for those in need, as it provides functionality without the need for caregivers and resumes educational, professional, economic and social aspects with gains in quality of life.
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Liu, Jia-Bao, Hani Shaker, Imran Nadeem, and Muhammad Hussain. "Topological Aspects of Boron Nanotubes." Advances in Materials Science and Engineering 2018 (July 4, 2018): 1–11. http://dx.doi.org/10.1155/2018/5729291.
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The degree-based topological indices are used to correlate the physical and chemical properties of a molecule with its chemical structure. Boron nanotubular structures are high-interest materials due to the presence of multicenter bonds and have novel electronic properties. These materials have some important issues in nanodevice applications like mechanical and thermal stability. Therefore, they require theoretical studies on the other properties. In this paper, we present certain degree-based topological indices such as ABC, the fourth ABC, GA, and the fifth GA indices for boron triangular and boron-α nanotubes.
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Butovskii, Mikhail V., and Rhett Kempe. "Rare earth–metal bonding in molecular compounds: recent advances, challenges, and perspectives." New Journal of Chemistry 39, no. 10 (2015): 7544–58. http://dx.doi.org/10.1039/c5nj00802f.
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In this review, all structurally authenticated molecular compounds with direct bonds between rare earth metals and transition or main group metals are summarized. Novel aspects of their syntheses, properties and reactivities are highlighted.
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Quiclet-Sire, Béatrice, and Samir Z. Zard. "Some aspects of radical cascade and relay reactions." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, no. 2200 (April 2017): 20160859. http://dx.doi.org/10.1098/rspa.2016.0859.
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The ability to create carbon–carbon bonds is at the heart of organic synthesis. Radical processes are particularly apt at creating such bonds, especially in cascade or relay sequences where more than one bond is formed, allowing for a rapid assembly of complex structures. In the present brief overview, examples taken from the authors' laboratory will serve to illustrate the strategic impact of radical-based approaches on synthetic planning. Transformations involving nitrogen-centred radicals, electron transfer from metallic nickel and the reversible degenerative exchange of xanthates will be presented and discussed. The last method has proved to be a particularly powerful tool for the intermolecular creation of carbon–carbon bonds by radical additions even to unactivated alkenes. Various functional groups can be brought into the same molecule in a convergent manner and made to react together in order to further increase the structural complexity. One important benefit of this chemistry is the so-called RAFT/MADIX technology for the manufacture of block copolymers of almost any desired architecture.
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Abedini, Mohamood, Mohammad Izadyar, and Ali Nakhaeipour. "Different Aspects of Single Wall Carbon Nanotube Functionalization by Aniline Adsorption; Quantum Mechanics/Molecular Mechanics Study." Journal of Nano Research 32 (May 2015): 1–16. http://dx.doi.org/10.4028/www.scientific.net/jnanor.32.1.
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In this research, kinetics and mechanism of aniline adsorption on different single-walled carbon nanotubes (SWCNT) was investigated, using 2-layer ONIOM (Our own N-layered Integrated molecular Orbital and molecular Mechanics) method at the ONIOM (B3LYP/6-31G (d);UFF) level. Various orientations of aniline relative to the carbon nanotube surface were investigated. To investigate the adsorption of aniline, three models including open-ended (model 1), cap-ended (model 2) and 1-cap-ended (model 3) SWCNT have been modeled. Calculated activation energies of adsorption showed that model 2 has the lowest activation energy of 40.8 kcal.mol-1. Natural bond orbital and frontier molecular orbital analysis confirmed the charge transfer from the aniline to the SWCNT. Density of states analysis showed that Fermi level is shifted towards the positive values after aniline adsorption which confirmed the effective interactions between the aniline and the SWCNT. According to the quantum theory of atoms in molecules studies, new bonds formed between the SWCNT and aniline which possess a covalence nature. Finally, based on the quantum reactivity indices, new linear correlations between the chemical hardness, charge transfer and activation energy and the inverse relationship of the electrophilic property and chemical electronic potential in the functionalized carbon nanotubes were obtained. Wiberg bond index calculations show that this reaction is carried out through an asynchronous concerted mechanism. Asynchronicity value in the case of model 2 is higher than other models.
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Watanabe, Nozomi, Keishi Suga, and Hiroshi Umakoshi. "Functional Hydration Behavior: Interrelation between Hydration and Molecular Properties at Lipid Membrane Interfaces." Journal of Chemistry 2019 (January 13, 2019): 1–15. http://dx.doi.org/10.1155/2019/4867327.
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Water is an abundant commodity and has various important functions. It stabilizes the structure of biological macromolecules, controls biochemical activities, and regulates interfacial/intermolecular interactions. Common aspects of interfacial water can be obtained by overviewing fundamental functions and properties at different temporal and spatial scales. It is important to understand the hydrogen bonding and structural properties of water and to evaluate the individual molecular species having different hydration properties. Water molecules form hydrogen bonds with biomolecules and contribute to the adjustment of their properties, such as surface charge, hydrophilicity, and structural flexibility. In this review, the fundamental properties of water molecules and the methods used for the analyses of water dynamics are summarized. In particular, the interrelation between the hydration properties, determined by molecules, and the properties of molecules, determined by their hydration properties, are discussed using the lipid membrane as an example. Accordingly, interesting water functions are introduced that provide beneficial information in the fields of biochemistry, medicine, and food chemistry.
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Barthen, Peter, and Walter Frank. "The `super acid' BF3H2O stabilized by 1,4-dioxane: new preparative aspects and the crystal structure of BF3H2O·C4H8O2." Acta Crystallographica Section E Crystallographic Communications 75, no. 11 (October 31, 2019): 1787–91. http://dx.doi.org/10.1107/s2056989019014312.
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Highly Brønsted-acidic boron trifluoride monohydrate, a widely used `super acid-catalyst', is a colourless fuming liquid that releases BF3 at room temperature. Compared to the liquid components, i.e. boron trifluoride monohydrate and 1,4-dioxane, their 1:1 adduct, BF3H2O·C4H8O2, is a solid with pronounced thermal stability (m.p. 401–403 K). The crystal structure of the long-time-stable easy-to-handle and weighable compound is reported along with new preparative aspects and the results of 1H, 11B, 13C and 19F spectroscopic investigations, particularly documenting its high Brønsted acidity in acetonitrile solution. The remarkable stability of solid BF3H2O·C4H8O2 is attributed to the chain structure established by O—H...O hydrogen bonds of exceptional strength {O2...H1—O1 [O...O = 2.534 (3) Å] and O1—H1...O3i [2.539 (3) Å] in the concatenating unit >O2...H1—O1—H2...O3i<}, taking into account the molecular (non-ionic) character of the structural moieties. Indirectly, this structural feature documents the outstanding acidification of the H2O molecule bound to BF3 and reflects the super acid nature of BF3H2O. In detail, the C 2 2(7) zigzag chain system of hydrogen bonding in the title structure is characterized by the double hydrogen-bond donor and double (κO,κO′) hydrogen-bond acceptor functionality of the aqua ligand and dioxane molecule, respectively, the almost equal strength of both hydrogen bonds, the approximatety linear arrangement of the dioxane O atoms and the two neighbouring water O atoms. Furthermore, the approximately planar arrangement of B, F and O atoms in sheets perpendicular to the c axis of the orthorhombic unit cell is a characteristic structural feature.
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Ueki, Takeshi, and Ryo Yoshida. "Recent aspects of self-oscillating polymeric materials: designing self-oscillating polymers coupled with supramolecular chemistry and ionic liquid science." Phys. Chem. Chem. Phys. 16, no. 22 (2014): 10388–97. http://dx.doi.org/10.1039/c4cp00980k.
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Herein, we summarise the recent developments in self-oscillating polymeric materials based on the concepts of supramolecular chemistry, where aggregates of molecular building blocks with non-covalent bonds evolve the temporal or spatiotemporal structure.
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Enea, Ramona, Ana-Maria Resmeriţă, Laura Petraru, Cristian Grigoraş, Dan Scutaru, Cristofor Simionescu, and Nicolae Hurduc. "Synthesis and photochromic behavior of some azo-polysiloxanes modified with nucleobases or donor-acceptor groups." Open Chemistry 5, no. 4 (December 1, 2007): 981–95. http://dx.doi.org/10.2478/s11532-007-0042-8.
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AbstractThis paper presents the syntheses, characterization and photochromic behavior of some new azo-polysiloxanes modified with uracil, cytosine or nitro-phenolic groups. Taking into consideration the possibility of generating H-bonds or donor/acceptor interactions, this class of materials present a potential applicability in the immobilization of biomolecules and their nano-manipulations. Also, such compounds are capable of producing a fluid phase, with directional flowing capacity. For all these polymers, the molecular modeling simulations have shown disordered structures, which would generate amorphous phases, a very important aspect for molecules’ nano-manipulation. The photochromic behavior in the presence of UV irradiation was also evaluated.
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Demadis, Konstantinos D., Raphael G. Raptis, and Peter Baran. "Chemistry of Organophosphonate Scale Growth Inhibitors: 2. Structural Aspects of 2-Phosphonobutane-1,2,4-Tricarboxylic Acid Monohydrate (PBTC.H2O)." Bioinorganic Chemistry and Applications 3, no. 3-4 (2005): 119–34. http://dx.doi.org/10.1155/bca.2005.119.
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Industrial water systems often suffer from undesirable inorganic deposits, such as calcium carbonate, calcium phosphate(s), magnesium silicate, and others. Synthetic water additives such as phosphonates and phosphonocarboxylates are the most important and widely utilized scale inhibitors in a plethora of industrial applications. The design of efficient and cost-effective inhibitors, as well as the study of their structure and function at the molecular level are important areas of research. This study reports the crystal and molecular structure of PBTC (PBTC = 2-phosphonobutane-1,2,4-tricarboxylic acid), one of the most widely used scale inhibitors in the cooling water treatment industry. Triclinic PBTC monohydrate crystallizes in the P 1 space group with cell dimesions, a =7.671(1) Å, b = 8.680(1) Å, c = 9.886(1) Å, α = 65.518(2) deg, β = 71.683(2) deg, γ = 76.173(2) deg, V = 564.20(11) Å3, and Z = 2. Bond distances in the -PO3moiety are 1.4928(10) Å for the P=O double bond and 1.5294(10) Å and 1.5578(10) Å for the two -P-O(H) groups. P-C and C-O bond lengths fall in the normal range. A network of hydrogen bonds are formed between the water molecule of crystallization, the -P-OH and the -COOH groups.
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STASYUK, I. V., and A. L. IVANKIV. "THERMODYNAMICS OF THE MOLECULAR COMPLEXES WITH CHAINS OF HYDROGEN BONDS." Modern Physics Letters B 06, no. 02 (January 20, 1992): 85–91. http://dx.doi.org/10.1142/s0217984992000119.
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A pseudo-spin reduced basis model for the description of the linear hydrogen-bonds molecular systems with strong correlations between protons on the neighbouring bonds is proposed. The proton states corresponding to the high-energy proton configurations near the heavy ionic groups are excluded from the initial basis. Some aspects of thermodynamics and energy spectrum for the proton subsystem of the molecular complexes are considered in the framework of reduced basis model. It is shown that for the complexes with large but finite number of hydrogen bonds N, the polarizability is proportional to N2, the specific heat is proportional to N−1 and the spectrum includes both zone and localized proton states. At the same time it is shown that correct thermodynamic limit is obtained as N→∞ on the base of pseudo-spin model with initial basis. As a result the limits of application of reduced basis model are determined.
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Rezler, Mateusz, Teresa Żołek, Irena Wolska, and Dorota Maciejewska. "Structural aspects of intermolecular interactions in the solid state of 1,4-dibenzylpiperazines bearing nitrile or amidine groups." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 70, no. 5 (September 18, 2014): 820–27. http://dx.doi.org/10.1107/s2052520614013754.
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The crystal structures of the title 1,4-bis(4-cyanobenzyl)piperazine (1) and 1,4-bis(4-amidinobenzyl)piperazine tetrahydrochloride tetrahydrate (2) are reported. Compound (1) crystallizes in the triclinic space group P\bar 1 and compound (2) in the monoclinic space groupP21/n. In both (1) and (2) the asymmetric unit contains one half of the molecule because the central piperazine rings were located across a symmetry center. The packing of both molecules was dominated by hydrogen bonds. The crystal lattice of (1) was formed by weak C—H...N and C—H...π interactions. The crystal structure of (2) was completely different, with cations as well as chloride anions and water molecules taking part in intermolecular interactions. Single-crystal X-ray diffraction studies combined with density functional theory (DFT) calculations allowed the characterization of the intermolecular interactions in those two systems having different types of very strong electrophilic groups: non-ionic nitrile and ionic amidine. Chemical shift data from13C CP/MAS (Cross Polarization Magic Angle Spinning) NMR spectra were analyzed using the different procedures for the theoretical computation of shielding constants.
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Zappone, Bruno, George W. Greene, Emin Oroudjev, Gregory D. Jay, and Jacob N. Israelachvili. "Molecular Aspects of Boundary Lubrication by Human Lubricin: Effect of Disulfide Bonds and Enzymatic Digestion†." Langmuir 24, no. 4 (February 2008): 1495–508. http://dx.doi.org/10.1021/la702383n.
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Puchoňová, Miroslava, Jozef Švorec, and Dušan Valigura. "Some aspects of dimeric metylsalicylatocopper(II) complexes preparation." Acta Chimica Slovaca 5, no. 2 (November 1, 2012): 200–203. http://dx.doi.org/10.2478/v10188-012-0030-2.
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Abstract A systematic study of the preparation of methylsalicylatocopper(II) complexes with or without N-donor ligand has resulted in three new dimeric complexes formation. The investigation has been targeted to two main aspects: the conditions of dimeric complexes preparation and the properties of obtained products. The common stoichiometric formula for all three complexes is Cu(x-MeSal)2(H2O)(ACN)z (where x-MeSal = 3- or 4-methylsalicylate anion, ACN = acetonitrile and z = 0, 1). Used spectral measurements mainly EPR spectroscopy gave the proof about the existence of dimeric “paddle-wheel” units in all three complexes. Moreover, it was concluded that acetonitrile molecules are more probably bonded to copper(II) atoms in apical positions of dimeric units. The water molecules are in coordination sphere only in the case when acetonitrile is not present. However data show that presence of 4-methylsalicylate anions led to strengthening of Cu-N bonds.
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Fischer, Michael. "First-Principles Study of AlPO4-H3, a Hydrated Aluminophosphate Zeotype Containing Two Different Types of Adsorbed Water Molecules." Molecules 24, no. 5 (March 6, 2019): 922. http://dx.doi.org/10.3390/molecules24050922.
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Porous aluminophosphate zeotypes (AlPOs) are promising materials for heat transformation applications using water as a working fluid. Two “types” of adsorbed water molecules can be distinguished in hydrated AlPOs: Water molecules adsorbed in the direct proximity of framework aluminium atoms form bonds to these Al atoms, with the coordination number of Al increasing from four to five or six. The remaining water molecules that are adsorbed in other parts of the accessible pore space are not strongly bonded to any framework atom, they interact with their environment exclusively through hydrogen bonds. The APC-type small-pore aluminophosphate AlPO4-H3 contains both types of H2O molecules. In the present work, this prototypical hydrated AlPO is studied using dispersion-corrected density functional theory (DFT) calculations. After validating the computations against experimental crystal structure and Raman spectroscopy data, three interrelated aspects are addressed: First, calculations for various partially hydrated models are used to establish that such partially hydrated phases are not thermodynamically stable, as the interaction with the adsorbed water molecules is distinctly weaker than in fully hydrated AlPO4-H3. Second, IR and Raman spectra are computed and compared to those of the dehydrated analogue AlPO4-C, leading to the identification of a few “fingerprint” modes that could be used as indicators for the presence of Al-coordinated water molecules. Finally, DFT-based molecular dynamics calculations are employed to study the dynamics of the adsorbed water molecules. All in all, this in-depth computational study of AlPO4-H3 contributes to the fundamental understanding of hydrated AlPOs, and should therefore provide valuable information for future computational and experimental studies of these systems.
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Aschi, Massimiliano, Giorgia Toto Brocchi, and Gustavo Portalone. "A Combined Experimental and Computational Study of Halogen and Hydrogen Bonding in Molecular Salts of 5-Bromocytosine." Molecules 26, no. 11 (May 23, 2021): 3111. http://dx.doi.org/10.3390/molecules26113111.
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Although natural or artificial modified pyrimidine nucleobases represent important molecules with valuable properties as constituents of DNA and RNA, no systematic analyses of the structural aspects of bromo derivatives of cytosine have appeared so far in the literature. In view of the biochemical and pharmaceutical relevance of these compounds, six different crystals containing proton-transfer derivatives of 5-bromocytosine are prepared and analyzed in the solid-state by single crystal X-ray diffraction. All six compounds are organic salts, with proton transfer occurring to the Nimino atom of the pyridine ring. Experimental results are then complemented with Hirshfeld surface analysis to quantitively evaluate the contribution of different intermolecular interactions in the crystal packing. Furthermore, theoretical calculations, based on different arrangements of molecules extracted from the crystal structure determinations, are carried out to analyze the formation mechanism of halogen bonds (XBs) in these compounds and provide insights into the nature and strength of the observed interactions. The results show that the supramolecular architectures of the six molecular salts involve extensive classical intermolecular hydrogen bonds. However, in all but one proton-transfer adducts, weak to moderate XBs are revealed by C–Br…O short contacts between the bromine atom in the fifth position, which acts as XB donor (electron acceptor). Moreover, the lone pair electrons of the oxygen atom of adjacent pyrimidine nucleobases and/or counterions or water molecules, which acts as XB acceptor (electron donor).
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Zhu, Dan, Shihao Zhang, Pingping Cui, Chang Wang, Jiayu Dai, Ling Zhou, Yaohui Huang, et al. "Solvent Effects on Catechol Crystal Habits and Aspect Ratios: A Combination of Experiments and Molecular Dynamics Simulation Study." Crystals 10, no. 4 (April 18, 2020): 316. http://dx.doi.org/10.3390/cryst10040316.
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This work could help to better understand the solvent effects on crystal habits and aspect ratio changes at the molecular level, which provide some guidance for solvent selection in industrial crystallization processes. With the catechol crystal habits acquired using both experimental and simulation methods in isopropanol, methyl acetate and ethyl acetate, solvent effects on crystal morphology were explored based on the modified attachment energy model. Firstly, morphologically dominant crystal faces were obtained with the predicted crystal habit in vacuum. Then, modified attachment energies were calculated by the molecular dynamics simulation to modify the crystal shapes in a real solvent environment, and the simulation results were in agreement with the experimental ones. Meanwhile, the surface properties such as roughness and the diffusion coefficient were introduced to analyze the solvent adsorption behaviors and the radial distribution function curves were generated to distinguish diverse types of interactions like hydrogen bonds and van der Waals forces. Results show that the catechol crystal habits were affected by the combination of the attachment energy, surface structures and molecular interaction types. Moreover, the changing aspect ratios of catechol crystals are closely related to the existence of hydrogen bonds which contribute to growth inhibition on specific faces.
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Barin, Gokhan, Ross S. Forgan, and J. Fraser Stoddart. "Mechanostereochemistry and the mechanical bond." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2146 (May 9, 2012): 2849–80. http://dx.doi.org/10.1098/rspa.2012.0117.
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The chemistry of mechanically interlocked molecules (MIMs), in which two or more covalently linked components are held together by mechanical bonds , has led to the coining of the term mechanostereochemistry to describe a new field of chemistry that embraces many aspects of MIMs, including their syntheses, properties, topologies where relevant and functions where operative. During the rapid development and emergence of the field, the synthesis of MIMs has witnessed the forsaking of the early and grossly inefficient statistical approaches for template-directed protocols, aided and abetted by molecular recognition processes and the tenets of self-assembly. The resounding success of these synthetic protocols, based on templation, has facilitated the design and construction of artificial molecular switches and machines, resulting more and more in the creation of integrated functional systems. This review highlights (i) the range of template-directed synthetic methods being used currently in the preparation of MIMs; (ii) the syntheses of topologically complex knots and links in the form of stable molecular compounds; and (iii) the incorporation of bistable MIMs into many different device settings associated with surfaces, nanoparticles and solid-state materials in response to the needs of particular applications that are perceived to be fair game for mechanostereochemistry.
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Anquetin, Jérémy, and Christian Püntener. "A new species of the large-headed coastal marine turtle Solnhofia (Testudinata, Thalassochelydia) from the Late Jurassic of NW Switzerland." PeerJ 8 (November 12, 2020): e9931. http://dx.doi.org/10.7717/peerj.9931.
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Background The large-headed turtle Solnhofia parsonsi is known by a handful of specimens from the Late Jurassic of Germany and Switzerland (maybe also France). Solnhofia parsonsi is traditionally regarded as a “eurysternid” Thalassochelydia, a group of small to medium sized, mostly lagoonal or marginal turtles found almost exclusively in the Late Jurassic of Europe. More recently, Solnhofia parsonsi has been proposed to be a close relative of Sandownidae, an enigmatic group of Cretaceous to Paleogene turtles characterized by a derived cranial anatomy and a wider geographical distribution. Sandownids may therefore have evolved from thalassochelydian ancestors such as Solnhofia parsonsi. Methods We herein describe new material of Solnhofia from the Kimmeridgian (Late Jurassic) of Porrentruy, NW Switzerland. The bulk of the material consists of an association of a cranium and over 180 shell bones found together in a block of marly limestone. A second cranium and a mandible from slightly younger, but nearby localities are also described. Results We refer the new material to Solnhofia brachyrhyncha n. sp. The new species shares with Solnhofia parsonsi a relatively large head, an extensive secondary palate formed primarily by the maxillae, a greatly developed processus trochlearis oticum with a contribution from the parietal and quadratojugal, a large jugal-palatine contact in the floor of the fossa orbitalis, and a posteromedial process of the jugal running on the dorsal surface of the maxilla and pterygoid. Some of these characteristics are also present in sandownids, but our morphological study clearly shows that Solnhofia brachyrhyncha is closer to Solnhofia parsonsi than to any sandownids. Discussion Solnhofia brachyrhyncha differs from Solnhofia parsonsi in many aspects, notably: a shortened and broader cranium, a shorter and posteriorly broader upper triturating surface with a slightly sinusoidal lateral margin and without contribution from the palatine, a processus trochlearis oticum more oblique in dorsal or ventral view and less concave in anterior view, choanae that do not extend posteriorly on the pterygoids, a more developed processus pterygoideus externus, a condylus mandibularis situated anterior to the level of the occipital plane, a greater ventral exposure of the parabasisphenoid, a mandible about as wide as long, a relatively short symphysis, a lower triturating surface widened posterolaterally thanks to the presence of large laterally projecting dentary tubercles, a stouter and shorter coronoid process, a splenial positioned more anteriorly along the mandibular ramus, costo-peripheral fontanelles extending more anteriorly and posteriorly along the costal series, and an escutcheon shaped central plastral fontanelle formed mostly by the hypoplastra. In addition to the morphology of the new species, we also briefly discuss about observable ontogenetic variations and possible taphonomic origin of the assemblage.
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Czajlik, András, Jeanett Holzknecht, László Galgóczy, Liliána Tóth, Péter Poór, Attila Ördög, Györgyi Váradi, et al. "Solution Structure, Dynamics, and New Antifungal Aspects of the Cysteine-Rich Miniprotein PAFC." International Journal of Molecular Sciences 22, no. 3 (January 25, 2021): 1183. http://dx.doi.org/10.3390/ijms22031183.
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The genome of Penicillium chrysogenum Q176 contains a gene coding for the 88-amino-acid (aa)-long glycine- and cysteine-rich P. chrysogenum antifungal protein C (PAFC). After maturation, the secreted antifungal miniprotein (MP) comprises 64 aa and shares 80% aa identity with the bubble protein (BP) from Penicillium brevicompactum, which has a published X-ray structure. Our team expressed isotope (15N, 13C)-labeled, recombinant PAFC in high yields, which allowed us to determine the solution structure and molecular dynamics by nuclear magnetic resonance (NMR) experiments. The primary structure of PAFC is dominated by 14 glycines, and therefore, whether the four disulfide bonds can stabilize the fold is challenging. Indeed, unlike the few published solution structures of other antifungal MPs from filamentous ascomycetes, the NMR data indicate that PAFC has shorter secondary structure elements and lacks the typical β-barrel structure, though it has a positively charged cavity and a hydrophobic core around the disulfide bonds. Some parts within the two putative γ-core motifs exhibited enhanced dynamics according to a new disorder index presentation of 15N-NMR relaxation data. Furthermore, we also provided a more detailed insight into the antifungal spectrum of PAFC, with specific emphasis on fungal plant pathogens. Our results suggest that PAFC could be an effective candidate for the development of new antifungal strategies in agriculture.
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Hamed, Gary R. "Molecular Aspects of the Fatigue and Fracture of Rubber." Rubber Chemistry and Technology 67, no. 3 (July 1, 1994): 529–36. http://dx.doi.org/10.5254/1.3538689.
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Abstract This short review highlights molecular mechanisms controlling the fracture of rubber and rubber reinforcement, with emphasis on the importance of mechano-chemistry. The manuscript is an extension and update of a previous short review published in Rubber Chemistry and Technology in 1991. All solids, including vulcanizates, contain inevitable ubiquitous flaws of various shapes and sizes. When a solid is subjected to a global stress, the local stresses at the tips of these flaws are magnified and can be many times larger than the average applied stress. Generally, there will be a single flaw at which the stress is magnified to the greatest degree and where fracture begins. Macroscopic fracture of vulcanized rubber is a process in which network chains are broken and new free surface area is created as a result of mechanical loading. Loading may be continuously increasing up to fracture (monotonic fracture) or it may be applied periodically, typically at much lower levels, until fracture ensues (fatigue fracture). For example, a specimen which breaks at, say, 20 MPa when loaded monotonically in tension may fracture, nonetheless, at only 5 MPa, if this load is repeatedly applied. In many rubber articles, two important types of fatigue fracture are fatigue crack growth and abrasion. With the former a (bulk) crack initiates (perhaps at an included impurity or microvoid) and grows as a result of “far-field” loading, whereas, with abrasion, fracture is caused by the direct action of frictional, sliding forces. The events occurring at the tip of a crack are quite important in controlling its growth. In particular, if a crack tip becomes blunted during deformation, or if there are other processes occurring which reduce the load borne by the molecular chains at the crack tip, then stress concentration will be reduced and fracture inhibited. If an elastomeric network is capable of dissipating input energy into heat through irreversible molecular motions, less elastic nergy will be available to break network bonds apart, and fracture energy is increased. More on the role of energy dissipation in fracture is given later. Both fatigue crack growth and abrasion are the culmination of accumulated damage due to mechano-chemical processes. Consider a rubbery article which contains a distribution of chain lengths between crosslink points, and which is subject to fatigue. When deformed, chains align, and the load is inequitably carried by the network strands. The network strives to distribute the stress among the chains, but it is limited from completely doing so because of the complex topology. At sufficiently low elongation, no chains are broken, but as deformation progresses, one network chain eventually ruptures. The force that the chain was carrying prior to breakage is quickly distributed among neighboring chains. This results in the overloading and rupture of some of these chains. (Electron spin resonance spectroscopy has been used to detect free radicals resulting from homolytic cleavage of network chains.) At this point, there has been molecular chain breakage (network damage), but no macroscopic fracture (creation of new free surface area). Chain breakage is not random, but rather is more prevalent in those “elements” where chains broke in the first place. If deformation were monotonously continued to a high level, there would be a particular element which experienced more chain rupture than any other, and a macroscopic crack would open there (far-field loading) or a portion of the material would be removed (frictional loading). However, in (mild) fatigue the article is unloaded well before sufficient damage has occurred in the first cycle to cause crack growth or abrasive loss. After the first cycle, the article contains elements with varying degrees of damage. In subsequent cycles there is more chain rupture (damage accumulation) and eventually macroscopic fracture ensues. It is interesting to calculate the number of chains which must break at one location in order to create 1 µm2 of fracture surface. Assuming a chain cross-sectional area of 0.5 nm2, this would require the rupture of 2(106) chains. Nonetheless, the number of localized molecular chain ruptures necessary to constitute the onset of macroscopic fracture is unclear.
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Azizollahi, Hamid, and José-Antonio García-López. "Recent Advances on Synthetic Methodology Merging C–H Functionalization and C–C Cleavage." Molecules 25, no. 24 (December 13, 2020): 5900. http://dx.doi.org/10.3390/molecules25245900.
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The functionalization of C–H bonds has become a major thread of research in organic synthesis that can be assessed from different angles, for instance depending on the type of catalyst employed or the overall transformation that is carried out. This review compiles recent progress in synthetic methodology that merges the functionalization of C–H bonds along with the cleavage of C–C bonds, either in intra- or intermolecular fashion. The manuscript is organized in two main sections according to the type of substrate in which the cleavage of the C–C bond takes place, basically attending to the scission of strained or unstrained C–C bonds. Furthermore, the related research works have been grouped on the basis of the mechanistic aspects of the different transformations that are carried out, i.e.,: (a) classic transition metal catalysis where organometallic intermediates are involved; (b) processes occurring via radical intermediates generated through the use of radical initiators or photochemically; and (c) reactions that are catalyzed or mediated by suitable Lewis or Brønsted acid or bases, where molecular rearrangements take place. Thus, throughout the review a wide range of synthetic approaches show that the combination of C–H and C–C cleavage in single synthetic operations can serve as a platform to achieve complex molecular skeletons in a straightforward manner, among them interesting carbo- and heterocyclic scaffolds.
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Mague, Joel T., Erin Larrabee, David Olivier, Francesca Vaccaro, Kevin E. Riley, and Lynn V. Koplitz. "Crystal structures of the hexafluoridophosphate salts of the isomeric 2-, 3- and 4-cyano-1-methylpyridinium cations and determination of solid-state interaction energies." Acta Crystallographica Section E Crystallographic Communications 74, no. 9 (August 24, 2018): 1322–29. http://dx.doi.org/10.1107/s2056989018011003.
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The synthesis and crystal structures of the isomeric molecular salts 2-, 3- and 4-cyano-1-methylpyridinium hexafluoridophosphate, C7H7N2 +·PF6 −, are reported. In 2-cyano-1-methylpyridinium hexafluoridophosphate, C—H...F hydrogen bonds form chains extending along the c-axis direction, which are associated through C—H...F hydrogen bonds and P—F...π(ring) interactions into stepped layers. For 3-cyano-1-methylpyridinium hexafluoridophosphate, corrugated sheets parallel to [001] are generated by C—H...F hydrogen bonds and P—F...π(ring) interactions. The sheets are weakly associated by a weak interaction of the cyano group with the six-membered ring of the cation. In 4-cyano-1-methylpyridinium hexafluoridophosphate, C—H...F hydrogen bonds form a more open three-dimensional network in which stacks of cations and of anions are aligned with the b-axis direction. Dispersion-corrected density functional theory (DFT-D) calculations were carried out in order to elucidate some of the energetic aspects of the solid-state structures. The results indicate that the distribution of charge within a molecular ionic cation can play a large role in determining the strength of a cation–anion interaction within a crystal structure. Crystals of 2-cyano-1-methylpyridinium hexafluoridophosphate are twinned by a 180° rotation about the c* axis. The anion in 3-cyano-1-methylpyridinium hexafluoridophosphate is rotationally disordered by 38.2 (1)° in an 0.848 (3):0.152 (3) ratio.