Intra-substance meniscal changes and their clinical significance: a meta-analysis

The degeneration of radial tie fibres of the central meniscal layer, and thinning of its lamellar layer results in increased intensity signals on magnetic resonance imaging, making it difficult to differentiate from true meniscal tear. This study aimed to assess the rate of encountered MRI grades 1 and 2 intrasubstance meniscal changes, and to set guidelines to report these changes based on predicted clinical outcome. A systematic review approach was employed using search engines, libraries, and databases (Google Scholar, ERIC, PubMed, and Medline) to search for scholarly sources on meniscal lesions and their significance in MRI published between 1 January 2000 and 30 June 2019. It retrieved 2750 abstracts, out of which 2738 were excluded and 13 studies meeting inclusion criteria were meta-analysed. It found an association between intrasubstances meniscal changes and outcomes. It resulted that intrasubstance meniscal changes were preservable through the protective functioning of the meniscus. Other than weight gain, no other significant risk factor of developing true meniscal tears later in life was found. It is important to examine intrasubstance meniscal change when patients suffer from mechanical meniscal symptoms especially in old age.

Structure and Properties of Graphene Oxide Aerogels by Freeze-Drying Process

The structure and properties of graphene oxide aerogels (GOA), prepared by a modified Hummer’s method followed by a freezing-drying process in addition to a pre-oxidized procedure, were studied through FTIR, Raman, SEM and XDR techniques. FTIR results indicated the existence of -C-O, -C-OH and -C=O function groups on the GOA surface. Therefore, the D band intensity of GOA sample exhibited remarkable increasing in the Raman spectra compared with of graphite; it may be due to change the order-structure of graphite to disorder-structure of GOA. The diffractive peak for the graphite at 2θ of 26.5° vanishes instead the one around 10.0° occurred in the XRD pattern for the GOA supported that the structure and d-spacing changed seriously from graphite to GOA. The SEM images revealed that the micro-structure of graphene layer of GOA was wrinkler and softer than that of graphite, however, the former involved fewer lamellar layer appearance with wrinkles on the edges of the graphene. All the characterized evaluation confirmed that the graphite powder has been transformed into a GOA structure through the modified Hummers’ method.

Micromechanics of elastic lamellae: unravelling the role of structural inhomogeneity in multi-scale arterial mechanics

Microstructural deformation of elastic lamellae plays important roles in maintaining arterial tissue homeostasis and regulating vascular smooth muscle cell fate. Our study unravels the underlying microstructural origin that enables elastic lamellar layers to evenly distribute the stresses through the arterial wall caused by intraluminal distending pressure, a fundamental requirement for tissue and cellular function. A new experimental approach was developed to quantify the spatial organization and unfolding of elastic lamellar layers under pressurization in mouse carotid arteries by coupling physiological extension–inflation and multiphoton imaging. Tissue-level circumferential stretch was obtained from analysis of the deformation of a thick-walled cylinder. Our results show that the unfolding and extension of lamellar layers contribute simultaneously to tissue-level deformation. The inner lamellar layers are wavier and unfold more than the outer layers. This waviness gradient compensates the larger tissue circumferential stretch experienced at the inner surface, thus equalizing lamellar layer extension through the arterial wall. Discoveries from this study reveal the importance of structural inhomogeneity in maintaining tissue homeostasis through the arterial wall, and may have profound implications on vascular remodelling in aging and diseases, as well as in tissue engineering of functional blood vessels.

Crystallography and Textural Aspects of Crossed Lamellar Layers in Arcidae (Bivalvia, Mollusca) Shells

Bivalve shell microstructures are important traits that can be used for evolutionary and phylogenetic studies. Here we examine the crossed lamellar layers forming the shells of the arcoids, Arca noae, Glycymeris glycymeris and Glycymeris nummaria in order to better understand the crystallography of this complex biomaterial. Textural aspects and crystallography of the outer crossed lamellar layer of these species have been clarified using high-resolution electron microscopy and X-ray diffraction (XRD) techniques. These shells are made of aragonite crystals in a crossed lamellar arrangement with a high preferred crystal orientation (texture). The distribution of maxima in the pole figures implies that there is not a single crystallographic pattern within the measured area, but a continuous variation between two classes of distinct patterns. In the first of these, there is a set of four crystal orientations (referred to as upper set). These four crystal orientations are distributed in two pairs (which are coplanar), with the crystals of each pair being twinned on {110}. The pairs are tilted with respect to each other by approximately 20-40º around an axis perpendicular to the {110} common twinning plane. In the second pattern (referred to as lower set), the crystal orientations of each pair are rotated around a <–110> direction until the a-axes of the diametrically opposing crystal orientations of two different twinned pairs become parallel. As a result of this rotation, in the lower set the crystal orientations no longer form pairs twinned on {110}.These crystallographic relationships are unknown in inorganic aragonite. Our results are similar to those reported for the neogastropod Conus marmoreus. Thus, the common crossed lamellar crystallography in the arcoid bivalves and in C. marmoreus is a striking example of convergence in the development of crossed lamellar microstructures.

Constructional morphology of the shell/ligament system in opisthogyrate rostrate bivalves

ABSTRACTThe bivalve ligament provides the thrust for shell opening, acting as the resistance in a lever system against which adductor muscle effort is applied. Usually, its outer lamellar layer is subjected to tensile stress, while the inner fibrous layer is compressed, with the pivotal axis located between them. However, opisthogyrate rostrate bivalves display a concave dorsal margin, and both the umbo and the postero-dorsal angle of the shell project dorsally to the ligament, which then fails to act as pivotal axis. Three opisthogyrate rostrate genera of unrelated lineages show somewhat different solutions to this morpho-functional challenge. In Cuspidaria (Anomalodesmata), the ligament is internal, subjected only to compression and ventral to the pivotal axis, a thickened periostracum develops, forcing the dorsal margins of the valves to act as pivotal axis, and the posterior parts of the shell's dorsal margins gape dorsally. In Nuculana (Palaeotaxodonta), the inner layer of the ligament is internal, the outer layer is external but reduced, and some species develop a dorsal ridge parallel to the commissural plane, on a level with the rostrum and acting as pivotal axis. In Pterotrigonia (Palaeoheterodonta) and other rostrate trigoniides, the ligament is external opisthodetic, but is allometrically reduced. Trigoniides may also develop a dorsal ridge.

Morphological, Histological and Ultrastructural Changes in Fruit Epidermis of Apple Malus Domestica cv. Ligol (Rosaceae) at Fruit Set, Maturity and Storage

Fruit quality is closely related to the structure of the fruit peel, especially the epidermis and cuticle which form a barrier between its internal and external environments. This study used light, scanning and transmission elec-tron microscopy to examine changes in the epidermal structures of fruits of the Polish apple cultivar Malus domestica Borkh. cv. Ligol at three maturity stages. The single-layered epidermis was covered with cuticle and crystalline wax platelets. In the fruit set stage the fruit surface exhibited numerous nonglandular trichomes, stomata, microcracks and crystalline wax platelets. The surface of fruits at harvest and after 6-month controlled-atmosphere storage exhibited lenticels and horizontally or vertically oriented wax platelets. During fruit devel-opment there was an increase in epidermal cuticle thickness and a reduction in epidermal cell convexity and number of lenticels. After the storage period fruit weight declined, microcracks deepened and widened, and cuticular waxes accumulated. The cuticle was made up of two layers, lamellar and reticulate. In successive fruit development stages the width of the lamellar layer increased considerably. In the fruit set and harvest maturity stages the epidermal cells contained numerous mitochondria and plastids with starch grains. After the storage period there were fewer amyloplasts and the cell vacuoles contained flocculent residue and dark deposits.

Microstructure and crystallographic texture of Ranella Olearia Shell

Molluscs are soft-bodied animals, that why many of them invented complex strategies for protecting themselves [1]. One of these strategies consists in creating a rigid biomineral called mollusc shell. Mollusc shells are complex biocomposites of mineral and organic material (5% in volume) with high mechanical performances, compared to the geological mineral. Mollusc shells are mainly made of calcite and aragonite crystalline polymorphs of calcium carbonate. This organic part behaves as nanometer growth-control of the inorganic crystals. This has stimulated chemists and materials scientists to design materials with a microstructure similar to that of nacre. To achieve this, understanding the microstructure of the nacre at various scales is certainly the key [2]. In this work we made use of the Combined Analysis [3] to determine the structure and preferred orientations of constituting aragonite crystallites of the Ranella olerea shell (fig. 1a) layers using scanning electron microscopy and X-rays diffraction. SEM analyses (fig. 1b) show the presence of an inner layer composed of Radial Lamellar, an intermediate comarginal crossed lamellar layer and an outer crossed lamellar layer. The refinement of X-ray diffraction diagrams gives the textures of the three layers, their respective aragonite unit-cell distortions, and the macroscopic elastic tensor of their mineral parts. The textures of the three layers were found to be of high level, especially for the inner layer. Both intermediate and outer layers exhibit regular texture patterns for crossed lamellae with a split of the c-axis component around the normal to the shell. An anisotropic unit-cell distortion is quantified for the three layers which is attributed to the combined effects of inter- and intra-crystalline macromolecules. The simulation of the macroscopic elastic tensor shows that the strong orientations present in the successive layers give an optimisation in terms of rigidity and shear resistance.

Preparation and Characterization of Graphene Oxide

Graphene oxide (GO) films with two-dimensional structure were successfully prepared via the modified Hummer method. It is proven that redox method is a promising way to synthesize GO films on a large scale. Comprehensive characterizations of the properties of GO films were conducted. TEM and DFM analyses showed that GO sheets prepared in this study had single and double lamellar layer structure and a thickness of 2~3 nm. X-ray diffraction (XRD) was selected to measure the crystal structure of GO sheet. Fourier-transform infrared spectra analyzer (FT-IR) was used to certify the presence of oxygen-containing functional groups in GO films. The tests of UV-VIS spectrometer and TGA analyzer indicated that GO sheet possessed excellent optical response and outstanding thermal stability. Elemental analyzer (EA) and X-ray photoelectron spectroscope (XPS) analyzed the components synthetic material. Simultaneously, chemical structure of GO sheet was described in this study. Discussion and references for further research on graphene are provided.