scholarly journals The Specific Molecular Composition and Structural Arrangement of Eleutherodactylus Coqui Gular Skin Tissue Provide Its High Mechanical Compliance

2020 ◽  
Vol 21 (16) ◽  
pp. 5593
Author(s):  
Justin Hui ◽  
Shivang Sharma ◽  
Sarah Rajani ◽  
Anirudha Singh
Keyword(s):  
Molecular Mechanisms ◽  
Helical Structure ◽  
Skin Tissue ◽  
Layer By Layer ◽  
Eleutherodactylus Coqui ◽  
Structure Property ◽  
Layer Arrangement ◽  
Rat Bladder ◽  
Transmission Electron ◽  
Out Of Plane

A male Eleutherodactylus Coqui (EC, a frog) expands and contracts its gular skin to a great extent during mating calls, displaying its extraordinarily compliant organ. There are striking similarities between frog gular skin and the human bladder as both organs expand and contract significantly. While the high extensibility of the urinary bladder is attributed to the unique helical ultrastructure of collagen type III, the mechanism behind the gular skin of EC is unknown. We therefore aim to understand the structure–property relationship of gular skin tissues of EC. Our findings demonstrate that the male EC gular tissue can elongate up to 400%, with an ultimate tensile strength (UTS) of 1.7 MPa. Species without vocal sacs, Xenopus Laevis (XL) and Xenopus Muelleri (XM), elongate only up to 80% and 350% with UTS~6.3 MPa and ~4.5 MPa, respectively. Transmission electron microscopy (TEM) and histological staining further show that EC tissues’ collagen fibers exhibit a layer-by-layer arrangement with an uninterrupted, knot-free, and continuous structure. The collagen bundles alternate between a circular and longitudinal shape, suggesting an out-of-plane zig-zag structure, which likely provides the tissue with greater extensibility. In contrast, control species contain a nearly linear collagen structure interrupted by thicker muscle bundles and mucous glands. Meanwhile, in the rat bladder, the collagen is arranged in a helical structure. The bladder-like high extensibility of EC gular skin tissue arises despite it having eight-fold lesser elastin and five times more collagen than the rat bladder. To our knowledge, this is the first study to report the structural and molecular mechanisms behind the high compliance of EC gular skin. We believe that these findings can lead us to develop more compliant biomaterials for applications in regenerative medicine.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

scholarly journals Facilitated Cross-Bridge Interactions with Thin Filaments by Familial Hypertrophic Cardiomyopathy Mutations inα-Tropomyosin

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Fang Wang ◽  
Nicolas M. Brunet ◽  
Justin R. Grubich ◽  
Ewa A. Bienkiewicz ◽  
Thomas M. Asbury ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Molecular Mechanisms ◽  
Helical Structure ◽  
Familial Hypertrophic Cardiomyopathy ◽  
Maximum Speed ◽  
Sliding Speed ◽  
Thin Filaments ◽  
In Vitro Motility ◽  
Cardiac Sarcomeres

Familial hypertrophic cardiomyopathy (FHC) is a disease of cardiac sarcomeres. To identify molecular mechanisms underlying FHC pathology, functional and structural differences in three FHC-related mutations in recombinantα-Tm (V95A, D175N, and E180G) were characterized using both conventional and modified in vitro motility assays and circular dichroism spectroscopy. Mutant Tm's exhibited reducedα-helical structure and increased unordered structure. When thin filaments were fully occupied by regulatory proteins, little or no motion was detected at pCa 9, and maximum speed (pCa 5) was similar for all tropomyosins. Ca2+-responsiveness of filament sliding speed was increased either by increasedpCa50(V95A), reduced cooperativityn(D175N), or both (E180G). When temperature was increased, thin filaments with E180G exhibited dysregulation at temperatures ~10°C lower, and much closer to body temperature, than WT. When HMM density was reduced, thin filaments with D175N required fewer motors to initiate sliding or achieve maximum sliding speed.

scholarly journals Experimental and Computational Study of a Liquid Crystalline Dimesogen Exhibiting Nematic, Twist-Bend Nematic, Intercalated Smectic, and Soft Crystalline Mesophases

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 532
Author(s):  
Emily E. Pocock ◽  
Richard J. Mandle ◽  
John W. Goodby
Keyword(s):  
Liquid Crystalline ◽  
Computational Study ◽  
Structure Property ◽  
Correlation Lengths ◽  
Aspect Ratios ◽  
Smectic Phases ◽  
Out Of Plane ◽  
Lower Temperature ◽  
Soft Crystal ◽  
Optical Textures

Liquid crystalline dimers and dimesogens have attracted significant attention due to their tendency to exhibit twist-bend modulated nematic (NTB) phases. While the features that give rise to NTB phase formation are now somewhat understood, a comparable structure–property relationship governing the formation of layered (smectic) phases from the NTB phase is absent. In this present work, we find that by selecting mesogenic units with differing polarities and aspect ratios and selecting an appropriately bent central spacer we obtain a material that exhibits both NTB and intercalated smectic phases. The higher temperature smectic phase is assigned as SmCA based on its optical textures and X-ray scattering patterns. A detailed study of the lower temperature smectic ‘’X’’ phase by optical microscopy and SAXS/WAXS demonstrates this phase to be smectic, with an in-plane orthorhombic or monoclinic packing and long (>100 nm) out of plane correlation lengths. This phase, which has been observed in a handful of materials to date, is a soft-crystal phase with an anticlinic layer organisation. We suggest that mismatching the polarities, conjugation and aspect ratios of mesogenic units is a useful method for generating smectic forming dimesogens.

Effect of Nano Dispersant Additions to the Electrodes for Aluminum Electrolysis

2021 ◽  
Vol 875 ◽  
pp. 107-115
Author(s):  
Shahid Akhtar ◽  
Sten Yngve Larsen
Keyword(s):  
Aluminum Electrolysis ◽  
Metallurgical Industry ◽  
High Energy ◽  
Structure Property ◽  
Mixing Conditions ◽  
Carbon Structures ◽  
Technological Advances ◽  
Transmission Electron ◽  
Relationship Of ◽  
Global Carbon

Over the next half decade, significant changes expected in global carbon structures, carbon products and applications. Technological advances that improve the structure-property relationship of advanced carbon materials and breakthrough in manufacturing processes resulting in lower cost, leads to availability of carbon nano materials for applications in the metallurgical industry with a reference to electrodes for the metallurgical industry.In the current work we synthesized pitch-based C/C nano composite lab scale electrodes, partially replacing petroleum coke with nanofibers, by using a ball milling dispersion and high energy milling technique. The effect of different processing variables including the amount of binder and dispersants as well as mixing conditions is investigated. Low vacuum -SEM analyses of green pitch and dispersant samples show the pitch coating on dispersants. Field emission gun (FEG)-SEM is used to analyse dispersants, baked pitch/dispersant system as well baked electrodes. Transmission electron microscope (TEM) is applied to investigate in detail the primary structure of the dispersants, as well as the fiber/matrix interface and the alignment of binder with the fibres in graphitized and un-graphitized electrodes.

scholarly journals Actuation Behavior of Multilayer Graphene Nanosheets/Polydimethylsiloxane Composite Films

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1243 ◽  
Author(s):  
Chunmei Zhang ◽  
Tianliang Zhai ◽  
Chao Zhan ◽  
Qiuping Fu ◽  
Chao Ma
Keyword(s):  
Composite Film ◽  
High Performance ◽  
Graphene Nanosheets ◽  
Composite Films ◽  
Multilayer Graphene ◽  
Layer By Layer ◽  
Pdms Film ◽  
Out Of Plane ◽  
Dielectric Actuation ◽  
Electromechanical Actuation

The graphene nanosheets (GNS)/polydimethylsiloxane (PDMS) composite films with out-of-plane dielectric actuation behavior were prepared through a layer-by-layer spin coating process. The GNS-PDMS/PDMS composite films with 1~3 layers of GNS-PDMS films were spin coated on top of the PDMS film. The dielectric, mechanical, and electromechanical actuation properties of the composite films were investigated. The dielectric constant of the GNS-PDMS3/PDMS composite film at 1 kHz is 5.52, which is 1.7 times that of the GNS-PDMS1/PDMS composite film. The actuated displacement of the GNS-PDMS/PDMS composite films is greatly enhanced by increasing the number of GNS-PDMS layers. This study provides a novel alternative approach for fabricating high-performance actuators with out-of-plane actuation behavior.

Superior Quality Rails: Structure-Phase States and Defect Substructure

2014 ◽  
Vol 1013 ◽  
pp. 127-132 ◽  
Author(s):  
Victor Gromov ◽  
Alexei Yuriev ◽  
Yurii F. Ivanov ◽  
Konstantin Morozov ◽  
Sergey Konovalov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase State ◽  
Layer By Layer ◽  
Quantitative Parameters ◽  
Defect Substructure ◽  
Transmission Electron ◽  
Layer Analysis ◽  
Structure Phase

Using transmission electron microscopy methods the layer by layer analysis of the bulk hardened superior quality rails is carried out and the quantitative parameters of structure, phase state and defect substructure gradients are established. It is shown that the interface boundaries globular cementite particles-matrix are the possible places of microcracks initiation.

Buckypaper/DYAD/Buckypaper and Buckypaper/DYAD/ (polyaniline/multiwalled carbon nanotube) composite sensors: Preparation and damping properties characterization

2017 ◽  
Vol 52 (11) ◽  
pp. 1457-1464
Author(s):  
Weiwei Lin ◽  
Yonatan Rotenberg ◽  
Hadi Fekrmandi ◽  
Cesar Levy
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotube ◽  
Damping Ratio ◽  
Multiwalled Carbon Nanotube ◽  
Layer By Layer ◽  
Test Results ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Nanotube Composites ◽  
Matrix Free

Buckypaper/DYAD/Buckypaper and Buckypaper/DYAD/(polyaniline/multiwalled carbon nanotube) composites films were made by frit compression method and layer-by-layer attachment method. Transmission electron microscopy and scanning electron microscopy were used to study the morphology properties of polyaniline/multiwalled carbon nanotube and the results showed that carbon nanotubes were well dispersed in the polymer matrix. Free vibration test results showed that the double-sided attachment of the sensor had higher damping ratio values than single-sided attachment. Also, damping ratios were higher when the composite sensor was placed at the beam's clamped end. Furthermore, the Buckypaper/DYAD/(polyaniline/multiwalled carbon nanotube) combination exhibited higher damping ratios than the other cases tested. Thus, these samples have the potential of being simultaneously strain sensors and dampers.

scholarly journals Ivermectin induces autophagy-mediated cell death through the AKT/mTOR signaling pathway in glioma cells

2019 ◽  
Vol 39 (12) ◽  
Author(s):  
Jingjing Liu ◽  
Hongsheng Liang ◽  
Chen Chen ◽  
Xiaoxing Wang ◽  
Faling Qu ◽  
...  
Keyword(s):  
Cell Death ◽  
Molecular Mechanisms ◽  
Anticancer Agent ◽  
Glioma Cells ◽  
Mtor Signaling ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Transmission Electron ◽  
Diphenyltetrazolium Bromide

Abstract Glioma is one of the most common types of primary brain tumors. Ivermectin (IVM), a broad-spectrum antiparasitic drug, has been identified as a novel anticancer agent due to its inhibitory effects on the proliferation of glioma cells in vitro and in vivo. However, the ability of IVM to induce autophagy and its role in glioma cell death remains unclear. The main objective of the present study was to explore autophagy induced by IVM in glioma U251 and C6 cells, and the deep underlying molecular mechanisms. In addition, we examined the effects of autophagy on apoptosis in glioma cells. In the present study, transmission electron microscopy (TEM), immunofluorescence, Western blot and immunohistochemistry were used to evaluate autophagy activated by IVM. Cell viability was measured by 3-(4,5-dimethylthiazol2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and colony formation assay. The apoptosis rate was detected by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Meanwhile, autophagy inhibition was achieved by using chloroquine (CQ). U251-derived xenografts were established for examination of IVM-induced autophagy on glioma in vivo. Taken together, the results of the present study showed that autophagy induced by IVM has a protective effect on cell apoptosis in vitro and in vivo. Mechanistically, IVM induced autophagy through AKT/mTOR signaling and induced energy impairment. Our findings show that IVM is a promising anticancer agent and may be a potential effective treatment for glioma cancers.

Thermotropic Chiral Nematic Polymers as Optical Materials

1989 ◽  
Vol 175 ◽  
Author(s):  
S.H. Chen ◽  
M.L. Tsai ◽  
S.D. Jacobs
Keyword(s):  
Optical Materials ◽  
Helical Structure ◽  
Structural Features ◽  
Optically Active ◽  
Structure Property ◽  
Chiral Compound ◽  
Structure Property Relationships ◽  
Chiral Nematic ◽  
Chiral Structures ◽  
Nematic Polymers

AbstractChiral nematic copolymers based on optically active cholesterol, dihydrocholesterol, (R)-(+)- and (S)-(−)-1-phenylethylamine, and (+)- and (−)- isopinocampheol were synthesized and characterized for the investigations of thermotropic and optical properties. Although helical sense does not appear to correlate with the sign of [α]D of the precursor chiral compound as suggested by the observations of cholesteryl and dihydrocholesteryl copolymers, the inversion of chirality in the pendant group, (R)-(+)- vs (S)-(−)-1-phenylethylamine, does lead to the opposite handedness in the resultant helical structure. To better understand the structure-property relationships involving helical sense and twisting power, systematic studies of the roles played by both nematogenic and chiral structures as well as other structural features of the comonomers should be conducted.

Attritious Wear of Silicon Carbide

1976 ◽  
Vol 98 (4) ◽  
pp. 1125-1134 ◽  
Author(s):  
R. Komanduri ◽  
M. C. Shaw
Keyword(s):  
Silicon Carbide ◽  
Electron Microscope ◽  
High Temperature ◽  
High Speed ◽  
Layer By Layer ◽  
Wear Area ◽  
Work Material ◽  
Transmission Electron ◽  
Metal Silicides ◽  
Boundary Fracture

Attritious wear of silicon carbide in simulated grinding tests against a cobalt base superalloy at high speed and extremely small feed rate was studied using a scanning electron microscope (SEM) and an auger electron spectroscope (AES). In many cases the wear area of silicon carbide was found to be concave rather than planar in shape. Several microcracks and grain boundary fracture were also observed. No evidence of metal build-up was observed on silicon carbide which was not the case with aluminum oxide. AES study of the rubbed surface on the work material and transmission electron microscope (TEM) investigation of the wear debris suggest that attritious wear of silicon carbide is due to one or more of the following mechanisms: 1 – Preferential removal of surface atoms on the abrasive, layer by layer, by oxidation under high temperature and a favorably directed shear stress; 2 – disassociation of silicon carbide at high temperature and (a) diffusion of silicon into the work material and formation of metal silicides and (b) diffusion of carbon into the work material and formation of unstable metal carbides (in the present case Ni3C and Co3C) which decompose during cooling to metal and carbon atoms; 3 – pinocoidal cleavage fracture of silicon carbide on basal planes c(0001) resulting in the removal of many micron-sized crystallites.

Sign in / Sign up

Export Citation Format

Share Document