Microscopic Structural Features Research Articles

Subtype Identification in Acutely Dissociated Rat Nodose Ganglion Neurons Based on Morphologic Parameters

Nodose ganglia are composed of A-, Ah- and C-type neurons. Despite their important roles in regulating visceral afferent function, including cardiovascular, pulmonary, and gastrointestinal homeostasis, information about subtype-specific expression, molecular identity, and function of individual ion transporting proteins is scarce. Although experiments utilizing the sliced ganglion preparation have provided valuable insights into the electrophysiological properties of nodose ganglion neuron subtypes, detailed characterization of their electrical phenotypes will require measurements in isolated cells. One major unresolved problem, however, is the difficulty to unambiguously identify the subtype of isolated nodose ganglion neurons without current-clamp recording, because the magnitude of conduction velocity in the corresponding afferent fiber, a reliable marker to discriminate subtypes in situ, can no longer be determined. Here, we present data supporting the notion that application of an algorithm regarding to microscopic structural characteristics, such as neuron shape evaluated by the ratio between shortest and longest axis, neuron surface characteristics, like membrane roughness, and axon attachment, enables specific and sensitive subtype identification of acutely dissociated rat nodose ganglion neurons, by which the accuracy of identification is further validated by electrophysiological markers and overall positive predictive rates is 89.26% (90.04%, 76.47%, and 98.21% for A-, Ah, and C-type, respectively). This approach should aid in gaining insight into the molecular correlates underlying phenotypic heterogeneity of nodose ganglia. Additionally, several critical points that help for neuron identification and afferent conduction calibration are also discussed.

Micro-structure and mechanical properties of the turtle carapace as a biological composite shield

Turtle shell is a multi-scale bio-composite in which the components are arranged in various spatial patterns, leading to an unusually strong and durable structure. The keratin-coated dorsal shell, termed the carapace, exhibits a flat bone, sandwich-like structure made up of two exterior cortices enclosing a cancellous interior. This unique structure was developed by nature to protect the reptile from predator attacks by sustaining impact loads and dissipating energy. In the present study we attempt to correlate the micro-scale architecture with the mechanical properties of the carapace sub-regions of the red-eared slider turtle. The microscopic structural features were examined by scanning electron microscopy and micro-computed tomography. Nanoindentation tests were performed under dry and wet conditions on orthogonal anatomical planes to evaluate the elastic modulus and hardness of the various carapace sub-regions. The mineral content was also measured in the different regions of the carapace. Consequently, we discuss the influence of hydration on the carapace sub-regions and the contribution of each sub-region to the overall mechanical resistance of the assemblage.

Nipple adenoma arising from axillary accessory breast: a case report

Nipple adenoma is a relatively rare benign breast neoplasm, and cases of the disease arising from the axillary accessory breast have very seldom been reported in the English literature. We report a case of nipple adenoma arising from axillary accessory breast including clinical and pathological findings. An 82-year-old woman presented with the complaint of a small painful mass in the right axilla. Physical examination confirmed a well-defined eczematous crusted mass that was 8 mm in size. The diagnosis of nipple adenoma was made from an excisional specimen on the basis of characteristic histological findings. Microscopic structural features included a compact proliferation of small tubules lined by epithelial and myoepithelial cells, and the merging of glandular epithelial cells of the adenoma into squamous epithelial cells in the superficial epidermal layer. Because clinically nipple adenoma may resemble Paget’s disease and pathologically can be misinterpreted as tubular carcinoma, the correct identification of nipple adenoma is an important factor in the differential diagnosis for axillary tumor neoplasms.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1186821489769063

Improvement of electrochemical properties of MgO-coated LiNi0.4Co0.2Mn0.4O2 cathode materials for lithium ion batteries

The surface of LiNi0.4Co0.2Mn0.4O2 cathode is coated using MgO coating materials. The electrochemical properties of the coated materials are investigated as a function of the pH value of the coating solution and the composition of coating materials. Their microscopic structural features have been investigated using scanning electron microscopy and X-ray diffraction. The electrochemical properties of the samples were monitored using coin-cell by galvanostatic charge–discharge cycling test, EDS test, EIS test, and cyclic voltammetry. The coating solution with pH = 10.5 is found to be favorable for the formation of stable coating layers, which enhances the electrochemical properties. In contrast, 2 % MgO-coated LiNi0.4Co0.2Mn0.4O2 shows better cycle performance and rate capability than the bare sample. Such enhancements are attributed to the presence of a stable MgO layer which acts as the interfacial stabilizer on the surface of LiNi0.4Co0.2Mn0.4O2.

Microscopic and mesoscopic structural features of an activated carbon sample, prepared from sorghum via activation by phosphoric acid

An acidic chemical activation procedure has been used for preparing activated carbon with a surface area exceeding 1000m2/g from sorghum. In order to reveal structural features, synchrotron X-ray diffraction measurements have been performed. The structure of the material has been characterized by the total scattering structure factor and the radial distribution function describing short-range arrangement of atoms at distances of the order of a few atomic diameters as well as correlations at a longer scale, of the order of nanometers. The atomic arrangement has been found to be consistent with that of amorphous graphite-like carbon. As far as the mesoscopic structure is concerned, the presence of a characteristic distance is suggested on the basis of the clear nanometer scale oscillations of the radial distribution function, which distance may be assigned as the mesopore size in the material. It is suggested that the approach devized here may later be applied routinely for other activated carbon samples, too, for characterizing atomic and nanoscale order simultaneously.

Insights into Tris‐(2‐Hydroxylethyl)methylammonium Methylsulfate Aqueous Solutions

We report herein a combined experimental-computational study on tris-(2-hydroxylethyl)methylammonium methylsulfate in water solutions, as a representative ionic liquid of the aqueous-solution behavior of hydroxylammonium-based ionic liquids. Relevant thermophysical properties were measured as a function of mixture composition and temperature. Classical molecular dynamics simulations were performed to infer microscopic structural features. The reported results for ionic liquid in water-rich solutions show that it behaves as isolated non-interacting ions solvated by water molecules, through well-defined solvation shells, exerting a disrupting effect on the water hydrogen bonding network. Nevertheless, as ionic liquid concentration increase, interionic association increases, even for diluted water solutions, evolving from the typical behavior of strong electrolytes in solution toward large interacting structures. For ionic-liquid-rich mixtures, water exerts a minor disrupting effect on the fluid's structuring because it occupies regions around each ion (developing water-ion hydrogen bonds) but without significantly weakening anion-cation interactions.

Synthesis and structure refinement studies of LiNiVO4 electrode material for lithium rechargeable batteries

The lithium nickel vanadate (LiNiVO4) cathode material has been synthesized by using sol-gel method. The thermal behavior of the material has been examined by thermogravimetric and differential thermal analysis (TG/DTA). The structure of LiNiVO4 compound has been studied by the Rietveld refined x-ray diffraction (XRD) technique. The Brunauer–Emmett–Teller (BET) surface area of 0.79 m2 g−1 was estimated with N2 absorption characteristics. The synthesized powder morphology was observed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) studies of synthesized LiNiVO4 powder indicate that the oxidation states of nickel and vanadate are +2 and +5, respectively. The electrochemical properties were monitored using 2032 coin cells by cyclic voltammetry and EIS, which showed that the microscopic structural features were deeply related with the electrochemical performance.

Relation of organic and inorganic substances in formation of urolyths

Macro- and microscopic structural features of human urolyths have been studied to reveal the relation between organic and inorganic components and the role of the latter in the process of urolyth formation and growth. The combined study of the shape, color, surface, mineral and organic composition, and internal structure and zoning of 788 urolyths has been performed. Crystallomorphological, polarization-optical, X-ray-diffraction, electron-microscopic, chemical, neutron-activation, and computer technologies of study of the urolyth structure have been used. It has been found that macroscopic characteristics of uroluths (color, shape, surface, and size) did not reflect the chemical composition of urolyths. In the structure of abundance of urolyths in Tomskand the Tomsk Region, oxalates (58%) and urolyths of complex mineral composition (29%) prevail. It has been found that an urolyth is an organomineral aggregate having the internal structure formed by a rhythm of alternation of organic and inorganic layers and the character of arrangement of individual mineral crystals, and the internal structure is independent of the chemical composition of the urolyth and uniform in urolyths of different chemical composition. The most part of urolyths has a mixed (44%) or druzy (35%) type of crystal arrangement and the combined (45%) or grainy (31%) rhythm of alternation of organic and inorganic components.

Modeling and Evaluation of Deformation Behavior of Silica Filled Rubber

The rubbers containing various kinds of fillers exhibit fabulous mechanical characteristic and therefore, they are widely used in various production. Owing to the wide range of controllability in mechanical characteristics by adding the coupling agent, silica-filled rubber draws attention for extensive usage. Here, to clarify the mechanism of the marked increase in deformation resistance in silica-filled rubber in detail, we will construct the finite element homogenization models of silica-filled rubber. These models can reflect various experimental observations that include changes in microscopic structural characteristics such as distribution morphology of silica particles, the thickness of the interfacial phase between silica and rubber, and the networklike gel structures developed from the interfacial phase. The obtained results clarified the essential physical enhancement mechanisms of deformation resistance and hysteresis loss, i.e., the Mullins effect, for rubber filled with silica. The volume fraction of the silica coupling agent essentially affects the deformation behavior of silica-filled rubber suggesting the high controllability of the material characteristics of silica-filled rubber compared with carbon-black- filled rubber. Although, the present model underestimates the hysteresis loss as compared with the experimental results, it has a capability to evaluate the effect of adding coupling agents on the fundamental deformation behavior of silica filled rubber.

Physical and Electrochemical Properties of Layered Li[Ni<sub>1/3</sub>Co<sub>1/3</sub>Mn<sub>1/3</sub>]O<sub>2</sub> Cathode Materials

Li[Ni1/3Co1/3Mn1/3]O2 was synthesized by modified combustion method and effect of calcination temperature on characteristics was investigated. The cycle of Li[Ni1/3Co1/3Mn1/3]O2 was determined by electrochemical measurements, the microscopic structural features were investigated using Fourier transform infrared spectroscope(FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD). The results show that the compound has layered structure with hexagonal lattice. With the increase of calcination temperature, the size of primary particle rises. The Li[Ni1/3Co1/3Mn1/3]O2 calcined at 900 oC shows excellent electrochemical performances with large reversible specific capacity of 152 mAhg-1 in the voltage range of 2.75-4.20 V.

Fractal diffusion of VOCs in dry porous building materials

For the purpose of clarifying the influence of microscopic structural characteristics on the diffusive transport of volatile organic compounds (VOCs) in building materials, many researchers have proposed different models to predict the diffusion process based on the micro-structure analysis. In this study a fractal model was developed and analyzed to investigate the mass transfer characteristics of VOCs’ diffusive transport in dry porous building materials. The classical Fick’s diffusion law was extended to a fractal diffusion model. Using the method of separation of variables, the theoretical solution to a fractal diffusion model of VOCs in a porous structure was obtained. Combined with microscopic pore structure characteristics, the surface fractal dimensions of medium density fiberboards (MDFs) used for building decoration were evaluated by using the experimental results of mercury intrusion porosimetry (MIP). The diffusion process of VOCs in dry porous building materials was simulated by using different surface fractal dimensions and fracton spectral dimensions. Simulated results showed that the surface fractal dimensions and fracton spectral dimensions exhibit different effects on the migration process of VOCs in dry porous building materials. Both the surface fractal dimensions and fracton spectral dimensions reflect the influence of fractal structures on diffusive transport of VOCs. Combining the surface fractal dimensions with fracton spectral dimensions provides a novel interpretation for the diffusion process of VOCs in dry porous building materials.

Effects of different carbonate precipitators on LiNi 1/3Co 1/3Mn 1/3O 2 morphology and electrochemical performance

Compounds LiNi 1/3Co 1/3Mn 1/3O 2 are prepared by adopting different carbonate, i.e., NaHCO 3, NH 4HCO 3 and Na 2CO 3 under the same conditions, which results in the impressive differences in the morphology properties and electrochemical behaviors of LiNi 1/3Co 1/3Mn 1/3O 2. The microscopic structural features of LiNi 1/3Co 1/3Mn 1/3O 2 are investigated using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The electrochemical properties of LiNi 1/3Co 1/3Mn 1/3O 2 are carried out by charge–discharge cycling tests and the electrochemical reactions during charge–discharge process are also investigated by the cyclic voltammetry (CV). Experimental results show that the microscopic structural features, the morphology properties and electrochemical performances are deeply related to the precipitators. In addition, the cyclic voltammetry indicates that the oxidation of nickel occurs by two steps Ni 2+ → Ni 3+ → Ni 4+.

Microscopic structure features changes of rice straw treated by boiled acid solution

This study focuses on the determination of structure change of surface area, morphology, crystallinity and pyrolysis characteristics of cellulosic feedstock treated by hot acid solution. The microscopic structure change of acid-treated samples was examined by using BET, SEM/EDX, XRD and pyrolysis–GC–MS under reasonable condition. Results showed that both surface area and pore volume of treated sample were conspicuous increased partial due to dissolution of silica and organic polar-components. Morphological change of plant cell wall surface was viewed as damage such as exfoliation, cave and fracture appeared on epidermis, vascular bundles. The crystallinity index of residual cellulose microcrystalline was widely enhanced because amorphous hemicellulose was removed off while crystalline was changeless. Under hot acid solution reaction, amorphous hemicellulose was hydrolyzed and leaving larger perfect cellulose thus increasing of crystalline size. Those available cellulose was obvious exposed after acid treatment and gave intensive characteristic peak on pyrogram analyzed by pyrolysis–GC–MS.

Synthesis of LiNi 1/3Co 1/3Mn 1/3O 2 as a cathode material for lithium battery by the rheological phase method

LiNi 1/3Co 1/3Mn 1/3O 2 is prepared by a rheological phase method. Homogeneous precursor derived from this method is calcined at 800 °C for 20 h in air, which results in the impressive differences in the morphology properties and electrochemical behaviors of LiNi 1/3Co 1/3Mn 1/3O 2 in contrast to that obtained by a solid-state method. The microscopic structural features of LiNi 1/3Co 1/3Mn 1/3O 2 are investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD). The electrochemical properties of LiNi 1/3Co 1/3Mn 1/3O 2 are carried out by charge–discharge cycling test. All experiments show that the microscopic structural features and the morphology properties are deeply related with the electrochemical performances. The obtained results suggest that the rheological phase method may become an effective route to prepare LiNi 1/3Co 1/3Mn 1/3O 2 cathode materials for lithium battery.

Mechanical properties and gradient variations of polymers under ultraviolet radiation

AbstractThe photodegradable properties and characteristics of poly(methyl methacrylate) (PMMA) polymers were studied experimentally. Some important mechanical parameters under ultraviolet radiation were measured, such as the elastic modulus, Poisson's ratio, fracture strength, and stress–strain relation. Microscopic structural characteristics of photodegradable PMMA were analyzed with scanning electron microscopy. Also, a functionally graded material of PMMA was fabricated with a photodegradable method and characterized. These results were found to have an important role in evaluating the photodegradable properties of PMMA materials and in developing their engineering applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Examination of the laser-induced variations in the chemical etch rate of a photosensitive glass ceramic

Previous studies in our laboratory have reported that the chemical etch rate of a commercial photosensitive glass ceramic (FoturanTM, Schott Corp., Germany) in dilute hydrofluoric acid is strongly dependent on the incident laser irradiance during patterning at λ=266 nm and λ=355 nm. To help elucidate the underlying chemical and physical processes associated with the laser-induced variations in the chemical etch rate, several complimentary techniques were employed at various stages of the UV laser exposure and thermal treatment. X-ray diffraction (XRD) was used to identify the crystalline phases that are formed in Foturan following laser irradiation and annealing, and monitor the crystalline content as a function of laser irradiance at λ=266 nm and λ=355 nm. The XRD results indicate the nucleation of lithium metasilicate (Li2SiO3) crystals as the exclusive phase following laser irradiation and thermal treatment at temperatures not exceeding 605 °C. The XRD studies also show that the Li2SiO3 density increases with increasing laser irradiance and saturates at high laser irradiance. For our thermal treatment protocol, the average Li2SiO3 crystal diameters are 117.0±10.0 nm and 91.2±5.8 nm for λ=266 nm and λ=355 nm, respectively. Transmission electron microscopy (TEM) was utilized to examine the microscopic structural features of the lithium metasilicate crystals. The TEM results reveal that the growth of lithium metasilicate crystals proceeds dendritically, and produces Li2SiO3 crystals that are ∼700–1000 nm in length for saturation exposures. Optical transmission spectroscopy (OTS) was used to study the growth of metallic silver clusters that act as nucleation sites for the Li2SiO3 crystalline phase. The OTS results show that the (Ag0)x cluster concentration has a dependence on incident laser irradiance that is similar to the etch rate ratios and Li2SiO3 concentration. A comparison between the XRD and optical transmission results and our prior etch rate results show that the etch rate contrast and absolute etch rates are dictated by the Li2SiO3 concentration, which is in turn governed by the (Ag0)x cluster concentration. These results characterize the relationship between the laser exposure and chemical etch rate for Foturan, and permit a more detailed understanding of the photophysical processes that occur in the general class of photostructurable glass ceramic materials. Consequently, these results may also influence the laser processing of other photoactive materials.

Exploring How Different Features of Animations of Sodium Chloride Dissolution Affect Students’ Explanations

Animations of molecular structure and dynamics are often used to help students understand the abstract ideas of chemistry. This qualitative study investigated how the features of two different styles of molecular-level animation affected students’ explanations of how sodium chloride dissolves in water. In small group sessions 18 college-level general chemistry students dissolved table salt in water, after which they individually viewed two animations of salt dissolution. Before and after viewing each animation the participants provided pictorial, written, and oral explanations of the process at the macroscopic and molecular levels. The students then discussed the animations as a group. An analysis of the data showed that students incorporated some of the microscopic structural and functional features from the animations into their explanations. However, oral explanations revealed that in many cases, participants who drew or wrote correct explanations did not comprehend their meanings. Students’ drawings may have reflected only what they had seen, rather than a cohesive understanding. Students’ explanations given after viewing the animations improved, but some prior misconceptions were retained and in some cases, new misconceptions appeared. Students reported that they found the animations useful in learning; however, they sometimes missed essential features when they watched the animation alone.

Investigation on the microscopic features of layered oxide Li[Ni 1 / 3 Co 1 / 3 Mn 1 / 3 ]O 2 and their influences on the cathode properties

Three kinds of samples of Li[Ni 1 / 3 Co 1 / 3 Mn 1 / 3 ]O 2 were prepared respectively from direct solid-state reaction method, combustion method and co-precipitation route and their microscopic structural features have been investigated using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), magnetic susceptibility measurement and X-ray photoelectron spectroscopy (XPS). The microscopic features such as uniform distribution of transition metal ions at 3b-site and the site-exchange ratio between lithium and nickel were found to be significantly dependent on the synthetic routes. The electrochemical properties of three samples were monitored using 2016 coin-cell by galvanostatic charge–discharge cycling test and cyclic voltammetry, which showed that the microscopic structural features are deeply related with the electrochemical performance. The obtained results also suggested that the combustion method may become a much simple alternative synthetic route to the complicate co-precipitation method.

Mechanical manipulation of molecular lattice parameters in smectic elastomers

Smectic liquid crystalline elastomers (SLCE) represent unique materials that combine a 1-D molecular lattice arrangement and orientational order with rubber-elasticity mediated by a polymer network. Such materials may exhibit large thermo-mechanical, opto-mechanical and electro-mechanical effects, due to the coupling of macroscopic sample geometry and microscopic structural features. It is shown that the molecular layer dimensions in the smectic phases can be influenced reversibly by macroscopic strain of the material. We present a microscopic model on the basis of experimental results obtained by mechanical dilatation measurements, optical interferometry, X-ray scattering, (13)C NMR, FTIR and polarizing microscopy data. The model gives an explanation of the controversial results obtained in different types of smectic elastomers.

Comparison of structural features of the fault zone developed at different protoliths: crystalline rocks and mudrocks

We investigated the mesoscopic and microscopic structural features of the Keumwang fault zone, Korea, to determine the effect of different protoliths (crystalline granitic gneiss and mudrock) on fault zone structure including discrete shear surfaces, shear bands, foliation, porphyroclasts and calcite veins. Overall, in crystalline rock, the shear deformation tends to be localized to a fault core or several fault gouge-dominated layers within the fault zone. The cataclastic flow appears to become stronger toward the fault core. Most of the shear deformation appears to be partitioned between slip on discrete shear surfaces and shear bands, and cataclastic flow, including syntectonic alteration in the fine-grained matrix of fault rocks. In contrast, within mudrocks, shear deformation tends to be relatively uniformly distributed within the entire fault zone. Shearing generates continuous S-foliations throughout the whole fault zone. Most of the shearing is accommodated by slip along these foliations and on discrete shear surfaces distributed within the entire fault zone.