Matrix Fraction Research Articles

Effect of low fluence radiation on nanocomposite thin films of Cu nanoparticles embedded in fullerene C60

Metal-fullerene nanocomposite thin films with low concentration of Cu metal embedded in fullerene matrix have been synthesized using thermal co-deposition method. An ion irradiation with 120 MeV Ag ions beam was performed to assess the radiation effects for Cu (3%)-C60 nanocomposites at different fluences 1 × 1012, 6 × 1012, 1 × 1013 and 3 × 1013 ions/cm2. Optical properties and surface morphology of nanocomposite thin films were studied using UV-visible spectroscopy and atomic force microscopy, respectively. Absorption spectra demonstrated that absorption intensity of nanocomposite thin film was increased and modes of fullerene were diminished with fluence. The thickness of the film and atomic metal fraction in matrix were estimated by Rutherford backscattering spectroscopy and found to be ∼45 nm and 3%, respectively. Transmission electron microscopy was performed for structural and particle size evaluation of Cu nanoparticles (NPs) in matrix at higher fluence. Structural evolution of copper-fullerene C60 nanocomposite thin films with increasing fluence of 120 MeV Ag ion beam was studied by Raman Spectroscopy, which confirmed the amorphization of matrix (fullerene C60) at higher fluence.

Dynamic Contrast-enhanced MR Imaging Parameters in Bone Metastases from Non-Small Cell Lung Cancer: Comparison between Lesions with and Lesions without Epidermal Growth Factor Receptor Mutation in Primary Lung Cancer.

Purpose To compare dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging parameters between metastatic bone lesions with and without the epidermal growth factor receptor (EGFR) mutation in consecutive patients with primary non-small cell lung cancer (NSCLC). Materials and Methods This study was approved by the institutional review board. Forty-seven patients with NSCLC and a confirmed EGFR mutation status (27 patients were positive and 26 were negative for EGFR mutation), who underwent DCE MR imaging for bone metastases between November 2012 and March 2016, were included in this study. Two radiologists independently analyzed the volume transfer constant (Ktrans), reflux rate (kep), and volume fraction of the extravascular extracellular matrix (ve) using image processing software. Intergroup comparisons of the mean measured parameters were performed with the Mann-Whitney U test. Interobserver agreement was calculated with the intraclass correlation coefficient. Results There was a high level of agreement between the two reviewers for all three parameters (intraclass correlation coefficient = 0.95 for Ktrans, 0.97 for kep, and 0.91 for ve). Ktrans was significantly higher in the EGFR mutation-positive group (P = .039 for reviewer 1, P = .032 for reviewer 2). kep was also higher in the EGFR mutation-positive group but showed statistical significance only in the evaluation performed by one reviewer (P = .048 for reviewer 2, P = .058 for reviewer 1). No significant difference was observed in ve (P = .873 for reviewer 1, P = .889 for reviewer 2). Conclusion The differences in the DCE MR imaging parameters between metastatic bone lesions with and without EGFR mutations in primary NSCLC may be attributed to differences in the vascular structure related to angiogenesis stimulated by the activation of the EGFR signaling pathway. © RSNA, 2017 Online supplemental material is available for this article.

Argonaute2 Cooperates with LaminB to Repress Transcription at Lamin‐associated Domains in Drosophila melanogaster

Argonaute proteins are commonly known as core components of RNA silencing pathways. However, Argonaute proteins have also been shown to possess nuclear functions, such as regulation of transcription, splicing and chromatin architecture. Previous work showed that Drosophila AGO2 functions directly on euchromatin to promote enhancer‐promoter interaction at the homeotic Abd‐B locus independently of the RNA interference (RNAi) pathway. ChIP‐seq analysis revealed that AGO2 binds thousands of sites in the genome, raising the possibility that AGO2 could modulate global chromatin architecture. To identify factors that can function with AGO2 to regulate transcription, we performed immunoaffinity purification of AGO2 from nuclear extracts followed by mass spec analysis. Interestingly, we found that LaminB is enriched among the top AGO2‐associated proteins. Reciprocal co‐immunoprecitation validated the specificity of this interaction, and biochemical fractionation assays confirmed that both proteins reside in chromatin and nuclear matrix fractions. To directly assess the global role of both proteins in transcription, we performed nascent RNA‐Seq upon depletion of either AGO2 or LaminB in Kc167 cells. We found that both proteins co‐repressed a highly significant number of genes, particularly those located at the borders of Lamin‐associated domains (LADs). In order to assess the physiological role of AGO2 in transcriptional regulation, we performed mRNA‐Seq in null versus RNA slicing catalytic activity mutant female larvae. Strikingly, we observed de‐repressed transcription of spermatogenesis genes in the absence of AGO2, independent of its catalytic activity. One of the de‐repressed genes is nht, which encodes a key upstream activator of spermatogenesis gene expression. Null mutation of nht suppresses the up‐regulation of spermatogenesis genes observed in AGO2 null mutants, suggesting that AGO2 acts upstream of nht to silence the spermatogenesis gene program. Given that nht is located within a LAD harboring flanking AGO2 chromatin binding sites, we hypothesized that AGO2 and LaminB could modulate chromatin topology to repress nht. Circular chromosome conformation capture assays (4C‐Seq) using the nht promoter as bait showed a decrease in the frequency of interactions within the LAD upon AGO2 or LaminB knockdown. We conclude that both proteins may repress transcription at LAD borders by regulating chromatin architecture.

Focus: Structure and dynamics of the interfacial layer in polymer nanocomposites with attractive interactions.

In recent years it has become clear that the interfacial layer formed around nanoparticles in polymer nanocomposites (PNCs) is critical for controlling their macroscopic properties. The interfacial layer occupies a significant volume fraction of the polymer matrix in PNCs and creates strong intrinsic heterogeneity in their structure and dynamics. Here, we focus on analysis of the structure and dynamics of the interfacial region in model PNCs with well-dispersed, spherical nanoparticles with attractive interactions. First, we discuss several experimental techniques that provide structural and dynamic information on the interfacial region in PNCs. Then, we discuss the role of various microscopic parameters in controlling structure and dynamics of the interfacial layer. The analysis presented emphasizes the importance of the polymer-nanoparticle interactions for the slowing down dynamics in the interfacial region, while the thickness of the interfacial layer appears to be dependent on chain rigidity, and has been shown to increase with cooling upon approaching the glass transition. Aside from chain rigidity and polymer-nanoparticle interactions, the interfacial layer properties are also affected by the molecular weight of the polymer and the size of the nanoparticles. In the final part of this focus article, we emphasize the important challenges in the field of polymer nanocomposites and a potential analogy with the behavior observed in thin films.

Fracture toughness of the bimodal size lamellar O phase microstructures in Ti-22Al-25Nb (at.%) orthorhombic alloy

Abstract Bimodal size lamellar O phase microstructures containing coarse lamellar O phases and fine acicular O phases were obtained in Ti-22Al-25Nb orthorhombic alloy. The fracture toughness of such microstructure was studied. It is found that a higher volume fraction of B2 matrix and finer B2 grains are both favorable to increase the fracture toughness by inhibiting the propagation of the principal cracks. The microstructure with a higher volume fraction of B2 matrix has fewer lamellar O phases and fewer O/O boundaries. In front of the principal crack, O/O boundaries often provide initiation points of microcracks. The microcracks can promote crack growth by merging with the principal crack. Fewer O/O boundaries provide fewer initiation points of microcracks. In addition, more B2 matrix can blunt the crack more effectively. Thus more B2 matrix also helps prevent the principal crack merging with microcracks. As for the effect of the B2 grain size, finer B2 grains offer more B2 grain boundaries, which provide more obstacles to crack propagation. It is observed that the crack trended to cleavage along some crystal planes of B2 grains. B2 grain boundaries can deflect the cleavage crack and significantly increase the tortuosity of the crack path. Consequently, microstructure with a high volume fraction of B2 matrix and fine B2 grains possesses a high KIC value up to 35.9 MPa m . A model that can predict KIC using tensile properties is utilized. The predicted KIC shows a good agreement with the experimentally measured fracture toughness of the bimodal size lamellar O phase microstructures.

Ambient PM2.5 in the residential area near industrial complexes: Spatiotemporal variation, source apportionment, and health impact

This study systemically investigated the ambient PM2.5 (n=108) with comprehensive analyses of the chemical composition, identification of the potential contributors, and estimation of the resultant respiratory physician visits in the residential regions near energy-consuming and high-polluting industries in central Taiwan. The positive matrix fraction (PMF) model with chemical profiles of trace metals, water-soluble ions, and organic/elemental carbons (OC/EC) was applied to quantify the potential sources of PM2.5. The influences of local sources were also explored using the conditional probability function (CPF). Associations between the daily PM2.5 concentration and the risk of respiratory physician visits for the elderly (≥65years of age) were estimated using time-series analysis. A seasonal variation, with higher concentrations of PM2.5, metals (As, Cd, Sb, and Pb), OC/EC and ions (i.e., NO3−, SO42− and NH4+) in the winter than in the spring and summer, was observed. Overall, an increase of 10μgm−3 in the same-day PM2.5 was associated with an ~2% (95% CI: 1.5%–2.5%) increase in respiratory physician visits. Considering the health benefits of an effective reduction, we suggest that the emission from coal combustion (23.5%), iron ore and steel industry (17.1%), and non-ferrous metallurgy (14.4%), accounting for ~70% of the primary PM2.5 in the winter are prioritized to control.

C3G shows regulated nucleocytoplasmic exchange and represses histone modifications associated with euchromatin.

C3G (RapGEF1) is a ubiquitously expressed guanine nucleotide exchange factor that functions in signaling pathways regulating cell proliferation, apoptosis, and actin reorganization. It is essential for differentiation and early embryonic development in mice. Overexpressed C3G shows predominant cytoplasmic localization, but endogenous C3G is a component of nuclear fractions in a variety of cell types. Coexpression of importin-α and inhibition of nuclear export by leptomycin B resulted in predominant nuclear localization of C3G. Functional NLSs, NES, and GSK3-β-dependent phosphorylation regulate its dynamic nuclear localization. C3G translocates to the nucleus in response to myogenic differentiation and sublethal dose of cisplatin. C3G is associated with chromatin and nuclear matrix fractions. Cells with C3G localized in the nucleus showed peripheralization of heterochromatin and reduced histone modifications associated with euchromatin. Short hairpin RNA-mediated depletion of C3G in epithelial cells resulted in reduced expression of CDK inhibitors and the histone demethylase KDM5A. Myoblast clones with CRISPR/Cas9-mediated knockout of C3G failed to show repression of histone marks and did not show up-regulation of myosin heavy chain and myotube formation when grown in differentiation medium. Our results document regulated nucleocytoplasmic exchange of C3G in response to physiological stimuli and provide insights into nuclear functions for C3G.

Diffusion of a Rouse chain in porous media: A mode-coupling-theory study.

We use a kinetic mode-coupling theory (MCT) combining with generalized Langevin equation (GLE) to study the diffusion and conformational dynamics of a bead-spring Rouse chain (RC) dissolved in porous media. The media contains fluid particles and immobile matrix ones wherein the latter leads to the lack of translational invariance. The friction kernel ζ(t) used in the GLE can be obtained directly by adopting a simple density-functional approach in which the density correlators calculated by MCT equations of porous media serve as inputs. Due to cage effects generated by surrounding particles, ζ(t) shows a very long tail memory in the high volume fraction of fluid and matrix. It is found that the long-time center-of-mass diffusion constant D_{CM} of the RC decreases with the increment of volume fraction, influencing more strongly by the matrix particles than by the fluid ones. The auto-correlation function (ACF) of the end-to-end distance fluctuation can also be calculated theoretically based on GLE. Of particular interest is that the power-law region of ACF has a nearly fixed length in logarithmic scale when it shifts to longer time range, with increasing the volume fraction of media particles. Moreover, the effect of lack of translational invariance has been investigated by comparing the results between fluid-matrix and pure fluid cases under identical total volume fraction.

Quantification of different contributions to dissipation in elastomer nanoparticle composites

We present an approach to quantify different contributions to dissipation in elastomer nanoparticle composites based on strain sweeps. A modified Kraus equation is successfully used to approximate the loss modulus depending on strain amplitude G″γ measured at different temperatures. For natural rubber composites containing >10 vol% carbon black or >3 vol% carbon nanotubes two different contributions to dissipation due to (i) breaking and (ii) deformation of glassy rubber bridges in the filler network are identified. Filler fraction and temperature-dependent trends support physical pictures considering that glassy rubber bridges are responsible for the visco-elasticity of the filler network. Constant extra contributions to dissipation are associated with the bulk-like fraction of the elastomer matrix or filler network independent effects. The achieved understanding should be very important for the optimization of elastomer nanoparticle composites for special applications like tire treads.

An Inversion-Free Estimating Equations Approach for Gaussian Process Models

ABSTRACTOne of the scalability bottlenecks for the large-scale usage of Gaussian processes is the computation of the maximum likelihood estimates of the parameters of the covariance matrix. The classical approach requires a Cholesky factorization of the dense covariance matrix for each optimization iteration. In this work, we present an estimating equations approach for the parameters of zero-mean Gaussian processes. The distinguishing feature of this approach is that no linear system needs to be solved with the covariance matrix. Our approach requires solving an optimization problem for which the main computational expense for the calculation of its objective and gradient is the evaluation of traces of products of the covariance matrix with itself and with its derivatives. For many problems, this is an O(nlog n) effort, and it is always no larger than O(n2). We prove that when the covariance matrix has a bounded condition number, our approach has the same convergence rate as does maximum likelihood in that the Godambe information matrix of the resulting estimator is at least as large as a fixed fraction of the Fisher information matrix. We demonstrate the effectiveness of the proposed approach on two synthetic examples, one of which involves more than 1 million data points.

Experimental Study on Mechanical Properties of Polymer Based Hybrid Composite

The current investigational study observes the mechanical characterization of polymer based hybrid fiber composites. Specimens are kevlar/carbon fibre with vinyl ester resin & glass/carbon fibre with vinyl ester resin hybrids were prepared by hand layup technique, the weight fraction of fibre and matrix was maintained at 60% & 40%. The laminated samples are cut to the ASTM standards. The samples are subjected to elongation & bending loads causing tensile & flexural stress in the constructions. The purpose of this work is to experimentally analyse the progressive failure process of hybrid laminated composites subjected to tensile &flexural loads, and perform the hardness of hybrid composites.

МНОГОМАСШТАБНОЕ МОДЕЛИРОВАНИЕ И АНАЛИЗ МЕХАНИЗМА ВОЗНИКНОВЕНИЯ ТЕХНОЛОГИЧЕСКИХ МЕЖСЛОЙНЫХ НАПРЯЖЕНИЙ В ТОЛСТОСТЕННЫХ КОЛЬЦАХ ИЗ СТЕКЛОПЛАСТИКА

Thick-walled GFRP rings are widely used in high-loaded friction units of working elements of road-building machines as sliding bearings. They must endure high radial loads and work in the condition of a limited lubrication by using the lubricant which is located only in the open pores of the bushing. In large structures of sliding bearings (bearing elements of road-building machines) the thickness of a bushing might be dozens of millimeters. The reality is that it is necessary to use bushings with a rather big thickness to reduce the dynamic load for road-building machines. However, if the thickness of a composite ring increases, it often results in the inter-laminar failure which is caused by high technological (inter-layer) and stretching stresses due to the anisotropic thermal expansion and shrinkage of fabric composites. Furthermore, these stresses can also cause a significant distortion of a thick-walled GFRP ring after machining. In this work, it is assumed that the tension winding of the pre-impregnated fabric on a rigid mandrel leads to a heterogeneous compression of the internal layers and a distortion of the original composite woven structure through the thickness. The threads of the inner layers are curved more than the threads of the outer layers. For this reason, the coefficients of thermal expansion (CTE) of the inner layers happen to be larger than the CTE of the outer layers. Irregular distribution of the CTE gives rise to residual tensile stresses in the transverse (radial) direction. This paper presents the results of dilatometric studies of distributing of the CTE in the thickness of the hoop and axial directions. To determine the volume fraction of filaments and matrix into the threads of GFRP, we used the burn-out method. The observation of slices in the optical microscope allowed us to determine the degree of the curvature of fibres and the thickening of inner ring layers for further 3D modelling. The structure of the woven composite ring was modelled by using impregnated unidirectional (UD microplastic) threads and repeated unit cell. Modulus of elasticity, Poisson's ratios and coefficients of thermal expansion at microscale, macroscale and mesoscale were calculated by FEA (ANSYS Workbench). Thermomechanical properties were used to evaluate the residual technological interlayer stresses in the GFRP sliding bearing busing at the macroscale.

Analysis of the forming behaviour of in-situ drawn sandwich sheets

Abstract One way to produce metal fibre-reinforced plastic-metal sandwich parts is to inject the polymer between the sheets during deep drawing. A new process has been designed in which parts with an interlayer of glas fibres including a thermoplastic matrix and two metallic sheets can be produced by combining deep drawing and thermoplastic-resin transfer moulding (T-RTM). With the possibility of forming sandwich sheets with a wide range of states of the interlayers’ viscosity and due to the polymerisation of the monomers between the sheets, the process combines a lot of advantages but also faces challenges due to the viscous fluid interlayer being hindered from squeezing out. This contribution analyses the dependency of the interlayer on the forming behaviour of the sheets in this process. When forming circular cups with aluminium (AA5182) sheets and a viscous interlayer of different heights, the effect of bulging could be observed which affects a free formed shape during forming. The viscous interlayer does not remain at the same position during forming which leads to an inhomogeneous total blank thickness of the part. In experiments and FE simulations a shape with bulged zones could be observed. An analytical approach for the prediction of these bulge heights has been developed so that both bulge dome heights could be predicted analytically. This approach is verified by experiments and numerical simulations. The results serve to set the process window for the in-situ hybridisation method in which the starting point of injection, volume fraction of the thermoplastic matrix in the fibres, mechanical properties of the materials, and geometrical parameters can be adjusted so that this effect is reduced.

On lambda-matrices and their applications in MIMO control systems design

In the present paper, we have introduced a new control design algorithms based on the theory of matrix polynomials. The first procedure is called block decoupling control which is based on the spectral factors of the denominator of the right matrix fraction description (RMFD), the advantages of this control are the non-interacted behaviour, simplicity in control design and low order controller is obtained due to the cancellation property of the proposed algorithm. The second control algorithm is the whole set of latent-structure assignment via the approaches of block root placement. Of course, the procedure has been developed even if the system is not block transformable, a process done with the aid of conversion between state space and matrix fraction description. The last method defined as a MIMO PID controller design via the placement of block roots with the help of Diophantine equation resolution, the latter systematic procedure retains both regulation and tracking objectives with small gains and minimum error.

Joint genome-wide prediction in several populations accounting for randomness of genotypes: A hierarchical Bayes approach. I: Multivariate Gaussian priors for marker effects and derivation of the joint probability mass function of genotypes

It is important to consider heterogeneity of marker effects and allelic frequencies in across population genome-wide prediction studies. Moreover, all regression models used in genome-wide prediction overlook randomness of genotypes. In this study, a family of hierarchical Bayesian models to perform across population genome-wide prediction modeling genotypes as random variables and allowing population-specific effects for each marker was developed. Models shared a common structure and differed in the priors used and the assumption about residual variances (homogeneous or heterogeneous). Randomness of genotypes was accounted for by deriving the joint probability mass function of marker genotypes conditional on allelic frequencies and pedigree information. As a consequence, these models incorporated kinship and genotypic information that not only permitted to account for heterogeneity of allelic frequencies, but also to include individuals with missing genotypes at some or all loci without the need for previous imputation. This was possible because the non-observed fraction of the design matrix was treated as an unknown model parameter. For each model, a simpler version ignoring population structure, but still accounting for randomness of genotypes was proposed. Implementation of these models and computation of some criteria for model comparison were illustrated using two simulated datasets. Theoretical and computational issues along with possible applications, extensions and refinements were discussed. Some features of the models developed in this study make them promising for genome-wide prediction, the use of information contained in the probability distribution of genotypes is perhaps the most appealing. Further studies to assess the performance of the models proposed here and also to compare them with conventional models used in genome-wide prediction are needed.

Techno-economic analysis and environmental impact assessment of lignocellulosic lactic acid production

Lignocellulosic Lactic acid (LA) production is considered for the diversification and value addition to an existing sugar industry by annexing a biorefinery using lignocellulosic residues, sugarcane bagasse and leaves (SCBL). In biorefinery, the hemicellulose (C5 sugars) and cellulose (C6 sugars), resulting from lignocellulosic matrix fractionation, can be converted into building block chemicals and fuels by biotechnological or chemical pathways. To co-produce LA with other fuels and chemicals from SCBL, it is important to determine whether LA production from C5 or C6 sugars should be preferred, based on economic viability and environmental impacts. In this paper we developed six process scenarios for LA production from either the hemicellulose liquid fraction and cellu-lignin solid fractions of SCBL after steam explosion pretreatment, based on 200tonne/day of SCBL feed. The lignocellulose fraction not used for LA production will be used for integrated production of other marketable products in a biorefinery. Scenarios S1, S3, & S5 use the hemicellulose liquid fraction as feed for LA production, while scenarios S2, S4, & S6 use the cellu-lignin solid fraction. Two scenarios, S1 & S2, use Ca(OH)2 as neutralizer in fermentation, resulting in co-production of gypsum as solid waste, scenarios S3 and S4 use an isolated acid-tolerant thermophilic bacteria, Bacillus coagulans isolates for fermentation, thus avoiding the need for neutralization, while Scenarios S5 and S6 use Mg(OH)2 as neutralizer in fermentation, with recycling of Mg(OH)2. LA was separated and purified from the fermentation broth by reactive distillation. The six process scenarios were modeled and simulated by Aspen Plus® with the resulting mass & energy balance and equipment-sizing used as inputs to economic analysis and environmental impact assessment. Standard life cycle assessment (LCA) method is used in SimaPro® for environmental impact quantification. Cellulose based processes have larger LA production rates than the hemicellulose based processes, for the same flow rate of SCBL, which impacts on their total capital investment (TCI), operating cost (OPEX) and revenues for the same process technology. Increases of 7.08%, 58.13%, 12.04% and 60% in TCI, revenue, OPEX and LA production rates, respectively were observed in moving from S1 to S2. Similar increases of 10.88%, 86.52%, 18.52% and 91.07% in TCI, revenue, OPEX and LA production respectively in moving from S3 to S4. An increment of 10.08%, 61.57%, 18.32% and 63.90% in TCI, revenue, OPEX and LA production respectively was also found in moving from S5 to S6. Scenarios S3 and S4 are found to have lower TCI and OPEX but their production rate is low as well making them economically less attractive with internal rate of return (IRR) of 9.13% and 15.23% respectively. While S1 and S2 have IRR of 13.11% and 19.4% respectively and yet higher TCI and OPEX. S5 and S6 have the highest IRR, 14.72% and 21.28% respectively with TCI and OPEX of way below their equivalent scenarios S1 and S2 respectively. From the environmental point of view S1 and S2 are found to be environmentally less friendly with higher environmental burdens in almost all impact categories considered. Gypsum free scenarios, S5 and S6, are found to be the most attractive processes from both economic and environmental points of view, with S6 being superior than S5.

Composites based on polyurethane–urea and ground rubber from car tyres: relation between structure and properties

The basis of this work is an investigation of multicomponent systems containing a reactive polyurethane–urea matrix, recycled rubber filler, and porosity. Rubber crumb with varying particle sizes obtained from used car tyres was used as the filler. As a matrix, water-curable isocyanate pre-polymer was used. Porosity was caused by the inability of the matrix to fully fill space between rubber particles, combined with foaming from matrix curing. We report on dependences of PUU/rubber system mechanical properties on the composition and structural parameters. Mechanical property values were obtained via tensile loading of prepared rectangular slabs. We found that mechanical behaviour exhibits strong correlation with a structural parameter called interspace filling, which expresses how much the matrix fills space between filler particles. Interspace filling is dependent on the degree of porosity and the volume fraction of the PUU matrix in a hypothetical nonporous material. Therefore, this work offers a simple characterization of complex materials, of which the studied porous composite is an example. Our results could contribute to the development of applications for large volumes of recycled rubber in materials used in rapid repair of roads and pavements.

Microstructure, elastic, and inelastic properties of biomorphic carbons carbonized using a Fe-containing catalyst

The microstructure and amplitude dependences of the Young’s modulus E and internal friction (logarithmic decrement δ), and microplastic properties of biocarbon matrices BE-C(Fe) obtained by beech tree carbonization at temperatures Tcarb = 850–1600°C in the presence of an iron-containing catalyst are studied. By X-ray diffraction analysis and transmission electron microscopy, it is shown that the use of Fe-catalyst during carbonization with Tcarb ≥ 1000°C leads to the appearance of a bulk graphite phase in the form of nanoscale bulk graphite inclusions in a quasi-amorphous matrix, whose volume fraction and size increase with Tcarb. The correlation of the obtained dependences E(Тcarb) and δ(Tcarb) with microstructure evolution with increasing Тcarb is revealed. It is found that E is mainly defined by a crystalline phase fraction in the amorphous matrix, i.e., a nanocrystalline phase at Тcarb 1300°C. Maximum values E = 10–12 GPa are achieved for samples with Тcarb ≈ 1150 and 1600°C. It is shown that the microplasticity manifest itself only in biocarbons with Tcarb ≥ 1300°C (upon reaching a significant volume of the graphite phase); in this case, the conditional microyield stress decreases with increasing total volume of introduced mesoporosity (free surface area).

A weaving machine for three-dimensional Kagome reinforcements

Two-dimensional or three-dimensional (3D) textiles have been used as reinforcement in composite materials. Most techniques for weaving 3D textiles have been developed to obtain a compact preform so that the final product, the fiber-reinforced composite, has a high volume fraction of fibers with the least fraction of matrix for high strength. Contrarily, this article describes a novel technique for weaving a loose 3D preform called wire-woven bulk Kagome with polymer wires or threads. Firstly, the principle is explained by using a manual loom. A weaving machine is then designed with detailed mechanisms and its prototype is presented. Finally, the benefit, shortcomings, and future plans are discussed.

Tensile properties of novel carbon/glass hybrid thermoplastic composite rods

Novel carbon/glass hybrid thermoplastic composite rods consisting of unidirectional PAN-based carbon fiber (T700SC), braids of E-class glass fibers, and thermoplastic epoxy matrix have been developed. Three types of hybrid rods with differing carbon/glass ratios (24K1P, 24K2P, and 24K3P) were fabricated. The cross-sectional morphologies of the hybrid rods were observed using a digital microscope. Volume fractions of carbon fiber, glass fiber, matrix, and void of the hybrid rods were estimated using a specific gravity measurement via ethanol immersion and a thermogravimetric analysis.The tensile properties and fracture behavior of the hybrid rods were investigated. For all hybrid rods, the stress applied to the specimen was nearly linearly proportional to the strain until failure, with a tensile modulus of 65 (24K1P), 87 (24K2P), and 91GPa (24K3P) and tensile strengths of 1.42 (24K1P), 1.80 (24K2P), and 1.84GPa (24K3P). The tensile modulus and strength increased with increasing carbon fiber volume fraction. The Weibull statistical distribution of tensile strength for the hybrid rods was examined. The Weibull modulus of the tensile strengths for the hybrid rods were 23.77 (24K1P), 27.29 (24K2P), and 32.50 (24K3P). The Weibull modulus increased with increasing tensile strength and decreasing void volume fraction of the hybrid rods.