Homogeneous Matrix Research Articles

Strain Energy and Biomechanical Constituent Models in Blood Vessel Tissues

Objective: To show the analysis of mechanical constitutive models in blood vessel tissues with a continuous media approach based on strain energy, which serve as a reference for new mathematical modeling proposals in them. Theoretical Framework: The mechanics of blood vessels, describes the structural and functional behavior of blood vessels and can characterize various cardiovascular diseases. Harmful changes that alter the mechanical response of the walls of blood vessels produce severe alterations in the health of the circulatory system. Predicting the mechanical behavior of blood vessels based on physiological status using biomechanical models is paramount for diagnosis. Therefore, in the present work, an analysis of the constitutive models is carried out with a continuous media approach based on strain energy. Method: Bibliographic review that identifies, analyzes and synthesizes the existing scientific proposals on blood vessel tissue modeling based on the deformation energy theory. Results and Discussion: A bibliographic study of the biomechanical constitutive models of blood vessel walls, generated over time, is presented. The behavior of the vascular wall is analyzed from the deformation energy approach. The benefits, limitations and potentialities of the models are also exposed: a) Strain energy with a transversely isotropic and homogeneous matrix; b) Strain energy with axis-symmetric fiber constants; c) Strain energy with collagen fibers subject to dispersion; d) Strain energy of four families of fibers without dispersion; and e) Strain energy of two families of fibers with anisotropic elastin and fiber recruitment. Implications of the research: The conclusions and analyzes presented serve as a basis for future research and mathematical modeling of the phenomenon of degradation and deformation of blood vessels, which will facilitate the understanding of the phenomenon and the subsequent strengthening of alternative treatment strategies that combat the clinical conditions derived from the transformations of mechanical properties in the same blood vessels. Originality/Value: This study contributes by giving order to the multiple bibliographic information related to the subject. The relevance of this research is evidenced in the conclusions issued when analyzing models based on the theory of continuous media as a function of strain energy.

Concept mapping to promote clinical reasoning in multimorbidity: a mixed methods study in undergraduate family medicine

BackgroundClinical reasoning significantly impacts physicians’ performance and patient care quality. Research into learning transfer within clinical reasoning education, especially in managing multimorbidity in Family Medicine, is crucial. This study evaluates the impact of concept maps (CMs) on promoting clinical reasoning skills among undergraduate students, compared to traditional teaching methods (TM).MethodsA mixed methods approach was used in a controlled, non-randomized study with fifth-year Family Medicine undergraduates allocated to sessions using either CMs or TM. Quantitative data included a feedback questionnaire and evaluation of an individual task. Qualitative data comprised responses to an open-ended question and analysis of problem representation in the individual task.ResultsAmong 313 eligible students, 112 participated (CM: 60, TM: 52). Both groups reported high satisfaction with their teaching methods. The CM group valued the holistic view and organization for managing multimorbidity cases, showing higher odds of positive scores on individual tasks (differences not statistically significant). Additionally, the CM group had a more homogeneous code matrix for problem representation in two clinical vignettes.ConclusionsWhile no definitive evidence supports the superiority of CMs over traditional methods, promising trends were noted. The CM group showed improved performance in individual tasks and better organization in managing multimorbidity cases. Further investigation is recommended to explore varying levels of CM usage and modifications to pre-class workloads.Clinical trial numberNot applicable.

Pengaruh Tipe Mobil Terhadap Harga dan Kapasitas Mesin di Belarus Dengan Pendekatan Metode Manova

Belarus is a country on the European Continent that continues to develop modern technology, especially in the field of the transportation industry. Supported by people's consumption patterns that tend to be consumptive where the demand for goods can affect the country's economy if not controlled properly, one of which is the use of cars. The high interest of the public in the use of cars is influenced by the design of the body type. Body type plays an important role in determining consumer preferences. The design of the car body type also affects the selling price. Engine capacity is also closely related, where larger vehicles typically have larger tanks. Therefore, it is important to analyze the influence between car body type and price and car engine capacity in Belarus using the multivariate analysis of variance (MANOVA) method. Data analysis starts from describing the characteristics of variables, then conducting MANOVA assumption testing starting from multivariate normality testing with Q-Q plot and T-proportion test, independence correlation test test with barlet test, and homogeneity test with box's m test. Followed by the MANOVA test on the body variable on the price and capacity of the car engine and after that the LSD test. The results of the price characteristics and the capacity of the car engine were obtained by one and two outliers, respectively, and the shape of the boxplot was asymmetrical The most observed type of car was the universal type. The results of the MANOVA assumption test show that the data is normally distributed multivariate, dependent, and has a homogeneous covariance variance matrix. The results of the MANOVA test show that there is at least one type of car that has a significant influence on the price and capacity of the car engine. The LSD test results show the type of car based on the price of the car that there is no difference between the average car type 1, 2, 3, 4.

An information-theoretic Machine Learning for upscaling and downscaling of uncertainty stochastic reservoir

This work brings together theoretical formulation and computational strategies for upscaling random heterogeneous media. In this context, heterogeneous means multiphysics models at different scales and correlated random parameters at different locations in the physical domain, such as Stokes-Brinkman flow and fractures at the microscale and heterogeneous Darcy flows at the macroscale when the target problem is hydrocarbon reservoir simulation, or a matrix with random inclusions on the rich scale and a homogeneous matrix on the poor scale when the target problem is solid mechanics. The approach uses information-theoretic machine learning methods to extract relevant probabilistic information from the rich scale and adaptively control the stochastic distance between the responses of the two scales. A goal-oriented upscaling procedure is defined to ensure equivalence between poor targets and rich scales for specific outcomes and its generalization to a multi-goal-oriented mathematically sound response, where users control distinct accuracies of specific target responses. Preliminary applications for elliptic and transient equations are presented with their respective results comparisons. Applications use a series of realizations of rich-scale parameter distributions, producing a reduced number of equivalent poor-scale realizations as required by the user's desired accuracy. The full formulation requires solving a difficult optimization problem for an extended Lagrangian formulation which is solved with a new Parallel Deterministic Annealing. The mathematical formulation is such that parallelization is done over realizations, so the overall cost of calculating stochastic upscaling is of the same order as deterministic. Furthermore, a regression with Tikhonov regularization in linear Machine Learning was used to interpolate and extrapolate data from Parallel Deterministic Annealing in order to find an optimal rich scale.

From Exhaust to Extraction: Evaluating Car Catalysts Waste for a Resilient Economy

Spent Automotive Catalytic Converters (SACC) are comprised of a support (a honeycomb ceramic structure) coated with a catalytic layer, where Platinum Group Elements (PGE), especially Pt and Pd, facilitate oxidation and reduction reactions to reduce hazardous emissions from car engines. This study provided information about various measurement procedures and principles for characterising SACC, revealing that SACC can release Potentially Toxic Elements (PTE) under environmental conditions. The SACC samples used primarily contain cordierite and moissanite, likely distinguishable upon visual inspection of waste piles. Unlike geological samples, the SACCs samples, considered as a homogeneous matrix, exhibit major elements such as Al, Si, Mg, and Ba, with minor elements including P, Na, Ca, Fe, Ti, Ce, and Zr, posing challenges for geoanalysts and environmental managers. Sequential extraction demonstrated high concentrations of PGE in the residual phase, especially Pt, Pd, and Rh. All other fractions, oxidisable, reducible and exchangeable, showed significant analytical recoveries of PTE such as Zn, Cu, and other trace elements. Watering bulk samples resulted in exceeded reference thresholds, with high Cd, Ni, and Zn, identifying SACC as a potentially hazardous materials. Toxicity tests on three aquatic species (A. fischeri, R. subcapitata, and D. magna) indicated both acute and chronic effects, further highlighting the need for proper waste management. The characterisation approach suggested here can help define the most appropriate SACC treatment demonstrating economic profit and ecological benefits.

Antiplane effective properties of two‐phase micropolar elastic fiber‐reinforced composites with parallelogram‐like unit cells

AbstractIn this contribution, heterogeneous micropolar elastic fiber‐reinforced composites (FRCs) with a periodic structure are analyzed using the two‐scale asymptotic homogenization method (AHM). We focus on predicting the antiplane effective properties of micropolar two‐phase FRCs with parallelogram‐like unit cells. The periodic structure is defined by unidirectional, infinitely long, and concentric cylindrical fibers embedded in a homogeneous matrix. Constituent materials are assumed centro‐symmetric isotropic materials, and perfect interface conditions are considered. The AHM allows us to address the local problems on the periodic cell and determine the corresponding effective properties. This is achieved by employing two‐scale asymptotic expansions for the displacement and microrotation fields, which depend on both macro‐ and micro‐scales. The complex variable theory, combined with the complex‐potential method and doubly periodic Weierstrass elliptic functions, is applied to determine the solution of the antiplane local problems. Simple closed‐form formulas are provided for the antiplane stiffness and torque effective properties of two‐phase micropolar elastic FRCs, which depend on the physical properties and volume fractions of constituents. Finally, numerical examples are reported and discussed. Comparisons with other theoretical models are also presented, and good agreements are obtained.

The Thermomechanical, Functional and Biocompatibility Properties of a Au-Pt-Ge Alloy for PFM Dental Restorations.

A high-noble Au-Pt-Ge porcelain-fused-to-metal (PFM) dental alloy without the known adverse metallic elements and with the addition of germanium (Ge) was produced as a more cost-effective alternative to other precious alloying metals, with investigations for determining the functionality and clinical use of this alloy. The thermomechanical, biocompatibility, durability, workability and economic characteristics of the produced dental alloy were investigated. These properties were investigated with in vitro biocompatibility testing on human gingival fibroblasts (HGFs); static immersion testing for metal ion release; DSC analysis; hardness, tensile testing, density and coefficient of thermal expansion (CTE) measurements; metallographic and SEM/EDX microstructure investigations; and finally with the production of a test PFM dental bridge. The results of the thermomechanical testing showed alloy properties suitable for dental restorations and clinical use, with somewhat lower mechanical properties, making the alloy not suitable for extensive multiunit fixed restorations. The microstructure investigations showed segregations of Ge in the homogeneous alloy matrix, which reduce the alloy's mechanical properties. The produced PFM dental bridge showed excellent workability of the alloy in a dental laboratory setting, as well as a high standard of the final dental restoration. The ion release was negligible, well below any harmful quantities, while the cell viability examination showed significantly higher viability ratings on polished alloy samples as compared to as-cast samples. The results showed that a dental substructure in direct contact with oral tissue and fluids should be highly polished. The performed investigations showed that the produced PFM dental alloy is suitable for clinical use in producing high-quality dental restorations with high biocompatibility for patients prone to metal allergies.

Structural, morphological and Magnetic studies of Soft magnetic Fe-Si-B Metallic Glass ribbons

Abstract A comparative study of two metallic glass ribbons produced by two different industries namely M/s Honeywell corporation, U.S.A., and M/s Vijay electricals. The potential of different experimental techniques like XRD, SEM and EDAX and VSM has been carried out for two soft metallic glass ribbons. XRD studies reveal that for sample A has two broad peaks and sample B shows the absence of any sharp peaks indicating crystalline secondary phases are <5%. Morphological studies show that sample A has homogeneous matrix whereas sample B has crystallites of varied shapes and sizes distributed in the range of 5-40 μm. EDAX for both the samples A and B was done to investigate the compositional elements. VSM measurements reveals sample B to exhibit a relatively larger anisotropy compared to sample A.

The Deposition of Hydroxyapatite Particles Within an Organic Matrix on the Surface of Poly(lactic acid).

Hydroxyapatite (HAP) is a well-established material in biomedical applications, especially for bone tissue regeneration, dental implants, and drug delivery systems. Recent research emphasizes enhancing the biocompatibility and osteoconductivity of orthopedic implants using HAP. This study explores the potential of combining HAP with a lipid matrix to improve the surface properties and biocompatibility of poly(lactic acid) (PLA)-based, 3D-printed, resorbable bone implants. We utilized the Langmuir-Blodgett method to deposit HAP within a dihexadecyl phosphate (DHP) matrix onto PLA substrates. This study demonstrates that DHP and HAP form stable monolayers at the air/water interface with HAP particles distributed within a homogeneous lipid matrix. The presence of HAP and the resulting changes in surface free energy (SFE) are hypothesized to enhance the biocompatibility of PLA implants. Our findings indicate that films composed of DHP + HAP 5:1 are particularly effective in altering PLA surface characteristics, potentially improving osteointegration, and reducing microbial adherence. Overall, this work highlights that surface modification of PLA with HAP and lipid matrices is the first step towards new, promising, and cost-effective strategies for developing advanced biomaterials for bone regeneration.

The effects of fragmentation per se on patch occupancy are stronger and more positive in a landscape with a higher quality and more homogeneous matrix

Habitat fragmentation per se ‐ independent of habitat amount ‐ often increases patch occupancy, possibly because patches are closer together in landscapes with higher fragmentation per se, which should increase dispersal success. Here, we ask whether this effect is influenced by the quality and/or heterogeneity of the landscape matrix, i.e. the non‐habitat portion of the landscape. Specifically, we expect the positive effect of fragmentation per seshould be accentuated when matrix quality is high, reducing dispersal mortality. In contrast, when matrix quality is low, high dispersal mortality should lead to fewer colonisations, and accumulation of extinctions across the smaller patches in a more‐fragmented landscape could lead to negative effects of fragmentation per se. Additionally, matrix heterogeneity could obscure fragmentation effects, as the link between habitat spatial distribution and between‐patch dispersal becomes less predictable. We test these ideas using Glanville fritillary butterfly Melitaea cinxia occupancy data for 4291 habitat patches in the Åland Islands, Finland. Habitat patches for the study species are discrete and well‐defined areas where at least one of the two host species occurs. Adult individuals disperse from habitat patches, spending time in the landscape matrix while searching for new habitat patches. Our predictions were mostly supported. Fragmentation effects were more strongly positive when matrix quality was high; however, we did not see the predicted negative effect of fragmentation per se in landscapes with low matrix quality. As predicted, fragmentation effects on patch occupancy were weaker in landscapes with a more heterogeneous matrix. Our findings may explain why fragmentation effects are often weak. They also suggest that the moderating effects of matrix quality and heterogeneity should be explicitly considered when interpreting effects of habitat fragmentation per se on species distributions.

Insight into the Cationic Charge Distribution in U1-y-zPuyAmzO2±x Mixed Oxides.

Uranium-plutonium mixed oxides, containing few mol % of Am, are currently studied as fuel for Sodium Fast Reactors. The study of the O/M ratio of these fuels is of main interest, as its variation can induce issues for reactor safety. For this purpose, four U1-y-zPuyAmzO2±x samples (0.235 ≤ y ≤ 0.39 and 0.005 ≤ z ≤ 0.02) were studied using electron probe microanalysis (EPMA), X-ray powder diffraction (XRD), and X-ray absorption spectroscopy (XAS) experiments. EPMA analyses revealed a homogeneous matrix phase with few U- and Pu-rich agglomerates. A matrix phase of fluorite structure (face-centered cubic), as well as a small contribution of a UO2 phase of the same structure, was evidenced for all of the samples by XRD. The O/M ratios of the (U,Pu)O2±x matrix were calculated based on the obtained lattice parameters. XANES experiments highlighted the simultaneous presence of U5+ and Pu3+/Am3+ for all of the samples, indicating a charge compensation mechanism even for stoichiometric samples. Based on the EPMA and XRD results, it was evidenced that this coexistence of U4+, U5+, Pu3+, Pu4+, and Am3+ was not originating from the U- and Pu-rich agglomerates. It was found to be rather a peculiarity of the U1-y-zPuyAmzO2±x matrix phase, discussed with the help of thermodynamic calculations performed on the U-Pu-Am-O system.

Mesoscale Modeling of Microcapsule-Based Self-Healing Cementitious Composites under Dynamic Splitting Tension

Microcapsule-based self-healing cementitious composite (MSCC) offers autonomous damage repair, extending the service life of structures. However, most of the existing studies focus on static behavior and healing effectiveness but rarely explore dynamic responses. This study developed the mesoscale modeling approach to investigate MSCC behavior under dynamic split tensile loading. At the mesoscale, MSCC can be treated as a four-phase composite consisting of coarse aggregates, interfacial transition zones, cement mortar, and microcapsules. Alternatively, it can be simplified as a two-phase composite comprising a homogeneous mortar matrix and microcapsules. Four-phase and two-phase mesoscale MSCC models were developed for 2D simulations, while a two-phase 3D model was also developed for comparison. Mesoscale numerical simulations were conducted based on Split-Hopkinson Pressure Bar Brazilian disk-splitting tests, considering various strain rates. Simulation results of different mesoscale models were compared with experimental results. All of the models accurately predicted the tensile strength of MSCC, with the 2D four-phase model providing the best representation of failure modes and crack propagation. Both experimental and numerical data exhibited obvious strain rate effects, indicating that MSCC’s mechanical properties were sensitive to the loading rate. Dynamic increase factors were obtained, quantifying rate sensitivity. The obtained dynamic mechanical properties of MSCC provide insights for designing MSCC components and structures that can better withstand collisions or explosions.

Existence and Uniqueness of Homogeneous Linear Equation Solutions in Supertropical Algebra

This research investigates the existence and uniqueness of solutions to homogeneous linear equations in supertropical algebra. We analyze the structure of supertropical matrices to identify the conditions in which nontrivial solutions exist for the system of equations A⊗𝒙 ⊨ 𝜀, where A is a matrix over a supertropical semiring and x is a vector. By applying determinant-based criteria, we demonstrate how tropical and supertropical values influence the solution space. The research applies theorems that determine the presence of trivial and nontrivial solutions and uses examples to illustrate practical methods for solving homogeneous matrix systems. This highlights the distinct characteristics of supertropical algebra compared to classical linear algebra. Our findings provide a deeper insight into solution behaviors in supertropical systems, paving the way for further research in tropical mathematics.

Numerical investigation into the influence of interfacial transition zone on elastic modulus, creep, shrinkage of concrete

Interfacial transition zone (ITZ) is a weak part around aggregate in concrete, which could threaten the macroscopic properties of concrete such as strength, stiffness, deformation, and durability. However, it is difficult to quantify the ITZ effect on the macroscopic behavior of concrete only by experimental methods due to the tiny thickness of ITZ. This study employed finite element (FE) method to investigate the ITZ effect on the elastic modulus, creep, and shrinkage. A mesoscale three-phase FE model consisting of homogeneous matrix phase, aggregates and ITZ around them was developed for concrete in this study. The influences of the FE model dimension and the meshing size on the calculated results were first discussed. Then the influence of the thickness, viscoelasticity and shrinkage of ITZ on the macroscopic properties of concrete were evaluated based on the FE calculation and grey relation analysis. Finally, the measured elastic modulus, creep and shrinkage of concrete with different contents of clay on coarse aggregates were used to validate the FE model. It is found that the calculated results of the two-dimensional (2D) FE model are in good agreement with those of the three-dimensional (3D) FE model under the linear viscoelastic assumption. The meshing size has a minor effect on the calculated results when it is 0.2–2 times of the ITZ thickness. The influence of ITZ properties on the macroscopic properties of concrete will become more significant as the ITZ thickness increases. Moreover, the elastic modulus of ITZ has a greater impact on the effective properties of concrete than the thickness, creep, and shrinkage of ITZ. The findings in study can contribute to a better understanding of ITZ effect on the macroscopic properties of concrete and provide references to the reasonable consideration of ITZ in numerical studies.

Optical fiber shape reconstruction algorithm based on 3D Euler spiral model

Abstract This paper presents a reconstruction algorithm that uses a 3D Euler spiral model to construct the microsegment of a 3D space curve to improve the reconstruction efficiency. Euler spiral is a curve whose shape information changes linearly with arc length, which improves the current assumption of the reconstruction algorithms that the shape information of the micro-segment is constant, and effectively reduces the number of interpolations required, and thus improves the efficiency of the shape algorithm. To verify the effectiveness of this algorithm, a method for constructing random space curves is proposed. Three random space curves of different lengths are reconstructed and the results are compared with the reconstruction algorithms based on the homogeneous transformation matrix and Bishop frame. The results show that this model can significantly improve the efficiency of the algorithm. Under the random space curves of 1 m, 10 m, and 100 m, the efficiency is enhanced by about 15, 27, and 30 times respectively. Prepare a shape sensor with a length of 1465mm to verify the highest reconstruction accuracy of 3D Euler spiral model, which is consistent with the simulation results. The results provide a solid foundation for further research in the field of shape sensing, and show potential for promoting the development of applications that rely on real-time shape measurements.

Architecture of interconnected cubic NiCo2S4 decorated mesoporous carbon with self-doped nitrogen based-hydrogel for high performance hybrid supercapacitor

Although the transition metal sulfides have shown persuasive proof and stellar traits for energy storage applications, their real applications still possess some obstacles such as prolonged ionic and electronic transport. Hence, NiCo2S4 decorated a pyrolyzed hydrogel (NiCo2S4@PHG) via facile synthesis is considered a promising electrocatalyst for energy storage devices. The prepared electrode materials were characterized utilizing different analysis techniques like XPS, XRD, FT-IR, TGA, SEM, TEM, elemental mapping and EDX that reveal the crucial role of the hydrogel pyrolysis in creating a homogenous nitrogen-doped carbon matrix. The as-fabricated 0.5 NiCo2S4@PHG nanocomposite was electrochemically examined in a sealed workstation cell and showed a clear battery-type supercapacitor behavior attributed to various redox reactions, porosity, and conductivity that was enhanced by self-doped nitrogen. In contrast, composites based on nickel and cobalt sulfides individually with pure hydrogel demonstrated the superiority of binary metal composites. The 0.5 NiCo2S4@PHG electrode exposed a marvelous specific capacity of 317.9 mAh g−1 and capacitance of 2728.5 F g−1 at a current density of 1 A g−1. A hybrid asymmetric supercapacitor was established by 0.5 NiCo2S4@PHG (cathode) and activated carbon (AC, anode), which brought large energy and power densities of 32.8 Wh kg−1 and 750 W kg−1, respectively. The fabricated cell manifests ultra-high retention of 82.6% at a current density of 20 A g−1 after 10,000 cycles. These outstanding accomplishments hold significant potential for practical energy storage and conversion applications.

The ultrastructure of peroxisomes in the kidney of the camel (Camelus dromedarius).

Dromedary camels can survive and reproduce in desert areas. The unique anatomical structure of the kidney enables the camel to prevent water loss. The present study aimed to investigate the ultrastructure of the peroxisomes in the normal kidney of the adult dromedary camel. Tissue samples were taken from the cortex and outer medulla of the kidney of eight camels. The samples were then processed for histological and ultrastructural investigations. The epithelial cells of the proximal tubules displayed peroxisomes with varying sizes and shapes. The peroxisomes were observed in either dispersed or clustered arrangement. Each peroxisome exhibited a homogenous matrix enveloped by a single membrane. Several peroxisomes exhibited one or more dark marginal plates that were always strongly associated with the smooth endoplasmic reticulum. The intensity of the peroxisomal matrix differed significantly, either within the same cell or across different cells. The intensity was light or dark, with a few peroxisomes presenting a similar intensity to that of the mitochondria. Some peroxisomes contained nucleoids within their matrix. The peroxisomes in the first and second sections of proximal convoluted tubules were scattered and primarily located in the region between the microvilli and the underlying mitochondria. The peroxisomes in the third region were abundant and frequently aggregated in clusters throughout the cytoplasm. In the fourth region, the number of peroxisomes was low. The proximal straight tubule had a limited quantity of peroxisomes. In conclusion, peroxisomes in the proximal tubule in kidney of normal dromedary camel were similar in shape and size to other mammals; however, heterogeneity exists as a result of differences in species-specific peroxisomal proteins. Peroxisomes are suggested to be a major source of metabolic energy and act as hydrogen peroxide (H2O2) scavengers, resulting in the release of water and oxygen.

Stress Wave Propagation and Decay Based on Micro-Scale Modelling in the Topology of Polymer Composite with Circular Particles.

This article deals with stress wave decay performance, analysing the stress wave propagation generated by an impulsive unit load in a 2D representative unit cell (RUC) of a polymer composite with circular particles representing spherical particles, elliptical particles, and short fibres. The micro-scale numerical simulation uses explicit finite element analysis (FEA). The micro-response to an impulsive unit load creates a stress wave amplitude interacting with the material structure and tends to weaken and absorb energy. The stress wave damping is determined by the decaying amplitudes of Mises stress at the front of the stress wave. The stress wave damping is evaluated for different ratios of tensile modules and material densities of matrix and reinforcing material and other factors, such as percentage and particle size, applied to nine topologies of RUCs, and even the presence of an interfacial region is analysed. Moreover, the article visualises the phases of stress wave decay in various particle distributions, i.e., various topologies. Analysing the different topologies of the same particle volume (area) percentage, the study proved that the composite topology and resulting wave-particle and wave-wave interactions are other sources of material damping. The presence of even a small percentage, 3.5 area%, of reinforcing circular particles in the matrix brings a significant increase in stress wave damping up to about 40-43% (depending on the topology) compared to a homogeneous matrix with stress wave damping of 12.5% under the same conditions. Moreover, the topology with the same volume (area) percentage can increase particle stress wave damping by 15.3%.

A homogeneous binary matrix assisted laser desorption/ionization time-of-flight mass spectrometry assay for determination of artificial sweeteners in beverages

Artificial sweeteners have been widely used as additives in various beverages. Due to the safety risks associated with artificial sweeteners, it is essential to develop a simple, rapid, and high-throughput method for the analysis of artificial sweeteners. Here, we report a homogeneous binary matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) assay for the simultaneous analysis of sweeteners including aspartame (ASP), neotame (NEO), and advantame (ADV) with a simple dilution step. The combination of nanodiamonds with 2,5-dihydroxybenzoic acid effectively improved the signal response of sweeteners, decreased the background noise, and improved the “spot-to-spot” repeatability. After the optimization, the method exhibits low limits of detection (ASP: 20 nΜ; NEO: 10 nΜ; ADV: 5 nΜ), good linearity (r > 0.995), satisfactory accuracy (96.2–103.0%), and lower RSDs (1.5–5.8%). Finally, the target sweeteners in 17 soft beverages were successfully determined with this method, showing the potential for the routine analysis of artificial sweeteners.

Effect of the matrix volume fraction on the oxidation resistance of porous CVI-processed C/C composites

The correlation between the amount of chemical vapor infiltrated matrix inside porous C/C composites and their resistance to oxidation was investigated. Three C/C samples with homogeneous matrix fractions from 17% to 59% were oxidized in a thermogravimetric apparatus where a diffusion-control regime was reached. The results showed that the materials effective kinetics are proportional to their initial geometric density. With a tripled matrix content, the recession rate dropped by 50% and the depth affected by oxidation fell by 34%. A high matrix fraction was proved to favor the smallest pore sizes and to increase the tortuosity of the diffusion paths.