Composite Samples Research Articles

Changes of gluten protein composition during sourdough fermentation in rye flour

AbstractBackground and ObjectivesCeliac disease (CD) is an immune‐mediated condition triggered by gluten consumption. Although more studies stated that gluten proteins are partially degrading during sourdough fermentation, it is still unclear whether the CD toxic epitopes are affected. Our aim was to examine the effect of controlled sourdough fermentation on the gluten content and composition with different sourdough starters in rye flour.FindingsDespite significant changes in protein size distribution and a decrease in secalin types confirmed by high‐performance liquid chromatography methods, the enzyme‐linked immunosorbent assay results showed increased gluten content after fermentation. The incomplete degradation of gluten and the potential resistance of celiac toxic epitopes may explain our results. As part of the R5 antibody binding, epitopes are supposed to be unavailable in the native form of secalins; they might be released and become accessible in the smaller protein fragments.ConclusionsIn comparison of the effect of different starter cultures, the results show that the different microbiological composition of the sourdough samples might be the reason for the differences in the protein degradation.Significance and NoveltyResults highlight the importance of a deeper investigation of the effects of gluten protein degradation on CD toxicity and the standardization of the fermentation process.

The tectonic implications of a rare metamorphic event in eastern China during the Earth's “middle age”

The Mesoproterozoic Era has long been considered a relatively stable, silent, and even "boring" period in Earth's history, during which the lithosphere was tectonically inactive. However, an increasing amount of evidence suggests that metamorphism and magmatism were much more widespread and intense than previously thought, implying that this period was dynamic. Here we report metamorphism around ca. 1.4 Ga along the southeastern margin of the North China Craton, eastern China. We conduct TIMA, EMPA, and zircon SHRIMP and LA-ICP-MS U-Pb dating on garnet amphibolites and their country rocks. The detailed mineral composition of a representive garnet amphibolite sample is identified and determined by TIMA. Phase equilibria modelling using pseudosections combined with EMPA data indicates the peak metamorphism stage (M 2 ) of the garnet amphibolites at a P-T condition of 10.6-11.2 kbar/820 ℃. SHRIMP Zircon U-Pb analysis yields an age of 1366 ± 17 Ma for the garnet amphibolites, which is slightly younger than that of its country rock schist (1376 ± 22 Ma). Integrating the metamorphic event with geochemical signatures, magmatic records, and sedimentation patterns in analogous geological settings on other continents, our findings collectively demonstrate a protracted and pervasive orogenic process along the periphery of the Columbia supercontinent.

Characterization of Microstructure of Fe-TiC and Fe-B4C Composites Using Ultrasonic Measurements

In this paper, an iron (Fe) matrix reinforced with boron carbide (B4C) and titanium carbide (TiC) was produced by conventional furnace sintering at the same compositions and temperatures. Experimental data on the change in ultrasonic velocity parameter, densities and porosity of these two different microstructure composites during microstructure development are reported. The microstructural phases were characterized by metallographic studies and hardness measurements. The velocities of ultrasonic longitudinal waves were measured by the pulse- echo method using the transmit/receive probe. In the Fe-TiC composite sample, ultrasound longitudinal wave velocity, hardness and porosity increased linearly depending on the increasing amount of TiC. In the Fe-B4C composite sample, on the other hand, there is a linear increase in general depending on the increasing amount of B4C, and there is a sharp decrease in the amount of 8,33% B4C. The reason for this decrease and other results are explained by taking into account SEM and XRD analyzes.

Risk assessment and quantification of elemental concentrations in river and stream in Nigeria

The rising prevalence of elements in surface water is becoming a major global environmental problem due to their resistance to change and capacity to accumulate in organisms. Humans are causing significant heavy metal contamination in the aquatic environment, which is killing aquatic creatures. The purpose of this study is to determine the elemental composition of surface water in Ogun State. Water samples were collected from a river that flows alongside Liberty Estate in Ewupe, Ado-Odo Ota Local Government Area, and a stream that runs alongside Pacific Estate in Iganmode. The element composition of water samples was determined using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Several components were found to exceed the limitations imposed by the World Health Organisation (WHO) and the Environmental Protection Agency (EPA). In River I, sodium (Na) had the highest apparent concentration, whereas titanium (Ti) had the lowest average concentration. In River II, silicon (Si) had the highest apparent concentration, whereas chromium (Cr) had the lowest average concentration. Titanium (Ti) had the lowest mean concentration value, whereas sodium (Na) appeared to have the highest concentration in stream I. Stream II has the highest concentration of sodium (Na), while Uranium (U) has the lowest average concentration value. Nonetheless, the incremental lifetime cancer risk (ILCR) values for adults and children who drink river and stream water are similar, ranging from 10–9 to 10–8. This implies a high carcinogenic risk (CR) linked with drinking water from both sources. Children who had access to both stream and river water demonstrated higher risk levels than adults. Routine studies of the state's streams and rivers should be conducted to avoid the subtle impact that may emanate from the water bodies.

Detection of virulent and ESBL-resistant Salmonella species from cattle and associated farm environment

The aim of this study was to explore the virulence characteristics and antibiotic resistance in Salmonella species isolated from cattle farms. During the study, 10 cattle farms were selected and from each farm, 35 samples consisting of faeces, milk, udder swabs, hand swabs, floor swabs, animal drinking water, pit water, composite fodder sample, and dairy utensil swabs were collected. Accordingly, 350 samples were collected from 10 farms and processed for the detection of Salmonella spp. Presumptive Salmonella isolates were confirmed by PCR and characterized for virulence and antibiotic resistance genes. From 350 samples, 19 (5.40%) Salmonellae were recovered, and out of 19 Salmonellae, 12 were ESBL producers. Similarly, out of 19 isolates, spvC was the predominant gene detected (42.10%), followed by stn (31.5%), and spvR (26.31%), whereas, invA, and iroB genes were detected in all 19 Salmonella isolates. Most of the Salmonella isolates were multi-drug resistant strains exhibiting resistance to nalidixic acid (94.73%), tetracycline (36.84%), and ceftazidime (42.10%). Out of 12 ESBL-positive Salmonellae, 9 (75%) isolates harboured ESBL genes, viz. blaSHV and blaTEM (25% each) and blaCTX-M and blaOXA (16.66% each). Six Salmonella isolates showed the presence of tetA gene. The current study indicated healthy cattle and the associated farm environments could be a source of virulent and drug-resistant Salmonellae. The current study also advocates phenotypic and genotypic antibiotic resistance monitoring at farm animal premises and agricultural ecosystems.

Optimization through combined compromise solution and weight determination through SHANNON-ENTROPY for multi criteria decision making in tribological testing of ultrahigh molecular weight polyethylene nano-composite in SBF environment and compression testing with it’s invitro analysis

Aluminium oxide and graphene reinforced with ultrahigh molecular weight polyethylene (UHMWPE) composites offer significant potential for prosthetic and implant applications due to their unique combination of properties. In this article, a series of aluminium oxide and graphene reinforced with ultrahigh molecular weight polyethylene (UHMWPE) composites were successfully fabricated through compression moulding. The average hardness of all the composites was observed to be higher than the UHMWPE (6.1 Hv). Composite U-15A-5 G was found to be the hardest with hardness of 10.5 Hv owing to strong bond between Al2O3 and UHMWPE. The compression strength of the U-15A-5 G material was about 81.936 MPa, which is 40.9% better than the pure UHMWPE. The compression modulus was about 330 MPa which is 22.2% higher than neat UHMWPE. Composite samples were tribo tested under simulated body fluid (SBF) lubricating environment. Using combined entropy-COCOSO method it was found that 50 mm/s speed, 200N load and 5% graphene are the optimum tribological parameters. with Cof of 0.04 and wear rate of 4.8745*10−4 mm3/Nm. Microstructure analysis indicated that long-range structured lamellar structures and microfibers were created between the crystals with the assistance of graphene layers. Apatite layer was also found on the sample. The apatite layer included phosphate and carbonate ions, which is good for in vitro bioactivity on polymeric films. This composite is a good candidate for prosthetics and implant components.

Longitudinal wastewater-based surveillance of SARS-CoV-2 during 2023 in Ethiopia

IntroductionAlthough wastewater-based epidemiology (WBE) successfully functioned as a tool for monitoring the coronavirus disease 2019 (COVID-19) pandemic globally, relatively little is known about its utility in low-income countries. This study aimed to quantify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater, estimate the number of infected individuals in the catchment areas, and correlate the results with the clinically reported COVID-19 cases in Addis Ababa, Ethiopia.MethodsA total of 323 influent and 33 effluent wastewater samples were collected from three Wastewater Treatment Plants (WWTPs) using a 24-h composite Moore swab sampling method from February to November 2023. The virus was captured using Ceres Nanotrap® Enhancement Reagent 2 and Nanotrap® Microbiome A Particles, and then nucleic acids were extracted using the Qiagen QIAamp Viral RNA Mini Kit. The ThermoFisher TaqPath™ COVID-19 kit was applied to perform real-time reverse transcriptase polymerase chain reaction (qRT-PCR) to quantify the SARS-CoV-2 RNA. Wastewater viral concentrations were normalized using flow rate and number of people served. In the sampling period, spearman correlation was used to compare the SARS-CoV-2 target gene concentration to the reported COVID-19 cases. The numbers of infected individuals under each treatment plant were calculated considering the target genes’ concentration, the flow rate of treatment plants, a gram of feces per person-day, and RNA copies per gram of feces.ResultsSARS-CoV-2 was detected in 94% of untreated wastewater samples. All effluent wastewater samples (n = 22) from the upflow anaerobic sludge blanket (UASB) reactor and membrane bioreactor (MBR) technology were SARS-COV-2 RNA negative. In contrast, two out of 11 effluents from Waste Stabilization Pond were found positive. Positive correlations were observed between the weekly average SARS-CoV-2 concentration and the cumulative weekly reported COVID-19 cases in Addis Ababa. The estimated number of infected people in the Kality Treatment catchment area was 330 times the number of COVID-19 cases reported during the study period in Addis Ababa.DiscussionThis study revealed that SARS-CoV-2 was circulating in the community and confirmed previous reports of more asymptomatic COVID-19 cases in Ethiopia. Additionally, this study provides further evidence of the importance of wastewater-based surveillance in general to monitor infectious diseases in low-income settings.ConclusionWastewater-based surveillance of SARS-CoV-2 can be a useful method for tracking the increment of COVID-19 cases before it spreads widely throughout the community.

Evaluation of tribological parameters for boron carbide and graphite infused aluminium hybrid composite fabricated by stir casting technique

The present work focuses on suggesting Gr as a valuable self-lubricating reinforcement for hybrid composite samples and offering a minimum wear rate for sliding pairs with fewer mechanical surface defects at the same time. A series of samples were fabricated using the route by stir casting method considering B4C and Gr as the two reinforcements. The morphology of the sample has been studied using the X-ray diffraction graphs, Energy dispersive X-ray analysis and Scanning electron imaging stating the homogeneity of reinforcement in various composite cast. The theoretical and experimental density of the series of samples has been studied and compared stating the low porosity of the samples fabricated. A maximum wear rate (Wr) of 0.351 × 10−4 mm3/m. was found for pure aluminium sample against EN31 steel disc with 0.053 as friction coefficient (µ). Wr was somehow seen to reduce up to 0.286 × 10−4 mm3/m for Al-B4C composite with µ of 0.48. For hybrid samples, the wear rate was further seen to improve to 0.187 × 10−4 mm3/m for Al-B4C and Gr 2.0% weight with µ of 0.38. Least Wr was found for composite having Gr 3.5% weight, of 0.149 × 10−4 mm3/m. with µ of 0.36. SEM images of the worn surface give evident results for delamination and crack formation on the pin face for the pure-Al sample. Taguchi-ANOVA analysis has been carried out showing the valid contribution of pin type, load and sliding speed on Wr and friction coefficient as the P-value lies below 0.05 for input parameters considering the 95% confidence level of the model developed. An F-value of 44.57 with R2 of 0.895 is developed for Wr model and an F-value of 54.2 with R2 of 0.934 for the µ model.

Bones or Stones: How Can We Apply Geophysical Techniques in Bone Research?

Some studies have used physical techniques for the assessment of bone structure and composition. However, very few studies applied multiple techniques, such as those described below, at the same time. The aim of our study was to determine the chemical and mineralogical/organic composition of bovine tibial bone samples using geophysical/geochemical reference techniques. X-ray diffraction (XRD), thermogravimetry (TG), Fourier-transform infrared spectrometry with attenuated total reflectance accessory (FTIR-ATR), inductively coupled mass spectrometry (ICP-MS) and inductively coupled optical emission spectrometry (ICP-OES) were applied to measure the organic and inorganic composition of 14 bovine bone samples. In addition, peripheral quantitative CT (QCT) was used to assess BMD in these bones. We were able to define the total composition of the studied bone samples. ICP-OES and ICP-MS techniques were used to determine the major and trace element composition. The X-ray analysis could detect inorganic crystalline compounds of bones, such as bioapatite, and its degree of ordering, indicating whether the bones belong to a younger or older individual. The total volatile content of the samples was calculated using TG and resulted in about 35 weight% (wt%). This, together with the 65 wt% total resulting from the chemical analysis (i.e., inorganic components), yielded a total approaching 100 wt%. As a large portion of the volatile content (H2O, CO2, etc.) was liberated from the organic components and, subordinately, from bioapatite, it could be concluded that the volatile-to-solid ratio of the examined bone samples was ~35:65. The FTIR-ATR analysis revealed that the organic portion consists of collagens containing amide groups, as their typical bands (OH, CH, CO, NC) were clearly identified in the infrared spectra. Numerous parameters of bone composition correlated with BMD as determined by QCT. In conclusion, we performed a complex evaluation of bovine bones to test multiple geophysical/geochemical techniques in bone research in association with QCT bone densitometry. From a medical point of view, the composition of the studied bones could be reliably examined by these methods.

Enhanced Mechanical Properties of Ni3Al Composites Reinforced with Single-Walled and Multi-Walled Carbon Nanotubes: An Atomistic Modeling Study

In this study, the mechanical properties of a Ni3Al matrix composite reinforced with single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) were investigated using atomistic modeling. The analysis focused on the behavior of the composite under uniaxial tensile strain across a range of temperatures (100–900[Formula: see text]K). The results demonstrated that the incorporation of any type of carbon nanotubes (CNTs) significantly enhanced Young’s modulus, yield strength, and tensile strength of the Ni3Al matrix. Notably, the reinforcement with MWCNTs resulted in superior mechanical properties compared to SWCNTs. Additionally, an increase in temperature led to a reduction in Young’s modulus for all composite samples. Among the tested configurations, the composite reinforced with MWCNTs exhibited the highest tensile modulus and yield strength, outperforming both the SWCNT-reinforced composite and the unreinforced Ni3Al crystal. These findings underscore the potential of MWCNTs as effective reinforcements in improving the mechanical performance of Ni3Al-based composites, especially at elevated temperatures.

Minoritized language accreditation and equating. Some particularities

ABSTRACT Among the specificities associated with the accreditation of linguistic competence in minoritised languages, one of the most distinctive is the characterisation of the target population. In terms of diversity, test-takers come from the same geographical region, and most of them live in contact with the test language; in terms of quantity, there are fewer candidates than those assessed in L2 language around the world. These particularities have some important implications in any score-equating programme, and so on validity. In this paper, which focuses on Basque, we explore the conditions to define an equating design. We start by analysing the hypothesis of group equivalence among the editions of the HABE C1 test, and then compare some equating procedures. The research is carried out in two steps. The first (N = 14,981) analyses the sample compositions among test editions with relation to gender, age, place of birth, L1 and language of instruction; the second compares some equating procedures applied to the reading and listening test (N = 4765). The results support the hypothesis of group equivalence, and the equating procedures show total concordance around the cut scores. Some implications of the results are provided.

Enhanced carbon monoxide poisoning resistance of Pd/BEA by integrating with CeO2 for low temperature NO adsorption: The role of CeO2 on oxidizing carbon monoxide to CO32−

Passive NOx adsorption (PNA) represents a promising technology for controlling NOx emissions during cold starts. However, Pd/zeolite catalysts, the latest generation of PNA materials, suffer from serious deactivation under CO concentrations, owing to the CO induced aggregation of highly dispersed Pd sites to PdO particles. In this work, we found that the resistance to CO poisoning of Pd/BEA can be enhanced by integrating with CeO2 through physical mixing. The resulting CeO2 + Pd/BEA composite catalyst demonstrated a notably higher NOx storage capacity (with a NOx/Pd ratio of 1.3) compared to Pd/BEA (0.8). This improvement can be attributed to the interaction between CeO2 and the BEA support, which promoted the formation of nitrates on CeO2 during NO adsorption at 80 °C. More importantly, CeO2 effectively shielded Pd2+ ions from reduction by CO, with 88 % of Pd2+ ions remaining after CO exposure, significantly outperforming Pd/BEA, which retained only 66 %. Spectra characterization and DFT results indicate that the defects in CeO2 strongly trapped CO (−0.973 eV), and the oxidation of trapped CO to CO32− by adsorbed oxygen (Oads) was exothermic (−1.35 eV), which reduced the exposure of Pd2+ ions to CO and inhibited the reduction and agglomeration of Pd2+ ions. While the composite sample still exhibited a slight reduction in NOx storage capacity after CO poisoning, with the NOx/Pd ratio decreasing from 1.3 to 0.9. The DFT simulation results indicate that the Ce-Oads bonds in CeO2 are weakened during the decomposition of the CO32− intermediate. This weakening could potentially facilitate the release of Oads, thereby reducing the Oads content as evidenced by spectral evidence. The decrease of Oads diminished nitrate formation on the CeO2 component in composite sample, resulting in the decline of NOx storage capacity after CO poisoning.

Enhancing the quality of haylage from tropical grasses with xylanase enzyme

ABSTRACT The objective was to evaluate the effect of adding xylanase on the aerobic stability, chemical composition, fermentative, and microbiological parameters of tropical grasses preserved as haylage. A completely randomised experimental design with a 4 × 2 factorial scheme was used, involving four cultivars of haylage grasses (Andropogon gayanus cv. Planaltina, Panicum maximum cv. Mombasa, Panicum maximum cv. Massai, and Brachiaria brizantha cv. Marandu) with and without xylanase enzyme. There was no interaction between xylanase and cultivar in pH values at haylage opening. Aerobic stability remained intact during 120 h of air exposure. Cultivar significantly affected lactic and propionic acid content, with greater fermentation in Mombasa grass and higher butyric acid in Massai grass. Differences (P < 0.001) in DM content were noted, with Andropogon, Massai and Marandu grasses showing greatest values. Andropogon grass, with and without xylanase, had the highest (P < 0.05) crude protein content. Marandu grass haylage had the lowest neutral detergent fibre (P < 0.05) and acid detergent fibre (P < 0.001) content. Andropogon grass haylage with xylanase had lower (P < 0.001) yeast amounts. Therefore, the xylanase enzyme dose (1.8 g kg−1 DM) did not significantly alter the chemical composition, fermentative parameters, or aerobic stability of the haylage samples across different tropical grass cultivars.

Development and analysis of Fe-doped ZnO nanoparticle-infused sisal fiber reinforced hybrid polymer composites for high-performance sound absorption and thermal insulation applications

In the current study, sisal fiber-reinforced hybrid composites have been developed by integrating a bidirectional mat with a blend of epoxy using Fe-doped ZnO (IDZO) nanoparticles at concentrations of 0.2, 0.4, 0.6, and 0.8 wt%. Hand-lay-up approach was used to create the composites. The composites were characterized through a comprehensive analysis of their density, water absorption, elasticity, thermogravimetric analysis, mechanical resistance, thermal conductivity, microhardness, and propagation of sound properties, including sound absorption coefficients and sound transmission class ratings. As filler loading increased, the bio-composite sample’s hardness increased under the density and void volume fraction values, with 0.8 wt% composite sample showing the superior micro-hardness. A positive correlation was observed between the ZnO nanoparticle weight percentage and thermal conductivity, with improve nanoparticle content leading to improved thermal performance. Composites containing 0.4 wt percent nanoparticles showed superior tensile strength (66.8–84.16 MPa), flexural strength (97.69–120.02 MPa) and flexural modulus (3.56–7.68 GPa). It has been observed that the weight percentage of IDZO filler greatly influences the sound absorption efficiency of the current composites. These findings highlight the promising potential of these novel biocomposites in advanced engineering applications, emphasizing their usefulness in demanding environments with biodegradability and high-performance thermal, mechanical, and acoustic properties. Based on the sound transmission class ratings, the sisal fiber biocomposites have been regarded as great adoptions for use as sound-absorbing materials such as wall partitions, doors, enclosures, and structural components, thermal insulation systems, and electrical insulation.

Understanding AFM-IR Signal Dependence on Sample Thickness and Laser Excitation: Experimental and Theoretical Insights.

Photothermal induced resonance (PTIR), also known as atomic force microscopy-infrared (AFM-IR), enables nanoscale IR absorption spectroscopy by transducing the local photothermal expansion and contraction of a sample with the tip of an atomic force microscope. PTIR spectra enable material identification at the nanoscale and can measure sample composition at depths >1 μm. However, implementation of quantitative, multivariate, nanoscale IR analysis requires an improved understanding of PTIR signal transduction and of the intensity dependence on sample characteristics and measurement parameters. Here, PTIR spectra measured on three-dimensional printed conical structures up to 2.5 μm tall elucidate the signal dependence on sample thickness for different IR laser repetition rates and pulse lengths. Additionally, we develop a model linking sample thermal expansion dynamics to cantilever excitation amplitudes that includes samples that do not fully thermalize between consecutive pulses. Remarkable qualitative agreement between experiments and theory demonstrates a monotonic increase in the PTIR signal intensity with thickness, with decreasing sensitivities at higher repetition rates, while signal intensity is nearly unaffected by laser pulse length. Although we observe slight deviations from linearity over the entire 2.5 μm thickness range, the signal's approximate linearity for bands of sample thicknesses up to ≈500 nm suggests that samples with comparably low topographic variations are most amenable to quantitative analysis. Importantly, we measure absorptive undistorted profiles in PTIR spectra for strongly absorbing modes, up to ≈1650 nm, and >2500 nm for other modes. These insights are foundational toward quantitative nanoscale PTIR analyses and material identification, furthering their impact across many applications.

In-situ monitoring of changes in temperature and microstrain during the chemical corrosion of stone cultural relics

Temperature changes during the chemical corrosion of stone cultural relics affect the condensation and evaporation of water and chemical reactions between soluble substances and corrosive solutions. This ultimately leads to changes in the internal structure and composition of the artifacts, which in turn lead to changes in the microstrain of cultural relics. To obtain in-situ real-time information on changes in the temperature and microstrain of stone cultural relics during chemical corrosion damage, a fiber Bragg grating (FBG) detection system was developed. The detection principle for the temperature and microstrain of sandstone was provided. Thermal field emission scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry were used to characterize the surface morphology, composition, and pore structure of the sandstone samples, respectively. The temperature and microstrain changes of the sandstone samples under deionized water with different acidic/alkaline and salt solutions and at different temperatures were examined online in situ using the FBG measurement system. The results indicate that the dissolution of sandstone in the acidic solution (H2SO4 and NaHSO4) resulted in an exothermic chemical reaction as well as the dissolution of sandstone in the neutral salt solution (Na2SO4) and alkaline solution (NaOH and Na2CO3) led to material conversion and exothermic chemical reaction; the deionization reaction belongs to the dissolution reaction. The NaHSO4 solution caused the most serious corrosive disease on the sandstone surface. When the temperature of the NaHSO4 solution was 60 °C, the temperature and microstrain of the sandstone reached 63.9 °C and 253.6 με, respectively. The results of this study can support the research of revealing the corrosion mechanism of sandstone in different environments.

4D-XCT monitoring of void formation in thick methacrylic composites produced by infusion

Void formation in fibre-reinforced polymer composites processed by liquid moulding is a persistent issue in composite research and development. Not only may several void formation mechanisms come into play, but these defects can also accumulate and grow over the course of the manufacturing process. Mitigation methods can be applied once the underlying causes of voiding are identified, which is impossible through post-mortem characterisation. Here, void formation is dynamically monitored in miniaturised glass fibre-reinforced thermoplastic polymer composite samples manufactured by vacuum infusion and in-situ polymerisation, using laboratory-based X-ray computed tomography (XCT). The method allows the characterisation of the evolution of void patterns as the resin polymerises and cools down within the fibre preform. With a time resolution of 2 min and a voxel size close to 20 µm, this first-of-a-kind XCT experiment provides insights into the evolution of the void volume fraction, void size and location. The root causes leading to void formation in the system of interest were successfully identified as a combination of flow-related air entrapment during preform filling and, mostly, of chemical shrinkage of the matrix upon polymerisation. Additionally, thermal shrinkage during the cooling of the preform results in a slight decrease in the final void volume fraction.

Adaptive Reuse of Waste Plastic as Binders in Composites for Sustainable Construction

Effective and efficient handling of solid waste remains a significant issue, particularly in low- and middle-income countries, and densely populated urban areas. Waste plastic is identified as a major contributor to solid waste streams. This study highlighted the viable reuse of waste Linear low-density polyethylene (LLDPE) plastic as a binder and full replacement for cement in composite blocks. An extrusion technique was adopted to melt the plastic and mix it with the sand fillers to create a homogenous waste plastic binder composite block. Composite block samples were produced at various mixture ratios of 1:1, 1:2, and 1:3 with waste plastic or cement as binder and sand as filler. The composite samples' compressive strength, flexural strength, tensile strength, UPV, thermal conductivity, skid resistance, Cantabro mass loss, and morphology were investigated. In addition, the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis of the composites were carried out. The results showed that composite blocks containing waste LLDPE plastic as binder exhibited lower compressive strength, higher flexural strength, and tensile strength, better thermal insulation, and abrasion resistance compared to composite blocks containing cement as binder. Meanwhile, the cement binder composite gave better skid resistance when the surface was wet than the waste plastic binder composite. However, the waste LLDPE plastic composite mixes considered gave compressive strength above 5 N/mm2, which is the minimum requirement for building bricks according to BS 3921: 1985.

Experimental analysis of tensile strength of 6-layer carbon/kevlar/epoxy hybrid composite reinforced with nano-graphene/silica nanoparticles

The main aim of the present research is to improve the static tensile strength of Carbon/Kevlar/Epoxy hybrid composite by adding different nanoparticles. To this end, two well-known nanoparticles namely Nano-Silica and Nano-Graphene were considered. Also, the total percentage of adding nanoparticle reinforcing elements to the hybrid composite was considered equal to 1.5%. In this way, five categories of reinforced hybrid composites, including 0%Nano-Silica+0%Nano-Graphene, 1.5%Nano-Silica+0%Nano-Graphene, 1.2%Nano-Silica+0.3%Nano-Graphene, 1.0%Nano-Silica+0.5%Nano-Graphene, and 0.75%Nano-Silica+0.75%Nano-Graphene, were studied. Composite samples were prepared using manual layout technique and tensile tests were performed according to the ASTM standard. It was found that the tensile strength increases with the addition of nanoparticles to the Carbon/Kevlar/Epoxy hybrid composite, but these two do not always have a direct and linear relationship with each other. Moreover, it was shown that the addition of 1.2% silica nanoparticles and 0.3% nanographene leads to an increase of tensile strength up to 36%, and this is the best optimal percentage of additive nanoparticles in this research.

Synthesis of titanium-vanadium oxide thin films through thermal oxidation process for their use in CO gas sensing application

The thermal oxidation of evaporated titanium-vanadium thin films was carried out at different post-annealing temperatures. The structural, morphological, compositional, optical, electrical, and gas sensing properties of titanium-vanadium oxide thin films were primarily investigated. The results of the XRD study and Raman spectroscopy verified the presence of the orthorhombic V2O5, tetragonal TiO2, and monoclinic V2Ti3O9 phases. The crystallinity of TVO thin films was improved at higher annealing temperatures. The grain size (seen from SEM images) and oxygen compositions (obtained from EDS measurement) of TVO samples are also enhanced when the post-annealing temperature is increased from 500 to 575°C. From the transmittance curves, the bandgap values for TVO samples were estimated and found in the range of 2.14 to 2.36 eV. The n-type conductivity of TVO films was confirmed by the negative Hall coefficient values. At last, the CO gas sensing response of TVO thin films was analyzed by monitoring the change in the surface electrical resistances at different operating temperatures and CO gas concentrations. The dynamic and static resistances were assessed at different operating temperatures varying from 100 to 300°C. The TVO sample prepared at 550°C showed the best conditions by examining the materials and CO sensing properties.