Water Mass Loss Research Articles

Development of an antimicrobial tissue conditioner with quaternary ammonium methacryloxy silane (K18): An in vitro study.

To determine the effects of K18 quaternary ammonium methacryloxy silane (QAS) on tissue conditioner materials and their antimicrobial properties. 30% K18 QAS in methyl methacrylate (MMA; K18-MMA; 0%, 15%, and 20% w/w) was incorporated into a commercial tissue conditioner (Coe comfort). The degree of curing (Shore A hardness), hydrophilicity (contact angle), flow, liquid sorption, mass loss, and antimicrobial properties of Streptococcus mutans, Streptococcus sanguinis, and Candida albicans were determined. Statistical analysis included analysis of variance with Tukey HSD and Kruskal-Wallis with Bonferroni correction. Hardness increased significantly at higher K18-MMA concentrations. The contact angles did not differ between the groups. Although the control and K18-containing tissue conditioner flow decreased significantly at each successive time point and with increasing K18 QAS MMA concentration, the flow was still within the ISO 10139-1 specifications for class 2 (high-flow) soft lining materials until 2 min 30 s. The highest liquid sorption happened between 1 and 4 weeks. The controls absorbed more acid than water or base, and the K18 groups absorbed more water and acid than base. With increasing K18-MMA concentration, the mass loss increased at all times and in all three media, except in base, after 4 weeks. Both 15% and 20% K18-MMA showed significant antimicrobial activity against S. mutans, S. sanguinis, and C. albicans. K18-MMA imparted significant antimicrobial properties to tissue conditioners against S. mutans, S. sanguinis, and C. albicans without compromising the flow, hardness, or hydrophilicity. However, K18-MMA addition led to increased water sorption and mass loss after 4 weeks.

Performances of starch foam improved by an alginate coating

This research aims to develop an environmentally friendly food packaging based on starch foam coated with alginate. The foam was coated with various concentrations of an alginate solution (0, 0.5, 1.0, 1.5, and 2.0 %w/v). The effects of these coatings on the properties of starch foam were then investigated. The results showed that the alginate coating increased the density of the starch foam. Starch foam coated with the alginate solution at a concentration of 1.0 %w/v showed the optimum flexural stress at maximum load (4.72 MPa), hardness (96), and mass loss in water (5.51 %). These results showed significant improvements in these properties by comparison with the uncoated foam. The alginate coating slightly improved the thermal stability of the starch foam and did not significantly delay the biodegradation of the starch foam in soil. In conclusion, coating starch foam with an alginate solution presents a viable approach to developing sustainable food packaging materials with enhanced mechanical and water resistance properties.

Impact of graphite nano/microplatelets on the mechanical and durability performance of concrete by incorporating mill scale waste

AbstractGraphite nano/microplatelets (GNMPs), which are part of the tetral family (group 14 elements), exhibit significant potential to enhance the mechanical and durability attributes of concrete due to their multi-functional filler properties. Mill scale waste (MSW), is a residual byproduct of the steel industry that can be used in concrete as a replacement for sand, thereby avoiding pollution and depletion of natural resources of aggregates. Although (GNMPs) enhance some of the mechanical properties of concrete and (MSW) has also impact on concrete properties, no information is available, particularly on the influence of both (GNMPs) and (MSW) in concrete. Therefore, in this research, an innovative concrete was prepared by using varying amounts of GNMPs (0%, 0.1%, 0.2%, 0.3%, and 0.4% by weight of cement) and replacement of sand with MSW (0%, 25%, 50%, and 75% by weight of sand). These concrete mixes were tested for properties such as workability, density, compressive strength, splitting tensile strength, flexural strength, and durability. Tests including bulk water sorption and acid attack resistance were conducted on the concrete specimens. The microstructural analysis of concrete with GNMPs and MSW was carried out through scanning electron microscopy (SEM). Results indicated that the addition of (GNMPs) and (MSW) increased concrete density and decreased its slump value when compared to the control mix. The compressive, splitting, tensile, and flexural strengths of the mixes were increased at specified proportions of up to 0.3% GNMPs and 50% MSW content. It also resulted in a reduction of water sorptivity, mass, and compressive strength loss against acid attack. The results demonstrated that MSW and GNMPs can be utilized in concrete for sustainable construction practices.

Quantifying Salt Crystallization Impact on Evaporation Dynamics From Porous Surfaces

AbstractWe investigated the effects of salt crystallization on the dynamics of saline water evaporation in porous media. Water mass loss rates from sand columns supplied with NaCl solutions at three concentrations were monitored under controlled ambient conditions. The formation and evolution of salt crystals over sand surfaces were synchronously imaged optically and thermally. Despite identical experimental and ambient conditions, we observed distinct crystallization dynamics that affected evaporative mass loss rates for similar salt concentrations, highlighting high variability of crystallization and its impact on evaporation. We observed the enhancement of maximum evaporation rates by factors of 3 to 14 under our experimental conditions and attributed this enhancement to the formation and evolution of porous crystalized salts at the surface. Additionally, visible intermittent temperature fluctuations of the salt crust were quantified using thermal imagery attributed to the dynamic processes of crystallization, dissolution and evaporation occurring simultaneously at the surface.

Harnessing artificial neural networks and linear regression models for modeling thermal modification processes: Characterization by FTIR and prediction of the mechanical properties of eucalyptus wood

In the present study, an artificial neural network model and multiple linear regression method were constructed to establish a relationship between the parameters of the thermal modification process and the mechanical properties of Eucalyptus camaldulensis wood samples. Three influencing parameters on the mechanical properties during heat treatment were considered input variables, namely water absorption, volumetric mass, and mass loss; the other parameters were kept constant (treatment temperature: 200, 220, 240, and 260 °C, and the duration: 5, 60, and 90 minutes). There were five neurons in the hidden layer that were used, as well as an output layer for the mechanical property. According to the results obtained, the mean square error (MSE) for the training, validation, and testing datasets were determined to be 0.21, 0.25, and 0.22 in the prediction modulus of rupture (MOR) and 0.019, 0.017, and 0.023 in the prediction modulus of elasticity (MOE). Higher coefficients of determination (R2) ranging from 0.93 to 0.98 were obtained for all datasets with the proposed ANN models, while the multiple linear regression models found the MSE to be 1.03 and 1.40 for MOR and MOE, respectively, as well as R2 to be 0.97 and 0.80, respectively. These results show that ANN models can be successfully used to predict the change in mechanical properties of wood during heat treatment.

Shrinkage and Creep Properties of Low-Carbon Hybrid Cement.

Hybrid cements combine clinker with large amount of supplementary cementitious materials while utilizing hydration and alkali activation processes. This paper summarizes shrinkage and creep properties of industrially produced H-cement, containing only 20% of Portland clinker. In comparison with a reference cement CEM II/B-S 32.5 R, autogenous shrinkage is smaller after 7 days, and drying shrinkage is similar at similar times. A different capillary system of H-cement leads to faster water mass loss during drying. Basic and total creep of concrete remains in the standard deviation of B4 and EC2 creep models. The results demonstrate that shrinkage and creep properties of concrete made from H-cement have similar behavior as conventional structural concrete or high-volume fly ash concrete.

Augmenting interfacial solar steam generation using 3D-printed hollow honeycomb structured pattern filled with rGO decorated natural fibres

In the present study, a hollow honeycomb structured (HHS) pattern is fabricated using fusion deposition modelling and filled with different natural fibres namely sugarcane (SC) and cotton sponge (CS). It is then called HHS-SC and HHS-CS interfacial solar evaporators. In addition, reduced graphene oxide (rGO) nanomaterial is coated on the top evaporative surface of the developed evaporators to investigate the performance of interfacial solar steam generation (ISSG). During experimentation, HHS-CS/rGO evaporator exhibits better performance than HHS-SC/rGO evaporator. At indoor conditions, mass loss of water (MW), evaporation flux (EF) and evaporation efficiency (EE) of the HHS-CS/rGO evaporator are 2.0 g, 3.493 kg/m2h and 84.04 % respectively. Consequently, the MW, EF and EE are 6.2 g, 1.35 kg/m2h and 61.29 % respectively at outdoor conditions. Results show that (i) the reduction in the size of porosity and improved capillary action of CS (ii) the super hydrophilicity nature of CS increases the water transportation (iii) the poor thermal conductivity of CS (iv) the higher thermal conductivity of rGO aids in trapping the sunlight. The stability and repeatability of the HHS-CS/rGO evaporator are investigated and found to be excellent for 8 repetitive cycles. Additionally, the prepared interfacial solar evaporator results better performance in dye molecule separation and salt water purification and hence, this can be recommended for commercial applications.

Testing triple oxygen isotope preservation in the new OPEnS totalizer against conventional monthly rainfall collectors

Understanding the mechanisms that drive spatial and temporal triple oxygen isotope (Δ′17O) variations in modern precipitation is the first step to expanding the utility of these measurements as an environmental tracer jointly with traditional stable isotope parameters δD, δ18O, and d-excess. However, “totalizers” designed to collect a single precipitation sample pooled over a calendar month and minimize evaporation and associated isotopic fractionation of the sample during that time have not been tested for Δ′17O. We conducted a 30-day laboratory experiment comparing mass losses and isotopic shifts in four totalizers: 1) the OPEnS (Openly Published Environmental Sensing) totalizer, 2) the classic oil-based totalizer, 3) the commercial tube dip-in/pressure equilibration totalizer (Palmex Ltd. RS1), and 4) a reference totalizer (the control, lacking any evaporation reduction mechanism). The OPEnS totalizer was designed as being readily user built with parts costs of about $10, oil-free to facilitate quick and easy sample preparation and risk-free sample analysis, and its collection device expands as it fills to maintain a small gas/water ratio and minimize internal evaporative losses. All totalizers were filled to 12 % of their 3-L volume and placed in a modified laboratory oven with a diurnal temperature change of 23 to 40 °C and an average relative humidity of 9.1 % to simulate extreme evaporative conditions. The OPEnS totalizer experienced the smallest mass loss of water (0.21 %) and smallest isotopic shifts (p < 0.05 for δ18O and d-excess), which were all within measurement error. The oil, tube, and reference totalizers showed larger mass losses (0.41, 1.37, and 1.61 %, respectively) and evaporative enrichment with respect to δD (+0.3, +0.8, and + 2.1 ‰), δ18O (+0.16, +0.23, and + 0.83 ‰), and d-excess (−0.9, −1.0, and − 4.5 ‰). The Δ′17O variations for all totalizers were within measurement error, so we suggest that in less harsh climates their triple oxygen isotope changes during secondary evaporation would be more acceptable. To test the OPEnS totalizer in field settings, we installed it alongside oil totalizers to collect monthly precipitation over three years in the towns of Jolly and San Antonio, Texas, with mean annual precipitation, temperature, and windspeed values of 556 and 563 mm, 18.7 and 21.9 °C, and 5.0 and 3.5 m/s, respectively. Results indicate that the OPEnS and oil totalizers can produce similar isotopic data in the field, but modifications to OPEnS have been implemented to minimize under-catch and stabilize the collection component where high winds are present and additional testing under a variety of environmental conditions is ongoing. OPEnS is scalable according to expected monthly precipitation amounts, providing a cost-effective, high-performance device for quantification of total rainfall and its isotopic composition without oil contamination risks.

Characterization of PLGA versus PEG-PLGA intracochlear drug delivery implants: Degradation kinetics, morphological changes, and pH alterations

Drug delivery to the inner ear presents a unique challenge due to the complex inner ear anatomy and its tight physiological barriers. This study investigates the degradation behavior of intracochlear drug delivery implants (IDDI) composed of dexamethasone and poly(lactic-co-glycolic acid) (PLGA) or polyethylene glycol–poly(lactic-co-glycolic acid) (PEG-PLGA), respectively. IDDI were incubated in artificial perilymph and implants' degradation kinetics, morphological changes, water uptake behavior, and pH alterations were assessed. Microscopy revealed significant changes in appearance, with PLGA IDDI exhibiting rapid expansion, reaching up to 183 % in diameter and 185 % in length. PEG-PLGA implants showed gradual expansion, reaching a maximum of 178 % in diameter and 144 % in length. Despite these morphological changes, the IDDIs could still be applicable in terms of cochlear dimensions in combination with cochlear implants (CI) in humans or in a domestic pig animal model. Scanning electron microscopy analysis demonstrated surface alterations of PLGA implants, while PEG-PLGA implants remained shape-stable. Gravimetric analysis and gel permeation chromatography revealed distinct degradation profiles, with PLGA implants displaying rapid water uptake and mass loss, while PEG-PLGA implants showed delayed water uptake and minimal mass reduction. pH measurements using the pH-sensitive fluorescent dye SNARF™-1 showed initial pH reduction in artificial perilymph for PLGA implants while PEG-PLGA implants maintained pH stability.

Characterization of Moroccan cactus juice toward its use as a green flocculant in wastewater treatment

ABSTRACT The present work is dedicated to the characterization of Moroccan cactus juice, which shows encouraging performance in wastewater treatment. Various techniques were used to highlight the chemical and physical properties of this natural product. Elemental analysis of cactus juice using inductively coupled plasma emission spectroscopy revealed the presence of numerous minerals. Fourier Transform Infrared, ultraviolet, and nuclear magnetic spectroscopies demonstrate the presence of many carbohydrate components. Identification of volatile compounds by gas chromatography reveals the presence of Gibb-3-ene-1,10-dicarboxylic acid, ethyl gallate, 3TMS derivative, ethyl ester and 1-(2-Isopropyl-phenyl)-3,6,6-trimethyl-1,5,6,7-tetrahydro–indazol. Thermogravimetric analysis indicates three peaks at 100, 200 and 600 °C, corresponding to the mass loss of water, polysaccharides, and organic matter, respectively. The rheological characterization of cactus juice suggests that this liquid exhibits shear-thinning behavior, which is governed by the Casson model. The results of the Zeta potential measurement demonstrate the anionic character of cactus juice as a flocculant, with −25 mV as a value of zeta potential. Its use as a flocculant in organic matter removal shows that the chemical Oxygen demand decreases significantly with the increase of the added cactus juice dose, confirming, therefore, its flocculating behavior.

Recycled foam concrete masonry and porcelanite rocks-based lightweight geo-polymer concrete at elevated temperatures

This study investigated the mechanical and microstructural properties of lightweight aggregate geo-polymer concrete (LWAGC) produced by alkali-activating glass powder (GP) and Fly Ash (FA) at elevated temperatures ranging from 200 to 800°C. It also examined the effects of incorporating crushed foam masonry (RFA) and crushed porcelanite rock aggregates (PA) into FA and GP-based geo-polymer concrete, both before and after exposure to ambient and high temperatures. A low-calcium type of FA was used as a binder in the geo-polymer concrete paste, with a 10 % replacement of glass powder. The concrete samples were heated at temperatures of 200°C, 400°C, 550°C, and 800°C for a duration of 60 minutes, with a heating rate of 7°C per minute. It was observed that the inclusion of weaker coarse aggregate resulted in a reduction of the compressive strength of the concrete. The geo-polymer concrete was subjected to tests for water absorption, mass loss, cracking, and microstructure analysis at elevated temperatures. The findings indicate that at heating temperatures of 400°C and above, the geo-polymer concrete underwent degradation and dehydration. The test findings also revealed residual compressive strengths of 104.9 %, 97.2 %, 81.8 %, and 64.2 % for the (RFA) types, and 107.3 %, 94.8 %, 78.3 %, and 58.8 % for the (PA) types. Additionally, the density decreased by 1.02 %, 4.88 %, 8.10 %, and 13.88 % for (RFA) and (PA) types, respectively, and by 0.27 %, 1.91 %, 4.67 %, and 10.79 % overall. The results indicate that the compressive strength of the concretes increased after exposure to elevated temperatures of 35°C and 200°C. However, when exposed to temperatures ranging from 400°C to 800°C, the strength of the LWAGC started to degrade and decline. Based on the obtained findings, the present study recommends performing laboratory tests on construction waste generated during demolition while developing and evaluating numerical models that predict the behavior of the resulting demolition materials when incorporated in the production of geo-polymer concrete.

MULTIDIMENSIONAL ANALYSIS OF PHYSICOCHEMICAL TRANSFORMATIONS AND SENSORY ATTRIBUTES OF GREEN AND ROASTED COFFEE

This research presents a comprehensive analysis of the physicochemical and sensory attributes of green and roasted coffee beans from Rwanda, Colombia, Ethiopia, and Peru. Advanced image processing tools were utilized for defect analysis. Water activity, pH, mass loss, and moisture were determined, and thermal analysis were performed. Substantial variations in physicochemical properties were found among coffee beans of different origins. Utilizing a multi-objective optimization algorithm, Ethiopian coffee emerged as possessing the most optimal physicochemical characteristics. The optimal roasting temperature range for Ethiopian coffee was found to be 216.49 °C to 230.15 °C, with longer roasting times at lower temperatures producing more evenly roasted coffee. This study provides valuable information to coffee producers and processors to optimize the roasting process and improve coffee quality.

Study of the effect of heat temperature on the chemical changes and hygroscopicity of eucalyptus wood by FT-IR and prediction of mechanical properties by the MLR regression method

This study describes the effect of heat treatment on some physical, chemical, and mechanical properties of Eucalyptus Camaldulensis (EC) wood at different temperatures and treatment times (200 °C–260 °C for 5, 60, and 90 min). The evaluation of hygroscopic properties was determined by relative humidity, mass loss, dimensional stability tests, and density. The results showed that the heat treatment leads to an increase in mass loss of 5.2 %–11.9 % at 200 °C. The density changed significantly for this studied species as well as the dimensional stabilization. Chemical changes in wood structure were assessed by Fourier Transform Infrared Spectroscopy.To verify the validity of the superposition “Mass loss-Density-water absorption” on the mechanical properties (modulus of elasticity (MOE) and modulus of rupture (MOR)) during heat treatment, we have developed a mathematical model based on Multiple Linear Regression (MLR), in order to establish a relationship between the independent parameters and the dependent parameters (MOE and MOR). The evaluation of the quality of the models developed was based on several statistical tools, namely R = 0.99, R2 = 0.99, R2adj = 0.98, and F = 132.33. The results demonstrated that elaborate models of mechanical properties have a high predictive capacity (MOR and MOE). The wood’s carbohydrates (particularly hemicelluloses) are then degraded during the heat treatment. The % of carbon increases from 47.8 to 49.8 %, which is proportional to mass loss, while the % of oxygen decreases by 46.1 %, which is inversely proportional to mass loss. Furthermore, FTIR analysis revealed that the effect of heat-treated wood chemical changes was related to the hydroxyl OH function of cellulose, functional groups, and aromatic system of lignin. In conclusion, the results demonstrated that at 200 °C, heat treatment caused a 5.2–11.9 % increase in mass loss; dimensional stability and density underwent considerable changes. FTIR spectroscopy confirmed the chemical changes in the wood structure during heat treatment. Furthermore, the “MLR” mathematical model showed that density contributed to the increase in MOR and MOE properties, while water absorption and mass loss contributed to the decrease in MOR and MOE properties. Finally, the % of oxygen decreased by 46.1 %, which is inversely proportional to the loss of mass, and the % of carbon increased from 47.8 % to 49.8 %, which is proportional to the loss of mass.

Enhancing interfacial solar steam generation using hybrid (Co3O4/perovskite structured NaTaO3) nanomaterials coated on cotton cloth with sawdust composite evaporator

Interfacial solar steam generation (ISSG) is an emerging technology, used for the replenishment of water scarcity on the globe. In ISSG process, an interfacial evaporator is allowed to float on the bulk water surface to produce steam. Here, the different interfacial evaporators such as cotton cloth (CC), epoxy+hardener+sawdust (EHS) composite covered with cotton cloth (E-CC), EHS composite covered with Co3O4 coated cotton cloth (E-CC/Co3O4) and EHS composite covered with hybrid nanomaterial (Co3O4/ NaTaO3) coated cotton cloth (E-CC/hy1 and E-CC/hy2) are developed and experimented under 1 sun illumination. The synthesized NaTaO3 and Co3O4 photothermal materials are characterized using UV, XRD, FT-IR, FE-SEM, TEM and TGA respectively. Among all the evaporators, E-CC/hy2 attains an outstanding mass loss of water, evaporation rate and evaporation efficiency of 5.7 g, 4.92 kg m−2 h−1 and 117.78% respectively. In addition, the ion concentration of the condensed water is measured and found to be below WHO standards. Also, the dye degradation level of four different dyes is experimentally studied and found to be excellent dye degradation level for all the tested samples. The obtained results are mainly due to (i) the coating of Co3O4/ NaTaO3 composite over the top surface of the evaporator that traps the solar light efficiently (ii) the improved surface roughness that reduces the scattering and reflection of solar light (iii) the presence of excellent hydroxyl water absorbing groups in cotton cloth and better refilling of water at the evaporative surface of the evaporator (iv) low thermal conductivity of cotton cloth and EHS evaporator that inhibits the heat travel to the bulk water and glass beaker though conduction and convection.

Durability properties of basalt fiber-reinforced mortars with different mineral admixtures exposed to high temperatures

This study investigated the durability properties of mortars containing basalt fiber and various mineral admixtures against high temperatures. Different types of mortar samples were produced with basalt fiber, metakaolin, silica fume and fly ash. The samples were exposed to temperatures of 400 °C, 600 °C and 800 °C. Residual compressive strength, flexural strength, ultrasonic pulse velocity, mass loss, water absorption, capillary water absorption and microscope analysis tests were carried out. Test results revealed that basalt fiber improved the residual durability properties of the mortars exposed to high temperatures. Basalt fibers exhibited bridging behavior and prevented high temperature-induced cracks. Basalt fibers showed excellent consistency with all three mineral admixtures, and the mineral admixtures increased the contribution of basalt fiber to durability properties. Because of this harmony, basalt fiber-reinforced and mineral admixture-added samples had 86.42% greater residual compressive strength and 144.42% greater flexural strength than the control samples. The void-free internal structure provided by mineral admixtures increased the effect of BF and significantly reduced water absorption, capillary water absorption and mass loss values. UPV tests and microscopic analysis revealed that basalt fiber and mineral admixtures reduced high temperature-induced cracks.

Seville history insight through their construction mortars

Seville is intimately linked to its historic role and extensive cultural heritage. The city has been occupied by Romans, Arabs and Christians, who built important historical buildings. Roman (first–second centuries) and Arabic (eleventh century) buildings, medieval Shipyard (thirteenth century), San Isidoro and Santa Maria de las Cuevas monasteries (fifteenth century), Santa María de las Cuevas (fifteenth century modified in eighteenth century), El Salvador Church (eighteenth century), the Royal Ordnance building (eighteenth century) and Santa Angela de la Cruz convent (twentieth century) performed with lining mortars, and mortars used in building stones (City Hall and Marchena Gate), all of them located in Seville (Spain), have been studied. Ninety-four mortar samples (employed as structural, plaster, coating) originally used or applied in restoration processes have been collected to perform an archaeometry study. The ratio of CO2 mass loss to hydraulic water (H2O) mass loss, and the mineralogical characterization by X-ray diffraction has been used to compare the mortars used in the different historical periods. Mainly hydraulic mortars were widely used in all these studied monuments as most mortars showed CO2/H2O ratios within the 4–10 range. Moreover, the thermal analysis curves also showed a broad temperature range for the thermal decomposition of the carbonate fraction of the mortars.

Silica Aerogel-Polycaprolactone Scaffolds for Bone Tissue Engineering.

Silica aerogel is a material composed of SiO2 that has exceptional physical properties when utilized for tissue engineering applications. Poly-ε-caprolactone (PCL) is a biodegradable polyester that has been widely used for biomedical applications, namely as sutures, drug carriers, and implantable scaffolds. Herein, a hybrid composite of silica aerogel, prepared with two different silica precursors, tetraethoxysilane (TEOS) or methyltrimethoxysilane (MTMS), and PCL was synthesized to fulfil bone regeneration requirements. The developed porous hybrid biocomposite scaffolds were extensively characterized, regarding their physical, morphological, and mechanical features. The results showed that their properties were relevant, leading to composites with different properties. The water absorption capacity and mass loss were evaluated as well as the influence of the different hybrid scaffolds on osteoblasts' viability and morphology. Both hybrid scaffolds showed a hydrophobic character (with water contact angles higher than 90°), low swelling (maximum of 14%), and low mass loss (1-7%). hOB cells exposed to the different silica aerogel-PCL scaffolds remained highly viable, even for long periods of incubation (7 days). Considering the obtained results, the produced hybrid scaffolds may be good candidates for future application in bone tissue engineering.

Degradation by Electron Beam Irradiation of Some Elastomeric Composites Sulphur Vulcanized.

Composites based on natural rubber and plasticized starch obtained by the conventional method of sulfur cross-linking using four types of vulcanization accelerators (Diphenyl guanidine, 2-Mercaptobenzothiazole, N-Cyclohexyl-2-benzothiazole sulfenamide, and Tetramethylthiuram disulfide) were irradiated with an electron beam in the dose range of 150 and 450 kGy for the purpose of degradation. The vulcanization accelerators were used in different percentages and combinations, resulting in four mixtures with different potential during the cross-linking process (synergistic, activator, or additive). The resulting composites were investigated before and after irradiation in order to establish a connection between the type of accelerator mixture, irradiation dose, and composite properties (gel fraction, cross-linking degree, water absorption, mass loss in water and toluene, mechanical properties, and structural and morphological properties). The results showed that the mixtures became sensitive at the irradiation dose of 300 kGy and at the irradiation dose of 450 kGy, and the consequences of the degradation processes were discussed.

Performance evaluation of concrete with waste glass after elevated temperatures

Recycling waste glass (WG) to produce concrete is a crucial step towards building sustainability. In this paper, a new approach of substituting coarse aggregate (CA) and fine aggregate (FA) with crushed glass (CG) and glass powder (GP) respectively was proposed to investigate the effect of different CG and GP replacement rates on the performance of concrete after high temperature. A total of 10 groups of mix proportions were designed, and the substitution rates of GP and CG varied from 0 to 30 % by volume. The specimens were heated from 20 °C to 600 °C at a rate of 5 °C/min. After reaching target temperature, they were kept for 2 h and naturally cooled to ambient temperature. Subsequently, mixtures were tested to evaluate the apparent changes, weight loss, volume change, ultrasonic pulse velocity (UPV), damage degree, dynamic elasticity modulus, compressive strength and split-tensile strength before and after high temperature. Results show the compressive strength increased by 3 %-6% from 20 °C to 150 °C, then gradually decreased and a strength loss of 30–40 % was observed after 600 °C. Whereas the splitting tensile strength continued to decline as rising temperature, with a 60 %-70 % change in strength loss after 600 °C. Concrete with 10 % GP substitution and 10 %-20 % CG substitution exhibited better performance in this experiment at room temperature and high temperature in terms of mechanical, physical and durability properties compared to others. Besides, as raised temperature, an increase in water absorption and mass loss was observed for all mixtures, while the UPV reduced until it became doubtful. In conclusion, the combined substitution of CG and GP for natural aggregates can improve the performance of concrete after elevated temperature.

Evaluation of the spatial variation in moisture content inside wood pieces during drying by NIR spectroscopy

Abstract The moisture content (MC) of wood affects its industrial performance, but it is difficult to monitor spatial variations in MC. Here, a multivariate regression was developed to estimate the MC from near infrared (NIR) spectra and was used to monitor the spatial variation in the MC of wood during air- and oven-drying. The spectra and mass of wood pieces were measured at five stages during drying (at each 20% loss of initial water mass). Wood pieces were dried naturally and oven-dried at 60 °C. Initially, 25 spectra were recorded at equidistant points covering the entire longitudinal × radial surface of the sample. Then, a planing machine was used to access the inside of the wood, and NIR spectra were measured for each new surface, at a total of 100 points spatially distributed within the wood pieces. The wood pieces were analyzed in their original state, and when they had lost 20, 40, 60, and 80% of their initial water mass. An NIR-based regression (R 2 p = 0.90 and RMSEP = 10.51%) was applied to estimate the MC, and its spatial gradient during drying was then mapped. These analyses revealed the spatial variation in MC within wood pieces during drying.