Elastic Values Research Articles

Effects of Sugarcane Bagasse Fiber Additives on the Mechanical Properties of Lime-Based Composites and their Compatibility with Traditional Lime-Based Mortars

This study explored the incorporation of sugarcane bagasse fibers into lime mortars to potentially enhance the mechanical properties and durability of materials used in heritage structures made of unreinforced masonry. Assessment of the mixes and their compatibility with the traditional lime mortar mix used in conservation projects in the Philippines was also performed. Five (5) mortar specimen types containing different fiber content were prepared, each with twelve (12) samples. Flexural strength, compressive strength, ductility, and modulus of elasticity comprise the mechanical properties investigated while visual properties, chemical and mineralogical composition, pore space, mechanical properties, and hydrophilic behavior comprise the criteria for computing incompatibility degrees (IDs). Being the mix traditionally used in local conservation works, Mortar L0 (plain mortar) served as the control. Results showed that Mortars L4.6 (4.6% fiber content), L7.6 (7.6% fiber content), and L10.7 (10.7% fiber content) generally had lower mechanical properties compared to Mortar L0, except for the 14% increase observed in the compressive strength of Mortar L4.6. Mortar L1.5 (1.5% fiber content) had the best results having significant improvement in overall mechanical strength. It exhibited 6.8% increase in flexural strength, 38% increase in compressive strength, and 69.4% increase in modulus of elasticity values. Mortars L1.5, L4.6, L7.6, and L10.7 were computed to have IDs equal to 3.6, 1.1, 1.8, and 3.3, respectively. These indicate low to medium low incompatibility with Mortar L0. These findings highlight the viability of sugarcane bagasse fibers as reinforcement for lime mortars while maintaining sufficient compatibility with traditional lime mixes.

Investigation of the Role of Shear Deflection in the Flexural Performance of Structural Insulated Panels

Abstract As a material used in building construction, structural insulated panels (SIPs) deflect under flexural loading and creep over time. This work examines the deflection behavior of full-scale SIPs that were tested in bending. Approximately half of the matched specimens were tested after production and the other half were tested after a 90-day creep test. Of primary interest was the deflection behavior of the SIPs under load. After testing, the deflection was apportioned between the bending stiffness of the oriented strand board (OSB) and the shear modulus of the foam. Results indicated that when the known OSB modulus of elasticity values of 664,000 psi and 931,000 psi were considered among the different SIP thickness and treatments (with and without creep testing), the shear-based deflection from the foam ranged from 44 to 73 percent of the overall deflection. The calculated foam modulus of rigidity decreased slightly but significantly after creep testing. Also, the shear-based foam deflection increased slightly but significantly after creep testing.

Evaluation of Kidneys with Renal Doppler Ultrasonography and Ultrasound Elastography in Patients with Type 2 Diabetes Mellitus

Introduction: The aim of this study early recognize diabetic nephropathy by ultrasound elastography.This study was to predict the possibility of developing diabetic nephropathy without the need for renal biopsy. Methods:This study included 100 patients and 100 healthy volunteers. Shear wave elastography examination were taken of the renal parenchyma and the Resistive Index values were taken renal artery. Results:.In the patient group, the elastography values were measured as 7.02±2.15 kPa in the right kidney parenchyma and 6.90±2.09 kPa in the left. In the control group, the elasticity values were measured as 4.14±0.98 kPa in the right kidney parenchyma and 4.11±0.85 kPa in the left. The RI mean values were determined as 0.59±0.05 in the right kidney and 0.59±0.04 in the left kidney in the patient group and 0.52±0.05 in the right kidney and 0.52±0.05 in the left kidney in the control group. Conclusion: The elastography values and the RI values were significantly higher in the patients with Type 2 DM than in the control group. Thus, it can be concluded that it is possible to determine renal fibrosis and predict the possibility of diabetic nephropathy development with the non-invasive methods of SWE and colour Doppler US, without the need for biopsy.

Bone cutting performance and mechanical properties of piezo-surgical tips: a nano-indentation study

Purpose: The aims of this study were to compare the mechanical properties of piezo-surgical tips such as nano-hardness, elastic modulus, surface roughness, and wear level, and to measure their cutting performance. 
 Materials and Methods: In this study, 31 piezo-surgical tips were used, three for control and 28 for testing. The testing tips were equally divided into four groups with different numbers of osteotomies: the four-, 8-, 16-, and 32-osteotomy groups. The mean osteotomy duration was recorded during osteotomy. Scanning electron microscopy images of the tips in the test groups were obtained before and after osteotomy, and the wear level of the tips was measured. 
 Results: A statistically significant increase was observed in the nano-hardness of the piezo-surgical tips depending on the number of osteotomy (for 4-use; 22.47±1.67H and for 32-use; 28.49±3.42H). The elasticity value of the testing tips was in the range of 218.55±15.74E to 241.26±10.46E, and all of the values were significantly higher than those in the control group (174.39±13.53E). As the frequency of use increased, a significant increase in surface roughness was observed (from 16.67±1.50 to 56.12±2.60). A positive correlation was found between the frequency of use and the wear level of the tips, and between the surface roughness and wear level of the tips. 
 Conclusion: With the increase in the number of osteotomies, significant changes in the mechanical and physical properties of the piezo-surgical tips that affected their bone-cutting performance were observed.

Evaluation of meniscal elasticity using shear wave elastography in obese children and adolescents: a preliminary cross-sectional study.

Musculoskeletal problems such as pain, joint pathology, increased risk of fracture, and the development of structural deformities are common in childhood obesity. Increased mechanical stress on the knee joint leads to degenerative changes in the cartilage and meniscus. Meniscal elasticity values increase in meniscal degeneration. Shear wave elastography (SWE) is an ultrasound-based imaging technique based on the principle of measuring tissue elasticity. We aimed to investigate the changes in meniscal stiffness and thickness that can be caused by obesity in children and adolescents using SWE. In this prospective cross-sectional study, the menisci of obese (n=44) and age- and sex-matched healthy weight (n=44) children and adolescents were assessed by SWE. Meniscal elasticity was measured in kPa on the coronal plane. Independent samples t-test was used to compare meniscal elasticity values between groups. Additionally, Pearson's correlation test was used to examine the relationships between elasticity values and age, height, weight, and body mass index (BMI). Meniscal elasticity values were significantly higher in the obese group than in the control group (P<0.001). In both groups, there was no significant difference in meniscal stiffness between the boys and girls or between the right and left sides. In the obese group, there were weak and moderate positive correlations between meniscal elasticity values and age, weight, and BMI (P<0.05). There was no significant difference in meniscal thickness between the obese and control groups. Meniscal stiffness is increased in obese children and adolescents.

Influence of buckwheat flour on the quality characteristics of Fatayer (pastry with zahter mixture)

In this study, the effect of the use of buckwheat flour on some quality characteristics of Fatayer which is a bakery product containing breakfast Zahter mixture as a top filling material and traditionally produced in Syria was investigated. The effect of buckwheat flour in different proportions on the physicochemical, textural, and sensory quality characteristics of Fatayer was investigated. In the study, 5 different types of Fatayers were produced with buckwheat flour ratios of 0, 30, 50, 70 and 100 % (g/g). The Fatayer produced with 100 % (g/g) wheat flour was used as a control. As the buckwheat content of Fatayers increased, the moisture content decreased from 26.61 to 14.92 % (w.b.), the fat content increased from 18.66 to 20.17 % (d.b.), and the weight loss decreased from 17.16 to 14.74 % (g/g) . The increase in the buckwheat flour ratio decreased the diameter (mm) and thickness (mm) of the Fatayers. It was observed that the increase in the buckwheat flour ratio causes an increase in hardness, flexibility, gumminess, chewiness and elasticity values, and a decrease in stickiness values. The sensory appearance, shape, color, hardness/softness, taste, smell, fragility, internal structure, chewiness and general acceptability scores of the pastries were detected in the ranges of 2.50-7.50, 2.30-7.70, 2.5-7.70, 2.30-8.40, 2.40-7.80, 4.30-7.30, 4.00-6.80, 3.40-7.60, 3.30-8.40 and 3.00-7.66, respectively. Considering the sensory properties of the samples, it was seen that the addition of 30% buckwheat flour was close to the control sample in terms of general acceptability. Considering the optimum chemical, physical, textural and sensory properties, it has been revealed that up to 50 % (g/g) Buckwheat flour can be used in the Fatayer formula.

Shear wave elastography of kidneys in children: utility in distinguishing steroid-resistant and steroid-sensitive nephrotic syndrome.

To assess the renal elasticity values using (SWE) and correlate the values with steroid sensitivity to distinguish between steroid-resistant nephrotic syndrome (SRNS) and steroid-sensitive nephrotic syndrome (SSNS) in children. In this IRB-approved cross-sectional study, 83 children (4-14years) diagnosed with nephrotic syndrome were included from July 2021 to December 2022. SWE measurements were done for each kidney's upper pole, interpolar region, and lower pole. Mean as well as median SWE were calculated. Correlation of the renal stiffness values was done with different laboratory findings (blood urea, serum creatinine, 24h urine protein, serum albumin, and serum cholesterol), the grayscale findings (cortical echogenicity, and corticomedullary differentiation), and the final diagnosis of SRNS and SSNS. The statistical tests were done at a significance level of α = 0.05. The median (IQR) overall SWE of kidneys was higher in SRNS group 12.64 (8.4-19.68) kPa than SSNS group 9.87 (8.20-12.56) kPa. The difference was significant (p = 0.004). At a cut-off of ≥ 10.694kPa (AUROC- 0.641), the overall SWE predicted SRNS group with a sensitivity of 70% and a specificity of 63%. A significant correlation (p < 0.05) was found between the SWE and 24-h urine protein, cortical echogenicity, and corticomedullary differentiation in SSNS, while only between SWE and corticomedullary differentiation in SRNS. The mean SWE was higher in children with SRNS. While SWE has potential to differentiate SSNS from SRNS, a different study design where SWE is performed at presentation is needed for confirmation.

ANALYSIS OF THE DYNAMICS OF LABOR ABSORPTION IN WEST SUMATRA PROVINCE IN 2018-2020

The study aims to analyze the situation of employment in West Sumatra Province using indicators such as the employment status, sector/business field, and type of work, labor productivity, and labor elasticity during the period 2018-2020. The descriptive quantitative approach was employed, using secondary data from Badan Pusat Statistik (BPS). The data used include the main job status, economic sector, type of work, and constant price GRDP. The statistical data obtained describe the characteristics of the employment situation in the Province of West Sumatra. Information on the results of data analysis is visualized in the form of tables, graphs, and descriptions. Calculations are carried out to determine the value of labor productivity and elasticity. This method is carried out by calculating the ratio between the growth of employment opportunities and the growth of GRDP from different time points. The results of this study indicate that employment status in West Sumatra is dominated by formal workers. The primary and tertiary business sectors absorb more labor than the secondary sector. The agricultural, forestry, hunting, and fishery business workers are very dominant in absorbing labor in West Sumatra Province in 2018-2020. Total labor productivity decreased in 2020 due to a decrease in regional income in several sectors/business fields during the Covid-19 pandemic. Labor elasticity by sector/business field in West Sumatra mostly has a value of less than zero with the water supply, waste management, waste, and recycling sectors having the highest labor elasticity values.

EFFECT OF MATERIAL, ADHESIVE AND LOADING ON THE STIFFNESS OF WOODEN DOWEL JOINTS

The objective of this study was to evaluate the effects of selected parameters, such as type of loading (compression and tension), the wooden dowel species, and the adhesives type on the joint stiffness. Beech, oak, and Scots pine woods were used as wooden dowel material, and polyvinylacetate (PVAc) and polyurethane (PUR) adhesives were used as adhesive agents. Elastic stiffness on diagonal tension and compression tests were applied on 120 pieces of test samples prepared. The results showed that there was found out that the highest average elastic stiffness value of 656 Nm/rad was achieved in the oak dowel joints bonded with PVAc adhesive under compression loading. The lowest average value of 293 Nm/rad was found in the Scots pine dowel joints subjected to compression stress using PUR adhesive. On average, the elastic stiffness of the oak dowel joints bonded with PVAc adhesive was 17% higher than the elastic stiffness of the Scots pine dowel joints bonded with PUR adhesive. The influence of the wooden dowel species and the adhesive type were found statistically significant.

Determining the effective elastic thickness through cross-correlation between isostatic disturbances

The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed the vertical flexure value of the crust for a specific elastic thickness using a given topographic dataset. The gravity disturbance due to the topography was determined after the calculation. A grid of values for the elastic thickness parameter was generated. Then, a moving correlation was performed between the observed gravity data (representing actual surface data) and the calculated data from the forward modeling. The optimum elastic thickness of the particular point corresponded to the highest correlation coefficient. The methodology was tested on synthetic data and showed that the synthetic depth closely matched the original depth, including the elastic thickness value. To validate the results, the described procedure was applied to a real dataset from the Barreirinhas Basin, situated in the northeastern region of Brazil. The results show that the obtained crustal depth is highly correlated with the depth from known models. Additionally, we noted that the elastic thickness behaves as expected, decreasing from the continent towards the ocean. Based on the results, this method has the potential to be employed as a direct estimate of crustal depth and elastic thickness for any region.

Influence of temperature on the elastic properties of graphene and graphene-like nanosheets based on the asymptotic homogenization method

In this paper, the effective elastic properties of hexagonal monolayers such as graphene, boron nitride, silicon carbide, and aluminum nitride are evaluated using the asymptotic homogenization method taking into account temperature changes. The effective properties are determined analytically by considering temperature, force constants, bond lengths, and thickness, using atomic interactions within the context of the unit cell problem. The relationship between environmental temperature and the coefficient of thermal expansion is established by considering changes in the values ​​of bond stretching, bond angle bending, and torsion resistance constants at different temperatures from 0 to 1800 K. The results provided by the proposed homogeneous model are consistent with the valid findings of other researchers in the literature. It is found that these different hexagonal nanosheets exhibit isotropic temperature-dependent properties and their Young's and shear modulus decrease almost linearly as the temperature rises, considering a constant coefficient of thermal expansion. However, Poisson's ratio is found to be independent of temperature. Furthermore, the temperature-dependent elastic properties of these nanosheets become nonlinear when the variation of the coefficient of thermal expansion with temperature is taken into account. The Young and shear moduli of the nanosheets increase as the coefficient of thermal expansion decreases and vice versa. The highest elastic modulus values are obtained when the thermal expansion is close to its minimum threshold. However, it is recognized that the elastic modulus of graphene and boron nitride nanosheets is higher than that of silicon carbide and aluminum nitride at any temperature. As an alternative to lengthy computer modeling or rigorous testing, the homogeneous models provided can be used to simulate nanosheets.

Numerical investigation of the effective mechanical properties of Octet Truss lattice structures with different strut geometry

Lattice structures have an important role in lightweight structure applications as they can supply their mechanical performance with less material. Porous structures designed with inspiration from nature, has been used in many industries such as aerospace, automotive, defense industry and biomedical field. In order to continue these advances, studies on various design configurations of porous structure geometries are carried out. This study aimed to increase the usage potential of Octet Truss lattice structures in various sectors. A numerical model is created for 3 variable parameters: strut geometry, porosity, and material type. The effective elastic modulus values are determined based on the principles of Hooke's law for each model. Based on the obtained effective elastic modulus values, it has been concluded that differences in strut geometries, porosities, and material types contribute to 1.27%, 68.85%, and 29.86% of the observed effects, respectively. In order to establish a correlation between these factors, the data is transmitted to the MATLAB software, where equations are generated using the curve fitting approach. A total of nine equations have been generated and the R-square for these equations above 0.99. According to the two desired constant values, the effective elastic modulus can be calculated using these equations without any restrictions.

The anticancer impacts of free and liposomal caffeic acid phenethyl ester (CAPE) on melanoma cell line (A375).

The deadliest type of skin cancer, malignant melanoma, is also the reason for the majority of skin cancer-related deaths. The objective of this article was to investigate the efficiency of free caffeic acid phenethyl ester (CAPE) and liposomal CAPE in inducing apoptosis in melanoma cells (A375) in in vitro. CAPE was loaded into liposomes made up of hydrogenated soybean phosphatidylcholine, cholesterol, and 1,2-distearoyl-sn-glycero-3 phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000],and their physicochemical properties were assessed. (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test was performed for comparing the cytotoxicity of free CAPE and liposomal CAPE at dosages of 10, 15, 25, 50, 75 and the highest dose of 100 μg/mL for period of 24 and 48 h on A375 cell line to calculate IC50. Apoptosis and necrosis were evaluated in A375 melanoma cancer cells using flow cytometry. Atomic force microscopywas utilized to determine the nanomechanical attributes of the membrane structure of A375 cells. To determine whether there were any effects on apoptosis, the expression of PI3K/AKT1 and BAX/BCL2 genes was analyzed using the real-time polymerase chain reaction technique. According to our results, the maximum amount of drug release from nanoliposomes was determined to be 91% and the encapsulation efficiency of CAPE in liposomes was 85.24%. Also, the release of free CAPE was assessed to be 97%. Compared with liposomal CAPE, free CAPE showed a greater effect on reducing the cancer cell survival after 24 and 48 h. Therefore, IC50 values of A375 cells treated with free and liposomal CAPE were calculated as 47.34 and 63.39 μg/mL for 24 h. After 48 h of incubation of A375 cells with free and liposomal CAPE, IC50 values were determined as 30.55 and 44.83 μg/mL, respectively. The flow cytometry analysis revealed that the apoptosis induced in A375 cancer cells was greater when treated with free CAPE than when treated with liposomal CAPE. The highest nanomechanical changes in the amount of cell adhesion forces, and elastic modulus value were seen in free CAPE. Subsequently, the greatest decrease in PI3K/AKT1 gene expression ratio occurred in free CAPE.

Synthesis of thermoset elastomer from microbial oil derived from the fermentation of sugarcane

AbstractIn the context of the 21st century, the integration of diverse perspectives within the circular economy framework, encompassing waste management, economic growth, and environmental sustainability, stands out as a paramount challenge. Addressing this challenge, an innovative avenue emerges through the application of microbial oil to replace traditional petroleum in the synthesis of essential commodity chemicals. This groundbreaking study takes a significant step toward this goal by introducing a pioneering polyester material boasting an exceptionally high renewable content. This material is synthesized through melt polycondensation, utilizing a novel primary feedstock derived from the oily residue extracted post‐distillation of β‐farnesene (FDR). The ingenious approach involves fermenting sugarcane syrup using a genetically engineered yeast strain of Saccharomyces cerevisiae. The outcome of this study reveals the creation of an amorphous polymer with rubber‐like attributes. These attributes include a Young's modulus of 3.9 MPa, with a maximum elastic strain and tensile stress values of 185.4% and 510 KPa, respectively, along with distinctive strain‐hardening characteristics. Remarkably, this material also exhibits indications of shape memory behavior in a temperature range spanning from −47 to 12°C, as discerned from dynamic mechanical analysis. Evidently, this novel polymer demonstrates exceptional promise in the realm of low‐temperature applications. Its intrinsic ability to uphold mechanical integrity, even when subjected to substantial deformations within its service conditions, positions it as an invaluable resource for various components requiring resilience in challenging environments.

Resonance, Velocity, Dispersion, and Attenuation of Ultrasound-Induced Shear Wave Propagation in Blood Clot In Vitro Models.

Improve the characterization of mechanical properties of blood clots. Parameters derived from shear wave (SW) velocity and SW amplitude spectra were determined for gel phantoms and in vitro blood clots. Homogeneous phantoms and phantoms with gel or blood clot inclusions of different diameters and mechanical properties were analyzed. SW amplitude spectra were used to observe resonant peaks. Parameters derived from those resonant peaks were related to mimicked blood clot properties. Three regions of interest were tested to analyze where resonances occurred the most. For blood experiments, 20 samples from different pigs were analyzed over time during a 110-minute coagulation period using the Young modulus, SW frequency dispersion, and SW attenuation. The mechanical resonance was manifested by an increase in the number of SW spectral peaks as the inclusion diameter was reduced (P < .001). In blood clot inclusions, the Young modulus increased over time during coagulation (P < .001). Descriptive spectral parameters (frequency peak, bandwidth, and distance between resonant peaks) were linearly correlated with clot elasticity values (P < .001) with R2 = .77 for the frequency peak, .60 for the bandwidth, and .48 for the distance between peaks. The SW dispersion and SW attenuation reflecting the viscous behavior of blood clots decreased over time (P < .001), mainly in the early stage of coagulation (first minutes). The confined soft inclusion configuration favored SW mechanical resonances potentially challenging the computation of spectral-based parameters, such as the SW attenuation. The impact of resonances can be reduced by properly selecting the region of interest for data analysis.

Closed-form approach for the elastic critical moment of I-girders with corrugated web

Using corrugated web girders offers several advantages, including increased resistance to lateral-torsional buckling. Researchers have proposed various methods for determining the critical moment value as a function of the cross-sectional geometry. Previous studies have suggested that the enhanced critical moment is attributable to a larger warping constant. In this paper, we present the results of a systematic numerical study using finite element analysis on girders with various corrugated web shapes. Bending along the weak axis demonstrates that corrugated web girders possess a higher moment of inertia. Furthermore, our torsion linear analysis indicates that the increase in the critical moment is primarily due to a larger torsional constant. We compare the elastic critical moment values obtained using finite element linear buckling analysis to those derived from theoretical expressions that introduce equivalent section properties. Our results illustrate that the equivalent section properties method provides values that closely resemble those obtained using finite elements. Finally, we provide closed-form expressions that can be used to estimate equivalent section properties for any girder with a corrugated web. Our findings suggest that employing these expressions to calculate the critical moment yields results that are satisfactory when compared to those obtained through finite element linear buckling analysis.

IMPROVEMENT OF THE NON-DESTRUCTIVE METHOD FOR DETERMINING THE MECHANICAL CHARACTERISTICS OF ELEMENTS OF MULTILAYER STRUCTURES ON THE EXAMPLE OF PAVEMENTS

The article is devoted to solving the urgent problem of improving the method of nondestructive testing of the condition of non-rigid road clothes. In addition to the previously developed approach to determining the mechanical parameters of materials of structural layers of nonrigid road coverings based on solving the inverse coefficient problem of restoring operational elastic modules providing specified displacement fields, an approach was developed that allows determining the parameters of energy dissipation in the structure of multilayer road pavement based on the correction of dynamic hysteresis loops recorded in the field and calculated using mathematical model of dynamic VAT. The article presents the results of numerical simulation of dynamic hysteresis loops for two different variants of multilayer structures. The possibilities of correcting the shape of hysteresis loops and their area by varying the tangents of the energy loss angles in layers of a multilayer medium and the elastic modulus of a homogeneous half-space are shown. The complex correction of the elastic modulus values of the structural layers of road clothes and the calculated loops of dynamic hysteresis made it possible to fully take into account the processes of energy attenuation at a distance from the point of application of the load. During the correction, it was found that the values of the elastic modulus of the road layers and the tangents of the loss angles in them have a complex effect on the areas of dynamic hysteresis loops and the nature of energy attenuation at a distance from the point of application of the load. At the same time, the elastic modulus of the underlying half-space is not limited in thickness to the greatest extent on the area of dynamic hysteresis loops (which led to an increase in the elastic modulus of the underlying half-space from 120 and 150 MPa for road construction variants with a reinforced and non-reinforced base to 170 and 160 MPa, respectively), and a decrease in the dissipated energy at a distance from the point of application This is primarily due to the tangent of the angle of energy loss in the half-space. The obtained values of the tangents of the loss angles are obviously related to the patterns of energy dissipation at the boundaries of the contacting layers of the pavement, and also take into account all possible anomalies and delaminations in the calculated structures. Within the framework of this article, calculated hysteresis loops on the surface of the pavement were obtained for the first time, the deformation energy was calculated based on their areas, and the possibility of their comparison with those registered experimentally was proved.

A Laboratory Trial on the Usability of Waste Impregnated Papers in Standard Quality High Density Fiberboard (HDF) Production

The aim of this study is that determination of the usability of the different types of waste impregnated papers (IP) in a standard HDF production line. For this purpose, the HDF panels were produced from industrial prepared fibers and waste of IP, called decor and overlay, preparation lines by three different ratios (from 5% to 15%). Some important properties of HDF’s were determined according to standard test methods and were evaluated by statistical analysis in a 95% confidence interval. According to the evaluation results, it was concluded that it is possible to statistically evaluate the use of overlay and decor papers up to 15% in a standard production in terms of density, and equilibrium moisture, thickness swelling (2 h and 24 h), and modulus of rupture values. In addition, it was observed that the modulus of elasticity and tensile strength values generally improved as the amount of waste paper increased, regardless of the type of waste paper. However, the significant increase in formaldehyde emission showed that evaluating these waste papers without changing in the standard production line is difficult.

Enhanced Reverse-Engineering Method for Accurately Predicting Lamina Properties in Laminated Composites via Combined Static and Dynamic Finite Element Simulations

This study aims to ascertain the material characteristics that are intrinsic to the prepreg layer within a laminated composite structure. The elastic modulus of the lamina, a primary determinant of composite structural behavior, is the focal point of this analysis. This parameter has been assessed by employing reverse-engineering techniques on a composite composed of sequentially stacked prepregs. The investigation entailed simulating the behavior of the composite under static loads and conducting modal analyses to reflect both static and dynamic conditions. The findings indicate that the elastic modulus values derived from combined tensile and modal analysis simulations exhibit superior accuracy compared to those obtained through tensile simulation alone. Specifically, the maximum prediction error for E1 (the tensile-direction elastic modulus of one lamina sheet) decreased from 1.17% to 0.28%, and that of E2 (the transverse-direction elastic modulus of one lamina sheet) decreased from 12.01% to 7.30%. Further simulations incorporating fabrication error variances underscored the critical nature of precise E2 analysis. The proposed methodology evidenced a more accurate assessment of E2, underscoring its potential to enhance the reverse-engineering process in composite material design.

Between-sexes differences in lumbopelvic muscle mechanical properties of non-climacteric adults: a cross-sectional design

The lumbopelvic muscle mechanical properties (MMPs) are clinically relevant, but their dependence on sex remains unknown. Therefore, this study aimed to identify if lumbopelvic MMPs depend on the sex in a young adult population. Thirty-five healthy nulliparous women and 35 healthy men were analyzed (age range: 18–50). Lumbopelvic MMPs, that is, tone, stiffness, elasticity, relaxation and creep, assessed with MyotonPRO®, and pelvic floor (PF) health questionnaires were compared between-sexes. Intra-group correlations between sociodemographic and clinical data, and MMPs were also determined. The MMPs of PF were different between healthy non-climacteric adults of both sexes, with women showing higher values of tone and stiffness and lower values of elasticity and viscoelastic properties than men (in all cases, p < 0.03). At lumbar level, tone and stiffness were higher for men at both sides (in all cases, p < 0.04), and relaxation was lower at left side (p = 0.02). The MMPs showed few correlations with sociodemographic data within women. However, within males, there were positive correlations for PF stiffness and viscoelastic parameters with age, BMI and function (0.334 < r < 0.591) and, at lumbar level, negative correlations for tone and stiffness ( − 0.385 < r < −0.590) and positive correlations for viscoelastic properties (0.564 < r < 0.719), with BMI. This indicated that between-sexes differences of lumbopelvic MMPs depend on the specific location of assessment in healthy non-obese young individuals. Women show higher tone and stiffness and lower elasticity and viscoelasticity than men, at PF level.