Mixture Parameters Research Articles

Investigation of the structure of pasta

This article discusses the structure of the properties of oilseed cakes in the production of pasta. During the research, a partial replacement of premium wheat with pumpkin, soy, peanut, sunflower and linseed cake was made. The incorporation of pumpkin, soy, peanut, sunflower, and flax cakes stems from the rich variety of vitamins present in these raw materials. As part of the study, the amino acid composition of the studied cakes, the rheological and physico-chemical parameters of pasta mixtures were considered. The results obtained comply with the requirements established in the standardization documents and technical regulations of the Eurasian Economic Union. Studies have shown that the addition of oilseed cakes does not reduce the rheological and technological parameters of pasta. Quality indicators are determined in accordance with TR CU 021/2011 "On food safety", TR CU 022/2011 "Food products in terms of their labeling", TR CU 029/2012 "Safety requirements for food additives, flavorings and technological aids", regulatory and technical documents GOST 31743-2017 "Pasta products. General technical conditions", GOST 31964-2012 "Pasta products. Acceptance rules and methods for determining quality", GOST 8057-95 "Soybean meal. Technical conditions", GOST 11201-65 "Peanut cake food. Technical specifications, GOST 80-96 "Sunflower cake. Technical specifications, GOST 10974-95 "Flax cake. Technical conditions".

О влиянии топливного биоэтанола на эксплуатационные свойства транспортных двигателей

Purpose: To comprehensively consider the effect of bioethanol as an additive to gasoline on the operational properties of transport engines from the point of view of their differences in physical and chemical properties and technologies, taking into account not only advantages, but also disadvantages. To more profoundly evaluate the volatility of gasoline-ethanol mixtures at different ethanol and water contents, and its effect on startability. Methods: Comparison of available data in normative and reference literature, also in scientific publications. Conducting an experiment using the standard method for gasoline to measure the saturated vapor pressure of gasoline-ethanol mixture of various composition. Results: From the collected data, parameters of the gasoline-ethanol mixture that are important for operation of transport engines have been identified. The need for a detailed assessment of the influence of the composition of such mixtures on the structural materials of transport engines has been identified. Data have been obtained on the volatility of mixtures in a wide temperature range, simulating real operating conditions. No significant deterioration in startability has been revealed. A visible violation of the phase stability of mixtures containing more than 7.5% water has been noted. Practical significance: The measured degree of volatility and startability of gasoline-ethanol mixtures of the various composition allows us to conclude that their level in comparison with gasoline, for mixtures with a 5% ethanol content is satisfactory, and for mixtures with 85% ethanol, is relatively satisfactory. For the first time, the parameters of the provided standard procedure are expanded, relative to the usual temperature recommended when measuring the vapor pressure, to possibly wider limits, allowing a more complete picture to be obtained.

Efficient benchtop acid digestion of organic-rich sediments for ICP-MS analyses: testing analytical procedures on NIST 2702 standard reference material

Trace element abundances in organic-rich sediments are widely used in various fields of the geosciences, yet few contributions discuss the effectiveness of low-cost benchtop acid digestion techniques for such samples. Here, we tested three different sample preparation methods (acid digestion in closed and open vessels, and fusion) on twelve powder aliquots of organic-rich sediment, standard reference material NIST 2702. Comparison of newly obtained ICP-MS and LA-ICP-MS results with their respective certificate values, facilitates the assessment of digestion efficiency and the effects of vessel size, acid mixture, and other parameters on the recoveries of 29 trace elements. Our results show that benchtop digestion of organic-rich sediment in closed 7 mL PFA vessels using HF+HNO3+HClO4 mixture is more efficient compared with open vessel digestion treated with the same acid mixture (± HCl), with closed or open vessel digestions without HClO4, and with LA-ICP-MS measurements on fused glass discs.

Extractive distillation of tetrahydrofuran–ethanol azeotropic mixture with ionic liquid as extractant

AbstractBACKGROUNDThe tetrahydrofuran–ethanol azeotrope cannot be separated by common distillation, but can be effectively separated by extractive distillation. Extractive distillation can be simulated by Aspen Plus software. The minimum annual cost of the process can be calculated to assess ionic liquid separation ability. The interaction energy can be used to explain the separation mechanism.RESULTSThe non‐random two‐liquid model parameters of ternary mixtures for tetrahydrofuran and ethanol containing tributylmethylammonium acetate or 1‐octyl‐3‐methylimidazolium acetate were obtained. Thermodynamic property databases of tributylmethylammonium acetate, 1‐hexyl‐2,3‐dimethylimidazolium acetate and 1‐octyl‐3‐methylimidazolium acetate were established. Based on the thermodynamic model parameters and properties, the sequential iterative method was used to determine the best operating conditions and minimum total annual cost the of extractive distillation process. The interaction energy was calculated to explain the separation mechanism.CONCLUSIONSThe separation performance of tributylmethylammonium acetate is better than that of 1‐hexyl‐2,3‐dimethylimidazolium acetate or 1‐octyl‐3‐methylimidazolium acetate. The selection and design of the ionic liquids can be conducted in terms of the interaction energy. © 2023 Society of Chemical Industry (SCI).

A Study on the Genetic Algorithm Optimization of an Asphalt Mixture’s Viscoelastic Parameters Based on a Wheel Tracking Test

The generalized Maxwell (GM) constitutive model has been widely applied to characterize the viscoelastic properties of asphalt mixtures. The parameters (Prony series) of the GM are usually obtained via interconversion between a dynamic modulus and relaxation modulus, and they are then input to a finite element model (FEM) as viscoelastic parameters. However, the dynamic modulus obtained with the common loading mode only provides the compressive and tensile properties of materials. Whether the compression or tensile modulus can represent the shear properties of materials related to flow rutting is still open to discussion. Therefore, this study introduced a novel method that integrates the Kriging model into the genetic algorithm as a surrogate model to determine the viscoelastic parameters of an asphalt mixture in rutting research. Firstly, a wheel tracking test (WTT) for AC-13 was conducted to clarify the flow rutting development mechanism. Secondly, two sets of the AC-13 viscoelastic parameters obtained through the optimization method and the dynamic modulus were used as inputs into the FEM simulation of the WTT to compare the simulation results. Finally, a sensitivity analysis of viscoelastic parameters was performed to improve the efficiency of parameter optimization. The results indicating the viscoelastic parameters obtained by this method could precisely characterize the development law of flow rutting in asphalt mixtures.

BILFF: All-Atom Force Field for Modeling Triazolium- and Benzoate-Based Ionic Liquids.

We present an extension of our previously developed all-atom force field BILFF (Bio-polymers in Ionic Liquids Force Field) to three different ionic liquids: 1-ethyl-3-methyl-1,2,3-triazolium acetate ([EMTr][OAc]), 1-ethyl-3-methyl-1,2,3-triazolium benzoate ([EMTr][OBz]), and 1-ethyl-3-methylimidazolium benzoate ([EMIm][OBz]). These ionic liquids are of practical importance as they have the ability to dissolve significant amounts of cellulose even at room temperature. Our force field is optimized to accurately reproduce the strong hydrogen bonding in the system with nearly quantum chemical accuracy. A very good agreement between the microstructure of the quantum chemical simulations over a wide temperature range and experimental density data with the results of BILFF were observed. Non-trivial effects, such as the solvation shell structure and π-π stacking of the cations, are also accurately reproduced. Our force field enables accurate simulations of larger systems, such as solvated cellulose in different (aqueous) ionic liquids, and is the first to present the optimized parameters for mixtures of these solvents and water.

Prediction of mixture pelleting based on compression parameters

Despite pelleting being a widely used powder continuous densification process, most fundamental studies of powder pelleting have focused on single-component systems. There is thus an obvious need for an improved understanding of the pelleting behavior of mixtures. In this study, the Kawakita parameter and Heckel parameter for multi-component mixtures were derived based on the assumption of ideal mixing behavior. A prediction model for the pelleting performance of multi-component mixed powders was proposed based on these powder compression parameters. Single pelleting (SP) experiments were conducted on mixtures of different edible powders and weight proportions to validate the model. The predicted and measured values of the Kawakita parameter and Heckel parameter were generally in good agreement, indicating that the assumption of ideal mixing behavior is valid for this type of system. Moreover, the consistency between the predicted pressure and the measured pressure of SP indicates that the prediction models for the pelleting of mixtures can effectively predict the pelleting ability of the mixture.

Evaluation of the impact of various stabilizing additives, including hydrolysis lignin, on the basic physical and operational parameters of rubble-mastic asphalt concrete mixtures

The paper considers the use of various stabilizing additives, including hydrolysis lignin, in rubble-mastic asphalt mixtures. Laboratory tests were conducted using calibrated measuring instruments and certified laboratory equipment, along with officially recognized methods for testing the physical and mechanical properties of asphalt mixtures. Based on the data obtained, a comparative analysis of the effect of stabilizing additives on the main physical and operational indicators of rubblemastic asphalt concrete mixtures was carried out. It was established that the use of different stabilizing additives in rubble-mastic asphalt concrete mixtures did not lead to significant changes in the basic physical and operational indicators, except for the binder flowing indicator, i.e., the ability of rubblemastic asphalt concrete mixtures to retain bitumen. The laboratory studies also confirmed the possibility of using a stabilizing additive – hydrolysis lignin – without compromising the physical and operational characteristics of the mixture according to GOST R 58406.1-2020. A slight increase in water resistance was observed when hydrolysis lignin was added, largely due to its ability to modify road bitumen and its high content in the mixture compared to other additives.

Study of the influence of vitamins on the fermentation process in the production of yogurt

The development of the technology of vitaminized dairy products remains a relevant topic for research, because dairy products are included in the daily diet of both children and adults, so the use of such products can reduce the number of cases of hypovitaminosis, both seasonal and general. The purpose of the study is to investigate the effect of introduced ready-made vitaminized complexes on the fermentation process of milk mixtures during the production of yogurt. The article presents the results of studies conducted to determine the effect of vitamins A, D, E, C on the fermentation process of milk mixtures during the production of yogurt, which were added to the milk mixture in order to increase the biological value of the finished product. Fermentation is an important stage in the production of yogurt. To study the influence of added preparations of vitamins A, D, E, C on the fermentation process during the production of yogurt, 2 samples were chosen: “control” – a milk mixture for yogurt pasteurized at 90...92 °C without aging with the addition 5 % sugar. The “experimental” sample is a milk mixture for yogurt with the addition of 5 % sugar, pasteurized at 90...92 °C without aging, with the addition of vitamin preparations. Fermentation processes are influenced by the composition and dose of primary inoculation of sourdough cultures, physicochemical parameters of raw milk, additives included in the normalized mixture, as well as technological process parameters. Vitamins added to the milk mixture during the production of yogurt can affect the fermentation process of the milk mixture and the quality indicators of the finished product during storage. Thus, the task arose to investigate the effect of added preparations of vitamins A, D, E, C on the fermentation process, and to substantiate the fermentation regimes for the production of vitaminized yogurt. As a result of the conducted research, it was determined that vitamin preparations added to the milk mixture before heat treatment did not significantly affect the intensity of acid formation and gel formation. There is also no influence on the development of lactic acid microorganisms that were part of the sourdough, which is confirmed by the results of microbiological studies of the finished product. So, the fermentation parameters of milk mixtures for the production of fortified yogurt are as follows: temperature – (40 ± 2) °C, duration of fermentation – 5.5...6 hours. It has been established that the introduction of a vitaminized complex (A, D, E, C) into the yogurt recipe does not require significant changes in the technological process and equipment line. The content of viable lactic acid bacteria in the developed product is 4.0 ± 0.5 107 CFU/g, and there are no Coliforms, which meets regulatory requirements.

Sensitivity and Reliability Analysis of Ultrasonic Pulse Parameters in Evaluating the Laboratory Properties of Asphalt Mixtures.

The ultrasonic test is a promising non-destructive testing technique for evaluating the properties of asphalt mixtures. To investigate the applicability and reliability of ultrasonic testing technology (UTT) in evaluating the performance of asphalt mixtures, ultrasonic tests, indirect tensile tests, compression tests, and dynamic modulus tests were carried out at various temperatures. Subsequently, the distribution characteristics of ultrasonic traveling parameters for asphalt mixtures were analyzed. The variation of ultrasonic pulse velocity and amplitude in dry and wet states with temperature was studied. Then, the correlation between the ultrasonic parameters and both the volume parameters and the mechanical performance parameters of asphalt mixtures was revealed, and the functional relationship between ultrasonic pulse velocity and compressive strength was established. Finally, the reliability of predicting high-frequency dynamic modulus by ultrasonic velocity was verified. The laboratory tests and analysis results indicate that both ultrasonic pulse velocity and amplitude in dry and wet conditions show a decreasing trend with an increase in temperature. Ultrasonic parameters are greatly influenced by asphalt content and mineral aggregate content of 9.5~13.2 mm and 13.2~16 mm. The dynamic modulus at a high-frequency load can be predicted by using ultrasonic velocity, and predicting the results for OGFC and SMA mixtures deduced by using the UPV at a high-frequency load have higher reliability.

Characteristic identification of steel corrosion products based on terahertz transmission spectroscopy

Corrosion of steel materials (such as rebars and steel plates) usually occurs under coating materials. It is, with the existing non-destructive testing (NDT) technologies, difficult to accurately determine the corrosion of steel materials. The terahertz (THz) electromagnetic waves can penetrate the non-polar materials, and theoretically experience an absorption resonance with some corrosion products crystals (i.e., iron oxides). The THz spectroscopy has, therefore, a great application potential to characteristically identify the corrosion of steel materials. In the present study, the optical parameters and, especially, the positions of the characteristic absorption peaks of the corrosion products were systematically investigated and identified using the THz system. The experimental results showed that the refractive index of the different corrosion product samples was in the range of 2.7–3.4 in the effective frequency range of 0 THz - 1.2 THz, and the content of Fe3O4 had a large influence on the optical parameters in the corrosion product mixtures. To measure the characteristic absorption peaks of the corrosion products, the effective frequency range was extended to 0 THz - 10 THz by an assembled broadband THz system. Within this range, the positions of the characteristic absorption peaks were identified as 3.4 THz, 4.2 THz, 4.85 THz, and 5.8 THz for Fe2O3, and as 3.6 THz, 4.05 THz, 5 THz, and 5.45 THz for α-FeOOH. For Fe2O3 and α-FeOOH, the intensities of the absorption peaks at 4.85 THz and 3.6 THz, respectively, showed a linear relationship with the mass content. Furthermore, the THz spectroscopy could accurately identify Fe2O3 and α-FeOOH in the corrosion product mixtures by comparing with the results from IR spectroscopy and Raman spectroscopy. This means that the occurrence of steel corrosion could be detected according to the characteristic absorption peaks of Fe2O3 and α-FeOOH. The experimental results provide a basis for the application of THz spectroscopy in the NDT of the corrosion of steel materials.

Vibration Investigation of Circular Graphene Sheet with Geometrical Defect Considering Two-Phase Local/Nonlocal Theory Exposed to the Magnetic Field

In this work, the mixed local/nonlocal elasticity theory is developed for the investigation of the vibration of a circular graphene sheet with a structural defect located in a magnetic field. When graphene is placed in a magnetic field, the Lorentz force is applied to it, which is calculated using Maxwell’s equations. The insufficiency of Eringen’s nonlocal theory (ENT) caused some authors to employ the two-phase theory (TPT) to study nanostructures. Geometric imperfections can happen in the manufacturing process of graphene sheets. Lots of these imperfections can be modeled as a hole. So, in this work, an imperfection is considered as the centric hole. Governing equations, in Newtonian formulation, are extracted in the integrodifferential form. The boundary conditions are selected as clamped at inner and outer edges. To discretize the equation of motion we employ Galerkin’s approach. The solution is validated using a comparison study between the presented results and those that exist in the literature, and the accuracy of the suggested approach is verified. The effectiveness of the mixture parameter, magnetic field, radius of imperfection, and nonlocal parameter is examined on the natural frequency. The results exhibit that an increase in the mixture parameter and magnetic field increases the natural frequency of the graphene sheet.

New weighted-sum-of-gray-gases radiation model for oxy-fuel combustion simulation of semi-coke from coal-based poly-generation

Poly-generation based on coal pyrolysis achieves the graded utilization of coal. Further using the produced semi-coke for oxy-fuel combustion could achieve CO2 capture. In this study, a new weighted-sum-of-gray-gases radiation model was developed specifically for the numerical calculation of semi-coke oxy-fuel combustion. The applicable path-length range of the new model was 0.001–60 m, and the temperature range was 500–2,500 K. This model could accurately calculate the radiation characteristic parameters of the gas mixture for the semi-coke combustion. The results of the one- and two- dimensional cases show that the model could accurately predict the radiative heat transfer of the gas mixture. The average error of the radiative heat flux did not exceed 6.72 % and the error of the radiation source term did not exceed 10.96 %, while the maximum error of the radiation source term can reach 62.62 % for other WSGG models. Besides, the three-dimensional designed furnace simulation results show that the difference between the prediction of the outlet temperature of the furnace by the new and traditional models reached 110 K corresponds to a maximum difference of 26 % in radiation heat transfer. Therefore, the new WSGG model for numerical simulation of semi-coke oxy-fuel combustion is significant.

The investigation of surface free energy components and moisture sensitivity damage of asphalt mixes modified with carbon black using the sessile drop method

Asphalt pavement is vulnerable to moisture damage when water infiltrates the asphalt-aggregate interface and weakens their bond. To prevent this problem, researchers have explored the use of additives to increase resistance against moisture damage. The moisture sensitivity of asphalt mixtures can be assessed by measuring their basic properties related to the mechanism of moisture damage. One effective approach to this is using the surface free energy method, which calculates bond energies between different materials’ surfaces and identifies the most appropriate combination of asphalt and aggregate. High cohesion or adhesion bonding is crucial for the proper performance of asphalt mixtures, such as moisture damage resistance. This study aimed to investigate the effect of carbon black additive on moisture damage resistance using surface free energy methods, comparing results with the Tensile Strength Ratio (TSR) test. Modified asphalts containing 4, 8, 12, and 16% carbon black were tested, with natural base asphalt as a control sample. The study used surface free energy theory to determine moisture sensitivity parameters of asphalt mixtures by obtaining surface free energy components of the raw materials and testing the ratio of tensile strength. Results showed that adding 8% carbon black to the asphalt mixture improved moisture sensitivity, and increasing additive content up to 16% reduced it but still provided better results than samples made with pure asphalt. The study concluded that the surface free energy method can determine the suitable combination of asphalt and aggregate materials for resistance against moisture damage.

Study on sound absorption characteristic of porous asphalt mixture based on macroscale and mesoscale analysis

To explore the sound absorption characteristics of porous asphalt mixture, the effects of macroscopic parameters of asphalt mixture on sound absorption coefficient (SAC) were studied by the sound absorption coefficient test, and the mesoscopic void structure was investigated by industrial computed tomography (CT) and three-dimensional (3D) reconstruction techniques. The results show that the SAC can be increased by increasing the porosity or thickness and reducing the NMAS. The increase of porosity and the decrease of pavement thickness can better absorb high frequency noise (above 1000 Hz). Through the grey correlation analysis, it can be seen that the SAC of porous asphalt mixture is most affected by the porosity. There is a strong linear relationship between the microscopic void characteristic of porous asphalt mixture and the peak and mean value of SAC.

Isotropic triaxial tests of equal strength concrete with different mix compositions

High intensity impact loading on a concrete structure induces three dimensional high intensity stresses, the analysis of which requires appropriate constitutive relationships describing the isotropic and deviatoric stress components. The isotropic component known as the hydrostatic relationship or the equation of state (EOS) is in the focus of this paper. The literature relates the EOS of concrete to its uniaxial compressive strength. This paper aims at refuting this relationship and validating the conjecture that the EOS depends on the concrete mixture. For that purpose, different concrete mixes of equal strength have been tested. The mixture parameters are the water content (with the same w/c ratio), the coarse aggregate content and the maximum aggregate size.Using a unique test setup, hydrostatic tests were carried out to extremely high pressures at the 1GPa level. The results clearly show the pronounced differences between EOS curves representing different mixtures having the same concrete strength, thus validating the above conjecture.As the EOS is sometimes derived from oedometric tests, the present investigation exploited oedometric tests results on exactly the same concrete mixtures and strength to compare the hydrostatic and oedometric resulted EOS curves. The comparisons show that for most cases the stress at a certain volumetric strain in the oedometric curves are somewhat lower than these in the hydrostatic EOS curves. However, for mixes with a large maximum aggregate size with a high aggregate content, the oedometric EOS merges with the hydrostatic EOS curves in the mid-to high pressure levels.Finally, statistical analysis using Analysis of Variance has been employed to identify the effect of different mixture parameters and their combination on the differences in the EOS.These new results enhance the insight on concrete behavior under triaxial high pressures and contribute to the development of a new generation of EOS curves.

Analysis of Novel Porosity-Water-to-Binder Index for Prediction of Strength, Stiffness and Durability for Cemented Soils.

The initial weight and volume relationships are crucial factors in determining the strength, stiffness, and durability of cement-stabilized soils. The porosity/binder ratio has been widely used as a control parameter for stabilized soil mixtures. However, this approach does not take into consideration the water content used during the stabilization process, which can impact the strength and durability of the final product. To address this issue, this paper introduces the porosity-water/binder relationship as a new parameter to predict the strength, stiffness (Go), and durability against wetting-drying cycles of artificially cemented soils. The strengths, Go, and accumulated losses of mass (ALM) of different stabilized soils were compared based on this new parameter, and the comprehensive results were analyzed to demonstrate its effectiveness. The findings indicate that the new parameter is a suitable design parameter for soil-lime, soil-cement, and geopolymerized soil mixtures. Furthermore, it was determined that the water content has no effect on the splitting tensile strength to compressive strength ratio. The results of this study offer valuable insights into the optimization of stabilized soils and the development of improved soil stabilization processes.

Ternary Mixed Micelle Hexadecyltrimethylammonium Bromide-Dodecyltrimethylammonium Bromide-Sodium Deoxycholate: Gibbs Free Energy of Mixing and Excess Gibbs Energy of Mixing.

Pharmaceutical, food, and cosmetic formulations often contain binary or ternary surfactant mixtures with synergistic interactions amongst micellar building blocks. Here, a ternary mixture of the surfactants hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and sodium deoxycholate is examined to see if the molar fractions of the surfactants in the ternary mixed micellar pseudophase are determined by the interaction coefficients between various pairs of the surfactants or by their propensity to self-associate. Critical micelle concentrations (CMC) of the analyzed ternary mixtures are determined experimentally (spectrofluorimetrically using pyrene as the probe molecule). Thermodynamic parameters of ternary mixtures are calculated from CMC values using the Regular Solution protocol. The tendency for monocomponent surfactants to self-associate (lower value of CMC) determines the molar fractions of surfactant in the mixed micelle if there is no issue with the packing of the micelle building units of the ternary mixed micelle. If a more hydrophobic surfactant is incorporated into the mixed micelle, the system (an aqueous solution of surfactants) is then the most thermodynamically stabilized.

Correlation analysis of the gradation design parameters and mechanical performance of semi-flexible pavement

Semi-flexible pavement (SFP) has been widely used for ant-rutting performance and resistance in heavy load conditions. The asphalt mixture skeleton was the central part in the complex-skeleton material system. However, few studies have been made on the connection of asphalt mixture skeleton composition and performance on semi-flexible pavement material. Therefore, the relationship between the skeleton gradation volumetric characteristic and mechanical properties of semi-flexible pavement material was investigated. Eight gradations with different coarse aggregate contents were constituted. The mechanical performances were conducted to establish the relationship between primary gradation performance. The result shows that the porosity of the asphalt matrix and Cantabro abrasion test are related to the composition of gradation. The tensile performance, shear characteristics, and compressive strength were affected by the voids filled asphalt (VFA), porosity, and fine aggregate to asphalt ratio (FB), respectively. The Burgers model accurately reflected the creep curves of the semi-flexible pavement material specimens. The creep modulus was related to the VFA, porosity, and effective asphalt content (Pbe). The gradation design parameters of open-gradation asphalt mixtures for semi-flexible pavement materials could be obtained based on the target performance. It is possible to reduce material testing times based on the correlation analysis effectively.

Exposure to parabens and semen quality in reproductive-aged men

BackgroundParabens are common preservatives in personal care products, cosmetics, and medical goods. In the past few years, animal studies showed the male reproductive toxicity associated with some parabens. Yet, epidemiological studies have generated inconsistent findings and research rarely has focused on the mixture effects of the parabens. We aimed to explore the associations between individual paraben exposure as well as the mixture and semen quality parameters. MethodsA total of 795 male partners from preconception couples were included in the study. Their urine samples were analyzed for the concentrations of six parabens, namely methyl paraben (MeP), ethyl paraben (EtP), propyl paraben (PrP), butyl paraben (BuP), benzyl paraben (BzP) and heptyl paraben (HeP). Multiple linear regression models and weighted quantile sum regression (WQS) models were utilized to assess the relationships between individual paraben exposure and paraben mixture with semen quality parameters, respectively. ResultsAfter adjusting for covariates, exposure to a paraben mixture was significantly associated with declining sperm concentration, total sperm count, and progressive motility, among which BuP was identified as the main contributor to sperm concentration and total sperm count while MeP to progressive motility. Results from multiple linear regression models were generally in line with the WQS analysis. ConclusionsOur results suggest negative associations between paraben mixture and sperm concentration, total sperm count, and sperm motility among reproductive-aged men.