Mechanical Index Research Articles

The method for the estimation of fracture toughness of thin-walled metallic tube considering the effect of crack orientation

Thin-walled metallic tubes are very susceptible to axial or circumferential cracks in harsh environments such as high temperature, high pressure, and severe corrosion, which seriously endangers the service safety of thin-walled tubes. Fracture toughness is an essential mechanical property index for evaluating the service safety of thin-walled metallic tubes, and its special thin-walled structure cannot be tested by using the specimens with standard configuration. In this work, based on the principle of energy density equivalence, the load–displacement and J-integral expressions of thin-walled metallic tubes with axial and circumferential cracks are proposed, and the fracture toughness test method of thin-walled metallic tubes with axial and circumferential cracks is established. Typical zircaloy cladding tubes were selected to complete the fracture test, and the influence of crack orientation on their fracture properties was investigated. The results show that the fracture toughness of circumferential cracks is lower than that of axial cracks, the circumferential cracks also face the risk of fracture failure, and the estimation of fracture properties of the cladding tubes with circumferential cracks cannot be simply replaced by axial cracks.

Mix optimization and mechanical properties evaluation of lime-fly ash-stabilized loess in various engineering applications

Determining a rational mix ratio for lime-fly ash-stabilized loess (LFSL) can achieve multiple benefits of economy, environmental protection, and engineering quality improvement. This research was designed to optimize the mix ratios of LFSL applied in the pavement structure, subgrade, slopes, and foundations by conducting the unconfined compressive strength (UCS) test, California bearing ratio (CBR) test, resilient moduli (MR) test, triaxial test and uniaxial consolidation test on LFSL and lime-stabilized loess (LSL). Combined with the initial consumption of lime (ICL) test result and relevant specifications, the optimized mix ratios are as follows: 2% lime + 11.82% fly ash and 2% lime + 3.95% fly ash can reach the strength requirement of road base and subbase, respectively; 2% lime + 3.84% fly ash in building foundations and subgrade and 2% lime + 3.55% fly ash in slopes can reach the equal improvement effect of the LSL with 8% lime content. Three-factor comprehensive models were established and fitted in well with the experimental results of the LFSL with 2% lime content. Moreover, the development of correlations between UCS and other mechanical indices offers a shortcut for engineering property estimation. Finally, based on the abundant literature on LSL, another approach to estimating engineering quality was proposed for the LFSL with 2% lime content, which enhances the universality and practicability of the estimation models further.

Mechanical Properties and Performance of Mixtures with the Same Volumetric Classification

This study investigates the variations in performance among mixtures that are designed for use with the same traffic classification and whether a single mixture class index–volumetrics relationship (IVR) can be applied to all mixtures within that classification. Three surface mixtures, which are intended to serve traffic levels of 3–30 million equivalent single axle loads, were sourced from different regions in North Carolina: the coast; Piedmont; and the mountains. Dynamic modulus, cyclic fatigue, and stress sweep rutting tests were conducted using the asphalt mixture performance tester. Pavement performance simulations were performed using AASHTOWare Pavement ME Design for fatigue cracking predictions and FlexPAVE™ for permanent deformation predictions. The findings indicate substantial differences in mechanical properties, performance indices, and pavement performance among the mixtures despite having similar volumetric properties. The study also shows that an IVR calibrated for a mixture cannot be used to predict the performance of other mixtures within the same mixture classification as the tested mixture. This research highlights the need for restructuring the mixture classification system so that it is based on mixture performance rather than on volumetric design, with the ultimate goal being a performance-based or related specification to eliminate the limitations introduced by the use of volumetric properties.

Assessment of thermal and mechanical properties of fly ash based geopolymer blocks with a sustainability perspective using multi-criteria decision-making approach

Owing to the raising consciousness about the environment, geopolymers are slowly gaining the trust of researchers globally as the potential alternatives for the conventional building materials. Though, geopolymer emit far less CO2 than conventional building materials, the distance between the source and production site for a particular raw material can have significant impact on the environment. Thus, apart from meeting the mechanical and physical requirement of a building material, it must satisfy the sustainability requirement as well. Therefore, a combination of experimental and analytical method is adopted to select the optimal design mix to produce sustainable geopolymer block which fulfills the performance requirements as well. While compressive and flexural strength test were performed on the geopolymer block made using fly ash (FA) as the primary precursor and glass powder (GP) and steel slag (SS) as the partial replacement to ascertain its mechanical performance, physical performance was assessed by conducting tests like water absorption, bulk density, and thermal conductivity. The sustainability of geopolymer block is assessed by computing sustainability index based on embodied energy, global warming potential and global temperature potential. Multi-criteria decision making (MCDM) approach is then used to select the most optimal mix for geopolymer block production based on the mechanical, physical and sustainability index of each mix for geopolymer. A combination of FA-SS prepared with 14 M NaOH was found to be most sustainable based on the MDCM approach.

Comparative transcriptomic profile of two mandarin varieties during maturation reveals pectinase regulating peelability

Peelability is an important fruit quality trait of citrus. Pectinase is a group of heterozygous enzymes that function in pectin degradation, which is implicated in fruit ripening and softening. Previously we established a method to quantify citrus peelability through two mechanical indexes (peel-pulp adherence and peel resistance of penetration), and exhibited the genetic diversity of peelability in mandarins (Citrus reticulata Blanco). With this method, the present study first confirmed that Clementine is an easy-peeling mandarin in comparison with Fremont, and both showed increasingly easy peeling as the fruits matured. A range of measurements for the two mandarins at three maturation stages demonstrated that peelability had negative correlation with pectin contents but positive with pectinase activity. Subsequently, RNA sequencing was performed for comparative transcriptomic profiling of the two varieties at three maturation stages. We identified 12322 differentially expressed genes (DEGs) in total. Through comparative time-course analysis, the gene expression patterns were displayed with 12 clusters each in albedo and flavedo. Some cell wall-related gene ontology terms were over-represented in albedo and flavedo Cluster6. We mined 153 genes encoding pectinase (pectin methylesterase, polygalacturonase, pectin lyase (PL), beta-galactanase, pectin acetylesterase and alpha-arabinofuranosidase) in silica from Clementine genome, and 78 of them were significantly expressed in the peel of Clementine or Fremont, whereas 62/60 belonged to the DEGs in albedo/flavedo. In weighted correlation network analysis, six/five out of eight/nine modules in albedo/flavedo had eigengene values that were significantly correlated with the two mechanical indexes, pectin contents and pectinase activity, and six/eight pectinase genes were present in the co-expression networks. Based on the results of multi-approach bioinformatics analysis, three PL genes (Ciclev10004783m.g, Ciclev10020423m.g and Ciclev10031429m.g) were highlighted as potential regulators for peelability. This study provides clues for understanding the molecular basis of the regulation of citrus peelability, and proposes pectinase as a target for peelability-oriented breeding of citrus.

Study on Viscoelastic Poisson's Ratio of Nonwovens

Abstract Combined with Laplace transform and creep stress conditions, an accurate expression of the viscoelastic Poisson's ratio calculated from the transverse strain and relax modulus is derived. From creep and relax tests data, Prony series of the transverse strain and relax modulus of nonwovens with time were obtained, and the time-varying curve of the viscoelastic Poisson's ratio of nonwovens was simulated by 1stOpt software. The method proposed can effectively obtain the viscoelastic Poisson's ratio of nonwovens and provide a reference value for calculating mechanical indexes involved in its subsequent production and processing.

Micro-electro-mechanical acoustofluidic mixing system: A response surface-metaheuristic machine learning fusion framework

Micro-mixing is an essential step in various biological and chemical analyses and synthesis processes. In the present study, an acoustofluidic micromixer is designed, modeled, and its functionality has been investigated. Intelligent acoustofluidic is proposed as an evaluation-optimization method, based on Machine Learning algorithms. The first step involves designing a parametric geometry with multiple sharp edges. Following that, mathematical modeling of the system is carried out using Response Surface Methodology (RSM) and computational fluid dynamics (CFD). Geometrical parameters including the sharp edge tip angle and the channel thickness, along with the peak-to-peak actuation voltage were investigated. It was revealed that, due to the inherent nonlinearity of acoustic streaming, each design parameter could significantly impact the flow patterns and mixing performance of the acoustofluidic mixer. The mathematical surrogate model obtained from data-based modeling procedure is then employed for the artificial intelligence multi-objective optimization algorithms, i.e. Differential Evolution (DE) and Non-dominated Sorting Genetic Algorithm two (NSGA-II). The two objective functions are the mixing index and the mechanical energy consumption index (ME). The derived optimum solutions had low Mehcanical Energy (ME) values while yielding homogeneity in a wide range of applied voltages. This ensures the controllability of the proposed system, which is an invaluable feature in synthesis processes to determine the critical physical properties of the nanoparticles. Through the algorithm evaluation process, which was conducted to distinguish the more accurate and robust optimization method, it was revealed that the DE algorithm outperformed NSGA-II in generating optimum solutions with superior functionalities. In the final section, three optimum models, operating under three different Vp-p values, 10, 20, 30, were selected, and their acoustofluidic characteristics were analyzed. It was concluded that utilizing baffles with three sharp edges at low Vp-p values results in a 96% Mixing Index and 48% decrease in the power consumption of the system. However, at high Vp-p values, baffles with one sharp edge demonstrated superior mixing functionality, with a MI of 98%. Moreover, it is revealed that utilizing baffles with three-sharp edges results in an 80% increase of Mixing Index of the acoustofluidic micromixer.

Hysteretic behavior and cyclic constitutive model of corroded low-alloy steel in a corrosive environment

To quantitatively analyze the mechanical properties of corroded low-alloy steel under monotonic and cyclic loading, a cyclic constitutive model was established. Accelerated corrosion, monotonic tensile testing, and cyclic loading testing of 28 groups of Q345B steel specimens were conducted to examine how corrosion affected the monotonic tensile and hysteresis characteristics of the specimens, and the combined hardening parameters based on the Chaboche model were calibrated and confirmed based on the test findings. The results showed that corrosion clearly affected the monotonic stress-strain curve of steel and that most mechanical indices deteriorated linearly with respect to the corrosion rate. The combination of corrosion and cyclic cumulative damage exacerbated the degradation of the deformation capacity of the steel and affected its energy consumption capacity and cyclic hardening. The constitutive model of corroded steel calibrated on the basis of cyclic loading test data could effectively simulate the hysteresis performance of corroded Q345B steel under cyclic loading.

Experimental and numerical study of low-yield-point steel corrugated pipe dampers

The traditional isolation devices often encounter challenges such as uncontrolled deformation in the isolation layer, limited vertical tensile capacity, and environmental risks associated with the use of lead, a heavy metal. This study investigated an innovative low-yield-point steel damper called the corrugated pipe damper (CPD), which was introduced into a seismic isolation layer to overcome the limitations of conventional dampers. To investigate the behavior of the CPDs under cyclic loading, 10 specimens were designed and subjected to quasi-static cyclic loading and fatigue loading. The failure modes, hysteretic curves, stiffness degradation, and energy dissipation capacity of the specimens were obtained. Results indicated that the CPD exhibited good horizontal deformation and energy dissipation capacities, and excellent seismic fatigue performance. The horizontal force-displacement curves exhibited obvious yielding and strengthening phenomena, with the displacement increasing gradually, the bearing capacity increasing rapidly at the beginning, decreasing significantly after yielding, and increasing rapidly when the displacement was large. As the height increased or the average diameter decreased, the bearing capacity, horizontal stiffness, and hysteresis energy decreased, whereas the yield displacement increased. Finite element models were subsequently validated using experimental data and developed to simulate the horizontal cyclic behavior of the CPDs. Based on the finite element analysis, the connection construction and improvements for CPDs were analyzed and recommended while also revealing the relationships between the vertical additional force and horizontal displacement, and the prediction equations for some mechanical performance indexes of the CPD were proposed by detailed parametric analysis.

Quantitative time intensity curve analysis of contrast-enhanced ultrasound (CEUS) examinations for the assessment of focal liver lesions.

Contrast enhanced ultrasound (CEUS) is well-established for the characterization of focal liver lesions (FLLs). By using intravenous ultrasound contrast agents, followed by specific low mechanical index examinations, CEUS enables a high spatial and temporal resolution as well as a dynamic assessment of macro- and microvascularization down to the capillaries. Nevertheless, CEUS has the disadvantage of being examiner-dependent, so quantitative analysis of time-intensity curves in dynamic CEUS (D-CEUS) could provide further information. The aim of this article is to provide a general review of the current literature regarding the usefulness of D-CEUS in the assessment of FLLs.

Machine learning classification approaches to optimize ROP and TOB using drilling and geomechanical parameters in a carbonate reservoir

Drilling optimization has been broadly developed in terms of influential parameters. The assessment time and the effects of both geomechanical and drilling parameters were vital challenges of investigations. Drilling factors are applied force or rotation of drilling agents such as weight on bit (WOB), and geomechanical features represent mechanical indexes of rocks including unconfined compressive strength (UCS). Optimization efforts have been demonstrated on complex prediction methods whereas the simplicity of classification can offer some optimal ranges utilizing machine learning classifications in an accelerated process. In this study, a novel procedure using the supervised and semi-supervised learning approaches was conducted to classify and optimize the rate of penetration (ROP) and torque on bit (TOB). Firstly, in the case well, user-defined classes were assigned based on geomechanical units (GMU) and the ranges of high ROP and low TOB, thus classes divided drilling factors as GMUs of the case. Secondly, the feature selection was carried out by neural pattern recognition with three multi-objective optimization methods for classification. The inputs of classifications were WOB, hook load, pump pressure, flow rate, UCS, and internal friction angle. Classification approaches were decision trees, support vector machine (SVM), and ensemble learning. Finally, the bagged trees permutation and Laplacian SVM (LapSVM) algorithm separately revealed the significance of parameters and predicted the optimal ROP and TOB regions. Findings showed (1) in supervised classification of the case well, the cubic SVM and bagged trees had the highest area under the curve (AUC) and accuracy, on average 0.97 and 0.96, respectively. (2) The average accuracy of the supervised classifications in a test well was 91% except for the fine SVM, which makes them reliable for the fields with the least information. (3) The permutation outcomes for significant features, flow rate and UCS, exposed influential parameters for ROP and TOB optimization. (4) The semi-supervised method, LapSVM, not only acquired both ROP and TOB labels with an accuracy of 88% but also presented their optimal ranges in 95% of the assessed zones. (5) LapSVM deals with a limited training section perfectly opposed to the supervised version, which is vital for drilling investigation. (6) Implementing machine learning classification approaches with rock properties is a key factor in achieving effective drilling parameters in less time. More importantly, the recommended drilling factors concerning geomechanical properties can ameliorate both drilling performance and perception of upcoming collapse.

Prognostic value of left ventricular mechanical dyssynchrony indices derived from gated myocardial perfusion SPECT in coronary artery disease: a systematic review and meta-analysis.

Left ventricular mechanical dyssynchrony (LVMD) is an important prognostic factor in coronary artery disease. A growing body of evidence indicates that LVMD parameters derived from phase analysis of gated myocardial SPECT may allow risk stratification for future cardiac events. We performed a systematic review and meta-analysis on the prognostic value of LVMD on gated SPECT in patients with coronary artery disease. PubMed, Embase, and the Cochrane library were searched until August 25, 2022, for studies reporting the prognostic value of LVMD on gated SPECT for outcomes of all-cause death, cardiac death, or major adverse cardiovascular event (MACE) in patients with coronary artery disease. Hazard ratios (HRs) and their 95% confidence intervals (CIs) were meta-analytically pooled using a random-effects model. Nine studies (26,750 patients) were included in a qualitative synthesis. Among the SPECT LVMD parameters used in various studies, high phase standard deviation, phase bandwidth, and phase entropy were widely evaluated and reported to be associated with high rates of all-cause death, cardiac death, or MACE. For five studies (23,973 patients) in the quantitative synthesis, the pooled HR of LVMD for predicting MACE was 2.81 (95% CI 2.03-3.88). Studies using combined phase parameters to define LVMD showed higher HRs than a study using phase entropy (p = 0.0180). LVMD from gated myocardial SPECT is a significant prognostic factor for coronary artery disease. Phase analysis of gated SPECT may be useful for accurate risk stratification and could be applied for clinical decision-making in such patients.

Comparison of Neuromuscular Fatigue in Powerlifting Paralympics in Different Training Methods.

Mean propulsive velocity (MPV) has been associated with neuromuscular fatigue; however, its suitability for strength training in Paralympic powerlifting (PP) remains uncertain. The objective of this work was to evaluate the MPV in two training methods (traditional-TRAD and eccentric-ECC). Eleven PP athletes were evaluated pre, during the intervention and post intervention at a load of 80% of the 1RM for TRAD and 110%-80% of 1 RM for ECC. The results demonstrated that there was no significant neuromuscular fatigue for the TRAD (~5% performance loss), as well as no significant decline in MPV during the intervention. For the ECC, there is a significant reduction in MPV before and after training (~12% loss of performance). A difference between TRAD and ECC after the intervention was also identified (0.87 m/s±0.22, 95% CI 0.72-1.02 vs. 0.72±0.20, 95% CI 0.59-0.86 p=0.042, F(3.30)=10.190, η2p=0.505 - very high effect). During the intervention for ECC, no significant decline in MPV was observed. The results of this study suggest that the mechanical indices of MPV do not seem to be effective indicators of neuromuscular fatigue in the sample studied or in the context of this specific training regime, being more indicated as a control of training volume.

Experimental study on the triaxial compression mechanical performance of basalt fiber-reinforced recycled aggregate concrete after exposure to high temperature

The use of basalt fiber-reinforced recycled aggregate concrete (BFRRC) can effectively treat waste concrete and reduce the consumption of natural resources. BFRRC is often in complex triaxial compression in engineering applications and may exposure to high temperature conditions. To evaluate the conventional triaxial compression mechanical performance of BFRRC after exposure to high temperature, 324 cylindrical specimens were produced. The specimens were designed and fabricated by varying several experimental parameters: the recycled coarse aggregate replacement ratio, basalt fiber dosage, temperature, and lateral confining pressure. The specimens previously exposed to high temperature were subjected to conventional triaxial compression tests and the effects of various experimental parameters on the mechanical performance indexes of BFRRC were analyzed. The results show that the peak stress and elastic modulus of BFRRC all raise with greater fiber dosage and confining pressure but decrease with higher replacement ratio and temperature. The maximum increase of the peak stress and elastic modulus is 352.45% and 224.59%, respectively. The peak strain of BFRRC has two variation trends of gradual increase and gradual decrease with the replacement ratio rising. And the peak strain gradually grows with the temperature and confining pressure increasing. The fiber dosage, however, does not exert the considerable impact on the peak strain. The maximum increase of the peak strain is 132.22%. The research provides a scientific basis for the triaxial mechanical performance, fire resistance design, and post-disaster assessment of BFRRC, and promotes the popularization and application of BFRRC in building structures.

Nonlinear Frequency Mixing Ultrasound Imaging of Nanoscale Contrast Agents.

Nanoscale ultrasound contrast agents show promise as alternatives for diagnostics and therapies due to their enhanced stability and ability to traverse blood vessels. Nonetheless, their reduced size limits echogenicity. This study introduces an enhanced nanobubble frequency mixing ultrasound imaging method, by capitalizing on their nonlinear acoustic response to dual-frequency excitation. A single broadband transducer (L12-3v) controlled by a programmable ultrasound system was used to transmit a dual-frequency single-cycle wavefront. The frequency mixing effect enabled simultaneous transducer capture of nanobubble-generated sum and difference frequencies in real time without the need for additional hardware or post-processing, by substituting the single-frequency wavefront in a standard contrast harmonic pulse inversion imaging protocol, with the dual-frequency wavefront. Optimization experiments were conducted in tissue mimicking phantoms. Among the dual-frequency combinations that were tested, the highest contrast was obtained using 4&8 MHz. The nanobubble contrast improved with increased mechanical index, and achieved a maximal contrast improvement of 8.4 ± 0.5 dB compared to 4 MHz pulse inversion imaging. In imaging of a breast cancer tumor mouse model, after a systemic nanobubble injection, the contrast was improved by 3.4 ± 1.7, 4.8 ± 1.8, and 6.3 ± 1.6 dB for mechanical indices of 0.04, 0.08, and 0.1, respectively. Nonlinear frequency mixing significantly improved the nanobubble contrast, which facilitated their imaging in-vivo. This study offers a new avenue to enhance ultrasound imaging utilizing nanobubbles, potentially leading to advancements in other diagnostic applications.

Effects of natural zeolite on mechanical properties and durability indexes of concrete

This study evaluated the effects of a locally available natural zeolite (NZ), on properties of concrete. To the best knowledge of the authors, this paper is the first study wherein NZ concrete has been evaluated using durability index methods. The NZ studied is presently not used as pozzolan in the local cement industry, hence its potential use in concrete would be new. In the investigation, concrete mixtures of 0.50 and 0.70 water/cementitious ratios were prepared using CEM I 52.5R cement type blended with 0, 10, 20 and 30% NZ. Performance characteristics of NZ were compared with those of 20% or 30% fly ash (FA), which is a conventional pozzolan. The mechanical properties measured were strength development, workability and setting time. Durability properties including carbonation and a consortium of indexes comprising oxygen permeability index, water sorptivity index and chloride conductivity index were also tested. Interestingly, NZ concretes exhibited good or excellent durability index values and lower carbonation results, relative to those of the corresponding FA concretes. In fact, adding 20% NZ into concrete mixtures gave optimal performance, including significant reduction of carbonation, which is a unique beneficial effect as pozzolans typically increase carbonation.

The effects of prone position ventilation on patients with acute respiratory distress syndrome after cardiac surgery.

This study aimed to investigate the effects of prone position ventilation treatment on patients with acute respiratory distress syndrome (ARDS) after cardiac surgery. Clinical data were collected from 93 hospitalized patients with acute respiratory distress syndrome (ARDS) in the intensive care unit (ICU) of cardiology from February 2021 to February 2023. Patients were divided into supine position group (n = 45) and prone position group (n = 48). The difference in 28-days survival rates, blood gas indicators, respiratory mechanics indicators, and adverse events before and after treatment was analyzed. We found that within 28days of admission, 8.33% of ARDS patients in prone position group and 11.11% in supine position group died of all causes (p > .05). After treatment, the levels of arterial PaO2 (103.25 ± 9.44 in prone position group and 91.62 ± 9.18 in supine position group), PaCO2 (30.26 ± 5.54 and 36.56 ± 6.37), blood LAC (1.35 ± 0.37 and 1.68 ± 0.42), oxygenation (232.23 ± 28.56 and 205.13 ± 31.34) and diffusion index (453.48 ± 63.30 and 395.18 ± 58.54) in both groups were improved (p < .001). Moreover, the increase in prone position group was more remarkable. After treatment, the respiratory mechanics indexes of the lung compliance as well as respiratory resistance were improved (p < .05). Moreover, the increase in supine position group was more remarkable (p < .05). The incidence of atelectasis in prone position group was lower than that in supine position group (p < .05). Additionally, the alteration in other adverse events showed no significant difference between the two groups (p > .05). Taken together, prone position ventilation in patients with ARDS after cardiac surgery improved blood gas indexes, hypoxemia, and respiratory mechanics indexes, as well as reduced the incidence of atelectasis.

The impact of mechanical properties on the cutting performance of Al2O3-based ceramic cutting tools for green turning of hardened steel

The utilization of green turning as an alternative to grinding has the potential to enhance the processing efficiency of hardened steel while also preserving the environment. However, the intermittent turning of hardened steel necessitates the tool to possess exceptional comprehensive mechanical properties. Consequently, this study aimed to investigate the impact of mechanical properties on the cutting performance of three Al2O3-based ceramic cutting tools, namely SG4, CC650, and CC670 by conducting interrupted turning experiments on hardened steel at both low and high speeds. The findings revealed that for different ceramic tool, it was not the smaller the speed, the smaller the cutting force when intermittently cutting hardened steels. In general, an optimal cutting speed existed where the workpiece material softened at a faster rate than the tool material due to cutting heat, resulting in minimized main cutting forces. Consequently, during the initial cutting stage, the cutting force of CC670 measured at 110 m/min was slightly higher than that at 230 m/min. The primary failure mechanism of CC670 at high speeds was mechanical fatigue. In high-speed cutting scenarios where tool failure was not primarily caused by thermal shock, the tool CC670, possessing superior mechanical properties, demonstrated a longer lifespan. When the multiple mechanical performance indices do not consistently reach their maximum values simultaneously under the current process conditions, an ideal cutting tool structure would feature a tool nose characterized by exceptional hardness and chemical stability, while the remaining section of the cutting tool should demonstrate high fracture toughness and flexural strength.

Chitosan silver nanoparticle inspired seaweed (Gracilaria crassa) biodegradable films for seafood packaging

As an alternative to conventional plastic packaging, the concept of developing blend films with bio-based materials seems to be an environmentally friendly approach. In the present study, blend films were prepared using ethanolic extract of Gracilaria crassa (GCE) with chitosan (CS) and silver nanoparticles (AgNPs). The developed films were evaluated based on the physical, mechanical, structural, barrier and antioxidant indices. The films were slightly yellowish in color (b* ranges 39.69–53.08) and smooth textured. The FTIR spectra confirmed the intermolecular interaction between film components and the combination of CS and GCE occurred by means of -OH groups and hydrophobic interaction due to the cross-linking effect of the plasticizer (glycerol). The antioxidant properties of the films were investigated via DPPH assay and total phenolic contents showed significant improvement (p < 0.05) upon incorporation of GCE. Similar observations were made for tensile parameter (37.29 ± 1.22–38.39 ± 1.09) compared to the control (29.71 ± 1.66). The thermal pattern of blended films showed greater stability with Tg of 112.6 °C. The formulated films significantly extended the shelf-life of shrimp nuggets in refrigerated storage (4 °C) up to 9 days. The study reveals that the incorporation of GCE/AgNPs with chitosan films can be an active packaging system in the field of sustainable food packaging technology.

Orthogonal Experimental Study on the Ratio of Similar Materials of Coal Body

According to the coal samples collected from Zhaogu No.2 Coal Mine as raw coal samples, the similar materials of coal body were studied by using river sand, pulverized coal, Portland cement and calcium carbonate. The orthogonal test method of four factors (bone glue ratio, aggregate ratio, rubber ratio, water mixing rate) and three levels was used to obtain the physical and mechanical parameters such as density, uniaxial compressive strength, elastic modulus, cohesion, internal friction angle and tensile strength of coal similar materials. The range analysis method was used to obtain the key influencing factors and variation rules of the physical and mechanical properties of coal similar materials. Finally, the method of multiple linear regression analysis was used to obtain the similar material ratio that was most consistent with the mechanical properties index of raw coal. The ratio of calcium carbonate: cement: river sand: coal powder: water = 1: 5: 0.9: 5.9: 3.2. The density error, compressive strength error, elastic modulus error and cohesion error of coal sample and raw coal are small, which proves that the similar material is similar to the mechanical properties of raw coal, and provides guidance for subsequent research.