Casting Procedure Research Articles

Experimental investigation on mechanical properties of TiB2 reinforced AA6061 metal matrix composites fabricated by stir casting process

As the need for lightweight constructions rises in everyday life, metal matrix composites (MMCs) made of aluminum are used in a range of fields, including sports equipment, automotive, aerospace, and defense. Stir casting technique is the most often utilized commercially in industries among the several ways to create metal matrix composites based on aluminium because it is a quick and inexpensive process. In the present study, lightweight AA6061-TiB2 composites with varied levels (0, 1.5, 3 and 4.5 wt%) of reinforcement were created using the stir casting procedure. Microstructure and mechanical properties of the specimens were studied. The microstructure studies revealed the distribution of black Mg2Si particles along with Al-Mg-Si eutectic in alpha aluminium matrix along with of fine and small TiB2 particulates. The hardness as well as tensile characteristics of composites were dramatically improved by the addition of TiB2 particles.

Mechanical behaviour of Al6061 hybrid nanocomposites reinforced with nano alumina and molybdenum disulfide

The main goal of this research is to create and examine the mechanical behaviour of aluminium alloy 6061 composites supplemented with molybdenum disulfide (MoS2) and nano alumina (Al2O3). The reinforcements used in the composite specimens were made in a variety of quantities, including Al6061 with 5% molybdenum disulfide, Al6061 with 5% nano alumina, and Al6061 with 5% molybdenum disulfide and 5% nano alumina. Using the stir casting procedure, the composite specimens were created. The mechanical parameters of the alloy were measured and compared to those of pure Al6061 in terms of tensile strength, flexural strength, impact strength, tensile modulus, flexural modulus, and hardness. Nano alumina was added with Al6061 to enhance the strength, whereas molybdenum disulfide was added to reduce the hardness of the composites. The results reveal that the inclusion of nano alumina and MoS2 has a good effect on tensile and flexural behaviour while reducing impact strength significantly. Inclusion of MoS2 improves the toughness of the composites at the same time the other mechanical properties like tensile strength and modulus decreases. Scanning Electron Microscope was used and the micro structure of the composites was studied. The tensile and flexural strength of the Al6061 composite with 5 wt% of nano alumina was enhanced with 9.4% and 10.2% compared to pure Al6061, whereas the impact strength of Al6061 with 5 wt% MoS2 was improved by 12.8% over pure Al6061.

RARE CASE OF ACUTE LOCALIZED EXANTHEMATOUS PUSTULOSIS OVER FOREARM UNDERNEATH FIBERGLASS CAST FOR LOWER END RADIUS FRACTURE

Plaster casting is the most important tool in the practice of orthopedics. It is used to operate on fractures to treat them either permanently or afterward. Although there are disadvantages including stiffness, pressure sores, and compartment syndrome, orthopedic casting is nevertheless beneficial. Early warning indications include skin lesions like bullae and ecchymosis, as well as pain, soreness, itching, and systemic sickness that is out of proportion to the localized physical signs. The development of ALEP/AGEP is commonly within days after beginning a drug. We present a case of an uncommon orthopedic cast complication involving a previously healthy patient who developed an acute localized exanthematous pustulosis over forearm inside a fibreglass cast applied for treatment of lower end radius fracture. A less common, more localized variation of AGEP is acute localized exanthematous pustulosis, or ALEP. With the right casting procedure and routine cast reviews, all of these issues may be avoided.

Formulation and Evaluation of Chitosan-PLGA Biocomposite Scaffolds Incorporated with Quercetin Liposomes Made by QbD Approach for Improved Healing of Oral Lesions.

The current research aims to develop and evaluate chitosan-PLGA biocomposite scaffolds in combination with quercetin liposomes to accomplish the desired impact in oral lesions where pharmacotherapeutic agent treatment through circulation could only reach the low content at the target. Optimization of quercetin-loaded liposomes was carried out using 32 factorial design. The preparation of porous scaffolds comprising produced quercetin-loaded liposomes by thin-film method was carried out in the current study using a unique strategy combining solvent casting and gas foaming procedures. The prepared scaffolds were tested for physicochemical properties, in vitro quercetin release study, ex vivo drug permeation and retention research using goat mucosa, antibacterial activity, and cell migration studies on fibroblast L929 cell lines. Improved cell growth and migration were seen in the order control < liposomes < proposed system. The proposed system has been examined for its biological and physicochemical features, and it has the potential to be utilized as an efficient therapy for oral lesions.

A facile, semi-automatic protocol for the design and production of 3D printed, anatomical customized orthopedic casts for forearm fractures

Closed fractures of distal radius and ulna are one of the most common skeletal injuries, occurring at all ages. Temporary arm immobilization through cast is part of the standard treatments. However, traditional casting procedures are time consuming, operator's skill dependent and do not always guarantee a satisfactory outcome. From a clinical perspective, casts are often considered uncomfortable and can be associated to skin lesions. To overcome these limitations, the recent growth of 3D technologies has enabled new standardized casting procedures: additive manufacturing (AM) is a technique that creates highly customized cast models from anatomical 3D data by using digitally controlled and operated material laying tools. Compared with conventional casts, those produced with AM technique could potentially reduce skin complications and satisfy both mechanical and clinical requirements of functionality, comfort, and aesthetics.The objective of this study is to describe the new practical methodology to produce a 3D printable cast for upper arm immobilization. The parametric modelling tool, employed to develop a semi-automatic design system for generating the printable cast model, reduces the complex process of orthosis design to a few minutes and all the manufacturing operations remain unaffected by CAD skills of the operator. Specific hardware and software tools (3D scanner, modelling software and FDM technology) were chosen to mitigate design and production costs while guaranteeing suitable levels of data accuracy, process efficiency and design versatility. To highlight the effectiveness of the proposed solution, a finite element analysis simulation was performed on models with different geometry, highlighting the mechanical strength of generated structures.The final result is a personalized 3D printed cast with a highly ventilated structure that is lightweight but still maintains a high level of strength and provides hygienic benefits, reducing the risk of cutaneous complications, potentially improving treatment efficacy and increasing patient satisfaction.

Microstructure Characterization, Mechanical and Wear Behavior of Silicon Carbide and Neem Leaf Powder Reinforced AL7075 Alloy hybrid MMC’s.

The demanding material quality criteria in the automotive and aerospace industries have recently had an impact on the development of lightweight aluminium alloys. The choice and application of metal-matrix composites as structural materials in this context are known to offer a variety of benefits. These benefits include the ability to combine high elastic modulus, toughness, and impact resistance; minimum sensitivity to change in temperature or thermal shock; durability of the surface is good; moisture absorption leads to the potential issue while minimum exposure which leads to environmental degradation; and improved fabricability with conventional metalworking equipment. Aluminium metal matrix composites (AMMCs) are a potential material for advanced structural, aviation, aerospace, marine, and defence applications, as well as for the automotive sector and other related fields, due to their outstanding combination of qualities. The stir casting procedure is used to create an aluminium metal matrix composite (AMMC), which is the most efficient way to do so. In this study, the aluminium alloy 7075 is strengthened using neem leaf powder and SiC. The Vickers hardness examination method is used to govern the hardness of hybrid composites. Eventually, the mechanical and tribological properties of the composites were assessed, and their relationship to the composites' matching microstructure and wear was addressed.

Potentiometric Sensor Arrays Based on Hybrid PFSA/CNTs Membranes for the Analysis of UV-Degraded Drugs.

The degradation of drugs is a substantial problem since it affects the safety and effectiveness of pharmaceutical products, as well as their influence on the environment. A novel system of three potentiometric cross-sensitive sensors (using the Donnan potential (DP) as an analytical signal) and a reference electrode was developed for the analysis of UV-degraded sulfacetamide drugs. The membranes for DP-sensors were prepared by a casting procedure from a dispersion of perfluorosulfonic acid (PFSA) polymer, containing carbon nanotubes (CNTs), whose surface was preliminarily modified with carboxyl, sulfonic acid, or (3-aminopropyl)trimethoxysilanol groups. A correlation between the sorption and transport properties of the hybrid membranes and cross-sensitivity of the DP-sensor to sulfacetamide, its degradation product, and inorganic ions was revealed. The analysis of the UV-degraded sulfacetamide drugs using the multisensory system based on hybrid membranes with optimized properties did not require a pre-separation of the components. The limits of detection of sulfacetamide, sulfanilamide, and sodium were 1.8 × 10-7, 5.8 × 10-7, and 1.8 × 10-7 M. The relative errors of the determination of the components of the UV-degraded sulfacetamide drugs were 2-3% (at 6-8% relative standard deviation). PFSA/CNT hybrid materials provided the stable work of the sensors for at least one year.

Experimental Study and GRNN Modeling of Shrinkage Characteristics for Wax Patterns of Gas Turbine Blades Considering the Influence of Complex Structures

With the continuous increase in power demand in aerospace, shipping, electricity, and other industries, a series of manufacturing requirements such as high precision, complex structure, and thin wall have been put forward for gas turbines. Gas turbine blades are the key parts of the gas turbine. Their manufacturing accuracy directly affects the fuel economy of the gas turbine. Thus, how to improve the manufacturing accuracy of gas turbine blades has always been a hot research topic. In this study, we perform a quantitative study on the correlation between process parameters and the overall wax pattern shrinkage of gas turbine blades in the wax injection process. A prediction model based on a generalized regression neural network (GRNN) is developed with the newly defined cross-sectional features consisting of area, area ratio, and some discrete point deviations. In the qualitative analysis of the cross-sectional features, it is concluded that the highest accuracy of the wax pattern is obtained for the fourth group of experiments, which corresponds to a holding pressure of 18 bars, a holding time of 180 s, and an injection temperature of 62 °C. The prediction model is trained and tested based on small experimental data, resulting in an average RE of 1.5% for the area, an average RE of 0.58% for the area ratio, and a maximum MSE of less than 0.06 mm2 for discrete point deviations. Experiments show that the GRNN prediction model constructed in this study is relatively accurate, which means that the shrinkage of the remaining major investment casting procedures can also be modeled and controlled separately to obtain turbine blades with higher accuracy.

Real-Time Quality Inspection of Motor Rotor Using Cost-Effective Intelligent Edge System

Induction motors (IMs) are used extensively as driving actuators in electric vehicles. Motor rotors are prone to defects in the die casting procedure, which can significantly reduce the production quality. Benefitting from the development of Internet of Things (IoT) techniques and edge computing, this study designed an instrumentation system for the fast inspection of rotor defects to meet the objectives of efficient and high-quality rotor production. First, an electromagnetic sensing device is designed to acquire the induced voltage signal of the rotor under investigation. Second, a residual multiscale feature fusion convolutional neural network model is designed to extract the hierarchical features of the signal, to facilitate defect recognition. The developed algorithm is deployed into a cost-effective edge computing node that includes a signal acquisition circuit and a Raspberry Pi microcontroller. The conducted experimental studies show that this implementation can achieve an inference time of less than 200 ms and accuracy of more than 99%. It is shown that the designed system exhibits superior performance when compared with conventional methods. The developed, compact and flexible handheld solution with enhanced deep learning techniques shows outstanding potential for use in real-time rotor defect detection.

Insight into TEMPO-oxidized cellulose-based composites as electrochemical sensors for dopamine assessment

The diagnosis and treatment of many neurological and psychiatric problems depend on establishing simple, inexpensive, and comfortable electrochemical sensors for dopamine (DA) detection. Herein, 2,2,6,6 tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOC) were successfully loaded with silver nanoparticles (AgNPs) and/or graphite (Gr) and crosslinked by tannic acid, producing composites. This study describes a suitable casting procedure for the composite synthesis of TOC/AgNPs and/or Gr for the electrochemical detection of dopamine. Electrochemical impedance spectra (EIS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to characterize the TOC/AgNPs/Gr composites. In addition, the direct electrochemistry of electrodes treated with the prepared composites was examined using cyclic voltammetry. The TOC/AgNPs/Gr composite-modified electrode improved electrochemical performance towards detecting dopamine compared to TOC/Gr-modified electrodes. Upon employing amperometric measurement, our electrochemical instrument has a wide linear range (0.005–250 μM), a low limit of detection (0.0005 μM) at S/N = 3, and a high sensitivity (0.963 μA μM−1 cm−2). Additionally, it was demonstrated that DA detection seemed to have outstanding anti-interference characteristics. The proposed electrochemical sensors meet the clinical criteria regarding reproducibility, selectivity, stability, and recovery. The straightforward electrochemical method utilized in this paper may provide a potential framework for creating dopamine quantification biosensors.

Facile assembly of flexible quaternary SnO2/SrSnO3/Fe3O4/PVDF nanocomposites with tunable optical, electrical, and magnetic properties for promising magneto-optoelectronic applications

Facile assembly, co-precipitation, and drop casting procedures have been used to construct SnO2/SrSnO3/Fe3O4/PVDF flexible nanocomposites. SnO2/SrSnO3/Fe3O4 nanocomposites (TSF NCs') have been successfully incorporated into polyvinylidene fluoride polymers (PF), according to the microstructural exploration of the systems, which was revealed by XRD, EDX, and ATR-FTIR analysis. The FESEM and cross-section areas demonstrated that the addition of TSF NCs' to PF porous material enhanced its surface characteristics and decreased its surface roughness. The optical gap was lowered from 3.90 to 3.07 eV, and it was discovered that both the refractive index and optical conductivity had improved when TSF NCs' were incorporated into PF. According to the observations, the supplement ratios have a profound influence on the dielectric properties of the nanocomposites. Moreover, the electrical parameters of TSF/PF nanocomposite are significantly modified. The TSF/PF magnetic nanocomposite has good magnetic reactivity and can be easily extracted from the aqueous solution using an external magnetic field, as demonstrated by VSM. This research has been conducted to obtain TSF/PF nanocomposites to be used in promising magno-optoelectronic applications.

An in-depth investigation into the implications of alleviating banded microstructures on crack-tip opening displacement test of API 5LX60 linepipe steel plate

The present study seeks to fill the research gap regarding the correlation between crack-tip opening displacement (CTOD) and banded microstructures of high-strength low-alloy steel. For this purpose, a distinct casting procedure and thermo-mechanical controlled process route were implemented to produce an API 5LX60 MS linepipe steel plate free of banded microstructures and suitable for sour environments. According to the results of optical microscopy, the volume fraction of quasi-polygonal ferrite increased by 59% and the average grain size of the microstructure declined, whereas the volume fraction and size of pearlite constitute decreased compared to the API 5LX60 M linepipe steel plate, which is suitable for sweet environments. As opposed to the API 5LX60 M steel plate, no evidence of banded microstructures was observed, and in the CTOD test, the fracture was ductile with a surface exhibiting a higher percentage of side grooves. Moreover, no secondary cracks or river patterns were observed in the secondary electron imaging of the API 5LX60 MS steel plate. The CTOD and KIC fracture toughness increased from 1.32 mm to 1.73 mm and from 54.01 MPa m0.5–58.19 MPa m0.5, respectively. Moreover, the force vs. notch-opening displacement curves of both API 5LX60 M and API 5LX60 MS steel plates showed stable crack growth, with API 5LX60 MS having a higher plastic deformation prior to the final fracture. The rational correlation between the microstructure and CTOD test results of API 5LX60 MS steel plate approved improvements in this plate.

Abstract Number ‐ 127: Poly(vinyl alcohol) grafts of brain aneurysms with patient‐specific morphologies

Introduction Current animal models of brain aneurysms used for testing neuro‐interventional devices have highly simplistic vascular anatomy in comparison with human aneurysm‐parent vessel complexes. Poly(vinyl alcohol) (PVA) is a leading biomaterial for manufacture of artificial vascular grafts because of its biocompatibility, hemocompatibility, availability, low cost, moldability/castability, and tunable mechanical properties to match arterial compliance [1,2]. However, PVA is non‐cell adhesive and requires modification with additives to promote endothelialization of the luminal surface to maintain long‐term graft patency [1,3]. We have previously studied the biocompatibility of resorcinol bis(diphenyl phosphate) (RDP) coated clays blended with polymers and have found excellent cell adhesion and proliferation with human dermal fibroblasts as well as dental pulp stem cells [4]. Our overall goal is to develop a new in vivo model of brain aneurysms by manufacturing patient‐specific aneurysm anatomies with a blend of PVA and RDP clay and grafting them into animals. Here, we evaluate the casting of PVA in the shape of patient‐specific aneurysms. Methods 10% PVA (w/w) (99% hydrolyzed, 85–124K molecular weight, Sigma Aldrich) was dissolved in deionized water, to which 1% RDP clay (ICL Industrial Products, Be’er Sheva, Israel) was added. The PVA was crosslinked using 15% (w/w) of sodium trimetaphosphate and 30% (w/w) of sodium hydroxide, after which rheological studies (stress sweeps using a Bohlin Gemini rheometer) were conducted. In the casting procedure, negative molds of both simple tubes and complex aneurysm geometries were designed using Rhinoceros 3D software (Robert McNeel &amp; Associates, Seattle, WA) and 3D printed in ABS plastic. The negative mold was then filled with beeswax, resulting in a positive wax mold that was dip‐coated 8 times in PVA solution, and spun on a two‐axis spinner in between each dip to ensure even coverage. After overnight drying in a fume hood, the model was placed in heated water, allowing the wax to melt out and leaving behind the luminal PVA cast. Results Rheology on the crosslinked polymers showed that the PVA/RDP blend exhibited over twice the elastic modulus of unblended PVA (Figure A). Such enhanced mechanical properties are consistent with previous studies [5]. Both simple tubular geometries and patient‐specific anatomies were able to be successfully cast using the methodology developed here (Figure B). Conclusions This proposed casting methodology demonstrates a realistic, efficient way to replicate complex aneurysm geometries with comparatively inexpensive materials and short time frame. Future endeavors will include further exploration of the PVA/RDP biocompatibility as well as completing the casting procedure with a PVA/RDP blend.

Physical Properties of Pulp and Paper: A Comparison of Forming Procedures

Abstract In this work, we used the conventional wet papermaking process and the solution casting procedure to make paper sheets and optimized the relative content of eucalyptus and Simao pine pulps using the mechanical properties of the paper sheet as the evaluation index. The chemical composition, water retention value, zeta potential, carboxyl content, and drainage behavior of the pulp created using the optimal mass ratio for each method were measured, and the resulting paper sheets were characterized via Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and nitrogen adsorption/desorption isotherms. We found that for a ratio of eucalyptus to Simao pine pulps of 94:6 using the wet papermaking process, the mechanical properties of sheets took their optimal values, and the tear, tensile, and burst indexes and the folding endurance were equal to 4.43 mN·m2·g−1, 27.47 N·m·g−1, 1.13 kPa·m2·g−1, and 11.38 times, respectively, whereas the ratio leading to the best possible mechanical performance in the solution casting process was 88:12, and the corresponding paper sheets had tear, tensile, and burst indexes and the folding endurance of 11.73 mN·m2·g−1, 23.03 N·m·g−1, 0.68 kPa·m2·g−1, and 25.50 times, respectively. The cellulose, hemicellulose, and lignin contents of the pulp treated by the solution casting method were lower by 1.88, 3.11, and 2.67 percent, respectively, compared to that obtained via the wet papermaking process. However, the water retention value, zeta potential, and carboxyl content of the pulp obtained via solution casting were higher by 50.31, 123.41, and 50.15, percent, respectively, compared to that obtained via the wet papermaking process. The drainage time obtained via the solution casting method was one-fifth of that obtained via the wet forming process. The paper sheet prepared via the solution casting method was found to exhibit weaker hydrogen bonding, a decreased level of crystallinity (26.64% lower), and an increased compactness and N2 gas adsorption capacity (19.55% and 66.7% higher, respectively) compared to the sheet obtained via the wet papermaking process. This work shows that the physical properties of the paper prepared via the two processes considered here, using their respective optimal weight ratios of the different types of pulp, have their own advantages.

"CELLULOSE NANOFIBER/SHELLAC NANOCOMPOSITE FILMS AS COATINGS FOR PACKAGING PAPER"

"This study evaluates the efficiency of nanocomposite films prepared from cellulose nanofibers (CNF) isolated from rice straw and different ratios of shellac in terms of film properties, in addition to using a CNF/shellac mixture for coating paper sheets. The CNF/shellac nanocomposite films were prepared by the casting procedure. The weight percentage of shellac in the composition of the nanocomposite films was varied from 0 to 40%. Scanning electron microscopy was used to show the films’ morphological structure. Also, the films’ air permeability, tensile strength and water vapour permeability (WVP) were investigated. The outcomes showed that adding shellac to CNF can improve the films’ tensile strength, WVP and air permeability characteristics. The formulation chosen for coating paper contained 60% CNF and 40% shellac. Tests were done to assess the tensile and burst strength, water absorption, air permeability and water vapour permeability of coated paper sheets. SEM analysis was performed on the surface and cross-section of coated paper sheets. It was noticed that paper sheets coated with a 90-μm thick film of CNF or CNF/shellac presented enhanced tensile strength, as well as lower water absorption, air permeability and WVP, while the burst strength properties were not affected. The addition of shellac to the composite coating produced coated paper sheets with better tensile strength compared to those of paper sheets coated with CNF alone, making them a viable choice for packaging materials."

Synthesis and characterization of sulfonated polytriazoles utilizing 1,4‐bis(4‐azido‐2‐(trifluoromethyl)phenoxy)benzene for the proton exchange membrane applications

AbstractThe aromatic hydrocarbon‐based sulfonated polytriazoles have a reputation as a high‐performing polymer because of their excellent properties. This work demonstrates the synthesis of a new semi‐fluorinated diazide monomer, that is, 1,4‐bis(4‐azido‐2‐(trifluoromethyl)phenoxy)benzene (BATFB), and exploiting this compound a series of aromatic hydrocarbon‐based semi‐fluorinated sulfonated polytriazoles (BABPSSH‐60, −70, −80, −90) was synthesized utilizing the Cu(I)‐induced “click” cycloaddition polymerization reaction along with the sulfonated diazide monomer, 4,4′‐diazido‐2,2′‐stilbenesulfonic acid disodium salt tetrahydrate (DASSA) and the terminal dialkyne monomer, 4,4′‐(propane‐2,2′‐diyl)bis((prop‐2‐ynyloxy)benzene) (BPAAL). The structural analysis of those copolymers was completed by the FTIR and the NMR (1H and 13C) spectroscopic methods. Further, the degree of sulfonation (DS) and the ion exchange capacity (IEC) values of the copolymers were confirmed using the 1H NMR spectrums. They are readily soluble in respective solvents, and a light yellowish membrane was obtained using the solution casting procedure. These membranes demonstrated admissible mechanical and thermal stabilities, balanced water absorption properties, and reasonable chemical stability. The surface phase (SAXS, AFM) and bulk phase (TEM) morphological analysis proved the well‐separated phase morphology. The BABPSSH‐90 displayed a proton conductivity of 104 mS cm−1 at 90.

Optical and Color Properties of Gamma Irradiated Polyvinyl Alcohol - Sodium lignosulfonate-Cadmium sulfide Nanocomposite Films

We prepared a nanocomposite (NC) film containing sodium lignosulfonate (LS), polyvinyl alcohol (PVA) and nano-sized cadmium sulfide (CdS) using the thermolysis and ex-situ casting procedures. Samples from the prepared PVA-LS/CdS NC film were exposed to gamma radiation doses (2 − 20 kGy). To study the resultant outcome of the gamma ray irradiation on the optical and color properties of the synthesized NCs, we used UV-vis spectroscopy and the International Commission on Illumination (CIE) color changes technique. When the gamma dose was increased to 20 kGy, the refractive index increased along with a decrease in the direct optical bandgap from 4.41 to 3.90 eV. We attribute this to the dominance of crosslinking that damaged the ordered configuration and thus increased the amorphous phase. This suggests that the gamma radiation can facilitate the spreading of CdS within the composite matrix suggesting an extra compacted structure of the PVA-LS/CdS NC samples. Moreover, the values of Eg, obtained from ε″ vs. energy plots were close to those values obtained by means of Tauc’s relation, indicating that the NC films exhibited a direct allowed transition. Finally, the color changes between the pristine and irradiated samples were characterized. The pristine PVA-LS/CdS NC film exhibited substantial color differences.

Investigation of key physical properties of new La@PbS filled Poly (vinyl and pyrrolidone) nanocomposite films for opto-electronics

Polymer blends incorporated with various nanoparticles are the key components for obtaining new and advanced physical properties for a wide area of applications. Herein, poly (vinyl and pyrrolidone) blend films containing different content of La@PbS nanoparticles are well prepared by following the casting procedure. La-doped PbS nanoparticles were facile synthesized via a chemical route at low temperatures. The structure of compositions was investigated through XRD, TEM, AFM, and FTIR. UV–visible spectroscopy shows that the absorption edge is redshifted to a higher wavelength and the absorbance increases with the La@PbS content. The direct and indirect transitions in the hybrid nanocomposites (HNCs) are reduced as the influence of filling percentage. Tauc’s model and quantum theory confirmed the presence of direct optical bandgap transitions in the HNC films. Urbach energy (E u ) and refractive index were also calculated. Through Wemple–Di Domenico’s (WDD) model of single-oscillator the optical susceptibilities and nonlinear refractive index were estimated. The dielectric constant and electrical conductivity of the HNC films are influenced not only by frequency but also by the La@PbS percentage. The dominant mechanism in all films is related to barrier hopping (CBH) and follows Jonscher’s power (JP) performance.

Properties of Bacterial Copper Slag Concrete

Copper ore processing generates a large amount of copper slag, which has properties that are similar to fine aggregate. Copper slag has a promising future in the construction industry as an alternative to fine aggregate. Up to 50% of fine aggregate substitutions have been successful. The performance of copper slag concrete could be improved by microbiologically induced calcium carbonate precipitation. The impact of micro-organisms on the mechanical properties and flexural behaviour of copper slag concrete was investigated in this study. Five concrete mixtures were created by replacing varying amounts of fine aggregate with copper slag, ranging from 0% to 100%. M30 grade concrete was used, and 1% to 2% of the bacterium Bacillus subtilis by weight of cement was added during the concrete casting procedure. Specimens of different shapes, such as cubes, cylinders, and prisms, were cast and examined at 7, 14, and 28 days. When treated with micro-organisms, the test results revealed that replacing 50% to 75% of the sand with copper slag produced concrete with superior mechanical properties and a greater density. With the optimal ratio of copper slag to micro-organisms, a suitable RCC beam was formed. Load–deflection patterns of bacterial copper slag concrete were used to investigate beam flexural behaviour, and the results were compared using ABAQUS modelling. Microbiologically induced calcium carbonate precipitation can alter regular copper slag concrete, resulting in enhanced concrete performance.

CFD Comparison of the Influence of Casting of Samples on the Fiber Orientation Distribution

The main goal of this research is to show that even a small deviation from the prescribed casting method EN 14651 causes a difference in fiber orientation distribution in sample beams. A further goal is to investigate the difference in the fiber orientation between bottom and side layers, which would carry the tensile load in the in-situ situation (bottom layer) compared to testing according to EN 14651 (side layer). Nowadays, the development of the proper numerical simulations that aim to visualize the casting process of the fresh concrete flow is a promising challenge in the construction industry. To be able to predict the orientation and spatial distribution of the short fibers using numerical tools may significantly simplify the investigations of the fibered composite materials. This paper compares simulations of different casting methods of the fiber concrete mixture with various flowabilities. The casting of the testing specimen was simulated in different ways: the filling of the formwork according to EN 14651, from the center only and from one edge of the formwork using computational fluid dynamics. The influence of different casting methods in combination with four specific sets of the rheological parameters on the final fiber orientation distribution is discussed. The presented outcomes of the simulations demonstrate that even a minor change in the casting procedure can significantly alter the final characteristics of the material.