Applied Sciences

Editorial

Jump to: Research, Review, Other

2 pages, 181 KiB

Open AccessEditorial

Special Issue on Selected Papers in the Section Materials 2022

by Roberto Zivieri

Appl. Sci. 2023, 13(11), 6527; https://doi.org/10.3390/app13116527 - 26 May 2023

Viewed by 1004

Abstract

The study of materials has entailed several efforts by materials scientists to gain a deep understanding of their structural, mechanical, chemical, optical, magnetic and electronic properties and engineering applications [...] Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

Research

Jump to: Editorial, Review, Other

15 pages, 1136 KiB

Open AccessArticle

Thermo-Viscoelastic Characterization of 3D Printing Polymers

by Sung Yi, Nakyung Oh, Kyung-Eun Min, Je-Sik Shin and Cheolhee Kim

Appl. Sci. 2023, 13(5), 2876; https://doi.org/10.3390/app13052876 - 23 Feb 2023

Cited by 4 | Viewed by 1597

Abstract

Polymer materials used in 3D printing exhibit degradation of material mechanical properties when exposed to thermal environments and thermal expansions can induce residual stresses in products or molds, which may result in dimensional instability and subsequent structural failures. In this study, based on [...] Read more.

Polymer materials used in 3D printing exhibit degradation of material mechanical properties when exposed to thermal environments and thermal expansions can induce residual stresses in products or molds, which may result in dimensional instability and subsequent structural failures. In this study, based on linear thermo-viscoelastic principles, material degradation master curves, shift functions, and glass transition temperatures for four different polymers used for 3D printing techniques such as MultiJet Printing and Digital Lighting Process were measured by using a dynamic mechanical analyzer. Based on the single frequency test, the glass transition temperature was measured. In addition, dynamic measurements were carried out over a frequency range at isothermal condition and storage modulus vs. frequency curves were obtained. Then, the storage moduli curves measured at different temperatures were superposed into master curves using the frequency–temperature superposition principle and shift factors were calculated as a function of temperature. Subsequently, the complex moduli curves that were measured in the frequency were curve-fitted onto generalized Maxwell models by using the least squares method and the master curves of relaxation moduli at reference temperature were obtained. The effects of temperature, frequency, and time on dynamic moduli and relaxation behaviors of four polymers used for 3D printing were evaluated. Experimental results showed that Polymers C and D could be suitable to use at the service temperature above 100

^{°}

C and Polymer C was highly crosslinked and showed low modulus reduction after about a year. The master relaxation curves obtained through this process can be utilized to predict the long-term performance of polymer molds made by 3D printing at a given environmental condition. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

21 pages, 22708 KiB

Open AccessArticle

Mechanical and Microstructural Studies of High Performance Concrete with Condensed Silica Fume

by Piotr Smarzewski

Appl. Sci. 2023, 13(4), 2510; https://doi.org/10.3390/app13042510 - 15 Feb 2023

Cited by 12 | Viewed by 2416

Abstract

This article is an extended version of the conference paper “Influence of silica fume on mechanical and fracture properties of high performance concrete” published in Procedia Structural Integrity as a part of the Special Issue for the 3rd International Conference on Structural Integrity [...] Read more.

This article is an extended version of the conference paper “Influence of silica fume on mechanical and fracture properties of high performance concrete” published in Procedia Structural Integrity as a part of the Special Issue for the 3rd International Conference on Structural Integrity (ICSI 2019). Tests were carried out to evaluate the compressive strength, tensile splitting strength, modulus of elasticity, flexural strength, and fracture properties of high performance concretes (HPC) having different levels of condensed silica fume (CSF) replacements for cement. It was found that CSF replacement for cement by up to 25% may have a favorable effect on the mechanical properties. HPC containing CSF was characterized by quite large increases in compressive strength (up to 14%) and flexural strength (16%). However, the most significant improvements in mechanical properties were obtained for splitting tensile strength (26%) and fracture energy (30.5%). There were slight reductions up to 2% in the elastic modulus, flexural strength and fracture properties at the 25% level of CSF substitution for cement. Microstructural studies showed that the narrowest microcracks and the smallest pores in the interfacial transition zone (ITZ) between the paste and grains of aggregate occurred in the HPC having 10% CSF. In addition, a reduction of ITZ around the aggregate and the formation of more high-strength hydration products was observed in all CSF-added HPCs. The outcomes reported that CSF can successfully replace cement. It is suggested that the substitution should not exceed 20%. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

17 pages, 5716 KiB

Open AccessArticle

Fresh and Mechanical Properties of High-Performance Self-Compacting Concrete Containing Ground Granulated Blast Furnace Slag and Polypropylene Fibres

by Piotr Smarzewski

Appl. Sci. 2023, 13(3), 1975; https://doi.org/10.3390/app13031975 - 3 Feb 2023

Cited by 7 | Viewed by 3303

Abstract

The purpose of this study was to evaluate the appropriateness of polypropylene fibres (PP) to decrease the brittleness of high-performance self-compacting concrete (HPSCC). The influence of PP fibre content on the fresh and mechanical assets of PP-fibre-reinforced HPSCC was investigated. PP fibres were [...] Read more.

The purpose of this study was to evaluate the appropriateness of polypropylene fibres (PP) to decrease the brittleness of high-performance self-compacting concrete (HPSCC). The influence of PP fibre content on the fresh and mechanical assets of PP-fibre-reinforced HPSCC was investigated. PP fibres were applied with 0, 0.025, 0.05, 0.075, 0.125, 0.25% contents to the HPC blends with high cement replacement by ground granulated blast furnace slag (GGBS). The impact of PP fibre fraction on fresh properties of HPSCC, counting passing capability as well as filling parameters is discussed. In addition, the mechanical properties, i.e., compressive, splitting tensile, and flexural strengths, were evaluated after 7 and 28 days of specimens’ maturation in water. The higher content of PP fibres gradually reduced the HPSCC workability and improved the mechanical properties. The high performance of fresh and hardened ecological HPSCCs containing 46% GGBS instead of cement with 0.025–0.25% PP fibre content proves the great potential of using these composites in various applications in the construction industry. The advantages of the potential recycling of GGBS include, among others, the reduced use of cement in a durable material, reduced amount of waste in landfill and lower emission levels of greenhouse gases. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

13 pages, 3590 KiB

Open AccessArticle

Waste Cork in Metakaolin–Geopolymer Matrix: Physico-Mechanical Characterization

by Giovanni Dal Poggetto, Roberta Marchetti, Isabella Lancellotti, Cristina Leonelli and Luisa Barbieri

Appl. Sci. 2023, 13(3), 1804; https://doi.org/10.3390/app13031804 - 31 Jan 2023

Cited by 2 | Viewed by 1817

Abstract

Cork powdery waste (CW) from agglomerated cork caps manufacturing is commonly transported to waste-to-energy plants, although it could be locally exploited for lightweight building materials. The transformation of CW into a geopolymer formulation to obtain a novel composite formulation suitable for insulating panels [...] Read more.

Cork powdery waste (CW) from agglomerated cork caps manufacturing is commonly transported to waste-to-energy plants, although it could be locally exploited for lightweight building materials. The transformation of CW into a geopolymer formulation to obtain a novel composite formulation suitable for insulating panels is presented in this contribution. The geopolymer mix was based on metakaolin added to NaOH and Na silicate solutions, to which 2.4, 4.8 and 9.1 wt% (calculated upon dry metakaolin) of CW in the form of as-received powdery waste were added. No pre-treatments were performed on CW and no thermal curing was conducted for the alkali-activated product that was consolidated at room temperature to improve product sustainability. The insulating panel presented an apparent density of about 1.521 to 0.990 ± 0.001 g/cm³, combined with a total porosity in the range of 35.61 to 56.22 ± 0.003 % for 2.4 to 9.1 wt% of CW, respectively, and this was dependent upon ageing time. The values of its mechanical properties (compressive strength ranged from 2.5 to 1.5 MPa at 28 and 90 days of curing time, complying with UNI EN 998-2) and thermal insulating properties (thermal conductivity around 0.1146 W/mK) indicated that the highest percentage of CW in the formulations, i.e., 9.1 wt%, was suitable to obtain self-standing insulating panels. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

13 pages, 2873 KiB

Open AccessFeature PaperArticle

Electrochemical and Economic Analysis of No-Rinse, “True-Cr-Free” Surface Conversion Coatings for a Green, Cost-Saving, Corrosion Protection of 8079 Aluminium Alloy

by Annalisa Acquesta, Ciro Sinagra and Tullio Monetta

Appl. Sci. 2023, 13(3), 1560; https://doi.org/10.3390/app13031560 - 25 Jan 2023

Cited by 3 | Viewed by 1661

Abstract

Increasing the corrosion resistance of aluminium alloys using surface treatments while reducing the processes’ environmental impact and saving natural resources has become an urgent need. Some companies that typically use pollutant substances in their process lines have started to test low-environmental-impact products. This [...] Read more.

Increasing the corrosion resistance of aluminium alloys using surface treatments while reducing the processes’ environmental impact and saving natural resources has become an urgent need. Some companies that typically use pollutant substances in their process lines have started to test low-environmental-impact products. This paper shows the results obtained using two commercial products for the conversion coating of AA8079 rolled-samples: the first, rinse, containing CrIII (the so-called “Cr-free” products), the second one, no-rinse, utterly free of Cr, based on hexafluorotitanate and dihydrogen hexafluorozirconate. The bare conversion-coated, and organic-coating-covered samples were compared with each other, evaluating their corrosion resistance when immersed in NaCl 3.5 wt.% aqueous solution. The experimental results showed that the completely Cr-free no-rinse conversion coatings demonstrate performance comparable to that of the so-called “Cr-free”. In addition, a comparison of the amount of water used in the “rinse” and the “no-rinse” industrial process is reported. Finally, an estimation of the economic balance for the process is presented, considering the waste reduction to be disposed of and the water quantity used. The aim of this paper was to demonstrate that some commercial conversion-coating products, completely free of Cr and no-rinse, are available nowadays, showing good protective properties and low environmental-impact, while guaranteeing an economic saving which is not negligible. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

18 pages, 4616 KiB

Open AccessArticle

A Simple Method to Convert Cellular Polymers into Auxetic Metamaterials

by Xiao Yuan Chen, Royale S. Underhill and Denis Rodrigue

Appl. Sci. 2023, 13(2), 1148; https://doi.org/10.3390/app13021148 - 14 Jan 2023

Cited by 4 | Viewed by 2004

Abstract

The objective of this study was to present a simple and environmentally friendly process combining low pressure (vacuum) and mechanical compression to convert low-density polyethylene (LDPE) foams into low-density foams (76–125 kg/m³) with negative tensile and compressive Poisson’s ratios (NPR). As [...] Read more.

The objective of this study was to present a simple and environmentally friendly process combining low pressure (vacuum) and mechanical compression to convert low-density polyethylene (LDPE) foams into low-density foams (76–125 kg/m³) with negative tensile and compressive Poisson’s ratios (NPR). As a first step, four series of recycled LDPE foams (electronics packaging) with starting densities of 16, 21, 30 and 36 kg/m³ were used to determine the effect of different processing conditions including temperature and pressure. Based on the optimized conditions, the tensile and compressive Poisson ratios of the resulting auxetic foams reached −2.89 and −0.66, while the tensile and compressive modulus of the auxetic foams reached 40 kPa and 2.55 kPa, respectively. The foam structure of the samples was characterized via morphological analysis and was related to the mechanical properties before and after the treatment (i.e., foams with positive and negative Poisson’s ratios). The tensile and compressive properties (Young’s modulus, strain energy, energy dissipation and damping capacity) for these auxetic foams were also discussed and were shown to be highly improved. These auxetic foams can be applied in sports and military protective equipment. To the best of our knowledge, there is only one report on vacuum being used for the production of auxetic foams. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

15 pages, 3488 KiB

Open AccessArticle

Rejuvenating Agents vs. Fluxing Agents: Their Respective Mechanisms of Action on Bitumen Subjected to Multiple Aging Cycles

by Abraham A. Abe, Paolino Caputo, Shahin Eskandarsefat, Valeria Loise, Michele Porto, Eugenia Giorno, Loretta Venturini and Cesare Oliviero Rossi

Appl. Sci. 2023, 13(2), 698; https://doi.org/10.3390/app13020698 - 4 Jan 2023

Cited by 3 | Viewed by 2007

Abstract

During the service life of road pavements, the asphalt, more specifically the surface layer, is susceptible to aging due to the oxidation phenomenon and the loss of the volatile compounds of bitumen, which functions as the binder in the asphalt conglomerate. Road pavements [...] Read more.

During the service life of road pavements, the asphalt, more specifically the surface layer, is susceptible to aging due to the oxidation phenomenon and the loss of the volatile compounds of bitumen, which functions as the binder in the asphalt conglomerate. Road pavements that undergo a significant level of oxidation become rigid and susceptible to cracking, and new paving operations will need to be carried out in order to make the road ideal for continued use. However, due to recent eco-friendly initiatives that have been put in place to promote a circular economy and also mitigate the problem of environmental pollution, the asphalt industry is currently devising means of safeguarding the environment while also minimizing the cost of the production of road pavements without compromising their quality. As a general solution to this issue, old asphalt pavements are removed and recycled as reclaimed asphalt (RA), with the aim of restoring the original properties of the binder in such a way that RA can be re-used in combination with virgin materials to produce new road pavements. In this research study, virgin bitumen is subjected to a cycle of aging, after which two recycling agents are used to modify the aged bitumen samples. These samples containing the different recycling agents were subjected to a second aging cycle, a second recycling agent treatment, and then again subjected to a final aging cycle. The two recycling agents have different compositions, and each one of them could be either a rejuvenating agent or a fluxing agent. This study investigates the effect of these recycling agents on aged bitumen, and how the addition of these recycling agents influences the changes observed between virgin, aged and recycled bitumen. This would enable an understanding of rejuvenation and fluxing mechanisms, which will help in the classification of the asphalt recycling agents as either rejuvenating or fluxing agents. Dynamic shear rheology, atomic force microscopy, and light microscopy to determine asphaltene melting point were the techniques used in this investigation. The results obtained demonstrate that rejuvenating agents are more effective in reversing the effects of oxidative aging on the bitumen binder than fluxing agents. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

21 pages, 6051 KiB

Open AccessArticle

Cutting Force When Machining Hardened Steel and the Surface Roughness Achieved

by Karel Osička, Jan Zouhar, Petra Sliwková and Josef Chladil

Appl. Sci. 2022, 12(22), 11526; https://doi.org/10.3390/app122211526 - 13 Nov 2022

Cited by 3 | Viewed by 2045

Abstract

This article deals primarily with the problem of determining the cutting force when machining hardened steels. For this study, the steel used was 100 Cr6, number 1.3505. The secondary aspects of the study focused on the evaluation of the surface quality of machined [...] Read more.

This article deals primarily with the problem of determining the cutting force when machining hardened steels. For this study, the steel used was 100 Cr6, number 1.3505. The secondary aspects of the study focused on the evaluation of the surface quality of machined samples and the recommendation of cutting conditions. A wide variety of components are used in engineering, the final heat treatment of which is hardening. These components are usually critical in a particular product. The quality of these components determines the correct functioning of the entire body of technical equipment, and ultimately, its service life. In our study, these are the core parts of thrust bearings, specifically the rolling elements. The subject of this experiment involves machining these components in the hardened state with cubic boron nitride tools and the continuous measurement of the cutting force using a dynamometer. The machining is carried out on a conventional lathe. A total of 12 combinations of cutting conditions were set. Specifically, for three cutting speeds of 130, 155 and 180 m·min⁻¹, the feed rates of 0.05 and 0.1 mm·rev⁻¹ and the cutting widths of 0.2 and 0.35 mm, were evaluated The evaluation assessed the surface quality by both touch and non-touch methods. A structural equation with the appropriate constants and exponents was then constructed from the data obtained using the dynamometer. The experiment confirmed the potential of achieving a value of the average arithmetic profile deviation Ra in the range of 0.3–0.4 when turning hardened steels with cubic boron nitride. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

37 pages, 16030 KiB

Open AccessArticle

Numerical Investigation of Different Core Topologies in Sandwich-Structured Composites Subjected to Air-Blast Impact

by Marcel Walkowiak, Ulf Reinicke and Denis Anders

Appl. Sci. 2022, 12(18), 9012; https://doi.org/10.3390/app12189012 - 8 Sep 2022

Cited by 4 | Viewed by 2195

Abstract

Air-blast loading is a serious threat to military and civil vehicles, buildings, containers, and cargo. Applications of sandwich-structured composites have attracted increasing interest in modern lightweight design and in the construction of dynamic loading regimes due to their high resistance against blast and [...] Read more.

Air-blast loading is a serious threat to military and civil vehicles, buildings, containers, and cargo. Applications of sandwich-structured composites have attracted increasing interest in modern lightweight design and in the construction of dynamic loading regimes due to their high resistance against blast and ballistic impacts. The functional properties of such composites are determined by the interplay of their face sheet material and the employed core topology. The core topology is the most important parameter affecting the structural behavior of sandwich composites. Therefore, this contribution presents a thorough numerical investigation of different core topologies in sandwich-structured composites subjected to blast loading. Special emphasis is put on prismatic and lattice core topologies displaying auxetic and classical non-auxetic deformation characteristics in order to illustrate the beneficial properties of auxetic core topologies. Their dynamic responses, elastic and plastic deformations, failure mechanisms, and energy absorption capabilities are numerically analyzed and compared. The numerical studies are performed by means of the commercial finite element code ABAQUS/Explicit, including a model for structural failure. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

16 pages, 8909 KiB

Open AccessArticle

Development of TiO₂-Based Photocatalyst Supported on Ceramic Materials for Oxidation of Organic Pollutants in Liquid Phase

by Sadjo Danfá, Cátia Oliveira, Regina Santos, Rui C. Martins, Margarida M. J. Quina and João Gomes

Appl. Sci. 2022, 12(15), 7941; https://doi.org/10.3390/app12157941 - 8 Aug 2022

Cited by 7 | Viewed by 2028

Abstract

Water scarcity is one of the major concerns of this century. The photocatalysis through TiO₂ can be suitable for improving liquid wastewater treatment. However, TiO₂ is used as a powder (nanoparticles), which is a drawback for full-scale applications. To overcome this, [...] Read more.

Water scarcity is one of the major concerns of this century. The photocatalysis through TiO₂ can be suitable for improving liquid wastewater treatment. However, TiO₂ is used as a powder (nanoparticles), which is a drawback for full-scale applications. To overcome this, in the present work, powder TiO₂ was impregnated on ceramic material. Several parameters, such as support cleanliness, support load, TiO₂ suspension concentration, powder dispersion in a solvent, contact method, and drying temperature, were evaluated on the impregnation method. The influence of TiO₂ concentration in suspensions was tested from 1 to 10% w/w. The results showed that the preparation conditions impact the TiO₂ impregnation yield. The 10%TiO₂/Leca was the most effective in photocatalysis but had a relevant loss of TiO₂ from the support by erosion. For 3.6%TiO₂/Leca and 5%TiO₂/Leca, at TiO₂ concentrations of 86.6 and 102.5 mg/L promoted 71 to 85% of sulfamethoxazole removal in 6 h under UVA radiation, respectively. Scanning electron microscopy (SEM) revealed the TiO₂ adhesion onto the surface of the ceramic material, and the thickness of the TiO₂ layer over the support can attain 7.64 to 10.9 μm. The work showed that the TiO₂ impregnation method over Leca could be suitable for obtaining cost-effective photocatalysts. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

8 pages, 2439 KiB

Open AccessArticle

Recycling of Wastes Deriving from the Production of Epoxy-Carbon Fiber Composites in the Production of Polymer Composites

by Andrea Saccani, Maurizio Fiorini and Stefania Manzi

Appl. Sci. 2022, 12(9), 4287; https://doi.org/10.3390/app12094287 - 24 Apr 2022

Cited by 8 | Viewed by 1884

Abstract

The formulation of composites reinforced with shredded epoxy-carbon fibers wastes is investigated. Poly (buthylene terephthalate) PBT was selected as the matrix for the composites. In order to increase the interaction between the epoxy resin still coating the carbon fibers and the PBT matrix, [...] Read more.

The formulation of composites reinforced with shredded epoxy-carbon fibers wastes is investigated. Poly (buthylene terephthalate) PBT was selected as the matrix for the composites. In order to increase the interaction between the epoxy resin still coating the carbon fibers and the PBT matrix, polycarbonate (PC) was added either to the matrix formulation or as a waste coating. The flexural strength, impact strength, and dynamic-mechanical analysis of the new composites was investigated, as well as their microstructure by scanning electron microscopy. Experimental results show that the recycled fibers can be dispersed in both pure PBT and in its blend, enhancing the mechanical properties of the composites. An increase in the investigated properties is found specifically in the elastic modulus below 50 °C and in the impact strength. The extent of the increase depends on the obtained microstructure. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

10 pages, 2498 KiB

Open AccessFeature PaperArticle

Synthesis and Characterisation of Alginate-Based Capsules Containing Waste Cooking Oil for Asphalt Self-Healing

by Jose Norambuena-Contreras, Jose L. Concha, Luis E. Arteaga-Pérez and Irene Gonzalez-Torre

Appl. Sci. 2022, 12(5), 2739; https://doi.org/10.3390/app12052739 - 7 Mar 2022

Cited by 19 | Viewed by 3071

Abstract

This paper presents the synthesis and characterisation of biopolymeric capsules for asphalt self-healing. A sodium alginate biopolymer extracted from the cell wall of brown algae was used as the encapsulating material to contain Waste Cooking Oil (WCO) as a potential encapsulated rejuvenating agent [...] Read more.

This paper presents the synthesis and characterisation of biopolymeric capsules for asphalt self-healing. A sodium alginate biopolymer extracted from the cell wall of brown algae was used as the encapsulating material to contain Waste Cooking Oil (WCO) as a potential encapsulated rejuvenating agent for aged bitumen. Polynuclear capsules were synthesised by ionic gelation. The size, surface aspect and internal structure of the WCO capsules were evaluated using Optical and Scanning Electron Microscopy. The physical-chemical properties and thermal stability of the WCO capsules and their components were also evaluated. Moreover, the diffusion process and self-healing capability of the released WCO on cracked bitumen test samples were determined by image analysis through fluorescence microscopy. The main results of this study showed that the WCO capsules presented a suitable morphology to be mixed in asphalt mixtures. WCO capsules and their components presented mechanical and thermal stability and physical-chemical properties which suggest their feasibility for self-healing applications. It was proven that the encapsulated WCO can diffuse in the aged bitumen, reducing its viscosity and promoting the self-healing of microcracks. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

41 pages, 14464 KiB

Open AccessArticle

In Silico Studies of Tumor Targeted Peptide-Conjugated Natural Products for Targeting Over-Expressed Receptors in Breast Cancer Cells Using Molecular Docking, Molecular Dynamics and MMGBSA Calculations

by Lucy R. Hart, Charlotta G. Lebedenko, Saige M. Mitchell, Rachel E. Daso and Ipsita A. Banerjee

Appl. Sci. 2022, 12(1), 515; https://doi.org/10.3390/app12010515 - 5 Jan 2022

Cited by 7 | Viewed by 4513

Abstract

In this work, in silico studies were carried out for the design of diterpene and polyphenol-peptide conjugates to potentially target over-expressed breast tumor cell receptors. Four point mutations were induced into the known tumor-targeting peptide sequence YHWYGYTPQN at positions 1, 2, 8 and [...] Read more.

In this work, in silico studies were carried out for the design of diterpene and polyphenol-peptide conjugates to potentially target over-expressed breast tumor cell receptors. Four point mutations were induced into the known tumor-targeting peptide sequence YHWYGYTPQN at positions 1, 2, 8 and 10, resulting in four mutated peptides. Each peptide was separately conjugated with either chlorogenate, carnosate, gallate, or rosmarinate given their known anti-tumor activities, creating dual targeting compounds. Molecular docking studies were conducted with the epidermal growth factor receptor (EGFR), to which the original peptide sequence is known to bind, as well as the estrogen receptor (ERα) and peroxisome proliferator-activated receptor (PPARα) using both Autodock Vina and FireDock. Based on docking results, peptide conjugates and peptides were selected and subjected to molecular dynamics simulations. MMGBSA calculations were used to further probe the binding energies. ADME studies revealed that the compounds were not CYP substrates, though most were Pgp substrates. Additionally, most of the peptides and conjugates showed MDCK permeability. Our results indicated that several of the peptide conjugates enhanced binding interactions with the receptors and resulted in stable receptor-ligand complexes; Furthermore, they may successfully target ERα and PPARα in addition to EGFR and may be further explored for synthesis and biological studies for therapeutic applications. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Graphical abstract

16 pages, 1748 KiB

Open AccessArticle

Experimental Methodology to Determine Thermal Conductivity of Nanofluids by Using a Commercial Transient Hot-Wire Device

by Jose I. Prado, Uxía Calviño and Luis Lugo

Appl. Sci. 2022, 12(1), 329; https://doi.org/10.3390/app12010329 - 30 Dec 2021

Cited by 16 | Viewed by 2738

Abstract

The lack of a standard experimental procedure to determine thermal conductivity of fluids is noticeable in heat transfer processes from practical and fundamental perspectives. Since a wide variety of techniques have been used, reported literature data have huge discrepancies. A common practice is [...] Read more.

The lack of a standard experimental procedure to determine thermal conductivity of fluids is noticeable in heat transfer processes from practical and fundamental perspectives. Since a wide variety of techniques have been used, reported literature data have huge discrepancies. A common practice is using manufactured thermal conductivity meters for nanofluids, which can standardize the measurements but are also somewhat inaccurate. In this study, a new methodology to perform reliable measurements with a recent commercial transient hot-wire device is introduced. Accordingly, some extensively studied fluids in the literature (water, ethylene glycol, ethylene glycol:water mixture 50:50 vol%, propylene glycol, and n-tetradecane) covering the range 0.100 to 0.700 W m⁻¹ K⁻¹ were used to check the device in the temperature range 283.15 to 333.15 K. Deviations between the collected data and the theoretical model, and repeatabilities and deviations between reported and literature values, were analyzed. Systematic deviations in raw data were found, and a correction factor depending on the mean thermal conductivity was proposed to operate with nanofluids. Considering all tested effects, the expanded (k = 2) uncertainty of the device was set as 5%. This proposed methodology was also checked with n-hexadecane and magnesium-oxide-based n-tetradecane nanofluids. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

20 pages, 7914 KiB

Open AccessArticle

Development of a Novel Design Strategy for Moving Mechanisms Used in Multi-Material Plastic Injection Molds

by Fátima de Almeida, Vitor F. C. Sousa, Francisco J. G. Silva, Raúl D. S. G. Campilho and Luís P. Ferreira

Appl. Sci. 2021, 11(24), 11805; https://doi.org/10.3390/app112411805 - 12 Dec 2021

Cited by 4 | Viewed by 4949

Abstract

Plastics injection molding is a sector that is becoming increasingly competitive due to the environmental issues it entails, pressuring consumers to reduce its use. Thus, plastics processing companies attempt to minimize costs, with the aim of increasing competitiveness. This pressure is transmitted to [...] Read more.

Plastics injection molding is a sector that is becoming increasingly competitive due to the environmental issues it entails, pressuring consumers to reduce its use. Thus, plastics processing companies attempt to minimize costs, with the aim of increasing competitiveness. This pressure is transmitted to the mold manufacturers, as the mold conditions the equipment that it is used for, which may have significantly different amortization costs. The present work aimed to design a novel mechanism able to deal with the necessary movements in 2K injection molding in a more compact way. A novel hybrid mechanical and hydraulic movement was developed. More compact movements lead to smaller molds, which can be used on smaller injection machines, leading to reduced costs. This methodology consists of multiplying a disproportionate movement to the mold through several movements, which results in a slightly more complex, but much more compact, system for molds devoted to multi-material injected parts. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

9 pages, 2064 KiB

Open AccessArticle

Ultrafast Electron Dynamics in Magnetic Thin Films

by Hovan Lee, Cedric Weber, Manfred Fähnle and Mostafa Shalaby

Appl. Sci. 2021, 11(20), 9753; https://doi.org/10.3390/app11209753 - 19 Oct 2021

Cited by 4 | Viewed by 2060

Abstract

In past decades, ultrafast spin dynamics in magnetic systems have been associated with heat deposition from high energy laser pulses, limiting the selective access to spin order. Here, we use a long wavelength terahertz (THz) pump–optical probe setup to measure structural features in [...] Read more.

In past decades, ultrafast spin dynamics in magnetic systems have been associated with heat deposition from high energy laser pulses, limiting the selective access to spin order. Here, we use a long wavelength terahertz (THz) pump–optical probe setup to measure structural features in the ultrafast time scale. We find that complete demagnetization is possible with <6 THz pulses. This occurs concurrently with longitudinal acoustic phonons and an electronic response. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

Review

Jump to: Editorial, Research, Other

22 pages, 3501 KiB

Open AccessReview

Evaluation and Current State of Primary and Secondary Zinc Production—A Review

by Henryk Kania and Mariola Saternus

Appl. Sci. 2023, 13(3), 2003; https://doi.org/10.3390/app13032003 - 3 Feb 2023

Cited by 35 | Viewed by 8478

Abstract

This article presents the history of zinc, its production and demand. The quantity of zinc production, both primary zinc from ores and concentrates, and secondary zinc from scrap and zinc-rich waste, was discussed. A comprehensive economic analysis covers zinc prices in the years [...] Read more.

This article presents the history of zinc, its production and demand. The quantity of zinc production, both primary zinc from ores and concentrates, and secondary zinc from scrap and zinc-rich waste, was discussed. A comprehensive economic analysis covers zinc prices in the years 1960–2021. The basic methods of obtaining zinc from ores, including pyrometallurgical (Imperial Smelting Process ISP, Kivcet, Ausmelt) and hydrometallurgical (roasting–leaching–electrowinning RLE, atmospheric direct leaching ADL, Engitec Zinc Extraction EZINEX, zinc pressure leach) and their short characteristics, are presented. The global zinc market and the main areas of its application were analyzed. Technologies used for the recovery of zinc from scrap are discussed along with their characteristics. Galvanized steel is the main source of secondary zinc, both in the galvanizing process and in the remelting of galvanized steel. It can be easily recycled with other scrap steel in the electric arc furnace (EAF) for steel production. Currently, with high volatility in the price of zinc, as well as its natural resources in the earth’s crust, recycling is an important activity, despite the fact that zinc concentrates have a relatively constant chemical composition, while the resulting zinc waste contains zinc in varying amounts. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

26 pages, 4198 KiB

Open AccessReview

Light-Induced Advanced Oxidation Processes as PFAS Remediation Methods: A Review

by Domenico Leonello, Murilo Alexandre Fendrich, Francesco Parrino, Nainesh Patel, Michele Orlandi and Antonio Miotello

Appl. Sci. 2021, 11(18), 8458; https://doi.org/10.3390/app11188458 - 12 Sep 2021

Cited by 27 | Viewed by 7914

Abstract

PFAS substances, which have been under investigation in recent years, are certainly some of the most critical emerging contaminants. Their presence in drinking water, correlated with diseases, is consistently being confirmed by scientific studies in the academic and health sectors. With the aim [...] Read more.

PFAS substances, which have been under investigation in recent years, are certainly some of the most critical emerging contaminants. Their presence in drinking water, correlated with diseases, is consistently being confirmed by scientific studies in the academic and health sectors. With the aim of developing new technologies to mitigate the water contamination problem, research activity based on advanced oxidation processes for PFAS dealkylation and subsequent mineralization is active. While UV radiation could be directly employed for decontamination, there are nevertheless considerable problems regarding its use, even from a large-scale perspective. In contrast, the use of cheap, robust, and green photocatalytic materials active under near UV-visible radiation shows interesting prospects. In this paper we take stock of the health problems related to PFAS, and then provide an update on strategies based on the use of photocatalysts and the latest findings regarding reaction mechanisms. Finally, we detail some brief considerations in relation to the economic aspects of possible solutions. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

Other

Jump to: Editorial, Research, Review

7 pages, 235 KiB

Open AccessPerspective

Coordination Energetic Materials—Scientific Curiosity or Future of Energetic Material Applications?

by Klaudia Pawlus, Tomasz Jarosz and Agnieszka Stolarczyk

Appl. Sci. 2022, 12(20), 10498; https://doi.org/10.3390/app122010498 - 18 Oct 2022

Cited by 3 | Viewed by 1322

Abstract

Significant incentives for developing and introducing new energetic materials to the industrial-scale production and application of new energetic materials have stimulated extensive research on the subject. Despite numerous studies, which have reported a broad array of results, progress in this field remains limited [...] Read more.

Significant incentives for developing and introducing new energetic materials to the industrial-scale production and application of new energetic materials have stimulated extensive research on the subject. Despite numerous studies, which have reported a broad array of results, progress in this field remains limited as the research results do not translate into commensurate practical applications. Coordination energetic materials are one of the promising classes of such materials. Despite more than two decades of research efforts dedicated to these substances and their advantages over classical energetic materials, in terms of performance parameters and safety parameters, these materials have not found any broader practical application. In this work, selected representative literature reports dedicated to these materials have been analysed in order to present the possible reasons for this state. Some suggestions about the future direction of research and development efforts dedicated to coordination energetic materials have also been formulated. The publication is one voice in the discussion on new challenges related to the search for new lead-free explosives. Full article

(This article belongs to the Special Issue Selected Papers in the Section Materials 2022)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Selected Papers in the Section Materials 2022

Share This Special Issue

Special Issue Editor

Special Issue Information

Benefits of Publishing in a Special Issue

Published Papers (20 papers)

Editorial

Research

Review

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI