bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatio-Temporal Evolution Characteristics and Spatial Interaction Spillover Effects of New-Urbanization and Green Land Utilization Efficiency
Authors: Wang Shuai , Yang Cunyi , Li Zhenghui
Published: October 2021

In the context of vigorously promoting new-urbanization, effectively improving the green use efficiency of urban land is an inevitable requirement to achieve high-quality economic and social development. Based on the panel data from 2011 to 2018 of 297 prefecture-level and above cities in China, this paper uses the entropy weight method and the super-efficient SBM-GML model to estimate the spatio-temporal evolution characteristics of new-urbanization and urban green land utilization efficiency. Then, the spatial simultaneous-equation and the generalized spatial three-stage least square method (GS3SLS) are employed to empirically investigate the spatial interaction spillover effects between the new-urbanization and the green land utilization efficiency. The results indicate that: (1) The level of new-urbanization and the green land utilization efficiency in Chinese cities have common and complex temporal and spatial dynamic evolution characteristics. (2) There are mutual inhibition effects between new-urbanization and green land utilization efficiency, and the level of new-urbanization is in a comparatively leading role. (3) Both the level of new-urbanization and green land utilization efficiency have obvious spatial spillover effects. (4) The level of new-urbanization of surrounding regions promotes the green land utilization efficiency of local regions, and the improvement of the green land utilization efficiency of surrounding regions also promotes the level of new-urbanization of local regions. As environmental pressure increasingly becomes a constraint on urban development, these findings are helpful to clarify the regional relationship between urban construction and green development and promote the harmonious development of new-urbanization and green land utilization efficiency.
Cell Populations Expressing Stemness-Associated Markers in Lung Adenocarcinoma
Authors: Paterson Claudia , Kilmister Ethan J. , Brasch Helen D. , Bockett Nicholas , Patel Josie , Paterson Erin , Purdie Gordon , Galvin Sean , Davis Paul F. , Itinteang Tinte , Tan Swee T.
Published: October 2021

The stemness-associated markers OCT4, NANOG, SOX2, KLF4 and c-MYC are expressed in numerous cancer types suggesting the presence of cancer stem cells (CSCs). Immunohistochemical (IHC) staining performed on 12 lung adenocarcinoma (LA) tissue samples showed protein expression of OCT4, NANOG, SOX2, KLF4 and c-MYC, and the CSC marker CD44. In situ hybridization (ISH) performed on six of the LA tissue samples showed mRNA expression of OCT4, NANOG, SOX2, KLF4 and c-MYC. Immunofluorescence staining performed on three of the tissue samples showed co-expression of OCT4 and c-MYC with NANOG, SOX2 and KLF4 by tumor gland cells, and expression of OCT4 and c-MYC exclusively by cells within the stroma. RT-qPCR performed on five LA-derived primary cell lines showed mRNA expression of all the markers except SOX2. Western blotting performed on four LA-derived primary cell lines demonstrated protein expression of all the markers except SOX2 and NANOG. Initial tumorsphere assays performed on four LA-derived primary cell lines demonstrated 0–80% of tumorspheres surpassing the 50 µm threshold. The expression of the stemness-associated markers OCT4, SOX2, NANOG, KFL4 and c-MYC by LA at the mRNA and protein level, and the unique expression patterns suggest a putative presence of CSC subpopulations within LA, which may be a novel therapeutic target for this cancer. Further functional studies are required to investigate the possession of stemness traits.
Performance of Self-Healing Cementitious Composites Using Aligned Tubular Healing Fiber
Authors: Mu Ru , Soro Dogniman Landry , Wang Xiaowei , Qing Longbang , Cao Guorui , Mei Shaolin , Liu Yongshuai
Published: October 2021

From the perspective of improving the self-healing method in construction, a tubular healing fiber was adopted as a container to improve the encapsulation capacity, which was available using a micro-capsule as a container. Knowing the direction of the stresses to which structure members are subjected, this research investigated the influence of aligning tubular healing fibers parallel to intended stress into a cementitious composite to increase the self-healing capability. For that, a healing agent was encapsulated into a tubular healing fiber made with polyvinylidene of fluoride resin (PVDF). Then, the healing fiber was combined with steel fibers to align both fibers together parallel to the direction of an intended splitting tensile stress when subjected to a magnetic field in a cylindrical cementitious composite. The alignment method and the key point through which the alignment of the healing fibers could efficiently improve autonomic self-healing were investigated. Since the magnetic field is known to be able to drag steel to an expected direction, steel fibers were combined with the healing fibers to form a hybrid fiber that aligned both fibers together. The required mixture workability was investigated to avoid the sinking of the healing fibers into the mixture. The healing efficiency, according to the orientation of the healing fibers in the composite matrix, was evaluated through a permeability test and a repetitive splitting tensile test. The aligned healing fibers performed better than the randomly distributed healing fibers. However, according to the healing efficiency with aligned healing fibers, it was deduced that the observed decreasing effect of the container’s alignment on the specimen’s mechanical properties was low enough to be neglected.
Wear Analysis of Materials Used for a Track Steering System in Abrasive Soil Mass
Authors: Olejniczak Klaudia , Napiórkowski Jerzy
Published: October 2021

This paper presents the results of comparative research on materials used for a track steering system in an abrasive soil mass. Two types of elastomer tracks were tested: a steel-rubber stave from an asphalt paver and a rubber overlay used in vehicles with a steel track chain. The results obtained were related to the wear of Hadfield steel. The tests were carried out on a “spinning bowl” stand in a natural soil mass, which consisted of two types of soil: light and heavy. It was shown that the resistance to abrasive wear depended on the grain size of the worked soil and the chemical composition of the materials. Rubber overlay was found to have the highest resistance index in all types of soils. It was made of high-density polyethylene, low-density polyethylene, ethylene acrylate/ethyl copolymer (ethylene acrylate 18%) and ethylene/propylene copolymer with an ethylene content of 60%. An analysis of the condition of the machined surfaces after friction tests complements the results presented.
Corrosion Inhibition Mechanism of Steel Reinforcements in Mortar Using Soluble Phosphates: A Critical Review
Authors: Bastidas David M. , Martin Ulises , Bastidas Jose M. , Ress Jacob
Published: October 2021

The corrosion inhibition mechanism of soluble phosphates on steel reinforcement embedded in mortar fabricated with ordinary Portland cement (OPC) are reviewed. This review focuses soluble phosphate compounds, sodium monofluorophosphate (Na2PO3F) (MFP), disodium hydrogen phosphate (Na2HPO4) (DHP) and trisodium phosphate (Na3PO4) (TSP), embedded in mortar. Phosphate corrosion inhibitors have been deployed in two different ways, as migrating corrosion inhibitors (MCI), or as admixed corrosion inhibitors (ACI). The chemical stability of phosphate corrosion inhibitors depends on the pH of the solution, H2PO4− ions being stable in the pH range of 3–6, the HPO42− in the pH range of 8–12, while the PO43− ions are stable above pH 12. The formation of iron phosphate compounds is a thermodynamically favored spontaneous reaction. Phosphate ions promote ferrous phosphate precipitation due to the higher solubility of ferric phosphate, thus producing a protective barrier layer that hinders corrosion. Therefore, the MFP as well as the DHP and TSP compounds are considered anodic corrosion inhibitors. Both types of application (MCI and ACI) of phosphate corrosion inhibitors found MFP to present the higher inhibition efficiency in the following order MFP > DHP > TSP.
Metaheuristic Prediction of the Compressive Strength of Environmentally Friendly Concrete Modified with Eggshell Powder Using the Hybrid ANN-SFL Optimization Algorithm
Authors: Tosee Seyed Vahid Razavi , Faridmehr Iman , Bedon Chiara , Sadowski Łukasz , Aalimahmoody Nasrin , Nikoo Mehdi , Nowobilski Tomasz
Published: October 2021

The aim of this article is to predict the compressive strength of environmentally friendly concrete modified with eggshell powder. For this purpose, an optimized artificial neural network, combined with a novel metaheuristic shuffled frog leaping optimization algorithm, was employed and compared with a well-known genetic algorithm and multiple linear regression. The presented results confirm that the highest compressive strength (46 MPa on average) can be achieved for mix designs containing 7 to 9% of eggshell powder. This means that the strength increased by 55% when compared to conventional Portland cement-based concrete. The comparative results also show that the proposed artificial neural network, combined with the novel metaheuristic shuffled frog leaping optimization algorithm, offers satisfactory results of compressive strength predictions for concrete modified using eggshell powder concrete. Moreover, it has a higher accuracy than the genetic algorithm and the multiple linear regression. This finding makes the present method useful for construction practice because it enables a concrete mix with a specific compressive strength to be developed based on industrial waste that is locally available.
Research on the Hot Deformation Behavior of the Casting NiTi Alloy
Authors: Tao Chengchuang , Huang Hongjun , Zhou Ge , Zheng Bowen , Zuo Xiaojiao , Chen Lijia , Yuan Xiaoguang
Published: October 2021

The hot deformation behavior and processing maps of the casting NiTi alloy were studied at the deformation temperature of 650–1050 °C and the strain rate of 5 × 10−3–1 s−1 by Gleeble-3800 thermal simulating tester. The variation of the strain rate sensitivity exponent m and the activation energy Q under different deformation conditions (T = 650–1050 °C, ε˙ = 0.005–1 s−1) were obtained. The formability of the NiTi alloy was the best from 800 °C to 950 °C. The constitutive equation of the casting NiTi alloy was constructed by the Arrhenius model. The processing map of the casting NiTi alloy was plotted according to the dynamic material model (DMM) based on the Prasad instability criterion. The optimal processing areas were at 800–950 °C and 0.005–0.05 s−1. The microstructure of the casting NiTi alloy was analyzed by TEM, SEM and EBSD. The softening mechanisms of the casting NiTi alloy were mainly dynamic recrystallization of the Ti2Ni phase and the nucleation and growth of fine martensite.
Synthesis and Characterization of Carbon and Carbon-Nitrogen Doped Black TiO2 Nanomaterials and Their Application in Sonophotocatalytic Remediation of Treated Agro-Industrial Wastewater
Authors: Rahman Saifur , Nawaz Rab , Khan Javed Akbar , Ullah Habib , Irfan Muhammad , Glowacz Adam , Lyp-Wronska Katarzyna , Wzorek Lukasz , Asif Khan Mohammad Kamal , Jalalah Mohammed , Alsaiari Mabkhoot A. , Almawgani Abdulkarem H.
Published: October 2021

The conventional open ponding system employed for palm oil mill agro-effluent (POME) treatment fails to lower the levels of organic pollutants to the mandatory standard discharge limits. In this work, carbon doped black TiO2 (CB-TiO2) and carbon-nitrogen co-doped black TiO2 (CNB-TiO2) were synthesized via glycerol assisted sol-gel techniques and employed for the remediation of treated palm oil mill effluent (TPOME). Both the samples were anatase phase, with a crystallite size of 11.09–22.18 nm, lower bandgap of 2.06–2.63 eV, superior visible light absorption ability, and a high surface area of 239.99–347.26 m2/g. The performance of CNB-TiO2 was higher (51.48%) compared to only (45.72%) CB-TiO2. Thus, the CNB-TiO2 is employed in sonophotocatalytic reactions. Sonophotocatalytic process based on CNB-TiO2, assisted by hydrogen peroxide (H2O2), and operated at an ultrasonication (US) frequency of 30 kHz and 40 W power under visible light irradiation proved to be the most efficient for chemical oxygen demand (COD) removal. More than 90% of COD was removed within 60 min of sonophotocatalytic reaction, producing the effluent with the COD concentration well below the stipulated permissible limit of 50 mg/L. The electrical energy required per order of magnitude was estimated to be only 177.59 kWh/m3, indicating extreme viability of the proposed process for the remediation of TPOME.
Effect of TiO2 Concentration on Microstructure and Properties of Composite Cu–Sn–TiO2 Coatings Obtained by Electrodeposition
Authors: Kasach Aliaksandr A. , Kharytonau Dzmitry S. , Paspelau Andrei V. , Ryl Jacek , Sergievich Denis S. , Zharskii Ivan M. , Kurilo Irina I.
Published: October 2021

In this work, Cu–Sn–TiO2 composite coatings were electrochemically obtained from a sulfate bath containing 0–10 g/L of TiO2 nanoparticles. The effect of TiO2 particles on kinetics of cathodic electrodeposition has been studied by linear sweep voltammetry and chronopotentiometry. As compared to the Cu–Sn alloy, the Cu–Sn–TiO2 composite coatings show rougher surfaces with TiO2 agglomerates embedded in the metal matrix. The highest average amount of included TiO2 is 1.7 wt.%, in the case of the bath containing 5 g/L thereof. Composite coatings showed significantly improved antibacterial properties towards E. coli ATCC 8739 bacteria as compared to the Cu–Sn coatings of the same composition. Such improvement has been connected with the corrosion resistance of the composites studied by linear polarization and electrochemical impedance spectroscopy. In the bacterial media and 3% NaCl solutions, Cu–Sn–TiO2 composite coatings have lower corrosion resistance as compared to Cu–Sn alloys, which is caused by the nonuniformity of the surface.
Zinc Oxide Nanoparticles Enhanced Biomass and Zinc Content and Induced Changes in Biological Properties of Red Perilla frutescens
Authors: Salachna Piotr , Mizielińska Małgorzata , Płoszaj-Witkowska Beata , Jaszczak Agnieszka
Published: October 2021

The above-ground parts of plants, including leaves, constitute an important part of a human diet. Their mineral and biological composition can be modified by proper preparation of the soil substrate, i.e., supplying it with nutrients. The objective of this study was to assess the influence of zinc oxide nanoparticles (ZnO NPs) at 0, 50, 100 and 200 mg L−1 concentrations on red perilla (Perilla frutescens var. crispa f. purpurea) leaf yield and quality. Plants were grown in 2 L pot under a plastic greenhouse condition. The exposure to ZnO NPs increased leaf fresh and dry weight and leaf Zn content as compared with untreated control. Fresh weight boost was the most pronounced at 50 mg L−1 ZnO NPs. The lowest concentration of ZnO NPs also enhanced the content of total polyphenols, antioxidant activity, and antiradical activity. Treatments with 50 or 100 mg L−1 ZnO NPs boosted the level of total anthocyanins and bacteriostatic activity of 25% extracts. Overall, this study demonstrated that ZnO NPs at low rates is useful as a biostimulant and nanofertilizer for red perilla production.
Investigation on Microstructure, Nanohardness and Corrosion Response of Laser Cladded Colmonoy-6 Particles on 316L Steel Substrate
Authors: Natarajan Jeyaprakash , Yang Che-Hua , Karuppasamy Sundara Subramanian
Published: October 2021

316L steel is predominantly used in manufacturing the components of high-pressure boilers, heat exchangers, aerospace engines, oil and gas refineries, etc. Its notable percentage of chromium offers resistance against corrosion and is mostly implemented in harsh environments. However, long-term exposure to these components in such environments can reduce their corrosion resistance property. Particularly at high temperatures, the oxide film formed on this type of steel reacts with the chloride, sulfides, sulfates, fluorides and forms intermetallic compounds which affect its resistance, followed by failures and losses. This work is focused on investigating the hardness, microstructure and corrosion resistance of the laser cladded Colmonoy-6 particles on the 316L steel substrate. The cladded specimens were dissected into cubic shapes and the microstructure present in the cladded region was effectively analyzed using the FESEM along with the corresponding EDS mapping. For evaluating the hardness of the cladded samples, the nanoindentation technique was performed using the TI980 TriboIndenter and the values were measured. The potentiodynamic polarization curves were plotted for both the substrate and clad samples at 0, 18, 42 and 70 h for revealing the corrosion resistance behavior. In addition, the EIS analysis was carried out to further confirm the resistance offered by the samples. The surface roughness morphology was evaluated after the corrosion process using the laser microscope, and the roughness values were measured and compared with the substrate samples. The result showed that the cladded samples experience greater hardness, lower values of surface roughness and provide better corrosion resistance when compared with substrate samples. This is due to the deposition of precipitates of chromium-rich carbide and borides that enhances the above properties and forms a stable passive film that resists corrosion during the corrosion process.
Effect of Material Heterogeneity on Environmentally Assisted Cracking Growth Rate of Alloy 600 for Safe-End Welded Joints
Authors: Zhao Kuan , Wang Shuai , Xue He , Wang Zheng
Published: October 2021

Environmentally assisted cracking (EAC) is essential in predicting light water reactors’ structural integrity and service life. Alloy 600 (equivalent to Inconel 600) has excellent corrosion resistance and is often used as a welding material in welded joints, but material properties of the alloy are heterogeneous in the welded zone due to the complex welding process. To investigate the EAC crack growth behavior of Alloy 600 for safe-end welded joints, the method taken in this paper concerns the probability prediction of the EAC crack growth rate. It considers the material heterogeneity, combining the film slip-dissolution/oxidation model, and the elastic-plastic finite element method. The strain rate at the crack tip is a unique factor to describe the mechanical state. Still, it is challenging to accurately predict it because of the complicated and heterogeneous material microstructure. In this study, the effects of material heterogeneity on the EAC crack growth behavior are statistically analyzed. The results show that the material heterogeneity of Alloy 600 can not be ignored because it affects the prediction accuracy of the crack growth rate. The randomness of yield strength has the most influence on the EAC growth rate, while Poisson’s ratio has the smallest.
Mechanical Comparison of a Novel Hybrid and Commercial Dorsal Double Plating for Distal Radius Fracture: In Vitro Fatigue Four-Point Bending and Biomechanical Testing
Authors: Liu Hsuan-Chih , Zeng Yu-Hui , Lin Chun-Li
Published: October 2021

This study compares the absolute and relative stabilities of a novel hybrid dorsal double plating (HDDP) to the often-used dorsal double plating (DDP) under distal radius fracture. The “Y” shape profile with 1.6 mm HDDP thickness was obtained by combining weighted topology optimization and finite element (FE) analysis and fabricated using Ti6Al4V alloy to perform the experimental tests. Static and fatigue four-point bending testing for HDDP and straight L-plate DDP was carried out to obtain the corresponding proof load, strength, and stiffness and the endurance limit (passed at 1 × 106 load cycles) based on the ASTM F382 testing protocol. Biomechanical fatigue tests were performed for HDDP and commercial DDP systems fixed on the composite Sawbone under physiological loads with axial loading, bending, and torsion to understand the relative stability in a standardized AO OTA 2R3A3.1 fracture model. The static four-point bending results showed that the corresponding average proof load values for HDDP and DDPs were 109.22 N and 47.36 N, that the bending strengths were 1911.29 N/mm and 1183.93 N/mm, and that the bending stiffnesses were 42.85 N/mm and 4.85 N/mm, respectively. The proof load, bending strength and bending stiffness of the HDDPs were all significantly higher than those of DDPs. The HDDP failure patterns were found around the fourth locking screw hole from the proximal site, while slight plate bending deformations without breaks were found for DDP. The endurance limit was 76.50 N (equal to torque 1338.75 N/mm) for HDDP and 37.89 N (equal to torque 947.20 N/mm) for DDP. The biomechanical fatigue test indicated that displacements under axial load, bending, and torsion showed no significant differences between the HDDP and DDP groups. This study concluded that the mechanical strength and endurance limit of the HDDP was superior to a commercial DDP straight plate in the four-point bending test. The stabilities on the artificial radius fractured system were equivalent for novel HDDP and commercial DDP under physiological loads in biomechanical fatigue tests.
Synthesis, Characterization and Antibacterial Application of Copolymers Based on N,N-Dimethyl Acrylamide and Acrylic Acid
Authors: Nakan Ulantay , Bieerkehazhi Shayahati , Tolkyn Balgyn , Mun Grigoriy A. , Assanov Mukhit , Nursultanov Merey E. , Rakhmetullayeva Raikhan K. , Toshtay Kainaubek , Negim El-Sayed , Ydyrys Alibek
Published: October 2021

Hydrogel copolymers based on N,N-dimethyl acrylamide (DMA) and acrylic acid (AAc) were synthesized using a solution polymerization technique with different monomer ratios and ammonium persulfate as an initiator. This paper investigates the thermal stability, physical and chemical properties of the hydrogel copolymer. Testing includes Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and elemental analysis (CHNS). The copolymer composition was determined by elemental analysis, and the reactivity ratios of monomers were calculated through linearization methods such as Fineman–Ross (FR), inverted Fineman–Ross (IFR), Kelen–Tudos (KT) and Mayo–Lewis (ML). Good agreement was observed between the results of all four methods. The ratio of r1 and r2 were 0.38 (r1) and 1.45 (r2) (FR), 0.38 (r1) and 1.46 (r2) (IFR), 0.38 (r1) and 1.43 (r2) (KT), and 0.38 (r1) and 1.45 (r2) (ML). Hydrogel copolymers exhibited good thermal stability, and SEM showed three-dimensional porous structures. Antibiotic-free and antibiotic-loaded hydrogels demonstrated antimicrobial properties against both Gram-positive and Gram-negative bacteria. As the ratio of DMA in hydrogel copolymer increased, the activity of copolymer against bacteria enhanced. The results indicated that these hydrogels have the potential to be used as antibacterial materials.
A Terahertz Detector Based on Double-Channel GaN/AlGaN High Electronic Mobility Transistor
Authors: Meng Qingzhi , Lin Qijing , Han Feng , Jing Weixuan , Wang Yangtao , Jiang Zhuangde
Published: October 2021

A double-channel (DC) GaN/AlGaN high-electron-mobility transistor (HEMT) as a terahertz (THz) detector at 315 GHz frequency is proposed and fabricated in this paper. The structure of the epitaxial layer material in the detector is optimized, and the performance of the GaN HEMT THz detector is improved. The maximum responsivity of 10 kV/W and minimum noise equivalent power (NEP) of 15.5 pW/Hz0.5 are obtained at the radiation frequency of 315 GHz. The results are comparable to and even more promising than the reported single-channel (SC) GaN HEMT detectors. The enhancement of THz response and the reduction of NEP of the DC GaN HEMT detector mainly results from the interaction of 2DEG in the upper and lower channels, which improves the self-mixing effect of the detector. The promising experimental results mean that the proposed DC GaN/AlGaN HEMT THz detector is capable of the practical applications of THz detection.
Characterization and Microstructural Evolution of Continuous BN Ceramic Fibers Containing Amorphous Silicon Nitride
Authors: Li Yang , Ge Min , Yu Shouquan , Zhang Huifeng , Huang Chuanbing , Kong Weijia , Wang Zhiguang , Zhang Weigang
Published: October 2021

Boron nitride (BN) ceramic fibers containing amounts of silicon nitride (Si3N4) were prepared using hybrid precursors of poly(tri(methylamino)borazine) (PBN) and polycarbosilane (PCS) via melt-spinning, curing, decarburization under NH3 to 1000 °C and pyrolysis up to 1600 °C under N2. The effect of Si3N4 contents on the microstructure of the BN/Si3N4 composite ceramics was investigated. Series of the BN/Si3N4 composite fibers containing various amounts of Si3N4 from 5 wt% to 25 wt% were fabricated. It was found that the crystallization of Si3N4 could be totally restrained when its content was below 25 wt% in the BN/Si3N4 composite ceramics at 1600 °C, and the amorphous BN/Si3N4 composite ceramic could be obtained with a certain ratio. The mean tensile strength and Young’s modulus of the composite fibers correlated positively with the Si3N4 mass content, while an obvious BN (shell)/Si3N4 (core) was formed only when the Si3N4 content reached 25 wt%.
Quantum Chemical Analysis of the Corrosion Inhibition Potential by Aliphatic Amines
Authors: Malinowski Szymon , Wróbel Michał , Woszuk Agnieszka
Published: October 2021

Destructive corrosion processes lead to the loss of primary mechanical properties of metal construction materials, which generates additional costs during their maintenance connected with repairs and protection. The effectiveness of corrosion inhibitors can be determined by using many methods, in particular quantum chemical modeling. The subject of the theoretical analyses presented in this work involves the anticorrosion properties of amines with various chemical structures. Evaluation of the corrosion inhibition properties of selected amines was performed on the basis of the HOMO–LUMO energy gap, dipole moment (µ), electronegativity (χ) determined as a result of the energy of the highest occupied molecular orbital (HOMO) and the energy of the lowest unoccupied molecular orbital (LUMO). Moreover, the HSAB (Hard and Soft Acids and Bases) theory was used to explain the reactivity of the analyzed amines, while the Mulliken population analysis was used to determine their electrostatic interactions with the surface of protected metal. The obtained results indicate that the protonation reaction of aliphatic amines leads to a change in the nature of the formation of a coordination bond with the surface of the protected metal. In turn, the quantum chemical calculations showed that the protonation reaction of aliphatic amines leads to a decrease in their corrosion inhibition efficiency. Most of the analyzed parameters indicated that tertiary amines are characterized by the highest corrosion inhibition efficiency.
Microcapsule-Type Self-Healing Protective Coating That Can Maintain Its Healed State upon Crack Expansion
Authors: Lee Ji-Sun , Kim Hyun-Woo , Lee Jun-Seo , An Hyun-Soo , Chung Chan-Moon
Published: October 2021

The purpose of this study was to develop a microcapsule-type self-healing coating system that could self-heal cracks and then maintain the healed state even upon crack expansion. Mixtures consisting of a photoinitiator and two methacrylate components, bismethacryloxypropyl-terminated polydimethylsiloxane (BMT-PDMS) and monomethacryloxypropyl-terminated PDMS (MMT-PDMS), were transformed into viscoelastic semi-solids through photoreaction. The viscoelasticity of the reacted mixtures could be controlled by varying the mass ratio of the two methacrylates. Through a stretchability test, the optimal composition mixture was chosen as a healing agent. Microcapsules loaded with the healing agent were prepared and dispersed in a commercial undercoating to obtain a self-healing coating formulation. The formulation was applied onto mortar specimens, and then cracks were generated in the coating by using a universal testing machine (UTM). Cracks with around a 150-μm mean width were generated and were allowed to self-heal under UV light. Then, the cracks were expanded up to 650 μm in width. By conducting a water sorptivity test at each expanded crack width, the self-healing efficiency and capability of maintaining the healed state were evaluated. The B-M-1.5-1-based coating showed a healing efficiency of 90% at a 150-μm crack width and maintained its healing efficiency (about 80%) up to a 350-μm crack width. This self-healing coating system is promising for the protection of structural materials that can undergo crack formation and expansion.
Fabricated CAD/CAM Post-Core Using Glass Fiber-Reinforced Resin Shows Innovative Potential in Restoring Pulpless Teeth
Authors: Suzaki Naoko , Yamaguchi Satoshi , Nambu Eriko , Tanaka Ryousuke , Imazato Satoshi , Hayashi Mikako
Published: October 2021

The prevention of root fractures of pulpless teeth is an important clinical issue to maintain healthy teeth through lifetime. The aim of this study was to examine a clinically effective treatment method for strengthening vulnerable pulpless teeth using CAD/CAM (computer-aided design/computer-aided manufacturing) fiber-reinforced post-core by conducting a fracture resistance test. A post-core made with a fiber-reinforced resin disk TRINIA (TR, SHOFU, Kyoto, Japan) was fabricated using a CAD/CAM system. The fiber-layer orientation of the CAD/CAM post-core was parallel to the axis of the restored tooth. A post-core using a conventional composite and a fiber post (CF) was also prepared. A fracture resistance test of teeth restored with the post-cores and zirconia crowns was conducted using a universal testing machine, and fracture patterns were identified by micro-CT observation. The fracture load of the roots restored with TR was 1555.9 ± 231.8 N, whereas that of CF was 1082.1 ± 226.7 N. The fracture load of TR was 43.8% that was significantly higher than that of CF (Student’s t-test, p < 0.05). The restored teeth with CAD/CAM resin post-core were found to be repairable even after fracture. These results suggest that the CAD/CAM indirect fiber post-core has the potential to strengthen the vulnerable pulpless teeth.
The Effect of Different Condition of Pulpal Pressure on Microtensile Bond Strength of Several Dentin Bonding Agents on Deep and Superficial Dentin
Authors: Montanari Marco , Fiorillo Luca , Cervino Gabriele , Sambataro Sergio , Herford Alan Scott , Cicciù Marco
Published: October 2021

The objective of this study was to examine the effect of different conditions of simulated hydrostatic pulpal pressure on the μTBS of HEMA-based and HEMA-free dentin bonding agents (DBAs). The influence of dentin location (deep and superficial) on μTBS was also evaluated. Flat coronal dentin surfaces of extracted human molars were prepared. Three groups of resin-bonded specimens were exposed to different pulpal pressures. Pulpal pressure was maintained for 20 min for each group. A flowable resin composite was used for coronal build-up. The bonded teeth were sectioned and, after 24 h of water storage, stressed to failure using the microtensile tester (μTBS). Failed samples were analyzed by SEM inspection. HEMA-based DBAs were much more sensitive to pulpal pressure conditions than non-HEMA-containing DBAs. Pulpal pressure had a greater influence in deep dentin. The HEMA-free DBA was insensitive to the presence or absence of pulpal pressure condition. SEM inspection confirmed a relationship between the presence of voids inside the HEMA-based DBAs layer and the lower μTBS results. HEMA-based DBAs are more sensitive to pulpal pressure conditions than HEMA-free DBAs. Interestingly, HEMA-free DBA showed a greater number of water droplets at resin–dentin interface in all tested conditions.
Alumina and Zirconia-Reinforced Polyamide PA-12 Composites for Biomedical Additive Manufacturing
Authors: Nakonieczny Damian S. , Kern Frank , Dufner Lukas , Antonowicz Magdalena , Matus Krzysztof
Published: October 2021

This work aimed to prepare a composite with a polyamide (PA) matrix and surface-modified ZrO2 or Al2O3 to be used as ceramic fillers (CFs). Those composites contained 30 wt.% ceramic powder to 70 wt.% polymer. Possible applications for this type of composite include bioengineering applications especially in the fields of dental prosthetics and orthopaedics. The ceramic fillers were subjected to chemical surface modification with Piranha Solution and suspension in 10 M sodium hydroxide and Si3N4 to achieve the highest possible surface development and to introduce additional functional groups. This was to improve the bonding between the CFs and the polymer matrix. Both CFs were examined for particle size distribution (PSD), functional groups (FTIR), chemical composition (XPS), phase composition (XRD), and morphology and chemical composition (SEM/EDS). Filaments were created from the powders prepared in this way and were then used for 3D FDM printing. Samples were subjected to mechanical tests (tensility, hardness) and soaking tests in a high-pressure autoclave in artificial saliva for 14, 21, and 29 days.
The Influence of the Type of Electrolyte in the Modifying Solution on the Protective Properties of Vinyltrimethoysilane/Ethanol-Based Coatings Formed on Stainless Steel X20Cr13
Authors: Kucharczyk Aleksandra , Adamczyk Lidia , Miecznikowski Krzysztof
Published: October 2021

The paper reports the results of the examination of the protective properties of silane coatings based on vinyltrimethoxysilane (VTMS) and ethanol (EtOH), doped with the following electrolytes: acetic acid (AcOH), lithium perchlorate LiClO4, sulphuric acid (VI) H2SO4 and ammonia NH3. The coatings were deposited on stainless steel X20Cr13 by the sol–gel dip-coating method. The obtained VTMS/EtOH/Electrolyte coatings were characterized in terms of corrosion resistance, surface morphology and adhesion to the steel substrate. Corrosion tests were conducted in sulphate media acidified up to pH = 2 with and without chloride ions Cl−, respectively. The effectiveness of corrosion protection was determined using potentiometric curves. It has been demonstrated that the coatings under study slow down the processes of corrosion of the steel substrate, thus effectively protecting it against corrosion.
Renovation Effect of Flax FRP-Reinforced Cracked Concrete Slabs under Impact Loadings
Authors: Wang Wenjie , Mo Zonglai , Chouw Nawawi , Jayaraman Krishnan
Published: October 2021

The impact behaviour of flax fibre-reinforced polymer (FFRP) renovated coconut fibre-reinforced concrete (CFRC) slabs was investigated through two series of experiments and theoretical analysis. The first experiment was carried out to find out the effectiveness of FFRP retrofitted method for the partly damaged concrete structure and its performance under impact loadings. The renovation process was applied on the pre-cracked rectangular CFRC slabs of 600 mm × 300 mm × 50 mm with FFRP laminates, before the repeated impact tests. Then, the parameters of these slabs, i.e., impact force history, deflection history and damage pattern, were discussed in detail. Another experiment was conducted on the FFRP-CFRC square slabs with a dimension of 600 mm × 600 mm × 50 mm. Based on test results, the effect of different FFRP configurations was discussed to find out the effective reinforcement method. In addition, the two-degree-of-freedom spring-mass model was applied to predict the impact force. Results demonstrate that FFRP composites have a good potential to be utilised as renovated construction materials under dynamic load conditions.
Mud-Based Construction Material: Promising Properties of French Gravel Wash Mud Mixed with Byproducts, Seashells and Fly Ash as a Binder
Authors: El Mendili Yassine , Bouasria Manal , Benzaama Mohammed-Hichem , Khadraoui Fouzia , Le Guern Malo , Chateigner Daniel , Gascoin Stéphanie , Bardeau Jean-François
Published: October 2021

The French gravel industry produces approximatively 6.5 million tons of gravel wash mud each year. This material offers very promising properties which require an in-depth characterization study before its use as a construction material, otherwise it is removed from value cycles by disposal in landfills. We examined the suitability of gravel wash mud and seashells, with fly ash as a binder, as an unfired earth construction material. Thermal and mechanical characterizations of the smart mixture composed of gravel wash mud, Crepidula fornicata shells and fly ash are performed. The new specimens exhibit high compressive strengths compared to usual earth construction materials, which appears as a good opportunity for a reduction in the thickness of walls. The use of fly ash and Crepidula shells in addition to gravel wash mud provides high silica and calcium contents, which both react with clay, leading to the formation of tobermorite and Al-tobermorite as a result of a pozzolanic reaction. Considering the reduction in porosity and improvements in strength, these new materials are good candidates to contribute significantly to the Sustainable Development Goals (SDGs) and reduce carbon emissions.
Histologic and Histomorphometric Evaluation of a New Bioactive Liquid BBL on Implant Surface: A Preclinical Study in Foxhound Dogs
Authors: Ferrés-Amat Eduard , Al Madhoun Ashraf , Ferrés-Amat Elvira , Al Demour Saddam , Ababneh Mera A. , Ferrés-Padró Eduard , Marti Carles , Carrio Neus , Barajas Miguel , Atari Maher
Published: October 2021

Background: Bioactive chemical surface modifications improve the wettability and osseointegration properties of titanium implants in both animals and humans. The objective of this animal study was to investigate and compare the bioreactivity characteristics of titanium implants (BLT) pre-treated with a novel bone bioactive liquid (BBL) and the commercially available BLT-SLA active. Methods: Forty BLT-SLA titanium implants were placed in in four foxhound dogs. Animals were divided into two groups (n = 20): test (BLT-SLA pre-treated with BBL) and control (BLT-SLA active) implants. The implants were inserted in the post extraction sockets. After 8 and 12 weeks, the animals were sacrificed, and mandibles were extracted, containing the implants and the surrounding soft and hard tissues. Bone-to-implant contact (BIC), inter-thread bone area percentage (ITBA), soft tissue, and crestal bone loss were evaluated by histology and histomorphometry. Results: All animals were healthy with no implant loss or inflammation symptoms. All implants were clinically and histologically osseo-integrated. Relative to control groups, test implants demonstrated a significant 1.5- and 1.7-fold increase in BIC and ITBA values, respectively, at both assessment intervals. Crestal bone loss was also significantly reduced in the test group, as compared with controls, at week 8 in both the buccal crests (0.47 ± 0.32 vs 0.98 ± 0.51 mm, p < 0.05) and lingual crests (0.39* ± 0.3 vs. 0.89 ± 0.41 mm, p < 0.05). At week 12, a pronounced crestal bone loss improvement was observed in the test group (buccal, 0.41 ± 0.29 mm and lingual, 0.54 ± 0.23 mm). Tissue thickness showed comparable values at both the buccal and lingual regions and was significantly improved in the studied groups (0.82–0.92 mm vs. 33–48 mm in the control group). Conclusions: Relative to the commercially available BLT-SLA active implants, BLT-SLA pre-treated with BBL showed improved histological and histomorphometric characteristics indicating a reduced titanium surface roughness and improved wettability, promoting healing and soft and hard tissue regeneration at the implant site.
Modeling and Analysis of a SiC Microstructure-Based Capacitive Micro-Accelerometer
Authors: Tian Xiang , Sheng Wei , Guo Zhanshe , Xing Weiwei , Tang Runze
Published: October 2021

In this study, a comb-type capacitive accelerometer based on a silicon carbide (SiC) microstructure is presented and investigated by the finite element method (FEM). It has the advantages of low weight, small volume, and low cross-coupling. Compared with silicon(111) accelerometers with the same structure, it has a higher natural frequency. When the accelerometer vibrates, its resistive force consists of two main components: a viscous damping and an elastic damping force. It was found that viscous damping dominates at low frequency, and elastic damping dominates at high frequency. The second-order linear system of the accelerometer was analyzed in the time-frequency domain, and its dynamic characteristics were best when the gap between the capacitive plates was 1.23 μm. The range of this accelerometer was 0–100 g, which is 1.64 times that of a silicon(111) accelerometer with the same structure. In addition, the accelerometer could work normally at temperatures of up to 1200 °C, which is much higher than the working temperatures of silicon devices. Therefore, the proposed accelerometer showed superior performance compared to conventional silicon-based sensors for inertial measurements.
Mirror-like Bright Al-Mn Coatings Electrodeposition from 1-Ethyl-3 Methylimidazolium Chloride-AlCl3-MnCl2 Ionic Liquids with Pyridine Derivatives
Authors: Peng Dong , Cong Dalong , Song Kaiqiang , Ding Xingxing , Wang Xuan , Bai Yixin , Yang Xinrui , Yin Changqing , Zhang Yuxin , Rao Jinsong , Zhang Min , Li Zhongsheng
Published: October 2021

The effects of three pyridine derivative additives, 4-hydroxypyridine, 4-picolinic acid, and 4-cyanopyridine, on Al-Mn coatings were investigated in 1-ethyl-3-methylimidazolium chloride-AlCl3-MnCl2 (EMIC-AlCl3-MnCl2) ionic liquids. The smooth mirror-like bright Al-Mn coatings were obtained only in the EMIC-AlCl3-MnCl2 ionic liquids containing 4-cyanopyridine, while the matte Al-Mn coatings were electrodeposited from EMIC-AlCl3-MnCl2 without additives or containing either 4-hydroxypyridine or 4-picolinic acid. The scanning electron microscope and X-ray diffraction showed that the bright Al-Mn coatings consisted of nanocrystals and had a strong (200) preferential orientation, while the particle size of matte Al-Mn coatings were within the micron range. The brightening mechanism of 4-cyanopyridine is due to it being adsorbed onto the cathode to produce the combined effect of (1) generating an overpotential to promote Al-Mn nucleation; (2) inhibiting the growth of the deposited nuclei and enabling them grow preferentially, making the coating composed of nanocrystals and with a smooth surface. The brightening effect of 4-cyanopyridine on the Al-Mn coatings was far better than that of the 4-hydroxypyridine and the 4-picolinic acid. In addition, the bright Al-Mn coating was prepared in a bath with 6 mmol·L−1 4-cyanopyridine and displayed superior corrosion resistance relative to the matte coatings, which could be attributed to its unique nanocrystalline structure that increased the number of grain boundaries and accelerated the formation of the protective layer of the corrosion products.
Synthesis and Bioactivity of Ancorinoside B, a Marine Diglycosyl Tetramic Acid
Authors: Soliga Kevin J. , Bär Sofia I. , Oberhuber Natalie , Zeng Haoxuan , Schrey Hedda , Schobert Rainer
Published: October 2021

The sponge metabolite ancorinoside B was prepared for the first time in 16 steps and 4% yield. It features a β-d-galactopyranosyl-(1→4)-β-d-glucuronic acid tethered to a d-aspartic acid-derived tetramic acid. Key steps were the synthesis of a fully protected d-lactose derived thioglycoside, its attachment to a C20-aldehyde spacer, functionalization of the latter with a terminal N-(β-ketoacyl)-d-aspartate, and a basic Dieckmann cyclization to close the pyrrolidin-2,4-dione ring with concomitant global deprotection. Ancorinoside B exhibited multiple biological effects of medicinal interest. It inhibited the secretion of the cancer metastasis-relevant matrix metalloproteinases MMP-2 and MMP-9, and also the growth of Staphylococcus aureus biofilms by ca 87% when applied at concentrations as low as 0.5 µg/mL. This concentration is far below its MIC of ca 67 µg/mL and thus unlikely to induce bacterial resistance. It also led to a 67% dispersion of preformed S. aureus biofilms when applied at a concentration of ca 2 µg/mL. Ancorinoside B might thus be an interesting candidate for the control of the general hospital, catheter, or joint protheses infections.
Heterocornols from the Sponge-Derived Fungus Pestalotiopsis heterocornis with Anti-Inflammatory Activity
Authors: Lei Hui , Bi Xiaoxu , Lin Xiuping , She Jianglian , Luo Xiaowei , Niu Hong , Zhang Dan , Yang Bin
Published: October 2021

One strain-many compounds (OSMAC) manipulation of the sponge-derived fungus Pestalotiopsis heterocornis XWS03F09 resulted in the production of new secondary metabolites. The chemical study of the fermentation, cultivated on 3% artificial sea salt in the rice media, led to the isolation of twelve compounds, including eight new polyketide derivatives, heterocornols Q–X (1–8), one new ceramide (9), and three known analogues (10–12). The structures and absolute configurations of the new compounds were elucidated by spectroscopic data and calculated ECD analysis. Heterocornols Q (1) and R (2) are novel 6/5/7/5 tetracyclic polyketide derivatives featuring dihydroisobenzofuran and benzo-fused dioxabicyclo [4.2.1] nonane system, which might be derived from the acetyl-CoA by epoxidation, polyene cyclization, and rearrangement to form the core skeleton. Compound 12 showed moderate or weak antimicrobial activities against with MIC values ranging from 25 to 100 μg/mL. Heterocornols T and X (7 and 8) could inhibit the production of LPS-induced NO significantly, comparable to dexamethasone. Further Western blotting analysis showed 7 and 8 markedly suppressed the iNOS protein expression in LPS-induced RAW 264.7 cells in a dose-dependent manner. The result showed that 7 and 8 might serve as potential leads for development of anti-inflammatory activity.
Wear Dry Behavior of the Al-6061-Al2O3 Composite Synthesized by Mechanical Alloying
Authors: Mercado-Lemus Víctor , Gomez-Esparza Cynthia , Díaz-Guillén Juan , Mayén-Chaires Jan , Gallegos-Melgar Adriana , Arcos-Gutierrez Hugo , Hernández-Hernández Maricruz , Garduño Isaías , Betancourt-Cantera José , Perez-Bustamante Raúl
Published: October 2021

The present research deals with the comparative wear behavior of a mechanically milled Al-6061 alloy and the same alloy reinforced with 5 wt.% of Al2O3 nanoparticles (Al-6061-Al2O3) under different dry sliding conditions. For this purpose, an aluminum-silicon-based material was synthesized by high-energy mechanical alloying, cold consolidated, and sintered under pressureless and vacuum conditions. The mechanical behavior was evaluated by sliding wear and microhardness tests. The structural characterization was carried out by X-ray diffraction and scanning electron microscopy. Results showed a clear wear resistance improvement in the aluminum matrix composite (Al-6061-Al2O3) in comparison with the Al-6061 alloy since nanoparticles act as a third hard body against wear. This behavior is attributed to the significant increment in hardness on the reinforced material, whose strengthening mechanisms mainly lie in a nanometric size and homogeneous dispersion of particles offering an effective load transfer from the matrix to the reinforcement. Discussion of the wear performance was in terms of a protective thin film oxide formation, where protective behavior decreases as a function of the sliding speed.