bluuebunny/crossref_metadata_2025 huggingface dataset:
High Responsivity Thermopile Sensors Featuring a Mosaic Structure
Authors: Moisello Elisabetta , Castagna Maria Eloisa , La Malfa Antonella , Bruno Giuseppe , Malcovati Piero , Bonizzoni Edoardo
Published: June 2022

This paper presents a detailed analysis of a micromachined thermopile detector featuring high responsivity and a versatile mosaic structure, based on 128 60 µm × 60 µm pixels connected in series and/or in parallel. The mosaic structure is based on the one employed for the thermal sensor known as TMOS, which consists of a CMOS-SOI transistor embedded in a suspended and thermally isolated absorbing membrane, released through microelectro mechanical system (MEMS) post-processing. Two versions of the thermopile detector, featuring different series/parallel connections, are presented and were experimentally characterized. The most performant of the two achieved 2.7 × 104 V/W responsivity. The thermopile sensors’ performances are compared to that of the TMOS sensor, adopting different configurations, and their application as proximity detectors was verified through measurements.
Multi-Scale Structure and Directional Hydrophobicity of Titanium Alloy Surface Using Electrical Discharge
Authors: Wang Mengjie , Peng Zilong , Li Chi , Zhang Junyuan , Wu Jinyin , Wang Fei , Li Yinan , Lan Hongbo
Published: June 2022

Titanium alloys with special macro-micro composite structures of directional hydrophobicity are difficult to prepare due to poor thermal conductivity and good corrosion resistance, inhibiting the wide engineering applications for aerospace, marine engineering, and biomedicine. To prepare macro-micro composite structures on the surface of titanium alloys and achieve directional hydrophobicity, the sub-millimeter structures with an edge width of 150 μm, a groove width of 250 μm, and a depth of 250 μm were fabricated on the titanium alloy by wire electrical discharge machining (WEDM) technology, and high voltage-induced weak electric arc machining (HV-μEAM) was used to fabricate micro-scale feature size micro-structures on the processed macro-structure edges. The influence of process parameters on the morphology of microstructures was studied experimentally. The smooth surface of the titanium alloy is isotropically hydrophilic, and its contact angle is 68°. After processing the macrostructure on the titanium alloy surface, it shows directional hydrophobicity after being modified by low surface energy materials. The macro-micro composite structure formed by HV-μEAM realizes a directional hydrophobic surface with contact angles (CA) of 140° (parallel direction) and 130° (perpendicular direction), respectively. This surface has been modified with low surface energy to achieve contact angles of 154° and 143°. The results of the abrasion resistance test show that under the load of 100 g, it retains directional hydrophobicity at a friction distance of 700 mm with 600# sandpaper. The existence of the sub-millimeter macrostructure is the reason for the directionality of surface hydrophobicity. The microstructure can realize the transformation of the titanium alloy surface from hydrophilic to hydrophobic. Under the combined effects of the macro and micro composite structure, the surface of the titanium alloy shows obvious directional hydrophobicity.
Thiourea-Isocyanate-Based Covalent Organic Frameworks with Tunable Surface Charge and Surface Area for Methylene Blue and Methyl Orange Removal from Aqueous Media
Authors: Suner Selin S. , Demirci Sahin , Sutekin Duygu S. , Yilmaz Selehattin , Sahiner Nurettin
Published: June 2022

A thiourea hexamethylene diisocyanate covalent organic framework (TH COF) was synthesized by adjusting the surface charge and surface area. The surface charge value of TH COF, −3.8 ± 0.5 mV, can be changed to −29.1 ± 0.4 mV by treatment with NaOH (dp-TH) and 17.1 ± 1.0 mV by treatment with HCl (p-TH). Additionally, the surface area of TH COF was 39.3 m2/g, whereas the surface area of dp-TH COF and p-TH COF structures were measured as 41.4 m2/g and 42.5 m2/g, respectively. However, the COF structure had a better adsorption capability with acid and base treatments, e.g., dp-TH COF absorbed 5.5 ± 0.3 mg/g methylene blue (MB) dye, and p-TH COF absorbed 25.9 ± 1.4 mg/g methyl orange (MO) dye from 100 mL 25 ppm aqueous dye solutions, thereby increasing the MB and MO absorption amounts of the TH COF structure. Furthermore, by calculating the distribution, selectivity, and relative selectivity coefficients, the absorption capacity order was determined as dp-TH > TH > p-TH COFs for the MB dye, whereas it was p-TH > TH > dp-TH COFs for the MO dye. Finally, the reusability of dp-TH COF for MB absorption and p-TH COF for MO absorption were investigated. After five repeated uses, dp-TH COF retained 64.6 ± 3.7% of its absorption ability, whereas p-TH COF preserved 79.7 ± 3.2% of its absorption ability relative to the initial absorption amount.
Can Corrole Dimers Be Good Photosensitizers to Kill Bacteria?
Authors: Lacerda Paula S. S. , Bartolomeu Maria , Gomes Ana T. P. C. , Duarte Ana S. , Almeida Adelaide , Faustino Maria A. F. , Neves Maria G. P. M. S. , Barata Joana F. B.
Published: June 2022

Corroles possess key photophysical and photochemical properties to be exploited as therapeutic agents in antimicrobial photodynamic therapy (aPDT). Herein, we present for the first time the antimicrobial efficiency of three corrole dimers and of the corresponding precursor against the Gram(+) bacterium Staphylococcus aureus. Additionally, to explore future clinical applications, the cytotoxicity of the most promising derivatives towards Vero cells was evaluated. The aPDT assays performed under white light irradiation (50 mW/cm2; light dose 450 J/cm2) and at a corrole concentration of 15 µM showed that some dimers were able to reduce 99.9999% of S. aureus strain (decrease of 5 log10 CFU/mL) and their photodynamic efficiency was dependent on position, type of linkage, and aggregation behavior. Under the same light conditions, the corrole precursor 1 demonstrated notable photodynamic efficiency, achieving total photoinactivation (>8.0 log10 CFU/mL reduction) after the same period of irradiation (light dose 450 J/cm2). No cytotoxicity was observed when Vero cells were exposed to corrole 1 and dimer 3 for 24 h according to ISO guidelines (ISO 10993-5) for in vitro cytotoxicity of medical devices. The results show that corrole dimers, dependent on their structures, can be considered good photosensitizers to kill Staphylococcus aureus.
Genome Sequence and Characterization of a Xanthorhodopsin-Containing, Aerobic Anoxygenic Phototrophic Rhodobacter Species, Isolated from Mesophilic Conditions at Yellowstone National Park
Authors: Kyndt John A. , Robertson Sydney , Shoffstall Isabella B. , Ramaley Robert F. , Meyer Terrance E.
Published: June 2022

The genus Rhodobacter consists of purple nonsulfur photosynthetic alphaproteobacteria known for their diverse metabolic capabilities. Here, we report the genome sequence and initial characterization of a novel Rhodobacter species, strain M37P, isolated from Mushroom hot spring runoff in Yellowstone National Park at 37 °C. Genome-based analyses and initial growth characteristics helped to define the differentiating characteristics of this species and identified it as an aerobic anoxygenic phototroph (AAP). This is the first AAP identified in the genus Rhodobacter. Strain M37P has a pinkish-red pigmentation that is present under aerobic dark conditions but disappears under light incubation. Whole genome-based analysis and average nucleotide identity (ANI) comparison indicate that strain M37P belongs to a specific clade of recently identified species that are genetically and physiologically unique from other representative Rhodobacter species. The genome encodes a unique xanthorhodopsin, not found in any other Rhodobacter species, which may be responsible for the pinkish-red pigmentation. These analyses indicates that strain M37P is a unique species that is well-adapted to optimized growth in the Yellowstone hot spring runoff, for which we propose the name Rhodobacter calidifons sp. nov.
Changes of the Freshwater Microbial Community Structure and Assembly Processes during Different Sample Storage Conditions
Authors: Wang Yunfeng , Li Xinghao , Chi Yong , Song Weibo , Yan Qingyun , Huang Jie
Published: June 2022

A long-standing dilemma for microbial analyses is how to handle and store samples, as it is widely assumed that the microbial diversity and community patterns would be affected by sample storage conditions. However, it is quite challenging to maintain consistency in field sampling, especially for water sample collection and storage. To obtain a comprehensive understanding of how sample storage conditions impact microbial community analyses and the magnitude of the potential storage effects, freshwater samples were collected and stored in bottles with lid closed and without lid at room temperature for up to 6 days. We revealed the dynamics of prokaryotic and eukaryotic microbial communities under different storage conditions over time. The eukaryotic microbial communities changed at a faster rate than the prokaryotic microbial communities during storage. The alpha diversity of the eukaryotic microbial communities was not substantially influenced by container status or storage time for up to 12 h, but the beta diversity differed significantly between the control and all treatment samples. By contrast, no significant changes of either the alpha or beta diversity of the prokaryotic microbial communities were observed within 12 h of room-temperature storage, regardless of the container status. The potential interactions between microbial taxa were more complex when samples were stored in sealed bottles, and the deterministic processes played an increasingly important role in shaping the freshwater microbial communities with storage time. Our results suggest that water samples collected and stored without refrigeration for no more than 12 h may still be useful for downstream analyses of prokaryotic microbial communities. If the eukaryotic microbial communities are desired, storage of water samples should be limited to 3 h at room temperature.
Targeting the Gut Microbiota and Host Immunity with a Bacilli-Species Probiotic during Antibiotic Exposure in Mice
Authors: Shapiro David , Kapourchali Fatemeh Ramezani , Santilli Anthony , Han Yingchun , Cresci Gail A. M.
Published: June 2022

Antibiotic therapy is necessary for the treatment of bacterial infections; however, it can also disrupt the balance and function of commensal gut microbes and negatively affect the host. Probiotics have been tested as a means to counteract the negative effects of antibiotic therapy, but many probiotics are also likely destroyed by antibiotics when taken together. Here we aimed to test the efficacy of a non-pathogenic spore-forming Bacillus-species containing a probiotic blend provided during antibiotic therapy on host immune defenses in mice. Mice were exposed to antibiotics and supplemented with or without the probiotic blend and compared to control mice. Fecal and cecal contents were analyzed for gut microbes, and intestinal tissue was tested for the expression of key enzymes involved in vitamin A metabolism, serum amyloid A, and inflammatory markers in the intestine. The probiotic blend protected against antibiotic-induced overgrowth of gram-negative bacteria and gammaproteobacteria in the cecum which correlated with host immune responses. Regional responses in mRNA expression of enzymes involved with vitamin A metabolism occurred between antibiotic groups, and intestinal inflammatory markers were mitigated with the probiotic blend. These data suggest prophylactic supplementation with a spore-forming Bacillus-containing probiotic may protect against antibiotic-induced dysregulation of host immune responses.
Variations in Marine Bacterial and Archaeal Communities during an Ulva prolifera Green Tide in Coastal Qingdao Areas
Authors: Zhao Guihua , He Hui , Wang Hualong , Liang Yantao , Guo Cui , Shao Hongbing , Jiang Yong , Wang Min
Published: June 2022

Green tides caused by Ulva prolifera occur annually in the Yellow Sea, potentially influencing the marine microorganisms. Here, we focused on the variations in marine bacterial and archaeal communities during an U. prolifera green tide in coastal Qingdao areas with Illumina high-throughput sequencing analysis. Our results revealed that the diversity and structure of bacterial and archaeal communities, as well as the organization and structure of microbial co-occurrence networks, varied during the green tide. The decline phase may be favorable to the bacterial and archaeal diversity and richness. The bacterial community, as well as the archaeal community, showed clear variations between the outbreak and decline phases. A simpler and less connected microbial co-occurrence network was observed during the outbreak phase compared with the decline phase. Flavobacteriales and Rhodobacterales separately dominated the bacterial community during the outbreak and decline phase, and Marine Group II (MGII) dominated the archaeal community during the green tide. Combined with microbial co-occurrence network analysis, Flavobacteriales, Rhodobacterales and MGII may be important organisms during the green tide. Temperature, chlorophyll a content and salinity may have an important impact on the variations in bacterial and archaeal communities during the green tide.
Nature and Isomorphism of Extra-Framework Components in Cancrinite- and Sodalite-Related Minerals: New Data
Authors: Chukanov Nikita V. , Vigasina Marina F. , Shendrik Roman Yu. , Varlamov Dmitry A. , Pekov Igor V. , Zubkova Natalia V.
Published: June 2022

New data on the isomorphism of extra-framework components (including chromophores) in two- and multilayer minerals belonging to the cancrinite and sodalite groups, are obtained using chemical and single-crystal X-ray diffraction data as well as infrared, Raman, ESR, UV–Vis–near IR absorption and photoluminescence spectroscopy methods. It is shown that the blue color of these minerals may be due to CO3•− or S3•− radical anions, whereas yellow and pink shadings are typically due to the presence of S2•− radical anions and S4•− or S4, respectively. Two kyanoxalite varieties are distinguished: (1) with predominantly acid oxalate groups and (2) predominantly neutral oxalate groups. Zundel cation H5O2+ and CO2 molecules are shown to be typical impurities in nosean. The Zundel cation is also detected in kyanoxalite and in the 12-layer, cancrinite-related mineral marinellite. Wide isomorphic series involving substitutions of SO4− for SO32− and CO32−, as well as OH− for H2O and F−, are common for eight-layer, cancrinite-group minerals with an afghanite-type framework.
The Effect of Different Outer Cations on the Stability of Fluorotitanium Complex
Authors: Liu Junfeng , Zuo Xugang , Liu Haotian
Published: June 2022

Fluoride-rich fluid is believed to be able to activate and migrate Ti and other high field-strength elements to the greatest extent. The stability of F-rich titanium complexes can ensure their migration in the fluid, but is inseparable from the physical and chemical properties of the fluid, such as concentration, temperature and pH value—important factors affecting the stability of the complexes. In this study, the influence of the outer cationic complex fluid on the stability of the fluorine titanium complex was studied. Studies were based on different kinds of fluorine titanium complex (K2TiF6, Na2TiF6, (NH4)2TiF6 and H2TiF6) in 100 MPa pressure. Under the condition of 200~500 °C temperature, we found that as the temperature rises, the hydrolysis of F-rich titanium complexes is violent. We compared the stability of four F-titanium complexes with different outer cations according to the hydrolysis rate and the cumulative hydrolysis equilibrium constant. We compared the F-titanium complexes with alkali metal as the outer cations that are more stable, such as K2TiF6 and Na2TiF6. However, the F-rich titanium complex in an acidic fluid is relatively unstable, which is not conducive to the migration of Ti elements. Due to the water–rock reactions that occur in hydrothermal fluid migration, mixing and alteration, once in the hydrothermal system, the fluid composition, pH value and temperature change. Thus, the F-titanium complex becomes extremely unstable, leading to the precipitation of titanium from the hydrothermal fluid and the growth of Ti-rich minerals.
Control Structure Design Using Global Sensitivity Analysis for Mineral Processes under Uncertainties
Authors: Mamani-Quiñonez Oscar , Cisternas Luis A. , Lopez-Arenas Teresa , Lucay Freddy A.
Published: June 2022

Multiple-input and multiple-output (MIMO) systems can be found in many industrial processes, including mining processes. In practice, these systems are difficult to control due to the interactions of their input variables and the inherent uncertainty of industrial processes. Depending on the interactions in the MIMO process, different control strategies can be implemented to achieve the desired performance. Among these strategies is the use of a decentralized structure that considers several subsystems and for which a SISO controller can be designed. In this study, a methodology based on global sensitivity analysis (GSA) to design decentralized control structures for industrial processes under uncertainty is presented. GSA has not yet been applied for this purpose in process control; it allows us to understand the dynamic behavior of systems under uncertainty in a broad value range, unlike approaches proposed in the literature. The proposed GSA is based on the Sobol method, which provides sensitivity indices used as interaction measures to establish the input–output pairing for MIMO systems. Two case studies based on a semi-autogenous grinding (SAG) mill and a solvent extraction (SX) plant are presented to demonstrate the applicability of the proposed methodology. The results indicate that the methodology allows the design of 2 × 2 and 3 × 3 decentralized control structures for the SAG mill and SX plant, respectively, which exhibit good performance compared to MPC. For example, for the SAG mill, the determined pairings were fresh ore flux/fraction of mill filling and power consumption/percentage of critical speed.
Knothe Time Function Optimization Model and Its Parameter Calculation Method and Precision Analysis
Authors: Hu Qingfeng , Cui Ximin , Liu Wenkai , Feng Ruimin , Ma Tangjing , Yuan Debao
Published: June 2022

Considering the shortcomings of the currently used time functions for dynamically predicting surface mining subsidence and calculating its parameters, a novel time function is proposed on the basis of an in-depth analysis on the movement characteristics of mining surface points in a fully mined area and the measured mining subsidence data in the field during the course of the mining process. The proposed function can be used to effectively characterize the surface subsidence, the subsidence velocity, and the acceleration of the mining area. All the parameters involved in the function have their physical meaning, and their influence on the function was also analyzed in this study. A parameter calculation method is proposed for the new time function based on the normalization method and least square principle. Taking the measured dynamic subsidence data of 22,618 working faces in a coal mine as an example, the reliability of the new time function model was verified by comparing the measured data with the predicted results. The results show that the average relative root-mean-square error was 5.2%, and the prediction accuracy was improved compared with the Knothe time function, double-parameter Knothe time function, and piecewise optimized Knothe time function.
Analytical Approach Based on Full-Space Synergy Technology to Optimization Support Design of Deep Mining Roadway
Authors: Zhang Shike , Yin Shunde
Published: June 2022

The stability of surrounding rock is the basic guarantee of underground space engineering safety. The large deformation of a roadway’s surrounding rock is a very common phenomenon during the underground excavation of coal mine roadways or coal mining, especially in deep soft rock mining roadways. With the increase in mining depth and mining stress, it is very important to prevent disasters caused by surrounding rock deformation. This work aims to conduct an optimization design of roadway support for deep soft rock in coal mines using a full-space synergy control technology. FLAC3D-based orthogonal numerical experiments are adopted to study the influence of bolt parameters and plastic yield zone variation on the deformation of roadway surrounding rock, which provides a basis for optimizing the support design of coal mine roadways. According to the results of the numerical analysis, the optimal support parameters are determined as 20 mm, 2.2 m and 700–900 mm for diameter, length and interval of the bolt, respectively. Finally, the determined bolt-shotcrete net beam support scheme from the full-space synergy control idea is used in a study case. Results illustrate that this study can provide reliable guidance for the stability control of deep soft rock roadways in mining fields under high stress, and it can work well to keep the surrounding rock deformation within the safe limits.
In Vitro High-Throughput Toxicological Assessment of Nanoplastics
Authors: Tolardo Valentina , Magrì Davide , Fumagalli Francesco , Cassano Domenico , Athanassiou Athanassia , Fragouli Despina , Gioria Sabrina
Published: June 2022

Sub-micrometer particles derived from the fragmentation of plastics in the environment can enter the food chain and reach humans, posing significant health risks. To date, there is a lack of adequate toxicological assessment of the effects of nanoplastics (NPs) in mammalian systems, particularly in humans. In this work, we evaluated the potential toxic effects of three different NPs in vitro: two NPs obtained by laser ablation (polycarbonate (PC) and polyethylene terephthalate (PET1)) and one (PET2) produced by nanoprecipitation. The physicochemical characterization of the NPs showed a smaller size, a larger size distribution, and a higher degree of surface oxidation for the particles produced by laser ablation. Toxicological evaluation performed on human cell line models (HePG2 and Caco-2) showed a higher toxic effect for the particles synthesized by laser ablation, with PC more toxic than PET. Interestingly, on differentiated Caco-2 cells, a conventional intestinal barrier model, none of the NPs produced toxic effects. This work wants to contribute to increase knowledge on the potential risks posed by NPs.
Study of the Interaction of Ti–Zn as a Mixed Oxide at Different pH Values Synthesized by the Sol–Gel Method and Its Antibacterial Properties
Authors: Rodríguez-Barajas Noé , Becerra-Solano Luis , Gutiérrez-Mercado Yanet Karina , Macías-Carballo Monserrat , M. Gómez Claudia , Pérez-Larios Alejandro
Published: June 2022

TiO2, ZnO, and their combination (TiO2–ZnO) at different molar ratios and pH values (Ti–Zn A and B 3:1, 1:1, and 1:3) via the sol–gel method were characterized by SEM, XRD, UV-Vis, and FT-IR. Moreover, antibacterial tests of the nanoparticles were conducted against Escherichia coli (E. coli), Salmonella paratyphi (S. paratyphi), Staphylococcus aureus (S. aureus), and Listeria monocytogenes (L. monocytogenes). The indirect bandgap of the Ti–Zn binary oxide synthesized in the basic process at molar ratios of 3:1, 1:1, and 1:3 exhibited a higher eV (3.31, 3.30, and 3.19 eV, respectively) compared to pure TiO2 (3.2 eV) and synthesized in the acid process (3.22, 3.29, and 3.19 eV at same molar ratio, respectively); in addition, the results of the indirect bandgap were interesting due to a difference found by other authors. Moreover, the sol–gel method promoted the formation of a spherical, semi-sphere, and semi-hexagonal shape (TiO2, Ti–Zn 1:1, and Ti–Zn 1:3) with a size ≤ 150 nm synthesized during the acid process, with a crystallite size of ~71, ~12, ~34, and ~21 nm, respectively, while ZnO NPs developed a hexagonal and large size (200–800 nm) under the same synthesis process (acid). Samples were classified as TiO2 anatase phase (basic synthesis); however, the presented changes developed in the rutile phase (24% rutile phase) at an acid pH during the synthesis process. Moreover, Ti–Zn maintained the anatase phase even with a molar ratio of 1:3. The most interesting assessment was the antibacterial test; the Ti–Zn A (1:3) demonstrated a bacteriostatic effect compared with all treatments except ZnO, which showed a similar effect in dark conditions, and only Gram-positive bacteria were susceptible (Listeria monocytogenes > Staphylococcus aureus). Therefore, the Ti–Zn characteristic suggests that the results have potential in treating wastewater as well as in pharmaceutical (as drug carriers) and medical applications.
Enhanced Antibacterial Activity through Silver Nanoparticles Deposited onto Carboxylated Graphene Oxide Surface
Authors: Barjola Arturo , Tormo-Mas María Ángeles , Sahuquillo Oscar , Bernabé-Quispe Patricia , Pérez José Manuel , Giménez Enrique
Published: June 2022

The strong bactericidal action of silver nanoparticles (AgNPs) is usually limited by their degree of aggregation. Deposition of AgNPs onto a graphene oxide (GO) surface to generate GO-Ag hybrids has been shown to be an effective method of controlling these aggregation problems. In this sense, a novel carboxylated graphene oxide–silver nanoparticle (GOCOOH-Ag) material has been synthesized, and their antibacterial and biofilm formation inhibitions have been studied. AgNPs decorating the GOCOOH surface achieved an average size of 6.74 ± 0.25 nm, which was smaller than that of AgNPs deposited onto the GO surface. In addition, better distribution of AgNPs was achieved using carboxylated material. It is important to highlight the main role of the carboxylic groups in the nucleation and growth of the AgNPs that decorate the GO-based material surface. In vitro antibacterial activity and antibiofilm-forming action were tested against Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Both GO-Ag and GOCOOH-Ag reduced bacterial growth, analyzed by time–kill curves. However, the minimum inhibitory concentration and the minimum bactericidal concentration of GOCOOH-Ag were lower than those of GO-Ag for all strains studied, indicating that GOCOOH-Ag has better antibacterial activity. In addition, both nanomaterials prevent biofilm formation, with a higher reduction of biofilm mass and cell viability in the presence of GOCOOH-Ag. The carboxylation functionalization in GO-based materials can be applied to improve the bactericidal and antibiofilm-forming action of the AgNPs.
Depth of Cure, Hardness, Roughness and Filler Dimension of Bulk-Fill Flowable, Conventional Flowable and High-Strength Universal Injectable Composites: An In Vitro Study
Authors: Ludovichetti Francesco Saverio , Lucchi Patrizia , Zambon Giulia , Pezzato Luca , Bertolini Rachele , Zerman Nicoletta , Stellini Edoardo , Mazzoleni Sergio
Published: June 2022

(1) Objective: To evaluate and compare the depth of cure (DOC) of two bulk-fill flowable composites (Filtek Bulk Fill Flowable Restorative and Tetric EvoFlow Bulk Fill), two conventional flowable composites (Filtek Supreme XTE Flowable Restorative and G-ænial Flo X) and one high-strength universal injectable composite (G-ænial Universal Injectable). (2) Methods: specimens were placed in a stainless-steel mold with an orifice of 4 mm in diameter and 10 mm in depth and light-cured for 20 s using a light emitting diode (LED) light-curing unit (LCU) with an irradiance of 1000 mW/cm2; depth of cure was assessed using the ISO 4049 scrape technique, and the absolute length of the specimen of cured composite was measured in millimeters with a digital caliper. The same procedure was repeated with 14 samples for each material under investigation, for a total number of 70 test bodies. Material roughness and hardness results were also investigated using, respectively, a 3D laser confocal microscope (LEXT OLS 4100; Olympus) at ×5 magnification and a Vickers diamond indenter (Vickers microhardness tester, Shimadzu®, Kyoto, Japan) under 10-N load and a 30 s dwell time. SEM images at 3000 and 9000 magnification were collected in order to study the materials’ filler content. Statistical analysis were performed by a commercial statistical software package (SPSS) and data were analyzed using multiple comparison Dunnett’s test. (3) Results: The average DOC of both bulk-fill composites was more than 4 mm, as a range of 3.91 and 4.53 mm with an average value of 4.24 and 4.12 mm, while that of the conventional flowable composites was much lower, as a range of 2.47 and 2.90 mm with an average value of 2.58 and 2.84 mm; DOC of the high-strength injectable composite was greater than the one of traditional composites, but not to the level of bulk-fill materials, as a range of 2.82 and 3.01 mm with an average value of 3.02 mm. Statistical analysis revealed significant differences (p-values < 0.05) in the depth of cure between bulk fill flowable composites and other composites, while there was no difference (p-values > 0.05) between the materials of the same type. (4) Conclusions: Bulk-fill flowable composites showed significantly higher depth of cure values than both traditional flowable composites and high-strength injectable composites.
Simple Synthesis and Characterization of Shell-Thickness-Controlled Ni/Ni3C Core-Shell Nanoparticles
Authors: Kim Sun-Woo , Ro Jae Chul , Suh Su-Jeong
Published: June 2022

Ni/Ni3C core-shell nanoparticles with an average diameter of approximately 120 nm were carburized via a chemical solution method using triethylene glycol. It was found that over time, the nanoparticles were covered with a thin Ni3C shell measuring approximately 1–4 nm, and each Ni core was composed of poly grains. The saturation magnetization of the core-shell nanopowders decreased in proportion to the amount of Ni3C. The synthesis mechanism of the Ni/Ni3C core-shell nanoparticles was proposed through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses.
Solar Cell Parameter Extraction Method from Illumination and Dark I-V Characteristics
Authors: Montalvo-Galicia Fredy , Sanz-Pascual María Teresa , Rosales-Quintero Pedro , Moreno-Moreno Mario
Published: June 2022

A novel method to extract the seven parameters of the double-diode model of solar cells using the current–voltage (I-V) characteristics under illumination and in the dark is presented. The algorithm consists of two subroutines which are alternatively run to adjust all the parameters of the cell in an iterative process. Curve fitting of the light I-V characteristics ensures accuracy in the prediction of the maximum power point, whereas simultaneously fitting the dark I-V characteristics results in a set of physically meaningful parameters that provide information about the physical performance of the photovoltaic devices. Experimental I-V curves of in-house solar cells are used to validate the proposed parameter extraction method, which can be furthermore applied to other types of p–n junction-based photovoltaic devices.
Advances in Engineered Metal Oxide Thin Films by Low-Cost, Solution-Based Techniques for Green Hydrogen Production
Authors: Rodríguez-Gutiérrez Ingrid , Bedin Karen Cristina , Mouriño Beatriz , Souza Junior João Batista , Souza Flavio Leandro
Published: June 2022

Functional oxide materials have become crucial in the continuous development of various fields, including those for energy applications. In this aspect, the synthesis of nanomaterials for low-cost green hydrogen production represents a huge challenge that needs to be overcome to move toward the next generation of efficient systems and devices. This perspective presents a critical assessment of hydrothermal and polymeric precursor methods as potential approaches to designing photoelectrodes for future industrial implementation. The main conditions that can affect the photoanode’s physical and chemical characteristics, such as morphology, particle size, defects chemistry, dimensionality, and crystal orientation, and how they influence the photoelectrochemical performance are highlighted in this report. Strategies to tune and engineer photoelectrode and an outlook for developing efficient solar-to-hydrogen conversion using an inexpensive and stable material will also be addressed.
Interaction Mechanisms and Application of Ozone Micro/Nanobubbles and Nanoparticles: A Review and Perspective
Authors: Xiao Wei , Zhang He , Wang Xiaohuan , Wang Biao , Long Tao , Deng Sha , Yang Wei
Published: June 2022

Ozone micro/nanobubbles with catalytic processes are widely used in the treatment of refractory organic wastewater. Micro/nanobubble technology overcomes the limitations of ozone mass transfer and ozone utilization in the application of ozone oxidation, and effectively improves the oxidation efficiency of ozone. The presence of micro/nanobubbles keeps the catalyst particles in a dynamic discrete state, which effectively increases the contact frequency between the catalyst and refractory organic matter and greatly improves the mineralization efficiency of refractory organic matter. This paper expounds on the characteristics and advantages of micro/nanobubble technology and summarizes the synergistic mechanism of microbubble nanoparticles and the mechanism of catalyst ozone micro/nanobubble systems in the treatment of refractory organics. An interaction mechanism of nanoparticles and ozone microbubbles is suggested, and the proposed theories on ozone microbubble systems are discussed with suggestions for future studies on systems of nanoparticles and ozone microbubbles.
Scanning Deposition Method for Large-Area Diamond Film Synthesis Using Multiple Microwave Plasma Sources
Authors: Hong Seung Pyo , Lee Kang-il , You Hyun Jong , Jang Soo Ouk , Choi Young Sup
Published: June 2022

The demand for synthetic diamonds and research on their use in next-generation semiconductor devices have recently increased. Microwave plasma chemical vapor deposition (MPCVD) is considered one of the most promising techniques for the mass production of large-sized and high-quality single-, micro- and nanocrystalline diamond films. Although the low-pressure resonant cavity MPCVD method can synthesize high-quality diamonds, improvements are needed in terms of the resulting area. In this study, a large-area diamond synthesis method was developed by arranging several point plasma sources capable of processing a small area and scanning a wafer. A unit combination of three plasma sources afforded a diamond film thickness uniformity of ±6.25% at a wafer width of 70 mm with a power of 700 W for each plasma source. Even distribution of the diamond grains in a size range of 0.1–1 μm on the thin-film surface was verified using field-emission scanning electron microscopy. Therefore, the proposed novel diamond synthesis method can be theoretically expanded to achieve large-area films.
Experimental Investigation of Thermal Conductivity of Water-Based Fe3O4 Nanofluid: An Effect of Ultrasonication Time
Authors: Barai Divya P. , Bhanvase Bharat A. , Żyła Gaweł
Published: June 2022

Nanofluid preparation is a crucial step in view of their thermophysical properties as well as the intended application. This work investigates the influence of ultrasonication duration on the thermal conductivity of Fe3O4 nanofluid. In this work, water-based Fe3O4 nanofluids of various volume concentrations (0.01 and 0.025 vol.%) were prepared and the effect of ultrasonication time (10 to 55 min) on their thermal conductivity was investigated. Ultrasonication, up to a time duration of 40 min, was found to raise the thermal conductivity of Fe3O4 nanofluids, after which it starts to deteriorate. For a nanofluid with a concentration of 0.025 vol.%, the thermal conductivity increased to 0.782 W m−1K−1 from 0.717 W m−1K−1 as the ultrasonication time increased from 10 min to 40 min; however, it further deteriorated to 0.745 W m−1K−1 after a further 15 min increase (up to a total of 55 min) in ultrasonication duration. Thermal conductivity is a strong function of concentration of the nanofluid; however, the optimum ultrasonication time is the same for different nanofluid concentrations.
Feasibility of Silicon Quantum Dots as a Biomarker for the Bioimaging of Tear Film
Authors: Sarwat Sidra , Stapleton Fiona Jane , Willcox Mark Duncan Perry , O’Mara Peter B. , Tilley Richard David , Gooding J. Justin , Roy Maitreyee
Published: June 2022

This study investigated the fluorescence and biocompatibility of hydrophilic silicon quantum dots (SiQDs) that are doped with scandium (Sc-SiQDs), copper (Cu-SiQDs), and zinc (Zn-SiQDs), indicating their feasibility for the bioimaging of tear film. SiQDs were investigated for fluorescence emission by the in vitro imaging of artificial tears (TheraTears®), using an optical imaging system. A trypan blue exclusion test and MTT assay were used to evaluate the cytotoxicity of SiQDs to cultured human corneal epithelial cells. No difference was observed between the fluorescence emission of Sc-SiQDs and Cu-SiQDs at any concentration. On average, SiQDs showed stable fluorescence, while Sc-SiQDs and Cu-SiQDs showed brighter fluorescence emissions than Zn-SiQDs. Cu-SiQDs and Sc-SiQDs showed a broader safe concentration range than Zn-SiQDs. Cu-SiQDs and Zn-SiQDs tend to aggregate more substantially in TheraTears® than Sc-SiQDs. This study elucidates the feasibility of hydrophilic Sc-SiQDs in studying the tear film’s aqueous layer.
First-Principles Study of n*AlN/n*ScN Superlattices with High Dielectric Capacity for Energy Storage
Authors: Zhang Wei-Chao , Wu Hao , Sun Wei-Feng , Zhang Zhen-Peng
Published: June 2022

As a paradigm of exploiting electronic-structure engineering on semiconductor superlattices to develop advanced dielectric film materials with high electrical energy storage, the n*AlN/n*ScN superlattices are systematically investigated by first-principles calculations of structural stability, band structure and dielectric polarizability. Electrical energy storage density is evaluated by dielectric permittivity under a high electric field approaching the uppermost critical value determined by a superlattice band gap, which hinges on the constituent layer thickness and crystallographic orientation of superlattices. It is demonstrated that the constituent layer thickness as indicated by larger n and superlattice orientations as in (111) crystallographic plane can be effectively exploited to modify dielectric permittivity and band gap, respectively, and thus promote energy density of electric capacitors. Simultaneously increasing the thicknesses of individual constituent layers maintains adequate band gaps while slightly reducing dielectric polarizability from electronic localization of valence band-edge in ScN constituent layers. The AlN/ScN superlattices oriented in the wurtzite (111) plane acquire higher dielectric energy density due to the significant improvement in electronic band gaps. The present study renders a framework for modifying the band gap and dielectric properties to acquire high energy storage in semiconductor superlattices.
Experimentally-Verified Modeling of InGaAs Quantum Dots
Authors: Kosarev Alexander N. , Chaldyshev Vladimir V. , Cherkashin Nikolay
Published: June 2022

We develop a model of an epitaxial self-organized InGaAs quantum dot buried in GaAs, which takes into account experimentally determined indium distribution inside the QD, its geometry and crystallography. The problem of solid mechanics was solved to determine the stress-strain field. Then, the parameters of the electron and hole ground states were evaluated by solving the problem of the quantum mechanics on the same mesh. The results of calculations appeared to be reasonably well consistent with experimentally recorded optical emission spectra for the QDs in the same sample. The experimentally-verified modeling reveals a bagel-like shape of the hole wave function at the ground state, which should considerably impact the optical and magnetic properties of the QDs. Such shape of the wave function is beyond the predictions of simplified models with uniform indium distribution.
Distinguishing Local Demagnetization Contribution to the Magnetization Process in Multisegmented Nanowires
Authors: Marqués-Marchán Jorge , Fernandez-Roldan Jose Angel , Bran Cristina , Puttock Robert , Barton Craig , Moreno Julián A. , Kosel Jürgen , Vazquez Manuel , Kazakova Olga , Chubykalo-Fesenko Oksana , Asenjo Agustina
Published: June 2022

Cylindrical magnetic nanowires are promising materials that have the potential to be used in a wide range of applications. The versatility of these nanostructures is based on the tunability of their magnetic properties, which is achieved by appropriately selecting their composition and morphology. In addition, stochastic behavior has attracted attention in the development of neuromorphic devices relying on probabilistic magnetization switching. Here, we present a study of the magnetization reversal process in multisegmented CoNi/Cu nanowires. Nonstandard 2D magnetic maps, recorded under an in-plane magnetic field, produce datasets that correlate with magnetoresistance measurements and micromagnetic simulations. From this process, the contribution of the individual segments to the demagnetization process can be distinguished. The results show that the magnetization reversal in these nanowires does not occur through a single Barkhausen jump, but rather by multistep switching, as individual CoNi segments in the NW undergo a magnetization reversal. The existence of vortex states is confirmed by their footprint in the magnetoresistance and 2D MFM maps. In addition, the stochasticity of the magnetization reversal is analysed. On the one hand, we observe different switching fields among the segments due to a slight variation in geometrical parameters or magnetic anisotropy. On the other hand, the stochasticity is observed in a series of repetitions of the magnetization reversal processes for the same NW under the same conditions.
Flexible Humidity Sensors Based on Multidimensional Titanium Dioxide/Cellulose Nanocrystals Composite Film
Authors: Tong Xin , Wang Hong , Ding Huiyang , Li Jing , Zhao Huifang , Lin Zhaoyun , Xi Hongxia , Zhang Xuejin
Published: June 2022

A humidity sensor is a crucial device in daily life; therefore, in the present study, a novel humidity sensor was designed to increase its specific surface area to improve its humid sensing capacity and conductivity. Titanium dioxide nanoparticles (TiNP) consisting of zero-dimensional nanospheres and one-dimensional nanotubes were prepared by anodic oxidation. Rod-shaped cellulose nanocrystals (CNCs) with average length and diameter of 60 nm and 800 nm, respectively, were obtained by enzymatic hydrolysis and high pressure homogenization. TiNP/CNC composite films exhibited superior hydrophilicity and large specific surface areas based on Fourier transform infrared spectroscopy and nitrogen adsorption–desorption results. The humidity sensing characteristics of sensors based on TiNP/CNC flexible composite films with varying contents of TiNP were investigated under a relative humidity range of 11–97%. The 6% TiNP/CNC-based humidity sensor exhibited high humidity response, rapid response/recovery speed, and high stability. Furthermore, the humidity sensing mechanism of TiNP/CNC composite films was analyzed based on the density functional theory. TiNP/CNC-based humidity sensors could be applied in flexible and wearable electronics.
Effect of the Addition of Varying Concentrations of Silver Nanoparticles on the Fluoride Uptake and Recharge of Glass Ionomer Cement
Authors: Alshehri Turki D. , Kotha Sunil Babu , Abed Faisal Mohammed , Barry Mohammed J. , AlAsmari Abdulrahman , Mallineni Sreekanth Kumar
Published: June 2022

This study aimed to compare the amount of fluoride uptake and the recharge and release characteristics of conventional glass ionomer cement (GIC) without any additives in comparison to conventional glass ionomer cement supplemented with silver nanoparticles (AgNPs) at two concentrations: 0.1% and 0.2% (w/w). A total of 60 specimens were used in this in vitro study. The sample was divided into six groups—including three groups without fluoride charge: Group 1 (conventional GIC), Group 2 (GIC with 0.1% silver nanoparticles), and Group 3 (GIC with 0.2% silver nanoparticles; and three groups with fluoride charge: Group 4 (conventional GIC with fluoride); Group 5 (GIC with 0.1% silver nanoparticles with fluoride); Group 6 (GIC with 0.2% silver nanoparticles with fluoride), where Group 1 is considered the control group and the other five groups are used as the test groups. The amount of fluoride released was measured on days 1, 2, 7, 15, and 30. The comparisons were made between the groups with and without fluoride and among all the groups. A significant difference in the amount of fluoride released was observed between the groups, with the highest amount occurring in Group 1, followed by Group 2; the lowest amount of fluoride released was observed in Group 3 (p < 0.05). The groups with fluoride recharge (Groups 4, 5, and 6) exhibited a higher amount of fluoride release than the groups with no recharge (Groups 1, 2, and 3); however, Group 1 has more fluoride release compared to all other groups on days 1, 2, 7, 15, and 30 (p < 0.05). The amount of released fluoride decreased from day 1 to day 30 in all of the groups in the study. Despite the antimicrobial and anticariogenic benefits of adding silver nanoparticles to GIC, it seems that fluoride release characteristics are significantly affected by the addition of this material. This may force the clinician to a compromise between the antimicrobial benefit of silver nanoparticles and the remineralizing advantage of fluoride.
Properties of SS304 Modified by Nickel–Cobalt Alloy Coating with Cauliflower-Shaped Micro/Nano Structures in Simulated PEMFC Cathode Environment
Authors: Xuan Junji , Liu Yueren , Xu Likun , Xin Yonglei , Xue Lili , Li Li
Published: June 2022

This study presents the corrosion behavior and surface properties of SS304 modified by electrodeposited nickel–cobalt (Ni–Co) alloy coating with cauliflower-shaped micro/nano structures (Ni–Co/SS304) in the simulated PEMFC cathodic environment. The hydrophobicity of the as-prepared Ni–Co alloy coating can be improved simply by low-temperature annealing. The morphology and composition of the Ni–Co/SS304 were analyzed and characterized by SEM, EDS, XRD, and XPS. The polarization, wettability, and ICR tests were respectively conducted to systemically evaluate the performance of Ni–Co/SS304 in the simulated PEMFC cathode environment. As revealed by the results, the Ni–Co/SS304 can maintain its hydrophobicity under hot-water droplets as high as 80 °C and demonstrates higher conductivity than the bare SS304 substrate before and after polarization (0.6 V vs. SCE, 5 h), which is of great significance to improve the surface hydrophobicity and conductivity of bipolar plates.