bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Grain Size in 316L Stainless Steel Using the Attenuation of Rayleigh Wave Measured by Air-Coupled Transducer
Authors: Wang Meng , Bu Yangguang , Dai Zhaojie , Zeng Shengyang
Published: April 2021

Grain size is an important parameter in evaluating the properties of microstructures in metals. In this paper, the attenuation coefficient of Rayleigh waves is introduced to characterize grain size in heat treated 316L stainless steel. Rayleigh wave attenuation is measured using an angle beam wedge transducer as the transmitter and an air-coupled transducer as the receiver. The results show that the grain size in 316L stainless steel increases due to heat treatment time, the hardness decreases accordingly, and the attenuation coefficient of Rayleigh waves increases. This indicates that the Rayleigh wave attenuation is sufficient in distinguishing the changes in the properties of the heat-treated stainless steel. It is found that compared with the measurement method using an angle beam wedge receiver, the measured results are efficient, more stable and less influenced by the surface state when an air-coupled receiver is used. In addition, comparison results also show that the Rayleigh wave attenuation is more sensitive to changes in material properties than the longitudinal wave attenuation, as the wavelength of the Rayleigh wave is shorter than that of the longitudinal wave at the same frequency.
Selective Laser Melting of Maraging Steel Using Synchronized Three-Spot Scanning Strategies
Authors: Cheng Chung-Wei , Jhang Jian Wei-You , Makala Bhargav Prasad Reddy
Published: April 2021

The selective laser melting (SLM) process, a kind of metal additive manufacturing method, can produce parts with complex geometries that cannot be easily manufactured using material removal processes. With increasing industrial applications, there are still issues such as part quality and productivity that need to be resolved. In this study, maraging steel parts fabricated by synchronized three-spot scanning strategies, i.e., lateral spatial (LS) and spatial inline (SiL), are firstly presented. The LS and SiL represent the three-spot offset direction is perpendicular and parallel to the scanning direction, respectively. A laboratory SLM machine equipped with a fiber laser and three-spot module is used to fabricate the maraging steel parts with two scanning strategies, i.e., LS and SiL. The influence of these scanning strategies on the surface roughness, relative density, hardness, molten pool shapes, and microstructures are investigated. The relative density (~99.02%) and surface hardness (~34.0 HRC) are experimentally found to be higher than the SiL by the LS scanning strategy.
Effect of Thermal Buoyancy on Fluid Flow and Residence-Time Distribution in a Single-Strand Tundish
Authors: Sheng Dong-Yuan , Jönsson Pär G.
Published: April 2021

Natural convection of molten steel flow in a tundish occurs due to the temperature variation of the inlet stream and heat losses through top surface and refractory walls. A computational fluid dynamics (CFD) model was applied to study the effect of thermal buoyancy on fluid flow and residence-time distribution in a single-strand tundish. The CFD model was first validated with the experimental data from a non-isothermal water model and then applied to both scale-down model and prototype. The effects of flow control devices, including weir, dam and turbulence inhibitor, were compared and analyzed. Parameter studies of different heat losses through the top surface were performed. The results show that thermal buoyancy has a significant impact on the flow pattern and temperature distributions of molten steel in the tundish. The increase of heat loss through the top surface shortens the mean residence time of molten steel in the tundish, leading to an increase in dead volume fraction and a decrease in plug flow volume fraction.
Aggregation Induced Emission and Nonlinear Optical Properties of an Intramolecular Charge-Transfer Compound
Authors: Chen Songhua , Luo Rui , Li Xinyue , He Meiyun , Fu Shanshan , Xu Jialiang
Published: April 2021

Intramolecular charge transfer (ICT) compounds have attracted wide attention for their potential applications in optoelectronic materials and devices such as fluorescent sensors, dye-sensitized solar cells, organic light emitting diodes and nonlinear optics. In this work, we have synthesized a new ICT compound, dimethyl-[4-(7-nitro-benzo[1,2,5]thiadiazol-4-yl)-phenyl]-amine (BTN), and have fabricated it into low dimensional micro/nano structures with well-defined morphologies. These self-assembled nanostructures exhibit high efficiency solid state fluorescence via an aggregation induced emission mechanism, which overcomes the defect of fluorescence quenching caused by aggregation in the solid state of traditional luminescent materials. We also explored and studied the nonlinear optical properties of this material through the Z-scan method, and found that this material exhibits large third-order nonlinear absorption and refraction coefficients, which promises applications of the materials in the fields of nonlinear optics and optoelectronics.
Research on Reduction of Selected Iron-Bearing Waste Materials
Authors: Mróz Jan , Konstanciak Anna , Warzecha Marek , Więcek Marcin , Hutny Artur M.
Published: April 2021

During the steel production process, nearly twice as many input materials are used as compared to finished products. This creates a large amount of post-production waste, including slag, dust, and sludge. New iron production technologies enable the reuse and recycling of metallurgical waste. This paper presents an investigation on the reduction of selected iron-bearing waste materials in a laboratory rotary furnace. Iron-bearing waste materials in the form of dust, scale, and sludge were obtained from several Polish metallurgical plants as research material. A chemical analysis made it possible to select samples with sufficiently high iron content for testing. The assumed iron content limit in waste materials was 40 wt.% Fe. A sieve analysis of the samples used in the subsequent stages of the research was also performed. The tests carried out with the use of a CO as a reducer, at a temperature of 1000 °C, allowed to obtain high levels of metallization of the samples for scale 91.6%, dust 66.9%, and sludge 97.3%. These results indicate that in the case of sludge and scale, the degree of metallization meets the requirements for charge materials used in both blast furnace (BF) and electric arc furnace (EAF) steelmaking processes, while in the case of reduced dust, this material can be used as enriched charge in the blast furnace process. Reduction studies were also carried out using a gas mixture of CO and H2 (50 vol.% CO + 50 vol.% H2). The introduction of hydrogen as a reducing agent in reduction processes meets the urgent need of reducing CO2 emissions. The obtained results confirm the great importance and influence of the selection of the right amount of reducer on the achievement of a high degree of metallization and that these materials can be a valuable source of metallic charge for blast furnace and steelmaking processes. At an earlier stage of the established research program, experiments of the iron oxides reduction from iron-bearing waste materials in a stationary layer in a Tammann furnace were also conducted.
High-Yield Production of Nano-Lateral Size Graphene Oxide by High-Power Ultrasonication
Authors: Timochenco Licínia , Costa-Almeida Raquel , Bogas Diana , Silva Filipa A. L. S. , Silva Joana , Pereira André , Magalhães Fernão D. , Pinto Artur M.
Published: April 2021

Nanographene oxide (GOn) constitutes a nanomaterial of high value in the biomedical field. However, large scale production of highly stable aqueous dispersions of GOn is yet to be achieved. In this work, we explored high-power ultrasonication as a method to reduce particle size of GO and characterized the impact of the process on the physicochemical properties of the material. GOn was obtained with lateral dimensions of 99 ± 43 nm and surface charge of −39.9 ± 2.2 mV. High-power ultrasonication enabled an improvement of stability features, particularly by resulting in a decrease of the average particle size, as well as zeta potential, in comparison to GO obtained by low-power exfoliation and centrifugation (287 ± 139 nm; −29.7 ± 1.2 mV). Remarkably, GOn aqueous dispersions were stable for up to 6 months of shelf-time, with a global process yield of 74%. This novel method enabled the production of large volumes of highly concentrated (7.5 mg mL−1) GOn aqueous dispersions. Chemical characterization of GOn allowed the identification of characteristic oxygen functional groups, supporting high-power ultrasonication as a fast, efficient, and productive process for reducing GO lateral size, while maintaining the material’s chemical features.
A New Type of Hierarchical Honeycomb in-Plane Impact Study
Authors: Song Hang , Zhang Chenyang , Wang Pengyu , Meng Lingzhi , Wang Zhenqing
Published: April 2021

Honeycomb materials have low density, high specific strength and stiffness, impact resistance, and good sound insulation effect, and therefore are widely used in aerospace, automobile, and ship field applications. In this paper, we study the in-plane impact response of a second-order hierarchical honeycomb (SHH) material. Its main structure is a hexagonal honeycomb, and the substructure is composed of an augmented double arrow honeycomb (ADAH) negative Poisson’s ratio unit. Through a finite element simulation, the failure stress of an hierarchical honeycomb in two directions of quasi-static crushing and dynamic crushing was analyzed; the failure stress of the hierarchical honeycomb under different densities, different speeds, and different substructures was discussed; and the theoretical failure stress was verified. The numerical analysis results show that a second-order hierarchical honeycomb (SHH) has better collapse stress than a first-order regular hexagonal honeycomb (FHH) and an augmented double arrow honeycomb (ADAH).
Synergistic Enhancement of Thermoelectric Performances by Cl-Doping and Pb-Excess in (Pb,Sn)Se Topological Crystal Insulator
Authors: Kim Jin Hee , Kim Gareoung , Byeon Seokyeong , Jin Hyungyu , Rhyee Jong-Soo
Published: April 2021

We investigated the thermoelectric properties of the Pb0.75Sn0.25Se and Pb0.79Sn0.25Se1−xClx (x = 0.0, 0.2, 0.3, 0.5, 1.0, 2.0 mol.%) compounds, synthesized by hot-press sintering. The electrical transport properties showed that low concentration doping of Cl (below 0.3 mol.%) in the Pb-excess (Pb,Sn)Se samples increased the carrier concentration and the Hall mobility by the increase of carriers’ mean free path. The effective mass of the carrier was also enhanced from the measurements of the Seebeck coefficient. The enhanced effective masses of the carrier by the Cl-doping can be understood by the enhanced electron-phonon interaction, caused by the crystalline mirror symmetry breaking. The significantly decreased lattice thermal conductivities showed that the crystalline mirror symmetry breaking decreased the lattice thermal conductivity of the Pb-excess (Pb,Sn)Se. By the Cl-doping and the Pb-excess’s synergistic effect, which can suppress the bipolar effect, the zT values of x = 0.2 and 0.3 mol.% reached 0.8 at 773 K. Therefore, we suggest that Pb-excess and the crystalline mirror symmetry breaking by Cl-doping are effective for high thermoelectric performance in the (Pb,Sn)Se.
Mechanical Behavior of Different Restorative Materials and Onlay Preparation Designs in Endodontically Treated Molars
Authors: Gomes de Carvalho Ana Beatriz , de Andrade Guilherme Schmitt , Mendes Tribst João Paulo , Grassi Elisa Donária Aboucauch , Ausiello Pietro , Saavedra Guilherme de Siqueira Ferreira Anzaloni , Bressane Adriano , Marques de Melo Renata , Borges Alexandre Luiz Souto
Published: April 2021

This study evaluated the effect of the combination of three different onlay preparation designs and two restorative materials on the stress distribution, using 3D-finite element analysis. Six models of first lower molars were created according to three preparation designs: non-retentive (nRET), traditional with occlusal isthmus reduction (IST), and traditional without occlusal isthmus reduction (wIST); and according to two restorative materials: lithium-disilicate (LD) and nanoceramic resin (NR). A 600 N axial load was applied at the central fossa. All solids were considered isotropic, homogeneous, and linearly elastic. A static linear analysis was performed, and the Maximum Principal Stress (MPS) criteria were used to evaluate the results and compare the stress in MPa on the restoration, cement layer, and tooth structure (enamel and dentin). A novel statistical approach was used for quantitative analysis of the finite element analysis results. On restoration and cement layer, nRET showed a more homogeneous stress distribution, while the highest stress peaks were calculated for LD onlays (restoration: 69–110; cement layer: 10.2–13.3). On the tooth structure, the material had more influence, with better results for LD (27–38). It can be concluded that nRET design showed the best mechanical behavior compared to IST and wIST, with LD being more advantageous for tooth structure and NR for the restoration and cement layer.
Comparison of VOC Emissions Produced by Different Types of Adhesives Based on Test Chambers
Authors: Kozicki Mateusz , Guzik Katarzyna
Published: April 2021

Volatile organic compounds (VOCs) emitted from building materials into the indoor air may cause discomfort associated with a perceptible chemical odour and may irritate the upper respiratory tract. Hence, it is vital to control indoor air pollution sources, such as interior finishing materials, including adhesives. The study involved carrying out a series of experimental tests of VOC emissions of 25 adhesives based on the ISO 16000 series standards. The research concerns three groups of construction adhesives with indoor applications, i.e., flooring (10), finishing walls and ceilings (6), and for other applications such as edge-gluing or gluing tiles or mirrors (9) differing in chemical composition. A series of temperature tests were carried out for a representative floor adhesive at selected temperatures: 25 °C, 35 °C and 45 °C. The theoretical correlation approach was adopted to characterise the relationship between the emission rate and temperature of selected chemical compounds.
Positive Influence of Liquid Sodium Silicate on the Setting Time, Polymerization, and Strength Development Mechanism of MSWI Bottom Ash Alkali-Activated Mortars
Authors: Jin Lei , Huang Guodong , Li Yongyu , Zhang Xingyu , Ji Yongsheng , Xu Zhishan
Published: April 2021

Setting time and mechanical properties are key metrics needed to assess the properties of municipal solid waste incineration (MSWI) bottom ash alkali-activated samples. This study investigated the solidification law, polymerization, and strength development mechanism in response to NaOH and liquid sodium silicate addition. Scanning electron microscopy and X-ray diffraction were used to identify the formation rules of polymerization products and the mechanism of the underlying polymerization reaction under different excitation conditions. The results identify a strongly alkaline environment as the key factor for the dissolution of active substances as well as for the formation of polymerization products. The self-condensation reaction of liquid sodium silicate in the supersaturated state (caused by the loss of free water) is the major reason for the rapid coagulation of alkali-activated samples. The combination of both NaOH and liquid sodium silicate achieves the optimal effect, because they play a compatible coupling role.
Strength Characteristics and Microstructure of Cement Stabilized Soft Soil Admixed with Silica Fume
Authors: Jiang Nan , Wang Changming , Wang Zeping , Li Bailong , Liu Yi-ao
Published: April 2021

Soft soil improvement is an important subject in civil engineering, and searching for an effective admixture is an important research. Silica fume (SF) is a kind of recycled material, it can be used in engineering as a pozzolanic material. The main objective of this study is to assess the effectiveness of industrial waste silica fume (SF) as an admixture to improve the cement stabilized soft soil. The unconfined compressive test (UCT) and scanning electron microscopy (SEM) test of cement stabilized soil with different SF contents and different curing times have been carried out. UCT after 28 days revealed that the addition of SF can effectively increase the strength of cement stabilized soil and reduce the amount of cement, and 1.5% SF content is considered optimum, excessive SF will not further increase the strength. SF helped to accelerate the cement hydration reaction and significantly improve the early-age strength of stabilized soil even at 3 days, which can improve construction efficiency in actual projects. SEM analyses shows that the proper SF content could make the hydration product calcium silicate hydrate gel (CSH) fill the pores and increase the strength of the material, but excessive SF will increase the large pores content of the material and reduce the strength. This provided a basis for application of SF in improving soft soil.
Boundary Stabilization of Heat Equation with Multi-Point Heat Source
Authors: Hu Qing-Qing , Jin Feng-Fei , Yan Bao-Qiang
Published: April 2021

In this paper, we consider boundary stabilization problem of heat equation with multi-point heat source. Firstly, a state feedback controller is designed mainly by backstepping approach. Under the designed state controller, the exponential stability of closed-loop system is guaranteed. Then, an observer-based output feedback controller is proposed. We prove the exponential stability of resulting closed-loop system using operator semigroup theory. Finally, the designed state and output feedback controllers are effective via some numerical simulations.
A New Compromise Design Plan for Accelerated Failure Time Models with Temperature as an Acceleration Factor
Authors: Mariñas-Collado Irene , Rivas-López M. Jesús , Rodríguez-Díaz Juan M. , Santos-Martín M. Teresa
Published: April 2021

An accelerated life test of a product or material consists of the observation of its failure time when it is subjected to conditions that stress the usual ones. The purpose is to obtain the parameters of the distribution of the time-to-failure for usual conditions through the observed failure times. A widely used method to provoke an early failure in a mechanism is to modify the temperature at which it is used. In this paper, the statistically optimal plan for Accelerated Failure Time (AFT) models, when the accelerated failure process is described making use of Arrhenius or Eyring equations, was calculated. The result was a design that had only two stress levels, as is common in other AFT models and that is not always practical. A new compromise plan was presented as an alternative to the widely used “4:2:1 plan”. The three-point mixture design proposed specified a support point in the interval that was optimal for the estimation of the parameters in AFT models, rather than simply the middle point. It was studied in comparison to different commonly used designs, and it proved to have a higher D-efficiency than the others.
Integrated Omics Strategy Reveals Cyclic Lipopeptides Empedopeptins from Massilia sp. YMA4 and Their Biosynthetic Pathway
Authors: Ho Shang-Tse , Ho Ying-Ning , Lin Chih , Hsu Wei-Chen , Lee Han-Jung , Peng Chia-Chi , Cheng Han-Tan , Yang Yu-Liang
Published: April 2021

Empedopeptins—eight amino acid cyclic lipopeptides—are calcium-dependent antibiotics that act against Gram-positive bacteria such as Staphylococcus aureus by inhibiting cell wall biosynthesis. However, to date, the biosynthetic mechanism of the empedopeptins has not been well identified. Through comparative genomics and metabolomics analysis, we identified empedopeptin and its new analogs from a marine bacterium, Massilia sp. YMA4. We then unveiled the empedopeptin biosynthetic gene cluster. The core nonribosomal peptide gene null-mutant strains (ΔempC, ΔempD, and ΔempE) could not produce empedopeptin, while dioxygenase gene null-mutant strains (ΔempA and ΔempB) produced several unique empedopeptin analogs. However, the antibiotic activity of ΔempA and ΔempB was significantly reduced compared with the wild-type, demonstrating that the hydroxylated amino acid residues of empedopeptin and its analogs are important to their antibiotic activity. Furthermore, we found seven bacterial strains that could produce empedopeptin-like cyclic lipopeptides using a genome mining approach. In summary, this study demonstrated that an integrated omics strategy can facilitate the discovery of potential bioactive metabolites from microbial sources without further isolation and purification.
Effect of Oversulfation on the Composition, Structure, and In Vitro Anti-Lung Cancer Activity of Fucoidans Extracted from Sargassum aquifolium
Authors: Hsiao Hui-Hua , Wu Tien-Chiu , Tsai Yung-Hsiang , Kuo Chia-Hung , Huang Ren-Han , Hong Yong-Han , Huang Chun-Yung
Published: April 2021

Intensive efforts have been undertaken in the fields of prevention, diagnosis, and therapy of lung cancer. Fucoidans exhibit a wide range of biological activities, which are dependent on the degree of sulfation, sulfation pattern, glycosidic branches, and molecular weight of fucoidan. The determination of oversulfation of fucoidan and its effect on anti-lung cancer activity and related signaling cascades is challenging. In this investigation, we used a previously developed fucoidan (SCA), which served as a native fucoidan, to generate two oversulfated fucoidan derivatives (SCA-S1 and SCA-S2). SCA, SCA-S1, and SCA-S2 showed differences in compositions and had the characteristic structural features of fucoidan by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analyses. The anticancer properties of SCA, SCA-S1, and SCA-S2 against human lung carcinoma A-549 cells were analyzed in terms of cytotoxicity, cell cycle, Bcl-2 expression, mitochondrial membrane potential (MMP), expression of caspase-3, cytochrome c release, Annexin V/propidium iodide (PI) staining, DNA fragmentation, and the underlying signaling cascades. Our findings indicate that the oversulfation of fucoidan promotes apoptosis of lung cancer cells and the mechanism may involve the Akt/mTOR/S6 pathway. Further in vivo research is needed to establish the precise mechanism whereby oversulfated fucoidan mitigates the progression of lung cancer.
Skeletal Muscle Damage in COVID-19: A Call for Action
Authors: Ali Amira Mohammed , Kunugi Hiroshi
Published: April 2021

Both laboratory investigations and body composition quantification measures (e.g., computed tomography, CT) portray muscle loss in symptomatic Coronavirus disease 2019 (COVID-19) patients. Muscle loss is associated with a poor prognosis of the disease. The exact mechanism of muscle damage in COVID-19 patients, as well as the long-term consequences of muscle injury in disease survivors, are unclear. The current review briefly summarizes the literature for mechanisms, assessment measures, and interventions relevant to skeletal muscle insult in COVID-19 patients. Muscle injury is likely to be attributed to the cytokine storm, disease severity, malnutrition, prolonged physical inactivity during intensive care unit (ICU) stays, mechanical ventilation, and myotoxic drugs (e.g., dexamethasone). It has been assessed by imaging and non-imaging techniques (e.g., CT and electromyography), physical performance tests (e.g., six-minute walk test), anthropometric measures (e.g., calf circumference), and biomarkers of muscle dystrophy (e.g., creatine kinase). Interventions directed toward minimizing muscle loss among COVID-19 patients are lacking. However, limited evidence shows that respiratory rehabilitation improves respiratory function, muscle strength, quality of life, and anxiety symptoms in recovering older COVID-19 patients. Neuromuscular electrical stimulation may restore muscle condition in ICU-admitted patients, albeit empirical evidence is needed. Given the contribution of malnutrition to disease severity and muscle damage, providing proper nutritional management for emaciated patients may be one of the key issues to achieve a better prognosis and prevent the after-effects of the disease. Considerable attention to longer-term consequences of muscle injury in recovering COVID-19 patients is necessary.
Concentration of Municipal MBBR Effluent by FO for Resource Recovery: Batch Experiments in Side-Stream Configuration
Authors: Thelin Willy Røstum , Sivertsen Edvard , Raspati Gema , Azrague Kamal , Helness Herman
Published: April 2021

A novel approach for resource recovery includes forward osmosis (FO) as a concentration step in municipal wastewater treatment. The current study investigates different pre-treatment strategies including biological treatment with a moving-bed bioreactor (MBBR) at different loading rates and particle removal by filtration and sedimentation. Membrane performance and recovery potential for energy and nutrients were investigated in laboratory-scale FO experiments in batch mode using pre-treated municipal wastewater as feed and 35 g/L NaCl as a draw solution. Initial water fluxes were in the range of 6.3 to 8.0 L/(m2·h). The baseline fluxes were modelled to account for flux decline due to concentration effects and to enable the prediction of flux decline due to membrane fouling. Fouling-related flux decline varied from 0 to 31%. Both organic fouling and precipitation of CaCO3 and CaHPO4 were identified by using SEM–EDS. High-rate flushing resulted in complete flux recovery under most conditions. Scaling could be avoided by lowering the pH. Two operation strategies were tested to achieve this: (1) applying a bioreactor with a low organic loading rate to achieve high nitrification, and (2) adding a strong acid. A low organic loading rate and the use of additional particle removal were efficient measures that reduced organic/particulate fouling. The recovery potentials for COD and phosphorous in FO concentrate were close to 100%.
Trends in Plasticity of Metals and Alloys
Authors: Lebyodkin Mikhaïl A. , Taupin Vincent
Published: April 2021

Having been at the center of technological progress for thousands of years, metals continue to be a primary material in our lives today [...]
Analysis of As-Built Microstructures and Recrystallization Phenomena on Inconel 625 Alloy Obtained via Laser Powder Bed Fusion (L-PBF)
Authors: De Terris Thibaut , Castelnau Olivier , Hadjem-Hamouche Zehoua , Haddadi Halim , Michel Vincent , Peyre Patrice
Published: April 2021

The microstructures induced by the laser-powder bed fusion (L-PBF) process have been widely investigated over the last decade, especially on austenitic stainless steels (AISI 316L) and nickel-based superalloys (Inconel 718, Inconel 625). However, the conditions required to initiate recrystallization of L-PBF samples at high temperatures require further investigation, especially regarding the physical origins of substructures (dislocation densities) induced by the L-PBF process. Indeed, the recrystallization widely depends on the specimen substructure, and in the case of the L-PBF process, the substructure is obtained during rapid solidification. In this paper, a comparison is presented between Inconel 625 specimens obtained with different laser-powder bed fusion (L-PBF) conditions. The effects of the energy density (VED) values on as-built and heat-under microstructures are also investigated. It is first shown that L-PBF specimens created with high-energy conditions recrystallize earlier due to a larger density of geometrically necessary dislocations. Moreover, it is shown that lower energy densities offers better tensile properties for as-built specimens. However, an appropriate heat treatment makes it possible to homogenize the tensile properties.
Electroosmotic Flow of Viscoelastic Fluid through a Constriction Microchannel
Authors: Ji Jianyu , Qian Shizhi , Liu Zhaohui
Published: April 2021

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which use viscoelastic non-Newtonian fluid. This study numerically investigates the EOF of viscoelastic fluid through a 10:1 constriction microfluidic channel connecting two reservoirs on either side. The flow is modelled by the Oldroyd-B (OB) model coupled with the Poisson–Boltzmann model. EOF of polyacrylamide (PAA) solution is studied as a function of the PAA concentration and the applied electric field. In contrast to steady EOF of Newtonian fluid, the EOF of PAA solution becomes unstable when the applied electric field (PAA concentration) exceeds a critical value for a fixed PAA concentration (electric field), and vortices form at the upstream of the constriction. EOF velocity of viscoelastic fluid becomes spatially and temporally dependent, and the velocity at the exit of the constriction microchannel is much higher than that at its entrance, which is in qualitative agreement with experimental observation from the literature. Under the same apparent viscosity, the time-averaged velocity of the viscoelastic fluid is lower than that of the Newtonian fluid.
An Accurate Model to Calculate CO2 Solubility in Pure Water and in Seawater at Hydrate–Liquid Water Two-Phase Equilibrium
Authors: Di Mengyao , Sun Rui , Geng Lantao , Lu Wanjun
Published: April 2021

Understanding of CO2 hydrate–liquid water two-phase equilibrium is very important for CO2 storage in deep sea and in submarine sediments. This study proposed an accurate thermodynamic model to calculate CO2 solubility in pure water and in seawater at hydrate–liquid water equilibrium (HLWE). The van der Waals–Platteeuw model coupling with angle-dependent ab initio intermolecular potentials was used to calculate the chemical potential of hydrate phase. Two methods were used to describe the aqueous phase. One is using the Pitzer model to calculate the activity of water and using the Poynting correction to calculate the fugacity of CO2 dissolved in water. Another is using the Lennard–Jones-referenced Statistical Associating Fluid Theory (SAFT-LJ) equation of state (EOS) to calculate the activity of water and the fugacity of dissolved CO2. There are no parameters evaluated from experimental data of HLWE in this model. Comparison with experimental data indicates that this model can calculate CO2 solubility in pure water and in seawater at HLWE with high accuracy. This model predicts that CO2 solubility at HLWE increases with the increasing temperature, which agrees well with available experimental data. In regards to the pressure and salinity dependences of CO2 solubility at HLWE, there are some discrepancies among experimental data. This model predicts that CO2 solubility at HLWE decreases with the increasing pressure and salinity, which is consistent with most of experimental data sets. Compared to previous models, this model covers a wider range of pressure (up to 1000 bar) and is generally more accurate in CO2 solubility in aqueous solutions and in composition of hydrate phase. A computer program for the calculation of CO2 solubility in pure water and in seawater at hydrate–liquid water equilibrium can be obtained from the corresponding author via email.
Molecular Dynamics Study of Structural Properties of Refining Slag with Various CaO/Al2O3 Ratios
Authors: Zhao Hongxuan , Li Jingshe , Yang Shufeng , Liu Jie , Liu Wei
Published: April 2021

SiO2-Al2O3-CaO-MgO is the main type of refining slag in a ladle furnace. Here the effects of the CaO/Al2O3 mass ratio on the structural properties of the refining slag system are studied by molecular dynamics simulations. The pair distribution function, coordination number, micro-structure unit and diffusion capacity were analyzed. An increase in the CaO/Al2O3 ratio did not change the bond lengths of these units. However, an increase of the CaO/Al2O3 ratio caused more charge compensators to be introduced into the refining slag system, which led to conversion of free oxygen and non-bridging oxygen to tricluster oxygen and bridging oxygen in the system. Moreover, this augmented the content of relatively stable 4- and 5-coordinate Al. As the micro-structure of the system became more complex, the overall diffusion capacity of the refining slag became poorer. In the micro-structure, the diffusion capabilities of different atoms decreased in the following order: Mg > Ca > O > Al > Si.
Twin Induced Reduction of Seismic Anisotropy in Lawsonite Blueschist
Authors: Choi Seungsoon , Fabbri Olivier , Topuz Gültekin , Okay Aral I. , Jung Haemyeong
Published: April 2021

Lawsonite is an important mineral for understanding seismic anisotropy in subducting oceanic crust due to its large elastic anisotropy and prevalence in cold subduction zones. However, there is insufficient knowledge of how lawsonite twinning affects seismic anisotropy, despite previous studies demonstrating the presence of twins in lawsonite. This study investigated the effect of lawsonite twinning on the crystal preferred orientation (CPO), CPO strength, and seismic anisotropy using lawsonite blueschists from Alpine Corsica (France) and the Sivrihisar Massif (Turkey). The CPOs of the minerals are measured with an electron backscatter diffraction instrument attached to a scanning electron microscope. The electron backscatter diffraction analyses of lawsonite reveal that the {110} twin in lawsonite is developed, the [001] axes are strongly aligned subnormal to the foliation, and both the [100] and [010] axes are aligned subparallel to the foliation. It is concluded that the existence of twins in lawsonite could induce substantial seismic anisotropy reduction, particularly for the maximum S-wave anisotropy in lawsonite and whole rocks by up to 3.67% and 1.46%, respectively. Lawsonite twinning needs to be considered when determining seismic anisotropy in the subducting oceanic crust in cold subduction zones.
SIMS U-Pb Dating of Uraninite from the Guangshigou Uranium Deposit: Constraints on the Paleozoic Pegmatite-Type Uranium Mineralization in North Qinling Orogen, China
Authors: Guo Guolin , Bonnetti Christophe , Zhang Zhanshi , Li Guanglai , Yan Zhaobin , Wu Jianhua , Wu Yong , Liu Xiaodong , Wu Bin
Published: April 2021

Pegmatite-type uranium mineralization occurs in the Shangdan domain of the North Qinling Orogenic Belt, representing a significant uraniferous province. The Guangshigou deposit is the largest U deposit of the district. Within the North Qinling area, a series of Caledonian granitic igneous rocks intruded the Proterozoic metamorphic rocks of the Qinling Group in two magmatic stages: (i) the Early Silurian Huichizi granite that was derived from a low degree of partial melting of thickened lower basaltic crust combined with mantle-derived materials following the subduction of the Shangdan Ocean; and (ii) the Late Silurian–Early Devonian Damaogou granite and associated pegmatites derived from the same source but emplaced in a late tectonic post-collisional extension environment. In the Guangshigou deposit, the U mineralization mainly occurs as uraninite disseminated in U-rich granitic biotite pegmatites, which formed by assimilation-fractional crystallization magmatic processes. Petrographic observations showed evidence for coeval crystallization of uraninite and other rock-forming minerals of the host pegmatite including quartz, feldspar, biotite, zircon, monazite, apatite, and xenotime. In addition, the low U/Th ratios (~19) and Th, REE, and Y enrichments characterized a magmatic origin for uraninite, which was likely derived from fractionated high-K calc-alkaline pegmatitic magma that experienced various degrees of crustal material contamination. In situ U-Pb isotopic dating performed by Secondary-Ion Mass Spectrometry (SIMS) on uraninite from the Guangshigou deposit yielded a crystallization age of 412 ± 3 Ma, which is concomitant (within errors) with the emplacement age of the host pegmatite (415 ± 2 Ma) and constrained the U ore genesis to the Early Devonian, which corresponds to the late Caledonian post-collisional extension in the North Qinling area. Uraninite then experienced various degrees of metamictization and/or post-Caledonian hydrothermal alteration characterized by an alteration rim associated with coffinite, chlorite and limonite. Finally, the characteristics of the pegmatite-related Guangshigou deposit exhibiting Th-rich uraninite which was the product of assimilation-fractional crystallization of pegmatitic magma defined a model significantly different than the one established for the world-class Rössing deposit characterized by Th-poor uraninite hosted in alaskite dykes formed by low degree of partial melting of U-rich metasediments.
Phytochemical Differentiation of Saffron (Crocus sativus L.) by High Resolution Mass Spectrometry Metabolomic Studies
Authors: Gikas Evangelos , Koulakiotis Nikolaos Stavros , Tsarbopoulos Anthony
Published: April 2021

The metabolite profiling of saffron (Crocus sativus L.) from several countries was measured by using ultra-performance liquid chromatography combined with high resolution mass spectrometry (UPLC-HR MS). Multivariate statistical analysis was employed to distinguish among the several samples of C. sativus L. from Greece, Italy, Morocco, Iran, India, Afghanistan and Kashmir. The results of this study showed that the phytochemical content in the samples of C. sativus L. were obviously diverse in the different countries of origin. The metabolomics approach was deemed to be the most suitable in order to evaluate the enormous array of putative metabolites among the saffron samples studied, and was able to provide a comparative phytochemical screening of these samples. Several markers have been identified that aided the differentiation of a group from its counterparts. This can be important for the selection of the appropriate saffron sample, in view of its health-promoting effect which occurs through the modulation of various biological and physiological processes.
Synthesis, Spectroscopic Properties and Redox Behavior Kinetics of Rare-Earth Bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato Metal Complexes with Er, Lu and Yb
Authors: Erzunov Dmitry A. , Botnar Anna A. , Domareva Natalia P. , Tikhomirova Tatiana V. , Vashurin Arthur S.
Published: April 2021

Novel bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato of complexes erbium, lutetium and ytterbium were synthesized using a template fusion method to prevent any polymerization process. The complexes were separated from the reaction mixtures and characterized by NMR, IR and electron absorption spectroscopy. The spectroscopic properties of the metal phthalocyaninates in chloroform, acetone and tetrahydrofuran were studied. The regular bathochromic shift in the Er–Yb–Lu series was determined. In acetone medium all the complexes obtained were found to exist in an equilibrium state between neutral and reduced forms. The linearity of Lambert-Bouger-Beer curves makes it possible to study the kinetics of redox processes in the presence of phenylhydrazine and bromine. The lutetium complex showed better reducing properties and turned fully into the reduced form, while the erbium and ytterbium ones changed only partially. Upon oxidizing all the phthalocyaninates transformed into a mixture of oxidized and neutral-radical forms. The extinction coefficients and effective redox constants were calculated.
Elemental Characterization of Ciders and Other Low-Percentage Alcoholic Beverages Available on the Polish Market
Authors: Gajek Magdalena , Pawlaczyk Aleksandra , Wysocki Piotr , Szynkowska-Jozwik Malgorzata I.
Published: April 2021

Seventy-three samples of alcoholic beverages and juices that were purchased on the Polish market and home-made were analyzed for their elemental profiles. The levels of 23 metals were determined by ICP-MS (Ag, Ba, Bi, Cd, Co, Cr, Li, Mn, Ni, Pb, Sr and Tl), ICP-OES (Al, B, Ca, Cu, Fe, K, Mg, Na, Ti and Zn) and CVAAS (Hg) techniques in twenty-five samples of ciders widely available on the Polish market; six samples of home-made ciders; two samples of juices used in the production of these ciders; and forty samples of low-percentage, flavored alcoholic beverages based on beer. The gathered analytical data confirmed that the final elemental fingerprint of a product is affected by the elemental fingerprint of the ingredients used (apple variety) as well as the technology and equipment used by the producer, and in the case of commercial ciders, also the impact of type of the packaging used was proven. These factors are specific to each producer and the influence of the mentioned above parameters was revealed as a result of the performed analysis. Additionally, the inclusion of the home-made ciders in the data set helped us to understand the potential origin of some elements, from the raw materials to the final products. The applied statistical tests revealed (Kruskal–Wallis and ANOVA) the existence of statistically significant differences in the concentration of the following metals: Ag, Al, B, Bi, Co, Cr, Cu, Fe, K, Li, Mg, Na, Ni, Ti and Zn in terms of the type of cider origin (commercial and home-made). In turn, for different packaging (can or bottle) within one brand of commercial cider, the existence of statistically significant differences for Cu, Mn and Na was proved. The concentrations of all determined elements in the commercial cider from the Polish market and home-made cider samples can be considered as nontoxic, because the measured levels of elements indicated in the regulations were lower than the allowable limits. Moreover, the obtained results can be treated as preliminary for the potential authentication of products in order to distinguish the home-made (fake) from the authentic products, especially for premium-class alcoholic beverages.
A Stretchable Pillararene-Containing Supramolecular Polymeric Material with Self-Healing Property
Authors: Zhao Meng , Li Changjun , Shan Xiaotao , Han Huijing , Zhao Qiuhua , Xie Meiran , Chen Jianzhuang , Liao Xiaojuan
Published: April 2021

Constructing polymeric materials with stretchable and self-healing properties arise increasing interest in the field of tissue engineering, wearable electronics and soft actuators. Herein, a new type of supramolecular cross-linker was constructed through host-guest interaction between pillar[5]arene functionalized acrylate and pyridinium functionalized acrylate, which could form supramolecular polymeric material via photo-polymerization of n-butyl acrylate (BA). Such material exhibited excellent tensile properties, with maximum tensile strength of 3.4 MPa and strain of 3000%, respectively. Moreover, this material can effectively dissipate energy with the energy absorption efficiency of 93%, which could be applied in the field of energy absorbing materials. In addition, the material showed self-healing property after cut and responded to competitive guest.
Polyphenolic Compounds Extracted and Purified from Buddleja Globosa Hope (Buddlejaceae) Leaves Using Natural Deep Eutectic Solvents and Centrifugal Partition Chromatography
Authors: Torres-Vega Jeniffer , Gómez-Alonso Sergio , Pérez-Navarro José , Alarcón-Enos Julio , Pastene-Navarrete Edgar
Published: April 2021

Chemical profiling of Buddleja globosa was performed by high-performance liquid chromatography coupled to electrospray ionization (HPLC-DAD-ESI-IT/MS) and quadrupole time-of-flight high-resolution mass spectrometry (HPLC-ESI-QTOF/MS). The identification of 17 main phenolic compounds in B. globosa leaf extracts was achieved. Along with caffeoyl glucoside isomers, caffeoylshikimic acid and several verbascoside derivatives (β-hydroxyverbascoside and β-hydroxyisoverbascoside) were identified. Among flavonoid compounds, the presence of 6-hydroxyluteolin-7-O-glucoside, quercetin-3-O-glucoside, luteolin 7-O-glucoside, apigenin 7-O-glucoside was confirmed. Campneoside I, forsythoside B, lipedoside A and forsythoside A were identified along with verbascoside, isoverbascoside, eukovoside and martynoside. The isolation of two bioactive phenolic compounds verbascoside and forsythoside B from Buddleja globosa (Buddlejaceae) was successfully achieved by centrifugal partition chromatography (CPC). Both compounds were obtained in one-step using optimized CPC methodology with the two-phase solvent system comprising ethyl acetate-n-butanol-ethanol-water (0.25:0.75:0.1:1, v/v). Additionally, eight Natural Deep Eutectic Solvents (NADESs) were tested for the extraction of polyphenols and compared with 80% methanol. The contents of verbascoside and luteolin 7-O-glucoside after extraction with 80% methanol were 26.165 and 3.206 mg/g, respectively. Among the NADESs tested in this study, proline- citric acid (1:1) and choline chloride-1, 2- propanediol (1:2) were the most promising solvents. With these NADES, extraction yields for verbascoside and luteolin 7-O-glucoside were 51.045 and 4.387 mg/g, respectively. Taken together, the results of this study confirm that CPC enabled the fast isolation of bioactive polyphenols from B. globosa. NADESs displayed higher extraction efficiency of phenolic and therefore could be used as an ecofriendly alternative to classic organic solvents.
Metabolic Evaluation of Urine from Patients Diagnosed with High Grade (HG) Bladder Cancer by SPME-LC-MS Method
Authors: Łuczykowski Kamil , Warmuzińska Natalia , Operacz Sylwia , Stryjak Iga , Bogusiewicz Joanna , Jacyna Julia , Wawrzyniak Renata , Struck-Lewicka Wiktoria , Markuszewski Michał J. , Bojko Barbara
Published: April 2021

Bladder cancer (BC) is a common malignancy of the urinary system and a leading cause of death worldwide. In this work, untargeted metabolomic profiling of biological fluids is presented as a non-invasive tool for bladder cancer biomarker discovery as a first step towards developing superior methods for detection, treatment, and prevention well as to further our current understanding of this disease. In this study, urine samples from 24 healthy volunteers and 24 BC patients were subjected to metabolomic profiling using high throughput solid-phase microextraction (SPME) in thin-film format and reversed-phase high-performance liquid chromatography coupled with a Q Exactive Focus Orbitrap mass spectrometer. The chemometric analysis enabled the selection of metabolites contributing to the observed separation of BC patients from the control group. Relevant differences were demonstrated for phenylalanine metabolism compounds, i.e., benzoic acid, hippuric acid, and 4-hydroxycinnamic acid. Furthermore, compounds involved in the metabolism of histidine, beta-alanine, and glycerophospholipids were also identified. Thin-film SPME can be efficiently used as an alternative approach to other traditional urine sample preparation methods, demonstrating the SPME technique as a simple and efficient tool for urinary metabolomics research. Moreover, this study’s results may support a better understanding of bladder cancer development and progression mechanisms.