bluuebunny/crossref_metadata_2025 huggingface dataset:
The Anisotropic Electrochemical Machinability of Laser Cladding Deposited Ti6Al4V Alloy in NaCl Solution
Authors: Li Jiaqiang , Yang Yuan , Zhu Gangxian , Sun Chengfeng , Chen Yiyang , Wang Kejun , Shi Shihong
Published: May 2022

The hybrid manufacturing method of laser cladding deposition (LCD) additive manufacturing and electrochemical machining (ECM) is a promising approach to advanced manufacturing technology for difficult machined materials. The anisotropic electrochemical performance of LCD-produced Ti6Al4V alloy was studied in 15 wt.% NaCl solution by polarization curve measurements and ECM tests. The horizontal-plane (X0Y plane) exhibits a more stable passive film in both static electrolyte and low current density ECM processes than the vertical-plane (X0Z plane). Additionally, the horizontal-plane exhibits a higher material removal rate and more consistent dissolved surface roughness in comparison with the vertical-plane during the high current density ECM process. The microstructure of the LCD-produced Ti6Al4V alloy on the horizontal-plane consisted of equiaxed-like prior-β grains and slightly finer α-laths but was composed by columnar prior-β grains and coarser α-laths on the vertical-plane. These differences in the microstructural characteristics produce the distinctions observed in the electrochemical dissolution behavior and electrochemical machinability on the horizontal- and vertical-planes.
Real-Time Observation of Magnetic Domain Structure Changes with Increasing Temperature for Z-Type Hexagonal Ferrite
Authors: Kim Sung-Dae , Park Ihho
Published: May 2022

Z-type hexagonal ferrites have recently received attention for their room-temperature magnetoelectric (ME), which is activated when the temperature at which the transverse-conical spin-state transitions to a ferrimagnetic state is increased. The changes in the magnetic domain structure at the transition have been well-documented; however, they are still not understood in detail. In the present study, Lorentz transmission electron microscopy (TEM) analysis combined with an in situ heating experiment was conducted to demonstrate the shift in magnetic domain structure during the transition from the transverse-conical spin arrangement to a ferrimagnetic spin order. The dynamics of the magnetic domain structure changes with the increasing temperature were acquired in real-time. At 490 K, the magnetization transition from the transverse-conical spin state to the ferromagnetic state was demonstrated. Cross-tie domain walls formed during the magnetic transition process. The increased effect of the demagnetizing field applied to the 180° magnetic domains was caused by a lower magnetocrystalline anisotropy (MCA) at the easy axis of magnetization.
Liquation Cracking Susceptibility and Mechanical Properties of 7075 Aluminum Alloy GTAW Joints
Authors: Li Zhuoxin , Zhang Yulin , Li Hong , Wang Yipeng , Wang Lijuan , Zhang Yu
Published: May 2022

In this work, aluminum alloy 7075-T651 was welded by using customized Al-Cu-Si and Al-Cu-Mg-Zn filler wire during gas tungsten arc welding. The liquation cracking susceptibility of the joints was tested under a circular-patch welding experiment. Besides, the temperature vs. solid fraction curves (T-fS) was calculated for different samples to reveal the formation mechanism of liquation cracking. The joint was susceptible to liquation cracking if (fS)weld > (fS)workpiece during the cooling stage. The results of the circular-patch welding experiment show that the liquation cracking susceptibility of the joint by using ER5356, Al-Cu1.5-Si4.5, Al-Cu3.0-Si2.5, Al-Cu4.5-Si1.5, Al-Cu2.3-Mg2.3-Zn6.6 and Al-Cu2.2-Mg2.0-Zn7.8 filler metal is 22.8%, 8.3%, 2.8%, 2.8%, 3.3% and 1.4%, respectively. The mechanical test shows that the data dispersion of the 7075 gas tungsten arc welding joint can be decreased by eliminating the liquation crack.
Ultra-Violet Protection and Anti-Static Characteristics with Heat Release/Shielding of Al2O3/ATO/TiO2-Imbedded Multi-Functional Fabrics
Authors: Kim Hyun-Ah
Published: May 2022

This study examined the ultra-violet (UV) protection and anti-static characteristics with heat release by far-infrared (FIR) emissivity of Al2O3/Antimony Tin Oxide (ATO)/TiO2-imbedded PET fabrics according to the weight (wt.) percentage of the Al2O3/ATO particles imbedded in the yarns. The fabric with lower Al2O3/ATO wt. percentage had more effective heat release than that of the fabric with higher percentage due to the heat shielding property of the ATO particles. The fabric with lower Al2O3/ATO wt. percentage (higher TiO2) exhibited higher UV protection factor (UPF) than that of the fabric with higher percentage, which suggested that the UV protection characteristic of TiO2 particles imbedded in the yarn was superior to that of the Al2O3/ATO particles. The anti-static property of the higher wt.% of ATO-imbedded fabric was superior to that of the lower wt.% of ATO-imbedded fabric, which means that ATO inorganic particles provide superior anti-static property to the Al2O3 and TiO2 particles. On the other hand, Al2O3/ATO particles imbedded in the yarns imparted an uncomfortable tactile hand feel and wear fitness to the fabrics.
Removal of Organic Dyes from Aqueous Solutions by Activated Carbons Prepared from Residue of Supercritical Extraction of Marigold
Authors: Bazan-Wozniak Aleksandra , Wolski Robert , Paluch Dorota , Nowicki Piotr , Pietrzak Robert
Published: May 2022

In the present work, we reported on the efficiency of the removal of organic dyes by adsorption on activated carbons prepared from the residue of supercritical extraction of marigold. The performance of adsorbents prepared was tested towards methyl red, methylene blue, malachite green, and crystal violet at room temperature. The effects of carbonization (500 and 700 °C) and activation (700 and 800 °C) temperatures, textural parameters, and acid-base character of the adsorbent surface on the sorption properties of the activated carbons were established. Activated carbons are characterized by low developed specific surface area, from 2 to 206 m2/g, and have a basic character of the surface (pH of carbons water extracts ranging from 10.4 to 11.2). Equilibrium adsorption isotherms were investigated. The equilibrium data were analyzed in the Langmuir, Freundlich, and Temkin models. The adsorption capacities of activated carbons studied varied from 47.62 to 102.43 mg/g towards methyl red, 53.14 to 139.72 mg/g towards methyl red, 425.46 to 622.80 towards malachite green and 155.91 to 293.75 mg/g towards crystal violet, from their water solutions. Kinetics of the adsorption of the organic dyes studied were found to be described by the pseudo-second-order model. It was proven that through the physical activation of the residue of supercritical extraction of marigold, it is possible to obtain carbonaceous materials of very high adsorption capacity towards organic pollutants.
Graphene Oxide@Heavy Metal Ions (GO@M) Complex Simulated Waste as an Efficient Adsorbent for Removal of Cationic Methylene Blue Dye from Contaminated Water
Authors: Ding Yangfan , Chen Zhe , Wu Jinglei , Abd-Elhamid Ahmed I. , Aly Hisham F. , Nayl AbdElAziz A. , Bräse Stefan
Published: May 2022

Graphene oxide (GO) was heavily used in the adsorption process of various heavy metal ions (such as copper (Cu) and iron (Fe) ions), resulting in a huge waste quantity of graphene oxide@metal ions complex. In this research, the authors try to solve this issue. Herein, the GO surface was loaded with divalent (Cu2+) and trivalent (Fe3+) heavy metal ions as a simulated waste of the heavy metal in various removal processes to form GO@Cu and (GO@Fe) composites, respectively. After that, the previous nanocomposites were used to remove cationic methylene blue (MB) dye. The prepared composites were characterized with a scanning electron microscope (SEM), transition electron microscope (TEM), Fourier transmission infrared (FTIR), Raman, and energy-dispersive X-ray (EDS) before and after the adsorption process. Various adsorption factors of the two composites towards MB-dye were investigated. Based on the adsorption isotherm information, the adsorption process of MB-dye is highly fitted with the Langmuir model with maximum capacities (mg g−1) (384.62, GO@Cu) and (217.39, GO@Fe). According to the thermodynamic analysis, the adsorption reaction of MB-species over the GO@Cu is exothermic and, in the case of GO@Fe, is endothermic. Moreover, the two composites presented excellent selectivity of adsorption of the MB-dye from the MB/MO mixture
Near-IR Luminescence of Rare-Earth Ions (Er3+, Pr3+, Ho3+, Tm3+) in Titanate–Germanate Glasses under Excitation of Yb3+
Authors: Kowalska Karolina , Kuwik Marta , Pisarska Joanna , Pisarski Wojciech A.
Published: May 2022

Inorganic glasses co-doped with rare-earth ions have a key potential application value in the field of optical communications. In this paper, we have fabricated and then characterized multicomponent TiO2-modified germanate glasses co-doped with Yb3+/Ln3+ (Ln = Pr, Er, Tm, Ho) with excellent spectroscopic properties. Glass systems were directly excited at 980 nm (the 2F7/2 → 2F5/2 transition of Yb3+). We demonstrated that the introduction of TiO2 is a promising option to significantly enhance the main near-infrared luminescence bands located at the optical telecommunication window at 1.3 μm (Pr3+: 1G4 → 3H5), 1.5 μm (Er3+: 4I13/2 → 4I15/2), 1.8 μm (Tm3+: 3F4 → 3H6) and 2.0 μm (Ho3+: 5I7 → 7I8). Based on the lifetime values, the energy transfer efficiencies (ηET) were estimated. The values of ηET are changed from 31% for Yb3+/Ho3+ glass to nearly 53% for Yb3+/Pr3+ glass. The investigations show that obtained titanate–germanate glass is an interesting type of special glasses integrating luminescence properties and spectroscopic parameters, which may be a promising candidate for application in laser sources emitting radiation and broadband tunable amplifiers operating in the near-infrared range.
Effect of High-Voltage Additives on Formation of Solid Electrolyte Interphases in Lithium-Ion Batteries
Authors: Chen Minjing , Huang Yunbo , Shi Zhepu , Luo Hao , Liu Zhaoping , Shen Cai
Published: May 2022

Solid electrolyte interphase (SEI) formed at the interface in lithium-ion batteries plays an important role in isolating electrons and permeating ions during charging/discharging processes. Therefore, the formation of a good interface is crucial for better battery performance. In this study, additives based on adiponitrile (ADN) and trimethyl borate (TMB) were employed to broaden the electrochemical window and form a good SEI layer. Electrochemical Atomic force microscopy (EC-AFM) was used for in situ studies of film-formation mechanisms in high-voltage electrolytes on high-temperature pyrolytic graphite (HOPG), as well as Li- and Mn-rich (LMR) materials. X-ray photoelectron spectroscopy (XPS) combined with electrochemical methods revealed a synergistic reaction between the two additives to form a more stable interfacial film during charging/discharging processes to yield assembled batteries with improved cycle performance, its capacity increased from below 100 mAh/g to 200 mAh/g after 50 cycles. In sum, these findings would have great significance for the development of high voltage lithium-ion batteries with enhanced performance.
Triple Perovskite Nd1.5Ba1.5CoFeMnO9−δ-Sm0.2Ce0.8O1.9 Composite as Cathodes for the Intermediate Temperature Solid Oxide Fuel Cells
Authors: Chen Yunru , Yu Tao , Jin Jiang , Zhang Hua
Published: May 2022

Triple perovskite has been recently developed for the intermediate temperature solid oxide fuel cell (IT-SOFC). The performance of Nd1.5Ba1.5CoFeMnO9−δ (NBCFM) cathodes for IT-SOFC is investigated in this work. The interfacial polarization resistance (RP) of NBCFM is 1.1273 Ω cm2~0.1587 Ω cm2 in the range of 700–800 °C, showing good electrochemical performance. The linear thermal expansion coefficient of NBCFM is 17.40 × 10−6 K−1 at 40–800 °C, which is significantly higher than that of the electrolyte. In order to further improve the electrochemical performance and reduce the thermal expansion coefficient (TEC) of NBCFM, Ce0.8Sm0.2O2−δ (SDC) is mixed with NBCFM to prepare an NBCFM-xSDC composite cathode (x = 0, 10, 20, 30, 40 wt.%). The thermal expansion coefficient decreases monotonically from 17.40 × 10−6 K−1 to 15.25 × 10−6 K−1. The surface oxygen exchange coefficient of NBCFM-xSDC at a given temperature increases from 10−4 to 10−3 cm s−1 over the po2 range from 0.01 to 0.09 atm, exhibiting fast surface exchange kinetics. The area specific resistance (ASR) of NBCFM-30%SDC is 0.06575 Ω cm2 at 800 °C, which is only 41% of the ASR value of NBCFM (0.15872 Ω cm2). The outstanding performance indicates the feasibility of NBCFM-30% SDC as an IT-SOFC cathode material. This study provides a promising strategy for designing high-performance composite cathodes for SOFCs based on triple perovskite structures.
Surface Structure of Zirconia Implants: An Integrative Review Comparing Clinical Results with Preclinical and In Vitro Data
Authors: Rohr Nadja , Hoda Blerta , Fischer Jens
Published: May 2022

Background: The purpose of this review was to analyze and correlate the findings for zirconia implants in clinical, preclinical and in vitro cell studies in relation to surface structure. Methods: Electronic searches were conducted to identify clinical, preclinical and in vitro cell studies on zirconia implant surfaces. The primary outcomes were mean bone loss (MBL) for clinical studies, bone-to-implant contact (BIC) and removal torque (RT) for preclinical studies and cell spreading, cell proliferation and gene expression for cell studies. The secondary outcomes included comparisons of data found for those surfaces that were investigated in all three study types. Results: From 986 screened titles, 40 studies were included for data extraction. In clinical studies, only micro-structured surfaces were investigated. The lowest MBL was reported for sandblasted and subsequently etched surfaces, followed by a sinter and slurry treatment and sandblasted surfaces. For BIC, no clear preference of one surface structure was observable, while RT was slightly higher for micro-structured than smooth surfaces. All cell studies showed that cell spreading and cytoskeletal formation were enhanced on smooth compared with micro-structured surfaces. Conclusions: No correlation was observed for the effect of surface structure of zirconia implants within the results of clinical, preclinical and in vitro cell studies, underlining the need for standardized procedures for human, animal and in vitro studies.
Mechanical Properties and Microstructure of Hot-Pressed Silica Matrix Composites
Authors: Wang Weili , Chen Jianqi , Sun Xiaoning , Sun Guoxun , Liang Yanjie , Bi Jianqiang
Published: May 2022

Silica is one of the most widely used ceramics due to its excellent chemical stability and dielectric property. However, its destructive brittle nature inhabits it from wider application as a functional ceramic. An improvement in toughness is a challenging topic for silica ceramic, as well as other ceramics. In the paper, silica ceramic with different types of boron nitride powders and alumina platelets was fabricated by hot-pressing. Introduction of the additives had great influence on the composites’ mechanical properties and microstructure. The silica matrix composite containing micro-sized boron nitride powders possessed the best mechanical properties, including the bending strength (134.5 MPa) and the fracture toughness (1.85 Mpa·m1/2). Meanwhile, the introduction of alumina platelets combined with boron nitride nanosheets achieved an effective enhancement of fracture toughness while maintaining the bending strength. Compared with the monolithic silica, the composite with simultaneous addition of alumina platelets and boron nitride nanosheets had a fracture toughness of 2.23 Mpa·m1/2, increased by approximately 27% (1.75 Mpa·m1/2). The crack deflection and platelet pullout were contributing to enhancement of the fracture toughness. The improved mechanical properties, combined with the intrinsic excellent dielectric and chemical properties, make the silica matrix composites promising wave transparent and thermal protection materials.
Thermal Stability of Fluorescent Chitosan Modified with Heterocyclic Aromatic Dyes
Authors: Bajer Dagmara , Kaczmarek Halina
Published: May 2022

Fluorescent biopolymer derivatives are increasingly used in biology and medicine, but their resistance to heat and UV radiation, which are sterilizing agents, is relatively unknown. In this work, chitosan (CS) modified by three different heterocyclic aromatic dyes based on benzimidazole, benzothiazole, and benzoxazole (assigned as IBm, BTh, and BOx) has been studied. The thermal properties of these CS derivatives have been determined using the Thermogravimetric Analysis coupled with the Fourier Transform Infrared spectroscopy of volatile degradation products. The influence of UV radiation on the thermal resistance of modified, fluorescent chitosan samples was also investigated. Based on the temperature onset as well as the decomposition temperatures at a maximal rate, IBm was found to be more thermally stable than BOx and BTh. However, this dye gave off the most volatile products (mainly water, ammonia, carbon oxides, and carbonyl/ether compounds). The substitution of dyes for chitosan changes its thermal stability slightly. Characteristic decomposition temperatures in modified CS vary by a few degrees (<10 °C) from the virgin sample. Considering the temperatures of the main decomposition stage, CS-BOx turned out to be the most stable. The UV irradiation of chitosan derivatives leads to minor changes in the thermal parameters and a decrease in the number of volatile degradation products. It was concluded that the obtained CS derivatives are characterized by good resistance to heat and UV irradiation, which extends the possibilities of using these innovative materials.
Study of the Influence of the Type of Aging on the Behavior of Delamination of Adhesive Joints in Carbon-Fiber-Reinforced Epoxy Composites
Authors: Vigón Paula , Argüelles Antonio , Mollón Victoria , Lozano Miguel , Bonhomme Jorge , Viña Jaime
Published: May 2022

This study analyzes the behavior under the static delamination and mode-I fracture stress of adhesive joints made on the same composite material with an epoxy matrix and unidirectional carbon fiber reinforcement and two types of adhesives, one epoxy and the other acrylic. Standard DCB tests (for mode-I fracture) were used to quantify the influence on the interlaminar fracture toughness of the type of adhesive used. Both materials were subjected to two different degradation processes, one hygrothermal and the other in a salt-fog chamber. After aging, the mode-I fracture has been evaluated for both materials. From the experimental results obtained, it can be deduced for the epoxy adhesive that exposure to the hygrothermal environment used moderately modifies its behavior against delamination, while its exposure to the saline environment produces a significant loss of its resistance to delamination. For the acrylic adhesive, the hygrothermal exposure causes an improvement in its delamination behavior for all the exposure periods considered, while the saline environment slightly modifies its behavior. There is, therefore, a clear influence of the type of aging on the fracture behavior of both adhesives.
In Vitro and In Vivo Comparison of Bone Growth Characteristics in Additive-Manufactured Porous Titanium, Nonporous Titanium, and Porous Tantalum Interbody Cages
Authors: Wu Meng-Huang , Lee Ming-Hsueh , Wu Christopher , Tsai Pei-I , Hsu Wei-Bin , Huang Shin-I , Lin Tzu-Hung , Yang Kuo-Yi , Chen Chih-Yu , Chen Shih-Hao , Lee Ching-Yu , Huang Tsung-Jen , Tsau Fang-Hei , Li Yen-Yao
Published: May 2022

Autogenous bone grafts are the gold standard for interbody fusion implant materials; however, they have several disadvantages. Tantalum (Ta) and titanium (Ti) are ideal materials for interbody cages because of their biocompatibility, particularly when they are incorporated into a three-dimensional (3D) porous structure. We conducted an in vitro investigation of the cell attachment and osteogenic markers of self-fabricated uniform porous Ti (20%, 40%, 60%, and 80%), nonporous Ti, and porous Ta cages (n = 6) in each group. Cell attachment, osteogenic markers, and alkaline phosphatase (ALP) were measured. An in vivo study was performed using a pig-posterior-instrumented anterior interbody fusion model to compare the porous Ti (60%), nonporous Ti, and porous Ta interbody cages in 12 pigs. Implant migration and subsidence, determined using plain radiographs, were recorded before surgery, immediately after surgery, and at 1, 3, and 6 months after surgery. Harvested implants were assessed for bone ingrowth and attachment. Relative to the 20% and 40% porous Ti cages, the 60% and 80% cages achieved superior cellular migration into cage pores. Among the cages, osteogenic marker and ALP activity levels were the highest in the 60% porous Ti cage, osteocalcin expression was the highest in the nonporous Ti cage, and the 60% porous Ti cage exhibited the lowest subsidence. In conclusion, the designed porous Ti cage is biocompatible and suitable for lumbar interbody fusion surgery and exhibits faster fusion with less subsidence compared with porous Ta and nonporous Ti cages.
Airport Cement Concrete with Ceramic Dust of Increased Thermal Resistance
Authors: Linek Małgorzata
Published: May 2022

The impact of aircraft on airport pavements is varied and closely related to their operational durability. The article presents the impact of the annealing process related to the forced impact of airplanes on airport pavements. The composition of cement concrete with ceramic dust, which is characterized by increased thermal resistance, has been proposed. Two research cycles were programmed, differentiated by the annealing scheme and the way in which the temperature influences the annealing time. Samples stored at a temperature of 20 ± 2 °C were subjected to testing. The tests were carried out for two diagrams: A and B. The first—diagram A—included the continuous impact of the flue gas stream on the samples for a period of 350 min with a test step every 25 min. For the second—diagram B—the samples were alternately heated (1 min) and cooled (15 min). The influence of the proposed pavement mix on changes in the internal structure of cement concrete and the increase in its resistance to high temperatures was determined. In the microstructure of the CC-1 concrete matrix, it was found that there were plate-granular portlandite crystals up to 10 µm in size and ettringite crystals with a length of 8 µm. In the CC-2 concrete, the ettringite crystals were less numerous and had a length of up to 5 µm, there were also continuous contact zones between the aggregate grains and the cement matrix (diagrams A). The alternating annealing/cooling (diagram B) resulted in the ettringite crystals in the CC-1 matrix being up to 10 µm long, and in the CC-2 concrete up to 7 µm long. The contact zone between the aggregate grain and the matrix in CC-2 concrete was continuous, and the microcracks in CC-1 concrete were up to 8 nm. Regardless of the heating diagram, in the surface zone, there were larger microcracks in the CC-1 concrete than in the CC-2 concrete. For diagram A they were 14 µm and 4 µm and for diagram B they were 35 µm and 5 µm, respectively. It was found that concrete with ceramic dust is characterized by a lower and more stable temperature increase. In scheme A, the average temperature increase on the heated surface ranged from 46 °C to 79.5 °C for CC-1 concrete, and from 33.3 °C to 61.3 °C for CC-2 concrete. However, in scheme B, the temperature after 350 heating cycles for CC-1 concrete increased to 129.8 °C, and for CC-2 concrete to 116.6 °C. After the cooling period, the temperature of CC-1 and CC-2 concrete was comparable and amounted to 76.4 C and 76.3 °C, respectively. CC-2 concrete heats to lower values, and favorable changes in internal structure translate into higher strength and durability (after 350 heating cycles according to scheme A, the strength of CC-1 concrete was 67.1 MPa and of CC-2 concrete 83.9 MPa, while in scheme B, respectively, 55.4 MPa for CC-1 and 75 MPa for CC-2).
Multiscale Analogue Modelling of Clinching Process to Investigate Thickness Tolerance and Tool Misalignment
Authors: Nourani Sia A. , Pons Dirk J. , Symons Digby , Zhang Senlin
Published: May 2022

NEED—The effect of dimensional variability of sheet thickness (tolerance) and tool misalignment is poorly understood for the clinching process. Finite element analysis (FEA) is valuable but requires a lot of and is difficult to verify in this situation due to the asymmetrical geometry and nonlinear plasticity. OBJECTIVE—The objective of this work was to determine the effect of thickness tolerance, tool misalignment and sheet placement (top vs. bottom) in the clinching process, by use of analogue modelling with plasticine. METHOD—Experiments used a scaled-up punch and die, with plasticine as the analogue. Thickness tolerances were represented by sheet thicknesses of 11 and 7 mm, 12 and 8 mm, 8 and 12 mm and 13 and 9 mm for upper and lower sheets, respectively. Two types of lubricant were tested between sheets: glycerine and silicone oil. Angular variability was also introduced. Measured parameters were interlock (also called undercut) and neck thickness. Analogue results for deformation were compared with microscopy of metal clinching. FINDINGS—The results reveal that the multiscale analogue model is an efficient tool for studying the effect of dimensional deviation on a clinch joint. Thickness tolerance showed a critical relationship with interlock, namely a reduction to about half that of the nominal, for both maximum and least material conditions. Increased angular misalignment also reduced the interlock. Compared with glycerine, silicone oil tests showed reduced interlock, possibly the result of a lower coefficient of friction. ORIGINALITY—This work demonstrates the usefulness of analogue modelling for exploring process variability in clinching. The results also show that significant effects for sheet placement are ductility, lubricant (friction), thickness of samples and tool misalignment.
Role of Liquid-Phase Amount in Ceramization of Silicone Rubber Composites and Its Controlling
Authors: Pang Haibo , Zhang Shiquan , Pan Lei , Yang Suohui , Zhang Jian , Shi Minxian , Huang Zhixiong , Li Junguo , Shen Qiang
Published: May 2022

The reliable mechanical properties of ceramizable silicone rubber composites during pyrolysis are necessary for their application in the fire-resistant fields. The effects of liquid-phase amount on the mechanical properties of silicone rubber composites are investigated. The results show a positive correlation between the liquid-phase amount and the flexural strength of the residual products pyrolysis below 800 °C. The nano-γ-Al2O3 in the fillers reacts with liquid B2O3 to form aluminum borate above 800 °C, which consumes the liquid phase and strengthens the residual products to a certain extent. Increasing the B2O3 addition and introducing nano-γ-Al2O3 can control the liquid-phase amount in the range of 15% to 30%, which makes the composites have better residual strength and support performance. The residual strength of composites pyrolysis at 500 °C to 1000 °C is higher than 2.50 MPa, and the maximum is up to 18.7 MPa at 1000 °C.
The Uncertainty Propagation for Carbon Atomic Interactions in Graphene under Resonant Vibration Based on Stochastic Finite Element Model
Authors: Shi Jiajia , Chu Liu , Ma Chao , Braun Robin
Published: May 2022

Graphene is one of the most promising two-dimensional nanomaterials with broad applications in many fields. However, the variations and fluctuations in the material and geometrical properties are challenging issues that require more concern. In order to quantify uncertainty and analyze the impacts of uncertainty, a stochastic finite element model (SFEM) is proposed to propagate uncertainty for carbon atomic interactions under resonant vibration. Compared with the conventional truss or beam finite element models, both carbon atoms and carbon covalent bonds are considered by introducing plane elements. In addition, the determined values of the material and geometrical parameters are expanded into the related interval ranges with uniform probability density distributions. Based on the SFEM, the uncertainty propagation is performed by the Monte Carlo stochastic sampling process, and the resonant frequencies of graphene are provided by finite element computation. Furthermore, the correlation coefficients of characteristic parameters are computed based on the database of SFEM. The vibration modes of graphene with the extreme geometrical values are also provided and analyzed. According to the computed results, the minimum and maximum values of the first resonant frequency are 0.2131 and 16.894 THz, respectively, and the variance is 2.5899 THz. The proposed SFEM is an effective method to propagate uncertainty and analyze the impacts of uncertainty in the carbon atomic interactions of graphene. The work in this paper provides an important supplement to the atomic interaction modeling in nanomaterials.
Effect of Sintering Temperature and Polarization on the Dielectric and Electrical Properties of La0.9Sr0.1MnO3 Manganite in Alternating Current
Authors: Hizi Wided , Gassoumi Malek , Rahmouni Hedi , Guesmi Ahlem , Ben Hamadi Naoufel , Dhahri Essebti
Published: May 2022

The electrical characterization ofa La0.9Sr0.1MnO3 compound sintered at 800, 1000 and 1200 °C was investigated by means of the impedance-spectroscopy technique. As the results, the experimental conductivity spectra were explained in terms of the power law. The AC-conductivity study reveals the contributions of different conduction mechanisms. Indeed, the variation in the frequency exponents (‘s1’ and ‘s2’) as a function of the temperature confirms the thermal activation of the conduction process in the system. It proves, equally, that the transport properties are governed by the non-small-polaron-tunneling and the correlated-barrier-hopping mechanisms. Moreover, the values of the frequency exponents increase under the sintering-temperature (TS) effect. Such an evolution may be explained energetically. The jump relaxation model was used to explain the electrical conductivity in the dispersive region, as well as the frequency-exponent values by ionic conductivity. Under electrical polarization with applied DC biases of Vp = 0.1 and 2 V at room temperature, the results show the significant enhancement of the electrical conductivity. In addition, the dielectric study reveals the evident presence of dielectric relaxation. Under the sintering-temperature effect, the dielectric constant increases enormously. Indeed, the temperature dependence of the dielectric constant is well fitted by the modified Curie–Weiss law. Thus, the deduced values of the parameter (γ) confirm the relaxor character and prove the diffuse phase transition of our material. Of note is the high dielectric-permittivity magnitude, which indicates that the material is promising for microelectronic devices.
The Potential Application of Natural Clinoptilolite-Rich Zeolite as Support for Bacterial Community Formation for Wastewater Treatment
Authors: Senila Lacrimioara , Hoaghia Alexandra , Moldovan Ana , Török Iulia Anamaria , Kovacs Dalma , Simedru Dorina , Tomoiag Calin Horea , Senila Marin
Published: May 2022

The aim of this study was to investigate the use of natural zeolite as support for microbial community formation during wastewater treatment. Scanning electron microscopy (SEM), thermal decomposition and differential thermogravimetric curves (TGA/DGT) techniques were used for the physicochemical and structural characterization of zeolites. The chemical characterization of wastewater was performed before and after treatment, after 30 days of using stationary zeolite as support. The chemical composition of wastewater was evaluated in terms of the products of nitrification/denitrification processes. The greatest ammonium (NH4+) adsorption was obtained for wastewater contaminated with different concentrations of ammonium, nitrate and nitrite. The wastewater quality index (WWQI) was determined to assess the effluent quality and the efficiency of the treatment plant used, showing a maximum of 71% quality improvement, thus suggesting that the treated wastewater could be discharged into aquatic environments. After 30 days, NH4+ demonstrated a high removal efficiency (higher than 98%), while NO3+ and NO2+ had a removal efficiency of 70% and 54%, respectively. The removal efficiency for metals was observed as follows (%): Mn > Cd > Cr > Zn > Fe > Ni > Co > Cu > Ba > Pb > Sr. Analysis of the microbial diversity in the zeolite samples indicated that the bacteria are formed due to the existence of nutrients in wastewater which favor their formation. In addition, the zeolite was characterized by SEM and the results indicated that the zeolite acts as an adsorbent for the pollutants and, moreover, as a support material for microbial community formation under optimal conditions. Comparing the two studied zeolites, NZ1 (particle size 1–3 mm) was found to be more suitable for wastewater treatment. Overall, the natural zeolite demonstrated high potential for pollutant removal and biomass support for bacteria community growth in wastewater treatment.
Active Meta-Device for Dual-Transmission Windows with Tunable Angular Dispersion Characteristics
Authors: Li Chenchen , Bai Hui , Yan Mingbao , Wang He , Li Zhiqiang , Wang Wenjie , Wang Jiafu , Qu Shaobo
Published: May 2022

Tailoring electromagnetic properties by meta-devices has aroused great interest with respect to manipulating light. However, the uncertainty of angular dispersion introduced by the incident waves prevents their further applications. Here, we propose a general paradigm for achieving dual-transmission windows while simultaneously eliminating the corresponding angular dispersions by a dynamic manner. The strategy of loading varactor diodes into a plasmonic meta-atom is used. In this way, the blue shifts of angular dispersion can be dynamically compensated by the red shifts introduced by the varactor diodes when driven by bias voltage. As a proof-of-principle, an active meta-atom with varactor diodes is presented. The varactor diodes embedded can independently regulate dual-transmission windows. The test results are consistent with the simulation ones. The presented meta-device is used for intelligent radome, angle-multiplexed communications, and incident-angle-insensitive equipment while providing tunable angular dispersion properties.
Machine and Deep Learning Applications to Mouse Dynamics for Continuous User Authentication
Authors: Siddiqui Nyle , Dave Rushit , Vanamala Mounika , Seliya Naeem
Published: May 2022

Static authentication methods, like passwords, grow increasingly weak with advancements in technology and attack strategies. Continuous authentication has been proposed as a solution, in which users who have gained access to an account are still monitored in order to continuously verify that the user is not an imposter who had access to the user credentials. Mouse dynamics is the behavior of a user’s mouse movements and is a biometric that has shown great promise for continuous authentication schemes. This article builds upon our previous published work by evaluating our dataset of 40 users using three machine learning and three deep learning algorithms. Two evaluation scenarios are considered: binary classifiers are used for user authentication, with the top performer being a 1-dimensional convolutional neural network (1D-CNN) with a peak average test accuracy of 85.73% across the top-10 users. Multi-class classification is also examined using an artificial neural network (ANN) which reaches an astounding peak accuracy of 92.48%, the highest accuracy we have seen for any classifier on this dataset.
Risk of Subsequent Hysterectomy after Expectant Management in the Treatment of Placenta Accreta Spectrum Disorders
Authors: Panaitescu Anca Maria , Peltecu Gheorghe , Botezatu Radu , Iancu George , Gica Nicolae
Published: May 2022

Management strategies for pregnancies with abnormal adherence/invasion of the placenta (placenta accreta spectrum, PAS) vary between centers. Expectant management (EM), defined as leaving the placenta in situ after the delivery of the baby, until its complete decomposition and elimination, has become a potential option for PAS disorders in selected cases, in which the risk of Caesarean hysterectomy is very high. However, expectant management has its own risks and complications. The aim of this study was to describe the rates of subsequent hysterectomy (HT) in patients that underwent EM for the treatment of PAS disorders. We reviewed the literature on the subject and found 12 studies reporting cases of HT after initial intended EM. The studies included 1918 pregnant women diagnosed with PAS, of whom 518 (27.1%) underwent EM. Out of these, 121 (33.2%) required subsequent HT in the 12 months following delivery. The rates of HT after initial EM were very different between the studies, ranging from 0 to 85.7%, reflecting the different characteristics of the patients and different institutional management protocols. Prospective multicenter studies, in which the inclusion criteria and management strategies would be uniform, are needed to better understand the role EM might play in the treatment of PAS disorders.
Identification of Multiple Hub Genes in Acute Kidney Injury after Kidney Transplantation by Bioinformatics Analysis
Authors: Kang Sang-Wook , Kang Sung-Wook , Ban Ju-Yeon , Park Min-Su
Published: May 2022

Background and Objectives: The molecular mechanisms of the development of acute kidney injury (AKI) after kidney transplantation are not yet clear. The aim of this study was to confirm the genes and mechanisms related to AKI after transplantation. Materials and Methods: To investigate potential genetic targets for AKI, an analysis of the gene expression omnibus database was used to identify key genes and pathways. After identification of differentially expressed genes, Kyoto Encyclopedia of Genes and Genome pathway enrichment analyses were performed. We identified the hub genes and established the protein–protein interaction network. Results: Finally, we identified 137 differentially expressed genes (59 upregulated genes and 16 downregulated genes). AKAP12, AMOT, C3AR1, LY96, PIK3AP1, PLCD4, PLCG2, TENM2, TLR2, and TSPAN5 were filtrated by the hub genes related to the development of post-transplant AKI from the Protein–Protein Interaction (PPI) network. Conclusions: This may provide important evidence of the diagnostic and therapeutic biomarker of AKI.
The Roles of Fatty Acids and Apolipoproteins in the Kidneys
Authors: Pan Xiaoyue
Published: May 2022

The kidneys are organs that require energy from the metabolism of fatty acids and glucose; several studies have shown that the kidneys are metabolically active tissues with an estimated energy requirement similar to that of the heart. The kidneys may regulate the normal and pathological function of circulating lipids in the body, and their glomerular filtration barrier prevents large molecules or large lipoprotein particles from being filtered into pre-urine. Given the permeable nature of the kidneys, renal lipid metabolism plays an important role in affecting the rest of the body and the kidneys. Lipid metabolism in the kidneys is important because of the exchange of free fatty acids and apolipoproteins from the peripheral circulation. Apolipoproteins have important roles in the transport and metabolism of lipids within the glomeruli and renal tubules. Indeed, evidence indicates that apolipoproteins have multiple functions in regulating lipid import, transport, synthesis, storage, oxidation and export, and they are important for normal physiological function. Apolipoproteins are also risk factors for several renal diseases; for example, apolipoprotein L polymorphisms induce kidney diseases. Furthermore, renal apolipoprotein gene expression is substantially regulated under various physiological and disease conditions. This review is aimed at describing recent clinical and basic studies on the major roles and functions of apolipoproteins in the kidneys.
A Wideband High-Efficiency GaN MMIC Power Amplifier for Sub-6-GHz Applications
Authors: Hu Liulin , Liao Xuejie , Zhang Fan , Wu Haifeng , Ma Shenglin , Lin Qian , Tang Xiaohong
Published: May 2022

The monolithic microwave integrated circuit (MMIC) power amplifiers serve an essential and critical role in RF transmit/receive (T/R) modules of phased array radar systems, mobile communication systems and satellite systems. Over recent years, there has been an increasing requirement to develop wideband high-efficiency MMIC high power amplifiers (HPAs) to accommodate wideband operation and reduce power consumption. This paper presents a wideband high efficiency MMIC HPA for Sub-6-GHz applications using a 0.25-μm gate-length D-mode GaN/SiC high electron mobility transistor (HEMT) process. The amplifier consists of two stages with two HEMT cells for the driver stage and eight HEMT cells for the power stage. To obtain a flat gain while maintaining the wideband characteristic, a gain equalization technique is employed in the inter-stage matching circuit. Meanwhile, a low-loss output matching network is utilized to ensure high efficiency. The fabricated HPA occupies a compact chip area of 14.35 mm2 including testing pads. Over the frequency range of 2–6 GHz, measured results of this HPA show a saturated continuous wave (CW) output power of 44.4–45.2 dBm, a power added efficiency (PAE) of 35.8–51.3%, a small signal gain of 24–25.5 dB, and maximum input and output return losses of 14.5 and 10 dB, respectively.
Microgripper Using Soft Microactuators for Manipulation of Living Cells
Authors: Kodera Shunnosuke , Watanabe Tomoki , Yokoyama Yoshiyuki , Hayakawa Takeshi
Published: May 2022

We present a microgripper actuated by a soft microactuator for manipulating a single living cell. Soft actuators have attracted attention in recent years because their compliance which can adapt to soft targets. In this study, we propose a microgripper actuated by soft thermoresponsive hydrogels. The thermoresponsive gel swells in water when the temperature is low and shrinks when the temperature is high. Therefore, the microgripper can be driven by controlling the temperature of the thermoresponsive gel. The gels are actuated by irradiating with infrared (IR) laser to localize heating. The actuation characteristics of the gripper were theoretically analyzed and we designed a gripper that gripped a ≈10 µm size cell. Additionally, we succeeded in actuating the fabricated microgripper with laser irradiation and gripping a single living cell.
Analytical and Numerical Solution for Better Positioning in Mines with Potential Extending Application in Space Mining
Authors: Stupar Danijela Ignjatović , Ogrizović Vukan , Rošer Janez , Vižintin Goran
Published: May 2022

Application of new technologies and operational methodologies in mining sector targets to obtain a beneficial outcome in the long term. Instrumentation and monitoring systems for shafts, underground tunneling, storing faculties, etc. are often automated. Implemented systems provide data of mines state, integrated enhanced protection, and early warning solutions. Navigation and positioning in mines are deemed to be unstable in parts of mining tunnels when the external reference points are very far apart, thus significantly increasing the error of the internal network. This paper demonstrates a simulation of an innovative analytical and numerical solution for better positioning in the mines, yielding to increased accuracy of the control points, while reducing the time needed for performing measurements. Based on real tunnel dimensions, different control network configurations are tested. Statistical analysis of simulated environments and virtual measurements, created by combining various instrumentation, confirms cm-level positioning accuracy. The innovative approach to a mine control network design is based on involving fixed-length bars in the network design, gaining in shorter measurements sessions, but keeping homogeneous accuracy throughout the network. The concept is tested on 27 simulated network configurations, combining network points distribution and measurement accuracy of distances and angles. Obtained results and statistical analysis prove that consistent cm-level accuracy can be expected within the network. Extending the concept to space mining, which is becoming an attractive destination for chasing the rare-earth elements (REEs), this methodology will be a spin-off for space exploration mainly applicable in the Lunar lava tube positioning, which are the most secure place to settle the new human life.
A Chemical Separation and Measuring Technique for Titanium Isotopes for Titanium Ores and Iron-Rich Minerals
Authors: Mathur Ryan , Emproto Christopher , Simon Adam C. , Godfrey Linda , Knaack Charles , Vervoort Jeffery D.
Published: May 2022

Ti-isotope fractionation on the most Ti-rich minerals on Earth has not been reported. Therefore, we present a chemical preparation and separation technique for Ti-rich minerals for mineralogic, petrologic, and economic geologic studies. A two-stage ion-exchange column procedure modified from the previous literature is used in the current study to separate Ti from Fe-rich samples, while α-TiO2 does not require chemical separation. Purified solutions in conjunction with solution standards were measured on two different instruments with dry plasma and medium-resolution mode providing mass-dependent results with the lowest errors. 49/47TiOL-Ti for the solution and solids analyzed here demonstrate a range of >5‰ far greater than the whole procedural 1 error of 0.10‰ for a synthetic compound and 0.07‰ for the mineral magnetite; thus, the procedure produces results is resolvable within the current range of measured Ti-isotope fractionation in these minerals.
Daily Consumption of Chocolate Rich in Flavonoids Decreases Cellular Genotoxicity and Improves Biochemical Parameters of Lipid and Glucose Metabolism
Authors: Leyva-Soto Aldo , Chavez-Santoscoy Rocio Alejandra , Lara-Jacobo Linda Ramona , Chavez-Santoscoy Ana Vianey , Gonzalez-Cobian Lina Natalia
Published: May 2022

In recent years, the incidence of atherosclerotic cardiovascular disease, obesity, and diabetes has increased largely worldwide. In the present work, we evaluated the genoprotective effect of the consumption of flavonoids-rich chocolate on 84 young volunteers. Biochemical indicators related to the prevention and treatment of cardiovascular risk and metabolic syndrome were also determined. A randomized, placebo-controlled, double-blind study was performed in the Autonomous University of Baja California. The treatments comprised the daily consumption of either 2 g of dark chocolate containing 70% cocoa, or 2 g of milk chocolate, for 6 months. The total amount of phenolic compounds and flavonoids was determined in both types of chocolate. Anthropometrical and Biochemical parameters were recorded prior to and after the study. The evaluation of the genotoxicity in buccal epithelial cells was performed throughout the duration of the study. Flavonoids from cocoa in dark chocolate significantly prevented DNA damage, and improved the nucleus integrity of cells. This effect could be related to the antioxidant capacity of the dark chocolate that decreased cellular stress. Biochemical parameters (total cholesterol, triglycerides, and LDL-cholesterol level in blood) and anthropometrical parameters (waist circumference) were improved after six months of daily intake of 2 g of dark chocolate with a 70% of cocoa.