High Resistance Research Articles

The Linear Swept Sine Method to Determine the Dispersion Curve of Structural Pavement

Abstract Pavement evaluation must be performed in nondestructive ways. This includes using the multi-channel analysis of surface waves (MASW) method by recording waves detected by multiple sensors from one active source. However, heavy traffic produces noise and reduces the detection quality as the sensor moves further away from the measurement source. We need a pavement evaluation method that is immune to noise. The linear swept-sine method (LSSM) presented in this paper has a very high resistance to noise by using a wide frequency band vibration source to the ground received by a single accelerometer at a small distance. The noise resistance is obtained by applying a tracking filter at the receiver (accelerometer), which accepts the signal with the frequency swept linearly at the same rate as the transmitter. This tracking filter has a low-frequency component equal to the phase delay between the source and the receiver, even when the transmitted source is generated in the high-frequency range. The dispersion curve is calculated and inverted by using the surface wave inversion method to obtain the velocity model below the pavement by calculating the delay for each data segment.

Engineering Characteristics of Concrete Made from Daz Shrub Fibers and Iranshahr Daman River Sediments in the Southeast of Iran in Strengthening Structures Against Earthquakes

The purpose of the present research is the engineering characteristics of concrete made from Daz shrub fibers and Iranshahr Daman river sediments in the southeast of Iran in strengthening structures against earthquakes. Therefore, in order to determine the textural characteristics and composition of sediments of the Daman River, 15 samples of the sediments of this river were collected in separate bags, and then to study, the composition, texture and constituents of these sediments were made into thin sections. The laboratory was transferred. Statistical graphs and parameters of sediments were drawn to determine the average size, frequency and cumulative graphs. Examining the process of texture changes along the river, after drawing the relevant graphs of texture changes and the composition of sediment samples taken from Daman River, shows textural changes. Also, a comparison between single-stranded, two-stranded and three-stranded leaves of Daz shrub was used to increase the strength of concrete, and the results showed that the effect of concrete strength is by changing the number of leaves from one strand. It varied in three fields. The resistance of two strands of Daz leaves was 10.1 MPa, a single strand was 9.5 MPa, and a sample of cylindrical concrete consisting of three strands of Daz leaves was the least resistant, i.e. 5.1 MPa. Therefore, the highest resistance is related to the concrete made of two strands of leaves. DOI: https://doi.org/10.52783/pst.788

EDM-Grinding composite machining and drilling of polycrystalline diamond tool

ABSTRACT Polycrystalline diamond (PCD) is widely used for micro tools due to its high hardness and wear resistance. However, micro PCD tools face challenges in machining with high accuracy and efficiency. Therefore, electrical discharge machining grinding (EDM-grinding) composite machining was proposed. The effects of pulse discharge parameters on surface quality and microhole drilling performance of PCD tool were investigated. The results show that the surface roughness of helix flute and flank face of the fabricated PCD tool were 0.125 µm and 0.158 µm, respectively, as well as the inner wall roughness achieved 0.331 µm after drilling of microhole. The average current displayed a greater effect on the machining quality of PCD tools, with tool breakage in excessive average current. The preferred pulse discharge parameters were determined as an open-circuit voltage of 95 V, an average current of 1400 mA, a pulse width of 400 ns, and a pulse interval of 2000 ns.

Ultrafast One‐Step Synthesis of Garnet‐Type Solid Electrolytes With Modified Surface and Microstructure for Solid‐State Lithium‐Metal Batteries

AbstractGarnet‐type Li6.5La3Zr1.5Ta0.5O12 (LLZTO) solid electrolytes provide the necessary electrochemical stability and ionic conductivity for solid‐state lithium‐metal batteries (SSLMBs). However, their wider application is hindered by their high interfacial resistance with electrodes and a lengthy synthesis process. This study presents the synthesis of densified LLZTO electrolytes using unconventional Li2O and Li2ZrO3 precursors through an ultrafast (≈60 s) Joule heat‐assisted synthesis approach in a single‐step process. The lower sintering temperature of Li2ZrO3 compared to traditional ZrO2 precursor yields LLZTO with larger grains, resulting in enhanced Li+ conductivity (7.0 × 10−4 S cm−1 at 25 °C), reduced electronic conductivity (1.7 × 10−10 S cm−1), and higher density (94.2%). Applying a 52–80 nm Sn:SnF2 coating on the LLZTO surface using a melt‐quenching approach produces a uniform interlayer that chemically converts to Li‐Sn alloy and LiF upon contact with lithium, resulting in a near‐zero interfacial resistance and a critical current density of 4.2 mA cm−2 at 25 °C. The SSLMBs, incorporating Sn:SnF2‐coated LLZTO electrolyte with NMC811 cathode, demonstrate remarkable initial capacity (181.1 mAh g−1) and cycle performance (88.63% capacity retention at 3000th cycle). The results indicate that this approach has the potential to advance the commercial fabrication technology for high‐performance solid electrolytes for SSLMBs.

Effects of different corrugated rolls on the performance of BTW1/Q345R composite plate

Abstract The BTW1/Q345R composite plate not only possesses dual performance advantages of high strength and wear resistance but also contributes to reduced energy consumption and production costs. This paper proposes a novel rolling process based on corrugated rolls for the preparation of wear-resistant steel BTW1/Q345R composite plates.Macroscopic plate shape, microscopic structure, and mechanical properties of the post-rolled wear-resistant steel BTW1/Q345R composite plates are analyzed using techniques such as Electron Backscatter Diffraction (EBSD). The results indicate that the composite plate obtained through rolling with a 3# corrugated roll exhibits a yield strength of 550 MPa, tensile strength of 705 MPa, elongation at break of 17.57%, and shear strength of the composite interface at 242 MPa. Notably, the rolling process with a 3# corrugated roll yields the best combination of tensile mechanical performance and interface bonding performance for the composite plate.

Fabrication and Properties of Superhydrophobic Colored Stainless Steel Surface for Decoration and Anti-Corrosion

A colored superhydrophobic surface on a stainless steel substrate was achieved by means of high temperature oxidation combined with subsequent spraying modification by superhydrophobic nano-silica film. Comprehensive characterizations of the surface were performed in terms of color, morphology, composition, wettability, and corrosion resistance by optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), contact angle, potentiodynamic polarization, and electrochemical impedance spectroscopy measurement. At 400 °C, the surface was pale yellow, gradually turning yellow and then red as the temperature increased. At 700 °C and 800 °C, the surface colors were blue and dark brown, respectively. The samples with oxide films demonstrated lower contact angles, specifically 80.5° ± 2.5 at 400 °C, 79.1° ± 2.8 at 500 °C, and 75.6° ± 3.4 at 600 °C. The polarization resistance measured on the oxidized film formed at 600 °C exceeded 7.93 × 104 Ω·cm2. After spraying the treatment, these colorful surfaces exhibited superhydrophobicity, they were self-cleaning, and they satisfied anti-corrosion properties. The treatment performs as an excellent barrier and exhibits a high corrosion resistance of 4.68 × 106 Ω·cm2. The successful preparation of superhydrophobic colored surfaces offers the possibility of providing stainless steel with both decoration value and self-cleaning function simultaneously by our proposed chromium-free fabrication process.

Natural Selection on Hydroxyapatite Fiber Orientations for Resisting Damage of Enamel

Teeth have excellent mechanical properties, with high wear resistance and excellent fracture resistance. This is due to their well-organized multilevel hierarchical structure. While a number of studies in the last decades have revealed the relationship between tooth structure and mechanical properties, there is still no general agreement on how different orientations of hydroxyapatite (HAp) fibers affect the mechanical properties of enamel. With a scanning electron microscope and nanoindenter, the orientations of HAp fibers and their properties were investigated. HAp fibers have two different orientations: parallel and perpendicular to the surface. Fibers oriented parallel to the surface exhibited higher hardness, elastic modulus and wear resistance. Under applied force, fibers oriented perpendicular to the surface suffered deeper shearing in the protein along the long axis, resulting in lower mechanical properties. Teeth resist damaging fractures by combining hard and soft structures. This study may lead to new insights into how nature selects for tooth structure and provide a theoretical basis for the bioinspired design.

Zero-power infrared switch with two-phase microfluidic flow and a 2D material thermal isolation layer

Wireless sensor nodes (WSNs) play an important role in many fields, including environmental monitoring. However, unattended WSNs face challenges in consuming power continuously even in the absence of useful information, which makes energy supply the bottleneck of WSNs. Here, we realized zero-power infrared switches, which consist of a metasurface and two-phase microfluidic flow. The metasurface can recognize the infrared signal from the target and convert it into heat, which triggers the two-phase microfluidic flow switch. As the target is not present, the switch is turned off. The graphene/MoS2/graphene 2D material heterostructure (thickness <2 nm) demonstrates an exceptionally high thermal resistance of 4.2 K/W due to strong phonon scattering and reduces the heat flow from the metasurface to the supporting substrate, significantly increasing the device sensitivity (the displacement of the two-phase microfluidic flow increases from ~1500 to ~3000 µm). The infrared switch with a pair of symmetric two-phase microfluidic flows can avoid spurious triggering resulting from environmental temperature changes. We realized WSNs with near-zero standby power consumption by integrating the infrared switch, sensors, and wireless communication module. When the target infrared signal appears, the WSNs are woken and show superb visual/auditory sensing performance. This work provides a novel approach for greatly lengthening the lifespan of unattended WSNs.

Amino Acid Decorated Phenanthroline Diimide as Sustainable Hydrophilic Am(III) Masking Agent with High Acid Resistance

Amino Acid Decorated Phenanthroline Diimide as Sustainable Hydrophilic Am(III) Masking Agent with High Acid Resistance

A molecular design strategy to develop all‐organic crosslinked polyetherimide film with high discharged energy density at 150°C

AbstractMiniaturization and lightweight of power systems urgently ask for polymer dielectrics with high discharged energy density at 150°C. Herein, a molecular design strategy is built to prepare new crosslinkable polyetherimide films (PEIDx, x is the molar ratio of dianhydride to amines) through simultaneously improving the polarization degree and reducing the residual polarization. Thermal, mechanical, and dielectric properties of PEIDx improve as x increases. PEID0.92 shows the best integrated performances, especially its discharged energy density (5.46 J cm−3, at 10 Hz and 454 MV m−1) is higher than those of reported polymer dielectrics with discharged energy storage at 150°C, and its charge–discharge efficiency is 80.14%. The outstanding energy storage performance of PEID0.92 is attributed to its unique molecular structure. Specifically, the use of nonplanar and low‐alkaline aliphatic cyclic diamine effectively improves the polarization degree of macromolecules; while the crosslinking of alkynyl groups limits the macromolecular movement, thus ensuring high heat resistance and low residual polarization.

Phytochemical Screening And Antimcrobial Efficacy of Leaf Extract Of Guava (Psidium guajava) On Selected Bacteria

Guava leaf extract has analgesic, anti-inflammatory, antimicrobial, hepato protective and antioxidant activities. The high resistance of bacteria to modern day drugs has led researchers in the pharmaceutical industry to look towards plant-based extracts for solutions. Hence, this studywas aimed at evaluating the phytochemical and antibacterial efficacy of leaf extracts of Psidium guajava (guava) on some selected bacteria. Pure isolates of bacteria gotten from urine of patients in Charis Rhema Research and Diagnostic Laboratory were used in the study. Extracts from the leaves of Psidium guajava were tested for presence of phytochemicals. Separation of active components of the extracts was one using Chromatographic technique. The antibacterial activityof Psidium guajava leaves was determined using agar diffusion bioassay. Phenols were present at all concentrations (100, 80 and 60mg). The study discovered a significant relationship between extract concentration and the zones of inhibition at 60% N-hexane/40% methanol for Klebsiellasp., and 0.0% N-hexane/100% methanol for S. aureus. Flavonoids, tannins, saponins and phenols were the active compounds in guava that helped in the inhibition of growth on the sampled isolates. Methanol and N-hexane extracts of guava can be used as potent medicines for inhibitingthe growth of Klebsiella and Staphylococcus aureus.

Improving the Performance of the Machining Process by Using Ultra‐Advanced Tools in a Clean Turning of Inconel 686 Using the Minimum Quantity Lubrication Method

ABSTRACTThe high tensile strength and high resistance of nickel‐based superalloy 686 against high temperatures and corrosion rates have made it a widely used in important applications such as the aerospace industry, high pollution‐ and corrosion‐resistance equipment manufacturing and petrochemical industry. Therefore, the machining of this advanced alloy with its unique properties is extremely important and can be challenging. Significant increase in input parameters levels, reduction of machining costs, improvement of surface and subsurface properties and clean production are among the issues that should be considered in dealing with Inconel 686 turning operations. Simultaneous application of advanced tools such as polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) and optimised minimum quantity lubrication (MQL) method and evaluating the results obtained with a wide range of output parameters related to machining process performance and tribological properties can be proposed as an innovation and a solution to this problem in this article. This study analyses several output parameters with different speeds and feeds to evaluate the effect of cutting insert type on machining process performance and tribological properties. The output parameters include tool wear, residual stress, cutting zone temperature, surface smoothness, machining forces and workpiece surface defects. The results indicated that using the optimised MQL method reduces the size of lubricant droplets and increases the surface covered by cooling. With these changes, the performance of the machining process and the parameters related to the surface integrity increase significantly. Among the parameters associated with the performance of the machining process, the PCD tool reduces the cutting zone temperature by 23%, the tool wear by 19% and the machining forces by 18% compared to the PCBN tool. In the parameters related to surface integrity, this method reduces the residual stress by 19% and the surface roughness by 9% compared to the PCBN tool. From the production index perspective, the PCD tool can significantly increase the cutting speed and feed rate, reducing production time and costs.

Overexpression of Two Odorant Binding Proteins Confers Chlorpyrifos Resistance in the Green Peach Aphid Myzus persicae.

The green peach aphid, Myzus persicae, is a worldwide agricultural pest. Chlorpyrifos has been widely used to control M. persicae for decades, thus leading to a high resistance to chlorpyrifos. Recent studies have found that insect odorant binding proteins (OBPs) play essential roles in insecticide resistance. However, the potential resistance mechanism underlying the cross-link between aphid OBPs and chlorpyrifos remains unclear. In this study, two OBPs (MperOBP3 and MperOBP7) were found overexpressed in M. persicae chlorpyrifos-resistant strains (CRR) compared to chlorpyrifos-sensitive strains (CSS); furthermore, chlorpyrifos can significantly induce the expression of both OBPs. An in vitro binding assay indicated that both OBPs strongly bind with chlorpyrifos; an in vivo RNAi and toxicity bioassay confirmed silencing either of the two OBPs can increase the susceptibility of aphids to chlorpyrifos, suggesting that overexpression of MperOBP3 and MperOBP7 contributes to the development of resistance of M. persicae to chlorpyrifos. Our findings provide novel insights into insect OBPs-mediated resistance mechanisms.

Resistance to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides in Lolium multiflorum Lam. populations of Argentina.

Italian ryegrass (Lolium multiflorum Lam.) is one of the most troublesome grass weeds in Argentina. The extensive and repetitive use of acetyl-CoA carboxylase (ACCase)-inhibiting herbicides has induced resistance in this weed species. The objectives of this study were to quantify the resistance levels to ACCase-inhibiting herbicides in two resistant populations and to identify the target-site mutations associated with their resistance. Two resistant Italian ryegrass populations, Roldán and H2, were studied. Roldán was a suspected haloxyfop-resistant population, located in a wheat field from Santa Fe province with a history of ACCase-inhibiting herbicide use. The H2 population was obtained from the susceptible Hernandarias population (H0) after two cycles of selection with the herbicide quizalofop-ethyl. Whole-plant dose-response assays revealed that the resistant populations exhibited a high resistance to haloxyfop, with resistance factors (RF) exceeding 97-fold. Additionally, both populations showed a moderate resistance to pinoxaden (RF > 7), while maintaining susceptibility to clethodim. Partial chloroplastic ACCase sequences revealed isoleucine-to-asparagine substitution at position 2041 (Ile-2041-Asn) in both resistant populations. This work provides a better understanding of cross-resistance to ACCase-inhibiting herbicides in L. multiflorum populations and represents the first report of the target-site mutation Ile-2041-Asn conferring resistance in populations from Argentina. © 2024 Society of Chemical Industry.

Tailoring microstructure in a soft-magnetic Fe-based amorphous-nanocrystalline alloy for high resistivity according to electrical percolation threshold

Superior soft-magnetic materials are necessary for the development of modern magnetic devices with energy-saving and high-power density requirements. However, improving the magnetism by nanocrystallization always brings about the sacrifice of resistivity, presenting a common trade-off in Fe-based amorphous-nanocrystalline alloys. Here, the comprehensive merits of both superior soft-magnetic properties (high saturation magnetization of 1.81 T and low coercivity of 3.8 A/m) and high resistivity of 117.2 μΩ·cm were obtained by precisely tailoring amorphous-nanocrystalline microstructure close to electrical percolation threshold for a Fe82.5B12P2C1Cu0.5Co2 amorphous alloy. The soft-magnetic properties are attributed to the low magnetic anisotropy stemming from high nuclei number density and ultrafine nanocrystalline grains of 9.2 nm. The high resistivity is associated with the electrical percolation behavior with a nanocrystalline volume threshold of 14.8 % in the composite alloy. The results provide an effective strategy to overcome the trade-off in traditional amorphous-nanocrystalline alloys, significant for applications in high-frequency, high-power, and energy-saving devices.

Effect of scanning speeds on microstructure evolution and properties of 70Cr8Ni2Y coatings by direct laser deposition

Abstract The 70Cr8Ni2Y coatings were prepared by direct laser deposition (DLD) with different scanning speeds. The microstructure evolution and the relationship between microstructure and properties of the coatings were studied. The results demonstrated that the microstructure of DLD 70Cr8Ni2Y coatings was martensite, and the phases were α′ (Fe-Cr) and γ-Fe (Fe-Ni). With the increased of scanning speed, the martensite size decreased from 5.42 ± 0.04 μm to 4.42 ± 0.01 μm and 3.20 ± 0.02 μm. When the scanning speed was 20 mm s−1, the fabricated coating displayed the highest average microhardness (883 ± 37 HV) and the lowest mass wear rate (0.061 mg mm−1) without pores. The combined strengthening effect of fine grain strengthening and solid solution strengthening, as well as good formability, were the fundamental reasons for the high hardness and wear resistance of the coating. The results of this study can provide an experimental basis for the DLD alloy coatings with high hardness and wear resistance.

Design and Calculation of Products from Composite Materials Using Software

This article analyzes six types of composite pipes that are good replacements for corrosive steel and metal pipes for oil, gas, and water. The analysis of the six samples of composite pipes was done using the software program Hoffman Engineering, which is intended for the design and calculation of various types of products made of composite materials. For the analysis of the six composite pipes, the same diameter and the same length were taken, and variable parameters are: the type of material from which the composite pipes are made (carbon/epoxy, carbon-glass/epoxy and glass/epoxy), and the angle of winding of the fibers (10º and 90º degrees). Using the Hoffman Engineering software package, an analysis of the durability of the six differently designed composite pipes at high internal pressure was performed. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. Composite pipes obtained with a fiber winding angle of 90º have twice the internal pressure resistance compared to composite pipes obtained with a fiber winding angle of 10º. Composite pipes based on carbon fibers have the highest resistance to internal pressure, then composite pipes based on hybrid materials (glass and carbon fibers) and finally composite pipes based on glass fibers. Finally, a comparison was made with the obtained laboratory results for the same composite pipes. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. The composite pipes obtained by this process are durable and resistant to very high pressures.

Exploring Nb[sbnd]Si based alloys with excellent fracture toughness and oxidation resistance

The main objective of this paper is to give a comprehensive discussion of the fracture toughness and oxidation resistance of Nb-16Si-20Ti-3Al-5Cr-xSn-yZr (x = 0.5, 1.5; y = 2, 4, 6) alloys, based on experimental evidence, phase formation and diffusion theory. Results demonstrate that the microstructure of Sn0.5Zr2 and Sn1.5Zr2 alloys consist of Nbss and α-Nb5Si3, and the other four alloys are composed of Nbss, α-Nb5Si3 and γ-Nb5Si3. At the same time, the area fraction of γ-Nb5Si3 increases with the increase of Zr content. The coarsening of silicides increases with the addition of Sn. The KQ value of the Sn0.5Zr4 alloy reaches the highest with the mean of 12.64 MPa·m1/2. After oxidation at 800 °C for 24 h, Sn0.5Zr4 alloy alloy did not undergo pest oxidation. Sn0.5Zr4 alloy forms a continuous and dense TiO2 oxide layer oxidized at 1200 °C, which makes it have the best high temperature oxidation resistance. Sn0.5Zr4 alloy has excellent fracture toughness, medium temperature and high temperature oxidation resistance.

Staged dendrite suppression for high safe and stable lithium-sulfur batteries

The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries. Herein, we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator. The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition, but also reduce the formation of dendrite during early deposition stage. Most importantly, under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current, the high ductility and robust puncture resistance (145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite. The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA with a polarization voltage of only 29.3 mV. Additionally, the negative charged layer serves as a physical barrier blocking lithium polysulfide ions, effectively mitigating capacity attenuation. The improved cells achieved a capacity decay of only 0.042% per cycle after 700 cycles at 3 C, demonstrating effective suppression of dendrite growth and capacity attenuation, showing promising prospect.

Anisotropic ferroelectric-shaped hysteresis loop and colossal permittivity in thermally treated rutile TiO2 single crystals

Space charge polarization is an unavoidable phenomenon in electronic components that leads to deterioration of electrical response. Hence manipulation and utilization of space charge polarization to improve electrical properties is a phenomenal task. In the present study, heating treatment produces oxygen vacancies, resulting in the crystal structures (i.e., modulated structure and intergrowth structure) and band gap are anisotropic, which in turn leads to anisotropic nonlinear polarization behavior and colossal permittivity. Quantitative analysis of the atomic-scale structure confirms the modulated structure and intergrowth structure are anisotropic. A modulated structure along a axis of rutile TiO2 with a width of six times that of a rutile crystal cell a is constructed through an intergrowth structure between rutile and srilankite TiO2 phases in rutile TiO2 single crystals, wherein space charges at the intergrowth structure give rise to ferroelectric-shaped hysteresis in heated TiO2 single crystals along [001] direction. Impedance spectra display three kinds of space charge polarizations (modulated structure, intergrowth structure, and electrode non-ohmic contact) contribute to the colossal permittivity along [001] direction. The space charge polarizations contribute to a colossal permittivity (∼45,000), high resistivity (∼1010 Ω cm), and ferroelectric-shaped P-E loop (remanent polarization: ∼17.1 μC/cm2, coercive field: ∼4.3 kV/cm) in the heated TiO2 single crystal along [001] direction, while a linear polarization behavior and permittivity value of 120 are obtained along [100] direction. The findings provide guidance for the utilization of space charge polarization in dielectric materials.