Study on Microstructure and Properties of Welded Joints with Low Strength Backing Layer for WELDOX960

The welding of WELDOX960 ultra-high strength steel must consider not only the strength but also the toughness of the welding zone. In this paper, a new welding process with low strength matching backing layer is studied, that is, we choose ER50-6 wire for backing welding, use T union gm120 wire for MAG welding filling, and complete the cover welding. We prepared two groups of welding samples of ER50-6 wire backing welding and T union gm120 wire backing welding. Then we test the samples by optical metallography, tensile test, impact test and hardness test. The results show that the properties of the two kinds of backing weld can meet the requirements. The basic structure of the weld outside the backing layer of the two welding methods is similar, which are acicular ferrite and carbide. Using ER50-6 welding wire as backing, the microstructure of the weld is uniform and fine ferrite grain and a small amount of pearlite. Using T union GM120 high strength steel as backing, the microstructure of the weld is acicular ferrite and carbide. The toughness of ER50-6 is higher than that of T union GM120, and the hardness is lower than that of T union GM120.The research results have been successfully applied to the welding of large tonnage truck crane boom, and the enterprise has achieved high economic benefits.

A Fluidics-Based Double Flexural Membrane Piezoelectric Micromachined Ultrasonic Transducer (PMUT) for Wide-Bandwidth Underwater Acoustic Applications

In acoustic receiver design, the receiving sensitivity and bandwidth are two primary parameters that determine the performance of a device. The trade-off between sensitivity and bandwidth makes the design very challenging, meaning it needs to be fine-tuned to suit specific applications. The ability to design a PMUT with high receiving sensitivity and a wide bandwidth is crucial to allow a wide spectrum of transmitted frequencies to be efficiently received. This paper presents a novel structure involving a double flexural membrane with a fluidic backing layer based on an in-plane polarization mode to optimize both the receiving sensitivity and frequency bandwidth for medium-range underwater acoustic applications. In this structure, the membrane material and electrode configuration are optimized to produce good receiving sensitivity. Simultaneously, a fluidic backing layer is introduced into the double flexural membrane to increase the bandwidth. Several piezoelectric membrane materials and various electrode dimensions were simulated using finite element analysis (FEA) techniques to study the receiving performance of the proposed structure. The final structure was then fabricated based on the findings from the simulation work. The pulse–echo experimental method was used to characterize and verify the performance of the proposed device. The proposed structure was found to have an improved bandwidth of 56.6% with a receiving sensitivity of −1.8864 dB rel 1 V µPa. For the proposed device, the resonance frequency and center frequency were 600 and 662.5 kHz, respectively, indicating its suitability for the targeted frequency range.

An Improved Equivalent Circuit Simulation of High Frequency Ultrasound Transducer

The equivalent circuit simulation plays an important role in the design of ultrasound transducer. However, the existing methods are difficult to achieve the effect of matching and backing layer, and not able to accurately simulate the transducer with cable. Especially in the application of high frequency ultrasound, the long cable has a great influence on the performance of the transducer. To overcome these limitations, this paper proposed an improved equivalent circuit method, which combined Leach model and transmission line model. It can realize the complete simulation of ultrasound transducer with a long cable, matching layer, and backing layer in PSPICE circuit simulation software when the parameters were measured. Its principles were briefly introduced, and ultrasound transducers with different frequencies (12 and 20 MHz), different matching layers, and different cable lengths (0.5–2.5 m) were designed and fabricated to verify the effectiveness of the method, which is also compared with the traditional KLM method using PiezoCAD. The experiment results showed that the long cable, matching layer, and backing layer have a significant impact on the performance of high frequency ultrasound transducers, and this proposed method has good agreement with these results. Moreover, for the simulation of the complete transducer, the effect of this method is better than KLM model. Besides, this method does not need to know the specific equivalent circuit of matching, backing layer, or cable wire, it can accurately predict the impedance and phase of the transducer through the material parameters, which is very helpful for the material selection and optimization of subsequent transducer design and fabrication. The study indicates that this improved equivalent circuit method is suitable to be applied in the general circuit simulation software and provides strong support for the high frequency transducer and system design.

Bone-adhesive barrier membranes based on alendronate-functionalized poly(2-oxazoline)s

Novel bone-adhesive barrier membranes were successfully developed using a solvent-free approach by combining an occlusive polyester backing layer with a gelatin carrier impregnated with calcium-binding alendronate-functionalized poly(2-oxazoline)s.

Dry Hydrogen Production in a Tandem Critical Raw Material-Free Water Photoelectrolysis Cell Using a Hydrophobic Gas-Diffusion Backing Layer

A photoelectrochemical tandem cell (PEC) based on a cathodic hydrophobic gas-diffusion backing layer was developed to produce dry hydrogen from solar driven water splitting. The cell consisted of low cost and non-critical raw materials (CRMs). A relatively high-energy gap (2.1 eV) hematite-based photoanode and a low energy gap (1.2 eV) cupric oxide photocathode were deposited on a fluorine-doped tin oxide glass (FTO) and a hydrophobic carbonaceous substrate, respectively. The cell was illuminated from the anode. The electrolyte separator consisted of a transparent hydrophilic anionic solid polymer membrane allowing higher wavelengths not absorbed by the photoanode to be transmitted to the photocathode. To enhance the oxygen evolution rate, a NiFeOX surface promoter was deposited on the anodic semiconductor surface. To investigate the role of the cathodic backing layer, waterproofing and electrical conductivity properties were studied. Two different porous carbonaceous gas diffusion layers were tested (Spectracarb® and Sigracet®). These were also subjected to additional hydrophobisation procedures. The Sigracet 35BC® showed appropriate ex-situ properties for various wettability grades and it was selected as a cathodic substrate for the PEC. The enthalpic and throughput efficiency characteristics were determined, and the results compared to a conventional FTO glass-based cathode substrate. A throughput efficiency of 2% was achieved for the cell based on the hydrophobic backing layer, under a voltage bias of about 0.6 V, compared to 1% for the conventional cell. For the best configuration, an endurance test was carried out under operative conditions. The cells were electrochemically characterised by linear polarisation tests and impedance spectroscopy measurements. X-Ray Diffraction (XRD) patterns and Scanning Electron Microscopy (SEM) micrographs were analysed to assess the structure and morphology of the investigated materials.

A Semi-Dissolving Microneedle Patch Incorporating TEMPO-Oxidized Bacterial Cellulose Nanofibers for Enhanced Transdermal Delivery

Although dissolving microneedles have garnered considerable attention as transdermal delivery tools, insufficient drug loading remains a challenge owing to their small dimension. Herein, we report a one-step process of synthesizing semi-dissolving microneedle (SDMN) patches that enable effective transdermal drug delivery without loading drugs themselves by introducing TEMPO-oxidized bacterial cellulose nanofibers (TOBCNs), which are well dispersed, while retaining their unique properties in the aqueous phase. The SDMN patch fabricated by the micro-molding of a TOBCN/hydrophilic biopolymer mixture had a two-layer structure comprising a water-soluble needle layer and a TOBCN-containing insoluble backing layer. Moreover, the SDMN patch, which had a hole in the backing layer where TOBCNs are distributed uniformly, could offer novel advantages for the delivery of large quantities of active ingredients. In vitro permeation analysis confirmed that TOBCNs with high water absorption capacity could serve as drug reservoirs. Upon SDMN insertion and the application of drug aqueous solution through the drug inlet hole, the TOBCNs rapidly absorbed the solution and supplied it to the needle layer. Simultaneously, the needle layer dissolved in body fluids and the drug solution to form micro-channels, which enabled the delivery of larger quantities of drugs to the skin compared to that enabled by solution application alone.

Variations of graphene nanotube membrane support layer in outlet flux of PAFO system

The PAFO system is a solution in the desalination of seawater using a hydraulic pressure of 5 bar, which competes with the FO system (direct osmosis). The project includes four stages of pilot construction, entrainment detection, graphene nanotube membrane synthesis and, finally, efficiency determination and outflow modeling of the PAFO system. High Flux is the most important parameter of the system test for practical application. According to the results, the highest flow of current (120 l / m2.hr) was calculated at the osmotic pressure of 55, indicating a 50% increase in the flow of water with KOH fertilizer as entrainment solution and membrane of low thickness backing layer. Outflow values were calculated using theoretical modeling (MATLAB software). The results show the consistency of the outflow with the flow of the proposed chi model.