Subsequent Bead Research Articles

Mechanical properties improvement of thick multi-pass weld by layered ultrasonic impact treatment

ABSTRACTThe effects of layered ultrasonic impact treatment (LUIT) on the mechanical properties of thick multi-pass weld were investigated. Two 55-mm thick multi-pass welding joints were prepared, one was treated with LUIT, and the other was joined with conventional welding method. Shear-punch test and Charpy impact test were used to examine the mechanical properties of both joints. Results show that LUIT can increase the strength of weld metal (WM), resulting in more uniform shear strength distribution across the treated WM and higher impact toughness of the WM. The mechanical properties improvement of WM attributes to the oxidation of metals induced by ultrasonic impact treatment, which increases the oxygen content in the WM and causes more non-metallic oxide inclusions, and then affects the grain growth behaviour of the subsequent beads, resulting in a fine-grained microstructure and improved strength and toughness of the WM.

Experimentally Calibrated Random Walk of Branched Polymers: A Pragmatic Approach

In order to control the branching behavior of polymers, the comparison of experimental and simulated data is important. The utilization of a nonlattice, self‐avoiding necklace‐bead random walk simulator is reported, which allows for the calculation of radii of gyration r g of polymer molecules with branched structures. The focus is on sensitivity toward short‐chain branches, long‐chain branches (LCBs), and the copolymer composition. Using only two parameters—the size of monomer beads and the minimum angle between three subsequent beads—a fast and reliable parameter fit procedure based on experimental data is described. The procedure is exemplarily shown for copolymers of vinylidene fluoride and hexafluoropropene (HFP) with HFP contents in the copolymer of at most 0.3 and is easily transferable to other polymers that may be analyzed by size‐exclusion chromatography/multiangle laser light scattering close to θ conditions. Applying the Zimm–Stockmayer equation to simulated r g data allows for comparing the “effective” number of LCBs with the number of LCBs given by kinetic simulations. A tool for better estimation of rate coefficients associated with the formation of short‐ and long‐chain branches is provided.image

Whey microbeads as a matrix for the encapsulation and immobilisation of riboflavin and peptides

Whey microbeads manufactured using a cold-set gelation process, have been used to encapsulate bioactives. In this study whey microbeads were used to encapsulate riboflavin using 2 methods. Riboflavin was added to the microbead forming solution however diffusional losses of riboflavin occurred during the subsequent bead preparation. To overcome riboflavin loss, a second approach to ‘load’ whey microbeads by soaking in riboflavin was assessed. Significantly (p⩽0.05) higher concentrations of riboflavin were obtained in ‘loaded’ microbeads (361mg/L) compared to riboflavin added to the microbead forming solution (48mg/L). Riboflavin uptake by the microbeads was shown to be via a partition process. As partitioning is often driven by hydrophobic interactions the uptake of amino acids and peptides of varying hydrophobicities by the microbeads was examined. The % encapsulation increased with increasing molecule hydrophobicity with a maximum of 89% encapsulation. Whey microbeads are well suited to act as sorbents for encapsulation.

Microstructure Analysis on GMAW Additive Manufacturing Parts Constrained by Electromagnetism

A GMAW additive manufacturing process is performed with H08Mn2Si wire to fabricate a cube forming part. A optical microscope was used to observe the cross section aspect of forming part and the structure mechanism has been analysed. The results demonstrate that the forming part structure presents a characteristic that macrostructure is uniform and microstructure changes circularly. The circularly heating pattern of GMAW surfacing forming results in circular microstructure change and preheating of formed bead to subsequent bead and postheating of subsequent bead to formed bead are primary reason. Electromagnetic stirring effect of longitudinal dc magnetic field to molten pool can break dendritic crystal and refine crystal grain, which is in favor of enhancing forming part performance.

Chaperone Probes and Bead-Based Enhancement To Improve the Direct Detection of mRNA Using Silicon Photonic Sensor Arrays

Herein, we describe the utility of chaperone probes and a bead-based signal enhancement strategy for the analysis of full length mRNA transcripts using arrays of silicon photonic microring resonators. Changes in the local refractive index near microring sensors associated with biomolecular binding events are transduced as a shift in the resonant wavelength supported by the cavity, enabling the sensitive analysis of numerous analytes of interest. We employ the sensing platform for both the direct and bead-enhanced detection of three different mRNA transcripts, achieving a dynamic range spanning over 4 orders of magnitude and demonstrating expression profiling capabilities in total RNA extracts from the HL-60 cell line. Small, dual-use DNA chaperone molecules were developed and found to both enhance the binding kinetics of mRNA transcripts by disrupting complex secondary structure and serve as sequence-specific linkers for subsequent bead amplification. Importantly, this approach does not require amplification of the mRNA transcript, thereby allowing for simplified analyses that do not require expensive enzymatic reagents or temperature ramping capabilities associated with RT-PCR-based methods.

溶融溶接を利用した鋳鉄／鋼複合材料の開発

Cast iron with nodular graphite was surface welded on 12mm thick,150mm and 350mm wide,and 600mm long SS400 plates,by self-shielded gas arc welding method. Instead of ordinary preheating,the heat-flows from multiple weld beads were accumulated to raise the temperature of welding zone. For the purpose,the parallel beads were laterally reciprocated at a small bead pitch of 3mm. The effect of welding heat-cycle on the microstructure and mechanical properties of the deposited metal was investigated,changing the reciprocating length, 110mm and 310mm. Main results obtained were as follows;(1) The influence of the heat-flows from preceding and following weld beads on the structure of deposited metals were composed of two major parts. They were the influence of slow cooling,and that of annealing effect on the rapidly-cooled deposited metal. (2) With the short welding heat cycle on the 150mm wide specimen,the molten metal was kept in a temperature range higher than 1500K with a small fluctuation,and cooled slowly resulting bull's-eyes structure with small amount of cementite. (3) With the long heat cycle on the 350mm wide specimen, the deposited metal was rapidly cooled. Following rapid cooling, the temperature of the deposited metal was sharply fluctuated with lower end below 1200K,as the subsequent beads approached and departed,resulting many small graphite nodules in the ferrite matrix. (4) Except the 1st bead, low dilutions resulted from the small bead pitch.

Comparison of mesoscopic phospholipid–water models

In this study we show how a coarse-grained model of a phospholipid can be developed and we study the parameter sets applied to the formation of a coarse-grained dimyristoyl phosphatidyl choline (DMPC) bilayer. We create a model comprising a head group of three hydrophilic beads, to which two hydrophobic tails are connected. From results obtained with molecular dynamics simulations on a single lipid in water, a bond-bending potential between three subsequent beads was added. Using a bead volume of 90 A3, we reproduce the experimental values of the area per lipid and the hydrophobic thickness. There is no linear relation between the repulsion parameter aij and the level of coarse graining. The key factor in the formation of a lipid bilayer is the difference between the water–water and the water–hydrophobic tail repulsion parameters.

Drag force approach to the transport of colloids in unsaturated soils

A drag force approach to the transport of colloids in unsaturated soils is introduced. It is based on film flow which is due to momentum dissipation during porous media flow. Supporting results are from three types of colloid transport experiments: (1) sprinkling of a latex bead and methylene blue suspension in situ on the surface of a forest soil with subsequent bead collection underneath, (2) application of bead suspension to a column of undisturbed soil and purging of retained beads, and (3) application of a suspension with 5 bacteriophages to a different soil column. Relative colloid breakthrough concentrations in relation to the drag forces, P/P0, versus Fd(t)/A, were well pronounced during bead breakthrough, and bead diameters had no significant impact. In contrast, phage breakthrough showed a wide range of behavior. Previous bacteria breakthrough experiments support the approach; however, site‐specific soil properties should also be considered.