Multiple Rolling Research Articles

Multiple sealed primers-mediated rolling circle amplification strategy for sensitive and specific detection of DNA methyltransferase activity

DNA methyltransferase (MTase) aberrant expression has a close relationship to tumorigenesis. DNA MTase activity detection is of great importance to its biomedical research and theranostics study. Here, multiple sealed primers-mediated rolling circle amplification (RCA) strategy is developed for sensitively and specifically detecting DNA MTase activity. The DNA probe has a folded, double-loop structure that seals multiple primers. First, in the presence of DNA MTase, the DNA probe is methylated, which then gets cleaved by the restriction endonuclease and breaks into multiple DNA oligonucleotide fragments. Second, each DNA oligonucleotide fragment acts as an independent primer for triggering RCA reaction respectively, producing long DNA strands that contain several interval G-quadruplexes. Finally, copious of G-quadruplexes are obtained, which bind N-methylmesoporphyrin IX (NMM) to generate significantly enhanced fluorescence. When DNA MTase is absent or inactive, the DNA probe is stable and cannot release the primers for RCA reaction. In the proposed strategy, the action of DNA MTase on one DNA probe is converted to the multiple amplifications triggered by multiple released primers. The detection limit for Dam MTase is down to 0.0085 U/mL, and the target MTase can be well discriminated from its MTases analogues. The method is utilized in screening of Dam MTase inhibitors and analyzing of spiked Dam MTase in biological samples. The results suggest that the strategy may provide a promising tool for DNA MTase activity detection in biomedical research and cancer theranostics.

Strain parameters at hot rolling of aluminum strips reinforced with steel netting

This experiment studied the strain parameters of rolling an aluminum matrix when wire netting is inserted between aluminum layers. During the experiment, two types of stainless steel fabric netting oriented parallel and diagonal to the rolling axis were placed between two aluminum strips and rolled. Multiple rolling processes were performed in which the temperature and pressure on the material were varied to produce bonding of matrix layers. During the study, the following main investigations were made: strain on areas of longitudinal and transverse cross sections of the composite was measured; stretching and ovalization of net wiring and changes in the net cell angles were determined; mechanical properties of composites along the rolling direction were tested. The main contradiction resulting from this experiment was as follows: the contact pressure required for the bonding of aluminum layers produces extreme tensile strain on the inserted net wires, reducing the mechanical properties of the reinforcing net and thus reducing properties of the entire composite. Optimal results in the longitudinal tension tests were achieved by using strips with diagonally oriented net-reinforcement.

Computing MDR-Game with Applications to Real Data

Originally developed for probability and statistic purposes, Multiple Dice Rolling (MDR) game turns out to be useful for many other applications such as complex biological systems and medical research. It has been mainly used to estimate system states that cannot be observed directly. MDR game is affected by noise and fluctuations. It is widely agreed that noise in dynamic systems is captured by using the available computational and experimental technics, which provide information on the dynamics, size and entropy. Recently, computational advances have used algorithmic strategies and focused on stochastic accuracy to predict noise level in a given systems. It is known that experimental techniques can fully characterized the noise pattern and in some cases predicted relatively good outcomes for the MDR game. In this research, we developed a stochastic theory based on the MDR game and applied real data from to the Ciona and Beer-Tavazoie datasets. We found that the Ciona data (cell biometry) was relatively stable and the Beer-Tavazoie data (gene expression) was noisy. These facts support the well-known biologists’ theories that “cells are stable, but genes which are components of cells are unstable”. Furthermore, we have, for the first time, demonstrated quantitatively the molecular biology dogma. This result can be further developed in a novel direction to further understand the disease prediction, control and aging monitoring at the molecular and genetic levels.

Structure Amorphization and Mechanical Properties of Nanolaminates of the Copper–Niobium System During High-Pressure Torsion

The results of investigation of structural transformations and mechanical behavior of nanolaminates are reported, which were manufactured by multiple rolling of alternating layers of copper and niobium, followed by high-pressure torsion in the Bridgeman chamber. A detailed analysis of structure alteration of the material under study is performed by the high-resolution TEM methods. The changes in the value of microhardness in three dimensions (3D) are investigated during variation of the degree of straining of nanolaminates in the course of their torsion. A phenomenon of structure amorphization and a sharp increase in strength characteristics are revealed.

Optimization Scheduling Method for Power Systems Considering Optimal Wind Power Intervals

Wind power intervals with different confidence levels have an impact on both the economic cost and risk of dispatch plans for power systems with wind power integration. The higher the confidence level, the greater the bandwidth of corresponding intervals. Thus, more reserves are needed, resulting in higher economic cost but less risk. In order to balance the economic cost and risk, a unit commitment model based on the optimal wind power confidence level is proposed. There are definite integral terms in the objective function of the model, and both the integrand function and integral upper/lower bound contain decision variables, which makes it difficult to solve this problem. The objective function is linearized and solved by discretizing the wind power probability density function and using auxiliary variables. On the basis, a rolling dispatching model considering the dynamic regulation costs among multiple rolling plans is established. In addition to balancing economic cost and risk, it can help to avoid repeated regulations among different rolling plans. Simulations are carried on a 10-units system and a 118-bus system to verify the effectiveness of the proposed models.

Enhanced Mechanical Properties of 316L Stainless Steel Prepared by Aluminothermic Reaction Subjected to Multiple Warm Rolling

Large dimensional bulk 316L stainless steels were prepared by aluminothermic reaction method and rolled at 973 K (700 °C) with different deformation, the microstructures evolution and mechanical properties were characterized in detail. The results showed that the microstructure of casting steel consists of nanocrystalline/submicrocrystalline/microcrystalline austenite and submicrocrystalline ferrite. After rolling to thickness reduction of 30, 50 and 70%, the submicrocrystalline austenite grains were crushed and dispersed more uniformly in the matrix of the steel, the grain size of submicrocrystalline austenite decreased from 246 to 136 nm. The mechanical properties of the rolled steels were significantly enhanced, with the thickness reduction increased from 30 to 70%, the tensile strength increased from 632 to 824 MPa, the yield strength increased from 425 to 615 MPa, and the elongation increased from 11 to 24%. After rolling to thickness reduction of 70%, the optimized combination of high strength and high ductility was obtained.

Nanocrystal formation in Al- and Ti-based amorphous alloys at deformation

The effect of deformation type on structural changes in Al- and Ti-based amorphous alloys has been studied using the methods of X-ray diffraction, scanning and transmission electron microscopy. The high pressure torsion and multiple rolling methods were chosen for the deformation. It is shown that under deformation by high pressure torsion and multiple rolling methods a large number of shear bands are formed on the sample surface. Although the bands density is roughly equal, the fraction of the nanocrystalline phase forming during deformation in the case of high pressure torsion is greater than that under multiple rolling deformation. The number of shear bands and the fraction of the nanocrystalline phase decrease as the distance from the sample surface increases.

A simple fluorescence biosensing strategy for ultrasensitive detection of the BCR-ABL1 fusion gene based on a DNA machine and multiple primer-like rolling circle amplification.

A one-step, rapid fluorescence biosensing method has been developed for ultrasensitive detection of the BCR-ABL1 fusion gene based on a polymerase/nicking endonuclease DNA machine and multiple primer-like rolling circle amplification (RCA). In the strategy, the BCR-ABL1 fusion gene can be specifically identified by using a dual probe to form a three-way junction structure (3-WJ). Then the 3-WJ based DNA machine is driven by polymerase and nicking endonuclease to generate a large number of triggers, initiating a downstream RCA reaction. The introduction of two nicking endonuclease recognition sites into a circular DNA template makes RCA occur in a multiple primer-like manner, achieving exponential growth of the signal. Benefiting from the cascade amplification, the developed method generates a wide linear response from 10 fM to 1 nM with a low detection limit of 5.52 fM. In addition, the one-step operation allows the assay to be completed within 60 min and acceptable recovery is obtained in complex samples. These merits endow the biosensing strategy with certain potential for the clinical diagnosis and scientific research of the BCR-ABL1 fusion gene.

Strain dependence of diffusion in Zr-based bulk amorphous alloy

We evaluated the effect of strain on the diffusion process of amorphous alloys related to the strain mode in both as-cast and plastically deformed Zr-based bulk amorphous alloy. Experimental investigations of the diffusion process and the elemental distributions in the amorphous alloy were performed by secondary ion mass spectrometry after annealing at 523 K following 30% plastic deformation by multiple cold rolling. Mathematical modeling analyses show an inhomogeneous sequence of the diffusion process by effective strain. The compressive strain near the surface of the deformed amorphous alloy retards ∼13.7% of the diffusion process compared to the as-cast amorphous alloy. The combined experimental and mathematical analyses results reveal that the diffusion process of bulk amorphous alloys can be changed by strain variation and can be adjusted by controlling the effective strain during deformation.

Structure and mechanical properties of a two-layered material produced by the E-beam surfacing of Ta and Nb on the titanium base after multiple rolling

The study has been conducted in line with the current approach to investigation of materials obtained by considerably deep surface alloying of the titanium substrate with Ta, Nb, and Zr. The thickness of the resulting alloyed layer was equal to 2 mm. The coating was formed through weld deposition of a powder with the use of a high-voltage electron beam in the air. It has been lately demonstrated that manufactured such a way alloyed layers possess corrosion resistance which is significantly higher than the resistance of titanium substrates. It has already been shown that such two-layered materials are weldable. The study objective is to investigate the feasibility of rolling for necking the sheets with the Ti-Ta-Nb anticorrosion coating with further fourfold decrease in their thickness. The research is also aimed at investigation of the material properties after rolling. Anticorrosion layers were formed both on CP-titanium and on VT14 (Ti-4Al-3Mo–1 V) durable titanium alloy. The results of chemical composition determination, structure examination, X-ray phase analysis and mechanical properties observations (including bending properties of the alloyed layers) are presented in the paper. The combination of welding, rolling, and bending enables the manufacture of corrosion-resistant vessels and process pipes which are made from the developed material and find technological application.

New Prospective on Multiple Dice Rolling Game and Its Statistical Implications

We present a mathematical formulation of the Multiple Dice Rolling (MDR) game and develop an adaptive computational algorithm to simulate such game over time. We use an extended version of the well-known Chapman-Kolmogorov Equations (CKEs) to model the state transition of the probability mass function of each side of the dice during the game and represent the time-dependent propensity of the game by a simple regression process, which enable to capture the change in the expectation over time. Furthermore, we perform a quantitative analysis on the outcome of the game in a framework of Average Probability Value (APV) of appearance of a side of the dice over trials. The power of our approach is demonstrated. Our results also suggest that in the MDR game, the APV of appearance of a side of a dice can be appropriately predicted independently of the number of sides and trials.

Enhancing Strength of Nanolaminate 1045 Steel Prepared by Aluminothermic Reaction through Multiple Warm Rolling

Large dimensional bulk 1045 carbon steel with nanolaminate pearlite is prepared by aluminothermic reaction casting method. The steel is rolled at 873 K with different thickness reduction. Microstructures evolution and mechanical properties are characterized in detail. The results show that the nanolaminate cementites are crushed with the increase of thickness reduction, the dislocation density increases, meanwhile the tensile strength is improved greatly. The rolled steels possess the key combination of three characteristics, namely, high density dislocation, nanolamination, and second‐phase particles. When the thickness reduction is 60%, most of the lamellar cementites are crushed to globular particles, the tensile strength reaches 719 MPa, and the elongation is 14%. It provides a guidance for all high strength alloy design efforts by this route.

Unusual isothermal multimerization and amplification by the strand-displacing DNA polymerases with reverse transcription activities

AbstarctExisting isothermal nucleic acid amplification (INAA) relying on the strand displacement activity of DNA polymerase usually requires at least two primers. However, in this paper, we report an unusual isothermal multimerization and amplification (UIMA) which only needs one primer and is efficiently initiated by the strand-displacing DNA polymerases with reverse transcription activities. On electrophoresis, the products of UIMA present a cascade-shape band and they are confirmed to be multimeric DNAs with repeated target sequences. In contrast to current methods, UIMA is simple to product multimeric DNA, due to the independent of multiple primers and rolling circle structures. Through assaying the synthesized single-stranded DNA targets, UIMA performs high sensitivity and specificity, as well as the universality. In addition, a plausible mechanism of UIMA is proposed, involving short DNA bending, mismatch extension, and template slippage. UIMA is a good explanation for why nonspecific amplification easily happens in existing INAAs. As the simplest INAA till now, UIMA provides a new insight for deeply understanding INAA and opens a new avenue for thoroughly addressing nonspecific amplification.

Effect of process duration on the microstructures of fast multiple rotation rolling-induced nanocrystalline layer and its wear properties

A nano-structured surface layer was prepared on the top surface of commercially pure titanium by fast multiple rotation rolling(FMRR) technique for the first time. X-ray diffraction (XRD), field emission scanning electron microscopy(FE-SEM), transmission electron microscopy(TEM), optical microscopy(OM), as well as Vickers test and wear test were used to characterize the microstructural evolution and mechanical properties of the nano-structured layer. The results indicated that when the treatment lasts for 60min, the average grain size reduces to as small as 50nm, and high-density mechanical twining was observed in deformed grains. Moreover, the surface modification resulted in an approximately two-fold increase in microhardness of the nano-structured surface layer and remarkable enhancement in wear resistance. The hardness reached up to 280HV0.05, and friction coefficient declined from 1.1 to 0.6 at sliding velocity of ∼0.1m/s. The obtained results revealed that mechanical twining took precedence in the plastic deformation, and twining and dislocation interaction were induced in the refined nano-structured layer on the surface by FMRR.

Electrospun silk-polyaniline conduits for functional nerve regeneration in rat sciatic nerve injury model

The present study describes the fabrication of polyaniline-silk fibroin (PASF) nanocomposite-based nerve conduits and their subsequent implantation in a rat sciatic nerve injury model for peripheral nerve regeneration. This is the first in vivo study of polyaniline-based nerve conduits describing the safety and efficacy of the conduits in treating peripheral nerve injuries. The nanocomposite was synthesized by electrospinning a mixture of silk fibroin protein and polyaniline wherein the silk nanofibers were observed to be uniformly coated with polyaniline nanoparticles. Tubular shaped nerve conduits were subsequently formed by multiple rolling of the electrospun sheet over a stainless steel mandrel. The conduits were characterized in vitro for their physico-chemical properties as well as their compatibility with rat Schwann cells. Upon implantation in a 10 mm sciatic nerve injury model, the conduits were evaluated for their neuro-regenerative potential through extensive electrophysiological studies and monitoring of gait pattern over a course of 12 months. Gross examination, histological and ultra-structure analyses of the conduits and the regenerated nerve were also performed to evaluate morphological regeneration of transected nerve. PASF nanocomposite conduits seeded with Schwann cell (cell seeded PASF) exhibited excellent nerve conduction velocity (NCV) (50 m s−1), compound muscle action potential (CMAP) (12.8 mV), motor unit potential (MUP) (124 μV), growth of healthy tissue along the nerve gap and thick myelination of axons 12 months after implantation indicating enhanced neuro-regeneration. The excellent functional recovery achieved by animals implanted with cell seeded PASF conduits (86.2% NCV; 80.00% CMAP; 76.07% MUP) are superior to outcomes achieved previously with similar electrically conductive conduits. We believe that the present study would encourage further research in developing electrically active neural implants using synthetic conducting polymers and the in vivo applications of the same.

Automated local line rolling forming and simplified deformation simulation method for complex curvature plate of ships

Abstract. Local line rolling forming is a common forming approach for the complex curvature plate of ships. However, the processing mode based on artificial experience is still applied at present, because it is difficult to integrally determine relational data for the forming shape, processing path, and process parameters used to drive automation equipment. Numerical simulation is currently the major approach for generating such complex relational data. Therefore, a highly precise and effective numerical computation method becomes crucial in the development of the automated local line rolling forming system for producing complex curvature plates used in ships. In this study, a three-dimensional elastoplastic finite element method was first employed to perform numerical computations for local line rolling forming, and the corresponding deformation and strain distribution features were acquired. In addition, according to the characteristics of strain distributions, a simplified deformation simulation method, based on the deformation obtained by applying strain was presented. Compared to the results of the three-dimensional elastoplastic finite element method, this simplified deformation simulation method was verified to provide high computational accuracy, and this could result in a substantial reduction in calculation time. Thus, the application of the simplified deformation simulation method was further explored in the case of multiple rolling loading paths. Moreover, it was also utilized to calculate the local line rolling forming for the typical complex curvature plate of ships. Research findings indicated that the simplified deformation simulation method was an effective tool for rapidly obtaining relationships between the forming shape, processing path, and process parameters.

Mechanical Properties, Microstructure and Phase Composition of Thin Magnetron Sputtered TWIP Steel Foils

Abstract Some high manganese austenitic steels show extraordinarily high ductility due to twinning induced plasticity (TWIP). The TWIP-effect is based on the formation of crystal twins in the austenitic lattice structure as a response to mechanical strain resulting in an extraordinary high ductility. Therefore, TWIP steels are very interesting for forming processes like deep drawing. Within the collaborative research center 747 (SFB 747 “Mikrokaltumformung”) of the German Research Foundation (DFG), micro-components are produced by deep drawing from thin metal foils with thicknesses from 20 μm to 50 μm. The production of such foils by conventional methods as multiple rolling processes of cast sheets is very time consuming since the initial defect free crystal lattice has to be recovered repeatedly by heat treatments after each rolling process to reach a final foil thickness below 50 μm. In the present work, physical vapor deposition (PVD) by DC magnetron sputtering was used as an alternative way to produce thin (≈ 15 μm) TWIP steel foils. An iron based alloy with 25 mass % manganese, 3 mass % silicon and 3 mass % aluminum was deposited onto 100 μm copper foils. After the deposition process the copper substrate foils were removed by selective etching without affecting the resulting TWIP steel films. Microstructure, phase contents and mechanical properties of the resulting PVD-X5MnAlSi25-3-3 TWIP-steel foils were characterized as a function of post annealing conditions. Additionally, the influence of the roughness of the copper substrate foils on the mechanical properties of the resulting PVD-TWIP steel foils was investigated.

The effect of changes in Al-based amorphous phase structure on structure forming upon crystallization

The influence of heat treatment and deformation on structural changes of Al-based amorphous alloys in the amorphous state and at early stages of crystallization has been studied using the methods of X-ray diffraction, differential scanning calorimetry and transmission electron microscopy. It is shown that isothermal annealing and multiple cold rolling bring about formation of an inhomogeneous amorphous phase with the areas of different chemical composition. The formation of an inhomogeneous amorphous phase accelerates the process of nanocrystallization of Al-based alloys. The conditions of treatment of the amorphous alloy in the amorphous state affect the size and fraction of nanocrystals forming in the amorphous phase upon subsequent heating. The size of nanocrystals in the case of preliminary deformation is smaller than that upon preliminary isothermal annealing. We discuss the reasons for the formation of nanostructures containing smaller nanocrystals in the case of thermal and deformation treatments before the onset of crystallization.

Processing of ultrafine-grained titanium with high strength and good ductility by a combination of multiple forging and rolling

The microstructure and the mechanical properties of Grade 2 titanium semi-products processed by a combination of multiple-forging and subsequent plane rolling are studied. It is shown that the application of this technology on Grade 2 titanium doubled the strength without considerable deterioration of ductility at room temperature. The high strength is caused by the ultrafine-grained (UFG) microstructure with high dislocation density. The minimum grain size and the maximum dislocation density achieved by the combined method were very low (~560nm) and high (~18×1014m−2), respectively. Mechanical modelling suggests that the effectiveness of multiple forging in grain refinement is mainly caused by the large, homogeneous imposed strain in non-monotonic strain path, similar to conventional severe plastic deformation (SPD) methods. The total equivalent strain at the end of the rolling step is about 4.4. The good ductility of this material can be attributed to the coarse grains embedded in the UFG matrix which formed due to dynamic recovery and recrystallization at the elevated temperature of rolling. It is proved that the combined method of multiple-forging and plane rolling might be a candidate technology in mass-production of UFG titanium with improved mechanical properties.

Design of a discrete bending joint using multiple unit PREF joints for isotropic 2-DOF motion

Miniature steerable robots are required for various medical applications. Although a typical continuum joint mechanism has a great advantage of miniaturization, it is difficult to have a small bending radius of curvature. With a discrete joint, it is easy to secure definite bending with strength; however, a coarsely structured joint cannot provide a stable distal rolling motion to the end-effector. This paper proposes a method to construct a 2-DOF discrete bending joint using multiple pulleyless rolling joints with an example of a 4-segmental joint. The effects of the stacking sequence on its performance are analyzed. Then, three evaluation criteria are established, and the best stacking sequences are determined. The proposed design method is valid for various numbers of unit joints, and it can be easily applied to the structural design of soft robots resembling snakes or elephant trunks.