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Degree of branching (DB) describes the level of structural perfection of a hyperbranched polymer when compared to its defect-free analogue, namely the dendrimer. The strategy most commonly used to achieve high DB values, specifically while using AB2 type self-condensations, is to design an AB2 monomer wherein the reaction of the first B-group leads to an enhancement of the reactivity of the second one. In the present study, we show that an AB2 monomer carrying a dimethylacetal unit and a thiol group undergoes a rapid self-condensation in the melt under acid-catalysis to yield a hyperbranched polydithioacetal with no linear defects. NMR studies using model systems reveal that the intermediate monothioacetal is relatively unstable under the polymerization conditions and transforms rapidly to the dithioacetal; because this second step occurs irreversibly during polymer formation, it leads to a defect-free hyperbranched polydithioacetal. TGA studies of the polymerization process provided some valuable insight...

Fractionated crystallization (FC), a chain-sorting mechanism by length, is identified in well-defined, low molecular weight, and defect-free regioregular poly(3-hexylthiophene) by X-ray scattering and calorimetry of bulk samples. While wide-angle X-ray scattering (WAXS) qualitatively suggests that the degree of crystallinity is similar in all investigated samples, the melting enthalpies are largely different. We ascribe this to intricacies in the integration of the melting and crystallization peaks in calorimetric experiments, which is caused by FC occurring over a large temperature range. The extent of FC decreases with increasing molecular weight and increases with increasing polydispersity. The temperature-dependent investigation of the long period LP and the (100)-WAXS reflection of a sample in which FC is absent allows to disentangle effects from main-chain and side-chain crystallization.

BACKGROUND: In an effort to improve stroke quality of care and patient outcomes, quality of care metrics are monitored to assess utilization of evidence-based stroke care processes as part of the Paul Coverdell National Acute Stroke Program (PCNASP). We aimed to assess temporal trends in defect-free care (DFC) received by stroke patients in the PCNASP between 2008 and 2018. METHODS: Quality of care data for 10 performance measures were available for 849,793 patients aged ≥18 years who were admitted to a participating hospital with a clinical diagnosis of stroke between 2008 and 2018. A patient who receives care according to all performance measures for which they are eligible, receives “defect-free care” (DFC) (eg, appropriate medications, assessments, and education). Generalized estimating equations were used to examine the factors associated with receipt of DFC. RESULTS: DFC among ischemic stroke patients increased from 38.0% in 2008 to 80.8% in 2018 (P < .0001), with the largest improvement seen in receipt of stroke education (relative percent change, RPC = 64%). Similarly, DFC for hemorrhagic stroke and transient ischemic attack patients increased from 46.7% to 82.6% (RPC = 76.9%) and 39.9% to 85.0% (RPC = 113.0%) (P < .001), respectively. Among ischemic stroke patients, the adjusted odds for receiving DFC were lower for women, patients aged 18 to 54 years, Medicaid or Medicare participants, and patients with atrial fibrillation (P < .05). CONCLUSIONS: From 2008 to 2018, receipt of DFC by ischemic stroke patients significantly increased in the PCNASP; however certain subgroups were less likely to receive this level of care. Targeted quality improvement initiatives could result in even further improvements among all stroke patients and help reduce disparities in care

Implementation science is the study of the translation of evidence-based practices to real-world clinical environments. Implementation is measured with specific outcomes including acceptability, adoption, appropriateness, feasibility, fidelity, penetration, sustainability, and implementation cost. There are defined frameworks and models that outline implementation strategies and assist researchers in identifying barriers and facilitators to achieve implementation and conduct implementation research using methods such as qualitative analysis, parallel group, pre-/postintervention, interrupted time series, and cluster or stepped-wedge randomized trials. Deimplementation is the study of how to remove ineffective or unnecessary practices from the clinical setting and is an equally important component of implementation science.

Understanding the material flow in friction stir welding (FSW) is one of the challenging aspects for producing defect free and quality welds. The material flow is majorly governed by the tool shoulder/pin geometries and process conditions. In the present study, concentric circles shoulder shape with various polygonal pin designs are selected, and their influence on material flow and mechanical properties in Al 6082 friction stir welds is addressed. Material flow is studied by inserting the markers before welding and subsequent analysis of deformed marker material by radiography and macrostructure after welding. The outcome shows the welds with square pin design facilitated a constant stable force, and hexagonal pin design facilitated a decreasing behavior of force with reference to welding length/time. The heat input is increasing from triangular pin to hexagonal pin and is maximum for welds with hexagonal pins (973 kJ/mm). Further, welds with hexagonal pins (TCC)HEX tool facilitated higher mechanical properties of strength (187 MPa) and average hardness (79 HV) at the stir zone.

Molybdenum disulfide (MoS2) is a promising alternative for the anode of Li-ion batteries because of its high theoretical capacity and layered structure for rapid ion transport. However, the issues ...

A rapid growth in the manufacturing industries especially casting industries required rapid quality measuring techniques to maintain the quality standards as well to increase the production rate. Non destructive evaluation (NDE) technique is a one of the major technique used in the manufacturing industries for maintaining it. By using NDE technique, it was easy to find and analyse the data if there were any internal, external and subsurface defects in the cast products. In the present study, four different shapes of casting (Cube, Flat Plate, Cylinder and Circular Plate) of same volume were taken to examine it through non destructive evaluation techniques namely – Visual Inspection, Liquid Penetrant Testing, and Radiography through three different moulding sands (Silica sand, Blast furnace slag and Ferro chrome slag) to analyse the best suitable moulding sand for different shapes. Also, different shapes of casted products reacts differently with different moulding sands in solidification changes which results in the surface quality which was defect free surfaces. Here, the main focus was on effect of four different shape of the components on the three different moulding sands to produce defect free surfaces. AA 2024 material was used for the present study and the casting technique used was CO2 Process. Results revealed that, in visual Inspection there was no visible defect observed in machined parts. Liquid penetration testing reveals that after machining some pores were observed in few places which were not effective defect to show any impact on the surface quality or the properties of the casts. No major surface defects were observed. Radiography Testing resulting in no visible internal defect was observed on all the components.

Recent developments in precision manufacturing along with miniaturization of parts have put strict requirements on edge and surface finishing processes. It not only requires clean and defect free surfaces but also maintain previously generated precision dimensions on advance engineering material. The burr is undesired but inevitable, real productivity killer and amid the most worrying obstructions to mechanization of machining processes, hence affecting quality. Deburring and edge quality is of concern for the performance, cost, safety and appearance of the parts. Over the years electrochemical deburring (ECD) has emerged as a tool for removal of the burrs and retain the requisite edge tolerances exclusive of damaging formerly generated precision dimensions. Conventional ECD process working on the electrochemical principle has been now coupled with faradayic technology to enhance process capability. It is well known that ECD process works for conductive work materials and in specific applications. This review encompasses fundamental principle, parametric analysis and capabilities of the ECD processes that have been evolved through cross innovations. It also critically analyzes mathematical approaches for the modeling of the process in conjunction with their key formulations. Further it discusses the areas which need to be explored.

Today's demand for additive manufacturing has increased. In particular, in materials processing. The main reason for this is that in material processing, the defect free component is made by additive manufacturing. Aluminium based component is being used very much today, but when aluminium based alloy is processed with any other method, several types of defects occur. While fewer defects have been observed in aluminium based components made from additive manufacturing. Further, t is quite a task to fabricate aluminium structures using selective layer melting (SLM) as many parts suffer defects. This paper highlights the recent advancements that have been made to improve the same in recent years and some key topics that require further studying, which is necessary for industrial demands.

The heat dissipation across the moulding sand decides the rate of solidification of castings. For defect free castings, the cooling rate has to be at a preset level. The coarse, medium and fine sand moulds, the properties of the moulding sand like permeability, green compression strength, flowability, compactibility, and mould hardness influence the heat dissipation rate across the mould. An experimental investigation is carried out to understand the influence of these parameters over heat dissipation rate. The grain coarse and fine are found to a major influencing parameter. Analysis of results gives solidification time of Aluminum casting in coarse, medium & fine sand moulding and the inter relationship between physical properties and solidification rate.

Three dimensional printing is a kind of production of things stratum by stratum deposition of material. It helps to cross many limitations to manufacture the product with desired features which are difficult to machine in subtractive manufacturing methods. At earlier stage of progress of three dimensional printing, objective of coming out with basic creation of some trial products, reduces the manufacturing time in reckoning. Current trend is with powder-based AM, where a part is manufactured with DMLS (Direct Metal Laser Sintering process) which helps to produce an end-use part. Every manufacturing process will be having some defects during the unorganized parameters. In this regard, this paper discusses about the complete procedure of DMLS and defects and the causing parameters to facilitate the trouble free and defect free manufacturing of parts. This papers also addresses the research scopes.

Purpose The quality of lost foam casted engineering components is directly influenced by the characteristics of the respective ceramic shell mold (CSM) and hence casting pattern. In this present work, rapid prototyping (RP) was used to fabricate the lattice structured patterns (LSPs) to reduce the defects and cracks in CSM during the heating stage. Design/methodology/approach The quality of the LSPs was accessed by measuring the dimensional accuracy. Further, the thermal stress in the CSM during the heating of porosity varied LSPs was analyzed using ANSYS software package 16.0. The Ni-alloy casting was fabricated by using the designed LSP and compared with its respective CAD model to access its quality. Findings The obtained results revealed that the Wigner–Seitz LSPs retained high accuracy and minimized the stress for defect-free CSM. Also, the thermal stress generated in the CSM depends upon the porosity coefficient of the LSP. Hence the interplay with porosity coefficient of LSPs leads to the formation of defect free CSM and hence high quality casting. Originality/value RP was used to develop LSPs and investigated the dependency of unit cell parameters on the accuracy of the final casting.

Radiation defects-induced plastic flow localization is the origin of loss of ductility in irradiated metals. Defect-free channels (DFCs) are a typical form of strain localization that lead to crack initiation and premature failure. A comprehensive understanding of the DFC dynamics is key to managing radiation boosted property degradation. Despite great research efforts, a clear mechanism of DFC remains unknown. Here, our in-situ tests on irradiated Ni pillars provide a real-time observation of the dynamics of DFCs, including DFC initiation, extension and thickening. The merging and spreading of dislocation loops serve as an alternative mechanism of dislocation sources that emit massive dislocations and initiate nano-thick DFCs inside the grain. Nano-thick DFCs were formed through chopping up or sweeping away of loops by mobile dislocations. Annihilation of opposite loops and interactions between loops and vacancies accelerate DFC extension. Activation of multiple dislocation sources and dislocation cross-slips are the mechanisms for DFC thickening.

Herein, we have successfully demonstrated the microstructural evidence of the inhomogeneous interfaces in multilayered capacitors and explained the role of interface activation in the dielectric pe...

Peak temperature arising during the joining of metals by friction stir welding (FSW) needs to be investigated along with other process parameters of FSW to understand their inevitable impact on joint quality. This investigational and experimental analysis aims to determine the impact of pin geometry and its rotational speed by formulating thermic mechanical process-based models to anticipate peak temperature and to compare it with actual values. Three distinctive pin geometries rotated at three speeds were used while other parameters were unchanged. The fitness and suitability of the model were verified by comparing the anticipated values with the experimental values. Macrographic and micrographic observations revealed that flawless joints with improved mechanical properties were fabricated at a peak temperature of 616 K (80 % melting temperature) when a taper cylindrical pin with a rotational speed of 818 rpm was employed. In addition, SEM analysis of the fractured specimen confirmed that failure of the defect free weldment occurred in brittle mode, indicating that preferred fusion of grains and their constituents occurred during the joining process.

Surface of cold-rolled steel intended for automotive body panel applications is expected to be defect free. The presence of surface defects hampers the aesthetics and average surface roughness and thereby deteriorates the paintability of the steel sheet. This study aims to investigate the source of white patch defect in cold-rolled and skin-passed interstitial free steel sheets. Macroscopic observations of as-received white patch sample revealed the presence of blackish deposit having cracks inside the deposits, suggesting that these deposits were heated up possibly during annealing process. Further during macroscopic observation, it was revealed that the black deposits were of near round shape. If deposit is present before rolling, then it is expected that it will elongate during rolling and will not retain round shape. Round shape of the deposits under investigation suggested that it is not before rolling. Electrolytic cleaning line (ECL) is the only in-between process. Surface characterization techniques such as SEM–EDS, Raman spectroscopy, Fourier transform infrared spectroscopy were used to analyze the defect and good region of the steel sheet. Overall analysis indicated grease contamination on cold-rolled steel sheet at the entry of ECL caused generation of white patch defect. Regular cleaning and preventive maintenance of plant machinery were recommended to avoid such leakages to arrest the defect generation in the future.

The localization of photogenerated electrons in photovoltaic and photocatalytic materials is crucial for reducing the electron–hole recombination rate. Here, the photogenerated electron localization is systematically investigated on the CH3NH3PbI3 (MAPbI3) perovskite using first-principles calculations. It is found that under vacuum conditions, the photogenerated electron is delocalized in the MAPbI3 bulk as well as on the stochiometric MAPbI3(001) surface with the CH3NH3I (MAI) termination, while it is trapped on the defect-free PbI2-terminated surface. Our ab initio molecular dynamics simulations reveal that the introduction of solutions will prompt the formation of localized electronic states. The photogenerated electron is discovered to be localized on both the MAI- and PbI2-terminated surfaces in the presence of solutions with different concentrations of HI, from pure water to the saturated solution. We demonstrate that the Pb–I bond weakening or breaking resulting in an unsaturated coordination of a Pb site is the prerequisite to trap the photogenerated electron.

Analysis of hot-filament CVD (HF-CVD) growth of high quality 3C-SiC on micron-sized 3C-SiC mesas is presented. Two types of growth were observed: 1) a relatively slow growth at about 1μm/hour, and 2) an almost three times faster growth, correlated with the presence of domain boundaries in, or adjacent to, the mesas. Both reveal well-defined crystallographic facets and sharp corners between them. The slower growth has been identified to be surface-nucleation-limited, seemingly defect-free, while the faster growth has been identified as being caused by defect-induced step-flow growth. A growth model is presented, yielding a growth rate of 1.18 μm/h for the defect free {111} and (100) plane and 2.8 μm/h for {110} planes.

The auto-leveling system of a modern draw frame is widely used for conventional fibers to develop homogeneous, uniform, and defect free drawn slivers. This auto-leveling system also improves the quality of tapes and hybrid yarn structures by eliminating mass irregularities in hybrid sliver. However, the existing auto-leveling system exerts very high loads on feedstock, thus diminishing the quality of waste carbon in the delivered sliver. The aim of the present study was to process hybrid sliver based on waste carbon and polyamide fibers on a modern draw frame and modify the auto-leveling system to enable the damage-free processing of carbon fiber. For this purpose, hybrid card slivers were processed on an industrial draw frame with auto-leveling system. The different auto-leveling parameters, e.g., scan roller width and scan roller load, were modified and optimized for the uniform and damage-free processing of hybrid sliver. Results revealed that the scan roller load has a significant influence on the quality of waste carbon fiber in hybrid sliver. A uniform hybrid sliver ensures the reproducibility of unidirectional tapes and hybrid yarn at industrial scale, while simultaneously maintaining the quality of recycled carbon fiber-reinforced thermoplastics.

The effect of CNTs on the mechanical and damping properties of macro-defect-free (MDF) cements was studied, and polyvinyl alcohol (PVA) fibers were also studied as a contrast. It was found that the compressive strength of MDF cements was not significantly affected by the two types of fibers. The CNTs enhanced the flexural strength of MDF, while PVA fibers made negative contribution. The strengthening mechanism of flexural strength of MDF cements by CNTs can be summarized as fiber bridging, crack deflection and fiber slippage. For the damping properties, the proper contents of CNTs and PVA fibers improved the loss factor significantly. The interface transition zone (ITZ) between the PVA fibers and matrix was large, which was favorable for fiber slippage. The damping property of MDF cements with CNTs was mainly due to the slippage between the inner tubes of the CNTs rather than the slippage between the CNTs and matrix.

Chitosan (CS) nanofibers were electrospun from aqueous chitosan solution using concentrated acetic acid solution as a solvent. Polyethylene oxide (PEO) with varying weight content from 10- 60 wt% was mixed with chitosan solution that acted as a plasticizer to improve spinability of the prepared chitosan solution. With the increase in PEO content from 10-50 wt% the viscosity of the resultant CS/PEO solution was decreased from 0.938 Pa-s to 0.272 Pa-s, whereas higher the concentration of acetic acid lower was the surface tension of resultant chitosan solution. It was found beadless nanofibrous chitosan mat was obtained not less than 85% acetic acid concentration, 50 wt% PEO and at 0.2 wt% NaCl and 5 wt% total polymer concentration. From field emission scanning electron microscopy (FESEM) investigation, it was observed that chitosan fibers with an average diameter of 149 nm were produced at an applied voltage of 22.5 KV, while that varied between 17.5- 25 KV. On the other hand, a minimum of 110 nm of average diameter chitosan nanofiber was obtained at a needle tip to rotor collector distance of 15 cm by the method of electrospining. In terms of solution flow rate, 0.4 mL/h was found to be optimum in obtaining defect-free electrospun fiber with lower average diameter. As a whole, smooth and uniform chitosan nanofibers were obtained from 50/50 CS/PEO solution prepared by using 90% acetic acid and electrospun at 20 kV applied voltage, 15 cm needle tip-to- rotor collector distance with 0.2 mm inner diameter needle and 0.4 mL/h feeding rate. After crosslinking with 1 wt% glutaraldehyde (GTA), the ultimate tensile strength and Young's modulus of chitosan scaffold increased upto 9.47 MPa and 147.75 MPa respectively. From MTT assay and alkaline phosphatase expression analysis upto 11 days of cell culture period it was evident that thus prepared electrospun CS scaffolds supported MG 63 cell proliferation and its differentiation into mature osteoblast.

In this paper, Experimental investigation is carried out on IS2062-EN31 dissimilar MIG weldments and influence of different heat inputs on the properties different zones of welded structures. Low heat input (5.7238 kJ/mm), high heat input (6.714 kJ/mm) conditions are selected and with help of these heats input conditions made of 8 mm thickness defect free weldments are prepared. It is found that the joint fabricated at a low heat input condition showing excellent metallurgical and mechanical properties. Both Mechanical and metallurgical properties of the joint improved with low heat input condition, fine grain size was measured with at welded zone and it decreased. Tensile and hardness is improved due to grain size was observed to be Eight with high and Nine low heat input condition.

Magnetically impelled arc butt (MIAB) welding is a pressure welding process used for joining of pipes and tubes with an external magnetic field affecting arc rotation along the tube circumference. In this work, MIAB welding of SA210GrA tubes were carried out to study the microstructure of weldedments. The effect of arc current on the weld interface is also detailed and is found to be defect free at higher values of arc currents. The results reveal that MIAB welded specimens shows superior structural property correlation for high pressure applications with an added benefit of improved productivity at lower cost. The study will enable the use of MIAB welding for high pressure applications in power and defence sectors.

AA7075 alloy in T6 condition is friction stir processed using a H13 tool with square profiled pin. Tool rotational speed and traverse speed are the two major input factors chosen for the study. A constant plunge depth is maintained for every pass to generate adequate input. Experiments are conducted at different levels of tool rotational speed and traverse speed and the behaviour of the tool during each pass and the corresponding processed surface is observed. The input parameter that caused tool failure was noted and a boundary is drawn to represent the processing zone that produces a defect free stir zone.

The automobile and aeronautical sectors have simulated the emergence of processes that yield defect free components. Squeeze casting is one such novel process that is mostly adopted to produce light weight alloys of Aluminium and Magnesium. The influence of squeeze cast process parameters on wear behavior of AA6061 was investigated in this study by employing Taguchi method. The process parameters considered in this study were pressure, die temperature and pressure duration respectively. L9(34) orthogonal array of Taguchi method was chosen to conduct the experiments and the squeeze cast components were produced. The pins were made from these components and they were subjected to wear test. The wear rate was obtained from the weight loss of the pin. The analysis showed that the parameters such as pressure and die temperature caused appreciable improvement towards the wear resistance exhibited by AA6061 components.

Quantum computers have been proposed that exploit entangled quantum states between atoms that are isolated from environmental perturbations in a “semiconductor vacuum” which can be formed by cryogenically cooling an isotopically pure, defect free crystalline layer consisting of Si, or Ge. In a preliminary investigation of an implant and deposition layer exchange technique to produce such “vacuums”, a layer of aluminium was implanted with 28Si using a conventional implanter. After annealing and cross sectioning, layer exchange was observed to have produced multiple isolated crystals in a cross sectional TEM image. Further deposited Al layers were implanted with Ge using a SIMPLE (Single Ion Multispecies Positioning at Low Energy) implanter over a range of fluences. After anneals at 250 °C and Al removal, crystals of Ge (which also contained Si) were seen at areal densities that increased with implant fluence.

We took advantage of the microflow hydrodynamics in the evaporation of sessile droplets to increase the height uniformity of thin lipid films for the subsequent electroformation of defect-free giant unilamellar vesicles (GUV). By serially casting progressively larger liposome suspension droplets on the same spot of an indium-tin-oxide (ITO) electrode, we managed to leverage the coffee ring effect (CRE) in the evaporation of each droplet to generate a smeared multilayer film of uniform thickness. This multidroplet technique of lipid film formation outperformed the traditional single-droplet deposition, improving the final quality of electroformed GUV samples. The proposed film formation technique constitutes a solvent-free method that results in a dramatic reduction (∼20×) in the appearance of undesirable structures like nonspherical (NSV), multilamellar (MLV), and multivesicular (MVV) vesicles.

The disability of lower limbs is one of the major problems facing human lives. In order to restore the missing functionality and aesthetic feature of the amputee's locomotion, finding the optimal design of the human lower limb knee prosthesis is crucial. This paper focuses the design optimization of a four bar knee mechanism capable to reproduce the complex flexion/extension knee joint motion in the sagittal plane with variable instantaneous center of rotation positions. Thus an optimization approach with appropriate constraints is formulated in order to consider the degree of compatibility between the instantaneous center of rotation trajectories of the human reference knee joint and the four bar knee mechanism. To solve this high nonlinear optimization problem, an algorithm based on multi-objective modified imperialist competitive method is proposed where all the constraints are managed with the penalty method. The results obtained by the multi-objective modified imperialist competitive method showed the capability to reach a small tracking error. The obtained results prove the effectiveness of the proposed optimization approach for the optimal synthesis of the four bar knee mechanism, compared with other literature techniques.

In this paper, we present a machine learning algorithm to synthesize defect-free single-degree-of-freedom spatial mechanisms for the Alt–Burmester problem. The Alt–Burmester problem is a generalization of a pure motion synthesis problem to include via path-points with missing orientations. While much work has been done towards the synthesis of planar and, to some extent, spherical mechanisms, the generation of mechanisms that are free of circuit, branch, and order defects has proven to be a difficult task. This is even more challenging for spatial mechanisms, which can consist of a large number of circuits and branches. Moreover, the Alt–Burmester problem makes solving such problems using an analytical approach further demanding. In this paper, we present a novel machine learning algorithm for solving the Alt–Burmester problem for spatial 5-SS platform mechanism using a variational autoencoder (VAE) architecture. The VAE helps capture the relationship between path and orientation properties of the motion of the 5-SS mechanisms, which enables reformulating the Alt–Burmester problem into a pure motion synthesis problem. The end goal is to produce defect-free spatial mechanism design solutions. While our focus in this paper is on the 5-SS mechanisms, this approach can be scaled to any single-degree-of-freedom spatial mechanisms.

Cantilevered beams with piezoceramic layers are typically used to generate electrical energy; hence, a base excitation on a harvester is required. This work investigates the use of a link-type mechanism called the Peaucellier mechanism to actuate piezoelectric energy harvesters. The Peaucellier mechanism is known to trace an exact straight line, providing harmonic motion, which is exploited here for exciting a bimorph piezoelectric cantilever beam. To generate the required base excitation, a function generation synthesis methodology for designing a defect-free Peaucellier mechanism driven by a dyad (PMD) is proposed, in addition to an example being provided to confirm the efficacy of the method. The harmonic motion involves two design variables (frequency and amplitude) which are key parameters and can be tuned to generate the required electrical power. It was determined that PMD could excite the energy harvester, generating an electrical power of approximately 4.52 μ W at low frequency. The synthesis generated a mean absolute error of 0.061 m/s2 confirming an excellent match between the points of the input-output and desired acceleration. The results confirm that the Peaucellier mechanism is suitable for the actuation of energy harvesters where parasitic power harvesting is required in different practical applications, including robotics and stationary machines.

In industrial quality assessment, it is challenging to conduct automated and accurate defect segmentation under the condition that abundant defect-free images but very limited anomalous images are available. This paper tackles the challenging few-shot defect segmentation task under such condition. We propose two regularization techniques via incorporating abundant defect-free images into the training of an encoder-decoder segmentation network. We first propose a Normal Background Regularization (NBR) loss which is jointly minimized with the segmentation loss, enhancing the encoder network to produce discriminative representations for normal regions. Secondly, we crop/paste defective regions to the randomly selected normal images for data augmentation and propose a weighted binary cross-entropy loss to enhance the training by emphasizing more realistic crop-and-pasted augmented images based on feature-level similarity comparison. Extensive experiments on MVTec AD and MTSD datasets demonstrate the superiority of the proposed method over the competing methods under few-shot settings.

Potassium-ion batteries (KIBs) are promising electrochemical energy storage systems because of their low cost and high energy density. However, practical exploitation of KIBs is hampered by the lack of high-performance cathode materials. Here we report a potassium manganese hexacyanoferrate (K2Mn[Fe(CN)6]) material, with a negligible content of defects and water, for efficient high-voltage K-ion storage. When tested in combination with a K metal anode, the K2Mn[Fe(CN)6]-based electrode enables a cell specific energy of 609.7 Wh kg−1 and 80% capacity retention after 7800 cycles. Moreover, a K-ion full-cell consisting of graphite and K2Mn[Fe(CN)6] as anode and cathode active materials, respectively, demonstrates a specific energy of 331.5 Wh kg−1, remarkable rate capability, and negligible capacity decay for 300 cycles. The remarkable electrochemical energy storage performances of the K2Mn[Fe(CN)6] material are attributed to its stable frameworks that benefit from the defect-free structure., Potassium-ion battery is a promising candidate for post-Li-ion energy storage but the lack of cathode materials hinders practical exploitation. Here the authors investigate defect-free potassium manganese hexacyanoferrate as cathode active material for high energy and long lifespan K-based cells.

The authors propose a rearranging-atom algorithm with near-fewest sorting-atom moves for large-scale atom assemblers and apply to the preparation of defect-free atom arrays in compact configurations experimentally.

In a very short time, direct (hetero)arylation polymerization (DHAP) has established itself as a valuable and atom-economical alternative to traditional cross-coupling methods such as the Migita–Stille and Suzuki-Miyaura polymerizations for the synthesis of low cost and efficient conjugated polymers for organic electronics. Because of sustained research efforts combining in-depth theoretical calculations, the development of new ligands and the careful fine-tuning of polymerization conditions, selectivity and reactivity issues should be soon a thing of the past. This focus review highlights the recent advances that lead to defect-free polymeric semiconductors and conductors and the current limitations and challenges of DHAP as it moves toward simultaneously becoming an industrially feasible, environmentally friendly, and synthetically powerful polymerization technique. The implementation of Direct Heteroarylation Polymerization (DHAP) in the synthesis of well-defined and defect-free materials for organic electronics is still in its early stages but giant leaps have been made over the past few years to improve and stir the selectivity of the reaction to avoid unwanted side-reaction such as β-branching or homocoupling. DHAP has proven to be an efficient, cost-effective, green and scalable polymerization method now competing or even surpassing well-established Suzuki-Miyaura or Migita–Stille cross-coupling polymerization methods. This focus review puts emphasis on the synthetic strategies that made DHAP successful.

Introducing defects into graphene has been widely utilized to realize the negative magnetoresistance (MR) effect in graphene. However, the reported graphene negative MR exhibits only ∼ 10% under 10 T at room temperature to date, which extremely limits the resolution of future spintronics devices. Moreover, intentional defect introduction can also cause unintentional degradation in graphene’s intrinsic properties. In this paper, we report a magnetic logic inverter based on a crossed structure of defect-free graphene, resulting in a substantial gain of 4.81 mV/T while exhibiting room temperature operation. This crossed structure of graphene shows large unsaturated room temperature negative MR with an enhancement of up to 1,000% at 9 T. A transition behavior between negative and positive MR is observed in this crossed structure and the transition temperature can be tuned by a ratio of the conductivity between in-plane and out-of-plane transport. Our results open an intriguing path for future two-dimensional spintronics device applications.

Periodic deviation of the diameter of wheel across its circumference is referred to as the out-of-round (OOR) defect that can cause significant damages to wheel – rail interface, affect the service life of various components of the vehicle/track system and the safety of trains. Under braking, OOR defect may exacerbate these damages; to uncover such exacerbation, a multi-body dynamic simulation model in a fixed coordinate system for wagons containing new/ defect free or OOR wheels subject to braking torques has been formulated and validated using a dataset in the literature. Using the validated model, the effects of the repetition order (single or multiple deviations of diameter) of OOR defect and the severity of application of braking torques to wheel wear has been examined. It has been found that under constant speed, the normal contact force increased with the repetition order. The OOR defect dominated the normal contact force with a dynamic impact force factor of 1.48, whilst the new/ defect free wheels exhibited negligible impact force. It is shown that the effect of OOR defect is significant for wear of wheels under normal braking whist under wheel skid, braking torque dominates wear. Wheel unloading ratio is shown to be a better indicator for the determination of risk to derailment, than the commonly used Nadal's derailment quotient where the wheel contains OOR defect.

The requirement for utilization of safe lubricants is rising in all parts of the industry due to human and environmental concerns. Therefore, complete omission or replacement of the mineral-based cutting fluids by safer ones is deemed to be very important in today’s machining operations. In the present study, the effect of pre-cooling in cryogenic machining using liquid nitrogen was compared with dry machining. Tool temperature, workpiece surface quality and tool wear were studied as the output response parameters. The results showed that the tool temperature had no sensitivity to the cutting parameters when liquid nitrogen was employed. However, in dry machining as the cutting parameters (i.e., cutting speed and feed rate) increased, the cutting temperature rose. Pre-cooling by liquid nitrogen led to reduction of the tool temperature by 73–86% compared with the dry method. Also, surface quality in terms of defective zones such as adhered materials, removed regions, and scratch marks was evaluated. It was observed that many defects were formed on the workpiece surface in dry machining, whereas it was completely defect free in cryogenic machining. Concerning the tool wear, the SEM images of tool rake face showed that the tool wear under the mechanisms of adhesion and breakage was observed in a vast area of the tool surface in dry machining, enhancing the creation of defects on the workpiece surface.