Assembly Method Research Articles

(Invited) Biofabricated Carbon Nanotube Electronics: Toward Energy-Efficient Switches in Multi-Dimensional Integration

High-performance Si devices are approaching their physical boundaries during the continuous miniaturization following Moore's Law. New semiconductor materials are in urgent necessity, among which, carbon nanotubes（CNTs）are suggested by the International Technology Roadmap for Semiconductors（ITRS）as potential candidate to continue Moore's Law due to its quasi-one-dimensional structure and excellent electrical properties.To unleash the advantages of CNTs in the post-Moore era, optimizing materials morphology, interfaces composition, and integrated structure proves to be pivotal, which constitutes the basic idea of our research. Regarding material morphology, we have fabricated evenly spaced parallel CNT materials with a spacing down to 10nm, by employing the DNA-directed high-precision assembly method. At CNT interface, we have realized fast on/off switching high-performance switches by engineering the interfacial compositions. Individual CNT displays 1G0 conductance with subthreshold swing superior to conventional Si transistors. Furthermore, we built the preliminary foundation to integrate CNT transistors into multi-dimensional circuits. Based on the control of material, interface, and integration structure, our work elucidates the potential of constructing energy-efficient computing circuit using carbon nanotube electronics.

Recent Advances in 1D Nanostructure Assembly and Direct Integration Methods for Device Applications.

In recent years, 1D nanostructure-based devices have achieved widespread usage in various fields, such as sensors, energy harvesters, transistors, and electrodes owing to their exceptional and distinct properties. The pioneering work of Dr. R. S. Wagner at Bell Laboratories in 1964 introduced the vapor-liquid-solid (VLS) process, a powerful synthesis method. Since then, numerous synthesis techniques, including sol-gel, hydrothermal, chemical vapor deposition (CVD), physical vapor deposition (PVD), and more, have been developed. These methods have enabled researchers to effectively control the shape (length and diameter) and material properties of nanowires. However, itwasonly about two decades ago that nanowires started to be widely utilized as key components in functional devices, primarily due to the lack of proper integration methods. Although dozens of integration techniques have been developed, none have emerged as a predominant choice, with each method presenting its own set of advantages and limitations. Therefore, this work aims to categorize these methods based on their working principles and provide a comprehensive summary of their pros and cons. Additionally, state-of-the-art devices that capitalize on the integration of 1D nanomaterials are introduced.

Reconstructing extrachromosomal DNA structural heterogeneity from long-read sequencing data using Decoil.

Circular extrachromosomal DNA (ecDNA) is a form of oncogene amplification found across cancer types and associated with poor outcome in patients. ecDNA can be structurally complex and can contain rearranged DNA sequences derived from multiple chromosome locations. As the structure of ecDNA can impact oncogene regulation and may indicate mechanisms of its formation, disentangling it at high resolution from sequencing data is essential. Even though methods have been developed to identify and reconstruct ecDNA in cancer genome sequencing, it remains challenging to resolve complex ecDNA structures, in particular amplicons with shared genomic footprints. We here introduce Decoil, a computational method that combines a breakpoint-graph approach with LASSO regression to reconstruct complex ecDNA and deconvolve co-occurring ecDNA elements with overlapping genomic footprints from long-read nanopore sequencing. Decoil outperforms de novo assembly and alignment-based methods in simulated long-read sequencing data for both simple and complex ecDNAs. Applying Decoil on whole-genome sequencing data uncovered different ecDNA topologies and explored ecDNA structure heterogeneity in neuroblastoma tumors and cell lines, indicating that this method may improve ecDNA structural analyses in cancer.

Nanoengineering Multilength-Scale Porous Hierarchy in Mesoporous Metal-Organic Framework Single Crystals.

Developing a reliable method for constructing mesoporous metal-organic frameworks (MOFs) with single-crystalline forms remains a challenging task despite numerous efforts. This study presents a solvent-mediated assembly method for fabricating zeolitic imidazolate framework (ZIF) single-crystal nanoparticles with a well-defined micro-mesoporous structure using polystyrene-block-poly(ethylene oxide) diblock copolymer micelles as a soft-template. The precise control of particle sizes, ranging from 85 to 1200 nm, is achieved by regulating nucleation and crystal growth rates while maintaining consistent pore diameters in mesoporous nanoparticles and a rhombohedral dodecahedron morphology. Furthermore, this study presents a robust platform for nanoarchitecturing to prepare hierarchically porous materials (e.g., core-shell and hollow structures), including microporous ZIF@mesoporous ZIF, hollow mesoporous ZIF, and mesoporous ZIF@mesoporous ZIF. Such a multimodal pore design, ranging from microporous to microporous/mesoporous and further micro-/meso-/macroporous, provides significant evidence for the future possibility of the structural design of MOFs.

Stable Sub‐2‐nm Fe3O4 Particles Confined in P, N Co‐Doped Carbon Derived from the Assembly of DPPF with PCN‐222: A Promising Transfer Hydrogenation Catalyst

AbstractThe nanoconfinement approach for constructing ultra‐small nanoparticles has been effectively utilized in the development of non‐precious metal catalysts. Herein, the catalyst precursor was prepared by host‐guest assembly method, using PCN‐222 as the host and 1,1′‐bis(diphenylphosphino) ferrocene (DPPF) as the guest. After calcination, the sub‐2 nm iron oxide nanoparticles within a phosphorus‐nitrogen co‐doped carbon matrix (Fe3O4@P/N‐CDCM) was obtained. Benefiting from the nanoconfinement effect, the sub‐2 nm Fe3O4 nanoparticles were uniformly dispersed on the P/N‐CDCM matrix. As a representative application, Fe3O4@P/N‐CDCM‐600 showed remarkable catalytic activity in the reduction of various nitroaromatic compounds. Under ambient conditions, the efficient reduction of nitro compounds in aqueous solution led to excellent conversion rates (96–99 %) and selectivity (99 %) within 45 minutes. Additionally, the catalyst maintained high efficiency over 5 cycles without experiencing a noticeable decrease in activity. This work provides an innovative and cost‐effective strategy for fabricating highly dispersed non‐precious metal nanoparticles.

A Flexible MXene-Black Phosphorus/Zinc Oxide Hybrid Structure with Excellent UVA-Specific Photoelectric Sensing Properties for Human Skin Protection.

Ultraviolet A (UVA) radiation causes various irreversible damages to human skin, so the research about UVA-specific sensing device is urgent. 2D black phosphorus (BP) is used in many photosensors due to its advantages of high carrier mobility and tunable bandgap, but its application for UVA-specific photosensor is not reported. Here, a MXene-BP/Zinc oxide (ZnO) hybrid structure with lamellar-spherical interfaces like finger lime fruit is prepared by the layer-by-layer assembly (LLA) method, and p-n junctions are constructed between BP and ZnO with the Ti3C2Tx electrode, showing excellent photoelectric performance. Density functional theory (DFT) calculations demonstrate that the enhanced performance is attributed to the rapid separation of photogenerated carriers in the presence of a built-in electric field at interface. Furthermore, a flexible MXene-BP/ZnO based UVA-specific photosensor is prepared, which shows a specific response to UVA as high as 7 mAW-1 and excellent mechanical stability, maintaining 98.46% response after 100 bending cycles. In particular, the integrated anti-UVA skin protection device shows excellent UVA-specific identification and wireless transmission capability, which can provide timely UVA exposure information and skin protection warning for the visually impaired. This work demonstrates a new approach for further developments of advanced photoelectric sensing technology toward improving people's skin health protection.

Assembly of primary secondary amine over magnetic graphitized carbon black material for selective cleansing of sample matrices

Pigments and organic acids are among the most common impurities in complex sample matrices. Their presence in the samples often interferes with the detection of trace analytes. This study aimed to design and develop magnetic materials (GCB/Fe3O4-PSA) for the efficient purification of organic acids and pigment impurities in sample matrices. We employed the acid modification method to enhance the modification of magnetic Fe3O4 by the primary secondary amine adsorption group (PSA), effectively boosting its adsorption performance. This modification technique not only retains the inherent adsorption characteristics of Fe3O4 but also avoids the irreversible damage to Fe3O4′s own adsorption by traditional grafting methods. Subsequently, Fe3O4-PSA and graphitized carbon black (GCB) were combined through a simple physical assembly method to prepare GCB/Fe3O4-PSA, which was used for the purification of pigments and organic acids in complex matrices. During the purification process, GCB/Fe3O4-PSA can be rapidly magnetically separated. After six reuses, the adsorption performance remains above 80 %, fully demonstrating the rapid purification ability and reusability potential of GCB/Fe3O4-PSA. Compared with unmodified Fe3O4, GCB/Fe3O4-PSA significantly enhanced the purification effect of complex matrices. Its adsorption capacities for chlorophyll and ascorbic acid increased by 276.9 % and 263.9 % respectively. After combining with the GCB/Fe3O4-PSA purification material, cathinones in complex matrix samples (tea, apples, carrots) were determined using UPLC-MS/MS. The recoveries in spiked samples ranged from 96.35 % to 104.17 %, with the RSDs < 3.02 %. Simultaneously, characterization methods such as SEM, FTIR, XRD, VSM, XPS, and BET were used to study the surface structure and chemical composition of GCB/Fe3O4-PSA. The above results highlight the outstanding performance of GCB/Fe3O4-PSA in the efficient purification of organic acids and pigments in complex matrices and also show its considerable application potential in the pretreatment of complex matrix samples.

Study on the establishment method of multi-dimensional chain model and precision assembly for robot precision reducers

Study on the establishment method of multi-dimensional chain model and precision assembly for robot precision reducers

Electrochemical Glycosylation via Halogen-Atom-Transfer for C-Glycoside Assembly.

Glycosyl donor activation emerged as an enabling technology for anomeric functionalization, but aimed primarily at O-glycosylation. In contrast, we herein disclose mechanistically distinct electrochemical glycosyl bromide donor activations via halogen-atom transfer and anomeric C-glycosylation. The anomeric radical addition to alkenes led to C-alkyl glycoside synthesis under precious metal-free reaction conditions from readily available glycosyl bromides. The robustness of our e-XAT strategy was further mirrored by C-aryl and C-acyl glycosides assembly through nickela-electrocatalysis. Our approach provides an orthogonal strategy for glycosyl donor activation with expedient scope, hence representing a general method for direct C-glycosides assembly.

Autonomous Human-Robot Collaborative Assembly Method Driven by the Fusion of Large Language Model and Digital Twin

Autonomous Human-Robot Collaborative Assembly Method Driven by the Fusion of Large Language Model and Digital Twin

Printed circuit board and printed circuit board assembly methods for testing and visual inspection: a review

Testing and visual inspection of printed circuit boards (PCBs) and printed circuit board assemblies (PCBAs) are important procedures in the manufacturing process of electronic modules and devices related to locating and identifying possible defects and failures. Earlier defects detection leads to decreasing expenses, time and used resources to produce high quality electronics. In this paper an exploration and analysis about the current research regarding methods for PCB and PCBA testing, techniques for defects detection and vusial inspection is performed. The impact of machine and deep learning for testing and visual inspection procedures is also investigated. The used methodology comprises bibliometric approach and content analysis of papers, indexed in scientific database Scopus, considering the queries: “PCB and testing” and “PCB and testing”, “printed circuit board assembly and testing” and “PCBA and testing”, “PCB defect detection” and “PCBA defect detection”, “PCB and visual inspection”, and “PCBA and visual inspection”. The findings are presented in the form of a framework, which summarizes the contemporary landscape of methods for PCBs and PCBAs testing and visual inspection.

Integration of Value Engineering for Design for Assembly in Product Design: A Comprehensive of Literature Review

This study explains the benefits obtained from the integration of Design for Assembly (DFA) and Value Engineering (VE) methods in the product design process. DFA is proven to provide benefits such as product simplification, reduced assembly costs, and improved quality by creating product structures that are simpler and easier to install. While VE adds value by taking into account the replacement of expensive or difficult-to-assemble components, speeding up overall assembly time. Although specific research on the integration of these two methods may be limited, studies show that the combination of DFA and VE produces design alternatives that consider various aspects of the product life cycle. The result is reduced costs, faster development times, and a reduced need for rework. The concepts and benefits of integrative DFA and VE approach can be an effective strategy for enhancing assembly efficiency and reducing production costs in product design.

Polyploids of Brassicaceae: Genomic Insights and Assembly Strategies.

The Brassicaceae family is distinguished by its inclusion of high-value crops such as cabbage, broccoli, mustard, and wasabi, all noted for their glucosinolates. In this family, many polyploidy species are distributed and shaped by numerous whole-genome duplications, independent genome doublings, and hybridization events. The evolutionary trajectory of the family is marked by enhanced diversification and lineage splitting after paleo- and meso-polyploidization, with discernible remnants of whole-genome duplications within their genomes. The recent neopolyploidization events notably increased the proportion of polyploid species within the family. Although sequencing efforts for the Brassicaceae genome have been robust, accurately distinguishing sub-genomes remains a significant challenge, frequently complicating the assembly process. Assembly strategies include comparative analyses with ancestral species and examining k-mers, long terminal repeat retrotransposons, and pollen sequencing. This review comprehensively explores the unique genomic characteristics of the Brassicaceae family, with a particular emphasis on polyploidization events and the latest strategies for sequencing and assembly. This review will significantly improve our understanding of polyploidy in the Brassicaceae family and assist in future genome assembly methods.

Physicochemical Methods for the Structuring and Assembly of MOF Crystals.

ConspectusMetal-organic frameworks (MOFs) are promising for various applications through the creation of innovative materials and assemblies. This potential stems from their modular nature, as diverse metal ions and organic linkers can be combined to produce MOFs with unique chemical properties and lattice structures. Following extensive research on the design and postsynthetic chemical modification of MOF lattices at the molecular level, increasing attention is now focused on the next hierarchical level: controlling the morphology of MOF crystals and their subsequent assembly and positioning to create functional composites.Beyond well-established methods to regulate crystal size and shape through nucleation and coordination modulation, physicochemical techniques leveraging wetting effects, interparticle interactions, and magnetic or electric fields offer attractive avenues for the hierarchical structuring and assembly of MOFs. These techniques facilitate crystal alignment and yield unique superstructures. While our research group primarily focuses on directing MOF crystal orientation and positioning using external stimuli such as magnetic and electric fields, we also explore hierarchical MOF synthesis and structuring using liquid interfaces and depletion force-assisted packing.This account highlights our journey and progress in developing methods to regulate the morphology, assembly, orientation, and positioning of MOF crystals, placed in the context of work by other groups. First, we examine commonly utilized structuring methods for MOF crystals that employ liquid-liquid and air-liquid interfaces to spatially confine reactions, allowing us to access unique morphologies such as mushroom-like crystals and Janus particles. We also discuss strategies for concentrating and packing MOF crystals into superstructures, utilizing fluid interfaces for spatial confinement of crystals, depletion forces, entropic effects, and crystal sedimentation.A particularly compelling challenge in expanding the applicability of MOF materials is how to manipulate free-standing MOF crystals. This issue is especially important because MOFs are typically produced as loose powders, and industrial material processing is generally more efficient when the material is fluidized. While extensive research has been conducted regarding MOF growth on substrates with both positional and orientational control, there is a clear need for similar precision with free-standing MOFs dispersed in a fluid matrix. Our group has thus focused on the relatively new, yet powerful approach of using electric and magnetic fields to manipulate MOF crystals, which offers unprecedented control over the orientation and positioning of dispersed MOF crystals, complementing the more well-established methods of MOF growth on substrates. In this Account, we provide foundational background and discussions on the interactions between these external fields and MOF crystals, including critical considerations for effective MOF manipulation using such techniques. We also discuss their unique advantages and applications, and briefly examine potential application areas, such as photonics, smart materials like soft robotics and absorbents, and sensing. This Account highlights the promising potential of well-organized and aligned MOF crystals over randomly oriented ones in various applications, owing to enhanced selectivity and performance. It underscores the importance of specialized assembly methods to advance materials science and engineering, encouraging the reader to explore such approaches.

Harnessing true capacitive activity of nitrogen-doped MXene through hydrogel assembly and theoretical understanding of the role of dopant sites

Heteroatom nitrogen (N) doping in MXene can significantly push its energy storage metric. However, translating the intrinsic improvement of individual sheets into macroscopic electrodes is challenging due to the blockage of dopant sites by restacking. Here, we report the development of restack-controlled N-doped MXene hydrogel through speedy interfacial assembly methods to keep the dopant sites electrochemically accessible. Application of a small voltage between two zinc plates in an aqueous dispersion of N-doped MXene leads to the rapid development of doped hydrogel over the positive zinc plate via electrophoretic drag and linking by interfacial released zinc ions. As-developed hydrogels having continuous porosity and quasi-oriented sheet arrangement preserve ion transporting channels, thus allowing the surface dopant sites to participate in the supercapacitive energy storage actively. N-doped hydrogel displays a high capacitance of 488 F g−1 at 5 mV s−1 much higher as compared to compact film. The N-doped MXene hydrogels display excellent rate performance with retention over 88 % at 1000 mV s−1 and cyclic stability of 87 % over 10000 cycles. The detailed density functional theory (DFT) calculation reveals a major pseudocapacitive contribution from the surface adsorption and functional group substitution type N dopant sites as compared to another dopant site, namely, lattice substitution.

Phytic Acid-Gallium Network on a Polyimide Fiber Woven Fabric as an Artificial Ligament for Boosting Ligament-Bone Healing and Infection Treatment.

The development of an artificial ligament with a multifunction of promoting bone formation, inhibiting bone resorption, and preventing infection to obtain ligament-bone healing for anterior cruciate ligament (ACL) reconstruction still faces enormous challenges. Herein, a novel artificial ligament based on a PI fiber woven fabric (PIF) was fabricated, which was coated with a phytic acid-gallium (PA-Ga) network via a layer-by-layer assembly method (PFPG). Compared with PIF, PFPG with PA-Ga coating significantly suppressed osteoclastic differentiation, while it boosted osteoblastic differentiation in vitro. Moreover, PFPG obviously inhibited fibrous encapsulation and bone absorption while accelerating new bone regeneration for ligament-bone healing in vivo. PFPG remarkably killed bacteria and destroyed biofilm, exhibiting excellent antibacterial properties in vitro as well as anti-infection ability in vivo, which were ascribed to the release of Ga ions from the PA-Ga coating. The cooperative effect of the surface characteristics (e.g., hydrophilicity/surface energy and protein absorption) and sustained release of Ga ions for PFPG significantly enhanced osteogenesis while inhibiting osteoclastogenesis, thereby achieving ligament-bone integration as well as resistance to infection. In summary, PFPG remarkably facilitated osteoblastic differentiation, while it suppressed osteoclastic differentiation, thereby inhibiting osteoclastogenesis for bone absorption while accelerating osteogenesis for ligament-bone healing. As a novel artificial ligament, PFPG represented an appealing option for graft selection in ACL reconstruction and displayed considerable promise for application in clinics.

Assembling Smallest Prussian Blue Analogs Using Chiral Hydrogen Bond-Donating Unit toward Complete Phase Transition.

Exploring methods for assembling functional materials at the molecular level may yield functional expressions derived from the assembly method. This study developed novel switchable molecular assemblies characterized by abrupt, complete phase transitions promoted via hydrogen bonding with a chiral carboxylic acid. These assemblies were prepared by aggregating discrete molecules that are unresponsive to external stimuli. Furthermore, enantiopure hydrogen-bond donor (HBD) molecules provide switchable compounds with cooperative and abrupt phase transitions, whereas the racemic mixture of the HBD provides a hydrogen-bonded one-dimensional compound with a broad and incomplete phase transition when structural disordering is observed. This study presents a novel strategy for observing metal-to-metal electron-transfer-coupled spin transitions via hydrogen-bond formation.

Spray-assisted layer-by-layer deposition of quaternized chitosan/tannic acid for the construction of multifunctional bio-based nonwoven dressings

Gauze wound dressings have received considerable attention due to their cost-effectiveness, excellent mechanical properties, and widespread applications. However, their inability to actively combat microorganisms and effectively scavenge free radicals results in suboptimal wound management. In this study, a novel nonwoven-based gauze dressing coated with quaternized chitosan/tannic acid (QCS/TA), based on electrostatic interaction and hydrogen bonding, was successfully prepared using a spray-assisted layer-by-layer assembly method. The bio-based nonwoven dressing, assembled with multiple interlacing bilayers, demonstrated outstanding antimicrobial properties, eliminating 99.99 % of Staphylococcus aureus (S. aureus) and 85 % of Escherichia coli (E. coli). Compared to the pristine nonwoven dressing, the QCS/TA-coated nonwoven dressing scavenged >85 % of the surrounding radicals within 2 h. Additionally, the nonwoven dressing exhibits excellent coagulation properties. Notably, the facile spraying procedure preserved most of the softness and breathability of the nonwoven substrate. After the deposition of seven bilayers, the bending stiffness and drape coefficient increased by only 37.63 % and 3.85 %, respectively, while the air permeability and moisture permeability reached 1712 mm/s and 3683.58 g/m2/d, respectively. This bio-based nonwoven dressing, derived from safe and non-toxic ingredients, holds promise as the next generation of multifunctional gauze dressings.

Development of AgNPs-PVP/TPU based flexible strain sensors for structural health monitoring of composite structures

Real-time in-stu structural health monitoring (SHM) of composite structure developed through highly sensitive and flexible smart sensors based on colloidal solution of Silver Nano Particles (AgNPs). Synthesis of AgNPs through chemical reduction method by citrate and then in Haxen phase transferred by using surfactant Cetyltrimethylammonium bromide (CTAB). Colloidal solution of AgNPs-Haxen and Polyvinylpyrrolidone (PVP) - Haxen has been followed by mixed, calcined and deposited that thick paste on flexible Thermoplastic Polyurethane (TPU) film. These sensors become more sensitive than metallic foil made sensors and farther this sensor pasted on polymer composite for monotonic loading like tensile loading. The data extracted from sensors was monitored effectively by data acquisitioning technique using Keithley KUSB-3100. This research based on chemical synthesis of metallic nanoparticles like silver, its functionalization, protection of these nanoparticles from environment by capping agents and by creating inert atmosphere respectively. Then these functionalized capped nanoparticles are embedded on the surface of thermoplastic Urethane (TPU) film to make piezo resistive semi conductive strips which serve as flexible strain gauge/smart sensor. One other technique is also being used to make sensor is that colloidal solution of metallic Nanoparticles sprays over TPU substrate using Connective Self Assembly (CSA) method. The sensor then properly attached to Glass fabric reinforced polymer (GFRP) composite and calibrated using data acquisitioning (DAQ) under different mode of testing.

An Improvement of Hand Press Machine by Design for Manufacturing and Assembly (DFMA) Methodology

This research consists of the analysis of hand press machine selected using the Design for Manufacturing and Assembly (DFMA) method. DFMA is a method that combines both Design for Manufacturing (DFM) and Design for Assembly (DFA) techniques. It has the purpose to make improvements on the existing product by implementing DFMA to reduce number of components, time, and cost. The combination of hand press machine and a die cutting tool has been an effective tool to produce and replicate identical designs in the shortest time. The main objective of this research is to develop a Hand Press Machine that exhibits superior design efficiency and reduced manufacturing costs compared to the original design. To achieve this, the chosen existing model, the WUTA Pro Leather Cutting Machine, was remodelled using SolidWorks 2022 software. The original design of the Hand Press Machine had a design efficiency of 25.89%. However, the improved design achieved a significantly higher design efficiency of 36.56%, representing an increase of 10.67%. To attain this improvement, four modifications were implemented. One notable achievement in the improved design was a reduction in the total number of parts. The original design comprised 52 parts, whereas the improved design successfully reduced this to 34 parts, resulting in a reduction of 18 parts. The cost analysis, based on total absorption cost, revealed that the manufacturing cost of the original design was estimated at $362.01 for 18 manufactured parts. In contrast, the improved design was able to achieve a cost reduction, with an estimated manufacturing cost of around $339.16 for 16 manufactured parts. This indicates a cost reduction of $22.85 between the two models.