Assembly Methodology Research Articles

Redesign methodology for mechanical assembly

Design for assembly is the concept of carrying out critical thought early in the design stage to create assembly easement at the production stage. In the aerospace industry, products have very long lives, frequently being optimised rather than introducing new products. This has meant older products, which are stable income generators, have not benefited from the latest design for assembly methods and manufacturing technology suffers from obsolescence. It has been established that a large percentage of overall product cost is determined at the design stage; thus, existing products suffer from preloaded costs. This paper takes existing design for assembly methodologies and analyses them with respect to the unique challenges involved in legacy product redesign. Several novel factors that contribute to redesign analysis are identified such obsolescence impact and a holistic operation difficulty assessment. A tool is developed to identify potential redesign for assembly projects. The tool is demonstrated through the application of real data and comparing against business decisions. The tool was found to provide a strong indication of where profitable projects may be launched.

Design for Additive Manufacturing, to produce assembled products, by SLS

The paper presents a new methodology on how to design a product, which could be produced directly as an assembly, instead of manufacturing all individual parts, to be assembled after words, in a classical manner. A detailed case study is presented, on how the product’s structure could be simplified, the number of the components being drastically reduced. The theoretical Design for Assembly (DFA) methodology was tested and validated, by manufacturing the physical products, using the Selective Laser Sintering (SLS) machine.

Macroscopic supramolecular assembly to fabricate multiplexed DNA patterns for potential application in DNA chips.

Macroscopic supramolecular assembly (MSA) is a newly established methodology to construct supramolecular materials directly from large building blocks. Demonstrations of MSA for various functions are urgently needed to advance MSA from fundamental studies to practical uses. Here we propose the fabrication of DNA microarrays by combining MSA and magnetic-assisted localization.

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker.

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications.

The influence of trematode parasite burden on gene expression in a mammalian host.

BackgroundParasites can profoundly impact their hosts and are responsible for a plethora of debilitating diseases. To identify global changes in host gene expression related to parasite infection, we sequenced, assembled, and annotated the liver transcriptomes of Balb/cj mice infected with the trematode parasite Schistosoma mansoni and compared the results to uninfected mice. We used two different methodologies (i.e. de novo and reference guided) to evaluate the influence of parasite sequences on host transcriptome assembly.ResultsOur results demonstrate that the choice of assembly methodology significantly impacted the proportion of parasitic reads detected from the host library, yet the presence of non-target (xenobiotic) sequences did not create significant structural errors in the assembly. After removing parasite sequences from the mouse transcriptomes, we analyzed host gene expression under different parasite infection levels and observed significant differences in the associated immunologic and metabolic responses based on infection level. In particular, genes associated with T–helper type 1 (Th–1) and T–helper type 2 (Th–2) were up-regulated in infected mice whereas genes related to amino acid and carbohydrate metabolism were down-regulated in infected mice. These changes in gene expression scale with infection status and likely impact the evolutionary fitness of hosts.ConclusionsOverall, our data indicate that a) infected mice reduce the expression of key metabolic genes in direct proportion to their infection level; b) infected mice similarly increase the expression of key immune genes in response to infection; c) patterns of gene expression correspond to the pathological symptoms of schistosomiasis; and d) identifying and filtering out non-target sequences (xenobiotics) improves differential expression prediction. Our findings identify parasite targets for RNAi or other therapies and provide a better understanding of the pathology and host immune repertoire involved in response to S. mansoni infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2950-5) contains supplementary material, which is available to authorized users.

Gemcitabine-loaded and antibody-tagged superparamagnetic iron oxide nanoparticles as targeted drug vehicles in pancreatic cancer cell lines

S. Nandi, P. D. Sykes, E. Hasan, C. Rubbi, M. Barrow, J. P. Neoptolemos, E. Costello, M. Rosseinsky and C. M. Halloran University of Liverpool, UK Aims: Despite advances in the surgical management and adjuvant chemotherapy, pancreatic cancer still has a very poor prognosis. Nanotechnology provides a novel approach for targeted drug delivery, possibly reducing the offset effects of systemic chemotherapy. Superparamagnetic iron oxide nanoparticles (SPIONs) are inorganic particles that can be functionalised as targeted drug vehicles with a stealth polymer coating and a specific antibody tag to recognise appropriate antigen expressing cells. Our aim is to develop and investigate the effects of SPIONs capable of targeted cell death of pancreatic cells by release of its chemotherapy payload. Methods: Micellar SPIONs, incorporating a gemcitabine pro-drug, conjugated to isotype and anti-CA19.9 antibodies (NP:CA19.9) were manufactured using self assembly methodology. Cellular uptake was assessed using transmission electron and co-localisation fluorescent microscopy. Antigen expression of cell lines was determined using indirect immunofluorescence. Antibody targeting was assessed using EZ4U cytotoxicity assay in BxPC-3 (Ca-19-9 +ve) and MiaPaCa-2 (Ca-19-9 -ve) cell lines. Results: Endocytosis of the SPIONs was demonstrated by their presence in endosomes and corroborated by colocalisation analysis (Manders coefficient = 0.92). The IC50 of gemcitabine was significantly improved using a nanohybrid attached with specific antibody targeting in BxPC-3 cells (10.245I/4 M vs 5.143I /4 M) [p < 0.001] but absent in MiaPaCa-2 cells (2.322I/4 M vs 2.486I /4 M) [n = 3]. Conclusions: We have developed a novel nanohybrid to target antigen expressing pancreatic cancer cells using a specific antibody tag. When loaded with modified gemcitabine, these SPIONs act as pH-triggered delivery vehicles capable of intracellular drug release. This could reduce off target effects leading to increased chemotherapy agent efficacy and offer the prospect for new treatments in pancreatic cancer.

HGA: de novo genome assembly method for bacterial genomes using high coverage short sequencing reads.

BackgroundCurrent high-throughput sequencing technologies generate large numbers of relatively short and error-prone reads, making the de novo assembly problem challenging. Although high quality assemblies can be obtained by assembling multiple paired-end libraries with both short and long insert sizes, the latter are costly to generate. Recently, GAGE-B study showed that a remarkably good assembly quality can be obtained for bacterial genomes by state-of-the-art assemblers run on a single short-insert library with very high coverage.ResultsIn this paper, we introduce a novel hierarchical genome assembly (HGA) methodology that takes further advantage of such very high coverage by independently assembling disjoint subsets of reads, combining assemblies of the subsets, and finally re-assembling the combined contigs along with the original reads.ConclusionsWe empirically evaluated this methodology for 8 leading assemblers using 7 GAGE-B bacterial datasets consisting of 100 bp Illumina HiSeq and 250 bp Illumina MiSeq reads, with coverage ranging from 100x– ∼200x. The results show that for all evaluated datasets and using most evaluated assemblers (that were used to assemble the disjoint subsets), HGA leads to a significant improvement in the quality of the assembly based on N50 and corrected N50 metrics.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2515-7) contains supplementary material, which is available to authorized users.

Material computation—4D timber construction: Towards building-scale hygroscopic actuated, self-constructing timber surfaces

The implementation of active and responsive materials in architecture and construction allows for the replacement of digitally controlled mechanisms with material-based systems that can be designed and programmed with the capacity to compute and execute a behavioral response. The programming of such systems with increasingly specific response requires a material-driven computational design and fabrication strategy. This research presents techniques and technologies for significantly upscaling hygroscopically actuated timber-based systems for use as self-constructing building surfaces. The timber’s integrated hygroscopic characteristics combined with computational design techniques and existing digital fabrication methods allow for a designed processing and reassembly of discrete wood elements into large-scale multi element bilayer surfaces. This material assembly methodology enables the design and control of the encoded direction and magnitude of humidity-actuated responsive curvature at an expanded scale. Design, simulation, and material assembly tests are presented together with formal and functional configurations that incorporate self-constructing and self-rigidizing surface strategies. The presented research and prototypes initiate a shift toward a large-scale, self-construction methodology.

A threefold interpenetrated two-dimensional zinc(II) supramolecular architecture based on 3-nitrobenzoic acid and 4,4'-bipyridine.

With regard to crystal engineering, building block or modular assembly methodologies have shown great success in the design and construction of metal-organic coordination polymers. The critical factor for the construction of coordination polymers is the rational choice of the organic building blocks and the metal centre. The reaction of Zn(OAc)2·2H2O (OAc is acetate) with 3-nitrobenzoic acid (HNBA) and 4,4'-bipyridine (4,4'-bipy) under hydrothermal conditions produced a two-dimensional zinc(II) supramolecular architecture, catena-poly[[bis(3-nitrobenzoato-κ(2)O,O')zinc(II)]-μ-4,4'-bipyridine-κ(2)N:N'], [Zn(C7H4NO4)2(C10H8N2)]n or [Zn(NBA)2(4,4'-bipy)]n, which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction analysis. The Zn(II) ions are connected by the 4,4'-bipy ligands to form a one-dimensional zigzag chain and the chains are decorated with anionic NBA ligands which interact further through aromatic π-π stacking interactions, expanding the structure into a threefold interpenetrated two-dimensional supramolecular architecture. The solid-state fluorescence analysis indicates a slight blue shift compared with pure 4,4'-bipyridine and HNBA.

Integration of DFE and DFMA for the sustainable development of an automotive component

The recent developments in manufacturing organizations recognize sustainability as an important value addition for survival in the competitive scenario. The design engineers are in search of approaches for creating environmental conscious products. The purpose of this paper is to report a research carried out for ensuring sustainable product design by the integration of Design for Environment (DFE) and Design for Manufacture and Assembly (DFMA) methodologies. In this context, this paper reports a case study carried out in an automotive component. The candidate product is the charge alternator pulley. The existing pulley has been created using Computer Aided Design. Then sustainability analysis was conducted on the existing component for determining environmental impact. This is followed by the engineering analysis of the component using ANSYS. Then conceptual design changes were developed in the proposed product using DFMA concept. Then the environmental impact has been evaluated in terms of carbon footprint, energy consumption and air/water impacts on proposed product. It has been found that the optimized pulley design possesses minimal environmental impact. The result of the case study indicated that the integration of DFE and DFMA concept could initiate new developments in sustainable designs with minimal impact to the environment and it also reduces the product cost.

ChemInform Abstract: Benzylation of Arenes with Benzyl Halides Synergistically Promoted by in situ Generated Superacid Boron Trifluoride Monohydrate and Tetrahaloboric Acid.

Abstract To examine the assembly methodology of diarylmethanes, a benzylation of (hetero)arenes with benzyl halides has been developed and various diarylmethanes were furnished with yields of up to 98% and regioselectivities of up to >99%. The complexation of the by-product halogen hydride with BF3·OEt2 generated the Bronsted acid BF3·HX (HBF3X, X=Cl or Br) in situ to synergistically promote the benzylation.

Benzylation of arenes with benzyl halides synergistically promoted by in situ generated superacid boron trifluoride monohydrate and tetrahaloboric acid

To examine the assembly methodology of diarylmethanes, a benzylation of (hetero)arenes with benzyl halides has been developed and various diarylmethanes were furnished with yields of up to 98% and regioselectivities of up to >99%. The complexation of the by-product halogen hydride with BF3·OEt2 generated the Bronsted acid BF3·HX (HBF3X, X=Cl or Br) in situ to synergistically promote the benzylation.

The landscape of long noncoding RNAs in the human transcriptome.

Long noncoding RNAs (lncRNAs) are emerging as important regulators of tissue physiology and disease processes including cancer. To delineate genome-wide lncRNA expression, we curated 7,256 RNA sequencing (RNA-seq) libraries from tumors, normal tissues and cell lines comprising over 43 Tb of sequence from 25 independent studies. We applied ab initio assembly methodology to this data set, yielding a consensus human transcriptome of 91,013 expressed genes. Over 68% (58,648) of genes were classified as lncRNAs, of which 79% were previously unannotated. About 1% (597) of the lncRNAs harbored ultraconserved elements, and 7% (3,900) overlapped disease-associated SNPs. To prioritize lineage-specific, disease-associated lncRNA expression, we employed non-parametric differential expression testing and nominated 7,942 lineage- or cancer-associated lncRNA genes. The lncRNA landscape characterized here may shed light on normal biology and cancer pathogenesis and may be valuable for future biomarker development.

Software-assisted stacking of gene modules using GoldenBraid 2.0 DNA-assembly framework.

GoldenBraid (GB) is a modular DNA assembly technology for plant multigene engineering based on type IIS restriction enzymes. GB speeds up the assembly of transcriptional units from standard genetic parts and facilitates the stacking of several genes within the same T-DNA in few days. GBcloning is software-assisted with a set of online tools. The GBDomesticator tool assists in the adaptation of DNA parts to the GBstandard. The combination of GB-adapted parts to build new transcriptional units is assisted by the GB TU Assembler tool. Finally, the assembly of multigene modules is simulated by the GB Binary Assembler. All the software tools are available at www.gbcloning.org . Here, we describe in detail the assembly methodology to create a multigene construct with three transcriptional units for polyphenol metabolic engineering in plants.

A framework of measurement assisted assembly for wing-fuselage alignment based on key measurement characteristics

Wide employments of large scale digital metrologies have promoted the development of digital aircraft assembly technologies, which are changing traditional processes of wing-fuselage alignment to high precision and more efficient digital alignment based on measurement assisted assembly (MAA). MAA is a systematic technique and relies on the integration of digital measurement with assembly process, which is not only the integration of operations, but also data fusion and propagation from product design, through digital inspection to components assembly. In order to direct and support the applications of advanced approaches in MAA for wing-fuselage alignment, a novel framework of measurement assisted assembly methodology is proposed to realise the process integration and data fusion based on key measurement characteristics (KMCs). Firstly, definition, classification and mathematical model of KMCs are presented; then, the framework is constructed on the basis of integrated process model, measurement data model and data process kernel. Finally, a case of wing-fuselage alignment simulation is carried out to illuminate the application of measurement assisted assembly technique with the framework. [Received 28 April 2013; Revised 25 February 2014; Accepted 26 April 2014]

Mixed mosaic membranes prepared by layer-by-layer assembly for ionic separations.

Charge mosaic membranes, which possess distinct cationic and anionic domains that traverse the membrane thickness, are capable of selectively separating dissolved salts from similarly sized neutral solutes. Here, the generation of charge mosaic membranes using facile layer-by-layer assembly methodologies is reported. Polymeric nanotubes with pore walls lined by positively charged polyethylenimine moieties or negatively charged poly(styrenesulfonate) moieties were prepared via layer-by-layer assembly using track-etched membranes as sacrificial templates. Subsequently, both types of nanotubes were deposited on a porous support in order to produce mixed mosaic membranes. Scanning electron microscopy demonstrates that the facile deposition techniques implemented result in nanotubes that are vertically aligned without overlap between adjacent elements. Furthermore, the nanotubes span the thickness of the mixed mosaic membranes. The effects of this unique nanostructure are reflected in the transport characteristics of the mixed mosaic membranes. The hydraulic permeability of the mixed mosaic membranes in piezodialysis operations was 8 L m(-2) h(-1) bar(-1). Importantly, solute rejection experiments demonstrate that the mixed mosaic membranes are more permeable to ionic solutes than similarly sized neutral molecules. In particular, negative rejection of sodium chloride is observed (i.e., the concentration of NaCl in the solution that permeates through a mixed mosaic membrane is higher than in the initial feed solution). These properties illustrate the ability of mixed mosaic membranes to permeate dissolved ions selectively without violating electroneutrality and suggest their utility in ionic separations.

DNA Assembly Tools and Strategies for the Generation of Plasmids.

Since the discovery of restriction enzymes and the generation of the first recombinant DNA molecule over 40 years ago, molecular biology has evolved into a multidisciplinary field that has democratized the conversion of a digitized DNA sequence stored in a computer into its biological counterpart, usually as a plasmid, stored in a living cell. In this article, we summarize the most relevant tools that allow the swift assembly of DNA sequences into useful plasmids for biotechnological purposes. We cover the main components and stages in a typical DNA assembly workflow, namely in silico design, de novo gene synthesis, and in vitro and in vivo sequence assembly methodologies.

Synthesis and characterization of perylene diimide based molecular multilayers using CuAAC: towards panchromatic assemblies

Three perylene diimides (PDI) were synthesized with propargyl groups at the diimide positions to enable the fabrication of molecular multilayer thin films via sequential copper(I) catalyzed azide-alkyne cycloaddition (CuAAC) coupling reactions in a layer-by-layer (LbL) fashion. The new PDIs with phenoxy (PhO-PDI), dodecylthiol (Thiol-PDI), and pyrrolidine (Pyrr-PDI) substituents in bay positions have optical absorption spectra that span a large portion of the visible region. Multilayer growth on 11-azidoundecylsiloxane coated silica glass and indium tin oxide (ITO) surfaces was demonstrated up to 10 bilayers of each PDI with 1,3,5-tris(azidomethyl)-benzene (N3Mest) via optical and infrared spectroscopy. Polarized UV-visible absorption measurements showed a strong dependence on the orientation of the film in the light path and was consistent with a preferential orientation of the PDI molecules in the film at 40–42° with respect to the substrate surface. Grazing-angle attenuated total reflectance (GATR) infrared spectra of the films show an increase in content of unreacted azides during multilayer growth from N3Mest as a result of the smaller molecular footprint as compared to the PDI components. Electrochemical scans of the multilayer films grown on ITO exhibited reversible two-electron reduction waves for the PDIs with linear increases in charge with bilayer growth. The electrochemically derived surface coverages of PDIs averaged 1.2–1.3 × 1014 molecules per cm2 for each layer added to the multilayer films. The flexibility of the CuAAC based LbL assembly methodology is highlighted by the assembly of a mixed multilayer film containing five layers of each PDI, resulting in a panchromatic film that is a summation of individual chromophores.

SSPACE-LongRead: scaffolding bacterial draft genomes using long read sequence information

BackgroundThe recent introduction of the Pacific Biosciences RS single molecule sequencing technology has opened new doors to scaffolding genome assemblies in a cost-effective manner. The long read sequence information is promised to enhance the quality of incomplete and inaccurate draft assemblies constructed from Next Generation Sequencing (NGS) data.ResultsHere we propose a novel hybrid assembly methodology that aims to scaffold pre-assembled contigs in an iterative manner using PacBio RS long read information as a backbone. On a test set comprising six bacterial draft genomes, assembled using either a single Illumina MiSeq or Roche 454 library, we show that even a 50× coverage of uncorrected PacBio RS long reads is sufficient to drastically reduce the number of contigs. Comparisons to the AHA scaffolder indicate our strategy is better capable of producing (nearly) complete bacterial genomes.ConclusionsThe current work describes our SSPACE-LongRead software which is designed to upgrade incomplete draft genomes using single molecule sequences. We conclude that the recent advances of the PacBio sequencing technology and chemistry, in combination with the limited computational resources required to run our program, allow to scaffold genomes in a fast and reliable manner.

Design for Manufacturing and Assembly Cost Estimate Methodology for Transportation Fuel Cell Systems

This article presents a design for manufacturing and assembly (DFMA) methodology for estimating the capital costs of new, emerging energy technologies built at varying rates of mass-production. The methodology consists of four major steps: (1) System Conceptual Design, (2) System Physical Design, (3) Cost Modeling, and (4) Continuous Improvement to Reduce Cost. The article describes the application of this methodology to a specific case study of automotive fuel cell systems (FCSs). Because any alternative automotive technology must compete with the very mature and widespread gasoline internal combustion engine, it is vitally important to identify the performance, design, and manufacturing conditions needed to reduce automotive FCS costs. Thus, a DFMA-style analysis is applied to the cost to manufacture a polymer electrolyte membrane (PEM) FCS for cars, at varying rates of production (between 1,000 and 500,000 vehicles per year). The results of this kind of DFMA-style analysis can be used to elucidate key cost drivers at varying levels of production for new energy technologies.