Thread Structure Research Articles

Preparation and Characterization of Artificial Spider Silk Produced through Microchannel Techniques

Spider silk (SS) is naturally tough; however, it turns soft when wet by water. Spiders produce high-quality silk threads by adjusting the molecular assemblage of SS-proteins and the arrangements structure of threads and recombinant spider dragline silk (RSDS). The general wet spinning techniques for producing recombinant spidroins results in uncorrected explanation to the natural spinning technique. In this study, we use tailored-SS with relative low molecular weight of 47 kD to produce a water-soluble RSDS protein. We built a microfluidic ship and used it to spun SS using aqueous solutions-micro-technique (wet spinning). This was done in order to mimic the spider-spinning processes using a steady post-spin drawing process. We succeeded to produce assemblies of spidroins with fibril structure. Then, compact constituting of micro-threads followed these wet spinning processes. Wet spinning was followed by improving the orientation, crystalline structure, and fibril melting of the hierarchical structure. The initial mechanical characterization (tensile strength) of the RSDSs attained about 510 MPa with respective extension 44%.

The Regulatory Protein RosR Affects Rhizobium leguminosarum bv. trifolii Protein Profiles, Cell Surface Properties, and Symbiosis with Clover.

Rhizobium leguminosarum bv. trifolii is capable of establishing a symbiotic relationship with plants from the genus Trifolium. Previously, a regulatory protein encoded by rosR was identified and characterized in this bacterium. RosR possesses a Cys2-His2-type zinc finger motif and belongs to Ros/MucR family of rhizobial transcriptional regulators. Transcriptome profiling of the rosR mutant revealed a role of this protein in several cellular processes, including the synthesis of cell-surface components and polysaccharides, motility, and bacterial metabolism. Here, we show that a mutation in rosR resulted in considerable changes in R. leguminosarum bv. trifolii protein profiles. Extracellular, membrane, and periplasmic protein profiles of R. leguminosarum bv. trifolii wild type and the rosR mutant were examined, and proteins with substantially different abundances between these strains were identified. Compared with the wild type, extracellular fraction of the rosR mutant contained greater amounts of several proteins, including Ca2+-binding cadherin-like proteins, a RTX-like protein, autoaggregation protein RapA1, and flagellins FlaA and FlaB. In contrast, several proteins involved in the uptake of various substrates were less abundant in the mutant strain (DppA, BraC, and SfuA). In addition, differences were observed in membrane proteins of the mutant and wild-type strains, which mainly concerned various transport system components. Using atomic force microscopy (AFM) imaging, we characterized the topography and surface properties of the rosR mutant and wild-type cells. We found that the mutation in rosR gene also affected surface properties of R. leguminosarum bv. trifolii. The mutant cells were significantly more hydrophobic than the wild-type cells, and their outer membrane was three times more permeable to the hydrophobic dye N-phenyl-1-naphthylamine. The mutation of rosR also caused defects in bacterial symbiotic interaction with clover plants. Compared with the wild type, the rosR mutant infected host plant roots much less effectively and its nodule occupation was disturbed. At the ultrastructural level, the most striking differences between the mutant and the wild-type nodules concerned the structure of infection threads, release of bacteria, and bacteroid differentiation. This confirms an essential role of RosR in establishment of successful symbiotic interaction of R. leguminosarum bv. trifolii with clover plants.

Extraordinary structure and properties of mussel byssus protein fibers

A naturally available single protein fiber that is stiff and strong at one end but at the same time highly flexible with moderate strength at the other end is quite exceptional. Such exceptional protein fibers called byssus threads are produced by mussels. A unique arrangement of collagen proteins along the length of the fibers and a specific amount and distribution of the β-sheet and α-helix regions provide extraordinary properties to byssus threads. Due to the unique configuration of the threads and a distinct adhesive plaque, mussels are able to adhere to substrates and withstand large amounts of external forces. However, significant variations in composition and tensile properties exist between the mussels threads obtained from different species and even along the length of a single byssal thread. Similarly, environmental conditions such as the presence of salt water and chemicals affect the properties of the fibers. Extensive studies have been done to understand the composition, the structure and the properties of the byssal threads. This review provides an insight into the unique structure and properties of the byssal threads and discusses the potential of developing biomimetic materials based on the mussel byssal threads.

FORMATION AND PLASMA CIRCULATION OF SOLAR PROMINENCES

ABSTRACT Solar prominences are long-lived cool and dense plasma curtains in the hot and rarefied outer solar atmosphere or corona. The physical mechanism responsible for their formation and especially for their internal plasma circulation has been uncertain for decades. The observed ubiquitous downflows in quiescent prominences are difficult to interpret because plasma with high conductivity seems to move across horizontal magnetic field lines. Here we present three-dimensional numerical simulations of prominence formation and evolution in an elongated magnetic flux rope as a result of in situ plasma condensations fueled by continuous plasma evaporation from the solar chromosphere. The prominence is born and maintained in a fragmented, highly dynamic state with continuous reappearance of multiple blobs and thread structures that move mainly downward, dragging along mass-loaded field lines. The circulation of prominence plasma is characterized by the dynamic balance between the drainage of prominence plasma back to the chromosphere and the formation of prominence plasma via continuous condensation. Plasma evaporates from the chromosphere, condenses into the prominence in the corona, and drains back to the chromosphere, establishing a stable chromosphere–corona plasma cycle. Synthetic images of the modeled prominence with the Solar Dynamics Observatory Atmospheric Imaging Assembly closely resemble actual observations, with many dynamical threads underlying an elliptical coronal cavity.

Unpicking the signal thread of the sector web spider Zygiella x-notata.

Remote sensing allows an animal to extend its morphology with appropriate conductive materials and sensors providing environmental feedback from spatially removed locations. For example, the sector web spider Zygiella x-notata uses a specialized thread as both a structural bridge and signal transmitter to monitor web vibrations from its retreat at the web perimeter. To unravel this model multifunctional system, we investigated Zygiella's signal thread structure with a range of techniques, including tensile testing, laser vibrometry, electron microscopy and behavioural analysis. We found that signal threads varied significantly in the number of filaments; a result of the spider adding a lifeline each time it runs along the bridge. Our mechanical property analysis suggests that while the structure varies, its normalized load does not. We propose that the signal thread represents a complex and fully integrated multifunctional structure where filaments can be added, thus increasing absolute load-bearing capacity while maintaining signal fidelity. We conclude that such structures may serve as inspiration for remote sensing design strategies.

Effective Techniques for Static Race Detection in Java Parallel Loops

Despite significant progress in recent years, the important problem of static race detection remains open. Previous techniques took a general approach and looked for races by analyzing the effects induced by low-level concurrency constructs (e.g., java.lang.Thread). But constructs and libraries for expressing parallelism at a higher level (e.g., fork-join, futures, parallel loops) are becoming available in all major programming languages. We claim that specializing an analysis to take advantage of the extra semantic information provided by the use of these constructs and libraries improves precision and scalability. We present I te R ace , a set of techniques that are specialized to use the intrinsic thread, safety, and dataflow structure of collections and of the new loop parallelism mechanism introduced in Java 8. Our evaluation shows that I te R ace is fast and precise enough to be practical. It scales to programs of hundreds of thousands of lines of code and reports very few race warnings, thus avoiding a common pitfall of static analyses. In five out of the seven case studies, I te R ace reported no false warnings. Also, it revealed six bugs in real-world applications. We reported four of them: one had already been fixed, and three were new and the developers confirmed and fixed them. Furthermore, we evaluate the effect of each specialization technique on the running time and precision of the analysis. For each application, we run the analysis under 32 different configurations. This allows to analyze each technique's effect both alone and in all possible combinations with other techniques.

Cribellate thread production in spiders: Complex processing of nano-fibres into a functional capture thread

Spider silk production has been studied intensively in the last years. However, capture threads of cribellate spiders employ an until now often unnoticed alternative of thread production. This thread in general is highly interesting, as it not only involves a controlled arrangement of three types of threads with one being nano-scale fibres (cribellate fibres), but also a special comb-like structure on the metatarsus of the fourth leg (calamistrum) for its production. We found the cribellate fibres organized as a mat, enclosing two parallel larger fibres (axial fibres) and forming the typical puffy structure of cribellate threads. Mat and axial fibres are punctiform connected to each other between two puffs, presumably by the action of the median spinnerets. However, this connection alone does not lead to the typical puffy shape of a cribellate thread. Removing the calamistrum, we found a functional capture thread still being produced, but the puffy shape of the thread was lost. Therefore, the calamistrum is not necessary for the extraction or combination of fibres, but for further processing of the nano-scale cribellate fibres. Using data from Uloborus plumipes we were able to develop a model of the cribellate thread production, probably universally valid for cribellate spiders.

Design and analysis of the glass fiber composite truss beam structure

To exert the corrosion-resistant characteristics of the composite materials, which have overcome the characteristics of low modulus of the truss structure design. We designed a new kind of beam-slab structure and it can be applied to the desulfurization and denitration tower. The kingpost is undertook by four successive FRP profiles and nodes connected by hough; both ends are connected by a rod with the thread structure. This research analyzed the structure of the finite element, and the result comes out that the stress, the strain and distortion of the whole kingpost, are meet regulatory requirements as well.

Ion beam analysis of golden threads from Romanian medieval textiles

In this study, metal threads from Romanian religious embroideries and precious velvet brocades dated from 15th to 18th century were analyzed by using IBA methods (PIXE and RBS) which, in comparison to the traditional analytical techniques (XRF, EDS), allowed the detection of their structures and accurate identification of the trace elements (detection limits of few tens of ppm). PIXE results confirmed that both types of the metal threads studied – wires and strips – have layered structures being made of fine silver, refined by cupellation, and gilded most probably with pure gold, and not of Au–Ag alloy, or gilded Ag–Cu alloy or Au–Ag–Cu alloy, as resulted from the previously performed SEM-EDS analysis. Trace elements of historical interest like lead, mercury and bismuth have been also possible to be detected by PIXE. The resulting elemental maps allowed us to identify the areas from which the metal thread structure and quantitative composition could be accurately determined. RBS measurements revealed that the gilding layer is separated from the silver bulk by an interface layer resulting through atomic diffusion of silver into the gold, which lead to the conclusion that the methods used for gilding were probably either the diffusion bonding or the fire gilding. The gilding layers thicknesses were estimated by PIXE with the GUPIX software and also determined from RBS measurements.

Treating the untreatable in art and heritage materials: ultrafast laser cleaning of "cloth-of-gold".

Laser cleaning provides art and heritage conservators with an alternative means to restore objects when traditional chemical and mechanical methods are not viable. However, long (>nanosecond) laser pulses can cause unwanted damage from photothermal processes and provide limited control over ablation depth. Ultrashort (<picosecond) pulse lasers are emerging as a more appropriate tool for cleaning historic artifacts because of their unique ability to avoid heat- and shock-wave generation, thus minimizing collateral damage of the underlayers, and to remove material with near-nanometer precision. Here we demonstrate the effectiveness of ultrashort pulses by cleaning 19th century military gold braid without any detrimental effects on the gold foil or the underlying silk thread structure. The results are compared with nanosecond-pulse laser treatment that damages the surface structure. By introducing in situ feedback control of the laser ablation via laser-induced breakdown spectroscopy (LIBS) monitoring of the ablated plume, we are able to halt the cleaning process just as the contaminant layer is completely removed. This technique allows ultrafast laser ablation to extend the armory of conservation treatments, enabling restoration of a range of complex and fragile heritage objects previously untreatable by conventional means.

Research on bolt pre-tightening and relaxation mechanism under transverse load

In order to predict the bolt’s stress distribution under the pre-tightening state and the loosening process under the transverse load, a 3D model considering the bolt thread structure was established by finite element method (FEM). In this study, the looseness effect of transverse load amplitude, the friction coefficient of the bolt head load bearing surface and the thread contact surface are mainly studied. The result indicated that the stress under bolt pre-tightening is mainly concentrated on the contact part of the bolt’s head and bar. At the contact area of the load threads at one end and the transition part between the bolt bar and the thread, the stress and axial direction of the thread part are offset. Under the transverse displacement load, the sliding of the bolt can be divided into three stages: full contact, viscous contact, and full slip. The numerical model of bolt relaxation obtained in this paper can provide reference for the application, checking and prediction of threaded fasteners.

Pattern-Based Verification for Multithreaded Programs

Pattern-based verification checks the correctness of program executions that follow a given pattern , a regular expression over the alphabet of program transitions of the form w 1 * … w n * . For multithreaded programs, the alphabet of the pattern is given by the reads and writes to the shared storage. We study the complexity of pattern-based verification for multithreaded programs with shared counters and finite variables. While unrestricted verification is undecidable for abstracted multithreaded programs with recursive procedures and PSPACE-complete for abstracted multithreaded while-programs (even without counters), we show that pattern-based verification is NP-complete for both classes, even in the presence of counters. We then conduct a multiparameter analysis to study the complexity of the problem on its three natural parameters (number of threads+counters+variables, maximal size of a thread, size of the pattern) and on two parameters related to thread structure (maximal number of procedures per thread and longest simple path of procedure calls). We present an algorithm that for a fixed number of threads, counters, variables, and pattern size solves the verification problem in st O ( lsp + ⌈ log ( pr +1) ⌉) time, where st is the maximal size of a thread, pr is the maximal number of procedures per thread, and lsp is the longest simple path of procedure calls.

Application of Simulation Technology on the Design of One Special Expandable Tubular Thread

(minimum 200words, maximum 300-500words) The solid expandable tubular technology is one of the most important ones which play key role in 21st century’s oil drilling industry. The expandable thread connection is one of the key factor of the technology which decide the success or failure of expansion casing site construction. Finite element simulation can help analyze the feasibility effectively on expandable casing thread connection structure design and save a lot of material and financial resources. According to a special expansion casing thread which with single hook thread characteristics, metal seal cylinder and seal ring, this paper use the finite element simulation analysis method to learn the stress, strain and displacement being occurred in thread connection during the process of expansion. The finite element simulation analysis results shown that the wall thickness decreased about 0.66mm after the expansion, the maximum stress of expandable casing connection during expansion was 494 MPa which between the yield stress(ss= 380MPa) and ultimate strength(sb= 650MPa) of the casing material, the most dangerous place of thread connection was the roots of thread, there was gapless between contact surfaces of the messing thread with contact pressure during the expansion, and the rubber sealing ring kept the state with the minimum 4.64 MPa compress stress during the expansion. Through the simulation, It can come to a conclusion that the special thread structure could meet the expected connection and seal function effectively during the expansion process, which provides an important basis for the following thread processing and expansion test.

Analyzing and Mining Comments and Comment Ratings on the Social Web

An analysis of the social video sharing platform YouTube and the news aggregator Yahoo! News reveals the presence of vast amounts of community feedback through comments for published videos and news stories, as well as through metaratings for these comments. This article presents an in-depth study of commenting and comment rating behavior on a sample of more than 10 million user comments on YouTube and Yahoo! News. In this study, comment ratings are considered first-class citizens. Their dependencies with textual content, thread structure of comments, and associated content (e.g., videos and their metadata) are analyzed to obtain a comprehensive understanding of the community commenting behavior. Furthermore, this article explores the applicability of machine learning and data mining to detect acceptance of comments by the community, comments likely to trigger discussions, controversial and polarizing content, and users exhibiting offensive commenting behavior. Results from this study have potential application in guiding the design of community-oriented online discussion platforms.

Spider web in Late Cretaceous French amber (Vendée): The contribution of 3D image microscopy

Late Cretaceous amber from La Garnache (France, Vendée) contains filamentous networks that have all the characteristics of spider webs. Using methods of classic and confocal microscopy, the web architecture and the thread structure are described. The geometry of the webs preserved in amber is presented in 3D imaging. Unlike most of the spider webs identified in amber, there are no regular radiating webs growing in two dimensions characteristic of the well-known orb web. A number of the characters would correspond to the apparently irregular organization of cob-type web or sheet web. By using confocal microscopy, we can highlight the preserved autofluorescence of spider silk proteins and new characters are proposed to identify the spider webs or fragments of webs in amber.

Nanostructures formed by cyclodextrin covered aminobenzophenones through supramolecular self assembly

Cyclodextrin (α and β) based nanostructures formed with 2-aminobenzophenone, 3-aminobenzophenone through the supramolecular self assembly are studied by absorption, fluorescence, time-resolved fluorescence, SEM, TEM, FT-IR, DSC, PXRD and 1H NMR. The unequal layer by layer nanosheets and nanoribbons are formed through self assembly of 3ABP/CD inclusion complexes. 2ABP/α-CD complex nanostructures show the self assembly hierarchical thread structure and β-CD complexes displays a nanobrick structure. The formation of nanostructures are prearranged to HO⋯H, NH2⋯O and H2N⋯H intermolecular hydrogen bond between individual complexes. The absorption and fluorescence spectral changes explicit formation of 1:1 inclusion complexes and solvent study demonstrate the ESIPT and TICT present in both molecules. The thermodynamic parameters (ΔH, ΔG and ΔS) of 2ABP and 3ABP molecule and the inclusion complexes were determined from semiempirical PM3 calculations.

Self-Assembly Enhances the Strength of Fibers Made from Vimentin Intermediate Filament Proteins

Hagfish slime threads were recently established as a promising biomimetic model for efforts to produce ecofriendly alternatives to petroleum polymers. Initial attempts to make fibers from solubilized slime thread proteins fell short of achieving the outstanding mechanics of native slime threads. Here we tested the hypothesis that the high strength and toughness of slime threads arise from the ability of constituent intermediate filaments to undergo a stress-induced α-to-β transition. To do this, we made fibers from human vimentin proteins that were first allowed to self-assemble into 10 nm intermediate filaments. Fibers made from assembled vimentin hydrogels underwent an α-to-β transition when strained and exhibited improved mechanical performance. Our data demonstrate that it is possible to make materials from intermediate filament hydrogels and that mimicking the secondary structure of native hagfish slime threads using intermediate filament self-assembly is a promising strategy for improving the mechanical performance of biomimetic protein materials.

A Supervised Approach to Predict the Hierarchical Structure of Conversation Threads for Comments

User-generated texts such as comments in social media are rich sources of information. In general, the reply structure of comments is not publicly accessible on the web. Websites present comments as a list in chronological order. This way, some information is lost. A solution for this problem is to reconstruct the thread structure (RTS) automatically. RTS predicts a semantic tree for the reply structure, useful for understanding users' behaviours and facilitating follow of the actual conversation streams. This paper works on RTS task in blogs, online news agencies, and news websites. These types of websites cover various types of articles reflecting the real-world events. People with different views participate in arguments by writing comments. Comments express opinions, sentiments, or ideas about articles. The reply structure of threads in these types of websites is basically different from threads in the forums, chats, and emails. To perform RTS, we define a set of textual and nontextual features. Then, we use supervised learning to combine these features. The proposed method is evaluated on five different datasets. The accuracy of the proposed method is compared with baselines. The results reveal higher accuracy for our method in comparison with baselines in all datasets.

A Flexible micro-supercapacitor based on a pen ink-carbon fiber thread

A highly flexible micro-supercapacitor based on a pen ink-carbon-fiber thread structure is fabricated with excellent characteristics of lightweight, small volume, flexibility and portability. By integrating with a triboelectric nanogenarator, the micro-supercapacitors are charged and used to power LEDs, demonstrating its feasibility as an efficient storage component for self-powered micro/nanosystems.

직금·자수에 사용된 금사의 형태와 특징 비교 고찰

In the Korean literature, records of systematic gold thread manufacturing such as gold foil(金 箔匠), gold foil bonded with fabrics(付金匠), gold foil bonded with paper materials(金箋紙匠), refining gold(鍊金匠), cutting gold(裁金匠), and making gold thread(絲金匠) can be easily found. We can infer from these literatures that the Korean people used to make gold threads. However, is not existent the gold thread making technique. Thus, a research was done using 67 pieces of gold thread artifacts used in textiles craft of Korea, China and Japan. The purpose of this research was to identify the characteristics of the Korean gold thread by studying the artifacts` form classification, gold foil, glue and the base. First, gold thread is divided into flat gold thread and wrapped gold thread. Wrapped gold thread was made in more various methods such as with a paper on the flat gold thread, metal thread and wrapped gold thread with gold foil on top. Compared to the flat gold thread, wrapped gold thread uses a thread that has a thinner and wider. Through this analysis, even making of the base of the gold threads was different according to the type. Secondly, we looked into the characteristics of materials according to form structure of the gold thread. After analysis of experiment results, we could know that to attach Korean gold thread, glue and the mixture of materials such as Red soil(朱土) was also added. The kinds of the base of gold threads were identified as paper, leather and intestines. Among those materials, for paper, Korea``s Dakji, China``s Sangpiji(桑皮紙) and Jukji(竹紙) and Japan``s Anpiji(雁皮紙) seemed to have all been used, so because of the difference among countries, we can prove that Korea has also produced gold thread. By looking at the research, the base of gold threads and making features hugely vary according to the area.