Bundle Size Research Articles

Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin.

Ena/VASP tetramers are processive actin elongation factors that localize to diverse F-actin networks composed of filaments bundled by different cross-linking proteins, such as filopodia (fascin), lamellipodia (fimbrin), and stress fibers (α-actinin). Previously, we found that Ena takes approximately threefold longer processive runs on trailing barbed ends of fascin-bundled F-actin. Here, we used single-molecule TIRFM (total internal reflection fluorescence microscopy) and developed a kinetic model to further dissect Ena/VASP’s processive mechanism on bundled filaments. We discovered that Ena’s enhanced processivity on trailing barbed ends is specific to fascin bundles, with no enhancement on fimbrin or α-actinin bundles. Notably, Ena/VASP’s processive run length increases with the number of both fascin-bundled filaments and Ena “arms,” revealing avidity facilitates enhanced processivity. Consistently, Ena tetramers form more filopodia than mutant dimer and trimers in Drosophila culture cells. Moreover, enhanced processivity on trailing barbed ends of fascin-bundled filaments is an evolutionarily conserved property of Ena/VASP homologues, including human VASP and Caenorhabditis elegans UNC-34. These results demonstrate that Ena tetramers are tailored for enhanced processivity on fascin bundles and that avidity of multiple arms associating with multiple filaments is critical for this process. Furthermore, we discovered a novel regulatory process whereby bundle size and bundling protein specificity control activities of a processive assembly factor.

959: Molecular characterization of the post cesarean uterine scar

Cesarean section (CS) accounts for 31.9% of births in the United States and is associated with a 3.6-fold increase in maternal mortality, in part due to complications in future pregnancies such as uterine rupture or placenta accreta. CS technique is largely anecdotal because it is not known how the unique structure of the uterus nor CS surgical factors impact scar formation. The purpose of this study was to investigate the histologic structure and density of post-CS uterine scar. Lower uterine segment was prospectively biopsied at the time of repeat CS (n=4). Samples from a primary CS and premenopausal non-pregnant hysterectomy specimen were used for comparison. Data collected included demographic information and inter-conception interval (ICI). Biopsy specimens were formalin fixed, paraffin embedded, and sections were stained with Masson Trichome to differentiate collagen (blue) and myometrium (red/purple). Representative images were analyzed using ImageJ software. Collagen bundle thickness was quantified, and ANOVA was used to detect differences between samples. Tissue specimens were sent for 3- dimensional molecular imaging with MicroCT. Vivoquant software was used for segmentation analysis of MicroCT images. Differences in tissue density were compared using Chi-square, with significance at p<0.05. Collagen bundles were thicker and more disorganized in subjects undergoing repeat CS compared to unscarred pregnant and post-menopausal specimens (p < 0.001). The range of collagen bundle size was also wider in subjects with a shorter 29-34 month ICI compared to a longer 106-108 month ICI (2.37-23.84 mm vs 2.37-9.00 mm). MicroCT analysis revealed a heterogeneous distribution of scar density within RCS tissue samples (p < 0.001), with collagen density randomly distributed between serosal and endometrial surfaces. Post-CS scar structure is characterized by increased collagen bundle thickness compared to native uterine tissue. Scar structure is dynamic over time with more abundant and disorganized collagen bundles present earlier in the healing process, and more contracted scar over time. MicroCT analysis shows heterogeneity in scar density, even among samples of similar ICI, suggesting the importance of individual variation. Further study is needed to determine if molecular characteristics of uterine scar structure are associated with adverse pregnancy outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Micromechanical study on the origin of fiber bridging under interlaminar and intralaminar mode I failure

Fiber reinforced polymers (FRPs) subjected to mode I fracture show important toughening due to the development of large scale bridging (LSB). Experimental studies of this phenomenon in unidirectional carbon/epoxy laminates using double cantilever beam specimens, demonstrate important differences in R-curve response for inter- and intralaminar fracture. Post fracture observation of composite’s cross-section pointed out dissimilar fiber bundle size and shape, as the main origin of their differences. In the present paper, representative volume elements with the composite’s constituents, based on the actual material microstructure, and homogenized 2D finite element models were developed to study the effects of microstructure on the first stage of damage leading to LSB development in carbon/epoxy composites under mode I fracture. The differences between inter- and intralaminar fracture were investigated along with the influence of fiber dispersion and the presence of interply and intraply resin-rich zones. The numerical simulations captured different microcrack morphologies for inter- and intralaminar fracture, supporting the experimental observations, while parametric studies showed the influence of the microstructure in the formation of LSB. In particular, fiber dispersion within a ply and resin rich zone between plies play significant roles in mode I fracture and can be used to control toughening mechanisms in FRPs.

Numerical investigation of membrane oxygenation using sub-channel analysis

Purpose Better membrane oxygenators need to be developed to enable efficient gas exchange between venous blood and air. Design/methodology/approach Optimal design and analysis of such devices are achieved through mathematical modeling tools such as computational fluid dynamics (CFD). In this study, a control volume-based one-dimensional (1D) sub-channel analysis code is developed to analyze the gas exchange between the hollow fiber bundle and the venous blood. DIANA computer code, which is popular with the thermal hydraulic analysis of sub-channels in nuclear reactors, was suitably modified to solve the conservation equations for the blood oxygenators. The gas exchange between the tube-side fluid and the shell-side venous blood is modeled by solving mass, momentum and species conservation equations. Findings Simulations using sub-channel analysis are performed for the first time. As the DIANA-based approach is well known in rod bundle heat transfer, it is applied to membrane oxygenators. After detailed validations, the artificial membrane oxygenator is analyzed for different bundle sizes (L/W) and bundle porosity (epsilon) values, and oxygen saturation levels are predicted along the bundle. The present sub-channel analysis is found to be reasonably accurate and computationally efficient when compared to conventional CFD calculations. Research limitations/implications This approach is promising and has far-reaching ramifications to connect and extend a well-known rod bundle heat transfer algorithm to a membrane oxygenator community. As a variety of devices need to be analyzed, simplified approaches will be attractive. Although the 1D nature of the simulations facilitates handling complexity, it cannot easily compete with expensive and detailed CFD calculations. Practical implications This work has high practical value and impacts the design community directly. Detailed numerical simulations can be validated and benchmarked for future membrane oxygenator designs. Social implications Future membrane oxygenators can be designed and analyzed easily and efficiently. Originality/value The DIANA algorithm is popularly used in sub-channel analysis codes in rod bundle heat transfer. This efficient approach is being implemented into membrane oxygenator community for the first time.

Competition for epidermal space in the evolution of leaves with high physiological rates.

Leaves with high photosynthetic capacity require high transpiration capacity. Consequently, hydraulic conductance, stomatal conductance, and assimilation capacities should be positively correlated. These traits make independent demands on anatomical space, particularly due to the propensity for veins to have bundle sheath extensions that exclude stomata from the local epidermis. We measured density and area occupation of bundle sheath extensions, density and size of stomata and subsidiary cells, and venation density for a sample of extant angiosperms and fossil and living nonangiosperm tracheophytes. For most nonangiosperms, even modest increases in vein density and stomatal conductance would require substantial reconfigurations of anatomy. One characteristic of the angiosperm syndrome (e.g. small cell sizes, etc.) is hierarchical vein networks that allow expression of bundle sheath extensions in some, but not all veins, contrasting with all-or-nothing alternatives available with the single-order vein networks in most nonangiosperms. Bundle sheath modulation is associated with higher vein densities in three independent groups with hierarchical venation: angiosperms, Gnetum (gymnosperm) and Dipteris (fern). Anatomical and developmental constraints likely contribute to the stability in leaf characteristics - and ecophysiology - seen through time in different lineages and contribute to the uniqueness of angiosperms in achieving the highest vein densities, stomatal densities, and physiological rates.

Radio Interference Performance of HVAC Conductor Bundles at High-Altitude Location: Measured Data Analysis and Altitude Correction

Radio interference (RI) induced by the corona discharge of alternating current transmission lines is more severe at high altitudes than at low altitudes; hence, RI is a crucial limiting factor in the structural design of transmission lines and environmental impact assessments. To determine RI performance at high altitudes, the State Grid Corporation of China constructed an ultrahigh-voltage (UHV) corona cage in Xining in 2015 at an altitude of 2261 m. In this study, the cage was used to investigate a high number of bundled conductors under heavy rain. An RI excitation function was derived from Xining and the effects of several variables on RI performance were analyzed. In addition, RI altitude corrections were studied by comparing the Xining data with data obtained from a UHV corona cage in Wuhan located at an altitude of 23 m. The RI correction value was verified not to be a constant value but rather one that changed with the surface electric field and bundle size. The correction values obtained in this paper could enable the RI levels of high-voltage alternating current transmission lines at high altitudes to be evaluated more precisely.

Proactive Retransmission in Delay-/Disruption-Tolerant Networking for Reliable Deep-Space Vehicle Communications

Delay-/disruption-tolerant networking is recognized by the National Aeronautics and Space Administration as the only candidate network communication technology that approaches the level of maturity required for deep-space vehicle communications. Extensive performance evaluation and development of efficient data transmission mechanisms for its main protocol, bundle protocol (BP), are needed. In this paper, a new transmission approach based on “proactive” retransmission is proposed for BP for highly efficient data delivery in deep-space communications characterized by a high rate of data loss, long signal propagation delay, and highly asymmetric channel rate, given ample transmission bandwidth. The objective is to ensure successful and reliable deep-space file transfer within a single communication round-trip interval. The expected total number of transmission attempts needed for successful delivery of a file is first calculated based on the available space channel quality and the configured bundle size. Then, the time-out interval for custodial retransmission is set according to the expected number of transmission attempts required, such that all these attempts will be undertaken within the interval of a single round-trip. The performance evaluations based on both theoretical modeling and file transfer experiments indicate that the proposed proactive retransmission approach achieves the objective and has significant performance advantages over the existing reactive retransmission regardless of the transmission conditions.

Anatomía de los cladodios de Opuntia (Cactaceae) de la provincia de Buenos Aires, Argentina

Anatomía de los cladodios de Opuntia (Cactaceae) de la provincia de Buenos Aires, Argentina. El objetivo de este trabajo fue profundizar el conocimiento de la anatomía de los cladodios de nueve especies de Opuntia que crecen en la provincia de Buenos Aires, Argentina. Se hicieron preparaciones con material fresco y ejemplares de herbario siguiendo métodos habituales para microscopía óptica. Se usaron técnicas histoquímicas para identificar almidón, mucílagos y sales de oxalato. Las principales características halladas fueron: epidermis lisa y uniseriada, cutícula delgada y ceras epicuticulares; estomas grandes (entre 36-57 µm long) en baja densidad (entre 21-27/ mm2), ubicados a nivel con respecto a las restantes células epidérmicas y con una profunda cámara subestomática; hipodermis multiseriada con capa cristalífera; la corteza con clorénquima externo e hidrénquima interno. La eustela presenta haces vasculares de diferente tamaño, en algunas especies los haces mayores presentan un conducto secretor adyacente al floema. Algunas especies presentaron traqueidas con bandas de engrosamiento secundario y muy pocas tuvieron fibras en sus haces vasculares. La presencia de fibras y conducto adyacente al floema pueden ser caracteres útiles en la identificación de especies. Sin embargo, muchos aspectos requieren mayor investigación en relación con los factores ambientales, tales como la hipodermis, los cristales de oxalato de calcio y las traqueidas con bandas de engrosamiento secundario.

Dispersing Carbon Nanotubes in Water with Amphiphiles: Dispersant Adsorption, Kinetics, and Bundle Size Distribution as Defining Factors

Debundling and dispersing single-walled carbon nanotubes (SWNTs) is essential for applications, but the process is not well understood. In this work, aqueous SWNT dispersions were produced by sonicating pristine SWNT powder in the presence of an amphiphilic triblock copolymer (Pluronic F127) as dispersant. Upon centrifugation, one obtains a supernatant with suspended individual tubes and thin bundles and a precipitate with large bundles (and impurities). In the supernatant, that constitutes the final dispersion, we determined the dispersed SWNT concentration by thermogravimetric analysis (TGA) and UV–vis spectroscopy, and the dispersant concentration by 1H NMR. The fraction of dispersant adsorbed at the SWNT surface was obtained by 1H diffusion NMR. Sigmoidal dispersion curves recording the concentration of dispersed SWNTs as a function of supernatant dispersant concentration were obtained at different SWNT loadings and sonication times. As SWNT bundles are debundled into smaller and smaller ones, the ess...

Effects of Set Curvature and Fiber Bundle Size on the Printed Radius of Curvature by a Continuous Carbon Fiber Composite 3D Printer

The present study investigated the effects of set radius of curvature and fiber bundle size on the precision of the radius of curvature during continuous carbon fiber three-dimensional (3D) printing. First, individual circles with various radii using various sizes of fiber bundles were printed with a 3D printer. It was demonstrated that with a larger fiber bundle size or a smaller set radius, the printed radius would be lower than the set value. Based on the printing experiments, twist and path length difference models were constructed to predict the actual printed radius. Comparison between the models and experimental values verified that the twist model provides the upper bound on the printed radius and the path length difference model provides the lower bound.

Challenges and experiences in building an efficient apache beam runner for IBM streams

This paper describes the challenges and experiences in the development of IBM Streams runner for Apache Beam. Apache Beam is emerging as a common stream programming interface for multiple computing engines. Each participating engine implements a runner to translate Beam applications into engine-specific programs. Hence, applications written with the Beam SDK can be executed on different underlying stream computing engines, with negligible migration penalty. IBM Streams is a widely-used enterprise streaming platform. It has a rich set of connectors and toolkits for easy integration of streaming applications with other enterprise applications. It also supports a broad range of programming language interfaces, including Java, C++, Python, Stream Processing Language (SPL) and Apache Beam. This paper focuses on our solutions to efficiently support the Beam programming abstractions in IBM Streams runner. Beam organizes data into discrete event time windows. This design, on the one hand, supports out-of-order data arrivals, but on the other hand, forces runners to maintain more states, which leads to higher space and computation overhead. IBM Streams runner mitigates this problem by efficiently indexing inter-dependent states, garbage-collecting stale keys, and enforcing bundle sizes. We also share performance concerns in Beam that could potentially impact applications. Evaluations show that IBM Streams runner outperforms Flink runner and Spark runner in most scenarios when running the Beam NEXMark benchmarks. IBM Streams runner is available for download from IBM Cloud Streaming Analytics service console.

Coarse-Grained Molecular Dynamics Study of Ionomer Aggregation and Network Formation in Dilute Solution

The presented work comprises a computational study of self-assembly in dilute solution of Nafion-type perfluorosulfonic acid (PFSA) ionomers. We employ coarse-grained molecular dynamics (CGMD) to investigate the formation of ionomer bundles [1] and study the assembly of ionomer bundles into a bundle network upon increasing ionomer concentration. Formation of this supramolecular network is experimentally indicated by a markedly increased viscosity [2]. Evolution of a gel-like structure in the aqueous solutions also studied experimentally by Cirkel et al. [3] and Rubatat et al. [4], revealing more details about transport properties, stability, and water sorption properties of the network structure of interconnected ionomer bundles in Nafion membranes. Simulation of the interconnected, gel-like ionomer state provides opportunities to scrutinize different proposed structural models of ionomer membranes and assess changes in bundle size and network connectivity as functions of backbone hydrophobicity, side chain density, counterion valence, and strength of electrostatic interaction between anionic head groups at ionomer sidechains.

Morphological Characteristics of Bambusa vulgaris and the Distribution and Shape of Vascular Bundles therein

Bamboo culm comprises internodes and nodes and is tapered from the bottom to the top. Anatomically, bamboo culm comprises vascular bundles and parenchymal base tissue. The gross anatomical structure of a transverse section of any culm internode is determined by the shape, size, arrangement, and number of vascular bundles. The purpose of this research was to examine the morphology of culm and the distribution and shape of vascular bundles in Ampel bamboo (Bambusa vulgaris). Bamboo culms were harvested from the base. Test samples were obtained from a central 2-cm long segment of each internode across the entire length of the culm. Results showed an uneven spread of vascular bundles in the internode cross-section. Transitioning from the outer to the inner layer of the internode, the number of vascular bundles per unit area decreased and their shape was variable. The size of vascular bundles in the middle layer of the internode was greater than that of those in the outer and inner layers. The shape of vascular bundles was circular in the outer layer, which gradually transformed into vertical oval toward the middle layer and horizontal oval toward the inner layer. Vascular bundles were of type III and IV in the bottom of the culm and type III in the middle to the top of the culm.

Quantitative study of bundle size effect on thermal conductivity of single-walled carbon nanotubes

Compared with isolated single-walled carbon nanotubes (SWNTs), thermal conductivity is greatly impeded in SWNT bundles; however, the measurement of the bundle size effect is difficult. In this study, the number of SWNTs in a bundle was determined based on the transferred horizontally aligned SWNTs on a suspended micro-thermometer to quantitatively study the effect of the bundle size on thermal conductivity. Increasing the bundle size significantly degraded the thermal conductivity. For isolated SWNTs, thermal conductivity was approximately 5000 ± 1000 W m–1 K–1 at room temperature, three times larger than that of the four-SWNT bundle. The logarithmical deterioration of thermal conductivity resulting from the increased bundle size can be attributed to the increased scattering rate with neighboring SWNTs based on the kinetic theory.

Thermal properties of freezing bound water restrained by sodium lignosulfonate-based polyurethane hydrogels

In order to develop a new functional product from lignin, sodium lignosulfonate (LS)-based polyurethane (LSPU) hydrogels were prepared from LS and hexamethylene diisocyanate (HDI) derivatives in water. Isocyanate/hydroxyl group ratio (NCO/OH ratio) was varied from 0.05 to 0.8 mol mol−1, and water content (Wc = mass of water/mass of dry sample) of the obtained LSPU hydrogels was varied from 0 to 3.0 g g−1. Phase transition behavior of hydrogels with various Wc’s was investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). In DSC heating curve of LSPU hydrogels, glass transition, cold crystallization, melting and liquid crystallization were observed. Cold crystallization, two melting peaks and variation of melting enthalpy indicate that three kinds of water, i.e., non-freezing water, freezing bound water and free water, exist in LSPU hydrogel. Glass transition temperature (Tg) decreased from 230 to 190 K in a Wc range where non-freezing water was formed in the hydrogel. Tg increased when freezing bound water was formed in the system. Tg leveled off in a Wc range where normal ice was formed. The effect of NCO/OH ratio on molecular motion of LSPU hydrogel is examined based on Tg and heat capacity difference at Tg (ΔCp). Water vaporization curve measured by TG also indicates the presence of bound water which evaporates at a temperature higher than ca. 410 K. By atomic force microscopic observation, the size of molecular bundle of LSPU hydrogel is calculated and compared with that of LS-water system. By cross-linking, the height of molecular bundle decreased from ca. 3–1 nm and lignin molecules extend in a flat structure.

Throughput time analysis in apparel manufacturing

Throughput time is investigated for men’s shirt assembly line in garment manufacturing company. The comparison is made between theoretically calculated and actual throughput time. The theoretical throughput time is calculated via starting lag times, lag times and bundle times between succeeding pairs of operations of the product flow process grid critical path. The influence of bundle size on throughput time and work in process is evaluated. The comparison of predicted and actual throughput time shows that predicted time was 10% lesser than experimental one. The evaluation of bundle size effect on throughout time and work in process shows that the bundle size can have great influence on company flexibility and competiveness.

Markov decision‐based optimisation on bundle size for satellite disruption/delay‐tolerant network links

In a satellite disruption/delay-tolerant network, bundle delivery is obviously affected by time-varying parameters, i.e. bit error rate and propagation latency, due to constantly changing distance and connectivity between paired orbital nodes. The authors proposed a Markov decision-based optimisation approach for bundle size, which could efficiently improve the expected time of delivery over a dynamic two-hop inter-satellite link. In particular, a group of optimal bundle sizes are adaptively selected according to current distance-dependent channel parameters, leading to a full utilisation on intermediate node's memory. The simulation results verified the proposed method under different conditions with comparison.

Vegetative anatomy of the orchid Bulbophyllum sterile (Orchidaceae: Epidendroideae)

The anatomical characteristics of leaf, pseudobulb, and root of Bulbophyllum sterile of the subfamily Epidendroideae (Orchidaceae) were investigated. The anatomical investigation involved observing sections after staining with different stains as well as scanning electron microscopy. Additionally, the cell dimensions were also measured. The amphistomatic leaves of B. sterile had a thick cuticle, paracytic type of stomata, collateral vascular bundles and starch grains. The rhizome had cuticularized uniseriate epidermis and a single layer of the hypodermis. The parenchymatous stem ground tissue was distinguished into outer and inner regions separated by a band of sclerenchymatous tissue. Collateral vascular bundles were distributed in the inner ground tissue. The size of the vascular bundles generally increased from the periphery towards the center. A sclerenchymatous patch covered the phloem pole, whereas the xylem is covered by thin walled parenchymatous cells. The outer surface of the pseudobulb is covered by a thick cuticle. The parenchymatous ground tissue consisted of starch grains, aeration, water and algal cells and scattered collateral vascular bundles. Sclerenchymatous cells covered the phloem pole, whereas the xylem is covered by thin-walled cells. The velamen in B. sterile is single layered consisting of highly elongated compactly arranged cells. Uniseriate exodermis is dimorphic consisting of long and short cells. Cortical cells are differentiated into exodermis and endodermis. The O-thickened endodermal cell layer is interrupted by thin walled passage cells. Pith is sclerenchymatous. From this study, it can be concluded that B. sterile possess anatomical adaptations to xeric conditions in all the vegetative organs.

Morphometrics of the Southern Green Stink Bug [Nezara viridula (L.) (Hemiptera: Pentatomidae)] Stylet Bundle.

The southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), is a cosmopolitan pest of high-value cash crops, including cotton (Gossypium hirsutum L.; Malvales: Malvaceae). The pest can ingest and transmit disease-causing bacterial and fungal pathogens of cotton. We hypothesized that the size of the food canal may contribute to selective transmission, as observed in previous reports. The objective of this study was to examine food canal size and other morphometric parameters of the southern green stink bug stylet bundle at two locations (labium and head) to improve our understanding of factors that may contribute to pathogen transmission. For the food canal, females possessed significantly larger canals than males, major axes were significantly longer than minor axes, and canal sizes were numerically higher at the labium compared with the head. For salivary canal, mean axes lengths were similar between sexes and the head and labium. For both food and salivary canals, axes lengths were longer and area was larger at the labium compared with the head. These findings indicate the presence of a "funnel effect" with canals becoming narrower proximally. Sex and location significantly affected the size of the intact stylet bundle. Results indicate the food canal size was not a factor affecting previously observed selective passive transmission. Major and minor axes measurements, coupled with morphological observations of canal shapes and observed "funnel effect" in the food and salivary canals, improve our understanding of the hemipteran stylet bundle and its relationship with the insect's internal morphology.

Mesoscopic modeling of the uniaxial compression and recovery of vertically aligned carbon nanotube forests

Vertically aligned carbon nanotube (VACNT) arrays or “forests” represent a promising class of mechanically strong and resilient lightweight materials, capable of supporting large reversible deformation and absorbing mechanical energy. The mechanical response of VACNT forests to uniaxial compression is defined by various factors, including the material microstructure, its density, height, rate of deformation, and the nature of interaction between carbon nanotubes (CNTs) and the compressing indenter. In this paper, we use a coarse-grained mesoscopic model to simulate the uniaxial compression of VACNT samples with different densities and microstructures (bundle size distribution and degree of nanotube alignment) to obtain a clear microscopic picture of the structural changes in networks of interconnected CNT bundles undergoing mechanical deformation. The key factors responsible for the coordinated buckling of CNTs, reversible and irreversible modes of deformation in VACNT arrays undergoing uniaxial compression, as well as hysteresis behavior in VACNT arrays subjected to five loading–unloading cycles are investigated in the simulations. The simulation results reveal the important role of the collective buckling of CNTs across bundle cross-sections as well as a complex deformation behavior of VACNT arrays defined by an interplay of different modes of bundle deformation. The loading rate and the CNT attachment to the indenter are found to have a strong effect on the deformation mechanisms and the overall mechanical behavior of VACNT forests. A good agreement with experimental data from in situ mechanical tests is observed for the general trends and magnitudes of loss coefficients predicted in the simulations. The forest morphology can strongly alter the mechanical behavior of VACNT arrays with nominally the same general characteristics, such as CNT radius, length, and material density, thus suggesting the opportunity for substantial enhancement of the mechanical properties through the microstructure modification.