Junction Density Research Articles

On the computation of the energy-optimal route dependent on the traffic load in Ingolstadt

In this paper, we evaluate energy-optimal paths in the road network of Ingolstadt. The energy consumptions associated with the segments of the road network are derived from the measurements of the traffic load based on vehicle probe data, using a mesoscopic traffic model and a physical vehicle consumption model. The resulting description of the network is time-dependent, thereby reproducing the variations in time of the traffic load in Ingolstadt. The results suggest that the average energy consumption associated with energy-optimal paths is approximately 10% lower than the average energy consumption associated with fast paths. Moreover, we find that energy-optimal paths differ from fast paths in more than 90% of the considered test cases and that the density of junctions has a strong impact on the average energy consumptions. Although the time dependency of the network description leads to an increase in the computation time of optimal paths, the query times of one of the evaluated methods are promising for practical applications.

Density-controllable growth of SnO2 nanowire junction-bridging across electrode for low-temperature NO2 gas detection

The junction-bridging structure of metal oxide nanowires (NWs) improves gas-sensing properties. In this study, an on-chip growth method was used to fabricate gas sensors, it easily and effectively controls NW junctions. SnO2 NWs were synthesized by thermal evaporation at 800 °C with tin powder as the source. The density of the NW junctions was controlled by changing the mass of the source material. A source material with large mass yielded high-density NW junctions. With electrode spacing of 20 μm, NW junctions were formed from the source material of larger than 2 mg. Gas sensing results revealed that the junction sensors exhibited a good response to NO2 gas at a concentration of 1–10 ppm. The sensors exhibited a good response to NO2 gas at low temperature of up to 100 °C and short response–recovery time (~20 s). The sensors also had good selectivity to NO2 gas. The response (R gas /R air) to 1 ppm NO2 was as high as 22 at 100 °C, whereas the cross gas responses (R air /R gas) to 10 ppm CO, 10 ppm H2S, 100 ppm C2H5OH, and 100 ppm NH3 were negligible (1.1–1.3).

Increased Epithelial Permeability Is the Primary Cause for Bicarbonate Loss in Inflamed Murine Colon

Bicarbonate loss into the lumen occurs during intestinal inflammation in different species. However, candidate pathways like CFTR or DRA are inhibited in the inflamed gut. This study addressed the question whether and how inflammation-associated increased intestinal permeability may result in epithelial HCO(3)(-) loss. Murine proximal colon was studied because it does not express functional DRA but is inflamed in the tumor necrosis factor α overexpressing mouse model (TNF(ΔARE)). Luminal alkalization, (3)H-mannitol fluxes, impedance spectroscopy, and dilution potentials were measured in Ussing chambers, whereas expression and localization of tight junction-associated proteins were analyzed by Western blots and immunohistochemistry. Luminal alkalization rates and (3)H-mannitol fluxes were increased in TNF(+/ΔARE) proximal colon, whereas forskolin-stimulated I(sc) was not altered. Epithelial resistance was reduced, but subepithelial resistance increased. The epithelial lining was intact, and enterocyte apoptosis rate was not increased despite massively increased Th1 cytokine levels and lymphoplasmacellular infiltration. Measurement of dilution potentials suggested a loss of cation selectivity with increased anion permeability. Western analysis revealed a downregulation of occludin expression and an upregulation of both claudin-2 and claudin-5, with no change in ZO-1, E-cadherin, claudin-4, and claudin-8. Immunohistochemistry suggested correct occludin localization but reduced tight junction density in TNF(+/ΔARE) surface epithelium. Inflammation during TNF-α overexpression leads to increased epithelial permeability in murine proximal colon, decreased tight junctional cation selectivity, and increased HCO(3)(-) loss into the lumen. Inflammation-associated colonic HCO(3)(-) loss may occur through leaky tight junctions rather than through HCO(3)(-) secreting ion transporters.

A stochastic algorithm for modeling heat welded random carbon nanotube network

Carbon nanotubes (CNTs) are one of the presents of nanotechnology being investigated due to their extraordinary mechanical, thermal and electrical properties. Carbon nanotube networks feed the idea that CNTs can be used as the building blocks of new advanced materials utilizing the superior characteristics of CNTs. In this way, nanoscale features of CNTs can be scaled up to even continuum proportions. In this study, 2-D and 3-D CNT network generation methods are introduced by which the geometrical parameters, such as CNT length, chirality, intersection angle and junctional density, can be controlled and a random CNT network is obtained. Then, molecular dynamics (MD) simulations are used to create covalent bonds between intersecting CNTs, which allow the investigation of the mechanical, thermal and electrical properties of random CNT networks.

Aligned Carbon Nanotubes for High‐Efficiency Schottky Solar Cells

The development of low-cost and high-efficiency silicon Schottky solar cells has drawn considerable interest in recent years. A facial approach for the fabrication of carbon nanotube-silicon (CNT-Si) Schottky solar cells by using aligned double-walled CNTs drawn from a CNT array is demonstrated. The aligned CNTs help to form high CNT-Si junction density and provide efficient charge-transport paths. The power conversion efficiency (PCE) reaches 10.5%, which is higher than that of solar cells fabricated using pristine and random CNT networks. Furthermore, the cell fabrication is scalable, and the solar cells fabricated in one batch show very small PCE fluctuations.

Nanostructure and surface effects on yield in Cu nanowires

The yield strengths of nanomaterials are highly sensitive to their internal and surface structures. However, it is difficult to identify a priori which structural feature will govern plastic yield. We employ very large scale molecular dynamics simulations to explicitly identify the relevant yield mechanisms for Cu nanowires with four distinct, experimentally realizable nanostructures: single crystal (SC), nanotwinned single crystal (NTSC), nanocrystal (NC) and nanotwinned nanocrystal (NTNC). By characterizing the deformation at the yield point on the atomic scale, our simulations elucidate the effects of surface defects, nanotwins and grain boundaries on the commencement of yield and reveal several critically important features of the yielding process. First, the initial yields in all nanowires occur via dislocation nucleation at different characteristic nanostructural features. SC and NTSC nanowires yield via dislocation nucleation from surfaces or surface defects, while NC and NTNC nanowires yield via dislocation nucleation from grain boundary triple junctions. Second, our simulations highlight the relative potency of stress concentrators arising from different imperfections in modulating the yield strength of nanowires. Grain boundary triple junctions are as effective as surface defects at acting as stress concentrators. However, the higher density of triple junctions in NC and NTNC nanowires renders these structures considerably weaker than their SC and NTSC counterparts. Third, the presence of nanotwins only marginally enhances the yield strength of nanocrystalline Cu nanowires, which is in line with experimental observation in NTNC Cu nanowires but contrary to that in bulk ultrafine-grain nanotwinned Cu. The reason for this divergent behavior is that in nanowires yield strength is governed by dislocation nucleation from triple junctions in contrast to dislocation propagation in the bulk. Finally, excellent agreement is obtained between the relative yield strengths, stress–strain behavior and dislocation nucleation conditions of nanowires in our simulations and existing experimental data. This suggests that our predicted atomistic processes controlling yield in our simulations may also control yield in experiments.

Off Label Use of Botulinum Toxin in Children under Two Years of Age: A Systematic Review

The treatment of children with cerebral palsy with Botulinum Toxin is considered safe and effective, but is only approved for children older than two years of age. The effect of BoNT-A injection on juvenile skeletal muscle especially on neuromuscular junction density, distribution and morphology is poorly delineated and concerns of irreversible damage to the motor endplates especially in young children exist. In contrast, earlier treatment could be appropriate to improve the attainment of motor milestones and general motor development. This review systematically analyzes the evidence regarding this hypothesis. A database search, including PubMed and Medline databases, was performed and all randomized controlled trials (RCTs) comparing the efficacy of Botulinum Toxin in children younger than two years were identified. Two authors independently extracted the data and the methods of all identified trials were assessed. Three RCTs met the inclusion criteria. The results of the analysis revealed an improvement in spasticity of the upper and lower extremities as well as in the range of motion in the joints of the lower limbs. However, evidence of an improvement of general motor development could not be found, as the assessment of this area was not completely specified for this patient group. Based on available evidence it can not be concluded that Botulinum Toxin treatment in children younger than two years improves the achievement of motor milestones. However, there is evidence for the reduction of spasticity, avoiding contractures and delaying surgery. Due to some limitations, the results of this review should be cautiously interpreted. More studies, long-term follow up independent high-quality RCTs with effectiveness analyses are needed.

Twinning in Strained Ferroelastics: Microstructure and Statistics

The generation of functional interfaces such as superconducting and ferroelectric twin boundaries requires new ways to nucleate as many interfaces as possible in bulk materials and thin films. Materials with high densities of twin boundaries are often ferroelastics and martensites. In this review, we show that the nucleation and propagation of twin boundaries depend sensitively on temperature and system size. Sudden changes of the domain pattern manifest themselves as avalanches or “jerks” in the potential energy of the sample. At high temperatures, the change of the twin pattern is thermally activated; the probability P to find sudden energy changes of jerks E follows the Vogel–Fulcher statistics P(E) ~ exp (E/(T − T VF)), whereas the athermal regime at low temperatures corresponds to power-law statistics P(E) ~ E −e . We find that the complexity of the pattern is well characterized by the number of junctions between twin boundaries. Materials with soft bulk moduli have much higher junction densities than those with hard bulk moduli. Soft materials also show an increase in the junction density with diminishing sample size. The change of the complexity and the number density of twin boundaries represents an important step forward in the development of “domain boundary engineering,” where the functionality of the materials is directly linked to the domain pattern.

Betavoltaic Battery Conversion Efficiency Improvement Based on Interlayer Structures

Significant differences among the doping densities of PN junctions in semiconductors cause lattice mismatch and lattice defects that increase the recombination current of betavoltaic batteries. This extensively decreases the open circuit voltage and the short current, which results in low conversion efficiency. This study proposes P+PINN+-structure based betavoltaic batteries by adding an interlayer to typical PIN structures to improve conversion efficiency. Numerical simulations are conducted for the energy deposition of beta particles along the thickness direction in semiconductors. Based on this, 63Ni-radiation GaAs batteries with PIN and P+PINN+ structures are designed and fabricated to experimentally verify the proposed design. It turns out that the conversion efficiency of the betavoltaic battery with the proposed P+PINN+ structure is about 1.45 times higher than that with the traditional PIN structure.

Fabrication and properties of trench-structured networked SnO2 nanowire gas sensors

On the basis of on-chip trench structure, multiple-networked SnO2 nanowire sensors are successfully fabricated by the use of the selective growth of SnO2 nanowires and their entanglement nature. The sensing performance of the trench-structured SnO2 nanowire sensors is investigated in terms of NO2. The density of nanowire junctions is deliberately controlled via changing either the trench width or the time of nanowire growth. A model is proposed to provide a general rule for preparing trench-structured nanowire sensors of superior sensing performance.

Enhanced sensitivity of aged fibrotic hearts to angiotensin II- and hypokalemia-induced early afterdepolarization-mediated ventricular arrhythmias

Unlike young hearts, aged hearts are highly susceptible to early afterdepolarization (EAD)-mediated ventricular fibrillation (VF). This differential may result from age-related structural remodeling (fibrosis) or electrical remodeling of ventricular myocytes or both. We used optical mapping and microelectrode recordings in Langendorff-perfused hearts and patch-clamp recordings in isolated ventricular myocytes from aged (24-26 mo) and young (3-4 mo) rats to assess susceptibility to EADs and VF during either oxidative stress with ANG II (2 μM) or ionic stress with hypokalemia (2.7 mM). ANG II caused EAD-mediated VF in 16 of 19 aged hearts (83%) after 32 ± 7 min but in 0 of 9 young hearts (0%). ANG II-mediated VF was suppressed with KN-93 (Ca(2+)/calmodulin-dependent kinase inhibitor) and the reducing agent N-acetylcysteine. Hypokalemia caused EAD-mediated VF in 11 of 11 aged hearts (100%) after 7.4 ± 0.4 min. In 14 young hearts, however, VF did not occur in 6 hearts (43%) or was delayed in onset (31 ± 22 min, P < 0.05) in 8 hearts (57%). In patch-clamped myocytes, ANG II and hypokalemia (n = 6) induced EADs and triggered activity in both age groups (P = not significant) at a cycle length of >0.5 s. When myocytes of either age group were coupled to a virtual fibroblast using the dynamic patch-clamp technique, EADs arose in both groups at a cycle length of <0.5 s. Aged ventricles had significantly greater fibrosis and reduced connexin43 gap junction density compared with young hearts. The lack of differential age-related sensitivity at the single cell level in EAD susceptibility indicates that increased ventricular fibrosis in the aged heart plays a key role in increasing vulnerability to VF induced by oxidative and ionic stress.

Extraocular muscles in patients with infantile nystagmus: adaptations at the effector level.

To test the hypothesis that the extraocular muscles (EOMs) of patients with infantile nystagmus have muscular and innervational adaptations that may have a role in the involuntary oscillations of the eyes. Specimens of EOMs from 10 patients with infantile nystagmus and postmortem specimens from 10 control subjects were prepared for histologic examination. The following variables were quantified: mean myofiber cross-sectional area, myofiber central nucleation, myelinated nerve density, nerve fiber density, and neuromuscular junction density. In contrast to control EOMs, infantile nystagmus EOMs had significantly more centrally nucleated myofibers, consistent with cycles of degeneration and regeneration. The EOMs of patients with nystagmus also had a greater degree of heterogeneity in myofiber size than did those of controls, with no difference in mean myofiber cross-sectional area. Mean myelinated nerve density, nerve fiber density, and neuromuscular junction density were also significantly decreased in infantile nystagmus EOMs. The EOMs of patients with infantile nystagmus displayed a distinct hypoinnervated phenotype. This represents the first quantification of changes in central nucleation and myofiber size heterogeneity, as well as decreased myelinated nerve, nerve fiber, and neuromuscular junction density. These results suggest that deficits in motor innervation are a potential basis for the primary loss of motor control. Improved understanding of the etiology of nystagmus may direct future diagnostic and treatment strategies.

Subthreshold somatic voltage in neocortical pyramidal cells can control whether spikes propagate from the axonal plexus to axon terminals: a model study

There is suggestive evidence that pyramidal cell axons in neocortex may be coupled by gap junctions into an "axonal plexus" capable of generating very fast oscillations (VFOs) with frequencies exceeding 80 Hz. It is not obvious, however, how a pyramidal cell in such a network could control its output when action potentials are free to propagate from the axons of other pyramidal cells into its own axon. We address this problem by means of simulations based on three-dimensional reconstructions of pyramidal cells from rat somatosensory cortex. We show that somatic depolarization enables propagation via gap junctions into the initial segment and main axon, while somatic hyperpolarization disables it. We show further that somatic voltage cannot effectively control action potential propagation through gap junctions on minor collaterals; action potentials may therefore propagate freely from such collaterals regardless of somatic voltage. In previous work, VFOs are all but abolished during the hyperpolarization phase of slow oscillations induced by anesthesia in vivo. This finding constrains the density of gap junctions on collaterals in our model and suggests that axonal sprouting due to cortical lesions may result in abnormally high gap junction density on collaterals, leading in turn to excessive VFO activity and hence to epilepsy via kindling.

Nine-month results of intravitreal bevacizumab versus triamcinolone for the treatment of diffuse diabetic macular oedema: a retrospective analysis

To compare efficacy of intravitreal bevacizumab versus triamcinolone in the treatment of diffuse diabetic macular oedema (DME). This retrospective nonrandomized study includes 60 patients with diffuse DME treated with at least one intravitreal triamcinolone injection (ITA) or intravitreal bevacizumab injection (IBe). Regression analysis was performed for pretreatment, glycosylated haemoglobin level, visual acuity (VA) at baseline and central macular thickness (CMT) at baseline. After 1-, 3-, 6- and 9-month follow-up, there was no significant change in either VA or CMT treatment in the ITA and IBe groups. There was no statistically significant difference between the two treatment groups. Changes in CMT and VA in the subgroups were not significant. Only predictive factor independent of HbA1c level and VA was CMT at baseline in both treatment groups. The thicker CMT at baseline, the higher was reduction in CMT. After 1 month, the IBe group had a significantly higher decrement than the ITA group. In our study collective, neither IBe nor ITA treatment was able to improve VA during follow-up, significantly. CMT was reduced in both treatment groups, however not significantly. Our data demonstrates that reduction in CMT with either IBe or ITA treatment was significantly influenced by degree of CMT at baseline.

Photovoltaic Response of Carbon Nanotube-Silicon Heterojunctions: Effect of Nanotube Film Thickness and Number of Walls

We report on the multiwall carbon nanotube application as energy conversion material to fabricate thin film solar cells, with nanotubes acting as photogeneration sites as well as charge separators, collectors and carrier transporters. The device consists of a semitransparent thin film of nanotubes coating a n-type crystalline silicon substrate. Under illumination electron-hole (e-h) pairs, generated in the nanotubes and in the silicon substrate underneath, are split and charges are transported through the nanotubes (electrons) and the n-Si (holes). We found that a suitable thickness of the nanotube thin film, high density of Schottky junctions between nanotubes and n-Si and lowest number of nanotube walls are all fundamental parameters to improve the device incident photon to electron conversion efficiency. Multiwall carbon nanotubes have been synthesized by chemical vapour deposition in an ultra high vacuum chamber by evaporating a given amount of iron at room temperature and then exposing the substrate kept at 800 degrees C at acetylene gas. The amount of deposited iron is found to directly affect the nanotube size distribution (inner and outer diameter) and therefore the number of walls of the nanotubes.

Performance of the MRI-based virtual bone biopsy in the distal radius: Serial reproducibility and reliability of structural and mechanical parameters in women representative of osteoporosis study populations

Serial reproducibility and reliability critically determine sensitivity to detect changes in response to intervention and provide a basis for sample size estimates. Here, we evaluated the performance of the MRI-based virtual bone biopsy in terms of 26 structural and mechanical parameters in the distal radius of 20 women in the age range of 50 to 75 years (mean=62.0 years, S.D.=8.1 years), representative of typical study populations in drug intervention trials and fracture studies. Subjects were examined three times at average intervals of 20.2 days (S.D.=14.5 days) by MRI at 1.5 T field strength at a voxel size of 137×137×410 μm(3). Methods involved prospective and retrospective 3D image registration and auto-focus motion correction. Analyses were performed from a central 5×5×5 mm(3) cuboid subvolume and trabecular volume consisting of a 13 mm axial slab encompassing the entire medullary cavity. Whole-volume axial stiffness and sub-regional Young's and shear moduli were computed by finite-element analysis. Whole-volume-derived aggregate mean coefficient of variation of all structural parameters was 4.4% (range 1.8% to 7.7%) and 4.0% for axial stiffness; corresponding data in the subvolume were 6.5% (range 1.6% to 13.0%) for structural, and 5.5% (range 4.6% to 6.5%) for mechanical parameters. Aggregate ICC was 0.976 (range 0.947 to 0.986) and 0.992 for whole-volume-derived structural parameters and axial stiffness, and 0.946 (range 0.752 to 0.991) and 0.974 (range 0.965 to 0.978) for subvolume-derived structural and mechanical parameters, respectively. The strongest predictors of whole-volume axial stiffness were BV/TV, junction density, skeleton density and Tb.N (R(2) 0.79-0.87). The same parameters were also highly predictive of sub-regional axial modulus (R(2) 0.88-0.91). The data suggest that the method is suited for longitudinal assessment of the response to therapy. The underlying technology is portable and should be compatible with all general-purpose MRI scanners, which is appealing considering the very large installed base of this modality.

Recovery by triple junction motion in aluminium deformed to ultrahigh strains

Commercial purity aluminium at true strains ε =2∼5.5 was annealed in a wide temperature range (from room temperature to 220°C), and the evolution of microstructure was characterized using transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) techniques. Triple junctions in an ultrafine lamellar structure are classified into three categories based on the structural morphology, and a relationship is formulated between the density (length per unit volume) of triple junctions and the boundary spacing. The triple junction density increases with increasing strain during plastic deformation and decreases during isochronal and isothermal annealing. Based on TEM and EBSD observations, thermally activated triple junction motion is identified as the key process during the recovery of highly strained aluminium, leading to the removal of thin lamellae with small dihedral angles at the ends and structural coarsening. A mechanism for recovery by triple junction motion is proposed, which can underpin the general observation that a lamellar structure formed by plastic deformation during annealing can evolve into an equiaxed structure, preceding further structural coarsening and recrystallization. Within this framework, the grain boundary surface tension on triple junctions is discussed based on the structural parameters characterizing the deformed and annealed microstructure.

Junction-Tuned SnO2 Nanowires and Their Sensing Properties

On the basis of a selective growth of SnO2 nanowires by the vapor–liquid–solid growth method, networked SnO2 nanowire sensors were fabricated. Then, their sensing properties were systematically investigated in terms of NO2. The density of junctions was controlled by altering the spacing of the patterned-interdigital electrodes (PIEs), on which SnO2 nanowires selectively grew and touched the nanowires grown on neighboring PIEs, eventually producing junctions. The sensing mechanism was attributed to the change not only in the width of the space charge region along the length direction of each nanowire but also in the height of the built-in potential at the junctions during adsorption and desorption of gaseous species. Narrower spacings of PIEs led to an increasing the density of junctions projected to the plane and, consequently, superior properties for gas sensing. Importantly, a general principle to prepare networked nanowires of superior sensing capabilities was suggested from the point of view of nanowire shape and electrode configuration.

Practical Operation of Cryogen-Free Programmable Josephson Voltage Standards

Cryogen-free operation is rapidly becoming the preferred implementation of most superconducting electronics systems including programmable Josephson voltage standard (PJVS) systems. There are strong operational incentives for using the smallest possible cryocooler in order to minimize acoustic noise, system footprint, and power consumption. In addition, Nb/NbxSi1-x/Nb junction technology, which operates near 4 K, offers better yield than NbN/TiNx/NbN technology, which can operate at 8.5 K, thus making lower temperature operation near 4 K desirable. As junction density increases, however, self-heating of the junctions can create significant thermal gradients between the arrays and coldhead. Thus careful design of the overall system is required to maintain acceptable operating margins. We have developed a calorimetric measurement technique to characterize the system variables and used it to evaluate several different PJVS configurations. This technique uses the PJVS subarrays as both heat sources and temperature sensors, in conjunction with a time gated measurement technique, to characterize the thermal response of the system. A passive thermal filter incorporating a Pb thermal mass is used to reduce the temperature oscillations of the cryocooler. Our results suggest that, with appropriate system design, operation of a practical 10 V PJVS on a small (nominally 100 mW capacity at 4.2 K) cryocooler may be possible.

Modulating Neuromuscular Junction Density Changes in Botulinum Toxin–Treated Orbicularis Oculi Muscle

Botulinum toxin A is the most commonly used treatment for blepharospasm, hemifacial spasm, and other focal dystonias. Its main drawback is its relatively short duration of effect. The goal of this study was to examine the ability of corticotropin releasing factor (CRF) or antibody to insulin growth factor I-receptor (anti-IGFIR) to reduce the up-regulation of neuromuscular junctions that are associated with return of muscle function after botulinum toxin treatment. Eyelids of adult rabbits were locally injected with either botulinum toxin alone or botulinum toxin treatment followed by injection of either CRF or anti-IGFIR. After one, two, or four weeks, the orbicularis oculi muscles within the treated eyelids were examined for density of neuromuscular junctions histologically. Injection of botulinum toxin into rabbit eyelids resulted in a significant increase in the density of neuromuscular junctions at one and two weeks, and an even greater increase in neuromuscular junction density by four weeks after treatment. Treatment with either CRF or anti-IGFIR completely prevented this increase in neuromuscular junction density. The return of function after botulinum toxin-induced muscle paralysis is due to terminal sprouting and formation of new neuromuscular junctions within the paralyzed muscles. Injection with CRF or anti-IGFIR after botulinum toxin treatment prevents this sprouting, which in turn should increase the duration of effectiveness of single botulinum toxin treatments. Future physiology studies will address this. Prolonging botulinum toxin's clinical efficacy should decrease the number of injections needed for patient muscle spasm relief, decreasing the risk of negative side effects and changes in drug effectiveness that often occurs over a lifetime of botulinum toxin exposure.