Strand Diameter Research Articles

Detection of short single-strand DNA homopolymers with ultrathin Si3N4 nanopores.

A series of nanopores with diameters ranging from 2.5 to 63 nm are fabricated on a reduced Si3N4 membrane by focused ion beam and high energy electron beam. Through measuring the blocked ionic currents for DNA strands threading linearly through those solid-state nanopores, it is found that the blockade ionic current is proportional to the square of the hydrodynamic diameter of the DNA strand. With the nanopore diameter reduced to be comparable with that of DNA strands, the hydrodynamic diameter of the DNA becomes smaller, which is attributed to the size confinement effects. The duration time for the linear DNA translocation events increases monotonically with the nanopore length. By comparing the spatial configurations of DNA strands through nanopores with different diameters, it is found that the nanopore with large diameter has enough space to allow the DNA strand to translocate through with complex conformation. With the decrease of the nanopore diameter, the folded part of the DNA is prone to be straightened by the nanopore, which leads to the increase in the occurrence frequency of the linear DNA translocation events. Reducing the diameter of the nanopore to 2.5 nm allows the detection and discrimination of three nucleotide "G" and three nucleotide "T" homopolymer DNA strands based on differences in their physical dimensions.

Reduced Magnetization and Loss in Ag–Mg Sheathed Bi2212 Wires: Systematics With Sample Twist Pitch and Length

Suppression of magnetization and effective filament diameter deff with twisting was investigated for a series of recent Bi2212 strands manufactured by Oxford Superconducting Technologies. We measured magnetization as a function of field (out to 14 T), at 5.1 K, of twisted and nontwisted 37 × 18 double restack design strands. The samples were helical coils 5-6 mm in height and approximately 5 mm in diameter. The strand diameter was 0.8 mm. The magnetization of samples having twist pitches of 25.4, 12.7, and 6.35 mm were examined and compared to nontwisted samples of the same filament configuration. The critical state model was used to extract the 12-T d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> from magnetization data for comparison. Twisting the samples reduced d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> by a factor of 1.5-3. The d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> was shown to increase both with L and L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> . Mathematical expressions, based upon the anisotropic continuum model, were fit to the data, and a parameter γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , which quantifies the electrical connectivity perpendicular to the filament axis, was extracted. The bundle-to-bundle connectivity along the radial axis was found to be approximately 0.2%. The d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> was substantially reduced with L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> . In addition, the importance of understanding sample length dependence for quantitative measurements is discussed.

Verification Testing of ITER Nb&lt;sub&gt;3&lt;/sub&gt;Sn Strand at the NHMFL

The large quantity of Nb 3 Sn superconducting wire needed by ITER presents a significant challenge to ensure that all wires adhere to ITER specifications. The National High Magnetic Field Laboratory, USA performed verification tests for Nb 3 Sn strands used in ITER TF magnets. Converting a research laboratory into a large quantity testing facility presented many challenges in developing standard operating procedures for all the verification tests. Verification tests required by ITER include: unreacted-chrome-plated strand diameter, twist pitch and twist direction, chrome-plating thickness, unreacted-chrome-plated strand Cu-to-non-Cu volume ratio, residual resistivity ratio of Cr-plated strand (RRR), critical current at 4.22 K and 12 T (I c ), resistive transition index at 4.22 K and 12 T (n-value), and hysteresis loss per strand unit volume at 4.22 K over a ±3 T cycle. Additionally, due to the brittle nature of Nb 3 Sn superconducting wire, some samples were damaged in a controlled manner to explore the negative extremes of damage due to sample handling. We successfully completed the verification tests of ITER TF Nb 3 Sn strands made by US vendors.

Analytical optimization of litz-wire windings independent of porosity factor

Purpose – The purpose of this paper is threefold. First, an analytical model based on one-dimensional Dowell’s equation for computing ac-to-dc winding resistance ratio FR of litz wire is presented. The model takes into account proximity effect within the bundle and between bundle layers as well as the skin effect. Second, low- and medium-frequency approximation of Dowell’s equation for the litz-wire winding is derived. Third, a derivation of an analytical equation is given for the optimum strand diameter of the litz-wire winding independent on the porosity factor. Design/methodology/approach – The methodology is as follows. First, the model of the litz-wire bundle is assumed to be a square shape. Than the effective number of layers in the litz wire bundle is derived. Second, the litz-wire winding is presented and an analytical equation for the winding resistance is derived. Third, analytical optimization of the strand diameter in the litz-wire winding is independent on the porosity factor performed, where the strand diameter is independent on the porosity factor. The boundary frequency between the low-frequency and the medium-frequency ranges for both solid-round-wire and litz-wire windings are derived. Hence, useful frequency range of both windings can be determined and compared. Findings – Closed form analytical equations for the optimum strand diameter independent of the porosity factor are derived. It has been shown that the ac-to-dc winding resistance ratio of the litz-wire winding for the optimum strand diameter is equal to 1.5. Moreover, it has been shown that litz-wire winding is better than the solid-round-wire winding only in specific frequency range. At very high frequencies the litz-wire winding ac resistance becomes much greater than the solid-round-wire winding due to proximity effect between the strands in the litz-wire bundle. The accuracy of the derived equations is experimentally verified. Research limitations/implications – Derived equations takes into account the losses due to induced eddy-currents caused by the applied current. Equations does not take into account the losses caused by the fringing flux, curvature, edge and end winding effects. Originality/value – This paper presents derivations of the closed-form analytical equations for the optimum bare strand diameter of the litz-wire winding independent on the porosity factor. Significant advantage of derived equations is their simplicity and easy to use for the inductor designers.

Neuropathic alterations of the myenteric plexus neurons following subacute intraperitoneal administration of salsolinol

Impairment of the enteric nervous system has been suggested to occur within the pathogenesis of neurodegenerative diseases. Thus, in the current study, we consider salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, SAL) as a substance that can potentially induce myenteric neurodegen-eration. Male Wistar rats were subjected to continuous intraperitoneal dosing of salsolinol (200 mg/kg in total) with osmotic mini-pumps for either two or four weeks. An equivalent group of rats served as the control. Jejunal myenteric neurons were subjected to immunofluorescence staining to detect neuron specific protein - protein gene product (pan-neuronal marker, PGP 9.5), nitric oxide synthase (NOS), choline acetyltransferase (ChAT), Bax-protein and alpha-synuclein. In search of any functional impairment within the gastrointestinal tract, gut motility was assessed by determining the residual solid food contents in the stomach and the small and large intestine transit. The myenteric neuron count, the mean size of the neuron body, the area of ganglia and the diameter of nerve strands were decreased in both of the salsolinol-treated groups compared with the controls. The number of NOS-positive cells was lower in the salsolinol-treated groups, while the number of ChAT-positive cells remained unchanged in comparison with the controls. Neurons expressing the pro-apoptotic Bax protein and alpha-synuclein deposits were observed among the myenteric neurons of the salsolinol-treated rats. Salsolinol evokes enteric neuronal cell death via initiation of apoptosis and leads to the formation of pathological aggregates of alpha-synuclein. Impairment of myenteric neurons, mainly the inhibitory motor neurons, might be responsible for the abnormal intestinal transit. Thus, salsolinol might be regarded as a suitable compound for inducing experimental enteric neurodegeneration in rats.

Strand bond stress–slip relationship for prestressed concrete members at prestress release

The transfer of prestress force from prestressing strands to the surrounding concrete is dependent on the bond between the two materials. Understanding the actual bond stress distribution along the transfer length results in optimized design of the transfer zone of prestressed concrete members. Equations of estimating the transfer length in ACI 318 code and AASHTO LRFD bridge design specifications simply take into account the effect of the strand diameter only. The objective of this study is to provide a generalized procedure for determining the bond stress–slip relationship accurately by incorporating the effects of additional parameters, such as concrete compressive strength at prestress release, center-to-center strand spacing, and concrete bottom cover. First, the bond stress distribution along the transfer length of a prestressed concrete member is formulated based on longitudinal slip–strain compatibility, force equilibrium and invariable bond stress–slip relationship along the transfer length. Second, a generalized Inverse Problem-Solving approach is introduced to determine best parameter coefficients through minimizing the discrepancy between the calculated and measured results. Two types of measurements (i.e., transfer length and end slip) reported in the literature are utilized to demonstrate the proposed approach. Predicted transfer length and end slip values using the calibrated bond stress–slip relationship show better agreement with the test data compared to those predicted by ACI 318 code and AASHTO LRFD bridge design specifications. Third, a computational procedure is developed and an example is presented to assist engineers using the developed formulae for determining the bond stress distribution along the transfer length of prestressed concrete members.

Sutures in dermatosurgery

Sutures are a very important component of dermatosurgery. During the three years post graduate curriculum in dermatology, hardly any kind of dermatosurgery or aesthetic dermatology is taught. Aesthetic dermatology is usually not practiced in the medical colleges. But their are some basic surgical techniques, which every dermatologist ought to know. The technique of closing wounds by means of needle and thread is several thousand years old [1]. The history of surgical sutures can be traced back to ancient Egypt where a number of surgical techniques involving sutures were used. There are two types of sutures: Absorbable and Non absorbable. The absorbable sutures include: Polyglactin, Polydiaxonone, PGA and Catgut. The nonabsorbable sutures include nylon, silk and polypropylene [2]. The size of the suture refers to the diameter of the suture strand. The more the zeroes characterizing the suture size, the smaller the resultant strand diameter. The smaller the suture, the lesser the tensile strength of the strand [3]. The suture size ranges from 7 to 11-0. • Size 7 is largest • Size 11-0 is smallest • Size 7-0 approximately corresponds to the thickness of human hair.

Analysis of degradation rate for dimensionless surface area of well-interconnected PCL scaffold via in-vitro accelerated degradation experiment

Until now, many researchers have explained the degradation rate of biodegradable scaffold with respect to several parameters such as porosity, pore size, and strand diameter. In this study, to analyze the degradation rate of Polycaprolactone (PCL) scaffold, accelerated degradation experiment using sodium hydroxide (NaOH) was used. For the experiment, PCL scaffolds were fabricated by bioplotter with respect to porosity, pore size, and strand diameter, respectively. Each fabricated scaffold was put into a vial filled with 5 mol-NaOH 5 mL and trapped-air was removed using vacuum desiccator. After that, all vials were placed in the waterbath which was maintained with 37°C For 24 days, seven vials were taken out from the waterbath for every 2 days and each scaffold was dried after rinsing with D.I. water. Afterwards, the degradation rate was analyzed for each type of PCL scaffolds using the measured mass. Among them, one type of scaffolds, which has the strand diameter of 300 μm and the pitch between strands of 800 μm, was used for the measurement of molecular weight change via gel permission chromatography (GPC). To show the each conventional parameter could not explain alone the degradation rate, the calculated degradation rates were analyzed with respect to porosity, pore size, and strand diameter, respectively. Afterwards, every degradation rate of all types of scaffolds was recorded with respect to the dimensionless surface area which is surface area/ S0. S0 is the surface area of sphere which has same volume of respective scaffold. Consequently, the dimensionless surface area was found to be a single parameter irrelevant to the type of PCL scaffold to explain the in-vitro degradation rate of accelerated NaOH experiment.

Burn rate characterization of iso-propyl nitrate – A neglected monopropellant

An experimental investigation was conducted to characterize the combustion of a monopropellant isopropyl nitrate (IPN). Quartz tubes of 3, 5, 7.5, and 9mm inner diameter and 1mm thickness were utilized to create the strands of varying dimensions. The experiments were conducted in a quiescent atmosphere of air and the ambient pressure was varied from atmospheric pressure to 50bar. Ignition of the IPN strands was achieved by using a heated 60μm Nichrome wire dipped in the liquid and was retracted after ignition. The effect of ambient pressure and strand diameter on the linear burning rates of pure IPN was elucidated. The ambient pressure variation was investigated for a diameter of 5mm, while the diameter-variation was studied at 1, 10, 20, and 40bar. The linear burning rate of IPN strands of 5mm diameter was found to exhibit two distinct regimes, where a steep rise in burning rate with pressure was observed after an initial decreasing trend. The values of the burn rates increased with a pressure exponent of 1.54, from approximately 0.2mm/s at atmospheric pressure to 1.6mm/s at 50bar. In the first stage, the burn rates were found to be controlled by diffusion-dominated combustion, characterized by a single bipropellant flame up to a pressure of 10bar, beyond which monopropellant-dominated combustion was found to be dominant in the second stage, with a distinct monopropellant flame and a bipropellant flame. The bipropellant flame was found to exhibit an oscillatory behavior in the second stage of combustion. A semi-empirical model was utilized successfully to predict the experimental burn rates of IPN in both regimes. The burn rates were found to depend on the strand diameters under the conditions applied, with a generalized decreasing trend at high pressures and atmospheric pressures, and an initial decrease followed by an increase at intermediate pressures.

The effect of the strand diameter on the damping characteristics of fiber reinforced polymer matrix composites: Theoretical and experimental study

The damping property of glass fiber reinforced polymer matrix composites with two different strand/fiber diameters, their different orientations and layups are investigated. It is found that the damping can be improved at the negligible expense of stiffness, by generating more number of interfaces, i.e., reducing the fiber diameter from 27.2µm to 18.3µm without compromising the dimensions of the composite specimen and the volume fraction of the fiber in the specimens. The natural frequencies and loss factors have been evaluated from experimental results, using the impulse technique. The same properties have also been evaluated theoretically by performing modal analysis, using Blevins׳ “Formulas for Natural Frequency and Mode Shape”, and the three phase damping analysis using Ni and Adams׳s “the Specific Damping Capacity (SDC) model” and Gu et al. ׳s “the interfacial adhesion model” in the energy dissipation relationship. A good agreement exists between the experimental and theoretical values.

Parametric Study of Transmission Line Fitting Vibration Damper Based on Modal Analysis

&lt;p&gt;This paper is related to the vibration analysis of transmission line fitting vibration damper (TLFVD) using commercial ANSYS program. According to the basic structure of the TLFVD, the three dimensional model with different parameters including diameter and length of strand is established. Through the modal analysis of the TLFVD using ANSYS WORKBENCH, the first four-order natural frequencies and mode shapes is obtained. Comparing the simulation data of vibration characteristics, the effects of model parameters on the natural frequency are summarized. Finally, the optimized model has been selected from various models established, and the resonant frequency of the TLFVD was verified by the harmonic response analysis. As a result, the optimized model structure of the TLFVD is presented.&lt;/p&gt;

ITER &lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$\hbox{Nb}_{3}\hbox{Sn}$&lt;/tex&gt;&lt;/formula&gt; and NbTi Strands Benchmarking at ASIPP

To ensure accurate and consistent measurement of the physical and superconducting properties of the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn and NbTi composite strand, a strand test facility benchmarking effort for the International Thermonuclear Experimental Reactor (ITER) was initiated in August 2008. Three rounds of benchmarking have been finished. The first round was referred to as the bronze-route Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strand, while the second and third benchmarking were referred to as Internal Tin Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn and NbTi strand, respectively. As the referenced lab of the Chinese Domestic Agency, the superconducting strand test lab from the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) participated in all the three rounds of benchmarking. The benchmarking includes tests for critical current (IC), n-index, hysteresis loss, Residual Resistivity Ratio (RRR), strand diameter, Cu fraction, twist pitch (TP), twist direction, and metal plating thickness. The results from ASIPP were acceptable except for the RRR measurements on Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strands for the first and second benchmarking. Improvements have been made mainly for RRR and TP measurements, and the test reports for the third benchmarking were approved by the ITER organization. The test facility and test results were presented in this paper.

Implementation of 0.7 in. diameter strands at 2.0 × 2.0 in. spacing in pretensioned bridge girders

Implementation of 0.7 in. diameter strands at 2.0 × 2.0 in. spacing in pretensioned bridge girders

Investigation of Frictional Force Applied to Strands Surrounded by Other Strands and Tribological Analysis of Contact Surface in CIC Conductor

At the SULTAN test facility, the assessment of the performance of toroidal field coils has been progressing. Unpredictable strand buckling was observed during the destructive investigation of the conductor after significant degradation of the current sharing temperature. The buckling direction was perpendicular to the Lorentz force (LF), and the mechanism causing this was due to the thermal shrinkage occurring because of the difference in the thermal contraction between the strand material and the stainless steel conduit. Our previous research was based on a two-dimensional string model and demonstrated that the observed 2 mm strand bending could have led to strand buckling if the total amount of slide at the contact crossover was assumed to be 80 μm. To verify this assumption, we fabricated a device for the measurement of the friction force (shear force) between strands under a constriction force comparable to the LF of several hundred of kilonewtons per meter. The results for a Cr-coated 0.89 mm diameter strand surrounded by bare Cu strands indicated that the thermal contraction force would be sufficient to overcome the static friction force when the contraction force is reduced to a tenth of the maximum LF. The mechanism of the slide motion could be divided into two processes: separation of the inner wall of the conduit and the gradual separation from other strands due to a gradual reduction of the LF. A tribological analysis revealed that the real contact area increases by 10% when the shear force is applied; this result would help us evaluate the contact resistance between strands of conductors.

A little hard to swallow? The use of nanotechnology in the food industry might be both boon and bane to human health.

Eating a ‘grey goo’ of nanoparticles may seem unpalatable, but the food industry believes that nanotechnology could deliver commercial benefits for the processing and preservation of food (Fig 1). However, as with all new technologies, the question arises as to whether ingesting such particles—some of which are being used to kill microorganisms in food—might also have potential negative effects on human health. Because of major food‐producers' increasing interest in nanotechnology, the question is becoming relevant to researchers as well as regulators. Figure 1. Potential benefits of using nanotechnology in the food industry > … the food industry believes that nanotechnology could deliver commercial benefits for the processing and preservation of food Nanotechnology involves the use of extremely small particles that range from a few nanometres in size—roughly half the diameter of a DNA strand—to 100s of nanometres—about the size of cell organelles and viruses. Nanoparticles per se are not man‐made, as they occur naturally in various forms such as oceanic spray and fine sand. Human‐engineered particles have been around for years in cosmetics, sunscreens and cleaning products. Now, however, the food industry wants to use nanotechnology to extend the freshness of products, detect spoilage and inhibit the growth of microorganisms. Given this, the US Food and Drug Administration (FDA) has issued a non‐regulatory ‘guidance’ asserting the critical need to better understand the reactivity of engineered nanoparticles. The agency is specifically concerned about the ‘deliberate manipulation and control of particle size’ as such materials might have an impact on public health and safety (http://www.fda.gov/regulatoryinformation/guidances/ucm257698.htm). Many critics of the food industry's use of nanotechnology think the guidance document is not sufficient and that the US government should take regulatory action. Among them is J. Clarence Davies, who chaired the US National Academy of Sciences' Committee on Decision Making for Regulating Chemicals in the Environment and who was involved in creating the US …

Splice length of prestressing strands in field-cast UHPC connections

The development length of reinforcement embedded into ultra-high performance concrete (UHPC) can be significantly shorter than the lengths normally associated with conventional concrete. Shortening the development length of prestressing strands can allow for a redesign of some structural systems, including spliced girder and continuous-for-live-load bridges. UHPC, when used in field-cast connections between prefabricated elements, can create robust connections which emulate monolithic components. This study investigated the development length of 12.7- and 15.2-mm diameter untensioned prestressing strands embedded in steel fiber and PVA fiber reinforced UHPC. The volumetric fiber content was 2 %. A novel tension test method allowed for replication of the stress state that occurs when strands are lap spliced within a connection between two linear elements. The results suggest that, for the steel fiber reinforced UHPC, the 12.7-mm diameter strands can be fully developed within 51 cm and the 15.2-mm diameter strands can be fully developed in approximately 61 cm. The 12.7-mm diameter strands can be fully developed in the PVA fiber reinforced UHPC in approximately 91 cm. Applying UHPC to create lap splice connections of prestressing strands may allow for increased structural efficiency and increased structural redundancy through the use of simple, non-congested, non-post-tensioned connection details.

Abstract W P76: Parent Artery Curvature May Help Determine the Effectiveness of Flow Diverter Treatment

Introduction: Flow diverters (FDs) aim to treat intracranial aneurysms by altering intra-aneurysmal hemodynamics. Reports have suggested aneurysm and parent artery shape may affect flow reduction in FD-treatment. The purpose of this study is to gain insight into the way in which aneurysm shape and parent artery curvature influence the ability of FDs to redirect flow. Hypothesis: Aneurysm dome size and parent artery curvature affect FD-induced flow reduction within an aneurysm. Methods: FD models constructed based on the Pipeline Embolization Device with 35% area coverage, 30 um strand diameter, and 4 mm nominal diameter were implemented for hemodynamic simulation analysis. The flow reduction effects were tested using aneurysm models featuring different dome sizes and parent artery curvatures. Aneurysm blood flow was analyzed before and after FD stenting in regions of the aneurysm neck, body, and dome. Results: We found that aneurysms with higher parent artery curvature had increased systole flow volume entering aneurysms before and after stenting, regardless of aneurysm size, with pre-FD volume flow rates for curvatures of 20 and 30 degrees, respectively, 1.54 and 2.40 times those for 10 degree curvature. Furthermore, FD reduced flow less in aneurysms with higher curvature. For parent artery curvatures of 10, 20, and 30 degrees, overall reductions of flow volume entering the aneurysm were 91.1±0.56%, 88.2±1.2%, and 85.5±0.28%, respectively. 97.2% of models had more flow reduction at the aneurysm dome than neck. Figure 1 shows representative, post-FD flow in 10 and 30 degree parent arteries, with a greater volume flow rate in (b) depicted by denser streamlines. Aneurysm dome size was not found to have a significant effect on volume flow rate. Conclusions: We found that artery curvature may have a large influence on FD flow reduction, indicating that FD may be less effective at reducing blood flow entering aneurysms located within higher curvature arteries.

Structure of solar coronal loops: from miniature to large-scale

We will use new data from the High-resolution Coronal Imager (Hi-C) with unprecedented spatial resolution of the solar corona to investigate the structure of coronal loops down to 0.2 arcsec. During a rocket flight Hi-C provided images of the solar corona in a wavelength band around 193 A that is dominated by emission from Fe XII showing plasma at temperatures around 1.5 MK. We analyze part of the Hi-C field-of-view to study the smallest coronal loops observed so far and search for the a possible sub-structuring of larger loops. We find tiny 1.5 MK loop-like structures that we interpret as miniature coronal loops. These have length of the coronal segment above the chromosphere of only about 1 Mm and a thickness of less than 200 km. They could be interpreted as the coronal signature of small flux tubes breaking through the photosphere with a footpoint distance corresponding to the diameter of a cell of granulation. We find loops that are longer than 50 Mm to have a diameter of about 2 arcsec or 1.5 Mm, consistent with previous observations. However, Hi-C really resolves these loops with some 20 pixels across the loop. Even at this greatly improved spatial resolution the large loops seem to have no visible sub-structure. Instead they show a smooth variation in cross-section. The fact that the large coronal loops do not show a sub-structure at the spatial scale of 0.1 arcsec per pixel implies that either the densities and temperatures are smoothly varying across these loops or poses an upper limit on the diameter of strands the loops might be composed of. We estimate that strands that compose the 2 arcsec thick loop would have to be thinner than 15 km. The miniature loops we find for the first time pose a challenge to be properly understood in terms of modeling.

Camber of Skew Precast Prestressed Concrete Bridge Deck Panels

A common problem that most contractors are faced with in slab-bridges’ construction is to predict camber of pre-tensioned or post-tensioned corrugated skew slabs due to prestressing force. It is an important factor to achieve bridge design finished levels without any unforeseen construction cost. Presence of skewedness in bridges makes analysis and design of bridge decks intricate. In this paper, three 3100 mm long post-tensioned corrugated slabs with overall height of 200 mm and 50 mm thickness for both inclined and top parts of specimens, and thickness of 77 mm in the bottom part were studied. Corrugation angle of tested slabs was 60° and skew angle was 20°. Specimens are prestressed by two 15.25 mm diameter strands. Camber measurements were carried out during tests by means of measuring the differences of slab bottom levels. Numerical calculation is done utilizing the Finite Element Analysis Program; ANSYS, taking into consideration initial prestress losses. ANSYS program provides a threedimensional element (Solid 65) with nonlinear model of brittle materials similar to concrete material. Three-dimensional spar element was used for modeling reinforcement and prestressed strands. Comparison between experimental and numerical results is made. Numerical results showed good agreement with experimental results. Keywords: Slab, Concrete, Prestress, Skew, Camber, Post-tensioned, Experimental, Numerical, Non-linear.

Test of Optimized 120-mm LARP $\hbox{Nb}_{3}\hbox{Sn}$ Quadrupole Coil Using Magnetic Mirror Structure

The U.S. Large Hadron Collider accelerator research program is developing a new generation of large-aperture high-field quadrupoles based on Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductor for the high-luminosity upgrade of the Large Hadron Collider. Tests of the first series of 120-mm-aperture high-gradient quadrupole (HQ) coils revealed the necessity for further optimization of the coil design and fabrication process. Modifications in coil design were gradually implemented in two HQ coils previously tested at Fermi National Accelerator Laboratory using a magnetic mirror structure (HQM01 and HQM02). This paper describes the construction and test of an HQ mirror model with a coil of optimized design and with an interlayer resistive core in the conductor. The cable for this coil was made of a smaller diameter strand, providing more room for coil expansion during reaction. The 0.8-mm strand, used in all previous HQ coils, was replaced with a 0.778-mm Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strand of RRP 108/127 subelement design. The coil was instrumented with voltage taps, heaters, and strain gauges to monitor mechanical and thermal properties and quench performance of the coil.