Straight Samples Research Articles

Assessment of a three step process using tungsten catalyzed hydrogen peroxide-based oxidative desulfurization for commercial diesel fuels

A three-step oxidative desulfurization (ODS) process comprising of oxidation, liquid–liquid extraction, and adsorption was applied to two compositionally very different commercial diesel samples, namely a straight run middle distillate and a blend of primary and secondary refining streams, to assess the ODS process feasibility. The oxidation of sulfur compounds was achieved using hydrogen peroxide as an oxidant in the presence of tungstic acid catalyst. The diesel feedstocks, intermediate and final products were characterized in detail using standard analytical methods along with state-of-the-art speciation techniques. Under mild conditions (ambient pressure and 80 °C), ODS was found to target sulfur species that are refractory to low-severity hydrodesulfurization (HDS), specifically dibenzothiophenes. The ODS process removed 85.3% and 33.5% of the sulfur compounds in the blend and straight run diesel samples, respectively. A comprehensive material balance for the overall process and each process step was also established, revealing that approximately 80% of the initial diesel could be recovered after desulfurization, when accounting for the removed sulfur compounds. However, any extraction based desulfurization approach has an inherent limit for the achievable overall diesel recovery because of the potentially high mass fraction of organosulfur compounds that is removed in the process. Consequently, ODS should be preceded by an HDS process to target the main bulk of sulfur compounds while the ODS process then removes the remaining HDS refractory compounds. Removal of nitrogen species, which are also undesirable in the final product, was a positive side effect of the studied ODS process.

Aerosol size distribution measurement of electronic cigarette emissions using combined differential mobility and inertial impaction methods: Smoking machine and puff topography influence.

A combination of a real-time high resolution aerosol differential mobility spectrometer (DMS500) and an electrical low pressure impactor (used as a traditional impactor) was applied to simultaneously collect real-time data and analyze particle size by weighing the mass of the aerosol collected on the impactor stages. Nonrefillable fixed-power as well as refillable and power adjustable e-cigarettes (e-cigs) were tested at various puffing flow rates. Two types of smoking machines were used: a smoke cycle simulator that provides instantaneous straight sample delivery to the analyzer and a Human Profile Pump that utilizes two synchronized pistons and operates by sample pull-push mode. Chemical analysis of the major components of e-liquid (propylene glycol, vegetable glycerol, water, and nicotine) was made using a proton nuclear magnetic resonance method. Limited amounts of samples collected on impactor stages were analyzed by liquid chromatography time-of-flight mass-spectrometry to find newly formed semi- or low-volatile organic compounds in e-cig aerosol and by transmission electron microscopy to check for the presence of nanoparticles in e-cig emissions. Differential mobility and inertial impaction methods showed comparable particle size results. Method of aerosol generation (type of the smoking machine) as well as puffing topography affected the e-cig particle size. Newly formed semi- or low-volatile organic compounds as well as metal nanoparticles were found in e-cig aerosol.

Preparation and mechanical performance of small-diameter PHBHHx vascular graft by electrospinning

The straight and corrugated PHBHHx (Poly(3-hydroxybutyrate-co-3-hydroxhexanoate)) vascular grafts with 6 mm inner diameters were prepared successfully by electrospinning. Moreover, their mechanical behaviors were investigated compared with the commercial vascular grafts (SW-ePTFE woven). Electrospun PHBHHx fibers had a submicron scale. Straight grafts and SW-ePTFE grafts exhibited higher Young’s modulus and tensile breaking strength in the circumferential direction than the corrugated grafts, but the break and elastic recovery rate were lower. Both the straight and corrugated samples had lower suture strength than the SW-ePTFE samples, but still satisfied the requirement of transplantation of small diameter vascular. The compliance of corrugated grafts was similar to SW-ePTFE grafts and lower than straight grafts. The results of hemolytic and cytotoxicity tests demonstrated that both the straight and corrugated grafts had good hemocompatibility and no cytotoxicity. Therefore, the results of this study showed the potential application of electrospun PHBHHX vascular grafts as small diameter vascular grafts.

Cryopreservation of amniotic membrane with and without glycerol additive.

Amniotic membrane (AM) is an essential tool in ocular surface reconstruction. In this study, we analyzed the differential effects of glycerol and straight storage at - 80°C for up to 6months on the structural, biological, and mechanical properties of amniotic membrane (AM). Human placentae of 11 different subjects were analyzed. AMs were stored at - 80°C, either with a 1:1 mixture of Dulbecco's modified Eagle medium and glycerol (glycerol) or without any medium or additives (straight). Histological image analysis, tensile strength, cell viability, and basic fibroblast growth factor (bFGF) secretion were evaluated at 0.5, 1, 3, and 6months. Histologically, neither glycerol nor straight storage significantly altered the epithelial or stromal structure of the AM. However, the cell number of the stroma was significantly reduced during the freezing process, independently of the storage method (p =0.05-0.001). Tensile strength and Young's modulus were not influenced by the storage method, but longer storage periods significantly increased the tensile strength of the AMs (p = 0.028). Cell viability was higher in glycerol rather than straight AM samples for up to 3months of storage (p =0.047-0.03). Secretion of bFGF at 3months of storage was significantly higher in glycerol versus straight frozen AM samples (p =0.04). Glycerol led to higher cell viability and higher bFGF secretion for up to 3months of AM storage. However, no significant differences between the two methods were observed at 6months of storage at - 80°C.

Statistical Analysis of Rock Fracture Toughness Data Obtained from Different Chevron Notched and Straight Cracked Mode I Specimens

In laboratory fracture toughness studies, the crack growth resistance of rock materials may be influenced by different factors such as specimen geometry, loading conditions, and also the type of pre-notch cut in the test sample. In this paper, a large number of mode I fracture toughness experiments are conducted on an Iranian white rock “Harsin marble” with six different mode I specimens. The selected test specimens are in the shape of cylindrical rod, rectangular beam, and circular Brazilian disk containing either chevron notch or straight crack. The effect of specimen geometry and pre-notch type was investigated statistically, and it was found that the average fracture toughness values of notched specimens were higher than those of the similar specimens but containing straight crack. Meanwhile, the scatters of fracture toughness data for chevron notched specimens were smaller than those for the straight cracked samples. For each set of experimental fracture toughness results, probability of fracture was investigated using two- and three-parameter Weibull statistical distributions. Comparison of the Weibull fitted curves for chevron notched and straight cracked samples with the same geometries demonstrated that the discrepancy between the corresponding curves can be described with a good accuracy by a simple shift factor. In addition, using the extended maximum tangential strain criterion which takes into account the influence of both KI and T-stress terms, the statistical fracture toughness data of chevron notched specimens were predicted in terms of the Weibull distribution parameters of the straight cracked specimens.

Effect of Ethanethiolate Spacer on Morphology and Optical Responses of Ag Nanoparticle Array-Single Layer Graphene Hybrid Systems.

Single layer graphene (SLG) and two-dimensional (2-D) plasmonic Ag nanoparticle arrays assembled by chemisorption of ethanethiol (ET) molecules (AgNPs-ET) were employed as components of two types of hybrid systems designed for surface-enhanced Raman scattering (SERS) spectral probing of SLG localized in the vicinity of plasmonic NPs. Both hybrids were characterized by optical microscopy, transmission electron microscopy (TEM), surface plasmon extinction (SPE), and SERS microRaman spectral measurements at four excitation wavelengths spanning the 445-780 nm range. SERS spectral probing of the glass/SLG/AgNPs-ET hybrid prepared by overdeposition of SLG on glass by the array of ET-modified Ag NPs has shown that the chemisorbed ET acts as an efficient molecular spacer between SLG and Ag NPs surface which, in turn, enabled to obtain SERS spectra of SLG unperturbed by doping or strain. TEM imaging and SERS spectral probing of the second hybrid prepared by overdeposition of AgNPs-ET array on glass by SLG revealed removal of the adsorbed ET molecules and annealing of Ag NPs during the SLG deposition. The characteristics of the resulting glass/AgNPs/SLG hybrid system, namely (i) broad distribution of the annealed Ag NPs sizes and shapes, (ii) SPE curve covering the overall visible spectral region, (iii) absence of the ET spectral bands in SERS spectra, and (iv) fairly uniform SERS enhancement of the G and 2D mode of SLG in the 532-780 nm range in the straight sample geometry indicate that this hybrid can provide a suitable platform for investigation of the excitation wavelength dependence of combined SERS/GERS (graphene-enhanced Raman scattering) enhancement experienced by various molecular species brought into contact with SLG in this hybrid. Finally, weak optical effects attributed to increased reflectivity of SLG in the near field of Ag NPs arrays have been observed in the excitation wavelength dependence of the SERS spectra of both types of hybrid systems.

Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: II. High-strength, laminated Ag-sheathed Bi-2223 tapes

In article I of this series, we described a spiral coil quench technique for probing the influence of the superconductor stress and strain state during normal operation on its margin to degradation during a quench and applied to a Bi-2212 round wire. Here we extend this technique to study the failure mechanisms and limits of high-strength Bi-2223 tapes experiencing a quench while carrying a large current in a high magnetic field. In contrast to Bi-2212 magnets made via a wind-and-react technique for which bending strains can be ignored, Bi-2223 magnets are made with a react-and-wind technique for which bending strain is significant. The critical tensile stress of Bi-2223 tapes (type HT-NX) decreases from >440 MPa for straight samples to 185 MPa after being bent to a diameter D of 50 mm. For HT-NX tapes with D = 50 mm, the quench degradation limit, measured using maximum allowable temperature during a quench Tallowable, is greater than 300 K for axial tensile stress < 94 MPa; it decreases with increasing tensile axial stress nonlinearly, dropping to 230 K for = 125 MPa. Tallow able experimental data at D = 50 mm is consistently predicted by a general strain model that assumes that quench degradation in NX/Bi-2223 is driven by axial tensile strain in Bi-2223 filaments exceeding the irreversible strain limit. The Tallowable is then predicted for various D including D = 80 mm important for NMR magnets. The given Tallowable is easy to use and important for finding the balance between operation stress, and therefore magnetic field generation efficiency, and operation margin when designing a superconducting magnet using Bi-2223 tapes.

Self-monitoring ‘SMART’ (RE)Ba2Cu3O7−x conductor via integrated optical fibers

A self-monitoring, SMART (RE)Ba2Cu3O7−x (REBCO) conductor has been created by integrating optical fibers into the solder fillet of the current REBCO conductor architecture. By interrogating the integrated optical fiber by Raleigh backscattering, a spectral shift signal as a function of time and position along the conductor is obtained. Due to the direct integration into the solder fillet, intimate, consistent contact between fiber and conductor is obtained, while the optical fiber is protected and does not take up any space in the magnet winding. Therefore, the SMART conductor enhances the benefits of the co-wound fiber approach and provides ultimate sensitivity and practicality. Several samples of SMART REBCO conductor have been manufactured and characterized. The strain self-sensing capabilities have been demonstrated as well as thermal perturbation detection and localization with 2.56 mm spatial resolution. Results show that a key feature of the SMART conductor concerns its sensitivity to thermal perturbation; unlike in the case of a coil with co-wound optical fiber, the SMART REBCO sensitivity increases as the temperature decreases. A series of quench measurements have been performed, both on straight samples and on a pancake coil, at temperatures as low as 14.6 K. Using the data collected by the SMART REBCO during quench experiments, the temporal evolution of the size of a normal zone and the instantaneous normal zone propagation velocity have been calculated.

An investigation of the effective parameters causing the critical current drop in a small high temperature superconducting D-shaped coil

In this paper, the dependency of the critical current on the magnetic field, temperature, and different curvature radii for a specific sample of Bi-2223/AgMg composite tape are investigated. By using this superconducting tape, a D-shaped pancake coil is designed and built. The coil critical current degradation at liquid nitrogen temperature with respect to a straight short sample of the same tape is reported, and also the portion of the bending and self-field contribution in the critical current drop is indicated separately. The hysteresis behavior as a function of the current rate during ramp up and ramp down cases on the voltage-current curve at liquid nitrogen temperature is examined. In addition, the quenching propagation speed is measured at two different radii of curvature of the designed magnet.

Optimal approaches for inline sampling of organisms in ballast water: L-shaped vs. Straight sample probes

Both L-shaped (“L”) and straight (“Straight”) sample probes have been used to collect water samples from a main ballast line in land-based or shipboard verification testing of ballast water management systems (BWMS). A series of experiments was conducted to quantify and compare the sampling efficiencies of L and Straight sample probes. The findings from this research—that both L and Straight probes sample organisms with similar efficiencies—permit increased flexibility for positioning sample probes aboard ships.

Characterization of the ITER CS conductor and projection to the ITER CS performance

The ITER Central Solenoid (CS) is one of the critical elements of the machine. The CS conductor went through an intense optimization and qualification program, which included characterization of the strands, a conductor straight short sample testing in the SULTAN facility at the Swiss Plasma Center (SPC), Villigen, Switzerland, and a single-layer CS Insert coil recently tested in the Central Solenoid Model Coil (CSMC) facility in QST-Naka, Japan. We obtained valuable data in a wide range of the parameters (current, magnetic field, temperature, and strain), which allowed a credible characterization of the CS conductor in different conditions. Using this characterization, we will make a projection to the performance of the CS in the ITER reference scenario.

Cyclic load effect on round strands made by twisted stacks of HTS tapes

Various DC tests performed recently with full-size 60kA HTS cable prototypes in the EDIPO test facility demonstrated that proposed design of HTS strand at Swiss Plasma Center (SPC) – stack of HTS tapes twisted and soldered between two copper profiles – is applicable for high-current fusion cables, but improvement of the strand mechanical properties against the cyclic loading is still needed. Based on experimentally obtained correlation between the performances of cable prototypes at different operating conditions, further investigation of cyclic transverse load on the strand performance was performed at 77K. Aiming to obtain a strand design able to withstand a continuous cyclic load operation of some thousand cycles, influence of the strand geometry and tape's manufacturer has been studied. Cyclic load has been applied up to 1000 cycles for straight and bent samples at the load amplitudes up to 4MPa. Based on the obtained data, next design of HTS cable prototype will be discussed.

A feasibility study of high-strength Bi-2223 conductor for high-field solenoids

We performed a feasibility study on a high-strength BiPbxSr2Ca2Cu3O(Bi-2223) tape conductor for high-field solenoid applications. The investigated conductor, DI-BSCCO Type HT-XX, is a pre-production version of Type HT-NX, which has recently become available from Sumitomo Electric Industries. It is based on their DI-BSCCO Type H tape, but laminated with a high-strength Ni-alloy. We used stress–strain characterizations, single- and double-bend tests, easy- and hard-way bent coil-turns at various radii, straight and helical samples in up to 31.2 T background field, and small 20-turn coils in up to 17 T background field to systematically determine the electro-mechanical limits in magnet-relevant conditions. In longitudinal tensile tests at 77 K, we found critical stress- and strain-levels of 516 MPa and 0.57%, respectively. In three decidedly different experiments we detected an amplification of the allowable strain with a combination of pure bending and Lorentz loading to (calculated elastically at the outer tape edge). This significant strain level, and the fact that it is multi-filamentary conductor and available in the reacted and insulated state, makes DI-BSCCO HT-NX highly suitable for very high-field solenoids, for which high current densities and therefore high loads are required to retain manageable magnet dimensions.

Deflection Analysis of Different Needle Designs for Prostate Biopsy and Focal Therapy.

The biopsy needles currently used were designed for a transrectal biopsy and are known to experience significant deflection from the point of entry into the gland to the needle tip. Five designs were selected for testing: 18-gauge Bard, 15-gauge lancet tip needle with 12° vet-point cannula, and trocar tip needle with 12°, 15°, and 20° vet-point cannulas. The 15-gauge needle was designed to take a variable specimen sample between 20 and 60 mm, whereas the Bard needle specimen bed was fixed at 20 mm. The needles were bench tested on a spring-loaded platform and fired into gelatin matrix with modulus of elasticity similar to human prostate. The Bard device with lancet tip needle deflected an average of 0.9 mm (range 0.3-1.3 mm) and 1.9° (range 0.6°-2.8°). Increasing needle diameter from 18-gauge Bard to 15-gauge variable with the same lancet tip needle design resulted in an average deflection across the 3 test lengths of 0.9 mm (range 0-2.0 mm) and 0.9° (range 0°-2.0°) with no significant difference. On the contrary, the use of the 3-point trocar tip needles with 12°, 15°, and 20° vet-point cannulas demonstrated significant reduction in the extent of deflection in both millimeters and degrees. There was no deflection at the 2- and 4-cm shots for both spring loads and preloads for the 3 vet tip angles tested. At 6 cm, the 20° vet tip performed the best. We proposed a mechanism that provides more accurate prostate sampling by combining a 3-point trocar tip on the needle with a 20° vet tip on the cutting cannula. Using the phantom, mimicking prostate gland tissue density, no deflection was revealed between 20- and 60-mm biopsy lengths, which should permit a straight sample in the majority of prostate glands and improve cancer localization for focal therapy planning.

Fishbone-Like High-Efficiency Low-Pass Plasmonic Filter Based on Double-Layered Conformal Surface Plasmons

In this work, we report a fishbone-like high-efficiency low-pass plasmonic filter based on a double-layered conformal surface plasmon waveguide (CSPW) which consists of double-layered symmetrical metal gratings (SMGs) of fishbone shape. Efficient mode conversion between the quasi-transverse electromagnetic (TEM) waves in the microstrip line and the conformal surface plasmons (CSPs) on the double-layered CSPW is realized by using gradient double-layered SMGs and impedance matching technique. Experimental results of the transmission and reflection coefficients of the straight sample show excellent loss-pass performance and agree well with the numerical simulations. The curved samples exhibit low radiation loss when the double-layered CSPW is conformal or even bent thanks to the high confinement of CSPs. The proposed structure can find potential applications in integrating conventional circuits with CSPs devices at microwave and terahertz frequencies.

Bending strain tolerance of MgB2 superconducting wires

This work describes the strain tolerance of MgB2 superconductors subjected to variable bending stresses. Bending of MgB2 wire was done at room temperature in different modes: (i) direct bending of straight annealed samples to variable diameters and by (ii) indirect bending by straightening of bent and annealed samples. Ic–bending strain characteristics of samples made by in situ PIT and by the internal magnesium diffusion (IMD) process were measured at 4.2 K. The results show a good agreement between the direct and indirect bending mode, which allows easier estimation of limits important for the winding process of MgB2 superconductors with brittle filaments. A comparison of MgB2 wires made by in situ PIT and IMD processes showed improved strain tolerance for IMD due to better grain connectivity the low annealing temperature, which does not appear to reduce the mechanical strength of sheath material.

The strengthening effect of inter-layer cold working and post-deposition heat treatment on the additively manufactured Al–6.3Cu alloy

Wire + Arc Additive Manufacture (WAAM) attracts great interest from the aerospace industry for producing components with aluminum alloys, particularly Al–Cu alloy of the 2000 series such as 2219 alloy. However the application is restricted by the low strength properties of the as-deposited WAAM metal. In this study two strengthening methods were investigated – inter-layer cold working and post-deposition heat treatment. Straight wall samples were prepared with 2319 aluminum alloy wire. Inter-layer rolling with loads of 15kN, 30kN and 45kN were employed during deposition. The ultimate tensile strength (UTS) and yield strength (YS) of the inter-layer rolled alloy with 45kN load can achieve 314MPa and 244MPa respectively. The influence of post-deposition T6 heat treatment was investigated on the WAAM alloy with or without rolling. Compared with inter-layer rolling, post-deposition heat treatment can provide much greater enhancement of the strength. After T6 treatment, the UTS and YS of both of the as-deposited and 45kN rolled alloys exceeded 450MPa and 305MPa respectively, which are higher than the properties of the wrought 2219−T6 alloy. The strengthening mechanisms of this additively manufactured Al–6.3Cu alloy were investigated through microstructure analysis.

Plan for Testing High-Current Superconductors for Fusion Reactors with A 15T Test Facility

Fusion power plants need larger scale and higher field superconducting magnets than the ITER magnets. Therefore, higher current superconductors with high strength against strong electromagnetic forces are needed. In order to examine the superconducting properties of such large conductors in real conditions, we are preparing a new test facility that is equipped with a solenoid coil of the highest field of 13 T with the bore of 0.7 m, a pair of temperature-variable current leads, and a vacuum chamber for conductor samples. The highest field can be increased to 15 T by installing an additional coil with the cold bore of 0.6 m. Since the inlet temperature of the samples can be varied from 4.4 K to 50 K, it is possible to examine properties of advanced conductors at actual operating temperatures including high-temperature superconductors. We propose coil-shaped conductor samples instead of straight samples in order to apply electromagnetic hoop forces on the conductors to realize the real condition. A reference design of a sample for a cable-in-conduit conductor is provided.

Magnetic field measurements of JT-60SA CS model coil

In a cold test of the JT-60SA CS model coil, which has a quad-pancake configuration consisting of a Nb3Sn cable-in-conduit (CIC) conductor, magnetic fields were measured using Hall sensors. For a holding coil current of 20kA, measured magnetic fields varied slightly with long time constants in the range 17–571s, which was much longer than the time constant derived from a measurement using a short straight sample. To validate the measurements, the magnetic fields of the model coil were calculated using a computational model representing the positions of Nb3Sn strands inside the CIC conductor. The calculated results were in good agreement with the measurements. Consequently, the validity of the magnetic field measurements was confirmed. Next, we investigated other coils consisting of CIC conductors and having long time constants. The only commonality among the coils was the use of CIC conductors. At present, there is no obvious way to prevent generation of such magnetic-field variations with long time constants.

Computational Fluid Dynamics (CFD) Analysis of the Helium Inlet Mock-Up for the ITER TF Superconducting Magnets

The final design for the inlets of the supercritical He (SHe) coolant of the toroidal field (TF) superconducting magnets of the International Thermonuclear Experimental Reactor (ITER) has to be evaluated on the basis of different aspects, including the interest to minimize the associated localized pressure drop. Based on previous experience made on the analysis of the SHe inlets for the ITER superconducting central solenoid, we have developed and applied a computational fluid dynamics (CFD) model to compute the pressure drop versus mass flow rate characteristic in the TF inlet mock-up which was recently tested at CEA Cadarache, France. The cable model is first calibrated and verified against experimental data from short straight samples. The calibrated model is then applied to the inlet geometry and the results of the calculation are compared with the available measurements, showing very good agreement for sufficiently anisotropic permeability of the cable region. The thus validated model is finally used to investigate the distribution of the coolant flow among the different petals and the central channel, downstream of the inlet, as well as to quantitatively assess the role of the petal wrapping on the localized pressure drop at the inlet.