Stainless Steel Rods Research Articles

Induced-charge electro-osmosis of polymer-containing fluid around a metallic rod

Induced-charge electro-osmotic (ICEO) flow of polymer-containing electrolyte solution around a cylindrical gold-coated stainless steel rod under AC electric field is measured by micro-particle image velocimetry (micro-PIV) for the first time. The ICEO flows as functions of the amount of non-ionic PEG (polyethylene glycol), cationic PDADMA (polydiallyldimethylammonium chloride), and anionic PVSASS (polyvinylsulfonic acid sodium salt) polymers added into the salt solution, frequency, and strength of the AC electric field are measured. The ICEO flow of polymer-containing fluid around the rod is quadrupolar with four vortices and is proportional to the square of imposed electric field. The ICEO flow velocity exponentially decreases with an increased concentration of neutral PEG. Ionic polyelectrolytes significantly increase ICEO velocities due to the enriched net charge within the induced electric double layer arising from the electrostatic interaction between the polarized rod’s surface and the charged polyelectrolytes in ionic polymer solution. In addition, polymer concentration affects the dependence of the ICEO flow on the frequency of AC electric field.

Joining of 316L stainless steel by using spark plasma sintering method

Spark plasma sintering equipment was used to join 316L stainless steel rods with or without a powder interlayer. The powder layer with high electrical resistance was assumed to act as an effective local heat source. Resistance measurements of powders at room temperature showed that the resistance increased by orders of magnitude compared to the bulk material. The parameters influencing the joining process including current (heating power), heating time, pressure, pulse sequence, particle size and powder amount have been investigated. Results showed that especially by rightly adjusting current and heating time, high strength joint can be obtained. By applying only small pressure, deformation of the joint could be avoided. With a thicker powder interlayer, the distortion of the sample could be reduced, and powders with small particle size can produce higher strength samples. By adjusting all these parameters, samples with high strength can be obtained within seconds, so that the heat-affected zone can be markedly reduced.

Corrosion Behavior of Construction Materials for Intermediate Temperature Steam Electrolysers

Different corrosion resistant stainless steels, nickel-based alloys, pure nickel, Ta-coated stainless steel (AISI 316L), niobium, platinum and gold rods were evaluated as possible materials for use in the intermediate temperature (200-400 °C) acidic water electrolysers. The corrosion resistance was measured under simulated conditions (molten KH2PO4) corresponding to the proton-conducting solid acids or transition metal phosphates as electrolytes. It was shown that, unlike at temperatures below 200 °C, gold is unstable with respect to corrosion in molten KH2PO4. Platinum demonstrated high corrosion resistance and the anodic and cathodic limits were for the first time found for the electrolyte. Nickel, niobium, Inconel®625, Hastelloy®C-276 and Ta-coated stainless steel (AISI 316L) demonstrated high corrosion stability and can be recommended as construction materials for bipolar plates.

Would CoCr Rods Provide Better Correctional Forces Than Stainless Steel or Titanium for Rigid Scoliosis Curves?

Comparative in vitro, biomechanical study. Compare the effect of rod curvature and material properties on rod flattening and correctional forces. Traditional methods of correction for large progressive deformities involve 3-dimensional correction, performed with an attempt to reach a balanced correction in all planes, spinal instrumentation, and fusion. Increasing attention to the transverse plane correction has developed after the introduction of segmental pedicle screws into the treatment of idiopathic scoliosis. Approximation of the spine (pedicle screws or hooks) to the rods remains the heart of many deformity procedures. Therefore, it is crucial that the instrumentation used provide and maintain the initial correction of the spinal deformity while minimizing potential intraoperative failures. Two experiments were performed using 80 rods made from 4 different materials namely: stainless steel (SS), titanium (Ti), cobalt chromium (CoCr), and ultrahigh strength stainless steel (UHSS). Half of the rods were contoured to 20 degrees, whereas the reaming contoured to 30 degrees. Half of the rods were approximated to a synthetic spine models to measure the flattening of the rods when approximated to highly rigid spine. The other half was used to measure the correctional forces produced by each rod type and curvature. For the 20-degree pre-bend rods, Ti was the best in maintaining its original shape followed by UHSS, SS, and CoCr of 90%, 77%, 62.5%, and 54.4%, respectively. The 30-degree pre-bend showed exactly a similar trend with 80.7% for Ti, 71% for UHSS, 54.6% for SS, and 48.1% for the CoCr rods. For 30-degree pre-bend CoCr and UHSS rods, the intraoperative reduction forces were almost 42% and 10% higher than the Ti and SS rods, respectively. The correctional force produced by the Ti 30-degree pre-bend rod was approximately 67% that of a CoCr and UHSS rods. CoCr and UHSS rods have the ability to produce the highest correction forces, however, both can plastically deform in a very rigid curves. Therefore, it is critical to have sense of the quality of the bone fixation as well as the curve flexibility when selecting for appropriate rod size material and contouring the rod to the desired shape.

First Report of Alternaria alternata Causing Postharvest Black Spot of Fresh Date Palm Fruit in Spain.

Commercial production of date palm fruit (Phoenix dactylifera L.) for fresh consumption has increased in the grove of Elx (Alacant Province, southeast Spain) after the successful development of tissue culture technologies and induced ripening and cold storage protocols. In a survey of losses after harvest, disease symptoms consisting of superficial, small, and firm black spots irregularly distributed throughout the fruit skin were observed in commercially handled and cold-stored fruit. At room temperature, superficial lesions expanded and produced dark mycelium. The potential causal agent was transferred to potato dextrose agar (PDA), incubated at 25°C in darkness, and subcultured on PDA. The identification was performed at the Spanish Type Culture Collection (CECT, University of Valencia, Spain) using colony morphology on PDA and malt extract agar at 26 or 37°C. At 26°C, the fungus rapidly produced cottony white mycelium that turned olivaceous and dark brown to black. Conidiophores were simple, straight or bent, with plain walls. Conidia were brown, obpyriform to ellipsoid (average 22 to 39 × 8 to 15 μm; n = 50), with both transversal and longitudinal septa, often observed in branched chains with more than 5 conidia. Growth occurred at 37°C. The identification of Alternaria alternata (Fr.:Fr.) Keissler was confirmed by the amplification and subsequent sequencing with the primers NL1 and NL4 of the region D1/D2 in the 5' end of the 28S rRNA gene of the isolate IVIA DAA-4 (GenBank Accession No. JX987100). A BLAST search showed 100% identity with A. alternata strain DAOM 216376 (JN938894). Selected healthy 'Medjool' dates were surface disinfected by dipping them for 2 min in a 0.5% sodium hypochlorite solution and thoroughly rinsed with fresh water. To fulfill Koch's postulates, 20 μl of a spore suspension at 1 × 105 spores per ml prepared from 7-day-old colonies grown on PDA were placed in fresh skin wounds made in disinfected fruit using a sterile stainless steel rod with a probe tip 1 mm wide and 2 mm in length (one wound per fruit; three humid chambers with nine fruits each). Wounded but not inoculated fruit were used as controls (one humid chamber with nine fruit). While disease symptoms were observed on all fruit inoculated with A. alternata (average black spots of 3, 6, and 12 mm after 4, 7, and 10 days of incubation at 20°C), no decay was observed on any of the control fruit. Reisolation of the fungus was performed from 10 infected dates and it was positive in all cases. A. alternata has been reported to cause date palm fruit disease in Israel (1) and Egypt (2), whereas Alternaria spp. have been cited in California (3) and Iran (4). To our knowledge, this is the first report of A. alternata causing date palm fruit rot in Spain.

Induced-Charge Electroosmosis Around Touching Metal Rods

Induced-charge electroosmosis (ICEO) around multiple gold-coated stainless steel rods under different ac electric fields is analyzed using microparticle image velocimetry (micro-PIV) and numerical simulations. In the present investigation, the induced electric double layer (EDL) is in weakly nonlinear limit. The ICEO flow around multiple touching rods exhibits geometry dependent quadrupolar flow structures with four vortices. The velocity magnitude is proportional to the square of the electric field. The ICEO flow velocity also depends on the cylinder orientation. The velocity increases with increased radial distance from the rod’s surface, attains a maximum, and then decays to zero. Experimental and numerical velocity distributions have the same trend beyond 0.2 mm of the rod’s surface.

Acute Complications Associated With Removal of Flexible Intramedullary Femoral Rods Placed for Pediatric Femoral Shaft Fractures

The American Academy of Orthopaedic Surgeons position statement on the treatment of pediatric femoral shaft fractures could not comment on the safety of flexible intramedullary (IM) rod removal because of a lack of published evidence. This study reviews the acute complications of flexible IM rod removal from pediatric patients treated for femoral shaft fractures. A retrospective clinical and radiographic analysis at a single institution over a 5-year period. Demographic and radiographic parameters were analyzed to determine their influence on intraoperative and immediate postoperative complications. One hundred sixty-three subjects (133 males, 30 females), mean age of 9.3±2.8 years (range, 2.7 to 14.8 y) and mean weight of 34.4±15.3 kg (range, 14.0 to 139.0 kg), underwent femoral flexible IM rod removal a mean 12.4±10.8 months (range, 2.4 to 63.8 mo) after placement with mean operative time of 51.1±22.3 minutes (range, 10 to 131 min). One hundred fifty-one subjects (92.6%) had stainless-steel Ender rods and the remaining nails were titanium. There were no significant demographic, intraoperative, or radiographic differences comparing subjects with Ender versus titanium rods. Indications for rod removal were pain at insertion site, family request, or surgeon's recommendation. There were 4 (2.5%) minor intraoperative difficulties, including the inability to remove 1 of 2 rods secondary to IM migration (n=1) and complete bone overgrowth at insertion site resulting in prolonged extraction time (n=3). Three of the 4 subjects had the rods placed >60 months before removal. Immediately postoperative (n=134), there were 4 (3.0%) complications, including superficial wound infection (n=3, 2.2%) and knee contracture (n=1, 0.8%). Subjects were released to full activities at a mean 4.7±1.8 weeks postoperatively with no known postoperative fractures. The rate of intraoperative and immediate postoperative complications is low. Neither patient demographics, fracture characteristics, nor operative technique influenced the complication rate. Intraoperative difficulties may be minimized with removal of rods before signs of overgrowth. Level IV, intervention case series.

Experimental Studies of Rod Impact on Bare/Uncovered PBX 9501 Explosive

We present an experimental investigation of the dynamics of rod impact on bare or uncovered PBX 9501 explosive. By weight, PBX 9501 contains 95% octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, commonly known as HMX. The plastic binder is Estane combined with a nitro-plasticizer made of bis(2,2-dinitropropyl)acetal and bis(2,2-dinitropropyl)formal. Experiments were conducted using our single stage gas-gun, allowing us to get very repeatable impact velocities. A stainless steel rod attached to the front of the projectile impacted the explosive target. Impact occurred while the projectile was still in the barrel, allowing for accurate centering of the rod on the target. Seven channels of Photonic Doppler Velocimetry (PDV) were used to measure shock waveprofiles after transmission through the explosive. Velocimetry measurement points were located at different radii from the center of the rod, allowing us to capture the 2-D characteristics of the flow. Also, multiple sets or sequences of experiments were performed. Each set of experiments used a constant rod diameter, impact velocity and PDV probe locations: the thing that was varied from experiment to experiment was the thickness of the PBX 9501 explosive sample. In this way, we built up a detailed experimental record of the impact and reaction dynamics. All experiments discussed used a rod impact velocity near 0.744km/s resulting in an impact stress of ~ 4.5GPa. One series of experiments with 17mm diameter rods resulted in initiation with onset of detonation between 6 and 8mm into the explosive. Another series of experiments with 8.5mm diameter rods resulted in failure to detonate, reactions being quenched by rarefaction waves emanating from the edge of the rod.

Vibration Measurement of a Mechanical Element in Liquid Hydrogen Using an FBG Sensor

A vibration measurement of a mechanical element in liquid hydrogen was conducted using a fiber Bragg grating (FBG) sensor. The monitored mechanical element was an 8-mm diameter stainless-steel rod connected to a bearing cartridge of a ball-bearing, which is an element of a liquid rocket engine. The rotation of the ball-bearing vibrates both the cartridge and the rod to be monitored. The vibration was measured during a rotational test where the test temperature and the maximum rotational speed were 26 K and 30,000 rpm, respectively. The FBG-sensor signals were recorded at the sampling frequency of 50 kHz. The vibration of the rod was measured successfully up to 25 kHz despite the root-mean-square level of the dynamic strain smaller than 10x10-6. The frequency analysis revealed that the FBG-sensor signal corresponded well with the rotational speed of the ball bearing. The peak frequency agreed with the first-order frequency of the rotational speed of the ball-bearing. The experiment demonstrates that FBG sensors are available to mechanical measurements of liquid rocket engines during operational tests, and also seem to be useful for mechanical measurements of fuel cell cars and hydrogen engine cars.

Two self‐referencing methods for the measurement of beam spot position

Two quantitative methods of measuring electron beam spot position with respect to the collimator axis of rotation (CAOR) are described. Method 1 uses a cylindrical ion chamber (IC) mounted on a jig corotational with the collimator making the relationship among the chamber, jaws, and CAOR fixed and independent of collimator angle. A jaw parallel to the IC axis is set to zero and the IC position adjusted so that the IC signal is approximately 50% of the open field value, providing a large dose gradient in the region of the IC. The cGy∕MU value is measured as a function of collimator rotation, e.g., every 30°. If the beam spot does not lie on the CAOR, the signal from the ion chamber will vary with collimator rotation. Based on a measured spatial sensitivity, the distance of the beam spot from the CAOR can be calculated from the IC signal variation with rotation. The 2nd method is image based. Two stainless steel rods, 3 mm in diameter, are mounted to a jig attached to the Linac collimator. The rods, offset from the CAOR, lay in different planes normal to the CAOR, one at 158 cm SSD and the other at 70 cm SSD. As the collimator rotates the rods move tangent along an envelope circle, the centers of which are on the CAOR in their respective planes. Three images, each at a different collimator rotation, containing the shadows of both rods, are acquired on the Linac EPID. At each angle the shadow of the rods on the EPID defines lines tangent to the projection of the envelope circles. From these the authors determine the projected centers of the two circles at different heights. From the distance of these two points using the two heights and the source to EPID distance, the authors calculate the distance of the beam spot from the CAOR. Measurements with all two techniques were performed on an Elekta Linac. Measurements were performed with the beam spot in nominal clinical position and in a deliberately offset position. Measurements were also performed using the Flexmap image registration∕ball-bearing test. Within their uncertainties, both methods report the same beam spot displacement. In clinical use, a total of 203 monthly beam spot measurements on 14 different beams showed an average displacement of 0.11 mm (σ = 0.07 mm) in-plane and 0.10 mm (σ = 0.07 mm) cross-plane with maximum displacement of 0.37 mm in-plane and 0.34 mm cross-plane. The methods described provide a quantitative measure of beam spot position, are easy to use, and provide another tool for Linac setup and quality assurance. Fundamental to the techniques is that they are self-referencing-i.e., they do not require the user to independently define the CAOR.

Dorsal root ganglion compression as an animal model of sciatica and low back pain

As sciatica and low back pain are among the most common medical complaints, many studies have duplicated these conditions in animals. Chronic compression of the dorsal root ganglion (CCD) is one of these models. The surgery is simple: after exposing the L4/L5 intervertebral foramina, stainless steel rods are implanted unilaterally, one rod for each vertebra, to chronically compress the lumbar dorsal root ganglion (DRG). Then, CCD can be used to simulate the clinical conditions caused by stenosis, such as a laterally herniated disc or foraminal stenosis. As the intraforaminal implantation of a rod results in neuronal somal hyperexcitability and spontaneous action potentials associated with hyperalgesia, spontaneous pain, and mechanical allodynia, CCD provides an animal model that mimics radicular pain in humans. This review concerns the mechanisms of neuronal hyperexcitability, focusing on various patterns of spontaneous discharge including one possible pain signal for mechanical allodynia - evoked bursting. Also, new data regarding its significant property of maintaining peripheral input are also discussed. Investigations using this animal model will enhance our understanding of the neural mechanisms for low back pain and sciatica. Furthermore, the peripheral location of the DRG facilitates its use as a locus for controlling pain with minimal central effects, in the hope of ultimately uncovering analgesics that block neuropathic pain without influencing physiological pain.

Micro-PIV measurements of induced-charge electro-osmosis around a metal rod

A cylindrical gold-coated stainless steel rod was positioned at the center of a straight microchannel connecting two fluid reservoirs on either end. The microchannel was filled with 1 mM KCl containing 0.5 μm diameter carboxylate-modified spherical particles. Induced-charge electro-osmotic (ICEO) flow occurred around the metallic rod under a sinusoidal AC electric field applied using two platinum electrodes. The ICEO flows around the metallic rod were measured using micro particle image velocimetry (micro-PIV) technique as functions of the AC electric field strength and frequency. The present study provides experimental data about ICEO flow in the weakly nonlinear limit of thin double layers, in which, the charging dynamics of the double layer cannot be presented analytically. The measured ICEO flow pattern qualitatively agrees with the theoretical results obtained by Squires and Bazant (J Fluid Mech 509:217–252, 2004). Flow around the rod is quadrupolar, driving liquid towards the rod along the electric field and forcing it away from the rod in the direction perpendicular to the imposed electric field. The measured ICEO flow velocity is proportional to the square of the electric field strength, and depends on the applied AC frequency.

Basic Study of Properties of Planate Acoustic Lens Constructed with Phononic Crystal Structure

We developed a planate acoustic lens with a phononic crystal structure for acoustic imaging technology in ocean. To determine the properties of the planate acoustic lens, we simulated the sound field converged by the lens using a finite difference time domain (FDTD) method. In addition, we manufactured a prototype of the planate acoustic lens using stainless-steel rods. In this study, we performed a small-scale trial to reduce the scale to one-tenth the original size of the lens. We measured the sound field converged by the manufactured prototype lens in a water tank. A burst pulse with a frequency of 740 kHz radiated from a transducer. Measurement results agree well with analysis results. The focal distances of measurement and analysis were 12.5 and 11.7 mm, respectively. The measured -3 dB beam width at 3.1 mm almost agrees with the analysis result at 2.3 mm.

Multivariate Analysis of Factors Associated With Kyphosis Maintenance in Adolescent Idiopathic Scoliosis

Multicenter retrospective cohort study of 269 patients. The purpose of this study is to evaluate the surgical and radiographical factors in adolescent idiopathic scoliosis (AIS) surgery that significantly affect kyphosis maintenance. Decreased kyphosis in the thoracic spine is a component of the 3-dimensional deformity in AIS. Suboptimal sagittal alignment after spinal fusion has been identified as a possible cause of lumbar and cervical spinal degeneration and junctional malalignment. Segmental spinal instrumentation continues to evolve, and although excellent coronal plane correction is readily achieved, sagittal plane thoracic hypokyphosis may be seen postoperatively. A retrospective analysis of prospectively collected data from a multicenter AIS database was performed to evaluate factors associated with kyphosis maintenance. A total of 526 patients were enrolled in the database and had a mean thoracic kyphosis (T5-T12) of 22°. In total, 269 patients were identified who had kyphosis of less than 22° and thus comprised the group to be included in this analysis. A complete radiographical series was obtained for each patient preoperatively, immediately postoperatively, and at 2 years postoperatively. All operative data, including the number of levels fused and implant type and density, were also recorded. Multivariate and regression analysis were performed. Eight variables were found to be significantly correlated with kyphosis maintenance at 2 years postoperatively. Anterior approach (r = 0.37, P < 0.001), increased thoracic coronal curve (r = 0.20, P = 0.001), and a greater percentage of hooks in the construct (r = 0.18, P = 0.034) were associated with increased kyphosis at follow-up. A greater number of levels fused (r = -0.33, P < 0.001), preoperative kyphosis (r = -0.39, P < 0.001), percentage of screws in the construct (r = -0.18, P = 0.03), using standard stainless steel rods (r = -0.47, P = 0.011), and percent decrease in thoracic curve (r = -0.23, P < 0.001) all were correlated with hypokyphosis at follow-up. Our multivariate analysis demonstrates that in patients with AIS who have thoracic hypokyphosis as part of their deformity, certain factors must be taken into account in the preoperative planning to prevent hypokyphosis after surgical correction.

Factors associated with patency of the uterine cervix in bitches with pyometra

This study examined factors involved in the patency of uterine cervices in the bitch with pyometra. The uterine cervices were obtained from the bitches with pyometra at the time of ovariohysterectomy. Cervical patency was measured by inserting the stainless steel rods with different diameter into cervical canals. Collagen concentration and collagenase activity (for type I collagen) in the tissue were determined and the number of neutrophils, which contain the enzymes related to collagen metabolism, and morphological changes in collagenous fibers were studied by histological examination. Levels of mRNA expressions for hormonal factors, estrogen receptor-α (ER-α), progesterone receptor (PR), relaxin (Rlx) and an attractant of neutrophils, interleukin-8 (IL-8), were determined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). In the statistical analysis, the cervical patency positively correlated with the collagenase activity, and negative correlation was found between the cervical patency and collagen concentration. Histological examination indicated distinct positive correlation between the cervical patency and the number of neutrophils in the cervical stroma and that the collagenous fiber in the uterine cervix became thinner and degraded with increase of the cervical patency. Although there was no relationship between the cervical patency and the level of mRNA for ER-α, PR or Rlx, IL-8 mRNA level has significant positive correlation with the cervical patency and the number of neutrophils in the cervical stroma.These results suggest that the increased number of neutrophils in the uterine cervix, which could be related to the local expression of IL-8, may be involved in collagen degradation and connective tissue remodeling to increase cervical patency in the bitch with pyometra.

A Novel Method for Measuring Catheter Lock Spillage: An In Vitro Study

Catheters are widely used for blood purification, parenteral nutrition, and for the infusion of drugs. Previous work on catheter lock spillage has focused on the theory and in vitro demonstration of catheter lock spillage caused by the laminar flow profile and by fluid exchange caused by density differences. This work describes an in vitro test with a method that potentially allows measurement of catheter lock spillage in vivo without sampling. The method is based on the change of the electrical resistance of the catheter when the lock solution is injected. This method was tested in vitro with human blood at 36°C using 46.7% trisodium citrate as catheter lock solution. The catheter tip was placed in a beaker filled with whole blood. A stainless steel rod in the beaker served as one electrode and an Arrow-Johans ECG adapter, which was placed on the distal end of the catheter, served as a second electrode. Conductivity was measured with a 5V (rms) 310 Hz sinus voltage and a 10 kOhm resistor in series to the catheter. The driving voltage and the voltage drop at the catheter was continuously measured with a program written under LabView (National Instruments), and the results were converted into mean trisodium citrate concentrations. Within 20 min, the mean trisodium citrate concentration in the catheter decreased to less than 5%. Unlike the previous methods used for catheter lock spillage measurement, this principle can be employed to measure the time course of catheter lock spillage in vivo.

An Electropolymerized Pyrrole‐based Coating for Stir Bar Sorptive Extraction of Btex from Water Followed by Gas Chromatography‐Mass Spectrometry

AbstractA stir bar sorptive extraction (SBSE) technique was developed by the use of polypyrrole (PPy) sorbent, electropolymerized on the surface of a rod, as a possible alternative to solid‐phase microextraction (SPME). Liquid desorption was subsequently employed to transfer the extracted analytes into the injection port of a gas chromatography‐mass spectrometry (GC‐MS). The PPy sorbent including polypyrrole‐dodecyl sulfate (PPy‐DS) was deposited on the surface of a stainless steel rod from the corresponding aqueous electrolyte by applying a constant deposition potential. The developed method was applied to the trace level extraction of BTEX (benzene, toluene, ethylbenzene, o,p‐xylene) from aqueous sample. Optimization of influential experimental conditions including the voltage of power supply, the time of PPy electrodeposition, the extraction temperature, the ionic strength and the extraction time were also investigated. The detection limits of the method under optimized conditions were in the range of 0.01–0.1 ng·mL−1. The relative standard deviations (RSD) at a concentration level of 1 ng·mL−1 were obtained between 8% and 13% (n=6). The calibration curves of BTEX showed linearity in the range of 0.03 to 600 ng·mL−1. The proposed method was successfully applied to the extraction of some selected BTEX from river water samples and the relative recoveries were higher than 90% for all the analytes.

Ultra High Resolution Linear Ion Trap Orbitrap Mass Spectrometer (Orbitrap Elite) Facilitates Top Down LC MS/MS and Versatile Peptide Fragmentation Modes

Although only a few years old, the combination of a linear ion trap with an Orbitrap analyzer has become one of the standard mass spectrometers to characterize proteins and proteomes. Here we describe a novel version of this instrument family, the Orbitrap Elite, which is improved in three main areas. The ion transfer optics has an ion path that blocks the line of sight to achieve more robust operation. The tandem MS acquisition speed of the dual cell linear ion trap now exceeds 12 Hz. Most importantly, the resolving power of the Orbitrap analyzer has been increased twofold for the same transient length by employing a compact, high-field Orbitrap analyzer that almost doubles the observed frequencies. An enhanced Fourier Transform algorithm—incorporating phase information—further doubles the resolving power to 240,000 at m/z 400 for a 768 ms transient. For top-down experiments, we combine a survey scan with a selected ion monitoring scan of the charge state of the protein to be fragmented and with several HCD microscans. Despite the 120,000 resolving power for SIM and HCD scans, the total cycle time is within several seconds and therefore suitable for liquid chromatography tandem MS. For bottom-up proteomics, we combined survey scans at 240,000 resolving power with data-dependent collision-induced dissociation of the 20 most abundant precursors in a total cycle time of 2.5 s—increasing protein identifications in complex mixtures by about 30%. The speed of the Orbitrap Elite furthermore allows scan modes in which complementary dissociation mechanisms are routinely obtained of all fragmented peptides.

The “Shadow Sign”

Stainless steel spinal instrumentation has been supplanted in recent years by titanium instrumentation. Knowing whether stainless steel or titanium was used in a previous surgery can guide clinical decision making processes, but frequently the clinician has no way to know what type of metal was used. We describe the radiographic "shadow sign," in which superimposed titanium rods and screws remain radiolucent enough that the contour of the underlying components can be seen on a lateral radiograph, whereas superimposed stainless steel rods and screws are completely radiopaque. This technique was evaluated using a retrospective, randomized, and blinded radiographic comparison of titanium and stainless steel spinal instrumentation. The objective was to determine whether the "shadow sign" can reliably differentiate titanium from stainless steel spinal instrumentation. Lateral radiographs from 16 cases of posterior spinal instrumentation (6 titanium, 6 stainless steel, and 2 replicates of each to assess intraobserver reliability) were randomly selected from a database of cases performed for pediatric scoliosis in a university setting from 2005 to 2009. The cases were randomized then shown to 19 orthopaedic surgery residents, 1 spine fellow, and 2 spine attendings. After the "shadow sign" was described, the surgeons were asked to determine what type of metal each implant was made of. The κ value for both stainless steel and titanium versus the gold standard was 0.83 [standard error (SE) = 0.053], indicating excellent agreement. The κ value for agreement between raters was 0.71 (SE = 0.016) and the κ value for agreement within raters was 0.70 (SE = 0.016), both of which indicated substantial agreement. The "shadow sign" can help a clinician differentiate titanium from stainless steel spinal instrumentation based on radiographic appearance alone. Furthermore, our study reveals that the level of experience in diagnosing spinal lateral radiographs also enhances the use of the "shadow sign" indicator. The method proposed to differentiate titanium from stainless steel falls within the diagnostic studies domain. As unaltered randomization was used to enroll radiographs and the procedure was systematic, this study may be classified in the Level II category.

Production of a Periodic Plasma Structure for Basic Experiments on Plasma Photonic Crystals in Microwave Range

A 2-D periodic plasma structure is produced by a low-pressure direct-current argon discharge for basic experiments on plasma photonic crystals in the microwave range of a few gigahertz. A cathode consisting of 7 × 11 stainless steel rods located at 3-cm intervals, which are covered by an insulator, and a grounded anode are set in a vacuum chamber. An axial profile of a plasma density measured by a Langmuir probe shows the production of the periodic plasma structure with the same intervals as the electrode. The highest and lowest plasma densities are about 1.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> and 0.9 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , respectively. The image of the discharge suggests the production of a "2-D" periodic structure composed of plasma columns.