Stainless Steel Loop Research Articles

Helium circulation cooling experiment for a 3T NbTi superconducting magnet

This paper proposes an experimental investigation to validate the use of helium as the sole coolant in a pipe circulation cooling mode for a small 3 T NbTi superconducting magnet. Injecting helium into pipes and liquefying the magnet at 4.2 K will also be explored, utilizing the evaporation of small amounts of liquid helium within the pipes to cool the NbTi magnet and calculate its liquefaction volume and cooling time. Firstly, we investigated a novel approach to achieve acceptable temperatures for current leads by augmenting the top mass and increasing the length of the leads. Additionally, stainless steel (SS) loop tubes surrounding the magnet were designed in a new way to enhance convective heat exchange. Finally, various heat conduction devices were added and after successfully cooling all parts of the experimental apparatus, the heat transfer formula will be used to calculate the theoretical cooling time of pulsed supplementary helium gas, which will then be compared and discussed with actual experimental time. The cryogenic experiment shows that less liquid helium without any other coolants can be adopted efficiently to cool LTS magnets by SS pipelines. Consequently, this approach is significant to reducing consumption of coolant for cooling the LTS NbTi magnet to 4.2 K.

Loop electrosurgical excision procedure: A Review

LEEP is a one-of-a-kind outpatient procedure for diagnosing and treating dysplastic cervical lesions. Loop diathermy treatment, loop excision of the transformation zone (LETZ), and large loop excision of the transformation zone (LLETZ) are other names. This approach yields high-quality cytologic specimens and has no negative effects on reproductive function. It also can be used to treat cervical cancer by replacing cryotherapy or laser. LEEP can be used to bypass the entire transformation zone. This is done with the help of a high-frequency, low-current electric generator and a stainless-steel loop. The LEEP procedure has a similar complication rate to cryotherapy. Bleeding is the most common complication. In addition, there may be inadequate lesion removal and cervical stenosis. LEEP has several advantages over other treatments, including removing aberrant tissue that allows cytologic examination, cheap cost, simplicity of acquiring important skills, and the potential to treat lesions with fewer visits. Patients are pleased with the surgery. LEEP is anticipated to be widely used by family physicians.

Differential adsorption of analyte and deuterated analogue onto the rotor seal of the injector in high-performance liquid chromatography/electrospray ionisation mass spectrometry.

Samples were injected onto the HPLC system via either a Valco C14W.1 internal sample injector or a Rheodyne 7125 injector, both with dissimilar Vespel rotor seals, and linked to a quadrupole time-of-flight (QTOF) mass spectrometer. Alternatively, samples were infused directly into the mass spectrometer via a syringe-driver. Electrospray ionisation in positive mode was used in both cases. Experiments demonstrated significant differential adsorption of the analyte (RAC inhibitor, NSC23766) and its tri-deuterated internal standard onto the Vespel rotor seal, with the latter seeming to be preferentially adsorbed. The deuterated analogue also showed lower electrospray sensitivity, as demonstrated by syringe infusion of a mixture of the compounds, compared with their separate infusion at the same concentration. This study has demonstrated the problem of differential adsorption onto HPLC Vespel rotor seals, and that the use of a stable-isotope-labelled analogue as internal standard does not guarantee the constancy of the analyte/internal response ratio in quantitative methods. The partial solution was to work at much higher concentration where adsorption, whilst still apparent, was relatively insignificant.

Degradation of chloramphenicol by chlorine and chlorine dioxide in a pilot-scale water distribution system

This paper presents the degradation of chloramphenicol (CAP) by chlorine and chlorine dioxide (ClO2) in tap water in a pilot-scale water distribution system (WDS) containing loops of three different pipe materials (stainless steel, ductile iron, and polyethylene). Greater degradation of CAP was seen with chlorine than with chlorine dioxide. After 180 min in the ductile iron loop of the WDS, the percent degradation of CAP by 2.0 mg/L of chlorine or ClO2 was 76% and 52%, respectively. The degradation of CAP by chlorine in the WDS was investigated under various conditions, including chlorine concentrations of 1.0–4.0 mg/L, and varying pipe materials, flow velocity, and temperature. Degradation of CAP under different conditions could be fitted by first-order kinetics, and the determined first-order rate constants (k, min−1) increased with an increase in chlorine concentration, flow velocity, and temperature. The degradation of CAP in different pipes followed the order stainless steel loop > ductile iron loop > polyethylene loop. Identified oxidized products of the chlorination of CAP were in agreement with proposed reaction pathways, which were also theoretically confirmed by quantum chemical calculations. Formation of three disinfection byproducts (chloroform, bromodichloromethane, and dibromochloromethane) was observed, with increases of 7.7, 0.76, and 0.39 µg/L, respectively, after 160 min.

Chloramines in a pilot-scale water distribution system: Transformation of 17β-estradiol and formation of disinfection byproducts

The degradation and transformation products of 17β-estradiol (E2) by chloramines in a pilot-scale water distribution system (WDS) were investigated using varying conditions including multiple mass ratios of chlorine to nitrogen (Cl/N), changing concentrations of chloramines, and different pH and pipe materials. The degradation of E2 was complete in ≤9 h in both deionized water (DW) and in the WDS under studied conditions. When the degradation rate of E2 was compared in WDS and DW, the degradation rate was appreciably greater in the WDS than in the DW at Cl/N mass ratios of 3, 4 and 6. However, at Cl/N mass ratios of 8 and 9, degradation was faster in the DW than in the WDS. The degradation rate of E2 was greatly affected by the initial total chloramine concentration, and the degradation of E2 in DW was consistent with second-order kinetics. The degradation rate of E2 in both the DW and the WDS increased with increasing pH. The order of degradation rate of E2in different pipes was: ductile iron loop (loop A) > polyethylene (PE) loop (loop B)> stainless steel loop (loop C). Ten specific degradation products of E2, produced by chloramination, were identified. Most of the degradation products of E2 chloramination were stable for more than 10 h. The degradation pathways of E2 in the WDS are proposed and briefly discussed. The concentrations of trihalomethanes (THMs), haloacetic acids (HAAs), and halogenated nitromethane (HNMs) during the degradation E2 in WDS were also determined.

P.4.f.001 The cumulative effect of childhood trauma on adult mental and physical health: results from the Marine Resiliency Study

In this work, we interestingly happened to observe the adsorption of stainless steel sample loop of HPLC. The adsorptive behaviors of the stainless steel loop toward different kinds of compounds were studied, including polycyclic aromatic hydrocarbons (PAHs), halogeno benzenes, aniline derivatives, benzoic acid derivatives, phenols, benzoic acid ethyl ester, benzaldehyde, 1-phenyl-ethanone and phenethyl alcohol. The adsorptive mechanism was probably related to hydrophobic interaction, electron-rich element–metal interaction and hydrogen bond. Universal adsorption of stainless steels was also testified. Inspired by its strong adsorptive capability, bare stainless steel loop was developed as a modification-free in-tube device for solid-phase microextraction (SPME), which served as both the substrate and sorbent and possessed ultra-high strength and stability. Great extraction efficiency toward PAHs was obtained by stainless steel loop without any modification, with enrichment factors of 651–834. By connecting the stainless steel loop onto a six-port valve, an online SPME–HPLC system was set up and an SPME–HPLC method has been validated for determination of PAHs. The method has exceptionally low limits of detection of 0.2–2 pg/mL, which is significantly lower than that of reported methods with different kinds of sorbents. Wide linear range (0.5–500 and 2–1000 pg/mL), good linearity (R2 ≥ 0.9987) and good reproducibility (RSD ≤ 2.9%) were also obtained. The proposed method has been applied to determine PAHs in environmental samples. Good recoveries were obtained, ranging from 88.5% to 93.8%.

Adsorptive behavior and solid-phase microextraction of bare stainless steel sample loop in high performance liquid chromatography

In this work, we interestingly happened to observe the adsorption of stainless steel sample loop of HPLC. The adsorptive behaviors of the stainless steel loop toward different kinds of compounds were studied, including polycyclic aromatic hydrocarbons (PAHs), halogeno benzenes, aniline derivatives, benzoic acid derivatives, phenols, benzoic acid ethyl ester, benzaldehyde, 1-phenyl-ethanone and phenethyl alcohol. The adsorptive mechanism was probably related to hydrophobic interaction, electron-rich element–metal interaction and hydrogen bond. Universal adsorption of stainless steels was also testified. Inspired by its strong adsorptive capability, bare stainless steel loop was developed as a modification-free in-tube device for solid-phase microextraction (SPME), which served as both the substrate and sorbent and possessed ultra-high strength and stability. Great extraction efficiency toward PAHs was obtained by stainless steel loop without any modification, with enrichment factors of 651–834. By connecting the stainless steel loop onto a six-port valve, an online SPME–HPLC system was set up and an SPME–HPLC method has been validated for determination of PAHs. The method has exceptionally low limits of detection of 0.2–2pg/mL, which is significantly lower than that of reported methods with different kinds of sorbents. Wide linear range (0.5–500 and 2–1000pg/mL), good linearity (R2≥0.9987) and good reproducibility (RSD≤2.9%) were also obtained. The proposed method has been applied to determine PAHs in environmental samples. Good recoveries were obtained, ranging from 88.5% to 93.8%.

Effect of non-condensable gas on startup of a loop thermosyphon

Non-condensable gas (NCG) generated inside two-phase heat transfer devices can adversely affect the thermal performance and limit the lifetime of such devices. In this work, experimental investigation of the effect of NCG on the startup of an ammonia–stainless steel loop thermosyphon was conducted. In the experiment, nitrogen was injected into the loop thermosyphon as NCG. The effect of NCG inventory on the startup behavior was investigated by adjusting the injected amount of nitrogen. The experimental results reveal that NCG prolongs the startup time and increases the startup liquid superheat and temperature overshoot; the more NCG exists in the loop thermosyphon, the higher the liquid superheat and temperature overshoot. When NCG is present in the system, boiling usually occurs in the evaporator before startup, but it does not mean the system will start up instantly, which differs from the conditions without NCG. Under all the conditions, increasing the heat load can effectively shorten the startup time but leads to a large temperature overshoot; forced convection cooling of the condenser has almost no effect on shortening the startup time especially for large NCG inventory situations, but it can effectively limit the temperature overshoot. For large NCG inventory situations, the loop thermosyphon can start up at a small heat load (5 W) or even without a heat load when the condenser is cooled by forced convection of ethanol. No failed startups occurred during any of the tests.

Experimental tests of a stainless steel loop heat pipe with flat evaporator

Abstract This paper describes the experimental results showing the thermal characteristics of a loop heat pipe (LHP) with the evaporator in the shape of a flat disk having an active diameter of 50 mm and a thickness of 13 mm. The loop and the wick are made of stainless steel and water is used as working fluid. The system could be used for the thermal control of space application devices, and the goal of the experimental research was to improve and extend the knowledge in this field, adding the results to those obtained with these devices manufactured with different design, architecture and material. Tests carried out at horizontal elevation (orientation), in both configurations, that is with the evaporator below the compensation chamber (favourable) and with the evaporator above the compensation chamber (unfavourable), allow the analysis of the start-up reliability and the operational characteristics of the LHP in a wide range of heat loads. During the testing of the LHP under single step heat load, the thermal response presented by the loop to achieve steady-state is very long implying a long start-up time. With the evaporator above the compensation chamber (unfavourable), thermal and hydraulic oscillations are observed throughout the loop. The effect of these oscillations on the thermal performance of the LHP is not very significant. In the favourable configuration no oscillation occurs and the device is able to transfer a maximum heat load of 75 W with the evaporator temperature below 150 °C. The thermal resistance ( R LHP ) of the LHP, which is the resistance from the evaporator external surface to the condenser external surface (refrigerant water sink), lies between 3.33 and 50.7 °C/W.

Studies of the mechanism of the in-loop synthesis of radiopharmaceuticals

A series of experiments were performed to better understand the mechanism of the In-loop [ 11C]CH 3I-methylation. The timing of [ 11C]CH 3I delivery is critical for the high yield of radiolabeling since in-loop radioactivity trapping is reversible. Trapped radioactivity escapes faster from a Tefzel loop compared to a PEEK- or stainless steel loop. Up to 50% of delivered radioactivity may be concentrated at the loop origin (representing 8.1% of the total loop volume). A five-fold reduction of the reaction solvent volume and/or precursor amount may lead to a decrease of the product radiochemical yield either by lowering the in-loop radioactivity trapping or by diminishing conversion of [ 11C]CH 3I into the product.

Central venous catheter failure is induced by injury and can be prevented by stabilizing the catheter tip

Purpose: Thrombosis associated with central venous catheters is a significant cause of device failure, morbidity, and loss of access sites. We hypothesized that central vein thrombosis is caused by catheter injury to the vein wall and that it can be reduced by stabilizing the catheter tip. To test these hypotheses, we studied central vein catheters in a porcine model. Test catheters had a silicone-encased stainless steel loop at the indwelling end that contacted the vein wall and stabilized the catheter tip in the center of the vessel. Methods: Sealed silicon elastic (Silastic) catheters (3.2 mm outer diameter) with and without a stabilizing loop were inserted via the external jugular vein into the superior vena cava just above the right atrium. Animals were killed at 1, 2, 4, and 8 weeks, and the vena cava was inspected for the presence of thrombus and entrapment of the catheter tip. Results: In control animals mural thrombus developed at the site of the catheter tip. This thrombus organized by invasion of macrophages and smooth muscle cells, eventually forming a lesion similar to intimal hyperplasia. Lesion cross-sectional area was significantly smaller in animals with loop catheters than in control animals at 2 weeks (1.2 ± 1.3 vs 34.5 ± 23.9 mm2; p = 0.05) and 4 weeks (2.8 ± 0.3 vs 13.9 ± 5.8 mm2; p < 0.05). By 8 weeks the vena cava was nearly occluded in most animals and the catheter tip was entrapped in this lesion in all cases. Test catheters eliminated the injury process for up to 8 weeks ( p < 0.01, χ2 control vs loop catheter entrapment). Very little injury response was found where the loop contacted the vein wall, and the catheter tip was free of thrombus in all cases. Conclusions: Mural thrombosis at the tip of indwelling central catheters is caused by chronic mechanical venous wall injury. Vessel injury and the resulting thrombosis can be prevented by a catheter modification that stabilizes the tip. Such a catheter may significantly reduce catheter malfunction and morbidity associated with these devices. (J Vasc Surg 1998;28:59-66.)

Cryogenic sampling for aniline vapor with subsequent liquid chromatography-electrochemical detection analysis

A cryogenic sampler for aniline vapors was evaluated by collecting samples of 10 ppm aniline in air and directly analyzing the collected aniline by liquid chromatography with electrochemical detection. The cryogenic sampler achieved nearly 100% collection and recovery efficiency, with a detection limit of ≈ 4 parts-per-billion (10 9) aniline in air for a sample collected at 10 cm 3/min for 40 s in a 200-μl stainless-steel loop at — 10°C. About 5 min was necessary to dissolve the trapped aniline into 200 μl of a mobile phase desorbing solution at 20°C.

Countermeasures to Microbiofouling in Simulated Ocean Thermal Energy Conversion Heat Exchangers with Surface and Deep Ocean Waters in Hawaii

Countermeasures to biofouling in simulated ocean thermal energy conversion heat exchangers have been studied in single-pass flow systems, using cold deep and warm surface ocean waters off the island of Hawaii. Manual brushing of the loops after free fouling periods removed most of the biofouling material. However, over a 2-year period a tenacious film formed. Daily free passage of sponge rubber balls through the tubing only removed the loose surface biofouling layer and was inadequate as a countermeasure in both titanium and aluminum alloy tubes. Chlorination at 0.05, 0.07, and 0.10 mg liter for 1 h day lowered biofouling rates. Only at 0.10 mg liter was chlorine adequate over a 1-year period to keep film formation and heat transfer resistance from rising above the maximum tolerated values. Lower chlorination regimens led to the buildup of uneven or patchy films which produced increased flow turbulence. The result was lower heat transfer resistance values which did not correlate with the amount of biofouling. Surfaces which were let foul and then treated with intermittent or continuous chlorination at 0.10 mg of chlorine or less per liter were only partially or unevenly cleaned, although heat transfer measurements did not indicate that fact. It took continuous chlorination at 0.25 mg liter to bring the heat transfer resistance to zero and eliminate the fouling layer. Biofouling in deep cold seawater was much slower than in the warm surface waters. Tubing in one stainless-steel loop had a barely detectable fouling layer after 1 year in flow. With aluminum alloys sufficient corrosion and biofouling material accumulated to require that some fouling coutermeasure be used in long-term operation of an ocean thermal energy conversion plant.

Mechanical properties of orthodontic wires in tension, bending, and torsion

The mechanical properties of three sizes of stainless steel (SS), nickel-titanium (NT), and titanium-molybdenum (TM) orthodontic wires were studied in tension, bending, and torsion. The wires (0.016 inch, 0.017 by 0.025 inch, and 0.019 by 0.025 inch) were tested in the as-received condition. Tensile testing and stiffness testing machines along with a torsional instrument were used. Mean values and standard deviations of properties were computed. The data were analyzed statistically by analysis of variance using a factorial design. Means were ranked by a Tukey interval calculated at the 95 percent level of confidence. In tension, the stainless steel wires had the least maximum elastic strain or springback, whereas the titanium-molybdenum wires had the most. Higher values of springback indicate the capacity for an increased range of activation clinically. In bending and torsion, the stainless steel wires had the least stored energy at a fixed moment, whereas the nickel-titanium wires had the most. Spring rates in bending and torsion, however, were highest for stainless steel wires and lowest for nickel-titanium wires. A titanium-molybdenum teardrop closing loop delivered less than one half the force of a comparable stainless steel loop for similar activations.

Carbon Transfer Behavior of Materials for LMFBR's Steam-Generator in Flowing Sodium

Using an AISI 304 stainless steel loop, the effect of exposure to flowing heated sodium was examined on materials considered suitable for LMFBR steam generators. The test specimens were exposed for 1,000 hr at temperatures ranging of 550°~425°C, descending in the direction of sodium flow. The oxygen concentration in the sodium was about 8 ppm. The materials tested were ferritic 2¼Cr-1Mo, 2¼Cr-1Mo-Nb, high Cr-1Mo and austenitic AISI 316 stainless steel. The loss of weight through exposure to liquid sodium was found to depend upon the heat-treatment history in the case of the 2¼Cr-1Mo steels. The principal cause of this loss of weight was confirmed to be decarburization, and differences in the heat-treatment history may possibly influence the decomposition behavior of carbides. Increasing the chromium content in Cr-1Mo steel specimens tended to modify the behavior of the specimen in the direction of increasing carbon concentration near the specimen surface during exposure to liquid sodium, altering the effect of exposure from decarburization to carburization at a chromium content somewhere between 3 and 5%. Thermal aging of annealed 2¼Cr-lMo steel was found to reduce its tensile strength at 500°C to a marked degree.

The Transport of Radioactive Corrosion Products in High-Temperature Water—I. Recirculating loop Experiments

A stainless-steel loop containing recirculating, pressurized water at 300°C and neutral pH has been used to investigate the processes by which surfaces in nuclear reactor coolant circuits can become contaminated by radioactive corrosion products. By measuring deposition rates of activity onto metals (usually stainless steel) under different conditions and by examining exposed surfaces, it was deduced that the corrosion of the test surface controls the activation. Hence, the traditional phenomenological method of describing activation by first-order deposition and release coefficients is an oversimplification.

The Measurement of the Lattice Parameters of a Gas Cooled Reactor Lattice

A series of experimental measurements has been made on the Experimental Gas Cooled Reactor (EGCR) lattice in the Physical Constants Test Reactor (PCTR). The measurements provide a broad basis for normalization of reactor calculations for lattices of this type. The fuel assembly is a cluster of seven uranium oxide rods, enriched in the U235 isotope and clad with stainless steel. The fuel is spaced on an eight-inch square pitch in a graphite moderator. Values of the lattice parameters k∞, f, p, and ε have been obtained for 1.8% enrichment of the uranium oxide fuel. The values of k∞ and f have also been obtained for 2.6% enrichment fuel. The techniques of using the PCTR have been extended so that supercell measurements may be made. The values of the strength of a boron carbide control rod and a stainless steel loop tube have been obtained in this way. The strength of such an inhomogeneous poison in the lattice is expressed as the difference in the supercell multiplication factor k∞ with and without the poison in the supercell. This difference is the same quantity which is obtained in the usual reactor cell calculation. The fuel temperature coefficient of for this cluster has also been measured between 50 and 500°C. The coefficient obtained is temperature dependent. The more important of the lattice parameters for the 1.8% enriched fuel are = 1.146 ± 0.004,f = 0.809 ± 0.005, p28 = 0.824 ± 0.006, ε = 1.019 ± 0.002, Δk (control rod -16 cell supercell) = -0.157 ± 0.012, Δk (empty loop tube -9 cell supercell) = -0.117 ± 0.011, and (l/k∞)(dk∞/dT) = -(0.68 ± 0.05) X 10-3T-1/2(oK)-1 For the 2.6% enriched fuel, results are k∞ = 1.256 ± 0.009 and f = 0.845 ± 0.006.

JRR-1一次冷却水中の微量放射性核種の定量

A sample of primary cooling water taken from the stainless steel loop facility of JRR-1 on May 9, 1959, had gamma activities of about 10-4μc/ml.The gamma spectrum of the sample showed peaks at 0.32, 0.51, 0.83, 1.1 and 1.3 MeV. The separation of radionuclides was done as follows: The sample solution was dried, dissolved with 11.4N hydrochloric acid, and transferred to a Dowex 1 (H type) anion exchange resin column bed (∅ 1cm, h 10cm, 100200 mesh). The nuclides absorbed on the column were successively eluted with acid solutions of decreasing acidities (11.4, 6.0 and 3.0N hydrochroric acid) to separate fractions of nickel, manganese, cobalt and iron.The gamma activties of the frations were measured with a 256 channel pulse hight analyzer. The nuclides were identified by their gamma energie, chemical properties and half-lives, which are given in Table l as well as the probable ways of formation.