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Corrosion fatigue properties of narrow gap laser welded 301L stainless steel
摘要： In this paper, the corrosion-fatigue behavior of 301L stainless steel (SS) welded joints using narrow gap laser wire welding under the different stress ratio and concentrations of Cl? has been investigated. Corrosion fatigue life curve (S-N) under different conditions was tested and fitted to obtain the fatigue limit. The microstructures and fracture surfaces of specimens were examined by optical microscopy (OM) and scanning electron microscopy (SEM). EBSD results have shown that chromium depletion in the weld heat-affected zone (HAZ) contributes to the decrease of corrosion fatigue properties in the HAZ.
关键词： 301L,chromium depletion,corrosion fatigue
更新于2025-09-23 15:23:52
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Insight into the mechanisms for hexavalent chromium reduction and sulfisoxazole degradation catalyzed by graphitic carbon nitride: The Yin and Yang in the photo-assisted processes
摘要： As robust polymeric catalysts, graphitic carbon nitride (g-C3N4) has been known to have great application potential in environmental remediation. However, the mechanisms in the photo-assisted catalytic processes during the reduction or oxidation of pollutants are still difficult to discern and therefore not well studied. In this work, visible-assisted catalytic reduction of hexavalent chromium (Cr(VI)) or oxidation of sulfisoxazole (SIZ) by g-C3N4 with the addition of formic acid (FA) or potassium peroxydisulfate (PS) were systematically investigated. Effects of operation parameters such as g-C3N4 dosage, FA concentration, Cr(VI) concentration, solution pH, PS concentration were studied. The results showed g-C3N4 can be effective and robust catalyst for both the reduction (Yin) and oxidation (Yang) reactions in the environmental remediation. Mechanisms were studied by using electron spin resonance (ESR) spectroscopy. The results revealed the CO2?? is the predominant radical for Cr(VI) reduction in the g-C3N4/FA/Vis system and the SO4?? and ?OH are all the main radicals for the oxidation of SIZ in the g-C3N4/PS/Vis system. The photo-generated carriers by g-C3N4, act as radical initiator, were responsible for the production of the reactive radical species in aqueous solution. This work not only shed a new light on the application of semiconductor polymers for the removal of micropollutants and also will expand the applicability of the polymeric photocatalysts for environmental remediation.
关键词： Micropollutants,Sulfisoxazole,Hexavalent chromium,Mechanisms,Graphitic carbon nitride
更新于2025-09-23 15:23:52
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Influence of Cr doping on Schottky barrier height and visible light detection of ZnO thin films deposited by magnetron sputtering
摘要： A comparative study of the electrical and photodetection properties of ZnO and Cr doped ZnO thin films are being reported here. The films were deposited using magnetron sputtering. X-ray diffraction (XRD) revealed hexagonal crystal structure of the films with (002) preferred orientation. Pt/ZnO/Pt and Pt/Cr doped ZnO/Pt Schottky diodes were fabricated for photodetection studies. The Schottky barrier height was lowered for Cr doped ZnO film as compared to ZnO film. The ideality factor was improved upon Cr doping. Pt/ZnO/Pt diode was unresponsive to visible light, however, Pt/Cr doped ZnO/Pt diode showed response to visible light with short response and recovery times. The response of the Pt/Cr doped ZnO/Pt diodes to visible light is attributed to the reduction in band gap of the Cr doped ZnO thin film.
关键词： Thin films,Schottky contact,Chromium-doped Zinc oxide,Sputtering,Photodetectors
更新于2025-09-23 15:23:52
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Luminescent TOP Nanosensors for Simultaneously Measuring Temperature, Oxygen, and pH at a Single Excitation Wavelength
摘要： Two nanosensors for simultaneous optical measurements of the bioanalytically and biologically relevant analytes temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with a near infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3, CrBPh4) and an inert reference dye (Nile Red, NR or 5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin, TFPP) and are covalently labeled with pH-sensitive fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal spectrally distinguishable emission bands allowing for ratiometric intensity-based and time-resolved studies in the visible and near infrared wavelength region. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of these nanosensors for the sensitive fluorescence readout of TOP simultaneously at the same position.
关键词： lifetime,fluorescence,chromium(III) complex,oxygen/pH/temperature biosensor,optical multianalyte nanosensors,phosphorescence
更新于2025-09-23 15:22:29
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Newly developed chromium-doped fiber as a saturable absorber at 1.55- and 2.0-μm regions for Q-switching pulses generation
摘要： We demonstrate a Q-switching operation laser at 1.55- and 2-μm region using a homemade 10 cm long of Chromium-doped ?ber (CrDF) as a passive saturable absorber (SA). Erbium-doped ?ber (EDF) and Thulium-doped ?ber (TDF) as a gain medium cooperate in the all-?ber ring cavity con?guration. CrDF was fabricated by Modi?ed Chemical Vapour Deposition (MCVD) technique in conjunction with conventional solution doping (SD) method. The CrDF has a saturable absorption of 9% at 1.55-μm region with a saturation intensity of 22 MW/cm2. Therefore, a stable pulse train obtainable within 75–173 mW, with a repetition rate increases from 68.12 kHz to 115.9 kHz. At the maximum pump level, a shorter pulse width, maximum output power, and maximum pulse energy are 3.85 μs, 10.86 mW, and 94.1 nJ, respectively. In TDF laser cavity, the laser pulsing generates from 363 mW to 528 mW, where the repetition rate increases from 13.02 kHz to 27.62 kHz. At maximum pump power, a shorter pulse width, maximum output power, and pulse energy are obtained with 4.48 μs, 6.36 mW, and 230.27 nJ, respectively. Both pulse trains at 1.55- and 2-μm region are stable with a signal-to-noise ratio (SNR) of 71 dB and 44 dB, respectively. These ?ndings are important to the discovery of robust passive saturable absorber development in a form of ?ber which has a similar melting point to the rest of the silica ?ber in the proposed cavities. Thus, it will be a kick-started to alternative form of passive SAs in developing a future high-power ?ber lasers.
关键词： Pulse laser,Ring cavity,Chromium-doped ?ber saturable absorber,Fiber laser
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field-emission of spin-polarized electrons from Cr thin film grown on W{113} surfaces
摘要： Spin polarization of ?eld-emitted electrons from a Cr thin ?lm grown on W{113} facets after annealing at 1000 K was measured at room temperature. The magnitude of spin polarization of 30% was two thirds of that of a Cr(001) surface, which corresponds to a fraction of the number of atoms with majority spin in Cr(001) layers. On the other hand, the emission current from Cr/W{113} was comparable to conventional ?eld emitters so that ?gure of merit for spin polarized electron sources was two orders of magnitude higher than that for the Cr/W(001) emitter in previous strudy.
关键词： Chromium,Spin-polarized ?eld emitter,?eld emission
更新于2025-09-23 15:21:21
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Characterisation of elemental analysis, carbon sulphur analysis and impact test of stent manufacturing using medical grade ASTM F75 cobalt chromium (CoCrMo) by selective laser melting (SLM) technology
摘要： This paper explains and demonstrates the capabilities of metal additive manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 cobalt chromium powder. The elemental analysis (EDX-SEM), carbon sulphur analysis and Impact Test are being develop and tested and thus exploring the potential area of MAM process for future proof stent manufacturing. By alternatively switching to MAM, the step of production can be minimised and thus customisation of stent can be carried out according to the patient’s need. The suggested model of the stent was taken from the third-party vendor and fabrication was carried out using EOSINT M280 metal printer with the aid of Materialise Magics 19.0 software for support generation.
关键词： stent,scanning electron microscope (SEM),selective laser melting (SLM),cobalt chromium (CoCrMo),energy-dispersive X-ray spectroscopy (EDX),Metal additive manufacturing (MAM)
更新于2025-09-23 15:21:01
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Evaluation of the Efficacy of Erbium, Chromium-doped Yttrium, Scandium, Gallium, and Garnet Laser in Partial Pulpotomy in Permanent Immature Molars: A Randomized Controlled Trial
摘要： Introduction: The use of the erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser in vital pulp therapy contributes to the formation of dentin bridges and a sterile zone as well as the maintenance of the vitality of the pulp. However, no prior studies have used the Er,Cr:YSGG laser in partial pulpotomy of immature permanent teeth. The aim of this study was to compare the ef?cacy of partial pulpotomy treatment using mineral trioxide aggregate (MTA) alone and MTA with the Er,Cr:YSGG laser in permanent immature molars. Methods: A total of 90 caries-exposed permanent immature molar teeth were included and randomly divided into 2 groups: the MTA group (n 5 45) and the laser 1 MTA group (n 5 45). In the MTA group, MTA was applied to the exposed area on the pulp after bleeding control. In the same session, the tooth was restored with a composite resin. In the laser 1 MTA group, before MTA condensation, the Er,Cr:YSGG laser was applied to the exposure area. Patients were recalled at 1, 3, 6, and 12 months after treatment. The Mann-Whitney U and chi-Square tests were used for statistical analysis. Results: The success rate (95.5%) of the laser 1 MTA group was similar to that of the MTA group (88.8%). There was no signi?cant difference between groups in terms of the frequency of at least 1 pathologic clinical or radiographic failure at 12 months (P . .05). Conclusions: Partial pulpotomy treatment showed a high success rate in immature permanent molars; however, the use of the laser did not contribute to the success rate compared with MTA alone.
关键词： mineral trioxide aggregate,partial pulpotomy,Erbium, chromium-doped yttrium, scandium, gallium, and garnet laser,immature teeth
更新于2025-09-23 15:21:01
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Synthesis of highly fluorescent and water soluble graphene quantum dots for detection of heavy metal ions in aqueous media
摘要： Fluorescent graphene quantum dots (GQDs) are nanomaterials which possess unique properties that show great potential in different applications. In this work, GQDs were synthesized using graphene oxide (GO) as precursor via thermal treatment at high temperature. The obtained GQDs were highly fluorescent and were suitable for the determination of heavy metal ions. X-ray diffraction, FTIR spectroscopy, and UV visible spectroscopy confirm the formation of GQDs. TEM images show that formed GQDs have size ranging from 2 to 10 nm. Emission profile of aqueous GQDs was taken by exciting GQDs at different wavelength. The intensity of GQDs remains the same for 4–5 months. Furthermore, as prepared, GQDs were used for selective recognition of Fe3+, Pb+2, and Cr3+ from the bunch of different metal ions in aqueous media. Lower limit of detection obtained for Fe3+, Cr3+ and Pb2+ using GQDs were 50, 100 and 100 nM, respectively, which indicates that the GQDs can be utilized as a promising material for sensing of the heavy metal ions.
关键词： GQDs,Lead and chromium ions,Iron,Fluorescence
更新于2025-09-23 15:19:57
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Determination of Lead and Chromium in Aloe Vera Pulp and Aloe Vera-Based Cosmetics by Laser-Induced Breakdown Spectroscopy (LIBS)
摘要： This study focuses on the application of laser-induced breakdown spectroscopy (LIBS) to determine lead and chromium in pristine aloe vera and aloe vera based beauty soaps using the second harmonic (532 nm) of a Q-switched Nd:YAG laser. The optimal experimental conditions were evaluated to improve the sensitivity of the detection system by a parametric dependence study. The atomic transition lines at 405.7 nm and 425.4 nm were used as the analytical lines to determine lead and chromium, respectively. The LIBS system was calibrated for these toxic elements and the samples under analysis included 8.00–15.00 ppm by mass of lead and 5.00–12.00 ppm by mass of chromium, which are far above the safe permissible levels of these elements (i.e., 0.50 ppm for Pb and 1.00 ppm for Cr). The quantitative results were checked before and after normalization with the background and better outcomes were obtained when the spectrum was normalized with the background. The LIBS results were compared to the outcomes of selected samples by a standard analytical method, inductively coupled plasma – optical emission spectroscopy (ICP-OES). Both outcomes were in outstanding conformity implying the reliability of the LIBS measurements. The current study is attractive for the general evaluation of human health and specifically for the analysis of aloe vera based cosmetics.
关键词： chromium,Laser-induced breakdown spectroscopy (LIBS),aloe vera,lead
更新于2025-09-23 15:19:57