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Research on the “∞”-shaped laser scanning welding process for aluminum alloy
摘要： To solve the problems of poor quality and insu?cient joint strength of aluminum alloy weld, a laser scanning welding test platform for aluminum alloy was built. Taking the butt welding of 5052 aluminum alloy with 5 mm and 3 mm thick specimens as the research objects, the study of a “∞”-shaped laser scanning welding process was conducted, and the similarities and di?erences between the welding process and that of single pass laser welding were compared. The in?uence of “∞”-shaped laser scanning welding parameters on the weld formation was investigated by the factor variable method. The change of the surface morphology and dynamic evolution of the molten pool was observed by a high-speed camera system. The optimal combination of the welding parameters was obtained by an orthogonal test. The research showed that the “∞”-shaped laser scanning welding pool had good stability and a good weld quality. Under suitable welding parameters, the length and width of the molten pool could be increased signi?cantly compared with those of the single pass laser welding. The growth rate of the length and width could reach 110.19% and 57.69%, respectively. The surface of the weld was evenly distributed with dense ?sh scales, and the porosity was less than 1%. The tensile strength of the specimen could reach 205.242 MPa, which was 93% that of the base metal; the topography of fracture was full of dimples, and the metallographic structure of the weld was ?ne and distributed with equiaxed dendrites.
关键词： Weld appearance,Weld performance,Laser technique,“∞”-shaped laser scanning welding,Molten pool characteristics
更新于2025-11-28 14:24:20
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A novel Ag nanoparticles/TiO2 nanowires-based photodetector and glucose concentration detection
摘要： A unique vapour transport cum glancing angle deposition (VT-GLAD) technique was employed to fabricate titanium dioxide (TiO2) nanowires (NWs). The NWs were grown and assembled to form the clusters. Both brookite (412) and rutile (002) phase for TiO2 was obtained from X-ray diffraction (XRD). The d spacing of ~ 1.37 ? was calculated from the transmission electron microscopy (TEM) of TiO2 NWs, which corresponds to (002) crystal plane. The silver (Ag) nanoparticles (NPs) on TiO2 NWs were grown using thermal evaporation cum GLAD technique. The presence of Ag NPs on the TiO2 NWs enhanced the photoconduction as compared to bare TiO2 NWs device. The maximum photosensitivity of the Ag NPs/TiO2 NWs based device was recorded ~ 1.6 times compared to the bare TiO2 NWs based device at ? 2.5 V. The Ag NPs containing device was highly UV sensitive and maximum responsivity for the device was calculated to be ~ 2.3 A/W at 370 nm. The device also possessed high responsivity rejection (RR) ratio of ~ 6.5 between UV (370 nm) and visible (450 nm) light. The Ag NPs decorated TiO2 NWs based detector also showed response to white light. The different concentration of glucose into deionised (DI) water-based solution was detected precisely under white light illumination. The normalised (light/dark) detector current/glucose concentration value was decreased from ~ 0.19 to ~ 0.05 at ? 2.5 V, with an increase in glucose concentration into the solution from 40 mg/dl to 200 mg/dl.
关键词： photodetector,Ag nanoparticles,TiO2 nanowires,VT-GLAD technique,glucose concentration detection
更新于2025-11-21 11:01:37
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Cu nanoclusters in ion exchanged soda-lime glass: Study of SPR and nonlinear optical behavior for photonics
摘要： Nanomaterials with large optical nonlinearities have received considerable attention in the field of modern science and nanotechnology. In this paper, we have studied nonlinear optical and surface plasmon resonance properties and behavior of Cu nanoclusters formed in ion exchanged soda-lime glass. The soda-lime glasses were successfully doped with Cu nanoclusters in the ion-exchange process. The size of the clusters estimated from the optical absorption spectroscopy results closely matched with those obtained from the transmission electron microscopy data. The results revealed that spherical shaped Cu nanoclusters were homogeneously distributed in the glass matrix and the size of the Cu nanoclusters varied from 4 to 10 nm. The structure and chemical state were further analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The nonlinear optical behavior of the materials was analyzed using femtosecond Z-scan technique. The nonlinear refraction index (n2), nonlinear absorption coefficient (β) and the third-order nonlinear optical susceptibility (χ(3)) were estimated to be -1.72 × 10?17 m2/W, 9.96 × 10?11 m/W, and 0.56 × 10?11 esu, respectively, which shows possible application in the field of photonics.
关键词： Surface plasmon resonance,Z-scan technique,Metal forming and shaping,Structural,Nanoparticles
更新于2025-11-20 15:33:11
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dz2 Orbitals Mediated Bound Magnetic Polarons in Ferromagnetic Ce Doped BaTiO3 Nanoparticles and its Enriched Two Photon Absorption Cross Section
摘要： Enriched ferromagnetism and two photon absorption (TPA) cross section of perovskite BaTiO3 nanoparticles are indispensible for magnetic and optical data storage applications. In this work, the hydrothermally synthesized Ce doped BaTiO3 nanoparticles exhibit the maximum room temperature ferromagnetism (4.26×10-3 emu/g) at 4 mol% due to the increase of oxygen vacancies as evidenced by X-ray photoelectron, electron spin resonance spectroscopies and density functional theory (DFT) calculations. Hence, the oxygen vacancy constituted bound magnetic polaron (BMP) model has been invoked to explain the enhancement of ferromagnetism. BMP theoretical model indicates the increase of BMP magnetization (M0, 3.0 to 4.8×10-3 emu/g) and true spontaneous moment per BMP (meff, 4 to 9.88×10-4 emu) on Ce doping. DFT calculations show that BMPs mediate via Ti d orbitals leading to the ferromagnetism. Besides, it is understood that the magnetic moment induced by Ce at Ba site is higher than Ce at Ti site in the presence of oxygen vacancies. Open aperture Z-scan technique displays the highest TPA coefficient β (7.08×10-10 m/W) and TPA cross section σTPA (455×104 GM) at 4 mol% of Ce as a result of robust TPA induced excited state absorption. A large σTPA is attributed to the longer excited state lifetime τ (7.63 ns) of charge carriers created by oxygen vacancies and Ce ions which encounter several electronic transitions in the excited sub-states.
关键词： Ce doping,oxygen vacancies,bound magnetic polarons,two photon absorption,DFT calculations,Z-scan technique,BaTiO3 nanoparticles,ferromagnetism
更新于2025-11-19 16:56:35
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Latent fingermark detection using functionalised silicon oxide nanoparticles: Method optimisation and evaluation
摘要： The application of nanoparticles for latent fingermark detection has been reported in the literature over the past two decades. One of the nanoparticles that shows promise to become a routine technique is functionalised silicon oxide nanoparticles (SiO2 NPs). In a recent optimisation of the technique, the use of carboxyl-functionalised SiO2 NPs doped with luminescent ruthenium complex was proposed as a breakthrough for latent fingermark detection. In this study, the aforementioned functionalised SiO2 NPs were extensively evaluated. Modification and optimisation of the original detection parameters were performed to enhance detection quality and improve applicability. Various detection parameters were evaluated and assessed. A lower concentration of the functionalised nanoparticles used in the colloidal dispersion was determined to offer improved detection effectiveness. A combination of increased bath temperature and reduced immersion time was found to produce good overall results. A set of modified detection parameters was suggested for the use of the functionalised SiO2 NPs to detect latent fingermarks. Performance of the modified detection parameters was compared against that of the published detection method. Comparison experiments were carried out on fingermark specimens deposited on aluminium foil, transparent polypropylene plastic and green polyethylene plastic. Three donors (weak, average and strong) and two age intervals (ten days and three months) were considered in the comparison study. Evaluation of the results suggested that the overall performance of the modified method for latent fingermark detection was superior to that obtained using the previously published detection parameters.
关键词： Bath temperature,Detection effectiveness,Method modification,Colloidal,Surface functionalisation,Luminescence technique
更新于2025-11-19 16:46:39
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Growth, Luminescence and Scintillation Characterization of Disodium Di-tungstate (Na2W2O7) Crystal Scintillator
摘要： A single crystal of Na2W2O7 was grown by using the conventional Czochralski technique. The crystal structure of the grown sample was veri?ed by using a powder X-ray di?raction (XRD) analysis. The luminescence, as well as scintillation, properties of the crystals were evaluated at room temperature. The emission spectra of the crystal were obtained by irradiating the sample with X-ray and proton sources. The trap level of the grown crystal was studied from 325 K to 500 K, and di?erent kinematic parameters were calculated. The scintillation properties such as; energy resolution, light yield, ?uorescence decay time and α/β ratio of the crystal, were studied by using γ- (662 keV from 137Cs) and α- (5.4 MeV from 241Am) sources. The luminescence and the scintillation results revealed that the Na2W2O7 crystal would be a good material for the dark matter search and for high-energy physics experiment.
关键词： Czochralski technique,Na2W2O7,Dark matter search,Luminescence and scintillation
更新于2025-11-14 15:30:11
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TiO <sub/>2</sub> metasurfaces: From visible planar photonics to photochemistry
摘要： TiO2 metasurfaces have been intensively studied in the past few years. To date, the TiO2 metadevices only used their high reflective index (n). The controllable light extinction coefficient (k) of TiO2 has not been exploited yet. Here, we converted TiO2 metasurfaces to black TiO2 metasurfaces and explored their new opportunities in photochemistry. A complementary metal oxide semiconductor (CMOS)–compatible technique has been developed to reversibly and precisely control the absorption of TiO2 metasurfaces without spoiling their internal nanostructures. Consequently, two types of black TiO2 metasurfaces were realized for photochemical experiments. The metasurface with an ultrawide absorption band can substantially enhance the white light absorption and accelerate the solar-based photochemistry process by a factor of 18.7. The other metasurface with an absorption band of <20 nm only responded to the resonant wavelengths, making the photochemistry process capable of being monitored in real time. In addition, the reversible switch between normal and black states makes TiO2 metasurfaces suitable for dynamic metadevices as well.
关键词： photochemistry,CMOS-compatible technique,black TiO2,dynamic metadevices,TiO2 metasurfaces
更新于2025-10-24 16:33:39
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Third Order Nonlinear Properties of Pure and Na doped L-Arginine Acetate Single Crystal by Z-scan Technique
摘要： Single crystals of pure and Na doped L-arginine acetate (LAA) has been successfully grown from aqueous solution by slow evaporation technique. The crystalline qualities of the grown crystals were confirmed by powder X-ray diffraction studies. The nonlinear refractive index n2 and nonlinear susceptibility c(3) have been measured through the Z-scan technique. The results indicate that the compound exhibits reverse saturation absorption and self defocusing performance. Non-linear absorption co-efficient (b), the non-linear refractive index (n2), the real and imaginary parts of non-linear susceptibility c (3) have been measured at 632.8 nm.
关键词： Z-scan Technique,Na doped L-arginine acetate (LAA),Crystal
更新于2025-09-23 15:23:52
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Structural and Diffuse Reflectance Study of Cr-Doped ZnO Nanorod-Pigments Prepared via Facile Thermal Decomposition Technique
摘要： Ceramic coloured nanopigments are promising for commercial cool paint applications. This study was carried out to examine the near infrared (NIR) reflectivity of Cr-doped ZnO nanopigments prepared by simple thermal decomposition of zinc acetate dihydrate and chromium(III) acetate hydroxide as precursors of Zn and Cr, respectively. XRD, FTIR and SEM have been used to characterize the microstructure and morphological properties of the synthesized nanopigments. The obtained results referred to ZnO wurtzite hexagonal structure in absence of other ZnO phases or any phases based on chromium. The obtained particles of the investigated samples are uniform rod-like shape with average diameter about 50 nm. The diffuse reflectance measurements exhibited the decrease in NIR reflectance with increasing Cr content. The sample with lower content of Cr, 0.5 wt% of Cr precursor to Zn precursor, exhibited a maximum value of NIR solar reflectance (R*) of 53.1% with respect to the other doped samples. The optical energy gap (Eg) of the investigated nanopigments were calculated using diffuse reflectance spectrum in view of Kubelka–Munk assumptions and the obtained average value of Eg is 3.219 eV with small standard deviation ± 0.015 eV.
关键词： Thermal decomposition technique,ZnO,Structure and optical properties,Pigments
更新于2025-09-23 15:23:52
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Effect of Object Position in Cone Beam Computed Tomography Field of View for Detection of Root Fractures in Teeth with Intra-Canal Posts
摘要： Background: Vertical root fracture (VRF) is a common problem in endodontically treated teeth. Due to its poor prognosis, a reliable technique must be used to make an accurate diagnosis. Cone beam computed tomography (CBCT) has been recently introduced for maxillofacial imaging. Despite the high diagnostic value of this method, metal artifacts resulting from intra-canal posts still make the detection of VRFs challenging. Objectives: This study aimed to assess the effect of object position in the field of view (FOV) of CBCT on detection of VRFs in teeth with intra-canal posts. Materials and Methods: The crowns of 60 extracted premolar teeth were cut at the level of cementoenamel junction (CEJ). Root canals were filled with gutta-percha and filling of the coronal 2/3 of the root canals was subsequently removed to fabricate intra-canal cast posts. The teeth were randomly divided into two groups of 30. Fracture was induced in group one using an Instron machine. Group two was considered as the control group with no fracture. All teeth were then randomly positioned and scanned in five different positions starting at the center of the FOV as well as right, left anterior and posterior relative to the center (3, 9, 12, and 6 O’clock) via the New Tom VGI CBCT unit. Two observers evaluated images for VRFs. Sensitivity and specificity of fracture diagnosis in each position was calculated in comparison with the gold standard. Wilcoxon test was used for data analysis. Results: Considering deterministic and probabilistic diagnostic parameters, probabilistic sensitivity was similar in all positions; but probabilistic specificity of the center position (65.1%) was significantly higher than that of 6 and 12 O’clock positions. Considering the deterministic diagnostic parameters, the overall sensitivity and specificity values decreased in all positions in FOV, but sensitivity of the center position of FOV was significantly higher than that of other positions; specificity was significantly higher at the 3 O’clock position (58.5%). Conclusion: Concerning the positions in FOV, the center position is suitable for detection of VRF in teeth with intra-canal posts due to significantly higher sensitivity at this position. The 3 O’clock position would be suitable for assessment of intact teeth without fractures due to significantly higher specificity at this position.
关键词： Post and Core Technique,Position,Tooth Fracture,Cone-Beam Computed Tomography
更新于2025-09-23 15:23:52