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The technology of nuclear reactors is evolving rapidly, driven by the pursuit of more powerful and efficient systems. The Small Lead-based Reactor (SLR) represents an advanced nuclear reactor design that holds great promise for delivering enhanced power and efficiency. In the context of the SLR's fuel rod, the high-speed coolant flow within the reactor can induce vibration, potentially causing fretting wear and damage to the cladding. This study utilized the Burgreen correlation to establish an equivalence relationship between water and Lead-Bismuth Eutectic (LBE). An experiment was then conducted to simulate axial flow-induced vibration (FIV) of a simply supported fuel rod, employing an equivalent water loop. Flow-induced vibration characteristics in both the time and frequency domains were investigated at different flow speeds. The experimental results revealed a positive correlation between flow velocity and amplitude. The fuel rod exhibited low-frequency vibrations with a random pattern, registering frequencies around 14 Hz. These experimental findings can be leveraged to enhance the accuracy of numerical simulations for axial flow-induced vibration (FIV) of the fuel rod. Subsequently, the revised numerical model was applied to simulate FIV in the LBE environment using computational fluid dynamics (CFD), and the numerical results were found to be in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Low-loss, high-birefringence, bend-resistant hollow-core anti-resonant fibers for infrared wavelengths have important applications in the fields of precision interferometric sensing, laser systems, and optical communications. In this paper, an eight-tube cladding quasi-symmetric hollow-core anti-resonant fiber is proposed, and two other anti-resonant fibers are designed based on this fiber structure. The finite element analysis method is used to numerically analyze the limiting loss, birefringence coefficient, bending resistance, and other properties of the three optical fibers after the optimized design. The results show that the limiting loss of the three optical fibers at λ = 1.55 μm is lower than 10−4 magnitude, and all of them obtain a birefringence coefficient of 10−4 magnitude; at the same time, the three optical fibers have their own characteristics and advantages, and the first optical fiber can reach a birefringence coefficient of 9.25 × 10−4 at λ = 1.52 μm.The limiting loss at λ = 1.55 μm is 3.42 × 10−5 dB/km. The minimum bending radius of the three types of anti-resonant fibers is less than 40 mm, which represents good bending characteristics, and the eight-tube cladding quasi-symmetric optical fiber has a bending loss of less than 2.10 × 10−3 dB/km when the bending radius is 28 mm. The three types of optical fibers have obtained good results in improving the mutual constraints between low limiting loss and high birefringence, with better results than the other two types. The obtained results have high development potential. [ABSTRACT FROM AUTHOR]

The cladding of PMMA based polymer optical fibers (POFs) is doped by Rhodamine 6G (Rh6G) in the solution composed of water and methanol. Methanol is added in order to lower the doping temperature compared to that of pure water. Results show that addition of methanol, like raising temperature, can effectively accelerate the doping process. It is also found that there is a critical doping temperature for the solution of given methanol content. Above that temperature, the doping process dramatically impairs the fiber and the fiber loss increases too much for further application. In addition, Microscope observation of cross-sections of doped fibers indicate that Rh6G only diffuses into the cladding. Concentration measurement of Rh6G in the cladding and the core of doped fibers confirms that there is almost no Rh6G in the core. In short, this study reveals that the doping process of PMMA based POFs can be accelerated by adding methanol into water at the same temperature. Most importantly, the solution of methanol and water may be able to dissolve those dopants that are insoluble in pure water, making the aqueous solution based doping method suitable for more dopants. [ABSTRACT FROM AUTHOR]

Double-clad optical fiber with a multi-ring core profile doped with thulium and holmium fabricated by Modified Chemical Vapor Deposition Chelate Doping Technology (MCVD-CDT) is presented. The measured Tm2O3 and Ho2O3 complexes' weight concentrations were 0.5% and 0.2% respectively. Numerical analyses show weakly guiding conditions and 42.2 µm of MFD LP01 at 2000 nm. The low NA numerical aperture (NA = 0.054) was obtained for the 20/250 µm core/cladding ratio optical fiber construction. The emission spectra in the range of 1.6–2.1 µm vs. the fiber length are presented. The full width at half maximum (FWHM) decreases from 318 to 270 nm for fiber lengths from 2 to 10 m. The presented fiber design is of interest for the development of new construction of optical fibers operating in the eye-safe spectral range. [ABSTRACT FROM AUTHOR]

Optical fibers are an excellent sensor platform. However, the detection and analysis of media outside the cladding and coating of standard fibers represent a long-standing challenge: light that is guided in the single optical core mode does not reach these media. Cladding modes help work around this difficulty, as their transverse profiles span the entire cross-section of the fiber cladding and reach its outer boundary. In this tutorial, we introduce and discuss in detail two recent advances in optical fiber sensors that make use of cladding modes. Both concepts share optomechanics as a common underlying theme. First, we describe a spatially continuous distributed analysis using the optical cladding modes of the fiber. Light is coupled to these modes using Brillouin dynamic gratings, which are index perturbations associated with acoustic waves in the core that are stimulated by light. Unlike permanent gratings, which are routinely used to couple light with cladding modes, Brillouin dynamic gratings may be switched on and off at will and can be confined to short fiber sections at arbitrary locations in a random-access manner. Second, we present the extension of the cladding mode sensor concept to include acoustic rather than optical modes. The acoustic cladding modes may be stimulated and monitored by guided light in the single core mode, and their linewidths are modified by the elastic properties of surrounding media. The principles and analyses of both concepts are provided in detail, alongside examples of experimental setups and results. [ABSTRACT FROM AUTHOR]

This paper proposes a novel optical fiber sensor for highly sensitive Hg2+ detection based on Mach–Zehnder interference (MZI) structure and thiophene–chitosan hydrogel (TCH). We obtained the MZI structure by splicing the coreless fiber (CLF), thin core fiber, and CLF. And then, we etched the thin-core optical fiber cladding and assembled the TCH to produce a Hg2+ sensitive sensor. According to theoretical derivation and experimental verification, the detection sensitivity of the sensor to Hg2+ can reach 1.008 × 1011 mol l−1, and the detection limit is 5 × 10−13 mol l−1. The sensor also has performance stability within 24 h for concentration measurement, with an average standard deviation of 3.2 × 10−13 mol l−1 within an hour of observation. In addition, the sensor has the advantages of specificity, simple preparation, and low cost, and it is suitable for monitoring the concentration of Hg2+ in complex water systems. [ABSTRACT FROM AUTHOR]

Solution-mediated doping of polymer optical fibers (POFs) is a facile approach to obtain functional POFs. However, previous studies revealed that POFs may be severely impaired by the doping solution based on methanol or other organic solvents, and the fiber loss could substantially increase due to the solution doping process. This study proposes to dope POFs in aqueous solution dissolved with Rhodamine 6G (Rh6G) at elevated temperature. It is found that absorbed water molecules in POFs lead to fiber expansion at elevated temperature and produce voids large enough for Rh6G to diffuse into the fiber. Experimental results show that Rh6G can be successfully doped into the cladding of POFs in water within the temperature range of 60–80 °C. It is also found that raising temperature can significantly accelerate the doping process and lead to more Rh6G molecules diffusing into POFs. Most importantly, loss of POFs after doping in water even up to 80 °C doesn't increase, in contrast with doping in methanol or other organic solvents. In sum, doping of POFs in water is feasible and even preferable to organic solvents, though it requires that the dopant must be soluble in water. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is regarded as a chronic, immune-mediated disease that leads to the damage of various types of immune cells and signal networks, followed by inappropriate tissue repair and organ damage. RA is primarily manifested in the joints, but also manifests in the lungs and the vascular system. This study developed a method for the in vitro detection of RA through cyclic citrullinated peptide (CCP) antibodies and antigens. The diameter of a tilted-fiber Bragg grating (TFBG) biosensor was etched to 50 μm and then bonded with CCP antigens and antibodies. The small variations in the external refractive index and the optical fiber cladding were measured. The results indicated that the self-assembled layer of the TFBG biosensor was capable of detecting pre- and post-immune CCP antigen and CCP peptide concentrations within four minutes. A minimum CCP concentration of 1 ng/mL was detected with this method. This method is characterized by the sensor's specificity, ability to detect CCP reactions, user-friendliness, and lack of requirement for professional analytical skills, as the detections are carried out by simply loading and releasing the test samples onto the platform. This study provides a novel approach to medical immunosensing analysis and detection. Although the results for the detection of different concentrations of CCP antigen are not yet clear, it was possible to prove the concept that the biosensor is feasible even if the measurement is not easy and accurate at this stage. Further study and improvement are required. [ABSTRACT FROM AUTHOR]

The present study focuses on the evaluation of the mechanical properties degradation of Cr-coated Zr-alloy fuel cladding. The main objective of the work is to find a suitable methodology to evaluate the mechanical properties degradation of coated cladding by performing several separate effects experiments. Apart from the many positive effects of protective coatings on the overall cladding properties, coatings' general disadvantage is their reduced ability to tolerate plastic strain. Therefore, coating cracks might occur in the first stage of the hypothetical Loss of Coolant Accident (LOCA). The study is unique because of the consideration of coating cracks. Prior to the high-temperature (HT) oxidation, samples were subjected to either a scratch test or burst test, resulting in the creation of coating defects. The subsequent evaluation of the obtained data consisted of wavelength dispersion spectroscopy (WDS) and optical microscopy analysis and hydrogen content measurements. [ABSTRACT FROM AUTHOR]

Films of zinc telluride (ZnTe) were deposited on the surface of a chemically thinned section of an optical fiber by metalorganic chemical vapor deposition. The boundary values of temperatures and the concentration ratios of the initial tellurium and zinc precursors at which the synthesis of ZnTe coatings is possible are determined. The influence of the position of the thinned part of the optical fiber in the reactor on the growth rate of films on the side surface of the fiber was studied, on the basis of which, the parameters of the deposition zone were determined. By placing a section of an optical fiber with an etched cladding in the center of this zone, sensitive elements for refractometers were created. The principle of their operation is based on the dependence of the spectral position of the lossy mode resonance (LMR) maximum on the refractive index (RI) of the external medium. It has been found that even thin films deposited on a light guide in a continuous process have cracks. It is shown that the interruption of the deposition process makes it possible to avoid the appearance of defects in the zinc telluride layers even with the repeated deposition of the sensor. The sensitivity of the spectral position of the LMR to changes in the RI of aqueous sodium chloride solutions in the range from 1.33 to 1.35 for the first transverse electric and transverse magnetic LMRs was 6656 and 6240 nm per refractive index unit, respectively. [ABSTRACT FROM AUTHOR]

Herein, aqueous ammonium sensing characteristics of polyvinylpyrrolidone (PVP) capped silver nanoparticles (Ag-NPs) coated optical fiber-based sensors are presented. The PVP-capped Ag-NPs were prepared using cold and modified polyol synthesis methods. Aqueous ammonium detection was carried out by the surface plasmon resonance (SPR) effect observed in the Ag-NPs coated optical fiber system. The effect of cold and modified polyol synthesis methods on optical sensing performance was studied. The optical fiber cladding was modified with PVP-capped Ag-NPs according to the standard protocol for sensing investigation. The probe sensing response was analyzed for varying concentrations of ammonium ions on red, green, and blue LEDs. The sensor characteristics, viz., sensing response, repeatability, calibration curve, and ambient light effect, were investigated for PVP capped Ag-NPs coated optical fiber-based sensor. The PVP capped Ag-NPs synthesized via the polyol synthesis method showed a detection limit of 48.9 mM, 1.33 mV/M sensitivity, and an excellent linear relationship (R2 = 0.9992) between voltage and ammonium ion concentration in the range of 0.054–13.4 M concentration. On the other hand, PVP capped Ag-NPs synthesized using the cold synthesis method showed a detection limit of 159.4 mM, a sensitivity of 0.06 mV/M, and a poor linear relationship (R2 = 0.4588) between voltage and ammonium ion concentration in the range of 0.054–13.4 M concentration. The results indicate that the PVP-capped Ag-NPs synthesized using the polyol synthesis method exhibit enhanced ammonium ion sensing compared to the cold synthesis method. [ABSTRACT FROM AUTHOR]

We present a robust, fiber-based endoscope with a silver direct-laser-written structure for radio frequency (RF) emission next to the optical fiber facet. Thereby, we are able to excite and probe a sample, such as nitrogen-vacancy (NV) centers in diamond, with RF and optical signals simultaneously and specifically measure the fluorescence of the sample fully through the fiber. At our targeted frequency range of around 2.9 GHz, the facet of the fiber core is in the near-field of the RF-guiding silver structure, which comes with the advantage of an optimal RF intensity decreasing rapidly with the distance. By creating a silver structure on the cladding of the optical fiber, we achieve the minimal possible distance between an optically excited and detected sample and an antenna structure without affecting the optical performance of the fiber. This allows us to realize a high RF amplitude at the sample's position when considering an endoscope solution with integrated optical and RF access. The capabilities of the endoscope are quantified by optically detected magnetic resonance (ODMR) measurements of an NV-doped microdiamond that we probe as a practical use case. We demonstrate a magnetic sensitivity of our device of 17.8 nT / H z when measuring the ODMR exclusively through our fiber and compare the sensitivity to a measurement using a confocal microscope. Moreover, the application of our device is not limited to NV centers in diamonds. Similar endoscope-like devices combining optical excitation and detection with radio frequency or microwave antenna could be used as a powerful tool for measuring a variety of fluorescent particles that have so far only been investigated with bulky and large optical setups. Furthermore, our endoscope points toward precise distance measurements based on Rabi oscillations. [ABSTRACT FROM AUTHOR]

In the present work we have developed and realized a high core-to-cladding diameters ratio active optical fibers operated in a single-mode regime due to specially designed structure containing boron-doped and fluorine-doped rods. The beam quality at the output of the realized fibers was studied by three independent methods: near field investigation, M2 technique and S2 technique. According to the obtained results, the developed approach allows efficient suppression high-order-modes (first of all—LP11 mode) in the core and achieves a diffraction-limited beam at the output of the appropriately bent fiber (suppression of unwanted modes was better than 30 dB). Additionally, it is shown that application of such approach allows for increased bent-resistance of the fundamental mode and realizes polarization-sensitive amplification. [ABSTRACT FROM AUTHOR]

Plastic scintillators (PS) allow design of portative lightweight devices for quantification of low‐activity radiation sources. We have recently suggested a new type of organic fluorophores based on triphenyl pyrazoline (PZ) derivatives with high fluorescence quantum yield showing high radioluminescence when combined with a polyvinyltoluene (PVT) matrix. In this publication we report on radioluminescence properties of the PZ−X family with various halogen substitution (X=F, Cl, Br, I), or having vinyl functional group (vPZ, X=vinyl). PS based on such fluorophores and PVT matrix can be prepared as bulk samples, micrometer size beads or cladding on optical fibers. Application of fluorophores with vinyl functional groups enabled their enhanced interaction with the matrix due to covalent bonding between the components. We demonstrate high performance of PZ−X fluorophores and especially vPZ fluorophore in fabrication of nanocomposites for detection of various types of radiation. Scintillators have enhanced gamma ray detection capabilities with an addition of triphenyl Bi, or Gd2O3 nanoparticles. High fluorescence quantum yield and luminosity of PZ fluorophores allows dramatical reduction of their content in PS systems. Mechanisms of energy transfer and conversion during scintillation process are discussed. Special consideration is given to enhancement of α/β and neutron/gamma (n/γ) pulse shape discrimination (PSD) function of the developed scintillators. [ABSTRACT FROM AUTHOR]

This study attempts to analyze the microstructure and interface behavior of aluminum 6061 (Al 6061)-Vgrooved stainless steel (SS304) explosive cladding by numerical and experimental methods. Numerical simulation was performed by Smoothed Particle Hydrodynamics (SPH) technique, in ANSYS AUTODYN, and the results are correlated with experimental outcome. The machining of V-grooves on the base plate transform the melted layer formed in conventional cladding (without grooves on the base plate) into a smooth undulating interface, for a similar experimental condition. The flyer plate and collision velocities, observed in numerical simulation, are in good agreement to the analytical expectations. The pressure developed in the flyer plate is higher than the base plate and the maximum pressure is witnessed at the collision point irrespective of grooved base plate or otherwise. The temperature developed in the collision point of conventional explosive cladding exceeds the melting point of both the participant metals, whereas, it exceeds the melting point of aluminum alone, in case of V-grooved base plate cladding. The shear and impact strengths of the V-grooved base plate clads are higher than the conventional clads and the fracture surfaces exhibit mixed modes of fracture. [ABSTRACT FROM AUTHOR]

In the present study, the tensile creep behaviour of three various cladding tubes of the Zr1%Nb alloy has been studied in the a-Zr region at 3501C, which corresponds to the operational service conditions of the cladding tubes in nuclear light-water reactors. Tensile creep tests under the high constant applied stress region from 150 to 260MPa have been carried out at the transition from the power-law (PL) to the power-law breakdown (PLB) regimes. It was found that all dispersion strengthened Zr1%Nb cladding alloys under investigation reach the PLB regime at values of the compensated applied stress s/G above approximately 8 × 10-3, where the stress exponent n of the minimum creep rate 1em (n = (n ln aem/a ln s)T) then dramatically increases from the value of ~ 6 with increasing stress ratio s/G. The fact that all experimental results for both the PL and PLB obey the Monkman-Grant relationship supports the idea that the creep mechanism in the PL and PLB does not change qualitatively and indicates a close link between the deformation and fracture processes in both creep regimes under investigation. However, future experiments could be carried out at different testing temperatures within the PLB regime to verify the controversial contemporary views. [ABSTRACT FROM AUTHOR]

This paper presents the detection of ammonia in water using a balloon-like fiber optic sensor coated with Oxazine 170 perchlorate and polydimethylsiloxane (PDMS). The sensor was prepared by removing a middle portion of a plastic optical fiber cladding using acetone. The uncladded fiber optic sensor was then bent into a balloon-like shape using a 3D printed fiber holder to fix the diameter of the bent structure and a shrink tube to maintain the curvature of the balloon-like structure. A thin layer of Oxazine 170 perchlorate (sensing material) was then deposited on the fiber surface before it was dip coated with PDMS for the protection of the sensing material. Experimental results revealed that the sensor has linear relationship with ammonia concentration ranging from 0 mg/L to 15 mg/L. Moreover, the sensor managed to achieve the sensor sensitivity of 0.006 (mg/L)−1, linearity of 0.9154, resolution of 1.6667 mg/L, LOD of 2.9556 mg/L, average stability precision of 99.8 % and RSD of 0.0308 %. [ABSTRACT FROM AUTHOR]

We designed and fabricated a photonic crystal surface emitting laser (PCSEL) with vertically integrated diffractive optical elements on their top to study the mechanism of static beam steering on a single chip. The deflected output beam by the self-formed periodic ITO cladding layer of the PCSEL can be further steered by changing the grating period and azimuthal angle of the diffractive gratings relative to the photonic crystal. Through the analysis of photonic band structure and lasing characteristics, the periodic ITO structure is coupled to the photonic crystal band, whereas the integrated grating serves the diffractive function only. The findings pave the way for the design of PCSELs enabling single or multiple output beam with varying direction capability. This type of laser is regarded as an ideal light source for various applications, such as light detection and ranging and three-dimensional sensing systems. [ABSTRACT FROM AUTHOR]

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The excellent material properties of single crystal sapphire fibers promise great advantages in applications related to harsh environment optical sensing, high laser power delivery, and high-resolution/sensitivity optical spectroscopy. However, the lack of viable cladding for confining light propagation in sapphire fibers with negligible transmission loss has restricted their practical applications. Despite great efforts in engineering either a low-refractive-index cladding layer or highly reflective mirror layer as sapphire fiber surface coatings, confining light propagation within sapphire fibers remains difficult in practice since such surface coatings fail to function due to increased thermal stress and fast erosion in environments with extremely high temperatures (>1000 °C) and chemically reactive species/gases. Here, we demonstrate a method for creating nanoscale cavities/voids in sapphire as effective fiber cladding structures that are thermally robust even at 1700 °C using hydrogen ion implantation. Material analysis of implanted sapphire crystals indicates that such nanoscale cavities play a key role in reducing the refractive index in sapphire crystals. [ABSTRACT FROM AUTHOR]

The damping properties and specifically the bend losses of polymer optical fibres (POFs) have so far only been documented by experimental work, investigating bending parameters such as bending radius, length, and distance of the bends. Even though damping mechanisms and causes are well-known, no simple, generally valid formula exists. Here, a simulation technique is shown that allows producing an optical model for any bending geometries of melt-spun polymer optical fibres. The developed model takes all relevant loss mechanisms into account, especially regarding the scattering losses at the interface of core and cladding as well as those of the cladding-air interface. The latter is caused by interfacial roughness for which experimental data have been obtained by atomic force microscopy measurements. To show the validity of the simulation, the model is compared to experimental results for several fibres and a variety of geometries. The variance between model and experimental data is low (S < 4.6%). The model not only contributes to improving the understanding of the optical properties of POFs, but it also has direct applicability to the design of photonic textile sensors for medicine, where the fibres are incorporated with small bending radii. [ABSTRACT FROM AUTHOR]

In this paper, the design method of few mode elliptical ring core fiber (E-RCF) supporting up to 10 spatial linearly polarized (LP) modes is proposed. With the support of central circular hole, the maximum numbers of modes are generated using finite element method. Optical mode characteristics are optimized in two way; using the geometry properties of the elliptical ring core and radius of central hole region. Further, the mode performance is computed with the function of both ellipticity ratio (ρ) and wavelength. The results show that 10 distinct LP mode is adequately tuned in order to get higher index difference approximation ( Δ n eff ) to reduce the computational complexity. The results show for Δ n eff between the adjacent modes and reported as larger than 18.80 × 10−4 at ρ = 2.5 and larger than 17.30 × 10−4 at the wavelength of 2 μm. The work also describes the E-RCF sustainability in the IoT environment and it promises for better paly upon the user demand with transmitting dense of data. [ABSTRACT FROM AUTHOR]

A novel circular shaped metamaterial optical fiber with semiconductor core, metal/dielectric clad is numerically investigated. To surpass higher absorption loss and instability of noble metal, the core guiding medium of the fiber is comprised by crystalline germanium (Ge). The fiber is interrogated in terms of uniaxial permittivity, mode index, dispersion profile, effective area, nonlinearity, power fraction for different thickness (Cm = Cd, Cm > Cd, Cm < Cd) of Ag/Al2O3 using finite element method. In addition, it is shown how increased Ag/Al2O3 pair enhances optical properties especially for low loss which is reported as 0.025 dB/m with AMM cladding and 0.007 dB/m for layered cladding region. Hence, the proposed structure with comprising material is a promising candidate for mid-infrared applications. [ABSTRACT FROM AUTHOR]

We proposed and experimentally demonstrated a technique for the suppression of unwanted modes in double-clad fibers with a high core-to-clad diameter ratio by introducing high-index absorbing inclusions into the first cladding of the fibers. These inclusions disturb the shape of undesirable modes, and a noticeable part of the power becomes localized inside the inclusion, resulting in an increase in the propagation loss of these modes. Two fiber designs were studied and realized: one with cylindrical symmetry and an absorbing high-index ring as the inclusion and another with high-index absorbing rods inserted around the fiber core. In both cases, the possibility of achieving perfect single-mode propagation was demonstrated both theoretically and experimentally. [ABSTRACT FROM AUTHOR]

Cladding light strippers are essential components in high-power fiber lasers used for removal of unwanted cladding light that can distort the beam quality or even damage the whole fiber laser system. In this study, an Atomic Layer Deposition system was used for the first time to prepare the cladding light stripper devices using a 40 nm thick zirconia layer grown on optical fiber. The thickness of the zirconia coating was confirmed using the Scanning Electron Microscopy (SEM) and the Ellipsometry techniques. The elemental analysis was also performed using the wavelength dispersive X-ray spectroscopy technique. The Raman spectroscopy and XRD data confirm the structure of the atomic layer deposition-grown zirconia thin films to be predominantly amorphous. The cladding light stripper devices formed using the zirconia thin films with the lengths of 8.5 and 15.5 cm were able to strip approximately 30% (~1.5 dB) and 40% (~2.3 dB) of the unwanted cladding light. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2-Mercaptobenzimidazole/Polyvinylpyrrolidone functionalized gold nanoparticles. • Optical fiber for copper ion detection-based wave-based sensor. • Optical fiber sensor was studied for various concentrations of copper ions. • The sensor exhibits a polynomial response to increasing copper ion concentration. Gold nanoparticle-based optical fiber sensors are extensively utilized for the development of chemical sensors. The optical sensing capabilities of the chemical sensor are improved by the localized surface plasmon resonance that is linked with the gold nanoparticles. This study introduces a modified optical fiber sensor with cladding, which is coated with functionalized gold nanoparticles (Au NPs) containing 2′-mercaptobenzimidazole (MBI)/polyvinylpyrrolidone (PVP) to detect copper (Cu+2) ions. The study investigated the Cu2+ ions sensing capabilities of optical fiber under varying concentrations of PVP while maintaining a constant concentration of Cu+2ions. The optical fiber sensor's output voltage increased upon the addition of Cu2+ ions, as observed in all samples. The sensor's response was analyzed for Cu2+ ions concentrations ranging from 100 to 1000 ppm. The sensor displays a polynomial relationship with increasing Cu2+ ions concentration. The optical fiber sensor exhibits higher selectivity towards Cu2+ ions compared to sodium, potassium, ammonium, calcium, zinc, phosphate, nitrate, and chlorine ions. [ABSTRACT FROM AUTHOR]

Highlights • Electromagnetic field does not change the phase composition of the coating. • Electromagnetic field can change the temperature gradient. • Electromagnetic field can improve the microstructure of the coating. • Electromagnetic field can reduce the cracks and improve the microhardness of the coating. Abstract Laser cladding Ni-base coatings were prepared on pure iron assisted by an electromagnetic compound field. The microstructure, phase composition, crack and microhardness of the cladding coatings were investigated. Results indicated that laser cladding Ni-base coatings with and without the electromagnetic field was composed of γ-(Fe, Ni), CrB, Cr 7 C 3 , Ni 3 B and Ni 2 B. The electromagnetic compound field could promote the transformation of γ-(Fe, Ni) to equiaxed crystals. The volume fraction of hard phase CrB can be increased by electromagnetic field. Mechanical scouring effect of electromagnetic stirring makes hard phase Cr 7 C 3 form an independent rod structure. The number of cracks in coatings is decreased under the electromagnetic field. The average microhardness of cladding coatings increased to 923.7 HV 0.2. Under the combined action of the electromagnetic stirring and current thermal effect, the temperature gradient in the molten pool had an optimum value. That is, the value of AC current was 1200 A and magnetic flux intensity was 0.2 T. [ABSTRACT FROM AUTHOR]