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Fast Classification of Geographical Origins of Honey Based on Laser-Induced Breakdown Spectroscopy and Multivariate Analysis
摘要： Traceability of honey is highly required by consumers and food administration with the consideration of food safety and quality. In this study, a technique named laser-induced breakdown spectroscopy (LIBS) was used to fast trace geographical origins of acacia honey and multi-floral honey. LIBS emissions from elements of Mg, Ca, Na, and K had significant differences among different geographical origins. The clusters of honey from different geographical origins were visualized with principal component analysis. In addition, support vector machine (SVM) and linear discrimination analysis (LDA) were used to quantitively classify the origins. The results indicated that SVM performed better than LDA, and the discriminant results of multi-floral honey were better than acacia honey. The accuracy and mean average precision for multi-floral honey were 99.7% and 99.7%, respectively. This study provided a fast approach for geographical origin classification, and might be helpful for food traceability.
关键词： geographical origin,classification,honey,laser-induced breakdown spectroscopy,multivariate analysis
更新于2025-09-23 15:19:57
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Laser-induced breakdown spectroscopy of uranium in the VUV range
摘要： Quantitative analysis of impurities in nuclear materials is necessary in a number of areas, including process control during manufacturing, quality control of products, or for nuclear forensics purposes. Due to the important handling constraints induced by the samples radioactivity and their containment inside airtight enclosures, optical analytical techniques have great advantages over standard ones that require sample preparation, like ICP-based techniques. Therefore, laser-induced breakdown spectroscopy (LIBS) is developed for fast quantitative analysis of impurities in uranium. Actinides are well-known to have a very large number of emission lines in the UV-visible spectral range, hence making the detection of trace or minor elements a real challenge. Therefore, in this study we explored the vacuum ultraviolet range (VUV), i.e. below 200 nm, in order to investigate if this spectral region is more favorable for elemental analysis of uranium by LIBS. As practically no data on VUV spectroscopy of uranium are available, we first analyzed the spectra obtained to assess the spectral density of uranium lines, both in the UV and VUV. Then, the detection limits of two elements, carbon and vanadium, were estimated. It was found that, in spite of a less dense and less intense uranium background in the VUV, this spectral region is not relevant for metal impurities whose spectra are marginally analytically useful in the VUV. Conversely, for non-metals having intense lines in the VUV, the detection limit can be significantly better than in the UV. This was already known for non-nuclear samples. This study extends that conclusion to nuclear materials and has important practical consequences on the implementation of a LIBS analyzer in a nuclear facility.
关键词： vanadium,uranium,Laser-induced breakdown spectroscopy,impurities detection,carbon,VUV range
更新于2025-09-23 15:19:57
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Quantification of calcium in infant formula using laser-induced breakdown spectroscopy (LIBS), Fourier transform mid-infrared (FT-IR) and Raman spectroscopy combined with chemometrics including data fusion
摘要： Laser-induced breakdown spectroscopy (LIBS), Fourier transform mid-infrared (FT-IR) and Raman spectroscopy combined with chemometrics were investigated to quantify calcium (Ca) content in infant formula powder (INF). INF samples (n=51) with calcium content levels (ca. 6.5-30 mg Ca/100kJ) were prepared in accordance with the guidelines of Commission Directive 2006/125/EC. Atomic absorption spectroscopy (AAS) was used as the reference method for Ca content determination. To predict Ca content in INF samples, partial least squares regression (PLSR) models that developed based on LIBS, Raman and FT-IR spectral data, respectively. The model developed using LIBS data achieved the best performance for the quantification of Ca content in INF (R2 (cross-validation (CV))-0.99, RMSECV-0.29 mg/g; R2 (prediction (P))-1, RMSEP-0.63 mg/g). PLSR models that developed based on data fusion of Raman and FT-IR spectral features obtained the second best performance (R2CV-0.97, RMSECV-0.38 mg/g; R2P-0.97, RMSEP-0.36 mg/g). This study demonstrated the potential of LIBS, FT-IR and Raman spectroscopy to accurately quantify Ca content in INF.
关键词： Fourier transform mid-infrared,laser-induced breakdown spectroscopy,chemometrics,Raman spectroscopy,calcium,infant formula
更新于2025-09-23 15:19:57
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Inner choroidal ischaemia and CNV due to handheld laser-induced maculopathy: a case report and review
摘要： There has been a sharp rise of reported handheld laser-induced maculopathy (HLIM) cases over the past decade, a concerning trend that may continue due to unregulated online access to high power lasers. Though HLIM has distinct clinical features, not uncommonly it may masquerade as other retinal disorders. It is critical therefore to recognise the clinical and multimodal imaging characteristics of this important and potentially devastating condition. As HLIM patients are typically young, unique issues need to be considered, such as delayed presentation, dif?cult history, poor compliance and behavioural or psychiatric comorbidity. This article will review the clinical and diagnostic features of laser injury, with a special emphasis on the multimodal retinal ?ndings. In addition, we present a unique case of HLIM, resembling the presentation of a placoid disease variant and illustrating choroidal ischaemia using advanced retinal imaging, that offers further insight into the mechanisms of laser injury and its complications. The issues addressed in this review aim to increase recognition of an increasingly important and trending condition with potentially profound visual complications.
关键词： HLIM,handheld laser-induced maculopathy,CNV,multimodal imaging,choroidal ischaemia
更新于2025-09-23 15:19:57
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Functionalization of Plastic Parts by Replication of Variable Pitch Laser-Induced Periodic Surface Structures
摘要： Surface functionalization of plastic parts has been studied and developed for several applications. However, demand for the development of reliable and profitable manufacturing strategies is still high. Here we develop and characterize a new process chain for the versatile and cost-effective production of sub-micron textured plastic parts using laser ablation. The study includes the generation of different sub-micron structures on the surface of a mold using femtosecond laser ablation and vario-thermal micro-injection molding. The manufactured parts and their surfaces are characterized in consideration of polymer replication and wetting behavior. The results of the static contact angle measurements show that replicated Laser-Induced Periodic Surface Structures (LIPSSs) always increase the hydrophobicity of plastic parts. A maximum contact angle increase of 20% was found by optimizing the manufacturing thermal boundary conditions. The wetting behavior is linked to the transition from a Wenzel to Cassie–Baxter state, and is crucial in optimizing the injection molding cycle time.
关键词： micro-injection molding,laser-induced periodical surface structures,surface wettability,replication
更新于2025-09-23 15:19:57
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Laser-Writing of Janus Graphene/Kevlar Textile for Intelligent Protective Clothing
摘要： Protective clothing plays a vital role in safety and security. Traditional protective clothing can protect human body from physical injure. It is highly desired if modern wearable electronics can be integrated into traditional protection suit to endow it with versatile smart functions. However, it is still challenging to integrate electronics into clothing through a practical approach while keeping the intrinsic flexibility and breathability of textiles. In this work, we realized the direct writing of laser-induced graphene (LIG) on Kevlar textile in air and demonstrated the applications the as-prepared Janus graphene/Kevlar textile in intelligent protective clothing. The C=O and N?C bonds in Kevlar were broken and the remaining carbon atoms were reorganized into graphene, which can be ascribed to photothermal effect induced by the laser irradiation. Proof-of-concept devices based on the prepared graphene/Kevlar textile, including flexible Zn-air batteries, electrocardiogram electrodes, and NO2 sensors, were demonstrated. Furtherly, we fabricated a self-powered and intelligent protective clothing based on the graphene/Kevlar textile. The laser induced direct writing of graphene from commercial textiles in air conditions provides a versatile and rapid route for the fabrication of textile electronics.
关键词： laser-induced graphene,Kevlar textile,NO2 sensor,textile electronics,photothermal effect
更新于2025-09-23 15:19:57
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Laser-Induced Graphene Paper Heaters with Multimodally Patternable Electrothermal Performance for Low-Energy Manufacturing of Composites
摘要： Low-energy manufacturing of polymeric composites through two-dimensional electrothermal heaters is a promising strategy over traditional autoclave and oven. Laser induced graphene paper (LIGP) is a recent emergent multifunctional material with merits of one-step computer aided design and manufacturing (CAD/CAM) as well as flexible thin nature. To fully explore its capabilities of in situ heating, herein, we adventurously propose and investigate the customizable manufacture and modulation of LIGP enabled heaters with multimodally patternable performance. Developed by two modes (uniform & nonuniform) of laser processing, the LIGP heaters (LIGP-H) show distinctively unique characteristics, including high working range (> 600 °C), fast stabilization (< 8 s), high temperature efficiency (~370 °C·cm2/W), and superb robustness. Most innovatively, the non-uniform processing could section LIGP-H into subzones with independently controlled heating performance, rendering various designable patterns. The above unique characteristics guarantee the LIGP-H highly reliable for in situ curing composites with flat, curve and even inhomogeneous structures. With enormous energy-saving (~85%), superb curing accuracy, and comparable mechanical strength, the proposed device is advantageous for assuring high-quality and high-efficient manufacturing.
关键词： polymeric composites,graphene papers,thin film heaters,flexible electronics,laser-induced graphene
更新于2025-09-23 15:19:57
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Femtosecond laser-induced surface structuring of the porous transport layers in proton exchange membrane water electrolysis
摘要： In proton exchange membrane water electrolysis (PEMWE) cells the performance and thus the conversion efficiency are influenced by the interface between the porous transport layer (PTL) and the catalyst layer (CL). In the following paper, this interface is modified by the use of femtosecond laser-induced surface structuring, so that the specific surface area of the titanium based fibers of the PTL is increased. The resulting morphology exhibits two roughness levels of (i) a relatively coarse structure featuring tips of a few micrometers in diameter and depth, which are each covered in turn by (ii) a substructure of smaller tips of a few to several hundred nanometers in diameter and depth. PEMWE electrochemical characterization and short-term stress tests reveal that the cell performance is increased due to the laser-structuring of the PTL surface towards the CL. For instance, the cell voltage is reduced by approximately 30 mV after 100 h at 4 A cm?2. These beneficial effects are observed over the entire current density range and thus correspond to a decreased equivalent cell resistance of at least 6 mΩ cm2 for electrical interfacial contact losses and at least 2 mΩ cm2 for mass transport losses. A physical characterization by scanning electron microscopy shows that the CL surface is much rougher and more jagged when using laser-structured fibers. Thus, the gaseous oxygen and the liquid water transport both from and to the active sites of the catalyst seem to be improved.
关键词： catalyst layer,cell performance,proton exchange membrane water electrolysis,porous transport layers,femtosecond laser-induced surface structuring
更新于2025-09-23 15:19:57
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High-accuracy prediction of carbon content in semi-coke by laser-induced breakdown spectroscopy
摘要： Semi-coke, as one kind of special coal resource with relatively high concentration carbon and low volatility, plays an important role in the coal chemical industry and city clean. Laser-Induced Breakdown Spectroscopy (LIBS) has been proved as an effective way to make an online analysis for the coal products. However, the lower volatility of semi-coke makes it hard to be pressed into a slice to get a smooth surface for a uniform laser-irradiation. Therefore, it is necessary to find an effective way to realize a high-accuracy LIBS detection for semi-coke application. Herein, two feasible ways of sample preparation are tried, one easy way is directly painting semi-coke powders on a tape that suitable for online fast monitoring, and the other complicated way is to mix binder into the semi-coke powder then that the uniformly and tightly coal slices are obtained, thus to improve the repeatability of measurement. Moreover, a totally new algorithm, support vector machine (SVM) combined with partial least square (PLS) regression(SVM-PLS), is utilized to establish an effective prediction model to make a high prediction accuracy. The coefficient of determination (R2), root mean square error of prediction (RMSEP), and average relative error (ARE) are 0.944, 0.90%, and 0.80%, respectively. In comparison with the result of the traditional PLS model, the SVM residual correction greatly improves the quality of the calibration curve and makes RMSEP and ARE reduced 0.17%, thus improves the prediction accuracy, which is much better than basic PLS regression. Meanwhile, the prediction error from binder mixed semi-coke slice is significantly reduced compared to that with directly painting samples on a tape. The maximum relative errors (MRE) are 2.71% and 5.19%, and the average RSD of the characteristic peaks are 12.1% and 16.2%, respectively, indicating that the easy way with painting sample on tape has little prediction uncertainties. Finally, in a three-day random test, the average RMSEP is 1.89% and average ARE is 1.74%, which also proves the binder additive can effectively reduce the matrix effect and enhance the stability of the spectrum for semi-coke measurement. The result proposes the proper LIBS analysis on semi-coke is a feasible and promising approach for on-line prediction of such kind of coal sample.
关键词： LIBS,prediction accuracy,Laser-Induced Breakdown Spectroscopy,semi-coke,carbon content,SVM-PLS
更新于2025-09-23 15:19:57
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Concentric multipass cell enhanced double-pulse laser-induced breakdown spectroscopy for sensitive elemental analysis
摘要： Although double-pulse laser-induced breakdown spectroscopy (DP-LIBS) is regarded as a promising technique in trace element analysis, its limit of detection (LOD) is not sufficient for some applications. The enhancement of spectral signal is the key to further improve the sensitivity of DP-LIBS. To further increase the sensitivity of DP-LIBS, a concentric multipass cell (CMC) enhanced DP-LIBS (CMC-DP-LIBS) technique is proposed for the first time, which makes full use of the energy of reheating laser by multi-reflection in CMC to enhance the spectral signal and lower LOD. 2.3 times signal enhancement of Mn I 403.08 nm line and 2.3 times decrease of LOD of Mn on the surface of zinc bulk compared with traditional orthogonal reheating DP-LIBS were attained. The signal enhancement factor can reach to 3.6 theoretically with the increase of reflectivity and the sizes of mirrors of CMC. This CMC-DP-LIBS provides a new approach to further improve the sensitivity of DP-LIBS and promotes its application in trace element detection.
关键词： Double-pulse,Concentric multipass cell enhancement,Laser-induced breakdown spectroscopy,Detection limit
更新于2025-09-23 15:19:57