Search

Excessive emissions of heavy metals not only cause environmental pollution but also pose a direct threat to human health. Therefore, rapid and accurate detection of heavy metals in the environment is of great significance. Herein, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with filter paper modified with bovine serum albumin-protected gold nanoclusters (LIBS-FP-AuNCs) for the rapid and sensitive detection of Cr 3+ and Mn 2+ . The filter paper modified with AuNCs was used to selectively enrich Cr 3+ and Mn 2+ . Combined with the multi-element detection capability of LIBS, this method achieved the simultaneous rapid detection of Cr 3+ and Mn 2+ . Both elements showed linear ranges for concentrations of 10-1000 μg L -1 , with limits of detection of 7.5 and 9.0 μg L -1 for Cr 3+ and Mn 2+ , respectively. This method was successfully applied to the determination of Cr 3+ and Mn 2+ in real water samples, with satisfactory recoveries ranging from 94.6% to 105.1%. This method has potential application in the analysis of heavy metal pollution.

This work presents the results of paper laser processing. It begins with the selection and examination of the processing parameters, then an examination of the properties of the modified papers and examples of applications of the developed modification method. The properties of laser-modified paper were studied using reflectance spectrophotometry to examine the colour aspects of the modified papers, scanning electron microscopy (SEM) and confocal microscopy for a morphological analysis, and Raman spectroscopy to analyse the papers under the influence of laser light. The influence of laser processing on the wettability of paper and the evenness of unprinted and printed paper was also investigated. The knowledge gained on paper surface modification with laser light was used to propose several applications, such as methods of marking, tactile detection, the controlled removal of optical brightener, ink, and metallised coatings from paper packaging, highlighting the design and aesthetics of paper. The developed laser-assisted method shows a promising, ecological approach to the design of many value-added paper products. [ABSTRACT FROM AUTHOR]

A pulsed laser engineering approach is developed to prepare novel functional graphene paper with graphitic nanospheres homogeneously decorated on the surface and the superior performance of engineered paper is revealed in matrix-free mass spectrometry (MS) detection and imaging. We demonstrate that the stability of graphene paper under intense irradiation can be dramatically increased through a designed laser engineering process by forming densely packed graphitic nanospheres on the paper surface. Moreover, the surface hydrophobicity is enhanced and electric conductivity is improved. The engineered graphene paper can image the invisible micro-patterns of trace amount molecules and increases the detection limit towards diverse molecules by over two orders of magnitude compared to the pristine graphene paper and commercial products in MS analysis.

This bibliometric study analyzed the 100 most-cited papers about the use of lasers and their modalities in dentistry. A search strategy was created using specific keywords related to the topic. A comprehensive search was then conducted in the Web of Science Core Collection (WoS-CC) database up to July 2021. Papers that addressed the application of any type of laser and its modalities in dentistry were included. Each paper was cross-matched with the number of citations on Scopus and Google Scholar. The following data were extracted from papers: title, number of citations, authorship, country, year of publication, journal, study design, subject, laser type, and oral health outcomes. The VOSviewer software was used to generate bibliometric networks. The total number of citations ranged from 120 to 4,124 and 23 papers received more than 200 citations. Papers were published from 1964 to 2015. Most papers were from Europe (42%) and Anglo-Saxon America (27%). The USA was the country with more top 100 papers (25%). Papers were published mainly in Lasers in Surgery and Medicine (15%) and Lasers in Medical Science (7%). VOSviewer maps demonstrated the existence of national and international research collaborations among institutions and authors. Most studies had a laboratory design (57%) and were about restorative dentistry (32%) and periodontics (21%). This bibliometric study of the top 100 most-cited papers on lasers in dentistry allowed a quantitative and qualitative analysis of this very promising research field, revealing a net of collaboration and the importance of this topic in dentistry. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Electrolyte Analysis in Blood Serum by Laser-Induced Breakdown Spectroscopy Using a Portable Laser" published in the journal Molecules. The correction addresses an error in Figure 6 of the original publication, where Figures 6b and 6c were duplicated. The corrected Figure 6, showing the quantitative analysis of elements in blood serum on filter paper (K, Na, and Ca), has been provided. The authors assure that this correction does not affect the scientific conclusions of the study. [Extracted from the article]

In laser speckle contrast analysis (LASCA) used for imaging of blood flow, besides the moving blood cells, the speckle pattern is also influenced by the imaging system and scattering properties of the laser-illuminated static surface. A latex microsphere (650 nm size) emulsion was covered with scattering semitransparent materials (Teflon foils, tracing paper). Speckle images were recorded with different exposure times (0.2 ms-500 ms), and correlation times were determined by parameterizing the theoretical contrast-exposure time function. The correlation times obtained for covered and uncovered microsphere emulsions were in good agreement. The possibility of obtaining comparable, setup-independent results in blood perfusion monitoring can contribute to better applicability of LASCA.

Immunoassay is one of the most important clinical techniques for disease/pathological diagnosis. Mass spectrometry (MS) has been a popular and powerful readout technique for immunoassays, generating the mass spectrometric immunoassays (MSIAs) with unbeatable channels for multiplexed detection. The sensitivity of MSIAs has been greatly improved with the development of mass labels from element labels to small-molecular labels. MSIAs are also expended from the representative element MS-based methods to the laser-based organic MS and latest ambient MS, improving in both technology and methodology. Various MSIAs present high potential for clinical applications, including the biomarker screening, the immunohistochemistry, and the advanced single-cell analysis. Here, we give an overall review of the development of MSIAs in recent years, highlighting the latest improvement of mass labels and MS techniques for clinical immunoassays., (© 2022. Springer-Verlag GmbH Germany, part of Springer Nature.)

An ultrafast and efficient strategy is developed to produce homogeneous GQDs through instantaneous photothermal gasification and recrystallization, revealing the promising potential for large-scale production. [Display omitted] Graphene quantum dots (GQDs) are attractive fluorescent nanoparticles that have wide applicability, are inexpensive, nontoxic, photostable, water-dispersible, biocompatible and environmental-friendly. Various strategies for the synthesis of GQDs have been reported. However, simple and efficient methods of producing GQDs with control over the size of the GQDs, and hence their optical properties, are sorely needed. Herein, an ultra-fast and efficient laser writing technique is presented as a means to produce GQDs with homogeneous size from graphene produced by the instantaneous photothermal gasification and recrystallization mechanism. Controlling the laser scan speed and output power, the yield of GQDs can reach to be about 31.458 mg/s, which shows promising potential for large-scale production. The entire process eliminates the need for chemical solvents or any other reagents. Notably, the prepared laser writing produced GQDs (LWP-GQDs) exhibit blue fluorescence under UV irradiation of 365 nm and the Commission Internationale de L'Eclairage (CIE) chromaticity coordinates is measured at (0.1721, 0.123). Overall, this method exhibits superior advantages over the complex procedures and low yields required by other existing methods, and thus has great potential for the commercial applications. [ABSTRACT FROM AUTHOR]

In the world of terahertz bands, terahertz beam deflection has gradually attracted substantial attention, due to its great significance in wireless communications, high-resolution imaging and radar applications. In this paper, a low-reflection and fast-fabricated terahertz beam deflection device has been realized by utilizing graphene oxide paper. Using laser direct writing technology, graphene oxide has been patterned as a specific sample. The thickness of the graphene oxide-based terahertz devices is around 15–20 μm, and the processing takes only a few seconds. The experimental results show that the beam from this device can achieve 5.7° and 10.2° deflection at 340 GHz, while the reflection is 10%, which is only 1/5 of that of existing conventional devices. The proposed device with excellent performance can be quickly manufactured and applied in the fields of terahertz imaging, communication, and perception, enabling the application of terahertz technology. [ABSTRACT FROM AUTHOR]

In this work, fabrication of frequency selective surface filters by coating paper with silver ink and subsequent laser etching the frequency filter pattern has been investigated. Three filter structures consisting of a combination of square and ring patches operating at 102, 113, and 126 GHz and with corresponding signal attenuation of −15.2, −15.4, and −14.5 dB were fabricated and simulated; −5 dB bandwidths were following, 93.3–112.2 GHz, 101.9–121.1 GHz, and 112.7–132.3, respectively. Also, the proposed screen printing with assistive laser etching could be used to reduce the number of used screens. Furthermore, paper based fabrication using a biodegradable ink could be an alternative fabrication process in future electronic manufacturing. [ABSTRACT FROM AUTHOR]

This study explores the adoption of laser-induced breakdown spectroscopy (LIBS) for the analysis of lateral-flow immunoassays (LFIAs). Gold (Au) nanoparticles are standard biomolecular labels among LFIAs, typically detected via colorimetric means. A wide diversity of lanthanide-complexed polymers (LCPs) are also used as immunoassay labels but are inapt for LFIAs due to lab-bound detection instrumentation. This is the first study to show the capability of LIBS to transition LCPs into the realm of LFIAs, and one of the few to apply LIBS to biomolecular label detection in complete immunoassays. Initially, an in-house LIBS system was optimized to detect an Au standard through a process of line selection across acquisition delay times, followed by determining limit of detection (LOD). The optimized LIBS system was applied to Au-labeled Escherichia coli detection on a commercial LFIA; comparison with colorimetric detection yielded similar LODs (1.03E4 and 8.890E3 CFU/mL respectively). Optimization was repeated with lanthanide standards to determine if they were viable alternatives to Au labels. It was found that europium (Eu) and ytterbium (Yb) may be more favorable biomolecular labels than Au. To test whether Eu-complexed polymers conjugated to antibodies could be used as labels in LFIAs, the conjugates were successfully applied to E. coli detection in a modified commercial LFIA. The results suggest interesting opportunities for creating highly multiplexed LFIAs. Multiplexed, sensitive, portable, and rapid LIBS detection of biomolecules concentrated and labeled on LFIAs is highly relevant for applications like food safety, where in-field food contaminant detection is critical. Graphical abstract.

Abstract: In this work we describe the design of our simulation tool for solid state lasers. The software is based on modules to simplify several complex processes. Primarily, the adaptation of laser physics (e.g. thermal lensing, optical wave) with the appropriate simulation technique. Another aspect is to provide the possibility of exchanging the applied calculation methods or even to change the representation of the computational domain on demand. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we demonstrate up to 30% increase in power density of carbon paper electrodes for vanadium redox flow batteries (VRFB) by introducing perforations into the structure of electrodes. A CO2 laser was used to generate holes ranging from 171 to 421 μm diameter, and hole densities from 96.8 to 649.8 holes cm−2. Perforation of the carbon paper electrodes was observed to improve cell performance in the activation region due to thermal treatment of the area around the perforations. Results also demonstrate improved mass transport, resulting in enhanced peak power and limiting current density. However, excessive perforation of the electrode yielded a decrease in performance due to reduced available surface area. A 30% increase in peak power density (478 mW cm−2) was observed for the laser perforated electrode with 234 μm diameter holes and 352.8 holes cm−2 (1764 holes per 5 cm2 electrode), despite a 15% decrease in total surface area compared to the raw un-perforated electrode. Additionally, the effect of perforation on VRFB performance was studied at different flow rates (up to 120 mL min−1) for the optimized electrode architecture. A maximum power density of 543 mW cm−2 was achieved at 120 mL min−1. [Copyright &y& Elsevier]

The graphene paper microsieves can be applied in the filtration of biological fluids or separation of solid particles from exploitation fluids. To produce graphene paper microsieves for specific applications, good control over fabrication should be achieved. In this study, a laser ablation method using a picosecond laser was applied to fabricate graphene paper microsieves. Holes in the microsieves were drilled using pulsed laser radiation with a pulse energy from 5 to 100 µJ, a duration of 60 ps, a wavelength of 355 nm, and a repetition rate of 1 kHz. The impact method was applied using 10 to 100 pulses to drill one hole. To produce holes of a proper diameter which could separate biological particles of a certain size (≥10 µm), optimum parameters of graphene paper laser ablation were defined using the MATLAB software taking into account laser pulse energy, repetition rate, and a desired hole diameter. A series of structural tests were carried out to determine the quality of an edge and a hole shape. Experimental results and Laguerre–Gauss calculations in MATLAB were then compared to perform the analysis of the distribution of diffraction fringes. Optimum experimental parameters were determined for which good susceptibility of the graphene paper to laser processing was observed. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study of the dynamic characteristics of the process of laser fragmentation/laser-induced fluorescence (LF/LIF) of trinitrotoluene traces on a paper surface under synchronized double-pulse laser irradiation. An Nd:YAG-laser (266 nm) was used for the fragmentation of TNT molecules, while fluorescence excitation of their NO fragments was performed using a KrF laser with a generation line of 247.867 nm in the region of the location of the bandhead of the P12 branch of the γ(0, 2) absorption band of the NO molecule. It was shown that the dissociation process of TNT traces has an inertial character and continues after the cessation of the fragmenting laser pulse. It was found that with the delay values between the fragmenting and probing laser pulses in the region of 200 ns, the efficiency of the LF/LIF method can be increased by 12 times. This paper presents the results of an experimental evaluation of the efficiency of two-pulse LF/LIF compared to single-pulse laser exposure, where the fragmentation of TNT molecules and excitation of their NO fragments were simultaneously performed by KrF laser pulses. The possibility of multiple increases in the efficiency of two-pulse LF/LIF with an increase in the energy density of the fragmenting laser radiation was shown. The obtained results are important in terms of increasing the sensitivity and/or range of the LF/LIF method for remote detection of traces of nitrocompounds. [ABSTRACT FROM AUTHOR]

In this paper, the growth of transverse-longitudinal coupled electromagnetic modes in the interaction of high-intensity lasers with dense plasma investigated. Using kinetic theory and solving the scattering relationship for the Vlasov-Maxwell system, the collision effects on the growth of the electromagnetic mode are studied. The anisotropic distribution function considers the effects of body stress due to laser ponderomotive force and plasma density gradient. The results show that a 99% reduction in frequency in the beam path in dense plasma leads to an 88% increase in unstable modes’ growth rate. Increasing the density prevents immediate cessation and enhances the growth of unstable modes. Increasing the density gradient by 99%, the instability rate maximum will increase by 88%. Overall, this paper provides insights into the effects of collision and anisotropic distribution function on the growth of transverse-longitudinal coupled electromagnetic modes in dense plasma. Overall, this paper provides insights into the interplay between various phenomena such as body stress, collision, and electromagnetic modes in dense plasma. [ABSTRACT FROM AUTHOR]

In this paper of I have reviewed the test done for validating the special theory of relativity using masers and lasers in last one century. Michelson-Morley did the first experimental verification for the isotropy of space for the propagation of light in 1887. It has an accuracy of 1/100th of a fringe shift. The predicted fringe shift on the basis of propagation of light through ether was 0.4 but Michelson-Morley did not observe any fringe shift and came up with a negative result. Their experiment was repeated with modern and more sophisticated versions using highly monochromatic masers and lasers which have kept any ether drag to the limit of < 1/1000th of the earth's orbital velocity and validated the isotropy of the space to the extraordinary limit of one part in 10[superscript15] . The necessary discussion on masers, lasers, its properties and applications with brief definition of beats is also given in this paper for the completeness of the discussion apart of the experimental method for validating the constant speed of light in different directions using masers and lasers.

This paper explores the pedagogy underpinning the use of laser manufacturing methods for the teaching of science, technology, engineering and mathematics (STEM) at key stage 3 design and technology. Clock making (horology) has been a popular project in design and technology (D&T) found in many schools, typically it focuses on aesthetical design elements. This paper describes a new project, which has been developed to enhance the STEM content of a horology project through advanced utilisation of laser cutting machinery. It allows pupils to produce their own products from self-made mechanical timing mechanisms. The central aim is to strengthen the application of the underlying technology of mechanisms and the manufacturing capability of laser cutting technology in D&T. Trials with schools have shown success in gaining pupils' interest in STEM and provided feedback to improve the project. It has highlighted limits when delivering the engineering and maths content with teachers from non-technology backgrounds. The paper discusses this limitation through subject pedagogy, categorisation of teacher knowledge, and teaching effectiveness through experiential and problem-based learning approaches.

The main goal of this study was to determine the reproducibility of the reading of wrist trauma case radiographs using three different media: laser film, a picture archiving and communication systems (PACS) workstation, and paper with an optimized layout. The study was conducted retrospectively in 200 consecutive patients consulting at the emergency department for wrist trauma and who underwent wrist X-ray investigation using a computed radiography system. There were 82 men and 118 women. The mean age was 48.3 years (16-95 years). Our institutional review board does not require patient approval or informed consent for retrospective review of case records. The readings were made by two independent readers who analyzed the 200 patient radiographs consecutively in one session for each type of media: paper, laser film, and on a PACS dual-screen workstation. The inter-reader agreements were substantial or almost perfect, with kappa values of 0.83 (0.76-0.90) for the PACS, 0.83 (0.76-0.90) for film, and 0.80 (0.72-0.87) for paper. The inter-technique agreement was almost perfect in all cases. There is a high interobserver agreement between PACS, laser film, and paper readings for wrist trauma cases. With a layout of one radiograph on each sheet, paper could replace laser films to communicate the results of wrist radiographs in trauma cases for outpatients. [ABSTRACT FROM AUTHOR]

In a long-distance wireless power transmission system with a non-uniform distribution of laser irradiation, it will significantly reduce the output power of the photovoltaic array, resulting in a large amount of power loss in the system and a decrease in conversion efficiency. This paper proposes an efficient and reliable optimal circuit connection algorithm for the 5 × 5 scale photovoltaic array. Under the laser illumination of 300 W, a 20 m wireless power transmission experiment was performed on four 5 × 5 scale photovoltaic arrays. The results show a 56.49% increase in the maximum output power of the 5 × 5 scale photovoltaic array. [ABSTRACT FROM AUTHOR]

Pavement adhesion plays a crucial role in driving safety, while traditional test methods exhibit some limitations. To improve the efficiency and accuracy of asphalt pavement texture characterization and adhesion assessments, this paper uses three-dimensional (3D) laser technology to detect the continuous point cloud data of road surface and reconstruct the 3D topography of pavement texture. On this basis, a volume parameter Volume of peak materials (Vmp) is innovatively proposed to comprehensively characterize the 3D spatial characteristics of road surface texture. The correlation analysis between the proposed Vmp and the traditional adhesion evaluation index Transversal Adhesion Coefficient (CAT) is conducted, and then refined graded adhesion prediction models based on the proposed Vmp are proposed. Results show that the proposed volume parameter Vmp can reliably and accurately characterize the asphalt pavement texture by considering more structural properties of the road surface texture. According to the research findings of this paper, it is feasible to achieve rapid and correct assessment of asphalt pavement adhesion using 3D laser detection technology by comprehensively considering the 3D characteristics of the road surface texture. [ABSTRACT FROM AUTHOR]

The split‐and‐delay unit (SDU) at FLASH2 will be upgraded to enable the simultaneous operation of two temporally, spatially and spectrally separated probe beams when the free‐electron laser undulators are operated in a two‐color scheme. By means of suitable thin filters and an optical grating beam path a wide range of combinations of photon energies in the spectral range from 150 eV to 780 eV can be chosen. In this paper, simulations of the spectral transmission and performance parameters of the filter technique are discussed, along with a monochromator with dispersion compensation presently under construction. [ABSTRACT FROM AUTHOR]