Laser Ablation Research Articles

DLS homemade setup: reviewing first and second-order coherence and autocorrelation concepts of a light source in the context of nanoparticle sizes synthesized by PLAL

The size of the nanoparticles (NP) is one of the most important and essential characteristics to know the properties of the synthesized nanostructures. The most common characterization procedures are related to Scanning Electronic Microscopy (SEM), Transmission Electronic Microscopy (TEM), and Atomic Force Microscopy (AFM). Unfortunately, from a practical point of view, they represent a time-consuming procedure and require expensive equipment, which limits its application to specialized research groups. Significant attention has been paid to Dynamic Light Scattering (DLS) as a simple, fast, and reproducible method for sizing nanoparticles. However, inadequate representation of the fundamental principles of DLS and data interpretation represents two of the most important challenges related to this technique. In this work we try to provide the fundamental principles of the DLS technique, the fundamental mathematical treatment of data obtained during the optical scattering studies and provide the MATLAB code to configure non-commercial DLS equipment. Additionally, analyzes of nanoparticles obtained by pulsed laser ablation of Ag, Au, Si and W and commercial Au nanoparticles were carried out. The particle size results are compared with SEM images to calculate the percentage error of the DLS measurements. The results show an error of 5%, 3.8%, 2.1% for the Ag, Au and Si nanoparticles respectively, which proves to be an excellent approximation to the real values of nanoparticle diameter. Meanwhile, the error in size for W nanoparticles by the same technique and commercial Au nanoparticle is 29% and 12%, which shows the effect of the hydrodynamic diameter of the nanoparticles. This work ends with the analysis of the concentration of nanoparticles and its importance in reliable results of DLS measurements.

Theoretical Investigation of Laser Ablation Propulsion Using Micro-Scale Fluid in Atmosphere

Laser ablation propulsion based on liquid propellants is a type of propulsion technology with a high specific impulse and good controllability that can be applied to space thrusters, gas metal arc welding, and extreme ultraviolet light. However, its basic mechanisms, such as flow evolution and thrust formation, have not yet been described in detail. In this study, the laser ablation of micro-scale fluid in the atmosphere was investigated. Flow evolution with different laser energy and fluid mass was observed using a schlieren system. According to the characteristic of flow evolution, a theoretical model of laser ablation propulsion in the atmosphere was established. For the first time, a theoretical hypothesis was proposed that the laser energy is divided into two parts, which act on fluid and air respectively. The model indicates that the impulses generated by fluids and air follow power laws with the laser energy, while the exponentials are 0.5 and 1, respectively. In the atmosphere, due to the shielding effect of a laser-maintained detonation wave on laser, the energy absorbed by the fluid is basically unchanged, while only the energy absorbed by the air changes. Significantly, the theoretical model is consistent with the impulse experiment and current studies.

Enhancing Spectral Responsivity of Zinc Oxide Nanoparticles via Laser Ablation on Porous Silicon

Enhancing Spectral Responsivity of Zinc Oxide Nanoparticles via Laser Ablation on Porous Silicon

Breaking the vitrification limitation of monatomic metals.

The question of whether all materials can solidify into the glassy form proposed by Turnbull half a century ago remains unsolved. Some of the simplest systems of monatomic metals have not been vitrified, especially the close-packed face-centred cubic metals. Here we report the vitrification of gold, which is notoriously difficult to be vitrified, and several similar close-packed face-centred cubic and hexagonal metals using a method of picosecond pulsed laser ablation in a liquid medium. The vitrification occurs through the rapid cooling during laser ablation and the inhibition of nucleation by the liquid medium. Using this method, a large number of atomic configurations, including glassy configurations, can be generated simultaneously, from which a stable glass state can be sampled. Simulations demonstrate that the favourable stability of monatomic metals stems from the strong topological frustration of icosahedra-like clusters. Our work breaks the limitation of the glass-forming ability of matter, indicating that vitrification is an intrinsic property of matter and providing a strategy for the preparation and design of metallic glasses from an atomic configuration perspective.

Direct Three-Dimensional Mass Spectrometry Imaging with Laser Ablation Remote Atmospheric Pressure Photoionization/Chemical Ionization.

The laser ablation remote atmospheric pressure photoionization/chemical ionization (LARAPPI/CI) platform coupled to an ultrahigh resolution quadrupole-time-of-flight (QToF) mass spectrometer was developed and employed for the first direct three-dimensional (3D) mass spectrometry imaging (MSI) of metabolites in human and plant tissues. Our solution for 3D MSI does not require sample modification or cutting into thin slices. Ablation characteristics of an optical system based on a diffraction optical element are studied and used for voxel stacking to directly remove layers of tissues. Agar gel, red radish, kiwi, human kidney cancer, and normal tissue samples were used for the tests of this new system. The 2D and 3D ion images vividly illustrate differences in the abundances of selected metabolites between cancerous and noncancerous regions of the kidney tissue and also between different parts of plant tissues. The LARAPPI/CI MSI setup is also the first example of the successful use of combined dopant-assisted atmospheric pressure photoionization (DA-APPI) and atmospheric pressure chemical ionization (APCI) ion source for mass spectrometry imaging.

A Stereolithography-Based Modified Spin-Casting Method for Faster Laboratory-Scale Production of Dexamethasone-Containing Dissolving Microneedle Arrays.

Microneedle arrays (MNAs) consist of a few dozens of submillimeter needles, which tend to penetrate through the stratum corneum layer of the skin and deliver hardly penetrating drugs to the systemic circulation. The application of this smart dosage form shows several advantages, such as simple use and negligible pain caused by needle punctures compared to conventional subcutaneous injections. Dissolving MNAs (DMNAs) represent a promising form of cutaneous drug delivery due to their high drug content, biocompatibility, and ease of use. Although different technologies are suitable to produce microneedle arrays (e.g., micromilling, chemical etching, laser ablation etc.), many of these are expensive or hardly accessible. Following the exponential growth of the 3D-printing industry in the last decade, high-resolution desktop printers became accessible for researchers to easily and cost-effectively design and produce microstructures, including MNAs. In this work, a low force stereolithography (LFS) 3D-printer was used to develop the dimensionally correct MNA masters for the spin-casting method. The present study aimed to develop and characterize drug-loaded DMNAs using a two-level, full factorial design for three factors focusing on the optimization of DMNA production and adequate drug content. For the preparation of DMNAs, carboxymethylcellulose and trehalose were used in certain amounts as matrices for dexamethasone sodium phosphate (DEX). Investigation of the produced DexDMNAs included mechanical analysis via texture analyzer and optical microscopy, determination of drug content and distribution with HPLC and Raman microscopy, dissolution studies via HPLC, and ex vivo qualitative permeation studies by Raman mapping. It can be concluded that a DEX-containing, mechanically stable, biodegradable DexDMNA system was successfully developed in two dosage strengths, of which both efficiently delivered the drug to the lower layers (dermis) of human skin. Moreover, the ex vivo skin penetration results support that the application of DMNAs for cutaneous drug delivery can be more effective than that of a conventional dermal gel.

Release of ions enhanced the antibacterial performance of laser-generated, uncoated Ag nanoparticles

Identifying the antibacterial mechanisms of elemental silver at the nanoscale remains a significant challenge due to the intertwining behaviors between the particles and their released ions. The open question is which of the above factor dominate the antibacterial behaviors when silver nanoparticles (Ag NPs) with different sizes. Considering the high reactivity of Ag NPs, prior research has primarily concentrated on coated particles, which inevitably hinder the release of Ag+ ions due to additional chemical agents. In this study, we synthesized various Ag NPs, both coated and uncoated, using the laser ablation in liquids (LAL) technique. By analyzing both the changes in particle size and Ag+ ions release, the impacts of various Ag NPs on the cellular activity and morphological changes of gram-negative (E. coil) and gram-positive (S. aureus) bacteria were evaluated. Our findings revealed that for uncoated Ag NPs, smaller particles exhibited greater ions release efficiency and enhanced antibacterial efficacy. Specifically, particles approximately 1.5 nm in size released up to 55 % of their Ag+ ions within 4 h, significantly inhibiting bacterial growth. Additionally, larger particles tended to aggregate on the bacterial cell membrane surface, whereas smaller particles were more likely to be internalized by the bacteria. Notably, treatment with smaller Ag NPs led to more pronounced bacterial morphological changes and elevated levels of intracellular reactive oxygen species (ROS). We proposed that the bactericidal activity of Ag NPs stems from the synergistic effect between particle-cell interaction and the ionic silver, which is dependent on the crucial parameter of particle size.

Mechanism Analysis of Rock Vitrification by Strip Laser Scanning.

The process of casing the wellbore in oil and gas drilling consumes a significant amount of time and economic resources. High-energy laser rock fracturing, as an efficient and cost-effective new approach, holds the potential to create a glass-like casing by irradiating the rocks as an alternative to traditional casing. The mechanism behind the vitrification of rocks using laser irradiation, a key factor in achieving glassified casings, remains to be studied. This paper, based on experiments involving scanning sandstone with a line laser, investigates the mechanism of rock vitrification using numerical simulations and X-ray diffractometers. The results demonstrate that the sandstone surface is transformed into glass after laser scanning, with multiple scans and the application of high-speed airflow helping to reduce the formation of bubbles and other phenomena. Furthermore, the speed of laser scanning showed a negative correlation with the laser ablation depth, glass thickness, temperature diffusion rate, and temperature gradient. Based on these findings, a groundbreaking method is proposed for creating high-quality glass by moving the laser to scan the rocks multiple times, offering insights for research into laser-manufactured wellbore casings. Furthermore, this approach holds promising prospects for enhancing and embellishing the exterior of structures and for in situ environmental modifications on planetary surfaces and beyond.

Exploring the Growth Dynamics of Size-Selected Carbon Atomic Wires with In Situ UV Resonance Raman Spectroscopy.

Short carbon atomic wires, the prototypes of the lacking carbon allotrope carbyne, represent the fundamental 1D system and the first stage in carbon nanostructure growth, which still exhibits many open points regarding their growth and stability. An in situ UV resonance Raman approach is introduced for real-time monitoring of the growth of carbon atomic wires during pulsed laser ablation in liquid without perturbing the synthesis environment. Single-chain species' growth dynamics are tracked, achieving size selectivity by exploiting the peculiar optoelectronic properties of carbon wires and the tunability of synchrotron radiation. Diverse solvents are systematically explored, finding size- and solvent-dependent production rates linked to the solvent's C/H ratio and carbonization tendency. Carbon atomic wires' growth dynamics reveal a complex interplay between formation and degradation, leading to an equilibrium. Water, lacking in carbon atoms and reduced polyynes solubility, yields fewer wires with rapid saturation. Organic solvents exhibit enhanced productivity and near-linear growth, attributed to additional carbon from solvent dissociation and low relative polarity. Exploring the dynamics of the saturation regime provides new insights into advancing carbon atomic wires synthesis via PLAL. Understanding carbon atomic wires' growth dynamics can contribute to optimizing PLAL processes for nanomaterial synthesis.

It is not crystal clear: “nuances” in the selection of raw materials for Iron Age translucent glass revealed by chemical analyses of beads from central Italy

The Iron Age was a period of change, with many innovations in the glass-making technology. The chemical composition of the set of objects considered in the present study demonstrates the diversity of the raw materials used and the depth of knowledge about the manipulation of glass appearance in the eighth-sixth centuries BCE. The study was carried out using fibre optics reflection spectroscopy and portable X-ray fluorescence spectrometry at the museums’ premises to examine a large number of glass beads and preliminarily group them on the basis of their composition and spectral characteristics. In addition, a smaller set of selected samples was analysed by laser ablation inductively coupled plasma mass spectrometry to provide a comprehensive chemical characterisation of the material. The compositional data indicated that the samples belonged to the high magnesium and low magnesium glass compositional types. Only one sample was recognised as low magnesium medium potassium glass. Glasses within each group were made from different sands, suggesting different provenances. Some of the samples were suggested to be of local origin, while the others were interpreted as imported glass. Evidence of glass colouring, decolouring and recycling are also discussed.

Enhanced classification of pyrite generations based on mineral chemistry using uniform manifold approximation and projection (UMAP)

Trace element signatures are tracked to unravel the genetic history of ore deposits in several mineral systems. This is particularly true for pyrite, a ubiquitous component of many ore-forming systems, including orogenic gold deposits. Here, we critically compare the efficacy of utilizing Uniform Manifold Approximation and Projection (UMAP) versus Principal Component Analysis (PCA) as dimensionality reduction tools applied to a 31 element dataset collected using Laser Ablation Inductively Coupled Mass Spectrometry of pyrite grains from the Kibali gold district (Democratic Republic of Congo). Because of the non-linearity inherent to mineral chemistry and because of its superior preservation of local (distances within clusters) and global (separation between clusters) data relationships, the UMAP approach outperforms dimensionality reduction by PCA. We further present a workflow in which UMAP dimensionality reduction is followed by k-means clustering to guide the classification of pyrite generations in the Kibali case study. Validating this approach with trace elements and UMAP + k-means on a seed-by-seed petrography basis shows that the workflow significantly enhances the original pyrite classification, previously based on texture. This study thus emphasizes the utility of employing advanced statistical analysis methods to capture the intricate nature of pyrite formation. These findings will shape best practices for handling large multi-element datasets in pyrite mineral chemistry studies and are extrapolatable to other mineral systems in which trace element signatures are used to infer the conditions of ore deposit genesis.

Numerical Simulation and Experimental Investigation of Single-Point Picosecond Laser Ablation inside K9 Glass

K9 glass is a classical transparent material widely used in high-power optical systems due to its high-temperature resistance. However, the precision machining of K9 glass is difficult. The laser processing method, characterized by being non-contact, having a small heat-affected zone, and having high processing precision, is commonly employed for processing intricate structures. In this study, the vector diffraction model is employed to simulate the internal electric field inside the material when focused by objective lenses with varying numerical apertures. Furthermore, the temperature field is simulated. The simulation considered the nonlinear absorption of the material, the stretching of the focal dot due to spherical aberration, and the energy loss of the laser during the focusing process. The experiment indicated that the ablated area consists of numerous small, ablated dots and that multiple ablated areas emerged under an NA of 0.6. This study can provide valuable references for the research of the interaction between lasers and glass materials.

Evaluation of femtosecond-LA-ICP-TOFMS for multi-elemental mapping at cellular resolution of human-tissue from cancer patients

The characterization of the multi-elemental distributions within a thin tissue section of a liver metastasis from colorectal cancer patient after oxaliplatin-based chemotherapy, is critically evaluated using Ultraviolet Femtosecond Laser Ablation Inductively Coupled Plasma-Time of Flight Mass Spectrometry (UV-fs-LA-ICP-TOFMS). Different femtosecond laser ablation conditions, in terms of spot size and energy per pulse, were investigated to achieve proper ablation of the formalin-fixed paraffin-embedded tumor sections, while also trying to minimize the ablation of the glass substrate. Moreover, histological images of the tissues before and after the ablation processes were combined with UV-fs-LA-ICP-TOFMS elemental mapping to achieve multi-elemental spatial distributions at cellular level. For instance, spatial distributions of endogenous 31P, 56Fe, 63Cu and 64Zn analytes were determined within the thin tissue section. Furthermore, spatial distribution of elements such as 24Mg, 28Si, and 40Ca were employed to study glass substrate ablation during tissue analysis. Additional analytes, which might be partially associated to compounds employed on hematoxylin and eosin tissue staining processes, such as 23Na, 27Al, 32S, 39K, 79Br and 127I, were also detected. Finally, the accumulation of the oxaliplatin-based chemotherapy products in the stroma was confirmed from the spatial distribution of 196Pt ion signals within the tissue.

Photocatalytic activity for degradation of methylene blue dye-mediated nanocomposite-copper oxide/graphene oxide preparation from blood solution via hydrothermal method with laser irradiation

Blood solution contains an abundant supply of metals, natural polysaccharides, and protein. Copper oxide/graphene oxide nanocomposite (CuO/GO NCs) was created by the hydrothermal method of mixing a blood solution with copper nitrate (Cu2NO3) salt and graphene (G) material, followed by irradiation with a pulse laser ablation (PLA) (Nd-YAG) technique at 250 Mj, 532 nm, 5 cm, and 900 pulses. Paper filters were used to investigate the methylene blue (MB) dye degradation of CuO-GO NCs produced via the PLA process. The structure and optical properties of CuO-GO-NCs were studied and analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) images, transmission electron microscopy (TEM) images, and UV–visible spectra. CuO/GO NCs have a cubic shape with an average crystal size range of 11–52 nm, according to XRD research. An average particle size of 40 nm is created in the surface morphology investigated with FE-SEM, indicating the form of small grains in the nanoparticle. Inside cell morphology examined by TEM, a grain particle size of 40 nm is produced, suggesting that the nanoparticle has a tiny spherical form for CuO NPs, while the morphology of GO NPs has a nanosheet-like structure. CuO/GO NCs have an optical band edge value of 2.5 eV and a wavelength of 352 nm, according to the UV–visible spectrum. Using filter paper containing CuO/GO NCs, the degradation efficiency of MB dye after 50 min in the presence of ambient light in the environment was 99 %. This is a brand-new, rapid, and safe technique that has never been used before.

Rotational Spectroscopy as a Tool to Characterize Sweet Taste: The Study of Dulcin.

According to old theories of sweetness, the perception of sweet substances is closely linked to the arrangement of atoms within them. To assess the validity of these theories, we conducted an analysis of the structure of the artificial sweetener dulcin for the first time, utilizing microwave spectroscopy and a laser ablation source. These techniques have enabled the identification of two conformers, which are stabilized by an intramolecular hydrogen bond between the amino group and the phenyl ring. The observed conformations were examined in light of the Shallenberger-Acree-Kier molecular theory of sweet taste, and they align with the hypothesized criteria. Furthermore, the study illustrates how conformational relaxation can alter the equilibrium conformational distribution, resulting in the absence of certain conformers in the conformational landscape.

Comparison of Clinical Outcomes Based on Venous Clinical Severity Score and Venous Disability Score Assessment of Patients with Chronic Vein Insufficiency Underwent Endovenous Laser Ablation With Puncture Above The Knee And Below The Knee Techniques

Comparison of Clinical Outcomes Based on Venous Clinical Severity Score and Venous Disability Score Assessment of Patients with Chronic Vein Insufficiency Underwent Endovenous Laser Ablation With Puncture Above The Knee And Below The Knee Techniques

High efficiency laser ablation of gold thin film by 2.8 GHz intraburst repetition rate pulses

This work initially presents our progress in developing a 14 W all-polarization-maintaining (PM) Yb-doped fiber laser system. This system can generate bursts with a 2.8 GHz intra-burst repetition rate and offers flexibility in burst repetition rates, starting from 100 kHz. The laser produces pulse energies up to 210 nJ, which can be dechirped to approximately 650 fs. Subsequently, we utilized the developed laser in thin film gold processing. We sent up to 6.4 W and employed three different intraburst pulse configurations on a 100 nm-thick gold film coated on glass. We achieved a record gold removal efficiency of 125 μg/W.s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu \ ext{g}/\ ext {W.s}$$\\end{document} using ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document}5 nJ pulses. Moreover, we determined an ablation pulse energy threshold of approximately 1 nJ, representing the lowest pulse energy to the best of our knowledge.

Comparison of Clinical Outcomes Based on Venous Clinical Severity Score and Venous Disability Score Assessment of Patients with Chronic Vein Insufficiency Underwent Endovenous Laser Ablation With Puncture Above The Knee And Below The Knee Techniques

Background: Patients with chronic venous insufficiency (CVI) undergo a standard puncture below the knee to access the great saphenous vein (GSV) for endovenous laser ablation (EVLA). However, in some cases, getting a puncture below the knee is difficult; a puncture above the knee to access the incompetent saphenous vein is another option. Objective: This study compared CVI patients' clinical results after EVLA with below- and above-the-knee punctures. Material and Methods: This retrospective, single-centre cohort study compared clinical outcomes after two EVLA technical punctures (puncturing the GSV below- and above-knee). At all follow-up visits, clinical outcomes, closure rate, and complications were assessed. Result: This study has recruited 248 patients, with 132 patients in the below-knee group and 116 patients in the above-knee group. Similar clinical outcomes after the procedure were seen in both groups with improving of the Venous Clinical Severity Score (VCSS) and the Venous Disability Score (VDS) (p < 0.05). The closure rate in both groups was 97% (p = 0.595). Complications, including thrombosis, bruises and paresthesia did not show statistical significance between groups (p = 1.000, p = 0.101 and p = 0.667 respectively). Burn injury was absent in both groups. Conclusion: The EVLA for incompetence GSV using an above-knee puncture was safe and effective and should be considered as an alternative method if the below-knee puncture fails in Non Ulcer CVI patients. Keyword: Chronic Venous Insufficiency, Endovenous Laser Ablation, Great Saphenous Vein.

Chemical analysis of fragments of glass and ceramic ware from Tycho Brahe’s laboratory at Uraniborg on the island of Ven (Sweden)

In addition to his astronomical observations the famous Renaissance astronomer Tycho Brahe (1546–1601) was known also for his interest in alchemy. He equipped his castle Uraniborg on the island of Ven with a state-of-the-art alchemical laboratory when it was erected around 1580. After Brahe’s death Uraniborg was demolished upon a royal decree from 1601, a process which was completed around 1650. In the present study we have analysed four glass shards and one ceramic shard most likely from the alchemical laboratory and retrieved during an archaeological excavation in 1988–90. Cross sections of the shards have been analysed for 31 trace elements by Laser Ablation Inductively Coupled Plasma with Mass Spectrometry with the aim of detecting any traces of the chemical substances on the inside or outside of the shards used in the laboratory. Four of the elements found in excess on the exterior surfaces of the shards, Cu, Sb, Au, and Hg, are in accordance with the reconstructed recipes of the three Paracelsian medicines for which Brahe was famous—Medicamenta tria. This is the first experimental data casting light on the alchemical experiments that took place at Uraniborg 1580–1599.

Enhancing the Antibacterial Properties of Chitosan Coatings: Ag@Chitosan and Chitosan from Insects

In this study, the electrophoretic deposition (EPD) technique was used to prepare chitosan-based coatings with enhanced antibacterial activity suitable for bone implant applications. We designed, prepared, and compared the physico-chemical and biological properties of coatings obtained with commercial chitosan, chitosan enriched with silver nanoparticles, and chitosan obtained from insects. With the aim to consider the issue of sustainability, silver nanoparticles were directly prepared in the chitosan solution by laser ablation via a liquid technique, avoiding the use of chemicals and limiting the production of wastes. Moreover, a sustainable source of chitosan, such as Hermetia Illucens exuviae, was considered. The EPD process was optimized by adjusting parameters like voltage and deposition time to achieve ideal coating thickness and adhesion. The prepared films were characterized by spectroscopic and microscopic techniques such as SEM, XRD, and FTIR. Antimicrobial tests against E. coli and S. aureus revealed that silver nanoparticles enhanced the antibacterial properties of the polymer, whereas the biological evaluation using the WST8 test on MG63 human osteoblast-like cells showed that all coatings were non-toxic. Finally, chitosan obtained from insect showed comparable properties with respect to the commercial polymer, suggesting it could replace seafood-derived chitosan in biomedical applications, whereas the Ag@chitosan composite demonstrated superior antibacterial activity without compromising its biocompatibility.