Combination Of Laser Ablation Research Articles

Design of a smart sensor mesh for the measurement of pH in ostomy applications

A carbon-loaded polyethylene film was modified through a combination of laser ablation and electrochemical anodisation to yield a mechanically flexible yet electroanalytically sensitive mesh. A custom flavin derivative bearing a pendant phenol substituent was electropolymerised onto the substrate, and its electrochemical properties were investigated. The reversible flavin electrochemistry was retained (Ep = −0.374 V vs. Ag/AgCl, pH 7), and the peak position was found to shift by 60 mV/pH over a range covering pH 2.55 to pH 8.12. The stability of the resulting composite has been evaluated, and the analytical applicability towards the voltammetric measurement of pH in human urine was critically assessed.

Hybrid CdS nanowires/Si heterostructure photodetector fabricated by intense pulsed light assisted - laser ablation in liquid

Synthesis of CdS nanowires NWs by combined intense pulsed light (IPL) and pulsed laser ablation in liquid is demonstrated for the first time. An IPL source providing 3 ms duration pulses was used to assist the synthesis of CdS nanowires by 7 ns pulsed laser ablation of cadmium target in thiourea and CTAB solution. The results showed a small increase in optical energy band gap of CdS NWs and a decrease of the nanowires diameter from 50 to 40 nm after combining the IPL. The intensity of the photoluminescence emission peak located at 458 nm was doubled when the IPL combined laser ablation process. In addition the synthesized CdS nanowires showed single crystalline pure hexagonal wurtzite phase with decreased particles agglomeration and smaller particle size. Raman spectra were improved too by revealing sharp and shifted peaks at 293 and 585 cm−1. The figures of merit of hybrid n-CdSNWs/p-Si heterojunction photodetector namely responsivity and minority carrier lifetime were found to be improved remarkably after using IPL assisted laser ablation.

Identification of organic molecules with a laboratory prototype based on the Laser Ablation-CosmOrbitrap

In the Solar System, extra-terrestrial organic molecules have been found on cometary primitive objects, on Titan and Enceladus icy moons and on Mars. Identification could be achieved for simple organic species by remote sensing based on spectroscopic methods. However in situ mass spectrometry is a key technology to determine the nature of more complex organic matter. A large panel of mass spectrometers has already been developed for space exploration combining different types of analysers and ion sources. Up to now the highest mass resolution reached with a space instrument is 9000 at m/z 28 and corresponds to the DFMS-ROSINA instrument (Balsiger et al., 2007) dedicated to the study of the comet 67P/Churyumov-Gerasimenko's atmosphere and ionosphere, in a low pressure environment. A new concept of mass analyser offering ultra-high mass resolving power of more than 50,000 at m/z 56 (under high vacuum condition about 10−9 mbar) is currently being developed for space applications: the CosmOrbitrap (Briois et al., 2016), based on the Orbitrap™ technology.This work challenges the use of LAb-CosmOrbitrap, a space instrument prototype combining Laser Ablation ionisation and the CosmOrbitrap mass analyser, to identify solid organic molecules of relevance to the future space exploration. For this purpose a blind test was jointly organised by the JAXA-HRMS team (Japan Aerospace Exploration Agency-High Resolution Mass Spectrometry) and the CosmOrbitrap consortium. The JAXA team provided two organic samples, whereas the CosmOrbitrap consortium analysed them without prior information. Thanks to the high analytical performances of the prototype and our HRMS data post-processing, we successfully identified the two molecules as HOBt, hydroxybenzotriazole (C6H5N3O) and BBOT, 2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene (C26H26N2O2S), with a mass resolving power of, respectively, 123 540 and 69 219. The success of this blind test on complex organic molecules shows the strong potential of LAb-CosmOrbitrap for future space applications.

Enhanced laser surface ablation with an integrated photoacoustic imaging and high intensity focused ultrasound system

Combined laser and ultrasound treatments have been found to have synergistic effects, which may be of particular note in dermatology. We aim to investigate the potential of this technology for dermatology through in vitro and ex vivo experiments. In vitro tissue phantoms made of agar and tattoo ink and tattooed ex vivo chicken breast tissue were used. An integrated photoacoustic imaging and high intensity focused ultrasound (HIFU) system, using a 5-ns tunable OPO laser system and a 5 MHz HIFU transducer, was used to perform photoacoustic analysis to identify the optical contrast, and perform combined laser and ultrasound ablation. On the tissue phantoms, lines of ablation were created under various operating conditions. The samples were then quantified to determine the level of ablation. Same procedures were performed on the tattooed chicken breast tissue and the tattoo was removed by using combined laser and ultrasound. Ablation in the in vitro tissue phantoms was observed with properly synchronized laser and ultrasound while no ablation was found with either laser or ultrasound alone. Increases to the intensity or pulse duration of ultrasound caused an increase in ablation to the samples. The tattoo was removed from the ex vivo chicken breast using combined laser and ultrasound with a radiant exposure of 1.2 J/cm2 while laser and ultrasound alone were unable to remove the tattoo. We determined that by supplementing nanosecond laser pulses with ultrasound, ablation, and tattoo removal can be achieved at laser radiant exposures levels would otherwise be ineffective. The area of ablation can be adjusted through changes in the intensity and duration of the ultrasound burst with a constant laser intensity. Additionally, the system can be used to perform photoacoustic analysis of the tissue to estimate the relative optical absorbance at various available wavelengths, allowing for pretreatment analysis. Lasers Surg. Med. 9999:1-9, 2019. © 2019 Wiley Periodicals, Inc.

Rotational Spectrum of Saccharin: Structure and Sweetness.

We present the first high-resolution rotational study of the artificial sweetener saccharin. By combining laser ablation (LA), narrow- and broadband Fourier transform microwave techniques (FTMW), and supersonic expansions, we have transferred the solid of saccharin (mp 229 °C) to a supersonic jet and captured its rotational spectrum. The rotational constants were accurately determined by fitting more than 60 rotational transitions for the parent and 34S isotopic species in the 6.4-10.4 GHz frequency range. Experiment and complementary quantum-chemical calculations provide accurate geometrical parameters for saccharin, the first artificial sweetener investigated by high-resolution microwave spectroscopy. The detailed structural information extracted from the rotational and 14N nuclear quadrupole coupling constants provided useful data in the context of the old theories of sweetness.

Determination of the normal A2Π state in MgF with application to direct laser cooling of molecules.

We report high resolution electronic spectroscopy of cold magnesium monofluoride (MgF) molecules in the gas phase, which are created by a combination of laser ablation, chemical reaction, and 6 K helium buffer-gas cooling. Thanks to the sufficient population in the low-lying rotational states, the P, Q, and R branches in the electronic transition of the X2Σ+ to A2Π state are able to be measured unambiguously by in-cell absorption spectra. For the first time, we show that the A2Π state of MgF is actually a normal state, not an inverted one. The laser cooling relevant transitions X2Σ+v=0,1,N=1→A2Π1/2(v=0,J'=1/2) are also identified, along with the hyperfine structure of the X2Σ+(v = 0, N = 1) state. This study provides an important step for ongoing laser cooling experiments of MgF molecules.

Treatment of condyloma acuminatum using the combination of laser ablation and ALA-PDT.

Human papilloma virus (HPV) infection and condyloma acuminatum (CA) in the genital area often exist in extensive and multi-point fashion. Laser ablation combined with topical photodynamic therapy (PDT) is a feasible approach for genital CA but its effectiveness and limitations need to be evaluated. This single-arm prospective study consisted of 100 newly diagnosed CA cases of both sexes. All patients underwent laser ablation and then three times aminolaevulinic acid-based photodynamic therapy (ALA-PDT). The outcomes were evaluated and analyzed 3 months after the treatment. A total of 98 patients completed the study. Except for 6 patients (4 males and 2 females) showed some residual lesions other 92 patients (93.8%) showed complete cure. However, there were 18 patients (10 males and 8 females) showed new lesions near the treated areas. Although the HPV types of 18 patients before and after treatment were not completely consistent, 94.4% percent of patients (17/18) had the same HPV type as the primary lesion, which suggested that these late-onset CA might have latent infection or subclinical infection in the early stage of the disease but the length of the incubation period was longer. Combination approach is effective in treating genital CA and preventing CA recurrence. But its limitations need to be recognized as the late-onset CA might occur near the treated area. The treatment plan needs to be optimized for multiple genital CA lesions.

Quality of life and outcomes in patients with a large toxic adenoma undergoing laser ablation plus radioiodine vs lobectomy

Purpose: Patients with toxic adenomas (TAs) that are too large to undergo radioactive iodine (RAI) treatment aimed at resolving hyperthyroidism and/or relieving mechanical pressure symptoms are referred to surgery. This prospective study aimed to assess the outcomes of combining laser ablation (LA) plus RAI vs lobectomy to treat large TAs in terms of clinical efficacy and the health-related quality of life (HRQoL).Patients and methods: Patients with TAs of volumes greater than 20 mL and a calculated therapeutic activity exceeding 600 Mbq were randomly assigned to undergo LA + RAI (Group A) or lobectomy (Group B). The HRQoL was assessed using 12-item Short Form Health Survey questionnaire before and 6 months after treatment.Results: Twenty-seven patients entered the study. After completing treatment, patients in Group A showed a TA reduction by a mean of 68% compared to baseline. Two of 14 patients (14.3%) in Group A and 2 of 13 (15.4%) in Group B became subclinically hypothyroid, whereas the remaining patients were euthyroid. HRQoL significantly improved in both groups after treatment.Conclusions: For patients with large TAs, a combination of LA and RAI is a feasible alternative to surgery. Similar to surgery, LA + RAI resolves the mechanical discomfort induced by nodule pressure and effectively treats the hyperthyroidism. This procedure also avoids the potential complications associated with surgery while guaranteeing a similar HRQoL benefit.

The Multiple Hydrogen-Bonding Networks of Polyol Ribitol.

Conformational flexibility and non-covalent interactions determine the structure and activity of molecules in biological processes. In this work, the hydrogen bonding networks of the polyol ribitol have been determined for the first time using a combination of laser ablation and broadband rotational spectroscopy. Five conformations of ribitol have been identified, two with extended carbon chains and three with bent chains. All conformations are stabilized by sequential hydrogen bonding networks of either four or five intramolecular O-H⋅⋅⋅O bonds in a clockwise or counter-clockwise arrangement. The hydrogen bonding patterns are related to the extended or bent-chain conformations of ribitol, and involve 2OH-4OH or 2OH-5OH linkages, respectively. Interestingly, all hydrogen bonds wrap round the carbon backbone of ribitol rather than being located above or below it as it happens for other polyols and cyclic sugars.

Laser spectroscopic study on sinapic acid and its hydrated complex in a cold gas phase molecular beam

The S1 (ππ∗)-S0 electronic spectrum and the infrared spectrum in the OH stretching region of sinapic acid (SA) and its 1:1 complex with water (SA-H2O) are observed in a supersonically cooled molecular beam. Supersonically-cooled SA and SA-H2O complex are obtained by a combination of laser ablation with a newly developed pulsed channel nozzle. Both SA and SA-H2O exhibit sharp electronic spectra, and measurements of UV-UV hole-burning spectra and time-dependent density functional theory (TD-DFT) calculation indicate that the observed vibronic bands belong to two conformers, syn and anti, in both SA and the SA-H2O complex. The OH stretching vibrations are observed with IR-UV double resonance spectroscopy. A comparison of the observed IR spectrum and the DFT-calculated one indicates that SA-H2O has the structure in which a carboxylic (COOH) group and the water form a cyclic hydrogen (H)-bond. The OH stretch of COOH is red-shifted as large as 600 cm−1 in the complex. The S1 lifetime of SA at the zero-point energy level is obtained to be 1.9 ns. This S1 lifetime is shorter than the reported one of its ester derivative (methyl sinapate, MS (Dean et al., J. Am. Chem. Soc. 136 (2014) 1478–14795)) but is much longer than the para-substituted cinnamates, p-hydroxy methylcinnamate (p-HMC (Shimada et al., Phys. Chem. Chem. Phys. 14 (2012) 8999–9005)) and p-methoxy methylcinnamate (p-MMC (Miyazaki et al., J. Chem. Phys. 141 (2014) 244313)). A calculation at TD-DFT level indicates that this long lifetime of SA is due to that the 1nπ∗ state and the transition states along the trans → cis isomerization in S1 (ππ∗) are located much higher in energy than p-HMC and p-MMC. This may lead a main nonradiative channel of SA in the low energy region to be the multistep intersystem crossing to T1 (3ππ∗) via the 3nπ∗ state.

Analysis of plasma enhanced pulsed laser deposition of transition metal oxide thin films using medium energy ion scattering

In this study, plasma-enhanced pulsed laser deposition (PE-PLD), which is a novel variant of pulsed laser deposition that combines laser ablation of metal targets with an electrically-produced oxygen plasma background, has been used for the fabrication of ZnO and Cu2O thin films. Samples prepared using the PE-PLD process, with the aim of generating desirable properties for a range of electrical and optical applications, have been analysed using medium energy ion scattering. Using a 100 keV He+ ion beam, high resolution depth profiling of the films was performed with an analysis of the stoichiometry and interface abruptness of these novel materials. It was found that the PE-PLD process can create stoichiometric thin films, the uniformity of which can be controlled by varying the power of the inductively coupled plasma. This technique showed a high deposition rate of ∼0.1 nm s−1.

Laser-patterned metallic interconnections for all stretchable organic electrochemical transistors

We describe a process allowing the patterning of fully stretchable organic electrochemical transistors (OECTs). The device consists of an active stretchable area connected with stretchable metallic interconnections. The current literature does not provide a complete, simple and accurate process using the standard thin film microelectronic techniques allowing the creation of such sensors. An innovative patterning process based on the combination of laser ablation and thermal release tape ensures the fabrication of highly stretchable metallic lines – encapsulated in polydimethylsiloxane – from conventional aluminium tape. State-of-the-art stretchability up to 70% combined with ultra-low mOhms resistance is demonstrated. We present a photolithographic process to pattern the organic active area onto stretchable substrate. Finally the formulation of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) is tuned to achieve an OECT with a maximum stretchability of 38% while maintaining transconductance up to 0.35 mS and channel current as high as 0.2 mA.

Multiplex quantitative imaging of human myocardial infarction by mass spectrometry-immunohistochemistry.

Simultaneous assessment of a panel of protein markers is becoming essential in order to enhance biomarker research and improve diagnostics. Specifically, postmortem diagnostics of early myocardial ischemia in sudden cardiac death cases could benefit from a multiplex marker assessment in the same tissue section. Current analytical antibody-based techniques (immunohistochemistry and immunofluorescence) limit multiplex analysis usually to not more than three antibodies. In this study, mass spectrometry-immunohistochemistry (MS-IHC) was performed by combining laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with rare-metal-isotope-tagged antibodies as a technique for multiplex analysis of human postmortem myocardial tissue samples. Tissue sections with myocardial infarction were simultaneously analyzed for seven primary, rare-metal-isotope-tagged antibodies (troponin T, myoglobin, fibronectin, C5b-9, unphosphorylated connexin 43, VEGF-B, and JunB). Comparison between the MS-IHC approach and chromogenic IHC showed similar patterns in ionic and optical images. In addition, absolute quantification was performed by MS-IHC, providing a proportional relationship between the signal intensity and the local marker concentration in tissue sections. These data demonstrated that LA-ICP-MS combined with rare-metal-isotope-tagged antibodies is an efficient strategy for simultaneous testing of multiple markers and allows not only visualization of molecules within the tissue but also quantification of the signal. Such imaging approach has a great potential in both diagnostics and pathology-related research.

Laser Ablation-Aerosol Mass Spectrometry-Chemical Ionization Mass Spectrometry for Ambient Surface Imaging.

Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. Here, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inlet providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. The results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.

Torques and Forces in the Mitotic Spindle

During cell division, microtubules of the mitotic spindle segregate chromosomes by exerting forces on kinetochores, protein complexes on the chromosomes. The central question is what forces drive chromosome segregation. The current model for anaphase in human cells includes shortening of kinetochore fibers and separation of spindle poles. Both processes require kinetochores to be linked with the poles. By combining laser ablation, photoactivation and theoretical modeling, we show that kinetochores can separate without any attachment to one spindle pole (Vukusić et al., Dev Cell 2017). This separation requires the bridging fiber, which connects sister kinetochore fibers (Kajtez et al., Nat Commun 2016). Bridging microtubules in intact spindles slide apart together with kinetochore fibers, indicating strong crosslinks between them. Thus, sliding of microtubules in the bridging fibers drives pole separation and pushes kinetochore fibers apart to segregate chromosomes. In addition to forces, torques may also exist in the spindle, yet they have not been investigated. We show that the spindle is chiral, based on our finding that microtubule bundles follow a left-handed helical path, which cannot be explained by forces but rather by torques acting in the bundles (Novak et al., bioRxiv 167437). STED super-resolution microscopy, as well as confocal microscopy, of human spindles shows that the bundles have complex curved shapes. The average helicity of the bundles with respect to the spindle axis is 1.5 degrees/µm. To explain the observed shapes, we introduce a theoretical model for the balance of forces and torques acting in the spindle, and show that torque is required to generate the helical shapes. We conclude that torques, in addition to forces, exist in the spindle and determine its architecture.

Facet-Dependent Selective Adsorption of Mn-Doped α-Fe2O3 Nanocrystals toward Heavy-Metal Ions

Engineering exposed active facets by doping impurities can dramatically modify the morphology and physicochemical properties of nanocrystalline hematite. In the work described in this paper, through the combination of laser ablation in liquid and hydrothermal treatment techniques, faceted Mn-doped α-Fe2O3 nanocrystals (NCs) were prepared by adjusting the doping level of elemental Mn. With the increase of Mn doping level, the hematite crystal evolved sequentially from isotropic polyhedral nanoparticles (NPs) to {116}-faceted saucer-shaped nanosheets (NSs), and then to {001}-faceted hexagonal NSs. Electrochemical stripping tests revealed that the Mn-doped α-Fe2O3 NCs show a facet-dependent adsorption ability toward Pb(II), Cd(II), and Hg(II) heavy-metal ions; that is, {001}-faceted hexagonal NSs exhibit high and selective adsorption toward Pb2+ ions, while {116}-faceted saucer-shaped NSs present strong and selective adsorption toward Cd2+ and Hg2+ ions. Density functional theory (DFT) calculations found tha...

Oxygen isotope geochemistry of Laurentide ice-sheet meltwater across Termination I

We present a new method that quantifies the oxygen isotope geochemistry of Laurentide ice-sheet (LIS) meltwater across the last deglaciation, and reconstruct decadal-scale variations in the δ18O of LIS meltwater entering the Gulf of Mexico between ∼18 and 11 ka. We employ a technique that combines laser ablation ICP-MS (LA-ICP-MS) and oxygen isotope analyses on individual shells of the planktic foraminifer Orbulina universa to quantify the instantaneous δ18Owater value of Mississippi River outflow, which was dominated by meltwater from the LIS. For each individual O. universa shell, we measure Mg/Ca (a proxy for temperature) and Ba/Ca (a proxy for salinity) with LA-ICP-MS, and then analyze the same O. universa for δ18O using the remaining material from the shell. From these proxies, we obtain δ18Owater and salinity estimates for each individual foraminifer. Regressions through data obtained from discrete core intervals yield δ18Ow vs. salinity relationships with a y-intercept that corresponds to the δ18Owater composition of the freshwater end-member. Our data suggest that from 15.5 through 14.6 ka, estimated δ18Ow values of Mississippi River discharge from discrete core intervals range from −11‰ to −21‰ VSMOW, which is consistent with δ18O values from both regional precipitation and the low-elevation, southern margin of the LIS. During the Bølling and Allerød (14.0 through 13.3 ka), estimated δ18Ow values of Mississippi River discharge from discrete core intervals range from −22‰ to −38‰ VSMOW. These values suggest a dynamic melting history of different parts of the LIS, with potential contributions to Mississippi River outflow from both the low-elevation, southern margin of the LIS and high-elevation, high-latitude domes in the LIS interior that were transported to the ablation zone. Prior to ∼15.5 ka, the δ18Owater value of the Mississippi River was similar to that of regional precipitation or low-latitude LIS meltwater, but the Ba concentration in the Mississippi basin was affected by changes in weathering within the watershed, complicating Ba-salinity relationships in the Gulf of Mexico. After 13 ka, our data suggest Mississippi River outflow did not influence surface salinity above our Gulf of Mexico Orca Basin core site. Rather, we hypothesize that open ocean conditions prevailed as sea level rose and the paleoshoreline at the southern edge of North America retreated northward.

Microtubule Sliding within the Bridging Fiber Pushes Kinetochore Fibers Apart to Segregate Chromosomes

SummaryDuring cell division, mitotic spindle microtubules segregate chromosomes by exerting forces on kinetochores. What forces drive chromosome segregation in anaphase remains a central question. The current model for anaphase in human cells includes shortening of kinetochore fibers and separation of spindle poles. Both processes require kinetochores to be linked with the poles. Here we show, by combining laser ablation, photoactivation, and theoretical modeling, that kinetochores can separate without any attachment to one spindle pole. This separation requires the bridging fiber, a microtubule bundle that connects sister kinetochore fibers. Bridging fiber microtubules in intact spindles slide apart with kinetochore fibers, indicating strong crosslinks between them. We conclude that sliding of microtubules within the bridging fibers drives pole separation and pushes kinetochore fibers poleward by the friction of passive crosslinks between these fibers. Thus, sliding within the bridging fiber works together with the shortening of kinetochore fibers to segregate chromosomes.

Synthesis and characterization of silver vanadates thin films for photocatalytic applications

Silver vanadates thin films were deposited by a hybrid deposition system combining laser ablation and thermal evaporation. A high purity vanadium target was ablated using the third harmonic of a Nd:YAG laser whereas high purity silver pellets were evaporated. The as-deposited thin films were subjected to thermal treatments at 400°C to obtain crystalline films. For films without Ag amorphous V2O5 thin films were deposited and as the Ag is incorporated in the material different silver vanadates were obtained. The effect of the silver load on the composition, structure, optical properties, surface morphology and photocatalytic response of the deposited films was studied. The film composition, determined by X-ray photoelectron spectroscopy, reveals Ag contents from 5.5 to 18.9 at.%. The crystalline phases formed were identified by micro-Raman Spectroscopy; the results indicate the formation of three silver vanadates depending on the silver content. The morphology was observed using scanning electron microscopy, the filḿs surface changes from a smooth surface to belts covering the surface and finally Ag nanoparticles are observed at the higher Ag contens. Optical properties determined from UV–vis reveal the presence of the surface plasmon signal in films containing silver. The films were tested in the photocatalytic degradation of Malachite Green dye reaching maximum degradations degrees close to 53% under solar irradiation. Reactive species trapping experiments suggest that O2− produced by the O2 reduction via the photogenerated electrons drives the photodegradation mechanism.

In vitro evaluation of bactericidal effect of silver and gold-silver nanoparticles coated with silicon dioxide on Xanthomonas fragariae

ABSTRACTIn this work it was evaluated the bactericidal effect of silver and silver-gold nanoparticles coated with silicon dioxide on Xanthomonas fragariae. Nanoparticles were synthesized by combining laser ablation and chemical synthesis techniques. Irradiating the samples at the same wavelength where nanoparticles exhibit its maximum absorbance is possible to photo induce the bactericidal effect by detonating the surface plasmon resonance. The results showed that the minimum bactericidal concentration (MBC) of silver nanoparticles was 16 μM (referred to [AgNO3]) and for silver-gold nanoparticles were 32 μM (referred to [AgNO3-HAuCl4]) at 60 minutes of irradiation.