Longer Pulse Research Articles

Estimation of neutral beam injector power transferred to KSTAR plasmas

KSTAR shows the long pulse capability based on superconducting magnet and NBI plays a crucial role in sustaining the plasma via plasma heating and current driving. So, the accurate NBI power measurement transferred to KSTAR plasma is important for the analysis of plasma transport as well as plasma performance parameters. In a long pulse operation, the water coolant temperature is at the steady state condition in longer pulse more than 20s and the coupled neutral beam power to KSTAR plasma during the tokamak experiments is rechecked by using water flow calorimetric method after the experiment. The effect of beam duct scraper loss which was not considered at the neutral beam power calibration process is less than 5 % in terms of neutral beam power. However, in long pulse operation of NBI in KSTAR experiments, high strength of stray PF affects the beam path, the neutral beam power registered on mds + using beam current method is over estimated and it is calculated up to a few percent in terms of neutral beam power using calorimetric method. Therefore, it is necessary to consider the beam power variation by PF effect to interpret the plasma performance degradation in long pulse operation. Lastly. when the ion source tun on or turn off in condition other ion sources are operated, the beam transmission power is also affected because of sharing the beam box for ion sources so that the careful power estimation is necessary for such kind of beam power modulation experiments in KSTAR.

Terahertz Pseudo‐Waveform‐Selective Metasurface Absorber Based on a Square‐Patch Structure Loaded with Linear Circuit Components

In recent years, metasurfaces composed of lumped nonlinear circuits have been reported to exhibit the capability of detecting specific electromagnetic waves, even when the waves are of the same frequency, depending on their respective waveforms or, more precisely, their pulse widths. Herein, three types of metasurface absorbers (MSAs) are presented which are composed of a square‐patch structure loaded with linear circuit components, including lumped resistors or resistors in parallel with capacitors/inductors, which can mimic the waveform‐selective absorption behavior in the terahertz (THz) region. By judiciously selecting suitable values for the linear circuit components, these MSAs can achieve near‐perfect absorption of incident continuous waves or longer pulses while exhibiting reduced absorption of short pulses at the same THz frequency. These linear circuit structures can be referred to as pseudo‐waveform‐selective MSAs because their waveform‐selective absorption characteristics are primarily derived from the dispersion behavior of the resonator structures, as opposed to the frequency conversion commonly observed in nonlinear circuits. These outcomes and discoveries introduce an additional degree of freedom for waveform discrimination in the THz frequency range, potentially enabling a broader range of applications, including but not limited to detection, sensing, and wireless communication.

Crystalline Antimony Selenide Thin Films for Optoelectronics through Photonic Curing.

Thermal annealing is the most common postdeposition technique used to crystallize antimony selenide (Sb2Se3) thin films. However, due to slow processing speeds and a high energy cost, it is incompatible with the upscaling and commercialization of Sb2Se3 for future photovoltaics. Herein, for the first time, a fast-annealing technique that uses millisecond light pulses to deliver energy to the sample is adapted to cure thermally evaporated Sb2Se3 films. This study demonstrates how photonic curing (PC) conditions affect the outcome of Sb2Se3 phase conversion from amorphous to crystalline by evaluating the films' crystalline, morphological, and optical properties. We show that Sb2Se3 is readily converted under a variety of different conditions, but the zone where suitable films for optoelectronic applications are obtained is a small region of the parameter space. Sb2Se3 annealing with short pulses (<3 ms) shows significant damage to the sample, while using longer pulses (>5 ms) and a 4-5 J cm-2 radiant energy produces (211)- and (221)-oriented crystalline Sb2Se3 with minimal to no damage to the sample. A proof-of-concept photonically cured Sb2Se3 photovoltaic device is demonstrated. PC is a promising annealing method for large-area, high-throughput annealing of Sb2Se3 with various potential applications in Sb2Se3 photovoltaics.

Nimble vs. torpid responders to hydration pulse duration among soil microbes

Environmental parameters vary in time, and variability is inherent in soils, where microbial activity follows precipitation pulses. The expanded pulse-reserve paradigm (EPRP) contends that arid soil microorganisms have adaptively diversified in response to pulse regimes differing in frequency and duration. To test this, we incubate Chihuahuan Desert soil microbiomes under separate treatments in which 60 h of hydration was reached with pulses of different pulse duration (PD), punctuated by intervening periods of desiccation. Using 16S rRNA gene amplicon data, we measure treatment effects on microbiome net growth, growth efficiency, diversity, and species composition, tracking the fate of 370 phylotypes (23% of those detected). Consistent with predictions, microbial diversity is a direct, saturating function of PD. Increasingly larger shifts in community composition are detected with decreasing PD, as specialist phylotypes become more prominent. One in five phylotypes whose fate was tracked responds consistently to PD, some preferring short pulses (nimble responders; NIRs) and some longer pulses (torpid responders; TORs). For pulses shorter than a day, microbiome growth efficiency is an inverse function of PD, as predicted. We conclude that PD in pulsed soil environments constitutes a major driver of microbial community assembly and function, largely consistent with the EPRP predictions.

Efficient multiphoton microscopy with picosecond pulse trains

We present an all-fiber, portable setup for multiphoton microscopy with reduced frep employing a high-energy Yb:fiber NALM laser producing 10 ps pulses. Longer pulses are less susceptible to chromatic dispersion, enhancing image brightness and contrast over conventional femtosecond pulses.

Evaluation of the combustion process of directly injected methane in a rapid compression machine with a laser-based ignition system and an electrical ignition system

In order to reduce exhaust gas emissions, the application of lean operation in internal combustion engines has great potential. Experiments have been carried out in a rapid compression machine with directly injected methane comparing two laser ignition systems based on Nd:YAG lasers with an electrical ignition system. Three stratified extremely lean mixtures are ignited with up to 3 consecutive ignition pulses. This application-oriented investigation with the novel approach of combining laser ignition with a stratified charge in a rapid compression machine provides essential insights into the combustion process. The results highlight the advantages of laser ignition systems. The maximum pressure is increased by up to 9.5 %. The indicated work is increased by up to 16 % and cyclic variations are reduced by up to 35 %. The advantages increase as the mixture becomes leaner. A positive influence of multiple pulses can be observed as the ignition probability and the cyclic variations improve by up to 20 % per pulse and 25 % per pulse, respectively for the laser ignition. The evaluation shows that shorter pulse durations with a higher power achieve improved values for successful ignitions while longer pulses and a higher pulse energy achieve higher ignition probability values.

Influence of pulse width on the breakdown process of nanosecond pulse discharge at low pressure

Pulsed plasma discharge breakdown has long been a subject of research in the field of plasma physics. However, the spatial distribution and temporal evolution of parameters such as the density, energy, and electric field of charged particles during the breakdown process have not been thoroughly investigated. In this study, we investigate the breakdown process under nanosecond pulses with different pulse widths (1 ns, 10 ns, and 100 ns), utilizing the 1D implicit particle-in-cell/Monte Carlo collision method. Our simulation results indicate that pulse width plays a crucial role in the evolution of plasma breakdown. Specifically, under ultra-short pulses, the breakdown occurs after the pulse voltage ceases, demonstrating that increasing pulse width accelerates the changes in plasma parameters but does not affect the breakdown time. Under longer pulses, the removal of voltage leads to a significant increase in the thickness of the anode sheath. As the pulse width continues to increase, the ions collide in the cathode sheath after the pulse ends, resulting in ion energy loss. Finally, by scanning the parameter space, we give the Paschen curve and observe a higher breakdown voltage in the pulse case and the impact of ion secondary electrons.

In Pursuit of the Optimal Dusting Settings with the Thulium Fiber Laser: An In Vitro Assessment.

Objective: Low energy and high frequency settings are used in stone dusting for holmium lasers. Such settings may not be optimal for thulium fiber laser (TFL). With the seemingly endless combination of settings, we aim to provide guidance to the practicing urologists and assess the efficiency of the TFL platform in an automated in vitro "dusting model." Materials/Methods: Three experimental setups were designed to investigate stone dusting produced by an IPG Photonics TLR-50 W TFL system using 200 μm fiber and soft BegoStone phantoms. The most popular 10 and 20 W dusting settings among endourologist familiar with TFL were evaluated. We directly compared short pulse (SP) vs long pulse (LP) mode using various combinations of pulse energy (Ep) and pulse frequency (F). Thereafter, we tested the 10 and 20 W settings and compared them among each other to elucidate the most efficient settings at each power. Treatments were performed under the same total laser energy delivered to the stone at four different standoff distances (SDs) with a clinically relevant scanning speed of either 1 or 2 mm/sec. Ablation volumes were quantified by optical coherence tomography to assess stone dusting efficiency. Fragment size after ablation at different pulse energies was evaluated by sieving and evaluating under a microscope after treatment. Results: Overall, SP provided greater ablation volume when compared with LP. Our dusting efficiency model demonstrated that the maximum stone ablation was achieved at the combination of high energy/low frequency settings (p < 0.005) and at a SD of 0.2 mm. At all tested pulse energies, no stone phantoms were broken into fragments >1 mm. Conclusions: During stone dusting with TFL, SP offers superior ablation to LP settings. Optimal dusting at clinically relevant scanning speeds of 1 and 2 mm/sec occurs at high energy/low frequency settings. Thulium lithotripsy with high Ep does not result in increased fragment size.

MP26-19 CHARACTERIZATION OF THULIUM FIBER LASER PULSES: DIFFERENCES BETWEEN SHORT AND LONG PULSE

You have accessJournal of UrologyCME1 Apr 2023MP26-19 CHARACTERIZATION OF THULIUM FIBER LASER PULSES: DIFFERENCES BETWEEN SHORT AND LONG PULSE Ron Marom, William W. Roberts, Timothy L. Hall, John Robinson, Adam J. Matzger, and Khurshid R. Ghani Ron MaromRon Marom More articles by this author , William W. RobertsWilliam W. Roberts More articles by this author , Timothy L. HallTimothy L. Hall More articles by this author , John RobinsonJohn Robinson More articles by this author , Adam J. MatzgerAdam J. Matzger More articles by this author , and Khurshid R. GhaniKhurshid R. Ghani More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003254.19AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Recent studies have shown the significance of pulse modulation in energy delivery to the stone with better ablation and less retropulsion. Thulium Fiber Laser (TFL) is a novel laser technology with a different wavelength and pulse characteristics to holmium and is increasingly used for lithotripsy. Our aim was to characterize the TFL pulse to better understand parameter selection. METHODS: Using a commercially available TFL system (Fiber Dust, Quanta) we characterized the optical (temporal) profiles of a single pulse at 1J Shortest Pulse (SP), 1J Longest Pulse (LP), 3J SP, and 2.4 LP with a photo detector. By using MATLAB we normalized the optical profiles with the average pulse energy as measured by a power meter (n=100). We then performed high-speed imaging at 50,000 frames per second on the vapor bubble generated by pulses of 1J SP and 1J LP. Using MATLAB we segmented the bubble anatomy and measured its maximal width and length at each frame to quantify bubble dimensions. RESULTS: The temporal profile of the TFL pulse is rectangular in shape with a uniform power throughout the entire pulse besides a brief initial peak (<1% of the pulse energy). The full width half max (FWHM) for 1J SP, 1J LP, 3J SP, and 2.4J LP was calculated to be 2022.5 µsec, 5995 µsec, 6025 µsec, and 11990 µsec, respectively with a peak power governed by the pulse length: 474 Watts for SP and 167 Watts for LP (Figure 1). Both SP and LP of 1J reached the same maximal vapor bubble length of 4 mm, and the same maximal width of 1.8 mm. However, SP had intermittent closure of the channel while the LP channel appeared to elongate along the pulse duration (Figure 2). CONCLUSIONS: This study quantifies some of the single pulse characteristics of a TFL. In the system tested, the peak power was a function of the pulse duration and not the pulse energy. SP had multiple generations of bubble formation, almost like a multi-pulse, while LP had a channel shape that elongated and widened along the pulse duration. Further investigation is required to understand how these impact ablation. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e360 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ron Marom More articles by this author William W. Roberts More articles by this author Timothy L. Hall More articles by this author John Robinson More articles by this author Adam J. Matzger More articles by this author Khurshid R. Ghani More articles by this author Expand All Advertisement PDF downloadLoading ...

MP23-08 SHORT PULSE VS. LONG PULSE ABLATION WITH THE THULIUM FIBER LASER, AN IN VITRO STUDY

You have accessJournal of UrologyCME1 Apr 2023MP23-08 SHORT PULSE VS. LONG PULSE ABLATION WITH THE THULIUM FIBER LASER, AN IN VITRO STUDY Francois Soto Palou, Robert Medairos, Junqin Chen, Jodi Antonelli, Michael Lipkin, Glenn Preminger, and Pei Zhong Francois Soto PalouFrancois Soto Palou More articles by this author , Robert MedairosRobert Medairos More articles by this author , Junqin ChenJunqin Chen More articles by this author , Jodi AntonelliJodi Antonelli More articles by this author , Michael LipkinMichael Lipkin More articles by this author , Glenn PremingerGlenn Preminger More articles by this author , and Pei ZhongPei Zhong More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003248.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The thulium fiber laser (TFL) is becoming of interest to Urologists due to its unique properties. The TFL pulse profile consists of rectangular pulses, designed for enhancing photothermal ablation. Energy for each pulse may be modified by altering pulse duration or peak power. Our aim for this study is to compare short pulse (SP) versus long pulse (LP) for common 10 W dusting settings using the TFL platform. METHODS: All tests were conducted using an IPG Photonics TLR-50 W TFL system and a 200 μm fiber on “soft” (5:2) Begostone phantoms. The most popular 10 W dusting settings (Figure 1) among endourologists familiar with TFL were evaluated.[1] Four different standoff distances (0.2 mm, 0.5 mm 1 mm, 2 mm), and a clinically significant scanning speed of 1 mm/sec was used. The pulse profiles were altered for each energy setting to produce a short pulse (SP) and a long pulse (LP) design. The laser fiber was scanned in a 15 mm straight line with a 3D positioning system across a polished and submerged Begostone surface. Ablation volumes were quantified by optical coherence tomography (OCT). RESULTS: Overall, SP provided greater ablation volume when compared to LP. The greatest difference observed between SP and LP was at 1J/10 Hz and SD of 0.2 mm (2.51 mm3 vs. 0.35 mm3) and this difference was statistically significant (p<0.005). Out of the 20 performed trials there were only two instances in which LP outperformed SP in terms of ablation volume: 0.4J/25 Hz at SD of 2 mm (0 mm3 vs. 0.15 mm3) and 0.2J/50 Hz at SD of 0.2 mm (0.79 mm3 vs 0.81 mm3). In the latter case, however, the difference was not found to be statistically significant (p=0.7). CONCLUSIONS: TFL short pulse profile offers superior trough ablation volumes than long pulse during dusting under clinically relevant scanning speed of 1 mm/s with a time average power of 10 W. [1] Sierra A, Corrales M, Piñero A, Traxer O. Thulium fiber laser pre-settings during ureterorenoscopy: Twitter's experts' recommendations. World J Urol. 2022;40(6):1529-1535. doi:10.1007/s00345-022-03966-9. Source of Funding: N/A © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e308 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Francois Soto Palou More articles by this author Robert Medairos More articles by this author Junqin Chen More articles by this author Jodi Antonelli More articles by this author Michael Lipkin More articles by this author Glenn Preminger More articles by this author Pei Zhong More articles by this author Expand All Advertisement PDF downloadLoading ...

GOES’s domain structure in the vicinity and on the lines post-laser treatment

Pulsed laser processing for domain’s refinement is a recent technology implemented on an industrial scale. The present study focuses on the impact of different laser pulse durations on the magnetic properties such as total losses and domain structure of 0.28 mm thick grain-oriented electrical steel (GOES). Three pulse durations are considered Long Pulse (LP), Short-Pulse (SP) and Ultra-Short Pulse (USP). The latter has not been yet applied for domain refinement treatments, hence the interest of this research. Iron loss measured with the single sheet tester (SST) demonstrated a maximum loss reduction of 18 % at induction of 0.5 T and a frequency of 50 Hz following USP laser treatment. At a high induction of 1.7 T for the same frequency, both LP and USP pulse lengths achieved a reduction in total losses of 16 %. Moreover, the behaviour of the magnetic structure under laser treatment was detailed. The magnetic images were visualized by magneto-optical indicator film (MOIF). A reduction from 308 µm to 217 µm in the average domain size was observed post laser treatment with USP duration. Furthermore, the domain structure in the vicinity and on the laser line was investigated on a nanoscale using a magnetic force microscope (MFM). All these results confirmed the dependence of the laser-matter interaction on the laser pulse duration.

Development of an automated laser drilling algorithm to compare stone ablation patterns from different laser pulse modes.

To develop a novel automated three-dimensional (3D) laser drilling algorithm to further investigate laser-stone interaction with different laser pulse modes. Comparison of post-ablative lattice architecture combined with mass of stone ablated can provide a more complete understanding of differences between pulse mode. A 3D positioner (securing laser fiber) was programmed to create a 5 × 5 grid of drill holes spaced 1mm apart on 15:5 cylindrical BegoStones. Beginning 0.5mm above the stone surface, the laser fiber was activated and advanced 2mm toward and into the stone for all 25 points. Four trials for each pulse mode [short pulse (SP), long pulse (LP), Moses Contact (MC), Moses Distance (MD)] were completed. Outcome measures were assessment of lattice preservation and mass of ablated stone. MC exhibited the greatest lattice preservation and least stone mass ablated (50.5 ± 2.2mg). SP (69.4 ± 4.3mg) and MD (70.0 ± 2.6mg) had the greatest lattice destruction and stone mass ablated. The differences in stone ablated between MC and MD (p = 0.00003), MC and SP (p = 0.0002), and LP and MD (p = 0.004) were statistically significant. Consistent quantitative and qualitative differences between pulse modes were observed with a novel automated 3D laser drilling algorithm applied to BegoStone. The laser drilling algorithm developed here can be used to further enhance mechanistic understanding of laser-stone interactions and facilitate selection of appropriate laser pulse modes to balance precision and efficiency across the range of laser lithotripsy techniques.

Influence of CO2-laser pulse parameters on 13.5 nm extreme ultraviolet emission features from irradiated liquid tin target

A laser-produced plasma excited by CO2 laser pulses with various durations and energies on liquid tin droplets with diameters of 150 μm and 180 μm is considered. A two-dimensional radiative-magnetohydrodynamic code is used for numerical simulations of multicharged ion plasma radiation and dynamics. The code permits to understand the plasma dynamics self-consistent with radiation transport in non-local equilibrium multicharged ion plasma. Results of simulations for various laser pulse durations and 75 ÷ 600 mJ pulse energies with both Gaussian and experimentally taken temporal profiles are discussed. It is found that if the mass of the target is big enough to provide the plasma flux required (the considered case) a kind of dynamic quasi-stationary plasma flux is formed. In this dynamic quasi-stationary plasma flux, an interlayer of relatively cold tin vapor with mass density of 1 ÷ 2 g cm−3 is formed between the liquid tin droplet and low density plasma of the critical layer. Expanding of the tin vapor from the droplet provides the plasma flux to the critical layer. In critical layer the plasma is heated up and expands faster. In the simulation results with spherical liquid tin target, the conversion efficiency into 2π is of 4% for 30 ns full width half maximum (FWHM) and just slightly lower—of 3.67% for 240 ns FWHM for equal laser intensities of 14 GW cm−2. This slight decay of the in-band extreme ultraviolet (EUV) yield with laser pulse duration is conditioned by an increasing of radiation re-absorption by expanding plasma from the target, as more cold plasma is produced with longer pulse. The calculated angular distributions of in-band EUV emission permit to optimize a collector configuration.

Impact of Ultra-Short Pulsed Laser (USPL) Ablation Process on Separated Loss Coefficients of Grain Oriented Electrical Steels

The purpose of this article is to study the impact of surface laser treatments with ultra-short pulses (USPs) (femtosecond laser) on the magnetic properties of grain-oriented electrical steels (GOESs) using the two-temperature model for the ablation process and the magnetic loss separation model of Bertotti. We demonstrated that the hysteresis and excess loss coefficients behave differently depending on the type of laser treatment and its pulse duration [long pulse (LP), short pulses (SPs), and USP]. We also presented the adjusted models to estimate the impact of the USP on the sheet surface in terms of laser energetic quantities; more precisely, the groove depth, the plasma maximum temperature, and the peak surface wave pressure were estimated, relative to its nominal value. The latter physical impacts of laser pulses were then correlated with Bertotti’s loss coefficients: the static hysteresis loss coefficient and the excess loss coefficient. The laser process is not always able to reduce simultaneously both loss contributions. Thus, a compromise must be found to optimize the process. The variation of the flux density level as a function of the applied magnetic field was measured with a single sheet tester (SST) under a one-directional field parallel to the rolling direction. From these measurements, we deduced the whole power loss contributions. Results showed that an optimization of the laser’s parameters ensured an iron loss reduction at 50 Hz up to −30% for an induction below 0.5 T and a percentage close to −15% for an induction above 1.5 T.

Modulation of high-energy γ-rays by collision of an ultra-high-energy electron with a tightly focused circularly polarized laser pulse.

Using an ultra-high-energy (γ⩾1000) electron to collide with laser pulses to generate high-energy γ-rays is an important way to treat cancer. We investigate a method for modulating high-energy γ-rays with higher energy and more collimation using tightly focused circularly polarized laser pulses colliding with an ultra-high-energy electron. Theoretical derivation and numerical simulation within the framework of classical electrodynamics show that higher electron initial energy, stronger laser intensity, and a longer pulse can generate higher γ-ray energy. The high-energy γ-rays generated by an electron with higher initial energies are more collimated. The increase of the laser intensity and the increase of the pulse width will increase the angular range of the high-energy γ-rays. At the same time, the phenomenon of the "jumping point," in which the radiation energy varies with the laser intensity, was found. Our findings have important implications for modulating better high-energy γ-ray sources.

Laser ablation treatment of soiled featherworks: The first validation study

• Laser cleaning is effective and controllable to remove soiling from featherworks. • Feathers tested herein showed an unexpected high stability under laser irradiation. • In the optimal fluence range no relevant modifications were detected. • Longer pulses by Nd:YAG (1064 nm) laser provide a more gradual action than shorter ones. • With one laser treatment simultaneous cleaning on both sides of a feather is achieved. While laser treatments gradually spread in conservation, there is a growing interest on their application to the removal of soiling from fragile artefacts made of organic fibrous materials since direct and/or long term undesired effects have been observed when using traditional cleaning techniques. In this work, fiber-coupled Q-Switched (QS) and Long-Q-Switched (LQS) Nd:YAG (1064 nm) lasers were comparatively tested in order to define the restoration procedure of a heavily soiled 17th Brazil Tupinambà feathered cloak mostly made of scarlet ibis feathers. As assessed using fluorescence and Vis-NIR micro-spectroscopy, safe single-pulse removal thresholds were about 0.12 J/cm 2 for QS and 0.4 J/cm 2 for LQS, while microstructural damage was observed at 1 J/cm 2 and 5 J/cm 2 , respectively, thus evidencing a significant selectivity potential. Undesired effects were thoroughly investigated also considering the dependence on the pulse repetition frequency and number of pulses, in order to determine the optimum irradiation parameters in view of the extensive laser treatment of the present artefacts. Furthermore, analytical characterizations using SEM and contact-angle measurements allowed demonstrating that no any microstructural change occurred below the alteration fluences measured. According to these results, an overall laser-based dry cleaning methodology including laser ablation, paper sheets to collect removed soiling particles, and continuous particle suction by low pressure table and hoods was defined and successfully carried out. The laser-based restoration and associated systematic analytical characterizations of the present Brazil Tupinambà cloak represents the first validation study on laser ablation treatments in conservation of featherworks, which offered the opportunity to approach related general methodological aspects concerning the characterization of laser-induced effects, threshold definitions, and operative fluences.

Diffraction of strongly interacting molecular Bose-Einstein condensate from standing wave light pulses

We study the effects of strong inter-particle interaction on diffraction of a Bose-Einstein condensate of ^6\mathrm{Li}_26Li2 molecules from a periodic potential created by pulses of a far detuned optical standing wave. For short pulses we observe the standard Kapitza-Dirac diffraction, with the contrast of the diffraction pattern strongly reduced for very large interactions due to interaction-dependent loss processes. For longer pulses diffraction shows the characteristic for matter waves impinging on an array of tubes and coherent channeling transport. We observe a slowing down of the time evolution governing the population of the momentum modes caused by the strong atom interaction. A simple physical explanation of that slowing down is the phase shift caused by the self-interaction of the forming matter wave patterns inside the standing light wave. Simple 1D mean field simulations qualitatively capture the phenomenon, however to quantitatively reproduce the experimental results the molecular scattering length has to be multiplied by factor of 4.2. In addition, two contributions to interaction-dependent degradation of the coherent diffraction patterns were identified: (i) in-trap loss of molecules during the lattice pulse, which involves dissociation of Feshbach molecules into free atoms, as confirmed by radio-frequency spectroscopy and (ii) collisions between different momentum modes during separation. This was confirmed by interferometrically recombining the diffracted momenta into the zero-momentum peak, which consequently removed the scattering background.

PD37-07 THULIUM FIBER VS THULIUM YAG LASER EFFECT ON UPPER URINARY TRACT SOFT TISSUE: AN EX VIVO STUDY

You have accessJournal of UrologyCME1 May 2022PD37-07 THULIUM FIBER VS THULIUM YAG LASER EFFECT ON UPPER URINARY TRACT SOFT TISSUE: AN EX VIVO STUDY Luis Rico, Silvia Proietti, Maria Pia Pavia, Leandro Blas, Roberta Lucianò, Nazario Pio Tenace, Pablo Contreras, Andrea Benedetto Galosi, Franco Gaboardi, and Guido Giusti Luis RicoLuis Rico More articles by this author , Silvia ProiettiSilvia Proietti More articles by this author , Maria Pia PaviaMaria Pia Pavia More articles by this author , Leandro BlasLeandro Blas More articles by this author , Roberta LucianòRoberta Lucianò More articles by this author , Nazario Pio TenaceNazario Pio Tenace More articles by this author , Pablo ContrerasPablo Contreras More articles by this author , Andrea Benedetto GalosiAndrea Benedetto Galosi More articles by this author , Franco GaboardiFranco Gaboardi More articles by this author , and Guido GiustiGuido Giusti More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002595.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To date, there is a lack of evidence in terms of comparison of TFL and Tm:YAG laser on soft tissue. The aim of this study was to compare soft tissue effects of these 2 lasers at various settings, with a focus on incision depth (ID), coagulation (CA) and vaporization areas (VA). METHODS: We performed an ex-vivo study in a porcine model. The setup included a robotic arm that was holding the firing fiber laser while moving longitudinally, creating a fissure on the urothelium over a length of 1.5 cm. Two lasers were used: the 200 W Tm:YAG (CyberTM, Quanta System) in Continuous wave (CW) and the TFL laser (Fiber Dust, Quanta System) in CW and in Pulsed mode. The diameter of the laser fiber used was 272 mm in core. Experiments were performed at a fiber-to-tissue working distance of 0 and 1 mm. The emission Powers considered were 5, 10, 15, 20 W. For TFL in Pulsed mode, different settings for each power emission in Short Pulse (SP) and Long pulse (LP) modalities were evaluated: 0.05 J 100 Hz; 0.1 J 50 Hz; 0.5 J 10 Hz; 1 J 5 Hz 0.05 J 200 Hz; 0.1 J 100 Hz; 0.5 J 20 Hz; 1 J 10 Hz 0.05 J 300 Hz; 0.1 J 150 Hz; 0.5 J 30 Hz; 1 J 15 Hz 0.05 J 400 Hz; 0.1 J 200 Hz; 0.5 J 40 Hz; 1 J 20 Hz Hystological examination was performed evaluating the following parameters: CA, VA, ID. Experiments and measurements were repeated 3 times for each setting. RESULTS: A total number of 240 experiments were performed. Considering the same power, the mean ID was significantly deeper with pulsed TFL SP compared to the other laser/modalities at both distances (p <0.05). The CA and VA were larger with Tm:YAG at both distances in the majority of powers considered (Table 1). For each laser, higher is the power, deeper is the ID and greater are the VA and CA (p <0.001).TFL SP showed significantly deeper ID and larger CA and VA in the majority of settings compared to TFL LP (Table 2). CONCLUSIONS: TFL seams to be an efficient alternative to Tm:YAG for soft tissue treatment. Future in vivo studies are necessary to corroborate these findings. Source of Funding: No Source of Funding © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e641 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Luis Rico More articles by this author Silvia Proietti More articles by this author Maria Pia Pavia More articles by this author Leandro Blas More articles by this author Roberta Lucianò More articles by this author Nazario Pio Tenace More articles by this author Pablo Contreras More articles by this author Andrea Benedetto Galosi More articles by this author Franco Gaboardi More articles by this author Guido Giusti More articles by this author Expand All Advertisement PDF DownloadLoading ...

Cerebral Blood Flow and Oxygen Delivery in Aneurysmal Subarachnoid Hemorrhage: Relation to Neurointensive Care Targets

BackgroundThe primary aim was to determine to what extent continuously monitored neurointensive care unit (neuro-ICU) targets predict cerebral blood flow (CBF) and delivery of oxygen (CDO2) after aneurysmal subarachnoid hemorrhage. The secondary aim was to determine whether CBF and CDO2 were associated with clinical outcome.MethodsIn this observational study, patients with aneurysmal subarachnoid hemorrhage treated at the neuro-ICU in Uppsala, Sweden, from 2012 to 2020 with at least one xenon-enhanced computed tomography (Xe-CT) obtained within the first 14 days post ictus were included. CBF was measured with the Xe-CT and CDO2 was calculated based on CBF and arterial oxygen content. Regional cerebral hypoperfusion was defined as CBF < 20 mL/100 g/min, and poor CDO2 was defined as CDO2 < 3.8 mL O2/100 g/min. Neuro-ICU variables including intracranial pressure (ICP), pressure reactivity index, cerebral perfusion pressure (CPP), optimal CPP, and body temperature were assessed in association with the Xe-CT. The acute phase was divided into early phase (day 1–3) and vasospasm phase (day 4–14).ResultsOf 148 patients, 27 had underwent a Xe-CT only in the early phase, 74 only in the vasospasm phase, and 47 patients in both phases. The patients exhibited cerebral hypoperfusion and poor CDO2 for medians of 15% and 30%, respectively, of the cortical brain areas in each patient. In multiple regressions, higher body temperature was associated with higher CBF and CDO2 in the early phase. In a similar regression for the vasospasm phase, younger age and longer pulse transit time (lower peripheral resistance) correlated with higher CBF and CDO2, whereas lower hematocrit only correlated with higher CBF but not with CDO2. ICP, CPP, and pressure reactivity index exhibited no independent association with CBF and CDO2. R2 of these regressions were below 0.3. Lower CBF and CDO2 in the early phase correlated with poor outcome, but this only held true for CDO2 in multiple regressions.ConclusionsSystemic and cerebral physiological variables exhibited a modest association with CBF and CDO2. Still, cerebral hypoperfusion and low CDO2 were common and low CDO2 was associated with poor outcome. Xe-CT imaging could be useful to help detect secondary brain injury not evident by high ICP and low CPP.

Change in the surface state of the single-crystal germanium as a result of implantation with silver ions and annealing with light pulses

Single-crystal c-Ge plates implanted with Ag+ ions with an energy of E=30 keV, current density of the ion beam J = 5 μA/cm2 and a dose of D = 2.5· 1016 ion/cm2 were subjected to rapid thermal annealing by single light pulses of various durations from 1 up to 9.5 s. By scanning electron microscopy and optical reflection spectroscopy measurements it was shown that after ion implantation an amorphous porous Ag : PGe layer of spongy structure, consisting of Ge nanowires, is formed on the surface of c-Ge substrates. It was found that the annealing with an increase in the pulse duration up to 5 s successively leads to an increase in the Ge nanowire diameters from 26 to 35 nm. With longer pulses, the porous Ag : PGe structure is destroyed and Ag evaporates from the implanted layers. Keywords: nanoporous germanium, ion implantation, rapid thermal annealing.