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https://www.readbyqxmd.com/read/28646864/femtosecond-laser-assisted-cataract-surgery-after-penetrating-keratoplasty-a-case-report
#1
Danmin Cao, Shiming Wang, Yong Wang
BACKGROUND: Cataract surgery after penetratingkeratoplasty (PKP) is often challenging due to changes in the integrity of the cornea caused by PKP. For example, corneal endothelial cell (CEC) loss and corneal edema commonly occur after traditional phacoemulsification cataract surgery in patients that previously had successful PKP. Recent studies have reported that femtosecond laser-assisted cataract surgery (FLACS) significantly reduces the need for ultrasound energy minimizing mechanical damage to the cornea and results in a reduction of CEC loss and corneal edema...
June 24, 2017: BMC Ophthalmology
https://www.readbyqxmd.com/read/28646186/magnetisation-switching-of-fept-nanoparticle-recording-medium-by-femtosecond-laser-pulses
#2
R John, M Berritta, D Hinzke, C Müller, T Santos, H Ulrichs, P Nieves, J Walowski, R Mondal, O Chubykalo-Fesenko, J McCord, P M Oppeneer, U Nowak, M Münzenberg
Manipulation of magnetisation with ultrashort laser pulses is promising for information storage device applications. The dynamics of the magnetisation response depends on the energy transfer from the photons to the spins during the initial laser excitation. A material of special interest for magnetic storage are FePt nanoparticles, for which switching of the magnetisation with optical angular momentum was demonstrated recently. The mechanism remained unclear. Here we investigate experimentally and theoretically the all-optical switching of FePt nanoparticles...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28644485/probing-the-early-stages-of-photoreception-in-photoactive-yellow-protein-with-ultrafast-time-domain-raman-spectroscopy
#3
Hikaru Kuramochi, Satoshi Takeuchi, Kento Yonezawa, Hironari Kamikubo, Mikio Kataoka, Tahei Tahara
Unveiling the nuclear motions of photoreceptor proteins in action is a crucial goal in protein science in order to understand their elaborate mechanisms and how they achieve optimal selectivity and efficiency. Previous studies have provided detailed information on the structures of intermediates that appear during the later stages (>ns) of such photoreception cycles, yet the initial events immediately after photoabsorption remain unclear because of experimental challenges in monitoring nuclear rearrangements on ultrafast timescales, including protein-specific low-frequency motions...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644239/effect-of-the-learning-curve-on-visual-and-refractive-outcomes-of-small-incision-lenticule-extraction
#4
Tommy C Y Chan, Alex L K Ng, George P M Cheng, Victor C P Woo, Jiamei Zhang, Yan Wang, Vishal Jhanji
PURPOSE: To investigate the effect of the learning curve for small-incision lenticule extraction during the first 2 years of experience. METHODS: Small-incision lenticule extraction was performed using the 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec) by the same surgeon. The initial 100 patients since the surgeon started operating independently were considered as group 1; the recent 100 patients were considered as group 2. The same laser settings and technique were used...
June 21, 2017: Cornea
https://www.readbyqxmd.com/read/28643771/dynamics-of-valence-shell-electrons-and-nuclei-probed-by-strong-field-holography-and-rescattering
#5
Samuel G Walt, Niraghatam Bhargava Ram, Marcos Atala, Nikolay I Shvetsov-Shilovski, Aaron von Conta, Denitsa Baykusheva, Manfred Lein, Hans Jakob Wörner
Strong-field photoelectron holography and laser-induced electron diffraction (LIED) are two powerful emerging methods for probing the ultrafast dynamics of molecules. However, both of them have remained restricted to static systems and to nuclear dynamics induced by strong-field ionization. Here we extend these promising methods to image purely electronic valence-shell dynamics in molecules using photoelectron holography. In the same experiment, we use LIED and photoelectron holography simultaneously, to observe coupled electronic-rotational dynamics taking place on similar timescales...
June 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28642477/probing-ultrafast-%C3%AF-%C3%AF-n%C3%AF-internal-conversion-in-organic-chromophores-via-k-edge-resonant-absorption
#6
T J A Wolf, R H Myhre, J P Cryan, S Coriani, R J Squibb, A Battistoni, N Berrah, C Bostedt, P Bucksbaum, G Coslovich, R Feifel, K J Gaffney, J Grilj, T J Martinez, S Miyabe, S P Moeller, M Mucke, A Natan, R Obaid, T Osipov, O Plekan, S Wang, H Koch, M Gühr
Many photoinduced processes including photosynthesis and human vision happen in organic molecules and involve coupled femtosecond dynamics of nuclei and electrons. Organic molecules with heteroatoms often possess an important excited-state relaxation channel from an optically allowed ππ* to a dark nπ* state. The ππ*/nπ* internal conversion is difficult to investigate, as most spectroscopic methods are not exclusively sensitive to changes in the excited-state electronic structure. Here, we report achieving the required sensitivity by exploiting the element and site specificity of near-edge soft X-ray absorption spectroscopy...
June 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28640577/laser-ablation-molecular-isotopic-spectrometry-for-molecules-formation-chemistry-in-fs-laser-ablated-plasmas
#7
Huaming Hou, Xianglei Mao, Vassilia Zorba, Richard E Russo
Recently, laser ablated molecular isotopic spectrometry (LAMIS) has expanded its capability to explore molecules formation mechanism in laser induced plasma in addition to isotope analysis. LAMIS is powerful tool for tracking the origination of atoms that involved in formation of investigated molecules by labeling atoms with its isotopic substitution. The evolutionary formation pathways of organic molecules, especially of C2 dimers and CN radicals, were frequently reported. However, very little is known about the formation pathways for metallic radicals and heterodimers in laser ablated plasma...
June 22, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28639668/a-strategy-for-fabrication-of-controllable-3d-pattern-containing-clusters-and-nanoparticles-inside-a-solid-material
#8
Qiuqun Chen, Hui Song, Fangteng Zhang, Hang Zhang, Yongze Yu, Zhi Chen, Rongfei Wei, Ye Dai, Jianrong Qiu
Directly controlling the growth process of clusters and nanoparticles is an effective way to tune their specific properties, which has been considered as a significant issue lying at the heart of nanotechnology. For technological applications, great strides have been made in the assembly of clusters and nanoparticles. However, controllable synthesis of clusters and nanoparticles inside a bulk solid-state medium remains a tremendous challenge, which is important for integrated devices. Here we report a strategy for space-selective control of elemental tellurium (Te) precipitation as clusters or nanoparticles in glass by femtosecond (fs) laser irradiation...
June 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28635955/corrigendum-double-flow-focused-liquid-injector-for-efficient-serial-femtosecond-crystallography
#9
Dominik Oberthuer, Juraj Knoška, Max O Wiedorn, Kenneth R Beyerlein, David A Bushnell, Elena G Kovaleva, Michael Heymann, Lars Gumprecht, Richard A Kirian, Anton Barty, Valerio Mariani, Aleksandra Tolstikova, Luigi Adriano, Salah Awel, Miriam Barthelmess, Katerina Dörner, P Lourdu Xavier, Oleksandr Yefanov, Daniel R James, Garrett Nelson, Dingjie Wang, George Calvey, Yujie Chen, Andrea Schmidt, Michael Szczepek, Stefan Frielingsdorf, Oliver Lenz, Edward Snell, Philip J Robinson, Božidar Šarler, Grega Belšak, Marjan Maček, Fabian Wilde, Andrew Aquila, Sébastien Boutet, Mengning Liang, Mark S Hunter, Patrick Scheerer, John D Lipscomb, Uwe Weierstall, Roger D Kornberg, John C H Spence, Lois Pollack, Henry N Chapman, Saša Bajt
This corrects the article DOI: 10.1038/srep44628.
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28634405/shedding-new-light-on-an-old-molecule-quinophthalone-displays-uncommon-n-to-o-excited-state-intramolecular-proton-transfer-esipt-between-photobases
#10
Gi Rim Han, Doyk Hwang, Seunghoon Lee, Jong Woo Lee, Eunhak Lim, Jiyoung Heo, Seong Keun Kim
Excited state dynamics of common yellow dye quinophthalone (QPH) was probed by femtosecond transient absorption spectroscopy. Multi-exponential decay of the excited state and significant change of rate constants upon deuterium substitution indicate that uncommon nitrogen-to-oxygen excited state intramolecular proton transfer (ESIPT) occurs. By performing density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations, we found that adiabatic surface crossing between the S1 and S2 states takes place in the photoreaction...
June 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28630909/dynamic-fracture-of-tantalum-under-extreme-tensile-stress
#11
Bruno Albertazzi, Norimasa Ozaki, Vasily Zhakhovsky, Anatoly Faenov, Hideaki Habara, Marion Harmand, Nicholas Hartley, Denis Ilnitsky, Nail Inogamov, Yuichi Inubushi, Tetsuya Ishikawa, Tetsuo Katayama, Takahisa Koyama, Michel Koenig, Andrew Krygier, Takeshi Matsuoka, Satoshi Matsuyama, Emma McBride, Kirill Petrovich Migdal, Guillaume Morard, Haruhiko Ohashi, Takuo Okuchi, Tatiana Pikuz, Narangoo Purevjav, Osami Sakata, Yasuhisa Sano, Tomoko Sato, Toshimori Sekine, Yusuke Seto, Kenjiro Takahashi, Kazuo Tanaka, Yoshinori Tange, Tadashi Togashi, Kensuke Tono, Yuhei Umeda, Tommaso Vinci, Makina Yabashi, Toshinori Yabuuchi, Kazuto Yamauchi, Hirokatsu Yumoto, Ryosuke Kodama
The understanding of fracture phenomena of a material at extremely high strain rates is a key issue for a wide variety of scientific research ranging from applied science and technological developments to fundamental science such as laser-matter interaction and geology. Despite its interest, its study relies on a fine multiscale description, in between the atomic scale and macroscopic processes, so far only achievable by large-scale atomic simulations. Direct ultrafast real-time monitoring of dynamic fracture (spallation) at the atomic lattice scale with picosecond time resolution was beyond the reach of experimental techniques...
June 2017: Science Advances
https://www.readbyqxmd.com/read/28630409/two-dimensional-fluorescence-spectroscopy-of-uranium-isotopes-in-femtosecond-laser-ablation-plumes
#12
Mark C Phillips, Brian E Brumfield, Nicole LaHaye, Sivanandan S Harilal, Kyle C Hartig, Igor Jovanovic
We demonstrate measurement of uranium isotopes in femtosecond laser ablation plumes using two-dimensional fluorescence spectroscopy (2DFS). The high-resolution, tunable CW-laser spectroscopy technique clearly distinguishes atomic absorption from (235)U and (238)U in natural and highly enriched uranium metal samples. We present analysis of spectral resolution and analytical performance of 2DFS as a function of ambient pressure. Simultaneous measurement using time-resolved absorption spectroscopy provides information on temporal dynamics of the laser ablation plume and saturation behavior of fluorescence signals...
June 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28630331/distinguishing-attosecond-electron-electron-scattering-and-screening-in-transition-metals
#13
Cong Chen, Zhensheng Tao, Adra Carr, Piotr Matyba, Tibor Szilvási, Sebastian Emmerich, Martin Piecuch, Mark Keller, Dmitriy Zusin, Steffen Eich, Markus Rollinger, Wenjing You, Stefan Mathias, Uwe Thumm, Manos Mavrikakis, Martin Aeschlimann, Peter M Oppeneer, Henry Kapteyn, Margaret Murnane
Electron-electron interactions are the fastest processes in materials, occurring on femtosecond to attosecond timescales, depending on the electronic band structure of the material and the excitation energy. Such interactions can play a dominant role in light-induced processes such as nano-enhanced plasmonics and catalysis, light harvesting, or phase transitions. However, to date it has not been possible to experimentally distinguish fundamental electron interactions such as scattering and screening. Here, we use sequences of attosecond pulses to directly measure electron-electron interactions in different bands of different materials with both simple and complex Fermi surfaces...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28629164/cataract-surgery-performed-by-high-frequency-ldv-z8-femtosecond-laser-safety-efficacy-and-its-physical-properties
#14
Bojan Pajic, Zeljka Cvejic, Brigitte Pajic-Eggspuehler
BACKGROUND: The aim of our study was to investigate the safety and efficacy of the LDV Z8 femtosecond laser in cataract surgery compared to the conventional procedure. METHODS: This prospective study was performed at the Swiss Eye Research Foundation, Eye Clinic ORASIS, Reinach, Switzerland. The study included 130 eyes from 130 patients: 68 treated with femtosecond laser-assisted cataract surgery (FLACS) using the FEMTO LDV Z8 and 62 treated with conventional phacoemulsification...
June 18, 2017: Sensors
https://www.readbyqxmd.com/read/28628320/dynamics-of-charge-injection-and-charge-recombination-in-dna-mini-hairpins
#15
Ashutosh Kumar Mishra, Michelle A Harris, Ryan M Young, Michael R Wasielewski, Frederick D Lewis
Steady state spectroscopy, femtosecond transient absorption spectroscopy (fsTA), and femtosecond stimulated Raman spectroscopy (FSRS) of DNA mini-hairpins possessing a diphenylacetylenedicarboxamide (DPA) linker and 1-3 adenine-thymine (A-T) or guanine-cytosine (G-C) base pairs have been investigated. Ultraviolet and circular dichroism (UV and CD) spectra are consistent with ground state conformations that are predominantly base-paired and -stacked for conjugates possessing two or three base pairs; however, they offer no information concerning the conformation of conjugates possessing a single base pair...
June 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28628129/high-speed-fixed-target-serial-virus-crystallography
#16
Philip Roedig, Helen M Ginn, Tim Pakendorf, Geoff Sutton, Karl Harlos, Thomas S Walter, Jan Meyer, Pontus Fischer, Ramona Duman, Ismo Vartiainen, Bernd Reime, Martin Warmer, Aaron S Brewster, Iris D Young, Tara Michels-Clark, Nicholas K Sauter, Abhay Kotecha, James Kelly, David J Rowlands, Marcin Sikorsky, Silke Nelson, Daniel S Damiani, Roberto Alonso-Mori, Jingshan Ren, Elizabeth E Fry, Christian David, David I Stuart, Armin Wagner, Alke Meents
We report a method for serial X-ray crystallography at X-ray free-electron lasers (XFELs), which allows for full use of the current 120-Hz repetition rate of the Linear Coherent Light Source (LCLS). Using a micropatterned silicon chip in combination with the high-speed Roadrunner goniometer for sample delivery, we were able to determine the crystal structures of the picornavirus bovine enterovirus 2 (BEV2) and the cytoplasmic polyhedrosis virus type 18 polyhedrin, with total data collection times of less than 14 and 10 min, respectively...
June 19, 2017: Nature Methods
https://www.readbyqxmd.com/read/28627744/femtosecond-charge-injection-dynamics-at-hybrid-perovskite-interfaces
#17
Giulia Grancini, Daniele Viola, Yonghui Lee, Michael Saliba, Sanghyun Paek, Kyung Taek Cho, Simonetta Orlandi, Marco Cavazzini, Fernando Fungo, Mohammad I Hossain, Abdelhak Belaidi, Nouar Tabet, Gianluca Pozzi, Giulio Cerullo, Mohammad Khaja Khaja Nazeeruddin
With power conversion efficiency (PCE) exceeding 22%, perovskite solar cells (PSCs) have thrilled the photovoltaic research. However, interface behavior is still not understood and a hot subject of research: different processes occur over a hierarchy of timescales, from femtoseconds to seconds, making the perovskite interface physics intriguing. Here, by femtosecond transient absorption spectroscopy with spectral coverage extended to the crucial IR region, we interrogate the ultrafast interface- specific processes at standard as well as newly molecularly-engineered perovskite interfaces used in state of the art PSCs...
June 19, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28625052/photochemical-kinetics-of-a-phosphine-oxide-free-radical-initiator-from-femtosecond-uv-pump-mid-ir-probe-spectroscopy
#18
Steffen Straub, Joerg Lindner, Peter Vohringer
Femtosecond UV-pump/mid-infrared-probe spectroscopy was used to explore in detail the primary photochemical events of the free radical initiator, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, in liquid dichloromethane solution at room temperature. Following electronic excitation of its lowest excited singlet state, S1, the radical initiator undergoes an intersystem crossing to the triplet ground state, T1, with a time constant of 135 ps. A subsequent α-cleavage occurs from the triplet state with a time constant of 15 ps and yields a trimethylbenzoyl radical together with a diphenylphosphinoyl radical...
June 18, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28622316/corneal-densitometry-after-photorefractive-keratectomy-laser-assisted-in-situ-keratomileusis-and-small-incision-lenticule-extraction
#19
F Poyales, N Garzón, J Mendicute, I Illarramendi, P Caro, O Jáñez, F Argüeso, A López
PurposeThe aim of this study was to gain greater insight into the corneal densitometry changes occurring as a result of refractive surgery and to compare these changes across three widely used surgical techniques, namely, photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis with a femtosecond laser (LASIK-FS), or ReLEx small-incision lenticule extraction (ReLEx SMILE).Patients and methodsThree hundred and thirty-six patients (184 male and 152 female patients) participated in this study. They were split into three groups according to the refractive surgery technique they had undergone: LASIK-FS (74 patients), PRK (153 patients), and ReLEx SMILE (109 patients)...
June 16, 2017: Eye
https://www.readbyqxmd.com/read/28621306/targeted-two-photon-chemical-apoptotic-ablation-of-defined-cell-types-in-vivo
#20
Robert A Hill, Eyiyemisi C Damisah, Fuyi Chen, Alex C Kwan, Jaime Grutzendler
A major bottleneck limiting understanding of mechanisms and consequences of cell death in complex organisms is the inability to induce and visualize this process with spatial and temporal precision in living animals. Here we report a technique termed two-photon chemical apoptotic targeted ablation (2Phatal) that uses focal illumination with a femtosecond-pulsed laser to bleach a nucleic acid-binding dye causing dose-dependent apoptosis of individual cells without collateral damage. Using 2Phatal, we achieve precise ablation of distinct populations of neurons, glia and pericytes in the mouse brain and in zebrafish...
June 16, 2017: Nature Communications
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