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Meng Zhou, Chenjie Zeng, Matthew Y Sfeir, Mircea Cotlet, Kenji Iida, Katsuyuki Nobusada, Rongchao Jin
Understanding the correlation between the atomic structure and optical properties of gold nanoclusters is essential for exploration of their functionalities and applications involving light harvesting and electron transfer. Here, we report the femto-nanosecond excited state dynamics of a periodic series of face-centered cubic (FCC) gold nanoclusters (including Au28, Au36, Au44, and Au52), which exhibit a set of unique features compared to other similar sized clusters. Molecular-like ultrafast Sn→S1 internal conversions (i...
August 10, 2017: Journal of Physical Chemistry Letters
Mohamed Hosny, Fayrouz Aboalazayem, Hoda El Shiwy, Mohsen Salem
PURPOSE: The purpose of the study was to determine the accuracy of intraocular pressure (IOP) measurement after small incision lenticule extraction (SMILE) using Goldmann applanation tonometry (GAT) and ocular response analyzer (ORA). METHODS: This is a prospective clinical study that was conducted on 30 eyes in the interval between February 2016 and September 2016. The age of the patients ranged between 19 and 40 years. The patients underwent SMILE surgery using the femto laser...
2017: Clinical Ophthalmology
Maximilian Wolf, Astrid Herrmann, Andreas Hirsch, Dirk M Guldi
Porphyrin arrays consisting of three peripheral Zinc porphyrins (ZnPs) and a central free base porphyrin (H2P)-all rigidly linked to each other-serve as light-harvesting antennas as well as electron donors and are flexibly coupled to an electron-accepting C60 to realize the unidirectional flow of (i) excited-state energy from the ZnPs at the periphery to the H2P, (ii) electrons to C60, and (iii) holes to H2P and, subsequently, to ZnP. Dynamics following photoexcitation are elucidated by time-resolved transient absorption measurements on the femto-, pico-, nano-, and microsecond time scales and are examined by multiwavelength as well as target analyses...
August 15, 2017: Journal of the American Chemical Society
Weiwei Xu, Ye Tao, Liqiang Wang, Yifei Huang
BACKGROUND Some myopia patients with unsatisfactory corneas consider corneal refractive surgery for different reasons. Accelerated corneal collagen crosslinking (ACXL) is an effective method to enhance the resistance of the cornea. The present investigation was designed to evaluate the changes of biomechanical properties in patients with myopia and thin corneas after femtosecond-laser in situ keratomileusis (FS-LASIK) concurrent with ACXL. MATERIAL AND METHODS A prospective study was designed. A total of 22 eyes of 11 myopia astigmatism patients with unsatisfactory corneas were enrolled...
July 27, 2017: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
Majdi Hochlaf
Investigations of the spectroscopy and dynamics of small- and medium-sized molecules and clusters represent a hot topic in atmospheric chemistry, biology, physics, atto- and femto-chemistry and astrophysics. Nowadays, outstanding developments, both theoretical and experimental, have been achieved. The most recent results of these achievements are reviewed here. These molecular systems are studied by means of high-resolution spectroscopic techniques in either the frequency or the time domains. However, they still represent complex molecular systems since they may undergo processes that are still not fully understood in sufficient details...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Sri Ganesh, Sheetal Brar, Archana Pawar
PURPOSE: To compare toric implantable collamer lens (T-ICL), femto-LASIK, and ReLEx SMILE for the treatment of low to moderate myopic astigmatism in terms of long-term visual and refractive outcomes and predictability of astigmatic correction. MATERIALS AND METHODS: The study included 30 eyes from 30 patients between the age groups of 21 and 40 years, undergoing bilateral surgery with any of the three procedures - T-ICL, femto-LASIK, or ReLEx SMILE - for correction of myopic astigmatism within the range of -3 to -8 D spherical equivalent (SE), with a minimum astigmatism of -0...
2017: Clinical Ophthalmology
Vadim Kovalyuk, Simone Ferrari, Oliver Kahl, Alexander Semenov, Michael Shcherbatenko, Yury Lobanov, Roman Ozhegov, Alexander Korneev, Nataliya Kaurova, Boris Voronov, Wolfram Pernice, Gregory Gol'tsman
While single photon detectors provide superior intensity sensitivity, spectral resolution is usually lost after the detection event. Yet for applications in low signal infrared spectroscopy recovering information about the photon's frequency contributions is essential. Here we use highly efficient waveguide integrated superconducting single-photon detectors for on-chip coherent detection. In a single nanophotonic device, we demonstrate both single-photon counting with up to 86% on-chip detection efficiency, as well as heterodyne coherent detection with spectral resolution f/∆f exceeding 10(11)...
July 6, 2017: Scientific Reports
D J Aschaffenburg, X Chen, T Cuk
During photocatalytic water oxidation, n-SrTiO3(100) demonstrated near 100% Faradaic efficiency for O2 evolution with nano- (30 ns) and femto- (150 fs) second pulsed laser excitation of the band gap, despite surface rearrangements attributed to the high peak power (300 MW cm(-2)). Therefore, these results establish a methodology for tracking intermediates of the water oxidation cycle at the n-SrTiO3(100) surface from the picosecond time scales of charge transfer through to the millisecond time scales of O2 evolution...
June 29, 2017: Chemical Communications: Chem Comm
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
A Blériot, E Martin, P Lebranchu, K Zimmerman, L Libeau, M Weber, B Vabres, I Orignac
The management of severe keratoconus requires corneal transplantation, for which the gold standard is deep anterior lamellar keratoplasty (DALK), preserving the healthy Descemet's membrane and endothelium. The safety and reproducibility of corneal cuts have been improved by the evolution of femtosecond lasers in refractive surgery, and femtosecond laser in DALK would seem to provide the same advantages over the manual method. In our retrospective study, we compare functional and anatomical results of femtosecond-assisted DALK versus manual trephination DALK in patients with keratoconus in stage 4 of the Krumeich classification...
June 7, 2017: Journal Français D'ophtalmologie
Sharif Hashmani, Nauman Hashmani, Hina Rajani, Priyanka Ramesh, Junaid Ahmed Soomro, Syed Rashid Hussain Shah, Jaish Kumar, Sayed Mustafa Mahmood Shah
PURPOSE: To compare refractive outcomes, visual acuities, and satisfaction of patients between those treated with laser-assisted in situ keratomileusis (LASIK) using a Hansatome microkeratome (HM) and femto-assisted laser (FAL). METHODS: This was a retrospective analysis of 1,366 eyes in 687 patients who underwent LASIK with an HM (n=1,137) and an FAL (n=229) at the two centers of Hashmanis Hospital, Karachi, Pakistan. Refractive outcomes, including sphere, cylinder, and spherical equivalent in diopters (D), and visual acuities were assessed both preoperatively and at 1 month follow-up...
2017: Clinical Ophthalmology
Lisa Lautner, Kristyna Pluhackova, Nicolai K H Barth, Tilo Seydel, Wiebke Lohstroh, Rainer A Böckmann, Tobias Unruh
Neutron scattering is a powerful tool to study relaxation processes in biological membrane mimics in space and time. Combining different inelastic and quasielastic neutron scattering techniques, a large dynamic range can be covered: from atomic to mesoscopic lengths and from femto- to some hundreds of nanoseconds in time. This allows studies on e.g. the diffusion of lipids, the membrane undulation motions, the dispersion of sound waves in membranes as well as the mutual interactions of membrane constituents such as lipids, proteins, and additives...
August 2017: Chemistry and Physics of Lipids
Avishek Saha, Alicia Moya, Axel Kahnt, Daniel Iglesias, Silvia Marchesan, Reinhold Wannemacher, Maurizio Prato, Juan J Vilatela, Dirk M Guldi
A new insight into photoinduced charge transfer processes across carbon nanotube@TiO2 interfaces has been gained based on experimental details from transient absorption spectroscopy. We show that photoinduced, interfacial hole transfer to carboxylic acid-functionalized multiwalled carbon nanotubes (oxMWCNTs) from TiO2 results in hole-doped oxMWCNTs and reduced TiO2. The latter is inferred from femto- and nanosecond transient absorption spectroscopy performed with oxMWCNT@TiO2 dispersions and complemented with investigations using methyl viologen and N,N,N',N'-tetramethyl-p-phenylenediamine as an electron scavenger and a hole scavenger, respectively...
June 1, 2017: Nanoscale
Martina Ebner, Siegfried Mariacher, Kai Januschowski, Katrin Boden, Anna-Maria Seuthe, Peter Szurman, Karl Thomas Boden
BACKGROUND: To evaluate intraocular pressure (IOP) using the application of a novel liquid patient interface for femtosecond laser-assisted cataract surgery with the FEMTO LDV Z8. METHODS: IOP was evaluated in enucleated porcine eyes prior, during and after the application of the Femto LDV Z8 liquid patient interface (Ziemer Ophthalmic Systems, Switzerland) using intracameral cannulation (n=20), intravitreal cannulation (n=20), rebound tonometry (n=20) and indentation tonometry (n=20)...
August 2017: British Journal of Ophthalmology
Gabriel F Dorlhiac, Clyde Fare, Jasper J van Thor
Ultrafast spectroscopy offers temporal resolution for probing processes in the femto- and picosecond regimes. This has allowed for investigation of energy and charge transfer in numerous photoactive compounds and complexes. However, analysis of the resultant data can be complicated, particularly in more complex biological systems, such as photosystems. Historically, the dual approach of global analysis and target modelling has been used to elucidate kinetic descriptions of the system, and the identity of transient species respectively...
May 2017: PLoS Computational Biology
Alexander S Fokas, Daniel J Cole, Nicholas D M Hine, Stephen A Wells, Michael C Payne, Alex W Chin
Observation of excitonic quantum beats in photosynthetic antennae has prompted wide debate regarding the function of excitonic coherence in pigment-protein complexes. Much of this work focuses on the interactions of excitons with the femto-to-picosecond dynamical fluctuations of their environment. However, in experiments these effects can be masked by static disorder of the excited-state energies across ensembles, whose microscopic origins are challenging to predict. Here the excited-state properties of ∼2000 atom clusters of the Fenna-Matthews-Olson complex are simulated using a unique combination of linear-scaling density functional theory and constrained geometric dynamics...
May 11, 2017: Journal of Physical Chemistry Letters
Yohei Uemura, Daiki Kido, Akihiro Koide, Yuki Wakisaka, Yasuhiro Niwa, Shunsuke Nozawa, Kohei Ichiyanagi, Ryo Fukaya, Shin-Ichi Adachi, Tetsuo Katayama, Tadashi Togashi, Shigeki Owada, Makina Yabashi, Keisuke Hatada, Akihide Iwase, Akihiko Kudo, Satoru Takakusagi, Toshihiko Yokoyama, Kiyotaka Asakura
Ultrafast excitation of photocatalytically active BiVO4 was characterized by femto- and picosecond transient X-ray absorption fine structure spectroscopy. An initial photoexcited state (≪500 fs) changed to a metastable state accompanied by a structural change with a time constant of ∼14 ps. The structural change might stabilize holes on oxygen atoms since the interaction between Bi and O increases.
June 29, 2017: Chemical Communications: Chem Comm
Damien Laage, Thomas Elsaesser, James T Hynes
The structure and function of biomolecules can be strongly influenced by their hydration shells. A key challenge is thus to determine the extent to which these shells differ from bulk water, since the structural fluctuations and molecular excitations of hydrating water molecules within these shells can cover a broad range in both space and time. Recent progress in theory, molecular dynamics simulations, and ultrafast vibrational spectroscopy has led to new and detailed insight into the fluctuations of water structure, elementary water motions, and electric fields at hydrated biointerfaces...
July 2017: Structural Dynamics (Melville, N.Y.)
Avishek Saha, Muqing Chen, Marcus Lederer, Axel Kahnt, Xing Lu, Dirk M Guldi
An unprecedented family of novel electron-donor acceptor conjugates based on fullerenes as electron acceptors, on one hand, and triphenyl amines as electron donors, on the other hand, have been synthesized and characterized in a variety of solvents using steady state absorption/emission as well as transient absorption spectroscopy. These are unprecedented in terms of their outcome of radical ion pair formation, that is, the singlet versus triplet excited state. This was corroborated by femto/nanosecond pump probe experiments and by molecular orbital calculations...
February 1, 2017: Chemical Science
Zubair Shahid Bashir, Muhammad Hassaan Ali, Ayesha Anwar, Muhammad Hammad Ayub, Nadeem Hafeez Butt
Femtosecond laser has been introduced in refractive surgery to create a thin-hinged corneal flap without using any blade. The current review was planned to analyse and compare femtosecond-assisted laser in-situ keratomileusis (LASIK), the latest refractive procedure, with conventional techniques in refractive surgery. The analysis showed that femtosecond-assisted LASIK yielded more predictable corneal flaps, lesser ocular aberrations, better uncorrected visual acuity, lesser variations in intraocular pressure (IOP) and fewer chances of developing dry eyes...
April 2017: JPMA. the Journal of the Pakistan Medical Association
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