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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.
May 8, 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
A Balestrazzi, A Balestrazzi, F Menicacci, G Cartocci, F Menicacci, P Michieletto, E Balestrazzi
PurposeTo evaluate the refractive and visual results of one-stage laser-assisted in situ keratomileusis with femtosecond laser (Femto-LASIK) for the correction of residual ametropia after deep anterior lamellar keratoplasty (DALK).MethodsThis retrospective study included 13 eyes of 12 patients, who underwent corneal Femto-LASIK to correct refractive errors after DALK. IntraLase FS150 was used to create a lamellar flap and excimer laser ablation for refractive correction was performed using the Star S4 IR Excimer Laser in eight cases and the Technolas 217z Excimer Laser in Tissue Saving mode in five cases...
April 7, 2017: Eye
Hirendra Nath Ghosh, Tushar Debnath, Deepa Sebastian, Sourav Maiti
Charge transfer processes from photo-excited CdSe QDs to phenol derivatives with electron donating (4-methoxy) and electron withdrawing (4-nitro) moiety have been demonstrated by using steady state and time-resolved emission and femto-second transient absorption spectroscopy. Steady state and time-resolved emission studies suggest that in presence of both 4-nitro phenol (4NP) and 4-methoxy phenol (4MP) CdSe QDs luminescence gets quenched. Stern-Volmer analysis suggests both static and dynamic mechanisms are active for both the QD/phenol composites...
March 27, 2017: Chemistry: a European Journal
Xian-Sheng Ke, Taeyeon Kim, James T Brewster, Vincent M Lynch, Dongho Kim, Jonathan L Sessler
An expanded rosarian (P3P6) with a bowl-like conformation has been prepared and characterized in a one-pot procedure that involves condensing a bispyrrole pyridine precursor (P1P2) with benzaldehyde, followed by oxidation. Single crystal X-ray diffraction analysis reveals a bowl-like conformation in the solid state with an upper rim diameter defined by the meso-phenyl substituents of ca. 13.5 Å and a depth of roughly 6.3 Å. P3P6 forms both 1:1 and 2:1 complexes with C60 in the solid state. DFT reveals similar energies for the two binding modes...
March 24, 2017: Journal of the American Chemical Society
Mingxia Tian, Ping Ma, Guoying Mu
PURPOSE: To compare the visual acuity and contrast sensitivity (CS) after femto laser in situ keratomileusis (fLASIK) and orthokeratology (OK) in patients with low-to-moderate myopia. METHODS: A total of 68 patients were enrolled in this prospective cohort study. Of these, 40 eyes from 40 patients with low-to-moderate myopia underwent fLASIK and 28 eyes from 28 patients underwent OK. In addition to uncorrected distance visual acuity and corrected distance visual acuity, photopic and mesopic CS (with CSV-1000E) were tested before treatment and at 1, 3, and 6 months after treatment...
February 27, 2017: Eye & Contact Lens
Wataru Suzuki, Hiroaki Kotani, Tomoya Ishizuka, Kei Ohkubo, Yoshihito Shiota, Kazunari Yoshizawa, Shunichi Fukuzumi, Takahiko Kojima
Addition of 1 equiv of TFA to an acetone solution containing dodecaphenylporphyrin (H2 DPP) in the presence of 10 % MeOH (v/v) resulted in selective formation of a monoprotonated form (H3 DPP(+) ), in sharp contrast to protonation of H2 DPP directly affording a diprotonated form (H4 DPP(2+) ) in acetone in the absence of MeOH. The crucial role of MeOH for selective H3 DPP(+) formation was interpreted as hydrogen-bonding stabilization of H3 DPP(+) , since a MeOH molecule was found to form hydrogen bonds with an NH proton of H3 DPP(+) in the crystal...
February 7, 2017: Chemistry: a European Journal
B Meyer, K S Kunert
With a rate of less than 2 %, retreatment after SMILE is rare. If a touch-up is required, there are different options to choose from: surface ablation (PRK/LASEK) with Mitomycin C, the standard femto-flap procedure with the same parameters, the CIRCLE procedure, which extends the previous SMILE interface into a flap, or the innovative but off-label capless SMILE procedure, which preserves all the advantages of SMILE.
January 2017: Klinische Monatsblätter Für Augenheilkunde
M F Ciappina, J A Pérez-Hernández, A S Landsman, W A Okell, S Zherebtsov, B Förg, J Schötz, L Seiffert, T Fennel, T Shaaran, T Zimmermann, A Chacón, R Guichard, A Zaïr, J W G Tisch, J P Marangos, T Witting, A Braun, S A Maier, L Roso, M Krüger, P Hommelhoff, M F Kling, F Krausz, M Lewenstein
Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond  =  1 as  =  10(-18) s), which is comparable with the optical field. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is  ∼152 as...
May 2017: Reports on Progress in Physics
Evgeni M Glebov, Ivan P Pozdnyakov, Svetlana G Matveeva, Alexei A Melnikov, Sergey V Chekalin, Marina V Rogozina, Vladislav V Yudanov, Vjacheslav P Grivin, Victor F Plyusnin
The photoaquation of the Os(IV)Cl6(2-) complex was studied by means of stationary photolysis, nanosecond laser flash photolysis and ultrafast kinetic spectroscopy. The Os(IV)Cl5(OH)(2-) complex was found to be the only reaction product. The quantum yield of photoaquation is rather low and wavelength-dependent. No impact of redox processes on photoaquation was revealed. The total characteristic lifetime of the process is about 80 ps. Three intermediates were recorded in the femto- and picosecond time domains and assigned to different Os(iv) species...
December 22, 2016: Photochemical & Photobiological Sciences
Xiaogang Lin, Cheng Cheng, Paul Terry, Jiangang Chen, Haochen Cui, Jayne Wu
Bisphenol A (BPA) is an endocrine disrupting compound that may have adverse developmental, reproductive, neurological, and immune system effects. Low-level exposure to BPA is ubiquitous in human populations due to its widespread use in consumer products. Therefore, highly sensitive methods are needed to quantify BPA in various matrices including water, serum, and food products. In this study, we developed a simple, rapid, highly sensitive and specific sensor based on an aptamer probe and AC electrokinetics capacitive sensing method that successfully detected BPA at femto molar (fM) levels, which is an improvement over prior work by a factor of 10...
May 15, 2017: Biosensors & Bioelectronics
Ying Jin, Yan Wang, Lulu Xu, Tong Zuo, Hua Li, Rui Dou, Jiamei Zhang
Purpose. To investigate the visual quality after SMILE and Femto-LASIK. Methods. About 123 eyes from 63 patients were enrolled in this study. The parameters were measured preoperatively and 1 week, 1 month, and 3 months postoperatively using Sirius System. Results. The MTF curve increase slightly from low to high frequency at 3 mm and 6 mm pupil diameter after SMILE surgery (P < 0.05) during the follow-up time comparing with the preoperative values. And the SR has a significant increase at various pupil diameters as well (P < 0...
2016: Journal of Ophthalmology
Leonardo Mastropasqua, Roberta Calienno, Claudia Curcio, Rodolfo Mastropasqua, Mario Nubile, Niccolò Salgari, Manuela Lanzini
PURPOSE: To detect corneal inflammation and apoptosis induced after small incision lenticule extraction (SMILE) at different refractive corrections for moderate to high values of myopia. METHODS: Fifty patients (50 eyes) suffering from medium to high myopia (spherical equivalent refraction from -3.75 to -10.00 diopters (D) with refractive astigmatism under -0.75 D) underwent SMILE in order to correct myopic error. In vivo evaluation was done by corneal confocal microscopy (IVCM) and ex vivo by immunohistochemistry...
December 2, 2016: Current Eye Research
Abraham Vázquez-Guardado, Alexandra Smith, Wade Wilson, Jeanette Ortega, J Manuel Perez, Debashis Chanda
Simple optical techniques that can accurately and selectively identify organic and inorganic material in a reproducible manner are of paramount importance in biological sensing applications. In this work, we demonstrate that a nanoimprinted plasmonic pattern with locked-in dimensions supports sharp deterministic hybrid resonances when coupled with an optical cavity suitable for high sensitive surface detection. The surface sensing property of this hybrid system is quantified by precise atomic layer growth of aluminum oxide using the atomic layer deposition technique...
October 31, 2016: Optics Express
Zhu Xiao, Hongjing Liu, Vincent Havyarimana, Tong Li, Dong Wang
In this paper, we investigate the coverage performance and energy efficiency of multi-tier heterogeneous cellular networks (HetNets) which are composed of macrocells and different types of small cells, i.e., picocells and femtocells. By virtue of stochastic geometry tools, we model the multi-tier HetNets based on a Poisson point process (PPP) and analyze the Signal to Interference Ratio (SIR) via studying the cumulative interference from pico-tier and femto-tier. We then derive the analytical expressions of coverage probabilities in order to evaluate coverage performance in different tiers and investigate how it varies with the small cells' deployment density...
November 4, 2016: Sensors
Ashvin Agarwal, Soosan Jacob
PURPOSE OF REVIEW: The purpose is to review the current and effective advantages of femtosecond laser-assisted cataract surgery (FLACS). RECENT FINDINGS: FLACS has advantages over manual phacoemulsification in its precision, and predictability and may be especially advantageous in difficult situations such as shallow anterior chamber, subluxated cataracts, white cataracts, and so on. However, the femtosecond capsulorhexis may not be as strong as a manual rhexis...
January 2017: Current Opinion in Ophthalmology
Martin Heberle, Stefanie Tschierlei, Nils Rockstroh, Mark Ringenberg, Wolfgang Frey, Henrik Junge, Matthias Beller, Stefan Lochbrunner, Michael Karnahl
A series of heteroleptic copper(I) photosensitizers of the type [(P^P)Cu(N^N)](+) with an extended π-system in the backbone of the diimine ligand has been prepared. The structures of all complexes are completely characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. These novel photosensitizers were assessed with respect to the photocatalytic reduction of protons in the presence of triethylamine and [Fe3 (CO)12 ]. Although the solid-state structures and computational results show no significant impact of the π-extension on the structural properties, decreased activities were observed...
October 21, 2016: Chemistry: a European Journal
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