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https://www.readbyqxmd.com/read/28330186/a-comprehensive-study-of-one-step-selenization-process-for-cu-in1-x-ga-x-se2-thin-film-solar-cells
#1
Shih-Chen Chen, Sheng-Wen Wang, Shou-Yi Kuo, Jenh-Yih Juang, Po-Tsung Lee, Chih Wei Luo, Kaung-Hsiung Wu, Hao-Chung Kuo
In this work, aiming at developing a rapid and environmental-friendly process for fabricating CuIn1-x Ga x Se2 (CIGS) solar cells, we demonstrated the one-step selenization process by using selenium vapor as the atmospheric gas instead of the commonly used H2Se gas. The photoluminescence (PL) characteristics indicate that there exists an optimal location with superior crystalline quality in the CIGS thin films obtained by one-step selenization. The energy dispersive spectroscopy (EDS) reveals that the Ga lateral distribution in the one-step selenized CIGS thin film is intimately correlated to the blue-shifted PL spectra...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28328227/ultrafast-relaxation-dynamics-of-photoexcited-heme-model-compounds-observation-of-multiple-electronic-spin-states-and-vibrational-cooling
#2
Chinju Govind, Venugopal Karunakaran
Hemin is a unique model compound of heme proteins carrying out variable biological functions. Here the excited state relaxation dynamics of heme model compounds in the ferric form are systematically investigated by changing the axial ligand (Cl/Br), the peripheral substituent (Vinyl/Ethylmeso) and the solvent (Methanol/DMSO) using femtosecond pump-probe spectroscopy upon excitation at 380 nm. The relaxation time constants of these model compounds are obtained by global analysis. Excited state deactivation pathway of the model compounds comprising the decay of the porphyrin excited state (S*) to Ligand to Metal Charge Transfer state (LMCT, t1), back electron transfer from Metal to Ligand (MLCT, t2) and relaxation to the ground state through different electronic spin states of iron (t3 and t4), is proposed along with the vibrational cooling processes...
March 22, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28327611/biomimetic-surface-structuring-using-cylindrical-vector-femtosecond-laser-beams
#3
Evangelos Skoulas, Alexandra Manousaki, Costas Fotakis, Emmanuel Stratakis
We report on a new, single-step and scalable method to fabricate highly ordered, multi-directional and complex surface structures that mimic the unique morphological features of certain species found in nature. Biomimetic surface structuring was realized by exploiting the unique and versatile angular profile and the electric field symmetry of cylindrical vector (CV) femtosecond (fs) laser beams. It is shown that, highly controllable, periodic structures exhibiting sizes at nano-, micro- and dual- micro/nano scales can be directly written on Ni upon line and large area scanning with radial and azimuthal polarization beams...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28326779/illuminating-photochemistry-of-an-excitation-ratiometric-fluorescent-protein-calcium-biosensor
#4
Longteng Tang, Yanli Wang, Weimin Liu, Yongxin Zhao, Robert E Campbell, Chong Fang
Fluorescent protein (FP) based biosensors have become an important and promising tool to track metal ion movement inside living systems. Their working principles after light irradiation, however, remain elusive. To facilitate the rational design of biosensors, we dissect the fluorescence modulation mechanism of a newly developed excitation ratiometric green FP-based Ca(2+) biosensor, GEX-GECO1, using femtosecond stimulated Raman spectroscopy (FSRS) in the electronic excited state. Upon 400 nm photoexcitation, characteristic vibrational marker bands at ~1180 and 1300 cm(-1) show concomitant decay and rise dynamics, probing the progression of an ultrafast excited state proton transfer (ESPT) reaction...
March 22, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28325048/photoinduced-single-and-multiple-electron-dynamics-processes-enhanced-by-quantum-confinement-in-lead-halide-perovskite-quantum-dots
#5
Dayton Jon Vogel, Andrei Kryjevski, Talgat M Inerbaev, Dmitri S Kilin
Methyl-ammonium lead iodide perovskite (MAPbI3) is a promising material for photovoltaic devices. A modification of the MAPbI3 into confined nanostructures is expected to further increase efficiency of solar energy conversion. Photo-excited dynamic processes in a MAPbI3 quantum dot (QD) have been modeled by many-body perturbation theory and nonadiabatic dynamics. A photoexcitation is followed by either exciton cooling (EC), its radiative (RR) or non-radiative recombination (NRR), or multi-exciton generation (MEG) processes...
March 21, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28321446/dissecting-charge-relaxation-pathways-in-cdse-cds-nanocrystals-using-femtosecond-two-dimensional-electronic-spectroscopy
#6
J W Jarrett, C Yi, T Stoll, J Rehault, A Oriana, F Branchi, G Cerullo, K L Knappenberger
Exciton relaxation dynamics of CdSe and quasi-type-II CdSe/CdS core/shell nanocrystals were examined using femtosecond two-dimensional electronic spectroscopy (2DES). The use of 2DES allowed for determination of structure-specific and state-resolved carrier dynamics for CdSe nanocrystals formed with five, or fewer, CdS passivation monolayers (ML). For CdSe and CdSe/CdS nanocrystals formed with one through three MLs of CdS, excitation using broad bandwidth femtosecond visible laser pulses generated electron-hole pairs among the |X1〉 = 2...
March 21, 2017: Nanoscale
https://www.readbyqxmd.com/read/28320908/reaction-and-relaxation-at-surface-hotspots-using-molecular-dynamics-and-the-energy-grained-master-equation-to-describe-diamond-etching
#7
David R Glowacki, W J Rodgers, Robin Shannon, Struan H Robertson, Jeremy N Harvey
The extent to which vibrational energy transfer dynamics can impact reaction outcomes beyond the gas phase remains an active research question. Molecular dynamics (MD) simulations are the method of choice for investigating such questions; however, they can be extremely expensive, and therefore it is worth developing cheaper models that are capable of furnishing reasonable results. This paper has two primary aims. First, we investigate the competition between energy relaxation and reaction at 'hotspots' that form on the surface of diamond during the chemical vapour deposition process...
April 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28319388/visualizing-intramolecular-vibrational-redistribution-in-cyclotrimethylene-trinitramine-rdx-crystal-by-multiplex-coherent-anti-stokes-raman-scattering
#8
Guoyang Yu, Yangyang Zeng, Wencan Guo, Honglin Wu, Gangbei Zhu, Zhaoyang Zheng, Xianxu Zheng, Yunfei Song, Yanqiang Yang
The femtosecond time-resolved multiplex coherent anti-Stokes Raman scattering (CARS) technique has been performed to investigate the intramolecular vibrational redistribution (IVR) through vibrational couplings in RDX molecules. In the multiplex CARS experiment, the supercontinuum (SC) was used as broadband Stokes light to coherently and collectively excite multiple vibrational modes, and quantum beats arising from vibrational couplings among these modes were observed. The IVR of RDX is visualized by a topological graph of these vibrational couplings...
March 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28319382/time-resolved-spectroscopic-investigation-of-charge-trapping-in-carbon-nitrides-photocatalysts-for-hydrogen-generation
#9
Robert Godin, Yiou Wang, Martijn A Zwijnenburg, Junwang Tang, James R Durrant
Carbon nitride (g-C3N4) as a benchmark polymer photocatalyst is attracting significant research interest because of its visible light photocatalytic performance combined with good stability and facile synthesis. However, little is known about the fundamental photophysical processes of g-C3N4, which are key to explain and promote photoactivity. Using time-resolved absorption and photoluminescence spectroscopies, we have investigated the photophysics of a series of carbon nitrides on timescales ranging from femtoseconds to seconds...
March 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28317683/new-technique-for-femtosecond-laser-creation-of-clear-corneal-incisions-for-cataract-surgery
#10
Sebastiano Serrao, Daniela Giannini, Domenico Schiano-Lomoriello, Giuseppe Lombardo, Marco Lombardo
PURPOSE: To evaluate the changes in corneal topography and corneal higher-order wavefront aberrations with the use of a new technique in which clear corneal incisions (CCIs) for cataract surgery are created with a femtosecond laser. SETTING: IRCCS Fondazione G.B. Bietti, Rome, Italy. DESIGN: Prospective randomized case series. METHODS: Cataract surgery patients were randomized into 2 groups. In the study group, a 3-plane CCI was created with a femtosecond laser...
January 2017: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/28317672/differences-in-energy-expenditure-for-conventional-and-femtosecond-assisted-cataract-surgery-using-2-different-phacoemulsification-systems
#11
Nilufer Yesilirmak, Vasilios F Diakonis, Adam Sise, Daniel P Waren, Sonia H Yoo, Kendall E Donaldson
PURPOSE: To compare the mean cumulative dissipated energy (CDE) in patients having femtosecond laser-assisted or conventional phacoemulsification cataract surgery using 2 different phacoemulsification platforms. SETTING: Bascom Palmer Eye Institute, Miami, Florida, USA. DESIGN: Prospective comparative nonrandomized clinical study. METHODS: Consecutive patients were scheduled to have femtosecond laser-assisted cataract surgery with the Lensx laser or conventional phacoemulsification using an active-fluidics torsional platform (Centurion) or torsional platform (Infiniti)...
January 2017: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/28317434/dynamics-of-the-active-site-loops-in-catalyzing-aminoacylation-reaction-in-seryl-and-histidyl-trna-synthetases
#12
Saheb Dutta, Soumya Kundu, Amrita Saha, Nilashis Nandi
Aminoacylation reaction is the first step of protein biosynthesis. The catalytic reorganization at the active site of aminoacyl tRNA synthetases (aaRSs) is driven by the loop motions. There remain lacunae of understanding concerning the catalytic loop dynamics in aaRSs. We analyzed the functional loop dynamics in seryl tRNA synthetase from Methanopyrus kandleri ((mk)SerRS) and histidyl tRNA synthetases from Thermus thermophilus ((tt)HisRS), respectively, using molecular dynamics. Results confirm that the motif 2 loop and other active site loops are flexible spots within the catalytic domain...
March 20, 2017: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/28316243/underwater-transparent-miniature-mechanical-hand-based-on-femtosecond-laser-induced-controllable-oil-adhesive-patterned-glass-for-oil-droplet-manipulation
#13
Jinglan Huo, Qing Yang, Feng Chen, Jiale Yong, Yao Fang, Jingzhou Zhang, Lin Liu, Xun Hou
The development of underwater superoleophobic surfaces makes researchers be swept up in boundless imagination of their applications, thereinto the oil manipulation based on such surface attracts much attention. Here, we show a simple and effective way to fabricate an underwater transparent miniature "mechanical hand" based on controllable oil-adhesive patterned glass prepared by femtosecond laser. The underwater oil-adhesive force of the patterned glasses that compose the "mechanical hand" device can be controlled from ultralow to ultrahigh through adjusting the different fraction of the untreated flat glass area to the laser-ablated rough area...
March 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28302635/financial-modelling-of-femtosecond-laser-assisted-cataract-surgery-within-the-national-health-service-using-a-hub-and-spoke-model-for-the-delivery-of-high-volume-cataract-surgery
#14
H W Roberts, M Z Ni, D P S O'Brart
AIMS: To develop financial models which offset additional costs associated with femtosecond laser (FL)-assisted cataract surgery (FLACS) against improvements in productivity and to determine important factors relating to its implementation into the National Health Service (NHS). METHODS: FL platforms are expensive, in initial purchase and running costs. The additional costs associated with FL technology might be offset by an increase in surgical efficiency. Using a 'hub and spoke' model to provide high-volume cataract surgery, we designed a financial model, comparing FLACS against conventional phacoemulsification surgery (CPS)...
March 16, 2017: BMJ Open
https://www.readbyqxmd.com/read/28300735/comparison-of-femtosecond-laser-assisted-descemetic-and-predescemetic-lamellar-keratoplasty-for-keratoconus
#15
Yan Lu, Ana Beatriz Diniz Grisolia, Yi-Rui Ge, Chun-Yan Xue, Qian Cao, Li-Ping Yang, Zhen-Ping Huang
PURPOSE: The purpose of this study is to compare the outcomes following femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK) with 75% of stromal dissection (predescemetic group) and femtosecond laser-assisted DALK using big-bubble technique with total stromal resection (descemetic group) for the treatment of keratoconus. SUBJECTS AND METHODS: Twenty eyes of 17 patients with keratoconus were studied. There were 10 eyes of 9 patients in predescemetic group and 10 eyes of 8 patients in descemetic group...
January 2017: Indian Journal of Ophthalmology
https://www.readbyqxmd.com/read/28300413/photoinduced-chromophore-hydration-in-the-fluorescent-protein-dreiklang-is-triggered-by-ultrafast-excited-state-proton-transfer-coupled-to-a-low-frequency-vibration
#16
Fabien Lacombat, Pascal Plaza, Marie-Aude Plamont, Agathe Espagne
Because of growing applications in advanced fluorescence imaging, the mechanisms and dynamics of photoinduced reactions in reversibly photoswitchable fluorescent proteins are currently attracting much interest. We report the first time-resolved study of the photoswitching of Dreiklang, so far the only fluorescent protein to undergo reversible photoinduced chromophore hydration. Using broadband femtosecond transient absorption spectroscopy, we show that the reaction is triggered by an ultrafast deprotonation of the chromophore phenol group in the excited state in 100 fs...
March 20, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28300169/double-flow-focused-liquid-injector-for-efficient-serial-femtosecond-crystallography
#17
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
Serial femtosecond crystallography requires reliable and efficient delivery of fresh crystals across the beam of an X-ray free-electron laser over the course of an experiment. We introduce a double-flow focusing nozzle to meet this challenge, with significantly reduced sample consumption, while improving jet stability over previous generations of nozzles. We demonstrate its use to determine the first room-temperature structure of RNA polymerase II at high resolution, revealing new structural details. Moreover, the double flow-focusing nozzles were successfully tested with three other protein samples and the first room temperature structure of an extradiol ring-cleaving dioxygenase was solved by utilizing the improved operation and characteristics of these devices...
March 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28299715/assessment-of-reproducibility-of-laser-electrospray-mass-spectrometry-using-electrospray-deposition-of-analyte
#18
Habiballah Sistani, Santosh Karki, Jieutonne J Archer, Fengjian Shi, Robert J Levis
A nonresonant, femtosecond (fs) laser is employed to desorb samples of Victoria blue deposited on stainless steel or indium tin oxide (ITO) slides using either electrospray deposition (ESD) or dried droplet deposition. The use of ESD resulted in uniform films of Victoria blue whereas the dried droplet method resulted in the formation of a ring pattern of the dye. Laser electrospray mass spectrometry (LEMS) measurements of the ESD-prepared films on either substrate were similar and revealed lower average relative standard deviations for measurements within-film (20...
March 15, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28299005/preliminary-results-of-femtosecond-laser-assisted-cataract-surgery-in-a-private-clinic-in-iran
#19
Farhad Nejat, Sara Sarahati, Sahar Mojaled Nobari, Khosrow Jadidi, Mostafa Naderi, Mohammad Amin Nejat
PURPOSE: To report the preliminary results of femtosecond laser-assisted cataract surgery in Iranian patients. METHODS: This prospective case series included 21 eyes of 21 patients with cataract. Mean patient age was 66.7 ± 10 years. The patients underwent femtosecond-laser assisted cataract surgery (VICTUS Femtosecond Laser Platform: Bausch + Lomb) and intraocular lens (IOL) implementation in Bina Eye Hospital, Tehran, Iran between May and October, 2014. Visual outcomes, intraocular pressure (IOP), and complications were evaluated three months after surgery...
January 2017: Journal of Ophthalmic & Vision Research
https://www.readbyqxmd.com/read/28295982/light-harvesting-and-photocurrent-generation-in-a-conjugated-polymer-nanoparticle-reduced-graphene-oxide-composite
#20
Amitava Patra, Arnab Ghosh, Bikash Jana, Sourav Maiti, Rajesh Bera, Hiren Ghosh
Polymer - graphene nanocomposites are promising candidates towards light harvesting systems such as photocatalysis, photovoltaics; where significant charge separation occurs due to photoinduced electron transfer. Much attention has been paid to use reduced graphene oxide (r-GO) as template for anchoring various nanomaterials due to its efficient electron accepting and transport property. Here, we have prepared Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) nanoparticles from MEH-PPV polymer and investigate the change in photophysical properties due to formation of polymer nanoparticles from molecular state by using steady state and time resolved spectroscopy...
March 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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