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https://www.readbyqxmd.com/read/28944255/soft-x-ray-absorption-spectroscopy-of-metalloproteins-and-high-valent-metal-complexes-at-room-temperature-using-free-electron-lasers
#1
Markus Kubin, Jan Kern, Sheraz Gul, Thomas Kroll, Ruchira Chatterjee, Heike Löchel, Franklin D Fuller, Raymond G Sierra, Wilson Quevedo, Christian Weniger, Jens Rehanek, Anatoly Firsov, Hartawan Laksmono, Clemens Weninger, Roberto Alonso-Mori, Dennis L Nordlund, Benedikt Lassalle-Kaiser, James M Glownia, Jacek Krzywinski, Stefan Moeller, Joshua J Turner, Michael P Minitti, Georgi L Dakovski, Sergey Koroidov, Anurag Kawde, Jacob S Kanady, Emily Y Tsui, Sandy Suseno, Zhiji Han, Ethan Hill, Taketo Taguchi, Andrew S Borovik, Theodor Agapie, Johannes Messinger, Alexei Erko, Alexander Föhlisch, Uwe Bergmann, Rolf Mitzner, Vittal K Yachandra, Junko Yano, Philippe Wernet
X-ray absorption spectroscopy at the L-edge of 3d transition metals provides unique information on the local metal charge and spin states by directly probing 3d-derived molecular orbitals through 2p-3d transitions. However, this soft x-ray technique has been rarely used at synchrotron facilities for mechanistic studies of metalloenzymes due to the difficulties of x-ray-induced sample damage and strong background signals from light elements that can dominate the low metal signal. Here, we combine femtosecond soft x-ray pulses from a free-electron laser with a novel x-ray fluorescence-yield spectrometer to overcome these difficulties...
September 2017: Structural Dynamics (Melville, N.Y.)
https://www.readbyqxmd.com/read/28944205/clinical-outcomes-of-small-incision-lenticule-extraction-versus-femtosecond-laser-assisted-lasik-for-myopia-a-meta-analysis
#2
Huan Yan, Li-Yan Gong, Wei Huang, Yan-Li Peng
AIM: To evaluate the possible differences in visual quality between small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) for myopia. METHODS: A Meta-analysis was performed. Patients were from previously reported comparative studies treated with SMILE versus FS-LASIK. The PubMed, EMBASE, Cochrane, Web of Science and Chinese databases (i.e. WANFANG and CNKI) were searched in Nov. of 2016 using RevMan 5.1 version software...
2017: International Journal of Ophthalmology
https://www.readbyqxmd.com/read/28941458/femtosecond-relaxation-processes-in-rhodobacter-sphaeroides-reaction-centers
#3
A G Yakovlev, V A Shuvalov
Energy relaxation was studied with difference femtosecond spectroscopy in reaction centers of the YM210L mutant of the purple photosynthetic bacterium Rhodobacter sphaeroides at low temperature (90 K). A dynamical long-wavelength shift of stimulated emission of the excited state of the bacteriochlorophyll dimer P was found, which starts simultaneously with P* formation and is accompanied by a change in the spectral shape of this emission. The characteristic value of this shift was about 30 nm, and the characteristic time about 200 fs...
August 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28940940/tuning-excitonic-properties-of-monolayer-mos2-with-microsphere-cavity-by-high-throughput-chemical-vapor-deposition-method
#4
Yang Mi, Zhepeng Zhang, Liyun Zhao, Shuai Zhang, Jie Chen, Qingqing Ji, Jianping Shi, Xiebo Zhou, Rui Wang, Jia Shi, Wenna Du, Zhiyong Wu, Xiaohui Qiu, Qing Zhang, Yanfeng Zhang, Xinfeng Liu
Tuning the optical properties of 2D direct bandgap semiconductors is crucial for applications in photonic light source, optical communication, and sensing. In this work, the excitonic properties of molybdenum disulphide (MoS2 ) are successfully tuned by directly depositing it onto silica microsphere resonators using chemical vapor deposition method. Multiple whispering gallery mode (WGM) peaks in the emission wavelength range of ≈650-750 nm are observed under continuous wave excitation at room temperature...
September 20, 2017: Small
https://www.readbyqxmd.com/read/28936519/a-simple-way-to-achieve-bioinspired-hybrid-wettability-surface-with-micro-nanopatterns-for-efficient-fog-collection
#5
Kai Yin, Haifeng Du, Xinran Dong, Cong Wang, Ji-An Duan, Jun He
Fog collection is receiving increasing attention for providing water in semi-arid deserts and inland areas. Inspired by the fog harvesting ability of the hydrophobic-hydrophilic surface of Namib desert beetles, we present a simple, low-cost method to prepare a hybrid superhydrophobic-hydrophilic surface. The surface contains micro/nanopatterns, and is prepared by incorporating femtosecond-laser fabricated polytetrafluoroethylene nanoparticles deposited on superhydrophobic copper mesh with a pristine hydrophilic copper sheet...
September 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28935962/excitation-of-coupled-spin-orbit-dynamics-in-cobalt-oxide-by-femtosecond-laser-pulses
#6
Takuya Satoh, Ryugo Iida, Takuya Higuchi, Yasuhiro Fujii, Akitoshi Koreeda, Hiroaki Ueda, Tsutomu Shimura, Kazuo Kuroda, V I Butrim, B A Ivanov
Ultrafast control of magnets using femtosecond light pulses attracts interest regarding applications and fundamental physics of magnetism. Antiferromagnets are promising materials with magnon frequencies extending into the terahertz range. Visible or near-infrared light interacts mainly with the electronic orbital angular momentum. In many magnets, however, in particular with iron-group ions, the orbital momentum is almost quenched by the crystal field. Thus, the interaction of magnons with light is hampered, because it is only mediated by weak unquenching of the orbital momentum by spin-orbit interactions...
September 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28935513/non-invasive-tryptophan-fluorescence-measurements-as-a-novel-method-of-grading-cataract
#7
Jesper Høiberg Erichsen, Aurore Mensah, Line Kessel
Development of non-invasive treatments for cataract calls for a sensitive diagnostic assay. We conducted a study to test whether the ratio of folded tryptophan to non-tryptophan fluorescence emission (F-factor) may be used for grading cataracts in human lenses. The F-factor was measured on aspirated lens material from eyes undergoing femtosecond laser assisted cataract surgery (FLACS) and was compared to a preoperative optical grading of cataract using Scheimpflug imaging. The preoperative optical grading allocated the cataracts to 1 of 4 categories according to the density of the cataract...
September 18, 2017: Experimental Eye Research
https://www.readbyqxmd.com/read/28933858/energy-gap-law-for-exciton-dynamics-in-gold-cluster-molecules
#8
Kyuju Kwak, Viraj Dhanushka Thanthirige, Kyunglim Pyo, Dongil Lee, Guda Ramakrishna
The energy gap law relates the nonradiative decay rate to the energy gap separating the ground and excited states. Here we report that the energy gap law can be applied to exciton dynamics in gold cluster molecules. Size-dependent electrochemical and optical properties were investigated for a series of hexanethiolate-protected gold clusters ranging from Au25 to Au333. Voltammetric studies reveal that the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps of these clusters decrease with increasing cluster size...
September 21, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28933458/suppression-of-fragmentation-in-multiphoton-ionization-mass-spectrometry-using-a-near-infrared-femtosecond-laser-as-an-ionization-source
#9
Adan Li, Thang Phan Dinh, Tomoko Imasaka, Totaro Imasaka
The ionization and fragmentation processes for pentachlorobenzene were examined using a femtosecond laser emitting at 400, 800, and 1200 nm. A molecular ion was clearly observed in the mass spectrum, since the molecule can be directly ionized from the singlet electronic exited state before relaxation to triplet levels, because the pulse width of the laser is shorter than the lifetime of the excited state. Fragmentation was minimal at 1200 nm, in contrast to ionization at 800 and 400 nm. Indeed, a doubly-charged molecular ion was prominent at 800 nm, owing to the absorption band of the singly-charged molecular ion at this wavelength...
September 21, 2017: Analyst
https://www.readbyqxmd.com/read/28932339/penetrating-keratoplasty-for-keratoconus-excimer-versus-femtosecond-laser-trephination
#10
Berthold Seitz, Achim Langenbucher, Tobias Hager, Edgar Janunts, Moatasem El-Husseiny, Nora Szentmáry
BACKGROUND: In case of keratoconus, rigid gas-permeable contact lenses as the correction method of first choice allow for a good visual acuity for quite some time. In a severe stage of the disease with major cone-shaped protrusion of the cornea, even specially designed keratoconus contact lenses are no more tolerated. In case of existing contraindications for intrastromal ring segments, corneal transplantation typically has a very good prognosis. METHODS: In case of advanced keratoconus - especially after corneal hydrops due to rupture of Descemet's membrane - penetrating keratoplasty (PKP) still is the surgical method of first choice...
2017: Open Ophthalmology Journal
https://www.readbyqxmd.com/read/28931903/plasmonic-enhancement-of-selective-photonic-virus-inactivation
#11
Mina Nazari, Min Xi, Sarah Lerch, M H Alizadeh, Chelsea Ettinger, Hisashi Akiyama, Christopher Gillespie, Suryaram Gummuluru, Shyamsunder Erramilli, Björn M Reinhard
Femtosecond (fs) pulsed laser irradiation techniques have attracted interest as a photonic approach for the selective inactivation of virus contaminations in biological samples. Conventional pulsed laser approaches require, however, relatively long irradiation times to achieve a significant inactivation of virus. In this study, we investigate the enhancement of the photonic inactivation of Murine Leukemia Virus (MLV) via 805 nm femtosecond pulses through gold nanorods whose localized surface plasmon resonance overlaps with the excitation laser...
September 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28931181/-refractive-lens-exchange
#12
Fritz H Hengerer, Ina Conrad-Hengerer
In refractive surgery the removal of the natural lens followed by implantation of an artificial intraocular lens has been an established method to treat refractive errors. The term "clear lens exchange" separates this approach from cataract surgery, where a cloudy lens has to be removed. With regard to currently available intraocular lens technologies, there is a wide range to correct myopia, hyperopia as well as astigmatism. Trifocal or extended depth-of-focus lenses (EDOF) even with a toric component offer the patients a potential benefit to further address presbyopia, respectively...
September 20, 2017: Klinische Monatsblätter Für Augenheilkunde
https://www.readbyqxmd.com/read/28930344/electron-dynamics-in-mos2-graphite-heterostructures
#13
Xinwu Zhang, Dawei He, Lixin Yi, Siqi Zhao, Jiaqi He, Yongsheng Wang, Hui Zhao
The electron dynamics in heterostructures formed by multilayer graphite and monolayer or bulk MoS2 were studied by femtosecond transient absorption measurements. Samples of monolayer MoS2-multilayer graphite and bulk MoS2-multilayer graphite were fabricated by exfoliation and dry transfer techniques. Ultrafast laser pulses were used to inject electron-hole pairs into monolayer or bulk MoS2. The transfer of these photocarriers to the adjacent multilayer graphite was time resolved by measuring the differential reflection of a probe pulse...
September 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28928982/corneal-spherical-aberration-and-corneal-asphericity-after-small-incision-lenticule-extraction-and-femtosecond-laser-assisted-lasik
#14
Hui Zhang, Yan Wang, Hua Li
PURPOSE: To investigate corneal spherical aberration and corneal asphericity after small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). METHODS: This study enrolled 70 patients having SMILE and 64 subjects receiving FS-LASIK. The preoperative spherical equivalent (SE) was -5.83 ± 1.23 diopters (D) and -6.20 ± 1.52 D, respectively. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), SE, corneal spherical aberration, and asphericity over the 6...
2017: Journal of Ophthalmology
https://www.readbyqxmd.com/read/28928484/highly-sensitive-fiber-optic-accelerometer-by-grating-inscription-in-specific-core-dip-fiber
#15
Qiangzhou Rong, Tuan Guo, Weijia Bao, Zhihua Shao, Gang-Ding Peng, Xueguang Qiao
A highly sensitive fiber-optic accelerometer based on detecting the power output of resonances from the core dip is demonstrated. The sensing probe comprises a compact structure, hereby a short section of specific core (with a significant core dip) fiber stub containing a straight fiber Bragg grating is spliced to another single-mode fiber via a core self-alignment process. The femtosecond laser side-illumination technique was utilized to ensure that the grating inscription region is precisely positioned and compact in size...
September 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28926275/mapping-photoemission-and-hot-electron-emission-from-plasmonic-nanoantennas
#16
Richard Hobbs, William Putnam, Arya Fallahi, Yujia Yang, Franz Kaertner, Karl K Berggren
Understanding plasmon-mediated electron emission and energy transfer on the nanometer length scale is critical to controlling light-matter interactions at nanoscale dimensions. In a high-resolution lithographic material, electron emission and energy transfer lead to chemical transformations. In this work, we employ such chemical transformations in two different high-resolution electron-beam lithography resists, poly(methyl methacrylate) (PMMA) and hydrogen silsesquioxane (HSQ), to map local electron emission and energy transfer with nanometer resolution from plasmonic nanoantennas excited by femtosecond laser pulses...
September 19, 2017: Nano Letters
https://www.readbyqxmd.com/read/28925255/multiphoton-activation-of-photo-spaac-click-reagents-enables-in-situ-labeling-with-submicron-resolution
#17
Christopher D McNitt, Hazel Cheng, Susanne Ullrich, Vladimir V Popik, Matthew Bjerknes
Irradiation of cyclopropenone-masked dibenzocyclooctynes with NIR pulses from a femtosecond laser triggers photodecarbonylation via non-resonant two- or three-photon excitation. Multiphoton-generated cyclooctynes undergo a SPAAC reaction with organic azides, yielding the expected triazoles. Multiphoton-triggered SPAAC (MP-SPAAC) enables high resolution 3-D photo-click derivatization of hydrogels and tissues.
September 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28924488/trion-valley-coherence-in-monolayer-semiconductors
#18
Kai Hao, Lixiang Xu, Fengcheng Wu, Philipp Nagler, Kha Tran, Xin Ma, Christian Schüller, Tobias Korn, Allan H MacDonald, Galan Moody, Xiaoqin Li
The emerging field of valleytronics aims to exploit the valley pseudospin of electrons residing near Bloch band extrema as an information carrier. Recent experiments demonstrating optical generation and manipulation of exciton valley coherence (the superposition of electron-hole pairs at opposite valleys) in monolayer transition metal dichalcogenides (TMDs) provide a critical step towards control of this quantum degree of freedom. The charged exciton (trion) in TMDs is an intriguing alternative to the neutral exciton for control of valley pseudospin because of its long spontaneous recombination lifetime, its robust valley polarization, and its coupling to residual electronic spin...
June 2017: 2d Materials
https://www.readbyqxmd.com/read/28924422/femtosecond-laser-assisted-cataract-surgery-in-vitrectomized-eye-with-posterior-chamber-phakic-intraocular-lens
#19
Natalia Anisimova, Boris Malyugin, Lisa B Arbisser, Nikolay Sobolev
We describe a case of femtosecond laser-assisted cataract surgery (FLACS) in an eye with multiple comorbidities, including retinal detachment surgery, high myopia, posterior chamber phakic intraocular lens (PC pIOL) and residual, emulsified, silicone oil located in the anterior chamber. FLACS was affected by the optical blockage, but the incomplete capsular tear was recoverable. The case suggests that silicone oil bubbles concentrated at the dome of the posterior corneal surface, along with the PC pIOL optic edges and scars after corneal astigmatic relaxing incisions can lead to incomplete anterior capsulotomy...
2017: Digital Journal of Ophthalmology: DJO
https://www.readbyqxmd.com/read/28924141/corona-discharge-induced-snow-formation-in-a-cloud-chamber
#20
Jingjing Ju, Tie-Jun Wang, Ruxin Li, Shengzhe Du, Haiyi Sun, Yonghong Liu, Ye Tian, Yafeng Bai, Yaoxiang Liu, Na Chen, Jingwei Wang, Cheng Wang, Jiansheng Liu, S L Chin, Zhizhan Xu
Artificial rainmaking is in strong demand especially in arid regions. Traditional methods of seeding various Cloud Condensation Nuclei (CCN) into the clouds are costly and not environment friendly. Possible solutions based on ionization were proposed more than 100 years ago but there is still a lack of convincing verification or evidence. In this report, we demonstrated for the first time the condensation and precipitation (or snowfall) induced by a corona discharge inside a cloud chamber. Ionic wind was found to have played a more significant role than ions as extra CCN...
September 18, 2017: Scientific Reports
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