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https://www.readbyqxmd.com/read/28202732/atomic-structure-of-granulin-determined-from-native-nanocrystalline-granulovirus-using-an-x-ray-free-electron-laser
#1
Cornelius Gati, Dominik Oberthuer, Oleksandr Yefanov, Richard D Bunker, Francesco Stellato, Elaine Chiu, Shin-Mei Yeh, Andrew Aquila, Shibom Basu, Richard Bean, Kenneth R Beyerlein, Sabine Botha, Sébastien Boutet, Daniel P DePonte, R Bruce Doak, Raimund Fromme, Lorenzo Galli, Ingo Grotjohann, Daniel R James, Christopher Kupitz, Lukas Lomb, Marc Messerschmidt, Karol Nass, Kimberly Rendek, Robert L Shoeman, Dingjie Wang, Uwe Weierstall, Thomas A White, Garth J Williams, Nadia A Zatsepin, Petra Fromme, John C H Spence, Kenneth N Goldie, Johannes A Jehle, Peter Metcalf, Anton Barty, Henry N Chapman
To understand how molecules function in biological systems, new methods are required to obtain atomic resolution structures from biological material under physiological conditions. Intense femtosecond-duration pulses from X-ray free-electron lasers (XFELs) can outrun most damage processes, vastly increasing the tolerable dose before the specimen is destroyed. This in turn allows structure determination from crystals much smaller and more radiation sensitive than previously considered possible, allowing data collection from room temperature structures and avoiding structural changes due to cooling...
February 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28199463/effect-of-methyl-aminolevulinate-photodynamic-therapy-with-and-without-ablative-fractional-laser-treatment-in-patients-with-microinvasive-squamous-cell-carcinoma-a-randomized-clinical-trial
#2
Seung-Hwan Choi, Ki-Ho Kim, Ki-Hoon Song
Importance: Surgical excision is the standard treatment for cutaneous squamous cell carcinoma (SCC). However, microinvasive SCC (Clark level II) is limited to the papillary dermis, and it should be differentiated from invasive SCC. Ablative fractional laser-primed photodynamic therapy (AFL-PDT) may have enhanced efficacy. Objective: To compare 1 session of AFL-PDT with 2 sessions of conventional methyl aminolevulinate-PDT (MAL-PDT) for the treatment of microinvasive SCC...
February 15, 2017: JAMA Dermatology
https://www.readbyqxmd.com/read/28195278/influence-of-the-excitation-light-intensity-on-the-rate-of-fluorescence-quenching-reactions-pulsed-experiments
#3
Gonzalo Angulo, Jadwiga Milkiewicz, Daniel Kattnig, Michał Nejbauer, Yuriy Stepanenko, Jan Szczepanek, Czesław Radzewicz, Paweł Wnuk, Günter Grampp
The effect of multiple light excitation events on bimolecular photo-induced electron transfer reactions in liquid solution is studied experimentally. It is found that the decay of fluorescence can be up to 25% faster if a second photon is absorbed after a first cycle of quenching and recombination. A theoretical model is presented which ascribes this effect to the enrichment of the concentration of quenchers in the immediate vicinity of fluorophores that have been previously excited. Despite its simplicity, the model delivers a qualitative agreement with the observed experimental trends...
February 14, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28176823/volumetric-spatial-correlations-of-neurovascular-coupling-studied-using-single-pulse-opto-fmri
#4
Isabel N Christie, Jack A Wells, Sergey Kasparov, Alexander V Gourine, Mark F Lythgoe
Neurovascular coupling describes the link between neuronal activity and cerebral blood flow. This relationship has been the subject of intense scrutiny, with most previous work seeking to understand temporal correlations that describe neurovascular coupling. However, to date, the study of spatial correlations has been limited to two-dimensional mapping of neuronal or vascular derived signals emanating from the brain's surface, using optical imaging techniques. Here, we investigate spatial correlations of neurovascular coupling in three dimensions, by applying a single 10 ms pulse of light to trigger optogenetic activation of cortical neurons transduced to express channelrhodopsin2, with concurrent fMRI...
February 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28164458/comparison-of-hair-removal-efficacy-and-side-effect-of-neodymium-yttrium-aluminum-garnet-laser-and-intense-pulsed-light-systems-18-month-follow-up
#5
Georgina Zita Szima, Eszter Anna Janka, Anikó Kovács, Blanka Bortély, Edina Bodnár, Irina Sawhney, Éva Szabó, Éva Remenyik
BACKGROUND: Photothermal destruction of hair shaft melanin with intense pulsed light (IPL) and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser has become an effective treatment of hair removal. AIMS: Our aim was to compare efficacy, satisfactory levels, safety, and side effects of Nd:YAG and IPL in hair reduction. METHODS: This was a prospective randomized intrapatient, right-left, assessor-blinded comparison of Nd:YAG vs IPL. There were 38 volunteers recruited...
February 6, 2017: Journal of Cosmetic Dermatology
https://www.readbyqxmd.com/read/28163457/near-infrared-pulsed-light-for-permanent-hair-reduction-in-fitzpatrick-skin-types-iv-and-v
#6
Pratik Thacker, Pramod Kumar
BACKGROUND: Excessive hair on the face is a significant cause for distress amongst women. Permanent hair reduction methods including lasers and pulsed light devices are increasingly being used. AIMS: The aim of this study is to evaluate the efficacy and safety of near infrared pulsed light source for permanent hair reduction in women seeking treatment for excessive hair growth on the upper lip and chin. SETTINGS AND DESIGN: This was a prospective observational study done at a tertiary care hospital in South India...
October 2016: Journal of Cutaneous and Aesthetic Surgery
https://www.readbyqxmd.com/read/28157369/perturbative-high-harmonic-wave-front-control
#7
Zhengyan Li, Graham Brown, Dong Hyuk Ko, Fanqi Kong, Ladan Arissian, P B Corkum
We pattern the wave front of a high harmonic beam by intersecting the intense driving laser pulse that generates the high harmonic with a weak control pulse. To illustrate the potential of wave-front control, we imprint a Fresnel zone plate pattern on a harmonic beam, causing the harmonics to focus and defocus. The quality of the focus that we achieve is measured using the spectral wave-front optical reconstruction by diffraction method. We will show that it is possible to enhance the peak intensity by orders of magnitude without a physical optical element in the path of the extreme ultraviolet (XUV) beam...
January 20, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28146354/selective-light-induced-patterning-of-carbon-nanotube-silver-nanoparticle-composite-to-produce-extremely-flexible-conductive-electrodes
#8
Inhyuk Kim, Kyoohee Woo, Zhaoyang Zhong, Eonseok Lee, Dongwoo Kang, Sunho Jeong, Young-Man Choi, Yunseok Jang, Sin Kwon, Jooho Moon
Recently, highly flexible conductive features have been widely demanded for the development of various electronic applications, such as foldable displays, deformable lighting, disposable sensors, and flexible batteries. Herein, we report for the first time a selective photonic sintering-derived, highly reliable patterning approach for creating extremely flexible carbon nanotube (CNT)/silver nanoparticle (Ag NP) composite electrodes that can tolerate severe bending (20 000 cycles at a bending radius of 1 mm)...
February 10, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28125779/monolayer-ws2-nanopores-for-dna-translocation-with-light-adjustable-sizes
#9
Gopinath Danda, Paul Masih Das, Yung-Chien Chou, Jerome T Mlack, William M Parkin, Carl H Naylor, Kazunori Fujisawa, Tianyi Zhang, Laura Beth Fulton, Mauricio Terrones, Alan T Charlie Johnson, Marija Drndić
Two-dimensional materials are promising for a range of applications, as well as testbeds for probing the physics of low-dimensional systems. Tungsten disulfide (WS2) monolayers exhibit a direct band gap and strong photoluminescence (PL) in the visible range, opening possibilities for advanced optoelectronic applications. Here, we report the realization of two-dimensional nanometer-size pores in suspended monolayer WS2 membranes, allowing for electrical and optical response in ionic current measurements. A focused electron beam was used to fabricate nanopores in WS2 membranes suspended on silicon-based chips and characterized using PL spectroscopy and aberration-corrected high-resolution scanning transmission electron microscopy...
February 1, 2017: ACS Nano
https://www.readbyqxmd.com/read/28122416/gain-with-no-pain-pain-management-in-dermatological-photodynamic-therapy
#10
REVIEW
B Wang, L Shi, Y F Zhang, Q Zhou, J Zheng, R M Szeimies, X L Wang
Pain during photodynamic therapy (PDT) is the main limiting adverse effect in its use in dermatology. Given its multifactorial nature, we reviewed both intrinsic and extrinsic factors that are involved in PDT pain. We proposed a threshold theory for pain experience in PDT: it positively correlates with fluence rate and dose below certain threshold (rate of ~60 mW/cm(2) , dose of ~50 J/cm(2) ); when threshold is surpassed, pain intensity no longer increases. Additionally, we carefully compared recent updates on pain management strategies and we suggested that cold air analgesia and low-irradiance light source (such as intense pulsed light and day-light PDTs) represent the current best analgesic options...
January 25, 2017: British Journal of Dermatology
https://www.readbyqxmd.com/read/28122296/comparative-analysis-of-mutant-plants-impaired-in-the-main-regulatory-mechanisms-of-photosynthetic-light-reactions-from-biophysical-measurements-to-molecular-mechanisms
#11
Mikko Tikkanen, Sanna Rantala, Michele Grieco, Eva-Mari Aro
Chlorophyll (chl) fluorescence emission by photosystem II (PSII) and light absorption by P700 reaction center chl a of photosystem I (PSI) provide easy means to probe the function of the photosynthetic machinery. The exact relationship between the measured optical variables and the molecular processes have, however, remained elusive. Today, the availability of mutants with distinct molecular characterization of photosynthesis regulatory processes should make it possible to gain further insights into this relationship, yet a systematic comparative analysis of such regulatory mutants has been missing...
January 17, 2017: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/28121246/associations-of-objectively-measured-physical-activity-and-sedentary-time-with-arterial-stiffness-in-pre-pubertal-children
#12
Eero A Haapala, Juuso Väistö, Aapo Veijalainen, Niina Lintu, Petri Wiklund, Kate Westgate, Ulf Ekelund, Virpi Lindi, Soren Brage, Timo A Lakka
PURPOSE: To investigate the relationships of objectively measured physical activity (PA) and sedentary time (ST) to arterial stiffness in pre-pubertal children. METHOD: Altogether 136 children (57 boys, 79 girls) aged 6-8-years participated in the study. Stiffness index (SI) was assessed by pulse contour analysis based on photoplethysmography. ST, light PA, moderate PA, and vigorous PA were assessed using combined acceleration and heart rate monitoring. We investigated the associations of ST (<1...
January 25, 2017: Pediatric Exercise Science
https://www.readbyqxmd.com/read/28106423/amplification-of-relativistic-electron-bunches-by-acceleration-in-laser-fields
#13
J Braenzel, A A Andreev, F Abicht, L Ehrentraut, K Platonov, M Schnürer
Direct acceleration of electrons in a coherent, intense light field is revealed by a remarkable increase of the electron number in the MeV energy range. Laser irradiation of thin polymer foils with a peak intensity of ∼1×10^{20}  W/cm^{2} releases electron bunches along the laser propagation direction that are postaccelerated in the partly transmitted laser field. They are decoupled from the laser field at high kinetic energies, when a second foil target at an appropriate distance prevents their subsequent deceleration in the declining laser field...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28098455/angular-dependence-of-ionization-by-circularly-polarized-light-calculated-with-time-dependent-configuration-interaction-with-an-absorbing-potential
#14
Paul Hoerner, H Bernhard Schlegel
The angular dependence of ionization by linear and circularly polarized light has been examined for N2, NH3, H2O, CO2, CH2O, pyrazine, methyloxirane, and vinyloxirane. Time-dependent configuration interaction with single excitations and a complex absorbing potential was used to simulate ionization by a seven cycle 800 nm cosine squared pulse with intensities ranging from 0.56 × 10(14) to 5.05 × 10(14) W cm(-2). The shapes of the ionization yield for linearly polarized light can be understood primarily in terms of the nodal structure of the highest occupied orbitals...
February 3, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28092628/ultrafast-adiabatic-second-harmonic-generation
#15
Asaf Dahan, Assaf Levanon, Mordechai Katz, Haim Suchowski
We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research...
March 1, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28075562/evidence-for-a-di-%C3%AE-oxo-diamond-core-in-the-mn-iv-fe-iv-activation-intermediate-of-ribonucleotide-reductase-from-chlamydia-trachomatis
#16
Ryan J Martinie, Elizabeth J Blaesi, Carsten Krebs, J Martin Bollinger, Alexey Silakov, Christopher J Pollock
High-valent iron and manganese complexes effect some of the most challenging biochemical reactions known, including hydrocarbon and water oxidations associated with the global carbon cycle and oxygenic photosynthesis, respectively. Their extreme reactivity presents an impediment to structural characterization, but their biological importance and potential chemical utility have, nevertheless, motivated extensive efforts toward that end. Several such intermediates accumulate during activation of class I ribonucleotide reductase (RNR) β subunits, which self-assemble dimetal cofactors with stable one-electron oxidants that serve to initiate the enzyme's free-radical mechanism...
January 27, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28071852/environmental-and-excitation-power-effects-on-the-ratiometric-upconversion-luminescence-based-temperature-sensing-using-nanocrystalline-nayf4-yb3-er3
#17
Iko Hyppänen, Niina Perälä, Riikka Arppe, Michael Schäferling, Tero Soukka
The luminescence intensity ratio (LIR) of the green emissions of the near-infrared excited NaYF4:Yb3+,Er3+ nanocrystals is a promising method for temperature sensing. Here, the influence of excitation power density, excitation pulse length, excitation wavelength, silica shell, and solvent on the LIR and its temperature response is reported. Primary objective is to study the LIR mechanism and the impact of measurement and environmental parameters on the calibration and precision of the LIR. The LIR value is demonstrated to be unaffected by the excitation intensity in the studied range...
January 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28071681/increased-impedance-near-cut-off-in-plasma-like-media-leading-to-emission-of-high-power-narrow-bandwidth-radiation
#18
M S Hur, B Ersfeld, A Noble, H Suk, D A Jaroszynski
Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity...
January 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28069205/study-of-a-laboratory-scaled-new-method-for-the-accelerated-continuous-ageing-of-wine-spirits-by-applying-ultrasound-energy
#19
M J Delgado-González, M M Sánchez-Guillén, M V García-Moreno, M C Rodríguez-Dodero, C García-Barroso, D A Guillén-Sánchez
During the ageing of brandies, many physicochemical processes take place involving the distilled spirit and the wood of the casks. Because of these reactions, the polyphenolic content of brandies and their content of organic acids increase with the ageing. These reactions are slow, and the ageing of high-quality brandies takes several years. In this paper, the development of a system that uses the circulation of the wine distillate through encapsulated American oak chips and the application of ultrasound energy with the aim of producing aged wine spirits has been carried out, and the influences of the operation variables over the characteristics of the produced drink have been measured...
May 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28067265/laser-printed-nano-gratings-orientation-and-period-peculiarities
#20
Valdemar Stankevič, Gediminas Račiukaitis, Francesca Bragheri, Xuewen Wang, Eugene G Gamaly, Roberto Osellame, Saulius Juodkazis
Understanding of material behaviour at nanoscale under intense laser excitation is becoming critical for future application of nanotechnologies. Nanograting formation by linearly polarised ultra-short laser pulses has been studied systematically in fused silica for various pulse energies at 3D laser printing/writing conditions, typically used for the industrial fabrication of optical elements. The period of the nanogratings revealed a dependence on the orientation of the scanning direction. A tilt of the nanograting wave vector at a fixed laser polarisation was also observed...
January 9, 2017: Scientific Reports
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