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Juan Prieto-Pena, Faustino Gomez, Diego M Gonzalez-Castano, Maria Teresa Flores Arias, Justo Arines, Carmen Bao-Varela, Ferran Cambronero-López, Alejandra Martínez Maqueira
Present work describes the radiation quality and dosimetric characterization performed on the micromachining station of the femtosecond STELA (Santiago TErawattLAser) of the University of Santiago de Compostela (Spain). For this aim, ionisation chambers, solid state detectors and radiochromic films were used. The results show the emission of pulsed X-ray produced by laser-accelerated electrons from the ablated material exhibiting both bremsstrahlung and characteristic radiation. Although this radiation was produced unintentionally, a high superficial dose rate can be achieved...
March 13, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
Jorge Follana-Berná, Sairaman Seetharaman, Luis Martín-Gomis, Georgios Charalambidis, Adelais Trapali, Paul A Karr, Athanassios G Coutsolelos, Fernando Fernández-Lázaro, Francis D'Souza, Ángela Sastre-Santos
A new zinc phthalocyanine-zinc porphyrin dyad (ZnPc-ZnP) fused through a pyrazine ring has been synthesized as a receptor for imidazole-substituted C60 (C60 Im) electron acceptor. Self-assembly via metal-ligand axial coordination and the pertinent association constants in solution were determined by1 H-NMR, UV-Vis and fluorescence titration experiments at room temperature. The designed host was able to bind up to two C60 Im electron acceptor guest molecules to yield C60 Im:ZnPc-ZnP:ImC60 donor-acceptor supramolecular complex...
March 5, 2018: Physical Chemistry Chemical Physics: PCCP
Enrico Perfetto, Davide Sangalli, Andrea Marini, Gianluca Stefanucci
The early stage density oscillations of the electronic charge in molecules irradiated by an attosecond XUV pulse takes place on femto- or subfemtosecond timescales. This ultrafast charge migration process is a central topic in attoscience as it dictates the relaxation pathways of the molecular structure. A predictive quantum theory of ultrafast charge migration should incorporate the atomistic details of the molecule, electronic correlations and the multitude of ionization channels activated by the broad-bandwidth XUV pulse...
March 1, 2018: Journal of Physical Chemistry Letters
A D Anastasiou, S Strafford, C L Thomson, J Gardy, T J Edwards, M Malinowski, S A Hussain, N K Metzger, A Hassanpour, C T A Brown, A P Brown, M S Duggal, A Jha
A radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe3+ -doped calcium phosphate minerals (specifically in this work fluorapatite powder containing Fe2 O3 nanoparticles (NP)). A layer of the synthetic powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0...
February 17, 2018: Acta Biomaterialia
Xuemin Wang, Rui Wang, Li Shen, Zhaofeng Tang, Congying Wen, Bin Dong, Heyuan Liu, Chunfeng Zhang, Xiyou Li
A covalently linked tetracene trimer with a "face-to-face" stacked structure was prepared and its molecular structure is characterized by 1H NMR, MALDI-TOF mass spectroscopy, and elemental analysis. The minimized molecular structure reveals that three tetracene subunits within this trimer adopt a partially "face-to-face" stacked configuration. Its absorption spectrum differs significantly from that of the monomeric and dimeric counterparts in solution due to the strong ground state interactions between the neighboring tetracene subunits...
February 13, 2018: Physical Chemistry Chemical Physics: PCCP
Zhi-Yuan Cheng, Ting Ye, Qiu-Yang Ling, Ting Wu, Gang-Yong Wu, Gang-Jun Zong
Vascular calcification (VC) occurs in patients with chronic kidney disease (CKD) and contributes to cardiovascular dysfunction and mortality. Parathyroid hormone (PTH) is a crucial regulator of VC. High PTH serum levels constitute as a major risk factor for patients with CKD. However, the effect and mechanism of PTH on osteoblastic differentiation in endothelial cells have not been fully elucidated. In the present study, the role of PTH in VC was investigated using an in vitro calcification model. Endothelial cells were stimulated with PTH in the femto- to picomolar range...
February 2018: Experimental and Therapeutic Medicine
Leonie Wibmer, Sebastian Lages, Tobias Unruh, Dirk M Guldi
Herein, various dispersions of MoS2 obtained by means of liquid phase exfoliation are spectroscopically, (spectro-) electrochemically, and microscopically characterized. At the core of these studies are transient absorption assays. Importantly, small-angle X-ray scattering measurements are employed to corroborate the exfoliated character of the MoS2 flakes in dispersion, on the one hand, and to correlate the results with TEM, AFM, and Raman characterization in the solid state, on the other. It is, then, demonstrated that transient absorption spectroscopy responds sensitively not only to changes in the sample preparation but also to instrumental and environmental parameters...
February 7, 2018: Advanced Materials
A T Gardiner, D M Niedzwiedzki, R J Cogdell
Typical purple bacterial photosynthetic units consist of light harvesting one/reaction centre 'core' complexes surrounded by light harvesting two complexes. Factors such as the number and size of photosynthetic units per cell, as well as the type of light harvesting two complex that is produced, are controlled by environmental factors. In this paper, the change in the type of LH2 present in the Rhodopsuedomonas acidophila strain 7050 is described when cells are grown at a range of different light intensities...
January 22, 2018: Faraday Discussions
Wen-Hsuan Kuan, Li-Ting Kao, Jing-Yun Wang, Kuei-Huei Lin
We report a passively mode-locked erbium-doped fiber laser with pulse widths switchable from 473 fs to 76.8 ns, where the fundamental mode-locking, noise-like pulse, nanosecond mode-locking, and dual-width mode-locking (DML) are obtained by adjusting a polarization controller. Co-existence of femto- and nano-second pulses in DML is attributed to the gain balancing. Analytic modeling of the fiber laser with the cubic-quintic Ginzburg-Landau equation is presented, in which the pulse widths are calculated as functions of dispersion, self-phase modulation (SPM), cubic saturable absorption (SA), and quintic SA...
January 15, 2018: Optics Letters
K Dirian, S Bauroth, A Roth, Z Syrgiannis, F Rigodanza, M Burian, H Amenitsch, D I Sharapa, M Prato, T Clark, D M Guldi
The aggregation and the photophysics of a water soluble perylenediimide (PDI) derivative that features two bromine substituents in the bay positions has been probed. Non-fluorescent aggregates were found to be present at concentrations of 1.0 × 10-5 M. In situ small-angle X-ray scattering (SAXS) measurements and complementary molecular modeling showed the presence of PDI aggregates. In their singlet excited states, the PDI aggregates are characterized by distinct transient fingerprints and rapid deactivation, as revealed by pump-probe experiments on the femto-, pico-, nano-, and microsecond timescales...
January 12, 2018: Nanoscale
Anna Zieleniewska, Shannon Harper, Dennis Arnold, Dirk Michael Guldi
At the focal point of this work was photophysical characterization of three meso-meso two-atom-bridged diporphyrins (1-3). Detailed investigations by means of cyclic voltammetry, absorption, fluorescence, and femto-/nano-second transient absorption spectroscopy revealed the discrepancy in electronic communication in a series of meso-meso two-atom-bridged porphyrins in the ground state and in the excited state. In the ground state, the azo-bridge facilitates the strongest electronic communication between the two porphyrins...
January 4, 2018: Chemistry: a European Journal
Min-Ji Kang, Yong-Eun Lee, Jun-Sub Choi, Choun-Ki Joo
In femtosecond laser-assisted cataract surgery, the parameter such as horizontal spot spacing and energy level can be adjusted. Although there have been several studies reported on various laser systems, showing the effects of varying energy levels and horizontal spot spacing on lens capsulotomy cut edges, none have been reported on the Catalys laser system (Abbott Medical Optics, Inc., Santa Ana, CA). The aim of this study is to evaluate, using scanning electron microscopy (SEM), the quality of the cut edges of the laser lens capsulotomy obtained using the Catalys Laser System, using different horizontal spot spacing and energy levels, and to determine the ideal parameters based on SEM results...
2018: PloS One
Yusaku Hontani, Matthias Broser, Arita Silapetere, Benjamin S Krause, Peter Hegemann, John T M Kennis
Anion channelrhodopsins (ACRs) are of great interest due to their ability to inhibit electrical signaling in optogenetic experiments. The photochemistry of ACRs is currently poorly understood and an improved understanding would be beneficial for rational design of ACRs with modified properties. Activation/deactivation of ACRs involves a series of photoreactions ranging from femtoseconds to seconds, thus real-time observation is essential to comprehend the full complexity of the photochemical processes. Here we investigate the photocycle of an ACR from Proteomonas sulcata (PsACR1), which is valuable for optogenetic applications due to the red-shifted absorption and action spectra compared to the prototype ACRs from Guillardia theta: GtACR1 and GtACR2, and the fast channel closing properties...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
Taito Osaka, Takashi Hirano, Yuki Morioka, Yasuhisa Sano, Yuichi Inubushi, Tadashi Togashi, Ichiro Inoue, Kensuke Tono, Aymeric Robert, Kazuto Yamauchi, Jerome B Hastings, Makina Yabashi
Temporal coherence is one of the most fundamental characteristics of light, connecting to spectral information through the Fourier transform relationship between time and frequency. Interferometers with a variable path-length difference (PLD) between the two branches have widely been employed to characterize temporal coherence properties for broad spectral regimes. Hard X-ray interferometers reported previously, however, have strict limitations in their operational photon energies, due to the specific optical layouts utilized to satisfy the stringent requirement for extreme stability of the PLD at sub-ångström scales...
November 1, 2017: IUCrJ
Zhenjie Wu, Rui Yang, Di Zu, Shuqing Sun
The development of highly sensitive and rapid methods for detecting DNA is of critical importance. Here, we describe a strategy for the digital detection of target DNA at the femto-molar level. Individual DNA molecules were encoded with a single gold nanorod (AuNR), separated and enriched by magnetic immune-separation. The coding gold nanorods were then de-hybridized and dispersed into a gold nanosphere (AuNS) solution at a certain concentration, and both gold nanoparticles were immobilized on glass slides for dark-field microscopic imaging...
November 7, 2017: Scientific Reports
Suhee Kim, Jeong Won Park, Alastair W Wark, Sung Hwa Jhung, Hye Jin Lee
The multiplexed detection of protein biomarkers in plasma present over a range of clinically relevant concentrations continues to be difficult for surface-based bioaffinity detection platforms such as surface plasmon resonance (SPR). As well as nonspecific adsorption, challenges include quantitative comparison between targets whose concentrations differ by orders of magnitude, regenerating SPR chips after plasma exposure, and the two- or four-channel limitation of many commercial SPR instruments limiting sample throughput...
November 7, 2017: Analytical Chemistry
Mohammad Ghoreishi, Afsaneh Naderi Beni, Zahra Naderi Beni, Alireza Zandi, Farzan Kianersi
The purpose of this study is to compare visual outcomes of myopic refractive surgery, using tissue saving (TS), a standard ablation profile by a Technolas 217z100, and aberration smart ablation (ASA), an aspheric algorithm by a MEL 80 excimer laser in two eyes of one patient. In this prospective interventional paired-eye controlled study, a total of 100 eyes of 50 participants with myopia with or without astigmatism underwent thin-flap Femto-LASIK, using a Femto LDV femtosecond laser (Ziemer Ophthalmic Systems AG, Port, Switzerland)...
December 2017: Lasers in Medical Science
Jing Zhang, Yue-Hua Zhou, Yan Zheng, Qian Liu
AIM: To compare the speed of visual recovery following myopic thin-flap LASIK with four femtosecond lasers. METHODS: Eighty-eight eyes of 46 patients who were consecutively scheduled for bilateral LASIK with the IntraLase FS60 (Group 1), Femto LDV Crystal Line (Group 2), Wavelight FS200 (Group 3) and VisuMax (Group 4) femtosecond lasers were enrolled in. Monocular uncorrected distance visual acuity (UDVA), best-corrected distant visual acuity (CDVA), refraction, contrast sensitivity and higher-order aberrations (HOAs) were evaluated at 1, 3d, 1wk and 1mo postoperatively...
2017: International Journal of Ophthalmology
Apeng Chen, Kyle B Lynch, Jiangtao Ren, Zhijian Jia, Yu Yang, Joann J Lu, Shaorong Liu
Single-cell analysis has attracted increasing attention because of cell heterogeneities. Various strategies have been developed for analyzing single cells, but most of these analytical processes kill the cells. Tools that can qualitatively and quantitatively measure the cellular contents without killing the cell are highly demanding because they enable us to conduct single-cell time-course studies (e.g., to examine how a cell responds to a therapy before, during, and after a treatment). Here we develop a femto-liter (fL) pipet to serve this purpose...
October 4, 2017: Analytical Chemistry
Maria Carmina Scala, Marina Sala, Agostina Pietrantoni, Antonia Spensiero, Simone Di Micco, Mariangela Agamennone, Alessia Bertamino, Ettore Novellino, Giuseppe Bifulco, Isabel M Gomez-Monterrey, Fabiana Superti, Pietro Campiglia
Bovine lactoferrin is a biglobular multifunctional iron binding glycoprotein that plays an important role in innate immunity against infections. We have previously demonstrated that selected peptides from bovine lactoferrin C-lobe are able to prevent both Influenza virus hemagglutination and cell infection. To deeper investigate the ability of lactoferrin derived peptides to inhibit Influenza virus infection, in this study we identified new bovine lactoferrin C-lobe derived sequences and corresponding synthetic peptides were synthesized and assayed to check their ability to prevent viral hemagglutination and infection...
September 6, 2017: Scientific Reports
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