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# Lasers

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#1
Jun Tao, Meng Dang, Xiaodan Su, Qing Hao, Junjie Zhang, Xiaobo Ma, Guangming Lu, Yunlei Zhang, Ying Tian, Lixing Weng, Zhaogang Teng, Lianhui Wang
In the work, yolk-shell structured mesoporous organosilica nanoparticles (YSMONs) are successfully prepared by a mild alkalescent etching approach. The method is very convenient, in which mesostructured organosilica nanospheres are directly transformed into yolk-shell structures after etching with mild alkalescent solution (e.g. sodium carbonate solution). The prepared YSMONs have ethane-bridged frameworks, a monodisperse diameter (320 nm), a large pore volume (1.0 cm3  g-1 ), a uniform mesopore (2.4 nm) and a high surface area (1327 m2  g-1 )...
May 15, 2018: Journal of Colloid and Interface Science
#2
Catherine P Whitby, Melinda Krebsz, Samuel J Booty
HYPOTHESIS: Fumed silica particles are thought to thicken organic solvents into gels by aggregating to form networks. Hydrogen bonding between silanol groups on different particle surfaces causes the aggregation. The gel structure and hence flow behaviour is altered by varying the proportion of silanol groups on the particle surfaces. However, characterising the gel using rheology measurements alone is not sufficient to optimise the aggregation. We have used confocal microscopy to characterise the changes in the network microstructure caused by altering the particle surface chemistry...
May 12, 2018: Journal of Colloid and Interface Science
#3
Spencer T Brinker, Steven P Kearney, Thomas J Royston, Dieter Klatt
The mechanical properties of tissue are sensitive to pathological changes, which is the basis for using dynamic elastography as a diagnostic tool. The purpose of this study is a concurrent cross-modality comparison of two dynamic elastography methods, Magnetic Resonance Elastography (MRE) and Scanning Laser Doppler Vibrometry (SLDV) using a single vibration source method. Cylindrical soft tissue mimicking specimens of Plastisol and Ecoflex are stimulated with 60, 100, 150, and 250 Hz sinusoidal vibration during imaging...
May 8, 2018: Journal of the Mechanical Behavior of Biomedical Materials
#4
Lingli Hu, Zhencheng Liao, Qiqi Hu, Katherine G Maffucci, Yan Qu
Dissolving microneedles (MNs) have been widely studied for their applications in effective transdermal drug delivery due to their ability to dissolve within the skin. This study details the first reported successful preparation of novel dissolving MNs using Bletilla striata polysaccharide (BSP), a natural glucomannan material, and investigates the potential for using such MNs as a transdermal drug delivery vector. The prepared dissolving Bletilla striata polysaccharide microneedles (BMNs) had excellent moldability and were easily detached from the mold...
May 15, 2018: International Journal of Biological Macromolecules
#5
Siham Akmoussi-Toumi, Souad Khemili-Talbi, Imen Ferioune, Salima Kebbouche-Gana
The present study investigates the purification and biochemical characterization of an extracellular lipase (HML) from Haloarchaea Haloferax mediterranei strain ATS1, isolated from the Sebkha (Medea, Algeria). The pure protein was obtained with ammonium sulfate precipitation (40-70%)-dialysis and UNO Q-6 FPLC, and characterized biochemically. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis revealed that the purified enzyme was a monomer, with a molecular mass of 45,011...
May 15, 2018: International Journal of Biological Macromolecules
#6
Fumiyasu Endo, Kazuhiro Ohwaki, Masaki Shimbo, Kazunori Hattori
OBJECTIVES: To evaluate the relationship between the lengths of two regions of the intraprostatic urethral sphincter, the distal region (from the apex to the adenoma; AA) and the proximal region (from the adenoma to the verumontanum; AV) and prostate volume (PV) in patients with clinical benign prostate hyperplasia. METHODS: A total of 110 patients who underwent magnetic resonance imaging (MRI) prior to holmium laser enucleation of the prostate were enrolled. The lengths of two distinct intraprostatic urethral regions were measured on MRI, and we used multiple regression analysis to explore the association between these lengths and PV...
May 15, 2018: Urology
#7
Dyah Paramita, J D P Wisnubroto
BACKGROUND: Methylglyoxal (MG) is an extremely reactive α-ketoaldehyde endogenously produced by various metabolic pathways, including the dephosphorylation of glycolytic intermediates, metabolites of the polyol pathway, and aminoacetone metabolism. MG cytotoxicity occurs through the induction of apoptosis. There are multiple mechanisms by which MG can induce apoptosis, e.g., through the generation of reactive oxygen species (ROS), induction of oxidative DNA damage, or accumulation of a specific MG-derived advanced glycation end product (AGE)...
May 15, 2018: Experimental and Molecular Pathology
#8
Steffen Stein, Michael Schauseil, Andreas Hellak, Heike Korbmacher-Steiner, Andreas Braun
OBJECTIVE: The objective of this split-mouth trial was to investigate the influence of photobiomodulation therapy (PBMT) on adjuvant treatment of gingivitis induced by multi-bracket appliances, after bracket debonding and professional tooth cleaning. MATERIALS AND METHODS: Thirteen patients (mean age 16.15 years; standard deviation ±2.12 years) who had completed active orthodontic treatment with fixed orthodontic appliances in an orthodontic clinic were included on a randomized basis...
May 18, 2018: Photomedicine and Laser Surgery
#9
Sebastian Stach, Olga Kędzia, Żaneta Garczyk, Zygmunt Wróbel
The main goal of the study was to develop a model of the degree of surface porosity of a biomaterial intended for implants. The model was implemented using MATLAB. A computer simulation was carried out based on the developed model, which resulted in a two-dimensional image of the modelled surface. Then, an algorithm for computerised image analysis of the surface of the actual oxide bioceramic layer was developed, which enabled determining its degree of porosity. In order to obtain the confocal micrographs of a few areas of the biomaterial, measurements were performed using the LEXT OLS4000 confocal laser microscope...
May 18, 2018: Biomedizinische Technik. Biomedical Engineering
#10
Anselm A Derda, Chin Cheng Woo, Thidathip Wongsurawat, Mark Richards, Chuen Neng Lee, Theo Kofidis, Vladimir A Kuznetsov, Vitaly A Sorokin
Myocardial infarction (MI) induced by acute coronary arterial occlusion is usually secondary to atherosclerotic plaque rupture. Dysregulated response of vascular smooth muscle cells (VSMCs) in atherosclerotic plaques may promote plaque rupture. Cadherins (CDHs) form adherens junctions and are known stabilizers of atherosclerotic plaques. To date, the expression patterns of cadherin have not been well investigated in MI aortic VSMCs. We aimed to investigate the expression of cadherin genes in the aortic wall of patients with and without MI...
May 18, 2018: Physiological Genomics
#11
J K Wahlstrand, S Zahedpour, A Bahl, M Kolesik, H M Milchberg
We present absolute space- and time-resolved measurements of the ultrafast laser-driven nonlinear polarizability in argon, krypton, xenon, nitrogen, and oxygen up to ionization fractions of a few percent. These measurements enable determination of the strongly nonperturbative bound-electron nonlinear polarizability well beyond the ionization threshold, where it is found to remain approximately quadratic in the laser field, a result normally expected at much lower intensities where perturbation theory applies...
May 4, 2018: Physical Review Letters
#12
Hélène Fleurbaey, Sandrine Galtier, Simon Thomas, Marie Bonnaud, Lucile Julien, François Biraben, François Nez, Michel Abgrall, Jocelyne Guéna
We present a new measurement of the 1S-3S two-photon transition frequency of hydrogen, realized with a continuous-wave excitation laser at 205 nm on a room-temperature atomic beam, with a relative uncertainty of 9×10^{-13}. The proton charge radius deduced from this measurement, r_{p}=0.877(13)  fm, is in very good agreement with the current CODATA-recommended value. This result contributes to the ongoing search to solve the proton charge radius puzzle, which arose from a discrepancy between the CODATA value and a more precise determination of r_{p} from muonic hydrogen spectroscopy...
May 4, 2018: Physical Review Letters
#13
Yuan Huang, Xiao Wang, Xu Zhang, Xianjue Chen, Baowen Li, Bin Wang, Ming Huang, Chongyang Zhu, Xuewei Zhang, Wolfgang S Bacsa, Feng Ding, Rodney S Ruoff
Raman spectra of large graphene bubbles showed size-dependent oscillations in spectral intensity and frequency, which originate from optical standing waves formed in the vicinity of the graphene surface. At a high laser power, local heating can lead to oscillations in the Raman frequency and also create a temperature gradient in the bubble. Based on Raman data, the temperature distribution within the graphene bubble was calculated, and it is shown that the heating effect of the laser is reduced when moving from the center of a bubble to its edge...
May 4, 2018: Physical Review Letters
#14
J Braenzel, M D Barriga-Carrasco, R Morales, M Schnürer
We investigate, both experimentally and theoretically, how the spectral distribution of laser accelerated carbon ions can be filtered by charge exchange processes in a double foil target setup. Carbon ions at multiple charge states with an initially wide kinetic energy spectrum, from 0.1 to 18 MeV, were detected with a remarkably narrow spectral bandwidth after they had passed through an ultrathin and partially ionized foil. With our theoretical calculations, we demonstrate that this process is a consequence of the evolution of the carbon ion charge states in the second foil...
May 4, 2018: Physical Review Letters
#15
Neil J Cornish, Logan O'Beirne, Stephen R Taylor, Nicolás Yunes
The opening of the gravitational wave window by ground-based laser interferometers has made possible many new tests of gravity, including the first constraints on polarization. It is hoped that, within the next decade, pulsar timing will extend the window by making the first detections in the nanohertz frequency regime. Pulsar timing offers several advantages over ground-based interferometers for constraining the polarization of gravitational waves due to the many projections of the polarization pattern provided by the different lines of sight to the pulsars, and the enhanced response to longitudinal polarizations...
May 4, 2018: Physical Review Letters
#16
A D Bounds, N C Jackson, R K Hanley, R Faoro, E M Bridge, P Huillery, M P A Jones
We propose and demonstrate the laser cooling and trapping of Rydberg-dressed Sr atoms. By off-resonantly coupling the excited state of a narrow (7 kHz) cooling transition to a high-lying Rydberg state, we transfer Rydberg properties such as enhanced electric polarizability to a stable magneto-optical trap operating at <1  μK. Simulations show that it is possible to reach a regime where the long-range interaction between Rydberg-dressed atoms becomes comparable to the kinetic energy, opening a route to combining laser cooling with tunable long-range interactions...
May 4, 2018: Physical Review Letters
#17
Debkalpa Goswami, Juan Camilo Múnera, Aniket Pal, Behnam Sadri, Caio Lui Paganelli Guzzo Scarpetti, Ramses V Martinez
This letter describes a low-cost, scalable nanomanufacturing process that enables the continuous forming of thin metallic layers with nanoscale accuracy using roll-to-roll, laser-induced superplasticity (R2RLIS). R2RLIS uses a laser shock to induce the ultrahigh strain rate deformation of metallic films at room temperature into low-cost polymeric nanomolds, independently of the original grain size of the metal. This simple and inexpensive nanoforming method does not require access to cleanrooms and associated facilities, and can be easily implemented on conventional CO2 lasers, enabling laser systems commonly used for rapid prototyping or industrial cutting and engraving to fabricate uniform and three-dimensional crystalline metallic nanostructures over large areas...
May 18, 2018: Nano Letters
#18
Mate Szarka, Szabolcs Szilasi, Boglarka Donczo, Daniel Sarkozy, Istvan Rajta, Andras Guttman
On a roundtrip to Mars, astronauts are expectedly exposed to an approximate amount of radiation that exceeds the lifetime limits on Earth. This elevated radiation dose is mainly due to Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE). Specific patterns of the N-glycosylation of human immunoglobulins have already been associated with various ailments such as autoimmune diseases, malignant transformation, chronic inflammation and ageing. The focus of our work was to investigate the effect of low-energy proton irradiation on the IgG N-glycosylation profile with the goal if disease associated changes could be detected during space travel and not altered by space radiation...
May 18, 2018: Electrophoresis
#19
Minghua Zhang, Jiyong Fu, A C Dias, Fanyao Qu
We present a theory to address the photoluminescence (PL) intensity and valley polarization (VP) dynamics in monolayer WSe$_2$, under the impact of excitonic dark states of both excitons and biexcitons. We find that the PL intensity of all excitonic channels including intravalley exciton (X$_{\rm b}$), intravalley biexciton (XX$_{\rm k,k}$) and intervalley biexciton (XX$_{\rm k,k^\prime}$) in particular for the {XX$_{\rm k,k}$} PL is enhanced by laser excitation fluence. In addition, our results indicate the anomalous temperature dependence of PL, i...
May 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#20
Y T Wang, X Sun, W Y Ji
Objective: To assess the efficacy of partial CO₂ laser arytenoidectomy in cases with bilateral vocal fold paralysis. Method: A total number of 11 patients with bilateral vocal fold paralysis who undergone partial CO₂ laser arytenoidectomy was included in this retrospective study. The efficacy of the treatment was evaluated by compare the form of glottis, the scale of dyspnea and the change of voice preoperatively and postoperatively, as well as the occurrence of surgery complications such as dysphonia and dysphagia...
February 2018: Journal of Clinical Otorhinolaryngology, Head, and Neck Surgery
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