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Pavel Moreno-García, Valentine Grimaudo, Andreas Riedo, Alena Cedeño López, Reto Wiesendanger, Marek Tulej, Cynthia Gruber, Emanuel Lörtscher, Peter Wurz, Peter Broekmann
State-of-the-art three-dimensional very large-scale integration (3D-VLSI) relies, among other factors, on the purity of high-aspect-ratio Cu interconnects such as through-silicon-vias (TSVs). Accurate spatial chemical analysis of electroplated TSV structures has been proven to be challenging due to their large aspect ratios and their multi-material composition (Cu and Si) with distinct physical properties. Here, we demonstrate that these structures can be accurately analyzed by femto-second (fs) laser beam ablation techniques in combination with ionization mass spectrometry (LIMS)...
May 3, 2018: Analytical Chemistry
Janine Emile, Hervé Tabuteau, Olivier Emile
The rotation of a sub-millimeter size disk over a water bath is reported. The origin of the rotation arises from the transfer of angular momentum from a plane wave diffracted by an asymmetrical picture printed on the disk. Because of its hydrophobic character, the viscous friction contribution to the rotational motion of the object floating on the air/liquid interface is weak. From the driving optical torque and the steady-state rotation, we measure the contribution of the line tension in the femto-Newton range...
May 2, 2018: Soft Matter
J Sanjuan, M Nofrarias
Laser Interferometer Space Antenna (LISA) Pathfinder is a mission to test the technology enabling gravitational wave detection in space and to demonstrate that sub-femto-g free fall levels are possible. To do so, the distance between two free falling test masses is measured to unprecedented sensitivity by means of laser interferometry. Temperature fluctuations are one of the noise sources limiting the free fall accuracy and the interferometer performance and need to be known at the ∼10 μK Hz-1/2 level in the sub-millihertz frequency range in order to validate the noise models for the future space-based gravitational wave detector LISA...
April 2018: Review of Scientific Instruments
Mindaugas Gedvilas, Simonas Indrišiūnas, Bogdan Voisiat, Evaldas Stankevičius, Algirdas Selskis, Gediminas Račiukaitis
Laser interference ablation in silicon using femto-, pico-, and nanosecond pulses was investigated. The experimental and computational results provide information about nanoscale thermal diffusion during the ultra-short laser-matter interaction. The temperature modulation depth was introduced as a parameter for quality assessment of laser interference ablation. Based on the experiments and calculations, a new semi-empirical formula which combines the interference period with the laser pulse duration, the thermal modulation depth and the thermal diffusivity of the material was derived...
April 23, 2018: Physical Chemistry Chemical Physics: PCCP
Frank Sachers, David Goldblum
BACKGROUND: Capsulorhexis is one of the most important steps in cataract surgery. Good centration, circular overlap in sufficient size and a circular edge without tears result in good centration of the intraocular lens (IOL). In this study, the capsulorhexis results of an experienced surgeon are compared with reported data in femtolaser assisted cataract surgery (FLACS). PATIENTS AND METHODS: 105 consecutive operations were photographically documented; in 81 cases size and overlap were analysed retrospectively...
April 2018: Klinische Monatsblätter Für Augenheilkunde
Sutapa Chandra, Arvind Dhawangale, Soumyo Mukherji
An optimum copper concentration in environment is highly desired for all forms of life. We have developed an ultrasensitive copper sensor which functions from femto to micro molar concentration accurately (R2 = 0.98). The sensor is based on denatured antibody immunoglobulin G (IgG), immobilized on polyaniline (PAni) which in turn is the coating on the core of an optical fiber. The sensing relies on changes in evanescent wave absorbance in the presence of the analyte. The sensor showed excellent selectivity towards Cu (II) ions over all other metal ions...
March 20, 2018: Biosensors & Bioelectronics
Mohammad Miraftab, Hassan Hashemi, Soheila Asgari
Purpose: To compare two-year results of femtosecond laser assisted LASIK (femto-LASIK) and photorefractive keratectomy (PRK) in terms of astigmatism correction in patients with less than 2.0 diopters (D) of spherical error and more than 2.0 D of cylinder error. Methods: In this retrospective study, data were extracted from 100 patient charts. The two study groups were matched by age, gender, and baseline uncorrected distance visual acuity (UDVA) and refractive astigmatism (RA)...
March 2018: Journal of Current Ophthalmology
Cheng-Yu Shih, René Streubel, Johannes Heberle, Alexander Letzel, Maxim V Shugaev, Chengping Wu, Michael Schmidt, Bilal Gökce, Stephan Barcikowski, Leonid V Zhigilei
The synthesis of chemically clean and environmentally friendly nanoparticles through pulsed laser ablation in liquids has shown a number of advantages over conventional chemical synthesis methods and has evolved into a thriving research field attracting laboratory and industrial applications. The fundamental understanding of processes leading to the nanoparticle generation, however, still remains elusive. In particular, the origin of bimodal nanoparticle size distributions in femto- and picosecond laser ablation in liquids, where small nanoparticles (several nanometers) with narrow size distribution are commonly observed to coexist with larger (tens to hundreds of nanometers) ones, has not been explained so far...
April 19, 2018: Nanoscale
J Prieto-Pena, F Gómez, D M González-Castaño, M T Flores-Arias, J Arines, C Bao-Varela, F Cambronero-López, A Martínez Maqueira
This work describes the radiation characterisation and dosimetric measurements performed on the low-energy micromachining station of the femtosecond STELA (Santiago TErawatt LAser) at 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 by 1 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 14, 2018: Physical Chemistry Chemical Physics: PCCP
E Perfetto, D Sangalli, A Marini, G Stefanucci
The early-stage density oscillations of the electronic charge in molecules irradiated by an attosecond XUV pulse takes place on femto- or subfemtosecond time scales. This ultrafast charge migration process is a central topic in attoscience because 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 15, 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...
April 15, 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 1 H 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 28, 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...
March 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...
April 1, 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...
February 1, 2018: Nanoscale
Anna Zieleniewska, Shannon R Harper, Dennis P Arnold, Dirk M Guldi
The focal point of this work is the photophysical characterization of three meso-meso two-atom-bridged diporphyrins. Detailed investigations by means of cyclic voltammetry, absorption, fluorescence, and femto-/nanosecond 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...
February 26, 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
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