The use of specially designed island mask combined with non-laser intensive pulse irradiation produces a lattice of islands of limited thermal damage in SC that substantially enhances the penetration rate of topically applied index-matching agents. The suggested technique gave comparable magnitudes of clearing dynamics enhancement for glucose solution, glycerol solution, and propylene glycol solution applied to mammalian skin.
The optical properties of human stomach wall mucosa were measured in the wavelength range 400-2000 nm. The measurements were carried out using the commercially available spectrophotometer CARY-2415 with an integrating sphere. The combined method based on inverse adding-doubling and inverse Monte Carlo techniques was used to determine the absorption and scattering coefficients and anisotropy factor from the measurements.
Although green femtosecond lasers provide outstanding quality and wide processing windows for monolithic interconnection of the individual cells in organic photovoltaic (OPV) modules, they are hardly used in commercial applications, due to cost reasons.In this work, a process has been developed that allows the monolithic interconnection in OPV modules with an infrared sub-nanosecond laser exclusively, without compromising the performance of the modules. While the photoactive layer is removed easily by green femtosecond pulses without damaging the bottom electrode, this is not possible for infrared nanosecond pulses, due to their much larger optical penetration length, which significantly exceeds the thickness of the active layer and is well absorbed by the indium tin oxide (ITO) layer. This leads to damage of the ITO bottom electrode, which in turn compromises the functionality of the module.By systematically varying single-pulse laser fluence and spatial pulse overlap, the laser parameters are optimized in such a way that the contact area between the residues of the metal oxide bottom electrode and the silver nanowire top electrode is maximized so that the electrical resistances of the contacts are sufficiently small not to affect device performance. This is demonstrated by presenting large-area OPV modules based on the well-characterized reference system P3HT:PCBM that show efficiencies of up to 2.4%. This achievement opens up the way towards reliable roll-to-roll (R2R) laser patterning processes with sub-nanosecond lasers and thus represents a breakthrough with respect to cost-effective R2R manufacturing of OPV modules, due to grossly reduced investment and maintenance costs for laser sources. KEYWORDS flexible organic photovoltaic module, laser patterning, sub-nanosecond pulses 1 | INTRODUCTION Besides flexibility, lightweight, semitransparency, and customized color and shape, the attractiveness of polymer-based organic photovoltaics (OPVs) is based on the possibility of cost-effective deposition of the modules from the liquid phase on large areas by roll-to-roll (R2R) processes. 1 In order to avoid resistive losses and to provide useful voltages, the modules are divided into several cells, which are serially interconnected. The area needed for interconnection is inactive for PV energy generation and is therefore named dead area. The geometrical fill factor (GFF) is defined by the ratio of the PV active area and the total module area and enters directly the calculation of the module efficiency. Traditionally, the interconnection of individual cells is achieved by printing a bottom electrode, the photoactive layer,
In dental health care, the application of ultrashort laser pulses enables dental tissue ablation free from thermal side effects, such as melting and cracking. However, these laser types create undesired micro- and nanoparticles, which might cause a health risk for the patient or surgeon. The aim of this study was to investigate the driving mechanisms of micro- and nanoparticle formation during ultrashort pulse laser ablation of dental tissue. Time-resolved microscopy was chosen to observe the ablation dynamics of mammoth ivory after irradiation with 660 fs laser pulses. The results suggest that nanoparticles might arise in the excited region. The thermal expansion of the excited material induces high pressure in the surrounding bulk tissue, generating a pressure wave. The rarefaction wave behind this pressure wave causes spallation, leading to ejection of microparticles.
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