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High pore density membranes exhibit various applications, especially in microfiltration, bioseparation, microbiology and medicine. The laser ablation process allows the fabrication of membranes with high pore density and pore diameter in the [mu]m and sub-[mu]m range. Ultrashort laser pulses allows the efficient and precise fabrication of pores in polymer foils due to the high repetition rate and the low thermal effects. Polyimide (PI) foils with a thickness of 13 [mu]m were irradiated by ultraviolet picosecond laser radiation. The fabricated membranes have a pore diameter from ~0.7 [mu]m to 75 [mu]m in dependence on the laser parameter. Furthermore, high pore density up to ~23500 mm (-2), high-precision pores with standard deviation of pore diameter less than 10 % and high areal pore density up to ~12 % were achieved. The detailed analysis of the pore size at the front and rear side in correlation to the laser parameter enable an empiric description of the pore size - laser parameter dependency which allows the optimisation of the pore density. Keywords: ps-laser, drilling, membranes, polyimide, PI

Laser-induced plasma etching (LIPE) offers a promising technique for high-quality surface processing under atmospheric pressure. This study investigates the surface modification of polytetrafluoroethylene (PTFE) in air using a high-repetition-rate ultrashort pulsed laser. Key process and laser parameters, including repetition rate, pulse energy, plasma-to-surface distance, and etching time, were analyzed for their impact on etching rates and surface morphology. The etching rate of PTFE under stationary conditions was measured in the picometer-per-pulse range, enabling precise vertical control. Results show that etching rates increase with increasing pulse energy and repetition rate but decrease with greater plasma-to-surface distances. The generated etch grooves are circular and significantly larger than the laser spot size, with etched surfaces exhibiting reduced surface roughness compared to unetched surfaces. Line pattern etching was demonstrated by moving the sample at a constant speed in front of the laser-induced plasma. Unlike laser ablation, LIPE achieves superior vertical depth precision and significantly smoother surface morphology, making it a valuable tool for ultra-precise surface machining applications. Keywords: dry etching, plasma, laser, Polytetrafluoroethylene, surface modification, reactive etching, optical breakdown, laser-induced plasma etching, LIPE

The irradiation of metals with ultrashort laser pulses enables the rapid and cost-effective production of nanostructured surfaces with a wide range of industrial applications. The laser-induced surface roughening modifies the interaction processes upon electron impact, leading to a modification of the secondary electron emission. In this study, the nanostructuring as well as the secondary electron yield (SEY) variation of polycrystalline copper surfaces was investigated by irradiation with 1030 nm infrared ultrashort laser pulses at a constant repetition rate of 100 kHz. The influence of varying the pulse duration between 238 fs and 10 ps, the laser power and the number of laser pulses per unit area (induced by varying the scanning speed) on the surface topography and the SEY was investigated. Irrespective of the pulse duration, irradiation with low scan speed (v [less than or equal to] 20 mm/s) and high laser power (P [greater than or equal to] 2.6 W ) results in the for mation of a surface with compact nanostructures and a very low maximum SEY [[delta].sub.max] < 0.7. The [[delta].sub.max] increased slightly with increasing pulse duration at similar laser parameters. Increasing the pulse duration also resulted in a slight decrease in the ablation threshold and volume. The observed SEY dependence is probably explained by the pulse duration dependence of the ablation. The results suggest that nanostructured copper surfaces with very low SEY can be produced with ultrashort laser pulses over a wide range of pulse durations. Keywords: laser; SEY, copper, nanostructuring, pulse duration

Droplet-induced self-folding processes enable the easy and cost-effective fabrication of millimeter to submillimeter 3D structures from planar templates. These templates were fabricated by laser cutting of polymer foils that offer a high flexibility in design. The interaction of water droplets with template surfaces induces a surface tension force that causes the deformation of the laser-cut templates needed to form the 3D structures. In this study, laser patterning of 25 [micro]m thick polyimide (PI) foils by UV ultrashort pulse laser ablation was used to systematically investigate the effect of hinge geometry on the bending and self-folding process of cubes. The deposition of water droplets on the laser-structured samples leads to forces that move the side faces of the cube template causing a defined deformation of the hinges of the PI template and resulting in a bending angle between hinged template regions. The bending angle was determined as a function of hinge geometry and water droplet volume. The bending angle is increased with increasing droplet volume below a certain maximum but decreased with increasing hinge thickness and width. Finally, 2D laser cut templates with optimized v-shaped hinge structures was sucessful formed into a cube by laser droplet induced self folding. Keywords: ps-laser; laser cutting, self-folding, water droplet, polyimide

The process requirements for ultra-precise machining of surfaces for optical applications is still challenging for laser ablation-based methods. The LIPE (laser-induced plasma etching) method combines the two complementary techniques of laser and plasma processing. Technologically important materials like SiO2, Ge, Si as well fiber-reinforced composites (SiC-SiC) have been successfully processed with LIPE, in particular Polyimide (Kapton@ HN (125 [mu]m)) and Polyethylenterephthalat. In the present paper, LIPE etching of polymer surface is demonstrated. The influence of the main process parameters on the etching rate as well as on the obtained surface characteristics will be shown and discussed in detail. Keywords: laser, optical breakdown, plasma formation, etching, reactive etching, LIPE, polymer, PET, Kapton

The optimum risk score determining perioperative mortality and morbidity in cardiac surgery remains debated. Advanced glycation end products (AGEs) derived from glycaemic and oxidative stress accumulate to a comparable amount in skin and the cardiovascular system leading to a decline in organ function. We aimed to study the association between AGE accumulation measured as skin autofluorescence (sAF) and the outcome of cardiac surgery patients. Between April 2008 and November 2016, data from 758 consecutive patients undergoing coronary artery bypass grafting, aortic valve replacement or a combined procedure were analyzed. Skin autofluorescence was measured using an autofluorescence reader. Beside mortality, for the combined categorical morbidity outcome of each patient failure of the cardiac-, pulmonary-, renal- and cerebral system, as well as reoperation and wound healing disorders were counted. Patients without or with only one of the outcomes were assigned zero points whereas more than one outcome failure resulted in one point. Odds ratios (ORs) were estimated in multivariable logistic regression analysis with other preoperative parameters and the established cardiac surgery risk score systems EuroSCORE II and STS score. Skin autofluorescence as non-invasive marker of tissue glycation provided the best prognostic value in identifying patients with major morbidity risks after cardiac surgery (OR = 3.13; 95%CI 2.16-4.54). With respect to mortality prediction the STS score (OR = 1.24; 95%CI 1.03-1.5) was superior compared to the EuroSCORE II (OR = 1.17: 95%CI 0.96-1.43), but not superior when compared to sAF (OR = 6.04; 95%CI 2.44-14.95). This finding suggests that skin autofluorescence is a good biomarker candidate to assess the perioperative risk of patients in cardiac surgery. Since the EuroSCORE does not contain a morbidity component, in our view further sAF measurement is an option.

Micro-nano patterns are requested for various applications mimicking structures from nature. Here top-down patterning by phase mask irradiation was combined with bottom-up LIPSS (Laser Induced Periodic Surface Structures) formation processes to achieve hierarchically organized structures. Novolac films (200 to 700 nm film thickness) were irradiated by a high number of excimer laser pulses (N = 1500) at very low fluences (F = 12 [+ or -] 1 mJ/[cm.sup.2]) to achieve the LIPSS formation. The area, the organization and the appearance of the LIPSS are related to the confinement of the LIPSS formation area due to the incident laser energy density distribution at the sample. At particular conditions using phase mask irradiation single chain dot like pattern with a size of approximately 220 nm have been achieved. This particular result represents a unique feature of LIPSS formation by surface scattering due to the confinement of the laser-driven interaction processes. DOI: 10.2961/jlmn.2019.02.0002 Keywords: laser, excimer laser, novolac, polymer, micro pattern, nano pattern, LIPSS

Background The TransEurope FootRace 2009 (TEFR09) was one of the longest transcontinental ultramarathons with an extreme endurance physical load of running nearly 4,500 km in 64 days. The aim of this study was to assess the wide spectrum of adaptive responses in humans regarding the different tissues, organs and functional systems being exposed to such chronic physical endurance load with limited time for regeneration and resulting negative energy balance. A detailed description of the TEFR project and its implemented measuring methods in relation to the hypotheses are presented. Methods The most important research tool was a 1.5 Tesla magnetic resonance imaging (MRI) scanner mounted on a mobile unit following the ultra runners from stage to stage each day. Forty-four study volunteers (67% of the participants) were cluster randomized into two groups for MRI measurements (22 subjects each) according to the project protocol with its different research modules: musculoskeletal system, brain and pain perception, cardiovascular system, body composition, and oxidative stress and inflammation. Complementary to the diverse daily mobile MR-measurements on different topics (muscle and joint MRI, T2*-mapping of cartilage, MR-spectroscopy of muscles, functional MRI of the brain, cardiac and vascular cine MRI, whole body MRI) other methods were also used: ice-water pain test, psychometric questionnaires, bioelectrical impedance analysis (BIA), skinfold thickness and limb circumference measurements, daily urine samples, periodic blood samples and electrocardiograms (ECG). Results Thirty volunteers (68%) reached the finish line at North Cape. The mean total race speed was 8.35 km/hour. Finishers invested 552 hours in total. The completion rate for planned MRI investigations was more than 95%: 741 MR-examinations with 2,637 MRI sequences (more than 200,000 picture data), 5,720 urine samples, 244 blood samples, 205 ECG, 1,018 BIA, 539 anthropological measurements and 150 psychological questionnaires. Conclusions This study demonstrates the feasibility of conducting a trial based centrally on mobile MR-measurements which were performed during ten weeks while crossing an entire continent. This article is the reference for contemporary result reports on the different scientific topics of the TEFR project, which may reveal additional new knowledge on the physiological and pathological processes of the functional systems on the organ, cellular and sub-cellular level at the limits of stress and strain of the human body. Please see related articles: http://www.biomedcentral.com/1741-7015/10/76 and http://www.biomedcentral.com/1741-7015/10/77

The structuring of thermal-sensitive functional layers by laser patterning methods remains a challenge. The shock-wave-induced thin-film delamination (SWIFD) process is a non-thermal process of mechanically-induced film removal where the process exhibits an extraordinary application potential. Due to the spatial separation of laser ablation that is performed at the rear side of the substrate and the shock-wave-induced thin film delamination at the substrate's film side the thermal impact to the thin films is excluded. The SWIFD process for CIGS solar cells on polyimide substrates was studied for dependence on externally applied tension forces F. The resulting SWIFD patterns are imaged by scanning electron microscopy (SEM) to analyze the geometrical shape and the surface morphology. A reduction of the CIGS delamination threshold fluence Ф· as well as a slight increase of the delaminated area A with increasing tension forces F is found. Like previous results, the area A increases with growing laser fluence and number of laser pulses and the Ф· decreases with increasing number of laser pulses. The non-thermal nature of the SWIFD process, enabling a film-selective delamination of the CIGS layer (including the front contact) without damaging the Mo back contact, is also shown.

This study examines the social forces that drive deforestation. Neo-Malthusian, modernization, and dependency theories are applied in a cross-national comparison of 51 developing countries. Multiple regression techniques are applied to estimate the rate of deforestation using the level of urbanization, economic growth rate, population growth rate, level of sectoral inequality, rate of change in primary product exports, and rate of change in tertiary education. Results support modernization theory, indicating that the level of urbanization has a curvilinear effect on the rate of deforestation, that economic growth contributes to deforestation, and that sectoral inequality reduces the rate of deforestation. In support of neo-Malthusian theory, population growth results in higher rates of deforestation. Tertiary education has a mild negative effect on the rate of deforestation, whereas the effect of trade dependency is insignificant.