THz Properties of Adhesives

We determined the THz properties of 12 different adhesives which are mainly used for industrial purposes. The adhesives applied can be classified according to their chemical structure: epoxy resins, acrylic resins, and polyurethane based materials. This work represents a basis for future studies, which will concentrate on aging effects, including the absorption of water of adhesive joints. Thus, the dielectric properties of the unaged adhesives are investigated and the results of these measurements are described herein.     

Monolithic Mode-Locked Laser and Optical Amplifier for Regenerative Pulsed Optical Clock Recovery

We experimentally demonstrate optical clock recovery using a novel mode-locked laser (MLL) monolithically integrated with an output semiconductor optical amplifier. The laser's mirror placement is determined using lithography, allowing for mode locking and clock recovery at the exact frequency of the design (35.00 GHz), which is easily scalable to 40 GHz or higher. The design is compatible with other photonic integrated circuit components, enabling integrated signal processing with MLLs. The device generates pulses at 35.0-GHz repetition rate with 6-ps pulsewidth, over 12-dB extinction ratio (ER), and 8.3-dBm output power. Among other regenerative capabilities, the device performs optical clock recovery with 50% jitter reduction from a degraded input signal with low ER     

Measurements of endotoxin on ambient loaded PM filters after long-term storage

At present there exist unsolved questions, whether endotoxin measurements on PM filters show valid measurements after long-term storage of loaded PM filters. As part of the TRAPCA study we collected particles with a 50% aerodynamic cut-off diameter of 2.5 microm (PM(2.5)) at 40 outdoor sites and particles less than 10 microm in size (PM(10)) at a subset of these sites (N=12) in Munich. The PM filters were cut in halves and endotoxin was measured in the extract of one filter half 2-3 years after PM collection. Here we present the results of repeated endotoxin measurements, where the association between previously measured endotoxin concentrations, measurements from stored eluates, and measurements in extracts of the second filter halves were determined. No statistically significant changes were seen between our old measurements and those from the stored eluates. Additionally, no change was observed between previously measured endotoxin concentrations and those from the stored set of filter halves. We found an average increase of 5% between our old measurements and those from the stored eluates and of 19% between the old measurements and those from the stored set of filter halves. The correlations between the previously measured endotoxin concentrations and the repeated measurements from the stored eluates were high (r=0.789) for EU/m(3) PM(2.5). Since endotoxin was evaluated from the same set of filter halves, it is obvious that storage over three years did not substantially effect the correlation of the endotoxin content. Regarding the outliers from previous measurements unsymmetric endotoxin spots on one out of 48 filter halves could be determined. Apart from this we conclude that the endotoxin is homogenously distributed on the filter halves and that endotoxin levels, which were repeatedly measured from filters stored over three years, could be determined validly.     

Anwendung des Neutralisationspotenzials bei der Bilanzierung von Säure-Base-Reaktionen im Umfeld des Braunkohlebergbaues

Acidic conditions of seepage and groundwater originating from open pit minings in Lusatia are described using the neutralization potential, which is based on the concept of acidity. Acid formation and buffer reactions can be reduced to three elemental reactions: oxidation of pyrit/reduction of sulfate, dissolution of carbonate and gypsum equilibrium. These reactions are combined in a genetic model in order to interpret the origin of mineral and acid contents of different groundwaters influenced by lignite mining. The statistical results of these calculations are summarised in order to calibrate parameters of a prognostic model. The method described here is used to prepare restoration measures.     

Picosecond gain dynamics of an actively mode-locked external-cavitylaser diode

We report a new experimental approach to study the temporal gain dynamics of an actively mode-locked external-cavity laser diode. The experiment can be viewed as an electrical pump-optical probe technique. Picosecond time resolution is achieved by synchronizing the actively mode-locked semiconductor laser to a mode-locked Ti:sapphire laser. The transmission of the Ti:sapphire pulses through the active region of the laser diode is then measured as a function of photon energy and delay time. Our experiment allows to investigate the dynamics of the entire gain spectrum with picosecond time resolution since the Ti:sapphire laser is wavelength tunable. On the basis of these data we are able to determine directly the wavelength dependence of the differential gain. The results compare well with microscopic calculations. The implication for the mode-locking behavior of the diode laser is discussed     

GaInAs/GaInAsP multiple-quantum-well integrated heterodyne receiver

Describes the fabrication and performance of the first integrated heterodyne receiver capable of actual heterodyne data reception. Integrating a continuously tunable 1.5 mu m MQW-DBR laser with a single-mode directional coupler/switch and zero-bias MQW waveguide photodetectors, the authors have achieved error-free reception of FSK-modulated pseudorandom digital code at 105 Mbit/s.<>     

Microvasculatory reaction of skeletal muscle to Ti–15Mo in comparison to well-established titanium alloys

Beta-titanium alloys such as Ti–15Mo are increasingly utilized for orthopaedic implant applications because of their excellent corrosion resistance and low elastic modulus. Particularly in osteosynthesis, where the biomaterial stands in direct contact to soft tissue, undesirable biologic reactions may have severe consequences especially in the vulnerable state of trauma and added iatrogenic damage to the microvascular system. In a comparative study we therefore assessed in vivo nutritive perfusion and leukocytic response of striated muscle to the biomaterials Ti–15Mo, Ti–6Al–4V and Ti–6Al–7Nb, thereby drawing conclusions on their short term inflammatory potential. Utilizing the well established skinfold chamber preparation in the hamster and intravital fluorescence microscopy, we could not demonstrate any significant discrepancies between the three alloys. All metals induced an initial moderate inflammatory response in skeletal muscle microcirculation. While recuperation of animals treated with Ti–15Mo and Ti–6Al–7Nb was prompt, we documented a slightly more sluggish recovery of Ti–6Al–4V treated animals. A gross toxicity was not observed for any of the alloys. Conclusively, Ti–15Mo, Ti–6Al–4V and Ti–6Al–7Nb induce an only transient inflammatory answer of the striated muscle microvascular system. Our results indicate that on the microvascular level the tested bulk Ti-alloys do not cause enduring biologic impairment in muscle. No benefit of any kind has or will be received either directly or indirectly by the authors.     

Determination of the acoustic output of a harmonic scalpel

The acoustic output of a harmonic scalpel was experimentally determined, and both the airborne ultrasound and the ultrasound transmitted in water were taken into account. The sound pressure level of airborne ultrasound was measured with a microphone and an artificial head, so that the free-field value and the sound level at the entrance at the bottom of the cavum conchae of the ear could be determined. The derived output power in water was obtained from a hydrophone measurement. The results were strongly influenced by cavitation effects, and it is shown that the power values with and without cavitation differ by more than a factor of 5. The measurement of acoustic output parameters forms the basis for describing the performance of the devices and for an assessment of the risk of harmful bioeffects on both the operator and the patient.     

Dermal uptake of nicotine from air and clothing: Experimental verification

This study aims to elucidate in greater detail the dermal uptake of nicotine from air or from nicotine‐exposed clothes, which was demonstrated recently in a preliminary study. Six non‐smoking participants were exposed to gaseous nicotine (between 236 and 304 μg/m³) over 5 hours while breathing clean air through a hood. Four of the participants wore only shorts and 2 wore a set of clean clothes. One week later, 2 of the bare‐skinned participants were again exposed in the chamber, but they showered immediately after exposure instead of the following morning. The 2 participants who wore clean clothes on week 1 were now exposed wearing a set of clothes that had been exposed to nicotine. All urine was collected for 84 hours after exposure and analyzed for nicotine and its metabolites, cotinine and 3OH‐cotinine. All participants except those wearing fresh clothes excreted substantial amounts of biomarkers, comparable to levels expected from inhalation intake. Uptake for 1 participant wearing exposed clothes exceeded estimated intake via inhalation by >50%. Biomarker excretion continued during the entire urine collection period, indicating that nicotine accumulates in the skin and is released over several days. Absorbed nicotine was significantly lower after showering in 1 subject but not the other. Differences in the normalized uptakes and in the excretion patterns were observed among the participants. The observed cotinine half‐lives suggest that non‐smokers exposed to airborne nicotine may receive a substantial fraction through the dermal pathway. Washing skin and clothes exposed to nicotine may meaningfully decrease exposure.