Approaching soft X-ray wavelengths in nanomagnet-based microwave technology.

Seven decades after the discovery of collective spin excitations in microwave-irradiated ferromagnets, there has been a rebirth of magnonics. However, magnetic nanodevices will enable smart GHz-to-THz devices at low power consumption only, if such spin waves (magnons) are generated and manipulated on the sub-100 nm scale. Here we show how magnons with a wavelength of a few 10 nm are exploited by combining the functionality of insulating yttrium iron garnet and nanodisks from different ferromagnets. We demonstrate magnonic devices at wavelengths of 88 nm written/read by conventional coplanar waveguides. Our microwave-to-magnon transducers are reconfigurable and thereby provide additional functionalities. The results pave the way for a multi-functional GHz technology with unprecedented miniaturization exploiting nanoscale wavelengths that are otherwise relevant for soft X-rays. Nanomagnonics integrated with broadband microwave circuitry offer applications that are wide ranging, from nanoscale microwave components to nonlinear data processing, image reconstruction and wave-based logic.

Magnetic thin-film insulator with ultra-low spin wave damping for coherent nanomagnonics.

Wave control in the solid state has opened new avenues in modern information technology. Surface-acoustic-wave-based devices are found as mass market products in 100 millions of cellular phones. Spin waves (magnons) would offer a boost in today's data handling and security implementations, i.e., image processing and speech recognition. However, nanomagnonic devices realized so far suffer from the relatively short damping length in the metallic ferromagnets amounting to a few 10 micrometers typically. Here we demonstrate that nm-thick YIG films overcome the damping chasm. Using a conventional coplanar waveguide we excite a large series of short-wavelength spin waves (SWs). From the data we estimate a macroscopic of damping length of about 600 micrometers. The intrinsic damping parameter suggests even a record value about 1 mm allowing for magnonics-based nanotechnology with ultra-low damping. In addition, SWs at large wave vector are found to exhibit the non-reciprocal properties relevant for new concepts in nanoscale SW-based logics. We expect our results to provide the basis for coherent data processing with SWs at GHz rates and in large arrays of cellular magnetic arrays, thereby boosting the envisioned image processing and speech recognition.

Omnidirectional spin-wave nanograting coupler.

Magnonics as an emerging nanotechnology offers functionalities beyond current semiconductor technology. Spin waves used in cellular nonlinear networks are expected to speed up technologically, demanding tasks such as image processing and speech recognition at low power consumption. However, efficient coupling to microelectronics poses a vital challenge. Previously developed techniques for spin-wave excitation (for example, by using parametric pumping in a cavity) may not allow for the relevant downscaling or provide only individual point-like sources. Here we demonstrate that a grating coupler of periodically nanostructured magnets provokes multidirectional emission of short-wavelength spin waves with giantly enhanced amplitude compared with a bare microwave antenna. Exploring the dependence on ferromagnetic materials, lattice constants and the applied magnetic field, we find the magnonic grating coupler to be more versatile compared with gratings in photonics and plasmonics. Our results allow one to convert, in particular, straight microwave antennas into omnidirectional emitters for short-wavelength spin waves, which are key to cellular nonlinear networks and integrated magnonics.

Directed acceleration of electrons from a solid surface by Sub-10-fs laser pulses.

Electrons have been accelerated from solid target surfaces by sub-10-fs laser pulses of 120 microJ energy which were focused to an intensity of 2x10;{16} W/cm;{2}. The electrons have a narrow angular distribution, and their observed energies exceed 150 keV. We show that these energies are not to be attributed to collective plasma effects but are mainly gained directly via repeated acceleration in the transient field pattern created by incident and reflected laser, alternating with phase-shift-generating scattering events in the solid.

Novel method for characterizing relativistic electron beams in a harsh laser-plasma environment.

Particle pulses generated by laser-plasma interaction are characterized by ultrashort duration, high particle density, and sometimes a very strong accompanying electromagnetic pulse (EMP). Therefore, beam diagnostics different from those known from classical particle accelerators such as synchrotrons or linacs are required. Easy to use single-shot techniques are favored, which must be insensitive towards the EMP and associated stray light of all frequencies, taking into account the comparably low repetition rates and which, at the same time, allow for usage in very space-limited environments. Various measurement techniques are discussed here, and a space-saving method to determine several important properties of laser-generated electron bunches simultaneously is presented. The method is based on experimental results of electron-sensitive imaging plate stacks and combines these with Monte Carlo-type ray-tracing calculations, yielding a comprehensive picture of the properties of particle beams. The total charge, the energy spectrum, and the divergence can be derived simultaneously for a single bunch.

Production of dense plasmas with sub-10-fs laser pulses.

Close to solid state density plasmas with peak electron temperatures of about 190 eV have been generated with sub-10-fs laser pulses incident on solid targets. Extreme ultraviolet (XUV) spectroscopy is used to investigate the K shell emission from the plasma. In the spectra, a series limit for the H- and He-like resonance lines becomes evident which is explained by pressure ionization in the dense plasma. The spectra are consistent with computer simulations calculating the XUV emission and the expansion of the plasma.

Development and validation of analytical methods for monomeric and oligomeric migrants from nylon 12 packaging materials.

Analytical methods for the determination of laurolactam--the monomer of nylon 12--as well as the cyclic dimer and trimer were established. High performance liquid chromatography using ultraviolet (HPLC-UV) and mass spectrometric detection (HPLC-MS) were both found suitable to identify and quantify monomer, cyclic dimer and trimer well below the specific migration limit (SML) of laurolactam, being 5 mg/kg of food (simulant). Gas chromatography with flame ionisation detection (GC-FID) showed to be an appropriate method for the detection of only laurolactam in aqueous and fatty food simulants. Food simulants could be analysed directly by all three methods, or after a change of solvents. For olive oil, a method for sample clean-up by size-exclusion chromatography (SEC) was established.

Chemistry and biology of thiamethoxam: a second generation neonicotinoid.

Thiamethoxam is the first commercial neonicotinoid insecticide from the thianicotinyl subclass. It was discovered in the course of our optimisation program on neonicotinoids started in 1985. Novel variations of the nitroimino-heterocycle of imidacloprid led to 4-nitroimino-1,3,5-oxadiazinanes exhibiting high insecticidal activity. Among these, thiamethoxam (CGA 293433) was identified as the best compound and selected for worldwide development. The compound can be synthesised in only a few steps and high yield from easily accessible starting materials. Thiamethoxam acts by binding to nicotinic acetylcholine receptors. It exhibits exceptional systemic characteristics and provides excellent control of a broad range of commercially important pests, such as aphids, jassids, whiteflies, thrips, rice hoppers, Colorado potato beetle, flea beetles and wireworms, as well as some lepidopteran species. In addition, a strong preventative effect on some virus transmissions has been demonstrated. Thiamethoxam is developed both for foliar/soil applications and as a seed treatment for use in most agricultural crops all over the world. Low use rates, flexible application methods, excellent efficacy, long-lasting residual activity and favourable safety profile make this new insecticide well-suited for modern integrated pest management programmes in many cropping systems.

Chiroptical detection during liquid chromatography 7. The rotation angle/absorbance ratio of chiral molecules. Its possible use for on-line analysis during preparative separations of enantiomers.

The rotation angle/absorbance ratios C+ = alpha+/A+ and C- = a-/A-, determined via detection by a polarimeter and a photometer, were checked for the first time with reference to their use for on-line analysis during preparative separations. For this purpose, (+)-, (-)- and (+/-)-carvones were investigated by liquid chromatography (LC) on microcrystalline tribenzoylcellulose. It turned out that the ratios C+ and C- depend only slightly upon concentration (Table 1). Overlapped peaks of enantiomers were successfully submitted to computer deconvolution (e.g. Fig. 2, bottom). A procedure for on-line analysis during preparative LC is proposed.

Continuous intra-arterial oximetry, pulse oximetry, and co-oximetry during cardiac surgery.

This study evaluated arterial catheter oximetry versus pulse oximetry in eight patients (ASA III-IV) who underwent cardiac surgery. Co-oximeter saturation values served as the standard. Arterial oxygen saturation was determined simultaneously with these three methods at 162 prospectively defined points of measurement before, during, and after cardiopulmonary bypass (CPB). At the same times before and after CPB, arterial, pulmonary arterial, and central venous pressures, and cardiac output determinations were recorded. Saturation readings were obtained in more than 99% of measurements with catheter oximetry and in only 59% to 84% of measurements with pulse oximetry. Failure of pulse oximetry correlated with low mean arterial pressures and low cardiac outputs, but not with high systemic vascular resistance. The mean saturation values determined by catheter oximetry as well as by pulse oximetry differed from the mean values obtained by co-oximetry by less than 1% (= bias). The standard deviations of the individual differences between readings of catheter or pulse oximetry and readings of co-oximetry (= precision) were +/- 0.5% to +/- 1.0% for catheter oximetry and +/- 1.0% to +/- 1.2% for pulse oximetry. In summary, catheter oximetry was superior to pulse oximetry with regard to obtaining readings and to reliability of the obtained readings. Invasiveness and high costs influence the decision as to whether to use catheter oximetry, but if reliable and precise measurements of saturation are important at any time during surgery, pulse oximetry is an insufficient method and co-oximetry is a time-consuming method of analysis, whereas catheter oximetry is quick, reliable, and precise.

[Intra-arterial catheter oximetry and pulse oximetry in comparison with CO-oximetry in heart surgery]. / Intraarterielle Katheteroxymetrie und Pulsoxymetrie im Vergleich zur CO-Oxymetrie bei herzchirurgischen Eingriffen.

This study evaluates the measurement of oxygen saturation by arterial catheter oximetry and pulse oximetry. The values are compared to values obtained by CO-oximetry. METHODS. In eight patients undergoing cardiac surgery, we determined the oxygen saturation of arterial and mixed-venous blood by CO-oximetry (IL 282, Instrumentation Lab) at prospectively defined points of measurement before, during, and after extracorporeal circulation. At the same points of measurement, saturation readings obtained by arterial catheter oximetry (U425C, Abbott) and pulse oximetry (Siemens/Nellcor) were recorded. RESULTS. The mean saturation values determined by both catheter oximetry and pulse oximetry differed from the mean values obtained by CO-oximetry by less than 1% (= bias). The standard deviations of the readings in relation to readings of CO-oximetry (= precision) were +/- 0.5% to +/- 1.0% for catheter oximetry and +/- 1.0% to +/- 1.3% for pulse oximetry. Furthermore, it was possible to obtain saturation readings in 99%-100% of measurements by catheter oximetry; in contrast, this was possible by pulse oximetry in only 59%-84% of measurements. Low mixed-venous saturation values were not indicated by any of the arterial methods of measurement. CONCLUSIONS. Catheter oximetry was superior to pulse oximetry with regard to both precision of saturation values and reliability to obtain values. Invasiveness and high costs are disadvantages of catheter oximetry, but if reliable and exact measurements are important at any time during surgery or intensive therapy, intra-arterial catheter oximetry is preferable to pulse oximetry.

[The combination of general anesthesia and interscalene block in shoulder surgery]. / Die Kombination von Allgemeinanaesthesie und Interskalenusblockade bei Operationen an der Schulter.

Surgery on the shoulder often causes severe pain and, therefore, requires high doses of opiates. As postoperative pain is frequently treated inadequately, it is desirable to seek alternatives for providing effective analgesia. In a prospective study we examined the efficacy of balanced anesthesia consisting of general anesthesia combined with interscalene brachial plexus blockade for intra- and postoperative analgesia for operations on the shoulder. METHODS. Using the technique described by Winnie, interscalene block (ISB) was performed in 100 awake patients. After location of the brachial plexus by means of a peripheral nerve stimulator, we injected 40 ml bupivacaine 0.375%, after which general anesthesia (GA) was induced. At three predetermined points in time (recovery room, 8 h, and 24 h after the end of surgery), pain was evaluated by a visual analogue scale ranging from 0 to 10 and the extent of sensory blockade was tested by the pinprick method. The results of the pain scores and individual demands for analgesics were compared with a group of 22 patients who received only GA. Both groups were comparable in age, sex, and type of surgical procedure. RESULTS. We noted technical failure of the ISB in 8% of our patients. Side effects such as Horner's syndrome (18%), phrenic nerve paralysis (10%), and recurrent laryngeal nerve block (1%) were only temporarily observed during the action of the local anesthetics. During the surgical procedure, the group with ISB received a mean dose of 0.13 +/- 0.07 mg fentanyl versus 0.29 +/- 0.08 mg in the GA group (P less than 0.01) with equipotent doses of volatile anesthetics (1.0 to 1.5 MAC enflurane). Postoperative pain occurred for the first time in 39% of the patients given ISB later than 12 h after the end of surgery (average 8.7 +/- 5.9 h). In contrast, 95% of the patients with GA complained of pain in the recovery room. Pain measurement by the analogue scale clearly demonstrated the advantages of balanced anesthesia directly and 8 h after the operation (P less than 0.01). Even 24 h after the end of the surgical procedure the patients had better pain relief (P less than 0.05) in spite of the decreasing effect of the ISB. These significant differences led to the following results for postoperative treatment: 35% of the patients with ISB did not require additional analgesics during the first 24-h period after surgery, whereas 95% of those with GA requested analgesia. Only 32% of the ISB patients required opioids versus 86% with GA. The average duration of stay in the recovery room was reduced by 25% in the group with ISB (86 vs 134 min). In a final assessment, 84% of the patients were satisfied with the balanced anesthesia and only 5% were disappointed with the method. CONCLUSION. The combination of ISB and GA allows a reduction in intraoperative doses of opiates and facilitates postoperative pain management. Because of the low incidence of side effects, the lack of complications, and the high degree of patient acceptance, we recommend this type of balanced anesthesia for patients undergoing shoulder surgery.

Costs of different methods to control riverine tsetse in West Africa.

Tsetse projects in several West African countries using different techniques to control or eradicate the fly were analysed in order to obtain comparable figures on the economics of the respective strategies. In the first stage the study concentrated on the control of riverine species by trapping, aerial spraying and sterile male release. First results with regard to the costs of the different methods are presented.