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The nitrogen-vacancy (N-V) center in diamond has been established as a prime building block for quantum networks. However, scaling beyond a few network nodes is currently limited by low spin-photon entanglement rates, resulting from the N-V center's low probability of coherent photon emission and collection. Integration into a cavity can boost both values via the Purcell effect, but poor optical coherence of near-surface N-V centers has so far prevented their resonant optical control, as would be required for entanglement generation. Here, we overcome this challenge, and demonstrate resonant addressing of individual, fiber-cavity-coupled N-V centers, and collection of their Purcell-enhanced coherent photon emission. Utilizing off-resonant and resonant addressing protocols, we extract an enhancement of the zero-phonon line emission by a factor of up to 4, consistent with a detailed theoretical model. This model predicts that the probability of coherent photon detection per optical excitation can be increased to 10% for realistic parameters - an improvement over state-of-the art solid immersion lens collection systems by 2 orders of magnitude. The resonant operation of an improved optical interface for single coherent quantum emitters in a closed-cycle cryogenic system at T∼4 K is an important result towards extensive quantum networks with long coherence.

The advancement of quantum optical science and technology with solid-state emitters such as nitrogen-vacancy (NV) centers in diamond critically relies on the coherence of the emitters' optical transitions. A widely employed strategy to create NV centers at precisely controlled locations is nitrogen ion implantation followed by a high-temperature annealing process. We report on experimental data directly correlating the NV center optical coherence to the origin of the nitrogen atom. These studies reveal low-strain, narrow-optical-linewidth ($1$ GHz) and higher strain. The data show that the poor optical coherence of the NV centers formed from implanted nitrogen is not due to an intrinsic effect related to the diamond or isotope. These results have immediate implications for the positioning accuracy of current NV center creation protocols and point to the need to further investigate the influence of lattice damage on the coherence of NV centers from implanted ions.

We report on the realization and application of nondestructive three-qubit parity measurements on nuclear spin qubits in diamond. We use high-fidelity quantum logic to map the parity of the joint state of three nuclear spin qubits onto an electronic spin qubit that acts as an ancilla, followed by a single-shot nondestructive readout of the ancilla combined with an electron spin echo to ensure outcome-independent evolution of the nuclear spins. Through the sequential application of three such parity measurements, we demonstrate the generation of genuine multipartite entangled states out of the maximally mixed state. Furthermore, we implement a single-shot version of the Greenberger-Horne-Zeilinger experiment that can generate a quantum versus classical contradiction in each run. Finally, we test a state-independent noncontextuality inequality in eight dimensions. The techniques and insights developed are relevant for fundamental tests as well as for quantum information protocols such as quantum error correction.

In the implementation of device-independent quantum key distribution we are interested in maximizing the key rate, i.e. the number of key bits that can be obtained per signal, for a fixed security parameter. In the finite size regime, we furthermore also care about the minimum number of signals required before key can be obtained at all. Here, we perform a fully finite size analysis of device independent protocols using the CHSH inequality both for collective and coherent attacks. For coherent attacks, we sharpen the results recently derived in Arnon-Friedman et al., Nat. Commun. 9, 459 (2018), to reduce the minimum number of signals before key can be obtained. In the regime of collective attacks, where the devices are restricted to have no memory, we employ two different techniques that exploit this restriction to further reduce the number of signals. We then discuss experimental platforms in which DIQKD may be implemented. We analyse Bell violations and expected QBER achieved in previous Bell tests with distant setups and situate these parameters in the security analysis. Moreover, focusing on one of the experimental platforms, namely nitrogen-vacancy based systems, we describe experimental improvements that can lead to a device-independent quantum key distribution implementation in the near future., Comment: 39+15 pages, 7 figures. Minor improvements in the main text; references added. Revised proofs of Theorems 2 and 3, correcting dependence on the conditioned state. Close to the published version

Boundary layer conditions in polar regions have been shown to have a significant impact on the levels of trace gases in the lower atmosphere. The ability to properly describe boundary layer characteristics (e.g., stability, depth, and variations on diurnal and seasonal scales) is essential to understanding the processes that control chemical budgets and surface fluxes in these regions. Surface turbulence data measured from 3D sonic anemometers on an 8-m tower at Summit Station, Greenland, were used for estimating boundary layer depths (BLD) in stable to weakly stable conditions. The turbulence-derived BLD estimates were evaluated for June 2010 using direct BLD measurements from an acoustic sounder located approximately 50 m away from the tower. BLDs during this period varied diurnally; minimum values were less than 10 m, and maximum values were greater than 150 m. BLD estimates provided a better comparison with sodar observations during stable conditions. Ozone and nitrogen oxides were also measured at the meteorological tower and investigated for their dependency on boundary layer structure. These analyses, in contrast to observations from South Pole, Antarctica, did not show a clear relation between surface-layer atmospheric trace-gas levels and the stable boundary layer.

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Aim: The aim of the study was to simultaneously test the EASI lead system and two other derived ECG methods against the standard 12-lead ECG during percutaneous coronary intervention (PCI). Methods: During 44 percutaneous coronary interventions, a simultaneously recorded 12-lead and EASI ECG were marked at the start of the PCI (baseline) and at known ischemia caused by balloon inflation (peak). ST deviations were measured 60 ms after the J point at baseline and peak in all leads and were summated (SUMST) to assess overall changes. For regional changes, the lead with the highest ST deviation (PEAKST) was marked. For each patient, derived 12-lead ECGs were computed from the EASI leads and a lead subset using patient-specific coefficients (PS) and coefficients based on a patient population (GEN). Absolute differences were computed between each derived and routine ECG for SUMST and PEAKST. Results: SUMST was at baseline 567 mu V (range: 150-1707) and increased at peak to 871 mu V (range: 350-2101). SUMST difference at peak was for EASI: 163 mu V (CI: 90-236, P

This article presents a numerical model that was developed for the drying of ink-jet-printed polymer solutions after filling the pixels in a polymer LED display. The model extends earlier work presented in the literature while still maintaining a practical approach in limiting the number of input parameters needed. Despite some rigorous assumptions, the model is in fair agreement with experimental data from a pre-pilot ink-jet printing line. Comparison inside a single pixel is shown, as well as a general trend in which the amount of polymer that is transported out of the central part of the pixel decreases with the rate of viscosity increase as a function of polymer concentration. Moreover, the effect of a varying solute diffusion coefficient is studied.

This paper reports on an experimental study of the impact of water droplets on a solid substrate, with a droplet radius between 18 and 42 μm. We optically measured the interface shape during impact. The measured impact sequences show the impact phenomenology, droplet radius as a function of time, and oscillation behavior in the later stages of impact. The measured radius during impact is compared with existing models, and some of the deficiencies of common models are shown. The measured oscillation frequency in the later stage of impact compares well with an available analytical model. In addition, we measured the volume of the small bubble, which forms in the initial impact stage, as a function of impact velocity. The measured volume compares reasonably well with an approximate model based on air entrapment.

Twelve-lead ST-segment monitoring is a widely used tool for capturing focal ischemia and transient intermittent episodes. However, continuous registration of all 10 electrodes is impractical in clinical settings. This study investigated the accuracy of 2 derived 12-lead strategies that required 6 electrodes, including all limb leads, and 2 precordial leads by using population-based (generalized) and individualized (patient-specific) reconstruction coefficients to derive the additional 4 chest leads. A total of 26,880 simultaneous digital conventional 12-lead generalized and patient-specific electrocardiograms were monitored over 112 hours in 39 patients during percutaneous coronary intervention, including 159 balloon occlusions in 63 arteries, to test accuracy at rest and during ischemia. Occlusion duration was 78 seconds (range 42 to 96) in the left main coronary in 2 patients, the left anterior descending artery in 15, the right coronary artery in 10, the circumflex artery in 2, and graft segments in 5 patients. Average summated 12-lead ST deviation over the study population at baseline was 377 microV (range 104 to 1,718), which increased at peak ischemia to an average of 1,086 microV (range 282 to 4,099). Median absolute differences at peak ischemic ST deviation were 25 microV in lead V(1), 0 microV in lead V(2), 35 microV in lead V(3), 34 microV in lead V(4), 0 microV in lead V(5), 11 microV in lead V(6), and 114 microV for summated 12-lead ST deviation with the generalized method and 7 microV in lead V(1), 4 microV in lead V(2), 1 muV in lead V(3), 5 microV in lead V(4), 4 microV in lead V(5), 9 microV in lead V(6), and 83 microV for the summated 12-lead ST deviation with the patient-specific method. Limb leads (I, II, III, aVR, aVL, and aVF) were identical in all patients. Thus, generalized and patient-specific methods derived from 12-lead electrocardiography using actual limb and 2 precordial electrodes accurately derived the additional chest leads at rest and during ischemia. These approaches appear to be more practical than conventional 10-electrode monitoring but preserve high accuracy.

Three high redshift radio galaxies, 1345+245 (4C 24.28, $z=2.889$), 1809+407 (4C 40.36, $z=2.267$) and 2349+289 (4C 28.58, $z=2.905$) were observed with VLBI at 327 MHz giving an angular resolution of $\simeq$40–100 mas and yielding images with the off-source noise level of 3$\sigma \simeq 3.5$ mJy/beam. On the centiarcsecond scale, the three sources are each characterized by two components with asymmetry both in flux density and in size. The compact components in the VLBI maps correspond to the hot spots in the VLA maps. No radio cores have been detected. The physical parameters for the components derived are consistent with a model in which shocks accelerate electrons in the hotspots.

Quantum networks distributed over distances greater than a few kilometres will be limited by the time required for information to propagate between nodes. We analyse protocols that are able to circumvent this bottleneck by employing multi-qubit nodes and multiplexing. For each protocol, we investigate the key network parameters that determine its performance. We model achievable entangling rates based on the anticipated near-term performance of nitrogen-vacancy centres and other promising network platforms. This analysis allows us to compare the potential of the proposed multiplexed protocols in different regimes. Moreover, by identifying the gains that may be achieved byimproving particular network parameters, our analysis suggests the most promising avenues for research and development of prototype quantum networks.

We report on the fabrication and characterization of a Fabry-Perot microcavity enclosing a thin diamond membrane at cryogenic temperatures. The cavity is designed to enhance resonant emission of single nitrogen-vacancy centers by allowing spectral and spatial tuning while preserving the optical properties observed in bulk diamond. We demonstrate cavity finesse at cryogenic temperatures within the range of F=4000–12 000 and find a sub-nanometer cavity stability. Modeling shows that coupling nitrogen-vacancy centers to these cavities could lead to an increase in remote entanglement success rates by three orders of magnitude., Applied Physics Letters, 110 (17), ISSN:0003-6951, ISSN:1077-3118

Realizing robust quantum information transfer between long-lived qubit registers is a key challenge for quantum information science and technology. Here we demonstrate unconditional teleportation of arbitrary quantum states between diamond spin qubits separated by 3 meters. We prepare the teleporter through photon-mediated heralded entanglement between two distant electron spins and subsequently encode the source qubit in a single nuclear spin. By realizing a fully deterministic Bell-state measurement combined with real-time feed-forward, quantum teleportation is achieved upon each attempt with an average state fidelity exceeding the classical limit. These results establish diamond spin qubits as a prime candidate for the realization of quantum networks for quantum communication and network-based quantum computing.

In an attempt to decolonise the patient from the ESBL producing E. coli, he underwent donor feces infusion in May 2013. Prior to this intervention, the presence of ESBL producing E. coli in the large intestine was again confirmed by a positive rectal culture. In addition his throat and perineum were also screened for the presence of ESBL producing Enterobacteriaceae, but both were negative. Culture of the urine was not possible because of the anuric condition of the patient. The donor feces infusion was performed according to the protocol as used in the FECAL trial [1]. In summary, donor feces were obtained from a young healthy Caucasian adult, who was periodically screened for various infectious and gastro-intestinal diseases. Feces from the donor were collected and processed within 6 h after production. First, the feces were diluted with sterile saline, and then poured through unfolded gauze in a funnel, in order to obtain a solution which was free of debris and solid particles. This solution was immediately infused in the patient through a nasoduodenal tube. Donor feces infusion was preceded by full colon lavage without prior use of antibiotics. Within the first 2 days after donor feces infusion the patient experienced mild diarrhoea and abdominal cramps, but no other adverse events occurred. Follow-up ESBL swab cultures of the rectum, perineum and throat were taken at week one, two, four, and twelve after the donor feces infusion. During these four follow-up time points the ESBL cultures of the

We carry out small‐scale hydraulic fracture experiments to investigate the physics of hydraulic fracturing. The laboratory experiments are combined with time‐lapse ultrasonic measurements with active sources using both compressional and shear‐wave transducers. For the time‐lapse measurements we focus on ultrasonic measurement changes during fracture growth. As a consequence we can detect the hydraulic fracture and characterize its shape and geometry during growth. Hence, this paper deals with fracture characterization using time‐lapse acoustic data. During fracture growth the acoustic waves generate diffractions at the tip of the fracture. The direct compressional and shear diffractions are used to locate the position of the tip of the fracture. More detailed analysis of these diffractions can be used to obtain information on the geometry and configuration of the fracture tip, including the creation of a zone that is not penetrated by fluid. Furthermore, it appears that the acoustic diffraction is generated mainly at the fluid front and only weakly at the dry tip. In addition, the wavefield that has been transmitted through the hydraulic fracture is measured. Shear‐wave transmissions are shadowed because the shear modulus vanishes inside the fluid‐filled fracture. From this observation we conclude that the fracture is mechanically open. In other words, no friction occurs related to the movement of fracture faces that are in mechanical contact. Compressional transmissions show a distinctive dispersion relative to the measurement in the unfractured medium. This dispersion can be used to determine the width (or aperture) of the fracture by fitting the measured dispersion with the theoretical prediction as a function of the unknown fracture width. We show that the width profile of the fracture can be reconstructed by using a set of transmission records with different source and receiver locations. By performing a validation experiment, we show that the width determination method is reliable, although the estimated fracture width is only a few percent of the incident wavelength. The strength of the method relies on time‐lapse measurements combined with fitting the changes in the measured waveforms during the experiment. The combination of diffractions and transmissions helps us visualize the dynamic process of hydraulic fracture growth. Hence, acoustic measurements with active sources prove their usefulness for fracture characterization.

The Early Warning Score (EWS) is used for early detection of deteriorating vital parameters and has been correlated with adverse outcomes. Unfortunately, neither its value on general wards nor the optimal cut-off value have been investigated. We aimed to find the optimal cut-off value for EWS on general wards, and investigated the possibility to raise this value from EWS ≥ 3 without compromising sensitivity too much.From May 2010 until May 2011, EWS was calculated from vital parameters in all patients in medical and surgical wards in the Medical Centre Alkmaar. Cut-off value was defined as EWS ≥ 3, unless otherwise specified. Six responses were defined and categorised as interventions (infusion prescription, medication changes, ICU consultation) and other actions (no action, change EWS cut-off value, oxygen supplementation), and it was registered whenever the threshold was exceeded.71,911 EWS values were obtained, 31,728 (44%) on medical wards and 40,183 (56%) on surgical wards. On medical wards, the cut-off value was exceeded 3734 times, and response was registered in 29% of the cases with 141 (12%) interventions. On surgical wards, the cut-off value was exceeded 3279 times, and response was registered in 19% of the cases with 633 (36%) interventions. Sensitivity and specificity for EWS ≥ 3 could not be calculated. For a calculated cut-off at EWS ≥ 4, sensitivity decreased to 74%.Raising the EWS threshold to 4 on general wards in the hospital would lead to an unacceptable decrease in sensitivity. Therefore, we recommend that the pre-defined cut-off should remain 3, with the possibility to personalise the threshold.

A low-voltage hybrid switch for laboratory experiments is presented in the paper. The device is composed of IGBT switches in parallel with mechanical switches.

The nature of dynamic correlations in glasses and jammed soft matter remains a puzzle. Despite the strong increase in viscosity, hard-spheres exhibit only moderate increase of dynamic correlations at the glass transition, while recent experiments on soft-spheres suggest that in these systems, correlations grow to macroscopic length. Here, we present a direct real-space analysis of dynamic correlations in hard and soft-sphere glasses. The motion of the particles is imaged directly with confocal microscopy, and the maximum dynamical susceptibility is determined systematically over a range of probe length and time scales. We elucidate the displacement vector field, and analyze correlations in the particles' direction of motion. This allows us to demonstrate the different nature of relaxations in hard and soft-sphere systems. We find that the deeply jammed soft sphere suspension shows by far longer-range dynamic correlations that are characterized by small, remarkably coherent displacements. These observations provide direct evidence of the internal elasticity that governs long-range relaxation modes in soft systems.

Isolated dystonia of trunk and neck muscles without involvement elsewhere has been termed segmental axial dystonia--a rare disorder. We report a 31-year-old man who developed marked dystonia of paraspinal muscles and progressive scoliosis 6 months after a closed head injury. Computed tomography (CT) disclosed three small areas of encephalomalacia, one involving the head of the caudate nucleus. Treatment with trihexyphenidyl resulted in significant improvement of the dystonia and scoliosis.

The aim of this paper is to present a large international field experiment that took place in March-April 2008 on the French Aquitanian coast. During this field experiment, both very small and large spatial and temporal scales have been explored concerning hydrodynamic, sedimentary and morphodynamic processes in the surf and swash zones using innovative methods. This field experiment, one of the largest to take place in Europe (with the COAST 3D project), will provide a unique data set to explore surf zone and swash processes and improve numerical models in presence of very energetic events (5 storms with Hs > 5m) on macrotidal multi-barred sandy beaches. Mots-cles : Experimental – plage sableuse – meso, macrotidal -processus hydrodynamiques – processus sedimentaires – morphodynamique – zones de surf et jet de rive 636 Instrumentation, mesures, imagerie et teledetection

A 44-year-old female was found comatose after attempting suicide. Toxicological screening showed phenobarbital intoxication. The patient was treated symptomatically. After ten days her serum level of phenobarbital still had not decreased and she was not clinically recovered. The patient was transferred to another hospital for hemoperfusion to decrease the level of phenobarbital. After hemoperfusion the level of phenobarbital dropped significantly and the patient recovered neurologically. Phenobarbital has a long elimination half-life and for this reason it is advisable to use means to accelerate clearance until the clinical condition of the patient shows improvement. Multiple-dose activated charcoal effects the elimination of phenobarbital. If elimination needs to be speeded up, then hemoperfusion can be considered. If this technique is unavailable, hemodialysis is a good alternative.

There have been numerous new discoveries of chemical activity at the snow–atmosphere interface over the last 20 years. These observations have stimulated an increasing body of research on snow chemical systems. The findings from this research have led to a general consensus that photochemical processes are the determining control of this snow chemistry. Traditional gasphase chemical reactions have fallen short of fully explaining observed behaviour. Heterogeneous and quasi-liquid layer chemistry has been postulated to play a role in accounting for the discrepancies. The Tkachenko and Kozachkov article is therefore a timely presentation of new ideas for further elucidating snowpack chemical mechanisms. In the following discussion we present recent data relevant to testing hypothesis proposed by Tkachenko and Kozachkov. Some of the hypotheses presented in this paper build upon data from measurements of ozone (O3) in interstitial air of the deep, glacial snowpack at Summit, Greenland, that were presented in our previous work. These experiments reported on positive O3 atmosphere–snowpack gradients, i.e. depleted O3 within the snowpack, and their dynamical behaviour dependent on environmental conditions. We have since taken this research to other locations and further investigated the dependencies of O3 within snow on a variety of parameters. A particular interest of this new research was to further investigate snowpack chemistry in environments with different snowpack conditions (year-round dry, polar snow; seasonal mid-latitude snowpack; snow over permafrost; snow over frozen freshwater lakes). We have also conducted a further 2 years of experiments at Summit, where the measurement depth in the snowpack was increased to 2.5m and experiments were extended year round to include winter observations. Another environment with polar year-round snowpack over glacial ice was investigated at South Pole, Antarctica. From the comparison with these other sites it has become obvious that the Summit snowpack is somewhat unique in that (1) O3 levels within the snowpack are generally higher than observed at other locations, and (2) interstitial air O3 shows a muchmore dynamic dependence on time of day and season than at the other locations that we have investigated. This behaviour might be in agreement with some hypotheses presented by Tkachenko and Kozachkov as they propose that O3 production by the triboelectrical effect would be most pronounced at sites characterised by a thick, glacial snowpack, low humidity, periodic high wind speeds, and low temperatures; all conditions that are typical for Summit. Our series of experiments have shown that different processes dominate snowpack chemistry in non-glacial snowpack. For example, one definite influence on O3 reactions in seasonal, midlatitude snowpack is the role of NO emitted from microbial processes in the subniveal soil. These influences were evident at a high alpine site at Niwot Ridge, CO, in the RockyMountains; snowpack under a canopy at the University of Michigan Biological Station (B. Seok, D. Helmig, M. W. Williams, C. Vogel, P. Curtis, unpubl. data); and snowpack over permafrost at Toolik Field Station, AK (B. Van Dam, D. Helmig, R. Honrath, L. Kramer, C. Toro, unpubl. data). For the Summit snowpack, Helmig et al. noted that O3 atmosphere–snowpack concentration gradients show three

Over 4000 records of the six European Armillaria species were compiled to give distribution maps and host lists for each species. Differences in geographical and altitudinal distribution, pathogenicity, dissemination and ecological role are discussed.

Cervical spondylotic myelopathy appears to result from a combination of factors. The two major components are 1) compressive forces resulting from narrowing of the spinal canal, and 2) dynamic forces owing to mobility of the cervical spine. There is substantial evidence to suggest that the repetitive trauma to the spinal cord that is sustained with movement in a spondylotic canal may be a major cause of progressive myelopathy. Utilization of extensive anterior procedures that remove the diseased ventral features as well as eliminate the dynamic forces owing to the accompanying fusion have grown in popularity. Cervical laminectomy enlarges the spinal canal, but does not reduce the dynamic forces affecting the spinal cord, and may actually increase cervical mobility, leading to a perpetuation of the myelopathy. The authors propose the combination of posterior decompression and Luque rectangle bone fusion to deal with both the compressive and the dynamic factors that lead to cervical spondylotic myelopathy. Ten patients who had advanced myelopathy underwent the combined procedures. Nine of the 10 experienced significant neurological improvement, and the 10th has had no progression. The combination of posterior decompression and Luque rectangle bone fusion may offer a simple, safe, and effective alternative treatment for cervical spondylotic myelopathy.

Cervical spondylotic myelopathy appears to result from a combination of factors. The two major components are 1) compressive forces resulting from narrowing of the spinal canal, and 2) dynamic forces owing to mobility of the cervical spine. There is substantial evidence to suggest that the repetitive trauma to the spinal cord that is sustained with movement in a spondylotic canal may be a major cause of progressive myelopathy. Utilization of extensive anterior procedures that remove the diseased ventral features as well as eliminate the dynamic forces owing to the accompanying fusion have grown in popularity. Cervical laminectomy enlarges the spinal canal, but does not reduce the dynamic forces affecting the spinal cord, and may actually increase cervical mobility, leading to a perpetuation of the myelopathy. The authors propose the combination of posterior decompression and Luque rectangle bone fusion to deal with both the compressive and the dynamic factors that lead to cervical spondylotic myelopathy. Ten patients who had advanced myelopathy underwent the combined procedures. Nine of the 10 experienced significant neurological improvement, and the 10th has had no progression. The combination of posterior decompression and Luque rectangle bone fusion may offer a simple, safe, and effective alternative treatment for cervical spondylotic myelopathy.

Randomly generated polytopes are used frequently to test and compare algorithms for a variety of mathematical programming problems. These polytopes are constructed by generating linear inequality constraints with coefficients drawn independently from a distribution such as the uniform or the normal.

The application of several metal phenyl compounds as active cocatalysts in the homogeneous metathesis of alkenes with WCl or MoCl is described. Promising results have been obtained by using Sn(C6H5)4, Sn(C6H5)3Cl, Pb(C6H5)4 and Pb(C6H5)3Cl.

The application of n-C3H7Li and n-C4H9Li as cocatalysts for the homogeneous metathesis of 2-pentene with WCl6 was investigated. Disproportionation of alkyl radicals generated during the formation of the active catalyst complex results in the production of alkenes, which participate in the metathesis reactions and lead to a small amount of distinct by-products.

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Fur die Metathese ungesattigter Kohlenwasserstoffe in homogenem Milieu wurden mehrere gut verwendbare, aktive und selektive Katalysatoren entwickelt. Sie basieren auf WCl6 und MoCl5 mit Sn(C6H3)4, Sn(C6H5)4 und Pb(C6H5)4 als wichtigsten Cokatalysatoren. Diese Katalysatorsysteme ermoglichen auch die Metathese von Verbindungen mit funktionellen Gruppen wie Fettsaureestern, Halogenkohlenwasserstoffen u. a. Die Metathese von Fettsaureestern eroffnet die Moglichkeit zur Synthese zahlreicher Verbindungen, die bisher nicht bekannt oder nur schwer zuganglich waren, wie bestimmte langkettige, ungesattigte Dicarbonsauren, die sich von Monoenfettsauren, wie Olsaure und Erucasaure, ableiten. Vom technologischen Standpunkt her gesehen, durften namentlich die ungesattigten Dicarbonsauren als Rohstoffe fur die Herstellung ungesattigter Polyester und Polyamide und fur die Synthese bestimmter Riechstoffe von Bedeutung sein. Die Metathese von fetten Olen (Glyzeriden) fuhrt zur Bildung hochmolekularer Verbindungen; die Metathese von halbtrocknenden und trocknenden Olen ergibt im Prinzip die Moglichkeit zur Herstellung von Standolen mit guten trocknenden Eigenschaften. Catalytic Metathesis of Esters of Unsaturated Fatty Acids Several active and selective catalysts have been developed for the metathesis of unsaturated hydrocarbons in homogeneous medium. These are based on WCl6 and MoCl5 with Sn(CH3)4, Sn(C6H5)4 and Pb(C6H6)4 as the most important co-catalysts. These catalyst systems also permit the metathesis of compounds having functional groups, such as esters of fatty acids and halogenated hydrocarbons. The metathesis of esters of fatty acids enables the synthesis of numerous compounds, which so far were either unknown or difficult to synthesize. Such compounds are, for instance, certain long chain unsaturated dicarboxylic acids which are derived from monoenoic fatty acids, such as oleic acid and erucic acid. From technological viewpoint the unsaturated dicarboxylic acids might be significant as raw material for the preparation of unsaturated polyesters and polyamides, as well as for the synthesis of certain flavoring agents. The metathesis of fatty oils (glycerides) leads to the formation of high molecular weight compounds. The metathesis of semi-drying and drying oils offers the possibility to prepare stand oils having good drying properties.