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Copper-carbon composites are a group of materials with excellent mechanical, electrical, thermal, and tribological properties. However, bulk size copper-carbon composites made by the traditional manufacturing processes, like rolling or extrusion, fall short of reaching some of these properties predicted by theory or demonstrated only by samples at centimeter scale or smaller. The two main challenges to the successful scaling-up are: 1) to uniformly disperse carbon in the metal matrix; 2) to avoid degradation due to oxidation or reaction from overheating. In this work, we first demonstrate friction extrusion as a new method to make bulk-size void-free copper-carbon composite wires with homogenized carbon dispersion. Three different carbon varieties, graphite powder, graphene nanopowder, and carbon nanotubes, were added to the copper matrix with the concentration ranging from 0.5 wt% to 15 wt%. Special tooling, processing parameters, and procedures were developed, especially for high carbon content samples. Ten-fold reductions of both copper grain size and carbon particle size were achieved and attributed to the high shear deformation. Energy dispersive X-ray spectrometry indicates the carbon powder was refined to a sub-micron level and uniformly dispersed in the copper matrix. Compared with that of pure copper, the thermal capacity of the composite wire increases by 30 % while density reduces by 29 %.

Next-Generation batteries requires more energy and output power due to the high demands of applications to large-size vehicles, e.g. SUVs and trucks. As a result, multiple dissimilar battery cell tabs are joined together in parallel and carry larger currents in the electrical circuit. Ultrasonic and laser welding have been the two dominant battery cell joining processes in the automotive industry. However, both of them have limitations for joining a large number of stacked battery tabs at one time. Since failure of a single joint can impact the battery and eventually the vehicle, it is important to ensure process robustness and soundness of the resulting battery tab joints. In this study a new joining method, resistive joining (RJ), has been developed for welding multiple dissimilar (copper and aluminum) battery tabs. First, nickel-phosphorus (Ni-P, with ~7 wt% phosphorus) is electroless plated on both sides of selected tabs. In the subsequent resistive joining process, heat is concentrated at the high-electrical-resistivity Ni-P coatings as an electric current is passed through the joint. Aluminum is melted adjacent to the Ni-P coating due to its low melting temperature, and a portion of the Ni-P coating is dissolved into the liquid aluminum and a metallurgical bond is formed as the aluminum re-solidifies. In the meantime, solid-state bonds are formed between the Ni-P coating and copper due to material interdiffusion. Consequently, no Al-Cu intermetallic compound (IMC) is generated at the joint, and the strengths of RJ joints are higher than the base metal when tested in a lap-shear configuration.

Electron beam based additive manufacturing (AM) with copper must consider the high intrinsic thermal conductivity of copper as well as the greater difference between the thermal properties of the AM article and the surrounding or underlying powder bed. Successful processing requires multi-step control of the beam-bed interactions driven by a combination of a priori calculations and real-time monitoring and feedback to achieve melt pool size stability and appropriate bed/article temperatures as thermal boundary conditions vary based on geometry. The objective of this work is to utilize electron imaging to rapidly assess the processing space for copper with a wide shift in thermal boundary conditions using samples with overhang features. A modified commercial Arcam EBM AM system and process parameter space are described that allow successful AM of copper for complex geometries.

Dissimilar materials of copper (Cu) to aluminum (Al) with nickel-phosphorus (Ni-P) coatings were joined using resistance spot welding. The Ni-P coatings were electroless plated on the Al surfaces to eliminate the formation of brittle Cu-Al intermetallic compounds (IMCs) at the faying interface between Cu and Al. Three welding schedules with various heat input were employed to produce different interfacial microstructure. The evolution of interfaces in terms of phase constitution, elemental distribution and defects (gaps and voids) was characterized and the formation mechanisms were elucidated. During the welding process, the bonding between Cu and Ni-P forms through solid-state diffusion, while the faster diffusion rate of Cu relative to Ni and P atoms promotes the generation of sub-micron voids. As the heat input increases, gaps at the Cu/Ni-P interface diminish accompanied by increase of sub-micron voids. A moderate schedule helps to remove the gaps and inhibits the void formation. An Al3Ni layer and nanovoids were found around the interface of Ni-P/Al. The increased heat input decreases the grain size of Al3Ni at the interface by eutectic remelting and increases the nanovoids by enhanced nanoscale Kirkendall effect.

The shear assisted processing and extrusion (ShAPE) process can consolidate powdered materials and simultaneously extrude wire or tube with improved properties. We successfully produced copper wire extrusions from powder and solid materials for the first time. The extrusion pressure in the ShAPE process is at least ten times less than that required for conventional extrusion. We used optical microscopy to inspect and validate the integrity of extrudates, revealing that the microstructure was refined and dynamically recrystallized to equiaxial grains. Compared with annealed copper wire, ShAPE-processed wire showed 80% higher yield strength, 15% higher ultimate tensile strength, and 20% higher ductility. These results were correlated with refined grain size and substructuring observed via electron backscatter diffraction analysis and transmission electron microscopy.

Reaction metallurgical joining (RMJ) was recently developed as a new method for copper-to-copper joining. In this study, a cold metal transfer (CMT) process was investigated to pre-place a low-melting-temperature reaction material between the copper parts to be joined prior to the RMJ process. The joint area is heated via an applied electrical current so that the reaction material dissolves the base metal surface to form a reaction product with a lower solidus temperature than copper. The applied load causes this reaction product, a liquid and/or liquid-solid mixture, to be displaced from the joint, during which time it carries away surface oxides and contaminants. The metallurgically clean opposing surfaces are brought into contact to form a continuous metallurgical bond. The combination of CMT and RMJ methods will potentially provide a robust copper joining process.

Background Asymptomatic carotid artery stenosis (ACS) has a low risk of stroke. To achieve an advantage over noninterventional best medical treatment (BMT), carotid endarterectomy (CEA) or carotid artery stenting (CAS) must be performed with the lowest possible risk of stroke. Therefore, an analysis of risk-elevating factors is essential. Grade of ipsilateral and contralateral stenosis as well as plaque morphology are known risk factors in ACS. Methods The randomized, controlled, multicenter SPACE-2 trial had to be stopped prematurely after recruiting 513 patients. 203 patients were randomized to CEA, 197 to CAS, and 113 to BMT. Within one year, risk factors such as grade of stenosis and plaque morphology were analyzed. Results Grade of contralateral stenosis (GCS) was higher in patients with any stroke (50%ECST vs. 20%ECST; p=0.012). Echolucent plaque morphology was associated with any stroke on the day of intervention (OR 5.23; p=0.041). In the periprocedural period, any stroke was correlated with GCS in the CEA group (70%ECST vs. 20%ECST; p=0.026) and with echolucent plaque morphology in the CAS group (6% vs. 1%; p=0.048). In multivariate analysis, occlusion of the contralateral carotid artery (CCO) was associated with risk of any stroke (OR 7.00; p=0.006), without heterogeneity between CEA and CAS. Conclusion In patients with asymptomatic carotid artery stenosis, GCS, CCO, as well as echolucent plaque morphology were associated with a higher risk of cerebrovascular events. The risk of stroke in the periprocedural period was increased by GCS in CEA and by echolucent plaque in CAS. Due to small sample size, results must be interpreted carefully.

Cold metal transfer (CMT) is an advanced gas metal arc welding (GMAW) process that features a reduced thermal input and improved stability of arc. This report examines the correlations between welder parameters and droplet properties in a one-cycle CMT characteristic where a single droplet was transferred. Through design of experiment and statistical analysis, it is revealed that the weight of the deposited metal droplet has a linear relationship with the output energy of CMT, and the weight can be precisely controlled by adjusting CMT parameters. The droplet surface contact angle is independent of the output energy and has no clear correlation with CMT parameters due to the relatively large thermal conductivity of copper and the heat capacity of the coupon. However, when the thickness of the copper coupon was reduced, the substrate temperature did increase, and the droplet had a smaller contact angle. In addition, the metal droplet transfer during the CMT process is subjected to a phenomenon known as magnetic arc blow which affects the landing position. When the ground connection was not in line with the electrode, the bent electric current path deflected the welding arc away from the ground connection. When the ground connection was attached underneath the projection path of the electrode, the droplet deflection disappeared. The knowledge obtained in this study is crucial to optimizing the CMT process and improving the quality of the subsequent copper joining processes.

International audience; Droplet volume and temperature affect contact angle significantly. Phase change heat transfer processes of nanofluids – suspensions containing nanometre-sized particles – can only be modelled properly by understanding these effects. The approach proposed here considers the limiting contact angle of a droplet asymptotically approaching zero-volume as a thermophysical property to characterise nanofluids positioned on a certain substrate under a certain atmosphere.Graphene oxide, alumina, and gold nanoparticles are suspended in deionised water. Within the framework of a round robin test carried out by nine independent European institutes the contact angle of these suspensions on a stainless steel solid substrate is measured with high accuracy. No dependence of nanofluids contact angle of sessile droplets on the measurement device is found. However, the measurements reveal clear differences of the contact angle of nanofluids compared to the pure base fluid.Physically founded correlations of the contact angle in dependency of droplet temperature and volume are obtained from the data. Extrapolating these functions to zero droplet volume delivers the searched limiting contact angle depending only on the temperature. It is for the first time, that this specific parameter, is understood as a characteristic material property of nanofluid droplets placed on a certain substrate under a certain atmosphere. Together with the surface tension it provides the foundation of proper modelling phase change heat transfer processes of nanofluids.

Copper-graphite composites wires are manufactured by a novel friction stir processing named Shear-Assisted Processing and Extrusion (ShAPE). Two types of precursors have been prepared respectively: a blend of copper and graphite powder; solid copper cylinders having pre-drill holes filled with graphite powder. The precursor material was consolidated and extruded in one step by ShAPE. Up to 800 mm long defect-free wires were produced. The metallographic inspection on both transverse cross-section and longitudinal cross-section confirms the good integrity of the ShAPE Cu-graphite wires. Energy dispersive spectroscopy and electron backscatter diffraction indicate the graphite particles were reduced to sub-micro size and uniformly dispersed in the copper matrix. The ultrafine graphite particle inhibits the grain growth thus improving the hardness. The processing temperature is below 550 °C which is much lower compared to conventional manufacturing methods.

Mechanical degradation due to brittle intermetallic compounds (IMCs) formed at the faying interface is a predominant deficiency in dissimilar metal joints. In copper/aluminum (Cu/Al) joints, additional defects (such as partially-bonded interfaces, porosity and cracks) lead to further weakened strength and lowered electrical conductivity. In this study, nickel‑phosphorus (Ni-P) coatings are deposited on Al to address these issues. With the aid of Ni-P coatings, the detrimental Cu-Al IMC is eliminated, a donut-shaped weld with a partially-bonded interface is evolved into an hourglass-shaped weld with a fully-bonded interface, while the porosity and cracks are inhibited. Numerical simulations indicate that, during the welding without Ni-P coating, the Al oxide aggravates the inhomogeneity of heat generation at the Cu/Al interface, promoting the formation of donut-shaped weld and defects. Microstructural characterization suggests that the Ni-P coatings obstruct the Cu-Al interdiffusion which results in CuAl2-free interfaces, while the amorphous Ni-P convert into eutectic microstructure composed of nanocrystalline Ni and fine Ni3P grains through a solid-state transformation. Using the Ni-P coatings, joints gain an improvement of 140% in lap-shear peak load and a 25-fold increase in lap-shear maximum elongation, as well as an 84% reduction in electrical resistance.

Basilar artery occlusion (BAO) is one of the most devastating forms of stroke and few patients have good outcomes without recanalization. Most centers apply recanalization therapies for BAO up to 12-24 hours after symptom onset, which is a substantially longer time window than the 4.5 hours used in anterior circulation stroke. In this speculative synthesis, we discuss recent advances in BAO treatment in order to understand why and under which circumstances longer symptom duration might not necrotize the brainstem and turn therapeutic attempts futile. We raise the possibility that distinct features of the posterior circulation, e.g., highly developed, persistent collateral arterial network, reverse filling of the distal basilar artery, and delicate plasma flow siding the clot, might sustain brittle patency of brainstem perforators in the face of stepwise growth of the thrombus. Meanwhile, the tissue clock characterizing the rapid necrosis of a typical anterior circulation penumbra will not start. During this perilous time period, recanalization at any point would salvage the brainstem from eventual necrosis caused by imminent reinforcement and further building up of the clot.

© 2017 IEEE. A new and improved technique is presented for the measurement of iron loss in motor stators. The most accurate existing technique rotates dummy-test rotors, one for each field strength of interest, inside the stators to be tested and measures the reaction torque on the stators. The new technique uses a wound 'rotor' component that does not rotate mechanically but does rotate electrically. Therefore, the speed and magnitude of the rotating flux can be controlled electrically without the inherent difficulties of rotating mechanically at high speed and without building different dummy-test rotors for each field strength test.

BACKGROUND AND PURPOSE: Acute BAO is a devastating neurological condition associated with a poor clinical outcome and a high mortality rate. Recanalization has been identified as a major prognostic factor for good outcome in BAO. Mechanical thrombectomy using retrievable stents is an emerging treatment option for acute stroke. First clinical trials using stent retrievers have shown promising high recanalization rates. However, these studies mainly included large artery occlusions in the anterior circulation with only a few or single cases of BAO. Therefore, the purpose of this study was to evaluate technical feasibility, safety, and efficacy of mechanical thrombectomy using retrievable stent in the treatment of acute BAO. MATERIALS AND METHODS: Fourteen consecutive patients with BAO undergoing endovascular therapy using retrievable stents (Solitaire FR Revascularization Device) were included. Additional multimodal treatment approaches included thromboaspiration, intravenous and/or intra-arterial thrombolysis, and PTA/ permanent stent placement. Recanalization rates after multimodal therapy and stent retrieval were determined. Clinical outcome and mortality were assessed 3 months after treatment. RESULTS: Median patient age was 64.5 years (range 55–85). Median NIHSS score at presentation was 21 (range 5–36). Overall, successful recanalization (TICI 3 or 2b) was achieved in all patients (TICI 3 in 78.6%, 11/14). In 4 patients (28.6%), insufficient recanalization after stent retrieval was due to an underlying atherosclerotic stenosis. Additional deployment of a permanent intracranial stent was performed in 3 patients (21.4%) and PTA alone in 1 patient (7.1%), resulting in final TICI 3 in 1 patient and TICI 2b in 3 patients. Stent retrieval alone was performed in 4 patients (28.6%). Average number of device passes was 1.3 (range 1–3). Median procedure time to maximal recanalization was 47 minutes (range 10–252). No device-related complications or thromboembolic occlusion of a previously unaffected artery occurred. There was no symptomatic intracranial hemorrhage. At 3 months, good functional outcome (mRS 0–2) was observed in 28.6% (4/14); overall mortality was 35.7% (5/14). CONCLUSIONS: A multimodal endovascular approach using retrievable stents in BAO has high recanalization rates, with very low complication rates. Underlying atherothrombotic stenotic lesions of the basilar artery may still necessitate additional permanent stent placement to achieve complete recanalization.

Ziel der Akuttherapie des ischamischen Schlaganfalls ist die rasche Rekanalisation der verschlossenen Hirnarterie. Endovaskulare Verfahren haben insbesondere bei Verschlussen groser Hirnarterien hohere Rekanalisationsraten als die intravenose Thrombolyse (IVT). Die mechanische Thrombektomie mit dem Merci-Retriever ist daher seit 2004 von der FDA in Erganzung zur IVT oder bei Kontraindikationen einer IVT bis 8 h nach Infarktbeginn zugelassen. Mit diesem System konnte eine Rekanalisationsrate von 55 % erreicht werden, sodass weiteres Verbesserungspotenzial bestand. Seit 2008 darf auch das Penumbra-System angewendet werden. Der neueste endovaskulare Behandlungsansatz mit wieder entfernbaren intrakraniellen Stents zeigt die bisher hochsten Rekanalisationsraten von uber 90 % bei gleichzeitiger Reduktion der Behandlungsdauer ohne zunehmende Komplikationsrate. Die bisherigen ermutigenden Ergebnisse legen eine kombinierte Therapie nahe, bei der eine IVT auch in kleineren Hausern begonnen werden kann, um dann in einem spezialisierten neuroradiologischen Zentrum bei persistierendem Verschluss durch die endovaskulare Rekanalisation erganzt zu werden (sog. Bridging-Therapie). Patienten auserhalb des 4,5 h-Zeitfensters fur die IVT konnen bis 8 h nach Infarktbeginn mittels mechanischer Thrombektomie therapiert werden.

BACKGROUND AND PURPOSE: BCT is a benign entity, whose appearance on conventional MR imaging makes its differentiation from neoplastic, inflammatory, or subacute ischemic disease challenging. SWI is sensitive to susceptibility effects from deoxyhemoglobin with excellent spatial resolution. Only scarce case reports have described the utility of SWI in cases of BCT. Our aim was to show the diagnostic value of SWI applied to a larger series of cases. MATERIALS AND METHODS: This was an observational retrospective study of 33 BCTs in 27 consecutive patients examined from August 2009 to January 2011 with MR imaging, including SWI. Morphology, signal intensity characteristics, and additional vascular malformations were analyzed. Preceding or follow-up examinations were available in 18 patients with a median time interval of 14.5 months (range, 2–115 months). RESULTS: Twenty-five pontine and 8 supratentorial BCTs demonstrated distinct signal-intensity loss on SWI in combination with postcontrast enhancement. Mean lesion diameter was 4.9 mm (range, 1.5–17 mm). Thirty-nine percent showed slight signal-intensity changes on T1 and/or T2; the remainder were isointense to normal brain. In 30%, a prominent draining vessel was observed. Additional cerebral vascular malformations were found in 5 patients. CONCLUSIONS: SWI represents a valuable tool for confirmation of presumed BCT. Demonstration of signal-intensity loss on SWI in an enhancing focal brain lesion, otherwise unremarkable on conventional MR images, is highly specific for BCT, thus excluding serious pathology and reassuring the patient and referring physician. This is particularly helpful for BCT in less typical locations.

BACKGROUND AND PURPOSE: CBV is a vital perfusion parameter in estimating the viability of brain parenchyma (eg, in cases of ischemic stroke or after interventional vessel occlusion). Recent technologic advances allow parenchymal CBV imaging tableside in the angiography suite just before, during, or after an interventional procedure. The aim of this work was to analyze our preliminary clinical experience with this new imaging tool in different neurovascular interventions. MATERIALS AND METHODS: FPD-CBV measurement was performed on a biplane FPD angiographic system. Eighteen patients (11 women, 7 men) were examined (age range, 18–86 years; median, 58.7 years). In the 10 patients with stroke, the extent of intracranial hypoperfusion was evaluated. The remaining 8 patients had an intracranial hemorrhage; periprocedural CBV was evaluated during the course of interventional treatment. RESULTS: In the 18 cases studied, 23 CBV measurements were performed. Twenty acquisitions were of sufficient diagnostic quality. The remaining 3 acquisitions failed technically, 1 due to motion artifacts and 2 due to injection technique and/or hardware failure. CONCLUSIONS: FPD-CBV measurement in the angiography suite provides a feasible and helpful tool for peri-interventional neuroimaging. It extends the intraprocedural imaging modalities to the level of tissue perfusion. However, the technique has technical limitations and shows room for improvement in the future.

BACKGROUND AND PURPOSE: Retrievable stents combine the high recanalization rate of stents and the capability of removing the thrombus offered by mechanical thrombectomy devices. We hypothesized that retrievable stents shorten time to recanalization in the multimodal approach for endovascular stroke treatment. MATERIALS AND METHODS: Forty consecutive patients with acute ischemic stroke and undergoing endovascular therapy were included. Treatment included thromboaspiration, thrombus disruption, thrombolysis, PTA, and stent placement. In 17 patients, a retrievable stent was used (group A) in addition to multimodal therapy. The remaining 23 patients constituted group B. Baseline characteristics, occlusion sites, urokinase dose, recanalization rate, and time to recanalization were compared between the groups. RESULTS: Median NIHSS scores were higher in group A compared with group B on admission (19 versus 12.5; P = .018) but were not significantly different at day 1 (14 versus 10; P = .6). Intra-arterial thrombolysis was used in significantly fewer patients of group A than group B (53% versus 87%, respectively; P = .017), and median urokinase dose was lower in group A than in group B (250,000 IU versus 700,000 IU; P = .006). Time to recanalization was significantly shorter in group A compared with group B (median time to recanalization 52.5 minutes versus 90 minutes, respectively; P = .001). Recanalization rate was higher in group A than group B (94% versus 78%; P = .17). CONCLUSIONS: Addition of retrievable stents to the multimodal endovascular approach for acute ischemic stroke treatment significantly reduces time to recanalization and further increases the recanalization rate.

BACKGROUND AND PURPOSE: The use of self-expanding retrievable stents is an emerging and promising treatment strategy for acute stroke treatment. The concept combines the advantages of stent deployment with immediate flow-restoration and of mechanical thrombectomy with definitive thrombus removal. The present study was performed to gain more knowledge about the principle of combined flow restoration and thrombectomy in an established animal model using radiopaque thrombi evaluating efficiency, thrombus-device interaction and possible complications of the first dedicated flow-restoration and mechanical thrombectomy device. MATERIALS AND METHODS: The Solitaire FR (4 × 20 mm) was evaluated in 15 vessel occlusions in an established animal model in swine. Flow-restoration effect at T0, T5, and T10; recanalization rate after retrieval; thromboembolic events; and complications were assessed. Radiopaque thrombi (10-mm length) were used for visualization of thrombus-device interaction during application and retrieval. RESULTS: Immediate flow restoration was achieved in 80% of occlusions. Mean percentage of recanalization compared with the initial vessel diameter at T0 was 30.8%; at T5, 30.7%; and at T10, 25.4%. Re-occlusion occurred in 20.0% between T0 and T5 and in 13.3% between T5 and T10. Complete recanalization (TICI 3) after retrieval was achieved in 86.7%. In 2 cases (13.3%), partial recanalization was achieved, with the remaining thrombus in a side branch (TICI 2b). No thromboembolic event was observed. The assessment of thrombus-device interaction illustrated the compression of the thrombus against the vessel wall during deployment leading to partial flow restoration. During retrieval, the thrombus was retained by the stent struts even during the passage of vessel curvatures. CONCLUSIONS: The Solitaire FR is a safe and effective combined flow-restoration and thrombectomy device in vivo. Partial flow restoration is achieved by thrombus compression immediately after deployment, but flow restoration decreases afterward until final retrieval results in maximal recanalization.

BACKGROUND AND PURPOSE: The major goal of acute ischemic stroke treatment is fast and sufficient recanalization. Percutaneous transluminal balloon angioplasty (PTA) and/or placement of a stent might achieve both by compressing the thrombus at the occlusion site. This study assesses the feasibility, recanalization rate, and complications of the 2 techniques in an animal model. MATERIALS AND METHODS: Thirty cranial vessels of 7 swine were occluded by injection of radiopaque thrombi. Fifteen vessel occlusions were treated by PTA alone and 15, by placement of a stent and postdilation. Recanalization was documented immediately after treatment and after 1, 2, and 3 hours. Thromboembolic events and dissections were documented. RESULTS: PTA was significantly faster to perform (mean, 16.6 minutes versus 33.0 minutes for stent placement; P < .001), but the mean recanalization rate after 1 hour was significantly better after stent placement compared with PTA alone (67.5% versus 14.6%, P < .001). Due to the self-expanding force of the stent, vessel diameter further increased with time, whereas the recanalization result after PTA was prone to reocclusion. Besides thromboembolic events related to the passing maneuvers at the occlusion site, no thrombus fragmentation and embolization occurred during balloon inflation or stent deployment. Flow to side branches could also be restored at the occlusion site because it was possible to direct thrombus compression. CONCLUSIONS: Stent placement and postdilation proved to be much more efficient in terms of acute and short-term vessel recanalization compared with PTA alone.

OBJECTIVES: To determine the accuracy of automated vessel-segmentation software for vessel-diameter measurements based on three-dimensional contrast-enhanced magnetic resonance angiography (3D-MRA). METHOD: In 10 patients with high-grade carotid stenosis, automated measurements of both carotid arteries were obtained with 3D-MRA by two independent investigators and compared with manual measurements obtained by digital subtraction angiography (DSA) and 2D maximum-intensity projection (2D-MIP) based on MRA and duplex ultrasonography (US). In 42 patients undergoing carotid endarterectomy (CEA), intraoperative measurements (IOP) were compared with postoperative 3D-MRA and US. RESULTS: Mean interoperator variability was 8% for measurements by DSA and 11% by 2D-MIP, but there was no interoperator variability with the automated 3D-MRA analysis. Good correlations were found between DSA (standard of reference), manual 2D-MIP (rP=0.6) and automated 3D-MRA (rP=0.8). Excellent correlations were found between IOP, 3D-MRA (rP=0.93) and US (rP=0.83). CONCLUSION: Automated 3D-MRA-based vessel segmentation and quantification result in accurate measurements of extracerebral-vessel dimensions.

This article provides an overview on the actual state of the interventional neuroradiological management of carotid cavernous fistulas depending on their anatomy and pathophysiology. The results are based on our experience gained during the treatment of patients with complex CCF during the last 15 years. Indications, procedures, and results of transarterial, transvenous and combined arteriovenous approaches for balloon occlusion, embolization, coiling and stenting of these lesions are discussed. Progress in this field is constant so that new technical advances are expected to improve the safety and to expand the indications for these procedures in the future.

General Motors has developed Quick Plastic Forming (QPF) as a hot blow forming process capable of producing aluminum closure panels at high volumes. This technology has been successfully implemented for automotive liftgates and decklids with complex shapes. This talk will review key elements of the QPF process, describe some of the technical achievements realized in this process, and identify areas for future research in process, material, and lubricant development.

Door-in-white structures of left hand, front and rear steel (baseline) doors were redesigned to facilitate their manufacture from hot-blow-formed aluminum panels. The door designs each incorporated a “STAR” multi-purpose reinforcement panel. The STAR panel fulfills the functions of the traditional door intrusion beam and the outer belt line reinforcement, and also provides additional reinforcement to one of the door shut-faces. Prototype door-in-white structures were manufactured from quick plastically formed aluminum panels. Mass savings of 5.1 kg/door (front) and 4.7 kg/door (rear) were obtained in the prototype aluminum doors relative to their steel counterparts. The aluminum doors met all static stiffness criteria with the exception of upper header stiffness. FMVSS 214 testing indicated that the doors exhibited acceptable intrusion resistance when tested in the production vehicle (steel) body system. The aluminum doors also performed well in a dynamic LINCAP (full vehicle side impact) test.

Traditionally iron loss in motor stators is measured using loss separation, where overall loss is measured and then other losses like windage, bearings, copper, and rotor losses subtracted. This technique is unsatisfactory because the stator iron loss is typically smaller than the other losses subtracted and therefore a small error percentage wise in one of these other losses leads to a large error in the iron loss. A new technique is described that directly measures the stator iron loss and therefore offers much improved accuracy. This new technique is then applied to a series of known difficult measurements, like effect of temperature on iron loss, compression on iron loss, etc., to demonstrate its veracity and usefulness and to quantify these effects accurately for the first time.

Item does not contain fulltext BACKGROUND: The presence of prodromal transient ischemic attacks (TIAs) has been associated with a favorable outcome in anterior circulation stroke. We aimed to determine the association between prodromal TIAs or minor stroke and outcomes at 1 month, in the Basilar Artery International Cooperation Study, a registry of patients presenting with an acute symptomatic and radiologically confirmed basilar artery occlusion. METHODS: A total of 619 patients were enrolled in the registry. Information on prodromal TIAs was available for 517 patients and on prodromal stroke for 487 patients. We calculated risk ratios and corresponding 95% confidence intervals (CIs) for poor clinical outcome (modified Rankin Scale score >/=4) according to the variables of interest. RESULTS: Prodromal minor stroke was associated with poor outcome (crude risk ratio [cRR], 1.26; 95% CI, 1.12-1.42), but TIAs were not (cRR, .93; 95% CI, .79-1.09). These associations remained essentially the same after adjustment for confounding variables. CONCLUSIONS: Prodromal minor stroke was associated with an unfavorable outcome in patients with basilar artery occlusion, whereas prodromal TIA was not.

Background and Purpose— Lesion volume on diffusion-weighted magnetic resonance imaging (DWI) before acute stroke therapy is a predictor of outcome. Therefore, patients with large volumes are often excluded from therapy. The aim of this study was to analyze the impact of endovascular treatment in patients with large DWI lesion volumes (>70 mL). Methods— Three hundred seventy-two patients with middle cerebral or internal carotid artery occlusions examined with magnetic resonance imaging before treatment since 2004 were included. Baseline data and 3 months outcome were recorded prospectively. DWI lesion volumes were measured semiautomatically. Results— One hundred five patients had lesions >70 mL. Overall, the volume of DWI lesions was an independent predictor of unfavorable outcome, survival, and symptomatic intracerebral hemorrhage ( P 70 mL, 11 of 31 (35.5%) reached favorable outcome (modified Rankin scale score, 0–2) after thrombolysis in cerebral infarction 2b-3 reperfusion in contrast to 3 of 35 (8.6%) after thrombolysis in cerebral infarction 0-2a reperfusion ( P =0.014). Reperfusion success, patient age, and DWI lesion volume were independent predictors of outcome in patients with DWI lesions >70 mL. Thirteen of 66 (19.7%) patients with lesions >70 mL had symptomatic intracerebral hemorrhage with a trend for reduced risk with avoidance of thrombolytic agents. Conclusions— There was a growing risk for poor outcome and symptomatic intracerebral hemorrhage with increasing pretreatment DWI lesion volumes. Nevertheless, favorable outcome was achieved in every third patient with DWI lesions >70 mL after successful endovascular reperfusion, whereas after poor or failed reperfusion, outcome was favorable in only every 12th patient. Therefore, endovascular treatment might be considered in patients with large DWI lesions, especially in younger patients.

To determine the safety, efficacy, and predictors of favourable outcome of intra-arterial thrombolysis in acute stroke attributable to internal carotid "T"occlusionThe authors analysed 24 consecutive patients with T occlusions of the internal carotid artery treated by local intra-arterial thrombolysis using urokinase.The median baseline National Institutes of Health Stroke Scale was 19. The average time from symptom onset to treatment was 237 minutes. Four patients (16.6%) had a favourable (modified Rankin Scale score (mRS/=2)) and 10 patients (41.7%) a poor outcome (mRS 3 or 4) after three months. Ten patients (41.7%) died. One symptomatic intracerebral haemorrhage (4.2%) occurred. Partial recanalisation of the intracranial internal carotid artery was achieved in 15 (63%), of the middle cerebral artery in four (17%), and of the anterior cerebral artery in eight patients (33%). Complete recanalisation never occurred. Sufficient leptomeningeal collaterals as seen on arteriography (p=0.02) and age60 years (p=0.012) were the only predictors of favourable clinical outcome.Acute stroke attributable to carotid T occlusion remains a condition with a generally poor prognosis even when intra-arterial thrombolysis is performed. Favourable outcome was seen only in patients with sufficient leptomeningeal collaterals.

We present primary results from the Sequencing Quality Control (SEQC) project, coordinated by the US Food and Drug Administration. Examining Illumina HiSeq, Life Technologies SOLiD and Roche 454 platforms at multiple laboratory sites using reference RNA samples with built-in controls, we assess RNA sequencing (RNA-seq) performance for junction discovery and differential expression profiling and compare it to microarray and quantitative PCR (qPCR) data using complementary metrics. At all sequencing depths, we discover unannotated exon-exon junctions, with >80% validated by qPCR. We find that measurements of relative expression are accurate and reproducible across sites and platforms if specific-filters are used. In contrast, RNA-seq and microarrays do not provide accurate absolute measurements, and gene-specific biases are observed for all examined platforms, including qPCR. Measurement performance depends on the platform and data analysis pipeline, and variation is large for transcript-level profiling. The complete SEQC data sets, comprising >100 billion reads (10Tb), provide unique resources for evaluating RNA-seq analyses for clinical and regulatory settings.

Fragestellung: Das Konzept der Forschungsgruppe Bern fur eine rahmenlose bildinteraktive Navigationschirurgie an der Schadelbasis und den Nasennebenhohlen wird vorgestellt.

BACKGROUND AND PURPOSE: Currently, several new stent retriever devices for acute stroke treatment are under development and early clinical evaluation. Preclinical testing under standardized conditions is an important first step to evaluate the technical performance and potential of these devices. The aim of this study was to evaluate the immediate recanalization effect, recanalization efficacy, thrombus-device interaction, and safety of a new stent retriever intended for thrombectomy in patients with acute stroke. MATERIAL AND METHODS: The pREset thrombectomy device (4 × 20 mm) was evaluated in 16 vessel occlusions in an established swine model. Radiopaque thrombi (10-mm length) were used for visualization of thrombus-device interaction during application and retrieval. Flow-restoration effect immediately after deployment and after 5-minute embedding time before retrieval, recanalization rate after retrieval, thromboembolic events, and complications were assessed. High-resolution FPCT was performed to illustrate thrombus-device interaction during the embedding time. RESULTS: Immediate flow restoration was achieved in 75% of occlusions. An increase or stable percentage of recanalizations during embedding time before retrieval was seen in 56.3%; a decrease, in 12.5%; reocclusion of a previously recanalized vessel, in 18.8%; and no recanalization effect at all, in 12.5%. Complete recanalization (TICI 3) after retrieval was achieved in 93.8%; partial recanalization (TICI 2b), in 6.2%. No distal thromboembolic events were observed. High-resolution FPCT illustrated entrapment of the thrombus between the stent struts and compression against the contralateral vessel wall, leading to partial flow restoration. During retrieval, the thrombus was retained in a straight position within the stent struts. CONCLUSIONS: In this experimental study, the pREset thrombus retriever showed a high recanalization rate in vivo. High-resolution FPCT allows detailed illustration of the thrombus-device interaction during embedding time and is advocated as an add-on tool to the animal model used in this study.

The therapy of acute ischemic stroke aims at fast recanalization of the occluded brain vessel. In contrast to intravenous thrombolysis (IVT), endovascular approaches yield higher recanalization rates especially in large vessel occlusions. Mechanical thrombectomy with the Merci Retriever received FDA approval in 2004 as an adjunct to IVT or in the case of failed recanalization after IVT. The time window for treatment is 8 h from stroke onset. However, the recanalization rate was 55 %, still leaving space for further improvement. In addition to the Merci Retriever, the Penumbra System received FDA approval in 2008. The newest endovascular approach comprising retrievable intracranial stents results in an increased recanalization rate exceeding 90 % and has markedly reduced the time to recanalization. On the other hand, the complication rate has not increased yet. These promising results suggest a combined therapy for acute ischemic stroke. In a first step IVT can be started independently of the size of the treating hospital and in a next step the patient is transferred to a neuroradiological center. If vessel occlusion persists, additional endovascular recanalization is performed (bridging concept). Patients who don't qualify for IVT are candidates for mechanical thrombectomy up to 8 h after stroke onset.

BACKGROUND AND PURPOSE: Angioplasty and stenting of the IA have been reported with high technical and clinical success rates, low complication rates and good mid-term patency rates. Different antegrade or retrograde endovascular catheter-based approaches and combinations with surgical exposure of the CCA are used. The purpose of this study was to determine safety, efficacy and mid-term clinical and radiological outcome of the stent-assisted treatment of atherosclerotic stenotic disease of the IA with special focus on the different technical approaches. MATERIALS AND METHODS: Between 1996 and 2008, 18 patients (12 men, 6 women) with symptomatic high-grade stenosis (>80%) of the IA were treated with endovascular stent placement. Their mean age was 60.4 years (range, 48–78 years). Mean angiographic and clinical follow-up was 2.7 years (range, 0.3–9.1 years). Clinical follow-up was performed by using the mRS at hospital discharge, routine follow-up controls, and a questionnaire. In 11 patients, a percutaneous approach was used. In 7 patients, the lesions were accessed retrogradely through a cervical cut-down with common carotid arteriotomy. In 2 patients, a simultaneous ipsilateral carotid endarterectomy was performed. RESULTS: In all patients, primary stent placement was performed. There were 2 procedure-related transient complications (11.1%) due to cerebral embolism without permanent morbidity or mortality. During the follow-up, all patients showed improvement of the preprocedural symptoms. At the latest clinical follow-up (mean, 2.7 years), all patients showed an excellent or good outcome (mRS, 0 or 1). In 2 patients (11.1%), a secondary stent placement was needed due to a significant symptomatic in-stent stenosis. CONCLUSIONS: Percutaneous and open retrograde stenting of high-grade stenosis of the IA is a viable less invasive alternatives to open bypass surgery with good midterm clinical results and patency rates.

5 unusual cases of cerebral tuberculosis are reported. Three of the cases initially showed the typical history and aspect of herpes simplex encephalitis, and two of a cerebral tumour. Both CT and MRI, and also the clinical neurological symptoms, were confusing. Microbiological culture in three and histological preparation in two cases confirmed the diagnosis of cerebral tuberculosis. Three cases showed the development of tuberculomas under therapy. The study of the literature suggests that this is not rare, which is explained by pathogenetic reflexions concerning the allergic genesis of the tuberculomas.

Die Pathophysiologie des akuten Hirnschlags und des akuten Myokardinfarkts sind ahnlich: Bei beiden Krankheitsbildern droht ein akuter Zelltod als Folge eines akuten Gefassverschlusses. Eine rasche Eroff­ nung des verschlossenen Gefasses ist daher Hauptziel der Akutbehandlung. Die Therapiekonzepte im Alltag unterscheiden sich: In der Kardiologie hat die Koro­ narangiographie mit Angioplastie und Stenting die in­ travenose Thrombolyse (IVT) – einst Goldstandard in der Behandlung des Herzinfarkts – langst abgelost. Die endovaskulare Behandlung zeigte im Vergleich zur IVT eine bessere Gefassrekanalisation, weniger lebensbedrohliche Blutungen und ein besseres Schick­ sal der Patienten. In der Neurologie ist die IVT seit Mitte der neunziger Jahre in den meisten «Stroke Units» die Therapie der Wahl zur Akutbehandlung des Hirnschlags. Bei einem Teil der Hirnschlagpatien­ ten zeigt die IVT enttauschende Resultate, und trotz vielversprechender Resultate konnten sich die intra­ arterielle Thrombolyse (IAT) und mechanische Reka­ nalisation bisher nur in einzelnen Stroke Units durch­ setzen. Das Schicksal nach einem Hirnschlag wird durch folgende Faktoren bestimmt: Patientenalter, Schwere­ grad des neurologischen Defizits, Grosse und Loka­ lisation des Infarkts, Zeitintervall zwischen Symptom­ beginn und Behandlung, Ausmass der Gefassrekana­ lisation und Komplikationen wie intrazerebrale Blu­ tungen. Da Alter, Schweregrad sowie Grosse und Lokalisation des Hirnschlags nicht beeinflussbar sind, besteht das Behandlungsziel in einer moglichst raschen und vollstandigen Gefassrekanalisation bei gleichzeitiger Vermeidung von Blutungskomplikatio­ nen.