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Conventional processes like shearing dispose a lack in efficiency and formability to manufacture functional components with a high geometric variety. A possibility to allow the efficient and sustainable manufacturing is the application of innovative forming operations like orbital forming. Thus, a strain-hardened component with a load-adapted thickness profile can be manufactured in a single-stage process. Thereby, the control of the material flow could be identified as major challenge due to the three-dimensional stress and strain state. In order to reduce the parts weight and simultaneously guarantee the same level of performance, conventional steel is substituted by lightweight materials such as precipitation hardenable aluminum alloys. However, new challenges arise due to the reduced formability of aluminum compared to conventional steel. In recent research, the potential of a short-term heat treatment to enlarge the formability could be shown. The presented process locally reduces the materials strength, thus allowing a control of the material flow by the interaction between softened areas and areas, which offer the initial conditions. In this contribution, the influence on the formability of orbital formed components manufactured out of the precipitation hardenable aluminum alloy EN AW 6016 by a local short-term heat treatment is investigated. Different geometry-based heat treatment layouts are applied in order to maximize the thickening on different radial positions. The potential to enhance the formability is evaluated by comparing geometrical and mechanical properties of the components manufactured in the conventional process route and with a previous heat treatment. The analysis of radial cross-sections and the hardness distribution reveals the positive influence of the heat treatment but also points out the geometrical dependency of the effect due to the characteristic material flow in orbital forming.

Nowadays, the manufacturing industry faces opposing challenges like a reduction of carbon dioxide on the one hand and on the other hand an increasing weight due to higher safety standards and additional functions. Concepts like lightweight design and functional integration are essential to ensure a sustainable and individual mobility. Gear systems consist of multi-functional parts with a varying sheet thickness and different geometric elements. Since conventional manufacturing processes like shearing are reaching their limits due to complexity and a lack in efficiency, the application of Tailored Blanks is a promising approach to meet these requirements. Manufactured by orbital forming, these process-adapted blanks dispose a high material efficiency. A tumbling motion of the upper punch enables the material distribution, realizing functional components with different material thickenings. The substitution of steel by aluminum is a common approach to meet the demands of lightweight construction. However, the use of aluminum results in a decreased formability at a constant level of strength. In order to enhance the local forming limits, a short-term heat treatment can be applied, reducing the materials’ strength, whereas the untreated areas still offer the initial properties. To transfer the results of fundamental research in Sheet-Bulk Metal Forming with conventional steel to the use of lightweight material, the precipitation hardenable aluminum alloy EN AW 6016 is investigated in an orbital forming process. Since the formability of aluminum is limited and the material flow during the process is three-dimensional, different heat treatment strategies are applied to a rotational-symmetric Tailored Blank and the resulting components are investigated regarding their geometry and mechanical properties. To increase the geometric complexity with regard to an industrial application, the transferability to a cyclic-symmetric layout is analyzed. To evaluate the potential of the heat treatment, the treated components are compared to Tailored Blanks manufactured without heat treatment.

Summary Cerebral autoregulation is particularly challenged in acute ischemic stroke. In this review we summarize the data of our previous studies on autoregulation regarding the effect of rtPA on autoregulation after stroke. A pooled analysis of two studies (45 patients) has shown a worsening of the autoregulatory index Mx between an early (first 48 h) and late (days 5–7) measurement. This increase was more pronounced on affected sides than on unaffected sides. Poor ipsilateral Mx was associated with a greater volume of MCA infarction at a late measurement and related to poor clinical outcome. Overall, autoregulatory impairment tends to increase mainly in large infarction and generalize to the contralateral side during the first days after ischemic stroke. As a limitation, transcranial Doppler sonography does not allow to detect focal areas of dysautoregulation in smaller strokes. To better understand the temporal and spatial dynamics of dysautoregulation in acute stroke in relation to the type and size of infarction, new bedside hemodynamic monitoring techniques (like multi-channel near-infrared spectroscopy) are needed.

The phase shift between oscillations of blood pressure (BP) and Doppler middle cerebral artery flow velocity (MCAFV) reflects continuous cerebral autoregulatory action. It is not known whether a similar phase shift exists for cortical hemodynamics ('microvascular level') assessed by near infrared spectroscopy (NIRS) and what the effects are of pathological conditions. This study investigates the phase relations between oscillations of BP, MCAFV and NIRS parameters in 38 healthy older adults and 28 patients with unilateral severe obstructive carotid disease. BP was recorded noninvasively by finger plethysmography. Stable 0.1 Hz oscillations of all hemodynamic parameters were induced by regular breathing at a rate of 6/min. Basic results were that: (1) BP-induced cortical microvascular oscillations (NIRS) follow those of macrovascular oscillations (MCAFV) with a phase of 80-90 degrees (corresponding to 2-2.5 s at 0.1 Hz), most likely reflecting a transit time phenomenon; (2) oxy- and deoxyhemoglobin thereby oscillate in counterphase; (3) hemodynamic compromise in carotid obstruction leads to (a) delayed NIRS oscillations in comparison to BP which are highly correlated to a shorter phase lead of MCAFV against BP and (b) a decoupling of the oxy-/deoxyhemoglobin counterphase to 240 degrees . Cortical hemodynamic responses to BP oscillations follow specific phase relationships due to cerebral autoregulatory action and circulatory transit times. With hemodynamic impairment, as in unilateral carotid obstruction, these phases are significantly changed reflecting disturbed autoregulation.

The objective of the present study was to identify predictors of left atrial spontaneous echocardiographic contrast (SEC) or thrombus in patients with stroke with sinus rhythm and left ventricular dysfunction. Of 500 consecutive patients with stroke, 48 with sinus rhythm and reduced left ventricular ejection fractions (EFs)or =45% were examined. Ten patients presented with SEC or thrombus. The patients with SEC or thrombus had larger left atrial diameters (47 +/- 4 vs 42 +/- 6 mm, p0.05), smaller EFs (30 +/- 9% vs 38 +/- 8%, p0.01), and slower left atrial appendage (LAA) flow velocities (42 +/- 13 vs 61 +/- 17 cm/s, p0.01). Multivariate analysis identified EFor =35% and LAA flow velocityor =55 cm/s as predictors of SEC or thrombus (p0.05). Patients with stroke with sinus rhythm and moderate- to high-grade reduction of the left ventricular EF represent a risk group for a left atrial source of embolism and should undergo transesophageal echocardiography.

Dissection of the internal carotid artery (ICAD; Fig. 1) is not only widely accepted as an important component of stroke aetiology, it is also well recognised as a focal cause of lower cranial nerve palsy. In the present patient, a duplex ultrasound revealed a left, submandibular ICAD originating 3 cm distal to the ICA bifurcation. In parallel, a high-grade, long-distance stenosis was confirmed by a time-of-flight magnetic resonance angiogram. Axial T2-weighted MRI showed a crescent-like, hyperintense signal corresponding to an intramural haematoma. In addition, an asymptomatic dissecting vertebral artery (VA) aneurysm on the right V2-segment was