Material Extrusion of Structural Polymer–Aluminum Joints—Examining Shear Strength,Wetting, Polymer Melt Rheology and Aging

Generating polymer–metal structures by means of additive manufacturing offers huge potential for customized, sustainable and lightweight solutions. However, challenges exist, primarily with regard to reliability and reproducibility of the additively generated joints. In this study, the polymers ABS, PETG and PLA, which are common in material extrusion, were joined to grit-blasted aluminum substrates. Temperature dependence of polymer melt rheology, wetting and tensile single-lap-shear strength were examined in order to obtain appropriate thermal processing conditions. Joints with high adhesive strength in the fresh state were aged for up to 100 days in two different moderate environments. For the given conditions, PETG was most suitable for generating structural joints. Contrary to PETG, ABS–aluminum joints in the fresh state as well as PLA–aluminum joints in the aged state did not meet the demands of a structural joint. For the considered polymers and processing conditions, this study implies that the suitability of a polymer and a thermal processing condition to form a polymer–aluminum joint by material extrusion can be evaluated based on the polymer’s rheological properties. Moreover, wetting experiments improved estimation of the resulting tensile single-lap-shear strength.     

氯仿重结晶棉酚的质量研究

报道了氯仿重结晶的棉酚的化学性质,样品在不同温度下干燥恒重后,经熔点、薄层层析、紫外光谱、红外光谱、X-射线衍射、热重量分析、元素(C,H,Cl)分析及棉酚合量测定等一系列的分析,确证了在60℃以下棉酚与氯仿成溶剂化物(solvate)。随着干燥温度的升高或在室温长时间的贮存,此现象逐渐消失,100℃真空干燥恒重后成为纯棉酚。     

Tubulin polymerization‐promoting protein family member 3, Tppp3, is a specific marker of the differentiating tendon sheath and synovial joints

Tppp3, a member of the Tubulin polymerization‐promoting protein family, is an intrinsically unstructured protein that induces tubulin polymerization. We show that Tppp3 is a distinct marker in the developing musculoskeletal system. In tendons, Tppp3 is expressed in cells at the circumference of the developing tendons, likely the progenitors of connective tissues that surround tendons: the tendon sheath, epitenon, and paratenon. These tissues form an elastic sleeve around tendons and provide lubrication to minimize friction between tendons and surrounding tissues. Tppp3 is the first molecular marker of the tendon sheath, opening the door for direct examination of these tissues. Tppp3 is also expressed in forming synovial joints. The onset of Tppp3 expression in joints coincides with cavitation, representing a molecular marker that can be used to indicate this stage in joint transition in joint differentiation. In late embryonic stages, Tppp3 expression highlights other demarcation lines that surround differentiating tissues in the forelimb. Developmental Dynamics 238:685–692, 2009. © 2009 Wiley‐Liss, Inc.     

A history of atrial fibrillation

Vulpian in France and Hoff and Ludwing in Germany first studied atrial fibrillation in experimental animals. In clinical medicine, de Senac and others, first observed irregular and fast pulse. Hering in 1903 described "pulsus irregularis perpetuus" as a distinct arrhythmia. Hering believed, that this was an extrasystolic rhythm disturbance, while Cushny and Edmunds suggested atrial fibrillation as its cause. Mackenzie was another British author who played an important role in the clarification of atrial fibrillation, particularly after Cushny convinced him, that the so-called nodal rhythm was atrial fibrillation. Einthoven reported the first ECG of atrial fibrillation without recognizing its true nature. Finally in 1909 and 1910 Lewis in London and, Rothberger and Winterberg in Vienna established atrial fibrillation as a clinical entity.     

Carotid sinus massage. Its diagnostic and therapeutic value in arrhythmias

Carotid sinus massage is a simple bedside maneuver that helps to clarify the type and sometimes also the mechanism of different rhythm disturbances. The major indication for carotid sinus massage is the diagnosis of tachyarrhythmias in which the atrial activity is either absent or intermittently present. Carotid sinus massage is also useful in some patients with normal heart rates; increased vagal tone may normalize a bundle branch block or localize the site of type I second-degree atrioventricular block and can be used for evaluation of the sensing function of permanent pacemakers. Carotid sinus massage is also an important diagnostic procedure in patients with suspected hypersensitivity of the carotid sinus. Massage of the carotid sinus is contraindicated in patients with diseased carotid arteries because of the risk of cerebrovascular accident. In rare instances, carotid sinus massage may initiate ventricular tachycardia.     

Serum-sickness-like illness as a complication after streptokinase therapy for acute myocardial infarction

We report a case of serum-sickness-like illness in a 47-year-old patient who received early high-dose intravenous and intracoronary streptokinase following acute myocardial infarction. The picture comprised severe arthralgias, fever, an urticarial rash and marked elevation of circulating immune complexes. This case represents a rare complication of streptokinase therapy.     

Influence of data filtering on reliability of respiratory impedance and derived parameters in children

Forced oscillation impedance (Zrs) measurements are frequently corrupted by noisy data in children. Our aim was to improve the reliability of respiratory resistance (Rrs) and routine identification of its flow (V') and volume (V) dependence during tidal breathing, according to Rrs = K1 + K2 x /V'/ + K3 x V. Zrs was measured at 12 Hz, using a head generator in 23 children aged 4-13 years undergoing methacholine (Mch) challenge. Rrs, K1, K2, K3, and residual mean square error (RMSD), as well as reproducibility of the parameters, were obtained. Calculations were performed separately in inspiration and expiration on the raw data, and after eliminating values lying outside confidence intervals ranging from 99% (F3SD) to 95% (F2SD) of the mean Zrs. Filtering decreased RMSD and Rrs, F3SD improved reproducibility of Rrs in expiration compared to raw data. F2SD increased K1 and decreased the amplitude of K2 and K3 before and after Mch compared to F3SD. Rrs and K2 were significantly larger and K3 significantly more negative in expiration than in inspiration at all levels of filtering, probably because of the upper airways. F3SD appeared efficient in eliminating aberrant data, while allowing the identification of physiological variations of Rrs.