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28 result(s) for "Drossel, Thomas"
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Dynamic formation of a solid-liquid electrolyte interphase and its consequences for hybrid-battery concepts
The discharging and charging of batteries require ion transfer across phase boundaries. In conventional lithium-ion batteries, Li + ions have to cross the liquid electrolyte and only need to pass the electrode interfaces. Future high-energy batteries may need to work as hybrids, and so serially combine a liquid electrolyte and a solid electrolyte to suppress unwanted redox shuttles. This adds new interfaces that might significantly decrease the cycling-rate capability. Here we show that the interface between a typical fast-ion-conducting solid electrolyte and a conventional liquid electrolyte is chemically unstable and forms a resistive solid-liquid electrolyte interphase (SLEI). Insights into the kinetics of this new type of interphase are obtained by impedance studies of a two-chamber cell. The chemistry of the SLEI, its growth with time and the influence of water impurities are examined by state-of-the-art surface analysis and depth profiling. Li + -selective solid electrolytes may enable next-generation battery systems, such as Li–S and Li–O 2 . Now, in an exemplar system, it is shown that a resistive interphase forms at the interface between solid and liquid electrolytes, termed the solid-liquid electrolyte interphase (SLEI). An in situ study of this undesirable effect is supported by state-of-the-art surface analysis.
Printed Multilayer Piezoelectric Transducers on Paper for Haptic Feedback and Dual Touch-Sound Sensation
With a growing number of electronic devices surrounding our daily life, it becomes increasingly important to create solutions for clear and simple communication and interaction at the human machine interface (HMI). Haptic feedback solutions play an important role as they give a clear direct link and response to the user. This work demonstrates multifunctional haptic feedback devices based on fully printed piezoelectric transducers realized with functional polymers on thin paper substrate. The devices are flexible; lightweight and show very high out-of-plane deflection of 213 µm at a moderate driving voltage of 50 Vrms (root mean square) achieved by an innovative multilayer design with up to five individually controllable active layers. The device creates a very clear haptic sensation to the human skin with a blocking force of 0.6 N at the resonance frequency of 320 Hz, which is located in the most sensitive range of the human fingertip. Additionally the transducer generates audible information above two kilohertz with a remarkable high sound pressure level. Thus the paper-based approach can be used for interactive displays in combination with touch sensation; sound and color prints. The work gives insights into the manufacturing process; the electrical characteristics; and an in-depth analysis of the 3D deflection of the device under variable conditions
Optimization of thick sheet clinching tools using principal component analysis
A new optimization method based on the principal component analysis (PCA) is presented for the identification of geometry parameters in tool design for mechanical clinching process of thick sheets. By applying PCA in joining, numerous dependent variables relevant for quality can be approximated with a very low number of statistical eigenmodes. Subsequently, the eigenmodes are used instead of the actual dependent variable for mathematically characterising the entire joint. This method offers the possibility of forming a direct functional relation between the tool parameters and the adherend geometries. Thus, the quality of a joint can be optimized by a generic algorithm (GA).
Factors determining the quality of screening colonoscopy: a prospective study on adenoma detection rates, from 12 134 examinations (Berlin colonoscopy project 3, BECOP-3)
Background Screening colonoscopy (SC) outcome quality is best determined by the adenoma detection rate (ADR). The substantial variability in the ADRs between endoscopists may reflect different skills, experience and/or equipment. Objective To analyse the potential factors that may influence ADR variance, including case volume. Design 12 134 consecutive SCs (mean age 64.5 years, 47% men) from 21 Berlin private-practice colonoscopists were prospectively studied during 18 months. The data were analysed using a two-level mixed linear model to adequately address the characteristics of patients and colonoscopists. The ADR was regressed after considering the following factors: sex, age, bowel cleanliness, NSAID intake, annual SC case volume, lifetime experience, instrument withdrawal times, instrument generations used, and the number of annual continuing medical education (CME) meetings attended by the physician. The case volume was also retrospectively analysed from the 2007 national SC registry data (312 903 colonoscopies and 1004 colonoscopists). Results The patient factors that correlated with the ADR were sex, age (p<0.001) and low quality of bowel preparation (p=0.005). The factors that were related to the colonoscopists were the number of CME meetings attended (p=0.012) and instrument generation (p=0.001); these factors accounted for approximately 40% of the interphysician variability. Within a narrow range (6–11 min), the withdrawal time was not correlated with the ADR. Annual screening case volume did not correlate with the ADR, and this finding was confirmed by the German registry data. Conclusions The outcome quality of screening colonoscopies is mainly influenced by individual colonoscopist factors (ie, CME activities) and instrument quality. Clinical trial registration number Clinical Trial Gov Registration number: NCT00860665.
Proof of Concept for the Detection of Local Pressure Marks in Prosthesis Sockets Using Structural Dynamics Measurement
The wear comfort of a prosthesis is of great importance for amputee patients. The wear comfort can be affected by changes in the interface between the residual limb and prosthesis socket, which can be caused by time-dependent volume fluctuations of the tissue, leading to unwanted local pressure marks. The basis to ensure time-independent wear comfort of a prosthesis is to identify these changes. Common techniques for identifying these variations have a negative impact on the sensitive interface between the residual limb and prosthesis. The following paper contains a proof of concept for the detection of local pressure marks without affecting the described interface using structural dynamics measurements, exemplarily shown at a prosthetic socket for transfemoral amputees in a test bench scenario. The dynamical behaviour of the investigated system is analysed in the form of frequency response functions acquired for different pressure locations and preloads using an impact hammer for excitation and a triaxial acceleration sensor. The frequency response functions show major changes for the various boundary conditions with respect to their frequency-dependent compositions. The results demonstrate how the utilised method enables the identification of changes in local pressure marks regarding the variation of position and magnitude.
ADAPTING DIALECTICAL BEHAVIOR THERAPY TO ADDRESS CAREGIVER HEALTH IN HIGH-CONFLICT CAREGIVING SITUATIONS
Family caregivers of older adults with neurocognitive disorders (NCDs) are invisible patients in the U.S. healthcare system. This is especially concerning because poor caregiver mental or physical health predicts coercive care practices (e.g., yelling or threatening the older adult). When older adults with NCD come to providers’ attention for emotional and behavioral changes, systematic strategies for assessing and intervening on caregiver health and potential coercive caregiving patterns are lacking. The present study consisted of a retrospective chart review of clinical records from family caregivers who participated in dialectical behavior therapy (DBT) skills training groups adapted for high-conflict situations involving older adults with NCDs (Drossel, Fisher, & Mercer, 2011) in a doctoral-level psychology training clinic in the Midwest. Data from 32 family caregivers enrolled across eight 8-week DBT groups showed that caregivers whose medical records indicated significant health problems tended to describe themselves as healthy when completing the RAND 36-Item Health Survey (SF-36; Hayes et al., 1993). Attrition from the groups was mainly due to acute medical crises, and caregivers required significant individual support to address their medical concerns, prompting modifications to the DBT mindfulness and interpersonal effectiveness modules (e.g., developing DEAR MAN scripts to delegate care tasks to third-party providers). These findings suggest the need for routine, systematic, and direct assessments of caregiver health and skills-based approaches targeting health promotion and disease prevention to address coercive caregiving practices.
Mechanical and Microstructural Characterization of Ultrasonic Welded NiTiCu Shape Memory Alloy Wires to Silver-Coated Copper Ferrules
The aim of this study was to investigate the mechanical behavior, and the microstructure of NiTiCu shape memory alloy wires joined with silver-coated copper ferrules via ultrasonic spot welding. Therefore, the electrical resistance was measured during tensile testing, and the joints were analyzed by scanning electron microscopy. Energy-dispersive X-ray spectroscopy has determined the compounds of the developed welding zones. Furthermore, the influence of the ultrasonic welding on the transition temperatures of the NiTiCu wires was examined via differential scanning calorimetry. Tensile tests have shown that the ultimate tensile strengths of the joints reached almost 100% of that of the base material. An additional heat treatment rebuilt the typical shape memory alloy behavior after the ultrasonic welding process detwinned the martensitic wires. In addition, the B19′ structure of the welding zone and the ultrasonic spot-welding process did not affect the transition temperatures of the shape memory alloy.
Endoscopic versus histological characterisation of polyps during screening colonoscopy
Background As screening colonoscopy becomes more widespread, the costs for histopathological assessment of resected polyps are rising correspondingly. Reference centres have published highly accurate results for endoscopic polyp classification. Therefore, it has been proposed that, for smaller polyps, the differential diagnosis that guides follow-up recommendations could be based on endoscopy alone. Objective The aim was to prospectively assess whether the high accuracy for endoscopic polyp diagnosis as reported by reference centres can be reproduced in routine screening colonoscopy. Design Ten experienced private practice endoscopists had initial training in pit patterns. Then they assessed all polyps detected during 1069 screening colonoscopies. Patients (46% men; mean age 63 years) were randomly assigned to colonoscopy with conventional or latest generation HDTV instruments. The main outcome measure was diagnostic accuracy of in vivo polyp assessment (adenomatous vs hyperplastic). Secondary outcome measures were differences between endoscopes and reliability of image-based follow-up recommendations; a blinded post hoc analysis of polyp photographs was also performed. Results 675 polyps were assessed (461 adenomatous, 214 hyperplastic). Accuracy, sensitivity and specificity of in vivo diagnoses were 76.6%, 78.1% and 73.4%; size of adenomas and endoscope withdrawal time significantly influenced accuracy. Image-based recommendations for post-polypectomy surveillance were correct in only 69.5% of cases. Post hoc analysis of polyp photographs did not improve accuracy. Conclusions In everyday practice, endoscopic classification of polyp type is not accurate enough to abandon histopathological assessment and use of latest generation colonoscopes does not improve this. Image-based surveillance recommendations after polypectomy would consequently not meet guideline requirements. TrialRegNoNCT01297712.
Live Image Processing Does Not Increase Adenoma Detection Rate During Colonoscopy: A Randomized Comparison Between FICE and Conventional Imaging (Berlin Colonoscopy Project 5, BECOP-5)
Fujinon intelligent chromoendoscopy (FICE) is a post-processing imaging technique for increasing contrast of mucosa and mucosal lesions that might lead to improvement in colonic adenoma detection during colonoscopy. Previous studies on similar contrast-enhancing techniques as well as on dye staining have yielded variable and conflicting results. This large randomized trial was undertaken to determine whether FICE technology enhances adenoma detection rate (ADR). In a prospective study performed in a multicenter private practice and hospital setting, involving 8 examiners with substantial lifetime experience (>10,000 colonoscopies each), 1,318 patients (men 46.7%, women 53.3%; mean age 59.05 years) were randomly assigned to colonoscopy with either FICE or white light imaging on instrument withdrawal. Of the colonoscopies, 68% were screening and 32% were diagnostic examinations. The primary outcome measure was the ADR (i.e., number of adenomas/total number of patients). There was no difference between the two groups in terms of general ADR (0.28 in both groups), the total number of adenomas (184 vs. 183), or detection of subgroups of adenomas. The rate of identification of hyperplastic polyps was also the same in both groups (127 vs. 121; P=0.67). The results were the same for both the screening and the diagnostic colonoscopy subgroups. Withdrawal time was the same in both groups (8.4 vs. 8.3 min, P=0.55). This large randomized trial could not show any objective advantage of the FICE technique over conventional high-resolution endoscopy in terms of improved ADR.
Advanced Material Studies for Additive Manufacturing in terms of Future Gear Application
Additive manufacturing by laser beam melting is predestined for complex component geometry like integrated cooling channels without enormous posttreatment processing. To investigate the influence of build-up direction in terms of later tooth excitation of gear-wheels, first fundamental material analyses were accomplished in this publication. Therefore, additively produced specimens were used to determine the build-up direction dependent elastic properties of the material in all three spatial directions based on tensile and torsion tests. The anisotropies of elastic limits and breaking points of previous studies were confirmed in this paper. Furthermore, torsion values were also determined depending on build-up direction. Laser beam melted X3NiCoMoTi18-9-5 (hot-work tool steel) was shown to exhibit extremely high performance under shear loading in comparison to conventionally processed steel. The influence of build-up direction on torsional strength was also shown.