Cyclic behavior and microstructural stability of ultrafine-grained AA6060 under strain-controlled fatigue

AbstractThe strain-controlled fatigue behavior of AA6060, a precipitation hardening aluminum alloy, was investigated in ultrafinegrained (UFG) conditions after severe plastic deformation (SPD) by equal-channel angular pressing (ECAP). Two as-processed conditions, representing different stages of strain hardening and grain refinement as well as a ductility-optimized condition, achieved by a combined ECAP and aging treatment were considered. Low-voltage scanning transmission electron microscopy on samples stopped at characteristic stages of the fatigue process was applied to investigate the microstructural development. The as-processed as well as the optimized condition showed cyclic softening, which was found to be dependent on the amount of prestrain induced by ECAP processing. This is linked to dynamic recovery processes in the microstructure, indicated by a clearer distinction of grain boundaries and a reduction of dislocations in the grain interior. For all applied plastic strain amplitudes, ranging from Δεpl/2=1×10−3 to 5×10−3, the fatigue life of the ductility-optimized condition did not reach that of the severely work-hardened counterpart. For explaining this unexpected result, the differing (size-dependent) effectiveness of precipitates for the pinning of dislocations during cyclic loading was considered

Effect of Ram and Zenith Exposure on the Optical Properties of Polymers in Space

The temperature of spacecraft is influenced by the solar absorptance and thermal emittance of the external spacecraft materials. Optical and thermal properties can degrade over time in the harsh low Earth orbital (LEO) space environment where spacecraft external materials are exposed to various forms of radiation, thermal cycling, and atomic oxygen. Therefore, it is important to test the durability of spacecraft materials in the space environment. One objective of the Polymers and Zenith Polymers Experiments was to determine the effect of LEO space exposure on the optical properties of various spacecraft polymers. These experiments were flown as part of the Materials International Space Station Experiment 7 (MISSE 7) mission on the exterior of the International Space Station (ISS) for 1.5 years. Samples were flown in ram, wake or zenith directions, receiving varying amounts of atomic oxygen and solar radiation exposure. Total and diffuse reflectance and transmittance of flight and corresponding control samples were obtained post-flight using a Cary 5000 UV-Vis-NIR Spectrophotometer. Integrated air mass zero solar absorptance (s) of the flight and control samples were computed from the total transmittance and reflectance, and compared. The optical data are compared with similar polymers exposed to space for four years as part of MISSE 2, and with atomic oxygen erosion data, to help understand the degradation of these polymers in the space environment. Results show that prolonged space exposure increases the solar absorptance of some materials. Knowing which polymers remain stable will benefit future spacecraft design

Using mixed methods for analysing culture : The Cultural Capital and Social Exclusion project

This paper discusses the use of material generated in a mixed method investigation into cultural tastes and practices, conducted in Britain from 2003 to 2006, which employed a survey, focus groups and household interviews. The study analysed the patterning of cultural life across a number of fields, enhancing the empirical and methodological template provided by Bourdieu’s Distinction. Here we discuss criticisms of Bourdieu emerging from subsequent studies of class, culture and taste, outline the arguments related to the use of mixed methods and present illustrative results from the analysis of these different types of data. We discuss how the combination of quantitative and qualitative methods informed our analysis of cultural life in contemporary Britain. No single method was able to shed light on all aspects of our inquiry, lending support to the view that mixing methods is the most productive strategy for the investigation of complex social phenomena

The new onset of dysphagia four years after anterior cervical discectomy and fusion: Case report and literature review.

Background: Dysphagia is a common complication immediately following anterior cervical spine surgery. However, its onset more than 1-year postoperatively is rare. Case Description: A 45-year-old male initially underwent a C3-4 and C5-6 anterior cervical discectomy and fusion (ACDF). At age 49, 4 years later, he presented with worsening dysphagia accompanied by neck and right upper extremity pain. Radiographs demonstrated an extruded left C3 screw, which had migrated into the prevertebral soft tissues at the C4-C5 level; there was also loosening of the right C3 screw. The subsequent barium swallow study revealed that the screw was embedded in the pharyngeal wall. The patient required a two-stage operation; first, to remove the anterior instrumentation, and second, to perform a posterior instrumented C2-T2 fusion. Conclusion: A barium swallow study and other dynamic imaging are a valuable component of the diagnostic workup and therapeutic intervention to evaluate the delayed onset dysphagia following an ACDF

Leindotterpresskuchen in ökologischen Futterrationen: Stand der Forschung

Organic farming needs home-grown energy and protein sources in livestock feeding. Due to the concept of mixed cropping systems with oilseeds like false flax (Camelina sativa (L.) Crantz) the possible use of its oilcake as a component of feeding rations is attracting attention of farmers. False flax is an undesired substance in the European rules on feeding stuffs and the use of its oilcake in animal feeding is subject of diverse research projects. A review of the recentThe experiences shows that the use of oilcake of false flax in monogastric animals can negatively affect sensory meat quality and metabolism obvious in enlarged organs. In ruminant feeding those effects are not observed. Further research is needed to find out adopted feeding rations for different livestock. In dairy feeding additional experiments on the effect on milk fat contents should confirm existing results

The role of co-morbidity in the selection of antidiabetic pharmacotherapy in type-2 diabetes

Metformin is, if not contraindicated and if tolerated, usually preferred over other antidiabetic drugs for the first line treatment of type-2 diabetes. The particular decision on which antidiabetic agent to use is based on variables such as efficacy, cost, potential side effects, effects on weight, comorbidities, hypoglycemia, risk, and patient preferences. However, there is no guidance how to consider these in the selection of antidiabetic drug treatment. In this work, we aimed to summarize available evidence and tried to give pragmatic treatment recommendations from a clinical practice perspective. There are clear contraindications for some drugs in those with impaired renal and liver function and precautions in those with heart failure for the use of metformin (NYHA III-IV) and glitazones. On the other hand, GLP-1 analogs, DPP-4 inhibitors and acarbose are generally less critical and can be used in the majority of patients. We identified the following gaps with respect to the selection of antidiabetic drug treatment in patients with co-morbid disease conditions: 1) Guidelines fail to give advice on the use of specific antidiabetic drugs in patients with co-morbidity. 2) The literature is deficient in studies documenting antidiabetic drug use in patients with severely impaired renal function, diabetic retinopathy, cerebrovascular disease and systolic heart failure. 3) Further there are no specific data on patients with multiple of these co-morbid disease conditions. We postulate that differential use of antidiabetic drugs in patients with co-morbid disease constellations will help to reduce treatment related complications and might improve prognosis

Benefits of sexual practice during pregnancy: myth or reality? Comparative study and outcome of childbirth in Douala (Cameroon)

Background: Pregnancy is the term used to describe the period in which a foetus develops in the uterus and lasts 40 weeks measured from the last menstrual period. Anatomic and physiologic changes in pregnant women usually make couples to change their emotional and sexual activities that may impact childbirth. There are few studies in our setting that describe the roles of sexual practice during pregnancy and maternal-foetal outcomes of childbirth.Objective of this study aimed at assessing the benefits of sexual practice during pregnancy in a target population and to assess the outcome.Methods: We carried out a comparative cross-sectional study from February 2018 to May 2018, at the maternity of Laquintinie Hospital in Douala. Socio-demographic, obstetric, sexual history in pregnancy, birth and neonatal data were collected using a structured questionnaire. Univariate and multivariate analyses were conducted at a 95% confidence interval.Results: A total of 300 respondents completed study and 69.6% were favourable to sexual intercourse during pregnancy. Induction or augmentation of labour was common in the unfavourable group [OR: 2.52 (1.53-4.15); p=0.004]. Almost one in two participants gave birth by caesarean section and the indications for caesarean section were similar in both groups. Participants without sexual intercourse in pregnancy had a 9-fold increased risk of perineal tears [OR: 8.99 (4.02-10.1); p=0.001] and 5.4-fold risk of cervical tears [OR: 5.44 (2.44-8.73); p=0.0001].Conclusions: Sexual practice in pregnancy appears to be protective against excessive use of oxytocin, perineal and cervical tears

Aspect ratio of nano/microstructures determines Staphylococcus aureus adhesion on PET and titanium surfaces

Aims: Joint infections cause premature implant failure. The avoidance of bacterial colonization of implant materials by modification of the material surface is therefore the focus of current research. In this in vitro study the complex interaction of periodic structures on PET and titanium surfaces on the adhesion of Staphylococcus aureus is analysed. Methods and Results: Using direct laser interference patterning as well as roll-to-roll hot embossing methods, structured periodic textures of different spatial distance were produced on surfaces and S. aureus were cultured for 24 h on these. The amount of adhering bacteria was quantified using fluorescence microscopy and the local adhesion behaviour was investigated using scanning electron microscopy. For PET structures, minimal bacterial adhesion was identified for an aspect ratio of about 0·02. On titanium structures, S. aureus adhesion was significantly decreased for profile heights of < 200 nm. Our results show a significantly decreased bacterial adhesion for structures with an aspect ratio range of 0·02 to 0·05. Conclusions: We show that structuring on surfaces can decrease the amount of S. aureus on titanium and PET as common implant materials. Significance and Impact of the Study: The study highlights the immense potential of applying specific structures to implant materials to prevent implant colonization with pathogen bacteria.Fil: Meinshausen, A. K.. Otto-von-Guericke-Universität Magdeburg; AlemaniaFil: Herbster, M.. Otto-von-Guericke-Universität Magdeburg; AlemaniaFil: Zwahr, C.. Technische Universität Dresden; AlemaniaFil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Müller, A.. Otto-von-Guericke-Universität Magdeburg; AlemaniaFil: Halle, T.. Otto-von-Guericke-Universität Magdeburg; AlemaniaFil: Lasagni, A. F.. Technische Universität Dresden; AlemaniaFil: Bertrand, J.. Otto-von-Guericke-Universität Magdeburg; Alemani