Investigation of the Properties of 316L Stainless Steel after AM and Heat Treatment.

Additive manufacturing, including laser powder bed fusion, offers possibilities for the production of materials with properties comparable to conventional technologies. The main aim of this paper is to describe the specific microstructure of 316L stainless steel prepared using additive manufacturing. The as-built state and the material after heat treatment (solution annealing at 1050 °C and 60 min soaking time, followed by artificial aging at 700 °C and 3000 min soaking time) were analyzed. A static tensile test at ambient temperature, 77 K, and 8 K was performed to evaluate the mechanical properties. The characteristics of the specific microstructure were examined using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The stainless steel 316L prepared using laser powder bed fusion consisted of a hierarchical austenitic microstructure, with a grain size of 25 µm as-built up to 35 µm after heat treatment. The grains predominantly contained fine 300-700 nm subgrains with a cellular structure. It was concluded that after the selected heat treatment there was a significant reduction in dislocations. An increase in precipitates was observed after heat treatment, from the original amount of approximately 20 nm to 150 nm.

Health Related Studyability-An Approach to Structure Health Promotion Interventions at Universities.

So far, the only existing prerequisite to enter an academic institution is a specific diploma, like a high school diploma, or another comparable certified document. Other requirements may only be a numerus clausus for certain fields of study to pave the bureaucratic way for a prospective student into their university life. The way first year students dive into their first academic experiences is entirely left to themselves. (Soft) Skills and Competences that exceed the expertise of the chosen courses but are essential for this new, and very challenging, chapter of their lives are not taught to them. Therefore, student health promotion for young adults is essential to build and sustain a healthy lifestyle during their academic careers. Nevertheless, it is important to consider not only a student's perspective but also structural and organizational conditions within the academic institutions. The further development of Ilmarinen's concept of workability may help to construct a theoretical and empirically based concept to implement health-promoting conditions for a student health promotion system at universities. Ilmarinen's concept was chosen by the work group in terms of the structure, which may be adapted to a university since it can be seen as a student's workplace.

Case Study of the Tensile Fracture Investigation of Additive Manufactured Austenitic Stainless Steels Treated at Cryogenic Conditions.

Additive manufacturing is a key enabling technology in the manufacture of highly complex shapes, having very few geometric limitations compared to traditional manufacturing processes. The present paper aims at investigating mechanical properties at cryogenic temperatures for a 316L austenitic stainless steel, due to the wide possible cryogenic applications such as liquid gas confinement or superconductors. The starting powders have been processed by laser powder bed fusion (LPBF) and tested in the as-built conditions and after stress relieving treatments. Mechanical properties at 298, 77 and 4.2 K from tensile testing are presented together with fracture surfaces investigated by field emission scanning electron microscopy. The results show that high tensile strength at cryogenic temperature is characteristic for all samples, with ultimate tensile strength as high as 1246 MPa at 4.2 K and 55% maximum total elongation at 77 K. This study can constitute a solid basis for investigating 316L components by LPBF for specific applications in cryogenic conditions.

Physical fitness and health-related quality of life in pediatric renal transplant recipients: An interventional trial with active video gaming.

BACKGROUND: Pediatric renal transplant recipients are at increased risk for cardiovascular diseases, one contributing factor is reduced cardiorespiratory fitness. The purpose was to evaluate cardiorespiratory fitness, motor coordination, muscle strength, daily physical activity, and health-related quality of life and to find out, if active video gaming is effective for improving these items in this patient population. METHODS: Twenty renal transplant recipients (13.5 ± 3.4 years) and 33 matched healthy controls (13.1 ± 3.2 years) performed a spiroergometry, a motor coordination test, and a maximal handgrip strength test. Quality of life was determined with a validated questionnaire, and daily physical activity was recorded with a physical activity monitor. Thirteen patients (12.9 ± 3.4 years) participated in a 6-week home-based exergaming intervention (3×/week for 30 minutes) and repeated all tests after that. RESULTS: The renal transplant recipients exhibited a substantial impairment compared with the controls in peak oxygen consumption (-31%, P < .001), motor competence (-44%, P < .001), daily physical activity (-33%, P = .001), and quality of life (-12%, P = .017). Handgrip strength was similar in both groups. Despite of low compliance in the intervention group, steps per hour were significantly increased after 6 weeks of exergaming (+31%, P = .043); however, all other measures remained unchanged. CONCLUSION: Cardiorespiratory fitness, motor competence, and quality of life are reduced in pediatric renal transplant recipients. Home-based exergaming is not appropriate to improve these items, probably due to a substantially impaired motor competence. However, it provided a stimulus for an increased daily physical activity.

Aquatic toxicity of the macrolide antibiotic clarithromycin and its metabolites.

The human macrolide antibiotic clarithromycin is widespread in surface waters. Our study shows that its major metabolite 14-hydroxy(R)-clarithromycin is found in surface waters in comparable amounts. This metabolite is known to be pharmacologically active. Additionally, clarithromycin is partly metabolised to N-desmethyl-clarithromycin, which has no antimicrobial activity. For clarithromycin, some ecotoxicological studies on aquatic organisms have been published. However, many of them are not conform with the scientific principles as given in the "Technical guidance for deriving environmental quality standards" (TGD-EQS), because numerous studies were poorly documented and the methods did not contain analytical measurements confirming that the exposure concentrations were in the range of ± 20% of the nominal concentrations. Ecotoxicological effects of clarithromycin and its two metabolites on the zebrafish Danio rerio (embryo test), the microcrustacean Daphnia magna, the aquatic monocotyledonous macrophyte Lemna minor, the freshwater green alga Desmodesmus subspicatus (Chlorophyta) and the cyanobacterium Anabaena flosaquae were investigated in compliance with the TGD-EQS. Environmental risk assessment was performed using ErC10 values of Anabaena, the species most sensitive to clarithromycin and 14-hydroxy(R)-clarithromycin in our testing. Based oncomparable toxicity and similar concentrations of clarithromycin and its active metabolite 14-hydroxy(R)-clarithromycin in surface waters, an additional multiplication factor of 2 to the assessment factor of 10 on the ErC10 of clarithromycin should be used. Consequently, a freshwater quality standard of 0.130 µg L(-1) is proposed for clarithromycin as the "lead substance". Taking this additional multiplication factor of 2 into account, single monitoring of clarithromycin may be sufficient, in order to reduce the number of substances listed for routine monitoring programs.

Behavior of sartans (antihypertensive drugs) in wastewater treatment plants, their occurrence and risk for the aquatic environment.

Pharmaceuticals and other anthropogenic trace contaminants reach wastewaters and are often not satisfactorily eliminated in sewage treatment plants. These contaminants and/or their degradation products may reach surface waters, thus influencing aquatic life. In this study, the behavior of five different antihypertonic pharmaceuticals from the sartan group (candesartan, eprosartan, irbesartan, olmesartan and valsartan) is investigated in lab-scale sewage plants. The elimination of the substances with related structures varied broadly from 17 % for olmesartan up to 96 % for valsartan. Monitoring data for these drugs in wastewater effluents of six different sewage treatment plants (STPs) in Bavaria, and at eight rivers, showed median concentrations for, e.g. valsartan of 1.1 and 0.13 µg L(-1), respectively. Predicted environmental concentrations (PEC) were calculated and are mostly consistent with the measured environmental concentrations (MEC). The selected sartans and the mixture of the five sartans showed no ecotoxic effects on aquatic organisms in relevant concentrations. Nevertheless, the occurrence of pharmaceuticals in the environment should be reduced to minimize the risk of their distribution in surface waters, ground waters and bank filtrates used for drinking water.

Occurrence and fate of the human pharmaceutical metabolite ritalinic acid in the aquatic system.

To investigate the occurrence and fate of ritalinic acid - the main human metabolite of the psychostimulant drug methylphenidate - in the aquatic environment, a HPLC-electrospray-MS/MS method for the quantification of ritalinic acid in wastewater, surface water and bank filtrate was developed. Carbamazepine known as very stable in the aquatic environment was analyzed as anthropogenic marker in parallel. Furthermore, the removal of ritalinic acid was studied in a sewage treatment plant using an activated sludge system during a field study and in lab-scale plants. In good agreement between lab-scale and field studies a low removal rate of 13% and 23%, respectively, was determined. As a consequence, the concentration of ritalinic acid in the wastewater effluents were in the range of <50-170 ngL(-1) which corresponds to a mean specific load per capita of 17.7 µgd(-1). Ritalinic acid has further been detected in German rivers at concentrations of 4-23 ngL(-1) and in bank filtrate samples in 100-850 m distance from the river up to 5 ngL(-1) demonstrating the widespread occurrence of this stable metabolite in the aquatic environment. A comparison to available sales data shows that a significant amount of methylphenidate applied can be found in waters as ritalinic acid.

Sulfamethazine and flubendazole in seepage water after the sprinkling of manured areas.

Pharmaceuticals are widely used in modern livestock production and can reach the environment via the application of manure containing excreted drugs. Limited information is available on the transport and fate of veterinary medicines applied to soils. Therefore, we assessed the potential for the sulphonamide antibiotic sulfamethazine (SMT) and the antiparasitic drug flubendazole (FLUB) including their metabolites to move from agricultural manure to drainage waters at 1m depth. A comparison was made of losses from sites under different land use (grassland versus arable cropping) as well as losses from neighbouring plots under the same land use. Liquid manure from pigs treated with SMT and FLUB was spread on 10 x 30 m2 plots (750l per plot). SMT concentration in slurry ranged from 600 to 1700 microg l(-1) (metabolite acetyl-SMT 280-1700 microg l(-1)) and FLUB concentration ranging from 25 to 56 microg l(-1) (metabolite amino-FLUB 32-110 microg l(-1), hydroxy-FLUB 19-38 microg l(-1)). About 1h after application heavy rainfall (50mm in 2.5h) was simulated by sprinkler irrigation. Drainage flow started within 1h after the commencement of sprinkling. SMT and FLUB concentrations in leachate reached values of up to 16 microg l(-1) and 0.3 microg l(-1), respectively. Loss rates (relative to the applied amounts) from the neighbouring sites under arable cropping ranged from 2.8% to 5.4% for SMT and 0.8% to 3.1% for FLUB (including metabolites). On the permanent grassland plot, due to its multitude of macropores, loss rates reached values up to 10% for SMT and 16% for FLUB (including metabolites). These results demonstrate that the variability in leaching of veterinary drugs may be high even between large neighbouring plots, depending on site heterogeneity and land use.