Review on the phosphate-based conversion coatings of magnesium and its alloys

Magnesium(Mg)and its alloys are lightweight as well as biocompatible and possess a high strength-to-weight ratio,making them suitable for many industries,including aerospace,automobile,and medical.The major challenge is their high susceptibility to corrosion,thereby limiting their usability.The considerably lower reduction potential of Mg compared to other metals makes it vulnerable to galvanic coupling.The oxide layer on Mg offers little corrosion resistance because of its high porosity,inhomogeneity,and fragility.Chemical conversion coatings(CCs)belong to a distinct class because of underlying chemical reactions,which are fundamentally different from other types of coating.Typically,a CC acts as an intermediate sandwich layer between the base metal and an aesthetic paint.Although chromate CCs offer superior performance compared to phosphate CCs,yet still they release carcinogenic hexavalent chromium ions(Cr^(6+));therefore,their use is prohibited in most European nations under the Registration,Evaluation,Authorization and Restriction of Chemicals legislation framework.Phosphate-based CCs are a cost-effective and environment-friendly alternative.Accordingly,this review primarily focuses on different types of phosphate-based CCs,such as zinc,calcium,Mg,vanadium,manganese,and permanganate.It discusses their mechanisms,current status,pretreatment practices,and the influence of various parameters-such as pH,temperature,immersion time,and bath composition-on the coating performance.Some challenges associated with phosphate CCs and future research directions are also elaborated.

Changes of Cardiac Biomarkers after High-intensity Exercise in Male and Female Elite Athletes of Dragon Boating

Abstract： This study investigated the effects of three sport-specific high-intensity training units on cardiac biomarker alteration in elite athletes of dragon boating. Thirty six male （age 33 ± 9） and twenty nine female （age 31 ±8） elite athletes, members of the German national team, were examined in their final training camp preparing for world championship. At two time points blood panels （pre-training and one hour post-training） were collected and concentrations of high sensitive troponin T, N-terminal pro brain natriuretic peptide （NT-pro BNP）, ereatine phosphokinase （CPK）, MB-creatine kinase （CKMB） and myoglobin were assessed. After exercise, serum levels ofNT-pro BNP, CPK, myoglobin and CKMB increased significantly （P 〈 0.01 for each） with only few values exceeding the upper reference limits. High sensitive troponin T remained below the limit of detection both before and after exercise in all athletes. Significant gender-related differences were found with a higher increase ofNT-pro BNP levels in female athletes （P 〈 0.01） compared to males. In contrast, male athletes displayed a significant higher increase of CPK （P 〈 0.01） and myoglobin （P 〈 0.01） compared to female athletes. In conclusion, three high-intensity training units did not lead to elevated high sensitive troponin T concentrations in elite athletes of dragon boating but to significant increases ofNT-pro BNP, CPK and myoglobin levels. This suggests that high-intensity training units do not lead to a cardiac injury in these athletes.

Diatom-inspired Plastic Deformation Elements for Energy Absorption in Automobiles

We report on a biomimetic approach for the construction of a deformation element in vehicles which absorbs energy in the case of lateral collisions. We aim at simultaneously maximising the energy absorption capacity of the component and mini- mising its weight. The examined deformation element, a crash-pad is inspired by the structure of a diatom which is known for its structural stability. As the natural counterpart, our crash pad is characterized by an undulated shape. The three undulations of the crash pad are of different height and provide for a sequential absorption of the impact energy. Compression tests were performed on the prototypes of the crash pad that were produced from different materials, namely a conventional talc reinforced poly- propylene and a natural fibre reinforced plastic. Compression tests revealed that the bioinspired crash pads performed better or equal than their technical counterpart. As required, the bioinspired components deformed continuously with the increase in deformation force. Since the differences in the properties of the used materials were small, the increased energy absorption properties were predominantly due to the structure of the biomimetic deformation element.