Effect of microstructure on corrosion resistance and anodising behaviour of AA 2099-T8 aluminium alloy

The effect of microstructure on corrosion resistance and anodising behaviour of a 3rd generation lithium-containing aluminium alloy, AA 2099-T8, has been studied. Microstructural characterisation of the alloy has shown elongated grains with high angle grain boundaries and approximately equiaxed subgrains with low angle grain boundaries. Two types of constituent particles of high and reduced contents of copper were found, which are present individually or in the form of multiphase particles. The alloy also contains rod-like Al-Cu-Mn-Li and spherical (Al3Zr) dispersoids, and fine age hardening precipitates of T1 (Al2CuLi), (Al3Li) and (Al2Cu).Immersion testing in a chloride-containing solution revealed two types of localised corrosion sites: one was initiated from intermetallics and quickly became passivated; the other lasted for the course of testing, with extensive boundary attack. The latter has been correlated to grains and subgrains with relatively high stored energy.Alkaline etching removed intermetallics from alloy surface; generated a copper-enriched layer in the alloy matrix immediately beneath the residual alumina film; and gradually developed a surface nanotexture. The surface nanotexture has been correlated to the formation of copper-rich nanoparticles within the copper-enriched layer.Anodising the alloy in tartaric-sulphuric acid disclosed that copper in the alloy matrix could be occluded in the anodic film material as copper-rich nanoparticles or be oxidized and incorporated into the film material as copper ions, depending on the anodising voltage. In the latter case, the process was accompanied by oxygen gas generation within the film material, forming anodic films with lateral porosity. Intermetallics of different compositions behaved differently during anodising, leading to modification of the morphology and composition of anodic films. Concerning the effect of alkaline etching on anodising behaviour of the alloy, the removal of intermetallics increased anodising efficiency; the pre-developed copper-enriched layer advanced the establishment of the steady-state film/alloy interface. Variation of copper-enriched layer structure is revealed by the detection of copper-rich nanoparticles in the copper-enriched layer. The copper-rich nanoparticles have structures consistent with either θ", θ' or θ phases. Machining damage can be detected not only by chromic acid anodising (CAA) but also by tartaric-sulphuric acid anodising (TSAA). Neither CAA nor TSAA can be used for detecting shallow corrosion pits.EThOS - Electronic Theses Online ServiceEPSRC LATEST Portfolio PartnershipAirbus Operations LimitedGBUnited Kingdo

Modeling the Perceptions and Preferences of Pedestrians on Crossing Facilities

Pedestrian’s street-crossing behaviour has a significant effect on traffic performance and safety. The crossing behaviour is determined by human factors and environmental factors. Aiming at examining the pedestrian perceptions toward crossing facilities and preferences for crossing locations, an observational study of pedestrian crossing behaviour at urban street is conducted. The perceptions and preferences of pedestrians are collected using stated preference technique. A specific questionnaire is designed to conduct the stated preference survey. A multinomial logit model is proposed to describe the perceptions and preferences of pedestrians on crossing facilities and locations. The sensitivity analysis is performed to discuss the influence of various factors on crossing behaviour. Then the relationship between crossing locations and crossing distances is analyzed by a new proposed method. With the theoretical analysis, the engineering solutions considering pedestrian behaviour are suggested. The results are helpful to design human-centered crossing facilities in urban traffic

Cryopreservation in Ophthalmology

Amniotic membranes (AMs) and corneas are critical materials in ocular surface reconstruction. AM has specific structures (e.g., basement and two types of cells with stemness characteristics: amniotic epithelial cells and amniotic mesenchymal cells), which contribute to its attractive physical and biological properties that make it fundamental to clinical application. The corneal endothelial cell is a vital part of the cornea, which can influence postoperative vision directly. However, widespread use of fresh AM and cornea has been limited due to their short use span and safety concerns. To overcome these concerns, different preservation methods have been introduced. Cryopreservation is distinguished from many preservation methods for its attractive advantages of prolonged use span, optimally retained tissue structure, and minimized infection risk. This review will focus on recent advances of cryopreserved AM and cornea, including different cryopreservation methods and their indications in ophthalmology

PO-081 Overtraining results in abnormality of renal silt diaphragm in rats with persistent proteinuria

Objective Silt diaphragm is the most important and bioactive membrane structure in the filtration barrier of kidney, and the root cause of proteinuria is the structural and functional abnormalities of Silt diaphragm. So far, there is little literature on the changes of silt diaphragm caused by overtraining. This research establishes a model of rats with exercise-induced proteinuria with long-term intensitive treadmill exercise, and it simulates the progressive-load training in the cycle of athletes. Histological and ultrastructural changes of kidney immediately and 24 h after exercise are observed, and it aims to analyze the change law of silt diaphragm during the occurrence of persistent proteinuria. Methods this study selects 36 Sprague-Dawley rats, which are randomly divided into 3 groups: a control group (group C, 12), a group drawn immediately after exercise(group EI, 12), a group drawn 24 h after exercise(group EA, 12). Group C does not train. The rats in group EI and EA train on the treadmill with an increasing load for 6 weeks(10% grade, 6 d/w): in the first week, the rats run for 10 min at 10 m/min. Starting from the second week, the running speed increases by 5m/min/w, and the training time increases by 30min/w. In the last week the rats run to exhaustion if they could not maintain the target intensity. Record the exhausting time of rats, then group EI and group EA are respectively drawn immediately and 24 hours after exercise. Observe the histological changes of  renal glomerulus by optical microscope, and the ultrastructure of silt diaphragm by TEM. Detect urine total protein by BCA, serum and urine creatinine by Jaffe, serum testosterone and corticosterone by radioimmunoassay, serum urea by two-point dynamic method, and the expression of Nephrin by western-blot. Results The rats in group EI and EA gradually lose weight at the first weekend of training, and their weight drop significantly from the third weekend to the end, it shows a significant difference compared with group C(p<0.01). There is no significant difference between the exercise group. Glomerular morphology, group C: The structure of glomerulus is compact, the boundary between vascular sphere and  the wall of capsule is obvious, and the distribution of erythrocytes in vessels is regular; Group EI: The thickness of glomerulus membrane is uneven, the structure of the podocyte is incomplete, part of the foot process is fused, and SD is discontinuous; Group EA: Part of the glomerular endodermis is abnormal, part of the foot process is fused, detached, and unevenly distributed, and SD is discontinuous. Total protein/ creatinine in urine of rats 30 min and 24 h after exercise is significantly higher than that of group C(p<0.01), and group EA is slightly retuned and lower than group EI(p<0.05). Compared with group C, Serum Testosterone/Corticosterone of rats in group EI and EA is significantly decreased, and there is a significant difference (p<0.01). However, there is a significant decrease in EA group but it is still significantly lower than group EI(p<0.01). Serum corticosterone is significanty decreased in group EI and EA, and there is a significant difference (p<0.01), while group EA is significantly decreased but still significantly lower than that in group EI(p<0.01). Serum urea and espression of Nephrin are significantly decreased in group EI and EA(p<0.01), but there are no significant difference between group EI and EA(p>0.05). Conclusions The rats suffer from overtraining syndrome caused by intensitive training, and with persistent proteinuria, their renal function is disordered and cannot be effectively recovered after 24 h rest. Meanwhile, the renal morphology and ultrastructure of silt diaphragm in rats undergo "pathogenical-like" changes, which do not significantly decrease with the extension of recovery time. It is revealed that the injury of renal structure and ultrastructure of silt diaphragm caused by overtraining are the structural basis of continuous exercise-induced proteinuria

PO-032 The protective effects of curcumin on exercise-induced renal ischemia reperfusion injury in rats

Objective This study was designed to investigate the effects  of curcumin on inflammatory factors and ECM expression in exercise-induced renal ischemia reperfusion injury in rats. Methods Sixty 7-week-old male SD rats were divided randomly into three groups: group A (normal control group, n=12), group B (overtraining group, n=24) and group C (curcumin + overtraining group, n=24). Group B and C  performed 6 weeks of incremental load training on the treadmill.  24 hours after the last training, the rats were anesthetized intraperitoneally, the morphology of renal tissue and the deposition of glomerular ECM were observed using light microscope，the related biochemical indexes were tested. Results (1) the renal structure of rats in group A were normal,  histopathological changes were observed  in group B and  C, Paller score of group B were significantly higher than group A(P <0.01), and that of group C were significantly lower than group B(P <0.05). (2) Blood urea nitrogen (BUN) and serum creatinine (Scr), serum and renal inflammatory factors , TGF-β protein expression level and glomerular ECM deposition of  group B  were significantly higher than group A(P<0.01)  and those of group C were lower than group B(P<0.05). Conclusions  Supplementation of curcumin can effectively  protect rats from exercise-induced renal ischemia reperfusion injury, by inhibiting the up-regulation of inflammatory cytokines and TGF-β expression and maintaining the dynamic balance of ECM

The effect of the interaction of sleep onset latency and age on ischemic stroke severity via inflammatory chemokines

ObjectiveProlonged sleep onset latency (PSOL) and age have been linked to ischemic stroke (IS) severity and the production of chemokines and inflammation, both of which contribute to IS development. This study aimed to explore the relationship between chemokines, inflammation, and the interplay between sleep onset latency (SOL) and age in influencing stroke severity.MethodsA cohort of 281 participants with mild to moderate IS was enrolled. Stroke severity was assessed using the National Institutes of Health Stroke Scale (NIHSS), and SOL was recorded. Serum levels of macrophage inflammatory protein-1alpha (MIP-1α), macrophage inflammatory protein-1beta (MIP-1β), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) were measured.ResultsNIHSS scores of middle-aged participants with PSOL were significantly higher than those with normal sleep onset latency (NSOL) (p = 0.046). This difference was also observed when compared to both the elderly with NSOL (p = 0.022), and PSOL (p < 0.001). Among middle-aged adults with PSOL, MIP-1β exhibited a protective effect on NIHSS scores (β = −0.01, t = −2.11, p = 0.039, R2 = 0.13). MIP-1α demonstrated a protective effect on NIHSS scores in the elderly with NSOL (β = −0.03, t = −2.27, p = 0.027, R2 = 0.12).ConclusionThis study reveals a hitherto undocumented association between PSOL and IS severity, along with the potential protective effects of MIP-1β in mitigating stroke severity, especially among middle-aged patients

PL-011 Astaxanthin Reduces High Intensity Training Induced Myocardial Cell Apoptosis Via Activating Nrf2 in Rats

Objective Long-term intensive training may led to ischemia oxygen reaction and increase the ROS. Astaxanthin, as the super antioxidant, was investigated to against anti-oxidative stress. By supplementing the astaxanthin, we wanted to observe if it can mediated Nrf2 reduces myocardial cell oxidative injury in rats after high intensity training of 6 weeks.  Methods 7-week SD male rats were divided into 3 groups randomly: control group ( C group，n =10)，high intensity training group ( HT group，n = 15)，astaxanthin and high intensity training group (HTA group，n = 15) . The rats in HTA group were given with astaxanthin 20 mg /kg·d and in HT group were given with oil during the training day．The serum cTnI，myocardial apoptosis index,  the expression of myocardial BAX, Bcl2, Nrf2, HO-1, myocardial MDA，SOD and T- AOC activity were measured 24 hours after the last training． Results After 6-week tranning of high intensity, compared with group C, the serum cTNI, myocardial apoptosis index, the expression of BAX and myocardial MDA were significantly higher in group HT(P<0.01).The Bcl2/Bax, the expression of HO-1, SOD and T-AOC activity were significantly declined (P<0.01). After the intervention of 6-week astaxanthin, compared with group HT, the serum cTNI, myocardial MDA, the myocardial apoptosis index, the expression of BAX were significantly lower in HTA group (cTNI(ng/ml): 1.16±0.27 VS 2.47±0.39, P<0.05; myocardial apoptosis index: 164.27±3.98 VS 196.20±9.65, P<0.01; BAX: 58.40±5.95 VS 78.03±3.80, P<0.01 ). Finally, Bcl2/Bax, SOD, T-AOC activity, the expression of Nrf2 and HO-1 were significantly higher  (Bcl2/Bax : 1.92±0.10 VS 1.19±0.18, P<0.01; SOD(U/mg): 52.38±6.15 VS 38.32±3.36, P<0.01; T-AOC(U/mg): 30.22±4.07 VS 23.76±3.20, P<0.01; Nrf2: 93.61±8.53 VS 74.26±6.69, P<0.01; HO-1: 84.99±13.78 VS 64.22±11.39, P<0.05).  Conclusions The supplement of astaxanthin can mediate Nrf2 signaling pathway, and elevate the expression of Nrf2 and HO-1. Then it can increase the activity of SOD and T-AOC and reduce the myocardial oxidative level and myocardial apoptosis in rats caused by 6-week high intensity training. Finally, the structure and function of heart tissue are back to normal