Ouabain-insensitive, Na-ATPase activity in pure suspensions of rat kidney proximal tubules

AbstractThe present work was undertaken to evaluate the distribution of the Na-ATPase activity in the different components of the rat kidney cortex. Suspensions of glomeruli, proximal and distal tubules were prepared following a collagenase digestion of outermost kidney cortex slices and a separation on a Percoll gradient. It was found that the Na-ATPase activity is higher in the fraction enriched in proximal tubules. The fraction enriched in glomeruli and in distal tubules show also a Na-ATPase activity, but it is lower

Effect of corrosion degradation on failure mechanisms of aluminium/steel clinched joints

The effect of corrosion phenomena in critical environmental conditions on the mechanical performance of steel/aluminium hybrid joints, obtained by clinching technique, was studied by ageing in salt spray environment. The investigation was carried out on asymmetrical joints with total thickness of 2.5 mm. The joint strength at varying ageing time was determined by means of single lap shear tests.The experimental results have shown that corrosion degradation phenomena significantly affect the performance and failure mechanisms of the joints, causing premature failure of the joint at very low stress level.Moreover, it was observed that the joint geometry characterized by thicker aluminium foil, had good durability properties showing acceptable mechanical properties even at long ageing times. The fracture modes have been analysed in all the above-mentioned conditions and a failure map, at increasing ageing time, for the two joint geometries has been proposed. Keywords: Clinched joints, Durability, Corrosion, Single lap shear test, Failure ma

Effect of repeated salt fog-dry cycles on the performances reversibility of flax fiber reinforced composites

This paper aims to evaluate the effectiveness of flax fiber reinforced epoxy composites (FFRCs) under realistic environmental conditions, contributing to the development of sustainable composite materials for semi-structural outdoor applications. For this purpose, the reversibility of FFRC performance under consecutive and repeated humid-dry aging cycles was investigated for the first time. In particular, FFRCs were exposed to three cycles (total aging time of 12 weeks), with each cycle (duration 4 weeks) comprising 10 days of wetting (salt-fog spray; 35 °C, 95 % RH, 5 wt% NaCl solution) and 18 days of drying (22 °C, 50 % RH). Three-point bending tests were carried out up to 18 days of drying within each cycle to monitor changes in the mechanical performances of composites. Water absorption capacity, density and void content were also assessed by tracking weight changes throughout the aging campaign. The experimental results highlighted that the humid phase of each cycle causes degradation of FFRC materials, even though they are able to fully recover their flexural strength during each dry phase, indicating reversible aging. On the other hand, a stiffness permanent reduction was observed due to irreversible degradation phenomena

Assessment of ageing effect on the mechanical behaviour of steel/aluminium self-piercing riveted joint

Self-piercing riveting (SPR) is a new performing technology able to joint several kinds of metal and non-metal supports together. The combined effect of joint configuration and environmental conditions could have detrimental effect on the ageing effect on mechanical behaviour of dissimilar metal SPR joints. The joining of dissimilar materials, such as steel and aluminium, realized by self-piercing riveting (SPR) technique was studied to evaluate the ageing effects on its mechanical behaviour in critical environmental conditions. The investigation was carried out on symmetrical or unsymmetrical joints at varying total thicknesses (i.e. 2.0, 2.5 and 3.0 mm). The joint resistance was determined by single-lap shear tests. A design of experiment (DoE) has been performed by using Minitab® followed by the statistical analysis (ANOVA) of the experimental data. Long-term ageing tests in salt spray environment were performed to evaluate the durability of the mechanical joint. The experimental results evidenced that the corrosion degradation phenomena influenced significantly both the performance and failure mechanisms of the joints; also, the joint configuration is a significant factor for the corrosion effect. In the salt spray, the aluminium sheet undergoes a noticeable degradation due to galvanic Al/Fe corrosion. The set characterized by thinner aluminium sheet evidenced a gradual reduction of the mechanical strength with increasing ageing time due to the prevalence of thinning induced by aluminium corrosion. Instead, for S10-A15 samples (characterized by a thicker thickness of aluminium sheet) during the first 7 weeks, stable mechanical performances were observed. The experimental results evidenced that the corrosion degradation phenomena influence significantly both performances and failure mechanisms of SPR joints. Furthermore, the durability of the SPR joint is strongly affected by the joint configuration, and the best results were observed in the unsymmetrical joint with thicker aluminium sheet

MECCANISMI DI ACCRESCIMENTO E IDENTIFICAZIONE DI DIFETTI MULTIPLI INDOTTI DA IDROGENO (HYDROGEN STEP WISE CRACKING)

Negli acciai, lo sviluppo e la propagazione di cricche interne, dovute alla diffusione di idrogeno, può aver luogo secondo meccanismi diversi. Negi ambienti contenenti H2S in fase acquosa, conosciuti come H2S umido, è frequente lo sviluppo di difetti multipli interconnessi noti come step wise cracks. E' stato osservato che la distribuzione dei bordi grano della matrice metallica ha una notevole influenza sul modo di propagazione di tali difetti. La caratteristica forma ad S delle cricche sembra essere correlata allo scorrimento e alla rottura dei grani cristallini che si trovano nella regione sottoposta a sforzo di taglio tra le cricche che si interconnettono, così come alla propagazione delle cricche stesse attraverso bordi grano ad alto angolo. L'innesco e la propagazione dell'HIC sono influenzati da molteplici fattori di tipo sia ambientale che metallurgico, tali da poter fare propagare i difetti con velocità estremamente elevate (in alcuni casi sono stati registrati valori di velocità di propagazione longitudinale superiori a 15 mm/mese). Nella presente memoria viene evidenziato come l'utilizzo di appropriate tecniche ultrasonore basate sull'analisi del tempo di volo (ToFD) e l'utilizzo di sonde a 45° permette di individuare con buona approssimazione tale tipo di difetti e di poterne seguire l'evoluzione nel tempo

Prevalence of Blood Types and Alloantibodies of the AB Blood Group System in Non-Pedigree Cats from Northern (Lombardy) and Southern (Sicily) Italy

The aims of this study were to determine the prevalence of A, B and AB blood types and alloantibodies in non-pedigree cats from two regions, one in Northern and one in Southern Italy (Lombardy and Sicily, respectively). A total of 448 samples (52.0% from Northern and 48.0% from Southern Italy) were blood typed. The prevalence of A, B and AB blood types in northern and southern cats were 91.0%, 5.2%, 3.8%, and 77.2%, 12.1% and 10.7%, respectively. The prevalence of type-A blood in southern cats was significantly lower (p = 0.0001) than in northern cats, while type-B and AB blood were significantly higher (p = 0.0085 and p = 0.0051, respectively) in Southern compared to Northern Italian cats. Alloantibodies against type-A blood were found in 94.1% of type-B cats, 11.2% of type-A cats had alloantibodies against type-B blood, while no type-AB cats had alloantibodies with no significant difference between the two Italian populations. Type-AB prevalence in non-pedigree cats in Southern Italy was the highest reported in Europe. Italian type-A cats had the lowest worldwide prevalence of alloantibodies against type-B blood. These results highlight the usefulness of regional studies to report different prevalences in feline blood types and reinforce the importance of blood typing cats before transfusions and mating

Critically appraised topic for the most effective and safe treatment for canine generalised demodicosis

Background Canine generalised demodicosis is an inflammatory parasitic skin disease caused by an excessive proliferation of Demodex spp. Generalized demodicosis is a severe skin disease, that can be life threatening if not treated properly. Many of the current treatment options are not licensed for the treatment of generalised demodicosis, it have a low safety margin and may be poorly efficacious and time-consuming for the owner; there is a need for a safe, efficacious treatment for canine demodicosis. Our objective was to systematically review the literature to determine the most effective and safe topical or systemic therapy for canine generalised demodicosis. Single case reports and case series with fewer than five patients were not reviewed as they were considered to be poor quality evidence. A detailed literature search identified 21 relevant clinical trials and these were critically assessed. Results The analysis of the best available evidence on March 5, 2018, suggests that six are the most effective and safe treatments for generalised canine demodicosis including (in alphabetical order): doramectin (oral or parenteral); fluralaner (oral); imidacloprid/moxidectin (topical); ivermectin (oral, not as first choice treatment); milbemycin oxime (oral); and sarolaner (oral). There was insufficient evidence to allow comment on the appropriateness of other treatment protocols for canine generalised demodicosis in this CAT. Conclusions In our critical appraisal of the best scientific literature, there is evidence for recommending the use of 6 therapeutic options against demodectic mange. Further, in vivo, controlled, randomized and blinded clinical trials are required, to evaluate new therapies

Hydroxyapatite Whiskers Based Resin Composite versus Commercial Dental Composites: Mechanical and Biocompatibility Characterization

A systematic evaluation of mechanical and biocompatibility properties of different volume fractions of hydroxyapatite whiskers in comparison with three commercial dental composites filled with micro- and nanosilica particles was carried out. Six groups with different hydroxyapatite whiskers mass fractions were taken into account in order to be compared with the performances of silica particles based composites group. Flexural properties were evaluated via a universal testing machine (2.5 kN Zwick Line) with a 2 kN load-cell (sensitivity 0.001 N). The test was replicated 10 times for the seven experimental groups to better identify statically the significance of the mechanical performances data. MTT quantitative colorimetric assay was performed in order to evaluate the mitochondrial activity of living cells exposed to different resin composites. Data obtained show better interfacial interaction with filler/matrix until 20 wt% of hydroxyapatite whiskers partially replaced silica particles filler. After this threshold, the mechanical performances decrease dramatically due to both the hydroxyapatite agglomerates formation and the low degree of resin conversion. In addition, biocompatibility test showed less cytotoxic effect with the addition of 20 wt% of hydroxyapatite in comparison with higher rates