Structural integrity assessment of orc turbine tie-rods: An analysis based on elastic shakedown and fracture mechanics

Fatigue life assessment of turbine rotating components is usually performed taking into account the presence of potential defects and their propagation, together with an accurate description of the stress/strain fields acting at components critical regions. In this work, such an approach was applied on a radial outflow turbine: the component investigated in this paper is the tie-rod. An axisymmetric FEM model of the whole turbine was implemented to evaluate the stress field acting at the root of tierod thread, the component most critical region. Three different preload procedures were investigated, in order to evaluate the effects of plastic strains on fatigue cycles. It was found that an initial overtightening, performed before machine assembly, induces a larger plastic zone at the root of the thread, which lowers the peak stress and lessens the stress ratio of the fatigue cycle. Stress gradients for the three different preloading conditions were the starting point of a crack propagation model, which calculated crack advancement as a function of service time. The model, which considered crack closure and stress ratio effects, allowed structural integrity assessment and showed that the initial overtightening had also the effect of crack growth rates reduction

In situ diagnostic methods for catheter related bloodstream infection in burns patients: a pilot study

Background One of the most common and potentially fatal complications in critically ill burns patients is catheter related bloodstream infection (CR-BSI). Lack of in situ diagnostic techniques requires device removal if CR-BSI is suspected with 75-85% of catheters withdrawn unnecessarily. Aims To assess the sensitivity, specificity and accuracy of two in situ diagnostic methods for CR-BSI in an adult ICU burns population: Differential Time to Positivity (DTP) and Semi-Quantitative Superficial Cultures (SQSC). Methods Both arterial (AC) and central venous (CVC) catheters were studied. On clinicians' suspicion of CR-BSI, the CVC and AC were removed. Superficial semi-quantitative cultures were taken by removing the dressings and swabbing within a 3 cm radius of the CVC and AC insertion sites, as well as inside each hub of the CVC and AC. Peripheral blood was taken for qualitative culture and the catheter tip sent for semi-quantitative culture. DTP was considered positive if culture of lumen blood became positive at least 120 min before peripheral blood with an identical pathogen. Superficial and tip cultures were identified as positive if ≥15 CFUs were grown. CR-BSI was confirmed when both catheter tip culture and peripheral blood culture were positive with the same micro-organism. Results Sixteen patients (88% male) with an APACHE II score of 22.0 (7.3) were enrolled. The mean age was 45.7 (16.9) years with mean total burn surface area 32.9 (19.4)%. Fifty percent had airway burns. ICU stay was 19.9 (11.1) days. All 16 survived ICU discharge with a hospital survival of 93%. There were 20 episodes of CR-BSI in these 16 patients. For these 20 episodes the exposure time (line days) was 113.15. The CR-BSI rate was 15.6 per 1000 catheter days (95% CI 1.9-56.4). For diagnosis of CR-BSI in either AC and CVC, SQSC had a sensitivity of 50% [95% CI 3-97], specificity 83.3% [95% CI 67-93], PPV 14.3 [95% CI 1-58], NPV 96.8 [95% CI 81-100], accuracy of 81.6% [95%CI 65-92] and diagnostic odds ratio 5.0 [95% CI 0.3-91.5]. To diagnose tip colonisation (>15CFU), sensitivity of SQSC was 75% [95% CI 22-99], specificity 88.2% [95%CI 72-96], PPV 42.7 [95% CI 12-80], NPV96.8% [95% CI 81-100], accuracy 86.8% [95% CI 71-95] and diagnostic odds ratio 22.5 [95% CI 1.9-271.9]. For combined DTP blood cultures, sensitivity for CR-BSI was 50% [95% CI 3-97], with specificity 97% [95% CI 82-100], PPV 50% [5% CI 3-97%], NPV 97% [95% CI 82-100], accuracy 94.3% 95% CI 79-99] and diagnostic odds ratio 32 [95% CI 1.1-970.8]. Conclusion Both DTP and SQSC displayed high specificity, NPV and accuracy in a population of adult burns patients. These features may make these tests useful for ruling out CR-BSI in this patient group. This study was limited by a low number of events and further research is required

Un approccio integrato per la conoscenza e conservazione in funzione della mostra alla Galleria d’Arte Moderna: 100 anni. Scultura a Milano 1815-1915

In occasione della mostra “100 Anni. Scultura a Milano 1815-1915” organizzata dalla GAM - Galleria d’Arte Moderna di Milano, è stata condotta un’attività di ricerca che ha visto la stretta collaborazione tra i restauratori, gli esperti di diagnostica e monitoraggio e i conservatori. Le diverse competenze hanno permesso un approccio integrato finalizzato all’incremento della conoscenza ed alla conservazione di una selezione di opere provenienti dai depositi della Galleria, in vista della loro nuova esposizione museale. La GAM conserva una grande quantità di sculture del XIX secolo, realizzate con materiali differenti che includono marmo, bronzo e gesso. La loro storia conservativa non è omogenea e se per molte di esse lo stato attuale risente solo dei depositi di sporco ambientale, altre hanno subito nel tempo momenti di scarsa considerazione. Tra queste ultime, le sculture in gesso, che solo negli ultimi decenni hanno finalmente ottenuto il dovuto riconoscimento. Le statue in marmo presentano uno stato di conservazione differenziato, in una scala di valori che descrive tutti i livelli di sporco, dalle opere di recente esposizione in museo, quindi relativamente pulite, fino alle sculture completamente annerite, con depositi carboniosi, tracce di percolazioni e un’erosione delle superfici che rivelano una precedente permanenza all’aperto. I principali problemi riscontrati sui gessi comprendono sia degradi superficiali, con stratificazioni di depositi più o meno penetrati nel gesso, sia situazioni di precarietà strutturale, con presenza di frammentarietà e lacune anche di parti importanti come i volti o gli arti in posizioni aggettanti. Le sculture appaiono complessivamente annerite, con segni bianchi dovuti ad abrasioni o a recenti rotture. La complessità dei materiali di sostegno presenti all'interno (legni, ferri, ossa), interagendo con il gesso in condizioni di umidità ambientale, provoca ulteriori processi di degrado. Inoltre, la presenza di una pellicola giallognola che ricopre in modo disomogeneo la superficie di alcuni gessi (come nel caso della Maddalena di Pompeo Marchesi) è stata oggetto di un approfondimento di studio specifico per caratterizzarne la natura e chiarirne l’origine. L’attività diagnostica è stata finalizzata, in primo luogo, alla caratterizzazione dei materiali costitutivi e delle stratigrafie presenti, anche in relazione alle diverse ed a volte complesse vicende espositive. In una fase successiva, le analisi condotte sono state indirizzate a fornire risposta a specifici interrogativi conservativi e di restauro, emersi preliminarmente o nel corso dell’intervento sulle opere. Il protocollo diagnostico impiegato per le operazioni in situ si è basato inizialmente su analisi di tipo non-distruttivo o micro invasivo, utilizzando strumentazione portatile. Le superfici sono state documentate per mezzo di microscopia digitale e caratterizzate sotto il profilo colorimetrico con misure di spettrofotometria in luce visibile. La raccolta di micro-campioni ha consentito di approfondire gli aspetti stratigrafici e composizionali e di fornire indicazioni operative per le successive attività di restauro, con una diagnostica di laboratorio che ha incluso: analisi in spettroscopia infrarossa e Raman, diffrazione di raggi x, microscopia elettronica a scansione SEM-EDX di micro-frammenti e sezioni trasversali lucide. Il presente lavoro si concentra, in particolare, sul caso della Maddalena di Pompeo Marchesi, che ha richiesto la più completa integrazione delle diverse competenze coinvolte

A pilot study assessing the implementation of 96-well plate-based aggregometry (Optimul) in Australia.

Identification of disordered platelet function is important to guide peri-operative bleeding management as well as long term treatment and prognostic strategies in individuals with platelet bleeding disorders. Light transmission aggregometry (LTA), the current gold standard diagnostic test of platelet function is a time consuming technique almost exclusively performed in specialised laboratories and almost universally unavailable in regional centres in Australia, where there is an unmet need for access to specialised platelet function diagnostic services. 96-well plate-based aggregometry (Optimul, UK), has been utilised in research laboratories as a novel platform to investigate platelet function. We evaluated the Optimul assay at two centres in Australia, one regional and one tertiary metropolitan, to assess its feasibility as a screening test applicable to remote regional centres. Concentration-response curves were established from 45 healthy volunteers at the participating regional hospital and from 31 healthy volunteers at the tertiary institution. Optimul successfully detected anti-platelet effects in individuals taking aspirin (n=4), NSAID (n=2), clopidogrel (n=2) and dual therapy with aspirin and clopidogrel (n=1). When tested in parallel to LTA in individuals referred for the evaluation of abnormal bleeding symptoms there was overall a very good level of agreement between Optimul and LTA [Cohen's kappa (k2)=0.84], supporting its role as a useful screening tool in the assessment of platelet function. Optimul assay performance was quick and the methodology simple, requiring no specialised training or resources to be implemented at either the regional or metropolitan laboratory. Widespread implementation, particularly in regional laboratories within Australia where specialised platelet function testing is unavailable, has the potential to drastically improve the inequity of access to such services

Diagnosis and treatment of MYH9-RD in an Australasian cohort with thrombocytopenia

Published online 1 November 2017MYH9-related disorders (MYH9-RDs) caused by mutation of the MYH9 gene which encodes non-muscle myosin heavy-chain-IIA (NMMHC-IIA), an important motor protein in hemopoietic cells, are the most commonly encountered cause of inherited macrothrombocytopenia. Despite distinguishing features including an autosomal dominant mode of inheritance, giant platelets on the peripheral blood film accompanied by leucocytes with cytoplasmic inclusion bodies (döhle-like bodies), these disorders remain generally under-recognized and often misdiagnosed as immune thrombocytopenia (ITP). This may result in inappropriate treatment with corticosteroids, immunosupressants and in some cases, splenectomy. We explored the efficacy of next generation sequencing (NGS) with a candidate gene panel to establish the aetiology of thrombocytopenia for individuals who had been referred to our center from hematologists in the Australasian region in whom the cause of thrombocytopenia was suspected to be secondary to an inherited condition but which remained uncharacterized despite phenotypic investigations. Pathogenic MYH9 variants were detected in 15 (15/121, 12.4%) individuals and the pathogenecity of a novel variant of uncertain significance was confirmed in a further two related individuals following immunofluorescence (IF) staining performed in our laboratory. Concerningly, only one (1/17) individual diagnosed with MYH9-RD had been referred with this as a presumptive diagnosis, in all other cases (16/17, 94.1%), a diagnosis was not suspected by referring clinicians, indicating a lack of awareness or a failing of our diagnostic approach to these conditions. We examined the mean platelet diameter (MPD) measurements as a means to better identify and quantify platelet size. MPDs in cases with MYH9-RDs were significantly larger than controls (p < 0.001) and in 91% were greater than a previously suggested threshold for platelets in cases of ITP. In addition, we undertook IF staining in a proportion of cases and confirm that this test and/or NGS are satisfactory diagnostic tests. We propose that fewer cases of MYH9-RDs would be missed if diagnostic algorithms prioritized IF and/or NGS in cases of thrombocytopenia associated with giant platelets, even if döhle-like bodies are not appreciated on the peripheral blood film. Finally, our report describes the long-term use of a thrombopoietin agonist in a case of MYH9-RD that had previously been diagnosed as ITP, and demonstrates that treatment with these agents may be possible, and is well tolerated, in this group of patients.David J. Rabbolini, Yenna Chun, Maya Latimer, Shinji Kunishima, Kathleen Fixter, Bhavia Valecha, Peter Tan, Lee Ping Chew, Benjamin T. Kile, Rachel Burt, Kottayam Radhakrishnan, Robert Bird, Paul Ockelford, Sara Gabrielli, Qiang Chen, William S. Stevenson, Christopher M. Ward, Marie-Christine Morel-Kop