Progress in strength, toughness and lifetime methods for ceramics

Fortschritte auf dem Gebiet der Festigkeit, Risszähigkeit und Lebensdauer von Keramik Zur Charakterisierung des Versagensverhaltens keramischer Werkstoffe sind Festigkeits- und Risszähigkeitsmessungen erforderlich. Weist eine Keramik noch den Effekt des unterkritischen Risswachstums auf, sind auch Lebensdauermessungen unter statischer Belastung von großer Wichtigkeit. Neuere Beiträge der Autoren zur Untersuchungs-Methodik sind in diesem Bericht zusammengefasst. Teil A befasst sich mit der Berechnung der maximalen Spannungen in runden Scheiben unter Kugelbelastung. Hierbei werden der “ball-on-ring test”, der “ball-on-3-balls test” und der kürzlich von den Verfassern entwickelte „3-balls-on-3-balls test“ betrachtet. Als praktische Anwendung der ermittelten Spannungen im “ball-on-3-balls test” wird das bei grobkörnigem Aluminiumoxid gefundene stabile Bruchverhalten als Effekt einer stark ansteigenden Risswiderstandskurve diskutiert. In Teil B wird auf eine von den Verfassern entwickelte Methode eingegangen, die es gestattet, sehr kurze Kerben mit extrem kleinen Kerbradien zu erzeugen. Bei einer ZrO2-Keramik konnten Kerbradien von unter 0.1 μm bei einer Kerbtiefe von nur 40μm erzeugt werden. Derartig kurze und scharfe Kerben sollten geeignet sein, das Verhalten natürlicher Risse in Keramiken anzunähern. Schließlich wird in Teil C über eine Prozedur berichtet, die sich dafür eignet, eine vorhandene Anzahl an Lebensdauer-Versuchsproben optimal auszunutzen. Hierbei kann aus der erneuten Verwendung von auf niederem Lastniveau angefallenen „Durchläufern“ zusätzliche Information über das Risswachstumsgesetz gewonnen werden. Die Methode wird an Lebensdauermessungen von SIALON in destilliertem Wasser von 20°C demonstriert

A survey of clinical practice patterns in diagnosis and management of Cushing's disease in Iran

Background: Cushing's disease is the most prevalent cause of endogenous adrenocorticotrophic hormone hypersecretion. The aim of this study was to document the current clinical practice pattern in the management of Cushing's disease by Iranian Endocrinologists to determine their opinions and compare them with the current clinical practice guidelines. Methods: An eight-item questionnaire dealing with diagnosis, treatment and follow up of patients with Cushing's disease was developed, piloted, and sent to the members of Iranian Endocrinology Society. Results: Among 90 endocrinologists invited to participate in the survey, 76 replied. Most respondents selected overnight dexamethasone suppression test (ONDST) and assessment of 24-hour urinary free cortisol (UFC) as the best screening tests followed by midnight serum cortisol and midnight salivary cortisol. Classic high dose dexamethasone suppression test and measurement of serum ACTH were selected for localization of the primary lesion by 64.5. The primary choice of treatment was trans-sphenoidal pituitary surgery (86.8). For the recurrence of Cushing's disease, the preferred treatment modality was medical therapy followed by bilateral adrenalectomy, and pituitary re-surgery. In case of treatment failure after the first pituitary surgery and ketoconazole treatment, 51 chose bilateral adrenalectomy, while36.8 selected pasireotide only. Conclusion: ONDST and UFC are two most common tests used to screen an index case with signs and symptoms of hypercortisolism. The primary choice of treatment in Cushing's disease is pituitary surgery. However, medical treatment by ketokonazol is preferred for the recurrences. Pasireotide is the second alternative after bilateral adrenalectomy in case of treatment failure after pituitary surgery and ketoconazole

A survey of clinical practice patterns in diagnosis and management of Cushing's disease in Iran

Background: Cushing's disease is the most prevalent cause of endogenous adrenocorticotrophic hormone hypersecretion. The aim of this study was to document the current clinical practice pattern in the management of Cushing's disease by Iranian Endocrinologists to determine their opinions and compare them with the current clinical practice guidelines. Methods: An eight-item questionnaire dealing with diagnosis, treatment and follow up of patients with Cushing's disease was developed, piloted, and sent to the members of Iranian Endocrinology Society. Results: Among 90 endocrinologists invited to participate in the survey, 76 replied. Most respondents selected overnight dexamethasone suppression test (ONDST) and assessment of 24-hour urinary free cortisol (UFC) as the best screening tests followed by midnight serum cortisol and midnight salivary cortisol. Classic high dose dexamethasone suppression test and measurement of serum ACTH were selected for localization of the primary lesion by 64.5. The primary choice of treatment was trans-sphenoidal pituitary surgery (86.8). For the recurrence of Cushing's disease, the preferred treatment modality was medical therapy followed by bilateral adrenalectomy, and pituitary re-surgery. In case of treatment failure after the first pituitary surgery and ketoconazole treatment, 51 chose bilateral adrenalectomy, while36.8 selected pasireotide only. Conclusion: ONDST and UFC are two most common tests used to screen an index case with signs and symptoms of hypercortisolism. The primary choice of treatment in Cushing's disease is pituitary surgery. However, medical treatment by ketokonazol is preferred for the recurrences. Pasireotide is the second alternative after bilateral adrenalectomy in case of treatment failure after pituitary surgery and ketoconazole

Electrophoretic deposition of biomaterials

Electrophoretic deposition (EPD) is attracting increasing attention as an effective technique for the processing of biomaterials, specifically bioactive coatings and biomedical nanostructures. The well-known advantages of EPD for the production of a wide range of microstructures and nanostructures as well as unique and complex material combinations are being exploited, starting from well-dispersed suspensions of biomaterials in particulate form (microsized and nanoscale particles, nanotubes, nanoplatelets). EPD of biological entities such as enzymes, bacteria and cells is also being investigated. The review presents a comprehensive summary and discussion of relevant recent work on EPD describing the specific application of the technique in the processing of several biomaterials, focusing on (i) conventional bioactive (inorganic) coatings, e.g. hydroxyapatite or bioactive glass coatings on orthopaedic implants, and (ii) biomedical nanostructures, including biopolymer–ceramic nanocomposites, carbon nanotube coatings, tissue engineering scaffolds, deposition of proteins and other biological entities for sensors and advanced functional coatings. It is the intention to inform the reader on how EPD has become an important tool in advanced biomaterials processing, as a convenient alternative to conventional methods, and to present the potential of the technique to manipulate and control the deposition of a range of nanomaterials of interest in the biomedical and biotechnology fields

Using graphene networks to build bioinspired self-monitoring ceramics

We acknowledge the EPSRC Grant Graphene 3D Networks (EP/K01658X/1), EPSRC founded Center for Advanced Structural Ceramics (CASC) at Imperial College London. O.T.P. thanks Nanoforce Technology Ltd. for their facilities and V.G.R. thank the European Commission (FP7—Marie Curie Intra-European Fellowship GRAPES). C.F. thanks the European Commission funding under the 7th Framework Programme (Marie Curie Initial Training Networks; grant number: 289958, Bioceramics for Bone Repair). N.N. acknowledges the funding from Imperial College Junior Research Fellowship. X-ray photoelectron spectra were obtained at the National EPSRC XPS Users’ Service (NEXUS) at Newcastle University, an EPSRC Mid-Range Facility. We acknowledge Dr. I.J.Villar-Garcia support on XPS data processing and analysis