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A prominent size effect has previously been reported for the fracture behaviour of brittle porous materials, with smaller specimens behaving quite differently to their larger counterparts. In such materials, the size of the K-dominant zone has been numerically found to be greatly affected by the presence of voids in the near-tip area, thus putting the assumption of a single fracture parameter under question. In order to address this, in this study mode I tests are conducted on porous double cantilever beam specimens, while the stress distribution in the near-tip area is being observed by means of photoelasticity. Results validate the predicted size effect and suggest that the voids can indeed alter the size and shape of the stress pattern in the specimens. A parametric study is then conducted to investigate the influence of void shape variations that can be caused by manufacturing inaccuracies on the stress concentration at the crack tip. It is found that although the stress intensity at the crack tip can be greatly affected by such factors, the size of the K-dominant zone remains unaffected. Unlabelled Image • Experiments on brittle porous materials show size effect of stress intensity • Experimental values validate numerical predictions and trends in variation • Voids affect stress field, indicating the significance of non-singular stresses • Void shape variations affect stress intensity, but K-dominant zone size is constant • Mesostructural material parameters are linked with behaviour of specimens [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • In porous materials, non-singular stresses in the near-tip area become significant. • Porous materials exhibit a size effect which is attributed to non-singular stresses. • Non-singular stresses affect the macro- and mesoscopic stress distribution. • A relation is suggested to predict the fracture behaviour of porous materials. Abstract Linear Elastic Fracture Mechanics usually only considers the singular stresses when describing the conditions under which fracture would occur in a brittle material. However, it is becoming more widely recognised that non-singular stresses can become significant depending on the geometry and configuration of the specimen. This study investigates the impact of non-singular stresses on the stress intensity of low to medium porosity brittle materials. To address this, discrete finite element models of Double Cantilever Beam (DCB) samples were created and the full near-tip stress field in mode I loading was numerically evaluated. A parametric study was conducted, examining the influence of overall specimen size, material porosity and crack tip location relative to the nearest void. Results indicate a prominent size effect on the stress intensity at the crack tip of porous materials, with smaller specimen exhibiting tougher behaviour than their respective larger counterparts. This size effect, which is amplified with increasing porosity, is closely correlated with the variation of non-singular stresses, both parallel and normal to the crack plane. A model to predict the behaviour of porous specimen for different sizes is suggested based on the findings. [ABSTRACT FROM AUTHOR]

Abstract: The 4q deletion syndrome, comprising all microscopically visible deletions (interstitial and terminal) is a well-recognized distinctive malformation entity, with an estimated incidence of 1:10,000. Here we present the clinical and molecular findings in a 3-year-old male with a de novo distal deletion of 4q33 [46,XY,del(4) (q33)]. Clinical findings of the patient include: hypertelorism, broad nasal bridge, short nose with anteverted nares, long philtrum, thin upper lip, micro-retrognathia, low-set and protruding ears, pre-auricular tag unilaterally, low posterior hairline, clinodactyly of the 5th fingers, tapering fingers, hypospadias, and severe psychomotor retardation. Soon after birth he developed severe hypotonia and feeding difficulties. Echocardiography at 15months documented aortic supravalvular membrane resulting in mild aortic stenosis and dysplasia of the pulmonary valve. Genome-wide screening using 1Mb resolution array-CGH and subsequent FISH analyses defined a 18.9–22.9Mb deletion located at the beginning of 4q33 and extending to the telomere. The description of additional cases with similar distal deletions of 4q33 will allow a more precise prognosis and is therefore of great value for genetic counsellors, while detailed molecular characterization in any well clinically characterized patient is expected to track down individual candidate genes for the specific features of the syndrome. [Copyright &y& Elsevier]

Abstract: We report on a 13-year-old girl with normal karyotype and a de novo cryptic terminal deletion of chromosome 2q, detected by subtelomeric FISH analysis. Further investigation with array-CGH analysis using the 1Mb resolution Spectral Chip 2600 (Spectral Genomics) confirmed the deletion and also showed a deletion of four additional clones. No other abnormalities were detected by array-CGH. FISH studies using 8 BAC-probes were performed for fine mapping of the deletion and confirmed the array results. FISH analysis showed that the deletion breakpoint lies between clones RP11-84G18 and RP11-83N2 (physical distance between clones 0.36Mb) and extends to the telomere. The size of the deletion was estimated to be about 6.4–6.7Mb. Clinical findings include: developmental delay, severe behavioural disturbances, growth-pubertal retardation, congenital conductive mild hearing loss, growth hormone deficiency, compensate hypothyroidism, dysmorphic facial features, excessive joint hypermobility, brachymetaphalangy, abnormal dermatoglyphics and a history of neonatal laryngomalacia, hypotonia and umbilical hernia. The phenotype of our patient is in keeping with those of the literature, with the exception of cardiovascular, urogenital, neurological anomalies and eczema, which were not observed. The report of the clinical and molecular presentation of similar cases will allow accurate phenotype–genotype correlation and proper genetic counseling of the family. [Copyright &y& Elsevier]