Exploitation of inherited weakness in fire-damaged building sandstone: the ‘fatiguing’ of ‘shocked’ stone

The problem of the long-term impact of historical fire on masonry is not clearly understood. Much research focuses on the damage that is caused by fire in isolation, and omits to investigate the subsequent exploitation of weaknesses inherited from fire events. Fire can, for example, cause significant physical, chemical and mineralogical change to sandstone, which may then be exploited by background environmental factors such as salt and freeze–thaw weathering. To explore this experimentally, blocks of Peakmoor Sandstone were subjected to a real fire (as well as lime rendering/removal and frost cycle pre-treatments), and their subsequent response to salt weathering cycles was monitored by weight loss and visual assessment of the pattern of surface damage. Results illustrate that the post-fire deterioration of sandstone is strongly conditioned by fracture networks and soot cover inherited from the fire. The exploitation of fractures can lead to spalling during salt weathering cycles — this takes place as granular dissagregation steadily widens cracks and salts concentrate and crystallise in areas of inherited weakness. Soot cover can have a profound effect on subsequent performance. It reduces surface permeability and can be hydrophobic in character, limiting salt ingress and suppressing decay in the short term. However, as salt crystals concentrate under the soot crust, detachment of this layer can occur, exposing fire-damaged stone beneath. Understanding the subsequent exploitation of stone exposed to fire damage by background environmental factors (for example, salt weathering/ temperature cycling) is key to the post-fire management of stone decay.

Children with cerebral palsy: severity and trends over time

Increasingly, more very-low-birthweight infants in the developed world are now expected to survive the neonatal period than was previously the case. There are concerns that there may be a related increase in the number of infants developing severe sensorimotor impairments. Pooled data from five registers contributing to the UK Network of Cerebral Palsy Registers, Surveys and Databases were used to identify patterns of motor impairment in relation to additional impairments and to birthweight, and to assess whether prevalence of cerebral palsy (CP) by birthweight and by severity of motor impairment had changed over time. Low-birthweight infants are at greater risk of developing CP than larger-birthweight babies. The CP rate amongst children with birthweights <2500 g was significantly higher at 16 per 1000 livebirths [95% confidence interval (CI) 14.9, 16.2] than 1.2 per 1000 livebirths [95% CI 11, 1.2] for normal-birthweight children. Despite being at greater risk of developing CP, smaller-birthweight babies are proportionately less likely to develop the most severe forms of motor impairment. Of those born weighing ≥2500 g, 23% compared with 15% weighing <1000 g (P < 0.001) were in the most severely motor impaired group. Severe motor impairment is associated with higher levels of additional impairments. CP rates for each motor impairment group in the 1990s were similar to those in the late 1970s. Rates of CP among infants born below normal birthweight are high but have decreased over time. The CP rate for infants weighing 1000–1499 g at birth decreased from around 180 per 1000 livebirths in 1979 to around 50 per 1000 livebirths from the early 1990s onwards.

Differential expression of steroid 5 alpha-reductase isozymes and association with disease severity and angiogenic genes predict their biological role in prostate cancer

The biological role of steroid 5 alpha-reductase isozymes (encoded by the SRD5A1 and SRD5A2 genes) and angiogenic factors that play important roles in the pathogenesis and vascularization of prostate cancer (PC) is poorly understood. The sub-cellular expression of these isozymes and vascular endothelial growth factor (VEGF) in PC tissue microarrays (n=62) was examined using immunohistochemistry. The effect of SRD5A inhibition on the angiogenesis pathway genes in PC was also examined in prostate cell lines, LNCaP, PC3, and RWPE-1, by treating them with the SRD5A inhibitors finasteride and dutasteride, followed by western blot, quantitative PCR, and ELISA chip array techniques. In PC tissues, nuclear SRD5A1 expression was strongly associated with higher cancer Gleason scores (P=0.02), higher cancer stage (P=0.01), and higher serum prostate specific antigen (PSA) levels (P=0.01), whereas nuclear SRD5A2 expression was correlated with VEGF expression (P=0.01). Prostate tumor cell viability was significantly reduced in dutasteride-treated PC3 and RWPE-1 cells compared with finasteride-treated groups. Expression of the angiogenesis pathway genes transforming growth factor beta 1 (TGFB1), endothelin (EDN1), TGF alpha (TGFA), and VEGFR1 was upregulated in LNCaP cells, and at least 7 out of 21 genes were upregulated in PC3 cells treated with finasteride (25 mu M). Our findings suggest that SRD5A1 expression predominates in advanced PC, and that inhibition of SRD5A1 and SRD5A2 together was more effective in reducing cell numbers than inhibition of SRD5A2 alone. However, these inhibitors did not show any significant difference in prostate cell angiogenic response. Interestingly, some angiogenic genes remained activated after treatment, possibly due to the duration of treatment and tumor resistance to inhibitors. Endocrine-Related Cancer (2010) 17 757-770

Effect of column base strength on steel portal frames in fire

This paper presents the findings of a project part sponsored by an ICE Research and Development grant on portal frames in fire. The research reported here has also lead to a sucessful research grant from the IStructE. The paper describes a non-linear elasto plastic dynamic finite element model that captures the collapse of a portal frame in fire. It demonstrates that current guidance on the column base stiffness and strength, to prevent collapse, may in some cases be unconservative.