In situ synchrotron tomographic evaluation of the effect of toughening strategies on fatigue micromechanisms in carbon fibre reinforced polymers

Micromechanisms of fatigue failure in double-notch cross-ply carbon/epoxy coupons have been investigated using synchrotron radiation computed tomography (SRCT). The fatigue behaviour of toughened and untoughened matrices has been compared, highlighting similarities and differences of damage modes in terms of fatigue initiation and propagation. Results show that damage does not propagate evenly for the toughened systems: the presence of resin rich regions constrains crack propagation, which is shown to suppress damage growth. In contrast, untoughened material is characterized by more uniform crack progression. The presence of toughening particles in the resin system favours complex local crack geometries, such as crack deflection and the formation of bridging ligaments along the crack wake due to particle debonding events. A distinctive aspect of fatigue loading is identified in the degradation of crack bridging ligaments associated with increasing number of cycle

Fatigue micromechanism characterisation in carbon fibre reinforced polymers using synchrotron radiation computed tomography

In situ synchrotron radiation computed tomography (SRCT) has been used to evaluate fatigue damage micromechanisms in [90/0]s carbon fibre reinforced epoxy double-edge notched specimens. Interactions between cracks and toughening particles have been identified within the epoxy, particularly: particles de-bonding ahead of the main crack tip, creating a preferential damage path, and the bridging of cracks by un-failed ligaments. The critical mechanism of fatigue crack growth appears to be the degradation of bridging ligaments in the crack wake. Damage has been quantified in terms of crack opening and shear displacements, and the results have been compared with corresponding damage occurring due to quasi- static loading of the same materials. The removal of bridging ligaments in fatigue loading results in higher, more uniform crack opening (and shear) displacements and less serrated crack fronts. These observations have potential implications for material development, damage resistant and damage toler- ant structural design approache

High-resolution computed tomography in resin infused woven carbon fibre composites with voids

Tomographic imaging using both microfocus radiation and synchrotron radiation was performed to assess the void defects in resin transfer moulded woven carbon fibre composites. The focus of this study is on characterising the void homology (e.g. local void size and spatial distribution) in relation to weave orientation, infusion direction and potential effects on damage formation in tensile loading. As the orientation angle between the fibre direction of unidirectional layer in the laminate and the direction of the global resin flow increases, from parallel to perpendicular, larger voids and a greater volume fraction of voids were observed, which led to increased damage formation upon loading. Significant accumulation of voids around both the layer interfaces and yarn fibres were also observed. With regard to yarn design, it is recommended to balance the benefits (e.g. fabric handling, structural integrity of preform) and drawbacks (e.g. lower fibre content, more voids) of the supporting yarn. Also, sensible placement of resin inlets and outlets could reduce the amount of deleterious voids, i.e. by promoting resin flow along the fibre direction in the most defect-sensitive off-axis layers

Use of inflammatory markers to guide cancer treatment

Patient-related factors, especially markers of inflammatory response, are prognostic in many common solid cancers. Here we review how such markers, in particular the acute-phase proteins C-reactive protein and albumin and a differential white cell count, can predict treatment outcomes in cancer patients. The review examines the literature pertaining to surgery, chemotherapy, and radiotherapy and discusses how inflammatory markers might be incorporated into the planning and monitoring of cancer treatments

Virus-like particles as a vaccine delivery system: myths and facts.

Vaccines against viral disease have traditionally relied on attenuated virus strains or inactivation of infectious virus. Subunit vaccines based on viral proteins expressed in heterologous systems have been effective for some pathogens, but have often suffered from poor immunogenicity due to incorrect protein folding or modification. In this chapter we focus on a specific class of viral subunit vaccine that mimics the overall structure of virus particles and thus preserves the native antigenic conformation of the immunogenic proteins. These virus-like particles (VLPs) have been produced for a wide range of taxonomically and structurally distinct viruses, and have unique advantages in terms of safety and immunogenicity over previous approaches. With new VLP vaccines for papillomavirus beginning to reach the market place we argue that this technology has now 'come-of-age' and must be considered a viable vaccine strategy

Safety of hospital discharge before return of bowel function after elective colorectal surgery

© 2020 BJS Society Ltd Published by John Wiley & Sons LtdBackground: Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function. Methods: A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien–Dindo classification system. Results: A total of 3288 patients were included in the analysis, of whom 301 (9·2 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4–7) and 7 (6–8) days respectively (P < 0·001). There were no significant differences in rates of readmission between these groups (6·6 versus 8·0 per cent; P = 0·499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0·90, 95 per cent c.i. 0·55 to 1·46; P = 0·659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34·7 versus 39·5 per cent; major 3·3 versus 3·4 per cent; P = 0·110). Conclusion: Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients

Safety of hospital discharge before return of bowel function after elective colorectal surgery

Background: Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function. Methods: A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien\u2013Dindo classification system. Results: A total of 3288 patients were included in the analysis, of whom 301 (9\ub72 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4\u20137) and 7 (6\u20138) days respectively (P &lt; 0\ub7001). There were no significant differences in rates of readmission between these groups (6\ub76 versus 8\ub70 per cent; P = 0\ub7499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0\ub790, 95 per cent c.i. 0\ub755 to 1\ub746; P = 0\ub7659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34\ub77 versus 39\ub75 per cent; major 3\ub73 versus 3\ub74 per cent; P = 0\ub7110). Conclusion: Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients