Compressive strength after blast of sandwich composite materials

Composite sandwich materials have yet to be widely adopted in the construction of naval vessels despite their excellent strength-to-weight ratio and low radar return. One barrier to their wider use is our limited understanding of their performance when subjected to air blast. This paper focuses on this problem and specifically the strength remaining after damage caused during an explosion. Carbon-fibre-reinforced polymer (CFRP) composite skins on a styrene-acrylonitrile (SAN) polymer closed-cell foam core are the primary composite system evaluated. Glass-fibre-reinforced polymer (GFRP) composite skins were also included for comparison in a comparable sandwich configuration. Full-scale blast experiments were conducted, where 1.6×1.3 m sized panels were subjected to blast of a Hopkinson-Cranz scaled distance of 3.02 m kg(-1/3), 100 kg TNT equivalent at a stand-off distance of 14 m. This explosive blast represents a surface blast threat, where the shockwave propagates in air towards the naval vessel. Hopkinson was the first to investigate the characteristics of this explosive air-blast pulse (Hopkinson 1948 Proc. R. Soc. Lond. A 89, 411-413 (doi:10.1098/rspa.1914.0008)). Further analysis is provided on the performance of the CFRP sandwich panel relative to the GFRP sandwich panel when subjected to blast loading through use of high-speed speckle strain mapping. After the blast events, the residual compressive load-bearing capacity is investigated experimentally, using appropriate loading conditions that an in-service vessel may have to sustain. Residual strength testing is well established for post-impact ballistic assessment, but there has been less research performed on the residual strength of sandwich composites after blast.

Development, implementation, and evaluation of an institutional daily awakening and spontaneous breathing trial protocol: a quality improvement project

INTRODUCTION

While one controlled trial found that a daily awakening and spontaneous breathing trial (DA-SBT) decreases time on mechanical ventilation (MV), there is a paucity of real-world data surrounding the development, implementation, and impact of DA-SBT protocols. We describe a multidisciplinary process improvement effort in 2, 10-bed medical intensive care units (MICUs) at a 330-bed academic medical center that focused on the development, implementation, and evaluation of a new DA-SBT protocol.

METHODS

A DA-SBT protocol, developed using results from a nursing survey literature and available institutional resources, was implemented after extensive clinician education and institution of quality reminders to boost use. Postprotocol compliance was evaluated. Use of sedation, DA and SBT practices, and clinical outcomes were retrospectively compared between the before and after DA-SBT protocol groups (ie, consecutive MICU patients requiring a continuously infused sedative [CIS] ≥24 hours).

RESULTS

In the after group (n = 32), the DA and SBT compliances were 44% and 84%, respectively. Compared with the before group (n = 33), after group patients received CIS on fewer days of MV (100% vs 67%, P = .003) and had their CIS down-titrated by ≥25% on more days of CIS (40% vs 71%, P = .006). Neither total CIS dose (P = .49), total MV days (P = .75), days of MV where a SBT occurred (P = .38), nor episodes of self-extubation (15% vs 6%, P = .43) differed between the 2 groups.

CONCLUSION

Despite the implementation of a DA-SBT protocol that was individualized to clinician preferences and institutional resources and accompanied by substantial education and reminders for use, compliance to the DA component of this protocol was low and duration of MV remained unchanged. Additional quality improvement strategies are needed to overcome barriers to DA-SBT protocol use that may not exist in controlled clinical trials.

Pandemic influenza A (H1N1) 2009 in a critical care and theatre setting: beliefs and attitudes towards staff vaccination

West Midlands was particularly affected by the 2009 H1N1 influenza A (pH1N1) pandemic. Vaccination of frontline healthcare professionals (HCPs) aimed to prevent spread to vulnerable patients, minimise service disruption and protect staff. HCPs involved in upper airway management are particularly at risk of aerosol exposure. We assessed the attitudes of these HCPs towards pandemic influenza A (H1N1) 2009 vaccination uptake: primary reasons for acceptance, barriers to vaccination, and knowledge surrounding pH1N1 influenza. We performed a voluntary, anonymous questionnaire survey based in two West Midlands National Health Service Trusts, one month after introduction of the vaccine. In all, 187 useable responses were received (60.5% response rate); 43.8% (N=82) had/intended to receive vaccination. Concern over long term side-effects was the main deterrent (37.4%, N=70). Primary reasons for potentially accepting vaccination were: to protect themselves (36.9%, N=69), to protect family (35.3%, N=66), and to protect patients (10.2%, N=19). Of responders, 76.5% were unsure that the vaccines had undergone suitably rigorous clinical trials to ensure safety; 20.9% correctly identified reported vaccine efficacy. We conclude that pH1N1 vaccination uptake among high risk HCPs remained low, although twice that of peak seasonal influenza vaccination rates. HCPs' knowledge of vaccine efficacy is poor. Barriers to vaccination include concerns over safety profile given the short chronological time-span between the pandemic being declared and vaccine introduction. Side-effects, both acute and chronic, are a significant barrier to vaccination. Further reassurance/education surrounding vaccine safety/efficacy at the time of any future pandemic may improve uptake rates.

[Fertility, maternal mortality and survival of the children in the medical district of Kolda (Senegal)]

Maternal mortality and lethality in childhood constitute a major problem in Senegal. These two rates are often hight in areas off hight birth rate. In the medical district of Kolda (Senegal) no reliable data on reproductive health exists. We report the results of a preliminary investigation of a community based reproductive project. We've used the sisterhood methods reproductive health's indicators. This cross-sectional study was carried out in a sample of 1287 women in age of procreating. An "aggregative" fertility index of 6.59 was found in the "intervention" area as compare to 5,53 in the control area. The maternal death rate was estimated at 1285 per 100.000 alive births [998-1576]. The infant mortality rate was 83 per 1000. These results justify impremantation of a "vigorous" reproductive health policy in this area.

[Buprenorphine as a new alternative for detoxification of heroin addicts. It causes only mild withdrawal problems, abating quickly]

Buprenorphine might be an alternative drug to be used in opiate detoxification. Its main advantage is that it carries a low risk for respiratory depression, it gives less euphoria and limited withdrawal effects. In a pilot detoxification project ten heroin addicts were given buprenorphine; seven completed the course. Before detoxification seven patients showed five or more signs on the Himmelsbach scale [6]. After the second day four patients showed no signs, four patients displayed one sign, two patients two signs. Buprenorphine may be a valuable alternative to clonidine, dextropropoxiphene and methadone in the detoxification of opiate addicts.

[Ecology and postmodernity. An ethical point of view]

This essay deals with critique of the "Modern Reason". Also, it aims to promote the debate about ethical and political issues of our technological/eco-depredating and environmentally unsound model of development. We argue about ecology like a new knowledge point of view, from which to define criteria for the reformulation of the environment/society relationship, in a postmodern context.