Green's Function of a Dielectric Slab Grounded by Carbon Fiber Composite Materials

The exact solution is obtained for Green's function of an infinitesimal horizontal electric dipole on a dielectric slab backed by a ground plane of carbon fiber composite (CFC) material. We consider both reinforced continuous carbon fiber (RCCF) CFC and carbon nanotube (CNT) CFC. RCCF is modeled by an electrically anisotropic surface impedance tensor whereas CNT is modeled as isotropic. The spectral domain method is used and the asymptotic part of the integrand is treated by adding and subtracting that for a perfect electric conductor ground, leaving a rapidly-converging term for numerical integration. Numerical results based on this method compare well with results based on a time-domain finite integration technique. The effect of conductivity and anisotropy of the composite ground plane on electric field is investigated

Compact Multiband Planar Antenna for 2.4/3.5/5.2/5.8 GHz Wireless Applications

A low-profile planar monopole antenna is proposed to operate within WLAN and WiMax frequency bands. The antenna is composed three radiating elements together with an additional strip to control the antenna performance. An electromagnetic (EM) model of the proposed antenna is developed in CST Microwave Studio for numerical analysis and optimization. The principle of operation and parametric study on the antenna performance are provided. Two dual-band and triple-band antennas are fabricated and experimental results are presented

Performance of microstrip patch antenna on a reinforced carbon fiber composite ground plane

Using mass-produced multiwall carbon nanotubes (MWCNTs) from different providers, we have fabricated nanocomposites with high and nearly constant shielding effectiveness (SE) over a wide frequency range up to 26.5 GHz. The MWCNT weight fraction and sample thickness were lower than 10% and 2 mm, respectively. The fabrication process and percolation curves are described. A high dc conductivity of 239.1 S/m was achieved at an MWCNT loading of only 8% by weight. The effect of aspect ratio on shielding performance is addressed. By comparing the measured SE of the composite with predictions from a model of the measurement setup using Microwave Studio, the effective conductivity of the nanocomposite was determined. Since the thickness is very important for shielding analysis, the SE/unit thickness diagram was calculated by using the effective parameters of samples. The results were verified experimentally by measuring the SE of samples with different thicknesses

Carbon Nanotube Composites for Wideband Millimeter-Wave Antenna Applications

In this paper, we explore using carbon nanotube (CNT) composite material for wideband millimeter-wave antenna applications. An accurate electromagnetic model of the composite antenna is developed using Microwave Studio for numerical analysis. Good agreement between computed and measured results is shown for both copper and CNT antennas, and their performance is compared. The CNT antenna shows stable gain and radiation patterns over the 24 to 34 GHz frequency range. The dispersion characteristics of the CNT antenna show its suitability for wideband communication systems. Using a quarter-wave matched T-junction as feed network, a two-element CNT antenna array is realized and the performance is compared with a copper antenna. The housing effect on the performance of the CNT antenna is shown to be much lower than for the copper antenna

Multiwall Carbon Nanotube-Epoxy Composites With High Shielding Effectiveness for Aeronautic Applications

Using mass-produced multiwall carbon nanotubes (MWCNTs) from different providers, we have fabricated nanocomposites with high and nearly constant shielding effectiveness (SE) over a wide frequency range up to 26.5 GHz. The MWCNT weight fraction and sample thickness were lower than 10% and 2 mm, respectively. The fabrication process and percolation curves are described. A high dc conductivity of 239.1 S/m was achieved at an MWCNT loading of only 8% by weight. The effect of aspect ratio on shielding performance is addressed. By comparing the measured SE of the composite with predictions from a model of the measurement setup using Microwave Studio, the effective conductivity of the nanocomposite was determined. Since the thickness is very important for shielding analysis, the SE/unit thickness diagram was calculated by using the effective parameters of samples. The results were verified experimentally by measuring the SE of samples with different thicknesses

The IMPROVE guidelines (Ischaemia Models: Procedural Refinements Of in Vivo Experiments)

Most in vivo models of ischaemic stroke target the middle cerebral artery and a spectrum of stroke severities, from mild to substantial, can be achieved. This review describes opportunities to improve the in vivo modelling of ischaemic stroke and animal welfare. It provides a number of recommendations to minimise the level of severity in the most common rodent models of middle cerebral artery occlusion, while sustaining or improving the scientific outcomes. The recommendations cover basic requirements pre-surgery, selecting the most appropriate anaesthetic and analgesic regimen, as well as intraoperative and post-operative care. The aim is to provide support for researchers and animal care staff to refine their procedures and practices, and implement small incremental changes to improve the welfare of the animals used and to answer the scientific question under investigation. All recommendations are recapitulated in a summary poster (see supplementary information)

A global perspective on the trophic geography of sharks

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.This research was conducted as part of C.S.B.’s Ph.D dissertation, which was funded by the University of Southampton and NERC (NE/L50161X/1), and through a NERC Grant-in-Kind from the Life Sciences Mass Spectrometry Facility (LSMSF; EK267-03/16). We thank A. Bates, D. Sims, F. Neat, R. McGill and J. Newton for their analytical contributions and comments on the manuscripts.Peer reviewe

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake