Spectroscopic and Microscopic Characterization of Microbial Biofouling on Aircraft Fuel Tanks

Full text also available at: Europe PMC - https://europepmc.org/article/MED/38319653Avoiding microbial contamination and biofilm formation on the surfaces of aircraft fuel tanks is a major challenge in the aviation industry. The inevitable presence of water in fuel systems and nutrients provided by the fuel makes an ideal environment for bacteria, fungi, and yeast to grow. Understanding how microbes grow on different fuel tank materials is the first step to control biofilm formation in aviation fuel systems. In this study, biofilms of Pseudomonas putida, a model Gram-negative bacterium previously found in aircraft fuel tanks, were characterized on aluminum 7075-T6 surfaces, which is an alloy used by the aviation industry due to favorable properties including high strength and fatigue resistance. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) showed that extracellular polymeric substances (EPS) produced by P. putida were important components of biofilms with a likely role in biofilm stability and adhesion to the surfaces. EDX analysis showed that the proportion of phosphorus with respect to nitrogen is higher in the EPS than in the bacterial cells. Additionally, different morphologies in biofilm formation were observed in the fuel phase compared to the water phase. Micro-Fourier transform infrared spectroscopy (micro-FTIR) analysis suggested that phosphoryl and carboxyl functional groups are fundamental for the irreversible attachment between the EPS of bacteria and the aluminum surface, by the formation of hydrogen bonds and inner-sphere complexes between the macromolecules and the aluminum surface. Based on the hypothesis that nucleic acids (particularly DNA) are an important component of EPS in P. putida biofilms, the impact of degrading extracellular DNA was tested. Treatment with the enzyme DNase I affected both water and fuel phase biofilms─with the cell structure disrupted in the aqueous phase, but cells remained attached to the aluminum coupons.InnovateUK and Airbus Operations Ltd., within the project “Fuel Architecture and Systems Technology (FAST)”, Project reference 113161 (TS/R008132/1). A.D.M. acknowledges funding from the UK Engineering and Physical Sciences Research Council (EPSRC) DTP scholarship (project reference: 2748843

Understanding Communication of Sustainability Reporting: Application of Symbolic Convergence Theory (SCT)

The purpose of this paper is to investigate the nature of rhetoric and rhetorical strategies that are implicit in the standalone sustainability reporting of the top 24 companies of the Fortune 500 Global. We adopt Bormann’s (Q J Speech 58(4):396–407, 1972) SCT framework to study the rhetorical situation and how corporate sustainability reporting (CSR) messages can be communicated to the audience (public). The SCT concepts in the sustainability reporting’s communication are subject to different types of legitimacy strategies that are used by corporations as a validity and legitimacy claim in the reports. A content analysis has been conducted and structural coding schemes have been developed based on the literature. The schemes are applied to the SCT model which recognizes the symbolic convergent processes of fantasy among communicators in a Society. The study reveals that most of the sample companies communicate fantasy type and rhetorical vision in their corporate sustainability reporting. However, the disclosure or messages are different across locations and other taxonomies of the SCT framework. This study contributes to the current CSR literature about how symbolic or fantasy understandings can be interpreted by the users. It also discusses the persuasion styles that are adopted by the companies for communication purposes. This study is the theoretical extension of the SCT. Researchers may be interested in further investigating other online communication paths, such as human rights reports and director’s reports

Na+,K+-ATPase is the putative membrane receptor of hormone ouabain

At 10 nM, ouabain elicits changes in cell contacts, which are independent and usually in opposite direction to effects occurring at µM levels, suggesting that these depend on entirely different mechanisms.1 However, this does not discard the possibility that in both instances ouabain would act on the same receptor. We demonstrate that such is the case by comparing the response of wild and ouabain-resistant MDCK cells on a very special type of cell contact, the tight junction (TJ)

Uterine artery impedance during puerperium in normotensive and chronic hypertensive pregnant women

Purpose: The present study compared the Doppler flow pulsatility indices (PI) in the uterine arteries (UtA) during the puerperium between healthy women and those with stage-1 essential hypertension who had uncomplicated pregnancies and delivered by elective caesarean section. The change in the mean arterial pressure (MAP) and body mass index (BMI) over time was also assessed. Methods: A longitudinal and prospective study was performed in singleton pregnancies of 28 normotensive (NT) and 24 hypertensive (HT) women. The UtA-PI was measured immediately before caesarean section (time 0) and at 1 week (time 1) and 4 weeks (time 2) postpartum. The presence or absence of early diastolic notches was recorded. The change in the MAP, BMI, and UtA-PI over time and between the two populations was modelled through multivariate linear regression using the generalised least squares. Results: In both groups, the UtA-PI significantly increased from time 0 to time 1 (p\0.05) and time 2 (p\0.05). Stage-1 hypertension did not change the trend but did increase the UtA-PI magnitude (p\0.05). The presence of uterine artery notching increased over time, from 6 to 98 %, in both groups (p\0.001); however, in the HT group, at time 1, the majority of women exhibited positive notching [92 % (HT) vs 57 % (NT), p = 0.013]. Conclusions: Chronic stage-1 hypertensive women with normal pregnancy outcomes exhibited a progressively increasing postpartum UtA impedance. This trend also occurred in normotensive women, albeit at a significantly lower magnitude. </p