Dynamic buckling of composite mast panels of sail ships

Composite materials are becoming more and more popular, even for large ship and offshore structures. They offer lightweight and adaptable strength and stiffness properties. In case of slender structures, where buckling is the governing limit state, such features are valuable and allow designing high performance assemblies like racing crafts as well as very large sail ships. The case of composite masts of sail ships is rather interesting as, on the one hand, relatively large, stiff but light structures are needed and, on the other hand, their reliability is crucial for ship safety. Hence, complete understanding of structural behaviour is essential to avoid too large safety factors. Indeed, such case is also the paradigm of the dynamic buckling behaviour of slender columns structures, pointing out differences between the widely used quasi-static design approach and the more realistic time domain simulations. An earlier work studied the dynamic buckling behaviour of a metallic mast. Now, the study has been extended to the much more complex case of composite masts, showing some variations due to anisotropic material properties and specific weight values different by an order of magnitude. Comprehensive description of the dynamic buckling of a typical composite mast panel is outlined in this paper and compared to results from a previous investigation on aluminium alloy mast

Estimation of Long Term Bridge Pier Scour in Cohesive Soils at Maryland Bridges using EFA/SRICOS

Estimation of scour in cohesive soils is based on equations developed for non-cohesive soils that produce conservative scour estimates when applied to cohesive soils. This thesis evaluates the development of bridge pier scour via SRICOS, Scour in Cohesive Soils, a method to determine bridge pier scour depth in cohesive soils using results of the Erosion Function Apparatus (EFA) erosion tests and a hydrograph. Soil samples were collected from five Maryland sites; the EFA was used to measure their erosion rates and the SRICOS software predicted scour depths over a user-determined timespan. Predicted scour depths were compared to HEC-18 predicted pier scour depths. In all instances, the EFA/SRICOS method predicted less scour than the HEC-18 method, the current design standard. EFA/SRICOS represents an emerging re-thinking of erosion characterization to predict scour depths of cohesive soils at piers

Spotlight on the Compositional Quality of Probiotic Formulations Marketed Worldwide

On the worldwide market, a great number of probiotic formulations are available to consumers as drugs, dietary supplements, and functional foods. For exerting their beneficial effects on host health, these preparations should contain a sufficient amount of the indicated living microbes and be pathogen-free to be safe. Therefore, the contained microbial species and their amount until product expiry are required to be accurately reported on the labels. While commercial formulations licensed as drugs are subjected to rigorous quality controls, less stringent regulations are generally applied to preparations categorized as dietary supplements and functional foods. Many reports indicated that the content of several probiotic formulations does not always correspond to the label claims in terms of microbial identification, number of living organisms, and purity, highlighting the requirement for more stringent quality controls by manufacturers. The main focus of this review is to provide an in-depth overview of the microbiological quality of probiotic formulations commercialized worldwide. Many incongruences in the compositional quality of some probiotic formulations available on the worldwide market were highlighted. Even if manufacturers carry at least some of the responsibility for these inconsistencies, studies that analyze probiotic products should be conducted following recommended and up-to-date methodologies

Microbiological quality and resistance to an artificial gut environment of two probiotic formulations

The quality control of probiotic products is the focus of numerous organizations worldwide. Several studies have highlighted the poor microbiological quality of many commercial probiotic formulations in terms of the identity of the contained microorganisms, viability, and purity, thus precluding the expected health benefits and representing a potential health risk for consumers. In this paper, we analyzed the contents of two probiotic formulations, one composed of an encapsulated mixture of lactobacilli and bifidobacteria, and one by a lyophilized yeast. The microorganisms contained in the products were quantified and identified using up-to-date methodologies, such as MALDI-TOF MS and metagenomic analysis. Moreover, as acid and bile tolerance is included among the criteria used to select probiotic microorganisms, in vitro tests were performed to evaluate the behavior of the formulations in conditions mimicking the harsh gastric environment and the intestinal fluids. Our results indicate the high quality of the formulations in terms of the enumeration and identification of the contained organisms, as well as the absence of contaminants. Moreover, both products tolerated the acidic conditions well, with encapsulation providing further protection for the microorganisms. A good tolerance to the simulated artificial intestinal conditions was also evidenced for both preparations

FlhF, a signal recognition particle-like GTPase, is involved in the regulation of flagellar arrangement, motility behaviour and protein secretion in Bacillus cereus

Flagellar arrangement is a highly conserved feature within bacterial species. However, only a few genes regulating cell flagellation have been described in polar flagellate bacteria. This report demonstrates that the arrangement of flagella in the peritrichous flagellate Bacillus cereus is controlled by flhF. Disruption of flhF in B. cereus led to a reduction in the number of flagella from 10-12 to 1-3 filaments per cell in the insertion mutant MP06. Moreover, compared to the parental strain, MP06 exhibited: (i) shorter smooth swimming phases, causing reduced swimming motility but not affecting chemotaxis; (ii) complete inhibition of swarming motility, as differentiated swarm cells were never detected; (iii) an increased amount of extracellular proteins; and (iv) differential export of virulence determinants, such as haemolysin BL (HBL), phosphatidylcholine-preferring phospholipase C (PC-PLC) and non-haemolytic enterotoxin (NHE). Introduction of a plasmid harbouring flhF (pDGflhF) into MP06 completely restored the wild-type phenotype in the trans-complemented strain MP07. B. cereus flhF was found to constitute a monocistronic transcriptional unit and its overexpression did not produce abnormal features in the wild-type background. Characterization of a B. cereus mutant (MP05) carrying a partial flhF deletion indicated that the last C-terminal domain of FlhF is involved in protein export while not required for flagellar arrangement and motility behaviour. Taken together, these data suggest that B. cereus FlhF is a promising candidate for connecting diverse cellular functions, such as flagellar arrangement, motility behaviour, pattern of protein secretion and virulence phenotype

Contribution of Surfactin and SwrA to Flagellin Expression, Swimming, and Surface Motility in Bacillus subtilis.

Multicellular communities produced by Bacillus subtilis can adopt sliding or swarming to translocate over surfaces. While sliding is a flagellum-independent motility produced by the expansive forces in a growing colony, swarming requires flagellar functionality and is characterized by the appearance of hyperflagellated swarm cells that associate in bundles or rafts during movement. Previous work has shown that swarming by undomesticated B. subtilis strains requires swrA, a gene that upregulates the expression of flagellar genes and increases swimming motility, and surfactin, a lipopeptide biosurfactant that also facilitates sliding. Through an analysis of swrA(+) and swrA mutant laboratory strains with or without a mutation in sfp (a gene involved in surfactin production), we show that both swrA and surfactin upregulate the transcription of the flagellin gene and increase bacterial swimming. Surfactin also allows the nonswarming swrA mutant strain to efficiently colonize moist surfaces by sliding. Finally, we reconfirm the essential role of swrA in swarming and show that surfactin, which increases surface wettability, allows swrA(+) strains to produce swarm cells on media at low humidity

Comparative distribution of azithromycin in lung tissue of patients given oral daily doses of 500 and 1000 mg

OBJECTIVES: The administration of antibacterial agents should be optimized on the basis of their distribution to enhance drug exposure and obtain bacterial eradication. This study examines the pharmacokinetics of azithromycin in plasma, lung tissue and bronchial washing in patients after oral administration of 500 mg versus 1000 mg once daily for 3 days. PATIENTS AND METHODS: Samples of plasma, lung tissue and bronchial washing were obtained from a cohort of 48 patients during open-chest surgery for lung resection up to 204 h after the last drug dose, and assayed for antibiotic concentrations. RESULTS: Azithromycin was widely distributed within the lower respiratory tract and sustained levels of the drug were detectable at the last sampling time in lung tissue. Doubling the dose of the antibiotic resulted in a proportional increase in lung area under the curve (AUC, 1245.4 versus 2514.2 h x mg/kg) and peak tissue concentration (Cmax, 8.93 +/- 2.05 versus 18.6 +/- 2.20 mg/kg). The pharmacodynamic parameter AUC/MIC for susceptible and intermediate strains of Streptococcus pneumoniae (MICs 0.5 and 2 mg/L, respectively) increased after administration of the 1000 mg schedule compared with 500 mg (AUC/MIC0.5 2414 versus 1144 and AUC/MIC2 2112 versus 814.1 h x mg/kg, respectively) in pulmonary tissue. CONCLUSIONS: Lung exposure to azithromycin is increased proportionally by doubling the dose, which results in a predictable pharmacokinetic behaviour of the drug in the lower respiratory tract

Delivery Mode Shapes the Composition of the Lower Airways Microbiota in Newborns

Radical alterations in the human microbiota composition are well-known to be associated with many pathological conditions. If these aberrations are established at the time of birth, the risk of developing correlated pathologies throughout life is significantly increased. For this reason, all newborns should begin their lives with a proper microbiota in each body district. The present study aimed at demonstrating a correlation between the mode of delivery and the development of a well-balanced microbiota in the lower airways of newborns. 44 pregnant women were enrolled in this study. Microbiological comparative analysis was carried out on tracheobronchial secretions of babies born through vaginal delivery (VD) or caesarean section (CS). All samples showed the presence of bacterial DNA, regardless of the mode of delivery. No viable cultivable bacteria were isolated from the CS samples. On the contrary, VD allowed colonization of the lower airways by alive cultivable bacteria. The identification of bacterial species revealed that Lactobacillus spp. and Bacteroides vulgatus were the most common microorganisms in the lower airways of vaginally-delivered newborns. Data obtained from quantitative PCRs showed a significantly higher total bacterial load, as well as Firmicutes and Lactobacillus spp. amount, in VD samples than CS ones, while no statistically significant difference was found in Torque Teno Virus (TTV) load between samples. Taken together, our findings confirm the hypothesis that passage through the maternal vaginal canal determines more beneficial colonization of the lower airways in newborns

Characterization of a Bacillus cereus strain associated with a large feed-related outbreak of severe infection in pigs

Aims: Bacillus cereus is often responsible for foodborne diseases and both local and systemic infections in humans. Cases of infection in other mammals are rather rare. In this study, we report a B. cereus feed-related outbreak that caused the death of 6234 pigs in Italy. Methods and Results: Massive doses of a Gram-positive, spore-forming bacterium were recovered from the animal feed, faeces of survived pigs and intestinal content of dead ones. The B. cereus MM1 strain was identified by MALDI-TOF MS and typified by RAPD-PCR. The isolate was tested for the production of PC-PLC, proteases, hemolysins and biofilm, for motility, as well as for the presence of genes encoding tissue-degrading enzymes and toxins. Antimicrobial resistance and pathogenicity in Galleria mellonella larvae were also investigated. Our results show that the isolated B. cereus strain is swimming-proficient, produces PC-PLC, proteases, hemolysins, biofilm and carries many virulence genes. The strain shows high pathogenicity in G. mellonella larvae. Conclusions: The isolated B. cereus strain demonstrates an aggressive profile of pathogenicity and virulence, being able to produce a wide range of determinants potentially hazardous to pigs' health. Significance and Impact of Study: This study highlights the proficiency of B. cereus to behave as a devastating pathogen in swine if ingested at high doses and underlines that more stringent quality controls are needed for livestock feeds and supplements

Use of Saccharomyces boulardii CNCM I-745 as therapeutic strategy for prevention of nonsteroidal anti-inflammatory drug-induced intestinal injury

Background and Purpose: Nonsteroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse digestive effects. This study examined the protective effects of the probiotic Saccharomyces boulardii CNCM I-745 in a rat model of diclofenac-induced enteropathy. Experimental Approach: Enteropathy was induced in 40-week-old male rats by intragastric diclofenac (4 mg·kg−1 BID for 14 days). S. boulardii CNCM I-745 (3 g·kg−1 BID by oral gavage) was administered starting 14 days before (preventive protocol) or along with (curative protocol) diclofenac administration. Ileal damage, inflammation, barrier integrity, gut microbiota composition and toll-like receptors (TLRs)–nuclear factor κB (NF-κB) pathway were evaluated. Key Results: Diclofenac elicited intestinal damage, along with increments of myeloperoxidase, malondialdehyde, tumour necrosis factor and interleukin-1β, overexpression of TLR2/4, myeloid differentiation primary response 88 (Myd88) and NF-κB p65, increased faecal calprotectin and butyrate levels, and decreased blood haemoglobin levels, occludin and butyrate transporter monocarboxylate transporter 1 (MCT1) expression. In addition, diclofenac provoked a shift of bacterial taxa in both faecal and ileal samples. Treatment with S. boulardii CNCM I-745, in both preventive and curative protocols, counteracted the majority of these deleterious changes. Only preventive administration of the probiotic counteracted NSAID-induced decreased expression of MCT1 and increase in faecal butyrate levels. Occludin expression, after probiotic treatment, did not significantly change. Conclusions and Implications: Treatment with S. boulardii CNCM I-745 prevents diclofenac-induced enteropathy through anti-inflammatory and antioxidant activities. Such effects are likely to be related to increased tissue butyrate bioavailability, through an improvement of butyrate uptake by the enteric mucosa