Potential Weight Benefits of IM7/8552 Hybrid Thin-Ply Composites for Aircraft Structures

Composite materials have increasingly been used for aerospace applications due to improved performance and reduced weight compared to their metallic counterparts. Inclusion of thin-ply material, plies with cured thickness half or less than standard-ply composites, have potential to improve performance and reduce structural weight further. The effect of thin-ply material on the weight of aircraft structure was investigated by examining wing cover weight reduction. To minimize the effects on manufacturing due to using thin plies, hybrid laminates were examined that used thin 45-degree plies to replace their standard-ply counterparts in laminates. Compression after impact (CAI) tests were conducted to examine the possible weight savings that could be gained by increasing the design allowables that were used to size the wing upper cover of a semi-span test article. A large increase in CAI strength was observed for quasi-isotropic hybrid laminates, whereas less improvement was seen for hard hybrid laminates such as found in the wing cover. For laminates design by CAI strength, weight savings of about 13% were found using the hybrid hard laminates compared to the standard-ply laminates. Whether similar weight savings could be expected for structure sized using tension after impact allowables will have to be investigated further. Notched specimens were tested to examine possible weight savings using hybrid laminates in regions that are sized using discrete source damage requirements. As expected, the hybrid laminate had marginal improvements over the standard-ply laminate for compression with a notch present. The hybrid laminate, however, exhibited about 20% lower strength than the standard-ply laminate counterpart for tension with a notch. The failure mode of the hybrid specimens was a brittle, self-similar crack, which differs from the standard-ply specimens that failed by significant amounts of delamination and fiber splitting. In light of the apparent reduction in notched tensile strength, additional investigation is required to assess the use of hybrid laminates for areas containing discrete source damage, and their effect on weight of such regions

Servizi pubblici locali

Il saggio delinea la parabola del servizio pubblico locale che, dalle municipalizzazioni di inizio 900, giunge sino ai giorni nostri. E, nell'attuale quadro di instabilit\ue0 della disciplina dei servizi pubblici locali, cerca di cogliere i principi e le linee fondamentali del sistema

Mutations in the bovine prolactin receptor (PRLR) gene: allele and haplotype frequencies in the Reggiana cattle breed

AbstractProlactin receptor (PRLR) is a member of the cytokine receptor superfamily. PRLR exerts its functions binding three types of ligands (prolactin, placental lactogen and growth hormone) invol..

Optical monitoring of gamma-ray source fields

The three gamma-ray burst source fields GBS1028+46, GBS1205+24, and GBS2252-03 have been monitored for transient optical emission for a combined total of 52 hours. No optical events were seen. The limiting magnitude for the search was M sub V = 15.8 longer and M sub V = 17.0 for 6.0 s or longer

Characterization of IM7/8552 Thin-Ply and Hybrid Thin-Ply Composites

Composite materials have increasingly been used for aerospace applications due to improved performance and reduced weight compared to their metallic counterparts. Inclusion of thin-ply material, plies with cured thickness half or less than standard composites, have potential to improve performance and reduce structural weight. Limited characterization of thin-ply IM7/8552 material in 30 and 70 grams per square meter fiber areal weights has been carried out using a series of selected American Society for Testing and Materials (ASTM) tests. Tests included unnotched tension, unnotched compression, v-notched rail shear, open-hole tension, and open-hole compression. Unidirectional, cross-ply, quasiisotropic and hybrid hard laminates were included in the study, and were compared to standard-ply laminates. Properties compared include fiber volume, laminate moduli, and failure strength, with failure modes also being examined. The thin-ply specimens exhibited similar or superior performance to standard ply laminates in many of the cases compared. Improvements in strength for laminates containing thin-ply material were seen for unidirectional laminates under unnotched tension, quasi-isotropic laminates under unnotched tension and compression, and hard laminates under open hole tension. Additional investigation is required to determine appropriate ply stacking rules for hybrids of thin and standard plies to avoid undesirable failure modes such as axial splitting. However, the observed performance improvements demonstrated by the conducted ASTM tests of hybrid thin-ply hard laminates could have benefits for improved structural weight in aircraft

Liceit\ue0 legittimit\ue0 e responsabilit\ue0 dell'amministrazione

Lo studio ha ad oggetto il problema dei danni generati dall'amministrazione nel legittimo perseguimento degli interessi della collettivit\ue0. Sono questi danni che devono essere lasciati "l\ue0 dove cadono" ovvero devono essere riparati? Le conseguenze dannose della funzione pubblica devono essere, in altri termini, sopportate dai singoli su cui casualmente incidono o devono essere redristribuite su tutta la collettivit\ue0 che si avvantaggia delle attivit\ue0 pubbliche? La risposta viene ricercata, da un lato, muovendo dai diritti concretamente lesi, onde verificare se la protezione ad essi assicurata rispetto ad interferenze pubbliche comprenda anche le interferenze lecite e, dall'altro, muovendo dai principi (di correttezza, di buona fede, di non abuso e, in ultima istanza, di proporzionalit\ue0) che governano le scelte pubbliche. In questo quadro la ricerca conduce ad evidenziare una duplice risposta al problema: una vera e propria responsabilit\ue0 da atto lecito, per le compressioni dei diritti fondamentali nel loro nucleo essenziale, e un principio di compensazione, quale regola di proporzione intesa a ristabilire l'equilibrio turbato dall'azione amministrativa che comprima le posizioni individuali senza concretarsi in una lesione dei diritti fondamentali nella loro essenzialit\ue0

St John’s wort (Hypericum perforatum) products – an assessment of their authenticity and quality

St John’s wort products (Hypericum perforatum L.) are widely available for sale in many countries including the UK via the internet. In the UK, these products are required to hold either a marketing authorisation or Traditional herbal registration (THR) to be sold legally. The THR and other regulatory schemes help to ensure product safety and quality providing an example of best practice but there is a risk if both regulated and un-regulated products continue to be available to consumers. Aims: the project is embedded in a larger study aiming to investigate the quality of different herbal medicinal products along diverse value chains. Here we focus on a comparison of the quality of the finished products and assess phytochemical variation between registered products (THRs) and products obtained from the market without any registration. Methods: 47 commercial products (granulated powders and extracts) were sourced from different suppliers. We analysed these samples using high performance thin layer chromatography (HPTLC) and 1H-NMR spectroscopy coupled with multi-variate analysis software following a method previously developed by our group. Results: the consistency of the products varies significantly. Adulteration of the products (36%), possibly with other Hypericum species obtained from China or use of chemically distinct H. perforatum cultivars or chemotypes, and adulteration of the products (19%) with food dyes (tartrazine, amaranth, brilliant blue, sunset yellow) were the principle findings of this study. Conclusions: There is significant compositional variation among commercial finished products and two main causative quality problems were identified as adulteration by incorrect species or adulteration with food dyes. Generally, food supplements and unlicensed products were found to be of poorer quality than the regulated ones like registered THRs

Source parameters of the 11 June 1909, Lambesc (Provence, southeastern France) earthquake: a reappraisal based on macroseismic, seismological and geodetic observations

Destructive earthquakes are rare in France yet pose a sizable seismic hazard, especially when critical infrastructures are concerned. Only a few destructive events have occurred within the instrumental period, the most important being the 11 June 1909, Lambesc (Provence) earthquake. With a magnitude estimated at 6.2 [Rothé, 1942], the event was recorded by 30 observatories and produced intensity IX effects in the epicentral area, ~30 km north of Marseille. We collected 30 seismograms, leveling data and earthquake intensities to assess the magnitude and possibly the focal mechanism of this event. Following this multidisciplinary approach, we propose a source model where all relevant parameters are constrained by at least two of the input datasets. Our reappraisal of the seismological data yielded Mw 5.8-6.1 (6.0 preferred) and Ms 6.0, consistent with the magnitude from intensity data (Me 5.8) and with constraints derived from modeling of coseismic elevation changes. Hence, we found the Lambesc earthquake to have been somewhat smaller than previously reported. Our datasets also constrain the geometry and kinematics of faulting, suggesting that the earthquake was generated by reverse-right lateral slip on a WNW-striking, steeply north-dipping fault beneath the western part of the Trévaresse fold. This result suggests that the fold, located in front of the Lubéron thrust, plays a significant role in the region’s recent tectonic evolution. The sense of slip obtained for the 1909 rupture also agrees with the regional stress field obtained from earthquake focal mechanisms and microtectonic data as well as recent GPS data

Big fish eat small fish: implications for food chain length?

Food chains in the pelagic zones of oceans and lakes are longer than in terrestrial ecosystems. The perception of the pelagic food web has become increasingly complex by progressing from a linear food chain (phytoplankton – crustacean zooplankton – planktivorous fish – predatory fish) to a food web because of an increasing appreciation of microbial trophic pathways, side-tracks by gelatinous zooplankton and a high prevalence of omnivory. The range of predator:prey size ratios by far exceeds the traditionally assumed range of 10:1 to 100:1, from almost equal length to 105:1. The size ratios between primary consumers and top predators are 3½ orders of magnitude bigger in pelagic than in terrestrial food webs. Comparisons between different pelagic ecosystems support ecosystem size as an important factor regulating the maximal trophic level, while energy limitation of the number of trophic levels is less well supported. An almost 1:1 relationship between ingestion by predators and prey mortality and a better chemical match between primary producer and herbivore biomass are further distinctive features of the pelagic food web whose role in explaining the higher number of trophic levels in pelagic systems needs further examination

Chrysanthemum species used as food and medicine: Understanding quality differences on the global market

Background Chrysanthemum flowers [Ch. x morifolium (Ramat.) Hemsl. and Ch. indicum L.] are a globally used and pharmacologically interesting botanical drug, however, with variable product quality. Objective We aim at understanding the chemical variability of primary material available commercially based on different origins and associated quality problems like contamination with heavy metals. This needs to be assessed in the context of the current regulations for this botanical drug and associated problems. Material and Methods 15 C. indicum L. and 50 C. x morifolium (Ramat.) Hemsl., including a range of geographical cultivars recognized in China, samples from the USA, Europe and China were analyzed using High Performance Thin Layer Chromatography (HPTLC) to compare their general chemical profile. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) was used to quantify heavy metal contamination. Results The: HPTLC fingerprints of C. indicum samples are clearly distinguishable from C. x morifolium. Fingerprints of samples from the same cultivars collected from markets in different countries (USA and China) show different patterns. Large variance of fingerprints within each cultivar group was observed. The heavy metal analysis showed excessive amounts of some harmful heavy metal in some commercial products with excessive cadmium being the most frequent problem. Conclusions The Chinese medicinal cultivars vary. Differences between samples sourced from the USA and China might be ascribable to geographical factors (e.g. soil composition), degradation during transport/storage or adulteration, but geographical differences should also be taken into account. Importantly, a much more detailed definition of the drug are needed for better quality control. In addition, with continuous contamination problem observed, a more widespread regulation is an essential requirement for better quality