An experimental platform for surface embedded SMAs in morphing applications

This article will address the modeling and control of surface embedded shape memory alloys (SMAs) for the camber modification of a hybrid morphing airfoil. An analytical model will be derived. The results of this models will be discussed and compared to the experiments. The advantages of this modeling approach will be highlighted and alternatives will be briefly revisited. This discussion will figure into the utility of these models in the sizing of a full scale prototype of a SMA actuated active trailing edge of an airfoil. Throughout this article the prototype specifications are detailed and the design choices will be discussed. Performance improvements stemming from the inherent nature of the SMAs will be analyzed. It will be shown in this article that through the use of forced convection the overall cycle time can be reduced

A combined smart-materials approach for next-generation airfoils

This article will present a morphing wing actuated using both surface embedded Shape memory alloys (SMAs) and trailing edge Macro-fiber composites (MFCs). This combination enables the airfoil to simultaneously achieve large scale deformations at low frequencies as well as rapid actuation with a limited amount of displacement. Thereby not only can the shape of the airfoil be optimized in function of the current mission profile but also the shear layer can be influenced. Each actuator is modelled using both a finite element and/or an analytical model and the results will be verified experimentally

The tree that hides the forest: Cryptic diversity and phylogenetic relationships in the Palaearctic vector Obsoletus/Scoticus Complex (Diptera: Ceratopogonidae) at the European level

Background: Culicoides obsoletus is an abundant and widely distributed Holarctic biting midge species, involved in the transmission of bluetongue virus (BTV) and Schmallenberg virus (SBV) to wild and domestic ruminants. Females of this vector species are often reported jointly with two morphologically very close species, C. scoticus and C. montanus, forming the Obsoletus/Scoticus Complex. Recently, cryptic diversity within C. obsoletus was reported in geographically distant sites. Clear delineation of species and characterization of genetic variability is mandatory to revise their taxonomic status and assess the vector role of each taxonomic entity. Our objectives were to characterize and map the cryptic diversity within the Obsoletus/Scoticus Complex. Methods: Portion of the cox1 mitochondrial gene of 3763 individuals belonging to the Obsoletus/Scoticus Complex was sequenced. Populations from 20 countries along a Palaearctic Mediterranean transect covering Scandinavia to Canary islands (North to South) and Canary islands to Turkey (West to East) were included. Genetic diversity based on cox1 barcoding was supported by 16S rDNA mitochondrial gene sequences and a gene coding for ribosomal 28S rDNA. Species delimitation using a multi-marker methodology was used to revise the current taxonomic scheme of the Obsoletus/Scoticus Complex. Results: Our analysis showed the existence of three phylogenetic clades (C. obsoletus clade O2, C. obsoletus clade dark and one not yet named and identified) within C. obsoletus. These analyses also revealed two intra-specific clades within C. scoticus and raised questions about the taxonomic status of C. montanus. Conclusions: To our knowledge, our study provides the first genetic characterization of the Obsoletus/Scoticus Complex on a large geographical scale and allows a revision of the current taxonomic classification for an important group of vector species of livestock viruses in the Palaearctic region.[Figure not available: See fulltext.

Cancer effects of formaldehyde: a proposal for an indoor air guideline value

Formaldehyde is a ubiquitous indoor air pollutant that is classified as “Carcinogenic to humans (Group 1)” (IARC, Formaldehyde, 2-butoxyethanol and 1-tert-butoxypropanol-2-ol. IARC monographs on the evaluation of carcinogenic risks to humans, vol 88. World Health Organization, Lyon, pp 39–325, 2006). For nasal cancer in rats, the exposure–response relationship is highly non-linear, supporting a no-observed-adverse-effect level (NOAEL) that allows setting a guideline value. Epidemiological studies reported no increased incidence of nasopharyngeal cancer in humans below a mean level of 1 ppm and peak levels below 4 ppm, consistent with results from rat studies. Rat studies indicate that cytotoxicity-induced cell proliferation (NOAEL at 1 ppm) is a key mechanism in development of nasal cancer. However, the linear unit risk approach that is based on conservative (“worst-case”) considerations is also used for risk characterization of formaldehyde exposures. Lymphohematopoietic malignancies are not observed consistently in animal studies and if caused by formaldehyde in humans, they are high-dose phenomenons with non-linear exposure–response relationships. Apparently, these diseases are not reported in epidemiological studies at peak exposures below 2 ppm and average exposures below 0.5 ppm. At the similar airborne exposure levels in rodents, the nasal cancer effect is much more prominent than lymphohematopoietic malignancies. Thus, prevention of nasal cancer is considered to prevent lymphohematopoietic malignancies. Departing from the rat studies, the guideline value of the WHO (Air quality guidelines for Europe, 2nd edn. World Health Organization, Regional Office for Europe, Copenhagen, pp 87–91, 2000), 0.08 ppm (0.1 mg m−3) formaldehyde, is considered preventive of carcinogenic effects in compliance with epidemiological findings

Identifying an indoor air exposure limit for formaldehyde considering both irritation and cancer hazards

Formaldehyde is a well-studied chemical and effects from inhalation exposures have been extensively characterized in numerous controlled studies with human volunteers, including asthmatics and other sensitive individuals, which provide a rich database on exposure concentrations that can reliably produce the symptoms of sensory irritation. Although individuals can differ in their sensitivity to odor and eye irritation, the majority of authoritative reviews of the formaldehyde literature have concluded that an air concentration of 0.3 ppm will provide protection from eye irritation for virtually everyone. A weight of evidence-based formaldehyde exposure limit of 0.1 ppm (100 ppb) is recommended as an indoor air level for all individuals for odor detection and sensory irritation. It has recently been suggested by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), and the US Environmental Protection Agency (US EPA) that formaldehyde is causally associated with nasopharyngeal cancer (NPC) and leukemia. This has led US EPA to conclude that irritation is not the most sensitive toxic endpoint and that carcinogenicity should dictate how to establish exposure limits for formaldehyde. In this review, a number of lines of reasoning and substantial scientific evidence are described and discussed, which leads to a conclusion that neither point of contact nor systemic effects of any type, including NPC or leukemia, are causally associated with exposure to formaldehyde. This conclusion supports the view that the equivocal epidemiology studies that suggest otherwise are almost certainly flawed by identified or yet to be unidentified confounding variables. Thus, this assessment concludes that a formaldehyde indoor air limit of 0.1 ppm should protect even particularly susceptible individuals from both irritation effects and any potential cancer hazard

1-D hydrogen-bonded organization of hexanuclear {3d-4f-5d} complexes: evidence for slow relaxation of the magnetization for [{L<SUP>Me2</SUP>Ni(H<SUB>2</SUB>O)Ln(H<SUB>2</SUB>O)<SUB>4.5</SUB>}<SUB>2</SUB>{W(CN)<SUB>8</SUB> }<SUB>2</SUB>] with Ln=Tb and Dy

Heterometallic {3d-4f-5d} aggregates with formula [{LMe2Ni(H2O)Ln(H2O)4.5}2{W(CN)8}2 ]&#183;15H2O, (LMe2 stands for N,N'-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato) Schiff-base ligand) with Ln=Gd, Tb, Dy, have been obtained by reacting bimetallic [LMe2Ni(H2O)2Ln(NO3)3] and Cs3{W(CN)8} in H2O. The hexanuclear complexes are organized in 1-D arrays by means of hydrogen bonds established between the solvent molecules coordinated to Ln and the CN ligands of an octacyanometallate moiety. The X-ray structure was solved for the Tb derivative. Magnetic behavior indicates ferromagnetic {W-Ni} and {Ni-Ln} interactions (JNiW=18.5 cm-1, JNiGd=1.85 cm-1) as well as ferromagnetic intermolecular interactions mediated by the H-bonds. Dynamic magnetic susceptibility studies reveal slow magnetic relaxation processes for the Tb and Dy derivatives, suggesting SMM type behavior for these compounds

An Experimental Platform for Surface Embedded SMAs in Morphing Applications

This article will address the modeling and control of surface embedded shape memory alloys (SMAs) for the camber modification of a hybrid morphing airfoil. An analytical model will be derived. The results of this models will be discussed and compared to the experiments. The advantages of this modeling approach will be highlighted and alternatives will be briefly revisited. This discussion will figure into the utility of these models in the sizing of a full scale prototype of a SMA actuated active trailing edge of an airfoil. Throughout this article the prototype specifications are detailed and the design choices will be discussed. Performance improvements stemming from the inherent nature of the SMAs will be analyzed. It will be shown in this article that through the use of forced convection the overall cycle time can be reduced

Enhanced Ion Anisotropy by Non-Conventional Coordination Geometry: Single-Chain Magnet behavior for a [{FeIIL}2{NbIV(CN)8}] Helical Chain Compound Designed with Heptacoordinate FeII.

International audienc

Supramolecular open-framework architectures based on dicarboxylate H-bond acceptors and polytopic cations with three/four N-H+ donor units

International audienceSupramolecular assemblages based on anionic H-acceptors and cationic H-donors have been envisioned to elaborate open frameworks maintained by ionic H-bonds. Combinations of di-anionic chloranilate (CA2-), oxalate (Ox2-), or terephthalate (BDC2-) and trisimidazolium or tetrapyridinium derivatives (three and four N-H+ donors, respectively) yielded five architectures of formulae [(H3TrIB)(CA)1.5[middle dot]2DMF[middle dot]2.5H2O] (1), [(H4Tetrapy)(CA)2[middle dot]3DMF] (2), [(H3TrIB)(HOx)(Ox)[middle dot]5H2O] (3), [(H4Tetrapy)(Ox)2[middle dot]5H2O] (4), and [(H4Tetrapy)(BDC)2(H2O)[middle dot]1DMF[middle dot]3H2O] (5) (with TrIB = 1,3,5-trisimidazolylbenzene and Tetrapy = tetrakis[(pyridine-4-yloxy)methyl]methane). Four of these, i.e.1, 2, 4 and 5, show an open framework. Their assembling patterns and framework dimensionalities are mainly governed by the chemical features of the cation. 1D (3) and 2D (1) networks are found with [H3TrIB]3+, whereas 3D diamond-type networks (2, 4, 5) are systematically formed with [H4Tetrapy]4+. While the individual adamantanoid cages exhibit large voids in all 3D structures, net catenations (with a total degree of interpenetration up to 19) reduce the potential porosities of the solids to 17-32%. The largest solvent accessible void (42%) is found for the 2D supramolecular organization of 1, for which net interpenetration does not take place. Crystal structures for all five architectures are reported. Framework robustness upon guest departure and gas sorption properties have been explored for materials 1 and 2 with the highest potential accessible voids

Effect of Ligand Substitution around the Dy-III on the SMM Properties of Dual-Luminescent Zn-Dy and Zn-Dy-Zn Complexes with Large Anisotropy Energy Barriers: A Combined Theoretical and Experimental Magnetostructural Study

The new dinuclear (ZnDyIII)-Dy-II and trinuclear (ZnDyIII)-Dy-II-Zn-II complexes of formula [(LZnBrDy(ovan) (NO3)(H2O)](H2O)center dot 0.5(MeOH) (1) and [((LZnBr)-Zn-1)(2)Dy(MeOH)(2)](ClO4) (3) (L and L-1 are the dideprotonated forms of the N,N'-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato and 2-{(E)-[(3-{[(2E,3E)-3-(hydroxyimino)butan-2-ylidene ]amino}-2,2-dimethylpropyl)imino]methyl}-6-methoxyphenol Schiff base compartmental ligands, respectively) have been prepared and magnetostructurally characterized. The X-ray structure of 1 indicates that the Dy-III ion exhibits a DyO9 coordination sphere, which is made from four O atoms coming from the compartmental ligand (two methoxy terminal groups and two phenoxido bridging groups connecting Zn-II and Dy-III ions), other four atoms belonging to the chelating nitrato and ovanillin ligands, and the last one coming to the coordinated water molecule. The structure of 3 shows the central Dy-III ion surrounded by two L1Zn units, so that the Dy-III and Zn-II ions are linked by phenoxido/oximato bridging groups. The Dy ion is eight-coordinated by the six O atoms afforded by two L1 ligands and two O atoms coming from two methanol molecules. Alternating current (AC) dynamic magnetic measurements of 1, 3, and the previously reported dinuclear [LZnClDy(thd)(2)] (2) complex (where thd = 2,2,6,6-tetramethyl-3,5-heptanedionato ligand) indicate single molecule magnet (SMM) behavior for all these complexes with large thermal energy barriers for the reversal of the magnetization and butterfly-shaped hysteresis loops at 2 K. Ab initio calculations on 1-3 show a pure Ising ground state for all of them, which induces almost completely suppressed quantum tunnelling magnetization (QTM), and thermally assisted quantum tunnelling magnetization (TA-QTM) relaxations via the first excited Kramers doublet, leading to large energy barriers, thus supporting the observation of SMM behavior. The comparison between the experimental and theoretical magnetostructural data for 13 has allowed us to draw some conclusions about the influence of ligand substitution around the Dy-III on the SMM properties. Finally, these SMMs exhibit metal- and ligand-centered dual emissions in the visible region, and, therefore, they can be considered as magnetoluminescent bifunctional molecular materials