Contribution to the mosquito fauna (Diptera, Culicidae) of Lika, central Croatia, with special reference to invasive species

This study of mosquitoes in Lika, geographically, geologically and climatically a very specific region, was conducted to gain insight into the composition and relative abundance of the mosquito fauna, as well as to check for the possible presence of invasive species. Sampling took place from July to September 2020. Mosquito larvae were captured from medium and small breeding sites using a 25 cm diameter net and a plastic dipper. Adult specimens were sampled in both urban and rural areas using CO2 baited CDC traps, CO2 baited BG Sentinel traps with BG Lure and human landing catch. The study was conducted at 69 sites. We collected 5,126 specimens (100 adults and 5,026 larvae) and demonstrated the presence of 16 mosquito species. CDC traps were almost five times more effective (quantity and quality) than BG Sentinel traps. The most common mosquito taxa caught in Lika were Culex pipiens complex (78.36% of all larvae) and Ae. geniculatus (30.26% of all adults). Both invasive mosquito species present in Croatia, Aedes albopictus and Ae. japonicus, were recorded, with Ae. albopictus being detected in Lika for the first time. Aedes japonicus was widespread, recorded in 23 localities. According to molecular analysis, only An. maculipennis s.s. was confirmed in the An. maculipennis complex. Within the Cx. pipiens complex, both Cx. pipiens biotypes, pipiens and molestus were confirmed together with one single hybrid specimen. Analysis of mosquito occurrence with regard to altitude shows that most samples and species were collected between 601 and 700 m a.s.l., although the Shannon evenness index and Hill’s index show the highest value in the range of 901 to 1140 m a.s.l. In this systematic study on the mosquito fauna in Lika, a significant species diversity, including invasive species, was found.

Tensile behaviour of hybrid fibre architectures of randomly oriented strands combined with laminate groups

In this work, the tensile behaviour of co-moulded hybrid fibre architectures of randomly oriented strands (carbon/PEEK) combined with laminate groups (cross-ply, angle-ply and quasi-isotropic) is studied. The effects of varying the thickness of the laminate group relative to that of randomly oriented strands, stacking sequence of the architectures within a hybrid specimen, and the ply stacking sequences within the laminate group are quantified. Processing benefits of hybridization such as reduction in warpage and strand waviness are discussed. The tensile behaviour of hybrid fibre architectures is quantified and compared with that of randomly oriented strand specimens, base laminate groups and aluminum 7075. In addition, tensile failure modes have been investigated. Significant improvements in the mechanical properties of randomly oriented strands are observed with small proportions of laminate groups in the specimen. In addition, hybrid fibre architectures exhibit a positive synergy or a positive deviation from the rule-of-mixtures in the overall stiffness and strength behaviour when stacked in specific configurations, despite the same fundamental fibre type and matrix system.

Influencing Intermetallic Layers of Hot Stamped Steel for Adhesively Bonded Plastic Metal Hybrids

Hot stamping of high strength steel parts is an established way to realize today ́s structural lightweight components in car bodies through sheet thickness reduction. The steel typically used for hot stamping is a boron-manganese 22MnB5 steel reaching up to 1,900 MPa in strength. New boron-manganese alloys achieving higher strength are expected to be developed, generating challenges for the manufacturing process by means of formability. Thus, a further reduction of steel thickness resulting in lighter components is not expected. Hybrid lightweight design approaches aim at weight reduction by reducing steel thickness and applying fiber-reinforced plastics (FRP) to regain structural stiffness and strength. The use of residual heat remaining from the hot stamping process allows to activate adhesives to bond FRP to hot stamped steel. The performances of adhesive bonds depend strongly on surface characteristics. To avoid scaling and decarburization during the heating process several coatings for hot stamped steels are used forming intermetallic layers through heat treatment. The most common coating in today’s automotive application is an Al-Si coating. Thus, the overall performance of the adhesive bonded hot stamped metal polymer hybrid is not only depending on adhesives performance but also strongly on the hot stamped steel’s coating performance. In this paper, the characteristics of hot stamped steel 22MnB5 Al-Si coating are investigated with regard to adhesion performance. Therefore, hot stamped specimens are manufactured under realistic industrial conditions investigating the influence of furnace temperature and dwell time on the overall coating and intermetallic layers of Al-Si coating. The specimens are investigated with respect to Al-Si coating thickness, lap shear strength of hybrid specimen and tensile strength of hot stamped steel demonstrating the dependency of the overall hybrid specimen performance from the coating performance.

Discovery of a rare hybrid specimen known as Maria’s bird of paradise at the Staatliches Naturhistorisches Museum in Braunschweig

The discovery of a rare hybrid specimen of Maria’s bird of paradise (Paradisaeamaria, i.e., P.guilielmi × P.raggianaaugustaevictoriae) in the ornithological collection of the Staatliches Naturhistorisches Museum in Braunschweig (SNMB) is reported. Until today only six male specimens (deposited in the natural history museums in Berlin and New York) and presumably one female have been identified in collections world-wide. The male specimen in Braunschweig corresponds well in its plumage colouration with an historical illustration and photographs of the original type specimen from the 19th century housed at the Berlin collection. It shows intermediate characteristics between both parental species, viz. the Emperor bird of paradise (P.guilielmi) and the Raggiana bird of paradise (P.raggianaaugustaevictoriae). In addition, we try to elucidate the circumstances how this rare specimen of hybrid origin, which formerly belonged to the natural history collection of the factory owner Walter Behrens from Bad Harzburg, came to the SNMB. Our unexpected discovery highlights the importance to maintain, support and study also smaller private natural history collections, since they may house historical voucher specimens of high scientific value.

COMPRESSIVE STRENGTH OF CONCRETE WITH FIBRES AT ELEVATED TEMPERATURE

Concrete, when exposed to high temperature, can cause spalling, cracking, and severe damage, which could lead to a sudden collapse of a building. One of the solutions for overcoming this weakness of concrete is by incorporating fibres in the concrete mix. Concrete incorporated with more than one type of fibres is often known as hybrid concrete. In this paper, the compressive strength of the hybrid concrete when exposed to elevated temperature is studied. The result is compared to concrete mixed with a single type of fibre of polypropylene or steel fibres. An observation of spalling is also carried out to verify the compressive strength test. The test results showed that both the single fibre specimens with steel fibre and hybrid specimen improved by 23.34% and 24.60% in residual strength compared with other residual strengths of concrete specimens.

Natural interspecific hybridization in Odontophrynus (Anura: Cycloramphidae)

The frog genus Odontophrynus is a composite of diploid and tetraploid populations and species that are widely distributed in South America. Some of the several genetic studies on this group report the production of artificial hybrids but only a single case of natural hybridization has been documented, in southern Brazil. In this study we report the finding of an interspecific natural hybrid specimen in central Argentina. We present morphological and cytogenetical evidence that the diploid taxa Odontophrynus cordobae and O. occidentalis are the parental species. The hybrid genome exhibited problematic pairing and segregation of homeologue chromosomes during meiosis, and the production of non-reduced gametes.