Search results for "Grit"
showing 10 items of 192 documents
Soil microbiome of primeval forest ecosystems in Transkarpathia
2018
The aim of this study was to investigate the soil microbiome of primeval forest ecosystems, namely the structure of microbial communities,the number of major ecological-functional groups, functional parameters such as: soil toxicity, as well as enzymatic activity of the soil by the level of catalase and invertase. To analyze the successional processes in the soil microbiocenosis due to the influence of endogenous and exogenous factors. To estimate the integrity of microbial communities in different edaphotopes of primeval forest ecosystems. Methods. Microbiological studies of soil were carried out according to generally accepted methods in soil microbiology. Enzymatic activity of the soil: …
Shape, size, and quantity of ingested external abrasives influence dental microwear texture formation in guinea pigs
2020
Food processing wears down teeth, thus affecting tooth functionality and evolutionary success. Other than intrinsic silica phytoliths, extrinsic mineral dust/grit adhering to plants causes tooth wear in mammalian herbivores. Dental microwear texture analysis (DMTA) is widely applied to infer diet from microscopic dental wear traces. The relationship between external abrasives and dental microwear texture (DMT) formation remains elusive. Feeding experiments with sheep have shown negligible effects of dust-laden grass and browse, suggesting that intrinsic properties of plants are more important. Here, we explore the effect of clay- to sand-sized mineral abrasives (quartz, volcanic ash, loess,…
Synthesis of habitat restoration impacts on young-of-the-year salmonids in boreal rivers
2019
River restoration offers the potential to enhance biological integrity, often measured as fish population changes. We used a meta-analytical approach to synthesize density responses to in-stream habitat restoration by young-of-the year (YOY) brown trout and Atlantic salmon in 28 rivers (overall 32 restoration projects) in Finland. We also examined which local and watershed-scale factors most influenced restoration success. Finally, we conducted an expert survey to obtain an independent estimate of a sufficient density enhancement for restoration to be considered successful. Despite strong context-dependency, habitat restoration had an overall positive effect on YOY salmonid density. When co…
Epinephelus sicanus (Doderlein, 1882) (Perciformes: Serranidae: Epinephelinae), a valid species of grouper from the Mediterranean Sea
2020
During the editing of the paper “In memory of Pietro Doderlein” (Massa et al. 2018), consulting Doderlein’s bibliography, and highlighting some interesting documents and the material preserved in the Museum of Zoology of the University of Palermo (MZPA) (today named after Doderlein), a taxonomic anomaly was noticed about a grouper collected more than one hundred years ago. The aim of the present statement is to prove that the name Cerna sicana Doderlein, 1882 (presently as Epinephelus sicanus [Doderlein, 1882]) should be considered a valid species unless it is demonstrated that it is a synonym of another valid species. In 1882 Doderlein described Cerna sicana from a single specimen (Fig. 1)…
Dust and grit matter: abrasives of different size lead to opposing dental microwear textures in experimentally fed sheep (Ovis aries)
2020
ABSTRACT External abrasives ingested along with the herbivore diet are considered main contributors to dental wear, though how the different sizes and concentrations of these abrasives influence wear remains unclear. Dental microwear texture analysis (DMTA) is an established method for dietary reconstruction which describes a tooth9s surface topography on a micrometre scale. The method has yielded conflicting results as to the effect of external abrasives. In the present study, a feeding experiment was performed on sheep (Ovis aries) fed seven diets of different abrasiveness. Our aim was to discern the individual effects of size (4, 50 and 130 µm) and concentration (0%, 4% and 8% of dry mat…
Solving the Puzzle of Taxonomic Position of the Petroleum Fly by Resurrection of Diasemocera Bezzi from Psilopa Fallén (Diptera: Ephydridae) with Pro…
2018
Diasemocera Bezzi, 1895 (Type species: Psilopa nigrotaeniata Bezzi, 1895 [= Psilopa roederi Girschner, 1889]) is resurrected from synonymy with Psilopa and the following four new synonyms of Diasemocera are proposed: Domina Hutton (Type species: Domina metallica Hutton), Discocerinella Mercier (Type species: Discocerinella omonvillea Mercier, 1927 [= Notiphila pulicaria Haliday, 1839]), Trimerinoides Cresson (Type species: Trimerina adfinis Cresson) and Helaeomyia Cresson, 1941 (Type species: Psilopa petrolei Coquillett). Diasemocera is placed close to the genus Trimerina and it differs from the highly specialized Psilopa and related genera by the number of pseudotracheae (6–7), vestiture o…
Advanced Machining Processes
2017
This chapter provides comprehensive knowledge regarding both well-established achievements in manufacturing and new trends in improving machining processes, taking into account physical, design and technological aspects. The background of machining advancements is outlined, including all components of the machining system and typical machining operations such as turning, milling and drilling and different construction materials. In particular, this short survey covers such machining techniques as high-speed machining/cutting (HSM/HSC), hard part machining, dry and near-dry machining (MQL), high-performance machining (HPM), multitasking/complete machining, and assisted and hybrid machining. …
On the optimization of the cutting conditions for an improved corrosion resistance of OFHC copper
2018
International audience; Machining has a particular impact on the surface integrity and on corrosion resistance of components. In fact, material removal induces geometrical, mechanical and micro-structural modifications in the machined surface and sub-surface that alter the electrochemical behavior of the material, and so the aging process. In this study, oxygen free high conductivity copper (OFHC) has machined under orthogonal cutting conditions using uncoated cemented carbide tools. Then, the corrosion resistance in 0.1 M NaCl salt fog atmosphere of the machined samples is analyzed. Finally, the optimal cutting conditions, including the tool geometry, for an improved corrosion resistance a…
Improving surface integrity of additively manufactured GP1 stainless steel by roller burnishing
2020
Abstract Additive manufacturing can rapidly fabricate the desired components by selectively melting and solidifying feedstock, rather than conventional subtractive machining. However, the difference between the two routes in terms of surface integrity of the final component is relevant. This paper presents a strategy to control the surface characteristics of additively manufactured stainless steel by roller burnishing. In particular, process parameters have been carefully selected to improve the surface integrity of the worked material. The quality of the surface has been analyzed in terms of roughness, hardness, microstructure and residual stresses. The overall product endurance under high…
Friction Model for Tool/Work Material Contact Applied to Surface Integrity Prediction in Orthogonal Cutting Simulation
2017
Abstract Tribological behavior at both tool/chip and tool/work material interfaces should be highly considered while simulating the machining process. In fact, it is no longer accurate to suppose one independent constant friction coefficient at the tool/chip interface, since in reality it depends on the applied contact conditions, including the sliding velocity and pressure. The contact conditions at both above mentioned interfaces may affect the thermal and mechanical phenomena and consequently the surface integrity predictions. In this article, the influence of contact conditions (sliding velocity) on the tribological behavior of uncoated tungsten carbide tool against OFHC copper work mat…